Metabolic surgery-induced changes of the growth hormone system relate to improved adipose tissue function.

AIMS: Body weight loss improves insulin resistance and growth hormone secretion in obesity, which may be regulated by leptin according to preclinical studies. How changes in leptin, lipids and insulin sensitivity after bariatric (metabolic) surgery affect the human growth hormone system is yet unclear. PARTICIPANTS AND METHODS: People with obesity (OBE, n = 79, BMI 50.8 ± 6.3 kg/m2) were studied before, 2, 12, 24 and 52 weeks after metabolic surgery and compared to lean healthy humans (control; CON, n = 24, BMI 24.3 ± 3.1 kg/m2). Tissue-specific insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamps with D-[6,6-2H2]glucose. Fasting leptin, growth hormone (GH), insulin-like growth factor 1 (IGF-1) and IGF-binding proteins (IGFBP1, IGFBP3) were measured using ELISA. RESULTS: At baseline, OBE exhibited higher glycemia and leptinemia as well as pronounced peripheral, adipose tissue and hepatic insulin resistance compared to CON. GH and IGFBP1 were lower, while IGF1 was comparable between groups. At 52 weeks, OBE had lost 33% body weight and doubled their peripheral insulin sensitivity, which was paralleled by continuous increases in GH, IGF-1 and IGFBP1 as well as decrease in leptin. The rise in GH correlated with reductions in free fatty acids, adipose tissue insulin resistance and insulinemia, but not with changes in body weight, peripheral insulin sensitivity, glycemia or leptinemia. The rise in IGF-1 correlated with reduction in high-sensitive C-reactive protein. CONCLUSION: Reversal of alterations of the GH-IGF-1 axis after surgically-induced weight loss is unlikely related to improved leptin secretion and/or insulin sensitivity, but is rather associated with restored adipose tissue function and reduced low-grade inflammation.

Mitochondrial respiration is decreased in visceral but not subcutaneous adipose tissue in obese individuals with fatty liver disease.

BACKGROUND & AIMS: Adipose tissue dysfunction is involved in the development of insulin resistance and is responsible for excessive lipid delivery to other organs such as the liver. We tested the hypothesis that impaired mitochondrial function is a common feature of subcutaneous (SAT) and visceral adipose tissue (VAT), but may differently contribute to adipose tissue insulin resistance (IR) in obesity, non-alcoholic fatty liver (NAFL) and steatohepatitis (NASH). METHODS: In this cross-sectional study, we analyzed tissue-specific insulin sensitivity using stable isotope dilution and hyperinsulinemic-normoglycemic clamp tests. We also assessed mitochondrial respiration, mRNA and protein expression, and tissue morphology in biopsies of SAT and VAT from obese humans without NAFL, with NAFL or with NASH (n = 22/group). RESULTS: Compared to individuals without liver disease, persons with NAFL and NASH had about 30% (p = 0.010) and 33% (p = 0.002) lower maximal mitochondrial respiration, respectively, in VAT, but not in SAT. The lower maximal mitochondrial respiration of VAT was associated with lower adipose tissue insulin sensitivity (ß = 0.985, p = 0.041) and with increased VAT protein expression of tumor necrosis factor A across all groups (ß = -0.085, p = 0.040). VAT from individuals with NASH was characterized by lower expression of oxidative phosphorylation complex IV (p = 0.042) and higher mRNA expression of the macrophage marker CD68 (p = 0.002) than VAT from participants without NAFL. CONCLUSIONS: Humans with non-alcoholic fatty liver disease have distinct abnormalities of VAT energy metabolism, which correlate with adipose tissue dysfunction and may favor progression of NAFL to NASH. LAY SUMMARY: Adipose tissue (commonly called body fat) can be found under the skin (subcutaneous) or around internal organs (visceral). Dysfunction of adipose tissue can cause insulin resistance and lead to excess delivery of fat to other organs such as the liver. Herein, we show that dysfunction specifically in visceral adipose tissue was associated with fatty liver disease. CLINICAL TRIAL NUMBER: NCT01477957.

