It has been shown that the lung microbiota plays a role in regulating Th1/Th2 during fibrotic injury, with an enhanced response of FOXP3 + T-regulatory cells, which can promote collagen deposition (O'Dwyer et al., 2019), and FOXP3 + T-regulatory cells can facilitate lung fibrosis by stimulating fibroblasts through the secretion of PDGF-B (Lo Re et al., 2011). Here, FOXP3 is linked to pulmonary fibrosis.