Natural pachypodol integrated, lung targeted and inhaled lipid nanomedicine ameliorates acute lung injury via anti-inflammation and repairing lung barrier

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is a high-mortality disease caused by multiple disorders such as COVID-19, influenza, and sepsis. Current therapies mainly rely on the inhalation of nitric oxide or injection of pharmaceutical drugs (e.g., glucocorticoids); however, their toxicity, side effects, or administration routes limit their clinical application. In this study, pachypodol (Pac), a hydrophobic flavonol with anti-inflammatory effects, was extracted from Pogostemon cablin Benth and intercalated in liposomes (Pac@liposome, Pac-lipo) to improve its solubility, biodistribution, and bioavailability, aiming at enhanced ALI/ARDS therapy. Nanosized Pac-lipo was confirmed to have stable physical properties, good biodistribution, and reliable biocompatibility. In vitro tests proved that Pac-lipo has anti-inflammatory property and protective effects on endothelial and epithelial barriers in lipopolysaccharide (LPS)-induced macrophages and endothelial cells, respectively. Further, the roles of Pac-lipo were validated on treating LPS-induced ALI in mice. Pac-lipo showed better effects than did Pac alone on relieving ALI phenotypes: It significantly attenuated lung index, improved pulmonary functions, inhibited cytokine expression such as TNF-α, IL-6, IL-1β, and iNOS in lung tissues, alleviated lung injury shown by HE staining, reduced protein content and total cell number in bronchoalveolar lavage fluid, and repaired lung epithelial and vascular endothelial barriers. As regards the underlying mechanisms, RNA sequencing results showed that the effects of the drugs were associated with numerous immune- and inflammation-related signaling pathways. Molecular docking and western blotting demonstrated that Pac-lipo inhibited the activation of the TLR4-MyD88-NF-κB/MAPK signaling pathway. Taken together, for the first time, our new drug (Pac-lipo) ameliorates ALI via inhibition of TLR4-MyD88-NF-κB/MAPK pathway-mediated inflammation and disruption of lung barrier. These findings may provide a promising strategy for ALI treatment in the clinic.