1
|
Massier L, Musat N, Stumvoll M, Tremaroli V, Chakaroun R, Kovacs P. Tissue-resident bacteria in metabolic diseases: emerging evidence and challenges. Nat Metab 2024; 6:1209-1224. [PMID: 38898236 DOI: 10.1038/s42255-024-01065-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/13/2024] [Indexed: 06/21/2024]
Abstract
Although the impact of the gut microbiome on health and disease is well established, there is controversy regarding the presence of microorganisms such as bacteria and their products in organs and tissues. However, recent contamination-aware findings of tissue-resident microbial signatures provide accumulating evidence in support of bacterial translocation in cardiometabolic disease. The latter provides a distinct paradigm for the link between microbial colonizers of mucosal surfaces and host metabolism. In this Perspective, we re-evaluate the concept of tissue-resident bacteria including their role in metabolic low-grade tissue and systemic inflammation. We examine the limitations and challenges associated with studying low bacterial biomass samples and propose experimental and analytical strategies to overcome these issues. Our Perspective aims to encourage further investigation of the mechanisms linking tissue-resident bacteria to host metabolism and their potentially actionable health implications for prevention and treatment.
Collapse
Affiliation(s)
- Lucas Massier
- Department of Medicine (H7), Karolinska Institutet, Stockholm, Sweden
| | - Niculina Musat
- Aarhus University, Department of Biology, Section for Microbiology, Århus, Denmark
| | - Michael Stumvoll
- Medical Department III - Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
| | - Valentina Tremaroli
- Wallenberg Laboratory, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Rima Chakaroun
- Medical Department III - Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, Leipzig, Germany.
- Wallenberg Laboratory, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden.
| | - Peter Kovacs
- Medical Department III - Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, Leipzig, Germany.
| |
Collapse
|
2
|
Vitkov L, Muñoz LE, Knopf J, Schauer C, Oberthaler H, Minnich B, Hannig M, Herrmann M. Connection between Periodontitis-Induced Low-Grade Endotoxemia and Systemic Diseases: Neutrophils as Protagonists and Targets. Int J Mol Sci 2021; 22:4647. [PMID: 33925019 PMCID: PMC8125370 DOI: 10.3390/ijms22094647] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/22/2021] [Accepted: 04/26/2021] [Indexed: 12/11/2022] Open
Abstract
Periodontitis is considered a promoter of many systemic diseases, but the signaling pathways of this interconnection remain elusive. Recently, it became evident that certain microbial challenges promote a heightened response of myeloid cell populations to subsequent infections either with the same or other pathogens. This phenomenon involves changes in the cell epigenetic and transcription, and is referred to as ''trained immunity''. It acts via modulation of hematopoietic stem and progenitor cells (HSPCs). A main modulation driver is the sustained, persistent low-level transmission of lipopolysaccharide from the periodontal pocket into the peripheral blood. Subsequently, the neutrophil phenotype changes and neutrophils become hyper-responsive and prone to boosted formation of neutrophil extracellular traps (NET). Cytotoxic neutrophil proteases and histones are responsible for ulcer formations on the pocket epithelium, which foster bacteremia and endoxemia. The latter promote systemic low-grade inflammation (SLGI), a precondition for many systemic diseases and some of them, e.g., atherosclerosis, diabetes etc., can be triggered by SLGI alone. Either reverting the polarized neutrophils back to the homeostatic state or attenuation of neutrophil hyper-responsiveness in periodontitis might be an approach to diminish or even to prevent systemic diseases.
Collapse
Affiliation(s)
- Ljubomir Vitkov
- Vascular & Exercise Biology Unit, Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria; (L.V.); (H.O.); (B.M.)
- Clinic of Operative Dentistry, Periodontology and Preventive Dentistry, Saarland University, 66424 Homburg, Germany
| | - Luis E. Muñoz
- Department of Internal Medicine 3—Rheumatology and Immunology, Universitätsklinikum Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91052 Erlangen, Germany; (L.E.M.); (J.K.); (C.S.); (M.H.)
| | - Jasmin Knopf
- Department of Internal Medicine 3—Rheumatology and Immunology, Universitätsklinikum Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91052 Erlangen, Germany; (L.E.M.); (J.K.); (C.S.); (M.H.)
| | - Christine Schauer
- Department of Internal Medicine 3—Rheumatology and Immunology, Universitätsklinikum Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91052 Erlangen, Germany; (L.E.M.); (J.K.); (C.S.); (M.H.)
| | - Hannah Oberthaler
- Vascular & Exercise Biology Unit, Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria; (L.V.); (H.O.); (B.M.)
| | - Bernd Minnich
- Vascular & Exercise Biology Unit, Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria; (L.V.); (H.O.); (B.M.)
| | - Matthias Hannig
- Clinic of Operative Dentistry, Periodontology and Preventive Dentistry, Saarland University, 66424 Homburg, Germany
| | - Martin Herrmann
- Department of Internal Medicine 3—Rheumatology and Immunology, Universitätsklinikum Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91052 Erlangen, Germany; (L.E.M.); (J.K.); (C.S.); (M.H.)
| |
Collapse
|
3
|
Massier L, Blüher M, Kovacs P, Chakaroun RM. Impaired Intestinal Barrier and Tissue Bacteria: Pathomechanisms for Metabolic Diseases. Front Endocrinol (Lausanne) 2021; 12:616506. [PMID: 33767669 PMCID: PMC7985551 DOI: 10.3389/fendo.2021.616506] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 02/02/2021] [Indexed: 02/06/2023] Open
Abstract
An intact intestinal barrier, representing the interface between inner and outer environments, is an integral regulator of health. Among several factors, bacteria and their products have been evidenced to contribute to gut barrier impairment and its increased permeability. Alterations of tight junction integrity - caused by both external factors and host metabolic state - are important for gut barrier, since they can lead to increased influx of bacteria or bacterial components (endotoxin, bacterial DNA, metabolites) into the host circulation. Increased systemic levels of bacterial endotoxins and DNA have been associated with an impaired metabolic host status, manifested in obesity, insulin resistance, and associated cardiovascular complications. Bacterial components and cells are distributed to peripheral tissues via the blood stream, possibly contributing to metabolic diseases by increasing chronic pro-inflammatory signals at both tissue and systemic levels. This response is, along with other yet unknown mechanisms, mediated by toll like receptor (TLR) transduction and increased expression of pro-inflammatory cytokines, which in turn can further increase intestinal permeability leading to a detrimental positive feedback loop. The modulation of gut barrier function through nutritional and other interventions, including manipulation of gut microbiota, may represent a potential prevention and treatment target for metabolic diseases.
