Topical ROCK inhibitor Ripasudil (K-115) attenuates M1-like macrophages in the mouse model of oxygen-induced retinopathy

Abstract

Purpose : It has been reported that macrophages are made up of at least two phenotypes, classically activated macrophages (M1) and alternatively activated macrophages (M2), and the phenotypic change is known to contribute to the pathogenesis of various diseases. We previously reported a Rho-associated coiled coil–containing protein kinase (ROCK) inhibitor ripasudil (K-115) eye drop could cause vascular normalization in in the mouse model of oxygen-induced retinopathy (OIR). In this study, we investigated the impact of ROCK inhibitor ripasudil (K-115) eye drop on M1 and M2 macrophages in the model.

Methods : Mice were reared in a 75±2% oxygen air from P7, and then moved into room air on P12. Then, a physiological saline solution or a 0.8% ripasudil ophthalmic solution was applied to both eyes 3 times daily for 5 days (P12–P16). Quantitative RT-PCR and immunofluorescence staining were used to assess the different macrophage markers at P 17.

Results : Quantitative RT-PCR showed various significant elevation of macrophages markers in OIR retina and significant reduced M1 markers (CD80 and NOS2) in ripasudil-treated retina compared with saline-treated one (CD80; p=0.02 vs normal saline, NOS2; p<0.01 vs normal saline). Ripasudil did not show apparent impact on the expression of M2 marker CD206. Immunohistochemistry also confirmed the decreased number of CD80-positive M1-like macrophages in the avascular area of ripasudil-treated OIR retina.

Conclusions : Topical ripasudil treatment could attenuate M1-like macrophages in hypoxic retina.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.