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Oxysterols are agonist ligands of ROR?t and drive Th17 cell differentiation.

ABSTRACT: The RAR-related orphan receptor gamma t (ROR?t) is a nuclear receptor required for generating IL-17-producing CD4(+) Th17 T cells, which are essential in host defense and may play key pathogenic roles in autoimmune diseases. Oxysterols elicit profound effects on immune and inflammatory responses as well as on cholesterol and lipid metabolism. Here, we describe the identification of several naturally occurring oxysterols as ROR?t agonists. The most potent and selective activator for ROR?t is 7?, 27-dihydroxycholesterol (7?, 27-OHC). We show that these oxysterols reverse the inhibitory effect of an ROR?t antagonist, ursolic acid, in ROR?- or ROR?t-dependent cell-based reporter assays. These ligands bind directly to recombinant ROR? ligand binding domain (LBD), promote recruitment of a coactivator peptide, and reduce binding of a corepressor peptide to ROR? LBD. In primary cells, 7?, 27-OHC and 7?, 27-OHC enhance the differentiation of murine and human IL-17-producing Th17 cells in an ROR?t-dependent manner. Importantly, we showed that Th17, but not Th1 cells, preferentially produce these two oxysterols. In vivo, administration of 7?, 27-OHC in mice enhanced IL-17 production. Mice deficient in CYP27A1, a key enzyme in generating these oxysterols, showed significant reduction of IL-17-producing cells, including CD4(+) and ??(+) T cells, similar to the deficiency observed in ROR?t knockout mice. Our results reveal a previously unknown mechanism for selected oxysterols as immune modulators and a direct role for CYP27A1 in generating these ROR?t agonist ligands, which we propose as ROR?t endogenous ligands, driving both innate and adaptive IL-17-dependent immune responses.

SUBMITTER: Soroosh P

PROVIDER: S-EPMC4143045 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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Oxysterols are agonist ligands of RORγt and drive Th17 cell differentiation.

Soroosh Pejman P Wu Jiejun J Xue Xiaohua X Song Jiao J Sutton Steven W SW Sablad Marciano M Yu Jingxue J Nelen Marina I MI Liu Xuejun X Castro Glenda G Luna Rosa R Crawford Shelby S Banie Homayon H Dandridge Rose A RA Deng Xiaohu X Bittner Anton A Kuei Chester C Tootoonchi Mandana M Rozenkrants Natasha N Herman Krystal K Gao Jingjin J Yang Xia V XV Sachen Kacey K Ngo Karen K Fung-Leung Wai-Ping WP Nguyen Steven S de Leon-Tabaldo Aimee A Blevitt Jonathan J Zhang Yan Y Cummings Maxwell D MD Rao Tadimeti T Mani Neelakandha S NS Liu Changlu C McKinnon Murray M Milla Marcos E ME Fourie Anne M AM Sun Siquan S

Proceedings of the National Academy of Sciences of the United States of America 20140804 33

The RAR-related orphan receptor gamma t (RORγt) is a nuclear receptor required for generating IL-17-producing CD4(+) Th17 T cells, which are essential in host defense and may play key pathogenic roles in autoimmune diseases. Oxysterols elicit profound effects on immune and inflammatory responses as well as on cholesterol and lipid metabolism. Here, we describe the identification of several naturally occurring oxysterols as RORγt agonists. The most potent and selective activator for RORγt is 7β, ...[more]

PMID: 25092323

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Project description:CD4+ T helper lymphocytes that express interleukin-17 (Th17 cells) have critical roles in mouse models of autoimmunity, and there is mounting evidence that they also influence inflammatory processes in humans. Genome-wide association studies in humans have linked genes involved in Th17 cell differentiation and function with susceptibility to Crohn’s disease, rheumatoid arthritis, and psoriasis1-3. Thus, the pathway towards differentiation of Th17 cells and, perhaps, of related innate lymphoid cells with similar effector functions4, 5, is an attractive target for therapeutic applications. Mouse and human Th17 cells are distinguished by expression of the retinoic acid receptor-related orphan nuclear receptor RORγt, which is required for induction of IL-17 transcription and for the manifestation of Th17-dependent autoimmune disease in mice6. By performing a chemical screen with an insect cell-based reporter system, we identified the cardiac glycoside digoxin as a specific inhibitor of RORγt transcriptional activity. Digoxin inhibited murine Th17 cell differentiation without affecting differentiation of other T cell lineages and was effective in delaying the onset and reducing the severity of autoimmune disease in mice. At high concentrations, digoxin is toxic for human cells, but non-toxic synthetic derivatives, 20,22-dihydrodigoxin-21,23-diol (Dig(dhd)) and digoxin-21-salicylidene (Dig(sal)), specifically inhibited induction of IL-17 in human CD4+ T cells. Using these small molecule compounds, we demonstrated that RORγt is imporant for the maintenance of IL-17 expression in mouse and human effector T cells. These data suggest that derivatives of digoxin can be used as chemical probes for development of RORγt-targeted therapeutic agents that attenuate inflammatory lymphocyte function and autoimmune disease. We performed gene expression profiling with total RNA samples isolated from DMSO- or digoxin-treated wildtype or RORγt-deficient cells cultured in Th17 conditions. Total RNA was extracted with TRIzol. RNA was labeled and hybridized to GeneChip Mouse Genome 430 2.0 arrays following the Affymetrix protocols. Data were analyzed in GeneSpring GX11.5.

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Oxysterols are agonist ligands of ROR?t and drive Th17 cell differentiation.

Publications

Oxysterols are agonist ligands of RORγt and drive Th17 cell differentiation.

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