The Effect Of TNFα On Morphology Of Outflow Pathways In Rat Eyes

Purpose On the basis of observation of morphology and definition of components of extra cellular matrix in aqueous outflow pathways of SD rat eyes, to investigate when the concentration of tumor necrosis factor ( TNF) a increased in aqueous, whether it will induce the expression and secretion of trabecular stromelysin, and then initiate the remodeling of the trabecular extra cellular matrix.Materials and Methods Thirty SD rats, feeding in clearing grade standard, were classified into five groups at random. Application of transmission electron microscopy, scanning electron microscopy, light microscopy and immunohistological staining methods, normal morphology of outflow pathways was observed and component of extra cellular matrix was defined. The effects of 50 IU of TNF-a given intracamerally on the morphology of outflow pathways and other tissues of anterior segments , expression of trabecular stromelysin and the change of components of trabecular extra cellular matrix were observed in 24h, Sdays ,7days and 14days after injection.Results The eyes of SD rats have a canal of Schlemm. Trabecular meshwork consist of 2? connective tissue lamella covered by trabecular endothelial cells. Large giant vacuoles and pores occurred in the lining endothelium of Schlemm's canal in SD rat eyes. The staining intensities of collagen types ffl , V , fibronectin and lamina showed statistically significant differences compared with the control sections, but no differences in collagen types IV , \1. The eyes treated with TNF-a showed a statistically significant increase of activities of trabecular stromelysin compared with the contralateral control eyes 24h after injection, but returned to normal levels in 3 days. The staining intensities of collagen types ffl , V , fibronectin showed statistically significant decrease in the eyes treated with TNF-a compared with the contralateral control eyes 3 days after injection, but no differences in 24h, 7days and 14days groups were found. There was no difference in lamina in all groups, inflammation in the eyes with paracentesis was found. It caused edema of mitochondria in corneal endothelium and increase of homogeneous substance between endothelia. These changes improved obviously when inflammation in anterior chamber disappeared. No obvious pathological lesions occurred in ultrastructure of lens epithelia and lens cells.Conclusion Not only in morphology of outflow pathways, but also in some mechanisms, SD rat eyes shared many features of primate outflow system. There were collagen types ffl , V , fibronectin and lamina in the extra cellular matrix in outflow pathways of SD rat eyes. TNF-a can induce the expression and secretion of trabecular stromelysin, and dissolved collagen types ffl , V , fibronectin. 50IU of TNF-a given intracamerally, no irreversible acute damage to the corneal endothelia and lens was observed.