The New Era of Treatment for Obesity and Metabolic Disorders: Evidence and Expectations for Gut Microbiome Transplantation

Modulation of the gut microbiome and Firmicutes phylum reduction by a nutraceutical blend in the obesity mouse model and overweight humans: A double-blind clinical trial

Overweight and obesity are closely linked to gut dysbiosis/dysmetabolism and disrupted De-Ritis ratio [aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio], which may contribute to chronic noncommunicable diseases onset. Concurrently, extensive research explores nutraceuticals, and health-enhancing supplements, for disease prevention or treatment. Thus, sedentary overweight volunteers were double-blind randomized into two groups: Novel Nutraceutical_(S) (without silymarin) and Novel Nutraceutical (with silymarin). Experimental formulations were orally administered twice daily over 180 consecutive days. We evaluated fecal gut microbiota, based on partial 16S rRNA sequences, biochemistry and endocrine markers, steatosis biomarker (AST/ALT ratio), and anthropometric parameters. Post-supplementation, only the Novel Nutraceutical group reduced Clostridium clostridioforme (Firmicutes), Firmicutes/Bacteroidetes ratio (F/B ratio), and De-Ritis ratio, while elevating Bacteroides caccae and Bacteroides uniformis (Bacteroidetes) in Brazilian sedentary overweight volunteers after 180 days. In summary, the results presented here allow us to suggest the gut microbiota as the action mechanism of the Novel Nutraceutical promoting metabolic hepatic recovery in obesity/overweight non-drug interventions.

Different Strategies Targeting Gut Microbiota for the Management of Several Disorders: A Sustainable Approach

BACKGROUND

A potential limelight is flashed on the Gut Microbiota (GM) in the human body, which confers additional psychological as well as physiological attributes to health. Other than just occupying a wide portion of the gastrointestinal tract, it also plays numerous functions in the systems of the body. Gut Microbiota is largely responsible for a considerably vast array of conditions such as obesity, diabetes ,other metabolic disorders, and cardiovascular disorders. Strategies targeting the gut microbiota have been proposed as a promising approach for the management of these disorders.

OBJECTIVE

This review aims to summarize the different strategies targeting the gut microbiota for the management of several disorders and to highlight the importance of a sustainable approach.

METHODS

A comprehensive literature search was conducted using various databases between 2008 and 2022 that focused on the use of prebiotics, probiotics, synbiotics, postbiotics, fecal microbiota transplantation, dietary interventions, and antibiotics.

RESULTS

Different strategies targeting the gut microbiota for the management of several disorders were identified, including probiotics, prebiotics, synbiotics, postbiotics, fecal microbiota transplantation, and dietary interventions. Modification in diet and lifestyle, allowing favorable microbiota growth in the stomach, intake of prebiotics and probiotics, and fecal microbiota transplantation are amongst the widely accepted recent approaches allowing the application of GM in the field of treatment.

CONCLUSION

Although considerable steps in enhancing and understanding the mechanism of treatment with the help of gut microbiota are under progress, much diversified and elaborate research must be conducted in order to enhance and implement the use of GM with high effectiveness.

Microbiome and intestinal pathophysiology in post-acute sequelae of COVID-19

Long COVID, also known for post-acute sequelae of COVID-19, describes the people who have the signs and symptoms that continue or develop after the acute COVID-19 phase. Long COVID patients suffer from an inflammation or host responses towards the virus approximately 4 weeks after initial infection with the SARS CoV-2 virus and continue for an uncharacterized duration. Anyone infected with COVID-19 before could experience long-COVID conditions, including the patients who were infected with SARS CoV-2 virus confirmed by tests and those who never knew they had an infection early. People with long COVID may experience health problems from different types and combinations of symptoms over time, such as fatigue, dyspnea, cognitive impairments, and gastrointestinal (GI) symptoms (e.g., nausea, vomiting, diarrhea, decreased or loss of appetite, abdominal pain, and dysgeusia). The critical role of the microbiome in these GI symptoms and long COVID were reported in clinical patients and experimental models. Here, we provide an overall view of the critical role of the GI tract and microbiome in the development of long COVID, including the clinical GI symptoms in patients, dysbiosis, viral-microbiome interactions, barrier function, and inflammatory bowel disease patients with long COVID. We highlight the potential mechanisms and possible treatment based on GI health and microbiome. Finally, we discuss challenges and future direction in the long COVID clinic and research.

Obesity and Its Multiple Clinical Implications between Inflammatory States and Gut Microbiotic Alterations

Obesity is a chronic multifactorial disease that has become a serious health problem and is currently widespread over the world. It is, in fact, strongly associated with many other conditions, including insulin resistance, type 2 diabetes, cardiovascular and neurodegenerative diseases, the onset of different types of malignant tumors and alterations in reproductive function. According to the literature, obesity is characterized by a state of low-grade chronic inflammation, with a substantial increase in immune cells, specifically macrophage infiltrates in the adipose tissue which, in turn, secrete a succession of pro-inflammatory mediators. Furthermore, recent studies on microbiota have postulated new possible mechanisms of interaction between obesity and unbalanced nutrition with inflammation. This intestinal "superorganism" complex seems to influence not only the metabolic balance of the host but also the immune response, favoring a state of systemic inflammation and insulin resistance. This review summarizes the major evidence on the interactions between the gut microbiota, energetic metabolism and host immune system, all leading to a convergence of the fields of immunology, nutrients physiology and microbiota in the context of obesity and its possible clinical complications. Finally, possible therapeutic approaches aiming to rebalance the intestinal microbial ecosystem are evaluated to improve the alteration of inflammatory and metabolic states in obesity and related diseases.

Vitamin D and ω-3 Polyunsaturated Fatty Acids towards a Personalized Nutrition of Youth Diabetes: A Narrative Lecture

After the discovery of insulin, nutrition has become central in the management of diabetes in order to limit glycemic rise after meals, optimize metabolic control, and prevent complications. Over the past one hundred years, international scientific societies have consecutively refined nutritional needs and optimized food intake for the treatment of diabetes. In particular, over the past century, nutrition applied with pumps for the administration of insulin and continuous glucose monitoring have allowed substantial advancement in the treatment of type 1 diabetes mellitus. The role of some substances, such as vitamin D and n-3 polyunsaturated fatty acids, have been proposed without univocal conclusions, individually or in combination, or in the diet, to improve the nutrition of type 1 and type 2 diabetes. This second condition, which is highly associated with overweight, should be prevented from childhood onwards. Personalized nutrition could bypass the problem, reaching a scientific conclusion on the individual subject. This article focuses on childhood and adolescent diabetes, aims to provide a narrative summary of nutrition over the past century, and promotes the concept of personalized nutrition to pediatricians and pediatric diabetologists as a possible tool for the treatment of type 1 diabetes and the prevention of type 2 diabetes.

