Adiponectin, an Unlocking Adipocytokine

Exploring Adiponectin in Autosomal Dominant Kidney Disease: Insight and Implications

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a common monogenic disorder characterized by renal cysts and progressive renal failure. In kidney diseases, adipose tissue undergoes functional changes that have been associated with increased inflammation and insulin resistance mediated by release of adipokines. Adiponectin is involved in various cellular processes, such as energy and inflammatory and oxidative processes. However, it remains to be determined whether adiponectin is involved in the concomitant metabolic dysfunctions present in PKD. In this scenario, we aimed to analyze: (a) PPARγ, ADIPOQ, ADIPOR1 and ADIPOR2 gene variations in 92 ADPKD patients through PCR-Sanger sequencing; and (b) adiponectin levels and its oligomerization state by ELISA and Western Blot. Our results indicated that: (a) 14 patients carried the PPARγ SNP, 29 patients carried the ADIPOQ SNP rs1501299, and 25 patients carried the analyzed ADIPOR1 SNPs. Finally, 82 patients carried ADIPOR2 SNPs; and (b) Adiponectin is statistically lower in ADPKD patients compared to controls, and further statistically lower in ESRD than in non-ESRD patients. An inverse relationship between adiponectin and albumin and between adiponectin and creatinine and a direct relationship between adiponectin and eGFR were found. Interestingly, significantly lower levels of adiponectin were found in patients bearing the ADIPOQ rs1501299 SNP and associated with low levels of eGFR. In conclusion, adiponectin levels and the presence of ADIPOQ rs1501299 genotype are significantly associated with a worse ADPKD phenotype, indicating that both could potentially provide important insights into the disease. Further studies are warranted to understand the pathophysiological role of adiponectin in ADPKD patients.

Patients with systemic lupus erythematosus who are underweight have distinct disease characteristics

OBJECTIVE

This study aimed to detail the disease characteristics of systemic lupus erythematosus (SLE) in individuals who are underweight and assess whether underweight status is associated with SLE disease activity.

METHODS

This was a retrospective cohort study involving 218 patients newly diagnosed with SLE. Patients were categorized as underweight (body mass index [BMI] <18.5 kg/m2) or not underweight (BMI ≥18.5 kg/m2). We reviewed disease characteristics including the SLE Disease Activity Index 2000 (SLEDAI-2K) at diagnosis. High disease activity was defined as SLEDAI-2K ≥10. Disease characteristics were compared between those who were underweight and not underweight. We used multivariable logistic regression analysis to determine whether underweight status is associated with high disease activity.

RESULTS

Out of the 218 patients, 35 (16.1%) were underweight and 183 (83.9%) were not. Underweight patients had less renal involvement (5.7% vs 20.2%, p = .040), lower C-reactive protein levels (1.0 [0.3-2.3] mg/L vs 1.2 [0.8-5.0] mg/L, p = .028), and lower SLEDAI-2K scores (6.7 ± 4.6 vs 9.1 ± 5.7, p = .009), and were less likely to be at high disease activity status (22.9% vs 42.6%, p = .028), compared with those who were not underweight. Following adjustment for multiple covariates, being underweight was inversely associated with high disease activity status (adjusted odds ratio = 0.38, 95% confidence interval = 0.16 to 0.92, p = .031).

CONCLUSION

Patients with SLE who were underweight showed less renal involvement and lower SLEDAI-2K scores compared with those who were not underweight. Moreover, those with SLE who were underweight had a 60% lower risk of exhibiting high disease activity.

Physical exercise for a healthy pregnancy: the role of placentokines and exerkines

Complications such as diabetes and preeclampsia can occur during pregnancy. Moderate-intensity exercise can prevent such complications by releasing placentokines and exerkines, such as apelin, adiponectin, leptin, irisin, and chemerin. Exercise and apelin increase thermogenesis and glucose uptake in pregnancy by activating AMPK, PI3K, PGC-1α, AKT1, UCP3, and sarcolipin. Exercise increases apelin levels to reduce preeclampsia symptoms by increasing eNOS, NO, placental growth factor (PlGF), and VEGF and decreasing levels of fms-like tyrosine kinase 1 (sFlt-1), soluble endoglin (sEng), and oxidative stress. A negative relationship has been reported between plasma leptin and VO2peak/kg and VO2peak in women with gestational diabetes. In active women, decreases in leptin levels reduce the risk of preeclampsia by ~ 40%. Higher adiponectin levels are associated with greater physical activity and lead to increased insulin sensitivity. Increased adiponectin levels in preeclampsia and exercise counteract inflammatory and atherogenic activities while also having vascular protective effects. Exercise increases irisin levels that correlate negatively with fasting glucose, insulin concentration, and glycosylated hemoglobin levels. Irisin augments mRNA expression levels of UCP1 and cell death-inducing DNA fragmentation factor-like effector A (cidea) to cause browning of adipose tissue, increased thermogenesis, and increased energy consumption. Irisin concentrations in mothers with preeclampsia in the third trimester negatively correlate with systolic and diastolic blood pressure. Expression levels of chemerin, IL-6, and TNF-α are increased in gestational diabetes, and the increases in chemerin in late pregnancy positively correlate with the ratio of sFlt-1 to PlGF as a marker of preeclampsia. The effects of physical exercise on placentokines and exerkines in women at various stages of pregnancy remain poorly understood.

Adipokines in obesity and metabolic-related-diseases

The discovery of leptin in the 1990s led to a reconsideration of adipose tissue (AT) as not only a fatty acid storage organ, but also a proper endocrine tissue. AT is indeed capable of secreting bioactive molecules called adipokines for white AT or batokines for brown/beige AT, which allow communication with numerous organs, especially brain, heart, liver, pancreas, and/or the vascular system. Adipokines exert pro or anti-inflammatory activities. An equilibrated balance between these two sets ensures homeostasis of numerous tissues and organs. During the development of obesity, AT remodelling leads to an alteration of its endocrine activity, with increased secretion of pro-inflammatory adipokines relative to the anti-inflammatory ones, as shown in the graphical abstract. Pro-inflammatory adipokines take part in the initiation of local and systemic inflammation during obesity and contribute to comorbidities associated to obesity, as detailed in the present review.

