Gene expression signatures of peripheral CD4+ T cells clearly discriminate between patients with acute and chronic hepatitis B infection

The dual role of regulatory T cells in hepatitis B virus infection and related hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major contributor to cancer-related deaths worldwide. Hepatitis B virus (HBV) infection is a major etiologic factor leading to HCC. While there have been significant advancements in controlling HBV replication, achieving a complete cure for HBV-related HCC (HBV-HCC) remains an intricate challenge. HBV persistence is attributed to a myriad of mechanisms, encompassing both innate and adaptive immune responses. Regulatory T cells (Tregs) are pivotal in upholding immune tolerance and modulating excessive immune activation. During HBV infection, Tregs mediate specific T cell suppression, thereby contributing to both persistent infection and the mitigation of liver inflammatory responses. Studies have demonstrated an augmented expression of circulating and intrahepatic Tregs in HBV-HCC, which correlates with impaired CD8+ T cell function. Consequently, Tregs play a dual role in the context of HBV infection and the progression of HBV-HCC. In this comprehensive review, we discuss pertinent studies concerning Tregs in HBV infection, HBV-related cirrhosis and HCC. Furthermore, we summarize Treg responses to antiviral therapy and provide Treg-targeted therapies specific to HBV and HCC.

Beyond HIV infection: Neglected and varied impacts of CCR5 and CCR5Δ32 on viral diseases

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CCR5 regulates multiple cell types (e.g., T regulatory and Natural Killer cells) and immune responses.

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The effects of CCR5, CCR5Δ32 (variant associated with reduced CCR5 expression) and CCR5 antagonists vary between infections.

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CCR5 affects the pathogenesis of flaviviruses, especially in the brain.

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The genetic variant CCR5Δ32 increases the risk of symptomatic West Nile virus infection.

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The triad “CCR5, extracellular vesicles and infections” is an emerging topic.

The interactions between chemokine receptors and their ligands may affect susceptibility to infectious diseases as well as their clinical manifestations. These interactions mediate both the traffic of inflammatory cells and virus-associated immune responses. In the context of viral infections, the human C-C chemokine receptor type 5 (CCR5) receives great attention from the scientific community due to its role as an HIV-1 co-receptor. The genetic variant CCR5Δ32 (32 base-pair deletion in CCR5 gene) impairs CCR5 expression on the cell surface and is associated with protection against HIV infection in homozygous individuals. Also, the genetic variant CCR5Δ32 modifies the CCR5-mediated inflammatory responses in various conditions, such as inflammatory and infectious diseases. CCR5 antagonists mimic, at least in part, the natural effects of the CCR5Δ32 in humans, which explains the growing interest in the potential benefits of using CCR5 modulators for the treatment of different diseases. Nevertheless, beyond HIV infection, understanding the effects of the CCR5Δ32 variant in multiple viral infections is essential to shed light on the potential effects of the CCR5 modulators from a broader perspective. In this context, this review discusses the involvement of CCR5 and the effects of the CCR5Δ32 in human infections caused by the following pathogens: West Nile virus, Influenza virus, Human papillomavirus, Hepatitis B virus, Hepatitis C virus, Poliovirus, Dengue virus, Human cytomegalovirus, Crimean-Congo hemorrhagic fever virus, Enterovirus, Japanese encephalitis virus, and Hantavirus. Subsequently, this review addresses the impacts of CCR5 gene editing and CCR5 modulation on health and viral diseases. Also, this article connects recent findings regarding extracellular vesicles (e.g., exosomes), viruses, and CCR5. Neglected and emerging topics in “CCR5 research” are briefly described, with focus on Rocio virus, Zika virus, Epstein-Barr virus, and Rhinovirus. Finally, the potential influence of CCR5 on the immune responses to coronaviruses is discussed.

Metabolomics as an Approach to Characterise the Contrasting Roles of CCR5 in the Presence and Absence of Disease

Chemokine receptors such as C-C chemokine receptor 5 (CCR5) are activated through interaction with their ligands and are well known for their role in chemotaxis and signal transduction. While serving these roles, cellular responses are effected, hence the immune function of these molecules is established. Given the role of CCR5 in immune function and that the immune and metabolic systems are interlinked, subsequent immune-directed changes should be measurable at a metabolic level. Numerous investigations have reported on metabolic changes associated with CCR5 status in the presence of disease, so as to understand whether specific CCR5 genotypes, frequency and/or levels offer protection to the host or not. However, these metabolic changes were recorded using older conventional techniques. Depending on certain factors such as the disease model, the geography of the samples and/or the ethnic group under study, the role of CCR5 in disease differs. In addition, little is known about CCR5's role in the absence of an enhanced inflammatory state, such as when infection persists. Metabolomics is defined as the study of metabolites and informs on metabolic changes within living organisms as induced by various stimuli, such as the interaction of CCR5 with its ligand. Since metabolomics reflects the underlying biochemical activity and state of cells/tissues, this review proposes it as a tool to clarify the contrasting roles of CCR5.

