Regulates Th17 Cell Differentiation Research Articles

Autotaxin-Lysophosphatidic Acid Axis Blockade Improves Inflammation by Regulating Th17 Cell Differentiation in DSS-Induced Chronic Colitis Mice.

Autotaxin-lysophosphatidic acid (ATX-LPA) axis is closely associated with several inflammation-related diseases. In the colonic mucosa of patients with chronic ulcerative colitis (UC), the expression of ATX and the percentage of Th17 cells are found to increase. However, it is unclear whether ATX-LPA axis affects the differentiation of Th17 cells in chronic UC. To investigate whether ATX-LPA axis contributes to Th17 cell differentiation, a mouse model of chronic UC was established by drinking water with DSS at intervals. ATX inhibitor was used as an intervention. The disease active index (DAI), colonic weight to length ratio, colon length, colon histopathology, and MAdCAM-1 were observed. Additionally, the expression of ATX, LPA receptor, CD34, IL-17A, IL-21, IL-6, ROR-γt, STAT3 in colonic tissue, and the percentage of Th17 cells in spleens and mesenteric lymph nodes (MLNs) were measured using different methods. ATX blockade was able to relieve symptoms and inflammatory response of DSS-induced chronic colitis. The DAI and colonic weight to length ratio were apparently decreased, while the colon length was increased. The pathological damage and colitis severity were lighter in the inhibitor group than that in the DSS group. Inhibiting ATX reduced the expression of ATX, LPA receptor, and CD34 and also decreased the percentages of Th17 cells in spleens and MLNs and the expressions of IL-17A and IL-21, as well as the factors in Th17 cell signaling pathway including IL-6, ROR-γt, and STAT3 in colonic tissue. ATX-LPA axis blockade could alleviate inflammation by suppressing Th17 cell differentiation in chronic UC.

Quantitative Proteomics Reveals the Dynamic Protein Landscape during Initiation of Human Th17 Cell Polarization

SummaryTh17 cells contribute to the pathogenesis of inflammatory and autoimmune diseases and cancer. To reveal the Th17 cell-specific proteomic signature regulating Th17 cell differentiation and function in humans, we used a label-free mass spectrometry-based approach. Furthermore, a comprehensive analysis of the proteome and transcriptome of cells during human Th17 differentiation revealed a high degree of overlap between the datasets. However, when compared with corresponding published mouse data, we found very limited overlap between the proteins differentially regulated in response to Th17 differentiation. Validations were made for a panel of selected proteins with known and unknown functions. Finally, using RNA interference, we showed that SATB1 negatively regulates human Th17 cell differentiation. Overall, the current study illustrates a comprehensive picture of the global protein landscape during early human Th17 cell differentiation. Poor overlap with mouse data underlines the importance of human studies for translational research.

PPARα suppresses Th17 cell differentiation through IL-6/STAT3/RORγt pathway in experimental autoimmune myocarditis

Family members of peroxisome proliferator-activated receptors (PPARs), such as PPARγ, have been shown to be effective in regulating T helper 17 (Th17) cell differentiation. However, whether PPARα, another important family member of PPARs, contributes to Th17 cell differentiation remains controversial. In the present study, we show that PPARα may be a negative regulator of Th17 cell differentiation. In CD4+ T cells from PPARα knockout mice, PPARα deficiency enhances IL-17 and IL-6 levels and promotes Th17 cell differentiation. In contrast, in CD4+ T cells from wild type mice, PPARα activation suppresses Th17 cell differentiation. Furthermore, IL-6 neutralizing antibody dose-dependently reduces the activity of STAT3 and down-regulates the protein expression of RORγt in CD4+ T cells from PPARα knockout mice but has no effect on that of wild type mice. On the other hand, in isolated CD4+ T cells from experimental autoimmune myocarditis (EAM) rats, PPARα agonist Fenofibrate decreased the expression of IL-17 and RORγt, increased the expression of Foxp3, while PPARα antagonist MK886 reversed these effects. Importantly, in vivo activation of PPARα ameliorates EAM by suppressing Th17 cell differentiation through reducing the expression of RORγt and phosphorylated STAT3 that are upregulated in EAM hearts. These results imply that PPARα suppresses Th17 cell differentiation through IL-6/STAT3/RORγt signaling pathway and suggest that PPARα may become a molecular target for treating autoimmune myocarditis.

