Protective effects of harringtonine on lipopolysaccharide-induced acute lung injury via a novel intratracheal instillation method.

Acute lung injury (ALI), an inflammatory disease with high mortality, urgently requires novel therapeutic interventions. Harringtonine (HT) is a natural alkaloid with anti-inflammatory and antiviral properties. However, its efficacy in mitigating LPS-induced ALI remains unclear. This study systematically optimized the administration strategies of HT, to enhance therapeutic outcomes. Using high performance liquid chromatography-fluorescence detection (HPLC-FLD), we observed rapid HT degradation in SD rat plasma compared to other species. By exploring the tissue distribution of HT in SD rats following systemic (Intravenous/oral) or local (intranasal/aerosol/intratracheal) administration, intratracheal instillation achieved the highest lung concentrations of HT, establishing it as the optimal therapeutic approach for lung-targeted therapy. Furthermore, the anti-inflammatory effects of HT were investigated in lipopolysaccharide (LPS)-induced ALI mouse model and RAW 264.7 cells. HT significantly alleviated lung pathological alterations and edema, as demonstrated by hematoxylin-eosin staining, Masson staining, and the measurement of lung wet-to-dry (W/D) ratios and total protein levels. Concurrently, HT attenuated inflammatory responses by inhibiting inflammatory infiltration and cytokines release, as evidenced by decreased F4/80 expression, myeloperoxidase activity, and decreased levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and nitric oxide (NO). Moreover, HT mitigated oxidative stress by reducing reactive oxygen species (ROS), and restored redox homeostasis by increasing superoxide dismutase (SOD) and glutathione (GSH) levels while suppressing malondialdehyde (MDA) level. Collectively, HT demonstrated protective effects against LPS-induced ALI in vivo and in vitro, which was closely associated with the attenuation of inflammation and oxidative stress, suggesting its potential as a novel therapeutic candidate for ALI.