151
|
Rosenthal LA, Mikus LD, Tuffaha A, Mosser AG, Sorkness RL, Lemanske RF. Attenuated innate mechanisms of interferon-gamma production in rats susceptible to postviral airway dysfunction. Am J Respir Cell Mol Biol 2003; 30:702-9. [PMID: 14592927 DOI: 10.1165/rcmb.2003-0181oc] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
After Sendai virus (SeV)-induced bronchiolitis as weanlings, BN, but not F344, rats develop a postbronchiolitis asthma-like phenotype, which can be prevented by supplemental interferon (IFN)-gamma treatment. We have shown that splenocytes from BN weanlings, compared with those from F344 weanlings, have a markedly reduced capacity for IFN-gamma production. We hypothesized that SeV-induced IFN-gamma production occurs via innate mechanisms that are attenuated in BN weanlings. Therefore, we investigated potential mechanisms of SeV-induced IFN-gamma production in BN and F344 weanlings. SeV-stimulated splenocytes secreted the IFN-gamma-inducing cytokines, interleukin (IL)-12 and IL-18. BN splenocytes produced significantly less IL-12 (P = 0.001) and IL-18 (P < 0.001) than did F344 splenocytes. Depletion studies demonstrated that natural killer cells were the primary source of SeV-induced IFN-gamma production. Anti-IL-12 antibody, IL-12 p40 homodimer, and IL-18 binding protein each inhibited SeV-induced IFN-gamma production by 82-94%, and the combination of IL-12 p40 homodimer and IL-18 binding protein abolished SeV-induced IFN-gamma production, demonstrating synergism between IL-12 and IL-18. Therefore, SeV-induced IFN-gamma production occurred via innate IL-12-, IL-18-, and natural killer cell-dependent mechanisms, which were attenuated in BN weanlings. Attenuation of innate IFN-gamma-producing responses to SeV in BN weanlings may be a critical factor in their susceptibility to postbronchiolitis chronic airway dysfunction.
Collapse
Affiliation(s)
- Louis A Rosenthal
- Morris Institute for Respiratory Research, University of Wisconsin Medical School, Madison, WI 53792, USA.
| | | | | | | | | | | |
Collapse
|
152
|
Lee JY, Ye J, Gao Z, Youn HS, Lee WH, Zhao L, Sizemore N, Hwang DH. Reciprocal modulation of Toll-like receptor-4 signaling pathways involving MyD88 and phosphatidylinositol 3-kinase/AKT by saturated and polyunsaturated fatty acids. J Biol Chem 2003; 278:37041-51. [PMID: 12865424 DOI: 10.1074/jbc.m305213200] [Citation(s) in RCA: 394] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Toll-like receptor-4 (TLR4) can be activated by nonbacterial agonists, including saturated fatty acids. However, downstream signaling pathways activated by nonbacterial agonists are not known. Thus, we determined the downstream signaling pathways derived from saturated fatty acid-induced TLR4 activation. Saturated fatty acid (lauric acid)-induced NFkappaB activation was inhibited by a dominant-negative mutant of TLR4, MyD88, IRAK-1, TRAF6, or IkappaBalpha in macrophages (RAW264.7) and 293T cells transfected with TLR4 and MD2. Lauric acid induced the transient phosphorylation of AKT. LY294002, dominant-negative (DN) phosphatidylinositol 3-kinase (PI3K), or AKT(DN) inhibited NFkappaB activation, p65 transactivation, and cyclooxygenase-2 (COX-2) expression induced by lauric acid or constitutively active (CA) TLR4. AKT(DN) blocked MyD88-induced NFkappaB activation, suggesting that AKT is a MyD88-dependent downstream signaling component of TLR4. AKT(CA) was sufficient to induce NFkappaB activation and COX-2 expression. These results demonstrate that NFkappaB activation and COX-2 expression induced by lauric acid are at least partly mediated through the TLR4/PI3K/AKT signaling pathway. In contrast, docosahexaenoic acid (DHA) inhibited the phosphorylation of AKT induced by lipopolysaccharide or lauric acid. DHA also suppressed NFkappaB activation induced by TLR4(CA), but not MyD88(CA) or AKT(CA), suggesting that the molecular targets of DHA are signaling components upstream of MyD88 and AKT. Together, these results suggest that saturated and polyunsaturated fatty acids reciprocally modulate the activation of TLR4 and its downstream signaling pathways involving MyD88/IRAK/TRAF6 and PI3K/AKT and further suggest the possibility that TLR4-mediated target gene expression and cellular responses are also differentially modulated by saturated and unsaturated fatty acids.
Collapse
Affiliation(s)
- Joo Y Lee
- Western Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Davis, California 95616, USA
| | | | | | | | | | | | | | | |
Collapse
|
153
|
Manigold T, Böcker U, Chen J, Gundt J, Traber P, Singer MV, Rossol S. Hepatitis B core antigen is a potent inductor of interleukin-18 in peripheral blood mononuclear cells of healthy controls and patients with hepatitis B infection. J Med Virol 2003; 71:31-40. [PMID: 12858406 DOI: 10.1002/jmv.10445] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Clearance of hepatitis B virus infection (HBV) infection implies a polyclonal vigorous T-helper 1 (Th1) and cytotoxic T-lymphocyte (CTL) response. Interleukin-18 (IL-18), a monokine that shares functional abilities with IL-12, is a potent inductor of interferon-gamma (IFN-gamma) by Th1 and natural killer (NK) cells. However, the role and regulation in HBV infection of IFN-gamma have not been defined. This study therefore sought to determine hepatitis B core antigen (HBcAg)-mediated regulation of IL-18 production in peripheral blood mononuclear cells (PBMCs) from healthy controls (HC) and patients with chronic hepatitis B (CHB) or acute hepatitis B (AHB); 31 HC, 27 patients with CHB and 8 patients with AHB infection were included in the study. HBcAg-mediated induction of IL-18 was determined by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and specific enzyme-linked immunosorbent assay (ELISA). HBcAg induced IL-18 gene transcription and dose-dependent secretion of mature IL-18 protein in HC, CHB, and AHB. HBcAg-dependent IL-18 levels were abrogated by inhibition of Caspase-1, but not by blockade of CD40-CD154 interaction. Serum levels of IFN-gamma correlated inversely with viremia in patients with CHB (rho = - 0.54, P < 0.05), but not with serum levels of IL-12 or IL-18. Interestingly, in PBMCs of HBeAg-negative patients, HBcAg induced significantly higher amounts of IL-18 than in those of HBeAg-positive patients. A variant, lacking the histone-like arginine-rich domain, did not induce IL-18 in either HC or CHB in vitro. Taken together, these results indicate that HBcAg induces IL-18 secretion by induction of Caspase-1. Differential regulation in HBeAg-negative and positive patients suggests an important role of IL-18 in CHB infection.
