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Trovato FM, Zia R, Artru F, Mujib S, Jerome E, Cavazza A, Coen M, Wilson I, Holmes E, Morgan P, Singanayagam A, Bernsmeier C, Napoli S, Bernal W, Wendon J, Miquel R, Menon K, Patel VC, Smith J, Atkinson SR, Triantafyllou E, McPhail MJW. Lysophosphatidylcholines modulate immunoregulatory checkpoints in peripheral monocytes and are associated with mortality in people with acute liver failure. J Hepatol 2023; 78:558-573. [PMID: 36370949 DOI: 10.1016/j.jhep.2022.10.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 11/11/2022]
Abstract
BACKGROUND & AIMS Acute liver failure (ALF) is a life-threatening disease characterised by high-grade inflammation and immunoparesis, which is associated with a high incidence of death from sepsis. Herein, we aimed to describe the metabolic dysregulation in ALF and determine whether systemic immune responses are modulated via the lysophosphatidylcholine (LPC)-autotaxin (ATX)-lysophosphatidylcholinic acid (LPA) pathway. METHODS Ninety-six individuals with ALF, 104 with cirrhosis, 31 with sepsis and 71 healthy controls (HCs) were recruited. Pathways of interest were identified by multivariate statistical analysis of proton nuclear magnetic resonance spectroscopy and untargeted ultraperformance liquid chromatography-mass spectrometry-based lipidomics. A targeted metabolomics panel was used for validation. Peripheral blood mononuclear cells were cultured with LPA 16:0, 18:0, 18:1, and their immune checkpoint surface expression was assessed by flow cytometry. Transcript-level expression of the LPA receptor (LPAR) in monocytes was investigated and the effect of LPAR antagonism was also examined in vitro. RESULTS LPC 16:0 was highly discriminant between ALF and HC. There was an increase in ATX and LPA in individuals with ALF compared to HCs and those with sepsis. LPCs 16:0, 18:0 and 18:1 were reduced in individuals with ALF and were associated with a poor prognosis. Treatment of monocytes with LPA 16:0 increased their PD-L1 expression and reduced CD155, CD163, MerTK levels, without affecting immune checkpoints on T and NK/CD56+T cells. LPAR1 and 3 antagonism in culture reversed the effect of LPA on monocyte expression of MerTK and CD163. MerTK and CD163, but not LPAR genes, were differentially expressed and upregulated in monocytes from individuals with ALF compared to controls. CONCLUSION Reduced LPC levels are biomarkers of poor prognosis in individuals with ALF. The LPC-ATX-LPA axis appears to modulate innate immune response in ALF via LPAR1 and LPAR3. Further investigations are required to identify novel therapeutic agents targeting these receptors. IMPACT AND IMPLICATIONS We identified a metabolic signature of acute liver failure (ALF) and investigated the immunometabolic role of the lysophosphatidylcholine-autotaxin-lysophosphatidylcholinic acid pathway, with the aim of finding a mechanistic explanation for monocyte behaviour and identifying possible therapeutic targets (to modulate the systemic immune response in ALF). At present, no selective immune-based therapies exist. We were able to modulate the phenotype of monocytes in vitro and aim to extend these findings to murine models of ALF as a next step. Future therapies may be based on metabolic modulation; thus, the role of specific lipids in this pathway require elucidation and the relative merits of autotaxin inhibition, lysophosphatidylcholinic acid receptor blockade or lipid-based therapies need to be determined. Our findings begin to bridge this knowledge gap and the methods used herein could be useful in identifying therapeutic targets as part of an experimental medicine approach.
