IGF1 and pulmonary fibrosis: M2 macrophages provide an important microenvironment for pulmonary fibrosis by secreting profibrotic substances such as CCL18, IL-10, TIMP1 (tissue inhibitors of metalloproteinases 1), TGF-β, FGF, PDGFα, IGF1, and VEGF (Prasse et al., 2006; Heukels et al., 2019; Wang et al., 2021).