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Tandon A, Harioudh MK, Verma NK, Saroj J, Gupta A, Pant G, Tripathi JK, Kumar A, Kumari T, Tripathi AK, Mitra K, Ghosh JK. Characterization of a Myeloid Differentiation Factor 2-Derived Peptide that Facilitates THP-1 Macrophage-Mediated Phagocytosis of Gram-Negative Bacteria. ACS Infect Dis 2024; 10:845-857. [PMID: 38363869 DOI: 10.1021/acsinfecdis.3c00274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2024]
Abstract
Myeloid differentiation factor 2 (MD2), the TLR4 coreceptor, has been shown to possess opsonic activity and has been implicated in phagocytosis and intracellular killing of Gram-negative bacteria. However, any MD2 protein segment involved in phagocytosis of Gram-negative bacteria is not yet known. A short synthetic MD2 segment, MD54 (amino acid regions 54 to 69), was shown to interact with a Gram-negative bacterial outer membrane component, LPS, earlier. Furthermore, the MD54 peptide induced aggregation of LPS and facilitated its internalization in THP-1 cells. Currently, it has been investigated if MD2-derived MD54 possesses any opsonic property and role in phagocytosis of Gram-negative bacteria. Remarkably, we observed that MD54 facilitated agglutination of Gram-negative bacteria, Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC BAA-427), but not of Gram-positive bacteria, Bacillus subtilis (ATCC 6633) and Staphylococcus aureus (ATCC 25923). The MD54-opsonized Gram-negative bacteria internalized within PMA-treated THP-1 cells and were killed over a longer incubation period. However, both internalization and intracellular killing of the MD54-opsonized Gram-negative bacteria within THP-1 phagocytes were appreciably inhibited in the presence of a phagocytosis inhibitor, cytochalasin D. Furthermore, MD54 facilitated the clearance of Gram-negative bacteria E. coli (ATCC 25922) and P. aeruginosa (ATCC BAA-427) from the infected BALB/c mice whereas an MD54 analog, MMD54, was inactive. Overall, for the first time, the results revealed that a short MD2-derived peptide can specifically agglutinate Gram-negative bacteria, act as an opsonin for these bacteria, and facilitate their phagocytosis by THP-1 phagocytes. The results suggest that the MD54 segment could have a crucial role in MD2-mediated host-pathogen interaction involving the Gram-negative bacteria.
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Affiliation(s)
- Anshika Tandon
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Munesh Kumar Harioudh
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Neeraj Kumar Verma
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Jyotshana Saroj
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
- Academy of Scientific and Innovative Research (AcSIR), New Delhi 110001, India
| | - Arvind Gupta
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
- Academy of Scientific and Innovative Research (AcSIR), New Delhi 110001, India
| | - Garima Pant
- Electron Microscopy Unit, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Jitendra Kumar Tripathi
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Amit Kumar
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Tripti Kumari
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Amit Kumar Tripathi
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Kalyan Mitra
- Electron Microscopy Unit, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Jimut Kanti Ghosh
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
- Academy of Scientific and Innovative Research (AcSIR), New Delhi 110001, India
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Wang Y, Yang LG, Feng GP, Yao ZL, Li SH, Zhou JF, Fang WH, Chen YH, Li XC. PvML1 suppresses bacterial infection by recognizing LPS and regulating AMP expression in shrimp. Front Immunol 2022; 13:1088862. [PMID: 36643915 PMCID: PMC9832027 DOI: 10.3389/fimmu.2022.1088862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 12/06/2022] [Indexed: 12/29/2022] Open
Abstract
Toll and Toll-like receptors (TLRs) play essential roles in the innate immunity of Drosophila and mammals. Recent studies have revealed the presence of Toll-mediated immune signaling pathways in shrimp. However, the recognition and activation mechanism of Toll signaling pathways in crustaceans remain poorly understood due to the absence of key recognition molecules, such as peptidoglycan recognition proteins. Here, a novel MD2-related lipid-recognition (ML) member named PvML1 was characterized in Penaeus vannamei. We found that PvML1 shared a similar 3D structure with human MD2 that could specifically recognize lipopolysaccharides (LPS) participating in LPS-mediated TLR4 signaling. PvML1 was highly expressed in hemocytes and remarkably upregulated after Vibrio parahemolyticus challenge. Furthermore, the binding and agglutinating assays showed that PvML1 possessed strong binding activities to LPS and its key portion lipid A as well as Vibrio cells, and the binding of PvML1 with bacterial cells led to the agglutination of bacteria, suggesting PvML1 may act as a potential pathogen recognition protein upon interaction with LPS. Besides, coating V. parahemolyticus with recombinant PvML1 promoted bacterial clearance in vivo and increased the survival rate of bacterium-challenged shrimp. This result was further confirmed by RNAi experiments. The knockdown of PvML1 remarkably suppressed the clearance of bacteria in hemolymph and decreased the survival rate of infected shrimp. Meanwhile, the silencing of PvML1 severely impaired the expression of a few antimicrobial peptides (AMPs). These results demonstrated the significant correlation of bacterial clearance mediated by PvML1 with the AMP expression. Interestingly, we found that PvML1 interacted with the extracellular region of PvToll2, which had been previously shown to participate in bacterial clearance by regulating AMP expression. Taken together, the proposed antibacterial model mediated by PvML1 might be described as follows. PvML1 acted as a potential recognition receptor for Gram-negative bacteria by binding to LPS, and then it activated PvToll2-mediated signaling pathway by interacting with PvToll2 to eliminate invading bacteria through producing specific AMPs. This study provided new insights into the recognition and activation mechanism of Toll signaling pathways of invertebrates and the defense functions of ML members.