Collapse
Affiliation(s)
- Tobias Manigold
- Department of Medicine II, Gastroenterology/Hepatology/Infectious Diseases, University Hospital Mannheim, Mannheim, Germany.
| | | | | | | | | | | | | |
Collapse
|
154
|
Abstract
The innate immune system in drosophila and mammals senses the invasion of microorganisms using the family of Toll receptors, stimulation of which initiates a range of host defense mechanisms. In drosophila antimicrobial responses rely on two signaling pathways: the Toll pathway and the IMD pathway. In mammals there are at least 10 members of the Toll-like receptor (TLR) family that recognize specific components conserved among microorganisms. Activation of the TLRs leads not only to the induction of inflammatory responses but also to the development of antigen-specific adaptive immunity. The TLR-induced inflammatory response is dependent on a common signaling pathway that is mediated by the adaptor molecule MyD88. However, there is evidence for additional pathways that mediate TLR ligand-specific biological responses.
Collapse
Affiliation(s)
- Kiyoshi Takeda
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Suita Osaka 565-0871, Japan.
| | | | | |
Collapse
|
155
|
Way SS, Kollmann TR, Hajjar AM, Wilson CB. Cutting edge: protective cell-mediated immunity to Listeria monocytogenes in the absence of myeloid differentiation factor 88. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:533-7. [PMID: 12847214 DOI: 10.4049/jimmunol.171.2.533] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In addition to their role in triggering innate immune responses, Toll-like receptors are proposed to play a key role in linking the innate and adaptive arms of the immune response. The majority of cellular responses downstream of Toll-like receptors are mediated through the adapter molecule myeloid differentiation factor 88 (MyD88), and mice with a targeted deletion of MyD88 are highly susceptible to bacterial infections, including primary infection with Listeria monocytogenes (LM). In contrast, herein we demonstrate that MyD88-deficient mice have only a modest impairment in their LM-specific CD4 T cell response, and no impairment in their CD8 T cell response following infection with ActA-deficient LM. Furthermore, CD8 T cells from immunized MyD88-deficient mice protected naive recipient mice following adoptive splenocyte transfer, and immunized MyD88-deficient mice were protected from infection with wild-type LM. These results indicate that adaptive immune responses can be generated and provide protective immunity in the absence of MyD88.
Collapse
MESH Headings
- Adaptor Proteins, Signal Transducing
- Adoptive Transfer
- Animals
- Antigens, Differentiation/genetics
- Antigens, Differentiation/physiology
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/microbiology
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/microbiology
- Dose-Response Relationship, Immunologic
- Epitopes, T-Lymphocyte/immunology
- Genetic Predisposition to Disease
- Immunity, Cellular/genetics
- Immunity, Innate/genetics
- Listeria monocytogenes/genetics
- Listeria monocytogenes/immunology
- Listeriosis/genetics
- Listeriosis/immunology
- Listeriosis/microbiology
- Lymphocyte Activation/genetics
- Lymphocyte Activation/immunology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Myeloid Differentiation Factor 88
- Receptors, Immunologic/deficiency
- Receptors, Immunologic/genetics
- Receptors, Immunologic/physiology
- Spleen/cytology
- Spleen/immunology
- Spleen/transplantation
Collapse
Affiliation(s)
- Sing Sing Way
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98195, USA
| | | | | | | |
Collapse
|
156
|
Abstract
Cathepsin E is an intracellular aspartic proteinase expressed predominantly in immune cells and skin. We show that cathepsin E-deficient mice spontaneously develop atopic dermatitis (AD)-like skin lesions comparable to human AD when kept under conventional circumstances, but not under specific pathogen-free conditions. These mice displayed AD-associated phenotypes including eosinophilia; increased serum IgE, IL-18, and IL-1beta; and enhanced production of Th2 cytokines. Cathepsin E deficiency also resulted in greater decrease of the rate of degradation for serum IL-18 and IL-1beta. Interestingly, cathepsin E levels in blood cells were significantly decreased in AD patients and the AD model NC/Nga mice compared to healthy donors and the control mice, respectively. Our results indicate that deficiency or defective production of cathepsin E strongly induces AD in humans and mice, probably due to the systemic accumulation of IL-18 and IL-1beta, leading to stimulation of Th2 responses, and that cathepsin E-deficient mice are a newly discovered model to analyze pathologic mechanisms of human AD.
