Adipokines and insulin resistance

Advances in understanding the roles of leptin and adiponectin in the pathogenesis of chronic liver diseases

Leptin and adiponectin are adipokines that are abundantly expressed in adipose tissue and have multiple biological effects related to the development of human diseases. More and more studies have demonstrated that adipokines play important roles in the pathogenesis of steatosis, steatohepatitis and liver fibrosis, especially nonalcoholic fatty liver disease (NAFLD) and chronic hepatitis C (CHC). This paper reviews the recent advances in understanding the roles of leptin and adiponectin in the pathogenesis of liver diseases.

The emerging role of adipokines in osteoarthritis: a narrative review

Osteoarthritis (OA) is a most common multifactorial degenerative joint disease in elderly individuals. OA is affecting severely the quality of life of patients, while the causes of OA are not completely understood. Age, obesity, the female sex, and previous injury are considered as significant risk factors. Recently, increased levels of adipokines which are mainly produced by adipocytes have been detected in patients with osteoarthritis. Moreover, studies on different adipokines all reveal that they have played proinflammatory and catabolic/anabolic roles during the pathophysiology of OA. In the present review, we summarize current data on the effect of the adipose tissue-derived hormones leptin, adiponectin, resistin and visfatin on initiation and progression of OA.

Ghrelin in diabetes and metabolic syndrome

Metabolic syndrome is a cluster of related risk factors for cardiovascular disease, type 2 diabetes and liver disease. Obesity, which has become a global public health problem, is one of the major risk factors for development of metabolic syndrome and type 2 diabetes. Obesity is a complex disease, caused by the interplay between environmental and genetic factors. Ghrelin is one of the circulating peptides, which stimulates appetite and regulates energy balance, and thus is one of the candidate genes for obesity and T2DM. During the last years both basic research and genetic association studies have revealed association between the ghrelin gene and obesity, metabolic syndrome or type 2 diabetes.

Effects of chronic ethanol consumption on levels of adipokines in visceral adipose tissues and sera of rats

AIM

To investigate the effects of ethanol on adipokines (leptin, adiponectin, resistin, visfatin and cartonectin) levels in visceral adipose tissue (VAT) and sera, and explore the correlation between VAT and serum adipokine levels.

METHODS

Forty-eight Wistar rats were randomly divided into control, low, middle and high ethanol treatment groups that received 0, 0.5, 2.5, or 5.0 g of ethanol x kg(-1) x d(-1), respectively, via gastric tubes for 22 weeks. The levels of fasting blood glucose (FBG) and fasting serum insulin (FINS) were measured and homeostasis model assessment of insulin resistance (HOMA-IR) values were calculated. Adipokines in perirenal and epididymal VAT and sera were measured by enzyme-linked immunosorbent assays (ELISAs).

RESULTS

High-dose treatments of ethanol (vs control group) significantly increased FINS (eg 37.86%) and HOMA-IR values (eg 40.63%). In VAT, levels of leptin, resistin and visfatin in the middle- and high-dose groups were significantly elevated, whereas adiponectin and cartonectin levels decreased. In sera, changes in adipokine levels were similar to that observed in VAT, with the exception of cartonectin. These ethanol-induced effects were dose-dependent. A positive correlation existed between VAT and serum adipokine levels, except for cartonectin.

CONCLUSION

Chronic ethanol consumption affects adipokine levels in VAT and sera in a dose-dependent manner, with the exception of serum cartonectin. The altered levels of adipokines in VAT and sera are positively correlated.

Serum chemerin and vaspin in non-alcoholic fatty liver disease

OBJECTIVE

Chemerin and vaspin are new adipokines which may modulate inflammatory response and insulin sensitivity in non-alcoholic fatty liver disease (NAFLD). The aims of this study were to assess: (1) circulating levels of chemerin and vaspin and their association with liver histology and markers of liver injury in NAFLD patients; and (2) the relationship between the analyzed adipokines and insulin resistance.

