Major microbiota dysbiosis in severe obesity: fate after bariatric surgery

Calorie restriction on normal body weight mice prevents body weight regain on a follow-up high-fat diet by shaping an obesity-resistant-like gut microbiota profile

Calorie restriction (CR) is one of the most common approaches for obesity treatment, but whether resuming ad libitum feeding after CR in normal-weight mice can affect excessive weight regain remains poorly studied. To address this issue, male C57BL/6 mice were placed in three groups: a control group (n = 10), a group fed normal diet with 30% CR (n = 20); and a group fed a HF diet (n = 30). After four weeks, the CR group was fed either a normal diet (NDCR, n = 10) or a high-fat diet (HFCR, n = 10) for an additional eight weeks. At the end of the experiment, mice in the HF group ranked in the upper and lower thirds for weight gain were designated as obesity-prone (HFOP, n = 10) and obesity-resistant (HFOR, n = 10), respectively. CR delayed weight regain and visceral fat accumulation. Gut microbiota in the HFCR group were more similar to the HFOR group than the HFOP group, mainly due to reversion of the decreased level of Clostridiales induced by CR. Mediation analysis showed that Clostridiales may delay body weight regain by affecting the interconversion of succinate and fumarate. Random forest and structural equation analyses showed Christensenellaceae were the most important biomarker for alleviation of obesity. In conclusion, CR shapes an obesity-resistant-like gut microbiota profile that may attenuate body weight regain.

Risk assessment with gut microbiome and metabolite markers in NAFLD development

A growing body of evidence suggests interplay between the gut microbiota and the pathogenesis of nonalcoholic fatty liver disease (NAFLD). However, the role of the gut microbiome in early detection of NAFLD is unclear. Prospective studies are necessary for identifying reliable, microbiome markers for early NAFLD. We evaluated 2487 individuals in a community-based cohort who were followed up 4.6 years after initial clinical examination and biospecimen sampling. Metagenomic and metabolomic characterizations using stool and serum samples taken at baseline were performed for 90 participants who progressed to NAFLD and 90 controls who remained NAFLD free at the follow-up visit. Cases and controls were matched for gender, age, body mass index (BMI) at baseline and follow-up, and 4-year BMI change. Machine learning models integrating baseline microbial signatures (14 features) correctly classified participants (auROCs of 0.72 to 0.80) based on their NAFLD status and liver fat accumulation at the 4-year follow up, outperforming other prognostic clinical models (auROCs of 0.58 to 0.60). We confirmed the biological relevance of the microbiome features by testing their diagnostic ability in four external NAFLD case-control cohorts examined by biopsy or magnetic resonance spectroscopy, from Asia, Europe, and the United States. Our findings raise the possibility of using gut microbiota for early clinical warning of NAFLD development.

Obese Individuals With and Without Phlegm-Dampness Constitution Show Different Gut Microbial Composition Associated With Risk of Metabolic Disorders

Background

Obesity is conventionally considered a risk factor for multiple metabolic diseases, such as dyslipidemia, type 2 diabetes, hypertension, and cardiovascular disease (CVD). However, not every obese patient will progress to metabolic disease. Phlegm-dampness constitution (PDC), one of the nine TCM constitutions, is considered a high-risk factor for obesity and its complications. Alterations in the gut microbiota have been shown to drive the development and progression of obesity and metabolic disease, however, key microbial changes in obese patients with PDC have a higher risk for metabolic disorders remain elusive.

Methods

We carried out fecal 16S rRNA gene sequencing in the present study, including 30 obese subjects with PDC (PDC), 30 individuals without PDC (non-PDC), and 30 healthy controls with balanced constitution (BC). Metagenomic functional prediction of bacterial taxa was achieved using PICRUSt.

Results

Obese individuals with PDC had higher BMI, waist circumference, hip circumference, and altered composition of their gut microbiota compared to non-PDC obese individuals. At the phylum level, the gut microbiota was characterized by increased abundance of Bacteroidetes and decreased levels of Firmicutes and Firmicutes/Bacteroidetes ratio. At the genus level, Faecalibacterium, producing short-chain fatty acid, achieving anti-inflammatory effects and strengthening intestinal barrier functions, was depleted in the PDC group, instead, Prevotella was enriched. Most PDC-associated bacteria had a stronger correlation with clinical indicators of metabolic disorders rather than more severe obesity. The PICRUSt analysis demonstrated 70 significantly different microbiome community functions between the two groups, which were mainly involved in carbohydrate and amino acid metabolism, such as promoting Arachidonic acid metabolism, mineral absorption, and Lipopolysaccharide biosynthesis, reducing Arginine and proline metabolism, flavone and flavonol biosynthesis, Glycolysis/Gluconeogenesis, and primary bile acid biosynthesis. Furthermore, a disease classifier based on microbiota was constructed to accurately discriminate PDC individuals from all obese people.

Conclusion

Our study shows that obese individuals with PDC can be distinguished from non-PDC obese individuals based on gut microbial characteristics. The composition of the gut microbiome altered in obese with PDC may be responsible for their high risk of metabolic diseases.

Dietary macronutrients and the gut microbiome: a precision nutrition approach to improve cardiometabolic health

Accumulating evidence indicates that the gut microbiome is an important regulator of body weight, glucose and lipid metabolism, and inflammatory processes, and may thereby play a key role in the aetiology of obesity, insulin resistance and type 2 diabetes. Interindividual responsiveness to specific dietary interventions may be partially determined by differences in baseline gut microbiota composition and functionality between individuals with distinct metabolic phenotypes. However, the relationship between an individual's diet, gut microbiome and host metabolic phenotype is multidirectional and complex, yielding a challenge for practical implementation of targeted dietary guidelines. In this review, we discuss the latest research describing interactions between dietary composition, the gut microbiome and host metabolism. Furthermore, we describe how this knowledge can be integrated to develop precision-based nutritional strategies to improve bodyweight control and metabolic health in humans. Specifically, we will address that (1) insight in the role of the baseline gut microbial and metabolic phenotype in dietary intervention response may provide leads for precision-based nutritional strategies; that (2) the balance between carbohydrate and protein fermentation by the gut microbiota, as well as the site of fermentation in the colon, seems important determinants of host metabolism; and that (3) 'big data', including multiple omics and advanced modelling, are of undeniable importance in predicting (non-)response to dietary interventions. Clearly, detailed metabolic and microbial phenotyping in humans is necessary to better understand the link between diet, the gut microbiome and host metabolism, which is required to develop targeted dietary strategies and guidelines for different subgroups of the population.

Host-microbial interactions in metabolic diseases: from diet to immunity

Growing evidence suggests that the gut microbiome is an important contributor to metabolic diseases. Alterations in microbial communities are associated with changes in lipid metabolism, glucose homeostasis, intestinal barrier functions, and chronic inflammation, all of which can lead to metabolic disorders. Therefore, the gut microbiome may represent a novel therapeutic target for obesity, type 2 diabetes, and nonalcoholic fatty liver disease. This review discusses how gut microbes and their products affect metabolic diseases and outlines potential treatment approaches via manipulation of the gut microbiome. Increasing our understanding of the interactions between the gut microbiome and host metabolism may help restore the healthy symbiotic relationship between them.

Increasing the diversity of dietary fibers in a daily-consumed bread modifies gut microbiota and metabolic profile in subjects at cardiometabolic risk

Some cardiometabolic risk factors such as dyslipidemia and insulin resistance are known to be associated with low gut microbiota richness. A link between gut microbiota richness and the diversity of consumed dietary fibers (DF) has also been reported. We introduced a larger diversity of consumed DF by using a daily consumed bread in subjects at cardiometabolic risk and assessed the impacts on the composition and functions of gut microbiota as well as on cardiometabolic profile. Thirty-nine subjects at cardiometabolic risk were included in a double-blind, randomized, cross-over, twice 8-week study, and consumed daily 150 g of standard bread or enriched with a 7-dietary fiber mixture (5.55 g and 16.05 g of fibers, respectively). Before and after intervention, stool samples were collected for gut microbiota analysis from species determination down to gene-level abundance using shotgun metagenomics, and cardiometabolic profile was assessed. Multi-fiber bread consumption significantly decreased Bacteroides vulgatus, whereas it increased Parabacteroides distasonis, Fusicatenibacter saccharivorans, an unclassified Acutalibacteraceae and an unclassified Eisenbergiella (q < 0.1). The fraction of gut microbiota carrying the gene coding for five families/subfamilies of glycoside hydrolases (CAZymes) were also increased and negatively correlated with peaks and total/incremental area under curve (tAUC/iAUC) of postprandial glycemia and insulinemia. Compared to control bread, multi-fiber bread decreased total cholesterol (-0.42 mM; q < 0.01), LDL cholesterol (-0.36 mM; q < 0.01), insulin (-2.77 mIU/l; q < 0.05), and HOMA (-0.78; q < 0.05). In conclusion, increasing the diversity of DF in a daily consumed product modifies gut microbiota composition and function and could be a relevant nutritional tool to improve cardiometabolic profile.

