Role of Presurgical Gut Microbial Diversity in Roux-en-Y Gastric Bypass Weight-Loss Response: A Cohort Study

INTRODUCTION

Roux-en-Y gastric bypass (RYGB) substantially alters the gut microbial composition which could be associated with the metabolic improvements seen after surgery. Few studies have been conducted in Latin American populations, such as Mexico, where obesity prevalence is above 30% in the adult population. Thus, the aim of this study was to characterize the changes in the gut microbiota structure in a Mexican cohort before and after RYGB and to explore whether surgery-related changes in the microbial community were associated with weight loss.

METHODS

Biological samples from patients who underwent RYGB were examined before and 12 months after surgery. Fecal microbiota characterization was performed through 16S rRNA sequencing.

RESULTS

Twenty patients who underwent RYGB showed a median excess weight loss of 66.8% 12 months after surgery. Surgery increased alpha diversity estimates (Chao, Shannon index, and observed operational taxonomic units, p < 0.05) and significantly altered gut microbiota composition. Abundance of four genera was significantly increased after surgery: Oscillospira, Veillonella, Streptococcus, and an unclassified genus from Enterobacteriaceae family (PFDR < 0.1). The change in Veillonella abundance was associated with lower excess weight loss (rho = -0.446, p = 0.063) and its abundance post-surgery with a greater BMI (rho = 0.732, p = 5.4 × 10-4). In subjects without type 2 diabetes, lower bacterial richness and diversity before surgery were associated with a greater Veillonella increase after surgery (p < 0.05), suggesting that a lower bacterial richness before surgery could favor the bloom of certain oral-derived bacteria that could negatively impact weight loss.

CONCLUSION

Presurgical microbiota profile may favor certain bacterial changes associated with less successful results.

Gut Microbiota Contribution to Weight-Independent Glycemic Improvements after Gastric Bypass Surgery

Roux-en-Y gastric bypass surgery (RYGB) leads to improved glycemic control in individuals with severe obesity beyond the effects of weight loss alone. Here, We addressed the potential contribution of gut microbiota in mediating this favourable surgical outcome by using an established preclinical model of RYGB. 16S rRNA sequencing revealed that RYGB-treated Zucker fatty rats had altered fecal composition of various bacteria at the phylum and species levels, including lower fecal abundance of an unidentified Erysipelotrichaceae species, compared with both sham-operated (Sham) and body weight-matched to RYGB-treated (BWM) rats. Correlation analysis further revealed that fecal abundance of this unidentified Erysipelotrichaceae species linked with multiple indices of glycemic control uniquely in RYGB-treated rats. Sequence alignment of this Erysipelotrichaceae species identified Longibaculum muris to be the most closely related species, and its fecal abundance positively correlated with oral glucose intolerance in RYGB-treated rats. In fecal microbiota transplant experiments, the improved oral glucose tolerance of RYGB-treated compared with BWM rats could partially be transferred to recipient germfree mice, independently of body weight. Unexpectedly, providing L. muris as a supplement to RYGB recipient mice further improved oral glucose tolerance, while administering L. muris alone to chow-fed or Western style diet-challenged conventionally raised mice had minimal metabolic impact. Taken together, our findings provide evidence that the gut microbiota contributes to weight loss-independent improvements in glycemic control after RYGB and demonstrate how correlation of a specific gut microbiota species with a host metabolic trait does not imply causation. IMPORTANCE Metabolic surgery remains the most effective treatment modality for severe obesity and its comorbidities, including type 2 diabetes. Roux-en-Y gastric bypass (RYGB) is a commonly performed type of metabolic surgery that reconfigures gastrointestinal anatomy and profoundly remodels the gut microbiota. While it is clear that RYGB is superior to dieting when it comes to improving glycemic control, the extent to which the gut microbiota contributes to this effect remains untested. In the present study, we uniquely linked fecal Erysipelotrichaceae species, including Longibaculum muris, with indices of glycemic control after RYGB in genetically obese and glucose-intolerant rats. We further show that the weight loss-independent improvements in glycemic control in RYGB-treated rats can be transmitted via their gut microbiota to germfree mice. Our findings provide rare causal evidence that the gut microbiota contributes to the health benefits of metabolic surgery and have implications for the development of gut microbiota-based treatments for type 2 diabetes.

