Resistin increases with obesity and atherosclerotic risk factors in patients with myocardial infarction

Regulation of cardiovascular health and disease by visceral adipose tissue-derived metabolic hormones

Visceral adipose tissue (VAT) is a metabolic organ known to regulate fat mass, and glucose and nutrient homeostasis. VAT is an active endocrine gland that synthesizes and secretes numerous bioactive mediators called 'adipocytokines/adipokines' into systemic circulation. These adipocytokines act on organs of metabolic importance like the liver and skeletal muscle. Multiple preclinical and in vitro studies showed strong evidence of the roles of adipocytokines in the regulation of metabolic disorders like diabetes, obesity and insulin resistance. Adipocytokines, such as adiponectin and omentin, are anti-inflammatory and have been shown to prevent atherogenesis by increasing nitric oxide (NO) production by the endothelium, suppressing endothelium-derived inflammation and decreasing foam cell formation. By inhibiting differentiation of vascular smooth muscle cells (VSMC) into osteoblasts, adiponectin and omentin prevent vascular calcification. On the other hand, adipocytokines like leptin and resistin induce inflammation and endothelial dysfunction that leads to vasoconstriction. By promoting VSMC migration and proliferation, extracellular matrix degradation and inflammatory polarization of macrophages, leptin and resistin increase the risk of atherosclerotic plaque vulnerability and rupture. Additionally, the plasma concentrations of these adipocytokines alter in ageing, rendering older humans vulnerable to cardiovascular disease. The disturbances in the normal physiological concentrations of these adipocytokines secreted by VAT under pathological conditions impede the normal functions of various organs and affect cardiovascular health. These adipokines could be used for both diagnostic and therapeutic purposes in cardiovascular disease.

The possible role of endocrine dysfunction of adipose tissue in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is diabetes that is first diagnosed in the second or third trimester of pregnancy in patients who did not have a history of diabetes before pregnancy. Consequences of GDM include increased risk of macrosomia and birth complications in the infant and an increased risk of maternal type 2 diabetes mellitus (T2DM) after pregnancy. There is also a longer-term risk of obesity, T2DM, and cardiovascular diseases in the child. GDM is the result of impaired glucose tolerance due to pancreatic β-cell dysfunction on a background of insulin resistance that physiologically increases during pregnancy. The strongest clinical predictors of GDM are overweight and obesity. The fact that women with GDM are more likely to be overweight or obese suggests that adipose tissue dysfunction may be involved in the pathogenesis of GDM, similarly to T2DM. Adipose tissue is not only involved in energy storage but also functions as an active endocrine organ secreting adipokines (specific hormones and cytokines) with the ability to alter insulin sensitivity. Recent evidence points to a crucial role of numerous adipokines produced by fat in the development of GDM. The following text summarizes the current knowledge about a possible role of selected adipokines in the development of GDM.

HIMF deletion ameliorates acute myocardial ischemic injury by promoting macrophage transformation to reparative subtype

Appropriately manipulating macrophage M1/M2 phenotypic transition is a promising therapeutic strategy for tissue repair after myocardial infarction (MI). Here we showed that gene ablation of hypoxia-induced mitogenic factor (HIMF) in mice (Himf^−/− and HIMF^flox/flox;Lyz2-Cre) attenuated M1 macrophage-dominated inflammatory response and promoted M2 macrophage accumulation in infarcted hearts. This in turn reduced myocardial infarct size and improved cardiac function after MI. Correspondingly, expression of HIMF in macrophages induced expression of pro-inflammatory cytokines; the culturing medium of HIMF-overexpressing macrophages impaired the cardiac fibroblast viability and function. Furthermore, macrophage HIMF was found to up-regulate C/EBP-homologous protein (CHOP) expression, which exaggerated the release of pro-inflammatory cytokines via activating signal transducer of activator of transcription 1 (STAT1) and 3 (STAT3) signaling. Together these data suggested that HIMF promotes M1-type and prohibits M2-type macrophage polarization by activating the CHOP–STAT1/STAT3 signaling pathway to negatively regulate myocardial repair. HIMF might thus constitute a novel target to treat MI.

Resistin/Uric Acid Index as a Prognostic Factor in Adolescents with Obesity after Lifestyle Intervention

OBJECTIVE

To evaluate the resistin/uric acid index as a prognostic factor associated with body mass index (BMI) z-score change after 1 year of lifestyle interventions for obesity.

STUDY DESIGN

In this prospective cohort study, we included 102 adolescents with overweight or obesity (BMI ≥85th percentile). Weight and height were measured at the start of the lifestyle change intervention and 12 months later. Serum levels of resistin and uric acid were quantified at the beginning of the intervention. The intervention consisted of nutrition education, exercise, and physical activity promotion.

RESULTS

The sample included 54 girls and 48 boys; the median age was 11 years (range 10-16 years). The BMI z-score decreased during follow-up (median BMI z-score at baseline was 1.81 vs 1.70 after 1 year, P < .001). The resistin/uric acid index was positively correlated with BMI z-score change (r = 0.27, P < .01). In the linear regression analysis, the resistin/uric acid index was significantly associated with BMI z-score modification at the 12-month follow-up (β = 0.17; 95% CI 0.08-0.26; P < .01).

CONCLUSIONS

The resistin/uric acid index can be considered a prognostic factor for identifying adolescents with overweight or obesity with a greater probability of improving their BMI. This index could help establish different interventions for adolescents with overweight and obesity; however, additional studies are needed to confirm the usefulness of this index.

Variation of Resistin Gene Is Correlated with Insulin Resistance in Obese People of Indonesia

BACKGROUND

Obesity is considered associated with an increase of resistin levels that plays a role in the regulation of energy and maintaining fasting blood glucose. Polymorphism of resistin is thought to be correlated with the levels of resistin and insulin resistance.

AIM

This study aimed to examine the association of +299G > A and -420C > G resistin (RETN) gene with resistin level and insulin resistance in obese people of Indonesia.

