MMP9 and tuberculosis: Like other tissues of the body, inflammation of central nervous system (CNS) also results in increased MMP secretion and it can also affect the permeability of blood brain barrier (BBB).49, 50 Increased expression of MMP‐1 and MMP‐3 has been reported in the patients with TB of CNS.30, 51 Similarly, in a recent study, MMP‐9 upregulation has been noticed in the brain biopsies of the patients having TB meningitis.52 This enhanced activity of MMP‐9 in the brain tissues may be involved in the damage of BBB, oedema and the inflammatory cell exudation.