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1.
Purpose of Review
Obesity and diabetes are worldwide epidemics. There is also a growing body of evidence relating the gut microbiome composition to insulin resistance. The purpose of this review is to delineate the studies linking gut microbiota to obesity, metabolic syndrome, and diabetes.Recent findings
Animal studies as well as proof of concept studies using fecal transplantation demonstrate the pivotal role of the gut microbiota in regulating insulin resistance states and inflammation.Summary
While we still need to standardize methodologies to study the microbiome, there is an abundance of evidence pointing to the link between gut microbiome, inflammation, and insulin resistance, and future studies should be aimed at identifying unifying mechanisms.2.
Background
The gut microbiome has emerged as a key player in the modulation of the immune system and metabolism. Changes in the composition of the gut microbial ecosystems have been reported to be associated with metabolic diseases but also with the development and progression of cardiovascular diseases, inflammatory bowel disease, certain types of cancer and psychiatric diseases.Objective
The role of the gut microbiome in the pathophysiology of obesity and type 2 diabetes, and treatment approaches based thereon are discussed.Microbiome and pathophysiology
The pathophysiology in humans is not entirely understood. Studies in mice suggest a strong causal link between changes in the microbiome and the development of metabolic diseases. Potential mechanisms how the microbiome is linked to diseases of the host include signaling through lipopolysaccharides from gram-negative bacteria and interactions with the host immune system, fermentation of indigestible fiber to short chain fatty acids, modulation of bile acids, and bile acid signaling. Interactions between gut microbiota, its products, and the immune system may lead to an increased gut permeability resulting in visceral fat and liver inflammation with subsequent systemic subclinical inflammation (leaky gut hypothesis). Moreover, host-specific factors and environmental factors have been discussed to have a role.Conclusion
Increasing knowledge in this area could contribute to the treatment of obesity and type 2 diabetes with fecal or targeted microbiota transplantation.3.
Elke Gülden 《Current diabetes reports》2018,18(11):111
Purpose of Review
The incidence of type 1 diabetes (T1D) is rising drastically for the past decades at a rate that cannot be explained by genetic changes alone. Environmental changes are considered to be the main drivers of this change. Recently, the gut microbiota has been suggested as a missing link between known environmental disease modulators and T1D promotion. Lifestyle factors have changed over time and have altered the gut microbiota-host interaction affecting T1D development. The purpose of this review is to discuss recent data emphasizing the modulatory potential of early lifestyle factors on gut microbiota and to elucidate their implication for T1D.Recent Findings
Recent findings show that lifestyle factors, especially those that affect the early establishment of gut homeostasis and the education of the immune system, are crucial disease modulators.Summary
Changing lifestyle factors affecting the early establishment of gut homeostasis are suggested to be key drivers of the rising T1D incidence.4.
Antonio Sircana Luciana Framarin Nicola Leone Mara Berrutti Francesca Castellino Renato Parente Franco De Michieli Elena Paschetta Giovanni Musso 《Current diabetes reports》2018,18(10):98
Purpose of Review
In the last decade many studies have suggested an association between the altered gut microbiota and multiple systemic diseases including diabetes. In this review, we will discuss potential pathophysiological mechanisms, the latest findings regarding the mechanisms linking gut dysbiosis and type 2 diabetes (T2D), and the results obtained with experimental modulation of microbiota.Recent Findings
In T2D, gut dysbiosis contributes to onset and maintenance of insulin resistance. Different strategies that reduce dysbiosis can improve glycemic control.Summary
Evidence in animals and humans reveals differences between the gut microbial composition in healthy individuals and those with T2D. Changes in the intestinal ecosystem could cause inflammation, alter intestinal permeability, and modulate metabolism of bile acids, short-chain fatty acids and metabolites that act synergistically on metabolic regulation systems contributing to insulin resistance. Interventions that restore equilibrium in the gut appear to have beneficial effects and improve glycemic control. Future research should examine in detail and in larger studies other possible pathophysiological mechanisms to identify specific pathways modulated by microbiota modulation and identify new potential therapeutic targets.5.
