Resistin, an adipokine with potent proinflammatory properties

Elevated resistin levels may regulate high mobility group box 1 expression in Guillain-Barré syndrome

Interactions among cytokines have important roles in the inflammatory processes underlying Guillain-Barré syndrome (GBS). Resistin and high mobility group box 1 (HMGB1) are involved in many inflammatory processes. This study examined 51 GBS patients, and found that serum resistin levels were elevated in 51 patients with GBS and correlated with HMGB1 levels. In vitro, resistin induced the release of HMGB1, interleukin (IL)-1β, and IL-6 in THP-1 macrophages. This process was dependent on activation of p38 mitogen-activated protein kinase and NF-κB signaling pathways. These results suggest that signaling between resistin and HMGB1 might be a potential therapeutic target in GBS.

Evidence of an anti-inflammatory toll-like receptor 9 (TLR 9) pathway in adipocytes

Adipocytes express various pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) and actively participate in anti-bacterial and anti-viral host defence. Obesity is associated with adipose tissue PRR expression. The potential role of Toll-like receptor 9 (TLR9) in adipocytes has not yet been investigated. Here, we evaluated TLR9 expression during adipocyte differentiation (AD) of 3T3-L1 adipocytes, in primary murine adipocytes and in different murine and human adipose tissue depots by real-time PCR, immunocytochemistry and immunohistochemistry. TLR9 expression was inhibited using specific siRNA-mediated knockdown, and TLR9 signaling was induced using specific class A, B and C agonistic CpG-oligodeoxynucleotide (ODN) treatment vs ODN controls in 3T3-L1 adipocytes and in primary murine adipocytes from Tlr9wt/wt vs Tlr9-/- mice. We found that TLR9 gene expression is induced during AD and that TLR9 protein is expressed in murine gonadal and human visceral adipocytes. AD depends on intact TLR9 expression. Tlr9-/- mice demonstrate significantly reduced adiponectin serum levels, while siRNA-mediated TLR9 knockdown led to reduced adiponectin mRNA expression in adipocytes. TLR9 ligands (CpG-ODNs) inhibit pro-inflammatory resistin secretion in mature 3T3-L1 adipocytes. Tlr9-/- as compared to Tlr9wt/wt adipocytes exhibit increased resistin and MCP1 secretion and reduced adiponectin secretion into cell culture supernatants, while TLR9 ligands (ODNs) show differential effects in Tlr9-/- vs Tlr9wt/wt primary murine adipocytes. TLR9 expression is significantly increased in visceral compared to subcutaneous adipose tissue depots in non-diabetic obese patients and correlates with systemic resistin levels in a compartment-specific manner. Thus, adipocytic TLR9 is a putative, new protective factor during (obesity-associated) adipose tissue inflammation.

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.

An Update on the Emerging Role of Resistin on the Pathogenesis of Osteoarthritis

Background

Resistin may be involved in the pathogenesis of osteoarthritis (OA), but a systematic understanding of the role of resistin in OA is lacking.

Methods

We reviewed studies that evaluated the role of resistin in OA. The expression levels of resistin in vitro experiments and OA/rheumatoid arthritis (RA) patients were analyzed. We also studied potential resistin receptors and the signaling pathways that these receptors activate, ultimately leading to cartilage degeneration.

Results

Resistin levels in both the serum and synovial fluid were higher in OA and RA patients than in healthy subjects. Overall, resistin levels are much higher in serum than in synovial fluid. In human cartilage, resistin induces the expression of proinflammatory factors such as degradative enzymes, leading to the inhibition of cartilage matrix synthesis, perhaps by binding to Toll-like receptor 4 and the adenylyl cyclase-associated protein 1 receptor, which then activates the p38-mitogen-activated phosphate kinase, protein kinase A–cyclic AMP, nuclear factor-κB, and C/enhancer-binding protein β signaling pathways.

Conclusion

Resistin levels are higher in OA patients than in healthy controls; however, the precise role of resistin in the pathogenesis of OA needs to be studied further. Resistin may be a novel therapeutic target in OA in the future.

Resistin-Inhibited Neural Stem Cell-Derived Astrocyte Differentiation Contributes to Permeability Destruction of the Blood-Brain Barrier

Neuroinflammation is an important part of the development of neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's and amyotrophic lateral sclerosis. Inflammatory factors destroy the balance of the microenvironment, which results in changes in neural stem cell differentiation and proliferation behaviour. However, the mechanism underlying inflammatory factor-induced NSC behavioural changes is not clear. Resistin is a proinflammatory and adipogenic factor and is involved in several human pathology processes. The neural stem cell microenvironment changes when the concentration of resistin in the brain during an inflammatory response disease increases. In the present study, we explored the effect and mechanism of resistin on the proliferation and differentiation of neural stem cells. We found that intracerebroventricular injection of resistin induced a decrease in GFAP-positive cells in mice by influencing NSC differentiation. Resistin significantly decreased TEER and increased permeability in an in vitro blood-brain barrier model, which is consistent with the results of an HBMEC-astrocyte coculture system. Resistin-inhibited astrocyte differentiation is mediated through TLR4 on neural stem cells. To our knowledge, this is the first study reporting the effect of resistin on neural stem cells. Our findings shed light on resistin-involved neural stem cell degeneration mechanisms.

Myokine-adipokine cross-talk: potential mechanisms for the association between plasma irisin and adipokines and cardiometabolic risk factors in Mexican children with obesity and the metabolic syndrome

BACKGROUND

Adipokines and the myokine irisin, involved in mechanisms associated with obesity and metabolic syndrome (MS), are understudied in the pediatric population.

OBJECTIVE

To investigate the relationship between irisin, and leptin, resistin, adiponectin, adipsin, anthropometric and cardiovascular risk factors in Mexican children.

METHODS

A cross-sample of 126 Mexican children aged 6-12 years old were classified as normal weight (n = 46), obese (n = 40), and MS (n = 40) according to CDC's and Cook's age-modified criteria for obesity and MS. Anthropometric parameters and blood pressure were determined and percentiles calculated for age and gender. Irisin, leptin, adiponectin, adipsin, resistin, triglycerides, glucose, high-density lipoprotein cholesterol (HDL-c) levels, and physical activity were determined. Statistical tests for differences between groups, correlation, and multiple regression analyses were performed.

RESULTS

Irisin plasma levels were significantly lower in the obese (6.08 [4.68-6.65]) and MS groups (6.46 [5.74-7.02]) compared with the normal-weight group (8.05 [7.24-8.94]) (p < 0.001). Irisin levels were not influenced by age or gender, but significant dispersion was observed in obese girls (95% CI median [2.29-6.30]). Leptin, resistin, and adipsin levels were significantly increased in the obese and MS groups. Lean-fat ratio was significantly higher in the NW group. Irisin correlated negatively with leptin (- 0.310), resistin (- 0.389), adipsin (- 0.362), BMI% (-0.472), WC% (- 0.453), BMI z-score (- 0.496), fat free mass (- 0.257), fat percentage (- 0.532), fat mass (- 0.515), triglycerides (- 0.291), the number of cardiometabolic risk factors (- 0.443) (p < 0.001); positively with lean-fat ratio (0.489) and HDL-c (0.328) (p < 0.001) and none with physical activity (p < 0.001). Following stepwise multiple linear regression analysis, the lean-fat ratio was the only determinant of irisin levels (B = 1.168, p < 0.001).