Comparative efficacy and safety of the duodenal-jejunal bypass liner in obese patients with type 2 diabetes mellitus: A case control study.

AIMS: The duodenal-jejunal bypass liner (DJBL) is an endoscopic device mimicking surgical duodenal-jejunal bypass, and is indicated for the treatment of obesity-associated type 2 diabetes mellitus. This analysis was conducted to evaluate the efficacy and safety of the DJBL in comparison to lifestyle changes and antidiabetic drugs. MATERIALS AND METHODS: To determine the efficacy and long-term safety of the DJBL, data concerning 235 obese patients with type 2 diabetes mellitus from the German DJBL registry were analysed. For comparison with standard treatment, propensity-score-matching with patients from the German DPV registry, including the matching parameters sex, age, diabetes duration, baseline BMI and baseline HbA1c, was applied. The final matched cohort consisted of 111 patients in the DJBL group and 222 matched control DPV patients. RESULTS: Mean treatment time with the DJBL was 47.5 ± 12.2 weeks, mean BMI reduction was 5.0 kg/m2 (P < .001) and mean HbA1c reduction was 1.3% (11.9 mmol/mol) (P < .001). Reduction of antidiabetic medications and improvements in other metabolic and cardiovascular risk parameters was observed. In comparison to the matched control group, mean reductions in HbA1c (-1.37% vs -0.51% [12.6 vs 3.2 mmol/mol]; P < .0001) and BMI (-3.02 kg/m2 vs -0.39 kg/m2 ; P < .0001) were significantly higher. Total cholesterol, LDL cholesterol and blood pressure were also significantly better. CONCLUSION: This study provides the largest, so far, hypothesis-generating evidence for a putative positive risk/benefit ratio for treatment of obese patients with type 2 diabetes mellitus with the DJBL as an alternative treatment option for this patient population.

Loss of mitochondrial adaptation associates with deterioration of mitochondrial turnover and structure in metabolic dysfunction-associated steatotic liver disease.

BACKGROUND: Obesity and type 2 diabetes frequently have metabolic dysfunction-associated steatotic liver disease (MASLD) including steatohepatitis (MASH). In obesity, the liver may adapt its oxidative capacity, but the role of mitochondrial turnover in MASLD remains uncertain. METHODS: This cross-sectional study compared individuals with class III obesity (n = 8/group) without (control, OBE CON; NAFLD activity score: 0.4 ± 0.1) or with steatosis (OBE MASL, 2.3 ± 0.4), or MASH (OBE MASH, 5.3 ± 0.3, p < 0.05 vs. other groups). Hepatic mitochondrial ultrastructure was assessed by transmission electron microscopy, mitochondrial respiration by high-resolution respirometry, biomarkers of mitochondrial quality control and endoplasmic reticulum (ER) stress by Western Blot. RESULTS: Mitochondrial oxidative capacity was 31 % higher in OBE MASL, but 25 % lower in OBE MASH (p < 0.05 vs. OBE CON). OBE MASH showed ~1.5fold lower mitochondrial number, but ~1.2-1.5fold higher diameter and area (p < 0.001 vs. other groups). Biomarkers of autophagy (p62), mitophagy (PINK1, PARKIN), fission (DRP-1, FIS1) and fusion (MFN1/2, OPA1) were reduced in OBE MASH (p < 0.05 vs. OBE CON). OBE MASL showed lower p62, p-PARKIN/PARKIN, and p-DRP-1 (p < 0.05 vs. OBE CON). OBE MASL and MASH showed higher ER stress markers (PERK, ATF4, p-eIF2α-S51/eIF2α; p < 0.05 vs. OBE CON). Mitochondrial diameter associated inversely with fusion/fission biomarkers and with oxidative capacity, but positively with H2O2. CONCLUSION: Humans with hepatic steatosis already exhibit impaired mitochondrial turnover, despite upregulated oxidative capacity, and evidence for ER stress. In MASH, oxidative stress likely mediates progressive decline of mitochondrial turnover, ultrastructure and respiration indicating that mitochondrial quality control is key for energy metabolism and may have potential for targeting MASH. ClinGovTrial:NCT01477957.