Fecal Microbiota Transplantation as New Therapeutic Avenue for Human Diseases

The human body is home to a variety of micro-organisms. Most of these microbial communities reside in the gut and are referred to as gut microbiota. Over the last decades, compelling evidence showed that a number of human pathologies are associated with microbiota dysbiosis, thereby suggesting that the reinstatement of physiological microflora balance and composition might ameliorate the clinical symptoms. Among possible microbiota-targeted interventions, pre/pro-biotics supplementations were shown to provide effective results, but the main limitation remains in the limited microbial species available as probiotics. Differently, fecal microbiota transplantation involves the transplantation of a solution of fecal matter from a donor into the intestinal tract of a recipient in order to directly change the recipient's gut microbial composition aiming to confer a health benefit. Firstly used in the 4th century in traditional Chinese medicine, nowadays, it has been exploited so far to treat recurrent Clostridioides difficile infections, but accumulating data coming from a number of clinical trials clearly indicate that fecal microbiota transplantation may also carry the therapeutic potential for a number of other conditions ranging from gastrointestinal to liver diseases, from cancer to inflammatory, infectious, autoimmune diseases and brain disorders, obesity, and metabolic syndrome. In this review, we will summarize the commonly used preparation and delivery methods, comprehensively review the evidence obtained in clinical trials in different human conditions and discuss the variability in the results and the pivotal importance of donor selection. The final aim is to stimulate discussion and open new therapeutic perspectives among experts in the use of fecal microbiota transplantation not only in Clostridioides difficile infection but as one of the first strategies to be used to ameliorate a number of human conditions.

The potential application of probiotics for the prevention and treatment of COVID-19

Background

Given the severe infection, poor prognosis, and the low number of available effective drugs, potential prevention and treatment strategies for COVID-19 need to be urgently developed.

Main body

Herein, we present and discuss the possible protective and therapeutic mechanisms of human microbiota and probiotics based on the previous and recent findings. Microbiota and probiotics consist of mixed cultures of living microorganisms that can positively affect human health through their antiviral, antibacterial, anti-inflammatory, and immunomodulatory effect. In the current study, we address the promising advantages of microbiota and probiotics in decreasing the risk of COVID-19.

Conclusions

Thus, we recommend further studies be conducted for assessing and evaluating the capability of these microbes in the battle against COVID-19.

A Final Frontier in Environment-Genome Interactions? Integrated, Multi-Omic Approaches to Predictions of Non-Communicable Disease Risk

Epidemiological and associative research from humans and animals identifies correlations between the environment and health impacts. The environment-health inter-relationship is effected through an individual's underlying genetic variation and mediated by mechanisms that include the changes to gene regulation that are associated with the diversity of phenotypes we exhibit. However, the causal relationships have yet to be established, in part because the associations are reduced to individual interactions and the combinatorial effects are rarely studied. This problem is exacerbated by the fact that our genomes are highly dynamic; they integrate information across multiple levels (from linear sequence, to structural organisation, to temporal variation) each of which is open to and responds to environmental influence. To unravel the complexities of the genomic basis of human disease, and in particular non-communicable diseases that are also influenced by the environment (e.g., obesity, type II diabetes, cancer, multiple sclerosis, some neurodegenerative diseases, inflammatory bowel disease, rheumatoid arthritis) it is imperative that we fully integrate multiple layers of genomic data. Here we review current progress in integrated genomic data analysis, and discuss cases where data integration would lead to significant advances in our ability to predict how the environment may impact on our health. We also outline limitations which should form the basis of future research questions. In so doing, this review will lay the foundations for future research into the impact of the environment on our health.

Microbiota-Gut-Brain Axis and Epilepsy: A Review on Mechanisms and Potential Therapeutics

The gut-brain axis refers to the bidirectional communication between the gut and brain, and regulates intestinal homeostasis and the central nervous system via neural networks and neuroendocrine, immune, and inflammatory pathways. The development of sequencing technology has evidenced the key regulatory role of the gut microbiota in several neurological disorders, including Parkinson's disease, Alzheimer's disease, and multiple sclerosis. Epilepsy is a complex disease with multiple risk factors that affect more than 50 million people worldwide; nearly 30% of patients with epilepsy cannot be controlled with drugs. Interestingly, patients with inflammatory bowel disease are more susceptible to epilepsy, and a ketogenic diet is an effective treatment for patients with intractable epilepsy. Based on these clinical facts, the role of the microbiome and the gut-brain axis in epilepsy cannot be ignored. In this review, we discuss the relationship between the gut microbiota and epilepsy, summarize the possible pathogenic mechanisms of epilepsy from the perspective of the microbiota gut-brain axis, and discuss novel therapies targeting the gut microbiota. A better understanding of the role of the microbiota in the gut-brain axis, especially the intestinal one, would help investigate the mechanism, diagnosis, prognosis evaluation, and treatment of intractable epilepsy.

Strain engraftment competition and functional augmentation in a multi-donor fecal microbiota transplantation trial for obesity

BACKGROUND

Donor selection is an important factor influencing the engraftment and efficacy of fecal microbiota transplantation (FMT) for complex conditions associated with microbial dysbiosis. However, the degree, variation, and stability of strain engraftment have not yet been assessed in the context of multiple donors.

METHODS

We conducted a double-blinded randomized control trial of FMT in 87 adolescents with obesity. Participants were randomized to receive multi-donor FMT (capsules containing the fecal microbiota of four sex-matched lean donors) or placebo (saline capsules). Following a bowel cleanse, participants ingested a total of 28 capsules over two consecutive days. Capsules from individual donors and participant stool samples collected at baseline, 6, 12, and 26 weeks post-treatment were analyzed by shotgun metagenomic sequencing allowing us to track bacterial strain engraftment and its functional implications on recipients' gut microbiomes.

RESULTS

Multi-donor FMT sustainably altered the structure and the function of the gut microbiome. In what was effectively a microbiome competition experiment, we discovered that two donor microbiomes (one female, one male) dominated strain engraftment and were characterized by high microbial diversity and a high Prevotella to Bacteroides (P/B) ratio. Engrafted strains led to enterotype-level shifts in community composition and provided genes that altered the metabolic potential of the community. Despite our attempts to standardize FMT dose and origin, FMT recipients varied widely in their engraftment of donor strains.

CONCLUSION

Our study provides evidence for the existence of FMT super-donors whose microbiomes are highly effective at engrafting in the recipient gut. Dominant engrafting male and female donor microbiomes harbored diverse microbial species and genes and were characterized by a high P/B ratio. Yet, the high variability of strain engraftment among FMT recipients suggests the host environment also plays a critical role in mediating FMT receptivity.

TRIAL REGISTRATION

The Gut Bugs trial was registered with the Australian New Zealand Clinical Trials Registry ( ACTRN12615001351505 ).

TRIAL PROTOCOL

The trial protocol is available at https://bmjopen.bmj.com/content/9/4/e026174 . Video Abstract.

The views of pregnant women in New Zealand on vaginal seeding: a mixed-methods study

Background

Vaginal seeding is the administration of maternal vaginal bacteria to babies following birth by caesarean section (CS), intended to mimic the microbial exposure that occurs during vaginal birth. Appropriate development of the infant gut microbiome assists early immune development and might help reduce the risk of certain health conditions later in life, such as obesity and asthma. We aimed to explore the views of pregnant women on this practice.

