Direct-Acting Antivirals Cure Innate Immunity in Chronic Hepatitis C

Reconstitution of T follicular helper-humoral immune axis with elimination of hepatitis C virus

Exhaustion of Hepatitis C Virus (HCV)-specific T cells and abnormal B cell function is a hallmark of chronic HCV infection. Direct-acting antiviral (DAA) therapies are effective in achieving sustained virologic response (SVR), however, whether successful DAA treatment reconstitute T follicular helper (T_FH)-B cell axis in HCV patients is unclear. Here, we aimed to evaluate the immunological changes in global and HCV-specific CD4 + CXCR5 + T_FH, CD4 + CXCR5-T and B cells in 20 HCV patients who achieved SVR with Sofosbuvir and Ledipasvir for 12 weeks and compared with 15 healthy controls (HC). Global and HCV-specific CD4 + CXCR5 + T_FH, CD4 + CXCR5-T and CD19 + B cells had significant phenotypic and functional reconstitution post DAA therapy. Reconstitution of effector, central and terminally differentiated memory cell population and increased ICOS and BCL6 expression was seen in HCV patients at SVR12. HCV-specific cytokines were also improved post DAA. Exhausted and regulatory B cells were declined whereas memory B cells were expanded post DAA therapy. Importantly, frequencies of T_FH cells were significantly associated with HCV RNA reduction, expansion of memory B and plasmablasts, while negatively associated with exhausted/regulatory B cells. Our results demonstrate that SVR with DAA therapy is effective in the reconstitution of phenotypic and functional abnormalities of T_FH-B cell axis.

Control of HCV Infection by Natural Killer Cells and Macrophages

Host defense against invading pathogens within the liver is dominated by innate immunity. Natural killer (NK) cells have been implicated at all stages of hepatitis C virus (HCV) infection, from providing innate protection to contributing to treatment-induced clearance. Decreased NK cell levels, altered NK cell subset distribution, activation marker expression, and functional polarization toward a cytolytic phenotype are hallmarks of chronic HCV infection. Interferon α (IFN-α) is a potent activator of NK cells; therefore, it is not surprising that NK cell activation has been identified as a key factor associated with sustained virological response (SVR) to IFN-α-based therapies. Understanding the role of NK cells, macrophages, and other innate immune cells post-SVR remains paramount for prevention of disease pathogenesis and progression. Novel strategies to treat liver disease may be aimed at targeting these cells.

Nivolumab-Induced Autoimmune-Like Cholestatic Hepatitis in a Liver Transplant Recipient

Cancer treatment has taken giant strides in recent years with the advent of immunotherapy, including checkpoint inhibitors. The use of these medications in liver transplant recipients has been debated, and the added effect of previous hepatitis C infection on the immune system in this setting, is poorly understood. We present a case of cholestatic hepatitis after the treatment of recurrent hepatocellular carcinoma with nivolumab in the post-transplant period. Understanding the pathophysiology is relevant to improving the management of this type of liver injury and expanding our knowledge of programmed death-1 inhibitors in liver transplant recipients.

Hepatitis C Virus (HCV) Clearance After Treatment With Direct-Acting Antivirals in Human Immunodeficiency Virus (HIV)-HCV Coinfection Modulates Systemic Immune Activation and HIV Transcription on Antiretroviral Therapy

Background

Hepatitis C virus (HCV) coinfection among people with human immunodeficiency virus (HIV) might perturb immune function and HIV persistence. We aimed to evaluate the impact of HCV clearance with direct-acting antivirals (DAAs) on immune activation and HIV persistence in HIV/HCV-coinfected individuals on antiretroviral therapy (ART).

Methods

In a prospective observational study, ART-treated participants with HIV/HCV coinfection received sofosbuvir/daclatasvir ± ribavirin (n = 19). Blood samples were collected before DAA therapy, at the end of treatment, and 12 months after DAA termination (12MPT). T- and natural killer (NK)-cell phenotype, soluble plasma factors, cell-associated (CA)-HIV deoxyribonucleic acid (DNA) forms (total, integrated, 2LTR), CA-unspliced (US) and multiple-spliced ribonucleic acid (RNA), and plasma HIV RNA were evaluated.

Results

Hepatitis C virus clearance was associated with (1) a downmodulation of activation and exhaustion markers in CD4⁺, CD8⁺ T, and NK cells together with (2) decreased plasma levels of Interferon gamma-induced protein 10 (IP10), interleukin-8 (IL-8), soluble (s)CD163 and soluble intercellular adhesion molecule (sICAM). Cell-associated US HIV RNA was significantly higher at 12MPT compared to baseline, with no change in HIV DNA or plasma RNA.