The Effects of One Anastomosis Gastric Bypass Surgery on the Gastrointestinal Tract

One anastomosis gastric bypass (OAGB) is an emerging bariatric procedure, yet data on its effect on the gastrointestinal tract are lacking. This study sought to evaluate the incidence of small-intestinal bacterial overgrowth (SIBO) following OAGB; explore its effect on nutritional, gastrointestinal, and weight outcomes; and assess post-OABG occurrence of pancreatic exocrine insufficiency (PEI) and altered gut microbiota composition. A prospective pilot cohort study of patients who underwent primary-OAGB surgery is here reported. The pre-surgical and 6-months-post-surgery measurements included anthropometrics, glucose breath-tests, biochemical tests, gastrointestinal symptoms, quality-of-life, dietary intake, and fecal sample collection. Thirty-two patients (50% females, 44.5 ± 12.3 years) participated in this study, and 29 attended the 6-month follow-up visit. The mean excess weight loss at 6 months post-OAGB was 67.8 ± 21.2%. The glucose breath-test was negative in all pre-surgery and positive in 37.0% at 6 months (p = 0.004). Positive glucose breath-test was associated with lower reported dietary intake and folate levels and higher vitamin A deficiency rates (p ≤ 0.036). Fecal elastase-1 test (FE1) was negative for all pre-surgery and positive in 26.1% at 6 months (p = 0.500). Both alpha and beta diversity decreased at 6 months post-surgery compared to pre-surgery (p ≤ 0.026). Relatively high incidences of SIBO and PEI were observed at 6 months post-OAGB, which may explain some gastrointestinal symptoms and nutritional deficiencies.

Gut Microbiota and Mycobiota Evolution Is Linked to Memory Improvement after Bariatric Surgery in Obese Patients: A Pilot Study

Patients with obesity are known to exhibit gut microbiota dysbiosis and memory deficits. Bariatric surgery (BS) is currently the most efficient anti-obesity treatment and may improve both gut dysbiosis and cognition. However, no study has investigated association between changes of gut microbiota and cognitive function after BS. We prospectively evaluated 13 obese patients on anthropometric data, memory functions, and gut microbiota-mycobiota before and six months after BS. The Rey Auditory Verbal Learning Test (AVLT) and the symbol span (SS) of the Weschler Memory Scale were used to assess verbal and working memory, respectively. Fecal microbiota and mycobiota were longitudinally analyzed by 16S and ITS2 rRNA sequencing respectively. AVLT and SS scores were significantly improved after BS (AVLT scores: 9.7 ± 1.7 vs. 11.2 ± 1.9, p = 0.02, and SS scores: 9.7 ± 23.0 vs. 11.6 ± 2.9, p = 0.05). An increase in bacterial alpha-diversity, and Ruminococcaceae, Prevotella, Agaricus, Rhodotorula, Dipodascus, Malassezia, and Mucor were significantly associated with AVLT score improvement after BS, while an increase in Prevotella and a decrease in Clostridium, Akkermansia,&nbsp;Dipodascus and Candida were linked to SS scores improvement. We identified several changes in the microbial communities that differ according to the improvement of either the verbal or working memories, suggesting a complex gut-brain-axis that evolves after BS.

Long-Term Effects of Bariatric Surgery on Gut Microbiota Composition and Faecal Metabolome Related to Obesity Remission

Obesity is one of the main worldwide public health concerns whose clinical management demands new therapeutic approaches. Bariatric surgery is the most efficient treatment when other therapies have previously failed. Due to the role of gut microbiota in obesity development, the knowledge of the link between bariatric surgery and gut microbiota could elucidate new mechanistic approaches. This study aims to evaluate the long-term effects of bariatric surgery in the faecal metagenome and metabolome of patients with severe obesity. Faecal and blood samples were collected before and four years after the intervention from patients with severe obesity. Biochemical, metagenomic and metabolomic analyses were performed and faecal short-chain fatty acids were measured. Bariatric surgery improved the obesity-related status of patients and significantly reshaped gut microbiota composition. Moreover, this procedure was associated with a specific metabolome profile characterized by a reduction in energetic and amino acid metabolism. Acetate, butyrate and propionate showed a significant reduction with bariatric surgery. Finally, correlation analysis suggested the existence of a long-term compositional and functional gut microbiota profile associated with the intervention. In conclusion, bariatric surgery triggered long-lasting effects on gut microbiota composition and faecal metabolome that could be associated with the remission of obesity.