MATERIAL AND METHODS

A total of 41 NAFLD patients with body mass index (BMI) 30.4 +/- 3.3 kg/m(2) [20 with non-alcoholic steatohepatitis (NASH) and BMI 30.3 +/- 3.3 kg/m(2) and 21 with simple steatosis/uncertain NASH (SS/UN) and BMI 30.5 +/- 3.4 kg/m(2)] and 10 healthy volunteers with BMI 24.0 +/- 2.9 kg/m(2) were included in the study.

RESULTS

Serum chemerin concentration was significantly higher in NAFLD patients compared to healthy volunteers (p = 0.009). Serum chemerin was significantly higher in patients with NASH compared to patients with SS/UN (p = 0.009). The homeostasis model assessment for insulin resistance (HOMA-IR) value was higher in patients with NASH than in patients with SS/UN (p = 0.01). Serum chemerin and HOMA-IR were positively associated with NAFLD activity score (r = 0.40, p = 0.02; and r = 0.43, p = 0.008, respectively). Serum chemerin was associated with hepatocyte ballooning degeneration (r = 0.37; p = 0.03), total cholesterol (r = 0.45; p = 0.008) and diastolic blood pressure (r = 0.41; p = 0.02). HOMA-IR was related to fibrosis stage (r = 0.51; p = 0.001) and inflammatory activity grade in portal tracts (r = 0.40; p = 0.01). Serum vaspin correlated with hepatocyte ballooning degeneration (r = 0.31; p = 0.04), alanine aminotransferase and aspartate aminotransferase (r = 0.33, p = 0.03; and r = 0.32, p = 0.04, respectively) and diastolic blood pressure (r = 0.39, p = 0.01).

CONCLUSIONS

This study shows for the first time that chemerin and vaspin serum concentrations are altered in patients with NAFLD. The analyzed adipokines appear to play a pivotal role in the pathogenesis of NAFLD, not only as regulators of insulin sensitivity, but also as mediators of the inflammatory process.

Inflammatory mediators of hepatic steatosis

Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming a world-wide public health problem. NAFLD represents a spectrum of disease ranging from "simple steatosis", which is considered relatively benign, to nonalcoholic steatohepatitis and to NAFLD-associated cirrhosis and end-stage liver disease. The etiology of NAFLD and its progression is complex and remains incompletely understood. The progression of the disease involves many factors. Apart from the two hits, the accumulation of TG and the development of fibrosis and necroinflammatory processes, exit numerous molecules associated with these two hits. Among them we can highlight the pro-inflammatory molecules and adiponectins. This review focuses on the growing evidence from both experimental and human studies suggesting a central role of cytokines in the pathogenesis of NAFLD. We review the role of cytokines as key regulators of insulin sensitivity and hepatic lipid overloading, liver injury and inflammation, and fibrosis with an emphasis on potential therapeutic implications.

Correlation of adiponectin receptor expression with cytokines and insulin sensitivity in growth hormone (GH)-treated children with Prader-Willi syndrome and in non-GH-treated obese children

CONTEXT

Prader-Willi syndrome (PWS), a genetic disorder characterized by obesity in early childhood, is reported to have elevated levels of adiponectin. The effects of adiponectin are mediated by adiponectin receptors (ADIPORs) that include ADIPOR1 and ADIPOR2. There is evidence that several cytokines, including adiponectin, TNF-alpha, and IL-6, are involved in insulin sensitivity.

OBJECTIVE AND METHODS

We measured the relative expression of adiponectin, ADIPORs, several proinflammatory cytokines including TNF-alpha, and IL-6 expression in peripheral blood mononuclear cells (PBMCs) of children with PWS and obese comparators using real-time PCR. Their correlation with homeostasis model assessment insulin resistance index (HOMA-IR) was analyzed.

