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Center SA, Randolph JF, Warner KL, McDonough SP, Lucy JM, Sapa KC. Bacterial culture and immunohistochemical detection of bacteria and endotoxin in cats with suppurative cholangitis-cholangiohepatitis syndrome. J Am Vet Med Assoc 2021; 260:194-211. [PMID: 34936576 DOI: 10.2460/javma.20.10.0552] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE To characterize the frequency and type of bacterial infection by culture- and immunohistochemical (IHC)-based methods and determine the impact of infection on clinical features and survival time in cats with suppurative cholangitis-cholangiohepatitis syndrome (S-CCHS). ANIMALS 168 client-owned cats with S-CCHS (cases). PROCEDURES Clinical features, bacterial culture results, culture-inoculate sources, and survival details were recorded. Cases were subcategorized by comorbidity (extrahepatic bile duct obstruction, cholelithiasis, cholecystitis, ductal plate malformation, biopsy-confirmed inflammatory bowel disease, and biopsy-confirmed pancreatitis) or treatment by cholecystectomy or cholecystoenterostomy. Culture results, bacterial isolates, Gram-stain characteristics, and IHC staining were compared among comorbidities. Lipoteichoic acid IHC staining detected gram-positive bacterial cell wall components, and toll-like receptor expression IHC reflected pathologic endotoxin (gram-negative bacteria) exposure. RESULTS Clinical features were similar among cases except for more frequent abdominal pain and lethargy in cats with positive culture results and pyrexia, abdominal pain, and hepatomegaly for cats with polymicrobial infections. Bacteria were cultured in 93 of 135 (69%) cats, with common isolates including Enterococcus spp and Escherichia coli. IHC staining was positive in 142 of 151 (94%) cats (lipoteichoic acid, 107/142 [75%]; toll-like receptor 4, 99/142 [70%]). With in-parallel interpretation of culture and IHC-based bacterial detection, 154 of 166 (93%) cats had bacterial infections (gram-positive, 118/154 [77%]; gram-negative, 111/154 [72%]; polymicrobial, 79/154 [51%]). Greater frequency of bacterial isolation occurred with combined tissue, bile, and crushed cholelith inoculates. Infection and gram-positive bacterial isolates were associated with significantly shorter long-term survival times. CLINICAL RELEVANCE S-CCHS was associated with bacterial infection, pathologic endotoxin exposure, and frequent polymicrobial infection in cats. Combined tissue inoculates improved culture detection of associated bacteria.
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Affiliation(s)
- Sharon A Center
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - John F Randolph
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Karen L Warner
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Sean P McDonough
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | | | - Kirk C Sapa
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
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Pérez-Hernández EG, Delgado-Coello B, Luna-Reyes I, Mas-Oliva J. New insights into lipopolysaccharide inactivation mechanisms in sepsis. Biomed Pharmacother 2021; 141:111890. [PMID: 34229252 DOI: 10.1016/j.biopha.2021.111890] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/03/2021] [Accepted: 06/28/2021] [Indexed: 02/06/2023] Open
Abstract
The complex pathophysiology of sepsis makes it a syndrome with limited therapeutic options and a high mortality rate. Gram-negative bacteria containing lipopolysaccharides (LPS) in their outer membrane correspond to the most common cause of sepsis. Since the gut is considered an important source of LPS, intestinal damage has been considered a cause and a consequence of sepsis. Although important in the maintenance of the intestinal epithelial cell homeostasis, the microbiota has been considered a source of LPS. Recent studies have started to shed light on how sepsis is triggered by dysbiosis, and an increased inflammatory state of the intestinal epithelial cells, expanding the understanding of the gut-liver axis in sepsis. Here, we review the gut-liver interaction in Gram-negative sepsis, exploring the mechanisms of LPS inactivation, including the recently described contribution of an isoform of the cholesteryl-ester transfer protein (CETPI). Although several key questions remain to be answered when the pathophysiology of sepsis is reviewed, new contributions coming to light exploring the way LPS might be inactivated in vivo, suggest that new applications might soon reach the clinical setting.
