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Nick Di Girolamo, Denis Wakefield, Minas T. Coroneo; Differential Expression of Matrix Metalloproteinases and Their Tissue Inhibitors at the Advancing Pterygium Head. Invest. Ophthalmol. Vis. Sci. 2000;41(13):4142-4149.
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purpose. Pterygia are a proliferative and inflammatory growth of limbal
epithelial stem cell origin, characterized by corneal tissue invasion
and extensive matrix remodeling including the destruction of Bowman’s
layer (BL). The purpose of this study was to determine the expression
of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs
(TIMPs) at the advancing pterygium edge.
methods. Formalin-fixed, paraffin-embedded whole eyes (n = 11)
with pterygia attached, were serially sectioned and analyzed
immunohistochemically to determine the spatial distribution of four
MMPs and three TIMPs. Tear samples were collected from other patients
with pterygia (n = 11) and displayed by gelatin
results. Collagenase-1 was expressed by pterygium epithelial cells, corneal
stromal fibroblasts and pterygium fibroblasts that had migrated between
the epithelium and BL at the advancing pterygium edge. Collagenase-3
and gelatinases A and B were detected in all pterygia, intensely
staining columnar epithelial cells directly adjacent to the denatured
BL. In addition, gelatinase A immunoreactivity was observed on BL.
Immunoreactivity for TIMP-1 and -3 paralleled that of the gelatinases,
with more intense staining in epithelial cells and fibroblasts where BL
was absent. TIMP-2 was faintly detected in pterygium epithelial cells
but intensely stained pterygium fibroblasts. Gelatinase B was the most
abundant gelatinolytic enzyme present in tears, elevated approximately
twofold in eyes with pterygia versus the contralateral control eyes.
conclusions. This investigation is the first to identify the expression pattern of
MMPs and TIMPs at the advancing pterygium edge in specimens of human
eyes and in tears derived from patients with pterygia. These enzymes
may be responsible for the destruction of BL, and their pattern of
differential expression suggests that each may play a selective role in
the pathogenesis of pterygia.
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