Weight Gain after Fecal Microbiota Transplantation in a Patient with Recurrent Underweight following Clinical Recovery from Anorexia Nervosa

Probiotic and prebiotic interventions in eating disorders: A narrative review

AIMS

The review aimed to summarise and discuss findings focused on therapeutic probiotic and prebiotic interventions in eating disorders (ED).

METHODS

Using PubMed/MEDLINE, Cochrane Library, and Web of Science all published studies were retrieved until February 2023, following PRISMA guidelines. From the 111 initial studies, 5 met the inclusion criteria for this review.

RESULTS

All studies included in this narrative review were focused on anorexia nervosa (AN). Three longitudinal, randomised, controlled trials aimed to evaluate interventions with probiotics (Lactobacillus reuteri, yoghurt with Lactobacillus, and Streptococcus) in children and adolescents. These studies primarily emphasised medical outcomes and anthropometric measures following the administration of probiotics. However, the findings yielded mixed results in terms of short-term weight gain or alterations in specific immunological parameters. With a lower level of evidence, supplementation with synbiotics (probiotic + prebiotic) has been associated with improvements in microbiota diversity and attenuation of inflammatory responses.

CONCLUSIONS

Research on probiotics and prebiotics in ED is limited, primarily focussing on anorexia nervosa (AN). Their use in AN regarding medical and anthropometric outcomes needs further confirmation and future research should be warranted to assess their impact on psychological and ED symptomatology, where there is a notable gap in the existing literature.

The role of gut fungi in Clostridioides difficile infection

Clostridioides difficile, the etiological agent of C. difficile infection (CDI), elicits a spectrum of diarrheal symptoms with varying severity and the potential to result in severe complications such as colonic perforation, pseudomembranous colitis, and toxic megacolon. The perturbation of gut microbiome, often triggered by antibiotic usage, represents the primary factor augmenting the risk of CDI. This underscores the significance of interactions between C. difficile and the microbiome in determining pathogen adaptability. In recent years, researchers have increasingly recognized the pivotal role played by intestinal microbiota in host health and its therapeutic potential as a target for medical interventions. While extensive evidence has been established regarding the involvement of gut bacteria in CDI, our understanding of symbiotic interactions between hosts and fungi within intestinal microbiota remains limited. Herein, we aim to comprehensively elucidate both composition and key characteristics of gut fungal communities that significantly contribute to CDI, thereby enhancing our comprehension from pharmacological and biomarker perspectives while exploring their prospective therapeutic applications for CDI.

Gut microbiota in relationship to diabetes mellitus and its late complications with a focus on diabetic foot syndrome: A review

Diabetes mellitus is a chronic disease affecting glucose metabolism. The pathophysiological reactions underpinning the disease can lead to the development of late diabetes complications. The gut microbiota plays important roles in weight regulation and the maintenance of a healthy digestive system. Obesity, diabetes mellitus, diabetic retinopathy, diabetic nephropathy and diabetic neuropathy are all associated with a microbial imbalance in the gut. Modern technical equipment and advanced diagnostic procedures, including xmolecular methods, are commonly used to detect both quantitative and qualitative changes in the gut microbiota. This review summarises collective knowledge on the role of the gut microbiota in both types of diabetes mellitus and their late complications, with a particular focus on diabetic foot syndrome.

Gut microbiota: A potential player in psychiatric symptoms during COVID-19

OBJECTIVES

This study aims to explore the potential interconnections among gut microbiota, COVID-19 infection, depression and anxiety disorder. Additionally, it tries to assess potential therapeutic interventions that may improve the dysbiosis of gut microbiota.

METHODS

To achieve these objectives, we reviewed existing literature, encompassing studies and critical reviews that intersect the domains of gut microbiota, COVID-19, depression and anxiety disorders.

RESULTS

The findings highlight a notable correlation between the dysbiosis of gut microbiota and psychiatric symptoms in the context of COVID-19. Specifically, there is a marked reduction in the populations of bacteria that generate anti-inflammatory short-chain fatty acids (SCFAs), alongside a rise in the prevalence of gut bacterial clusters linked to inflammatory processes. Furthermore, several potential treatment strategies were summarised for improving the dysbiosis.

CONCLUSIONS

Gut microbiota plays a significant role in psychiatric symptoms during COVID-19, which has significant implications for the study and prevention of psychiatric symptoms in major epidemic diseases.

Eating disorders: are gut microbiota to blame?

Gut microbiota could be involved in weight regulation and impact brain function via the gut-brain axis. Moreover, gut microbiota may impact the development of eating disorders (EDs) since they are characterized by weight-related concerns and symptoms and may represent a therapeutic target if future research can establish a causal link.

Streptococcus salivarius subsp. thermophilus CCFM1312 enhanced mice resilience to activity-based anorexia

Probiotic intervention, already showing promise in the treatment of various psychiatric disorders like depression, emerges as a potential therapy for anorexia nervosa (AN) with minimal side effects. In this study, we established an activity-based anorexia (ABA) model to probe the pathogenesis of AN and assess the impact of probiotics on ABA mice. ABA resulted in a compensatory increase in duodenal ghrelin levels, impairing the regulation of feeding and the brain reward system. Intervention with Streptococcus salivarius subsp. thermophilus CCFM1312 ameliorated these ABA-induced effects, and the activation of neurons in the nucleus tractus solitarius (NTS) was observed following probiotic administration, revealing the advantageous role of probiotics in AN through the vagus nerve. Furthermore, our metabolomics analysis of cecal contents unveiled that S. salivarius subsp. thermophilus CCFM1312 modulated gut microbiota metabolism and thereby regulated intestinal ghrelin levels.

Gut Microbiome Changes in Anorexia Nervosa: A Comprehensive Review

Anorexia nervosa (AN) remains a challenging condition in psychiatric management and its pathogenesis is not yet fully understood. An imbalance in the gut microbiota composition may contribute to its pathophysiology. This review aims to explore the link between the human gut microbiota and AN (objective 1) or refeeding syndrome in AN (objective 2). The online databases MEDLINE and PsycINFO were searched for relevant studies. A total of 14 studies met the inclusion and exclusion criteria and only answered objective 1. A total of 476 AN patients, 554 healthy-weight (HC) controls, and 0 patients with other psychiatric disorders were included. Compared to HC, there were consistently reduced abundances of Faecalibacterium prausnitzii and Roseburia inulinivorans, and increased Methanobrevibacter smithii, in AN patients. Changes in alpha diversity were inconsistent, while beta diversity increased in four of six studies. Our model suggests that an imbalance in gut microbiota composition leads to reduced short-chain fatty acids, contributing to a proinflammatory state in AN, which is also common in other psychiatric comorbidities. Microbial changes may also contribute to the semistarvation state through endocrine changes and altered energy utilization.

