San-Wei-Du-Juan formula ameliorates hypoxic lung injury by regulating the MAPK signaling pathway.

San-Wei-Du-Juan (SWDJ), a classic Tibetan herbal formulation composed of Rhododendron anthopogonoides Maxim., Elettaria cardamomum (L.) Maton, and Alpinia officinarum Hance., has been traditionally used for its anti-hypoxic, anti-inflammatory, and antioxidant activities. However, its protective effects and mechanisms against hypoxic lung injury remain unclear. This study aimed to evaluate the protective effects of SWDJ against hypobaric hypoxia-induced lung injury and to elucidate its underlying molecular mechanisms, with a particular focus on the MAPK signaling pathway and mitochondrial apotosis. A hypobaric hypoxia-induced lung injury mouse model (simulated 6000 m altitude for 24 h) and a hypoxic RLE-6TN cell model were established. SWDJ was administered orally at doses of 2.275 g/kg and 11.375 g/kg for 14 days. Pulmonary function, histopathology, hematological parameters, oxidative stress markers (SOD, MDA, ROS), inflammatory cytokines (TNF-α, IL-1β, IL-6), apoptosis-related proteins (Bax, Bcl-2, Caspase-3) and MAPK pathway proteins (p-JNK, p-p38) were assessed. Network pharmacology and transcriptomic sequencing were also employed. SWDJ significantly attenuated hypobaric hypoxia-induced lung injury, as evidenced by a 32.5% reduction in lung wet/dry weight, restored alveolar architecture, and improved pulmonary function parameters including a 41.2% decrease in respiratory frequency and a 38.7% reduction in minute ventilation compared to the model group. Hematological analysis showed that SWDJ-H reduced RBC count by 22.3%, HGB by 19.8%, and HCT by 21.5%, effectively reversing hypoxia-induced polycythemia. Mechanistically, SWDJ suppressed oxidative stress by increasing SOD activity by 2.4-fold and reducing MDA levels by 58.6%, inhibited inflammatory cytokine expression (TNF-α, IL-1β and IL-6), and reduced apoptosis by increasing the Bcl-2/Bax ratio by 3.1-fold and decreasing caspase-3 expression by 52.7%. Furthermore, SWDJ downregulated HIF-1α expression and inhibited the phosphorylation of JNK and p38 MAPK. This study is the first to systematically demonstrate that SWDJ protects against hypobaric hypoxia-induced lung injury through coordinated inhibition of the MAPK (JNK/p38) pathway, highlighting its potential as a therapeutic agent for high-altitude hypoxic pulmonary diseases.