Intrahepatic status of regulatory T cells in autoimmune liver diseases and chronic viral hepatitis

Histological changes in patients who developed hepatocellular carcinoma after hepatitis C virus eradication by interferon-based therapy

Although the incidence of hepatocellular carcinoma (HCC) occurring after hepatitis C virus (HCV) eradication has decreased, there are still reports of hepatocarcinogenesis. The present study investigated the histological changes of non-cancerous liver tissue obtained prior to interferon (IFN) therapy and after HCC development. A total of 669 HCV-infected Japanese patients who achieved sustained virological response (SVR) by IFN-based therapy were retrospectively enrolled. Of these, the present study investigated 18 patients who developed HCC after IFN-based SVR. Specimens from 9 of 18 patients were available for histological comparisons prior to IFN therapy and following HCC development. Of these 9 patients, the specimens of 5 individuals were compared via immunohistochemical staining [CD3, CD4, CD8, CD20, forkhead box P3 (FOXP3), transforming growth factor-β1 and granzyme B]. The current study included 6 control patients with HCV-associated chronic liver disease who subsequently developed HCC (non-SVR-HCC group). Mann-Whitney and Wilcoxon tests were used to compare groups. Bonferroni correction was used for multiple comparisons. P<0.05 was used as a critical P-value, and following Bonferroni's correction, P<0.017 was considered to indicate a statistically significant difference. In the 9 patients examined, continuous inflammation and fibrosis were observed after HCC development. There was also a significant decrease in the positive rate of FOXP3 in all 5 patients at the time of HCC development compared with that prior to IFN therapy (P=0.0084). Additionally, there was a significant difference in the positive rate of FOXP3 between the 5 patients after HCC development and the control individuals (P=0.0022). In patients who developed HCC after IFN-based SVR, the frequency of FOXP3 decreased, but inflammation and fibrosis remained. The extent of the reduction of FOXP3 differed in patients who developed HCC in the presence of HCV. Inflammation and fibrosis remained for a long duration after SVR, which may be associated with hepatocarcinogenesis.

Hepatitis C Virus Infection: Host⁻Virus Interaction and Mechanisms of Viral Persistence

Hepatitis C (HCV) is a major cause of liver disease, in which a third of individuals with chronic HCV infections may develop liver cirrhosis. In a chronic HCV infection, host immune factors along with the actions of HCV proteins that promote viral persistence and dysregulation of the immune system have an impact on immunopathogenesis of HCV-induced hepatitis. The genome of HCV encodes a single polyprotein, which is translated and processed into structural and nonstructural proteins. These HCV proteins are the target of the innate and adaptive immune system of the host. Retinoic acid-inducible gene-I (RIG-I)-like receptors and Toll-like receptors are the main pattern recognition receptors that recognize HCV pathogen-associated molecular patterns. This interaction results in a downstream cascade that generates antiviral cytokines including interferons. The cytolysis of HCV-infected hepatocytes is mediated by perforin and granzyme B secreted by cytotoxic T lymphocyte (CTL) and natural killer (NK) cells, whereas noncytolytic HCV clearance is mediated by interferon gamma (IFN-γ) secreted by CTL and NK cells. A host-HCV interaction determines whether the acute phase of an HCV infection will undergo complete resolution or progress to the development of viral persistence with a consequential progression to chronic HCV infection. Furthermore, these host-HCV interactions could pose a challenge to developing an HCV vaccine. This review will focus on the role of the innate and adaptive immunity in HCV infection, the failure of the immune response to clear an HCV infection, and the factors that promote viral persistence.

Intratumoral depletion of regulatory T cells using CD25-targeted photodynamic therapy in a mouse melanoma model induces antitumoral immune responses

Tumor immunotherapy aims to overcome the immunosuppressive microenvironment within tumors, and various approaches have been developed. Tumor-associated T regulatory cells (Tregs) suppress the activation and expansion of tumor antigen-specific effector T cells, thus, providing a permissive environment for tumor growth. Therefore, optimal strategies need to be established to deplete tumor-infiltrated Tregs because systemic depletion of Tregs can result in reduced anti-tumor effector cells and autoimmunity. Here, to selectively deplete Tregs in tumors, we intratumorally injected anti-CD25 antibodies conjugated to Chlorin e6 (Ce6), a photosensitizer that absorbs light to generate reactive oxygen species. Local depletion of tumor-associated Tregs with photodynamic therapy (PDT) inhibited tumor growth, which was likely due to the altered tumor immune microenvironment that was characterized by increased infiltration of CD8+ effector T cells and the expression of IFN-γ and CD107a, which is a cytolytic granule exocytosis marker in tumor tissues. Furthermore, PDT-induced intratumoral Treg depletion did not influence adaptive immune responses in a murine influenza infection model. Thus, our results show that intratumoral Treg-targeted PDT could specifically modulate tumor microenvironments by depleting Tregs and could be used as a novel cancer immunotherapy technique.

