[Show abstract][Hide abstract] ABSTRACT: Massive loss of lamina propria CD4(+) T cells, changes in the lymphatic architecture, and altered intestinal epithelial barrier leading to microbial translocation are the common features of HIV-1 infection and are not fully restored under combined antiretroviral therapy (cART). To better understand determinants of gut mucosal restoration, we have performed phenotypic and gene expression analyses of the gut from HIV-infected patients, naive or treated with cART initiated either at the early phase of the primary infection or later during the chronic phase. We found a depletion of T helper type 22 (Th22) and interleukin-17-producing cells in naive patients. These populations, except Th22 cells, were not restored under cART. Regulatory T cells/Th17 ratio was significantly increased in HIV-infected patients and was inversely correlated to the restoration of CD4(+) T cells but not to gut HIV DNA levels. Gene profile analysis of gut mucosal distinguished two groups of patients, which fitted with the timing of cART initiation. In their majority early, but not later treated patients, exhibited conserved intestinal lymphoid structure, epithelial barrier integrity and dendritic cell maturation pathways. Our data demonstrate that early initiation of cART helps to preserve and/or restore lymphoid gut mucosal homeostasis and provide a rationale for initiating cART during the acute phase of HIV infection.Mucosal Immunology advance online publication, 2 July 2014; doi:10.1038/mi.2014.50.
[Show abstract][Hide abstract] ABSTRACT: Human immunodeficiency virus type 1 (HIV-1) infection is characterized by chronic immune activation and suppressed T-lymphocyte
functions. Here we report that CD73, both a coactivator molecule of T cells and an immunosuppressive ecto-enzyme through adenosine
production, is only weakly expressed by CD8+ T cells of HIV-infected patients and only partially restored after successful antiviral treatment. CD73 expression on CD8+ T cells correlates inversely with cell activation both ex vivo and in vitro. However, CD8+ T cells from HIV controllers (HICs), which spontaneously control HIV replication, express CD73 strongly, despite residual
immune activation. Finally, we demonstrate that CD73 is involved in the HIV-specific CD8+ T-cell expansion. Thus, we show that CD73 is central to the functionality of HIV-specific CD8+ T cells and that the preservation of HIV-specific CD73+CD8+ T cells is a characteristic of HICs. These observations reveal a novel mechanism involved in the control of viral replication.
Full-text · Article · Dec 2013 · The Journal of Infectious Diseases
[Show abstract][Hide abstract] ABSTRACT: Author Summary
Regulatory T cells (Treg) represent a subset of T lymphocytes and have a pivotal role in chronic viral infections and cancer by limiting immune activation. It has been shown that Treg are expanded in chronic HIV infected patients. However, the mechanisms of Treg immune-modulator functions are not clearly known. CD39 is an ectonucleotidase which converts the proinflammatory ATP signal into AMP and the immunosuppressive adenosine in concert with another ecto-enzyme CD73. We have previously reported that CD39/adenosine pathway is involved in AIDS progression. However, the mechanism of Treg immunosuppression through CD39 and its involvement in HIV pathogenesis remains unclear. We report here that Treg/CD39+ inhibits the production of IL-2, a cytokine that stimulates the growth of T lymphocytes, via CD39/Adenosine/cAMP enzymatic pathway. The signals induced by adenosine specific receptor A2AR, increase the intra cellular levels of cAMP. We show that cAMP inhibits CpG site demethylation of the il-2 gene promoter. We found that T cells from HIV patients have a higher expression on A2AR as well as intra-cellular cAMP and a lesser capacity to produce IL-2 upon stimulation than healthy subjects. Our results contribute to elucidate the mechanisms by which Treg suppression occurs during HIV infection.