Trine B. Rounge Roger Meisal Jan Inge Nordby Ole Herman Ambur Thomas de Lange Geir Hoff 《BMC gastroenterology》2018,18(1):171
Background
Associations between colorectal cancer and microbiota have been identified. Archived fecal samples might be valuable sample sources for investigating causality in carcinogenesis and biomarkers discovery due to the potential of performing longitudinal studies. However, the quality, quantity and stability of the gut microbiota in these fecal samples must be assessed prior to such studies. We evaluated i) cross-contamination during analysis for fecal blood and ii) evaporation in stored perforated fecal immunochemical tests (iFOBT) samples, iii) temperature stability as well as iv) comparison of the gut microbiota diversity and composition in archived, iFOBT and fresh fecal samples in order to assess feasibility of large scale microbiota studies.Methods
The microbiota profiles were obtained by sequencing the V3-V4 region of 16S rDNA gene.Results
The iFOBT does not introduce any cross-sample contamination detectable by qPCR. Neither could we detect evaporation during freeze-thaw cycle of perforated iFOBT samples. Our results confirm room temperature stability of the gut microbiome. Diverse microbial profiles were achieved in 100% of fresh, 81% of long-term archived and 96% of iFOBT samples. Microbial diversity and composition were comparable between fresh and iFOBT samples, however, diversity differed significantly between long-term archived, fresh and iFOBT samples.Conclusion
Our data showed that it is feasible to exploit archived fecal sample sets originally collected for testing of fecal blood. The advantages of using these sample sets for microbial biomarker discovery and longitudinal observational studies are the availability of high-quality diagnostic and follow-up data. However, care must be taken when microbiota are profiled in long-term archived fecal samples.6.
Purpose of Review
The microbiome is the term that describes the microbial ecosystem that cohabits an organism such as humans. The microbiome has been implicated in a long list of immune-mediated diseases which include rheumatoid arthritis, ankylosing spondylitis, and even gout. The mechanisms to account for this effect are multiple. The clinical implications from observations on the microbiome and disease are broad.Recent Findings
A growing number of microbiota constituents such as Prevotella copri, Porphyromonas gingivalis, and Collinsella have been correlated or causally related to rheumatic disease. The microbiome has a marked effect on the immune system. Our understanding of immune pathways modulated by the microbiota such as the induction of T helper 17 (Th17) cells and secretory immunoglobulin A (IgA) responses to segmented filamentous bacteria continues to expand. In addition to the gut microbiome, bacterial communities of other sites such as the mouth, lung, and skin have also been associated with the pathogenesis of rheumatic diseases.Summary
Strategies to alter the microbiome or to alter the immune activation from the microbiome might play a role in the future therapy for rheumatic diseases.7.
Background
The intestinal microbiome plays an essential role in the development of chronic inflammatory diseases, such as inflammatory bowel disease (IBD) or metabolic disorders.Objectives
What is the pathophysiological role of the intestine as an interface between bacterial and host functions?Methods
Recent findings related to intestinal function and microbe–host interactions in the context of inflammatory and metabolic disorders are reviewed.Results and conclusions
Changes in gut microbiota composition and function (dysbiosis) are associated with a variety of different pathologies. Dysbiosis in combination with the loss of gut barrier and immune functions are shared in inflammatory and metabolic disorders. Causal mechanisms for the interaction of dysbiotic microbial communities in the gut and disease onset require additional clinical and experimental validation including prospective cohort and gnotobiotic animal studies. Fecal microbiota transplantation and targeted microbial therapies are promising strategies for clinical intervention; however many questions need to be addressed including disease-specific selection of donor microbiota or synthetic bacterial consortia, application strategies and risk evaluation.8.