Critical regulation of Th17 cell differentiation by serum amyloid-A signalling in Behcet’s disease

The current understandings on cellular and molecular biology suggest that Th17 axis plays a pivotal role in Behcet’s disease (BD) pathogenesis. Recently the role of serum amyloid-A (SAA) as a potential marker of disease activity in BD patients has been explored, and it has been reported that the occurrence of specific clinical features are significantly associated with high serum levels of this inflammatory mediator. The aim of this study was to investigate the cytokine-like activity of SAA in inducing Th17 differentiation from CD4 + T naive cells in BD. Purified peripheral monocytes from BD and healthy control (HC) were stimulated with SAA “in vitro”, and secreted IL-8, TNF-α, IL-18, IFN-α, IFN-γ, IL-1β and IL-6 were measured using a Bio-Rad multiplex cytokine immunoassay. To assess Th17 differentiation, purified CD4 + T cells were challenged with anti-CD3/CD28 antibodies, while cultured with supernatant derived from SAA stimulated monocytes, and intracellular staining of IL-17A and IFN-γ was evaluated by flow-cytometry. Furthermore, peripheral blood mononuclear cells (PBMCs) were stimulated with SAA and transcript levels of RAR-related orphan nuclear receptor (ROR)–γt and IL-17A were assessed by Real-time PCR. Upon stimulation with SAA, monocytes obtained from both HC and BD groups released large amounts of IL-8, IL-6, TNF-α, IL-1β and IFN-α. Monocytes-derived supernatants from BD patients, but not HC, were capable of promoting Th17 but not Th1 differentiation from CD4 + T cells. However, SAA did not induce up-regulation of Th17 specific mRNA transcript such as IL-17A and (ROR)–γt in PBMCs from both HC and BD. In BD patients SAA induced Th17 polarization rather than Th1 differentiation from CD4 + T cells. These data suggest that a critical regulation of Th17 may be the functional link between acute SAA increase and the induction of Th17 mediated inflammatory response in BD.

MBD2 regulates differentiation and function of Th17 cells in neutrophils- dominant asthma via HIF-1\u03b1

BackgroundT helper 17 (Th17) cells have proven to be crucial in the pathogenesis of neutrophils-dominant asthma. Hypoxia inducible factor-1α (HIF-1α) is involved in allergic responses in asthma. Our previous studies indicated that Methtyl-CpG binding domain protein 2 (MBD2) expression was increased in asthma patients. The aim of the present study is to understand how MBD2 interacts with HIF-1α to regulate Th17 cell differentiation and IL-17 expression in neutrophils-dominant asthma.MethodsA neutrophils-dominant asthma mouse model was established using female C57BL/6 mice to investigate Th17 cell differentiation and MBD2 and HIF-1α expression regulation using flow cytometry, western blot or qRT-PCR. MBD2 and HIF-1α genes were silenced or overexpressed through lentiviral transduction to explore the roles of MBD2 in Th17 cell differentiation and IL-17 release in neutrophils-dominant asthma.ResultsA neutrophilic inflammatory asthma phenotype model was established successfully. This was characterized by airway hyperresponsiveness (AHR), increased BALF neutrophil granulocytes, activated Th17 cell differentiation, and high IL-17 levels. MBD2 and HIF-1α expression were significantly increased in the lung and spleen cells of mice with neutrophils-dominant asthma. Through overexpression or silencing of MBD2 and HIF-1α genes, we have concluded that MBD2 and HIF-1α regulate Th17 cell differentiation and IL-17 secretion. Moreover, MBD2 was also found to regulate HIF-1α expression.ConclusionsOur findings have uncovered new roles for MBD2 and HIF-1α, and provide novel insights into the epigenetic regulation of neutrophils-dominant asthma.

