TNF and pulmonary fibrosis: Furthermore, in a bleomycin-induced lung fibrosis model, injection of WJ-MSCs downregulated the expression of pro-fibrotic and proinflammatory cytokines, including TGF-β, interferon-γ (IFN- γ), tumor necrosis factor-α (TNF- α), and macrophage migration inhibitory factor, while promoting ECM degradation through the upregulation of MMP-2 expression [32].