These data support previous studies showing that MCs can drive fibrosis and tissue remodeling through the recruitment of immune cells and production of pro-fibrotic mediators, such as TGFβ, CCL2, tryptase, and IL-13.27 We did not detect eosinophils in the BAL fluid in the experimental COPD or BLM models. Here, TGFB1 is linked to chronic obstructive pulmonary disease.