Epigenetic initiation of the TH17 differentiation program is promoted by Cxxc finger protein 1.
ABSTRACT: IL-6/STAT3 signaling is known to initiate the TH17 differentiation program, but the upstream regulatory mechanisms remain minimally explored. Here, we show that Cxxc finger protein 1 (Cxxc1) promoted the generation of TH17 cells as an epigenetic regulator and prevented their differentiation into Treg cells. Mice with a T cell-specific deletion of Cxxc1 were protected from experimental autoimmune encephalomyelitis and were more susceptible to Citrobacter rodentium infection. Cxxc1 deficiency decreased IL-6Rα expression and impeded IL-6/STAT3 signaling, whereas the overexpression of IL-6Rα could partially reverse the defects in Cxxc1-deficient TH17 cells in vitro and in vivo. Genome-wide occupancy analysis revealed that Cxxc1 bound to Il6rα gene loci by maintaining the appropriate H3K4me3 modification of its promoter. Therefore, these data highlight that Cxxc1 as a key regulator governs the balance between TH17 and Treg cells by controlling the expression of IL-6Rα, which affects IL-6/STAT3 signaling and has an impact on TH17-related autoimmune diseases.
Project description:IL-6/STAT3 signalling is known to initiate the Th17 differentiation programme, but the upstream regulatory mechanisms remain minimally explored. Here, we show that Cxxc finger protein 1 (Cxxc1) promoted the generation and stability of Th17 cells as an epigenetic regulator and prevented their differentiation into Treg cells. Mice with a T cell-specific deletion of Cxxc1 were protected from experimental autoimmune encephalomyelitis and were more susceptible to Citrobacter rodentium infection. Cxxc1-deficient T cells acquired a Treg cell-biased programme that dominantly suppressed Th17 cell generation via IL-6Rα production. Cxxc1 deficiency decreased IL-6Rα expression and impeded IL-6/STAT3 signalling, whereas the overexpression of IL-6Rα could reverse the defects seen in Cxxc1-deficient Th17 cells in vitro and in vivo. Genome-wide occupancy analysis revealed that Cxxc1 bound to Il6rα gene loci in the Th17 programme by maintaining the appropriate H3K4me3 modification of its promoter. Therefore, these data highlight that Cxxc1 as a key regulator governs the balance between Th17 and Treg cells by controlling the expression of IL-6Rα, which subsequently affects IL-6/STAT3 signalling and has a direct impact on Th17-related autoimmune diseases. Overall design: TH17 CHIP-SEQ
Project description:Human autoimmune diseases are characterized by systemic T cell dysfunction, resulting in chronically activated Th1 and Th17 cells that are inadequately suppressed by regulatory T cells (Tregs). IL-6, which is overexpressed in tissue and serum of patients with autoimmune diseases, inhibits human Treg function. We sought to determine the mechanism for the antitolerogenic properties of IL-6 by examining the signaling pathways downstream of IL-6R in primary human T cells. Inhibition of Stat3 signaling in MLCs containing IL-6 restores Treg-mediated suppression, demonstrating that IL-6-mediated loss of Treg suppression requires phosphorylation of Stat3. Cultures in which either effector T cells (Teffs) or Tregs were pretreated with Stat3 inhibitors indicate that phosphorylated (p)Stat3 is required in both T cell populations for IL-6-mediated reversal of Treg function. IL-21, which signals preferentially through pStat3, also reverses Treg suppression, in contrast to IL-27 and IFN-?, which signal preferentially through Stat1 and do not inhibit Treg function. Interestingly, both Teffs and Tregs respond to IL-6 stimulation through strong Stat3 phosphorylation with minimal MAPK/Erk activation and moderate Stat1 phosphorylation. Finally, Teffs stimulated strongly through the TCR are also resistant to suppression by Tregs and show concurrent Stat3 phosphorylation. In these cultures, inhibition of pStat3 restores functional suppression by Tregs. Taken together, our findings suggest that an early dominance of Stat3 signaling, prior to subsequent T cell activation, is required for the loss of functional Treg suppression and that kinase-specific inhibitors may hold therapeutic promise in the treatment of autoimmune and chronic inflammatory diseases.