Collapse
Affiliation(s)
- Takayuki Tsukuba
- Department of Pharmacology, Graduate School of Dental Science, Kyushu University, Fukuoka, Japan.
| | | |
Collapse
|
157
|
Van Amersfoort ES, Van Berkel TJC, Kuiper J. Receptors, mediators, and mechanisms involved in bacterial sepsis and septic shock. Clin Microbiol Rev 2003; 16:379-414. [PMID: 12857774 PMCID: PMC164216 DOI: 10.1128/cmr.16.3.379-414.2003] [Citation(s) in RCA: 500] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Bacterial sepsis and septic shock result from the overproduction of inflammatory mediators as a consequence of the interaction of the immune system with bacteria and bacterial wall constituents in the body. Bacterial cell wall constituents such as lipopolysaccharide, peptidoglycans, and lipoteichoic acid are particularly responsible for the deleterious effects of bacteria. These constituents interact in the body with a large number of proteins and receptors, and this interaction determines the eventual inflammatory effect of the compounds. Within the circulation bacterial constituents interact with proteins such as plasma lipoproteins and lipopolysaccharide binding protein. The interaction of the bacterial constituents with receptors on the surface of mononuclear cells is mainly responsible for the induction of proinflammatory mediators by the bacterial constituents. The role of individual receptors such as the toll-like receptors and CD14 in the induction of proinflammatory cytokines and adhesion molecules is discussed in detail. In addition, the roles of a number of other receptors that bind bacterial compounds such as scavenger receptors and their modulating role in inflammation are described. Finally, the therapies for the treatment of bacterial sepsis and septic shock are discussed in relation to the action of the aforementioned receptors and proteins.
Collapse
Affiliation(s)
- Edwin S Van Amersfoort
- Division of Biopharmaceutics, Leiden/Amsterdam Center of Drug Research, Leiden University, Leiden, The Netherlands
| | | | | |
Collapse
|
158
|
Akira S, Hoshino K. Myeloid differentiation factor 88-dependent and -independent pathways in toll-like receptor signaling. J Infect Dis 2003; 187 Suppl 2:S356-63. [PMID: 12792852 DOI: 10.1086/374749] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Toll-like receptors (TLRs) play an essential role in the detection of invading pathogens in the body. Individual TLRs recognize distinct components derived from pathogens, which is followed by cytokine production. The TLR family harbors extracellular leucine-rich repeat domains and a cytoplasmic domain that is homologous to that of the interleukin (IL)-1 receptor (IL-1R) family. After stimulation, TLR recruits IL-1R-associated kinase via adaptor myeloid differentiation factor 88 (MyD88) and induces activation of NF-kappaB and mitogen-activated protein kinases. Cytokine production in response to each TLR ligand is completely abrogated in MyD88-deficient cells, which indicates that MyD88 is an essential shared signaling molecule in the IL-1R/Toll family. The TLR4 signal has an MyD88-independent pathway that is involved in induction of type I interferons (IFNs) and IFN-inducible genes via IFN regulatory factor-3 activation. A recently identified adaptor molecule, Toll-IL receptor domain-containing adaptor protein/MyD88 adaptor-like, may participate in the MyD88-independent pathway.
Collapse
Affiliation(s)
- Shizuo Akira
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, and SORST of Japan Science and Technology, Osaka, Japan.
| | | |
Collapse
|
159
|
Abstract
Toll receptors in insects, mammals and plants are key players that sense the invasion of pathogens. Toll-like receptors (TLRs) in mammals have been established to detect specific components of bacterial and fungal pathogens. Furthermore, recent evidence indicates that TLRs are involved in the recognition of viral invasion. Signalling pathways via TLRs originate from the conserved Toll/IL-1 receptor (TIR) domain. The TIR domain-containing MyD88 acts as a common adaptor that induces inflammatory cytokines; however, there exists a MyD88-independent pathway that induces type I IFNs in TLR4 and TLR3 signalling. Another TIR domain-containing adaptor, TIRAP/Mal has recently been shown to mediate the MyD88-dependent activation in the TLR4 and TLR2 signalling pathway. Thus, individual TLRs may have their own signalling systems that characterize their specific activities.
Collapse
Affiliation(s)
- Kiyoshi Takeda
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, and SORST of Japan Science and Technology Corporation, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | | |
Collapse
|
160
|
Abstract
Interleukin-18 (IL-18), a recently described member of the IL-1 cytokine superfamily, is now recognized as an important regulator of innate and acquired immune responses. IL-18 is expressed at sites of chronic inflammation, in autoimmune diseases, in a variety of cancers, and in the context of numerous infectious diseases. This short review will describe the basic biology of IL-18 and thereafter address its potential effector and regulatory role in several human disease states including autoimmunity and infection. IL-18, previously known as interferon-gamma (IFN-gamma)-inducing factor, was identified as an endotoxin-induced serum factor that stimulated IFN-gamma production by murine splenocytes [(1) ]. IL-18 was cloned from a murine liver cell cDNA library generated from animals primed with heat-killed Propionibacterium acnes and subsequently challenged with lipopolysaccharide [(2) ]. Nucleotide sequencing of murine IL-18 predicted a precursor polypeptide of 192 amino acids lacking a conventional signal peptide and a mature protein of 157 amino acids. Subsequent cloning of human IL-18 cDNA revealed 65% homology with murine IL-18 [(3) ] and showed that both contain an unusual leader sequence consisting of 35 amino acids at their N terminus.
Collapse
Affiliation(s)
- J Alastair Gracie
- Centre for Rheumatic Diseases, University of Glasgow, 10 Alexandra Parade, Glasgow G31 2ER, Scotland, UK
| | | | | |
Collapse
|
161
|
Abstract
Myeloid differentiation factor 88 (MyD88) is an adaptor molecule composed of an N-terminal death domain and a C-terminal Toll/interleukin (IL)-1R homology domain. Ligand binding to Toll-like receptor (TLR)/IL-1R family members results in the association of MyD88 to the cytoplasmic tail of receptors; this then initiates the signaling cascade that leads to the activation of nuclear factor-kappa B and mitogen-activated protein kinases. Analysis of MyD88-deficient mice revealed its essential role in TLR/IL-1R signaling as well as in both the innate and the adaptive immune response.
Collapse
Affiliation(s)
- O Takeuchi
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | | |
Collapse
|
162
|
Ohnishi H, Kato Z, Watanabe M, Fukutomi O, Inoue R, Teramoto T, Kondo N. Interleukin-18 is associated with the severity of atopic dermatitis. Allergol Int 2003. [DOI: 10.1046/j.1440-1592.2003.00290.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
163
|
Abstract
This has led to the identification of several important roles for Toll receptors in mammals. This unit discusses mammalian Toll receptors (TLR1-10) that have an essential role in the innate immune recognition of microorganisms. Also discussed are TLR-mediated signaling pathways and antibodies that are available to detect specific TLRs.
