Effect and mechanism of Bletilla striata polysaccharide on M1 polarization of macrophages
Objective To investigate the effect of Bletilla striata polysaccharide(BSP)on the polarization process of Ml macrophages and its potential mechanisms.Methods THP-1 cells were induced to differentiate into M0 or M1 macrophages and treated with different concentrations(0.001,0.010,0.100,1.000,and 10.000 µg·mL-1)of BSP.The CCK-8 assay was employed to assess cell adhesion and viability following BSP treatment.After selecting an appropriate dose,real-time fluorescence quantitative PCR(qRT-PCR)was used to analyze the expression of M1 macrophage marker genes[Interleukin(IL)-1β,IL-6,tumor necrosis factor-α(TNF-α),inducible nitric oxide synthase(iNOS)]and M2 macrophage marker genes(IL-10,CD206).The release of inflammatory cytokines IL-1β,IL-6,and TNF-α in the supernatant was measured using an enzyme-linked immunosorbent assay,and Western blotting analysis was performed to investigate the effect of BSP on Nuclear factor kappa B(NF-κB)and signal transducer and activator of transcription 1(STAT1)signaling pathways.Results BSP exhibited no significant toxicity to M0 and M1 macrophages within the tested concentration range.BSP significantly downregulated the mRNA expression of M1 macrophage markers(IL-1β,IL-6,TNF-α,and iNOS)and reduced the secretion of these inflammatory cytokines(P＜0.05,0.01,and 0.001).Furthermore,BSP inhibited the protein expression of IL-1β and phosphorylation of p65 and STAT1 proteins.BSP had no significant effect on M0 macrophages.Conclusion BSP effectively suppresses the transformation of M0 macrophages into the M1 phenotype,primarily through the inhibition of NF-κB and STAT1 signaling pathways.
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