Impairment of gut microbial biotin metabolism and host biotin status in severe obesity: effect of biotin and prebiotic supplementation on improved metabolism.

OBJECTIVES: Gut microbiota is a key component in obesity and type 2 diabetes, yet mechanisms and metabolites central to this interaction remain unclear. We examined the human gut microbiome's functional composition in healthy metabolic state and the most severe states of obesity and type 2 diabetes within the MetaCardis cohort. We focused on the role of B vitamins and B7/B8 biotin for regulation of host metabolic state, as these vitamins influence both microbial function and host metabolism and inflammation. DESIGN: We performed metagenomic analyses in 1545 subjects from the MetaCardis cohorts and different murine experiments, including germ-free and antibiotic treated animals, faecal microbiota transfer, bariatric surgery and supplementation with biotin and prebiotics in mice. RESULTS: Severe obesity is associated with an absolute deficiency in bacterial biotin producers and transporters, whose abundances correlate with host metabolic and inflammatory phenotypes. We found suboptimal circulating biotin levels in severe obesity and altered expression of biotin-associated genes in human adipose tissue. In mice, the absence or depletion of gut microbiota by antibiotics confirmed the microbial contribution to host biotin levels. Bariatric surgery, which improves metabolism and inflammation, associates with increased bacterial biotin producers and improved host systemic biotin in humans and mice. Finally, supplementing high-fat diet-fed mice with fructo-oligosaccharides and biotin improves not only the microbiome diversity, but also the potential of bacterial production of biotin and B vitamins, while limiting weight gain and glycaemic deterioration. CONCLUSION: Strategies combining biotin and prebiotic supplementation could help prevent the deterioration of metabolic states in severe obesity. TRIAL REGISTRATION NUMBER: NCT02059538.

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.

Diabetic foot ulcer management in a multidisciplinary foot centre: one-year healing, amputation and mortality rate.

OBJECTIVE: To describe the rates of healing, major amputation and mortality after 12 months in patients with a new diabetic foot ulcer (DFU) and their care in a French diabetic foot service (DFS). METHOD: A prospective single-centre study including patients from March 2009 to December 2010. The length of time to healing, minor amputation, major amputation and mortality rate after inclusion were analysed using the Kaplan-Meier method. RESULTS: Some 347 patients were included (3% lost to follow-up), with a median follow-up (IQR) of 19 (12-24) months. The mean (SD) age was 65±12 years, 68% were male, and the median duration of the ulcer was 49 (19-120) days. Complications of the DFU were ischaemia (70%), infection (55%) and osteomyelitis (47%). Of the patients, 50% were inpatients in the DFS at inclusion (median duration of hospitalisation 26 (15-41) days). The rate of healing at one year was 67% (95% confidence interval (CI): 61-72); of major amputation 10% (95% CI: 7-17); of minor amputation 19% (95% CI: 14-25), and the death rate was 9% (95% CI: 7-13). Using an adjusted hazard ratio, the predictive factors of healing were perfusion and the area of the wound. The risk factors for a major amputation were active smoking and osteomyelitis. The risk factors for mortality were perfusion and age. CONCLUSION: This study confirms the need to treat DFUs rapidly, in a multidisciplinary DFS.

Weight Loss After Sleeve Gastrectomy: Does Type 2 Diabetes Status Impact Weight and Body Composition Trajectories?

