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Mary Feng, Julia Baryla, Hong Liu, Gordon Laurie, Robert McKown, Negin Ashki, Dinesh Bhayana, Cindy Hutnik; Cytoprotective effect of lacritin on human corneal epithelial cells exposed to benzalkonium chloride. Invest. Ophthalmol. Vis. Sci. 2013;54(15):973.
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Benzalkonium chloride (BAK) is the most commonly found preservative in eye drops, and has been shown to cause ocular surface inflammation and toxicity. Lacritin is a human tear glycoprotein secreted from the lacrimal glands that has been found to be cytoprotective. This study was designed to determine if the prosecretory and mitogenic properties of lacritin confer protection to a cultured human corneal epithelial (HCE) cell line, CRL-11515, and primary HCE cells after exposure to the ocular preservative agent BAK.
Recombinant human lacritin and negative control fragment C-25 were cloned into intein fusion vectors, expressed in E. coli, and purified on chitin beads and DEAE Sepharose. Metabolic curves were established after exposure of subconfluent CRL-11515 cells to BAK or lacritin. Western blot analysis of lipidated LC3 (LC3-II) provided a measure of autophagy in CRL-11515 cells exposed to lacritin and/or BAK.
BAK reduced CRL-11515 cellular metabolic activity in a time and dose dependent manner. BAK-induced cellular stress was evident by elevated autophagy that increased with rising concentrations of BAK compared to control (P<0.05). Lacritin increased HCE cell proliferation at an optimal dose of 1 nM. Preconditioning HCE cells with 1 nM lacritin for 24 hours prior to BAK exposure significantly dampened levels of LC3-II (P<0.05) and promoted a 12% increase in cellular metabolic activity (P<0.01) when compared to BAK alone.
These results suggest lacritin protects cultured HCE cells stressed with BAK and it may have the potential to be used as a topical adjunctive therapy in eyes chronically exposed to BAK.
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