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Kusumoto S, Fukase K, Shiba T. Key structures of bacterial peptidoglycan and lipopolysaccharide triggering the innate immune system of higher animals: chemical synthesis and functional studies. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2010; 86:322-337. [PMID: 20431259 PMCID: PMC3417798 DOI: 10.2183/pjab.86.322] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Accepted: 03/03/2010] [Indexed: 05/29/2023]
Abstract
Chemistry-based investigation is reviewed which led to identification of the active entities responsible for the immunostimulating potencies of peptidoglycan and lipopolysaccharide. Though these glycoconjugates which ubiquitously occur in wide range of bacteria as the essential components of their cell envelopes have long been known to enhance the immunological responses of higher animals, neither the precise chemical structures required nor the mechanism of their action had been [corrected] elucidated until early 1970s. Chemical synthesis of partial structures of peptidoglycan proved N-acetylmuramyl-L-alanyl-D-isoglutamine to be the minimum structure responsible for the activity and led to later identification of its receptor protein Nod2 present in animal cells. Another active partial structure of peptidoglycan, gamma-D-glutamyl-meso-diaminopimelic acid, and its receptor Nod1 were also identified as well. With regard to lipopolysaccharide, its glycolipid part named lipid A was purified and the structure studied. Chemically synthesized lipid A according to the newly elucidated structure exhibited full activity described for lipopolysaccharide known as endotoxin. Synthetic homogeneous lipid A and its structural analogues and labeled derivatives enabled precise studies of their interaction with receptor proteins and the mechanism of their action. Chemical synthesis of homogeneous partial structures of peptidoglycan and lipopolysaccharide gave unequivocal evidences for the concept that definite small molecular parts of these complex macromolecular bacterial glycoconjugates are specifically recognized by their respective receptors and trigger our defense system now widely recognized as innate immunity.
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Affiliation(s)
- Shoichi Kusumoto
- Suntory Institute for Bioorganic Research, Wakayamadai 1-1-1, Shimamotocho, Osaka, Japan.
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202
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Cipolla L, Gabrielli L, Bini D, Russo L, Shaikh N. Kdo: a critical monosaccharide for bacteria viability. Nat Prod Rep 2010; 27:1618-29. [DOI: 10.1039/c004750n] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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203
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Sawyer K, Mundandhara S, Ghio AJ, Madden MC. The effects of ambient particulate matter on human alveolar macrophage oxidative and inflammatory responses. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2010; 73:41-57. [PMID: 19953419 DOI: 10.1080/15287390903248901] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Epidemiologic and occupational studies demonstrated that ambient particulate matter (PM) and diesel exhaust particles (DEP) exert deleterious effects on human cardiopulmonary health, including exacerbation of pre-existing lung disease and development of respiratory infections. The effects of ambient PM on lung cell responsiveness are poorly defined. Human alveolar macrophages (AM) were exposed to SRM 1649 (Washington, DC, urban dust; UD), SRM 2975 (forklift diesel exhaust particles; DEP), and fine or coarse ambient PM collected in Chapel Hill, NC, during the late fall (November) and early summer (June) of 2001-2002. AM were subsequently incubated with lipopolysaccharide (LPS), phorbol myristate acetate (PMA), or calcium ionophore A23817 for 6 or 24 h after PM exposure. UD and DEP markedly suppressed O2- release 24 h post-PM exposure. UD exposure significantly inhibited tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-8 release after exposure to 10 nanog/ml LPS. DEP significantly suppressed only TNF-alpha and IL-6 release. Suppressed cytokine release may also be produced by reduced cellular cytokine production. Data suggested that decreased cytokine release is not produced by the presence of benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon. Comparison of TNF-alpha release after LPS, PMA, or A23817 revealed that suppressive effects of UD are LPS dependent, whereas inhibitory effects of DEP may work across multiple mechanistic pathways. November and June Chapel Hill PM exposure stimulated TNF-alpha and IL-8 release before LPS exposure. Fine and coarse November PM exposure markedly suppressed TNF-alpha release 6 h after LPS stimulation, but appeared to exert a stimulatory effect on IL-8 release 24 h after LPS exposure. June fine and coarse PM suppressed IL-8 release after LPS exposure. Data suggest that seasonal influences on PM composition affect AM inflammatory response before and after bacterial exposure. Overall, delayed or inhibited AM immune responses to LPS after PM exposure suggest human exposure to ambient PM may enhance pulmonary susceptibility to respiratory infections.
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Affiliation(s)
- K Sawyer
- Department of Environmental Science and Engineering, School of Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
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204
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Kusumoto S, Fukase K, Shiba T. Key structures of bacterial peptidoglycan and lipopolysaccharide triggering the innate immune system of higher animals: chemical synthesis and functional studies. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2010; 86:322-37. [PMID: 20431259 PMCID: PMC3417798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Accepted: 03/03/2010] [Indexed: 03/22/2024]
Abstract
Chemistry-based investigation is reviewed which led to identification of the active entities responsible for the immunostimulating potencies of peptidoglycan and lipopolysaccharide. Though these glycoconjugates which ubiquitously occur in wide range of bacteria as the essential components of their cell envelopes have long been known to enhance the immunological responses of higher animals, neither the precise chemical structures required nor the mechanism of their action had been [corrected] elucidated until early 1970s. Chemical synthesis of partial structures of peptidoglycan proved N-acetylmuramyl-L-alanyl-D-isoglutamine to be the minimum structure responsible for the activity and led to later identification of its receptor protein Nod2 present in animal cells. Another active partial structure of peptidoglycan, gamma-D-glutamyl-meso-diaminopimelic acid, and its receptor Nod1 were also identified as well. With regard to lipopolysaccharide, its glycolipid part named lipid A was purified and the structure studied. Chemically synthesized lipid A according to the newly elucidated structure exhibited full activity described for lipopolysaccharide known as endotoxin. Synthetic homogeneous lipid A and its structural analogues and labeled derivatives enabled precise studies of their interaction with receptor proteins and the mechanism of their action. Chemical synthesis of homogeneous partial structures of peptidoglycan and lipopolysaccharide gave unequivocal evidences for the concept that definite small molecular parts of these complex macromolecular bacterial glycoconjugates are specifically recognized by their respective receptors and trigger our defense system now widely recognized as innate immunity.
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Affiliation(s)
- Shoichi Kusumoto
- Suntory Institute for Bioorganic Research, Wakayamadai 1-1-1, Shimamotocho, Osaka, Japan.
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205
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Meng J, Lien E, Golenbock DT. MD-2-mediated ionic interactions between lipid A and TLR4 are essential for receptor activation. J Biol Chem 2009; 285:8695-702. [PMID: 20018893 DOI: 10.1074/jbc.m109.075127] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Lipopolysaccharide (LPS) activates innate immune responses through TLR4.MD-2. LPS binds to the MD-2 hydrophobic pocket and bridges the dimerization of two TLR4.MD-2 complexes to activate intracellular signaling. However, exactly how lipid A, the endotoxic moiety of LPS, activates myeloid lineage cells remains unknown. Lipid IV(A), a tetra-acylated lipid A precursor, has been used widely as a model for lipid A activation. For unknown reasons, lipid IV(A) activates proinflammatory responses in rodent cells but inhibits the activity of LPS in human cells. Using stable TLR4-expressing cell lines and purified monomeric MD-2, as well as MD-2-deficient bone marrow-derived macrophages, we found that both mouse TLR4 and mouse MD-2 are required for lipid IV(A) activation. Computational studies suggested that unique ionic interactions exist between lipid IV(A) and TLR4 at the dimerization interface in the mouse complex only. The negatively charged 4'-phosphate on lipid IV(A) interacts with two positively charged residues on the opposing mouse, but not human, TLR4 (Lys(367) and Arg(434)) at the dimerization interface. When replaced with their negatively charged human counterparts Glu(369) and Gln(436), mouse TLR4 was no longer responsive to lipid IV(A). In contrast, human TLR4 gained lipid IV(A) responsiveness when ionic interactions were enabled by charge reversal at the dimerization interface, defining the basis of lipid IV(A) species specificity. Thus, using lipid IV(A) as a selective lipid A agonist, we successfully decoupled and coupled two sequential events required for intracellular signaling: receptor engagement and dimerization, underscoring the functional role of ionic interactions in receptor activation.
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Affiliation(s)
- Jianmin Meng
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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206
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Mucosal vaccines: recent progress in understanding the natural barriers. Pharm Res 2009; 27:211-23. [PMID: 19953309 DOI: 10.1007/s11095-009-0011-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Accepted: 11/12/2009] [Indexed: 10/24/2022]
Abstract
It has long been known that protection against pathogens invading the organism via mucosal surfaces correlates better with the presence of specific antibodies in local secretions than with serum antibodies. The most effective way to induce mucosal immunity is to administer antigens directly to the mucosal surface. The development of vaccines for mucosal application requires antigen delivery systems and immunopotentiators that efficiently facilitate the presentation of the antigen to the mucosal immune system. This review provides an overview of the events within mucosal tissues that lead to protective mucosal immune responses. The understanding of those biological mechanisms, together with knowledge of the technology of vaccines and adjuvants, provides guidance on important technical aspects of mucosal vaccine design. Not being exhaustive, this review also provides information related to modern adjuvants, including polymeric delivery systems and immunopotentiators.