Collapse
Affiliation(s)
- Kiyoshi Takeda
- Osaka University and Japan Science and Technology Corporation, Osaka, Japan
| | - Shizuo Akira
- Osaka University and Japan Science and Technology Corporation, Osaka, Japan
| |
Collapse
|
164
|
Rouabhia M, Deslauriers N. Production and characterization of an in vitro engineered human oral mucosa. Biochem Cell Biol 2002; 80:189-95. [PMID: 11989714 DOI: 10.1139/o01-237] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of epithelial cells in oral pathologies is poorly understood. Until now, most studies have used normal or transformed epithelial cell monolayers, a system that largely bypasses oral mucosal complexity. To overcome these limitations, an engineered human oral mucosa (EHOM) model has been produced and characterized. Following histological and immunohistochemical analyses, EHOM showed well-organized and stratified tissues in which epithelial cells expressed proliferating keratins such as Ki-67, K14, and K19 and also differentiating keratin (K10). In this model, epithelial cells interacted with fibroblasts in the lamina propria by secreting basement membrane proteins (laminins) and by expressing integrins (beta1 and alpha2beta1). Cytokine analyses using cultured supernatants showed that cells in EHOM were able to secrete interleukins (IL) including IL-1beta and IL-8 and tumor necrosis factor alpha (TNF-alpha). Finally, cells in this engineered model were able to secrete different metalloproteinases such as gelatinase-A and gelatinase-B. In conclusion, using tissue engineering technology, we produced well-organized EHOM tissues. It is anticipated that this model will be useful for examining mechanisms involved in oral diseases under controlled conditions by modeling the interactions between mucosa and microorganisms in the oral cavity.
Collapse
Affiliation(s)
- Mahmoud Rouabhia
- Faculté de médecine dentaire, Université Laval, Quebec, QC, Canada.
| | | |
Collapse
|
165
|
Edelson BT, Unanue ER. MyD88-dependent but Toll-like receptor 2-independent innate immunity to Listeria: no role for either in macrophage listericidal activity. THE JOURNAL OF IMMUNOLOGY 2002; 169:3869-75. [PMID: 12244184 DOI: 10.4049/jimmunol.169.7.3869] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We have assessed the requirements for Toll-like receptor (TLR) signaling in vivo during early infection with Listeria monocytogenes. Mice deficient for TLR2, a receptor required for the recognition of Gram-positive peptidoglycan, showed equivalent Listeria resistance to wild-type mice. However, mice deficient for MyD88, an adaptor molecule used by all TLRs, showed profound susceptibility with 3-4 logs greater Listeria burden and severe spleen and liver pathology at day 3 postinfection. Listeria-infected MyD88-deficient mice also showed markedly diminished IFN-gamma, TNF-alpha, and NO responses, despite evidence of macrophage activation and up-regulation of MHC class II molecules. We demonstrate that although minor MyD88-independent responses to live Listeria do occur, these are insufficient for normal host defense. Lastly, we performed experiments in vitro in which macrophages deficient in TLR2 or MyD88 were directly infected with Listeria: Although TLR signaling was required for macrophage NO and cytokine production in response to Listeria, handling and direct killing of Listeria by activated macrophages occurred by TLR2- and MyD88-independent mechanisms.
Collapse
MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens, Differentiation/genetics
- Antigens, Differentiation/physiology
- Bone Marrow Cells/enzymology
- Bone Marrow Cells/immunology
- Bone Marrow Cells/microbiology
- Drosophila Proteins
- Genetic Predisposition to Disease
- Immunity, Innate/genetics
- Inflammation/genetics
- Inflammation/microbiology
- Inflammation/prevention & control
- Interferon-gamma/pharmacology
- Listeria monocytogenes/growth & development
- Listeria monocytogenes/immunology
- Listeriosis/genetics
- Listeriosis/immunology
- Listeriosis/microbiology
- Macrophage Activation/genetics
- Macrophage Activation/immunology
- Macrophages/enzymology
- Macrophages/immunology
- Macrophages/microbiology
- Membrane Glycoproteins/deficiency
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Myeloid Differentiation Factor 88
- Nitric Oxide Synthase/deficiency
- Nitric Oxide Synthase/genetics
- Nitric Oxide Synthase/physiology
- Nitric Oxide Synthase Type II
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Receptors, Immunologic/deficiency
- Receptors, Immunologic/genetics
- Receptors, Immunologic/physiology
- Toll-Like Receptor 2
- Toll-Like Receptors
Collapse
Affiliation(s)
- Brian T Edelson
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | |
Collapse
|
166
|
Martin MU, Wesche H. Summary and comparison of the signaling mechanisms of the Toll/interleukin-1 receptor family. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1592:265-80. [PMID: 12421671 DOI: 10.1016/s0167-4889(02)00320-8] [Citation(s) in RCA: 292] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Toll/interleukin-1 (IL-1) receptor (TIR) family comprises two groups of transmembrane proteins, which share functional and structural properties. The members of the IL-1 receptor (IL-1R) subfamily are characterized by three extracellular immunoglobulin (Ig)-like domains. They form heterodimeric signaling receptor complexes consisting of receptor and accessory proteins. The members of the Toll-like receptor (TLR) subfamily recognize alarm signals that can be derived either from pathogens or the host itself. TLRs possess leucine-rich repeats in their extracellular part. TLRs can form dimeric receptor complexes consisting of two different TLRs or homodimers in the case of TLR4. The TLR4 receptor complex requires supportive molecules for optimal response to its ligand lipopolysaccharide (LPS). A hallmark of the TIR family is the cytoplasmic TIR domain that is indispensable for signal transduction. The TIR domain serves as a scaffold for a series of protein-protein interactions which result in the activation of a unique signaling module consisting of MyD88, interleukin-1 receptor associated kinase (IRAK) family members and Tollip, which is used exclusively by TIR family members. Subsequently, several central signaling pathways are activated in parallel, the activation of NFkappaB being the most prominent event of the inflammatory response. Recent developments indicate that in addition to the common signaling module MyD88/IRAK/Tollip, other molecules can modulate signaling by TLRs, especially of TLR4, resulting in differential biological answers to distinct pathogenic structures. Subtle differences in TLR signaling pathways are now becoming apparent, which reveal how the innate immune system decides at a very early stage the direction in which the adaptive immune response will develop. The creation of pathogen-specific mediator environments by dendritic cells defines whether a cellular or humoral response will be activated in response to the pathogen.
