HCV-specific T-cell responses in injecting drug users: evidence for previous exposure to HCV and a role for CD4+ T cells focussing on nonstructural proteins in viral clearance

HCV monoinfection and HIV/HCV coinfection enhance T-cell immune senescence in injecting drug users early during infection

Background

Injecting drug users (IDU) are at premature risk of developing multimorbidity and mortality from causes commonly observed in the elderly. Ageing of the immune system (immune-senescence) can lead to premature morbidity and mortality and can be accelerated by chronic viral infections. Here we investigated the impact of HCV monoinfection and HIV/HCV coinfection on immune parameters in (ex-) IDU. We analyzed telomere length and expression of activation, differentiation and exhaustion markers on T cells at baseline (t = 1) and at follow-up (t = 2) (median interval 16.9 years) in IDU who were: HCV mono-infected (n = 21); HIV/HCV coinfected (n = 23) or multiple exposed but uninfected (MEU) (n = 8).

Results

The median time interval between t = 1 and t = 2 was 16.9 years. Telomere length within CD4⁺ and CD8⁺ T cells decreased significantly over time in all IDU groups (p ≤ 0.012). CD4⁺ T-cell telomere length in HCV mono-infected IDU was significantly reduced compared to healthy donors at t = 1 (p < 0.008). HIV/HCV coinfected IDU had reduced CD4⁺ and CD8⁺ T-cell telomere lengths (p ≤ 0.002) to healthy donors i at t = 1. This was related to persistent levels of immune activation but not due to increased differentiation of T cells over time. Telomere length decrease was observed within all T-cell subsets, but mainly found in immature T cells (CD27⁺CD57⁺) (p ≤ 0.015).

Conclusions

HCV mono-infection and HIV/HCV coinfection enhance T-cell immune-senescence. Our data suggest that this occurred early during infection, which warrants early treatment for both HCV and HIV to reduce immune senescence in later life.

Electronic supplementary material

The online version of this article (doi:10.1186/s12979-016-0065-0) contains supplementary material, which is available to authorized users.

HLA Preferences for Conserved Epitopes: A Potential Mechanism for Hepatitis C Clearance

Hepatitis C virus (HCV) infections affect more than 170 million people worldwide. Most of these individuals are chronically infected, but some clear the infection rapidly. Host factors seem to play a key role in HCV clearance, among them are the human leukocyte antigen (HLA) class I molecules. Certain HLA molecules, e.g., B*27 and B*57, are associated with viral clearance. To identify potential mechanisms for these associations, we assess epitope distribution differences between HLA molecules using experimentally verified and in silico predicted HCV epitopes. Specifically, we show that the NS5B protein harbors the largest fraction of conserved regions among all HCV proteins. Such conserved regions could be good targets for cytotoxic T-cell (CTL) responses. We find that the protective HLA-B*27 molecule preferentially presents cytotoxic T-cell (CTL) epitopes from NS5B and, in general, presents the most strongly conserved epitopes among the 23 HLA molecules analyzed. In contrast, HLA molecules known to be associated with HCV persistence do not have similar preferences and appear to target the variable P7 protein. Overall, our analysis suggests that by targeting highly constrained - and thereby conserved - regions of HCV, the protective HLA molecule HLA-B*27 reduces the ability of HCV to escape the cytotoxic T-cell response of the host. For visualizing the distribution of both experimentally verified and predicted epitopes across the HCV genome, we created the HCV epitope browser, which is available at theory.bio.uu.nl/ucqi/hcv.

Current knowledge and future perspectives on acute hepatitis C infection

Acute hepatitis C virus (HCV) infections are frequently seen worldwide in certain risk groups, with an annual incidence rate varying between 0.08% and 66%. Although this incidence is substantial, a delayed diagnosis during chronic infection is most often made in the absence of clinical symptoms in the acute phase of the infection. Currently used methods to diagnose acute HCV infection are IgG antibody seroconversion and repeated HCV RNA measurements, although no definitive diagnostic test is currently available. Progress in the field of adaptive and innate immune responses has aided both advances in the field of HCV vaccine development and a more basic understanding of viral persistence. The rapid changes in the treatment of chronic HCV infection will affect therapeutic regimens for acute HCV infection in the coming years, leading to shorter treatment courses and pegylated interferon-free modalities. This review gives an overview of the current knowledge and uncertainties, together with some future perspectives on acute hepatitis C epidemiology, virology, immunology, and treatment.