Methods

We conducted a sequential mixed-methods study on the views of pregnant women in New Zealand (NZ) on vaginal seeding. Phase one: brief semi-structured interviews with pregnant women participating in a clinical trial of vaginal seeding (n = 15); and phase two: online questionnaire of pregnant women throughout NZ (not in the trial) (n = 264). Reflexive thematic analysis was applied to interview and open-ended questionnaire data. Closed-ended questionnaire responses were analysed using descriptive statistics.

Results

Six themes were produced through analysis of the open-ended data: “seeding replicates a natural process”, “microbiome is in the media”, “seeding may have potential benefits”, “seeking validation by a maternity caregiver”, “seeding could help reduce CS guilt”, and “the unknowns of seeding”. The idea that vaginal seeding replicates a natural process was suggested by some as an explanation to help overcome any initial negative perceptions of it. Many considered vaginal seeding to have potential benefit for the gut microbiome, while comparatively fewer considered it to be potentially beneficial for specific conditions such as obesity. Just under 30% of questionnaire respondents (n = 78; 29.5%) had prior knowledge of vaginal seeding, while most (n = 133; 82.6%) had an initially positive or neutral reaction to it. Few respondents changed their initial views on the practice after reading provided evidence-based information (n = 60; 22.7%), but of those who did, most became more positive (n = 51; 86.4%).

Conclusions

Given its apparent acceptability, and if shown to be safe and effective for the prevention of early childhood obesity, vaginal seeding could be a non-stigmatising approach to prevention of this condition among children born by CS. Our findings also highlight the importance of lead maternity carers in NZ remaining current in their knowledge of vaginal seeding research.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-020-03500-y.

Fecal microbiota transplantation for COVID-19; a potential emerging treatment strategy

At the end of 2019, an emerging outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that first reported from Wuhan, China. The first manifestations of patients infected with SARS-CoV-2 was flu-like symptoms, while other type of manifestations, especially gastrointestinal manifestations were discovered recently. As of June 2020, there is no specific drug or treatment strategy for COVID-19, a disease caused by SARS-CoV-2, so different combination of antiviral drugs is currently being used. Gut microbiota mostly consists of four phyla, including Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. The interaction between gut microbiota and immune system through releasing some cytokines such as IL-1β, IL-2, IL-10, TNF-α, and IFN-γ that play roles in the severity of COVID-19. In this article, a new potential treatment for COVID-19 by fecal microbiota transplantation (FMT) is described. FMT revealed promising results in different diseases, especially recurrent clostridium difficile infection, and it might reduce length of hospital admission and severity of the disease by modification of gut microbiota composition.

Gallstone Disease, Obesity and the Firmicutes/Bacteroidetes Ratio as a Possible Biomarker of Gut Dysbiosis

Obesity is a major risk factor for developing gallstone disease (GSD). Previous studies have shown that obesity is associated with an elevated Firmicutes/Bacteroidetes ratio in the gut microbiota. These findings suggest that the development of GSD may be related to gut dysbiosis. This review presents and summarizes the recent findings of studies on the gut microbiota in patients with GSD. Most of the studies on the gut microbiota in patients with GSD have shown a significant increase in the phyla Firmicutes (Lactobacillaceae family, genera Clostridium, Ruminococcus, Veillonella, Blautia, Dorea, Anaerostipes, and Oscillospira), Actinobacteria (Bifidobacterium genus), Proteobacteria, Bacteroidetes (genera Bacteroides, Prevotella, and Fusobacterium) and a significant decrease in the phyla Bacteroidetes (family Muribaculaceae, and genera Bacteroides, Prevotella, Alistipes, Paludibacter, Barnesiella), Firmicutes (genera Faecalibacterium, Eubacterium, Lachnospira, and Roseburia), Actinobacteria (Bifidobacterium genus), and Proteobacteria (Desulfovibrio genus). The influence of GSD on microbial diversity is not clear. Some studies report that GSD reduces microbial diversity in the bile, whereas others suggest the increase in microbial diversity in the bile of patients with GSD. The phyla Proteobacteria (especially family Enterobacteriaceae) and Firmicutes (Enterococcus genus) are most commonly detected in the bile of patients with GSD. On the other hand, the composition of bile microbiota in patients with GSD shows considerable inter-individual variability. The impact of GSD on the Firmicutes/Bacteroidetes ratio is unclear and reports are contradictory. For this reason, it should be stated that the results of reviewed studies do not allow for drawing unequivocal conclusions regarding the relationship between GSD and the Firmicutes/Bacteroidetes ratio in the microbiota.

Beyond the pan-genome: current perspectives on the functional and practical outcomes of the distributed genome hypothesis

The principle of monoclonality with regard to bacterial infections was considered immutable prior to 30 years ago. This view, espoused by Koch for acute infections, has proven inadequate regarding chronic infections as persistence requires multiple forms of heterogeneity among the bacterial population. This understanding of bacterial plurality emerged from a synthesis of what-were-then novel technologies in molecular biology and imaging science. These technologies demonstrated that bacteria have complex life cycles, polymicrobial ecologies, and evolve in situ via the horizontal exchange of genic characters. Thus, there is an ongoing generation of diversity during infection that results in far more highly complex microbial communities than previously envisioned. This perspective is based on the fundamental tenet that the bacteria within an infecting population display genotypic diversity, including gene possession differences, which result from horizontal gene transfer mechanisms including transformation, conjugation, and transduction. This understanding is embodied in the concepts of the supragenome/pan-genome and the distributed genome hypothesis (DGH). These paradigms have fostered multiple researches in diverse areas of bacterial ecology including host-bacterial interactions covering the gamut of symbiotic relationships including mutualism, commensalism, and parasitism. With regard to the human host, within each of these symbiotic relationships all bacterial species possess attributes that contribute to colonization and persistence; those species/strains that are pathogenic also encode traits for invasion and metastases. Herein we provide an update on our understanding of bacterial plurality and discuss potential applications in diagnostics, therapeutics, and vaccinology based on perspectives provided by the DGH with regard to the evolution of pathogenicity.

Metabolic networks of the human gut microbiota

The human gut microbiota controls factors that relate to human metabolism with a reach far greater than originally expected. Microbial communities and human (or animal) hosts entertain reciprocal exchanges between various inputs that are largely controlled by the host via its genetic make-up, nutrition and lifestyle. The composition of these microbial communities is fundamental to supply metabolic capabilities beyond those encoded in the host genome, and contributes to hormone and cellular signalling that support the dynamic adaptation to changes in food availability, environment and organismal development. Poor functional exchange between the microbial communities and their human host is associated with dysbiosis, metabolic dysfunction and disease. This review examines the biology of the dynamic relationship between the reciprocal metabolic state of the microbiota-host entity in balance with its environment (i.e. in healthy states), the enzymatic and metabolic changes associated with its imbalance in three well-studied diseases states such as obesity, diabetes and atherosclerosis, and the effects of bariatric surgery and exercise.

Effects of Antibiotics upon the Gut Microbiome: A Review of the Literature

The human gastrointestinal tract carries a large number of microorganisms associated with complex metabolic processes and interactions. Although antibiotic treatment is crucial for combating infections, its negative effects on the intestinal microbiota and host immunity have been shown to be of the utmost importance. Multiple studies have recognized the adverse consequences of antibiotic use upon the gut microbiome in adults and neonates, causing dysbiosis of the microbiota. Repeated antibiotic treatments in clinical care or low-dosage intake from food could be contributing factors in this issue. Researchers in both human and animal studies have strived to explain this multifaceted relationship. The present review intends to elucidate the axis of the gastrointestinal microbiota and antibiotics resistance and to highlight the main aspects of the issue.

