The Glucagon-Like Peptide-1 (GLP-1) Receptor Agonist Liraglutide Regulates Sirtuin-1-Mediated Neutrophil Extracellular Traps to Improve Diabetes-Induced Bone Metabolism Imbalance

Background: Diabetes mellitus (DM) is a chronic metabolic disorder that disrupts normal bone remodeling. Objectives: This study aimed to investigate how the glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide (LIR) addresses bone metabolism imbalances induced by type-II diabetes. Methods: Type-II diabetic rat models were established through a single intraperitoneal injection of streptozotocin (STZ). Blood glucose levels were measured using a blood glucose meter, and insulin levels were assessed using an assay kit. Bone formation markers [alkaline phosphatase (ALP), osteocalcin (OCN), and procollagen I N-terminal propeptide (PINP)] and bone resorption markers [tartrate-resistant acid phosphatase (TRACP) and CTX-1] were monitored using assay kits. Bone marrow mesenchymal stem cells (BMSCs) were cultured in vitro under high-fat and high-glucose (HFHS) conditions to mimic diabetic bone metabolism dysregulation. Neutrophil extracellular traps (NETs) formation was examined through immunofluorescent staining and Western blot analysis. Results: Liraglutide was found to reduce STZ-induced NETs formation, as indicated by decreased expression of cit-H3 by 36.90% - 53.57%, myeloperoxidase (MPO) by 55.81% - 65.12%, NE by 53.95% - 65.17%, and PAD4 by 46.81% - 63.83%, alongside increased Sirtuin-1 (SIRT1) expression in femur tissue (70.71% - 91.19%). In vitro, LIR enhanced osteogenesis and inhibited apoptosis, effects that were partially reversed by SIRT1 knockdown. Additionally, SIRT1 knockdown partially restored LIR-induced reductions in oxidative stress, inflammation, and NETs formation. Conclusions: LIR mitigates diabetes-induced bone metabolism imbalance by inhibiting NETs formation through SIRT1 mediation.