Hepatic transcript profiling in beef cattle: Effects of rumen-protected niacin supplementation

The objective of our study was to assess the effect of rumen-protected niacin supplementation on the transcriptome of liver tissue in growing Angus × Simmental steers and heifers through RNA-seq analysis. Consequently, we wanted to assess the known role of niacin in the physiological processes of vasodilation, detoxification, and immune function in beef hepatic tissue. Normal weaned calves (~8 months old) were provided either a control diet or a diet supplemented with rumen-protected niacin (6 g/hd/d) for a 30-day period, followed by a liver biopsy. We observed a significant list of changes at the transcriptome level due to rumen-protected niacin supplementation. Several metabolic pathways revealed potential positive effects to the animal's liver metabolism due to administration of rumen-protected niacin; for example, a decrease in lipolysis, apoptosis, inflammatory responses, atherosclerosis, oxidative stress, fibrosis, and vasodilation-related pathways. Therefore, results from our study showed that the liver transcriptional machinery switched several metabolic pathways to a condition that could potentially benefit the health status of animals supplemented with rumen-protected niacin. In conclusion, based on the results of our study, we can suggest the utilization of rumen-protected niacin supplementation as a nutritional strategy could improve the health status of growing beef cattle in different beef production stages, such as backgrounding operations or new arrivals to a feedlot.

Correlation between adiponectin level and obesity as a risk factor for allergy disease

Much research has focused on the connection between two inflammatory conditions, allergic reactions and obesity which has led to a focus on adiponectin, hormone with anti-inflammatory properties secreted by adipose tissue. The aim of this study was to determine the association of adiponectin with obesity, as a risk factor for the development of allergic condition in order to rationalize approach to its treatment. Research methods for inflammatory markers and biochemical parameters involve immunoassay technique. Statistical analysis was performed with Student’s t-test, Wilcoxon T-test and coefficient of correlation. The study included apparently healthy subjects and patients with allergy conditions with confirmed presence of specific IgE, classified into 2 groups according to their body mass index (BMI). The obtained data showed negative correlation (cor = – 0.6), between adiponectin levels and BMI values. Thus, decreased level of adiponectin is associated with increased BMI. The mean values of adiponectin in the studied population, with high statistical differen­ces between the groups (19.1 ± 1.5; 17.7 ± 0.9), (18.8± 1.1; 16.6 ± 1.0) demonstrated the relationship between low adiponectin level and development of obesity, and what, in turn, increasd risk of developing allergic conditions. The assumption was made that adiponectin may be used as a sensitive biochemical marker for early diagnostics of allergic reactions. Keywords: adiponectin, allergy reactions, obesity, specific IgE

Epicardial fat and atrial fibrillation: the perils of atrial failure

Obesity is a heterogeneous condition, characterized by different phenotypes and for which the classical assessment with body mass index may underestimate the real impact on cardiovascular (CV) disease burden. An epidemiological link between obesity and atrial fibrillation (AF) has been clearly demonstrated and becomes even more tight when ectopic (i.e. epicardial) fat deposition is considered. Due to anatomical and functional features, a tight paracrine cross-talk exists between epicardial adipose tissue (EAT) and myocardium, including the left atrium (LA). Alongside-and even without-mechanical atrial stretch, the dysfunctional EAT may determine a pro-inflammatory environment in the surrounding myocardial tissue. This evidence has provided a new intriguing pathophysiological link with AF, which in turn is no longer considered a single entity but rather the final stage of atrial remodelling. This maladaptive process would indeed include structural, electric, and autonomic derangement that ultimately leads to overt disease. Here, we update how dysfunctional EAT would orchestrate LA remodelling. Maladaptive changes sustained by dysfunctional EAT are driven by a pro-inflammatory and pro-fibrotic secretome that alters the sinoatrial microenvironment. Structural (e.g. fibro-fatty infiltration) and cellular (e.g. mitochondrial uncoupling, sarcoplasmic reticulum fragmentation, and cellular protein quantity/localization) changes then determine an electrophysiological remodelling that also involves the autonomic nervous system. Finally, we summarize how EAT dysfunction may fit with the standard guidelines for AF. Lastly, we focus on the potential benefit of weight loss and different classes of CV drugs on EAT dysfunction, LA remodelling, and ultimately AF onset and recurrence.

Adiponectin Can Be an Early Predictable Marker for Type 2 Diabetes Mellitus and Nephropathy

Background

Several studies have examined serum adiponectin concentrations in prediabetes, newly diagnosed type 2 diabetes mellitus (T2DM), and other types of diabetes associated with the risk of T2DM and diabetic nephropathy (DN); however, the results to date are inconclusive. An aim of the current study is to determine whether adiponectin is a useful marker for the earlier development of T2DM and DN.

Methodology

This cross-sectional study included 400 subjects. Among the subjects, 100 were prediabetes subjects, 200 were T2DM patients, and the remaining 100 were healthy controls. The biochemical and clinical parameters of all patients were analyzed and the data were recorded.

Results

The mean levels of adiponectin were significantly lower in prediabetic subjects than in healthy controls (3.22 ± 0.98, 5.36 ± 2.24, p = 0.0001**). Furthermore, the levels of adiponectin were significantly higher in both the groups of T2DM patients when compared to healthy controls (19.85 ± 3.31, 11.83 ± 3.01, and 5.36 ± 2.24, p = 0.0001**). In both diabetic groups, adiponectin was positively correlated with body mass index, glycated hemoglobin, insulin, homeostasis model assessment of insulin resistance, and microalbuminuria, while negatively correlated with estimated glomerular filtration rate. Interestingly, adiponectin had a reversed correlation in the prediabetic group.

Conclusion

Based on the results, the present study suggests that significantly decreased levels of serum adiponectin in prediabetic subjects might be used as a variable marker for T2DM. Moreover, adiponectin may useful for detecting the early onset of nephropathy, compared to microalbumin, as its concentration was significantly elevated in patients who were newly diagnosed with T2DM without nephropathy. 

The Role of Perivascular Adipose Tissue-Derived Hydrogen Sulfide in the Control of Vascular Homeostasis

Significance: Emerging evidence suggests that perivascular adipose tissue (PVAT) has a relevant role in the control of vascular tone in physiology and pathology. Healthy PVAT has anticontractile, anti-inflammatory, and antioxidative actions. Accumulating data from both human and experimental animal models indicate that PVAT dysfunction is conceivably coupled to cardiovascular diseases, and it is associated with vascular inflammation, oxidative stress, and arterial remodeling. Therefore, "healthy" PVAT may constitute a novel therapeutic target for the prevention and treatment of cardiovascular diseases. Recent Advances: Hydrogen sulfide (H₂S) has been recognized as a vascular anti-contractile factor released from PVAT. The enzymes deputed to H₂S biosynthesis are variously expressed in PVAT and strictly dependent on the vascular bed and species. Metabolic and cardiovascular diseases can alter the morphological and secretory characteristics of PVAT, influencing also the H₂S signaling. Here, we discuss the role of PVAT-derived H₂S in healthy conditions and its relevance in alterations occurring in vascular disorders. Critical Issues: We discuss how a better understanding may help in the prevention of vascular dysfunction related to alteration in PVAT-released H₂S as well as the importance of the interplay between PVAT and H₂S. Future Directions: We propose future directions to evaluate the contribution of each enzyme involved in H₂S biosynthesis and their alteration/switch occurring in vascular disorders and the remaining challenges in investigating the role of H₂S. Antioxid. Redox Signal. 37, 84-97.