Microbiota Transplant in the Treatment of Obesity and Diabetes: Current and Future Perspectives

A wealth of evidence has revealed the critical role of the gut microbiota in health and disease. Many chronic diseases have been associated with gut microbiota imbalance in its composition, diversity and functional capacity. Several types of interventions have been shown to correct microbiota imbalance and restore the beneficial metabolic outcomes of a normal microbiota. Among them, fecal microbiota transplantation (FMT) is an emergent, promising technology employed to improve clinical outcomes of various pathological conditions through modifications in the gut microbiota composition. FMT has been used successfully as a treatment option in recurrent Clostridium difficile infection, a condition characterized by severe gut microbiota dysbiosis. However, the potential usage of FMT in other microbiota-associated conditions different from C. difficile such as metabolic syndrome or obesity that are also marked by gut dysbiosis is still under investigation. Furthermore, the contribution of the gut microbiota as a cause or consequence in metabolic disease is still largely debated. This review provides critical information on the methodological approaches of FMT and its technological innovation in clinical applications. This review sheds light on the current findings and gaps in our understanding of how FMT can be used as a future biotherapeutic to restore microbial homeostasis in amelioration of obesity and diabetes.

Gut Microbiota and Epilepsy: A Systematic Review on Their Relationship and Possible Therapeutics

Dysbiosis of gut microbiota may lead to a range of diseases including neurological disorders. Thus, it is hypothesized that regulation of the intestinal microbiota may prevent or treat epilepsy. The purpose of this systematic review is to evaluate the evidence investigating the relationship between gut microbiota and epilepsy and possible interventions. A systematic review of the literature was done on four databases (PubMed, Scopus, EMBASE, and Web of Science). Study selection was restricted to original research articles while following the PRISMA guidelines. Six studies were selected. These studies cohesively support the interaction between gut microbiota and epileptic seizures. Gut microbiota analysis identified increases in Firmicutes, Proteobacteria, Verrucomicrobia, and Fusobacteria with decreases in Bacteroidetes and Actinobacteria in epileptic patients. Ketogenic diet, probiotics, and fecal microbiota transplantation (FMT) improved the dysbiosis of the gut microbiota and seizure activity. However, the studies either had a small sample size, lack of subject variability, or short study or follow-up period, which may question their reliability. Nevertheless, these limited studies conclusively suggest that gut microbiota diversity and dysbiosis may be involved in the pathology of epilepsy. Future studies providing more reliable and in depth insight into the gut microbial community will spark promising alternative therapies to current epilepsy treatment.

Changes in gut microbial flora after Roux-en-Y gastric bypass and sleeve gastrectomy and their effects on post-operative weight loss

Bariatric surgery affects gut microbial flora due to the anatomical and physiological changes it causes in the gastrointestinal tract. Understanding the interaction between the gut flora, the type of bariatric surgery and weight loss may help improve bariatric surgery outcomes. This study was designed to compare the effects of Roux-en-Y Gastric Bypass (RYGB) and Sleeve Gastrectomy (SG) on two main phyla of the gut microbiota in humans and evaluate their potential effect on weight changes. Thirty morbidly obese patients were divided into two groups and underwent laparoscopic SG or laparoscopic RYGB. The patients' weight changes and fecal samples were evaluated at baseline and 6 months after the surgery. A microbial flora count was carried out of the phyla Bacteroidetes and Firmicutes and Bacteroides Fragilis. Changes in the abundance of the flora and their correlation with weight loss were analyzed. After 6 months, the patients with a history of RYGB showed a significant decrease in stool Bacteroidetes while the reduction in the SG group was insignificant. Firmicutes abundance was almost unchanged following SG and RYGB. There was no significant change in Bacteroides Fragilis abundance in either of the two groups, but a positive correlation was observed between Bacteroides Fragilis and weight loss after SG and RYGB. Bariatric surgery can affect gut microbiota. It can be concluded that these changes are dependent on many factors and may play a role in weight loss.

Maternal bacteria to correct abnormal gut microbiota in babies born by C-section

INTRODUCTION

There is evidence that caesarean section (CS) is associated with increased risk of childhood obesity, asthma, and coeliac disease. The gut microbiota of CS-born babies differs to those born vaginally, possibly due to reduced exposure to maternal vaginal bacteria during birth. Vaginal seeding is a currently unproven practice intended to reduce such differences, so that the gut microbiota of CS-born babies is similar to that of babies born vaginally. Our pilot study, which uses oral administration as a novel form of vaginal seeding, will assess the degree of maternal strain transfer and overall efficacy of the procedure for establishing normal gut microbiota development.

METHODS AND ANALYSIS

Protocol for a single-blinded, randomized, placebo-controlled pilot study of a previously untested method of vaginal seeding (oral administration) in 30 CS-born babies. A sample of maternal vaginal bacteria is obtained prior to CS, and mixed with 5 ml sterile water to obtain a supernatant. Healthy babies are randomized at 1:1 to receive active treatment (3 ml supernatant) or placebo (3 ml sterile water). A reference group of 15 non-randomized vaginal-born babies are also being recruited. Babies' stool samples will undergo whole metagenomic shotgun sequencing to identify potential differences in community structure between CS babies receiving active treatment compared to those receiving placebo at age 1 month (primary outcome). Secondary outcomes include differences in overall gut community between CS groups (24 hours, 3 months); similarity of CS-seeded and placebo gut profiles to vaginally-born babies (24 hours, 1 and 3 months); degree of maternal vaginal strain transfer in CS-born babies (24 hours, 1 and 3 months); anthropometry (1 and 3 months) and body composition (3 months).

ETHICS AND DISSEMINATION

Ethics approval by the Northern A Health and Disability Ethics Committee (18/NTA/49). Results will be published in peer-reviewed journals and presented at international conferences.

REGISTRATION

Australian New Zealand Clinical Trials Registry (ACTRN12618000339257).

Microbiome in Multiple Sclerosis; Where Are We, What We Know and Do Not Know

An increase of multiple sclerosis (MS) incidence has been reported during the last decade, and this may be connected to environmental factors. This review article aims to encapsulate the current advances targeting the study of the gut-brain axis, which mediates the communication between the central nervous system and the gut microbiome. Clinical data arising from many research studies, which have assessed the effects of administered disease-modifying treatments in MS patients to the gut microbiome, are also recapitulated.

Interaction between delivery mode and maternal age in predicting overweight and obesity in 1,123 Chinese preschool children

Background

Pediatric overweight/obesity has escalated to epidemic proportions worldwide. In this study, we aimed to assess the association of delivery mode and maternal age, both individually and interactively, with the risk of being overweight or obese among Chinese preschool children.

Methods

We cross-sectionally recruited 1,123 preschool children from five kindergartens in Beijing. Data were collected by a pre-validated self-developed questionnaire. Overweight and obesity are defined according to the World Health Organization (WHO), International Obesity Task Force (IOTF), and China criteria, respectively.