MBD2-mediated Th17 differentiation in severe asthma is associated with impaired SOCS3 expression

T helper 17 (Th17) cells has proven to be crucial in the pathogenesis of severe asthma. Although it is known that Suppressor of cytokine signaling 3 (SOCS3) is involved in differentiation of Th17 cells but, how it affects severe asthma is uncertain. Since previous studies indicated that Methtyl-CpG binding domain protein 2 (MBD2) null mice was deficient in Th17 cell differentiation, the aim of the present study was to understand how MBD2 interacts with SOCS3 to regulate Th17 cell differentiation in severe asthma. Here, we show that SOCS3 expression was significantly decreased in Th17-mediated severe asthmatic mice, accompanied by elevated STAT3 phosphorylation and RORγt expression. Knock-down of SOCS3 promoted the differentiation of naïve T cells into Th17 cells through STAT3/RORγt pathway. Meanwhile, MBD2 was overexpressed in Th17-mediated severe asthmatic mice. Intervention of MBD2 expression lead to a negative change of SOCS3 expression, whereas the differentiation of Th17 cells showed positive change. In addition, MBD2 knockout (MBD2-KO) mice displayed increased SOCS3 expression and decreased Th17 differentiation after severe asthma modeling. Taken together, our results suggest that MBD2 might facilitate Th17 cell differentiation via down-regulating SOCS3 expression in severe asthma. These findings uncover new roles for SOCS3 and MBD2, and provide a potential target for treatment of severe asthma.

Cytokine Regulation in Human CD4 T Cells by the Aryl Hydrocarbon Receptor and Gq-Coupled Receptors

Th17 cells contribute to host defense on mucosal surfaces but also provoke autoimmune diseases when directed against self-antigens. Identifying therapeutic targets that regulate Th17 cell differentiation and/or cytokine production has considerable value. Here, we study the aryl hydrocarbon receptor (AhR)-dependent transcriptome in human CD4 T cells treated with Th17-inducing cytokines. We show that the AhR reciprocally regulates IL-17 and IL-22 production in human CD4 T cells. Global gene expression analysis revealed that AhR ligation decreased IL21 expression, correlating with delayed upregulation of RORC during culture with Th17-inducing cytokines. Several of the AhR-dependent genes have known roles in cellular assembly, organization, development, growth and proliferation. We further show that expression of GPR15, GPR55 and GPR68 positively correlates with IL-22 production in the presence of the AhR agonist FICZ. Activation of GPR68 with the lorazepam derivative ogerin resulted in suppression of IL-22 and IL-10 secretion by T cells, with no effect on IL-17. Under neutral Th0 conditions, ogerin and the Gq/11 receptor inhibitor YM254890 blunted IL-22 induction by FICZ. These data reveal the AhR-dependent transcriptome in human CD4 T cells and suggest the mechanism through which the AhR regulates T cell function may be partially dependent on Gq-coupled receptors including GPR68.

Cytokine regulation in human CD4 T cells by the Aryl Hydrocarbon Receptor and GPR68

Abstract Th17 cells contribute to host defense on mucosal surfaces but also provoke autoimmune diseases when directed against self-antigens. Identifying therapeutic targets that regulate Th17 cell differentiation and/or cytokine production has considerable value. Here, we study the aryl hydrocarbon receptor (AhR)-dependent transcriptome in human CD4 T cells treated with Th17-inducing cytokines. We show that the AhR reciprocally regulates IL-17 and IL-22 production in human CD4 T cells. Global gene expression analysis revealed that AhR ligation decreased IL21 expression, correlating with delayed upregulation of RORC during culture with Th17-inducing cytokines. We further show that expression of GPR15, GPR55 and GPR68 positively correlates with IL-22 production in the presence of the AhR agonist FICZ. Activation of GPR68 with the lorazepam-derivative ogerin resulted in suppression of IL-22 and IL-10 secretion by T cells, with no effect on IL-17. These data reveal a novel feedback inhibitory pathway on IL-22 and IL-10 production in the presence of AhR agonists.

