HGF and pulmonary fibrosis: In a mouse model of bleomycin-induced pulmonary fibrosis, administration of anti-KL-6 antibody following bleomycin administration reduced the number of BALF inflammatory leukocytes, diminished the content of hydroxyproline in lung tissues, reduced the expression of collagen type I, TGF-β, and KL-6, increased hepatocyte growth factor (HGF) expression, and inhibited airway epithelial cell apoptosis (185).