Collapse
Affiliation(s)
- Lucas Massier
- Medical Department III – Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
- Department of Medicine (H7), Karolinska Institutet, Karolinska University Hospital, Huddinge, Stockholm, Sweden
| | - Matthias Blüher
- Medical Department III – Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
- Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München, University Hospital Leipzig, University of Leipzig, Leipzig, Germany
| | - Peter Kovacs
- Medical Department III – Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
| | - Rima M. Chakaroun
- Medical Department III – Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
- *Correspondence: Rima M. Chakaroun,
| |
Collapse
|
4
|
Dargent A, Pais de Barros JP, Saheb S, Bittar R, Le Goff W, Carrié A, Gautier T, Fournel I, Rerole AL, Choubley H, Masson D, Lagrost L, Quenot JP. LDL apheresis as an alternate method for plasma LPS purification in healthy volunteers and dyslipidemic and septic patients. J Lipid Res 2020; 61:1776-1783. [PMID: 33037132 PMCID: PMC7707173 DOI: 10.1194/jlr.ra120001132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Lipopolysaccharide (LPS) is a key player for innate immunity activation. It is therefore a prime target for sepsis treatment, as antibiotics are not sufficient to improve outcome during septic shock. An extracorporeal removal method by polymyxin (PMX) B direct hemoperfusion (PMX-DHP) is used in Japan, but recent trials failed to show a significant lowering of circulating LPS levels after PMX-DHP therapy. PMX-DHP has a direct effect on LPS molecules. However, LPS is not present in a free form in the circulation, as it is mainly carried by lipoproteins, including LDLs. Lipoproteins are critical for physiological LPS clearance, as LPSs are carried by LDLs to the liver for elimination. We hypothesized that LDL apheresis could be an alternate method for LPS removal. First, we demonstrated in vitro that LDL apheresis microbeads are almost as efficient as PMX beads to reduce LPS concentration in LPS-spiked human plasma, whereas it is not active in PBS. We found that PMX was also adsorbing lipoproteins, although less specifically. Then, we found that endogenous LPS of patients treated by LDL apheresis for familial hypercholesterolemia is also removed during their LDL apheresis sessions, with both electrostatic-based devices and filtration devices. Finally, LPS circulating in the plasma of septic shock and severe sepsis patients with gram-negative bacteremia was also removed in vitro by LDL adsorption. Overall, these results underline the importance of lipoproteins for LPS clearance, making them a prime target to study and treat endotoxemia-related conditions.
Collapse
Affiliation(s)
- Auguste Dargent
- Médecine Intensive Réanimation, Hôpital Edouard Herriot, Lyon, France; Université Bourgogne Franche-Comté, LNC, Dijon, France; INSERM, LNC UMR1231, Dijon, France; FCS Bourgogne-Franche Comté, LipSTIC LabEx, Dijon, France.
| | - Jean-Paul Pais de Barros
- Université Bourgogne Franche-Comté, LNC, Dijon, France; INSERM, LNC UMR1231, Dijon, France; FCS Bourgogne-Franche Comté, LipSTIC LabEx, Dijon, France
| | - Samir Saheb
- Service d'endocrinologie et d'aphérèse, Hôpital Pitié Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Randa Bittar
- Service de Biochimie métabolique, Hôpital Pitié Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Wilfried Le Goff
- Sorbonne University, INSERM, Institute of Cardiometabolism and Nutrition (ICAN), UMR_S1166, Hôpital de la Pitié, Paris, France
| | - Alain Carrié
- Sorbonne University, INSERM, Institute of Cardiometabolism and Nutrition (ICAN), UMR_S1166, Hôpital de la Pitié, Paris, France; Hôpitaux Universitaires Pitié-Salpêtrière/Charles-Foix, Department of Biochemistry for Endocrinology and Oncology, Obesity and Dyslipidemia Genetics Unit, Paris, France
| | - Thomas Gautier
- Université Bourgogne Franche-Comté, LNC, Dijon, France; INSERM, LNC UMR1231, Dijon, France; FCS Bourgogne-Franche Comté, LipSTIC LabEx, Dijon, France
| | - Isabelle Fournel
- INSERM, CIC 1432, Module Epidémiologie Clinique, Dijon, France; CHU Dijon-Bourgogne, Centre d'Investigation Clinique, Module Epidémiologie Clinique/Essais Cliniques, Dijon, France
| | - Anne Laure Rerole
- Université Bourgogne Franche-Comté, LNC, Dijon, France; INSERM, LNC UMR1231, Dijon, France; FCS Bourgogne-Franche Comté, LipSTIC LabEx, Dijon, France
| | - Hélène Choubley
- Université Bourgogne Franche-Comté, LNC, Dijon, France; INSERM, LNC UMR1231, Dijon, France; FCS Bourgogne-Franche Comté, LipSTIC LabEx, Dijon, France
| | - David Masson
- Université Bourgogne Franche-Comté, LNC, Dijon, France; INSERM, LNC UMR1231, Dijon, France; FCS Bourgogne-Franche Comté, LipSTIC LabEx, Dijon, France; Service de Biochimie médicale, CHU Dijon, Dijon, France
| | - Laurent Lagrost
- Université Bourgogne Franche-Comté, LNC, Dijon, France; INSERM, LNC UMR1231, Dijon, France; FCS Bourgogne-Franche Comté, LipSTIC LabEx, Dijon, France; Service de Biochimie médicale, CHU Dijon, Dijon, France
| | - Jean-Pierre Quenot
- FCS Bourgogne-Franche Comté, LipSTIC LabEx, Dijon, France; INSERM, CIC 1432, Module Epidémiologie Clinique, Dijon, France; CHU Dijon-Bourgogne, Centre d'Investigation Clinique, Module Epidémiologie Clinique/Essais Cliniques, Dijon, France; Médecine Intensive Réanimation, CHU Dijon, Dijon, France
| |
Collapse
|
5
|
Ponziani FR, Zocco MA, Cerrito L, Gasbarrini A, Pompili M. Bacterial translocation in patients with liver cirrhosis: physiology, clinical consequences, and practical implications. Expert Rev Gastroenterol Hepatol 2018; 12:641-656. [PMID: 29806487 DOI: 10.1080/17474124.2018.1481747] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The gut liver axis is an operative unit that works to protect the human body against potentially harmful substances and microorganisms, maintaining the homeostasis of the immune system. Liver cirrhosis profoundly alters this complex system. The intestine becomes more permeable allowing the translocation of bacteria, bacterial products and fragments into the portal circulation, triggering an abnormal local and systemic inflammatory response and a condition of perpetual immunologic alarm. This immune-inflammatory disorder related to dysbiosis is involved in the development of liver damage and liver cirrhosis complications and increases intestinal permeability in a vicious circle. Areas covered: The most relevant studies on bacterial translocation, the mechanism of intestinal barrier dysfunction and its consequences in patients with liver cirrhosis have been revised through a PubMed search. Data have been discussed with particular regard to their significance in clinical practice. Expert commentary: The assessment of bacterial translocation and intestinal permeability is not currently used in clinical practice but may be useful to stratify patients' prognosis.