Regulation of Pathogenic T Helper 17 Cell Differentiation by Steroid Receptor Coactivator-3

T helper 17 (Th17) cell development is programmed by the orphan nuclear receptor RORγt, but the underlying mechanism is not well understood. Nuclear receptor-mediated transcriptional activation depends on coactivators. Here, we show that steroid receptor coactivator-3 (SRC-3) critically regulates Th17 cell differentiation. Reduced incidence of experimental autoimmune encephalitis (EAE) associated with decreased Th17 cell generation invivo wasobserved in mice with SRC-3 deletion specifically in Tcells. Invitro, SRC-3 deficiency did not affect TGF-β/IL-6-induced Th17 cell generation but severely impaired pathogenic Th17 differentiation induced by IL-1/IL-6/IL-23. Microarray analysis revealed that SRC-3 not only regulates IL-17A but also IL-1R1 expression. SRC-3 bound to Il17a and Il1r1 loci in a RORγt-dependent manner and was required for recruitment of the p300 acetyltransferase. Thus, SRC-3 is critical for RORγt-dependent gene expression in Th17 cell-driven autoimmune diseases.

DDIT4 and Associated lncDDIT4 Modulate Th17 Differentiation through the DDIT4/TSC/mTOR Pathway.

Inflammation that complicates many autoimmune diseases, such as multiple sclerosis (MS), has been correlated to abnormal differentiation of Th17 cells. However, the reasons that promote Th17 cell-driven autoimmunity are yet to be discovered. In this study, we sought evidence that DNA-damage-inducible transcript 4 (DDIT4) and its associated long noncoding RNA DDIT4 (lncDDIT4) inhibit Th17 cell differentiation. We recruited 36 patients. Six MS patients and five healthy volunteers (controls) contributed PBMCs as material for microarray analysis. Microarray assays of lncDDIT4 and DDIT4 RNA expression identified outstanding differences between MS and control subjects, which were verified with real-time quantitative PCR. We then interrupted the expression of lncDDIT4 and DDIT4 mRNA in MS patients' naive CD4+ T cells and observed the resulting changes in Th17 cells. The expression of lncDDIT4 and DDIT4 mRNA were higher both in PBMCs and CD4+ T cells of MS patients than in healthy controls. DDIT4 (2.79-fold upregulation) was then recognized as a candidate for the cis-regulated target of lncDDIT4 (4.32-fold upregulation). Isolation of naive CD4+ T cells revealed enhanced levels of lncDDIT4 and DDIT4 after stimulated with Th17-inducing cytokines, but not after Th1, Th2, or T regulatory cell induction. Overexpression of lncDDIT4 in naive CD4+ T cells inhibited IL-17 transcription through increased DDIT4 expression and decreased activation of the DDIT4/mTOR pathway. Consistently, silencing lncDDIT4 in naive CD4+ T cells enhanced Th17 differentiation through increased activation of the DDIT4/mTOR pathway. However, these results vanished when DDIT4 was silenced. This outcome suggests that lncDDIT4 regulates Th17 cell differentiation by directly targeting DDIT4.

