Escherichia coli maltose-binding protein activates mouse peritoneal macrophages and induces M1 polarization via TLR2/4 in vivo and in vitro.
Maltose-binding protein (MBP) is a component of the maltose transport system of Escherichia coli. Our previous study found that MBP combined with Bacillus Calmette-Guerin (BCG) increases the percentage of activated macrophages in the spleen and the pinocytic activity of peritoneal macrophages in vivo. However, the effect of MBP alone on macrophages remains unclear. In the present study, the results showed that MBP enhanced LPS-stimulated macrophage activity in vivo. Subsequently, we investigated the regulatory effect of MBP on mouse peritoneal macrophages in vitro and the possible underlying mechanism. The results showed that MBP directly promoted macrophage phagocytic activity and increased the production of NO, IL-1β and IL-6. Notably, macrophage phenotypic analysis showed that MBP significantly increased iNOS, IL-12p70 and CD16/32. In contrast, MBP decreased the secretion of IL-10 and slightly decreased Arg-1 mRNA and CD206 protein expression. These results suggested that MBP activated macrophages and polarized them into M1 macrophages. Further study found that MBP directly bound to macrophages and upregulated TLR2 mRNA expression. This process was accompanied by a clear increase in MyD88 expression and phosphorylation of p38 MAPK and IκB-α, but these effects were largely abrogated by pretreatment with anti-TLR2 or anti-TLR4 antibodies. The effects of MBP on macrophage NO production were also partially inhibited by anti-TLR2 and/or anti-TLR4 antibodies. Furthermore, the effect of MBP on IL-12 and IL-10 secretion was largely influenced by the NF-κB inhibitor PDTC and the p38 MAPK inhibitor SB203580. These results suggest that MBP directly activates macrophages and induces M1 polarization through a process that may involve TLR2 and TLR4.
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China.
Weihua
W
Ni
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China; The First College of Clinical Medical Science, China Three Gorges University, Yichang 443003, China.
Qingyong
Q
Zhang
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China.
Guomu
G
Liu
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China.
Fang
F
Wang
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China.
Hongyan
H
Yuan
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China.
Yingying
Y
Guo
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China.
Xu
X
Zhang
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China.
Fei
F
Xie
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China.
Qiongshu
Q
Li
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China. Electronic address: taiguixiang@163.com.
Guixiang
G
Tai
D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D001119:Arginase / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology*; D058619:Maltose-Binding Proteins / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D009569:Nitric Oxide / Q000378:metabolism; D010587:Phagocytosis; D011392:Proline / Q000031:analogs & derivatives / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D013859:Thiocarbamates / Q000494:pharmacology; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000276:immunology / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors
D019138:Antibodies, Blocking; D015703:Antigens, CD; D016207:Cytokines; D007093:Imidazoles; D058619:Maltose-Binding Proteins; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D011725:Pyridines; D013859:Thiocarbamates; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; C066229:prolinedithiocarbamate; D009569:Nitric Oxide; D011392:Proline; D048051:p38 Mitogen-Activated Protein Kinases; C544448:Arg1 protein, mouse; D001119:Arginase; C093642:SB 203580
Activation; M1 macrophage; Maltose-binding protein, MBP; Toll-like receptor 2, TLR2; Toll-like receptor 4, TLR4