Effect of Roux-en-Y Gastric Bypass on circulating oxylipin profile in women with obesity and type 2 diabetes.

BACKGROUND & AIMS: Chronic inflammation associated with obesity directly contributes to metabolic comorbidities, including type 2 diabetes (T2D). Roux-en-Y gastric bypass (RYGB) is a highly effective treatment for obesity-associated T2D. We investigated the effect of RYGB on the circulating profile of oxylipins derived from arachidonic (ARA), eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids as a potential mechanism underlying the metabolic benefits of the surgery. METHODS: Plasma samples were collected from 28 women with obesity and T2D before and 3 months after RYGB. Circulating levels of oxylipins and their precursors, along with biochemical markers of glucose homeostasis, were evaluated using untargeted mass spectrometry and routine biochemical techniques, respectively. RESULTS: No significant changes were observed in the levels of oxylipins derived from EPA and DHA. However, there was an increase in ARA and its derived oxylipins, TXB2 (an inert derivative of TXA2) and PGD2 (Wilcoxon, p ≤ 0.05). Positive correlations were observed between hemoglobin A1c levels and TXB2 as well as ARA levels (Spearman, p ≤ 0.05). CONCLUSIONS: Our data suggest that the anti-inflammatory oxylipins derived from EPA and DHA may not be involved in the metabolic benefits associated with RYGB. However, the findings indicate that the pro-inflammatory oxylipin TXA2 and its precursor ARA may negatively impact glucose homeostasis both before and after RYGB.

Roux-en-Y gastric bypass affects the expression of genes related to the intestinal folate metabolism pathway in obese women.

OBJECTIVES: Roux-en-Y gastric bypass (RYGB) promotes sustained weight loss, and the resulting new gastrointestinal anatomy can contribute to nutritional depletions. Folate deficiency is one of the most frequently observed nutritional deficiencies after RYGB. The aim of this study was to assess whether RYGB affects the expression of genes related to the intestinal folate metabolism pathway as an additional molecular mechanism contributing to its postoperative deficiency. METHODS: Biopsies from the duodenum, jejunum, and ileum of 20 obese women were collected before and 3 mo after RYGB. The expression of genes involved in intestinal folate metabolism was assessed by microarray and reverse transcriptase polymerase chain reaction (RT-qPCR). Folate intake (7-d food record) and plasma levels (electrochemiluminescence) also were measured. RESULTS: Compared with the preoperative phase, transcriptomic alterations were observed in all intestinal segments studied after RYBG, mainly marked by decreased expression of genes encoding folate transporters/receptors and increased expression of genes involved in folate biosynthesis (P < 0.05). Reduced folate intake and plasma folate levels were also observed simultaneously (P < 0.05). Plasma folate concentrations correlated inversely with intestinal FOLR2 and SHMT2 genes (P < 0.001). CONCLUSION: The present findings suggested that impaired expression of genes related to intestinal folate metabolism may contribute to the early systemic deficiency after RYGB and highlight a potential transcriptomic reprogramming of the intestine in response to RYGB to compensate for folate depletion induced by this surgical technique.

Red Meat Intake, Indole-3-Acetate, and Dorea longicatena Together Affect Insulin Resistance after Gastric Bypass.

Roux-en-Y Gastric bypass (RYGB) promotes improvement in type 2 diabetes (T2D) shortly after surgery, with metabolic mechanisms yet to be elucidated. This study aimed to investigate the relationship between food intake, tryptophan metabolism, and gut microbiota on the glycemic control of obese T2D women after RYGB surgery. Twenty T2D women who underwent RYGB were evaluated before and three months after surgery. Food intake data were obtained by a seven-day food record and a food frequency questionnaire. Tryptophan metabolites were determined by untargeted metabolomic analysis, and the gut microbiota was determined by 16S rRNA sequencing. The glycemic outcomes were fasting blood glucose, HbA1C, HOMA-IR, and HOMA-beta. Linear regression models were applied to assess the associations between the changes in food intake, tryptophan metabolism, and gut microbiota on glycemic control after RYGB. All variables changed after RYGB (p < 0.05), except for tryptophan intake. Jointly, the variation in red meat intake, plasma indole-3-acetate, and Dorea longicatena was associated with postoperative HOMA-IR {R2 0.80, R2 adj 0.74; p < 0.01}. Red meat intake decreased three months after bariatric surgery while indole-3-acetate and Dorea longicatena increased in the same period. These combined variables were associated with better insulin resistance in T2D women after RYGB.

