Gut microbial modulation of 3-hydroxyanthranilic acid and dopaminergic signalling influences attention in obesity

Abstract

Background Obesity-related alterations in the gut microbiota have been linked to cognitive decline, yet their relationship with attention remains poorly understood. Objective To evaluate the possible relationships among gut metagenomics, plasma metabolomics and attention. Design We conducted faecal shotgun metagenomics and targeted plasma tryptophan metabolomics across three independent cohorts (n=156, n=124, n=804) with functional validations in preclinical models, including three faecal microbiota transplantation (FMT) experiments in mice and Drosophila melanogaster. Results Obesity was consistently associated with reduced attention. Metagenomics analyses identified Proteobacteria species and microbial functions related to tryptophan biosynthesis from anthranilic acid (AA) as negatively associated with attention in obesity. Plasma tryptophan metabolic profiling and machine learning revealed that 3-hydroxyanthranilic acid (3-HAA) was positively associated with attention, particularly in obesity, while AA showed a negative association. Bariatric surgery improved attention and enriched microbial species linked to attention. In mice, diet-induced obesity (DIO) and microbiota depletion reduced 3-HAA and 5-hydroxy-indole acetic acid (5-HIAA) concentrations in the prefrontal cortex (PFC), which were restored by FMT. Global metabolic profiling (>600 metabolites) of PFC from the FMT group identified 3-HAA and the tryptophan and tyrosine pathways among the most significant in mice receiving microbiota from high-attention donors. A second FMT experiment also revealed a consistent enrichment of the tryptophan and tyrosine metabolism at the transcriptional level in the PFC, with Haao (3-hydroxyantrhanilic acid dioxygenase) and Aox4 (aldehyde oxidase 4), key in 3-HAA and 5-HIAA degradation, among the significantly regulated genes. In a third FMT study, attentional traits were transmitted from humans to mice alongside modulation of serotonergic and dopaminergic pathways. In Drosophila, mono-colonisation with Enterobacter cloacae and DIO induced attention deficit-like behaviours, which were mitigated by 3-HAA supplementation. Conclusions We have identified the microbiota and 3-HAA as potential therapeutic targets to improve attention, especially in obesity.

This work was partially supported by Instituto de Salud Carlos III through the projects PI20/01090 and PI23/00575 (co-funded by the European Union under the European Regional Development Fund. "A way to make Europe") to JM-P and PI21/01361 and PI24/00185 and ICREA-Acadèmia (#2021) to JMF-R, the project CNS2023-144218 funded by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR to JM-P, and Generalitat de Catalunya 2021 SGR 01263. This work has also been co-financed by the Spanish Ministry of Science, Innovation and Universities with funds from the European Union NextGenerationEU, from the Recovery, Transformation and Resilience Plan (PRTR-C17.I1) and from the Autonomous Community of Catalonia within the framework of the Biotechnology Plan Applied to Health through the project PPCCADGUT to JM-P. AF is funded by the Horizon 2020 Framework Programme of the European Union under the Marie Sklodowska-Curie Innovative Training Network grant agreement No 859890. MA-R is funded by Instituto de Salud Carlos III (Madrid, Spain) through a predoctoral Río Hortega contract CM19/00190 (co-funded by European Regional Development Fund "Investing in your future"). AC-N is funded by Instituto de Salud Carlos III (Madrid, Spain) through the Miguel Servet Program CP24/00033 (co-funded by European Regional Development Fund "Investing in your future"). IDIBGI is a CERCA centre from the "CERCA Programme/Generalitat de Catalunya". This study was conducted using samples/data from the Healthy Imageomics Study, supported by the Specialization and Territorial Competitiveness Projects (PECT) within the RIS3Cat and the Catalonia ERDF Operational Programme 2014-2020. It was co-financed by the European Regional Development Fund (ERDF) of the European Union under the Catalonia ERDF Operational Programme 2014-2020 and by the Diputació de Girona. We want to particularly acknowledge the participants, to the IDIBGI Horizontal Aging Program and the IDIBGI Biobank (Biobanc IDIBGI, B.0000872), integrated in the Platform ISCIII Biomodels and Biobanks, for their collaboration. This work was also supported by Ministerio de Ciencia, Innovación y Universidades, Agencia Estatal de Investigación (AEI) (PID2020- 120029GB-I00/MICIN/AEI/ 10.13039/501100011033, RD21/0009/0019 and PDI20231511680B-C21), the Spanish "Instituto de Salud Carlos III, RETICSRTA" (#RD12/0028/0023), the "Generalitat de Catalunya, AGAUR" (#2017 SGR-669), "ICREA-Acadèmia" (#2015) and the Spanish "Ministerio de Sanidad, Servicios Sociales e Igualdad", "Plan Nacional Sobre Drogas of the Spanish Ministry of Health" (#PNSD-2017I068) to RM, la Caixa Health" LCR/PR/HR22/5240017 to RM and EM-G, "Plan Nacional Sobre Drogas of the Spanish Ministry of Health" (#PNSD2019I006, #PNSD-2023I040) and Spanish "Ministerio de Ciencia e Innovación" (ERA-NET) PCI2021-122073-2A to EM-G.