Project description:Extensive cellular heterogeneity exists within specific immune-cell subtypes classified as a single lineage, but its molecular underpinnings are rarely characterized at a genomic scale. Here, we use single-cell RNA-seq to investigate the molecular mechanisms governing heterogeneity and pathogenicity of Th17 cells isolated from the central nervous system (CNS) and lymph nodes (LN) at the peak of autoimmune encephalomyelitis (EAE) or polarized in vitro under either pathogenic or non-pathogenic differentiation conditions. Computational analysis reveals a spectrum of cellular states in vivo, including a self-renewal state, Th1-like effector/memory states and a dysfunctional/senescent state. Relating these states to in vitro differentiated Th17 cells, unveils genes governing pathogenicity and disease susceptibility. Using knockout mice, we validate four novel genes: Gpr65, Plzp, Toso and Cd5l (in a companion paper). Cellular heterogeneity thus informs Th17 function in autoimmunity, and can identify targets for selective suppression of pathogenic Th17 cells while sparing non-pathogenic tissue-protective ones. Population transcriptional profiling of KO or WT cells,, differentiated in vitro for 48-96h towards Th17 cells
Project description:Peptidyl arginine deiminase 4 (PAD4) is an enzyme that is involved in protein citrullination, and is a target for anti-citrullinated peptide antibodies (ACPAs) in rheumatoid arthritis (RA). Genetic polymorphisms in the PADI4 gene encoding PAD4 are associated with RA susceptibility. We herein analyzed the roles of PADI4 in inflammatory arthritis using a glucose-6-phosphate isomerase (GPI)-induced arthritis (GIA) model in Padi4 knockout (KO) mice. Arthritis severity, serum anti-GPI antibody titers, and IL-6 concentrations were significantly reduced in Padi4 KO mice. The frequency of Th17 cells was decreased in GPI-immunized Padi4 KO mice, whereas WT and Padi4-deficient naïve CD4(+) T cells displayed the same efficiencies for Th17 cell differentiation in vitro. In addition, the numbers of myeloid lineage cells were reduced with the increased expression of pro-apoptotic genes in GPI-immunized Padi4 KO mice. Furthermore, the survival of Padi4-deficient neutrophils was impaired in vitro. Our results suggest that PADI4 exacerbates arthritis with diverse immunological modifications.
Project description:The etiology of sarcoidosis is unknown. In this study, Propionibacterium acnes (PA) was used to induce sarcoidosis-like granulomatous inflammation in a mouse model. Wild-Type (WT) C57BL/6 mice were divided into three groups: (1) WT-PA group; (2) WT-PA + Incomplete Freund's Adjuvant (IFA) group; and (3) WT-PBS group. Loose granuloma formation was observed in the lungs on day 56 in the WT-PA and WT-PA + IFA groups. The proportions of peripheral Th17 cells in the WT-PA (p = 0.0004) and WT-PA + IFA groups (p = 0.0005) were significantly higher than that in the WT-PBS group. The proportions of peripheral Treg cells in the WT-PA (p < 0.0001) and WT-PA + IFA groups (p < 0.0001) were lower than that in the WT-PBS group. Then, to explore the mechanism of IL-17, Wild-Type (WT) C57BL/6 mice were divided into three groups: (1) WT-PBS group (2) WT-PA group; (3) WT-PA + mouse IL-17A neutralizing antibody (IL-17Ab) group. IL-17A gene knockout mice (KO) were divided into two groups: (1) KO -PA group; (2) KO-PBS group. The KO-PA and WT-PA + IL-17Ab groups showed reduced inflammation and no loose granuloma formation on day 56. As compared to the WT-PA group, the ratio of peripheral Th17 in the KO-PA (p < 0.0001) and WT-PA + IL-17Ab groups (p < 0.0001) decreased, while the ratio of peripheral Treg in the KO-PA (p < 0.0001) and WT-PA + IL-17Ab (p = 0.0069) groups increased on day 56. Hence, PA can be used to establish a mouse model of sarcoidosis-like granuloma. IL-17A plays an important role in experimental sarcoidosis-like granuloma formation.