CONCLUSIONS

Lean-fat ratio, more than the absolute amount of muscle or fat mass, as well as potential myokine-adipokine cross-talk mechanisms may explain the lower irisin levels in children with obesity and MS, through blunted compensatory responses interfering with tissue-dependent irisin secretion, contributing to a continuous deleterious effect cycle.

Obesity, adipocyte hypertrophy, fasting glucose, and resistin are potential contributors to nonalcoholic fatty liver disease in South Asian women

Purpose: Nonalcoholic fatty liver disease (NAFLD) is often referred to as the hepatic manifestation of the metabolic syndrome. The relationship between body weight, NAFLD, and insulin resistance is not well characterized in humans. Additionally, it is unclear why South Asians develop these complications at lower levels of obesity compared to their Western counterparts. Patients and methods: To address this question, we performed a cross-sectional study using a convenience sample of Sri Lankan adult females (n=34) and collected anthropometric data, adipose tissue specimens (for histology), and fasted serum samples (for metabolic and inflammatory markers). Hepatic steatosis was assessed by ultrasound scanning and used to classify participants as NAFL 0, NAFL 1, and NAFL 2. Results: Waist circumference significantly increased with increasing NAFL grade. Participants with NAFL had significantly higher body mass index, hip circumference, and fasting plasma glucose, as well as a higher mean adipocyte area in both abdominal subcutaneous and visceral areas, indicating a higher degree of adipocyte hypertrophy associated with fatty liver. There were, however, no differences in measures of dyslipidemia. Of the multiple adipokines measured, resistin was the only proinflammatory adipokine significantly elevated in NAFL 2. Conclusion: These findings indicate that measures of adiposity, fasting serum glucose, and resistin may be important indicators of NAFLD in South Asian women.

Effects of metformin on metabolism of white and brown adipose tissue in obese C57BL/6J mice

BACKGROUND

To investigate effects of metformin on the regulation of proteins of white adipose tissue (WAT) and brown adipose tissue (BAT) in obesity and explore the underlying mechanisms on energy metabolism.

METHODS

C57BL/6J mice were fed with normal diet (ND, n = 6) or high-fat diet (HFD, n = 12) for 22 weeks. HFD-induced obese mice were treated with metformin (MET, n = 6). After treatment for 8 weeks, oral glucose tolerance test (OGTT) and hyperinsulinemic-euglycemic clamp were performed to evaluate the improvement of glucose tolerance and insulin sensitivity. Protein expressions of WAT and BAT in mice among ND, HFD, and MET group were identified and quantified with isobaric tag for relative and absolute quantification (iTRAQ) coupled with 2D LC-MS/MS. The results were analyzed by MASCOT, Scaffold and IPA.

RESULTS

The glucose infusion rate in MET group was increased significantly compared with HFD group. We identified 4388 and 3486 proteins in WAT and BAT, respectively. As compared MET to HFD, differential expressed proteins in WAT and BAT were mainly assigned to the pathways of EIF2 signaling and mitochondrial dysfunction, respectively. In the pathways, CPT1a in WAT, CPT1b and CPT2 in BAT were down-regulated by metformin significantly.

CONCLUSIONS

Metformin improved the body weight and insulin sensitivity of obese mice. Meanwhile, metformin might ameliorate endoplasmic reticulum stress in WAT, and affect fatty acid metabolism in WAT and BAT. CPT1 might be a potential target of metformin in WAT and BAT.

Molecular Mechanisms Underlying Obesity-Induced Hypothalamic Inflammation and Insulin Resistance: Pivotal Role of Resistin/TLR4 Pathways

Low-grade inflammation and insulin resistance are among the clinical features of obesity that are thought to promote the progressive onset of type 2 diabetes. However, the underlying mechanisms linking these disorders remain not fully understood. Recent reports pointed out hypothalamic inflammation as a major step in the onset of obesity-induced insulin resistance. In light of the increasing prevalence of obesity and T2D, two worldwide public health concerns, deciphering mechanisms implicated in hypothalamic inflammation constitutes a major challenge in the field of insulin-resistance/obesity. Several clinical and experimental studies have identified resistin as a key hormone linking insulin-resistance to obesity, notably through the activation of Toll Like Receptor (TLR) 4 signaling pathways. In this review, we present an overview of the molecular mechanisms underlying obesity-induced hypothalamic inflammation and insulin resistance with peculiar focus on the role of resistin/TLR4 signaling pathway.

Oxidative stress and adipokine levels were significantly correlated in diabetic patients with hyperglycemic crises

BACKGROUND

To investigate the relationship between blood adipokine level and oxidative stress in diabetic patients with hyperglycemic crises before and after treatment.

METHODS

We measured superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, total antioxidant capacity (TAC), and levels of 8-iso-prostaglandin F2α (8-iso-PGF2α), adiponectin, leptin, and resistin in 63 diabetic patients with hyperglycemic crises.

RESULTS

Prior to treatment, patients with hyperglycemic crises had significantly lower serum SOD activity, TAC, and adiponectin and leptin levels, and higher serum levels of MDA, 8-iso-PGF2α, and resistin compared with the healthy control individuals (all at P < 0.05). After treatment, SOD, TAC, adiponectin, and leptin levels increased significantly, while MDA, 8-iso-PGF2α, and resistin levels decreased significantly (all at P < 0.05) in the patients.

CONCLUSIONS

Diabetic patients with hyperglycemic crises have increased oxidative stress, which is associated with serum adipokine abnormalities; improved oxidative stress after treatment suggests that oxidative stress may serve as target and/or indicator for the treatment of hyperglycemic crises.

Physical activity increases the resistin concentration in hemodialyzed patients without metabolic syndrome

BACKGROUND

Resistin (RES) concentration increases in end-stage renal disease patients. However, there have been no studies defining the role of physical activity in RES concentrations in hemodialyzed (HD) patients. This study was aimed to determine metabolic and inflammatory effects, including RES, of 4-week supervised rehabilitation program in HD patients, with or without metabolic syndrome (MS).

METHODS

The study was completed by 28 patients aged 56.9±13.3 years ( x ¯ ± SD ) who were HD for 50.6±73.4 months, and 30 controls aged 61.5±8.3 years with normal renal function. Both the groups were divided into two subgroups with respect to MS. Individualized supervised rehabilitation program based on physiotherapy, including exercises, was provided to each subject for 4 weeks. Baseline and post-intervention complete blood count, glycated hemoglobin (HbA1c) and levels of serum RES, leptin, adiponectin, cystatin C, erythropoietin, high sensitivity C-reactive protein (hs-CRP), tumor necrosis factor alpha (TNF-α), interleukin-6, transforming growth factor- β1, plasminogen activator inhibitor-1 homocysteine, insulin, albumin, parathyroid hormone (PTH), and phosphorus were measured.

RESULTS

Compared to controls, HD patients showed higher baseline leucocytes count and higher serum concentrations of RES, leptin, cystatin C, hs-CRP, TNF-α, homocysteine, phosphorus, PTH while hemoglobin, glucose, and albumin concentrations. A positive correlation between serum albumin and RES concentrations was observed in HD patients. Post-intervention RES increase was observed in HD patients without MS (post-intervention 34.22±8.89 vs baseline 30.16±11.04 ng/mL; P=0.046) while no change was observed in patients with MS and in the control group.

CONCLUSION

MS modifies a RES response to the rehabilitation program in HD patients.

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.

