Increased Th17 cells and interleukin-17 contribute to immune activation and disease aggravation in patients with chronic hepatitis B virus infection

AhR may be involved in Th17 cell differentiation in chronic hepatitis B

Th17 cells which are crucial for host immunity have been demonstrated to increase HBV infection. However, the mechanism of the Th17 cell increase is unknown. Hence, the mechanism of Th17 cell enhancement is important to provide a theoretical foundation for chronic hepatitis B immunotherapy. This study included 15 instances in the healthy control (HC) and 15 cohorts in the chronic hepatitis B (CHB). Their CD4+ T cells were isolated from their peripheral blood and then subjected to RNA transcriptome sequencing. Then, to identify target genes linked to Th17-cell differentiation, DEGs associated with CHB were convergent with the Th17-cell-associated genes from the KEGG database. Hub genes of DEG and target genes linked to Th17 cells were analysed for correlation. The AhR-related genes were located using the GeneMANIA database. To analyse the function of the genes, GO and KEGG pathways were employed. Protein-protein interaction network analysis employed the Metascape, STRING and Cytoscape databases. Finally, Western blotting and RT-qPCR were used to validate AhR. A total of 348 differential genes were identified in CHB patients. CytoHubba was used for screening five hub genes associated with CHB: CXCL10, RACGAP1, TPX2, FN1 and GZMA. This study aimed to determine the mechanism of elevated Th17 cells in CHB. As a result, further investigation using the convergence of DGEs and Th17 cell-related genes identified three target genes: AhR, HLA-DQA1 and HLA-DQB1, all of which were elevated in CHB. The three genes were primarily involved in immune response-related processes, according to the GO enrichment analysis. Correlation analysis of CXCL10, RACGAP1, TPX2, FN1 and GZMA genes with AhR, HLA-DQA1 and HLA-DQB1 revealed that AhR was positively associated with CXCL10 and GZMA genes, which best respond to the severity of CHB disease. Combined with the role of AhR in Th17 cell differentiation, the genes AhR was chosen for confirmation by RT-qPCR and WB in this study. The results showed that the CHB group had higher expression levels of AhR at both RT-qPCR and WB levels. Furthermore, this study's findings revealed that AhR may contribute to the development of CHB by affecting the differentiation of Th17 cells.

The Role of Interleukins in HBV Infection: A Narrative Review

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

Aberrant cytokine and VCAM-1 expression in patients with viral and non-viral related liver cirrhosis

The study aim was to compare the alterations in the expression levels of proinflammatory and chemotactic cytokines as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-17A and IL-8, the down regulatory cytokine IL-10, in addition to the vascular cell adhesion molecule-1 (VCAM-1) gene in different groups of patients with cirrhosis due to various etiologies. This case-control study included 84 patients suffering from cirrhosis of viral and non-viral etiologies and 20 sex and age-matched healthy controls. All patients were subjected to detailed history taking, clinical examination, and liver function assessment. The expression levels of TNF-α, IL-17A, IL-8, IL-10, and VCAM-1 were assessed in peripheral blood mononuclear cells by real-time PCR. Patients with cirrhosis showed marked changes in the tested gene expression levels relative to the control group. Higher expression levels of all genes except IL-10 were seen in patients of the viral than in the non-viral groups. Most of the significant correlations of liver function parameters were observed with TNF-α in both the viral and non-viral groups, followed by IL-17A. Increased TNF-α and IL-17A presented potential risk factors for disease progression to cirrhosis of Child class C.

Microbial Components and Effector Molecules in T Helper Cell Differentiation and Function

The mammalian intestines harbor trillions of commensal microorganisms composed of thousands of species that are collectively called gut microbiota. Among the microbiota, bacteria are the predominant microorganism, with viruses, protozoa, and fungi (mycobiota) making up a relatively smaller population. The microbial communities play fundamental roles in the maturation and orchestration of the immune landscape in health and disease. Primarily, the gut microbiota modulates the immune system to maintain homeostasis and plays a crucial role in regulating the pathogenesis and pathophysiology of inflammatory, neuronal, and metabolic disorders. The microbiota modulates the host immune system through direct interactions with immune cells or indirect mechanisms such as producing short-chain acids and diverse metabolites. Numerous researchers have put extensive efforts into investigating the role of microbes in immune regulation, discovering novel immunomodulatory microbial species, identifying key effector molecules, and demonstrating how microbes and their key effector molecules mechanistically impact the host immune system. Consequently, recent studies suggest that several microbial species and their immunomodulatory molecules have therapeutic applicability in preclinical settings of multiple disorders. Nonetheless, it is still unclear why and how a handful of microorganisms and their key molecules affect the host immunity in diverse diseases. This review mainly discusses the role of microbes and their metabolites in T helper cell differentiation, immunomodulatory function, and their modes of action.

Serum Interleukins as Potential Prognostic Biomarkers in HBV-Related Acute-on-Chronic Liver Failure

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is relatively common in China and has complex pathogenesis, difficult clinical treatment, and poor prognosis. Immune status is an important factor affecting ACLF prognosis. Interleukins are a family of secreted lymphocyte factors that interact with a host of cell types including immune cells. These signaling molecules play important roles in transmitting information; regulating immune cells; mediating the activation, proliferation, and differentiation of T and B cells; and modulating inflammatory responses. Many studies have investigated the correlation between interleukin expression and the prognosis of HBV-ACLF. This review focuses on the potential use of interleukins as prognostic biomarkers in HBV-ACLF. References were mainly identified through PubMed and CNKI search, including relevant studies published until December 2021. We have summarized reports of several promising diagnostic interleukin biomarkers that predict susceptibility to HBV-ACLF. The use of biomarkers to understand early prognosis can help devise different therapeutic measures and improve patient survival. Ongoing research on prognostic biomarkers of HBV-ACLF is promising, and future preclinical and clinical studies are warranted.

Circulating IL-1β, IL-17, and IP-10 as Potential Predictors of Hepatitis B Virus Infection Prognosis

Circulating cytokines and chemokines play critical roles in hepatitis B virus (HBV) infection. Here, we explored the effects of proinflammatory and anti-inflammatory effector molecules on HBV progression, e antigen seroconversion, and liver function. Our results showed that circulating interleukin (IL)-17 may be helpful in HBV spontaneous clearance [odds ratio (OR) = 1.468, 95%confidence interval (CI) = 1.080–1.995, P = 0.014] and protective against HBV-related hepatoma development (OR = 0.933, 95%CI = 0.910–0.957, P < 0.001). IL-1β negatively affected HBV clearance (OR = 0.052, 95%CI = 0.005–0.534, P = 0.013). In patients with chronic hepatitis B, interferon-γ-inducible protein-10 (IP-10) levels significantly increased in the group of abnormal liver function (P = 0.006). Furthermore, positive correlations of IP-10 with alanine aminotransferase and aspartate aminotransferase levels were observed (r_s = 0.546 and 0.644, respectively; P < 0.001). In conclusion, inflammatory cytokines and chemokines may be a “double-edged sword” for HBV clearance and progression. Further exploration of the roles of IL-17, IL-1β, and IP-10 in chronic HBV infection is needed.

Hepatitis Virus Reactivation in Patients with Psoriasis Treated with Secukinumab in a Real-World Setting of Hepatitis B or Hepatitis C Infection

BACKGROUND AND OBJECTIVE

Biologics for psoriasis, especially anti-tumor necrosis factor-α therapies, may reactivate hepatitis B virus (HBV) or hepatitis C virus (HCV) infections, as well in inactive carriers or patients with occult infection. However, some biologics, including anti-interleukin-17 therapies such as secukinumab, seem to be less likely to cause hepatitis reactivation. This study assessed the safety of secukinumab treatment in patients with psoriasis with HBV or HBC infection.