Increased Incidence of Post-transplant Lymphoproliferative Disorder in Autoimmune Liver Disease: An Irish National Experience

BACKGROUND

Post-Transplant Lymphoproliferative Disorder (PTLD) is a well-recognized complication post solid organs transplant. PTLD represents a broad spectrum of abnormalities ranging from an infectious mononucleosis like illness to malignant lymphoma.

METHODS

A retrospective study was performed by collecting data of orthotopic liver transplant (OLT) patients in the National Liver Unit in Ireland from December 1993 to December 2014. Data was analyzed to identify PTLD patients and determine their demographic details, the indication for liver transplant, presenting symptoms, immunosuppression regimens, Epstein"Barr virus (EBV) status and PTLD outcome.

RESULTS

From a total of 756 liver transplants recipients, 20 patients (2.6%) were diagnosed with PTLD. The median time from OLT to PTLD diagnosis was 83 months. The main primary indication for OLT of the PTLD cohort was Autoimmune Liver Disease (AiLD) (n = 13, 65%, mainly primary sclerosing cholangitis (PSC) n = 8, 40%). The combined group of auto-immune hepatitis, PSC and primary biliary cholangitis had a significantly higher incidence of PTLD compared to other etiologies (P < 0.01). In AiLD PTLD subgroup, 61.5% were positive for EBV. Five patients (38.5%) had extra-nodal disease and 3 patients had CNS disease. 61% of PTLD AiLD patients (n = 8) achieved complete response following their treatment.

CONCLUSION

PTLD has high mortality however early diagnosis and complete remission are achievable. Our study suggests that the incidence of PTLD is increased in AiLD and notably PSC patients.

Intrahepatic mRNA Expression of FAS, FASL, and FOXP3 Genes Is Associated with the Pathophysiology of Chronic HCV Infection

This study aimed to evaluate the relative mRNA expression of Fas receptor (FAS), Fas ligand (FASL), and forkhead box protein 3 (FOXP3) in liver biopsy specimens obtained from patients with viral and non-viral chronic hepatitis and correlate their expression with the fibrosis stage. A total of 51 liver biopsy specimens obtained from HBV (n = 6), HCV (n = 28), and non-viral hepatic disease (NVHD) (n = 9) patients and from individuals with normal liver histology (n = 8) (control—CT) were analyzed. Quantifications of the target genes were assessed using qPCR, and liver biopsies according to the METAVIR classification. The mRNA expression levels of FAS and FASL were lower in the CT group compared to the groups of patients. The increase in the mRNA expression of FAS and FASL was correlated with higher levels of inflammation and disease progression, followed by a decline in tissues with cirrhosis, and it was also associated with increased levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Higher mRNA expression of FOXP3 was observed in the HCV and NVHD groups, with the peak observed among patients with cirrhosis. The increased FOXP3 mRNA expression was positively correlated with increased FAS and FASL mRNA expression and the AST and ALT levels in all patients. Conclusions: These results suggest that regardless of the cause, the course of chronic liver disease may be modulated by the analyzed genes and correlated with an increase in regulatory T cells during the liver damage followed by hepatocyte destruction by Fas/FasL system and subsequent non specific lymphocytic infiltrate accumulation.

Peak inflammation in atherosclerosis, primary biliary cirrhosis and autoimmune arthritis is counter-intuitively associated with regulatory T cell enrichment

Regulatory T cells (Treg) influence the development of autoimmunity and their use is increasingly proposed for clinical applications. The well-characterized suppressive potential of Treg frequently leads to the assumption that Treg presence in prevailing numbers is indicative of immunosuppression. We hypothesized that this assumption may be false. We examined models of three different diseases caused by organ-specific autoimmune responses: primary biliary cirrhosis, atherosclerosis and rheumatoid arthritis (RA). We examined indicators of relative abundance of Treg compared to pro-inflammatory T cells, during peak inflammation. In all cases, the results were compatible with a relative enrichment of Treg at the site of inflammation or its most proximal draining lymph node. Conversely, in healthy mice or mice successfully protected from disease via a Treg-mediated mechanism, the data did not suggest that any Treg accumulation was occurring. This counter-intuitive finding may appear to be at odds with the immunosuppressive nature of Treg. Yet extensive previous studies in RA show that an accumulation of Treg occurs at peak inflammation, albeit without resulting in suppression, as the Treg suppressive function is overcome by the cytokine-rich environment. We suggest that this is a ubiquitous feature of autoimmune inflammation. Treg abundance in patient samples is increasingly used as an indicator of a state of immunosuppression. We conclude that this strategy should be revisited as it may potentially be a source of misinterpretation.

Intrahepatic regulatory T cells in autoimmune hepatitis are associated with treatment response and depleted with current therapies

BACKGROUND & AIMS

Autoimmune hepatitis (AIH) is a chronic autoimmune liver disease usually requiring life-long immunosuppression. The mechanisms for disease initiation and chronicity are largely unknown. A contribution of deficient regulatory T cells (Tregs) in the blood was controversially discussed recently. So far investigations in the target organ have been limited to single parameter analysis in untreated AIH.

