Marco Anselmino

Roux-en-Y Gastric Bypass and Sleeve Gastrectomy: Mechanisms of Diabetes Remission and Role of Gut Hormones

CONTEXT In obese patients with type 2 diabetes (T2DM), Roux-en-Y-gastric-bypass (RYGB) and sleeve gastrectomy (SLG) improve glycemic control. OBJECTIVE The objective of this study was to investigate the mechanisms of surgery-induced T2DM improvement and role of gastrointestinal hormones. PATIENTS, SETTING, AND INTERVENTION: In 35 patients with T2DM, we performed a mixed-meal test before and 15 days and 1 year after surgery (23 RYGB and 12 SLG). MAIN OUTCOME MEASURES Insulin sensitivity, β-cell function, and amylin, ghrelin, PYY, pancreatic polypeptide (PP), glucagon, and glucagon-like peptide-1 (GLP-1) responses to the meal were measured. RESULTS T2DM remission occurred in 13 patients undergoing RYGB and in 7 patients undergoing SLG. Similarly in the RYGB and SLG groups, β-cell glucose sensitivity improved both early and long term (P < .005), whereas insulin sensitivity improved long term only (P < .006), in proportion to body mass index changes (P < .001). Early after RYGB, glucagon and GLP-1 responses to the meal increased, whereas the PP response decreased. At 1 year, PYY was increased, and PP, amylin, ghrelin, and GLP-1 were reduced. After SLG, hormonal responses were similar to those with RYGB except that PP was increased, whereas amylin was unchanged. In remitters, fasting GLP-1 was higher (P = .04), but its meal response was flat compared with that of nonremitters; postsurgery, however, the GLP-1 response was higher. Other hormone responses were similar between the 2 groups. In logistic regression, presurgery β-cell glucose sensitivity (positive, P < .0001) and meal-stimulated GLP-1 response (negative, P = .004) were the only predictors of remission. CONCLUSIONS RYGB and SLG have a similar impact on diabetes remission, of which baseline β-cell glucose sensitivity and a restored GLP-1 response are the chief determinants. Other hormonal responses are the consequences of the altered gastrointestinal anatomy.

The Role of beta-Cell Function and Insulin Sensitivity in the Remission of Type 2 Diabetes after Gastric Bypass Surgery

CONTEXT Bariatric surgery can induce remission in a high proportion of severely obese patients with type 2 diabetes mellitus (T2DM). OBJECTIVE Our objective was to investigate predictors and mechanisms of surgery-induced diabetes remission. PATIENTS AND SETTING Forty-three morbidly obese subjects (body mass index = 45.6 ± 5.0 kg/m(2)), 32 with T2DM and 11 nondiabetic [normal glucose tolerance (NGT)], participated at a clinical research center. INTERVENTION Patients underwent Roux-en-Y gastric bypass. MAIN OUTCOME MEASURES Diabetes remission and β-cell function were evaluated. RESULTS Subjects were tested before and 45 d and 1 yr after surgery. Weight decreased similarly in T2DM and NGT (-39 kg at 1 yr, P < 0.0001). Insulin sensitivity improved in both groups in proportion to the changes in body mass index but remained lower in T2DM than NGT (386 ± 91 vs. 479 ± 89 ml/min · m(2), P < 0.01). Based on glycosylated hemoglobin and oral glucose testing, diabetes had remitted in nine patients at 45 d and in an additional 16 at 1 yr. In T2DM, β-cell glucose sensitivity increased early after surgery but was no further improved and still abnormal at 1 yr [median, 48 (coefficient interval, 53) pmol/min · m(2) · mm vs. median, 100 (coefficient interval, 68) of NGT, P < 0.001]. Baseline β-cell glucose sensitivity was progressively worse in early remitters, late remitters, and nonremitters (median, 54[coefficient interval, 50] vs. median, 22[coefficient interval, 26] vs. median, 4[coefficient interval, 10] pmol/min · m(2) · mm) and, by logistic regression, was the only predictor of failure [odds ratio for bottom tertile = 7.9 (95% confidence interval = 1.2-51.9); P = 0.03]. CONCLUSIONS In morbid obesity, Roux-en-Y gastric bypass causes rapid and profound metabolic adaptations; insulin sensitivity improves in proportion to the weight loss, and β-cell glucose sensitivity increases independently of weight loss. Over a period of 1 yr after surgery, diabetes remission depends on the starting degree of β-cell dysfunction.

