Understanding the Gut Microbiota in Inflammatory and Functional Gastrointestinal Diseases

Irritable Bowel Syndrome: A Hallmark of Psychological Distress in Women?

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by abdominal pain, bloating, and altered bowel habits. Women are disproportionately affected by IBS due to a complex interplay between genetic, environmental, and psychosocial factors, along with a crucial role of the gut-brain axis in modulating both bowel function and pain perception. Evidence suggests a strong association between psychological distress and IBS symptoms. Women with IBS report higher levels of psychological distress compared to men, and sex is a biological variable that shapes several aspects of the mechanisms, epidemiology, and clinical manifestations of IBS. This paper explores the bidirectional relationship between psychological factors and IBS with a focus on women. Stress, anxiety, depression, and childhood trauma contribute to IBS symptomatology, and societal and biological factors unique to women may exacerbate this condition. Strategies for integrated care approaches and gender-specific treatment strategies to improve patient outcomes and quality of life are needed.

Alteration of gut microbiota in Henoch-Schönlein purpura children with gastrointestinal involvement

BACKGROUND

The compositional and structural changes of gut microbiota were closely related to the status of Henoch-Schönlein purpura (HSP).

AIMS

To investigate if clinical indicators and gut microbiota differ between HSP patients with or without gastrointestinal (GI) involvement and to explore the alterations of fecal microbiota in HSP children with and without GI symptoms.

METHODS

A total of 22 children with HSP were enrolled in the study. Fecal microbiota composition was analyzed by 16S rRNA sequencing. Clinical indicators, fecal microbial diversity, and compositions were compared between the two groups.

RESULTS

Respectively, 9 patients with GI involvement (HSP-A) and 13 patients without GI involvement (HSP-N) were enrolled. Prealbumin (PA) and the ratio of immunoglobulin A (IgA) / complement (C)3 were significantly decreased in the HSP-A group and an elevated D-dimer was found in the HSP-N group. The relative abundances of Blautia, Lachnospira, and Haemophilus were significantly higher in the HSP-A group compared to HSP-N. Lower levels of unidentified Prevotellaceae, Parabacteroides, and Romboutsia were found in HSP-A patients. The linear discriminant analysis effect size (LEfSe) showed that the biomarkers for the HSP-A group included Blautia, Anaerostipes, Veillonella, Lachnospira, and Haemophilus. For the HSP-N group, unidentified Prevotellaceae, Intestinibacter, Romboutsia, and Akkermansia were the prominent biomarkers at the genus level. Additionally, the ratio of IgA/C3 exhibited a negative correlation with the genus Blautia. Meanwhile, PA showed negatively correlation with Veillonella.

CONCLUSIONS

These results provide a broader understanding for future microbial-based therapies to decrease the development of GI involvement and improve the clinical outcome of HSP in children.

Periodontal Inflammation and Dysbiosis Relate to Microbial Changes in the Gut

Periodontal disease (PerioD) is a chronic inflammatory disease of dysbiotic etiology. Animal models and few human data showed a relationship between oral bacteria and gut dysbiosis. However, the effect of periodontal inflammation and subgingival dysbiosis on the gut is unknown. We hypothesized that periodontal inflammation and its associated subgingival dysbiosis contribute to gut dysbiosis even in subjects free of known gut disorders. We evaluated and compared elderly subjects with Low and High periodontal inflammation (assessed by Periodontal Inflamed Surface Area (PISA)) for stool and subgingival derived bacteria (assayed by 16S rRNA sequencing). The associations between PISA/subgingival dysbiosis and gut dysbiosis and bacteria known to produce short-chain fatty acid (SCFA) were assessed. LEfSe analysis showed that, in Low PISA, species belonging to Lactobacillus, Roseburia, and Ruminococcus taxa and Lactobacillus zeae were enriched, while species belonging to Coprococcus, Clostridiales, and Atopobium were enriched in High PISA. Regression analyses showed that PISA associated with indicators of dysbiosis in the gut mainly reduced abundance of SCFA producing bacteria (Radj = -0.38, p = 0.03). Subgingival bacterial dysbiosis also associated with reduced levels of gut SCFA producing bacteria (Radj = -0.58, p = 0.002). These results suggest that periodontal inflammation and subgingival microbiota contribute to gut bacterial changes.

Exploring the complexities of poultry respiratory microbiota: colonization, composition, and impact on health

An accurate understanding of the ecology and complexity of the poultry respiratory microbiota is of utmost importance for elucidating the roles of commensal or pathogenic microorganisms in the respiratory tract, as well as their associations with health or disease outcomes in poultry. This comprehensive review delves into the intricate aspects of the poultry respiratory microbiota, focusing on its colonization patterns, composition, and impact on poultry health. Firstly, an updated overview of the current knowledge concerning the composition of the microbiota in the respiratory tract of poultry is provided, as well as the factors that influence the dynamics of community structure and diversity. Additionally, the significant role that the poultry respiratory microbiota plays in economically relevant respiratory pathobiologies that affect poultry is explored. In addition, the challenges encountered when studying the poultry respiratory microbiota are addressed, including the dynamic nature of microbial communities, site-specific variations, the need for standardized protocols, the appropriate sequencing technologies, and the limitations associated with sampling methodology. Furthermore, emerging evidence that suggests bidirectional communication between the gut and respiratory microbiota in poultry is described, where disturbances in one microbiota can impact the other. Understanding this intricate cross talk holds the potential to provide valuable insights for enhancing poultry health and disease control. It becomes evident that gaining a comprehensive understanding of the multifaceted roles of the poultry respiratory microbiota, as presented in this review, is crucial for optimizing poultry health management and improving overall outcomes in poultry production.

Brain-Gut Axis: Invasive and Noninvasive Vagus Nerve Stimulation, Limitations, and Potential Therapeutic Approaches

Inflammatory bowel disease (IBD) is a chronic relapsing condition with no known etiology and is characterized by disrupted gut homeostasis, chronic inflammation, and ulcerative lesions. Although current treatments can reduce disease activity, IBD frequently recurs once treatments are discontinued, indicating that treatments are ineffective in providing long-term remission. The lack of responsiveness and reluctance of some affected persons to take medications because of potential adverse effects has enhanced the need for novel therapeutic approaches. The vagus nerve (VN) is likely important in the pathogenesis of IBD, considering the decreased activity of the parasympathetic nervous system, especially the VN, and the impaired interaction between the enteric nervous system and central nervous system in patients with IBD. Vagus nerve stimulation (VNS) has demonstrated anti-inflammatory effects in various inflammatory disorders, including IBD, by inhibiting the production of inflammatory cytokines by immune cells. It has been suggested that stimulating the vagus nerve to induce its anti-inflammatory effects may be a potential therapeutic approach for IBD. Noninvasive techniques for VNS have been developed. Considering the importance of VN function in the brain-gut axis, VNS is a promising treatment option for IBD. This review discusses the potential therapeutic advantages and drawbacks of VNS, particularly the use of noninvasive transcutaneous auricular vagus nerve stimulation.

