Jiangtang Tiaozhi formula improves obesity and insulin resistance by inhibiting skeletal muscle inflammation and pyroptosis in diet-induced obese mice

BACKGROUND: The global prevalence of obesity continues to rise annually. Jiangtang Tiaozhi (JTTZ) formula, a traditional Chinese medicine formula, is clinically utilized for treating obesity and type 2 diabetes due to its therapeutic efficacy. However, the underlying mechanisms of JTTZ formula for improving obesity and insulin resistance (IR) remain unclear. PURPOSE: This study aimed to elucidate the mechanistic basis of JTTZ formula's anti-obesity effects, specifically evaluating its role in ameliorating IR and reducing body weight. METHODS: High-fat diet (HFD)- and high-fat and high-sucrose diet (HFHSD)-induced obese (DIO) mice were assessed for determining the effects of JTTZ formula on body weights, IR, serum lipid profiles, and inflammatory markers in the serum and gastrocnemius muscle. Transcriptomic analysis of the gastrocnemius tissues of HFD-fed mice was performed, followed by RT-qPCR analysis and immunofluorescence staining to evaluate the changes of inflammation- and pyroptosis-related genes/proteins. Molecular docking and surface plasmon resonance assays were used to assess the binding affinity of 12 blood components derived from JTTZ formula to the pyroptosis-associated protein, NLRP3. In addition, the influences of JTTZ formula and its bioactive compounds on cell viability, lipid accumulation, inflammatory cytokine release, and pyroptosis were determined in the palmitic acid (PA)-induced C2C12 and L6 myotubes model of IR. RESULTS: JTTZ formula significantly reduced the body weight, adiposity, and improved IR of HFD- and HFHSD-induced DIO mice while improving gastrocnemius muscle morphology and suppressing systemic and muscular inflammation. Transcriptomics and molecular assays revealed that JTTZ formula could regulate the tumor necrosis factor, NOD-like receptor, and nuclear factor kappa B signaling pathways to inhibit inflammation and pyroptosis for the improvement of IR in muscles. Among the various components of JTTZ formula, cryptotanshinone, diosgenin, and timosaponin A1 exhibited significant NLRP3-binding affinity. The active constituents of JTTZ formula including berberine, cryptotanshinone, neomangiferin, and palmatine attenuated PA-induced IR, lipid deposition, inflammation, and pyroptosis in C2C12 and L6 myotubes. CONCLUSION: JTTZ formula could ameliorate obesity-associated metabolic dysfunction and improve IR by enhancing glucose uptake, reducing lipid accumulation in skeletal muscles. Its effects were mediated by attenuating inflammation and pyroptosis in muscle tissues. Berberine, cryptotanshinone, neomangiferin, and palmatine might be the bioactive components of JTTZ formula against obesity-related IR.