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Affiliation(s)
- Yue Wang
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China,Laboratory of Marine Biological Resources and Molecular Engineering, Marine Science and Technology College, Zhejiang Ocean University, Zhoushan, China
| | - Li-Guo Yang
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Guang-Peng Feng
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Zong-Li Yao
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Shou-Hu Li
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Jun-Fang Zhou
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Wen-Hong Fang
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Yi-Hong Chen
- Key Laboratory for Healthy and Safe Aquaculture, Institute of Modern Aquaculture Science and Engineering (IMASE), College of Life Science, South China Normal University, Guangzhou, China,Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, China,*Correspondence: Yi-Hong Chen, ; Xin-Cang Li,
| | - Xin-Cang Li
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China,*Correspondence: Yi-Hong Chen, ; Xin-Cang Li,
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Su K, Bo L, Jiang C, Deng X, Zhao YY, Minshall RD, Hu G. TLR4 is required for macrophage efferocytosis during resolution of ventilator-induced lung injury. Am J Physiol Lung Cell Mol Physiol 2021; 321:L787-L801. [PMID: 34405715 DOI: 10.1152/ajplung.00226.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanical ventilation is a life-sustaining therapy for patients with respiratory failure but can cause further lung damage known as ventilator-induced lung injury (VILI). However, the intrinsic molecular mechanisms underlying recovery of VILI remain unknown. Phagocytosis of apoptotic cells (also known as efferocytosis) is a key mechanism orchestrating successful resolution of inflammation. Here we show the positive regulation of macrophage Toll-like receptor (TLR) 4 in efferocytosis and resolution of VILI. Mice were depleted of alveolar macrophages and then subjected to injurious ventilation (tidal volume, 20 mL/kg) for 4 h. On day 1 after mechanical ventilation, Tlr4+/+ or Tlr4-/- bone marrow-derived macrophages (BMDMs) were intratracheally administered to alveolar macrophage-depleted mice. We observed that mice depleted of alveolar macrophages exhibited defective resolution of neutrophilic inflammation, exuded protein, lung edema, and lung tissue injury after ventilation, whereas these delayed responses were reversed by administration of Tlr4+/+ BMDMs. Importantly, these proresolving effects by Tlr4+/+ BMDMs were abolished in mice receiving Tlr4-/- BMDMs. The number of macrophages containing apoptotic cells or bodies in bronchoalveolar lavage fluid was much less in mice receiving Tlr4-/- BMDMs than that in those receiving Tlr4+/+ BMDMs. Macrophage TLR4 deletion facilitated a disintegrin and metalloprotease 17 maturation and enhanced Mer cleavage in response to mechanical ventilation. Heat shock protein 70 dramatically increased Mer tyrosine kinase surface expression, phagocytosis of apoptotic neutrophils, and rescued the inflammatory phenotype in alveolar macrophage-depleted mice receiving Tlr4+/+ BMDMs, but not Tlr4-/- BMDMs. Our results suggest that macrophage TLR4 promotes resolution of VILI via modulation of Mer-mediated efferocytosis.
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Affiliation(s)
- Kai Su
- Department of Anesthesiology, University of Illinois College of Medicine, Chicago, Illinois.,Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Lulong Bo
- Faculty of Anesthesiology, Changhai Hospital, Shanghai, People's Republic of China
| | - Chunling Jiang
- Department of Anesthesiology, University of Illinois College of Medicine, Chicago, Illinois
| | - Xiaoming Deng
- Faculty of Anesthesiology, Changhai Hospital, Shanghai, People's Republic of China
| | - You-Yang Zhao
- Program for Lung and Vascular Biology, Stanley Manne Children's Research Institute, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois.,Division of Critical Care, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Richard D Minshall
- Department of Anesthesiology, University of Illinois College of Medicine, Chicago, Illinois.,Department of Pharmacology and Regenerative Medicine, University of Illinois College of Medicine, Chicago, Illinois
| | - Guochang Hu
- Department of Anesthesiology, University of Illinois College of Medicine, Chicago, Illinois.,Department of Pharmacology and Regenerative Medicine, University of Illinois College of Medicine, Chicago, Illinois
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Ferrarini I, Rigo A, Montresor A, Laudanna C, Vinante F. Monocyte-to-macrophage switch reversibly impaired by Ibrutinib. Oncotarget 2019; 10:1943-1956. [PMID: 30956776 PMCID: PMC6443008 DOI: 10.18632/oncotarget.26744] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 02/19/2019] [Indexed: 12/14/2022] Open
Abstract
Ibrutinib is increasingly adopted for treating lymphoid malignancies. While growing amounts of data pile up about Ibrutinib mechanism of action on neoplastic B cells, little is known about its impact on other immune cells. Here we investigated the effect of Ibrutinib on monocyte/macrophage functions. (1) Ibrutinib treatment of purified human monocytes affected both chemoattractant-triggered inside-out as well as integrin-mediated outside-in signaling events, thus provoking defective adhesion and spreading on purified integrin ligands, respectively. (2) In in vitro cell-culture experiments, Ibrutinib promoted a differentiation shift of monocytes to fibrocyte-like cells, characterized by the acquisition of a typical elongated cell morphology. Importantly, this clear-cut shape transition also occurred upon culturing monocytes with sera derived from Ibrutinib-treated patients, thus clearly suggesting that the drug concentrations achievable in vivo can generate the phenotypic shift. (3) Ibrutinib-induced fibrocyte-like cells showed adhesion deficiency, altered phagocytic properties, and, with respect to macrophages, they acquired the capability of generating larger amounts of reactive oxygen species, possibly displaying different metabolic activities. Taken together, our results indicate that Ibrutinib has profound effects on the monocyte/macrophage immunobiology. They may finally shed some light about the biological ground of several Ibrutinib-related toxicities.
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Affiliation(s)
- Isacco Ferrarini
- Department of Medicine, University of Verona, Verona, Italy.,Section of Hematology, Cancer Research & Cell Biology Laboratory, University of Verona, Verona, Italy
| | - Antonella Rigo
- Department of Medicine, University of Verona, Verona, Italy.,Section of Hematology, Cancer Research & Cell Biology Laboratory, University of Verona, Verona, Italy
| | - Alessio Montresor
- Department of Medicine, University of Verona, Verona, Italy.,Division of General Pathology, University of Verona, Verona, Italy
| | - Carlo Laudanna
- Department of Medicine, University of Verona, Verona, Italy.,Division of General Pathology, University of Verona, Verona, Italy
| | - Fabrizio Vinante
- Department of Medicine, University of Verona, Verona, Italy.,Section of Hematology, Cancer Research & Cell Biology Laboratory, University of Verona, Verona, Italy
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Liu Y, Zhao J, Zhao Y, Zong S, Tian Y, Chen S, Li M, Liu H, Zhang Q, Jing X, Sun B, Wang H, Sun T, Yang C. Therapeutic effects of lentinan on inflammatory bowel disease and colitis-associated cancer. J Cell Mol Med 2019; 23:750-760. [PMID: 30472806 PMCID: PMC6349230 DOI: 10.1111/jcmm.13897] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/14/2018] [Indexed: 01/03/2023] Open
Abstract
In this study, we investigated the therapeutic potential of lentinan in mouse models of inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). Lentinan decreased the disease activity index and macroscopic and microscopic colon tissue damage in dextran sulphate sodium (DSS)-induced or TNBS-induced models of colitis. High-dose lentinan was more effective than salicylazosulfapyridine in the mouse models of colitis. Lentinan decreased the number of tumours, inflammatory cell infiltration, atypical hyperplasia and nuclear atypia in azoxymethane/DSS-induced CAC model. It also decreased the expression of pro-inflammatory cytokines, such as IL-13 and CD30L, in IBD and CAC model mice possibly by inhibiting Toll-like receptor 4 (TLR4)/NF-κB signalling and the expression of colon cancer markers, such as carcinoembryonic antigen, cytokeratin 8, CK18 and p53, in CAC model mice. In addition, lentinan restored the intestinal bacterial microbiotal community structure in IBD model mice. Thus, it shows therapeutic potential in IBD and CAC model mice possibly by inhibiting TLR4/NF-κB signalling-mediated inflammatory responses and disruption of the intestinal microbiotal structure.
