Anna Maria Wolf

Obesity-induced overexpression of miR-802 impairs glucose metabolism through silencing of Hnf1b

Insulin resistance represents a hallmark during the development of type 2 diabetes mellitus and in the pathogenesis of obesity-associated disturbances of glucose and lipid metabolism. MicroRNA (miRNA)-dependent post-transcriptional gene silencing has been recognized recently to control gene expression in disease development and progression, including that of insulin-resistant type 2 diabetes. The deregulation of miRNAs miR-143 (ref. 4), miR-181 (ref. 5), and miR-103 and miR-107 (ref. 6) alters hepatic insulin sensitivity. Here we report that the expression of miR-802 is increased in the liver of two obese mouse models and obese human subjects. Inducible transgenic overexpression of miR-802 in mice causes impaired glucose tolerance and attenuates insulin sensitivity, whereas reduction of miR-802 expression improves glucose tolerance and insulin action. We identify Hnf1b (also known as Tcf2) as a target of miR-802-dependent silencing, and show that short hairpin RNA (shRNA)-mediated reduction of Hnf1b in liver causes glucose intolerance, impairs insulin signalling and promotes hepatic gluconeogenesis. In turn, hepatic overexpression of Hnf1b improves insulin sensitivity in Leprdb/db mice. Thus, this study defines a critical role for deregulated expression of miR-802 in the development of obesity-associated impairment of glucose metabolism through targeting of Hnf1b, and assigns Hnf1b an unexpected role in the control of hepatic insulin sensitivity.

De novo lipogenesis in human fat and liver is linked to ChREBP-β and metabolic health

Clinical interest in de novo lipogenesis has been sparked by recent studies in rodents demonstrating that de novo lipogenesis specifically in white adipose tissue produces the insulin-sensitizing fatty acid palmitoleate. By contrast, hepatic lipogenesis is thought to contribute to metabolic disease. How de novo lipogenesis in white adipose tissue versus liver is altered in human obesity and insulin resistance is poorly understood. Here we show that lipogenic enzymes and the glucose transporter-4 are markedly decreased in white adipose tissue of insulin-resistant obese individuals compared with non-obese controls. By contrast, lipogenic enzymes are substantially upregulated in the liver of obese subjects. Bariatric weight loss restored de novo lipogenesis and glucose transporter-4 gene expression in white adipose tissue. Notably, lipogenic gene expression in both white adipose tissue and liver was strongly linked to the expression of carbohydrate-responsive element-binding protein-β and to metabolic risk markers. Thus, de novo lipogenesis predicts metabolic health in humans in a tissue-specific manner and is likely regulated by glucose-dependent carbohydrate-responsive element-binding protein activation.

Sepsis induced changes of adipokines and cytokines - septic patients compared to morbidly obese patients

BackgroundHyperglycemia and insulin resistance frequently occur in critically ill and in morbidly obese (MO) patients. Both conditions are associated with altered serum levels of cytokines and adipokines. In addition, obesity related alterations in adipokine expression contribute to insulin resistance in metabolic syndrome. In this study we examined the serum adipocytokine profile in critically ill patients, MO patients, and healthy blood donors.Methods33 patients who fulfilled the clinical criteria for severe sepsis or septic shock (SP) were prospectively enrolled in this study. A multiplex analysis was performed to evaluate plasma levels of adiponectin, resistin, leptin, active PAI-1, MCP-1, IL-1 alpha, IL-6, IL-8, IL-10, and TNF-alpha in 33 critically ill patients, 37 MO patients and 60 healthy blood donors (BD).ResultsIn SP, adiponectin was significantly lowered and resistin, active PAI-1, MCP-1, IL-1 alpha, IL-6, IL-8, IL-10, and TNF-alpha were significantly elevated compared to BD. Leptin levels were unchanged. In MO, adiponectin and IL-8 were significantly lowered, leptin, active PAI-1, MCP-1, IL-1 alpha, IL-6, and IL-10 significantly elevated, whereas resistin was unaltered.In SP, adiponectin correlated negatively with BMI, SAPS II and SOFA scores, while resistin correlated positively with SAPS II and SOFA scores and leptin correlated positively with the BMI. Adiponectin was approximately equally diminished in SP and MO compared to BD. With the exception of active PAI-1, cytokine levels in SP were clearly higher compared to MO.ConclusionA comparable adipocytokine profile was determined in critically ill and MO patients. As in MO, SP showed reduced adiponectin levels and elevated MCP-1, active PAI-1, IL-1 alpha, IL-6, and IL-10 levels. Leptin is only elevated in MO, while resistin, IL-8, and TNF-alpha is only elevated in SP. As in MO patients, increased levels of proinflammatory cytokines and altered levels of adipokines may contribute to the development of insulin resistance in critically ill patients.

