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Wang ZY, Gao ST, Gou XJ, Qiu FR, Feng Q. IL-1 receptor-associated kinase family proteins: An overview of their role in liver disease. Eur J Pharmacol 2024; 978:176773. [PMID: 38936453 DOI: 10.1016/j.ejphar.2024.176773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 06/16/2024] [Accepted: 06/23/2024] [Indexed: 06/29/2024]
Abstract
The interleukin-1 receptor-associated kinase (IRAK) family is a group of serine-threonine kinases that regulates various cellular processes via toll-like receptor (TLR)/interleukin-1 receptor (IL1R)-mediated signaling. The IRAK family comprises four members, including IRAK1, IRAK2, IRAK3, and IRAK4, which play an important role in the expression of various inflammatory genes, thereby contributing to the inflammatory response. IRAKs are key proteins in chronic and acute liver diseases, and recent evidence has implicated IRAK family proteins (IRAK1, IRAK3, and IRAK4) in the progression of liver-related disorders, including alcoholic liver disease, non-alcoholic steatohepatitis, hepatitis virus infection, acute liver failure, liver ischemia-reperfusion injury, and hepatocellular carcinoma. In this article, we provide a comprehensive review of the role of IRAK family proteins and their associated inflammatory signaling pathways in the pathogenesis of liver diseases. The purpose of this study is to explore whether IRAK family proteins can serve as the main target for the treatment of liver related diseases.
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Affiliation(s)
- Zhuo-Yuan Wang
- Institute of Liver Diseases, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Si-Ting Gao
- Institute of Liver Diseases, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Xiao-Jun Gou
- Central Laboratory, Baoshan District Hospital of Integrated Traditional Chinese and Western Medicine of Shanghai, Shanghai University of Traditional Chinese Medicine, Shanghai, 201999, China
| | - Fu-Rong Qiu
- Laboratory of Clinical Pharmacokinetics, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
| | - Qin Feng
- Institute of Liver Diseases, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China; Central Laboratory, ShuGuang Hospital Affiliated to Shanghai University of Chinese Traditional Medicine, Shanghai, 201203, China; Key Laboratory of Liver and Kidney Diseases, Shanghai University of Traditional Chinese Medicine, Ministry of Education, Shanghai, 201203, China.
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2
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Saleki K, Alijanizadeh P, Javanmehr N, Rezaei N. The role of Toll-like receptors in neuropsychiatric disorders: Immunopathology, treatment, and management. Med Res Rev 2024; 44:1267-1325. [PMID: 38226452 DOI: 10.1002/med.22012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 10/20/2023] [Accepted: 12/20/2023] [Indexed: 01/17/2024]
Abstract
Neuropsychiatric disorders denote a broad range of illnesses involving neurology and psychiatry. These disorders include depressive disorders, anxiety, schizophrenia, bipolar disorder, attention deficit hyperactivity disorder, autism spectrum disorders, headaches, and epilepsy. In addition to their main neuropathology that lies in the central nervous system (CNS), lately, studies have highlighted the role of immunity and neuroinflammation in neuropsychiatric disorders. Toll-like receptors (TLRs) are innate receptors that act as a bridge between the innate and adaptive immune systems via adaptor proteins (e.g., MYD88) and downstream elements; TLRs are classified into 13 families that are involved in normal function and illnesses of the CNS. TLRs expression affects the course of neuropsychiatric disorders, and is influenced during their pharmacotherapy; For example, the expression of multiple TLRs is normalized during the major depressive disorder pharmacotherapy. Here, the role of TLRs in neuroimmunology, treatment, and management of neuropsychiatric disorders is discussed. We recommend longitudinal studies to comparatively assess the cell-type-specific expression of TLRs during treatment, illness progression, and remission. Also, further research should explore molecular insights into TLRs regulation and related pathways.
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Affiliation(s)
- Kiarash Saleki
- Student Research Committee, Babol University of Medical Sciences, Babol, Iran
- USERN Office, Babol University of Medical Sciences, Babol, Iran
- Department of e-Learning, Virtual School of Medical Education and Management, Shahid Beheshti University of Medical Sciences (SBMU), Tehran, Iran
| | - Parsa Alijanizadeh
- Student Research Committee, Babol University of Medical Sciences, Babol, Iran
- USERN Office, Babol University of Medical Sciences, Babol, Iran
| | - Nima Javanmehr
- Student Research Committee, Babol University of Medical Sciences, Babol, Iran
- USERN Office, Babol University of Medical Sciences, Babol, Iran
| | - Nima Rezaei
- Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Tehran, Iran
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3
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Boraschi D. What Is IL-1 for? The Functions of Interleukin-1 Across Evolution. Front Immunol 2022; 13:872155. [PMID: 35464444 PMCID: PMC9020223 DOI: 10.3389/fimmu.2022.872155] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/11/2022] [Indexed: 11/13/2022] Open
Abstract
Interleukin-1 is a cytokine with potent inflammatory and immune-amplifying effects, mainly produced by macrophages during defensive reactions. In mammals, IL-1 is a superfamily of eleven structurally similar proteins, all involved in inflammation or its control, which mainly act through binding to specific receptors on the plasma membrane of target cells. IL-1 receptors are also a family of ten structurally similar transmembrane proteins that assemble in heterocomplexes. In addition to their innate immune/inflammatory effects, the physiological role of IL-1 family cytokines seems to be linked to the development of adaptive immunity in vertebrates. We will discuss why IL-1 developed in vertebrates and what is its physiological role, as a basis for understanding when and how it can be involved in the initiation and establishment of pathologies.
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Affiliation(s)
- Diana Boraschi
- Shenzhen Institute of Advanced Technology (SIAT), Chinese Academy of Science (CAS), Shenzhen, China.,Institute of Biochemistry and Cell Biology (IBBC), National Research Council (CNR), Napoli, Italy.,Stazione Zoologica Anton Dohrn, Napoli, Italy
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Griffiths JS, Camilli G, Kotowicz NK, Ho J, Richardson JP, Naglik JR. Role for IL-1 Family Cytokines in Fungal Infections. Front Microbiol 2021; 12:633047. [PMID: 33643264 PMCID: PMC7902786 DOI: 10.3389/fmicb.2021.633047] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/15/2021] [Indexed: 12/15/2022] Open
Abstract
Fungal pathogens kill approximately 1.5 million individuals per year and represent a severe disease burden worldwide. It is estimated over 150 million people have serious fungal disease such as recurrent mucosal infections or life-threatening systemic infections. Disease can ensue from commensal fungi or new infection and involves different fungal morphologies and the expression of virulence factors. Therefore, anti-fungal immunity is complex and requires coordination between multiple facets of the immune system. IL-1 family cytokines are associated with acute and chronic inflammation and are essential for the innate response to infection. Recent research indicates IL-1 cytokines play a key role mediating immunity against different fungal infections. During mucosal disease, IL-1R and IL-36R are required for neutrophil recruitment and protective Th17 responses, but function through different mechanisms. During systemic disease, IL-18 drives protective Th1 responses, while IL-33 promotes Th2 and suppresses Th1 immunity. The IL-1 family represents an attractive anti-fungal immunotherapy target. There is a need for novel anti-fungal therapeutics, as current therapies are ineffective, toxic and encounter resistance, and no anti-fungal vaccine exists. Furthering our understanding of the IL-1 family cytokines and their complex role during fungal infection may aid the development of novel therapies. As such, this review will discuss the role for IL-1 family cytokines in fungal infections.
