Study of liver-targeted regulatory T cells in hepatitis B and C virus in chronically infected patients

The -3279C>A and -924A>G polymorphisms in the FOXP3 Gene Are Associated With Viral Load and Liver Enzyme Levels in Patients With Chronic Viral Liver Diseases

The transcription factor FOXP3 is an essential marker of the development and activation of regulatory T cells (Tregs), which are cells specialized in the regulation and normal tolerance of the immune response. In the context of chronic viral liver diseases, Tregs participate in the maintenance of infections by promoting histopathological control and favor the immune escape of viral agents by suppressing the antiviral response. Single nucleotide polymorphisms (SNPs) may influence the function of FOXP3 in a number of pathological conditions. The present study sought to evaluate the influence of SNPs in the FOXP3 gene promoter region in patients with chronic viral liver diseases. Three SNPs (−3279C>A, −2383C>T, and −924A>G) were analyzed in groups of patients with chronic hepatitis C (CHC), active chronic hepatitis B (CHB-A), inactive chronic hepatitis B (CHB-I), and a healthy control group (CG) using real-time PCR. The frequencies of the polymorphic variants were compared between groups and correlated with liver histopathological characteristics and enzyme levels [i.e., alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase (GGT)] obtained via biopsy and from the clinical records of the participating patients, respectively. For the −2338C>T SNP, no significant differences were found in the frequencies of variants between groups or in the histological findings. Significant associations between the polymorphisms and the CHB-I group were not established. The −3279C>A SNP was associated with altered viral loads (log₁₀) and GGT levels in CHC patients with advanced stages of inflammatory activity and liver fibrosis. The −924A>G SNP was associated with altered viral loads (log₁₀) and liver enzyme levels among CHB-A patients with milder inflammation and fibrosis. However, the frequencies of the −3279C>A and −924A>G polymorphisms were not directly associated with the histopathological profiles of the analyzed patients. These polymorphic variants may influence hepatic function in patients with chronic viral liver diseases but are not directly associated with the establishment of the degree of inflammatory activity and liver fibrosis.

Expression profiles of transcription factors for special CD4+ T-cell subsets in peripheral blood mononuclear cells from patients with hepatitis B virus infection

This study is to characterize the transcription factor expression profiles for the peripheral CD4 T-cell subsets, and analyze its associations with the clinical measures of the hepatitis B virus (HBV) infection.Totally 275 subjects were included. The expression levels of transcription factors (T-bet, GATA-3, Foxp3, RORγt, and Bcl-6) in the peripheral blood mononuclear cells (PBMCs) were determined by the real-time fluorimetry quantitative PCR (FQ-PCR).Lowest expression levels of all these transcription factors were observed for the HBsAb(-) group, which were higher in the HBsAb(+) and RHB groups. The T-bet/GATA-3 ratios in the CHB and RHB groups were significantly lower than the HBsAb(-) group, whereas the RORγt/Foxp3 ratios in the AHB and RHB groups were significantly higher than the CHB and HBsAb(+) groups. Furthermore, the RORγt mRNA expression levels were significantly different among groups with different disease severities or with different alanine aminotransferase (ALT) levels. The asymptomatic carrier (AsC) group and the group with ALT ≤ 40 had the highest express level. The mRNA expression levels of T-bet, GATA-3, Foxp3, and RORγt varied along with the aspartate aminotransferase (AST) levels, with AST ≤ 40 having the highest expression levels. In addition, significant differences were observed in the transcription factor expression levels between the group with the serum HBV DNA load of (1.000-9.999) × 10 copies/mL and other groups.Expression profile of critical transcription factors for peripheral CD4 T-cell subsets may indicate clinical outcomes of HBV infection.

