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Balter LJ, Li X, Schwieler L, Erhardt S, Axelsson J, Olsson MJ, Lasselin J, Lekander M. Lipopolysaccharide-induced changes in the kynurenine pathway and symptoms of sickness behavior in humans. Psychoneuroendocrinology 2023; 153:106110. [PMID: 37075653 DOI: 10.1016/j.psyneuen.2023.106110] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 03/07/2023] [Accepted: 04/06/2023] [Indexed: 04/21/2023]
Abstract
Metabolites of the kynurenine pathway are hypothesized to be implicated in inflammation-associated depression, but there is a lack of experimental studies in humans assessing the kinetics of kynurenine metabolites in relation to experimentally-induced sickness. The aim of the present study was to assess changes in the kynurenine pathway and to explore its relation to symptoms of sickness behavior during an acute experimental immune challenge. This double-blind placebo-controlled randomized cross-over study included 22 healthy human participants (n = 21 both sessions, Mage = 23.4, SD = 3.6, nine women) who received an intravenous injection of 2.0 ng/kg lipopolysaccharide (LPS) and saline (placebo) on two different occasions in a randomized order. Blood samples (0 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 5 h, 7 h post-injection) were analyzed for kynurenine metabolites and inflammatory cytokines. The intensity of symptoms of sickness behavior was assessed using the 10-item Sickness Questionnaire at 0 h, 1.5 h, 3 h, 5 h, and 7 h post-injection. LPS induced significantly lower concentrations of plasma tryptophan (at 2 h, 4 h, 5 h, and 7 h post-injection), kynurenine (at 2 h, 3 h, 4 h, and 5 h post-injection), nicotinamide (at 4 h, 5 h, and 7 h post-injection), and higher levels for quinolinic acid at 5 h post-injection as compared to placebo. LPS did not affect kynurenic acid, 3-hydroxykynurenine, and picolinic acid. The development of the sickness symptoms was largely similar across items, with the highest levels around 1.5-3 h post-injection. Changes in plasma levels of kynurenine metabolites seem to coincide rather than precede or follow changes in subjective sickness. Exploratory analyses indicate that higher Sickness Questionnaire total scores at 1.5-5 h post-injection were correlated with lower kynurenic acid and nicotinamide levels. These results lend further support for LPS-induced changes in the kynurenine pathway, but may not, as interpreted from blood levels, causally link to LPS-induced acute symptoms of sickness behavior. Future research may consider a larger sample to further scrutinize the role of the kynurenine pathway in the sickness response.
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Affiliation(s)
- Leonie Jt Balter
- Department of Clinical Neuroscience, Division of Psychology, Karolinska Institutet, Stockholm, Sweden; Stress Research Institute, Department of Psychology, Stockholm University, Stockholm, Sweden.
