Dysbiosis: A Review Highlighting Obesity and Inflammatory Bowel Disease

Obesity and novel management of inflammatory bowel disease

Obesity is prevalent within the inflammatory bowel disease (IBD) population, particularly in newly developed countries. Several epidemiological studies have suggested that 15%-40% of IBD patients are obese, and there is a potential role of obesity in the pathogenesis of IBD. The dysfunction of mesenteric fat worsens the inflammatory course of Crohn’s disease and may induce formation of strictures or fistulas. Furthermore, obesity may affect the disease course or treatment response of IBD. Given the increasing data supporting the pathophysiologic and epidemiologic relationship between obesity and IBD, obesity control is being suggested as a novel management for IBD. Therefore, this review aimed to describe the influence of obesity on the outcomes of IBD treatment and to present the current status of pharmacologic or surgical anti-obesity treatments in IBD patients.

Prevalence and Implications of Shiga Toxin-Producing E. coli in Farm and Wild Ruminants

Shiga-toxin-producing Escherichia coli (STEC) is a food-borne pathogen that causes human gastrointestinal infections across the globe, leading to kidney failure or even death in severe cases. E. coli are commensal members of humans and animals' (cattle, bison, and pigs) guts, however, may acquire Shiga-toxin-encoded phages. This acquisition or colonization by STEC may lead to dysbiosis in the intestinal microbial community of the host. Wildlife and livestock animals can be asymptomatically colonized by STEC, leading to pathogen shedding and transmission. Furthermore, there has been a steady uptick in new STEC variants representing various serotypes. These, along with hybrids of other pathogenic E. coli (UPEC and ExPEC), are of serious concern, especially when they possess enhanced antimicrobial resistance, biofilm formation, etc. Recent studies have reported these in the livestock and food industry with minimal focus on wildlife. Disturbed natural habitats and changing climates are increasingly creating wildlife reservoirs of these pathogens, leading to a rise in zoonotic infections. Therefore, this review comprehensively surveyed studies on STEC prevalence in livestock and wildlife hosts. We further present important microbial and environmental factors contributing to STEC spread as well as infections. Finally, we delve into potential strategies for limiting STEC shedding and transmission.

Obesity in Inflammatory Bowel Disease Is Associated with Early Readmissions Characterised by an Increased Systems and Patient-level Burden

BACKGROUND AND AIMS

Rates of obesity are rising in patients with inflammatory bowel disease [IBD]. We conducted a US population-based study to determine the effects of obesity on outcomes in hospitalised patients with IBD.

METHODS

We searched the Nationwide Readmissions Database 2016-2017 to identify all adult patients hospitalised for IBD, using ICD-10 codes. We compared obese (body mass index [BMI] ≥ 30) vs non-obese [BMI < 30] patients with IBD to evaluate the independent effects of obesity on readmission, mortality, and other hospital outcomes. Multivariate regression and propensity matching were performed.

RESULTS

We identified 143 190 patients with IBD, of whom 9.1% were obese. Obesity was independently associated with higher all-cause readmission at 30 days {18% vs 13% (adjusted odds ratio [aOR] 1.16, p = 0.005)} and 90 days (29% vs 21% [aOR 1.27, p < 0.0001]), as compared with non-obese patients, with similar findings upon a propensity-matched sensitivity analysis. Obese and non-obese patients had similar risks of mortality on index admission [0.24% vs 0.31%, p = 0.18] and readmission [1.5% vs 1.8% p = 0.3]. Obese patients had longer [5.3 vs 4.9 days] and more expensive [USD12,195 vs USD11,154] hospitalisations on index admission. Obesity did not affect the risk of intestinal surgery or bowel obstruction. Compared with index admissions, readmissions were characterised by increased mortality [6-fold], health care use, and bowel obstruction [3-fold] [all p < 0.0001].