METHODS

We retrospectively analysed the pattern of liver infiltrating T, B and regulatory T cells quantitatively with simultaneous multicolour immunofluorescence before (n=45) and under (n=31) therapy in adult AIH type 1 (AIH-1) patients.

RESULTS

Intrahepatic CD4(+) cells dominate over CD8(+) at diagnosis, but with increasing disease activity the CD4(+)/CD8(+) ratio approached one. While there is no change of Tregs in the blood, they are enriched with effector T cells (Teffs) within the liver of patients with untreated AIH-1 with a constant Treg/Teff ratio. Even more importantly, immunosuppression mostly with steroids and azathioprine caused a disproportional loss of intrahepatic Tregs. Patients reaching biochemical remission had higher intrahepatic Treg/Teff and Treg/B cell ratios compared to patients failing to reach remission. In vitro proliferation of Tregs seemed to be more suppressed by prednisolone than expansion of Teffs. Furthermore, intraportal B cells correlated with serum IgG suggesting an autochthonous intrahepatic IgG production.

CONCLUSIONS

Intrahepatic Tregs are rather enriched than numerically deficient in untreated AIH-1. The disproportional decrease of intrahepatic Tregs during therapy might explain high relapse rates after discontinuation of immunosuppression. Thus, future therapies increasing intrahepatic immunoregulation might be better suited for long-term control of AIH.

Influence of splenectomy in patients with liver cirrhosis and hypersplenism

AIM

Splenectomy improves hypersplenic thrombocytopenia in cirrhotic patients with hypersplenism. However, the long-term influence of splenectomy has not been clarified. We examined whether splenectomy improved liver fibrosis and caused immunological changes.

METHODS

We collected liver and spleen specimens and peripheral blood (PB) from 26 patients with hepatitis C virus-related liver cirrhosis. An immunohistochemical examination of CD4, CD8, forkhead box P3, granzyme B and transforming growth factor-β1, and Masson-trichrome stain were performed in spleen and liver tissues and in seven cases of follow-up liver biopsy sections obtained after splenectomy. We obtained PB before and at various intervals after splenectomy. We also examined the ratio of CD4(+) and CD8(+) lymphocytes in PB using flow cytometry.

RESULTS

We observed improvements in liver fibrosis in four biopsy specimens obtained after splenectomy, in which fibrotic areas significantly decreased from 19.5% to 8.2% (P < 0.05). Increases were also observed in the ratio of CD8(+) cells in PB after splenectomy, which resulted in a significant decrease in the CD4(+) /CD8(+) ratio (P < 0.001). The carcinogenic rate in patients with a CD4(+)  : CD8(+) ratio that decreased by more than 0.5 at 1 month after splenectomy was significantly lower than that in patients with a ratio that decreased by less than 0.5 (P < 0.05).

CONCLUSION

Splenectomy may improve liver fibrosis and cause beneficial immunological changes in cirrhotic patients with hepatitis. Improvements in antitumor mechanisms can be also expected.

Review article: chemokines as orchestrators of autoimmune hepatitis and potential therapeutic targets

BACKGROUND

Chemokines contribute to the pathogenesis of autoimmune hepatitis by directing the migration and positioning of inflammatory and immune cells within the liver.

AIM

Describe the liver-infiltrating effector cell populations in autoimmune hepatitis, indicate the chemokines that influence their migration, describe the role of chemokines in hepatic fibrosis and identify chemokine-directed treatment opportunities.

METHODS

Studies cited in Pub Med from 1972 to 2014 for autoimmune hepatitis, chemokines in liver disease, pathogenesis of autoimmune hepatitis and chemokine therapy were selected.

RESULTS

T helper type 17 lymphocytes expressing CXCR3 and CCR6 are attracted to the liver by the secretion of CXCL9, CXCL10 and CXCL11. These cells recruit pro-inflammatory T helper type 1 lymphocytes expressing CXCR3 and CCR5 by secreting CXCL10. Resident natural killer T cells expressing CXCR6 migrate in response to the local secretion of CXCL16, and they modulate the inflammatory response. T helper type 2 lymphocytes expressing CCR4 are attracted by CCL17 and CCL22, and they dampen the expansion of pro-inflammatory cells. Regulatory T cells expressing CXCR3 are attracted by the secretion of CXCL9, and they help dampen the pro-inflammatory responses. CCL2, CCL3, CCL5, CXCL4, CXCL10 and CXCL16 promote fibrosis by activating or attracting hepatic stellate cells, and CX3CL1 may prevent fibrosis by affecting the apoptosis of monocytes.

CONCLUSIONS

Chemokines are requisites for mobilising, directing and positioning the effector cells in immune-mediated liver disease. They are feasible therapeutic targets in autoimmune hepatitis, and the evaluation of monoclonal antibodies that neutralise the pro-inflammatory ligands or designer peptides that block receptor activity are investigational opportunities.

