Clinical Research Directory

Inclusion Criteria: * Cases: patients aged 17 years or older with obesity scheduled for elective sleeve gastrectomy according to the 2022 ASMBS/IFSO indications for metabolic and bariatric surgery. * Controls: participants aged 17 years or older with BMI below 30 kg/m² undergoing diagnostic upper gastrointestinal endoscopy for benign indications, such as mild dyspepsia, with no endoscopic evidence of active gastric mucosal disease. * Negative rapid urease test for Helicobacter pylori on antral biopsy. * Written informed consent. Exclusion Criteria: * Positive rapid urease test. * Active erosive gastritis, peptic ulcer disease, or suspected or confirmed gastric malignancy at endoscopy. * Current cigarette smoking, or smoking cessation within 6 months before enrollment. * Prior gastric surgery. * Secondary causes of obesity, such as Cushing's syndrome or hypothyroidism. * Systemic autoimmune disease or inflammatory bowel disease. * Active malignancy, or a major systemic infection within 3 months before sampling. * Long-term non-steroidal anti-inflammatory drug use, proton pump inhibitor use for more than 6 months, or immunosuppressive or corticosteroid therapy within 3 months before sampling. * For controls: BMI of 30 kg/m² or higher.