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.

Transcriptional Signatures of Sleep Duration Discordance in Monozygotic Twins

Introduction

Habitual short sleep duration is associated with adverse metabolic, cardiovascular, and inflammatory effects. Co-twin study methodologies account for familial (eg, genetics and shared environmental) confounding, allowing assessment of subtle environmental effects, such as the effect of habitual short sleep duration on gene expression. Therefore, we investigated gene expression in monozygotic twins discordant for actigraphically phenotyped habitual sleep duration.

Methods

Eleven healthy monozygotic twin pairs (82% female; mean age 42.7 years; SD = 18.1), selected based on subjective sleep duration discordance, were objectively phenotyped for habitual sleep duration with 2 weeks of wrist actigraphy. Peripheral blood leukocyte (PBL) RNA from fasting blood samples was obtained on the final day of actigraphic measurement and hybridized to Illumina humanHT-12 microarrays. Differential gene expression was determined between paired samples and mapped to functional categories using Gene Ontology. Finally, a more comprehensive gene set enrichment analysis was performed based on the entire PBL transcriptome.

Results

The mean 24-hour sleep duration of the total sample was 439.2 minutes (SD = 46.8 minutes; range 325.4-521.6 minutes). Mean within-pair sleep duration difference per 24 hours was 64.4 minutes (SD = 21.2; range 45.9-114.6 minutes). The twin cohort displayed distinctive pathway enrichment based on sleep duration differences. Habitual short sleep was associated with up-regulation of genes involved in transcription, ribosome, translation, and oxidative phosphorylation. Unexpectedly, genes down-regulated in short sleep twins were highly enriched in immuno-inflammatory pathways such as interleukin signaling and leukocyte activation, as well as developmental programs, coagulation cascade, and cell adhesion.

Conclusions

Objectively assessed habitual sleep duration in monozygotic twin pairs appears to be associated with distinct patterns of differential gene expression and pathway enrichment. By accounting for familial confounding and measuring real life sleep duration, our study shows the transcriptomic effects of habitual short sleep on dysregulated immune response and provides a potential link between sleep deprivation and adverse metabolic, cardiovascular, and inflammatory outcomes.

miRNA signatures can predict acute liver failure in hepatitis E infected pregnant females

Background

Acute viral hepatitis E (AVH-E) can often result in acute liver failure (ALF) during pregnancy. microRNAs serve as mediators in drug induced liver failure. We investigated their role as a biomarker in predicting ALF due to HEV (ALF-E).

Methods

We performed next generation sequencing and subsequent validation studies in PBMCs of pregnant (P) self limiting AVH-E, ALF due to HEV (ALF-E) and compared with AVH-E in non-pregnant (NP) females and healthy controls.

Findings

Eleven microRNAs were significantly expressed in response to HEV infection; importantly, miR- 431, 654, 1468 and 4435, were distinctly expressed in pregnant self-limiting AVH-E and healthy females (p = 0.0005), but not in ALF-E. Sixteen exclusive microRNAs differentiated ALF-E from self limiting AVH-E in pregnant females. miR-450b which affects cellular proliferation and metabolic processes through RNF20 and SECB was predominanlty upregulated and correlated with poor outcome (ROC 0.958, p = 0.001).

Interpretation

Our results reveal that a specific microRNA profile can predict fatality in ALF-E in pregnancy. These microRNAs could be exploited as prognostic biomarkers and help in the development of new therapeutic interventions.

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.

An intrahepatic transcriptional signature of enhanced immune activity predicts response to peginterferon in chronic hepatitis B

BACKGROUND & AIMS

Differences in intrahepatic gene expression patterns may be associated with therapy response in peginterferon-treated chronic hepatitis B (CHB) patients.

METHODS

We employed gene expression profiling in baseline liver biopsies of 40 CHB patients (19 HBeAg-positive; 21 HBeAg-negative) treated with peginterferon and adefovir for 48 weeks, and compared expression patterns of combined responders (HBeAg loss, HBV-DNA <2000 IU/ml, alanine aminotransferase normalization after 1 year of treatment-free follow-up) with non-responders. Genes identified by transcriptome analysis in 15 biopsies were confirmed in 25 additional biopsies by RT-qPCR.