Collapse
Affiliation(s)
- Francesca Romana Ponziani
- a Internal Medicine, Gastroenterology and Hepatology , Fondazione Agostino Gemelli Hospital , Rome , Italy
| | - Maria Assunta Zocco
- a Internal Medicine, Gastroenterology and Hepatology , Fondazione Agostino Gemelli Hospital , Rome , Italy
| | - Lucia Cerrito
- a Internal Medicine, Gastroenterology and Hepatology , Fondazione Agostino Gemelli Hospital , Rome , Italy
| | - Antonio Gasbarrini
- a Internal Medicine, Gastroenterology and Hepatology , Fondazione Agostino Gemelli Hospital , Rome , Italy
| | - Maurizio Pompili
- a Internal Medicine, Gastroenterology and Hepatology , Fondazione Agostino Gemelli Hospital , Rome , Italy
| |
Collapse
|
6
|
Abstract
Animals that cannot sense endotoxin may die if they are infected by Gram-negative bacteria. Animals that sense endotoxin and respond too vigorously may also die, victims of their own inflammatory reactions. The outcome of Gram-negative bacterial infection is thus determined not only by an individual's ability to sense endotoxin and respond to its presence, but also by numerous phenomena that inactivate endotoxin and/or prevent harmful reactions to it. Endotoxin sensing requires the MD-2/TLR4 recognition complex and occurs principally in local tissues and the liver. This review highlights the known detoxification mechanisms, which include: (i) proteins that facilitate LPS sequestration by plasma lipoproteins, prevent interactions between the bioactive lipid A moiety and MD-2/TLR4, or promote cellular uptake via non-signaling pathway(s); (ii) enzymes that deacylate or dephosphorylate lipid A; (iii) mechanisms that remove LPS and Gram-negative bacteria from the bloodstream; and (iv) neuroendocrine adaptations that modulate LPS-induced mediator production or neutralize pro-inflammatory molecules in the circulation. In general, the mechanisms for sensing and detoxifying endotoxin seem to be compartmentalized (local versus systemic), dynamic, and variable between individuals. They may have evolved to confine infection and inflammation to extravascular sites of infection while preventing harmful systemic reactions. Integration of endotoxin sensing and detoxification is essential for successful host defense.
Collapse
Affiliation(s)
- Robert S. Munford
- Molecular Host Defense Laboratory, Departments of Internal Medicine and Microbiology, University of Texas Southwestern Medical School, Dallas, Texas, USA,
| |
Collapse
|
7
|
Abstract
Limulus amebocyte lysate (LAL) has been applied to the detection of endotoxin in human serum, plasma and blood since the early 1970s. Although the diagnostic potential of LAL for endotoxemia was recognized immediately, the assay's modest sensitivity and specificity (for Gram-negative sepsis/bacteremia) were perceived as limiting the clinical usefulness of LAL. In an attempt to overcome these drawbacks, many studies have been conducted since the initial work by Levin and his colleagues. Numerous attempts have been made to improve the sensitivity of the assay by changing the formulation of the LAL and assay methodology. The original gel-clot method has for the most part been replaced with turbidimetric or chromogenic methods. The amount of endotoxin detectable within a 1 h incubation period has gone from the nanogram to the picogram range. Since blood (plasma) components interfere with the test, various methods to remove inhibition and/or enhancement have been developed. The chloroform extraction technique of Levin and co-workers has been replaced with acid extraction or with dilution and heating. Partitioning of endotoxin in blood may also influence the assay (recovery). Many recent investigators use platelet-rich plasma instead of ordinary plasma, while a few studies have used whole blood. Even with all the improvements, the specificity and related diagnostic usefulness of the LAL assay for Gram-negative sepsis remain an obstacle for regulatory acceptance. This may have more to do with our understanding of the septic process than with the ability of LAL to detect endotoxin. Although a recent study indicates that the type of Gram-negative bacteremia may be a critical determinant for clinical utility of the LAL test, the presence of endotoxin is not highly predictive of Gram-negative sepsis and vice versa. However, with the potential availability of anti-endotoxin therapy, the diagnosis of endotoxemia, with or without bacteremia, may be extremely important for timely and effective treatment modalities. It is concluded that the LAL test and accompanying sample preparation has evolved into a clinically useful test for the detection of circulating endotoxins and even its modest predictability for sepsis may have some clinical utility.
Collapse
|
8
|
Munford RS. Endotoxemia-menace, marker, or mistake? J Leukoc Biol 2016; 100:687-698. [PMID: 27418356 DOI: 10.1189/jlb.3ru0316-151r] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 06/27/2016] [Indexed: 01/19/2023] Open
Abstract
Endotoxemia is in its scientific ascendancy. Never has blood-borne, Gram-negative bacterial endotoxin (LPS) been invoked in the pathogenesis of so many diseases-not only as a trigger for septic shock, once its most cited role, but also as a contributor to atherosclerosis, obesity, chronic fatigue, metabolic syndrome, and many other conditions. Finding elevated plasma endotoxin levels has been essential supporting evidence for each of these links, yet the assays used to detect and quantitate endotoxin have important limitations. This article describes several assays for endotoxin in plasma, reviews what they do and do not measure, and discusses why LPS heterogeneity, LPS trafficking pathways, and host LPS inactivation mechanisms should be considered when interpreting endotoxin assay results.
Collapse
Affiliation(s)
- Robert S Munford
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, USA
| |
Collapse
|
9
|
Günel A. Modelling the interactions between TLR4 and IFNβ pathways. J Theor Biol 2012; 307:137-48. [PMID: 22575970 DOI: 10.1016/j.jtbi.2012.04.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 04/17/2012] [Accepted: 04/18/2012] [Indexed: 02/06/2023]
Abstract
Bacterial lipopolysaccharide (LPS) association with their connate receptor TLR4 triggers Type I interferon signaling cascade through its MyD88 independent downstream. Compared to plethora of reported empirical data on both TLR4 and Type I interferon pathways, there is no known model to decipher crosstalk mechanisms between these two crucial innate immune pathogen activated pathways regulating vital transcriptional factors such as nuclear factor-κB (NFκB), IFNβ, the interferon-stimulated gene factor-3 (ISGF3) and an important cancer drug target protein kinase-R (PKR). Innate immune system is based on a sensitive balance of intricate interactions. In elucidating these interactions, in silico integration of pathways has great potential. Attempts confined to single pathway may not be effective in truly addressing source of real systems behavior. This is the first report combining toll-like receptor-4 (TLR4) and interferon beta (IFNβ) pathways in a single in silico model, analyzing their interactions, pinpointing the source of delay in PKR late phase activity and limiting the transcription of IFN and PKR by using a method including an statistical physics technique in reaction equations. The model quite successfully recapitulates published interferon regulatory factor-3 (IRF3) and IFNβ data from mouse macrophages and PKR data from mouse embryonic fibroblast cell lines. The simulations end up with an estimate of IRF3, IFNβ, ISGF3 dose dependent profiles mimicking nonlinear dose response characteristic of the system. Involvement of concomitant PKR downstream can unravel elusive mechanisms in specific profiles like NFκB regulation.
