Endotoxin-induced maturation of MyD88-deficient dendritic cells.
LPS, a major component of the cell wall of Gram-negative bacteria, can induce a variety of biological responses including cytokine production from macrophages, B cell proliferation, and endotoxin shock. All of them were completely abolished in MyD88-deficient mice, indicating the essential role of MyD88 in LPS signaling. However, MyD88-deficient cells still show activation of NF-kappaB and mitogen-activated protein kinase cascades, although the biological significance of this activation is not clear. In this study, we have examined the effects of LPS on dendritic cells (DCs) from wild-type and several mutant mice. LPS-induced cytokine production from DCs was dependent on MyD88. However, LPS could induce functional maturation of MyD88-deficient DCs, including up-regulation of costimulatory molecules and enhancement of APC activity. MyD88-deficient DCs could not mature in response to bacterial DNA, the ligand for Toll-like receptor (TLR)9, indicating that MyD88 is differentially required for TLR family signaling. MyD88-dependent and -independent pathways originate at the intracytoplasmic region of TLR4, because both cytokine induction and functional maturation were abolished in DCs from C3H/HeJ mice carrying the point mutation in the region. Finally, in vivo analysis revealed that MyD88-, but not TLR4-, deficient splenic CD11c(+) DCs could up-regulate their costimulatory molecule expression in response to LPS. Collectively, the present study provides the first evidence that the MyD88-independent pathway downstream of TLR4 can lead to functional DC maturation, which is critical for a link between innate and adaptive immunity.
Kaisho
T
T
Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
Takeuchi
O
O
Kawai
T
T
Hoshino
K
K
Akira
S
S
D048868:Adaptor Proteins, Signal Transducing; D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis; D000943:Antigens, Differentiation / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D051940:B7-2 Antigen; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism; D019013:CD40 Antigens / Q000096:biosynthesis; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002462:Cell Membrane / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000502:physiology; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D029721:Drosophila Proteins; D007275:Injections, Intravenous; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D053594:Myeloid Differentiation Factor 88; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D011971:Receptors, Immunologic; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013045:Species Specificity; D013154:Spleen / Q000166:cytology / Q000276:immunology; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9; D051193:Toll-Like Receptors
D048868:Adaptor Proteins, Signal Transducing; D000276:Adjuvants, Immunologic; D015703:Antigens, CD; D000943:Antigens, Differentiation; D051940:B7-2 Antigen; D019013:CD40 Antigens; C497965:Cd86 protein, mouse; D016207:Cytokines; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C495370:Tlr9 protein, mouse; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9; D051193:Toll-Like Receptors