Background: Polygonum cuspidatum  is a Chinese medicine commonly used to treat phlegm-heat asthma. However, its anti-asthmatic active ingredients and mechanism are still unknown. The aim of this study was to predict the active ingredients and pathways of Polygonum cuspidatum  and to further explore the potential molecular mechanism in asthma by using network pharmacology.
Methods: The active ingredients and their targets related to Polygonum cuspidatum  were seeked out with the TCM systematic pharmacology analysis platform (TCMSP), and the ingredient-target network was constructed. The GeneCards, DrugBank and OMIM databases were used to collect and screen asthma targets, and then the drug-target-disease interaction network was constructed with Cytoscape software. A target protein-protein interaction (PPI) network was constructed using the STRING database to screen key targets. Finally, GO and KEGG analyses were used to identify biological processes and signaling pathways. The anti-asthmatic effects of Polygonum cuspidatum  and its active ingredients were tested in vitro for regulating airway smooth muscle (ASM) cells proliferation and MUC5AC expression, two main symptoms of asthma, by using Real-time PCR, Western blotting, CCK-8 assays and annexin V-FITC staining.
Results: Twelve active ingredients in Polygonum cuspidatum  and 479 related target proteins were screened in the relevant databases. Among these target proteins, 191 genes had been found to be differentially expressed in asthma. PPI network analysis and KEGG pathway enrichment analysis predicted that the Polygonum cuspidatum  could regulate the AKT, MAPK and apoptosis signaling pathways. Consistently, further in vitro experiments demonstrated that Polygonum cuspidatum  and resveratrol (one active ingredient of Polygonum cuspidatum ) were shown to inhibit ASM cells proliferation and promoted apoptosis of ASM cells. Furthermore, Polygonum cuspidatum  and resveratrol inhibited PDGF-induced AKT/mTOR activation in ASM cells. In addition, Polygonum cuspidatum decreased H₂O₂ induced MUC5AC overexpression in airway epithelial NCI-H292 cells.
Conclusion: Polygonum cuspidatum could alleviate the symptoms of asthma including ASM cells proliferation and MUC5AC expression through the mechanisms predicted by network pharmacology, which provides a basis for further understanding of Polygonum cuspidatum  in the treatment of asthma.
Keywords: Polygonum cuspidatum , asthma, ASM cells, MUC5AC, network pharmacology