Changes in the balance between Treg and Th17 cells in patients with chronic hepatitis B

Sulforaphane effectively inhibits HBV by altering Treg/Th17 immune balance and the MIF-macrophages polarizing axis in vitro and in vivo

BACKGROUND

Hepatitis B virus (HBV) infection is a major public health problem. After HBV infection, viral antigens shift the immune balance in favor of viral escape. Sulforaphane (SFN) is a traditional Chinese medicine.It regulates multi-biological activities, including anti-inflammation, anticancer, and antiviral. However, few studies reported that SFN can inhibit HBV infection before.

METHODS

An immunocompetent HBV CBA/CaJ mouse model and a co-culture model were used to explore the effect of SFN on HBV and whether SFN altered the immune balance after HBV infection.

RESULTS

We found that SFN was able to reduce HBV DNA, cccDNA, HBsAg, HBeAg, and HBcAg levels in serum and liver tissues of HBV-infected mice. In vitro and in vivo experiments showed that SFN could significantly increase the expression of Cd86 and iNOS and inhibit the expression of Arg1 on macrophages after HBV infection. After SFN administration, Th17 markers in liver tissue and serum were significantly increased. There was no significant changes in the proportion of Treg cells in peripheral blood, but a significant increase in the proportion of Th17 cells and decrease of the Treg/Th17 ratio. Using a network pharmacology approach, we predicted macrophage migration inhibitory factor (MIF) as a potential target of SFN and further validated that MIF expression was significantly increased after HBV infection and SFN significantly inhibited MIF expression both in vitro and in vivo. There was an upward trend in HBV markers (p>0.05) after MIF overexpression. Overexpression of MIF combined with the use of SFN resulted in a significant reversion in the expression of HBV markers and polarization of macrophages towards the M1 phenotype.

CONCLUSION

Our results indicated that immunocompetent HBV CBA/CaJ mouse model is a good model to evaluate HBV infection. SFN could inhibit the expression of HBV markers, promote polarization of macrophages towards the M1 phenotype after HBV infection, change the proportion of Treg and Th17 cells. Our findings demonstrate that SFN inhibit HBV infection by inhibiting the expression of MIF and promoting the polarization of macrophages towards the M1 phenotype, which illustrates a promising therapeutic approach in HBV infection.

Predictive value of Th17 and Treg cells at baseline for HBsAg loss in chronic hepatitis B patients with low HBsAg quantification treated with pegylated interferon and nucleos(t)ide analogue

Background and aims

The primary goal of chronic hepatitis B (CHB) treatment is to reduce hepatitis B surface antigen (HBsAg). T helper 17 (Th17) and regulatory T (Treg) cells are essential for the development of CHB. However, how Th17 and Treg cells contribute to HBsAg loss is still unknown. Therefore, this study aimed to search for the predictive value of Th17 and Treg cells for HBsAg loss in CHB patients with low HBsAg quantification.

Methods

The study included 99 hepatitis B e antigen (HBeAg)-negative CHB patients who had completed a year of nucleos(t)ide analogue (NA) monotherapy and had received both NA and pegylated interferon (PEG-IFN) treatment for less than 96 weeks (96 wk). In the cured group, 48 patients lost HBsAg within 48 wk, while 51 patients did not (uncured group). Blood samples and clinical data were collected for research.

Results

During PEG-IFN and NA combination therapy, the proportion of Th17 cells in the cured group increased significantly, while the proportion of Treg cells in the uncured group increased. From 0 to 24 wk, the proportion of Th17 cells in the cured group was significantly higher than in the uncured group, while the opposite was true for Treg cells. Patients with alanine aminotransferase (ALT) ≥ 2.5 upper limit of normal (ULN) at 12 wk had a higher proportion of Th17 cells and a lower proportion of Treg cells than those with ALT <2.5 ULN at 12 wk. Additionally, the proportion of Th17 cells is inversely associated with the level of HBsAg, whereas the level of Treg cells is positively related to HBsAg quantification. The clinical cure index, including age, HBsAg quantification, and the proportions of Th17 and Treg cells, had a higher area under the curve (0.957) for predicting HBsAg loss when compared to the proportions of Th17 and Treg cells and HBsAg quantification alone.

Conclusions

Combined with quantification of HBsAg, the proportions of Th17 cells and Treg cells at baseline can be used as good predictors of HBsAg loss in patients with low HBsAg quantification treated with NA and PEG-IFN.

