Advanced glycation end products mediate transforming growth factor-β1 and fibronectin synthesis by mesangial cells cultured under high glucose

다국어 초록 (Multilingual Abstract)

Background: Advanced glycation end products (AGEs) have been implicated in the pathogenesis of diabetic complications including nephropathy. Aminoguanidine prevents formation of AGEs and protein cross linking and has been shown to delay the onset and the progression of glomerular injury in experimental diabetic animals. Long-term exposure of mesangial cells to high glucose significantly increases transforming growth factor (TGF)-β1 and extracellular matrix mRNA and protein expression, which are two prominent features of diabetic glomerulopathy. However, the role of AGEs in mesangial cell activation induced by long-term exposure to high glucose has not been elucidated.
Methods: The effects of aminoguanidine on the synthesis of TGF-β1 and fibronectin by rat mesangial cells cultured under high glucose for 2 weeks were examined and compared with the effects of N^(G)-nitro-L-arginine methyl ester (NAME), a selective nitric oxide synthase inhibitor, because aminoguanidine also inhibits the inducible nitric oxide synthase.
Results: Culture of mesangial cells in 30 mM (high) glucose for 2 weeks induced 1.5-fold (ELISA) and 1.9-fold (Western blot analysis) increase in AGEs in the culture media. Northern blot analysis revealed 1.5-fold increase in TGF-β1 and 1.7-fold increase in fibronectin mRNA expression in cells cultured under high glucose compared to 5.6 mM (control) glucose. Increases in mRNA expression were followed by increased protein synthesis. Mink lung epithelial cell growth inhibition assay revealed 1.4-fold increase in TGF-01 protein in high glucose media compared to control. Fibronectin protein also increased 2.1-fold that of control glucose by Western blot analysis. Administration of aminoguanidine suppressed AGE formation in a dose dependent manner and at the same time suppressed TGF-β1 and fibronectin synthesis by mesangial cells cultured in both control and high glucose. In contrast, NAME did not affect high glucose-induced changes.
Conclusion: These findings support a role for AGEs in high glucose-induced upregulation of TGF-β1 and fibronectin synthesis by mesangial cells.

목차 (Table of Contents)

• Contents
• ABSTRACT
• INTRODUCTION
• METHODS
• Mesangial cell culture
• Northern blot analysis
• ELISA
• Bioassay for TGF-β activity
• Western blot analysis
• Analysis of data
• RESULTS
• DISCUSSION
• ACKN0WLEDGEMENT
• REFERENCES