Project description:Th17 cells promote inflammatory reactions, whereas regulatory T (Treg) cells inhibit them. Thus, the Th17/Treg cell balance is critically important in inflammatory diseases. However, the molecular mechanisms underlying this balance are unclear. Here, we demonstrate that casein kinase 2 (CK2) is a critical determinant of the Th17/Treg cell balance. Both the inhibition of CK2 with a specific pharmacological inhibitor, CX-4945, and its small hairpin RNA (shRNA)-mediated knockdown suppressed Th17 cell differentiation but reciprocally induced Treg cell differentiation in vitro. Moreover, CX-4945 ameliorated the symptoms of experimental autoimmune encephalomyelitis and reduced Th17 cell infiltration into the central nervous system. Mechanistically, CX-4945 inhibited the IL-6/STAT3 and Akt/mTOR signaling pathways. Thus, CK2 has a crucial role in regulating the Th17/Treg balance.
Project description:Effector CD4+ T cell subsets, whose differentiation is facilitated by distinct cytokine cues, amplify the corresponding type of inflammatory response. Regulatory T (Treg) cells integrate environmental cues to suppress particular types of inflammation. In this regard, STAT3, a transcription factor essential for T helper 17 (Th17) cell differentiation, is necessary for Treg cell-mediated control of Th17 cell responses. Here, we showed that anti-inflammatory interleukin-10 (IL-10), and not proinflammatory IL-6 and IL-23 cytokine signaling, endowed Treg cells with the ability to suppress pathogenic Th17 cell responses. Ablation of the IL-10 receptor in Treg cells resulted in selective dysregulation of Th17 cell responses and colitis similar to that observed in mice harboring STAT3-deficient Treg cells. Thus, Treg cells limit Th17 cell inflammation by serving as principal amplifiers of negative regulatory circuits operating in immune effector cells.
Project description:Regulatory T (Treg) and T helper 17 (Th17) cells were recently proposed to be reciprocally regulated during differentiation. To understand the underlying mechanisms, we utilized a Th17 reporter mouse with a red fluorescent protein (RFP) sequence inserted into the interleukin-17F (IL-17F) gene. Using IL-17F-RFP together with a Foxp3 reporter, we found that the development of Th17 and Foxp3(+) Treg cells was associated in immune responses. Although TGF-beta receptor I signaling was required for both Foxp3 and IL-17 induction, SMAD4 was only involved in Foxp3 upregulation. Foxp3 inhibited Th17 differentiation by antagonizing the function of the transcription factors RORgammat and ROR*. In contrast, IL-6 overcame this suppressive effect of Foxp3 and, together with IL-1, induced genetic reprogramming in Foxp3(+) Treg cells. STAT3 regulated Foxp3 downregulation, whereas STAT3, RORgamma, and ROR* were required for IL-17 expression in Treg cells. Our data demonstrate molecular antagonism and plasticity of Treg and Th17 cell programs.
Project description:Th17 cells are potent mediators in autoimmune diseases, and ROR?t is required for their development. Recent studies have shown that ROR?t+ Treg cells in the gut regulate intestinal inflammation by inhibiting effector T cell function. In the current study, we report that ROR?t+ Treg cells were also found in lymph nodes following immunization. Not only distinct from intestinal ROR?t+ Treg cells in their transcriptomes, peripheral ROR?t+ Treg cells were derived from Foxp3+ thymic Treg cells in an antigen-specific manner. Development of these ROR?t+ Treg cells, coined T regulatory 17 (Tr17) cells, depended on IL-6/Stat3 signaling. Tr17 cells showed suppressive activity against antigen-specific effector T cells in vitro. In addition, Tr17 cells efficiently inhibited myelin-specific Th17-cell-mediated CNS auto-inflammation in a passive EAE model. Collectively, our study demonstrates that Tr17 cells are effector Treg cells that potentially restrict autoimmunity.
Project description:PTEN is a tyrosine phosphatase with significant function in inhibiting STAT3 activation. Recently, inactivation of STAT3 has been demonstrated as a therapeutic candidate for autoimmune arthritis. The expression of PTEN controlled by p53 regulates autoimmune arthritis through modulating the balance between Th17 and Treg. We hypothesized that PTEN regulated by p53 might reduce CIA severity and inflammatory response via inhibiting STAT3 activation. Our results revealed that PTEN could ameliorate experimental autoimmune arthritis by reducing STAT3 activity and Th17 differentiation. Systemic infusion of PTEN overexpression downregulated CIA severity. In addition, PTEN overexpression decreased the activation of T cells and modulated reciprocal differentiation of Th17 and Treg cells. We observed that PTEN expression downregulated by p53 deficiency induced the activation of STAT3. Loss of p53 exacerbated autoimmune arthritis and dysregulated the population of Th17 and Treg. These data suggest that induction of STAT3-modulatory activity of PTEN may be a therapeutic target for rheumatoid arthritis therapy.