INTRODUCTION/ PURPOSE: Sleeve gastrectomy (SG), the most frequently performed bariatric procedure, induces marked weight-loss, but with high inter-individual variability. Since type 2 diabetes (T2D) negatively impacts weight-loss outcomes after Roux-en-Y gastric bypass (RYGB), we herein aimed to evaluate whether and how T2D status may influence weight-loss and body composition changes in individuals with or without T2D after SG. MATERIAL AND METHODS: We retrospectively included individuals with obesity operated from SG and prospectively followed at our center: 373 patients including 152 with T2D (40%). All subjects' clinical characteristics were collected before and during 4 years of follow-up post-SG. Linear mixed models were applied to analyze weight-loss trajectories post-surgery. RESULTS: Compared to individuals with obesity but no T2D, those with T2D before SG displayed lower weight-loss at 1 year (21 vs. 27% from baseline, p < 10-3). This difference was accentuated in patients with poorer glucose control (HbA1c > 7%) at baseline. Furthermore, patients with T2D underwent less favorable body composition changes at 1-year post-SG compared to individuals without T2D (% fat mass reduction: 28 vs. 37%, p < 10-3 respectively). CONCLUSION: When undergoing SG, subjects with obesity and T2D who have poor pre-operative glycemic control display reduced weight-loss and less improvement in body composition compared to patients with obesity but without T2D. This result suggests that glycemic control prior to surgery is important to take into account for the outcome of bariatric surgery.

Circulating Receptor Activator of Nuclear Factor kB Ligand and triglycerides are associated with progression of lower limb arterial calcification in type 2 diabetes: a prospective, observational cohort study.

BACKGROUND: Lower limb arterial calcification is a frequent, underestimated but serious complication of diabetes. The DIACART study is a prospective cohort study designed to evaluate the determinants of the progression of lower limb arterial calcification in 198 patients with type 2 diabetes. METHODS: Lower limb arterial calcification scores were determined by computed tomography at baseline and after a mean follow up of 31.20 ± 3.86 months. Serum RANKL (Receptor Activator of Nuclear factor kB Ligand) and bone remodeling, inflammatory and metabolic parameters were measured at baseline. The predictive effect of these markers on calcification progression was analyzed by a multivariate linear regression model. RESULTS: At baseline, mean ± SD and median lower limb arterial calcification scores were, 2364 ± 5613 and 527 respectively and at the end of the study, 3739 ± 6886 and 1355 respectively. Using multivariate analysis, the progression of lower limb arterial log calcification score was found to be associated with (ß coefficient [slope], 95% CI, p-value) baseline log(calcification score) (1.02, 1.00-1.04, p < 0.001), triglycerides (0.11, 0.03-0.20, p = 0.007), log(RANKL) (0.07, 0.02-0.11, p = 0.016), previous ischemic cardiomyopathy (0.36, 0.15-0.57, p = 0.001), statin use (0.39, 0.06-0.72, p = 0.023) and duration of follow up (0.04, 0.01-0.06, p = 0.004). CONCLUSION: In patients with type 2 diabetes, lower limb arterial calcification is frequent and can progress rapidly. Circulating RANKL and triglycerides are independently associated with this progression. These results open new therapeutic perspectives in peripheral diabetic calcifying arteriopathy. Trial registration NCT02431234.

A surrogate of Roux-en-Y gastric bypass (the enterogastro anastomosis surgery) regulates multiple beta-cell pathways during resolution of diabetes in ob/ob mice.