METHODS

This was a retrospective cohort study of patients with moderate-to-severe psoriasis treated with secukinumab at seven Italian centers. Patients serologically positive for one or more of the following viral hepatitis markers were included: HCV antibody (± HCV-RNA positivity) and/or hepatitis B surface antigen, and/or HBV core antibody and/or HBV surface antibody (± HBV-DNA positivity). Patients received secukinumab 300 mg subcutaneously at week 0/1/2/3/4 then every 4 weeks; prophylactic therapy before starting secukinumab was prescribed where indicated. The primary study endpoint was the reactivation of hepatitis viral infection, defined as conversion to HBV-DNA or HCV-RNA positivity, with or without elevation of transaminases.

RESULTS

Sixty patients (17 with concomitant psoriatic arthritis) were included. Thirteen subjects were hepatitis B surface antigen positive, 19 were HBV core antibody positive, and 30 were positive for the HCV antibody; however, all were HCV-RNA negative. After 53.5 ± 37.5 weeks of secukinumab therapy, hepatitis reactivation occurred in only one patient, who had a reactivation of both hepatitis B and hepatitis C. This patient had not undergone hepatitis B prophylaxis or hepatitis C treatment before secukinumab.

CONCLUSIONS

These real-world data support the safety of secukinumab in patients with positive markers of HBV or HCV infection, when administered together with dedicated prophylaxis.

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

Background

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

Methods

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

Results

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

Conclusions

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

Supplementary Information

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

Interleukin-17-A multifaceted cytokine in viral infections

Viral infections are a major threat to the human population due to the lack of selective therapeutic measures. The morbidity and mortality reported worldwide are very alarming against viral pathogens. The proinflammatory environment is required for viral inhibition by initiating the host immune response. The host immune response fights these pathogens by secreting different cytokines. Interleukin-17 (IL-17) a proinflammatory cytokine mainly produced by T helper type 17 cells, plays a vital role in the regulation of host immune response against various pathogens, including viruses. However, dysregulated production of IL-17 induces chronic inflammation, autoimmune disorders, and may lead to cancer. Recent studies suggest that IL-17 is not only involved in the antiviral immune response but also promotes virus-mediated illnesses. In this review, we discuss the protective and pathogenic role of IL-17 against various viral infections. A detailed understanding of IL-17 during viral infections could contribute to improve therapeutic measures and enable the development of an efficient and safe IL-17 based immunotherapy.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Abnormal Innate Immunity in Acute-on-Chronic Liver Failure: Immunotargets for Therapeutics

Acute-on-chronic liver failure (ACLF) is a severe life-threatening condition with high risk of multiorgan failure, sepsis, and mortality. ACLF activates a multifaceted interplay of both innate and adaptive immune response in the host which governs the overall outcome. Innate immune cells recognize the conserved elements of microbial and viral origin, both to extort instant defense by transforming into diverse modules of effector responses and to generate long-lasting immunity but can also trigger a massive intrahepatic immune inflammatory response. Acute insult results in the activation of innate immune cells which provokes cytokine and chemokine cascade and subsequently initiates aggressive systemic inflammatory response syndrome, hepatic damage, and high mortality in ACLF. Dysregulated innate immune response not only plays a critical role in disease progression but also potentially correlates with clinical disease severity indices including Child-Turcotte-Pugh, a model for end-stage liver disease, and sequential organ failure assessment score. A better understanding of the pathophysiological basis of the disease and precise immune mechanisms associated with liver injury offers a novel approach for the development of new and efficient therapies to treat this severely ill entity. Immunotherapies could be helpful in targeting immune-mediated organ damage which may constrain progression toward liver failure and eventually reduce the requirement for liver transplantation. Here, in this review we discuss the defects of different innate immune cells in ACLF which updates the current knowledge of innate immune response and provide potential targets for new therapeutic interventions.

Regulatory T cells and T helper 17 cells in viral infection

CD4⁺ T cells are the central element of the adaptive immune responses and protect the body from a variety of pathogens. Starting from naive cells, CD4⁺ T cells can differentiate into various effector cell subsets with specialized functions including T helper (Th) 1, Th2, Th17, regulatory T (Treg) and T follicular helper (Tfh) cells. Among them, Tregs and Th17 cells show a strong plasticity allowing the functional adaptation to various physiological and pathological environments during immune responses. Although they are derived from the same precursor cells and their differentiation pathways are interrelated, the terminally differentiated cells have totally opposite functions. Studies have shown that Tregs and Th17 cells have rather complex interplays in viral infection: Th17 cells may contribute to immune activation and disease progression while Tregs may inhibit this process and play a key role in the maintenance of immune homoeostasis, possibly at the cost of compromised viral control. In this review, we take respiratory syncytial virus (RSV), hepatitis B virus (HBV)/hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections as examples to discuss these interplays and their impacts on disease progression in viral infection.

Differential Expression of Immune Inhibitory Checkpoint Signatures on Antiviral and Inflammatory T Cell Populations in Chronic Hepatitis B

Virus-specific T cells are critical in mediating the pathogenesis of hepatitis B virus (HBV) infection. Interferon gamma (IFNγ)-producing T cells are associated with resolution; in contrast, interleukin-17 (IL-17)-producing T cells are linked to exacerbation of liver inflammation and injury. Checkpoint receptors stringently regulate T cell functions, with their expression profiles varying on different T cell subsets. Blockade of checkpoint receptors may be an effective therapeutic strategy for chronic hepatitis B (CHB); however, blockade may also inadvertently exacerbate proinflammatory responses. In this study, we sought to determine the balance of inflammatory and antiviral T cells and determine their inhibitory receptor profile. The frequency of total and HBV antigen-specific Th17 and Tc17 cells was higher in CHB patients compared with healthy controls (HCs). Th17 and Tc17 cells in CHB patients had significantly lower expression of T cell immunoglobulin and mucin domain protein-3 (TIM-3) compared with HCs, with no difference in programmed death-1 (PD-1) or CD244 expression. Conversely, Th1 and Tc1 cells in CHB patients hyperexpressed PD-1 and CD244, while TIM-3 expression was comparable in both cohorts. During CHB, antiviral IFNγ T cells hyperexpress multiple immune inhibitory receptors driving their functional impairment. In contrast, inflammatory Th17/Tc17 cells hypoexpress TIM-3, but not PD-1 or CD244. Checkpoint inhibitors for CHB should target PD-1 or CD244 to allow restoration of IFNγ responses without affecting inflammatory IL-17 production.

Soluble immune markers in the different phases of chronic hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection may follow four different consecutive phases, which are defined by virology as well as biochemical markers and differ in terms of prognosis and need for antiviral treatment. Currently, host responses reflected by immune markers are not considered in this definition. We aimed to study soluble immune markers and their distribution in different phases of chronic HBV infection. In this cross-sectional retrospective study, we investigated a panel of 14 soluble immune markers (SIM) including CXCL10 in 333 patients with chronic HBV infection. In a small cohort of HBeAg positive patients we analyzed SIM before and after HBeAg seroconversion and compared seroconverters to patients with unknown outcome. Significant differences were documented in the levels of several SIM between the four phases of chronic HBV infection. The most pronounced difference among all investigated SIM was observed for CXCL10 concentrations with highest levels in patients with hepatitis. TGF-β and IL-17 revealed different levels between HBeAg negative patients. HBeAg positive patients with HBeAg seroconversion presented higher amounts of IL-12 before seroconversion compared to HBeAg positive patients with unknown follow up. SIM such as CXCL10 but also IL-12, TGF-β and IL-17 may be useful markers to further characterize the phase of chronic HBV infection.

The protective and pathogenic roles of IL-17 in viral infections: friend or foe?

