Effects of HCV on basal and tat-induced HIV LTR activation

HIV-reservoir size is not affected either by HCV coinfection or by direct acting antivirals (DAAs) therapy

The role of HCV on the HIV reservoir is controversial since the reduction on HIV-DNA levels after HCV eradication with IFNα/RBV treatment seems to be the result of drugs instead of HCV clearance. We assessed whether HCV eradication can decrease HIV-DNA content in HIV/HCV-coinfected patients treated with direct-acting antivirals, DAAs (IFNα/RBV-free regimens). Cell-associated HIV-DNA was measured by ddPCR in 25 HIV-monoinfected and 25 HIV/HCV-coinfected patients. There were no differences in HIV-DNA levels between groups neither at baseline nor at 12 weeks after DAAs treatment completion. Our results indicate that HCV does not appear to influence the HIV reservoir size and suggest the lack of an anti-HIV action for DAAs.

A Tale of Two Viruses: Immunological Insights Into HCV/HIV Coinfection

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.

The Regulation of Prototype Foamy Virus 5'Long Terminal Repeats and Internal Promoter by Endogenous Transcription Factors

BACKGROUND

For foamy virus, the transactivator of spumaretrovirus (Tas) could bind directly to target DNA sequences termed as Tas responsive elements and trigger the viral internal promoter (IP) and long terminal repeat (LTR) promoters. The cellular endogenous factors also play an important role in viral gene expressions. We hypothesized that except the viral transcription factor Tas, the cellular endogenous factors also affect the viral gene expression.

METHODS

The full length of the prototype foamy virus (PFV) genome (U21247) was used to predict the potential binding sites of the transcription factors by online software JASPAR (http://jaspar.genereg.net) and Softberry (http://linux1.softberry.com/berry.phtml?topic=index&group=programs&subgroup=promoter). The Dual-Luciferase® Reporter Assay System (Promega, USA) was used to confirm the relative luciferase activities of the test groups. The different representative activating agents or inhibitors of each canonical signal pathway were used to identify the impact of these pathways on PFV 5'LTR and IP promoters.

RESULTS

The results showed different cellular endogenous factors might have respective effects on PFV 5'LTR and IP. It is worth mentioning that activator protein-1 and BCL2-associated athanogene 3, 2 kinds of vital proteins associated with NF-κB and PKC pathways, could activate the basal activity of 5'LTR and IP promoters but inhibit the Tas-regulated activity of both promoters. Furthermore, PFV Tas was identified to trigger the transcription of the NF-κB promoter.

CONCLUSION

NF-κB had a negative effect on PFV 5'LTR and IP promoter activities, the PKC pathway might upregulate 5'LTR and IP promoter activities, and the JNK and NF-AT signal pathway could increase the Tas-regulated promoter activity of PFV 5'LTR. This study sheds light on the interaction between PFV and the host cell and may help utilize the viral promoters in retroviral vectors designed for gene transfer experiments.

Current and future challenges in HCV: insights from an Italian experts panel

BACKGROUND

The recent availability of direct acting antiviral drugs (DAAs) has drastically changed hepatitis C virus (HCV) treatment scenarios, due to the exceedingly high rates of sustained virological response (SVR) and excellent tolerability allowing for treatment at all disease stages.

METHODS

A panel of Italian experts was convened twice, in November 2016 and January 2017, to provide further support on some open issues and provide guidance for personalized HCV care, also in light of forthcoming regimens.

RESULTS AND CONCLUSIONS

Treatment recommendations issued by international and national liver societies to guide clinicians in the management of HCV infection are constantly updated due to accumulating new data. Such recommendations may not be applicable to all healthcare settings for a variety of reasons. Moreover, some gaps still remain and the spectrum of patients to be treated is also evolving.

Immunogenetic studies of the hepatitis C virus infection in an era of pan-genotype antiviral therapies - Effective treatment is coming

What are the factors that influence human hepatitis C virus (HCV) infection, hepatitis status establishment, and disease progression? Firstly, one has to consider the genetic background of the host and HCV genotypes. The immunogenetic host profile will reflect how each infected individual deals with infection. Secondly, there are environmental factors that drive susceptibility or resistance to certain viral strains. These will dictate (I) the susceptibility to infection; (II) whether or not an infected person will promote viral clearance; (III) the immune response and the response profile to therapy; and (IV) whether and how long it would take to the development of HCV-associated diseases, as well as their severity. Looking at this scenario, this review addresses clinical aspects of HCV infection, following by an update of molecular and cellular features of the immune response against the virus. The evasion mechanisms used by HCV are presented, considering the potential role of exosomes in infection. Genetic factors influencing HCV infection and pathogenesis are the main topics of the article. Shortly, HLAs, MBLs, TLRs, ILs, and IFNLs genes have relevant roles in the susceptibility to HCV infection. In addition, ILs, IFNLs, as well as TLRs genes are important modulators of HCV-associated diseases. The viral aspects that influence HCV infection are presented, followed by a discussion about evolutionary aspects of host and HCV interaction. HCV and HIV infections are close related. Thus, we also present a discussion about HIV/HCV co-infection, focusing on cellular and molecular aspects of this interaction. Pharmacogenetics and treatment of HCV infection are the last topics of this review. The understanding of how the host genetics interacts with viral and environmental factors is crucial for the development of new strategies to prevent HCV infection, even in an era of potential development of pan-genotypic antivirals.