PATIENTS

Thirty children with PWS (median age 7.1 yr, 18 males, 12 females) that were being treated with GH and 32 obese children not receiving GH treatment (median age 9.1 yr, 15 males, 17 females) for comparison were enrolled.

RESULTS

The PWS children had increased expression of ADIPOR2 (P = 0.02) and decreased expression of IL-6 (P = 0.03) compared with the comparison group. Moreover, there was a significant positive correlation between the ADIPORs and TNF-alpha (ADIPOR1 vs. TNF-alpha: r = 0.66, P < 0.001 in PWS, r = 0.80, P < 0.001 in comparison group; ADIPOR2 vs. TNF-alpha: r = 0.69, P < 0.001 in comparison group). The ADIPORs in the comparison group showed significant negative correlation with HOMA-IR (ADIPOR1 vs. HOMA-IR; rho = -0.41, P = 0.02, ADIPOR2 vs. HOMA-IR; rho = -0.46, P < 0.01).

CONCLUSION

The results of this study showed that inflammatory cytokine expression was closely associated with the expression of the ADIPORs in the PBMCs of both the children with PWS and the comparison group. Moreover, ADIPOR2 expression was highly expressed in the PBMCs of the children with PWS. A further study on the mechanism of increased expression of ADIPOR2 and its correlation with the expression of TNF-alpha in the PBMCs using the non-GH-treated PWS and obese control will be warranted because this study compared GH-treated PWS with an obese comparator group.

Serum galectin-3 is elevated in obesity and negatively correlates with glycosylated hemoglobin in type 2 diabetes

CONTEXT

Adipocytes synthesize galectin-3 whose deficiency protects from inflammation associated with metabolic diseases. We aimed to study circulating galectin-3 in obesity and type 2 diabetes (T2D).

STUDY DESIGN

Galectin-3 was measured by ELISA in the serum of male normal-weight and overweight controls and T2D patients and in T2D patients of both sexes. Because visceral fat contributes to systemic inflammation, galectin-3 was analyzed in paired samples of human and rodent sc and visceral adipose tissue. Visceral adipose tissue adipokines are released to the portal vein, and galectin-3 was analyzed in portal, hepatic, and systemic venous serum (PVS, HVS, and SVS, respectively) of patients with liver cirrhosis and in patients who underwent surgery for nonhepatic diseases. The effect of metformin on adipocyte galectin-3 was analyzed by immunoblot.

RESULTS

Circulating galectin-3 was similarly elevated in T2D and obesity compared with normal-weight individuals and revealed a body mass index-dependent positive correlation with leptin, resistin, IL-6, and age. In T2D patients, galectin-3 was increased in serum of patients with elevated C-reactive protein and negatively correlated with glycated hemoglobin. Metformin treatment was associated with lower systemic galectin-3. Reduced galectin-3 in metformin-incubated human adipocytes indicated that low galectin-3 may be a direct effect of this drug. Galectin-3 was higher in PVS compared with HVS and SVS, suggesting that the splanchnic region is a major site of galectin-3 synthesis. Low galectin-3 in HVS compared with PVS demonstrated hepatic removal.

CONCLUSIONS

Systemic galectin-3 is elevated in obesity and negatively correlates with glycated hemoglobin in T2D patients, pointing to a modifying function of galectin-3 in human metabolic diseases.

Beneficial effects of dietary restriction in type 2 diabetic rats: the role of adipokines on inflammation and insulin resistance

Inflammation plays an important role in diabetes mellitus and its complications. In this context, the negative cross-talk between adipose tissue and skeletal muscle leads to disturbances in muscle cell insulin signalling and induces insulin resistance. Because several studies have shown that energy restriction brings some benefits to diabetes, the aim of the present study was to evaluate the effects of dietary restriction on systemic and skeletal muscle inflammatory biomarkers, such C-reactive protein, adipokines and cytokines, and in insulin resistance in Goto-Kakizaki rats. This is an animal model of spontaneous non-obese type 2 diabetes with strongly insulin resistance and without dyslipidaemia. Animals were maintained during 2 months of dietary restriction (50 %) and were killed at 6 months of age. Some biochemical determinations were done using ELISA and Western blot. Data from the present study demonstrate that in Goto-Kakizaki rats the dietary restriction improved insulin resistance, NEFA levels and adipokine profile and ameliorated inflammatory cytokines in skeletal muscle. These results indicate that dietary restriction in type 2 diabetes enhances adipose tissue metabolism leading to an improved skeletal muscle insulin sensitivity.

