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Restoration of HCV-specific CD8+ T-cell function by Interferon-free therapy.
Abstract
Background & aims:
Chronic hepatitis C virus (HCV) infection is characterised by a failure of virus-specific CD8+ T cells that is mainly caused by viral escape and T cell exhaustion. Constant antigen stimulation has been suggested to contribute to HCV-specific CD8+ T cell exhaustion. However, IFN-based therapies failed to recover HCV-specific CD8+ T cell function suggesting that the damage to CD8+ T cells may be permanent even after antigen removal. It was therefore the objective of this study to analyse the impact of inhibition of ongoing viral replication by IFN-free therapy with direct acting antivirals (DAA) on the phenotype and function of HCV-specific CD8+ T cells.
Methods:
Virus-specific CD8+ T cells obtained from a patient cohort of 51 previously untreated chronically infected patients undergoing IFN-free therapy with a combination of faldaprevir (a protease inhibitor) and deleobuvir (a non-nucleoside polymerase inhibitor) with or without ribavirin were analysed ex vivo and after in vitro expansion at baseline, wk4, wk 12, and after treatment.
Results:
Our results show the rapid restoration of proliferative HCV-specific CD8+ T cells in the majority of patients with SVR12 within 4 weeks of therapy suggesting that IFN-free therapy mediated antigen removal may restore CD8+ T cell function.
Conclusions:
This study indicates a specific restoration of proliferative HCV-specific CD8+ T cells under IFN-free therapy. This is in contrast to PegIFN-based therapies that have been shown not to restore T cell function during and after chronic infection.
... For instance, it has been demonstrated that HCV-specific T cell functions does not completely ameliorate after SVR [19]. In contrast, other studies have observed an increase in T-cell functionality after DAA treatment [20]. It is known that, early impairment of proliferation may contribute to loss of T cell response and chronic HCV persistence [21]. ...
... It is known that, early impairment of proliferation may contribute to loss of T cell response and chronic HCV persistence [21]. Despite the fact that there is not yet a solid evidence that T cell proliferation is fully recovered after HCV cure, several studies have seen a rise in the proliferative profile of CD8 T cells in chronic HCV infected patients after DAA treatment [20,22,23]. While few have observed a partial or inexistent proliferative capacity recovery [24,25]. ...
... Various studies point to the fact that a restoration of HCV-specific CD8+ T cells proliferation after DAAs treatment occurs [20,22,23]. But others reported that CD8 proliferation capacity was not restored after HCV elimination by DAAs in the majority of patients [24,25]. ...
Background & aims:
HCV CD4+ and CD8+ specific T cells responses are functionally impaired during chronic hepatitis C infection. DAAs therapies eradicate HCV infection in more than 95% of treated patients. However, the impact of HCV elimination on immune responses remain controversial. Here, we aimed to investigate whether HCV cure by DAAs could reverse the impaired immune response to HCV.
Methods:
We analyzed 27 chronic HCV infected patients undergoing DAA treatment in tertiary care hospital, and we determined the phenotypical and functional changes in both HCV CD8+ and CD4+ specific T-cells before and after viral clearance. PD-1, TIM-3 and LAG-3 cell-surface expression was assessed by flow cytometry to determine CD4+ T cell exhaustion. Functional responses to HCV were analyzed by IFN-Ɣ ELISPOT, intracellular cytokine staining (IL-2 and IFN-Ɣ) and CFSE-based proliferation assays.
Results:
We observed a significant decrease in the expression of PD-1 in CD4+ T-cells after 12 weeks of viral clearance in non-cirrhotic patients (p = 0.033) and in treatment-naive patients (p = 0.010), indicating a partial CD4 phenotype restoration. IFN-Ɣ and IL-2 cytokines production by HCV-specific CD4+ and CD8+ T cells remained impaired upon HCV eradication. Finally, a significant increase of the proliferation capacity of both HCV CD4+ and CD8+ specific T-cells was observed after HCV elimination by DAAs therapies.
Conclusions:
Our results show that in chronically infected patients HCV elimination by DAA treatment lead to partial reversion of CD4+ T cell exhaustion. Moreover, proliferative capacity of HCV-specific CD4+ and CD8+ T cells is recovered after DAA's therapies.
... Several studies addressed the question how DAA-achieved viral eradication impacts the exhaustion phenotype of SP T-cells, but not DP T-cells. Although the collected data are largely fragmentary and sometimes even contradictory, most of them provided evidence that DAA treatment may result in at least partial restoration of SP T-cell immune function as evidenced by an increase in frequency of CD4 + [47][48][49] and CD8 + T-cells [48] and a shift toward T em (effector memory) population [47,50], with a concomitant decrease in the naïve T-cell subset [50]. Effector function reinvigoration was also observed, manifested by increased frequencies of circulating T helper and cytotoxic T-cells producing IFN-γ, IL-17 and IL-22 [51]. ...
... Effector function reinvigoration was also observed, manifested by increased frequencies of circulating T helper and cytotoxic T-cells producing IFN-γ, IL-17 and IL-22 [51]. Furthermore, a reduction of PD-1 [50] and TIGIT [47,49,50] expression on both CD4 + and CD8 + SP T-cells were reported. ...
In chronic hepatitis C (CHC), characterized by exhaustion of T-cell function, increased frequencies of double-positive (DP) (CD4+CD8+) cells are present in peripheral blood. We compared the exhaustion phenotype between DP and single positive (SP) T-cells, including HCV-specific cells, and assessed the effect of successful HCV treatment on inhibitory receptors expression. Blood samples from 97 CHC patients were collected before and six months post-treatment. PD-1 (programmed cell death protein 1) and Tim-3 (T-cell immunoglobulin and mucin domain-containing molecule-3) expression was assessed by flow cytometry. DP T-cells displayed significantly higher PD-1 expression, lower Tim-3 expression than CD8+ SP T-cells and lower percentages of PD-1−Tim-3− cells than CD4+ SP T-cells, both before and after treatment. PD-1+Tim-3+ DP T-cells decreased following treatment. HCV-specific cells were more frequent among DP than SP T-cells, both before and after treatment. HCV-specific DP T-cells were characterized by lower PD-1 expression, higher PD-1 and Tim-3 co-expression, and lower percentages of PD-1−Tim-3− cells (both before and after treatment) and higher post-treatment Tim-3 than HCV-specific SP T-cells. Their percentages decreased following treatment, but the exhaustion phenotype remained unchanged. DP T-cells in CHC exhibit a distinct exhaustion phenotype from SP T-cells, and these changes mostly persist following successful treatment.
... Compromised restoration of CD4 + T cell frequency during ART HCV induced hepatic inflammation and immune activation lead to altered T cell homeostasis (193) Partial restoration of T cell compartment and memory profile (194) Deterioration of CD8 + T cell function Persistent liver inflammation contributes to generalized exhaustion of CD8 + T cells with upregulation of exhaustion molecules like PD-1, Tim-3 and CD39 on total and virus-specific CD8 + T cells (195)(196)(197) Partial reversal of CD8 + T cell exhaustion (49,198) Augmentation of HIV replication. NS3/4A: activates binding of AP-1 to LTR, facilitated by Vpu leading to increased HIV RNA reverse transcription into cDNA to be integrated in the host genome (199,200). ...
... In HCV monoinfection, DAA treatment was associated with restoration of the proliferative capacity of HCV-specific CD8 + T cells (198). However, selective maintenance of TCF1 + CD127 + PD1 + memory like HCV-specific CD8 + T cells was observed following cessation of therapy (47), as well as a limited impact of DAA on the functional and mitochondrial impairment of HCV-specific CD8 + T cell responses (232). ...
Nearly 2.3 million individuals worldwide are coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV). Odds of HCV infection are six times higher in people living with HIV (PLWH) compared to their HIV-negative counterparts, with the highest prevalence among people who inject drugs (PWID) and men who have sex with men (MSM). HIV coinfection has a detrimental impact on the natural history of HCV, including higher rates of HCV persistence following acute infection, higher viral loads, and accelerated progression of liver fibrosis and development of end-stage liver disease compared to HCV monoinfection. Similarly, it has been reported that HCV coinfection impacts HIV disease progression in PLWH receiving anti-retroviral therapies (ART) where HCV coinfection negatively affects the homeostasis of CD4+ T cell counts and facilitates HIV replication and viral reservoir persistence. While ART does not cure HIV, direct acting antivirals (DAA) can now achieve HCV cure in nearly 95% of coinfected individuals. However, little is known about how HCV cure and the subsequent resolution of liver inflammation influence systemic immune activation, immune reconstitution and the latent HIV reservoir. In this review, we will summarize the current knowledge regarding the pathogenesis of HIV/HCV coinfection, the effects of HCV coinfection on HIV disease progression in the context of ART, the impact of HIV on HCV-associated liver morbidity, and the consequences of DAA-mediated HCV cure on immune reconstitution and HIV reservoir persistence in coinfected patients.
... Nevertheless, a small fraction of T EX may persist following antigen elimination, and some T EX features may recover 6,7,33,34 . In patients who have been cured of chronic hepatitis C virus (HCV), previously exhausted HCV-specific CD8 T cells can persist and display reduced PD-1 expression and improved function, perhaps due to persistence of Prog-T EX [35][36][37] . A key question is what changes occur phenotypically, functionally, transcriptionally and epigenetically to T EX and T EX subsets upon cure of chronic disease. ...
... Collectively, these data indicate that T EX transferred into infection-free mice displayed mixed T EX and T MEM features (Fig. 1h), suggesting partial recovery from exhaustion. These results are consistent with observations post-cure of human HCV infection [35][36][37] . These donor T EX at 4+ weeks post-transfer will hereafter be termed recovering T EX (REC-T EX ). ...
Exhausted CD8 T cells (TEX) are a distinct state of T cell differentiation associated with failure to clear chronic viruses and cancer. Immunotherapies such as PD-1 blockade can reinvigorate TEX cells, but reinvigoration is not durable. A major unanswered question is whether TEX cells differentiate into functional durable memory T cells (TMEM) upon antigen clearance. Here, using a mouse model, we found that upon eliminating chronic antigenic stimulation, TEX cells partially (re)acquire phenotypic and transcriptional features of TMEM cells. These ‘recovering’ TEX cells originated from the T cell factor (TCF-1+) TEX progenitor subset. Nevertheless, the recall capacity of these recovering TEX cells remained compromised as compared to TMEM cells. Chromatin-accessibility profiling revealed a failure to recover core memory epigenetic circuits and maintenance of a largely exhausted open chromatin landscape. Thus, despite some phenotypic and transcriptional recovery upon antigen clearance, exhaustion leaves durable epigenetic scars constraining future immune responses. These results support epigenetic remodeling interventions for TEX cell–targeted immunotherapies. Wherry and colleagues examine whether exhausted T cells (TEX) can differentiate into functional memory T cells (TMEM) when chronic antigen is withdrawn. Using the chronic LCMV infection mouse model, they show that ‘recovering’ TEX cells (REC-TEX) only partially recover immunophenotypic and functional characteristics of TMEM cells. The epigenomic status of REC-TEX cells more closely resembles that of TEX cells, and, upon rechallenge, the REC-TEX cells were still compromised in their ability to respond to virus.
... Previous studies have analyzed HCV patients treated with DAAs and found varying degrees of functional reconstitution of T cells (21,22) and natural killer cells (NKs) (23,24) following viral clearance. Studies focusing on NKs, for instance, have Significance Chronic inflammation contributes to morbidity and mortality in aging, but whether similar mechanisms underlie dysfunction in infection-associated chronic inflammation is unclear. ...
... This anti-HCV differentiation is affected by STAT4 signaling (51,(53)(54)(55)(56)(57), which we also see in this community in CD4 + T cells and monocytes. The lack altogether of a dedicated MAPK functional module posttreatment suggests that the MAPK communities are at least partially maintained by HCV-specific antigen receptor signaling in lymphocytes (50)(51)(52)58), as their abundance have been shown to increase during successful DAA treatment to reduce the antigenic burden (21,59). ...
Significance
Chronic inflammation contributes to morbidity and mortality in aging, but whether similar mechanisms underlie dysfunction in infection-associated chronic inflammation is unclear. Using a multicohort systems immunology approach, we identified signatures of immune dysfunction that are shared in aging and chronic viral infections, namely HIV and hepatitis C virus. We show that these shared dysfunctions persist despite viral clearance, and we describe the changes in functional coordination that occur during viral eradication. Finally, we highlight a partial restoration in interferon-α sensitivity across all major immune cell lineages as viral load drops. Our findings suggest a broad and persistent functional remodeling and deterioration of the human immune system despite removal of a chronic pathogenic burden that shares features of chronic inflammation in aging.
... Virologic relapse occurs in some patients, but not others, for reasons that are poorly understood and do not always relate to viral resistance or medication adherence [1][2][3]. The majority of patients treated with DAAs experience rapid down-regulation of endogenous interferon activity and changes in the distribution and function of innate and adaptive immune cells in liver and peripheral blood [4][5][6][7][8]. ...
... Multiple interferon stimulated genes (ISGs) decreased during treatment, consistent with previous findings (Figure 1) [4][5][6]13], while type-I and type-III IFN receptor expression did not change. Expression of ISGs and IFN receptors did not differ pre-or post-treatment based on treatment outcome (data not shown). ...
To identify immunologic correlates of hepatitis C virus (HCV) relapse after direct-acting antiviral (DAA) therapy, we quantified select immune transcripts in whole blood from noncirrhotic HCV subjects treated with 4–6 weeks of DAAs. We identified specific markers of natural killer-cell and CD8+ T-cell function (GZMB, PRF1, NKp46) with higher expression in subjects who relapsed. These findings suggest a role for host immunity in HCV eradication with ultrashort DAA therapy.
We quantified whole blood immune transcripts in noncirrhotic HCV subjects treated with shortcourse antiviral therapy. Markers of natural killer-cell and CD8+ T-cell function had higher expression in virologic relapsers, suggesting a role for host immunity in HCV eradication.
... The mean survival time of all non-HPV associated HNSCC patients was 38 43.6%; P = .035). ...
... Anti-HCV treatment is mainly based on interferon alpha or direct-acting anti-viral agents (DAA), which both reduce HCV vial loads and stimulate immunity leading a better outcomes for HCVpositive patients. 43 But, among these HNSCC patients without anti-HCV treatment in our study, high expression of HCV RNA, similar to HPV, might favor prognosis of HNSCC patients as compared to HNSCC patients with low HCV transcript. If an ideal clinical trial would be implemented in future, it would be worth of test whether the overall survival rate will successively increase from HCV negative HNSCC patients, HCV positive HNSCC patients without HCV treatment to HCV positive HNSCC patients with HCV treatment. ...