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Affiliation(s)
- James S Griffiths
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London, United Kingdom
| | - Giorgio Camilli
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London, United Kingdom
| | - Natalia K Kotowicz
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London, United Kingdom
| | - Jemima Ho
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London, United Kingdom
| | - Jonathan P Richardson
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London, United Kingdom
| | - Julian R Naglik
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London, United Kingdom
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5
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The IL-1 family of cytokines and receptors in rheumatic diseases. Nat Rev Rheumatol 2019; 15:612-632. [DOI: 10.1038/s41584-019-0277-8] [Citation(s) in RCA: 168] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2019] [Indexed: 02/07/2023]
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6
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Li Z, Liu XM, Li AY, Du XX, Wang XB, Liu JX, Wang ZG, Zhang QQ, Yu HY. Teleost Type 2 Interleukin-1 Receptor (IL-1R2) from the Spotted Halibut (Verasper variegatus): 3D Structure and a Role in Immune Response. Mol Biol 2019. [DOI: 10.1134/s0026893319020109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
The extracellular forms of the IL-1 cytokines are active through binding to specific receptors on the surface of target cells. IL-1 ligands bind to the extracellular portion of their ligand-binding receptor chain. For signaling to take place, a non-binding accessory chain is recruited into a heterotrimeric complex. The intracellular approximation of the Toll-IL-1-receptor (TIR) domains of the 2 receptor chains is the event that initiates signaling. The family of IL-1 receptors (IL-1R) includes 10 structurally related members, and the distantly related soluble protein IL-18BP that acts as inhibitor of the cytokine IL-18. Over the years the receptors of the IL-1 family have been known with many different names, with significant confusion. Thus, we will use here a recently proposed unifying nomenclature. The family includes several ligand-binding chains (IL-1R1, IL-1R2, IL-1R4, IL-1R5, and IL-1R6), 2 types of accessory chains (IL-1R3, IL-1R7), molecules that act as inhibitors of signaling (IL-1R2, IL-1R8, IL-18BP), and 2 orphan receptors (IL-1R9, IL-1R10). In this review, we will examine how the receptors of the IL-1 family regulate the inflammatory and anti-inflammatory functions of the IL-1 cytokines and are, more at large, involved in modulating defensive and pathological innate immunity and inflammation. Regulation of the IL-1/IL-1R system in the brain will be also described, as an example of the peculiarities of organ-specific modulation of inflammation.
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Affiliation(s)
- Diana Boraschi
- Institute of Protein Biochemistry, National Research Council, Naples, Italy
| | - Paola Italiani
- Institute of Protein Biochemistry, National Research Council, Naples, Italy
| | - Sabrina Weil
- Immunology FB08, Justus-Liebig-Universitat Giessen, Giessen, Germany
| | - Michael U Martin
- Immunology FB08, Justus-Liebig-Universitat Giessen, Giessen, Germany
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Abstract
The interleukin-1 (IL-1) family of cytokines and receptors is unique in immunology because the IL-1 family and Toll-like receptor (TLR) families share similar functions. More than any other cytokine family, the IL-1 family is primarily associated with innate immunity. More than 95% of living organisms use innate immune mechanisms for survival whereas less than 5% depend on T- and B-cell functions. Innate immunity is manifested by inflammation, which can function as a mechanism of host defense but when uncontrolled is detrimental to survival. Each member of the IL-1 receptor and TLR family contains the cytoplasmic Toll-IL-1-Receptor (TIR) domain. The 50 amino acid TIR domains are highly homologous with the Toll protein in Drosophila. The TIR domain is nearly the same and present in each TLR and each IL-1 receptor family. Whereas IL-1 family cytokine members trigger innate inflammation via IL-1 family of receptors, TLRs trigger inflammation via bacteria, microbial products, viruses, nucleic acids, and damage-associated molecular patterns (DAMPs). In fact, IL-1 family member IL-1a and IL-33 also function as DAMPs. Although the inflammatory properties of the IL-1 family dominate in innate immunity, IL-1 family member can play a role in acquired immunity. This overview is a condensed update of the IL-1 family of cytokines and receptors.
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Affiliation(s)
- Charles A. Dinarello
- Department of Medicine, University of Colorado Denver, Aurora, CO, USA
- Department of Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
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9
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Bergman P, Seyedoleslami Esfahani S, Engström Y. Drosophila as a Model for Human Diseases—Focus on Innate Immunity in Barrier Epithelia. Curr Top Dev Biol 2017; 121:29-81. [DOI: 10.1016/bs.ctdb.2016.07.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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10
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Toll-like receptors and chronic inflammation in rheumatic diseases: new developments. Nat Rev Rheumatol 2016; 12:344-57. [PMID: 27170508 DOI: 10.1038/nrrheum.2016.61] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In the past few years, new developments have been reported on the role of Toll-like receptors (TLRs) in chronic inflammation in rheumatic diseases. The inhibitory function of TLR10 has been demonstrated. Receptors that enhance the function of TLRs, and several TLR inhibitors, have been identified. In addition, the role of the microbiome and TLRs in the onset of rheumatic diseases has been reported. We review novel insights on the role of TLRs in several inflammatory joint diseases, including rheumatoid arthritis, systemic lupus erythematosus, gout and Lyme arthritis, with a focus on the signalling mechanisms mediated by the Toll-IL-1 receptor (TIR) domain, the exogenous and endogenous ligands of TLRs, and the current and future therapeutic strategies to target TLR signalling in rheumatic diseases.
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Abstract
For many years innate immunity was regarded as a relatively nonspecific set of mechanisms serving as a first line of defence to contain infections while the more refined adaptive immune response was developing. The discovery of pattern recognition receptors (PRRs) revolutionised the prevailing view of innate immunity, revealing its intimate connection with adaptive immunity and generation of effector and memory T- and B-cell responses. Among the PRRs, families of Toll-like receptors (TLRs), C-type lectin receptors (CLR), retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs) and nucleotide-binding domain, leucine-rich repeat-containing protein receptors (NLRs), along with a number of cytosolic DNA sensors and the family of absent in melanoma (AIM)-like receptors (ALRs), have been characterised. NLR sensors have been a particular focus of attention, and some NLRs have emerged as key orchestrators of the inflammatory response through the formation of large multiprotein complexes termed inflammasomes. However, several other functions not related to inflammasomes have also been described for NLRs. This chapter introduces the different families of PRRs, their signalling pathways, cross-regulation and their roles in immunosurveillance. The structure and function of NLRs is also discussed with particular focus on the non-inflammasome NLRs.
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Radons J, Falk W, Dove S. Identification of critical regions within the TIR domain of IL-1 receptor type I. Int J Biochem Cell Biol 2015; 68:15-20. [PMID: 26279140 DOI: 10.1016/j.biocel.2015.08.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 08/05/2015] [Accepted: 08/11/2015] [Indexed: 10/23/2022]
Abstract
Interleukin-1 receptor type I (IL-1RI) belongs to a superfamily of proteins characterized by an intracellular Toll/IL-1 receptor (TIR) domain. This domain harbors three conserved regions called boxes 1-3 that play crucial roles in mediating IL-1 responses. Boxes 1 and 2 are considered to be involved in binding of adapter molecules. Amino acids possibly crucial for IL-1RI signaling were predicted via homology models of the IL-1RI TIR domain based on the crystal structure of IL-1RAPL. The role of ten of these residues was investigated by site-directed mutagenesis and a functional luciferase assay reflecting NF-κB activity in transiently transfected Jurkat cells. In particular, the mutants E437K/D438K, E472A/E473A and S465A/S470A/S471A/E472A/E473A showed decreased and the mutant E437A/D438A increased IL-1 responsiveness compared to the mouse IL-1RI wild type. In conclusion, the αC' helix (Q469-E473 in mouse IL-1RI) is probably involved in heterotypic interactions of IL-1RI with IL-1RAcP or MyD88.
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Affiliation(s)
- Jürgen Radons
- Department of Internal Medicine I, University Clinic Regensburg, D-93042 Regensburg, Germany.
| | - Werner Falk
- Department of Internal Medicine I, University Clinic Regensburg, D-93042 Regensburg, Germany
| | - Stefan Dove
- Institute of Pharmacy, University of Regensburg, D-93040 Regensburg, Germany
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13
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Dinarello CA. The history of fever, leukocytic pyrogen and interleukin-1. Temperature (Austin) 2015; 2:8-16. [PMID: 27226996 PMCID: PMC4843879 DOI: 10.1080/23328940.2015.1017086] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 02/05/2015] [Indexed: 02/07/2023] Open
Abstract
There has been great progress in the 30 y since the reporting in 1984 of the cDNA for interleukin1 (IL1) β in the human and IL1α in the mouse. However, the history of IL1 begins in the early 1940s with investigations into the nature of an endogenous fever-producing protein released rabbit peritoneal neutrophils. Most researchers in immunology today are unaware that the field of cytokines, particularly the field of inflammatory cytokines. Toll-like receptors and innate immunity traces back to studies on fever. Researchers in infectious diseases wanted to know about an endogenous protein that caused fever, independent of infection. The endogenous fever-producing protein was called by various names: granulocyte, endogenous or leukocytic pyrogen. It is a fascinating and sometimes controversial story for biology and medicine and for the treatment of inflammatory diseases. Few imagined that this fever-producing protein would play such a major role in nearly every cell and in most diseases. This paper reviews the true background and milestones of interleukin1 from the purification of leukocytic pyrogen to the first cDNA of IL1β and the validation of cytokine biology from ill-defined factors to its present day importance.
