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

Interleukin-35 Enhances Regulatory T Cell Function by Potentially Suppressing Their Transdifferentiation into a T Helper 17-Like Phenotype in Kawasaki Disease

Interleukin-35 (IL-35) modulates immune cell activity in inflammation and autoimmune disorders. However, its specific effects on regulatory T cells (Tregs) in Kawasaki disease remain ambiguous. We enrolled 37 patients with Kawasaki disease and 20 healthy controls in this study. The percentages of CD4⁺CD25⁺CD127^dim/- Tregs and CD4⁺IL-17A⁺ T helper 17 (Th17) cells were determined via flow cytometry. Tregs were enriched and stimulated by recombinant IL-35. Immunosuppressive activity of Tregs was via co-culture with autologous CD4⁺CD25^- T cells. Purified Tregs were cultured for Th17 polarization, and the influence of IL-35 on Tregs transdifferentiation into a Th17-like phenotype was determined. The percentage of Tregs was elevated in patients with Kawasaki disease and positively correlated with C-reactive protein levels. There was no significant difference in the percentage of Th17 cells between the two groups. IL-35 stimulation increased the percentage of Tregs in both groups, but decreased the percentage of Tregs Th17 cells in affected patients. IL-35 enhanced the immunosuppressive activity of Tregs in both groups, resulting in decreased cellular proliferation and increased IL-35 subunit mRNA relative levels in co-culture system. IL-35 did not affect the immune checkpoint molecule expression in Tregs, but inhibited the transdifferentiation of Tregs into a Th17-like phenotype in affected patients, indicating by the down-regulations of C-C motif chemokine receptor-4/6 expression, retinoid-related orphan nuclear receptor γt mRNA levels, and IL-17 secretion. IL-35 contributes to the immunosuppressive function of Tregs by inhibiting the cellular proliferation and transdifferentiation of Tregs into a Th17-like phenotype, which may be a protective mechanism against Kawasaki disease.

Interleukin-35 has a Protective Role in Infectious Mononucleosis-Induced Liver Inflammation Probably by Inhibiting CD8+ T Cell Function

Interleukin (IL)-35 plays an immunosuppressive role in infectious diseases, autoimmune disorders, and cancers. However, IL-35 expression and its regulation of CD8⁺ T cells in infectious mononucleosis (IM) are not fully understood. In this study, three groups of participants were compared, including twenty-three patients of IM without liver inflammation, twenty-eight patients of IM with liver inflammation, and twenty-one controls. Plasma and peripheral blood mononuclear cells (PBMCs) were isolated. CD8⁺ T cells were purified. Plasma IL-35 was measured by ELISA. PBMCs and CD8⁺ T cells were stimulated with recombinant human IL-35 in vitro. Perforin and granzyme B secretion was assessed by ELISPOT. Immune checkpoint molecule expression was investigated by flow cytometry. CD8⁺ T cells were co-cultured with HepG2 cells in direct contact and indirect contact manner. The cytotoxicity of CD8⁺ T cells was calculated by measuring lactate dehydrogenase release and proinflammatory cytokine expression. There was no significant difference in plasma IL-35 levels between patients with IM without liver inflammation and the controls, but the IL-35 level was notably increased in patients with IM who presented with liver inflammation and negatively correlated with aminotransferase. CD8⁺ T cells in patients with IM with liver inflammation showed stronger cytotoxicity. IL-35 stimulation inhibited CD8⁺ T cell-induced target cell death in patients with IM, mainly through suppression of IFN-γ/TNF-α secretion and elevation of immune checkpoint molecule expression, but did not affect perforin or granzyme B secretion. The current data indicated that IL-35 dampened the cytotoxicity of CD8⁺ T cells in patients with IM probably via repression of cytokine secretion. Elevated IL-35 may protect against CD8⁺ T cell-induced liver inflammation in patients with IM.

TAR DNA-Binding Protein 43 is Cleaved by the Protease 3C of Enterovirus A71

Enterovirus A71 (EV-A71) is one of the etiological pathogens leading to hand, foot, and mouth disease (HFMD), which can cause severe neurological complications. The neuropathogenesis of EV-A71 infection is not well understood. The mislocalization and aggregation of TAR DNA-binding protein 43 (TDP-43) is the pathological hallmark of amyotrophic lateral sclerosis (ALS). However, whether TDP-43 was impacted by EV-A71 infection is unknown. This study demonstrated that TDP-43 was cleaved during EV-A71 infection. The cleavage of TDP-43 requires EV-A71 replication rather than the activated caspases due to viral infection. TDP-43 is cleaved by viral protease 3C between the residues 331Q and 332S, while mutated TDP-43 (Q331A) was not cleaved. In addition, mutated 3C which lacks the protease activity failed to induce TDP-43 cleavage. We also found that TDP-43 was translocated from the nucleus to the cytoplasm, and the mislocalization of TDP-43 was induced by viral protease 2A rather than 3C. Taken together, we demonstrated that TDP-43 was cleaved by viral protease and translocated to the cytoplasm during EV-A71 infection, implicating the possible involvement of TDP-43 in the pathogenesis of EV-A71infection.