Objective/Hypothesis
Hepatitis C virus (HCV) was reported to associate with head and neck squamous cell carcinoma (HNSCC) in many studies. However, its correlation with prognosis of non‐human papillomavirus (HPV) associated HNSCC remains unknown. Here, we sought to investigate clinical significance of HCV RNA transcript in non‐HPV associated HNSCC by analyzing corresponding RNA‐seq data.
Study Design
A retrospective cohort study.
Methods
Four hundred and forty‐eight non‐HPV associated HNSCC patients with aligned RNA‐seq and clinical follow‐up data were included and divided into two groups: low‐HCV and high‐HCV. Means of continuous variables and proportions of categorical variables were compared using independent sample t‐test and chi‐square test, respectively. Survival data were compared using Cox regression analysis, Kaplan–Meier curves, and log‐rank test. Expression of genome‐wide mRNAs and abundance of immune cells were compared using volcano plot and cell signature estimated score analysis.
Results
HCV RNA transcript negatively correlates with pathologic (P = .028) and clinical‐stage (P = .023), clinical N stage (P = .025), and nodal extracapsular spread (P = .042) and is an independent prognosis factor in non‐HPV associated HNSCC (HR = 1.488; 95% CI: 1.004–2.206; P = .048). Elevated expression of HCV improved 5‐year overall survival (43.6% vs. 53.2%; P = .035) in all non‐HPV associated HNSCC patients, the same as in male (46.6% vs. 58.7%; P = .049), clinical M0 stage (42.8% vs. 52.9%; P = .036), white (42.9% vs. 55.9%; P = .010), and histologic grade 1 to 2 subgroups (42.1% vs. 57.2%; P = .043). The expression of several immune‐related genes and abundance of some immune cells significantly changed with the increase of HCV RNA transcript, while HCV‐related oncogenes and tumor suppressor gene did not.
Conclusions
HCV RNA transcript is an independent favorable factor for prognosis of non‐HPV associated HNSCC.
Levels of Evidence
4 Laryngoscope, 2021
... Peg-IFN-α-based therapies have been reported to not restore virus-specific T-cell function even after HCV is cleared [7]. An initial report regarding DAA treatment, demonstrated that it may partially reinvigorate exhausted virus-specific T cells [72]. Following DAA therapy, some degree of enhancement in the in vitro proliferation of HCV-specific CD8 + T cells was observed after peptide stimulation [72]. ...
... An initial report regarding DAA treatment, demonstrated that it may partially reinvigorate exhausted virus-specific T cells [72]. Following DAA therapy, some degree of enhancement in the in vitro proliferation of HCV-specific CD8 + T cells was observed after peptide stimulation [72]. However, our group recently demonstrated that DAA-mediated viral clearance only transiently restores ex vivo virus-specific T-cell function [73]. ...
Direct-acting antiviral agents (DAAs) that allow for rapid clearance of hepatitis C virus (HCV) may evoke immunological changes. Some cases of rapid de novo hepatocellular carcinoma (HCC) development or early recurrence of HCC after DAA treatment have been reported. During chronic HCV infection, natural killer (NK) cells exhibited a deviant functional phenotype with decreased production of antiviral cytokines and increased cytotoxicity; however, DAA treatment rapidly decreased their cytotoxic function. Effective DAA therapy also suppressed the intrahepatic activation of macrophages/monocytes. This was followed by a decrease in mucosal-associated invariant T (MAIT) cell cytotoxicity without normalization of cytokine production. Rapid changes in the phenotypes of NK and MAIT cells after DAA treatment may attenuate the cytotoxicity of these cells against cancer cells. Moreover, DAA treatment did not normalize the increased frequencies of regulatory T cells even after clearance of HCV infection. Thus, the persistently increased frequency of regulatory T cells may contribute to a local immunosuppressive milieu and hamper the clearance of cancer cells. This review will focus on recent studies describing the changes in innate and adaptive immune responses after DAA treatment in patients with chronic HCV infection in the context of de novo occurrence or recurrence of HCC.
... Expression of multiple co-regulatory molecules such as PD-1, 2B4, TIM-3, Lag-3, CD5, CD160, and TIGIT is upregulated on HCV-specific CD8 T cells during chronic HCV infection [11,70], and is associated with poor proliferative and functional response. Varying levels of restoration of proliferation capacity of these virus-specific CD8 + T cells are observed following cessation of antigenic stimulation after DAA therapy-mediated viral clearance [77,78]. Factors that impact the proliferation capacity of the HCV-specific CD8 T cells upon peptide stimulation include the presence of cells recognizing the conserved epitopes [77], gender, presence of advance fibrosis [78], and combination of drugs used in the DAA regimen. ...
... Varying levels of restoration of proliferation capacity of these virus-specific CD8 + T cells are observed following cessation of antigenic stimulation after DAA therapy-mediated viral clearance [77,78]. Factors that impact the proliferation capacity of the HCV-specific CD8 T cells upon peptide stimulation include the presence of cells recognizing the conserved epitopes [77], gender, presence of advance fibrosis [78], and combination of drugs used in the DAA regimen. Aregay A et al. showed a significant decrease in activation markers, CD38 and HLA-DR, on HCV-specific CD8 + T cells after DAA-mediated clearance of HCV and no significant reduction in the expression exhaustion markers, PD-1, TIM3, LAG3, and CD5 [78]. ...
Chronic HCV (CHC) infection is the only chronic viral infection for which curative treatments have been discovered. These direct acting antiviral (DAA) agents target specific steps in the viral replication cycle with remarkable efficacy and result in sustained virologic response (SVR) or cure in high (>95%) proportions of patients. These treatments became available 6–7 years ago and it is estimated that their real impact on HCV related morbidity, including outcomes such as cirrhosis and hepatocellular carcinoma (HCC), will not be known for the next decade or so. The immune system of a chronically infected patient is severely dysregulated and questions remain regarding the immune system’s capacity in limiting liver pathology in a cured individual. Another important consequence of impaired immunity in patients cleared of HCV with DAA will be the inability to generate protective immunity against possible re-infection, necessitating retreatments or developing a prophylactic vaccine. Thus, the impact of viral clearance on restoring immune homeostasis is being investigated by many groups. Among the important questions that need to be answered are how much the immune system normalizes with cure, how long after viral clearance this recalibration occurs, what are the consequences of persisting immune defects for protection from re-infection in vulnerable populations, and does viral clearance reduce liver pathology and the risk of developing hepatocellular carcinoma in individuals cured with these agents. Here, we review the recent literature that describes the defects present in various lymphocyte populations in a CHC patient and their status after viral clearance using DAA treatments.
... Our findings in this study indicated, first, that miR-23a expression was down-regulated following antiviral therapy (HCV clearance). These findings are consistent with previous reports by Nattermann et al. [13] and Bogdanovi et al. [14], who found that INF/RBV therapy resulted in significantly higher SVR rates, most likely due to IL-6 mediated STAT3 activation in HCV/HIV co-infected patients' response to INF/RBV therapy and low-producing IL-6 with spontaneous HCV clearance, respectively. MiR-23a was revealed to down regulate the interleukin-6 receptor, boosting the development of gastric cancer cells. ...
Background
MicroRNAs (miR) are small sequence of nucleotides that can affect multiple genes involved in the hepatitis C virus (HCV) life cycle and disease development. The purpose of the present study was to investigate the clinical significance of serum microRNA profiles in a cohort of Egyptian patients with chronic HCV infection before and after combined sofosbuvir and daclatasvir treatment, as well as to gain a better understanding of the exact interaction mechanism in HCV transcriptional activity via differentially expressed miRNAs. For 12 weeks, 50 patients were eligible for and received sofosbuvir (400 mg daily) and daclatasvir (60 mg daily) treatment. Each patient’s blood was obtained twice: once before therapy began and again three months afterwards.
Results
The current study found that serum levels of circulating miR-122, miR-221, miR-23a, miR-125, miR-217, miR-224, and miR-181a were high in HCV pre-treatment patients, but after 12 weeks of direct-acting antiviral (DAAs) treatment, there was a statistically significant reduction in expression levels of miR-122, miR-221, miR-23a, miR-125, miR-217, and miR-224 (p < 0.001). There is no statistical significance for miR-181a.
Conclusion
The key differentially expressed microRNAs before and after the direct-acting antiviral (DAA) regimen were connected to the dynamics of chronic HCV infection, suggesting their potential as predictive biomarkers for HCV clearance after sofosbuvir and daclatasvir therapy.
... Initial reports documented a reversal of T cell exhaustion post-DAA treatment, characterized by enhanced proliferation of HCV-specific CD8+ T cells [96], diminished PD-1 expression [97][98][99], and a transition toward a TCF-1+CD127+ memory-like T cell phenotype [100]. However, one study found that only a partial restoration of immune responses could be obtained in HCV patients treated with DAAs, with increased proliferation of HCV-specific CD4 and CD8 T cells, accompanied by an impaired ability to secrete IFNγ and IL2 [101]. ...
Hepatitis C virus (HCV) has spread worldwide, and it is responsible for potentially severe chronic liver disease and primary liver cancer. Chronic infection remains for life if not spontaneously eliminated and viral persistence profoundly impairs the efficiency of the host’s immunity. Attempts have been made to develop an effective vaccine, but efficacy trials have met with failure. The availability of highly efficacious direct-acting antivirals (DAA) has created hope for the progressive elimination of chronic HCV infections; however, this approach requires a monumental global effort. HCV elicits a prompt innate immune response in the host, characterized by a robust production of interferon-α (IFN-α), although interference in IFN-α signaling by HCV proteins may curb this effect. The late appearance of largely ineffective neutralizing antibodies and the progressive exhaustion of T cells, particularly CD8 T cells, result in the inability to eradicate the virus in most infected patients. Moreover, an HCV cure resulting from DAA treatment does not completely restore the normal immunologic homeostasis. Here, we discuss the main immunological features of immune responses to HCV and the epigenetic scars that chronic viral persistence leaves behind.
... Initial reports documented a reversal of T cell exhaustion post-DAA treatment, characterized by enhanced proliferation of HCV-specific CD8+ T cells [79], diminished PD-1 expression [80][81][82], and a transition toward a TCF-1+CD127+ memory-like T cell phenotype [83]. However, one study found that only partial restoration of immune responses could be obtained in HCV patients treated with DAA, with increased proliferation of HCV-specific CD4 and CD8 T-cells, accompanied by an impaired ability to secrete IFNγ and IL2 [84]. ...
Hepatitis C virus (HCV) is diffused worldwide, and it is responsible for potentially severe chronic liver disease and primary liver cancer. Chronic infection remains for life if not spontaneously eliminated and viral persistence profoundly impairs the efficiency of host’s immunity. Attempts have been made to develop an effective vaccine, but efficacy trials have met with failure. The availability of highly efficacious direct acting antivirals (DAA) has shed hopes for progressive elimination of chronic HCV infection; however, this approach requires a global monumental effort. Moreover, DAA treatment does not completely restore the normal immunologic homeostasis. Here we discuss the main immunological features of immune responses to HCV and the epigenetic scars that chronic viral persistence leaves behind.
... Since 2015, highly effective direct-acting antiviral (DAA) therapy has revolutionised the treatment of chronic HCV infection, with standard cure rates exceeding 95% [126,127]. Many studies have shown that, following IFN-free DAA treatment, both innate and adaptive immune homeostasis may be partially restored [127][128][129]. To clarify the role of DAAmediated HCV eradication in global T cell immune function, Rosen et al. utilised scRNA-seq to characterise the transcriptome of circulating T cells before, during, and after the DAA-mediated HCV cure [130]. ...
The liver is an immune organ that plays a vital role in the detection, capture, and clearance of pathogens and foreign antigens that invade the human body. During acute and chronic infections, the liver transforms from a tolerant to an active immune state. The defence mechanism of the liver mainly depends on a complicated network of intrahepatic and translocated immune cells and non-immune cells. Therefore, a comprehensive liver cell atlas in both healthy and diseased states is needed for new therapeutic target development and disease intervention improvement. With the development of high-throughput single-cell technology, we can now decipher heterogeneity, differentiation, and intercellular communication at the single-cell level in sophisticated organs and complicated diseases. In this concise review, we aimed to summarise the advancement of emerging high-throughput single-cell technologies and re-define our understanding of liver function towards infections, including hepatitis B virus, hepatitis C virus, Plasmodium , schistosomiasis, endotoxemia, and corona virus disease 2019 (COVID-19). We also unravel previously unknown pathogenic pathways and disease mechanisms for the development of new therapeutic targets. As high-throughput single-cell technologies mature, their integration into spatial transcriptomics, multiomics, and clinical data analysis will aid in patient stratification and in developing effective treatment plans for patients with or without liver injury due to infectious diseases.
... These contradictory results have increased commentaries and criticism about this controversial issu 24 . Despite the unclear effects of DAAS therapy on the rate of HCC occurrence or recurrence, it would be important to study the immunological alterations in CHC patients treated with DAAS [25][26] . ...
Background:
During the first years of the use of direct acting Hepatitis C antiviral drugs (DAAS), several studies reported a possible correlation between this new era of treatment and an increased risk of Hepatocellular carcinoma (HCC). Its development could possibly be favored by the changes in the immunological milieu and the different cellular behavior after eradication of HCV infection with them. For this reason, this study aimed to address the immunological effect of DAAS.
Subject & methods:
Prospective paired -sample design, carried out on 90 naïve chronically infected HCV patients before and after receiving a combination therapy of sofosbuvir; at a dose of 400 mg once daily and daclatasvir; at a dose of 60 mg once daily for 12 weeks and follow up for one year. immunological tests including: total T cell count, T helper cell count, T cytotoxic cell count and natural killer cell count in peripheral blood through (CD3, CD3/CD4, CD3/CD8 and CD56 respectively) by Fluorochrome monoclonal antibodies labelled with specific dyes through Multiparameter, FACSCanto ™ II flow cytometer (Becton Dickinson, USA).
Result:
Concerning the immunological changes, total T cells (CD3+), Natural killer cells showed non-significant decrease at end of therapy while significant decrease in T helper cells (CD3+CD4+) T cytotoxic cells (CD3+CD8+) compared to pre-treatment value. Long follow up revealed 26.6% developed focal HCC, in more addition, multivariate analysis show CD4/CD8 ratio could be predictor as well as sex for early development of HCC after combined DAAS therapy.
