Accumulation of dysfunctional effector CD8+ T cells in the liver of patients with chronic HCV infection.
ABSTRACT Hepatitis C virus (HCV) causes a chronic infection that can lead to fibrosis and carcinoma. Immune responses mediated by cytotoxic T lymphocytes (CTLs) could be involved in viral clearance or persistence, and therefore in determining the course of the disease.
Intrahepatic and peripheral blood CD8+T cells were obtained from 32 HCV-chronically infected patients and analysed by flow-cytometry for surface markers of differentiation, IFNgamma and TNFalpha production, degranulation capacity and perforin content, after CD3 triggering. Results were compared with those obtained from 13 patients with a non-viral liver disease.
Intrahepatic CD8+T cells of HCV-infected patients, despite their phenotype of pre-terminally and terminally differentiated effectors (CCR7-CD45RA-/+), are poorly responsive to T cell receptor (TCR)-mediated stimulation compared with those obtained from uninfected subjects. This defect correlates with the severity of fibrosis, is more pronounced in patients with ALT<1.5xN than with ALT>1.5xNU/ml, and is not evident after mitogen stimulation.
The present study describes the accumulation of hypo-responsive CD8+T cells in the liver of patients with chronic HCV infection. Understanding the mechanisms underlying this impairment may be helpful in the design of innovative strategies for HCV treatment.
- SourceAvailable from: Jacqueline K Flynn[Show abstract] [Hide abstract]
ABSTRACT: The critical events in clearance or persistence of hepatitis C virus (HCV) infection are unknown but likely to be determined early in acute infection. Type 1 and type 2 cytokine production was assessed by HCV peptide ELISpot and multiplex in vitro cytokine production assays in longitudinally collected samples from 20 untreated participants enrolled in the Australian Trial in Acute Hepatitis C (ATAHC); a prospective cohort of acute HCV infection (77% injecting drug users, IDU). Significantly higher interleukin-10 (IL-10) production (P = 0.048), in the relative absence of interferon-gamma (IFN-γ) and IL-2 production, was present early in HCV infection in those who progressed to chronic infection. In contrast, viral clearance was associated with a greater magnitude and broader specificity of IFN-γ (magnitude P < 0.001, breadth P = 0.004) and IL-2 responses, in the relative absence of IL-10. Early IL-10 production was correlated with higher HCV RNA level at baseline (P = 0.046) and week 12 (P = 0.018), while IFN-γ and IL-2 production was inversely correlated with HCV RNA level at baseline (IFN-γ P = 0.020, IL-2 P = 0.050) and week 48 (IFN-γ P = 0.045, IL-2 P = 0.026). Intracellular staining (ICS) indicated the HCV-specific IFN-γ response was primarily from CD8(+) T cells and NK cells, whereas IL-10 production was predominantly from monocytes, with a subset of IL-10 producing CD8(+) T cells present only in those who progressed to chronic infection. IL-10, an immunoregulatory cytokine, appears to play a key role in progression to chronic HCV infection.Journal of Viral Hepatitis 08/2011; 18(8):549-61. · 3.08 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: In hepatitis C virus (HCV) infection, CD8(+) T cell responses have been shown to be important in viral clearance. Examining the efficacy of CD8(+) T cell vaccines against HCV has been limited by the lack of an HCV infectious model in mice and the differences between MHC restriction in humans and mice. Using HLA-A2 transgenic HHD mice, we demonstrate that intranasally delivered Pam2Cys-based lipopeptides containing HLA-A2-restricted HCV epitopes can induce polyfunctional CD8(+) T cell responses in several organs including the liver. To examine the activity of these responses in an infectious context, we developed a recombinant influenza virus that expresses the NS5B(2594-2602) epitope from non-structural protein 5B of hepatitis C virus (PR8-HCV(NS5B)). We showed that mice inoculated with a lipopeptide containing the NS5B epitope had reduced viral loads following challenge with the PR8-HCV(NS5B) virus. This reduction was associated with the induction of NS5B(2594-2602)-specific IFN-γ and TNF-α co-producing CD8(+) T cells. The T cell receptor usage in the NS5B(2594-2602) response was found to exhibit a Vβ8.1/8.2 bias that was characterized by a narrow repertoire and a common CDR3β motif. This work has identified CD8(+) T cell functions induced by lipopeptides that are associated with viral control and demonstrate the potential of lipopeptide-based vaccines as candidates for treatment of HCV infection.Antiviral research 04/2012; 94(2):168-78. · 3.61 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Hepatitis B virus (HBV) persistence is facilitated by exhaustion of CD8 T cells that express the inhibitory receptor programmed cell death-1 (PD-1). Improvement of the HBV-specific T cell function has been obtained in vitro by inhibiting the PD-1/PD-ligand 1 (PD-L1) interaction. In this study, we examined whether in vivo blockade of the PD-1 pathway enhances virus-specific T cell immunity and leads to the resolution of chronic hepadnaviral infection in the woodchuck model. The woodchuck PD-1 was first cloned, characterized, and its expression patterns on T cells from woodchucks with acute or chronic woodchuck hepatitis virus (WHV) infection were investigated. Woodchucks chronically infected with WHV received a combination therapy with nucleoside analogue entecavir (ETV), therapeutic DNA vaccination and woodchuck PD-L1 antibody treatment. The gain of T cell function and the suppression of WHV replication by this therapy were evaluated. We could show that PD-1 expression on CD8 T cells was correlated with WHV viral loads during WHV infection. ETV treatment significantly decreased PD-1 expression on CD8 T cells in chronic carriers. In vivo blockade of PD-1/PD-L1 pathway on CD8 T cells, in combination with ETV treatment and DNA vaccination, potently enhanced the function of virus-specific T cells. Moreover, the combination therapy potently suppressed WHV replication, leading to sustained immunological control of viral infection, anti-WHs antibody development and complete viral clearance in some woodchucks. Our results provide a new approach to improve T cell function in chronic hepatitis B infection, which may be used to design new immunotherapeutic strategies in patients.PLoS Pathogens 01/2014; 10(1):e1003856. · 8.14 Impact Factor