Observational studyBiochimica et biophysica acta. Molecular basis of disease2021
Increased kynurenine-to-tryptophan ratio in the serum of patients infected with SARS-CoV2: An observational cohort study.
Observational study in Biochimica et biophysica acta. Molecular basis of disease, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 60 papers, 2 of them syntheses that pooled it.
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Who cites it
60 citing papers in PubMed, 2 syntheses or guidelines pooled it.
- Metabolomic characteristics and related pathways in patients with different severity of COVID-19: a systematic review and meta-analysis.Journal of global health · 2025Pooled it
- The tryptophan catabolite or kynurenine pathway in COVID-19 and critical COVID-19: a systematic review and meta-analysis.BMC infectious diseases · 2022Pooled it
- Tryptophan-kynurenine metabolic reprogramming along the gut-brain axis alleviates Alzheimer's pathology.Journal of neuroinflammation · 2026Article
- The kynurenine pathway in RNA virus infection: immunometabolic control of antiviral defense and viral persistence.Frontiers in immunology · 2026Review
- The role of immune checkpoint molecules in PRRSV-2-induced immune modulation: insights from comparativeJournal of virology · 2025Article
- Metabolic Reprogramming in Respiratory Viral Infections: A Focus on SARS-CoV-2, Influenza, and Respiratory Syncytial Virus.Biomolecules · 2025Review
- Gut microbiota alterations are linked to COVID-19 severity in North African and European populations.NPJ biofilms and microbiomes · 2025Article
- Immune Response and Serum Biomarker Screening in Pregnant Women with Influenza A Virus Infection: Insight into Susceptibility and Disease Severity.Diseases (Basel, Switzerland) · 2025Article
- Review
- Hydrogen sulfide (H2S) coordinates redox balance, carbon metabolism, and mitochondrial bioenergetics to suppress SARS-CoV-2 infection.PLoS pathogens · 2025Article
- Phenothiazine-linked glutamic acid dendrons: an easy access and a new class of SARS-CoV-2 main protease inhibitors.Royal Society open science · 2025Article
- Severe acute respiratory syndrome coronavirus 2 infection unevenly impacts metabolism in the coronal periphery of the lungs.iScience · 2025Article
- Role of Vitamin D Status and Alterations in Gut Microbiota Metabolism in Fibromyalgia-Associated Chronic Inflammatory Pain.Biomedicines · 2025Article
- Impact of Indoleamine 2,3-Dioxygenase Enzyme Activity in Neuroendocrine Tumors.Neuroendocrinology · 2025Article
- Taurine Supplementation Alleviates Blood Pressure via Gut-Brain Communication in Spontaneously Hypertensive Rats.Biomedicines · 2024Article
- Analysis of the Urine Volatilome of COVID-19 Patients and the Possible Metabolic Alterations Produced by the Disease.Metabolites · 2024Article
- Molecularly Imprinted Ratiometric Fluorescent Sensors for Analysis of Pharmaceuticals and Biomarkers.Sensors (Basel, Switzerland) · 2024Review
- Review
- Review
- Tryptophan catabolism via the kynurenine pathway regulates infection and inflammation: from mechanisms to biomarkers and therapies.Inflammation research : official journal of the European Histamine Research Society ... [et al.] · 2024Review
Corrections and comments
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Authors and funding
23 authors.
Funding
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Abstract
Immune dysregulation is a hallmark of patients infected by SARS-CoV2 and the balance between immune reactivity and tolerance is a key determinant of all stages of infection, including the excessive inflammatory state causing the acute respiratory distress syndrome. The kynurenine pathway (KP) of tryptophan (Trp) metabolism is activated by pro-inflammatory cytokines and drives mechanisms of immune tolerance. We examined the state of activation of the KP by measuring the Kyn:Trp ratio in the serum of healthy subjects (n = 239), and SARS-CoV2-negative (n = 305) and -positive patients (n = 89). Patients were recruited at the Emergency Room of St. Andrea Hospital (Rome, Italy). Kyn and Trp serum levels were assessed by HPLC/MS-MS. Compared to healthy controls, both SARS-CoV2-negative and -positive patients showed an increase in the Kyn:Trp ratio. The increase was larger in SARS-CoV2-positive patients, with a significant difference between SARS-CoV2-positive and -negative patients. In addition, the increase was more prominent in males, and positively correlated with age and severity of SARS-CoV2 infection, categorized as follows: 1 = no need for intensive care unit (ICU); 2 ≤ 3 weeks spent in ICU; 3 ≥ 3 weeks spent in ICU; and 4 = death. The highest Kyn:Trp values were found in SARS-CoV2-positive patients with severe lymphopenia. These findings suggest that the Kyn:Trp ratio reflects the level of inflammation associated with SARS-CoV2 infection, and, therefore, might represent a valuable biomarker for therapeutic intervention.
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