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Affiliation(s)
| | - Blanca Delgado-Coello
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico
| | - Ismael Luna-Reyes
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico
| | - Jaime Mas-Oliva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico.
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Low-density lipoprotein (LDL)-dependent uptake of Gram-positive lipoteichoic acid and Gram-negative lipopolysaccharide occurs through LDL receptor. Sci Rep 2018; 8:10496. [PMID: 30002483 PMCID: PMC6043579 DOI: 10.1038/s41598-018-28777-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 06/26/2018] [Indexed: 12/29/2022] Open
Abstract
Lipoteichoic acid (LTA) and lipopolysaccharide (LPS) are bacterial lipids that stimulate pro-inflammatory cytokine production, thereby exacerbating sepsis pathophysiology. Proprotein convertase subtilisin/kexin type 9 (PCSK9) negatively regulates uptake of cholesterol by downregulating hepatic lipoprotein receptors, including low-density lipoprotein (LDL) receptor (LDLR) and possibly LDLR-related protein-1 (LRP1). PCSK9 also negatively regulates Gram-negative LPS uptake by hepatocytes, however this mechanism is not completely characterized and mechanisms of Gram-positive LTA uptake are unknown. Therefore, our objective was to elucidate the mechanisms through which PCSK9 regulates uptake of LTA and LPS by investigating the roles of lipoproteins and lipoprotein receptors. Here we show that plasma PCSK9 concentrations increase transiently over time in septic and non-septic critically ill patients, with highly similar profiles over 14 days. Using flow cytometry, we demonstrate that PCSK9 negatively regulates LDLR-mediated uptake of LTA and LPS by HepG2 hepatocytes through an LDL-dependent mechanism, whereas LRP1 and high-density lipoprotein do not contribute to this uptake pathway. Bacterial lipid uptake by hepatocytes was not associated with cytokine production or hepatocellular injury. In conclusion, our study characterizes an LDL-dependent and LDLR-mediated bacterial lipid uptake pathway regulated by PCSK9, and provides evidence in support of PCSK9 inhibition as a potential therapeutic strategy for sepsis.
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Host defenses against metabolic endotoxaemia and their impact on lipopolysaccharide detection. Int Rev Immunol 2017; 36:125-144. [DOI: 10.1080/08830185.2017.1280483] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Satoh M, Iwahori T, Sugawara N, Yamazaki M. Liver argininosuccinate synthase binds to bacterial lipopolysaccharides and lipid A and inactivates their biological activities. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/09680519060120010301] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The liver is known to clear and detoxify circulating lipopolysaccharide (LPS). To characterize the molecules involved in this process in the liver, we attempted to purify mouse liver protein(s) that can interact with lipid A, a biologically active portion of LPS. By partially purifying the inactivating activity against a synthetic lipid A analog, we observed the enrichment of a 45-kDa protein in the active fractions. The internal amino acid sequences of the protein were identical with those of argininosuccinate synthase (EC 6.3.4.5). To examine whether argininosuccinate synthase can interact with lipid A, we purified the enzyme from mouse liver and found the co-elevation of the specific enzyme activity and specific lipid A-inactivating activity, indicating that argininosuccinate synthase is the major lipid A-interacting protein in liver. Argininosuccinate synthase also inhibited the biological activities (macrophage activation and Limulus test) of natural lipid A and rough-type LPS but not smooth-type LPS. The enzyme activity was inhibited by lipid A and rough-type LPS and also by smooth-type LPS. Native gel electrophoresis of a mixture of argininosuccinate synthase and LPS and immunoprecipitation of a mixture of argininosuccinate synthase and [3H]-LPS with anti-argininosuccinate synthase antiserum showed that argininosuccinate synthase stably bound lipid A and LPS. These findings, together, indicate that argininosuccinate synthase can effectively bind LPS in the liver.
