Imbalance of regulatory T cells and T helper type 17 cells in patients with chronic hepatitis C

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.

Hepatitis B and C among patients with hidradenitis suppurativa: a population-based study

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic inflammatory condition related to multiple systemic diseases and infections.

METHODS

This retrospective cross-sectional study from 1999 to 2015 used the database of Clalit Health Services, the largest managed care organization in Israel, to explore the association between HS and hepatitis B and C. Sociodemographic and clinical information was compared using χ² tests for sex and socioeconomic status and t-tests for age. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) to compare the odds of hepatitis B and C in those with and without HS.

RESULTS

In multivariate analysis controlling for sex, age as a continuous variable, Arab ancestry, and history of drug abuse, HS was associated with a 1.87-fold increased odds (95% CI 1.11-3.17, P = 0.019) of hepatitis B (HBV). HS was also associated with HCV in multivariate analysis controlling for sex, age per year, Arab ancestry, alcohol use, and drug use, with a 1.74-fold increased odds (95% CI 1.05-2.89, P = 0.032) of hepatitis C (HCV) among those with HS as compared to controls.

CONCLUSIONS

This study demonstrated an association between HS and both hepatitis B and hepatitis C.

Chronic Hepatitis C Virus Infection Modulates the Transcriptional Profiles of CD4+ T Cells

Background

Chronic hepatitis C (CHC) is associated with altered cell-mediated immune response.

Objective

The aim of the study was to characterize functional alterations in CD4⁺ T cell subsets and myeloid-derived suppressor cells (MDSCs) during chronic hepatitis C virus (HCV) infection. Methodology. The expression levels of the lineage-defining transcriptional factors (TFs) T-bet, Gata3, Rorγt, and Foxp3 in circulating CD4⁺ T cells and percentages of MDSCs in peripheral blood were evaluated in 33 patients with CHC, 31 persons, who had spontaneously cleared the HCV infection, and 30 healthy subjects. Analysis. The CD4+ T cells TFs T-bet (T-box expressed in T cells), Foxp3 (Forkhead box P3 transcription factor), Gata3 (Gata-binding protein 3), and Rorγt (retinoic-acid-related orphan receptor gamma) and activation of CD8+ T cells, as well as percentages of MDSCs, were measured by multicolor flow cytometry after intracellular and surface staining of peripheral blood mononuclear cells with fluorescent monoclonal antibodies.

Result

The patients with CHC had significantly lower percentages of CD4⁺ T cells expressing Rorγt and Gata3 and higher percentages of Foxp3-expressing CD4⁺ T cells than healthy controls and persons who spontaneously cleared HCV infection. The ratios of T-bet⁺/Gata3⁺ and Foxp3⁺/Rorγt⁺ CD4⁺ T cells were the highest in the patients with CHC. In the patients with CHC, the percentages of Gata3⁺ and Rorγt⁺ CD4⁺ T cells and the percentages of T-bet⁺ CD4⁺ T cells and CD38⁺/HLA-DR⁺ CD8⁺ T cells demonstrated significant positive correlations. In addition, the percentage of CD38⁺/HLA-DR⁺ CD8⁺ T cells correlated negatively with the percentage of MDSCs.

Conclusion

Chronic HCV infection is associated with downregulation of TFs Gata3 and Rorγt polarizing CD4+ T cells into Th2 and Th17 phenotypes together with upregulation of Foxp3 responsible for induction of regulatory T cells suppressing immune response.

Strategies Targeting the Innate Immune Response for the Treatment of Hepatitis C Virus-Associated Liver Fibrosis

Direct-acting antivirals eliminate hepatitis C virus (HCV) in more than 95% of treated individuals and may abolish liver injury, arrest fibrogenesis, and reverse fibrosis and cirrhosis. However, liver regeneration is usually a slow process that is less effective in the late stages of fibrosis. What is more, fibrogenesis may prevail in patients with advanced cirrhosis, where it can progress to liver failure and hepatocellular carcinoma. Therefore, the development of antifibrotic drugs that halt and reverse fibrosis progression is urgently needed. Fibrosis occurs due to the repair process of damaged hepatic tissue, which eventually leads to scarring. The innate immune response against HCV is essential in the initiation and progression of liver fibrosis. HCV-infected hepatocytes and liver macrophages secrete proinflammatory cytokines and chemokines that promote the activation and differentiation of hepatic stellate cells (HSCs) to myofibroblasts that produce extracellular matrix (ECM) components. Prolonged ECM production by myofibroblasts due to chronic inflammation is essential to the development of fibrosis. While no antifibrotic therapy is approved to date, several drugs are being tested in phase 2 and phase 3 trials with promising results. This review discusses current state-of-the-art knowledge on treatments targeting the innate immune system to revert chronic hepatitis C-associated liver fibrosis. Agents that cause liver damage may vary (alcohol, virus infection, etc.), but fibrosis progression shows common patterns among them, including chronic inflammation and immune dysregulation, hepatocyte injury, HSC activation, and excessive ECM deposition. Therefore, mechanisms underlying these processes are promising targets for general antifibrotic therapies.

