Stage-specific GATA3 induction promotes ILC2 development after lineage commitment.

Group 2 innate lymphoid cells (ILC2s) are a subset of innate lymphocytes that produce type 2 cytokines, including IL-4, IL-5, and IL-13. GATA3 is a critical transcription factor for ILC2 development at multiple stages. However, when and how GATA3 is induced to the levels required for ILC2 development remains unclear. Herein, we identify ILC2-specific GATA3-related tandem super-enhancers (G3SE) that induce high GATA3 in ILC2-committed precursors. G3SE-deficient mice exhibit ILC2 deficiency in the bone marrow, lung, liver, and small intestine with minimal impact on other ILC lineages or Th2 cells. Single-cell RNA-sequencing and subsequent flow cytometry analysis show that GATA3 induction mechanism, which is required for entering the ILC2 stage, is lost in IL-17RB+PD-1- late ILC2-committed precursor stage in G3SE-deficient mice. Cnot6l, part of the CCR4-NOT deadenylase complex, is a possible GATA3 target during ILC2 development. Our findings implicate a stage-specific regulatory mechanism for GATA3 expression during ILC2 development.

A distal enhancer of GATA3 regulates Th2 differentiation and allergic inflammation.

Asthma is a widespread airway disorder where GATA3-dependent Type-2 helper T (Th2) cells and group 2 innate lymphoid cells (ILC2s) play vital roles. Asthma-associated single nucleotide polymorphisms (SNPs) are enriched in a region located 926-970 kb downstream from GATA3 in the 10p14 (hG900). However, it is unknown how hG900 affects the pathogenesis of allergic airway inflammation. To investigate the roles of the asthma-associated GATA3 enhancer region in experimental allergic airway inflammation, we first examined the correlation between GATA3 expression and the activation of the hG900 region was analyzed by flow cytometry and ChIP-qPCR. We found that The activation of enhancers in the hG900 region was strongly correlated to the levels of GATA3 in human peripheral T cell subsets. We next generated mice lacking the mG900 region (mG900KO mice) were generated by the CRISPR-Cas9 system, and the development and function of helper T cells and ILCs in mG900KO mice were analyzed in steady-state conditions and allergic airway inflammation induced by papain or house dust mite (HDM). The deletion of the mG900 did not affect the development of lymphocytes in steady-state conditions or allergic airway inflammation induced by papain. However, mG900KO mice exhibited reduced allergic inflammation and Th2 differentiation in the HDM-induced allergic airway inflammation. The analysis of the chromatin conformation around Gata3 by circular chromosome conformation capture coupled to high-throughput sequencing (4C-seq) revealed that the mG900 region interacted with the transcription start site of Gata3 with an influencing chromatin conformation in Th2 cells. These findings indicate that the mG900 region plays a pivotal role in Th2 differentiation and thus enhances allergic airway inflammation.

Eosinophils Contribute to Oral Tolerance via Induction of RORγt-Positive Antigen-Presenting Cells and RORγt-Positive Regulatory T Cells.

Oral tolerance has been defined as the specific suppression of immune responses to an antigen by prior oral administration of the antigen. It has been thought to serve to suppress food allergy. Previous studies have shown that dendritic cells (DCs) and regulatory T cells (Tregs) are involved in the induction of oral tolerance. However, the detailed mechanisms of Treg induction in oral tolerance remain largely unknown. Eosinophils have been recognized as effector cells in allergic diseases, but in recent years, the diverse functions of tissue-resident eosinophils have been reported. Eosinophils in the intestine have been reported to induce Tregs by releasing TGF-ß, but the role of eosinophils in oral tolerance is still controversial. In this study, we analyzed the roles of eosinophils in oral tolerance using eosinophil-deficient ΔdblGATA mice (mice lacking a high-affinity GATA-binding site in the GATA1 promoter). ΔdblGATA mice showed impaired antigen-induced oral tolerance compared to wild-type mice. The induction of RORγt+ Tregs in mesenteric lymph nodes (MLNs) by oral tolerance induction was impaired in ΔdblGATA mice compared to wild-type mice. An increase in RORγt+ antigen-presenting cells (APCs), which are involved in RORγt+ Treg differentiation, in the intestine and MLNs was not seen in ΔdblGATA mice. Notably, the expansion of group 3 innate lymphoid cells (ILC3s), a subset of RORγt+ APCs, by oral tolerance induction was seen in wild-type mice but not ΔdblGATA mice. These results suggest that eosinophils are crucial in the induction of oral tolerance, possibly via the induction of RORγt+ APCs and RORγt+ Tregs.