HCV coinfection contributes to HIV pathogenesis by increasing immune exhaustion in CD8 T-cells

Background

There are several contributors to HIV-pathogenesis or insufficient control of the infection. However, whether HIV/HCV-coinfected population exhibits worst evolution of HIV-pathogenesis remains unclear. Recently, some markers of immune exhaustion have been proposed as preferentially upregulated on T-cells during HIV-infection. Herein, we have analyzed T-cell exhaustion together with several other contributors to HIV-pathogenesis that could be affected by HCV-coinfection.

Patients and methods

Ninety-six patients with chronic HIV-infection (60 HIV-monoinfected and 36 HIV/HCV-coinfected), and 20 healthy controls were included in the study. All patients were untreated for both infections. Several CD4 and CD8 T-cell subsets involved in HIV-pathogenesis were investigated. Non-parametric tests were used to establish differences between groups and associations between variables. Multivariate linear regression was used to ascertain the variables independently associated with CD4 counts.

Results

HIV-patients presented significant differences compared to healthy controls in most of the parameters analyzed. Both HIV and HIV/HCV groups were comparable in terms of age, CD4 counts and HIV-viremia. Compared to HIV group, HIV/HCV group presented significantly higher levels of exhaustion (Tim3⁺PD1^- subset) in total CD8⁺ T-cells (p = 0.003), and higher levels of exhaustion in CD8⁺HLADR⁺CD38⁺ (p = 0.04), CD8⁺HLADR^-CD38⁺ (p = 0.009) and CD8⁺HLADR^-CD38^- (p = 0.006) subsets of CD8⁺ T-cells. Interestingly these differences were maintained after adjusting by CD4 counts and HIV-viremia.

Conclusions

We show a significant impact of HCV-coinfection on CD8 T-cells exhaustion, an important parameter associated with CD8 T-cell dysfunction in the setting of chronic HIV-infection. The relevance of this phenomenon on immunological and/or clinical HIV progression prompts HCV treatment to improve management of coinfected patients.

MECHANISMS OF INTERACTION OF VIRAL CAUSATIVE AGENTS IN PATIENTS CO-INFECTED WITH HUMAN IMMUNODEFICIENCY AND HEPATITIS C VIRUSES

In patients infected with human immunodeficiency virus (HIV) in 20 - 30% of cases co-infection with hepatitis C virus (HCV) is observed, that is associated with common routes of transmission for these causative agents. The main cause of lethal outcome for co-infected patients is liver damage. Thus, analysis of mechanisms of mutual influence of HIV and HCV under the conditions of co-infection gains special attention, that can be examined from both standpoints of direct inter-molecular interaction of 2 viral causative agents, as well as from the position of their immune-mediated effect. Negative effect of HIV on the course of fibrosis process in liver during HCVinfection is associated with the feature of this virus to cause deep alteration in the immune system by direct damage of CD4+ cells, disruption of mechanisms of immunological memory, suppression of functions of liver fraction of NK and NKT, as well as its ability of co-receptor interaction with hepatocytes and stellate cells, enhancing progress of fibrosis alterations and HCV replication in liver. HCV is also established to effect replication of HIV, stimulate infection of macrophages with this virus. All these events facilitate the rise in lethality during HIV and HCV co-infection.

Systematic review and meta-analysis of hepatitis C virus infection and HIV viral load: new insights into epidemiologic synergy

INTRODUCTION

Hepatitis C virus (HCV) and HIV infection frequently co-occur due to shared transmission routes. Co-infection is associated with higher HCV viral load (VL), but less is known about the effect of HCV infection on HIV VL and risk of onward transmission.

METHODS

We undertook a systematic review comparing 1) HIV VL among ART-naïve, HCV co-infected individuals versus HIV mono-infected individuals and 2) HIV VL among treated versus untreated HCV co-infected individuals. We performed a random-effects meta-analysis and quantified heterogeneity using the I(2) statistic. We followed Cochrane Collaboration guidelines in conducting our review and PRISMA guidelines in reporting results.

RESULTS AND DISCUSSION

We screened 3925 articles and identified 17 relevant publications. A meta-analysis found no evidence of increased HIV VL associated with HCV co-infection or between HIV VL and HCV treatment with pegylated interferon-alpha-2a/b and ribavirin.

CONCLUSIONS

This finding is in contrast to the substantial increases in HIV VL observed with several other systemic infections. It presents opportunities to elucidate the biological pathways that underpin epidemiological synergy in HIV co-infections and may enable prediction of which co-infections are most important to epidemic control.

