Cited by 551Tryptophan and brain disordersAmino Acid Enzymes and MetabolismReproductive System and Pregnancy

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Monitoring tryptophan metabolism in chronic immune activation

Schröcksnadel, Katharina, Wirleitner, Barbara, Winkler, Christiana, Fuchs, Dietmar·2006·Clinica Chimica Acta

DOI 10.1016/j.cca.2005.06.013

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Abstract

The essential amino acid tryptophan is a constituent of proteins and is also a substrate for two important biosynthetic pathways: the generation of neurotransmitter 5-hydroxytryptamine (serotonin) by tryptophan 5-hydroxylase, and the formation of kynurenine derivatives and nicotinamide adenine dinucleotides. The latter pathway is initiated by the enzymes tryptophan pyrrolase (tryptophan 2,3-dioxygenase, TDO) and indoleamine 2,3-dioxygenase (IDO). TDO is located in liver cells, whereas IDO is expressed in a variety of cells including monocyte-derived macrophages and dendritic cells and is preferentially induced by Th1-type cytokine interferon-gamma. Tryptophan depletion via IDO is part of the cytostatic and antiproliferative activity mediated by interferon-gamma in cells. In vivo tryptophan concentration can be measured by HPLC by monitoring its natural fluorescence (285 nm excitation and 365 nm emission wavelength). IDO activity is characterized best by the kynurenine to tryptophan ratio which correlates with concentrations of immune activation markers such as neopterin. Low serum/plasma tryptophan concentration is observed in infectious, autoimmune, and malignant diseases and disorders that involve cellular (Th1-type) immune activation as well as during pregnancy due to accelerated tryptophan conversion. Thus, in states of persistent immune activation, low tryptophan concentration may contribute to immunodeficiency. Decreased serum tryptophan can also effect serotonin biosyn…

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“Tryptophan degradation by IDO was found to be necessary for induction of tolerance to the fetus [51].”
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Barichello, T., Milioli, G., Generoso, J. S., Cipriano, A. L., da Costa, C. S., Moreira, A. P., Vilela, M. C., Comim, C. M., Teixeira, A. L., & Quevedo, J. (2011) · Journal of Neural Transmission · doi:10.1007/s00702-011-0749-8 · Cited by 14
Picolinic Acid in Patients with Chronic Hepatitis C Infection: A Preliminary Report
Zuwała−Jagiełło, J., Pazgan−Simon, M., Simon, K. A., & Warwas, M. (2012) · Mediators of Inflammation · doi:10.1155/2012/762863 · Cited by 13
“In particular, the ratio of kynurenine to tryptophan (KYN/TRP) seems to be a sensitive indicator for interferon-γ-induced tryptophan degradation (reviewed in [18]).”
Background
Kynurenine pathway can be a potential biomarker of fatigue in primary Sjögren's syndrome.
Park, Y., Lee, J., Koh, J., Kim, M.-J., Park, S.-H., & Kwok, S.-K. (2022) · Clinical and Experimental Rheumatology · doi:10.55563/clinexprheumatol/cp4st9 · Cited by 13
“Several studies have reported that IDO1 activity, represented by the ratio of kynurenine to tryptophan, and kynurenine metabolites are increased and correlated with fatigue in patients with systemic lupus erythematosus and rheumatoid arthritis (16, 17).”
Background
Age-Associated Gut Dysbiosis, Marked by Loss of Butyrogenic Potential, Correlates With Altered Plasma Tryptophan Metabolites in Older People Living With HIV
Ghare, S. S., Singhal, R. A., Bryant, V. E., Gautam, S., Tirumala, C. C., Srisailam, P., Reyes-Vega, A., Ghooray, D. T., McClain, C. J., Hoffman, K. L., et al. (2022) · JAIDS Journal of Acquired Immune Deficiency Syndromes · doi:10.1097/qai.0000000000002866 · Cited by 16
Young Plasma Induces Antidepressant-Like Effects in Aged Rats Subjected to Chronic Mild Stress by Suppressing Indoleamine 2,3-Dioxygenase Enzyme and Kynurenine Pathway in the Prefrontal Cortex
Ghaffari‐Nasab, A., Badalzadeh, R., Mohaddes, G., Javani, G., Kalan, A. E., & Alipour, M. R. (2021) · Neurochemical Research · doi:10.1007/s11064-021-03440-9 · Cited by 16
EWS‐FLI1 impairs aryl hydrocarbon receptor activation by blocking tryptophan breakdown via the kynurenine pathway
Mutz, C. N., Schwentner, R., Kauer, M., Katschnig, A. M., Kromp, F., Aryee, D., Erhardt, S., Goiny, M., Alonso, J., Fuchs, D., et al. (2016) · FEBS Letters · doi:10.1002/1873-3468.12243 · Cited by 13
Self-citation
Raman spectroscopy detects melanoma and the tissue surrounding melanoma using tissue-engineered melanoma models
Yorucu, C., Lau, K., Mittar, S., Green, N. H., Raza, A., Rehman, I. U., & MacNeil, S. (2015) · Applied Spectroscopy Reviews · doi:10.1080/05704928.2015.1126840 · Cited by 16
Immunomodulatory effects in vitro of vitamin K antagonist acenocoumarol.
