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Granja TF, Köhler D, Leiss V, Eggstein C, Nürnberg B, Rosenberger P, Beer-Hammer S. Platelets and the Cybernetic Regulation of Ischemic Inflammatory Responses through PNC Formation Regulated by Extracellular Nucleotide Metabolism and Signaling. Cells 2022; 11:cells11193009. [PMID: 36230973 PMCID: PMC9561997 DOI: 10.3390/cells11193009] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 09/12/2022] [Accepted: 09/20/2022] [Indexed: 11/16/2022] Open
Abstract
Ischemic events are associated with severe inflammation and are here referred to as ischemic inflammatory response (IIR). Recent studies identified the formation of platelet–neutrophil complexes (PNC) as key players in IIR. We investigated the role of extracellular platelet nucleotide signaling in the context of IIR and defined a cybernetic circle, including description of feedback loops. Cybernetic circles seek to integrate different levels of information to understand how biological systems function. Our study specifies the components of the cybernetic system of platelets in IIR and describes the theoretical progression of IIR passing the cybernetic cycle with positive and negative feedback loops based on nucleotide-dependent signaling and functional regulation. The cybernetic components and feedback loops were explored by cytometry, immunohistological staining, functional blocking antibodies, and ADP/ATP measurements. Using several ex vivo and in vivo approaches we confirmed cybernetic parameters, such as controller, sensor, and effector (VASP phosphorylation, P2Y12, ADORAs and GPIIb/IIIa activity), as well as set points (ADP, adenosine) and interfering control and disturbance variables (ischemia). We demonstrate the impact of the regulated platelet–neutrophil complex (PNC) formation in blood and the resulting damage to the affected inflamed tissue. Taken together, extracellular nucleotide signaling, PNC formation, and tissue damage in IIR can be integrated in a controlled cybernetic circle of platelet function, as introduced through this study.
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Affiliation(s)
- Tiago F. Granja
- Lusófona’s Research Center for Biosciences & Health Technologies, CBIOS–Universidade, Campo Grande 376, 1749-024 Lisboa, Portugal
- Department of Anesthesiology and Intensive Care Medicine, Tübingen University Hospital, Wilhelmstrasse 56, D-72074 Tübingen, Germany
| | - David Köhler
- Department of Anesthesiology and Intensive Care Medicine, Tübingen University Hospital, Wilhelmstrasse 56, D-72074 Tübingen, Germany
| | - Veronika Leiss
- Department of Pharmacology and Experimental Therapy and Toxicology and Interfaculty Center of Pharmacogenomics and Drug Research (ICePhA), Tübingen University Hospital, Wilhelmstrasse 56, D-72074 Tübingen, Germany
| | - Claudia Eggstein
- Department of Anesthesiology and Intensive Care Medicine, Tübingen University Hospital, Wilhelmstrasse 56, D-72074 Tübingen, Germany
| | - Bernd Nürnberg
- Department of Pharmacology and Experimental Therapy and Toxicology and Interfaculty Center of Pharmacogenomics and Drug Research (ICePhA), Tübingen University Hospital, Wilhelmstrasse 56, D-72074 Tübingen, Germany
| | - Peter Rosenberger
- Department of Anesthesiology and Intensive Care Medicine, Tübingen University Hospital, Wilhelmstrasse 56, D-72074 Tübingen, Germany
| | - Sandra Beer-Hammer
- Department of Pharmacology and Experimental Therapy and Toxicology and Interfaculty Center of Pharmacogenomics and Drug Research (ICePhA), Tübingen University Hospital, Wilhelmstrasse 56, D-72074 Tübingen, Germany
- Correspondence: ; Tel.: +49-7071-29-74594
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Yuan X, Mills T, Doursout MF, Evans SE, Vidal Melo MF, Eltzschig HK. Alternative adenosine Receptor activation: The netrin-Adora2b link. Front Pharmacol 2022; 13:944994. [PMID: 35910389 PMCID: PMC9334855 DOI: 10.3389/fphar.2022.944994] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 06/28/2022] [Indexed: 11/25/2022] Open
Abstract
During hypoxia or inflammation, extracellular adenosine levels are elevated. Studies using pharmacologic approaches or genetic animal models pertinent to extracellular adenosine signaling implicate this pathway in attenuating hypoxia-associated inflammation. There are four distinct adenosine receptors. Of these, it is not surprising that the Adora2b adenosine receptor functions as an endogenous feedback loop to control hypoxia-associated inflammation. First, Adora2b activation requires higher adenosine concentrations compared to other adenosine receptors, similar to those achieved during hypoxic inflammation. Second, Adora2b is transcriptionally induced during hypoxia or inflammation by hypoxia-inducible transcription factor HIF1A. Studies seeking an alternative adenosine receptor activation mechanism have linked netrin-1 with Adora2b. Netrin-1 was originally discovered as a neuronal guidance molecule but also functions as an immune-modulatory signaling molecule. Similar to Adora2b, netrin-1 is induced by HIF1A, and has been shown to enhance Adora2b signaling. Studies of acute respiratory distress syndrome (ARDS), intestinal inflammation, myocardial or hepatic ischemia and reperfusion implicate the netrin-Adora2b link in tissue protection. In this review, we will discuss the potential molecular linkage between netrin-1 and Adora2b, and explore studies demonstrating interactions between netrin-1 and Adora2b in attenuating tissue inflammation.