Adipocytokines in Rheumatoid Arthritis: The Hidden Link between Inflammation and Cardiometabolic Comorbidities

Rheumatoid arthritis is a chronic autoimmune disease affecting typically synovial joints and leading to progressive articular damage, disability, and reduced quality of life. Despite better recent therapeutic strategies improving long-term outcomes, RA is associated with a high rate of comorbidities, infections, malignancies, and cardiovascular disease (CVD). Remarkably, some well-known pathogenic proinflammatory mediators in RA, such as interleukin-1β (IL-1β) and tumor necrosis factor (TNF), may play a pivotal role in the development of CVD. Interestingly, different preclinical and clinical studies have suggested that biologic agents commonly used to treat RA patients may be effective in improving CVD. In this context, the contribution of adipocytokines has been suggested. Adipocytokines are pleiotropic molecules, mainly released by white adipose tissue and immune cells. Adipocytokines modulate the function of different tissues and cells, and in addition to energy homeostasis and metabolism, amplify inflammation, immune response, and tissue damage. Adipocytokines may contribute to the proinflammatory state in RA patients and development of bone damage. Furthermore, they could be associated with the occurrence of CVD. In this study, we reviewed available evidence about adipocytokines in RA, because of their involvement in disease activity, associated CVD, and possible biomarkers of prognosis and treatment outcome and because of their potential as a possible new therapeutic target.

Adipocytokine Involvement in Innate Immune Mechanisms

The innate immune response is defined as an immensely complex and sophisticated process aimed at defending the organism against any disturbance in the body homeostasis, including invading pathogens. It requires a close cooperation of a vast amount of different cell types, recognized as inflammatory migrating cells, as well as stationary cells that form tissues. Moreover, innate immune mechanisms require an efficient functioning of various humoral components that exert a significant impact on physiological and pathological processes. Apart from commonly mentioned humoral factors, this group also includes a family of proteins known as adipocytokines that may act as pro- or anti-inflammatory agents or act both ways. Leptin, predominantly characterized as a proinflammatory adipokine, plays a crucial role in endothelium remodeling and regulation, as well as in cell survival and production of numerous cytokines. Adiponectin, similar to leptin, acts on the endothelial cells and the phagocytic properties of immune cells; however, it exerts an anti-inflammatory impact. Resistin has a documented role in the control of angiogenesis and stimulation of proinflammatory mediator generation and release. Furthermore, there are adipokines, ie, visfatin and chemerin, whose participation in the inflammatory processes is ambiguous. This review focuses on the current knowledge on the extensive role of selected adipokines in innate immune response.

Periodontal, metabolic, and cardiovascular disease: Exploring the role of inflammation and mental health

Previous evidence connects periodontal disease, a modifiable condition affecting a majority of Americans, with metabolic and cardiovascular morbidity and mortality. This review focuses on the likely mediation of these associations by immune activation and their potential interactions with mental illness. Future longitudinal, and ideally interventional studies, should focus on reciprocal interactions and cascading effects, as well as points for effective preventative and therapeutic interventions across diagnostic domains to reduce morbidity, mortality and improve quality of life.

Meta-analysis of circulating adiponectin, leptin, and resistin levels in systemic sclerosis

OBJECTIVE

We aimed to evaluate the relationship between circulating blood adipokine levels and systemic sclerosis (SSc).

METHODS

We conducted a meta-analysis on serum/plasma adiponectin, leptin, or resistin levels in patients with SSc and controls, and performed a subgroup analysis based on ethnicity and/or disease type.

RESULTS

Eleven studies (511 patients with SSc and 341 controls) were included in the meta-analysis. Meta-analysis revealed that adiponectin levels were significantly lower in patients with SSc than in controls (standardized mean differences [SMD] = -0.638; 95 % confidence intervals [CI] = -1.154, -0.122; P = 0.015). Stratification by ethnicity showed a low adiponectin level associated with SSc in Caucasians (SMD = -0.439; 95 % CI = -1.092, -0.213; P = 0.187) and Asians (SMD = -1.006; 95 % CI = -2.031, -0.019; P = 0.055), although this result was not statistically significant. Stratification by disease type revealed that the adiponectin level was significantly lower in the diffuse SSc, but not limited SSc, group than in the control (diffuse: SMD = -1.445; 95 % CI = -2.276, -0.614; P = 0.001; limited: SMD = 0.188; 95 % CI = -0.064, 0.439; P = 0.144). Meta-analysis showed no association between leptin levels and SSc (SMD = -0.029; 95 % CI = -1.362, 1.304; P = 0.966), and no association between resistin levels and SSc (SMD = 0.202; 95 % CI = -0.091, 0.496; P = 0.177).

CONCLUSIONS

Our meta-analysis revealed a significantly lower circulating adiponectin level in patients with SSc than in controls. This difference was apparent in the diffuse type of SSc, but not in the limited type. However, circulating leptin and resistin levels were not different between patients with SSc and healthy controls.

Association between rs1862513 and rs3745367 Genetic Polymorphisms of Resistin and Risk of Cancer: A Meta-Analysis

The present study aimed to assess any associations between resistin gene (RETN) polymorphisms and cancer susceptibility by conducting a meta-analysis. A comprehensive literature search was performed with PubMed, Web of Science, Scopus and Google Scholar for relevant studies published before April 2018. For the rs1862513 polymorphism, data from 9 studies covering 1,951 cancer patients and 2,295 healthy controls were included in this meta-analysis. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Our meta-analysis revealed that this RETN polymorphism significantly increased the risk of cancer in codominant (OR=1.23, 95% CI= 1.01-1.50, p=0.04, CG vs CC; and OR=1.25, 95% CI= 1.03-1.53, p=0.03, GG vs CC), dominant (OR=1.19, 95% CI= 1.05-1.35, p=0.006, CG+GG vs CC), and allele (OR=1.14, 95% CI= 1.00-1.30, p=0.04, G vs C) inheritance genetic models. Stratification analysis by cancer type revealed that the rs1862513 variant significantly increased the risk of colorectal and breast cancer, and that cancer overall in Caucasians (OR=1.22, 95% CI= 1.04-1.43, p=0.02, CG+GG vs CC; OR=1.18, 95% CI= 1.04-1.34, p=0.01, G vs C). The data revealed no correlation between the rs3745367 polymorphism and cancer risk. Further well-designed studies with larger sample sizes and different ethnicities are warranted to validate the present findings.

Resistin effects on pancreatic cancer progression and chemoresistance are mediated through its receptors CAP1 and TLR4

Resistin, secreted by macrophages in tumor microenvironment, has never been investigated in pancreatic cancer models, despite a vibrant tumor microenvironment around pancreatic tumors. We evaluated serum resistin levels in healthy individuals versus pancreatic cancer patients representing different tumor grades. In vitro mechanistic analysis involved MiaPaCa-2 and SW1990 cells. Resistin signaling depends on binding of resistin to its cognitive receptors. Therefore, we silenced adenylyl cyclase-associated protein 1 (CAP1) and toll-like receptor 4 (TLR4), its two known receptors, individually as well as in combination, by short hairpin RNA (shRNA). Effect of resistin on cell proliferation, migration, invasion, cell cycle, and sensitivity to gemcitabine was studied without or with silencing of resistin receptors CAP1 and/or TLR4. The results were also confirmed in vivo in mice xenografted with MiaPaCa-2 cells without or with receptor silencing. We report high resistin levels in pancreatic cancer patients which correlate positively with tumor grades. We observed a marked reduction in the resistin-induced proliferation, migration, invasion, and cell cycle of pancreatic cancer cells MiaPaCa-2 and SW1990 when the receptors were silenced. The results were confirmed in vivo wherein resistin effects were significantly attenuated in MiaPaCa-2 xenografts with silenced receptors. The combined silencing of CAP1 and TLR4 was found to be most effective in vitro and in vivo. We found activation of STAT3 by resistin in vivo and in vitro which was dependent on the presence of CAP1 and TLR4. Further, resistin was found to induce resistance to gemcitabine through its receptors. Our results describe novel functional roles of resistin with implications toward a better understanding of pancreatic tumor microenvironment.

