The five main isoforms of the human Organic Cation Transporters (OCT), i.e., OCT1, OCT2 OCT3, OCTN1 and OCTN2 have been detected in the pulmonary tissue (1, 2) and there is published evidence these transporters impact on the absorption of inhaled drugs across the airway epithelium (2,3). In contrast, their physiological roles in the lungs have hardly been explored. It has been reported that OCT1 and OCT2 mediated the release of the non-neuronal acetylcholine from bronchial epithelial cells into the lung fluid (4) and that the OCT1-3 genes were dysregulated in the lungs of rodents following an acute ovalbumin challenge (5). However, the pathophysiological implications have not been investigated to date. Since the airway epithelium is the primary protection barrier in the lungs, we initially assessed how environmental insults associated with chronic inflammatory pulmonary diseases affected OCT expression in bronchial epithelial cells. Layers of the human bronchial epithelial cell line Calu-3 cultured on permeable filters at an air-liquid interface for 21 days were used as a physiologically relevant in vitro model of the bronchial epithelium. Similarly to normal human bronchial epithelial cell layers, these expressed OCT1, OCT3, OCTN1 and OCTN2 while OCT2 could not be detected (6). Calu-3 layers were exposed to lipopolysaccharide (LPS), a common pro-inflammatory stimulant, for 48h or to the aeroallergen house dust mite (HDM) for 8h twice over 48h. In parallel, they were also ‘scrape’ wounded using a pipette tip and allowed to recover for 48h. Changes in OCT gene and protein expression were measured by quantitative polymerase chain reaction (qPCR) or ‘In-cell’ Western, respectively. All three epithelial insults caused fold increases in the expression of OCT1, OCT3 and OCTN2 while OCTN1 was exclusively upregulated upon exposure to HDM at a concentration that compromised the integrity of the cell layer tight junctions (TJ). Interestingly, a non TJ disruptive concentration of the allergen only enhanced the expression of OCTN2. Subsequently, the alveolar epithelial cell line A549 was used to evaluate the potential roles of OCT1 and OCTN2 in the mechanism of epithelial healing after injury as well as in airway protection against inflammation. The gene of the two transporters was successfully knocked down in the cell line using targeted siRNA. Knocked down layers grown on tissue culture plates were either scratched or challenged with LPS for 6h. Cell recovery after wounding was monitored by time lapse microscopy and by the Presto Blue® cell viability assay while the production of reactive oxygen species (ROS) upon LPS stimulation was measured using the dichlorofluorescein diacetate dye. In contrast to wild type cells, both OCT1 and OCTN2 knocked down layers failed to repair within 48h. In addition, low expression of the two transporters resulted in an increase in ROS formation following cell exposure to LPS. Our data demonstrated that OCT expression in airway epithelial cells is affected by a pro-inflammatory stimulus, an allergen abuse and physical damage, with possible consequences in chronic inflammatory respiratory diseases. They also suggest OCT1 and OCTN2 participate in the repair of the airway epithelium after injury and might play a role in the control of oxidative stress during airway inflammation. The underlying mechanisms remain however to be investigated.