IL-21 is required for the maintenance and pathogenesis of murine Vγ4+ IL-17-producing γδT cells.

Murine IL-17-producing γδT (γδT17) cells are divided into two subsets: natural γδT17 (nγδT17) cells, whose development is restricted to the fetal thymus, and inducible γδT17 cells, which require antigen exposure for their IL-17 production and are presumed to develop from Rorc + Il17a - CCR9 + immature γδT17 cells in the adult thymus and whose T cell receptor (TCR) is biased toward Vγ4. Although IL-23 is known to be involved in developing γδT17 cells, the roles of other cytokines, such as IL-21, which is involved in developing Th17 cells like IL-23, in the development, maintenance, and pathophysiology of γδT17 cells remain unknown. Here, we show that IL-21 is dispensable for the fetal thymic development of nγδT17 cells but is required for the peripheral maintenance of Vγ4+nγδT17 cells. Upon stimulation with γδTCR, IL-1 plus IL-21 induces the proliferation of Vγ4+nγδT17 cells via STAT3 as effectively as IL-1 plus IL-23. Using bone marrow chimeric mice, we demonstrated that immature γδT17 cells are produced de novo in the adult mice from donor adult bone marrow cells and that IL-21 is dispensable for their development. Instead, IL-21 is required to expand newly induced Vγ4+γδT17 cells in the periphery upon immunization. Finally, using adoptive transfer experiments of γδT17 cells, we found that IL-21 receptors on γδT17 cells are involved in maintaining Vγ4+γδT17 cells, subsequent infiltration of Th17 cells into the spinal cord, and exacerbation of experimental autoimmune encephalomyelitis. Collectively, IL-21 plays a vital role in the maintenance and pathogenesis of Vγ4+γδT17 cells.

CCR4 predicts the efficacy of abatacept in rheumatoid arthritis patients through the estimation of Th17 and Treg cell abundance.

OBJECTIVE: Predicting the efficacy of biological disease-modifying anti-rhematic drugs (bDMARDs) is challenging. In this study, we aimed to explore markers that predict the efficacy of abatacept in rheumatoid arthritis (RA) patients. METHODS: Thirty RA patients receiving abatacept were recruited, and peripheral blood mononuclear cells (PBMCs) from the participants were subjected to DNA microarray analysis. The expression of CCR4, which was selected by the result of DNA microarray, was determined by flow cytometry in 16 newly diagnosed treatment-naïve RA patients. CCR4 expression on each helper T cell subset was also measured. RESULTS: CCR4 was upregulated in the abatacept responder. The expression levels of CCR4 were significantly correlated with the improvement of clinical disease activity index (CDAI). CCR4 expression was predominantly observed in CD4+ T cells in PBMCs. The percentage of CCR4-expressing CD4+ T cells was significantly higher in RA patients than in healthy individuals. Interestingly, Th17 and Treg cells expressed high levels of CCR4 compared to non-Th17-related helper T cells. CONCLUSION: CCR4 is a Th17- and Treg-related gene, and the high CCR4 expression in peripheral blood samples may predict the efficacy of abatacept in RA.

TAp63, a methotrexate target in CD4+ T cells, suppresses Foxp3 expression and exacerbates autoimmune arthritis.

Methotrexate (MTX) is a standard, first-line therapy for rheumatoid arthritis (RA); however, its precise mechanisms of action other than antifolate activity are largely unknown. We performed DNA microarray analyses of CD4+ T cells in patients with RA before and after MTX treatment and found that TP63 was the most significantly downregulated gene after MTX treatment. TAp63, an isoform of TP63, was highly expressed in human IL-17-producing Th (Th17) cells and was suppressed by MTX in vitro. Murine TAp63 was expressed at high levels in Th cells and at lower levels in thymus-derived Treg cells. Importantly, TAp63 knockdown in murine Th17 cells ameliorated the adoptive transfer arthritis model. RNA-Seq analyses of human Th17 cells overexpressing TAp63 and those with TAp63 knockdown identified FOXP3 as a possible TAp63 target gene. TAp63 knockdown in CD4+ T cells cultured under Th17 conditions with low-dose IL-6 increased Foxp3 expression, suggesting that TAp63 balances Th17 cells and Treg cells. Mechanistically, TAp63 knockdown in murine induced Treg (iTreg) cells promoted hypomethylation of conserved noncoding sequence 2 (CNS2) of the Foxp3 gene and enhanced the suppressive function of iTreg cells. Reporter analyses revealed that TAp63 suppressed the activation of the Foxp3 CNS2 enhancer. Collectively, TAp63 suppresses Foxp3 expression and exacerbates autoimmune arthritis.