Perivascular adipose tissue (PVAT) in atherosclerosis: a double-edged sword

Perivascular adipose tissue (PVAT), the adipose tissue that surrounds most of the vasculature, has emerged as an active component of the blood vessel wall regulating vascular homeostasis and affecting the pathogenesis of atherosclerosis. Although PVAT characteristics resemble both brown and white adipose tissues, recent evidence suggests that PVAT develops from its own distinct precursors implying a closer link between PVAT and vascular system. Under physiological conditions, PVAT has potent anti-atherogenic properties mediated by its ability to secrete various biologically active factors that induce non-shivering thermogenesis and metabolize fatty acids. In contrast, under pathological conditions (mainly obesity), PVAT becomes dysfunctional, loses its thermogenic capacity and secretes pro-inflammatory adipokines that induce endothelial dysfunction and infiltration of inflammatory cells, promoting atherosclerosis development. Since PVAT plays crucial roles in regulating key steps of atherosclerosis development, it may constitute a novel therapeutic target for the prevention and treatment of atherosclerosis. Here, we review the current literature regarding the roles of PVAT in the pathogenesis of atherosclerosis.

Association of visceral adiposity and its longitudinal increase with the risk of diabetes in Chinese adults: A prospective cohort study

OBJECTIVE

A Chinese visceral adiposity index (CVAI) was recently established to estimate the visceral fat area in Chinese adults. This study aimed to investigate the risk of incident prediabetes and diabetes in relation to visceral adiposity calculated by CVAI.

METHODS

A total of 2558 subjects with normal plasma glucose levels from the Shanghai Changfeng Study were enrolled in a prospective cohort study. The independent associations of basal visceral fat area by CVAI and its longitudinal change with incident prediabetes and diabetes were identified using Cox regression analyses.

RESULTS

During an average of 4.4 years of follow-up, 546 (21.3%) and 99 (3.9%) of 2558 nondiabetic subjects developed prediabetes and diabetes, respectively. Visceral fat area by CVAI and its longitudinal increase were independently associated with incident prediabetes and diabetes in Chinese adults. In a multivariable-adjusted regression model, CVAI, as well as its annual change, was the strongest independent predictor of incident prediabetes (HR, 1.383 [1.162-1.647]) and diabetes (HR, 1.607 [1.092-2.364]) compared with other estimates of obesity (BMI and waist circumference). Receiver operating characteristic curve analyses showed that CVAI had better performance than BMI and waist circumference for the prediction of prediabetes and diabetes in Chinese adults.

CONCLUSIONS

Visceral adiposity plays a pivotal role in the pathogenesis of diabetes, and the visceral adiposity estimated by CVAI is superior to the traditional estimates of obesity for the prediction of incident prediabetes and diabetes in Chinese adults.

The role of adipose tissue in the pathogenesis of Crohn's disease

Crohn's disease (CD) is a chronic, immune system-mediated inflammatory disease affecting gastrointestinal (GI) tract. The pathogenesis of the intestinal lesions is not entirely explained and understood: excessive activation of the immune system may come as a result of the interaction of environmental, genetic and infectious factors and the mediation of abnormal intestinal flora. The main objective of the current study is to further identify the role of adipose tissue in the pathogenesis of CD. Alterations in body fat distribution, accumulation of intra-abdominal white adipose tissue (WAT) and mesenteric obesity are well-known features of CD. Up to date, data concerning the role of WAT in the pathogenesis of CD is limited with only a few studies on the relationship between WAT and the course of the disease, as well as pro- and anti-inflammatory cytokine profile and general immune system functioning. In this review, we focus on the importance of physiological and pathophysiological WAT functions and secreted adipokines, which seem to have a vital role in the inflammatory and fibrotic processes in CD sufferers.

PCSK9: A novel inflammation modulator in atherosclerosis?

Proprotein convertase subtilisin/kexin 9 (PCSK9) is the ninth member of the secretory serine protease family. It binds to low-density lipoprotein receptor (LDLR) for endocytosis and lysosome degradation in the liver, resulting in an increasing in circulating LDL-cholesterol (LDL-c) level. Since a PCSK9 induced increase in plasma LDL-c contributes to atherosclerosis, PCSK9 inhibition has become a new strategy in preventing and treating atherosclerosis. However, in addition to the effect of PCSK9 on elevating blood LDL-c levels, accumulating evidence shows that PCSK9 plays an important role in inflammation, likely representing another major mechanism for PCSK9 to promote atherosclerosis. In this review, we discuss the association of PCSK9 and inflammation, and highlight the specific effects of PCSK9 on different vascular cellular components involved in the atherosclerotic inflammation. We also discuss the clinical evidence for the association between PCSK9 and inflammation in atherosclerotic cardiovascular disease. A better understanding of the direct association of PCSK9 with atherosclerotic inflammation might help establish a new role for PCSK9 in vascular biology and identify a novel molecular mechanism for PCSK9 therapy.

The effect of a garlic supplement on the pro-inflammatory adipocytokines, resistin and tumor necrosis factor-alpha, and on pain severity, in overweight or obese women with knee osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a prevalent degenerative joint disease, which is associated with chronic and disabling pain. The adipocytokines, resistin and tumor necrosis factor-alpha (TNF-α), might play a role in OA pathogenesis and outcomes.

PURPOSE

The aim of this study was, therefore, to assess the anti-inflammatory and analgesic effects of a garlic supplement on serum resistin and TNF-α concentrations and on pain severity in overweight or obese women with knee OA.

STUDY DESIGN

Randomized, double-blind, placebo-controlled, parallel-design trial.

METHODS

In this study, 80 post-menopausal overweight or obese women (25 ≤ BMI ≤ 40 kg/m², age 50-75 years) with mild to moderate knee OA were enrolled. Patients were randomly divided into two groups to receive twice-daily either garlic tablets (total: 1000 mg) or placebo for 12 weeks. The primary outcome measures were fasting serum concentrations of resistin and TNF-α, and pain severity (assessed using 0-10 point visual analogue scale (VAS)).

RESULTS

At week 12, resistin concentrations were significantly decreased in the garlic group (6.41 ± 2.40 to 5.56 ± 2.16 ng/ml; P = 0.008). Serum TNF-α levels did not change significantly within or between the two groups. Pain scores were significantly reduced in the garlic (6.8 ± 2 to 5.3 ± 2.3; P = 0.002), but not in the placebo (6.7 ± 2.4 to 6.2 ± 2.5; P = 0.674), group. Pain scores were also significantly lower in the garlic, compared with the placebo, group following supplementation (5.3 ± 2.3 vs. 6.2 ± 2.5; P = 0.043).

CONCLUSIONS

The findings suggest that garlic supplementation for 12 weeks might reduce pain severity in overweight or obese women with knee OA, which may, at least in part, be mediated via a reduction in the pro-inflammatory adipocytokine, resistin.