Abnormal peripheral blood lymphocyte subsets in patients with autoimmune hepatitis

AIM: To investigate the abnormal changes in peripheral blood lymphocyte subsets in patients with autoimmune hepatitis and to analyze their correlations with liver dysfunction, immunoglobulin (Ig) and hepatitis activity index (HAI) to explore the significance of abnormal lymphocyte subsets in the diagnosis and treatment of autoimmune hepatitis (AIH).

METHODS: Thirty-six patients who were diagnosed with AIH and did not accept prior immunosuppressive therapy were included. Thirty-six healthy subjects were used as controls. Patients in both groups received tests of liver function and immune function. Liver biopsy and histopathological examination were carried out to evaluate HAI score for AIH patients. The subsets of T lymphocytes, B lymphocytes and regulatory T cells (Tregs) were detected by flow cytometry (FCM). Correlations between the percentages of lymphocyte subgroups and liver function, Ig and HAI score were evaluated.

RESULTS: The percentages of CD3⁺CD4⁺ T, CD3⁺CD8⁺ T, CD19⁺ B,CD5⁺CD19⁺ B and the ratios of CD3⁺CD4⁺ T/CD3⁺CD8⁺ T and CD5⁺CD19⁺ B/CD19⁺ B cells were all significantly higher in AIH patients than in controls (all P < 0.05). However, there was no statistical significance in the percentage of CD4⁺CD25⁺CD127dim Tregs between the two groups. The percentages of CD3⁺CD4⁺ T, CD3⁺CD8⁺ T, and CD5⁺CD19⁺ B cells had a positive correlation with serum levels of alanine aminotransferase, aspartate aminotransferase and HAI score. The percentage of CD5⁺CD19⁺ B cells was positively related to IgG (r = 0.482, P < 0.01).

CONCLUSION: In AIH patients, abnormal peripheral blood T and B lymphocyte subsets may lead to the aggravation of liver injury. Cellular immunity mediated by T lymphocyte subsets may be more closely related to liver injury and hepatic inflammatory activity. Immuno-regulatory effect of regulatory T cells may not be obvious in AIH patients.

Interaction of hepatic stellate cells with diverse types of immune cells: foe or friend?

Activated hepatic stellate cells (HSCs) have been considered as a major type of cells in liver fibrosis by producing a huge amount of extracellular matrix, especially collagen fibers, and profibrotic mediators such as transforming growth factor-beta, interleukin-6 and monocyte chemoattractant protein-1. Recently, accumulated evidence suggests that the liver is an immunologic organ because of enrichment of diverse types of immune cells and that their interactions with HSCs are closely related with the progression of liver fibrosis. However, the underlying mechanisms of interaction between HSCs and immune cells remain largely unknown. Recently, several studies have demonstrated that natural killer cells, M2 macrophages, regulatory T cells, and bone marrow derived CD11b(+) Gr1(+) immature cells ameliorate liver fibrosis, whereas neutrophils, M1 macrophages, CD8 T cells, natural killer T cells and interleukin-17-producing cells accelerate liver fibrosis. However, there are still controversial issues about their functions during liver fibrogenesis. In this review, we summarize the diversity roles of immune cells (e.g. profibrotic/antifibrotic or both) in regulating the activation of HSCs during hepatic fibrogenesis, in which several producible mediators by HSCs play important roles in the interaction with them. Moreover, the current cell-based therapies using immune cells against liver fibrosis are discussed.

The immunology of fibrosis

Fibrosis is the production of excessive amounts of connective tissue, i.e., scar formation, in the course of reactive and reparative processes. Fibrosis develops as a consequence of various underlying diseases and presents a major diagnostically and therapeutically unsolved problem. In this review, we postulate that fibrosis is always a sequela of inflammatory processes and that the many different causes of fibrosis all channel into the same final stereotypical pathways. During the inflammatory phase, both innate and adaptive immune mechanisms are operative. This concept is exemplified by fibrotic diseases that develop as a consequence of tissue damage, primary inflammatory diseases, fibrotic alterations induced by foreign body implants, "spontaneous" fibrosis, and tumor-associated fibrotic changes.

The similarity of Type 1 autoimmune pancreatitis to pancreatic ductal adenocarcinoma with significant IgG4-positive plasma cell infiltration

BACKGROUND

High serum immunoglobulin G4 (IgG4) levels and infiltration of IgG4-positive cells are characteristic of Type 1 autoimmune pancreatitis (AIP). We previously reported that increased regulatory T cells (Tregs) may regulate IgG4 production in AIP. Although an increased serum IgG4 concentration is observed in some patients with pancreatic ductal adenocarcinoma (PDA), clarification is still necessary. We have therefore studied the correlations between IgG4-positive cells and Tregs in patients with PDA.

SUBJECTS AND METHODS

A total of 21 PDA and nine AIP patients were enrolled in our study. The numbers and ratios of Tregs, IgG4-positive, and IgG-positive cells immunohistochemically stained with anti-Foxp3, IgG4, and IgG antibodies, respectively, were counted in three areas of resected pancreata in PDA, peritumoral pancreatitis (PT), and obstructive pancreatitis (OP).