Gut microbiota in bariatric surgery

Gut microbes share a symbiotic relationship with humans and perform several metabolic and physiological functions essential for human survival. It has been established in several scientific studies that obesity and other metabolic complications are always associated with disturbed gut microbiota profile, also called gut dysbiosis. In recent years, bariatric surgery has become a treatment of choice for weight loss, and it forms an important part of obesity management strategies across the globe. Interestingly, bariatric surgery has been shown to alter gut microbiota profile and synthesize short-chain fatty acids by gut microbes. In other words, gut microbes play a crucial role in better clinical outcomes associated with bariatric surgery. In addition, gut microbes are important in reducing weight and lowering the adverse events post-bariatric surgery. Therefore, several prebiotics, probiotics and postbiotics are recommended for patients who underwent bariatric surgery procedures for better clinical outcomes. The present review aims to understand the possible association between gut microbes and bariatric surgery and present scientific evidence showing the beneficial role of gut microbes in improving therapeutic outcomes of bariatric surgery.

Eco-Evolutionary Dynamics of the Human-Gut Microbiota Symbiosis in a Changing Nutritional Environment

The operational harmony between living beings and their circumstances, their ever-changing environment, is a constitutive condition of their existence. Nutrition and symbiosis are two essential aspects of this harmony. Disruption of the symbiosis between host and gut microbiota, the so-called dysbiosis, as well as the inadequate diet from which it results, contribute to the etiology of immunometabolic disorders. Research into the development of these diseases is highly influenced by our understanding of the evolutionary roots of metabolic functioning, thereby considering that chronic non-communicable diseases arise from an evolutionary mismatch. However, the lens has been mostly directed toward energy availability and metabolism, but away from our closest environmental factor, the gut microbiota. Thus, this paper proposes a narrative thread that places symbiosis in an evolutionary perspective, expanding the traditional framework of humans’ adaptation to their food environment.

Decoy bypass for appetite suppression in obese adults: role of synergistic nutrient sensing receptors GPR84 and FFAR4 on colonic endocrine cells

OBJECTIVE

Colonic enteroendocrine cells (EECs) store and release potent anorectic hormones that are key regulators of satiety. EECs express multiple nutrient sensing receptors, particularly for medium-chain fatty acids (MCFAs): GPR84 and FFAR4. Here we show a non-surgical approach with targeted colonic delivery of MCFA, which induces EEC and neuronal activation leading to anorectic effects.

DESIGN

A randomised, double-blind, placebo-controlled, cross-over study was performed in obese adults given combined GPR84 and FFAR4 agonists in colonic release capsules before meals. We measured serum hormones, energy intake and appetite perception. Cell type, activation by agonists and hormone/serotonin release were determined in human colonic explants. Mouse colonic afferent nerve responses to nutrients/mediators were recorded electrophysiologically.

RESULTS

Subjects receiving GPR84 and FFAR4 agonists had reduced overall calorific intake and increased postprandial levels of PYY versus placebo. Receptors including GPR84 and FFAR4 were coexpressed on human colonic EEC. Activation of GPR84 exclusively induced intracellular pERK, whereas FFAR4 selectively activated pCaMKII. Coactivation of GPR84 and FFAR4 induced both phosphoproteins, and superadditive release of GLP-1 and PYY. Nutrients and hormones convergently activated murine colonic afterent nerves via GLP-1, Y2 and 5-HT3 receptors.

CONCLUSIONS

Colonic GPR84 and FFAR4 agonists reduce energy intake and increase postprandial PYY in obese adults. Human colonic EECs coexpress these receptors, which activate cells via parallel intracellular pathways and synergistically evoke hormone release. Further synergism occurs in sensory nerve responses to MCFA and EEC mediators. Thus, synergistic activation of colonic endocrine cells via nutrient receptors is an important target for metabolic regulation.

TRAIL REGISTRATION NUMBER

NCT04292236.

The human gut microbiota contributes to type-2 diabetes non-resolution 5-years after Roux-en-Y gastric bypass

Roux-en-Y gastric bypass (RYGB) is efficient at inducing drastic albeit variable weight loss and type-2 diabetes (T2D) improvements in patients with severe obesity and T2D. We hypothesized a causal implication of the gut microbiota (GM) in these metabolic benefits, as RYGB is known to deeply impact its composition. In a cohort of 100 patients with baseline T2D who underwent RYGB and were followed for 5-years, we used a hierarchical clustering approach to stratify subjects based on the severity of their T2D (Severe vs Mild) throughout the follow-up. We identified via nanopore-based GM sequencing that the more severe cases of unresolved T2D were associated with a major increase of the class Bacteroidia, including 12 species comprising Phocaeicola dorei, Bacteroides fragilis, and Bacteroides caecimuris. A key observation is that patients who underwent major metabolic improvements do not harbor this enrichment in Bacteroidia, as those who presented mild cases of T2D at all times. In a separate group of 36 patients with similar baseline clinical characteristics and preoperative GM sequencing, we showed that this increase in Bacteroidia was already present at baseline in the most severe cases of T2D. To explore the causal relationship linking this enrichment in Bacteroidia and metabolic alterations, we selected 13 patients across T2D severity clusters at 5-years and performed fecal matter transplants in mice. Our results show that 14 weeks after the transplantations, mice colonized with the GM of Severe donors have impaired glucose tolerance and insulin sensitivity as compared to Mild-recipients, all in the absence of any difference in body weight and composition. GM sequencing of the recipient animals revealed that the hallmark T2D-severity associated bacterial features were transferred and were associated with the animals' metabolic alterations. Therefore, our results further establish the GM as a key contributor to long-term glucose metabolism improvements (or lack thereof) after RYGB.

Effects of caloric restriction on the gut microbiome are linked with immune senescence

BACKGROUND

Caloric restriction can delay the development of metabolic diseases ranging from insulin resistance to type 2 diabetes and is linked to both changes in the composition and metabolic function of the gut microbiota and immunological consequences. However, the interaction between dietary intake, the microbiome, and the immune system remains poorly described.

RESULTS

We transplanted the gut microbiota from an obese female before (AdLib) and after (CalRes) an 8-week very-low-calorie diet (800 kcal/day) into germ-free mice. We used 16S rRNA sequencing to evaluate taxa with differential abundance between the AdLib- and CalRes-microbiota recipients and single-cell multidimensional mass cytometry to define immune signatures in murine colon, liver, and spleen. Recipients of the CalRes sample exhibited overall higher alpha diversity and restructuring of the gut microbiota with decreased abundance of several microbial taxa (e.g., Clostridium ramosum, Hungatella hathewayi, Alistipi obesi). Transplantation of CalRes-microbiota into mice decreased their body fat accumulation and improved glucose tolerance compared to AdLib-microbiota recipients. Finally, the CalRes-associated microbiota reduced the levels of intestinal effector memory CD8+ T cells, intestinal memory B cells, and hepatic effector memory CD4+ and CD8+ T cells.

CONCLUSION

Caloric restriction shapes the gut microbiome which can improve metabolic health and may induce a shift towards the naïve T and B cell compartment and, thus, delay immune senescence. Understanding the role of the gut microbiome as mediator of beneficial effects of low calorie diets on inflammation and metabolism may enhance the development of new therapeutic treatment options for metabolic diseases.

TRIAL REGISTRATION

NCT01105143 , "Effects of negative energy balance on muscle mass regulation," registered 16 April 2010. Video Abstract.

Prebiotic to Improve Calcium Absorption in Postmenopausal Women After Gastric Bypass: A Randomized Controlled Trial

CONTEXT

The adverse skeletal effects of Roux-en-Y gastric bypass (RYGB) are partly caused by intestinal calcium absorption decline. Prebiotics, such as soluble corn fiber (SCF), augment colonic calcium absorption in healthy individuals.

OBJECTIVE

We tested the effects of SCF on fractional calcium absorption (FCA), biochemical parameters, and the fecal microbiome in a post-RYGB population.