The Effects of Mouse Recombinant Resistin on mRNA Expression of Proinflammatory and Anti-Inflammatory Cytokines and Heat Shock Protein-70 in Experimental Stroke Model

BACKGROUND

Our recent research showed that resistin has a neuroprotective effect against stroke-induced injury through suppressing apoptosis and oxidative stress. However, the molecular mechanism of neuroprotection of resistin is unclear. This work was designed to examine the effect of mouse recombinant resistin on mRNA expression of Tumor necrosis factor-α (TNF-α), Interleukin-1β (IL-1β), Interleukin-10 (IL-10), Transforming growth factor-β1 (TGF- β1), and Heat shock protein-70 (HSP-70) in mouse model of stroke.

MATERIALS AND METHODS

Transient focal cerebral ischemia was induced by the middle cerebral artery occlusion (MCAO) in mice. TNF-α, IL-1β, IL-10, TGF-β1, and HSP-70 mRNA were detected at sham (0 hour), 3 hours, 6 hours, 12 hours, and 24 hours after MCAO using real-time QRT-PCR method. Moreover, animals were treated with resistin at the dose of 400ng/mouse at the commencement of MCAO, and mRNA expression of the cytokines and HSP-70 was measured 24 hours after MCAO.

RESULTS

Tumor necrosis factor-α and IL-1β mRNA expression markedly increased at 12-hour time point and then returned to the basal level at 24 hours after MCAO; but HSP-70 mRNA expression increased at 24-hour time point. Furthermore, resistin (400 ng/mouse) significantly increased TGF-β1 and IL-10 and decreased HSP-70 gene expression at 24 hours after MCAO.

CONCLUSIONS

Our findings revealed that a molecular mechanism of attenuating ischemic damage by resistin administration probably is increased mRNA expression of anti-inflammatory cytokines. However, applying resistin in the clinical settings for the treatment of stroke deserves further researches in the future.

Newborn adipokines and early childhood growth

BACKGROUND

While adipokines can regulate satiety and energy metabolism, whether they are associated with childhood growth is unclear.

OBJECTIVE

To evaluate whether adipokine levels at birth are associated with growth.

METHODS

A total of 2264 singletons and 1144 twins from Upstate KIDS (born 2008-2010) had adiponectin, leptin, resistin and complement factor D measured in newborn blood spots. Parents reported anthropometry from paediatric visits via questionnaires every 4-6 months. Generalized linear mixed effects models were used to estimate growth trajectories through 3 years of age.

RESULTS

Among singletons, resistin and leptin were associated with greater weight-for-age (0.12 z-score units (95%CI: 0.04, 0.20) [p = 0.003] and 0.15 (0.06, 0.24) [p = 0.001], respectively) and BMI z-score (0.11; 0.02, 0.20 [p = 0.02] and 0.18; 0.07, 0.28 [p = 0.002], respectively). After adjusting for birthweight, resistin and a ratio of resistin-to-adiponectin remained associated with weight through 3 years of age and odds of being overweight at 3 years of age in a subgroup of singletons. Among twins, adiponectin was associated with increased weight-for-age and length-for-age z-scores even after adjusting for birthweight (0.18; 0.08, 0.28 [p = 0.0006]; 0.20; 0.07, 0.33 [p = 0.003], respectively).

CONCLUSIONS

Levels of adipokines were associated with early childhood growth in small magnitudes. Resistin may be relevant for further examination in paediatric obesity.

The impact of metabolic reprogramming on dendritic cell function

Dendritic cells (DCs) are antigen-presenting cells with the ability to activate naïve T cells and direct the adaptive cellular immune response toward a specific profile. This is important, as different pathogens demand specific "profiles" of immune responses for their elimination. Such a goal is achieved depending on the maturation/activation status of DCs by the time of antigen presentation to T cells. Notwithstanding this, recent studies have shown that DCs alter their metabolic program to accommodate the functional changes in gene expression and protein synthesis that follow antigen recognition. In this review, we aim to summarize the data in the literature regarding the metabolic pathways involved with DC phenotypes and their functions.

Inflammation, obesity and rheumatic disease: common mechanistic links. A narrative review

Obesity represents a rising global health concern, linked to significant social, psychological and physical burden to the individual affected, people around them and the society as a whole. Obesity has been described as a low-grade inflammatory condition, associated with increased production of pro-inflammatory mediators like tumor necrosis factor alpha or interleukin 6 and altered expression of adipokines. Adipokines, mainly produced by adipose tissue, have mixed pro- and anti-inflammatory properties. Obesity rarely exists on its own; instead, it tends to coexist with (often multiple) other comorbidities, including metabolic, cardiovascular, and rheumatic and musculoskeletal diseases (RMDs). In the case of RMDs, evidence is rapidly accumulating on common mechanistic pathways implicated in the inflammatory states seen between RMDs and obesity. Although there remain unanswered questions on the exact mechanisms of inflammation that link obesity to RMDs, what is becoming increasingly known is the association between obesity and adverse clinical outcomes in RMDs. This narrative review discusses insights into mechanisms of inflammation linking obesity and RMDs and evidence on the impact of obesity on treatment response and important disease outcomes. We highlight the importance of targeting obesity, a common and modifiable comorbidity, as part of the routine care of people with RMDs.

The complex effects of adipokines in the patients with kidney disease

Kidney diseases are categorized as the highest prevalent ones with worldwide noticeable incidence. They cause accelerated cardiovascular diseases and noticeable mortalities. Adipose tissue and its messengers, adipokines, are reported to have the highest relationship with end-stage renal diseases or chronic kidney diseases. Over recent years, with shifting of scientists’ mindset from a simple overview of adipose tissue as a fat store to the complex paradigm of this issue as a multipotential secretory organ, the importance of studies on this tissue has emerged.

When the source of inflammation is hiding in plain sight: Failed kidney transplants, clotted arteriovenous grafts, and central venous catheters

Cardiovascular mortality accounts for most deaths among hemodialysis patients and far exceeds the cardiovascular mortality rate of the general population. One important aspect of cardiovascular risk among dialysis patients is chronic inflammation. Iatrogenic sources of chronic inflammation in the form of failed renal allografts, old clotted arteriovenous grafts, and hemodialysis catheters play important, sometimes, unrecognized roles in this inflammatory state. There is ample observational evidence that these sources of inflammation are associated with hypoalbuminemia, erythropoetin-resistant anemia, and increased markers of chronic inflammation. In dialysis patients with chronic inflammation from potentially modifiable sources, causes should be sought and correction undertaken if possible. Allograft nephrectomy should be offered to patients with a chronic inflammatory state and a failed renal transplant. Unused, clotted AV grafts should be considered a likely source of chronic inflammation as well as infection and should be removed when evidence of infection is present on indium scanning. Catheter rates ought to be kept to a minimum for the many well-recognized reasons for their undesirability as well as for their potential to produce chronic inflammation with all of its ill effects.