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Affiliation(s)
- Charles A Dinarello
- Department of Medicine; Division of Infectious Diseases; University of Colorado Denver; Aurora, CO USA; Department of Internal Medicine; Radboud University Medical Center; Nijmegen, The Netherlands
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Carlsen TG, Kjærsgaard P, Jørgensen TL, Foldbjerg R, Nielsen ML, Poulsen TBG, Zabieglo K, Christiansen G, Birkelund S. Interleukin-1α activation and localization in lipopolysaccharide-stimulated human monocytes and macrophages. J Immunol Methods 2015; 422:59-71. [PMID: 25870118 DOI: 10.1016/j.jim.2015.03.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 03/31/2015] [Accepted: 03/31/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Interleukin-1α (IL-1α) is a proinflammatory cytokine belonging to the IL-1 family. It is synthesized as a 33kDa precursor peptide that is cleaved by a calpain-like protease to a 16 kDa propiece and a 17 kDa mature IL-1α peptide. In contrast to its close relative, IL-1β, the role of IL-1α in inflammation is only partly understood. RESULTS Human monocyte derived macrophages, stimulated with lipopolysaccharide (LPS) were analysed for production and localization of IL-1α by use of a monoclonal antibody (MAb) generated against recombinant precursor IL-1α. We found that the MAb detected IL-1α within the nuclei of the cells 2h (hours) after LPS stimulation and production continued for up to 20 h. At no time could we demonstrate cleavage of the IL-1α precursor. The MAb was conjugated to fluorescein isothiocyanate (FITC) for use in flow cytometry. Based on the flow cytometric analysis CD68 positive cells were positive for IL-1α in agreement with CD68 being a marker for monocytes. CONCLUSIONS Here, we demonstrate, for the first time, a method to visualize and measure the production of IL-1α in both human monocytes and macrophages.
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Affiliation(s)
- Thomas Gelsing Carlsen
- Department of Health Science and Technology, Fredrik Bajers Vej 3b, 9220 Aalborg Ø, Denmark.
| | - Pernille Kjærsgaard
- Department of Health Science and Technology, Fredrik Bajers Vej 3b, 9220 Aalborg Ø, Denmark.
| | - Trine Lykke Jørgensen
- Department of Health Science and Technology, Fredrik Bajers Vej 3b, 9220 Aalborg Ø, Denmark.
| | - Rasmus Foldbjerg
- Department of Health Science and Technology, Fredrik Bajers Vej 3b, 9220 Aalborg Ø, Denmark.
| | - Mads Lausen Nielsen
- Department of Health Science and Technology, Fredrik Bajers Vej 3b, 9220 Aalborg Ø, Denmark.
| | | | | | | | - Svend Birkelund
- Department of Health Science and Technology, Fredrik Bajers Vej 3b, 9220 Aalborg Ø, Denmark; Loke Diagnostics, Sindalsvej 17, 8240 Risskov, Denmark.
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Narayanan KB, Park HH. Toll/interleukin-1 receptor (TIR) domain-mediated cellular signaling pathways. Apoptosis 2015; 20:196-209. [DOI: 10.1007/s10495-014-1073-1] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Krumm B, Xiang Y, Deng J. Structural biology of the IL-1 superfamily: key cytokines in the regulation of immune and inflammatory responses. Protein Sci 2014; 23:526-38. [PMID: 24677376 DOI: 10.1002/pro.2441] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/07/2014] [Accepted: 02/10/2014] [Indexed: 12/15/2022]
Abstract
Interleukin-1 superfamily of cytokines (IL-1, IL-18, IL-33) play key roles in inflammation and regulating immunity. The mechanisms of agonism and antagonism in the IL-1 superfamily have been pursued by structural biologists for nearly 20 years. New insights into these mechanisms were recently provided by the crystal structures of the ternary complexes of IL-1β and its receptors. We will review here the structural biology related to receptor recognition by IL-1 superfamily cytokines and the regulation of its cytokine activities by antagonists.
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Affiliation(s)
- Brian Krumm
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
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18
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Abstract
Although IL-1β is the master inflammatory cytokine in the IL-1 family, after more than ten years of continuous breeding, mice deficient in IL-1β exhibit no spontaneous disease. Therefore, one concludes that IL-1β is not needed for homeostasis. However, IL-1β-deficient mice are protected against local and systemic inflammation due to live infections, autoimmune processes, tumor metastasis and even chemical carcinogenesis. Based on a large number of preclinical studies, blocking IL-1β activity in humans with a broad spectrum of inflammatory conditions has reduced disease severity and for many, has lifted the burden of disease. Rare and common diseases are controlled by blocking IL-1β. Immunologically, IL-1β is a natural adjuvant for responses to antigen. Alone, IL-1β is not a growth factor for lymphocytes; rather in antigen activated immunocompetent cells, blocking IL-1 reduces IL-17 production. IL-1β markedly increases in the expansion of naive and memory CD4T cells in response to challenge with their cognate antigen. The response occurs when only specific CD4T cells respond to IL-1β and not to IL-6 or CD-28. A role for autophagy in production of IL-1β has emerged with deletion of the autophagy gene ATG16L1. Macrophages from ATG16L1-deficient mice produce higher levels of IL-1β after stimulation with TLR4 ligands via a mechanism of caspase-1 activation. The implications for increased IL-1β release in persons with defective autophagy may have clinical importance for disease.
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Affiliation(s)
- Leo A B Joosten
- Department of Internal Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Mihai G Netea
- Department of Internal Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Charles A Dinarello
- Department of Internal Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands; Department of Medicine, University of Colorado Denver, Aurora, CO, USA.
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19
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Nörenberg D, Wieser A, Magistro G, Hoffmann C, Meyer C, Messerer M, Schubert S. Molecular analysis of a novel Toll/interleukin-1 receptor (TIR)-domain containing virulence protein of Y. pseudotuberculosis among Far East scarlet-like fever serotype I strains. Int J Med Microbiol 2013; 303:583-94. [PMID: 24018301 DOI: 10.1016/j.ijmm.2013.08.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 07/29/2013] [Accepted: 08/07/2013] [Indexed: 01/05/2023] Open
Abstract
Pathogenicity of Yersinia pseudotuberculosis is determined by an arsenal of virulence factors. Particularly, the Yersinia outer proteins (Yops) and the Type III secretion system (T3SS) encoded on the pYV virulence plasmid are required for Yersinia pathogenicity. A specific group of Y. pseudotuberculosis, responsible for the clinical syndrome described as Far East scarlet-like fever (FESLF), is known to have an altered virulence gene cluster. Far East strains cause unique clinical symptoms for which the pYV virulence plasmid plays apparently a rather secondary role. Here, we characterize a previously unknown protein of Y. pseudotuberculosis serotype I strains (TcpYI) which can be found particularly among the FESLF strain group. The TcpYI protein shares considerable sequence homology to members of the Toll/IL-1 receptor family. Bacterial TIR domain containing proteins (Tcps) interact with the innate immune system by TIR-TIR interactions and subvert host defenses via individual, multifaceted mechanisms. In terms of virulence, it appears that the TcpYI protein of Y. pseudotuberculosis displays its own virulence phenotype compared to the previously characterized bacterial Tcps. Our results clearly demonstrate that TcpYI increases the intracellular survival of the respective strains in vitro. Furthermore, we show here that the intracellular survival benefit of the wild-type strain correlates with an increase in tcpYI gene expression inside murine macrophages. In support of this, we found that TcpYI enhances the survival inside the spleens of mice in a mouse model of peritonitis. Our results may point toward involvement of the TcpYI protein in inhibition of phagocytosis, particularly in distinct Y. pseudotuberculosis strains of the FESLF strain group where the pYV virulence plasmid is absent.
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Affiliation(s)
- Dominik Nörenberg
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Marchioninistr. 17, D-81377 München, Germany
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20
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Abstract
The discovery of Toll-like receptors (TLRs) was an important event for immunology research and was recognized as such with the awarding of the 2011 Nobel Prize in Physiology or Medicine to Jules Hoffmann and Bruce Beutler, who, together with Ralph Steinman, the third winner of the 2011 Nobel Prize and the person who discovered the dendritic cell, were pioneers in the field of innate immunity. TLRs have a central role in immunity - in this Timeline article, we describe the landmark findings that gave rise to this important field of research.