Conclusion:
HCV treatment by DAAS produces significant decrease in T helper, T cytotoxic cells in CHC patients at the end of therapy. 26.6% developed focal HCC with independent CD4/CD8 predictor for burden malignancy. Further large extended population study is needed for clarify this concern.
... The immunological response after eradication of HCV using IFN-free DAA therapies is not well defined. Several studies suggest a partial immunological recovery after treatment [42][43][44]. In our study, we found a different immune profile in the two populations in the monocyte and lymphocyte compartments as well as in levels of soluble markers after DAA treatment. ...
In the direct-acting antiviral (DAA) era, it is important to understand the immunological changes after HCV eradication in HCV monoinfected (mHCV) and in HIV/HCV coinfected (HIV/HCV) patients. In this study, we analyzed sub-populations of monocytes, dendritic cells (DCs), T-lymphocytes and inflammatory biomarkers following initiation of DAA in 15 mHCV and 16 HIV/HCV patients on effective antiretroviral therapy at baseline and after sustained virological response at 12 weeks (SVR12). Fifteen age- and sex-matched healthy donors (HD) were enrolled as a control group. Activated CD4+ and CD8+ T-lymphocytes, mDCs, pDCs, MDC8 and classical, non-classical and intermediate monocytes were detected using flow cytometry. IP-10, sCD163 and .sCD14 were assessed by ELISA while matrix metalloproteinase-2 (MMP-2) was measured by zymography. At baseline, increased levels of IP-10, sCD163 and MMP-2 were found in both HIV/HCV and mHCV patients compared to HD, whereas sCD14 increased only in HIV/HCV patients. After therapy, IP-10, sCD163 and sCD14 decreased, whereas MMP-2 persistently elevated. At baseline, activated CD8+ T-cells were high in HIV/HCV and mHCV patients compared to HD, with a decrease at SVR12 only in HIV/HCV patients. Activated CD4+ T-cells were higher in HIV/HCV patients without modification after DAAs therapy. These results suggest complex interactions between both viruses and the immune system, which are only partially reversed by DAA treatment.
... 28 Similarly, during DAA-mediated HCV clearance, HCV-specific CD8 þ T-cell proliferative capacity improved, along with augmented IFNg responses, to restore antiviral effector functions. 29 The present study investigated, for the first time, phenotypic changes and the expression of 16 different inhibitory/ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 stimulatory ICPs in the serum of HCV patients, before and after antiviral treatment, and at the time of the HCC detection. SVR achievement was associated with decreased levels of 12 of 16 soluble ICPs analyzed, including both stimulatory and inhibitory factors. ...
Factors affecting the probability of hepatocellular carcinoma (HCC) development even after sustained virological response (SVR) following anti-HCV therapy remain unelucidated. This study characterized the role of 16 soluble immune checkpoint proteins (ICPs) in 168 HCV-SVR patients with 47 developing HCC at the study endpoint. At baseline, high concentrations of 10 ICPs were found in the sera of the HCC group. At the study endpoint, levels of sCD27, sCD28, sCD40, and sCD86 in the HCC group, which were depleted following SVR, returned to higher levels than those of the non-HCC group. Importantly, patients with baseline levels of sCD27 ≥ 4104, sCD28 ≥ 1530, and sCD40 ≥ 688 pg/mL predicted a significantly greater HCC cumulative rate. While sCD27 was elevated in patient sera, its membrane-bound form, mCD27, accumulated in the tumor and peri-tumor area, mainly localized in T cells. Interestingly, T cell activation time-dependently induced sCD27. Furthermore, CD70, the ligand of CD27, was robustly expressed in HCC area in which CD70 promoter methylation analysis indicated the hypomethylation compared with the non-tumor pairs. Recombinant human CD27 treatment induced the proliferation of CD70-bearing HepG2 cells via the MEK-ERK pathway, but not NF-κB or p38 pathway. In conclusion, baseline sCD27, sCD28, and sCD40 levels could be used as HCC prognostic markers in HCV-SVR patients. sCD27 likely promotes HepG2 cell growth via the CD27-CD70 axis.
... Higher baseline expression level of hepatic interferon stimulated genes (ISGs) is a predictor of SVR12 after DAA treatment (Alao et al., 2018) and HCV clearance by DAA therapy causes a downregulation of ISGs with a shift in the interferon response (Meissner et al., 2014) and a restoration of a normal natural killer (NK) cell phenotype and function (Serti et al., 2015;Nakamura et al., 2018). In addition, the HCV antigen removal mediated by DAA restores the function of HCV specific CD8 + T cells including decreased levels of PD-1 expression (Martin et al., 2014). ...
Reducing the treatment duration for chronic hepatitis C could be an important tool in the effort to reach the elimination goals set by the World Health Organization. The current challenge is to predict the target group who will achieve sustained virological response at week 12 (SVR12) with shorter treatment duration. The aim of this exploratory study was to characterize immune subsets with focus on inhibitory receptors in patients who experienced SVR12 or virological relapse following four weeks treatment with glecaprevir/pibrentasvir with or without ribavirin. A total of 32 patients were included in this study of whom 21 achieved SVR12 and 11 had virological relapse. All available samples at baseline (n = 31) and end of treatment (EOT) (n = 30) were processed for flow cytometric analysis in order to measure the expression of PD-1, 2B4, BY55, CTLA-4, TIM-3 and LAG-3 on 12 distinct T cell subsets. At baseline, patients with SVR12 (n=21) had numerically lower frequencies of inhibitory receptors for 83% (60/72) of the investigated T-cell subtypes. The most significant difference observed between the two groups was a lower frequency of stem cell-like memory T-cells CD4+PD1+ in the SVR group (p = 0.007). Furthermore, we observed a significant positive correlation between baseline viral load and the expression of PD-1 on the total CD8+ T-cells and effector memory T-cells CD4+ and CD8+ for patients with virological relapse. This study suggests a measurable immunologic phenotype at baseline of patients achieving SVR12 after short treatment compared to patients with virological relapse.
... Most recent in-vitro studies clearly showed that co-infected cells produce fewer HBV transcripts, progeny viruses, and antigens, due to the hampered HBV replication and transcription caused by the HCV-induced IFN response [6]. The role of the adaptive immunity appears to be minor, since HCV has not been shown to affect the T cell response of HBV in coinfected patients [32], nor did HCV clearance after DAAs [33]. Taken together, our results are in line with the in-vitro evidence that HBV reactivation is the consequence of a diminished hepatic IFN response following HCV clearance. ...
Direct-acting antivirals (DAAs) for hepatitis C virus (HCV) may induce hepatitis B virus (HBV) reactivations in co-infected patients, whose dynamics and outcomes could depend on the phase of HBV infection. We investigated HBsAg and HBV-DNA kinetics in fifteen untreated HBeAg Negative Infection (ENI) (4F-11M, 62.1y) and eight Nucleos(t)ide Analogs (NAs) treated Chronic Hepatitis B (CHB) (3F-6M, 54.8y) with HCV co-infection, receiving DAAs-regimens including Sofosbuvir (13) or not (10). All achieved a sustained virologic response (SVR) and normalized alanine-aminotransferase (ALT). At the direct acting antivirals’ (DAAs) baseline (BL), the HBV-DNA was undetectable (<6 IU/mL) in eight ENI and all CHB, the mean Log-HBsAg was lower in ENI than CHB (0.88 vs. 2.42, p = 0.035). During DAAs, HBV-DNA increased in untreated ENI by >1 Log in five and became detectable in two. Accordingly, mean BL Log-HBV-DNA (0.89) increased at week-4 (1.78; p = 0.100) and at the end of therapy (1.57; p = 0.104). Mean Log-HBsAg decreased at week-4 in ENI (from 0.88 to 0.55; p = 0.020) and CHB (from 2.42 to 2.15; p = 0.015). After DAAs, the HBsAg returned to pre-treatment levels in CHB, but not in ENI (six cleared HBsAg). Female gender and SOF were associated with a greater HBsAg decline. In conclusion, HBV reactivations during DAAs in HCV co-infected ENI caused moderate increases of HBV-DNA without ALT elevations. The concomitant HBsAg decline, although significant, did not modify individual pre-treatment profiles.
... IFN-based therapy failed to recover the function of HCV-specific CD8+ T cells. This result suggested that the damage to CD8+ T cells might be permanent even after virus elimination [10]. In contrast, the combination of deleobuvir and faldaprevir resulted in the downregulation of programmed death-1, which led to rapid restoration of HCV-specific CD8+ T cell functions [11]. ...
Background:
Chronic hepatitis C virus (HCV) infection induces profound alterations in the cytokine and chemokine signatures in peripheral blood. Clearance of HCV by antivirals results in host immune modification, which may interfere with immune-mediated cancer surveillance. Identifying HCV patients who remain at risk of hepatocellular carcinoma (HCC) following HCV eradication remains an unmet need. We hypothesized that antiviral therapy-induced immune reconstruction may be relevant to HCC development.
Aim:
To investigate the impact of differential dynamics of cytokine expression on the development of HCC following successful antiviral therapy.
Methods:
One hundred treatment-naïve HCV patients with advanced fibrosis (F3/4) treated with direct-acting antivirals (DAAs) or peginterferon/ribavirin who achieved sustained virologic response [SVR, defined as undetectable HCV RNA throughout 12 wk (SVR12) for the DAA group or 24 wk (SVR24) for the interferon group after completion of antiviral therapy] were enrolled since 2003. The primary endpoint was the development of new-onset HCC. Standard HCC surveillance (abdominal ultrasound and α-fetoprotein) was performed every six months during the follow-up. Overall, 64 serum cytokines were detected by the multiplex immunoassay at baseline and 24 wk after end-of-treatment.
Results:
HCC developed in 12 of the 97 patients over 459 person-years after HCV eradication. In univariate analysis, the Fibrosis-4 index (FIB-4), hemoglobin A1c (HbA1c), the dynamics of tumor necrosis factor-α (TNF-α), and TNF-like weak inducer of apoptosis (TWEAK) after antiviral therapy were significant HCC predictors. The multivariate Cox regression model showed that ΔTNF-α (≤ -5.7 pg/mL) was the most important risk factor for HCC (HR = 11.54, 95%CI: 2.27-58.72, P = 0.003 in overall cases; HR = 9.98, 95%CI: 1.88-52.87, P = 0.007 in the interferon group). An HCC predictive model comprising FIB-4, HbA1c, ΔTNF-α, and ΔTWEAK had excellent performance, with 3-, 5-, 10-, and 13-year areas under the curve of 0.882, 0.864, 0.903, and 1.000, respectively. The 5-year accumulative risks of HCC were 0%, 16.9%, and 40.0% in the low-, intermediate-, and high-risk groups, respectively.
Conclusion:
Downregulation of serum TNF-α significantly increases the risk of HCC after HCV eradication. A predictive model consisting of cytokine kinetics could ameliorate personalized HCC surveillance strategies for post-SVR HCV patients.
... DAAmediated HCV clearance was associated with the preferential maintenance of memory-like cells [85]. This is consistent with the fact that DAA treatment results in only partial reversal of T cell exhaustion, whereby proliferative responses are restored but the capacity to produce cytokines or cytotoxicity are not [85,87,88]. ...
Over the past decade, tremendous progress has been made in systems biology-based approaches to studying immunity to viral infections and responses to vaccines. These approaches that integrate multiple facets of the immune response, including transcriptomics, serology and immune functions, are now being applied to understand correlates of protective immunity against hepatitis C virus (HCV) infection and to inform vaccine development. This review focuses on recent progress in understanding immunity to HCV using systems biology, specifically transcriptomic and epigenetic studies. It also examines proposed strategies moving forward towards an integrated systems immunology approach for predicting and evaluating the efficacy of the next generation of HCV vaccines.
... Martin et al. proved that DAAs apart from their direct action of HCV also boosts the immune system to fight against the virus, the mechanism very similar to that of interferons. 30,31 All 3 relapsers have attained ETR and then relapsed again, suggesting that the viral pool in these patients had DAA mutant variants as well. Interferon resistance is not based upon mutations related to nonstructural proteins like NS3 to NS5B 29 , which are the main targets of DAAs. ...
The global prevalence of Anti HCV is estimated to be about 1.6% with a viraemic prevalence of about 1.1% roughly accounting 80 million worldwide population.1 Genotype 1 has got the highest global genotype distribution of about 46% followed by Genotype 3 with 22 %.1 The natural history of the disease suggests that up to 85% patients remain HCV infected once they acquire acute hepatitis C infection.2 That is why the treatment for hepatitis C is revolutionizing since 1986 when for the first-time interferon was used.3 Till recent past, the standard treatment for Hepatitis C was a combination of pegylated interferon alfa and ribavirin for 48 weeks for genotype 1 and 24 weeks for genotype 2 and 3.2 A breakthrough in the treatment was long awaited not only because of the unsatisfactory sustained viral response rate but also because of limited use due to side effects and contraindications.4,5 Sofosbuvir, a nucleotide analogue inhibitor of
HCV NS5B polymerase, has been approved by FDA since 2013, in combination with pegylated interferon alfa and ribavirin for 12 weeks in genotype 1 or 4 and in combination with ribavirin for genotype 2 (12 weeks) or 3 (24 weeks) respectively.6 Varying data has been shared so far around the globe, with maximum representation from the western world focusing on genotype 1.7–9
... Major features of the adaptive immune response during chronic infection include loss of HCV-specific CD4 + T cell help [17,18,26,[160][161][162] and failure of the HCV-specific CD8 + T cell response due to exhaustion [163][164][165] or emergence of viral escape mutations that prevent the recognition of CD8 + T cell epitopes [166][167][168][169]. Studies done since the introduction of DAA therapies have begun to shed light on how immunity continues to change after recovery from viral infection and, importantly, how this new immune state is markedly different from that which is observed after spontaneous resolution of infection. It has been observed that HCV-specific CD8 + T cell populations expand following DAA-mediated viral clearance [170,171], though in a chimpanzee study, this expansion occurred preferentially in CD8 + T cells that were previously dominant and had targeted escaped epitopes [172]. In human studies, expanded HCV-specific CD8 + T cell populations observed post-DAA cure have a better capacity to proliferate and produce antiviral cytokines than prior to treatment, though these cells are neither as proliferative nor as functional as those observed in acute resolving infection [171,173]. ...