Schroecksnadel, S., Gostner, J., Jenny, M., Kurz, K., Schennach, H., Weiss, G., & Fuchs, D. (2013) · Thrombosis Research · doi:10.1016/j.thromres.2013.02.012 · Cited by 13
“, HIV infection, malignancy and autoimmune syndromes, increased neopterin concentrations are closely associated with higher kynurenine to tryptophan ratios (Kyn/Trp), and elevated neopterin levels and accelerated tryptophan breakdown reflect the course of disease and are predictive for an unfavourable outcome [7,15,16…”
BackgroundSelf-citation
Neopterin production and tryptophan degradation during 24-months therapy with interferon beta-1a in multiple sclerosis patients
Durastanti, V., Lugaresi, A., Bramanti, P., Amato, M., Bellantonio, P., Luca, G. D., Picconi, O., Fantozzi, R., Locatelli, L., Soldà, A., et al. (2011) · Journal of Translational Medicine · doi:10.1186/1479-5876-9-42 · Cited by 13
“The kyn/trp ratio provides an estimate of IDO activity and correlates with markers of IFNg immune activation, like neopterin [8,12].”
Background
Altered monoaminergic transporter binding in hepatitis C related cerebral dysfunction: a neuroimmunologial condition?
Forton, D. M. (2006) · Gut · doi:10.1136/gut.2006.100081 · Cited by 18
The Interactions Between Kynurenine, Folate, Methionine and Pteridine Pathways in Obesity.
Engin, A., & Engin, A. (2017) · Advances in Experimental Medicine and Biology · doi:10.1007/978-3-319-48382-5_22 · Cited by 13
High Rate of Deficiency in the Amino Acids Tryptophan and Histidine in People with Wounds: Implication for Nutrient Targeting in Wound Management-A Pilot Study
Dawson, B., & Favaloro, E. J. (2009) · Advances in Skin & Wound Care · doi:10.1097/01.asw.0000345280.20779.17 · Cited by 12
“2,3-dioxygenase is induced by cytokines, to facilitate the degradation of tryptophan via the kynurenine pathway.(12) If this is the cause of the decreased level of tryptophan, then increasing B group vitamins (B3 in particular) or providing a diet rich in omega-3 fatty acids may lessen the degradation and allow increa…”
Background
Artemisia argyi essential oil alleviates asthma by regulating 5-LOX-CysLTs and IDO-1-KYN pathway: insights from metabolomics.
Rong, Y., Tang, M., Liu, L., Ma, X.-G., Liu, M., Qu, L., Liao, X., Jiang, Q., Zhang, N., & Xu, X. (2024) · Journal of Ethnopharmacology · doi:10.1016/j.jep.2024.118458 · Cited by 12
Indoleamine 2, 3-dioxygenase 1 inhibitory compounds from natural sources
Tan, Y., Liu, M., Li, M., Chen, Y., & Ren, M. (2022) · Frontiers in Pharmacology · doi:10.3389/fphar.2022.1046818 · Cited by 14
“Interestingly, an imbalance in the Kyn/Trp ratio is often observed in inflammation-related disease, including infections and autoimmune disorders (Schröcksnadel et al., 2006; Huang et al., 2020).”
Background
Nicotinamide adenine dinucleotide metabolism: driving or counterbalancing inflammatory bowel disease?
Xue, X., Miao, Y., & Wei, Z. (2022) · FEBS Letters · doi:10.1002/1873-3468.14528 · Cited by 14
Serum Concentration of the Phytohormone Abscisic Acid Is Associated With Immune-Regulatory Mediators and Is a Potential Biomarker of Disease Severity in Chronic Obstructive Pulmonary Disease
Hoang, Q. T. M., Nguyễn, V. K., Oberacher, H., Fuchs, D., Hernandez-Vargas, E. A., Borucki, K., Waldburg, N., Wippermann, J., Schreiber, J., Bruder, D., et al. (2021) · Frontiers in Medicine · doi:10.3389/fmed.2021.676058 · Cited by 14
“We noticed an increase in serum IDO activity in our COPD cohort (Figure 4), which might be stimulated by IFN-γ or other pro-inflammatory cytokines (70) that are released in consequence of ongoing lung inflammation (71).”
