• Abbas F Almulla, Yanin Thipakorn, Bo Zhou, Aristo Vojdani, Rossitsa Paunova, and Michael Maes.
• Sichuan Provincial Center for Mental Health, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China; Key Laboratory of Psychosomatic Medicine, Chinese Academy of Medical Sciences, Chengdu 610072, China; Department of Psychiatry, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Medical Laboratory Technology Department, College of Medical Technology, The Islamic University, Najaf, Iraq.
• Neuroscience. 2024 Dec 17; 563: 268277268-277.

BackgroundRecent studies confirm the involvement of activated immune-inflammatory responses and increased oxidative and nitrosative stress in Long COVID (LC) disease. However, the influence of these pathways on the metabolism of tryptophan (TRP) through the TRP catabolite (TRYCAT) pathway and their mediating effects on LC pathophysiology, has not been fully explored.ObjectiveThis meta-analysis investigates peripheral TRP and TRYCAT levels and the TRYCAT pathway in patients with LC disease.MethodThis review utilized systematic searches of PubMed, Google Scholar, SCOPUS and SciFinder, including 14 full-text articles and 1,167 participants, consisting of 480 patients with LC and 687 normal controls.ResultsThe results indicated a significant increase in the kynurenine (KYN)/TRP ratio, with a large effect size (standardized mean difference, SMD = 0.755; confidence intervals, CI: 0.119;1.392), in LC patients compared to normal controls. Additionally, LC patients exhibited a significant decrease in TRP levels (SMD = -0.520, CI: -0.793; -0.246) and an increase in KYN levels after imputing missing studies (SMD = 1.176, CI: 0.474; 1.877), suggesting activation of the indoleamine 2,3-dioxygenase (IDO) enzyme and upregulation of the TRYCAT pathway. No significant elevation in TRYCAT-related neurotoxicity, kynurenic acid (KA)/KYN and 3-hydroxykynurenine (3-HK)/KYN ratios were observed in LC patients compared to normal controls.ConclusionThe current findings suggest that an activated TRYCAT pathway, characterized by decreased TRP levels and maybe elevated KYN levels, plays a significant role in the pathophysiology of LC.Copyright © 2024 International Brain Research Organization (IBRO). Published by Elsevier Inc. All rights reserved.

14 keywords...

hide…