P2RY12 expression at different time‐points in a mouse model of experimental glaucoma

Abstract

AbstractPurposeDown‐regulation of P2RY12 after injury constitutes a sensitive marker for the transition from resting to activate microglia. P2RY12 is expressed by microglia but not by monocytes, infiltrating macrophages or dendritic cells, thus can used to identify resident microglia. Thus, the aims of the study is to determine the P2RY12 expression on retinal Iba‐1+ cells after unilateral laser‐induced ocular hypertension (OHT) in OHT‐eyes and their contralateral eyes, at different time points (1, 3, 5, 8 and 15 days) and in the different retinal layers such as outer segments (OS), outer plexiform layer (OPL), inner plexiform layer (IPL) and the complex nerve fiber layer‐ganglion cell layer (NFL‐GCL)), after unilateral laser‐induced ocular hypertension (ULOHT) in OHT‐eyes and their contralateral eyes.MethodsAlbino Swiss mice were divided into two groups, naïve and lasered. In this last group OHT, eyes and their contralateral eyes were studied. Retinal whole‐mounts were double‐immunostained with Iba1 and P2RY12 antibodies.ResultsIn naïve eyes, Iba‐1+ cells expressed P2RY12, with the exception of perivascular microglia and dendritic‐like Iba‐1+ cells in all retinal layers analyzed. In OHT eyes, at 24 h and 15 d after laser induction, most Iba‐1+ cells showed high P2RY12 expression in the OS, OPL, IPL and NFL‐GCL, except some rounded cells in the OS and NFL‐GCL and very few ramified cells in the IPL and NFL‐GCL. At intermediate times (3 d and 5 d), P2RY12 expression was dramatically lower than at 1d in all retinal layers. Expression increased weakly at 8 d, reaching values similar to those in naïve eyes at 15 d. In contralateral eyes, as in naïve ones, Iba‐1+ cells were intensely labelled with anti‐P2RY12 in all retinal layers at all‐time points analyzed.ConclusionMost of Iba‐1+ cells in the OHT eyes and contralateral eyes at the different time‐points were microglia, as demonstrated by their P2RY12 expression. P2RY12 expression is reduced after microglial activation indicating that 3 d and 5 d were the point‐times in which the microglial activation was maximal.AcknowledgementThis work was supported by Ophthalmological Network OFTARED (RD12‐0034/0002 and RD12/0034/0014. Prevención, Detección Precoz y Tratamiento de la Patología Ocular Prevalente Degenerativa y Crónica), the Institute of Health of Carlos III of the Spanish Ministry of Economy; PN I+D+i 2008‐2011; ISCIII, General Subdirection of Networks and Cooperative Research Centers; by the FEDER European program. Grants to J.A. Fernández‐Albarral are currently supported by a Predoctoral Fellowship (FPU) from the Spanish Ministry of Science, Innovation and University.