BackgroundSelf-citation
Associations of neopterin and kynurenine–tryptophan ratio with survival in primary sclerosing cholangitis
Dhillon, A. K., Rupp, C., Bergquist, A. M., Voitl, R., Folseraas, T., Trøseid, M., Midttun, Ø., Ueland, P. M., Karlsen, T. H., Vesterhus, M. N., et al. (2021) · Scandinavian Journal of Gastroenterology · doi:10.1080/00365521.2021.1880627 · Cited by 13
“Speaking against that being the case, KT-ratio were similar in the cohorts and the well-known strong correlation between KT-ratio and neopterin, [27] was observed in all cohorts, despite neopterin, kynurenine and tryptophan having different biochemical characteristics including more stable concentrations during storag…”
Result
Simultaneous analysis of neopterin, kynurenine and tryptophan by amine-HPLC shows minor oxidative stress from short-term exhaustion exercise
Baxter-Parker, G., Chu, A., Petocz, P., Samman, S., & Gieseg, S. (2019) · Pteridines · doi:10.1515/pteridines-2019-0003 · Cited by 12
“IDO activation is associated with increased inflammation and disease progression [13, 14].”
Background
Long-term significance of urinary neopterin in ovarian cancer: a study by the Austrian Association for Gynecologic Oncology (AGO).
Volgger, B., Windbichler, G., Zeimet, A., Graf, A., Bogner, G., Angleitner-Boubenizek, L., Rohde, M., Denison, U., Sliutz, G., Fuith, L., et al. (2016) · Annals of Oncology · doi:10.1093/annonc/mdw248 · Cited by 12
Self-citation
Immunological alterations in individuals exposed to metal(loid)s in the Panasqueira mining area, Central Portugal
Coelho, P., García-Léston, J., Costa, S., Costa, C., Silva, S., Fuchs, D., Geisler, S., Dall’Armi, V., Zoffoli, R., Bonassi, S., et al. (2014) · The Science of The Total Environment · doi:10.1016/j.scitotenv.2013.12.093 · Cited by 12
“In humans, an increased formation of neopterin and enhanced breakdown of tryptophan have been found in viral infections, malignant disorders and autoimmune diseases (Schroecksnadel et al., 2006).”
BackgroundInfluentialSelf-citation
Mechanisms of the effect of gut microbes on depression through the microbiota-gut-brain axis
Zhou, X., Wang, S., Wang, X., Chen, X., Zhou, P., Ma, K., & Zhang, P. (2025) · Frontiers in Nutrition · doi:10.3389/fnut.2025.1634548 · Cited by 14
Exploring environmental exposomes and the gut-brain nexus: Unveiling the impact of pesticide exposure
Khoo, S. C., Zhang, N., Luang‐In, V., Goh, M. S., Sonne, C., & Ling, N. (2024) · Environmental Research · doi:10.1016/j.envres.2024.118441 · Cited by 13
Does smoking influence tryptophan metabolism in periodontal inflammation? A cross-sectional study.
Önder, C., Akdoğan, N., Kurgan, Ş., Balcı, N., Serdar, C. C., Serdar, M., & Günhan, M. (2023) · Journal of Periodontal Research · doi:10.1111/jre.13166 · Cited by 11
Changes in Tryptophan-Kynurenine Metabolism in Patients with Depression Undergoing ECT—A Systematic Review
Aarsland, T. I. M., Instanes, J. T., Posserud, M.-B. R., Ulvik, A., Keßler, U., & Haavik, J. (2022) · Pharmaceuticals · doi:10.3390/ph15111439 · Cited by 13
“Inflammation Reduced levels of Trp and increased levels of kynurenines have been demonstrated in a range of clinical conditions involving immune activation, including infection, autoimmune disorders, cancer, neurodegenerative diseases and more (reviewed in [93,94]).”
Background
Tryptophan‐kynurenine metabolism during acute alcohol withdrawal in patients with alcohol use disorder: The role of immune activation
Mechtcheriakov, S., von Gleissenthall, G., Geisler, S., Arnhard, K., Oberacher, H., Schurr, T., Kemmler, G., Unterberger, C., & Fuchs, D. (2022) · Alcoholism Clinical and Experimental Research · doi:10.1111/acer.14920 · Cited by 12
“Under normal conditions, the IDO- 1 degrades approximately 5% to 15% of TRP but it can be considerably activated by cytokines (Schröcksnadel et al., 2006).”
