Metabolomics signatures of acutely ill and short-term weight recovered women with anorexia nervosa

Multi-omics analysis reveals mechanisms of FMT in Enhancing antidepressant effects of SSRIs

OBJECTIVE

This study explores the behavioral and molecular biological impacts of Fecal Microbiota Transplantation (FMT) on depressive mice unresponsive to treatment with Selective Serotonin Reuptake Inhibitors (SSRIs).

METHODS

Healthy male C57BL/6 mice were used to establish a depression model through chronic restraint stress, treated with fluoxetine, and categorized into Response and Non-response groups. An FMT treatment was added to the Non-response group. Behavioral tests were conducted to assess symptoms of depression. The gut microbiome, plasma metabolites, and hippocampal tissue gene expression and function changes were analyzed using 16S rRNA gene sequencing, LC-MS, and RNA sequencing.

RESULTS

FMT significantly improved the depressive symptoms in SSRIs-resistant mice. There was a partial restoration in the diversity and structure of the gut microbiota in the FMT group. Compared to the Non-response group, significant changes were noted in the metabolomic profiles of the FMT group, identifying various differential metabolites. Functional annotations indicated that these metabolites are involved in multiple metabolic pathways. In the Non-response group, certain gene expression levels were significantly restored. GO and KEGG enrichment analyses revealed that these differential genes mainly involve cytokine activity, receptor signaling regulation, and NOD-like receptor signaling pathways. Joint analysis suggested that FMT may exert its effects through an increase in the abundance of g__Paraprevotella, leading to decreased baicalin content and increased Tal2 expression.

CONCLUSION

FMT has potential in improving depressive symptoms unresponsive to SSRIs treatment. Its mechanism may be related to the modulation of the gut microbiota and its metabolites, subsequently affecting gene expression.

MAAT: a new nonparametric Bayesian framework for incorporating multiple functional annotations in transcriptome-wide association studies

Transcriptome-wide association study (TWAS) has emerged as a powerful tool for translating the myriad variations identified by genome-wide association studies (GWAS) into regulated genes in the post-GWAS era. While integrating annotation information has been shown to enhance power, current annotation-assisted TWAS tools predominantly focus on epigenomic annotations. When including more annotations, the assumption of a positive correlation between annotation scores and SNPs' effect sizes, as adopted by current methods, often falls short. Here, we propose MAAT expanding the horizons of existing TWAS studies, generating a new model incorporating multiple annotations into TWAS and a new metric indicating the most important annotation.

Peripheral Biomarkers of Anorexia Nervosa: A Meta-Analysis

The pathogenesis of anorexia nervosa (AN) has been hypothesized to involve several biological systems. However, reliable biomarkers for AN have yet to be established. This study was aimed to identify statistically significant and clinically meaningful peripheral biomarkers associated with AN. A systematic literature search was conducted to identify studies published in English from inception until 30 June 2022. We conducted two-level random-effects meta-analyses to examine the difference between AN and comparison groups across 52 distinct biomarkers and found that acylated ghrelin, adrenocorticotropic hormone (ACTH), carboxy-terminal collagen crosslinks (CTX), cholesterol, cortisol, des-acyl ghrelin, ghrelin, growth hormone (GH), obestatin, and soluble leptin receptor levels were significantly higher in cases of AN compared with those in non-AN controls. Conversely, C-reactive protein (CRP), CD3 positive, CD8, creatinine, estradiol, follicle-stimulating hormone (FSH), free thyroxine, free triiodothyronine, glucose, insulin, insulin-like growth factor 1 (IGF-1), leptin, luteinizing hormone, lymphocyte, and prolactin levels were significantly lower in AN compared with those in non-AN controls. Our findings indicate that peripheral biomarkers may be linked to the pathophysiology of AN, such as processes of adaptation to starvation. Scientific investigation into peripheral biomarkers may ultimately yield breakthroughs in personalized clinical care for AN.