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Affiliation(s)
- Francesca M Trovato
- Department of Inflammation Biology, School of Immunology and Microbial Sciences, Kings College London, UK; Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK.
| | - Rabiya Zia
- Section of Hepatology and Gastroenterology, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College, London, UK
| | - Florent Artru
- Department of Inflammation Biology, School of Immunology and Microbial Sciences, Kings College London, UK; Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
| | - Salma Mujib
- Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
| | - Ellen Jerome
- Department of Inflammation Biology, School of Immunology and Microbial Sciences, Kings College London, UK; Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
| | - Anna Cavazza
- Department of Inflammation Biology, School of Immunology and Microbial Sciences, Kings College London, UK; Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
| | - Muireann Coen
- Section of Hepatology and Gastroenterology, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College, London, UK; Oncology Safety, Clinical Pharmacology & Safety Sciences, R&D, Astra Zeneca, Cambridge, UK
| | - Ian Wilson
- Section of Hepatology and Gastroenterology, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College, London, UK
| | - Elaine Holmes
- Section of Hepatology and Gastroenterology, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College, London, UK
| | - Phillip Morgan
- Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
| | - Arjuna Singanayagam
- Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK; Infection Clinical Academic Group, St.George's University of London, UK
| | - Christine Bernsmeier
- Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK; Department of Biomedicine, University of Basel and University Centre for Gastrointestinal and Liver Diseases, Basel, Switzerland
| | - Salvatore Napoli
- Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
| | - William Bernal
- Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
| | - Julia Wendon
- Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
| | - Rosa Miquel
- Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
| | - Krishna Menon
- Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
| | - Vishal C Patel
- Department of Inflammation Biology, School of Immunology and Microbial Sciences, Kings College London, UK; Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK; The Roger Williams Institute of Hepatology London, Foundation for Liver Research, London, UK
| | - John Smith
- Anaesthetics, Critical Care, Emergency and Trauma Research Delivery Unit, Kings College Hospital, London, UK
| | - Stephen R Atkinson
- Section of Hepatology and Gastroenterology, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College, London, UK
| | - Evangelos Triantafyllou
- Section of Hepatology and Gastroenterology, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College, London, UK
| | - Mark J W McPhail
- Department of Inflammation Biology, School of Immunology and Microbial Sciences, Kings College London, UK; Institute of Liver Studies, Kings College Hospital, Denmark Hill, London, UK
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Lysophosphatidylcholine acyltransferase 2 (LPCAT2) co-localises with TLR4 and regulates macrophage inflammatory gene expression in response to LPS. Sci Rep 2020; 10:10355. [PMID: 32587324 PMCID: PMC7316826 DOI: 10.1038/s41598-020-67000-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 05/06/2020] [Indexed: 12/24/2022] Open
Abstract
Despite extensive investigations, an effective treatment for sepsis remains elusive and a better understanding of the inflammatory response to infection is required to identify potential new targets for therapy. In this study we have used RNAi technology to show, for the first time, that the inducible lysophosphatidylcholine acyltransferase 2 (LPCAT2) plays a key role in macrophage inflammatory gene expression in response to stimulation with bacterial ligands. Using siRNA- or shRNA-mediated knockdown, we demonstrate that, in contrast to the constitutive LPCAT1, LPCAT2 is required for macrophage cytokine gene expression and release in response to TLR4 and TLR2 ligand stimulation but not for TLR-independent stimuli. In addition, cells transfected to overexpress LPCAT2 exhibited increased expression of inflammatory genes in response to LPS and other bacterial ligands. Furthermore, we have used immunoprecipitation and Western blotting to show that in response to LPS, LPCAT2, but not LPCAT1, rapidly associates with TLR4 and translocates to membrane lipid raft domains. Our data thus suggest a novel mechanism for the regulation of inflammatory gene expression in response to bacterial stimuli and highlight LPCAT2 as a potential therapeutic target for development of anti-inflammatory and anti-sepsis therapies.
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Llewellyn A, Foey A. Probiotic Modulation of Innate Cell Pathogen Sensing and Signaling Events. Nutrients 2017; 9:E1156. [PMID: 29065562 PMCID: PMC5691772 DOI: 10.3390/nu9101156] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/06/2017] [Accepted: 10/09/2017] [Indexed: 02/07/2023] Open
Abstract
There is a growing body of evidence documenting probiotic bacteria to have a beneficial effect to the host through their ability to modulate the mucosal immune system. Many probiotic bacteria can be considered to act as either immune activators or immune suppressors, which have appreciable influence on homeostasis, inflammatory- and suppressive-immunopathology. What is becoming apparent is the ability of these probiotics to modulate innate immune responses via direct or indirect effects on the signaling pathways that drive these activatory or suppressive/tolerogenic mechanisms. This review will focus on the immunomodulatory role of probiotics on signaling pathways in innate immune cells: from positive to negative regulation associated with innate immune cells driving gut mucosal functionality. Research investigations have shown probiotics to modulate innate functionality in many ways including, receptor antagonism, receptor expression, binding to and expression of adaptor proteins, expression of negative regulatory signal molecules, induction of micro-RNAs, endotoxin tolerisation and finally, the secretion of immunomodulatory proteins, lipids and metabolites. The detailed understanding of the immunomodulatory signaling effects of probiotic strains will facilitate strain-specific selective manipulation of innate cell signal mechanisms in the modulation of mucosal adjuvanticity, immune deviation and tolerisation in both healthy subjects and patients with inflammatory and suppressive pathology.