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21
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Interleukin-1 (IL-1) family of cytokines: role in type 2 diabetes. Clin Chim Acta 2012; 413:1163-70. [PMID: 22521751 DOI: 10.1016/j.cca.2012.03.021] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 03/20/2012] [Accepted: 03/24/2012] [Indexed: 12/17/2022]
Abstract
Cytokines are small cell signaling protein molecules which encompass a large and diverse family. They consist of immunomodulating agents such as interleukins and inteferons. Virtually all nucleated cells, especially endo/epithelial cells and macrophages are potent producers of IL-1, IL-6 and TNF-α. IL-1 family is a group of cytokines which play a central role in the regulation of immune and inflammatory responses. Type 2 diabetes (T2D) has been recognized as an immune mediated disease leading to impaired insulin signaling and selective destruction of insulin producing β-cells in which cytokines play an important role. Disturbance of anti-inflammatory response could be a critical component of the chronic inflammation resulting in T2D. IL-1 family of cytokines has important roles in endocrinology and in the regulation of responses associated with inflammatory stress. The IL-1 family consists of two pro-inflammatory cytokines, IL-1α and IL-1β, and a naturally occurring anti-inflammatory agent, the IL-1 receptor antagonist (IL-1Ra or IL-1RN). This review is an insight into the different types of cytokines belonging to IL-1 family, their modes of action and association with Type 2 diabetes.
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Goh FG, Midwood KS. Intrinsic danger: activation of Toll-like receptors in rheumatoid arthritis. Rheumatology (Oxford) 2011; 51:7-23. [PMID: 21984766 DOI: 10.1093/rheumatology/ker257] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
RA is a debilitating disorder that manifests as chronic localized synovial and systemic inflammation leading to progressive joint destruction. Recent advances in the molecular basis of RA highlight the role of both the innate and adaptive immune system in disease pathogenesis. Specifically, data obtained from in vivo animal models and ex vivo human tissue explants models has confirmed the central role of Toll-like receptors (TLRs) in RA. TLRs are pattern recognition receptors (PRRs) that constitute one of the primary host defence mechanisms against infectious and non-infectious insult. This receptor family is activated by pathogen-associated molecular patterns (PAMPs) and by damage-associated molecular patterns (DAMPs). DAMPs are host-encoded proteins released during tissue injury and cell death that activate TLRs during sterile inflammation. DAMPs are also proposed to drive aberrant stimulation of TLRs in the RA joint resulting in increased expression of cytokines, chemokines and proteases, perpetuating a vicious inflammatory cycle that constitutes the hallmark chronic inflammation of RA. In this review, we discuss the signalling mechanisms of TLRs, the central function of TLRs in the pathogenesis of RA, the role of endogenous danger signals in driving TLR activation within the context of RA and the current preclinical and clinical strategies available to date in therapeutic targeting of TLRs in RA.
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Affiliation(s)
- Fui G Goh
- Kennedy Institute of Rheumatology Division, Matrix Biology Department, Faculty of Medicine, Imperial College of Science, Technology and Medicine, 65 Aspenlea Road, Hammersmith, London W6 8LH, UK
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Gu YF, Fang Y, Jin Y, Dong WR, Xiang LX, Shao JZ. Discovery of the DIGIRR gene from teleost fish: a novel Toll-IL-1 receptor family member serving as a negative regulator of IL-1 signaling. THE JOURNAL OF IMMUNOLOGY 2011; 187:2514-30. [PMID: 21804011 DOI: 10.4049/jimmunol.1003457] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Toll-IL-1R (TIR) family members play crucial roles in a variety of defense, inflammatory, injury, and stress responses. Although they have been widely investigated in mammals, little is known about TIRs in ancient vertebrates. In this study, we report a novel double Ig IL-1R related molecule (DIGIRR) from three model fish (Tetraodon nigroviridis, Gasterosteus aculeatus, and Takifugu rubripes), adding a previously unknown homolog to the TIR family. This DIGIRR molecule contains two Ig-like domains in the extracellular region, one Arg-Tyr-mutated TIR domain in the intracellular region, and a unique subcellular distribution within the Golgi apparatus. These characteristics distinguish DIGIRR from other known family members. In vitro injection of DIGIRR into zebrafish embryos dramatically inhibited LPS-induced and IL-1β-induced NF-κB activation. Moreover, in vivo knockdown of DIGIRR by small interfering RNA significantly promoted the expression of IL-1β-stimulated proinflammatory cytokines (IL-6 and IL-1β) in DIGIRR-silenced liver and kidney tissues and in leukocytes. These results strongly suggest that DIGIRR is an important negative regulator of LPS-mediated and IL-1β-mediated signaling pathways and inflammatory responses. The Arg-Tyr-mutated site disrupted the signal transduction ability of DIGIRR TIR. Evolutionally, we propose a hypothesis that DIGIRR and single Ig IL-1R related molecule (SIGIRR) might originate from a common ancient IL-1R-like molecule that lost one (in DIGIRR) or two (in SIGIRR) extracellular Ig-like domains and intracellular Ser and Arg-Tyr amino acids. DIGIRR might be an evolutionary "transitional molecule" between IL-1R and SIGIRR, representing a shift from a potent receptor to a negative regulator. These results help define the evolutionary history of TIR family members and their associated signaling pathways and mechanisms.
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Affiliation(s)
- Yi-feng Gu
- College of Life Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China
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24
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Abstract
An expanding spectrum of acute and chronic inflammatory diseases is considered 'autoinflammatory' diseases. This review considers autoinflammatory diseases as being distinct from 'autoimmune' diseases. Autoimmune diseases are associated with dysfunctional T cells and treated with 'biologicals', including antitumour necrosis factorα, CTLA-Ig, anti-IL-12/23, anti-CD20, anti-IL-17 and anti-IL-6 receptor. In contrast, autoinflammatory diseases are uniquely attributed to a dysfunctional monocyte caspase 1 activity and secretion of IL-1β; indeed, blocking IL-1β results in a rapid and sustained reduction in the severity of most autoinflammatory diseases. Flares of gout, type 2 diabetes, heart failure and smouldering multiple myeloma are examples of seemingly unrelated diseases, which are uniquely responsive to IL 1β neutralization.
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Affiliation(s)
- C A Dinarello
- Department of Medicine, University of Colorado, Aurora, CO, USA.
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25
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Cloning and characterization of type II interleukin-1 receptor cDNA from Japanese flounder (Paralichthys olivaceus). Comp Biochem Physiol B Biochem Mol Biol 2010; 157:59-65. [DOI: 10.1016/j.cbpb.2010.05.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 04/30/2010] [Accepted: 05/03/2010] [Indexed: 11/23/2022]
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Abstract
Although there has been a great amount of progress in the 25 years since the first reporting of the cDNA for IL-1alpha and IL-1beta, the history of IL-1 goes back to the early 1940s. In fact, the entire field of inflammatory cytokines, TLR and the innate immune response can be found in the story of IL-1. This Viewpoint follows the steps from the identification of the fever-inducing activities of "soluble factors" produced by endotoxin-stimulated leukocytes through to the discovery of cryopyrin and the caspase-1 inflammasome and on to the clinical benefits of anti-IL-1beta-based therapeutics. It also discusses some of the current controversies regarding the activation of the inflammasome. The future of novel anti-inflammatory agents to combat chronic inflammation is based, in part, on the diseases that are uniquely responsive to anti-IL-1beta, which is surely a reason to celebrate the 25th anniversary of the cloning of IL-1alpha and IL-1beta.
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Affiliation(s)
- Charles A Dinarello
- Department of Medicine, University of Colorado Denver, Aurora, CO 80045, USA.
