MMP9 and bacterial infectious disease: Moreover, MMP-9 is up-regulated in the skin tissue of diabetic wounds with bacterial infection compared with nondiabetic patients with wounds, while that of TIMP-1 as well as VEGF is down-regulated, which indicate that an excessively high ratio of MMP-9/TIMP-1 contributes to delayed wound healing in infected DFUs through reducing VEGF levels (80).