RESULTS

In PDA, PT, OP area, the number of IgG4-Positive cells (5.183 ± 1.061, 2.250 ± 0.431, 4.033 ± 1.018, respectively; p < 0.05) and the ratio of IgG4/IgG (0.391 ± 0.045, 0.259 ± 0.054, 0.210 ± 0.048, respectively; p < 0.05) were significantly lower than those in AIP (21.667 ± 2.436 and 0.306 ± 0.052, respectively). The numbers of IgG4-positive cells did not differ significantly among the three areas of resected pancreata examined. However, the IgG4/IgG (0.391 ± 0.045) and Foxp3/monocyte (0.051 ± 0.008) ratios in PDA area were significantly (p < 0.05) higher than those in OP area (IgG4/IgG: 0.210 ± 0.048; oxp3/monocyte: 0.0332 ± 0.005), but not in PT area. Of the 21 cases of PDA, the ratio of IgG4/IgG was >40 % in nine (43%), six (29%) and three (14%) cases in PDA, PT and OP area, respectively. Foxp3 and IgG4 were positively correlated in OP area, but not in PDA and PT area.

CONCLUSIONS

Clinicians should be careful when basing a differential diagnosis of PDA and AIP on the numbers of IgG4-positive cells and the ratio of IgG4/IgG, especially when determined using a small biopsied sample.

Decreased peripheral blood CD4+/CD25+ regulatory T cells in patients with alcoholic hepatitis

BACKGROUND

Development of alcoholic hepatitis (AH) may be favored by the activation of the innate immune response. Recently, decreased numbers of circulating regulatory T cells (Tregs) have been reported in diseases associated with an immune activation status, but no studies have focused so far, in investigating the distribution of Tregs in chronic alcoholism and its potential association with liver disease. Here, we analyzed for the first time the frequency of peripheral blood (PB) Tregs and Treg subsets in AH and its relationship with the production of inflammatory cytokines by PB monocytes and dendritic cells (DCs).

METHODS

PB samples from 25 male patients with AH were studied; in parallel, 15 male chronic alcoholic patients without liver disease (AWLD) and 17 male healthy donors were also studied, as controls. The distribution of CD4⁺CD25hiCD127-/lo Tregs and their maturation subsets (naïve, central memory, and peripheral memory Tregs) was analyzed by flow cytometry. Spontaneous and in vitro-stimulated production of inflammatory cytokines by PB monocytes and DCs was analyzed by flow cytometry at the cytoplasmic level.

RESULTS

Patients with AH showed decreased (p < 0.05) numbers of PB CD4⁺CD25hiCD127-/lo Tregs at the expense of all maturation-associated subsets, while AWLD and healthy subjects showed a similar (p > 0.05) distribution of PB CD4⁺CD25hiCD127-/lo Tregs. Interestingly, significantly increased amounts of spontaneously produced inflammatory cytokines were found among circulating monocyte-derived DCs and monocytes from AH (and AWLD) patients in comparison with healthy donors. Conversely, the ability of these cell subsets to produce cytokines after in vitro stimulation was lower (p < 0.05) in AH versus the 2 control groups.

CONCLUSIONS

PB CD4⁺CD25hiCD127-/lo Tregs are significantly decreased in patients with AH when compared to both healthy and AWLD; this may contribute to explain the more pronounced activation of the innate immune response observed in AH, as reflected by an increased secretion of inflammatory cytokines by PB DCs and monocytes, and could facilitate the development of liver disease.

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.

Cytomegalovirus-specific T-cell reactivity in biliary atresia at the time of diagnosis is associated with deficits in regulatory T cells

Biliary atresia (BA) is a progressive, inflammatory cholangiopathy that culminates in fibrosis of extrahepatic and intrahepatic bile ducts. A leading theory on the pathogenesis of BA is that the bile duct damage is initiated by a virus infection, followed by a bile duct-targeted autoimmune response. One mechanism of autoimmunity entails a diminished number or function of regulatory T cells (Tregs). The aim of this study was to identify potential virus-specific liver T cells from infants with BA at the time of diagnosis, implicating the virus involved in early bile duct damage. A subaim was to determine if the presence of virus infection was associated with quantitative changes in Tregs. Liver T cells from BA and control patients were cultured with antigen-presenting cells in the presence of a variety of viral or control proteins. 56% of BA patients had significant increases in interferon-gamma-producing liver T cells in response to cytomegalovirus (CMV), compared with minimal BA responses to other viruses or the control group CMV response. In addition, a positive correlation between BA plasma CMV immunoglobulin M (IgM) and liver T-cell CMV reactivity was identified. Investigation of peripheral blood Tregs revealed significant deficits in Treg frequencies in BA compared with controls, with marked deficits in those BA patients who were positive for CMV.

CONCLUSION

Liver T-cell responses to CMV were identified in the majority of BA patients at diagnosis, suggesting perinatal CMV infection as a plausible initiator of bile duct damage. Deficiency of Tregs in BA implies decreased inhibition of inflammation and autoreactivity, potentially allowing for exaggerated bile duct injury.