| | - Xueqi Li
- Department of Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Lilly Schwieler
- Department of Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Sophie Erhardt
- Department of Physiology, Karolinska Institutet, Stockholm, Sweden
| | - John Axelsson
- Department of Clinical Neuroscience, Division of Psychology, Karolinska Institutet, Stockholm, Sweden; Stress Research Institute, Department of Psychology, Stockholm University, Stockholm, Sweden
| | - Mats J Olsson
- Department of Clinical Neuroscience, Division of Psychology, Karolinska Institutet, Stockholm, Sweden
| | - Julie Lasselin
- Department of Clinical Neuroscience, Division of Psychology, Karolinska Institutet, Stockholm, Sweden; Stress Research Institute, Department of Psychology, Stockholm University, Stockholm, Sweden; Osher Center for Integrative Health, Department of Clinical Neuroscience, Karolinska Institutet, Sweden
| | - Mats Lekander
- Department of Clinical Neuroscience, Division of Psychology, Karolinska Institutet, Stockholm, Sweden; Stress Research Institute, Department of Psychology, Stockholm University, Stockholm, Sweden; Osher Center for Integrative Health, Department of Clinical Neuroscience, Karolinska Institutet, Sweden
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Unbalanced IDO1/IDO2 Endothelial Expression and Skewed Keynurenine Pathway in the Pathogenesis of COVID-19 and Post-COVID-19 Pneumonia. Biomedicines 2022; 10:biomedicines10061332. [PMID: 35740354 PMCID: PMC9220124 DOI: 10.3390/biomedicines10061332] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 05/29/2022] [Accepted: 06/02/2022] [Indexed: 11/17/2022] Open
Abstract
Despite intense investigation, the pathogenesis of COVID-19 and the newly defined long COVID-19 syndrome are not fully understood. Increasing evidence has been provided of metabolic alterations characterizing this group of disorders, with particular relevance of an activated tryptophan/kynurenine pathway as described in this review. Recent histological studies have documented that, in COVID-19 patients, indoleamine 2,3-dioxygenase (IDO) enzymes are differentially expressed in the pulmonary blood vessels, i.e., IDO1 prevails in early/mild pneumonia and in lung tissues from patients suffering from long COVID-19, whereas IDO2 is predominant in severe/fatal cases. We hypothesize that IDO1 is necessary for a correct control of the vascular tone of pulmonary vessels, and its deficiency in COVID-19 might be related to the syndrome’s evolution toward vascular dysfunction. The complexity of this scenario is discussed in light of possible therapeutic manipulations of the tryptophan/kynurenine pathway in COVID-19 and post-acute COVID-19 syndromes.
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Millischer V, Heinzl M, Faka A, Resl M, Trepci A, Klammer C, Egger M, Dieplinger B, Clodi M, Schwieler L. Intravenous administration of LPS activates the kynurenine pathway in healthy male human subjects: a prospective placebo-controlled cross-over trial. J Neuroinflammation 2021; 18:158. [PMID: 34273987 PMCID: PMC8286561 DOI: 10.1186/s12974-021-02196-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 06/16/2021] [Indexed: 12/12/2022] Open
Abstract
Background Administration of lipopolysaccharide (LPS) from Gram-negative bacteria, also known as the human endotoxemia model, is a standardized and safe model of human inflammation. Experimental studies have revealed that peripheral administration of LPS leads to induction of the kynurenine pathway followed by depressive-like behavior and cognitive dysfunction in animals. The aim of the present study is to investigate how acute intravenous LPS administration affects the kynurenine pathway in healthy male human subjects. Methods The present study is a prospective, single-blinded, randomized, placebo-controlled cross-over study to investigate the effects of intravenously administered LPS (Escherichia coli O113, 2 ng/kg) on tryptophan and kynurenine metabolites over 48 h and their association with interleukin-6 (IL-6) and C-reactive protein (CRP). The study included 10 healthy, non-smoking men (18–40 years) free from medication. Statistical differences in tryptophan and kynurenine metabolites as well as associations with IL-6 and CRP in LPS and placebo treated subjects were assessed with linear mixed-effects models. Results Systemic injection of LPS was associated with significantly lower concentrations of plasma tryptophan and kynurenine after 4 h, as well as higher concentrations of quinolinic acid (QUIN) after 48 h compared to the placebo injection. No differences were found in kynurenic acid (KYNA) or picolinic acid plasma concentrations between LPS or placebo treatment. The KYNA/kynurenine ratio peaked at 6 h post LPS injection while QUIN/kynurenine maintained significantly higher from 3 h post LPS injection until 24 h. The kynurenine/tryptophan ratio was higher at 24 h and 48 h post LPS treatment. Finally, we report an association between the kynurenine/tryptophan ratio and CRP. Conclusions Our findings strongly support the concept that an inflammatory challenge with LPS induces the kynurenine pathway in humans, activating both the neurotoxic (QUIN) and neuroprotective (KYNA) branch of the kynurenine pathway. Trial registration This study is based on a study registered at ClinicalTrials.gov, NCT03392701. Registered 21 December 2017. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02196-x.