Thirty years after its discovery, the hepatitis C virus (HCV) remains a leading cause of liver disease worldwide. Given that many countries continue to experience high rates of transmission despite the availability of potent antiviral therapies, an effective vaccine is seen as critical for the elimination of HCV. The recent failure of the first vaccine efficacy trial for the prevention of chronic HCV confirmed suspicions that this virus will be a challenging vaccine target. Here, we examine the published data from this first efficacy trial along with the earlier clinical and pre-clinical studies of the vaccine candidate and then discuss three key research directions expected to be important in ongoing and future HCV vaccine development. These include the following: 1. design of novel immunogens that generate immune responses to genetically diverse HCV genotypes and subtypes, 2. strategies to elicit broadly neutralizing antibodies against envelope glycoproteins in addition to cytotoxic and helper T cell responses, and 3. consideration of the unique immunological status of individuals most at risk for HCV infection, including those who inject drugs, in vaccine platform development and early immunogenicity trials.
... Highly effective direct-acting antiviral (DAA) therapy has revolutionized the management of chronic HCV [13], with standard cure rates exceeding 95% [14]. Multiple groups have shown that following IFN-free DAA therapy, there may be partial restoration of both innate and adaptive immune homeostasis [3,[15][16][17][18]. ...
Chronic infection with HCV is manifested by dysregulation of innate immune responses and impaired T cell function at multiple levels. These changes may impact susceptibility to other infections, responsiveness to antiviral therapies, vaccine responsiveness, and development of complications such as hepatocellular carcinoma. Highly effective direct-acting antiviral (DAA) therapy has revolutionized the management of chronic HCV, with expected cure rates exceeding 95%. DAA treatment represents a unique opportunity to investigate to what extent elimination of viral replication and chronic antigen stimulation can restore immunologic phenotype. In this study we interrogated the global transcriptional profile of isolated peripheral blood T cells before, during and after IFN-free DAA therapy using single-cell mRNA sequencing. Our results demonstrate that T cells mapped at single-cell resolution have dramatic transcriptomic changes early after initiation of DAA and many of these changes are sustained after completion of DAA therapy. Specifically, we see a significant reduction in transcripts associated with innate immune activation and interferon signaling such as ISG15 , ISG20 , IFIT3 , OAS and MX1 in many different T cell subsets. Furthermore, we find an early upregulation of a gene involved in suppression of immune activation, DUSP1 , in circulating T cells. Conclusion : This study provides the first in-depth transcriptomic analysis at the single-cell level of patients undergoing DAA therapy, demonstrating that IFN-free antiviral therapy in chronic HCV infection induces hitherto unrecognized shifts in innate immune and interferon signaling within T cell populations early, during, and long-term after treatment. The present study provides a rich data source to explore the effects of DAA treatment on bulk T cells.
... Additionally, HCV is the first, and so far only, chronic viral infection that can be completely terminated using direct-acting antivirals (DAAs) 26 , enabling the study of whether termination of antigen exposure enables the redifferentiation of T EX cell populations into effective T cell memory. Such work has revealed important insights, including T cell proliferation recovery after antigen clearance in parallel to the expansion of preexisting CD127 + PD-1 + TCF-1 + memory-like T cells 27,28 . Nevertheless, these memory-like CD8 + T cells are partially different from actual T MEM cells after acute infection 27,29,30 , indicating the need for more detailed analyses to understand the molecular trajectories of T EX cells after antigen removal and the hurdles to achieving full memory potential. ...
T cell exhaustion is associated with failure to clear chronic infections and malignant cells. Defining the molecular mechanisms of T cell exhaustion and reinvigoration is essential to improving immunotherapeutic modalities. Here we confirmed pervasive phenotypic, functional and transcriptional differences between memory and exhausted antigen-specific CD8⁺ T cells in human hepatitis C virus (HCV) infection before and after treatment. After viral cure, phenotypic changes in clonally stable exhausted T cell populations suggested differentiation toward a memory-like profile. However, functionally, the cells showed little improvement, and critical transcriptional regulators remained in the exhaustion state. Notably, T cells from chronic HCV infection that were exposed to antigen for less time because of viral escape mutations were functionally and transcriptionally more similar to memory T cells from spontaneously resolved HCV infection. Thus, the duration of T cell stimulation impacts exhaustion recovery, with antigen removal after long-term exhaustion being insufficient for the development of functional T cell memory.
... 21 DAA-induced viral clearance was presumed to restore immune response by downregulation of negative costimulatory molecules, an increase in T cell count, and restoration of cytolytic activity. 22 We found a significant reduction in serum IL-10 levels in both cirrhotic and noncirrhotic groups. Saraiva et al. 16 also found a significant reduction in IL-10 levels 12 weeks posttreatment and a significant rise in IFN-gamma, but they did not study the changes during therapy or the changes of each molecule in cirrhotics and noncirrhotics. ...
Introduction
This study analyzes the changing levels of circulating inflammatory cytokines Interferon-gamma and IL-10 (as the main cytokines of T-helper-1 and T-helper-2 immune responses) in patients with chronic hepatitis C virus (HCV) infection undergoing therapy with direct-acting antivirals (DAA) and to correlate them with laboratory markers.
Methods
This Pilot study included 50 HCV mono-infected patients who received DAAs for 12 or 24 weeks. They were followed-up monthly during therapy and three months after the end of treatment. Liver disease was determined by transient elastography, in addition to FIB-4 indexes. Analysis of IFN- gamma and IL-10 was carried out using enzyme-linked immunosorbent assay.
Results
All patients carried HCV genotype-4. Sustained virological response was 100% and 92% in cirrhotics and non-cirrhotics respectively. No significant difference between groups in baseline IL-10 or IFN-gamma. In non-cirrhotics, IL-10 showed a significant reduction at week-4 after treatment start. In cirrhotics, IL-10 showed a significant reduction at week-4 after treatment start and a significant reduction at week-12 after the end of treatment. At week-12 after the end of treatment, Serum IL-10 levels were significantly lower in cirrhotics. IFN-γ showed non-significant changes in non-cirrhotics. A significant increase of IFN-γ occurred in cirrhotics from week 4 after treatment start to 12 weeks after the end of treatment. IFN-γ was significantly higher in cirrhotics at week 12 after the end of treatment. IFN-γ and IL-10 showed different correlations with laboratory markers.
Conclusion
Viral eradication induced by DAAs caused a significant change in IL-10 and IFN-gamma.
... While the viral loads of HCV drop rapidly upon treatment, immune functions appear to be restored only partially. For example, the proliferative capacity of HCV-specific CD8 + T cells is restored 158 but mitochondrial alterations persist over time 159 . Along the same lines, the levels of many, but not all, soluble inflammatory serum proteins that are altered in chronic HCV are normalized upon viral clearance 160 . ...
Natural killer (NK) cells play an important role in innate immune responses to viral infections. Here, we review recent insights into the role of NK cells in viral infections, with particular emphasis on human studies. We first discuss NK cells in the context of acute viral infections, with flavivirus and influenza virus infections as examples. Questions related to activation of NK cells, homing to infected tissues and the role of tissue-resident NK cells in acute viral infections are also addressed. Next, we discuss NK cells in the context of chronic viral infections with hepatitis C virus and HIV-1. Also covered is the role of adaptive-like NK cell expansions as well as the appearance of CD56− NK cells in the course of chronic infection. Specific emphasis is then placed in viral infections in patients with primary immunodeficiencies affecting NK cells. Not least, studies in this area have revealed an important role for NK cells in controlling several herpesvirus infections. Finally, we address new data with respect to the activation of NK cells and NK cell function in humans infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) giving rise to coronavirus disease 2019 (COVID-19). This Review covers the role of natural killer cells in acute and chronic viral infections, with emphasis on human infections and insights from patients with primary immunodeficiencies affecting natural killer cells. It also describes the emerging data on how natural killer cells are involved in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
... The pathogenesis involved in HCC recurrence includes: 1. immune cell dysfunction; 2. change in immune cytokine network; 3. activation of angiogenesis [91]. The dysfunction of mucosal associated invariant T (MAIT) and natural killer (NK) cells, sustained immune suppression by regulatory T cells (Treg) as well as myeloid-derived suppressor cells (MDSCs), changes in the immune cytokine network (TNF-α, IL-6, IL-10, or transforming growth factor (TGF-beta)), increased expression of inhibitory molecules (programmed cell death protein 1(PD-1), cytotoxic T-Lymphocyte antigen 4 (CTLA-4)), and the activation of angiogenesis may inhibit tumor cytolysis and lead to the re-emergence of HCC during or after DAA treatment (Figure 2) [92][93][94][95][96][97][98][99][100][101]. Epigenetic changes such as H3K27ac modifications, exosomal miRNA expression of miR-211-3p, 6826-3p, 1236-3p, and 4448, and the increase of vascular endothelial growth factor (VEGF) and angiopoietin-2 levels after DAA treatment have also been reported to increase HCC recurrence risk [102][103][104]. ...
Simple Summary
Hepatocellular carcinoma (HCC) recurrence is the major obstacle concerning patients’ survival. Tertiary prevention by antiviral therapies could reduce HCC recurrence rate in both chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infected patients. In chronic hepatitis B (CHB) patients, nucleos(t)ide analogues (Nuc) provide a more effective HCC tertiary prevention effect than an interferon (IFN)-based regimen. In chronic hepatitis C (CHC) patients, the tertiary prevention effect by direct acting antiviral agents (DAAs) was reported non-inferior to that by IFN-based therapy. Chronic hepatitis C patients left untreated had the worst survival benefit as well as shorted recurrence-free interval than those treated by either type of antiviral regimen. Although the risk of HCC recurrence could only be decreased but not diminished by antiviral therapies due to host and microenvironmental factors beyond virus infection, antiviral therapy helps to preserve and improve liver function which makes multi-modality anticancer treatment feasible to improve survival.
Abstract
Hepatocellular carcinoma (HCC) ranks as a leading cause of common cancer and cancer-related death. The major etiology of HCC is due to chronic hepatitis virus including HBV and HCV infections. Scheduled HCC surveillance in high risk populations improves the early detection rate and the feasibility of curative treatment. However, high HCC recurrence rate still accounts for the poor prognosis of HCC patients. In this article, we critically review the pathogenesis of viral hepatitis-related hepatocellular carcinoma and the evidence of tertiary prevention efficacy by current available antiviral treatment, and discuss the knowledge gap in viral hepatitis-related HCC tertiary prevention.
... Discrepancies between our observations and those in murine models could be explained by intrinsic differences in murine and human exhausted T cells' potential for functional reinvigoration. Improved antigenspecific T cell function has been associated with antigen clearance in humans with hepatitis C infection treated with direct-acting antiviral therapies (62)(63)(64)(65)(66). Similarly, an immunomodulatory effect of dasatinib on T cells has been associated with improved antitumor immunity (67,68), and BRAF and MEK inhibition in patients with melanoma leads to up-regulation of TCF7 and expansion of melanoma-specific tumor-infiltrating lymphocyte (TIL) (69). ...
CAR-T cells rest to get back in the race
Chimeric antigen receptor (CAR)–T cells, which are engineered to target specific tumor antigens, are increasingly used as an immunotherapy. CAR-T cells have shown promising results in patients, particularly in hematologic cancers, but their anticancer activity can be limited by the onset of exhaustion and the loss of effectiveness. Weber et al. characterized the phenotypic and epigenomic changes associated with CAR-T cell exhaustion caused by continuous activity and the beneficial effects of transient rest periods (see the Perspective by Mamonkin and Brenner). The authors tested different approaches for providing these rest periods, such as using the drug dasatinib to temporarily suppress T cell activity, which helped to prevent exhaustion and improved antitumor activity in mouse models.
Science , this issue p. eaba1786 ; see also p. 34
... The approval of DAA therapy not only revolutionized patient care but also provides a unique chance to study CD8 + T cell impairment by T cell exhaustion in a clinically relevant setting. By taking this opportunity, recent studies [51,60,75,109,110] underlined the relevant role of ongoing antigen recognition in driving HCV-specific CD8 + T cell exhaustion and offered novel insights into phenotypic and functional heterogeneity, metabolic dysregulation and fate of exhausted CD8 + T cells during and after cHCV infection. Although there is some data available regarding CD8 + T cell exhaustion in HCC [7,101] much less is understood concerning mechanistic details due to the absence of knowledge about the targeted antigens. ...
Chronic hepatitis C virus (cHCV) infection is a major global health burden and the leading cause of hepatocellular carcinoma (HCC) in the Western world. The course and outcome of HCV infection is centrally influenced by CD8+ T cell responses. Indeed, strong virus-specific CD8+ T cell responses are associated with spontaneous viral clearance while failure of these responses, e.g., caused by viral escape and T cell exhaustion, is associated with the development of chronic infection. Recently, heterogeneity within the exhausted HCV-specific CD8+ T cells has been observed with implications for immunotherapeutic approaches also for other diseases. In HCC, the presence of tumor-infiltrating and peripheral CD8+ T cell responses correlates with a favorable prognosis. Thus, tumor-associated and tumor-specific CD8+ T cells are considered suitable targets for immunotherapeutic strategies. Here, we review the current knowledge of CD8+ T cell responses in chronic HCV infection and HCC and their respective failure with the potential consequences for T cell-associated immunotherapeutic approaches.
... Viral escape mutations frequently occur within HCV epitopes targeted by CD8 + T cells leading to diminished or even abrogated recognition. Both the course of infection and the emergence of viral sequence mutations impact the virus-specific CD8 + T cell response [21][22][23][24][25][26][27][28] . To analyze whether the emergence of T ML/HCV cells is associated with the course of HCV infection and ongoing antigen recognition (Fig. 1a), we compared the frequency of T ML/HCV cells in individuals with cHCV (all infected with HCV genotype 1 and non-cirrhotic), cured HCV (all after successful DAA treatment and non-cirrhotic) and rHCV. ...
In chronic hepatitis C virus (HCV) infection, exhausted HCV-specific CD8⁺ T cells comprise memory-like and terminally exhausted subsets. However, little is known about the molecular profile and fate of these two subsets after the elimination of chronic antigen stimulation by direct-acting antiviral (DAA) therapy. Here, we report a progenitor–progeny relationship between memory-like and terminally exhausted HCV-specific CD8⁺ T cells via an intermediate subset. Single-cell transcriptomics implicated that memory-like cells are maintained and terminally exhausted cells are lost after DAA-mediated cure, resulting in a memory polarization of the overall HCV-specific CD8⁺ T cell response. However, an exhausted core signature of memory-like CD8⁺ T cells was still detectable, including, to a smaller extent, in HCV-specific CD8⁺ T cells targeting variant epitopes. These results identify a molecular signature of T cell exhaustion that is maintained as a chronic scar in HCV-specific CD8⁺ T cells even after the cessation of chronic antigen stimulation.