LAG3+ erythroid progenitor cells inhibit HBsAg seroclearance during finite pegylated interferon treatment through LAG3 and TGF-β

HBsAg seroclearance, the ideal aim of anti-hepatitis B virus (HBV) treatment, cannot be achieved easily. Anemia is another common issue for chronic hepatitis B (CHB) patients, which leads to elevation of erythroid progenitor cells (EPCs) and immune suppression in cancer. This study investigated the role of EPCs in HBsAg seroclearance following pegylated interferon-α (PEG-IFN) treatment. CD45+EPC accumulation in CHB patients and an AAV/HBV mice model was found in the circulation and liver by flow cytometry and immunofluorescence tests. Wright-Giemsa staining showed that these pathological CD45+EPCs presented elevated erythroid cells with relative immature morphologies and atypical cells compared with the control cells. CD45+EPCs were associated with immune tolerance and decreased HBsAg seroclearance during finite PEG-IFN treatment. CD45+EPCs suppressed antigen non-specific T cell activation and HBV-specific CD8+T cells, partially through transforming growth factor β (TGF-β). RNA-seq revealed that CD45+EPCs in patients with CHB presented a distinct gene expression profile compared with CD45-EPCs and CD45+EPCs from cord blood. Notably, CD45+EPCs from patients with CHB expressed high level of Lymphocyte-activation gene 3 (LAG3), an immune checkpoint molecule, and were then defined as LAG3+EPCs. LAG3+EPCs diminished the function of antigen presenting cells through LAG3, which was another mechanism by which LAG3+EPCs' suppressed HBV-specific CD8+T cells. Anti-LAG3 and anti-TGF-β combination treatment decreased serum HBeAg, HBV DNA levels and HBsAg level, as well as HBsAg-expression in hepatocytes during PEG-IFN treatment in the AAV/HBV mice model. Conclusions: LAG3+EPCs inhibited the efficacy of PEG-IFN treatment on HBsAg seroclearance induced by LAG3 and TGF-β. Anti-LAG3, anti-TGF-β and PEG-IFN combination treatment might facilitate HBV clearance.

Plasma cytokine profile in occult HBV-infected blood donors

Aim: Cytokine profile in occult HBV infection (OBI) was systematically investigated to identify the immunopathogenesis of OBI. Materials & methods: A total of 46 OBI, ten asymptomatic hepatitis B surface antigen carriers, ten chronic hepatitis B and 12 healthy blood donors were recruited. A total of 21 plasma cytokines were detected. Results: Compared with healthy blood donors, elevated plasma Th1, Th2, Th17 and immune regulatory associated cytokines were observed in OBI. Almost no significant difference was found for these cytokines among OBI, asymptomatic hepatitis B surface antigen carriers and chronic hepatitis B. OBI displayed the predominance of type 2 and regulatory immunity. Conclusion: OBI displayed the general cytokine profile of chronic HBV infection, which might contribute to virus persistence and the presence of the liver microinflammatory environment. The clinical implications of OBI deserve more attention.

Cytokines and Chemokines in HBV Infection

Chronic hepatitis B virus (HBV) infection remains a leading cause of hepatic inflammation and damage. The pathogenesis of chronic hepatitis B (CHB) infection is predominantly mediated by persistent intrahepatic immunopathology. With the characterization of unique anatomical and immunological structure, the liver is also deemed an immunological organ, which gives rise to massive cytokines and chemokines under pathogenesis conditions, having significant implications for the progression of HBV infection. The intrahepatic innate immune system is responsible for the formidable source of cytokines and chemokines, with the latter also derived from hepatic parenchymal cells. In addition, systemic cytokines and chemokines are disturbed along with the disease course. Since HBV is a stealth virus, persistent exposure to HBV-related antigens confers to immune exhaustion, whereby regulatory cells are recruited by intrahepatic chemokines and cytokines, including interleukin-10 and transforming growth factor β, are involved in such series of causal events. Although the considerable value of two types of available approved treatment, interferons and nucleos(t)ide analogues, effectively suppress HBV replication, neither of them is sufficient for optimal restoration of the immunological attrition state to win the battle of the functional or virological cure of CHB infection. Notably, cytokines and chemokines play a crucial role in regulating the immune response. They exert effects by directly acting on HBV or indirectly manipulating target immune cells. As such, specific cytokines and chemokines, with a potential possibility to serve as novel immunological interventions, combined with those that target the virus itself, seem to be promising prospects in curative CHB infection. Here, we systematically review the recent literature that elucidates cytokine and chemokine-mediated pathogenesis and immune exhaustion of HBV infection and their dynamics triggered by current mainstream anti-HBV therapy. The predictive value of disease progression or control and the immunotherapies target of specific major cytokines and chemokines in CHB infection will also be delineated.

5-Aza-2'-deoxycytidine may enhance the frequency of T regulatory cells from CD4+ naïve T cells isolated from the peripheral blood of patients with chronic HBV infection

OBJECTIVES

Methylation pattern of gene modification is essential for the differentiation of T regulatory cells (Tregs) and 5-Aza-2'-deoxycytidine is a common inhibitor of methylation. This study aimed to investigate the potential effects of Treg polarizing conditions and 5-Aza-2'-deoxycytidine treatment in the differentiation of naïve T cells during chronic hepatitis B virus (HBV) infection.

METHODS

The frequency of Tregs in peripheral blood was determined by flow cytometry from patients with chronic hepatitis B (CHB) (n = 51), liver cirrhosis (LC) (n = 47), hepatocellular carcinoma (HCC) (n = 40) and healthy controls (HCs) (n = 17). Gene expression were detected by qRT-PCR and DNA methyltransferases (DNMT) Activity was also determined.