Advances in understanding the role of leptin, adiponectin and resistin in liver fibrogenesis

Liver fibrosis is a wound healing reaction in response to a variety of chronic liver insults and is characterized by excessive extracellular matrix deposition within the liver. The term "adipocytokines]represents a group of polypeptide molecules produced primarily by adipose tissue. Accumulating evidence demonstrates that adipocytokines play a pivotal role in the pathogenesis of chronic liver diseases, such as nonalcoholic fatty liver disease. In this article, we will summarize the recent findings concerning the role of adipocytokines, such as leptin, adiponectin and resistin, in liver fibrogenesis.

Generation of pancreatic hormone-expressing islet-like cell aggregates from murine adipose tissue-derived stem cells

The success of cell replacement therapy for diabetes depends on the availability and generation of an adequate number of islets, preferably from an autologous origin. Stem cells are now being probed for the generation of physiologically competent, insulin-producing cells. In this investigation, we explored the potential of adipose tissue-derived stem cells (ASCs) to differentiate into pancreatic hormone-expressing islet-like cell aggregates (ICAs). We initiated ASC culture from epididymal fat pads of Swiss albino mice to obtain mesenchymal cells, murine epididymal (mE)-ASCs. Subsequent single-cell cloning resulted in a homogeneous cell population with a CD29(+)CD44(+)Sca-1(+) surface antigen expression profile. We formulated a 10-day differentiation protocol to generate insulin-expressing ICAs from mE-ASCs by progressively changing the differentiation cocktail on day 1, day 3, and day 5. Our stage-specific approach successfully differentiated mesodermic mE-ASCs into definitive endoderm (cells expressing Sox17, Foxa2, GATA-4, and cytokeratin [CK]-19), then into pancreatic endoderm (cells expressing pancreatic and duodenal homeobox [PDX]-1, Ngn3, NeuroD, Pax4, and glucose transporter 2), and finally into cells expressing pancreatic hormones (insulin, glucagon, somatostatin). Fluorescence-activated cell sorting analysis showed that day 5 ICAs contained 64.84% +/- 7.03% PDX-1(+) cells, and in day 10 mature ICAs, 48.17% +/- 3% of cells expressed C-peptide. Day 10 ICAs released C-peptide in a glucose-dependent manner, exhibiting in vitro functionality. Electron microscopy of day 10 ICAs revealed the presence of numerous secretory granules within the cell cytoplasm. Calcium alginate-encapsulated day 10 ICAs (1,000-1,200), when transplanted i.p. into streptozotocin-induced diabetic mice, restored normoglycemia within 2 weeks. The data presented here demonstrate the feasibility of using ASCs as a source of autologous stem cells to differentiate into the pancreatic lineage.

Diabetes and apoptosis: liver

The liver is a central regulator of glucose homeostasis and stores or releases glucose according to metabolic demands. In insulin resistant states or diabetes the dysregulation of hepatic glucose release contributes significantly to the pathophysiology of these conditions. Acute or chronic liver disease can aggravate insulin resistance and the physiological effects of insulin on hepatocytes are disturbed. Insulin resistance has also been recognized as an independent risk factor for the development of liver injury. In the healthy liver tissue homeostasis is achieved through cell turnover by apoptosis and dysregulation of the physiological process resulting in too much or too little cell death can have potentially devastating effects on liver tissue. The delineation of the signaling pathways that mediate apoptosis changed the paradigms of understanding of many liver diseases. These signaling events include cell surface based receptor-ligand systems and intracellular signaling pathways that are regulated through kinases on multiple levels. The dissection of these signaling pathways has shown that the regulators of apoptosis signaling events in hepatocytes can also modulate insulin signaling pathways and that mediators of insulin resistance in turn influence liver cell apoptosis. This review will summarize the potential crosstalk between apoptosis and insulin resistance signaling events and discuss the involved mediators.

