Intravenous administration of LPS activates the kynurenine pathway in healthy male human subjects: a prospective placebo-controlled cross-over trial

Vincent Millischer, Matthias Heinzl, Anthi Faka, Michael Resl, Ada Trepci, Carmen Klammer, Margot Egger, Benjamin Dieplinger, Martin Clodi, Lilly Schwieler, Vincent Millischer, Matthias Heinzl, Anthi Faka, Michael Resl, Ada Trepci, Carmen Klammer, Margot Egger, Benjamin Dieplinger, Martin Clodi, Lilly Schwieler

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.

Keywords: Experimental endotoxemia; Inflammation; Kynurenine metabolites; Lipopolysaccharides (LPS).

Conflict of interest statement

All authors declare that they have no competing interests.

© 2021. The Author(s).

Figures

Fig. 1
Fig. 1
Schematic overview of the kynurenine pathway. The first and rate-limiting step is catalyzed by tryptophan 2,3-dioxygenase (TDO2) or by indoleamine 2,3-dioxygenase (IDO)1 and 2. N-formyl kynurenine is then converted by kynurenine formamidase to l-kynurenine before entering different possible branches, depending on cell-type or environmental context, to form various metabolites, which can exhibit immunological, antioxidant, or neurological activities. Pathways represented by two arrows involve several metabolites and enzymatic reactions. Nicotinamide adenine dinucleotide (NAD+)
Fig. 2
Fig. 2
Kynurenine metabolite levels after LPS (red) or placebo (blue) injection. The red line indicates the injection, the black lines the change between the three consecutive days. Data is presented as mean and standard error of the mean. *p < 0.005 (statistically significant results). KYNA: kynurenic acid, 3-HK: 3-hydroxykynurenine, QUIN: quinolinic acid
Fig. 3
Fig. 3
Ratios between metabolites after LPS (red) or placebo (blue) injection. The red line indicates the injection, the black lines the change between the three consecutive days. Data is presented as mean and standard error of the mean. *p < 0.005. KYNA: kynureninic acid, QUIN: quinolinic acid
Fig. 4
Fig. 4
Associations between A metabolite ratios and CRP or IL-6 over all timepoints. The size of the circles indicates the strength of the association (−log10p), the color indicates the direction of the association (red: positive, blue: negative). *p < 0.0083. KYNA: kynureninic acid, QUIN: quinolinic acid. B Correlation between the maximum increase in CRP (mg/dL) and the maximum increase in the kynurenine/tryptophan ratio independent of time. The black line indicates the conditional mean, and the grey area indicates the 95% confidence interval