Collapse
Affiliation(s)
- Aylin Günel
- Istanbul Technical University Informatics Institute, Maslak, 34469, Istanbul, Turkiye.
| |
Collapse
|
10
|
Lin T, Kwak YH, Sammy F, He P, Thundivalappil S, Sun G, Chao W, Warren HS. Synergistic inflammation is induced by blood degradation products with microbial Toll-like receptor agonists and is blocked by hemopexin. J Infect Dis 2010; 202:624-32. [PMID: 20617898 DOI: 10.1086/654929] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Detection of microbial components by immune cells via Toll-like receptors (TLRs) with subsequent induction of inflammation is essential for host defense. However, an overactive immune response can cause tissue damage and sepsis. The endogenous molecule hemoglobin and its derivative heme are often released into tissue compartments where there is infection in the presence of degrading blood. We found that hemoglobin synergizes with multiple TLR agonists to induce high levels of tumor necrosis factor and interleukin-6 from macrophages and that this synergy is independent of TLR4 and MyD88. In contrast, heme synergized with some but not all TLR agonists studied. Furthermore, the synergy of both hemoglobin and heme with lipopolysaccharide was suppressed by hemopexin, a plasma heme-binding protein. These studies suggest that hemoglobin and heme may substantially contribute to microbe-induced inflammation when bacterial or viral infection coexists with blood degradation and that hemopexin may play a role in controlling inflammation in such settings.
Collapse
Affiliation(s)
- Tian Lin
- Infectious Disease Unit, Massachusetts General Hospital, Boston, MA 02129, USA
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Lectin-like domain of thrombomodulin binds to its specific ligand Lewis Y antigen and neutralizes lipopolysaccharide-induced inflammatory response. Blood 2008; 112:3661-70. [PMID: 18711002 DOI: 10.1182/blood-2008-03-142760] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Thrombomodulin (TM), a widely expressing glycoprotein originally identified in vascular endothelium, is an important cofactor in the protein C anticoagulant system. TM appears to exhibit anti-inflammatory ability through both protein C-dependent and -independent pathways. We presently have demonstrated that recombinant N-terminal lectinlike domain of TM (rTMD1) functions as a protective agent against sepsis caused by Gram-negative bacterial infections. rTMD1 caused agglutination of Escherichia coli and Klebsiella pneumoniae and enhanced the macrophage phagocytosis of these Gram-negative bacteria. Moreover, rTMD1 bound to the Klebsiella pneumoniae and lipopolysaccharide (LPS) by specifically interacting with Lewis Y antigen. rTMD1 inhibited LPS-induced inflammatory mediator production via interference with CD14 and LPS binding. Furthermore, rTMD1 modulated LPS-induced mitogen-activated protein kinase and nuclear factor-kappaB signaling pathway activations and inducible nitric oxide synthase expression in macrophages. Administration of rTMD1 protected the host by suppressing inflammatory responses induced by LPS and Gram-negative bacteria, and enhanced LPS and bacterial clearance in sepsis. Thus, rTMD1 can be used to defend against bacterial infection and inhibit LPS-induced inflammatory responses, suggesting that rTMD1 may be valuable in the treatment of severe inflammation in sepsis, especially in Gram-negative bacterial infections.
Collapse
|
12
|
Wu A, Hinds CJ, Thiemermann C. High-density lipoproteins in sepsis and septic shock: metabolism, actions, and therapeutic applications. Shock 2004; 21:210-21. [PMID: 14770033 DOI: 10.1097/01.shk.0000111661.09279.82] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sepsis and septic shock are important causes of morbidity and lethality in noncoronary intensive care units. Circulating levels of high-density lipoproteins (HDLs) are reduced in sepsis/septic shock, and the magnitude of this reduction is positively correlated with the severity of the illness. The mechanisms underlying this phenomenon are incompletely understood, although increased levels of several acute-phase proteins, including serum amyloid A (SAA) and secretory phospholipase A2 (sPLA2), may contribute to the decrease in plasma HDLs. It has been suggested that HDLs possess anti-inflammatory properties and, hence, may play a crucial role in innate immunity by regulating the inflammatory response as well as being capable of reducing the severity of organ injury in animals and patients with septic shock. These protective effects of HDLs are mediated mainly via (a) lipopolysaccharide (LPS) binding and neutralization, (b) the HDL-associated enzymes, plasma paraoxonase (PON1) and platelet-activating factor acetylhydrolase (PAF-AH), which protect low-density lipoproteins against peroxidative damage, (c) inhibition of the expression of endothelial cell adhesion molecules and release of proinflammatory cytokines, which prevents inflammatory cell infiltration and subsequent multiple organ dysfunction, and (d) stimulation of the expression of endothelial nitric oxide synthase (eNOS). Thus, HDL exerts potent anti-inflammatory effects, some of which are independent of endotoxin binding and might be useful in the treatment of patients with not only sepsis/septic shock but also other conditions associated with an uncontrolled inflammatory response, such as ischemia-reperfusion injury and hemorrhagic shock.
Collapse
Affiliation(s)
- Aihua Wu
- Department of Anaesthesia, Beijing Hospital, Beijing 100730, PR China
| | | | | |
Collapse
|
13
|
Van Amersfoort ES, Van Berkel TJC, Kuiper J. Receptors, mediators, and mechanisms involved in bacterial sepsis and septic shock. Clin Microbiol Rev 2003; 16:379-414. [PMID: 12857774 PMCID: PMC164216 DOI: 10.1128/cmr.16.3.379-414.2003] [Citation(s) in RCA: 500] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Bacterial sepsis and septic shock result from the overproduction of inflammatory mediators as a consequence of the interaction of the immune system with bacteria and bacterial wall constituents in the body. Bacterial cell wall constituents such as lipopolysaccharide, peptidoglycans, and lipoteichoic acid are particularly responsible for the deleterious effects of bacteria. These constituents interact in the body with a large number of proteins and receptors, and this interaction determines the eventual inflammatory effect of the compounds. Within the circulation bacterial constituents interact with proteins such as plasma lipoproteins and lipopolysaccharide binding protein. The interaction of the bacterial constituents with receptors on the surface of mononuclear cells is mainly responsible for the induction of proinflammatory mediators by the bacterial constituents. The role of individual receptors such as the toll-like receptors and CD14 in the induction of proinflammatory cytokines and adhesion molecules is discussed in detail. In addition, the roles of a number of other receptors that bind bacterial compounds such as scavenger receptors and their modulating role in inflammation are described. Finally, the therapies for the treatment of bacterial sepsis and septic shock are discussed in relation to the action of the aforementioned receptors and proteins.