Insulin resistance in hyperthyroidism: the role of IL6 and TNF alpha

OBJECTIVE

Although insulin resistance is a common finding in hyperthyroidism, the implicated mechanisms are obscure. The aim of this study was to investigate whether interleukin 6 (IL6) and tumour necrosis factor alpha (TNFalpha) are related to the development of insulin resistance in hyperthyroidism of nonautoimmune origin.

DESIGN AND METHODS

A meal was given to ten hyperthyroid (HR) and ten euthyroid (EU) women. Plasma samples were taken for 360 min from the radial artery for measurements of glucose, insulin, and nonesterified fatty acids (NEFA). IL6 and TNFalpha were measured preprandially from the superficial epigastric vein and from the radial artery.

RESULTS

i) In HR versus EU: (a) arterial glucose was similar (AUC(0-360) 2087+/-57 vs 2010+/-43 mM x min), but insulin was increased (AUC(0-360) 17 267+/-2447 vs 10 331+/-666 microU/ml x min, P=0.01), (b) homeostasis model assessment (HOMA) was increased (2.3+/-0.4 vs 1+/-0.1 kg/m(2), P=0.007), (c) arterial NEFA were increased (AUC(0-360) 136+/-18 vs 89+/-7 mmol/lxmin, P=0.03), (d) arterial IL6 (2+/-0.3 vs 0.9+/-0.1 pg/ml, P=0.0009) and TNFalpha (4.2+/-0.8 vs 1.5+/-0.2 pg/ml, P=0.003) were increased, and (e) IL6 production from the subcutaneous adipose tissue (AT) was increased (18+/-6 vs 5+/-1 pg/min per 100 ml tissue, P=0.04). ii) (a) Subcutaneous venous IL6 was positively associated with HOMA (beta-coefficient=1.7+/-0.7, P=0.049) and (b) although TNFalpha was not produced by the subcutaneous AT, arterial TNFalpha was positively associated with NEFA (AUC(0-360); beta-coefficient=0.045+/-0.01, P=0.005).

CONCLUSIONS

In hyperthyroidism: i) glucose and lipid metabolism are resistant to insulin, ii) subcutaneous AT releases IL6, which could then act as an endocrine mediator of insulin resistance, iii) although there is no net secretion of TNFalpha by the subcutaneous AT, increased systemic TNFalpha levels may be related to the development of insulin resistance in lipolysis.

The development and endocrine functions of adipose tissue

White adipose tissue is a mesenchymal tissue that begins developing in the fetus. Classically known for storing the body's fuel reserves, adipose tissue is now recognized as an endocrine organ. As such, the secretions from adipose tissue are known to affect several systems such as the vascular and immune systems and play major roles in metabolism. Numerous studies have shown nutrient or hormonal manipulations can greatly influence adipose tissue development. In addition, the associations between various disease states, such as insulin resistance and cardiovascular disease, and disregulation of adipose tissue seen in epidemiological and intervention studies are great. Evaluation of known adipokines suggests these factors secreted from adipose tissue play roles in several pathologies. As the identification of more adipokines and determination of their role in biological systems, and the interactions between adipocytes and other cells types continues, there is little doubt that we will gain a greater appreciation for a tissue once thought to simply store excess energy.

