Abstract
Purpose :
Proliferative vitreoretinopathy (PVR) is an abnormal wound healing response following retinal tears. Cellular membranes form on the subretinal and/or epiretinal surface of the retina resulting in scarring, which can be contractile causing retinal detachments and vision loss. The most aggressive forms of PVR derive from retinal pigment epithelial (RPE) cells. The cytokines TGFβ and TNFα have been shown to play a role in PVR. An in vitro model of PVR combined these cytokines (referred to as TNT), inducing contractile membranes in RPE. A p38 inhibitor (Comms Bio 2019; 2: 1-14) and nicotinamide (Stem Cell Rep 2020; 14: 631-647) prevented these aggressive contractile masses in RPE. Additional tests on patient derived PVR membranes would validate the TNT model, confirming the anti-PVR effects of p38 inhibition and nicotinamide.
Methods :
A patient-dissected membrane was divided for immunofluorescence or digestion with collagenase II. The isolated cells were cultured, expanded and assessed for their ability to contract under the TNT conditions of the in vitro PVR model, as well as determine if p38 inhibition and nicotinamide can prevent TNT induced contraction.
Results :
The PVR membrane contained RPE and glia, along with markers for epithelial to mesenchymal transition (EMT), motility and extracellular matrix (ECM). Isolated cells from the patient-dissected PVR membrane may have undergone mesenchymal to epithelial transition (MET), as EMT markers were only present in TNT conditions. TNT induced the cells to undergo EMT forming contractile masses. The p38 inhibitor and nicotinamide prevented contraction, however, EMT was not fully reversed as EMT markers (αSMA and SNAI1) positively labelled cells. Motility and ECM markers were present in all conditions, with TNT treatment having the highest expression. Cells treated with the p38 inhibitor or nicotinamide exhibited decreased motility (ACTG2) and ECM (COL1a2 and Laminin) protein production compared to TNT treatment.
Conclusions :
Both the p38 inhibitor and nicotinamide prevented membrane contraction showing promise to become a therapeutic treatment for patients at risk of developing PVR and individuals with already formed membranes, both treatments warrant further study in an in vivo model of PVR.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.