Eosinophils restrict diesel exhaust particles induced cell proliferation of lung epithelial A549 cells, vial interleukin-13 mediated mechanisms: implications for tissue remodelling and fibrosis

Abstract

Diesel exhaust particulates (DEPs) affect lung physiology and cause serious damage to the lungs. A number of studies have demonstrated that eosinophils play a very important role in the development of lung tissue remodelling and fibrosis. However, the exact mechanism of its pathogenesis is not known. We for the first time demonstrate that, Interleukin-13 plays a very important role in the development of tissue remodelling and fibrosis. We demonstrate that, Diesel exhaust particle significantly induce eosinophils cell proliferation and interleukin-13 release in invitro culture conditions. Supernatant collected from DEP induced eosinophils cells significantly restrict cell proliferation of epithelial cells due to exposure of diesel exhast particles. Furthermore, purified interleukin-13 decreases the proliferation of A549 cells. Notably, Etoricoxib (selective COX-2 inhibitor) did not inhibit DEP-triggered release of interleukin-13, suggesting another cell signalling pathway. In, vivo exposer of DEP to the mice lung, resulted in the high level of eosinophils degranulation as depicted by the EPX-1 immunostaining and altered level of mRNA expressions of inflammatory genes. We also found that, a-SMA, fibroblast specific protein (FSP-1) has been changed in response to DEP in the mice lungs along with the mediators of inflammation. Altogether, we elucidated the mechanistic role of eosinophils in the DEP triggered proliferation of lungs cells thus providing an inside in the pathophysiology of tissue remodelling and fibrosis of lungs.