Roux-en-Y gastric bypass alleviates kidney inflammation and improves kidney function in db/db mice by activating TLCA/TGR5 pathway

Diabetic kidney disease (DKD) is a severe diabetic microvascular complication featured by chronic low-grade inflammation. Roux-en-Y gastric bypass (RYGB) surgery has gained importance as a safe and effective surgery to treat DKD. Bile acids are significantly changed after RYGB, which brings a series of metabolic benefits, but the relationship with the improvement of DKD is unclear. Therefore, this study performed RYGB surgery on db/db mice to observe the beneficial effects of the surgery on the kidneys, and performed bile acid targeted metabolomics analysis to explore bile acid changes. We found that RYGB significantly reduced albuminuria in db/db mice, improved renal function, reversed renal structural lesions, and attenuated podocyte injury, inflammation. Notably, bile acid metabolomic analysis revealed taurolithocholic acid (TLCA) as the most significantly altered bile acid after RYGB. Further in vitro and in vivo validation experiments revealed that TLCA supplementation improved renal function and reduced renal inflammatory damage in db/db mice. In addition, TLCA inhibited high glucose-induced inflammatory damage in MPC-5 cells, and its mechanism of action may be related to activating Takeda G protein-coupled receptor 5 (TGR5), inhibiting NF-κB phosphorylation, and thus inhibiting inflammatory response. In conclusion, RYGB may play a protective role in the kidneys of diabetic mice by activating the TLCA/TGR5 pathway.