1. Differential requirements of MyD88 and TRIF pathways in TLR4-mediated immune responses in murine B cells
- Author
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Yasuharu Watanabe, Tsutomu Yanagibashi, Kiyoshi Takatsu, Masashi Ikutani, Yoshikatsu Hirai, and Yoshinori Nagai
- Subjects
LPS ,Immunology ,chemical and pharmacologic phenomena ,Biology ,Mice ,Immune system ,Interferon ,TLR ,medicine ,Activation-induced (cytidine) deaminase ,Animals ,Immunology and Allergy ,CSR ,TRIF ,Interleukin 4 ,Mice, Knockout ,Innate immunity ,CD86 ,B-Lymphocytes ,Innate immune system ,MyD88 ,Molecular biology ,Toll-Like Receptor 4 ,Adaptor Proteins, Vesicular Transport ,Immunoglobulin class switching ,Immunoglobulin G ,Antibody Formation ,Myeloid Differentiation Factor 88 ,biology.protein ,Signal Transduction ,medicine.drug - Abstract
LPS stimulates the TLR4/Myeloid differentiation protein-2 (MD-2) complex and promotes a variety of immune responses in B cells. TLR4 has two main signaling pathways, MyD88 and Toll/IL-1R (TIR)-domain-containing adaptor-inducing interferon-β (TRIF) pathways, but relatively few studies have examined these pathways in B cells. In this study, we investigated MyD88- or TRIF-dependent LPS responses in B cells by utilizing their knockout mice. Compared with wild-type (WT) B cells, MyD88(-/-) B cells were markedly impaired in up-regulation of CD86 and proliferation induced by lipid A moiety of LPS. TRIF(-/-) B cells were also impaired in these responses compared with WT B cells, but showed better responses than MyD88(-/-) B cells. Regarding class switch recombination (CSR) elicited by lipid A plus IL-4, MyD88(-/-) B cells showed similar patterns of CSR to WT B cells. However, TRIF(-/-) B cells showed the impaired in the CSR. Compared with WT and MyD88(-/-) B cells, TRIF(-/-) B cells exhibited reduced cell division, fewer IgG1(+) cells per division, and decreased activation-induced cytidine deaminase (Aicda) mRNA expression in response to lipid A plus IL-4. Finally, IgG1 production to trinitrophenyl (TNP)-LPS immunization was impaired in TRIF(-/-) mice, while MyD88(-/-) mice exhibited increased IgG1 production. Thus, MyD88 and TRIF pathways differently regulate TLR4-induced immune responses in B cells.
- Published
- 2015
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