Children and Adolescents with Irritable Bowel Syndrome: Treatment and Management

BACKGROUND

Irritable bowel syndrome (IBS) is a disorder that causes stomach pain in children and adolescents. It may also impact one's quality of life. IBS is linked to gastrointestinal issues such as diarrhoea and constipation. Despite the identification of several potential pathophysiological pathways, the aetiology of IBS remained unknown.

OBJECTIVE

The aim of this paper is to discuss the diagnosis, pathogenesis, case studies and treatment of Irritable bowel syndrome in children and adolescents.

METHODS

This systematic review covered relevant papers from the previous ten years that were accessible in Science Direct, Elsevier, NCBI, and Web of Science related to the pathophysiology and function of pharmacological drugs such as antidepressants, antispasmodics, prokinetics, and antibiotics in children with irritable bowel syndrome.

RESULTS

Only a few prospective therapy techniques have been investigated in children, and even fewer of those have been demonstrated to be effective. This article presents case studies including 50-59 children, which demonstrate a favourable acceptable impact that is more effective than a placebo in terms of reducing symptoms and improving the overall quality of life in children who have irritable bowel syndrome. Furthermore, the majority of the pathophysiological explanations and treatment options discussed are based on adult studies. These major issues arose when treating paediatric IBS, and they must be addressed in order to properly treat children with IBS. Trials that focus on many combinations of pharmacological and non-pharmacological therapies seem to be more helpful.

DISCUSSION

In recent years, a number of systematic reviews have been conducted to evaluate the efficacy of medication treatments in children for IBS; however, the dependability of these systematic reviews needs to be further investigated owing to the various experimental designs and levels of evidence used. This article highlights paediatric therapy options, including pharmaceutical medications such as antidepressants, antispasmodics, prokinetics, and antibiotics. The goal is to alleviate IBS symptoms while also enhancing the quality of life for children with this illness.

The role of intestinal microecology in inflammatory bowel disease and colorectal cancer: A review

Intestinal microecology is a dominant and complex microecological system in human body. Generally, intestinal microecosystem consists of normal symbiotic flora and its living environment (including intestinal epithelial tissue and intestinal mucosal immune system). Commensal flora is the core component of microecology. Both structures of intestinal mucosa and functions of immune system are essential to maintain homeostasis of intestinal microecosystem. Under normal conditions, intestinal microorganisms and intestinal mucosa coordinate with each other to promote host immunity. When certain factors in the intestine are altered, such as disruption of the intestinal barrier causing dysbiosis of the intestinal flora, the immune system of the host intestinal mucosa makes a series of responses, which leads to the development of intestinal inflammation and promotes colorectal cancer. In this review, to further understand the relationship between intestinal microecology and intestinal diseases, we systematically elaborate the composition of the intestinal mucosal immune system, analyze the relationship between intestinal flora and mucosal immune system, and the role of intestinal flora on intestinal inflammatory diseases and colorectal cancer.

The interplay between oral microbiota, gut microbiota and systematic diseases

Over the past two decades, the importance of microbiota in health and disease has become evident. The human gut microbiota and oral microbiota are the largest and second-largest microbiome in the human body, respectively, and they are physically connected as the oral cavity is the beginning of the digestive system. Emerging and exciting evidence has shown complex and important connections between gut microbiota and oral microbiota. The interplay of the two microbiomes may contribute to the pathological processes of many diseases, including diabetes, rheumatoid arthritis, nonalcoholic fatty liver disease, inflammatory bowel disease, pancreatic cancer, colorectal cancer, and so on. In this review, we discuss possible routes and factors of oral microbiota to affect gut microbiota, and the contribution of this interplay between oral and gut microbiota to systemic diseases. Although most studies are association studies, recently, there have been increasing mechanistic investigations. This review aims to enhance the interest in the connection between oral and gut microbiota, and shows the tangible impact of this connection on human health.

Fecal microbiota transplantation in the treatment of irritable bowel syndrome: a single-center prospective study in Japan

Background

Fecal microbiota transplantation (FMT) is a potential treatment for irritable bowel syndrome (IBS), but its efficacy in Japanese IBS patients is unknown. This study aimed to evaluate the efficacy, side effects, and microbiome changes following FMT in Japanese IBS patients.

Methods

Seventeen Japanese patients with refractory IBS received FMT (4 donors) under colonoscopy. Responders were defined by an improvement in the IBS severity index (IBS-SI) of 50 points or more after 12 weeks. We evaluated the IBS-SI and Bristol Stool Form Scale (BSFS) and compared the diversity and microbiome before and 12 weeks after FMT. For the microbiome, we analyzed the V3–V4 region of the 16S rRNA gene.

Results

IBS-SI decreased an average of 115.58 points after 12 weeks, and 10 patients (58.8%) were considered responders. Eight patients with diarrhea (66.7%) and three patients with constipation (60.0%) showed improvement in the BSFS. Two patients complained of mild abdominal pain, but there were no cases with severe side-effects. α-diversity was increased only in the responder group (p = 0.017). Patients who closely paralleled the donor microbiome had a higher rate of IBS-SI improvement. The relative abundance of Neisseria and Akkermansia increased and Desulfovibrio and Delftia were decreased in the responder group after FMT.

Conclusions

Following FMT, about 60% of Japanese patients with IBS showed improvement in both the IBS-SI and BSFS, without severe side effects. Increased α-diversity and similarity to the donor microbiome after FMT may be associated with better treatment effects.

Trial registration: This study was registered in the University Hospital Medical Information Network Clinical Trial Registration (UMIN000026363). Registered 31 May 2017, https://rctportal.niph.go.jp/s/detail/um?trial_id=UMIN000026363. The study was registered prospectively.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02408-5.

Changes in intestinal barrier protein expression and intestinal flora in a rat model of visceral hypersensitivity

BACKGROUND

Destruction of the intestinal mucosal barrier and visceral hypersensitivity are main pathogenesis of irritable bowel syndrome (IBS). The study aimed to establish a rat model of visceral hypersensitivity and explore mechanisms involved the changes of the intestinal barrier protein expression and intestinal flora.

METHODS

A rat model of visceral hypersensitivity was established and evaluated using abdominal withdrawal reflex (AWR) scores, colonic paracellular permeability, and gastrointestinal motility. The expression of tight junction proteins, aquaporin proteins (AQPs), phosphorylated ERK, and proteinase-activated receptor-2 (PAR-2) was determined. The intestinal microflora was evaluated by high-throughput sequencing of the 16S rRNA gene.

KEY RESULTS

In model rats, AWR score and fecal water content were significantly increased, gastrointestinal motilities were disorder and characterized by an inhibition of gastric motility and an enhancement of small intestinal and colonic movement. The expressions of colonic occludin, ZO-1, AQP3, and AQP8 were decreased but claudin-2 and claudin-4 were markedly increased. Imbalance of intestinal flora appeared and showed an obvious decrease of Lactobacillus and an increase of Clostridiales_bacterium. Additionally, the total serine protease activity in feces, the expressions of PAR2 and phosphorylated ERK in the colon tissues were increased significantly.

CONCLUSION AND INFERENCES

The model rats of visceral hypersensitivity possess the decreased expression of occludin, ZO-1, AQP3, AQP8, and the increased expression of claudin-2 and claudin-4, meanwhile develop an imbalance of intestinal flora which probably increase serine protease activity, thereby activating the PAR2/ERK signaling and causing the intestinal barrier disorder.