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Affiliation(s)
- Yanrong Liu
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina,Drug Safety Evaluation CenterTianjin International Joint Academy of BiomedicineTianjinChina
| | - Jianmin Zhao
- Department of PathologyHospital of Shun Yi DistrictBeijingChina
| | - Yali Zhao
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina,State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Shumin Zong
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina,State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Yixuan Tian
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina,State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Shuang Chen
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina
| | - Meng Li
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina,State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Huijuan Liu
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina
| | - Qiang Zhang
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina,State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Xueshuang Jing
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina
| | - Bo Sun
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina
| | - Hongzhi Wang
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina,State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Tao Sun
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina,State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Cheng Yang
- Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina,State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
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Synergistic effect of Dermatophagoides pteronyssinus allergen and Escherichia coli lipopolysaccharide on human blood cells. PLoS One 2018; 13:e0207311. [PMID: 30412632 PMCID: PMC6226202 DOI: 10.1371/journal.pone.0207311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/29/2018] [Indexed: 12/31/2022] Open
Abstract
Purpose House dust mites Dermatophagoides pteronyssinus are the main source of major inhalatory allergens inducing inflammatory response. Mite extract contain both allergenic proteins and lipopolysaccharides (LPS). The main allergenic protein, Der p 2, is a functional homolog of sMD-2, a protein providing blood cell response on LPS. Der p 2 may restore the response to LPS in absence of MD-2, but its interaction with LPS in whole blood is unknown. We studied the effect of Der p 2 on LPS-mediated activation of human whole blood cells. Methods Interaction of Der p 2 and LPS was studied on eight healthy donors. The whole blood was incubated with extract of house dust mite Dermatophagoides pteronyssinus (DP-e), recombinant antigenic protein Der p 2 variant 5 (rDep 2), Escherichia coli lipopolysaccharide and their combination. Supernatants were collected for ELISA analysis of protein content. Activation degree was determined by change in concentration of TNF-α, IL-8, IL-1Ra cytokines and sMD-2 protein. Results extract of mite Dermatophagoides pteronyssinus (DP-e) possessed weak inherent activity and did not cause significant increase of cytokine production. Simultaneous activation of blood cells by LPS and DP-e led to considerable increase of pro-inflammatory cytokine production. We have shown the intrinsic inducing activity of Der p 2 allergen on sMD-2 protein and TNF-α cytokine expression. Conclusions Der p 2 allergen enhances the response of human whole blood cells to external LPS by inducing additional expression of LPS-transporting protein sMD-2. The obtained data show an important role of LPS contamination of allegrens in the progress of allergic inflammatory response.
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Fetal and Maternal Innate Immunity Receptors Have Opposing Effects on the Severity of Experimental Malaria in Pregnancy: Beneficial Roles for Fetus-Derived Toll-Like Receptor 4 and Type I Interferon Receptor 1. Infect Immun 2018; 86:IAI.00708-17. [PMID: 29440369 PMCID: PMC5913849 DOI: 10.1128/iai.00708-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 02/07/2018] [Indexed: 12/13/2022] Open
Abstract
Malaria in pregnancy (MiP) is a distinctive clinical form of Plasmodium infection and is a cause of placental insufficiency leading to poor pregnancy outcomes. Maternal innate immunity responses play a decisive role in the development of placental inflammation, but the action of fetus-derived factors in MiP outcomes has been overlooked. We investigated the role of the Tlr4 and Ifnar1 genes, taking advantage of heterogenic mating strategies to dissect the effects mediated by maternally and fetally derived Toll-like receptor 4 (TLR4) or type I interferon receptor 1 (IFNAR1). Using a mouse infection system displaying severe MiP outcomes, we found that the expressions of TLR4 and IFNAR1 in the maternal compartment take part in deleterious MiP outcomes, but their fetal counterparts patently counteract these effects. We uncovered that fetal TLR4 contributes to the in vitro uptake of infected erythrocytes by trophoblasts and to the innate immune response in the placenta, offering robust protection of fetus viability, but had no sensible impact on the placental parasite burden. In contrast, we observed that the expression of IFNAR1 in the fetal compartment was associated with a reduced placental parasite burden but had little beneficial effect on fetus outcomes. Furthermore, the downregulation of Ifnar1 expression in infected placentas and in trophoblasts exposed to infected erythrocytes indicated that the interferon-IFNAR1 pathway is involved in the trophoblast response to infection. This work unravels that maternal and fetal counterparts of innate immune pathways drive opposing responses in murine placental malaria and implicates the activation of innate receptors in fetal trophoblast cells in the control of placental infection and in the protection of the fetus.
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Toll-Like Receptor 4 Reduces Oxidative Injury via Glutathione Activity in Sheep. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2016:9151290. [PMID: 26640618 PMCID: PMC4657145 DOI: 10.1155/2016/9151290] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/28/2015] [Indexed: 01/07/2023]
Abstract
Toll-like receptor 4 (TLR4) is an important sensor of Gram-negative bacteria and can trigger activation of the innate immune system. Increased activation of TLR4 can lead to the induction of oxidative stress. Herein, the pathway whereby TLR4 affects antioxidant activity was studied. In TLR4-overexpressing sheep, TLR4 expression was found to be related to the integration copy number when monocytes were challenged with lipopolysaccharide (LPS). Consequently, production of malondialdehyde (MDA) was increased, which could increase the activation of prooxidative stress enzymes. Meanwhile, activation of an antioxidative enzyme, glutathione peroxidase (GSH-Px), was increased. Real-time PCR showed that expression of activating protein-1 (AP-1) and the antioxidative-related genes was increased. By contrast, the expression levels of superoxide dismutase 1 (SOD1) and catalase (CAT) were reduced. In transgenic sheep, glutathione (GSH) levels were dramatically reduced. Furthermore, transgenic sheep were intradermally injected with LPS in each ear. The amounts of inflammatory infiltrates were correlated with the number of TLR4 copies that were integrated in the genome. Additionally, the translation of γ-glutamylcysteine synthetase (γ-GCS) was increased. Our findings indicated that overexpression of TLR4 in sheep could ameliorate oxidative injury through GSH secretion that was induced by LPS stimulation. Furthermore, TLR4 promoted γ-GCS translation through the AP-1 pathway, which was essential for GSH synthesis.
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Kagan JC, Barton GM. Emerging principles governing signal transduction by pattern-recognition receptors. Cold Spring Harb Perspect Biol 2014; 7:a016253. [PMID: 25395297 PMCID: PMC4355268 DOI: 10.1101/cshperspect.a016253] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The problem of recognizing and disposing of non-self-organisms, whether for nutrients or defense, predates the evolution of multicellularity. Accordingly, the function of the innate immune system is often intimately associated with fundamental aspects of cell biology. Here, we review our current understanding of the links between cell biology and pattern-recognition receptors of the innate immune system. We highlight the importance of receptor localization for the detection of microbes and for the initiation of antimicrobial signaling pathways. We discuss examples that illustrate how pattern-recognition receptors influence, and are influenced by, the general membrane trafficking machinery of mammalian cells. In the future, cell biological analysis likely will rival pure genetic analysis as a tool to uncover fundamental principles that govern host-microbe interactions.