From gut microbiota to brain: implications on binge eating disorders

The prevalence of eating disorders has been increasing over the last 50 years. Binge eating disorder (BED) and bulimia nervosa (BN) are two typical disabling, costly and life-threatening eating disorders that substantially compromise the physical well-being of individuals while undermining their psychological functioning. The distressing and recurrent episodes of binge eating are commonly observed in both BED and BN; however, they diverge as BN often involves the adoption of inappropriate compensatory behaviors aimed at averting weight gain. Normal eating behavior is coordinated by a well-regulated trade-off between intestinal and central ingestive mechanism. Conversely, despite the fact that the etiology of BED and BN remains incompletely resolved, emerging evidence corroborates the notion that dysbiosis of gastrointestinal microbiome and its metabolites, alteration of gut-brain axis, as well as malfunctioning central circuitry regulating motivation, execution and reward all contribute to the pathology of binge eating. In this review, we aim to outline the current state of knowledge pertaining to the potential mechanisms through which each component of the gut-brain axis participates in binge eating behaviors, and provide insight for the development of microbiome-based therapeutic interventions that hold promise in ameliorating patients afflicted with binge eating disorders.

Persistence of gut dysbiosis in individuals with anorexia nervosa

Recent evidence suggests a crucial role of the gut microbiota in the pathogenesis of anorexia nervosa (AN). In this study, we carried out a series of multiple analyses of the gut microbiota of hospitalized individuals with AN over three months using 16S or 23S rRNA-targeted reverse transcription-quantitative polymerase chain reaction (PCR) technology (YIF-SCAN®), which is highly sensitive and enables the precise quantification of viable microorganisms. Despite the weight gain and improvements in psychological features observed during treatment, individuals with AN exhibited persistent gut microbial dysbiosis over the three-month duration. Principal component analysis further underscored the distinct microbial profile of individuals with AN, compared with that of age-matched healthy women at all time points. Regarding the kinetics of bacterial detection, the detection rate of Lactiplantibacillus spp. significantly increased after inpatient treatment. Additionally, the elevation in the Bifidobacterium counts during inpatient treatment was significantly correlated with the subsequent body weight gain after one year. Collectively, these findings suggest that gut dysbiosis in individuals with AN may not be easily restored solely through weight gain, highlighting the potential of therapeutic interventions targeting microbiota via dietary modifications or live biotherapeutics.

The impact of aging-induced gut microbiome dysbiosis on dendritic cells and lung diseases

Aging is an inevitable natural process that impacts every individual, and understanding its effect on the gut microbiome and dendritic cell (DC) functionality in elderly subjects is crucial. DCs are vital antigen-presenting cells (APCs) that orchestrate the immune response, maintaining immune tolerance to self-antigens and bridging innate and adaptive immunity. With aging, there is a shift toward nonspecific innate immunity, resulting in a decline in adaptive immune responses. This alteration raises significant concerns about managing the health of an elderly population. However, the precise impact of aging and microbiome changes on DC function and their implications in lung-associated diseases remain relatively understudied. To illuminate this subject, we will discuss recent advancements in understanding the connections between aging, gut dysbiosis, DCs, and lung diseases. Emphasizing the key concepts linking age-related gut microbiome changes and DC functions, we will focus on their relevance to overall health and immune response in elderly individuals. This article aims to improve our understanding of the intricate relationship between aging, gut microbiome, and DCs, potentially benefiting the management of age-associated diseases and promoting healthy aging.

[Eating disorders - what the gastroenterologist needs to know]

Eating disorders are potentially life-threatening disorders that go along with severe psychiatric and somatic comorbidities. It is expected that the number of patients will dramatically increase in the post COVID-19 pandemic era.Four main eating disorders are mentioned in the Diagnostic and Statistical Manual of Mental Disorders 5 (DSM-5) and the International Classification of Diseases 11 (ICD-11): anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED) und avoidant restrictive food intake disorder (ARFID). Many traditional assumptions in eating disorders are currently challenged due to recent research results. The gastroenterologist is usually not the first point of contact for patients with eating disorders. However, he is crucial, especially in the management of gastroenterologic complications of eating disorders.Focus of the overview will be on relevant gastroenterologic aspects and less on the psychiatric treatment. Basics of the most common eating disorders will be repeated, opportunities in diagnosing an eating disorder and the most relevant gastroenterologic complications will be described. Obesity and its management, an entity that often goes along with an eating disorder, is not in the spotlight of the review.

[Fecal Microbiota Transplants in the Context of (Child and Adolescent) Psychiatric Disorders]

Fecal Microbiota Transplants in the Context of (Child and Adolescent) Psychiatric Disorders Abstract: There has recently been a significant increase in interest in gut microbiota and its interaction with the brain (gut-brain axis). Not only are the findings of microbiome research interesting for basic scientists, they also offer relevant insights for clinical practice. A causal relationship between gut microbiome and various somatic diseases such as diabetes mellitus, inflammatory bowel diseases, and obesity as well as psychiatric diseases such as major depression, anxiety disorders, and eating disorders seems plausible. To study the causal relationship of intestinal bacteria with individual phenotypes, researchers apply so-called stool transplantations (fecal microbiota transplantations) in the preclinical context. For this purpose, they transfer microbiota samples from patients into laboratory animals to observe possible changes in phenotype. In the clinical context, fecal microbiota transplantation is already being used with therapeutic intentions for selected diseases, for example, recurrent infections with Clostridioides difficile or inflammatory bowel diseases; they have already become part of the official clinical guidelines for C. difficile. For many other diseases, however, including mental illnesses, the potential of using fecal transplantations for therapeutic purposes is still being explored. Previous findings suggest that the intestinal microbiome, particularly fecal microbiota transplantations, represent a promising starting point for new therapeutic approaches.

From-Toilet-to-Freezer: A Review on Requirements for an Automatic Protocol to Collect and Store Human Fecal Samples for Research Purposes

The composition, viability and metabolic functionality of intestinal microbiota play an important role in human health and disease. Studies on intestinal microbiota are often based on fecal samples, because these can be sampled in a non-invasive way, although procedures for sampling, processing and storage vary. This review presents factors to consider when developing an automated protocol for sampling, processing and storing fecal samples: donor inclusion criteria, urine-feces separation in smart toilets, homogenization, aliquoting, usage or type of buffer to dissolve and store fecal material, temperature and time for processing and storage and quality control. The lack of standardization and low-throughput of state-of-the-art fecal collection procedures promote a more automated protocol. Based on this review, an automated protocol is proposed. Fecal samples should be collected and immediately processed under anaerobic conditions at either room temperature (RT) for a maximum of 4 h or at 4 °C for no more than 24 h. Upon homogenization, preferably in the absence of added solvent to allow addition of a buffer of choice at a later stage, aliquots obtained should be stored at either -20 °C for up to a few months or -80 °C for a longer period-up to 2 years. Protocols for quality control should characterize microbial composition and viability as well as metabolic functionality.

Gut-Associated Lymphatic Tissue in Food-Restricted Rats: Influence of Refeeding and Probiotic Supplementation

Anorexia nervosa (AN) is a severe and often chronic eating disorder that leads to alterations in the gut microbiome, which is known to influence several processes, such as appetite and body weight regulation, metabolism, gut permeability, inflammation, and gut-brain interactions. Using a translational activity-based anorexia (ABA) rat model, this study examined the effect of chronic food starvation, as well as multistrain probiotic supplementation and refeeding, on the structure of the gut and gut-associated lymphatic tissue (GALT). Our results indicated that ABA had an atrophic influence on intestinal morphology and increased the formation of GALT in the small bowel and colon. Higher formation of GALT in ABA rats appeared to be reversible upon application of a multistrain probiotic mixture and refeeding of the starved animals. This is the first time that increased GALT was found following starvation in the ABA model. Our results underscore a potential role of gut inflammatory alterations in the underlying pathophysiology of AN. Increased GALT could be linked to the gut microbiome, as probiotics were able to reverse this finding. These results emphasize the role of the microbiome-gut-brain axis in the pathomechanisms of AN and point to probiotics as potentially beneficial addendum in the treatment of AN.

