Tumor Necrosis Factor Alpha-Mediated Interaction Between Microglia and Müller Cells Exacerbates Retinal Ganglion Cell Damage in Experimental Glaucoma.

Interaction between Müller cells and microglia aggravates neuroinflammation, resulting in retinal ganglion cell (RGC) death in glaucoma. Here, we investigated how tumor necrosis factor-alpha (TNF-α) produced by activated microglia mediates the crosstalk between Müller cells and microglia and impacts RGC injury in a chronic ocular hypertension (COH) glaucoma model. In COH retinas, elevated TNF-α induced the activation of Müller cells and microglia, and recruited microglia to the ganglion cell layer. Co-culture with Müller cells enhanced TNF-α-induced microglial activation, migration, and proliferation. Both in vivo and in vitro experiments confirmed that chemokine C-C motif ligand 2 (CCL2), primarily released from Müller cells, mediated the TNF-α-induced effects on microglia in COH retinas. Knockdown of CCL2 attenuated RGC damage and vision loss. Our results demonstrate that TNF-α released from microglia induces the secretion of CCL2 from Müller cells, thus inducing microglial activation and migration, exacerbating retinal neuroinflammation and RGC injury in glaucoma.