Hepatitis C virus-specific Th17 cells are suppressed by virus-induced TGF-beta

Biomarkers in Detection of Hepatitis C Virus Infection

The hepatitis C virus (HCV) infection affects 58 million people worldwide. In the United States, the incidence rate of acute hepatitis C has doubled since 2014; during 2021, this increased to 5% from 2020. Acute hepatitis C is defined by any symptom of acute viral hepatitis plus either jaundice or elevated serum alanine aminotransferase (ALT) activity with the detection of HCV RNA, the anti-HCV antibody, or hepatitis C virus antigen(s). However, most patients with acute infection are asymptomatic. In addition, ALT activity and HCV RNA levels can fluctuate, and a delayed detection of the anti-HCV antibody can occur among some immunocompromised persons with HCV infection. The detection of specific biomarkers can be of great value in the early detection of HCV infection at an asymptomatic stage. The high rate of HCV replication (which is approximately 1010 to 1012 virions per day) and the lack of proofreading by the viral RNA polymerase leads to enormous genetic diversity, creating a major challenge for the host immune response. This broad genetic diversity contributes to the likelihood of developing chronic infection, thus leading to the development of cirrhosis and liver cancer. Direct-acting antiviral (DAA) therapies for HCV infection are highly effective with a cure rate of up to 99%. At the same time, many patients with HCV infection are unaware of their infection status because of the mostly asymptomatic nature of hepatitis C, so they remain undiagnosed until the liver damage has advanced. Molecular mechanisms induced by HCV have been intensely investigated to find biomarkers for diagnosing the acute and chronic phases of the infection. However, there are no clinically verified biomarkers for patients with hepatitis C. In this review, we discuss the biomarkers that can differentiate acute from chronic hepatitis C, and we summarize the current state of the literature on the useful biomarkers that are detectable during acute and chronic HCV infection, liver fibrosis/cirrhosis, and hepatocellular carcinoma (HCC).

The Role of Interleukins in HBV Infection: A Narrative Review

Hepatitis B virus (HBV) infection is a worldwide medical issue with significant morbidity and mortality, as it is the main cause of chronic liver disease and hepatocellular carcinoma (HCC). Both innate and adaptive immune responses play a key role in HBV replication and suppression. Recently, the pathophysiological function of interleukins (IL) in the natural course of HBV has gained much attention as a result of the broad use of anti-interleukin agents for a variety of autoimmune diseases and the accompanying risk of HBV reactivation. We present a narrative review regarding the role of IL in HBV infection. Collectively, the pro-inflammatory ILs, namely IL-1, IL-5, IL-6, IL-12 and IL-21, seem to play a critical role in the suppression of HBV replication. In contrast, the anti-inflammatory cytokines IL-10, IL-23 and IL-35 probably act as HBV replication enhancers, while IL-17 has been correlated with HBV-related liver injury. Interestingly enough, IL-2, IL-4 and IL-12 have been tried as therapeutic options against HBV infection with contradictory results. Lastly, the role of IL-22 remains largely ill defined, although preliminary data suggest that it may play a significant role in HBV replication, proliferation and subsequent liver damage.

The IL-17 family in diseases: from bench to bedside

The interleukin-17 (IL-17) family comprises six members (IL-17A-17F), and recently, all of its related receptors have been discovered. IL-17 was first discovered approximately 30 years ago. Members of this family have various biological functions, including driving an inflammatory cascade during infections and autoimmune diseases, as well as boosting protective immunity against various pathogens. IL-17 is a highly versatile proinflammatory cytokine necessary for vital processes including host immune defenses, tissue repair, inflammatory disease pathogenesis, and cancer progression. However, how IL-17 performs these functions remains controversial. The multifunctional properties of IL-17 have attracted research interest, and emerging data have gradually improved our understanding of the IL-17 signaling pathway. However, a comprehensive review is required to understand its role in both host defense functions and pathogenesis in the body. This review can aid researchers in better understanding the mechanisms underlying IL-17's roles in vivo and provide a theoretical basis for future studies aiming to regulate IL-17 expression and function. This review discusses recent progress in understanding the IL-17 signaling pathway and its physiological roles. In addition, we present the mechanism underlying IL-17's role in various pathologies, particularly, in IL-17-induced systemic lupus erythematosus and IL-17-related tumor cell transformation and metastasis. In addition, we have briefly discussed promising developments in the diagnosis and treatment of autoimmune diseases and tumors.

Friend or Foe - Tc17 cell generation and current evidence for their importance in human disease

The term Tc17 cells refers to interleukin 17 (IL-17)-producing CD8+ T cells. While IL-17 is an important mediator of mucosal defense, it is also centrally involved in driving the inflammatory response in immune-mediated diseases, such as psoriasis, multiple sclerosis, and inflammatory bowel disease. In this review, we aim to gather the current knowledge on the phenotypic and transcriptional profile, the in vitro and in vivo generation of Tc17 cells, and the evidence pointing towards a relevant role of Tc17 cells in human diseases such as infectious diseases, cancer, and immune-mediated diseases.

IL-17 and IL-17-producing cells in protection versus pathology

IL-17 cytokine family members have diverse biological functions, promoting protective immunity against many pathogens but also driving inflammatory pathology during infection and autoimmunity. IL-17A and IL-17F are produced by CD4⁺ and CD8⁺ T cells, γδ T cells, and various innate immune cell populations in response to IL-1β and IL-23, and they mediate protective immunity against fungi and bacteria by promoting neutrophil recruitment, antimicrobial peptide production and enhanced barrier function. IL-17-driven inflammation is normally controlled by regulatory T cells and the anti-inflammatory cytokines IL-10, TGFβ and IL-35. However, if dysregulated, IL-17 responses can promote immunopathology in the context of infection or autoimmunity. Moreover, IL-17 has been implicated in the pathogenesis of many other disorders with an inflammatory basis, including cardiovascular and neurological diseases. Consequently, the IL-17 pathway is now a key drug target in many autoimmune and chronic inflammatory disorders; therapeutic monoclonal antibodies targeting IL-17A, both IL-17A and IL-17F, the IL-17 receptor, or IL-23 are highly effective in some of these diseases. However, new approaches are needed to specifically regulate IL-17-mediated immunopathology in chronic inflammation and autoimmunity without compromising protective immunity to infection.

TGF-β from the Porcine Intestinal Cell Line IPEC-J2 Induced by Porcine Circovirus 2 Increases the Frequency of Treg Cells via the Activation of ERK (in CD4+ T Cells) and NF-κB (in IPEC-J2)

Porcine circovirus 2 (PCV2) causes immunosuppression. Piglets infected with PCV2 can develop enteritis. Given that the gut is the largest immune organ, however, the response of the gut's immune system to PCV2 is still unclear. Here, IPEC-J2 cells with different treatments were co-cultured with PBMC or CD4⁺ T cells (Transwell). Flow cytometry and Western blotting revealed that PCV2-infected IPEC-J2 increased the frequency of CD4⁺ T cells among piglets' peripheral blood mononuclear cells (PBMCs) and caused CD4⁺ T cells to undergo a transformation into Foxp3⁺ regulatory T cells (Treg cells) via activating CD4⁺ T ERK. Cytokines production and an inhibitor assay showed that the induction of Tregs by PCV2-infected IPEC-J2 was dependent on TGF-β induced by PCV2 in IPEC-J2, which was associated with the activation of NF-κB. Taken together, PCV2-infected IPEC-J2 activated NF-κB to stimulate the synthesis of TGF-β, which enhanced the differentiation of CD4⁺ T cells into Treg cells through the activation of ERK in CD4⁺ T cells. This information sheds light on PCV2's function in the intestinal immune system and suggests a potential immunosuppressive mechanism for PCV2 infection.