Novel ketamine and zinc treatment for anorexia nervosa and the potential beneficial interactions with the gut microbiome

Anorexia nervosa (AN) is a severe illness with diverse aetiological and maintaining contributors including neurobiological, metabolic, psychological, and social determining factors. In addition to nutritional recovery, multiple psychological and pharmacological therapies and brain-based stimulations have been explored; however, existing treatments have limited efficacy. This paper outlines a neurobiological model of glutamatergic and γ-aminobutyric acid (GABA)-ergic dysfunction, exacerbated by chronic gut microbiome dysbiosis and zinc depletion at a brain and gut level. The gut microbiome is established early in development, and early exposure to stress and adversity contribute to gut microbial disturbance in AN, early dysregulation to glutamatergic and GABAergic networks, interoceptive impairment, and inhibited caloric harvest from food (e.g., zinc malabsorption, competition for zinc ions between gut bacteria and host). Zinc is a key part of glutamatergic and GABAergic networks, and also affects leptin and gut microbial function; systems dysregulated in AN. Low doses of ketamine in conjunction with zinc, could provide an efficacious combination to act on NMDA receptors and normalise glutamatergic, GABAergic and gut function in AN.

Comparison of the Activity of Fecal Enzymes and Concentration of SCFA in Healthy and Overweight Children

In modern societies obesity has become a serious issue which must be urgently addressed. The health implications of neglected obesity are substantial, as not only does it affect individuals' everyday lives, but it also leads to significantly increased mortality due to the development of several disorders such as type-2 diabetes, cardiovascular diseases, cancers, and depression. The objective of this research was to investigate the alterations in selected health markers caused by overweight and obesity in children. The measured parameters were the activity of the fecal enzymes, the concentration of short-chain fatty acids (SCFAs), and the concentration of branched-chain fatty acids (BCFAs). The activity of the fecal enzymes, specifically α-glucosidase, α-galactosidase, β-glucosidase, β-galactosidase, and β-glucuronidase, was determined using spectrophotometry at a wavelength of 400 nm. Furthermore, concentrations of lactic acid, SCFAs (formic, acetic, propionic, butyric, and valeric acids), and BCFAs (isobutyric and isovaleric acids) were determined using the HPLC method. The obtained results reveal that obese children have different fecal enzyme activity and a different profile of fatty acids from children of normal weight. The group of obese children, when compared to children of normal weight, had increased concentrations of BCFAs (p < 0.05) and higher activity of potentially harmful enzymes such as β-glucosidase and β-glucuronidase (p < 0.05). In comparison, children of normal weight exhibited significantly increased concentrations of lactic acid and SCFAs (especially formic and butyric acids) (p < 0.05). Furthermore, their α-glucosidase and α-galactosidase activity were higher when compared to the group of obese children (p < 0.05). These results suggest that the prevalence of obesity has a significant impact on metabolites produced in the gastrointestinal tract, which might result in a higher chance of developing serious diseases.

Gut microbiome-brain interactions in anorexia nervosa: Potential mechanisms and regulatory strategies

Anorexia nervosa (AN) is a psychiatric disorder characterised by malnutrition, fear of weight gain, and body image disturbances. The aetiology of AN is complex, and may involve environmental factors, genetic factors, and biochemical factors, with the latter meaning that AN may be closely associated with neurons, neurotransmitters, and hormones related to appetite and emotional regulation. In addition, an increasing number of studies have shown there is a link between the intestinal microbiota and psychiatric disorders, such as depression. However, few studies and reviews have focused on AN and gut microbes. Accordingly, in this review, we examine the potential pathogenesis of AN in terms of changes in the gut microbiota and its metabolites, and their effects on AN. The neurobiological function of the nervous system in relation to AN are also been mentioned. Furthermore, we suggest future research directions for this field, and note that probiotics may be developed for use as dietary supplements to help alleviate AN in patients.

Anorexia nervosa and microbiota: systematic review and critical appraisal

PURPOSE

Recent studies have reported a gut microbiota imbalance or dysbiosis associated with anorexia nervosa (AN), which has prompted an appraisal of its aetiological role, and the reformulation of AN as a metabo-psychiatric disorder. Thus, the aim of this paper was to critically review the current scientific findings regarding the role of microbiota in anorexia nervosa.

METHODS

A systematic study of peer-reviewed literature published in four databases between 2009 and 2022 was conducted according to PRISMA guidelines. Both human and animal studies were included.

RESULTS

A total of 18 studies were included. In animal models, both the preclinical and clinical findings were inconsistent regarding microbiota composition, faecal metabolite concentrations, and the effects of human faecal microbiota transplants.

CONCLUSION

The methodological limitations, lack of standardisation, and conceptual ambiguity hinder the analysis of microbiota as a key explanatory factor for AN.

LEVEL OF EVIDENCE

Level I, systematic review.

Gastrointestinal symptoms, gut microbiome, probiotics and prebiotics in anorexia nervosa: A review of mechanistic rationale and clinical evidence

Recent research has revealed the pivotal role that the gut microbiota might play in psychiatric disorders. In anorexia nervosa (AN), the gut microbiota may be involved in pathophysiology as well as in the gastrointestinal (GI) symptoms commonly experienced. This review collates evidence for the potential role of gut microbiota in AN, including modulation of the immune system, the gut-brain axis and GI function. We examined studies comparing gut microbiota in AN with healthy controls as well as those looking at modifications in gut microbiota with nutritional treatment. Changes in energy intake and nutritional composition influence gut microbiota and may play a role in the evolution of the gut microbial picture in AN. Additionally, some evidence indicates that pre-morbid gut microbiota may influence risk of developing AN. There appear to be similarities in gut microbial composition, mechanisms of interaction and GI symptoms experienced in AN and other GI disorders such as inflammatory bowel disease and functional GI disorders. Probiotics and prebiotics have been studied in these disorders showing therapeutic effects of probiotics in some cases. Additionally, some evidence exists for the therapeutic benefits of probiotics in depression and anxiety, commonly seen as co-morbidities in AN. Moreover, preliminary evidence for the use of probiotics in AN has shown positive effects on immune modulation. Based on these findings, we discuss the potential therapeutic role for probiotics in ameliorating symptoms in AN.