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Affiliation(s)
- Amy Llewellyn
- School of Biomedical & Healthcare Sciences, Plymouth University Peninsula Schools of Medicine & Dentistry, Drake Circus, Plymouth PL4 8AA, UK.
- Menzies School of Health Research, John Mathews Building (Building 58), Royal Darwin Hospital Campus, PO Box 41096, Casuarina NT0811, Australia.
| | - Andrew Foey
- School of Biomedical & Healthcare Sciences, Plymouth University Peninsula Schools of Medicine & Dentistry, Drake Circus, Plymouth PL4 8AA, UK.
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Abate W, Sattar AA, Liu J, Conway ME, Jackson SK. Evaluation of recombinant factor C assay for the detection of divergent lipopolysaccharide structural species and comparison with Limulus amebocyte lysate-based assays and a human monocyte activity assay. J Med Microbiol 2017; 66:888-897. [DOI: 10.1099/jmm.0.000510] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Wondwossen Abate
- Centre for Biomedical Research, School of Biomedical and Healthcare Sciences, Peninsula Schools of Medicine and Dentistry, Plymouth University, Plymouth, UK
| | - Anas A. Sattar
- Centre for Biomedical Research, School of Biomedical and Healthcare Sciences, Peninsula Schools of Medicine and Dentistry, Plymouth University, Plymouth, UK
| | - Jian Liu
- Academic Unit of Ophthalmology, University of Bristol, Bristol, UK
| | - Myra E. Conway
- Centre for Research in Biosciences, Faculty of Health and Life Sciences, University of the West of England, Bristol, UK
| | - Simon K. Jackson
- Centre for Biomedical Research, School of Biomedical and Healthcare Sciences, Peninsula Schools of Medicine and Dentistry, Plymouth University, Plymouth, UK
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Song L, Duan P, Gan Y, Li P, Zhao C, Xu J, Zhang Z, Zhou Q. Silencing LPAATβ inhibits tumor growth of cisplatin-resistant human osteosarcoma in vivo and in vitro. Int J Oncol 2016; 50:535-544. [DOI: 10.3892/ijo.2016.3820] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/06/2016] [Indexed: 11/06/2022] Open
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Ahn WG, Jung JS, Kwon HY, Song DK. Alteration of Lysophosphatidylcholine-Related Metabolic Parameters in the Plasma of Mice with Experimental Sepsis. Inflammation 2016; 40:537-545. [DOI: 10.1007/s10753-016-0500-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Helley M, Abate W, Jackson S, Bennett J, Thompson S. The expression of Toll-like receptor 4, 7 and co-receptors in neurochemical sub-populations of rat trigeminal ganglion sensory neurons. Neuroscience 2015; 310:686-98. [DOI: 10.1016/j.neuroscience.2015.09.069] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/03/2015] [Accepted: 09/25/2015] [Indexed: 12/12/2022]
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Brown J, Wallet MA, Krastins B, Sarracino D, Goodenow MM. Proteome bioprofiles distinguish between M1 priming and activation states in human macrophages. J Leukoc Biol 2010; 87:655-62. [PMID: 20007246 DOI: 10.1189/jlb.0809570] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Macrophage activation is a dynamic process that results in diverse functional outcomes ranging from immunoregulation to inflammation. The proinflammatory, or M1, response is a complex, bimodal progression composed of a "prime," classically through IFN-gamma, and "trigger," such as LPS. To characterize the physiological response of M1 activation, a systems biology approach was applied to determine the intracellular proteome bioprofiles of IFN-gamma-and LPS-treated primary human macrophages. Our goal was to develop intracellular proteomic fingerprints to serve as novel correlates of macrophage priming and/or activation to augment the existing approaches of analyzing secreted cytokines and cell-surface protein expression. The majority of the proteome, approximately 78%, remained stable during activation, representing the core proteome. In contrast, three distinct patterns defined response proteomes: IFN-gamma-specific, LPS-specific, or IFN-gamma- and LPS-shared or M1-specific. Although steady-state expression levels of proteins involved in energy metabolism and immune response were increased during priming and triggering, changes in protein and fatty acid metabolism, signaling, and transport pathways were most apparent. Unique proteomic fingerprints distinguish among IFN-gamma-specific, LPS-specific, or M1-specific activation states and provide a clear molecular, archeological profile to infer recent history of cells, as well as correlates for chronic macrophage activation in health and disease.