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207
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Gram-negative bacterial sensors for eukaryotic signal molecules. SENSORS 2009; 9:6967-90. [PMID: 22399982 PMCID: PMC3290508 DOI: 10.3390/s90906967] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 08/24/2009] [Accepted: 08/25/2009] [Indexed: 11/16/2022]
Abstract
Ample evidence exists showing that eukaryotic signal molecules synthesized and released by the host can activate the virulence of opportunistic pathogens. The sensitivity of prokaryotes to host signal molecules requires the presence of bacterial sensors. These prokaryotic sensors, or receptors, have a double function: stereospecific recognition in a complex environment and transduction of the message in order to initiate bacterial physiological modifications. As messengers are generally unable to freely cross the bacterial membrane, they require either the presence of sensors anchored in the membrane or transporters allowing direct recognition inside the bacterial cytoplasm. Since the discovery of quorum sensing, it was established that the production of virulence factors by bacteria is tightly growth-phase regulated. It is now obvious that expression of bacterial virulence is also controlled by detection of the eukaryotic messengers released in the micro-environment as endocrine or neuro-endocrine modulators. In the presence of host physiological stress many eukaryotic factors are released and detected by Gram-negative bacteria which in return rapidly adapt their physiology. For instance, Pseudomonas aeruginosa can bind elements of the host immune system such as interferon-γ and dynorphin and then through quorum sensing circuitry enhance its virulence. Escherichia coli sensitivity to the neurohormones of the catecholamines family appears relayed by a recently identified bacterial adrenergic receptor. In the present review, we will describe the mechanisms by which various eukaryotic signal molecules produced by host may activate Gram-negative bacteria virulence. Particular attention will be paid to Pseudomonas, a genus whose representative species, P. aeruginosa, is a common opportunistic pathogen. The discussion will be particularly focused on the pivotal role played by these new types of pathogen sensors from the sensing to the transduction mechanism involved in virulence factors regulation. Finally, we will discuss the consequence of the impact of host signal molecules on commensally or opportunistic pathogens associated with different human tissue.
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208
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Vamadevan AS, Fukata M, Arnold ET, Thomas LS, Hsu D, Abreu MT. Regulation of Toll-like receptor 4-associated MD-2 in intestinal epithelial cells: a comprehensive analysis. Innate Immun 2009; 16:93-103. [PMID: 19710105 DOI: 10.1177/1753425909339231] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The intestinal epithelium maintains a state of controlled inflammation despite continuous contact with Gram-negative commensal bacteria and lipopolysaccharide (LPS) on its luminal surface. Recognition of LPS by the Toll-like receptor (TLR) 4/MD-2 complex results in pro-inflammatory gene expression and cytokine secretion in intestinal epithelial cells (IECs). We have shown that IECs express low levels of MD-2 and TLR4 and are poorly responsive to LPS. In this study, we did a comprehensive analysis to understand the immune-mediated and epigenetic mechanisms by which IECs down-regulate MD-2 expression. Expression of MD-2 and TLR4 mRNA was examined in human inflammatory bowel disease and intestinal epithelial cell lines (T84, HT-29, Caco-2). Nuclear factor-kappaB transcriptional activation was used as a measure of LPS responsiveness. Intestinal epithelial cells in patients with inflammatory bowel disease exhibited increased expression of MD-2 and TLR4 mRNA. Lipopolysaccharide responsiveness in IECs was polarized to the basolateral membrane. Bisulfite sequencing of the MD-2 promoter demonstrated methylation of CpG dinucleotides. Inhibition of methylation by 5-azacytidine and histone de-actylation by trichostatin A, two forms of epigenetic silencing, resulted in increased mRNA expression of MD-2 in IECs. These results demonstrate various molecular mechanisms by which IECs down-regulate MD-2 and, thereby, protect against dysregulated inflammation to commensal bacteria in the intestinal lumen.
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Affiliation(s)
- Arunan S Vamadevan
- Division of Gastroenterology, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida 33101, USA
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209
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Argraves WS, Tanaka A, Smith EP, Twal WO, Argraves KM, Fan D, Haudenschild CC. Fibulin-1 and fibrinogen in human atherosclerotic lesions. Histochem Cell Biol 2009; 132:559-65. [PMID: 19693531 DOI: 10.1007/s00418-009-0628-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2009] [Indexed: 01/03/2023]
Abstract
Fibulin-1 is a fibrinogen-binding blood protein and a component of many extracellular matrices (ECM) including those of blood vessels. In this study, the deposition patterns of fibulin-1 and fibrinogen were examined in human coronary artery atherosclerotic lesions excised by atherectomy from 20 patients. Fibulin-1 deposition was found to be closely overlapping with fibrinogen located within the atherosclerotic lesions and in regions containing fresh thrombi. Pronounced intracellular fibulin-1 immunostaining was apparent in lesion areas rich in macrophages and foam cells, although THP-1 macrophages and foam cells were found not to express fibulin-1. Strong ECM deposition of fibulin-1 was observed in acellular atheromatous and myxomatous regions. By contrast, fibulin-1 was present at relatively low levels in the ECM associated with smooth muscle cells within and outside of lesions and was not detected in sclerotic regions. These results reveal the pattern of fibulin-1 within human atherosclerotic lesions and highlight the potential for fibulin-1, perhaps derived from the blood and acting in conjunction with fibrinogen, to play a role in the etiology and cardiovascular disease progression, particularly with respect to thrombotic aspects of atherosclerosis.
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Affiliation(s)
- W Scott Argraves
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425-2204, USA.
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210
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Alhawi M, Stewart J, Erridge C, Patrick S, Poxton IR. Bacteroides fragilis signals through Toll-like receptor (TLR) 2 and not through TLR4. J Med Microbiol 2009; 58:1015-1022. [PMID: 19528164 DOI: 10.1099/jmm.0.009936-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although it is desirable to identify the interactions between endotoxin/LPS and the innate immune mechanism, it is often not possible to isolate these interactions from other cell wall-related structures of protein or polysaccharide origin. There is no universally accepted method to extract different LPSs from different bacteria, and their natural state will be influenced by their interactions with the associated molecules in the bacterial outer membrane. It is now believed that Toll-like receptor (TLR) 4 is the main signal transducer of classical LPS (i.e. Escherichia coli LPS), while TLR2 is used by certain non-classical LPSs. There are contradictory reports as to whether Bacteroides fragilis LPS, a non-classical LPS, signals primarily through TLR2 or TLR4. This study was designed to address this problem. Different non-purified and purified B. fragilis LPSs extracted by different methods together with different heat-killed, whole-cell populations of B. fragilis were used to elucidate the TLR specificity. All of these B. fragilis preparations showed a significant signalling specificity for TLR2 but not for TLR4. This indicates that changing the extraction methods, with or without applying a repurification procedure, and varying the cell populations do not alter the TLR specificity of B. fragilis LPS.
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Affiliation(s)
- Mohammad Alhawi
- Medical Microbiology, Centre for Infectious Diseases, University of Edinburgh College of Medicine and Veterinary Medicine, Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - John Stewart
- Medical Microbiology, Centre for Infectious Diseases, University of Edinburgh College of Medicine and Veterinary Medicine, Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Clett Erridge
- Department of Cardiovascular Sciences, University of Leicester, Clinical Science Wing, Glenfield General Hospital, Leicester LE3 9QP, UK
| | - Sheila Patrick
- Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Ian R Poxton
- Medical Microbiology, Centre for Infectious Diseases, University of Edinburgh College of Medicine and Veterinary Medicine, Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
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211
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Nguyen TB, Kumar EVKS, Sil D, Wood SJ, Miller KA, Warshakoon HJ, Datta A, David SA. Controlling plasma protein binding: structural correlates of interactions of hydrophobic polyamine endotoxin sequestrants with human serum albumin. Mol Pharm 2009; 5:1131-7. [PMID: 19434925 DOI: 10.1021/mp8001123] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hydrophobically substituted polyamine compounds, particularly N-acyl or N-alkyl derivatives of homospermine, are potent endotoxin (lipopolysaccharide) sequestrants. Despite their polycationic nature, the aqueous solubilites are limited owing to the considerable overall hydrophobicity contributed by the long-chain aliphatic substituent, but solubilization is readily achieved in the presence of human serum albumin (HSA). We desired first to delineate the structural basis of lipopolyamine-albumin interactions and, second, to explore possible structure-activity correlates in a well-defined, congeneric series of N-alkyl and -acyl homospermine lead compounds. Fluorescence spectroscopic and isothermal titration calorimetry (ITC) results indicate that these compounds appear to bind to HSA via occupancy of the fatty-acid binding sites on the protein. The acyl and carbamate compounds bind HSA the strongest; the ureido and N-alkyl analogues are significantly weaker, and the branched alkyl compound is weaker still. ITC-derived dissociation constants are weighted almost in their entirety by enthalpic deltaH terms, which is suggestive that the polarizability of the carbonyl groups facilitate, at least in large part, their interactions with HSA. The relative affinities of these lipopolyamines toward HSA is reflected in discernible differences in apparent potencies of LPS-sequestering activity under experimental conditions requiring physiological concentrations of HSA, and also of in vivo pharmacodynamic behavior. These results are likely to be useful in designing analogues with varying pharmacokinetic profiles.
