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R. A. Lalane, III, P. Challa, R. Vann, P. V. Rao; Aqueous Humor Derived From Human Patients With Primary Open-Angle Glaucoma Contains Increased Levels of Secretory Gelsolin. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6105.
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To evaluate potential changes in levels of secretory gelsolin, which is known to prevent amyloid fibril aggregation, extracellular actin aggregation and inflammation, in aqueous humor samples from human subjects with primary open angle glaucoma, pseudoexfoliation and from normal individuals.
Human aqueous humor samples were collected from patients who underwent cataract or glaucoma surgery at the Duke Eye Center. Gelsolin protein levels were determined by quantitative immunoblot analysis and expressed per unit volume of aqueous humor. The non-parametric Wilcoxon rank sum tests were used to assess statistical significance of differences between groups. To determine if trabecular meshwork (TM) cells secrete gelsolin, conditioned media derived from human and porcine TM cells were analyzed by immunoblotting. To identify possible binding partners of gelsolin in aqueous humor, immunoprecipitation using an anti-gelsolin antibody was performed and the coimmunoprecipitated proteins were subsequently identified by mass spectrometry analysis.
Analysis of a total of forty individual human aqueous humor samples (n=23 cataract; n=8 POAG; n=9 psx) for gelsolin levels yielded results in a concentration range of 2.5-25 ng/µL. Aqueous humor gelsolin levels were significantly higher in patients with POAG relative to patients with either cataracts (p<0.01) or pseudoexfoliation (p<0.01). There was no difference in aqueous humor gelsolin protein levels between pseudoexfoliation and cataract patients (p<0.36). Gelsolin was readily detected in the conditioned media of both human and porcine TM cell cultures. Vinculin and fibronectin type III proteins were identified as potential binding partners of extracellular gelsolin via immunoprecipitation analysis in conjunction with mass spectrometry.
This study confirms the presence of secretory gelsolin in human aqueous humor and indicates that gelsolin appears to be secreted by the cells of aqueous humor outflow pathway and other cells of the eye anterior chamber. Most importantly, the levels of secretory gelsolin in aqueous humor derived from primary open angle glaucoma patients were elevated significantly as compared to age-matched cataract and pseudoexfoliation subjects. These observations not only implicate the possible involvement of gelsolin in glaucoma but also warrant further studies on understanding the cellular basis and pathophysiological significance of elevated levels of gelsolin in aqueous humor of glaucoma patients.
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