TGFB1 and pulmonary fibrosis: It is interesting to note that, in patients with idiopathic pulmonary fibrosis (IPF), Th17 cells secrete TGFβ and IL-17A at high levels; in addition, when lung fibrosis was induced in vitro through bleomycin (BLM) treatment of a murine model or when Th17 cells were cultured simultaneously in the presence of human lung fibroblasts, an increase in collagen deposition and other ECM factor production was revealed [54].