Impaired Hepatic Mitochondrial Capacity in Nonalcoholic Steatohepatitis Associated With Type 2 Diabetes.

OBJECTIVE: Individuals with type 2 diabetes are at higher risk of progression of nonalcoholic fatty liver (steatosis) to steatohepatitis (NASH), fibrosis, and cirrhosis. The hepatic metabolism of obese individuals adapts by upregulation of mitochondrial capacity, which may be lost during the progression of steatosis. However, the role of type 2 diabetes with regard to hepatic mitochondrial function in NASH remains unclear. RESEARCH DESIGN AND METHODS: We therefore examined obese individuals with histologically proven NASH without (OBE) (n = 30; BMI 52 ± 9 kg/m2) or with type 2 diabetes (T2D) (n = 15; 51 ± 7 kg/m2) as well as healthy individuals without liver disease (CON) (n = 14; 25 ± 2 kg/m2). Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamps with d-[6,6-2H2]glucose. Liver biopsies were used for assessing mitochondrial capacity by high-resolution respirometry and protein expression. RESULTS: T2D and OBE had comparable hepatic fat content, lobular inflammation, and fibrosis. Oxidative capacity in liver tissue normalized for citrate synthase activity was 59% greater in OBE than in CON, whereas T2D presented with 33% lower complex II-linked oxidative capacity than OBE and higher H2O2 production than CON. Interestingly, those with NASH and hepatic fibrosis score ≥1 had lower oxidative capacity and antioxidant defense than those without fibrosis. CONCLUSIONS: Loss of hepatic mitochondrial adaptation characterizes NASH and type 2 diabetes or hepatic fibrosis and may thereby favor accelerated disease progression.

Major histocompatibility complex class I-related chains A and B (MIC A/B): a novel role in nonalcoholic steatohepatitis.

UNLABELLED: Stress-induced soluble major histocompatibility complex class I-related chains A/B (MIC A/B) are increased in chronic liver diseases and hepatocellular malignancy. We investigated the impact of these molecules on liver injury, apoptosis, and fibrosis in nonalcoholic steatohepatitis (NASH). Blood and liver tissue were obtained from 40 patients with NASH undergoing bariatric surgery for obesity. The control group consisted of 10 healthy individuals. We also investigated 10 patients with nonalcoholic fatty liver (NAFL). Polymerase chain reaction was used to measure messenger RNA (mRNA) transcripts of MIC A/B, natural killer cell receptor G2D (NKG2D), CD95/Fas, and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-death receptor 5 (DR5). Apoptosis was quantified by way of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) (intrahepatic) and M30/M65 (systemic). Liver injury was assessed histopathologically and serologically (alanine aminotransferase/aspartate aminotransferase). Fibrosis was identified by Sirius red staining, quantitative morphometry, and alpha-smooth muscle actin and collagen 1alpha transcripts. Compared with controls, patients with NASH revealed significant increases in (1) NKG2D mRNA (13.1-fold) and MIC A/B mRNA (3.6-fold and 15.8-fold, respectively); (2) TRAIL-DR5 and CD95/Fas mRNA (2.7-fold and 3.6-fold, respectively); (3) TUNEL-positive hepatocytes (4.0-fold); and (4) M30 and M65 levels (4.6-fold and 3.4-fold, respectively). We found relevant correlations between MIC protein expression rates and NAS and fibrosis stages. In contrast, NKG2D and MIC A/B transcripts were attenuated in patients with NAFL compared with NASH. Histopathologically, NASH patients revealed increased NAS scores, an accumulation of natural killer cells, and 2.7-fold increased hepatic fibrosis by quantitative morphometry. CONCLUSION: Our findings suggest an important role for MIC A/B in liver injury. Therapeutic intervention aimed at reducing MIC A/B levels may beneficially affect the progression of NASH.

