ReviewClinical science (London, England : 1979)2016
The end of the road for the tryptophan depletion concept in pregnancy and infection.
Review in Clinical science (London, England : 1979), 2016. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 49 papers.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
49 citing papers in PubMed, 88 citations in OpenAlex.
- Tryptophan's Journey Through Pregnancy: The Role of Serotonin.International journal of tryptophan research : IJTR · 2026Review
- Indoleamine 2,3-Dioxygenase Regulates Placental Trophoblast Cell Invasion.International journal of molecular sciences · 2025Article
- The Kynurenine Pathway and Indole Pathway in Tryptophan Metabolism Influence Tumor Progression.Cancer medicine · 2025Review
- Excessive progesterone impairs mouse decidualization via the Kyn-AhR pathway.Frontiers in cell and developmental biology · 2025Article
- Metabolomic Profiling Reveals Serum Tryptophan as a Potential Therapeutic Target for Systemic Lupus Erythematosus.Journal of inflammation research · 2025Article
- Molecular mechanisms and therapeutic significance of Tryptophan Metabolism and signaling in cancer.Molecular cancer · 2024Review
- Bridging the divide: unveiling mutual immunological pathways of cancer and pregnancy.Inflammation research : official journal of the European Histamine Research Society ... [et al.] · 2024Review
- Tryptophan in the mouse diet is essential for embryo implantation and decidualization.Frontiers in endocrinology · 2024Article
- Maternal Tryptophan Catabolites and Insulin Resistance Parameters in Preeclampsia.Biomolecules · 2023Article
- The kynurenine pathway of tryptophan metabolism: a neglected therapeutic target of COVID-19 pathophysiology and immunotherapy.Bioscience reports · 2023Article
- IDO1 and inflammatory neovascularization: bringing new blood to tumor-promoting inflammation.Frontiers in oncology · 2023Review
- Tryptophan metabolism and disposition in cancer biology and immunotherapy.Bioscience reports · 2022Article
- Analysis of Tryptophan and Its Main Metabolite Kynurenine and the Risk of Multiple Cancers Based on the Bidirectional Mendelian Randomization Analysis.Frontiers in oncology · 2022Article
- Alterations in the vaginal microbiota of patients with preterm premature rupture of membranes.Frontiers in cellular and infection microbiology · 2022Article
- Reliable chromatographic assay for measuring of indoleamine 2,3-dioxygenase 1 (IDO1) activity in human cancer cells.Journal of enzyme inhibition and medicinal chemistry · 2021Article
- The Function of the Kynurenine Pathway in the Placenta: A Novel Pharmacotherapeutic Target?International journal of environmental research and public health · 2021Review
- Electrochemical Determination of Kynurenine Pathway Metabolites-Challenges and Perspectives.Sensors (Basel, Switzerland) · 2021Review
- Tryptophan Metabolism via Kynurenine Pathway: Role in Solid Organ Transplantation.International journal of molecular sciences · 2021Review
- Emerging Roles on Immunological Effect of Indoleamine 2,3-Dioxygenase in Liver Injuries.Frontiers in medicine · 2021Review
- Inhibition of 2-Oxoglutarate Dehydrogenase as a Chemical Model of Acute Hypobaric Hypoxia.Frontiers in medicine · 2021Article
Corrections and comments
- Commented on by
Authors and funding
3 authors at 2 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
We hypothesize that: (1) L-tryptophan (Trp) is greatly utilized and not depleted in pregnancy; (2) fetal tolerance is achieved in part through immunosuppressive kynurenine (Kyn) metabolites produced by the flux of plasma free (non-albumin-bound) Trp down the Kyn pathway; (3) the role of indoleamine 2,3-dioxygenase (IDO) in infection is not related to limitation of an essential amino acid, but is rather associated with stress responses and the production of Kyn metabolites that regulate the activities of antigen presenting cells and T-cells, as well as increased NAD(+) synthesis in IDO-expressing cells; (4) Trp depletion is not a host defence mechanism, but is a consequence of Trp utilization. We recommend that future studies in normal and abnormal pregnancies and in patients with infections or cancer should include measurements of plasma free Trp, determinants of Trp binding (albumin and non-esterified fatty acids), total Trp, determinants of activities of the Trp-degrading enzymes Trp 2,3-dioxygenase (TDO) (cortisol) and IDO (cytokines) and levels of Kyn metabolites. We also hypothesize that abnormal pregnancies and failure to combat infections or cancer may be associated with excessive Trp metabolism that can lead to pathological immunosuppression by excessive production of Kyn metabolites. Mounting evidence from many laboratories indicates that Trp metabolites are key regulators of immune cell behaviour, whereas Trp depletion is an indicator of extensive utilization of this key amino acid.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.