A microbial signature following bariatric surgery is robustly consistent across multiple cohorts

Bariatric surgery induces significant shifts in the gut microbiota which could potentially contribute to weight loss and metabolic benefits. The aim of this study was to characterize a microbial signature following Roux-en-Y Gastric bypass (RYGB) surgery using novel and existing gut microbiota sequence data. We generated 16S rRNA gene and metagenomic sequences from fecal samples from patients undergoing RYGB surgery (n = 61 for 16S rRNA gene and n = 135 for metagenomics) at pre-surgical baseline and one, six, and twelve-month post-surgery. We compared these data with three smaller publicly available 16S rRNA gene and one metagenomic datasets from patients who also underwent RYGB surgery. Linear mixed models and machine learning approaches were used to examine the presence of a common microbial signature across studies. Comparison of our new sequences with previous longitudinal studies revealed strikingly similar profiles in both fecal microbiota composition (r = 0.41 ± 0.10; p < .05) and metabolic pathways (r = 0.70 ± 0.05; p < .001) early after surgery across multiple datasets. Notably, Veillonella, Streptococcus, Gemella, Fusobacterium, Escherichia/Shigella, and Akkermansia increased after surgery, while Blautia decreased. Machine learning approaches revealed that the replicable gut microbiota signature associated with RYGB surgery could be used to discriminate pre- and post-surgical samples. Opportunistic pathogen abundance also increased post-surgery in a consistent manner across cohorts. Our study reveals a robust microbial signature involving many commensal and pathogenic taxa and metabolic pathways early after RYGB surgery across different studies and sites. Characterization of the effects of this robust microbial signature on outcomes of bariatric surgery could provide insights into the development of microbiome-based interventions for predicting or improving outcomes following surgery.

Immunometabolism, Micronutrients, and Bariatric Surgery: The Use of Transcriptomics and Microbiota-Targeted Therapies

BACKGROUND

Obesity is associated with the gut microbiota and decreased micronutrient status. Bariatric surgery is a recommended therapy for obesity. It can positively affect the composition of the gut bacteria but also disrupt absorption of nutrients. Low levels of micronutrients can affect metabolic processes, like glycolysis, TCA cycle, and oxidative phosphorylation, that are associated with the immune system also known as immunometabolism.

METHODS

MEDLINE, PUBMED, and Google Scholar were searched. Articles involving gut microbiome, micronutrient deficiency, gut-targeted therapies, transcriptome analysis, micronutrient supplementation, and bariatric surgery were included.

RESULTS

Studies show that micronutrients play a pivotal role in the intestinal immune system and regulating immunometabolism. Research demonstrates that gut-targeting therapies may improve the microbiome health for bariatric surgery populations. There is limited research that examines the role of micronutrients in modulating the gut microbiota among the bariatric surgery population.

CONCLUSIONS

Investigations are needed to understand the influence that micronutrient deficiencies have on the gut, particularly immunometabolism. Nutritional transcriptomics shows great potential in providing this type of analysis to develop gut-modulating therapies as well as more personalized nutrition recommendations for bariatric surgery patients.

Gut Microbiota, Probiotics and Psychological States and Behaviors after Bariatric Surgery-A Systematic Review of Their Interrelation

The gastrointestinal (GI) microbiota plays an important role in health and disease, including brain function and behavior. Bariatric surgery (BS) has been reported to result in various changes in the GI microbiota, therefore demanding the investigation of the impact of GI microbiota on treatment success. The goal of this systematic review was to assess the effects of BS on the microbiota composition in humans and other vertebrates, whether probiotics influence postoperative health, and whether microbiota and psychological and behavioral factors interact. A search was conducted using PubMed and Web of Science to find relevant studies with respect to the GI microbiota and probiotics after BS, and later screened for psychological and behavioral parameters. Studies were classified into groups and subgroups to provide a clear overview of the outcomes. Microbiota changes were further assessed for whether they were specific to BS in humans through the comparison to sham operated controls in other vertebrate studies. Changes in alpha diversity appear not to be specific, whereas dissimilarity in overall microbial community structure, and increases in the abundance of the phylum Proteobacteria and Akkermansia spp. within the phylum Verrucomicrobia after surgery were observed in both human and other vertebrates studies and may be specific to BS in humans. Human probiotic studies differed regarding probiotic strains and dosages, however it appeared that probiotic interventions were not superior to a placebo for quality of life scores or weight loss after BS. The relationship between GI microbiota and psychological diseases in this context is unclear due to insufficient available data.