Low hepatitis B virus-specific T-cell response in males correlates with high regulatory T-cell numbers in murine models

Hepatitis B virus (HBV) infection shows significant gender-related differences in pathogenesis, disease progression, and development of hepatocellular carcinoma. The gender-associated differences in HBV replication and viral protein levels may be associated with distinct HBV-specific immune responses in the host. In the present study, we examined the impact of gender on HBV-specific immune responses in two different mouse models representing transient and persistent hepadnaviral infection; hydrodynamic injection with the HBV genome mimicked acute HBV infection, whereas the efficacy of therapeutic vaccination was studied in the woodchuck hepatitis virus transgenic mouse model. Consistent with previous reports, significantly higher HBV DNA and protein levels were detected in male compared to female mice. Although hydrodynamic injection with the HBV genome resulted in similar numbers of intrahepatic HBV-specific cluster of differentiation 8-positive (CD8⁺ ) T cells, their functionality was significantly reduced in males and correlated with higher numbers of intrahepatic regulatory T cells (Tregs). Similar effects were observed in woodchuck hepatitis virus transgenic mice immunized with a DNA prime-recombinant adenovirus boost vaccination protocol. Male mice showed functionally suppressed woodchuck hepatitis virus-specific CD8⁺ T-cell responses in the liver and significantly higher numbers of intrahepatic Tregs compared to females. Blockade of Treg responses in male mice led to augmented effector functions of specific CD8⁺ T cells and subsequently improved virus control in both models of transient and persistent hepadnaviral infection.

CONCLUSION

The functionality of virus-specific CD8⁺ T cells in male mice was suppressed by intrahepatic Tregs and inversely correlated with levels of hepadnaviral DNA and viral protein; the induction of intrahepatic Tregs by viral replication and/or protein levels may explain the gender-related differences in the outcomes of HBV infection and limit the success of immunotherapeutic strategies in male patients. (Hepatology 2017;66:69-83).

Regulatory T-cells promote hepatitis B virus infection and hepatocellular carcinoma progression

Regulatory T-cells (Tregs), known for their immune suppressive function, have been reported in higher numbers, with activated phenotypes and greater potency, in hepatitis B virus (HBV)-related liver diseases than in normal conditions. The numbers, phenotypes, and function of intrahepatic and/or tumor-infiltrating Tregs in HBV-related liver diseases also differ from those of Tregs in the peripheral blood. By inhibiting the function of effector T-cells (Teffs), Tregs play a substantial role in the formation and maintenance of the liver's suppressive microenvironment, which might account for the progression of HBV-related hepatitis and hepatocellular carcinoma (HCC). In acute hepatitis B virus infection, Tregs can safeguard the liver from damage at the cost of prolonged antiviral processes, which results in chronic HBV infection in the liver. Furthermore, Tregs play a role in the development of cirrhosis, the transformation of cirrhosis to HCC, and the progression and metastasis of HCC. Higher levels of Tregs in the peripheral blood and/or tumor sites signify a poorer prognosis in HBV-related liver conditions, and observational data from mouse models and human patients support the theory that depleting Tregs may be therapeutic in HBV-related liver diseases by inducing antiviral and antitumor immunity.

Detection and significance of cytotoxic cell subsets in biopsies of HCV-infected human livers

Chronic viral hepatitis C still remains the clinical challenge. Attempts of the immune system to cope with this infection are unsatisfactory. There is a conviction that the main site of interaction between virus (Hepatitis C virus, HCV) and immune system is in situ, i.e., in liver. Natural killer (NK) cells appeared relevant in the acute hepatitis. Less is known about the immune response in the chronic HCV infection. The aim of this study was to evaluate the prevalence of various cytotoxic cell subsets in chronic HCV⁺ liver tissue and to seek links between them and laboratory data of patients. Sections from paraffin blocks of liver biopsy tissues of HCV⁺ untreated patients were subjected to the reaction with antibodies vs. cytotoxic cell subsets and immunohistochemistry. Positive cells were searched in cellular infiltrates in portal areas and in liver parenchyma. They were classified on the “Yes” or “No” basis. Majority of liver biopsies exhibited cellular infiltrates in portal spaces and as single cells in liver parenchyma. Infiltrates consisted of CD8⁺ T cells, CD56⁺ NK ones, including CD158i⁺ and CD158b⁺. The latter were rarely seen. There were also granzyme B⁺ cells. The most abundant were NKG2D⁺ cells, much more common than NK CD56⁺ ones. It implied that NKG2D was also expressed on T cells. Prevalence of NKG2D⁺ cells correlated with high activity of liver enzymes such as alanine aminotransferase, aspartate aminotransferase and a greater histological severity of liver injury. NKG2D⁺ cells form the bulk of cells infiltrating HCV-infected human liver. Correlation of NKG2D⁺ cells with some laboratory parameters of patients suggests their role in hepatitis C pathogenesis.

