Project description:RORgt is known to instruct the differentiation of Th17 cells that mediate the pathogenesis of autoimmune diseases. However, it remains unknown whether RORgt plays a distinct role in the differentiation and effector function of Th17 cells. Here we show that mutation of RORgt lysine 256, a ubiquitination site, to arginine (K256R) separates the RORgt role in these two functions. Preventing ubiquitination at K256 via arginine substitution does not affect RORgt-dependent thymocyte development and Th17 differentiation in vitro and in vivo, however, greatly impaired the pathogenesis of Th17 cell-mediated experimental autoimmune encephalomyelitis (EAE). Mechanistically, K256R mutation impairs RORgt to bind to and activate Runx1 expression critical for Th17-mediated EAE. Thus, RORgt regulates the effector function of Th17 cells in addition to Th17 differentiation. This work informs the development of RORgt-based therapies that specifically target the effector function of Th17 cells responsible for autoimmunity.
Project description:RORgt is known to instruct the differentiation of Th17 cells that mediate the pathogenesis of autoimmune diseases. However, it remains unknown whether RORgt plays a distinct role in the differentiation and effector function of Th17 cells. Here we show that mutation of RORgt lysine 256, a ubiquitination site, to arginine (K256R) separates the RORgt role in these two functions. Preventing ubiquitination at K256 via arginine substitution does not affect RORgt-dependent thymocyte development and Th17 differentiation in vitro and in vivo, however, greatly impaired the pathogenesis of Th17 cell-mediated experimental autoimmune encephalomyelitis (EAE). Mechanistically, K256R mutation impairs RORgt to bind to and activate Runx1 expression critical for Th17-mediated EAE. Thus, RORgt regulates the effector function of Th17 cells in addition to Th17 differentiation. This work informs the development of RORgt-based therapies that specifically target the effector function of Th17 cells responsible for autoimmunity.
Project description:In this study, we show that in addition to regulating DP thymocytes survival, RORgT also controls genes that regulate thymocyte migration, proliferation, and T cell receptor (TCR) selection. Strikingly, pharmacological inhibition of RORg skews TCR gene rearrangement, limits T cell repertoire diversity, and inhibits development of autoimmune encephalomyelitis. Thus, targeting RORgT not only inhibits Th17 cell development and function but also fundamentally alters thymic-emigrant recognition of self and foreign antigens.
Project description:Th17 cells are a helper cell subset of pro-inflammatory T cells, which have diverse functions ranging from neutrophilic-inflammatory responses against pathogens to driving a number of autoimmune diseases. Accumulating evidence indicates that specific cellular lipid metabolic pathways that include fatty acid or cholesterol play an essential role in regulating the differentiation and function of Th17 cells. However, what molecular mechanisms link lipid metabolism and RORgt function during Th17-cell differentiation? By using a combination of a CRISPR- based screening system and a global lipidome analysis, we addressed this question in an effort to identify a specific lipid metabolite that is essential for RORgt-mediated Th17-cell differentiation. We found five lipid enzymes that elicit RORgt activity and constitute a core molecular signature of Th17 cells. Furthermore, although Th17 cells treated with TOFA, which is a ACC1 inhibitor, showed decreased mRNA expression of Th17 specific gene and chromatin accessibility at Th17 cell specific gene loci, we also found that extrinsic supplementation of LPE (1-18:1) restored the phenotype of ACC1-inhibited Th17 cells. Taken together, these series of results indicated that LPE (1-18:1) synthesized from the five lipid metabolic enzymes was required for RORgt to function appropriately in Th17-cell differentiation.
Project description:Full development of IL-17 producing CD4+ T helper cells (TH17 cells) requires the transcriptional activity of both orphan nuclear receptors RORa and RORgt. Despite this evidence, RORa is considered functionally redundant to RORgt; thus, the function and therapeutic value of RORa in TH17 cells remains underexplored. Using mouse models of autoimmune and chronic inflammation, we show that expression of RORa is required for TH17 cell pathogenicity. T-cell specific deletion of RORa reduced the development of experimental autoimmune encephalomyelitis (EAE) and colitis. Reduced inflammation was associated with decreased TH17 cell development, lower expression of tissue-homing chemokine receptors and integrins, and increased frequencies of Foxp3+ T regulatory (Treg) cells. Importantly, inhibition of RORa with a selective small molecule antagonist largely phenocopied our genetic data, potently suppressing the in vivo development of both chronic/progressive and relapsing/remitting EAE but had no effect on overall thymic cellularity. Furthermore, use of the RORa antagonist effectively inhibited human TH17 cell differentiation and memory cytokine secretion. Together, these data suggest that RORa acts independently of RORgt in programming TH17 pathogenicity and identifies RORa as a safer and more selective therapeutic target for the treatment of TH17-mediated autoimmunity.
Project description:T helper 17 (Th17) cells produce interleukin-17 (IL-17) cytokines and drive inflammatory responses in autoimmune diseases such as multiple sclerosis and rheumatoid arthritis. The differentiation of Th17 cells is dependent on the retinoic acid receptor-related orphan nuclear receptor RORgt. Here we identify REV-ERBa (encoded by Nr1d1), a member of the nuclear hormone receptor family (NHR), as a transcriptional repressor that antagonizes RORgt function in Th17 cells. REV-ERBa binds to ROR response elements (RORE) in Th17 cells and inhibits the expression of RORgt-dependent genes such as Il17a and Il17f. Furthermore, elevated REV-ERBa expression or treatment with a synthetic REV-ERB agonist significantly delays the onset and impedes the progression of experimental autoimmune encephalomyelitis (EAE), a Th17 cell-mediated autoimmune disease. These results suggest that modulating REV-ERB activity may hold therapeutic potential for treatment of Th17 cell-mediated autoimmune diseases.