Foxp3 expression in liver correlates with the degree but not the cause of inflammation

Patients with chronic viral hepatitis display increased expression of Foxp3 in liver, suggesting that Tregs expansion contributes to persistent infection. The purpose of this study was to elucidate whether the expression of Foxp3 relates not to the viral infection but to the resulting liver inflammation. Liver biopsies obtained from 69 individuals (26 chronic HBV hepatitis, 14 chronic HCV hepatitis, 11 nonalcoholic fatty liver disease, 8 autoimmune diseases, 2 methotrexate-related toxicity, and 8 controls) were examined, by qRT-PCR, for the mRNA expression of Foxp3, IL-10, TGF-β1, Fas, FasL, TRAIL, caspase-3, TNF-α, IFN-γ, and IL-1β. Significant increase of Foxp3 was observed in all disease groups compared to controls, which was positively correlated with the intensity of inflammation. The expression of the apoptosis mediators Fas, FasL, and TRAIL, but not of IL-10 and TGF-β1, was also significantly elevated. Our findings indicate that, independently of the initial inducer, liver inflammation is correlated with elevated expression of apoptosis mediators and is followed by local Treg accumulation. Further research towards the elucidation of the underlying casual relationships is required, in order to clarify whether our results signify the existence of a uniform Treg-mediated regulatory mechanism of apoptosis-induced inflammation.

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.

β-Arrestin 1 modulates functions of autoimmune T cells from primary biliary cirrhosis patients

OBJECTIVES

Primary biliary cirrhosis (PBC) is an autoimmune disease, characterized by antimitochondrial antibodies and autoreactive T cells causing destruction of the primary bile ducts. The molecular mechanisms regulating the autoreactive T cells remain elusive. β-Arrestins (βarr) are multifunctional signaling molecules that are crucial to T cell survival. We hypothesized that βarr plays a critical regulatory function in the autoreactive T cells of PBC patients.

METHODS

Patients with hepatic biliary cirrhosis (n=60) were evaluated. Cytokine expression, T cell proliferation, and transcription factors were evaluated to assess regulatory functions in autoreactive T cells from the patient.

RESULTS

Our studies showed that expression of βarr1 was elevated significantly in T lymphocytes from patients with PBC. Moreover, the level of βarr1 mRNA positively correlated with Mayo risk score in PBC patients. Based on modulation of βarr in autoreactive T cell lines, overexpression of βarr1 increased T cell proliferation, augmented interferon production, downregulated activities of nuclear factor κB and AP-1, promoted acetylation of histone H4 in the promoter regions of CD40L, LIGHT, IL-17 and interferon-γ, while downregulating acetylation of histone H4 in the promoter regions of TRAIL, Apo2, and HDAC7A, thereby regulating expression of these genes.

CONCLUSIONS

Our findings suggest that βarr1 contributes to the pathogenesis of PBC, having significant implications for novel therapy strategy, further providing information for investigating the mechanisms of autoimmune disease.

Increased Siglec-1 expression in monocytes of patients with primary biliary cirrhosis

OBJECTIVES

To evaluate Siglec-1 protein (CD169) and mRNA levels in peripheral blood monocytes of patients with primary biliary cirrhosis (PBC) and investigate its role in PBC pathogenesis by looking for correlations between Siglec-1 expression and key PBC associated biochemical indices.

METHODS

FACS analysis was used to identify the percentage of peripheral blood monocytes positive for both CD14 and Siglec-1 in (a) 45 PBC patients, (b) 40 patients with liver cirrhosis after hepatitis B infection and (c) 36 healthy controls. Siglec-1 mRNA was measured by real-time RT-PCR and serum biomarkers by routine biochemistry.

RESULTS

The percentage of CD14-Siglec-1 double positive cells was significantly higher (p< 0.01) in PBC patients than in healthy controls or cirrhosis post-hepatitis patients (13.68 +/- 2.44%, 1.0 +/- 0.2 %, and 4.1 +/- 0.5 %, respectively). Siglec-1 mRNA expression in the PBC group was 3.42 times higher than in healthy controls (p < 0.01).

CONCLUSION

We investigated the role of Siglec-1 in PBC by assessing its expression in mononuclear cells of PBC patients and levels of secreted cytokines in cell supernatants after Siglec-1 RNA interference. It is possible that elevated Siglec-1 expression in peripheral blood monocytes of PBC patients is correlated with monocyte-mediated inflammatory responses during the development of PBC.

Cyclooxygenase-2 gene promoter polymorphisms affect susceptibility to hepatitis C virus infection and disease progression

AIM

  Because polymorphisms of cyclooxygenase-2 (COX-2) and osteopontin (OPN) promoter regions and a promoter/enhancer region of forkhead box protein 3 (FOXP3) gene are known to affect immune responses, we examined whether these polymorphisms can influence susceptibility to hepatitis C virus (HCV) infection and progression of liver disease.

METHODS

  Peripheral blood samples were obtained from 104 Japanese patients with chronic HCV infection and 74 healthy Japanese donors. Polymerase chain reaction single-stranded conformational polymorphism analysis of genomic DNA was performed to determine the polymorphisms.