RESULTS

Transcriptome analysis demonstrated significant differences in expression of 41 genes between responders and non-responders. In responders, pathway analysis showed specific upregulation of genes related to the immune response, including chemotaxis and antigen processing and presentation. Genes upregulated in responders exhibited strongest similarity with a set of genes induced in livers of chimpanzees with acute Hepatitis B infection. Differential expression was confirmed for eight selected genes. A 2-gene subset (HLA-DPB1, SERPIN-E1) was found to predict response most accurately. Incorporation of these genes in a multivariable model with HBeAg status, HBV genotype and baseline HBsAg level correctly classified 90% of all patients, in which HLA-DPB1 and SERPIN-E1 were independent predictors of response.

CONCLUSION

We identified an intrahepatic transcriptional signature associated with enhanced immune activation which predicts therapy response. These novel associations could lead to better understanding of responsiveness to peginterferon in CHB patients, and may assist in selecting possible responders to interferon-based treatment.

Association between TNFAIP3 nonsynonymous single-nucleotide polymorphism rs2230926 and chronic hepatitis B virus infection in a Chinese Han population

BACKGROUND

Single-nucleotide polymorphisms (SNPs) in tumor necrosis factor alpha-inducible protein 3 (TNFAIP3) gene have been linked to inflammatory, immunological and malignant diseases. Hepatitis B virus (HBV) infection is characterized by immunopathogenesis. This study investigated the association of rs2230926, a nonsynonymous SNP in TNFAIP3 gene, with chronic HBV infection.

METHODS

Four hundred and fifty-five patients with chronic HBV infection with clinical diseases of chronic hepatitis (n = 183), liver cirrhosis (n = 167) and hepatocellular carcinoma (n = 105), 92 HBV infection resolvers and 171 healthy controls were included. All subjects were of Chinese Han ethnicity. Genotyping of rs2230926 was carried out by polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

The gender and age between HBV patients, HBV infection resolvers and healthy controls had no statistical difference. The genotypes of rs2230926 in HBV patients, HBV infection resolvers and healthy controls are in Hardy-Weinberg equilibrium. The genotype and allele frequencies of TNFAIP3 rs2230926 polymorphism between HBV patients, HBV infection resolvers and healthy controls had no significant difference. The genotype and allele frequencies of TNFAIP3 rs2230926 polymorphism between HBV patients with chronic hepatitis, liver cirrhosis and hepatocellular carcinoma also showed no significant difference.

CONCLUSIONS

The TNFAIP3 rs2230926 polymorphism is not suggested to be associated with the susceptibility of chronic HBV infection or the progression of HBV-related diseases in this study. Replicative studies and studies in large control and HBV patient populations of different ethnicity by genotyping more polymorphisms in TNFAIP3 gene are needed.

Regulation of T cell proliferation by JMJD6 and PDGF-BB during chronic hepatitis B infection

T cell functional exhaustion during chronic hepatitis B virus (HBV) infection may contribute to the failed viral clearance; however, the underlying molecular mechanisms remain largely unknown. Here we demonstrate that jumonji domain-containing protein 6 (JMJD6) is a potential regulator of T cell proliferation during chronic HBV infection. The expression of JMJD6 was reduced in T lymphocytes in chronic hepatitis B (CHB) patients, and this reduction in JMJD6 expression was associated with impaired T cell proliferation. Moreover, silencing JMJD6 expression in primary human T cells impaired T cell proliferation. We found that JMJD6 promotes T cell proliferation by suppressing the mRNA expression of CDKN3. Furthermore, we have identified platelet derived growth factor-BB (PDGF-BB) as a regulator of JMJD6 expression. PDGF-BB downregulates JMJD6 expression and inhibits the proliferation of human primary T cells. Importantly, the expression levels of JMJD6 and PDGF-BB in lymphocytes from CHB patients were correlated with the degree of liver damage and the outcome of chronic HBV infection treatment. Our results demonstrate that PDGF-BB and JMJD6 regulate T cell function during chronic HBV infection and may provide insights for the treatment strategies for CHB patients.

Infected hematopoietic stem cells and with integrated HBV DNA generate defective T cells in chronic HBV infection patients