Interaction of RNA-binding protein HuR and miR-466i regulates GM-CSF expression

Granulocyte-macrophage colony-stimulating factor (GM-CSF) produced by T helper 17 (Th17) cells plays an essential role in autoimmune diseases. Transcriptional regulation of Th17 cell differentiation has been extensively studied, but post-transcriptional regulation of Th17 cell differentiation has remained less well characterized. The RNA-binding protein HuR functions to promote the stability of target mRNAs via binding the AU-rich elements of the 3′ untranslated region (3′UTR) of numerous pro-inflammatory cytokines including IL-4, IL-13, IL-17 and TNF-α. However, whether HuR regulates GM-CSF expression in Th17 cells has not been fully investigated. Here we showed that HuR conditional knockout (KO) Th17 cells have decreased GM-CSF mRNA in comparison with wild-type (WT) Th17 cells, and that HuR binds directly to GM-CSF mRNA 3′UTR. Interestingly, HuR deficiency increased the levels of certain microRNA expression in Th17 cells; for example, miR-466i functioned to mediate GM-CSF and IL-17 mRNA decay, which was confirmed by in vitro luciferase assay. Furthermore, we found that HuR promoted Mxi1 expression to inhibit certain miRNA expression. Taken together, these findings indicate that interaction of HuR and miR-466i orchestrates GM-CSF expression in Th17 cells.

CD80 Regulates Th17 Cell Differentiation in Coxsackie Virus B3-Induced Acute Myocarditis.

The cluster of differentiation protein complex, CD80/CD86, regulates Th1/Th2 differentiation in autoimmune disease. In order to establish the effects of CD80/CD86 on Th17 cell differentiation in acute viral myocarditis (VMC), we infected C57BL/6 mice with Coxsackie virus B3 (CVB3) and examined the effects of the treatment with anti-CD80/CD86 monoclonal antibodies (mAbs) on Th17 cell differentiation in vivo. The effects of anti-CD80/CD86 mAbs on Th17 cell differentiation were further evaluated in vitro. The treatment with anti-CD80 mAb induced marked suppression of Th17 cell differentiation and ROR-γt mRNA expression, whereas anti-CD86 mAb alone had no effect, both in vivo and in vitro. Our finding that CD80 regulates Th17 differentiation supports the potential utility of anti-CD80 mAb as an effective new immunotherapeutic target in acute VMC.

Cyclic AMP-Responsive Element-Binding Protein (CREB) is Critical in Autoimmunity by Promoting Th17 but Inhibiting Treg Cell Differentiation

The molecular mechanisms that govern differential T cell development into pro-inflammatory Th17 vs. regulatory T (Treg) cells remain unclear. Here, we show that selective deletion of CREB in T cells or Th17 cells impaired Th17 cell differentiation in vitro and in vivo, and led to resistance to autoimmune diseases. Mechanistically, CREB, activated by CD3-PKC-ϴ signaling, plays a key role in regulating Th17 cell differentiation, at least in part through directly binding to the Il17-Il17f gene locus. Unexpectedly, although dispensable for FOXP3 expression and for the homeostasis and suppressive function of thymus-derived Treg cells, CREB negatively regulates the survival of TGF-β-induced Treg cells, and deletion of CREB resulted in increased FOXP3+ Treg cells in the intestine and protection in a colitis model. Thus, CREB is critical in autoimmune diseases by promoting Th17 cell and inhibiting de novo Treg cell generation.

PTEN drives Th17 cell differentiation by preventing IL-2 production.

T helper 17 (Th17) cells are a CD4+ T cell subset that produces IL-17A to mediate inflammation and autoimmunity. IL-2 inhibits Th17 cell differentiation. However, the mechanism by which IL-2 is suppressed during Th17 cell differentiation remains unclear. Here, we show that phosphatase and tensin homologue (PTEN) is a key factor that regulates Th17 cell differentiation by suppressing IL-2 production. Th17-specific Pten deletion (Ptenfl/flIl17acre ) impairs Th17 cell differentiation in vitro and ameliorated symptoms of experimental autoimmune encephalomyelitis (EAE), a model of Th17-mediated autoimmune disease. Mechanistically, Pten deficiency up-regulates IL-2 and phosphorylation of STAT5, but reduces STAT3 phosphorylation, thereby inhibiting Th17 cell differentiation. PTEN inhibitors block Th17 cell differentiation in vitro and in the EAE model. Thus, PTEN plays a key role in Th17 cell differentiation by blocking IL-2 expression.