Ongoing risk behavior and the presence of HCV-RNA affect the hepatitis C virus (HCV)-Specific CD4(+) T cell response

The largest population of people at risk for HCV-infection is injecting drug users (DU). We hypothesize that recurrent exposure to HCV, by continuing risk behavior, influences the development of an HCV-specific T-cell response. Therefore, we studied the association between repeated exposure to and the height and focus of the HCV-specific T-cell response in HCV antibody-positive injecting DU (n=18) with ongoing risk behavior ('high-risk'), 9 with and 9 without detectable HCV-RNA), and 9 never-injecting DU ('low-risk', HCV-RNA+). Both total HCV-specific T-cell response, as well as the T-cell response against HCV nonstructural proteins, were significantly higher in injecting compared to never-injecting DU. Interestingly, the high-risk HCV-RNA¯ had no measurable CD4(+) T-cell response to Core protein, compared to detectable responses to Core in the HCV-RNA+ group. Thus, both ongoing risk behavior and presence of HCV-RNA affect the HCV-specific T-cell response in both magnitude and specificity, which may have implications for vaccine development.

TH1 cytokine response to HCV peptides in Egyptian health care workers: a pilot study

Our objective was to elucidate the effects of different HCV peptides on TH1 cytokine synthesis (interleukin 2(IL2), gamma interferon (INFγ) and tumor necrosis factor α (TNF α)), in a proliferative response in a high risk population of HCV seronegative aviremic Egyptian healthcare workers (HCW). We studied the TH1 cytokine response to different HCV peptides among 47 HCW with and without evidence of HCV infection. Participants were classified according to the proliferation index (PI) in a CFSE proliferation assay as an indicator of previous exposure to HCV. Cytokines were analyzed using Luminex xMAP technology. Results showed that positive PI HCW produced a higher IL2 in response to all HCV peptides except NS4, a higher IFNγ response to NS3 and NS4 and no difference in TNFα response when compared to the negative PI HCWs. When compared to chronic HCV HCW, positive PI HCW showed no difference in the IL2 response, a higher IFNγ response to NS4 and NS5 HCV peptides and a higher TNFα response to all peptides. In conclusion the magnitude and type of cytokines produced in HCV infection is critical in determining the outcome of infection. NS4 & NS5 HCV peptides induce a protective TH1 response in positive PI HCW.

Case definitions for acute hepatitis C virus infection: a systematic review

BACKGROUND & AIMS

Case definitions for recent hepatitis C virus (HCV) infection vary considerably between studies. The aim of this systematic review was to characterize case definitions for recent HCV and explore the heterogeneity in studies performed to date.

METHODS

A systematic literature search of MEDLINE, SCOPUS, and ISI Web of Knowledge was performed covering all studies of recent HCV infection cited between January 2000 and June 2011. The criteria used by each study to define cases of recent HCV infection were extracted, structured, and analyzed.

RESULTS

Overall, 195 articles were included, with 87% (n=169) providing a clear case definition for recent HCV infection. The most frequently used individual criteria for defining a case included HCV antibody seroconversion (77%), alanine aminotransferase (ALT) elevation (68%), and HCV RNA detection (63%). In studies using HCV antibody seroconversion, the window period between the last negative and the first positive antibody test varied widely across studies (4 weeks to 4 years). Considerable diversity was also observed with respect to the ALT threshold used to characterize ALT elevations, ranging from 2 to 20 times the upper limit of normal. HCV antibody seroconversion was used as a single criterion in 41% of the studies, while all other studies used at least two criteria (range: 2-9). Epidemiology/surveillance studies mostly used a more sensitive case definition, whereas treatment studies, natural history studies, and diagnosis studies used more specific case definitions.

CONCLUSIONS

Marked heterogeneity in case definitions for recent HCV infection was observed. Although a single case definition for recent HCV is not warranted, a degree of standardization within specific study categories would enable improved cross-study comparison and more uniform evaluation of HCV prevention and management strategies.

Female sex and IL28B, a synergism for spontaneous viral clearance in hepatitis C virus (HCV) seroconverters from a community-based cohort

BACKGROUND & AIMS

Since acute hepatitis C virus (HCV) infection is often asymptomatic, it is difficult to examine the rate and determinants of spontaneous clearance. Consequently, these studies are subject to bias, which can potentially lead to biased rates of viral clearance and risk estimates. We evaluated determinants of spontaneous HCV clearance among HCV seroconverters identified in a unique community-based cohort.