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Affiliation(s)
- Motonobu Satoh
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa, Japan,-u.ac.jp
| | - Tsuguya Iwahori
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa, Japan
| | - Naoki Sugawara
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa, Japan
| | - Masatoshi Yamazaki
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa, Japan
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6
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Xie ZL, Ye PS, Zhang SK, Zhang YS, Shen XZ. Endogenous LPS alters liver GH/IGF system gene expression and plasma lipoprotein lipase in goats. Physiol Res 2015; 64:721-9. [PMID: 25804093 DOI: 10.33549/physiolres.932854] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Endotoxin lipopolysaccharide (LPS) affects the ruminant health and animal performance. The main purposes of this study were to investigate the potential effects of GH/IGF system and lipoprotein lipase (LPL) concentration on resistance the circulating LPS concentration increased in liver with high concentrate diet treatment. Non-lactating goats were randomly allocated to two groups: a high-concentrate diet (HCD) or a low-concentrate diet (LCD) in cross over design and the blood collection at different time points after feeding at the end of the experiment. The average rumen pH was significantly reduced (P<0.05), but the duration with pH was not more than 120 min in the HCD group. The plasma LPL concentration was significantly raised (P<0.05). However, from 2 h onwards, LPS concentration was significantly reduced (P<0.01) in the HCD group compared with LCD group. In addition, the plasma IGF1 concentration and the hepatic insulin-like growth factor-1 receptor (IGF1R) mRNA expression were markedly reduced (P<0.05). However, growth hormone (GH) secretion at 15, 30, and 45 min after feeding and growth hormone receptor (GHR) mRNA expression in the liver was significantly increased (P<0.05) in HCD group. The correlation analysis showed that the plasma LPL concentration was positively correlated with hepatic GHR mRNA expression (P<0.05). Conversely, the plasma LPS concentration was negatively correlated with LPL concentration (P<0.05). These findings reveal that alterations in GH/IGF system function in response to a high-concentrate diet are accompanied by corresponding changes in systemic LPL in non-lactating goats' liver in presence of endogenous LPS stress.
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Affiliation(s)
- Z L Xie
- Key Laboratory of Animal Physiology and Biochemistry, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
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Cationic Nanoemulsions Bearing Ciprofloxacin Surf-Plexes Enhances Its Therapeutic Efficacy in Conditions of E. coli Induced Peritonitis and Sepsis. Pharm Res 2014; 31:2630-42. [DOI: 10.1007/s11095-014-1360-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 03/15/2014] [Indexed: 01/23/2023]
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8
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Deng M, Scott MJ, Loughran P, Gibson G, Sodhi C, Watkins S, Hackam D, Billiar TR. Lipopolysaccharide clearance, bacterial clearance, and systemic inflammatory responses are regulated by cell type-specific functions of TLR4 during sepsis. THE JOURNAL OF IMMUNOLOGY 2013; 190:5152-60. [PMID: 23562812 DOI: 10.4049/jimmunol.1300496] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The morbidity associated with bacterial sepsis is the result of host immune responses to pathogens, which are dependent on pathogen recognition by pattern recognition receptors, such as TLR4. TLR4 is expressed on a range of cell types, yet the mechanisms by which cell-specific functions of TLR4 lead to an integrated sepsis response are poorly understood. To address this, we generated mice in which TLR4 was specifically deleted from myeloid cells (LysMTLR4KO) or hepatocytes (HCTLR4KO) and then determined survival, bacterial counts, host inflammatory responses, and organ injury in a model of cecal ligation and puncture (CLP), with or without antibiotics. LysM-TLR4 was required for phagocytosis and efficient bacterial clearance in the absence of antibiotics. Survival, the magnitude of the systemic and local inflammatory responses, and liver damage were associated with bacterial levels. HCTLR4 was required for efficient LPS clearance from the circulation, and deletion of HCTLR4 was associated with enhanced macrophage phagocytosis, lower bacterial levels, and improved survival in CLP without antibiotics. Antibiotic administration during CLP revealed an important role for hepatocyte LPS clearance in limiting sepsis-induced inflammation and organ injury. Our work defines cell type-selective roles for TLR4 in coordinating complex immune responses to bacterial sepsis and suggests that future strategies for modulating microbial molecule recognition should account for varying roles of pattern recognition receptors in multiple cell populations.