Regulator of Calcineurin 3 Ameliorates Autoimmune Arthritis by Suppressing Th17 Cell Differentiation

Regulator of calcineurin 3 (RCAN3), an endogenous regulator of the calcineurin-nuclear factor of activated T cells (NFAT) signaling pathway, inhibits the phosphatase activity of calcineurin, the nuclear translocation of NFAT, and the NFAT downstream pathway. To investigate the effects of RCAN3 on T-cell regulatory function and the development and progression of inflammatory arthritis, we studied the effects of RCAN3 transfection on regulation of Th17 cell differentiation in a murine T-lymphoma cell line and primary splenic CD4+ T cells. Overexpression of RCAN3 suppressed Th17 cell differentiation through the down-regulation of RAR receptor orphan receptor γT mRNA and up-regulation of forkhead box P3 mRNA. In mice with collagen-induced arthritis, injection of an RCAN3-overexpression vector controlled arthritis development invivo. Injection ofRCAN3 reduced the formation of osteoclasts and expression of inflammatory cytokines invivo. Antioxidants stimulated the expression of RCAN3 invitro, and combination therapy with pcDNA-RCAN3 had a synergistic suppressive effect on the development of arthritis. These data suggest that RCAN3 may be an effective treatment for rheumatoid arthritis.

RGC-32 Promotes Th17 Cell Differentiation and Enhances Experimental Autoimmune Encephalomyelitis.

Th17 cells play a critical role in autoimmune diseases, including multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis. Response gene to complement (RGC)-32 is a cell cycle regulator and a downstream target of TGF-β that mediates its profibrotic activity. In this study, we report that RGC-32 is preferentially upregulated during Th17 cell differentiation. RGC-32-/- mice have normal Th1, Th2, and regulatory T cell differentiation but show defective Th17 differentiation in vitro. The impaired Th17 differentiation is associated with defects in IFN regulatory factor 4, B cell-activating transcription factor, retinoic acid-related orphan receptor γt, and SMAD2 activation. In vivo, RGC-32-/- mice display an attenuated experimental autoimmune encephalomyelitis phenotype accompanied by decreased CNS inflammation and reduced frequency of IL-17- and GM-CSF-producing CD4+ T cells. Collectively, our results identify RGC-32 as a novel regulator of Th17 cell differentiation in vitro and in vivo and suggest that RGC-32 is a potential therapeutic target in multiple sclerosis and other Th17-mediated autoimmune diseases.

Reciprocal regulation of Th17 and Treg cell differentiation by RhoA

Abstract Th17 cells are important for protective immunity as well as tissue inflammation and autoimmune disorders. Treg cells, including induced Treg (iTreg) and natural Treg (nTreg), play a critical role in immune tolerance. RhoA of the Rho small GTPase family is an intracellular signal transducer that cycles between an inactive GDP-bound form and an active GTP-bound form. We have previously reported that RhoA plays an important role in Th2 cell differentiation by regulating glycolysis. In this study, we further examined the role of RhoA in Th17 and Treg cell differentiation. Genetic deletion of RhoA in T cells or pharmacologic inhibition of RhoA by a RhoA-specific inhibitor Y16 led to reduced Th17 differentiation in vitro as evidenced by reduction of Th17 effector cytokines, transcriptional downregulation of RORγT and reduced phosphorylation of Stat3. Accordingly, RhoA deficiency ameliorated house dust mites (HDM)-induced allergic airway inflammation and dextran sodium sulphate (DSS)-induced colitis in vivo where Th17 cells plays an important role. Inhibition of ROCK, an immediate downstream effector of RhoA, recapitulated the effect of RhoA deficiency or inhibition on Th17 differentiation, suggesting that RhoA regulates Th17 cell differentiation through ROCK. On the other hand, ablation of RhoA had no effect on iTreg cell differentiation. However, inhibition of ROCK enhanced iTreg differentiation, suggesting that ROCK has RhoA-independent role in iTreg differentiation. In contrast to its in-effect on iTreg differentiation, RhoA deficiency increased nTreg differentiation. Thus, our data have provided new insights into Th17 and Treg differentiation and identified RhoA as a potential therapeutic target for tissue inflammation.

