Effects of the eye drop preservative Benzalkonium Chloride on lipidome of human conjunctival cells in vitro

Abstract

Purpose : Benzalkonium chloride (BAK) is the most commonly used eye drop preservative. BAK has been associated with toxic effects such as dry eye symptoms and trabecular meshwork degeneration in long term treated glaucoma patients. Nevertheless, the underlying biochemical mechanism of ocular toxicity induced by BAK remain unclear and involve oxidative stress, apoptosis and inflammation in ocular surface cells. Both inflammatory processes and cell death phenomena may involve second messengers derived from lipids. Currently, very sparsely data are available regarding lipid metabolism alteration following BAK exposure.
Our purpose was thus to investigate effects of BAK exposure on human conjunctival cell line (IOBA-NHC) on cell lipidome.

Methods : IOBA—NHC cell line were exposed to 10^-4% and 2.10^-4% of BAK for 24 hours. Following cell pellet lipid extraction, lipidomic analysis were performed by ultra-performance liquid chromatography hyphenated to quadripole-time-of-flight high resolution mass spectrometer with electrospray in both negative and positive mode (UPLC-qTOF-HRMS-ESI+/-). Multivariate statistical analyses were then achieved in order to identify lipids modified by BAK exposure in IOBA-NHC cells.

Results : Our results demonstrated that BAK induced striking modifications of IOBA-NHC lipidome including major changes in sphingolipids, glycerolipids and glycerophospholipids. BAK especially increase ceramide level which are lipid species involved in pro-inflammatory processes and cell death phenomena. BAK exposure led to both a striking decrease in PC and an increase in LPC suggesting an activation of phospholipase A2_, the enzyme responsible for the SN₂ acyl chain hydrolysis of phospholipids. Furthermore, BAK induced a decrease in plasmalogen species which are involved in oxidative stress defense.

Conclusions : This study highlights changes in the levels of lipids involved in inflammatory responses and cell death pathways following BAK exposure which give new insight in toxic effect of glaucoma treated patients with preservative eye drop.

This is a 2020 ARVO Annual Meeting abstract.