The Nephroprotective Effect of TNF Receptor-Associated Factor 6 (TRAF6) Blockade on LPS-Induced Acute Renal Injury Through the Inhibition if Inflammation and Oxidative Stress.

ABSTRACT

BACKGROUND Inflammation and oxidative stress play important roles in the pathogenesis of acute kidney injury (AKI). TRAF6 functions as a signal transducer in the Toll-like receptor 4 signaling pathway. Several reports have previously implicated TRAF6 signaling in kidney pathology. Here, we investigated whether TRAF6 blockade can mitigate inflammatory responses and oxidative stress in AKI. MATERIAL AND METHODS C57BL/6 mice were injected with lipopolysaccharide (LPS, 15 mg/kg) to induce AKI. Double immunofluorescence staining of kidney tissues showed that TRAF6 was localized to renal tubular epithelial cells, and then a tubular epithelial cell line (NRK-52E) was used for in vitro analysis. TRAF6 was blocked in vitro using siRNA and in vivo using AAV2/2 shRNA. RESULTS The knockdown of TRAF6 in mice by AAV2-shTRAF6 significantly reduced renal inflammation, oxidative stress, apoptosis and kidney dysfunction in AKI. In vitro, silencing the expression of TRAF6 attenuated LPS(0.5 µg/mL)-induced inflammatory responses and oxidative stress and upregulated proapoptotic factors. Furthermore, the beneficial actions of TRAF6 blockade were closely associated with its ability to increase IkappaB-alpha and Nrf2. CONCLUSIONS Our findings provide direct evidence that TRAF6 mediates LPS-induced inflammation and oxidative stress, leading to renal dysfunction. We also show that TRAF6 inhibition is a potential therapeutic option to prevent AKI.