Microbiota alterations in proline metabolism impact depression

Aminoàcids; Depressió; MicrobiotaAminoácidos; Depresión; MicrobiotaAmino acids; Depression; MicrobiotaThe microbiota-gut-brain axis has emerged as a novel target in depression, a disorder with low treatment efficacy. However, the field is dominated by underpowered studies focusing on major depression not addressing microbiome functionality, compositional nature, or confounding factors. We applied a multi-omics approach combining pre-clinical models with three human cohorts including patients with mild depression. Microbial functions and metabolites converging onto glutamate/GABA metabolism, particularly proline, were linked to depression. High proline consumption was the dietary factor with the strongest impact on depression. Whole-brain dynamics revealed rich club network disruptions associated with depression and circulating proline. Proline supplementation in mice exacerbated depression along with microbial translocation. Human microbiota transplantation induced an emotionally impaired phenotype in mice and alterations in GABA-, proline-, and extracellular matrix-related prefrontal cortex genes. RNAi-mediated knockdown of proline and GABA transporters in Drosophila and mono-association with L. plantarum, a high GABA producer, conferred protection against depression-like states. Targeting the microbiome and dietary proline may open new windows for efficient depression treatment.This work was partially supported by Instituto de Salud Carlos III (Madrid, Spain) through the research grants PI15/01934, PI18/01022, and PI21/01361 to J.M.F.-R. and PI20/01090 (co-funded by the European Regional Development Fund. “A way to make Europe”) to J.M.-P.; the Catalan Government (AGAUR, #SGR2017-0734, ICREA Academia Award 2021) to J.M.F.-R.; the Spanish Ministry of Science, Innovation and Universities (PID2019-105969GB-I00); Generalitat Valenciana (Prometeo/2018/133), Spain; and Fondo Europeo de Desarrollo Regional (FEDER) funds to A.M. This work was also supported by the European Commission (FP7, NeuroPain #2013-602891); the Catalan Government (AGAUR, #SGR2017-669, ICREA Academia Award 2020) to R.M.; the Spanish Instituto de Salud Carlos III (RTA, #RD16/0017/0020) to R.M.; Ministry of Science and Innovation and State Research Agency (#PID2020- 120029GB-I00/MICIN/AEI/10.13039/501100011033) to R.M.; the European Regional Development Fund (project no. 01.2.2-LMT-K-718-02-0014) under grant agreement with the Research Council of Lithuania (LMTLT); and the Project ThinkGut (EFA345/19), 65% co-financed by the European Regional Development Fund (ERDF) through the Interreg V-A Spain-France-Andorra program (POCTEFA, 2014–2020). We also acknowledge funding from the Spanish Ministry of Science, Innovation and Universities (RTI2018-099200-B-I00) and the Generalitat of Catalonia (Agency for Management of University and Research Grants [2017SGR696] and Department of Health [SLT002/16/00250]) to R.P. M.A.-R. is funded by Instituto de Salud Carlos III, Río Hortega (CM19/00190). J.M.-P. is funded by a Miguel Servet contract (CP18/00009) from the Instituto de Salud Carlos III. J.S. is funded by a predoctoral PERIS contract (SLT002/16/00250) from the Catalan Government. M.J. is a professor under “Serra Hunter” program (Generalitat de Catalunya)

Obesity status and obesity-associated gut dysbiosis effects on hypothalamic structural covariance

Background: Functional connectivity alterations in the lateral and medial hypothalamic networks have been associated with the development and maintenance of obesity, but the possible impact on the structural properties of these networks remains largely unexplored. Also, obesity-related gut dysbiosis may delineate specific hypothalamic alterations within obese conditions. We aim to assess the effects of obesity, and obesity and gut-dysbiosis on the structural covariance differences in hypothalamic networks, executive functioning, and depressive symptoms. Methods: Medial (MH) and lateral (LH) hypothalamic structural covariance alterations were identified in 57 subjects with obesity compared to 47 subjects without obesity. Gut dysbiosis in the subjects with obesity was defined by the presence of high (n = 28) and low (n = 29) values in a BMI-associated microbial signature, and posthoc comparisons between these groups were used as a proxy to explore the role of obesity-related gut dysbiosis on the hypothalamic measurements, executive function, and depressive symptoms. Results: Structural covariance alterations between the MH and the striatum, lateral prefrontal, cingulate, insula, and temporal cortices are congruent with previously functional connectivity disruptions in obesity conditions. MH structural covariance decreases encompassed postcentral parietal cortices in the subjects with obesity and gut-dysbiosis, but increases with subcortical nuclei involved in the coding food-related hedonic information in the subjects with obesity without gut-dysbiosis. Alterations for the structural covariance of the LH in the subjects with obesity and gut-dysbiosis encompassed increases with frontolimbic networks, but decreases with the lateral orbitofrontal cortex in the subjects with obesity without gut-dysbiosis. Subjects with obesity and gut dysbiosis showed higher executive dysfunction and depressive symptoms. Conclusions: Obesity-related gut dysbiosis is linked to specific structural covariance alterations in hypothalamic networks relevant to the integration of somatic-visceral information, and emotion regulation