The role of Th17 cells in viral infections

The present review provides an overview of recent advances regarding the function of Th17 cells and their produced cytokines in the progression of viral diseases. Viral infections alone do not lead to virus-induced malignancies, as both genetic and host safety factors are also involved in the occurrence of malignancies. Acquired immune responses, through the differentiation of Th17 cells, form the novel components of the Th17 cell pathway when reacting with viral infections all the way from the beginning to its final stages. As a result, instead of inducing the right immune responses, these events lead to the suppression of the immune system. In fact, the responses from Th17 cells during persistent viral infections causes chronic inflammation through the production of IL-17 and other cytokines which provide a favorable environment for tumor growth and its development. Additionally, during the past decade, these cells have been understood to be involved in tumor progression and metastasis. However, further research is required to understand Th17 cells' immune mechanisms in the vast variety of viral diseases. This review aims to determine the roles and effects of the immune system, especially Th17 cells, in the progression of viral diseases; which can be highly beneficial for the diagnosis and treatment of these infections.

Modulation of Immune Cell Subsets by Hepatitis C Virus and Antiviral Therapy in Early Virological Response HCV Genotype 4-Infected Patients with Compensated Liver Disease

BACKGROUND

Resolution of chronic hepatitis C virus (HCV) infection requires a complicated interaction between immune cell subsets. The effect of antiviral therapy on immune cell subsets remains to be defined. This study aimed to investigate the absolute count of certain immune cell subsets during therapy with pegylated interferon-α and ribavirin (PegIFN/RBV).

MATERIALS AND METHODS

Sixty HCV genotype 4-infected patients with compensated liver disease were treated with PegIFN/RBV therapy for 52 weeks. Efficacy was measured by studying the early virological response (EVR) at post-therapy week 12. Absolute counts of mature T cells, T helper cells, T cytotoxic cells, activated T cells, natural killer cells, natural killer/T (NKT) cells, B cells, and T regulatory cells (Treg), and the ratio of T helper to T cytotoxic cells were longitudinally analyzed by flow cytometry throughout the treatment and follow-up course.

RESULTS

Of the 60 genotype 4-infected subjects, 39 (65%) had EVR and 21 (35%) were non-EVR patients. In the first part of this study, there were significantly lower mean absolute count values of mature T, T cytotoxic, B, and NKT cells. Also, we detected statistically significantly lower mean values for the percentages of T cytotoxic, NKT, Treg, and activated T cells of HCV-infected patients at baseline values when compared with healthy subjects. After the initiation of PegIFN/RBV therapy, frequencies of T helper cells, activated T cells, Treg cells, B cells, and T helper:T cytotoxic ratio were found to be significantly lower in EVR patients than in non-EVR patients (p < 0.05). In contrast, frequencies of T cytotoxic and NKT cells were significantly increased in EVR patients when compared to non-EVR patients (p < 0.05).

CONCLUSION

These results suggest a pattern of higher levels of T cytotoxic and NKT cells, and lower levels of T helper, activated T, Treg, and B cell populations in patients who respond favorably to PegIFN/RBV therapy.

Serum Interleukin-35 Level in Correlation with T Regulatory and T helper-17 Cells Frequency in Chronic Viral Hepatitis C Patients

Interleukin-35 (IL-35), secreted mainly by T-regulatory cells (T-regs), has been considered to have immunosuppressive actions in many auto-immune diseases and tumors. However, information about its role in chronic hepatitis C (CHC) infection is still limited. We aimed to study the role of IL-35 within CHC infection and to assess its correlation with T-regs and T-helper 17 cells (Th-17). Therefore, we measured serum IL-35 concentrations using ELISA assay in 25 normal controls (NCs) and in 30 CHC patients before receiving direct antiviral agents (DAA) treatment and after 3 months of treatment end. T-regs and Th-17 cells frequencies were assessed via flow-cytometry in control group and patients’ group before treatment. The results showed that serum IL-35 levels revealed a highly significant increase in CHC patients compared to NCs (P <0.001). Moreover, IL-35 levels significantly decreased in patients 3 months after treatment end (P =0.02). Both Th-17 and T-regs were significantly increased in patients more than in NCs and a positive correlation was observed between them. However, T-regs/Th-17 ratio did not show significant difference from the ratio in NCs. IL-35 levels were positively correlated with viral load and T-regs frequency, but not with Th-17 frequency. IL-35 levels did not correlate with liver enzymes or functions. These results suggested that IL-35 enhances the immunosuppressive functions of T-regs, protecting the liver from HCV induced damage and contributes to viral persistence. IL-35 may represent a possible immunotherapeutic strategy for chronic persistent infection if given with DAA, especially in relapsing or non-responding cases.