Antibiotic use but not gastrointestinal infection frequently precedes first diagnosis of functional gastrointestinal disorders

INTRODUCTION

While the etiopathogenesis of functional gastrointestinal disorders (FGIDs) is not completely understood, alterations of the intestinal microbiome have been observed. Antibiotics can induce dysbiosis, but whether antibiotics are a risk factor for the onset of FGIDs is uncertain. Antibiotics have been reported as both a risk factor for new onset FGID but also as a therapy for existing FGID. This study aimed to estimate the fraction of cases where antibiotics provoked the onset of FGID.

METHOD

Electronic medical records were obtained from general practices (primary care) in the United Kingdom. Dates of antibiotic prescription (AP) were compared with first date of FGID diagnosis and contrasted across three prevalent FGIDs and controls without gastrointestinal disorders.

RESULTS

There were 10,926 GI healthy controls, 4326 IBS alone, 3477 FD alone, 340 chronic constipation and 4402 with overlap of multiple conditions. Both the prevalence of AP and rate were higher in FGID patients and increased with diagnosis of multiple FGIDs. 7%-14% of FGID patients were prescribed their first recorded antibiotic in the 12 months prior to their first FGID diagnosis and 20%-33% were prescribed an antibiotic in the same period. Differences between FGID groups were not accounted for by social deprivation and only rate of AP was moderated by social deprivation. In contrast, only 5%-10% of patients ever had a gastrointestinal infection recorded and only 1.5%-3.5% prior to their first FGID diagnosis.

CONCLUSION

These data indicate that antibiotics are prescribed prior to FGID diagnosis in a significant minority of care-seeking FGID patients, opening the potential for this medication to contribute to the pathophysiology. APs appears to mostly be for non-gastrointestinal conditions.

Involvement of Probiotics and Postbiotics in the Immune System Modulation

Intestinal microbiota interacts with other systems, especially the immune system, which is responsible for protecting the body by recognizing “stranger” (pathogen associated molecular patterns-PAMPs) and “danger” (damage-associated molecular patterns-DAMPs) molecular motifs. In this manner, it plays an important role in the pathogenesis of various diseases and health. Despite the use of probiotics that modulate the intestinal microbiota in providing health benefits and in the treatment of diseases, there are some possible concerns about the possibility of developing adverse effects, especially in people with suppressed immune systems. Since probiotics provide health benefits with bioactive compounds, studies are carried out on the use of products containing non-living probiotic microorganisms (paraprobiotics) and/or their metabolites (postbiotics) instead of probiotic products. It is even reported that these microbial compounds have more immunomodulatory activities than living microorganisms via some possible mechanism and eliminates some disadvantages of probiotics. Considering the increasing use of functional foods in health and disease, further studies are needed with respect to the benefits and advantages of parabiotic and/or postbiotic use in the food and pharmaceutical industry as well as immune system modulation. Although probiotics have been extensive studied for a long time, it seems that postbiotics are promising tools for future research and applications according to the recent literature. This review aimed to evaluate the interaction of probiotics and postbiotics with the immune systems and also their advantages and disadvantages in the area of food-pharmaceutical industry and immune system modulation.

Therapeutic Potential of Vagus Nerve Stimulation for Inflammatory Bowel Diseases

The vagus nerve is a mixed nerve, comprising 80% afferent fibers and 20% efferent fibers. It allows a bidirectional communication between the central nervous system and the digestive tract. It has a dual anti-inflammatory properties via activation of the hypothalamic pituitary adrenal axis, by its afferents, but also through a vago-vagal inflammatory reflex involving an afferent (vagal) and an efferent (vagal) arm, called the cholinergic anti-inflammatory pathway. Indeed, the release of acetylcholine at the end of its efferent fibers is able to inhibit the release of tumor necrosis factor (TNF) alpha by macrophages via an interneuron of the enteric nervous system synapsing between the efferent vagal endings and the macrophages and releasing acetylcholine. The vagus nerve also synapses with the splenic sympathetic nerve to inhibit the release of TNF-alpha by splenic macrophages. It can also activate the spinal sympathetic system after central integration of its afferents. This anti-TNF-alpha effect of the vagus nerve can be used in the treatment of chronic inflammatory bowel diseases, represented by Crohn’s disease and ulcerative colitis where this cytokine plays a key role. Bioelectronic medicine, via vagus nerve stimulation, may have an interest in this non-drug therapeutic approach as an alternative to conventional anti-TNF-alpha drugs, which are not devoid of side effects feared by patients.

The alterations of tracheal microbiota and inflammation caused by different levels of ammonia exposure in broiler chickens

Ammonia (NH3) is a known harmful gas and exists in haze, forming secondary organic aerosols. Exposure to ambient ammonia correlates with the respiratory tract infection, and microbiota in the upper respiratory tract is an emerging crucial player in the homeostatic regulation of respiratory tract infection, and microbiota perturbation is usually accompanied by the inflammatory reactions; however, the effects of different levels of ammonia exposure on tracheal microbiota and inflammation are unclear. A total of 288 22-day-old male Arbor Acres broilers were chosen and divided into 4 groups with 6 replicates of 12 chickens, and respectively exposed to ammonia at 0, 15, 25, and 35 ppm for 21-d trial period. Cytokines (interleukin (IL)-1β, IL-6, and IL-10) in the trachea were measured at the 21 d of exposure to NH3. Tracheal microbiota at the 21 d was analyzed by the 16S rRNA gene analysis. The results showed that an increase in ammonia levels, even in 15 ppm, significantly decreased the alpha diversity and changed the bacterial community structure. Six genera (Faecalibacterium, Ruminococcus]_torques_group, unclassified_f__Lachnospiraceae, Ruminococcaceae_UCG-014, Streptococcus, Blautia) significantly increased, whereas Lactobacillus significantly decreased under different levels of ammonia exposure. We also observed positive associations of Faecalibacterium, Blautia, g__Ruminococcaceae_UCG-014, unclassified_f__Lachnospiraceae and Ruminococcus]_torques_group abundances with tracheal IL-1β concentration. Moreover, an increase in ammonia levels, even in 15 ppm, caused respiratory tract inflammatory injury. The results indicated that 15 ppm ammonia exposure changed the composition of tracheal microbiota that caused the tracheal injury possibly through increasing the IL-1β, which might make the broiler more sensitive to the changes of environment and pathogenic micro-organisms in the poultry house, and may be also a critical value that needs high alertness. Herein, the present experiment also suggested that the standard limit of ammonia concentration in adult poultry house is 15 ppm. This research provides an insight into the relationship between the upper respiratory tract microbiota and inflammation under ammonia exposure.

Parental, Perinatal, and Childhood Risk Factors for Development of Irritable Bowel Syndrome: A Systematic Review

Background/Aims

Adverse early life experiences are associated with the development of stroke, cancer, diabetes, and chronic respiratory and ischemic heart diseases. These negative experiences may also play a role in the development of irritable bowel syndrome (IBS)--a functional gastrointestinal disease. This review discusses the research to date on the parental, perinatal, and childhood risk and protective factors associated with the development of IBS.

