Abstract
Abstract: :
Purpose: To study the mRNA localization of membrane-type matrix metalloproteinases (MT-MMPs) and the expression of MMP-2 and tissue inhibitor of metalloproteinase 2 (TIMP-2) in infected mouse corneas. Methods: C57BL/6J mice were intracorneally infected with Pseudomonas aeruginosa. Corneal samples were collected at different time points after the infection and subjected to in situ hybridization, RT-PCR, ELISA, and gelatin zymography. Results: Only very weak signals for MT-MMP transcripts were found in normal corneas. With P. aeruginosa infection, strong signals were detected in corneal tissues. Among them, MT1-MMP transcript was localized predominantly in epithelial tissues whereas MT2- and MT-3 MMP transcripts were in the stroma adjacent to epithelial tissues. Although there was no significant difference in MMP-2 mRNA expression between normal and infected corneas, gelatin zymography showed induction of both latent and active MMP-2 in infected corneas compared to that in normal corneas. TIMP-2, a major endogenous inhibitor of MMP-2 and also an essential factor for pro-MMP-2 activation, was detected at both the transcript and protein levels in normal corneas. However, its expression was slightly suppressed during the early stage of infection but gradually recovered and then was induced during the late stage of infection. Conclusion: Localization of MT1-, MT2- and MT3-MMP transcripts revealed different distributions of MT-MMPs in infected corneas, which is consistent with our previous findings at the protein level using immunohistochemical staining. With induced MT-MMP expression and certain levels of TIMP-2 in infected corneas, MMP-2 expression and activation occurred, which could play a role in corneal destruction during P. aeruginosa infection.
Keywords: 399 enzymes/enzyme inhibitors • 437 inflammation • 370 cornea: basic science