METHODS

We examined 142 healthy unrelated subjects consisting of 71 obese and 71 controls. Fasting blood glucose was measured by the enzymatic method while the resistin and insulin levels were measured by Elisa method. Insulin resistance was calculated by HOMA-IR index. Polymorphisms of RETN genes were examined by the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method, and the data was tested. The data were correlated with Kruskal Wallis continue logistic regression and simple linear regression.

RESULTS

In the obese group, there was an increased level of insulin (17.74 vs 11.27 mU/L) and insulin resistance (HOMA-IR 3.9 vs 1.46) compared to the control group. Polymorphism of +299G > A was associated with insulin resistance (GA and GA + AA genotype significantly different compare GG genotype with P < 0.001). Resistin level was negatively correlated with insulin level (P = 0.017).

CONCLUSION

In this study, polymorphism of +299G > A was identified as a risk factor for insulin resistance, and there was a significant association of serum resistin level with insulin level in the population of Indonesia.

Endothelial permeability, LDL deposition, and cardiovascular risk factors-a review

Early atherosclerosis features functional and structural changes in the endothelial barrier function that affect the traffic of molecules and solutes between the vessel lumen and the vascular wall. Such changes are mechanistically related to the development of atherosclerosis. Proatherogenic stimuli and cardiovascular risk factors, such as dyslipidaemias, diabetes, obesity, and smoking, all increase endothelial permeability sharing a common signalling denominator: an imbalance in the production/disposal of reactive oxygen species (ROS), broadly termed oxidative stress. Mostly as a consequence of the activation of enzymatic systems leading to ROS overproduction, proatherogenic factors lead to a pro-inflammatory status that translates in changes in gene expression and functional rearrangements, including changes in the transendothelial transport of molecules, leading to the deposition of low-density lipoproteins (LDL) and the subsequent infiltration of circulating leucocytes in the intima. In this review, we focus on such early changes in atherogenesis and on the concept that proatherogenic stimuli and risk factors for cardiovascular disease, by altering the endothelial barrier properties, co-ordinately trigger the accumulation of LDL in the intima and ultimately plaque formation.

Resistin is a prognostic factor for death in type 2 diabetes

PURPOSE

To investigate the association of leptin, resistin, and tumour necrosis factor α (TNF-α) with prognosis in type 2 diabetes (T2D).

METHODS

Analysis included 284 T2D patients. Apart from routine laboratory parameters, baseline leptin, resistin, and TNF-α concentrations were measured. Patients were followed for a median of 5.4 years. The primary endpoint was all-cause death at follow-up. The secondary endpoint was a composite of death, acute coronary syndrome, and stroke or transient ischemic attack.

RESULTS

At baseline, median age was 68 years, and 48% of patients were female. Data on the primary endpoint were obtained for all patients: 32 (11%) died during follow-up. Data on the secondary endpoint were available for 230 patients, of whom 45 (20%) reached the secondary endpoint. In univariate analyses, older age, heart failure, lower-glomerular filtration rate, and higher resistin, TNF-α and NT-proBNP concentrations were predictors of the study endpoints. Of these variables, only resistin remained an independent predictor of both study endpoints in multivariate models. In receiver-operating characteristic analysis, area under the curve for resistin was 0.7. Resistin concentration of greater than or equal to 11.4 ng/mL had sensitivity of 41% and specificity of 91% for prediction of death at follow-up (Youden's index).

CONCLUSIONS

Higher resistin is associated with reduced survival in T2D, irrespectively of TNF-α. Resistin concentration of above 11 ng/mL indicates T2D patients at an increased risk of unfavourable outcomes. Leptin was not a prognostic factor. These results suggest that in T2D, association of resistin with unfavourable outcomes might, at least in part, result from its pro-inflammatory properties.

Association between serum resistin, adiposity measures and inflammatory makers in women without cardiovascular diseases

AIMS

The convergence of obesity and inflammation in the pathogenesis of cardiovascular diseases (CVD) has been recognized over the past decade. Resistin has emerged as a novel secreted protein with links to both insulin resistance and inflammation. We aimed to investigate the relationship between changes in serum resistin levels with metabolic parameters, including obesity and inflammatory markers in women free of CVD.

METHODS AND RESULTS

A total of 200 apparently healthy women were consecutively recruited from the Out-patients Clinics at King Abdulaziz university Hospital in Jeddah, Saudi Arabia. They were classified into 4 groups based on quartile for serum resistin. Anthropometric variables were measured in all study subjects. Fasting blood samples were collected for measurement of lipid profile, blood glucose and inflammatory markers. Study subjects within the upper quartile (Q4) had significantly higher body height (p < 0.0001), waist and hip circumferences (p < 0.05) and inflammatory markers (p < 0.0001) values than those in the lower quartile (Q1). Significant correlations were found between circulating resistin levels and systolic blood pressure, some anthropometric measures as well as inflammatory markers.

CONCLUSION

Serum resistin levels were found to be increased in overweight and obese women. Resistin was also independently associated with hs-CRP in women free of CVD, suggesting that resistin may be related to low-grade inflammation among obese subjects in the absence of overt CVD.

The role of obesity and adipose tissue dysfunction in gestational diabetes mellitus

Gestational diabetes mellitus is defined as diabetes diagnosed in the second or third trimester of pregnancy in patients with no history of diabetes prior to gestation. It is the most common complication of pregnancy. The underlying pathophysiology shares some common features with type 2 diabetes mellitus (T2DM) combining relatively insufficient insulin secretion with increased peripheral insulin resistance. While a certain degree of insulin resistance is the physiological characteristics of the second half of pregnancy, it is significantly more pronounced in patients with gestational diabetes. Adipose tissue dysfunction and subclinical inflammation in obesity are well-described causes of increased insulin resistance in non-pregnant subjects and are often observed in individuals with T2DM. Emerging evidence of altered adipokine expression and local inflammation in adipose tissue in patients with gestational diabetes suggests an important involvement of adipose tissue in its etiopathogenesis. This review aims to summarize current knowledge of adipose tissue dysfunction and its role in the development of gestational diabetes. We specifically focus on the significance of alterations of adipokines and immunocompetent cells number and phenotype in fat. Detailed understanding of the role of adipose tissue in gestational diabetes may provide new insights into its pathophysiology and open new possibilities of its prevention and treatment.