Role of ceramide-to-dihydroceramide ratios for insulin resistance and non-alcoholic fatty liver disease in humans.

INTRODUCTION: Sphingolipid accumulation has been linked to obesity, type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). A recent study showed that depletion of dihydroceramide desaturase-1 (DES-1) in adipose and/or liver tissue decreases ceramide-to-dihydroceramide ratios (ceramide/dihydroceramide) in several tissues and improves the metabolic profile in mice. We tested the hypothesis that ceramide/dihydroceramide would also be elevated and relate positively to liver fat content and insulin resistance in humans. RESEARCH DESIGN AND METHODS: Thus, we assessed total and specific ceramide/dihydroceramide in various biosamples of 7 lean and 21 obese volunteers without or with different NAFLD stages, who were eligible for abdominal or bariatric surgery, respectively. Biosamples were obtained from serum, liver, rectus abdominis muscle as well as subcutaneous abdominal and visceral adipose tissue during surgery. RESULTS: Surprisingly, certain serum and liver ceramide/dihydroceramide ratios were reduced in both obesity and non-alcoholic steatohepatitis (NASH) and related inversely to liver fat content. Specifically, hepatic ceramide/dihydroceramide (species 16:0) related negatively to hepatic mitochondrial capacity and lipid peroxidation. In visceral adipose tissue, ceramide/dihydroceramide (species 16:0) associated positively with markers of inflammation. CONCLUSION: These results failed to confirm the relationships of ceramide/dihydroceramide in humans with different degree of insulin resistance. However, the low hepatic ceramide/dihydroceramide favor a role for dihydroceramide accumulation in NASH, while a specific ceramide/dihydroceramide ratio in visceral adipose tissue suggests a role of ceramides in obesity-associated low-grade inflammation.

Dynamic changes of muscle insulin sensitivity after metabolic surgery.

The mechanisms underlying improved insulin sensitivity after surgically-induced weight loss are still unclear. We monitored skeletal muscle metabolism in obese individuals before and over 52 weeks after metabolic surgery. Initial weight loss occurs in parallel with a decrease in muscle oxidative capacity and respiratory control ratio. Persistent elevation of intramyocellular lipid intermediates, likely resulting from unrestrained adipose tissue lipolysis, accompanies the lack of rapid changes in insulin sensitivity. Simultaneously, alterations in skeletal muscle expression of genes involved in calcium/lipid metabolism and mitochondrial function associate with subsequent distinct DNA methylation patterns at 52 weeks after surgery. Thus, initial unfavorable metabolic changes including insulin resistance of adipose tissue and skeletal muscle precede epigenetic modifications of genes involved in muscle energy metabolism and the long-term improvement of insulin sensitivity.

Trends in BMI, Glycemic Control and Obesity-Associated Comorbidities After Explantation of the Duodenal-Jejunal Bypass Liner (DJBL).