Roux-en-Y gastric bypass surgery changes fungal and bacterial microbiota in morbidly obese patients-A pilot study

The Roux-en-Y gastric bypass (RYGB) remains the most effective treatment for morbidly obese patients to lower body weight and improve glycemic control. There is recent evidence that the mycobiome (fungal microbiome) can aggravate disease severity in a number of diseases including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) and hepatitis; moreover, a dysbiotic fungal microbiota has been reported in the obese. We characterized fungal and bacterial microbial composition in fecal samples of 16 morbidly obese patients before and three months after RYGB surgery and compared with nine healthy controls. We found that RYGB surgery induced a clear alteration in structure and composition of the gut fungal and bacterial microbiota. Beta diversity analysis revealed significant differences in bacterial microbiota between obese patients before surgery and healthy controls (P < 0.005) and a significant, unidirectional shift in RYGB patients after surgery (P < 0.001 vs. before surgery). In contrast, there was no significant difference in fungal microbiota between groups but individually specific changes after RYGB surgery. Interestingly, RYGB surgery induced a significant reduction in fungal alpha diversity namely Chao1, Sobs, and Shannon diversity index (P<0.05, respectively) which contrasts the trend for uniform changes in bacteria towards increased richness and diversity post-surgery. We did not observe any inter-kingdom relations in RYGB patients but in the healthy control cohort and there were several correlations between fungi and bacteria and clinical parameters (P<0.05, respectively) that warrant further research. Our study identifies changes in intestinal fungal communities in RYGB patients that are distinct to changes in the bacterial microbiota.

The Role of the Gut Microbiota in Sustained Weight Loss Following Roux-en-Y Gastric Bypass Surgery

BACKGROUND

The aim of the study was to investigate the role of the gut microbiota in weight regain or suboptimal weight loss following Roux-en-Y gastric bypass (RYGB).

MATERIALS AND METHODS

The gut microbiota composition in post-RYGB patients who experienced successful weight loss (SWL, n = 6), post-RYGB patients who experienced poor weight loss (PWL, n = 6), and non-surgical controls (NSC, n = 6) who were age- and BMI-matched to the SWL group (NSC, n = 6) were characterized through 16S rRNA gene sequencing. To further investigate the impact of the gut microbiota on weight profile, human fecal samples were transplanted into antibiotic-treated mice.

RESULTS

Orders of Micrococcales and Lactobacillales were enriched in SWL and PWL groups compared to the NSC group. No significant difference was observed in the gut microbiota composition between PWL and SWL patients. However, transfer of the gut microbiota from human patients into antibiotic-treated mice resulted in significantly greater weight gain in PWL recipient mice compared to SWL recipient mice. A few genera that were effectively transferred from humans to mice were associated with weight gain in mice. Among them, Barnesiella was significantly higher in PWL recipient mice compared to SWL and NSC recipient mice.

CONCLUSION

These results indicate that the gut microbiota are at least functionally, if not compositionally, different between PWL and SWL patients. Some taxa may contribute to weight gain after surgery. Future studies will need to determine the molecular mechanisms behind the effects of the gut bacteria on weight regain after RYGB.

Gut Microbiota Imbalance Can Be Associated with Non-malabsorptive Small Bowel Shortening Regardless of Blind Loop

INTRODUCTION

Some traditional bariatric surgery procedures may lead to functional gut shortening, which may unsettle the fine-tuned gastrointestinal physiology and affect gut microbiota balance.

PURPOSE

Evaluate the gut microbiota behavior in rat models facing gut shortening due to intestinal bypass.

MATERIALS AND METHODS

Wistar rats (n = 17) were randomly distributed in three groups: (1) sham group (n = 5); (2) blind loop group (n = 6); and (3) resection group (n = 6). Intestinal samples and feces were analyzed to measure bacterial concentrations (small intestinal bacterial overgrowth-SIBO) 12 weeks after the experimental procedures. Bacterial translocation (BT) was investigated in the mesenteric lymph node (MLN), liver, spleen, and lung of the animals. In addition, inflammatory aspects were investigated in their liver and small bowel through histological analysis.