METHODS

Randomized, double-blind, placebo-controlled trial of 20 postmenopausal women with history of RYGB a mean 5 years prior; a 2-month course of 20 g/day SCF or maltodextrin placebo was taken orally. The main outcome measure was between-group difference in absolute change in FCA (primary outcome) and was measured with a gold standard dual stable isotope method. Other measures included tolerability, adherence, serum calciotropic hormones and bone turnover markers, and fecal microbial composition via 16S rRNA gene sequencing.

RESULTS

Mean FCA ± SD at baseline was low at 5.5 ± 5.1%. Comparing SCF to placebo, there was no between-group difference in mean (95% CI) change in FCA (+3.4 [-6.7, +13.6]%), nor in calciotropic hormones or bone turnover markers. The SCF group had a wider variation in FCA change than placebo (SD 13.4% vs 7.0%). Those with greater change in microbial composition following SCF treatment had greater increase in FCA (r2 = 0.72, P = 0.05). SCF adherence was high, and gastrointestinal symptoms were similar between groups.

CONCLUSION

No between-group differences were observed in changes in FCA or calciotropic hormones, but wide CIs suggest a variable impact of SCF that may be due to the degree of gut microbiome alteration. Daily SCF consumption was well tolerated. Larger and longer-term studies are warranted.

Effects of Roux-en-Y Gastric Bypass Versus Sleeve Gastrectomy on Body Composition for Patients with a BMI > 35 kg/m2 at 1 Year After Surgery

PURPOSE

Effects of Roux-en-Y gastric bypass (RYGB) versus sleeve gastrectomy (SG) on body composition have not been well compared. This meta-analysis aimed to compare changes in fat mass (FM) and lean tissue mass (LTM) for patients with a BMI > 35 kg/m² at 1 year after RYGB and SG.

METHODS

PubMed, EMBASE, the Cochrane Library, and ClinicalTrials.gov were searched ending in December 2021 for eligible studies which reported baseline and postsurgical BMI, FM, and LTM.

RESULTS

Of 17 eligible studies, 831 patients were included, 484 following RYGB and 347 following SG. Weighted mean differences (WMD) and 95% confidence intervals (CI) were from a random-effects model. For patients with a BMI > 35 kg/m², RYGB resulted in a more substantial reduction of BMI (- 14.13 kg/m² [95%CI - 14.74, - 13.53] versus - 11.96 kg/m² [95%CI - 12.81, - 11.11], P < 0.001) and FM (- 26.22 kg [95%CI - 28.31, - 24.12] versus - 21.50 kg [95%CI - 25.52, - 17.48], P = 0.042) than SG, and a relatively weaker impact on LTM (- 8.28 kg [95%CI - 9.33, - 7.22] versus - 10.12 kg [95%CI - 11.55, - 8.68], P = 0.043).

CONCLUSION

This meta-analysis study indicates that RYGB is superior to SG in reducing excess FM for patients with a BMI > 35 kg/m² and seems to be more beneficial when LTM preservation is taken into consideration.

Compensatory intestinal antibody response against pro-inflammatory microbiota after bariatric surgery

Obesity and type 2 diabetes (T2D) are growing burdens for individuals and the health-care system. Bariatric surgery is an efficient, but drastic treatment to reduce body weight, normalize glucose values, and reduce low-grade inflammation. The gut microbiome, which is in part controlled by intestinal antibodies, such as IgA, is involved in the development of both conditions. Knowledge of the effect of bariatric surgery on systemic and intestinal antibody response is limited. Here, we determined the fecal antibody and gut microbiome response in 40 T2D and non-diabetic (ND) obese individuals that underwent bariatric surgery (N = 40). Body weight, fasting glucose concentrations and inflammatory parameters decreased after bariatric surgery, whereas pro-inflammatory bacterial species such as lipopolysaccharide (LPS), and flagellin increased in the feces. Simultaneously, concentrations of LPS- and flagellin-specific intestinal IgA levels increased with the majority of pro-inflammatory bacteria coated with IgA after surgery. Finally, serum antibodies decreased in both groups, along with a lower inflammatory tone. We conclude that intestinal rearrangement by bariatric surgery leads to expansion of typical pro-inflammatory bacteria, which may be compensated by an improved antibody response. Although further evidence and mechanistic insights are needed, we postulate that this apparent compensatory antibody response might help to reduce systemic inflammation by neutralizing intestinal immunogenic components and thereby enhance intestinal barrier function after bariatric surgery.

The association of weight loss with changes in the gut microbiota diversity, composition, and intestinal permeability: a systematic review and meta-analysis

The gut microbiome may be a mediator between obesity and health outcomes. However, it is unclear how intentional weight loss changes the gut microbiota and intestinal permeability. We aimed to systematically review and quantify this association. We searched Medline, Embase, CINAHL, Cochrane databases, and trial registries until June 2020 (PROSPERO: CRD42020205292). We included trials of weight loss interventions (energy-restricted diets, pharmacotherapy, bariatric surgery) reporting on the microbiome. Two reviewers independently completed screening, extraction, and risk assessment with the ROBINS-I tool. Pooled standardized mean differences (SMDs) were obtained from random-effects meta-analyses. Forty-seven trials with 1,916 participants (81% female) and a median follow-up of 6 months (range: 2-24) were included. Based on imprecise evidence but with fairly consistent direction of effect, weight loss was associated with a statistically significant increase in α-diversity [SMD: 0.4 (95% CI: 0.2, 0.6], p < .0001, I² = 70%, n = 30 studies) and a statistically significant reduction in intestinal permeability [SMD: -0.7 (95% CI: -0.9, -0.4), p < .0001, I² = 83%, n = 17 studies]. Each kg of weight loss was associated with a 0.012 (95% CI: 0.0003, 0.024, p = .045) increase in α-diversity and a -0.017 (95% CI: -0.034, -0.001, p = .038) reduction in intestinal permeability. There was clear evidence of increases in the relative abundance of Akkermansia, but no clear evidence of changes in individual phyla, species, or fecal short-chain fatty acids. Restricting the analyses to the studies with lower risk of bias did not materially alter the estimates. Increasing weight loss is positively associated with increases in gut microbiota α-diversity and reductions in intestinal permeability.

Microbiome and metabolome features of the cardiometabolic disease spectrum

Previous microbiome and metabolome analyses exploring non-communicable diseases have paid scant attention to major confounders of study outcomes, such as common, pre-morbid and co-morbid conditions, or polypharmacy. Here, in the context of ischemic heart disease (IHD), we used a study design that recapitulates disease initiation, escalation and response to treatment over time, mirroring a longitudinal study that would otherwise be difficult to perform given the protracted nature of IHD pathogenesis. We recruited 1,241 middle-aged Europeans, including healthy individuals, individuals with dysmetabolic morbidities (obesity and type 2 diabetes) but lacking overt IHD diagnosis and individuals with IHD at three distinct clinical stages—acute coronary syndrome, chronic IHD and IHD with heart failure—and characterized their phenome, gut metagenome and serum and urine metabolome. We found that about 75% of microbiome and metabolome features that distinguish individuals with IHD from healthy individuals after adjustment for effects of medication and lifestyle are present in individuals exhibiting dysmetabolism, suggesting that major alterations of the gut microbiome and metabolome might begin long before clinical onset of IHD. We further categorized microbiome and metabolome signatures related to prodromal dysmetabolism, specific to IHD in general or to each of its three subtypes or related to escalation or de-escalation of IHD. Discriminant analysis based on specific IHD microbiome and metabolome features could better differentiate individuals with IHD from healthy individuals or metabolically matched individuals as compared to the conventional risk markers, pointing to a pathophysiological relevance of these features.

By studying individuals along a spectrum of cardiometabolic disease and adjusting for effects of lifestyle and medication, this investigation identifies alterations of the metabolome and microbiome from dysmetabolic conditions, such as obesity and type 2 diabetes, to ischemic heart disease.

Metagenomics of the midgut microbiome of Rhipicephalus microplus from China

Background

Ticks, which are ectoparasites of animals, may carry multiple pathogens. The cattle tick Rhipicephalus microplus is an important bovine parasite in China. However, the midgut microbiome of R. microplus from China has not been characterized via metagenomic methods.

Methods

Rhipicephalus microplus were collected from cattle in the city of Changsha in Hunan province, China. The DNA of the midgut contents was extracted from fully engorged adult female R. microplus. A DNA library was constructed and sequenced using an Illumina HiSeq sequencing platform. SOAPdenovo software was used to assemble and analyze the clean data. The latent class analysis algorithm applied to system classification by MEGAN software was used to annotate the information on the species’ sequences. DIAMOND software was used to compare unigenes with the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, and functional annotation was carried out based on the results of the comparison.