Adiponectin Promotes VEGF Expression in Rheumatoid Arthritis Synovial Fibroblasts and Induces Endothelial Progenitor Cell Angiogenesis by Inhibiting miR-106a-5p

Rheumatoid arthritis (RA) is an erosive polyarthritis that can lead to severe joint destruction and painful disability if left untreated. Angiogenesis, a critical pathogenic mechanism in RA, attracts inflammatory leukocytes into the synovium, which promotes production of proinflammatory cytokines and destructive proteases. Adipokines, inflammatory mediators secreted by adipose tissue, also contribute to the pathophysiology of RA. The most abundant serum adipokine is adiponectin, which demonstrates proinflammatory effects in RA, although the mechanisms linking adiponectin and angiogenic manifestations of RA are not well understood. Our investigations with the human MH7A synovial cell line have revealed that adiponectin dose- and time-dependently increases vascular endothelial growth factor (VEGF) expression, stimulating endothelial progenitor cell (EPC) tube formation and migration. These adiponectin-induced angiogenic activities were facilitated by MEK/ERK signaling. In vivo experiments confirmed adiponectin-induced downregulation of microRNA-106a-5p (miR-106a-5p). Inhibiting adiponectin reduced joint swelling, bone destruction, and angiogenic marker expression in collagen-induced arthritis (CIA) mice. Our evidence suggests that targeting adiponectin has therapeutic potential for patients with RA. Clinical investigations are needed.

Distribution of serum adiponectin isoforms in pediatric patients with steroid-sensitive nephrotic syndrome

BACKGROUND

Serum adiponectin circulates in three multimeric isoforms: high-molecular-weight (HMW), middle-molecular-weight (MMW), and low-molecular-weight (LMW) isoforms. Potential change in the circulating adiponectin levels in patients with nephrotic syndrome (NS) remain unknown. This study aimed to assess the levels of total adiponectin and the distribution of its isoforms in pediatric patients with NS.

METHODS

We sequentially measured total adiponectin and each adiponectin isoform levels at the onset of NS, initial remission, and during the remission period of the disease in 31 NS patients. We also calculated the ratios of HMW (%HMW), MMW (%MMW), and LMW (%LMW) to total adiponectin incuding 51 control subjects.

RESULTS

The median of total serum adiponectin levels in patients were 36.7, 36.7, and 20.2 μg/mL at the onset, at initial remission, and during the remission period of NS, respectively. These values were significantly higher than those in control subjects. The median values of %HMW, %MMW, and %LMW values were 56.9/27.0/14.1 at the onset, 62.0/21.8/13.4 at the initial remission, and 58.1/21.7/17.5 at during the remission period of NS, respectively. Compared with control subjects, %HMW at initial remission and %MMW at the onset were high, and the %LMW values at the onset and at initial remission were low.

CONCLUSIONS

In patients with NS, total serum adiponectin levels increase at the onset of the disease, and the ratio of adiponectin isoforms changes during the course of the disease. Further studies are needed to delineate the mechanisms between proteinuria and adiponectin isoforms change.

Chronic hypoxaemia and gender status modulate adiponectin plasmatic level and its multimer proportion in severe COPD patients: new endotypic presentation?

BACKGROUND

Disease progression in COPD patient is associated to lung function decline, leading to a higher risk of hypoxaemia and associated comorbidities, notably cardiovascular diseases (CVD). Adiponectin (Ad) is an adipokine with cardio-protective properties. In COPD patients, conflicting results were previously reported regarding Ad plasmatic (Adpl) level, probably because COPD is a heterogeneous disease with multifactorial influence. Among these factors, gender and hypoxaemia could interact in a variety of ways with Ad pathway. Therefore, we postulated that these components could influence Adpl level and its multimers in COPD patients and contribute to the appearance of a distinct endotype associated to an altered CVD risk.

METHODS

One hundred COPD patients were recruited: 61 were men and 39 were women. Patients who were not severely hypoxemic were allocated to non-hypoxemic group which included 46 patients: 27 men and 19 women. Hypoxemic group included 54 patients: 34 men and 20 women. For all patients, Adpl level and proportion of its different forms were measured. Differences between groups were evaluated by Rank-Sum tests. The relationship between these measures and BMI, blood gas analysis (PaO2, PaCO2), or lung function (FEV1, FEV1/FVC, TLCO, TLC, RV) were evaluated by Pearson correlation analysis.

RESULTS

Despite similar age, BMI and obstruction severity, women had a higher TLC and RV (median: TLC = 105%; RV = 166%) than men (median: TLC = 87%; RV = 132%). Adpl level was higher in women (median = 11,152 ng/ml) than in men (median = 10,239 ng/ml) and was negatively associated with hyperinflation (R = - 0,43) and hypercapnia (R = - 0,42). The proportion of the most active forms of Ad (HMW) was increased in hypoxemic women (median = 10%) compared with non-hypoxemic women (median = 8%) but was not modulated in men.

CONCLUSION

COPD pathophysiology seemed to be different in hypoxemic women and was associated to Ad modulations. Hyperinflation and air-trapping in association with hypercapnia and hypoxaemia, could contribute to a modulation of Adpl level and of its HMW forms. These results suggest the development of a distinct endotypic presentation, based on gender.

Autoantibody Production in Obesity: Is There Evidence for a Link Between Obesity and Autoimmunity?

PURPOSE OF REVIEW

During the last decades, obesity and autoimmune disorders have shown a parallel significant rise in industrialized countries. This review aims at providing a comprehensive update of the relationship between the adipose tissue in obesity and autoimmune disorders, highlighting the underlying mechanisms with a particular emphasis on adipokines and pro-inflammatory cytokines, the impaired B cell activity, and the production of natural and pathogenic autoantibody repertoire in the context of obesity.

RECENT FINDINGS

Obesity is related to a higher risk of rheumatoid arthritis, psoriasis and psoriatic arthritis, multiple sclerosis, and Hashimoto's thyroiditis, while it may promote inflammatory bowel disorders and type 1 diabetes mellitus. Interestingly, subjects with obesity present more severe forms of these autoimmune disorders as well as decreased therapeutic response. Both obesity and autoimmune disorders present elevated levels of leptin, resistin, and visfatin. Autoantibody production, a hallmark of autoimmune disorders, has been demonstrated in obese animal models and human subjects. Obesity results in deficiencies of the human self-tolerance mechanisms by promoting pro-inflammatory processes, reducing Bregs as well as Tregs, and the latter resulting in increased Th17 and Th1 cells, creating the perfect milieu for the development of autoimmune disorders. More mechanistic, animal, and clinical studies are required to delineate the exact mechanisms underlying auto-reactivity in obesity as well as the adipose-immune crosstalk for potential successful therapeutic strategies.