A weak T-cell response plays a key role in the persistence of hepatitis B virus (HBV) infection. We aimed to confirm that T-cell defects in patients with chronic HBV infection are associated with HBV DNA infection of bone marrow (BM) hematopoietic stem cells (HSCs). Using reverse transcription polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH), we observed the transcription of HBsAg coding genes and confirmed the integration of HBV DNA in CD34(+) BM HSCs from chronic HBV infection patients. T cells were generated by coculturing the HSCs with delta-like ligand 1-expressing OP9 (OP9-DL1) cells. The phenotypes of the T cells were then evaluated by flow cytometric (FACS) analysis on days 14 and 25. The results demonstrated that fewer CD3(+) TCRaβ(+) CD3(+) CD4(+) and CD4(+) CD8(+) T cells were generated from the HSCs of the patients than from the healthy controls, (P < 0.01) but the frequency of CD3(+) D8(+) T cells was not significantly different between the two group (P > 0.05). In contrast, CD4(+) CD25(+) T cells were more in the patient group than in healthy controls (P < 0.01) on both days 14 and 25. There were fewer CD3(+) CD4(+) /CD3(+) CD8(+) cells in the patient group than in the healthy control group on day 25 (P < 0.05). Less proliferation and lower levels of IL-2 and IFN- γ were also observed in the patient group compared with the control group (P < 0.05).These data suggest that HBV DNA infected and integrated into the BM HSCs from patients with chronic HBV infection and that these BM HSCs generated defective T cells.

CCR5 on the NK Cells and its Ligand (RANTES) Expressions are Disrupted in South-Eastern Iranian Patients With Chronic Hepatitis B Infection

Background:

CCR5 is a receptor for CCL3 (MIP-1 α), CCL4 (MIP-1 α) and CCL5 (regulated on activation normal T cell expressed and secreted (RANTES)) and play important roles in recruitment of NK cells to the HBV infected liver.

Objectives:

The main purpose of this study was to investigate the expression levels of CCR5 on the NK cells and also serum levels of RANTES in chronic HBV infected (CHI) patients.

Materials and Methods:

In this descriptive study 63 CHI patients and 96 healthy controls were evaluated regarding CCR5 expression on the NK cells and serum levels of RANTES using flow cytometry and ELISA techniques, respectively. Real-Time PCR technique also was used for HBV-DNA quantification.

Results:

The results revealed that CCR5 expressing NK cells and serum levels of RANTES were decreased significantly in the CHI patients in compare to healthy control.

Conclusions:

Based on the results it can be concluded that NK cells of Iranian CHI patients are unable to express adequate levels of CCR5 and expression levels of RANTES by immune cells also are defected in CHI patients, hence, the migration of NK cells to the infected hepatocytes and HBV eradication from the cells is interrupted.

Association of serum soluble human leukocyte antigen-G levels with chronic hepatitis B virus infection

Human leukocyte antigen-G is involved in immunotolerogenic, inflammatory and carcinogenic process. This study investigated serum soluble HLA-G (sHLA-G) levels in patients with chronic hepatitis B virus (HBV) infection according to the infection phases and clinical diagnoses. The study included 223 patients with chronic HBV infection [phases: 38 immune-tolerant (IT), 83 immune clearance (IC), 30 non/low-replicative (LR) and 72 HBeAg negative hepatitis (ENH); diagnoses: 38 asymptomatic HBV carriers (ASC), 98 chronic hepatitis (CH), 46 cirrhosis (LC) and 41 hepatocellular carcinoma (HCC)], 62 HBV infection resolvers and 66 healthy controls. The sHLA-G levels in patients were elevated compared with resolvers and healthy controls (P < 0.001). According to phases, sHLA-G levels were higher in IC and ENH than in IT (P = 0.017 and P = 0.001, respectively). Serum sHLA-G levels were also higher in ENH than in LR (P = 0.008). According to diagnoses, sHLA-G levels in HCC were significantly increased compared with LC, CH and ASC (P = 0.010, P < 0.001 and P < 0.001, respectively). Serum sHLA-G levels were higher in CH than in ASC (P = 0.039). The sHLA-G levels in IC, ENH and CH were correlated with alanine aminotransferase levels (P = 0.011, P = 0.010 and P < 0.001, respectively). It is concluded that sHLA-G is involved in the pathogenesis of chronic HBV infection and correlates with infection phases and clinical diseases, suggesting the value in evaluating disease activity and defining clinical diagnosis.

CCR5 plays important roles in hepatitis B infection

In humans, hepatitis B virus (HBV) is the most prevalent and the main infectious agent that leads to liver disease. Previous investigations identified that long-term HBV-infected patients are unable to eradicate HBV completely from hepatocytes. The main mechanisms responsible for long-term forms of the infections are yet to be clarified. However, researchers believe that the differences in genetic and immunological parameters in the patients in comparison to subjects who successfully clear HBV infections may be the causes for long-term infection. Previous studies demonstrated that chemokines play important roles in the regulation of immune cell migration and activation, which is crucial for a comprehensive immune response against HBV. RANTES, MIP-1α, and MIP-1β are important CC chemokines which act through CC chemokines receptor 5 (CCR5). This receptor is expressed on several effector immune cells including NK cells, T lymphocytes, and macrophages, and plays a crucial role in the regulation of activation and migration of the immune cells during immune responses against viruses, including HBV. Therefore, alterations in its expression or functions could be associated with attenuated immune responses against HBV. In addition, previous studies identified that a 32 base pair deletion (Δ32) in exon 1, as well as three polymorphisms in the promoter region of the CCR5 gene results in downregulation of the molecule. Previous studies revealed that CCR5 expression was altered in hepatitis B but the role of the CCR5 Δ32 mutation and CCR5 promoter polymorphisms in this disease is controversial. This review addresses the recent information regarding the status of CCR5 expression on immune cells and the association of CCR5 promoter polymorphisms with HBV-infected patients.