References

    1. Schletter J, Heine H, Ulmer AJ, Rietschel ET. Molecular mechanisms of endotoxin activity. Arch Microbiol. 1995;164(6):383–389. doi: 10.1007/BF02529735.
    1. Ulevitch RJ, Tobias PS. Receptor-dependent mechanisms of cell stimulation by bacterial endotoxin. Annu Rev Immunol. 1995;13(1):437–457. doi: 10.1146/annurev.iy.13.040195.002253.
    1. Suffredini AF, Noveck RJ. Human endotoxin administration as an experimental model in drug development. Clin Pharmacol Ther. 2014;96(4):418–422. doi: 10.1038/clpt.2014.146.
    1. Henderson AJ, Lasselin J, Lekander M, Olsson MJ, Powis SJ, Axelsson J, Perrett DI. Skin colour changes during experimentally-induced sickness. Brain Behav Immun. 2017;60:312–318. doi: 10.1016/j.bbi.2016.11.008.
    1. Karshikoff B, Jensen KB, Kosek E, Kalpouzos G, Soop A, Ingvar M, Olgart Höglund C, Lekander M, Axelsson J. Why sickness hurts: A central mechanism for pain induced by peripheral inflammation. Brain Behav Immun. 2016;57:38–46. doi: 10.1016/j.bbi.2016.04.001.
    1. Lasselin J, Karshikoff B, Axelsson J, Åkerstedt T, Benson S, Engler H, Schedlowski M, Jones M, Lekander M, Andreasson A. Fatigue and sleepiness responses to experimental inflammation and exploratory analysis of the effect of baseline inflammation in healthy humans. Brain Behav Immun. 2020;83:309–314. doi: 10.1016/j.bbi.2019.10.020.
    1. Regenbogen C, Axelsson J, Lasselin J, Porada DK, Sundelin T, Peter MG, Lekander M, Lundström JN, Olsson MJ. Behavioral and neural correlates to multisensory detection of sick humans. Proc Natl Acad Sci U S A. 2017;114(24):6400–6405. doi: 10.1073/pnas.1617357114.
    1. Sundelin T, Karshikoff B, Axelsson E, Höglund CO, Lekander M, Axelsson J. Sick man walking: Perception of health status from body motion. Brain Behav Immun. 2015;48:53–56. doi: 10.1016/j.bbi.2015.03.007.
    1. Cho JH-J, Irwin MR, Eisenberger NI, Lamkin DM, Cole SW. Transcriptomic predictors of inflammation-induced depressed mood. Neuropsychopharmacology. 2019;44(5):923–929. doi: 10.1038/s41386-019-0316-9.
    1. Eisenberger NI, Berkman ET, Inagaki TK, Rameson LT, Mashal NM, Irwin MR. Inflammation-induced anhedonia: endotoxin reduces ventral striatum responses to reward. Biol Psychiatry. 2010;68(8):748–754. doi: 10.1016/j.biopsych.2010.06.010.
    1. Irwin MR, Cole S, Olmstead R, Breen EC, Cho JJ, Moieni M, Eisenberger NI. Moderators for depressed mood and systemic and transcriptional inflammatory responses: a randomized controlled trial of endotoxin. Neuropsychopharmacology. 2019;44(3):635–641. doi: 10.1038/s41386-018-0259-6.
    1. Kruse JL, Cho JH-J, Olmstead R, Hwang L, Faull K, Eisenberger NI, Irwin MR. Kynurenine metabolism and inflammation-induced depressed mood: a human experimental study. Psychoneuroendocrinology. 2019;109:104371. doi: 10.1016/j.psyneuen.2019.104371.
    1. Karshikoff B, Lekander M, Soop A, Lindstedt F, Ingvar M, Kosek E, Olgart Höglund C, Axelsson J. Modality and sex differences in pain sensitivity during human endotoxemia. Brain Behav Immun. 2015;46:35–43. doi: 10.1016/j.bbi.2014.11.014.
    1. Lasselin J, Treadway MT, Lacourt TE, Soop A, Olsson MJ, Karshikoff B, Paues-Göranson S, Axelsson J, Dantzer R, Lekander M. Lipopolysaccharide Alters Motivated Behavior in a Monetary Reward Task: a Randomized Trial. Neuropsychopharmacology. 2017;42(4):801–810. doi: 10.1038/npp.2016.191.
    1. Schedlowski M, Engler H, Grigoleit J-S. Endotoxin-induced experimental systemic inflammation in humans: a model to disentangle immune-to-brain communication. Brain Behav Immun. 2014;35:1–8. doi: 10.1016/j.bbi.2013.09.015.
    1. Schwarcz R, Bruno JP, Muchowski PJ, Wu H-Q. Kynurenines in the mammalian brain: when physiology meets pathology. Nat Rev Neurosci. 2012;13(7):465–477. doi: 10.1038/nrn3257.
    1. Hayaishi O. My life with tryptophan--never a dull moment. Protein Sci. 1993;2(3):472–475. doi: 10.1002/pro.5560020320.
