Factors associated with changes in endothelin-1 gene expression in patients with diabetic retinopathy in type 2 diabetes mellitus

PURPOSE: To (i) investigate expression of the endothelin-1 (ET-1) gene in peripheral blood mononuclear cells (PBMCs) of patients with type 2 diabetes mellitus (DM) and (ii) determine what correlations, if any, exist between expression of ET-1 in patients with type 2 DM and treatment, clinical features, and biochemical markers in diabetic retinopathy (DR). METHODS: The study group included 58 patients with type 2 DM, subdivided into three subgroups: those without DR (n=19), those with nonproliferative DR (NPDR; n=28), and those with proliferative DR (PDR; n=11). The control group consisted of 60 individuals. In all groups the mRNA level of ET-1 was estimated using real-time quantitative reverse transcription PCR. RESULTS: The mRNA level of ET-1 in patients with NPDR was significantly higher than in those without DR. An increase in ET-1 expression was observed in patients with PDR as opposed to those without DR. Compared to controls, the mRNA level of ET-1 was significantly higher both in patients with NPDR and those with PDR. Duration of DM, insulin therapy, and serum creatinine levels were associated with increased mRNA level of ET-1, whereas medication with sulfonylurea or angiotensin-converting enzyme inhibitors had the opposite effect. CONCLUSIONS: Expression of ET-1 in PBMCs may be associated with severity of DR in patients with type 2 DM. Long-standing clinical course of DR; medication with insulin, sulfonylurea, or ACE inhibitors; and serum creatinine levels are factors possibly associated with changes in ET-1 expression in PBMCs.