Treatment of Type-1 Hepatorenal Syndrome with Pentoxifylline: A Randomized Placebo Controlled Clinical Trial

INTRODUCTION

Type-1 hepatorenal syndrome (HRS-1) portends a poor prognosis in patients with cirrhosis. Currently available medical therapies are largely ineffective, save for liver transplantation. We aimed to determine if pentoxifylline (PTX) therapy in addition to the standard of care of volume expansion with albumin and vasoconstriction with midodrine and octreotide (AMO) is safe and efficacious compared to AMO in HRS-1 treatment.

MATERIAL AND METHODS

Hospitalized subjects with decompensated cirrhosis and HRS-1 were enrolled. PTX or placebo was administered with AMO therapy for up to 14 days. The primary endpoint was HRS-1 resolution (serum creatinine ≤ 1.5 g/dL for &gt; 24 h). Secondary endpoints were change in creatinine and MELD score, partial treatment response, 30-and 180-day overall and transplant free survival.

RESULTS

Twelve subjects with mean age 58.9 ± 6.2 years were enrolled and randomized. Mean MELD score was 26.5 ± 7.4 and 58.3% were male. Overall cohort 30- and 180-day survival was 58.3% and 33.3% respectively. Two subjects underwent liver transplantation. HRS-1 resolution (16.7% vs. 16.7%, p = 1.000), partial treatment response (33.3% vs. 16.7%, p = 0.505), change in creatinine (+0.48 g/dL, 95% CI -0.49-1.46 vs. +0.03 g/dL, 95% CI -0.64- 0.70, p = 0.427), 30-day survival (66.6% vs. 50.0%, p = 0.558) and 180-day survival (50.0% vs. 16.7%, p = 0.221) were similar between the two groups. Serious adverse events necessitating treatment discontinuation were rare (n = 1, PTX).

DISCUSSION

The addition of PTX to AMO in the treatment of HRS-1 is safe when compared to the current standard of care. Future large-scale prospective study to validate the efficacy of this treatment seems warranted.

Lymphocytes and macrophages in adipose tissue in obesity: markers or makers of subclinical inflammation?

Obesity is accompanied by the development of chronic low-grade inflammation in adipose tissue. The presence of chronic inflammatory response along with metabolically harmful factors released by adipose tissue into the circulation is associated with several metabolic complications of obesity such as type 2 diabetes mellitus or accelerated atherosclerosis. The present review is focused on macrophages and lymphocytes and their possible role in low-grade inflammation in fat. Both macrophages and lymphocytes respond to obesity-induced adipocyte hypertrophy by their migration into adipose tissue. After activation and differentiation, they contribute to the development of local inflammatory response and modulation of endocrine function of adipose tissue. Despite intensive research, the exact role of lymphocytes and macrophages within adipose tissue is only partially clarified and various data obtained by different approaches bring ambiguous information with respect to their polarization and cytokine production. Compared to immunocompetent cells, the role of adipocytes in the obesity-related adipose tissue inflammation is often underestimated despite their abundant production of factors with immunomodulatory actions such as cytokines or adipokines such as leptin, adiponektin, and others. In summary, conflicting evidence together with only partial correlation of in vitro findings with true in vivo situation due to great heterogeneity and molecular complexity of tissue environment calls for intensive research in this rapidly evolving and important area.

Leptin decreases the expression of low-density lipoprotein receptor via PCSK9 pathway: linking dyslipidemia with obesity

Background

Previous studies have suggested that people with obesity showed elevated serum levels of leptin as well as lipid dysfunction and proprotein convertase subtilisin/kexin type 9 (PCSK9) played an important role in the regulation of lipid metabolism recently. The aim of this study was to determine if leptin participated in regulating the uptake of low-density lipoproteins (LDL) in hepatocytes via PCSK9.

Methods

HepG2 cells were treated with human recombinant leptin. The impact of leptin on cellular low density lipoprotein receptor (LDLR) and PCSK9 protein levels was determined by Western blot. Dil-LDL uptake assay was performed to examine the LDLR function. Specific small interfering RNAs (siRNAs) were used to interfere the expressions of target proteins.

Results

The expression of LDLR and LDL uptake could be significantly down-regulated by leptin treatment while the expressions of PCSK9 and hepatocyte nuclear factor 1α (HNF1α) were enhanced in HepG2 cells. Furthermore, inhibition of PCSK9 or HNF1α expression by siRNAs rescued the reduction of LDLR expression and LDL uptake by leptin. We found that leptin activated the p38 mitogen-activated protein kinase (p38MAPK) signaling pathway. Moreover, the changes of the expressions of HNF1α, PCSK9, LDLR, and LDL uptake induced by leptin could be blocked by p38MAPK inhibitor (SB203580). Additionally, leptin attenuated the up-regulation of LDLR caused by atorvastatin in HepG2 cells.

Conclusions

These findings indicated firstly that leptin reduced LDLR levels in hepatocyte via PCSK9 pathway, suggesting that PCSK9 might be a alternative target for dyslipidemia in the obesity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1032-4) contains supplementary material, which is available to authorized users.

Obesity, Serum Resistin and Leptin Levels Linked to Coronary Artery Disease

Background

Clinical studies have demonstrated that adipocytokines play an important role in developing atherosclerotic cardiovascular diseases.

Objective

The aim of study was to evaluate the relationship between serum resistin and leptin levels with obesity and coronary artery disease (CAD).

Methods

In a cross-sectional study, we assessed the levels of serum resistin and leptin, C-reactive protein (CRP), lipid profile and cardiac enzyme tests (AST, CPK, LDH, CK-MB) in 40 CAD patients compared to 40 healthy controls. Anthropometric measurements including weight and height for calculating of body mass index (BMI), and waist circumference (WC) were performed for evaluation of obesity.

Results

CAD patients had increased levels of leptin and CRP, (p < 0.001), cholesterol (p < 0.05), triglyceride (p < 0.01), and WC (p < 0.05) compared to healthy controls. There was no statistical difference between CAD and control subjects for resistin (p = 0.058). In a multiple regression analysis, only an association between serum leptin with BMI (β = 0.480, p < 0.05) and WC (β = 1.386, p < 0.05) was found.