Murine cytomegalovirus promotes renal allograft inflammation via Th1/17 cells and IL-17A

Human cytomegalovirus (HCMV) infection is associated with renal allograft failure. Allograft damage in animal models is accelerated by CMV-induced T helper 17 (Th17) cell infiltrates. However, the mechanisms whereby CMV promotes Th17 cell-mediated pathological organ inflammation are uncharacterized. Here we demonstrate that murine CMV (MCMV)-induced intragraft Th17 cells have a Th1/17 phenotype co-expressing IFN-γ and/or TNF-α, but only a minority of these cells are MCMV specific. Instead, MCMV promotes intragraft expression of CCL20 and CXCL10, which are associated with recruitment of CCR6⁺ CXCR3⁺ Th17 cells. MCMV also enhances Th17 cell infiltrates after ischemia-reperfusion injury, independent of allogeneic responses. Pharmacologic inhibition of the Th17 cell signature cytokine, IL-17A, ameliorates MCMV-associated allograft damage without increasing intragraft viral loads or reducing MCMV-specific Th1 cell infiltrates. Clinically, HCMV DNAemia is associated with higher serum IL-17A among renal transplant patients with acute rejection, linking HCMV reactivation with Th17 cell cytokine expression. In summary, CMV promotes allograft damage via cytokine-mediated Th1/17 cell recruitment, which may be pharmacologically targeted to mitigate graft injury while preserving antiviral T cell immunity.

Uncovering Resistance to Hepatitis C Virus Infection: Scientific Contributions and Unanswered Questions in the Irish Anti-D Cohort

Infections caused inadvertently during clinical intervention provide valuable insight into the spectrum of human responses to viruses. Delivery of hepatitis C virus (HCV)-contaminated blood products in the 70s (before HCV was identified) have dramatically increased our understanding of the natural history of HCV infection and the role that host immunity plays in the outcome to viral infection. In Ireland, HCV-contaminated anti-D immunoglobulin (Ig) preparations were administered to approximately 1700 pregnant Irish rhesus-negative women in 1977–1979. Though tragic in nature, this outbreak (alongside a smaller episode in 1993) has provided unique insight into the host factors that influence outcomes after HCV exposure and the subsequent development of disease in an otherwise healthy female population. Despite exposure to highly infectious batches of anti-D, almost 600 of the HCV-exposed women have never shown any evidence of infection (remaining negative for both viral RNA and anti-HCV antibodies). Detailed analysis of these individuals may shed light on innate immune pathways that effectively block HCV infection and potentially inform us more generally about the mechanisms that contribute to viral resistance in human populations.

Interleukin-17A pretreatment attenuates the anti-hepatitis B virus efficacy of interferon-alpha by reducing activation of the interferon-stimulated gene factor 3 transcriptional complex in hepatitis B virus-expressing HepG2 cells

Background

Some cytokine signaling pathways can interact with interferon (IFN)-α pathway and thus regulate cell responses to IFN-α. Levels of the pro-inflammatory cytokine interleukin-17A (IL-17A) were found to be elevated in both the peripheral blood and liver in chronic hepatitis B (CHB) patients. However, how IL-17A affects the anti-HBV activity of IFN-α remains unclear.

Methods

The effects of IL-17A on anti-HBV activity of IFN-α were evaluated in HBV-expressing HepG2 cells (HepG2-HBV1.3) with IL-17A pretreatment and IFN-α stimulation. Culture supernatant levels of HBsAg, HBeAg, and HBV DNA, or intracellular expression of HBsAg and HBcAg were detected by ELISA, real-time quantitative PCR (RT-qPCR), or western blotting (WB). The expression of canonical IFN-α signaling pathway components, including the interferon-α/β receptor (IFNAR), Janus Kinase 1 (JAK1), Tyrosine Kinase 2 (TYK2), the Interferon Stimulated Gene Factor 3 complex (ISGF3) and IFN-stimulated genes (ISGs), was also examined by RT-qPCR, Immunofluorescence or WB. The effects of IL-17A were further investigated by the suppression of the IL-17A pathway with a TRAF6 inhibitor.

Results

Compared to IFN-α stimulation alone, IL-17A pretreatment followed by IFN-α stimulation increased the levels of HBsAg, HBeAg, and HBV DNA, and decreased the levels of ISGF3 complex (phosphorylated (p)-signal transducer and activator of transcription (STAT1)/p-STAT2/IRF9) and antiviral-related ISGs (ISG15, ISG20 and Mx1). Interestingly, IL-17A pretreatment increased the expression of suppressor of cytokine signaling (SOCS) 1, SOCS3 and USP18, which were also the ISGs negatively regulating activity of ISGF3. Moreover, IFNAR1 protein expression declined more sharply in the group with IL-17A pretreatment than in the group with IFN-α stimulation alone. Blocking the IL-17A pathway reversed the effects of IL-17A on the IFN-α-induced activation of ISGF3 and anti-HBV efficacy.

Conclusions

Our results demonstrate that IL-17A pretreatment could attenuate IFN-α-induced anti-HBV activity by upregulating negative regulators of the critical transcriptional ISGF3 complex. Thus, this might be a potential target for improving response to IFN-α therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01753-x.

Active Module Identification From Multilayer Weighted Gene Co-Expression Networks: A Continuous Optimization Approach

Searching for active modules, i.e., regions showing striking changes in molecular activity in biological networks is important to reveal regulatory and signaling mechanisms of biological systems. Most existing active modules identification methods are based on protein-protein interaction networks or metabolic networks, which require comprehensive and accurate prior knowledge. On the other hand, weighted gene co-expression networks (WGCNs) are purely constructed from gene expression profiles. However, existing WGCN analysis methods are designed for identifying functional modules but not capable of identifying active modules. There is an urgent need to develop an active module identification algorithm for WGCNs to discover regulatory and signaling mechanism associating with a given cellular response. To address this urgent need, we propose a novel algorithm called active modules on the multi-layer weighted (co-expression gene) network, based on a continuous optimization approach (AMOUNTAIN). The algorithm is capable of identifying active modules not only from single-layer WGCNs but also from multilayer WGCNs such as cross-species and dynamic WGCNs. We first validate AMOUNTAIN on a synthetic benchmark dataset. We then apply AMOUNTAIN to WGCNs constructed from Th17 differentiation gene expression datasets of human and mouse, which include a single layer, a cross-species two-layer and a multilayer dynamic WGCNs. The identified active modules from WGCNs are enriched by known protein-protein interactions, and more importantly, they reveal some interesting and important regulatory and signaling mechanisms of Th17 cell differentiation.

The multi-faceted roles of TGF-β in regulation of immunity to infection

Transforming Growth Factor-β is a potent regulator of the immune system, acting at every stage from thymic differentiation, population of the periphery, control of responsiveness, tissue repair and generation of memory. It is therefore a central player in the immune response to infectious pathogens, but its contribution is often clouded by multiple roles acting on different cells in time and space. Hence, context is all-important in understanding when TGF-β is beneficial or detrimental to the outcome of infection. In this review, a full range of infectious agents from viruses to helminth parasites are explored within this framework, drawing contrasts and general conclusions about the importance of TGF-β in these diseases.

Crosstalk of Microorganisms and Immune Responses in Autoimmune Neuroinflammation: A Focus on Regulatory T Cells

Regulatory T cells (Tregs) are the major determinant of peripheral immune tolerance. Many Treg subsets have been described, however thymus-derived and peripherally induced Tregs remain the most important subpopulations. In multiple sclerosis, a prototypical autoimmune disorder of the central nervous system, Treg dysfunction is a pathogenic hallmark. In contrast, induction of Treg proliferation and enhancement of their function are central immune evasion mechanisms of infectious pathogens. In accordance, Treg expansion is compartmentalized to tissues with high viral replication and prolonged in chronic infections. In friend retrovirus infection, Treg expansion is mainly based on excessive interleukin-2 production by infected effector T cells. Moreover, pathogens seem also to enhance Treg functions as shown in human immunodeficiency virus infection, where Tregs express higher levels of effector molecules such as cytotoxic T-lymphocyte-associated protein 4, CD39 and cAMP and show increased suppressive capacity. Thus, insights into the molecular mechanisms by which intracellular pathogens alter Treg functions might aid to find new therapeutic approaches to target central nervous system autoimmunity. In this review, we summarize the current knowledge of the role of pathogens for Treg function in the context of autoimmune neuroinflammation. We discuss the mechanistic implications for future therapies and provide an outlook for new research directions.