Collapse
MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens, Differentiation/physiology
- Carrier Proteins/physiology
- Drosophila Proteins
- Humans
- Interleukin-1 Receptor-Associated Kinases
- Interleukin-18/chemistry
- Interleukin-18 Receptor alpha Subunit
- Intracellular Signaling Peptides and Proteins
- Membrane Glycoproteins/chemistry
- Membrane Glycoproteins/physiology
- Models, Molecular
- Myeloid Differentiation Factor 88
- Protein Kinases/physiology
- Protein Structure, Tertiary
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/physiology
- Receptors, Immunologic/physiology
- Receptors, Interleukin/chemistry
- Receptors, Interleukin/physiology
- Receptors, Interleukin-1/chemistry
- Receptors, Interleukin-1/physiology
- Receptors, Interleukin-18
- Signal Transduction
- Toll-Like Receptor 4
- Toll-Like Receptors
Collapse
Affiliation(s)
- Michael U Martin
- Institute of Pharmacology OE 5320, Hannover Medical School, Germany.
| | | |
Collapse
|
167
|
Abstract
The family of Toll-like receptors (TLRs) plays a key role in mediating innate immune responses to numerous luminal commensal- and pathogen-derived pattern molecules by the intestinal mucosa. Recent findings have identified several ligands recognized by TLRs as well as the complex downstream signaling effects resulting from activation of these receptors. Understanding is emerging of the importance of TLRs in mucosal host defense-potentially triggering gastrointestinal diseases.
Collapse
Affiliation(s)
- Elke Cario
- Division of Gastroenterology and Hepatology, University of Essen, Essen, Germany.
| |
Collapse
|
168
|
Seki E, Tsutsui H, Tsuji NM, Hayashi N, Adachi K, Nakano H, Futatsugi-Yumikura S, Takeuchi O, Hoshino K, Akira S, Fujimoto J, Nakanishi K. Critical Roles of Myeloid Differentiation Factor 88-Dependent Proinflammatory Cytokine Release in Early Phase Clearance ofListeria monocytogenesin Mice. THE JOURNAL OF IMMUNOLOGY 2002; 169:3863-8. [PMID: 12244183 DOI: 10.4049/jimmunol.169.7.3863] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Listeria monocytogenes (LM), a facultative intracellular Gram-positive bacterium, often causes lethal infection of the host. In this study we investigated the molecular mechanism underlying LM eradication in the early phase of infection. Upon infection with LM, both IL-12 and IL-18 were produced, and then they synergistically induced IFN-gamma production, leading to normal LM clearance in the host. IFN-gamma knockout (KO) mice were highly susceptible to LM infection. IL-12/IL-18 double knockout mice were also highly susceptible. Their susceptibility was less than that of IFN-gamma KO mice, but more than that of single IL-12 or IL-18 KO mice. Mice deficient in myeloid differentiation factor 88 (MyD88), an essential adaptor molecule used by signal transduction pathways of all members of the Toll-like receptor (TLR) family, showed an inability to produce IL-12 and IFN-gamma following LM infection and were most susceptible to LM. Furthermore, MyD88-deficient, but not IFN-gamma-deficient, Kupffer cells could not produce TNF-alpha in response to LM in vitro, indicating the importance of MyD88-dependent TNF-alpha production for host defense. As TLR2 KO, but not TLR4 KO, mice showed partial impairment in their capacity to produce IL-12, IFN-gamma, and TNF-alpha, TLR2 activation partly contributed to the induction of IL-12-mediated IFN-gamma production. These results indicated a critical role for TLRs/MyD88-dependent IL-12/TNF-alpha production and for IL-12- and IL-18-mediated IFN-gamma production in early phase clearance of LM.
Collapse
Affiliation(s)
- Ekihiro Seki
- First Department of Surgery and Department of Immunology and Medical Zoology, Hyogo College of Medicine, Nishinomiya, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
169
|
Konishi H, Tsutsui H, Murakami T, Yumikura-Futatsugi S, Yamanaka KI, Tanaka M, Iwakura Y, Suzuki N, Takeda K, Akira S, Nakanishi K, Mizutani H. IL-18 contributes to the spontaneous development of atopic dermatitis-like inflammatory skin lesion independently of IgE/stat6 under specific pathogen-free conditions. Proc Natl Acad Sci U S A 2002; 99:11340-5. [PMID: 12151598 PMCID: PMC123258 DOI: 10.1073/pnas.152337799] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Atopic dermatitis (AD) is a pruritic inflammatory skin disease. Because IL-18 directly stimulates T cells and mast cells to release AD-associated molecules, Th2 cytokines, and histamine, we investigated the capacity of IL-18 to induce AD-like inflammatory skin disease by analyzing KIL-18Tg and KCASP1Tg, which skin-specifically overexpress IL-18 and caspase-1, respectively. They spontaneously developed relapsing dermatitis with mastocytosis and Th2 cytokine accumulation accompanied by systemic elevation of IgE and histamine. Stat6-deficient KCASP1Tg displayed undetectable levels of IgE but manifested the same degree of cutaneous changes, whereas IL-18-deficient KCASP1Tg evaded the dermatitis, suggesting that IL-18 causes the skin changes in the absence of IgE/stat6. KIL-18Tg and IL-1-deficient KCASP1Tg took longer to display the lesion than KCASP1Tg. Thus, AD-like inflammation is initiated by overrelease of IL-18 and accelerated by IL-1. Our present study might provide insight into understanding the pathogenesis of and establishing therapeutics for chronic inflammatory skin diseases including AD.