Methods

A literature search was completed for studies published between 1966 and 2018 that investigated premorbid factors occurring during the perinatal and childhood periods as well as parental factors that were associated with the development of IBS.

Results

Twenty-seven studies fulfilled the review criteria. Risk factors that appeared in more than one study included: (1) parental IBS, substance abuse, parental punishment, and rejection as parental risk factors; (2) low birth weight as a perinatal risk factor; and (3) crowded living conditions in low-income families, childhood anxiety, depression, or child abuse as childhood risk factors. Protective factors for IBS were emotional warmth from the parents and being born to an older mother.

Conclusions

More effort is needed to identify what fetal and maternal factors are associated with low birth weight and IBS. A well-executed prospective birth cohort with a collection of bio-samples and functional data will provide a better understanding of how adversity and the interplay between genetics, epigenetics, and numerous risk factors affect the development of IBS.

Umbilicus acupuncture for treatment of diarrhea-type irritable bowel syndrome: Efficacy and impact on brain-gut peptides

BACKGROUND

Irritable bowel syndrome (IBS) is associated with brain-gut axis disorder. Umbilicus acupuncture has the effect of relieving cramps and treating diarrhea. We hypothesized that diarrhea-type irritable bowel syndrome (IBS-D) has a disorderd secretion of brain-gut peptides, and umbilicus acupuncture can improve the symptoms of IBS-D patients by regulating brain-gut peptide secretion.

AIM

To investigate the efficacy of umbilical acupuncture in patients with IBS-D and its effect on serum brain-gut peptides.

METHODS

Sixty patients who met the Rome IV diagnostic criteria for IBS-D were randomly divided into two groups in a single-blined manner: 30 patients who underwent umbilical acupuncture were included in an acupuncture group and 30 patients who were treated with bacillus licheniformin capsules were included in a probiotic group. The course of treatment was 4 weeks. Thirty healthy volunteers served as baseline controls. The changes of clinical symptom scores, SF-36 scale scores, Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) scores, serum brain-gut peptides [5-hydroxytryptamine(5-HT), calcitonin gene-related peptide (CGRP), substance P (SP), nitric oxide (NO), and vasoactive intestinal peptide (VIP)] after treatment were recorded. Adverse reactions were also recorded.

RESULTS

The clinical symptom scores after treatment in the two groups were significantly lower than those before treatment (P = 0.000). SF-36 scores of the two groups were significantly higher, while HAMD and HAMA scores were signficantly lower than those before treatment (P = 0.000). After treatment, the levels of 5-HT, CGRP, SP, NO, and VIP in the two groups decreased significantly (P < 0.0001). No adverse reactions occurred in either group.

CONCLUSION

Umbilical acupuncture can significantly improve the clinical symptoms and mental state of patients with IBS-D via mechanisms that may be related to regulating the secretion of 5-HT, CGRP, SP, NO, and VIP. Its therapeutic effect is equal to that of probiotics.

Prospects for the use of biomarkers in the diagnosis of irritable bowel syndrome

Irritable bowel syndrome is a chronic functional disorder of the intestine, manifested by altered intestinal habits and recurrent abdominal pain in combination with two or more criteria: association with defecation, association with a change in the frequency of defecation, association with a change in the appearance of the stool. To date, IBS remains a diagnosis of exclusion that needs to be differentiated from a wide range of organic diseases. In recent years, a large number of publications have appeared on the research of etiopathogenesis, diagnosis and treatment of IBS. This literary review highlights the problems of searching for biomarkers of IBS as a way to solve the problem of diagnosis of this pathology and understanding the causes of its occurrence.

Volatomics in inflammatory bowel disease and irritable bowel syndrome

Volatile organic compounds (VOCs) are produced by the human metabolism, inflammation and gut microbiota and form the basis of innovative volatomics research. VOCs detected through breath and faecal analysis hence serve as attractive, non-invasive biomarkers for diagnosing and monitoring irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). This review describes the clinical applicability of volatomics in discriminating between IBS, IBD and healthy volunteers with acceptable accuracy in breath (70%-100%) and faecal (58%-85%) samples. Promising compounds are propan-1-ol for diagnosing and monitoring of IBD patients, and 1-methyl-4-propan-2-ylcyclohexa-1,4-diene as biomarker for IBS diagnosis. However, these VOCs often seem to be related to inflammation and probably will need to be used in conjunction with other clinical evidence. Furthermore, three interventional studies underlined the potential of VOCs in predicting treatment outcome and patient follow-up. This shows great promise for future use of VOCs as non-invasive breath and faecal biomarkers in personalised medicine. However, properly designed studies that correlate VOCs to IBD/IBS pathogenesis, while taking microbial influences into account, are still key before clinical implementation can be expected.

The Evolving Role of Gut Microbiota in the Management of Irritable Bowel Syndrome: An Overview of the Current Knowledge

The intestinal microbiota is one of the most rapidly evolving areas in biology and medicine. Extensive research in the last decade has escalated our understanding of the role of the microbiota in the pathogenesis of several intestinal and extra-intestinal disorders. Marked by high prevalence, substantial morbidity, and enormous costs, irritable bowel syndrome (IBS) is an important chronic gastrointestinal disorder that is widely encountered by gastroenterologists. Despite advances in our understanding of its pathophysiology, curative interventions have yet to be discovered, and therapeutic approaches remain symptom-driven. Recently, accumulating evidence has enlightened the possible impact of an imbalanced gut microbiome in the pathogenesis of IBS. In fact, several studies have documented altered microbiota in patients, while others have shown that IBS severity was associated with a distinct microbiota signature. These findings may pave the way for the use of microbiota manipulation strategies as an attractive option for IBS management, and may have an essential role in efforts to reduce the societal and economic effects of this ever-growing disorder. In this review, we have outlined the results of the latest research on the association between microbiota and IBS and their implications for the clinical management of affected patients.

Oral Administration of Okara Soybean By-Product Attenuates Cognitive Impairment in a Mouse Model of Accelerated Aging

The microbiota-gut-brain axis has attracted increasing attention in the last decade. Here, we investigated whether okara, a soybean by-product rich in dietary fiber, can attenuate cognitive impairment in senescence-accelerated mouse prone 8 (SAMP8) mice by altering gut microbial composition. Mice were fed either a standard diet, or a diet containing okara (7.5% or 15%, w/w) for 26 weeks. In the memory test, the 7.5% okara-fed mice showed a longer step-through latency and the 15% okara-fed mice had a short escape latency compared with control mice. The 15% okara-fed mice displayed decreased body weight, increased fecal weight, and altered cecal microbiota composition compared with the control group; however, there was no significant difference in the serum lactic acid and butyric acid levels among these mice groups. The 7.5% okara-fed mice had significantly higher NeuN intensity in the hippocampus compared with control mice. Furthermore, a decrease in inflammatory cytokine TNF- and an increase in brain-derived neurotrophic factor (BDNF) was observed in the 7.5% okara-fed group. The expression of synthesizing enzyme of acetylcholine was increased by the okara diets, and the acetylcholine level in the brain was higher in the 7.5% okara-fed group than in the control. These suggest that oral administration of okara could delay cognitive decline without drastically changing gut microbiota.