Serum Neuregulin 4 is negatively correlated with insulin sensitivity in humans and impairs mitochondrial respiration in HepG2 cells

Neuregulin 4 (NRG4) has been described to improve metabolic disturbances linked to obesity status in rodent models. The findings in humans are controversial. We aimed to investigate circulating NRG4 in association with insulin action in humans and the possible mechanisms involved. Insulin sensitivity (euglycemic hyperinsulinemic clamp) and serum NRG4 concentration (ELISA) were analysed in subjects with a wide range of adiposity (n = 89). In vitro experiments with human HepG2 cell line were also performed. Serum NRG4 was negatively correlated with insulin sensitivity (r = −0.25, p = 0.02) and positively with the inflammatory marker high-sensitivity C reative protein (hsCRP). In fact, multivariant linear regression analyses showed that insulin sensitivity contributed to BMI-, age-, sex-, and hsCRP-adjusted 7.2% of the variance in serum NRG4 (p = 0.01). No significant associations were found with adiposity measures (BMI, waist circumference or fat mass), plasma lipids (HDL-, LDL-cholesterol, or fasting triglycerides) or markers of liver injury. Cultured hepatocyte HepG2 treatedwith human recombinantNRG4 had an impact on hepatocyte metabolism, leading to decreased gluconeogenic- and mitochondrial biogenesis-related gene expression, and reduced mitochondrial respiration, without effects on expression of lipid metabolism-related genes. Similar but more pronounced effects were found after neuregulin 1 administration. In conclusion, sustained higher serum levels of neuregulin-4, observed in insulin resistant patients may have deleterious effects on metabolic and mitochondrial function in hepatocytes. However, findings from in vitro experiments should be confirmed in human primary hepatocytes

Presence of Blastocystis in the gut microbiota is associated with cognitive traits and decreased executive function

Growing evidence implicates the gut microbiome in cognition. Blastocystis is a common gut single-cell eukaryote parasite frequently detected in humans but its potential involvement in human pathophysiology has been poorly characterized. Here we describe how the presence of Blastocystis in the gut microbiome was associated with deficits in executive function and altered gut bacterial composition in a discovery (n = 114) and replication cohorts (n = 942). We also found that Blastocystis was linked to bacterial functions related to aromatic amino acids metabolism and folate-mediated pyrimidine and one-carbon metabolism. Blastocystis-associated shifts in bacterial functionality translated into the circulating metabolome. Finally, we evaluated the effects of microbiota transplantation. Donor's Blastocystis subtypes led to altered recipient's mice cognitive function and prefrontal cortex gene expression. In summary, Blastocystis warrant further consideration as a novel actor in the gut microbiome-brain axis

Subjects with detectable Saccharomyces cerevisiae in the gut microbiota show deficits in attention and executive function

This work was partially supported by research grants FIS (PI15/01934 and PI18/01022) from the Instituto de Salud Carlos III from Spain, SAF2015-65878-R and RTI2018-099200-B-I00 from the Ministerio de Economía y Competitividad, Prometeo/2018/A/133 from Generalitat Valenciana, Spain, and also by Fondo Europeo de Desarrollo Regional (FEDER) funds, European Commission (FP7, NeuroPain #2013-602891), the Generalitat of Catalunya (AGAUR, #SGR2017-669, #SGR2017-696, Department of Health SLT002/16/00250; ICREA Academia Award 2015), the Instituto de Salud Carlos III from Spain (RTA, #RD16/0017/0020) and the Fondo Europeo de Desarrollo Regional (No. 01.2.2-LMT-K-718-02-0014); and by Project ThinkGut (EFA345/19), 65% co-financed by the European Regional Development Fund (ERDF) through the Interreg V-A Spain-France-Andorra programme (POCTEFA 2014-2020). María Arnoriaga-Rodríguez is funded by Instituto de Salud Calos III, Río Hortega (CP19/00190). Jordi Mayneris-Perxachs is funded by the Miguel Servet Program from the Instituto de Salud Carlos III (ISCIII CP18/00009), co-funded by the European Social Fund “Investing in your future”. Mariona Jové is a professor under the Serra Hunter programme (Generalitat de Catalunya).Peer reviewe