Viral infections cause substantial human morbidity and mortality, and are a significant health burden worldwide. Following a viral infection, the host may initiate complex antiviral immune responses to antagonize viral invasion and replication. However, proinflammatory antiviral immune responses pose a great threat to the host if not properly held in check. Interleukin (IL)-17 is a pleiotropic cytokine participating in a variety of physiological and pathophysiological conditions, including tissue integrity maintenance, cancer progression, autoimmune disease development and, more intriguingly, infectious diseases. Abundant evidence suggests that while IL-17 plays a crucial role in enhancing effective antiviral immune responses, it may also promote and exacerbate virus-induced illnesses. Accumulated experimental and clinical evidence has broadened our understanding of the seemingly paradoxical role of IL-17 in viral infections and suggests that IL-17-targeted immunotherapy may be a promising therapeutic option. Herein, we summarize current knowledge regarding the protective and pathogenic roles of IL-17 in viral infections, with emphasis on underlying mechanisms. The various and critical roles of IL-17 in viral infections necessitate the development of therapeutic strategies that are uniquely tailored to both the infectious agent and the infection environment.

Expression of IL-17 and its gene promoter methylation status are associated with the progression of chronic hepatitis B virus infection

To explore interleukin-17 (IL-17) and its epigenetic regulation during the progression of chronic hepatitis B virus (HBV) infection.A total of 162 patients with chronic HBV infection, including 75 with chronic hepatitis B (CHB), 54 with hepatitis B-associated liver cirrhosis and 33 with hepatitis B-associated hepatocellular carcinoma (HBV-HCC), were enrolled in this study. Thirty healthy adults of the same ethnicity were enrolled in the control group. Whole venous blood was obtained from the patients and normal controls (n = 30). Clinical and laboratory parameters were assessed, and we performed enzyme-linked immunosorbent assay and quantitative real-time PCR to measure the serum levels and relative mRNA expression of IL-17, respectively. IL-17 promoter methylation in peripheral blood mononuclear cells was assessed by methylation-specific PCR. We analyzed the serum and mRNA levels of IL-17 and IL-17 promoter methylation in the 4 groups as well as the effect of methylation on serum IL-17 levels. Correlations between the IL-17 promoter methylation status and clinical parameters were analyzed by Spearman correlation analysis.Compared to the normal control group, the patient groups exhibited significantly higher serum and relative mRNA levels of IL-17. The methylation distribution among the patients was significantly lower than that among the normal controls (P < .05), with the HBV-HCC group showing the lowest IL-17 gene methylation frequency. The average IL-17 promoter CG methylation level was negatively correlated with IL-17 mRNA expression (r = -0.39, P = .03), and negative correlations between IL-17 promoter methylation and prothrombin time activity (r = -0.585, P = .035), alanine aminotransferase (r = -0.522, P < .01), aspartate aminotransferase (r = -0.315, P < .05), and the model for end-stage liver disease score (r = -0.461, P < .05) were observed. IL-17 serum levels in the methylated-promoter groups were significantly lower than those in the unmethylated-promoter groups.IL-17 expression and promoter methylation were associated with chronic HBV infection progression, especially in the HBV-HCC group. The IL-17 promoter status may help clinicians initiate the correct treatment strategy at the CHB stage.

Increased interleukin-23 receptor (IL-23R) expression is associated with disease severity in acute-on-chronic liver failure

BACKGROUND

Th17 cells mediated immune response is important in chronic hepatitis B (CHB) infection and inflammation associated diseases; however, little is known about their immunopathogenic role in acute-on-chronic liver failure (ACLF). Interleukin-23 receptor (IL-23R) is essential for the generation of pathogenic Th17 cells; therefore, we aimed to evaluate IL-23R expression and its correlation with disease severity in ACLF.

METHODS

Forty-two patients with ACLF (HBV and alcohol-related), thirty-two with CHB and twenty healthy controls (HC) were studied. Circulating and intrahepatic profile of Th17 cells and IL-23R was investigated. Association of IL-23R with disease severity was determined.

RESULTS

Circulating Th17 cells were significantly increased in both ACLF groups (P = 0.03, P = 0.006) than CHB and HC. Percentage of Th17 cells was higher in liver than peripheral blood of ACLF patients (P = 0.04). Expression of IL-23R was immensely up-regulated on Th17 cells of ACLF patients. Importantly, IL-23R not only correlated with the increased percentage of Th17 cells but also had significant association with inflammation (P = 0.03) and clinical disease severity indices including Child-Turcotte-Pugh (P = 0.001) and Model for End-Stage Liver Disease (P = 0.002) scores. The ACLF non-survivors showed higher IL-23R expression (P = 0.01). Transcription factor retinoic acid receptor-related orphan nuclear receptor gamma-t (ROR-γt) was also high in circulation and in liver of ACLF patients and it positively correlated with ALT levels (P = 0.03). Surface receptors, including CCR6, IL-17R and pro-inflammatory cytokines IL-17A, IL-22, CXCL8 and GM-CSF were highly augmented in ACLF.

CONCLUSION

ACLF patients express high IL-23R on Th17 cells which induces inflammation and strongly correlates with liver disease severity.

Elevated interleukin-35 suppresses liver inflammation by regulation of T helper 17 cells in acute hepatitis B virus infection

Interleukin (IL)-35 is a responsive anti-inflammatory cytokine implicated in different diseases processes. It has been reported that elevated IL-35 contributed to immunosuppression in chronic hepatitis by modulation of T helper 17 (Th17) and regulatory T cells. However, the role of IL-35 in acute hepatitis B (AHB) was still not completely elucidated. Thus, in the present study, we analyzed the expression and regulatory activity of IL-35 to Th17 cells and inflammatory response during acute hepatitis B virus (HBV) infection in both peripheral blood cells isolated from AHB patients and in hydrodynamic induced HBV-infected mouse model. Plasma IL-35 level and circulating HBV peptides-induced Th17 frequency was significantly elevated in AHB patients, and IL-35 expression negatively correlated with liver inflammation. In vitro IL-35 stimulation to CD4+ T cells purified from AHB patients down-regulated HBV peptides-induced Th17-phenotype, which presented as reduced IL-17 and IL-22 production. In vivo IL-35 administration dampened liver inflammation in HBV plasmid injected mice, however, did not affect HBV antigens production. This process was accompanied by suppression of natural killer cells and down-regulation of HBV peptides-induced Th17 cells in the liver, but did not affect total intrahepatic lymphocytes and other cell subsets numbers or chemokines expression in the liver. In conclusion, the current data indicated that IL-35 might be a novel mediator associated with hepatocytes damage and liver inflammation by regulating HBV peptides-induced Th17 cells during acute HBV infection. The potential anti-inflammatory property of IL-35 might be pivotal for developing new therapeutic approaches for hepatitis B.

Decreased Frequencies of Th17 and Tc17 Cells in Patients Infected with Avian Influenza A (H7N9) Virus

The outbreak of avian influenza A (H7N9) virus infection, with a high mortality rate, has caused concern worldwide. Although interleukin-17- (IL-17-) secreting CD4⁺ T (Th17) and CD8⁺ T (Tc17) cells have been proven to play crucial roles in influenza virus infection, the changes and roles of Th17 and Tc17 cells in immune responses to H7N9 infection remain controversial. In this study, we found that the frequencies of Th17 and Tc17 cells among human peripheral blood mononuclear cells (PBMCs) as well as IL-17A protein and mRNA levels were markedly decreased in patients with acute H7N9 virus infection. A positive correlation was found between the serum IL-17A level and the frequency of these two cell groups. In vitro infection experiments revealed decreased Th17 and Tc17 cell frequency and IL-17A levels at various time points postinfection. In addition, Th17 cells were the predominant sources of IL-17A in PBMCs of patients infected with H7N9 virus. Taken together, our results indicate immune disorder in acute H7N9 infection and a restored Th17 and Tc17 cell frequency might serve as a biomarker for predicting recovery in patients infected with this virus.