Collapse
Affiliation(s)
- Edwin S Van Amersfoort
- Division of Biopharmaceutics, Leiden/Amsterdam Center of Drug Research, Leiden University, Leiden, The Netherlands
| | | | | |
Collapse
|
14
|
Levels JHM, Abraham PR, van Barreveld EP, Meijers JCM, van Deventer SJH. Distribution and kinetics of lipoprotein-bound lipoteichoic acid. Infect Immun 2003; 71:3280-4. [PMID: 12761109 PMCID: PMC155762 DOI: 10.1128/iai.71.6.3280-3284.2003] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipoteichoic acid (LTA), a major cell wall component of gram-positive bacteria, is an amphipathic anionic glycolipid with structural similarities to lipopolysaccharide (LPS) from gram-negative bacteria. LTA has been implicated as one of the primary immunostimulatory components that may trigger the systemic inflammatory response syndrome. Plasma lipoproteins have been shown to sequester LPS, which results in attenuation of the host response to infection, but little is known about the LTA binding characteristics of plasma lipid particles. In this study, we have examined the LTA binding capacities and association kinetics of the major lipoprotein classes under simulated physiological conditions in human whole blood (ex vivo) by using biologically active, fluorescently labeled LTA and high-performance gel permeation chromatography. The average distribution of an LTA preparation from Staphylococcus aureus in whole blood from 10 human volunteers revealed that >95% of the LTA was associated with total plasma lipoproteins in the following proportions: high-density lipoprotein (HDL), 68% +/- 10%; low-density lipoprotein (LDL), 28% +/- 8%; and very low density lipoprotein (VLDL), 4% +/- 5%. The saturation capacity of lipoproteins for LTA was in excess of 150 micro g/ml. The LTA distribution was temperature dependent, with an optimal binding between 22 and 37 degrees C. The binding of LTA by lipoproteins was essentially complete within 10 min and was followed by a subsequent redistribution from HDL and VLDL to LDL. We conclude that HDL has the highest binding capacity for LTA and propose that the loading and redistribution of LTA among plasma lipoproteins is a specific process that closely resembles that previously described for LPS (J. H. M. Levels, P. R. Abraham, A. van den Ende, and S. J. H. van Deventer, Infect. Immun. 68:2821-2828, 2001).
Collapse
Affiliation(s)
- Johannes H M Levels
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands.
| | | | | | | | | |
Collapse
|
15
|
Pöschl JMB, Leray C, Ruef P, Cazenave JP, Linderkamp O. Endotoxin binding to erythrocyte membrane and erythrocyte deformability in human sepsis and in vitro. Crit Care Med 2003; 31:924-8. [PMID: 12627006 DOI: 10.1097/01.ccm.0000055366.24147.80] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Several studies have shown that lipopolysaccharide and lipid A impair red blood cell deformability and. However, it is unclear whether impaired red blood cell deformability is associated with binding of lipopolysaccharide to the red blood cell membrane. DESIGN Analysis of hydroxymyristic acid content in red blood cell membranes and red blood cell deformation in patients with Gram-negative septicemia and after incubation of red blood cells from healthy adults with 100 microg of lipid A or 1 mg of lipopolysaccharide per milliliter of red blood cell in buffer solution and in whole blood. Hydroxymyristic acid is a fatty acid of the lipid A part of lipopolysaccharide in most Gram-negative bacteria. SETTING University research laboratories. SUBJECTS Ten healthy adults and four patients with clinical and laboratory signs of septicemia. INTERVENTIONS Blood sampling. MEASUREMENTS AND MAIN RESULTS Red blood cell deformation was measured with a laser-diffraction shearing device (Rheodyn) and a computerized micropore filtration system (CTA). Lipopolysaccharide and lipid A binding to red blood cell membranes was studied by measuring the amide-linked hydroxymyristic acid by gas chromatography. The detection rates of hydroxymyristic acid were 82% for lipopolysaccharide and 79% for lipid A in buffer solution. In membranes of washed red blood cell, the detection rates of lipopolysaccharide and lipid A were 0.26 +/- 0.03% (2.6 +/- 0.3 microg/mL) and 1.3 +/- 0.5% (1.3 +/- 0.5 microg/mL), and in red blood cell membranes of whole blood the detection rates were 2.6% (25.5 microg/mL) and 4.1% (4.1 microg/mL), respectively. The lipopolysaccharide content in red blood cell membranes of septic patients ranged from 47 to 103 microg/mL of red blood cell. Red blood cell deformation in the Rheodyn and in the CTA were not influenced by lipopolysaccharide incubated with washed red blood cells. In the Rheodyn, red blood cell deformation was significantly decreased by 18% after lipid A incubation in washed red blood cells, by 26% after lipopolysaccharide incubation in whole blood, and by 31% in septic patients. Similar effects were observed when we used the CTA. CONCLUSIONS Red blood cell deformation is decreased in septic patients, after incubation of washed red blood cells with lipid A and of whole blood with lipopolysaccharide. Lipopolysaccharide did not influence red blood cell deformation after incubation with washed red blood cells. The decrease of red blood cell deformation was related to the amount of hydroxymyristic acid measured in red blood cell membranes, suggesting that endotoxin binding directly affects mechanical properties of red blood cells.
Collapse
Affiliation(s)
- Johannes M B Pöschl
- Division of Neonatology, Department of Pediatrics, University of Heidelberg Medical School, Germany.
| | | | | | | | | |
Collapse
|
16
|
Levels JH, Abraham PR, van den Ende A, van Deventer SJ. Distribution and kinetics of lipoprotein-bound endotoxin. Infect Immun 2001; 69:2821-8. [PMID: 11292694 PMCID: PMC98230 DOI: 10.1128/iai.69.5.2821-2828.2001] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Lipopolysaccharide (LPS), the major glycolipid component of gram-negative bacterial outer membranes, is a potent endotoxin responsible for pathophysiological symptoms characteristic of infection. The observation that the majority of LPS is found in association with plasma lipoproteins has prompted the suggestion that sequestering of LPS by lipid particles may form an integral part of a humoral detoxification mechanism. Previous studies on the biological properties of isolated lipoproteins used differential ultracentrifugation to separate the major subclasses. To preserve the integrity of the lipoproteins, we have analyzed the LPS distribution, specificity, binding capacity, and kinetics of binding to lipoproteins in human whole blood or plasma by using high-performance gel permeation chromatography and fluorescent LPS of three different chemotypes. The average distribution of O111:B4, J5, or Re595 LPS in whole blood from 10 human volunteers was 60% (+/-8%) high-density lipoprotein (HDL), 25% (+/-7%) low-density lipoprotein, and 12% (+/-5%) very low density lipoprotein. The saturation capacity of lipoproteins for all three LPS chemotypes was in excess of 200 microg/ml. Kinetic analysis however, revealed a strict chemotype dependence. The binding of Re595 or J5 LPS was essentially complete within 10 min, and subsequent redistribution among the lipoprotein subclasses occurred to attain similar distributions as O111:B4 LPS at 40 min. We conclude that under simulated physiological conditions, the binding of LPS to lipoproteins is highly specific, HDL has the highest binding capacity for LPS, the saturation capacity of lipoproteins for endotoxin far exceeds the LPS concentrations measured in clinical situations, and the kinetics of LPS association with lipoproteins display chemotype-dependent differences.