DPP9 as a Potential Novel Mediator in Gastrointestinal Virus Infection

Dipeptidyl peptidase 9 (DPP9) is a member of the dipeptidyl peptidase IV family. Inhibition of DPP9 has recently been shown to activate the nucleotide-binding domain leucine-rich repeat 1 (NLRP1) inflammasome. NLRP1 is known to bind nucleic acids with high affinity and directly interact with double stranded RNA, which plays a key role in viral replication. DPP9 has also recently emerged as a key gene related to lung-inflammation in critical SARS-CoV-2 infection. Importantly, DPP9 activity is strongly dependent on the oxidative status. Here, we explored the potential role of DPP9 in the gastrointestinal tract. We performed transcriptomics analyses of colon (microarray, n = 37) and jejunal (RNA sequencing, n = 31) biopsies from two independent cohorts as well as plasma metabolomics analyses in two independent cohorts (n = 37 and n = 795). The expression of DPP9 in the jejunum, colon, and blood was significantly associated with circulating biomarkers of oxidative stress (uric acid, bilirubin). It was also associated positively with the expression of transcription factors (NRF-2) and genes (SOD, CAT, GPX) encoding for antioxidant enzymes, but negatively with that of genes (XDH, NOX) and transcription factors (NF-KB) involved in ROS-generating enzymes. Gene co-expression patterns associated with DPP9 identified several genes participating in antiviral pathways in both tissues. Notably, DPP9 expression in the colon and plasma was strongly positively associated with several circulating nucleotide catabolites (hypoxanthine, uric acid, 3-ureidopropionic acid) with important roles in the generation of ROS and viral infection, as well as other metabolites related to oxidative stress (Resolvin D1, glutamate-containing dipeptides). Gene-drug enrichment analyses identified artenimol, puromycin, anisomycin, 3-phenyllactic acid, and linezolid as the most promising drugs targeting these DPP9-associated genes. We have identified a novel potential pathogenic mechanism of viral infection in the digestive tract and promising existing drugs that can be repositioned against viral infection.This work was partially supported by Fundació Marató de TV3 research grant number 201612-31 and by Instituto de Salud Carlos III (ISCIII, Madrid, Spain) through the project PI20/01090 (co-funded by the European Union under the European Regional Development Fund (FEDER). “A way to make Europe”) to J.M.-P. Á.d.C.-I. is funded by Girona Biomedical Research Institute (Girona, Spain) through the Horizon 2020 Framework Programme of the European Union under the Marie Skłodowska-Curie Innovative Training Network grant agreement No 859890. M.A.-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”). J.M.-P. is funded by Instituto de Salud Carlos III (Madrid, Spain) through the Miguel Servet Program CP18/00009 (co-funded by European Regional Development Fund “Investing in your future”)

Activation of Endogenous H2S Biosynthesis or Supplementation with Exogenous H2S Enhances Adipose Tissue Adipogenesis and Preserves Adipocyte Physiology in Humans

Aims: To investigate the impact of exogenous hydrogen sulfide (H2S) and its endogenous biosynthesis on human adipocytes and adipose tissue in the context of obesity and insulin resistance. Results: Experiments in human adipose tissue explants and in isolated preadipocytes demonstrated that exogenous H2S or the activation of endogenous H2S biosynthesis resulted in increased adipogenesis, insulin action, sirtuin deacetylase, and PPARγ transcriptional activity, whereas chemical inhibition and gene knockdown of each enzyme generating H2S (CTH, CBS, MPST) led to altered adipocyte differentiation, cellular senescence, and increased inflammation. In agreement with these experimental data, visceral and subcutaneous adipose tissue expression of H2S-synthesising enzymes was significantly reduced in morbidly obese subjects in association with attenuated adipogenesis and increased markers of adipose tissue inflammation and senescence. Interestingly, weight-loss interventions (including bariatric surgery or diet/exercise) improved the expression of H2S biosynthesis-related genes. In human preadipocytes, the expression of CTH, CBS, and MPST genes and H2S production were dramatically increased during adipocyte differentiation. More importantly, the adipocyte proteome exhibiting persulfidation was characterized, disclosing that different proteins involved in fatty acid and lipid metabolism, the citrate cycle, insulin signaling, several adipokines, and PPAR, experienced the most dramatic persulfidation (85–98%). Innovation: No previous studies investigated the impact of H2S on human adipose tissue. This study suggests that the potentiation of adipose tissue H2S biosynthesis is a possible therapeutic approach to improve adipose tissue dysfunction in patients with obesity and insulin resistance. Conclusion: Altogether, these data supported the relevance of H2S biosynthesis in the modulation of human adipocyte physiology.Peer reviewe