Dual effect of T helper cell 17 (Th17) and regulatory T cell (Treg) in liver pathological process: From occurrence to end stage of disease

Liver disease is a complicated pathological status with acute or chronic progressions, causing a series of damages to liver and massive burden to public health and society. Th17 and Treg, two subsets of CD4⁺ T helper cells, seem to keep a subtle balance in the maintenance of organic immune homeostasis including liver. The dysfunction of Th17/Treg balance in liver has been proved associated with hepatic injury and disease. Herein, we summarized the research advance of Th17 and Treg cells in different phenotypes of liver diseases in the past decade. It is known to all that hepatic diseases start from stimulations or infections like virus, autoimmune, alcohol and so on in the early stage, which would cause inflammation. With the disease consistently existed, severe outcomes like cirrhosis and hepatocellular carcinoma appear finally. In conclusion, it is found that Th17 and Treg cells serve as an important role in the immune response imbalance of liver diseases from the beginning to the end stage. However, the effect of these two subsets of CD4⁺ T helper cells is not a stereotype. Pathological role which exacerbates the disease and protective character which inhibits damage to liver are co-existed in the effect of Th17 and Treg cells. Still, more studies should be carried out to enrich the understandings of liver disease and Th17/Treg immune balance in the future.

IL-17 and IL-17-producing cells and liver diseases, with focus on autoimmune liver diseases

The pro-inflammatory cytokine interleukin(IL)-17 and IL-17-producing cells are important players in the pathogenesis of many autoimmune / inflammatory diseases. More recently, they have been associated with liver diseases. This review first describes the general knowledge on IL-17 and IL-17 producing cells. The second part describes the in vitro and in vivo effects of IL-17 on liver cells and the contribution of IL-17 producing cells to liver diseases. IL-17 induces immune cell infiltration and liver damage driving to hepatic inflammation and fibrosis and contributes to autoimmune liver diseases. The circulating levels of IL-17 and the frequency of IL-17-producing cells are elevated in a variety of acute and chronic liver diseases. The last part focuses on the effects of IL-17 deletion or neutralization in various murine models. Some of these observed beneficial effects suggest that targeting the IL-17 axis could be a new therapeutic strategy to prevent chronicity and progression of various liver diseases.

Th17 cells over 5.9% at admission indicate poor prognosis in patients with HBV-related acute-on-chronic liver failure

Our previous study demonstrated that Th17 cells increased significantly in patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF). However, their prognostic role in HBV-ACLF patients remains unknown.Sixty-eight consecutive HBV-ACLF patients were enrolled in this cohort study. Th17 cells were examined using flow cytometry. Disease severity scores were assessed. ROC curves were used to evaluate the value in predicting prognosis. Survival was analyzed using Kaplan-Meier curves. Predictors of mortality were determined by regression analysis.Th17 cells were significantly higher in HBV-ACLF patients compared to patients with chronic hepatitis B and normal controls (both P < .001). Also, Th17 cells were higher in nonsurviving HBV-ACLF patients than in surviving patients (P = .014). Th17 cells were positively correlated with CLIF-Consortium ACLF (CLIF-C ACLF) score (r = 0.240, P = .048). ROC curves showed that the frequency of Th17 cells had accuracy in predicting 90-day prognosis equivalent to MELD, MELD-Na and CLIF-C ACLF scores in HBV-ACLF (P = .34, P = .26, and P = .15, respectively). More importantly, the area under the ROC curve (AUROC) increased when Th17 cells were combined with MELD, MELD-Na or CLIF-C ACLF score than using Th17 cells alone (P = .021, P = .006, and P = .023, respectively). Kaplan-Meier analysis revealed that higher Th17 cells (≥5.9%) were closely associated with poor overall survival in HBV-ACLF (P = .0086). Additionally, multivariate regression analysis showed that the frequency of Th17 cells over 5.9% was an independent predictor of mortality (OR = 0.154, P = .025).Circulating Th17 cells positively correlated with disease severity in HBV-ACLF. The frequency of Th17 cells over 5.9% could serve as a prognostic biomarker for HBV-ACLF patients.

TLR2 Expression in Peripheral CD4+ T Cells Promotes Th17 Response and Is Associated with Disease Aggravation of Hepatitis B Virus-Related Acute-On-Chronic Liver Failure

Th17 responses have been shown to play crucial roles in the pathogenesis of hepatitis B virus (HBV)-associated acute-on-chronic liver failure (ACLF). The mechanism underlying the enhanced Th17 responses in these patients remains largely unclear. Here we investigated toll-like receptors (TLRs) expression in peripheral T cells and their roles in Th17 cell differentiation and disease aggravation in ACLF patients. 18 healthy subjects (HS), 20 chronic HBV-infected (CHB) patients, and 26 ACLF patients were enrolled and examined for TLRs expression in peripheral blood mononuclear cells (PBMCs). The correlations of T cell TLR2 expression with the antigen non-specific Th17 responses and disease aggravation, as well as the Th17 response to TLR2 ligand stimulation were evaluated in ACLF patients. Compared to HS and CHB patients, ACLF patients showed a distinct TLRs expression pattern in PBMCs. Significantly increased TLR2 expression in T cells was observed in ACLF patients. The TLR2 expression in CD4+ T cells was correlated with the Th17 responses and the clinical markers for disease aggravation in ACLF patients. Moreover, TLR2 ligands stimulation promoted Th17 cell differentiation and response in PBMCs of ACLF patients. These findings implicate that TLR2 signaling plays critical roles in Th17 cell differentiation and disease aggravation of HBV-related ACLF.

Immunity and Fibrogenesis: The Role of Th17/IL-17 Axis in HBV and HCV-induced Chronic Hepatitis and Progression to Cirrhosis

Cirrhosis is a common final pathway for most chronic liver diseases; representing an increasing burden worldwide and is associated with increased morbidity and mortality. Current evidence has shown that, after an initial injury, the immune response has a significant participation in the ongoing damage, and progression from chronic viral hepatitis (CVH) to cirrhosis, driving the activation and maintenance of main fibrogenic pathways. Among immune deregulations, those related to the subtype 17 of T helper lymphocytes (Th17)/interleukin-17 (IL-17) axis have been recognized as key immunopathological and prognostic elements in patients with CVH. The Th17/IL-17 axis has been found involved in several points of fibrogenesis chain from the activation of stellate cells, increased expression of profibrotic factors as TGF-β, promotion of the myofibroblastic or epithelial–mesenchymal transition, stimulation of the synthesis of collagen, and induction of imbalance between matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). It also promotes the recruitment of inflammatory cells and increases the expression of proinflammatory cytokines such as IL-6 and IL-23. So, the Th17/IL-17 axis is simultaneously the fuel and the flame of a sustained proinflammatory and profibrotic environment. This work aims to present the immunopathologic and prognostic role of the Th17/IL-17 axis and related pathways in fibrogenesis and progression to cirrhosis in patients with liver disease due to hepatitis B virus (HBV) and hepatitis C virus (HCV).

Blockade of Neutrophil's Chemokine Receptors CXCR1/2 Abrogate Liver Damage in Acute-on-Chronic Liver Failure

Background

Neutrophils serve as critical players in the pathogenesis of liver diseases. Chemokine receptors CXCR1 and CXCR2 are required for neutrophil chemotaxis to the site of inflammation/injury and are crucial in hepatic inflammatory response. However, key mechanism of neutrophil-mediated liver injury in acute-on-chronic liver failure (ACLF) remains highly elusive; which could be targeted for the development of new therapeutic interventions.

