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Gastrointestinal Transcriptomic Response of Metabolic Vitamin B12 Pathways in Roux-en-Y Gastric Bypass.

ABSTRACT: Vitamin B12 (B12) deficiency after Roux-en-Y gastric bypass (RYGB) is highly prevalent and may contribute to postoperative complications. Decreased production of intrinsic factor owing to gastric fundus removal is thought to have a major role, but other components of B12 metabolism may also be affected. We evaluated changes in the expression levels of multiple B12 pathway-encoding genes in gastrointestinal (GI) tissues to evaluate the potential roles in contributing to post-RYGB B12 deficiency.During double-balloon enteroscopy, serial GI biopsies were collected from 20 obese women (age, 46.9±6.2 years; body mass index, 46.5±5.3?kg/m2) with adult-onset type 2 diabetes (fasting plasma glucose ?126?mg/dl; hemoglobin A1c?6.5%) before and, at the same site, 3 months after RYGB. Gene expression levels were assessed by the Affymetrix Human GeneChip 1.0 ST microarray. Findings were validated by real-time quantitative PCR (RT-qPCR).Gene expression levels with significant changes (P?0.05) included: transcobalamin I (TCN1) in remnant (-1.914-fold) and excluded (-1.985-fold) gastric regions; gastric intrinsic factor (GIF) in duodenum (-0.725-fold); and cubilin (CUBN) in duodenum (+0.982-fold), jejunum (+1.311-fold), and ileum (+0.685-fold). Validation by RT-qPCR confirmed (P?0.05) observed changes for TCN1 in the remnant gastric region (-0.132-fold) and CUBN in jejunum (+2.833-fold).RYGB affects multiple pathway-encoding genes that may be associated with postoperative B12 deficiency. Decreased TCN1 levels seem to be the main contributing factor. Increased CUBN levels suggest an adaptive genetic reprogramming of intestinal tissue aiming to compensate for impaired intestinal B12 delivery.

SUBMITTER: Sala P

PROVIDER: S-EPMC5288601 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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Gastrointestinal Transcriptomic Response of Metabolic Vitamin B12 Pathways in Roux-en-Y Gastric Bypass.

Sala Priscila P Belarmino Giliane G Torrinhas Raquel S RS Machado Natasha M NM Fonseca Danielle C DC Ravacci Graziela R GR Ishida Robson K RK Guarda Ismael F M S IF de Moura Eduardo G EG Sakai Paulo P Santo Marco A MA da Silva Ismael D C G ID Pereira Claudia C A CC Logullo Angela F AF Heymsfield Steven S Giannella-Neto Daniel D Waitzberg Dan L DL

Clinical and translational gastroenterology 20170105 1

<h4>Objectives</h4>Vitamin B12 (B12) deficiency after Roux-en-Y gastric bypass (RYGB) is highly prevalent and may contribute to postoperative complications. Decreased production of intrinsic factor owing to gastric fundus removal is thought to have a major role, but other components of B12 metabolism may also be affected. We evaluated changes in the expression levels of multiple B12 pathway-encoding genes in gastrointestinal (GI) tissues to evaluate the potential roles in contributing to post-RY ...[more]

PMID: 28055029

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Project description:ObjectiveObesity leads to severe long-term complications and reduced life expectancy. Roux-en-Y gastric bypass (RYGB) surgery induces excessive and continuous weight loss in (morbid) obesity, although it causes several abnormal anatomical and physiological conditions.Research design and methodsTo distinctively unveil effects of RYGB surgery on ?-cell function and glucose turnover in skeletal muscle, liver, and gut, nondiabetic, morbidly obese patients were studied before (pre-OP, five female/one male, BMI: 49 ± 3 kg/m(2), 43 ± 2 years of age) and 7 ± 1 months after (post-OP, BMI: 37 ± 3 kg/m(2)) RYGB surgery, compared with matching obese (CON(ob), five female/one male, BMI: 34 ± 1 kg/m(2), 48 ± 3 years of age) and lean controls (CON(lean), five female/one male, BMI: 22 ± 0 kg/m(2), 42 ± 2 years of age). Oral glucose tolerance tests (OGTTs), hyperinsulinemic-isoglycemic clamp tests, and mechanistic mathematical modeling allowed determination of whole-body insulin sensitivity (M/I), OGTT and clamp test ?-cell function, and gastrointestinal glucose absorption.ResultsPost-OP lost (P < 0.0001) 35 ± 3 kg body weight. M/I increased after RYGB, becoming comparable to CON(ob), but remaining markedly lower than CON(lean) (P < 0.05). M/I tightly correlated (? = -0.611, P < 0.0001) with fat mass. During OGTT, post-OP showed ?15% reduced plasma glucose from 120 to 180 min (?4.5 mmol/L), and 29-fold elevated active glucagon-like peptide-1 (GLP-1) dynamic areas under the curve, which tightly correlated (r = 0.837, P < 0.001) with 84% increased ?-cell secretion. Insulinogenic index (0-30 min) in post-OP was ?29% greater (P < 0.04). At fasting, post-OP showed approximately halved insulin secretion (P < 0.05 vs. pre-OP). Insulin-stimulated insulin secretion in post-OP was 52% higher than before surgery, but 1-2 pmol/min(2) lower than in CON(ob)/CON(lean) (P < 0.05). Gastrointestinal glucose absorption was comparable in pre-OP and post-OP, but 9-26% lower from 40 to 90 min in post-OP than in CON(ob)/CON(lean) (P < 0.04).ConclusionsRYGB surgery leads to decreased plasma glucose concentrations in the third OGTT hour and exaggerated ?-cell function, for which increased GLP-1 release seems responsible, whereas gastrointestinal glucose absorption remains unchanged but lower than in matching controls.

Dataset Information

Gastrointestinal Transcriptomic Response of Metabolic Vitamin B12 Pathways in Roux-en-Y Gastric Bypass.

Publications

Gastrointestinal Transcriptomic Response of Metabolic Vitamin B12 Pathways in Roux-en-Y Gastric Bypass.

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