A role of Achaete-scute complex homolog 2 in T follicular regulatory cell development.

T follicular regulatory (Tfr) cells, a subset of CD4+ Foxp3+ regulatory T (Treg) cells, locate to the lymphoid follicle and germinal center (GC) and regulate antibody responses. Tfr cells express the functional molecules of follicular helper T (Tfh) cells, including CXCR5 and Bcl6. CD25- mature Tfr cells differentiate from CD25+ Treg cells through CD25+ immature Tfr cells. Others and we have shown that Achaete-scute complex homolog 2 (Ascl2) plays a role in Tfh cell development; however, the role of Ascl2 in the development of Tfr cells remains unclear. Here, we found that Ascl2 was highly and preferentially expressed in CD25+ Tfr cells and CD25- Tfr cells, and that the differentiation from CD25+ Tfr cells to CD25- Tfr cells was impaired by the absence of Ascl2. Furthermore, the forced Ascl2 expression in Treg cells downregulated CD25 expression and suppressed IL-2-induced phosphorylation of STAT5, which is known to suppress CD25- Tfr cell development. Finally, we found that the downregulation of CD25 by Ascl2 in Treg cells is independent of Bach2, which also regulates CD25 downregulation in CD25+ Tfr cells. These results suggest that Ascl2 plays a vital role in developing Tfr cells, possibly by downregulating CD25 expression in a Bach2-independent mechanism.

Epithelial cell-derived cytokine TSLP activates regulatory T cells by enhancing fatty acid uptake.

Epithelial cells control a variety of immune cells by secreting cytokines to maintain tissue homeostasis on mucosal surfaces. Regulatory T (Treg) cells are essential for immune homeostasis and for preventing tissue inflammation; however, the precise molecular mechanisms by which epithelial cell-derived cytokines function on Treg cells in the epithelial tissues are not well understood. Here, we show that peripheral Treg cells preferentially respond to thymic stromal lymphoprotein (TSLP). Although TSLP does not affect thymic Treg differentiation, TSLP receptor-deficient induced Treg cells derived from naïve CD4+ T cells are less activated in an adoptive transfer model of colitis. Mechanistically, TSLP activates induced Treg cells partially through mTORC1 activation and fatty acid uptake. Thus, TSLP modulates the activation status of induced Treg through the enhanced uptake of fatty acids to maintain homeostasis in the large intestine.

A20 (Tnfaip3) expressed in CD4+ T cells suppresses Th2 cell-mediated allergic airway inflammation in mice.

A20 (Tnfaip3), a ubiquitin-editing enzyme, inhibits NF-κB signaling pathways in response to pro-inflammatory cytokines. Previous studies have proved the anti-inflammatory roles of A20 in various cell types, including T cells, B cells, dendritic cells, and intestinal epithelial cells. Moreover, recent studies have shown that A20 expressed in lung epithelial cells is required for LPS-induced protection from asthma. In humans, a single-nucleotide polymorphism in TNFAIP3 is associated with asthma risk. However, the role of A20 expressed in T cells in asthmatic responses has not been elucidated. We addressed this point by generating mice lacking A20 expression in T cells (CD4-CreA20 fl/fl mice). We found that house dust mite (HDM)-induced allergic airway inflammation, mucus production, airway hyperresponsiveness, and Th2 cytokine production were significantly exacerbated in CD4-CreA20 fl/fl mice compared with those in control A20 fl/fl mice. In vitro differentiation of Th2 cells but not of Th1 cells or Th17 cells was enhanced in CD4+ T cells by the absence of A20. Consistently, enforced expression of A20 inhibited the differentiation of Th2 cells but not of Th1 cells or Th17 cells. Notably, the expression of GATA3 was significantly enhanced in A20-deficient CD4+ T cells, and the enhanced GATA3 expression was partly canceled by IL-2 neutralization. These results suggest that A20 functions as a stabilizing factor maintaining GATA3 levels during the induction of Th2 cells to prevent excessive Th2 cell differentiation.