Expression levels of CD28, CTLA-4, PD-1 and Tim-3 as novel indicators of T-cell immune function in patients with chronic hepatitis B virus infection

Chronic hepatitis B (CHB) is one of the most common types of infectious diseases worldwide. The interaction between hepatitis B virus (HBV) and the host immune response is vital for the clinical outcome of HBV infection. Costimulatory signals are key factors for the host immune response and play a critical role in innate immunity, particularly antiviral immunity. The aim of the present study was to investigate the correlation between the expression levels of costimulatory molecules and the different states of CHB infection, including the expression levels prior to and following treatment with antiviral agents. The expression levels of CD28, CTLA-4, PD-1, Tim-3 and T-cell subsets were determined by flow cytometry. The load of HBV DNA in the serum was detected by quantitative polymerase chain reaction and the serology markers, including HBeAg and alanine aminotransferase (ALT), were measured by conventional methods. Compared to the healthy control group, the expression levels of CD28 and CTLA-4 on CD4 T cells prior to and following treatment with antiviral agents (the pre- and post-treatment groups, respectively) were significantly decreased, while the expression levels of Tim-3 on CD4 and CD8 T cells were significantly increased. In addition, the expression levels of PD-1 on CD4 and CD8 T cells in the pre-treatment group were significantly increased compared to those in the post-treatment and healthy control groups. Moreover, the multivariate analysis revealed that the levels of ALT and HBV-DNA in the serum were significantly positively correlated with PD-1 expression levels. In conclusion, the expression levels of these costimulatory molecules reflect the immune dysfunction of T cells in patients with CHB and, combined with T-cell subset analysis may be used as a novel evaluation system of immune function in patients with HBV infection.

Increased CD4+CD25+ regulatory T cells correlate with poor short-term outcomes in hepatitis B virus-related acute-on-chronic liver failure patients

BACKGROUND

The roles of CD4(+)CD25(+) regulatory T cells (Treg) in chronicity of hepatitis B virus (HBV) infection have been confirmed. We aimed to explore alteration of Treg in patients with HBV-related acute-on-chronic liver failure (ACLF).

METHODS

Thirty-two HBV-related ACLF patients, 44 chronic hepatitis B patients, and 41 healthy controls were recruited. We detected frequencies of peripheral Treg and intrahepatic forkhead winged helix transcription factor (Foxp3)(+) cells. Inhibitory activity of Treg was assessed by functional suppression assays. Serum interferon-γ and interleukin-10 were also determined.

RESULTS

Peripheral Treg and intrahepatic Foxp3(+) cells were more markedly increased in ACLF than chronic hepatitis B and controls (all p < 0.001), and the Foxp3(+) cells located predominantly in the portal areas. The Treg frequency was positively correlated with HBV DNA load, international normalized ratio, model of end stage liver disease score, and serum interleukin-10 level in ACLF patients. Functional assays in vitro demonstrated that ACLF patients exhibited higher suppressive effects of Treg on proliferations of autologous CD4(+)CD25(-) T cells than controls. On logistic regression, prolonged international normalized ratio and higher peripheral Treg frequency predicted 30-day survival of ACLF.

CONCLUSION

The patients with HBV-related ACLF exhibit increased amounts of Treg, of which redistribution from periphery to liver seems to modulate liver inflammation. Higher Treg amounts are associated with more severe liver disease in ACLF, and its level in combination with international normalized ratio may assist prediction of short-term outcomes of HBV-related ACLF.

