Hydrocortisone Suppression of the Expression of VEGF May Relate to Toll-Like Receptor (TLR) 2 and 4

Purpose: The purpose of this study was to investigate hydrocortisone's potential in inhibiting the expression of VEGF in cultured human cornea fibroblasts (HCF) and to determine whether the role of hydrocortisone in the expression of VEGF may relate to toll-like receptors 2 and 4 (TLR2 and TLR4). Methods: Three different concentrations of hydrocortisone were used to stimulate the cultured HCF. The cellular abundance of the mRNAs for VEGF and TLR2, 4 were determined by real-time polymerase chain reaction analysis. The release of IL-6, IL-8, and VEGF from cultured HCF was measured using enzyme-linked immunosorbent assays (ELISA) in the presence and absence of specific blocking antibodies to TLR2, 4. The proteins of TLR2, 4 were also compared by Western blot. Results: Following incubation of HCF with hydrocortisone, we found the mRNA expression of TLR2, 4 and VEGF were markedly inhibited. ELISA and Western blot analysis confirmed that protein expression of TLR2, 4 and VEGF was down-regulated in response to hydrocortisone. The result of ELISA also showed the release of IL-6 and IL-8 can be inhibited by hydrocortisone. But all these inhibitions were partly counteracted after pretreatment with anti-TLR2 and/or anti-TLR4 monoclonal antibody. Conclusions: Hydrocortisone may decrease the expression of VEGF through inhibiting TLR2, 4 activity in cultured human corneal fibroblasts.