Sepsis-Induced Adipokine Change with regard to Insulin Resistance.

Background. Assessment of white adipose tissue has changed in recent years, with WAT now being considered as an active endocrine organ, secreting a large number of bioactive mediators, so-called adipokines. Besides other functions, these adipokines are involved in inflammatory response thereby exhibiting predominantly proinflammatory or anti-inflammatory properties and contribute to insulin resistance. Methods. Comprehensive review of the literature of the role of adipokines relevant to critical care medicine using PubMed search. Results. Adiponectin—the prototype of an anti-inflammatory and insulin-sensitizing adipokine—is diminished in sepsis, while resistin—a protein with proinflammatory properties—is elevated. Plasminogen activator inhibitor-1, interleukin (IL)-1, IL-6, IL-8, and IL-10, and tumor-necrosis-factor-alpha mediate insulin resistance and are elevated in sepsis, while retinol-binding protein-4 concentrations are significantly reduced in sepsis. Chemerin displays potent anti-inflammatory and insulin-resistance properties, while monocyte chemotactic protein-1—increased in sepsis—contributes to macrophage infiltration in adipose tissue and insulin resistance. Conclusions. The expression of adipokines in humans is altered as well in obese as in septic patients with elevated levels of proinflammatory adipokines. Changes in adipokine levels in acute sepsis could contribute to insulin resistance. Consequently, in critically ill patients, these alterations underline a possible contribution of adipokines in the development of hyperglycemia.

Changed adipocytokine concentrations in colorectal tumor patients and morbidly obese patients compared to healthy controls

BackgroundObesity has been associated with increased incidence of colorectal cancer. Adipose tissue dysfunction accompanied with alterations in the release of adipocytokines has been proposed to contribute to cancer pathogenesis and progression. The aim of this study was to analyze plasma concentrations of several adipose tissue expressed hormones in colorectal cancer patients (CRC) and morbidly obese (MO) patients and to compare these concentrations to clinicopathological parameters.MethodsPlasma concentrations of adiponectin, resistin, leptin, active plasminogen activator inhibitor (PAI)-1, monocyte chemotactic protein (MCP)-1, interleukin (IL)-1 alpha, and tumor necrosis factor (TNF)-alpha were determined in 67 patients operated on for CRC (31 rectal cancers, 36 colon cancers), 37 patients operated on for morbid obesity and 60 healthy blood donors (BD).ResultsCompared to BD, leptin concentrations were lowered in CRC patients whereas those of MO patients were elevated. Adiponectin concentrations were only lowered in MO patients. Concentrations of MCP-1, PAI-1, and IL-1 alpha were elevated in both CRC and MO patients, while resistin and TNF-alpha were similarly expressed in MO and CRC patients compared to BD. Resistin concentrations positively correlated with tumor staging (p<0.002) and grading (p=0.015) of rectal tumor patients.ConclusionsThe results suggest that both MO and CRC have low-grade inflammation as part of their etiology.