The Impact of Clinical Factors, Vitamin B12 and Total Cholesterol on Severity of Anorexia Nervosa: A Multicentric Cross-Sectional Study

Severe forms of Anorexia Nervosa (AN) are characterized by medical complications, psychiatric comorbidity, and high mortality. This study investigated potential associations between clinical/biological factors and the severity of AN, measured by the Body Mass Index (BMI). Red and white blood cells, hemoglobin, platelets, iron, vitamins D and B12, folate, and total cholesterol were measured in a mixed sample of 78 inpatients and outpatients. Linear regressions and one-way analyses of variance (ANOVAs) were carried out to evaluate the relationship between BMI and clinical/biochemical variables. BMI was significantly lower in hospitalized patients (F = 4.662; p = 0.034) and in those under pharmacological treatment (F = 5.733; p = 0.019) or poly-therapy (F = 5.635; p = 0.021). Higher vitamin B12 (β = -0.556, p < 0.001), total cholesterol (β = -0.320, p = 0.027), and later age at onset (with a trend towards significance) (β = -0.376, p = 0.058) were associated with a lower BMI. Increased total cholesterol and vitamin B12, later age at onset, current pharmacological treatment, and poly-therapy might be distinctive in patients with a lower BMI. In clinical practice, these findings may contribute to the early identification of AN patients at higher risk of developing complicated or chronic forms of the disorder. Further studies on larger samples are needed to identify potential predictive factors of AN severity in the framework of precision medicine.

Challenges and priorities for researching the gut microbiota in individuals living with anorexia nervosa

OBJECTIVE

The gut microbiota is implicated in several symptoms and biological pathways relevant to anorexia nervosa (AN). Investigations into the role of the gut microbiota in AN are growing, with a specific interest in the changes that occur in response to treatment. Findings suggest that microbial species may be associated with some of the symptoms common in AN, such as depression and gastrointestinal disturbances (GID). Therefore, researchers believe the gut microbiota may have therapeutic relevance. Whilst research in this field is rapidly expanding, the unique considerations relevant to conducting gut microbiota research in individuals with AN must be addressed.

METHOD

We provide an overview of the published literature investigating the relationship between the gut microbiota and symptoms and behaviors present in AN, discuss important challenges in gut microbiota research, and offer recommendations for addressing these. We conclude by summarizing research design priorities for the field to move forward.

RESULTS

Several ways exist to reduce participant burden and accommodate challenges when researching the gut microbiota in individuals with AN.

DISCUSSION

Recommendations from this article are foreseen to encourage scientific rigor and thoughtful protocol planning for microbiota research in AN, including ways to reduce participant burden. Employing such methods will contribute to a better understanding of the role of the gut microbiota in AN pathophysiology and treatment.

PUBLIC SIGNIFICANCE

The field of gut microbiota research is rapidly expanding, including the role of the gut microbiota in anorexia nervosa. Thoughtful planning of future research will ensure appropriate data collection for meaningful interpretation while providing a positive experience for the participant. We present current challenges, recommendations for research design and priorities to facilitate the advancement of research in this field.

Breastfeeding Is Associated with Lower Likelihood of Helicobacter Pylori Colonization in Babies, Based on a Prospective USA Maternal-Infant Cohort

BACKGROUND

Mother-to-child transmission of Helicobacter pylori (H. pylori) is the primary source of intrafamilial spread in early childhood in regions of high H. pylori prevalence. However, early-in-life H. pylori colonization and associated protective or risk factors have not been fully evaluated in lower prevalence regions, such as the USA.

AIMS

Therefore, from a well-characterized prospective US cohort, we selected women who provided fecal samples during pregnancy and had paired fecal samples from their babies up to 24 months postpartum. We evaluated maternal and baby factors associated with likelihood of H. pylori colonization in the babies. Fecal antigen testing was used to determine H. pylori status. We also evaluated the association between maternal breastmilk cytokines and H. pylori colonization in breastfed babies.