Obesity status and obesity-associated gut dysbiosis effects on hypothalamic structural covariance

[Background]: Functional connectivity alterations in the lateral and medial hypothalamic networks have been associated with the development and maintenance of obesity, but the possible impact on the structural properties of these networks remains largely unexplored. Also, obesity-related gut dysbiosis may delineate specific hypothalamic alterations within obese conditions. We aim to assess the effects of obesity, and obesity and gut-dysbiosis on the structural covariance differences in hypothalamic networks, executive functioning, and depressive symptoms.[Methods]: Medial (MH) and lateral (LH) hypothalamic structural covariance alterations were identified in 57 subjects with obesity compared to 47 subjects without obesity. Gut dysbiosis in the subjects with obesity was defined by the presence of high (n = 28) and low (n = 29) values in a BMI-associated microbial signature, and posthoc comparisons between these groups were used as a proxy to explore the role of obesity-related gut dysbiosis on the hypothalamic measurements, executive function, and depressive symptoms.[Results]: Structural covariance alterations between the MH and the striatum, lateral prefrontal, cingulate, insula, and temporal cortices are congruent with previously functional connectivity disruptions in obesity conditions. MH structural covariance decreases encompassed postcentral parietal cortices in the subjects with obesity and gut-dysbiosis, but increases with subcortical nuclei involved in the coding food-related hedonic information in the subjects with obesity without gut-dysbiosis. Alterations for the structural covariance of the LH in the subjects with obesity and gut-dysbiosis encompassed increases with frontolimbic networks, but decreases with the lateral orbitofrontal cortex in the subjects with obesity without gut-dysbiosis. Subjects with obesity and gut dysbiosis showed higher executive dysfunction and depressive symptoms.[Conclusions]: Obesity-related gut dysbiosis is linked to specific structural covariance alterations in hypothalamic networks relevant to the integration of somatic-visceral information, and emotion regulation.This study has been funded by the Project Grant IRONMET (PI15/01934) from the ISCIII, and the Project ThinkGut (EFA345/19) 65% co-financed by the European Regional Development Fund (ERDF) through the Interreg V-A Spain-France-Andorra program (POCTEFA 2014–2020) (JM Fernández-Real). Partial support was also obtained by the Ministerio de Economia y Competitividad, Spain, reference MTM2015-64465-C2-1-R (ML Calle). O Contreras-Rodriguez is funded by a “PERIS” postdoctoral fellowship (SLT006/17/00236) from the Health Department of the Catalan Government and by a “Miguel Servet” contract (CP20/00165) from the ISCIII. M Arnoriaga-Rodríguez is funded by a predoctoral Rio Hortega contract (CM19/00190) co-funded by European Social Fund “Investigating in your future” from the ISCIII.Peer reviewe

Microbiota alterations in proline metabolism impact depression

The microbiota-gut-brain axis has emerged as a novel target in depression, a disorder with low treatment efficacy. However, the field is dominated by underpowered studies focusing on major depression not ad- dressing microbiome functionality, compositional nature, or confounding factors. We applied a multi-omics approach combining pre-clinical models with three human cohorts including patients with mild depression. Microbial functions and metabolites converging onto glutamate/GABA metabolism, particularly proline, were linked to depression. High proline consumption was the dietary factor with the strongest impact on depression. Whole-brain dynamics revealed rich club network disruptions associated with depression and circulating proline. Proline supplementation in mice exacerbated depression along with microbial translocation. Human microbiota transplantation induced an emotionally impaired phenotype in mice and alterations in GABA-, proline-, and extracellular matrix-related prefrontal cortex genes. RNAi-mediated knockdown of pro-line and GABA transporters in Drosophila and mono-association with L. plantarum, a high GABA producer, conferred protection against depression-like states. Targeting the microbiome and dietary proline may open new windows for efficient depression treatment

