TRPV4 antagonist reduced the formation of retinal edema in a murine model of retinal vein occlusion

Abstract

Purpose : Retinal vein occlusion (RVO) is a leading cause of visual loss due to retinal vascular disease. Retinal ischemia promotes the production of proinflammatory cytokines, such as vascular endothelial growth factor (VEGF) and tumor necrosis factor-α (TNF-α), which induce the breakdown of the blood retinal barrier (BRB). Anti-VEGF treatments are used for patients with retinal vein occlusion (RVO), but some patients exhibit resistance to current anti-VEGF therapies or develop rebound edema. The aim of the present study is to evaluate a novel Transient Receptor Potential Vanilloid 4 (TRPV4) antagonist, RQ-00317310, on vascular permeability and retinal edema in the RVO model.

Methods : RVO was induced by tail vein injection of Rose Bengal, followed by photocoagulation (wavelength: 532 nm, power: 50 mW, duration: 5 s, spot size: 50 μm) in male ddY mice. The expression levels of TRPV4 were analyzed by Western blot and immunofluorescence. To examine the role of TRPV4 in a murine RVO model, RQ-00317310 was injected intravitreally (2 µL/eye). After intravitreal injection of TRPV4 antagonist, the effects on an RVO model were determined by the measurements of retinal edema, ocular blood flow, and Western blot. The retinal nonperfusion area was visualized by tail vein injection of fluorescein isothiocyanate (FITC)-labeled dextran (2,000 kDa). Endothelial barrier integrity was measured by trans-epithelial electrical resistance (TEER) value in human retinal microvascular endothelial cells (HRMEC).

Results : The TRPV4 expression was significantly increased and was colocalized with glutamine synthetase (GS) positive Müller cells in the retina of RVO model mice. RQ-00317310 (250 µM) significantly suppressed the formation of retinal edema and upregulation of TNF-α in the retina of the RVO model. The RVO-induced downregulation of a water ion channel, aquaporin 4 (AQP4), was also suppressed by RQ-00317310. Furthermore, RQ-00317310 improved ocular blood flow and the ischemic area in an RVO model. Endothelial permeability assay showed that both VEGF and TRPV4 agonist reduced the TEER values, in contrast, RQ-00317310 counteracted these dysfunctions in HRMEC.

Conclusions : These data suggested that TRPV4 is responsible for the BRB breakdown in ischemic retinopathy, and TRPV4 antagonist can be a novel therapeutic agent for hyperpermeability and retinal edema in RVO.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.