CONCLUSIONS

Obesity in IBD appears to be associated with increased early readmission, characterised by a higher burden, despite the introduction of weight-based therapeutics. Prevention of obesity should be a focus in the treatment of IBD to decrease readmission and health care burden.

Escherichia coli Shiga Toxins and Gut Microbiota Interactions

Escherichia coli (EHEC) and Shigella dysenteriae serotype 1 are enterohemorrhagic bacteria that induce hemorrhagic colitis. This, in turn, may result in potentially lethal complications, such as hemolytic uremic syndrome (HUS), which is characterized by thrombocytopenia, acute renal failure, and neurological abnormalities. Both species of bacteria produce Shiga toxins (Stxs), a phage-encoded exotoxin inhibiting protein synthesis in host cells that are primarily responsible for bacterial virulence. Although most studies have focused on the pathogenic roles of Stxs as harmful substances capable of inducing cell death and as proinflammatory factors that sensitize the host target organs to damage, less is known about the interface between the commensalism of bacterial communities and the pathogenicity of the toxins. The gut contains more species of bacteria than any other organ, providing pathogenic bacteria that colonize the gut with a greater number of opportunities to encounter other bacterial species. Notably, the presence in the intestines of pathogenic EHEC producing Stxs associated with severe illness may have compounding effects on the diversity of the indigenous bacteria and bacterial communities in the gut. The present review focuses on studies describing the roles of Stxs in the complex interactions between pathogenic Shiga toxin-producing E. coli, the resident microbiome, and host tissues. The determination of these interactions may provide insights into the unresolved issues regarding these pathogens.

Impact of Body Mass Index on the Development of Inflammatory Bowel Disease: A Systematic Review and Dose-Response Analysis of 15.6 Million Participants

Background: A growing trove of literature describes the effect of malnutrition and underweight on the incidence of inflammatory bowel disease (IBD). However, evidence regarding the association between underweight or obesity and IBD is limited. The study aimed to assess the association of body mass index (BMI) with a risk of IBD (Crohn’s disease (CD) and ulcerative colitis (U.C.)) incidence. Methods: We systematically searched PubMed/Medline, Cochrane, Web of Science, and Scopus for observational studies assessing the association between BMI and IBD that were published up to 30 June 2020. We estimated pooled hazard ratios (HR) with corresponding 95% confidence intervals (CI). Random effect dose-response meta-analysis was performed using the variance weighted least-squares regression (VWLS) models to identify non-linear associations. Results: A total of ten studies involving 15.6 million individuals and 23,371 cases of IBD were included. Overall, obesity was associated with an increased IBD risk (HR: 1.20, 95% CI: 1.08–1.34, I² = 0%). Compared to normal weight, underweight (BMI < 18.5 kg/m²) and obesity (BMI ≥ 30 kg/m²) were associated with a higher risk of CD, and there was no difference in the risk of U.C. among those with BMI < 18.5 kg/m² and BMI ≥ 30 kg/m². There was a significant non-linear association between being underweight and obesity and the risk of development of CD (Coef₁ = −0.0902, p₁ < 0.001 Coef₂ = 0.0713, p₂ < 0.001). Conclusions: Obesity increases the risk of IBD development. Underweight and obesity are independently associated with an increased risk of CD, yet there is no evident association between BMI and the risk of U.C. Further studies are needed to clarify the underlying mechanism for these findings, particularly in CD.