Project description:Th17 cells, a lymphocyte subpopulation that is characterized by the expression of the transcription factor "retinoic acid receptor-related orphan receptor gamma-t" (ROR?t), plays an important role in the pathogenesis of autoimmune disease. The current study was set up to discover novel and non-steroidal small-molecule inverse agonists of ROR?t and to determine their effects on autoimmune disease. Structure-based virtual screening (SBVS) was used to find compounds targeting ROR?t. Flow cytometry was used to detect the Th17 cell differentiation. Inverse agonists were intraperitoneally administered to mice undergoing experimental autoimmune uveitis (EAU), experimental autoimmune encephalomyelitis (EAE) or type 1 diabetes. The effects of the inverse agonists were evaluated by clinical or histopathological scoring. Among 1.3 million compounds screened, CQMU151 and CQMU152 were found to inhibit Th17 cell differentiation without affecting the differentiation of Th1 and Treg lineages (both P?=?0.001). These compounds also reduced the severity of EAU (P?=?0.01 and 0.013) and functional studies showed that they reduced the number of Th17 cell and the expression of IL-17(Th17), but not IFN-?(Th1) and TGF-?(Treg) in mouse retinas. Further studies showed that these compounds may reduce the expression of p-STAT3 by reducing the positive feedback loop of IL-17/IL-6/STAT3. These compounds also reduced the impaired blood-retinal barrier function by upregulating the expression of tight junction proteins. These compounds were also found to reduce the severity of EAE and type 1 diabetes. Our results showed that ROR?t inverse agonists may inhibit the development of autoimmune diseases and may provide new clues for the treatment of Th17-mediated immune diseases.
Project description:Disrupted balance in the lineages of CD4+ T cell subsets, including pro-inflammatory T helper (Th) cells and anti-inflammatory regulatory T cells (Treg), is a primary pathogenic factor for developing autoimmunity. We have found that this immunomodulatory effect of naringenin on effector T cells and T-cell mediated experimental autoimmune encephalomyelitis (EAE). We therefore explored the effects of naringenin on the development of different effector CD4+ T cells. Naïve CD4+ T cells were differentiated under respective Th1, Th2, Th17, and Treg polarizing conditions with naringenin. Percent populations of each differentiated CD4+ T cell subsets were determined and the corresponding regulating pathways were investigated as underlying mechanisms. Naringenin mainly inhibited CD4+ T cell proliferation and differentiation to Th1 and Th17, but did not affect Th2 cells. Impeded Th1 polarization was associated with inhibition of its specific regulator proteins T-bet, p-STAT1, and p-STAT4 by naringenin. Likewise, Th17 regulator proteins ROR?t, p-STAT3, and Ac-STAT3 were also inhibited by naringenin. In addition, naringenin promoted Treg polarization and also prevented IL-6-induced suppression of Treg development via down-regulation of p-Smad2/3 as well as inhibition of IL-6 signaling, and the latter was further supported by the in vivo results showing lower soluble IL-6R but higher soluble gp130 levels in plasma of naringenin-fed compared to the control EAE mice. Naringenin impacts CD4+ T cell differentiation in a manner that would explain its beneficial effect in preventing/mitigating T cell-mediated autoimmunity.
Project description:<h4>Aims</h4>Extensive evidence suggests inflammatory components participate in the pathogenic processes of acute coronary syndromes (ACS). In this study, we aimed to elucidate the role and mechanism underlying the imbalance of Th17 and Treg cell peripheral populations in the pathogenesis of ACS.<h4>Methods and results</h4>Using a flow cytometric analysis, we observed a significantly increased frequency of Th17 cells and a concurrently decreased CD4(+)CD25(+)Foxp3(+) Treg cells in patients with ACS. To elucidate the mechanism of Th17/Treg imbalance in ACS, 22 inflammatory cytokines were measured using multiplexed immunobead-based assays. Of six elevated cytokines in ACS patients, only IL-6 was positively correlated with a higher Th17 cell level (r?=?0.39, P<0.01). Relying on IL-6 stimulating and neutralizing studies, we demonstrated a direct role for IL-6 in sera from ACS patients with an increased frequency of Th17 cells. IL-6 induces the differentiation of Th17 cells from naïve CD4(+) T cells through STAT3 activation and ROR?t induction. However, we observed that high levels of TGF-?1 inhibited IL-6-dependent Th17 cell differentiation, indicating a complex interplay between the two cytokines in the control of Th17 and Treg cell populations.<h4>Conclusions</h4>Our results demonstrate the role of IL-6-STAT3 signaling in ACS through increased Th17 cell differentiation. These findings indicate that IL-6 neutralizing strategies could present novel therapeutic avenues in the treatment of ACS.