Collapse
Affiliation(s)
- Hiroshi Konishi
- Department of Dermatology, Mie University School of Medicine, Tsu 514-8507, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
170
|
Raeburn CD, Dinarello CA, Zimmerman MA, Calkins CM, Pomerantz BJ, McIntyre RC, Harken AH, Meng X. Neutralization of IL-18 attenuates lipopolysaccharide-induced myocardial dysfunction. Am J Physiol Heart Circ Physiol 2002; 283:H650-7. [PMID: 12124212 DOI: 10.1152/ajpheart.00043.2002] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) have been implicated in cardiac dysfunction during endotoxemia. Because IL-18 is a proinflammatory cytokine known to mediate the production of TNF-alpha and IL-1beta and to induce the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), we hypothesized that neutralization of IL-18 would attenuate lipopolysaccharide (LPS)-induced cardiac dysfunction. Mice (C57BL/6) were injected with LPS (0.5 mg/kg ip) or vehicle (normal saline), and left ventricular developed pressure (LVDP) was determined by the Langendorff technique. LVDP was depressed by 38% at 6 h after LPS. LPS-induced myocardial dysfunction was associated with increased myocardial levels of TNF-alpha and IL-1beta as well as increased expression of ICAM-1/VCAM-1. Pretreatment with neutralizing anti-mouse IL-18 antibody attenuated LPS-induced myocardial dysfunction (by 92%) and was associated with reduced myocardial IL-1beta production (65% reduction) and ICAM-1/VCAM-1 expression (50% and 35% reduction, respectively). However, myocardial TNF-alpha levels were not influenced by neutralization of IL-18. In conclusion, neutralization of IL-18 protects against LPS-induced myocardial dysfunction. IL-18 may mediate endotoxemic myocardial dysfunction through induction of and/or synergy with IL-1beta, ICAM-1, and VCAM-1.
Collapse
Affiliation(s)
- Christopher D Raeburn
- Department of Surgery, University of Colorado Health Sciences Center, 4200 E. Ninth Avenue, Box C-320, Denver, CO 80262, USA.
| | | | | | | | | | | | | | | |
Collapse
|
171
|
Ahmed ST, Mayer A, Ji J, Ivashkiv LB. Inhibition of IL‐6 signaling by a p38‐dependent pathway occurs in the absence of new protein synthesis. J Leukoc Biol 2002. [DOI: 10.1189/jlb.72.1.154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Simi T. Ahmed
- Graduate Program in Immunology, Weill Graduate School of Medical Sciences of Cornell University, and New York, New York
| | - Alexander Mayer
- Department of Medicine, Hospital for Special Surgery, Weill Medical College of Cornell University, New York, New York
| | - Jong‐Dae Ji
- Department of Medicine, Hospital for Special Surgery, Weill Medical College of Cornell University, New York, New York
| | - Lionel B. Ivashkiv
- Graduate Program in Immunology, Weill Graduate School of Medical Sciences of Cornell University, and New York, New York
- Department of Medicine, Hospital for Special Surgery, Weill Medical College of Cornell University, New York, New York
| |
Collapse
|
172
|
Scanga CA, Aliberti J, Jankovic D, Tilloy F, Bennouna S, Denkers EY, Medzhitov R, Sher A. Cutting edge: MyD88 is required for resistance to Toxoplasma gondii infection and regulates parasite-induced IL-12 production by dendritic cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:5997-6001. [PMID: 12055206 DOI: 10.4049/jimmunol.168.12.5997] [Citation(s) in RCA: 355] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Host resistance to the intracellular protozoan Toxoplasma gondii is highly dependent on early IL-12 production by APC. We demonstrate here that both host resistance and T. gondii-induced IL-12 production are dramatically reduced in mice lacking the adaptor molecule MyD88, an important signaling element used by Toll-like receptor (TLR) family members. Infection of MyD88-deficient mice with T. gondii resulted in uncontrolled parasite replication and greatly reduced plasma IL-12 levels. Defective IL-12 responses to T. gondii Ags (soluble tachyzoite Ag (STAg)) were observed in MyD88(-/-) peritoneal macrophages, neutrophils, and splenic dendritic cells (DC). In contrast, DC from TLR2- or TLR4-deficient animals developed normal IL-12 responses to STAg. In vivo treatment with pertussis toxin abolished the residual IL-12 response displayed by STAg-stimulated DC from MyD88(-/-) mice. Taken together, these data suggest that the induction of IL-12 by T. gondii depends on a unique mechanism involving both MyD88 and G protein-coupled signaling pathways.
