OBJECTIVE To investigate the therapeutic mechanism of Sanhan Huashi Formula (SHF) in treating respiratory syncytial virus (RSV) pneumonia through a combination of network pharmacology, molecular docking, and animal experiments.

METHODS An in vivo prototype component library of SHF was constructed through literature retrieval. RSV-related disease targets were obtained from multiple disease databases and differentially expressed genes from GEO datasets. A Protein-Protein Interaction (PPI) network and a "component-target" network were established to screen for core targets and components. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed using the Metascape platform. Molecular docking and molecular dynamics simulations were conducted to validate the core components and targets. Fifty-four Balb/c mice were randomly divided into a blank control group, a model group, a ribavirin group, and low-, medium-, and high-dose SHF groups. An RSV pneumonia mouse model was established through nasal instillation. The blank group and the model group were given ultrapure water, while the mice in the remaining groups were administered corresponding medicinal solutions via oral gavage, continuously for three days. HE staining and inflammation scoring were used to observe pathological changes in lung inflammation. RT-qPCR was employed to detect the mRNA expression levels of IL-1β, ZO-1, Claudin-5, and PI3K. Western blot was used to examine the proteins expression of PI3K, p-PI3K in lung tissue.

RESULTS A total of 29 effective active components and 541 drug-related targets were identified. Topological analysis screened five core components: magnolignan C, magnolignan A, magnoflorine, honokiol, and magnolol, along with two core targets: PIK3CB and PIK3CD. KEGG enrichment analysis showed significant enrichment of the PI3K-Akt signaling pathway. Molecular docking and molecular dynamics simulation analysis showed that the five core components (magnolignan C, magnolignan A, magnoflorine, honokiol, and magnolol) all had high binding energies (< -7.0 kcal·mol^-1) with the two core targets PIK3CB and PIK3CD, indicating stable binding between the core targets and components. Animal experiments demonstrated that SHF significantly improved the pathological condition of lung tissue inflammation in mice, reduced the mRNA expression levels of IL-1β and PI3K (P < 0.01), increased the mRNA expression levels of ZO-1 and Claudin-5 (P < 0.05, P < 0.01), and decreased the ratios of p-PI3K/PI3K (P < 0.01).

CONCLUSION SHF can inhibit the secretion of inflammatory factors, enhance the alveolar barrier, and suppress the activation of the PI3K-Akt signaling pathway, effectively improving RSV-induced pathological damage to lung inflammation.