Ciocan, Dragos, Cassard, Anne-Marie, Becquemont, Laurent, Verstuyft, Céline, Voican, Cosmin Sebastian, El Asmar, Khalil, Colle, Romain, David, Denis, Trabado, Séverine, Fève, Bruno, Chanson, Philippe, Perlemuter, Gabriel, Corruble, Emmanuelle, AP-HP - Hôpital Antoine Béclère [Clamart], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), Cytokines, chimiokines et immunopathologie, Université Paris-Sud - Paris 11 (UP11)-Institut National de la Santé et de la Recherche Médicale (INSERM), Inflammation, microbiome, immunosurveillance (MI2), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris-Saclay, Centre de recherche en épidémiologie et santé des populations (CESP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpital Paul Brousse-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris-Saclay, Service de psychiatrie [Le Kremlin-Bicêtre], Université Paris-Sud - Paris 11 (UP11)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpital Bicêtre, Service de Génétique Moléculaire Pharmacogénétique et Hormonologie [CHU Bicêtre], AP-HP Hôpital Bicêtre (Le Kremlin-Bicêtre), Hôpital Bicêtre, Signalisation Hormonale, Physiopathologie Endocrinienne et Métabolique, Université Paris-Sud - Paris 11 (UP11)-Institut National de la Santé et de la Recherche Médicale (INSERM)-AP-HP Hôpital Bicêtre (Le Kremlin-Bicêtre), Centre de Recherche Saint-Antoine (CRSA), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU), Lipodystrophies, adaptations métaboliques et hormonales, et vieillissement [CRSA], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU), CHU Saint-Antoine [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU), Centre de référence des maladies rares de l'hypophyse (HYPO), Service d'Endocrinologie, Diabète et Maladies Métaboliques, and Feve, Bruno
International audience; Background: The microbiota interacts with the brain through the gut-brain axis, and a distinct dysbiosis may lead to major depressive episodes. Bacteria can pass through the gut barrier and be found in the blood. Using a multiomic approach, we investigated whether a distinct blood microbiome and metabolome was associated with major depressive episodes, and how it was modulated by treatment.Methods: In this case-control multiomic study, we analyzed the blood microbiome composition, inferred bacterial functions and metabolomic profile of 56 patients experiencing a current major depressive episode and 56 matched healthy controls, before and after treatment, using 16S rDNA sequencing and liquid chromatography coupled to tandem mass spectrometry.Results: The baseline blood microbiome in patients with a major depressive episode was distinct from that of healthy controls (patients with a major depressive episode had a higher proportion of Janthinobacterium and lower levels of Neisseria) and changed after antidepressant treatment. Predicted microbiome functions confirmed by metabolomic profiling showed that patients who were experiencing a major depressive episode had alterations in the cyanoamino acid pathway at baseline. High baseline levels of Firmicutes and low proportions of Bosea and Tetrasphaera were associated with response to antidepressant treatment. Based on inferred baseline metagenomic profiles, bacterial pathways that were significantly associated with treatment response were related to xenobiotics, amino acids, and lipid and carbohydrate metabolism, including tryptophan and drug metabolism. Metabolomic analyses showed that plasma tryptophan levels are independently associated with response to antidepressant treatment.Limitations: Our study has some limitations, including a lack of information on blood microbiome origin and the lack of a validation cohort to confirm our results.Conclusion: Patients with depression have a distinct blood microbiome and metabolomic signature that changes after treatment. Dysbiosis could be a new therapeutic target and prognostic tool for the treatment of patients who are experiencing a major depressive episode.