Flagellin Induces Pro-inflammatory Cytokines, Chemokines and Metalloproteinases In Bronchial Epithelial Cells.

Abstract

RATIONALE: Flagellin which is abundant in gram-negative bacteria including pseudomonas is reported to be related with development of asthma. However, its effect on airway epithelial cells regarding asthma pathogenesis is not elucidated yet. We investigated the effect of flagellin on the production of cytokines, chemokines and metalloproteinase related with airway inflammation and remodeling in the primary human epithelial cells. METHODS: Primary human bronchial epithelial cells were grown and differentiated in air-liquid interface culture for 14-16 days. The cells were treated with flagellin in vitro at 10 and 100ng/ml for 3, 24, and 48hours. The conditioned media and cells were harvested to measure cytokines, chemokines and metalloproteinase related with asthma and their mRNA expressions by ELISA or western blot and quantitative PCR, respectively. RNA-sequencing was performed to screen the up-regulated and downregulated transcriptomes by flagellin. RESULTS: Flagellin upregulated mRNA expressions of GM-CSF at 3hrs of treatment and increased GM-CSF secretion significantly at 24hr in conditioned media. Flagellin enhanced mRNA expressions and secretions of CCL5, CXCL10, CXCL11 chemokines, which were detected in the RNA-sequencing. In addition, mRNA expressions and protein productions of MMP9 and MMP13 were also enhanced by flagellin. TGF-b1 and TGF-b2 augmented the mRNA expressions of GM-CSF, MMP9 and MMP13 induced by flagellin. CONCLUSIONS: Flagellin is an inducer of cytokines, chemokines and metalloproteinase contributing to airway inflammation and remodeling in bronchial epithelial cells. Further studies are needed to clarify their interaction with other inflammatory and structural cells and clinical implications in terms of asthma.Abstracts AB187 SUNDAY