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Affiliation(s)
- Xiaoyi Yuan
- Department of Anesthesiology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Tingting Mills
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Marie-Francoise Doursout
- Department of Anesthesiology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Scott E. Evans
- Department of Pulmonology, MD Anderson Cancer Center, Houston, TX, United States
| | | | - Holger K. Eltzschig
- Department of Anesthesiology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
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Đurašević S, Stojković M, Sopta J, Pavlović S, Borković-Mitić S, Ivanović A, Jasnić N, Tosti T, Đurović S, Đorđević J, Todorović Z. The effects of meldonium on the acute ischemia/reperfusion liver injury in rats. Sci Rep 2021; 11:1305. [PMID: 33446709 PMCID: PMC7809046 DOI: 10.1038/s41598-020-80011-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 12/16/2020] [Indexed: 01/18/2023] Open
Abstract
Acute ischemia/reperfusion (I/R) liver injury is a clinical condition challenging to treat. Meldonium is an anti-ischemic agent that shifts energy production from fatty acid oxidation to less oxygen-consuming glycolysis. Thus, we investigated the effects of a 4-week meldonium pre-treatment (300 mg/kg b.m./day) on the acute I/R liver injury in Wistar strain male rats. Our results showed that meldonium ameliorates I/R-induced liver inflammation and injury, as confirmed by liver histology, and by attenuation of serum alanine- and aspartate aminotransferase activity, serum and liver high mobility group box 1 protein expression, and liver expression of Bax/Bcl2, haptoglobin, and the phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells. Through the increased hepatic activation of the nuclear factor erythroid 2-related factor 2, meldonium improves the antioxidative defence in the liver of animals subjected to I/R, as proved by an increase in serum and liver ascorbic/dehydroascorbic acid ratio, hepatic haem oxygenase 1 expression, glutathione and free thiol groups content, and hepatic copper-zinc superoxide dismutase, manganese superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activity. Based on our results, it can be concluded that meldonium represent a protective agent against I/R-induced liver injury, with a clinical significance in surgical procedures.
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Affiliation(s)
- Siniša Đurašević
- Faculty of Biology, University of Belgrade, 16 Studentski Trg, 11000, Belgrade, Republic of Serbia.
| | - Maja Stojković
- Faculty of Medicine, University of Belgrade, Belgrade, Republic of Serbia
| | - Jelena Sopta
- Faculty of Medicine, University of Belgrade, Belgrade, Republic of Serbia
| | - Slađan Pavlović
- Institute for Biological Research "Siniša Stanković" - National Institute of Republic of Serbia, University of Belgrade, Belgrade, Republic of Serbia
| | - Slavica Borković-Mitić
- Institute for Biological Research "Siniša Stanković" - National Institute of Republic of Serbia, University of Belgrade, Belgrade, Republic of Serbia
| | - Anđelija Ivanović
- Institute for Biological Research "Siniša Stanković" - National Institute of Republic of Serbia, University of Belgrade, Belgrade, Republic of Serbia
| | - Nebojša Jasnić
- Faculty of Biology, University of Belgrade, 16 Studentski Trg, 11000, Belgrade, Republic of Serbia
| | - Tomislav Tosti
- Faculty of Chemistry, University of Belgrade, Belgrade, Republic of Serbia
| | - Saša Đurović
- Institute of General and Physical Chemistry, University of Belgrade, Belgrade, Republic of Serbia
| | - Jelena Đorđević
- Faculty of Biology, University of Belgrade, 16 Studentski Trg, 11000, Belgrade, Republic of Serbia
| | - Zoran Todorović
- Faculty of Medicine, University of Belgrade, Belgrade, Republic of Serbia.,University Medical Centre "Bežanijska Kosa", University of Belgrade, Belgrade, Republic of Serbia
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Koh WU, Kim J, Lee J, Song GW, Hwang GS, Tak E, Song JG. Remote Ischemic Preconditioning and Diazoxide Protect from Hepatic Ischemic Reperfusion Injury by Inhibiting HMGB1-Induced TLR4/MyD88/NF-κB Signaling. Int J Mol Sci 2019; 20:ijms20235899. [PMID: 31771292 PMCID: PMC6929132 DOI: 10.3390/ijms20235899] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 11/17/2019] [Accepted: 11/20/2019] [Indexed: 01/23/2023] Open
Abstract
Remote ischemic preconditioning (RIPC) is known to have a protective effect against hepatic ischemia-reperfusion (IR) injury in animal models. However, the underlying mechanism of action is not clearly understood. This study examined the effectiveness of RIPC in a mouse model of hepatic IR and aimed to clarify the mechanism and relationship of the ATP-sensitive potassium channel (KATP) and HMGB1-induced TLR4/MyD88/NF-κB signaling. C57BL/6 male mice were separated into six groups: (i) sham-operated control, (ii) IR, (iii) RIPC+IR, (iv) RIPC+IR+glyburide (KATP blocker), (v) RIPC+IR+diazoxide (KATP opener), and (vi) RIPC+IR+diazoxide+glyburide groups. Histological changes, including hepatic ischemia injury, were assessed. The levels of circulating liver enzymes and inflammatory cytokines were measured. Levels of apoptotic proteins, proinflammatory factors (TLR4, HMGB1, MyD88, and NF-κB), and IκBα were measured by Western blot and mRNA levels of proinflammatory cytokine factors were determined by RT-PCR. RIPC significantly decreased hepatic ischemic injury, inflammatory cytokine levels, and liver enzymes compared to the corresponding values observed in the IR mouse model. The KATP opener diazoxide + RIPC significantly reduced hepatic IR injury demonstrating an additive effect on protection against hepatic IR injury. The protective effect appeared to be related to the opening of KATP, which inhibited HMGB1-induced TRL4/MyD88/NF-kB signaling.
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Affiliation(s)
- Won Uk Koh
- Department of Anesthesiology, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea; (W.U.K.); (G.S.H.)
| | - Jiye Kim
- Asan Institute for Life Sciences and Asan-Minnesota Institute for Innovating Transplantation, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea; (J.K.); (J.L.)
| | - Jooyoung Lee
- Asan Institute for Life Sciences and Asan-Minnesota Institute for Innovating Transplantation, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea; (J.K.); (J.L.)
| | - Gi-Won Song
- Division of Liver Transplantation and Hepatobiliary Surgery, Asan-Minnesota Institute for Innovating Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea;
| | - Gyu Sam Hwang
- Department of Anesthesiology, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea; (W.U.K.); (G.S.H.)
| | - Eunyoung Tak
- Asan Institute for Life Sciences and Asan-Minnesota Institute for Innovating Transplantation, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea; (J.K.); (J.L.)