Conclusions

The findings suggest that leptin is a better marker of fat mass value than resistin and may be considered an independent risk factor for cardiac disorders that is largely dependent on obesity. However, further prospective studies are needed to confirm these results.

PKCε mediates resistin-induced NADPH oxidase activation and inflammation leading to smooth muscle cell dysfunction and intimal hyperplasia

BACKGROUND AND AIMS

Resistin has been implicated in cardiovascular disease and poor interventional cardiovascular outcomes. Previous studies by our group demonstrated resistin promoted vascular smooth muscle cell (VSMC) migration through protein kinase C epsilon (PKCε) pathways, while few others showed that resistin induced reactive oxygen species (ROS) generation in various cell types. In this study, we aim to systemically examine the functional role of resistin at the cellular and tissue levels as well as the potential mechanistic relationship between resistin-induced PKCε activation and ROS production.

METHODS

Plasma collected from patients undergoing carotid interventions was analyzed for resistin level and ROS. VSMCs were treated with resistin in the presence or absence of PKCε and NADPH oxidase (Nox)-specific inhibitors. Intracellular ROS production was analyzed using confocal microscopy and Nox activity with chemiluminescence. In vivo studies were performed in apolipoprotein E knock out (ApoE^-/-) mice to determine therapeutic effects of PKCε-specific inhibitor, using the guide-wire injury model.

RESULTS

We observed significant correlation between plasma resistin and circulating levels of oxidative stress in patients with severe atherosclerotic disease. We also demonstrated that resistin induced ROS production via PKCε-mediated Nox activation. Resistin-induced ROS production was time-dependent, and Nox4 was the primary isoform involved. Inhibition of Nox completely abolished resistin-exaggerated VSMC proliferation, migration and dedifferentiation, as well as pro-inflammatory cytokine release. Upstream modulation of PKCε significantly reduced resistin-mediated cytosolic ROS, Nox activity and VSMC dysfunction. Moreover, PKCε-specific inhibitor mitigated resistin-induced Nox activation and intimal hyperplasia in ApoE^-/- mice.

CONCLUSIONS

Resistin-associated VSMC dysfunction and intimal hyperplasia are related to PKCε-dependent Nox activation and ROS generation. Targeting the PKCε-Nox pathway may represent a novel strategy in managing resistin-associated atherosclerotic complications.

Concentrations of adipokines in children before and after hematopoietic stem cell transplantation

Adipokines have multiple effects, including regulation of glucose metabolism, cell proliferation, inflammation, and angiogenesis. The aim of the study was to determine plasma concentrations of adiponectin, apelin, leptin, and resistin as well as soluble leptin receptor in pediatric hematopoietic stem cell transplantation (HSCT). The expression of genes encoding the studied peptides was measured using microarray technique. Plasma concentrations of tested peptides were measured before and after oral glucose tolerance test in children treated with HSCT (n = 38) and in healthy controls (n = 26). The peptides were measured before HSCT (pre-HSCT group; n = 38) and after a median of 6 months after HSCT (post-HSCT group; n = 27 of 38 children treated with HSCT). In addition, measurements of fasting plasma glucose, insulin, lipids, and high-sensitivity C-reactive protein (hsCRP) were performed. In both HSCT groups, atherogenic lipid profile, low-grade systemic inflammation was observed. Leptin, adiponectin, and resistin also appear to be good markers of disease burden and low-grade systemic inflammation. Adipokines may be good markers of disease burden and may influence metabolic complications of HSCT. Future studies on larger groups of patients will explain if changes of the concentrations of leptin, adiponectin, and apelin observed in our study and confirmed by expression levels influence engraftment and reconstitution of cell lines.

Resistin, an Adipokine with Non-Generalized Actions on Sympathetic Nerve Activity

The World Health Organization has called obesity a global epidemic. There is a strong association between body weight gain and blood pressure. A major determinant of blood pressure is the level of activity in sympathetic nerves innervating cardiovascular organs. A characteristic of obesity, in both humans and in animal models, is an increase in sympathetic nerve activity to the skeletal muscle vasculature and to the kidneys. Obesity is now recognized as a chronic, low level inflammatory condition, and pro-inflammatory cytokines are elevated including those produced by adipose tissue. The most well-known adipokine released from fat tissue is leptin. The adipokine, resistin, is also released from adipose tissue. Resistin can act in the central nervous system to influence the sympathetic nerve activity. Here, we review the effects of resistin on sympathetic nerve activity and compare them with leptin. We build an argument that resistin and leptin may have complex interactions. Firstly, they may augment each other as both are excitatory on sympathetic nerves innervating cardiovascular organs; In contrast, they could antagonize each other's actions on brown adipose tissue, a key metabolic organ. These interactions may be important in conditions in which leptin and resistin are elevated, such as in obesity.

Adipose Tissue as an Endocrine Organ: An Update on Pro-inflammatory and Anti-inflammatory Microenvironment

Adipose tissue is recognized as an active endocrine organ that produces a number of endocrine substances referred to as "adipokines" including leptin, adiponectin, adipolin, visfatin, omentin, tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), resistin, pigment epithelium-derived factor (PEDF), and progranulin (PGRN) which play an important role in the food intake regulation and significantly influence insulin sensitivity and in some cases directly affect insulin resistance in skeletal muscle, liver, and adipose tissue. The review summarizes current knowledge about adipose tissue-derived hormones and their influence on energy homeostasis regulation. The possible therapeutic potential of these adipokines in the treatment of insulin resistance, endothelial dysfunction, a pro-inflammatory response, obesity, eating disorders, progression of atherosclerosis, type 1 diabetes, and type 2 diabetes is discussed.

Gingival crevicular fluid and serum levels of resistin in obese and non-obese subjects with and without periodontitis and association with single nucleotide polymorphism at -420

OBJECTIVE

Resistin is an adipocytokine, which have been studied for its role in insulin resistance and recently in inflammation. The present study was designed to study the gingival crevicular fluid (GCF) and serum levels of resistin in obese and non-obese subjects with and without periodontitis and to further study the association of single-nucleotide polymorphism (SNP) -420 with these levels.

