Otago Glaucoma Surgery Outcome Study: the pattern of expression of MMPs and TIMPs in bleb capsules surrounding Molteno implants

Abstract

Purpose: To determine whether MMPs and TIMPs are present in the bleb wall of Molteno implants.

Methods: An observational case series consisting of ocular specimens from 10 human eyes obtained postmortem from patients who had undergone placement of Molteno implants for glaucoma. Immunohistochemistry was performed on the specimens to determine the distribution of MMP1, -2, and -3 and TIMP1, -2, and -3 in each bleb. The immunohistochemical staining was correlated with the histologic features observed in hematoxylin and eosin (H&E)-stained sections of the bleb wall.

Results: The specimens demonstrated extensive cytoplasmic staining for MMP1, -2, and -3 in fibroblasts within the bleb wall and in degenerating collagen near inner bleb wall fibroblasts undergoing apoptosis. In addition, there was staining for the presence of TIMP2 but not -1 or -3.

Conclusions: MMPs are present in the bleb walls of Molteno implants. TIMP2 is expressed in most bleb capsules. The observations from this study support the hypothesis that bleb capsules undergo a cycle of collagen breakdown and renewal throughout the life of the bleb as members of the MMP family were localized in the bleb wall.