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Affiliation(s)
- Vincent Millischer
- Department of Molecular Medicine and Surgery (MMK), Karolinska Institutet, Stockholm, Sweden.,Translational Psychiatry, Center for Molecular Medicine, Karolinska University Hospital, Stockholm, Sweden.,Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Matthias Heinzl
- Department of Internal Medicine, Konventhospital Barmherzige Brueder (St. John of God Hospital), Seilerstaette 2, 4021, Linz, Austria.,ICMR-Institute for Cardiovascular and Metabolic Research, JKU Linz, Linz, Austria
| | - Anthi Faka
- Department of Physiology & Pharmacology, Sec. Neuropsychoimmunology, Karolinska Institutet, Stockholm, Sweden
| | - Michael Resl
- Department of Internal Medicine, Konventhospital Barmherzige Brueder (St. John of God Hospital), Seilerstaette 2, 4021, Linz, Austria.,ICMR-Institute for Cardiovascular and Metabolic Research, JKU Linz, Linz, Austria
| | - Ada Trepci
- Department of Physiology & Pharmacology, Sec. Neuropsychoimmunology, Karolinska Institutet, Stockholm, Sweden
| | - Carmen Klammer
- Department of Internal Medicine, Konventhospital Barmherzige Brueder (St. John of God Hospital), Seilerstaette 2, 4021, Linz, Austria.,ICMR-Institute for Cardiovascular and Metabolic Research, JKU Linz, Linz, Austria
| | - Margot Egger
- Department of Laboratory Medicine, Konventhospital Barmherzige Brueder (St. John of God Hospital), Linz, Austria
| | - Benjamin Dieplinger
- Department of Laboratory Medicine, Konventhospital Barmherzige Brueder (St. John of God Hospital), Linz, Austria
| | - Martin Clodi
- Department of Internal Medicine, Konventhospital Barmherzige Brueder (St. John of God Hospital), Seilerstaette 2, 4021, Linz, Austria. .,ICMR-Institute for Cardiovascular and Metabolic Research, JKU Linz, Linz, Austria.
| | - Lilly Schwieler
- Department of Physiology & Pharmacology, Sec. Neuropsychoimmunology, Karolinska Institutet, Stockholm, Sweden
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Meireson A, Devos M, Brochez L. IDO Expression in Cancer: Different Compartment, Different Functionality? Front Immunol 2020; 11:531491. [PMID: 33072086 PMCID: PMC7541907 DOI: 10.3389/fimmu.2020.531491] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 08/25/2020] [Indexed: 12/11/2022] Open
Abstract
Indoleamine 2,3-dioxygenase 1 (IDO1) is a cytosolic haem-containing enzyme involved in the degradation of tryptophan to kynurenine. Although initially thought to be solely implicated in the modulation of innate immune responses during infection, subsequent discoveries demonstrated IDO1 as a mechanism of acquired immune tolerance. In cancer, IDO1 expression/activity has been observed in tumor cells as well as in the tumor-surrounding stroma, which is composed of endothelial cells, immune cells, fibroblasts, and mesenchymal cells. IDO1 expression/activity has also been reported in the peripheral blood. This manuscript reviews available data on IDO1 expression, mechanisms of its induction, and its function in cancer for each of these compartments. In-depth study of the biological function of IDO1 according to the expressing (tumor) cell can help to understand if and when IDO1 inhibition can play a role in cancer therapy.