Results

The dominant phyla in the five samples were Firmicutes, Proteobacteria, and Actinobacteria. Streptococcus, Mycobacterium, Anaplasma, Enterococcus, Shigella, Lactobacillus, Brachyspira, Pseudomonas, Enterobacter, Bacillus, and Lactococcus were the dominant genera in the five samples. The endosymbiotic bacterium Wolbachia was also detected in all of the samples. Mycobacterium malmesburyense, Streptococcus pneumoniae, Anaplasma phagocytophilum, Enterococcus faecium, Shigella sonnei, Enterococcus faecalis, Lactobacillus casei, Brachyspira hampsonii, Pseudomonas syringae, Enterobacter cloacae, and Lactococcus garvieae were the dominant species in the five samples. In addition to these bacterial species, we also detected some eukaryotes, such as Rhizophagus irregularis, Enterospora canceri, Smittium culicis, Zancudomyces culisetae, Trachipleistophora hominis, and viruses such as orf virus, human endogenous retrovirus type W, enzootic nasal tumor virus of goats, bovine retrovirus CH15, and galidia endogenous retrovirus in all of the samples at the species level. The results of the annotated KEGG pathway predictions for the gene functions of the midgut microflora of R. microplus indicated genes involved in lipid and amino acid metabolism, infectious diseases (e.g., Streptococcuspneumonia infection, human granulocytic anaplasmosis, Shigellasonnei infection, Salmonella enterica infection, and pathogenic Escherichia coli infection), and cancer.

Conclusions

Our study revealed that the midgut microbiome of R. microplus is not only composed of a large number of bacteria, but that a portion also comprises eukaryotes and viruses. The data presented here enhance our understanding of this tick’s midgut microbiome and provide fundamental information for the control of ticks and tick-borne diseases.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05161-6.

Circadian Rhythms, the Gut Microbiome, and Metabolic Disorders

The circadian clock and gut microbiome play integral roles in preserving metabolic homeostasis. Circadian rhythms represent an endogenous time-keeping system that regulates cell and organ functions and synchronizes physiology with external cues to establish metabolic homeostasis. A variety of functions throughout the gastrointestinal tract and liver are under circadian control, including nutrient transport, processing, and detoxification. The gut microbiota also plays an essential role in host metabolism, regulating processes such as digestion, inflammatory modulation, and bile acid metabolism. Both the circadian clock and the gut microbiota influence each other in a reciprocal fashion, as gut dysbiosis can precipitate circadian asynchrony, and vice-versa. Disruption of either system impacts homeostasis in a bidirectional manner and can contribute to metabolic dysfunction. Evidence suggests such disruptions can lead to the development of metabolic diseases, including obesity, diabetes, nonalcoholic fatty liver disease, cirrhosis, and hepatocellular carcinoma. This review will provide a basic overview of the circadian and gut microbial systems, how they are intertwined, and their impact on the liver and gastrointestinal tract and in the development of metabolic disease. Particular areas of discussion include epigenetic regulation of circadian pathways as well as a mechanistic overview of microbial dysbiosis. In addition, therapeutic targets of these systems, including dietary modifications, behavioral modifications, and microbial-directed therapies, will be explored.

Gut microbiota and vitamin status in persons with obesity: A key interplay

There are numerous factors involved in obesity progression and maintenance including systemic low-grade inflammation, adipose tissue dysfunction, or gut microbiota dysbiosis. Recently, a growing interest has arisen for vitamins' role in obesity and related disorders, both at the host and gut bacterial level. Indeed, vitamins are provided mostly by food, but some, from the B and K groups in particular, can be synthesized by the gut bacterial ecosystem and absorbed in the colon. Knowing that vitamin deficiency can alter many important cellular functions and lead to serious health issues, it is important to carefully monitor the vitamin status of patients with obesity and potentially already existing comorbidities as well as to examine the dysbiotic gut microbiota and thus potentially altered bacterial metabolism of vitamins. In this review, we examined both murine and human studies, to assess the prevalence of sub-optimal levels of several vitamins in obesity and metabolic alterations. This review also examines the relationship between vitamins and the gut microbiota in terms of vitamin production and the modulation of the gut bacterial ecosystem in conditions of vitamin shortage or supplementation. Furthermore, some strategies to improve vitamin status of patients with severe obesity are proposed within this review.

Gut microbiota and related metabolites in the pathogenesis of nonalcoholic steatohepatitis and its resolution after bariatric surgery

Nonalcoholic fatty liver disease (NAFLD) is increasing in parallel with the rising prevalence of obesity, leading to major health and socioeconomic consequences. To date, the most effective therapeutic approach for NAFLD is weight loss. Accordingly, bariatric surgery (BS), which produces marked reductions in body weight, is associated with significant histopathological improvements in advanced stages of NAFLD, such as nonalcoholic steatohepatitis (NASH) and liver fibrosis. BS is also associated with substantial taxonomical and functional alterations in gut microbiota, which are believed to play a significant role in metabolic improvement after BS. Interestingly, gut microbiota and related metabolites may be implicated in the pathogenesis of NAFLD through diverse mechanisms, including specific microbiome signatures, short chain fatty acid production or the modulation of one-carbon metabolism. Moreover, emerging evidence highlights the potential association between gut microbiota changes after BS and NASH resolution. In this review, we summarize the current knowledge on the relationship between NAFLD severity and gut microbiota, as well as the role of the gut microbiome and related metabolites in NAFLD improvement after BS.

Bariatric Surgery in NAFLD

Currently, there are no approved medications to treat patients with nonalcoholic steatohepatitis (NASH) with fibrosis or cirrhosis. Although the management goal in these patients is weight reduction by 7-10% with lifestyle modifications, only less than 10% of patients achieve this target at 1-year, and fewer maintain the weight loss at 5 years. Bariatric surgery is an option that may be considered in those who fail to lose weight by lifestyle changes. Bariatric surgery has been shown to improve liver histology including fibrosis secondary to NASH, in addition to other benefits including an improvement or resolution of type 2 diabetes mellitus, dyslipidemia, and hypertension, and a reduction of cardiovascular morbidity or mortality. There are no guidelines of bariatric surgery indications for the management of NASH. The purpose of this review is to critically appraise the current knowledge of the role of bariatric surgery and the potential mechanisms for its perceived benefits in the management of patients with NASH-related liver disease.

Dietary restriction in multiple sclerosis: evidence from preclinical and clinical studies

Dietary restriction (DR) interventions, which encompass both chronic and intermittent reductions in energy intake, are emerging as potential therapeutic approaches for dampening neuroinflammation and demyelination in multiple sclerosis (MS). Mechanisms mediating the beneficial effects of DR include the regulation of pro- and anti-inflammatory signalling molecules and gut microbiome remodelling. This article summarises the preclinical evidence supporting the role of DR in attenuating disease in animal models of MS and the developing clinical evidence indicating the safety and feasibility of such DR interventions in people with MS (pwMS).

Mechanisms of Weight Loss After Obesity Surgery

Obesity surgery remains the most effective treatment for obesity and its complications. Weight loss was initially attributed to decreased energy absorption from the gut but has since been linked to reduced appetitive behavior and potentially increased energy expenditure. Implicated mechanisms associating rearrangement of the gastrointestinal tract with these metabolic outcomes include central appetite control, release of gut peptides, change in microbiota, and bile acids. However, the exact combination and timing of signals remain largely unknown. In this review, we survey recent research investigating these mechanisms, and seek to provide insights on unanswered questions over how weight loss is achieved following bariatric surgery which may eventually lead to safer, nonsurgical weight-loss interventions or combinations of medications with surgery.

Lipocalin, Resistin and Gut Microbiota-Derived Propionate Could Be Used to Predict Metabolic Bariatric Surgery Selected Outcomes

Many patients with clinically severe obesity (CSO) need to undergo bariatric surgery, with possible side effects, so individualized predictive methods are required. Adipocytokines and gut/intestinal microbiota-derived metabolites could be predictive biomarkers of metabolic success post- surgery, but the knowledge in this field is undefined. The objective of this work was to determine whether adipocytokines and microbiota-derived metabolites can be used to predict the metabolic improvement post- surgery in women with CSO. We analyzed circulating levels of some cytokines and some microbiota-derived metabolites at baseline and 12 months post-surgery from 44 women with CSO and 21 women with normal weight. Results showed that glucose, insulin, glycosylated hemoglobin A1c (HbA1c), low-density lipoprotein (LDL-C), and triglycerides levels were decreased post-surgery, while high density lipoprotein increased. Twelve months later, leptin, resistin, lipocalin, PAI-1, TNF-α, and IL-1β levels were lower than baseline, meanwhile adiponectin, IL-8, and IL-10 levels were increased. Moreover, baseline lipocalin levels were associated with HbA1c reduction post-surgery; meanwhile baseline resistin was related to postoperative HOMA2 (insulin resistance) and baseline propionate was associated with LDL-C decrease. To conclude, the detection of lipocalin, resistin, and propionate levels may be used to predict the metabolic success following bariatric surgery, although new knowledge is needed.

