Multifaceted renoprotection by SMTP-44D in diabetic nephropathy: Targeting inflammation, oxidative stress, and insulin resistance.

Abstract

Diabetic nephropathy (DN) is a major complication of diabetes and a leading cause of dialysis initiation. However, treatment options for DN are currently limited, highlighting the urgent need for novel therapies. The pathogenesis of DN involves persistent chronic hyperglycemia and advanced glycation end products, leading to inflammation, and oxidative stress. SMTP-44D, a compound derived from Stachybotrys microspora, exhibits anti-inflammatory and antioxidant properties. This study aimed to elucidate the renoprotective mechanism of SMTP-44D in DN. To establish a DN model, 6-week-old db/db mice underwent unilateral nephrectomy, and the model animals were treated with SMTP-44D for 10 weeks. Key physiological parameters, blood glucose levels, soluble epoxide hydrolase (sEH) substrates [epoxyeicosatrienoic acids (EETs) and lysophosphatidic acids (LPAs)], and the critical signaling molecule nuclear factor-kappa B (NF-κB) and Peroxisome Proliferator-Activated Receptor Gamma (PPARγ), were analyzed. Our results demonstrated that SMTP-44D increased the levels of serum EETs and LPAs in DN model animals. Following SMTP-44D treatment, the fraction of nuclear NF-κB decreased and cytoplasmic PPARγ level increased in the renal tissues. These results are consistent with the hypothesis that SMTP-44D inhibits sEH, causing an accumulation of substrates that act as signaling molecules controlling inflammatory processes via NF-κB. Furthermore, SMTP-44D improved insulin resistance, as evidenced by reduced blood glucose levels. In conclusion, SMTP-44D represents a promising novel therapeutic candidate for DN, offering a multifaceted approach that addresses inflammation, oxidative stress, and insulin resistance.