[Show abstract][Hide abstract] ABSTRACT: Author Summary
HIV-1 infection is characterized by a chronic activation of the immune system. Regulatory T cells (Treg) represent a population of lymphocytes that controls inappropriate or exaggerated immune activation induced by pathogens, thereby influencing the outcome of various infections. Several studies have shown that Treg are expanded in HIV infected patients. However, the mechanisms of Treg immune-modulator functions are not clearly known. CD39 is an ectonucleotidase which converts the proinflammatory ATP signal into AMP and the immunosuppressive adenosine in concert with CD73. A critical role of CD39 has been described for Treg in general but few studies have analyzed its role in HIV infection. We report here an expansion of Treg expressing CD39 in a cohort of HIV-infected patients. In vitro these cells exerted a strong suppressive effect on the effector CD8 T cells. Treg inhibitory effects were relieved by CD39 down-modulation using an anti-CD39 monoclonal antibody. Treg suppressive effects were reproduced by an adenosine agonist in accordance with a higher expression of the adenosine A2A receptor on patients' T cells. From a clinical stand point, we show also a correlation between Treg CD39+ expansion and both immune activation and CD4+ T cell depletion in patients. Finally, by genetic analysis of three different cohorts of patients, we found that a CD39 gene polymorphism associated with a lower CD39 expression correlated with a slower progression to AIDS. Thus, our results contribute to elucidate the mechanisms by which Treg suppression occurs during HIV infection.
[Show abstract][Hide abstract] ABSTRACT: Although hepatitis C virus (HCV) can be grown in the hepatocarcinoma-derived cell line Huh-7, a cell-culture model is needed that supports its complete, productive infection cycle in normal, quiescent, highly differentiated human hepatocytes. We sought to develop such a system.
Primary cultures of human adult hepatocytes were inoculated with HCV derived from Huh-7 cell culture (HCVcc) and monitored for expression of hepatocyte differentiation markers and replication of HCV. Culture supernatants were assayed for HCV RNA, core antigen, and infectivity titer. The buoyant densities of input and progeny virus were compared in iodixanol gradients.
While retaining expression of differentiation markers, primary hepatocytes supported the complete infectious cycle of HCV, including production of significant titers of new infectious progeny virus, which was called primary-culture-derived virus (HCVpc). Compared with HCVcc, HCVpc had lower average buoyant density and higher specific infectivity; this was similar to the characteristics of virus particles associated with the very-low-density lipoproteins that are produced during in vivo infection. These properties were lost after re-culture of HCVpc in poorly differentiated Huh-7 cells, suggesting that authentic virions can be produced only by normal hepatocytes that secrete authentic very-low-density lipoproteins.
We have established a cell-culture-based system that allows production of infectious HCV in physiologically relevant human hepatocytes. This provides a useful tool for the study of HCV interactions with its natural host cell and for the development of antiviral therapies.
[Show abstract][Hide abstract] ABSTRACT: HIV-1 infection is characterized by a progressive decline in CD4(+) T cells leading to a state of profound immunodeficiency. IL-2 therapy has been shown to improve CD4(+) counts beyond that observed with antiretroviral therapy. Recent phase III trials revealed that despite a sustained increase in CD4(+) counts, IL-2-treated patients did not experience a better clinical outcome [Abrams D, et al. (2009) N Engl J Med 361(16):1548-1559]. To explain these disappointing results, we have studied phenotypic, functional, and molecular characteristics of CD4(+) T cell populations in IL-2-treated patients. We found that the principal effect of long-term IL-2 therapy was the expansion of two distinct CD4(+)CD25(+) T cell populations (CD4(+)CD25(lo)CD127(lo)FOXP3(+) and CD4(+)CD25(hi)CD127(lo)FOXP3(hi)) that shared phenotypic markers of Treg but could be distinguished by the levels of CD25 and FOXP3 expression. IL-2-expanded CD4(+)CD25(+) T cells suppressed proliferation of effector cells in vitro and had gene expression profiles similar to those of natural regulatory CD4(+)CD25(hi)FOXP3(+) T cells (Treg) from healthy donors, an immunosuppressive T cell subset critically important for the maintenance of self-tolerance. We propose that the sustained increase of the peripheral Treg pool in IL-2-treated HIV patients may account for the unexpected clinical observation that patients with the greatest expansion of CD4(+) T cells had a higher relative risk of clinical progression to AIDS.