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Affiliation(s)
- Joseph Brown
- Department of Pathology Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida 32610-3633, USA
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Jha RK, Ma Q, Sha H, Palikhe M. Protective effect of resveratrol in severe acute pancreatitis-induced brain injury. Pancreas 2009; 38:947-53. [PMID: 19696693 DOI: 10.1097/mpa.0b013e3181b2bc54] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVES The aim of this study was to study the effects of resveratrol on severe acute pancreatitis (SAP)-induced brain injury. METHODS Ninety-six male Sprague-Dawley rats were randomly divided into 4 equal groups: sham operation, SAP, resveratrol-treated (RES), and dexamethasone-treated. Each group was evaluated at 3, 6, and 12 hours. Levels of serum myelin basic protein and zonula occludens 1 (Zo-1) were determined by enzyme-linked immunosorbent assay. The brain and pancreatic tissues were examined using electron microscopy. Expressions of Bax, Bcl-2, and caspase-3 were observed using immunohistochemistry, reverse transcriptase polymerase chain reaction, and Western blotting. Cytochrome c was detected using Western blotting alone. RESULTS Myelin basic protein and Zo-1 levels of the RES group were lower than the SAP group at all time points (P < 0.05). The RES group had significantly improved pathologic brain, increase in Bcl-2 expression, and decrease in Bax and caspases-3 expressions compared with the SAP group. CONCLUSIONS The degradation of Zo-1 is involved in the pathophysiology of brain injury in SAP; MBP can be used as a marker of brain injury in SAP. The protective effect of resveratrol might be associated with the up-regulation of Bcl-2 and down-regulation of Bax and caspase-3.
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Affiliation(s)
- Rajiv Kumar Jha
- Department of Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, People's Republic of China.
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Cunningham TJ, Yao L, Lucena A. Product inhibition of secreted phospholipase A2 may explain lysophosphatidylcholines' unexpected therapeutic properties. JOURNAL OF INFLAMMATION-LONDON 2008; 5:17. [PMID: 18945345 PMCID: PMC2580763 DOI: 10.1186/1476-9255-5-17] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Accepted: 10/22/2008] [Indexed: 11/24/2022]
Abstract
Background Lysophosphatidylcholines (lysoPCs) are products of phospholipase A2 (PLA2) enzyme activity, and like the enzyme, have a direct role in toxic inflammatory responses in variety of organ systems. Paradoxically, reduced plasma lysoPC levels have been noted in sepsis patients and systemic treatment with lysoPCs is therapeutic in rodent models of sepsis and ischemia. These observations suggest that elevation of plasma levels of these lipids can actually help to relieve serious inflammatory conditions. We demonstrate that specific lysoPCs act as uncompetitive product inhibitors of plasma secreted PLA2 enzymes (sPLA2s), especially under conditions of elevated enzyme activity, thus providing a feedback mechanism for the observed anti-inflammatory effects of these compounds. Methods Thin layer chromatography and mass spectroscopy were used to estimate total lysoPC concentration and the relative contributions of different lysoPC species in rat plasma samples. Kinetic studies of sPLA2 enzyme activity were conducted on these samples ex vivo and on purified group IA sPLA2 in vitro after addition of specific lysoPC species to the reaction mixture. Enzyme activity was also measured in plasma samples of rats injected with these same lysoPCs. Results Palmitoyl (16:0), stearoyl (18:0) are the most abundant lysoPCs in rat plasma consistent with other reports. Kinetic studies demonstrated that both were uncompetitive inhibitors of plasma sPLA2 enzyme activity. In vitro experiments with group IA sPLA2 confirmed the inhibition and the kinetic properties of these lysoPC species. Decanoyl lysoPC (10:0), which was not detected in plasma, did not inhibit enzyme activity in vitro. LysoPC injections into normal rats resulted in "buffering" of plasma sPLA2 activity in a narrow low range, consistent with the activity-dependent inhibition suggested by the ex vivo and in vitro experiments. Conclusion The results may explain the efficacy of lysoPC therapy during periods of elevated inflammatory activity and further highlight the utility uncompetitive enzyme inhibitors. In this case, the inhibitor is a product of the enzyme reaction, and therefore represents an example of activity-driven feedback inhibition.