Novel Insight into the Mechanism of Metabolic Surgery Causing the Diversity in Glycemic Status in Type 2 Diabetes

Metabolic surgery results in diverse glycemic status in patients with type 2 diabetes (T2D), including hyperglycemia without remission, significant amelioration of hyperglycemia with partial remission, complete restoration of euglycemia, or with prolonged remission, hyperglycemia recurrence in relapses after remission, or post-bariatric hypoglycemia. Unfortunately, it is not known how metabolic surgery leads to this diverse consequence. Here, we discuss the diversity of glycemic status associated with metabolic surgery and the potential mechanisms of T2D remission. We also highlight the relationship between the change in low-grade inflammation and T2D remission after metabolic surgery. We hypothesize that the level of inflammatory and anti-inflammatory cytokines controls the efficacy of metabolic surgery in patients with T2D. This hypothesis may provide further insight into the mechanism of the beneficial effects of metabolic surgery patients with T2D.

Altered Glucose Metabolism and Glucose Transporters in Systemic Organs After Bariatric Surgery

The Roux-en-Y gastric bypass (RYGB) is highly effective in the remission of obesity and associated diabetes. The mechanisms underlying obesity and type 2 diabetes mellitus remission after RYGB remain unclear. This study aimed to evaluate the changes in continuous dynamic FDG uptake patterns after RYGB and examine the correlation between glucose metabolism and its transporters in variable endocrine organs using ¹⁸F-fluoro-2-deoxyglucose positron emission tomography images. Increased glucose metabolism in specific organs, such as the small intestine and various fat tissues, is closely associated with improved glycemic control after RYGB. In Otsuka Long-Evans Tokushima Fatty rats fed with high-fat diets, RYGB operation increases intestine glucose transporter expression and various fat tissues' glucose transporters, which are not affected by insulin. The fasting glucose decrement was significantly associated with RYGB, sustained weight loss, post-RYGB oral glucose tolerance test (OGTT) area under the curve (AUC), glucose transporter, or glycolytic enzymes in the small bowel and various fat tissues. High intestinal glucose metabolism and white adipose tissue-dependent glucose metabolism correlated with metabolic benefit after RYGB. These findings suggest that the newly developed glucose biodistribution accompanied by increased glucose transporters is a mechanism associated with the systemic effect of RYGB.

Obesity and Responsiveness to Food Marketing Before and After Bariatric Surgery

Although food marketing is often accused of increasing population obesity, the relationship between individual responsiveness to marketing and obesity has yet to be established: Are people with obesity more responsive to food marketing and, if so, is it a stable trait or can it be reversed by bariatric surgery? We studied the responses to three common marketing tactics that frame foods and portions as healthier than they really are in three groups of women: (a) a group of patients with obesity before, 3 months, and 12 months after bariatric surgery, (b) a control group of lean women, and (c) another control group of women with obesity but not seeking any treatment for their obesity. People with obesity were initially more responsive to food marketing, but bariatric surgery reduced their responsiveness down to the level of lean people. In addition to documenting another potential psychological consequence of bariatric surgery, our study suggests that the higher responsiveness of people with obesity is not a stable individual predisposition and supports the notion of a reciprocal relationship between obesity and sensitivity to environmental influences.

The Main Anthocyanin Monomer from Lycium ruthenicum Murray Fruit Mediates Obesity via Modulating the Gut Microbiota and Improving the Intestinal Barrier

Anthocyanins have been shown to exert certain antiobesity properties, but the specific relationship between anthocyanin-induced beneficial effects and the gut microbiota remains unclear. Petunidin-3-O-[rhamnopyranosyl-(trans-p-coumaroyl)]-5-O-(β-D-glucopyranoside) (P3G) is the main anthocyanin monomer from the fruit of Lycium ruthenicum Murray. Therefore, in this study, we investigated the antiobesity and remodeling effects of P3G on gut microbiota through a high-fat diet (HFD)-induced obesity mouse model and a fecal microbiota transplantation experiment. P3G was found to reduce body weight gain, fat accumulation, and liver steatosis in HFD-induced obese mice. Moreover, supplementation with P3G alleviated the HFD-induced imbalance in gut microbiota composition, and transferring the P3G-regulated gut microbiota to recipient mice provided comparable protection against obesity. This is the first time evidence is provided that P3G has an antiobesity effect by changing the intestinal microbiota. Our present data highlight a link between P3G intervention and enhancement in gut barrier integrity. This may be a promising option for obesity prevention.

The Role of the Gut Microbiota in the Development and Progression of Major Depressive and Bipolar Disorder

A growing number of studies in rodents indicate a connection between the intestinal microbiota and the brain, but comprehensive human data is scarce. Here, we systematically reviewed human studies examining the connection between the intestinal microbiota and major depressive and bipolar disorder. In this review we discuss various changes in bacterial abundance, particularly on low taxonomic levels, in terms of a connection with the pathophysiology of major depressive and bipolar disorder, their use as a diagnostic and treatment response parameter, their health-promoting potential, as well as novel adjunctive treatment options. The diversity of the intestinal microbiota is mostly decreased in depressed subjects. A consistent elevation of phylum Actinobacteria, family Bifidobacteriaceae, and genus Bacteroides, and a reduction of family Ruminococcaceae, genus Faecalibacterium, and genus Roseburia was reported. Probiotics containing Bifidobacterium and/or Lactobacillus spp. seemed to improve depressive symptoms, and novel approaches with different probiotics and synbiotics showed promising results. Comparing twin studies, we report here that already with an elevated risk of developing depression, microbial changes towards a “depression-like” microbiota were found. Overall, these findings highlight the importance of the microbiota and the necessity for a better understanding of its changes contributing to depressive symptoms, potentially leading to new approaches to alleviate depressive symptoms via alterations of the gut microbiota.

Metaproteomics Approach and Pathway Modulation in Obesity and Diabetes: A Narrative Review

Low-grade inflammatory diseases revealed metabolic perturbations that have been linked to various phenotypes, including gut microbiota dysbiosis. In the last decade, metaproteomics has been used to investigate protein composition profiles at specific steps and in specific healthy/pathologic conditions. We applied a rigorous protocol that relied on PRISMA guidelines and filtering criteria to obtain an exhaustive study selection that finally resulted in a group of 10 studies, based on metaproteomics and that aim at investigating obesity and diabetes. This batch of studies was used to discuss specific microbial and human metaproteome alterations and metabolic patterns in subjects affected by diabetes (T1D and T2D) and obesity. We provided the main up- and down-regulated protein patterns in the inspected pathologies. Despite the available results, the evident paucity of metaproteomic data is to be considered as a limiting factor in drawing objective considerations. To date, ad hoc prepared metaproteomic databases collecting pathologic data and related metadata, together with standardized analysis protocols, are required to increase our knowledge on these widespread pathologies.

Characterization of the Gut Microbiota in Individuals with Overweight or Obesity during a Real-World Weight Loss Dietary Program: A Focus on the Bacteroides 2 Enterotype

Background: Dietary intervention is a cornerstone of weight loss therapies. In obesity, a dysbiotic gut microbiota (GM) is characterized by high levels of Bacteroides lineages and low diversity. We examined the GM composition changes, including the Bacteroides 2 enterotype (Bact2), in a real-world weight loss study in subjects following a high-protein hypocaloric diet with or without a live microorganisms (LMP) supplement. Method: 263 volunteers were part of this real-world weight loss program. The first phase was a high-protein low-carbohydrate calorie restriction diet with or without LMP supplements. Fecal samples were obtained at baseline and after 10% weight loss for 163 subjects. Metagenomic profiling was obtained by shotgun sequencing. Results: At baseline, the Bact2 enterotype was more prevalent in subjects with aggravated obesity and metabolic alterations. After weight loss, diversity increased and Bact2 prevalence decreased in subjects with lower GM diversity at baseline, notably in LMP consumers. Significant increases in Akkermansia muciniphila and Parabacteroides distasonis and significant decreases of Eubacterium rectale, Streptococcus thermophilus and Bifidobacterial lineages were observed after weight loss. Conclusions: Baseline microbiome composition is associated with differential changes in GM diversity and Bact2 enterotype prevalence after weight loss. Examining these signatures could drive future personalized nutrition efforts towards more favorable microbiome compositions.