BACKGROUND: A novel-approach for treatment of obesity and diabetes mellitus type 2 (T2DM) is represented by the endoscopic duodenal-jejunal bypass liner (DJBL). Recent data from the German DJBL registry provide evidence for substantial efficacy of the DJBL during the implantation period in obese patients with T2DM. However, little is known about the trends of glycemic control, BMI, and comorbidities after explantation of the DJBL, which have been investigated in the registry in this report. METHODS: Patients were selected from the registry if they had a dataset at implantation, explantation, and at least one time point after explantation of the DJBL (n = 77). We also investigated a subgroup of patients with available data at least 1 year (-2 weeks) after explantation of the DJBL (n = 32). RESULTS: For a mean BMI at implantation and a mean follow-up period, an increase of BMI of 2.1 kg/m2 (CI 0.8-3.2; p = 0.013) had to be expected (for HbA1c 0.3% (CI - 0.0-0.7; p = n.s.), respectively). In the subgroup analysis, HbA1c and BMI increased after explantation of the DJBL but stayed significantly below baseline levels. Meanwhile, the mean number of antidiabetic drugs slightly increased. There was deterioration seen for blood pressure and LDL cholesterol over the postexplantation period to approximately baseline levels (or higher). CONCLUSION: With this data, we show that improvement of HbA1c and BMI can be partly maintained over a time of nearly 1-year postexplantation of the DJBL. However, for HbA1c, this may be biased by intensified medical treatment and effects deteriorated with time after explantation. These results suggest that implantation of the DJBL needs to be integrated in a long-term weight management program as most of other interventions in obese patients with T2DM. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02731859.

Longitudinal evaluation of efficacy, safety and nutritional status during one-year treatment with the duodenal-jejunal bypass liner.

BACKGROUND: The endoscopic duodenal-jejunal bypass liner (DJBL) represents a novel temporary endoscopic approach for treatment of obesity-associated type 2 diabetes. Recent results from the German DJBL registry confirmed substantial positive metabolic effects of the DJBL in type 2 diabetes. However, the last Food and Drug Administration trial was stopped due to a high occurrence of hepatic abscesses (3.5%). OBJECTIVES: Here, we analyzed time courses of development of co-morbidities, nutritive changes, and occurrence of adverse events during the 1-year treatment phase with the DJBL in the German DJBL registry. METHODS: Sixty-six patients from the registry were analyzed for efficacy, safety, and nutritional status. Patient data sets were analyzed at implantation, 3 and 6 months after implantation, and at explantation visits. RESULTS: Weight, body mass index, glycated hemoglobin, and low-density lipoprotein cholesterol primarily declined during the first 3 months after implantation, whereas systolic and diastolic blood pressure were predominantly reduced during the second half of the treatment phase. Severe DJBL-associated side effects were mainly documented at the explantation visit (intestinal obstruction [1.7%], dislocation [1.7%], and liver abscess [1.7%]). Measurements of serum concentrations of ferritin, albumin, vitamin B12, folic acid, 25-hydroxyvitamin D3 (25 OH-Vit-D3), and calcium provided suggestive evidence of a possible decrease of nutritional absorption of vitamins and trace elements by the DJBL. CONCLUSIONS: The DJBL demonstrates high efficacy with substantial improvement of all parameters of the metabolic syndrome and the potential for reduction of comedications in overweight patients with type 2 diabetes. These registry results are important to optimize recommendations for adaptation of concomitant medication, surveillance of adverse events, nutritional status and supplementation, and adaptation of the implantation period of the DJBL.

Specific Hepatic Sphingolipids Relate to Insulin Resistance, Oxidative Stress, and Inflammation in Nonalcoholic Steatohepatitis.