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Affiliation(s)
- Meihong Deng
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA
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Mani V, Weber TE, Baumgard LH, Gabler NK. Growth and Development Symposium: Endotoxin, inflammation, and intestinal function in livestock. J Anim Sci 2012; 90:1452-65. [PMID: 22247110 DOI: 10.2527/jas.2011-4627] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Endotoxin, also referred to as lipopolysaccharide (LPS), can stimulate localized or systemic inflammation via the activation of pattern recognition receptors. Additionally, endotoxin and inflammation can regulate intestinal epithelial function by altering integrity, nutrient transport, and utilization. The gastrointestinal tract is a large reservoir of both gram-positive and gram-negative bacteria, of which the gram-negative bacteria serve as a source of endotoxin. Luminal endotoxin can enter circulation via two routes: 1) nonspecific paracellular transport through epithelial cell tight junctions, and 2) transcellular transport through lipid raft membrane domains involving receptor-mediated endocytosis. Paracellular transport of endotoxin occurs through dissociation of tight junction protein complexes resulting in reduced intestinal barrier integrity, which can be a result of enteric disease, inflammation, or environmental and metabolic stress. Transcellular transport, via specialized membrane regions rich in glycolipids, sphingolipids, cholesterol, and saturated fatty acids, is a result of raft recruitment of endotoxin-related signaling proteins leading to endotoxin signaling and endocytosis. Both transport routes and sensitivity to endotoxin may be altered by diet and environmental and metabolic stresses. Intestinal-derived endotoxin and inflammation result in suppressed appetite, activation of the immune system, and partitioning of energy and nutrients away from growth toward supporting the immune system requirements. In livestock, this leads to the suppression of growth, particularly suppression of lean tissue accretion. In this paper, we summarize the evidence that intestinal transport of endotoxin and the subsequent inflammation leads to decrease in the production performance of agricultural animals and we present an overview of endotoxin detoxification mechanisms in livestock.
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Affiliation(s)
- V Mani
- Department of Animal Science, Iowa State University, Ames 50011, USA
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10
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Burcelin R, Serino M, Chabo C, Blasco-Baque V, Amar J. Gut microbiota and diabetes: from pathogenesis to therapeutic perspective. Acta Diabetol 2011; 48:257-273. [PMID: 21964884 PMCID: PMC3224226 DOI: 10.1007/s00592-011-0333-6] [Citation(s) in RCA: 171] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 09/01/2011] [Indexed: 12/13/2022]
Abstract
More than several hundreds of millions of people will be diabetic and obese over the next decades in front of which the actual therapeutic approaches aim at treating the consequences rather than causes of the impaired metabolism. This strategy is not efficient and new paradigms should be found. The wide analysis of the genome cannot predict or explain more than 10-20% of the disease, whereas changes in feeding and social behavior have certainly a major impact. However, the molecular mechanisms linking environmental factors and genetic susceptibility were so far not envisioned until the recent discovery of a hidden source of genomic diversity, i.e., the metagenome. More than 3 million genes from several hundreds of species constitute our intestinal microbiome. First key experiments have demonstrated that this biome can by itself transfer metabolic disease. The mechanisms are unknown but could be involved in the modulation of energy harvesting capacity by the host as well as the low-grade inflammation and the corresponding immune response on adipose tissue plasticity, hepatic steatosis, insulin resistance and even the secondary cardiovascular events. Secreted bacterial factors reach the circulating blood, and even full bacteria from intestinal microbiota can reach tissues where inflammation is triggered. The last 5 years have demonstrated that intestinal microbiota, at its molecular level, is a causal factor early in the development of the diseases. Nonetheless, much more need to be uncovered in order to identify first, new predictive biomarkers so that preventive strategies based on pre- and probiotics, and second, new therapeutic strategies against the cause rather than the consequence of hyperglycemia and body weight gain.