    1. Hayaishi O. Properties and function of indoleamine 2,3-dioxygenase. J Biochem. 1976;79(4):13P–21P. doi: 10.1093/oxfordjournals.jbchem.a131115.
    1. Campbell B, Charych E, Lee A, Möller T. Kynurenines in CNS disease: regulation by inflammatory cytokines. Front Neurosci. 2014;8:12. doi: 10.3389/fnins.2014.00012.
    1. Walker AK, Budac DP, Bisulco S, Lee AW, Smith RA, Beenders B, Kelley KW, Dantzer R. NMDA receptor blockade by ketamine abrogates lipopolysaccharide-induced depressive-like behavior in C57BL/6J mice. Neuropsychopharmacology. 2013;38(9):1609–1616. doi: 10.1038/npp.2013.71.
    1. Sellgren CM, Kegel ME, Bergen SE, Ekman CJ, Olsson S, Larsson M, Vawter MP, Backlund L, Sullivan PF, Sklar P, Smoller JW, Magnusson PK, Hultman CM, Walther-Jallow L, Svensson CI, Lichtenstein P, Schalling M, Engberg G, Erhardt S, Landén M. A genome-wide association study of kynurenic acid in cerebrospinal fluid: implications for psychosis and cognitive impairment in bipolar disorder. Mol Psychiatry. 2015;21(10):1342–1350. doi: 10.1038/mp.2015.186.
    1. Urata Y, Koga K, Hirota Y, Akiyama I, Izumi G, Takamura M, Nagai M, Harada M, Hirata T, Yoshino O, Kawana K, Fujii T, Osuga Y. IL-1β increases expression of tryptophan 2,3-dioxygenase and stimulates tryptophan catabolism in endometrioma stromal cells. Am J Reprod Immunol. 2014;72(5):496–503. doi: 10.1111/aji.12282.
    1. Mándi Y, Vécsei L. The kynurenine system and immunoregulation. J Neural Transm. 2012;119(2):197–209. doi: 10.1007/s00702-011-0681-y.
    1. Robinson CM, Hale PT, Carlin JM. The role of IFN-gamma and TNF-alpha-responsive regulatory elements in the synergistic induction of indoleamine dioxygenase. J Interferon Cytokine Res. 2005;25(1):20–30. doi: 10.1089/jir.2005.25.20.
    1. Robinson CM, Shirey KA, Carlin JM. Synergistic transcriptional activation of indoleamine dioxygenase by IFN-gamma and tumor necrosis factor-alpha. J Interferon Cytokine Res. 2003;23(8):413–421. doi: 10.1089/107999003322277829.
    1. Nasef A, Chapel A, Mazurier C, Bouchet S, Lopez M, Mathieu N, Sensebé L, Zhang Y, Gorin NC, Thierry D, Fouillard L. Identification of IL-10 and TGF-beta transcripts involved in the inhibition of T-lymphocyte proliferation during cell contact with human mesenchymal stem cells. Gene Expr. 2007;13(4-5):217–226. doi: 10.3727/000000006780666957.
    1. Hu B, Hissong BD, Carlin JM. Interleukin-1 Enhances Indoleamine 2,3-Dioxygenase Activity by Increasing Specific mRNA Expression in Human Mononuclear Phagocytes. J Interferon Cytokine Res. 1995;15(7):617–624. doi: 10.1089/jir.1995.15.617.
    1. Brown RR, Lee CM, Kohler PC, Hank JA, Storer BE, Sondel PM. Altered tryptophan and neopterin metabolism in cancer patients treated with recombinant interleukin 2. Cancer Res. 1989;49(17):4941–4.
    1. Litzenburger UM, Opitz CA, Sahm F, Rauschenbach KJ, Trump S, Winter M, Ott M, Ochs K, Lutz C, Liu X, Anastasov N, Lehmann I, Höfer T, von Deimling A, Wick W, Platten M. Constitutive IDO expression in human cancer is sustained by an autocrine signaling loop involving IL-6, STAT3 and the AHR. Oncotarget. 2014;5(4):1038–1051. doi: 10.18632/oncotarget.1637.
    1. Carbotti G, Barisione G, Airoldi I, Mezzanzanica D, Bagnoli M, Ferrero S, Petretto A, Fabbi M, Ferrini S. IL-27 induces the expression of IDO and PD-L1 in human cancer cells. Oncotarget. 2015;6(41):43267–43280. doi: 10.18632/oncotarget.6530.
    1. Yanagawa Y, Iwabuchi K, Onoé K. Co-operative action of interleukin-10 and interferon-gamma to regulate dendritic cell functions. Immunology. 2009;127(3):345–353. doi: 10.1111/j.1365-2567.2008.02986.x.
    1. Chon SY, Hassanain HH, Gupta SL. Cooperative role of interferon regulatory factor 1 and p91 (STAT1) response elements in interferon-gamma-inducible expression of human indoleamine 2,3-dioxygenase gene. J Biol Chem. 1996;271(29):17247–17252. doi: 10.1074/jbc.271.29.17247.