RESULTS

The frequency of Tregs and Foxp3 expression in peripheral blood from 5-Aza-2'-deoxycytidine-treated groups were higher than that with acetic acid treatment as a control. Foxp3 mRNA and the frequency of Tregs derived from naïve CD4+T cells from peripheral blood of patients with HCC or LC were more pronounced compared with HCs. 5-Aza-2'-deoxycytidine may have induced a more pronounced upward trend of PD-1 expression in HBV patients.

CONCLUSIONS

5-Aza-2'-deoxycytidine mediated demethylation has potential effects on enhancing the differentiation of naïve T cells to Tregs in chronic HBV infection.

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

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

Immune Checkpoints in Viral Infections

As evidence has mounted that virus-infected cells, such as cancer cells, negatively regulate the function of T-cells via immune checkpoints, it has become increasingly clear that viral infections similarly exploit immune checkpoints as an immune system escape mechanism. Although immune checkpoint therapy has been successfully used in cancer treatment, numerous studies have suggested that such therapy may also be highly relevant for treating viral infection, especially chronic viral infections. However, it has not yet been applied in this manner. Here, we reviewed recent findings regarding immune checkpoints in viral infections, including COVID-19, and discussed the role of immune checkpoints in different viral infections, as well as the potential for applying immune checkpoint blockades as antiviral therapy.

HBV promotes the recruitment of IL-17 secreting T cells via chemokines CCL22 and CCL17

BACKGROUND AND AIMS

Little is known about the mechanisms of IL-17 secreting T cells accumulation in HBV-transfected livers. Here, we investigated the role of the chemokines CCL17, CCL20 and CCL22 in this process.

METHODS

Peripheral blood and liver tissues were obtained from 30 chronic hepatitis B (CHB) patients and 15 healthy volunteers and were evaluated by flow cytometric analysis and immunohistochemistry. Chemokine production by monocyte-derived dendritic cells (MoDCs) cocultured with HBV-transfected or untransfected Huh7 cells was measured by quantitative real-time PCR and enzyme-linked immunosorbent assay. The chemotactic activity of the culture supernatants was also tested.

RESULTS

The proportions of IL-17 secreting CD4 (Th17) and CD8 (Tc17) T cells were both increased in liver and peripheral blood mononuclear cells of CHB patients compared to those in HVs. CHB patients showed higher intrahepatic levels of CCL17 mRNA, CCL22 mRNA, CCR6 mRNA and CCR4 mRNA than HVs. The expression of CCR6 and CCR4 on the surface of Th17 and Tc17 cells in CHB patients was also significantly higher than that in HVs. Significant correlations existed between the CCR4/CCR6 levels and both the alanine transaminase levels and HBV DNA loads. Contact between MoDCs and pBlue-HBV-transfected Huh7 cells induced the expression of CCL17 and CCL22 dependent on the dose of HBV DNA. However, CCL20 expression was lower in CHB patients than in HVs. Transwell experiments showed that upregulation of CCL17 and CCL22 enhanced the migration of IL-17 secreting T cells.

CONCLUSIONS

Contact of HBV-transfected cells with MoDCs induces CCL17 and CCL22 chemokine production, which may favour the recruitment of Th17 and Tc17 cells to liver tissue in CHB. Our results reveal the mechanism of IL-17 secreting T cells recruitment to liver tissue and thus provide new immunotherapy targets for CHB patients.

Role of Foxp3/Treg and RORγt/Th17 imbalance in chronic hepatitis B virus infection

A wide range of immune-mediated liver damage can be seen during infection with hepatitis B virus (HBV). Failure of HBV immune clearance leads to chronic hepatitis and greatly increases the risk of liver cirrhosis and hepatocellular carcinoma. Recently, there have been many studies on the relationship between the outcome of HBV infection and the immune status of patients. The immune response of T lymphocytes in HBV infection plays an important role, especially the imbalance of regulatory T cells (Treg)/Helper T cell 17 (Th17). The imbalance between the Treg and Th17 is an important mechanism of persistent HBV infection and inflammatory injury of the liver. To better reveal the underlying mechanisms, we systematically review the roles of Treg and Th17 and discuss the relationship between Treg and Th17 during HBV infection as well as the changes in the two related specific transcription factors, retinoid-related orphan nuclear receptor γt (RORγt) and forkhead/winged helix family transcription factor 3 (Foxp3). The research on HBV immunotargeting therapy in recent years has suggested the role of Foxp3/Treg and RORγt/Th17 imbalance in HBV infection. Such findings provide new ideas for the treatment of chronic hepatitis B.

