Expression of gelatinase B in trachomatous conjunctivitis

Background/aims-Gelatinase B is a matrix metalloproteinase involved in extr acellular matrix (ECR) breakdown often associated with scarring and other p athological disorders. It was investigated whether gelatinase B is involved in the pathogenesis of ECM degradation associated with trachomatous conjun ctivitis. Methods-Conjunctival biopsy specimens obtained from six patients with activ e trachoma, six patients with active vernal keratoconjunctivitis (VKC), and seven control subjects were studied. Immunohistochemical techniques and a specific monoclonal antibody against human gelatinase B were used, and a mo noclonal antibody against macrophage CD68 to identify mononuclear cells wit h gelatinase B immunoreactivity. In addition, quantitative zymography was u sed to compare the activity of gelatinase B in conjunctival biopsy specimen s from seven patients with active trachoma and seven control subjects. Results-Gelatinase B was detected by immunohistochemistry only in polymorph onuclear cells located in the vascular lumens in three normal conjunctival biopsy specimens. In all trachoma specimens and in five VKC specimens, gela tinase B was localised in monocyte/macrophage cells, positive for the CD68 marker, and in polymorphonuclear cells. The majority of the latter cell typ e was located in intravascular spaces. Compared with VKC specimens, trachom a specimens showed significantly more immunoreactive gelatinase B monocyte/ macrophage cells (52.3 (21.9) v 8.2 (6.4); p <0.001) and polymorphonuclear cells (23.2 (14.2) v 6.3 (5.4); p = 0.013). Activated macrophages with gia nt cell morphology clearly stained with the gelatinase B specific monoclona l antibody were observed in trachoma specimens. Zymography revealed that ge latinase B levels in trachoma specimens were significantly higher than the levels found in normal conjunctiva (1739.6 (1078.3) v 609.3 (395.9) scannin g units; p = 0.0127). Conclusions-The increased activity of gelatinase B and numbers of inflammat ory cells containing gelatinase B in trachoma specimens suggest that this e nzyme plays a part in the pathogenesis of conjunctival scarring in trachoma .