Association Between Adiponectin and Clinical Manifestations in Rheumatoid Arthritis

Adiponectin (APN) belongs to adipokines. Previous studies showed contradictory results that have both proinflammatory and anti-inflammatory effects in rheumatoid arthritis (RA). We set out to detect the levels of APN and the correlations between APN and the clinical manifestations in RA patients. Sera of 60 newly diagnosed patients with RA and 29 age- and gender-matched healthy subjects were collected. Clinical parameters, including C-reactive protein (CRP), erythrocyte sedimentation rate, rheumatoid factor (RF), antibodies to cyclic citrullinated peptide, disease activity score 28, and bone erosion conditions, were collected. The serum levels of total APN and high-molecular-weight APN (HMW-APN) were detected by enzyme-linked immunosorbent assay. As a result, total APN and HMW-APN levels were all lower in patients with RA compared with healthy controls. The levels of APN and HMW-APN were all positively correlated with CRP levels. There was also positive correlation between HMW-APN levels and RF levels. Moreover, patients with higher disease activities had higher HMW-APN levels; patients with more severe synovial thickening had higher APN and HMW-APN levels. Therefore, APN, especially HMW-APN, may play a regulatory role in RA.

Association of circulating resistin and adiponectin levels with Kawasaki disease: A meta-analysis

The present meta-analysis was performed to examine the association between circulating blood adipokine levels and Kawasaki disease (KD). Studies were identified by searching various databases, including Web of Science, EMBASE, PubMed, Wanfang and China National Knowledge Infrastructure. After the studies were pooled, the mean difference (MD) and corresponding 95% CI were calculated. Subgroup analyses and publication bias detection were also performed. The Cochrane Q test and I² statistics were performed using Review Manager software (version 5.3) to test for heterogeneity. A Begg's test was used to assess publication bias and STATA software (version 12.0) was used for statistical analysis. The results revealed that the KD group exhibited higher levels of resistin compared with those in the healthy controls or disease controls (non-KD; MD=20.76, 95% CI=16.16-25.36, P<0.001; MD=21.27, 95% CI=14.24-28.29, P<0.001, respectively). In addition, when compared with those in patients exhibiting non-coronary artery lesions (NCAL), those with coronary artery lesions (CAL) had higher levels of adiponectin and resistin (MD=1.00, 95% CI=0.06-1.96, P=0.04; MD=2.77, 95% CI=1.32-4.22, P<0.001). Furthermore, compared with those in the inactive-phase group, patients in the active-phase group exhibited higher levels of resistin (MD=17.73, 95% CI=12.82-22.65, P<0.001). In conclusion, the present meta-analysis indicated that resistin levels were elevated in patients with KD. It was also revealed that circulating resistin and adiponectin levels in the CAL group were significantly increased compared with those in patients with NCAL. Furthermore, the active group had higher levels of resistin than the inactive group. The results of these meta-analyses indicated that resistin may serve an important role in the pathogenesis of KD and may therefore be used as biomarkers for the diagnosis of KD, whereas adiponectin may only serve an important role in the pathogenesis of CAL and may therefore be used as a biomarker to distinguish CAL from NCAL.

An update on pathogenesis of psoriatic arthritis and potential therapeutic targets

Introduction: Innate immune response and bone remodeling are key factors contributing to the pathogenesis of psoriatic arthritis (PsA). Moreover, the evidence of autoantibodies in patients' sera suggests an autoimmune side in PsA. Besides the immune pathways, studies strongly support the role of genetic risk alleles in affecting the clinical heterogeneity of PsA as well as the response to therapy. A good clinical response to treatment, indeed, represents a challenge in PsA patients and the identification of patient-targeted therapies is still a critical issue. Areas covered: We performed a systematic review aiming at describing new evidence on PsA pathogenesis and treatments. Reported items for systematic reviews (PRISMA checklist) were analyzed. Studies included from the PubMed database addressed the following items: innate immunity, autoimmunity, bone remodeling, and therapeutic targets in PsA; time frame of research 1970-2019. Specifically, we reviewed data on IL-17 inhibitors, abatacept, JAK inhibitors, ABT 122, and A (3) adenosine receptors agonist, CF101. Expert opinion: In PsA an intriguing pathogenetic network has been documented. Several biological and synthetic drugs are promising in terms of efficacy and safety profile.

G276T polymorphism in the ADIPOQ gene is associated with a reduced risk of polycystic ovarian syndrome: A meta-analysis of Asian population

OBJECTIVE

The etiology of polycystic ovarian syndrome (PCOS) has not yet been fully explained. Several studies suggested an association between two single nucleotide polymorphisms (T45G and G276T) of the ADIPOQ gene that encodes for the hormone adiponectin and PCOS susceptibility. Hence, we performed a meta-analysis to investigate the relationship of the two further.

MATERIALS AND METHODS

Literature search was conducted in PubMed up to June 22, 2018, for related publications written in English. Selected data were extracted from the included studies and was subjected to analysis using Review Manager 5.3. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed and pooled from the resulting studies. Subgroup analysis by ethnicity was also performed.

RESULTS

Overall analysis showed that women with the G276T polymorphism have reduced susceptibility to PCOS (OR: 0.68; 95% CI: 0.60-0.78; P^A < 0.001). While no significant association was observed for the T45G polymorphism (OR: 1.07; 95% CI: 0.93-1.24; P^A = 0.34). Subgroup analysis, on the other hand, showed significant associations among East Asians (OR: 0.69; 95% CI: 0.57-0.82; P^A < 0.001) for the G276T association.

CONCLUSION

Results of this meta-analysis suggests that women with the G276T polymorphism are less likely to develop PCOS. However, more studies are needed to confirm the claims of this meta-analysis.

Molecular Relationships among Obesity, Inflammation and Intervertebral Disc Degeneration: Are Adipokines the Common Link?

Intervertebral disc degeneration (IVDD) is a chronic, expensive, and high-incidence musculoskeletal disorder largely responsible for back/neck and radicular-related pain. It is characterized by progressive degenerative damage of intervertebral tissues along with metabolic alterations of all other vertebral tissues. Despite the high socio-economic impact of IVDD, little is known about its etiology and pathogenesis, and currently, no cure or specific treatments are available. Recent evidence indicates that besides abnormal and excessive mechanical loading, inflammation may be a crucial player in IVDD. Furthermore, obese adipose tissue is characterized by a persistent and low-grade production of systemic pro-inflammatory factors. In this context, chronic low-grade inflammation associated with obesity has been hypothesized as an important contributor to IVDD through different, but still unknown, mechanisms. Adipokines, such as leptin, produced prevalently by white adipose tissues, but also by other cells of mesenchymal origin, particularly cartilage and bone, are cytokine-like hormones involved in important physiologic and pathophysiological processes. Although initially restricted to metabolic functions, adipokines are now viewed as key players of the innate and adaptative immune system and active modulators of the acute and chronic inflammatory response. The goal of this review is to summarize the most recent findings regarding the interrelationships among inflammation, obesity and the pathogenic mechanisms involved in the IVDD, with particular emphasis on the contribution of adipokines and their potential as future therapeutic targets.