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

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

Interleukin-35 modulates the balance between viral specific CD4+CD25+CD127dim/- regulatory T cells and T helper 17 cells in chronic hepatitis B virus infection

Background

Interleukin (IL)-35 regulates imbalance between regulatory T cells (Tregs) and T helper (Th) 17 cells, leading to an important modulator in autoimmune disorder, cancer, and infectious diseases. Our previous study revealed an immunosuppressive activity of IL-35 in chronic hepatitis B virus (HBV) infection. Thus, the aim of the current study was to investigate the role of regulatory function of IL-35 to viral specific Tregs/Th17 cells balance in chronic HBV infection.

Methods

A total of 44 HLA-A2 restricted chronic HBV infected patients, including 21 of chronic hepatitis B (CHB) and 23 of asymptomatic HBV carriers (ASC) were enrolled. Purified CD4⁺ T cells or CD4⁺CD25⁺CD127^dim/− Tregs were stimulated with recombinant IL-35. HBV core antigen specific Tregs and Th17 cells were determined by flow cytometry. FoxP3 and RORγt mRNA was measured by real-time PCR. Cytokines production (IL-10 and IL-17) was investigated by ELISA.

Results

Peripheral viral specific Tregs was comparable between CHB and ASC. However, increased percentage of viral specific Th17 cells was found in CHB, leading to the reduction of Tregs/Th17 ratio in CHB patients. IL-35 stimulation elevated viral specific Tregs, but not Th17 cells frequency, in both CHB and ASC, resulting in the elevation of Tregs/Th17 ratio in both groups. This process was accompanied by increased expression of FoxP3 mRNA and IL-10 production, and decreased IL-17 secretion and STAT3 phosphorylation in purified CD4⁺ T cells. Moreover, IL-35 stimulation inhibited viral specific Th17-like phenotype differentiation from Tregs in CHB patients. Effective anti-HBV therapy did not affect viral specific Tregs/Th17 cells frequency or IL-35 expression in CHB patients, however, reduced responsiveness of CD4⁺ T cells or Tregs to IL-35 stimulation in vitro.

Conclusion

Our findings indicated that IL-35 regulation to viral specific Tregs/Th17 balance may contribute to viral persistence in chronic HBV infection.

The balance of type 1 and type 2 immune responses in the contexts of hepatitis B infection and hepatitis D infection

BACKGROUND AND AIM

Hepatitis delta virus (HDV) infection is the most rapidly progressive chronic viral hepatitis. Little is understood about the immune responses to HDV. This study aims to characterize the systemic immune environments of hepatitis B virus (HBV) and HDV patients at various disease stages.

METHODS

A total of 129 subjects were evaluated: 53 HBV, 43 HDV, and 33 healthy controls. HBV and HDV subjects were categorized by aspartate aminotransferase to platelet ratio index (APRI) into mild (APRI < 0.5), moderate, and severe (APRI > 1.0). Serum cytokines and immune markers were assessed at a single treatment-naïve time-point.

RESULTS

Type 1 cytokines are elevated in both HBV and HDV. Both groups show higher tumor necrosis factor-α (TNF-α), interleukin (IL)-12p40, and C-X-C motif chemokine ligand 9 when compared with controls (all P < 0.05). However, only HBV group displayed elevated γ-interferon compared with controls. Type 2 cytokines are elevated in HBV. HBV group shows higher IL-4, IL-13, and C-C motif chemokine ligand (CCL) 26 compared with healthy controls and HDV. Chemokines CCL2 and CCL13 are lower in HDV. When assessing ratios, HDV displays higher γ-interferon/IL-4, TNF-α/IL-4, and TNF-α/IL-13 ratios than HBV and controls.

CONCLUSION

Hepatitis B virus and HDV subjects show similarly elevated type 1 cytokines. HDV subjects display relatively lower type 2 cytokines. These differences in the systemic immune environments, particularly the predominance of type 1 responses, may contribute to the comparatively rapid progression of HDV disease. Characterization of the imbalance in type 1 and type 2 immunity unique HDV has the potential to provide immunological insights for designing therapeutic targets in HDV-associated disease progression.

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.

Detection of Treg/Th17 cells and related cytokines in peripheral blood of chronic hepatitis B patients combined with thrombocytopenia and the clinical significance

Changes of regulatory T (Treg) cells and Th17 cells, and related cytokines in peripheral blood of patients with chronic hepatitis B combined with thrombocytopenia were investigated to explore the relationship with treatment outcomes. A total of 45 chronic hepatitis B patients combined with thrombocytopenia were selected in Heilongjiang Provincial Hospital from June 2015 to December 2016. All patients were treated with prednisolone acetate + γ globulins for 60 days. Treg cells and Th17 cells in peripheral blood were detected by flow cytometry, and IL-10, TGF-β, IL-17, IL-21 and IL-22 in peripheral blood were detected by ELISA before and after treatment. No significant differences in the percentages of Treg and Th17, and levels of IL-10, TGF-β, IL-17, IL-21 and IL-22 were found in non-responders (n=17, platelets <100×10⁹/l) before and after treatment (P>0.05). After treatment, percentage of Treg was significantly increased (higher than that of non-responders) and percentage of Th17 was significantly decreased (lower than that of non-responders) in responders (P<0.05). In addition, serum levels of IL-10 and TGF-β were significantly increased (higher than that of non-responders) and serum levels of IL-17, IL-21 and IL-22 were significantly decreased (lower than that of non-responders) in responders (P<0.05). The results showed that after treatment, the number of Treg cells was increased, the number of Th17 cells was decreased, the levels of anti-inflammatory factors IL-10 and TGF-β were increased, and levels of pro-inflammatory factors IL-17, IL-21 and IL-22 were decreased in chronic hepatitis B patients combined with thrombocytopenia, indicating the decreased autoimmune response and improved thrombocytopenia. The changes were closely related to the complete response.