Sridharan Raghavan Mark C. Pachucki Yuchiao Chang Bianca Porneala Caroline S. Fox Josée Dupuis James B. Meigs 《Journal of general internal medicine》2016,31(10):1127-1133
BACKGROUND
Obesity and diabetes family history are the two strongest risk factors for type 2 diabetes (T2D). Prior work shows that an individual’s obesity risk is associated with obesity in social contacts, but whether T2D risk follows similar patterns is unknown.OBJECTIVE
We aimed to estimate the relationship between obesity or diabetes in an individual’s social contacts and his/her T2D risk. We hypothesized that obesity and diabetes in social contacts would increase an individual’s T2D risk.DESIGN
This was a retrospective analysis of the community-based Framingham Offspring Study (FOS).PARTICIPANTS
FOS participants with T2D status, height and weight, and at least one social contact were eligible for this study (n?=?4797 at Exam 1). Participants’ interpersonal ties, cardiometabolic and demographic variables were available at eight exams from 1971 to 2008, and a T2D additive polygenic risk score was measured at the fifth exam.MAIN MEASURES
Primary exposures were T2D (fasting glucose?≥?7 mmol/L or taking diabetes medications) and obesity status (BMI?≥?30 kg/m2) of social contacts at a prior exam. Primary outcome was incident T2D in participants.KEY RESULTS
Incident T2D was associated with having a social contact with diabetes (OR 1.32, p?=?0.004) or with obesity (OR 1.21, p?=?0.004). In stratified analyses, incident T2D was associated with diabetes in siblings (OR 1.64, p?=?0.001) and obesity in spouses (OR 1.54, p =?0.0004). The associations between diabetes and obesity in social contacts and an individual’s incident diabetes risk were stronger in individuals with a high diabetes genetic risk score.CONCLUSIONS
T2D and obesity in social contacts, particularly siblings and spouses, were associated with an individual’s risk of incident diabetes even after accounting for parental T2D history. Assessing risk factors in an individual’s siblings and spouses can inform T2D risk; furthermore, social network based lifestyle interventions involving spouses and siblings might be a novel T2D prevention approach.9.
Purpose of Review
Resident microbial communities likely modify risk for allergic disorders, including food allergy. We review epidemiologic studies linking microbial exposures to food allergy risk and discuss the mechanisms by which the microbiome may modulate oral tolerance. We additionally address ongoing translational efforts in human microbiome studies.Recent Findings
Epidemiologic studies and murine models support that altered microbial exposures and colonization in early life modify food allergy risk. Differential microbiota confer protection or susceptibility to food allergy by modulating the regulatory tone of the mucosal immune system. Recent efforts are focused on the identification of bacterial strains necessary for oral tolerance in human and microbial-based clinical trials.Summary
Early childhood appears to be critical for the colonization of a diverse microbiota necessary for the induction and maintenance of oral tolerance. Identification and functional evaluation of protective commensal microbes will inform strategies for the prevention and treatment of food allergy.10.
M. Blaut 《Der Diabetologe》2016,12(6):394-400
Background
Nutrition affects the composition of the intestinal microbiota and the spectrum and the amount of short-chain fatty acids produced in the colon.Short-chain fatty acids
Besides their role as an energy source, short-chain fatty acids have regulatory functions in the host. Thus, acetate serves as a building block in lipogenesis and propionate in gluconeogenesis. However, short-chain fatty acids they are also ligands of receptors that may play a role in the regulation of host energy metabolism.The microbiome and obesity
Obesity can be transferred to germfree mice by transplanting the intestinal microbiota from obese humans or rodents. There are some hints that certain members of the intestinal microbiota promote obesity and metabolic disease while others do the opposite. The underlying mechanisms are largely unknown.11.
