The Immunomodulator 1-Methyltryptophan Drives Tryptophan Catabolism Toward the Kynurenic Acid Branch
Overview
Affiliations
Animal model studies revealed that the application of 1-methyltryptophan (1-MT), a tryptophan (TRP) analog, surprisingly increased plasma levels of the TRP metabolite, kynurenic acid (KYNA). Under inflammatory conditions, KYNA has been shown to mediate various immunomodulatory effects. Therefore, the present study aims to confirm and clarify the effects of 1-MT on TRP metabolism in mice as well as in humans. Splenocytes from Balb/C or indoleamine 2,3-dioxygenase knockout () mice or whole human blood were stimulated with 1-MT for 6, 24, or 36 h. C57BL/6 mice received 1-MT in drinking water for 5 days. Cell-free supernatants and plasma were analyzed for TRP and its metabolites by tandem mass spectrometry (MS/MS). 1-MT treatment induced an increase in TRP and its metabolite, KYNA in Balb/C, mice, and in human blood. Concurrently, the intermediate metabolite kynurenine (KYN), as well as the KYN/TRP ratio, were reduced after 1-MT treatment. The effects of 1-MT on TRP metabolites were similar after the application of 1-MT to C57BL/6 mice. The data indicate that 1-MT induced an increase of KYNA and confirming previously described results. Furthermore, the results of mice indicate that this effect seems not to be mediated by IDO1. Due to the proven immunomodulatory properties of KYNA, a shift toward this branch of the kynurenine pathway (KP) may be one potential mode of action by 1-MT and should be considered for further applications.
Ali NejadKasbakhi N, Vavrincova D, cepcova D Arch Razi Inst. 2024; 79(2):307-314.
PMID: 39463718 PMC: 11512173. DOI: 10.32592/ARI.2024.79.2.307.
Chen X, Xu D, Yu J, Song X, Li X, Cui Y Nutrients. 2024; 16(19).
PMID: 39408347 PMC: 11478743. DOI: 10.3390/nu16193380.
Kynurenines as a Novel Target for the Treatment of Inflammatory Disorders.
Mor A, Tankiewicz-Kwedlo A, Ciwun M, Lewkowicz J, Pawlak D Cells. 2024; 13(15.
PMID: 39120289 PMC: 11311768. DOI: 10.3390/cells13151259.
knock-out parasites reprogram tryptophan metabolism to induce a pro-inflammatory response.
Oljuskin T, Azodi N, Volpedo G, Bhattacharya P, Markle H, Hamano S iScience. 2023; 26(9):107593.
PMID: 37744403 PMC: 10517402. DOI: 10.1016/j.isci.2023.107593.
Inflammation in the pathogenesis of depression: a disorder of neuroimmune origin.
Corrigan M, ORourke A, Moran B, Fletcher J, Harkin A Neuronal Signal. 2023; 7(2):NS20220054.
PMID: 37457896 PMC: 10345431. DOI: 10.1042/NS20220054.