- Correspondence: (E.T.); (J.-G.S.); Tel.: +82-2-3010-4634 (E.T.); Tel.: +82-2-3010-3869 (J.-G.S.)
| | - Jun-Gol Song
- Department of Anesthesiology, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea; (W.U.K.); (G.S.H.)
- Correspondence: (E.T.); (J.-G.S.); Tel.: +82-2-3010-4634 (E.T.); Tel.: +82-2-3010-3869 (J.-G.S.)
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Adenosine Receptor Adora2b Plays a Mechanistic Role in the Protective Effect of the Volatile Anesthetic Sevoflurane during Liver Ischemia/Reperfusion. Anesthesiology 2016; 125:547-60. [DOI: 10.1097/aln.0000000000001234] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Abstract
Background
Liver ischemia/reperfusion (IR) injury is characterized by hepatic tissue damage and an inflammatory response. This is accompanied by the formation and vascular sequestration of platelet–neutrophil conjugates (PNCs). Signaling through Adora2b adenosine receptors can provide liver protection. Volatile anesthetics may interact with adenosine receptors. This study investigates potential antiinflammatory effects of the volatile anesthetic sevoflurane during liver IR.
Methods
Experiments were performed ex vivo with human blood and in a liver IR model with wild-type, Adora2a−/−, and Adora2b−/− mice. The effect of sevoflurane on platelet activation, PNC formation and sequestration, cytokine release, and liver damage (alanine aminotransferase release) was analyzed using flow cytometry, luminometry, and immunofluorescence. Adenosine receptor expression in liver tissue was analyzed using immunohistochemistry and real-time polymerase chain reaction.
Results
Ex vivo experiments indicate that sevoflurane inhibits platelet and leukocyte activation (n = 5). During liver IR, sevoflurane (2 Vol%) decreased PNC formation 2.4-fold in wild-type (P < 0.05) but not in Adora2b−/− mice (n ≥ 5). Sevoflurane reduced PNC sequestration 1.9-fold (P < 0.05) and alanine aminotransferase release 3.5-fold (P < 0.05) in wild-type but not in Adora2b−/− mice (n = 5). In Adora2a−/− mice, sevoflurane also inhibited PNC formation and cytokine release. Sevoflurane diminished cytokine release (n ≥ 3) and increased Adora2b transcription and expression in liver tissue of wild-types (n = 4).
Conclusions
Our experiments highlight antiinflammatory and tissue-protective properties of sevoflurane during liver IR and reveal a mechanistic role of Adora2b in sevoflurane-associated effects. The targeted use of sevoflurane not only as an anesthetic but also to prevent IR damage is a promising approach in the treatment of critically ill patients.
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7
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Knudsen AR, Andersen KJ, Hamilton-Dutoit S, Nyengaard JR, Mortensen FV. Correlation between liver cell necrosis and circulating alanine aminotransferase after ischaemia/reperfusion injuries in the rat liver. Int J Exp Pathol 2016; 97:133-8. [PMID: 27292534 DOI: 10.1111/iep.12188] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 03/14/2016] [Indexed: 12/11/2022] Open
Abstract
Circulating liver enzymes such as alanine transaminase are often used as markers of hepatocellular damage. Ischaemia/reperfusion (I/R) injury is an inevitable consequence of prolonged liver ischaemia. The aim of this study was to examine the correlation between liver enzymes and volume of liver cell necrosis after ischaemia/reperfusion injuries, using design-unbiased stereological methods. Forty-seven male Wistar rats were subjected to 1 h of partial liver ischaemia, followed by either 4 or 24 h of reperfusion. Within each group, one-third of animals were subjected to ischaemic preconditioning and one-third to ischaemic postconditioning. At the end of reperfusion, blood and liver samples were collected for analysis. The volume of necrotic liver tissue was subsequently correlated to circulating markers of I/R injury. Correlation between histological findings and circulating markers was performed using Pearson's correlation coefficient. Alanine transferase peaked after 4 h of reperfusion; however, at this time-point, only mild necrosis was observed, with a Pearson's correlation coefficient of 0.663 (P = 0.001). After 24 h of reperfusion, alanine aminotransferase was found to be highly correlated to the degree of hepatocellular necrosis R = 0.836 (P = 0.000). Furthermore, alkaline phosphatase (R = 0.806) and α-2-macroglobulin (R = 0.655) levels were also correlated with the degree of necrosis. We show for the first time that there is a close correlation between the volume of hepatocellular necrosis and alanine aminotransferase levels in a model of I/R injury. This is especially apparent after 24 h of reperfusion. Similarly, increased levels of alkaline phosphatase and α-2-macroglobulin are correlated to the volume of liver necrosis.