Correlation between Gut Microbiota, its Metabolic Products, and their Association with Liver Enzymes among Sample of Egyptian Females

Background and Aim: The gut microbiota appears to play a critical role in the pathogenesis of obesity, liver metabolism and the associated diseases. The present study aimed to identify the existing gut microbiota enterotypes and its metabolic products profiles among a sample of normal weight and obese Egyptian females, and to investigate the correlation between gut microbiota; body mass index andliver enzymes among them.Methods: A case-control cross-sectional study, included 112 Egyptian females; 82obese and30 normal weight; with age ranged from 25 up to 60 years. For each participant, anthropometric measurements (weight, height and BMI), laboratory investigations (AST, ALT, SCFA, CRP) and microbiota analysis were done. Results: The obese females had higher significant values of CRP,AST, ALTand SCFA. In addition, obese females had insignificant higher values of log Bacteroidetes, log firmicutes, log firmicutes/ Bacteroidetes ratio, and log lactobacillus, and insignificant lower values of log bifidobacteria; than normal weight group.Among normal weight group, Lactobacillus shad significant positive correlations with SCFA, Bifidobacteria and Firmicutes, and significant negative correlations with AST, ALTand CRP. Bifidobacteria had significant negative correlations with Ht and ALT. Bacteroidetes bacteria had significant positive correlations with SCFA, and significant negative correlations with age and height. Firmicutes bacteria had significant negative correlations with AST and ALT. Firmicutes / Bacteroidetes Ratio had significant negative correlations with AST, ALTand SCFA. Among obese group, Lactobacillus and Bifidobacteria had significant negative correlations with Firmicutes / Bacteroidetes Ratio however; these correlations were insignificant among normal weight group. Moreover, there were insignificant correlations between any type of studied microbiota and any of the anthropometric or laboratory parameters; except Firmicutes bacteria had significant negative correlations with ALT.Conclusion: The beneficial Lactobacillus and bifidobacteria have its good impact in improving obesity status, liver function in form of ALT.

Potential Role of Akkermansia muciniphila in Parkinson's Disease and Other Neurological/Autoimmune Diseases

The composition of the gut microbiota, including Akkermansia muciniphila (A. muciniphila), is altered in many neurological diseases and may be involved in the pathophysiological processes of Parkinson's disease (PD). A. muciniphila, a mucin-degrading bacterium, is a potential next-generation microbe that has anti-inflammatory properties and is responsible for keeping the body healthy. As the role of A. muciniphila in PD has become increasingly apparent, we discuss the potential link between A. muciniphila and various neurological diseases (including PD) in the current review.

Shifts in gut microbiota and their metabolites induced by bariatric surgery. Impact of factors shaping gut microbiota on bariatric surgery outcomes

Evidence suggests that bariatric surgery alters gut microbiota, although its impact at compositional and functional level is not well described. In this review, the most relevant findings, mainly described in Roux-en-Y gastric bypass and sleeve gastrectomy, are outlined. Although the number of studies has increased in the last years, conclusive assertions cannot be elaborated. An issue to address is to know the influence of these alterations on host metabolism and the contribution of gut microbiota derived metabolites. New lines of research have been focusing on analysing gut microbiota functionality rather than evaluating changes at compositional level, and the functions of gut microbiota metabolites in host metabolism, what will bring more relevant information about the influence of gut microbiota in bariatric surgery outcomes. Personalized medicine, because of the predictive value of gut microbiota, is another promising field. The possibility of a specific gut microbiota pattern that could predict type 2 diabetes remission or weight loss failure after bariatric surgery is a matter of great interest. However, little is known about how gut microbiota manipulation could contribute to the beneficial effects of bariatric surgery. Peri-operative antibiotics prophylaxis or probiotic supplementation early after surgery, are strategies barely studied so far, and could constitute a novel tool in the management of weight loss and metabolic profile improvement after surgery.

Effects of obesity and weight-loss surgery shift the microbiome and impact alloimmune responses

PURPOSE OF REVIEW

Obesity is a worldwide health problem with increasing rates in both children and adults. Bariatric surgery (BS) represents the only effective long-term treatment. Beneficial effects of BS may be mediated through shifts of the gut microbiome. Here, we introduce data linking the microbiome to alloimmune responses.

RECENT FINDINGS

The rapid development of microbiome sequencing technologies in addition to the availability of gnotobiotic facilities have enabled mechanistic investigations on modulations of alloimmune responses through microbiomes. BS has been shown to improve comorbidities and chronic inflammation caused by obesity. Changes in microbiota and microbiota-related metabolites may play a role. Patients either listed or having received a transplant have undergone weight loss surgery, thus allowing to dissect mechanisms of microbial shifts to alloimmunity.

SUMMARY

Weight loss and BS have the potential to improve transplant outcomes by ameliorating alloimmune responses. Those effects may be carried out through alterations of the gut microbiome.

High-throughput mediation analysis of human proteome and metabolome identifies mediators of post-bariatric surgical diabetes control

To improve the power of mediation in high-throughput studies, here we introduce High-throughput mediation analysis (Hitman), which accounts for direction of mediation and applies empirical Bayesian linear modeling. We apply Hitman in a retrospective, exploratory analysis of the SLIMM-T2D clinical trial in which participants with type 2 diabetes were randomized to Roux-en-Y gastric bypass (RYGB) or nonsurgical diabetes/weight management, and fasting plasma proteome and metabolome were assayed up to 3 years. RYGB caused greater improvement in HbA1c, which was mediated by growth hormone receptor (GHR). GHR's mediation is more significant than clinical mediators, including BMI. GHR decreases at 3 months postoperatively alongside increased insulin-like growth factor binding proteins IGFBP1/BP2; plasma GH increased at 1 year. Experimental validation indicates (1) hepatic GHR expression decreases in post-bariatric rats; (2) GHR knockdown in primary hepatocytes decreases gluconeogenic gene expression and glucose production. Thus, RYGB may induce resistance to diabetogenic effects of GH signaling.Trial Registration: Clinicaltrials.gov NCT01073020.

Efficacy and Mechanisms of Gastric Volume-Restriction Bariatric Devices

Obesity is a chronic disease that affects over 795 million people worldwide. Bariatric surgery is an effective therapy to combat the epidemic of clinically severe obesity, but it is only performed in a very small proportion of patients because of the limited surgical indications, the irreversibility of the procedure, and the potential postoperative complications. As an alternative to bariatric surgery, numerous medical devices have been developed for the treatment of morbid obesity and obesity-related disorders. Most devices target restriction of the stomach, but the mechanism of action is likely more than just mechanical restriction. The objective of this review is to integrate the underlying mechanisms of gastric restrictive bariatric devices in obesity and comorbidities. We call attention to the need for future studies on potential mechanisms to shed light on how current gastric volume-restriction bariatric devices function and how future devices and treatments can be further improved to combat the epidemic of obesity.

Spot-light on microbiota in obesity and cancer

Over the last few years, the complexity and diversity of gut microbiota within and across individuals has been detailed in relation to human health. Further, understanding of the bidirectional association between gut microbiota and metabolic disorders has highlighted a complimentary, yet crucial role for microbiota in the onset and progression of obesity-related cancers. While strategies for cancer prevention and cure are known to work efficiently when supported by healthy diet and lifestyle choices and physical activity, emerging evidence suggests that the complex interplay relating microbiota both to neoplastic and metabolic diseases could aid strategies for cancer treatment and outcomes. This review will explore the experimental and clinical grounds supporting the functional role of gut microbiota in the pathophysiology and progression of cancers in relation to obesity and its metabolic correlates. Therapeutic approaches aiding microbiota restoration in connection with cancer treatments will be discussed.