Is fecal microbiota transplantation a useful therapeutic intervention for psychiatric disorders? A narrative review of clinical and preclinical evidence

The therapeutic management of psychiatric disorders is currently confronted with a critical need to find new therapeutic interventions due to the high rates of non-responsivity or low responsivity in the key pathologies, e.g. schizophrenia spectrum disorders, alcohol use disorders, or major depressive disorder. The modulation of intestinal microbiota has been explored in various organic and psychiatric dysfunctions, with different degrees of success. However, this type of intervention may represent a helpful add-on at a conceptual level since it does not associate negative pharmacokinetics interactions, significant adverse events, or risk for non-adherence in the long term. Oral administration of pre-, pro-, or synbiotics, and especially the treatment with fecal microbiota transplantation (FMT), are methods still in their early research phase for patients with psychiatric disorders, therefore an exploration of data regarding the potential benefits and adverse events of FMT was considered necessary. In order to accomplish this purpose, the available results of research dedicated to each category of psychiatric disorders, starting with depressive and anxiety disorders, continuing with schizophrenia, substance use disorders, and finishing with disorders diagnosed during childhood, were presented in this paper. Seven clinical trials, 16 preclinical studies, three meta-analyses/systematic reviews, and six case reports, all of these representing ten distinct categories of psychiatric disorders or manifestations, have been reviewed. Mood disorders, anxiety disorders, and alcohol dependence have been the most extensively investigated clinical entities from the FMT efficacy and tolerability perspective, and reviewed data are generally promising. Based on the current status of research, FMT may be considered a helpful intervention in specific psychiatric pathologies. Still, this review showed that most of the information is derived from entirely preclinical studies. Therefore, clinical trials with sound methodology and more participants are needed to clarify FMT's benefits and risks in psychiatric disorders.

Plasma Concentrations of Short-Chain Fatty Acids in Active and Recovered Anorexia Nervosa

Anorexia nervosa (AN) is one of the most lethal psychiatric disorders. To date, we lack adequate knowledge about the (neuro)biological mechanisms of this disorder to inform evidence-based pharmacological treatment. Gut dysbiosis is a trending topic in mental health, including AN. Communication between the gut microbiota and the brain is partly mediated by metabolites produced by the gut microbiota such as short-chain fatty acids (SCFA). Previous research has suggested a role of SCFA in weight regulation (e.g., correlations between specific SCFA-producing bacteria and BMI have been demonstrated). Moreover, fecal SCFA concentrations are reported to be altered in active AN. However, data concerning SCFA concentrations in individuals who have recovered from AN are limited. In the present study, we analyzed and compared the plasma concentrations of seven SCFA (acetic-, butyric-, formic-, isobutyric-, isovaleric-, propionic-, and succinic acid) in females with active AN (n = 109), recovered from AN (AN-REC, n = 108), and healthy-weight age-matched controls (CTRL, n = 110), and explored correlations between SCFA concentrations and BMI. Significantly lower plasma concentrations of butyric, isobutyric-, and isovaleric acid were detected in AN as well as AN-REC compared with CTRL. We also show significant correlations between plasma concentrations of SCFA and BMI. These results encourage studies evaluating whether interventions directed toward altering gut microbiota and SCFA could support weight restoration in AN.

A critical analysis of eating disorders and the gut microbiome

The gut microbiota, also known as our "second brain" is an exciting frontier of research across a multitude of health domains. Gut microbes have been implicated in feeding behaviour and obesity, as well as mental health disorders including anxiety and depression, however their role in the development and maintenance of eating disorders (EDs) has only recently been considered. EDs are complex mental health conditions, shaped by a complicated interplay of factors. Perhaps due to an incomplete understanding of the etiology of EDs, treatment remains inadequate with affected individuals likely to face many relapses. The gut microbiota may be a missing piece in understanding the etiology of eating disorders, however more robust scientific inquiry is needed in the field before concrete conclusions can be made. In this spotlight paper, we critically evaluate what is known about the bi-directional relationship between gut microbes and biological processes that are implicated in the development and maintenance of EDs, including physiological functioning, hormones, neurotransmitters, the central nervous system, and the immune system. We outline limitations of current research, propose concrete steps to move the field forward and, hypothesize potential clinical implications of this research. Our gut is inhabited by millions of bacteria which have more recently been referred to as "our second brain". In fact, these microbes are thought to play a role in ED behaviour, associated anxiety and depression, and even affect our weight. Recent research has dove into this field with promising findings that have the potential to be applied clinically to improve ED recovery. The present paper discusses what is known about the gut microbiome in relation to EDs and the promising implications that leveraging this knowledge, through fecal microbiome transplants, probiotics, and microbiome-directed supplemental foods, could have on ED treatment.

Whole-Genome Shotgun Metagenomic Sequencing Reveals Distinct Gut Microbiome Signatures of Obese Cats

Overweight and obesity are growing health problems in domestic cats, increasing the risks of insulin resistance, lipid dyscrasias, neoplasia, cardiovascular disease, and decreasing longevity. The signature of obesity in the feline gut microbiota has not been studied at the whole-genome metagenomic level. We performed whole-genome shotgun metagenomic sequencing in the fecal samples of eight overweight/obese and eight normal cats housed in the same research environment. We obtained 271 Gbp of sequences and generated a 961-Mbp de novo reference contig assembly, with 1.14 million annotated microbial genes. In the obese cat microbiome, we discovered a significant reduction in microbial diversity (P < 0.01) and Firmicutes abundance (P = 0.005), as well as decreased Firmicutes/Bacteroidetes ratios (P = 0.02), which is the inverse of obese human/mouse microbiota. Linear discriminant analysis and quantitative PCR (qPCR) validation revealed significant increases of Bifidobacterium sp., Olsenella provencensis, Dialister sp.CAG:486, and Campylobacter upsaliensis as the hallmark of obese microbiota among 400 enriched species, whereas 1,525 bacterial species have decreased abundance in the obese microbiome. Phascolarctobacterium succinatutens and an uncharacterized Erysipelotrichaceae bacterium are highly abundant (>0.05%) in the normal gut with over 400-fold depletion in the obese microbiome. Fatty acid synthesis-related pathways are significantly overrepresented in the obese compared with the normal cat microbiome. In conclusion, we discovered dramatically decreased microbial diversity in obese cat gut microbiota, suggesting potential dysbiosis. A panel of seven significantly altered, highly abundant species can serve as a microbiome indicator of obesity. Our findings in the obese cat microbiome composition, abundance, and functional capacities provide new insights into feline obesity.

IMPORTANCE Obesity affects around 45% of domestic cats, and licensed drugs for treating feline obesity are lacking. Physical exercise and calorie restrictions are commonly used for weight loss but with limited efficacy. Through comprehensive analyses of normal and obese cat gut bacteria flora, we identified dramatic shifts in the obese gut microbiome, including four bacterial species significantly enriched and two species depleted in the obese cats. The key bacterial community and functional capacity alterations discovered from this study will inform new weight management strategies for obese cats, such as evaluations of specific diet formulas that alter the microbiome composition, and the development of prebiotics and probiotics that promote the increase of beneficial species and the depletion of obesity-associated species. Interestingly, these bacteria identified in our study were also reported to affect the weight loss success in human patients, suggesting translational potential in human obesity.

The Influence of Nutrition on Intestinal Permeability and the Microbiome in Health and Disease

The leakage of the intestinal barrier and the disruption of the gut microbiome are increasingly recognized as key factors in different pathophysiological conditions, such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), chronic liver diseases, obesity, diabetes mellitus, types of cancer, and neuropsychiatric disorders. In this study, the mechanisms leading to dysbiosis and "leaky gut" are reviewed, and a short summary of the current knowledge regarding different diseases is provided. The simplest way to restore intestinal permeability and the microbiota could be ideal nutrition. Further therapeutic options are also available, such as the administration of probiotics or postbiotics or fecal microbiota transplantation.