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Affiliation(s)
- Anders R Knudsen
- Department of Surgical Gastroenterology L, Aarhus University Hospital, Aarhus, Denmark
| | - Kasper J Andersen
- Department of Surgical Gastroenterology L, Aarhus University Hospital, Aarhus, Denmark
| | | | - Jens R Nyengaard
- Stereology & Electron Microscopy Laboratory, Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University Hospital, Aarhus, Denmark
| | - Frank V Mortensen
- Department of Surgical Gastroenterology L, Aarhus University Hospital, Aarhus, Denmark
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Zimmerman MA, Tak E, Ehrentraut SF, Kaplan M, Giebler A, Weng T, Choi DS, Blackburn MR, Kam I, Eltzschig HK, Grenz A. Equilibrative nucleoside transporter (ENT)-1-dependent elevation of extracellular adenosine protects the liver during ischemia and reperfusion. Hepatology 2013; 58:1766-78. [PMID: 23703920 PMCID: PMC3795856 DOI: 10.1002/hep.26505] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 04/10/2013] [Accepted: 04/26/2013] [Indexed: 12/30/2022]
Abstract
UNLABELLED Ischemia and reperfusion-elicited tissue injury contributes to morbidity and mortality of hepatic surgery and during liver transplantation. Previous studies implicated extracellular adenosine signaling in liver protection. Based on the notion that extracellular adenosine signaling is terminated by uptake from the extracellular towards the intracellular compartment by way of equilibrative nucleoside transporters (ENTs), we hypothesized a functional role of ENTs in liver protection from ischemia. During orthotopic liver transplantation in humans, we observed higher expressional levels of ENT1 than ENT2, in conjunction with repression of ENT1 and ENT2 transcript and protein levels following warm ischemia and reperfusion. Treatment with the pharmacologic ENT inhibitor dipyridamole revealed elevations of hepatic adenosine levels and robust liver protection in a murine model of liver ischemia and reperfusion. Studies in gene-targeted mice for Ent1 or Ent2 demonstrated selective protection from liver injury in Ent1(-/-) mice. Treatment with selective adenosine receptor antagonists indicated a contribution of Adora2b receptor signaling in ENT-dependent liver protection. CONCLUSION These findings implicate ENT1 in liver protection from ischemia and reperfusion injury and suggest ENT inhibitors may be of benefit in the prevention or treatment of ischemic liver injury.
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Affiliation(s)
| | - Eunyoung Tak
- Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado
| | | | - Maria Kaplan
- Division of Transplant Surgery, Department of Surgery, University of Colorado
| | - Antasia Giebler
- Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado
| | - Tingting Weng
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Texas, Houston, Texas, USA
| | - Doo-Sup Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Michael R. Blackburn
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Texas, Houston, Texas, USA
| | - Igal Kam
- Division of Transplant Surgery, Department of Surgery, University of Colorado
| | - Holger K. Eltzschig
- Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado
| | - Almut Grenz
- Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado
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Signaling through hepatocellular A2B adenosine receptors dampens ischemia and reperfusion injury of the liver. Proc Natl Acad Sci U S A 2013; 110:12012-7. [PMID: 23812746 DOI: 10.1073/pnas.1221733110] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Ischemia and reperfusion significantly contributes to the morbidity and mortality of liver surgery and transplantation. Based on studies showing a critical role for adenosine signaling in mediating tissue adaptation during hypoxia, we hypothesized that signaling events through adenosine receptors (ADORA1, ADORA2A, ADORA2B, or ADORA3) attenuates hepatic ischemia and reperfusion injury. Initial screening studies of human liver biopsies obtained during hepatic transplantation demonstrated a selective and robust induction of ADORA2B transcript and protein following ischemia and reperfusion. Subsequent exposure of gene-targeted mice for each individual adenosine receptor to liver ischemia and reperfusion revealed a selective role for the Adora2b in liver protection. Moreover, treatment of wild-type mice with an Adora2b-selective antagonist resulted in enhanced liver injury, whereas Adora2b-agonist treatment was associated with attenuated hepatic injury in wild-type, but not in Adora2b(-/-) mice. Subsequent studies in mice with Adora2b deletion in different tissues--including vascular endothelia, myeloid cells, and hepatocytes--revealed a surprising role for hepatocellular-specific Adora2b signaling in attenuating nuclear factor NF-κB activation and thereby mediating liver protection from ischemia and reperfusion injury. These studies provide a unique role for hepatocellular-specific Adora2b signaling in liver protection during ischemia and reperfusion injury.
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Eltzschig HK, Bonney SK, Eckle T. Attenuating myocardial ischemia by targeting A2B adenosine receptors. Trends Mol Med 2013; 19:345-54. [PMID: 23540714 DOI: 10.1016/j.molmed.2013.02.005] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 02/12/2013] [Accepted: 02/20/2013] [Indexed: 02/06/2023]
Abstract
Myocardial ischemia is associated with profound tissue hypoxia due to an imbalance in oxygen supply and demand, and studies of hypoxia-elicited adaptive responses during myocardial ischemia revealed a cardioprotective role for the signaling molecule adenosine. In ischemic human hearts, the A2B adenosine receptor (ADORA2B) is selectively induced. Functional studies in genetic models show that ADORA2B signaling attenuates myocardial infarction by adapting metabolism towards more oxygen efficient utilization of carbohydrates. This adenosine-mediated cardio-adaptive response involves the transcription factor hypoxia-inducible factor HIF1α and the circadian rhythm protein PER2. In this article, we discuss advances in the understanding of adenosine-elicited cardioprotection with particular emphasis on ADORA2B, its downstream targets, and the implications for novel strategies to prevent or treat myocardial ischemia.
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Affiliation(s)
- Holger K Eltzschig
- Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado School of Medicine, Aurora, CO, USA.
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Poth JM, Brodsky K, Ehrentraut H, Grenz A, Eltzschig HK. Transcriptional control of adenosine signaling by hypoxia-inducible transcription factors during ischemic or inflammatory disease. J Mol Med (Berl) 2013; 91:183-93. [PMID: 23263788 PMCID: PMC3560301 DOI: 10.1007/s00109-012-0988-7] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Revised: 11/30/2012] [Accepted: 12/04/2012] [Indexed: 02/08/2023]
Abstract
Inflammatory lesions, ischemic tissues, or solid tumors are characterized by the occurrence of severe tissue hypoxia within the diseased tissue. Subsequent stabilization of hypoxia-inducible transcription factors-particularly of hypoxia-inducible factor 1α (HIF1A)--results in significant alterations of gene expression of resident cells or inflammatory cells that have been recruited into such lesions. Interestingly, studies of hypoxia-induced changes of gene expression identified a transcriptional program that promotes extracellular adenosine signaling. Adenosine is a signaling molecule that functions through the activation of four distinct adenosine receptors--the ADORA1, ADORA2A, ADORA2B, and ADORA3 receptors. Extracellular adenosine is predominantly derived from the phosphohydrolysis of precursor nucleotides, such as adenosine triphosphate or adenosine monophosphate. HIF1A-elicited alterations in gene expression enhance the enzymatic capacity within inflamed tissues to produce extracellular adenosine. Moreover, hypoxia-elicited induction of adenosine receptors--particularly of ADORA2B--results in increased signal transduction. Functional studies in genetic models for HIF1A or adenosine receptors implicate this pathway in an endogenous feedback loop that dampens excessive inflammation and promotes injury resolution, while at the same time enhancing ischemia tolerance. Therefore, pharmacological strategies to enhance HIF-elicited adenosine production or to promote adenosine signaling through adenosine receptors are being investigated for the treatment of acute inflammatory or ischemic diseases characterized by tissue hypoxia.