RESULTS

Among included mother-baby pairs (n = 66), H. pylori prevalence was 31.8% in mothers and 19.7% in their babies. Dominant breastfeeding (adjusted odds ratio [aOR] 0.17, 95% CI 0.03-0.98) and maternal IBD (aOR 0.05, 95% CI 0.01-0.27) were associated with significantly lower likelihood of H. pylori colonization among babies; no other clinical factors were associated with H. pylori colonization in the babies. Matrix metalloproteinase-10 (MMP-10) and tumor necrosis factor-related activation-induced cytokine expression were significantly higher in breastmilk of mothers with H. pylori positive vs negative babies.

CONCLUSIONS

Consistent with data from high H. pylori prevalence regions, our findings suggest dominant breastfeeding may protect against early H. pylori colonization. Downregulation of pro-inflammatory cytokines such as MMP-10 may be relevant in mediating this protection among breastfed babies, but more data are needed.

Integration of Metabolomic and Clinical Data Improves the Prediction of Intensive Care Unit Length of Stay Following Major Traumatic Injury

Recent advances in emergency medicine and the co-ordinated delivery of trauma care mean more critically-injured patients now reach the hospital alive and survive life-saving operations. Indeed, between 2008 and 2017, the odds of surviving a major traumatic injury in the UK increased by nineteen percent. However, the improved survival rates of severely-injured patients have placed an increased burden on the healthcare system, with major trauma a common cause of intensive care unit (ICU) admissions that last ≥10 days. Improved understanding of the factors influencing patient outcomes is now urgently needed. We investigated the serum metabolomic profile of fifty-five major trauma patients across three post-injury phases: acute (days 0–4), intermediate (days 5–14) and late (days 15–112). Using ICU length of stay (LOS) as a clinical outcome, we aimed to determine whether the serum metabolome measured at days 0–4 post-injury for patients with an extended (≥10 days) ICU LOS differed from that of patients with a short (<10 days) ICU LOS. In addition, we investigated whether combining metabolomic profiles with clinical scoring systems would generate a variable that would identify patients with an extended ICU LOS with a greater degree of accuracy than models built on either variable alone. The number of metabolites unique to and shared across each time segment varied across acute, intermediate and late segments. A one-way ANOVA revealed the most variation in metabolite levels across the different time-points was for the metabolites lactate, glucose, anserine and 3-hydroxybutyrate. A total of eleven features were selected to differentiate between <10 days ICU LOS vs. >10 days ICU LOS. New Injury Severity Score (NISS), testosterone, and the metabolites cadaverine, urea, isoleucine, acetoacetate, dimethyl sulfone, syringate, creatinine, xylitol, and acetone form the integrated biomarker set. Using metabolic enrichment analysis, we found valine, leucine and isoleucine biosynthesis, glutathione metabolism, and glycine, serine and threonine metabolism were the top three pathways differentiating ICU LOS with a p < 0.05. A combined model of NISS and testosterone and all nine selected metabolites achieved an AUROC of 0.824. Differences exist in the serum metabolome of major trauma patients who subsequently experience a short or prolonged ICU LOS in the acute post-injury setting. Combining metabolomic data with anatomical scoring systems allowed us to discriminate between these two groups with a greater degree of accuracy than that of either variable alone.