Nucleus-localized adiponectin is survival gatekeeper through miR-214-mediated AIFM2 regulation

Adiponectin secreted from adipocytes into plasma has anti-aging, anti-obesity and anti-inflammation effects. Here, we detected intracellular adiponectin localized in the nuclei of human and mouse pluripotent stem cells, mouse germ cells and some somatic cells. Nucleus-localized (Nu) adiponectin protein is characterized by an N-terminal truncated monomer form in a native state, compared with intact multimer forms of cytoplasm-localized (Cy) adiponectin protein. Doxycycline-induced over-expression of ADIPONECTIN caused cell death in human and mouse Nu-type pluripotent stem cells. Genome-wide gene expression analysis indicated that apoptosis by ADIPONECTIN over-expression was induced in accompany with upregulation of AIFM2 and MEG3. Upregulation of AIFM2 and MEG3 and down-regulation of miR-214-3p verified by qPCR analyses after ADIPONECTIN over-expression indicated that the MEG3/miR-214/AIFM2 pathway played a role in the apoptotic cell death of pluripotent cells. Adiponectin-induced cell death was rescued by the treatment with miR-214-3p mimic. Global data analysis shows that Nu adiponectin has a role in microRNA-mediated post-transcription regulation, cell-cell interactions and chromatin remodeling as a survival gatekeeper.

Adiponectin and sporadic Alzheimer's disease: Clinical and molecular links

Obesity has been consistently associated with Alzheimer's disease (AD) though the exact mechanisms by which it influences cognition are still elusive and subject of current research. Adiponectin, the most abundant adipokine in circulation, is inversely correlated with adipose tissue dysfunction and seems to be a central player in this association. In fact, different signalling pathways are shared by adiponectin and proteins involved in AD pathophysiology and considerable amount of evidence supports its direct and indirect influence on β-amyloid and tau aggregates formation. In this paper we present a critical review of cellular, animal and clinical studies which have contributed to a more thorough understanding of the extent to which adiponectin influences the risk of developing AD as well as its progression. Finally, the effect of acetylcholinesterase inhibitors on circulating adiponectin levels, possible therapeutic applications and future research strategies are also discussed.

Adiponectin profile at baseline is correlated to progression and severity of multiple sclerosis

BACKGROUND AND PURPOSE

Adiponectin is a cytokine linking energy metabolism and immune system. After being assembled, adiponectin circulates as oligomers of different molecular weight, i.e. low, medium and high (HMW) molecular weight. These have the most potent biological effects. Multiple sclerosis (MS) is an autoimmune disease of the human central nervous system. The aim of this study was to characterize the expression levels of both total adiponectin and its oligomerization state in the serum from 99 patients with MS at baseline (i.e. not influenced by therapies). We also investigated the potential relationships between adiponectin and disease progression and severity.

METHODS

Adiponectin was quantified and visualized by enzyme-linked immunosorbent assay, western blotting and fast protein liquid chromatography. During the follow-up (3.6 ± 2.20 years), the patients were evaluated using total annualized relapse rate and Expanded Disability Status Scale score.

RESULTS

Total adiponectin is statistically higher in patients with MS compared with matched controls (12.18 vs. 10.02 μg/mL, P = 0.001). Interestingly, the adiponectin oligomerization state is altered in MS, with an increase of HMW oligomers. In addition, patients with MS with higher levels of adiponectin at baseline have significantly higher risk of progression and severity (Multiple Sclerosis Severity Score, 3.84 vs. 2.44, P = 0.001). No statistical difference in adiponectin expression was found between active and inactive patients with MS and among the different forms of disease.

CONCLUSIONS

This study demonstrated that adiponectin and its HMW oligomers are greatly involved in MS autoimmune disorder representing a potential biomarker to predict worse MS prognosis and severity. Further studies are required to clarify the molecular mechanisms underlying the properties of adiponectin and HMW oligomers in MS.

Epicardial adipose tissue and atrial fibrillation: pathophysiological mechanisms, clinical implications, and potential therapies

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and is associated with increased cardiovascular morbidity and mortality. Epicardial adipose tissue (EAT) serves as a biologically active organ with important endocrine and inflammatory function. Review An accumulating body of evidence suggests that EAT is associated with the initiation, perpetuation, and recurrence of AF, but the precise role of EAT in AF pathogenesis is not completely elucidated. Pathophysiological mechanisms involve adipocyte infiltration, profibrotic and pro-inflammatory paracrine effects, oxidative stress, neural mechanisms, and genetic factors.

CONCLUSIONS

Notably, EAT accumulation seems to be associated with stroke and adverse cardiovascular outcomes in AF. Weight loss, specific medications and ablation of ganglionated plexi (GP) seem to be potential therapies in this setting.

Endocrine Adiponectin-FGF15/19 Axis in Ethanol-Induced Inflammation and Alcoholic Liver Injury

Alcoholic liver disease (ALD) is the most prevalent form of liver disease, encompassing a spectrum of progressive pathological changes from steatosis to steatohepatitis to fibrosis/cirrhosis and hepatocellular carcinoma. Alcoholic steatosis/steatohepatitis is the initial stage of ALD and a major risk factor for advanced liver injuries. Adiponectin is a hormone secreted from adipocytes. Fibroblast growth factor (FGF) 15 (human homolog, FGF19) is an ileum-derived hormone. Adipocyte-derived adiponectin and gut-derived FGF15/19 regulate each other, share common signaling cascades, and exert similar beneficial functions. Emerging evidence has revealed that dysregulated adiponectin-FGF15/19 axis and impaired hepatic adiponectin-FGF15/19 signaling are associated with alcoholic liver damage in rodents and humans. More importantly, endocrine adiponectin-FGF15/19 signaling confers protection against ethanol-induced liver damage via fine tuning the adipose-intestine-liver crosstalk, leading to limited hepatic inflammatory responses, and ameliorated alcoholic liver injury. This review is focused on the recently discovered endocrine adiponectin-FGF15/19 axis that is emerging as an essential adipose-gut-liver coordinator involved in the development and progression of alcoholic steatohepatitis.

Adipokines and inflammation: is it a question of weight?