Methods

To demonstrate the role of CXCR1/CXCR2-expressing neutrophils in hepatic injury, we investigated CXCR1/CXCR2 receptor expression in 17 hepatitis B virus-related ACLF patients in comparison to 42 chronic hepatitis B and 18 healthy controls. Mechanism of neutrophil-mediated cell death was analyzed by in vitro coculture assays and correlated with the patient data. In addition, to find out any etiological-based variations in ACLF, 19 alcohol-related ACLF patients were also included.

Results

In ACLF, neutrophils have high expression of CXCR1/CXCR2 receptors, which potentially participate in hepatocyte death through early apoptosis and necrosis in contact-dependent and -independent mechanisms. Importantly, blockade of CXCR1/CXCR2 with SCH 527123 antagonist significantly reduced cell death by targeting both the mechanisms. No etiology-based differences were seen between ACLF groups. Importantly, absolute neutrophil count was particularly higher in clinically severe ACLF patients and non-survivors (p < 0.0001). Multivariate analysis demonstrated ANC and CXCL8/IL-8 as a predictor of mortality. Further, receiver operating characteristics curve confirmed the cutoff of ANC >73.5% (sensitivity: 76.5% and specificity: 76.5%) and CXCL8/IL-8 >27% (sensitivity: 70% and specificity: 73%) in prediction of mortality.

Conclusion

Blockade of CXCR1/CXCR2 diminished the production of inflammatory mediators and reduced cell death; therefore, pharmacological neutralization of CXCR1/CXCR2 could provide novel therapeutic target in the management of ACLF.

Polymorphisms in the IL-17 Gene (rs2275913 and rs763780) Are Associated with Hepatitis B Virus Infection in the Han Chinese Population

AIM

Interleukin-17 (IL-17) can accelerate the release of many pro-inflammatory cytokines. The purpose of our study was to investigate the potential association between polymorphisms in the IL-17 gene and susceptibility to hepatitis B virus (HBV) infection in the Han Chinese population.

METHODS

We recruited 596 HBV-infected patients and 612 ethnically matched controls, who were then genotyped for the IL-17A and IL-17F polymorphisms, rs2275913 and rs763780, respectively, by using TaqMan probe-based real-time polymerase chain reaction. The frequencies of the alleles and genotypes in patients and controls were compared by the χ² test.

RESULTS

Statistically significant differences in genotypic and allelic frequencies were revealed at both polymorphic sites between HBV-positive patients and controls (rs2275913: genotype χ² = 37.74, p < 0.001 and allele χ² = 22.17, p < 0.001, odds ratio [OR] = 0.654, 95% confidence interval [CI] = 0.548-0.781. rs763780: genotype χ² = 19.80, p < 0.001 and allele χ² = 18.78, p < 0.001, OR = 0.507, 95% CI = 0.371-0.692).

CONCLUSIONS

These results indicate that the IL-17A rs2275913 and IL-17F rs763780 polymorphisms are associated with HBV infection in the Han Chinese population. We conclude that possession of the GG genotype and the G allele at rs2275913, and the TT genotype and the T allele at rs763780 might increase the risk of HBV infection. Larger-scale, multiracial studies are necessary to evaluate the role of IL-17 polymorphisms in relation to an enhanced risk of HBV infection.

Persistently elevated circulating Th22 reversely correlates with prognosis in HBV-related acute-on-chronic liver failure

BACKGROUND AND AIM

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is an acute deterioration of liver function on chronic liver disease with immune disorder. Th22 cells and IL-22 were correlated with inflammatory and autoimmune diseases. However, Th22 cells and IL-22 in the pathogenesis of HBV-ACLF remains to be elucidated. It was investigated the correlation between Th22 and prognosis in HBV-ACLF.

METHODS

Seventy-one HBV-ACLF and 65 chronic hepatitis B patients were recruited. The peripheral frequencies of Th22, Th17 and Th1, or IL-22 and IL-17 were determined, using flow cytometry or ELISA, respectively. It was further analyzed the correlation between Th22 mediated circulating IL-22 and survival rate of HBV-ACLF patients.

RESULTS

It was upregulated that the peripheral frequencies of Th22/Th17 cells as well as plasma IL-22 and IL-17 in HBV-ACLF patients, but the frequency of Th1 cells was decreased, compared with health controls. Elevated Th22 cells and IL-22 were correlated with HBV-ACLF disease severity. Elevated plasma IL-22 level (>29.5 pg/ml) was correlated with poor survival rate of HBV-ACLF patients at baseline, using Kaplan-Meier analysis.

CONCLUSIONS

Persistently elevated circulating Th22 reversely correlates with prognosis in HBV-ACLF. Th22 cells/IL-22 might be served as biomarkers for evaluating the prognosis of HBV-ACLF.

Key role of liver sinusoidal endothelial cells in liver fibrosis

Because of the prevalence of viral hepatitis and nonalcoholic fatty liver disease (NAFLD), liver fibrosis has become a very common disease in Asia and elsewhere in the world, constantly increasing the burden of care borne by society. Hepatic sinusoidal capillarization, characterized by gradually shrinking fenestrae on the surface of liver sinusoidal endothelial cells (LSECs) and the formation of an organized basement membrane, is an initial pathologic change associated with liver fibrosis. Basic and clinical studies have indicated that LSECs play a key role in hepatic sinusoidal capillarization by affecting various aspects of the development and progression of liver fibrosis. Reviewing studies on the effect of LSECs on liver fibrosis is essential to better understanding the pathogenesis of liver fibrosis and its mechanism of progression. Moreover, such a review will provide a theoretical basis for identifying new methods to promote the regression or even inhibition of fibrosis. This review will focus on structural and functional changes in LSECs during hepatic sinusoidal capillarization and the interaction between the micro-environment of the liver and the body's immune system.

Prostaglandin E2 As a Modulator of Viral Infections

Viral infections are a major cause of infectious diseases worldwide. Inflammation and the immune system are the major host defenses against these viral infection. Prostaglandin E2 (PGE2), an eicosanoid generated by cyclooxygenases, has been shown to modulate inflammation and the immune system by regulating the expression/concentration of cytokines. The effect of PGE2 on viral infection and replication is cell type- and virus-family-dependent. The host immune system can be modulated by PGE2, with regards to immunosuppression, inhibition of nitrogen oxide (NO) production, inhibition of interferon (IFN) and apoptotic pathways, and inhibition of viral receptor expression. Furthermore, PGE2 can play a role in viral infection directly by increasing the production and release of virions, inhibiting viral binding and replication, and/or stimulating viral gene expression. PGE2 may also have a regulatory role in the induction of autoimmunity and in signaling via Toll-like receptors. In this review the known effects of PGE2 on the pathogenesis of various infections caused by herpes simplex virus, rotavirus, influenza A virus and human immunodeficiency virus as well the therapeutic potential of PGE2 are discussed.

Association of IL-17A and IL-17F gene polymorphisms with chronic hepatitis B and hepatitis B virus-related liver cirrhosis in a Chinese population: A case-control study

BACKGROUND

Interleukin (IL)-17 has been shown to play an important role in tissue inflammation and in the pathogenesis of immune-related liver damage. Genetic variations in IL-17 gene may be associated with the development of hepatitis B virus (HBV) infection. However, literature is scanty regarding their association.

METHODS

We conducted a case-control study including 433 subjects (171 healthy controls, 130 patients with chronic hepatitis B [CHB]; and 132 patients with HBV-related liver cirrhosis [HBV-LC] to assess the association between IL-17A rs4711998, IL-17A rs2275913 and IL-17F rs763780 polymorphisms and risk of CHB and HBV-LC. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing.