Augmentation of hepatitis B virus-specific cellular immunity with programmed death receptor-1/programmed death receptor-L1 blockade in hepatitis B virus and HIV/hepatitis B virus coinfected patients treated with adefovir

The immunological parameters leading to viral persistence in chronic hepatitis B (CHB) are not clearly established. We analyzed HBV-specific immunoregulatory mechanisms in HIV-infected and HIV-uninfected HBeAg(+) CHB patients to determine (1) the roles of immunoregulatory pathways, (2) the effect of anti-HBV therapy on immunoregulatory pathways, and (3) the role of immunomodulatory therapy to overcome the effect of T regulatory cells (Tregs, CD4(+)CD25(+)FoxP3(+)) in HBV-infected individuals. A prospective, double blind, randomized, placebo-controlled trial treated HBV (HIV(+/-))-infected patients with adefovir 10 mg daily or placebo for 48 weeks. HBV viral load (VL), immunophenotying, and functional studies were performed at multiple time points. Suppression of HBV VL with adefovir leads to decreased peripheral expansion of Tregs. While declining, Tregs significantly inhibit cytokine-secreting HBV-specific CD8(+) T cell responses over 48 weeks of anti-HBV adefovir therapy (p<0.05). A large proportion of these Tregs express programmed death receptor-1 (PD-1), blockade of which in vitro leads to improved cytokine-secreting HBV-specific CD8(+) T cell responses, particularly in HIV/HBV-coinfected patients (p<0.05). Peripheral expansion of Treg levels correlated with HBV viral load and decreased HBV-specific CD8(+) T cells. PD-1 blockade increased survival of HBV-specific CD8(+) T cells, removing the inhibitory effect of PD-1(+) peripheral Tregs. Hence therapies involving PD-1 blockade in combination with directly acting antivirals should be investigated to reduce the need for life-long directly acting antiviral therapy.

Immunology of hepatitis C virus infections

The immune response in patients chronically infected with HCV plays a unique role during the infection because of its potential to contribute not only to viral clearance and, in some cases, protective immunity, but also to liver injury. A detailed understanding of the immunological mechanisms involved in persistence to HCV is essential to fully appreciate the complexity of the disease. In recent years, enormous progress has been made to characterize the dysfunctional natural killer cells and T cells during the chronic phase of infection. This information is important to further optimize treatment strategies based on the strengthening antiviral and immunomodulatory activities in patients chronically infected with HCV.

Regulatory T cells are the most important determinant factor of hepatitis B infection prognosis: a systematic review and meta-analysis

INTRODUCTION

Association of increased levels of CD4(+)CD25(+) regulatory T cells (Tregs) with impaired immune response and hepatitis B infection progression has been proposed. For determination of Tregs various effects among hepatitis B infected patients we performed a meta-analysis of the available literature.

METHODS

Current content, abstract books of congresses, and electronic databases were searched. Critical appraisal has been done. According to the result of heterogeneity tests (Q, I-squared, and Tau-squared), we used fix/random model for analysis.

RESULT

Twelve studies that fulfilled inclusion criteria entered to analysis. Pooled estimation of reported results showed that CD4(+)CD25(+) Tregs have higher expression of forkhead box P3 (FoxP3) versus CD4(+)CD25(-) Tregs, odd ratio (OR) was 31.49 (95% Confidence Intervals (CI): 5.09-194.94). Tregs level among chronic hepatitis B (CHB) patients was 77% (OR=1.77 95% CI: 1.43-2.19) higher than healthy controls. Patients with more than 10,000,000 HBV copies/ml have higher level of Tregs (OR: 1.24 95% CI: 1.08-1.41) comparing subjects with less than that. CHB patients have increased level of Tregs versus acute hepatitis B patients (OR=1.33 95% CI: 1.16-1.52). CD8 cells activity increased significantly after depletion of circulating Tregs (OR=1.93 CI: 1.37-2.73). Also, Tregs reduce response to treatment and non-responders to INF-α had higher level of Tregs (OR=1.60 95% CI: 1.09-2.36). In addition, Tregs increase risk of hepatocellular carcinoma (HCC) (OR=1.36 95%CI: 1.10-1.69).