The Binary Classification Of Chronic Diseases

Acute diseases start with an insult and end when insult disappears. If the trauma induces an immune reaction (which happens in most cases), this reaction must be terminated with some type of resolution mechanism, when the cause of the trauma ceases. Chronicity develops if insult is permanent or if the resolution mechanism is defective. Another way to reach disease chronicity is a positive feedback loop, whereby the immune reaction activates an internal, insult-like reaction. A distinction between chronic states characterized by a persistent, low suppressive effect and those characterized by a persistent, high suppressive effect of regulatory T cells (Treg), is proposed. This two-class division represents two ways to reach chronicity: (a) by maintaining inflammatory reaction long after insult disappears ("low Treg"), or (b) by suppressing inflammatory reaction prior to the disappearance of insult ("high Treg"). This two-class division may explain the strong association between certain pathogens and cancer, on one hand, and between several other pathogens and autoimmunity, on the other hand. The weak association between autoimmune diseases and HIV infection and the relatively weak association between autoimmune diseases and cancer may be elucidated as well. In addition, the model rationalizes why immune-modulating drugs, which are effective in cancer, are also effective in "high Treg" viral infections, while corticosteroids, which are generally effective in autoimmune diseases, are also effective in other "low Treg" diseases (such as asthma, atopic dermatitis, and "low Treg" infections) but are not effective in solid malignancies and "high Treg" infections. Moreover, the model expounds why certain bacteria inhibit tumor growth and why these very bacteria induce autoimmune diseases.

Interleukin-37 Inhibits the Imbalance Between T Helper 17 Cells and Regulatory T Cells in Hand, Foot, and Mouth Disease

The aim of this study was to explore the role of interleukin-37 (IL-37) in imbalance of T helper (Th)17/regulatory T cells (Tregs) in hand, foot, and mouth disease (HFMD). The proportions of CD4⁺ IL-17A⁺ Th17 cells and CD4⁺ CD25⁺Foxp3⁺ Tregs in peripheral blood or peripheral blood mononuclear cells (PBMCs) from HFMD patients and healthy controls were measured by fluorescence activated cell sorter. The level of IL-37, IL-10, IL-17A, IL-23, and transforming growth factor β1 (TGF-β1) in serum or PBMCs of HFMD patients and control subjects were detected using enzyme-linked immunosorbent assay. Results showed that Th17 cells proportion and IL-17A and IL-23 levels were highly increased, whereas Tregs proportion and IL-10 and TGF-β1 levels were significantly decreased in HFMD patients. Moreover, IL-37 stimulation elevated Tregs proportion but reduced Th17 cell proportion in subjects with HFMD. On the contrary, we found methylprednisolone pulse therapy/methylprednisolone combinated with intravenous gamma globulin inhibits Th17/Treg imbalance through upregulation of IL-37 in HFMD. In conclusion, IL-37 inhibits the imbalance of Th17/Tregs in HFMD.

Impact of direct-acting antiviral agents on the development of hepatocellular carcinoma: evidence and pathophysiological issues

Hepatitis C virus (HCV) infection is currently one of the main causes of cirrhosis and hepatocellular carcinoma (HCC) at a global level. Recently, a new generation of direct-acting antiviral agents (DAAs) has entered the HCV treatment landscape, providing impressively high rates of sustained virological response (SVR), and is expected to lead to an eventual decrease in HCV-related cirrhosis, liver transplantation and mortality. However, during the first years of their use, several studies reported a possible correlation between DAA treatment and an increased risk of HCC. Following the publication of larger prospective studies, the risk of de novo HCC occurrence has clearly been proven to be lower after the achievement of SVR, regardless of antiviral treatment. On the other hand, the risk of HCC recurrence following treatment with DAAs is debatable; existing data remain controversial, possibly because of the lack of large, well designed cohorts with more homogeneous patient populations. With regard to the pathophysiology behind the above observations, especially in patients with previous HCC history, HCC development could possibly be favored by the changes in the immunological milieu and the different cellular behavior after eradication of HCV infection with DAA treatment.