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Affiliation(s)
- Annabel Meireson
- Department of Dermatology, Ghent University Hospital, Ghent, Belgium.,Cancer Research Institute Ghent, Ghent, Belgium
| | - Michael Devos
- Department of Dermatology, Ghent University Hospital, Ghent, Belgium
| | - Lieve Brochez
- Department of Dermatology, Ghent University Hospital, Ghent, Belgium.,Cancer Research Institute Ghent, Ghent, Belgium
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Hunt C, Macedo E Cordeiro T, Suchting R, de Dios C, Cuellar Leal VA, Soares JC, Dantzer R, Teixeira AL, Selvaraj S. Effect of immune activation on the kynurenine pathway and depression symptoms - A systematic review and meta-analysis. Neurosci Biobehav Rev 2020; 118:514-523. [PMID: 32853625 DOI: 10.1016/j.neubiorev.2020.08.010] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 07/30/2020] [Accepted: 08/14/2020] [Indexed: 12/28/2022]
Abstract
Dysregulated kynurenine (KYN) pathway has been implicated in the pathophysiology of depression. In this systematic review, we examined the relationship between kynurenine pathway metabolites (KYN, kynurenic acid KYNA, tryptophan TRP, quinolinic acid QUIN, KYN/TRP ratio) and depression symptoms in the context of pro-inflammatory activation and immune response. Out of 5,082 articles, fifteen studies were suitable; ten studies (N = 315 medically ill patients treated with interferon-alpha IFN-α) reported baseline and post-intervention plasma KYN, TRP and KYN/TRP ratios which were included in quantitative meta-analysis. Data from five studies were summarized (IFN-α, interferon-beta IFN-β, and lipopolysaccharide LPS). We found that IFN-α treatment in patients with chronic illnesses was associated with decreased TRP, increased levels of KYN and KYN/TRP ratio and depression scores from baseline to follow-up at both 4 and 24 weeks. Our findings suggest that increased risk of depression observed after immune-activating agents in patients with chronic medical illnesses is likely mediated by the kynurenine pathway. Further prospective studies are required to investigate the exact pathophysiology of the KYN pathway in depression.
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Affiliation(s)
- Charlotte Hunt
- The University of Texas Health Science Center at Houston, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA
| | - Thiago Macedo E Cordeiro
- Louis A. Faillace, MD, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), 1941 East Rd, Houston, TX, 77054, USA
| | - Robert Suchting
- Louis A. Faillace, MD, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), 1941 East Rd, Houston, TX, 77054, USA
| | - Constanza de Dios
- Louis A. Faillace, MD, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), 1941 East Rd, Houston, TX, 77054, USA
| | - Valeria A Cuellar Leal
- Louis A. Faillace, MD, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), 1941 East Rd, Houston, TX, 77054, USA
| | - Jair C Soares
- Louis A. Faillace, MD, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), 1941 East Rd, Houston, TX, 77054, USA
| | - Robert Dantzer
- Department of Symptom Research, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX, 77030, USA
| | - Antonio L Teixeira
- Louis A. Faillace, MD, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), 1941 East Rd, Houston, TX, 77054, USA
| | - Sudhakar Selvaraj
- Louis A. Faillace, MD, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), 1941 East Rd, Houston, TX, 77054, USA; Houston Methodist Research Institute, Institute for Academic Medicine, 6670 Bertner St., Houston, TX, 77030, USA.