Abnormalities of ILC1 in children with hand, foot and mouth disease during enterovirus 71 infection

Children with HFMD due to EV71 infection are more likely to suffer from neurogenic complications, leading to higher morbidity and mortality. ILCs play crucial roles in the initiation of host immunity. However, the contribution of ILCs to the occurrence and development of HFMD due to EV71 infection remains to be explored. The results of our study showed that the levels of peripheral ILC1s and Th1 cells were increased in children with severe HFMD compared to healthy children, as were ILC1- and Th1-related cytokines and transcription factors. Furthermore, HFMD children with a higher frequency of circulating ILC1s exhibited a 2.9-fold greater risk of severity when HFMD was accompanied by VEM. Our study is the first to show that ILC1 abnormalities contribute to the pathogenesis of the severity of HFMD, in which ILC1s are aberrant increased and affect the cellular and humoral immunity. ILC1s could be used in the diagnosis of HFMD.

Predicting Severe Enterovirus 71-Infected Hand, Foot, and Mouth Disease: Cytokines and Chemokines

Enterovirus 71 (EV71) is one of the most common intestinal virus that causes hand, foot, and mouth disease (HFMD) in infants and young children (mostly ≤5 years of age). Generally, children with EV71-infected HFMD have mild symptoms that resolve spontaneously within 7-14 days without complications. However, some EV71-infected HFMD cases lead to severe complications such as aseptic meningitis, encephalitis, acute flaccid paralysis, pulmonary edema, cardiorespiratory complication, circulatory disorders, poliomyelitis-like paralysis, myocarditis, meningoencephalitis, neonatal sepsis, and even death. The mechanism of EV71 pathogenesis has been studied extensively, and the regulation of host immune responses is suspected to aggravate EV71-induced severe complications. Recently, several cytokines or chemokines such as TNF-α, IFN-γ, IL-1β, IL-18, IL-33, IL-37, IL-4, IL-13, IL-6, IL-12, IL-23, IL-27, IL-35, IL-10, IL-22, IL-17F, IL-8, IP-10, MCP-1, G-CSF, and HMGB1 have been reported to be associated with severe EV71 infection by numerous research teams, including our own. This review is aimed at summarizing the pathophysiology of the cytokines and chemokines with severe EV71 infection.

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.

Prenatal exposure to perfluoroalkyl substances is associated with lower hand, foot and mouth disease viruses antibody response in infancy: Findings from the Guangzhou Birth Cohort Study

BACKGROUND

Perfluoroalkyl substances (PFASs) are synthetic chemicals widely used in industry and for commercial products. Their immunomodulatory effects are a growing health concern in children. Hand, Foot and Mouth Disease (HFMD) is a common childhood viral infection, and increased incidence of which has parallel the rise in PFAS exposure in the Asia-Pacific region.

OBJECTIVE

We conducted the first study to assess whether prenatal exposure to PFAS was associated with a reduction in HFMD virus antibodies in infants.

METHODS

We enrolled 201 mother-infant pairs from the Guangzhou Birth Cohort Study from July to October 2013. High performance liquid chromatography-mass spectrometry was employed to determine concentrations of specific PFAS isomers in cord blood. Neutralizing antibodies titers were measured against two HFMD viruses, enterovirus 71 (EV71) and coxsackievirus A 16 (CA16), in cord blood serum and blood serum at three months of age.

RESULTS

Higher umbilical cord blood PFAS concentrations were associated with lower EV71 and CA16 antibody concentrations. A doubling in the composite sum of cord blood PFASs in three month old infants was associated with significant increase in the risk of HFMD antibody concentration below clinical protection level (≥1:8 titers) for CA16 (odds ratio, OR: 2.74 [95% confidence interval (CI): 1.33, 5.61] and for EV71 (OR = 4.55, 95% CI: 1.45, 4.28). This association was higher in boys at three months of age for CA16.

CONCLUSIONS

Our findings suggest that cord blood PFAS exposure is associated with lower HFMD antibody in infancy. Given the widespread nature of PFAS exposures and the high global incidence of HFMD globally, these findings have substantial public health implications and therefore, these associations need to be replicated in a larger study to more definitively address the risk.

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.

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.

Crosstalk between Toll-like receptor 3 and Notch signaling contributes to CD14+ monocytes activity in enterovirus 71 infected hand, foot, and mouth disease

Interaction between Toll-like receptor (TLR) and Notch signaling contributes to inflammatory response in nephropathy and fungicidal infection, however, the role of this crosstalk remains not fully elucidated in enterovirus 71 (EV71)-induced hand, foot, and mouth disease (HFMD). The aim of this study was to investigate the crosstalk between TLR and Notch in inflammatory regulation in EV71 infection. Thirty-seven EV-71-indcued HFMD (16 mild and 21 severe cases) and eleven normal control (NC) were enrolled. CD14⁺ monocytes were purified, and were stimulated with either TLR3/4 agonists [poly(I: C) or LPS] or Notch signaling inhibitor. TLRs and Notch receptors expression, proinflammatory cytokines production, and important molecules in signaling pathways were measured by real-time PCR, ELISA, and Western blot. TLR3 and TLR4 was significantly elevated in CD14⁺ monocytes from HFMD patients than NC. Notch1 and Notch2 mRNA was also remarkably increased in CD14⁺ monocytes from severe HFMD. Poly(I: C) stimulation resulted in robust increase of IL-8, IL-6, and TNF-α by CD14⁺ monocytes in severe HFMD compared to NC. Activation of Notch1, Notch2, and target genes, Hes1 and Hes5 was also enhanced upon ploy(I: C) treatment. Although inhibition of Notch signaling did not affect TLR3 expression, poly(I: C)-induced inflammatory response was robustly attenuated, which was accompanied by silencing Src phosphorylation in CD14⁺ monocytes from severe HFMD patients. The current data indicated that crosstalk between TLR3 and Notch signaling modulated CD14⁺ monocytes function and inflammatory responses in the progression of EV71-induced HFMD.