Obesity Management and Chronic Kidney Disease

Obesity is one of the risk factors for the development and progression of chronic kidney disease (CKD). Several studies have shown the association between increased body mass index and kidney function decline. Obesity leads to CKD directly by acting as an independent risk factor and indirectly through increasing risks for diabetes, hypertension, and atherosclerosis, a group of well-established independent risk factors for CKD. Alterations in renal hemodynamics, inflammation, and in hormones and growth factors results in hyperfiltration injury and focal segmental glomerulosclerosis. In recent years, many studies have shown that the gut microbiome may play a role in the pathogenesis of obesity. Dysbiosis has been noted in obese subjects in both human and animal studies. Changes in the gut microbiome in obese patients promote weight gain by effectively extracting energy from diet, and induction of low-grade inflammation. Evidence also points to the role of inflammation within the adipose tissue in obesity as a key factor in the pathogenesis of obesity-related complications. Thus, obesity is the net result of complex interactions between behavioral, genetic, and environmental factors. In terms of management, conservative approaches are often the first option, but they often are unsuccessful in achieving and/or maintaining weight loss, particularly in severe obesity. Consequently, nonmedical management with bariatric surgery is the most effective treatment option for morbid obesity and has shown mitigation of multiple risk factors for the progression of CKD. The most frequently performed interventions are vertical sleeve gastrectomy and Roux-en-Y gastric bypass. Studies have shown that bariatric surgery is associated with beneficial effects on CKD by mitigating its risk factors by weight loss, reducing insulin resistance, hemoglobin A1c, and proteinuria, in addition to positive long-term outcomes. Because of the epidemic of obesity, the prevalence of obesity in kidney transplant recipients also is increasing. The maximal body mass index (BMI) threshold for kidney transplantation is not clear. The Organ Procurement Transplant Network/Scientific Registry of Transplant Recipients 2019 annual data report showed that the proportion of kidney transplant recipient candidates with a BMI of 30 kg/m² or greater is increasing steadily. Morbid obesity is linked to adverse graft outcomes including delayed graft function, primary nonfunction, and decreased graft survival. Obesity is also an independent risk factor for cardiovascular death in kidney transplant recipients, suggesting that these patients should not be excluded from transplantation based on their BMI because transplantation is associated with lower mortality compared with dialysis. However, many centers exclude obese patients (with different BMI cut-off values) from transplantation to avoid postoperative complications. To minimize the surgical complications of kidney transplantation in obese patients, our center has adopted the robot-assisted kidney transplantation procedure. Our data show that this approach is comparable with historical nonobese controls in the United Network for Organ Sharing database in terms of patient and graft survival. Another surgical option for this group of patients at our center is a combined robotic sleeve gastrectomy and robotic-assisted kidney transplant. In a recent study, this approach showed promising results in terms of weight loss, patient survival, and graft survival, and might become more common in the future.

Alterations in Faecal Metagenomics and Serum Metabolomics Indicate Management Strategies for Patients With Budd-Chiari Syndrome

We investigated the effects of gut microbiota and serum metabolite levels in patients with Budd-Chiari syndrome (B-CS) and their importance for guiding clinical management strategies. In total, 214 B-CS patients (93 untreated and 121 treated) and 41 healthy controls were enrolled. Gut microbiota and serum metabolome were analysed using shotgun metagenomics and liquid chromatography-mass spectrometry. The gut microbiota of the patients showed abundance of Campylobacter and low levels of Saccharomyces, Deinococcus, and Thiomonas (P < 0.05). Thirty metabolites, including taurocholate and (R)-3-hydroxybutyric acid, were identified in the patients (VIP > 1, P < 0.05 and FC > 1.2 or FC < 0.83). Random forest (RF) models showed that serum metabolome could effectively identify B-CS from healthy controls and RF-metabolomics exhibited perfect discrimination (AUC = 100%, 95% CI: 100% - 100%), which was significantly higher than that achieved by RF-metagenomics (AUC = 58.48%, 95% CI: 38.46% - 78.5%). Campylobacter concisus and taurocholate showed significant positive correlation in patients with clinical manifestations (P < 0.05). Actinobacteria levels were significantly higher in untreated patients than in treated patients (P < 0.05). Campylobacter and Veillonella levels were significantly higher in treated patients than in healthy controls (P < 0.05). We identified major alterations in the gut microbiota and serum metabolome of patients with B-CS. Faecal metagenomics- and serum metabolomics-guided management strategies are required for patients with B-CS.

ARE ENTEROTYPES IN OBESE MODIFIED BY BARIATRIC SURGERY, THE USE OF PROBIOTIC SUPPLEMENTS AND FOOD HABITS?

INTRODUCTION

Studies suggest that bariatric surgery, use of probiotic supplements and the dietary pattern can change enterotypes, as well as the entire microbial population.

OBJECTIVE

To verify the influence of bariatric surgery, the use of probiotic supplements and eating habits on enterotypes in obese patients.

METHODS

Articles published between the 2015 and 2020 were searched in Lilacs and PubMed with the headings: probiotics, eating behavior, food consumption, food, diet, microbiota, gastrointestinal microbiome, bariatric surgery, gastric bypass and the keyword enterotype in Portuguese, English and Spanish.

RESULTS

Of the 260 articles found, only studies carried out in obese adults relating changes in the enterotype after bariatric surgery or use of probiotics or dietary patterns and original articles were selected. In the end, eight papers on enterotype change and bariatric surgery were selected and categorized, four on the relationship between food consumption and microbiota and one on the effects of probiotics on enterotypes.

CONCLUSION

The microbial structure is widely modified after bariatric surgery, since the use of probiotic supplement does not bring lasting changes. Enterotypes appear to be shaped by long-term dietary patterns, can modulate how nutrients are metabolized and can be a useful biomarker to improve clinical management.

A pilot study about the development and characterization of a Roux en Y gastric bypass model in obese Yucatan minipigs

Performing the Roux-en-Y gastric bypass (RYGBP) in obese Yucatan minipigs provides an opportunity to explore the mechanisms behind the effects of this surgery in controlled environmental and nutritional conditions. We hypothesized that RYGBP in these minipigs would induce changes at multiple levels, as in obese humans. We sought to characterize RYGBP in a diet-induced obese minipig model, compared with a pair-fed sham group. After inducing obesity with an ad libitum high-fat/high-sugar diet, we performed RYGBP (n = 7) or sham surgery (n = 6). Oral glucose tolerance tests (OGTT) were performed before and after surgery. Histological analyses were conducted to compare the alimentary limb at sacrifice with tissue sampled during RYGBP surgery. One death occurred in the RYGBP group at postoperative day (POD) 3. Before sacrifice, weight loss was the same across groups. GLP-1 secretion (OGTT) was significantly higher at 15, 30 and 60 min at POD 7, and at 30 and 60 min at POD 30 in the RYGBP group. Incremental insulin area under the curve increased significantly after RYGBP (p = 0.02). RYGBP induced extensive remodeling of the alimentary limb. Results show that RYGBP can be safely performed in obese minipigs, and changes mimic those observed in humans.

Exploring Semi-Quantitative Metagenomic Studies Using Oxford Nanopore Sequencing: A Computational and Experimental Protocol

The gut microbiome plays a major role in chronic diseases, of which several are characterized by an altered composition and diversity of bacterial communities. Large-scale sequencing projects allowed for characterizing the perturbations of these communities. However, translating these discoveries into clinical applications remains a challenge. To facilitate routine implementation of microbiome profiling in clinical settings, portable, real-time, and low-cost sequencing technologies are needed. Here, we propose a computational and experimental protocol for whole-genome semi-quantitative metagenomic studies of human gut microbiome with Oxford Nanopore sequencing technology (ONT) that could be applied to other microbial ecosystems. We developed a bioinformatics protocol to analyze ONT sequences taxonomically and functionally and optimized preanalytic protocols, including stool collection and DNA extraction methods to maximize read length. This is a critical parameter for the sequence alignment and classification. Our protocol was evaluated using simulations of metagenomic communities, which reflect naturally occurring compositional variations. Next, we validated both protocols using stool samples from a bariatric surgery cohort, sequenced with ONT, Illumina, and SOLiD technologies. Results revealed similar diversity and microbial composition profiles. This protocol can be implemented in a clinical or research setting, bringing rapid personalized whole-genome profiling of target microbiome species.