Role of Obesity, Mesenteric Adipose Tissue, and Adipokines in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs) are a group of disorders which include ulcerative colitis and Crohn's disease. Obesity is becoming increasingly more common among patients with inflammatory bowel disease and plays a role in the development and course of the disease. This is especially true in the case of Crohn's disease. The recent results indicate a special role of visceral adipose tissue and particularly mesenteric adipose tissue, also known as "creeping fat", in pathomechanism, leading to intestinal inflammation. The involvement of altered adipocyte function and the deregulated production of adipokines, such as leptin and adiponectin, has been suggested in pathogenesis of IBD. In this review, we discuss the epidemiology and pathophysiology of obesity in IBD, the influence of a Western diet on the course of Crohn's disease and colitis in IBD patients and animal's models, and the potential role of adipokines in these disorders. Since altered body composition, decrease of skeletal muscle mass, and development of pathologically changed mesenteric white adipose tissue are well-known features of IBD and especially of Crohn's disease, we discuss the possible crosstalk between adipokines and myokines released from skeletal muscle during exercise with moderate or forced intensity. The emerging role of microbiota and the antioxidative and anti-inflammatory enzymes such as intestinal alkaline phosphatase is also discussed, in order to open new avenues for the therapy against intestinal perturbations associated with IBD.

The effect of multistrain probiotic supplementation in two doses on iron metabolism in obese postmenopausal women: a randomized trial

Obesity leads to detrimental abnormalities of iron (Fe) metabolism. So far, studies have shown that single-strain probiotic supplementation ameliorates the gut microbiota quality disrupted in the obese and improves Fe homeostasis. The effect of multistrain probiotic supplementation and its dose-dependence in obese postmenopausal women remain unknown. The study aimed to investigate the effect of multistrain probiotic supplementation in two doses on selected parameters of Fe metabolism in obese postmenopausal female patients. Three groups of obese postmenopausal women, 30 subjects each, received nine-strain oral probiotic supplement at a daily dose of 2.5 × 10⁹ CFU (LD group), 1 × 10¹⁰ CFU (HD group), or placebo for 12 weeks (ClinicalTrails.gov no: NCT03100162). After the intervention, the hair Fe content was lower in both supplemented groups compared to the baseline, the serum zinc (Zn) concentration was higher in the LD group and lower in the HD group vs. the baseline, and the serum erythroferrone (FAM) concentration was lower in the HD group and serum ferritin (FE) concentration was higher in the LD group vs. the baseline. In the whole study population after the completion of the intervention hair Zn correlated positively with serum HEPC and FAM and negatively with serum FE. Hair Fe correlated negatively with serum FE. It is concluded that multistrain probiotic supplementation may influence iron metabolism in obese postmenopausal female patients.

Air Pollution, Early Life Microbiome, and Development

PURPOSE OF REVIEW

We review how an altered microbiome in early life impacts on immune, metabolic, and neurological development, focusing on some of the most widespread diseases related to each of these processes, namely atopic disease, obesity, and autism.

RECENT FINDINGS

The early development of the microbial communities that inhabit the human body is currently challenged by factors that range from reduced exposure to microbes, antibiotic use, and poor dietary choices to widespread environmental pollution. Recent work has highlighted some of the long-term consequences that early alterations in the establishment of these microbiotas can have for different aspects of human development and health. The long-term consequences of early microbiome alterations for human development and health are only beginning to be understood and will require in-depth investigation in the years to come. A solid understanding of how present day environmental conditions alter microbiome development, and of how an altered microbiome in early life impacts on life-long health, should inform both public health policies and the development of dietary and medical strategies to counteract early microbiota imbalances.

Review article: the relationship between obesity, bariatric surgery, and inflammatory bowel disease

BACKGROUND

The convoluted relationship between obesity, bariatric surgery and inflammatory bowel disease (IBD) is of increasing interest.

AIM

To analyse evidence regarding the role of bariatric surgery in the development of de novo IBD and its impact on clinical outcomes and safety in patients with established IBD.

METHODS

A PubMed/Medline search was performed to identify studies reporting the development of IBD after bariatric surgery and the outcomes of IBD patients after bariatric surgery.