RESULTS

Regardless of blind loop, gut shortening groups recorded similar high level of bacterial concentrations in intestine compartments, greater than that of the sham group (p ≤ 0.05). BT was only observed in the MLN of gut shortening models, with higher percentage in the blind loop group (p ≤ 0.05). The gut and liver histopathological analysis showed similar low-grade chronic inflammation in both gut shortening groups, likely associated with SIBO/BT events.

CONCLUSION

Sustained SIBO/BT was associated with proximal gut shortening in half regardless of blind loop, whereas the GI tract's ability to restore gut microbiota balance after a surgical challenge on the small bowel appears to be linked to the functional remaining gut.

Akkermansia muciniphila abundance is lower in severe obesity, but its increased level after bariatric surgery is not associated with metabolic health improvement

The gut bacterial species Akkermansia muciniphila is associated with a healthier clinical profile. The purpose of this study was to determine the association between A. muciniphila and glucose homeostasis in patients undergoing bariatric surgery (BS): gastric banding (GB) or Roux-en-Y gastric bypass (RYGB). This nonrandomized prospective study included 65 women with severe obesity. Longitudinal analysis included subjects for whom A. muciniphila data were available at follow-up [1, 3, and 12 mo; GB (n = 10) or RYGB (n = 11)]. Glucose homeostasis markers were measured under fasting conditions (glucose, insulin, and HbA1c) or during an oral glucose tolerance test. Fecal microbiota was analyzed using shotgun metagenomics, and A. muciniphila relative abundance was assessed with 16S rRNA quantitative PCR. A. muciniphila relative abundance was significantly lower in severe obesity [mean body mass index, 45.7 kg/m² (SD 5.4)] than in moderate obesity [33.2 kg/m² (SD 3.8)] but not associated with glucose homeostasis markers. A significant increase in A. muciniphila relative abundance after RYGB was not correlated with metabolic improvement. Baseline A. muciniphila abundance was correlated with bacterial gene richness and was highest in the high-richness Ruminococcaceae enterotype. A. muciniphila increased in relative abundance after BS in patients with low baseline A. muciniphila abundance, especially those with a Bacteroides type 2 enterotype classification. Although decreased in severe obesity, relative abundance of A. muciniphila was not associated with glucose homeostasis before or after BS. A certain level of A. muciniphila abundance might be required to observe a beneficial link to health. The severity of obesity and gut dysbiosis may partly explain the discrepancy with previous findings in less obese populations.

Changes in the intestinal microbiota of superobese patients after bariatric surgery

OBJECTIVES

The gut microbiota is associated with obesity and weight loss after bariatric surgery and has been related to its changing pattern. Exactly how the bacterial population affects weight loss and the results of surgery remain controversial. This study aimed to evaluate the intestinal microbiota of superobese patients before and after gastric bypass surgery (RYGB).

METHOD

DNA fragments for the microbiota obtained from stool samples collected from nine superobese patients before and after bariatric surgery were sequenced using Ion Torrent.

RESULTS

We observed that with a mean follow-up of 15 months, patients achieved 55.9% excess weight loss (EWL). A significant population reduction in the Proteobacteria phylum (11 to 2%, p=0.0025) was observed after surgery, while no difference was seen in Firmicutes and Bacteroidetes. Further analyses performed with two specific individuals with divergent clinical outcomes showed a change in the pattern between them, with a significant increase in Firmicutes and a decrease in Bacteroidetes in the patient with less weight loss (%EWL 50.79 vs. 61.85).

CONCLUSIONS

RYGB affects the microbiota of superobese patients, with a significant reduction in Proteobacteria in patients with different weight loss, showing that different bacteria may contribute to the process.

