Changes in the Composition of Oral and Intestinal Microbiota After Sleeve Gastrectomy and Roux-En-Y Gastric Bypass and Their Impact on Outcomes of Bariatric Surgery

Oral microbiome changes in subjects with obesity following bariatric surgery compared to lean counterparts

Introduction

This study aimed to compare oral microbiome profiles between obese and lean individuals without clinical periodontitis, and to assess changes in the oral microbiome of obese subjects following bariatric surgery.

Methods

Individuals with a body mass index (BMI) > 30 were enrolled in the obese group, whereas those with a BMI < 23 served as controls. The obese surgery group, which consented to bariatric surgery, was followed up at 1, 3, and 6 months with clinical examinations. Oral examinations were conducted and periodontal disease was classified based on probing results. Saliva, buccal and subgingival microbiome samples were analyzed for community diversity, relative bacterial abundance, and differential abundance between control (n = 24) and obese group (n = 31). To evaluate effect size and statistical power, we used micropower, a simulation-based method for Permutational Multivariate Analysis of Variance-based β-diversity comparisons.

Results

The obese group exhibited distinct alpha diversity (buccal: Chao1 p = 0.0002, Shannon p = 0.0003, supragingival: Shannon p < 0.0001) compared with the control group. Bray-Curtis distance analysis indicated significant disparities in microbiome composition distribution in saliva (p = 0.003), buccal (p = 0.002), and subgingival plaque samples (p = 0.001). Although the obese and normal weight groups exhibited no significant periodontal differences, the obese group showed distinct species associated with periodontal disease, especially in subgingival plaque including Filifactor alocis, Peptostreptococcaceae spp., Prevotella spp., and Treponema maltophilum. Cluster analysis of the obese surgery group indicated the emergence of microbiomes associated with a healthy state that increased over time including Streptococcus salivarious and various Veillonella spp., whereas clusters containing periodontal pathogens including Porphyromonas spp., tended to diminish.

Discussion

The oral microbiome at 6 months post-bariatric surgery indicates a potential shift toward a healthy periodontal state, suggesting that weight loss interventions may positively impact oral microbial communities even in the absence of clinical periodontitis.

The role of gut microbiota in predicting the weight loss following laparoscopic sleeve gastrectomy

Background

Laparoscopic sleeve gastrectomy (LSG) has emerged as a highly effective intervention in the management of obesity. While there has been a recent surge in research exploring the relationship between obesity and gut microbiota, the association between gut microbiota and LSG remains relatively underexplored. This study aimed to investigate the relationship between gut microbiota and both early and later effects of LSG.

Methods

In this retrospective study, clinical characteristics and preoperative fecal samples were collected from 52 individuals who underwent LSG. Using 16S rRNA gene sequencing, we compared the community composition, alpha diversity, and beta diversity of gut microbiota between patients who experienced efficient weight loss and those who did not. Additionally, comprehensive and correlation analyses were performed to identify potential associations between specific microbial taxa and LSG outcomes.

Results

The abundances of gut microbiota in patients who experienced efficient weight loss and those who experienced general weight loss were comparable. However, the influence of gut microbiota on the efficacy of weight loss is dynamic. Specifically, the Fusobacteriota phylum significantly contributed to the early curative effects of LSG, while Actinobacteriota had a greater impact on the late curative effects. Additionally, Proteobacteria were found to mediate long-term efficacy through complex mechanisms.

Conclusion

This study analyzed the preoperative gut microbiota signature to predict the efficacy of LSG, potentially offering valuable insights for clinical applications. Preoperative assessment of gut microbiota profiles could assist patients in their decision-making processes, particularly regarding the potential outcomes of LSG and the long-term impact of the procedure on their health.

The oral microbial odyssey influencing chronic metabolic disease

INTRODUCTION

Since the oral cavity is the gateway to the gut, oral microbes likely hold the potential to influence metabolic disease by affecting the gut microbiota.

METHOD

A thorough review of literature has been performed to link the alterations in oral microbiota with chronic metabolic disease by influencing the gut microbiota.

RESULT

A strong correlation exists between abnormalities in oral microbiota and several systemic disorders, such as cardiovascular disease, diabetes, and obesity, which likely initially manifest as oral diseases. Ensuring adequate oral hygiene practices and cultivating diverse oral microflora are crucial for the preservation of general well-being. Oral bacteria have the ability to establish and endure in the gastrointestinal tract, leading to the development of prolonged inflammation and activation of the immune system. Oral microbe-associated prophylactic strategies could be beneficial in mitigating metabolic diseases.

