TNF and idiopathic pulmonary fibrosis: Pro-inflammatory cytokines which in vitro stimulate fibroblast proliferation and chemotaxis, but inhibit collagen production. Upregulated in the bleomycin model, and overexpression in vivo induces inflammation and fibrosis, with fibrosis likely mediated by TGF-β. Inhibition of TNF-α in patients with IPF did not improve outcomes.