Cognitive function in obesity: interactions with the gut microbiome

Obesity is considered a modifiable risk factor for cognitive impairment which, in turn, predisposes to overeating and weight gain. Compelling evidence in animal models has demonstrated the impact of the gut microbiome on cognition, in general, and cognitive decline in obesity, in particular. However, in humans, while the role of the gut microbiome in obesity pathophysiology is acknowledged, the effects on obesity-associated cognitive dysfunction are limited. The present thesis aims to describe the impact of the gut microbiome on cognitive function in middle-aged subjects with obesity. For this purpose, a prospective longitudinal case-control study (n=114) of subjects with and without obesity was conducted. Clinical evaluation, neurocognitive assessment of memory and inhibitory control, brain gray matter volume through magnetic resonance imaging, fecal metagenomics and fecal/plasma metabolomics were performed. Some parameters were also measured in two independent cohorts (n=24, n=970). The experimental design included fecal microbiota transplantation models from humans to mice and afterwards neuropsychological testing and prefrontal cortex gene expression analysis in the recipient mice. The results point to the existence of an ecosystem of gut bacteria that is differentially linked to memory function and inhibitory control in subjects with and without obesity. In this sense, impairments in memory and inhibitory control were observed in individuals with obesity. Convergent and divergent patterns of bacterial species, functions and circulating metabolites were longitudinally described and mostly replicated in independent cohorts. In particular, alterations in aromatic amino acids and one-carbon metabolism pathways were identified. Gray matter volume of brain areas involved in memory and inhibitory control were concordantly associated with the gut microbiome profile. Finally, cognitive deficits from human donors with obesity were phenocopied in recipient mice through fecal microbiota transplantation, leading to decreased memory and inhibition-like behavior scores in mice and congruent associations with human donor’s metagenomic species and functions. Mice prefrontal cortex expression of aromatic amino acids- and one-carbon metabolism-related genes were simultaneously linked to the cognition-like behaviors in mice and different human bacterial clusters. Overall, these innovative findings suggest bidirectional host-microbiome networks that may impact brain physiology and highlight the potential diagnostic and therapeutic value of targeting the gut microbiome for the impairment of memory and inhibitory control, particularly in subjects with obesityL'obesitat es considera un factor de risc modificable per al deteriorament cognitiu que, al seu torn, predisposa a menjar en excés i augmentar de pes. S’han trobat evidències convincents en models animals que han demostrat l'impacte del microbioma intestinal en la cognició, en general, i el declivi cognitiu de l'obesitat, en particular. Tanmateix, en humans, tot i que es reconeix el paper del microbioma intestinal en la fisiopatologia de l'obesitat, els efectes sobre la disfunció cognitiva associada a l'obesitat són limitats. La present tesi pretén descriure l'impacte del microbioma intestinal en la funció cognitiva en subjectes de mitjana edat amb obesitat. Amb aquesta finalitat, es va realitzar un estudi longitudinal prospectiu de casos i controls (n = 114) de subjectes amb i sense obesitat. Es va realitzar l'avaluació clínica, l'avaluació neurocognitiva de la memòria i el control inhibitori, el volum de la matèria grisa mitjançant ressonància magnètica, la metagenòmica fecal i la metabolòmica fecal/plasmàtica. Alguns paràmetres també es van mesurar en dues cohorts independents (n=24, n=970). El disseny experimental va incloure models de trasplantament de microbiota fecal d'humans a ratolins i, posteriorment, proves neuropsicològiques i anàlisi de l'expressió gènica de l'escorça prefrontal en els ratolins receptors. Els resultats apunten a l'existència d'un ecosistema de bacteris intestinals relacionat de manera diferent amb la funció de memòria i el control inhibitori en subjectes amb i sense obesitat. En aquest sentit, es van observar alteracions de la memòria i del control inhibitori en individus amb obesitat. Els patrons convergents i divergents d'espècies bacterianes, funcions i metabòlits circulants es van descriure longitudinalment i es van replicar principalment en cohorts independents. En particular, es van identificar alteracions en els aminoàcids aromàtics i les vies del metabolisme d'un carboni. El volum de matèria grisa de les àrees cerebrals implicades en la memòria i el control inhibitori es va associar de manera concordant amb el perfil del microbioma intestinal. Finalment, els dèficits cognitius presents en persones amb obesitat es van fenocopiar en els ratolins mitjançant el trasplantament de microbiota fecal, donant lloc a una disminució de les puntuacions semblants a la memòria i control inhibitori en ratolins. També es van observar associacions congruents amb les variables cognitives presents en ratolins i les espècies i funcions metagenòmiques del donant humà. A més, l'expressió de gens relacionats amb aminoàcids aromàtics i amb el metabolisme d’un carbono a l'escorça prefrontal dels ratolins es van vincular simultàniament a la cognició dels ratolins i amb l’ecosistema bacterià de la microbiota humana donant. En conjunt, aquestes troballes innovadores suggereixen xarxes hoste-microbioma bidireccionals que poden afectar la fisiologia del cervell i destaquen el potencial valor diagnòstic i terapèutic del microbioma intestinal per al deteriorament de la memòria i el control inhibitori, especialment en subjectes amb obesitatPrograma de Doctorat en Biologia Molecular, Biomedicina i Salu