BackgroundSelf-citation
Effect of a Single Bout of Aerobic Exercise on Kynurenine Pathway Metabolites and Inflammatory Markers in Prostate Cancer Patients—A Pilot Randomized Controlled Trial
Schenk, A., Esser, T., Knoop, A., Thevis, M., Herden, J., Heidenreich, A., Bloch, W., Joisten, N., & Zimmer, P. (2020) · Metabolites · doi:10.3390/metabo11010004 · Cited by 13
“KYN downstream metabolites and the KYN/TRP ratio are relevant biomarkers in diseases associated with chronic excesses or inflammation, including prostate cancer [51,52].”
Background
Immune Activation and Anemia Are Associated with Decreased Quality of Life in Patients with Solid Tumors
Kink, P., Egger, E., Lanser, L., Klaunzner, M., Holzner, B., Willenbacher, W., Kasseroler, M. T., Fuchs, D., Weiss, G., & Kurz, K. (2020) · Journal of Clinical Medicine · doi:10.3390/jcm9103248 · Cited by 11
“Within T-helper cell type 1 (Th1), immune response to the pro-inflammatory cytokine interferon-γ (IFN-γ) induces the enzyme indoleamine 2,3-dioxygenase-1 (IDO) to degrade tryptophan to kynurenine (Kyn) [17,18].”
BackgroundSelf-citation
Serum indoleamine 2,3 dioxygenase and tryptophan and kynurenine ratio using the UPLC-MS/MS method, in patients undergoing peritoneal dialysis, hemodialysis, and kidney transplantation
Yilmaz, N., Ustundağ, Y., Kıvrak, Ş., Kahvecioğlu, S., Celik, H., Kıvrak, İ., & Huysal, K. (2016) · Renal Failure · doi:10.1080/0886022x.2016.1209389 · Cited by 11
“Tryptophan and kynurenine levels provide information about IDO activity, which may inhibit activation and proliferation of T cells, natural killer cells, total lymphocytes, and monocytes.(7) In addition, IDO may play a critical role in the immunomodulatory enzymes that provide immunosuppression in several diseases, su…”
Background
Bioactivites of two common polyphenolic compounds: Verbascoside and catechin
Si̇pahi̇, H., Gostner, J. M., Becker, K., Charehsaz, M., Kırmızıbekmez, H., Schennach, H., Aydın, A., & Fuchs, D. (2015) · Pharmaceutical Biology · doi:10.3109/13880209.2015.1072830 · Cited by 17
“…and tryptophan breakdown are well characterized as markers of immune activation in humans, which are closely associated with the course of clinical conditions like infections, malignant diseases, and autoimmune pathologies (Murr et al., 2002; Schroecksnadel et al., 2006; Taylor & Feng, 1991).”
BackgroundSelf-citation
Article Commentary: Kynurenine Pathway Pathologies: Do Nicotinamide and Other Pathway Co-Factors have a Therapeutic Role in Reduction of Symptom Severity, Including Chronic Fatigue Syndrome (CFS) and Fibromyalgia (FM)
Blankfield, A. (2013) · International Journal of Tryptophan Research · doi:10.4137/ijtr.s11193 · Cited by 12
A Pilot Study on Neopterin Levels and Tryptophan Degradation in Zinc-Exposed Galvanization Workers
Saraç, E., Girgin, G., Palabıyık, Ş. S., Charehsaz, M., Aydın, A., Şahin, G., & Baydar, T. (2012) · Biological Trace Element Research · doi:10.1007/s12011-012-9569-4 · Cited by 17
“circumstances [35–39].”
Interferon-gamma Mediated Metabolic Pathways in Hospitalized Patients During Acute and Reconvalescent COVID-19
Gietl, M., Burkert, F. R., Seiwald, S., Boehm, A., Hofer, S., Gostner, J. M., Piater, T., Geisler, S., Weiß, G., Löffler‐Ragg, J., et al. (2023) · International Journal of Tryptophan Research · doi:10.1177/11786469231154244 · Cited by 16
Self-citation
Study on antidepressant mechanism of Radix Bupleuri–Radix Paeoniae Alba herb pair by metabonomics combined with 1H nuclear magnetic resonance and ultra-high-performance liquid chromatography-tandem mass spectrometry detection technology
Zhou, Y., Li, T., Zhu, S., Gong, W., Qin, X., & Du, G. (2021) · Journal of Pharmacy and Pharmacology · doi:10.1093/jpp/rgab061 · Cited by 10
Antidepressant effects of direct‐acting antivirals against hepatitis C virus—Results from a pilot study
Hahn, D., Stokes, C. S., Kaiser, R., Meyer, M. R., Lammert, F., & Gruenhage, F. (2018) · European Journal of Clinical Investigation · doi:10.1111/eci.13024 · Cited by 10
Urinary metabolomic study of the antagonistic effect of P. ginseng in rats with estrogen decline using ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.
