Abstract
Inflammatory processes related to lung involve multiple factors which may lead to pulmonary fibrosis and lung scarring. Among which asthma causes subepithelial fibrosis in the airway, an eosinophil inflammation process induced by human eosinophil cationic protein (hECP). Our lab has demonstrated that ECP binds cell surface glycosaminoglycan (GAGs), especially heparan sulfate proteoglycans (HSPGs) on bronchial epithelial cells and enters the cells by macropinocytosis. In addition, recent reports indicate that circulating cells (i.e., the fibrocytes) contributing to the evolution of pulmonary fibrosis are induced by increased expression of certain cytokines. For example, an inflammation cytokine CXCL-12, a ligand for CXCR-4, involves in recruitment of fibrocyte to the lung. In this study, the question is what the influence is when ECP enters Beas-2B cells and induces inflammatory response. Here mRNA and protein expression variation of cytokines in Beas-2B cells upon stimulation with ECP was respectively determined by real-time PCR and ELISA. The chemotaxis of fibrocyte under ECP induced lung inflammation was mimicked by transwell and micro-fluidic chip system to monitor microenvironmental changes. Upon treatment with recombinant ECP, both mRNA and protein expression levels of CXCL-12 increased in a dose- and time-dependent manner. Interestingly, fibrocyte were recruited towards Beas-2B cells in both transwell and micro-fluidic lab chip systems, but the latter showed higher efficiency than the former. In summary, we have established a novel in vitro biomimetic microsystem to simulate blood circulation in the body by monitoring microenvironmental changes and mechanisms of inflammatory process. ECP induced CXCL-12 expression plays a critical role in airway inflammation and pulmonary fibrosis.