IMMUNOREACTIVE ENDOTHELIN-1 IN THE VITREOUS HUMOR AND EPIRETINAL MEMBRANES OF PATIENTS WITH PROLIFERATIVE DIABETIC RETINOPATHY

Abstract

In Brief Purpose: To investigate the potential role of endothelin-1 (ET-1), a potent vasoconstrictor with mitogenic properties, in the pathogenesis of proliferative diabetic retinopathy (PDR). Methods: Plasma and vitreous samples were collected from normal patients (controls; n = 25), diabetic patients with PDR (n = 25), and diabetic patients with non-PDR (n = 25). The patients had to have epiretinal membranes (ERMs) or other ocular conditions that made them candidates for vitrectomy. Immunoreactive ET-1 (IR-ET-1) was assayed in plasma and vitreous samples by radioimmunoassay. IR-ET-1 was immunohistochemically localized in ERMs. Expression of endothelin receptors A (ETA) and B (ETB) was confirmed by reverse transcription–polymerase chain reaction analysis. Results: IR-ET-1 levels in plasma and vitreous samples from diabetic patients were higher (P < 0.0001) than those in samples from the control group. The levels for patients with PDR were even higher (P < 0.0001) than those for patients with non-PDR. Eyes with ERMs in the PDR group had the highest vitreous IR-ET-1 levels (14.67 ± 0.67 pg/mL). IR-ET-1 was localized in the cellular and stromal components of ERMs in diabetic and nondiabetic patients. Furthermore, the ETA and ETB receptors were expressed in both diabetic and nondiabetic ERMs. Conclusions: Diabetic patients with PDR and ERMs had the highest plasma and vitreous IR-ET-1 levels. ET-1 and its ETA and ETB receptors were present in ERMs. These data suggest that ET-1 is involved in diabetic vitreoretinal disease. IR-ET-1 levels in plasma and vitreous in patients with proliferative diabetic retinopathy (PDR) were higher (p < 0.0001) than in those with non-PDR. Eyes with epiretinal membranes (ERMs) from the PDR patient group showed the highest vitreous IR-ET-1 levels (14,67 ± 0,67 pg/ml). In addition to that, ET-1 and its receptors (ETA and ETB) are present in ERMs.