Increased regulatory T cells and impaired functions of circulating CD8 T lymphocytes is associated with viral persistence in Hepatitis B virus-positive newborns

Hepatitis B Virus (HBV) infection in infancy or early childhood leads to high rate of persistent infection (25-90%). The immunological basis of high rate of viral persistence in vertically acquired HBV infections is not completely understood. CD8 T cells play a pivotal role in clearing the Hepatitis B virus infection in adults. Herein, we sought to delineate the role of T cells in viral persistence in HBsAg+ve newborns. At birth peripheral and cord blood of HBsAg+ve (N = 12), HBsAg-ve (N = 10) and healthy newborns (HC: N = 15) were evaluated for T-cell frequency and functionality by flow cytometry. No significant differences were observed in the frequency of CD8 and CD4 T cells in all the three groups. However, significantly higher frequency of FoxP3 expressing regulatory T cells were observed in HBsAg+ve (63.79%) compared with HBsAg-ve (28.12%) and HC (11.06%) (P < 0.05). Moreover, HBsAg+ve newborns showed functional defect in CD8 T cells by decreased IFN-γ production and lower CD107A expression (cytotoxic capacity) compared with HBsAg-ve and HC, which positively correlated with decreased TCRζ-chain expression CD8 T cells (r(2) > 0.93, P < 0.05). Despite equal frequency of CD8 T cells in all the three groups, CD8 T cells in HBsAg+ve newborns are dysfunctional. An expansion of regulatory T cells and impaired TCR signalling may represent the immune tolerant state of the adaptive immune system in response to chronic HBV infection.

Downregulation of CCR5 expression on the peripheral blood CD8+ T cells of southeastern Iranian patients with chronic hepatitis B infection

Studies indicated that CC receptor 5 (CCR5), as a receptor for CC ligand 3, CCL4, and CCL5, plays important roles in the recruitment of T cytotoxic lymphocytes to the liver of chronic HBV (CHB)-infected patients. The main purpose of this study was to investigate the expression levels of CCR5 on the CD8(+) T lymphocytes of CHB patients. This clinical study was performed on 63 CHB patients and 96 healthy controls. Flow cytometric analysis was performed to examine the expression of CCR5 on CD8(+) T cells of CHB patients. Real-time PCR was also used for HBV-DNA quantification. The results of our study demonstrated that CCR5 expressing T cytotoxic cells were decreased significantly in CHB patients in comparison to healthy control. Based on our results, it can be concluded that the percent of CCR5(+)/CD8(+) T cells in Iranian CHB patients is significantly decreased, hence their migration to the infected liver, and HBV eradication from the hepatocytes is disrupted.

Hepatitis B virus induces IL-23 production in antigen presenting cells and causes liver damage via the IL-23/IL-17 axis

IL-23 regulates myriad processes in the innate and adaptive immune systems, and is a critical mediator of the proinflammatory effects exerted by Th17 cells in many diseases. In this study, we investigated whether and how hepatitis B virus (HBV) causes liver damage directly through the IL-23 signaling pathway. In biopsied liver tissues from HBV-infected patients, expression of both IL-23 and IL-23R was remarkably elevated. In vivo observations also indicated that the main sources of IL-23 were myeloid dendritic cells (mDCs) and macrophages. Analysis of in vitro differentiated immature DCs and macrophages isolated from healthy donors revealed that the HBV surface antigen (HBsAg) efficiently induces IL-23 secretion in a mannose receptor (MR)-dependent manner. Culture with an endosomal acidification inhibitor and the dynamin inhibitor showed that, upon binding to the MR, the HBsAg is taken up by mDCs and macrophages through an endocytosis mechanism. In contrast, although the HBV core antigen (HBcAg) can also stimulate IL-23 secretion from mDCs, the process was MR- and endocytosis-independent. In addition, IL-23 was shown to be indispensible for HBsAg-stimulated differentiation of naïve CD4(+) T cells into Th17 cells, which were determined to be the primary source of IL-17 in HBV-infected livers. The cognate receptor, IL-17R, was found to exist on the hepatic stellate cells and mDCs, both of which might represent the potential target cells of IL-17 in hepatitis B disease. These data provide novel insights into a yet unrecognized mechanism of HBV-induced hepatitis, by which increases in IL-23 expression, through an MR/endocytosis-dependent or -independent manner, produce liver damage through the IL-23/IL-17 axis.

