Fig. 3.

Main cellular sources and targets of IL-17B in IPF. IL-17B is mainly secreted from the epithelium, neutrophils, and B cells. It plays an important role in mediating lung inflammation by stimulating the expression of the inflammatory mediators IL-6, IL-23, TNF-α, IL-1β, and chemokines from macrophages, neutrophils, and Th17 cells. IL-17B induces lung fibrosis by cooperating with TNF-α to stimulate the secretion of Th17-cell-promoting genes and neutrophil-recruiting genes. Th17 T helper cell 17, TNF-α tumor necrosis factor-α, IL-1β interleukin-1β, CXCL12 C-X-C motif chemokine ligand 12, CXCL13 C-X-C motif chemokine ligand 13, IPF idiopathic pulmonary fibrosis