CONCLUSION

Oral microbiota can have a profound impact on the gut microbiota and influence the pathogenesis of metabolic diseases.

[Research progress of probiotics regulating intestinal micro-ecological environment in obese patients after bariatric surgery]

Bariatric surgery may cause intestinal microecological environment imbalance due to changes in gastrointestinal anatomy. Some patients may have compli-cations, even regain weight. Probiotics can act on intestinal mucosa, epithelium and gut-associated lymphoid tissue to improve the intestinal microecological environment of obese patients after bariatric surgery. Probiotics can promote the production of short-chain fatty acids, stimulate intestinal cells to release glucagon-like peptide-1, peptide tyrosine-tyrosine, insulin and other endocrine hormones, affect the function of the central nervous system through the gut-brain axis, make patients after bariatric surgery feel full, and reduce blood sugar at the same time. Probiotics can produce lactic acid, acetic acid and lactase, to inhibit the growth of harmful bacteria and to improve gastrointestinal symptoms of patients after bariatric surgery. Probiotics can activate the AMP-activated protein kinase signaling pathway, improve lipid metabolism, and promote the recovery of symptom indicators of nonalcoholic fatty liver disease after bariatric surgery. Probiotics can regulate the release of neurotransmitters or metabolites by the microbiota through the gut-brain axis to affect brain activity and behavior, thus helping patients improve negative emotions after bariatric surgery. This article describes the intestinal microecological environment of obese patients and mechanism of the change after bariatric surgery and summarizes the effects and possible mechanisms of probiotics in improving the intestinal microecological environment of obese patients after bariatric surgery, to provide references for promoting the clinical application of probiotics.

Influence of Bariatric Surgery on Gut Microbiota Composition and Its Implication on Brain and Peripheral Targets

Obesity remains a significant global health challenge, with bariatric surgery remaining as one of the most effective treatments for severe obesity and its related comorbidities. This review highlights the multifaceted impact of bariatric surgery beyond mere physical restriction or nutrient malabsorption, underscoring the importance of the gut microbiome and neurohormonal signals in mediating the profound effects on weight loss and behavior modification. The various bariatric surgery procedures, such as Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), act through distinct mechanisms to alter the gut microbiome, subsequently impacting metabolic health, energy balance, and food reward behaviors. Emerging evidence has shown that bariatric surgery induces profound changes in the composition of the gut microbiome, notably altering the Firmicutes/Bacteroidetes ratio and enhancing populations of beneficial bacteria such as Akkermansia. These microbiota shifts have far-reaching effects beyond gut health, influencing dopamine-mediated reward pathways in the brain and modulating the secretion and action of key gut hormones including ghrelin, leptin, GLP-1, PYY, and CCK. The resultant changes in dopamine signaling and hormone levels contribute to reduced hedonic eating, enhanced satiety, and improved metabolic outcomes. Further, post-bariatric surgical effects on satiation targets are in part mediated by metabolic byproducts of gut microbiota like short-chain fatty acids (SCFAs) and bile acids, which play a pivotal role in modulating metabolism and energy expenditure and reducing obesity-associated inflammation, as well as influencing food reward pathways, potentially contributing to the regulation of body weight and reduction in hedonic eating behaviors. Overall, a better understanding of these mechanisms opens the door to developing non-surgical interventions that replicate the beneficial effects of bariatric surgery on the gut microbiome, dopamine signaling, and gut hormone regulation, offering new avenues for obesity treatment.

Metabolic surgery and oral health: A register-based study

OBJECTIVE

The impact of weight loss surgery on oral health is not clear. The aim of the present study was to investigate its impact on the risk for dental interventions.

MATERIALS AND METHODS

All adults who underwent metabolic surgery in Sweden between January 1, 2009 and December 31, 2018 were identified in the Scandinavian Obesity Surgery Registry (SOReg; n = 53,643). A control cohort from the general population was created, matched 10:1 on sex, age and place of residence (n = 536,430). All individuals were followed in the Swedish Dental Register regarding event rates for four types of dental intervention: restorative, endodontic and periodontal interventions, and tooth extractions.

RESULTS

The surgical cohort had increased interventional rates postoperatively regarding all studied outcomes except periodontal interventions. Dental interventions were more common in the surgical cohort both pre- and postoperatively. The difference between the groups increased markedly in the postoperative period. The between-group comparison postoperatively showed increased event rates for restorations (IRR 1.8; 95% CI 1.7-1.8), extractions (1.9; 95% CI 1.9-2.0) and endodontics (2.1; 95% CI 2.0-2.1).

