Among them, MMP-9 can degrade almost all extracellular matrix components such as collagen fibers, elastic fibers, and proteoglycans in the alveolar wall, induce the migration of polynuclear granulocytes, and change their morphology, thereby improving the permeability of microvessels and promoting the migration of polynuclear granulocytes., causing organ damage and the spread of inflammation, leading to systemic inflammatory response syndrome, and initiating the cascade of inflammatory response [18]. The gene discussed is MMP9; the disease is systemic inflammatory response syndrome.