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Gopal R, Birdsell D, Monroy FP. Regulation of toll-like receptors in intestinal epithelial cells by stress and Toxoplasma gondii infection. Parasite Immunol 2009; 30:563-76. [PMID: 19067837 DOI: 10.1111/j.1365-3024.2008.01055.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intestinal epithelial cells (IECs) form a barrier between invading microorganisms and the underlying host tissues. IECs express toll-like receptors (TLRs) that recognize specific molecular signatures on microbes, which activate intracellular signalling pathways leading to production of proinflammatory cytokines and chemokines. Stress hormones play an important role in modulation of proinflammatory cytokines and down-regulation of immune responses. Here we demonstrated that expression levels of TLR-2, TLR-4, TLR-9 and TLR-11 were significantly increased in mouse IECs following infection with Toxoplasma gondii on day 8 postinfection. In contrast, expression of TLRs was significantly decreased in infected mice subjected to cold water stress (CWS + INF). Expression of TLR-9 and TLR-11 in the mouse MODE-K cell line was significantly increased after infection. Expression of TLR-9 and TLR-11 in cells exposed to norepinephrine (NE) and parasites was significantly decreased when compared to cells exposed to parasites only. A significant increase was observed in SIGIRR, a negative regulator of TLRs in the CWS + INF group when compared to the INF group. Stress components were able to decrease expression levels of TLRs in IECs, decrease parasite load, and increase expression of a negative regulator thereby ameliorating intestinal inflammatory responses commonly observed during per oral T. gondii infection in C57BL/6 mice.
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Affiliation(s)
- R Gopal
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
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28
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Dahlén E, Barchan K, Herrlander D, Höjman P, Karlsson M, Ljung L, Andersson M, Bäckman E, Hager ACM, Walse B, Joosten L, van den Berg W. Development of Interleukin-1 Receptor Antagonist Mutants with Enhanced Antagonistic ActivityIn Vitroand Improved Therapeutic Efficacy in Collagen-Induced Arthritis. J Immunotoxicol 2008; 5:189-99. [DOI: 10.1080/15476910802131477] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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Abstract
The ten human Toll-like receptors are able to respond to an extremely diverse range of microbial products ranging from di- and tri-acylated lipids to nucleic acids. An understanding of the molecular structure adopted by the receptor extracellular, transmembrane, and cytoplasmic domains and the way in which these structures interact with ligands and downstream signaling adapters can explain how recognition and signal transduction are achieved at a molecular level. In this article we discuss how the leucine-rich repeats of the receptor ectodomain have evolved to bind a wide variety of biological molecules. We also discuss how ligand binding induces dimerization of two receptor chains and initiates a series of protein conformational changes that lead to a signaling event in the cytoplasm of the immune system cell. Thus, the signaling process of the TLRs can be viewed as a unidirectional molecular switch.
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Know thy Sef: A novel class of feedback antagonists of receptor tyrosine kinase signaling. Int J Biochem Cell Biol 2008; 40:2040-52. [DOI: 10.1016/j.biocel.2008.03.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Revised: 03/06/2008] [Accepted: 03/06/2008] [Indexed: 02/06/2023]
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31
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Moon SK, Woo JI, Lee HY, Park R, Shimada J, Pan H, Gellibolian R, Lim DJ. Toll-like receptor 2-dependent NF-kappaB activation is involved in nontypeable Haemophilus influenzae-induced monocyte chemotactic protein 1 up-regulation in the spiral ligament fibrocytes of the inner ear. Infect Immun 2007; 75:3361-72. [PMID: 17452470 PMCID: PMC1932924 DOI: 10.1128/iai.01886-06] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Inner ear dysfunction secondary to chronic otitis media (OM), including high-frequency sensorineural hearing loss or vertigo, is not uncommon. Although chronic middle ear inflammation is believed to cause inner ear dysfunction by entry of OM pathogen components or cytokines from the middle ear into the inner ear, the underlying mechanisms are not well understood. Previously, we demonstrated that the spiral ligament fibrocyte (SLF) cell line up-regulates monocyte chemotactic protein 1 (MCP-1) expression after treatment with nontypeable Haemophilus influenzae (NTHI), one of the most common OM pathogens. We hypothesized that the SLF-derived MCP-1 plays a role in inner ear inflammation secondary to OM that is responsible for hearing loss and dizziness. The purpose of this study was to investigate the signaling pathway involved in NTHI-induced MCP-1 up-regulation in SLFs. Here we show for the first time that NTHI induces MCP-1 up-regulation in the SLFs via Toll-like receptor 2 (TLR2)-dependent activation of NF-kappaB. TLR2(-/-)- and MyD88(-/-)-derived SLFs revealed involvement of TLR2 and MyD88 in NTHI-induced MCP-1 up-regulation. Studies using chemical inhibitors and dominant-negative constructs demonstrated that it is mediated by the IkappaKbeta-dependent IkappaBalpha phosphorylation and NTHI-induced NF-kappaB nuclear translocation. Furthermore, we demonstrated that the binding of NF-kappaB to the enhancer region of MCP-1 is involved in this up-regulation. In addition, we have identified a potential NF-kappaB motif that is responsive and specific to certain NTHI molecules or ligands. Further studies are necessary to reveal specific ligands of NTHI that activate host receptors. These results may provide us with new therapeutic strategies for prevention of inner ear dysfunction secondary to chronic middle ear inflammation.
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Affiliation(s)
- Sung K Moon
- The Gonda Department of Cell and Molecular Biology, House Ear Institute, 2100 West 3rd Street, Los Angeles, CA 90057, USA
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Takagi M, Tamaki Y, Hasegawa H, Takakubo Y, Konttinen L, Tiainen VM, Lappalainen R, Konttinen YT, Salo J. Toll-like receptors in the interface membrane around loosening total hip replacement implants. J Biomed Mater Res A 2007; 81:1017-26. [PMID: 17415764 DOI: 10.1002/jbm.a.31235] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Toll-like receptors (TLRs) have been known to act as sensors of innate immunity and respond to ligands of microbial and endogenous components. Tissues and cells typical for interface membrane of foreign body reaction were analyzed to evaluate potential role of TLRs in the pathogenesis of the so called "aseptic loosening of total hip replacement." Fourteen cases of interface membrane around aseptic loose total hip replacement implants were stained by single and double immunohistochemical methods to examine cellular localization of toll-like receptor (TLR)-4 and TLR-9. Osteoarthritic synovium was used as control tissues. Cultured macrophages were used to study TLR-4 and TLR-9 mRNA levels by quantitative reverse transcriptase-polymerase chain reaction. The effect of titanium particle stimulation on macrophages was also examined in the culture. Extensive immunolocalization of TLR-4 and TLR-9 positive cells was observed in the synovial membrane-like interface membrane of foreign body granulomas compared with control synovial membranes. TLR and CD68 double staining demonstrated that the TLR positive cells in aseptic loosening were mostly monocyte/macrophages and foreign body giant cells. TLR-4 and TLR-9 mRNA expression was also found in macrophage-colony stimulating factor treated rat macrophages, but this expression decreased (p < 0.05 or less) upon stimulation with titanium particles although matrix metalloproteinase (MMP)-9 mRNA levels used as macrophage activation marker were increased (p = 0.01). The interface membrane around loosening total hip replacement implants is apparently well equipped with TLRs and, thus, probably very sensitive to various structural components of microbes and to endogenous TLR ligands. This seems to be due to recruitment of monocyte/macrophages as particles per se seemed to down-regulate some of the key TLRs. This suppression after particle phagocytosis might prevent excessive and harmful host responses, and injury to innocent bystander cells/tissues.
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Affiliation(s)
- Michiaki Takagi
- Department of Orthopaedic Surgery, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
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33
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Böl GF, Jurrmann N, Brigelius-Flohé R. Cellular trafficking of the IL-1RI-associated kinase-1 requires intact kinase activity. Biochem Biophys Res Commun 2005; 332:279-87. [PMID: 15896328 DOI: 10.1016/j.bbrc.2005.04.121] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Accepted: 04/23/2005] [Indexed: 10/25/2022]
Abstract
Upon stimulation of cells with interleukin-1 (IL-1) the IL-1 receptor type I (IL-1RI) associated kinase-1 (IRAK-1) transiently associates to and dissociates from the IL-1RI and thereafter translocates into the nucleus. Here we show that nuclear translocation of IRAK-1 depends on its kinase activity since translocation was not observed in EL-4 cells overexpressing a kinase negative IRAK-1 mutant (EL-4(IRAK-1-K239S)). IRAK-1 itself, an endogenous substrate with an apparent molecular weight of 24kDa (p24), and exogenous substrates like histone and myelin basic protein are phosphorylated by nuclear located IRAK-1. Phosphorylation of p24 cannot be detected in EL-4(IRAK-1-K239S) cells. IL-1-dependent recruitment of IRAK-1 to the IL-1RI and subsequent phosphorylation of IRAK-1 is a prerequisite for nuclear translocation of IRAK-1. It is therefore concluded that intracellular localization of IRAK-1 depends on its kinase activity and that IRAK-1 may also function as a kinase in the nucleus as shown by a new putative endogenous substrate.