MATERIALS AND METHODS

A total of 90 subjects were divided based on gingival index (GI), probing pocket depth (PPD), clinical attachment level (CAL), body mass index (BMI) and waist circumference (WC) into: Non-obese healthy (Group 1, n = 30, BMI ≤ 22.9 and WC < 90 for male subjects and < 80 for female subjects, PPD ≤ 3 mm, CAL = 0, GI = 0), non-obese periodontitis (Group 2, n = 30, BMI ≤ 22.9 and WC < 90 for male subjects and < 80 for female subjects, PPD ≥ 5 mm, CAL ≥ 3, GI ≥ 1) and obese periodontitis (Group 3, n = 30, BMI ≥ 25.0 and WC ≥ 90 for male subjects and ≥ 80 for female subjects, PPD ≥ 5 mm, CAL ≥ 3, GI ≥ 1). The GCF and serum levels of resistin were quantified using enzyme-linked immunosorbent assay and compared amongst the study groups. Further, the association of the resistin levels with periodontal inflammation and SNP at -420 was studied.

RESULTS

The mean resistin levels were highest in Group 3 (14.66 ± 5.93 ng/ml and 9.99 ± 7.22 μg/ml), followed by Group 2 (12.34 ± 4.31 ng/ml and 7.47 ± 3.94 μg/ml) and least in Group 1 (7.09 ± 3.34 ng/ml and 6.05 ± 3.61 μg/ml) in serum and GCF respectively. The levels positively correlated with GI, PPD, CAL, BMI, WC and waist-hip ratio (r < 0.6). The SNP at -420 showed that GG genotype was associated with Group 2 and 3 i.e. periodontitis, while CC genotype was associated with periodontal health. The GG genotype was also associated with high serum resistin levels as compared to CC and CG genotypes.

CONCLUSION

Resistin levels increased with periodontal inflammation indicating its possible inflammatory role in periodontitis. GG genotype at -420 is associated with increased serum resistin and with periodontal disease. Thus, further research is needed to study GG genotype and increased serum and GCF resistin levels as putative risk factors for periodontal diseases.

Polymorphisms in RETN gene and susceptibility to colon cancer in Saudi patients

BACKGROUND AND OBJECTIVES

Resistin is an adipocytokine, which has been studied for its role in insulin resistance and recently in inflammation. Several single-nucleotide polymorphisms (SNPs) have been identified in the human resistin gene (RETN). This study aims to investigate the association of RETN rs1862513 (C-420G) and rs3745367 (G+299A) SNPs with the colon cancer risk in Saudi patients.

DESIGN AND SETTING

This is a case-control study conducted among Saudi adult colon cancer patients recruited from King Abdulaziz Hospital and Oncology Center in Jeddah, Saudi Arabia.

SUBJECTS AND METHODS

In this study, 120 Saudi volunteers (60 colon cancer patients and 60 disease-free controls) were studied. The SNPs were determined by polymerase chain reaction (PCR) and genotyping using PCR- restriction fragment length polymorphism analysis.

RESULTS

In comparing the result obtained for the patient group with that of the controls, colon cancer group displayed different genotype distribution of the RETN C-420G and G+299A SNPs. The study indicated that the SNP-420 heterozygous (CG) genotype (odds ratio [OR]=2.48, 95% CI 1.07-5.74, P=.03) and the SNP +299 heterozygous (GA) genotype (OR=6.5, 95% CI 1.77-24.18, P=.002) significantly increased the risk of colon cancer. A further analysis of the genotype combination of SNPs RETN C-420G and G+299A showed a larger increase in the colon cancer risk.

CONCLUSION

These preliminary results suggested a potential role for RETN C-420G and G+299A polymorphisms in the genetic predisposition to colon cancer disease.

Adipokines as a novel link between obesity and atherosclerosis

The traditional perception of adipose tissue as a storage organ of fatty acids has been replaced by the notion that adipose tissue is an active endocrine organ, releasing various adipokines that are involved in the pathogenesis of obesity-related metabolic disturbances. Obesity is a well-known risk factor for atherosclerosis, and accelerates atherosclerosis by many mechanisms such as increase in blood pressure and glucose level, abnormal lipid profiles, and systemic inflammation. Furthermore, growing evidence suggests that some adipokines directly mediate the process of atherosclerosis by influencing the function of endothelial cells, arterial smooth muscle cells, and macrophages in vessel walls. In obese patients, the secretion and coordination of such adipokines is abnormal, and the secretion of specific adipokines increases or decreases. Accordingly, the discovery of new adipokines and elucidation of their functions might lead to a new treatment strategy for metabolic disorders related to obesity, including cardiovascular diseases.

Chemerin levels as predictor of acute coronary events: a case-control study nested within the veterans affairs normative aging study

OBJECTIVE

Chemerin is a recently identified adipocytokine that has been positively correlated with the presence and severity of coronary artery disease (CAD). However, no studies have examined circulating chemerin levels as a predictor of acute coronary syndrome (ACS). The purpose of this study is to evaluate whether chemerin levels predict the onset of ACS.

MATERIALS/METHODS

We studied 90 men whose serum had been collected at least 2 years before the development of ACS, and 162 controls matched with the cases in a 1:2 fashion for age and year of collection. The mean age of the cohort was 66.3±9.6 years (range 34-84 years). Serum chemerin levels were measured with a commercially available enzyme-linked immunosorbent assay.

RESULTS

Age was positively associated with chemerin levels (r=0.39, p<0.001). Logistic regression analysis, adjusting for years since blood collection, demonstrated a null association between chemerin levels and the odds ratio for development of ACS (OR: 0.99, 95% CI [0.99-1.001]). This association remained null after adjusting for age (OR: 0.99 95% CI [0.99-1.001]).

CONCLUSIONS

Although cross-sectional and case-control studies suggest a positive association between chemerin levels and CAD, we demonstrate that chemerin levels do not predict the development of ACS.