Semaphorin 3G exacerbates joint inflammation through the accumulation and proliferation of macrophages in the synovium.

OBJECTIVES: Methotrexate (MTX) is an anchor drug for the treatment of rheumatoid arthritis (RA). However, the precise mechanisms by which MTX stalls RA progression and alleviates the ensuing disease effects remain unknown. The aim of the present study was to identify novel therapeutic target molecules, the expression patterns of which are affected by MTX in patients with RA. METHODS: CD4+ T cells from 28 treatment-naïve patients with RA before and 3 months after the initiation of MTX treatment were subjected to DNA microarray analyses. The expression levels of semaphorin 3G, a differentially expressed gene, and its receptor, neuropilin-2, were evaluated in the RA synovium and collagen-induced arthritis synovium. Collagen-induced arthritis and collagen antibody-induced arthritis were induced in semaphorin3G-deficient mice and control mice, and the clinical score, histological score, and serum cytokines were assessed. The migration and proliferation of semaphorin 3G-stimulated bone marrow-derived macrophages were analyzed in vitro. The effect of local semaphorin 3G administration on the clinical score and number of infiltrating macrophages during collagen antibody-induced arthritis was evaluated. RESULTS: Semaphorin 3G expression in CD4+ T cells was downregulated by MTX treatment in RA patients. It was determined that semaphorin 3G is expressed in RA but not in the osteoarthritis synovium; its receptor neuropilin-2 is primarily expressed on activated macrophages. Semaphorin3G deficiency ameliorated collagen-induced arthritis and collagen antibody-induced arthritis. Semaphorin 3G stimulation enhanced the migration and proliferation of bone marrow-derived macrophages. Local administration of semaphorin 3G deteriorated collagen antibody-induced arthritis and increased the number of infiltrating macrophages. CONCLUSIONS: Upregulation of semaphorin 3G in the RA synovium is a novel mechanism that exacerbates joint inflammation, leading to further deterioration, through macrophage accumulation.

NF-κB1 Contributes to Imiquimod-Induced Psoriasis-Like Skin Inflammation by Inducing Vγ4+Vδ4+γδT17 Cells.

Recent studies have identified NF-κB1 as a new disease susceptibility gene for psoriasis. Although accumulating evidence has shown the importance of NF-κB signaling in various cell types in the pathogenesis of psoriasis, it remains unclear how NF-κB1 contributes to the pathogenesis of psoriasis. In this study, we examined psoriasis-like skin diseases induced by topical administration of imiquimod in Nf-κb1‒deficient (Nf-κb1-/-) mice and littermate wild-type (WT) mice. Compared with WT mice, Nf-κb1-/- mice exhibited attenuated skin inflammation. The numbers of Vγ4+Vδ4+γδT17 cells, which cause skin inflammation in this model, were significantly reduced in the skin and draining lymph nodes in imiquimod-treated Nf-κb1-/- mice. Nf-κb1 is preferentially phosphorylated in Vγ4+Vδ4+γδT17 cells in WT mice. In vitro proliferation of Vγ4+Vδ4+γδT17 cells but not conventional CD4+ T cells was significantly impaired in Nf-κb1-/- mice compared with that in WT mice. RNA-sequencing analyses revealed that the expression of E2 factor target genes was decreased in Vγ4+Vδ4+γδT cells by the absence of NF-κB1. Consistently, the cell cycle progression of Vγ4+Vδ4+γδT cells was reduced in Nf-κb1-/- mice compared with that in WT mice. These results suggest that Nf-κb1 plays a crucial role in the pathogenesis of imiquimod-induced psoriasis-like skin inflammation by promoting the proliferation of Vγ4+Vδ4+γδT17 cells.

Inhibition of Interleukin-21 prolongs the survival through the promotion of wound healing after myocardial infarction.

