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Ana Ramirez, Jose A. Fernández-Albarral, Inés López Cuenca, Elena Salobrar-García, Pilar Rojas, Rosa de Hoz, Marcelino Avilés-Trigueros, Manuel A Vidal-Sanz, Jose Ramirez, Juan J. Salazar; Microglial activation in healthy retina and experimental glaucoma during aging.. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2370.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify morphological signs of microglial cell activation and P2RY12, MHC-II and CD68 expression in aged mice (15 month) compared to young adult mice (3 month) and after unilateral laser-induced ocular hypertension (OHT).
Albino Swiss mice were divided in four groups: young naïve (YN, n=6), aged naïve (AN, n=6), young OHT (YG, n=6), and aged OHT (AG, n=6). In OHT groups both eyes (OHT and contralateral) were studied. Retinal whole-mounts were immunolabeled with anti Iba-1 to quantify: i) Iba-1 + cells number (Ibacn) in outer segments (OS), outer plexiform layer (OPL) and inner plexiform layer (IPL); ii) area of retina occupied by Iba-1 + cells (Iba-1 RA) in the nerve fiber layer- ganglion cell layer (NFL-GCL): iii) cell body area of Iba-1+ cells (CbIbac) in OPL, IPL and NFL-GCL; iv) arbor area of Iba-1+ cells (AAIbac) in OPL and IPL; and v) vertical processes number of Iba-1+ cells (VPIbac) between OS and OPL. Antibodies against P2RY12 (resident microglia), CD68 (phagocytic activity) and MHC-II (microglial activation marker) were also used.
In AN respect to YN the quantitative analysis showed a significant increase in the Cbibac in OPL, IPL and NFL-GCL and a significant increase in the VPibac. Both OHT eyes and contralateral eyes of YG and AG showed significant increase of Ibacn, Iba-1 RA, CbIbac and VPIbac and decrease of AAIbac, more pronounced in OHT eyes, compared to their respective naïve groups. Comparing AG vs YG showed: i) a significant decrease of Iba-1 RA and VPIbac in OHT eyes; ii) a significant increase of Ibacn (OS) and a significant decrease of CbIbac and AAIbac (IPL), in contralateral eyes. Analyzing the P2RY12, CD68 and MHC-II expression we observed: i) in YN and in YG all Iba-1+ cells were P2RY12+, except perivascular and dendritic cells, but in AG most cells were Iba-1+/P2RY12- and some cells in AN; ii) in AN, AG and YG numerous amoeboid-like CD68+ cells were found but in AG CD68+ cells with ramified appearance were also observed. In YG practically all Iba-1+ cells were MHC-II+, while in GA only some Iba-1+ cells were MHC-II+. However, in YN and AN Iba-1+ cells were MHCII-.
The morphological and expression differences of P2RY12, CD68 and MHC-II found in the microglial cells of AN and AG compared to those of YN and YG show that aging can increase the inflammatory process in glaucoma.
This is a 2021 ARVO Annual Meeting abstract.
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