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Affiliation(s)
- Jonathan C Kagan
- Harvard Medical School and Division of Gastroenterology, Boston Children's Hospital, Boston, Massachusetts 02115
| | - Gregory M Barton
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, California 94720-3200
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Meana C, Peña L, Lordén G, Esquinas E, Guijas C, Valdearcos M, Balsinde J, Balboa MA. Lipin-1 integrates lipid synthesis with proinflammatory responses during TLR activation in macrophages. THE JOURNAL OF IMMUNOLOGY 2014; 193:4614-22. [PMID: 25252959 DOI: 10.4049/jimmunol.1400238] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Lipin-1 is a Mg(2+)-dependent phosphatidic acid phosphatase involved in the de novo synthesis of phospholipids and triglycerides. Using macrophages from lipin-1-deficient animals and human macrophages deficient in the enzyme, we show in this work that this phosphatase acts as a proinflammatory mediator during TLR signaling and during the development of in vivo inflammatory processes. After TLR4 stimulation lipin-1-deficient macrophages showed a decreased production of diacylglycerol and activation of MAPKs and AP-1. Consequently, the generation of proinflammatory cytokines like IL-6, IL-12, IL-23, or enzymes like inducible NO synthase and cyclooxygenase 2, was reduced. In addition, animals lacking lipin-1 had a faster recovery from endotoxin administration concomitant with a reduced production of harmful molecules in spleen and liver. These findings demonstrate an unanticipated role for lipin-1 as a mediator of macrophage proinflammatory activation and support a critical link between lipid biosynthesis and systemic inflammatory responses.
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Affiliation(s)
- Clara Meana
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain; and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
| | - Lucía Peña
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain; and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
| | - Gema Lordén
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain; and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
| | - Esperanza Esquinas
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain; and
| | - Carlos Guijas
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain; and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
| | - Martín Valdearcos
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain; and
| | - Jesús Balsinde
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain; and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
| | - María A Balboa
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain; and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
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11
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van Lieshout MHP, van der Poll T, van't Veer C. TLR4 inhibition impairs bacterial clearance in a therapeutic setting in murine abdominal sepsis. Inflamm Res 2014; 63:927-33. [PMID: 25118783 DOI: 10.1007/s00011-014-0766-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 06/25/2014] [Accepted: 07/29/2014] [Indexed: 01/07/2023] Open
Abstract
OBJECTIVE AND DESIGN To investigate the therapeutic effect of E5564 (a clinically used TLR4 inhibitor) in murine abdominal sepsis elicited by intraperitoneal infection with a highly virulent Escherichia coli in the context of concurrent antibiotic therapy. METHODS Mice were infected with different doses (~2 × 10(4)-2 × 10(6) CFU) of E. coli O18:K1 and treated after 8 h with ceftriaxone 20 mg/kg i.p. combined with either E5564 10 mg/kg i.v. or vehicle. For survival studies this treatment was repeated every 12 h. Bacterial loads and inflammatory parameters were determined after 20 h in peritoneal lavage fluid, blood, liver and lung tissue. Plasma creatinin, AST, ALT and LDH were determined to assess organ injury. RESULTS E5564 impaired bacterial clearance under the antibiotic regime after infection with a low dose E. coli (1.7 × 10(4) CFU) while renal function was slightly preserved. No differences were observed in bacterial load and organ damage after infection with a tenfold higher (1.7 × 10(5) E. coli) bacterial dose. While treatment with E5564 slightly attenuated inflammatory markers provoked by the sublethal doses of 104-105 E. coli under the antibiotic regime, it did not affect lethality evoked by infection with 1.7 × 106 E. coli. CONCLUSIONS The impact of TLR4 inhibition during abdominal sepsis by virulent E. coli bacteria is only beneficial at low infection grade at cost of bactericidal activity.
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Affiliation(s)
- Miriam H P van Lieshout
- Center of Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands,
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12
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Awasthi S. Toll-like receptor-4 modulation for cancer immunotherapy. Front Immunol 2014; 5:328. [PMID: 25120541 PMCID: PMC4110442 DOI: 10.3389/fimmu.2014.00328] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 06/27/2014] [Indexed: 12/13/2022] Open
Affiliation(s)
- Shanjana Awasthi
- Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center , Oklahoma City, OK , USA
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13
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Nagai Y, Watanabe Y, Takatsu K. The TLR family protein RP105/MD-1 complex: A new player in obesity and adipose tissue inflammation. Adipocyte 2013; 2:61-6. [PMID: 23805400 PMCID: PMC3661108 DOI: 10.4161/adip.22929] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 11/14/2012] [Accepted: 11/16/2012] [Indexed: 12/20/2022] Open
Abstract
The radioprotective 105 (RP105)/MD-1 complex is a member of the Toll-like receptor (TLR) family of proteins. We have previously reported that this complex cooperates with the essential lipopolysaccharide (LPS) receptor TLR4/MD-2 complex and plays a crucial role in LPS responses by B cells. Recent evidences suggest that TLRs can also recognize endogenous ligands and promote non-infectious chronic inflammation. For instance, TLR4/MD-2 can be ligated by adipose tissue-derived saturated free fatty acids (FAs) and induce adipose tissue inflammation and insulin resistance. Recently, we reported that RP105 knockout (KO) or MD-1 KO mice have less high-fat diet (HFD)-induced obesity, adipose tissue inflammation and insulin resistance than wild-type (WT) or TLR4 KO mice. As RP105/MD-1 is not involved in recognition of palmitic and stearic acids, which are endogenous ligands for TLR4/MD-2, we conclude that RP105/MD-1 is itself a key regulator of diet-induced chronic inflammation in adipose tissue, obesity and insulin resistance that appears to be independent of the TLR4-dependent pathway. In this mini-review, we will highlight the significance of the RP105/MD-1 complex in adipose tissue inflammation and discuss implications for human diseases.
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14
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Dunn-Siegrist I, Tissières P, Drifte G, Bauer J, Moutel S, Pugin J. Toll-like receptor activation of human cells by synthetic triacylated lipid A-like molecules. J Biol Chem 2012; 287:16121-31. [PMID: 22433865 DOI: 10.1074/jbc.m112.348383] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Recognition of microbial molecules by mammalian host receptors is essential to mount an immune response. Hexaacylated LPS is the prototypic example of a bacterial molecule recognized by the receptor complex TLR4/MD-2 with its lipid A moiety, whereas bacterial lipopeptides are recognized by TLR2. Here we show that a series of synthetic triacylated lipid A-like molecules are weak Toll-like receptor (TLR) agonists (mainly TLR2 agonists) but very potent TLR4/MD-2 antagonists (submicromolar range). Not only do they block human cell responses to LPS but also to whole gram-negative bacteria, and they inhibit the phagocytosis of gram-negative bacteria. These compounds may represent promising immunomodulatory agents.
