MMP9 and chronic cystitis: In different studies in which cystitis images were evaluated, the participation of resident macrophages in the bladder that release TNF-α and induce the expression of chemokine [C-X-C motif] ligand 2 (CXCL2) was observed, as well as the activation of neutrophils that stimulates the expression of matrix metalloproteinase-9, which increases its capacity to cross the epithelium favorably modifying cystitis problems [56,57].