Host immune response in chronic hepatitis C infection: involvement of cytokines and inflammasomes

Chronic liver disease is a major health issue worldwide and chronic hepatitis C (CHC) is associated with an increased risk of cirrhosis and hepatocellular carcinoma (HCC). There is evidence that the hepatitis C virus (HCV) infection is correlated with immune senescence by way of immune activation and chronic inflammation, which lead to increased metabolic and cardiovascular risk, as well as progressive liver damage. Both the innate and adaptive immunity are firmly tied to the prognosis of an infection with HCV and its response to antiviral therapy. HCV is therefore associated with increased pro-inflammatory status, heightened production of cytokines, prolonged systemic inflammation, as well as increased morbidity and mortality, mainly due to the progression of hepatic fibrosis and HCC, but also secondary to cardiovascular diseases. Viral hepatic pathology is increasingly considered a disease that is no longer merely limited to the liver, but one with multiple metabolic consequences. Numerous in vitro studies, using experimental models of acute or chronic inflammation of the liver, has brought new information on immunopathological mechanisms resulting from viral infections and have highlighted the importance of involving complex structures, inflammasomes complex, in these mechanisms, in addition to the involvement of numerous proinflammatory cytokines. Beyond obtaining a sustained viral response and halting the aforementioned hepatic fibrosis, the current therapeutic “treat-to-target” strategies are presently focused on immune-mediated and metabolic disorders, to improve the quality of life and long-term prognosis of CHC patients.

Lipid homeostasis and mevalonate pathway in COVID-19: Basic concepts and potential therapeutic targets

Despite encouraging progresses achieved in the management of viral diseases, efficient strategies to counteract infections are still required. The current global challenge highlighted the need to develop a rapid and cost-effective strategy to counteract the SARS-CoV-2 pandemic. Lipid metabolism plays a crucial role in viral infections. Viruses can use the host lipid machinery to support their life cycle and to impair the host immune response. The altered expression of mevalonate pathway-related genes, induced by several viruses, assures survival and spread in host tissue. In some infections, statins, HMG-CoA-reductase inhibitors, reduce cholesterol in the plasma membrane of permissive cells resulting in lower viral titers and failure to internalize the virus. Statins can also counteract viral infections through their immunomodulatory, anti-inflammatory and anti-thrombotic effects. Beyond statins, interfering with the mevalonate pathway could have an adjuvant effect in therapies aimed at mitigating endothelial dysfunction and deregulated inflammation in viral infection. In this review we depicted the historical and current evidence highlighting how lipid homeostasis and mevalonate pathway targeting represents a valid approach to rapidly neutralize viruses, focusing our attention to their potential use as effective targets to hinder SARS-CoV-2 morbidity and mortality. Pros and cons of statins and Mevalonate-pathway inhibitors have been also dissected.

CD8+CD161+ T-Cells: Cytotoxic Memory Cells With High Therapeutic Potential

NK1.1 and its human homolog CD161 are expressed on NK cells, subsets of CD4⁺ and CD8⁺ T cells, and NKT cells. While the expression of NK1.1 is thought to be inhibitory to NK cell function, it is reported to play both costimulatory and coinhibitory roles in T-cells. CD161 has been extensively studied and characterized on subsets of T-cells that are MR1-restricted, IL-17 producing CD4⁺ (T_H17 MAIT cells) and CD8⁺ T cells (Tc17 cells). Non-MAIT, MR1-independent CD161-expressing T-cells also exist and are characterized as generally effector memory cells with a stem cell like phenotype. Gene expression analysis of this enigmatic subset indicates a significant enhancement in the expression of cytotoxic granzyme molecules and innate like stress receptors in CD8⁺NK1.1⁺/CD8⁺CD161⁺ cells in comparison to CD8⁺ cells that do not express NK1.1 or CD161. First identified and studied in the context of viral infection, the role of CD8⁺CD161⁺ T-cells, especially in the context of tumor immunology, is still poorly understood. In this review, the functional characteristics of the CD161-expressing CD8⁺ T cell subset with respect to gene expression profile, cytotoxicity, and tissue homing properties are discussed, and application of this subset to immune responses against infectious disease and cancer is considered.

Characterization of the IL-17 and CD4+ Th17 Cells in the Clinical Course of Dengue Virus Infections

The aims of this study were to determine the involvement of interleukin 17 (IL-17) and IL-17-producing cells in dengue pathogenesis. Blood samples from dengue virus (DENV)-infected patients were collected on different days after the onset of symptoms. Patients were classified according to 1997 World Health Organization guidelines. Our study examined 152 blood samples from dengue fever (DF, n = 109) and dengue hemorrhagic fever (DHF, n = 43) patients and 90 blood samples from healthy controls (HC). High serum concentrations of IL-17A and IL-22 were also associated with DHF (IL-17A [DHF vs. DF, p < 0.01; DHF vs. HC, p < 0.0001]; IL-22 [DHF vs. DF, p < 0.05; DHF vs. HC, p < 0.0001]). Moreover, there was a positive correlation between serum levels of IL-17A and IL-23, a key cytokine that promotes IL-17-based immune responses (r = 0.4089, p < 0.0001). Consistent with the IL-17-biased immune response in DHF patients, we performed ex vivo activation of peripheral blood mononuclear cells (PBMCs) from DHF patients and flow cytometry analysis showed a robust IL-17-biased immune response, characterized by a high frequency of CD4+IL-17+ producing cells. Our results suggests IL-17-producing cells and their related cytokines can play a prominent role in this viral disease.

Identification of the association of CD28+ CD244+ Tc17/IFN-γ cells with chronic hepatitis C virus infection

CD8+ T cells play multiple and complex immunological roles including antiviral, regulatory, and exhaustive effects in hepatitis C virus (HCV) infected patients. Some CD8+ T-cell subsets were confirmed to be closely related to HCV infection such as TCM , TEM , TEM RA, Tc17, and CD8+ Treg. Herein, we report a new subset of interleukin (IL)-17/interferon (IFN)-γ producing CD8+ T (Tc17/IFN-γ) cells that markedly correlate with CD28+ CD244+ cells, IL-17 levels, and HCV RNA in HCV patients. During early treatment with peg-IFN-a2a plus ribavirin, the imbalance of these Tc17/IFN-γ cells could be partially restored, together with normalized serum alanine aminotransferase but not aspartate transaminase. Also, we analyzed the dynamic change of the percentage of this T cells subset in patients with different outcome after 4-week course of treatment with peg-IFN-a2a plus ribavirin and found that the percentage of CD8+ CD28+ CD244+ T cells significantly decreased in recovered patients but not in nonrecovered patients. In vitro, CD28+ CD244+ T cells were the only CD8+ T-cell group that secreted both IL-17 and IFN-γ in this axis and blockade with anti-CD244 antibodies significantly reduced cytokine production. Taken together, this study demonstrates that the frequency and regulatory functions of CD28+ CD244+ Tc17/IFN-γ cells may play an important role in persistent HCV infection.

Pathophysiology and potential future therapeutic targets using preclinical models of COVID-19

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) gains entry into the lung epithelial cells by binding to the surface protein angiotensin-converting enzyme 2. Severe SARS-CoV-2 infection, also known as coronavirus disease 2019 (COVID-19), can lead to death due to acute respiratory distress syndrome mediated by inflammatory immune cells and cytokines. In this review, we discuss the molecular and biochemical bases of the interaction between SARS-CoV-2 and human cells, and in doing so we highlight knowledge gaps currently precluding development of new effective therapies. In particular, discovery of novel treatment targets in COVID-19 will start from understanding pathologic changes based on a large number of autopsy lung tissue samples. Pathogenetic roles of potential molecular targets identified in human lung tissues must be validated in established animal models. Overall, this stepwise approach will enable appropriate selection of candidate therapeutic modalities targeting SARS-CoV2 and the host inflammatory response.