RESULTS

Eighty patients were reported to have developed de novo IBD after bariatric surgery (21% ulcerative colitis [UC], 75% Crohn's disease [CD]), mostly females. Roux-en-Y gastric bypass was the most frequent bariatric technique (80%). Symptoms related to IBD occurred within 1 month and 16 years after surgery. Regarding patients with known IBD undergoing bariatric surgery, 60 patients (35 CD, 24 UC, and 1 unclassified colitis) have been reported. Sleeve gastrectomy was the most frequent bariatric procedure, particularly in CD patients. Acute flares after surgery were observed in only four UC patients. In addition, two retrospective population-based studies described perioperative outcomes of bariatric surgery on IBD patients, demonstrating only a significant increase in small bowel obstruction in these patients.

CONCLUSIONS

Bariatric surgery in carefully selected patients with established IBD is technically feasible and probably safe. Development of de novo IBD should be taken into account in individuals with previous bariatric surgery who develop diarrhoea, anaemia or excessive weight loss.

The First Microbial Colonizers of the Human Gut: Composition, Activities, and Health Implications of the Infant Gut Microbiota

The human gut microbiota is engaged in multiple interactions affecting host health during the host's entire life span. Microbes colonize the neonatal gut immediately following birth. The establishment and interactive development of this early gut microbiota are believed to be (at least partially) driven and modulated by specific compounds present in human milk. It has been shown that certain genomes of infant gut commensals, in particular those of bifidobacterial species, are genetically adapted to utilize specific glycans of this human secretory fluid, thus representing a very intriguing example of host-microbe coevolution, where both partners are believed to benefit. In recent years, various metagenomic studies have tried to dissect the composition and functionality of the infant gut microbiome and to explore the distribution across the different ecological niches of the infant gut biogeography of the corresponding microbial consortia, including those corresponding to bacteria and viruses, in healthy and ill subjects. Such analyses have linked certain features of the microbiota/microbiome, such as reduced diversity or aberrant composition, to intestinal illnesses in infants or disease states that are manifested at later stages of life, including asthma, inflammatory bowel disease, and metabolic disorders. Thus, a growing number of studies have reported on how the early human gut microbiota composition/development may affect risk factors related to adult health conditions. This concept has fueled the development of strategies to shape the infant microbiota composition based on various functional food products. In this review, we describe the infant microbiota, the mechanisms that drive its establishment and composition, and how microbial consortia may be molded by natural or artificial interventions. Finally, we discuss the relevance of key microbial players of the infant gut microbiota, in particular bifidobacteria, with respect to their role in health and disease.

Nopal feeding reduces adiposity, intestinal inflammation and shifts the cecal microbiota and metabolism in high-fat fed rats

Nopal is a cactus plant widely consumed in Mexico that has been used in traditional medicine to aid in the treatment of type-2 diabetes. We previously showed that chronic consumption of dehydrated nopal ameliorated hepatic steatosis in obese (fa/fa) rats; however, description of the effects on other tissues is sparse. The aim of the present study was to investigate the effects of nopal cladode consumption on intestinal physiology, microbial community structure, adipose tissue, and serum biochemistry in diet-induced obese rats. Rats were fed either a normal fat (NF) diet or a HF diet containing 4% of dietary fiber from either nopal or cellulose for 6 weeks. Consumption of nopal counteracted HF-induced adiposity and adipocyte hypertrophy, and induced profound changes in intestinal physiology. Nopal consumption reduced biomarkers of intestinal inflammation (mRNA expression of IL-6) and oxidative stress (ROS), modfied gut microbiota composition, increasing microbial diversity and cecal fermentation (SCFA), and altered the serum metabolome. Interestingly, metabolomic analysis of dehydrated nopal revealed a high choline content, which appeared to generate high levels of serum betaine, that correlated negatively with hepatic triglyceride (TAG) levels. A parallel decrease in some of the taxa associated with the production of trimethylamine, suggest an increase in choline absorption and bioavailability with transformation to betaine. The latter may partially explain the previously observed effect of nopal on the development of hepatic steatosis. In conclusion, this study provides new evidence on the effects of nopal consumption on normal and HF-diet induced changes in the intestine, the liver and systemic metabolism.

