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Mark D. Willcox, Neeta Khandekar, Sharon Shih, Peter A. Simmons, Joseph G. Vehige, Jr., Qian Garrett; Reduction Of Hyperosmotic Stress-induced Corneal Epithelial Cell Apoptosis By Carnitine. Invest. Ophthalmol. Vis. Sci. 2012;53(14):564.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the effectiveness of carnitine in protecting human corneal epithelial cells from apoptosis due to hyperosmotic stress.
Cultured human corneal limbal epithelial (HCLE) cells were exposed to culture medium with or without carnitine (10 mM) at 300 mOsm (isotonic), 450 mOsm (moderate), and 500 mOsm (hyperosmotic) for 16 h. Induction of apoptosis was detected by quantification of the proteolytic activity of caspase-8, caspase-9, or caspase-3/7 using caspase activity assays, and production of tumor necrosis factor (TNF)-α, a known apoptosis inducer, using ELISA. Annexin V and Propidium iodine (PI) staining was performed to detect the percentage of apoptotic cells using confocal microscopy and flow cytometry.
Compared to hyperosmotically stressed HCLE, the presence of carnitine (10 mM) in the hyperosmolar medium (500 mOsm) resulted in significant reduction in cellular caspase-9 activities (33%, p < 0.05) and a decreasing trend for caspase-3/7 activities (20%); significantly reduced TNF-α production (25%) (p < 0.01); as well as significant increase in the percentage of un-damaged (non-apoptotic/non-necrotic) cells (63%) (p < 0.05), indicating decreased apoptosis in the presence of carnitine.
The compatible solute carnitine can inhibit cellular apoptosis of cultured human corneal epithelial cells during hyperosmotic stress.
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