Sleeve gastrectomy links the attenuation of diabetic kidney disease to the inhibition of renal tubular ferroptosis through down-regulating TGF-β1/Smad3 signaling pathway

Purpose To investigate how sleeve gastrectomy (SG), a typical operation of bariatric surgery, attenuated symptom, and progression of diabetic kidney disease (DKD). Methods DKD model was induced by high-fat diet (HFD) combined with streptozocin in Wistar rats. SG was performed, and the group subjected to sham surgery served as control. The animals were euthanized 12 weeks after surgery, followed by sample collection for the subsequent experiment. The HK-2, a renal proximal tubular epithelial cell line derived from human, was utilized to investigate the potential mechanisms. Results SG improved metabolic parameters and glucose homeostasis, and could alleviate DKD in terms of renal function indices as well as histological and morphological structures in DM rats, accompanied with a significant reduction in renal tubular injury. Compared with sham group, SG reduced the renal tubular ferroptosis. To further clarify the mechanism involved, in vitro experiments were performed. In the presence of high glucose, renal tubular TGF-beta 1 secretion was significantly increased in HK-2 cell line, which led to activation of ferroptosis through TGF-beta 1/Smad3 signaling pathway. Inhibition of TGF-beta 1 receptor and phosphorylation of Smad3 significantly ameliorated TGF-beta 1-mediated ferroptosis. In vivo experiments also found that SG improved the hyperglycemic environment, reduced renal TGF-beta 1 concentrations, and down-regulated the TGF-beta 1/Smad3 signaling pathway. Conclusions With the capacity to lower the glucose, SG could attenuate the ferroptosis by inhibiting TGF-beta 1/Smad3 signaling pathway in DKD rats, and eventually attenuated DKD.