Results

Cesarean delivery was significantly associated with pediatric overweight/obesity under the WHO [adjusted odds ratio (aOR), 95% confidence interval (CI): 1.60, 1.12-2.29], IOTF (1.77, 1.23-2.53), and China (1.43, 1.06-1.94) criteria, respectively. Maternal age <28 years reached statistical significance under both WHO (1.69, 1.09-2.61) and IOTF (1.69, 1.09-2.61) criteria in predicting pediatric overweight/obesity. The interaction between cesarean delivery and maternal age <28 years was remarkably significant under the WHO (2.26, 1.10-4.67), IOTF (2.92, 1.43-5.96), and China (2.36, 1.24-4.50) criteria.

Conclusions

Our findings indicate that the interaction between cesarean delivery and maternal age <28 years can remarkably increase the risk of overweight/obesity among Chinese preschool children.

The role of the gut microbiome in opioid use

Although the gut and brain are separate organs, they communicate with each other via trillions of intestinal bacteria that collectively make up one's gut microbiome. Findings from both humans and animals support a critical role of gut microbes in regulating brain function, mood, and behavior. Gut bacteria influence neural circuits that are notably affected in addiction-related behaviors. These include circuits involved in stress, reward, and motivation, with substance use influencing gut microbial abnormalities, suggesting significant gut-brain interactions in drug addiction. Given the overwhelming rates of opioid overdose deaths driven by abuse and addiction, it is essential to characterize mechanisms mediating the abuse potential of opioids. We discuss in this review the role of gut microbiota in factors that influence opioid addiction, including incentive salience, reward, tolerance, withdrawal, stress, and compromised executive function. We present clinical and preclinical evidence supporting a bidirectional relationship between gut microbiota and opioid-related behaviors by highlighting the effects of opioid use on gut bacteria, and the effects of gut bacteria on behavioral responses to opioids. Further, we discuss possible mechanisms of this gut-brain communication influencing opioid use. By clarifying the relationship between the gut microbiome and opioid-related behaviors, we improve understanding on mechanisms mediating reward-, motivation-, and stress-related behaviors and disorders, which may contribute to the development of effective, targeted therapeutic interventions in opioid dependence and addiction.

You've got male: Sex and the microbiota-gut-brain axis across the lifespan

Sex is a critical factor in the diagnosis and development of a number of mental health disorders including autism, schizophrenia, depression, anxiety, Parkinson's disease, multiple sclerosis, anorexia nervosa and others; likely due to differences in sex steroid hormones and genetics. Recent evidence suggests that sex can also influence the complexity and diversity of microbes that we harbour in our gut; and reciprocally that our gut microbes can directly and indirectly influence sex steroid hormones and central gene activation. There is a growing emphasis on the role of gastrointestinal microbiota in the maintenance of mental health and their role in the pathogenesis of disease. In this review, we introduce mechanisms by which gastrointestinal microbiota are thought to mediate positive health benefits along the gut-brain axis, we report how they may be modulated by sex, the role they play in sex steroid hormone regulation, and their sex-specific effects in various disorders relating to mental health.

Acceptability of alginate enriched bread and its effect on fat digestion in humans

Lifestyle interventions and physical activity remain the cornerstone of obesity management, as pharmacological therapies (orlistat) are associated with gastrointestinal (GI) side effects. Combining orlistat with fibers can reduce side effects, improving compliance. Therefore, a fiber that inhibits lipase without side effects could help treat obesity.

The aims of the present work were to assess whether alginate enriched bread could inhibit fat digestion, and assess the acceptability of alginate bread and its effect on GI wellbeing.

A double-blind, randomised, controlled cross-over pilot study (NCT03350958) assessed the impact of an alginate bread meal on; lipid content in ileal effluent and circulating triacylglycerol levels. This was compared against the same meal with non-enriched (control) bread.

GI wellbeing and acceptability of alginate bread was compared to control bread through daily wellbeing questionnaires and food diaries (NCT03477981). Control bread followed by alginate bread were consumed for two weeks respectively.

Consumption of alginate bread reduced circulating triacylglycerol compared to control (2% reduction in AUC) and significantly increased lipid content in ileal effluent (3.8 g ± 1.6 after 210 min).

There were no significant changes to GI wellbeing when comparing alginate bread to control bread. A significant increase in the feeling of fullness occurred with alginate bread compared to baseline and the first week of control bread consumption.

This study showed that sustained consumption of alginate enriched bread does not alter GI wellbeing and can decrease lipolysis, increasing lipid leaving the small intestine.

Further studies are required to demonstrate that reduced fat digestion through the action of alginate can reduce fat mass or body weight.

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Alginate can be incorporated into a highly acceptable loaf at 4%.

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Sustained (two weeks) consumption of alginate bread did not affect GI wellbeing.

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Consumption of alginate bread decreases circulating triglyceride after the meal.

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Consumption of alginate bread increases lipid leaving the ileum after the meal.

In search of stool donors: a multicenter study of prior knowledge, perceptions, motivators, and deterrents among potential donors for fecal microbiota transplantation

Fecal microbiota transplantation (FMT) is a highly effective therapy for recurrent Clostridioides difficile infection. Stool donors are essential, but difficult to recruit and retain. We aimed to identify factors influencing willingness to donate stool. This multi-center study with a 32-item questionnaire targeted young adults and health care workers via social media and university email lists in Edmonton and Kingston, Canada; London and Nottingham, England; and Indianapolis and Boston, USA. Items included baseline demographics and FMT knowledge and perception. Investigated motivators and deterrents included economic compensation, screening process, time commitment, and stool donation logistics. Logistic regression and linear regression models estimated associations of study variables with self-assessed willingness to donate stool. 802 respondents completed our questionnaire: 387 (48.3%) age 21-30 years, 573 (71.4%) female, 323 (40%) health care workers. Country of residence, age and occupation were not associated with willingness to donate stool. Factors increasing willingness to donate were: already a blood donor (OR 1.64), male, altruism, economic benefit, knowledge of how FMT can help patients (OR 1.32), and positive attitudes towards FMT (OR 1.39). Factors decreasing willingness to donate were: stool collection unpleasant (OR 0.92), screening process invasive (OR 0.92), higher stool donation frequency, negative social perception of stool, and logistics of collection/transporting feces. We conclude that 1) blood donors and males are more willing to consider stool donation; 2) altruism, economic compensation, and positive feedback are motivators; and 3) screening process, high donation frequency, logistics of collection/transporting feces, lack of public awareness, and negative social perception are deterrents. Considering these variables could maximize donor recruitment and retention.

Fecal Microbiota Transplantation: An Update on Clinical Practice

Fecal microbiota transplantation (FMT) is an infusion in the colon, or the delivery through the upper gastrointestinal tract, of stool from a healthy donor to a recipient with a disease believed to be related to an unhealthy gut microbiome. FMT has been successfully used to treat recurrent Clostridium difficile infection (rCDI). The short-term success of FMT in rCDI has led to investigations of its application to other gastrointestinal disorders and extra-intestinal diseases with presumed gut dysbiosis. Despite the promising results of FMT in these conditions, several barriers remain, including determining the characteristics of a healthy microbiome, ensuring the safety of the recipient with respect to long-term outcomes, adequate monitoring of the recipient of fecal material, achieving high-quality control, and maintaining reasonable costs. For these reasons, establishing uniform protocols for stool preparation, finding the best modes of FMT administration, maintaining large databases of donors and recipients, and assuring that oral ingestion is equivalent to the more widely accepted colonoscopic infusion are issues that need to be addressed.