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Affiliation(s)
- Rémy Burcelin
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR 1048, Toulouse, France.
- Université de Toulouse, UPS, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), 31432, Toulouse cedex 4, France.
| | - Matteo Serino
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR 1048, Toulouse, France
- Université de Toulouse, UPS, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), 31432, Toulouse cedex 4, France
| | - Chantal Chabo
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR 1048, Toulouse, France
- Université de Toulouse, UPS, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), 31432, Toulouse cedex 4, France
| | - Vincent Blasco-Baque
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR 1048, Toulouse, France
- Université de Toulouse, UPS, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), 31432, Toulouse cedex 4, France
| | - Jacques Amar
- Department of Therapeutics, Rangueil Hospital, Toulouse, France
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Miranda-Díaz AG, Alonso-Martínez H, Hernández-Ojeda J, Arias-Carvajal O, Rodríguez-Carrizalez AD, Román-Pintos LM. Toll-like receptors in secondary obstructive cholangiopathy. Gastroenterol Res Pract 2011; 2011:265093. [PMID: 22114589 PMCID: PMC3205723 DOI: 10.1155/2011/265093] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 08/16/2011] [Accepted: 08/22/2011] [Indexed: 12/19/2022] Open
Abstract
Secondary obstructive cholangiopathy is characterized by intra- or extrahepatic bile tract obstruction. Liver inflammation and structural alterations develop due to progressive bile stagnation. Most frequent etiologies are biliary atresia in children, and hepatolithiasis, postcholecystectomy bile duct injury, and biliary primary cirrhosis in adults, which causes chronic biliary cholangitis. Bile ectasia predisposes to multiple pathogens: viral infections in biliary atresia; Gram-positive and/or Gram-negative bacteria cholangitis found in hepatolithiasis and postcholecystectomy bile duct injury. Transmembrane toll-like receptors (TLRs) are activated by virus, bacteria, fungi, and parasite stimuli. Even though TLR-2 and TLR-4 are the most studied receptors related to liver infectious diseases, other TLRs play an important role in response to microorganism damage. Acquired immune response is not vertically transmitted and reflects the infectious diseases history of individuals; in contrast, innate immunity is based on antigen recognition by specific receptors designated as pattern recognition receptors and is transmitted vertically through the germ cells. Understanding the mechanisms for bile duct inflammation is essential for the future development of therapeutic alternatives in order to avoid immune-mediated destruction on secondary obstructive cholangiopathy. The role of TLRs in biliary atresia, hepatolithiasis, bile duct injury, and primary biliary cirrhosis is described in this paper.
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Affiliation(s)
- A. G. Miranda-Díaz
- Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, 44340 JAL, Mexico
| | - H. Alonso-Martínez
- Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, 44340 JAL, Mexico
| | - J. Hernández-Ojeda
- Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, 44340 JAL, Mexico
| | - O. Arias-Carvajal
- Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, 44340 JAL, Mexico
| | - A. D. Rodríguez-Carrizalez
- Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, 44340 JAL, Mexico
| | - L. M. Román-Pintos
- Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, 44340 JAL, Mexico
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Abstract
Chronic inflammation is highly prevalent in patients with chronic kidney disease (CKD), and is associated with increased cardiovascular morbidity and mortality. There are numerous causes of inflammation in CKD, including the potential exposure to bacterial lipopolysaccharide (LPS) in the bloodstream from the intestinal tract as a result of uremia-related increases in intestinal permeability. Sevelamer, a commonly prescribed non-calcium, non-metal-based phosphate binder in CKD, also possesses putative anti-inflammatory properties, as its use has been associated with a reduction in systemic markers of inflammation. Emerging studies have provided direct evidence that sevelamer shows in vitro LPS-binding properties. Indirect clinical evidence suggests that sevelamer might also limit translocation of LPS from the intestinal lumen into the bloodstream. This review focuses on bacterial LPS as a source of chronic inflammation in CKD, and proposes that sevelamer might possess novel anti-inflammatory properties as a result of LPS binding in the intestinal tract. The proposed hypothesis that intestinal LPS-binding by sevelamer may lower circulating LPS, and in turn systemic inflammation, requires further evaluation in a clinical trial.