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

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

Relationship of Treg/Th17 balance with HBeAg change in HBeAg-positive chronic hepatitis B patients receiving telbivudine antiviral treatment: A longitudinal observational study

Telbivudine (LdT) is an orally L-nucleoside with potent and specific antihepatitis B virus (HBV) activity. The higher rate of hepatitis B e antigen (HBeAg) seroconversion of LdT treatment than other anti-HBV agents suggests a potential immunomodulatory effect. The aim of the study was to investigate the changes of regulatory T cell (Treg)/interleukin (IL)-17-producing CD4+T helper (Th17) balance during LdT treatment and to discuss the relationship of Treg/Th17 balance with HBeAg change in HBeAg-positive chronic hepatitis B (CHB) patients receiving LdT antiviral treatment. Twenty-seven HBeAg-positive CHB patients received LdT for 24 weeks and the percentages of Tregs and cells (Th17 cells) in peripheral blood as well as the serum TGF-β1 and IL-17 levels in these patients were longitudinally analyzed. We found that the frequencies of Tregs and Th17 cells in peripheral blood as well as the serum TGF-β1 and IL-17 levels increased significantly in CHB patients compared with healthy controls. During the LdT treatment, the Tregs frequency and TGF-β1 level tended to decrease, and Th17 cells frequency and IL-17 level showed a reverse "V"-type change. The frequency of Tregs and the ratio of Treg/Th17 were significantly lower in the HBeAg loss group than those in the HBeAg no-loss group at the baseline. More important, the Tregs frequency and TGF-β1 level were both positively correlated with HBeAg level during the LdT treatment for 24 weeks. Our data suggest that the lower Tregs frequency and Treg/Th17 ratio at the baseline of LdT treatment, the more likely to get the HBeAg loss. HBeAg negative can be predicted using changes in Tregs frequency and TGF-β1 level during LdT treatment in CHB patients. Maybe we could provide the immunology marker for exploring the mechanism of the higher HBeAg seroconversion rate of LdT therapy.

Immune Regulation by T Regulatory Cells in Hepatitis B Virus-Related Inflammation and Cancer

Hepatocellular carcinoma (HCC) is the leading cause of cancer death, and hepatitis B virus (HBV) infection is one of the commonest causes in Asian countries. India has the second largest pool after China for hepatitis B-infected subjects. HBV clearance is T cell dependent, and one of the reasons for T cells hyporesponsiveness is due to mass production of regulatory T cells (Tregs) through activation of Notch signalling, which suppress CD4/CD8 T cells. Tregs are important to maintain cellular homoeostasis; however, during viral infection increase of Tregs is inversely proportional to HBV DNA titres. Tregs exert their suppressive effect either via cell-to-cell contact or through release of interleukin (IL)-2, IL-10, TGF-β and IL-35. In Chronic hepatitis B virus CHBV infection, PD-1 pathway also gets activated and is involved in promoting tolerance. However, with Tregs induction, virus-specific T cell responses also get decreased. Circulatory and intratumoural Tregs promote development of HBV-specific HCC more by decreasing and impairing the effector functions of CD8 T cells. Antiviral therapies and PD-1 blockade strategy had shown the inhibition of Tregs and reduction in HBV DNA. However, inhibition of HBV-specific Tregs is major challenge for future therapies. New cytokine blockade therapies have emerged as potential therapeutic potentials.

Deregulation of Regulatory T Cells in Acute-on-Chronic Liver Failure: A Rat Model

Aims. Acute-on-chronic liver failure (ACLF) and acute liver failure (ALF) are similar in many respects during their acute exacerbation; however, ACLF generally has a poorer prognosis. We aimed to investigate the role and dynamic changes of regulatory T cell (Treg) and T helper 17 (Th17) cell proportions during ACLF progress. Methods. All rats were classified into two groups randomly: ACLF group and ALF group (control group). The rat model of ACLF was preestablished by intraperitoneal injection of carbon tetrachloride for 2 months. Then acute liver injury was induced by combined D-galactosamine and lipopolysaccharide. Six time points were examined before or after acute induction. Liver samples were performed with hematoxylin-eosin and Masson staining; circulatory Treg and Th17 cell frequencies were determined using flow cytometry assays; serum levels of alanine aminotransferase, aspartate aminotransferase, interleukin-10 (IL-10), and interferon-γ (IFN-γ) were examined. Results. In group ACLF, both Th17 cell proportion and IFN-γ level presented upgrade firstly and then descend latter tendency; the trends of Treg cell proportion and IL-10 level were observed to gradually decrease and became stable. Conclusion. The Treg cells played an important role in the immunologic mechanism during the process of ACLF. And the function of Treg cells in ACLF was defective.

