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

Abstract

PURPOSE: Müller glia play dual roles in glaucoma, contributing to retinal homeostasis and neuroinflammation; activation by elevated intraocular pressure through mechanosensitive transient receptor potential vanilloid 4 (TRPV4) promotes a reactive state that drives retinal ganglion cell loss. Lipoxin B4 (LXB4), an endogenous lipid mediator produced by retinal astrocytes, suppresses glial reactivity and protects retinal ganglion cells. This study investigated whether LXB4 modulates TRPV4-driven Müller glial activation and whether Müller glia contribute to the lipoxin pathway. METHODS: Ocular hypertension was induced in mice via a silicone oil model, and reactive Müller glia were isolated by magnetic sorting for transcriptomics. In vitro, Müller glia cultures were treated with a TRPV4 agonist with or without LXB4. Glial reactivity was assessed by flow cytometry, immunostaining, qPCR, and Western blotting. Lipidomics quantified pathway metabolites, and single-cell RNA sequencing examined transcriptional responses to LXB4. RESULTS: Bulk RNA sequencing and qPCR revealed Müller glia express 5- and 15-lipoxygenase. Lipidomics confirmed a functional pathway, with endogenous LXB4 production, identifying Müller glia as a source of neuroprotective LXB4. TRPV4 activation induced gliosis with increased glial fibrillary acidic protein, IL-6, and signal transducers and activators of transcription 3 (STAT3) expression, and lipoxin production, indicating biomechanical stress triggers reactivity and protective signaling. LXB4 suppressed TRPV4-induced gliosis in vitro by downregulating IL-6 and STAT3 and in vivo by reducing Stat3, Il6, and Tnf-α and attenuating TRPV4 upregulation during ocular hypertension. CONCLUSIONS: 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. These findings support the targeting of the TRPV4-lipoxin pathway as a potential approach to protect against ocular hypertension-induced neurodegeneration in glaucoma.