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Affiliation(s)
- Thuan B Nguyen
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, USA
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212
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Song JJ, Cho JG, Woo JS, Lee HM, Hwang SJ, Chae SW. Differential expression of toll-like receptors 2 and 4 in rat middle ear. Int J Pediatr Otorhinolaryngol 2009; 73:821-4. [PMID: 19303147 DOI: 10.1016/j.ijporl.2009.02.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 02/13/2009] [Accepted: 02/18/2009] [Indexed: 10/21/2022]
Abstract
OBJECTIVE The epithelial cells of the middle ear and Eustachian tube must maintain an adequate mucosal defense system against various antigenic stimuli. Since toll-like receptors (TLRs) are known to play a critical role in mucosal defense, we investigated their expression in the mucosa of the tubotympanum, nasopharynx, and oral cavity of the rat. METHOD The expression of TLR2 and TLR4 was examined in the mucosa of the tubotympanum, nasopharynx and oral cavity of the rat using real time RT-PCR and Western blot analysis. RESULTS Transcripts for TLR2 and TLR4 were detected in the mucosa of the tubotympanum, nasopharynx, and oral cavity of the rat. The expression of TLR2 and TLR4 in the middle ear was increased more than in the other anatomical areas. Differential expression of these molecules at the protein level was confirmed by Western blot analysis. CONCLUSIONS Diverse expression of TLR2 and TLR4 in different parts of the tubotympanum and upper aerodigestive tract suggests region-specific functional modulation of the innate immune system. Differential expression of subtypes of the TLR in the normal physiology of the tubotympanum and upper aerodigestive tract also suggests that they may play a role in the pathophysiology of otitis media.
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Affiliation(s)
- Jae-Jun Song
- Department of Otorhinolaryngology-Head and Neck Surgery, Dongguk University International Hospital, Gyeonggi, South Korea
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213
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Shi Z, Cai Z, Wen S, Chen C, Gendron C, Sanchez A, Patterson K, Fu S, Yang J, Wildman D, Finnell RH, Zhang D. Transcriptional regulation of the novel Toll-like receptor Tlr13. J Biol Chem 2009; 284:20540-7. [PMID: 19487701 DOI: 10.1074/jbc.m109.022541] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Little has been known about Tlr13 (Toll-like receptor 13), a novel member of the Toll-like receptor family. To elucidate the molecular basis of murine Tlr13 gene expression, the activity of the Tlr13 gene promoter was characterized. Reporter gene analysis and electrophoretic mobility shift assays demonstrated that Tlr13 gene transcription was regulated through three cis-acting elements that interacted with the Ets2, Sp1, and PU.1 transcription factors. Furthermore, our work suggests that these transcription factors may cooperate, culminating in maximal transcription of the Tlr13 gene. In contrast, NF-kappaB appeared to act as an inhibitor of Tlr13 transcription. Overexpression of Ets2 caused a strong increase in the transcriptional activity of the Tlr13 promoter; however, overexpression of NF-kappaB p65 dramatically inhibited it. Additionally, interferon-beta is capable of acting Tlr13 transcription, but the activated signaling of lipopolysaccharide/TLR4 and peptidoglycan/TLR2 strongly inhibited the Tlr13 gene promoter. Thus, these findings reveal the mechanism of Tlr13 gene regulation, thereby providing insight into the function of Tlr13 in the immune response to pathogen.
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Affiliation(s)
- Zhongcheng Shi
- Center for Infectious and Inflammatory Disease, Institute of Bioscience and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
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214
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Gonzalez JM, Ofori E, Burd I, Chai J, Scholler N, Elovitz MA. Maternal mortality from systemic illness: unraveling the contribution of the immune response. Am J Obstet Gynecol 2009; 200:430.e1-8. [PMID: 19318152 DOI: 10.1016/j.ajog.2009.01.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 12/24/2008] [Accepted: 01/23/2009] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Maternal morbidity and/or mortality (MM) is increased in pyelonephritis and influenza. Alterations in the immune response could account for the increase MM. We sought to determine whether the immune response is functionally different during pregnant and nonpregnant (NP) states. STUDY DESIGN Mouse model of systemic and localized inflammation was used. Maternal serum was assessed for expression of T-helper cell type 1 and 2 cytokines. Maternal spleens were harvested for immunohistochemistry. RESULTS Systemic administration of lipopolysaccharides resulted in no mortality to NP mice compared with 88% in preterm and 100% in term mice. A potent cytokine response was present in both NP and pregnancy. Systemic inflammation in pregnancy results in increased CD8 and CD11c expression in spleens. CONCLUSION Differences in cytokine response to systemic inflammation is unlikley to modulate the increased MM during pregnancy. Altered T-cell and dendritic cell responses in pregnancy may be responsible for the increase in MM.
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215
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Angiotensin II upregulates Toll-like receptor 4 and enhances lipopolysaccharide-induced CD40 expression in rat peritoneal mesothelial cells. Inflamm Res 2009; 58:473-82. [PMID: 19271152 DOI: 10.1007/s00011-009-0012-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2008] [Revised: 12/23/2008] [Accepted: 01/11/2009] [Indexed: 10/21/2022] Open
Abstract
OBJECTIVE Activation of Toll-like receptor 4 (TLR4) in peritoneal mesothelial cells by endotoxin contributes to peritoneal inflammation and fibrosis. Here we investigated TLR4 expression induced by angiotensin II (Ang II) and functional consequences of nuclear factor-kappaB (NF-kappaB) activation and CD40 expression in rat peritoneal mesothelial cells (RPMCs). METHODS TLR4, CD40, tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) were determined by reverse transcription polymerase chain reaction (RT-PCR) and TLR4, IkappaBalpha, phospho-IkappaBalpha, NF-kappaB p65, and phospho-NF-kappaB p65 were analyzed by Western blot. The intracellular distribution of NF-kappaB p65 was detected by immunofluorescence. RESULTS Treatment of RPMCs with Ang II resulted in an increase in the expression of TLR4 mRNA and protein levels. Preincubation of RPMCs with Ang II significantly increased lipopolysaccharide (LPS)-induced phospho-IkappaBalpha and phospho-NF-kappaB p65 protein (P < 0.05 vs. LPS alone) and CD40, TNF-alpha, and IL-6 mRNA levels (P < 0.05 vs. LPS alone). A significantly increased nuclear staining of NF-kappaB p65 in cells treated with Ang II plus LPS was also observed. CONCLUSIONS Ang II upregulates the expression of TLR4 by RPMCs, resulting in enhanced NF-kappaB signaling and induction of CD40, TNF-alpha, and IL-6 expression. Locally produced Ang II in the peritoneum may have an amplified role in LPS-induced peritoneal inflammation.
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216
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Pocivavsek A, Burns MP, Rebeck GW. Low-density lipoprotein receptors regulate microglial inflammation through c-Jun N-terminal kinase. Glia 2009; 57:444-53. [PMID: 18803301 PMCID: PMC2628955 DOI: 10.1002/glia.20772] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Apolipoprotein E (apoE) has been implicated in modulating the central nervous system (CNS) inflammatory response. However, the molecular mechanisms involved in apoE-dependent immunomodulation are poorly understood. We hypothesize that apoE alters the CNS inflammatory response by signaling via low-density lipoprotein (LDL) receptors in glia. To address this hypothesis, we used a small bioactive peptide formed from the receptor-binding domain of apoE, apoE peptide (EP), to study LDL receptor signaling in microglia. To model glial activation, we treated primary mouse microglia and the microglial cell line BV2 with lipopolysaccharide (LPS) and studied two inflammatory responses: an increase in nitric oxide production (NO) and a decrease in apoE production. We found that treatment of primary microglia and BV2 cells with EP attenuated LPS-induced NO accumulation and apoE reduction in a dose-dependent manner. Using the receptor-associated protein to block ligand binding to members of the LDL receptor family, we found that EP attenuated both of these LPS-induced inflammatory responses via LDL receptors. We studied two intracellular signaling cascades associated with apoE: c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK). LPS induced both ERK and JNK activation, whereas EP induced ERK activation, but drastically reduced JNK activation. Inhibition of JNK with SP600125 reduced LPS-induced NO production and apoE reduction in a dose-dependent manner. Treatment of microglia with suboptimal EP in combination with JNK inhibitor enhanced attenuation of LPS-induced NO production. These data suggest that microglial LDL receptors regulate JNK activation, which is necessary for apoE modulation of the inflammatory response.
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Affiliation(s)
- Ana Pocivavsek
- Department of Neuroscience, Georgetown University, New Research Building, Washington, District of Columbia 20057-1464, USA
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217
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Werling D, Jann OC, Offord V, Glass EJ, Coffey TJ. Variation matters: TLR structure and species-specific pathogen recognition. Trends Immunol 2009; 30:124-30. [PMID: 19211304 DOI: 10.1016/j.it.2008.12.001] [Citation(s) in RCA: 196] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 12/18/2008] [Accepted: 12/18/2008] [Indexed: 02/06/2023]
Abstract
Toll-like receptors (TLRs) are a family of pattern recognition receptors that are an important link between innate and adaptive immunity. Many vaccines incorporate ligands for TLRs as an adjuvant and are developed in rodent models, with the resulting data transferred to other species. Vaccine features can be improved markedly by emphasizing the biological relevance when evaluating other animal models for host-pathogen interaction and by taking greater advantage of the unique experimental opportunities that are offered by large animal, non-rodent models. Here, we aim to summarize our current knowledge of species-specific TLR responses and briefly discuss that vaccine efficacy in relevant host species might be improved by considering the species-specific TLR responses.
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Affiliation(s)
- Dirk Werling
- Royal Veterinary College. Department of Pathology and Infectious Diseases, Hawkshead Lane, Hatfield, AL9 7TA, UK.