Serum Metabolomic and Lipidomic Profiling Reveals Novel Biomarkers of Efficacy for Benfotiamine in Alzheimer's Disease

Serum metabolomics and lipidomics are powerful approaches for discovering unique biomarkers in various diseases and associated therapeutics and for revealing metabolic mechanisms of both. Treatment with Benfotiamine (BFT), a thiamine prodrug, for one year produced encouraging results for patients with mild cognitive impairment and mild Alzheimer’s disease (AD). In this study, a parallel metabolomics and lipidomics approach was applied for the first exploratory investigation on the serum metabolome and lipidome of patients treated with BFT. A total of 315 unique metabolites and 417 lipids species were confidently identified and relatively quantified. Rigorous statistical analyses revealed significant differences between the placebo and BFT treatment groups in 25 metabolites, including thiamine, tyrosine, tryptophan, lysine, and 22 lipid species, mostly belonging to phosphatidylcholines. Additionally, 10 of 11 metabolites and 14 of 15 lipid species reported in previous literature to follow AD progression changed in the opposite direction to those reported to reflect AD progression. Enrichment and pathway analyses show that significantly altered metabolites by BFT are involved in glucose metabolism and biosynthesis of aromatic amino acids. Our study discovered that multiple novel biomarkers and multiple mechanisms that may underlie the benefit of BFT are potential therapeutic targets in AD and should be validated in studies with larger sample sizes.

Adverse Effects of Refeeding on the Plasma Lipidome in Young Individuals With Anorexia Nervosa?

OBJECTIVE

Refeeding is the cornerstone of anorexia nervosa (AN) treatment, but little is known regarding the optimal pace and dietary composition or possible adverse effects of current clinical practices. Plasma lipids may be a moderating factor underlying unfavorable refeeding effects in AN, such as an abnormal central body fat distribution. The objective of this study was to analyze the plasma lipidome in the acutely underweight state of AN before and after refeeding.

METHOD

Using high-throughput quantitative mass spectrometry-based shotgun lipidomics, we measured 13 lipid classes and 204 lipid species or subspecies in the plasma of young female patients with acute AN, before (n = 39) and after (n = 23) short-term weight restoration during an intensive inpatient refeeding program (median body mass index [BMI] increase = 26.4%), in comparison to those in healthy control participants (n = 37).

RESULTS

Before inpatient treatment, patients with AN exhibited increased concentrations of cholesterol and several other lipid classes. After refeeding, multiple lipid classes including cholesterol and ceramides, as well as certain ceramide species previously associated with obesity or overfeeding, showed increased concentrations, and a pattern of shorter and more saturated triacylgycerides emerged. A machine learning model trained to predict BMI based on the lipidomic profiles revealed a sizable overprediction in patients with AN after weight restoration.

CONCLUSION

The results point toward a profound lipid dysregulation with similarities to obesity and other features of the metabolic syndrome after short-term weight restoration. Thus, this study provides evidence for possible short-term adverse effects of current refeeding practices on the metabolic state and should inspire more research on nutritional interventions in AN.

Unveiling Metabolic Phenotype Alterations in Anorexia Nervosa through Metabolomics

Anorexia nervosa (AN) is a mental disorder characterized by an intense fear of weight gain that affects mainly young women. It courses with a negative body image leading to altered eating behaviors that have devastating physical, metabolic, and psychological consequences for the patients. Although its origin is postulated to be multifactorial, the etiology of AN remains unknown, and this increases the likelihood of chronification and relapsing. Thus, expanding the available knowledge on the pathophysiology of AN is of enormous interest. Metabolomics is proposed as a powerful tool for the elucidation of disease mechanisms and to provide new insights into the diagnosis, treatment, and prognosis of AN. A review of the literature related to studies of AN patients by employing metabolomic strategies to characterize the main alterations associated with the metabolic phenotype of AN during the last 10 years is described. The most common metabolic alterations are derived from chronic starvation, including amino acid, lipid, and carbohydrate disturbances. Nonetheless, recent findings have shifted the attention to gut-microbiota metabolites as possible factors contributing to AN development, progression, and maintenance. We have identified the areas of ongoing research in AN and propose further perspectives to improve our knowledge and understanding of this disease.