Project description:The type III histone deacetylase silent information regulator 1 (SIRT1) is an enzyme that is critical for the modulation of immune and inflammatory responses. However, the data on its role in rheumatoid arthritis (RA) are limited and controversial. To better understand how SIRT1 regulates adaptive immune responses in RA, we evaluated collagen-induced arthritis (CIA) in myeloid cell-specific SIRT1 knockout (mSIRT1 KO) and wild-type (WT) mice. Arthritis severity was gauged on the basis of clinical, radiographic and pathologic scores. Compared with their WT counterparts, the mSIRT1 KO mice exhibited less severe arthritis, which was less destructive to the joints. The expression levels of inflammatory cytokines, matrix metalloproteinases and ROR-?T were also reduced in the mSIRT1 KO mice compared with the WT mice and were paralleled by reductions in the numbers of Th1 and Th17 cells and CD80- or CD86-positive dendritic cells (DCs). In addition, impaired DC maturation and decreases in the Th1/Th17 immune response were observed in the mSIRT1 KO mice. T-cell proliferation was also investigated in co-cultures with antigen-pulsed DCs. In the co-cultures, the DCs from the mSIRT1 KO mice showed decreases in T-cell proliferation and the Th1/Th17 immune response. In this study, myeloid cell-specific deletion of SIRT1 appeared to suppress CIA by modulating DC maturation. Thus, a careful investigation of DC-specific SIRT1 downregulation is needed to gauge the therapeutic utility of agents targeting SIRT1 in RA.
Project description:OBJECTIVE: Th17 has been shown to have a pivotal role in the development of arthritis. However, the role of IL-17 in the T cell-independent effector phase has not fully been examined. We investigated whether IL-17 is involved in the effector phase of arthritis by using K/BxN serum-induced arthritis model. METHODS: K/BxN serum was transferred into IL-17 knockout (KO) mice, SCID mice and their control mice, and arthritis was evaluated over time. In order to clarify the source of IL-17 in the effector phase, neutrophils or CD4+ T cells collected from IL-17 KO or control mice were injected into IL-17 KO recipient mice together with K/BxN serum. To examine if neutrophils secrete IL-17 upon stimulation, neutrophils were stimulated with immune complex in?vitro and IL-17 in the supernatant was measured by ELISA. RESULTS: K/BxN serum-induced arthritis was much less severe in IL-17 KO mice than in WT mice. Since K/BxN serum-transferred SCID mice developed severe arthritis with high serum IL-17 concentration, we speculated neutrophils are the responsible player as an IL-17 source. When wild type (WT) but not IL-17 KO neutrophils were co-injected with K/BxN serum into IL-17 KO mice, arthritis was exacerbated, whereas co-injection of WT CD4+ T cells had no effect. In vitro, stimulation of neutrophils with immune complex caused IL-17 secretion. CONCLUSIONS: Neutrophils are essential as a source of IL-17 in the effector phase of arthritis. The trigger of secreting IL-17 from neutrophils may be immune complex.
Project description: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-?. 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.