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Early Immune Regulatory Changes in a Primary Controlled Human Plasmodium vivax Infection: CD1c + Myeloid Dendritic Cell Maturation Arrest, Induction of the Kynurenine Pathway, and Regulatory T Cell Activation. Infect Immun 2017; 85:IAI.00986-16. [PMID: 28320838 DOI: 10.1128/iai.00986-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/15/2017] [Indexed: 01/03/2023] Open
Abstract
Plasmodium vivax malaria remains a major public health problem. The requirements for acquisition of protective immunity to the species are not clear. Dendritic cells (DC) are essential for immune cell priming but also perform immune regulatory functions, along with regulatory T cells (Treg). An important function of DC involves activation of the kynurenine pathway via indoleamine 2,3-dioxygenase (IDO). Using a controlled human experimental infection study with blood-stage P. vivax, we characterized plasmacytoid DC (pDC) and myeloid DC (mDC) subset maturation, CD4+ CD25+ CD127lo Treg activation, and IDO activity. Blood samples were collected from six healthy adults preinoculation, at peak parasitemia (day 14; ∼31,400 parasites/ml), and 24 and 48 h after antimalarial treatment. CD1c+ and CD141+ mDC and pDC numbers markedly declined at peak parasitemia, while CD16+ mDC numbers appeared less affected. HLA-DR expression was selectively reduced on CD1c+ mDC, increased on CD16+ mDC, and was unaltered on pDC. Plasma IFN-γ increased significantly and was correlated with an increased kynurenine/tryptophan (KT) ratio, a measure of IDO activity. At peak parasitemia, Treg presented an activated CD4+ CD25+ CD127lo CD45RA- phenotype and upregulated TNFR2 expression. In a mixed-effects model, the KT ratio was positively associated with an increase in activated Treg. Our data demonstrate that a primary P. vivax infection exerts immune modulatory effects by impairing HLA-DR expression on CD1c+ mDC while activating CD16+ mDC. Induction of the kynurenine pathway and increased Treg activation, together with skewed mDC maturation, suggest P. vivax promotes an immunosuppressive environment, likely impairing the development of a protective host immune response.
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Ochoa Gautier JB, Martindale RG, Rugeles SJ, Hurt RT, Taylor B, Heyland DK, McClave SA. How Much and What Type of Protein Should a Critically Ill Patient Receive? Nutr Clin Pract 2017; 32:6S-14S. [PMID: 28388376 DOI: 10.1177/0884533617693609] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Protein loss, manifested as loss of muscle mass, is observed universally in all critically ill patients. Depletion of muscle mass is associated with impaired function and poor outcomes. In extreme cases, protein malnutrition is manifested by respiratory failure, lack of wound healing, and immune dysfunction. Protecting muscle loss focused initially on meeting energy requirements. The assumption was that protein was being used (through oxidation) as an energy source. In healthy individuals, small amounts of glucose (approximately 400 calories) protect muscle loss and decrease amino acid oxidation (protein-sparing effect of glucose). Despite expectations of the benefits, the high provision of energy (above basal energy requirements) through the delivery of nonprotein calories has failed to demonstrate a clear benefit at curtailing protein loss. The protein-sparing effect of glucose is not clearly observed during illness. Increasing protein delivery beyond the normal nutrition requirements (0.8 g/k/d) has been investigated as an alternative solution. Over a dozen observational studies in critically ill patients suggest that higher protein delivery is beneficial at protecting muscle mass and associated with improved outcomes (decrease in mortality). Not surprisingly, new Society of Critical Care Medicine/American Society for Parenteral and Enteral Nutrition guidelines and expert recommendations suggest higher protein delivery (>1.2 g/kg/d) for critically ill patients. This article provides an introduction to the concepts that delineate the basic principles of modern medical nutrition therapy as it relates to the goal of achieving an optimal management of protein metabolism during critical care illness, highlighting successes achieved so far but also placing significant challenges limiting our success in perspective.