RESULTS

Our results revealed a statistically significant association between IL-17A rs4711998 G allele and increased risk of HBV-LC risk (OR=1.541, 95% CI 1.057-2.246, P=0.025). Subjects carrying the IL-17A rs4711998 AG genotype were 1.75 times more likely to develop HBV-LC (OR=1.757, 95% CI 1.096-2.817, P=0.026). Stratification analysis indicated that IL-17A rs4711998 G allele and AG genotype enhanced the risk of HBV-LC development among men and older age (≥50years) subject groups. In addition, we found that GCT haplotype also might be a risk factor for HBV-LC (OR=2.448, 95% CI 1.137-5.271, P=0.019). Furthermore, no significant association between IL-17A rs2275913 and IL-17F rs763780 polymorphisms and CHB, HBV-LC risk was observed (P>0.05).

CONCLUSION

Our data provide the first evidence that the IL-17A rs4711998 genetic variant may contribute to HBV-LC susceptibility in a Chinese population.

Low Ratio of Treg to Th17 Cells After 36 Weeks of Telbivudine Therapy Predict HBeAg Seroconversion

Changes of Treg/Th17 cells ratio and their associated cytokines have some correlations with an immune modulatory effect of Telbivudine treatment. The aim of our study was to investigate the role of the dynamic ratio of Treg/Th17 cells in the mechanism of LdT therapy and their relationships with the clinical responses. We detected the frequency and cytokines production of Treg and Th17 cells in 28 hepatitis B envelope antigen (HBeAg)-positive CHB patients at 0, 12, 24, 36, 48, and 96 weeks after initial LdT therapy. LdT could upregulate the frequency of Th17 cells and Th17 cells associated cytokines, downregulated the frequency of Treg cells and level of TGF-β, which leads to the decrease of Treg/Th17 ratio in HBeAg-positive CHB patients. Treg/Th17 ratio at treatment week 36 could independently predict HBeAg seroconversion in the first 2 years of Telbivudine treatment. Telbivudine therapy can decrease Treg/Th17 ratio, which may predict HBeAg seroconversion during treatment.

Increase in frequencies of circulating Th-17 cells correlates with microbial translocation, immune activation and exhaustion in HIV-1 infected patients with poor CD4 T-cell reconstitution

We analyzed the association of circulating Th-17 cells (cTh-17) with immune activation (IA), immune exhaustion (IE) and regulatory T-cells (T-regs) in 20 human immunodeficiency virus-1 (HIV-1) infected patients with impaired restoration of CD4 T-cell counts despite prolonged suppression of plasma viremia (discordant) and compared it with 20 HIV-1 infected patients showing good immunologic and virologic responses (concordant) following highly active antiretroviral therapy (HAART). Discordant HIV-1 infected patients showed significantly higher frequencies of cTh-17 cells compared to concordant patients and healthy controls after PMA+Ionomicin stimulation. Discordant patients also showed higher CD4 T-cell immune activation (HLA-DR+CD38+) than concordant patients which directly correlated with microbial translocation. Additionally, CD4 T-cells of discordant patients showed higher frequencies of CD4 T-cells expressing multiple immune exhaustion markers (Tim3+PD-1+) which correlated with immune activation indicating that combined analysis of inhibitory molecules along with PD-1 might be a better predictor for immune exhaustion of CD4 T-cells. Increased cTh-17 cell frequency correlated inversely with CD4 T-cell percentages and absolute counts and directly with CD4 T-cell immune activation and T-reg frequencies. Persistent CD4 T-cell immune activation might favor differentiation of activated CD4 T-cells toward cTh-17 phenotype in discordant patients. Discordant patients had significantly lower baseline CD4 T-cell counts and higher viral load at the initiation of HAART and higher immune activation and immune exhaustion after being on HAART for long time indicating that these factors might be associated with an increase in cTh-17 cell frequency, thus, increasing the risk of disease progression despite virologic control.

Early warning and clinical outcome prediction of acute-on-chronic hepatitis B liver failure

Hepatitis B virus (HBV) associated acute-on-chronic liver failure (ACLF) is an increasingly recognized fatal liver disease encompassing a severe acute exacerbation of liver function in patients with chronic hepatitis B (CHB). Despite the introduction of an artificial liver support system and antiviral therapy, the short-term prognosis of HBV-ACLF is still extremely poor unless emergency liver transplantation is performed. In such a situation, stopping or slowing the progression of CHB to ACLF at an early stage is the most effective way of reducing the morbidity and mortality of HBV-ACLF. It is well-known that the occurrence and progression of HBV-ACLF is associated with many factors, and the outcomes of HBV-ACLF patients can be significantly improved if timely and appropriate interventions are provided. In this review, we highlight recent developments in early warning and clinical outcome prediction in patients with HBV-ACLF and provide an outlook for future research in this field.

Restoring homeostasis of CD4+ T cells in hepatitis-B-virus-related liver fibrosis

Immune-mediated liver injury is widely seen during hepatitis B virus (HBV) infection. Unsuccessful immune clearance of HBV results in chronic hepatitis and increases the risk of liver cirrhosis and hepatocellular carcinoma. HBV-related liver fibrosis (HBVLF), occurring as a result of HBV-induced chronic hepatitis, is a reversible, intermediate stage of chronic hepatitis B (CHB) and liver cirrhosis. Therefore, defining the pathogenesis of HBVLF is of practical significance for achieving better clinical outcomes. Recently, the homeostasis of CD4⁺ T cells was considered to be pivotal in the process of HBVLF. To better uncover the underlying mechanisms, in this review, we systematically retrospect the impacts of different CD4⁺ T-cell subsets on CHB and HBVLF. We emphasize CD4⁺ T-cell homeostasis and the important balance between regulatory T (Treg) and T helper 17 (Th17) cells. We discuss some cytokines associated with Treg and Th17 cells such as interleukin (IL)-17, IL-22, IL-21, IL-23, IL-10, IL-35 and IL-33, as well as surface molecules such as programmed cell death protein 1, cytotoxic T lymphocyte-associated antigen 4, T cell immunoglobulin domain and mucin domain-containing molecule 3 and cannabinoid receptor 2 that have potential therapeutic implications for the homeostasis of CD4⁺ T cells in CHB and HBVLF.

Gut dysbiosis in acute-on-chronic liver failure and its predictive value for mortality

BACKGROUND

Bacterial translocation from the gut plays an important role in the pathophysiology of acute-on-chronic liver failure (ACLF). However, gut dysbiosis in ACLF was not widely documented in previous studies.

AIM

This research characterized the fecal microbiota in patients with ACLF and analyzed the temporal stability of gut microbiota during illness.

METHODS

Fecal microbiota of 79 ACLF patients (42 patients were followed in the next 4 weeks after the first visit for longitudinal study) and 50 healthy controls was analyzed by 16S ribosomal DNA pyrosequencing.

RESULTS

There was a marked difference between the ACLF group and the control group. The overall microbial diversity and richness were significantly lower in ACLF than in controls. ACLF patients had lower abundance of Bacteroidaceae, Ruminococcaceae, and Lanchnospiraceae, but higher abundance of Pasteurellaceae, Streptococcaceae, and Enterecoccaceae. The relative abundance of Lachnospiraceae was obviously decreased in ACLF patients with hepatic encephalopathy. The gut microbiota kept relatively stable in a short term after the onset of ACLF. The use of antibiotics only showed moderate impacts on the gut microbiota. The relative abundance of Pasteurellaceae and Model of End Stage Liver Disease score were independent factors predicting mortality rate. Network analysis comparison showed robust correlations between specific bacterial families (Ruminococcaceae and Lachnospiraceae) and inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor alpha, IL-2) in ACLF patients.

CONCLUSIONS

These data suggest gut dysbiosis in ACLF and its predictive value for mortality. The results thus open up the possibility of designing diagnostic biomarkers and targeted probiotics aimed at decreasing mortality in ACLF.