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218
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Du T, Zhou ZG, You S, Huang G, Lin J, Yang L, Li X, Zhou WD, Chao C. Modulation of monocyte hyperresponsiveness to TLR ligands by 1,25-dihydroxy-vitamin D3 from LADA and T2DM. Diabetes Res Clin Pract 2009; 83:208-14. [PMID: 19010563 DOI: 10.1016/j.diabres.2008.09.046] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 09/21/2008] [Accepted: 09/29/2008] [Indexed: 11/28/2022]
Abstract
To investigate the differences of Toll-like receptors (TLRs) expression and response of monocyte and modulation of 1,25-dihydroxy-vitamin D3 on monocyte activity. Peripheral blood monocytes were collected from 23 healthy controls, 18 latent autoimmune diabetes in adults (LADA), and 22 type 2 diabetes mellitus (T2DM), respectively. CD14, TLR2 and TLR4 expression were analyzed. Moreover, the effect of 1,25-dihydroxy-vitamin D3 (1,25(OH)(2)D3) on monocyte response to lipoteichoic acid (LTA) and lipopolysaccharide (LPS) was evaluated in vitro by measuring phosphorylation level of NF-kappaB-p65 and associated cytokine production. Monocytes showed significantly higher surface CD14 expression from LADA compared with that from T2DM and controls, and high expression of TLR4 from LADA and T2DM than controls. After incubation with LPS or LTA, decreased surface expressions of CD14 were observed on monocytes from T2DM and controls, in contrast to the increased on monocytes from LADA. Activation of NF-kappaB and amounts of IL-1beta and TNF-alpha production by stimulation with ligands significantly increased in LADA and T2DM, which was modulated by 1,25(OH)(2)D3 to similar level, as compared to controls. The modulation of 1,25(OH)(2)D3 on monocytes makes us to consider more potency of vitamin D3 as therapy in LADA and T2DM.
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Affiliation(s)
- Tao Du
- Diabetes Center, Institute of Metabolism and Endocrinology, Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
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219
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Joo M, Kwon M, Cho YJ, Hu N, Pedchenko TV, Sadikot RT, Blackwell TS, Christman JW. Lipopolysaccharide-dependent interaction between PU.1 and c-Jun determines production of lipocalin-type prostaglandin D synthase and prostaglandin D2 in macrophages. Am J Physiol Lung Cell Mol Physiol 2009; 296:L771-9. [PMID: 19181746 DOI: 10.1152/ajplung.90320.2008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Previously, we reported that expression of lipocalin-prostaglandin D synthase (L-PGDS) is inducible in macrophages and protects from Pseudomonas pneumonia. Here, we investigated the mechanism by which L-PGDS gene expression is induced in macrophages. A promoter analysis of the murine L-PGDS promoter located a binding site of PU.1, a transcription factor essential for macrophage development and inflammatory gene expression. A chromatin immunoprecipitation assay showed that PU.1 bound to the cognate site in the endogenous L-PGDS promoter in response to LPS. Overexpression of PU.1, but not of PU.1(S148A), a mutant inert to casein kinase II (CKII) or NF-kappaB-inducing kinase (NIK), induced L-PGDS in RAW 264.7 cells. Conversely, siRNA silencing of PU.1 expression blunted productions of L-PGDS and prostaglandin D2 (PGD(2)). LPS treatment induced formation of the complex of PU.1 and cJun on the PU.1 site, but inactivation of cJun by treatment with JNK or p38 kinase inhibitor abolished the complex, and suppressed PU.1 transcriptional activity for L-PGDS gene expression. Together, these results show that PU.1, activated by CKII or NIK, cooperates with MAPK-activated cJun to maximally induce L-PGDS expression in macrophages following LPS treatment, and suggest that PU.1 participates in innate immunity through the production of L-PGDS and PGD(2).
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Affiliation(s)
- Myungsoo Joo
- School of Oriental Medicine, Pusan National University, Busan, Korea.
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220
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Wolfe DN, Buboltz AM, Harvill ET. Inefficient Toll-like receptor-4 stimulation enables Bordetella parapertussis to avoid host immunity. PLoS One 2009; 4:e4280. [PMID: 19169359 PMCID: PMC2627931 DOI: 10.1371/journal.pone.0004280] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Accepted: 11/24/2008] [Indexed: 01/09/2023] Open
Abstract
The recognition of bacterial lipopolysaccharide (LPS) by host Toll-like receptor (TLR)4 is a crucial step in developing protective immunity against several gram negative bacterial pathogens. Bordetella bronchiseptica and B. pertussis stimulate robust TLR4 responses that are required to control the infection, but a close relative, B. parapertussis, poorly stimulates this receptor, and TLR4 deficiency does not affect its course of infection. This led us to hypothesize that inefficient TLR4 stimulation enables B. parapertussis to evade host immunity. In a mouse model of infection, B. parapertussis grew rapidly in the lungs, but no measurable increase in TLR4-mediated cytokine, chemokine, or leukocyte responses were observed over the first few days of infection. Delivery of a TLR4 stimulant in the inoculum resulted in a robust inflammatory response and a 10- to 100-fold reduction of B. parapertussis numbers. As we have previously shown, B. parapertussis grows efficiently during the first week of infection even in animals passively immunized with antibodies. We show that this evasion of antibody-mediated clearance is dependent on the lack of TLR4 stimulation by B. parapertussis as co-inoculation with a TLR4 agonist resulted in 10,000-fold lower B. parapertussis numbers on day 3 in antibody-treated wild type, but not TLR4-deficient, mice. Together, these results indicate that inefficient TLR4 stimulation by B. parapertussis enables it to avoid host immunity and grow to high numbers in the respiratory tract of naïve and immunized hosts.
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Affiliation(s)
- Daniel N. Wolfe
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Anne M. Buboltz
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Graduate Program in Biochemistry, Microbiology, and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Eric T. Harvill
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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Du T, Zhou ZG, You S, Lin J, Yang L, Zhou WD, Huang G, Chao C. Regulation by 1, 25-dihydroxy-vitamin D3 on altered TLRs expression and response to ligands of monocyte from autoimmune diabetes. Clin Chim Acta 2009; 402:133-8. [PMID: 19210958 DOI: 10.1016/j.cca.2008.12.038] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 12/15/2008] [Accepted: 12/23/2008] [Indexed: 11/29/2022]
Abstract
BACKGROUND Altered Toll-like receptors (TLRs) expression and response of monocyte may be associated with insulin sensitivity, obesity and diabetes. METHODS Peripheral blood monocytes were respectively collected from 23 healthy controls, 16 type 1 diabetes mellitus (T1DM), and 18 latent autoimmune diabetes in adults (LADA). CD14, TLR2 and TLR4 expression were analyzed by flow cytometer. Moreover, the effect of 1, 25-dihydroxy-vitamin D3 (1,25(OH)(2)D3) on monocyte response to lipoteichoic acid (LTA) and lipopolysaccharide (LPS) was evaluated in vitro by measuring phosphorylation concentration of NF-kappaB-p65 and associated cytokine production. RESULTS Monocytes showed significantly higher surface CD14 and TLR4 expressions from LADA and lower CD14 expression from T1DM than controls. TLRs ligands decreased monocyte CD14 expression in T1DM but increased in LADA. Monocyte hyperresponsiveness to ligands was modulated by 1,25(OH)(2)D3 to similar concentration, as compared to controls. CONCLUSIONS Monocytes from T1DM and LADA showed similar cellular reactivity towards ligands and 1,25(OH)2D3 was observed to restore this defect to a certain extent in vitro.
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Affiliation(s)
- Tao Du
- Diabetes Center, Institute of Metabolism and Endocrinology, Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
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222
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Rockwell CE, Morrison DC, Qureshi N. Lipid A-mediated tolerance and cancer therapy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 667:81-99. [PMID: 20665202 DOI: 10.1007/978-1-4419-1603-7_8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The term "tolerance" from an immunological perspective, broadly encompasses a number of phenomena, but generally refers to a diminished responsiveness to LPS and/or other microbial products. With the discovery that many of the immunological, physiological and/or pathophysiological effects of LPS can be attributed to the lipid A moiety of the LPS molecule, a number of different lipid A analogs were synthesized with the goal of developing a drug that could be used clinically to treat cancer. In many instances, the development of tolerance to the lipid A congeners confounded the utility of these analogs as cancer therapeutics. In certain circumstances, however, the development of tolerance in patients has been utilized therapeutically to protect immunosuppressed patients from sepsis. Although numerous studies have been designed to investigate the development of tolerance, the underlying molecular mechanism remains unclear. This may be due, in part, to differences in the experimental models used, the sources and types of microbes and microbial products studied, kinetics of responses, and/or other experimental conditions. Nonetheless, a number of different signaling pathways have been identified as potentially modulating and/or triggering the development of tolerance. Though complex and incompletely understood, the capacity of tolerance to impact lipid A-based therapeutics, either positively or negatively, is inarguable, thus underscoring the necessity for further investigation toward elucidating the mechanisms contributing to the development of tolerance to lipid A and its analogs.
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Affiliation(s)
- Cheryl E Rockwell
- Department of Basic Medical Science, School of Medicine, Shock/Trauma Research Center, University of Missouri, 2411 Holmes Street, Kansas City, MO 64108, USA
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Abstract
Mammalian Toll-like receptors (TLRs) were first identified in 1997 based on their homology with Drosophila Toll, which mediates innate immunity in the fly. Over the past eight years, the number of manuscripts describing TLR expression and function in the central nervous system (CNS) has been increasing steadily and expanding beyond their traditional roles in infectious diseases to neurodegenerative disorders and injury. Interest in the field serves as the impetus for this volume in the Current Topics in Microbiology and Immunology series entitled Toll-Like Receptors: Roles in Infection and Neuropathology. The first five chapters highlight more traditional roles for TLRs in infectious diseases of the CNS. The second half of the volume discusses recently emerging roles for TLRs in noninfectious neurodegenerative diseases and the challenges faced by these models in identifying endogenous ligands. Several conceptual theories are introduced in various chapters that deal with the dual nature of TLR engagement and whether these signals favor neuroprotective versus neurodegenerative outcomes.
