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Editors Selection IGR 11-4
Surgical Treatment: Long-lasting effects of MMC
Comment by Douglas Rhee on:
45871 MMP expression in leaking filtering blebs and tears after glaucoma filtering surgery, Mathalone N; Marmor S; Rahat MA et al., Graefe's Archive for Clinical and Experimental Ophthalmology, 2011; 249: 1047-1055
Mathalone et al. (1003) have made an important contribution to our understanding of the long-lasting effects of antimetabolites, specifically mitomycin- C (MMC) in this series, on one of the most important enzyme systems for remodeling of extracellular matrix. Matrix metalloproteinases (MMPs) are proteases that, as a group, are able to degrade all components of the extracellular matrix. Tissue inhibitors of matrix metalloproteinases (TIMPs) are key regulatory proteins for MMPs and are involved primarily as kinetic inhibitors, but are also part of the activation of MMPs from their latent to active forms. Remodeling of the extracellular matrix is critical to the healing of any wound or injury. Understanding the specific wound modulating factors that result in a successful, failed, or leaking conjunctival bleb could lead to more successful outcomes and/or decreased long-term complications.
Interestingly, they found more extensive MMP-2 and MMP-9 activity within the conjunctival tissue compared to controls. Although these findings could be secondary to chronic use of topical medications, it seems to provide evidence that long after a bleb is considered matured or healed, that remodeling continues.
Logically, this is consistent with a slow, but continuous rate of failure of conjunctival blebs over time. Furthermore, the investigators found that expression inhibitors, TIMP-1 and TIMP-2, may be permanently ablated from the stroma of MMC treated conjunctiva.
Long after a bleb is considered matured or healed remodeling continues
They also found changes in the tear film, however, there are other possible confounders affecting the tear film. This group has provided important information and further study is warranted.
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