Links between Human LINE-1 Retrotransposons and Hepatitis Virus-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) accounts for approximately 80% of liver cancers, the third most frequent cause of cancer mortality. The most prevalent risk factors for HCC are infections by hepatitis B or hepatitis C virus. Findings suggest that hepatitis virus-related HCC might be a cancer in which LINE-1 retrotransposon, often termed L1, activity plays a potential role. Firstly, hepatitis viruses can suppress host defense factors that also control L1 mobilization. Secondly, many recent studies also have indicated that hypomethylation of L1 affects the prognosis of HCC patients. Thirdly, endogenous L1 retrotransposition was demonstrated to activate oncogenic pathways in HCC. Fourthly, several L1 chimeric transcripts with host or viral genes are found in hepatitis virus-related HCC. Such lines of evidence suggest a linkage between L1 retrotransposons and hepatitis virus-related HCC. Here, I briefly summarize current understandings of the association between hepatitis virus-related HCC and L1. Then, I discuss potential mechanisms of how hepatitis viruses drive the development of HCC via L1 retrotransposons. An increased understanding of the contribution of L1 to hepatitis virus-related HCC may provide unique insights related to the development of novel therapeutics for this disease.

Virological Mechanisms in the Coinfection between HIV and HCV

Due to shared transmission routes, coinfection with Hepatitis C Virus (HCV) is common in patients infected by Human Immunodeficiency Virus (HIV). The immune-pathogenesis of liver disease in HIV/HCV coinfected patients is a multifactorial process. Several studies demonstrated that HIV worsens the course of HCV infection, increasing the risk of cirrhosis and hepatocellular carcinoma. Also, HCV might increase immunological defects due to HIV and risk of comorbidities. A specific cross-talk among HIV and HCV proteins in coinfected patients modulates the natural history, the immune responses, and the life cycle of both viruses. These effects are mediated by immune mechanisms and by a cross-talk between the two viruses which could interfere with host defense mechanisms. In this review, we focus on some virological/immunological mechanisms of the pathogenetic interactions between HIV and HCV in the human host.

Immuno-pathomechanism of liver fibrosis: targeting chemokine CCL2-mediated HIV:HCV nexus

Even in the era of successful combination antiretroviral therapy (cART), co-infection of Hepatitis C virus (HCV) remains one of the leading causes of non-AIDS-related mortality and morbidity among HIV-positive individuals as a consequence of accelerated liver fibrosis and end-stage liver disease (ESLD). The perturbed liver microenvironment and induction of host pro-inflammatory mediators in response to HIV and HCV infections, play a pivotal role in orchestrating the disease pathogenesis and clinical outcomes. How these viruses communicate each other via chemokine CCL2 and exploit the liver specific cellular environment to exacerbate liver fibrosis in HIV/HCV co-infection setting is a topic of intense discussion. Herein, we provide recent views and insights on potential mechanisms of CCL2 mediated immuno-pathogenesis, and HIV-HCV cross-talk in driving liver inflammation. We believe CCL2 may potentially serve an attractive target of anti-fibrotic intervention against HIV/HCV co-infection associated co-morbidities.

Hepatitis C virus core protein enhances HIV-1 replication in human macrophages through TLR2, JNK, and MEK1/2-dependent upregulation of TNF-α and IL-6

Despite their differential cell tropisms, HIV-1 and HCV dramatically influence disease progression in coinfected patients. Macrophages are important target cells of HIV-1. We hypothesized that secreted HCV core protein might modulate HIV-1 replication. We demonstrate that HCV core significantly enhances HIV-1 replication in human macrophages by upregulating TNF-α and IL-6 via TLR2-, JNK-, and MEK1/2-dependent pathways. Furthermore, we show that TNF-α and IL-6 secreted from HCV core-treated macrophages reactivates monocytic U1 cells latently infected with HIV-1. Our studies reveal a previously unrecognized role of HCV core by enhancing HIV-1 infection in macrophages.

Do the epidemiology, physiological mechanisms and characteristics of hepatocellular carcinoma in HIV-infected patients justify specific screening policies?

Reducing the incidence of hepatocellular carcinoma (HCC) in HIV-infected patients has become a serious problem when managing these patients. There are many explanations for this disease evolution, which notably include their longer survival under effective antiviral therapy and also the more rapid evolution of chronic liver disease. Despite recent advances in the management of hepatitis B (HBV) and hepatitis C (HCV) viral diseases, which will probably increase the number of patients achieving a virological response, HIV-infected patients with cirrhosis are still at risk of the onset of HCC. This evolution to HCC is also correlated to other comorbidities such as excessive alcohol consumption and nonalcoholic steatohepatitis (NASH). HCC thus remains a public health issue in this population. The poor prognosis and aggressiveness of HCC have been fully demonstrated, but the mechanisms underlying this aggressiveness are not yet well defined. As well as underlying mechanisms that contribute to accelerating hepatocarcinogenesis in HIV-infected patients, there are other reasons why HIV-infected patients should be considered a higher risk population. This review discusses the principal epidemiological determinants; the mechanisms of pathogenesis; and the treatment of HCC in HIV/HBV and HIV/HCV coinfected patients. It also discusses the probable need to develop a specific screening policy for HCC in this population in order to prevent the rapid development and to make them more amenable to a curative treatment.