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Satoh M, Ando S, Shinoda T, Yamazaki M. Clearance of bacterial lipopolysaccharides and lipid A by the liver and the role of argininosuccinate synthase. Innate Immun 2008; 14:51-60. [PMID: 18387919 DOI: 10.1177/1753425907087267] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The liver is thought to be involved in the systemic clearance and detoxification of lipopolysaccharide (LPS). Argininosuccinate synthase (AS), a liver cytosolic urea cycle enzyme, has been found to bind to and inactivate LPS and lipid A. To elucidate the participation of AS in the clearance of LPS by liver and hepatocytes, we investigated the correlation between AS content and the removal of lipid A and LPS in vivo and in vitro, tracing levels of biological activity. A hepatotoxic model in which mice were injected with CCl(4) revealed a significant reduction in lipid A clearance along with liver failure on day 1; total body clearance was changed to 0.534 ml/min from 1.42 ml/min. AS content in liver concomitantly decreased to about half and AS leaked to blood at about 6 microg/ml. Total body clearance of i.v. injected AS was estimated at 0.083 ml/min, which predicted about 24-h leakage of AS after CCl(4) injection. The treatment also reduced the clearance of R-type LPSs to a lesser degree the larger its polysaccharide portion. S-type LPS, which has a large O-antigen polysaccharide, exhibited enhancement of clearance on CCl(4) treatment. When pretreated in vitro with AS and injected into normal mice, lipid A and R-type LPS showed a similar pattern of clearance of residual activities to the untreated forms, but S-type LPS exhibited enhancement of clearance. Comparison between different strains of mice revealed a correlation of AS content in liver and lipid A clearance, where the higher AS strain C3H/He mice showed a more rapid clearance than the lower AS strains C57BL/6 and BALB/c. Primary spheroid cultures of hepatocytes treated with 0.1 microM dexamethasone and 1 microM glucagon showed about a 2-fold increase in AS amount and a more rapid clearance of LPS from culture medium than untreated cells. These results suggest that AS in hepatocytes may be involved in the process of lipid A and LPS clearance and the extracellular leakage of AS may also participate in the systemic detoxification.
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Affiliation(s)
- Motonobu Satoh
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamihara, Kanagawa, Japan.
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14
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Huang H, Liu T, Rose JL, Stevens RL, Hoyt DG. Sensitivity of mice to lipopolysaccharide is increased by a high saturated fat and cholesterol diet. JOURNAL OF INFLAMMATION-LONDON 2007; 4:22. [PMID: 17997851 PMCID: PMC2186306 DOI: 10.1186/1476-9255-4-22] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Accepted: 11/12/2007] [Indexed: 11/16/2022]
Abstract
Background It was hypothesized that a pro-atherogenic, high saturated fat and cholesterol diet (HCD) would increase the inflammatory response to E. coli endotoxin (LPS) and increase its concentration in plasma after administration to mice. Methods C57Bl/6 mice were fed a HCD or a control diet (CD) for 4 weeks, and then treated with saline, 0.5, 1 or 2 mg LPS/kg, ip. Liver injury (alanine:2-oxoglutarate aminotransferase and aspartate aminotransferase, collagen staining), circulating cytokines (tumor necrosis factor-α, interleukin-6 and interferon-γ), factors that can bind LPS (serum amyloid A, apolipoprotein A1, LPS binding protein, and CD14), and plasma levels of LPS were measured. The hepatic response was assessed by measuring vascular cell adhesion molecule (VCAM)-1, inducible nitric oxide synthase (iNOS) and signal transducer and activator of transcription-1 proteins, and VCAM-1 and iNOS mRNAs. Hepatic mRNA encoding the LPS receptor, Toll like receptor 4, was also determined. Results Two mg LPS/kg killed 100% of mice fed HCD within 5 d, while no mice fed CD died. All mice treated with 0 to 1 mg LPS/kg survived 24 h. HCD increased plasma alanine:2-oxoglutarate aminotransferase and aspartate aminotransferase, and the enzymes were increased more by LPS in HCD than CD mice. Induction of plasma tumor necrosis factor-α, interleukin-6, and interferon-γ by LPS was greater with HCD than CD. Hepatic VCAM-1 and iNOS protein and mRNA were induced by LPS more in mice fed HCD than CD. Tyrosine phosphorylation of signal transducer and activator of transcription-1 caused by LPS was prolonged in HCD compared with CD mice. Despite the hepatic effects of HCD, diet had no effect on the LPS plasma concentration-time profile. HCD alone did not affect circulating levels of plasma apolipoprotein A1 or LPS binding protein. However, plasma concentrations of serum amyloid A and CD14, and hepatic toll-like receptor-4 mRNA were increased in mice fed HCD. Conclusion HCD increased the sensitivity of mice to LPS without affecting its plasma level. Although increased serum amyloid A and CD14 in the circulation may inhibit LPS actions, their overexpression, along with hepatic toll-like receptor-4 or other factors, may contribute to the heightened sensitivity to LPS.