Resistin levels are related to fat mass, but not to body mass index in children

The relationship of resistin levels with obesity remains unclear. The aim of this study was to determine resistin levels in prepubertal children and adolescents and evaluate their association with anthropometric parameters and body composition. The study population included 420 randomly selected 6-8-year-old children and 712 children aged 12-16 years. Anthropometric data were measured and body mass index (BMI) and waist-to-hip and waist-to-height ratios were calculated. Body composition was assessed using an impedance body composition analyzer. Serum resistin levels were determined using a multiplexed bead immunoassay. Resistin levels were not significantly different between sexes. No significant differences in serum resistin concentrations were found between obese, overweight, and normal weight children at any age, and no significant correlations were observed between resistin concentrations and weight or BMI. However, resistin levels showed a significant positive correlation with fat mass in 12-16-year-old children, particularly in girls. In addition to describing serum resistin levels in prepubertal children and adolescents, our study suggests that resistin is related to body fat rather than to BMI in adolescents.

PCSK9 and resistin at the crossroads of the atherogenic dyslipidemia

The atherogenic dyslipidemia is a pathophysiological lipid triad, composed of high triglycerides and low-density lipoprotein and low high-density lipoprotein. The dyslipidemia is highly prevalent in individuals who are obese, insulin resistant and those with Type 2 diabetes and is the major contributing factor to the high atherosclerotic cardiovascular disease risk in these subjects. The primary initiating event in atherogenic dyslipidemia development is the hepatic overproduction of very-low-density lipoprotein (VLDL). The intracellular and extracellular protein triggers of hepatic VLDL production were not known until the recent identification of the causal roles of PCSK9 and resistin. Both PCSK9 and resistin act in large part by targeting and reducing the hepatic degradation of VLDL apoB through distinctly different mechanisms. In the current review, we discuss both the individual roles and the interaction of these proteins in driving atherogenic dyslipidemia, and thus, atherosclerotic cardiovascular disease progression in humans. We further explore the important therapeutic implications of these findings.

Effects of bariatric surgery on adipokine-induced inflammation and insulin resistance

Over a third of the US population is obese and at high risk for developing type 2 diabetes, insulin resistance, and other metabolic disorders. Obesity is considered a chronic low-grade inflammatory condition that is primarily attributed to expansion and inflammation of adipose tissues. Indeed, adipocytes produce and secrete numerous proinflammatory and anti-inflammatory cytokines known as adipokines. When the balance of these adipokines is shifted toward higher production of proinflammatory factors, local inflammation within adipose tissues and subsequently systemic inflammation occur. These adipokines including leptin, visfatin, resistin, apelin, vaspin, and retinol binding protein-4 can regulate inflammatory responses and contribute to the pathogenesis of diabetes. These effects are mediated by key inflammatory signaling molecules including activated serine kinases such as c-Jun N-terminal kinase and serine kinases inhibitor κB kinase and insulin signaling molecules including insulin receptor substrates, protein kinase B (PKB, also known as Akt), and nuclear factor kappa B. Bariatric surgery can decrease body weight and improve insulin resistance in morbidly obese subjects. However, despite reports suggesting reduced inflammation and weight-independent effects of bariatric surgery on glucose metabolism, mechanisms behind such improvements are not yet well understood. This review article focuses on some of these novel adipokines and discusses their changes after bariatric surgery and their relationship to insulin resistance, fat mass, inflammation, and glucose homeostasis.

Central resistin enhances renal sympathetic nerve activity via phosphatidylinositol 3-kinase but reduces the activity to brown adipose tissue via extracellular signal-regulated kinase 1/2

Resistin is an adipokine, originally identified in adipose tissue, and its plasma levels are elevated in obesity. Characteristics of obesity include impaired metabolic regulation and cardiovascular dysfunction, such as increased sympathetic nerve activity (SNA) to the kidney and skeletal muscle vasculature. Resistin can affect energy homeostasis through central mechanisms that include reduced food intake and reduced thermogenesis, and can also increase lumbar SNA via a central action. The present study investigated: (i) the effect of centrally-administered resistin on SNA targeting the kidney and (ii) the intracellular signalling pathways mediating the changes in SNA innervating the kidney and brown adipose tissue (BAT) induced by resistin. Intracerebroventricular resistin (7 μg) injected into overnight fasted, anaesthetised rats induced a significant increase in renal SNA by approximately 40%. This response was prevented when phosphatidylinositol 3-kinase (PI3K) was inhibited by i.c.v. administration of LY294002 (5 μg). Resistin reduced BAT SNA and this response was delayed by 150 min when extracellular-regulated kinase (ERK)1/2 was inhibited by i.c.v. administration of U0126. The findings indicate that resistin increases renal SNA via PI3K and reduces BAT SNA via ERK1/2.

Resistin and cardiovascular disease

Resistin has been implicated in coronary atherosclerotic disease and congestive heart failure. Recent studies have extended its involvement in peripheral artery disease. Despite some controversial data, the mainstream clinical literature supports that resistin is associated with both coronary and peripheral artery diseases including ischemic stroke. In this review, the multiple roles of resistin as screening, diagnostic, and prognostic marker for cardiovascular disease are discussed. The independence of resistin in disease prediction and diagnosis appears complicated by its confounders, such as C-reactive protein. A clear-cut biomarker function of resistin in cardiovascular disease needs be clarified by additional large-scale, well-designed prospective studies.

Centrally administered resistin enhances sympathetic nerve activity to the hindlimb but attenuates the activity to brown adipose tissue

Resistin, an adipokine, is believed to act in the brain to influence energy homeostasis. Plasma resistin levels are elevated in obesity and are associated with metabolic and cardiovascular disease. Increased muscle sympathetic nerve activity (SNA) is a characteristic of obesity, a risk factor for diabetes and cardiovascular disease. We hypothesized that resistin affects SNA, which contributes to metabolic and cardiovascular dysfunction. Here we investigated the effects of centrally administered resistin on SNA to muscle (lumbar) and brown adipose tissue (BAT), outputs that influence cardiovascular and energy homeostasis. Overnight-fasted rats were anesthetized, and resistin (7 μg) was administered into the lateral cerebral ventricle (intracerebroventricular). The lumbar sympathetic nerve trunk or sympathetic nerves supplying BAT were dissected free, and nerve activity was recorded. Arterial blood pressure, heart rate, body core temperature, and BAT temperature were also recorded. Responses to resistin or vehicle were monitored for 4 h after intracerebroventricular administration. Acutely administered resistin increased lumbar SNA but decreased BAT SNA. Mean arterial pressure and heart rate, however, were not significantly affected by resistin. BAT temperature was significantly reduced by resistin, and there was a concomitant fall in body temperature. The findings indicate that resistin has differential effects on SNA to tissues involved in metabolic and cardiovascular regulation. The decreased BAT SNA and the increased lumbar SNA elicited by resistin suggest that it may contribute to the increased muscle SNA and reduced energy expenditure observed in obesity and diabetes.