Gastrointestinal genetic reprogramming of vitamin A metabolic pathways in response of Roux-en-Y gastric bypass.

Roux-en-Y gastric bypass (RYGB) is one of the most performed bariatric surgical techniques. However, RYGB commonly results, as side effects, in nutritional deficiencies. This study aimed to examine changes in the expression of vitamin A pathway encoding genes in the gastrointestinal tract (GI) and to evaluate the potential mechanisms associated with hypovitaminosis A after RYGB. Intestinal biopsies were obtained through double-balloon endoscopy in 20 women with obesity (age 46.9±6.2 years; body mass index [BMI] 46.5±5.3 kg/m2 [mean±SD]) before and three months after RYGB (BMI, 38.2±4.2 kg/m2). Intestinal mucosal gene microarray analyses were performed in samples using a Human GeneChip 1.0 ST array (Affymetrix). Vitamin A intake was assessed from 7-day food records and serum retinol levels were evaluated by electrochemiluminescence immunoassay. Our results showed the following genes with significant downregulation (p≤0.05): LIPF (-0.60), NPC1L1 (-0.71), BCO1 (-0.45), and RBP4 (-0.13) in duodenum; CD36 (-0.33), and ISX (-0.43) in jejunum and BCO1 (-0.29) in ileum. No significant changes in vitamin A intake were found (784±694 retinol equivalents [RE] pre-operative vs. 809±753 RE post-operative [mean±SD]). Although patients were routinely supplemented with 3500 international units IU/day (equivalent to 1050 µg RE/day) of oral retinol palmitate, serum concentrations were lower in the post-operative when compared to pre-operative period (0.35±0.14 µg/L vs. 0.52±0.33 µg/L, respectively - P=0.07), both within the normal range. After RYGB, the simultaneous change in expression of GI genes, may impair carotenoid metabolism in the enterocytes, formation of nascent chylomicrons and transport of retinol, resulting in lower availability of vitamin A.

Genetic reprogramming of remnant duodenum may contribute to type 2 diabetes improvement after Roux-en-Y gastric bypass.

OBJECTIVES: Type 2 diabetes control occurs within a few days after Roux-en-Y gastric bypass (RYGB) and might be related to intestinal adaptation to the new anatomic arrangement. The aim of this study was to evaluate the intestinal transcriptome response to RYGB and its correlation with markers of glycemic homeostasis. METHODS: Global transcriptomic analyses performed by microarray technique were conducted in intestinal biopsies collected from adult women with obesity (N = 20) and T2D before and 3 mo after RYGB. Clinical and biochemical markers of glycemic homeostasis were also evaluated. At 1-y postoperative, patients were classified as responsive (R) or non-responsive (NR) to complete T2D remission according to the American Diabetes Association criteria. Intestinal differentially expressed genes (DEGs) were analyzed separately in the two groups, validated by reverse transcription quantitative polymerase chain reaction, and applied in functional enrichment and canonical pathway analysis. Spearman correlations between clinical and biochemical variables with DEGs were conducted. Twelve patients were classified as R and displayed 62 (duodenum), 241 (jejunum), and 63 (ileum) DEGs. RESULTS: Eight of the patients with DEGs presented very strong or strong positive correlations with glycemia or glycated hemoglobin. Duodenal changes of genes involved in the LXR/RXR pathway were more likely to be associated with T2D. CONCLUSION: In obese women, complete remission of T2D after RYGB might include intestinal transcriptomic changes that suggest a potential role of intracellular cholesterol and lipid homeostasis on glucose control.

Cholecystectomy - a potential selection bias in studies assessing the metabolic effects of bariatric surgeries.

Bile acids (BAs) are key mediators of the glycemic control after bariatric surgeries. Cholecystectomy modifies the kinetics of BAs, and whether this procedure influences the BAs pool and its metabolic response to bariatric surgeries is not known. We used targeted and untargeted metabolomics to assess whether cholecystectomy influenced plasma and fecal BAs fluctuations and the systemic metabolomic profile after Roux-en-Y gastric bypass (RYGB). Women with obesity and type 2 diabetes were included. Sample collections and clinical evaluations were performed before and 3 months after RYGB. RYGB influenced 9 fecal and 3 plasma BAs in patients with cholecystectomy (p ≤ 0.05). Comparisons between patients with and without cholecystectomy revealed different concentrations of 4 fecal and 5 plasma BAs (p ≤ 0.05). Cholecystectomy impacted the global metabolomics responses to RYGB, and patients who underwent the gallbladder removal also lacked some significant improvements in clinical markers, primarily the lipid profile. By affecting the BAs concentrations, cholecystectomy seems to alter the systemic metabolic response to RYGB. Therefore, cholecystectomy may act as a bias in assessments of the metabolic effects of bariatric surgeries and their relationships with clinical outcomes.

