Mast Cells Induce Rat Pulmonary Fibroblast Proliferation and Differentiation via Direct Cell–Cell Contact

Abstract

We investigated whether direct cell–cell contact between mast cells (MCs) and pulmonary fibroblasts (PFs) was important for PF proliferation, differentiation, and function, which are critically involved in the development of idiopathic pulmonary fibrosis. MCs and PFs were isolated from male Wistar rats for 3 experimental conditions: (1) PFs alone (Controls); (2) co-culture and contact (CC) between MCs and PFs; and (3) co-culture and no contact (NC) between MCs and PFs. We monitored PF proliferation using growth curves and MTT assays, evaluated PF expression of α-smooth muscle actin (α-SMA) by immunocytochemistry, and determined the concentrations of bFGF, TGF-β1, and Type I collagen in culture supernatants by ELISA. After 5 days in culture, CC conditions induced a significant increase in PF proliferation compared to the other 2 conditions. No significant difference was observed between the NC and control conditions. CC conditions also induced significantly higher PF expressions of α-SMA, and bFGF, TGF-β1, and Type I collagen production compared to the other 2 conditions. These results suggest that MCs promote both PF proliferation and their differentiation into myofibroblasts via direct cell–cell contact.