Collapse
Affiliation(s)
- J H Levels
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands.
| | | | | | | |
Collapse
|
17
|
de Haas CJ, van Leeuwen HJ, Verhoef J, van Kessel KP, van Strijp JA. Analysis of lipopolysaccharide (LPS)-binding characteristics of serum components using gel filtration of FITC-labeled LPS. J Immunol Methods 2000; 242:79-89. [PMID: 10986391 DOI: 10.1016/s0022-1759(00)00207-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Lipopolysaccharide (LPS)-binding components in serum play an important role in modifying LPS toxicity. We analyzed the binding characteristics of LPS in the presence of serum using gel filtration of FITC-labeled LPS (FITC-LPS) with on line detection of optical density and fluorescence. FITC-LPS separately behaves as an aggregate resulting in a low, dequenched, fluorescence. Binding of single LPS molecules, segregated from the aggregate, to serum components results in an increase in the fluorescence due to dequenching, and a comigration of fluorescence and optical density signals using gel filtration. This method, in combination with the use of specific antibodies inducing additional shifts, demonstrated that in serum high-density lipoproteins (HDL), albumin and low-density lipoproteins (LDL) were able to monomerize LPS. An ELISA on collected fractions of the gel filtration revealed binding of the recently identified LPS-binding protein, serum amyloid P component (SAP), to the high molecular weight LPS aggregate. In serum, binding of soluble CD14 (sCD14) and LPS-binding protein (LBP) to LPS could not be detected. However, this was probably due to an overshadowing effect of albumin, as an extra addition of recombinant sCD14 to serum clearly monomerized FITC-LPS. Biosensor technology revealed that, of all LPS-binding components tested, only SAP clearly bound to the LPS-coated sensor chip. These results show that gel filtration of FITC-LPS is a quick and reliable method to study the binding characteristics of LPS-binding components.
Collapse
Affiliation(s)
- C J de Haas
- Eijkman Winkler Institute for Medical Microbiology, Department of Inflammation, University Medical Center Utrecht, Utrecht, The Netherlands.
| | | | | | | | | |
Collapse
|
18
|
Zuckerman SH, Evans GF, Bryan N. Interactions of recombinant hemoglobin (rHb1.1) and endotoxin in vivo: effects on systemic tumor necrosis factor and interleukin-6 levels in lethal and sublethal murine models of endotoxemia. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 1997; 130:427-35. [PMID: 9358082 DOI: 10.1016/s0022-2143(97)90043-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effects of acellular hemoglobin-based oxygen carriers in preclinical models of sepsis and endotoxemia have been inconclusive with regard to outcomes reported for survival. In the present study, mice were infused with 1 gm/kg of recombinant human hemoglobin, rHb1.1, and the effects on mortality and systemic tumor necrosis factor (TNF) and interleukin-6 (IL-6) levels were determined by using both lethal and sublethal bolus endotoxin challenge. Pretreatment of mice with rHb1.1 and challenge with 20 mg/kg of lipopolysaccharide (LPS) at an LD100 resulted in a 100% mortality rate by 20 hours, whereas the same mortality rate with the vehicle or 5% albumin groups occurred at 50 hours. Mice challenged with lower LPS concentrations of 10 and 2.5 mg/kg, corresponding to LD15 and LD0, respectively, had 100% and 17% mortality rates in the rHb group and 17% and 0% mortality rates in the vehicle-treated animals. These doses of LPS resulted in maximal increases in systemic TNF, and there were only modest differences between the rHb and the vehicle groups at LPS challenge doses of 2.5 and 20 mg/kg, whereas no difference was observed at the 10 mg/kg concentration. At LPS concentrations below 10 microg/kg, the increases in circulating TNF were dose dependent and no differences were observed in serum TNF levels between the rHb1.1 and vehicle groups. In addition, there were generally no differences in IL-6 levels between the experimental groups, although at 10 mg/kg LPS, a twofold increase in plasma IL-6 levels over those in the controls was observed in the rHb1.1-treated animals. Infusion of rHb1.1 alone did not induce any increase in circulating IL-6 or TNF. These data demonstrate that endotoxin exacerbation, although apparent, was observed only at the highest doses of LPS and that at lower concentrations, there were no differences in the extent of cytokine elevation or in survival rate when rHb1.1-, albumin-, or vehicle-pretreated animals were compared.
Collapse
Affiliation(s)
- S H Zuckerman
- Division of Cardiovascular Research, Lilly Research Laboratories, Indianapolis, IN 46285, USA
| | | | | |
Collapse
|
19
|
Schäfer C, Greiner B, Landig J, Feil E, Schütz ET, Bode JC, Bode C. Decreased endotoxin-binding capacity of whole blood in patients with alcoholic liver disease. J Hepatol 1997; 26:567-73. [PMID: 9075664 DOI: 10.1016/s0168-8278(97)80422-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND/AIMS The proinflammatory effects of endotoxemia, which is often observed in alcohol-abusing patients with various degrees of liver disease, may be modulated by changes in the concentration of endotoxin binding factors. Therefore, the plasma endotoxin concentration and the overall endotoxin binding capacity of whole blood were measured in these patients. METHODS Patients with minor (A1; n=27), more pronounced (A2; n=13), cirrhotic alcoholic liver disease (A3; n=18), and non-alcoholic cirrhosis (NC; n=6), and 15 healthy control persons (HC) were included in the study. Endotoxin plasma levels were determined using a standardized limulus assay. A modified assay was applied to additionally detect tightly bound endotoxin. To measure the endotoxin-binding capacity, aliquots of whole blood were incubated with serial dilutions of endotoxin, supernatants were obtained, and endotoxin retrieval was estimated by addition of limulus lysate, followed by photometric measurement of the maximal reaction velocity (dODmax). Endotoxin binding capacity equals the endotoxin concentration at which dODmax reaches a predefined threshold. RESULTS All groups of alcohol abusers had significantly elevated endotoxin plasma levels with a considerable portion of 'bound' endotoxin. Conversely, the endotoxin binding capacity was markedly diminished, mainly in patients with more advanced liver disease (A1: 85.8% of the control value [non-significant vs. controls]; A2: 25.4% [p<0.05]; A3: 43.6% [p<0.02], NC: 43.2%). CONCLUSIONS The endotoxin-binding capacity is diminished in patients with alcoholic and non-alcoholic cirrhosis, as well as in less advanced alcoholic liver disease. Reduced endotoxin binding may contribute to the adverse effects of endotoxemia.