Association of adiponectin levels and insulin demand in critically ill patients

Purpose: Intensive care unit patients usually have a deregulated glucose homeostasis and present with hyperglycemia and hyperinsulinemia, suggesting overall insulin resistance. Adiponectin has significant anti-inflammatory and insulin-sensitizing effects and is diminished in morbidly obese and in critically ill patients. Reduced adiponectin could contribute to insulin resistance in these patients. We examined how far insulin demand in critically ill patients is correlated with patient adiponectin levels. Patients and methods: Adiponectin, resistin, leptin, insulin demand, minimal and maximal blood sugar levels, epinephrine, and hydrocortisone demand were measured 1 day after diagnosis of severe sepsis or septic shock in 25 patients (8 female, 17 male; median age 65 years; range: 31 to 87 years). Results: Insulin demand (range: 0–8 IU/h; median 3.5 IU) was positively correlated with serum adiponectin levels (median: 10.1 μg/mL; range: 2.9–47.6 μg/mL; r = +0.56, P < 0.01). There was no significant correlation between insulin demand and leptin serum levels (median: 18.1 ng/mL; range: 0.3–80.7 ng/mL; r = +0.29, P = 0.08) or resistin serum levels (median: 103.9 ng/mL; range: 14.7–352.3 ng/mL; r = +0.13, P = 0.27). Epinephrine demand (median: 0.08 μg/kg*min; range: 0.02–0.63 μg/kg*min) was negatively correlated with male adiponectin levels (r = −0.58; P < 0.01; females: r = −0.36; P = 0.19) and positively correlated with resistin levels (r = 0.43; P = 0.02). Patient body mass index (median 26 kg/m2; range: 18–37) was positively correlated with serum leptin (r = 0.60; P < 0.01) but was not correlated with insulin demand (r = 0.19; P = 0.19), or adiponectin (females: r = −0.37, P = 0.18; males: r = −0.16, P = 0.27), or resistin levels (r = +0.17; P = 0.21). Conclusion: Adiponectin levels and insulin demand were positively correlated during sepsis. Adiponectin levels were negatively correlated with epinephrine demand in male patients and epinephrine demand was positively correlated with resistin levels, which might have increased insulin resistance. The relationship between adiponectin and insulin action in humans is more complex than often suggested.

Population Pharmacokinetics and Target Attainment of Meropenem in Plasma and Tissue of Morbidly Obese Patients after Laparoscopic Intraperitoneal Surgery.

ABSTRACT Meropenem serves as a clinically important, broad-spectrum antibiotic. While meropenem is commonly used in obese patients, its pharmacokinetics in this patient group is not well known. Our aim was to characterize the population pharmacokinetics and target attainment in plasma, subcutaneous tissue, and peritoneal fluid for meropenem in morbidly obese patients. Four doses of 1g meropenem were given as 15-min infusions every 8 h to five morbidly obese patients (body mass index [BMI], 47.6 to 62.3 kg/m2). After the fourth dose, serial meropenem concentrations were determined in plasma and, via microdialysis, in subcutaneous tissue and peritoneal fluid. All concentrations were analyzed simultaneously via population modeling, and target attainment probabilities predicted via Monte Carlo simulations using the target of unbound meropenem concentrations above the MIC for at least 40% of the dosing interval. For patients with 53 kg fat-free mass, total clearance was 18.7 liters/h and volume of distribution at steady state was 27.6 liters. The concentrations in subcutaneous tissue and peritoneal fluid largely paralleled those in plasma (equilibration half-life, <30 min). The area under the curve (AUC) in subcutaneous tissue divided by the plasma AUC had a mean of 0.721. For peritoneal fluid, this AUC ratio had a mean of 0.943. Target attainment probabilities were >90% after 1 g meropenem every 8 h as a 15-min infusion for MICs of up to 2 mg/liter in plasma and peritoneal fluid and 0.5 mg/liter in subcutaneous tissue. Meropenem pharmacokinetics in plasma and peritoneal fluid of obese patients was predictable, but subcutaneous tissue penetration varied greatly. (This study has been registered at ClinicalTrials.gov under registration no. NCT01407965.)

Panniculus, giant hernias and surgical problems in patients with morbid obesity.

Prevalence of morbid obesity is rising. Along with it, the adipose associated co-morbidities increase – included panniculus morbidus, the end stage of obesity of the abdominal wall. In the course of time panniculus often develop a herniation of bowel. An incarcerated hernia and acute exacerbation of a chronic inflammation of the panniculus must be treated immediately and presents a surgical challenge. The resection of such massive abdominal panniculus presents several technical problems to the surgeon. Preparation of long standing or fixed hernias may require demanding adhesiolysis. The wound created is huge and difficult to manage, and accompanied by considerable complications at the outset. We provide a comprehensive overview of a possible approach for panniculectomy and hernia repair and overlook of the existing literature.