[Role of the endocrine system in the pathogenesis of non-alcoholic fatty liver disease]

The most frequent liver disorder in metabolic syndrome is the nonalcoholic fatty liver disease. Its pathogenesis is a complex, multifactorial process, characterized by insulin resistance and involvement of the endocrine system. Hypothyroidism may lead to nonalcoholic steatohepatitis via hyperlipidemia and obesity. Adult patients with growth hormone deficiency have a metabolic syndrome-like phenotype with obesity and many characteristic metabolic alterations. The chronic activation of the hypothalamic-pituitary-adrenal axis results in metabolic syndrome as well. Cushing's syndrome has also features of metabolic syndrome. Mild elevation of transaminase activities is commonly seen in patients with adrenal failure. Non-alcoholic steatosis is twice as common in postmenopusal as in premenopausal women and hormonal replacement therapy decreases the risk of steatosis. Insulin resistance, diabetes mellitus type 2, sleeping apnoe syndrome, cardiovascular disorders and non-alcoholic fatty liver disease are more frequent in polycystic ovary syndrome. Hypoandrogenism in males and hyperandrogenism in females may lead to fatty liver via obesity and insulin resistance. Adipokines (leptin, acylation stimulating protein, adiponectin) have a potential role in the pathogenesis of nonalcoholic fatty liver. The alterations of endocrine system must be considered in the background of cryptogenic liver diseases. The endocrine perspective may help the therapeutic approaches in the future.

Visfatin induces oxidative stress in differentiated C2C12 myotubes in an Akt- and MAPK-independent, NFkB-dependent manner

Adipose tissue is an important endocrine and metabolic tissue that is actively involved in cross-talk with peripheral organs such as skeletal muscle. It is likely that adipose-derived factors may underlie the development of insulin resistance in muscle. Thus, the cross-talk between adipose and muscle may be important for the propagation of obesity-related diseases. Visfatin (Pre-B-cell colony-enhancing factor 1 homolog/Nampt) is a recently discovered adipokine with pleiotropic functions. The aim of this study was to examine the effect of visfatin on cellular stress responses and signalling pathways in skeletal muscle. Visfatin treatment of differentiated C2C12 myotubes generated reactive oxygen species (ROS) comprising both superoxide and hydrogen peroxide that was dependent on de novo transcription and translation. In differentiated C2C12 myoblasts, visfatin had no effects on insulin-stimulated Akt phosphorylation nor on activation of the Akt signalling pathway. Additionally, visfatin-induced oxidative stress occurred independent of activation of the stress-activated protein kinases (MAPKs) ERK and p38. In contrast, phosphorylation of NFkB was associated with visfatin-mediated generation of ROS and blockade of this pathway via selective IKK inhibition led to a partial reduction in oxidative stress. Furthermore, the generation of ROS following visfatin treatment was highly dependent on both de novo transcription and translation. Taken together, these findings provide novel insights for the unique pathophysiological role of visfatin in skeletal muscle.

Rosiglitazone increases the expression of peroxisome proliferator-activated receptor-gamma target genes in adipose tissue, liver, and skeletal muscle in the sheep fetus in late gestation