Lin, H., Liu, Z.-Y., Pi, Z., Men, L.-H., Chen, W.-J., & Liu, Z.-Q. (2018) · Food & Function · doi:10.1039/c7fo01680h · Cited by 10
Hypericum Perforatum Decreased Hippocampus TNF-α and Corticosterone Levels with No Effect on Kynurenine/Tryptophan Ratio in Bilateral Ovariectomized Rats
El‐Bakly, W. M., & Hasanin, A. H. (2014) · Korean Journal of Physiology and Pharmacology · doi:10.4196/kjpp.2014.18.3.233 · Cited by 11
“Thus, an increase in the ratio reflects greater enzyme activity, a decrease indicates lower activity [32].”
Background
Specific Immunotherapy Normalizes Tryptophan Concentrations in Patients with Allergic Rhinitis
Kofler, H., Kurz, K., Grander, G., & Fuchs, D. (2012) · International Archives of Allergy and Immunology · doi:10.1159/000338937 · Cited by 10
Self-citation
Amino Acids, Peptides, and Proteins
Hortin, G. L. (2012) · Elsevier eBooks · doi:10.1016/b978-1-4160-6164-9.00021-4 · Cited by 18
Superior normalization using total protein for western blot analysis of human adipocytes
Westerberg, L. J. S., Dedic, B., Näslund, E. B., Thorell, A., & Spalding, K. L. (2025) · PLoS ONE · doi:10.1371/journal.pone.0328136 · Cited by 10
Association between small intestine bacterial overgrowth and psychiatric disorders
Bogielski, B., Michalczyk, K., Głodek, P., Tempka, B., Gębski, W., & Stygar, D. M. (2024) · Frontiers in Endocrinology · doi:10.3389/fendo.2024.1438066 · Cited by 14
“The remaining portion of kynurenine metabolism takes place in the brain, liver, and GI tract, where is catalyzed by indoleamine 2,3-dioxygenase (IDO), whose expression can be induced by cytokines, especially those released during Th1-type immune responses, radicals, and interferons (47).”
Background
Correlation between serum tryptophan metabolism and treatment efficacy of dapoxetine in patients with premature ejaculation: A pilot study
Wu, C.-L., Huang, S., Liu, Z., Wang, Y., Zhu, Y., & Zang, Z. (2024) · Andrology · doi:10.1111/andr.13632 · Cited by 11
“38 The KYN pathway can diminish serum TRP concentration by activating IDO or TDO, 39 resulting in reduced TRP availability in the brain.”
Post-partum depression: From clinical understanding to preclinical assessments
Moreira, L. K. D. S., Moreira, C. V. L., Custódio, C. H. X., Dias, M. L. P., Rosa, D. A., Neto, M. L. F., Colombari, E., Costa, É. A., Fajemiroye, J. O., & Pedrino, G. R. (2023) · Frontiers in Psychiatry · doi:10.3389/fpsyt.2023.1173635 · Cited by 10
“For instance, a report showed varying peripartum tryptophan with lower plasma concentration in the second and third trimesters as compared to the first trimester, and gradual postpartum restoration after 6 weeks (82).”
Background
Identification of activation of tryptophan–NAD+ pathway as a prominent metabolic response to thermally oxidized oil through metabolomics-guided biochemical analysis
Wang, L., Yao, D., Urriola, P. E., Hanson, A. R., Saqui–Salces, M., Kerr, B. J., Shurson, G. C., & Chen, C. (2018) · The Journal of Nutritional Biochemistry · doi:10.1016/j.jnutbio.2018.04.009 · Cited by 11
Mapping the human proteome for non-redundant peptide islands
Capone, G., Marinis, A. D., Simone, S., Kusalik, A., & Kanduc, D. (2008) · Amino Acids · doi:10.1007/s00726-007-0563-7 · Cited by 9
“…et al. (2003) Tryptophan pyrrolase P14902 32 LPDFYNDWMFIA Tryptophan chronic immune activation in neurologic= psychiatric disorders Schrocksnadel et al. (2006) Psoriasis susceptibility 1 Q5ST21 49 MEPANHFWHAGD Psoriasis Szczerkowska-Dobosz (2005); Ozawa and Aiba…”
Background
Cytokine and IDO metabolite changes effected by calcium pterin during inhibition of MDA-MB-231 xenograph tumors in nude mice.