CONCLUSION

The surgical intervention might cause a substantial negative impact on oral health. These results imply an important role for counselling metabolic surgery patients regarding preventive oral health measures.

The Possible Role of Probiotic Supplementation in Inflammation: A Narrative Review

The fine balance between symbiotic and potentially opportunistic and/or pathogenic microorganisms can undergo quantitative alterations, which, when associated with low intestinal biodiversity, could be responsible for the development of gut inflammation and the so-called "intestinal dysbiosis". This condition is characterized by the disbalance of a fine synergistic mechanism involving the mucosal barrier, the intestinal neuroendocrine system, and the immune system that results in an acute inflammatory response induced by different causes, including viral or bacterial infections of the digestive tract. More frequently, however, dysbiosis is induced slowly and subtly by subliminal causal factors, resulting in a chronic condition related to different diseases affecting the digestive tract and other organs and apparatuses. Studies on animal models, together with studies on humans, highlight the significant role of the gut microbiota and microbiome in the occurrence of inflammatory conditions such as metabolic syndrome and cardiovascular diseases (CVDs); neurodegenerative, urologic, skin, liver, and kidney pathologies; and premature aging. The blood translocation of bacterial fragments has been found to be one of the processes linked to gut dysbiosis and responsible for the possible occurrence of "metabolic endotoxemia" and systemic inflammation, associated with an increased risk of oxidative stress and related diseases. In this context, supplementation with different probiotic strains has been shown to restore gut eubiosis, especially if administered in long-term treatments. The aim of this review is to describe the anti-inflammatory effects of specific probiotic strains observed in clinical trials and the respective indications, highlighting the differences in efficacy depending on strain, formulation, time and duration of treatment, and dosage used.

Swiss expert opinion: current approaches in faecal microbiota transplantation in daily practice

INTRODUCTION

Faecal microbiota transplantation (FMT) is an established therapy for recurrent C. difficile infection, and recent studies have reported encouraging results of FMT in patients with ulcerative colitis. Few international consensus guidelines exist for this therapy, and thus FMT policies and practices differ among European countries. As of 2019, stool transplants are considered a non-standardised medicinal product in Switzerland, and a standardised production process requires authorisation by the Swiss Agency for Therapeutic Products. This authorisation leads to prolonged administrative procedures and increasing costs, which reduces treatment accessibility. In particular, patients with ulcerative colitis in Switzerland can only benefit from FMT off-label, even though it is a valid therapeutic option. Therefore, this study summarised the available data on FMT and established a framework for the standardised use of FMT.

METHODS

A panel of Swiss gastroenterologists with a special interest in inflammatory bowel disease was established to identify the current key issues of FMT. After a comprehensive review of the literature, statements were formulated about FMT indications, donor screening, stool transplant preparation and administration, and safety aspects. The panel then voted on the statements following the Delphi process; the statements were reformulated and revoted until a consensus was reached. The manuscript was then reviewed by an infectiologist (the head of Lausanne's FMT centre).

RESULTS

The established statements are summarised in the supplementary tables in the appendix to this paper. The working group hopes these will help standardise FMT practice in Switzerland and contribute to making faecal microbiota transplantation a safe and accessible treatment for patients with recurrent C. difficile infections and selected patients with ulcerative colitis, as well as other indications in the future.

Impact of Medical and Surgical Obesity Treatment on Dental Caries: A 2-Year Prospective Cohort Study

The objective was to study the long-term effects on oral health of bariatric surgery compared with medical treatment of obesity. Swedish females with morbid obesity (n = 66; 18-35 years at baseline) were followed prospectively from before obesity treatment until 2 years after treatment. The main response variable was dental caries registered according to the ICDAS-II system. Possible confounding factors, such as sociodemographic characteristics, general health, oral health habits, and oral hygiene, were controlled for. The statistical methods included χ2 tests, Student's t tests, one-way ANOVA, Wilcoxon's nonparametric tests, and linear regression models. In the surgically treated patients (n = 40), a significant increase over time in enamel caries (mean increase 4.13 tooth surfaces ICDAS1-2), dentine caries (mean increase 2.18 tooth surfaces ICDAS3-6), and total caries (mean increase 6.30 tooth surfaces ICDAS1-6) was registered (all p < 0.001), which was not seen in the medically treated patients (n = 26). However, the difference between the treatment groups (surgical or medical) was only statistically significant for enamel caries (crude β 4.89, p = 0.003) and total caries (crude β 6.53, p < 0.001). The relationships were stable and independent of differences in confounders as socioeconomy, general health, and oral health behaviors. In conclusion, 2 years after obesity treatment, a significant increase in dental caries was registered in the surgically treated but not in the medically treated women. The dental service should intensify its preventive efforts in individuals undergoing obesity treatment.