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225
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Han W, Joo M, Everhart MB, Christman JW, Yull FE, Blackwell TS. Myeloid cells control termination of lung inflammation through the NF-kappaB pathway. Am J Physiol Lung Cell Mol Physiol 2008; 296:L320-7. [PMID: 19098124 DOI: 10.1152/ajplung.90485.2008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Although acute lung inflammation in response to local or systemic infection involves myeloid and nonmyeloid cells, the interplay between different cell types remains poorly defined. Since NF-kappaB is a key transcription factor for innate immunity, we investigated whether dysregulated NF-kappaB activation in myeloid cells impacts inflammatory signaling in nonmyeloid cells and generation of neutrophilic lung inflammation in response to systemic endotoxemia. We generated bone marrow chimeras by fetal liver transplantation of cells deficient in IkappaBalpha or p50 into lethally irradiated NF-kappaB reporter transgenic mice. No differences were apparent between bone marrow chimeras in the absence of an inflammatory stimulus; however, following intraperitoneal injection of Escherichia coli lipopolysaccharide (LPS), IkappaBalpha- or p50-deficient bone marrow chimeras showed increased NF-kappaB activation in nonhematopoietic cells, exaggerated neutrophilic inflammation, and higher mortality compared with untransplanted reporter mice and wild-type bone marrow chimeras. Primary bone marrow-derived macrophages (BMDM) from IkappaBalpha(-/-) or p50(-/-) exhibited increased NF-kappaB activation and macrophage inflammatory protein-2 production after LPS treatment compared with wild-type cells, and coculture of BMDM with lung epithelial (A549) cells resulted in increased NF-kappaB activation in A549 cells and excess IL-8 production by these epithelial cells. These studies indicate an important role for inhibitory members of the NF-kappaB family acting specifically within myeloid cells to limit inflammatory responses in the lungs.
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Affiliation(s)
- Wei Han
- Department of Medicine, Division of Allergy, Pulmonary, Vanderbilt University School of Medicine, Nashville, Tennessee USA.
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226
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Innate microbial sensors and their relevance to allergy. J Allergy Clin Immunol 2008; 122:846-58; quiz 858-60. [PMID: 19000576 DOI: 10.1016/j.jaci.2008.10.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 10/02/2008] [Accepted: 10/02/2008] [Indexed: 01/01/2023]
Abstract
The innate immune system oversees the gateway to immunity with its microbial sensors. Innate microbial sensors are germ line-encoded receptors with genetically predetermined specificities for microbes. The readiness and effectiveness of the innate immune system to provide immediate and appropriate responses at the host-environment interface is dependent on its sensitive and comprehensive microbial detection systems. The purpose of this review is to provide an overview of innate microbial sensors, our growing understanding of their diverse repertoire, and their elegant structural and functional approaches to microbial recognition. Their relevance to allergic disease is also discussed: the potential recognition and uptake of allergens by some of these receptors, inhibited expression of other microbial sensors by allergic immune responses and inflammation, and their upregulation by microbial exposures in early life that may help to protect against the development of allergic immune responses and disease.
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227
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The brain expression of genes involved in inflammatory response, the ribosome, and learning and memory is altered by centrally injected lipopolysaccharide in mice. THE PHARMACOGENOMICS JOURNAL 2008; 9:116-26. [PMID: 18957951 DOI: 10.1038/tpj.2008.15] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Neuroinflammation plays a role in the progression of several neurodegenerative disorders. We used a lipopolysaccharide (LPS) model of neuroinflammation to characterize the gene expression changes underlying the inflammatory and behavioral effects of neuroinflammation. A single intracerebroventricular injection of LPS (5 microg) was administered into the lateral ventricle of mice and, 24 h later, we examined gene expression in the cerebral cortex and hippocampus using microarray technology. Gene Ontology (GO) terms for inflammation and the ribosome were significantly enriched by LPS, whereas GO terms associated with learning and memory had decreased expression. We detected 224 changed transcripts in the cerebral cortex and 170 in the hippocampus. Expression of Egr1 (also known as Zif268) and Arc, two genes associated with learning and memory, was significantly lower in the cortex, but not in the hippocampus, of LPS-treated animals. Overall, altered expression of these genes may underlie some of the inflammatory and behavioral effects of neuroinflammation.
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228
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Nakajima T, Ohtani H, Satta Y, Uno Y, Akari H, Ishida T, Kimura A. Natural selection in the TLR-related genes in the course of primate evolution. Immunogenetics 2008; 60:727-35. [DOI: 10.1007/s00251-008-0332-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Accepted: 09/04/2008] [Indexed: 10/21/2022]
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229
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Shashkin PN, Brown GT, Ghosh A, Marathe GK, McIntyre TM. Lipopolysaccharide is a direct agonist for platelet RNA splicing. THE JOURNAL OF IMMUNOLOGY 2008; 181:3495-502. [PMID: 18714022 DOI: 10.4049/jimmunol.181.5.3495] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Platelets express TLR4 receptors, but its ligand LPS does not directly activate thrombotic functions nor, obviously, transcription by these anucleate cells. Platelets, however, store information that changes their phenotype over a few hours in the form of unprocessed RNA transcripts. We show even low concentrations of LPS in the presence of soluble CD14 initiated splicing of unprocessed IL-1beta RNA, with translation and accumulation of IL-1beta protein. LPS was a more robust agonist for this response than thrombin. Platelets also contained cyclooxygenase-2 pre-mRNA, which also was spliced and translated after LPS stimulation. Flow cytometry and immunocytochemistry of platelets extensively purified by negative immunodepletion showed platelets contained IL-1beta, and quantitative assessment of white blood cell contamination by CD14 real time PCR confirms that leukocytes were not the IL-1beta source, nor were they required for platelet stimulation. LPS did not initiate rapid platelet responses, but over time did prime platelet aggregation to soluble agonists, induced actin rearrangement, and initiated granule secretion with P-selectin expression that resulted the coating of quiescent leukocytes with activated platelets. LPS is a direct agonist for platelets that allows these cells to directly participate in the innate immune response to bacteria.
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Affiliation(s)
- Pavel N Shashkin
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine, Cleveland, OH 44195, USA
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230
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Suzuki H, Suzuki Y, Narita I, Aizawa M, Kihara M, Yamanaka T, Kanou T, Tsukaguchi H, Novak J, Horikoshi S, Tomino Y. Toll-like receptor 9 affects severity of IgA nephropathy. J Am Soc Nephrol 2008; 19:2384-95. [PMID: 18776126 DOI: 10.1681/asn.2007121311] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Environmental pathogens are suspected to aggravate renal injury in IgA nephropathy (IgAN), but neither underlying mechanisms nor specific exogenous antigens have been identified. In this study, a genome-wide scan of ddY mice, which spontaneously develop IgAN, was performed, and myeloid differentiation factor 88 (MyD88) was identified as a candidate gene for progression of renal injury (chi(2) = 21.103, P = 0.00017). For evaluation of the potential influence of environmental pathogens on progression of renal injury, ddY mice were housed in either conventional or specific pathogen-free conditions. Expression of genes encoding toll-like receptors (TLR) and the signaling molecule MyD88 were quantified by real-time reverse transcription-PCR in splenocytes. Although the housing conditions did not affect the prevalence of IgAN, the severity of renal injuries was higher in the conventionally housed group. Mice that had IgAN and were housed in conventional conditions had higher levels of TLR9 and MyD88 transcripts than mice that had IgAN and were housed in specific pathogen-free conditions. Furthermore, nasal challenge with CpG-oligodeoxynucleotides, which are ligands for TLR9, aggravated renal injury, led to strong Th1 polarization, and increased serum and mesangial IgA. For investigation of whether these results may be generalizable to humans, single-nucleotide polymorphisms in the TLR9 and MyD88 genes were analyzed in two cohorts of patients with IgAN; an association was observed between TLR9 polymorphisms and disease progression. In summary, these findings suggest that activation of the TLR9/MyD88 pathway by common antigens may affect the severity of IgAN.
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Affiliation(s)
- Hitoshi Suzuki
- Division of Nephrology, Department of Internal Medicine, Juntendo University School of Medicine, Tokyo, Japan
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231
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Keestra AM, van Putten JPM. Unique Properties of the Chicken TLR4/MD-2 Complex: Selective Lipopolysaccharide Activation of the MyD88-Dependent Pathway. THE JOURNAL OF IMMUNOLOGY 2008; 181:4354-62. [DOI: 10.4049/jimmunol.181.6.4354] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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232
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Chassin C, Vimont S, Cluzeaud F, Bens M, Goujon JM, Fernandez B, Hertig A, Rondeau E, Arlet G, Hornef MW, Vandewalle A. TLR4 facilitates translocation of bacteria across renal collecting duct cells. J Am Soc Nephrol 2008; 19:2364-74. [PMID: 18753256 DOI: 10.1681/asn.2007121273] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Uropathogenic Escherichia coli (UPEC) are the most frequent causes of urinary tract infections and pyelonephritis. Renal medullary collecting duct (MCD) cells are the intrarenal site to which UPEC strains prefer to adhere and initiate an inflammatory response, but the ability of UPEC strains to translocate across impermeant MCD cells has not been demonstrated definitively. Here, several UPEC strains adhered to the apical surface and translocated across confluent murine inner MCD cells grown on filters. UPEC strains expressing cytolytic and vacuolating cytotoxins disrupted the integrity of cell layers, whereas noncytolytic UPEC strains passed through the cell layers without altering tight junctions. Apical-to-basal transcellular translocation was dramatically reduced after extinction of Toll-like receptor 4 (TLR4) and the lipid raft marker caveolin-1 by small interfering RNA. Furthermore, disruption of lipid raft integrity by filipin III and methyl-beta-cyclodextrin significantly reduced both the transcellular translocation of UPEC across murine inner MCD cell layers and the stimulation of proinflammatory mediators. Bacterial translocation was also significantly reduced in primary cultures of TLR4-deficient mouse MCD cells compared with MCD cells from wild-type mice. Benzyl alcohol, an anesthetic that enhances membrane fluidity, favored the recruitment of caveolin-1 in lipid rafts and increased the translocation of UPEC across cultured TLR4-deficient MCD cells. These findings demonstrate that the transcellular translocation of UPEC strains across impermeant layers of MCD cells may occur through lipid rafts via a TLR4-facilitated process.