... Immune cell dysfunction: Initial data regarding the T-cell function were published in 2014 during and after direct-acting antiviral therapy 14 .In 51 previously untreated and chronically infected patients receiving DAAS therapy, treatment the researchers analyzed virus-specific CD8+ T cells and in patients receiving SVR within 4 weeks of treatment, the frequency of HCV-specific CD8 + T cells increased significantly, whereas there are no alterations in patients with therapeutic failure were observed. Result of infection with HCV revealed reversible immune dysfunction and that even short treatment was able to restore immune capacity with novel DAAs. ...
Background: Infection with hepatitis C poses a global health problem that affects 200 million chronically infected patients globally. Infected patients with hepatitis C virus (HCV) run a high risk of developing fibrosis, cirrhosis and hepatocellular carcinoma. Aim of work: to evaluate the occurrence of hepatocellular carcinoma (HCC) in DAA-treated patients with chronic hepatitis C (CHC). Patient and Methods: The research involved 500 DAAS-treated patients who had chronic viral hepatitis C. We carried out this retrospective study at Al-Azhar University, Department of Internal Medicine and Hepatology Unit, Ahmed Maher Teaching Hospital. The protocol to the research was accepted by both centers' local ethical committee. Results: The end of treatment regarding the basic data revealed that HCC patients were significantly older. In spite of the fact that HCC patients in the present study comprised higher frequency of males, the difference between those patients and patients without HCC fell short of statistical significance. In our study, all patients with elevated AFP at the end of treatment developed HCC. Conclusion: In relation to the various demographic, clinical and laboratory data, hepatocellular carcinoma patients were found to be significantly older when compared with other patients. All chronic hepatitis C patients with elevated alpha-fetoprotein at the end of treatment developed hepatocellular carcinoma.Older HCC-risk patients should be carefully monitored.
... So far relatively few studies reported on the effects of treatment-induced HCV elimination on the immune exhaustion status of T-cells, and especially on HCV-specific cells. Furthermore, these studies were often inconclusive, carried out on small cohorts of patients infected with various HCV genotypes, assessed different immunological parameters, confined to the analysis of only one inhibitory T-cell receptor, or were conducted on patients treated with IFN or even experimental drugs, which were eventually abandoned [47][48][49][50][51][52][53][54] . The current standard of care of chronic HCV infection advocates the use of DAA, which are successful in over 95% of patients 55 . ...
During chronic hepatitis C virus (HCV) infection, both CD4$^{+}$ and CD8$^{+}$ T-cells become functionally exhausted, which is reflected by increased expression of programmed cell death-1 (PD-1) and T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3), and elevated anti-inflammatory interleukin 10 (IL-10) plasma levels. We studied 76 DAA-treated HCV-positive patients and 18 non-infected controls. Flow cytometry measured pretreatment frequencies of CD4$^{+}$PD-1$^{+}$, CD4$^{+}$PD-1$^{+}$Tim-3$^{+}$ and CD8$^{+}$PD-1$^{+}$Tim-3$^{+}$ T-cells and IL-10 levels measured by ELISA were significantly higher and CD4$^{+}$PD-1$^{-}$Tim-3$^{-}$ and CD8$^{+}$PD-1$^{-}$Tim-3$^{-}$ T-cells were significantly lower in patients than in controls. Treatment resulted in significant decrease of CD4$^{+}$Tim-3$^{+}$, CD8$^{+}$Tim-3$^{+}$, CD4$^{+}$PD-1$^{+}$Tim-3$^{+}$ and CD8$^{+}$PD-1$^{+}$Tim-3$^{+}$ T-cell frequencies as well as IL-10 levels and increase in CD4$^{+}$PD-1$^{-}$Tim-3$^{-}$ and CD8$^{+}$PD-1$^{-}$Tim-3$^{-}$ T-cells. There were no significant changes in the frequencies of CD4$^{+}$PD-1$^{+}$ T-cells, while CD8$^{+}$PD-1$^{+}$ T-cells increased. Patients with advanced liver fibrosis had higher PD-1 and lower Tim-3 expression on CD4$^{+}$T-cells and treatment had little or no effect on the exhaustion markers. HCV-specific CD8$^{+}$T-cells frequency has declined significantly after treatment, but their PD-1 and Tim-3 expression did not change. Successful treatment of chronic hepatitis C with DAA is associated with reversal of immune exhaustion phenotype, but this effect is absent in patients with advanced liver fibrosis.
... In patients successfully treated with IFN-free therapy, a restoration of the proliferative capacity of these HCV-specific CD8 1 T cells has been observed. (34) However, whether the function of these HCV-specific CD8 1 T cells also improves is unknown, as is whether restoration of HCV immunity could contribute to HCV viral control. We therefore analyzed HCV-specific CD8 1 T cells in RG-101-dosed patients, and we did not observe an increase in the ex vivo magnitude of HCV-specific CD8 1 T cells as measured by HLA-A2-restricted multimers. ...
MicroRNA‐122 is an important host factor for the hepatitis C virus (HCV). Treatment with RG‐101, an N‐acetylgalactosamine‐conjugated anti‐microRNA‐122 oligonucleotide, resulted in a significant viral load reduction in patients with chronic HCV infection. Here, we analyzed the effects of RG‐101 therapy on antiviral immunity. Thirty‐two chronic HCV patients infected with HCV genotypes 1, 3, and 4 received a single subcutaneous administration of RG‐101 at 2 mg/kg (n = 14) or 4 mg/kg (n = 14) or received a placebo (n = 2/dosing group). Plasma and peripheral blood mononuclear cells were collected at multiple time points, and comprehensive immunological analyses were performed. Following RG‐101 administration, HCV RNA declined in all patients (mean decline at week 2, 3.27 log10 IU/mL). At week 8 HCV RNA was undetectable in 15/28 patients. Plasma interferon‐γ‐induced protein 10 (IP‐10) levels declined significantly upon dosing with RG‐101. Furthermore, the frequency of natural killer (NK) cells increased, the proportion of NK cells expressing activating receptors normalized, and NK cell interferon‐γ production decreased after RG‐101 dosing. Functional HCV‐specific interferon‐γ T‐cell responses did not significantly change in patients who had undetectable HCV RNA levels by week 8 post–RG‐101 injection. No increase in the magnitude of HCV‐specific T‐cell responses was observed at later time points, including 3 patients who were HCV RNA–negative 76 weeks postdosing. Conclusion: Dosing with RG‐101 is associated with a restoration of NK‐cell proportions and a decrease of NK cells expressing activation receptors; however, the magnitude and functionality of ex vivo HCV‐specific T‐cell responses did not increase following RG‐101 injection, suggesting that NK cells, but not HCV adaptive immunity, may contribute to HCV viral control following RG‐101 therapy.
The hepatitis C virus (HCV) infection affects 58 million people worldwide. In the United States, the incidence rate of acute hepatitis C has doubled since 2014; during 2021, this increased to 5% from 2020. Acute hepatitis C is defined by any symptom of acute viral hepatitis plus either jaundice or elevated serum alanine aminotransferase (ALT) activity with the detection of HCV RNA, the anti-HCV antibody, or hepatitis C virus antigen(s). However, most patients with acute infection are asymptomatic. In addition, ALT activity and HCV RNA levels can fluctuate, and a delayed detection of the anti-HCV antibody can occur among some immunocompromised persons with HCV infection. The detection of specific biomarkers can be of great value in the early detection of HCV infection at an asymptomatic stage. The high rate of HCV replication (which is approximately 1010 to 1012 virions per day) and the lack of proofreading by the viral RNA polymerase leads to enormous genetic diversity, creating a major challenge for the host immune response. This broad genetic diversity contributes to the likelihood of developing chronic infection, thus leading to the development of cirrhosis and liver cancer. Direct-acting antiviral (DAA) therapies for HCV infection are highly effective with a cure rate of up to 99%. At the same time, many patients with HCV infection are unaware of their infection status because of the mostly asymptomatic nature of hepatitis C, so they remain undiagnosed until the liver damage has advanced. Molecular mechanisms induced by HCV have been intensely investigated to find biomarkers for diagnosing the acute and chronic phases of the infection. However, there are no clinically verified biomarkers for patients with hepatitis C. In this review, we discuss the biomarkers that can differentiate acute from chronic hepatitis C, and we summarize the current state of the literature on the useful biomarkers that are detectable during acute and chronic HCV infection, liver fibrosis/cirrhosis, and hepatocellular carcinoma (HCC).
Chronic hepatitis C virus (HCV) infection induces interferon and dysregulates immune responses through inflammation and chronic antigenic stimulation. Antiviral drugs can cure HCV, providing a unique opportunity to examine the immunological restoration that does and does not occur when a chronic viral infection is eradicated. We quantified blood cytokines levels and used mass cytometry to immunophenotype peripheral blood mononuclear cells (PBMCs) before and after HCV cure in two groups of patients and controls. At baseline, serum IFNα and sCD163 (a macrophage product) were elevated in both liver transplant and non-liver transplant patients compared to controls; the frequencies of several PBMC populations differed from controls; and PD- positivity was increased in nearly all T cell subsets. Many abnormalities persisted after HCV cure, including elevated PD-1 expression on CD4 naïve and central memory T cells, elevated sCD163, and expansion of the plasmablast/plasma cell compartment. Several myeloid lineage subsets, including antigen presenting dendritic cells, remained dysregulated. In mechanistic studies, IFNα treatment increased PD-1 on human T cells and increased T cell receptor signaling. The data identify immunological abnormalities that persist after curative HCV treatment. Prior to cure, high levels of IFNα may stimulate PD-1 expression on human T cells, causing persistent functional changes.
Hepatitis C virus (HCV) infection provides a unique opportunity to study the effects of spontaneous or treatment-induced viral elimination on the human immune system. Twenty to 50% of patients with acute HCV infection spontaneously clear the virus, which is related to the quality of the individual's immune response, while the chronic infection is associated with an altered and impaired immune response. Direct-acting antiviral agents are now available that provide sustained viral elimination in more than 95% of patients with chronic HCV infection. Viral elimination leads to a decrease in disease sequelae such as cirrhosis and hepatocellular carcinoma, and extrahepatic manifestations also improve. However, some patients may still experience long-term complications, and viral elimination does not protect against HCV reinfection. This review addresses the question of whether the altered and impaired immune response caused by HCV normalizes after viral elimination and if this may affect the long-term clinical course after HCV cure.
Background: Immunopathology is responsible for clinical sequelae of chronic HCV infection, FoxP3 + CD25 high CD4 + regulatory T cells (Tregs) are the master regulators of several immune functions and monitoring their dynamics during HCV infection and after viral clearance is of great importance. Objective: to investigate alterations in FoxP3 + CD25 high CD4 + Treg cells frequency and their FoxP3 expression level in chronic HCV infected Egyptian patients undergoing interferon-free direct acting antiviral (DAA) therapy in comparison to healthy controls. Methodology: Twenty chronic HCV patients undergoing sofosbuvir/daclatasvir combination therapy were included, circulating FoxP3 + CD25 high CD4 + Treg cells frequency and their FoxP3 expression were assessed by flow cytometry before and at 2 time points after completing the treatment course, correlated with clinical and radiological data at enrollment and compared to those of 20 healthy anti-HCV negative blood donors. Results: Circulating FoxP3 + CD25 high CD4 + Treg cells frequency and their FoxP3 expression were significantly elevated in chronic HCV patients before treatment with no correlation to virus load, ALT level or fibrosis grade. Treg parameters falls significantly after sofosbuvir/daclatasvir therapy. Treg frequency remained significantly higher than controls 6 months after treatment. Conclusion: DAA therapy was effective at reducing Treg cells frequency and FoxP3 expression but the persistent higher level than normal after 6 months of viral eradication should be further investigated to find out when they will normalize and their influence on the future course of the disease.
The burden of hepatitis C virus infection on the public health care system continues to remain significant despite the remarkable progresses made in HCV therapeutics in the recent past. There are now almost a dozen oral interferon-free direct-acting antivirals available for the treatment of hepatitis C virus infection. Despite advances in the treatment of HCV, therapeutic gaps remain that are yet to be fully explored, researchers and scientists still strive to understand virus-host interactions to map the disease's progression; extrahepatic manifestations and virus invasion strategies impacting the host's immune system. This book briefly discusses the biology of HCV infection, virus-host interactions, molecular epidemiology of the infection, and the full spectrum of immune responses to hepatitis C. It also provides in-depth information about HCV, clinical diagnostics, and therapeutic knowledge to all stakeholders involved in HCV screening, diagnosis, treatment, and management. Topics covered in chapters include 1) HCV-host interactions leading to asymptomatic acute infection, 2) the progression of acute HCV infection to chronic disease and subsequent extrahepatic comorbidities, 3) Innate and adaptive immune responses in HCV infections, 4) Consensus-based Approaches for Hepatitis C Screening and Diagnosis, 5) advances in hepatitis C therapy and global management of HCV, and 6) the outcomes of Oral Interferon-free Direct-acting Antivirals as Combination Therapies to Cure Hepatitis C. This book would be a valuable addition to undergraduate and postgraduate hepatology students and physicians, clinicians, hepatologists, and health care officials involved in HCV clinical diagnosis and therapeutics.
Individuals who spontaneously clear hepatitis C virus (HCV) infection have demonstrated evidence of partial protective immunity, whereas treatment‐induced clearance provides little or no protection against reinfection. We aimed to investigate whether treatment of acute HCV infection with direct‐acting antivirals (DAA) prevents establishment of, or reverses, T cell exhaustion, leading to a virus‐specific T cell immune profile more similar to that seen in spontaneous clearance. The magnitude and breadth of HCV‐specific T cell responses before and after DAA or interferon‐based therapy in acute or chronic HCV were compared to those of participants with spontaneous clearance of infection, using Enzyme‐linked Immunospot (ELISPOT). PBMCs were available for 55 patients comprising 4 groups: spontaneous clearance (n=17), acute interferon (n=14), acute DAA (n=13) and chronic DAA (n=11). After controlling for sex, the magnitude of post‐treatment HCV‐specific responses after acute DAA treatment was greater than after chronic DAA or acute IFN treatment and similar to those found in spontaneous clearers. However, spontaneous clearers responded to more HCV peptide pools indicating greater breadth of response. In conclusion, early treatment with DAAs may prevent or reverse some degree of immune exhaustion and result in stronger HCV‐specific responses post‐treatment. However, individuals with spontaneous clearance had broader HCV‐specific responses.
