Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2024 Jan 10;25(2):853. doi: 10.3390/ijms25020853

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© 2024 by the authors.

Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

PMC Copyright notice

Pro-inflammatory cytokines, including TNF-α, IFN-γ, and IL-6, activate IDO, which in consequence activates TDO, converting Tryptophan to Kynurenine. The conversion of accessible Tryptophan into Kynurenine increases proportionately with increased IDO activation. Pro-inflammatory cytokines also stimulate the activity of the microglia’s QA transformation chain enzymes. Increased activity from Kynureninase (KYNU), kynurenine 3-monooxygenase (KMO), and 3-hydroxyanthranilic acid oxygenase (3-HAO) encourages a higher conversion of Kynurenine into its final product, QA. This neurotoxic metabolite can enhance oxidative stress by favorably influencing the generation of ROS. Neuroinflammation and oxidative stress result in neurodegeneration.