Visfatin and resistin in gonadotroph cells: expression, regulation of LH secretion and signalling pathways

Visfatin and resistin appear to interfere with reproduction in the gonads, but their potential action at the hypothalamic-pituitary level is not yet known. The aim of the present study was to investigate the mRNA and protein expression of these adipokines in murine gonadotroph cells and to analyse the effects of different concentrations of recombinant mouse visfatin and resistin (0.01, 0.1, 1 and 10ngmL^-1) on LH secretion and signalling pathways in LβT2 cells and/or in primary female mouse pituitary cells. Both visfatin and resistin mRNA and protein were found in vivo in gonadotroph cells. In contrast with resistin, the primary tissue source of visfatin in the mouse was the skeletal muscle, and not adipose tissue. Visfatin and resistin both decreased LH secretion from LβT2 cells after 24h exposure of cells (P<0.03). These results were confirmed for resistin in primary cell culture (P<0.05). Both visfatin (1ngmL^-1) and resistin (1ngmL^-1) increased AMP-activated protein kinase α phosphorylation in LβT2 cells after 5 or 10min treatment, up to 60min (P<0.04). Extracellular signal-regulated kinase 1/2 phosphorylation was transiently increased only after 5min resistin (1ngmL^-1) treatment (P<0.01). In conclusion, visfatin and resistin are expressed in gonadotroph cells and they may affect mouse female fertility by regulating LH secretion at the level of the pituitary.

Hematopoietic cell-derived RELMα regulates hookworm immunity through effects on macrophages

Resistin-like molecule α (RELMα) is a highly secreted protein in type 2 (Th2) cytokine-induced inflammation including helminth infection and allergy. In infection with Nippostrongylus brasiliensis (Nb), RELMα dampens Th2 inflammatory responses. RELMα is expressed by immune cells, and by epithelial cells (EC); however, the functional impact of immune versus EC-derived RELMα is unknown. We generated bone marrow (BM) chimeras that were RELMα deficient (RELMα^{-/ -} ) in BM or non BM cells and infected them with Nb. Non BM RELMα^-/- chimeras had comparable inflammatory responses and parasite burdens to RELMα^+/+ mice. In contrast, both RELMα^-/- and BM RELMα^-/- mice exhibited increased Nb-induced lung and intestinal inflammation, correlated with elevated Th2 cytokines and Nb killing. CD11c⁺ lung macrophages were the dominant BM-derived source of RELMα and can mediate Nb killing. Therefore, we employed a macrophage-worm co-culture system to investigate whether RELMα regulates macrophage-mediated Nb killing. Compared to RELMα^{+ /+} macrophages, RELMα^-/- macrophages exhibited increased binding to Nb and functionally impaired Nb development. Supplementation with recombinant RELMα partially reversed this phenotype. Gene expression analysis revealed that RELMα decreased cell adhesion and Fc receptor signaling pathways, which are associated with macrophage-mediated helminth killing. Collectively, these studies demonstrate that BM-derived RELMα is necessary and sufficient to dampen Nb immune responses, and identify that one mechanism of action of RELMα is through inhibiting macrophage recruitment and interaction with Nb. Our findings suggest that RELMα acts as an immune brake that provides mutually beneficial effects for the host and parasite by limiting tissue damage and delaying parasite expulsion.

Association of single nucleotide polymorphisms in resistin gene with rheumatoid arthritis in a Chinese population

BACKGROUND

Recent evidences have revealed that resistin is associated with the development of rheumatoid arthritis (RA). The aim of this study was to analyze the association of resistin gene single nucleotide polymorphisms (SNPs) with RA susceptibility.

METHODS

In this study, we finally analyzed three resistin SNPs (rs1862513, rs3745368, and rs3745367) in 278 RA patients and 276 normal controls recruited from Chinese population using TaqMan SNP genotyping assays.

RESULTS

There were no significant differences for the distribution of allele and genotype frequencies of these three SNPs between RA patients and normal controls (all P > .05). The genotype effects of dominant, recessive models were also analyzed, and no significant association was detected (all P > .05). Haplotype analysis suggested that the frequency of haplotype GAA was notably lower in RA patients in comparison with normal controls (OR = 0.317, 95% CI: 0.125-0.807, P = .011).

CONCLUSION

In a ward, our results indicated that resistin gene polymorphisms might affect the genetic predisposition of RA in Chinese population.

The interplay between adipose tissue and the cardiovascular system: is fat always bad?

Obesity is a risk factor for cardiovascular disease (CVD). However, clinical research has revealed a paradoxically protective role for obesity in patients with chronic diseases including CVD, suggesting that the biological 'quality' of adipose tissue (AT) may be more important than overall AT mass or body weight. Importantly, AT is recognised as a dynamic organ secreting a wide range of biologically active adipokines, microRNAs, gaseous messengers, and other metabolites that affect the cardiovascular system in both endocrine and paracrine ways. Despite being able to mediate normal cardiovascular function under physiological conditions, AT undergoes a phenotypic shift characterised by acquisition of pro-oxidant and pro-inflammatory properties in cases of CVD. Crucially, recent evidence suggests that AT depots such as perivascular AT and epicardial AT are able to modify their phenotype in response to local signals of vascular and myocardial origin, respectively. Utilisation of this unique property of certain AT depots to dynamically track cardiovascular biology may reveal novel diagnostic and prognostic tools against CVD. Better understanding of the mechanisms controlling the 'quality' of AT secretome, as well as the communication links between AT and the cardiovascular system, is required for the efficient management of CVD.

The role of infiltrating immune cells in dysfunctional adipose tissue

Adipose tissue (AT) dysfunction, characterized by loss of its homeostatic functions, is a hallmark of non-communicable diseases. It is characterized by chronic low-grade inflammation and is observed in obesity, metabolic disorders such as insulin resistance and diabetes. While classically it has been identified by increased cytokine or chemokine expression, such as increased MCP-1, RANTES, IL-6, interferon (IFN) gamma or TNFα, mechanistically, immune cell infiltration is a prominent feature of the dysfunctional AT. These immune cells include M1 and M2 macrophages, effector and memory T cells, IL-10 producing FoxP3+ T regulatory cells, natural killer and NKT cells and granulocytes. Immune composition varies, depending on the stage and the type of pathology. Infiltrating immune cells not only produce cytokines but also metalloproteinases, reactive oxygen species, and chemokines that participate in tissue remodelling, cell signalling, and regulation of immunity. The presence of inflammatory cells in AT affects adjacent tissues and organs. In blood vessels, perivascular AT inflammation leads to vascular remodelling, superoxide production, endothelial dysfunction with loss of nitric oxide (NO) bioavailability, contributing to vascular disease, atherosclerosis, and plaque instability. Dysfunctional AT also releases adipokines such as leptin, resistin, and visfatin that promote metabolic dysfunction, alter systemic homeostasis, sympathetic outflow, glucose handling, and insulin sensitivity. Anti-inflammatory and protective adiponectin is reduced. AT may also serve as an important reservoir and possible site of activation in autoimmune-mediated and inflammatory diseases. Thus, reciprocal regulation between immune cell infiltration and AT dysfunction is a promising future therapeutic target.

Hyperadiponectinemia During Infliximab Induction Therapy in Pediatric Crohn Disease

OBJECTIVES

The inflammatory process in Crohn disease (CD) involves the visceral fat, characterized by adipocyte hyperplasia and altered adipose tissue and serum concentrations of tumor necrosis factor (TNF), leptin, adiponectin and resistin. We investigated the effect of anti-TNF therapy with infliximab (IFX) on serum adipokine levels in pediatric CD.

METHODS

Serum concentrations of resistin (ng/mL), leptin (ng/mL), and total adiponectin (μg/mL) were assessed by enzyme-linked immunosorbent assays (ELISA) in 18 pediatric CD patients (mean age 15.0 ± 1.5 years) before first, second, and fourth IFX infusion (weeks 0, 2, and 14) and compared with baseline values from sex- and BMI-matched healthy controls (HC, mean age 13.4 ± 1.6 years).