Slow reduction of IP-10 Levels predicts HBeAg seroconversion in chronic hepatitis B patients with 5 years of entecavir treatment

The aim of this study was to determine the correlation between dynamic changes in serum cytokine/chemokine expression levels in response to entecavir (ETV) treatment and HBV e antigen (HBeAg) seroconversion in patients with chronic hepatitis B (CHB). Four cytokines (interleukin [IL]-4, IL-6, IL-8, and interferon-γ) and five chemokines (macro-phage inflammatory protein [MIP]-1α, MIP-1β, platelet derived growth factor-BB, and interferon-inducible protein 10 [IP-10]) before ETV therapy and at 3, 6, 12, 24, 36 and 60 months during therapy in 105 CHB patients were analyzed. The results showed that the low decrease rate of IP-10 levels after 1 year of ETV treatment was an independent predictor of HBeAg seroconversion at year 5 (Hazard ratio = 0.972). The area under the receiver operating characteristic curves for the decrease rate of IP-10 levels after 1 year of treatment to discriminate a year-5 HBeAg seroconversion was 0.752 (p = 0.005). The results indicate that higher IP-10 level at year one of ETV treatment is associated with an increased probability of HBeAg seroconversion. Quantification of IP-10 during ETV treatment may help to predict long-term HBeAg seroconversion in patients with CHB.

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.

Emerging roles of T helper 17 and regulatory T cells in lung cancer progression and metastasis

Lung cancer is a leading cause of cancer-related deaths worldwide. Lung cancer risk factors, including smoking and exposure to environmental carcinogens, have been linked to chronic inflammation. An integral feature of inflammation is the activation, expansion and infiltration of diverse immune cell types, including CD4⁺ T cells. Within this T cell subset are immunosuppressive regulatory T (Treg) cells and pro-inflammatory T helper 17 (Th17) cells that act in a fine balance to regulate appropriate adaptive immune responses.In the context of lung cancer, evidence suggests that Tregs promote metastasis and metastatic tumor foci development. Additionally, Th17 cells have been shown to be an integral component of the inflammatory milieu in the tumor microenvironment, and potentially involved in promoting distinct lung tumor phenotypes. Studies have shown that the composition of Tregs and Th17 cells are altered in the tumor microenvironment, and that these two CD4⁺ T cell subsets play active roles in promoting lung cancer progression and metastasis.We review current knowledge on the influence of Treg and Th17 cells on lung cancer tumorigenesis, progression, metastasis and prognosis. Furthermore, we discuss the potential biological and clinical implications of the balance among Treg/Th17 cells in the context of the lung tumor microenvironment and highlight the potential prognostic function and relationship to metastasis in lung cancer.

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

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

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.

Serum Interleukin (IL)-9 and IL-10, but not T-Helper 9 (Th9) Cells, are Associated With Survival of Patients With Acute-on-Chronic Hepatitis B Liver Failure

CD4 T helper (Th) cells are reported to be essential for initiating and maintaining an effective immune response to hepatitis B virus (HBV) infection. Th9 cells are a new subset of CD4 Th cells that produce interleukin (IL)-9 and IL-10. The present study aimed to investigate the percentage of Th9 cells relative to the number of CD4 cells in peripheral blood. We also measured serum IL-9 and IL-10 levels in different stages of HBV infection and their relationship with progress and prognosis of liver disease. Whole blood samples from 111 patients with HBV infection, including 39 chronic hepatitis B (CHB), 25 HBV-liver cirrhosis (HBV-LC), 21 acute-on-chronic liver failure (ACLF) patients, and 26 healthy controls were collected. The percentage of Th9 cells and serum IL-9 and IL-10 levels were determined. There was no significant difference in the percentage of Th9 cells and serum IL-9 and IL-10 levels among different groups, nor were these related to hepatitis B e antigen status, complications of cirrhosis, inflammation index, or prognosis indexes. There was no change in the percentage of Th9 cells before and after antiviral treatment in CHB patients. There was no correlation of Th9 cells with survival of ACLF patients. However, IL-9 and IL-10 levels were significantly higher in the nonsurvived ACLF patients compared to survived ACLF patients. Furthermore, baseline IL-9 level predicted the prognosis of ACLF patients with 87.5% sensitivity and 61.5% specificity.Thus, our data indicate that Th9 cells were unlikely involved in the pathogenesis of HBV infection, but elevation in IL-9 and IL-10 may signal poor prognosis for ACLF.