    1. Cerávolo IP, Chaves AC, Bonjardim CA, Sibley D, Romanha AJ, Gazzinelli RT. Replication of Toxoplasma gondii, but not Trypanosoma cruzi, is regulated in human fibroblasts activated with gamma interferon: requirement of a functional JAK/STAT pathway. Infect Immun. 1999;67(5):2233–2240. doi: 10.1128/IAI.67.5.2233-2240.1999.
    1. Kudo T, Prentzell MT, Mohapatra SR, Sahm F, Zhao Z, Grummt I, Wick W, Opitz CA, Platten M, Green EW. Constitutive Expression of the Immunosuppressive Tryptophan Dioxygenase TDO2 in Glioblastoma Is Driven by the Transcription Factor C/EBPβ. Front Immunol. 2020;11:657. doi: 10.3389/fimmu.2020.00657.
    1. Munn DH, Mellor AL. IDO in the Tumor Microenvironment: Inflammation, Counter-Regulation, and Tolerance. Trends Immunol. 2016;37(3):193–207. doi: 10.1016/j.it.2016.01.002.
    1. Lee GK, Park HJ, Macleod M, Chandler P, Munn DH, Mellor AL. Tryptophan deprivation sensitizes activated T cells to apoptosis prior to cell division. Immunology. 2002;107(4):452–460. doi: 10.1046/j.1365-2567.2002.01526.x.
    1. Stone TW, Forrest CM, Mackay GM, Stoy NL, Darlington G. Tryptophan, adenosine, neurodegeneration and neuroprotection. Metab Brain Dis. 2007;22(3–4):337–52. doi: 10.1007/s11011-007-9064-3.
    1. Hilmas C, Pereira EFR, Alkondon M, Rassoulpour A, Schwarcz R, Albuquerque EX. The Brain Metabolite Kynurenic Acid Inhibits α7 Nicotinic Receptor Activity and Increases Non-α7 Nicotinic Receptor Expression: Physiopathological Implications. J Neurosci. 2001;21(19):7463–73. doi: 10.1523/JNEUROSCI.21-19-07463.2001.
    1. Stone TW. Neuropharmacology of Quinolinic and Kynurenic Acids. Pharmacol Rev. 1993;45(3):309–79.
    1. Guillemin GJ, Smith DG, Smythe GA, Armati PJ, Brew BJ. Expression of the Kynurenine Pathway Enzymes in Human Microglia and Macrophages. Adv Exp Med Biol. 2003;527:105–12. doi: 10.1007/978-1-4615-0135-0_12.
    1. Guillemin GJ. Quinolinic acid: neurotoxicity. FEBS J. 2012;279(8):1355–1355. doi: 10.1111/j.1742-4658.2012.08493.x.
    1. Dantzer R, O’Connor JC, Freund GG, Johnson RW, Kelley KW. From inflammation to sickness and depression: when the immune system subjugates the brain. Nat Rev Neurosci. 2008;9(1):46–56. doi: 10.1038/nrn2297.
    1. Dostal CR, Gamsby NS, Lawson MA, McCusker RH. Glia- and tissue-specific changes in the Kynurenine Pathway after treatment of mice with lipopolysaccharide and dexamethasone. Brain Behav Immun. 2018;69:321–335. doi: 10.1016/j.bbi.2017.12.006.
    1. O’Connor JC, Lawson MA, André C, Moreau M, Lestage J, Castanon N, et al. Lipopolysaccharide-induced depressive-like behavior is mediated by indoleamine 2,3-dioxygenase activation in mice. Mol Psychiatry. 2009;14(5):511–522. doi: 10.1038/sj.mp.4002148.
    1. Imbeault S, Goiny M, Liu X, Erhardt S. Effects of IDO1 and TDO2 inhibition on cognitive deficits and anxiety following LPS-induced neuroinflammation. Acta Neuropsychiatr. 2020;32(1):43–53. doi: 10.1017/neu.2019.44.
    1. Oliveros A, Wininger K, Sens J, Larsson MK, Liu XC, Choi S, Faka A, Schwieler L, Engberg G, Erhardt S, Choi DS. LPS-induced cortical kynurenic acid and neurogranin-NFAT signaling is associated with deficits in stimulus processing during Pavlovian conditioning. J Neuroimmunol. 2017;313:1–9. doi: 10.1016/j.jneuroim.2017.09.010.
    1. Tufvesson-Alm M, Imbeault S, Liu X-C, Zheng Y, Faka A, Choi D-S, Schwieler L, Engberg G, Erhardt S. Repeated administration of LPS exaggerates amphetamine-induced locomotor response and causes learning deficits in mice. J Neuroimmunol. 2020;349:577401. doi: 10.1016/j.jneuroim.2020.577401.
    1. Savitz J. The kynurenine pathway: a finger in every pie. Mol Psychiatry. 2020;25(1):131–147. doi: 10.1038/s41380-019-0414-4.
    1. Stone TW, Darlington LG. The kynurenine pathway as a therapeutic target in cognitive and neurodegenerative disorders. Br J Pharmacol. 2013;169(6):1211–27. doi: 10.1111/bph.12230.
