MMP9 and infection: Necropsy of brains from lethal infections revealed exponential increases in expression of traumatic brain injury genes [leukemia inhibitory factor (LIF), matrix metalloproteinase-9 (MMP-9)] as well as inflammatory cytokines and chemokines [IFNγ, CXCL10, monocyte chemoattractant protein-1 (MCP-1), interleukin 8 (IL-8), IL-6] [49], which implies that altered host cell signaling contributes to fatal outcomes.