RESULTS

At baseline, CD patients (mean age 15.0 ± 1.5 years, 10 of 18 boys) compared with HC (13.4 ± 1.6 years, 7 of 15 boys) had higher resistin levels (median 14.7 ng/mL, range 5.1-50.5 vs 7.3 ng/mL, 0.5-14.5); P = 0.0002). At weeks 2 and 14, resistin decreased to 6.9 ng/mL (2.9-16.8) (P < 0.0001) and 9.2 ng/mL (4.1-20.6; P = 0.0011), respectively. Leptin and adiponectin were comparable between patients and HC at baseline. Leptin increased in girls from 9.5 ng/mL (4.0-30.1) to 16.0 ng/mL (7.9-35.2; P = 0.0156) and 17.2 ng/mL (10.8- 26.8; P = 0.1953) at weeks 0, 2, and 14 respectively; with a trend in boys from 2 (0.6-12.9) to 2.8 (1.7-8.6; P = 0.0840) and 3.3 (1.3-4.6; P = 0.1309). Adiponectin peaked initially from 7.8 μg/mL (4.6-11.9) at week 0 to 9.2 μg/mL (4.1-20.7; P = 0.0005) at week 2 and thereafter fell to 6.5 μg/mL (3.0-12.7; P = 0.0182) at week 14.

CONCLUSIONS

TNF blockade is associated with changes in circulating adipokines. The marked early increase of the potent anti-inflammatory adiponectin may contribute to the rapid response to IFX in CD.

The role of adipokines in skeletal muscle inflammation and insulin sensitivity

Background

There is currently an unmet clinical need to develop better pharmacological treatments to improve glucose handling in Type II Diabetes patients with obesity. To this end, determining the effect of obesity-associated adipokines on skeletal muscle insulin sensitivity has emerged as an important area of drug discovery research. This review draws together the data on the functional role of adipokines on skeletal muscle insulin signalling, highlights several understudied novel adipokines and provides a perspective on the direction of future research.

Main body

The adipokines leptin, resistin, visfatin and adiponectin have all been shown to affect skeletal muscle insulin sensitivity by impacting on the activity of components within insulin signalling pathways, affecting GLUT4 translocation and modulating insulin-mediated skeletal muscle glucose uptake. Furthermore, proteomic analysis of the adipose tissue secretome has recently identified several novel adipokines including vaspin, chemerin and pref-1 that are associated with obesity and insulin resistance in humans and functionally impact on insulin signalling pathways. However, predominantly, these functional findings are the result of studies in rodents, with in vitro studies utilising either rat L6 or murine C2C12 myoblasts and/or myotubes. Despite the methodology to isolate and culture human myoblasts and to differentiate them into myotubes being established, the use of human muscle in vitro models for the functional validation of adipokines on skeletal muscle insulin sensitivity is limited.

Conclusion

Understanding the mechanism of action and function of adipokines in mediating insulin sensitivity in skeletal muscle may lead to the development of novel therapeutics for patients with type 2 diabetes. However, to date, studies conducted in human skeletal muscle cells and tissues are limited. Such human in vitro studies should be prioritised in order to reduce the risk of candidate drugs failing in the clinic due to the assumption that rodent skeletal muscle target validation studies will to translate to human.

Effect of Low-Selenium/High-Fat Diet on Pig Peripheral Blood Lymphocytes: Perspectives from Selenoproteins, Heat Shock Proteins, and Cytokines

The aim of the present study was to clarify the effect of low selenium (Se)/high fat on the mRNA expression of selenoproteins, heat shock proteins (HSPs) and cytokines in pig peripheral blood lymphocytes. Forty crossbred boar piglets with healthy lean body weights of 10 kg were randomly divided into four treatment groups (group C, group L-Se, group H-fat, and group L-Se-H-fat) (n = 10/group) and fed with the corresponding diet for 16 weeks. The pig peripheral blood lymphocytes were extracted, and the mRNA expression of selenoproteins, HSPs, and cytokines was measured. Most mRNA levels for selenoproteins decreased in group L-Se, group H-fat, and group L-Se-H-fat, except Gpx1, Gpx2, Selt, and Selm, which were elevated in group H-fat. At the same time, low-Se/high-fat diet increased the expression of HSPs (HSP40, HSP60, HSP70, and HSP90) and inflammatory cytokines (IL-1α, IL-1β, IL-6, IL-8, IL-9, iNOS, COX-2, NF-κB, and TNF-α) in group L-Se, group H-fat, and group L-Se-H-fat, and genes in group L-Se-H-fat showed greater increases. Also, low-Se/high-fat diet inhibits the expression of TGF-β1 and IFN-γ. In summary, a low-Se/high-fat diet can cause relevant selenoprotein expression changes and promote the expression of pro-inflammatory factors and HSPs, and low Se enhances the expression of HSPs and inflammation factors induced by high fat. This information is helpful for understanding the effects of low-Se and high-fat diet on pig peripheral blood lymphocytes.

Activation of the porcine alveolar macrophages via toll-like receptor 4/NF-κB mediated pathway provides a mechanism of resistin leading to inflammation

Resistin, a previously discovered cysteine-rich adipokine known to regulate glucose metabolism, has been emerged as a mediator in inflammation and immunity. Its level was supposed to be related to the expression of indicators, such as interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) in inflammation. Toll-like receptor 4 (TLR4) was reported to be a receptor for resistin in cells, like leukocytes and peripheral blood mononuclear cells (PBMC). However, the pro-inflammatory role of resistin and its intracellular mechanisms in alveolar macrophages have not been thoroughly validated. Here we found that the pro-inflammatory cytokine expression in porcine alveolar macrophages (PAMs) was positively correlated with resistin. Our results also showed that resistin induced the expression of TLR4, intracellular molecules myeloid differentiation primary response protein 88 (MyD88), TRIF-related adaptor molecule (TRAM) and nuclear factor κB (NF-κB) in PAMs. In contrast, inhibition of TLR4, MyD88, TRAM and NF-κB abrogated the pro-inflammatory effect of resistin on PAMs. Additionally, the associations among TLR4, MyD88/TRAM and NF-κB were investigated by introducing TLR4-siRNA, MyD88-siRNA and TRAM-siRNA respectively into PAMs prior to the treatment with resistin. Taken together, our findings demonstrated that resistin promoted the production of pro-inflammatory cytokine in PAMs via TLR4/NF-κB-mediated pathway (TLR4/MyD88/TRAM/NF-κB).

Chemerin, Resistin, and Adiponectin in Patients with Connective Tissue Diseases

Background

The exact role of cytokines in inflammation and metabolic disorders in case of connective tissue diseases (CTDs) is under discussion.

Methods

In this study, we intended to find the relationship between the selected cytokines in inflammatory and metabolic disorders in patients with CTDs (n=55) and compared the results with those of control group subjects (n=25) matched by age and body mass. We estimated their nutritional status by the bioimpedance method. The levels of basic biochemical parameters and the levels of adiponectin, resistin, and chemerin were also estimated. Multiple regressions and area under the curve in receiver operating characteristic (AUC-ROC) curve were used to find the associations of aforementioned parameters.

Results

Patients with CTDs exhibited higher levels of chemerin than that of control group subjects. We found an inverse relationship between chemerin, RBC count, and hemoglobin levels. The concentration of adiponectin inversely correlated with the levels of platelets and concentrations of glucose and triglycerides as well as the erythrocyte sedimentation rate, whereas the concentration of resistin was positively correlated with WBC count, C-reactive protein (CRP), and the amount of used oral glucocorticosteroids. The mean ± standard deviation for the AUC-ROC curve in case of chemerin was the highest (AUC-ROC=0.714, p=0.0005) than that of both resistin and adiponectin.