RESULTS

  The risk of persistent HCV infection was decreased in subjects with -1195GG genotype of the COX-2 promoter region. However, in patients with chronic HCV infection, the -1195GG genotype was associated with advanced-stage liver disease. A luciferase reporter assay performed to analyze the effect of single nucleotide polymorphisms (SNP) (-1195A or -1195G) in COX-2 gene on transcriptional activity using the HepG2, Huh7 and HeLa cell lines indicated that the -1195G genotype showed higher transcriptional activity than the -1195A genotype. SNP of OPN and FOXP3 did not differ between patients with chronic HCV infection and controls. However, the -443TT genotype of the OPN promoter region was associated with increased inflammatory activity of the liver.

CONCLUSION

  These results suggest that the -1195GG genotype of the COX-2 promoter region protects against HCV infection in the Japanese. However, once chronic infection is established, the -443TT genotype of the OPN promoter region and the -1195GG genotype of the COX-2 promoter are thought to promote inflammation and contribute to the progression of liver disease.

CD4+ CD25+ but not CD4+ Foxp3+ T cells as a regulatory subset in primary biliary cirrhosis

Increasing evidence indicates a role for regulatory T cells (Tregs) in the immune response and in autoimmune diseases, but the role of Tregs and cytokines in autoimmune hepatic diseases remains largely unclear and controversial, especially in patients with primary biliary cirrhosis (PBC). This study was undertaken to investigate Tregs and different cytokines in the liver and peripheral blood of PBC patients. We found that these patients demonstrated a reduction of CD4(+)CD25(+) T cells but elevated CD4(+)Foxp3(+) T cells in peripheral blood mononuclear cells (PBMCs) and CD4(+) T cells. The percentage of CD4(+)CD25(+) T cells in PBMCs was negatively correlated with elevated plasma interferon (IFN)-γ levels. A liver-specific analysis showed that the frequency of Foxp3(+) Tregs, transforming growth factor (TGF)-β1 and IFN-γ were increased in PBC patients. Our findings suggest that an imbalance between CD4(+)CD25(+) Tregs and cytotoxic cytokines plays a crucial role in the pathogenesis of PBC while the role of Foxp3 needs further investigation.

Effect of allogeneic bone marrow-derived mesenchymal stem cells transplantation in a polyI:C-induced primary biliary cirrhosis mouse model

Primary biliary cirrhosis (PBC) is a slowly progressive autoimmune disease of unknown mechanism. We established a PBC animal model by injecting C57BL/6 mice with polyinosinic-polycytidylic acid sodium (polyI:C) to investigate the therapeutic effect of bone marrow-derived mesenchymal stem cells (BM-MSC) on this model. After 6 weeks of MSC infusion, serum aminotransferase and autoimmune antibodies declined, and histological examination by hematoxylin and eosin staining showed significant amelioration of monocytes infiltration around bile ducts of mice treated with BM-MSC. Interestingly, allogeneic BM-MSC transplantation markedly increased CD4(+)Foxp3(+) regulatory T cells in peripheral blood as well as in lymph nodes when analyzed by flow cytometry. Further examination showed serum TGF-β1 increased but IFN-γ decreased significantly in PBC mice treated with MSC, while with no obvious change in IL-10 expression. Our results for the first time suggested that BM-MSC transplantation could regulate systemic immune response and enhance recovery in liver inflammation of PBC mice, raising the possibility for clinical application of allogeneic MSC in treatment of early-stage PBC patients.

Phenotypical and functional alterations of CD8 regulatory T cells in primary biliary cirrhosis

The mechanisms that lead to loss of tolerance in autoimmune disease have remained both elusive and diverse, including both genetic predisposition and generic dysregulation of critical mononuclear cell subsets. In primary biliary cirrhosis (PBC), patients exhibit a multilineage response to the E2 component of pyruvate dehydrogenase involving antibody as well as autoreactive CD4 and CD8 responses. Recent data from murine models of PBC have suggested that a critical mechanism of biliary destruction is mediated by liver-infiltrating CD8 cells. Further, the number of autoreactive liver-infiltrating CD4 and CD8 cells is significantly higher in liver than blood in patients with PBC. Based on this data, we have studied the frequencies and phenotypic characterization of both CD4 and CD8 regulatory T cell components in both patients with PBC and age-sex matched controls. Our data is striking and indicate that CD8 Treg populations from PBC patients, but not controls, have significant phenotypic alterations, including increased expression of CD127 and reduced CD39. Furthermore, in vitro induction of CD8 Tregs by incubation with IL10 is significantly reduced in PBC patients. Importantly, the frequencies of circulating CD4+CD25+ and CD8+ and CD28- T cell subpopulations are not significantly different between patients and controls. In conclusion, these data identify the CD8 Treg subset as a regulatory T cell subpopulation altered in patients with PBC.

