Sphingosine-1-phosphate expression in human epiretinal membranes

The abnormal posterior vitreous detachment (PVD) is speculated as an important mechanism of the development of the epiretinal membrane (ERM). However, there is only limited information about the molecular mechanism. Sphingosine-1-phosphate (S1P) is a mediator of the mechanosensitive response in several cell types that may have a role in the pathogenesis of ERM during abnormal PVD. Therefore, we evaluated the expression of S1P in the human ERM and the role of S1P in cultured human Muller glial cells. Among 24 ERM specimens, seven specimens (29.2%) exhibited S1P expression. Patients with secondary ERM or ellipsoid zone defects, which suggest abnormal PVD presented a significantly higher S1P + cell density (secondary ERM: 128.20 +/- 135.61 and 9.68 +/- 36.01 cells, p= 0.002; EZ defects: 87.56 +/- 117.79 vs 2.80 +/- 8.85, p= 0.036). The addition of S1P increased the migrative ability and expression of N-cadherin and alpha-SMA in human Muller glial cells, suggesting S1P is a potential causative molecule for the development of ERM during abnormal PVD.