004 PM induce TGF-β production by bronchial epithelium, suggesting an auto-inhibitory effect on cell renew

Abstract

Atmospheric pollutants act efficiently on immune response, facilitating airway inflammatory reaction to antigen and non-specific stimuli. Bronchial epithelial cell is immediately implicated in this process. To gain new insights in the roles of this natural barrier in context of pollution, we investigated the effect of suspended particulate matter (SPM) on epithelium for cytokine, growth factor production and cell proliferation. SPMs were collected from Lyon city area, using TEOM collector, filtered, then resuspended in distilled water. SV-40 transformed-foetal human bronchial epithelial cell Une (WI26VA4) was cultured in MEM for at least 60% of confluence, then incubated for 48h at 37°C, in the absence, or in the presence of SPM (PI < 0.2 μm, 0.2 < P2 <0.8 μm, 0.8 < P3 <10 μm and PT a mixture of SPM < 10 μm) at 5, 10 or 20 μg/ml. Proliferation was assessed by cell counting at 48h. IL-8 and TGF-β productions were measured in the cell culture supernatant using ELISA kits (R&D Systems). Cell survival assessed by blue trypan coloration was not altered following 48h of culture in the presence of SPM. After 48h of culture, cell count was diminished by 36.8% in the presence of SPM at 20 μg/ml when compared to media alone (p < 0.01), with a dose-response effect (14 and 22% of inhibition using SPM at 5 and 10 μg/ml respectively, p < 0.01). SPM size did not influence significantly cell counting. Additionally, TGF-P production was significantly increased in the presence of PI and P3 fractions of pollutant at 10 and 20 μg/ml, by 0.4 and 0.7 fold respectively (p < 0.01). Finally, IL-8 production was 2.4-fold higher when epithelial cells were cultured with SPM, irrespective of particulate size and concentration. Our data confirm that SPM acts as an inflammatory stimulus on epithelial cell, inducing an intense IL-8 production, which is implicated in neutrophil recruitment. Furthermore, by initiating a TGF-P production in an autocrine manner, SPM diminishes epithelial renewing, which might favor subsequent inflammatory exacerbation.