Omar Youssef Leo Lahti Arto Kokkola Tiina Karla Milja Tikkanen Homa Ehsan Monika Carpelan-Holmström Selja Koskensalo Tom Böhling Hilpi Rautelin Pauli Puolakkainen Sakari Knuutila Virinder Sarhadi 《Digestive diseases and sciences》2018,63(11):2950-2958
Background
Microbial ecosystems that inhabit the human gut form central component of our physiology and metabolism, regulating and modulating both health and disease. Changes or disturbances in the composition and activity of this gut microbiota can result in altered immunity, inflammation, and even cancer.Aim
To compare the composition and diversity of gut microbiota in stool samples from patient groups based on the site of neoplasm in the gastrointestinal tract (GIT) and to assess the possible contribution of the bacterial composition to tumorigenesis.Methods
We studied gut microbiota by16S RNA gene sequencing from stool DNA of 83 patients, who were diagnosed with different GIT neoplasms, and 13 healthy individuals.Results
As compared to healthy individuals, stools of patients with stomach neoplasms had elevated levels of Enterobacteriaceae, and those with rectal neoplasms had lower levels of Bifidobacteriaceae. Lower abundance of Lactobacillaceae was seen in patients with colon neoplasms. Abundance of Lactobacillaceae was higher in stools of GIT patients sampled after cancer treatment compared to samples collected before start of any treatment. In addition to site-specific differences, higher abundances of Ruminococcus, Subdoligranulum and lower abundances of Lachnoclostridium and Oscillibacter were observed in overall GIT neoplasms as compared to healthy controlsConclusion
Our study demonstrates that the alterations in gut microbiota vary according to the site of GIT neoplasm. The observed lower abundance of two common families, Lactobacillaceae and Bifidobacteriaceae, and the increased abundance of Enterobacteriaceae could provide indicators of compromised gut health and potentially facilitate GIT disease monitoring.12.
Mitsuaki Ishioka Kouichi Miura Shinichiro Minami Yoichiro Shimura Hirohide Ohnishi 《Digestive diseases and sciences》2017,62(2):396-406
Background
Although several types of diet have been used in experimental steatohepatitis models, comparison of gut microbiota and immunological alterations in the gut among diets has not yet been performed.Aim
We attempted to clarify the difference in the gut environment between mice administrated several experimental diets.Methods
Male wild-type mice were fed a high-fat (HF) diet, a choline-deficient amino acid-defined (CDAA) diet, and a methionine-choline-deficient (MCD) diet for 8 weeks. We compared the severity of steatohepatitis, the composition of gut microbiota, and the intestinal expression of interleukin (IL)-17, an immune modulator.Results
Steatohepatitis was most severe in the mice fed the CDAA diet, followed by the MCD diet, and the HF diet. Analysis of gut microbiota showed that the composition of the Firmicutes phylum differed markedly at order level between the mice fed the CDAA and HF diet. The CDAA diet increased the abundance of Clostridiales, while the HF diet increased that of lactate-producing bacteria. In addition, the CDAA diet decreased the abundance of lactate-producing bacteria and antiinflammatory bacterium Parabacteroides goldsteinii in the phylum Bacteroidetes. In CDAA-fed mice, IL-17 levels were increased in ileum as well as portal vein. In addition, the CDAA diet also elevated hepatic expression of chemokines, downstream targets of IL-17.Conclusions
The composition of gut microbiota and IL-17 expression varied considerably between mice administrated different experimental diets to induce steatohepatitis.13.
Definition of terms
Under the term non-alcoholic fatty liver disease (NAFLD) both simple hepatic fat accumulation and non-alcoholic steatohepatitis (NASH) are combined. NASH is associated with liver fibrosis, cirrhosis and hepatocellular carcinoma (HCC).Epidemiological importance
In 2020, NAFLD will be the leading cause for liver transplantation in the USA, with rising financial costs for the healthcare system.Comorbidities, diagnosis, and treatment
Type 2 diabetes (T2D) and metabolic syndrome (MetS) are important risk factors for the development of NAFLD, whereby these three diseases share similar pathophysiologic conditions, e.g., insulin resistance, obesity, and metabolic inflammation. Due to the rising number of patients with T2D and MetS, clinicians should aim to diagnose NAFLD early in this patient population and if necessary start treatment.Goal
The aim of this work is to give an overview over the topic of NAFLD and diagnostic approaches in patients with T2D.14.