Exposure to maternal overnutrition increases the expression of peroxisome proliferator-activated receptor-gamma (PPARgamma) in adipose tissue before birth, and it has been proposed that the precocial activation of PPARgamma target genes may lead to increased fat deposition in postnatal life. In this study, we determined the effect of intrafetal administration of a PPARgamma agonist, rosiglitazone, on PPARgamma target gene expression in fetal adipose tissue as well indirect actions of rosiglitazone on fetal liver and skeletal muscle. Osmotic pumps containing rosiglitazone (n = 7) or vehicle (15% ethanol, n = 7) were implanted into fetuses at 123-126 d gestation (term = 150 +/- 3 d gestation). At 137-141 d gestation, tissues were collected and mRNA expression of PPARgamma, lipoprotein lipase (LPL), adiponectin, and glycerol-3-phosphate dehydrogenase (G3PDH) in adipose tissue, PPARalpha and PPARgamma-coactivator 1alpha (PGC1alpha) in liver and muscle and phosphoenolpyruvate carboxykinase (PEPCK) in liver determined by quantitative real-time RT-PCR. Plasma insulin concentrations were lower in rosiglitazone-treated fetuses (P < 0.02). Rosiglitazone treatment resulted in increased expression of LPL and adiponectin mRNA (P < 0.01) in fetal adipose tissue. The expression of PPARalpha mRNA in liver (P < 0.05) and PGC1alpha mRNA (P < 0.02) in skeletal muscle were also increased by rosiglitazone treatment. Rosiglitazone treatment increased expression of PPARgamma target genes within fetal adipose tissue and also had direct or indirect actions on the fetal liver and muscle. The effects of activating PPARgamma in fetal adipose tissue mimic those induced by prenatal overnutrition, and it is therefore possible that activation of PPARgamma may be the initiating mechanism in the pathway from prenatal overnutrition to postnatal obesity.

Adipokines in liver diseases

Adipokines are polypeptides secreted in the adipose tissue in a regulated manner. While some of these molecules are expressed only by adipocytes, resident and infiltrating macrophages and components of the vascular stroma markedly contribute to expression of other adipokines. As a result, adipose tissue inflammation is associated with a modification in the pattern of adipokine secretion. Leptin, adiponectin, and resistin are the best-studied molecules in this class, but cytokines such as tumor necrosis factor or interleukin-6 are also secreted at high levels by the adipose tissue. Several other molecules have been recently identified and are actively investigated. Adipokines interfere with hepatic injury associated with fatty infiltration, differentially modulating steatosis, inflammation, and fibrosis. Several studies have investigated plasma levels of adiponectin in patients with nonalcoholic fatty liver disease, to establish correlations with the underlying state of insulin resistance and with the type and severity of hepatic damage. Hepatitis C is another disease where adipokines may represent a link between viral infection, steatosis, and metabolic disturbances. Identification of the mediators secreted by expanded adipose tissue and their pathogenic role is pivotal in consideration of the alarming increase in the prevalence of obesity and of the detrimental role that this condition exerts on the course of liver diseases.

Identification and treatment of metabolic complications in pediatric obesity

Metabolic consequences of obesity including insulin resistance, type 2 diabetes mellitus, hyperlipidemia, hypertension, polycystic ovarian syndrome, and non-alcoholic fatty liver infiltration are rapidly emerging in the pediatric population. Identifying effective strategies for identifying and treating these obesity related comorbidities in children are crucial to the prevention of future cardiovascular disease and poor health outcomes.This review discusses the pathophysiologic connections between obesity, metabolic disease and cardiovascular risk. Current evidence and recommendations for screening and treatment for the metabolic consequences of pediatric obesity are reviewed.

The peroxisome proliferator-activated receptor gamma agonist pioglitazone improves cardiometabolic risk and renal inflammation in murine lupus

Individuals with systemic lupus erythematosus (SLE) have a striking increase in the risk of premature atherosclerosis, a complication preceded by significant subclinical vascular damage. A proposed mechanism leading to accelerated vascular disease in SLE is an imbalance between vascular damage and repair, as patients with this disease display significant abnormalities in phenotype and function of endothelial progenitor cells. In addition, individuals with SLE have a higher incidence of insulin resistance which may further contribute to the increased cardiovascular risk. This study examined the role of the peroxisome proliferator activated receptor gamma agonist pioglitazone in improving endothelial function, endothelial progenitor cell numbers and functional capacity, metabolic parameters, and disease activity in the lupus-prone murine model New Zealand Black/New Zealand White (NZB x NZW)F(1). Ten-week-old prenephritic female NZB/NZW F(1) mice were exposed to 10 or 25 mg/kg/day of oral pioglitazone or vehicle for 15 or 24 wk. Mice exposed to pioglitazone exhibited pronounced enhancement in endothelial-dependent vasorelaxation of thoracic aortas and in endothelial progenitor cell function, as assessed by the capacity of bone marrow-derived endothelial progenitor cells to differentiate into mature endothelial cells. Pioglitazone-treated mice showed improvement in insulin resistance, adipokine, and lipid profile. Kidneys from pioglitazone-treated mice showed significant decreases in immune complex deposition, renal inflammation, T cell glomerular infiltration, and intrarenal synthesis of TNF-alpha, IL-1beta, and VCAM-1. These results indicate that peroxisome proliferator-activated receptor gamma agonists could serve as important tools in the prevention of premature cardiovascular disease and organ damage in SLE.