Draft Genome and Description of Eisenbergiella massiliensis Strain AT11T: A New Species Isolated from Human Feces After Bariatric Surgery

A novel strain of a Gram-stain negative, non-motile, non-spore forming rod-shaped, obligate anaerobic bacterium, designated AT11^T, was isolated from a stool sample of a morbidly obese woman living in Marseille, France. This bacterium was characterized using biochemical, chemotaxonomic, and phylogenetic methods. The 16S rRNA gene sequence analysis showed that strain AT11^T had a 97.8% nucleotide sequence similarity with Eisenbergiella tayi strain B086562^T, the closest species with standing in nomenclature. The major cellular fatty acids of the novel isolate were C_16:0 followed by saturated or unsaturated C₁₈ fatty acids (C_18:1n9, C_18:1n5 and C_18:0). The draft genome of strain AT11^T is 7,114,554 bp long with 48% G+C content. 6176 genes were predicted, including 6114 protein-coding genes and 62 were RNAs (with 2 5S rRNA genes, two 16S rRNA genes, two 23S rRNA genes, and 56 tRNA genes). The digital DNA-DNA hybridization (dDDH) relatedness between the new isolate and E. tayi strain B086562^T was 23.1% ± 2.2. Based on the phenotypic, chemotaxonomic, genomic, and phylogenetic characteristics, Eisenbergiella massiliensis sp. nov., is proposed. The type strain is AT11^T (= DSM 100838^T = CSUR P2478^T).

Gut Microbiota Interacts with Markers of Adipose Tissue Browning, Insulin Action and Plasma Acetate in Morbid Obesity

SCOPE

To examine the potential relationship among gene expression markers of adipose tissue browning, gut microbiota, and insulin sensitivity in humans.

METHODS AND RESULTS

Gut microbiota composition and gene markers of browning are analyzed in subcutaneous (SAT) and visceral (VAT) adipose tissue from morbidly obese subjects (n = 34). Plasma acetate is measured through 1 H NMR and insulin sensitivity using euglycemic hyperinsulinemic clamp. Subjects with insulin resistance show an increase in the relative abundance (RA) of the phyla Bacteroidetes and Proteobacteria while RA of Firmicutes is decreased. In all subjects, Firmicutes RA is negatively correlated with HbA1c and fasting triglycerides, whereas Proteobacteria RA was negatively correlated with insulin sensitivity. Firmicutes RA is positively associated with markers of brown adipocytes (PRDM16, UCP1, and DIO2) in SAT, but not in VAT. Multivariate regression analysis indicates that Firmicutes RA contributes significantly to SAT PRDM16, UCP1, and DIO2 mRNA variance after controlling for age, BMI, HbA1c , or insulin sensitivity. Interestingly, Firmicutes RA, specifically those bacteria belonging to the Ruminococcaceae family, is positively associated with plasma acetate levels, which are also linked to SAT PRDM16 mRNA and insulin sensitivity.

CONCLUSION

Gut microbiota composition is linked to adipose tissue browning and insulin action in morbidly obese subjects, possibly through circulating acetate.

Bile acids and bariatric surgery

Bariatric surgery, specifically Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG), are the most effective and durable treatments for morbid obesity and potentially a viable treatment for type 2 diabetes (T2D). The resolution rate of T2D following these procedures is between 40 and 80% and far surpasses that achieved by medical management alone. The molecular basis for this improvement is not entirely understood, but has been attributed in part to the altered enterohepatic circulation of bile acids. In this review we highlight how bile acids potentially contribute to improved lipid and glucose homeostasis, insulin sensitivity and energy expenditure after these procedures. The impact of altered bile acid levels in enterohepatic circulation is also associated with changes in gut microflora, which may further contribute to some of these beneficial effects. We highlight the beneficial effects of experimental surgical procedures in rodents that alter bile secretory flow without gastric restriction or altering nutrient flow. This information suggests a role for bile acids beyond dietary fat emulsification in altering whole body glucose and lipid metabolism strongly, and also suggests emerging roles for the activation of the bile acid receptors farnesoid x receptor (FXR) and G-protein coupled bile acid receptor (TGR5) in these improvements. The limitations of rodent studies and the current state of our understanding is reviewed and the potential effects of bile acids mediating the short- and long-term metabolic improvements after bariatric surgery is critically examined.

The Role of Morbid Obesity in the Promotion of Metabolic Disruptions and Non-Alcoholic Steatohepatitis by Helicobacter Pylori

Background

Helicobacter pylory (HP) infection has been associated to an increased rate of type 2 diabetes (T2D) and liver disease through its effect on insulin resistance and systemic inflammation. However, results are inconstant and no studies exist in morbidly obese patients, in which both insulin resistance and inflammation coexist.