Ly6Clow macrophages promote scar formation and prevent early infarct expansion after myocardial infarction (MI). Although CD4+ T cells influence the regulation of Ly6Clow macrophages after MI, the mechanism remains largely unknown. Based on the hypothesis that some molecule(s) secreted by CD4+ T cells act on Ly6Clow macrophages, we searched for candidate molecules by focusing on cytokine receptors expressed on Ly6Clow macrophages. Comparing the transcriptome between Ly6Chigh macrophages and Ly6Clow macrophages harvested from the infarcted heart, we found that Ly6Clow macrophages highly expressed the receptor for interleukin (IL)-21, a pleiotropic cytokine which is produced by several types of CD4+ T cells, compared with Ly6Chigh macrophages. Indeed, CD4+ T cells harvested from the infarcted heart produce IL-21 upon stimulation. Importantly, the survival rate and cardiac function after MI were significantly improved in IL-21-deficient (il21-/-) mice compared with those in wild-type (WT) mice. Transcriptome analysis of infarcted heart tissue from WT mice and il21-/- mice at 5 days after MI demonstrated that inflammation is persistent in WT mice compared with il21-/- mice. Consistent with the transcriptome analysis, the number of neutrophils and matrix metalloproteinase (MMP)-9 expression were significantly decreased, whereas the number of Ly6Clow macrophages and MMP-12 expression were significantly increased in il21-/- mice. In addition, collagen deposition and the number of myofibroblasts in the infarcted area were significantly increased in il21-/- mice. Consistently, IL-21 enhanced the apoptosis of Ly6Clow macrophages. Finally, administration of neutralizing IL-21 receptor Fc protein increased the number of Ly6Clow macrophages in the infarcted heart and improved the survival and cardiac function after MI. Thus, IL-21 decreases the survival after MI, possibly through the delay of wound healing by inducing the apoptosis of Ly6Clow macrophages.

Suppressor of cytokine signalling 3 (SOCS3) expressed in podocytes attenuates glomerulonephritis and suppresses autoantibody production in an imiquimod-induced lupus model.

OBJECTIVE: Recently, podocytes have been recognised not only as a physical barrier to prevent urinary protein loss but also as producers of proinflammatory cytokines. However, the roles of podocytes in the pathogenesis of lupus nephritis (LN) remain largely unknown. This study aims to determine the roles of suppressor of cytokine signalling (SOCS) family members expressed in glomeruli in the regulation of LN. METHODS: We investigated the expression of SOCS family members in glomeruli in murine lupus model induced by repeated epicutaneous administration of the TLR7/8 agonist imiquimod. We also investigated the roles of SOCS3 expressed in podocytes in the imiquimod-induced glomerulonephritis and systemic autoimmunity by using podocyte-specific SOCS3-deficient mice (podocin-Cre x SOCS3fl/fl mice (SOCS3-cKO mice)). Finally, we investigated the expression of proinflammatory cytokines and chemokines in SOCS3-deficient podocyte cell lines. RESULTS: qPCR analysis revealed that among SOCS family members, SOCS3 was preferentially induced in glomeruli on epicutaneous administration of imiquimod and that interleukin 6 (IL-6) induced SOCS3 expression in podocyte cell lines. SOCS3-cKO mice exhibited severe glomerulonephritis, high levels of serum creatinine and urine albumin and decreased survival rate compared with control SOCS3-WT mice. Levels of anti-double-strand DNA antibody, SOCS (GC) formation and the numbers of follicular helper T (Tfh) cells and GC B cells in the spleen were higher in SOCS3-cKO mice than those in SOCS3-WT mice. Serum IL-6 levels and expression of IL-6 mRNA in glomeruli were also elevated in SOCS3-cKO mice. IL-6-induced IL-6 expression was enhanced in SOCS3-deficient podocyte cell lines compared with that in SOCS3-sufficient podocyte cell lines. CONCLUSION: SOCS3 expressed in podocytes plays protective roles for the development of glomerulonephritis and inhibits autoantibody production in the imiquimod-induced lupus model presumably by suppressing IL-6 production of podocytes.

Associations of ultrasound-based inflammation patterns with peripheral innate lymphoid cell populations, serum cytokines/chemokines, and treatment response to methotrexate in rheumatoid arthritis and spondyloarthritis.