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Affiliation(s)
- Timothy J Cunningham
- Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA.
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Jackson SK, Abate W, Tonks AJ. Lysophospholipid acyltransferases: novel potential regulators of the inflammatory response and target for new drug discovery. Pharmacol Ther 2008; 119:104-14. [PMID: 18538854 DOI: 10.1016/j.pharmthera.2008.04.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Molecular and biochemical analyses of membrane phospholipids have revealed that, in addition to their physico-chemical properties, the metabolites of phospholipids play a crucial role in the recognition, signalling and responses of cells to a variety of stimuli. Such responses are mediated in large part by the removal and/or addition of different acyl chains to provide different phospholipid molecular species. The reacylation reactions, catalysed by specific acyltransferases control phospholipid composition and the availability of the important mediators free arachidonic acid and lysophospholipids. Lysophospholipid acyltransferases are therefore key control points for cellular responses to a variety of stimuli including inflammation. Regulation or manipulation of lysophospholipid acyltransferases may thus provide important mechanisms for novel anti-inflammatory therapies. This review will highlight mammalian lysophospholipid acyltransferases with particular reference to the potential role of lysophosphatidylcholine acyltransferase and its substrates in sepsis and other inflammatory conditions and as a potential target for novel anti-inflammatory therapies.
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Affiliation(s)
- Simon K Jackson
- Centre for Research in Biomedicine, Faculty of Health and Life Sciences, Frenchay Campus, University of the West of England, Bristol, UK.
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Jackson SK, Abate W, Parton J, Jones S, Harwood JL. Lysophospholipid metabolism facilitates Toll-like receptor 4 membrane translocation to regulate the inflammatory response. J Leukoc Biol 2008; 84:86-92. [PMID: 18403647 DOI: 10.1189/jlb.0907601] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Sepsis, an overwhelming inflammatory response to infection, is a major cause of morbidity and mortality worldwide and has no specific therapy. Phospholipid metabolites, such as lysophospholipids, have been shown to regulate inflammatory responses in sepsis, although their mechanism of action is not well understood. The phospholipid-metabolizing enzymes, lysophospholipid acyltransferases, control membrane phospholipid composition, function, and the inflammatory responses of innate immune cells. Here, we show that lysophosphatidylcholine acyltransferase (LPCAT) regulates inflammatory responses to LPS and other microbial stimuli. Specific inhibition of LPCAT down-regulated inflammatory cytokine production in monocytes and epithelial cells by preventing translocation of TLR4 into membrane lipid raft domains. Our observations demonstrate a new regulatory mechanism that facilitates the innate immune responses to microbial molecular patterns and provide a basis for the anti-inflammatory activity observed in many phospholipid metabolites. This provides the possibility of the development of new classes of anti-inflammatory and antisepsis agents.
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Affiliation(s)
- Simon K Jackson
- Centre for Research in Biomedicine, University of the West of England, Bristol, BS16 1QY, UK.