Material and Methods

Cross-sectional study to evaluate the relationship between HP infection and alterations in carbohydrate metabolism, lipid profile, inflammation markers, and liver disease in patients awaiting for bariatric surgery. HP infection was histologically assessed in gastric antrum biopsy from 416 subjects. Liver biopsy was also available in 93 subjects.

Results

Both impaired fasting glucose and T2D were similar when comparing subjects with and without HP infection (24.2% vs. 22%, p = 0.290 and 29.4% vs. 29.1%, p = 0.916, respectively), with no differences between groups in the HOMA-IR, lipid profile neither inflammatory parameters. However, HP infection was higher among subjects with a BMI ≥ 40.0 kg/m² in comparison with lower degrees of obesity (71.7% vs. 60.0%, p = 0.041). In addition, subjects without HP infection showed higher degrees of steatosis (44.1±26.4% vs. 32.0±20.7%, p = 0.038), as well as a lower prevalence of non-alcoholic steatohepatitis (9.3% vs. 30.7%, p = 0.023).

Conclusions

In patients with morbid obesity, HP infection does not seem to be associated with abnormal carbohydrate metabolism. In addition, less advanced degrees of non-alcoholic fatty disease were observed. We suggest that low-grade inflammation that accompanies obesity mitigates the diabetogenic effect of HP, so the presence of obesity should be considered in studies that evaluate the HP metabolic effects.

Role of Gut Microbiota in the Aetiology of Obesity: Proposed Mechanisms and Review of the Literature

The aetiology of obesity has been attributed to several factors (environmental, dietary, lifestyle, host, and genetic factors); however none of these fully explain the increase in the prevalence of obesity worldwide. Gut microbiota located at the interface of host and environment in the gut are a new area of research being explored to explain the excess accumulation of energy in obese individuals and may be a potential target for therapeutic manipulation to reduce host energy storage. Several mechanisms have been suggested to explain the role of gut microbiota in the aetiology of obesity such as short chain fatty acid production, stimulation of hormones, chronic low-grade inflammation, lipoprotein and bile acid metabolism, and increased endocannabinoid receptor system tone. However, evidence from animal and human studies clearly indicates controversies in determining the cause or effect relationship between the gut microbiota and obesity. Metagenomics based studies indicate that functionality rather than the composition of gut microbiota may be important. Further mechanistic studies controlling for environmental and epigenetic factors are therefore required to help unravel obesity pathogenesis.

Sleeve gastrectomy leads to Helicobacter pylori eradication

BACKGROUND

The role of Helicobacter pylori (HP) in patients scheduled and undergoing laparoscopic sleeve gastrectomy (LSG) has not been previously evaluated.

METHODS

Included were obese patients presenting to our institution for LSG over 24 months. All patients had presurgical HP breath test, and the symptomatic ones received triple therapy with symptom follow-up. Post surgery, all excluded stomachs were evaluated for HP, and those that were positive performed a second 13C-urea breath test (UBT) 3 months later.

RESULTS

Forty patients underwent LSG. Male to female sex ratio was 1:3; mean age-42 years; mean weight-122 kg; and mean BMI of 43.4 kg/m2. Presurgical HP was positive in 15 (37.5%) patients (11 symptomatic and four asymptomatic). Only these 11 patients were given HP eradication therapy and all experienced complete subsequent symptom resolution. HP was detected in 17 out of the 40 (42.5%) cases of excluded stomachs. All performed a 13C-UBT 3 months post operation and only three (17.6%) tested positive.

CONCLUSIONS

HP infection is frequent in biopsies from patients with previous LSG and the majority of follow-up 13C-UBT were negative. In our small initial sample, we treated only symptomatic patients preoperatively. Routine screening for HP for all LSG patients and/or treatment for all positive ones would subject patients to expensive and unnecessary investigations. We propose that this stomach-reducing, pylorus-preserving surgery might even lead to HP eradication. The clinical implications of HP and this gastrectomy for a non-neoplastic, non-peptic indication deserve further study.

Microbial flora of the stomach after gastric bypass for morbid obesity

BACKGROUND

The normal stomach is virtually sterile but the effect of Roux-en-Y gastric bypass (RYGBP) on bacterial flora in the used (very small proximal pouch) and unused (large bypassed) gastric chambers is not known. In a prospective study, this variable was documented.