Conclusions

Chemerin and resistin levels are related to the inflammatory state in patients with CTDs, whereas adiponectin levels seem to be correlated with a protective effect. Chemerin can be considered as a marker differentiating a proinflammatory state present in CTDs.

Association of RETN and CAP1 SNPs, Expression and Serum Resistin Levels with Breast Cancer in Mexican Women

BACKGROUND

Breast cancer is the most common cancer in women worldwide. Approximately 70% of female breast cancer patients have a body mass index (BMI) >25. In obesity, adipose tissue secretes additional resistin, which prompts a proinflammatory effect through its action on adenylate cyclase-associated protein 1 (CAP1). Several studies have associated the RETN gene single nucleotide polymorphism (SNP) rs1862513 (-420C<G) with serum resistin levels and breast cancer. The CAP1 gene SNP rs35749351 (missense, Arg294His), located in the extracellular domain, has not previously been studied in cancer. These two SNPs, the mRNA expression levels of the two alleles for each of the cognate genes, and the serum resistin levels were compared between patients and controls to determine their association with breast cancer in Mexican women in this study.

MATERIALS AND METHODS

This study included 308 controls and 100 female patients with breast cancer. SNPs were detected by PCR-RFLP from DNA isolated from peripheral blood. Gene expression was performed with hydrolysis probes in tumor tissue. Resistin levels were quantified from serum samples by ELISA.

RESULTS

The RETN rs1862513CG/GG and CAP1 rs35749351GA/AA genotypes were associated with 1.61 and 2.193-fold increased risks of breast cancer, respectively, compared with the CC and GG genotypes. Similarly, carriers of the G allele of rs1862513 and the A allele of rs35749351, had 1.51 and 2.217-fold increased risks of breast cancer compared with the C and G alleles, respectively. The rs1862513GG/rs35749351AA genotype combination increased breast cancer risk by twofold. Serum resistin levels in postmenopausal breast cancer women were higher compared with postmenopausal controls. Tissue CAP1 expression showed differences with regard to molecular subtypes and metastases.

CONCLUSION

The RETN and CAP1 polymorphisms and gene expression may be potential biomarkers for breast cancer risk.

Inflammatory biomarkers responses after acute whole body vibration in fibromyalgia

The aims of this study were 1) to characterize the intensity of the vibration stimulation in women diagnosed with fibromyalgia (FM) compared to a control group of healthy women (HW) matched by age and anthropometric parameters, and 2) to investigate the effect of a single session of whole body vibration (WBV) on inflammatory responses. Levels of adipokines, soluble tumor necrosis factor receptors (sTNFr1, sTNFr2), and brain-derived neurotrophic factor (BDNF) were determined by enzyme-linked immunosorbent assay. Oxygen consumption (VO2) was estimated by a portable gas analysis system, heart rate (HR) was measured using a HR monitor, and perceived exertion (RPE) was evaluated using the Borg scale of perceived exertion. Acutely mild WBV increased VO2 and HR similarly in both groups. There was an interaction (disease vs vibration) in RPE (P=0.0078), showing a higher RPE in FM compared to HW at rest, which further increased in FM after acute WBV, whereas it remained unchanged in HW. In addition, there was an interaction (disease vs vibration) in plasma levels of adiponectin (P=0.0001), sTNFR1 (P=0.000001), sTNFR2 (P=0.0052), leptin (P=0.0007), resistin (P=0.0166), and BDNF (P=0.0179). In conclusion, a single acute session of mild and short WBV can improve the inflammatory status in patients with FM, reaching values close to those of matched HW at their basal status. The neuroendocrine mechanism seems to be an exercise-induced modulation towards greater adaptation to stress response in these patients.

Association of circulating resistin, leptin, adiponectin and visfatin levels with Behçet disease: a meta-analysis

BACKGROUND

Behçet disease (BD) is a chronic inflammatory disease. Adipokines are synthesized in adipose tissue, and have been reported to play important roles in the pathogenesis of autoimmune and inflammatory diseases, including BD.

AIM

To evaluate the relationship between circulating blood adipokine levels and BD.

METHODS

We conducted a meta-analysis of papers reporting on serum/plasma resistin, leptin, adiponectin and visfatin levels in patients with BD and in healthy controls (HCs). We identified 82 relevant studies using electronic and manual search methods, and selected 16 studies for full-text review based on the title and abstract. Two of these were later excluded (one was a review, one had no data), leaving 14 articles that met the inclusion criteria for this meta-analysis.

RESULTS

The 14 included studies assessed 637 patients with BD and 520 HCs. Compared with the HCs, the BD group had significantly higher levels of leptin [standardized mean difference (SMD) = 0.68, 95% CI 0.15-1.21, P = 0.01]. Levels of resistin (SMD = 0.51, 95% CI 0.92-0.918, P = 0.02) and adiponectin (SMD = 0.31, 95% CI 0.06-0.56, P = 0.02) were significantly higher in the BD group after adjustment for age, sex and body mass index (BMI), but not without such adjustment (resistin: (SMD = 0.38, 95% CI -0.18 to 0.93, P = 0.19; adiponectin: SMD = -0.59, 95% CI -2.23 to 1.06, P = 0.48). A significantly lower visfatin level was found in the BD group with adjustment (SMD = -1.70, 95% CI -2.14 to -1.25, P < 0.001) but not without adjustment (SMD = 0.31, 95% CI -0.21 to 0.82, P = 0.24).

CONCLUSIONS

Our meta-analysis revealed significantly higher circulating resistin, leptin and adiponectin levels and lower visfatin levels in patients with BD than in HCs, indicating that adipokines probably play an important role in BD pathogenesis.

The Effect of SH2B1 Variants on Expression of Leptin- and Insulin-Induced Pathways in Murine Hypothalamus

OBJECTIVE

We aimed to determine the effect of human SH2B1 variants on leptin and insulin signaling, major regulators of energy homeostasis, on the RNA level.

METHODS

We analyzed the expression of infrequent alleles of seven SH2B1 variants (Arg67Cys, Lys150Arg, Thr175Ala, Thr343Met, Thr484Ala, Ser616Pro and Pro689Leu) in response to insulin or leptin cell stimulation. Two of these were identified in own mutation screens, the others were predicted to be deleterious or to serve as controls. The variants were analyzed in a homologous system of mouse hypothalamic cells. Changes in expression of downstream genes were measured. Student’s t-test for independent samples was applied and effect sizes using Cohen’s d were calculated.

RESULTS

In 34 of 54 analyzed genes involved in leptin (JAK/STAT or AKT) signaling, variants nominally changed expression. The expression of three genes was considerably increased (p values ≤ 0.001: Gbp2b (67Cys; d = 25.11), Irf9 (689Leu; d = 44.65) and Isg15 (150Arg; d = 20.35)). Of 32 analyzed genes in the insulin signaling pathway, the expression of 10 genes nominally changed (p ≤ 0.05), three resulted in p values ≤ 0.01 ( Cap1 (150Arg; d = 7.48), Mapk1 (343Met; d = –6.80) and Sorbs1 (689Leu; d = 7.82)).

CONCLUSION

The increased expression of genes in leptin (JAK/STAT or AKT) signaling implies that the main mode of action for human SH2B1 mutations might affect leptin signaling rather than insulin signaling.