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Affiliation(s)
- Gaby-Fleur Böl
- German Institute of Human Nutrition Potsdam-Rehbruecke, Biochemistry of Micronutrients, 14558 Nuthetal, Germany.
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Pålsson-McDermott EM, O'Neill LAJ. Signal transduction by the lipopolysaccharide receptor, Toll-like receptor-4. Immunology 2004; 113:153-62. [PMID: 15379975 PMCID: PMC1782563 DOI: 10.1111/j.1365-2567.2004.01976.x] [Citation(s) in RCA: 899] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
An understanding of lipopolysaccharide (LPS) signal transduction is a key goal in the effort to provide a molecular basis for the lethal effect of LPS during septic shock and point the way to novel therapies. Rapid progress in this field during the last 6 years has resulted in the discovery of not only the receptor for LPS - Toll-like receptor 4 (TLR4) - but also in a better appreciation of the complexity of the signalling pathways activated by LPS. Soon after the discovery of TLR4, the formation of a receptor complex in response to LPS, consisting of dimerized TLR4 and MD-2, was described. Intracellular events following the formation of this receptor complex depend on different sets of adapters. An early response, which is dependent on MyD88 and MyD88-like adapter (Mal), leads to the activation of nuclear factor-kappaB (NF-kappaB). A later response to LPS makes use of TIR-domain-containing adapter-inducing interferon-beta (TRIF) and TRIF-related adapter molecule (TRAM), and leads to the late activation of NF-kappaB and IRF3, and to the induction of cytokines, chemokines, and other transcription factors. As LPS signal transduction is an area of intense research and rapid progress, this review is intended to sum up our present understanding of the events following LPS binding to TLR4, and we also attempt to create a model of the signalling pathways activated by LPS.
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35
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Affiliation(s)
- Bruno Lemaitre
- Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, F-91198 Gif-sur-Yvette, France.
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36
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Abstract
Vaccination with Borrelia burgdorferi outer surface protein (Osp) A can induce a protective response against Lyme disease and serves as a model to understand the generation of protective immune responses against the spirochete. The innate response to pathogens is activated by specific Toll-like receptors (TLRs) that recognize distinct pathogen-associated molecular patterns. TLR2 is of particular interest for B. burgdorferi research because TLR2 recognizes several pathogen-associated molecular patterns, including lipoproteins. TLR2 may form heterodimers with TLR6 to identify diacylated lipoproteins, while TLR2 works in concert with TLR1 to recognize triacylated lipoproteins such as OspA. We will discuss the role of TLR1/2 in the development of responses to OspA in TLR1-and TLR2-deficient mice, and in selected individuals that received the OspA vaccine. While > 95% of human OspA-based Lyme disease vaccine recipients develop OspA antibodies, a very small group of individuals did not develop detectable humoral responses against OspA. We demonstrated that this hyporesponsiveness to OspA vaccination was associated with decreased cell surface expression of TLR1. Moreover, TLR1- and TLR2-deficient mice did not develop significant levels of OspA antibodies following vaccination with OspA, providing a correlation with human hyporesponsiveness to OspA. These data suggest that defects in the TLR1/2 signaling pathway are associated with an impaired ability to generate antibodies following immunization with OspA lipoprotein.
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Affiliation(s)
- Venetta Thomas
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8031, USA
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Farnell MB, He H, Genovese K, Kogut MH. Pharmacological analysis of signal transduction pathways required for oxidative burst in chicken heterophils stimulated by a Toll-like receptor 2 agonist. Int Immunopharmacol 2003; 3:1677-84. [PMID: 14555292 DOI: 10.1016/s1567-5769(03)00205-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Toll-like receptors (TLRs) play an important role in the innate immune response of avian heterophils. We previously used the pharmacological inhibitors genistein, verapamil, chelerythrine, and pertussis toxin to investigate the upstream signaling events involved in TLR2-mediated oxidative burst in chicken heterophils. Only chelerythrine, a protein kinase C inhibitor, was found to significantly inhibit oxidative burst stimulated by the TLR2 agonist lipoteichoic acid (LTA). In the present study, we used selective pharmacological inhibitors to investigate the roles of phosphatidylinositol-3'-kinase (PI3-K), phospholipase C (PLC), calcium-dependent protein kinase C (PKC), extra-cellular signal regulated kinase (ERK), and nuclear translocation factor kappa B (NF-kappaB) on TLR2-mediated oxidative burst. U-73122 (a PLC inhibitor), wortmannin (a PI3-K inhibitor), PD 98059 (an ERK inhibitor), Gö 6976 (a PKC inhibitor) and Bay 11-7082 (a NF-kappaB inhibitor) significantly decreased LTA-stimulated oxidative burst in heterophils by 77%, 30%, 36%, 78%, and 61%, respectively. Activated TLR2 utilizes PI3-K, PLC, PKC, ERK, and NF-kappaB as signaling factors that mediate the oxidative burst of chicken heterophils.
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Affiliation(s)
- Morgan B Farnell
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4467, USA
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Li X, Tupper JC, Bannerman DD, Winn RK, Rhodes CJ, Harlan JM. Phosphoinositide 3 kinase mediates Toll-like receptor 4-induced activation of NF-kappa B in endothelial cells. Infect Immun 2003; 71:4414-20. [PMID: 12874320 PMCID: PMC166052 DOI: 10.1128/iai.71.8.4414-4420.2003] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many of the proinflammatory effects of gram-negative bacteria are elicited by the interaction of bacterial lipopolysaccharide (LPS) with Toll-like receptor 4 (TLR4) expressed on host cells. TLR4 signaling leads to activation of NF-kappa B and transcription of many genes involved in the inflammatory response. In this study, we examined the signaling pathways involved in NF-kappa B activation by TLR4 signaling in human microvascular endothelial cells. Akt is a major downstream target of phosphoinositide 3 kinase (PI3-kinase), and PI3-kinase activation is necessary and sufficient for Akt phosphorylation. Consequently, Akt kinase activation was used as a measure of PI3-kinase activity. In a stable transfection system, dominant-negative mutants of myeloid differentiation factor 88 (MyD88) and interleukin-1 (IL-1) receptor-associated kinase 1 (IRAK-1) (MyD88-TIR and IRAK-DD, respectively) blocked Akt kinase activity in response to LPS and IL-1 beta. A dominant-negative mutant (Mal-P/H) of MyD88 adapter-like protein (Mal), a protein with homology to MyD88, failed to inhibit LPS- or IL-1 beta-induced Akt activity. Moreover, a dominant-negative mutant of p85 (p85-DN) inhibited the NF-kappa B luciferase activity, IL-6 production, and I kappa B alpha degradation elicited by LPS and IL-1 beta but not that stimulated by tumor necrosis factor alpha. The dominant-negative mutant of Akt partially inhibited the NF-kappa B luciferase activity evoked by LPS and IL-1 beta. However, expression of a constitutively activated Akt failed to induce NF-kappa B luciferase activity. These findings indicate that TLR4- and IL-1R-induced PI3-kinase activity is mediated by the adapter proteins MyD88 and IRAK-1 but not Mal. Further, these studies suggest that PI3-kinase is an important mediator of LPS and IL-1 beta signaling leading to NF-kappa B activation in endothelial cells and that Akt is necessary but not sufficient for NF-kappa B activation by TLR4.
