IOP Induces MHC-II Overexpression In Microglia And Macroglia In Contralateral Mice Retina To Experimental Glaucoma

Abstract

Purpose: : To analyze the effects of laser-induced ocular hypertension (OHT) in MHC-II expression in the macro- and microglia of eyes with OHT (OHT-eyes) and contralateral eyes two weeks after lasering.

Methods: : Adult Swiss mice were divided into two groups: naïve (n=6) and lasered (n=6). Retinal wholemounts were immunostained with antibodies against GFAP, Iba-1 and MHC-II.

Results: : In the naïve retinas, weak constitutive MHC-II expression was scarcely found in some Iba-1+ microglial cells and rarely in GFAP+ astrocytes. Only a small dendritiform subpopulation of Iba-1+ cells, located in the juxtapapillary area and in the marginal region of the retina, had a strong MHC-II immunoreaction. In comparison to naïve results, MHC-II in the contralateral eye was expressed in Müller cells and was overexpressed in Iba-1+ cells- and astrocytes. Thus, in contralateral macroglia, MHC-II was preferentially expressed by astrocytes. In OHT-eyes, Iba-1+ cells showed MHC-II immunoreactivity similar to contralateral and no MHC-II astrocytes were observed; however, MHC-II expression was upregulated in several groups of Müller cells throughout the retina and was preferentially located in the end-foot of the cells.

Conclusions: : Two weeks of laser-induced OHT caused macro- and microglial retinal changes in MHC-II expression both in contralateral and in OHT-eyes. Our results suggest that the gliotic behaviour in contralateral untreated eyes could be related to the immune response. On the basis of the glial changes observed, the use of the contralateral eye as a control in experimental unilateral OHT should be reconsidered.

Keywords: retinal glia • inflammation • immunohistochemistry