Pre-treatment with notoginsenoside R1 from Panax notoginseng protects against high-altitude-induced pulmonary edema by inhibiting pyroptosis through the NLRP3/caspase-1/GSDMD pathway

Abstract

High-altitude pulmonary edema (HAPE) is a potentially fatal condition that occurs when exposed to high-altitude hypoxia environments. Currently, there is no effective treatment for HAPE, and available interventions focus on providing relief. Notoginsenoside R1 (NGR1), a major active constituent of Panax notoginseng (Burkill) F.H.Chen (sānqī), has demonstrated heart and lung-protective effects under hypobaric hypoxia. However, there is a lack of clarity regarding the precise mechanisms that underlie the protective effects of NGR1 against inflammation. In this study, a rat model of HAPE was developed to assess the effect of NGR1 on this pathology. High-altitude hypoxia corresponding to 6000 m altitude was simulated with a hypobaric chamber. We found that NGR1 dose-dependently alleviated pulmonary oxidative stress damage and inflammatory response, and prevented acid-base balance disruption. In addition, NGR1 restored the expression levels of hypoxia-inducible factor-1 alpha, vascular endothelial growth factor, and aquaporin protein-5, correlated with the development of pulmonary edema induced by hypobaric hypoxia. Furthermore, NGR1 pre-treatment remarkably mitigated NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-induced pyroptosis, and this effect was partially counteracted by the use of an NLRP3 agonist. Thus, NGR1 may exert a lung-protective effect against HAPE by ameliorating hypoxia-induced lung edema, oxidative damage, and inflammation through inhibition of the NLRP3/Caspase-1/ GSDMD signaling pathway.