    1. Heinzl MW, Resl M, Klammer C, Egger M, Dieplinger B, Clodi M. Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) is not induced in artificial human inflammation and is not correlated with inflammatory response. Infect Immun. 2020;88(3). Available from: .
    1. Schwieler L, Trepci A, Krzyzanowski S, Hermansson S, Granqvist M, Piehl F, Venckunas T, Brazaitis M, Kamandulis S, Lindqvist D, Jones AD, Erhardt S, Brundin L. A novel, robust method for quantification of multiple kynurenine pathway metabolites in the cerebrospinal fluid. Bioanalysis. 2020;12(6):379–392. doi: 10.4155/bio-2019-0303.
    1. Cheverud JM. A simple correction for multiple comparisons in interval mapping genome scans. Heredity. 2001;87(Pt 1):52–58. doi: 10.1046/j.1365-2540.2001.00901.x.
    1. Nyholt DR. A simple correction for multiple testing for single-nucleotide polymorphisms in linkage disequilibrium with each other. Am J Hum Genet. 2004;74(4):765–769. doi: 10.1086/383251.
    1. Cinar O, Viechtbauer W. poolr: Methods for pooling p-values from (dependent) tests. 2020. Available from:
    1. R Core Team. R: A language and environment for statistical computing. Vienna: R Foundation for Statistical Computing; 2020. /.
    1. Pinheiro J, Bates D, DebRoy S, Sarkar D, R Core team. nlme: Linear and Nonlinear Mixed Effects Models. 2021; Available from:
    1. Wickham H. ggplot2: elegant graphics for data analysis. New York: Springer-Verlag; 2016.
    1. Felger JC, Haroon E, Patel TA, Goldsmith DR, Wommack EC, Woolwine BJ, le NA, Feinberg R, Tansey MG, Miller AH. What does plasma CRP tell us about peripheral and central inflammation in depression? Mol Psychiatry. 2020;25(6):1301–1311. doi: 10.1038/s41380-018-0096-3.
    1. Padberg J-S, Van Meurs M, Kielstein JT, Martens-Lobenhoffer J, Bode-Böger SM, Zijlstra JG, et al. Indoleamine-2,3-dioxygenase activity in experimental human endotoxemia. Exp Transl Stroke Med. 2012;4(1):24. doi: 10.1186/2040-7378-4-24.
    1. Hunt C, Macedo E, Cordeiro T, Suchting R, de Dios C, Cuellar Leal VA, Soares JC, et al. Effect of immune activation on the kynurenine pathway and depression symptoms - A systematic review and meta-analysis. Neurosci Biobehav Rev. 2020;118:514–523. doi: 10.1016/j.neubiorev.2020.08.010.
    1. Lawson MA, Parrott JM, McCusker RH, Dantzer R, Kelley KW, O’Connor JC. Intracerebroventricular administration of lipopolysaccharide induces indoleamine-2,3-dioxygenase-dependent depression-like behaviors. J Neuroinflammation. 2013;10:87.
    1. Sakurai M, Yamamoto Y, Kanayama N, Hasegawa M, Mouri A, Takemura M, et al. Serum metabolic profiles of the tryptophan-kynurenine pathway in the high risk subjects of major depressive disorder. Sci Rep. 2020;10(1):1–13. doi: 10.1038/s41598-019-56847-4.
    1. Liu H, Ding L, Zhang H, Mellor D, Wu H, Zhao D, Wu C, Lin Z, Yuan J, Peng D. The metabolic factor kynurenic acid of kynurenine pathway predicts major depressive disorder. Front Psychiatry. 2018;9:552. doi: 10.3389/fpsyt.2018.00552.
    1. Molteni R, Macchi F, Zecchillo C, Dell’agli M, Colombo E, Calabrese F, et al. Modulation of the inflammatory response in rats chronically treated with the antidepressant agomelatine. Eur Neuropsychopharmacol. 2013;23(11):1645–1655. doi: 10.1016/j.euroneuro.2013.03.008.
    1. Erhardt S, Schwieler L, Imbeault S, Engberg G. The kynurenine pathway in schizophrenia and bipolar disorder. Neuropharmacology. 2017;112(Pt B):297–306. doi: 10.1016/j.neuropharm.2016.05.020.
    1. Badawy AA-B. Hypothesis kynurenic and quinolinic acids: the main players of the kynurenine pathway and opponents in inflammatory disease. Med Hypotheses. 2018;118:129–138. doi: 10.1016/j.mehy.2018.06.021.

Source: PubMed

Sponsors and Collaborators

Medical Conditions

Drug Interventions

3
Subscribe