BACKGROUND: Bariatric surgery is an effective treatment for type 2 diabetes. Early post-surgical enhancement of insulin secretion is key for diabetes remission. The full complement of mechanisms responsible for improved pancreatic beta cell functionality after bariatric surgery is still unclear. Our aim was to identify pathways, evident in the islet transcriptome, that characterize the adaptive response to bariatric surgery independently of body weight changes. METHODS: We performed entero-gastro-anastomosis (EGA) with pyloric ligature in leptin-deficient ob/ob mice as a surrogate of Roux-en-Y gastric bypass (RYGB) in humans. Multiple approaches such as determination of glucose tolerance, GLP-1 and insulin secretion, whole body insulin sensitivity, ex vivo glucose-stimulated insulin secretion (GSIS) and functional multicellular Ca2+-imaging, profiling of mRNA and of miRNA expression were utilized to identify significant biological processes involved in pancreatic islet recovery. FINDINGS: EGA resolved diabetes, increased pancreatic insulin content and GSIS despite a persistent increase in fat mass, systemic and intra-islet inflammation, and lipotoxicity. Surgery differentially regulated 193 genes in the islet, most of which were involved in the regulation of glucose metabolism, insulin secretion, calcium signaling or beta cell viability, and these were normalized alongside changes in glucose metabolism, intracellular Ca2+ dynamics and the threshold for GSIS. Furthermore, 27 islet miRNAs were differentially regulated, four of them hubs in a miRNA-gene interaction network and four others part of a blood signature of diabetes resolution in ob/ob mice and in humans. INTERPRETATION: Taken together, our data highlight novel miRNA-gene interactions in the pancreatic islet during the resolution of diabetes after bariatric surgery that form part of a blood signature of diabetes reversal. FUNDING: European Union's Horizon 2020 research and innovation programme via the Innovative Medicines Initiative 2 Joint Undertaking (RHAPSODY), INSERM, Société Francophone du Diabète, Institut Benjamin Delessert, Wellcome Trust Investigator Award (212625/Z/18/Z), MRC Programme grants (MR/R022259/1, MR/J0003042/1, MR/L020149/1), Diabetes UK (BDA/11/0004210, BDA/15/0005275, BDA 16/0005485) project grants, National Science Foundation (310030-188447), Fondation de l'Avenir.

Diabetic foot ulcer management in a multidisciplinary foot centre: one-year healing, amputation and mortality rate.

OBJECTIVE: To describe the rates of healing, major amputation and mortality after 12 months in patients with a new diabetic foot ulcer (DFU) and their care in a French diabetic foot service (DFS). METHOD: A prospective single-centre study including patients from March 2009 to December 2010. The length of time to healing, minor amputation, major amputation and mortality rate after inclusion were analysed using the Kaplan-Meier method. RESULTS: Some 347 patients were included (3% lost to follow-up), with a median follow-up (IQR) of 19 (12-24) months. The mean (SD) age was 65±12 years, 68% were male, and the median duration of the ulcer was 49 (19-120) days. Complications of the DFU were ischaemia (70%), infection (55%) and osteomyelitis (47%). Of the patients, 50% were inpatients in the DFS at inclusion (median duration of hospitalisation 26 (15-41) days). The rate of healing at one year was 67% (95% confidence interval (CI): 61-72); of major amputation 10% (95% CI: 7-17); of minor amputation 19% (95% CI: 14-25), and the death rate was 9% (95% CI: 7-13). Using an adjusted hazard ratio, the predictive factors of healing were perfusion and the area of the wound. The risk factors for a major amputation were active smoking and osteomyelitis. The risk factors for mortality were perfusion and age. CONCLUSION: This study confirms the need to treat DFUs rapidly, in a multidisciplinary DFS.

Diabetes Mellitus, Extreme Insulin Resistance, and Hypothalamic-Pituitary Langerhans Cells Histiocytosis.

BACKGROUND: Langerhans Cell Histiocytosis (LCH) is a rare inflammatory neoplasm characterized by an infiltration of organs by Langerin + (CD207+) and CD1a+ histiocytes. Diabetes insipidus is a frequent manifestation of the disease, while diabetes mellitus is very rare. We report the first case of a 20-year-old man suffering from hypothalamopituitary histiocytosis and diabetes mellitus with serum anti-insulin receptor antibodies. CASE PRESENTATION: A 20-year-old patient was admitted for the evaluation of growth delay and hyperphagia. HbA1c level and fasting blood glucose were in the normal range. The diagnosis of hypothalamopituitary histiocytosis was based on histological features after biopsy of a large suprachiasmatic lesion identified on magnetic resonance imaging (MRI). Association of vinblastine and purinethol was started followed by a second-line therapy by cladribine. During the follow-up, the patient was admitted for recurrence of hyperglycemic states and extreme insulin resistance. The screening for serum anti-insulin receptor antibodies was positive. Each episode of hyperglycemia appeared to be correlated with tumoral activity and increase in serum anti-insulin receptor antibodies and appeared to be improved when the disease was controlled by chemotherapy. CONCLUSION: We report the first description of a hypothalamopituitary histiocytosis associated with serum anti-insulin receptor antibodies, extreme insulin resistance, and diabetes. Parallel evolution of glucose levels and serum anti-insulin receptor antibodies seemed to be the consequence of immune suppressive properties of cladribine.

