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D.J. Rhee, J.L. Martin, D.–J. Oh; SPARC Level in Human Aqueous Humor and SPARC Expression in Cultured Human Trabecular Meshwork and Ciliary Body following Latanoprost . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1876.
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© ARVO (1962-2015); The Authors (2016-present)
SPARC mediates communication between cells and extracellular matrix (ECM). Increased ECM in the trabecular meshwork (TM) is associated with open–angle glaucoma. We examined aqueous SPARC levels in glaucoma and cataract eyes and SPARC expression in cultured TM and ciliary body smooth muscle (CBSM) cells following latanoprost.
Aqueous samples were taken during trabeculectomy or cataract surgery in glaucoma or cataract eyes, respectively. SPARC levels were determined by indirect enzyme–linked immunosorbent assay (ELISA). Explant cultures of TM and CBSM cells from 3 donors were treated with latanoprost at a pharmacologic level of 0.03 µg/ml for 1, 3, and 7 days. Changes in mRNA expression of SPARC were assessed using quantitative reverse transcription–polymerase chain reaction (qRT–PCR) in control and treated cultures of TM and CBSM cells. Changes in SPARC protein levels were examined using immunoblotting and ELISA.
In aqueous samples, 60% of glaucoma eyes (n=35) had SPARC concentrations above 120 ng/ml compared with 20% of cataract eyes (n=7) (p<0.001). However, the mean SPARC concentration was 116.7±13.5ng/ml in glaucoma eyes and 108.9±10.5 ng/ml in cataract eyes (p=0.12). SPARC levels did not correlate with baseline intraocular pressure (IOP), historical IOP maximum, or age. All glaucoma patients were on topical prostaglandins. In TM cells, latanoprost did not change SPARC mRNA of 2 donors at day 1, but decreased 12% at day 3 and 28% at day 7. 1 donor had a decrease of 12% and decreased 27% at day 3 and 40% at day 7. Immunoblot staining did not change at day 1, but increased 5% at day 3 and 41% at day 7. Latanoprost did not change free SPARC levels compared to controls (15 ng/ml/106cells) at 1–, 3–, or 7–days.
In CBSM cells, latanoprost increased SPARC mRNA of 2 donors at day 1, but decreased 14% at day 3 and then increased up to 100% at day 7. 1 donor did not change at day 1, but decreased 20% at day 3 and returned to normal level at day 7. Immunoblot staining increased 70% at day 1, 15% at day 3, and 96% at day 7. Free SPARC level did not change compared to controls (110 ng/ml/106cells) at day 1, but increased 10% at day 3 and day 7.
Aqueous SPARC levels were similar in cataract and glaucoma eyes. Latanoprost did not have a significant effect on TM cells in SPARC expression, but increased SPARC expression in CBSM cells. SPARC may be involved in IOP regulation.
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