Background:
Hepatitis C virus (HCV) reinfection after successful treatment may reduce the benefits of cure among people who inject drugs.
Objective:
To evaluate the rate of HCV reinfection for 3 years after successful treatment among people receiving opioid agonist therapy (OAT).
Design:
A 3-year, long-term, extension study of persons enrolled in the CO-STAR (Hepatitis C Patients on Opioid Substitution Therapy Antiviral Response) study (ClinicalTrials.gov: NCT02105688).
Setting:
55 clinical trial sites in 13 countries.
Patients:
Aged 18 years and older with chronic HCV infection with genotypes 1, 4, or 6 receiving stable OAT.
Intervention:
No treatments were administered.
Measurements:
Serum samples were assessed for HCV reinfection. Urine drug screening was performed.
Results:
Among 296 participants who received treatment, 286 were evaluable for reinfection and 199 were enrolled in the long-term extension study. The rate of HCV reinfection was 1.7 [95% CI, 0.8 to 3.0] per 100 person-years; 604 person-years of follow-up). A higher rate of reinfection was seen among people with recent injecting drug use (1.9 [95% CI, 0.5 to 4.8] per 100 person-years; 212 person-years). Ongoing drug use and injecting drug use were reported by 59% and 21% of participants, respectively, at the 6-month follow-up visit and remained stable during 3 years of follow-up.
Limitations:
Participants were required to be 80% adherent to OAT at baseline and may represent a population with higher stability and lower risk for HCV reinfection. Rate of reinfection may be underestimated because all participants did not continue in the long-term extension study; whether participants who discontinued were at higher risk for reinfection is unknown.
Conclusion:
Reinfection with HCV was low but was highest in the first 24 weeks after treatment completion and among people with ongoing injecting drug use and needle-syringe sharing.
Primary funding source:
Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc.
Background:
kidney transplantation from HCV-viremic donors to uninfected recipients is associated with excellent short-term outcomes. However, HCV viremia might be associated with an increased risk for post-transplant viral complications.
Methods:
We designed a retrospective study of HCV-negative kidney-only transplant recipients between 2018 and 2020. Recipients were grouped into group 1; HCV-negative donors, and group 2; HCV-viremic donors. Patients were matched 1:1 using propensity score. Primary objectives were to compare the incidence of CMV viremia ≥ 200 ml/IU, and BK viremia ≥1000 copies/ml between the groups. Secondary outcomes included group comparison of CMV disease, BK viremia ≥10,000 copies/ml, and one year patient and allograft survival.
Results:
The study included 634 patients in group 1, and 71 patients in group 2. 65 pairs of patients were matched. Incidence of CMV viremia (33.3% vs 40.0%, p = 0.4675), and BK viremia (15.9% vs 27.7%, P = 0.1353) did not differ significantly between groups in the matched cohort. Incidence of CMV disease (81.0% Vs 76.9%; p = 1.000), and BK viremia ≥10,000 copies/ml (9.5% vs 16.9%, p = 0.2987) were comparable between groups. There was no difference in the one-year patient or allograft survival between groups.
Conclusion:
kidney transplant from HCV-viremic donors is not associated with increased risk for BK or CMV viremia. This article is protected by copyright. All rights reserved.
Hepatocellular carcinoma (HCC) is an important health problem around the world. It represents >85% of primary liver cancers worldwide. Chronic hepatitis C (CHC) infection is one of the major etiologic factors that cause HCC by producing an inflammatory, fibrogenic, and carcinogenic tissue microenvironment in the liver. In general, HCC develops only after many years of hepatitis C virus (HCV) infection. The increased risk is limited to a great extent to patients with cirrhosis or advanced fibrosis. Given the current prevalence of HCV infection in Middle Eastern countries, the incidence and mortality rates of HCC are likely to increment throughout the following 10 years. Therefore, this chapter reviews the epidemiology, pathogenesis, and risk factors of HCV and HCV-related HCC in the Middle East (ME). Besides, the preventive and treatment strategies of HCV-related HCC are discussed individually. The comprehensive understanding of opportunities and limitations for successfully implementing the World Health Organization (WHO) HCV elimination targets by 2030 in the ME will help to develop strategies and plans tailored to each country’s needs in this region.
Treatment of chronic hepatitis C virus with direct acting antivirals usually eradicates infection, but liver fibrosis does not resolve concurrently. In patients who develop cirrhosis prior to hepatitis C virus treatment, hepatic decompensation and hepatocellular carcinoma can still occur after viral elimination due to residual fibrosis. We hypothesized the liver proteome would exhibit meaningful changes in inflammatory and fibrinogenic pathways change upon hepatitis C virus eradication, which could impact subsequent fibrosis regression. We analyzed the liver proteome and phosphoproteome of paired liver biopsies obtained from 8 hepatitis C virus-infected patients before or immediately after treatment with direct acting antivirals. Proteins in interferon signaling and antiviral pathways decreased concurrent with hepatitis C virus treatment, consistent with prior transcriptomic analyses. Expression of extracellular matrix proteins associated with liver fibrosis did not change with treatment, but the phosphorylation pattern of proteins present within signaling pathways implicated in hepatic fibrinogenesis, including the ERK1/2 pathway, were altered concurrent with hepatitis C virus treatment. Hepatitis C virus treatment leads to reduced expression of hepatic proteins involved in interferon and antiviral signaling. Additionally, changes in fibrosis signaling pathways are detectable before alteration in extracellular matrix proteins, identifying a putative chronology for the dynamic processes involved in fibrosis reversal.
Background & Aims
Cases of acute liver injury (ALI) have been reported among chronic hepatitis C virus-infected initiators of protease inhibitor (PI)-based direct-acting antiviral (DAA) regimens, predominately with decompensated cirrhosis in whom these therapies are contraindicated. No analyses have evaluated if initiators of PI versus non-PI-based DAAs have higher risk of ALI, by advanced hepatic fibrosis/cirrhosis. We compared the risk of three ALI outcomes among PI-based and non-PI-based DAA initiators, by baseline FIB-4.
Methods
We conducted a cohort study of 18,498 initiators of PI-based DAA therapy (paritaprevir/ritonavir/ombitasvir +/- dasabuvir, elbasvir/grazoprevir, glecaprevir/pibrentasvir) matched 1:1 on propensity score to non-PI-based DAA initiators (sofosbuvir/ledipasvir, sofosbuvir/velpatasvir) in the 1945-1965 Veterans Birth Cohort (2014-2019). During exposure to DAA therapy, we determined development of: 1) alanine aminotransferase (ALT) >200 U/L, 2) severe hepatic dysfunction (coagulopathy with hyperbilirubinemia), and 3) hepatic decompensation. We used Cox regression to determine hazard ratios (HRs) with 95% confidence intervals of each ALI outcome in PI versus non-PI initiators within groups defined by baseline FIB-4 (≤3.25; >3.25).
Results
Among persons with baseline FIB-4 ≤3.25, PI initiators had higher risk of ALT >200 U/L (HR, 3.98 [2.37-6.68]), but not severe hepatic dysfunction (HR, 0.67 [0.19-2.39]) or hepatic decompensation (HR, 1.01 [0.29-3.49]), compared to non-PI-initiators. For those with baseline FIB-4 >3.25, PI initiators had higher risk of ALT >200 U/L (HR, 2.15 [1.09-4.26]), but not severe hepatic dysfunction (HR, 1.23 [0.64-2.38]) or hepatic decompensation (HR, 0.87 [0.41-1.87]), compared to non-PI initiators.
Conclusion
While risk of incident ALT elevations was increased among PI-based DAA initiators in both FIB-4 groups, risk of severe hepatic dysfunction and hepatic decompensation did not differ between PI and non-PI-based DAA initiators in either FIB-4 group.
Lay Summary
Cases of liver injury have been reported among patients treated with protease inhibitor-based direct-acting antivirals for hepatitis C infection, but it is not clear if risk of liver injury among people starting these drugs is increased compared to those starting non-protease inhibitor-based therapy. In this study, persons who initiated protease inhibitor-based treatment had higher risk of liver inflammation than non-protease inhibitor-based initiators, regardless of the presence of pre-treatment advanced liver fibrosis/cirrhosis. However, the risk of severe liver dysfunction and decompensation were not higher for protease inhibitor-based initiators.
Recurrence or de novo infection of hepatitis C virus (HCV) after liver‐transplantation has been associated with progressive graft hepatitis that can be improved by treatment with novel direct‐acting antivirals. Cases of rejection episodes have been described during and after HCV treatment. The evolution of innate and adaptive immune response during and after cure of hepatitis C after liver‐transplantation is unknown.
We found that liver‐transplanted patients with active HCV infection displayed distinct alterations of inflammatory protein biomarkers such as CXCL10, CASP‐8, CCL20, CCL19, IFN‐gamma, CDCP1, IL‐18R1, CXCL11, CCL3, IL8, IL12B, TNFB, CXCL6, OPG, IL10, Flt3L, HGF, uPA, NT‐3, CCL4, IL6, TNFRSF9, PD‐L1, IL18 and MCP‐1 and enrichment of peripheral immune cell subsets unlike transplanted patients without HCV infection. Interestingly, patients that cleared HCV post liver‐transplantation did not normalize the altered inflammatory milieu nor did the peripheral immune cell subsets normalize to what would be seen in the absence of HCV recurrence.
Overall, these data indicate that HCV‐specific imprints on inflammatory analytes and immune cell subsets post liver‐transplantation are not completely normalized by therapy‐induced HCV elimination. This is in line with the clinical observation that cure of HCV post‐transplantation did not trigger rejection episodes in many patients.
Hepatitis C virus (HCV) is one of the most endemic pathogens in the world. The virus can cause acute and chronic hepatitis that progresses to liver cirrhosis or hepatocellular carcinoma. HCV utilizes multifaceted strategies to escape from the host surveillance system and submerge under an immunological radar. Pervasive, moderately compromised immune dysfunction, or exhaustion, is a fundamental feature of chronic HCV infection; however, the precise underlying mechanisms remain largely undisclosed. In the era of direct-acting antiviral agents against HCV, success rate of HCV clearance is up to 95%. Nevertheless, in this decade, new cases of HCV or reinfection have significantly increased, especially in the younger generations with high-risk behavior. Comprehensive immunological, virologic, and clinical studies are needed to establish the practical strategy for the prevention of HCV transmission by fostering sustainable protective immunity. To achieve global HCV elimination, the development of the long-awaiting anti-HCV vaccine is urgently warranted.
There is consensus that HCV-specific T cells play a central role in the outcome (clearance vs. persistence) of acute infection and that they contribute to protection against the establishment of persistence after reinfection. However, these T cells often fail and the virus can persist, largely as a result of T cell exhaustion and the emergence of viral escape mutations. Importantly, HCV cure by direct-acting antivirals does not lead to a complete reversion of T cell exhaustion and thus HCV reinfections can occur. The current lack of detailed knowledge about the immunological determinants of viral clearance, persistence and protective immunity is a major roadblock to the development of a prophylactic T cell vaccine. This minireview highlights the basic concepts of successful T cell immunity, major mechanisms of T cell failure and how our understanding of these concepts can be translated into a prophylactic vaccine.
Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections account for 57% of cases of liver cirrhosis and 78% of cases of primary liver cancer worldwide and cause a million deaths per year. Although HBV and HCV differ in their genome structures, replication strategies and life cycles, they have common features, including their noncytopathic nature and their capacity to induce chronic liver disease, which is thought to be immune mediated. However, the rate of disease progression from chronic hepatitis to cirrhosis varies greatly among infected individuals, and the factors that regulate it are largely unknown. This review summarizes our current understanding of the roles of antigen-specific and nonspecific immune cells in the pathogenesis of chronic hepatitis B and C and discusses recent findings that identify natural killer cells as regulators of T cell function and liver inflammation.
Ribavirin improves outcomes of therapy in chronic hepatitis C but its mode of action has still remained unclear. Since ribavirin has been proposed to modulate the host's T cell responses, we studied its direct effects on CD4(+) T cell clones with diverse functional polarization which had been generated from patients with chronic hepatitis C. We analysed in vitro proliferation ([(3)H] thymidine uptake) and cytokine responses (IL-10, IFN-gamma) at varying concentrations of ribavirin (0-10 µg/ml) in 8, 9 and 7 CD4(+) TH1, TH2 and regulatory T cell (Treg) clones, respectively. In co-culture experiments, we further determined effects of ribarivin on inhibition of TH1 and TH2 effector cells by Treg clones. All clones had been generated from peripheral blood of patients with chronic hepatitis C in the presence of HCV core protein. Ribavirin enhanced proliferation of T effector cells and increased production of IFN-gamma in TH1 clones, but had only little effect on IL-10 secretion in TH2 clones. However, ribavirin markedly inhibited IL-10 release in Treg clones in a dose dependent fashion. These Treg clones suppressed proliferation of T effector clones by their IL-10 secretion, and in co-culture assays ribavirin reversed Treg-mediated suppression of T effector cells. Our in vitro data suggest that--in addition to its immunostimulatory effects on TH1 cells--ribavirin can inhibit functions of HCV-specific Tregs and thus reverses Treg-mediated suppression of T effector cells in chronic hepatitis C.
Hepatitis C virus (HCV) persistence is associated with impaired CD8 functions. Whether functional restoration of CD8 T cells chronically exposed to antigen can be obtained once the antigen is removed remains to be clarified.
To determine whether clearance of HCV by antiviral treatment can fully restore the antiviral function of HCV-specific CD8 cells.
Peripheral blood HCV-, Flu- and cytomegalovirus (CMV)-specific CD8 cells were quantified by tetramer staining in 28 patients whose HCV infection resolved after peginterferon or peginterferon/ribavirin treatment for either acute or chronic hepatitis and in eight subjects with acute HCV infection which resolved spontaneously for comparison. HCV-specific CD8 cells were evaluated for their phenotypic and functional characteristics by comparing different patient groups and CD8 cells with different viral specificities in the same patients.
Sustained viral response (SVR) did not lead to full maturation of a functional memory CD8 cell response. In particular, SVR in chronic infection was associated with a greater level of T cell dysfunction than responders after acute infection, who showed HCV-specific CD8 responses comparable to those of spontaneous resolvers but weaker than those of Flu-specific CD8 cells. Higher programmed death (PD)-1 expression was detected on HCV than on Flu- and CMV-specific CD8 cells and the effect of PD-1/PD-L1 blockade was better in SVRs after chronic than after acute HCV infection.
