Purpose: Endothelin one (ET-1) is a vasomodulator peptide that plays a role on ocular blood flow, glial proliferation, and collagen matrix contraction by retinal pigmented epithelial (RPE) cells. Both glial and RPE cells have been involved in the formation of epiretinal membranes (ERMs). This investigation was conducted to determine whether ET-1 may be associated with ERMs, either idiopathic (IERMs) or from proliferative vitreoretinopathy (PVR).
Methods: Plasma and vitreous samples were collected from patients classified by the presence of PVR membranes, retinal detachment (RD), and other ocular conditions, such as IERMs, that made the patients candidates for vitrectomy. Immunoreactive endothelin one (IR-ET-1) was tested in plasma and vitreous by radioimmunoassay. Immunoreactive-ET-1 was localized in IERMs and PVR membranes immunohistochemically. Expression of endothelin receptors A (ETA) and B (ETB) was confirmed by reverse transcription-polymerase chain reaction.
Results: IR-ET-1 levels in plasma and vitreous were higher in patients with PVR and in patients with RD than in those of the control group. Eyes with IERMs also showed higher IR-ET-1 levels than the control group cases. IR-ET-1 levels in eyes with PVR were higher than those in eyes with IERMs. IR-ET-1 levels in eyes with RD were also higher than those of eyes with IERMs. Immunoreactive ET-1 was localized in the cellular and stromal components of both IERMs and PVR membranes. Furthermore, ETA and ETB receptors were expressed in both IERMs and PVR membranes.
Conclusions: IR-ET-1 in human vitreous is elevated in PVR, RD, and IERMs. ET-1 and its receptors ETA and ETB are present in epiretinal tissue of both idiopathic and PVR membranes. These data suggest an involvement of ET-1 in retinal disease.