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Affiliation(s)
- Irène Dunn-Siegrist
- Intensive Care Laboratory and Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, 1211 Geneva 14, Switzerland
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15
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Sasaki S, Nagai Y, Yanagibashi T, Watanabe Y, Ikutani M, Kariyone A, Tsuneyama K, Hirai Y, Takatsu K. Serum soluble MD-1 levels increase with disease progression in autoimmune prone MRL(lpr/lpr) mice. Mol Immunol 2011; 49:611-20. [PMID: 22118968 DOI: 10.1016/j.molimm.2011.10.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 10/04/2011] [Accepted: 10/26/2011] [Indexed: 10/15/2022]
Abstract
MD-1 is a secreted protein that forms a complex with radioprotective 105 (RP105) and this complex plays a crucial role in lipopolysaccharide (LPS) recognition by B cells. Disease progression is known to improve in RP105-deficient lupus-prone MRL(lpr/lpr) mice. Furthermore, a soluble form of the homologous MD-2 protein is present in the plasma of septic patients and can opsonize gram-negative bacteria in cooperation with Toll-like receptor (TLR) 4. We have now established a flow cytometry-based assay to detect the soluble form of murine MD-1 (sMD-1) and explored potential roles in autoimmunity. The assay was quantitative and validated with sera from MD-1-deficient mice. Interestingly, heat-inactivated murine serum diminished the ability of sMD-1 to bind RP105. The sMD-1 was secreted by bone marrow-derived macrophages from C57BL/6 mice. Autoimmune prone MRL(lpr/lpr) mice had higher levels of sMD-1 than control MRL(+/+) mice, and levels markedly increased with disease progression. Expression of MD-1 but not MD-2 mRNA increased with age in the liver and kidney of MRL(lpr/lpr) mice. Finally, immunohistochemical analyses revealed that MD-1 was present in infiltrated macrophages within perivascular lesions of the MRL(lpr/lpr) kidney. This correlation suggests that sMD-1 may contribute to pathogenesis in this autoimmune disease model.
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Affiliation(s)
- Sumiyo Sasaki
- Department of Immunobiology and Pharmacological Genetics, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, 2630 Sugitani, Toyama-shi, Toyama 930-0194, Japan
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16
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Shibata T, Motoi Y, Tanimura N, Yamakawa N, Akashi-Takamura S, Miyake K. Intracellular TLR4/MD-2 in macrophages senses Gram-negative bacteria and induces a unique set of LPS-dependent genes. Int Immunol 2011; 23:503-10. [PMID: 21712422 DOI: 10.1093/intimm/dxr044] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Toll-like receptor (TLR)4/MD-2, a sensor for LPS, delivers the MyD88-dependent signal from the cell surface, then traffics to endolysosomes and delivers the TRIF/TICAM-1-dependent signal. Both signals are thought to be dependent on cell surface TLR4/MD-2. Although TLR4/MD-2 is located also in recycling endosomes, the Golgi apparatus or the endoplasmic reticulum, little is known about a role for intracellular TLR4/MD-2 in LPS responses. We here studied intracellular LPS sensing in macrophages. PRAT4A (protein associated with TLR4 A) is a cochaperone for a general chaperone gp96 and required for cell surface expression of TLR4/MD-2. Cell surface TLR4/MD-2 was undetectable on PRAT4A(-/-) thioglycollate-elicited peritoneal macrophages (P-Macs) and bone marrow-derived macrophages (BM-Macs). LPS responses were all abolished in PRAT4A(-/-) P-Macs, whereas a part of LPS responses remained detectable in PRAT4A(-/-) BM-Macs. Of note, LPS responses in PRAT4A(-/-) BM-Macs were not necessarily dependent on TRIF/TICAM-1 signaling. PRAT4A(-/-) BM-Macs showed unimpaired production of both TRIF/TICAM-1-dependent chemokine RANTES (CCL5) and MyD88-dependent chemokine MCP-1 (CCL2). Moreover, up-regulation of co-stimulatory molecules, CD40 and CD86 was not altered. In contrast, TRIF/TICAM-1-dependent production of type I IFN was profoundly impaired. In response to heat-killed bacteria Escherichia coli, BM-Macs also required PRAT4A-independent TLR4/MD-2 for production of MCP-1 (CCL2) and RANTES (CCL5) and for up-regulation of CD40 and CD86, indicating that intracellular TLR4/MD-2 is able to sense phagocytosed bacteria and activate immune responses. These results demonstrate that intracellular TLR4/MD-2 is responsible for unique set of LPS responses.
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Affiliation(s)
- Takuma Shibata
- Division of Infectious Genetics, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minatoku, Tokyo 108-8639, Japan
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17
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Oz HS, Ebersole JL, de Villiers WJS. The macrophage pattern recognition scavenger receptors SR-A and CD36 protect against microbial induced pregnancy loss. Inflamm Res 2011; 60:93-7. [PMID: 20711846 PMCID: PMC4129389 DOI: 10.1007/s00011-010-0241-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 08/02/2010] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVES AND DESIGN Microbial products can act via stress-induced signaling cascades to link dysregulated endogenous microbiota to immune activation (e.g., macrophages) and pregnancy loss. Our previous studies demonstrated that mice deficient in the macrophage pattern recognition scavenger receptors, SR-A and CD36, are more susceptible to inflammatory complications including gut leakiness and experimental colitis. We hypothesized that bacterial penetration of the maternal mucosal surfaces and replication in embryonic fluids compromise the fetal status and can result in miscarriage. MATERIALS AND METHODS Eighty pregnant ICR and SR-A/CD36-deficient mice were injected via tail vein or intraperitoneally with commensal bacteria (Streptococcus cricetus and/or Actinobacillus sp.) or sham controls. Dams were monitored daily for physical distress, pain and abortion. RESULTS Dams injected with single dose bacterial inoculum did not develop clinical symptoms. Day old pups injected with bacteria developed internal focal abscesses, lost weight but recovered after 1 week. Dams receiving a second bacterial inoculum delivered dead fetuses. However, SR-A/CD36-deficnet dams demonstrated 100% fetal death via aborted fetuses, and significant up-regulation of the proinflammatory markers (IL-6, serum Amyloid A) 24-74 h after single inoculum. CONCLUSIONS These data indicate that macrophage scavenger receptors are required for the fetal protection against microbial attack and support that maternal transfer of innate immunity contributes to this protection.
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Affiliation(s)
- Helieh S Oz
- Center for Oral Health Research, MN310 College of Dentistry and Internal Medicine, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA.
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18
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Awasthi S, Brown K, King C, Awasthi V, Bondugula R. A toll-like receptor-4-interacting surfactant protein-A-derived peptide suppresses tumor necrosis factor-α release from mouse JAWS II dendritic cells. J Pharmacol Exp Ther 2010; 336:672-81. [PMID: 21159752 DOI: 10.1124/jpet.110.173765] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Surfactant protein-A (SP-A) and Toll-like receptor-4 (TLR4) proteins are recognized as pathogen-recognition receptors. An exaggerated activation of TLR4 induces inflammatory response, whereas SP-A protein down-regulates inflammation. We hypothesized that SP-A-TLR4 interaction may lead to inhibition of inflammation. In this study, we investigated interaction between native baboon lung SP-A and baboon and human TLR4-MD2 proteins by coimmunoprecipitation/immunoblotting and microwell-based methods. The interaction between SP-A and TLR4-MD2 proteins was then analyzed using a bioinformatics approach. In the in silico model of SP-A-TLR4-MD2 complex, we identified potential binding regions and amino acids at the interface of SP-A-TLR4. Using this information, we synthesized a library of human SP-A-derived peptides that contained interacting amino acids. Next, we tested whether the TLR4-interacting SP-A peptides would suppress inflammatory cytokines. The peptides were screened for any changes in the tumor necrosis factor-α (TNF-α) response against lipopolysaccharide (LPS) stimuli in the mouse JAWS II dendritic cell line. Different approaches used in this study suggested binding between SP-A and TLR4-MD2 proteins. In cells pretreated with peptides, three of seven peptides increased TNF-α production against LPS. However, two of these peptides (SPA4: GDFRYSDGTPVNYTNWYRGE and SPA5: YVGLTEGPSPGDFRYSDFTP) decreased the TNF-α production in LPS-challenged JAWS II dendritic cells; SPA4 peptide showed more pronounced inhibitory effect than SPA5 peptide. In conclusion, we identify a human SP-A-derived peptide (SPA4 peptide) that interacts with TLR4-MD2 protein and inhibits the LPS-stimulated release of TNF-α in JAWS II dendritic cells.