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.

Management of acute hepatitis B and reactivation of hepatitis B

The natural course of hepatitis B virus infection and the resulting hepatic injury is determined by the degree of virus replication and the intensity of host immune response. Upon exposure to hepatitis B virus (HBV), individuals with a vigorous and broad immune response develop acute self-limited infection, which may result in acute hepatitis. However, with stringent testing for HBV and universal precautions, acute HBV is rather rare. Reactivation of HBV most often presents as acute hepatitis B (AVH-B) and clinically, it is difficult to differentiate AVH-B from reactivation of chronic hepatitis B (CHB) and it requires a high index of suspicion. In the presence of high HBV DNA (>2 × 10(4) IU/ml) underlying liver disease should be investigated by liver biopsy, endoscopy and/or imaging. The degree of liver failure often depends on the severity of acute insult and the stage of underlying chronic liver disease. Mutations in the HBV genome, immunosuppressive therapy and viral or drug induced injury are common causes of reactivation. As most patients with AVH-B resolve the infection spontaneously, antiviral therapy is not indicated in them. However, the use of a potent oral nucleoside(tide) analogue is necessary as soon as possible in patients with CHB reactivation. Liver transplantation should be considered in patients who develop liver failure secondary to severe acute exacerbation. If this is not feasible, supportive therapy with the addition of granulocyte colony stimulating factor (GCSF) therapy could be beneficial.

Analysis of Notch and TGF-β Signaling Expression in Different Stages of Disease Progression During Hepatitis B Virus Infection

OBJECTIVES:

CD4+ regulatory T cells (Tregs) seem to have a key role in persistence of hepatitis B virus (HBV) infection. Notch and transforming growth factor (TGF-β) signaling independently help in the differentiation and regulation of CD4+T cells, including T-helper (T_H) 1, T_H2, and Tregs. Whether, the two pathways have modulatory role on different stages of HBV infection and severity of liver disease is not clear. We investigated Notch and TGF-β families' gene expression in peripheral blood and intrahepatic lymphocytes in patients with different stages of chronic HBV (CHB) infection.

METHODS:

Peripheral blood mononuclear cells (PBMCs), CD4⁺, and CD8⁺ T cells were isolated from patients with acute HBV (AVH-B, n=15), CHB (n=16), and controls (HC, n=10). In addition to PBMCs, intrahepatic lymphocytes were obtained from liver biopsies from CHB (n=12), cirrhosis (n=12), hepatocellular carcinoma (HCC, n=5), and healthy livers (n=5). Notch family (Notch1–4, Hes1, Jag1, and NF-kβ) and TGF-β family gene expressions were studied by real-time PCR, flow cytometry, and immunohistochemistry.

RESULTS:

Relative expression of Notch signaling target genes, Hes1 and NF-kβ, was higher in the total PBMCs of AVH-B and CHB patients than that in HC patients (Log relative quantification (RQ); 1.1 AVH-B vs. 0.3 HC, 1.3 CHB vs. 0.3 HC; P=0.02). CD8⁺ T cells showed upregulated expression of Hes1 and Notch1 (P=0.02 and 0.01, respectively) in AVH-B than in CHB patients. Also, in AVH-B patients, HBV-specific CD8⁺ T-cell proliferation (5.74% vs. 2.7%) and TGF-β signaling activity were higher. All Notch receptors and ligands were upregulated in the PBMCs in CHB infection (CHB vs. cirrhosis, P=0.001; CHB vs. HCC, P=0.023; and cirrhosis vs. HCC, P=NS). Intrahepatic expression of Notch1 and FoxP3 were significantly higher in cirrhotics and HCCs, and further blockage of Notch signaling reduced the FoxP3 expression. Array data of TGF-β family showed increased TGF-β3, TGF-α, SMAD3, SMAD4, SMAD6, and GDF9 expression on intrahepatic lymphocytes in cirrhotic and HCC patients compared with CHB.

CONCLUSIONS:

Our findings suggest that there is a complementary association between Notch1 and Hes1 in CD8⁺T cells during AVH-B infection. On development of CHB infection, repression of the Notch receptors mediates the regulation of immune response in patients, who progress to cirrhosis and HCC. Finally, HBV infection drives increased Notch1, TGF-β, and FoxP3 expression on intrahepatic T cells in cirrhosis, resulting in fibrogenesis and disease progression.

