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R. W. Lee, H. Sen, Z. Li, L. P. Schewitz-Bowers, A. D. Dick, R. B. Nussenblatt, L. Wei; Gene Expression and Epigenomic Profiling of Th17 Cells in Steroid Refractory Uveitis. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2922.
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© ARVO (1962-2015); The Authors (2016-present)
Patients with steroid refractory (SR) uveitis have a characteristic subpopulation of SR CD4+ T cells in their peripheral blood. We have previously demonstrated that this SR phenotype is restricted to the central memory pool of CD4+ cells which have the capacity to generate IL-17. We therefore interrogated the transcriptomic and epigenomic responses of Th17 cells to corticosteroids in order to identify novel biomarkers and targets for therapeutic intervention in steroid refractory disease.
CD4+CCR6+ and CD4+CCR6- cells isolated from the PBMCs of patients with SR and steroid sensitive (SS) uveitis were cultured for 2 weeks in Th17 versus Th1 polarizing conditions prior to treatment with 10-6M Dexamethasone (Dex). Differences in gene expression were analysed by microarray (Affymetrix). Genome-wide H3K4me3 and H3K27me3 maps were generated by chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq, Illumina).
IL-17 production was greater in CD4+CCR6+ cells cultured in Th17 conditions from SR patients (49.5% vs 10.6% / SR vs SS). However, principal component analysis demonstrated that once generated, Th17 cells from either SR or SS patients had an equally restricted response to Dex compared to Th1 cells. Key upregulated transcripts in SR Th17 cultures exposed to Dex were FKBP5, CXCL13 and IL7R. Downregulated transcripts included IL22, CD160 and IL23R. Histone modification changes were associated with altered gene expression.
SR patients have a greater propensity than SS patients to generate Th17 cells, but Th17 cells from either group of patients have a similarly restricted change in gene expression following exposure to Dex compared with Th1 cells. Our transcriptome and epigenome data provide candidate biomarkers for differing steroid responses between patients, and also suggest an epigenetic mechanism underlying steroid refractory diseases.
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