ABSTRACT
ObjectiveTo explore the mechanism of Buyang Huanwutang in regulating macrophage polarization based on the Toll-like receptor 4 （TLR4） / nuclear factor-κB （NF-κB） / nucleotide-binding oligomerization domain-like receptor 3 （NLRP3） pathway. MethodRAW264.7 macrophages were intervened with lipopolysaccharide （LPS） of different concentrations （0， 1.25， 2.5， 5， 10， 20， 40， and 80 mg·L-1） for 24 hours. Cell Counting Kit-8 （CCK-8） assay was used to determine the cell viability of RAW264.7 macrophages. The optimal concentration was chosen to establish an in vitro inflammation model induced by LPS. Cells were divided into a blank group （20% blank serum）， a model group （20% blank serum + 10 mg·L-1 LPS）， a model control group （20% FBS + 10 mg·L-1 LPS）， low-， medium-， and high-dose （5%， 10%， and 20%） Buyang Huanwutang-containing serum groups， a high-dose （20%） Buyang Huanwutang combined with NLRP3 inhibitor MCC950 （50 μmol·L-1） group， a high-dose （20%） Buyang Huanwutang combined with reactive oxygen species （ROS） inhibitor NAC （10 μmol·L-1） group， and a high-dose （20%） Buyang Huanwutang combined with NF-κB inhibitor PDTC （10 μmol·L-1） group. Enzyme-linked immunosorbent assay （ELISA） was used to detect the expression of interleukin-1β （IL-1β）， interleukin-18 （IL-18）， and tumor necrosis factor-α （TNF-α） in RAW264.7 macrophages. Flow cytometry was employed to measure ROS levels in macrophages. Western blot was used to determine the protein expression of M1-type macrophage-related factors inducible nitric oxide synthase （iNOS） and TNF-α， M2-type macrophage-related factors arginase-1 （Arg-1） and interleukin-10 （IL-10）， as well as the proteins in the TLR4/NF-κB/NLRP3 pathway. ResultCCK-8 results indicated that under 10 mg·L-1 LPS stimulation， RAW264.7 macrophages exhibited the highest cell viability （P<0.01）. Compared with the blank group， the model group showed significantly increased levels of IL-1β， IL-18， and TNF-α （P<0.05，P<0.01）， increased ROS expression （P<0.05，P<0.01）， increased protein expression of M1-type macrophage factors iNOS and TNF-α （P<0.01）， decreased protein expression of M2-type macrophage factors Arg-1 and IL-10 （P<0.05，P<0.01）， and upregulated expression levels of TLR4， myeloid differentiation factor 88 （MyD88）， phosphorylated inhibitor of NF-κB （p-IκB）/NF-κB inhibitor （IκB）， phosphorylated NF-κB （p-NF-κB） p65/NF-κB p65， NLRP3， apoptosis-associated speck-like protein containing a CARD （ASC）， and pro-Caspase-1 （P<0.05， P<0.01）. Compared with the model group， all Buyang Huanwutang-treated groups and inhibitor groups significantly reduced levels of IL-1β， IL-18， and TNF-α （P<0.01）， suppressed the expression of inflammatory factors in RAW264.7 macrophages， decreased cellular ROS expression levels （P<0.01）， downregulated M1-type macrophages iNOS and TNF-α protein expression （P<0.01）， upregulated M2-type macrophages Arg-1 and IL-10 protein expression （P<0.01）， and lowered protein expression levels of TLR4， MyD88， p-IκB/IκB， p-NF-κB p65/NF-κB p65， NLRP3， ASC， and pro-Caspase-1 （P<0.05， P<0.01）. ConclusionBuyang Huanwutang can improve macrophage inflammation， potentially by reducing macrophage ROS levels， inhibiting RAW264.7 macrophage polarization， and downregulating the protein expression levels of the TLR4/NF-κB/NLRP3 pathway.