MMP9 and infection: In recent years, majority of in vivo Mtb investigations have been carried out by using mouse model, and different mouse strains and different infection methods have been created.123Mtb infection has been reported to upregulate MMP‐9 expression in Mtb‐infected mouse.124 In another study, MMP‐9 knockout mice exhibited reduced cellular recruitment to the lung granuloma.125 These studies implicate that MMP‐9 is required for recruitment of macrophages and tissue remodelling in Mtb infection of mice.