Effects of Secreted Mast Cell Mediators on Retinal Pigment Epithelial Cells: Focus on Mast Cell Tryptase.

Rei Arai,Nobuyuki Ebihara,Yosuke Ito,Akira Murakami,Keitaro Mashimo,Ayumi Usui-Ouchi

doi:10.1155/2017/3124753

Rei Arai, Nobuyuki Ebihara + Show 4 more

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https://doi.org/10.1155/2017/3124753

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Abstract

Numerous mast cells are present in the choroid, but the effects of mast cell mediators on retinal pigment epithelial (RPE) cells are not well understood. We investigated the influence of mast cell mediators on RPE cells in vitro, focusing on tryptase. Expression of receptors was examined by the reverse transcription polymerase chain reaction. We also assessed production of interleukin 8 and vascular endothelial growth factor (VEGF) after RPE cells were stimulated with mast cell mediators by using an antibody array and enzyme-linked immunosorbent assay. Furthermore, we investigated the influence of tryptase on RPE cell migration and integrity by the scratch assay and the transepithelial resistance. RPE cells expressed protease-activated receptor 2 (PAR2), histamine receptor 1, tumor necrosis factor-α (TNF-α) receptor 1, and CCR 1, 3, 4, 8, and 11. Tryptase, PAR2 agonists, histamine, and TNF-α all enhanced interleukin 8 production by RPE cells, while only tryptase enhanced VEGF production. Tryptase also enhanced expression of phosphorylated extracellular signal-regulated kinases 1/2, resulting in increased migration of RPE cells. However, tryptase did not alter epithelial integrity or the expression of zonula occludens-1 and junctional adhesion molecule-A by RPE cells. Mast cell mediators, especially tryptase, may influence RPE cell inflammation.

Highlights

Mast cells are abundant in the choroid, whereas only a few of these cells are found in the anterior uvea
We examined the expression of protease-activated receptor 2 (PAR2), histamine receptor 1 (HR1), and tumor necrosis factor-α (TNF-α) receptor 1 (TNF-αR1) by employing appropriate primers for reverse transcription polymerase chain reaction (RT-PCR) (Table 1)
Immunocytochemistry revealed that incubation with tryptase (2.2 nM) for 4 or 24 h did not alter the expression of zonula occludens-1 (ZO-1) or junctional adhesion molecule-A (JAM-A) by retinal pigment epithelial (RPE) cell monolayers, which corresponded to the findings for transepithelial resistance (TER) (Figure 10)

Summary

Introduction

Mast cells are abundant in the choroid, whereas only a few of these cells are found in the anterior uvea. It was reported that most choroidal mast cells belong to the TC subtype with granules containing both chymase and tryptase, and this was confirmed by investigation of choroidal mast cell suspensions [1,2,3, 5]. Numerous mast cells capable of releasing various mediators reside in the inner vascular layer of the choroid. We investigated the effects of various mast cell mediators on retinal pigment epithelial (RPE) cells in vitro. We assessed the effect of mast cell mediators, tryptase, on the production of interleukin 8 (IL-8) and vascular endothelial growth factor (VEGF) by RPE cells, by using an antibody array and enzyme-linked immunosorbent assay (ELISA). We examined the effect of tryptase on epithelial integrity and expression of tight junction-related proteins by RPE cells by measurement of transepithelial resistance (TER) and immunocytochemistry. To the best of our knowledge, this is the first report about the effects of mast cell mediators, tryptase, on RPE cells

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Discussion