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Affiliation(s)
- Hong Huang
- Division of Pharmacology, The Ohio State University College of Pharmacy, Columbus, OH, 43210, USA.
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Abstract
Pattern recognition receptors (PRRs) function as sensors of microbial danger signals enabling the vertebrate host to initiate an immune response. PRRs are present not only in immune cells but also in liver parenchymal cells and the complexity of the cell populations provide unique aspects to pathogen recognition and tissue damage in the liver. This review discusses the role of different PRRs in pathogen recognition in the liver, and focuses on the role of PRRs in hepatic inflammation, cholestasis, ischemia, repair and fibrosis. PRRs as novel therapeutic targets are evaluated.
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Affiliation(s)
- Gyongyi Szabo
- Liver Center, Division of Gastroenterology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
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Kasravi FB, Brecht WJ, Weisgraber KH, Harris HW. Induction of cytokine tolerance requires internalization of Chylomicron-Bound LPS into hepatocytes. J Surg Res 2003; 115:303-9. [PMID: 14697298 DOI: 10.1016/s0022-4804(03)00197-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
BACKGROUND Chylomicron-bound LPS (CM-LPS) renders hepatocytes unresponsive to stimulation by proinflammatory cytokines, a process termed cytokine tolerance. We have shown that cytokine tolerance is a time- and dose-dependent process requiring functional low-density lipoprotein receptors (LDLR). Thus, we hypothesized that cytokine tolerance directly correlates with the internalization of CM-LPS complexes, and inhibition of lipoprotein binding and/or internalization inhibits the induction of cytokine tolerance in hepatocytes. MATERIALS AND METHODS We correlated the rate of internalization of radioiodinated CM-LPS complexes with hepatocellular NO production as a measure of cytokine responsiveness. In additional studies, we used four different strategies to inhibit binding/internalization of CM-LPS via LDLR and then determined the effect of each strategy on the induction of cytokine tolerance. RESULTS There was a strong inverse correlation between the internalization of CM-LPS and the responsiveness of hepatocytes to proinflammatory cytokines (r(2) = -0.997). Furthermore, the greater the degree of LDLR inhibition, the less susceptible hepatocytes were to the induction of cytokine tolerance by CM-bound LPS. Accordingly, cytokine tolerance induction was inhibited in hepatocytes with decreased membrane expression of LDLR as compared to control cells (69 versus 12% control; P = 0.005). Competitive inhibition of CM-LPS binding prevented internalization of CM-LPS and resulted in loss of the cytokine-tolerant phenotype. Whereas CM-LPS successfully induced cytokine tolerance in ldlr(-/-) hepatocytes, it only occurred after a prolonged pretreatment period of 8 h. CM-LPS complexes containing apolipoprotein (apo) E(2) also required a prolonged pretreatment period to induce a level of cytokine tolerance comparable to that induced by CM-LPS complexes containing either apo E(3) or E(4). CONCLUSION Lipoprotein-bound LPS inhibits the responsiveness of hepatocytes to proinflammatory cytokines in a manner directly correlated with the internalization of LPS. Furthermore, inhibition of lipoprotein binding/internalization prevents this LPS-mediated induction of cytokine tolerance in rodent hepatocytes.