Intestinal expression of toll-like receptor gene changes early after gastric bypass surgery and association with type 2 diabetes remission.

OBJECTIVES: Abnormal activation of toll-like receptors (TLRs) is observed in obese rodents and is correlated with local dysbiosis and increased gut permeability. These purported changes trigger systemic inflammation associated with obesity-related comorbidities, including type 2 diabetes (T2D). Roux-en-Y gastric bypass (RYGB) surgery is an effective treatment for severe obesity and known to induce changes in the gut microbiota and decrease systemic inflammation in humans. This study examined the intestinal expression of TLR-encoding genes in obese women (n = 20) treated with RYGB surgery and the relationship of these genes with T2D remission (T2Dr METHODS: Intestinal biopsies were performed before and 3 months after RYGB surgery. Partial and complete T2Dr after 1 year was assessed using the American Diabetes Association criteria. Affymetrix Human GeneChip 1.0 ST array (microarray) and TaqMan assay (real-time quantitative polymerase chain reaction) were used to analyze intestinal gene expression, and associations with systemic markers of energy homeostasis were examined. RESULTS: Patients experienced significant weight loss (P < 0.001) and altered gut TLR gene expression 3 months after surgery. The main effects were a reduction in jejunal TLR4 expression in patients with complete and partial T2Dr (P < 0.05). There was a postoperative decrease in jejunal TLR7 expression in patients with complete T2Dr that correlated inversely with high-density lipoprotein cholesterol and positively with triglyceride concentrations, but not with weight loss. CONCLUSIONS: RYGB-induced weight loss-independent changes in the expression of intestinal TLR-encoding genes in obese women and complete T2Dr that was correlated with systemic markers of energy homeostasis. The modulation of intestinal TLRs may mediate inflammatory mechanisms linked to T2Dr after RYGB surgery.

Potential premalignant status of gastric portion excluded after Roux en-Y gastric bypass in obese women: A pilot study.

We evaluated whether the excluded stomach (ES) after Roux-en-Y gastric bypass (RYGB) can represent a premalignant environment. Twenty obese women were prospectively submitted to double-balloon enteroscopy (DBE) with gastric juice and biopsy collection, before and 3 months after RYGB. We then evaluated morphological and molecular changes by combining endoscopic and histopathological analyses with an integrated untargeted metabolomics and transcriptomics multiplatform. Preoperatively, 16 women already presented with gastric histopathological alterations and an increased pH (≥4.0). These gastric abnormalities worsened after RYGB. A 90-fold increase in the concentration of bile acids was found in ES fluid, which also contained other metabolites commonly found in the intestinal environment, urine, and faeces. In addition, 135 genes were differentially expressed in ES tissue. Combined analysis of metabolic and gene expression data suggested that RYGB promoted activation of biological processes involved in local inflammation, bacteria overgrowth, and cell proliferation sustained by genes involved in carcinogenesis. Accumulated fluid in the ES appears to behave as a potential premalignant environment due to worsening inflammation and changing gene expression patterns that are favorable to the development of cancer. Considering that ES may remain for the rest of the patient's life, long-term ES monitoring is therefore recommended for patients undergoing RYGB.

Fecal bile acid profile after Roux-en-Y gastric bypass and its association with the remission of type 2 diabetes in obese women: A preliminary study.