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Affiliation(s)
- Xianwu Li
- Department of Medicine, University of Washington, Seattle, Washington 98195, USA
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Novatchkova M, Leibbrandt A, Werzowa J, Neubüser A, Eisenhaber F. The STIR-domain superfamily in signal transduction, development and immunity. Trends Biochem Sci 2003; 28:226-9. [PMID: 12765832 DOI: 10.1016/s0968-0004(03)00067-7] [Citation(s) in RCA: 199] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We have identified a conserved sequence segment in transmembrane receptors (including SEFs, IL17Rs) and soluble factors (including CIKS/ACT1) in eukaryotes and bacteria - the SEFIR domain. This sequence domain is part of the new STIR domain superfamily comprising also the TIR domain known to mediate TIR-TIR homotypic interactions. In TOLL/IL1R-like pathways, the cytoplasmically localized TIR domain of a receptor and the TIR domain of a soluble adaptor interact physically and activate signalling. The similarity between the SEFIR and TIR domains involves the conserved boxes 1 and 2 of the TIR domain that are implicated in homotypic dimerization, but there is no sequence similarity between SEFIR domains and the TIR sequence box 3. By analogy, we suggest that SEFIR-domain proteins function as signalling components of Toll/IL-1R-similar pathways and that their SEFIR domain mediates physical protein-protein interactions between pathway components.
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Affiliation(s)
- Maria Novatchkova
- Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria.
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Ronni T, Agarwal V, Haykinson M, Haberland ME, Cheng G, Smale ST. Common interaction surfaces of the toll-like receptor 4 cytoplasmic domain stimulate multiple nuclear targets. Mol Cell Biol 2003; 23:2543-55. [PMID: 12640135 PMCID: PMC150739 DOI: 10.1128/mcb.23.7.2543-2555.2003] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Toll-like receptor 4 (TLR4) mediates the host response to lipopolysaccharide (LPS) by promoting the activation of pro- and anti-inflammatory cytokine genes. To activate each gene, numerous signal transduction pathways are required. The adaptor proteins MyD88 and TIRAP contribute to the activation of several and possibly all pathways via direct interactions with TLR4's Toll/interleukin-1 receptor (IL-1R) (TIR) domain. However, additional adaptors that are required for the activation of specific subsets of pathways may exist, which could contribute to the differential regulation of target genes. Furthermore, it remains unknown whether direct interactions that have been reported between TIR domains and other proteins are required for TLR4 signaling. To address these issues, we systematically mutated the TLR4 TIR domain in the context of a CD4/TLR4 fusion protein. Several exposed residues defining at least two structural surfaces were required in macrophages for activation of the proinflammatory IL-12 p40 and anti-inflammatory IL-10 promoters, as well as promoters dependent on individual transcription factors. Interestingly, the same residues were required by all promoters tested, suggesting that the signaling pathways diverge downstream of the adaptors. The mutant phenotypes provide a framework for future studies of TLR4 signaling, as the interaction supported by each critical surface residue will need to be defined.
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Affiliation(s)
- Tapani Ronni
- Howard Hughes Medical Institute and Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, California 90095, USA
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Dunne A, O'Neill LAJ. The Interleukin-1 Receptor/Toll-Like Receptor Superfamily: Signal Transduction During Inflammation and Host Defense. Sci Signal 2003. [DOI: 10.1126/scisignal.1712003re3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Dunne A, O'Neill LAJ. The interleukin-1 receptor/Toll-like receptor superfamily: signal transduction during inflammation and host defense. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2003; 2003:re3. [PMID: 12606705 DOI: 10.1126/stke.2003.171.re3] [Citation(s) in RCA: 347] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The signal transduction pathways activated by the proinflammatory cytokine interleukin-1 (IL-1) have been the focus of much attention because of the important role that IL-1 plays in inflammatory diseases. A number of proteins have been described that participate in the post-receptor activation of the transcription factor nuclear factor kappaB (NF-kappaB), and stress-activated protein kinases such as p38 mitogen-activated protein kinase (MAPK). It has also emerged that the type I IL-1 receptor (IL-1RI) is a member of an expanding receptor superfamily. These related receptors all have sequence similarity in their cytosolic regions. The family includes the Drosophila melanogaster protein Toll, the IL-18 receptor (IL-18R), and 10 Toll-like receptors (TLRs), TLR-1 to TLR-10, which bind to microbial products, activating host defense responses. Because of the similarity of IL-1RI to Toll, the conserved sequence in the cytosolic region of these proteins has been termed the Toll-IL-1 receptor (TIR) domain. The same proteins activated during signaling by IL-1RI also participate in signaling by other receptors with TIR domains. The receptor superfamily is evolutionarily conserved; members also occur in plants and insects, where they also function in host defense. The signaling proteins that are activated are also conserved across species. Differences are, however, starting to emerge in signaling pathways activated by different receptors. This receptor superfamily, therefore, represents an ancient signaling system that is a critical determinant of the innate immune and inflammatory responses.
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Affiliation(s)
- Aisling Dunne
- Department of Biochemistry and Biotechnology Institute, Trinity College, Dublin, Ireland
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O'Neill LAJ. Signal transduction pathways activated by the IL-1 receptor/toll-like receptor superfamily. Curr Top Microbiol Immunol 2003. [PMID: 12467243 DOI: 10.1007/978-3-642-59430-4_3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Toll-like receptors (TLRs) are an important point of first contact between host and microbe, and once activated generate signals which culminate in the induction of genes important for host defence. TLRs respond to different microbial products, and the signalling pathways activated are very similar to that generated by the pro-inflammatory cytokine interleukin-1 (IL-1). This is because the Type I IL-1 receptor and TLRs are highly homologous in their cytosolic portions, possessing a Toll/IL-1 receptor (TIR) domain. Signals triggered include the important transcription factor NF-kappa B and two MAP kinases, p38 and Jun N-terminal kinase. Receptor-proximal proteins involved include the adapter MyD88, IRAK, IRAK-2, Tollip, TRAF6 and TAK-1. These latter two proteins need to be ubiquitinated in order to be active. Differences between signals generated by TLRs are emerging, with TLR-4 signalling requiring an additional adapter termed MyD88-adapter-like (Mal), which may regulate the expression of genes specific for the response required to eliminate infection by Gram-negative bacteria. Future studies on TLR signalling may reveal hitherto unsuspected specificities in the innate immune response to infection.
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Affiliation(s)
- L A J O'Neill
- Department of Biochemistry, Trinity College Dublin, Ireland.
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Subramaniam S, Stansberg C, Olsen L, Zou J, Secombes CJ, Cunningham C. Cloning of a Salmo salar interleukin-1 receptor-like cDNA. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2002; 26:415-431. [PMID: 11906722 DOI: 10.1016/s0145-305x(01)00091-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The interleukin-1 receptor/toll-like receptor (IL-1R/TLR) superfamily, defined by a cytosolic Toll/IL-1R (TIR) signalling domain, participates in host responses to injury and infection. We describe in this study the cloning of a cDNA encoding a Salmo salar interleukin-1 receptor-like protein (SalIL-1RLP). SalIL-1RLP comprises a potential signal peptide, three extracellular immunoglobulin domains, a short transmembrane region and an intracellular region that contains the TIR domain. The predicted amino acid sequence of SalIL-1RLP displays 43-44% similarities and 31% identities to chicken and human IL-1RI sequences. Within the intracellular region, SalIL-1RLP displays highest similarity (59%) and identity (46%) to the chicken IL-1RI sequence. Two different 5' distal UTRs were identified among six salmon IL-1RLP clones. The six clones, however, displayed identical 5' proximal UTRs, coding regions and 3' UTRs. SalIL-1RLP expression is induced in liver, head kidney, spleen and gills upon injection of salmon with bacterial lipopolysaccharide. Sequence comparisons, protein domain structures, expression patterns and phylogenetic analyses indicate that SalIL-1RLP is most closely related to type I interleukin-1 receptors and interleukin-1 receptor related proteins.
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Affiliation(s)
- Sumathi Subramaniam
- Sars International Centre for Marine Molecular Biology, Bergen High Technology Centre, Thormøhlensgt. 55, N-5008 Bergen, Norway
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Nicklin MJH, Barton JL, Nguyen M, FitzGerald MG, Duff GW, Kornman K. A sequence-based map of the nine genes of the human interleukin-1 cluster. Genomics 2002; 79:718-25. [PMID: 11991722 DOI: 10.1006/geno.2002.6751] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Six novel genes encoding proteins with the interleukin (IL)-1 fold have been identified recently. The classical family members are involved in inflammatory signaling. Previous work has placed the novel genes close to or within the same cluster as IL1A, IL1B, and IL1RN, which occupy an approximately 400-kb interval on chromosome 2. We have combined the incomplete public database sequence with our own sequence to generate a reference sequence and map that encompass all of the novel genes, allowing determination of the gene structures, precise localization of exons, and determination of distances between conventional SNP and microsatellite markers. Gene order from centromere to telomere is IL1A-IL1B-IL1F7-IL1F9-IL1F6-IL1F8-IL1F5-IL1F10-IL1RN, of which only IL1A, IL1B, and IL1F8 are transcribed towards the centromere. The gene order relates to the evolutionary relationship between the genes. Key features of exon boundaries are conserved. There is no evidence for other IL-1 family members within the cluster.