Decreased CD4+CD25+CD127dim/- Regulatory T Cells and T Helper 17 Cell Responsiveness to Toll-Like Receptor 2 in Chronic Hepatitis C Patients with Daclatasvir Plus Asunaprevir Therapy

Direct-acting antivirals (DAAs) not only rapidly inhibited hepatitis C virus (HCV) replication but also modulated innate and adaptive immune response in chronic hepatitis C patients. However, the regulatory activity of DAAs to Toll-like receptor 2 (TLR2) stimulation on CD4⁺CD25⁺CD127^dim/- regulatory T cells (Tregs) and T helper (Th) 17 cells was not completely understood. In the present study, a total of 23 patients with chronic HCV genotype 1b infection were enrolled, and blood samples were collected at baseline (treatment naive), end of therapy (EOT), and 12 weeks after EOT (SVR12) with daclatasvir plus asunaprevir therapy. TLR2 expression on Tregs and Th17 cells was measured by flow cytometry. Cellular proliferation, cytokine production, and suppressive activity were also tested in purified CD4⁺CD25⁺CD127^dim/- Tregs in response to the stimulation of Pam3Csk4, an agonist of TLR2. Inhibition of HCV RNA by daclatasvir and asunaprevir did not affect either percentage of Tregs/Th17 cells or TLR2 expression on Tregs/Th17 cells. Pam3Csk4 stimulation also did not influence either cellular proliferation or Tregs/Th17 proportion at each time point. Stimulation with Pam3Csk4 only enhanced the suppressive function and interleukin (IL)-35 production by Tregs purified from baseline, but not those from EOT or SVR12. Similarly, Pam3Csk4 stimulation only elevated Th17 cell frequency of CD4⁺ T cells from baseline, but not those from EOT or SVR12. Moreover, daclatasvir and asunaprevir therapy did not promote TLR2-induced shift of Tregs toward Th17-like phenotype and function. These data suggested that daclatasvir plus asunaprevir therapy resulted in the decreased responsiveness of Tregs/Th17 cells to TLR2 stimulation in chronic hepatitis C patients, which might provide a novel mechanism underlying DAA-induced immunoregulation.

Interleukin-35 Modulates the Imbalance Between Regulatory T Cells and T Helper 17 Cells in Enterovirus 71-Induced Hand, Foot, and Mouth Disease

Interleukin (IL)-35 modulates the imbalance between regulatory T cells (Tregs) and T helper (Th) 17 cells, which played vital roles in the pathogenesis of autoimmune and infectious diseases. However, the role of Tregs/Th17 cell imbalance and the regulatory functions of IL-35 have remained largely unknown in enterovirus 71 (EV71)-induced hand, foot, and mouth disease (HFMD). In this study, a total of 47 HFMD patients (30 with mild HFMD and 17 with severe HFMD) and 13 healthy individuals were enrolled. The frequencies of CD4⁺CD25⁺CD127^dim/- Tregs and CD4⁺IL-17⁺ Th17 cells, as well as IL-35 expression levels, were measured. Cellular proliferation and cytokine production was also determined in purified Tregs following recombinant IL-35 stimulation. An imbalance between Tregs and Th17 cells was observed in children with severe HFMD, which manifested as a reduction in the Tregs population and an elevation in the Th17 population. Serum IL-35 concentrations were also decreased in case of severe HFMD, which correlated with the Tregs:Th17 cell ratios. Recombinant IL-35 stimulation increased the proportion of Tregs, but downregulated that of Th17 cells. Treatment with IL-35 enhanced Tregs suppressive function and IL-35 and IL-10 expression, but reduced IL-22 secretion in both healthy individuals and those with severe HFMD. The Tregs:Th17 cell ratio was increased in the convalescent patients, however, a significant reduction in serum IL-35 was not observed. Our findings indicated that EV71 infection shifted the Tregs:Th17 cell ratio through IL-35 by downregulating inhibitory cytokine production and reducing the cell-to-cell contact inhibition of effector T cells. Regulation of IL-35 as it relates to the Tregs/Th17 balance may play a critical role in the pathogenesis of EV71-associated HFMD.

