Insights into the regulation of glomerular filtration rate by the Keap1-Nrf2 pathway.

BACKGROUND: Literature data suggest that the activation of the Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway increases glomerular filtration rate (GFR) in patients with type 2 diabetes and chronic kidney disease. However, the mechanisms whereby the Keap1-Nrf2 pathway regulates GFR are unknown. Methods: Various renal physiological parameters were assessed in C57BL/6 mice (WT), Nrf2-deficient mice, and Nrf2-activated Keap1-knockdown mice. Also, these parameters were assessed following the administration of RTA dh404 (CDDO-dhTFEA), a Nrf2 activator.

RESULTS: Pharmacological and genetic Keap1-Nrf2 activation increased renal blood flow (p <0.05), glomerular volume (p <0.05) and GFR (p <0.05), but did not alter the afferent-to-efferent arteriolar diameter ratio or glomerular permeability. Calcium influx into the podocytes through TRPC channels in response to H2O2 was suppressed by Keap1-Nrf2 activation and TRPCs inhibition. Treatment with a TRPC6 and TRPC5 inhibitors increased single-nephron GFR in WT mice.

CONCLUSION: In conclusion, the Keap1-Nrf2 pathway regulates GFR through changes in ultrafiltration by modulating redox-sensitive intracellular calcium signaling and cellular contractility, mediated through TRPC activity, in glomerular cells, in particular the podocytes.