Dysbiosis of Gut Microbiota and Activity of KYN Pathway as Potential Biomarkers in Patients With Major Depressive Disorder

With increasing attention on the concept of microbiota-gut-brain axis, increasing evidence has shown that gut microbiota is involved in a variety of neurological and psychiatric diseases. However, the change of gut microbiota in Major Depressive Disorder (MDD) patients and its association with disease mechanism remains to be further elucidated. The present study showed significant changes in ⍺- and β- diversities and relative abundance of gut microbiota in MDD patients, as well as elevation of indoleamine-2,3- dioxygenase (IDO) and kynurenine (KYN) that indicate activation of KYN pathway, which may result in increased neurotoxic metabolites and reduction in generation of serotonin in disease process. These results may potentially be utilized as biomarkers for MDD and play a potential role in the disease mechanisms. Funding Information: This work was supported by the Chinese Medicine Project of Shanghai Municipal Health and Family Planning Commission under Grant 2018LP024; The Characteristic Discipline Construction Project of Shanghai Mental Health Center under Grant 2017-TSXK-07; Shanghai Natural Science fund Project under Grant 20ZR1447700; China Public Health Union(First) Project under Grant GWLM202014; and The hospital-level project of Shanghai Mental Health Center under Grant 2020-YJ05 Declaration of Interests: No potential competing interest was reported by the authors. Ethics Approval Statement: The study was approved by the Institutional Review Board (IRB) at Shanghai Healthy Mental Center, and all participants were provided with written informed consent in line with the Declaration of Helsinki before commencement of the study.