Conclusions

Elimination of HCV in HIV/HCV-coinfected individuals alters immune function and the transcriptional activity of latently infected cells. This report provides insights into the effects of HCV coinfection in HIV persistence and regards coinfected subjects as a population in which HIV remission might prove to be more challenging.

Hepatitis B virus in patients with chronic hepatitis C treated with direct antiviral agents

INTRODUCTION

cases of hepatitis B virus (HBV) reactivation have been reported in patients with hepatitis C virus (HCV) treated with direct antiviral agents (DAA).

OBJECTIVES AND METHODS

the main objectives of the present study are: a) to determine the prevalence of HBV/HCV coinfection in HCV patients treated with DAAs in the Autonomous Community of Madrid (CM) and also to determine the incidence and clinical relevance of HBV reactivation; and b) to determine the HBV screening rates in HCV patients in our region. For that purpose, 1,337 HCV patients were consecutively treated with DAAs in two hospitals located in South CM between January 2015 and June 2017.

RESULTS

nine of the 1,337 (0.67%) participants were HBsAg positive and 356 (26.6%) had previous HBV infection markers. Two of the four (50%) HBsAg positive patients with untreated HBV developed a virological reactivation, but not a biochemical reaction. Of the 356 patients with previous HBV infection markers, all had normal transaminases at the end of treatment and during follow-up. The HBV screening rate amounted to 92.9% of the cohort.

CONCLUSIONS

the prevalence of HBV (HBsAg positive) infection in patients with chronic hepatitis C in the southern area of the CM is low. HBV reactivation in HBsAg positive patients treated with DAAs is common, although without clinical relevance. In our region, there is a high rate of HBV screening in patients with HCV that are likely treated with DAAs.

Modeling indicates efficient vaccine-based interventions for the elimination of hepatitis C virus among persons who inject drugs in metropolitan Chicago

BACKGROUND AND AIMS

Persons who inject drugs (PWID) are at highest risk for acquiring and transmitting hepatitis C (HCV) infection. The recent availability of oral direct-acting antiviral (DAA) therapy with reported cure rates >90% can prevent HCV transmission, making HCV elimination an attainable goal among PWID. The World Health Organization (WHO) recently proposed a 90% reduction in HCV incidence as a key objective. However, given barriers to the use of DAAs in PWID, including cost, restricted access to DAAs, and risk of reinfection, combination strategies including the availability of effective vaccines are needed to eradicate HCV as a public health threat. This study aims to model the cost and efficacy of a dual modality approach using HCV vaccines combined with DAAs to reduce HCV incidence by 90% and prevalence by 50% in PWID populations.

METHODS

We developed a mathematical model that represents the HCV epidemic among PWID and calibrated it to empirical data from metropolitan Chicago, Illinois. Four medical interventions were considered: vaccination of HCV naive PWID, DAA treatment, DAA treatment followed by vaccination, and, a combination of vaccination and DAA treatment.

RESULTS

The combination of vaccination and DAAs is the lowest cost-expensive intervention for achieving the WHO target of 90% incidence reduction. The use of DAAs without a vaccine is much less cost-effective with the additional risk of reinfection after treatment. Vaccination of naïve PWID alone, even when scaled-up to all reachable PWID, cannot achieve 90% reduction of incidence in high-prevalence populations due to infections occurring before vaccination. Similarly, the lowest cost-expensive way to halve prevalence in 15 years is through the combination of vaccination and DAAs.

CONCLUSIONS

The modeling results underscore the importance of developing an effective HCV vaccine and augmenting DAAs with vaccines in HCV intervention strategies in order to achieve efficient reductions in incidence and prevalence.

Molecular Mechanisms Involved in HCC Recurrence after Direct-Acting Antiviral Therapy

Chronic hepatitis C is associated with a high risk of developing hepatocellular carcinoma (HCC) because of a direct effect of the Hepatitis C Virus (HCV) proteins and an indirect oncogenic effect of chronic inflammation and impaired immune response. The treatment of chronic hepatitis C markedly reduces all-cause mortality; in fact, interferon-based treatment has shown a reduction of HCC incidence of more than 70%. The recent introduction of the highly effective direct-acting antivirals (DAAs) has completely changed the scenario of chronic hepatitis C (CHC) with rates of HCV cure over 90%. However, an unexpectedly high incidence of HCC recurrence was observed in patients after DAA treatment (27% versus 0.4–2% in patients who received interferon treatment). The mechanism that underlies the high rate of tumor relapse is currently unknown and is one of the main issues in hepatology. We reviewed the possible mechanisms involved in HCC recurrence after DAA treatment.