Changes of gut microbiota between different weight reduction programs

BACKGROUND

Gut microbiota may induce obesity, diabetes, and metabolic syndrome. Different weight reduction programs may induce different changes in gut microbiota.

OBJECTIVES

To assess the changes in gut microbiota between obese adults who participated in 2 different weight reduction programs, the dietary counseling (DC) group and sleeve gastrectomy (SG) group, for 3 months.

SETTING

A University Hospital.

METHODS

Ten obese participants from each group were matched according to sex, age, and body mass index. Gut microbiota compositions were determined by metagenomics using next-generation sequencing before and after treatment. Anthropometric indices, metabolic factors, and gut microbiota were compared between and within groups.

RESULTS

After 3 months of treatment, compared with subjects in DC group, subjects in SG group experienced a greater reduction in body weight, body mass index, body fat, waist and hip circumference, diastolic blood pressure, hemoglobin, insulin, insulin resistance, glutamate pyruvate transaminase, blood urine nitrogen, and glycated hemoglobin (HbA1C). A total of 8, 17, and 46 species experienced significant abundance changes in DC, in SG, and between the 2 groups, respectively. Diversity of the gut flora increased in SG and between the 2 groups after treatment. The weight change over the course of the weight loss program was further adjusted and only 4 species, including Peptoniphilus lacrimalis 315 B, Selenomonas 4 sp., Prevotella 2 sp., and Pseudobutyrivibrio sp., were found to be significantly different between the 2 weight loss programs. These 4 species may be the different gut microbiota change between internal and surgical weight reduction programs.

CONCLUSIONS

There are significant differences not only in anthropometric indices and metabolic factors but also in gut microbiota change between the 2 programs.

Gut microbiome approaches to treat obesity in humans

The rising worldwide prevalence of obesity has become a major concern having many implications for the public health and the economy. It is well known that many factors such as lifestyle, increased intake of foods high in fat and sugar and a host's genetic profile can lead to obesity. Besides these factors, recent studies have pointed to the gut microbiota composition as being responsible for the development of obesity. Since then, many efforts have been made to understand the link between the gut microbiota composition and obesity, as well as the role of food ingredients, such as pro- and prebiotics, in the modulation of the gut microbiota. Studies involving the gut microbiota composition of obese individuals are however still controversial, making it difficult to treat obesity. In this sense, this mini-review deals with obesity and the relationship with gut microbiota, summarising the principal findings on gut microbiome approaches for treating obesity in humans.

The Human Microbiota and Obesity: A Literature Systematic Review of In Vivo Models and Technical Approaches

Obesity is a noncommunicable disease that affects a considerable part of humanity. Recently, it has been recognized that gut microbiota constitutes a fundamental factor in the triggering and development of a large number of pathologies, among which obesity is one of the most related to the processes of dysbiosis. In this review, different animal model approaches, methodologies, and genome scale metabolic databases were revisited to study the gut microbiota and its relationship with metabolic disease. As a data source, PubMed for English-language published material from 1 January 2013, to 22 August 2018, were screened. Some previous studies were included if they were considered classics or highly relevant. Studies that included innovative technical approaches or different in vivo or in vitro models for the study of the relationship between gut microbiota and obesity were selected after a 16-different-keyword exhaustive search. A clear panorama of the current available options for the study of microbiota’s influence on obesity, both for animal model election and technical approaches, is presented to the researcher. All the knowledge generated from the study of the microbiota opens the possibility of considering fecal transplantation as a relevant therapeutic alternative for obesity and other metabolic disease treatment.

Paternal diet programs offspring health through sperm- and seminal plasma-specific pathways in mice

Parental health and diet at the time of conception determine the development and life-long disease risk of their offspring. While the association between poor maternal diet and offspring health is well established, the underlying mechanisms linking paternal diet with offspring health are poorly defined. Possible programming pathways include changes in testicular and sperm epigenetic regulation and status, seminal plasma composition, and maternal reproductive tract responses regulating early embryo development. In this study, we demonstrate that paternal low-protein diet induces sperm-DNA hypomethylation in conjunction with blunted female reproductive tract embryotrophic, immunological, and vascular remodeling responses. Furthermore, we identify sperm- and seminal plasma-specific programming effects of paternal diet with elevated offspring adiposity, metabolic dysfunction, and altered gut microbiota.

The association between poor paternal diet, perturbed embryonic development, and adult offspring ill health represents a new focus for the Developmental Origins of Health and Disease hypothesis. However, our understanding of the underlying mechanisms remains ill-defined. We have developed a mouse paternal low-protein diet (LPD) model to determine its impact on semen quality, maternal uterine physiology, and adult offspring health. We observed that sperm from LPD-fed male mice displayed global hypomethylation associated with reduced testicular expression of DNA methylation and folate-cycle regulators compared with normal protein diet (NPD) fed males. Furthermore, females mated with LPD males display blunted preimplantation uterine immunological, cell signaling, and vascular remodeling responses compared to controls. These data indicate paternal diet impacts on offspring health through both sperm genomic (epigenetic) and seminal plasma (maternal uterine environment) mechanisms. Extending our model, we defined sperm- and seminal plasma-specific effects on offspring health by combining artificial insemination with vasectomized male mating of dietary-manipulated males. All offspring derived from LPD sperm and/or seminal plasma became heavier with increased adiposity, glucose intolerance, perturbed hepatic gene expression symptomatic of nonalcoholic fatty liver disease, and altered gut bacterial profiles. These data provide insight into programming mechanisms linking poor paternal diet with semen quality and offspring health.

The Transplantation of ω3 PUFA-Altered Gut Microbiota of fat-1 Mice to Wild-Type Littermates Prevents Obesity and Associated Metabolic Disorders

Altering the gut microbiome may be beneficial to the host and recently arose as a promising strategy to manage obesity. Here, we investigated the relative contribution of ω3 polyunsaturated fatty acid (PUFA)-mediated alterations in the microbiota to metabolic parameter changes in mice. Four groups were compared: male fat-1 transgenic mice (with constitutive production of ω3 PUFAs) and male wild-type (WT) littermates fed an obesogenic (high fat/high sucrose [HFHS]) or a control diet. Unlike WT mice, HFHS-fed fat-1 mice were protected against obesity, glucose intolerance, and hepatic steatosis. Unlike WT mice, fat-1 mice maintained a normal barrier function, resulting in a significantly lower metabolic endotoxemia. The fat-1 mice displayed greater phylogenic diversity in the cecum, and fecal microbiota transplantation from fat-1 to WT mice was able to reverse weight gain and to normalize glucose tolerance and intestinal permeability. We concluded that the ω3 PUFA-mediated alteration of gut microbiota contributed to the prevention of metabolic syndrome in fat-1 mice. It occurred independently of changes in the PUFA content of host tissues and may represent a promising strategy to prevent metabolic disease and preserve a lean phenotype.