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Affiliation(s)
- Jens M. Poth
- Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado School of Medicine, Aurora, USA
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Bonn, Germany
| | - Kelley Brodsky
- Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado School of Medicine, Aurora, USA
| | - Heidi Ehrentraut
- Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado School of Medicine, Aurora, USA
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Bonn, Germany
| | - Almut Grenz
- Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado School of Medicine, Aurora, USA
| | - Holger K. Eltzschig
- Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado School of Medicine, Aurora, USA
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Zimmerman M, Tak E, Kaplan M, Mandell MS, Eltzschig HK, Grenz A. Use of a hanging-weight system for liver ischemia in mice. J Vis Exp 2012:e2550. [PMID: 22895458 PMCID: PMC3486745 DOI: 10.3791/2550] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Acute liver injury due to ischemia can occur during several clinical procedures e.g. liver transplantation, hepatic tumor resection or trauma repair and can result in liver failure which has a high mortality rate1-2. Therefore murine studies of hepatic ischemia have become an important field of research by providing the opportunity to utilize pharmacological and genetic studies3-9. Specifically, conditional mice with tissue specific deletion of a gene (cre, flox system) provide insights into the role of proteins in particular tissues10-13 . Because of the technical difficulty associated with manually clamping the portal triad in mice, we performed a systematic evaluation using a hanging-weight system for portal triad occlusion which has been previously described3. By using a hanging-weight system we place a suture around the left branch of the portal triad without causing any damage to the hepatic lobes, since also the finest clamps available can cause hepatic tissue damage because of the close location of liver tissue to the vessels. Furthermore, the right branch of the hepatic triad is still perfused thus no intestinal congestion occurs with this technique as blood flow to the right hepatic lobes is preserved. Furthermore, the portal triad is only manipulated once throughout the entire surgical procedure. As a result, procedures like pre-conditioning, with short times of ischemia and reperfusion, can be easily performed. Systematic evaluation of this model by performing different ischemia and reperfusion times revealed a close correlation of hepatic ischemia time with liver damage as measured by alanine (ALT) and aspartate (AST) aminotransferase serum levels3,9. Taken together, these studies confirm highly reproducible liver injury when using the hanging-weight system for hepatic ischemia and intermittent reperfusion. Thus, this technique might be useful for other investigators interested in liver ischemia studies in mice. Therefore the video clip provides a detailed step-by-step description of this technique.
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König K, Köhler D, Granja T, Jennewein C, Tran N, Mirakaj V, Kröhnert F, Rosenberger P. The uncoordinated-5 homolog B receptor affects hepatic ischemia reperfusion injury. PLoS One 2012; 7:e41085. [PMID: 22848430 PMCID: PMC3405071 DOI: 10.1371/journal.pone.0041085] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 06/17/2012] [Indexed: 11/18/2022] Open
Abstract
Recent evidence has demonstrated additional roles for the neuronal guidance protein receptor UNC5B outside the nervous system. Given the fact that ischemia reperfusion injury (IRI) of the liver is a common source of liver dysfunction and the role of UNC5B during an acute inflammatory response we investigated the role of UNC5B on acute hepatic IRI. We report here that UNC5B(+/-) mice display reduced hepatic IRI and neutrophil (PMN) infiltration compared to WT controls. This correlated with serum levels of lactate dehydrogenase (LDH), aspartate- (AST) and alanine- (ALT) aminotransferase, the presence of PMN within ischemic hepatic tissue, and serum levels of inflammatory cytokines. Moreover, injection of an anti-UNC5B antibody resulted in a significant reduction of hepatic IR injury. This was associated with reduced parameters of liver injury (LDH, ALT, AST) and accumulation of PMN within the injured hepatic tissue. In conclusion our studies demonstrate a significant role for UNC5B in the development of hepatic IRI and identified UNC5B as a potential drug target to prevent liver dysfunction in the future.