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Affiliation(s)
- F Behzad Kasravi
- UCSF Surgical Research Laboratory, San Francisco General Hospital, San Francisco, CA 94110, USA
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Kitchens RL, Thompson PA, Munford RS, O'Keefe GE. Acute inflammation and infection maintain circulating phospholipid levels and enhance lipopolysaccharide binding to plasma lipoproteins. J Lipid Res 2003; 44:2339-48. [PMID: 12923224 DOI: 10.1194/jlr.m300228-jlr200] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Circulating lipoproteins are thought to play an important role in the detoxification of lipopolysaccharide (LPS) by binding the bioactive lipid A portion of LPS to the lipoprotein surface. It has been assumed that hypocholesterolemia contributes to inflammation during critical illness by impairing LPS neutralization. We tested whether critical illness impaired LPS binding to lipoproteins and found, to the contrary, that LPS binding was enhanced and that LPS binding to the lipoprotein classes correlated with their phospholipid content. Whereas low serum cholesterol was almost entirely due to the loss of esterified cholesterol (a lipoprotein core component), phospholipids (the major lipoprotein surface lipid) were maintained at near normal levels and were increased in a hypertriglyceridemic subset of septic patients. The levels of phospholipids found in the LDL and VLDL fractions varied inversely with those in the HDL fraction, and LPS bound predominantly to lipoproteins in the LDL and VLDL fractions when HDL levels were low. Lipoproteins isolated from the serum of septic patients neutralized the bioactivity of the LPS that had bound to them. Our results show that the host response to acute inflammation and infection tends to maintain lipoprotein phospholipid levels and that, despite hypocholesterolemia and reduced HDL levels, circulating lipoproteins maintain their ability to bind and neutralize an important bacterial agonist, LPS.
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Affiliation(s)
- Richard L Kitchens
- Departments of Internal Medicine, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9113, USA.
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Vreugdenhil ACE, Rousseau CH, Hartung T, Greve JWM, van 't Veer C, Buurman WA. Lipopolysaccharide (LPS)-binding protein mediates LPS detoxification by chylomicrons. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:1399-405. [PMID: 12538700 DOI: 10.4049/jimmunol.170.3.1399] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Chylomicrons have been shown to protect against endotoxin-induced lethality. LPS-binding protein (LBP) is involved in the inactivation of bacterial toxin by lipoproteins. The current study examined the interaction among LBP, chylomicrons, and bacterial toxin. LBP was demonstrated to associate with chylomicrons and enhance the amount of LPS binding to chylomicrons in a dose-dependent fashion. In addition, LBP accelerated LPS binding to chylomicrons. This LBP-induced interaction of LPS with chylomicrons prevented endotoxin toxicity, as demonstrated by reduced cytokine secretion by PBMC. When postprandial circulating concentrations of chylomicrons were compared with circulating levels of low density lipoprotein, very low density lipoprotein, and high density lipoprotein, chylomicrons exceeded the other lipoproteins in LPS-inactivating capacity. Furthermore, highly purified lipoteichoic acid, an immunostimulatory component of Gram-positive bacteria, was detoxified by incubation with LBP and chylomicrons. In conclusion, our results indicate that LBP associates with chylomicrons and enables chylomicrons to rapidly bind bacterial toxin, thereby preventing cell activation. Besides a role in the detoxification of bacterial toxin present in the circulation, we believe that LBP-chylomicron complexes may be part of a local defense mechanism of the intestine against translocated bacterial toxin.
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Affiliation(s)
- Anita C E Vreugdenhil
- Nutrition and Toxicology Research Institute Maastricht, Department of General Surgery, Maastricht University, Maastricht, The Netherlands
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