OBJECTIVES: We aimed to explore the associations of musculoskeletal inflammation patterns with peripheral blood innate lymphoid cell (ILC) populations, serum cytokines/chemokines, and treatment response to methotrexate in patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA). METHODS: We enrolled 100 patients with either RA or SpA and performed ultrasound to evaluate power Doppler signals for synovitis (52 joint regions), tenosynovitis (20 tendons), and enthesitis (44 sites). We performed clustering analysis using unsupervised random forest based on the multi-axis ultrasound information and classified the patients into groups. We identified and counted ILC1-3 populations in the peripheral blood by flow cytometry and also measured the serum levels of 20 cytokines/chemokines. We also determined ACR20 response at 3 months in 38 patients who began treatment with methotrexate after study assessment. RESULTS: Synovitis was more prevalent and severe in RA than in SpA, whereas tenosynovitis and enthesitis were comparable between RA and SpA. Patients were classified into two groups which represented synovitis-dominant and synovitis-nondominant inflammation patterns. While peripheral ILC counts were not significantly different between RA and SpA, they were significantly higher in the synovitis-nondominant group than in the synovitis-dominant group (ILC1-3: p = 0.0007, p = 0.0061, and p = 0.0002, respectively). On the other hand, clustering of patients based on serum cytokines/chemokines did not clearly correspond either to clinical diagnoses or to synovitis-dominant/nondominant patterns. The synovitis-dominant pattern was the most significant factor that predicted clinical response to methotrexate (p = 0.0065). CONCLUSIONS: Musculoskeletal inflammation patterns determined by ultrasound are associated with peripheral ILC counts and could predict treatment response to methotrexate.

Sox12 enhances Fbw7-mediated ubiquitination and degradation of GATA3 in Th2 cells.

Allergic asthma that is caused by inhalation of house dust mites (HDMs) is mainly mediated by Th2 cells. Recently, the roles of Sox (SRY-related high-mobility-group (HMG)-box) family members in various immune responses have been investigated. However, the roles of Sox12, a member of the SoxC group, in Th2 cell differentiation and allergic airway inflammation, remain unknown. We showed that Sox12 mRNA was significantly increased during Th2 cell differentiation. In vivo, HDM-induced eosinophil infiltration into the lung and Th2 cell differentiation were exacerbated in Sox12-/- mice compared with those in control Sox12+/- mice. In vitro, Sox12-/- CD4+ T cells that were cultured under Th2 conditions had increased production of Th2 cytokines and GATA3 protein compared with those of control Sox12+/- CD4+ T cells. Importantly, forced expression of Sox12 decreased the protein levels of GATA3 in CD4+ T cells under Th2 conditions without affecting mRNA expression. Furthermore, Sox12 induced degradation of GATA3 through the proteasome pathway in CD4+ T cells. Consistently, Sox12 enhanced ubiquitination of GATA3, which was mediated by the E3 ligase Fbw7. Finally, we found that Fbw7 knockdown partly abrogated Sox12-mediated GATA3 suppression in CD4+ T cells. Taken together, these results suggest that Sox12 suppresses Th2 cell differentiation by accelerating Fbw7-mediated GATA3 degradation, and attenuates HDM-induced allergic inflammation.

T-bet and STAT6 Coordinately Suppress the Development of IL-9-Mediated Atopic Dermatitis-Like Skin Inflammation in Mice.

T-bet and signal transducer and activator of transcription (STAT) 6 are critical factors for helper T-cell differentiation in humans and mice. Additionally, polymorphisms in TBX21 (T-bet) and STAT6 are associated with the susceptibility of allergic diseases. However, precise mechanisms of the reciprocal regulation between T-bet and STAT6 in allergy remain unclear. To determine the reciprocal regulation in vivo, we investigated the phenotype of T-bet/STAT6 double-deficient (T-bet-/- STAT6-/-) mice. Unexpectedly, T-bet-/- STAT6-/- mice but not T-bet-/- mice or STAT6-/- mice spontaneously developed severe dermatitis. Not only eosinophils and mast cells but also CD4+ T cells infiltrated into the skin of T-bet-/- STAT6-/- mice. Adoptive transfer of CD4+ T cells of T-bet-/- STAT6-/- mice into severe combined immunodeficient mice induced the accumulation of eosinophils and mast cells in the skin, whereas depletion of CD4+ T cells ameliorated the dermatitis in T-bet-/- STAT6-/- mice. Comprehensive transcriptome analyses revealed that IL-9 expression was enhanced in T-bet-/- STAT6-/- CD4+ T cells. Indeed, IL-9 neutralization ameliorated the dermatitis in T-bet-/- STAT6-/- mice. T-bet-/- STAT6-/- CD4+ T cells expressed functional thymic stromal lymphopoietin receptors and produced large amounts of IL-9 on thymic stromal lymphopoietin stimulation. These results indicate that T-bet and STAT6 coordinately suppress atopic dermatitis-like skin inflammation, possibly by inhibiting thymic stromal lymphopoietin-dependent IL-9 production in CD4+ T cells.