Lena M. Biehl Rebeca Cruz Aguilar Fedja Farowski Werner Hahn Angela Nowag Hilmar Wisplinghoff Maria J. G. T. Vehreschild 《Infection》2018,46(6):871-874
Purpose
We report on a kidney transplant recipient treated with fecal microbiota transplantation (FMT) for recurrent urinary tract infections.Methods
FMT was administered via frozen capsulized microbiota. Before and after FMT, urinary, fecal and vaginal microbiota compositions were analyzed.Results
The patient remained without symptoms after FMT.Conclusions
Underlying mechanisms of action need to be addressed in depth by future research.15.
Zhou Feng Wenmin Long Binhan Hao Ding Ding Xiaoqing Ma Liping Zhao Xiaoyan Pang 《Gut pathogens》2017,9(1):59
Background
Bilophila wadsworthia is a major member of sulfidogenic bacteria in human gut, it was originally recovered from different clinical specimens of intra-abdominal infections and recently was reported potentially linked to different chronic metabolic disorders. However, there is still insufficient understanding on its detailed function and mechanism to date.Methods
A B. wadsworthia strain was isolated from fresh feces of a latent autoimmune diabetes in adults patient and we investigated its pathogenicity by oral administration to specific-pathogen-free mice. Tissue samples and serum were collected after sacrifice. Stool samples were collected at different time points to profile the gut microbiota.Results
Bilophila wadsworthia infection resulted in the reduction of body weight and fat mass, apparent hepatosplenomegaly and elevated serum inflammatory factors, including serum amyloid A and interleukin-6, while without significant change of the overall gut microbiota structure.Conclusions
These results demonstrated that higher amount of B. wadsworthia caused systemic inflammatory response in SPF mice, which adds new evidence to the pathogenicity of this bacterium and implied its potential role to the chronic inflammation related metabolic diseases like diabetes.16.
Marta Olivares Audrey M. Neyrinck Sarah A. Pötgens Martin Beaumont Nuria Salazar Patrice D. Cani Laure B. Bindels Nathalie M. Delzenne 《Diabetologia》2018,61(8):1838-1848
Aims/hypothesis
Dipeptidyl peptidase 4 (DPP-4) inhibitors are agents designed to increase the half-life of incretins. Although they are administered orally, little is known about their effects on the gut microbiota and functions, despite the fact that some bacteria present in the gut microbiota exhibit DPP-4-like activity. Our objective was to study the impact of the DPP-4 inhibitor vildagliptin on gut functions and the intestinal ecosystem in a murine model of obesity induced by a Western diet (WD).Methods
Twenty seven male C57BL/6J mice were randomised to receive a control diet, a WD (45% kJ from fat and 17% kJ from sucrose) or a WD + vildagliptin (0.6 mg/ml in drinking water) for 8 weeks.Results
Vildagliptin significantly reduced DPP-4 activity in the caecal content and faeces. Vildagliptin impacted on the composition of the gut microbiota and its metabolic activity. It mainly decreased Oscillibacter spp. (a direct effect independent of DPP-4 activity was shown on cultured O. valericigenes), increased Lactobacillus spp. and propionate, and reduced the ligands of Toll-like receptors 2 and 4. Vildagliptin protected against the reductions in crypt depth and ileal expression of antimicrobial peptides induced by the WD. In the liver, the expression of immune cell populations (Cd3g and Cd11c [also known as Itgax]) and cytokines was decreased in the WD + vildagliptin-fed mice compared with the WD-fed group. Ex vivo exposure of precision-cut liver slices to vildagliptin showed that this response was not related to a direct effect of the drug on the liver tissue.Conclusions/interpretation
Our study is the first to consider the DPP-4-like activity of the gut microbiota as a target of DPP-4 inhibition. We propose that vildagliptin exerts beneficial effects at the intestinal level in association with modulation of gut microbiota, with consequences for hepatic immunity. If relevant in humans, this could open new therapeutic uses of DPP-4 inhibition to tackle gut dysfunctions in different pathophysiological contexts.Data availability
The sequences used for analysis can be found in the MG-RAST database under the project name MYNEWGUT3.17.