Vascular Generation of Tumor Necrosis Factor-α Reduces Nitric Oxide Availability in Small Arteries From Visceral Fat of Obese Patients

OBJECTIVES The aim of this study was to assess whether small arteries from visceral fat of obese patients show a reduced nitric oxide (NO)-dependent relaxation, as compared with lean control subjects, focusing on the role of the pro-inflammatory cytokine tumor necrosis factor (TNF)-α. BACKGROUND Visceral obesity is characterized by endothelial dysfunction. METHODS Small arteries from 14 obese (body mass index 48.4 ± 11 kg/m(2)) and 14 control subjects (body mass index 24.9 ± 2 kg/m(2)), dissected after a visceral fat biopsy (laparoscopy), were evaluated on a pressurized micromyograph. Endothelium-dependent relaxation was assessed by acetylcholine. The NO availability, superoxide production, and inflammation were assessed by testing acetylcholine under the nitric oxide synthase (NOS) inhibitor N(ω)-nitro-L-arginine methylester, tempol (superoxide scavenger), and infliximab (monoclonal anti-TNF-α antibody), respectively. The roles of nicotinamide adenine dinucleotide phosphate oxidase and inducible nitric oxide synthase (iNOS) were assessed by their selective inhibitors apocynin and S-methylisothiourea (SMT), respectively. Vascular superoxide generation (dihydroethidium staining) protein expression of TNF-α and NOS isoforms (Western Blot) and TNF-α localization (immunohistochemistry) were assessed. RESULTS Vessels from obese patients displayed a blunted relaxation to acetylcholine and a reduced inhibitory effect of N(ω)-nitro-L-arginine methylester. These alterations were normalized by tempol or infliximab while being partly ameliorated by apocynin and SMT. Vascular superoxide generation was increased (p < 0.01) in obese patients. This condition was abrogated by both tempol and infliximab and partly (p < 0.05 vs. control subjects) reduced by apocynin or SMT. Enhanced TNF-α and iNOS expression together with increased TNF-α localization in the vascular media were detected. CONCLUSIONS Small arteries from visceral fat of obese patients are characterized by an increased TNF-α production, which reduces NO availability by promoting superoxide generation via nicotinamide adenine dinucleotide phosphate oxidase and iNOS activation.

Long-Term Effects of Bariatric Surgery on Meal Disposal and β-Cell Function in Diabetic and Nondiabetic Patients

Gastric bypass surgery leads to marked improvements in glucose tolerance and insulin sensitivity in obese type 2 diabetes (T2D); the impact on glucose fluxes in response to a physiological stimulus, such as a mixed meal test (MTT), has not been determined. We administered an MTT to 12 obese T2D patients and 15 obese nondiabetic (ND) subjects before and 1 year after surgery (10 T2D and 11 ND) using the double-tracer technique and modeling of β-cell function. In both groups postsurgery, tracer-derived appearance of oral glucose was biphasic, a rapid increase followed by a sharp drop, a pattern that was mirrored by postprandial glucose levels and insulin secretion. In diabetic patients, surgery lowered fasting and postprandial glucose levels, peripheral insulin sensitivity increased in proportion to weight loss (∼30%), and β-cell glucose sensitivity doubled but did not normalize (compared with 21 nonsurgical obese and lean controls). Endogenous glucose production, however, was less suppressed during the MMT as the combined result of a relative hyperglucagonemia and the rapid fall in plasma glucose and insulin levels. We conclude that in T2D, bypass surgery changes the postprandial response to a dumping-like pattern and improves glucose tolerance, β-cell function, and peripheral insulin sensitivity but worsens endogenous glucose output in response to a physiological stimulus.

Expression of thyrotropin and thyroid hormone receptors in adipose tissue of patients with morbid obesity and/or type 2 diabetes: effects of weight loss

Objective:Increased thyroid-stimulating hormone (TSH) and FT3 levels are often found in clinically euthyroid obese individuals. Information on thyroid gene expression in human adipose tissue is scarce. The objective of this study was to measure the expression of the TSH receptor (TSHR) and the thyroid hormone receptor (TRα1) genes in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) in obese individuals and to test the effect of weight loss on these genes.Study Design and Participants:This study is a prospective study involving 107 obese (body mass index (BMI)=46±8 kg m−2, 52 with type 2 diabetes or impaired glucose tolerance) and 12 lean nondiabetic participants. A total of 27 obese patients were restudied 1 year after gastric bypass surgery. Total RNA was extracted from SAT and VAT obtained at baseline from all participants, and from SAT in obese patients post surgery.Results:Circulating TSH and FT3 levels were 170 and 36%, respectively, higher in obese patients than in controls. In SAT, TSHR and TRα1 were reduced in the obese by 67 and 33%, respectively, regardless of glucose tolerance. A similar trend was found in VAT. Post surgery, a BMI decrease of 33% was associated with a decrease in TSH and FT3 levels and with a 150 and 70% increase in SAT of TSHR and TRα1, respectively.Conclusion:In both subcutaneous and visceral fat, the thyroid gene expression (especially TSHR) is reduced in obesity. The reversal of these changes with major weight loss and the reciprocal changes in plasma TSH and FT3 levels suggest a role for adipocytes in the regulation of TSH and thyroid hormones.