Impact of bariatric surgery on type 2 diabetes: contribution of inflammation and gut microbiome?

Obesity is a chronic low-grade inflammatory disease (both at the systemic and adipose tissue level) that continues to rise worldwide. It is associated with an abundance of comorbidities, including type 2 diabetes (T2D). Bariatric surgery, which induces modifications of the intestinal tract, is to date the most successful treatment for obesity. Its use has dramatically increased in number as it enables both weight reduction and metabolic improvements, with 60% of patients even achieving diabetes remission. Several mechanisms are actually demonstrated to be involved in those clinical improvements. Importantly, both obesity and T2D share many phenotypic characteristics, including increased systemic and adipose tissue inflammation, as well as gut microbiota dysbiosis. These characteristics are deeply modulated after bariatric surgery. This review will address the host metabolic changes observed after bariatric surgery, focusing on the induced gut architectural changes, as well as on the modifications of the inflammatory tone and the gut microbiota.

Sleeve Gastrectomy in Morbidly Obese HIV Patients: Focus on Anti-retroviral Treatment Absorption After Surgery.

CONTEXT: Anti-retroviral therapy (ART) dramatically reduced AIDS development, thus enabling patients to live as long as the general population. New challenges have emerged particularly cardiometabolic diseases and weight gain, with some HIV patients seeking bariatric surgery (BS). However, BS outcomes during HIV remain poorly described, with scarce data on ART pharmacokinetic post-BS. OBJECTIVE: Describing sleeve gastrectomy (SG) results in HIV patients in terms of ART pharmacokinetic, HIV control, weight loss, and metabolic outcomes. DESIGN, SETTING, AND PATIENTS: Prospective study of HIV patients undergoing SG in a referral academic center, with at least 6 months follow-up. MAIN OUTCOME MEASURE: Clinical and biological parameters, HIV medical history, and ART pharmacokinetics were gathered before and post-SG. RESULTS: Seventeen patients (mean BMI = 44.2 ± 5.7 kg m-2) and major obesity-related diseases (47% type-2 diabetes, 64% obstructive sleep apnea, 70% hypertension) underwent SG during a mean 2 years of follow-up. They displayed an average of 20% reduction of initial BMI and improved body composition, similarly to obese non-HIV patients. SG improved metabolic status. All patients had undetectable viral load before BS. Upon HIV follow-up, 12 patients had undetectable viral load with correct ART kinetic parameters (3 and 6 months); 4 displayed detectable viral load along with significant decrease in raltegravir and atazanavir treatment exposure, leading to ART change with subsequent undetectable viral load; and 1 had persistent detectable viral load despite ART change. CONCLUSIONS: SG seems effective and safe in obese HIV patients. However, ART treatment should be monitored post-SG to control HIV infection. We suggest that some ART should be adapted before SG conjoints with infectious disease specialists.

Increasing GLP-1 Circulating Levels by Bariatric Surgery or by GLP-1 Receptor Agonists Therapy: Why Are the Clinical Consequences so Different?

The "incretin effect" is used to describe the observation that more insulin is secreted after the oral administration of glucose compared to that after the intravenous administration of the same amount of glucose. During the absorption of meals, the gut is thought to regulate insulin secretion by secreting a specific factor that targets pancreatic beta cells. Additional research confirmed this hypothesis with the discovery of two hormones called incretins: gastric inhibitory peptide (GIP) and glucagon-like peptide 1 (GLP-1). During meals, specific cells in the gut (L and K enteroendocrine cells) secrete incretins, causing an increase in the blood concentrations of, respectively, GLP-1 and GIP. Bariatric surgery is now proposed during the therapeutic management of type 2 diabetes in obese or overweight populations. It has been hypothesized that restoration of endogenous GLP-1 secretion after the surgery may contribute to the postsurgical resolution of diabetes. In 2005, the commercialization of GLP-1 receptor agonists gave the possibility to test this hypothesis. A few years later, it is now accepted that GLP-1 receptor agonists and bariatric surgery differently improve type 2 diabetes. These differences between endogenous and exogenous GLP-1 on glucose homeostasis emphasized the dual properties of GLP-1 as a peptide hormone and as a neurotransmitter.