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Affiliation(s)
- Klemens König
- Department of Anaesthesiology and Intensive Care Medicine, Tübingen University Hospital, Eberhard-Karls University Tübingen, Tübingen, Germany
- Clinic of Anaesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt am Main, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
| | - David Köhler
- Department of Anaesthesiology and Intensive Care Medicine, Tübingen University Hospital, Eberhard-Karls University Tübingen, Tübingen, Germany
| | - Tiago Granja
- Department of Anaesthesiology and Intensive Care Medicine, Tübingen University Hospital, Eberhard-Karls University Tübingen, Tübingen, Germany
- Clinic of Anaesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt am Main, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
| | - Carla Jennewein
- Clinic of Anaesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt am Main, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
| | - Nguyen Tran
- Clinic of Anaesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt am Main, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
| | - Valbona Mirakaj
- Department of Anaesthesiology and Intensive Care Medicine, Tübingen University Hospital, Eberhard-Karls University Tübingen, Tübingen, Germany
- Department of Anaesthesiology, Perioperative, and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women's Hospital Harvard Medical School, Boston, Massachusetts, United States of America
| | - Friedemann Kröhnert
- Department of Anaesthesiology and Intensive Care Medicine, Tübingen University Hospital, Eberhard-Karls University Tübingen, Tübingen, Germany
| | - Peter Rosenberger
- Department of Anaesthesiology and Intensive Care Medicine, Tübingen University Hospital, Eberhard-Karls University Tübingen, Tübingen, Germany
- * E-mail:
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Köhler D, Birk P, König K, Straub A, Eldh T, Morote-Garcia JC, Rosenberger P. Phosphorylation of vasodilator-stimulated phosphoprotein (VASP) dampens hepatic ischemia-reperfusion injury. PLoS One 2011; 6:e29494. [PMID: 22216296 PMCID: PMC3245274 DOI: 10.1371/journal.pone.0029494] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 11/29/2011] [Indexed: 01/29/2023] Open
Abstract
Recent work has demonstrated that the formation of platelet neutrophil complexes (PNCs) affects inflammatory tissue injury. Vasodilator-stimulated phosphoprotein (VASP) is crucially involved into the control of PNC formation and myocardial reperfusion injury. Given the clinical importance of hepatic IR injury we pursued the role of VASP during hepatic ischemia followed by reperfusion. We report here that VASP−/− animals demonstrate reduced hepatic IR injury compared to wildtype (WT) controls. This correlated with serum levels of lactate dehydrogenase (LDH), aspartate (AST) and alanine (ALT) aminotransferase and the presence of PNCs within ischemic hepatic tissue and could be confirmed using repression of VASP through siRNA. In studies employing bone marrow chimeric mice we identified hematopoietic VASP to be of crucial importance for the extent of hepatic injury. Phosphorylation of VASP on Ser153 through Prostaglandin E1 or on Ser235 through atrial natriuretic peptide resulted in a significant reduction of hepatic IR injury. This was associated with a reduced presence of PNCs in ischemic hepatic tissue. Taken together, these studies identified VASP and VASP phosphorylation as crucial target for future hepatoprotective strategies.
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Affiliation(s)
- David Köhler
- Department of Anesthesiology and Intensive Care Medicine, University Hospital, Tübingen, Germany
| | - Philipp Birk
- Department of Anesthesiology and Intensive Care Medicine, University Hospital, Tübingen, Germany
| | - Klemens König
- Clinic of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt am Main, Johann Wolfgang Goethe University, Frankfurt, Germany
| | - Andreas Straub
- Department of Anesthesiology and Intensive Care Medicine, University Hospital, Tübingen, Germany
| | - Therese Eldh
- Department of Radiation Oncology, University Hospital, Tübingen, Germany
| | - Julio C. Morote-Garcia
- Department of Anesthesiology and Intensive Care Medicine, University Hospital, Tübingen, Germany
| | - Peter Rosenberger
- Department of Anesthesiology and Intensive Care Medicine, University Hospital, Tübingen, Germany
- Clinic of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt am Main, Johann Wolfgang Goethe University, Frankfurt, Germany
- * E-mail:
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16
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Colgan SP, Eltzschig HK. Adenosine and hypoxia-inducible factor signaling in intestinal injury and recovery. Annu Rev Physiol 2011; 74:153-75. [PMID: 21942704 DOI: 10.1146/annurev-physiol-020911-153230] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The gastrointestinal mucosa has proven to be an interesting tissue in which to investigate disease-related metabolism. In this review, we outline some of the evidence that implicates hypoxia-mediated adenosine signaling as an important signature within both healthy and diseased mucosa. Studies derived from cultured cell systems, animal models, and human patients have revealed that hypoxia is a significant component of the inflammatory microenvironment. These studies have revealed a prominent role for hypoxia-induced factor (HIF) and hypoxia signaling at several steps along the adenine nucleotide metabolism and adenosine receptor signaling pathways. Likewise, studies to date in animal models of intestinal inflammation have demonstrated an almost uniformly beneficial influence of HIF stabilization on disease outcomes. Ongoing studies to define potential similarities with and differences between innate and adaptive immune responses will continue to teach us important lessons about the complexity of the gastrointestinal tract. Such information has provided new insights into disease pathogenesis and, importantly, will provide insights into new therapeutic targets.
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Affiliation(s)
- Sean P Colgan
- Departments of Medicine and Anesthesiology and the Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado 80045, USA.
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Abstract
Ischemia and reperfusion-elicited tissue injury contributes to morbidity and mortality in a wide range of pathologies, including myocardial infarction, ischemic stroke, acute kidney injury, trauma, circulatory arrest, sickle cell disease and sleep apnea. Ischemia-reperfusion injury is also a major challenge during organ transplantation and cardiothoracic, vascular and general surgery. An imbalance in metabolic supply and demand within the ischemic organ results in profound tissue hypoxia and microvascular dysfunction. Subsequent reperfusion further enhances the activation of innate and adaptive immune responses and cell death programs. Recent advances in understanding the molecular and immunological consequences of ischemia and reperfusion may lead to innovative therapeutic strategies for treating patients with ischemia and reperfusion-associated tissue inflammation and organ dysfunction.
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Affiliation(s)
- Holger K Eltzschig
- Department of Anesthesiology, Mucosal Inflammation Program, University of Colorado, Aurora, Colorado, USA.
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Thorling CA, Liu X, Burczynski FJ, Fletcher LM, Gobe GC, Roberts MS. Multiphoton microscopy can visualize zonal damage and decreased cellular metabolic activity in hepatic ischemia-reperfusion injury in rats. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:116011. [PMID: 22112116 DOI: 10.1117/1.3647597] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Ischemia-reperfusion (I/R) injury is a common occurrence in liver surgery. In orthotopic transplantation, the donor liver is exposed to periods of ischemia and when oxygenated blood is reintroduced to the liver, oxidative stress may develop and lead to graft failure. The aim of this project was to investigate whether noninvasive multiphoton and fluorescence lifetime imaging microscopy, without external markers, were useful in detecting early liver damage caused by I/R injury. Localized hepatic ischemia was induced in rats for 1 h followed by 4 h reperfusion. Multiphoton and fluorescence lifetime imaging microscopy was conducted prior to ischemia and up to 4 h of reperfusion and compared to morphological and biochemical assessment of liver damage. Liver function was significantly impaired at 2 and 4 h of reperfusion. Multiphoton microscopy detected liver damage at 1 h of reperfusion, manifested by vacuolated cells and heterogeneous spread of damage over the liver. The damage was mainly localized in the midzonal region of the liver acinus. In addition, fluorescence lifetime imaging showed a decrease in cellular metabolic activity. Multiphoton and fluorescence lifetime imaging microscopy detected evidence of early I/R injury both structurally and functionally. This provides a simple noninvasive technique useful for following progressive liver injury without external markers.