Full-text · Article · Jun 2010 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: Alternative, non-invasive techniques are necessary to monitor the progression of liver disease during chronic hepatitis C. Firstly, because serum is the most accessible material for studies using qPCR in microplates, gene transcription was compared in 219 selected genes involved in the pathogenesis of hepatitis C virus (HCV) infection between sera, PBMCs and liver samples collected simultaneously from five patients infected chronically. Secondly, using sera, gene profiles were compared between HCV-infected patients (n = 10) and healthy controls (n = 10). In addition, the influence of alcohol intake was examined in patients infected with HCV genotype-1. Firstly, amplifiable mRNAs were obtained in all samples. After amplification, significant correlations were observed between: liver versus serum; liver versus PBMCs; and serum versus PBMCs (r(2) = 0.37, r(2) = 0.54, r(2) = 0.49, respectively). A comparison of gene transcription by gene involved in T- and B-cell markers, adhesion molecules, apoptosis, liver matrix turnover and inflammation, revealed comparable, significant correlations between serum and liver, (r(2) = 0.30, r(2) = 0.60, r(2) = 0.51, r(2) = 0.51, r(2) = 0.26, and r(2) = 0.61 respectively). Secondly, a quantitative analysis of gene expression in sera between genotype-1b-infected patients and healthy controls revealed that 41 genes involved closely in T-cell activation and apoptosis were over-expressed significantly in patients infected with HCV. In these patients, alcohol consumption was associated with an increased expression of six genes involved in the inflammatory response, together with a decrease of genes associated with dendritic cell function. It is concluded that in patients infected with HCV, serum can be used to evaluate expression of liver genes. Further prospective studies are clearly needed to validate the initial results and to define the relevant genes.
No preview · Article · Mar 2009 · Journal of Medical Virology
[Show abstract][Hide abstract] ABSTRACT: Background and Aim. Primary cultures of human adult hepatocytes provide a relevant model for hepatitis C virus (HCV) natural host cells
but do not support efficient production of progeny virions upon infection with sera from HCV-infected patients. Recently, cell culture
production of infectious virus (HCVcc) has been achieved using the HCV strain JFH1, or chimeras derived thereof, and Huh-7 sublines, but
these transformed cells are only distantly related to differentiated hepatocytes. Here we have used HCVcc to achieve productive infection innormal human adult hepatocytes. Methods. Human hepatocytes isolated from liver resection by collagenase perfusion were seeded at high
density on collagen-coated plates, and then inoculated with HCVcc produced from Huh-7 sublines replicating JFH1 (genotype 2a) or a
genotype 1b-chimera. Cultures were monitored for expression of hepatocyte differentiation markers and replication of HCV genome. Culture
supernatants were examined for HCV core antigen (immunoassay), HCV RNA (standardized viral load assay), and infectivity titer (focus
formation assay). The buoyant densities of input and progeny virions were compared by isopycnic iodixanol gradient ultracentrifugation.
Results. While maintaining expression of differentiation markers, hepatocytes replicated and expressed HCV genome, and produced high
titers of progeny virions (HCVpc) that were infectious for both Huh-7 subline cells and primary human hepatocytes. Antibodies directed to
HCV E1 glycoprotein or to host cell CD81 neutralized infection in a dose-dependent manner. Interestingly, HCVpc had a higher specific
infectivity value (ratio of the infectious titer to the amount of viral RNA) than HCVcc, correlating with a lower average buoyant density.
Conclusions. Collectively, the results show that primary cultures of differentiated human hepatocytes can support the complete life cycle of
HCV, including production of highly infectious low-density particles. This novel system thus provides a relevant model for studying
HCV/host cell interactions and testing candidate antiviral drugs in the context of liver physiology.
