MMP9 and inclusion conjunctivitis: Immunohistochemistry (IHC) studies using tissue from a small number of individuals with active trachoma have shown that MMP9, CTGF, platelet derived growth factor (PDGF) and IL-1β were up-regulated in infiltrating monocytes/macrophages and that IL-1β was increased in the conjunctival epithelium [10–12].