Suppression of Th17 cell differentiation by misshapen/NIK-related kinase MINK1.

T helper type 17 cells (Th17 cells) are major contributors to many autoimmune diseases. In this study, we demonstrate that the germinal center kinase family member MINK1 (misshapen/NIK-related kinase 1) negatively regulates Th17 cell differentiation. The suppressive effect of MINK1 on induction of Th17 cells is mediated by the inhibition of SMAD2 activation through direct phosphorylation of SMAD2 at the T324 residue. The importance of MINK1 to Th17 cell differentiation was strengthened in the animal model of experimental autoimmune encephalomyelitis (EAE). Moreover, we show that the reactive oxygen species (ROS) scavenger N-acetyl cysteine boosts Th17 cell differentiation in a MINK1-dependent manner and exacerbates the severity of EAE. Thus, we have not only established MINK1 as a critical regulator of Th17 cell differentiation, but also clarified that accumulation of ROS may limit the generation of Th17 cells. The contribution of MINK1 to ROS-regulated Th17 cell differentiation may suggest an important mechanism for the development of autoimmune diseases influenced by antioxidant dietary supplements.

Basophil-derived IL-6 regulates TH17 cell differentiation and CD4 T cell immunity

Basophils are rare, circulating granulocytes proposed to be involved in T helper (TH) type 2 immunity, mainly through secretion of interleukin (IL)-4. In addition to IL-4, basophils produce IL-6 and tumor necrosis factor (TNF)-α in response to immunoglobulin E (IgE) crosslinking. Differentiation of TH17 cells requires IL-6 and transforming growth factor (TGF)-β, but whether basophils play a significant role in TH17 induction is unknown. Here we show a role for basophils in TH17 cell development by using in vitro T cell differentiation and in vivo TH17-mediated inflammation models. Bone marrow derived-basophils (BMBs) and splenic basophils produce significant amounts of IL-6 as well as IL-4 following stimulation with IgE crosslink or cholera toxin (CT). In addition, through IL-6 secretion, BMBs cooperate with dendritic cells to promote TH17 cell differentiation. In the TH17 lung inflammation model, basophils are recruited to the inflamed lungs following CT challenge, and TH17 responses are significantly reduced in the absence of basophils or IL-6. Furthermore, reconstitution with wild-type, but not IL-6-deficient, basophils restored CT-mediated lung inflammation. Lastly, basophil-deficient mice showed reduced phenotypes of TH17-dependent experimental autoimmune encephalomyelitis. Therefore, our results indicate that basophils are an important inducer of TH17 cell differentiation, which is dependent on IL-6 secretion.

MBD2 Regulates Th17 Cell Differentiation and Experimental Severe Asthma by Affecting IRF4 Expression.

Th17 cells and IL-17 participate in airway neutrophil infiltration characteristics in the pathogenesis of severe asthma. Methyl-CpG binding domain protein 2 (MBD2) expression increased in CD4+ T cells in peripheral blood samples of asthma patients. However, little is known about that epigenetic regulation of MBD2 in both immunological pathogenesis of experimental severe asthma and CD4+ T cell differentiation. Here, we established a neutrophil-predominant severe asthma model, which was characterized by airway hyperresponsiveness (AHR), BALF neutrophil granulocyte (NEU) increase, higher NEU and IL-17 protein levels, and more Th17 cell differentiation. In the model, MBD2 and IRF4 protein expression increased in the lung and spleen cells. Under overexpression or silencing of the MBD2 and IRF4 gene, the differentiation of Th17 cells and IL-17 secretion showed positive changes. IRF4 protein expression showed a positive change with overexpression or silencing of the MBD2 gene, whereas there was no significant difference in the expression of MBD2 under overexpression or silencing of the IRF4 gene. These data provide novel insights into epigenetic regulation of severe asthma.