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Affiliation(s)
- Cécilia Chassin
- INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, BP 416, Paris, France
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233
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Lizundia R, Sauter KS, Taylor G, Werling D. Host species-specific usage of the TLR4-LPS receptor complex. Innate Immun 2008; 14:223-31. [PMID: 18669608 DOI: 10.1177/1753425908095957] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Recognition of LPS depends on the interaction of at least three molecules forming the LPS-receptor complex. The most important ones, CD14, MD2 and Toll-like receptor (TLR) 4 share a high degree of homology between species. In the present study, we investigated the importance of species-specific restriction on the recognition of LPS using stably transfected HEK293 cell lines expressing either human or bovine LPS-receptor complex components. Species-specific MD2 appeared to confer LPS recognition, whereas species-specific CD14 only appeared to play a minor role. In addition to the recognition of LPS, there is evidence that the fusion (F) protein of respiratory syncytial virus (RSV), which is the most common viral respiratory pathogen during infancy world-wide, interacts with TLR4, and plays an important role in the initiation of the innate immune response. Our findings suggest that human and bovine RSV may activate human and bovine TLR4 receptors, respectively, in the presence of both MD2 and CD14. However, no clear role for the RSV F protein of either human or bovine RSV alone in stimulating TLR4-dependent NF-kappaB activation was observed.
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234
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Hellmig S, Fischbach W, Goebeler-Kolve ME, Fölsch UR, Hampe J, Schreiber S. Association study of a functional Toll-like receptor 4 polymorphism with susceptibility to gastric mucosa-associated lymphoid tissue lymphoma. Leuk Lymphoma 2008; 46:869-72. [PMID: 16019531 DOI: 10.1080/1042819050086451] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Toll-like receptor 4, as part of innate immune response, is the main receptor for lipopolysaccharide on marginal zone B cells. The rare allele of TLR4 Asp299Gly attenuates receptor signaling and diminishes the inflammatory response. We genotyped 87 patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma, 594 Helicobacter pylori positive controls and 358 healthy blood donors to investigate an association of TLR4 Asp299Gly in the development of gastric MALT lymphoma. Heterozygote genotype was significantly less frequent in patients with gastric MALT lymphoma compared to H. pylori-infected controls (4.6% vs. 11.6%, Fischer's exact P=0.019, odds ratio=0.37, 95% confidence interval 0.13-1.03). Because 10% of caucasians are carriers of the rare allele G TLR4 Asp299Gly appears to be only one factor in the genetic susceptibility to gastric lymphoma. Further studies in larger samples are needed to confirm our findings and fully elucidate the role of TLR4 and its genetic variants in the pathophysiology of H. pylori infection and gastric lymphoma.
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Affiliation(s)
- Stephan Hellmig
- Klinik für Allgemeine Innere Medizin, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel, Germany.
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Farhat K, Sauter KS, Brcic M, Frey J, Ulmer AJ, Jungi TW. The response of HEK293 cells transfected with bovine TLR2 to established pathogen-associated molecular patterns and to bacteria causing mastitis in cattle. Vet Immunol Immunopathol 2008; 125:326-36. [PMID: 18621422 DOI: 10.1016/j.vetimm.2008.05.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 05/22/2008] [Accepted: 05/30/2008] [Indexed: 12/18/2022]
Abstract
Toll-like receptors (TLRs) are key sensors of pathogen-associated molecular patterns (PAMPs). Their role in immunity is difficult to examine in species of veterinary interest, due to restricted access to the knockout technology and TLR-specific antibodies. An alternative approach is to generate cell lines transfected with various TLRs and to examine the recognition of PAMPs or relevant bacteria. In this report, we examined whether recognition of various PAMPs and mastitis-causing bacteria is achieved by transfection of recombinant bovine TLR2 (boTLR2). Therefore, human embryonic kidney (HEK) 293 cells were transfected by whole boTLR2. A clonal analysis of stably transfected cells disclosed variable recognition of several putative TLR2 agonists although expressing similar amounts of the transgene and endogenous TLR6. One clone (clone 25) reacted by copious interleukin-8 (IL-8) production to several stimulants of TLR2 such as di-palmitoylated cysteyl-seryl-lysyl-lysyl-lysyl-lysine (Pam2), a biochemical preparation of lipoteichoic acid from Staphylococcus aureus, a commercial preparation of peptidoglycan from S. aureus, and heat-killed Listeria monocytogenes (HKLM). TLR2-dependent induction of IL-8 release was stronger in medium containing human serum albumin than in medium containing fetal calf serum. Clone 25 cells responded to high concentrations of S. aureus and to Escherichia coli causing mastitis, but not to Streptococcus uberis and to Streptococcus agalactiae which also cause mastitis. Stimulation by S. aureus was relatively weak when compared (i) with stimulation of the same cells by HKLM and PAMPs derived from S. aureus, (ii) with a clone stably transfected with TLR4 and MD-2 and stimulated by E. coli causing mastitis, and (iii) with interferon-gamma-costimulated bovine macrophages stimulated by S. aureus and S. agalactiae. Thus, clone 25 is suitable for studying the interaction of putative TLR2 agonists with bovine TLR2-transfected cells, provides a cell to search for TLR2-specific antibodies, and is a tool for studying the interaction of TLR2 with bacteria causing disease, e.g. mastitis, in cattle.
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Affiliation(s)
- Katja Farhat
- Department of Immunology and Cell Biology, Research Center Borstel, Borstel, Germany
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236
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Differential activation of human and mouse Toll-like receptor 4 by the adjuvant candidate LpxL1 of Neisseria meningitidis. Infect Immun 2008; 76:3801-7. [PMID: 18490457 DOI: 10.1128/iai.00005-08] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neisseria meningitidis LpxL1 lipopolysaccharide (LPS) bearing penta-acylated lipid A is considered a promising adjuvant candidate for inclusion in future N. meningitidis vaccines, as it elicits a markedly reduced endotoxic response in human macrophages relative to that in wild-type (hexa-acylated) LPS, while it is an equally effective adjuvant in mice. As dendritic cells (DC) and Toll-like receptors (TLR) are regarded as central mediators in the initiation of an immune response, here we evaluated the ability of LpxL1 LPS to mature and to activate human DC and examined its TLR4-/MD-2-activating properties. Unexpectedly, purified LpxL1 LPS displayed minimal human DC-stimulating properties compared to wild-type LPS. Although whole bacteria induced DC maturation and activation irrespective of their type of LPS, the LpxL1 mutant failed to activate the human recombinant TLR4/MD-2 complex expressed in HeLa cells. Similarly, purified LpxL1 LPS was unable to activate human TLR4/MD-2 and it even acted as an antagonist of wild-type LPS. Both wild-type and LpxL1 LPSs activated the murine TLR4/MD-2 complex, consistent with their abilities to induce maturation and activation of murine DC. Assays with cells transfected with different combinations of human and murine TLR4 and MD-2 indicated that TLR4 was a more-major determinant of the LPS response than MD-2. The species-specific activation of the TLR4/MD-2 complex by LpxL1 LPS may have an impact on the use of LpxL1 LPS as an adjuvant and the use of murine immunization models in human meningococcal vaccine development.
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237
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Sheu JJ, Chang LT, Chiang CH, Youssef AA, Wu CJ, Lee FY, Yip HK. Prognostic value of activated toll-like receptor-4 in monocytes following acute myocardial infarction. Int Heart J 2008; 49:1-11. [PMID: 18360060 DOI: 10.1536/ihj.49.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study tested the hypothesis that activated toll-like receptor-4 (TLR-4) is closely related to combined major adverse clinical outcomes (MACO) [defined as advanced Killip score (> or = 3), overt congestive heart failure (CHF) (New York Heart Association functional class > or = 2) or 30-day death] in patients with ST-segment elevation (ST-se) acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI). We conducted a prospective cohort study in 43 consecutive patients with ST-se AMI of onset < 12 hours who were undergoing primary PCI. Blood samples for TLR-4 and serum level of tumor necrosis factor-alpha (TNF-alpha) were collected from 43 patients at 24 hours after AMI and from 20 normal outpatients. The experimental results revealed significantly higher baseline levels of TLR-4, TNF-alpha and white blood cell (WBC) count in the study patients than in normal control subjects (all P < 0.0001). Additionally, baseline levels of TLR-4, TNF-alpha , creatinine, peak level of CK-MB, and multiple vessel disease were significantly higher, whereas left ventricular performance was notably lower in patients (n = 18) with occurrence of MACO than in patients (n = 25) without occurrence of MACO (all P < 0.05). Furthermore, the level of lipopolysaccharide (LPS)-stimulated LTR-4 was significantly increased in MACO patients than in those without MACO (P < 0.0001). Moreover, LPS-stimulated TLR-4 was the most independent predictor of 30-day MACO (P < 0.01). In patients with ST-se AMI, activated TLR-4 is independently predictive of 30-day MACO.
