Abstract
Purpose:
Numerous mast cells are present in the choroid. Although mast cells are known to be involved in inflammatory responses, their role in choroidal inflammation is not well understood. In this study, we investigated the influence of mast cell mediators on retinal pigment epithelial cells (RPE cells) in vitro.
Methods:
Initially, we observed human choroidal tissues by light microscopy. Next, we examined the expression of receptors for mast cell mediators on RPE cells by RT-PCR analysis. We also assessed the production of IL-8 and VEGF after RPE cells were stimulated with mast cell conditioned medium or various mast cell mediators using an antibody array and ELISA. Furthermore, we investigated the influence of tryptase on the migration of RPE cells by the scratch assay. Finally, we examined stem cell factor (SCF) expression in RPE cells by RT-PCR and ELISA.
Results:
Many connective tissue type mast cells were observed in the choroid. RPE cells expressed protease-activated receptor 2 (PAR2), histamine R1, TNF-α R1, and CCR 1, 3, 4, 8, and 11. Mast cell conditioned medium, tryptase, PAR2 agonists, histamine, and TNF-α all enhanced IL-8 production by RPE cells, while only tryptase enhanced the production of VEGF. Tryptase also enhanced phosphorylated ERK 1/2 expression, resulting in increased migration of RPE cells. Moreover, RPE cells expressed SCF.
Conclusions:
Cross-talk between mast cells and RPE cells via secreted mediators, especially tryptase, may have a crucial role in choroidal inflammation.
Keywords: 701 retinal pigment epithelium •
557 inflammation