The immunoregulatory role of corneal epithelium-derived thrombospondin-1 in dry eye disease.

PURPOSE: In this study, we examine the expression of corneal epithelium-derived thrombospondin-1 (TSP-1) and its immunomodulatory functions in a validated murine model of dry eye disease (DED). METHODS: DED was induced in female C57BL/6 using a controlled environment chamber (CEC) for 14 days. mRNA and protein expression of TSP-1 by corneal epithelial cells was quantified using real-time PCR and flow cytometry. Corneal epithelial cells from either naïve or DED mice were cultured with bone marrow derived dendritic cells (BMDCs) in the presence of IFNγ for 48 h, and BMDC expression of MHC-II and CD86 was determined using flow cytometry. Next, either recombinant TSP-1 or anti-TSP-1 antibody was added to the co-culture, and BMDC expression of above activation markers was evaluated. Finally, either DED mice were topically treated with either recombinant TSP-1 or human serum albumin (HSA), and maturation of corneal DCs, expression of inflammatory cytokines, and DED severity were investigated. RESULTS: mRNA expression of TSP-1 by the corneal epithelium was upregulated in DED. Corneal epithelial cells derived from mice with DED demonstrated an enhanced capacity in suppressing BMDC expression of MHC-II and CD86 relative to wild type mice, and this effect was abrogated by TSP-1 blockade and potentiated by recombinant TSP-1. Finally, topical application of recombinant TSP-1 significantly suppressed corneal DC maturation and mRNA expression of pro-inflammatory cytokines, and ameliorated disease severity in mice with DED. CONCLUSIONS: Our study elucidates the function of epithelium-derived TSP-1 in inhibiting DC maturation and shows its translational potential to limit corneal epitheliopathy in DED.