Chronic hepatitis C liver microenvironment: role of the Th17/Treg interplay related to fibrogenesis

The role of the different lymphocyte populations in liver microenvironment of chronic hepatitis C (CHC) patients is still matter of debate. Since Th17 and Treg have opposite functions, their balance could affect disease progression. The aim was to explore liver microenvironment and its peripheral blood counterpart in adult CHC patients. CD4⁺ lymphocytes were predominant in the liver, with high Foxp3⁺ but low IL-17A⁺ frequency. IL-17A⁺ lymphocytes and IL-17A⁺/Foxp3⁺ ratio displayed association with advanced fibrosis (p = 0.0130; p = 0.0236, respectively), while Foxp3⁺ lymphocytes and IL-10 expression level inversely correlated with fibrosis severity (p = 0.0381, p = 0.0398, respectively). TGF-β/IL-6 ratio correlated with IL-17A⁺/Foxp3⁺ ratio (p = 0.0036, r = 0.5944) and with IL-17A⁺ lymphocytes (p = 0.0093; r = 0.5203). TNF-α and TGF-β were associated with hepatitis severity (p = 0.0409, p = 0.0321). Peripheral blood lymphocyte frequency was not associated with liver damage. There are functionally different immune cell populations actively involved in liver damage, but the liver cytokine milieu actually drives the pathogenesis. The intrahepatic Foxp3⁺ lymphocytes predominance beside the low IL-17A⁺ lymphocytes frequency, delineate a skewed IL-17A⁺/Foxp3⁺ balance towards Foxp3⁺ lymphocytes. However, the IL-17A⁺ lymphocytes association with advanced fibrosis denotes their role in the pathogenesis. Therefore, the interplay between Th17 and Treg conditions liver fibrogenesis.

A Study of the Changes of T Helper 17 Cells and Regulatory T Cells in Herpes Zoster

BACKGROUND

Immunosuppression and age-related deficiencies in cell-mediated immunity are important factors for the reactivation of latent varicella-zoster virus (VZV). CD4⁺CD25⁺Foxp3⁺ regulatory T (Treg) cells and T helper 17 (Th17) cells are closely associated with various viral infections.

OBJECTIVE

We analyzed Treg cells and Th17 cells in patients with herpes zoster and investigated their relationship with the reactivation of latent VZV.

METHODS

Treg and Th17 cells in peripheral blood and the ratio of Th17 to Treg cells were examined in patients with herpes zoster and healthy controls. Changes between pre-treatment and post-treatment estimates of Treg and Th17 cells and clinical parameters in patients with herpes zoster were also analyzed.

RESULTS

The proportion of circulating Th17 cells and the Th17/Treg cell ratio were significantly higher in patients with herpes zoster than controls (p=0.012, 0.013), but there was no significant difference in the proportion of Treg cells between groups. There was no significant difference in the proportions of Treg and Th17 cells and the Th17/Treg cell ratio before and after treatment and between the non-postherpetic neuralgia and postherpetic neuralgia groups. Changes in Treg and Th17 cells and the Th17/Treg cell ratio were not significantly correlated with changes in the visual analog scale. Body surface area was significantly correlated with Treg cells, Th17 cells, and the Th17/Treg cell ratio (p=0.022, 0.002, 0.004).

CONCLUSION

An imbalance between Th17 and Treg cells is associated with the reactivation of VZV, which may contribute to pathogenesis of herpes zoster.

Immunological dynamics associated with rapid virological response during the early phase of type I interferon therapy in patients with chronic hepatitis C

Type I interferons (IFNs) play an important role in antiviral immunity as well as immunopathogenesis of diverse chronic viral infections. However, the precise mechanisms regulating the multifaceted effects of type I IFNs on the immune system and pathological inflammation still remain unclear. In order to assess the immunological dynamics associated with rapid viral clearance in chronic hepatitis C patients during the acute phase of type I IFN therapy, we analyzed multiple parameters of virological and immunological responses in a cohort of 59 Korean hepatitis C patients who received pegylated IFN-α and ribavirin (IFN/RBV). Most of the Korean patients had favorable alleles in the IFN-λ loci for responsiveness to IFN/RBV (i.e., C/C in rs12979860, T/T in rs8099917, and TT/TT in rs368234815). Rapid virological response (RVR) was determined mainly by the hepatitis C virus genotype. Among the cytokines analyzed, higher plasma levels of IL-17A and FGF were observed in non-RVR patients infected with viral genotype 1 and IP-10 was consistently elevated in RVR group infected with genotype 2 during the early phase of antiviral therapy. In addition, these three cytokines were correlated each other, suggesting a functional linkage of the cytokines in antiviral responses during IFN/RBV therapy. A low baseline frequencies of regulatory T cells and γδ T cells, but high level of group 2 innate lymphoid cells, in peripheral bloods were also significantly associated with the RVR group, implicating a potential role of the cellular immunity during the early phase of IFN/RBV therapy. Therefore, the immunological programs established by chronic hepatitis C and rapid disruption of the delicate balance by exogenous type I IFN might be associated with the subsequent virological outcomes in chronic hepatitis C patients.

