EphA4/ephrinA3 reverse signaling induced Müller cell gliosis and production of pro-inflammatory cytokines in experimental glaucoma

• Published in: Brain research 2023-02, Vol.1801, p.148204-148204, Article 148204
• Main Authors: Xu, Lin-Jie, Wang, Hong-Ning, Zhou, Han, Li, Shu-Ying, Li, Fang, Miao, Yanying, Lei, Bo, Sun, Xing-Huai, Gao, Feng, Wang, Zhongfeng
• Format: Article
• Language: English
• Subjects: Chronic ocular hypertension; Cytokines - metabolism; Ependymoglial Cells - metabolism; EphA4/ephrinA3 reverse signaling; Ephrin-A3 - metabolism; GFAP; Glaucoma; Gliosis - metabolism; Humans; Müller cells; Pro-inflammatory factors; Receptor, EphA4 - metabolism; Signal Transduction - physiology
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2022.148204

[Display omitted] •Activation of EphA4/ephrinA3 signaling induces Müller cell gliosis in COH retina.•STAT3 mediates the EphA4/ephrinA3 activation-induced Müller cell gliosis.•Activation of EphA4/ephrinA3 signaling increases pro-inflammatory factor release.•Activation of EphA4/ephrinA3 signaling enhances RGC apoptosis. Previous work showed that ephrinA3/EphA4 forward signaling contributed to retinal ganglion cell (RGC) damage in experimental glaucoma. Since up-regulated patterns of ephrinA3 and EphA4 were observed in Müller cells and RGCs, an EphA4/ephrinA3 reverse signaling may exist in Müller cells of chronic ocular hypertension (COH) retina. We investigated effects of EphA4/ephrinA3 reverse signaling activation on Müller cells in COH retina. Intravitreal injection of the ephrinA3 agonist EphA4-Fc increased glial fibrillary acidic protein (GFAP) levels in normal retinas, suggestive of Müller cell gliosis, which was confirmed in purified cultured Müller cells treated with EphA4-Fc. These effects were mediated by intracellular STAT3 signaling pathway as phosphorylated STAT3 (p-STAT3) levels and ratios of p-STAT3/STAT3 were significantly increased in both COH retinas and EphA4-Fc intravitreally injected retinas, as well as in EphA4-Fc treated purified cultured Müller cells. The increase of GFAP protein levels in EphA4-Fc-injected retinas and EphA4-Fc treated purified cultured Müller cells could be partially eliminated by stattic, a selective STAT3 blocker. Co-immunoprecipitation results testified to the presence of interaction between ephrinA3 and STAT3/p-STAT3. In addition, intravitreal injection of EphA4-Fc or EphA4-Fc treatment of cultured Müller cells significantly up-regulated mRNA and protein contents of pro-inflammatory cytokines. Moreover, intravitreal injection of EphA4-Fc increased the number of apoptotic RGCs, which could be reversed by the tyrosine kinase blocker PP2. Overall, EphA4/ephrinA3 reverse signaling may induce Müller cell gliosis and increases release of pro-inflammatory factors, which could contribute to RGC death in glaucoma. Inhibition of EphA4/ephrinA3 signaling may provide an effective neuroprotection in glaucoma.