Abstract
Purpose :
The conventional outflow pathway is regulated by complex and interactive signaling mechanisms that keep intraocular pressure (IOP) at a homeostatic level. This process is perturbed in patients with glaucoma. Our lab previously demonstrated that the mechanosensitive channels TRPV4 and TREK1 in trabecular meshwork (TM) cells are an ideal target for modulating the mechanisms that regulate IOP. However, it is unclear whether this mechanism is ubiquitous across different forms of glaucoma. Here, we sought to determine whether targeting TRPV4 and TREK1 are effective in a mouse model of steroid-induced glaucoma (SI-OHT).
Methods :
Primary mouse TM cells were isolated from WT and TRPV4cKO mice and exposed to media containing either vehicle or dexamethasone (DEX) for 5 days. A subset of WT mTM cells were treated with the TREK1 agonist, ML-402 concurrently with DEX exposure. Immunocytochemistry and qPCR were utilized to assess actin content and genetic expression of fibrotic and ECM regulators as well as mechanosensitive channels. To test the effect of TRPV4 and TREK1 on IOP regulation in vivo, mice were treated topically with DEX. After achieving stable IOP, mice were treated with HC-06 or ML-402 and IOP was measured after treatment.
Results :
DEX elevated the fluorescence intensity of the actin cytoskeleton and stress fiber formation. This change in the actin network was blocked by pharmacologically activating TREK1 or genetically ablating TRPV4. Similarly, DEX elevated mRNA expression levels of myocilin, fibrotic markers (e.g. S100A4), ECM regulators (e.g. MMP9) and decreased expression of mechanosensitive channels (e.g. TRPV4, TREK1). The DEX-induced alterations in gene expression were modulated by ablation and agonism of TRPV4 and TREK1, respectively. Topical administration of DEX to WT mice resulted in stable SI-OHT with 6 weeks of application. Intracameral injection of HC-06 resulted in a profound and significant decrease in IOP to that of non-steroid treated animals. Treatment with ML-402 also resulted in a significant reduction in SI-OHT.
Conclusions :
We demonstrated that TRPV4 inhibition and TREK1 activation reduced the cytoskeletal changes, alterations in gene expression, and intraocular pressure associated with chronic steroid exposure. These results provide evidence that targeting either mechanosensitive pathway may provide new potential steroid-induced glaucoma treatment strategies.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.