Tumour necrosis factor-alpha participates on the endothelin-1/nitric oxide imbalance in small arteries from obese patients: role of perivascular adipose tissue

AIMS We assessed the impact of vascular and perivascular tumour necrosis factor-alpha (TNF-α) on the endothelin (ET)-1/nitric oxide (NO) system and the molecular pathways involved in small arteries from visceral fat of obese patients (Obese) and Controls. METHODS AND RESULTS Isolated small arteries from 16 Obese and 14 Controls were evaluated on a pressurized micromyograph. Endogenous ET-1 activity was assessed by the ETA blocker BQ-123. TNF-α and NO were tested by anti-TNF-α infliximab (IFX) and N(ω)-nitro-l-arginine methylester (L-NAME). Gene and protein expression of TNF-α, ET-1, ETA, and ETB receptors were determined by RT-PCR and IHC on arterial wall and in isolated adipocytes. Obese showed a blunted L-NAME-induced vasoconstriction, which was potentiated by IFX, and an increased relaxation to BQ-123, unaffected by L-NAME but attenuated by IFX. Perivascular adipose tissue (PVAT) removal reversed these effects. Obese showed intravascular superoxide excess, which was decreased by apocynin (NAD(P)H oxidase inhibitor), L-NAME, and BQ-123 incubations, and abolished by IFX. An increased vascular expression of ET-1, ETA, and ETB receptors, and higher vascular/perivascular TNF-α and TNF-α receptor expression were also detected. The arterial expression and phosphorylation of c-Jun N-terminal kinase (JNK) were higher in Obese vs. Controls, and downregulated by IFX. CONCLUSIONS In small arteries of Obese, PVAT-derived TNF-α excess, and an increased vascular expression of ET-1 and ETA receptor, contribute to the ET-1/NO system imbalance, by impairing tonic NO release. Reactive oxygen species excess, via NAD(P)H oxidase activation, induces the endothelial nitric oxide synthase uncoupling, which in turn generates superoxide and impairs NO production. The up-regulated JNK pathway represents a crucial molecular signalling involved in this process.

Clinical Evaluation of Fibrin Glue in the Prevention of Anastomotic Leak and Internal Hernia after Laparoscopic Gastric Bypass: Preliminary Results of a Prospective, Randomized Multicenter Trial

Background: Gastro-jejunal anastomotic leak and internal hernia can be life-threatening complications of laparoscopic Roux-en-Y gastric bypass (LRYGBP), ranging from 0.1-4.3% and from 0.8-4.5% respectively. The safety and efficacy of a fibrin glue (Tissucol®) was assessed when placed around the anastomoses and over the mesenteric openings for prevention of anastomotic leaks and internal hernias after LRYGBP. Methods: A prospective, randomized, multicenter, clinical trial commenced in January 2004. Patients with BMI 40-59 kg/m2, aged 21-60 years, undergoing LRYGBP, were randomized into: 1) study group (fibrin glue applied on the gastro-jejunal and jejuno-jejunal anastomoses and the mesenteric openings); 2) control group (no fibrin glue, but suture of the mesenteric openings). 322 patients, 161 for each arm, will be enrolled for an estimated period of 24 months. Sex, age, operative time, time to postoperative oral diet and hospital stay, early and late complications rates are evaluated. An interim evaluation was conducted after 15 months. Results: To April 2005, 204 patients were randomized: 111 in the control group (mean age 39.0±11.6 years, BMI 46.4±8.2) and 93 in the fibrin glue group (mean age 42.9±11.7 years, BMI 46.9±6.4). There was no mortality or conversion in both groups; no differences in operative time and postoperative hospital stay were recorded. Time to postoperative oral diet was shorter for the fibrin glue group (P=0.0044). Neither leaks nor internal hernias have occurred in the fibrin glue group. The incidence of leaks (2 cases, 1.8%) and the overall reoperation rate were higher in the control group (P=0.0165). Conclusion: The preliminary results suggest that Tissucol® application has no adverse effects, is not time-consuming, and may be effective in preventing leaks and internal hernias in morbidly obese patients undergoing LRYGBP.

Human leptin tissue distribution, but not weight loss-dependent change in expression, is associated with methylation of its promoter.

