Xanthoplanine attenuates macrophage polarization towards M1 and inflammation response via disruption of CrkL-STAT5...

Monocyte infiltration and macrophage polarization are widely considered as pivotal steps for the initiation and progression of atherosclerosis. Previous studies suggested that zanthoxylum piperitum had strong analgesic and anti-inflammatory effects. However, it remains unclear whether zanthoxylum piperitum inhibits inflammation via macrophage function. In the present study, we investigated the effects of xanthoplanine (the total alkaloid extract of zanthoxylum piperitum) on macrophage function. CCK-8 kit was performed to determine cell viability and the preferred concentration of xanthoplanine. We assayed the effects of xanthoplanine on markers of macrophage polarization and inflammation via quantitative PCR and enzyme-linked immunosorbent assay, and measured the production of reactive oxygen species (ROS) by flow cytometry. Immunoblots, co-immunoprecipitation, immunofluorescence and Luciferase activity were performed to investigate the molecular mechanism of STAT signaling pathway in response to xanthoplanine. We found that xanthoplanine (50 and 100 μM) significantly reduced M1 polarization and promoted M2 polarization. The contents of inflammatory cytokines measured by ELISA were markedly decreased in macrophages pretreated with xanthoplanine, compared with those induced by LPS and IFN-γ. In parallel, xanthoplanine alleviated the production of ROS in macrophages induced by LPS and IFN-γ. Moreover, xanthoplanine alleviated STAT5 phosphorylation and blocked STAT5 nuclear translocation without alterations in CrkL expression, subsequently interrupting the interaction between p-STAT5 and CrkL. Likewise, xanthoplanine prominently attenuated the transcription activity of STAT5 induced by LPS and IFN-γ but did not affect the transcription activity of STAT1 and STAT3. Xanthoplanine attenuated M1 phenotypic switch and macrophage inflammation via blocking the formation of CrkL-STAT5 complex.