METHODS

Subjects were 106 drug users with documented dates of HCV seroconversion from the Amsterdam Cohort Study. Logistic regression was used to examine sociodemographic, behavioral, clinical, viral and host determinants, measured around acute infection, of HCV clearance.

RESULTS

The spontaneous viral clearance rate was 33.0% (95% confidence interval (CI) 24.2-42.8). In univariate analyses female sex and fever were significantly associated with spontaneous clearance. The favorable genotypes for rs12979860 (CC) and rs8099917 (TT) were associated with spontaneous clearance, although borderline significant. In multivariate analysis, females with the favorable genotype for rs12979860 (CC) had an increased odds to spontaneously clear HCV infection (adjusted OR 6.62, 95% 2.69-26.13), whereas females with the unfavorable genotype were as likely as men with the favorable and unfavorable genotype to clear HCV. Chronic Hepatitis B infection and absence of HIV coinfection around HCV seroconversion also favor HCV clearance.

CONCLUSIONS

This study shows that co-infection with HIV and HBV and genetic variation in the IL28B region play an important role in spontaneous clearance of HCV. Our findings suggest a possible synergistic interaction between female sex and IL28B in spontaneous clearance of HCV.

Early IL-10 predominant responses are associated with progression to chronic hepatitis C virus infection in injecting drug users

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.

The natural history of early hepatitis C virus evolution; lessons from a global outbreak in human immunodeficiency virus-1-infected individuals

New insights into the early viral evolution and cellular immune response during acute hepatitis C virus (HCV) infection are being gained following a global outbreak in human immunodeficiency virus-1 (HIV)-positive men who have sex with men. Cross-sectional and longitudinal sequence analysis at both the population and individual level have facilitated tracking of the HCV epidemic across the world and enabled the development of tests of viral diversity in individual patients in order to predict spontaneous clearance of HCV and response to treatment. Immunological studies in HIV-positive cohorts have highlighted the role of the CD4⁺ T-cell response in the control of early HCV infection and will increase the opportunity for the identification of protective epitopes that could be used in future vaccine development.

T-cell responses at baseline and during therapy with peginterferon-alpha and ribavirin are not associated with outcome in chronic hepatitis C infected patients

BACKGROUND

Since the association between hepatitis C virus (HCV)-specific T-cell responses both pre-treatment and during interferon-alpha based therapy and viral clearance is unresolved, a combined analysis of distinctive T-cell characteristics (proliferation and interferon-gamma production) is important to clarify this issue.

METHODS

Peripheral blood mononuclear cells (PBMC) collected in 22 chronic HCV infected patients at pre-treatment and at week 4 during pegIFN-alpha/ribavirin therapy, were stimulated with overlapping peptide pools in a [3H]-thymidine assay, an interferon-gamma-ELISA, and a sensitive 12-day T-cell expansion assay.

RESULTS

Compared to the [3H]-thymidine proliferation and interferon-gamma secretion assays, the 12-day T-cell expansion assay was more sensitive in detecting T-cell responses. No significant association was demonstrated between pre-treatment HCV-specific CD4+ or CD8+ T-cell responses and either a sustained virological response (SVR) or a rapid virological response (RVR). However, a skewing of individual responses towards the non-structural antigens was observed. During pegIFN-alpha/ribavirin therapy, HCV-specific CD4+ and CD8+ T-cells declined similarly in both SVR/RVR and non-SVR/non-RVR patients.

CONCLUSION

No correlation was found between the magnitude of pre-treatment HCV-specific T-cell responses and the outcome of pegIFN-alpha/ribavirin therapy in terms of SVR and RVR. Moreover, the magnitude of HCV-specific T-cell responses declined in all patients early during treatment.