Establishing What Constitutes a Healthy Human Gut Microbiome: State of the Science, Regulatory Considerations, and Future Directions

On December 17, 2018, the North American branch of the International Life Sciences Institute (ILSI North America) convened a workshop "Can We Begin to Define a Healthy Gut Microbiome Through Quantifiable Characteristics?" with >40 invited academic, government, and industry experts in Washington, DC. The workshop objectives were to 1) develop a collective expert assessment of the state of the evidence on the human gut microbiome and associated human health benefits, 2) see if there was sufficient evidence to establish measurable gut microbiome characteristics that could serve as indicators of "health," 3) identify short- and long-term research needs to fully characterize healthy gut microbiome-host relationships, and 4) publish the findings. Conclusions were as follows: 1) mechanistic links of specific changes in gut microbiome structure with function or markers of human health are not yet established; 2) it is not established if dysbiosis is a cause, consequence, or both of changes in human gut epithelial function and disease; 3) microbiome communities are highly individualized, show a high degree of interindividual variation to perturbation, and tend to be stable over years; 4) the complexity of microbiome-host interactions requires a comprehensive, multidisciplinary research agenda to elucidate relationships between gut microbiome and host health; 5) biomarkers and/or surrogate indicators of host function and pathogenic processes based on the microbiome need to be determined and validated, along with normal ranges, using approaches similar to those used to establish biomarkers and/or surrogate indicators based on host metabolic phenotypes; 6) future studies measuring responses to an exposure or intervention need to combine validated microbiome-related biomarkers and/or surrogate indicators with multiomics characterization of the microbiome; and 7) because static genetic sampling misses important short- and long-term microbiome-related dynamic changes to host health, future studies must be powered to account for inter- and intraindividual variation and should use repeated measures within individuals.

New insights into irritable bowel syndrome: from pathophysiology to treatment

Irritable bowel syndrome (IBS) is the most common reason to visit a gastroenterologist. IBS was believed to be a functional disease, but many possible pathophysiologic mechanisms can now explain the symptoms. IBS patients are classified into subtypes according to their predominant bowel habit, based on the Rome IV criteria. These include diarrhea-predominant and constipation-predominant IBS, as well as the mixed type, a combination of the two. Usually, IBS treatment is based on the predominant symptoms, with many options for each subtype. A new promising treatment option, fecal microbiota transplantation, seems to have beneficial effects on IBS. However, treating the pathophysiological causative agent responsible for the symptoms is an emerging approach. Therefore, before the appropriate therapeutic option is chosen for treating IBS, a clinical evaluation of its pathophysiology should be performed.

Gut Microbial Dysbiosis in the Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis of Case-Control Studies

BACKGROUND

Irritable bowel syndrome (IBS) is the most common functional digestive condition in the industrialized world. The gut microbiota plays a key role in disease pathogenesis.

OBJECTIVE

A systematic review and meta-analysis on case-control studies was conducted to determine whether there is gut microbial dysbiosis in participants with IBS in comparison with healthy controls and, if so, whether the dysbiosis pattern differs among IBS subtypes and geographic regions.

METHODS

This review was conducted and reported according to the MOOSE (Meta-Analysis of Observational Studies in Epidemiology) 2000 and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2009 guidelines. Research articles published up to May 9, 2018 were identified through MEDLINE (PubMed), Cochrane Central Register of Controlled Trials (Cochrane Library), ClinicalTrials.gov, EMBASE, and Web of Science. Study quality was assessed using the Newcastle-Ottawa Scale. Case-control studies of participants with IBS who had undergone quantitative gut microbial stool analysis were included. The primary exposure measure of interest is log₁₀ bacterial counts per gram of stool. Meta-analyses were performed to estimate the mean difference (MD) in gut microbiota between participants with IBS and healthy controls using the random-effects model with inverse variance in Revman 5.3 and R 3.5.1. Publication bias was assessed with funnel plots and Egger's test. Between-study heterogeneity was analyzed using Higgins I² statistic with 95% CIs.

RESULTS

There were 6,333 unique articles identified; 52 qualified for full-text screening. Of these, 23 studies were included for analysis (n=1,340 participants from North America, Europe, and Asia). Overall, the studies were moderate in quality. Comparing participants with IBS to healthy controls, lower fecal Lactobacillus (MD= -0.57 log₁₀ colony-forming unit [CFU]/g; P<0.01) and Bifidobacterium (MD= -1.04 log₁₀CFU/g; P<0.01), higher Escherichia coli (MD=0.60 log₁₀CFU/g; P<0.01), and marginally higher Enterobacter (MD=0.74 log₁₀CFU/g; P=0.05). No difference was found between participants with IBS and healthy controls in fecal Bacteroides and Enterococcus (P=0.18 and 0.68, respectively). Publication bias was not observed except in Bifidobacterium (P=0.015). Subgroup analyses on participants with diarrhea-predominant and constipation-predominant IBS showed consistent results with the primary results. A subgroup analysis of Chinese studies was consistent with the primary results, except for fecal Bacteroides, which was increased in participants with IBS vs healthy controls (MD=0.29; 95% CI 0.13 to 0.46; P<0.01). Although substantial heterogeneity was detected (I²>75%) in most comparisons, the direction of the effect estimates is relatively consistent across studies.

CONCLUSIONS

IBS is characterized by gut microbial dysbiosis. Prospective, large-scale studies are needed to delineate how gut microbial profiles can be used to guide targeted therapies in this challenging patient population.

Role of intestinal microbiota and metabolites in inflammatory bowel disease

OBJECTIVE

The metabolites produced by the gut microbiota are of interest to scientists. The objective of this review was to provide an updated summary of progress regarding the microbiota and their metabolites and influences on the pathogenesis of inflammatory bowel disease (IBD).

DATA SOURCES

The author retrieved information from the PubMed database up to January 2018, using various combinations of search terms, including IBD, microbiota, and metabolite.

STUDY SELECTION

Both clinical studies and animal studies of intestinal microbiota and metabolites in IBD were selected. The information explaining the possible pathogenesis of microbiota in IBD was organized.

RESULTS

In IBD patients, the biodiversity of feces/mucosa-associated microbiota is decreased, and the probiotic microbiota is also decreased, whereas the pathogenic microbiota are increased. The gut microbiota may be a target for diagnosis and treatment of IBD. Substantial amounts of data support the view that the microbiota and their metabolites play pivotal roles in IBD by affecting intestinal permeability and the immune response.

CONCLUSIONS

This review highlights the advances in recent gut microbiota research and clarifies the importance of the gut microbiota in IBD pathogenesis. Future research is needed to study the function of altered bacterial community compositions and the roles of metabolites.

Increasing the Dose and/or Repeating Faecal Microbiota Transplantation (FMT) Increases the Response in Patients with Irritable Bowel Syndrome (IBS)

BACKGROUND

Faecal microbiome transplantation (FMT) appears to be an effective method for treating irritable bowel syndrome (IBS) patients. However, it is not clear if a high transplant dose and/or repeating FMT are/is needed to ensure a response. The present study was undertaken to clarify this matter.