Leptin is a master regulator of energy homeostasis. Its expression, prevalently localized in adipocytes, is positively related to adipose mass. Epigenetics is emerging as an important contributor to the changes in gene expression undergone by adipose tissue during obesity. We herein investigated the involvement of methylation-dependent mechanisms in leptin regulation in humans. We studied the methylation profile of a 305 bp region in the leptin promoter and analyzed the correspondent leptin expression in visceral adipocyte fraction (AF) and stromal vascular fraction (SVF) of white adipose tissue (WAT) and liver. We found an inverse relationship between methylation and leptin expression with AF displaying a lower methylation density (8%) than SVF and liver (18%, 21%). We evidenced a hot spot region, which mostly differentiates AF versus liver. This includes C15 and 21, which are within the recognition sequences for the transcription factors Sp1 and C/EBP, and C22-23/24, flanking a TATA box. In vitro studies demonstrated that demethylation (by decitabine) increase or de novo activate leptin expression in primary fibroblasts and HeLa cells, respectively. A longitudinal study carried out in patients analyzed before and after bariatric surgery-induced weight loss indicated that in this case decrease in WAT leptin expression (about 50%) does not correspond to changes in promoter methylation density. In conclusion, methylation density in the leptin promoter constitutes one control level for cell type specific leptin expression, whereas weight-loss induced changes in leptin expression does not seem to be methylation-dependent.

Pattern of expression of adiponectin receptors in human adipose tissue depots and its relation to the metabolic state

Objective:To investigate whether adiponectin receptor genes (AdipoR1 and AdipoR2) expression in human subcutaneous (SAT) and visceral (VAT) adipose tissue in severely obese patients with or without diabetes is related to adiponectin gene (APM1) expression and in vivo metabolic parameters.Design:Cross-sectional, clinical research study.Subjects:Total RNA was extracted from SAT and VAT tissue obtained during surgery from 13 lean controls, 30 obese diabetic patients, 19 obese glucose-intolerant patients and 54 obese subjects with normal glucose tolerance.Measurements:Tissue expression of APM1, AdipoR1 and AdipoR2, tissue concentration of adiponectin (ApN), and metabolic variables.Results:APM1 expression was higher in SAT than VAT (1.06±0.76 vs 0.69±0.52, P<0.0001) as was AdipoR1 (1.17±0.70 vs 0.66±0.38, P<0.0001) and AdipoR2 (7.02±6.19 vs 0.75±0.64, P<0.0001). In SAT, APM1 and AdipoR1 expression tended to be lower – by 0.38±0.22 and 0.35±0.22, respectively – and AdipoR2 expression was markedly depressed – by 4.82±1.93 – in association with obesity, whereas presence of diabetes had no additional effect. In VAT, APM1 and AdipoR1 expressions were also reduced – by 0.36±0.16 and 0.30±0.11, respectively – in association with obesity. Within both SAT and VAT, expression levels of APM1, AdipoR1 and AdipoR2 were all positively interrelated. Tissue ApN concentrations in SAT were similar across groups, whereas ApN levels in VAT were substantially lower in association with obesity (by an average of 63±12 ng/mg total protein, P<0.0001). In multivariate models adjusting for sex, age and obesity, serum triglyceride concentrations were reciprocally related to APM1 (r=−0.27, P<0.02), AdipoR1 (r=−0.37, P<0.002 and AdipoR2 expression (r=−0.37, P<0.002) in VAT. Likewise, plasma insulin concentrations were inversely related only to APM1 in VAT (r=−0.25, P<0.03).Conclusions:Severe obesity is associated with suppressed expression of both ApN and its receptors in both SAT and VAT, the expression levels in VAT are specifically linked with hyperinsulinemia and dyslipidemia.

Effects of Bariatric Surgery on Early Myocardial Alterations in Adult Severely Obese Subjects

Objective: Aim of this study was to investigate the effect of weight loss on structural and functional myocardial alterations in severely obese subjects treated with bariatric surgery. Patients and Methods: Thirteen severely obese patients (2 males and 11 females) were enrolled in the study. All subjects underwent conventional 2D color Doppler echocardiography. The new ultrasonic techniques used were: (a) integrated backscatter for the analysis of myocardial reflectivity, referred to pericardial interface as expression of myocardial structure (increase in collagen content) and of cyclic variation index as expression of intrinsic myocardial contractility and (b) color Doppler myocardial imaging (CDMI) for the analysis of strain and strain rate (myocardial deformability). All subjects underwent bariatric surgery and were resubmitted to echocardiographic and biochemical examination 6–24 months after surgery. Results: The main finding of the present study was a quite complete normalization of myocardial functional and structural alterations after weight loss. In particular, the cyclic variation index at septum level improved from 14.6 ± 7.0 before to 25.7 ± 11.2 (means ± SD) after surgery (controls: 36.2 ± 9.1). Mean reflectivity at septum level significantly decreased from 55.8 ± 9.5 to 46.5 ± 8.8 (controls: 43.0 ± 8.0). Also, the strain at septum level significantly improved after surgery (from –11.9 ± 3.2 to –20.4 ± 5.3; controls: –23.4 ± 9). Conclusion: This study establishes: (a) the utility of new ultrasonic techniques to detect very early structural and functional myocardial alterations in severely obese patients, and (b) the regression of these subclinical abnormalities after weight loss achieved by bariatric surgery.