NMR- and MS-Based Untargeted Metabolomic Study of Stool and Serum Samples from Patients with Anorexia Nervosa

Anorexia nervosa (AN), a pathological restriction of food intake, leads to metabolic dysregulation. We conducted a metabolomics study to reveal changes caused by AN and the effect of hospital realimentation on metabolism. Both stool and serum from patients with AN and healthy controls were analyzed by NMR and MS. Statistical analysis revealed several altered biochemical and anthropometric parameters and 50 changed metabolites, including phospholipids, acylcarnitines, amino acids, derivatives of nicotinic acid, nucleotides, and energy metabolism intermediates. Biochemical and anthropometric parameters were correlated with metabolomic data. Metabolic changes in patients with AN described in our study imply serious system disruption defects, such as the development of inflammation and oxidative stress, changed free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels, a deficit of vitamins, muscle mass breakdown, and a decrease in ketone bodies as an important source of energy for the brain and heart. Furthermore, our data indicate only a very slight improvement after treatment. However, correlations of metabolomic results with body weight, interleukin 6, tumor necrosis factor α, fT4, and TSH might entail better prognoses and treatment effectiveness in patients with better system parameter status. Data sets are deposited in MassIVE: MSV000087713, DOI: 10.25345/C57R7X.

Serum profiling of anorexia nervosa: A 1H NMR-based metabolomics study

Our understanding of pathophysiological mechanisms underlying anorexia nervosa (AN) is incomplete. The aim was to conduct a metabolomics profiling of serum samples from women with AN (n = 65), women who have recovered from AN (AN-REC, n = 65), and age-matched healthy female controls (HC, n = 65). Serum concentrations of 21 metabolites were measured using proton nuclear magnetic resonance (¹H NMR). We used orthogonal partial least-squares discriminant analysis (OPLS-DA) modeling to assign group classification based on the metabolites. Analysis of variance (ANOVA) was used to test for metabolite concentration differences across groups. The OPLS-DA model could distinguish between the AN and HC groups (p = 9.05 × 10-11 R2Y = 0.36, Q2 = 0.37) and between the AN-REC and HC groups (p = 8.47 × 10-6, R2Y = 0.36, Q2 = 0.24,), but not between the AN and AN-REC groups (p = 0.63). Lower methanol concentration in the AN and AN-REC group explained most of the variance. Likewise, the strongest finding in the univariate analyses was lower serum methanol concentration in both AN and AN-REC compared with HC, which withstood adjustment for body mass index (BMI). We report for the first time lower serum concentrations of methanol in AN. The fact that low methanol was also found in recovered AN suggests that low serum concentration of methanol could either be trait marker or a scar effect of AN.

Current directions in biomarkers and endophenotypes for anorexia nervosa: A scoping review

There are currently no validated biomarkers for anorexia nervosa (AN), though recent literature suggests an increased research interest in this area. Biomarkers are objective, measurable indicators of illness that can be used to assist with diagnosis, risk assessment, and tracking of illness state. Related to biomarkers are endophenotypes, which are quantifiable phenomena that are distinct from symptoms and which link genes to manifest illness. In this scoping review, we sought to provide a summary of recent research conducted in the pursuit of biomarkers and endophenotypes for AN. The findings indicate that a number of possible biomarkers which can assess the presence or severity of AN independently of weight status, including psychophysical (e.g., eye-tracking) and biological (e.g., immune, endocrine, metabolomic, neurobiological) markers, are currently under investigation. However, this research is still in early phases and lacking in replication studies. Endophenotype research has largely been confined to the study of several neurocognitive features, with mixed evidence to support their classification as possible endophenotypes for the disorder. The study of biomarkers and endophenotypes in AN involves significant challenges due to confounding factors of illness-related sequalae, such as starvation. Future research in these areas must prioritise direct evaluation of the sensitivity, specificity and test-retest reliability of proposed biomarkers and enhanced control of confounding physical consequences of AN in the study of biomarkers and endophenotypes.

