Benzalkonium chloride-induced direct and indirect toxicity on corneal epithelial and trigeminal neuronal cells: proinflammatory and apoptotic responses in vitro

• Published in: Toxicology letters Vol. 319; pp. 74 - 84
• Main Authors: Vitoux, Michael-Adrien, Kessal, Karima, Melik Parsadaniantz, Stéphane, Claret, Martine, Guerin, Camille, Baudouin, Christophe, Brignole-Baudouin, Françoise, Réaux-Le Goazigo, Annabelle
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.02.2020; Elsevier
• Subjects: Activating Transcription Factor 3 - biosynthesis; Activating Transcription Factor 3 - drug effects; Animals; Apoptosis - drug effects; Benzalkonium chloride; Benzalkonium Compounds - toxicity; Cell Line; Conditioned medium; Corneal epithelial cells; Dry Eye Syndromes - chemically induced; Dry Eye Syndromes - pathology; Epithelial Cells - drug effects; Epithelium, Corneal - cytology; Epithelium, Corneal - drug effects; Gene Expression - drug effects; Humans; Inflammation - chemically induced; Inflammation - pathology; Life Sciences; Male; Mice; Mice, Inbred C57BL; Neuronal injury; Neurons - drug effects; Ocular inflammation; Oxidative Stress - drug effects; Preservatives, Pharmaceutical - toxicity; Signal Transduction - drug effects; Trigeminal Ganglion - cytology; Trigeminal Ganglion - drug effects; Trigeminal neurons; Corneal epithelial cells; DED; TG; Conditioned medium; Trigeminal neurons; HCEc; Neuronal injury; Benzalkonium chloride; CM; BAK; Ocular inflammation
• ISSN: 0378-4274; 1879-3169; 1879-3169
• DOI: 10.1016/j.toxlet.2019.10.014

•Benzalkonium chloride induces toxicity on human corneal epithelial cells.•Conditioned medium from corneal cells exposed to BAK (BAK-CM) triggers neuronal genes.•BAK-CM enhances neuronal damage and inflammatory genes at an early stage.•BAK-CM activates pro-survival pathways in neurons at a late stage. Benzalkonium chloride (BAK), a quaternary ammonium compound widely used as disinfecting agent as well as preservative in eye drops is known to induce toxic effects on the ocular surface with inflammation and corneal nerve damage leading to dry eye disease (DED) in the medium-to-long term. The aim of this study was to evaluate in vitro the toxicity of a conditioned medium produced by corneal epithelial cells previously exposed to BAK (BAK-CM) on trigeminal neuronal cells. A human corneal epithelial (HCE) cell line was exposed to 5.10−3% BAK (i.e. 0.005% BAK) for 15 min and let recover for 5 h to prepare a BAK-CM. This BAK concentration is the lowest one found in eye drops. After this recovery period, BAK effect on HCE cells displayed cytotoxicity, morphological alteration, apoptosis, oxidative stress, ATP release, CCL2 and IL6 gene induction, as well as an increase in CCL2, IL-6 and MIF release. Next, a mouse trigeminal ganglion primary culture was exposed to the BAK-CM for 2 h, 4 h or 24 h. Whereas BAK-CM did not alter neuronal cell morphology, or induced neuronal cytotoxicity or oxidative stress, BAK-CM induced gene expression of Fos (neuronal activation marker), Atf3 (neuronal injury marker), Ccl2 and Il6 (inflammatory markers). Two and 4 h BAK-CM exposure promoted a neuronal damage (ATF-3, phospho-p38 increases; phospho-Stat3 decreases) while 24 h-BAK-CM exposure initiated a prosurvival pathway activation (phospho-p44/42, phospho-Akt increases; ATF-3, GADD153, active Caspase-3 decreases). In conclusion, this in vitro model, simulating paracrine mechanisms, represents an interesting tool to highlight the indirect toxic effects of BAK or any other xenobiotic on corneal trigeminal neurons and may help to better understand the cellular mechanisms that occur during DED pathophysiology.