Jejunal Luminal and Colonic Mucosa-Associated Microbiota in Metabolic Diseases: Methods, Identification and Causalities

Inclusion Criteria: * General Inclusion Criteria: * Aged between 18 and 60 years; * Ability to understand and provide informed consent (in French); * Ability and willingness to meet the required schedule and study procedures; * Group-Specific Inclusion Criteria: * Control Group Inclusion criteria for the participants from the Control group are: * Presence of Gastroesophageal Reflux Disease symptoms or gastric discomfort. * BMI \[19kg/m² \< BMI \<25 kg/m²\] * Match age and sex to the patients from the Ob and ObD groups. * Only patients with normal glucose tolerance (NGT), glucose tolerance (IGT) and/or fasting glucose (IFG) and an HbA1c \< 6.5 % will be included in this group. * Ob Group Inclusion criteria for the participants from Ob and ObD groups are: ● Candidate for bariatric surgery and meet the HAS criteria (Haute Autorité de Santé, 2009) : * IMC ≥ 40 kg/m² without comorbidities Or IMC≥ 35 kg/m² with at least one obesity-related comorbidity (i.e.: Hypertension, Dyslipidemia, Obstructive Sleep Apnea, Joints Disease, non-alcoholic steatohepatitis, excluding T2D) * Weight stable for at least 2 months * No treatment for metabolic health complications, no previous obesity surgery, no obesity treatment drug. * No monogenic form of obesity (Hebebrand et al., 2017) * ObD Group Inclusion criteria for the participants from ObD groups are: * Candidate for bariatric surgery with T2D * At least one obesity-related comorbidity including T2D * Fasting plasma glucose (FPG) ≥7 mM (=1.26g/l) or * Participants with HbA1c ≥ 6.5% (48 mmol/mol) * All stages of albuminuria Exclusion Criteria: * General Non-inclusion Criteria: * Treatment for the previous 12 week that could * alter gastrointestinal motor function (e.g. opioids, prokinetics, anticholinergics, laxatives), * acidity (PPI, H2RA) * microbial population (e.g.: antibiotics, probiotics) * immunosuppressants (eg: calcineurin inhibitors, corticosteroids, biological agents, etc.). * use of weight-loss drug or dietary intervention aiming to lose weight; * Altered anatomy of the esophagus, stomach, small or large intestine due to prior gastrointestinal surgery (exceptions include appendectomy or cholecystectomy more than 3 months prior to enrollment) or other reasons; * Any abdominal or pelvic surgery within the past 3 months; * Diverticulitis, diverticular stricture, or other intestinal strictures. * Intestinal resection of the gastrointestinal tract * Previous history of gastric bezoar or gastroparesis * Acute or chronic inflammatory bowel disease or infections diseases (i.e.: VHC, VHB, VIH, etc.) * Abdominal or pelvic radiotherapy or abdominal cancer * Colorectal cancer, either known or not * Dysphagia, eosinophilic esophagitis, esophageal stricture, or other swallowing disorder * Organ Transplantation and patients on Immunosuppressive Therapy * Severe kidney failure and/or patients on dialysis therapy (serum creatinine \> 150 μmol/l or eGFR \< 60 ml/min per 1.73 m2 body surface area) * CVD, endocrine, renal or other chronic disease likely to affect motility. * Colon cleansing preparation during the last 1 month * No \< 3 bowel movements per week * Females of childbearing age who do not practice birth control and/or are pregnant or lactating * Participants non-affiliated to the French national health scheme * Participants who are already included in a clinical study which implies testing any pharmaceutical drug. * Participants who do not understand the research procedures those who are institutionalized, or who unable to give informed consent * Participants placed under legal protection * Patients with drug addiction * Antibiotherapy 3 months preceding the endoscopy * Weight variation (diminution or increase) \> 5kg in the last 3 months * Specific non-inclusion Criteria * Ob and ObT2D Group * Usual contraindication for bariatric surgery;