Angiotensin-converting enzyme inhibition modulates high-glucose-induced extracellular matrix changes in mouse glomerular epithelial cells.

Background/aim: Extracellular matrix alterations are involved in the pathogenesis of diabetic nephropathy. We evaluated the effects of high glucose concentrations and inhibition of angiotensin-converting enzyme on the laminin and fibronectin production by glomerular epithelial cells.

Methods: Glomerular epithelial cells were cultured in 5 and 30 mmol/l glucose, with and without enalaprilat (0.3 mmol/l). Laminin and fibronectin were measured (35S-methionine, immunoprecipitation), and their mRNA expression was evaluated (RT-PCR).

Results: The laminin concentration was higher in the cells than in the medium, where an increase of its content was observed under high-glucose conditions (p < 0.01). Fibronectin, found only in the medium, was not modified by the high glucose concentration. Following enalaprilat administration, the laminin concentration was decreased under high-glucose conditions, both in the cell and in the medium (p < 0.001), whereas the fibronectin concentration was increased under high-glucose conditions (p < 0.001). The mRNA expression of laminin and fibronectin under high-glucose conditions only slightly increased. Enalaprilat decreased the fibronectin mRNA synthesis dramatically (>50%, p < 0.0001) under high-glucose conditions.

Conclusions: Enalaprilat normalizes the abnormal, high-glucose-induced concentration of laminin, while it decreases the fibronectin synthesis. The improvement of the renal function in diabetic patients treated with angiotensin-converting enzyme inhibitors may, in part, be due to a modulator effect on extracellular matrix content and composition.