Anorexia nervosa: Outpatient treatment and medical management

Anorexia nervosa (AN) is a disabling, costly and potentially deadly illness. Treatment failure and relapse are common after completing treatment, and a substantial proportion of patients develop severe and enduring AN. The time from AN debut to the treatment initiation is normally unreasonably long. Over the past 20 years there has been empirical support for the efficacy of several treatments for AN. Moreover, outpatient treatment with family-based therapy or individual psychotherapy is associated with good outcomes for a substantial proportion of patients. Early intervention improves outcomes and should be a priority for all patients. Outpatient treatment is usually the best format for early intervention, and it has been demonstrated that even patients with severe or extreme AN can be treated as outpatients if they are medically stable. Inpatient care is more disruptive, more costly, and usually has a longer waiting list than does outpatient care. The decision as to whether to proceed with outpatient treatment or to transfer the patient for inpatient therapy may be difficult. The core aim of this opinion review is to provide the knowledge base needed for performing safe outpatient treatment of AN. The scientific essentials for outpatient treatment are described, including how to assess and manage the medical risks of AN and how to decide when transition to inpatient care is indicated. The following aspects are discussed: early intervention, outpatient treatment of AN, including outpatient psychotherapy for severe and extreme AN, how to determine when outpatient treatment is safe, and when transfer to inpatient healthcare is indicated. Emerging treatments, ethical issues and outstanding research questions are also addressed.

Anorexia nervosa and gut microbiome: implications for weight change and novel treatments

INTRODUCTION

Host-microbiota interactions may be involved in many physical and psychological functions ranging from the digestion of food, maintenance of immune homeostasis, to the regulation of mood and cognition. Microbiome dysbiosis has been consistently described in many diseases. The pathogenesis and weight regulation mechanism in anorexia nervosa (AN) also seem to be implicated in the dynamic bidirectional adjustment of the microbiota-gut-brain axis. This review aims at elucidating this relationship.

AREA COVERED

This review starts with a description of pathogenic gut-brain pathways. Next, we focus on the latest research on the associations between gut microbiota and weight change in the condition of AN. The strategies to alter the intestinal microbiome for the treatment of this disorder are discussed, including dietary, probiotics, prebiotics, synbiotics, and fecal microbiota transplantation.

EXPERT OPINION

Gut microbiome is inextricably linked to AN. It may regulate weight gain in the process of refeeding via the microbiota-gut-brain axis, while the specific mechanism has yet to be clearly established. In the future, a better understanding of gut microbiome could have implications for developing microbiome-based prevention, diagnostics and therapies.

Fecal microbiota transplantation does not alter bacterial translocation and visceral adipose tissue inflammation in individuals with obesity

AIMS

Visceral adipose tissue inflammation is a fundamental mechanism of insulin resistance in obesity and type 2 diabetes. Translocation of intestinal bacteria has been suggested as a driving factor for the inflammation. However, although bacterial DNA was detected in visceral adipose tissue of humans with obesity, it is unclear to what extent this is contamination or whether the gut microbiota is causally involved. Effects of fecal microbiota transplantation (FMT) on bacterial translocation and visceral adipose tissue inflammation in individuals with obesity and insulin resistance were assessed.

MATERIAL AND METHODS

Eight individuals with clinically severe obesity (body mass index [BMI] >35 kg/m2) and metabolic syndrome received lean donor FMT 4 weeks prior to elective bariatric surgery. The participants were age-, sex-, and BMI-matched to 16 controls that underwent no fecal transplantation. Visceral adipose tissue was collected during surgery. Bacterial translocation was assessed by 16S rRNA gene sequencing of adipose tissue and feces. Pro-inflammatory cytokine expression and histopathological analyses of visceral adipose tissue were performed to assess inflammation.

RESULTS

Fecal microbiota transplantation significantly altered gut microbiota composition. Visceral adipose tissue contained a very low quantity of bacterial DNA in both groups. No difference in visceral bacterial DNA content between groups was observed. Also, visceral expression of pro-inflammatory cytokines and macrophage infiltration did not differ between groups. No correlation between inflammatory tone and bacterial translocation was observed.

CONCLUSIONS

Visceral bacterial DNA content and level of inflammation were not altered upon FMT. Thus, bacterial translocation may not be the main driver of visceral adipose tissue inflammation in obesity.

Adverse events of fecal microbiota transplantation: a meta-analysis of high-quality studies

BACKGROUND

Fecal microbiota transplantation (FMT) has shown excellent efficacy in treating Clostridioides difficile infection, as well as promise in several other diseases. The heightened interest is accompanied by concerns over adverse events (AE) and safety. To further understand that in FMT, we performed a systematic review of the literature and a meta-analysis of high-quality, prospective randomized controlled trials FMT.

METHODS

Studies were selected based on predefined exclusion criteria and were assessed for quality. Only prospective, randomized, controlled studies of high quality were included in the final analysis. Data were extracted on demographics, AE, indication, delivery method and follow-up duration.

RESULTS

Out of 334 articles reviewed, 9 high quality studies with 756 FMTs were selected for final analysis. The pooled rate of AE was 39.3% (95% confidence interval [CI] 0.19-0.642) as they were reported by 112 patients who received FMT. The SAE rate was 5.3% (95%CI 3.1-8.8%). The most common AE reported was abdominal pain, followed by diarrhea. The most common SAE was Clostridium difficile infection. Upper gastrointestinal tract delivery was associated with a higher rate of total AE, but not SAE.

CONCLUSIONS

Based on the selected studies, the AE rate of FMT is 39.3%, with most AE being mild and self-limiting. SAE were uncommon at 5.3%, and many were only possibly related to the FMT. Adherence to standardized reporting of AE as well as longitudinal studies and registries will help further clarify the safety of FMT in the future.

[The Gut Microbiome and Its Clinical Implications in Anorexia Nervosa]

The Gut Microbiome and Its Clinical Implications in Anorexia Nervosa Abstract. The diverse interactions of the gut microbiome with the metabolism, the immune system, and the brain of the host are increasingly becoming to the forefront of relevant research. Studies suggest a connection between an altered intestinal microbiome and somatic diseases, such as colitis ulcerosa, Crohn's disease, and diabetes, as well as mental illnesses such as anxiety and depression. Patients with anorexia nervosa (AN) also show significant changes in their gut microbiome which seem to be associated, among other things, with a different energy uptake from food, immunological and inflammatory processes, genetic predisposition, hormonal changes, and possibly increased intestinal permeability. In rats, stool transplantation from patients with AN resulted in decreased appetite and weight as well as anxious and compulsive behavior. In this review, we summarize the possible mechanisms of interaction between the microbiome and the host, and present initial findings on the microbiome in AN. Research on nutritional interventions, for example, with prebiotics and probiotics or nutritional supplements such as omega-3 fatty acids, which aim to positively influence the intestinal microbiome, could lead to additional treatment options in the therapy of patients with AN.

Reframing anorexia nervosa as a metabo-psychiatric disorder

Anorexia nervosa (AN) is a serious and often fatal illness. Despite decades of research, investigators have failed to adequately advance our understanding of the biological aspects of AN that could inform the development of effective interventions. Genome-wide association studies are revealing the important role of metabolic factors in AN, and studies of the gastrointestinal tract are shedding light on disruptions in enteric microbial communities and anomalies in gut morphology. In this opinion piece, we review the state of the science through the lens of the clinical presentation of illness. We project how the integration of rigorous science in genomics and microbiology, in collaboration with experienced clinicians, has the potential to markedly enhance treatment outcome via precision interventions.