Cell-to-cell spread of vaccinia virus is promoted by TGF-β-independent Smad4 signalling

The induction of Smad signalling by the extracellular ligand TGF-β promotes tissue plasticity and cell migration in developmental and pathological contexts. Here, we show that vaccinia virus (VACV) stimulates the activity of Smad transcription factors and expression of TGF-β/Smad-responsive genes at the transcript and protein levels. Accordingly, infected cells share characteristics to those undergoing TGF-β/Smad-mediated epithelial-to-mesenchymal transition (EMT). Depletion of the Smad4 protein, a common mediator of TGF-β signalling, results in an attenuation of viral cell-to-cell spread and reduced motility of infected cells. VACV induction of TGF-β/Smad-responsive gene expression does not require the TGF-β ligand or type I and type II TGF-β receptors, suggesting a novel, non-canonical Smad signalling pathway. Additionally, the spread of ectromelia virus, a related orthopoxvirus that does not activate a TGF-β/Smad response, is enhanced by the addition of exogenous TGF-β. Together, our results indicate that VACV orchestrates a TGF-β-like response via a unique activation mechanism to enhance cell migration and promote virus spread.

Influence of hepatitis C virus eradication with direct-acting antivirals on the gut microbiota in patients with cirrhosis

BACKGROUND

The cure of hepatitis C virus (HCV) infection may contribute to the reduction of liver fibrosis progression and potentially influence the gut-liver axis.

AIM

To investigate the influence of HCV infection eradication with direct-acting antivirals (DAAs) on the gut microbiota composition as well as on intestinal and systemic inflammatory parameters in patients with cirrhosis.

METHODS

Consecutive patients with HCV-related cirrhosis receiving DAA treatment were included. The gut microbiota composition, intestinal permeability, and inflammation were assessed before treatment and after 1 year. Clinical outcomes such as episodes of decompensation and markers of liver fibrosis were evaluated over a 2-year follow-up period.

RESULTS

The gut microbiota alpha diversity in cirrhotic patients, which was lower than that in healthy subjects, was significantly improved by the cure of HCV infection and a shift in the overall gut microbiota composition was observed compared to baseline. The abundance of potentially pathogenic bacteria (Enterobacteriaceae, Enterococcus, and Staphylococcus) was decreased after treatment. The gut microbiota composition was associated with the inflammatory profile and markers of liver fibrosis. Although a significant reduction in the serum levels of cytokines and chemokines was observed post-DAA treatment, measures of intestinal permeability and inflammation remained unchanged.

CONCLUSIONS

Cure of HCV infection with DAAs in patients with cirrhosis is associated with a modification of the gut microbiota, which correlates with fibrosis and inflammation but does not improve intestinal barrier function.

Mononuclear phagocyte system in hepatitis C virus infection

The mononuclear phagocyte system (MPS), which consists of monocytes, dendritic cells (DCs), and macrophages, plays a vital role in the innate immune defense against pathogens. Hepatitis C virus (HCV) is efficient in evading the host immunity, thereby facilitating its development into chronic infection. Chronic HCV infection is the leading cause of end-stage liver diseases, liver cirrhosis, and hepatocellular carcinoma. Acquired immune response was regarded as the key factor to eradicate HCV. However, innate immunity can regulate the acquired immune response. Innate immunity-derived cytokines shape the adaptive immunity by regulating T-cell differentiation, which determines the outcome of acute HCV infection. Inhibition of HCV-specific T-cell responses is one of the most important strategies for immune system evasion. It is meaningful to illustrate the role of innate immune response in HCV infection. With the MPS being the important factor in innate immunity, therefore, understanding the role of the MPS in HCV infection will shed light on the pathophysiology of chronic HCV infection. In this review, we outline the impact of HCV infection on the MPS and cytokine production. We discuss how HCV is detected by the MPS and describe the function and impairment of MPS components in HCV infection.

Peripheral lymphocytes analyses in children with chronic hepatitis C virus infection

BACKGROUND

Hepatitis C virus (HCV)-specific immune response is believed to play a crucial role in viral clearance. There is, nevertheless, no reliable parameter to monitor this immune response or predict chronic HCV infection development.

METHOD

An observational case-control study was performed to identify such parameters, peripheral blood mononuclear cells from 57 children with chronic HCV were systemically phenotyped, and the serum level of Interferon gamma and interleukin (IL) -17 was measured. The data were compared with 37 age-matched healthy volunteers (controls).

RESULTS

Children with chronic HCV infection had a lower frequency of natural killer cells (NK) cells, CD56Dim NK cells and expansion of CD56Bright NK cells compared with controls (P = 0.001, P < 0.0001 and P < 0.0001 respectively). Increased CD56Dim NK cells were negatively correlated with the higher viral load, R²  = 0.29, P = 0.05, while, increased NK T cells were positively correlated with high viral load, R²  = 0.17, P = 0.011. T helper cells, naive T cells, CD127 negative T cells, and HLA-DR-positive T cells significantly increased in patients than in controls. The frequency of CD4+CD25high+ T regulatory (Treg) cells increased in HCV-infected patients, compared with those in control, and FOXP3 was upregulated within them. Treg cells' increase was positively correlated with high viral load, R²  = 0.45, P = 0.004. The level of IL-17 was higher in HCV patients than that in control, P < 0.0001.

CONCLUSION

Although the contribution of those markers to the chronic HCV establishment in children remains elusive, the results may provide important clues for reliable indicators of HCV infection.

Louis I, Schiff LA, Bohjanen PR. Reovirus infection induces stabilization and up-regulation of cellular transcripts that encode regulators of TGF-β signaling

Reovirus infection induces dramatic changes in host mRNA expression. We utilized oligonucleotide microarrays to measure cellular mRNA decay rates in mock- or reovirus-infected murine L929 cells to determine if changes in host mRNA expression are a consequence of reovirus-induced alterations in cellular mRNA stability. Our analysis detected a subset of cellular transcripts that were coordinately induced and stabilized following infection with the reovirus isolates c87 and c8, strains that led to an inhibition of cellular translation, but not following infection with Dearing, a reovirus isolate that did not negatively impact cellular translation. The induced and stabilized transcripts encode multiple regulators of TGF- β signaling, including components of the Smad signaling network and apoptosis/survival pathways. The coordinate induction, through mRNA stabilization, of multiple genes that encode components of TGF-β signaling pathways represents a novel mechanism by which the host cell responds to reovirus infection.

Regulation of the Immune Response by TGF-β: From Conception to Autoimmunity and Infection

Transforming growth factor β (TGF-β) is a pleiotropic cytokine involved in both suppressive and inflammatory immune responses. After 30 years of intense study, we have only begun to elucidate how TGF-β alters immunity under various conditions. Under steady-state conditions, TGF-β regulates thymic T-cell selection and maintains homeostasis of the naïve T-cell pool. TGF-β inhibits cytotoxic T lymphocyte (CTL), Th1-, and Th2-cell differentiation while promoting peripheral (p)Treg-, Th17-, Th9-, and Tfh-cell generation, and T-cell tissue residence in response to immune challenges. Similarly, TGF-β controls the proliferation, survival, activation, and differentiation of B cells, as well as the development and functions of innate cells, including natural killer (NK) cells, macrophages, dendritic cells, and granulocytes. Collectively, TGF-β plays a pivotal role in maintaining peripheral tolerance against self- and innocuous antigens, such as food, commensal bacteria, and fetal alloantigens, and in controlling immune responses to pathogens.

Interplay of Regulatory T Cell and Th17 Cells during Infectious Diseases in Humans and Animals

It is now clear that the outcome of an inflammatory process caused by infections depends on the balance of responses by several components of the immune system. Of particular relevance is the interplay between regulatory T cells (Tregs) and CD4⁺ T cells that produce IL-17 (Th17 cells) during immunoinflammatory events. In addition to discussing studies done in mice to highlight some unresolved issues in the biology of these cells, we emphasize the need to include outbred animals and humans in analyses. Achieving a balance between Treg and Th17 cells responses represents a powerful approach to control events during immunity and immunopathology.