Collapse
MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens, Differentiation/genetics
- Antigens, Differentiation/physiology
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Dendritic Cells/parasitology
- Drosophila Proteins
- Female
- Immunity, Innate/genetics
- Interferon-gamma/biosynthesis
- Interferon-gamma/deficiency
- Interleukin-12/biosynthesis
- Interleukin-12/deficiency
- Macrophages, Peritoneal/immunology
- Macrophages, Peritoneal/metabolism
- Macrophages, Peritoneal/parasitology
- Male
- Membrane Glycoproteins/deficiency
- Membrane Glycoproteins/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Myeloid Differentiation Factor 88
- Neutrophils/immunology
- Neutrophils/metabolism
- Neutrophils/parasitology
- Receptors, CCR5/physiology
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/physiology
- Receptors, Immunologic/deficiency
- Receptors, Immunologic/genetics
- Receptors, Immunologic/physiology
- Signal Transduction/immunology
- Toll-Like Receptor 2
- Toll-Like Receptor 4
- Toll-Like Receptors
- Toxoplasma/immunology
- Toxoplasmosis, Animal/genetics
- Toxoplasmosis, Animal/immunology
- Toxoplasmosis, Animal/mortality
- Toxoplasmosis, Animal/parasitology
Collapse
Affiliation(s)
- Charles A Scanga
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | | | | | | | | | | | | | | |
Collapse
|
173
|
Nomura T, Kawamura I, Tsuchiya K, Kohda C, Baba H, Ito Y, Kimoto T, Watanabe I, Mitsuyama M. Essential role of interleukin-12 (IL-12) and IL-18 for gamma interferon production induced by listeriolysin O in mouse spleen cells. Infect Immun 2002; 70:1049-55. [PMID: 11854182 PMCID: PMC127750 DOI: 10.1128/iai.70.3.1049-1055.2002] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanism of gamma interferon (IFN-gamma) production induced by listeriolysin O (LLO), a cytolytic virulence factor of Listeria monocytogenes, was analyzed with special reference to the involvement of macrophage-derived cytokines in spleen cells of mice. LLO purified from the culture supernatant of L. monocytogenes was capable of inducing a high level of IFN-gamma when its cytolytic activity was blocked by cholesterol treatment. The IFN-gamma-inducing ability of LLO was not dependent on possibly contaminating lipopolysaccharide. Depletion of CD11b(+) cells resulted in a profound decrease in IFN-gamma production in response to LLO stimulation. Negative selection also suggested the contribution of DX5(+) cells in IFN-gamma production. Reverse transcription-PCR revealed that expression of interleukin-12 (IL-12) p35 and p40 was induced by LLO but that the IL-18 mRNA level in the CD11b(+) fraction of spleen cells was unchanged. There was no change in the expression of the IFN-gamma-inducing cytokine genes in the CD11b(-) fraction. Neutralization of IL-12 and IL-18 in culture abolished the IFN-gamma production almost completely. Spleen cells from IL-12- or IL-18-deficient mice never produced IFN-gamma after stimulation with LLO. These results clearly indicated that LLO, a well-known virulence factor of L. monocytogenes, is capable of inducing IFN-gamma from NK cells through induction of IL-12 and IL-18 from macrophages. LLO appeared to play essential roles, not only as a bacterial virulence factor but also as a bacterial modulin in the immune response of the host.
Collapse
Affiliation(s)
- Takamasa Nomura
- Department of Microbiology, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8501, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
174
|
Abstract
The ability of a host to sense invasion by pathogenic organisms and to respond appropriately to control infection is paramount to survival. In the case of sepsis and septic shock, however, an exaggerated systemic response may, in fact, contribute to the morbidity and mortality associated with overwhelming infections. The innate immune system has evolved as the first line of defense against invading microorganisms. The Toll-like receptors (TLRs) are a part of this innate immune defense, recognizing conserved patterns on microorganisms. These TLRs and their signaling pathways are represented in such diverse creatures as mammals, fruit flies, and plants. Ten members of the TLR family have been identified in humans, and several of them appear to recognize specific microbial products, including lipopolysaccharide, bacterial lipoproteins, peptidoglycan, and bacterial DNA. Signals initiated by the interaction of TLRs with specific microbial patterns direct the subsequent inflammatory response. Thus, TLR signaling represents a key component of the innate immune response to microbial infection.
Collapse
|
175
|
Abstract
The mammalian Toll-like receptors (TLRs) are expressed on macrophages and dendritic cells, which are primarily involved in innate immunity. At present, ligands for several of the TLRs, such as TLR2, TLR3, TLR4, TLR5, TLR6, and TLR9, have been identified. Most of these ligands are derived from pathogens, but not found in the host, suggesting that the TLRs are critical to sensing invading microorganisms. Pathogen recognition by TLRs provokes rapid activation of innate immunity by inducing production of proinflammatory cytokines and upregulation of costimulatory molecules. Activated innate immunity subsequently leads to effective adaptive immunity. In this regard, the TLRs are considered to be adjuvant receptors. Distinct TLRs can exert distinct, but overlapping sets of biological effects. Accumulating evidence indicates that this can be attributed to both the common and unique aspects of the signaling mechanisms that mediate TLR family responses. For example, TLR2 and TLR9 require MyD88 as an essential signal transducer, whereas TLR4 can induce costimulatory molecule upregulation in a MyD88-independent manner. Understanding the TLR system should offer invaluable opportunity for manipulating host immune responses.
Collapse
Affiliation(s)
- Tsuneyasu Kaisho
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | | |
Collapse
|
176
|
Adachi K, Tsutsui H, Kashiwamura S, Seki E, Nakano H, Takeuchi O, Takeda K, Okumura K, Van Kaer L, Okamura H, Akira S, Nakanishi K. Plasmodium berghei infection in mice induces liver injury by an IL-12- and toll-like receptor/myeloid differentiation factor 88-dependent mechanism. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:5928-34. [PMID: 11698470 DOI: 10.4049/jimmunol.167.10.5928] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Malaria, caused by infection with Plasmodium spp., is a life cycle-specific disease that includes liver injury at the erythrocyte stage of the parasite. In this study, we have investigated the mechanisms underlying Plasmodium berghei-induced liver injury, which is characterized by the presence of apoptotic and necrotic hepatocytes and dense infiltration of lymphocytes. Although both IL-12 and IL-18 serum levels were elevated after infection, IL-12-deficient, but not IL-18-deficient, mice were resistant to liver injury induced by P. berghei. Neither elevation of serum IL-12 levels nor liver injury was observed in mice deficient in myeloid differentiation factor 88 (MyD88), an adaptor molecule shared by Toll-like receptors (TLRs). These results demonstrated a requirement of the TLR-MyD88 pathway for induction of IL-12 production during P. berghei infection. Hepatic lymphocytes from P. berghei-infected wild-type mice lysed hepatocytes from both uninfected and infected mice. The hepatocytotoxic action of these cells was blocked by a perforin inhibitor but not by a neutralizing anti-Fas ligand Ab and was up-regulated by IL-12. Surprisingly, these cells killed hepatocytes in an MHC-unrestricted manner. However, CD1d-deficient mice that lack CD1d-restricted NK T cells, were susceptible to liver injury induced by P. berghei. Collectively, our results indicate that the liver injury induced by P. berghei infection of mice induces activation of the TLR-MyD88 signaling pathway which results in IL-12 production and activation of the perforin-dependent cytotoxic activities of MHC-unrestricted hepatic lymphocytes.