Obesity has reached epidemic proportions in the Western society and is increasing in the developing world. It is considered as one of the major contributors to the global burden of disability and chronic diseases, including autoimmune, inflammatory and degenerative diseases. Research conducted on obesity and its complications over the last two decades has transformed the outdated concept of white adipose tissue (WAT) merely serving as an energy depot. WAT is now recognized as an active and inflammatory organ capable of producing a wide variety of factors known as adipokines. These molecules participate through endocrine, paracrine, autocrine or juxtacrine crosstalk mechanisms in a great variety of physiological or pathophysiological processes, regulating food intake, insulin sensitivity, immunity and inflammation. Although initially restricted to metabolic activities (regulation of glucose and lipid metabolism), adipokines currently represent a new family of proteins that can be considered key players in the complex network of soluble mediators involved in the pathophysiology of immune/inflammatory diseases. However, the complexity of the adipokine network in the pathogenesis and progression of inflammatory diseases has posed, since the beginning, the important question of whether it may be possible to target the mechanism(s) by which adipokines contribute to disease selectively without suppressing their physiological functions. Here, we explore in depth the most recent findings concerning the involvement of adipokines in inflammation and immune responses, in particular in rheumatic, inflammatory and degenerative diseases. We also highlight several possible strategies for therapeutic development and propose that adipokines and their signalling pathways may represent innovative therapeutic strategies for inflammatory disorders.

Lower Levels of Serum Adiponectin and the T Allele of rs1501299 of the ADIPOQ Gene Are Protective against Polycystic Ovarian Syndrome in Jordan

Background

Polycystic ovary syndrome (PCOS) is a common reproductive disorder. Obesity, which is linked with lower adiponectin levels, increases a woman's risk of developing PCOS; however, the association between adiponectin and PCOS is controversial. Adiponectin levels could be affected by single nucleotide polymorphisms (SNPs) in the ADIPOQ gene. This study aimed to test the relationship between serum adiponectin and PCOS in Jordan and the association between the rs2241766, rs1501299, and rs266729 SNPs in the ADIPOQ gene and PCOS.

Methods

One hundred and fifty-four women with PCOS and 149 age- and body mass index-matched normally menstruating controls were recruited. Serum adiponectin levels were measured using enzyme-linked immunosorbent assay. Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism analysis.

Results

Serum adiponectin levels were significantly lower (P=0.0064) in PCOS women and rs1501299 (+276 G/T) genotype distributions were significantly different (P=0.01) between them and normally menstruating women. Multivariate analysis revealed that adiponectin levels remained significantly lower in PCOS women (P=0.001; odds ratio [OR], 0.9; 95% confidence interval [CI], 0.84-0.96). The GT genotype of rs1501299 increased the risk of PCOS (P<0.001; OR, 5.46; 95% CI, 2.42-12.33) and increased the risk of PCOS by three-fold (P<0.001; OR, 3.00; 95% CI, 1.36-6.60) relative to the TT genotype. The GG genotype increased the risk of PCOS as well (P<0.001; OR, 3:00; 95% CI, 1.36-6.60).

Conclusion

PCOS is associated with lower serum adiponectin levels independent of age and body mass index. The T allele of the rs1501299 (+276 G/T) SNP of the ADIPOQ gene protects against PCOS.

Tachykinin neurokinin 3 receptor antagonists: a new treatment for cardiovascular disease?

Great progress has been made in reducing cardiovascular mortality over the past 50 years. Nevertheless, prevalence is rising in some settings and remains higher in men than in women, even with the same level of established risk factors. To gain new insights, researchers are now considering cardiovascular disease in relation to the well known evolutionary biology model of growth and reproduction trading off against longevity, with trials of calorie restriction underway. However, calorie restriction has not been as successful as expected in primates and it is increasingly realised that effects on the reproductive axis might also be important. In this paper, the modulation of the reproductive axis using existing agents that have such properties-tachykinin neurokinin 3 receptor antagonists-is proposed as a way of reducing cardiovascular disease and combating a leading cause of global morbidity and mortality.

Adiponectin exerts a potent anti-arthritic effect and insulin resistance in collagen-induced arthritic rats

AIM

Previous research has shown that adiponectin (AD) induces severe insulin resistance (IR) and exhibits pro-inflammatory effect, so it could serve as a useful risk biomarker in rheumatoid arthritis (RA). The present study aims to evaluate the effect of AD on IR and anti-arthritis in collagen-induced arthritic (CIA) rats.

METHOD

After immunization with bovine type II collagen (CII), Wistar rats were administered with AD (60 μg/kg/day) or saline into the ankle joint cavity of the left hind leg for 15 days. The severity of arthritis was clinically and histologically assessed. Arthritis score was recorded every other day for each paw. Paw volume was measured on alternate days to monitor the progression of the disease in the arthritic control group. Tumor necrosis factor (TNF)-α, interleukin (IL)-1, AD, insulin and fasting glucose were measured in sera. Histopathology of joint synovial tissues was also examined.

RESULTS

Treatment with AD resulted in significantly delayed onset of arthritis as well as decreased clinical arthritis and histopathological severity scores. AD reduced both serum fasting glucose, TNF-α, IL-1 and IR. Histological analysis confirmed treatment with AD suppressed joint synovial inflammation and immunohistochemical expression of TNF-α compared to the CIA group. Surprisingly, adiponectin levels measured by enzyme-linked immunosorbent assay in serum were significantly increased in CIA rats compared to the normal group.

CONCLUSIONS

Adiponectin might display anti-inflammatory effects. These results suggest that AD may be a potential immunosuppressant for the treatment of RA linked to metabolic disease.

CTRP1 in Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease occurs in significant percentage of general population. NAFLD is closely associated with entire spectrum of metabolic-related disorders including diabetes, obesity, and cardiovascular diseases. Considering several similar pathways underpinning metabolic disorders, presence of common molecular mediators contributing to pathomechanism of these disorders is expected. Mounting evidence has demonstrated important role of adipokines in the context of NAFLD. Adipokines produced by different tissues, mainly adipose, modulate numerous pathways including glucose and fatty acid metabolism and inflammation. CTRPs (C1q/TNF-related proteins) are a recently identified family of adipokines in which adiponectin is the most well-known ones. CTRP1 is a member of this family which has captured attention in recent years. CTRP1 enhances glucose and fatty acid oxidation, improves insulin sensitivity, attenuates plaque formation, and increases aldosterone production. Hence, various roles in metabolic pathways can link CTRP1 to NAFLD pathogenesis.