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Buhtoiarov IN, Lum HD, Berke G, Sondel PM, Rakhmilevich AL. Synergistic activation of macrophages via CD40 and TLR9 results in T cell independent antitumor effects. THE JOURNAL OF IMMUNOLOGY 2006; 176:309-18. [PMID: 16365423 DOI: 10.4049/jimmunol.176.1.309] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have previously shown that macrophages (Mphi) can be activated by CD40 ligation to become cytotoxic against tumor cells in vitro. Here we show that treatment of mice with agonistic anti-CD40 mAb (anti-CD40) induced up-regulation of intracellular TLR9 in Mphi and primed them to respond to CpG-containing oligodeoxynucleotides (CpG), resulting in synergistic activation. The synergy between anti-CD40 and CpG was evidenced by increased production of IFN-gamma, IL-12, TNF-alpha, and NO by Mphi, as well as by augmented apoptogenic effects of Mphi against tumor cells in vitro. The activation of cytotoxic Mphi after anti-CD40 plus CpG treatment was dependent on IFN-gamma but not TNF-alpha or NO, and did not require T cells and NK cells. Anti-CD40 and CpG also synergized in vivo in retardation of tumor growth in both immunocompetent and immunodeficient mice. Inactivation of Mphi in SCID/beige mice by silica treatment abrogated the antitumor effect. Taken together, our results show that Mphi can be activated via CD40/TLR9 ligation to kill tumor cells in vitro and inhibit tumor growth in vivo even in immunocompromised tumor-bearing hosts, indicating that this Mphi-based immunotherapeutic strategy may be appropriate for clinical testing.
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Affiliation(s)
- Ilia N Buhtoiarov
- Department of Human Oncology and Comprehensive Cancer Center, University of Wisconsin, Madison, WI 53792, USA.
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N/A. N/A. Shijie Huaren Xiaohua Zazhi 2005; 13:2667-2671. [DOI: 10.11569/wcjd.v13.i22.2667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/26/2023] Open
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Jackson SK, Parton J. Lysophospholipid acyltransferases in monocyte inflammatory responses and sepsis. Immunobiology 2005; 209:31-8. [PMID: 15481138 DOI: 10.1016/j.imbio.2004.04.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Acyltransferases are important in the regulation of membrane phospholipid fatty acyl composition and together with phospholipase A2 enzymes control arachidonic acid incorporation and remodelling within phospholipids. In addition, monocyte and macrophage acyltransferase activity has been shown to respond to various inflammatory cytokines under conditions that can induce enhanced cellular responses. Work in our laboratory indicates that the enzyme lysophosphatidylcholine acyltransferase may mediate the priming reactions of monocytes to the cytokine interferon-gamma. Our recent studies suggest that this enzyme might also affect the responses of monocytes to the bacterial agent lipopolysaccharide that may be important in the development of sepsis. This article summarises the relationship between monocyte lysophosphatidylcholine acyltransferase, lipopolysaccharide and sepsis.
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Affiliation(s)
- Simon K Jackson
- Department of Medical Microbiology, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, Wales, UK.
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Parks BW, Gambill GP, Lusis AJ, Kabarowski JHS. Loss of G2A promotes macrophage accumulation in atherosclerotic lesions of low density lipoprotein receptor-deficient mice. J Lipid Res 2005; 46:1405-15. [PMID: 15834123 DOI: 10.1194/jlr.m500085-jlr200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Lysophosphatidylcholine (LPC) is considered a major proatherogenic component of oxidized low density lipoprotein based on its proinflammatory actions in vitro. LPC stimulates macrophage and T-cell chemotaxis via the G protein-coupled receptor G2A and may thus promote inflammatory cell infiltration during atherosclerotic lesion development. However, G2A also mediates proapoptotic effects of LPC and may therefore promote the death of inflammatory cells within developing lesions. To determine how these effects of LPC modify atherogenesis, we examined atherosclerotic lesion development in G2A-sufficient and G2A-deficient low density lipoprotein receptor knockout mice. Although LPC species capable of activating G2A-dependent responses were increased during lesion development, G2A-deficient mice developed lesions similar in size to those in their G2A-sufficient counterparts. Loss of G2A during atherosclerotic lesion development did not reduce macrophage and T-cell infiltration but instead resulted in increased lesional macrophage content associated with reduced numbers of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeled cells and decreased collagen deposition. These data indicate that the ability of LPC to stimulate macrophage and T-cell chemotaxis via G2A is not manifested in vivo and that G2A-mediated proapoptotic rather than chemotactic action is most penetrant during atherogenesis and may modify the stability of atherosclerotic lesions by promoting macrophage death.