The Gut Microbiome and Metabolomics Profiles of Restricting and Binge-Purging Type Anorexia Nervosa

Alterations in the gut microbiome and fecal metabolites have been detected in anorexia nervosa (AN), but differences in those profiles between restricting AN (ANR) and binge-purging AN (ANBP) type have not been explored. We made a secondary analysis of our previous data concerning microbiome and metabolomics profiles of 17 ANR women, six ANBP women and 20 healthy controls (HC). Twelve fecal metabolites differentiating ANR patients, ANBP patients and HC were identified. Both patient groups showed decreased intra-individual bacterial richness with respect to healthy controls (HC). Compared to ANR subjects, ANBP patients had a significant increase in relative abundances of Bifidobacterium, Bifidobacteriaceae, Bifidobacteriales, and Eubacteriacae and a significant decrease in relative abundances of Odoribacter, Haemophilus, Pasteurellaceae, and Pasteurellales. The heatmaps of the relationships of selected fecal metabolites with microbial families showed different structures among the three groups, with the heatmap of ANBP patients being drastically different from that of HC, while that of ANR patients resulted more similar to HC. These findings, although preliminary because of the relatively small sample size, confirm the occurrence of different gut dysbiosis in ANR and ANBP and demonstrate different connections between gut microorganisms and fecal metabolites in the two AN types.

Current Aspects of the Role of Autoantibodies Directed Against Appetite-Regulating Hormones and the Gut Microbiome in Eating Disorders

The equilibrium and reciprocal actions among appetite-stimulating (orexigenic) and appetite-suppressing (anorexigenic) signals synthesized in the gut, brain, microbiome and adipose tissue (AT), seems to play a pivotal role in the regulation of food intake and feeding behavior, anxiety, and depression. A dysregulation of mechanisms controlling the energy balance may result in eating disorders such as anorexia nervosa (AN) and bulimia nervosa (BN). AN is a psychiatric disease defined by chronic self-induced extreme dietary restriction leading to an extremely low body weight and adiposity. BN is defined as out-of-control binge eating, which is compensated by self-induced vomiting, fasting, or excessive exercise. Certain gut microbiota-related compounds, like bacterial chaperone protein Escherichia coli caseinolytic protease B (ClpB) and food-derived antigens were recently described to trigger the production of autoantibodies cross-reacting with appetite-regulating hormones and neurotransmitters. Gut microbiome may be a potential manipulator for AT and energy homeostasis. Thus, the regulation of appetite, emotion, mood, and nutritional status is also under the control of neuroimmunoendocrine mechanisms by secretion of autoantibodies directed against neuropeptides, neuroactive metabolites, and peptides. In AN and BN, altered cholinergic, dopaminergic, adrenergic, and serotonergic relays may lead to abnormal AT, gut, and brain hormone secretion. The present review summarizes updated knowledge regarding the gut dysbiosis, gut-barrier permeability, short-chain fatty acids (SCFA), fecal microbial transplantation (FMT), blood-brain barrier permeability, and autoantibodies within the ghrelin and melanocortin systems in eating disorders. We expect that the new knowledge may be used for the development of a novel preventive and therapeutic approach for treatment of AN and BN.

Metabolomics profile of Japanese female patients with restricting-type anorexia nervosa

In this study, the serum metabolic profiles of 10 female patients with restricting type anorexia nervosa (ANR) were compared to those of 10 age-matched healthy female controls. While the levels of amino acids were lower among the patients than among the controls, the levels of uremic toxins, including p-cresyl sulfate (PCS), indole-3-acetic acid, and phenyl sulfate, were higher in ANR patients. The serum PCS levels correlated positively with the abundance of the Clostridium coccoides group or the C. leptum subgroup in the feces of patients, but not in those of controls. Collectively, these results indicate that the serum metabolic profiles of patients with ANR differ from those of healthy women in terms of both decreased amino acid levels and increased uremic toxins. Gut microbes including C. coccoides or C. leptum may be involved in such an increase in uremic toxins.