Metabolic Inflammation-Associated IL-17A Causes Non-alcoholic Steatohepatitis and Hepatocellular Carcinoma

Obesity increases hepatocellular carcinoma (HCC) risks via unknown mediators. We report that hepatic unconventional prefoldin RPB5 interactor (URI) couples nutrient surpluses to inflammation and non-alcoholic steatohepatitis (NASH), a common cause of HCC. URI-induced DNA damage in hepatocytes triggers inflammation via T helper 17 (Th17) lymphocytes and interleukin 17A (IL-17A). This induces white adipose tissue neutrophil infiltration mediating insulin resistance (IR) and fatty acid release, stored in liver as triglycerides, causing NASH. NASH and subsequently HCC are prevented by pharmacological suppression of Th17 cell differentiation, IL-17A blocking antibodies, and genetic ablation of the IL-17A receptor in myeloid cells. Human hepatitis, fatty liver, and viral hepatitis-associated HCC exhibit increased IL-17A correlating positively with steatosis. IL-17A blockers may prevent IR, NASH, and HCC in high-risk patients.

HCV Specific IL-21 Producing T Cells but Not IL-17A Producing T Cells Are Associated with HCV Viral Control in HIV/HCV Coinfection

BACKGROUND

Decreased hepatitis C virus (HCV) clearance, faster cirrhosis progression and higher HCV RNA levels are associated with Human Immunodeficiency virus (HIV) coinfection. The CD4+ T helper cytokines interleukin (IL)-21 and IL-17A are associated with virus control and inflammation, respectively, both important in HCV and HIV disease progression. Here, we examined how antigen-specific production of these cytokines during HCV mono and HIV/HCV coinfection was associated with HCV virus control.

METHODS

We measured HCV-specific IL-21 and IL-17A production by transwell cytokine secretion assay in PBMCs from monoinfected and coinfected individuals. Viral control was determined by plasma HCV RNA levels.

RESULTS

In acutely infected individuals, those able to establish transient/complete HCV viral control tended to have stronger HCV-specific IL-21-production than non-controllers. HCV-specific IL-21 production also correlated with HCV viral decline in acute infection. Significantly stronger HCV-specific IL-21 production was detected in HAART-treated coinfected individuals. HCV-specific IL-17A production was not associated with lower plasma HCV RNA levels in acute or chronic HCV infection and responses were stronger in HIV coinfection. HCV-specific IL-21/ IL-17A responses did not correlate with microbial translocation or fibrosis. Exogenous IL-21 treatment of HCV-specific CD8+ T cells from monoinfected individuals enhanced their function although CD8+ T cells from coinfected individuals were somewhat refractory to the effects of IL-21.

CONCLUSIONS

These data show that HCV-specific IL-21 and IL-17A-producing T cells are induced in HIV/HCV coinfection. In early HIV/HCV coinfection, IL-21 may contribute to viral control, and may represent a novel tool to enhance acute HCV clearance in HIV/HCV coinfected individuals.

The Interplay between Zinc, Vitamin D and, IL-17 in Patients with Chronic Hepatitis C Liver Disease

Objectives. To assess zinc (Zn) and vitamin D (Vit. D) status in chronic Hepatitis C virus- (HCV) infected patients and their relationship to interleukin- (IL-) 17 and disease severity and then investigate whether Zn and Vit. D3 modulate IL-17 expression in chronic HCV patients. Methods. Seventy patients and fifty healthy subjects were investigated. Serum levels of Zn, Vit. D, and IL-17 were assessed in the patients group and subgroups. Patients lymphocytes were activated in vitro in the presence or absence of Zn or Vit. D3 and then intracellular IL-17 production was assessed using flow cytometry. Results. Zn and Vit. D were significantly decreased in HCV patients. Increasing disease severity leads to more reduction in Zn level opposed by increasing IL-17 level. Zn potently reduced IL-17 production in a dose-related fashion; however it did not exert any toxic effects. Although Vit. D apparently increases IL17 expression, it is unclear whether it is due to its toxic effect on cell count or lack of definite association between Vit. D and both IL-17 and disease severity. Conclusions. This study demonstrates that Zn modulates IL-17 expression and provides a rationale for evaluating this compound as a supplementary agent in the treatment of chronic HCV.

The role of interleukin-17 in intrahepatic cholestasis of pregnancy

OBJECTIVE

Intrahepatic cholestasis of pregnancy (ICP) is the most common pregnancy-specific liver disease, is characterized by pruritus, abnormal liver function and elevated serum bile acid levels. The main cause of ICP has not yet been identified. We aimed to provide a new perspective to the pathogenesis of by investigating the possible association of circulating interleukin-17 (IL-17) that is a recently discovered proinflammatory cytokine levels with ICP.

MATERIALS AND METHODS

In this controlled cross-sectional study, maternal venous blood samples were obtained from 33 consecutive pregnant women with ICP (15 with mild and 18 with severe forms of the disease) and 25 healthy women with uncomplicated pregnancies (as the control group) and IL-17 levels were compared among the groups.

RESULTS

Although serum IL-17 levels were significantly higher in the severe ICP group than in the control group (p = 0.022), there were no significant differences between the mild and severe ICP groups or between the control and mild ICP groups.

CONCLUSION

Explaining the mechanisms of hepatocyte injury might contribute to the existing therapeutic strategies for treating cholestatic diseases. Changes in IL-17 levels may shed light on the pathogenesis of ICP.

Circulating FoxP3+ Regulatory T and Interleukin17-Producing Th17 Cells Actively Influence HBV Clearance in De Novo Hepatitis B Virus Infected Patients after Orthotopic Liver Transplantation

Objective

To longitudinally investigate the role of FoxP3+ Regulatory T cells (Treg) and interleukin17-producing T helper 17 cells (Th17) in De Novo Hepatitis B Virus infection after orthotopic Liver Transplantation (DNHB-OLT), and analyze the possible correlation between these cells and HBV clearance of the disease.

Methods

We enrolled 12 control cases after orthotopic Liver Transplantation (OLT) and 24 patients, including 12 diagnosed with DNHB-OLT and 12 diagnosed with Acute Hepatitis B Virus infection (AHB), into the study from the liver transplantation and research center at Beijing 302 Hospital. Flow cytometry was used to detect the frequencies of Treg and Th17, and ELISA was applied to detect the concentration of IL6, IL22, TGF-β and IL2 in peripheral blood. We also measured the gene expression level by real time-quantitative PCR and protein expression using immunohistochemistry and western-blot. Furthermore, we divided DNHB-OLT patients into the clearance and non-clearance groups and examined longitudinally Th17, Treg cells at different times.

Results

The percentage of Treg cells, expression of FoxP3 mRNA and related anti-inflammatory cytokines such as IL2 and TGF-β1 in the DNHB-OLT group were significantly higher than that in the AHB and OLT groups. The percentage of Th17 cells, expression of RORγt mRNA and related pro-inflammatory cytokines such as IL17 and IL22 in the DNHB-OLT group were significantly lower than that in the AHB group, but the levels of these cytokines are very similar to the OLT group. The ratios of Treg to Th17 in the DNHB-OLT group were significantly higher than that in the OLT and AHB groups. Treg frequencies significantly correlated with HBV DNA, whereas IL17 frequencies didn’t significantly correlate with ALT. In DNHB-OLT patients, the clearance group was accompanied by a rapid increase in the Th17 cells during the first 4^th week and afterwards continuously decrease to the control group, together with a continuously decrease in Treg cells from the onset time point, which lead to a significant reduction in the ratios of Treg to Th17. The non-clearance group was accompanied by an increase in the Treg cells during the first 4^th week and afterwards sharply decrease, together with a relatively stable and unchanged Th17 cells, which lead to a significant change in the ratios. In addition, compared to clearance group, the ratios of Treg to Th17 in non-clearance group were significantly higher at the onset point, 4^th and 12^th week, but no difference at 24^th week.

Conclusion

DNHB-OLT patients possessed a favorable Treg differentiation environment, accompanied by a sustained higher preferentially Treg frequencies and up-regulation of related anti-inflammatory cytokines. The immune imbalance of the ratios between Treg and Th17 existed in DNHB-OLT patients. The changes of the ratios during the DNHB-OLT events were associated with HBV clearance, which suppressed immune inflammation reaction as well as inhibited ability of specific HBV clearance and led to immune escape and chronicity.

