Abstract
Purpose :
Retinal pigment epithelial (RPE) cells contribute to several clinical conditions resulting in retinal fibrotic scars. Upon exposure to TGF-β, a key fibrotic cytokine, RPE cells trans-differentiate to myofibroblasts marked by the integration of α-SMA fibers into F-actin stress fibers which confers strong contractility. Myofibroblasts produce and contract the collagen-rich fibrotic scar and disrupt retinal architecture. In this study, we investigated the effects of a putative endocannabinoid compound N-oleoyl dopamine (OLDA) on TGF-β2 induced porcine RPE cell contraction and α-SMA expression in vitro.
Methods :
Porcine RPE cells were isolated and the collagen matrix contraction assay was used to assess myofibroblast function. Briefly, RPE cells (10x10^4) were plated on solidified collagen in a 24-well plate and treated with OLDA and TGF-β2 (10 ng/mL) for 72 hours. Collagen gels were released from the well, allowed to contract for 4 hours, and photographed for analysis. Collagen gels with attached cells were subsequently used for western blot analysis. For immunocytochemistry, collagen gels with cells attached were not released from the well, but rather fixed and stained for α-SMA, F-actin, and DAPI. Lastly, a bromodeoxyuridine (BrdU) incorporation assay was used to assess proliferation.
Results :
Using an in vitro collagen matrix contraction assay, we found that OLDA inhibited TGF-β2 induced contraction of collagen matrices by porcine RPE cells. This effect was concentration-dependent, with significant inhibition of contraction at 3 μM and 10 μM. OLDA did not significantly affect the proliferation of porcine RPE cells. Immunocytochemistry showed that at 3 μM and 10 μM.OLDA significantly decreased expression of α-SMA fibers in stress fibers of the TGF-β2 induced porcine RPE cells. In addition, western blot analysis demonstrated that OLDA downregulated TGF-β2 induced α-SMA protein expression.
Conclusions :
Taken together these results indicate that OLDA inhbits myofibroblast trans-differentiaion of RPE Cells and has potential to inhibit TGF-β induced fibrosis in the retina. Further studies are warranted to investigate the mechanism of action, other fibrotic end points, as well as the potential therapeutic effects of OLDA in animal models of retinal fibrosis.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.