Pivotal roles of the interleukin-23/T helper 17 cell axis in hepatitis B

T helper 17 (Th17) cells are a newly identified subset of T helper cells that play important roles in host defense against extracellular bacteria, as well as in the pathogenesis of autoimmune disease. Research interest in these cells was piqued when hepatitis B virus (HBV)-infected patients were found to have significantly elevated Th17 cell frequency, and it was proposed that these proinflammatory effectors may promote the HBV disease process. Subsequent studies have revealed that Th17 cells drive immune-mediated pathology of HBV infection, and that IL-23 amplifies the Th17 cell responses and liver inflammation. As a result, new pathways of HBV-mediated liver damage have been elucidated, along with promising new targets of molecular therapeutic strategies. Ongoing research is also providing significant insights into the target cells and underlying mechanisms of Th17-secreted cytokines, including IL-17A, IL-21 and IL-22. Future studies are expected to fully uncover the cytokine-related mechanisms mediating HBV-induced liver inflammation, and to determine the yet unknown cell source of IL-23. This review will draw upon the most up-to-date available data to discuss the putative roles and detailed mechanisms of IL-23/Th17 cell axis in HBV infection-mediated liver pathogenesis.

Aberrant production of soluble co-stimulatory molecules CTLA-4 and CD28 in patients with chronic hepatitis B

Co-stimulation signals are critical for anti-viral immunity. Here we investigated whether there is altered expression and the clinical significance of soluble co-stimulatory molecules in patients with chronic HBV infection. Serum concentrations and ex vivo production of soluble CTLA-4, CD28, CD80 and CD86 were analyzed by enzyme-linked immunosorbent assay. Serum sCTLA-4 and sCD28 concentrations in all chronic HBV patients were significantly higher than concentrations in healthy control subjects. Serum sCTLA-4 and sCD28 correlated significantly with alanine aminotransferase in all chronic HBV patients. Upon mitogen stimulation of peripheral blood mononuclear cells, the percentage increases in ex vivo production of sCD28 and sCD80 and the percentage decrease in sCTLA-4 release were all significantly lower in chronic HBV patients than those in healthy subjects. The aberrant production of soluble co-stimulatory molecules should reflect the dysregulation of T cell activation and is related to the pathogenesis and severity of chronic HBV infection.

Circulating Tregs correlate with viral load reduction in chronic HBV-treated patients with tenofovir disoproxil fumarate

Limited response to current hepatitis B virus (HBV) drugs is possibly due to inadequate host cytotoxic cellular responses. Circulating Tregs have been shown to be associated with chronicity of HBV infection, but their profile during antiviral therapy has not been studied. We analyzed the frequency and effect of Tregs on cellular immune responses against HBV in 35 chronic hepatitis B eAg-ve and eAg+ve patients treated with tenofovir 300 mg/day. Frequency of Tregs and their modulatory role in cytokine-secreting cells were determined after stimulation with HBsAg or HBcAg in the absence or presence of Tregs and after blockage of PD-1/PDL-1 in peripheral blood mononuclear cells (PBMCs). Prior to therapy, eAg-ve patients had lower HBV DNA levels, reduced CD8 T cells, increased Tregs, and T cells expressing PD1. After 12 weeks of therapy, >2 log HBV viral reduction was observed in both groups, along with an increase frequencies of CD8 T cells in eAg-ve patients and increased expression of chemokine receptors/Toll-like receptors in both groups. PD-1 expression on CD8 cells in PBMCs was decreased in both groups during therapy but not on Tregs. In eAg-ve group, sustained increase of Tregs was observed till week 12, which declined at week 24. In both groups, after 24 weeks, depletion of CD4(+)CD25(+) Tregs from PBMCs enhanced HBV-specific T cell responses, and blockage of PD-1/PDL1 pathway did enhance pro-inflammatory cytokine production in eAg+ve patients but not in eAg-ve. We conclude that Tregs induced by HBV replication in vivo are expanded in eAg-ve patients more. Reduction in HBV DNA by tenofovir partially restored adaptive immune responses and also reduced the Tregs. Blockage of PD-1/PDL1, enhanced cytokine production in eAg+ve patients but not in eAg-ve, suggests that distinctly different immunologic mechanisms are involved in eAg+ve and eAg-ve patients.