Collapse
Affiliation(s)
- C Schäfer
- Department of Internal Medicine, Hohenheim University, Stuttgart, Germany
| | | | | | | | | | | | | |
Collapse
|
20
|
Yoshida M, Roth RI, Grunfeld C, Feingold KR, Levin J. Soluble (1-->3)-beta-D-glucan purified from Candida albicans: biologic effects and distribution in blood and organs in rabbits. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 1996; 128:103-14. [PMID: 8759942 DOI: 10.1016/s0022-2143(96)90119-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
(1-->3)-beta-D-glucan is a ubiquitous constituent of fungi, and elevated plasma glucan levels are commonly present in patients with deep mycosis or fungemia. The pharmacokinetics, biologic effects, and distribution in blood and organs of iodine 125-labeled (1--> 3)-beta-D-glucan purified from Candida albicans organisms were analyzed in rabbits during the 24-hour period after intravenous administration of this constituent. The intravascular half-life of beta-glucan was 1.8 minutes in the low-dose group (9.3 micrograms/kg, n = 3) and 1.4 minutes in the high-dose group (222 micrograms/kg, n = 3), and the total body clearance was 1.12 +/- 0.30 ml/min and 1.17 +/- 0.16 ml/min (mean +/- SD), respectively (not significantly different). The serum concentration of (1-->3)-beta-D-glucan was also biologically determined by a test using coagulation factor G of the Japanese horse-shoe crab (G test). There was good correlation between the clearance of beta-glucan measured biologically and isotopically. During the 24-hour period of observation the rabbits remained well and beta-glucan failed to alter blood cell counts, tumor necrosis factor levels, or lipid metabolism. 125I-labeled beta-glucan associated with the blood cellular compartment initially was less than 3% (the majority in the platelets) and decreased further during the following 2-hour period. Over 97% of circulating 125I-labeled beta-glucan was associated with the cell-free plasma, and the majority of this glucan in plasma appeared not to be associated with lipoproteins. The liver contained more than 80% of the 125I-labeled beta-glucan detected in the six major organs analyzed.
Collapse
Affiliation(s)
- M Yoshida
- Department of Laboratory Medicine, University of California School of Medicine, San Francisco, USA
| | | | | | | | | |
Collapse
|
21
|
Cutler CW, Eke PI, Genco CA, Van Dyke TE, Arnold RR. Hemin-induced modifications of the antigenicity and hemin-binding capacity of Porphyromonas gingivalis lipopolysaccharide. Infect Immun 1996; 64:2282-7. [PMID: 8675338 PMCID: PMC174067 DOI: 10.1128/iai.64.6.2282-2287.1996] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Previous studies have shown that the physical, biochemical, and antigenic properties of the bacterial outer membrane are profoundly influenced by the growth environment. In the present study, the effects of growth in hemin-replete (H+) and hemin-depleted (H-) media on the lipopolysaccharide (LPS) of the oral pathogen Porphyromonas gingivalis were investigated. Our studies show that LPS from P. gingivalis cultured in H+ media (H+LPS) expressed additional low-molecular-mass antigens, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (immunoblot) analysis. Particularly evident was a 26-kDa antigen (26 LPSC) that was lost from the LPS upon transfer of P. gingivalis into H- media. The loss of the 26 LPSC was accompanied by a marked reduction in the hemin-binding capacity of the LPS. The 26 LPSC was refractory to Coomassie blue staining and proteinase K digestion. H+LPS from strain W50/BE1, a nonpigmented pleiotropic strain, lacked the 26 LPSC and did not bind hemin. Polyclonal antiserum raised to whole-cell antigens of P. gingivalis A7436, W83, and HG405 grown in H+ media, but not in H- media, recognized the 26 LPSC in the purified H+LPS from any of the three strains. The immunoreactivities of sera from humans with (n = 24) or without (n = 25) periodontitis to the 26 LPSC and other H+LPS determinants were analyzed by Western blot. Overall, 75% of adult periodontitis patient sera reacted with multiple bands in the H+LPS stepladder, particularly in the range of 14 to 27 kDa. In contrast, only 20% of control sera reacted faintly with H+LPS bands in the range 27 to 34 kDa. The 26 LPSC was recognized by over 40% of sera from adult patients with periodontitis and none of the healthy control sera. Taken together, these results suggest that the antigenicity and hemin-binding properties of P. gingivalis LPS can be modified by growth in H+ media.
Collapse
Affiliation(s)
- C W Cutler
- Department of Biomedical Sciences and Periodontics, Baylor College of Dentistry, Dallas, Texas, USA
| | | | | | | | | |
Collapse
|
22
|
Schlichting E, Aspelin T, Lyberg T. Interactions of endotoxin with human blood cells and serum proteins. Scand J Clin Lab Invest 1996; 56:167-76. [PMID: 8743110 DOI: 10.3109/00365519609088604] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Endotoxin interacts with several plasma protein systems and blood cells, causing release of a multitude of endogenous mediators that contribute to the pathophysiological process of sepsis. Binding of 125I-labelled lipopolysaccharide, LPS, to human blood in vitro showed that the major part of the 125I-LPS was recovered in plasma, whereas only small amounts were retained in washed suspensions of granulocytes, erythrocytes, monocytes and lymphocytes, respectively. Whole leukocyte preparations or isolated subpopulations incubated with 125I-LPS or fluorescein-conjugated LPS followed by autoradiography, flow cytometry or immunofluorescence microscopy showed unequivocally that monocytes bound much more LPS than did granulocytes and lymphocytes. Lipoprotein electrophoresis followed by autoradiography showed that 125I-LPS bound to all the purified lipoprotein fractions, which was also confirmed by gel filtration chromatography. These findings demonstrate that monocytes represent the most important blood cell for LPS binding and that radiolabelled LPS is able to bind to lipoproteins as well as to other serum constituents.