OBJECTIVE: Insulin resistance and nonalcoholic fatty liver disease have been linked to several lipid metabolites in animals, but their role in humans remains unclear. This study examined the relationship of sphingolipids with hepatic and peripheral metabolism in 21 insulin-resistant obese patients without (NAFL-) or with (NAFL+) nonalcoholic fatty liver and nonalcoholic steatohepatitis (NASH) and 7 healthy lean individuals undergoing tissue biopsies during bariatric or elective abdominal surgery. RESEARCH DESIGN AND METHODS: Hyperinsulinemic-euglycemic clamps with d-[6,6-2H2]glucose were performed to quantify tissue-specific insulin sensitivity. Hepatic oxidative capacity, lipid peroxidation, and the phosphorylated-to-total c-Jun N-terminal kinase (pJNK-to-tJNK) ratio were measured to assess mitochondrial function, oxidative stress, and inflammatory activity. RESULTS: Hepatic total ceramides were higher by 50% and 33% in NASH compared with NAFL+ and NAFL-, respectively. Only in NASH were hepatic dihydroceramides (16:0, 22:0, and 24:1) and lactosylceramides increased. Serum total ceramides and dihydroceramides (hepatic dihydroceramides 22:0 and 24:1) correlated negatively with whole-body but not with hepatic insulin sensitivity. Hepatic maximal respiration related positively to serum lactosylceramide subspecies, hepatic sphinganine, and lactosylceramide 14:0. Liver lipid peroxides (total ceramides, sphingomyelin 22:0) and the pJNK-to-tJNK ratio (ceramide 24:0; hexosylceramides 22:0, 24:0, and 24:1) all positively correlated with the respective hepatic sphingolipids. CONCLUSIONS: Sphingolipid species are not only increased in insulin-resistant humans with NASH but also correlate with hepatic oxidative stress and inflammation, suggesting that these lipids may play a role during progression of simple steatosis to NASH in humans.

Adaptation of hepatic mitochondrial function in humans with non-alcoholic fatty liver is lost in steatohepatitis.

The association of hepatic mitochondrial function with insulin resistance and non-alcoholic fatty liver (NAFL) or steatohepatitis (NASH) remains unclear. This study applied high-resolution respirometry to directly quantify mitochondrial respiration in liver biopsies of obese insulin-resistant humans without (n = 18) or with (n = 16) histologically proven NAFL or with NASH (n = 7) compared to lean individuals (n = 12). Despite similar mitochondrial content, obese humans with or without NAFL had 4.3- to 5.0-fold higher maximal respiration rates in isolated mitochondria than lean persons. NASH patients featured higher mitochondrial mass, but 31%-40% lower maximal respiration, which associated with greater hepatic insulin resistance, mitochondrial uncoupling, and leaking activity. In NASH, augmented hepatic oxidative stress (H2O2, lipid peroxides) and oxidative DNA damage (8-OH-deoxyguanosine) was paralleled by reduced anti-oxidant defense capacity and increased inflammatory response. These data suggest adaptation of the liver ("hepatic mitochondrial flexibility") at early stages of obesity-related insulin resistance, which is subsequently lost in NASH.

Status of bariatric surgery in Germany--results of the nationwide survey on bariatric surgery 2005-2007.

BACKGROUND: Most studies on bariatric surgery outcomes are performed as clinical trials or reflect the clinical experience in single centers. The status of bariatric surgery in Germany has been examined with the cooperation of clinics and hospitals at the Institute of Quality Assurance in Surgery at the Ottovon-Guericke University of Magdeburg (Germany) since January 1, 2005. METHODS: In this prospective multicenter observational study, the data obtained for all primary bariatric procedures, including all repeated operations, performed on consecutive patients with morbid obesity at participating hospitals from 2005 to 2007 were prospectively collected using an internet online data registry. Perioperative characteristics such as the spectrum of diagnostic measurements, type of surgical procedures, and short- and long-term outcomes were investigated. RESULTS: During the study period 3,123 surgical procedures were performed. In 2005 and 2006, gastric banding (GB) was the operation performed most frequently, followed by the Roux-en-Y gastric bypass (RYGBP). In 2007, a RYGBP was carried out in 42.1% of all bariatric procedures. Among all patients, 74.4% were female. The mean BMI ranged from 48.5 kg/m2 in 2005 to 48.0 kg/m2 in 2007. Follow-up data after 12 months were available for 63.8% of the patients operated in 2005 and 2006. The mortality was 0.1% (30 days) and 0.16% (overall). CONCLUSION: As indicated by the worldwide trend, there is an ongoing change from GB to sleeve gastrectomy (SG) and malabsorptive procedures. The BMI of German bariatric surgical patients is substantially higher than that of patients from most other countries. There were no differences in overall outcomes during follow-up as compared to published studies.