Virological footprint of CD4+ T-cell responses during chronic hepatitis C virus infection

Human and animal model evidence suggests that CD4⁺ T cells play a critical role in the control of chronic hepatitis C virus (HCV) infection. However, despite their importance, the mechanism behind the failure of such populations in chronic disease is not understood and the contribution of viral mutation is not known. To address this, this study defined the specificity and virological footprint of CD4⁺ T cells in chronic infection. CD8⁺ T-cell-depleted peripheral blood mononuclear cells from 61 HCV genotype 1-infected patients were analysed against a panel of peptides covering the HCV genotype 1 core – a region where CD4⁺ T-cell responses may be reproducibly obtained. In parallel, the core region and E2 protein were sequenced. Gamma interferon-secreting CD4⁺ T-cell responses directed against multiple epitopes were detected in 53 % of individuals, targeting between one and four peptides in the HCV core. Viral sequence evaluation revealed that these CD4⁺ T-cell responses were associated with mutants in 2/21 individuals. In these two cases, the circulating sequence variant was poorly recognized by host CD4⁺ T cells. Bioinformatics analyses revealed no overall evidence of selection in the target epitopes and no differences between the groups with and without detectable CD4⁺ T-cell responses. It was concluded that sustained core peptide-specific CD4⁺ T-cell responses may be reproducibly measured during chronic HCV infection and that immune escape may occur in specific instances. However, overall the virological impact of such responses is limited and other causes for CD4⁺ T-cell failure in HCV must be sought.

Comprehensive longitudinal analysis of hepatitis C virus (HCV)-specific T cell responses during acute HCV infection in the presence of existing HIV-1 infection

The aim of this study was to study the development of HCV-specific T cell immunity during acute HCV infection in the presence of an existing HIV-1 infection in four HIV-1 infected men having sex with men. A comprehensive analysis of HCV-specific T cell responses was performed at two time points during acute HCV infection using a T cell expansion assay with overlapping peptide pools spanning the entire HCV genome Three patients with (near) normal CD4+ T cell counts (range 400-970 x 10(6)/L) either resolved (n=1) or temporary suppressed HCV RNA. In contrast, one patient with low CD4+ T cell counts (330 x 10(6)/L), had sustained high HCV RNA levels. All four patients had low HCV-specific CD8+ T cell responses, and similar magnitudes of CD4+ T cell responses. Interestingly, individuals with resolved infection or temporary suppression of HCV-RNA had HCV-specific CD4+ T cell responses predominantly against nonstructural (NS) proteins. While the individual with high HCV RNA plasma concentrations had CD4+ T cell responses predominantly directed against Core. Our data show that an acute HCV infection in an HIV-1 infected person can be suppressed in the presence of HCV-specific CD4+ T cell response targeting non-structural proteins. However further research is needed in a larger group of patients to evaluate the role of HIV-1 on HCV-specific T cell responses in relation to outcome of acute HCV infection.

Hepatitis infection in the treatment of opioid dependence and abuse

Many new and existing cases of viral hepatitis infections are related to injection drug use. Transmission of these infections can result directly from the use of injection equipment that is contaminated with blood containing the hepatitis B or C virus or through sexual contact with an infected individual. In the latter case, drug use can indirectly contribute to hepatitis transmission through the dis-inhibited at-risk behavior, that is, unprotected sex with an infected partner. Individuals who inject drugs are at-risk for infection from different hepatitis viruses, hepatitis A, B, or C. Those with chronic hepatitis B virus infection also face additional risk should they become co-infected with hepatitis D virus. Protection from the transmission of hepatitis viruses A and B is best achieved by vaccination. For those with a history of or who currently inject drugs, the medical management of viral hepatitis infection comprising screening, testing, counseling and providing care and treatment is evolving. Components of the medical management of hepatitis infection, for persons considering, initiating, or receiving pharmacologic therapy for opioid addiction include: testing for hepatitis B and C infections; education and counseling regarding at-risk behavior and hepatitis transmission, acute and chronic hepatitis infection, liver disease and its care and treatment; vaccination against hepatitis A and B infection; and integrative primary care as part of the comprehensive treatment approach for recovery from opioid abuse and dependence. In addition, participation in a peer support group as part of integrated medical care enhances treatment outcomes. Liver disease is highly prevalent in patient populations seeking recovery from opioid addiction or who are currently receiving pharmacotherapy for opioid addiction. Pharmacotherapy for opioid addiction is not a contraindication to evaluation, care, or treatment of liver disease due to hepatitis virus infection. Successful pharmacotherapy for opioid addiction stabilizes patients and improves patient compliance to care and treatment regimens as well as promotes good patient outcomes. Implementation and integration of effective hepatitis prevention programs, care programs, and treatment regimens in concert with the pharmacological therapy of opioid addiction can reduce the public health burdens of hepatitis and injection drug use.