METHODS

Ten IBS patients who did not respond to a 30-g transplant subsequently received a 60-g transplant into the duodenum via a gastroscope. The patients provided faecal samples before and 1 month after FMT. They completed five questionnaires measuring symptoms, fatigue and quality of life at baseline and then at 2 weeks, 1 month and 3 months after FMT. The dysbiosis index (DI) was measured using the GA-map Dysbiosis Test®.

RESULTS

Seven patients (70%) responded to the 60-g transplant, with significant clinical improvements in the abdominal symptoms, fatigue and quality of life in 57%, 80% and 67% of these patients. The 60-g transplant also reduced the DI.

CONCLUSION

FMT is an effective treatment for IBS. A high-dose transplant and/or repeated FMT increase the response rate and the intensity of the effects of FMT.

AGA Clinical Practice Update on Functional Gastrointestinal Symptoms in Patients With Inflammatory Bowel Disease: Expert Review

DESCRIPTION

The purpose of this clinical practice update review is to describe key principles in the diagnosis and management of functional gastrointestinal (GI) symptoms in patients with inflammatory bowel disease (IBD).

METHODS

The evidence and best practices summarized in this manuscript are based on relevant scientific publications, systematic reviews, and expert opinion where applicable. Best practice advice 1: A stepwise approach to rule-out ongoing inflammatory activity should be followed in IBD patients with persistent GI symptoms (measurement of fecal calprotectin, endoscopy with biopsy, cross-sectional imaging). Best practice advice 2: In those patients with indeterminate fecal calprotectin levels and mild symptoms, clinicians may consider serial calprotectin monitoring to facilitate anticipatory management. Best practice advice 3: Anatomic abnormalities or structural complications should be considered in patients with obstructive symptoms including abdominal distention, pain, nausea and vomiting, obstipation or constipation. Best practice advice 4: Alternative pathophysiologic mechanisms should be considered and evaluated (small intestinal bacterial overgrowth, bile acid diarrhea, carbohydrate intolerance, chronic pancreatitis) based on predominant symptom patterns. Best practice advice 5: A low FODMAP diet may be offered for management of functional GI symptoms in IBD with careful attention to nutritional adequacy. Best practice advice 6: Psychological therapies (cognitive behavioural therapy, hypnotherapy, mindfulness therapy) should be considered in IBD patients with functional symptoms. Best practice advice 7: Osmotic and stimulant laxative should be offered to IBD patients with chronic constipation. Best practice advice 8: Hypomotility agents or bile-acid sequestrants may be used for chronic diarrhea in quiescent IBD. Best practice advice 9: Antispasmodics, neuropathic-directed agents, and anti-depressants should be used for functional pain in IBD while use of opiates should be avoided. Best practice advice 10: Probiotics may be considered for treatment of functional symptoms in IBD. Best practice advice 11: Pelvic floor therapy should be offered to IBD patients with evidence of an underlying defecatory disorder. Best practice advice 12: Until further evidence is available, fecal microbiota transplant should not be offered for treatment of functional GI symptoms in IBD. Best practice advice 13: Physical exercise should be encourage in IBD patients with functional GI symptoms. Best practice advice 14: Until further evidence is available, complementary and alternative therapies should not be routinely offered for functional symptoms in IBD. This Clinical Practice Update was produced by the AGA Institute.

Fecal microbiota profiles in treatment-naïve pediatric inflammatory bowel disease - associations with disease phenotype, treatment, and outcome

Purpose

Imbalance in the microbiota, dysbiosis, has been identified in inflammatory bowel disease (IBD). We explored the fecal microbiota in pediatric patients with treatment-naïve IBD, non-IBD patients with gastrointestinal symptoms and healthy children, its relation to IBD subgroups, and treatment outcomes.

Patients and methods

Fecal samples were collected from 235 children below 18 years of age. Eighty children had Crohn’s disease (CD), 27 ulcerative colitis (UC), 3 IBD unclassified, 50 were non-IBD symptomatic patients, and 75 were healthy. The bacterial abundance of 54 predefined DNA markers was measured with a 16S rRNA DNA-based test using GA-Map^™ technology at diagnosis and after therapy in IBD patients.

Results

Bacterial abundance was similarly reduced in IBD and non-IBD patients in 51 of 54 markers compared to healthy patients (P<0.001). Only Prevotella was more abundant in patients (P<0.01). IBD patients with ileocolitis or total colitis had more Ruminococcus gnavus (P=0.02) than patients with colonic CD or left-sided UC. CD patients with upper gastrointestinal manifestations had higher Veillonella abundance (P<0.01). IBD patients (58%) who received biologic therapy had lower baseline Firmicutes and Mycoplasma hominis abundance (P<0.01) than conventionally treated. High Proteobacteria abundance was associated with stricturing/penetrating CD, surgery (P<0.01), and nonmucosal healing (P<0.03). Low Faecalibacterium prausnitzii abundance was associated with prior antibiotic therapy (P=0.001), surgery (P=0.02), and nonmucosal healing (P<0.03). After therapy, IBD patients had unchanged dysbiosis.

Conclusion

Fecal microbiota profiles differentiated IBD and non-IBD symptomatic children from healthy children, but displayed similar dysbiosis in IBD and non-IBD symptomatic patients. Pretreatment fecal microbiota profiles may be of prognostic value and aid in treatment individualization in pediatric IBD as severe dysbiosis was associated with an extensive, complicated phenotype, biologic therapy, and nonmucosal healing. The dysbiosis persisted after therapy, regardless of treatments and mucosal healing.

Intestinal Microbiome in Irritable Bowel Syndrome before and after Gut-Directed Hypnotherapy

Irritable bowel syndrome (IBS) is a disorder with brain-gut-microbiome alterations. Gut-directed hypnotherapy (GHT) has been shown to improve quality of life and symptoms in IBS. This therapy targets psychological coping, central nervous processing and brain-gut interaction. Studies have also demonstrated effects of hypnosis on intestinal transit and the mucosal immune system. So far, no study has examined the effect of GHT on the intestinal microbiome. This study aimed at examining microbial composition, IBS symptoms, and psychological distress before and after GHT. Methods: Fecal samples were collected from 38 IBS patients (Rome-III criteria, mean age 44 years, 27 female, 11 male, 22 diarrhea-dominant, 12 alternating-type and 4 constipation-dominant IBS) before and after 10 weekly group sessions of GHT. Assessments in psychological (perceived stress, PSQ; psychological distress, HADS-D; quality of life, visual analogue scales) and IBS symptom-related variables (IBS severity, IBS-SSS; single symptoms, visual analogue scales) were performed with validated questionnaires. Fecal samples underwent microbial 16S rRNA analyses (regions V1–2). Results: Microbial alpha diversity was stable before and after GHT (chao1 2591 ± 548 vs. 2581 ± 539, p = 0.92). No significant differences were found in relative bacterial abundances but trends of reduced abundance of Lachnospiraceae 32.18 (4.14–39.89) Median (Q1–Q3) vs. 28.11 (22.85; 35.55) and Firmicutes: Bacteroidetes ratio after GHT were observable. Significant reductions in symptom severity (323 (266–371) vs. 264 (191–331), p = 0.001) and psychological distress 17.0 (12.6–21.8) vs. 12.0 (8.3–18.0), p = 0.001, and increased well-being were found after GHT. Adequate relief after therapy was reported by 32 (84%) patients. Conclusion: Reductions in IBS symptoms and psychological burden were observed after gut-directed hypnotherapy, but only small changes were found in intestinal microbiota composition. The findings suggest that hypnosis may act by central nervous impact and other factors largely independent from microbiota composition modulating the brain-gut axis, possibly alterations in vagus nerve functioning and microbiota metabolism.