The intestinal microbiota and anorexia nervosa: cause or consequence of nutrient deprivation

The intestinal microbiota is a diverse microbial community that colonizes the gastrointestinal tract of animals. Abnormal changes in intestinal microbiota has been associated with multiple diseases including inflammatory bowel diseases and obesity; however, emerging evidence suggests a role for the gut microbiota in anxiety and depression via the gut-brain axis. As this microbial community is associated with weight dysregulation and host behavior it is not surprising that the intestinal microbiota may have a role to play in anorexia nervosa (AN). In this review we examine recent studies linking the gut microbiota with nutrition, psychopathology, and ultimately AN. We also review potential gut microbiota-based therapies for AN.

Small intestinal flora graft alters fecal flora, stool, cytokines and mood status in healthy mice

Transplantation of microbiota from small intestine, not large intestine, of healthy mice exerts obvious effects on healthy recipients, bringing a new perspective on gut flora transplantation.

Fecal microbiota transplantation is widely used. Large intestinal microbiota (LIM) is more similar to fecal microbiota than small intestinal microbiota (SIM). The SIM communities are very different from those of LIM. Therefore, SIM transplantation (SIMT) and LIM transplantation (LIMT) might exert different influences. Here, healthy adult male C57Bl/6 mice received intragastric SIMT, LIMT, or sterile PBS administration. Microbiota graft samples were collected from small/large intestine of healthy mice of the same age, sex, and strain background. Compared with PBS treatment, SIMT increased pellet number, stool wet weight, and stool water percentage; induced a fecal microbiota profile shift toward the microbial composition of the SIM graft; induced a systemic anti-inflammatory cytokines profile; and ameliorated depressive-like behaviors in recipients. LIMT, however, induced merely a slight alteration in fecal microbial composition and no significant influence on the other aspects. In sum, SIMT, rather than LIMT, affected defecation features, fecal microbial composition, cytokines profile, and depressive-like behaviors in healthy mice. This study reveals the different effects of SIMT and LIMT, providing an interesting clue for further researches involving gut microbial composition change.

From gut microbiota to host appetite: gut microbiota-derived metabolites as key regulators

Feelings of hunger and satiety are the key determinants for maintaining the life of humans and animals. Disturbed appetite control may disrupt the metabolic health of the host and cause various metabolic disorders. A variety of factors have been implicated in appetite control, including gut microbiota, which develop the intricate interactions to manipulate the metabolic requirements and hedonic feelings. Gut microbial metabolites and components act as appetite-related signaling molecules to regulate appetite-related hormone secretion and the immune system, or act directly on hypothalamic neurons. Herein, we summarize the effects of gut microbiota on host appetite and consider the potential molecular mechanisms. Furthermore, we propose that the manipulation of gut microbiota represents a clinical therapeutic potential for lessening the development and consequence of appetite-related disorders. Video abstract.

Gut microbiota alteration and modulation in psychiatric disorders: Current evidence on fecal microbiota transplantation

The micro-organisms residing within the gastrointestinal tract, namely gut microbiota, form a dynamic population proper of each individual, mostly composed by bacteria which co-evolved symbiotically with human species. The advances of culture-independent techniques allowed the understanding of the multiple functions of the gut microbiota in human physiology and disease, the latter often recognising a predisposing condition in an imbalanced intestinal microbial ecosystem (dysbiosis). A complex mutual interconnection between the central nervous system (CNS), the intestine and the gut microbiota, known as "microbiota-gut-brain axis", has been hypothesized to play a pivotal role in maintaining central and peripheral functions, as well as mental health. Thus, dysbiosis with specific microbiota imbalances seems to be strongly associated with the onset psychiatric disorders by altering neurodevelopment, enhancing neurodegeneration, affecting behaviour and mood. Fecal microbiota transplantation (FMT) consists of transferring the fecal matter from a donor into the gastrointestinal tract of a recipient, and it is used to quickly modulate the gut microbiota. This review focuses on the uses of FMT in psychiatric disorders. FMT has been used to induce dysbiosis and to study the disease development, or to heal dysbiosis-related mental disorders. Overall, FMT of impaired microbiota resulted effective in enhancing psychiatric-like disturbances (mainly depression and anxiety) in recipient animals, plausibly by impairing immune system, inflammatory and metabolic pathways, neurochemical processes and neuro-transmission. On the other side, preclinical and clinical data suggest that reversing or mitigating dysbiosis seems a promising strategy to restore behavioural impairments or to obtain psychiatric symptom relief. However, current evidence is limited by the lack of procedural standardization, the paucity of human studies in the vastity of psychiatric conditions and the need of a microbiota-targeted donor-recipient matching.

Fecal microbiota transplantation in human metabolic diseases: From a murky past to a bright future?

Fecal microbiota transplantation (FMT) is gaining considerable traction as a therapeutic approach to influence the course of a plethora of chronic conditions, ranging from metabolic syndrome and malignancies to auto-immune and neurological diseases, and helped to establish the contribution of the gut microbiome to these conditions. Although FMT procedures have yielded important mechanistic insights, their use in clinical practice may be limited due to practical objections in the setting of metabolic diseases. While its applicability is established to treat recurrent Clostridiodes difficile, FMT is emerging in ulcerative colitis and various other diseases. A particularly new insight is that FMTs may not only alter insulin sensitivity but may also alter the course of type 1 diabetes by attenuating underlying auto-immunity. In this review, we will outline the major principles and pitfalls of FMT and where optimization of study design and the procedure itself will further advance the field of cardiometabolic medicine.

The role of the intestinal microbiota in eating disorders - bulimia nervosa and binge eating disorder

Bulimia nervosa (BN) and binge eating disorder (BED) are both eating disorders (EDs) characterised by episodes of overeating in which large amounts of food are consumed in short periods. The aetiology of BN and BED is not fully understood. Psychological and social factors influence the development of BN and BED, but biological factors such as neurohormones that regulate hunger and satiety, or neurotransmitters responsible for mood and anxiety play a significant role in sustaining symptoms. Increasing numbers of studies confirm the relationship between the composition of intestinal microbiota and the regulation of appetite, mood, and body mass. In this manuscript, we will describe the mechanisms by which intestinal dysbiosis can play an important role in the aetiology of binge eating episodes based on current understanding. Understanding the two-way relationship between BN and BED and alterations in the intestinal microbiota suggest the utility of new treatment methods of these disorders aimed at improving the composition of the intestinal microflora.

Faecal microbiota transplantation in endocrine diseases and obesity

The prevalence of type 1 (T1D) and type 2 diabetes mellitus (T2D) has greatly increased worldwide over the last century. Although the exact pathophysiology of both these conditions is distinct and still largely unknown, T1D as well as T2D, have been linked to distinct perturbations of the gut microbiome. Faecal microbiota transplantation (FMT) is a potent, and if performed well, a safe method to modulate the composition of the gut microbiome and thus positively influences the course of these hyperglycaemic conditions in humans. In this review, we provide an overview of how FMT is commonly performed and summarise how this procedure may reduce the insulin-resistance driving T2D, and the underlying auto-immunity driving T1D. Insights derived from FMT studies in T1D and T2D may help identify beneficial microbiota and associated metabolites that may serve as future treatments for these conditions.

