Lipoxin B₄ Mitigates TRPV4-Activated Müller Cell Gliosis During Ocular Hypertension

Müller glia play dual roles in glaucoma, contributing to both retinal homeostasis and neuroinflammation; their activation by elevated intraocular pressure through the mechanosensitive channel TRPV4 promotes a reactive state that drives retinal ganglion cell (RGC) loss. Lipoxin B₄ (LXB₄), an endogenous lipid mediator produced by retinal astrocytes, has been shown to suppress glial reactivity and directly protect RGCs. This study investigated whether LXB₄ modulates TRPV4-driven Müller glial activation and inflammation and whether Müller glia themselves contribute to this retinal lipoxin pathway.

Ocular hypertension (OHT) was induced in mice via a silicone oil model, and reactive Müller glia were isolated via magnetic sorting for transcriptomic analysis. In vitro, primary and immortalized Müller glia were treated with a TRPV4 agonist with or without LXB₄. Glial reactivity was assessed by flow cytometry, immunostaining, qPCR, and western blotting. LC-MS/MS-based lipidomics was used to quantify lipoxin pathway metabolites, and single-cell RNA-seq was used to examine transcriptional responses to LXB₄ treatment. GFAP and TRPV4 expression was evaluated via immunohistochemistry in retinal sections.

RNA bulk-sequencing analysis and qPCR revealed that Müller glia express both 5- and 15-lipoxygenase. Lipidomic analysis confirmed that the lipoxin pathway is functional and that Müller glia endogenously produce LXB₄, establishing this essential cell type as a source of anti-inflammatory and neuroprotective LXB₄ in the retina. TRPV4 activation induced a reactive glial phenotype characterized by increased GFAP and IL6 expression, increased STAT3 phosphorylation, and increased production of lipoxins, suggesting that biomechanical stress simultaneously triggers both gliosis and protective lipid signaling. Treatment with LXB₄ suppressed TRPV4-induced gliosis in vitro by downregulating IL6 and inhibiting STAT3 activation, and in vivo by reducing the expression of Stat3, Il6, and TNF-α during OHT while attenuating TRPV4 upregulation in Müller glia.

Müller glia are a significant source of LXB₄ in the retina. This neuroprotective Müller glia pathway is amplified during chronic TRPV4 activation to counter-regulate gliosis. The findings support targeting of the TRPV4-lipoxin pathway as a potential approach to protect against OHT-induced neurodegeneration in glaucoma.