Interferon lambda polymorphisms associate with body iron indices and hepatic expression of interferon-responsive long non-coding RNA in chronic hepatitis C

Single nucleotide polymorphisms (SNPs) within DNA region containing interferon lambda 3 (IFNL3) and IFNL4 genes are prognostic factors of treatment response in chronic hepatitis C (CHC). Iron overload, frequently diagnosed in CHC, is associated with unfavorable disease course and a risk of carcinogenesis. Its etiology and relationship with the immune response in CHC are not fully explained. Our aim was to determine whether IFNL polymorphisms in CHC patients associate with body iron indices, and whether they are linked with hepatic expression of genes involved in iron homeostasis and IFN signaling. For 192 CHC patients, four SNPs within IFNL3-IFNL4 region (rs12979860, rs368234815, rs8099917, rs12980275) were genotyped. In 185 liver biopsies, histopathological analyses were performed. Expression of five mRNAs and three long non-coding RNAs (lncRNAs) was determined with qRT-PCR in 105 liver samples. Rs12979860 TT or rs8099917 GG genotypes as well as markers of serum and hepatocyte iron overload associated with higher activity of gamma-glutamyl transpeptidase and liver steatosis. The presence of two minor alleles in any of the tested SNPs predisposed to abnormally high serum iron concentration and correlated with higher hepatic expression of lncRNA NRIR. On the other hand, homozygosity in any major allele associated with higher viral load. Patients bearing rs12979860 CC genotype had lower hepatic expression of hepcidin (HAMP; P = 0.03). HAMP mRNA level positively correlated with serum iron indices and degree of hepatocyte iron deposits. IFNL polymorphisms influence regulatory pathways of cellular response to IFN and affect body iron balance in chronic hepatitis C virus infection.

The proportion of different interleukin-17-producing T-cell subsets is associated with liver fibrosis in chronic hepatitis C

Studies have suggested the pivotal role of T helper type 1 (Th1) -related cytokines on the outcome of hepatitis C virus (HCV) infection. Nevertheless, the role of different interleukin-17 (IL-17) -secreting T cells on chronic hepatitis C (CHC) is less clear. Here, the in vivo IL-1β, IL-6, and IL-17 levels were positively correlated with both alanine transaminase (ALT) levels and hepatic lesions. When compared with the control group, CHC patients showed a lower proportion of IL-17-secreting (CD4⁺ and CD8⁺ ) T cells capable of simultaneously producing IL-21. Moreover, the percentage of IL-10-secreting Th17 cells was also lower in CHC patients. Notably, advanced liver lesions were observed among those patients with lower percentage levels of IL-17-producing T cells positive for IL-21, interferon-γ (IFN-γ) and IL-10. In contrast, the severity of hepatic damage was associated with peripheral single IL-17⁺ T cells. The percentage of IL-17⁺ IL-21^- IFN-γ⁺ (CD4⁺ and CD8⁺ ) T-cell phenotypes was positively associated with plasma CD14 levels. Finally, elevated levels of circulating CD14 were detected among CHC patients with extensive liver damage. In summary, although preliminary, our results suggest that a balance between different IL-17-producing T cells, associated with peripheral levels of CD14, may be a progress marker for liver disease in chronically HCV-infected patients.

Decrease in regulatory T-cell function in chronic hepatitis C patients receiving pegylated-interferon plus ribavirin

OBJECTIVES

Regulatory T-cells (Tregs) play an important role in the pathogenesis of chronic hepatitis C (CHC) infection. Pegylated interferon is the standard therapy for CHC patients in Asian countries. This study aimed to evaluate the frequency and function of Tregs in CHC patients receiving combination therapy.

METHODS

CHC patients (n=30) who had elevated alanine aminotransferase and underwent combination therapy were included. Clinical data and Treg function were checked at baseline, 12 weeks after treatment, at the end of treatment, and at the end of 24 weeks of follow-up. Treg immunosuppressive activity was measured as the inhibition ratio of conventional T-cell proliferation.

RESULTS

Treg-mediated immunosuppression was significantly lower during therapy than at baseline (baseline 44.45%; 12 weeks 18.41% (p=0.042); end of treatment 22.62% (p=0.036); end of follow-up 17.46% (p=0.003)). Treg-mediated immunosuppression was higher in patients with a sustained virological response (SVR) than in those without SVR at the end of follow-up (SVR 24.20%, non-SVR 6.87%; p=0.030).

CONCLUSION

Treg-mediated immunosuppression was lower during and after combination therapy, regardless of the treatment response, and higher in patients with SVR than in those without SVR at the end of follow-up.