A better restoration of HCV-specific CD8 function was detectable after SVR in patients with acute hepatitis than in those with chronic disease. Thus, the difficulty in achieving a complete restoration of the antiviral T cell function should be considered in the design of immunomodulatory therapies.
Type 1 interferons (IFNs) were the first cytokines discovered and include IFNβ, more than ten forms of IFNα, and several other related molecules that all bind to the same type 1 IFN receptor (IFN1R). Type 1 IFNs are commonly referred to as “viral” IFNs because they can be induced directly by virus infections, in contrast to “immune” IFN, or IFNγ, which is synthesized after receptor engagement of T cells and natural killer (NK) cells during immune responses. Type 1 IFNs get induced by viral nucleic acids and proteins acting on cellular signaling molecules such as Toll-like receptors and RNA helicases, which, in turn, release transcription factors into the nucleus. Mice lacking IFN1R appear normal in a pathogen-free environment but are extraordinarily susceptible to virus infections. This susceptibility is partially due to IFN-regulated genes that suppress viral replication, but type 1 IFNs also have many immunoregulatory properties that could also affect host susceptibility to infection.
We monitored expression of PD-1 (a mediator of T-cell exhaustion and viral persistence) on hepatitis C virus (HCV)-specific
CD8+ and CD4+ T cells from blood and liver during acute and chronic infections and after the resolved infection stage. PD-1 expression
on HCV-specific T cells was high early in acute infection irrespective of clinical outcome, and most cells continued to express
PD-1 in resolved and chronic stages of infection; intrahepatic expression levels were especially high. Our results suggest
that an analysis of PD-1 expression alone is not sufficient to predict infection outcome or to determine T-cell functionality
in HCV infection.
The outcome of viral infections is dependent on the function of CD8+ T cells which are tightly regulated by costimulatory molecules. The NK cell receptor 2B4 (CD244) is a transmembrane protein belonging to the Ig superfamily which can also be expressed by CD8+ T cells. The aim of this study was to analyze the role of 2B4 as an additional costimulatory receptor regulating CD8+ T cell function and in particular to investigate its implication for exhaustion of hepatitis C virus (HCV)-specific CD8+ T cells during persistent infection. We demonstrate that (i) 2B4 is expressed on virus-specific CD8+ T cells during acute and chronic hepatitis C, (ii) that 2B4 cross-linking can lead to both inhibition and activation of HCV-specific CD8+ T cell function, depending on expression levels of 2B4 and the intracellular adaptor molecule SAP and (iii) that 2B4 stimulation may counteract enhanced proliferation of HCV-specific CD8+ T cells induced by PD1 blockade. We suggest that 2B4 is another important molecule within the network of costimulatory/inhibitory receptors regulating CD8+ T cell function in acute and chronic hepatitis C and that 2B4 expression levels could also be a marker of CD8+ T cell dysfunction. Understanding in more detail how 2B4 exerts its differential effects could have implications for the development of novel immunotherapies of HCV infection aiming to achieve immune control.
Vaccine-induced memory is necessary for protective immunity to pathogens, but many viruses induce a state of transient immune suppression that might contribute to the inability of a vaccine to elicit immunity. We evaluated here the fate of bystander T cells activated by third party cognate antigens during acute viral infections in vivo, using distinct models to track and specifically activate HY and P14 transgenic bystander CD8 T cells in vivo during acute arenavirus infections of mice. Viral infections acted as stimulatory adjuvants when bystander T cells were exposed to an inflammatory milieu and cognate antigens at the beginning of infections, but bystander CD8 T cell proliferation in response to cognate antigen was inhibited 3 to 9 days after virus infection. Reduced proliferation was not dependent on Fas-FasL- or tumor necrosis factor (TNF)-induced activation-induced cell death or on deficiencies of antigen presentation. Instead, reduced proliferation was associated with a delayed onset of division that was an intrinsic defect of T cells. Inhibition of proliferation could be simulated by exposure of T cells to the Toll-like receptor agonist and type I interferon (IFN) inducer poly(I · C). T cells lacking IFN-α/β receptors resisted both the suppressive effects of preexposure to poly(I · C) and the stimulatory effects of type I IFN, indicating that the timing of exposure to IFN can have negative or positive effects on T cell proliferation. Inhibition of T cell receptor-stimulated bystander CD8 T cell proliferation during acute viral infections may reflect the reduced ability of vaccines to elicit protective immunity when administered during an acute illness.
Early alpha interferon (IFN-α) therapy against hepatitis C virus (HCV) rescues polyfunctional, virus-specific memory CD8+ T cells, but whether immune restoration is possible during late therapy remains controversial. We compared immune restoration
of HCV-specific memory T cells in patients who cleared HCV infection spontaneously and following early or late IFN therapy.
Multifunctional CD4+ and CD8+ memory T cells were detected in spontaneous resolvers and in individuals treated early following an acute infection. In contrast,
limited responses were detected in patients treated during chronic infection, and the phenotype of HCV-specific cells was
influenced by autologous viral sequences. Our data suggest that irreversible damage to the HCV-specific memory T-cell response
is associated with chronic HCV infection.
Exhausted CD8+ T cell responses during chronic viral infections are defined by a complex expression pattern of inhibitory receptors. However, very little information is currently available about the coexpression patterns of these receptors on human virus-specific CD8+ T cells and their correlation with antiviral functions, T cell differentiation and antigen recognition. We addressed these important aspects in a cohort of 38 chronically HCV infected patients and found a coexpression of inhibitory receptors such as 2B4, CD160 and KLRG1 in association with PD-1 in about half of the HCV-specific CD8+ T cell responses. Importantly, this exhaustive phenotype was associated with low and intermediate levels of CD127 expression, an impaired proliferative capacity, an intermediate T cell differentiation stage and absence of sequence variations within the corresponding epitopes, indicating ongoing antigen triggering. In contrast, a low expression of inhibitory receptors by the remaining HCV-specific CD8+ T cells occurred in concert with a CD127hi phenotype, an early T cell differentiation stage and presence of viral sequence variations within the corresponding epitopes. In sum, these results suggest that T cell exhaustion contributes to the failure of about half of HCV-specific CD8+ T cell responses and that it is determined by a complex interplay of immunological (e.g. T cell differentiation) and virological (e.g. ongoing antigen triggering) factors.
Hepatitis C virus (HCV)-specific CD8+ T cells in persistent HCV infection are low in frequency and paradoxically show a phenotype associated with controlled infections,
expressing the memory marker CD127. We addressed to what extent this phenotype is dependent on the presence of cognate antigen.
We analyzed virus-specific responses in acute and chronic HCV infections and sequenced autologous virus. We show that CD127
expression is associated with decreased antigenic stimulation after either viral clearance or viral variation. Our data indicate
that most CD8 T-cell responses in chronic HCV infection do not target the circulating virus and that the appearance of HCV-specific
CD127+ T cells is driven by viral variation.
A number of emerging molecules and pathways have been implicated in mediating the T-cell exhaustion characteristic of chronic
viral infection. Not all dysfunctional T cells express PD-1, nor are they all rescued by blockade of the PD-1/PD-1 ligand
pathway. In this study, we characterize the expression of T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3)
in chronic hepatitis C infection. For the first time, we found that Tim-3 expression is increased on CD4+ and CD8+ T cells in chronic hepatitis C virus (HCV) infection. The proportion of dually PD-1/Tim-3-expressing cells is greatest in
liver-resident T cells, significantly more so in HCV-specific than in cytomegalovirus-specific cytotoxic T lymphocytes. Tim-3
expression correlates with a dysfunctional and senescent phenotype (CD127low CD57high), a central rather than effector memory profile (CD45RAnegative CCR7high), and reduced Th1/Tc1 cytokine production. We also demonstrate the ability to enhance T-cell proliferation and gamma interferon
production in response to HCV-specific antigens by blocking the Tim-3-Tim-3 ligand interaction. These findings have implications
for the development of novel immunotherapeutic approaches to this common viral infection.
Hepatitis C virus (HCV) is an important human pathogen that represents a model for chronic infection given that the majority of infected individuals fail to clear the infection despite generation of virus-specific T cell responses during the period of acute infection. Although viral sequence evolution at targeted MHC class I-restricted epitopes represents one mechanism for immune escape in HCV, many targeted epitopes remain intact under circumstances of viral persistence. To explore alternative mechanisms of HCV immune evasion, we analyzed patterns of expression of a major inhibitory receptor on T cells, programmed death-1 (PD-1), from the time of initial infection and correlated these with HCV RNA levels, outcome of infection, and sequence escape within the targeted epitope. We show that the level of PD-1 expression in early HCV infection is significantly higher on HCV-specific T cells from subjects who progress to chronic HCV infection than from those who clear infection. This correlation is independent of HCV RNA levels, compatible with the notion that high PD-1 expression on HCV-specific CD8 T cells during acute infection inhibits viral clearance. Viral escape during persistent infection is associated with reduction in PD-1 levels on the surface of HCV-specific T cells, supporting the necessity of ongoing antigenic stimulation of T cells for maintenance of PD-1 expression. These results support the idea that PD-1 expression on T cells specific for nonescaped epitopes contributes to viral persistence and suggest that PD-1 blockade may alter the outcome of HCV infection.
The majority of acute hepatitis C virus (HCV) infections progress to chronicity and progressive liver damage. Alpha interferon (IFN-alpha) antiviral therapy achieves the highest rate of success when IFN-alpha is administered early during the acute phase, but the underlying mechanisms are unknown. We used a panel of major histocompatibility complex class I tetramers to monitor the phenotypic and functional signatures of HCV-specific T cells during acute HCV infection with different infection outcomes and during early IFN therapy. We demonstrate that spontaneous resolution correlates with the early development of polyfunctional (IFN-gamma- and IL-2-producing and CD107a(+)) virus-specific CD8(+) T cells. These polyfunctional T cells are distinguished by the expression of CD127 and Bcl-2 and represent a transitional memory T-cell subset that exhibits the phenotypic and functional signatures of both central and effector memory T cells. In contrast, HCV-specific CD8(+) T cells in acute infections evolving to chronicity expressed low levels of CD127 and Bcl-2, exhibited diminished proliferation and cytokine production, and eventually disappeared from the periphery. Early therapeutic intervention with pegylated IFN-alpha rescued polyfunctional memory T cells expressing high levels of CD127 and Bcl-2. These cells were detectable for up to 1 year following discontinuation of therapy. Our results suggest that the polyfunctionality of HCV-specific T cells can be predictive of the outcome of acute HCV infection and that early therapeutic intervention can reconstitute the pool of long-lived polyfunctional memory T cells.
This study was performed to test the hypothesis that cytotoxic T lymphocyte (CTL) selection of hepatitis C virus (HCV) escape variants plays a role in HCV persistence. The peripheral blood CTL responsiveness of patients with well-established chronic hepatitis C to a panel of 10 prototype HCV peptides (genotype 1a) was compared with the corresponding sequences encoded by the infecting viruses in each patient. Variant viral peptide sequences were threefold more frequent in the presence of a CTL response than in its absence, and CTL responses were detected nearly twice as often in association with variant rather than with prototype viral peptide sequences. Furthermore, over half of the patients were infected with potential CTL escape variants that contained nonimmunogenic and noncross-reactive variant peptides many of which displayed reduced HLA-binding affinity. Surprisingly, follow up analysis over a period of up to 46 mo revealed that, in contrast to the relatively high frequency of escape variants initially observed, the subsequent emergence rate of CTL escape variants was very low. Interestingly, the one escape variant that was detected proved to be a CTL antagonist. Collectively, these observations suggest that CTL selection of epitope variants may have occurred in these patients before their entrance into the study and that it may have played a role in HCV persistence. The low apparent rate of ongoing CTL selection in chronically infected patients, however, suggests that if CTL escape occurs during HCV infection it is probably an early event.
Hepatitis C virus (HCV) readily sets up a persistent infection and is a major cause of liver disease worldwide. Interferon alfa and ribavirin therapy lead to sustained clearance of virus in 31% to 64% of patients with type 1 and non-type 1 genotypes, respectively. It is not clear to what extent these drugs act directly to reduce HCV replication, or indirectly via host immune responses, and what evoked immune responses are associated with clinical outcome. We have examined prospectively 15 patients with chronic HCV infection before, during, and after combination therapy. Quantitative assays for HCV antigen-specific CD4+ and CD8+ T-cell responses, and flow cytometric assays for analysis of the phenotype of T cells, in addition to viral sequencing of core protein, were performed throughout the treatment and follow-up period over 18 months. We found enhancement of proliferative T-cell responses during therapy. Proliferative responses are strikingly heterogeneous in terms of specificity, kinetics, and magnitude. Proliferative responses are often not associated with interferon-gamma release. T-cell responses are rarely sustained irrespective of treatment outcome and this is not due to the evolution of new immune escape variants. T-cell responses tend to peak late in the course of treatment. In conclusion, combination therapy for HCV has a transient effect on host virus-specific T cells in the blood. Induction of sustained T-cell responses may require additional immune modulation later in therapy.
Hepatitis C virus (HCV) infection frequently persists despite substantial virus-specific cellular immune responses. To determine if immunologically driven sequence variation occurs with HCV persistence, we coordinately analyzed sequence evolution and CD8+ T cell responses to epitopes covering the entire HCV polyprotein in subjects who were followed prospectively from before infection to beyond the first year. There were no substitutions in T cell epitopes for a year after infection in a subject who cleared viremia. In contrast, in subjects with persistent viremia and detectable T cell responses, we observed substitutions in 69% of T cell epitopes, and every subject had a substitution in at least one epitope. In addition, amino acid substitutions occurred 13-fold more often within than outside T cell epitopes (P < 0.001, range 5-38). T lymphocyte recognition of 8 of 10 mutant peptides was markedly reduced compared with the initial sequence, indicating viral escape. Of 16 nonenvelope substitutions that occurred outside of known T cell epitopes, 8 represented conversion to consensus (P = 0.015). These findings reveal two distinct mechanisms of sequence evolution involved in HCV persistence: viral escape from CD8+ T cell responses and optimization of replicative capacity.