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Affiliation(s)
- Brian W Parks
- Department of Microbiology, University of Alabama, Birmingham, AL 35294-2170, USA
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Neville NT, Parton J, Harwood JL, Jackson SK. The activities of monocyte lysophosphatidylcholine acyltransferase and coenzyme A-independent transacylase are changed by the inflammatory cytokines tumor necrosis factor alpha and interferon gamma. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1733:232-8. [PMID: 15863370 DOI: 10.1016/j.bbalip.2004.12.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2004] [Revised: 12/17/2004] [Accepted: 12/20/2004] [Indexed: 11/26/2022]
Abstract
Alteration of membrane phospholipid fatty acid compositions has been shown to be important for leukocyte inflammatory responses. Such modification of the molecular species of these lipid classes requires deacylation and reacylation reactions and for phosphatidylcholines, lysophosphatidylcholine acyltransferase (LPCAT) and a coenzyme A-independent transacylase (CoAIT) can each be involved. Since previous studies have shown a significant IFNgamma- and TNFalpha-induced modification of phosphatidylcholine species, we have examined whether these inflammatory cytokines alter the activity of reacylation enzymes in the human monocyte cell line MonoMac 6 (MM6). IFN-gamma caused a significant increase in the activity of the LPCAT and CoAIT enzymes in the microsomal fraction at concentrations and over a time-course consistent with an important role for these enzymes in the sensitization (priming) of monocytes. In contrast, TNFalpha was found to significantly increase the activity of the CoAIT by 50% over controls in MM6 cells after 30 min incubation with the cytokine, but decreased LPCAT activity by 65% after 24 h incubation. Such data imply that CoAIT is important for the remodelling of phospholipid composition, which is seen during the acute response of cells to TNFalpha. The results provide further information to emphasise the role of acyltransferases as part of the molecular mechanism underlying inflammation.
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Beermann C, Möbius M, Winterling N, Schmitt JJ, Boehm G. sn-Position determination of phospholipid-linked fatty acids derived from erythrocytes by liquid chromatography electrospray ionization ion-trap mass spectrometry. Lipids 2005; 40:211-8. [PMID: 15884770 DOI: 10.1007/s11745-005-1377-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The sn-position of FA in membrane lipids has an influence on the physiological function of cells, is predictive for diseases, and therefore is useful for diagnostics. The current study compares the compositions of acyl chain substituents in the sn-1 and sn-2 positions of the glycerol backbones of phospholipids derived from human erythrocytes by using RP-HPLC coupled with on-line electrospray ionization ion trap MS. Preferential loss of the acyl group in the sn-1 position was used to determine the degree of regiospecific preference exhibited by the phospholipid molecules. The identities of the molecular species and the positions of the acyl substituents were identified using product-ion spectra of major precursor ions selected from the mass spectra averaged across peaks in the total ion chromatogram. Saturated FA were found to be located mainly in the sn-1 position of the glycerol backbones of erythrocyte phospholipids, whereas PUFA were found primarily in the sn-2 position. All measured phospholipids revealed palmitic acid (16:0) at the sn-1 position. Linoleic acid (18:2n-6) and arachidonic acid (20:4n-6) were found to be attached exclusively to the sn-2 position of the backbone, whereas eicosadienoic (20:2n-6) and eicosatrienoic acid (20:3n-9) occurred in both positions of the backbone of PC. Oleic (18:1n-9), linoleic (18:2n-6), and octadecatrienoic (18:3) acids of PE and PS were linked to both positions. Lignoceric acid (24:1 n-9) was found to be strictly localized at the sn-2 position, whereas nervonic (24:1n-9) acid of PS was associated with both positions of the backbone. A detailed analysis of the blood cell membrane lipids by MS might be helpful to characterize postprandial kinetics of pharmacological or dietary lipid applications, as well as environmental influences on cell membranes.
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