Fecal transplantation: digestive and extradigestive clinical applications

Background and aim

Fecal transplantation or fecal material transplantation (FMT) became a hot topic in gastroenterology in recent years. Therefore it is important to disseminate the up-to-date information on FMT. The aim of the paper is to review the knowledge on FMT and its clinical applications.

Methods

An extensive review of the literature was carried out. Titles from Pubmed were searched and analyzed. A narrative review has been written with emphasis on indications of FMT in different conditions.

Results

The guidelines recommend FMT in relapsing infection with Clostridium difficile. Several attempts to use FMT in other conditions have been analyzed. Attempts were recorded in other bowel disorders like IBD, IBS, chronic constipation and even colorectal cancer. The attempt to change the microbiota by FMT in diabetes and obesity represent challenges for the future.

Conclusions

Fecal transplantation represents an important therapeutic method, intensively investigated these years. Beside the indication for persistent and recurrent Clostridium difficile infection, several attempts were undertaken in other intestinal diseases and in metabolic conditions. The efficiency of these applications has to be demonstrated.

Microbiota in obesity: interactions with enteroendocrine, immune and central nervous systems

Western diets, with high consumption of simple sugars and saturated fats, contribute to the rise in the prevalence of obesity. It now seems clear that high-fat diets cause obesity, at least in part, by modifying the composition and function of the microorganisms that colonize in the gastrointestinal tract, the microbiota. The exact pathways by which intestinal microbiota contribute to obesity remain largely unknown. High-fat diet-induced alterations in intestinal microbiota have been suggested to increase energy extraction, intestinal permeability and systemic inflammation while decreasing the capability to generate obesity-suppressing short-chain fatty acids. Moreover, by increasing systemic inflammation, microglial activation and affecting vagal nerve activity, 'obese microbiota' indirectly influence hypothalamic gene expression and promote overeating. Because the potential of intestinal microbiota to induce obesity has been recognized, multiple ways to modify its composition and function are being investigated to provide novel preventive and therapeutic strategies against diet-induced obesity.

Neonatal intestinal dysbiosis in necrotizing enterocolitis

Necrotizing Enterocolitis (NEC) is one of the most devastating gastrointestinal diseases in neonates, particularly among preterm infants in whom surgical NEC is the leading cause of morbidity. NEC pathophysiology occurs in the hyper-reactive milieu of the premature gut after bacterial colonization. The resultant activation of the TLR4 pathway appears to be a strongly contributing factor. Advancements in metagenomics may yield new clarity to the relationship between the neonatal intestinal microbiome and the development of NEC. After a century without effective directed treatments, microbiome manipulation offers a promising therapeutic target for the prevention and treatment of this devastating disease.

Dietary Polysaccharides in the Amelioration of Gut Microbiome Dysbiosis and Metabolic Diseases

The prevalence of metabolic diseases including obesity, diabetes, cardiovascular diseases, hypertension and cancer has evolved into a global epidemic over the last century. The rate of these disorders is continuously rising due to the lack of effective preventative and therapeutic strategies. This warrants for the development of novel strategies that could help in the prevention, treatment and/ or better management of such disorders. Although the complex pathophysiology of these metabolic diseases is one of the major hurdles in the development of preventive and/or therapeutic strategies, there are some factors that are or can speculated to be more effective to target than others. Recently, gut microbiome has emerged as one of the major contributing factors in metabolic diseases, and developing positive modulators of gut microbiota is being considered to be of significant interest. Natural non-digestible polysaccharides from plants and food sources are considered potent modulators of gut microbiome that can feed certain beneficial microbes in the gut. This has led to an increased interest in the isolation of novel bioactive polysaccharides from different plants and food sources and their application as functional components to modulate the gut microbiome composition to improve host's health including metabolism. Therefore, polysaccharides, as prebiotics components, are being speculated to confer positive effects in managing metabolic diseases like obesity and diabetes. In this review article, we summarize some of the most common polysaccharides from plants and food that impact metabolic health and discuss why and how these could be helpful in preventing or ameliorating metabolic diseases such as obesity, type 2 diabetes, hypertension and dyslipidemia.

Learning to starve: impacts of food limitation beyond the stress period

Starvation is common among wild animal populations, and many individuals experience repeated bouts of starvation over the course of their lives. Although much information has been gained through laboratory studies of acute starvation, little is known about how starvation affects an animal once food is again available (i.e. during the refeeding and recovery phases). Many animals exhibit a curious phenomenon – some seem to ‘get better’ at starving following exposure to one or more starvation events – by this we mean that they exhibit potentially adaptive responses, including reduced rates of mass loss, reduced metabolic rates, and lower costs of digestion. During subsequent refeedings they may also exhibit improved digestive efficiency and more rapid mass gain. Importantly, these responses can last until the next starvation bout or even be inherited and expressed in the subsequent generation. Currently, however, little is known about the molecular regulation and physiological mechanisms underlying these changes. Here, we identify areas of research that can fill in the most pressing knowledge gaps. In particular, we highlight how recently refined techniques (e.g. stable isotope tracers, quantitative magnetic resonance and thermal measurement) as well as next-generation sequencing approaches (e.g. RNA-seq, proteomics and holobiome sequencing) can address specific starvation-focused questions. We also describe outstanding unknowns ripe for future research regarding the timing and severity of starvation, and concerning the persistence of these responses and their interactions with other ecological stressors.

Weighted gene co-expression network analysis of expression data of monozygotic twins identifies specific modules and hub genes related to BMI

Background

The therapeutic management of obesity is challenging, hence further elucidating the underlying mechanisms of obesity development and identifying new diagnostic biomarkers and therapeutic targets are urgent and necessary. Here, we performed differential gene expression analysis and weighted gene co-expression network analysis (WGCNA) to identify significant genes and specific modules related to BMI based on gene expression profile data of 7 discordant monozygotic twins.

Results

In the differential gene expression analysis, it appeared that 32 differentially expressed genes (DEGs) were with a trend of up-regulation in twins with higher BMI when compared to their siblings. Categories of positive regulation of nitric-oxide synthase biosynthetic process, positive regulation of NF-kappa B import into nucleus, and peroxidase activity were significantly enriched within GO database and NF-kappa B signaling pathway within KEGG database. DEGs of NAMPT, TLR9, PTGS2, HBD, and PCSK1N might be associated with obesity. In the WGCNA, among the total 20 distinct co-expression modules identified, coral1 module (68 genes) had the strongest positive correlation with BMI (r = 0.56, P = 0.04) and disease status (r = 0.56, P = 0.04). Categories of positive regulation of phospholipase activity, high-density lipoprotein particle clearance, chylomicron remnant clearance, reverse cholesterol transport, intermediate-density lipoprotein particle, chylomicron, low-density lipoprotein particle, very-low-density lipoprotein particle, voltage-gated potassium channel complex, cholesterol transporter activity, and neuropeptide hormone activity were significantly enriched within GO database for this module. And alcoholism and cell adhesion molecules pathways were significantly enriched within KEGG database. Several hub genes, such as GAL, ASB9, NPPB, TBX2, IL17C, APOE, ABCG4, and APOC2 were also identified. The module eigengene of saddlebrown module (212 genes) was also significantly correlated with BMI (r = 0.56, P = 0.04), and hub genes of KCNN1 and AQP10 were differentially expressed.