A Microbial Signature of Psychological Distress in Irritable Bowel Syndrome

OBJECTIVE

Irritable bowel syndrome (IBS) is associated with alterations along the brain-gut-microbiota axis. Previous studies have suggested a parallel segregation of microbial features and psychological burden in IBS. This study aimed at exploring the microbial correlates of psychological distress in patients with IBS.

METHODS

Forty-eight patients with IBS (Rome III criteria, M (SD) age = 42 (15) years, 35 female, 25 diarrhea-dominant, 5 constipation-dominant, and 18 alternating-type IBS) were assessed for psychological and clinical variables with validated questionnaires, fecal samples underwent microbial 16S rRNA analyses (regions V1-2). Microbial analyses comprised examination of alpha and beta diversity, correlational analyses of bacterial abundance and comparisons among subgroups defined by thresholds of psychological and IBS symptom variables, and machine learning to identify bacterial patterns corresponding with psychological distress.

RESULTS

Thirty-one patients (65%) showed elevated psychological distress, 22 (31%) anxiety, and 10 depression (21%). Microbial beta diversity was significantly associated with distress and depression (q = .036 each, q values are p values false discovery rate-corrected for multiple testing). Depression was negatively associated with Lachnospiraceae abundance (Spearman's ρ = -0.58, q = .018). Patients exceeding thresholds of distress, anxiety, depression, and stress perception showed significantly higher abundances of Proteobacteria (q = .020-.036). Patients with anxiety were characterized by elevated Bacteroidaceae (q = .036). A signature of 148 unclassified species accounting for 3.9% of total bacterial abundance co-varied systematically with the presence of psychological distress.

CONCLUSIONS

Psychological variables significantly segregated gut microbial features, underscoring the role of brain-gut-microbiota interaction in IBS. A microbial signature corresponding with psychological distress was identified.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT02536131, retrospectively registered.

Fecal microbiota transplantation for patients with irritable bowel syndrome: A meta-analysis protocol

Irritable bowel syndrome (IBS) is a common functional bowel disease characterized by chronic or recurrent abdominal pain, bloating, constipation, and diarrhea. Many patients with IBS have a poor quality of life due to abdominal discomfort, diarrhea, constipation, and the presence of other diseases. At present, intestinal motility inhibitors, adsorbents, astringents, intestinal mucosal protective agents, and antidepressants have been combined to treat IBS, but the treatment process is long, which results in a large economic burden to patients. Fecal microbiota transplantation (FMT) is a treatment involving the transplantation of functional bacteria from healthy human feces into the gastrointestinal tract of patients; thus, replacing the intestinal flora and modulating intestinal and extra-intestinal diseases. In recent years, the efficacy and economic benefits of FMT in the treatment of IBS have received increasing attention from researchers.A search for randomized controlled trials (RCTs) on treating IBS with FMT will be performed using 9 databases, including PubMed, the Cochrane Library, Embase, ClinicalTrails, China National Knowledge Infrastructure, Sino Med, ScienceDirect, VIP, and Wanfang Data. Two reviewers will independently screen data extraction studies and assess study quality and risk of bias. The risk of bias for each RCT will be assessed against the Cochrane Handbook standards to assess methodological quality. RevMan V.5.3 software will be used to calculate data synthesis when meta-analysis is allowed.This study will provide a high-quality synthesis of existing evidence on the effectiveness and safety of FMT in the treatment of IBS.This study will determine if FMT is an effective and safe intervention for IBS.PROSPERO registration number is PROSPERO CRD42018108080.

Irritable bowel syndrome in children: Current knowledge, challenges and opportunities

Irritable bowel syndrome (IBS) is a common and troublesome disorder in children with an increasing prevalence noted during the past two decades. It has a significant effect on the lives of affected children and their families and poses a significant burden on healthcare systems. Standard symptom-based criteria for diagnosis of pediatric IBS have changed several times during the past two decades and there are some differences in interpreting symptoms between different cultures. This has posed a problem when using them to diagnose IBS in clinical practice. A number of potential patho-physiological mechanisms have been described, but so far the exact underlying etiology of IBS is unclear. A few potential therapeutic modalities have been tested in children and only a small number of them have shown some benefit. In addition, most of the described patho-physiological mechanisms and treatment options are based on adult studies. These have surfaced as challenges when dealing with pediatric IBS and they need to be overcome for effective management of children with IBS. Recently suggested top-down and bottom-up models help integrating reported patho-physiological mechanisms and will provide an opportunity for better understanding of the diseases process. Treatment trials targeting single treatment modalities are unlikely to have clinically meaningful therapeutic effects on IBS with multiple integrating patho-physiologies. Trials focusing on multiple combined pharmacological and non-pharmacological therapies are likely to yield more benefit. In addition to treatment, in the future, attention should be paid for possible prevention strategies for IBS.

Fecal microbiota transplantation for managing irritable bowel syndrome

Irritable bowel syndrome (IBS) is a widespread gastrointestinal disorder affecting 11.2% of the world adult population. The intestinal microbiome is thought to play a pivotal role in the pathophysiology of IBS. The composition of the fecal microbiome in IBS patients differs from that in healthy individuals, but the exact bacteria species involved in the development of IBS remain to be determined. There is also an imbalance between useful and harmful bacteria (dysbiosis) in the intestinal microbiome in patients with IBS. Consuming prebiotics, probiotics, or synbiotics has a limited effect on IBS symptoms. In contrast, fecal microbiome transplantation (FMT) in IBS patients reverses the dysbiosis to normobiosis and reduces the IBS symptoms in about 70% of patients, and is not associated with any serious adverse events. Area covered: The available data on the microbiome and FMT in IBS regarding the efficacy of FMT in managing IBS were found using a PubMed search of these topics. Expert commentary: FMT is a promising tool for managing irritable syndrome. It appears to be effective, easy, and inexpensive procedure. However, more controlled studies involving larger cohorts of IBS are needed before FMT can be used as a routine procedure in the clinic.

