Quercetin, a key active ingredient of Jianpi Zishen Xiehuo Formula, suppresses M1 macrophage polarization and platelet phagocytosis by inhibiting STAT3 activation based on network pharmacology

Primary immune thrombocytopenia (ITP) is an autoimmune hemorrhagic disease, and abnormal M1 macrophage polarization participates in the pathogenesis of ITP. Jianpi Zishen Xiehuo (JZX) Formula has a good therapeutic effect on ITP. However, its key active ingredients and molecular mechanisms remain unclear. In this study, we explored the key active ingredients and potential targets of JZX in treating ITP using network pharmacology combined with in vitro experimental verification. A total of 157 active ingredients of JZX were identified from public databases, and quercetin was the most important one. One hundred sixty-five intersection targets of active ingredients in JZX, ITP, and macrophage polarization were obtained by Venn diagram. The top three potential targets were signal transducer and activator of transcription 3 (STAT3), protein kinase B (PKB/AKT) 1, and c-JUN through protein-protein interaction analysis. Molecular docking showed that quercetin had strong binding affinities with them all. In vitro experiment, CD16+ monocytes increased in ITP patients compared with healthy controls, which indicated a M1/M2 polarization imbalance in ITP. The expression levels of M1 polarization markers, CD86, CD80, and inducible nitric oxide synthase (iNOS), M1 polarization-associated cytokines, tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6), and antibody-opsonized platelet phagocytosis significantly increased in THP-1 macrophages stimulated with lipopolysaccharide (LPS). Quercetin markedly inhibited the expressions of M1 markers, decreased the levels of TNF-alpha and IL-6, and down-regulated the phosphorylated STAT3 (p-STAT3) protein, which confirmed the prediction by network pharmacology and molecular docking. Importantly, quercetin significantly reduced the phagocytosis of antibody opsonised platelet. In conclusion, quercetin suppressed platelet phagocytosis in M1 macrophages via its anti-inflammatory effects and may serve as a potential drug for the treatment of ITP. Quercetin could be a key ingredient for JZX against ITP.