Moheno, P. B. B., Pfleiderer, W., DiPasquale, A., Rheingold, A., & Fuchs, D. (2008) · International journal of pharmaceutics · doi:10.1016/j.ijpharm.2007.12.021 · Cited by 9
Self-citation
Effects of globularifolin on cell survival, nuclear factor-κB activity, neopterin production, tryptophan breakdown and free radicals in vitro
Si̇pahi̇, H., Becker, K., Gostner, J. M., Charehsaz, M., Kırmızıbekmez, H., Schennach, H., Aydın, A., & Fuchs, D. (2013) · Fitoterapia · doi:10.1016/j.fitote.2013.10.012 · Cited by 8
Self-citation
Increased Tryptophan Catabolism Provides Predictive Value to Chronic Heart Failure Patients with Low-Grade Inflammation
Wang, H., Wu, J., Wei, H., Zhang, Y., Wang, Y., & Wang, D. W. (2024) · Inflammation · doi:10.1007/s10753-024-02100-8 · Cited by 8
“…concentration of the tryptophan and kynurenine, the kynurenine to tryptophan ratio (KTR) is a more useful index for assessing IDO1 activity and provides a better approach than directly measuring the metabolites, which is generally accepted as a surrogate indicator of IDO catabolic activity[3, 4].”
The serum kynurenine pathway metabolic profile is associated with overweight and obesity in multiple sclerosis
Kupjetz, M., Patt, N., Joisten, N., Ueland, P. M., McCann, A., Gonzenbach, R. R., Bansi, J., & Zimmer, P. (2023) · Multiple Sclerosis and Related Disorders · doi:10.1016/j.msard.2023.104592 · Cited by 9
C-Reactive Protein in Bipolar Disorder and Unipolar Depression
Zhang, X., Li, X., Tong, J., Li, N., & Zhang, F. (2022) · The Journal of Nervous and Mental Disease · doi:10.1097/nmd.0000000000001487 · Cited by 9
“Recent studies have suggested that inflammation may contribute to the development of BD (Maes, 2011; Müller and Schwarz, 2007; Schiepers et al., 2005; Schröcksnadel et al., 2006).”
Background
A prospective study of pre-diagnostic circulating tryptophan and kynurenine, and the kynurenine/tryptophan ratio and risk of glioma
Samanic, C. M., Yue, Y., Coté, D. J., Stampfer, M. J., Wang, M., McCann, A., Midttun, Ø., Ueland, P. M., Smith‐Warner, S. A., & Egan, K. M. (2021) · Cancer Epidemiology · doi:10.1016/j.canep.2021.102075 · Cited by 8
Metabolomics-Based Clinical Efficacy of Compound Shenlu Granule, a Chinese Patent Medicine, in the Supportive Management of Aplastic Anemia Patients: A Randomized Controlled Pilot Trial
Feng, Z., Hu, X.-Y., Qu, W.-Y., Zhu, X.-Q., Lu, J.-Y., Huang, Z.-D., Zhao, L., & Chen, P. (2021) · Evidence-Based Complementary and Alternative Medicine · doi:10.1155/2021/6655848 · Cited by 8
“Tryptophan can be involved in different pathways, including the kynurenine pathway, which has been reported to be regulated by altered immune responses [25].”
Background
Review of 10 years of research on breast cancer patients: Focus on indoleamine 2,3-dioxygenase
Asghar, K., Farooq, A., Zulfiqar, B., & Loya, A. (2021) · World Journal of Clinical Oncology · doi:10.5306/wjco.v12.i6.429 · Cited by 8
The plasma metabolic profiling of chronic acephate exposure in rats via an ultra-performance liquid chromatography-mass spectrometry based metabonomic method.
Hou, Y., Cao, C., Bao, W., Yang, S., Shi, H., Hao, D., Zhao, X.-J., & Wu, Y.-H. (2015) · Molecular Biosystems · doi:10.1039/c4mb00523f · Cited by 8
Cytokine-Induced Sickness Behavior and Depression
Chang, Q., Szegedi, S. S., O’Connor, J. C., Dantzer, R., & Kelley, K. W. (2008) · Springer eBooks · doi:10.1007/978-0-387-84851-8_9 · Cited by 5
Differences in the association of inflammation and tryptophan with depressive symptoms between white and non-white chronic dialysis patients.