Obesity and cancer: the role of adipose tissue and adipo-cytokines-induced chronic inflammation

Adipose tissue in addition to its ability to keep lipids is now recognized as a real organ with both metabolic and endocrine functions. Recent studies demonstrated that in obese animals is established a status of adipocyte hypoxia and in this hypoxic state interaction between adipocytes and stromal vascular cells contribute to tumor development and progression. In several tumors such as breast, colon, liver and prostate, obesity represents a poor predictor of clinical outcomes. Dysfunctional adipose tissue in obesity releases a disturbed profile of adipokines with elevated levels of pro-inflammatory factors and a consequent alteration of key signaling mediators which may be an active local player in establishing the peritumoral environment promoting tumor growth and progression. Therefore, adipose tissue hypoxia might contribute to cancer risk in the obese population. To date the precise mechanisms behind this obesity-cancer link is not yet fully understood. In the light of information provided in this review that aims to identify the key mechanisms underlying the link between obesity and cancer we support that inflammatory state specific of obesity may be important in obesity-cancer link.

Leukocytes apoptosis and adipocytokines in children with beta thalassemia major

β-Thalassemia is a significant public health problem in Egypt. Infectious complications represent the second most common cause of mortality and the major cause of morbidity in β-thalassemia major (BTM). The increased susceptibility of these patients to infectious diseases has been attributed to the abnormalities of the immune system, which is evident by systemic inflammation and immune deficiency. In a case control study, 35 patients with BTM were compared with 30 sex- and age-matched children who served as controls. Serum ferritin, high-sensitive CRP (hsCRP), leptin and adiponectin levels were determined in all subjects. Apoptosis of neutrophils and lymphocytes was measured by the Annexin V-fluoroisothiocyanate binding assay. Serum leptin was significantly lower in patients when compared to controls. In contrast, adiponectin and hsCRP levels were significantly higher in the patients than the controls. Positive correlation was found between adiponectin and hsCRP. BTM patients had significantly higher total leukocytes, neutrophils and lymphocytes compared with controls. BTM children exhibited a significantly increased apoptosis in T-lymphocytes; however, there was no significant difference in the percentage of apoptosis of B-lymphocytes and neutrophils between the patients and the controls. There was a significant negative correlation between serum leptin and the percentage of apoptotic T-lymphocytes. Our BTM patients had a high percentage of apoptotic T-lymphocyte in comparison with controls. In addition, they had disturbed serum levels of adipocytokines and inflammatory markers. These derangements could have a role in the immunological disturbance observed in thalassemic patients.

Adiponectin: A biomarker for chronic hepatitis C?

Adiponectin, a hormone primarily synthesized and secreted by adipose tissue, plays a pivotal role in lipid metabolism. Chronic hepatitis C (CHC) infection is characterized by disordered lipid metabolism, which may potentially evolve into steatosis over a period of time. A growing body of evidence appears to link decreased adiponectin plasma levels with severe CHC-related steatosis, which suggests a potential role of this adipokine as a diagnostic and therapeutic target for clinical application. In this review, we have attempted to summarize the current status of adiponectin research in the context of CHC, concentrating predominantly on its roles in CHC, and its potential relevance as a biomarker for CHC.

Adipokines influence the inflammatory balance in autoimmunity

Over the past few decades, our understanding of the role of adipose tissue has changed dramatically. Far from simply being a site of energy storage or a modulator of the endocrine system, adipose tissue has emerged as an important regulator of multiple important processes including inflammation. Adipokines are a diverse family of soluble mediators with a range of specific actions on the immune response. Autoimmune diseases are perpetuated by chronic inflammatory responses but the exact etiology of these diseases remains elusive. While researchers continue to investigate these causes, millions of people continue to suffer from chronic diseases. To this end, an increased interest has developed in the connection between adipose tissue-secreted proteins that influence inflammation and the onset and perpetuation of autoimmunity. This review will focus on recent advances in adipokine research with specific attention on a subset of adipokines that have been associated with autoimmune diseases.

Effect of ketotifen in obese patients with type 2 diabetes mellitus

AIM

Mast cells are found to be an important contributor in obesity induced insulin resistance. We evaluate the effect of ketotifen in obese patient with type 2 diabetes (T2DM) treated with glimepiride.

METHOD

In a randomized controlled study we recruited forty-eight obese patients with T2DM from Internal Medicine Department at Tanta University Hospital, Egypt. They were classified into three groups: group 1, those who received glimepiride (GL) 3mg/d alone; group 2, those who received GL 3mg/d+ketotifen 1mg once daily; and group 3, those who received GL 3mg/d+ketotifen 1mg twice daily. Fasting blood samples were obtained before and 12weeks after treatment for biochemical analysis of glycemic and inflammatory biomarkers. Data were statistically analyzed by paired Student's t-test and one way analysis of variance; p<0.05 was considered statistically significant.

RESULTS

The obtained data suggested that the addition of ketotifen in twice daily dose has a beneficial effect on all measured parameters except adiponectin. However, glimepiride plus ketotifen once daily only affected the level of inflammatory biomarkers without any significant effect on other parameters.

CONCLUSIONS

The co-administration of ketotifen twice daily plus glimepiride improves glycemic and inflammatory process in obese patients with T2DM.

The Concise Guide to PHARMACOLOGY 2013/14: overview

The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties from the IUPHAR database. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. This compilation of the major pharmacological targets is divided into seven areas of focus: G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors & Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and GRAC and provides a permanent, citable, point-in-time record that will survive database updates.

Adiponectin attenuates osteolysis in aseptic loosening of total hip replacements

Joint replacements have a longer durability in patients with high serum levels of adiponectin (APN) than in patients with low levels. We aimed to characterize the unknown pathophysiological effects of APN on wear particle-induced inflammation, apoptosis and osteolysis. Immunohistochemistry was performed to detect APN, its receptors and apoptosis in patients with and without aseptic loosening. Additionally, APN knockout mouse studies and pharmacological intervention of APN were performed in an established calvarial mouse model. Osteolysis and inflammation were quantified by histomorphometry and microcomputed tomography, apoptosis by immunohistochemistry and TUNEL assay. In a cell culture model, human monocyte-derived macrophages were incubated with or without metal wear debris particles and partially treated with APN. Expression of APN, AdipoR1 and calreticulin in specimens from patients with aseptic loosening were significantly higher than in patients without aseptic loosening. Administration of APN in mice significantly reduced wear particle-induced inflammation, osteolysis and the number of caspase-3-positive macrophages. The cell culture model showed that APN leads to significantly lower values of TNF-α. These findings support a prominent role of APN in the development of particle-induced osteolysis and APN may be therapeutically useful in patients with aseptic loosening.

Adiponectin modulates DCA-induced inflammation via the ROS/NF-κ B signaling pathway in esophageal adenocarcinoma cells

BACKGROUND

Deoxycholic acid (DCA) promotes the development and progression of esophageal adenocarcinoma (EAC) by inducing inflammation. Adiponectin is reported to have anti-inflammatory and anti-tumor effects.