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Affiliation(s)
- Jiunn-Jye Sheu
- Department of Cardiovascular Surgery, Chang Gung Memorial Hospital, Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan, ROC
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238
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Schröder NW, Eckert J, Stübs G, Schumann RR. Immune responses induced by spirochetal outer membrane lipoproteins and glycolipids. Immunobiology 2008; 213:329-40. [DOI: 10.1016/j.imbio.2007.11.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 10/18/2007] [Accepted: 11/01/2007] [Indexed: 02/06/2023]
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239
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Kimbrell MR, Warshakoon H, Cromer JR, Malladi S, Hood JD, Balakrishna R, Scholdberg TA, David SA. Comparison of the immunostimulatory and proinflammatory activities of candidate Gram-positive endotoxins, lipoteichoic acid, peptidoglycan, and lipopeptides, in murine and human cells. Immunol Lett 2008; 118:132-41. [PMID: 18468694 DOI: 10.1016/j.imlet.2008.03.009] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2008] [Revised: 03/13/2008] [Accepted: 03/21/2008] [Indexed: 01/07/2023]
Abstract
The role of lipopolysaccharide (LPS) in the pathogenesis of Gram-negative septic shock is well established. The corresponding proinflammatory and immunostimulatory molecule(s) on the Gram-positive bacteria is less well understood, and its identification and characterization would be a key prerequisite in designing specific sequestrants of the Gram-positive endotoxin(s). We report in this paper the comparison of NF-kappaB-, cytokine- and chemokine-inducing activities of the TLR2 ligands, lipoteichoic acid (LTA), peptidoglycan (PGN), and lipopeptides, to LPS, a prototype TLR4 agonist, in murine macrophage cell-lines as well as in human blood. In murine cells, di- and triacyl liopopeptides are equipotent in their NF-kappaB inducing activity relative to LPS, but elicit much lower proinflammatory cytokines. However, both LPS and the lipopeptides potently induce the secretion of a pattern of chemokines that is suggestive of the engagement of a TLR4-independent TRIF pathway. In human blood, although the lipopeptides induce p38 MAP kinase phosphorylation and CD11b upregulation in granulocytes at ng/ml concentrations, they do not elicit proinflammatory cytokine production even at very high doses; LTA, however, activates neutrophils and induces cytokine secretion, although its potency is considerably lower than that of LPS, presumably due to its binding to plasma proteins. We conclude that, in human blood, the pattern of immunostimulation and proinflammatory mediator production elicited by LTA parallels that of LPS.
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240
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De Smedt-Peyrusse V, Sargueil F, Moranis A, Harizi H, Mongrand S, Layé S. Docosahexaenoic acid prevents lipopolysaccharide-induced cytokine production in microglial cells by inhibiting lipopolysaccharide receptor presentation but not its membrane subdomain localization. J Neurochem 2008; 105:296-307. [DOI: 10.1111/j.1471-4159.2007.05129.x] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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241
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Mouihate A, Harré EM, Martin S, Pittman QJ. Suppression of the febrile response in late gestation: evidence, mechanisms and outcomes. J Neuroendocrinol 2008; 20:508-14. [PMID: 18266941 PMCID: PMC3547979 DOI: 10.1111/j.1365-2826.2008.01666.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Fever is a beneficial host defence response. However, fever caused by the immune stimulant, lipopolysaccharide (LPS), are attenuated in many species during pregnancy, particularly near term. A number of parallel mechanisms may be responsible, and these vary in magnitude according to the time of gestation, type of inflammatory stimulus and species of animal. Some studies report a reduction in the plasma levels of circulating pro-inflammatory cytokines such as tumour necrosis factor-alpha, interleukin-1beta and interleukin-6 along with increased levels of anti-inflammatory cytokines such as interleukin-1 receptor antagonist. Associated with the attenuated febrile response to LPS is a reduction in the activation of the prostaglandin synthesising enzyme, cyclo-oxygenase 2, resulting in reduced levels of the obligatory prostaglandin mediators of the febrile response in the brain. There is also a reduction in the sensitivity of the brain to the pyrogenic action of prostaglandins, which does not appear to be due to a change in the levels of hypothalamic EP3 prostaglandin receptors. The suppression of fever at term may be important for the health of the neonate because fever in pregnant mothers may be harmful to the late-term foetus and neonate.
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Affiliation(s)
- A Mouihate
- Department of Physiology and Biophysics, Hotchkiss Brain Institute, Institutes of Infection, Immunity and Inflammation and Maternal and Child Health, University of Calgary, Calgary, Alberta, Canada
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242
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Wang L, Li D, Yang K, Hu Y, Zeng Q. Toll-like receptor-4 and mitogen-activated protein kinase signal system are involved in activation of dendritic cells in patients with acute coronary syndrome. Immunology 2008; 125:122-30. [PMID: 18373609 DOI: 10.1111/j.1365-2567.2008.02827.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Atherosclerosis is an inflammatory disease in which dendritic cells have been suggested to play an essential role. The underlying signalling mechanisms are unknown thus far. The family of Toll-like receptors (TLRs) initiates innate immune responses, and Toll-like receptor-4 (TLR4) has been considered to be an important player in the initiation and progression of atherosclerotic disease. The highly conserved mitogen-activated protein kinase (MAPK) family is one of the major kinase families that regulate cells by transducing extracellular into cellular responses. Three important members of this family are the extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK). The aim of the study was to investigate the expression of TLR4 and MAPK families on dendritic cells (DC) in patients with coronary arteriosclerosis disease. We have examined the expression of TLR4 protein and mRNA by flow cytometry and real-time quantitative reverse transcription polymerase chain reaction (RT-PCR). In addition, the expression of MAPK family proteins have been determined by Western blot analysis. We examined the expression level of CD80 to value the maturation state of DC. We compared the levels of cytokines in DC in response to lipopolysaccharide (LPS). The results showed that the expression of TLR4 and MAPK families are increased in the patients with acute coronary syndrome (ACS), compared with it in the patients with stable angina and controls. DC in ACS are activated evaluated by its mature marker and cytokine secreting responding to LPS. We suggest that TLR4 and MAPK families maybe involved in activation of circulating DC of ACS patients.
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Affiliation(s)
- Lei Wang
- Department of Cardiology, Institute of Cardiovascular Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
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243
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Drosomycin-like defensin, a human homologue of Drosophila melanogaster drosomycin with antifungal activity. Antimicrob Agents Chemother 2008; 52:1407-12. [PMID: 18212107 DOI: 10.1128/aac.00155-07] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Innate antifungal defense in Drosophila melanogaster relies on the activation of the Toll molecule and the release of drosomycin, a defensin-like molecule with antifungal properties. Ten human homologues of Toll have been described, with central roles in activation of the innate host defense. In the present study, we report a putative human homologue of the Drosophila-derived drosomycin, designated drosomycin-like defensin (DLD). Synthetic DLD displays a broad spectrum of activity against Aspergillus spp. and other clinically relevant filamentous fungi. These effects are specific for filamentous fungi; no activity has been found against yeasts or gram-positive or gram-negative bacteria. Synthetic DLD also displays immunomodulatory effects on Aspergillus-stimulated cytokine production. In addition, we show the expression of DLD mRNA in several human tissues, particularly in the skin, consistent with its putative role as a defensin against invading microorganisms. This is the first indication of an endogenous human peptide with specific antifungal activity, which is probably central in the defense against infections with molds.
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244
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Beutler B. Neo-ligands for innate immune receptors and the etiology of sterile inflammatory disease. Immunol Rev 2008; 220:113-28. [PMID: 17979843 DOI: 10.1111/j.1600-065x.2007.00577.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Microbe recognition based on a small collection of germline-encoded receptors carries a hidden liability: the possibility that mutational changes in the proteome will lead to self-recognition. The risk of self-recognition is enhanced, because innate immune receptors display low specificity, as they are driven to accommodate heterogeneous signature molecules found in the microbial world. The proteome structure is globally constrained by the innate immune sensing apparatus to satisfy a proscription against self-reactivity. But accidents happen, and here it is proposed that mutations creating neo-ligands for innate immune receptors are the proximal cause of sterile inflammatory diseases, which in turn embody the selective pressure that constrains the proteome. Such mutations are predictably dominant and may occur in the germline and also in somatic cells (e.g. in lymphocytes), causing inflammatory effects upon clonal expansion. They may also account for the inflammatory character of selected neoplastic diseases. The neo-ligand hypothesis accounts for the heritability, ambiguous linkage characteristics, phenotypic heterogeneity, and natural history of diverse forms of sterile inflammation. It explains sterile inflammatory diseases as conditions in which aberrant immune signaling is caused by proteome encroachment upon the ligand-recognition space over which the innate immune system stands guard.