Notch Signaling Modulates the Balance of Regulatory T Cells and T Helper 17 Cells in Patients with Chronic Hepatitis C

The imbalance of regulatory T cells (Tregs) and T helper 17 (Th17) cells contributes to the persistent hepatitis C virus (HCV) infection. However, modulatory factors associated with Tregs-Th17 balance were not fully elucidated. A recent study demonstrated an immunoregulatory strategy by inactivation of Notch signaling to reverse the disequilibrium of Tregs-Th17 cells in immune thrombocytopenia. Thus, the aim of this study was to assess the effect of Notch signaling in regulating the functions of Tregs and Th17 cells in chronic hepatitis C. A total of 46 patients with chronic hepatitis C and 17 normal controls (NCs) were enrolled. mRNA expressions of Notch1 and Notch2 were semiquantified by real-time reserve polymerase chain reaction. Percentages of Tregs-Th17, levels of key transcriptional factors, and cytokine productions were measured in response to treatment by DAPT, a γ-secretase inhibitor to suppress Notch signaling. We found that Notch1 and Notch2 mRNAs were significantly elevated in peripheral blood mononuclear cells from chronic hepatitis C patients compared with those from NCs. DAPT treatment reduced Th17 response by downregulation of RORγt expression and interleukin (IL)-17/IL-22 secretion. Tregs proportion, FoxP3 expression, and IL-10 production did not change significantly with DAPT treatment in chronic hepatitis C; however, blockage of Notch signaling inhibited the suppressive function of Tregs. Moreover, effective anti-HCV therapy not only reduced Notch1 and Notch2 expression but also decreased Tregs and Th17 proportions. The current data provided a novel mechanism underlying the modulation of Treg-Th17 balance. The link between Notch signaling and Th cells might lead to a new intervention for breaking immunotolerance of chronic HCV infection.

Involvement of the Interleukin-23/Interleukin-17 Axis in Chronic Hepatitis C Virus Infection and Its Treatment Responses

Interleukin-23 (IL-23) and its downstream factor IL-17 are the key cytokines involved in immune and inflammatory response in chronic liver diseases. This study aimed to investigate the role and molecular mechanisms of the IL-23/Th17 axis in chronic hepatitis C virus (HCV) infection, and the efficacy of IL-23/Th17 modulation in response to anti-HCV therapy. Sixty-six HCV-infected patients and 20 healthy controls were enrolled. The patients received PegIFNa-2a and ribavirin therapy for at least 48 weeks. The plasma level of IL-23 and the number of IL-17A-, IFN-γ-, and IL-21-producing peripheral blood mononuclear cells (PBMCs) at baseline and 12, 24, and 48 weeks following treatment were determined. The mRNA level of Th17 immune-associated molecules in PBMCs was evaluated by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) following treatment with IL-23 agonist or antagonist. Our data showed that, compared to healthy controls, HCV-infected patients had an increased plasma level of IL-23 and increased frequencies of IL-17A- and IFN-γ-producing PBMCs, whereas the HCV patients exhibited a reduced number of IL-21-producing PBMCs. However, the baseline frequencies of IL-21-producing PBMCs were markedly higher in HCV patients who achieved rapid virological response (RVR) than those without RVR. Additionally, the mRNA expressions of IL-21, IFN-γ, myxovirus resistance protein A (MxA), and suppressor of cytokine signaling 3 (SOCS3) were significantly upregulated in PBMCs, while FoxP3 expression was suppressed by IL-23 agonist. Thus, the IL-23/Th17 axis plays an important role in development of chronic HCV infection and antiviral response. IL-23 may enhance the antiviral activity of interferon-based therapy by modulating the expression of Th17 cells-associated molecules in HCV-infected patients.

Toll-Like Receptor 2 Modulates the Balance of Regulatory T Cells and T Helper 17 Cells in Chronic Hepatitis C

Regulatory T cells (Tregs) and interleukin-17-producing T helper (Th17) cells were mutually antagonistic in the pathogenesis of chronic hepatitis C virus (HCV) infection. However, the regulation of imbalance between Tregs and Th17 cells was poorly understood in HCV infection. A recent report revealed the immunomodulatory role of Toll-like receptor (TLR) 2 in regulating the balance of Tregs/Th17 functions in multiple sclerosis. Thus, the aim of the current study was to assess the effect of TLR2 stimulation on the suppressive function of Tregs and Th17 differentiation in chronic hepatitis C. A total of 65 patients with chronic hepatitis C receiving pegylated interferon-a2a and ribavirin therapy for 48 weeks, as well as 20 of normal controls (NCs) were enrolled. Cellular proliferation and cytokine production was tested in purified CD4(+)CD25(+)CD127(dim/-) Tregs in response to the stimulation of Pam3Csk4, an agonist of TLR2. In treatment-naive patients, Tregs, but not Th17 cells, from chronic hepatitis C patients expressed higher levels of TLR2 compared with NCs. Stimulation with Pam3Csk4 enhanced the suppressive function of Tregs and production of IL-10 in chronic hepatitis C more than in NCs. However, TLR2 stimulation did not promote Th17 differentiation of Tregs in chronic hepatitis C patients. Moreover, effective anti-HCV therapy resulted in the induction of IL-17-secreting phenotypic shift of Tregs without loss of inhibitive function upon TLR2 stimulation. These data provided a novel mechanism underlying modulating the balance of Tregs/Th17 cells in chronic hepatitis C. HCV infection shifted Tregs/Th17 cells through TLR2 stimulation by inducing Tregs to produce IL-10 and enhancing inhibitive function of effector T cells, resulting in viral persistence.

