Mycoplasma pneumoniae MsrB Inhibits the Secretion of Proinflammatory Cytokines by Lipid-Associated Membrane Proteins via the MAPK/NF-κB Pathway
MsrB(methionine sulfoxide reductase)is an essential redox protein in prokaryotic and eukary-otic cells.This study aimed to investigate the regulation and signaling pathway of MsrB on the secretion of the pro-inflammatory cytokines TNF-α(tumor necrosis factor-alpha)and IL-1β(interleukin 1β)in THP-1 cells(human my-eloid leukemia monocytes)which were stimulated with LAMPs(lipid-associated membrane proteins)derived from Mp(Mycoplasma pneumoniae),so as to further understand the immune evade of Mp.In this study,pET28a(+)-msrB recombinant plasmid was constructed,the rMsrB(recombinant MsrB protein)was expressed,identified,and puri-fied,and polyclonal antibody was prepared.The expression of MsrB,TLR1,TLR2,TLR6,and MyD88,the total and phosphorylated proteins of NF-κB p65,P38,ERK,and JNK were detected by Western blot.The nuclear trans-location of NF-κB was tested by indirect immunofluorescence.The secretion of TNF-α and IL-1β was analyzed us-ing ELISA.Data showed that MsrB was expressed in the cytoplasm and cytosol of Mp.Mp MsrB could reduce the synthesis of TNF-α and IL-1β in LAMPs-stimulated THP-1,and decrease the expression of TLR2,MyD88,p-ERK,p-JNK,p-p38,and p-p65.Moreover,NF-κB nuclear translocation was inhibited by Mp MsrB in LAMPs-stimulated THP-1 cells.Moreover,inhibiting NF-κB,P38,ERK,and JNK further reduced TNF-α and IL-1β production by rM-srB in LAMPs-stimulated THP-1 cells.In summary,Mp MsrB protein inhibits TNF-α and IL-1β secretion via the TLR2/MyD88/MAPK/NF-κB signaling pathway.
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