Interleukin-7 (IL-7) is required for the establishment and maintenance of memory CD4(+) and CD8(+) T lymphocytes, and cells lacking IL-7Ralpha (CD127) demonstrate impaired IL-2 secretion and have a short life-span. Chronic HCV is characterized by T cells that are functionally impaired and exhibit an immature phenotype. To investigate the potential role of IL-7/IL-7Ralpha in the outcome of HCV infection, we used multiparameter flow cytometry to characterize patients with acute infection (n = 24), long-term chronic infection (12) and normal subjects (13). HCV infection per se resulted in downregulation of CD127 on total CD4(+) and CD8(+) T lymphocytes as compared to normal controls. Total expression was lowest in those patients who subsequently developed persistence and intermediate in those patients with acute-resolving infection. This reduction affected both naïve and effector/memory T cells. CD127 correlated phenotypically with upregulation of chemokine receptors CCR7 and CXCR4, expression of the anti-apoptotic molecule B cell leukemia/lymphoma 2 (Bcl-2), and enhanced IL-2 production. In six HLA A2-positive patients, we longitudinally tracked tetramer responses to HCV and CMV epitopes; at baseline, reflecting the expression of CD127 on whole T cell populations, viral-specific CTLs in patients who became chronic demonstrated lower CD127. In conclusion, CD127 is a useful marker of functional CD4(+) and CD8(+) T cells and its expression correlates with virologic outcome of acute HCV. These data provide a mechanistic basis for the observation that CTLs generated in early infection rapidly decline as chronicity is established; CD127 expression should be considered in the design of novel immunotherapeutic approaches.
The majority of people infected with hepatitis C virus (HCV) fail to generate or maintain a T-cell response effective for
viral clearance. Evidence from murine chronic viral infections shows that expression of the coinhibitory molecule PD-1 predicts
CD8+ antiviral T-cell exhaustion and may contribute to inadequate pathogen control. To investigate whether human CD8+ T cells express PD-1 and demonstrate a dysfunctional phenotype during chronic HCV infection, peripheral and intrahepatic
HCV-specific CD8+ T cells were examined. We found that in chronic HCV infection, peripheral HCV-specific T cells express high levels of PD-1
and that blockade of the PD-1/PD-L1 interaction led to an enhanced proliferative capacity. Importantly, intrahepatic HCV-specific
T cells, in contrast to those in the periphery, express not only high levels of PD-1 but also decreased interleukin-7 receptor
alpha (CD127), an exhausted phenotype that was HCV antigen specific and compartmentalized to the liver, the site of viral
replication.
Interferon-free regimens would be a major advance in the treatment of patients with chronic hepatitis C virus (HCV) infection.
In this phase 2b, randomized, open-label trial of faldaprevir (a protease inhibitor) and deleobuvir (a nonnucleoside polymerase inhibitor), we randomly assigned 362 previously untreated patients with HCV genotype 1 infection to one of five groups: faldaprevir at a dose of 120 mg once daily and deleobuvir at a dose of 600 mg three times daily, plus ribavirin, for 16, 28, or 40 weeks (TID16W, TID28W, or TID40W, respectively); faldaprevir at a dose of 120 mg once daily and deleobuvir at a dose of 600 mg twice daily, plus ribavirin, for 28 weeks (BID28W); or faldaprevir at a dose of 120 mg once daily and deleobuvir at a dose of 600 mg three times daily, without ribavirin, for 28 weeks (TID28W-NR). The primary end point was a sustained virologic response 12 weeks after the completion of therapy.
The primary end point was met in 59% of patients in the TID16W group, 59% of patients in the TID28W group, 52% of patients in the TID40W group, 69% of patients in the BID28W group, and 39% of patients in the TID28W-NR group. The sustained virologic response 12 weeks after the completion of therapy did not differ significantly according to treatment duration or dosage among ribavirin-containing regimens. This response was significantly higher with TID28W than with TID28W-NR (P=0.03). Rates of a sustained virologic response 12 weeks after the completion of therapy were 56 to 85% among patients with genotype 1b infection versus 11 to 47% among patients with genotype 1a infection and 58 to 84% among patients with IL28B CC versus 33 to 64% with non-CC genotypes. Rash, photosensitivity, nausea, vomiting, and diarrhea were the most common adverse events.
The rate of a sustained virologic response 12 weeks after the completion of therapy was 52 to 69% among patients who received interferon-free treatment with faldaprevir in combination with deleobuvir plus ribavirin. (Funded by Boehringer Ingelheim; SOUND-C2 ClinicalTrials.gov number, NCT01132313.).
Background & aims:
Dysfunctional CD8(+) T cells are believed to contribute to the ability of hepatitis C virus (HCV) to evade the immune response. Most studies have focused on the effector functions of HCV-specific CD8(+) T cells or their surface expression of inhibitory receptors. There is currently no information available about the ex vivo ability of HCV-specific CD8(+) T cells to inhibit viral replication (antiviral efficacy).
Methods:
To analyze the antiviral efficacy of virus-specific CD8(+) T cells ex vivo, we used an immunologic model based on a cell line that expresses HLA-A*02 and contains a stably replicating HCV reporter replicon. We isolated HCV-specific CD8(+) T cells from 18 HLA-A*02-positive patients with chronic HCV infection and 15 subjects with resolved HCV infection (7 spontaneous, 8 after therapy). Replicon cells were labeled with virus-specific peptides; inhibition of HCV replication was determined by measuring luciferase activity after 72 hours of coculture with virus-specific CD8(+) T cells.
Results:
HCV-specific CD8(+) T cells from patients with chronic HCV infection had a significantly lower antiviral efficacy than influenza-, Epstein-Barr virus-, and cytomegalovirus-specific CD8(+) T cells. Antiviral efficacy was associated with the ability of virus-specific CD8(+) T cells to secrete interferon gamma. The antiviral efficacy of HCV-specific CD8(+) T cells was linked to surface expression of CD127 and PD-1. The cytokines interleukin-2, interleukin-7, and interleukin-15 increased the antiviral efficacy of CD127-positive but not of CD127-negative, HCV-specific CD8(+) T cells. Spontaneous, but not antiviral therapy-induced, viral clearance was associated with increased antiviral efficacy.
Conclusions:
The ability of CD8(+) T cells to inhibit HCV replication ex vivo is associated with their ability to secrete interferon gamma and their surface expression of CD127 and PD-1.
Over recent years, it has become increasingly accepted that virus-specific CD4+ and CD8+ T cell responses play a major role in outcome and pathogenesis of hepatitis C virus (HCV) infection. Indeed, while the emergence of strong and multispecific T cell responses may correlate with spontaneous viral clearance, the virus has developed several mechanisms to avoid T cell control in the majority of acutely HCV-infected patients that subsequently develop persistent HCV infection. In this review, we will discuss the current knowledge about the role of cellular immune responses in HCV infection. Specifically, we will emphasise recent new insights into the effector functions of T cells, possible mechanisms of their failure and the host-virus interactions occurring at the site of the disease, the liver.
Virus-specific CD8+ T cells are required for the control of hepatitis C virus (HCV) infection. We investigated the extent to which different effector functions of CD8+ T cells contribute to the inhibition of viral replication.
We developed a novel immunologic model by stably transducing the HLA-A2 gene into the replicon system, matching the epitope sequence of the replicon to the sequence targeted by an HCV-specific CD8+ T-cell clone. Luciferase activity was then measured to quantitate HCV RNA replication.
HCV-specific CD8+ T cells strongly inhibited viral replication, through cytolytic and noncytolytic mechanisms, in a dose-dependent manner. HCV replication was almost completely inhibited at an effector-to-target ratio of 1:1 with significant cytotoxicity; however, >95% viral inhibition occurred at ratios as low as 1:100. Importantly, no cytotoxicity was observed at low effector-to-target ratios, indicating a dominant effect of noncytolytic effector functions that was confirmed by Transwell experiments. Neutralization experiments revealed that interferon gamma mediates the noncytolytic inhibition.
Only a very few HCV-specific CD8+ T cells are required to inhibit HCV replication; inhibition occurs primarily by noncytolytic effector functions.
A timely, efficient, and coordinated activation of both CD4 and CD8 T cell subsets following HCV infection is believed to be essential for HCV control. However, to what extent a failure of the individual T cell subsets can contribute to the high propensity of HCV to persist is still largely undefined. To address this issue, we analyzed the breadth, vigor, and quality of CD4 and CD8 responses simultaneously with panels of peptides covering the entire HCV sequence or containing the HLA-A2-binding motif, and with recombinant HCV proteins in 16 patients with acute HCV infection by tetramer staining, ELISPOT, and intracellular cytokine staining for interferon gamma, interleukin (IL)-2, IL-4, and IL-10. Our results indicate that at clinical onset, CD8 responses are similarly weak and narrowly focused in both self-limited and chronically evolving infections. At this stage, CD4 responses are deeply impaired in patients with a chronic outcome as they are weak and of narrow specificity, unlike the strong, broad and T helper 1-oriented CD4 responses associated with resolving infections. Only patients able to finally control infection show maturation of CD8 memory sustained by progressive expansion of CD127+ CD8 cells. Thus, a poor CD8 response in the acute stage of infection may enhance the overall probability of chronic viral persistence. In conclusion, the presence of functional CD4 responses represents one of the factors dictating the fate of infection by directly contributing to control of the virus and by promoting maturation of protective memory CD8 responses.
Flow cytometry-based immunophenotyping assays have become increasingly multiparametric, concomitantly analyzing multiple cellular parameters. To maximize the quality of the information obtained, antibody conjugate panels need to be developed with care, including requisite controls at every step. Such an optimization procedure for multicolor immunophenotyping assays is time consuming, but the value of having a reliable antibody conjugate panel that provides for sensitive detection of all molecules of interest justifies this time investment. This article outlines important considerations and procedures to undertake for the successful design and development of multicolor flow cytometry panels.
Unlabelled:
Virus-specific CD8+ T-cells play an important role in the outcome of acute hepatitis C virus (HCV) infection. In the chronic phase, however, HCV can persist despite the presence of virus-specific T-cell responses. Therefore, we set out to perform a full-breadth analysis of the intrahepatic virus-specific CD8+ T-cell response, its relation to the peripheral T-cell response, and the overall influence of viral escape and the genetic restriction on intrahepatic CD8+ T-cell failure. Intrahepatic and peripheral CD8+ T-cells from 20 chronically HCV infected patients (genotype 1) were comprehensively analyzed using overlapping peptides spanning the entire HCV polyprotein in concert with autologous viral sequences that were obtained for all targeted regions. HCV-specific CD8+ T-cell responses were detectable in most (90%) chronically HCV-infected patients, and two thirds of these responses targeted novel previously undescribed epitopes. Most of the responses were detectable only in the liver but not in the peripheral blood, indicating accumulation and enrichment at the site of disease. Of note, only approximately half of the responses were associated with viral sequence variations supported by functional analysis as viral escape mutations. Escape mutations were more often associated with HLA-B alleles.
Conclusion:
Our results show an unexpected high frequency of intrahepatic virus-specific CD8+ T-cells, a large part of which continue to target the present viral antigens. Thus, our results suggest that factors other than mutational escape contribute to the failure of intrahepatic virus-specific CD8+ T-cells.
The immunoinhibitory receptor programmed death-1 (PD-1) is up-regulated on dysfunctional virus-specific CD8 T cells during chronic viral infections, and blockade of PD-1/PD-ligand (PD-L) interactions can restore their function. As hepatitis C virus (HCV) persists in the liver with immune-mediated disease pathogenesis, we examined the role of PD-1/PD-L pathway in antigen-specific CD8 T-cell dysfunction in the liver and blood of HCV-infected patients.
PD-1 expression and function of circulating CD8 T cells specific for HCV, Epstein-Barr virus, and influenza virus were examined ex vivo and following antigenic stimulation in vitro in patients with acute, chronic, and resolved HCV infection using class I tetramers and flow cytometry. Intrahepatic CD8 T cells were examined from liver explants of chronically HCV-infected transplant recipients.
Intrahepatic HCV-specific CD8 T cells from chronically HCV-infected patients were highly PD-1 positive, profoundly dysfunctional, and unexpectedly refractory to PD-1/PD-L blockade, contrasting from circulating PD-1-intermediate HCV-specific CD8 T cells with responsiveness to PD-1/PD-L blockade. This intrahepatic functional impairment was HCV-specific and directly associated with the level of PD-1 expression. Highly PD-1-positive intrahepatic CD8 T cells were more phenotypically exhausted with increased cytotoxic T-lymphocyte antigen 4 and reduced CD28 and CD127 expression, suggesting that active antigen-specific stimulation in the liver induces a profound functional exhaustion not reversible by PD-1/PD-L blockade alone.
HCV-specific CD8 T-cell dysfunction and responsiveness to PD-1/PD-L blockade are defined by their PD-1 expression and compartmentalization. These findings provide new and clinically relevant insight to differential antigen-specific CD8 T-cell exhaustion and their functional restoration.
The HCV-specific HLA-A2-restricted NS3(1073) epitope is one of the most frequently recognized epitopes in hepatitis C. NS3(1073)-specific T-cell responses are associated with clearance of acute HCV-infection. Therefore this epitope is an interesting candidate for a HCV-peptide vaccine. However, heterogeneity between genotypes and mutations in the epitope has to be considered as an obstacle. We here identified 34 naturally occurring NS3(1073)-variants, as compared with the wild type genotype-1 variants (CVNGVCWTV/CINGVCWTV) by sequencing sera of 251 Greek and German patients and searching for published HCV-genomes. The frequency of variants among genotype-1 patients was 10%. Importantly, HLA-A2 binding was reduced only in 3 genotype 1 mutants while all non-genotype 1 variants showed strong HLA-A2-binding. By screening 28 variants in ELISPOT assays from T cell lines we could demonstrate that HCV-NS3(1073)-wild-type-specific T-cells displayed cross-genotype-reactivity, in particular against genotypes 4-6 variants. However, single aa changes within the TCR-binding domain completely abolished recognition even in case of conservative aa exchanges within genotype-1. NS3(1073)-specific T-cell lines from recovered, chronically infected, and HCV-negative individuals showed no major difference in the pattern of cross-recognition although the proliferation of NS3(1073)-specific T-cells differed significantly between the groups. Importantly, the recognition pattern against the 28 variants was also identical directly ex vivo in a patient with acute HCV infection and a healthy volunteer vaccinated with the peptide vaccine IC41 containing the NS3(1073)-wild-type peptide. Thus, partial cross-genotype recognition of HCV NS3(1073)-specific CD8 T cells is possible; however, even single aa exchanges can significantly limit the potential efficacy of vaccines containing the NS3(1073)-wild-type peptide.