Sustained Changes of Treg and Th17 Cells During Interferon-α Therapy in Patients with Chronic Hepatitis B

Chronic hepatitis B (CHB) is a worldwide infectious disease caused by hepatitis B virus (HBV). HBV mainly damages liver cells through immune response. The purpose of this study was to determine whether there were dynamic changes of Treg and Th17 cells and to judge the value of these indicators to antiviral treatment. Twenty-two CHB patients and selected 30 healthy adults were enrolled. Results showed that the expression of Treg (5.72±0.46 vs. 4.42±0.17, p=0.0019) and Th17 (3.94±0.64 vs. 2.66±3.12, p=0.0436) cells was significantly increased in CHB patients, as well as the level of interleukin-17 (IL-17) (16.88±5.37 vs. 8.59±3.31; p=0.004). Then, we monitored longitudinally the impact of the treatment with interferon-α and found that the suppression of viral replication induced by interferon-α resulted in a decrease in Treg, Th17 cells, and IL-17; we also found that the percentage of Treg and Th17 cells went up without clear evidence of clinical autoimmune disease at the end of treatment. Thus, Treg and Th17 cells might play an important role in interferon-α treatment to eliminate HBV. The level of changes may be served to determine the antiviral efficacy of interferon-α therapy.

Viral (hepatitis C virus, hepatitis B virus, HIV) persistence and immune homeostasis

Immune homeostasis is a host characteristic that maintains biological balance within a host. Humans have evolved many host defence mechanisms that ensure the survival of individuals upon encountering a pathogenic infection, with recovery or persistence from a viral infection being determined by both viral factors and host immunity. Chronic viral infections, such as hepatitis B virus, hepatitis C virus and HIV, often result in chronic fluctuating viraemia in the face of host cellular and humoral immune responses, which are dysregulated by multi-faceted mechanisms that are incompletely understood. This review attempts to illuminate the mechanisms involved in this process, focusing on immune homeostasis in the setting of persistent viral infection from the aspects of host defence mechanism, including interferon-stimulated genes, apolipoprotein B mRNA editing enzyme catalytic polypeptide 3 (APOBEC3), autophagy and interactions of various immune cells, cytokines and regulatory molecules.

Th17 cells in autoimmune and infectious diseases

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

Interleukin-17 enhances immunosuppression by mesenchymal stem cells

IL-17 is one of the most potent and most actively investigated proinflammatory cytokines. In this study, we examined the effect of IL-17 on mesenchymal stem cells (MSCs) under the influence of inflammatory cytokines. Ironically, IL-17 dramatically enhanced the immunosuppressive effect of MSCs induced by IFNγ and TNFα, revealing a novel role of IL-17 in immunosuppression. Interestingly, we found that this action of IL-17 was dependent on the promoted expression of a key immune suppressive molecule, inducible nitric oxide synthase (iNOS), in MSCs. In a concanavalin A (ConA)-induced hepatitis mouse model, we found that IL-17 also enhanced the in vivo immunosuppressive effect of MSCs in an iNOS-dependent manner. Moreover, this promoting effect of IL-17 was found to be exerted through enhancing mRNA stability by modulating the protein level of ARE/poly(U)-binding/degradation factor 1 (AUF1), a well-known factor that promotes mRNA decay. In auf1^−/− MSCs, IFNγ and TNFα could induce maximal immunosuppressive effect, both in vitro and in vivo, without the need for IL-17. Thus, our studies demonstrated that in the presence of MSCs, IL-17 promotes immunosuppression.

Changes in circulating Foxp3+ regulatory T cells and interleukin-17-producing T helper cells during HBV-related acute-on-chronic liver failure

AIM: To longitudinally investigate cytokine gene expression and protein levels in Th17 and Treg cells, to observe T-cell phenotypes during hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACHBLF) and to analyze changes in Th17 and Treg phenotypes during disease progression.

METHODS: We measured the expression of seven Th17/Treg differentiation-related genes and serum concentrations of the corresponding cytokines in 18 ACHBLF, 18 chronic hepatitis B (CHB) disease controls and 10 healthy controls (HCs) by real-time quantitative PCR and enzyme linked immunosorbent assay. Peripheral Th17 and Treg cell frequencies were analyzed by flow cytometry.

RESULTS: From the onset of ACHBLF, patients presented with a conductive Th17 differentiation cytokine environment accompanied by high Th17 frequency and high serum IL-17 levels, which were sustained throughout the disease course. The Treg-related cytokine IL-2 and Foxp3 were also up-regulated from disease onset, and Foxp3 gene expression showed a gradually increasing trend during ACHBLF. The circular phenotype of Treg and Th17 cells showed changes from the onset of ACHGLF. At disease onset, Th17 frequency increased significantly compared with both CHB and HCs, but Treg cell frequency decreased significantly compared with CHB. During the ACHBLF event, Th17 frequency remained higher compared with HCs, but decreased sharply from the peak point to the recovery point; Treg cell frequency increased gradually during the ACHBLF event. Treg and Th17 cell counts correlated with ACHBLF development; in all patients, serum IL-17 levels significantly correlated with patient serum ALT levels. In survivors, Th17 frequency at the onset point and the Treg to Th17 ratio at the peak point correlated with the patient’s model for end stage liver disease (MELD) plus sodium (MELD-Na) score. The Treg to Th17 ratio and the Th17 frequency at onset were significant predictors of patient survival. Low Treg/Th17 cell ratios at the onset predicted poor survival. Survivors exhibited an initial decrease in the circulating Treg/Th17 ratio from the onset to the peak time, and subsequently displayed a continuous increase.

CONCLUSION: Treg and Th17 cells showed changes in genes, protein levels and T cell phenotypes during ACHBLF events. An increased Treg/Th17 ratio was associated with the survival of ACHBLF patients.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Phosphorylated STAT3 and PD-1 regulate IL-17 production and IL-23 receptor expression in Mycobacterium tuberculosis infection

We studied the factors that regulate IL-23 receptor expression and IL-17 production in human tuberculosis infection. Mycobacterium tuberculosis (M. tb)-stimulated CD4(+) T cells from tuberculosis patients secreted less IL-17 than did CD4(+) T cells from healthy tuberculin reactors (PPD(+) ). M. tb-cultured monocytes from tuberculosis patients and PPD(+) donors expressed equal amounts of IL-23p19 mRNA and protein, suggesting that reduced IL-23 production is not responsible for decreased IL-17 production by tuberculosis patients. Freshly isolated and M. tb-stimulated CD4(+) T cells from tuberculosis patients had reduced IL-23 receptor and phosphorylated STAT3 (pSTAT3) expression, compared with cells from PPD(+) donors. STAT3 siRNA reduced IL-23 receptor expression and IL-17 production by CD4(+) T cells from PPD(+) donors. Tuberculosis patients had increased numbers of PD-1(+) T cells compared with healthy PPD(+) individuals. Anti-PD-1 antibody enhanced pSTAT3 and IL-23R expression and IL-17 production by M. tb-cultured CD4(+) T cells of tuberculosis patients. Anti-tuberculosis therapy decreased PD-1 expression, increased IL-17 and IFN-γ production and pSTAT3 and IL-23R expression. These findings demonstrate that increased PD-1 expression and decreased pSTAT3 expression reduce IL-23 receptor expression and IL-17 production by CD4(+) T cells of tuberculosis patients.