Upregulation of PD-1 on CD4⁺CD25⁺ T cells is associated with immunosuppression in liver of mice infected with Echinococcus multilocularis

Alveolar echinococcosis is a zoonotic disease caused by Echinococcus multilocularis (E. multilocularis) infection. The relationship between PD-1/PD-L1 pathway and Tregs at different stages of E. multilocularis infection has rarely been reported. This study aims to investigate the role of PD-1/PD-L1 in immunosuppression of Tregs in E. multilocularis infection. Hematoxylin-eosin staining, flow cytometry, immunohistochemistry, quantitative RT-PCR analysis, cytometric bead array and MTT assay were used to analyze liver pathological changes, percentages of PD-1(+) Tregs and PD-L1(+) dendritic cells (DCs), expression levels of PD-1, PD-L1 and Foxp3, levels of interleukin-10 (IL-10) and transforming growth factor beta (TGF-β) and proliferation of lymphocytes. During middle-late stage (day 30 to day 330) the percentages of PD-1(+) Tregs and PD-L1(+) DCs together with levels of Foxp3, IL-10 and TGF-β increased significantly and maintained at high level. The expression of PD-1 and PD-L1 was increased with the enlarging erosion of E. multilocularis, and was mainly distributed in hepatic sinus, fibrous wall of alveolar hydatid and germinal layer around foci of infection. PD-1/PD-L1 promoted the secretion of IL-10 and TGF-β. Our results indicate that engagement of the PD-1 and PD-L1 correlates with inhibition of T-cell effector function, cytokine secretion and proliferation. High expression of PD-1/PD-L1 may play an important role in stimulating CD4(+)CD25(+) T cells, and maintaining peripheral tolerance and immune evasion during chronic infection of E. multilocularis.

Hepatic serum amyloid A1 aggravates T cell-mediated hepatitis by inducing chemokines via Toll-like receptor 2 in mice

Serum amyloid A is a proinflammatory molecule that induces leukocyte infiltration and promotes neutrophil adhesion to endothelial cells under inflammatory conditions. The aim of this study was to examine whether Saa1 aggravates T cell-mediated hepatitis by inducing chemokines in a liver-specific, Saa1-overexpressing, transgenic (TG) mouse model. We generated TG mice in which Saa1 was overexpressed specifically in liver tissue. The chemokines monocyte chemotactic protein 1 (MCP1), MIP1α, MIP1β, interferon γ-induced protein 10 (IP-10), and eotaxin were induced in Saa1 TG mice. After concanavalin A treatment, Saa1 expression was higher in Saa1 TG mice than in WT mice. More severe liver injury, increased hepatocyte apoptosis, and higher levels of hepatic enzymes were observed in Saa1 TG mice than in WT mice. Liver infiltration of CD4(+) T cells and macrophages increased after inducing hepatitis. Activation of T cells was higher in Saa1 TG mice than in WT mice, and the populations of Th17 cells and regulatory T cells were altered by overexpressing Saa1 in TG mice. Secretion of various cytokines, such as interferon γ, tumor necrosis factor α, and interleukin 6, increased in Saa1 TG mice. Injecting a Toll-like receptor 2 (TLR2) antagonist in vivo inhibited chemokine expression and IκBα phosphorylation and showed that the induction of chemokines by Saa1 was dependent on TLR2. Hepatic Saa1 accelerated T cell-mediated hepatitis by inducing chemokine production and activating T cells by TLR2. Therefore, Saa1 might be a novel inflammatory factor that acts as a chemokine modulator in hepatitis.

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

Pegylated interferon and ribavirin combination therapy is known to be effective in suppressing viral replication in 50-60% of hepatitis C virus (HCV)-infected patients. However, HCV-infected patients often exhibit varied responses to therapy. Therefore, the identification of immunological markers associated with the clinical outcomes of antiviral treatment is critical for improvement of therapeutic options. In this study, we aimed to investigate the ratio of CD4(+) CD25(+) FoxP3(+) regulatory T (Treg) cells to interleukin-17A (IL-17A) -producing T helper type 17 (Th17) cells, and its association with clinical outcomes in response to anti-HCV treatment. In all, 114 patients with HCV infection received pegylated interferon-α2a and ribavirin therapy for 48 weeks, and the frequency of Treg cells and Th17 cells as well as the levels of secreted cytokines were longitudinally analysed by flow cytometry and ELISA. Treg cell proportions and IL-10 production were significantly elevated in HCV-infected patients, especially for HCV genotype 1b. However, the frequency of Th17 cells as well as the secretion of IL-17, IL-22 and IL-23 did not reveal notable difference between HCV infections and healthy individuals. Inhibition of HCV replication was accompanied by a reduction in Treg cells, but little influence on Th17 cells, which led to a significant decrease in Treg : Th17 ratios. Skewed Treg : Th17 ratios existed in chronic hepatitis C. HCV RNA load is closely associated with Treg : Th17 ratios during pegylated interferon-α2a and ribavirin treatment in HCV-infected patients. The imbalance of Treg cells to Th17 cells might play an important role in persistent HCV infection.