Evaluation of Metabolic Profiles of Patients with Anorexia Nervosa at Inpatient Admission, Short- and Long-Term Weight Regain-Descriptive and Pattern Analysis

Acute anorexia nervosa (AN) constitutes an extreme physiological state. We aimed to detect state related metabolic alterations during inpatient admission and upon short- and long-term weight regain. In addition, we tested the hypothesis that metabolite concentrations adapt to those of healthy controls (HC) after long-term weight regain. Thirty-five female adolescents with AN and 25 female HC were recruited. Based on a targeted approach 187 metabolite concentrations were detected at inpatient admission (T₀), after short-term weight recovery (T₁; half of target-weight) and close to target weight (T₂). Pattern hunter and time course analysis were performed. The highest number of significant differences in metabolite concentrations (N = 32) were observed between HC and T₁. According to the detected main pattern, metabolite concentrations at T₂ became more similar to those of HC. The course of single metabolite concentrations (e.g., glutamic acid) revealed different metabolic subtypes within the study sample. Patients with AN after short-term weight regain are in a greater “metabolic imbalance” than at starvation. After long-term weight regain, patients reach a metabolite profile similar to HC. Our results might be confounded by different metabolic subtypes of patients with AN.

Gut Feelings: How Microbiota Might Impact the Development and Course of Anorexia Nervosa

Anorexia nervosa (AN) can probably be regarded as a "model" for studying the interaction of nutrition with the gut-brain axis, which has drawn increased attention from researchers and clinicians alike. The gut microbiota influences somatic effects, such as energy extraction from food and body weight gain, as well as appetite, gut permeability, inflammation and complex psychological behaviors, such as depression or anxiety, all of which play important roles in AN. As nutrition is one of the main factors that influence the gut microbiota, nutritional restriction and selective eating in AN are likely influencing factors; however, nutritional rehabilitation therapy is surprisingly understudied. Here, we review the general mechanisms of the interactions between nutrition, the gut microbiota and the host that may be relevant to AN, paying special attention to the gut-brain axis, and we present the first specific findings in patients with AN and corresponding animal models. In particular, nutritional interventions, including food selection, supplements, and pre-, pro- and synbiotics that have the potential to influence the gut microbiota, are important research targets to potentially support future AN therapy.

Multi-omics data integration in anorexia nervosa patients before and after weight regain: A microbiome-metabolomics investigation

BACKGROUND & AIMS

We have recently reported specific fecal metabolomic changes in acute and short-term weight restored patients with anorexia nervosa (AN). In this study we explored the association between those metabolomic changes and patients' gut microbiome composition.

METHODS

The gut microbiome of AN women was sequenced in both the underweight phase (n = 21) and after short-term weight restoration (n = 16) and compared to that of 20 healthy women. According to a multi-omics approach, microbiome data were correlated with 49 relevant fecal metabolites previously characterized in our participants by an untargeted metabolomic procedure.

RESULTS

Compared to healthy women, AN patients showed a decreased intra-individual bacterial richness, an increased Bacteroidetes-to-Firmicutes abundance ratio and significant changes in the relative abundances of several bacteria at phylum, class, order, family and genus levels. These changes were observed in both the underweight and weight-restored condition. Moreover, the relationships among the 49 previously selected fecal metabolites and bacteria genera showed structures of different complexity among the 3 groups. In particular, a quarter of those relationships showed a divergent direction in the acutely ill patients with respect to the weight-restored ones or normal controls. Finally, in acutely ill patients 70% of those correlations showed a negative sign suggesting a prevalent metabolites consummation by gut microbiome.

CONCLUSIONS

These data confirm a profound perturbation in the gut microbiome composition of AN patients. Moreover, for the first time, they provide the evidence that in AN gut bacteria are connected with several fecal metabolites in a different way from normal controls and with divergent directions in the acute phase with respect to the weight-restored phase.