Figure 4.

Identification of factors produced by LPS-treated AECs that induce IGF-1 secretion by AMs. (A) AECs (2 ×10⁵ cells/well) were inoculated into a 24-well plate and stimulated with LPS (10 ng/mL) for 2, 8, and 24 h. The supernatants were analyzed by ELISA for IL-6, GM-CSF, IL-1β, MCP- 1, TNF-α, and TGF-β content. **P < 0.01 vs. the 2 h group. (B) Primary AMs (1 ×10⁶ cells/well) were inoculated into 6-well plates and stimulated h with different concentrations (1, 10, 100, and 1,000 ng/mL) of IL-1β, TNF-α, MCP-1, and TGF-β for 24 h. The IGF-1 content in AM-CM was measured by ELISA. *P < 0.05 and **P < 0.01 vs. the 0 ng/mL group. (C) Primary AMs (1 ×10⁶ cells/well) were inoculated into 6-well plates and stimulated with TGF-β (100 ng/mL) for 24 h. The expression level of IGF-1 in AMs was detected by western blotting. **P < 0.01 vs. the control group.