Testosterone Suppresses Hepatic Inflammation by the Downregulation of IL-17, CXCL-9, and CXCL-10 in a Mouse Model of Experimental Acute Cholangitis

Autoimmune liver diseases predominantly affect women. In this study, we aimed to elucidate how sex affects autoimmune hepatic inflammation. Acute experimental cholangitis was induced by adoptive transfer of OVA-specific CD8+ T cells into mice, which express the cognate Ag on cholangiocytes. In contrast to previous mouse models of cholangitis, this model displayed a strong sexual dimorphism: female mice developed marked cholangitis, whereas male mice were resistant to cholangitis induction. The recruitment of endogenous CD4+ T cells, but not transferred CD8+ T cells into female livers was strongly increased. These cells expressed higher amounts of the proinflammatory cytokine IL-17, which was at least in part responsible for the liver inflammation observed. The recruitment of endogenous CD4+ T cells was associated with increased expression of the chemokines CXCL-9 and CXCL-10 in female livers. The sex-specific factor responsible for the observed differences was found to be testosterone: male mice could be rendered susceptible to liver inflammation by castration, and testosterone treatment was sufficient to completely suppress liver inflammation in female mice. Accordingly, testosterone treatment of female mice significantly reduced the expression of IL-17A, CXCL-9, and CXCL-10 within the liver. Serum testosterone levels of untreated mice negatively correlated with the IL-17, CXCL-9, and CXCL-10 expression in the liver, further supporting a role for testosterone in hepatic immune homeostasis. In conclusion, testosterone was found to be the major determinant of the observed sexual dimorphism. Further study into the role of testosterone for liver inflammation could lead to novel treatment targets in human autoimmune liver diseases.

A prophylactic hepatitis C virus vaccine: a distant peak still worth climbing

Hepatitis C virus (HCV) infects an estimated more than 150 million people and is a leading cause of liver disease worldwide. The development of direct-acting antivirals (DAAs) will markedly improve the outcome of antiviral treatment with cure of the majority of treated patients. However, several hurdles remain before HCV infection can be considered a menace of the past: High treatment costs will most likely result in absent or limited access in middle and low resource countries and will lead to selective use even in wealthier countries. The limited efficacy of current HCV screening programs leads to a majority of cases being undiagnosed or diagnosed at a late stage and DAAs will not cure virus-induced end-stage liver disease such as hepatocellular carcinoma. Certain patient subgroups may not respond or not be eligible for DAA-based treatment strategies. Finally, reinfection remains possible, making control of HCV infection in people with ongoing infection risk difficult. The unmet medical needs justify continued efforts to develop an effective vaccine, protecting from chronic HCV infection as a mean to impact the epidemic on a global scale. Recent progress in the understanding of virus-host interactions provides new perspectives for vaccine development, but many critical questions remain unanswered. In this review, we focus on what is known about the immune correlates of HCV control, highlight key mechanisms of viral evasion that pose challenges for vaccine development and suggest areas of further investigation that could enable a rational approach to vaccine design. Within this context we also discuss insights from recent HCV vaccination studies and what they suggest about the best way to go forward.

Non-Hodgkin lymphoma and hepatitis C: where we are and what next?

The association between hepatitis C virus and certain B-cell non-Hodgkin lymphomas, such as marginal zone lymphomas, is supported by epidemiological studies. The exact pathogenetic mechanism is still unknown but both chronic antigenic stimulation and viral lymphotropism may contribute to the evolution of the malignant clone. Furthermore, the hematologic response following hepatitis C antiviral treatment suggests that the virus may have an etiologic role. Interferon and ribavirin based treatment proved to be successful in small case series of hepatitis C virus associated splenic lymphoma with villous lymphocytes, therefore, it is suggested that antiviral treatment could be an alternative to chemo-immunotherapy. In the near future new more potent direct acting antivirals will make interferon free treatments possible. It is still an open question whether these new short-course regimens are also effective in the treatment of associated lymphomas and what is the importance of the lymphoid reservoir in eliminating HCV.

Study of the impact of viral load of hepatitis C on patients with concomitant psoriasis vulgaris

BACKGROUND AND STUDY AIM

Concomitant hepatitis C virus (HCV) infection and psoriasis vulgaris (PV) are not uncommon coexisting diseases, especially in areas with high viral hepatitis endemicity. To date, data about the interaction between both diseases are scarce. Therefore, we aimed to describe the possible interplay between the HCV viral load and psoriatic activity in concomitant Egyptian diseased patients.

PATIENTS AND METHODS

Between December 2011 and August 2013, all psoriatic patients attending Assiut University Hospital outpatient clinics were tested for HCV serologic assay. Patients with positively coexisting diseases were further reevaluated for psoriasis area severity index (PASI) score assessment, liver function tests, HCV-RNA-polymerase chain reaction (PCR) assays, and sonographic examination of the liver. For comparative purposes, another matched group (n=26) with psoriasis only (HCV-negative group) was enrolled as a control.

RESULTS

During the period of the study, 20 patients with concomitant PV and HCV infection (HCV-positive group; 50% males, mean age of 44.15±10.66 years) were recruited. The mean PASI score was 44.75±10.38 and clinical signs of liver dysfunction were observed in 40% (n=8), 100% had abnormal liver function tests (n=20), and 75% had sonographic findings of cirrhosis (n=15). The PASI score was significantly higher in the HCV-positive psoriatic group compared to the HCV-negative control (p<0.001). Significant correlations were detected between the PASI score and the viral loads, and also with alanine aminotransferase (ALT).

CONCLUSION

When HCV was found concomitantly with PV, a high possibility of severe disease pattern will be expected that entails special precautions in the treatment process.

Th17 cells in autoimmune and infectious diseases

The view of CD4 T-cell-mediated immunity as a balance between distinct lineages of Th1 and Th2 cells has changed dramatically. Identification of the IL-17 family of cytokines and of the fact that IL-23 mediates the expansion of IL-17-producing T cells uncovered a new subset of Th cells designated Th17 cells, which have emerged as a third independent T-cell subset that may play an essential role in protection against certain extracellular pathogens. Moreover, Th17 cells have been extensively analyzed because of their strong association with inflammatory disorders and autoimmune diseases. Also, they appear to be critical for controlling these disorders. Similar to Th1 and Th2 cells, Th17 cells require specific cytokines and transcription factors for their differentiation. Th17 cells have been characterized as one of the major pathogenic Th cell populations underlying the development of many autoimmune diseases, and they are enhanced and stabilized by IL-23. The characteristics of Th17 cells, cytokines, and their sources, as well as their role in infectious and autoimmune diseases, are discussed in this review.

Chronic ethanol diet increases regulatory T-cell activity and inhibits hepatitis C virus core-specific cellular immune responses in mice

AIM

Chronic ethanol consumption is associated with persistent hepatitis C viral (HCV) infection. This study explores the role of the host cellular immune response to HCV core protein in a murine model and how chronic ethanol consumption alters T-cell regulatory (Treg) populations.

METHODS

BALB/c mice were fed an isocaloric control or ethanol liquid diet. Dendritic cells (DC) were isolated after expansion with a hFl3tL-expression plasmid and subsequently transfected with HCV core protein. Core-containing DC (1 × 10(6) ) were s.c. injected (×3) in mice every 2 weeks. Splenocytes from immunized mice were isolated and stimulated with HCV core protein to measure generation of viral antigen-specific Treg, as well as secretion of interleukin (IL)-2, tumor necrosis factor (TNF)-α and IL-4. Cytotoxicity was measured by lactate dehydrogenase release from HCV core-expressing syngeneic SP2/19 myeloma cells.

RESULTS

Splenocytes from mice immunized with ethanol-derived and HCV core-loaded DC exhibited significantly lower in vitro cytotoxicity compared to mice immunized with HCV core-loaded DC derived from isocaloric pair-fed controls. Stimulation with HCV core protein triggered higher IL-2, TNF-α and IL-4 release in splenocytes following immunization with core-loaded DC derived from controls as compared to chronic ethanol-fed mice. Splenocytes derived from mice immunized with core-loaded DC isolated from ethanol-fed mice exhibited a significantly higher CD25(+) FOXP3(+) and CD4(+) FOXP3(+) Treg population.