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Affiliation(s)
- Camilla A Thorling
- The University of Queensland, School of Medicine, Woolloongabba, Queensland, 4102, Australia
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Preconditioning with physiological levels of ethanol protect kidney against ischemia/reperfusion injury by modulating oxidative stress. PLoS One 2011; 6:e25811. [PMID: 22022451 PMCID: PMC3192120 DOI: 10.1371/journal.pone.0025811] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Accepted: 09/11/2011] [Indexed: 01/01/2023] Open
Abstract
Background Oxidative stress due to excessive production of reactive oxygen species (ROS) and subsequent lipid peroxidation plays a critical role in renal ischemia/reperfusion (IR) injury. The purpose of current study is to demonstrate the effect of antecedent ethanol exposure on IR-induced renal injury by modulation of oxidative stress. Materials and Methods Bilateral renal warm IR was induced in male C57BL/6 mice after ethanol or saline administration. Blood ethanol concentration, kidney function, histological damage, inflammatory infiltration, cytokine production, oxidative stress, antioxidant capacity and Aldehyde dehydrogenase (ALDH) enzymatic activity were assessed to evaluate the impact of antecedent ethanol exposure on IR-induced renal injury. Results After bilateral kidney ischemia, mice preconditioned with physiological levels of ethanol displayed significantly preserved renal function along with less histological tubular damage as manifested by the reduced inflammatory infiltration and cytokine production. Mechanistic studies revealed that precondition of mice with physiological levels of ethanol 3 h before IR induction enhanced antioxidant capacity characterized by significantly higher superoxidase dismutase (SOD) activities. Our studies further demonstrated that ethanol pretreatment specifically increased ALDH2 activity, which then suppressed lipid peroxidation by promoting the detoxification of Malondialdehyde (MDA) and 4-hydroxynonenal (HNE). Conclusions Our results provide first line of evidence indicating that antecedent ethanol exposure can provide protection for kidneys against IR-induced injury by enhancing antioxidant capacity and preventing lipid peroxidation. Therefore, ethanol precondition and ectopic ALDH2 activation could be potential therapeutic approaches to prevent renal IR injury relevant to various clinical conditions.
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20
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Koeppen M, Eckle T, Eltzschig HK. Pressure controlled ventilation to induce acute lung injury in mice. J Vis Exp 2011:2525. [PMID: 21587159 PMCID: PMC3197099 DOI: 10.3791/2525] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Murine models are extensively used to investigate acute injuries of different organs systems (1-34). Acute lung injury (ALI), which occurs with prolonged mechanical ventilation, contributes to morbidity and mortality of critical illness, and studies on novel genetic or pharmacological targets are areas of intense investigation (1-3, 5, 8, 26, 30, 33-36). ALI is defined by the acute onset of the disease, which leads to non-cardiac pulmonary edema and subsequent impairment of pulmonary gas exchange (36). We have developed a murine model of ALI by using a pressure-controlled ventilation to induce ventilator-induced lung injury (2). For this purpose, C57BL/6 mice are anesthetized and a tracheotomy is performed followed by induction of ALI via mechanical ventilation. Mice are ventilated in a pressure-controlled setting with an inspiratory peak pressure of 45 mbar over 1 - 3 hours. As outcome parameters, pulmonary edema (wet-to-dry ratio), bronchoalveolar fluid albumin content, bronchoalveolar fluid and pulmonary tissue myeloperoxidase content and pulmonary gas exchange are assessed (2). Using this technique we could show that it sufficiently induces acute lung inflammation and can distinguish between different treatment groups or genotypes (1-3, 5). Therefore this technique may be helpful for researchers who pursue molecular mechanisms involved in ALI using a genetic approach in mice with gene-targeted deletion.
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Hart ML, Gorzolla IC, Schittenhelm J, Robson SC, Eltzschig HK. SP1-dependent induction of CD39 facilitates hepatic ischemic preconditioning. THE JOURNAL OF IMMUNOLOGY 2010; 184:4017-24. [PMID: 20207994 DOI: 10.4049/jimmunol.0901851] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Ischemia/reperfusion injury (IRI) of the liver is an important cause of hepatic dysfunction. Ischemic preconditioning (IP) is associated with adenosine-mediated tissue protection from subsequent IRI. Extracellular nucleotides (e.g., ATP) represent the main source for extracellular adenosine. Therefore, we hypothesized that phosphohydrolysis of ATP/ADP via the ectonucleoside triphosphate diphosphohydrolase-1 (CD39), conversion of ATP/ADP to AMP, mediates IP-dependent liver protection. We found that hepatic IP was associated with significant induction of CD39 transcript, heightened protein expression, and improved outcomes after IRI. Targeted gene deletion or pharmacological inhibition of CD39 abolished hepatoprotection by IP as measured by serum markers of liver injury or histology. Therapeutic studies to mimic IP with i.p. apyrase (a soluble ectonucleoside triphosphate diphosphohydrolase, NTPDase) in the absence of IP attenuated hepatic injury after IRI. In additional in vivo studies, small interfering RNA treatment was used to achieve repression of the transcription factor Sp1, known to be implicated in CD39 transcriptional regulation. In fact, Sp1 small interfering RNA treatment was associated with attenuated CD39 induction and increased hepatic injury in vivo. Our data suggest a Sp1-dependent regulatory pathway for CD39 during hepatic IP. These studies reveal a novel role of CD39 in hepatic protection and suggest soluble apyrase for the treatment of liver ischemia.