METHODS

Bariatric subjects (n=37) were submitted to endoscopic examination of both gastric reservoirs via FUJINON enteroscope model EN-450P5, 7.3 +/- 1.4 years after RYGBP. Age was 42.4 +/- 9.9 years (70.2% females), preoperative BMI was 53.5 +/- 10.6, and current BMI was 32.6 +/- 7.8 kg/m2. Methods included quantitative culture of gastric secretion along with gastric pH and lactulose/hydrogen breath test.

RESULTS

None of the subjects displayed diarrhea, malabsorption or other complaints suggestive of GI bacterial overgrowth. Elevated counts of bacteria and fungi were identified in both chambers, with predominance of aerobes and anaerobes, but not molds and yeasts, in the proximal stomach. Gram-positive cocci, bacilli and coccobacilli represented the majority of the isolates. Gastric pH was neutral (pH 7.0 +/- 0.2) in the proximal pouch, whereas the distal chamber mostly but not always conserved the expected acidity (pH 3.3 +/- 2.2, P<0.001). The breath test for bacterial overgrowth was positive in 40.5% of the population.

CONCLUSIONS

1) Frequent colonization of both gastric chambers was detected; 2) Aerobes, anaerobes and fungi were represented in both situations; 3) Gastric pH as well as bacterial count was higher in the functioning proximal stomach; 4) Breath test was positive in 40.5% of the subjects; 5) Clinical manifestation such as diarrhea, malabsorption or pneumonia were not demonstrated; 6) Further histologic and microbiologic studies of both the stomach and the small bowel are recommended.

What to expect in the excluded stomach mucosa after vertical banded Roux-en-Y gastric bypass for morbid obesity

Mucosal alterations after vertical banded Roux-en-Y gastric bypass have not been clearly evaluated. The aim of this paper was to analyze the histological findings and the presence of Helicobacter pylori in the excluded stomach. Forty consecutive patients who underwent Roux-en-Y gastric bypass longer than 36 months were selected for double-balloon enteroscopy. The excluded stomach was reached in 35/40 patients (88%). Morphological alterations were analyzed through hematoxilin and eosin and the presence of H. pylori was confirmed with Giemsa staining. Thirty patients (86%) were female, and the mean age was 43 years old. The mean postoperative time was 78 months (36-110 months). Histologically, all patients had chronic gastritis in the bypassed stomach, with pangastritis in 33/35 (94%). Five cases (5/35, 14%) presented atrophy and four of them also had intestinal metaplasia. Helicobacter pylori was detected in 7/35 (20%) of the excluded stomach and in 12/35 (34%) of the functional pouch. All patients positive for H. pylori in the excluded stomach were also positive in the functional pouch, p = 0.0005. Helicobacter pylori is still present in the excluded stomach after Roux-en-Y gastric bypass and might be considered for treatment. Histological findings indicated high prevalence of atrophy and intestinal metaplasia in this selected population.

Helicobacter pylori infection in patients undergoing gastric bypass surgery for morbid obesity

BACKGROUND

Studies suggest that the incidence of Helicobacter pylori infection in obese patients, including those undergoing gastric reduction surgery, may be increased.

METHODS

We examined the histologic findings at the time of surgery in a series of patients who were undergoing Roux-en-Y gastric bypass (RYGBP) for morbid obesity and compared these results with patients in our institution undergoing endoscopy.

RESULTS

Of 60 patients undergoing RYGBP, material for histologic examination was available in 56 cases, and in 40 cases gastric fundic mucosa from the anastomotic site was sampled at the time of surgery. Active chronic gastritis was present in 6 (15%), and chronic gastritis was present in 27 (68%). H. pylori was present in all 6 cases of active chronic gastritis and in 9 cases of chronic gastritis (total 38%). This incidence of H. pylori infection was higher than that found in the series of gastric biopsies (107/500, 21%, p = 0.03) and fundic biopsies (10/80, 13%, p = 0.003), but was not different when compared with age-matched gastric biopsies (44/177, 25%, p = 0.12).

CONCLUSIONS

The incidence of H. pylori in patients undergoing RYGBP was higher than that found in all patients undergoing endoscopy and biopsy and than those undergoing fundic biopsies, but not higher when age-matched controls were considered.