CONCLUSION

These results suggest that immunization with HCV core-containing DC from ethanol-fed mice induces an increase in the CD25(+) FOXP3(+) and CD4(+) FOXP3(+) Treg population and may suppress HCV core-specific CD4(+) and CD8(+) T-cell immune responses.

Regulatory role of CD4(+)CD25 (+)Foxp3 (+) regulatory T cells on IL-17-secreting T cells in chronic hepatitis B patients

BACKGROUND

Both interleukin (IL)-17-secreting CD4(+) T (Th17) and CD4(+)CD25(+)Foxp3(+) T regulatory (Treg) cells have been shown to be associated with disease progression or liver damage in chronic hepatitis B (CHB) patients. However, the relationship between Treg cells and IL-17-secreting T cells in hepatitis B virus (HBV) infections is unclear.

METHODS

The frequencies of Treg cells and IL-17-secreting T cells in hepatitis B e antigen (HBeAg)-positive CHB patients and healthy subjects were measured by flow cytometric analysis. The role of Treg cells on the differentiation of Ag-specific IL-17-secreting T cells was determined by removing the Treg cells from peripheral blood mononuclear cells (PBMCs) in HBeAg-positive CHB patients.

RESULTS

The frequencies of both Th17 (1.71 ± 0.58 vs. 1.08 ± 0.36 %; P < 0.01) and Treg cells (8.92 ± 4.11 vs. 6.45 ± 1.56 %; P < 0.01) were increased in the peripheral blood of HBeAg-positive CHB patients compared with healthy controls, but in not the IL-17-secreting CD8(+) T (Tc17) cells. The frequency of Treg cells was significantly associated with that of Th17 cells (r = 0.625, P = 0.001) in CHB patients. Spearman analysis showed a positive correlation between the frequency of Treg cells and HBV DNA load (r = 0.508, P = 0.008), as well as between the frequency of Th17 cells and serum alanine aminotransferase level (r = 0.516, P = 0.007). The deletion of Treg cells significantly enhanced both Th17 and Tc17 cell development in PBMCs following recombinant HBV core antigen stimulation.

CONCLUSIONS

Our data indicate a clear inverse relationship between Th17 cells and Treg cells and that Treg cells can inhibit Th17 cell development in CHB patients.

Protective immunity against hepatitis C: many shades of gray

The majority of individuals who become acutely infected with hepatitis C virus (HCV) develop chronic infection and suffer from progressive liver damage while approximately 25% are able to eliminate the virus spontaneously. Despite the recent introduction of new direct-acting antivirals, there is still no vaccine for HCV. As a result, new infections and reinfections will remain a problem in developing countries and among high risk populations like injection drug users who have limited access to treatment and who continue to be exposed to the virus. The outcome of acute HCV is determined by the interplay between the host genetics, the virus, and the virus-specific immune response. Studies in humans and chimpanzees have demonstrated the essential role of HCV-specific CD4 and CD8 T cell responses in protection against viral persistence. Recent data suggest that antibody responses play a more important role than what was previously thought. Individuals who spontaneously resolve acute HCV infection develop long-lived memory T cells and are less likely to become persistently infected upon reexposure. New studies examining high risk cohorts are identifying correlates of protection during real life exposures and reinfections. In this review, we discuss correlates of protective immunity during acute HCV and upon reexposure. We draw parallels between HCV and the current knowledge about protective memory in other models of chronic viral infections. Finally, we discuss some of the yet unresolved questions about key correlates of protection and their relevance for vaccine development against HCV.

Prevalence and clinical relevance of T-helper cells, Th17 and Th1, in hepatitis B virus-related hepatocellular carcinoma

Background and Aims

An immune imbalance in the cytokine profile exerts a profound influence on the progression of hepatitis B virus (HBV) infections and hepatocellular carcinoma (HCC). The present study evaluated the immune status of T helper (Th) 17 and Th1 cells in patients with HBV-related and non-HBV-related HCC.

Methods

We randomly enrolled 150 patients with HCC. Blood samples and tissue samples were obtained. The distributions and phenotypic features of Th17 and Th1 cells were determined by flow cytometry and/or immunohistochemistry.

Results

Compared to corresponding non-tumor regions, the levels of Th17 and Th1 cells were significantly increased in tumors of patients with HCC (P<0.001). The intratumoral densities of IL-17-producing cells and IFN-γ-producing cells were associated with overall survival (OS, P = 0.001) and disease-free survival (DFS, P = 0.001) of patients with HCC. The ratio of Th17 to Th1 in HBV-related HCC was higher than in non-HBV-related HCC. A multivariate Cox analysis revealed that the Th17 to Th1 ratio was an independent prognostic factor for OS (HR = 2.651, P = 0.007) and DFS (HR = 2.456, P = 0.002).

Conclusions

HBV infections can lead to an imbalance in immune status in patients with HCC. An elevated Th17 to Th1 ratio may promote tumor progression. The Th17 to Th1 ratio could serve as a potential prognostic marker for scoring the severity of HCC.

CD141⁺ myeloid dendritic cells are enriched in healthy human liver

BACKGROUND & AIMS

Extensive populations of liver immune cells detect and respond to homeostatic perturbation caused by damage, infection or malignancy. Dendritic cells (DCs) are central to these activities, governing the balance between tolerance and immunity. Most of our knowledge about human liver DCs is derived from studies on peritumoral tissue. Little is known about the phenotype and function of DCs, in particular the recently described CD141(+) subset, in healthy human liver and how this profile is altered in liver disease.

METHODS

During liver transplantation, healthy donor and diseased explant livers were perfused and hepatic mononuclear cells isolated. Dendritic cell subset frequency and phenotype were characterised in liver perfusates by flow cytometry and the function of CD141(+) DCs was evaluated by mixed lymphocyte reactions (MLRs) and measuring cytokine secretion.

RESULTS

Almost one third of liver CD11c(+) myeloid DCs (mDCs) expressed CD141 compared to <5% of circulating mDCs. Hepatic CD141(+) DCs demonstrated pro-inflammatory function in allogeneic MLRs, inducing T cell production of interferon gamma (IFN-γ) and interleukin (IL)-17. While CD123(+) plasmacytoid DCs (pDCs) and CD1c(+) mDCs were expanded in diseased liver perfusates, CD141(+) DCs were significantly depleted. Despite their depletion, CD141(+) DCs from explant livers produced markedly increased poly(I:C)-induced IFN lambda (IFN-λ) compared with donor DCs.

CONCLUSIONS

Accumulation of CD141(+) DCs in healthy liver, which are significantly depleted in liver disease, suggests differential involvement of mDC subsets in liver immunity.

Kinetics of Th17 cytokines during telbivudine therapy in patients with chronic hepatitis B

Th17 cells and the secreting cytokines play an important role in the immune response and inflammation that is induced by hepatitis B virus (HBV). However, it remains not fully elucidated how the antiviral agents affect Th17 cytokines and signal pathway. Telbivudine therapy has been proved to inhibit HBV replication effectively and to improve clinical outcome of chronic hepatitis B (CHB). Thus, in this study, the effect of decrease in viral load and liver dysfunction resulting from telbivudine treatment on Th17 cells and the related cytokines IL-17, IL-22, and IL-23 were analyzed. Peripheral blood mononuclear cells and serum from twenty-four CHB patients were harvested at 0, 12, 24, 36, and 48 weeks after initiation of telbivudine treatment. In parallel to the reduction of HBV DNA and normalization of serum ALT, significant declines in circulating HBV-specific Th17 cells and IL-22 production were found during antiviral therapy. The expression of serum IL-22 and IL-23, but not IL-17 also decreased during therapy. Our findings suggest that antiviral effect of telbivudine may attribute to both direct virus inhibition and regulation of inflammation, which further improve the understanding of pathogenesis of HBV infection and develop antiviral strategy for controlling viral hepatitis.