Analysis of regulatory T cells and IgG4-positive plasma cells among patients of IgG4-related sclerosing cholangitis and autoimmune liver diseases

OBJECTIVES

Patients with autoimmune pancreatitis (AIP) characteristically show elevated serum levels of immunoglobulin G4 (IgG4) and abundant infiltration of IgG4-positive plasmacytes in the involved organs. The most common involved organ showing extrapancreatic lesions is the bile duct, which exhibits sclerosing cholangitis (SC). However, the role of IgG4 in the development of IgG4-related SC (IgG4-SC) remains unclear. To clarify the role of IgG4 in IgG4-SC, we have performed an immunohistochemical analysis of the bile duct.

METHODS

Laboratory and immunohistochemical findings of liver biopsy specimens obtained from patients with IgG4-SC, primary sclerosing cholangitis (PSC), autoimmune hepatitis (AIH), and primary biliary cirrhosis (PBC) were compared. The biopsy specimens were first stained with anti-IgG1, anti-IgG4, and anti-Foxp3 (forkhead box P3) antibodies, and the ratio of IgG4-, IgG1-, and Foxp3-positive cells, respectively, to infiltrated mononuclear cells (IgG4/Mono, IgG1/Mono, Foxp3/Mono) was assessed.

RESULTS

The ratio of IgG4/IgG1-positive plasma cells was significantly higher in specimens obtained from patients with IgG4-SC than in those from patients with PSC, AIH, and PBC. The Foxp3/Mono ratio in patients with PBC was significantly higher than that in patients with IgG4-SC and PSC. In patients with IgG4-SC, the number of Foxp3-positive cells was significantly correlated with the number of IgG4-positive cells; in the other patient groups, there was no correlation.

CONCLUSIONS

The IgG4/IgG1 ratio in the liver may be a useful marker for differential diagnosis of IgG4-SC and PSC. In IgG4-SC, abundant infiltration of regulatory T cells (Tregs) may affect the switching of B cells to IgG4-producing plasmacytes, and there is a possibility that the function of Tregs is different in IgG4-SC and other liver diseases (PSC, AIH, and PBC).

Update on primary biliary cirrhosis

Primary biliary cirrhosis is an autoimmune chronic liver disease characterized by progressive bile duct destruction eventually leading to cirrhosis, liver failure, and death. The autoimmune pathogenesis is supported by a plethora of experimental and clinical data, such as the presence of autoreactive T cells and serum autoantibodies. The aetiology remains unknown, although evidence suggests a role for both genetic susceptibility and environmental factors that remain to be determined. In fact, a number of chemicals and infectious agents have been proposed to induce the disease in predisposed individuals. The recent availability of several murine models will significantly help in understanding pathophysiology mechanisms. In this review, we critically summarize the most recent data on the aetiopathogenesis of primary biliary cirrhosis, discuss the latest theories and developments, and suggest directions for future research.

Immune response of cytotoxic T lymphocytes and possibility of vaccine development for hepatitis C virus infection

Immune responses of cytotoxic T lymphocytes (CTLs) are implicated in viral eradication and the pathogenesis of hepatitis C. Weak CTL response against hepatitis C virus (HCV) may lead to a persistent infection. HCV infection impairs the function of HCV-specific CTLs; HCV proteins are thought to actively suppress host immune responses, including CTLs. Induction of a strong HCV-specific CTL response in HCV-infected patients can facilitate complete HCV clearance. Thus, the development of a vaccine that can induce potent CTL response against HCV is strongly expected. We investigated HCV-specific CTL responses by enzyme-linked immuno-spot assay and/or synthetic peptides and identified over 40 novel CTL epitopes in the HCV protein. Our findings may contribute to the development of the HCV vaccine. In this paper, we describe the CTL responses in HCV infection and the attempts at vaccine development based on recent scientific articles.

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.

Magnitude of CD8 T-cell responses against hepatitis C virus and severity of hepatitis do not necessarily determine outcomes in acute hepatitis C virus infection

AIM

We investigated the relationship between the magnitude of comprehensive hepatitis C virus (HCV)-specific CD8(+) T-cell responses and the clinical course of acute HCV infection.

METHODS

Six consecutive patients with acute HCV infection were studied. Analysis of HCV-specific CD8(+) T-cell responses was performed using an interferon-gamma-based enzyme-linked immunospot assay using peripheral CD8(+) T-cells, monocytes and 297 20-mer synthetic peptides overlapping by 10 residues and spanning the entire HCV sequence of genotype 1b.

RESULTS

Five patients presented detectable HCV-specific CD8(+) T-cell responses against a single and different peptide, whereas 1 patient showed responses against three different peptides. Neither the magnitude of HCV-specific CD8(+) T-cell responses nor the severity of hepatitis predicts the outcome of acute hepatitis. The maximum number of HCV-specific CD8(+) T-cells correlated with maximum serum alanine aminotransferase level during the course (r = 0.841, P = 0.036).

CONCLUSIONS

HCV-specific CD8(+) T-cell responses were detectable in all 6 patients with acute HCV infection, and 6 novel HCV-specific CTL epitopes were identified. Acute HCV infection can resolve with detectable HCV-specific CD8(+) T-cell responses, but without development of antibody against HCV.