FN1 and asthma: In summary, various studies have shown that asthma-derived eosinophils interact with fibroblasts to stimulate the over production of ECM proteins (e.g., collagen I, collagen II, fibronectin, elastin, α-SMA) and profibrotic cytokines such as TGF-β that are implicated in asthma fibrosis (42, 61, 62).