Dendritic cells and other innate determinants of T helper cell polarisation

Adaptive immunity plays a crucial role in natural host defence against pathogens and tumours, and is central to the long-term protective effect of vaccines. It is mediated by T and B cells that are activated through antigen-specific receptors. By contrast, innate immunity responds immediately to infection and damage, and is activated through binding of conserved pathogen or damage-associated molecules to pattern recognition receptors (PRRs) on dendritic cells (DCs) and other innate immunity cell types. Recent studies have demonstrated that the innate immune system also functions to direct the adaptive immune response, not only through antigen presentation but also by providing the key signals for the differentiation of naive CD4+ T cells into functionally distinct T helper (Th) cell subtypes.

Galectin-9 and IL-21 mediate cross-regulation between Th17 and Treg cells during acute hepatitis C

Loss of CD4 T cell help correlates with virus persistence during acute hepatitis C virus (HCV) infection, but the underlying mechanism(s) remain unknown. We developed a combined proliferation/intracellular cytokine staining assay to monitor expansion of HCV-specific CD4 T cells and helper cytokines expression patterns during acute infections with different outcomes. We demonstrate that acute resolving HCV is characterized by strong Th1/Th17 responses with specific expansion of IL-21-producing CD4 T cells and increased IL-21 levels in plasma. In contrast, viral persistence was associated with lower frequencies of IL-21-producing CD4 T cells, reduced proliferation and increased expression of the inhibitory receptors T cell immunoglobulin and mucin-domain-containing-molecule-3 (Tim-3), programmed death 1 (PD-1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4) on HCV-specific CD8 T cells. Progression to persistent infection was accompanied by increased plasma levels of the Tim-3 ligand Galectin-9 (Gal-9) and expansion of Gal-9 expressing regulatory T cells (Tregs). In vitro supplementation of Tim-3(high) HCV-specific CD8 T cells with IL-21 enhanced their proliferation and prevented Gal-9 induced apoptosis. siRNA-mediated knockdown of Gal-9 in Treg cells rescued IL-21 production by HCV-specific CD4 T cells. We propose that failure of CD4 T cell help during acute HCV is partially due to an imbalance between Th17 and Treg cells whereby exhaustion of both CD4 and CD8 T cells through the Tim-3/Gal-9 pathway may be limited by IL-21 producing Th17 cells or enhanced by Gal-9 producing Tregs.

Role of T cell immunity in hepatitis C virus infections

Chronic infections with the hepatitis C virus (HCV) are a major global health issue. Viral replication is restricted to hepatocytes, and occurs for decades at high replication rates. Over the last decade, it became accepted that HCV-specific CD4(+) and CD8(+) T cells are crucial for protective immunity to HCV. However, a characteristic feature of persistent HCV infection is the dysfunctional T cell response, and over recent years enormous progress has been made in understanding the mechanisms that dampen the antiviral T cell responses in blood and liver of chronic HCV patients and also impact disease progression.

Identifying early inflammatory changes in monocyte-derived macrophages from a population with IQ-discrepant episodic memory

Background

Cells of the innate immune system including monocytes and macrophages are the first line of defence against infections and are critical regulators of the inflammatory response. These cells express toll-like receptors (TLRs), innate immune receptors which govern tailored inflammatory gene expression patterns. Monocytes, which produce pro-inflammatory mediators, are readily recruited to the central nervous system (CNS) in neurodegenerative diseases.

Methods

This study explored the expression of receptors (CD11b, TLR2 and TLR4) on circulating monocyte-derived macrophages (MDMs) and peripheral blood mononuclear cells (PBMCs) isolated from healthy elderly adults who we classified as either IQ memory-consistent (high-performing, HP) or IQ memory-discrepant (low-performing, LP).

Results

The expression of CD11b, TLR4 and TLR2 was increased in MDMs from the LP group when compared to HP cohort. MDMs from both groups responded robustly to treatment with the TLR4 activator, lipopolysaccharide (LPS), in terms of cytokine production. Significantly, MDMs from the LP group displayed hypersensitivity to LPS exposure.

Interpretation

Overall these findings define differential receptor expression and cytokine profiles that occur in MDMs derived from a cohort of IQ memory-discrepant individuals. These changes are indicative of inflammation and may be involved in the prodromal processes leading to the development of neurodegenerative disease.

Hepatitis C virus targets the interferon-α JAK/STAT pathway by promoting proteasomal degradation in immune cells and hepatocytes

JAK/STAT signalling is essential for anti-viral immunity, making IFN-α an obvious anti-viral therapeutic. However, many HCV+ patients fail treatment, indicating that the virus blocks successful IFN-α signalling. We found that STAT1 and STAT3 proteins, key components of the IFN-α signalling pathway were reduced in immune cells and hepatocytes from HCV infected patients, and upon HCV expression in Huh7 hepatocytes. However, STAT1 and STAT3 mRNA levels were normal. Mechanistic analysis revealed that in the presence of HCV, STAT3 protein was preferentially ubiquitinated, and degradation was blocked by the proteasomal inhibitor MG132. These findings show that HCV inhibits IFN-α responses in a broad spectrum of cells via proteasomal degradation of JAK/STAT pathway components.

Hepatitis C virus promotes T-helper (Th)17 responses through thymic stromal lymphopoietin production by infected hepatocytes

Hepatitis C virus (HCV) is a major cause of liver cirrhosis and hepatocellular carcinoma. Here we report that infection of hepatic cells by HCV stimulates nuclear factor kappa B (NFκB)-dependent production of thymic stromal lymphopoietin (TSLP). Hepatocyte-derived TSLP in turn conditions dendritic cells (DCs) to drive T-helper (Th)17 differentiation. The TSLP secreted by HCV-infected hepatoma cells is capable of activating human monocyte-derived DCs by up-regulating the expression of CD40, CD86, CCL17, CCL22, and CCL20 which are activating markers of DCs. In addition, the production of key cytokines for Th17 differentiation, transforming growth factor beta (TGF-β), interleukin (IL)-6, and IL-21, is enhanced by human monocytes upon coculture with HCV-infected cells. Importantly, the blockade of TSLP using neutralizing antibody prevented the activation and maturation of DCs as well as the production of Th17 differentiation cytokines. DC conditioning by TSLP secreted from HCV-infected cells activated naïve CD4+ T lymphocytes, resulting in Th17 differentiation. Furthermore, we can detect substantial levels of hepatocyte TSLP in fibrotic liver tissue from chronic HCV patients. Thus, blockade of TSLP released by HCV-infected hepatocytes may suppress the induction/maintenance of hepatic Th17 responses and halt the progression of chronic liver disease to fibrosis and liver failure.

CONCLUSION

Hepatocyte-derived TSLP conditions DCs to drive Th17 differentiation. Treatment of TSLP neutralizing antibody in HCV-infected hepatocyte/DC coculture abrogates DC conditioning and thereby inhibits Th17 differentiation.

Imbalance of interleukin-17-producing CD4 T cells/regulatory T cells axis occurs in remission stage of patients with hepatitis B virus-related acute-on-chronic liver failure

BACKGROUND AND AIM

Although regulatory T cells (Treg) and interleukin-17-producing CD4 T cells (Th17) have been demonstrated to play opposing roles in inflammation-associated diseases, their frequency and balance in different stages of hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF) remain unknown.

METHODS

Fourteen patients with HBV-associated ACLF were studied and defined into different stages according to disease activity. Circulating Th17 cells and Treg cells were analyzed by flow cytometry, and the cytokines were quantitated by enzyme-linked immunosorbent assay. Results were correlated with temporal changes in viral load, disease progression and compared with 30 chronic hepatitis B (CHB) subjects and 18 healthy subjects.

RESULTS

We showed a significantly higher frequency of circulating Th17 cells in the remission stage of ACLF when compared with the progression stage, the CHB group, or normal controls. However, the frequency of circulating Treg cells was significantly lower in the remission stage of ACLF when compared with the progression stage or the CHB group. The increase in Th17 cells and concomitant decrease in Treg cells created an imbalance in the remission stage of ACLF patients, which negatively correlated with disease progression. In addition, we showed that ACLF patients in the remission stage had an altered profile of cytokines that regulated the induction of Th17 cells and Treg cells.

CONCLUSIONS

ACLF patients in the remission stage had an imbalance of Th17 to Treg cells, which could be used as a prognostic marker to predict disease progression. This imbalance could play a role in the immunopathogenesis of HBV-related ACLF.