Haverkamp, G. L. G., Loosman, W. L., Schouten, R. W., Franssen, C., Kema, I., van Diepen, M., Dekker, F., Siegert, C., & Honig, A. (2018) · General Hospital Psychiatry · doi:10.1016/j.genhosppsych.2017.10.003 · Cited by 8
Tryptophan depletion under conditions that imitate insulin resistance enhances fatty acid oxidation and induces endothelial dysfunction through reactive oxygen species-dependent and independent pathways
Eleftheriadis, T., Pissas, G., Sounidaki, M., Antoniadi, G., Rountas, C. D., Liakopoulos, V., & Stefanidis, L. (2017) · Molecular and Cellular Biochemistry · doi:10.1007/s11010-016-2915-7 · Cited by 11
Exposure to Helicobacter pylori and Serum Kynurenine to Tryptophan Ratio in Patients with Gastric Cancer
Engin, A., Karahalil, B., Karakaya, A., & Engin, A. (2010) · Pteridines · doi:10.1515/pteridines.2010.21.1.110 · Cited by 8
Gut microbiome dysregulation in noninfectious uveitis
Liu, M., Geng, J., Liu, T., & Liu, X. (2025) · Frontiers in Immunology · doi:10.3389/fimmu.2025.1614304 · Cited by 7
Sublethal glyphosate exposure reduces honey bee foraging and alters the balance of biogenic amines in the brain
McHenry, L. C., Schürch, R., Gross, A. D., Johnson, L. E., Ohlinger, B. D., & Couvillon, M. J. (2025) · Journal of Experimental Biology · doi:10.1242/jeb.250124 · Cited by 9
Effects of Environmental Pollutants on Tryptophan Metabolism
Hu, H., Lu, X., Wu, M., Bai, Z., & Liu, X. (2025) · Toxics · doi:10.3390/toxics13040311 · Cited by 7
Studies on the alleviating effect of Bifidobacterium lactis V9 on dextran sodium sulfate-induced colitis in mice
Duan, X.-Y., Wu, R., Li, J., Li, Z., Liu, Y.-Q., Chen, P., & Wang, B.-M. (2025) · Frontiers in Medicine · doi:10.3389/fmed.2025.1496023 · Cited by 7
Amino acid profiles, disease activity, and protein intake in adult patients with Crohn’s disease
Cioffi, I., Vincenzo, O. D., Imperatore, N., Fisco, M., Testa, A., Scialò, F., Castiglione, F., Ruoppolo, M., Pasanisi, F., & Santarpia, L. (2023) · Frontiers in Nutrition · doi:10.3389/fnut.2023.1245574 · Cited by 12
“Actually, low Trp levels have been reported in patients with various autoimmune disorders, including IBD (19, 52, 53).”
Background
Incompatible effects of Panax ginseng and Veratrum nigrum on estrogen decline in rats using metabolomics and gut microbiota.
Lin, H., Liu, Z.-Y., Liu, Z.-Q., & Lin, Z. (2021) · Journal of Pharmaceutical and Biomedical Analysis · doi:10.1016/j.jpba.2021.114442 · Cited by 7
Investigating novel biomarkers of immune activation and modulation in the context of sedentary behaviour: a multicentre prospective ischemic stroke cohort study
Alme, K. N., Askim, T., Aßmus, J., Mollnes, T. E., Naik, M., Næss, H., Saltvedt, I. T., Ueland, P. M., Ulvik, A., & Knapskog, A. (2021) · BMC Neurology · doi:10.1186/s12883-021-02343-0 · Cited by 9
“Neopterin and KTR are indirect measures of IFN-ɣ activity, which plays a central role in activating cellular immune response [19, 43].”
Background
Personalized Medicine Using Neuroimmunological Biomarkers in Depressive Disorders
Chi, S., & Lee, M. (2021) · Journal of Personalized Medicine · doi:10.3390/jpm11020114 · Cited by 32
“This enzyme catalyzes the synthesis of kynurenine from tryptophan, a well-known precursor of serotonin, melatonin, and nicotinamide [30].”
Background
Study of the plasmatic levels of tryptophan and kynurenine throughout pregnancy.
Alegre, E., López, A., Díaz-Lagares, Á., & González, Á. (2008) · Clinica chimica acta; international journal of clinical chemistry · doi:10.1016/j.cca.2008.03.011 · Cited by 7
Evaluating the role of kynurenine/tryptophan ratio as an indicator of disease activity in Indian patients with inflammatory bowel disease. A case-control study
Upadhyay, K. G., Desai, D., Ashavaid, T. F., & Dherai, A. J. (2025) · Scandinavian Journal of Gastroenterology · doi:10.1080/00365521.2025.2491784 · Cited by 7
“The K/T ratio was obtained by dividing the plasma concentration of Kyn by the obtained Trp concentration and multiplying the quotient by 1000 [19–23].”