Adiponectin: a key adipokine in alcoholic fatty liver

Alcoholic fatty liver is a major risk factor for advanced liver injuries such as steatohepatitis, fibrosis, and cirrhosis. While the underlying mechanisms are multiple, the development of alcoholic fatty liver has been attributed to a combined increase in the rate of de novo lipogenesis and a decrease in the rate of fatty acid oxidation in animal liver. Among various transcriptional regulators, the hepatic SIRT1 (sirtuin 1)-AMPK (AMPK-activated kinase) signaling system represents a central target for the action of ethanol in the liver. Adiponectin is one of the adipocyte-derived adipokines with potent lipid-lowering properties. Growing evidence has demonstrated that the development of alcoholic fatty liver is associated with reduced circulating adiponectin levels, decreased hepatic adiponectin receptor expression, and impaired hepatic adiponectin signaling. Adiponectin confers protection against alcoholic fatty liver via modulation of complex hepatic signaling pathways largely controlled by the central regulatory system, SIRT1-AMPK axis. This review aims to integrate the current research findings of ethanol-mediated dysregulation of adiponectin and its receptors and to provide a comprehensive point of view for understanding the role of adiponectin signaling in the development of alcoholic fatty liver.

Influência da adiposidade sobre o risco inflamatório em pacientes com glicemia de jejum alterada

OBJETIVO: Investigar as alterações dos marcadores inflamatórios em obesos com glicemia de jejum alterada. MÉTODOS: Foram avaliados 125 indivíduos adultos tendo sido pesquisados: Índice de Massa Corporal, circunferência da cintura, glicemia de jejum, proteína C reativa ultra-sensível, ácido úrico e homocisteína. Os grupos apresentando glicemia de jejum normal (grupo 1) e glicemia de jejum alterada (grupo 2) foram comparados entre si e em associação aos subgrupos de obesos, sobrepesos e eutróficos. RESULTADOS: O grupo 2 apresentou maiores valores de circunferência da cintura (p<0,05), principalmente quando associados ao excesso de peso. Adicionalmente, o grupo 2 mostrou valores de proteína C reativa e ácido úrico superiores, sendo os dos obesos maiores que os com sobrepeso e os eutróficos, enquanto a homocisteína foi semelhante entre obesos, com sobrepeso e eutróficos. O Índice de Massa Corporal correlacionou-se positivamente com ambos ácido úrico (r=0,39, p<0,01) e proteína C reativa (r=0,37; p<0,01). A circunferência da cintura apresentou correlação apenas com o ácido úrico (r=0,53, p<0,01). Porém, a correlação entre Índice de Massa Corporal e proteína C reativa foi significante no grupo 2 (r=0,66, p<0,01), mas não no grupo 1 (r=0,25, p>0,05). O mesmo resultado foi encontrado em relação à circunferência da cintura e à proteína C reativa, que se correlacionaram significantemente somente na presença de glicemia de jejum alterada (r=0,40, p<0,05). Na regressão logística, a circunferência da cintura foi a variável explicativa (11%, p<0,01) da alteração da glicemia de jejum. CONCLUSÃO: Os estados pró-oxidativo e pró-inflamatório estiveram significantemente associados à glicemia de jejum alterada na presença de adiposidade corporal.