Collapse
MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens, CD1/analysis
- Antigens, CD1d
- Antigens, Differentiation/genetics
- Antigens, Differentiation/physiology
- Cytotoxicity Tests, Immunologic
- Drosophila Proteins
- Fas Ligand Protein
- Female
- Hepatitis, Animal/etiology
- Hepatitis, Animal/parasitology
- Hepatitis, Animal/pathology
- Interleukin-12/genetics
- Interleukin-12/physiology
- Interleukin-18/genetics
- Interleukin-18/physiology
- Killer Cells, Natural/immunology
- Liver/pathology
- Malaria/etiology
- Malaria/pathology
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/physiology
- Mice
- Mice, Knockout
- Myeloid Differentiation Factor 88
- Perforin
- Plasmodium berghei
- Pore Forming Cytotoxic Proteins
- Receptors, Cell Surface/physiology
- Receptors, Immunologic
- T-Lymphocyte Subsets/immunology
- Toll-Like Receptors
- fas Receptor/physiology
Collapse
Affiliation(s)
- K Adachi
- Department of Immunology and Medical Zoology, Institute for Advanced Medical Science, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
177
|
Abstract
Toll-like receptors have a crucial role in the detection of microbial infection in mammals and insects. In mammals, these receptors have evolved to recognize conserved products unique to microbial metabolism. This specificity allows the Toll proteins to detect the presence of infection and to induce activation of inflammatory and antimicrobial innate immune responses. Recognition of microbial products by Toll-like receptors expressed on dendritic cells triggers functional maturation of dendritic cells and leads to initiation of antigen-specific adaptive immune responses.
Collapse
Affiliation(s)
- R Medzhitov
- Section of Immunobiology, Yale University School Medicine, and Howard Hughes Medical Institute, New Haven, Connecticut 06520, USA.
| |
Collapse
|
178
|
Abstract
Although interleukin-18 is structurally homologous to IL-1 and its receptor belongs to the IL-1R/Toll-like receptor (TLR) superfamily, its function is quite different from that of IL-1. IL-18 is produced not only by types of immune cells but also by non-immune cells. In collaboration with IL-12, IL-18 stimulates Th1-mediated immune responses, which play a critical role in the host defense against infection with intracellular microbes through the induction of IFN-gamma. However, the overproduction of IL-12 and IL-18 induces severe inflammatory disorders, suggesting that IL-18 is a potent proinflammatory cytokine that has pathophysiological roles in several inflammatory conditions. IL-18 mRNA is expressed in a wide range of cells including Kupffer cells, macrophages, T cells, B cells, dendritic cells, osteoblasts, keratinocytes, astrocytes, and microglia. Thus, the pathophysiological role of IL-18 has been extensively tested in the organs that contain these cells. Somewhat surprisingly, IL-18 alone can stimulate Th2 cytokine production as well as allergic inflammation. Therefore, the functions of IL-18 in vivo are very heterogeneous and complicated. In principle, IL-18 enhances the IL-12-driven Th1 immune responses, but it can also stimulate Th2 immune responses in the absence of IL-12.
Collapse
Affiliation(s)
- K Nakanishi
- Department of Immunology and Medical Zoology, Institute for Advanced Medical Sciences, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan.
| | | | | | | |
Collapse
|
179
|
Akira S, Takeda K, Kaisho T. Toll-like receptors: critical proteins linking innate and acquired immunity. Nat Immunol 2001; 2:675-80. [PMID: 11477402 DOI: 10.1038/90609] [Citation(s) in RCA: 3403] [Impact Index Per Article: 148.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recognition of pathogens is mediated by a set of germline-encoded receptors that are referred to as pattern-recognition receptors (PRRs). These receptors recognize conserved molecular patterns (pathogen-associated molecular patterns), which are shared by large groups of microorganisms. Toll-like receptors (TLRs) function as the PRRs in mammals and play an essential role in the recognition of microbial components. The TLRs may also recognize endogenous ligands induced during the inflammatory response. Similar cytoplasmic domains allow TLRs to use the same signaling molecules used by the interleukin 1 receptors (IL-1Rs): these include MyD88, IL-1R--associated protein kinase and tumor necrosis factor receptor--activated factor 6. However, evidence is accumulating that the signaling pathways associated with each TLR are not identical and may, therefore, result in different biological responses.
Collapse
Affiliation(s)
- S Akira
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.
| | | | | |
Collapse
|
180
|
Itoi H, Fujimori Y, Tsutsui H, Matsui K, Futatsugi S, Okamura H, Hara H, Hada T, Kakishita E, Nakanishi K. Fas ligand-induced caspase-1-dependent accumulation of interleukin-18 in mice with acute graft-versus-host disease. Blood 2001; 98:235-7. [PMID: 11418486 DOI: 10.1182/blood.v98.1.235] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acute graft-versus-host disease (aGVHD), the fatal side effects of bone marrow transplantation, was shown to be accompanied by elevation of serum levels of interleukin 18 (IL-18). In this study, the mechanism underlying the accumulation of IL-18 in aGVHD in mice was investigated. Lethally irradiated recipients having transplantation with H-2 disparate donor splenocytes demonstrated aGVHD and contained markedly elevated serum levels of IL-18. In contrast, recipients having transplantation with gld/gld spleen cells, which lack functional Fas ligand (FasL), contained only normal ranges of IL-18, indicating FasL-mediated IL-18 release in aGVHD. The wild-type hosts engrafted with caspase-1-deficient cells revealed marked increases of IL-18 similar to those engrafted with wild-type cells, whereas caspase-1-deficient recipients engrafted with wild-type cells showed only a slight elevation of serum IL-18, indicating that IL-18 elevation is derived from host cells in a caspase-1-dependent manner. These results suggest FasL-mediated caspase-1-dependent IL-18 secretion in aGVHD in mice.
Collapse
Affiliation(s)
- H Itoi
- Second Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|