387-P: Novel Mitochondrial Complex I Modulator Reduces Diabetes-Associated Expression of Inflammation and Fibrosis Markers in Human Proximal Tubular Epithelial Cells

Diabetic kidney disease (DKD) is a chronic microvascular complication of diabetes and accounts for 30-40% of all diabetic patients. Patients with DKD experience a progressive and irreversible decline of renal function until dialysis and kidney transplantation become the last line of intervention. Renal loss of function is driven by the diabetic milieu causing an imbalance between the generation of reactive oxygen species (ROS) and the antioxidant defense mechanisms. The excessive amounts of ROS, driven either by mitochondria or by NADPH oxidases (NOXs) , cause inflammation and eventually lead to fibrosis and kidney failure. Methods: To address this problem, we cultivated healthy primary human renal cells (renal proximal tubular epithelial cells) under diabetic conditions. The cells were treated either with 5mM normal glucose (NG) , or 25mM high glucose with 10ng/ml TNF-α or TGF-β (HG) for 24h. In addition, a novel mitochondrial complex I modulator (BIM, 250nM) that has been designed to interfere with the ROS production at mitochondrial complex I has been tested in combination with the treatments. We analyzed the gene expression of different oxidative stress, inflammation as well as fibrosis markers. Results: On the transcriptional level, a treatment with BIM resulted in a significant downregulation of the HG treatment-induced expression of the oxidative stress markers SOD2 (by 40%) , NOX4 (by 61%) and NOX5 (by 34%) , the inflammation markers IL1B (by 29%) and TNFA (by 22%) , as well as the fibrosis markers TGFB1 (by 23%) , COL4A1 (by 50%) and CTGF (by 43%) , as determined by a two-way ANOVA and Tukey’s multiple comparison. Conclusion: The reduction of these markers after treatment with the complex I modulator suggests renoprotective properties in vitro. Further in vivo experiments in diabetic db/db mice will reveal whether the novel mitochondrial complex I modulator can attenuate renal injury in DKD.