Expression of myofibroblast activation molecules in proliferative vitreoretinopathy epiretinal membranes

Purpose: Fibrotic disorders are associated with activation of fibroblasts into extracellular matrix‐secreting myofibroblasts expressing α‐smooth muscle actin (α‐SMA). Myofibroblasts are the predominant cellular component of proliferative vitreoretinopathy (PVR) epiretinal membranes. We investigated the expression of molecules involved in myofibroblast activation, migration and proliferation in PVR epiretinal membranes. Methods: Fifteen membranes were studied by immunohistochemical techniques using monoclonal and polyclonal antibodies directed against snail, fibroblast activation protein (FAP), CD44, hydrogen peroxide‐inducible clone‐5 (Hic‐5), galectin‐3, interleukin‐13 receptor α2 (IL‐13Rα2) and receptor for advanced glycation end products (RAGE). Results: Myofibroblasts expressing α‐SMA were present in all membranes. Myofibroblasts expressed nuclear immunoreactivity for Snail and Hic‐5, cytoplasmic immunoreactivity for FAP, IL‐13Rα2 and RAGE and membranous immunoreactivity for CD44. There was no immunoreactivity for galectin‐3. The number of cells expressing α‐SMA correlated significantly with the number of cells expressing Snail (r = 0.56; p = 0.03), Hic‐5 (r = 0.526; p = 0.044), IL‐13Rα2 (r = 0.773; p = 0.001) and RAGE (r = 0.734; p = 0.002). Conclusions: Snail, FAP, CD44, Hic‐5, IL13Rα2 and RAGE may be involved in proliferative events occurring in PVR.