Modulation of the Immune System in Chronic Hepatitis C and During Antiviral Interferon-Free Therapy

The treatment of patients with chronic hepatitis C virus (HCV) infection has changed tremendously over the past 2 years, with an increasing variety of all-oral direct-acting antiviral (DAA) treatment regimens available for different HCV genotypes and distinct clinical settings. These treatments have significantly improved safety in patients with advanced liver disease compared with interferon (IFN)-based regimens. HCV modifies the human immune system to escape immunosurveillance via several mechanisms. One of the basic mechanisms of HCV is the ability to “switch” the immune response by reducing the activity of cells responsible for the elimination of virus-infected cells. IFN-free DAA treatment regimens provide a unique opportunity to assess the effect of HCV elimination on the immune system. Abrupt changes in the immune system can in some cases be responsible for two alarming processes: viral reactivation in patients with chronic hepatitis B and recurrence of hepatocellular carcinoma in patients with previous successful cancer treatment.

Early and late changes in natural killer cells in response to ledipasvir/sofosbuvir treatment

Chronic hepatitis C virus (HCV) infection is characterized by dysregulated natural killer (NK) cell responses. NKs play a critical role in achieving sustained responses to interferon (IFN)‐α‐based therapy. Rapid sustained HCV‐RNA clearance is now achieved with direct‐acting antivirals (DAAs). Studies of patients receiving first‐wave DAAs suggest NK functional restoration. Here, we investigate the effect of mainstream DAA treatment on NKs. We collected a prospective cohort of male HCV genotype 1‐infected patients treated with ledipasvir/sofosbuvir (n = 22). Peripheral blood was obtained at treatment start, week 2 (W2), W4, W8, and W12 of treatment and 12 weeks posttreatment. Flow cytometry was used to characterize NK responses to therapy. Mean baseline viral load was 1.75 million IU/mL. All subjects rapidly cleared virus and remained HCV RNA‐negative posttreatment. No change was seen in total NK levels; however, the frequency of immature NKs (clusters of differentiation [CD]56^bright) decreased by W2 and was maintained throughout the study. Phenotypic changes were evident by W2/W4, coincident with rapid viral clearance. At W2, T‐cell immunoglobulin and mucin‐domain containing‐3 and CD161 were significantly increased, returning to pretreatment levels by W12. Some changes were not evident until late (W12 or posttreatment). Down‐regulation of several activation markers, including NKp30 and tumor necrosis factor–related apoptosis‐inducing ligand, was observed at W12 and sustained posttreatment. No difference was observed in IFN‐γ production or cytokine‐mediated killing of NK‐sensitive cell line K562 posttreatment compared to pretreatment. Conclusion: Our phenotype data suggest transient activation followed by dampening of NK cell activity to pretreatment levels. The NK response to ledipasvir/sofosbuvir is not universal in a homogeneous patient cohort. More studies are needed to elucidate the roles of NK cells in IFN‐free regimens, which will have implications for protection from re‐infection and fibrosis progression. (Hepatology Communications 2018;2:364‐375)

Is weak CD4+ gain in the course of suppressive combination antiretroviral therapy for HIV infection a current clinical challenge? A case report and brief review of the literature

Background

Individuals lacking immune recovery during suppressive cART will still represent a clinical issue in the years to come, given the high proportion of HIV-infected subjects introducing therapy late in the course of disease. Understanding the mechanisms underlying poor CD4+ T-cell gain is crucial for the correct clinical management of individuals in this context.

Case presentation

An HIV-infected subject with poor CD4+ T-cell gain in the course of suppressive antiretroviral therapy was extensively investigated to identify the mechanisms behind inadequate CD4+ reconstitution. In particular, we studied the phenotype of circulating T-cells, interleukin-7 signaling in peripheral blood and bone marrow, gut function and microbial translocation markers as well as the composition of the faecal microbiota. Numerous therapeutic interventions ranging from antiretroviral therapy intensification to immunotherapy and anti-hepatitis C virus treatment were also employed in order to target the possible causes of poor immune-recovery.

Conclusions

Poor CD4+ T-cell gain on suppressive antiretroviral therapy is multifactorial and thus represents a clinical challenge. Clinicians should investigate subjects’ immune profile as well as possible causes of chronic antigenic stimulation for the administration of the most appropriate therapeutic strategies in this setting.

