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October 1995

Collagen Metabolism in Human Aqueous Humor From Primary Open-angle Glaucoma: Decreased Degradation and Increased Biosynthesis Play a Role in Its Pathogenesis

Author Affiliations

From the Department of Molecular Biology, Instituto Nacional de Enfermedades Respiratorias (Drs González-Avila, Terán, and Selman), "20 de Noviembre," National Medical Center, Biomedical Research and Science Building, ISSSTE (Drs González-Avila and Terán), Instituto de Oftalmologia "Fundación Conde de Valenciana" (Dr Ginebra), and the Department of Biochemistry, Instituto Nacional de Perinatologia (Dr Vadillo-Ortega), México City, México; and the Department of Biochemistry, School of Dentistry, Aichi Gakuin University, Nagoya, Japan (Dr Hayakawa).

Arch Ophthalmol. 1995;113(10):1319-1323. doi:10.1001/archopht.1995.01100100107039

Objective:  To explore the influence of aqueous humor from patients with glaucoma on collagen turnover.

Methods:  The aqueous humor of patients with primary open-angle glaucoma (POAG), chronic angleclosure glaucoma, congenital glaucoma, neovascular glaucoma, and senile cataract (control group) was analyzed for its capacity to induce fibroblast proliferation, collagen synthesis, collagenolytic activity, and production of tissue inhibitor of metalloproteinase-1. All data were analyzed using the Mann-Whitney U test.

Results:  Aqueous humor derived from patients with POAG induced a significant decrease of functional collagenase activity (mean±SE, 9.12±1.33 μg of degraded collagen per milligram of incubated protein vs 20.94±4.14 μg from the control group, P<.05). The enzymatic activity in the other types of glaucoma was similar to that of controls. The POAG samples had a significantly higher concentration of tissue inhibitor of metalloproteinase-1 (mean±SE, 3.11±0.58vs0.91±0.13 μg/mL from controls; P<.05). The amount of immunoreactive tissue inhibitor of metalloproteinase-1 found in the other three groups was not significantly different from the control. Aqueous humor stimulated fibroblast proliferation in all cases, but significant differences were not observed between the POAG samples (mean±SE, 20285±4642 cpm/mg of incubated protein) and the control group samples (26550±3688 cpm/mg of incubated protein). Primary open-angle glaucoma fluids increased collagen synthesis significantly compared with the control group (mean±SD, 3352±630 vs 985±285, P<.05), and the other groups.

Conclusions:  An increase of collagen synthesis and a decrease of collagen degradation may contribute to an excessive deposit of collagen with loss of the trabecular cells during the development of POAG, and aqueous humor must be considered as a microenvironment that affects the metabolism or function of the trabecular meshwork or both.

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