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Affiliation(s)
- Melanie L Hart
- Department of Anesthesiology and Intensive Care Medicine, University of Tübingen, Tübingen, Germany.
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Hart ML, Much C, Gorzolla IC, Schittenhelm J, Kloor D, Stahl GL, Eltzschig HK. Extracellular adenosine production by ecto-5'-nucleotidase protects during murine hepatic ischemic preconditioning. Gastroenterology 2008; 135:1739-1750.e3. [PMID: 18804111 DOI: 10.1053/j.gastro.2008.07.064] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 06/26/2008] [Accepted: 07/24/2008] [Indexed: 02/02/2023]
Abstract
BACKGROUND & AIMS The liver tolerates ischemia/reperfusion (IR) poorly. The discovery of ischemic preconditioning (IP) has raised hopes that natural pathways could be activated to increase hepatic resistance to ischemia. However, mechanisms of hepatic IP remain largely unknown. Extracellular adenosine has been implicated as an innate anti-inflammatory metabolite, particularly during ischemia. We investigated whether ecto-5'-nucleotidase (CD73), the "pacemaker" enzyme of extracellular adenosine production, is critical for hepatic protection by IP. METHODS Mice were subjected to 4 cycles of portal triad occlusion and reperfusion (3 minutes of ischemia/3 minutes of reperfusion) prior to IR or IR alone. RESULTS Hepatic IP was associated with a significant induction of CD73 transcript and protein. Targeted gene deletion or pharmacologic inhibition of CD73 abolished hepatic protection by IP as measured by lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase serum levels or histologic injury. Increases in extracellular adenosine with IP were significantly attenuated in cd73-deficient (cd73(-/-)) mice. Reconstitution of cd73(-/-) mice with soluble 5'-nucleotidase resulted in complete restoration of hepatoprotection by IP, and hepatic injury following ischemia was attenuated by treatment of WT mice with soluble 5'-nucleotidase. Mice deficient in CD73 did not demonstrate the same degree of IP-dependent inhibition of acute phase complement gene expression/activation as did wild-type mice suggesting that extracellular adenosine attenuates hepatic IR via complement regulation. CONCLUSIONS Extracellular adenosine production by CD73 mediates protection during murine hepatic IP. Use of soluble 5'-nucleotidase may be a potential therapeutic for hepatic ischemia.
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Affiliation(s)
- Melanie L Hart
- Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative, and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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23
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Eckle T, Füllbier L, Grenz A, Eltzschig HK. Usefulness of pressure-controlled ventilation at high inspiratory pressures to induce acute lung injury in mice. Am J Physiol Lung Cell Mol Physiol 2008; 295:L718-24. [PMID: 18708630 DOI: 10.1152/ajplung.90298.2008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute lung injury (ALI), as occurs with prolonged mechanical ventilation, contributes to morbidity and mortality of critical illness, and studies on novel genetic or pharmacological targets are areas of intense investigation. Here, we systematically tested a murine model of ALI by using pressure-controlled ventilation to induce ventilator-induced lung injury. For this purpose, C57BL/6 or Sv129 mice were anesthetized and underwent tracheotomy followed by induction of ALI via mechanical ventilation. Mice were ventilated in a pressure-controlled setting at different inspiratory pressure levels (15-45 mbar) and over different times (0-90 min, 100% oxygen). As outcome parameters, we assessed pulmonary edema (wet-to-dry ratios), bronchoalveolar fluid albumin content, pulmonary myeloperoxidase activity, macrophage inflammatory protein-2, and pulmonary gas exchange. These studies revealed maximal differences in severity of lung injury between different mouse strains after 90 min of ventilation time at 45 mbar. Use of lower concentrations of inspired oxygen did not alter disease severity. Increases of CD73 transcript (5'-ectonucleotidase, pacemaker of extracellular adenosine production) or total pulmonary adenosine levels with mechanical ventilation were less pronounced in C57BL/6 mice, suggesting attenuated adenosine protection in C57BL/6 mice. Together, these studies demonstrate feasibility of this model to induce murine ALI.
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Affiliation(s)
- Tobias Eckle
- University of Colorado Denver Dept. of Anesthesiology and Perioperative Medicine, Aurora, CO 80045, USA
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ATP release from vascular endothelia occurs across Cx43 hemichannels and is attenuated during hypoxia. PLoS One 2008; 3:e2801. [PMID: 18665255 PMCID: PMC2474679 DOI: 10.1371/journal.pone.0002801] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2008] [Accepted: 07/05/2008] [Indexed: 01/22/2023] Open
Abstract
Background Extracellular ATP is an important signaling molecule for vascular adaptation to limited oxygen availability (hypoxia). Here, we pursued the contribution of vascular endothelia to extracellular ATP release under hypoxic conditions. Methodology, Principal Findings We gained first insight from studying ATP release from endothelia (HMEC-1) pre-exposed to hypoxia. Surprisingly, we found that ATP release was significantly attenuated following hypoxia exposure (2% oxygen, 22±3% after 48 h). In contrast, intracellular ATP was unchanged. Similarly, lactate-dehydrogenase release into the supernatants was similar between normoxic or hypoxic endothelia, suggesting that differences in lytic ATP release between normoxia or hypoxia are minimal. Next, we used pharmacological strategies to study potential mechanisms for endothelial-dependent ATP release (eg, verapamil, dipyridamole, 18-alpha-glycyrrhetinic acid, anandamide, connexin-mimetic peptides). These studies revealed that endothelial ATP release occurs – at least in part - through connexin 43 (Cx43) hemichannels. A real-time RT-PCR screen of endothelial connexin expression showed selective repression of Cx43 transcript and additional studies confirmed time-dependent Cx43 mRNA, total and surface protein repression during hypoxia. In addition, hypoxia resulted in Cx43-serine368 phosphorylation, which is known to switch Cx43 hemi-channels from an open to a closed state. Conclusions/Significance Taken together, these studies implicate endothelial Cx43 in hypoxia-associated repression of endothelial ATP release.
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