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Affiliation(s)
- Shanjana Awasthi
- Department of Pharmaceutical Sciences, University of Oklahoma Health Science Center, Oklahoma City, OK, USA.
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19
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Husebye H, Aune MH, Stenvik J, Samstad E, Skjeldal F, Halaas Ø, Nilsen NJ, Stenmark H, Latz E, Lien E, Mollnes TE, Bakke O, Espevik T. The Rab11a GTPase controls Toll-like receptor 4-induced activation of interferon regulatory factor-3 on phagosomes. Immunity 2010; 33:583-96. [PMID: 20933442 PMCID: PMC10733841 DOI: 10.1016/j.immuni.2010.09.010] [Citation(s) in RCA: 158] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 06/22/2010] [Accepted: 09/15/2010] [Indexed: 02/06/2023]
Abstract
Toll-like receptor 4 (TLR4) is indispensable for recognition of Gram-negative bacteria. We described a trafficking pathway for TLR4 from the endocytic recycling compartment (ERC) to E. coli phagosomes. We found a prominent colocalization between TLR4 and the small GTPase Rab11a in the ERC, and Rab11a was involved in the recruitment of TLR4 to phagosomes in a process requiring TLR4 signaling. Also, Toll-receptor-associated molecule (TRAM) and interferon regulatory factor-3 (IRF3) localized to E. coli phagosomes and internalization of E. coli was required for a robust interferon-β induction. Suppression of Rab11a reduced TLR4 in the ERC and on phagosomes leading to inhibition of the IRF3 signaling pathway induced by E. coli, whereas activation of the transcription factor NF-κB was unaffected. Moreover, Rab11a silencing reduced the amount of TRAM on phagosomes. Thus, Rab11a is an important regulator of TLR4 and TRAM transport to E. coli phagosomes thereby controlling IRF3 activation from this compartment.
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Affiliation(s)
- Harald Husebye
- Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, N-7489 Trondheim, Norway
- These authors contributed equally to this work
| | - Marie Hjelmseth Aune
- Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, N-7489 Trondheim, Norway
- These authors contributed equally to this work
| | - Jørgen Stenvik
- Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, N-7489 Trondheim, Norway
- These authors contributed equally to this work
| | - Eivind Samstad
- Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, N-7489 Trondheim, Norway
| | - Frode Skjeldal
- Department of Molecular Biosciences, Centre for Immune Regulation, University of Oslo, N-0316 Oslo, Norway
| | - Øyvind Halaas
- Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, N-7489 Trondheim, Norway
| | - Nadra J. Nilsen
- Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, N-7489 Trondheim, Norway
| | - Harald Stenmark
- Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, N-7489 Trondheim, Norway
- Department of Biochemistry, Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, N-0310 Oslo, Norway
| | - Eicke Latz
- Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, N-7489 Trondheim, Norway
- Institute of Innate Immunity, Biomedical Center, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany
| | - Egil Lien
- Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, N-7489 Trondheim, Norway
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Tom Eirik Mollnes
- Institute of Immunology, Rikshospitalet University Hospital, University of Oslo, N-0027 Oslo, Norway
| | - Oddmund Bakke
- Department of Molecular Biosciences, Centre for Immune Regulation, University of Oslo, N-0316 Oslo, Norway
- The Gade Institute, University of Bergen, 5021 Bergen, Norway
| | - Terje Espevik
- Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, N-7489 Trondheim, Norway
- St. Olavs Hospital, N-7489 Trondheim, Norway
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20
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Hedayat M, Takeda K, Rezaei N. Prophylactic and therapeutic implications of toll-like receptor ligands. Med Res Rev 2010; 32:294-325. [DOI: 10.1002/med.20214] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Mona Hedayat
- Molecular Immunology Research Center; Department of Immunology; School of Medicine; Tehran University of Medical Sciences; Tehran; Iran
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21
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Coffey TJ, Werling D. Therapeutic targeting of the innate immune system in domestic animals. Cell Tissue Res 2010; 343:251-61. [DOI: 10.1007/s00441-010-1054-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 09/08/2010] [Indexed: 12/23/2022]
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Crystal structure of soluble MD-1 and its interaction with lipid IVa. Proc Natl Acad Sci U S A 2010; 107:10990-5. [PMID: 20534476 DOI: 10.1073/pnas.1004153107] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Lipopolysaccharide (LPS) of Gram-negative bacteria is a common pathogen-associated molecular pattern (PAMP) that induces potent innate immune responses. The host immune response against LPS is triggered by myeloid differentiation factor 2 (MD-2) in association with Toll-like receptor 4 (TLR4) on the cell surface. The MD-2/TLR4-mediated LPS response is regulated by the evolutionarily related complex of MD-1 and Toll-like receptor homolog RP105. Here, we report crystallographic and biophysical data that demonstrate a previously unidentified direct interaction of MD-1 with LPS. The crystal structure of chicken MD-1 (cMD-1) at 2.0 A resolution exhibits a beta-cup-like fold, similar to MD-2, that encloses a hydrophobic cavity between the two beta-sheets. A lipid-like moiety was observed inside the cavity, suggesting the possibility of a direct MD-1/LPS interaction. LPS was subsequently identified as an MD-1 ligand by native gel electrophoresis and gel filtration analyses. The crystal structure of cMD-1 with lipid IVa, an LPS precursor, at 2.4 A resolution revealed that the lipid inserts into the deep hydrophobic cavity of the beta-cup-like structure, but with some important differences compared with MD-2. These findings suggest that soluble MD-1 alone, in addition to its complex with RP105, can regulate host LPS sensitivity.