CONCLUSION

Tregs influence HBV infected patients in various states. Tregs determine the disease prognosis by leading to infection progression and impairing immune response. So, Tregs are therapeutic target for immunotherapy of HBV infection.

CD56+ T cells inhibit HIV-1 infection of macrophages

CD56+ T cells, the crucial component of the host innate immune system, play an important role in defense against viral infections. We investigated the noncytolytic anti-HIV-1 activity of primary CD56+ T cells. SNs collected from CD56+ T cell cultures inhibited HIV-1 infection and replication. This CD56+ T SN-mediated anti-HIV-1 activity was broad-spectrum, as CD56+ T SNs could inhibit infections by laboratory-adapted and clinical strains of HIV-1. The antibody to IFN-γ could partially block the CD56+ T SN-mediated anti-HIV effect. Investigation of mechanism(s) of the CD56+ T cell action on HIV-1 showed that although CD56+ T SN had little effect on HIV-1 entry coreceptor CCR5 expression, CD56+ T SN induced the expression of CC-chemokines, the ligands for CCR5. The antibodies to CC-chemokines also significantly blocked CD56+ T SN-mediated anti-HIV activity. Furthermore, CD56+ T SN up-regulated the expression of STAT-1/-2 and enhanced the expression of IRF1, -3, -7, and -9, resulting in the induction of endogenous IFN-α/β expression in macrophages. Moreover, CD56+ T SN up-regulated intracellular expression of APOBEC3G/3F, the recently identified HIV-1 restriction factors. These findings provide compelling evidence that CD56+ T cells may have a critical role in innate immunity against HIV-1 infection.

Relations of regulatory T cells with hepatitis markers in chronic hepatitis B virus infection

To assess regulatory T cells (Treg) in chronic hepatitis B (CHB) infected patients and to evaluate the presence of a possible relation between them and hepatitis B markers, flow cytometry analysis was carried out to calculate the percentages of Tregs, Tregs secreting IL-10 and CD4(+) T cells secreting interferon-γ (IFN-γ) and enzyme-linked immunosorbent assay was used to detect hepatitis B virus (HBV) markers in 59 patients and 32 healthy controls. CD4(+)CD25(+), CD4(+)CD25(+)Foxp3(+), CD4(+)D25(high), CD4(+)CD25(high)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells and Treg cells secreting IL-10 were higher in CHB patients than in healthy controls. CD4(+)CD25(+), CD4(+)CD25(-), and total CD4(+)T cells secreting IFN-γ were generally lower in CHB patients than in healthy controls. Fair correlations were observed between CD4(+)CD25(+)Foxp3(+) T cells and alanine aminotransferase (ALT) levels and between HBsAb and both CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(high)Foxp3(+) T cells. CD4(+)CD25(+) T cells were significantly higher in CHB virus infected patients positive for HBeAg than in those negative for HBeAg and a good correlation was observed between CD4(+)CD25(+) T cells and HBeAg. Fair negative correlations were observed between CD4(+)CD25(high) T cells and both HBeAb and HBcAb. These data suggest that Tregs contribute to viral persistence. It was not possible to say that Tregs were the cause of immune suppression in this group of patients.

Study of cellular immune response against Hepatitis E virus (HEV)

Hepatitis E virus infection (HEV) is a major cause of acute viral hepatitis in the developing world. The immunopathology of HEV infections has not yet been elucidated. The virus is noncytopathic, and therefore, liver injury may be attributed to immune-mediated damage by cytotoxic T cells and natural killer cells. Therefore, we studied the nature of immune cells involved in HEV-induced liver damage using immunohistochemistry in liver biopsies taken from patients with HEV-induced acute liver failure and demonstrated a significant infiltration of activated CD8(+) T cells containing granzymes. These findings suggest the possible involvement of cytotoxic T cells in disease pathogenesis during HEV infection.

