Expression of autotaxin and acylglycerol kinase in proliferative vitreoretinal epiretinal membranes

Abstract

Lysophosphatidic acid (LPA)/LPA(1) receptor pathway is involved in inflammation, angiogenesis and fibrosis. This study was conducted to analyse the expression of LPA-producing enzymes, autotaxin (ATX) and acylglycerol kinase (AGK) and LPA(1) receptor, in proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR) epiretinal membranes. Nine active and 13 inactive membranes from patients with PDR and 21 membranes from patients with PVR were studied by immunohistochemistry. In PDR membranes, vascular endothelial cells expressed ATX and AGK in 16 and 19 membranes, respectively. Stromal cells expressed ATX and AGK in 19 and 22 membranes, respectively. Immunoreactivity for LPA(1) receptor was noted in vascular endothelial cells and stromal cells in the five membranes stained for LPA(1) receptor. Numbers of blood vessels and stromal cells expressing CD34, ATX and AGK were significantly higher in active membranes than in inactive membranes. Significant correlations were detected between number of blood vessels expressing the panendothelial cell marker CD34 and number of blood vessels and stromal cells expressing ATX and AGK. In PVR membranes, spindle-shaped myofibroblasts expressing α-smooth muscle actin co-expressed ATX, AGK and LPA(1) receptor. The LPA/LPA(1) receptor pathway may be involved in inflammatory, angiogenic and fibrotic responses in proliferative vitreoretinal disorders.