Matrix metalloproteinases modulated by protein kinase Cε mediate resistin-induced migration of human coronary artery smooth muscle cells

BACKGROUND

Emerging evidence showed that resistin induces vascular smooth muscle cell (VSMC) migration, a critical step in initiating vascular restenosis. Adhesion molecule expression and cytoskeletal rearrangement have been observed in this progress. Given that matrix metalloproteinases (MMPs) also regulate cell migration, we hypothesized that MMPs may mediate resistin-induced VSMC migration.

METHODS

Human VSMCs were treated with recombinant human resistin at physiologic (10 ng/mL) and pathologic (40 ng/mL) concentrations for 24 hours. Cell migration was determined by the Boyden chamber assay. MMP and tissue inhibitor metalloproteinase (TIMP) mRNA and protein levels were measured with real-time PCR and ELISA. MMP enzymatic activity was measured by zymography. In another experiment, neutralizing antibodies against MMP-2 and MMP-9 were coincubated with resistin in cultured VSMCs. The regulation of MMP by protein kinase C (PKC) was determined by εV1-2, a selective PKCε inhibitor.

RESULTS

Resistin-induced smooth muscle cell (SMC) migration was confirmed by the Boyden chamber assay. Forty nanograms/milliliter resistin increased SMC migration by 3.7 fold. Additionally, resistin stimulated MMP-2 and -MMP9 mRNA and protein expressions. In contrast, the TIMP-1 and TIMP-2 mRNA levels were inhibited by resistin. Neutralizing antibodies against MMP-2 and MMP-9 effectively reversed VSMC migration. Furthermore, resistin activated PKCε, but selective PKCε inhibitor suppressed resistin-induced MMP expression, activity, and cell migration.

CONCLUSIONS

Our study confirmed that resistin increased vascular smooth muscle cell migration in vitro. In terms of mechanism, resistin-stimulated cell migration was associated with increased MMP expression, which was dependent on PKCε activation.

Association of adiponectin, resistin, and vascular inflammation: analysis with 18F-fluorodeoxyglucose positron emission tomography

OBJECTIVE

Adiponectin and resistin are adipokines that are linked to obesity, inflammation, and atherosclerosis. (18)F-Fluorodeoxyglucose (FDG) positron emission tomography is a promising imaging technique that can be used to evaluate vascular inflammation.

METHODS AND RESULTS

We measured adiponectin and resistin levels, as well as traditional cardiovascular risk factors, in 60 obese subjects and 60 nonobese controls. In addition, we compared carotid intima-media thickness and target-to-background ratio (TBR) measured using (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography. The mean TBR values were significantly higher in the obese group compared with normal subjects, although their mean carotid intima-media thickness levels were not significantly different. Serum adiponectin levels showed a significant negative correlation with mean TBR values (r = -0.215, P = 0.020), whereas resistin levels were positively correlated with mean TBR values (r = 0.214, P = 0.021). Multiple linear regression analysis showed that mean TBR values were independently associated with body mass index, high-sensitivity C-reactive protein, and resistin levels (R(2) = 0.308).

CONCLUSIONS

Adiponectin and resistin may be useful as biomarkers to reflect vascular inflammation. In particular, resistin levels were independently associated with vascular inflammation even after adjusting for other cardiovascular risk factors.

Resistin contributes to neointimal formation via oxidative stress after vascular injury

Resistin may play a major potential role in vascular remodelling and may contribute to atherogenesis. However, the role of VSMC (vascular smooth muscle cell)-derived resistin in neointimal formation is not well understood. We hypothesize that endogenous resistin derived from VSMCs may contribute to neointimal formation after vascular injury. VSMCs from thoracic aorta of adult Wistar rats were cultured. The carotid artery from adult Wistar rats was injured by balloon catheter. Resistin significantly increased migration and proliferation of VSMCs. Resistin siRNA (small interfering RNA) and resistin antibody significantly inhibited migration and proliferation of VSMCs induced by conditioned medium from stretched VSMCs. Resistin protein and mRNA expression significantly increased at 14 days after carotid injury. Resistin siRNA and NAC (N-acetylcysteine) significantly reduced resistin protein and mRNA expression induced by balloon injury. Carotid artery injury increased ROS (reactive oxygen species) production. Treatment with NAC and resistin siRNA decreased ROS production. The neointimal area was significantly increased after carotid injury and was significantly reduced by resistin siRNA and NAC. In conclusion, resistin increases migration and proliferation of VSMCs, and expression of resistin in carotid artery significantly increases after injury. Resistin siRNA attenuates neointimal formation after carotid injury partly through an antioxidative mechanism. Resistin may play a pivotal role in the pathogenesis of neointimal thickening after mechanical injury.

The effect of aerobic versus strength-based training on high-sensitivity C-reactive protein in older adults

Increased levels of inflammatory markers, namely, high-sensitive C-reactive protein (hs-CRP), have been associated with several chronic diseases including atherosclerosis, type 2 diabetes and hypertension. Forty-five women and men aged >64 years participated in the study and were randomly assigned to two exercise intervention groups and a non-exercising control group. The participants assigned to the exercising groups followed a 16-week exercise protocol based either on aerobic training (AT) or strength training (ST) followed by a further 16 weeks off-training period. The control group (C) remained sedentary throughout the study. Evaluation of body mass, BMI, waist circumference, aerobic endurance, lower-body strength, upper-body strength, triglycerides, total cholesterol, LDL-cholesterol, HDL-cholesterol and hs-CRP were performed at baseline, after 16 weeks (post-training for the exercise groups) and at 32 weeks (follow-up). Both, AT and ST groups significantly increased functional fitness at the end of the exercise programs when compared to baseline values. hs-CRP concentrations were maintained throughout the study for the C group, while decreasing 10% at 16 weeks and 51% at 32 weeks for the AT group. In the ST group the hs-CRP concentrations decreased by 11 and 39% at 16 and 32 weeks, respectively. Decreases in hs-CRP concentrations were statistically significant for the AT and ST groups at the 32-week evaluation when compared to baseline. Reduction in hs-CRP concentrations seemed to be associated with strength gains and adiposity loss.