OBJECTIVE: To assess the influence of Roux-en-Y gastric by-pass (RYGB) on fecal bile acid (BA) profile and its relationship with postoperative remission of type 2 diabetes (T2D). METHODS: Fecal samples were collected 3 and 12 months after RYGB from diabetic obese women who were responsive (n = 12) and non-responsive (n = 8) to postoperative remission of T2D. Fecal BA profile was accessed by liquid chromatography coupled to tandem mass spectrometry in a targeted approach. RESULTS: Relative to pre-operative levels, a total of 10 fecal BA profiles decreased after RYGB (ANOVA, p ≤ 0.05) with significant fold-changes for glycochenodeoxycholic, glycocholic, taurocholic, and taurochenodeoxycholic acids at 3-months postoperatively, and for glycochenodeoxycholic, glycocholic and taurocholic acids at 12 months postoperatively (Benjamini-Hochberg, p ≤ 0.05). Postoperative changes in fecal BA were different between responsive and non-responsive women, with a significant reduction in more sub-fractions of BA in responsive women than in non-responsive women, and a marked difference in the temporal behavior of cholic acid (CA) and chenodeoxycholic acid (CDCA), thus reflecting changes in CA/CDCA ratio, and tauroursodeoxycolic (TUDCA) levels between these responsiveness groups (ANOVA, p ≤ 0.05). CONCLUSION: RYGB induces a marked reduction in the concentration of fecal BA, which is heterogeneous according to T2D responsiveness.

Reduced intestinal FADS1 gene expression and plasma omega-3 fatty acids following Roux-en-Y gastric bypass.

BACKGROUND & AIMS: Roux-en-Y gastric bypass (RYGB) limits food ingestion and may alter the intestinal expression of genes involved in the endogenous synthesis of polyunsaturated fatty acids (PUFAs). These changes may decrease the systemic availability of bioactive PUFAs after RYGB. To study the impact of RYGB on the dietary ingestion and plasma concentration of PUFAs and on the intestinal expression of genes involved in their endogenous biosynthesis in severely obese women with type 2 diabetes. METHODS: Before, and 3 and 12 months after RYGB, obese women (n = 20) self-reported a seven-day dietary record, answered a food frequency query and provided plasma samples for alpha-linolenic (ALA), eicosapentaenoic (EPA), docosahexaenoic (DHA) and arachidonic (ARA) acid assessment by gas chromatography. Intestinal biopsies (duodenum, jejunum and ileum) were collected through double-balloon endoscopy before and 3 months after RYGB for gene expression analysis by microarray (Human GeneChip 1.0 ST array) and RT-qPCR validation. RESULTS: Compared to the preoperative period, patients had decreased intakes of PUFAs, fish and soybean oil (p < 0.05) and lower plasma concentrations of ALA and EPA (p < 0.001) 3 and 12 months after RYGB. FADS1 gene expression was lower in duodenum (RT-qPCR fold change = -1.620, p < 0.05) and jejunum (RT-qPCR fold change = -1.549, p < 0.05) 3 months following RYGB, compared to before surgery. CONCLUSION: RYGB decreased PUFA ingestion, plasma ALA and EPA levels, and intestinal expression of FADS1 gene. The latter encodes a key enzyme involved in endogenous biosynthesis of PUFAs. These data suggest that supplementation of omega-3 PUFAs may be required for obese patients undergoing RYGB. Clinical Trial Registry number and website: www.clinicaltrials.gov - NCT01251016; Plataforma Brasil - 19339913.0.0000.0068.

The SURMetaGIT study: Design and rationale for a prospective pan-omics examination of the gastrointestinal response to Roux-en-Y gastric bypass surgery.

Objective To describe the protocol of the SURgically induced Metabolic effects on the Human GastroIntestinal Tract (SURMetaGIT) study, a clinical pan-omics study exploring the gastrointestinal tract as a central organ driving remission of type 2 diabetes mellitus (T2DM) after Roux-en-Y gastric bypass (RYGB). The main points considered in the study's design and challenges faced in its application are detailed. Methods This observational, longitudinal, prospective study involved collection of gastrointestinal biopsy specimens, faeces, urine, and blood from 25 obese women with T2DM who were candidates for RYGB (20 patients for omics assessment and 5 for omics validation). These collections were performed preoperatively and 3 and 24 months postoperatively. Gastrointestinal transcriptomics; faecal metagenomics and metabolomics; plasma proteomics, lipidomics, and metabolomics; and biochemical, nutritional, and metabolic data were assessed to identify their short- and long-term correlations with T2DM remission. Results Data were collected from 20 patients before and 3 months after RYGB. These patients have nearly completed the 2-year follow-up assessments. The five additional patients are currently being selected for omics data validation. Conclusion The multi-integrated pan-omics approach of the SURMetaGIT study enables integrated analysis of data that will contribute to the understanding of molecular mechanisms involved in T2DM remission after RYGB.