Conclusion

We identified significant genes and specific modules potentially related to BMI based on the gene expression profile data of monozygotic twins. The findings may help further elucidate the underlying mechanisms of obesity development and provide novel insights to research potential gene biomarkers and signaling pathways for obesity treatment. Further analysis and validation of the findings reported here are important and necessary when more sample size is acquired.

Electronic supplementary material

The online version of this article (10.1186/s12864-017-4257-6) contains supplementary material, which is available to authorized users.

Impact of dietary fat on gut microbiota and low-grade systemic inflammation: mechanisms and clinical implications on obesity

Dietary fat strongly affects human health by modulating gut microbiota composition and low-grade systemic inflammation. High-fat diets have been implicated in reduced gut microbiota richness, increased Firmicutes to Bacteroidetes ratio, and several changes at family, genus and species levels. Saturated (SFA), monounsaturated (MUFA), polyunsaturated (PUFA) and conjugated linolenic fatty acids share important pathways of immune system activation/inhibition with gut microbes, modulating obesogenic and proinflammatory profiles. Mechanisms that link dietary fat, gut microbiota and obesity are mediated by increased intestinal permeability, systemic endotoxemia, and the activity of the endocannabinoid system. Although the probiotic therapy could be a complementary strategy to improve gut microbiota composition, it did not show permanent effects to treat fat-induced dysbiosis. Based upon evidence to date, we believe that high-fat diets and SFA consumption should be avoided, and MUFA and omega-3 PUFA intake should be encouraged in order to regulate gut microbiota and inflammation, promoting body weight/fat control.

The Human Microbiome and the Missing Heritability Problem

The "missing heritability" problem states that genetic variants in Genome-Wide Association Studies (GWAS) cannot completely explain the heritability of complex traits. Traditionally, the heritability of a phenotype is measured through familial studies using twins, siblings and other close relatives, making assumptions on the genetic similarities between them. When this heritability is compared to the one obtained through GWAS for the same traits, a substantial gap between both measurements arise with genome wide studies reporting significantly smaller values. Several mechanisms for this "missing heritability" have been proposed, such as epigenetics, epistasis, and sequencing depth. However, none of them are able to fully account for this gap in heritability. In this paper we provide evidence that suggests that in order for the phenotypic heritability of human traits to be broadly understood and accounted for, the compositional and functional diversity of the human microbiome must be taken into account. This hypothesis is based on several observations: (A) The composition of the human microbiome is associated with many important traits, including obesity, cancer, and neurological disorders. (B) Our microbiome encodes a second genome with nearly a 100 times more genes than the human genome, and this second genome may act as a rich source of genetic variation and phenotypic plasticity. (C) Human genotypes interact with the composition and structure of our microbiome, but cannot by themselves explain microbial variation. (D) Microbial genetic composition can be strongly influenced by the host's behavior, its environment or by vertical and horizontal transmissions from other hosts. Therefore, genetic similarities assumed in familial studies may cause overestimations of heritability values. We also propose a method that allows the compositional and functional diversity of our microbiome to be incorporated to genome wide association studies.

Biochemical, Cellular, Physiological, and Pathological Consequences of Human Loss of N-Glycolylneuraminic Acid

About 2-3 million years ago, Alu-mediated deletion of a critical exon in the CMAH gene became fixed in the hominin lineage ancestral to humans, possibly through a stepwise process of selection by pathogen targeting of the CMAH product (the sialic acid Neu5Gc), followed by reproductive isolation through female anti-Neu5Gc antibodies. Loss of CMAH has occurred independently in some other lineages, but is functionally intact in Old World primates, including our closest relatives, the chimpanzee. Although the biophysical and biochemical ramifications of losing tens of millions of Neu5Gc hydroxy groups at most cell surfaces remains poorly understood, we do know that there are multiscale effects functionally relevant to both sides of the host-pathogen interface. Hominin CMAH loss might also contribute to understanding human evolution, at the time when our ancestors were starting to use stone tools, increasing their consumption of meat, and possibly hunting. Comparisons with chimpanzees within ethical and practical limitations have revealed some consequences of human CMAH loss, but more has been learned by using a mouse model with a human-like Cmah inactivation. For example, such mice can develop antibodies against Neu5Gc that could affect inflammatory processes like cancer progression in the face of Neu5Gc metabolic incorporation from red meats, display a hyper-reactive immune system, a human-like tendency for delayed wound healing, late-onset hearing loss, insulin resistance, susceptibility to muscular dystrophy pathologies, and increased sensitivity to multiple human-adapted pathogens involving sialic acids. Further studies in such mice could provide a model for other human-specific processes and pathologies involving sialic acid biology that have yet to be explored.

Host-related factors explaining interindividual variability of carotenoid bioavailability and tissue concentrations in humans

Carotenoid dietary intake and their endogenous levels have been associated with a decreased risk of several chronic diseases. There are indications that carotenoid bioavailability depends, in addition to the food matrix, on host factors. These include diseases (e.g. colitis), life-style habits (e.g. smoking), gender and age, as well as genetic variations including single nucleotide polymorphisms that govern carotenoid metabolism. These are expected to explain interindividual differences that contribute to carotenoid uptake, distribution, metabolism and excretion, and therefore possibly also their association with disease risk. For instance, digestion enzymes fostering micellization (PNLIP, CES), expression of uptake/efflux transporters (SR-BI, CD36, NPC1L1), cleavage enzymes (BCO1/2), intracellular transporters (FABP2), secretion into chylomicrons (APOB, MTTP), carotenoid metabolism in the blood and liver (LPL, APO C/E, LDLR), and distribution to target tissues such as adipose tissue or macula (GSTP1, StARD3) depend on the activity of these proteins. In addition, human microbiota, e.g. via altering bile-acid concentrations, may play a role in carotenoid bioavailability. In order to comprehend individual, variable responses to these compounds, an improved knowledge on intra-/interindividual factors determining carotenoid bioavailability, including tissue distribution, is required. Here, we highlight the current knowledge on factors that may explain such intra-/interindividual differences.

Incorporating food addiction into disordered eating: the disordered eating food addiction nutrition guide (DEFANG)

Although not formally recognized by the DSM-5, food addiction (FA) has been well described in the scientific literature. FA has emerged as a clinical entity that is recognized within the spectrum of disordered eating, particularly in patients with bulimia nervosa, binge-eating disorder and/or co-occurring addictive disorders and obesity. Integrating the concept of FA into the scope of disordered eating has been challenging for ED treatment professionals, since there is no well-accepted treatment model. The confusion surrounding the implications of FA, as well as the impact of the contemporary Westernized diet, may contribute to poor treatment outcomes. The purpose of this review is twofold. The first is to briefly explore the relationships between EDs and addictions, and the second is to propose a new model of conceptualizing and treating EDs that incorporates recent data on FA. Since treatment for EDs should vary based on individual assessment and diagnosis, the Disordered Eating Food Addiction Nutrition Guide (DEFANG) is presented as a tool for framing treatment goals and helping patients achieve sustainable recovery.