Resistin as a cardiovascular and atherosclerotic risk factor and uremic toxin

Resistin is a 12.5 kDa protein originally found to be secreted by mouse adipocytes. Whereas in rodents adipose tissue is the main source of resistin, in humans resistin is expressed primarily in macrophages. In a variety of pathophysiologic states, particularly in type 2 diabetes mellitus and in chronic kidney disease, the serum concentration of resistin is increased. Resistin reduces the glucose uptake in adipose tissue and skeletal muscle cells and may be involved in insulin resistance. A positive correlation between resistin levels and inflammatory markers has been described. Resistin has a potential role in cardiovascular disease and may contribute to an increased atherosclerotic risk by modulating the activity of endothelial cells. We recently found that resistin in concentrations measured in uremia is able to interfere with the chemotactic movement and the oxidative burst of neutrophils, cells of the first-line nonspecific immune defense. Therefore, resistin may also contribute to the disturbed immune response and as a consequence to the increased risk of infections in uremic and diabetic subjects.

Serial plasma concentrations of adiponectin, leptin, and resistin during therapy in children with acute lymphoblastic leukemia

PURPOSE

To investigate adipocytokine secretion, at diagnosis and during chemotherapy in children with the acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

Serial measurements (6/patient) of the anti-inflammatory cytokine adiponectin and the proinflammatory adipocytokines leptin and resistin were performed at diagnosis and in nearly the entire period of therapy (up to 21 months), in 9 patients with ALL aged 2 to 7 years (median 4.3 y). Body mass index and leukemic burden were estimated at the same time points and correlated with adipocytokine levels. Nine healthy children matched for age, sex, and body mass index were used as controls.

RESULTS

At diagnosis, mean adiponectin levels were low (P<0.001) and mean leptin and resistin levels were high, compared with controls (P<0.001). During maintenance phase, adiponectin increased significantly (P=0.024), whereas leptin and resistin decreased (P=0.018 and P=0.020, respectively), compared with baseline values. However, adiponectin, despite its progressive increase, remained at lower levels toward the end of the maintenance phase, compared with controls, (P<0.001). Delta (final-baseline) mean adiponectin was negatively correlated with leukemic burden (P=0.019), whereas delta mean leptin and resistin were positively correlated with it (P=0.011 and P=0.031, respectively).

CONCLUSIONS

Low-plasma adiponectin and high leptin and resistin level are present at the ALL diagnosis. Adipocytokines alterations are progressively restored during therapy.

Adipokine signaling in inflammatory bowel disease

While the incidence of inflammatory bowel disease (IBD) is still increasing, the etiology has not finally been dissected. The main hypothesis suggests that the mucosal immune system is hyperresponsive to dietary factors and commensal bacteria in genetically predisposed individuals. Burrill Crohn himself described a local hypertrophy of the mesenteric fat tissue adjacent to the segments of inflamed intestine. In addition, more recent data indicate altered local expression and serum levels of some adipocyte-derived mediators (adipokines) with immune-modulating capacities in IBD. This review focuses on the role of adipose tissue and adipokines in the immune system, with particular focus on the mucosal immune system. The available data will serve to establish a working hypothesis on how the mesenteric fat tissue contributes to the pathogenesis of Crohn's disease.

Macrophage-derived human resistin exacerbates adipose tissue inflammation and insulin resistance in mice

Resistin is an adipokine that contributes to insulin resistance in mice. In humans, however, studies investigating the link between resistin and metabolic disease are conflicting. Further complicating the matter, human resistin is produced mainly by macrophages rather than adipocytes. To address this important issue, we generated mice that lack adipocyte-derived mouse resistin but produce human resistin in a pattern similar to that found in humans, i.e., in macrophages (humanized resistin mice). When placed on a high-fat diet, the humanized resistin mice rapidly developed accelerated white adipose tissue (WAT) inflammation, leading to increased lipolysis and increased serum free fatty acids. Over time, these mice accumulated lipids, including diacylglycerols, in muscle. We found that this resulted in increased Pkcq pathway activity, leading to increased serine phosphorylation of Irs-1 and insulin resistance. Thus, although the site of resistin production differs between species, human resistin exacerbates WAT inflammation and contributes to insulin resistance.

White adipose tissue as endocrine organ and its role in obesity

Due to the public health problem represented by obesity, the study of adipose tissue, particularly of the adipocyte, is central to the understanding of metabolic abnormalities associated with the development of obesity. The concept of adipocyte as endocrine and functional cell is not totally understood and can be currently defined as the capacity of the adipocyte to sense, manage, and send signals to maintain energy equilibrium in the body. Adipocyte functionality is lost during obesity and has been related to adipocyte hypertrophy, disequilibrium between lipogenesis and lipolysis, impaired transcriptional regulation of the key factors that control adipogenesis, and lack of sensitivity to external signals, as well as a failure in the signal transduction process. Thus, dysfunctional adipocytes contribute to abnormal utilization of fatty acids causing lipotoxicity in non-adipose tissue such as liver, pancreas and heart, among others. To understand the metabolism of the adipocyte it is necessary to have an overview of the developmental process of new adipocytes, regulation of adipogenesis, lipogenesis and lipolysis, endocrine function of adipocytes and metabolic consequences of its dysfunction. Finally, the key role of adipose tissue is shown by studies in transgenic animals or in animal models of diet-induced obesity that indicate the contribution of adipose tissue during the development of metabolic syndrome. Thus, understanding of the molecular process that occurs in the adipocyte will provide new tools for the treatment of metabolic abnormalities during obesity.