IFN-α promotes rapid human Treg contraction and late Th1-like Treg decrease

Type I IFNs are pleiotropic cytokines that exert concerted activities in the development of antiviral responses. Regulatory T cells represent a physiologic checkpoint in the balance between immunity and tolerance, requiring fine and rapid controls. Here, we show that human regulatory T cells are particularly sensitive to the sequential effects of IFN-α. First, IFN-α exerts a rapid, antiproliferative and proapoptotic effect in vitro and in vivo, as early as after 2 d of pegylated IFN/ribavirin therapy in patients with chronic hepatitis C. Such activities result in the decline, at d 2, in circulating regulatory T cell frequency and specifically of the activated regulatory T cell subset. Later, IFN-based therapy restrains the fraction of regulatory T cells that can be polarized into IFN-γ-producing Th1-like regulatory T cells known to contribute to chronic immune activation in type 1 inflammation. Indeed, Th1-like regulatory T cell frequency significantly declines after 30 d of therapy in vivo in relation to the persistent decline of relevant IL-12 sources, namely, myeloid and 6-sulfo LacNAc-expressing dendritic cells. This event is recapitulated by experiments in vitro, providing evidence that it may be attributable to the inhibitory effect of IFN-α on IL-12-induced, Th1-like regulatory T cell polarization. In summary, our results suggest that IFN-α-driven, early regulatory T cell depletion contributes to the development of antiviral immunity, ultimately resulting in the resolution of type 1 inflammation.

Expression profile and kinetics of cytokines and chemokines in patients with chronic hepatitis C

Cytokines and chemokines play an important role in defense against viral infection and modulating immune response. However, expression prolife of serum cytokines and chemokines, which were associated with the outcome of patients in response to anti-HCV treatment have not been fully elucidated. The current study aimed to determine the expression pattern of cytokines and chemokines in chronic HCV infection and their association with outcome in response to therapy. Seventy-two patients with HCV infection were enrolled, and fifty-one received peg-interferon α-2a and ribavirin therapy for 48 weeks. Thirty-nine cytokines and chemokines were analyzed by Luminex 200 and ELISA. In comparison to healthy individuals, production of IL-8 and IL-10 were increased in chronic hepatitis C patients. In contrast, IFN-γ, IL-7, and IL-15 were remarkably decreased, especially in HCV genotype 1b infection. HCV RNA load is closely associated with IL-10 and IL-15 expressions, and inhibition of HCV replication was accompanied by reduction in IL-10 and elevation in IL-7 and IL-15. Skewed cytokines and chemokines expression existed in chronic HCV infection, and might play an important role in persistent HCV infection. Exploiting the expression pattern of cytokines and chemokines may help to develop a better understanding of the pathogenesis of chronic HCV infection.

Role of Regulatory T Cells (Treg) and the Treg Effector Molecule Fibrinogen-like Protein 2 in Alloimmunity and Autoimmunity

CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg) are critical to the maintenance of immune tolerance. Treg are known to utilize a number of molecular pathways to control immune responses and maintain immune homeostasis. Fibrinogen-like protein 2 (FGL2) has been identified by a number of investigators as an important immunosuppressive effector of Treg, which exerts its immunoregulatory activity by binding to inhibitory FcγRIIB receptors expressed on antigen-presenting cells including dendritic cells, endothelial cells, and B cells. More recently, it has been suggested that FGL2 accounts for the immunosuppressive activity of a highly suppressive subset of Treg that express T cell immunoreceptor with Ig and ITIM domains (TIGIT). Here we discuss the important role of Treg and FGL2 in preventing alloimmune and autoimmune disease. The FGL2-FcγRIIB pathway is also known to be utilized by viruses and tumor cells to evade immune surveillance. Moving forward, therapies based on modulation of the FGL2-FcγRIIB pathway hold promise for the treatment of a wide variety of conditions ranging from autoimmunity to cancer.