SPP1 and pulmonary fibrosis: Within the BALF, levels of tumor necrosis factor-α (TNFα), osteopontin (OPN), monocyte chemoattractant protein-1 (MCP-1), and surfactant protein-D (SP-D) were significantly elevated in both wild-type (WT) and TG mice with lung fibrosis, compared to their respective saline-treated controls.