Antibiotic-mediated bacteriome depletion in ApcMin/+ mice is associated with reduction in mucus-producing goblet cells and increased colorectal cancer progression

Recent epidemiological evidence suggests that exposure to antibiotics in early‐to‐middle adulthood is associated with an increased risk of colorectal adenoma. However, mechanistic studies in established preclinical cancer to examine these claims are extremely limited. Therefore, we investigated the effect of long‐term exposure of an antibiotic cocktail composed of Vancomycin, Neomycin, and Streptomycin, on tumor development and progression in the Apc^Min/+ mouse, an established genetic model for familial adenomatous polyposis. Clinical pathologies related to tumor development as well as intestinal and colon tissue histopathology were studied at ages 8, 12, and 16 weeks of age, which correspond to the approximate ages of development of neoplasia, gut inflammation with polyposis, and cancer progression, respectively, in this animal model. We show that the antibiotics significantly increase the severity of clinical symptoms, including effects on intestinal histology and goblet cell numbers. In addition, they promote small intestinal polyposis. Finally, metagenomic analysis of fecal samples demonstrated that antibiotic exposure is associated with a significant but nonuniform depletion of the animal's natural gut flora. Overall, these findings support the premise that long‐term antibiotic exposure mediates the selected depletion of gut microbial communities and the concomitant thinning of the protective mucus layer, resulting in an increase in tumor development.

Functional abdominal pain disorders in children

Chronic abdominal pain is a common problem in pediatric practice. The majority of cases fulfill the Rome IV criteria for functional abdominal pain disorders (FAPDs). At times, these disorders may lead to rather serious repercussions. Area covered: We have attempted to cover current knowledge on epidemiology, pathophysiology, risk factors related to pathophysiology, clinical evaluation and management of children with FAPDs. Expert commentary: FAPDs are a worldwide problem with a pooled prevalence of 13.5%. There are a number of predisposing factors and pathophysiological mechanisms including stressful events, child maltreatment, visceral hypersensitivity, altered gastrointestinal motility and change in intestinal microbiota. It is possible that the environmental risk factors intricately interact with genes through epigenetic mechanisms to contribute to the pathophysiology. The diagnosis mainly depends on clinical evaluation. Commonly used pharmacological interventions do not play a major role in relieving symptoms. Centrally directed, nonpharmacological interventions such as hypnotherapy and cognitive behavioral therapy have shown both short and long term efficacy in relieving pain in children with FAPDs. However, these interventions are time consuming and need specially trained staff and therefore, not currently available at grass root level. Clinicians and researchers should join hands in searching for more pragmatic and effective therapeutic modalities to improve overall care of children with FAPDs.

The Problem of Curcumin and Its Bioavailability: Could Its Gastrointestinal Influence Contribute to Its Overall Health-Enhancing Effects?

Curcumin, from the spice turmeric, exhibits anti-inflammatory, antioxidant, anticancer, antiviral, and neurotrophic activity and therefore holds promise as a therapeutic agent to prevent and treat several disorders. However, a major barrier to curcumin's clinical efficacy is its poor bioavailability. Efforts have therefore been dedicated to developing curcumin formulations with greater bioavailability and systemic tissue distribution. However, it is proposed in this review that curcumin's potential as a therapeutic agent may not solely rely on its bioavailability, but rather its medicinal benefits may also arise from its positive influence on gastrointestinal health and function. In this review, in vitro, animal, and human studies investigating the effects of curcumin on intestinal microbiota, intestinal permeability, gut inflammation and oxidative stress, anaphylactic response, and bacterial, parasitic, and fungal infections are summarized. It is argued that positive changes in these areas can have wide-ranging influences on both intestinal and extraintestinal diseases, and therefore presents as a possible mechanism behind curcumin's therapeutic efficacy.

The Gut and Its Microbiome as Related to Central Nervous System Functioning and Psychological Well-being: Introduction to the Special Issue of Psychosomatic Medicine

Accumulating evidence indicates bidirectional associations between the brain and the gut microbiome with both top-down and bottom-up processes. This article describes new developments in brain-gut interactions as an introduction to a special issue of Psychosomatic Medicine, based on a joint symposium of the American Psychosomatic Society and the American Gastroenterological Association. Literature review articles indicate that several psychiatric disorders are associated with altered gut microbiota, whereas evidence linking functional gastrointestinal disorders and dysbiosis has not been firmly established. The association between dysbiosis with obesity, metabolic syndrome, and Type 2 diabetes mellitus is still inconclusive, but evidence suggests that bariatric surgery may favorably alter the gut microbial community structure. Consistent with the literature linking psychiatric disorders with dysbiosis is that life adversity during childhood and certain temperaments that develop early in life are associated with altered gut microbiota, particularly the Prevotella species. Some studies reported in this issue support the hypothesis that brain-gut interactions are adversely influenced by reduced functional activation of the hippocampus and autonomic nervous system dysregulation. The evidence for the effects of probiotics in the treatment of Clostridium difficile colitis is relatively well established, but effects on mental health and psychophysiological stress reactivity are either inconclusive or still in progress. To conceptualize brain-gut interactions, a holistic, systems-based perspective on health and disease is needed, integrating gut microbial with environmental ecology. More translational research is needed to examine the mental and physical health effects of prebiotics and probiotics, in well-phenotyped human populations with sufficiently large sample sizes.

Toward a Biopsychosocial Ecology of the Human Microbiome, Brain-Gut Axis, and Health

OBJECTIVE

Rapidly expanding insights into the human microbiome and health suggest that Western medicine is poised for significant evolution, or perhaps revolution-this while medicine continues on a trajectory from reductionism to a biopsychosocial (BPS) paradigm recognizing biological, psychological, and social influences on health. The apparent sensitivity of the microbiota to perturbations across BPS domains suggests that a broad and inclusive framework is needed to develop applicable knowledge in this emerging area. We outline an ecological framework of the human microbiome by extending the BPS concept to better incorporate environmental and human factors as members of a global, dynamic set of systems that interact over time.

METHODS

We conducted a selective literature review across disciplines to integrate microbiome research into a BPS framework.

RESULTS

The microbiome can be understood in terms of ecological systems encompassing BPS domains at four levels: (a) immediate (molecular, genetic, and neural processes), (b) proximal (physiology, emotion, social integration), (c) intermediate (built environments, behaviors, societal practices), and (d) distal (physical environments, attitudes, and broad cultural, economic, and political factors). The microbiota and host are thus understood in terms of their immediate interactions and the more distal physical and social arenas in which they participate.

CONCLUSIONS

A BPS ecological paradigm encourages replicable, generalizable, and interdisciplinary/transdisciplinary research and practices that take into account the vast influences on the human microbiome that may otherwise be overlooked or understood out of context. It also underscores the importance of sustainable bioenvironmental, psychological, and social systems that broadly support microbial, neural, and general health.

The role of microbiota in the pathogenesis of schizophrenia and major depressive disorder and the possibility of targeting microbiota as a treatment option

The importance of interactions between the brain and the gastrointestinal tract has been increasingly recognized in recent years. It has been proposed that dysregulation and abnormalities in the brain-gut axis contribute to the etiology of a variety of central nervous system disorders. Particularly, dysbiosis, or impaired microbiota, has been implicated in multiple neurological and psychological disorders. The present paper reviews current evidence and theories concerning the possible mechanisms by which microbiota dysfunction contributes to the pathogenesis of schizophrenia and major depressive disorder. Clinical trials that investigated the possibility of treating both illnesses by correcting and rebalancing microbiota with probiotics are also reviewed. Overall, despite the accumulated knowledge in this field, more studies are warranted and required to further our understanding of the brain-gut axis and the possibility of targeting microbiota as a treatment option for schizophrenia and major depressive disorder.