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Ohnishi T, Muroi M, Tanamoto KI. Inhibitory effects of soluble MD-2 and soluble CD14 on bacterial growth. Microbiol Immunol 2010; 54:74-80. [PMID: 20377740 DOI: 10.1111/j.1348-0421.2009.00186.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The effects of the soluble forms of the endotoxin receptor molecules sMD-2 and sCD14 on bacterial growth were studied. When Escherichia coli and Bacillus subtilis were incubated at 37 degrees C for 18 hr with either sMD-2 or sCD14, growth of these bacteria was significantly inhibited as evaluated by viable cell counts and NADPH/NADH activity. A mutant of sCD14 (sCD14d57-64) lacking a region essential for LPS binding did not inhibit the growth of E. coli, whereas this mutant did inhibit the growth of B. subtilis. Addition of excess PG to the bacterial culture reversed the inhibitory effect of sMD-2 on the growth of B. subtilis, but not on the growth of E. coli. Furthermore, when evaluated by ELISA, both sMD-2 and sCD14 bound specifically to PG. Taken together, these results indicate that sMD-2 and sCD14 inhibit the growth of both Gram-positive and Gram-negative bacteria and further suggest that binding to PG and LPS is involved in the inhibitory effect of sMD-2 on Gram-positive bacteria and of sCD14 on Gram-negative bacteria, respectively.
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Affiliation(s)
- Takahiro Ohnishi
- Division of Microbiology, National Institute of Health Sciences, Setagaya, Tokyo 158-8501, Japan.
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24
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Wolfs TGAM, Derikx JPM, Hodin CMIM, Vanderlocht J, Driessen A, de Bruïne AP, Bevins CL, Lasitschka F, Gassler N, van Gemert WG, Buurman WA. Localization of the lipopolysaccharide recognition complex in the human healthy and inflamed premature and adult gut. Inflamm Bowel Dis 2010; 16:68-75. [PMID: 20014022 DOI: 10.1002/ibd.20995] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Microbiota in the intestinal lumen provide an abundant source of potentially detrimental antigens, including lipopolysaccharide (LPS), a potent immunostimulatory product of Gram-negative bacteria recognized by the host via TLR-4 and MD-2. An aberrant immune response to LPS or other bacterial antigens has been linked to inflammatory bowel disease (IBD) and necrotizing enterocolitis (NEC). METHODS We investigated which cells express MD-2 in the normal and inflamed ileum from neonates and adults by immunohistochemistry. Moreover, MD-2 and TLR4 mRNA expression in normal adult ileum was studied by reverse-transcription polymerase chain reaction (RT-PCR) on cells isolated by laser capture microdissection. RESULTS Premature infants did not show MD-2 expression either in epithelial cells or in the lamina propria. Similarly, MD-2 was absent in epithelial cells and lamina propria inflammatory cells in preterm infants with NEC. MD-2 protein in the healthy term neonatal and adult ileum was predominantly expressed by Paneth cells and some resident inflammatory cells in the lamina propria. MD-2 and TLR-4 mRNA expression was restricted to crypt cells. Also in IBD, Paneth cells were still the sole MD-2-expressing epithelial cells, whereas inflammatory cells (mainly plasma cells) were responsible for the vast majority of the MD-2 expression. CONCLUSIONS The absence of MD-2 in the immature neonatal gut suggests impaired LPS sensing, which could predispose neonates to NEC upon microbial colonization of the immature intestine. The apparent expression of MD-2 by Paneth cells supports the critical concept that these cells respond to luminal bacterial products in order to maintain homeostasis with the intestinal microbiota in vivo.
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Affiliation(s)
- Tim G A M Wolfs
- Department of Surgery, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University Medical Centre, Maastricht, the Netherlands
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25
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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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26
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Tissières P, Araud T, Ochoda A, Drifte G, Dunn-Siegrist I, Pugin J. Cooperation between PU.1 and CAAT/enhancer-binding protein beta is necessary to induce the expression of the MD-2 gene. J Biol Chem 2009; 284:26261-72. [PMID: 19632992 DOI: 10.1074/jbc.m109.042580] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Myeloid differentiation factor 2 (MD-2) binds Gram-negative bacterial lipopolysaccharide with high affinity and is essential for Toll-like receptor 4-dependent signal transduction. MD-2 has recently been recognized as a type II acute phase protein. Plasma concentrations of the soluble form of MD-2 increase markedly during the course of severe infections. Its production is regulated in hepatocytes and myeloid cells by interleukin-6 (IL-6) but not IL-1beta. In the present work we show that two transcription factors (TF), PU.1 and CAAT/enhancer-binding protein beta (C/EBPbeta), participate in the activation of the human MD-2 gene in hepatocytic cells after stimulation with IL-6. PU.1 TF and proximal PU.1 binding sites in the MD-2 promoter were shown to be critical for the basal activity of the promoter as well as for IL-6-induced soluble MD-2 production. Deletions of proximal portions of the MD-2 promoter containing PU.1 and/or NF-IL-6 consensus binding sites as well as site-directed mutagenesis of these binding sites abrogated IL-6-dependent MD-2 gene activation. We show that the cooperation between C/EBPbeta and PU.1 is critical for the transcriptional activation of the MD-2 gene by IL-6. PU.1 was essentially known as a TF involved in the differentiation of myeloid precursor cells and the expression of surface receptors of the innate immunity. Herein, we show that it also participates in the regulation of an acute phase protein, MD-2, in nonmyeloid cells cooperatively with C/EBPbeta, a classical IL-6-inducible TF.
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Affiliation(s)
- Pierre Tissières
- Intensive Care, University Hospitals of Geneva, Geneva 14, Switzerland
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Oz HS, Chen TS, Neuman M. Nutrition intervention: a strategy against systemic inflammatory syndrome. JPEN J Parenter Enteral Nutr 2009; 33:380-9. [PMID: 19380752 PMCID: PMC3063840 DOI: 10.1177/0148607108327194] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Sepsis and septic shock syndrome are the leading causes of death in critically ill patients. Lipopolysaccharide (LPS) released by the colonic microorganisms may translocate across a compromised lumen, leading to upregulated reactive oxidative stress, inflammation, and sepsis. The authors examined an enteral formula high in cysteine (antioxidant precursor), omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and prebiotic fructooligosaccharides (FOS) against systemic inflammatory syndrome. METHODS Rats were allocated to (1) standard soy-based diet high in cysteine and crude fiber and devoid of EPA-DHA (CHOW); (2) whey-peptide-based liquid diet high in cysteine, EPA-DHA, and FOS (CYSPUFA); or (3) casein-based liquid isonitrogenous diet, low in cysteine and devoid of EPA-DHA-FOS (CASN). Liquid diets provided 25% and CHOW, 23% of calories as protein. After 6 days on diets, rats received an intraperitoneal injection of LPS or saline. Animals gained weight on their respective diets and lost weight after LPS administration. The CYSPUFA group lost considerably less weight (vs CASN or CHOW, P < .05). Inflammatory cytokines significantly increased by 4 hours and subsided 18 hours after assault. The CASN group showed elevated liver enzyme alanine aminotransferase release from damaged hepatocytes and developed severe hepatic pathology with low hematocrit. The CHOW group developed more severe hepatic lesions compared with those on liquid diets. Concentration of liver enzyme and pathology were improved in rats receiving CYSPUFA. CONCLUSIONS Data indicate that CYSPUFA, a diet rich in EPA-DHA-FOS, protects against LPS-induced systemic inflammatory responses and warrants clinical studies in critically ill patients.
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Affiliation(s)
- Helieh S Oz
- Center for Oral Health Research, University of Kentucky Medical Center, Lexington, Kentucky 40536, USA.