Collapse
Affiliation(s)
- E Schlichting
- Department of Surgery, Ullevaal University Hospital, Oslo, Norway
| | | | | |
Collapse
|
23
|
Zhang GH, Baek L, Bertelsen T, Koch C. Quantification of the endotoxin-neutralizing capacity of serum and plasma. APMIS 1995; 103:721-30. [PMID: 8534431 DOI: 10.1111/j.1699-0463.1995.tb01429.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A new procedure for quantifying the endotoxin-neutralizing capacity (ENC) of plasma or serum is described. Serially diluted samples were preincubated with endotoxin (lipopolysaccharide; LPS) and the sample dilution producing 50% inhibition of Tachypleus amebocyte lysate activation was measured by a Limulus peptide C enzyme-linked immunosorbent assay. The assay was not subject to interference from plasma or serum at a 500-fold dilution. The ENC of fresh sera from 120 healthy human donors, determined with Salmonella abortus LPS, had a median value of 7.7 kEU/ml (95% confidence limits 3-24 kEU/ml). Values for heparinized fresh plasma were close to those for the corresponding sera. Serum ENC varied greatly with different types of LPS. Neutralization of LPS by serum was rapid, heat-labile, and fully reversed by acidification. Addition of 2 mM EDTA to the serum diluent or pretreatment of LPS with 0.5% deoxycholate enhanced the ENC of serum about 25-fold or 10-fold respectively. The neutralization of LPS by polymyxin B or lysozyme could be demonstrated by the ENC assay, while that by human serum albumin, fibronectin or anti-LPS immunoglobulins was only detected in the presence of 2 mM EDTA. The kinetic changes of LPS and ENC during rabbit endotoxemia were also determined. The ENC assay may be used to study the significance of plasma ENC in Gram-negative infections and to identify the components contributing to plasma ENC.
Collapse
Affiliation(s)
- G H Zhang
- Division of Immunology, Statens Seruminstitut, Copenhagen, Denmark
| | | | | | | |
Collapse
|
24
|
Abstract
As an assay for endotoxin, the Limulus amebocyte lysate assay has several desirable properties: sensitivity, specificity, and potential for adaptation to a quantitative format. Several modifications have been developed to enhance its potential for clinical application. The modifications that allow quantitative measurement of endotoxin and also improve its application to blood samples are described in this review. In fluids other than blood, the detection of endotoxin with the Limulus amebocyte lysate assay can be used as an aid to identify the presence of gram-negative bacteria, and the assay has established utility. With blood, however, there are a range of factors that interfere with the detection of endotoxemia and there are disparate views with respect to the diagnostic and prognostic significance of the test results. In general, the clinical significance of the finding of endotoxemia broadly parallels the frequency and importance of gram-negative sepsis in the patient groups studied and a decline in endotoxin levels accompanies clinical improvement. However, with therapies designed to reduce levels of endotoxin, or to antagonize its effects, it is unclear whether clinical improvement occurs as a consequence of changes in the levels of endotoxemia.
Collapse
Affiliation(s)
- J C Hurley
- Division of Infectious Diseases, Children's Hospital & Medical Center, Seattle, Washington, USA
| |
Collapse
|
25
|
Bélanger M, Bégin C, Jacques M. Lipopolysaccharides of Actinobacillus pleuropneumoniae bind pig hemoglobin. Infect Immun 1995; 63:656-62. [PMID: 7822035 PMCID: PMC173045 DOI: 10.1128/iai.63.2.656-662.1995] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
A previous study indicated that lipopolysaccharides (LPS) extracted from Actinobacillus pleuropneumoniae bind two low-molecular-mass proteins, of approximately 10 and 11 kDa, present in porcine respiratory tract secretions (M. Bélanger, D. Dubreuil, and M. Jacques, Infect. Immun. 62:868-873, 1994). In the present study, we determined the N-terminal amino acid sequences of these two proteins, which revealed high homology with the alpha and beta chains of pig hemoglobin. Some isolates of A. pleuropneumoniae were able to use hemoglobin from various animal species as well as other heme compounds as sole sources of iron for growth, while other isolates were unable to use them. Immunoelectron microscopy showed binding of pig hemoglobin at the surface of all A. pleuropneumoniae isolates as well as labeling of outer membrane blebs. We observed, using Western blotting (immunoblotting), that the lipid A-core region of LPS of all isolates was binding pig hemoglobin. Furthermore, lipid A obtained after acid hydrolysis of LPS extracted from A. pleuropneumoniae was able to bind pig hemoglobin and this binding was completely abolished by preincubation of lipid A with polymyxin B but was not inhibited by preincubation with glucosamines. Fatty acids constituting the lipid A of A. pleuropneumoniae, namely, dodecanoic acid, tetradecanoic acid, 3-hydroxytetradecanoic acid, hexadecanoic acid, and octadecanoic acid, were also binding pig hemoglobin. Our results indicate that LPS of all A. pleuropneumoniae isolates tested bind pig hemoglobin and that lipid A is involved in this binding. Our results also indicate that some A. pleuropneumoniae isolates are, in addition, able to use hemoglobin for growth. Binding of hemoglobin to LPS might represent an important means by which A. pleuropneumoniae acquires iron in vivo from hemoglobin released from erythrocytes lysed by the action of its hemolysins.
Collapse
Affiliation(s)
- M Bélanger
- Département de pathologie et microbiologie, Faculté de Médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
| | | | | |
Collapse
|
26
|
Cliff RO, Kwasiborski V, Rudolph AS. A comparative study of the accurate measurement of endotoxin in liposome-encapsulated hemoglobin. ARTIFICIAL CELLS, BLOOD SUBSTITUTES, AND IMMOBILIZATION BIOTECHNOLOGY 1995; 23:331-6. [PMID: 7493054 DOI: 10.3109/10731199509117949] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have examined three different methods of endotoxin determination utilizing the Limulus Amebocyte Lysate (LAL) assay to accurately determine endotoxin levels in Liposome Encapsulated Hemoglobin (LEH), 1) the gel-clot method, 2) chromogenic spectroscopic-based LAL, and 3) the turbidimetric method which determines endotoxin levels in solutions based on the time needed to reach a specific degree of turbidity. Both the chromogenic and turbidimetric methods require significant dilution of the LEH preparation before accurate measurement can be made. We have tested the levels of endotoxin in LEH solutions using these methods and measured LEH, liposome, and hemoglobin samples spiked with known amounts of endotoxin. A comparison of the three methods shows that the absolute value of endotoxin measured in LEH by the three methods can vary significantly. However, within any one assay the spiked amount of endotoxin in the sample can be accurately measured. The accuracy of these methods may also be complicated by the binding of endotoxin to LEH. This was evident by mixing free endotoxin with LEH followed by centrifugation to separate the LEH. Biological activity of endotoxin bound to LEH was measured by exposure to RAW264.7 followed by the expression of tumor necrosis factor.
Collapse
Affiliation(s)
- R O Cliff
- Center for BioMolecular Science and Engineering, Naval Research Laboratory, Washington, DC 20375-5348, USA
| | | | | |
Collapse
|