Obesity in IBD: epidemiology, pathogenesis, disease course and treatment outcomes

Incidence of IBD is rising in parallel with overweight and obesity. Contrary to conventional belief, about 15-40% of patients with IBD are obese, which might contribute to the development of IBD. Findings from cross-sectional and retrospective cohort studies are conflicting on the effect of obesity on natural history and course of IBD. Most studies are limited by small sample size, low event rates, non-validated assessment of disease activity and lack robust longitudinal follow-up and have incomplete adjustment for confounding factors. The effect of obesity on the efficacy of IBD-related therapy remains to be studied, though data from other autoimmune diseases suggests that obesity results in suboptimal response to therapy, potentially by promoting rapid clearance of biologic agents leading to low trough concentrations. These data provide a rationale for using weight loss interventions as adjunctive therapy in patients with IBD who are obese. Obesity also makes colorectal surgery technically challenging and might increase the risk of perioperative complications. In this Review, we highlight the existing literature on the epidemiology of obesity in IBD, discuss its plausible role in disease pathogenesis and effect on disease course and treatment response, and identify high-priority areas of future research.

Dietary silver nanoparticles can disturb the gut microbiota in mice

Background

Humans are increasingly exposed via the diet to Ag nanoparticles (NP) used in the food industry. Because of their anti-bacterial activity, ingested Ag NP might disturb the gut microbiota that is essential for local and systemic homeostasis. We explored here the possible impact of dietary Ag NP on the gut microbiota in mice at doses relevant for currently estimated human intake.

Methods

Mice were orally exposed to food (pellets) supplemented with increasing doses of Ag NP (0, 46, 460 or 4600 ppb) during 28 d. Body weight, systemic inflammation and gut integrity were investigated to determine overall toxicity, and feces DNA collected from the gut were analyzed by Next Generation Sequencing (NGS) to assess the effect of Ag NP on the bacterial population. Ag NP were characterized alone and in the supplemented pellets by scanning transmission electron microscopy (STEM) and energy dispersive X-ray analysis (EDX).

Results

No overall toxicity was recorded in mice exposed to Ag NP. Ag NP disturbed bacterial evenness (α-diversity) and populations (β-diversity) in a dose-dependent manner. Ag NP increased the ratio between Firmicutes (F) and Bacteroidetes (B) phyla. At the family level, Lachnospiraceae and the S24-7 family mainly accounted for the increase in Firmicutes and decrease in Bacteroidetes, respectively. Similar effects were not observed in mice identically exposed to the same batch of Ag NP-supplemented pellets aged during 4 or 8 months and the F/B ratio was less or not modified. Analysis of Ag NP-supplemented pellets showed that freshly prepared pellets released Ag ions faster than aged pellets. STEM-EDX analysis also showed that Ag sulfidation occurred in aged Ag NP-supplemented pellets.

Conclusions

Our data indicate that oral exposure to human relevant doses of Ag NP can induce microbial alterations in the gut. The bacterial disturbances recorded after Ag NP are similar to those reported in metabolic and inflammatory diseases, such as obesity. It also highlights that Ag NP aging in food, and more specifically sulfidation, can reduce the effects of Ag NP on the microbiota by limiting the release of toxic Ag ions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-016-0149-1) contains supplementary material, which is available to authorized users.

Recommendations for Probiotic Use--2015 Update: Proceedings and Consensus Opinion

This paper describes the consensus opinion of the participants in the 4th Triennial Yale/Harvard Workshop on Probiotic Recommendations. The recommendations update those of the first 3 meetings that were published in 2006, 2008, and 2011. Recommendations for the use of probiotics in necrotizing enterocolitis, childhood diarrhea, inflammatory bowel disease, irritable bowel syndrome and Clostridium difficile diarrhea are reviewed. In addition, we have added recommendations for liver disease for the first time. As in previous publications, the recommendations are given as A, B, or C ratings.