TLR-2/4 inhibition accelerates bone repair via modulating MyD88/NF-κB signaling and inflammatory microenvironment.

Fracture healing is a complex process intimately linked to inflammatory responses. Toll-like receptor 2 (TLR-2) and Toll-like receptor 4 (TLR-4) impede fracture healing via the myeloid differentiation primary response gene 88/nuclear factor kappa-B (MyD88/NF-κB) signaling axis, which drives key inflammatory pathways. This study aimed to elucidate whether TLR-2/4 modulates fracture healing via regulation of the MyD88/NF-κB signaling axis. Fracture models were established in Sprague-Dawley (SD) rats and intervened with the TLR-2 inhibitor C29 or the TLR-4 inhibitor TAK-242. The fracture healing process was assessed by behavioral analysis and histopathological evaluation at multiple time points. Bone tissue samples were analyzed for MyD88/NF-κB pathway activity and expression of associated inflammatory (interleukin-1α [IL-1α], interleukin-6 [IL-6], tumor necrosis factor-α [TNF-α]) and bone regeneration factors (runt-related transcription factor 2 [RUNX2], receptor activator of nuclear factor-κB ligand [RANKL], type 1 collagen [Collagen-I], β-catenin). Behavioral and histopathological analyses confirmed that C29 and TAK-242 significantly improved fracture outcomes in rats.TLR-2/4 inhibition effectively suppressed activation of the MyD88/NF-κB pathway and reduced expression of inflammatory factors, while enhancing osteogenic regeneration. These time-dependent effects significantly accelerated late-phase (>14d) fracture repair versus early stages (0-14d), improving bone healing parameters. Targeting TLR-2/4 accelerates fracture repair by suppressing MyD88/NF-κB-driven inflammation and optimizing the bone healing microenvironment.