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245
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Okemoto K, Hanada K, Nishijima M, Kawasaki K. The Preparation of a Lipidic Endotoxin Affects Its Biological Activities. Biol Pharm Bull 2008; 31:1952-4. [DOI: 10.1248/bpb.31.1952] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Kazuo Okemoto
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases
| | - Kentaro Hanada
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases
| | - Masahiro Nishijima
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases
- The National Institute of Health Sciences
| | - Kiyoshi Kawasaki
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases
- Faculty of Pharmaceutical Sciences, Doshisha Women's College
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246
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Choi SH, Langenbach R, Bosetti F. Genetic deletion or pharmacological inhibition of cyclooxygenase-1 attenuate lipopolysaccharide-induced inflammatory response and brain injury. FASEB J 2007; 22:1491-501. [PMID: 18162486 DOI: 10.1096/fj.07-9411com] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cyclooxygenase (COX) -1 and -2 metabolize arachidonic acid to prostanoids and reactive oxygen species, major players in the neuroinflammatory process. While most reports have focused on the inducible isoform, COX-2, the contribution of COX-1 to the inflammatory response is unclear. In the present study, the contribution of COX-1 in the neuroinflammatory response to intracerebroventricular lipopolysaccharide (LPS) was investigated using COX-1 deficient (COX-1(-/-)) mice or wild-type (COX-1(+/+)) mice pretreated with SC-560, a selective COX-1 inhibitor. Twenty-four hours after lipopolysaccharide (LPS) injection, COX-1(-/-) mice showed decreased protein oxidation and LPS-induced neuronal damage in the hippocampus compared with COX-1(+/+) mice. COX-1(-/-) mice showed a significant reduction of microglial activation, proinflammatory mediators, and expression of COX-2, inducible NOS, and NADPH oxidase. The transcriptional down-regulation of cytokines and other inflammatory markers in COX-1(-/-) mice was mediated by a reduced activation of NF-kappaB and signal transducer and activator of transcription 3. Administration of SC-560 prior to LPS injection also attenuated the neuroinflammatory response by decreasing brain levels of prostaglandin (PG)E(2), PGD(2), PGF(2alpha), and thromboxane B(2), as well as the expression of proinflammatory cytokines and chemokine. These findings suggest that COX-1 plays a previously unrecognized role in neuroinflammatory damage.
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Affiliation(s)
- Sang-Ho Choi
- Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA
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247
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Pei Z, Pang H, Qian L, Yang S, Wang T, Zhang W, Wu X, Dallas S, Wilson B, Reece JM, Miller DS, Hong JS, Block ML. MAC1 mediates LPS-induced production of superoxide by microglia: the role of pattern recognition receptors in dopaminergic neurotoxicity. Glia 2007; 55:1362-73. [PMID: 17654704 DOI: 10.1002/glia.20545] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Microglia-derived superoxide is critical for the inflammation-induced selective loss of dopaminergic (DA) neurons, but the underlying mechanisms of microglial activation remain poorly defined. Using neuron-glia and microglia-enriched cultures from mice deficient in the MAC1 receptor (MAC1-/-), we demonstrate that lipopolysaccharide (LPS) treatment results in lower TNFalpha response, attenuated loss of DA neurons, and absence of extracellular superoxide production in MAC1-/- cultures. Microglia accumulated fluorescently labeled LPS in punctate compartments associated with the plasma membrane, intracellular vesicles, and the Golgi apparatus. Cytochalasin D (CD), an inhibitor of phagocytosis, blocked LPS internalization. However, microglia derived from Toll-like receptor 4 deficient mice and MAC1-/- mice failed to show a significant decrease in intracellular accumulation of labeled LPS, when compared with controls. Pretreatment with the scavenger receptor inhibitor, fucoidan, inhibited 79% of LPS accumulation in microglia without affecting superoxide, indicating that LPS internalization and superoxide production are mediated by separate phagocytosis receptors. Together, these data demonstrate that MAC1 is essential for LPS-induced superoxide from microglia, implicating MAC1 as a critical trigger of microglial-derived oxidative stress during inflammation-mediated neurodegeneration.
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Affiliation(s)
- Zhong Pei
- Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
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248
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Kim HM, Park BS, Kim JI, Kim SE, Lee J, Oh SC, Enkhbayar P, Matsushima N, Lee H, Yoo OJ, Lee JO. Crystal structure of the TLR4-MD-2 complex with bound endotoxin antagonist Eritoran. Cell 2007; 130:906-17. [PMID: 17803912 DOI: 10.1016/j.cell.2007.08.002] [Citation(s) in RCA: 843] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 07/23/2007] [Accepted: 08/02/2007] [Indexed: 10/22/2022]
Abstract
TLR4 and MD-2 form a heterodimer that recognizes LPS (lipopolysaccharide) from Gram-negative bacteria. Eritoran is an analog of LPS that antagonizes its activity by binding to the TLR4-MD-2 complex. We determined the structure of the full-length ectodomain of the mouse TLR4 and MD-2 complex. We also produced a series of hybrids of human TLR4 and hagfish VLR and determined their structures with and without bound MD-2 and Eritoran. TLR4 is an atypical member of the LRR family and is composed of N-terminal, central, and C-terminal domains. The beta sheet of the central domain shows unusually small radii and large twist angles. MD-2 binds to the concave surface of the N-terminal and central domains. The interaction with Eritoran is mediated by a hydrophobic internal pocket in MD-2. Based on structural analysis and mutagenesis experiments on MD-2 and TLR4, we propose a model of TLR4-MD-2 dimerization induced by LPS.
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Affiliation(s)
- Ho Min Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejon, Korea 305-701
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249
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Joo M, Kwon M, Sadikot RT, Kingsley PJ, Marnett LJ, Blackwell TS, Peebles RS, Urade Y, Christman JW. Induction and function of lipocalin prostaglandin D synthase in host immunity. THE JOURNAL OF IMMUNOLOGY 2007; 179:2565-75. [PMID: 17675519 DOI: 10.4049/jimmunol.179.4.2565] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although mainly expressed in neuronal cells, lipocalin-type PGD synthase (L-PGDS) is detected in the macrophages infiltrated to atherosclerotic plaques. However, the regulation and significance of L-PGDS expression in macrophages are unknown. Here, we found that treatment of macrophages with bacterial endotoxin (LPS) or Pseudomonas induced L-PGDS expression. Epigenetic suppression of L-PGDS expression in macrophages blunted a majority of PGD(2) produced after LPS treatment. Chromatin immunoprecipitation assays show that L-PGDS induction was regulated positively by AP-1, but negatively by p53. L-PGDS expression was detected in whole lung and alveolar macrophages treated with LPS or Pseudomonas. L-PGDS overexpressing transgenic mice improved clearance of Pseudomonas from the lung compared with nontransgenic mice. Similarly, intratracheal instillation of PGD(2) enhanced removal of Pseudomonas from the lung in mice. In contrast, L-PGDS knockout mice were impaired in their ability to remove Pseudomonas from the lung. Together, our results identify induction of L-PGDS expression by inflammatory stimuli or bacterial infection, the regulatory mechanism of L-PGDS induction, and the protective role of L-PGDS expression in host immune response. Our study suggests a potential therapeutic usage of L-PGDS or PGD(2) against Pseudomonas pneumonia.
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MESH Headings
- Animals
- Atherosclerosis/genetics
- Atherosclerosis/immunology
- Atherosclerosis/pathology
- Cell Line
- Epigenesis, Genetic/drug effects
- Epigenesis, Genetic/genetics
- Epigenesis, Genetic/immunology
- Gene Expression Regulation, Enzymologic/drug effects
- Gene Expression Regulation, Enzymologic/genetics
- Gene Expression Regulation, Enzymologic/immunology
- Immunity, Innate/genetics
- Intramolecular Oxidoreductases/biosynthesis
- Intramolecular Oxidoreductases/deficiency
- Intramolecular Oxidoreductases/immunology
- Lipocalins
- Lipopolysaccharides/immunology
- Lipopolysaccharides/pharmacology
- Macrophages/enzymology
- Macrophages/immunology
- Macrophages/pathology
- Mice
- Mice, Knockout
- Pneumonia, Bacterial/drug therapy
- Pneumonia, Bacterial/enzymology
- Pneumonia, Bacterial/genetics
- Pneumonia, Bacterial/immunology
- Pneumonia, Bacterial/pathology
- Prostaglandin D2/pharmacology
- Prostaglandin D2/therapeutic use
- Pseudomonas Infections/drug therapy
- Pseudomonas Infections/enzymology
- Pseudomonas Infections/genetics
- Pseudomonas Infections/immunology
- Pseudomonas aeruginosa/immunology
- Transcription Factor AP-1/immunology
- Transcription Factor AP-1/metabolism
- Tumor Suppressor Protein p53/immunology
- Tumor Suppressor Protein p53/metabolism
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Affiliation(s)
- Myungsoo Joo
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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250
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Navara KJ, Trainor BC, Nelson RJ. Photoperiod alters macrophage responsiveness, but not expression of Toll-like receptors in Siberian hamsters. Comp Biochem Physiol A Mol Integr Physiol 2007; 148:354-9. [PMID: 17588795 DOI: 10.1016/j.cbpa.2007.05.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 05/07/2007] [Accepted: 05/14/2007] [Indexed: 01/27/2023]
Abstract
Defense against pathogens is a critical component of comparative and ecological biology. However, pathogen recognition, a process necessary for the facilitation of systemic immune response, remains understudied in a comparative context, yet could provide insight into how the immune system interacts with pathogens in variable environments. We examined pathogen recognition by macrophages in relation to an ecological variable, day length, in Siberian hamsters (Phodopus sungorus). Because peritoneal macrophages collected in long, summer-like day lengths are more responsive to a lipopolysaccharide (LPS) challenge compared to macrophages collected during short, winter-like day lengths, we hypothesized that these functional differences are mediated by variation in pathogen recognition, which occurs through binding to Toll-like receptors (TLRs). We predicted that expression of TLR2 and 4, the receptors that bind and respond specifically to LPS, would be upregulated in long vs. short days, and that expression of these receptors would reflect macrophage responsiveness to LPS. Macrophages collected during long days were again more responsive to LPS challenge compared to short-day macrophages; however, TLR2 and TLR4 expression was similar between photoperiods and were unrelated to our measure of macrophage responsiveness suggesting that other downstream intracellular mechanisms may be responsible for photoperiod-based variation in macrophage responsiveness in this species.
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Affiliation(s)
- Kristen J Navara
- Departments of Psychology and Neuroscience, Institute of Behavioral Medicine Research, The Ohio State University, Columbus, OH 43210, USA.
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