Relevance of P38 in TGF–B–Induced Human Tenon Myofibroblast Transdifferentiation

Abstract

Abstract: : Purpose: Postoperative filtration bleb failure due to scar formation is still the most prominent problem in fistulating glaucoma surgery. TGF–ß is a pivotal cytokine in this scarring process and specific inhibition of TGF–ß–signalling may therefore offer new treatment options. As our previous experiments had indicated a role of p38 in TGF–ß signalling in human tenon fibroblasts, we investigated the functional significance of p38 in myofibroblast transdifferentiation. Methods: Primary human tenon fibroblast (HTF) cultures were characterized by immunocytochemistry and treated with TGF–ß. The time course of MAPK signalling and the influence of various kinase inhibitors on α smooth muscle actin (αSMA) expression were assessed by Western Blot. On a functional level, the effects of TGF–ß and kinase inhibitors were studied in 3D collagen gel contraction assays by morphometry and confocal laser microscopy. Results: TGF–ß activates p38 in a sustained biphasic manner, while ERK is activated briefly. Different p38–inhibitors diminished TGF–ß–induced αSMA–expression, while the ERK–inhibitor U0216 had no effect. Both, spontaneous and TGF–ß–induced collagen gel contraction were attenuated by p38 inhibitors, but slightly increased by U0216. p38–inhibitors decreased stress fiber formation in collagen–gel embedded HTF. Conclusions: TGF–ß–induced myofibroblast transdifferentiation is structurally and functionally attenuated by p38–inhibitors. Furthermore, intrinsic contraction of HTF–populated collagen gels is diminished by p38–inhibition. These data indicate a significant role of p38 in human tenon myofibroblast transdifferentiation. p38–inhibitors may therefore serve as additional agents to prevent postoperative scarring in glaucoma surgery.

Keywords: wound healing • signal transduction • conjunctiva