Identifying Gut Microbiota associated with Gastrointestinal Symptoms upon Roux-en-Y Gastric Bypass

PURPOSE

Roux-en-Y gastric bypasses (RYGB) are frequently accompanied by long-term gastrointestinal (GI) symptoms. Direct mechanistic insight into the causation of these symptoms is lacking, but changes in the intestinal microbiome have been proposed to play a role. With this study, we aimed to investigate whether a microbial predisposition exists before RYGB which is associated with GI symptoms during follow-up and to evaluate which microbial groups are involved.

MATERIALS AND METHODS

In total, 67 RYGB patients were included. Shotgun metagenomic sequencing was performed on fecal samples obtained just before and 1 year after surgery. To assess GI symptoms, patients filled out Gastrointestinal Quality of Life Index (GIQLI) questionnaires and were divided into groups based on their total GIQLI score and change in score (postsurgery versus baseline). Extremely randomized tree predictor models were used to identify the most distinctive microbial species associated with postoperative GI symptoms.

RESULTS

Beta diversity differed significantly between baseline and 1-year post-surgery samples, with the post-surgery microbiome resembling a more dysbiotic profile. The most predictive species regarding total GIQLI (AUC 0.77) or delta GIQLI score (AUC 0.83) were identified. Many of these species are known butyrate producers or species known to support them and/or species with anti-inflammatory properties, including Coprococcus eutactus, Faecalibacterium prausnitzii, and Ruminococcus callidus.

CONCLUSION

Beneficial commensal gut microbiota related to a high GI score were associated to adequate intestinal fermentative capacity, suggesting these species might have protective properties against postoperative GI malfunctioning.

The gut microbiome: a core regulator of metabolism

The human body is inhabited by numerous bacteria, fungi, and viruses, and each part has a unique microbial community structure. The gastrointestinal tract harbors approximately 100 trillion strains comprising more than 1000 bacterial species that maintain symbiotic relationships with the host. The gut microbiota consists mainly of the phyla Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. Of these, Firmicutes and Bacteroidetes constitute 70-90% of the total abundance. Gut microbiota utilize nutrients ingested by the host, interact with other bacterial species, and help maintain healthy homeostasis in the host. In recent years, it has become increasingly clear that a breakdown of the microbial structure and its functions, known as dysbiosis, is associated with the development of allergies, autoimmune diseases, cancers, and arteriosclerosis, among others. Metabolic diseases, such as obesity and diabetes, also have a causal relationship with dysbiosis. The present review provides a brief overview of the general roles of the gut microbiota and their relationship with metabolic disorders.

The oral microbiome in the pathophysiology of cardiovascular disease

Despite advances in our understanding of the pathophysiology of many cardiovascular diseases (CVDs) and expansion of available therapies, the global burden of CVD-associated morbidity and mortality remains unacceptably high. Important gaps remain in our understanding of the mechanisms of CVD and determinants of disease progression. In the past decade, much research has been conducted on the human microbiome and its potential role in modulating CVD. With the advent of high-throughput technologies and multiomics analyses, the complex and dynamic relationship between the microbiota, their 'theatre of activity' and the host is gradually being elucidated. The relationship between the gut microbiome and CVD is well established. Much less is known about the role of disruption (dysbiosis) of the oral microbiome; however, interest in the field is growing, as is the body of literature from basic science and animal and human investigations. In this Review, we examine the link between the oral microbiome and CVD, specifically coronary artery disease, stroke, peripheral artery disease, heart failure, infective endocarditis and rheumatic heart disease. We discuss the various mechanisms by which oral dysbiosis contributes to CVD pathogenesis and potential strategies for prevention and treatment.

Dysbiosis and Gastrointestinal Surgery: Current Insights and Future Research

Surgery of the gastrointestinal tract can result in deep changes among the gut commensals in terms of abundance, function and health consequences. Elective colorectal surgery can occur for neoplastic or inflammatory bowel disease; in these settings, microbiota imbalance is described as a preoperative condition, and it is linked to post-operative complications, as well. The study of bariatric patients led to several insights into the role of gut microbiota in obesity and after major surgical injuries. Preoperative dysbiosis and post-surgical microbiota reassessment are still poorly understood, and they could become a key part of preventing post-surgical complications. In the current review, we outline the most recent literature regarding agents and molecular pathways involved in pre- and post-operative dysbiosis in patients undergoing gastrointestinal surgery. Defining the standard method for microbiota assessment in these patients could set up the future approach and clinical practice.