The neurotrophic factor (NTF) family has recently expanded its role beyond neurological conditions, but its involvement in acute inflammatory lung diseases remains largely unclear. Using well-established acute lung injury (ALI) and sepsis models, we demonstrate that brain-derived neurotrophic factor (BDNF), a key NTF, is impaired in pulmonary epithelial cells and negatively correlates with the inflammatory response. Raising the BDNF level alleviates inflammatory lung injury, but these effects are absent in macrophage-deleted mice. Both in vivo and in vitro results show BDNF inhibits macrophage inflammation, and further proteomics analysis identifies macrophage TLR4 as a receptor that BDNF antagonizes via direct binding. The BDNF fragment (aa 104-115) is critical for BDNF-TLR4 interaction, and the corresponding synthetic BDNF-derived dodecapeptide (BDP-12) retains TLR4-antagonistic and anti-inflammatory effects both in vitro and in vivo, without pro-proliferative side effects. In conclusion, our findings reveal that epithelial-derived BDNF prevents macrophage inflammation by directly targeting TLR4 and highlights BDP-12 as a potential therapeutic agent for acute inflammatory diseases.
Zhu et al. (Sat,) studied this question.