Phillyrin counters β2 integrin-mediated neutrophil adhesion and chemotaxis to alleviate endotoxin-induced acute lung injury in neonatal rats

Acute lung injury (ALI) in neonates presents a grave threat to infant health, characterized by a heightened risk of mortality. Phillyrin, an extraordinary constituent derived from a traditional Chinese medicinal herb Forsythia suspensa , has garnered considerable attention for its pronounced anti-inflammatory properties. However, its therapeutic potential for acute inflammatory diseases in neonates remains unclear. Therefore, our current study endeavors to assess the protective effects of phillyrin against lipopolysaccharide (LPS)-induced ALI in neonates and elucidate the underlying mechanisms. Phillyrin exhibited significant amelioration of lung damage in neonatal rats with LPS-induced ALI, accompanied by reductions in the total cell counts, neutrophil counts, and total protein level in bronchoalveolar lavage fluid (BALF). Notably, phillyrin substantially attenuated proinflammatory cytokine secretion and suppressed NF-κB activation in the lungs of neonatal ALI rats; however, it demonstrated inefficacy in mitigating LPS-induced cytokine secretion and NF-κB activation in vitro . Notably, phillyrin effectively inhibited β2 integrin-mediated neutrophil adhesion, migration, and chemotaxis. Moreover, phillyrin robustly suppressed β2 integrin engagement-induced actin polymerization and the Vav1/Rac1/PAK1/LIMK1/cofilin pathway. From a mechanistic standpoint, phillyrin exhibited direct interaction with β2 integrin, effectively antagonizing its function and significantly disrupting its binding affinity to intercellular adhesion molecule 1 (ICAM-1). This investigation unveils the promising therapeutic prospects of phillyrin as a novel compound against neonatal ALI.