Monocytes inhibit hepatitis C virus-induced TRAIL expression on CD56bright NK cells

BACKGROUND & AIMS

Natural killer (NK) cells play an important role in the pathogenesis of hepatitis C virus (HCV) infection. We have previously shown that culture-derived HCV (HCVcc) enhance tumor necrosis-factor-related apoptosis-inducing ligand (TRAIL) expression on healthy NK cells, but not on those from patients infected with HCV, which was likely dependent on accessory cells. Here we sought to elucidate the mechanisms involved in altered TRAIL upregulation in this setting.

METHODS

Peripheral blood mononuclear cells (PBMC) from controls and patients infected with HCV were exposed to HCVcc. Cell depletions were performed to identify cells responsible for NK cell activation. Flow cytometry and ELISA were used to identify the cytokines involved in the NK activation process.

RESULTS

In patients infected with HCV, soluble factors secreted by control PBMC restored the ability of NK cells to express TRAIL. Of note, CD14+ cell depletion had identical effects upon virus exposure and promoted increased degranulation. Moreover, increased concentrations of interleukin (IL)-18 binding protein a (IL-18BPa) and IL-36 receptor antagonist (IL-36RA) were observed after PBMC exposure to HCVcc in patients with HCV. HCVcc-induced NK cell TRAIL expression was inhibited by IL-18BPa and IL-36RA in control subjects. There were statistically significant correlations between IL-18BPa and indices of liver inflammation and fibrosis, supporting a role for this protein in the pathogenesis of chronic HCV infection.

CONCLUSIONS

During chronic HCV infection, monocytes play a key role in negative regulation of NK cell activation, predominantly via secretion of inhibitors of IL-18 and IL-36.

LAY SUMMARY

Coordination and collaboration between immune cells are essential to fight pathogens. Herein we show that during HCV infection monocytes secrete IL-18 and IL-36 inhibitory proteins, reducing NK cell activation, and consequently inhibiting their ability to express TRAIL and kill target cells.

Current progress in host innate and adaptive immunity against hepatitis C virus infection

Hepatitis C virus (HCV) infects more than 170 million people worldwide and is the main cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Although the newly developed direct-acting antivirals (DAAs) have transformed the treatment of HCV infection, controlling HCV infection on a global scale remains a challenge because of the high cost, low resistance barrier of DAAs and lack of HCV vaccine. The host immune responses associated with HCV infection, especially HCV-specific T cellular immunity, determine the outcome of HCV infection: either acute or chronic infection. It is important to fully interpret the immunopathogenesis of HCV infection and consequently to exploit effective strategies to eliminate HCV. Here, we review the current progress in HCV immunology, which will deepen our understanding of the spectrum of HCV infection and immunity in humans.

Hepatitis C virus-induced NK cell activation causes metzincin-mediated CD16 cleavage and impaired antibody-dependent cytotoxicity

BACKGROUND & AIMS

The Fc receptor family for immunoglobulin (Ig)G type III (FcγRIII, CD16) is an activating receptor on natural killer (NK) cells and an essential mediator of antibody-dependent cellular cytotoxicity (ADCC). There is only limited information on its role during chronic hepatitis C virus (HCV) infection. We studied CD16 expression in relation to NK cell functional activity in HCV-infected patients and sought mechanistic insights into virus-induced modulation.

METHODS

NK cell CD16 expression and activation status were evaluated ex vivo by flow cytometry in HCV-infected patients and healthy controls (HC) as well as in vitro after co-culture with HCV-infected HuH7.5 cells. Rituximab-mediated ADCC was assessed in HC and HCV-infected patients using Daudi cells as a target. The role of metzincins in CD16 down-modulation was assessed using specific inhibitory molecules and by evaluating intracellular mRNA levels.

RESULTS

HCV-infected patients exhibited increased frequencies of ex vivo activated NK cells and a concomitantly decreased NK CD16 expression, which resulted in impaired ADCC activity. Moreover, exposure of NK cells to culture-derived HCV recapitulated the ex vivo findings of decreased CD16 expression and increased NK cell activation. Importantly, blockade of metzincin-mediated shedding activity, including selective a disintegrin and metalloproteinase 17 (ADAM-17) inhibition, restored NK CD16 expression. Successful treatment with direct-acting antivirals partially improved NK ADCC function despite delayed CD16 reconstitution.

CONCLUSION

Chronic HCV infection induces NK cell activation resulting in ADAM-17-dependent CD16 shedding and consequent impaired ADCC function. Altered ADCC may contribute to failure to eradicate HCV-infected hepatocytes.

