TLR4 and pulmonary fibrosis: Moreover, paricalcitol decreased pulmonary toll-like receptor 4 (TLR4), nuclear factor kappa B (NF-κB) p65, tumor necrosis factor alpha (TNF-α), transforming growth factor-beta 1 (TGF-β1), and phosphorylated small mothers against decapentaplegic 3 (pSmad 3) levels in line with less lung fibrosis percentage.