Toll-like receptor 4 mediates the antitumor host response induced by a 55-kilodalton protein isolated from Aeginetia indica L., a parasitic plant.
A 55-kDa protein named AILb-A, isolated from the seed extract of Aeginetia indica L., a parasitic plant, induces a Th1-type T-cell response and elicits a marked antitumor effect in tumor-bearing mice. In the present study, we examined the role of Toll-like receptors (TLRs), which have been implicated in pathogen-induced cell signaling, in AILb-A-induced immune responses. In the luciferase assay using a nuclear factor (NF)-kappaB-dependent reporter plasmid, AILb-A induced NF-kappaB activation in the cells transfected with TLR4, but not with those transfected with the TLR2 gene, in a dose-dependent manner. TLR4-mediated NF-kappaB activation induced by AILb-A but not by lipopolysaccharide (LPS) was also observed under serum-free conditions. In in vitro experiments using human peripheral blood mononuclear cells, AILb-A-induced cytokine production was markedly inhibited by anti-TLR4 but not by anti-CD14 antibody, while LPS-induced, TLR4-mediated cytokine production was inhibited by anti-CD14 as well as anti-TLR4 antibodies. Cytokine production, killer cell activities, maturation of dendritic cells, phosphorylation of mitogen-activated protein kinases, and nuclear translocation of interferon-regulatory factor 3 induced by AILb-A were severely impaired in TLR4-deficient but not TLR2-deficient mice. Transfection of TLR4-deficient mouse-derived macrophages with the TLR4 expression plasmid led AILb-A to induce cytokines. Finally, the antitumor effect of AILb-A was also impaired in TLR4-deficient and TLR4-mutated mice. These findings suggest that TLR4 mediates antitumor immunity induced by the plant-derived protein AILb-A.
Okamoto
Masato
M
Second Department of Oral and Maxillofacial Surgery, The University of Tokushima School of Dentistry, 3-18-15 Kuramoto-cho, Tokushima 7708504, Japan. mokamoto@dent.tokushima-u.ac.jp
Oh-E
Go
G
Oshikawa
Tetsuya
T
Furuichi
Sachiko
S
Tano
Tomoyuki
T
Ahmed
Sharif U
SU
Akashi
Sachiko
S
Miyake
Kensuke
K
Takeuchi
Osamu
O
Akira
Shizuo
S
Himeno
Kunisuke
K
Sato
Mitsunobu
M
Ohkubo
Shinya
S
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D000950:Antigens, Ly / Q000235:genetics / Q000502:physiology; D000954:Antigens, Surface / Q000235:genetics / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000276:immunology / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D003602:Cytotoxicity, Immunologic / Q000187:drug effects / Q000276:immunology / Q000502:physiology; D004268:DNA-Binding Proteins; D003713:Dendritic Cells / Q000187:drug effects / Q000378:metabolism; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D007150:Immunohistochemistry; D007155:Immunologic Factors / Q000276:immunology / Q000502:physiology; D050838:Interferon Regulatory Factor-3; D007371:Interferon-gamma / Q000097:blood; D018664:Interleukin-12 / Q000097:blood / Q000378:metabolism; D020014:K562 Cells; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000276:immunology / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology; D051218:Lymphocyte Antigen 96; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008970:Molecular Weight; D016328:NF-kappa B / Q000378:metabolism; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000276:immunology* / Q000628:therapy; D010457:Peptidoglycan / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014157:Transcription Factors; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000378:metabolism
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000950:Antigens, Ly; D000954:Antigens, Surface; D004268:DNA-Binding Proteins; C494232:IRF3 protein, human; D007155:Immunologic Factors; D050838:Interferon Regulatory Factor-3; C494233:Irf3 protein, mouse; C495377:LY96 protein, human; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; C411728:Ly96 protein, mouse; D051218:Lymphocyte Antigen 96; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D010457:Peptidoglycan; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D018664:Interleukin-12; D007371:Interferon-gamma; D020928:Mitogen-Activated Protein Kinases