Peripheral T lymphocyte subset imbalances in children with enterovirus 71-induced hand, foot and mouth disease

Inflammatory mediators (i.e. cytokines) play a pivotal role in the regulation of pathophysiological processes during EV71-induced hand, foot and mouth disease (HFMD). Different T cell subsets have distinct cytokine secretion profiles, and alteration in the T cell subsets frequency (imbalance) during infection leads to changed cytokine patterns. However, the effects of EV71 infection on T cell subsets were not clear. The objective of this study was to determine whether EV71-induced HFMD can be explained by the emergence of particular T-cell subsets (Th1, Th2, Tc1, Tc2, Th17, Tc17 and Treg cells) and the cytokine they produced (IFN-γ, IL-4, IL-17A and TGF-β1), as well as distinct responses to EV71 infection. We found that when compared to the control group, the percentage of Th1 and Tc1 cells was significantly higher in mild and severe HFMD group. Similar results were found in the Th1/Th2 ratio and IFN-γ levels. On the other hand, the percentage of Th17 cells and IL-17A levels were the highest in severe HFMD cases, and lowest in controls. Similar trend was also found for the Th17/Treg cell ratio. An optimal cutoff value of 2.15% for Th17 cell and 6.72 pg/ml for IL-17A provided a discriminatory value for differentiating the severity of HFMD cases by receiver operating characteristic curve analyses. These findings reveal that the Th1/Th2 and Th17/Treg imbalance exist in HFMD patients, suggesting their involvement in the pathogenesis of EV71 infection, which may have potential value as biomarkers.

Is IL-17 an accomplice contributing to salivary gland damage during CMV infection?

Aim: This study aimed to explore the potential role of IL-17 in the pathological damage to the salivary gland during CMV infection. Materials & methods: For all studies, 4-week-old female BALB/c mice were used. Mouse embryo fibroblast cells were isolated from embryos of pregnant mice. The Smith murine CMV (MCMV) strain was propagated and obtained from homogenates of the salivary glands. BALB/c mice were randomly divided into two groups. Mice in one group were infected with Smith MCMV to establish disseminated infection; mice in the other group were controls. Four mice of each group were randomly chosen to be harvested on days 3, 7, 14 and 28. Viral titers in salivary gland tissues were determined using a standard plaque assay; IL-17+ T cells in the spleen were analyzed by flow cytometry; the expressions of IL-17 and IL-17 receptor (IL-17R) mRNA was measured by reverse transcription PCR; and the pathology of the salivary glands in infected mice were assessed by hematoxylin and eosin staining. Results: The viral titers in salivary gland tissues, which were much higher than those of other organs, elevated on day 7 and peaked on day 14, then gradually declined on day 28. The percentages of CD4+IL-17+ T cells were increased in MCMV-infected mice compared with controls, with the main increase of CD4+IL-17+ T cells being Th17 cells (p < 0.05). In salivary gland tissues, the expression of IL-17 and IL-17R mRNA increased significantly and achieved the highest level on day 14, which was significantly higher than that of the controls (p < 0.05). Compared with controls, serious inflammatory cellular infiltrates in the salivary glands were present on day 7 after MCMV infection, and on day 14, many of the cellular infiltrate became larger and coalesced with neighboring foci. We found that IL-17 and IL-17R were enriched in the salivary glands when the tissues were mainly injured. Conclusion: The results illustrated that the inflammatory factors, IL-17 and IL-17R, possibly contributed to the process of viral infection and played a part in inducing pathological damage of the salivary gland.

The co-inhibitory pathway and cellular immune imbalance in the progress of HBV infection

OBJECTIVE

Chronic hepatitis B (CHB) affects 400 million people and is the most common cause of liver cirrhosis (LC) and hepatocellular carcinoma (HCC) worldwide. Cellular immune regulation plays an important role in determining the infection outcome. Co-signal molecules and Th17/Treg were studied to explore their association with the progression of HBV infection.

METHODS

Ninety-four HBV-infected patients were categorized into three groups: 31 patients with LC caused by CHB, 30 with HCC caused by CHB and 33 with HCC caused by CHB. Co-signal molecules, Th17/Treg, and Stat3 and Stat5 were analyzed by flow cytometry.

RESULTS

CHB patients who progressed to LC or HCC showed a significantly higher level of co-inhibitory molecules such as BTLA and PD-1, while there was no significant difference in co-stimulatory molecules among LC, HCC and CHB. Stat3 and Stat5 were significantly increased in LC and HCC compared to CHB patients.

CONCLUSION

Co-inhibitory molecules play more important roles than co-stimulatory molecules. Increased PD-1 and BTLA/HVEM inhibited immune cells and the immune process. At the same time activated Stat3 and Stat5 stimulate the key factors in differentiation of Th17 and Treg, thus leading to imbalanced expansion of Th17 and Treg; immune tolerance was induced and HBV persistent. This resulted in hepatic inflammation that progressed to cirrhosis and carcinoma.

Increased CD163 expression is associated with acute-on-chronic hepatitis B liver failure

AIM: To assess CD163 expression in plasma and peripheral blood and analyze its association with disease in acute-on-chronic hepatitis B liver failure (ACHBLF) patients.

METHODS: A retrospective study was conducted from January 1, 2011 to January 1, 2012. Forty patients with ACHBLF (mean age 44.48 ± 12.28 years, range 18-69 years), 40 patients with chronic hepatitis B (CHB) (mean age 39.45 ± 12.22 years, range 21-57 years) and 20 age- and sex-matched healthy controls (mean age 38.35 ± 11.97 years, range 28-60 years) were included in this study. Flow cytometry was used to analyze the frequency of CD163+ peripheral blood mononuclear cells (PBMCs) and surface protein expression of CD163. Real-time transcription-polymerase chain reaction was performed to assess relative CD163 mRNA levels in PBMCs. Plasma soluble CD163 (sCD163) levels were measured by enzyme-linked immunosorbent assay. Clinical variables were also recorded. Comparisons between groups were analyzed by Kruskal-Wallis H test and Mann-Whitney U test. Statistical analyses were performed using SPSS 15.0 software and a P value < 0.05 was considered statistically significant.

RESULTS: Flow cytometry showed that the population of CD163+ PBMCs was significantly greater in ACHBLF patients than in CHB patients and healthy controls (47.9645% ± 17.1542%, 32.0975% ± 11.0215% vs 17.9460% ± 6.3618%, P < 0.0001). However, there were no significant differences in mean fluorescence intensity of CD163+ PBMCs within the three groups (27.4975 ± 11.3731, 25.8140 ± 10.0649 vs 20.5050 ± 6.2437, P = 0.0514). CD163 mRNA expression in ACHBLF patients was significantly increased compared with CHB patients and healthy controls (1.41 × 10^-2± 2.18 × 10^-2, 5.10 × 10^-3± 3.61 × 10^-3vs 37.0 × 10^-4± 3.55 × 10^-4, P = 0.02). Plasma sCD163 levels in patients with ACHBLF were significantly increased compared with CHB patients and healthy controls (4706.2175 ± 1681.1096 ng/mL, 1089.7160 ± 736.8395 ng/mL vs 435.9562 ± 440.8329 ng/mL, P < 0.0001). In ACHBLF patients, plasma sCD163 levels were significantly positively associated with model for end-stage liver disease scores (r = 0.5075, P = 0.008), hepatitis B virus-DNA (r = 0.6827, P < 0.0001), and negatively associated with prothrombin activity (r = -0.3348, P = 0.0347), but had no correlation with total bilirubin (r = 0.2551, P = 0.1122). Furthermore, sCD163 was obviously elevated in non-surviving patients compared with surviving patients with ACHBLF (5344.9080 ± 1589.5199 ng/mL vs 3641.7333 ± 1264.5228 ng/mL, P = 0.0321).

CONCLUSION: CD163 and sCD163 may be related to disease severity and prognosis in ACHBLF patients.

Th17 cells and liver diseases

In recent years, it has been demonstrated that T helper cells 17 (Th17) are closely related to the occurrence and development of many kinds of liver diseases such as viral hepatitis, autoimmune liver diseases and fatty liver diseases. Th17 cells are a new CD4⁺ T cell subset, which can interact with Th1, Th2 and Treg cells. There exists complex antagonistic or collaborative relationship among these cells. Understanding the role of Th17 cells in liver diseases will help explore the pathogenesis and treatment of these diseases.