[Show abstract][Hide abstract] ABSTRACT: The balanced manifestation of effector functions and the generation of long-living memory cells is a hallmark of efficient CD8(+) T-cell response. Accumulating data pinpoint CD4(+) CD25(high) regulatory T (Treg) cells as a key factor for the inefficiency of CD8(+) T-cell responses in viral persistence. Little is known about the effects of Treg cells on the homeostasis of healthy donor CD8(+) T cells. The present study demonstrates that Treg cells exert differential effects on CD8(+) T-cell subsets. Treg cells inhibited mostly the polyclonal proliferation of CD27(-) effector cells compared with CD27(+) memory CD8(+) T cells. Moreover, they inhibited the polyclonal and antigen-driven differentiation of memory cells into functional effectors as defined by IFN-gamma secretion and induction of CD160 expression. Finally, Treg cells reduced the apoptosis of memory but not of effector and terminal effector cell populations. These effects were at least in part mediated by a decreased expression of PD-L1, but not of programmed death 1 (PD-1), on CD8(+) T cells after activation. Thus, in the setting of a healthy immune system, Treg cells fine-tune the memory/effector cell balance and promote the accumulation of long-living memory cells in case of strong stimulation.
[Show abstract][Hide abstract] ABSTRACT: The detection of negative-strand hepatitis C virus (HCV) RNA is a hallmark of replication. A highly sensitive and specific method is required to quantify the very low level of replication inherent to in vitro infection systems. Based on reverse transcription with a tagged primer in the 5' non-coding region of the HCV genome, followed by a nested PCR with a second round of real-time PCR, a novel method is described with improved sensitivity for negative-strand HCV RNA quantification. The lower detection level was 25 copies per reaction of negative-strand HCV RNA, even in the presence of 1 x 10(5) copies of positive-strand HCV RNA. This protocol was applied to the detection of negative HCV strand RNA in the liver of HCV-infected patients as well as in primary human hepatocytes infected in vitro. In both models, and particularly in each of three, independent in vitro infection experiments, this assay permitted the quantitation of HCV replication.
Full-text · Article · Feb 2007 · Journal of Medical Virology
[Show abstract][Hide abstract] ABSTRACT: Alcohol consumption has a major impact on the natural history of chronic hepatitis C virus (HCV) infection, although the underlying mechanisms are still debated. We designed a clinical study to evaluate the impact of alcohol abuse on both viral load and expression of low-density lipoprotein receptor (LDLR) and CD81 expression. Thirty-eight consecutive HCV-infected patients were enrolled. Group 1 (n = 18), < or =10 g alcohol/day, group 2 (n = 8), < or =30 g alcohol/day, group 3 (n = 12), >or =30 g alcohol/day. Receptors expression was measured by flow cytometry analysis in peripheral blood mononuclear cells (PBMC) and by specific real-time retrotranscription polymerase chain reaction (RT-PCR) in the liver. Serum viral load was evaluated by quantification of both HCV genomic RNA and total core antigen. The hepatic viral load was assessed by real-time RT-PCR. Serum HCV-RNA and total core antigen were significantly correlated, and were higher, albeit not significantly, in group 3 than in group 1. Alcohol consumption had no effect on expression of HCV putative receptors in PBMC, except for CD81, which was upregulated on monocytes in group 2. In the liver, viral load and levels of LDLR transcripts were significantly higher in group 3 than in group 1. Remarkably, a significant positive correlation was found between LDLR transcripts and HCV-RNA (r2 = 0.83, P < 10(-3)). Finally, in vitro experiments suggested that the effect of ethanol on LDLR expression was indirectly mediated by both tumour necrosis factor-alpha and interleukin-1beta. In conclusion, this study is the first to support a role for LDLR in the natural infection by HCV in man.
No preview · Article · Oct 2006 · Journal of Viral Hepatitis