Retention of CD4+ CD25+ FoxP3+ regulatory T cells in the liver after therapy-induced hepatitis C virus eradication in humans

Following infection with the hepatitis C virus (HCV), in most cases immunity fails to eradicate the virus, resulting in slowly progressing immunopathology in the HCV-infected liver. We are the first to examine intrahepatic T cells and CD4(+) CD25(+) FoxP3(+) regulatory T cells (Treg) in patients chronically infected with HCV (chronic HCV patients) during and after antiviral therapy by collecting multiple aspiration biopsy samples from the liver at different time points. We found that intrahepatic Treg frequencies were increased upon alpha interferon and ribavirin administration in about 50% of chronic HCV patients, suggesting stronger regulation of intrahepatic immunity by Treg during antiviral therapy. After cessation of antiviral therapy, the frequency of intrahepatic Treg remained above baseline in the large majority of livers of individuals who successfully cleared the virus. The phenotype of those Treg that were retained in the liver months after therapy-induced clearance of HCV RNA indicated a reduced contribution of effector memory cells. Our findings, gathered by multiple samplings of the liver, indicate that successful antiviral therapy of chronic HCV patients does not lead to normalization of the local immune response to a resting state comparable to that for healthy livers. The continuous presence of high numbers of Treg, with a phenotype reflecting a relatively weak suppressive activity, suggests ongoing residual regulation of immunopathology. These findings provide important insight into the dynamics of the immune response to HCV, as well as the effect of therapy on intrahepatic immunity.

Are FoxP3(+) cells involved in hyporesponsiveness to interferon/ribavirin therapy in chronic hepatitis C?

We aimed to clarify the role of liver-infiltrating FoxP3(+) T cells for the response to therapy in chronic hepatitis C. Liver biopsies from 52 patients were collected prior to the start of interferon/ribavirin treatment, and the kinetics of viral decay during treatment were compared in patients with high and low infiltration of FoxP3(+) cells. These groups did not differ with respect to the effectiveness of early viral clearance or the frequency of sustained viral response. Our data imply that FoxP3(+) cell-mediated immunosuppression is not a major mechanism of hyporesponsiveness to interferon-based therapy in chronic hepatitis C.

Abundant numbers of regulatory T cells localize to the liver of chronic hepatitis C infected patients and limit the extent of fibrosis

BACKGROUND & AIMS

Weak hepatitis C virus (HCV) specific immunity in peripheral blood has been shown to be partially controlled by regulatory T cells (Treg). However, little is known about Treg present in livers of HCV-infected patients, their association with clinical parameters, and immunopathology resulting in disease progression.

METHODS

The frequency and phenotype of CD4+FoxP3+ Treg, conventional CD4+ T cells, and the distribution of lymphocytes and leukocytes were studied by multi-color flowcytometry in liver and peripheral blood of 43 chronic HCV patients at different phases of liver disease. Comparisons between healthy blood and liver and correlations with disease parameters were made.

RESULTS

An extensive lymphocyte infiltration containing abundant numbers of CD4+FoxP3+ Treg was present in HCV-infected livers, while absent from healthy liver. Moreover, in all patients, intrahepatic CD4+FoxP3+ Treg showed a fully differentiated and highly activated phenotype on the basis of the surface markers CD45RO, CCR7, CTLA-4 and HLA-DR. These Treg were more numerous in those HCV-infected livers showing only limited fibrosis. However, HCV RNA loads or alanine transaminase levels did not correlate with CD4+FoxP3+ Treg frequencies.

CONCLUSIONS

Our data demonstrate that large numbers of highly activated and differentiated CD4+FoxP3+ Treg localize to the infiltrated chronic HCV-infected liver and may result in limiting the extent of fibrosis. This suggests that CD4+FoxP3+ Treg play a pivotal role in limiting collateral damage by suppressing excessive HCV-induced immune activation.