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Affiliation(s)
| | - Robert G Martindale
- 2 Department of Surgery, Oregon Health and Science University, Portland, Oregon, USA
| | - Saúl J Rugeles
- 3 Department of Surgery, Pontificia Universidad Javeriana, Bogota, DC, Colombia
| | - Ryan T Hurt
- 4 Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Beth Taylor
- 5 Department of Food and Nutrition, Barnes-Jewish Hospital, St Louis, Missouri, USA
| | - Daren K Heyland
- 6 Department of Medicine, Queens University, Kingston, Ontario, Canada
| | - Stephen A McClave
- 7 Department of Medicine, University of Louisville, Louisville, Kentucky, USA
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The kynurenine pathway and parasitic infections that affect CNS function. Neuropharmacology 2017; 112:389-398. [DOI: 10.1016/j.neuropharm.2016.02.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 02/19/2016] [Accepted: 02/23/2016] [Indexed: 12/14/2022]
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Schefold JC, Fritschi N, Fusch G, Bahonjic A, Doehner W, von Haehling S, Pschowski R, Storm C, Schroeder T. Influence of core body temperature on Tryptophan metabolism, kynurenines, and estimated IDO activity in critically ill patients receiving target temperature management following cardiac arrest. Resuscitation 2016; 107:107-14. [PMID: 27565863 DOI: 10.1016/j.resuscitation.2016.07.239] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 07/22/2016] [Accepted: 07/26/2016] [Indexed: 12/21/2022]
Abstract
BACKGROUND/AIMS Temperature control improves neurological prognosis in comatose cardiac arrest (CA) survivors. Previous reports demonstrate that most affected patients show signs of significant systemic inflammation. In an effort to better characterize potential temperature-related effects on key inflammatory pathways, we investigate the course of Tryptophan (Trp) levels, Tryptophan catabolites (including kynurenines) and indoleamine-2,3-dioxygenase (IDO)-activity in post CA patients. MATERIAL/METHODS In an observational blinded endpoint analysis, a total of n=270 serial samples from 20 post CA patients (63.1±16.6 yrs., 45% shockable rhythm, mean time to return of spontaneous circulation (ROSC) 26.6±16.0min) treated with target temperature management (TTM) were analyzed. Core body temperatures, course of Trp, Trp catabolites (incl. kynurenines), and estimated IDO-activity were followed up for a maximum of 7 days after ROSC. Patients were followed up until hospital discharge or death and functional outcome was recorded. RESULTS Over the 7-day observational interval, marked changes in Trp serum levels and IDO-activity were noted. In general, Trp serum levels but not IDO-activity seemed to parallel with the course of core body temperature. In explorative analyses, a correlation of Trp (rho=0.271 (95%-CI: 0.16-0.38, p<0.0001) and IDO-activity (rho=-0.155, 95%-CI: -0.27 to -0.037, p=0.01) with core body temperature was observed. Linear mixed effect models revealed a positive significant association of core body temperature with Trp serum levels (Likelihood ratio test χ(2)=6.35, p=0.012). In patients with good (vs. unfavorable) outcome, a tendency toward higher Trp serum levels, lower IDO-activity, and lower Kynurenic acid levels was noted. CONCLUSIONS We observed significant changes in Trp catabolism and IDO-activity that appeared temperature associated in post CA patients. Under hypothermia, decreased serum levels of Trp and increased IDO-activity were noted. We speculate from our data that IDO-induction during hypothermia contributes to the previously described increased susceptibility to infection or sepsis under reduced temperatures.
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Affiliation(s)
- Joerg C Schefold
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, Bern, Switzerland; Department of Nephrology and Intensive Care Medicine, Charite University Medicine, Berlin, Germany
| | - Nora Fritschi
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Gerhard Fusch
- Department of Pediatrics, McMaster University, Hamilton, Canada
| | - Aldin Bahonjic
- Department of Pediatrics, McMaster University, Hamilton, Canada
| | - Wolfram Doehner
- Centre for Stroke Research Berlin, Charité Medical School, Berlin, Germany
| | - Stephan von Haehling
- University of Göttingen Medical School, Department of Cardiology and Pneumology, Göttingen, Germany
| | - Rene Pschowski