Preoperative Peripheral Blood Serotonin and Kynurenine Levels Are Associated With Oncological Outcomes in Glioblastoma IDH-wt Patients
Snider, S., Gagliardi, F., Domenico, P. D., Comai, S., Bertazzo, A., Nasini, S., Barzon, B., Ruban, A., Roncelli, F., & Mortini, P. (2025) · International Journal of Tryptophan Research · doi:10.1177/11786469241312475 · Cited by 6
The role of tryptophan and its derivatives in musculoskeletal pains: A systematic review and meta‐analysis
Canales, G. D. L. T., Al‐Moraissi, E. A., Fatih, T., Razavian, A., Westman, J. S., Yanes, Y., Grigoriadis, A., Christidis, M., Christidis, N., & Barjandi, G. (2024) · Journal of Oral Rehabilitation · doi:10.1111/joor.13758 · Cited by 5
Laboratory parameters related to disease severity and physical performance after reconvalescence of acute COVID-19 infection
Gietl, M., Burkert, F. R., Hofer, S., Gostner, J. M., Sonnweber, T., Tancevski, I., Pizzini, A., Sahanic, S., Schroll, A., Brigo, N., et al. (2024) · Scientific Reports · doi:10.1038/s41598-024-57448-6 · Cited by 5
Accelerated kynurenine pathway downregulates immune activation in patients with axial spondyloarthritis
Yurt, E. F., Bicer, C. K., Serdar, M. A., Akan, S., & Erten, Ş. (2023) · Cytokine · doi:10.1016/j.cyto.2023.156247 · Cited by 6
Fundamental mechanisms of hexagonal boron nitride sensing of dopamine, tryptophan, ascorbic acid, and uric acid by first-principles study
Rezayei, E., Beheshtian, J., Shayeganfar, F., & Ramazani, A. (2022) · Journal of Molecular Modeling · doi:10.1007/s00894-022-05158-z · Cited by 9
“Trp is a nonpolar aromatic amino acid for the biosynthesis of proteins, which balances nitrogen and maintains the body weight and muscle mass in the human body [20, 21].”
Background

Authors: Schröcksnadel, K., Wirleitner, B., Winkler, C., & Fuchs, D.
Affiliations: Innsbruck Medical University (AT)
Corresponding author: Fuchs, Dietmar
ORCID: Wirleitner, Barbara
Fuchs, Dietmar
Venue: Clinica Chimica Acta
Publisher: Elsevier BV
Published: 2006-02
Volume: 364
Issue: 1-2
Pages: 82-90
ISSN: 0009-8981 (ISSN-L)
DOI: 10.1016/j.cca.2005.06.013
OpenAlex: W2042985653
Cited by: 551
References: 0
Citations by year: 2026: 7 · 2025: 25 · 2024: 19 · 2023: 24 · 2022: 32 · 2021: 47 · 2020: 31 · 2019: 21 · 2018: 27 · 2017: 34 · 2016: 26 · 2015: 32 · 2014: 24 · 2013: 38 · 2012: 36
FWCI: 0.80
Type: journal article
Language: en
Open access: closed
Licence: www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations: Clinica Chimica Acta (publishedVersion)
PubMed (publishedVersion)
Topics: Life Sciences › Neuroscience › Biological Psychiatry › Tryptophan and brain disorders
Life Sciences › Biochemistry, Genetics and Molecular Biology › Biochemistry › Amino Acid Enzymes and Metabolism
Life Sciences › Immunology and Microbiology › Immunology › Reproductive System and Pregnancy
Keywords: tryptophan metabolism, tryptophan depletion, indoleamine 2,3-dioxygenase, tryptophan 2,3-dioxygenase, kynurenine pathway, serotonin synthesis, interferon-gamma, chronic immune activation, Th1 response, neopterin, immunodeficiency, anemia, mood disorders, autoimmune disease, infectious diseases, pregnancy
MeSH terms: Autoimmune Diseases, Humans, Infections, Kynurenine, Neoplasms, Serotonin, Tryptophan, Tryptophan Hydroxylase, Tryptophan Oxygenase, Indoleamine-Pyrrole 2,3,-Dioxygenase

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Monitoring tryptophan metabolism in chronic immune activation

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