Formaldehyde Gas Exposure Increases Inflammation in an In Vitro Model of Dry Eye

September 1, 2018

doi: 10.1093/toxsci/kfy125

Michael-Adrien Vitoux,* Karima Kessal,* Christophe Baudouin,†,‡ Olivier Laprevote, § Stephane Melik Parsadaniantz, Sophie Achard, , and Francoise Brignole-Baudouin*,†,§
*Institut de la Vision, CNRS UMR 7210, INSERM UMRS 968, Universite Pierre et Marie Curie UM80, Paris 75012, France;
Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, Paris 75012, France;
Hopital Ambroise Pare, APHP, Universit e Versailles Saint-Quentin-en-Yvelines, Boulogne-Billancourt 92100, France;
§Laboratoire de Chimie – Toxicologie Analytique et Cellulaire, UMR8638, Faculte de Pharmacie de Paris, Universite Paris Descartes, Sorbonne Paris Cit e, Paris 75006, France; and
Laboratoire de Sante Publique et Environnement, EA 4064, Faculte de Pharmacie de Paris, Université Paris Descartes, Sorbonne Paris Cité, Paris 75006, France

In this study, we proposed to use an in vitro ALI exposure system to study the combined effects of environmental stresses, namely low humidity, airflow, and the presence of gaseous FA, on the inflammatory responses and cellular death of a conjunctiva-derived cell line. This experimental model could help better understand the impact of pollution on the inflammatory responses observed in the conjunctiva of patients suffering from dry eye disease.

Dry eye (DE) is a multifactorial ocular surface disease whose incidence continues to rise. Various environmental stresses such as low air humidity and pollution are known to be involved in epithelial alterations inducing ocular discomfort. However, no experimental study assessing the combined effects of dry air and polluted atmospheres has been conducted so far. Formaldehyde (FA) is a ubiquitous pollutant present in the living spaces where humans spend most of their time. Using an in vitro DE model, we evaluated the cytotoxic and inflammatory responses of a conjunctival cell line exposed at the air-liquid interface (ALI) conditions to various controlled atmospheres combining low humidity (LH), airflow (AF), and formaldehyde gas (FG). Conjunctiva-derived cells grown onto transwell inserts were directly exposed to LH conditions without AF, with AF or with FG flow at 100 or 1200 mg/m3 for 15–30min. Cell viability assays revealed an increase in cell death after a 15-min exposure to FG at 100 or 1200 mg/m3, whatever the recovery period. After a 1-h recovery period, an increase in IL-6 and CXCL8/IL-8 gene expression was observed with the 15-min exposure at 100 mg/m3 FG and with 30 min of exposure at 1200 mg/m3 FG. After 24 h of recovery, we also noted increased secretion of the proinflammatory cytokine MIF with 100 mg/m3 FG exposure and CXCL8/IL-8 at 1200 mg/m3, for both exposure periods. Together, these findings suggest that the exposure to FG at environmental levels aggravates cell death and inflammation observed in dry air conditions. This in vitro model of DE seems to be a relevant tool to study and explain the inflammatory responses observed in dry eye patients when exposed to combined environmental disturbances such as LH, airflow, and the presence of airborne pollutants.

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