Xiuli Xiao Wenbo Long Tingyu Huang Tian Xia Rupei Ye Yong Liu Hanan Long 《Digestive diseases and sciences》2018,63(11):2923-2929
Background
Multiple factors including host–microbiota interaction could contribute to the conversion of healthy mucosa to sporadic precancerous lesions. An imbalance of the gut microbiota may be a cause or consequence of this process.Aim
The goal was to investigate and analyze the composition of gut microbiota during the genesis of precancerous lesions of colorectal cancer.Methods
To analyze the composition of gut microbiota in the genesis of precancerous lesions, a rat model of 1, 2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) was established. The feces of these rats and healthy rats were collected for 16S rRNA sequencing.Results
The diversity and density of the rat intestinal microbiota were significantly different between ACF-bearing and non-bearing group. ACF were induced in rats treated with DMH and showed increased expression of the inflammatory cytokines IL-6, IL-8, and TNF-α. Firmicutes was the most predominant phylum in both ACF-bearing and non-bearing group, followed by Bacteroidetes. Interestingly, although the density of Bacteroidetes decreased from the fifth week to the 17th week in both groups, it was significantly reduced in ACF-bearing group at the 13th week (P?<?0.01). At the genus level, no significant difference was observed in the most predominant genus, Lactobacillus. Instead, Bacteroides and Prevotella were significantly less abundant (P?<?0.01), while Akkermansia was significantly more abundant (P?<?0.05) in ACF-bearing group at the 13th week.Conclusion
Imbalance of the intestinal microbiota existed between ACF-bearing and non-bearing rats, which could be used as biomarker to predict the genesis of precancerous lesions in the gut.18.
Purpose of Review
The prevalence of combined obesity and diabetes has increased dramatically in the last few decades. Although medical and surgical weight management are variably effective in addressing this epidemic, it is essential to parallel these strategies with a hypocaloric diet comprising the appropriate macronutrient composition to induce weight loss, enhance glycemic control, and improve cardiovascular risk factors. This review reports the current evidence of the role of carbohydrates and fat-based diets for weight management in patients with combined type 2 diabetes (T2D) and obesity.Recent Findings
Low-carbohydrate diets were shown to decrease postprandial glucose levels whereas high-carbohydrate, low-fat diets are considered cardio-protective.Summary
A diet with an optimal macronutrient composition remains uncertain for patients with combined T2D and obesity. Further research is still needed to define the best dietary composition that achieves the maximum benefits on weight management, glycemic control, and cardiovascular risk factors.19.
Purpose of Review
Obesity and type 2 diabetes (T2D) are closely linked metabolic diseases. Most individuals with T2D are overweight or obese, which raises their cardiovascular risk. The etiology of both diseases is multifaceted, thus requiring a multidisciplinary approach to control them. This review describes the most effective multidisciplinary approach to weight management in patients with T2D in real-world clinical practice.Recent Findings
Weight management programs in real-world clinical settings lead to long-term weight loss for up to 5 years.Summary
Multidisciplinary approach to manage obesity and T2D through weight reduction is feasible in real-world clinical practice and is recommended as part of the treatment plan for patients with T2D who are overweight or obese. Recent data demonstrates that multidisciplinary approach to weight management in patients with T2D results in long-term weight loss and is associated with improved cardiovascular risk factors.20.