RNA-Binding Protein ZFP36L2 Downregulates Helios Expression and Suppresses the Function of Regulatory T Cells.

The zinc finger protein 36-like 2, ZFP36L2, is a member of a small family of RNA-binding proteins composed by ZFP36 (also known as tristetraprolin, TTP), ZFP36L1 and ZFP36L2 in humans, with corresponding murine orthologs. These proteins bind to adenine uridine-rich element (ARE) in the 3'untranslated region of target messenger RNA and stimulate target degradation. ZFP36 functions as an anti-inflammatory modulator in murine models of inflammatory diseases by down-regulating the production of inflammatory cytokines such as tumor necrosis factor-α. However, how ZFP36L1 and ZFP36L2 alter the function of CD4+ T cells is not completely understood. We addressed this issue by searching for the target genes of ZFP36L2 by comprehensive transcriptome analysis. We observed that ZFP36L2 is highly expressed in naïve CD4+ T cells; however, when CD4+ T cells are stimulated through their T cell receptors, ZFP36L2 expression is rapidly reduced in both humans and mice. Among CD4+ T cell populations, the expression levels of ZFP36L2 in regulatory T cells (Tregs) were significantly lower than those in naïve or effector CD4+ T cells. RNA-sequence analysis revealed that the forced expression of ZFP36L2 decreased Ikzf2 (encoding Helios) expression in Foxp3+ Tregs and inhibited the ability of induced Tregs (iTregs). ZFP36L2 directly bound to and destabilized the 3'untranslated region of Ikzf2 mRNA, which contains AU-rich elements. These results indicate that ZFP36L2 reduces the expression of Ikzf2 and suppresses iTreg function, raising the interesting possibility that the inhibition of ZFP36L2 in iTregs could be a therapeutic strategy for autoimmune diseases.

Experience of musculoskeletal ultrasound scanning improves physicians' physical examination skills in assessment of synovitis.

OBJECTIVE: Musculoskeletal ultrasound (US) is more sensitive than physical examination in detecting synovitis and helps physicians to understand its pathophysiology. In this study, we aimed to determine if the experience in musculoskeletal US scanning is independently associated with improved physical examination skills to detect synovitis. METHOD: Seventy patients with rheumatoid arthritis and twenty-three physicians were enrolled. Patients were first assessed by multiple physicians with a range of clinical/sonographic experience for the swelling of the wrist, metacarpophalangeal and proximal interphalangeal (PIP) joints and next underwent US assessment performed by another physician experienced in musculoskeletal US. We then calculated the positive/negative predictive values (PPV/NPV) of joint swelling to identify US-detected synovial hypertrophy. Finally, the factors independently associated with the accuracy of clinical assessment were identified by using multivariate analyses. RESULTS: One thousand five hundred forty joints were assessed 6116 times in total for swelling. Overall, PPV and NPV of joint swelling were 51.7% and 88.3%, respectively. Multivariate analyses identified wrist joint, tenderness, male and greater patients' age as the factors significantly associated with higher PPV. In addition, there was a trend that longer experience in rheumatology clinical practice was associated with higher PPV (p = 0.058). On the other hand, longer experience in musculoskeletal US, PIP joint and positive rheumatoid factor were identified as the significant factors for higher NPV, while wrist joint, tenderness, presence of osteophyte and obesity as those for lower NPV. CONCLUSION: Our data suggest that the experience in musculoskeletal US improves physical examination skills particularly to avoid overestimation.Key Points• Physicians with longer US experience are less likely to overestimate synovitis by physical examination.• Musculoskeletal US is a useful tool for rheumatologists to improve their physical examination skill.• Presence of osteophytes, joint tenderness and obesity influence the accuracy of physical examination of joints.