Mycoplasma pneumoniae MsrB Inhibits the Secretion of Proinflammatory Cytokines by Lipid-Associated Membrane Proteins via the MAPK/NF-κB Pathway

MENG Yan¹, LI Tingting¹, HE Guiting¹, WANG Zhimin², XIAO Zhiqin², TIAN Wei^3
*, ZHU Cuiming^1
*

( ¹ Institute of Pathogenic Biology, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, Hengyang Medical College, University of South China, Hengyang 421001, China; ² Medical Laboratory Technology, Chuanshan College, University of South China, Hengyang 421001, China; ³ Blood Transfusion Department, Affiliated Nanhua Hospital, Hengyang Medical College, University of South China, Hengyang 421001, China)

Abstract:

MsrB (methionine sulfoxide reductase) is an essential redox protein in prokaryotic and eukaryotic cells. This study aimed to investigate the regulation and signaling pathway of MsrB on the secretion of the proinflammatory cytokines TNF-α (tumor necrosis factor-alpha) and IL-1β (interleukin 1β) in THP-1 cells (human myeloid 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 purified, 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 translocation of NF-κB was tested by indirect immunofluorescence. The secretion of TNF-α and IL-1β was analyzed using 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 rMsrB 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.

CSTR: 32200.14.cjcb.2024.02.0006