Fecal Microbiota Transplantation from Overweight or Obese Donors in Cachectic Patients with Advanced Gastroesophageal Cancer: A Randomized, Double-blind, Placebo-Controlled, Phase II Study

PURPOSE

Cachexia is a multifactorial syndrome, associated with poor survival in patients with cancer, and is influenced by the gut microbiota. We investigated the effects of fecal microbiota transplantation (FMT) on cachexia and treatment response in patients with advanced gastroesophageal cancer.

EXPERIMENTAL DESIGN

In a double-blind randomized placebo-controlled trial performed in the Amsterdam University Medical Center, we assigned 24 cachectic patients with metastatic HER2-negative gastroesophageal cancer to either allogenic FMT (healthy obese donor) or autologous FMT, prior to palliative chemotherapy (capecitabine and oxaliplatin). Primary objective was to assess the effect of allogenic FMT on satiety. Secondary outcomes were other features of cachexia, along with disease control rate (DCR), overall survival (OS), progression-free survival (PFS), and toxicity. Finally, exploratory analyses were performed on the effect of FMT on gut microbiota composition (metagenomic sequencing) and metabolites (untargeted metabolomics).

RESULTS

Allogenic FMT did not improve any of the cachexia outcomes. Patients in the allogenic group (n = 12) had a higher DCR at 12 weeks (P = 0.035) compared with the autologous group (n = 12), longer median OS of 365 versus 227 days [HR = 0.38; 95% confidence interval (CI), 0.14-1.05; P = 0.057] and PFS of 204 versus 93 days (HR = 0.50; 95% CI, 0.21-1.20; P = 0.092). Patients in the allogenic group showed a significant shift in fecal microbiota composition after FMT (P = 0.010) indicating proper engraftment of the donor microbiota.

CONCLUSIONS

FMT from a healthy obese donor prior to first-line chemotherapy did not affect cachexia, but may have improved response and survival in patients with metastatic gastroesophageal cancer. These results provide a rational for larger FMT trials.

Gut microbiota depletion affects nutritional and behavioral responses to activity-based anorexia model in a sex-dependent manner

BACKGROUND & AIMS

In the last decade, the role of the microbiota-gut-brain axis in eating behavior and anxiety-depressive disorders has gained increasing attention. Although a gut microbiota dysbiosis has been reported in anorectic patients, its pathophysiological role remains poorly understood. Thus, we aimed to characterize the potential role of gut microbiota by evaluating the effects of its depletion in the Activity-Based Anorexia (ABA) mouse model both in male and female mice.

METHODS

Male and female C57Bl/6 mice were submitted (ABA group) or not (CT group) to the ABA protocol, which combines access to a running wheel with a progressive limited food access. Gut microbiota was previously depleted or not by a cocktail of antibiotics (ATB) delivered by oral gavages. We monitored body composition, anxiety-like behavior, leptin and adiponectin plasma levels, hypothalamic and hippocampal neuropeptides mRNA levels, as well as dopamine (DRD) and serotonin (5HT1 and 4) receptors mRNA expression.

RESULTS

In response to the ABA model, the body weight loss was less pronounced in ATB-treated ABA compared to untreated ABA, while food intake remained unaffected by ATB treatment. ATB-treated ABA exhibited increased fat mass and decreased lean mass compared to untreated ABA both in male and female mice, whereas but plasma adipokine concentrations were affected in a sex-dependent manner. Only male ABA mice showed a reduced anticipatory physical activity in response to ATB treatment. Similarly, anxiety-like behavior was mainly affected in ATB-treated ABA male mice compared to ATB-treated ABA female mice, which was associated with male-specific alterations of hypothalamic CRH mRNA and hippocampal DRD and 5-HT1A mRNA levels.

CONCLUSIONS

Our study provides evidence that ATB-induced gut microbiota depletion triggers alterations of nutritional and behavioral responses to the activity-based anorexia model in a sex-dependent manner.

Effects of Microbiota Imbalance in Anxiety and Eating Disorders: Probiotics as Novel Therapeutic Approaches

Anxiety and eating disorders produce a physiological imbalance that triggers alterations in the abundance and composition of gut microbiota. Moreover, the gut–brain axis can be altered by several factors such as diet, lifestyle, infections, and antibiotic treatment. Diet alterations generate gut dysbiosis, which affects immune system responses, inflammation mechanisms, the intestinal permeability, as well as the production of short chain fatty acids and neurotransmitters by gut microbiota, which are essential to the correct function of neurological processes. Recent studies indicated that patients with generalized anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific profile of gut microbiota, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation. Following the PRISMA methodology, the current review addresses the main microbial signatures observed in patients with generalized anxiety and/or eating disorders as well as the importance of probiotics as a preventive or a therapeutic tool in these pathologies.

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.

The Role of the Gut Microbiome, Immunity, and Neuroinflammation in the Pathophysiology of Eating Disorders

There is a growing recognition that both the gut microbiome and the immune system are involved in a number of psychiatric illnesses, including eating disorders. This should come as no surprise, given the important roles of diet composition, eating patterns, and daily caloric intake in modulating both biological systems. Here, we review the evidence that alterations in the gut microbiome and immune system may serve not only to maintain and exacerbate dysregulated eating behavior, characterized by caloric restriction in anorexia nervosa and binge eating in bulimia nervosa and binge eating disorder, but may also serve as biomarkers of increased risk for developing an eating disorder. We focus on studies examining gut dysbiosis, peripheral inflammation, and neuroinflammation in each of these eating disorders, and explore the available data from preclinical rodent models of anorexia and binge-like eating that may be useful in providing a better understanding of the biological mechanisms underlying eating disorders. Such knowledge is critical to developing novel, highly effective treatments for these often intractable and unremitting eating disorders.

Gut microbiota and brain alterations in a translational anorexia nervosa rat model

Anorexia nervosa (AN) is an eating disorder that leads to brain volume reduction and is difficult to treat since the underlying pathophysiology is poorly understood. The human gut microbiota is known to be involved in host metabolism, appetite- and bodyweight regulation, gut permeability, inflammation and gut-brain interactions. In this study, we used a translational activity-based anorexia (ABA) rat model including groups with food restriction, running-wheel access and a combination to disentangle the influences on the gut microbiota and associated changes in brain volume parameters. Our data demonstrated that chronic food restriction but not running-wheel activity had a major influence on the gut microbiota diversity and composition and reduced brain volume. Negative correlations were found between global brain weight and α-diversity, and astrocyte markers and relative abundances of the genera Odoribacter and Bifidobacterium. In contrast, the presence of lactobacilli was positively associated with white and grey brain matter volume. ABA and food-restricted rats are an interesting pre-clinical model to assess the causal influence of starvation on the gut microbiome and gut-brain interactions and can help to dissect the underlying pathophysiologic mechanisms relevant to AN.

Metabolism and Metabolic Disorders and the Microbiome: The Intestinal Microbiota Associated With Obesity, Lipid Metabolism, and Metabolic Health-Pathophysiology and Therapeutic Strategies

Changes in the intestinal microbiome have been associated with obesity and type 2 diabetes, in epidemiological studies and studies of the effects of fecal transfer in germ-free mice. We review the mechanisms by which alterations in the intestinal microbiome contribute to development of metabolic diseases, and recent advances, such as the effects of the microbiome on lipid metabolism. Strategies have been developed to modify the intestinal microbiome and reverse metabolic alterations, which might be used as therapies. We discuss approaches that have shown effects in mouse models of obesity and metabolic disorders, and how these might be translated to humans to improve metabolic health.