Over-expression of Roquin aggravates T cell mediated hepatitis in transgenic mice using T cell specific promoter

Chronic hepatitis is a major cause of liver cancer, so earlier treatment of hepatitis might be reducing liver cancer incidence. Hepatitis can be induced in mice by treatment with Concanavalin A (Con A); the resulting liver injury causes significant CD4(+) T cell activation and infiltration. In these T cells, Roquin, a ring-type E3 ubiquitin ligase, is activated. To investigate the role of Roquin, we examined Con A-induced liver injury and T cell infiltration in transgenic (Tg) mice overexpressing Roquin specifically in T cells. In Roquin Tg mice, Con A treatment caused greater increases in both the levels of liver injury enzymes and liver tissue apoptosis, as revealed by TUNEL and H&E staining, than wild type (WT) mice. Further, Roquin Tg mice respond to Con A treatment with greater increases in the T cell population, particularly Th17 cells, though Treg cell counts are lower. Roquin overexpression also enhances increases in pro-inflammatory cytokines, including IFN-γ, TNF-α and IL-6, upon liver injury. Furthermore, Roquin regulates the immune response and apoptosis in Con A induced hepatitis via STATs, Bax and Bcl2. These findings suggest that over-expression of Roquin exacerbates T-cell mediated hepatitis.

Ratios of regulatory T cells/T-helper 17 cells and transforming growth factor-β1/interleukin-17 to be associated with the development of hepatitis B virus-associated liver cirrhosis

BACKGROUND AND AIM

The aim of this study is to evaluate the association of the regulatory T cells (Treg)/T-helper (Th) 17 cells and transforming growth factor-β1 (TGF-β1)/interleukin-17 (IL-17) ratios with the survival and disease progression in patients with hepatitis B virus (HBV)-associated liver cirrhosis (LC).

METHODS

The frequencies of Treg and Th17 cells were analyzed in 28 patients with HBV-LC, 70 patients with chronic hepatitis B (CHB) and 20 normal controls (NC) by flow cytometry. The levels of cytokines related to Treg/Th17 differentiation, including IL-10, TGF-β1, IL-17, and IL-23, were measured by ELISA.

RESULTS

Compared with NC, Treg cells were significantly increased in CHB patients and slightly increased in HBV-LC patients, whereas Th17 cells were markedly increased both in patients with CHB and HBV-LC. HBV-LC patients, especially the nonsurvival ones, manifested a profound decrease in the Treg/Th17 ratio, which was negatively correlated with Child-Pugh and model of end-stage liver disease scores. Serum IL-10, TGF-β1, IL-17, and IL-23 levels were all significantly higher in HBV-LC patients than in NC. In addition, the TGF-β1/IL-17 ratio was also markedly increased in patients with HBV-LC, especially in nonsurvival and decompensated liver cirrhosis patients, and positively correlated with total bilirubin, Child-Pugh, and model of end-stage liver disease scores.

CONCLUSIONS

The decreased Treg/Th17 ratio and increased TGF-β1/IL-17 ratio may be associated with the survival and disease progression in HBV-LC patients, and both of the two ratios can be used independently to predict the prognosis and disease progression of HBV-LC patients.

Dynamic Changes of Treg and Th17 Cells and Related Cytokines Closely Correlate With the Virological and Biochemical Response in Chronic Hepatitis B Patients Undergoing Nucleos(t)ide Analogues Treatment

BACKGROUND

The restoration of HBV-specific T-cell response during antiviral therapy is associated with CD4+T-cell activity. Treg cells and Th17 cells are subtypes of CD4+T cell. However, it has remained unknown how the Treg and Th17 cells and their associated cytokines affect nucleos(t)ide analogues (NA) antiviral efficacy.

OBJECTIVES

The aim of the present study was to provide a new insight to evaluate the NA antiviral therapy for patients with chronic hepatitis B (CHB).

PATIENTS AND METHODS

Forty-four CHB patients hospitalized between July 2010 and August 2011 were enrolled in this study. They were received NA (entecavir, lamivudine and adefovir) treatment for 14.42 ± 13.08 weeks, and the peripheral blood was collected. The frequencies of Treg and Th17 cells were detected by flow cytometric analysis, and the levels of IL-10, TGF-β1, IL-17 and IL-23 were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

In complete and partial-responders, Treg cells frequencies and IL-10, TGF-β1, IL-23 levels were all decreased significantly after NA therapy, while Th17 cells and the IL-17 levels were increased slightly. Treg/Th17 ratio was only dramatically declined in complete-responders. But there was no significant difference in non-responders. Either HBV DNA decreased by at least 2 log copies /mL or ALT turned to normal level, Treg cells frequencies and IL-10, TGF-β1, IL-23 levels were significantly reduced. Meanwhile, Treg cells were positively correlated with HBV DNA and ALT.

CONCLUSIONS

The changes of Treg and Th17 cells and their associated cytokines were related to virological and biochemical responses.

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.