- Department of Nephrology and Intensive Care Medicine, Charite University Medicine, Berlin, Germany; Department of Gastroenterology, Charite University Medicine, Berlin, Germany
| | - Christian Storm
- Department of Nephrology and Intensive Care Medicine, Charite University Medicine, Berlin, Germany
| | - Tim Schroeder
- Department of Nephrology and Intensive Care Medicine, Charite University Medicine, Berlin, Germany
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Wirthgen E, Hoeflich A. Endotoxin-Induced Tryptophan Degradation along the Kynurenine Pathway: The Role of Indolamine 2,3-Dioxygenase and Aryl Hydrocarbon Receptor-Mediated Immunosuppressive Effects in Endotoxin Tolerance and Cancer and Its Implications for Immunoparalysis. JOURNAL OF AMINO ACIDS 2015; 2015:973548. [PMID: 26881062 PMCID: PMC4736209 DOI: 10.1155/2015/973548] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/28/2015] [Accepted: 12/06/2015] [Indexed: 12/16/2022]
Abstract
The degradation of tryptophan (TRP) along the kynurenine pathway plays a crucial role as a neuro- and immunomodulatory mechanism in response to inflammatory stimuli, such as lipopolysaccharides (LPS). In endotoxemia or sepsis, an enhanced activation of the rate-limiting enzyme indoleamine 2,3-dioxygenase (IDO) is associated with a higher mortality risk. It is assumed that IDO induced immunosuppressive effects provoke the development of a protracted compensatory hypoinflammatory phase up to a complete paralysis of the immune system, which is characterized by an endotoxin tolerance. However, the role of IDO activation in the development of life-threatening immunoparalysis is still poorly understood. Recent reports described the impact of inflammatory IDO activation and aryl hydrocarbon receptor- (AhR-) mediated pathways on the development of LPS tolerance and immune escape of cancer cells. These immunosuppressive mechanisms offer new insights for a better understanding of the development of cellular dysfunctions in immunoparalysis. This review provides a comprehensive update of significant biological functions of TRP metabolites along the kynurenine pathway and the complex regulation of LPS-induced IDO activation. In addition, the review focuses on the role of IDO-AhR-mediated immunosuppressive pathways in endotoxin tolerance and carcinogenesis revealing the significance of enhanced IDO activity for the establishment of life-threatening immunoparalysis in sepsis.
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Affiliation(s)
- Elisa Wirthgen
- Institute of Genome Biology, Leibniz Institute for Farm Animal Biology, Germany
| | - Andreas Hoeflich
- Institute of Genome Biology, Leibniz Institute for Farm Animal Biology, Germany
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Blockade of indoleamine 2,3-dioxygenase reduces mortality from peritonitis and sepsis in mice by regulating functions of CD11b+ peritoneal cells. Infect Immun 2014; 82:4487-95. [PMID: 25114116 DOI: 10.1128/iai.02113-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Indoleamine 2,3-dioxygenase-1 (Ido), which catalyzes the first and limiting step of tryptophan catabolism, has been implicated in immune tolerance. However, the roles of Ido in systemic bacterial infection are complicated and remain controversial. To explore this issue, we examined the roles of Ido in bacterial peritonitis and sepsis after cecal ligation and puncture (CLP) in mice by using the Ido inhibitor 1-methyl-d,l-tryptophan (1-MT), by comparing Ido(+/+) and Ido(-/-) mice, or by using chimeric mice in which Ido in the bone marrow-derived cells was deficient. Ido expression in the peritoneal CD11b(+) cells and its metabolite l-kynurenine in the serum were increased after CLP. 1-MT treatment or Ido deficiency, especially in bone marrow-derived cells, reduced mortality after CLP. Compared to Ido(+/+) mice, Ido(-/-) mice showed increased recruitment of neutrophils and mononuclear cells into the peritoneal cavity and a decreased bacterial count in the blood accompanied by increased CXCL-2 and CXCL-1 mRNA in the peritoneal cells. Ido has an inhibitory effect on LPS-induced CXCL-2 and CXCL-1 production in cultured peritoneal cells. These findings indicate that inhibition of Ido reduces mortality from peritonitis and sepsis after CLP via recruitment of neutrophils and mononuclear cells by chemokine production in peritoneal CD11b(+) cells. Thus, blockade of Ido plays a beneficial role in host protection during bacterial peritonitis and sepsis.
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