A gene expression signature for insulin resistance

Insulin resistance is a heterogeneous disorder caused by a range of genetic and environmental factors, and we hypothesize that its etiology varies considerably between individuals. This heterogeneity provides significant challenges to the development of effective therapeutic regimes for long-term management of type 2 diabetes. We describe a novel strategy, using large-scale gene expression profiling, to develop a gene expression signature (GES) that reflects the overall state of insulin resistance in cells and patients. The GES was developed from 3T3-L1 adipocytes that were made “insulin resistant” by treatment with tumor necrosis factor-α (TNF-α) and then reversed with aspirin and troglitazone (“resensitized”). The GES consisted of five genes whose expression levels best discriminated between the insulin-resistant and insulin-resensitized states. We then used this GES to screen a compound library for agents that affected the GES genes in 3T3-L1 adipocytes in a way that most closely resembled the changes seen when insulin resistance was successfully reversed with aspirin and troglitazone. This screen identified both known and new insulin-sensitizing compounds including nonsteroidal anti-inflammatory agents, β-adrenergic antagonists, β-lactams, and sodium channel blockers. We tested the biological relevance of this GES in participants in the San Antonio Family Heart Study ( n = 1,240) and showed that patients with the lowest GES scores were more insulin resistant (according to HOMA_IR and fasting plasma insulin levels; P < 0.001). These findings show that GES technology can be used for both the discovery of insulin-sensitizing compounds and the characterization of patients into subtypes of insulin resistance according to GES scores, opening the possibility of developing a personalized medicine approach to type 2 diabetes.

Acute liver failure: mechanisms of immune-mediated liver injury

Acute liver failure (ALF) is a syndrome of diverse aetiology, including hepatic encephalopathy, renal, cardiac and pulmonary failures, which result in a rapid loss of hepatic function. The mechanisms of liver injury contributing to ALF can be summarized into two categories: direct damage and immune-mediated liver injury. This review summarizes current concepts of immune-mediated liver injury from both clinical studies and animal models. We highlight immune responses of ALF from the liver injury perspective, which combines a variety of molecular and cellular mechanisms, particularly, the contribution of cytokines and the innate immune system. Hepatic and circulating inflammatory cytokines play a significant role in the pathophysiology of ALF including hepatocyte necrosis, extrahepatic complications and hepatocyte regeneration. Overproduction of cytokines, if unchecked, is hazardous to the host and may cause severe outcomes. Measuring pro-inflammatory cytokines in ALF may be of value for predictors of outcome. Innate and adaptive immune systems both involved in ALF contribute to immune-mediated liver injury. The innate immune response is activated much more rapidly compared with adaptive immunity, particularly in acute liver injury where the host has little time to trigger an effective adaptive immune response. From this point of view, the innate immune system may make a more profound contribution than the adaptive immune system. Furthermore, immune responses crosstalk with other physiological or pathophysiological factors, for example, coagulation factors which in turn determine the outcome of ALF and these are discussed.

Th17 cells and their associated cytokines in liver diseases

T helper 17 (Th17) cells are a newly identified subset of T helper cells that play important roles in host defense against extracellular bacteria as well as in the pathogenesis of autoimmune disease. The functions of Th17 cells are mediated via the production of several cytokines including interleukin (IL)-17 and IL-22. Recent studies show that the frequency of IL-17(+) cells is significantly elevated in a variety of chronic liver diseases including alcoholic liver disease, viral hepatitis and hepatocellular carcinoma. IL-17 receptor is expressed virtually on all types of liver cells, while IL-22 receptor expression is restricted to epithelial cells including hepatocytes in the liver. IL-17 seems to play an important role in inducing liver inflammation via stimulating multiple types of liver nonparenchymal cells to produce proinflammatory cytokines and chemokines, while IL-22 appears to be an important factor in promoting hepatocyte survival and proliferation.

Genome-wide identification of human FOXP3 target genes in natural regulatory T cells

The transcription factor FOXP3 is essential for the formation and function of regulatory T cells (Tregs), and Tregs are essential for maintaining immune homeostasis and tolerance. This is demonstrated by a lethal autoimmune defect in mice lacking Foxp3 and in immunodysregulation polyendocrinopathy enteropathy X-linked syndrome patients. However, little is known about the molecular basis of human FOXP3 function or the relationship between direct and indirect targets of FOXP3 in human Tregs. To investigate this, we have performed a comprehensive genome-wide analysis for human FOXP3 target genes from cord blood Tregs using chromatin immunoprecipitation array profiling and expression profiling. We have identified 5579 human FOXP3 target genes and derived a core Treg gene signature conserved across species using mouse chromatin immunoprecipitation data sets. A total of 739 of the 5579 FOXP3 target genes were differentially regulated in Tregs compared with Th cells, thus allowing the identification of a number of pathways and biological functions overrepresented in Tregs. We have identified gene families including cell surface molecules and microRNAs that are differentially expressed in FOXP3(+) Tregs. In particular, we have identified a novel role for peptidase inhibitor 16, which is expressed on the cell surface of >80% of resting human CD25(+)FOXP3(+) Tregs, suggesting that in conjunction with CD25 peptidase inhibitor 16 may be a surrogate surface marker for Tregs with potential clinical application.