Immunolocalization of prolyl 4-hydroxylase in rabbit lens epithelial cells

Purpose: To localize the enzyme prolyl 4-hydroxylase in the crystalline lens and determine the ability of lens epithelial cells (LECs) to synthesize procollagen. Setting: Research laboratory, Department of Ophthalmology, Wakayama Medical College, Wakayama, Japan. Methods: Phacoemulsification and aspiration of the crystalline lens followed by implantation of a poly(methyl methacrylate) intraocular lens (IOL) were performed in 1 eye each of 6 albino rabbits; the eye was enucleated 1 or 2 months later. Crystalline lenses were also extracted from the eyes of 2 rabbits. These samples were processed for immunohistochemical detection of the alpha- and beta-subunits of prolyl 4-hydroxylase. Results: A monolayer of LECs was detected on the inner surface of the intact anterior capsule. Antibodies directed against both subunits of prolyl 4-hydroxylase reacted strongly to LECs proliferating on capsules with IOLs, whereas little or no reaction was observed in quiescent LECs or in the regenerated lenticular structure. Conclusion: The presence of prolyl 4-hydroxylase in LECs proliferating on the inner surface of the lens capsule suggests that these cells are involved in the production of procollagen and fibrosis during capsular injury and repair. Suppression of prolyl 4-hydroxylase activity may prevent the capsule opacification that results from cataract removal and IOL implantation.