Functionally distinct IFN‐γ+IL‐17A+ Th cells in experimental autoimmune uveitis: T‐cell heterogeneity, migration, and steroid response

摘要

Abstract Immunopathogenic roles for both Th1 (CD4+IFN‐γ+) and Th17 (CD4+IL‐17A+) cells have been demonstrated in experimental autoimmune uveitis (EAU). However, the role for Th17/Th1 (CD4+ T cells co‐expressing IFN‐γ and IL‐17A) cells in EAU is not yet understood. Using interphotoreceptor retinoid‐binding protein peptide‐induced EAU in mice, we found increased levels of Th17/Th1 cells in EAU retinae (mean 9.6?±?4.2%) and draining LNs (mean 8.4?±?3.9%; p?=?0.01) relative to controls. Topical dexamethasone treatment effectively reduced EAU severity and decreased retinal Th1 cells (p?=?0.01), but had no impact on retinal Th17/Th1 or Th17 cells compared to saline controls. Using in vitro migration assays with mouse CNS endothelium, we demonstrated that Th17/Th1 cells were significantly increased within the migrated population relative to controls (mean 15.6?±?9.5% vs. 1.9?±?1.5%; p?=?0.01). Chemokine receptor profiles of Th17/Th1 cells (CXCR3 and CCR6) did not change throughout the transendothelial migration process and were unaffected by dexamethasone treatment. These findings support a role for Th17/Th1 cells in EAU and their resistance to steroid inhibition suggests the importance of targeting both Th17 and Th17/Th1 cells for improving therapy.