Project description:<h4>Background</h4>Granulomatous and fibrosing inflammation in response to parasite eggs is the main pathology that occurs during infection with Schistosoma spp. CD4+ T cells play critical roles in both host immune responses against parasitic infection and immunopathology in schistosomiasis,and coordinate many types of immune cells that contribute to fibrosis. ICOSL plays an important role in controlling specific aspects of T cell activation, differentiation, and function. Previous work has suggested that ICOS is essential for Th17 cell development. However, the immunopathogenesis of this pathway in schistosomiasis fibrosisis still unclear.<h4>Methodology/principal findings</h4>Using models of schistosomiasis in ICOSL KO and the C57BL/6 WT mice, we studied the role of the ICOSL/ICOS interaction in the mediation of the Th17 response in host granulomatous inflammation, particularly in liver fibrosis during S. japonicum infection, and investigated the immune responses and pathology of ICOSL KO mice in these models. The results showed that ICOSL KO mice exhibited improved survival, reduced liver granulomatous inflammation around parasite eggs, markedly inhibited hepatic fibrosis development, lower levels of Th17-related cytokines (IL-17/IL-21), Th2-related cytokines (IL-4/IL-6/IL-10), a pro-fibrotic cytokine (IL-13), and TGF-?1, but higher level of Th1-related cytokine (IFN-?) compared to wild-type (WT) mice. The reduced progression of fibrogenesis was correlated with the down-regulation of Th17 and Th2 and the elimination of ICOSL/ICOS interactions.<h4>Conclusions/significance</h4>Our findings suggest that IL-17-producing cells contribute to the hepatic granulomatous inflammation and subsequent fibrosis. Importantly, there was a clearly positive correlation between the presence of IL-17-producing cells and ICOS expression in ICOSL KO mice, and additional results indicated that Th17 was involved in the pathological tissue remodeling in liver fibrosis induced by schistosomiasis.
Project description:Patients deficient in the cytoskeletal regulator Wiskott-Aldrich syndrome protein (WASp) are predisposed to varied autoimmunity, suggesting it has an important controlling role in participating cells. IL-10-producing regulatory B (Breg) cells are emerging as important mediators of immunosuppressive activity. In experimental, antigen-induced arthritis WASp-deficient (WASp knockout [WAS KO]) mice developed exacerbated disease associated with decreased Breg cells and regulatory T (Treg) cells, but increased Th17 cells in knee-draining LNs. Arthritic WAS KO mice showed increased serum levels of B-cell-activating factor, while their B cells were unresponsive in terms of B-cell-activating factor induced survival and IL-10 production. Adoptive transfer of WT Breg cells ameliorated arthritis in WAS KO recipients and restored a normal balance of Treg and Th17 cells. Mice with B-cell-restricted WASp deficiency, however, did not develop exacerbated arthritis, despite exhibiting reduced Breg- and Treg-cell numbers during active disease, and Th17 cells were not increased over equivalent WT levels. These findings support a contributory role for defective Breg cells in the development of WAS-related autoimmunity, but demonstrate that functional competence in other regulatory populations can be compensatory. A properly regulated cytoskeleton is therefore important for normal Breg-cell activity and complementation of defects in this lineage is likely to have important therapeutic benefits.
Project description:Women have increased prevalence of Th17-mediated autoimmune diseases, including lupus and multiple sclerosis, and severe asthma. While estradiol and progesterone increased IL-17A production in Th17 cells by inhibiting Let7f miRNA expression and increasing IL-23 receptor (IL-23R) expression, it remained unclear how estrogen signaling through the canonical nuclear receptors, estrogen receptor ? (ER?) and/or ER?, regulated this pathway. We hypothesized that estrogen signaling through ER? increased IL-23R expression and IL-17A production from Th17 cells. To test this hypothesis, naïve T cells from WT female, WT male, Esr1 -/- and Esr2 -/- female mice were differentiated into Th17 cells. IL-17A production and IL-23R expression were significantly increased in Th17 cells from WT female mice compared to Th17 cells from WT male mice. Deletion of ER? (Esr1 -/-), but not ER? (Esr2 -/-), significantly decreased IL-17A production and IL-23R expression in Th17 cells by limiting IL-23R expression in a Let-7f dependent manner. ER? deficiency also decreased Th17 cell proliferation as well as decreased T cell metabolism as measured by ATP-linked oxygen consumption rate and proton leakage. Further, we found that Cox20 expression, a protein involved in mitochondrial respiration through assembly of cytochrome c oxidase in the electron transport chain, was increased in Th17 cells from WT female mice compared to Th17 cells from WT male and Esr1 -/- female mice. Inhibition of Cox20 decreased IL-17 production in Th17 cells from WT female mice. Combined these studies showed that ER? signaling increased IL-17A production in Th17 cells by upregulating IL-23R expression and promoting mitochondrial respiration and proliferation.