Changes in cytokine and growth factor levels at different time points after experimental glaucoma induction.

Abstract

Purpose : To quantify the expression of different cytokines (IL-1β, IL-4, IL-6, IL-10, IL-17, IFN-γ), neurotrophic factors (BDNF, VEGF) and Fractalkine (CX3CL), released by retinal glial cells, at different times after unilateral laser-induced ocular hypertension (OHT), both in OHT eyes and their contralateral eyes respect to naïve eyes.

Methods : Six groups of albino Swiss mice (a naïve group and five OHT groups) were analyzed. Animals were sacrificed at different time-points after OHT laser induction ( 1, 3, 5, 7 and 15 days) and both treated OHT eye and contralateral untreated eye were studied. The samples obtained were processed in two different ways: i) multiarray kits (MILLIPLEX MAP Mouse Cytokine/Myokine Magnetic Bead Panel) were used to quantify the expression of cytokines, and ii) Double immunolabelling were performed in retinal sections to determinate which cells expressed the different molecules analyzed. In multiplexed study 12 animals per group were used and 5 animals in each group for immunohistochemistry study.

Results : Compared to naïve, in OHT eyes, were observed a significant increase in the expression of : i) IFN-γ at 3, 5 and 15 days; ii) IL-4 at 1, 3, 5 and 7 and IL-10 at 3 and 5 days (which coincided with the downregulation of IL1-β at days 1, 5, and 7); iii) IL-6 at 1, 3 and 5 days; iv) VEGF and Fractalkine at 1 day; and v) BDNF at 1, 3, 7 and 15 days. In contralateral eyes, the significant changes were: i) increase of IL-1β at 1 and 3 days and decrease at 7 day ( which coincided with the downregulation of IL-4 at 3 and 5 days and the upregulation at 15 days); ii) increase of IL-6 at 1, 5 and 7 days and decrease at 15 days; iii) increase of IL-10 at 3 and 7 days; and iv) increase of IL-17 at 15 days. Immunohistochemical study shown that microglia expressed IL-1β, IFN-γ, IL-4, IL-6, IL-17 and fractalkine, and that the macroglia (astrocytes and Müller) expressed IL-1β, BDNF and VEGF. IL-10 were expressed by retinal ganglion cells axons.

Conclusions : Unilateral laser-induced ocular hypertension causes changes in the expression of anti- and pro-inflammatory molecules associated with inflammatory process, mainly 3 days after OHT induction, both in OHT eyes and in contralateral eyes, which may confirm the implication of the immune system in glaucoma.

This is a 2021 ARVO Annual Meeting abstract.