IGF1 and pulmonary fibrosis: Previous studies have shown that macrophages release various cytokines, including interleukin-1 (IL-1), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF- α), transforming growth factor-beta (TGF- β), matrix metalloproteinases (MMPs), and insulin-like growth factor 1 (IGF-1)], to regulate epithelial cell proliferation, fibroblast activation, angiogenesis, and ECM deposition, leading to pulmonary fibrosis (20–22).