LAY SUMMARY

We show here that hepatitis C virus (HCV) activates natural killer (NK) lymphocytes which, as a consequence, loose their Fc receptor for IgG (CD16), an essential molecule for antibody binding. We show that this occurs through the action of enzymes named metzincins, resulting in altered NK-mediated antibody-dependent killing (ADCC) of target cells. This mechanism may contribute to HCV persistence and may represent a general phenomenon whereby some viruses can escape host's immune responses.

Herpes virus reactivation after initiation of interferon-free antiviral agents in HIV-HCV-coinfected subjects: a new immune restoration disease?

We report four HCV-HIV-coinfected patients who developed herpes zoster or muco-cutaneous herpes virus disease shortly after starting interferon-free antiviral treatment for HCV. We suggest that in our patients the prompt clearance of HCV following direct-acting antivirals leads to a paradoxical effect on the innate and adaptive immune system mediating the reactivation of herpetic infection.

Twelve-week ribavirin-free direct-acting antivirals for treatment-experienced Chinese with HCV genotype 1b infection including cirrhotic patients

BACKGROUND

Treatment-experienced chronic hepatitis C (CHC) genotype (GT) 1b represents a major medical burden in China. We evaluate the efficacy, safety and cost-effectiveness of ribavirin (RBV)-free pan-oral direct-acting antivirals (DAAs) in treatment-experienced Chinese with GT1b CHC, including patients with cirrhosis.

METHODS

One hundred forty treatment-experienced GT1b CHC Chinese with and without cirrhosis were included in this study. Ninety-four patients were treated with either daclatasvir (DCV, 60 mg)-sofosbuvir (SOF, 400 mg) (group 1, n = 46) or ledipasvir (LDV, 90 mg)-SOF (400 mg) (group 2, n = 48) for 12 weeks. Forty-six patients treated with pegylated interferon and RBV therapy for 72 weeks were enrolled as the control group (group 3). Patients were followed at 4-weekly intervals till 24 weeks after the end of treatment.

RESULTS

All patients in group 1 (46/46, 100 %) and 2 (48/48, 100 %) had achieved sustained virologic response at 24 weeks after the end of treatment (SVR 24), which was significantly higher than that of group 3 (13/46, 28.3 %) (p < 0.001). The SVR 24 rates of cirrhotic patients in group 1 (27/27, 100 %) and 2 (27/27, 100 %) were also significantly higher than that of group 3 (3/25, 12 %) (p < 0.001). Twelve weeks of RBV-free LDV-SOF and DCV-SOF was either cost-saving or cost-effective. Adverse events were significantly lower in group 1 and 2 compared with group 3 (p < 0.001).

CONCLUSION

Compared with standard therapies, 12 weeks of RBV-free DAA therapies is highly effective, well tolerated and cost-effective in treatment-experienced Chinese with GT1b CHC including patients with cirrhosis.

Memory re-differentiation and reduced lymphocyte activation in chronic HCV-infected patients receiving direct-acting antivirals

Recently, the treatment of HCV has advanced significantly due to the introduction of direct-acting antivirals (DAAs). Studies using interferon (IFN)-containing regimens failed to consistently show restoration of immunologic responses. Therefore, IFN-free DAA formulations provide a unique opportunity to dissect the immunologic effect of HCV cure. This study investigates the restoration of the immune compartment as a consequence of rapid viral clearance in patients successfully treated with DAAs and in the absence of IFN and ribavirin. Here, we evaluate the immunologic changes that occurred following DAA-mediated HCV cure. Peripheral blood from nineteen previously treatment-naïve patients with chronic HCV genotype 1a/1b who received an IFN and ribavirin-free regimen of daclatasvir, asunaprevir and BMS-791325 was evaluated. Immune reconstitution occurs in patients in whom HCV was successfully eradicated via DAA therapy. Restoration of the CD4(+) T-cell compartment in the peripheral blood and a re-differentiation of the T lymphocyte memory compartment resulted in a more effector memory cell population and a reduction in expression in the co-inhibitory molecule TIGIT in bulk T lymphocytes. Furthermore, we observed a partial reversal of the exhausted phenotype in HCV-specific CD8(+) T cells and a dampening of the activation state in peripheral NK cells. Collectively, our data provide the groundwork for dissecting the effect of DAA therapy on the immune system and identifying novel mechanisms by which chronic HCV infection exerts immunosuppressive effects on T cells through the recently described co-inhibitory molecule TIGIT.