The role of faecal microbiota transplantation: looking beyond Clostridioides difficile infection

Faecal microbiota transplantation (FMT) is the transfer of screened and minimally processed faecal material from a 'healthy' donor to 'diseased' recipient. It has an established role, and is recommended as a therapeutic strategy, in the management of recurrent Clostridioides difficile infection (CDI). Recognition that gut dysbiosis is associated with, and may contribute to, numerous disease states has led to interest in exploiting FMT to 'correct' this microbial imbalance. Conditions for which it is proposed to be beneficial include inflammatory bowel disease, irritable bowel syndrome, liver disease and hepatic encephalopathy, neuropsychiatric conditions such as depression and anxiety, systemic inflammatory states like sepsis, and even coronavirus disease 2019. To understand what role, if any, FMT may play in the management of these conditions, it is important to consider the potential risks and benefits of the therapy. Regardless, there are several barriers to its more widespread adoption, which include incompletely understood mechanism of action (especially outside of CDI), inability to standardise treatment, disagreement on its active ingredients and how it should be regulated, and lack of long-term outcome and safety data. Whilst the transfer of faecal material from one individual to another to treat ailments or improve health has a history dating back thousands of years, there are fewer than 10 randomised controlled trials supporting its use. Moving forward, it will be imperative to gather as much data from FMT donors and recipients over as long a timeframe as possible, and for trials to be conducted with rigorous methodology, including appropriate control groups, in order to best understand the utility of FMT for indications beyond CDI. This review discusses the history of FMT, its appreciable mechanisms of action with reference to CDI, indications for FMT with an emerging evidence base above and beyond CDI, and future perspectives on the field.

A systematic review on the role of microbiota in the pathogenesis and treatment of eating disorders

Background

There is growing interest in new factors contributing to the genesis of eating disorders (EDs). Research recently focused on the study of microbiota. Dysbiosis, associated with a specific genetic susceptibility, may contribute to the development of anorexia nervosa (AN), bulimia nervosa, or binge eating disorder, and several putative mechanisms have already been identified. Diet seems to have an impact not only on modification of the gut microbiota, facilitating dysbiosis, but also on its recovery in patients with EDs.

Methods

This systematic review based on the PICO strategy searching into PubMed, EMBASE, PsychINFO, and Cochrane Library examined the literature on the role of altered microbiota in the pathogenesis and treatment of EDs.

Results

Sixteen studies were included, mostly regarding AN. Alpha diversity and short-chain fatty acid (SCFA) levels were lower in patients with AN, and affective symptoms and ED psychopathology seem related to changes in gut microbiota. Microbiota-derived proteins stimulated the autoimmune system, altering neuroendocrine control of mood and satiety in EDs. Microbial richness increased in AN after weight regain on fecal microbiota transplantation.

Conclusions

Microbiota homeostasis seems essential for a healthy communication network between gut and brain. Dysbiosis may promote intestinal inflammation, alter gut permeability, and trigger immune reactions in the hunger/satiety regulation center contributing to the pathophysiological development of EDs. A restored microbial balance may be a possible treatment target for EDs. A better and more in-depth characterization of gut microbiota and gut–brain crosstalk is required. Future studies may deepen the therapeutic and preventive role of microbiota in EDs.

Microbiome-based interventions: therapeutic strategies in cancer immunotherapy

The composition of the commensal microbiota has recently emerged as a key element influencing the efficacy of cancer treatments. It has become apparent that the interplay between the microbiome and immune system within the host influences the response to immunotherapy, particularly immune checkpoint inhibitor therapy. Identifying the key components of the gut microbiota that influence this response is paramount for designing therapeutic interventions to enhance the response to cancer therapy. This review will discuss strategies being considered to modulate the gut microbiota, including fecal microbiota transplantation, administration of defined bacterial isolates as well as bacterial consortia, supplementation with probiotics, and lifestyle modifications such as dietary changes. Understanding the influence of the complex variables of the human microbiota on the effectiveness of cancer therapy will help drive the clinical design of microbial-based interventions in the field of oncology.

Efficacy and safety of fecal microbiota transplantation for the treatment of diseases other than Clostridium difficile infection: a systematic review and meta-analysis

The intestinal microbiome has been identified as a key modifier for a variety of health conditions. Fecal Microbiota Transplantation (FMT) has emerged as a fast, safe, and effective means by which to modify the intestinal microbiome and potentially treat a variety of health conditions. Despite extensive research of FMT for CDI, there is a lack of clarity informed by systematic synthesis of data regarding the safety and efficacy of FMT for other health conditions. This systematic review used PRISMA guidelines and was prospectively registered with PROSPERO (CRD42018104243). In March 2020, a search of MEDLINE, EMBASE, and PsycINFO was conducted. We identified 26 eligible studies. A meta-analysis of FMT for active Ulcerative Colitis (UC) showed that FMT significantly improved rates of clinical remission (OR = 3.634, 95% CI = 1.940 to 6.808, I² = 0%, p < .001), clinical response (OR = 2.634, 95% CI = 1.441 to 4.815, I² = 33%, p = .002) and endoscopic remission (OR = 4.431, 95% CI = 1.901 to 10.324, I² = 0%, p = .001). With respect to Irritable Bowel Syndrome, a meta-analysis showed no significant change in symptoms following FMT (p = .739). Hepatic disorders, metabolic syndrome, and antibiotic-resistant organisms were conditions with emerging data on FMT. Serious adverse events (AE) were more often reported in control group participants (n = 43) compared with FMT group participants (n = 26). There were similar rates of mild to moderate AE in both groups. Preliminary data suggest that FMT is a potentially safe, well-tolerated and efficacious treatment for certain conditions other than CDI, with evidence for active UC being the most compelling.

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.

[Gut microbiome and anorexia nervosa : The relationship between microbiome and gut-brain interaction in the context of anorexia nervosa]

In recent years the intestinal microbiome and its interaction with the brain has aroused a growing interest. The findings gained in the course of this research are of great relevance not only to basic scientists but also to clinicians, as studies suggest an association between an altered microbiome and various somatic (e.g. chronic inflammatory intestinal diseases, obesity and diabetes) as well as psychiatric diseases (e.g. anxiety disorders, depression). In addition to a direct influence of the microbiome on the brain and behavior, various mechanisms seem to be relevant, including altered energy intake from food, hormonal changes, probably increased intestinal permeability as well as inflammatory and immunological processes. Anorexia nervosa (AN) is the third most common chronic disease in adolescence and has the highest mortality rate among all mental disorders. In addition to extremely restrictive eating habits, weight loss and comorbid anxiety and depression symptoms, endocrine changes and an increased autoimmune and inflammatory response are characteristic. Since AN is particularly strongly linked to eating behavior and nutrition, research into the microbiome seems very promising, especially with respect to this disease. This article gives a first insight into the underlying processes that play a role in gut-brain interaction in the context of AN and summarizes the previous empirical findings on this topic. Finally, an outlook on future research and possible implications for the therapeutic practice and treatment of AN is given.