Mechanism of Zhenqi Granules against the adhesion and invasion of MRSA to human lung epithelial cells
Objective To investigate the inhibitory effect and mechanism of Zhenqi Granules(ZQ)on the adhesion and invasion of Methicillin-resistant Staphylococcus aureus(MRSA)to human lung epithelial cells(BEAS-2B).Method BEAS-2B cells were cultured routinely,and different concentrations of ZQ(7.5,10,12.5 mg/mL)were used to treat the cells.A control group(cells cultured with DMEM only)was also set up.The cell viability was measured using the cell counting kit-8(CCK-8)assay,and the concentration with no significant effect on cell viability was selected as the experimental concentration for ZQ.A portion of the cells was randomly divided into the control group and the ZQ group.The ZQ group was pretreated with the experimental concentration of ZQ before establishing an MRSA infection model in BEAS-2B cells.The adhesion and invasion abilities of MRSA were observed by plate colony counting.The effect of ZQ on MRSA adhesion genes(fnbA,clfA,clfB,icaA,cna,efb,sasX)and BEAS-2B cell tight junction(TJ)protein-coding genes(claudin-1,ZO-1,occludin)was detected by real-time fluorescence quantitative PCR(RT-PCR).Western blotting was used to assess the effect of ZQ on the expression of TJ proteins in BEAS-2B cells.Result Compared with the control group,the 7.5 and 10 mg/mL ZQ groups showed higher cell viability(P<0.01),while there was no significant difference in cell viability in the 12.5 mg/mL group(P>0.05).Therefore,12.5 mg/mL was selected as the experimental concentration for ZQ.Compared with the control group,the ZQ group showed fewer MRSA colonies(P<0.05),lower relative adhesion rate and relative invasion rate(P<0.05),and lower expression levels of MRSA adhesion-related genes fnbA,clfA,clfB,icaA,and cna(P<0.05),while the expression of efb and sasX showed no significant difference(P>0.05).The gene and protein expression levels of TJ proteins claudin-1,ZO-1,and occludin were significantly higher in the ZQ group(P<0.01).Conclusion ZQ can inhibit the adhesion and invasion of MRSA to BEAS-2B cells,which is related to the downregulation of MRSA adhesion genes and the upregulation of TJ protein expression.
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