The Impact of Bariatric Surgery Versus Non-Surgical Treatment on Blood Pressure: Systematic Review and Meta-Analysis

The purpose of this study was to compare bariatric surgery versus non-surgical treatment on blood pressure for patients with obesity. Nineteen RCTs (1353 total patients) were included. In the pooled analyses, bariatric surgery reduces more systolic blood pressure (WMD: - 3.937 mmHg, CI95%: - 6.000 to - 1.875, p < 0.001, I² = 0%), diastolic blood pressure (WMD: - 2.690 mmHg, CI95%: - 3.994 to - 1.385, P < 0.001, I² = 0%) and more antihypertensives. In subgroup analyses, patients after Roux-en-Y gastric bypass, with poor control of hypertension (BP > 130/80 mmHg) and diabetes mellitus (HbA1C > 7.0%, FPG > 7.0 mmol/L), elder patients (> 45 years), non-severe obesity (BMI < 40 kg/cm², body weight < 120 kg), less waist circumference (< 115 cm) tend to decrease more blood pressure. Besides, patients after surgery also lost more weight (p < 0.001), decreased more waist circumference (p < 0.001), fasting plasma glucose (p < 0.001), glycosylated hemoglobin (p < 0.001), triglycerides (p < 0.001), hsCRP (p = 0.001), increased more high-density lipoprotein cholesterol (p < 0.001), and had better remission of metabolic syndrome (p < 0.001). Changes in total cholesterol, low-density lipoprotein cholesterol, renal function, resting heart rate, and 6-min walking test were not significantly different. Therefore, bariatric surgery is more effective than non-surgical treatment in controlling patients' blood pressure.

Factors associated with inflamm-aging in institutionalized older people

The increase in inflammatory cytokines associated with a reduction in the bioavailability of zinc has been used as a marker for inflammation. Despite the high inflammatory state found in institutionalized older individuals, few studies have proposed verifying the factors associated with this condition in this population. To verify the factors associated with inflamm-aging in institutionalized older people. A total of 178 older people (≥ 60 years old) living in nursing homes in Natal/RN were included in the study. Cluster analysis was used to identify three groups according to their inflammatory state. Analysis anthropometric, biochemical, sociodemographic, and health-related variables was carried out. In sequence, an ordinal logistic regression was performed for a confidence level of 95% in those variables with p < 0.20 in the bivariate analysis. IL-6, TNF-α, zinc, low-density lipids (LDL), high-density lipids (HDL), and triglycerides were associated with inflamm-aging. The increase of 1 unit of measurement of LDL, HDL, and triglycerides increased the chance of inflammation-aging by 1.5%, 4.1%, and 0.9%, respectively, while the oldest old (≥ 80 years old) had an 84.9% chance of presenting inflamm-aging in relation to non-long-lived older people (< 80 years). The association between biochemical markers and inflamm-aging demonstrates a relationship between endothelial injury and the inflammatory state. In addition, the presence of a greater amount of fat in the blood may present a higher relative risk of death.

Regular intake of energy drinks and multivitamin supplements is associated with elevated plasma vitamin B6 levels in post-bariatric patients

The aim of the present survey was to analyze plasma vitamin B6 levels in post-bariatric patients and to elucidate the causal factors associated with elevated plasma vitamin B6 levels. This is a retrospective analysis of electronic patient data of all post-bariatric patients evaluated at the endocrine outpatient clinic of the University Hospital Basel in 2017, for which plasma vitamin B6 values were assessed during regular follow-up visits. In total, 205 patients were included in the study, whereof a minority of 43% had vitamin B6 levels in the normal range. 50% of the patients had vitamin B6 levels up to fourfold higher than the upper normal limit and 7% had levels more than fourfold above the upper normal limit. Vitamin B6 deficiency was not observed in any patient. While multivitamin supplementation in general was associated with elevated plasma vitamin B6 levels, the highest vitamin B6 levels were found after biliopancreatic diversion (BPD) and in patients who reported daily energy drink intake. Elevated plasma vitamin B6 levels up to fourfold above the upper normal limit are common in postbariatric patients and are associated with regular multivitamin supplementation, while highly elevated plasma vitamin B6 levels were seen primarily upon regular energy drink intake. Thus, a regular follow-up of vitamin B6 plasma levels and critical evaluation of vitamin B6 supplementation, either as part of the multivitamin preparation or related to regular energy drink intake, is highly warranted and should be an integral part of the routine post-bariatric follow-up.

Gut Microbiota in Adipose Tissue Dysfunction Induced Cardiovascular Disease: Role as a Metabolic Organ

The gut microbiome has emerged as a key regulator of host metabolism. Accumulating evidence has indicated that the gut microbiota is involved in the development of various human diseases. This association relies on the structure and metabolites of the gut microbiota. The gut microbiota metabolizes the diet ingested by the host into a series of metabolites, including short chain fatty acids, secondary bile acids, trimethylamine N-oxide, and branched-chain amino acids, which affects the physiological processes of the host by activating numerous signaling pathways. In this review, we first summarize the various mechanisms through which the gut microbiota influences adipose tissue dysfunction and metabolic processes that subsequently cause cardiovascular diseases, highlighting the complex interactions between gut microbes, their metabolites, and the metabolic activity of the host. Furthermore, we investigated the current status of clinical therapies for adipose tissue dysfunction directed at the gut microbiota. Finally, we discuss the challenges that remain to be addressed before this field of research can be translated to everyday clinical practice.

Synbiotics Containing Nanoprebiotics: A Novel Therapeutic Strategy to Restore Gut Dysbiosis

A new formulation, nanoprebiotics [e.g., phthalyl pullulan nanoparticles (PPNs)], was demonstrated to enhance the antimicrobial activity of probiotics [e.g., Lactobacillus plantarum (LP)] in vitro through intracellular stimulation better than that by backbone prebiotics, which are commonly used. In this study, we aimed to investigate whether this combination would exert distinct effects as synbiotics in vivo. Synbiotics combinations of LP, pullulan, and PPNs were used as experimental treatments in a dysbiosis-induced murine model, and their restorative effect was assessed using pathogen Escherichia coli K99 challenge. Our results showed that the E. coli infection was suppressed markedly in the experimental group fed with synbiotics containing PPNs. In addition, the decrease in serum endotoxin level after synbiotics treatment suggested the reinforcement of the gut barrier. Comparison of treatment groups, including a normal control group, showed that synbiotics containing PPNs increased microbial diversity, which is a representative parameter of healthy status. Furthermore, distinct from probiotics treatment alone, synbiotics showed additive effects of enrichment of several well-known beneficial bacteria such as Lactobacillus, Bifidobacterium, and other butyrate-producing bacteria including Faecalibacterium. Collectively, our results indicate that synbiotics containing PPNs are effective at restoring gut dysbiosis, suppressing pathogenic infection, and increasing microbial diversity, suggesting that synbiotics with nanoprebiotics have the potential to be a novel strategy for ameliorating gut dysbiosis and infectious diseases.

Intestinal alteration of α-gustducin and sweet taste signaling pathway in metabolic diseases is partly rescued after weight loss and diabetes remission

Carbohydrates and sweeteners are detected by the sweet taste receptor in enteroendocrine cells (EECs). This receptor is coupled to the gustducin G-protein, which α-subunit is encoded by GNAT3 gene. In intestine, the activation of sweet taste receptor triggers a signaling pathway leading to GLP-1 secretion, an incretin hormone. In metabolic diseases, GLP-1 concentration and incretin effect are reduced while partly restored after Roux-en-Y gastric bypass (RYGB). We wondered if the decreased GLP-1 secretion in metabolic diseases is caused by an intestinal defect in sweet taste transduction pathway. In our RNA-sequencing of EECs, GNAT3 expression is decreased in patients with obesity and type 2 diabetes compared with normoglycemic obese patients. This prompted us to explore sweet taste signaling pathway in mice with metabolic deteriorations. During obesity onset in mice, Gnat3 expression was downregulated in EECs. After metabolic improvement with enterogastro anastomosis surgery in mice (a surrogate of the RYGB in humans), the expression of Gnat3 increased in the new alimentary tract and glucose-induced GLP-1 secretion was improved. To evaluate if high-fat diet-induced dysbiotic intestinal microbiota could explain the changes in the expression of sweet taste α-subunit G-protein, we performed a fecal microbiota transfer in mice. However, we could not conclude if dysbiotic microbiota impacted or not intestinal Gnat3 expression. Our data highlight that metabolic disorders were associated with altered gene expression of sweet taste signaling in intestine. This could contribute to impaired GLP-1 secretion that is partly rescued after metabolic improvement.NEW & NOTEWORTHY Our data highlighted 1) the sweet taste transduction pathway in EECs plays pivotal role for glucose homeostasis at least at gene expression level; 2) metabolic disorders lead to altered gene expression of sweet taste signaling pathway in intestine contributing to impaired GLP-1 secretion; and 3) after surgical intestinal modifications, increased expression of GNAT3, encoding α-gustducin contributed to metabolic improvement.