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Abstract #6356 Published in IGR 3-2
Reduced TIGR/myocilinprotein in the monkey ciliary muscle after topical prostaglandin F2α treatment
Lindsey JD; Gaton DD; Sagara T; Polansky JR; Kaufman PI; Weinreb RNInvestigative Ophthalmology and Visual Science 2001; 42:1781-1786
PURPOSE: Mutations in the trabecular meshwork inducible glucocorticoid response (TIGR) gene, also known as myocilin, have recently been linked to some forms of glaucoma. Recent studies have shown that TIGR protein is also expressed in the ciliary muscle. Because uveoscleral outflow, which traverses the ciliary muscle, is increased by prostaglandins (PGs), the present study assessed whether topical PGs alter the amount of TIGR protein within the ciliary muscle. METHODS: Vehicle was topically applied to one eye, and 2 μg PGF2α-isopropyl ester (PGF2α-IE) to the other eye of cynomolgus monkeys twice daily for five days. Pressure reductions of 5 mmHg in the PGF2α-IE-treated eyes were confirmed. The eyes were then fixed and paraffin sections were cut from each eye. The distribution of TIGR protein in the ciliary muscle was determined by confocal scanning laser microscopy. Additional sections were immunostained with a polyclonal antibody to recombinant TIGR protein or with a polyclonal antibody to a synthetic peptide corresponding to the leucine zipper region within the TIGR protein. Staining intensity in the ciliary muscle was assessed by measuring optical density (OF) along two line segments overlying the ciliary muscle, by using a high-resolution imaging densitometer. RESULTS: TIGR protein immunoreactivity was observed in ciliary muscle fibers throughout the ciliary muscle. Extracellular TIGR immunoreactivity colocalized with collagen type IV immunoreactivity. Intracellular staining was also present. Immunoreactivity was less intense in the sections from the PGA2α-IE-treated eyes compared to the vehicle-treated eyes. This was reflected in the reduction of mean OF scores in each monkey. Overall, the reduction of mean OF scores in the treated eyes was 41.2 ± 9.9% (p < 0.005) with the anti-recombinant TIGR antibody, and 27.3 ± 10.4% with the anti-TIGR peptide antibody (p < 0.005). CONCLUSIONS: TIGR protein immunoreactivity was present both intracellularly and extracellularly in the ciliary muscle of the cynomolgus monkey. This suggests that extracellular TIGR protein is in contact with aqueous humor in the uveoscleral outflow pathway. Moreover, intraocular pressure-lowering topical PGF2α-IE treatment decreases the amount of TIGR protein in the ciliary muscle.
Dr R.N. Weinreb, Glaucoma Center, University of California San Diego, 9500 Gillman Drive, La Jolla CA 92093-0946, USA. weinreb@eyecenter.ucsd.edu
Classification:
3.3 Immunohistochemistry (Part of: 3 Laboratory methods)
2.9 Ciliary body (Part of: 2 Anatomical structures in glaucoma)
11.4 Prostaglandins (Part of: 11 Medical treatment)