Peripheral activation of the Y2-receptor promotes secretion of GLP-1 and improves glucose tolerance.

The effect of peptide tyrosine-tyrosine (PYY) on feeding is well established but currently its role in glucose homeostasis is poorly defined. Here we show in mice, that intraperitoneal (ip) injection of PYY3-36 or Y2R agonist improves nutrient-stimulated glucose tolerance and enhances insulin secretion; an effect blocked by peripheral, but not central, Y2R antagonist administration. Studies on isolated mouse islets revealed no direct effect of PYY3-36 on insulin secretion. Bariatric surgery in mice, enterogastric anastomosis (EGA), improved glucose tolerance in wild-type mice and increased circulating PYY and active GLP-1. In contrast, in Pyy-null mice, post-operative glucose tolerance and active GLP-1 levels were similar in EGA and sham-operated groups. PYY3-36 ip increased hepato-portal active GLP-1 plasma levels, an effect blocked by ip Y2R antagonist. Collectively, these data suggest that PYY3-36 therefore acting via peripheral Y2R increases hepato-portal active GLP-1 plasma levels and improves nutrient-stimulated glucose tolerance.

Differential pre-mRNA splicing regulates Nnat isoforms in the hypothalamus after gastric bypass surgery in mice.

BACKGROUND: Neuronatin (NNAT) is an endoplasmic reticulum proteolipid implicated in intracellular signalling. Nnat is highly-expressed in the hypothalamus, where it is acutely regulated by nutrients and leptin. Nnat pre-mRNA is differentially spliced to create Nnat-α and -ß isoforms. Genetic variation of NNAT is associated with severe obesity. Currently, little is known about the long-term regulation of Nnat. METHODS: Expression of Nnat isoforms were examined in the hypothalamus of mice in response to acute fast/feed, chronic caloric restriction, diet-induced obesity and modified gastric bypass surgery. Nnat expression was assessed in the central nervous system and gastrointestinal tissues. RTqPCR was used to determine isoform-specific expression of Nnat mRNA. RESULTS: Hypothalamic expression of both Nnat isoforms was comparably decreased by overnight and 24-h fasting. Nnat expression was unaltered in diet-induced obesity, or subsequent switch to a calorie restricted diet. Nnat isoforms showed differential expression in the hypothalamus but not brainstem after bypass surgery. Hypothalamic Nnat-ß expression was significantly reduced after bypass compared with sham surgery (P = 0.003), and was positively correlated with post-operative weight-loss (R(2) = 0.38, P = 0.01). In contrast, Nnat-α expression was not suppressed after bypass surgery (P = 0.19), and expression did not correlate with reduction in weight after surgery (R(2) = 0.06, P = 0.34). Hypothalamic expression of Nnat-ß correlated weakly with circulating leptin, but neither isoform correlated with fasting gut hormone levels post- surgery. Nnat expression was detected in brainstem, brown-adipose tissue, stomach and small intestine. CONCLUSIONS: Nnat expression in hypothalamus is regulated by short-term nutrient availability, but unaltered by diet-induced obesity or calorie restriction. While Nnat isoforms in the hypothalamus are co-ordinately regulated by acute nutrient supply, after modified gastric bypass surgery Nnat isoforms show differential expression. These results raise the possibility that in the radically altered nutrient and hormonal milieu created by bypass surgery, resultant differential splicing of Nnat pre-mRNA may contribute to weight-loss.