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Abstract
PURPOSE OF REVIEW The identification of human Toll-like receptors has drastically changed our understanding of host-pathogen interactions. This review presents recent data on myeloid differentiation factor 2 (MD-2), a membrane-bound and soluble receptor for Gram-negative lipopolysaccharide, and its central role in the recognition of Gram-negative bacteria, phagocytosis, and Toll-like receptor 4 signalling. RECENT FINDINGS Phagocytosis is a complex mechanism involving a variety of receptors and opsonins. The heterogeneity of phagocytic mechanisms allows the optimization of bacteria recognition, phagocytosis, and killing. Notably, Toll-like receptors were known to play a role in phagocytosis, both by modulating opsonins and phagocytosis receptors' expression and activity, and by contributing to bacterial recognition and presentation to host cells. Recent data provide additional insight into the function of Toll-like receptors and associated proteins. In addition to bacterial recognition and activation of inflammatory cascades, MD-2 has been recently shown to be an opsonin for Gram-negative bacteria and an acute-phase protein. These newly described characteristics directly link Gram-negative bacteria recognition, transduction of Toll-like receptor 4 inflammatory signalling, phagocytosis and bacterial clearance. SUMMARY Recent progress in the understanding of Gram-negative bacteria recognition by host cells as well as physiologic functionality of MD-2 suggests that MD-2 is a critical compound in host response to pathogens and plays a central role in physiologic adaptation to various insults.
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Lipopolysaccharide-trap-Fc, a multifunctional agent to battle gram-negative bacteria. Infect Immun 2009; 77:2925-31. [PMID: 19433546 DOI: 10.1128/iai.00004-09] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The family of Toll-like receptors (TLRs) plays a pivotal role in host defense against pathogens. However, overstimulation of these receptors may lead to uncontrolled general inflammation and eventually to systemic organ dysfunction or failure. With the intent to control overwhelming inflammation during gram-negative bacterial sepsis, we constructed soluble fusion proteins of the lipopolysaccharide (LPS)-receptor complex to modulate TLR signaling in multiple ways. The extracellular domain of mouse TLR4 and mouse myeloid differentiation factor 2 (MD-2) fusions (LPS-Trap) were linked to human immunoglobulin G Fc domains (LPS-Trap-Fc). In addition to the ability to bind LPS or gram-negative bacteria and to inhibit interleukin-6 secretion of monocytic cells after LPS treatment, LPS-Trap-Fc was able to opsonize fluorescent Escherichia coli particles. This led to enhancement of phagocytosis by monocytic cells which was strictly dependent on the presence of the Fc region. Moreover, only LPS-Trap-Fc- and not LPS-Trap-coated bacteria were sensitized to complement killing. Therefore, LPS-Trap-Fc not only neutralizes LPS but also, after binding to bacteria, enhances phagocytosis and complement-mediated killing and could thus act as a multifunctional agent to fight gram-negative bacteria in vivo.
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Sandanger Ø, Ryan L, Bohnhorst J, Iversen AC, Husebye H, Halaas Ø, Landrø L, Aukrust P, Frøland SS, Elson G, Visintin A, Øktedalen O, Damås JK, Sundan A, Golenbock D, Espevik T. IL-10 enhances MD-2 and CD14 expression in monocytes and the proteins are increased and correlated in HIV-infected patients. THE JOURNAL OF IMMUNOLOGY 2009; 182:588-95. [PMID: 19109192 DOI: 10.4049/jimmunol.182.1.588] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Soluble proteins that bind LPS, like myeloid differentiation-2 (MD-2) and CD14, have essential roles in regulating LPS signaling through TLR4. During a gram-negative bacterial infection, the host may control the response by adjusting the levels of soluble MD-2 and CD14. To address the surface expression of MD-2 on human leukocytes, we developed a mAb, IIC1, that recognized MD-2 both free and when bound to TLR4. MD-2 was found on the surface of freshly isolated monocytes, on a subpopulation of CD19(+) B-cells and on CD15(+) neutrophils. LPS transiently reduced the MD-2 levels on monocytes, which is most likely due to endocytosis of the LPS receptor complex since MD-2 colocalized with TLR4 in early endosomes after LPS stimulation. In the absence of LPS, MD-2 partly colocalized with TLR4 in Golgi trans and medial compartments. Cultivating monocytes for 18-20 h resulted in loss of MD-2 expression on the surface, which was reversed either by LPS or IL-10. Furthermore, addition of IL-10, but not LPS, resulted in a considerable increase in mRNA for both MD-2 and CD14. Using ELISA, we demonstrated that IL-10 had a profound dose- and time-related effect on the release of soluble MD-2 and soluble CD14 from monocytes. In HIV-infected patients, the amounts of MD-2, CD14, and IL-10 increased significantly in the patient group with AIDS. Of interest, we found that IL-10, CD14, and MD-2 levels were positively correlated, suggesting that IL-10 may be a driving force for increased release of MD-2 and CD14 during systemic inflammation.
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Affiliation(s)
- Øystein Sandanger
- Norwegian University of Science and Technology, Institute of Cancer Research and Molecular Medicine, Trondheim, Norway
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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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Moulakakis C, Stamme C. Role of clathrin-mediated endocytosis of surfactant protein A by alveolar macrophages in intracellular signaling. Am J Physiol Lung Cell Mol Physiol 2009; 296:L430-41. [PMID: 19136579 DOI: 10.1152/ajplung.90458.2008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We recently provided evidence that anti-inflammatory macrophage activation, i.e., the inhibition of constitutive and signal-induced NF-kappaB activity by the pulmonary collectin surfactant protein (SP)-A, critically involves a promoted stabilization of IkappaB-alpha, the predominant inhibitor of NF-kappaB, via posttranscriptional mechanisms comprising the activation of atypical (a)PKCzeta. SP-A uptake and degradation by alveolar macrophages (AMphi) occur in a receptor-mediated, clathrin-dependent manner. However, a mutual link between endocytosis of and signaling by SP-A remains elusive. The aim of this study was to investigate whether clathrin-mediated endocytosis (CME) of SP-A by AMphi is a prerequisite for its modulation of the IkappaB-alpha/NF-kappaB pathway. The inhibition of clathrin-coated pit (CCP) formation and clathrin-coated vesicle (CCV) formation/budding abrogates SP-A-mediated IkappaB-alpha stabilization and SP-A-mediated inhibition of LPS-induced NF-kappaB activation in freshly isolated rat AMphi, as determined by Western analysis, fluorescence-activated cell sorting, confocal microscopy, and EMSA. Actin depolymerization and inhibition of CCP formation further abolished SP-A-mediated inhibition of LPS-induced TNF-alpha release, as determined by ELISA. In addition, SP-A-induced atypical PKCzeta activation was abolished by pretreatment of AMphi with CCV inhibitors as determined by in vitro immunocomplex kinase assay. Although CME is classically considered as a means to terminate signaling, our results demonstrate that SP-A uptake via CME by AMphi has to precede the initiation of SP-A signaling.
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Affiliation(s)
- Christina Moulakakis
- Department of Clinical Medicine, Division of Cellular Pneumology, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Borstel, Germany
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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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