Endotoxin can induce MyD88-deficient dendritic cells to support T(h)2 cell differentiation.
Toll-like receptor (TLR) signaling activates dendritic cells (DC) to secrete proinflammatory cytokines and up-regulate co-stimulatory molecule expression, thereby linking innate and adaptive immunity. A TLR-associated adapter protein, MyD88, is essential for cytokine production induced by TLR. However, in response to a TLR4 ligand, lipopolysaccharide (LPS), MyD88-deficient (MyD88(-/-)) DC can up-regulate co-stimulatory molecule expression and enhance their T cell stimulatory activity, indicating that the MyD88-independent pathway through TLR4 can induce some features of DC maturation. In this study, we have further characterized function of LPS-stimulated, MyD88(-/-) DC. In response to LPS, wild-type DC could enhance their ability to induce IFN-gamma production in allogeneic mixed lymphocyte reaction (alloMLR). In contrast, in response to LPS, MyD88(-/-) DC augmented their ability to induce IL-4 instead of IFN-gamma in alloMLR. Impaired production of T(h)1-inducing cytokines in MyD88(-/-) DC cannot fully account for their increased T(h)2 cell-supporting ability, because absence of T(h)1-inducing cytokines in DC caused impairment of IFN-gamma, but did not lead to augmentation of IL-4 production in alloMLR. In vivo experiments with adjuvants also revealed T(h)2-skewed immune responses in MyD88(-/-) mice. These results demonstrate that the MyD88-independent pathway through TLR4 can confer on DC the ability to support T(h)2 immune responses.
Kaisho
Tsuneyasu
T
Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.
Hoshino
Katsuaki
K
Iwabe
Tomio
T
Takeuchi
Osamu
O
Yasui
Teruhito
T
Akira
Shizuo
S
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes; D002454:Cell Differentiation; D002455:Cell Division; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000276:immunology*; D029721:Drosophila Proteins; D007371:Interferon-gamma / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000235:genetics; D011971:Receptors, Immunologic / Q000172:deficiency* / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction; D018418:Th2 Cells / Q000166:cytology*; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors
D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D029721:Drosophila Proteins; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D015847:Interleukin-4; D007371:Interferon-gamma