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Affiliation(s)
- Martin J H Nicklin
- Division of Genomic Medicine, University of Sheffield, Royal Hallamshire Hospital, Sheffield S10 2JF, UK.
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Netea MG, Kullberg BJ, Galama JMD, Stalenhoef AFH, Dinarello CA, Van der Meer JWM. Non-LPS components of Chlamydia pneumoniae stimulate cytokine production through Toll-like receptor 2-dependent pathways. Eur J Immunol 2002; 32:1188-95. [PMID: 11932927 DOI: 10.1002/1521-4141(200204)32:4<1188::aid-immu1188>3.0.co;2-a] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Recent studies suggest that infection with Chlamydia pneumoniae is associated with atherosclerosis, and that cytokines play an important role in the initiation and progression of Chlamydia-induced inflammation. When freshly isolated peripheral blood mononuclear cells (PBMC) were stimulated for 24 h with sonicated C. pneumoniae, significant amounts of the pro-inflammatory cytokines TNF-alpha and IL-1beta and of the anti-inflammatory cytokine IL-10 were released into the supernatant. The addition of serum increased cytokine release induced by C. pneumonia two- to fivefold (p < 0.01). This effect was not due to complement, mannose-binding lectin (MBL) or lipopolysaccharide-binding protein (LBP). Incubation of PBMC with either anti-Toll-like receptor 4 (TLR4) or anti-CD14 blocking antibodies did not influence the production of cytokines induced by Chlamydia. The induction of cytokines by C. pneumoniae in macrophages from C3H / HeJ mice, known to have a defective TLR4, was identical to that measured in control macrophages from C3H / HeN mice. In contrast, incubation of PBMC with an anti-TLR2 blocking antibody significantly inhibited the production of TNF by 67 % and of IL-1beta by 72 %. In conclusion, C. pneumoniae stimulates cytokine production in a serum-dependent manner, but independently of complement, MBL and LBP. C. pneumoniae induces the pro-inflammatory cytokines TNF and IL-1beta through TLR2, but not TLR4 and CD14.
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MESH Headings
- Acute-Phase Proteins
- Adult
- Animals
- Carrier Proteins/genetics
- Carrier Proteins/physiology
- Cells, Cultured/drug effects
- Cells, Cultured/metabolism
- Chlamydophila pneumoniae/chemistry
- Chlamydophila pneumoniae/physiology
- Cytokines/biosynthesis
- Cytokines/genetics
- Drosophila Proteins
- Gene Expression Regulation
- Humans
- Interleukin-1/biosynthesis
- Interleukin-1/genetics
- Interleukin-10/biosynthesis
- Interleukin-10/genetics
- Leukocytes, Mononuclear/metabolism
- Lipopolysaccharide Receptors/physiology
- Macrophages, Peritoneal/physiology
- Membrane Glycoproteins/deficiency
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/physiology
- Mice
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Mice, Knockout
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Sonication
- Specific Pathogen-Free Organisms
- Toll-Like Receptor 2
- Toll-Like Receptor 4
- Toll-Like Receptors
- Tumor Necrosis Factor-alpha/biosynthesis
- Tumor Necrosis Factor-alpha/genetics
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Affiliation(s)
- Mihai G Netea
- Department of Medicine, University Medical Center St. Radboud, Nijmegen, The Netherlands.
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Abstract
The Toll-like receptors are the primary sensors of the innate immune system. This assignment of function was predicated on positional cloning, and was the result of long and painstaking inquiry into the mechanism of responses to bacterial endotoxin, the abundant lipopolysaccharide component of the outer membrane of Gram-negative bacteria. The sequence of events that led to the discovery of Toll-like receptor function carries an important lesson that should guide further analysis of the innate immune system.
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Affiliation(s)
- Bruce Beutler
- Scripps Research Institute, La Jolla, California 92037, USA.
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Affiliation(s)
- S Akira
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University.
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Martin M, Katz J, Vogel SN, Michalek SM. Differential induction of endotoxin tolerance by lipopolysaccharides derived from Porphyromonas gingivalis and Escherichia coli. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:5278-85. [PMID: 11673543 DOI: 10.4049/jimmunol.167.9.5278] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Exposure of mononuclear phagocytes to enterobacterial LPS induces a state of transient hyporesponsiveness to subsequent LPS exposure, termed endotoxin tolerance. In the present study, LPS derived from the oral periodontal pathogen, Porphyromonas gingivalis, was compared with that derived from the enterobacterium, Escherichia coli, for the ability to induce endotoxin tolerance. Pretreatment of the human macrophage cell line, THP-1, with E. coli LPS resulted in a severe reduction in the levels of IL-1beta, IL-6, and TNF-alpha upon secondary stimulation. In contrast, pretreatment of THP-1 cells with P. gingivalis LPS resulted in a mitigation of IL-1beta, but not IL-6 and TNF-alpha production upon subsequent exposure to P. gingivalis LPS: primary or secondary stimulation with < or =100 ng/ml P. gingivalis LPS resulted in comparable levels of IL-6 and TNF-alpha, while stimulation of THP-1 cells with > or =1 microg/ml P. gingivalis LPS induced a significant enhancement in IL-6 and TNF-alpha levels upon secondary exposure. To identify possible mechanisms for these differences, changes in the expression of molecules involved in the LPS-signaling pathway were assessed. Pretreatment of THP-1 cells with E. coli LPS resulted in a significant reduction in surface Toll-like receptor 4 (TLR4) expression and an inability to degrade I-kappaB-alpha or I-kappaB-beta proteins upon secondary stimulation. In contrast, pretreatment of THP-1 cells with P. gingivalis LPS resulted in a significant enhancement of both CD14 and TLR2, while maintaining the ability to degrade I-kappaB-beta only upon secondary stimulation. Thus, E. coli and P. gingivalis LPS differentially affect CD14 and TLR expression as well as secondary LPS-associated responses.
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Affiliation(s)
- M Martin
- Department of Microbiology and Oral Biology, University of Alabama, Birmingham, AL 35294, USA
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Moors MA, Li L, Mizel SB. Activation of interleukin-1 receptor-associated kinase by gram-negative flagellin. Infect Immun 2001; 69:4424-9. [PMID: 11401982 PMCID: PMC98515 DOI: 10.1128/iai.69.7.4424-4429.2001] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Flagellin from various species of gram-negative bacteria activates monocytes to produce proinflammatory cytokines. We have analyzed the pathway by which Salmonella enteritidis flagellin (FliC) activates murine and human monocyte/macrophage-like cell lines. Since lipopolysaccharide (LPS), the principal immune stimulatory component of gram-negative bacteria, is known to signal through Toll-like receptor 4 (TLR4), we tested the possibility that FliC also signals via TLR4. When murine HeNC2 cells were stimulated with LPS in the presence of a neutralizing anti-TLR4 monoclonal antibody, tumor necrosis factor alpha (TNF-alpha) and nitric oxide (NO) production were markedly reduced. In contrast, FliC-mediated TNF-alpha and NO production were minimally affected by the anti-TLR4 antibody. Furthermore, FliC, unlike LPS, stimulated TNF-alpha production in the TLR4 mutant cell line, GG2EE, indicating that TLR4 is not essential for FliC-mediated signaling. To test the possibility that FliC signals via another TLR, we measured FliC-mediated activation of interleukin-1 (IL-1) receptor-associated kinase (IRAK), a central component in IL-1R/TLR signaling. FliC induced IRAK activation in HeNC2 and GG2EE cells as well as in the human promonocytic cell line THP-1. IRAK activation was rapid in HeNC2 cells, with maximal activity observed after 5 min of treatment with FliC. In addition, FliC-mediated IRAK activation exhibited the same concentration dependence as was demonstrated for the induction of TNF-alpha. These results represent the first demonstration of IRAK activation by a purified bacterial protein and strongly suggest that a TLR distinct from TLR4 is involved in the macrophage inflammatory response to FliC.
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Affiliation(s)
- M A Moors
- Department of Microbiology and Immunology, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA
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