MMP9 and osteomyelitis: Matrix metalloproteinase 9 (MMP9), which also belongs to the matrix metalloproteinase family, has gelatinase activity that degrades extracellular matrix and basement membrane components, with detrimental effects on endothelial integrity and collagen fibers.[36] Gene expression levels of MMP9 are significantly higher in osteomyelitis than in normal subjects.[37] The NF-κB signaling pathway is involved in the common pathogenesis of osteomyelitis and DFU, and MMP9 is related to pro-inflammatory cytokines and osteoclast-associated genes.