PURPOSE

This study investigated the effects of two types of adiponectin, full-length adiponectin (f-Ad) and globular adiponectin (g-Ad), on DCA-induced inflammation, and investigated the involvement of the reactive oxygen species (ROS)/NF-κB signaling pathway in inflammation in EAC.

METHODS

OE19 cells were treated with DCA (50-300 μM) and/or f-Ad/g-Ad (10.0 μg/ml) or N-acetylcysteine (NAC). The viability of cells exposed to DCA was measured by use of the MTT assay. mRNA and protein levels of the inflammatory factors were examined by real-time PCR and ELISA. Intra-cellular ROS levels were determined by use of flow cytometry. Protein levels of total and p-NF-κB p65 were measured by western blot.

RESULTS

DCA induced dose and time-dependent cytotoxicity. mRNA and protein expression of TNF-α, IL-8, and IL-6 in cells treated with DCA alone were up-regulated, and intra-cellular ROS and p-NF-κB p65 protein levels were also increased. g-Ad promoted inflammatory factor production, ROS levels, and p-NF-κB p65 protein expression whereas f-Ad had a suppressive effect. When combined with DCA, g-Ad enhanced the pro-inflammatory effect of DCA whereas f-Ad, similar to NAC, suppressed the effect.

CONCLUSION

DCA has a pro-inflammatory effect in EAC. f-Ad has an anti-inflammatory effect whereas g-Ad seems to have a pro-inflammatory effect in an ROS/NF-κB p65-dependent manner. This indicates that f-Ad could be a potential anti-inflammatory reagent for cancer therapy.

Obesity, high-molecular-weight (HMW) adiponectin, and metabolic risk factors: prevalence and gender-specific associations in Estonia

Background

The metabolic consequences of obesity are associated with an imbalance of adipocytokines, e.g. adiponectin. However, some obese subjects remain metabolically healthy and have adiponectin levels similar to normal body weight subjects. Current estimates of the prevalence of obesity in Estonia have relied only on self-report data.

Objectives

To estimate the prevalence of obesity in Estonia, to test for associations between HMW adiponectin and metabolic risk factors and to test if HMW adiponectin levels differentiate metabolically healthy and metabolically unhealthy subjects.

Methods

We conducted a population-based cross-sectional multicentre study to gather history, examination and blood test results for 495 subjects aged 20–74. Metabolically healthy subjects were free from hypertension, dyslipidaemia, impaired glucose regulation and insulin resistance. Metabolically unhealthy subjects had at least one of these four metabolic abnormalities.

Results

The prevalence of obesity was 29% in men and 34% in women. HMW adiponectin was positively correlated with HDL cholesterol and negatively correlated with triglycerides, obesity, insulin resistance and blood glucose. This effect was driven by metabolically unhealthy subjects in men, but by both metabolically healthy and metabolically unhealthy subjects in women. Metabolically healthy women had higher HMW adiponectin levels than metabolically unhealthy women. 12% of all obese subjects were metabolically healthy, and their HMW adiponectin levels were similar to normal weight subjects.

Conclusions

Obesity is more prevalent in Estonian adults than previously thought. HMW adiponectin levels were associated with various metabolic risk factors in metabolically healthy women but not in metabolically healthy men. For both genders, HMW adiponectin differentiates metabolically healthy obese subjects from metabolically unhealthy obese subjects.

Identification of adiponectin receptor agonist utilizing a fluorescence polarization based high throughput assay

Adiponectin, the adipose-derived hormone, plays an important role in the suppression of metabolic disorders that can result in type 2 diabetes, obesity, and atherosclerosis. It has been shown that up-regulation of adiponectin or adiponectin receptor has a number of therapeutic benefits. Given that it is hard to convert the full size adiponectin protein into a viable drug, adiponectin receptor agonists could be designed or identified using high-throughput screening. Here, we report on the development of a two-step screening process to identify adiponectin agonists. First step, we developed a high throughput screening assay based on fluorescence polarization to identify adiponectin ligands. The fluorescence polarization assay reported here could be adapted to screening against larger small molecular compound libraries. A natural product library containing 10,000 compounds was screened and 9 hits were selected for validation. These compounds have been taken for the second-step in vitro tests to confirm their agonistic activity. The most active adiponectin receptor 1 agonists are matairesinol, arctiin, (-)-arctigenin and gramine. The most active adiponectin receptor 2 agonists are parthenolide, taxifoliol, deoxyschizandrin, and syringin. These compounds may be useful drug candidates for hypoadiponectin related diseases.

Serum total adiponectin level and the risk of cardiovascular disease in general population: a meta-analysis of 17 prospective studies

OBJECTIVE

Many studies have assessed the association between serum adiponectin and the risk of cardiovascular disease (CVD), yet whether adiponectin is an independent risk factor for CVD remains controversial. We performed a meta-analysis of 17 prospective epidemiologic studies to evaluate this relationship in the general population.

METHODS

PubMed and Embase databases were searched through June 2012 to identify studies meeting a priori inclusion criteria, in addition to conducting a secondary reference review. Two principle investigators respectively extracted the information with either fixed-effect model or random-effect model to calculate the relationship between adiponectin and the risk of CVD.

RESULTS

We summarized 17 prospective studies with a total of 23,717 participants. Overall, higher serum adiponectin was related to an increased risk of ischemic stroke: pooled risk ratio (RR) of 1.34 [95% confidence intervals (CI): 1.06-1.69] with no heterogeneity (Q = 1.23; P = 0.541). Serum adiponectin was not related to coronary heart disease (CHD) or CVD: pooled RR of 0.96 (95% CI: 0.85-1.08) and 1.00 (95% CI: 0.89-1.13), respectively.

CONCLUSIONS

Increased serum adiponectin was related to an elevated risk of ischemic stroke, but there was no clear evidence indicating a positive relationship between adiponectin and the risk of CHD or CVD.

Genetic deficiency of adiponectin protects against acute kidney injury

Adiponectin is a multifunctional cytokine that has a role in regulating inflammation. Here we determined if adiponectin modulates ischemic acute kidney injury. Compared with wild-type mice, adiponectin knockout mice were found to have lower serum creatinine and less tubular damage or apoptosis following ischemia/reperfusion injury. This latter process was associated with decreased Bax and reduced activation of p53 and caspase-3. Targeted disruption of adiponectin was also found to inhibit the infiltration of neutrophils, macrophages, and T cells into the injured kidneys. This was associated with an inhibition of NF-κB activation and reduced expression of the proinflammatory molecules IL-6, TNF-α, MCP-1, and MIP-2 in the kidney after ischemia/reperfusion injury. Wild-type mice engrafted with adiponectin null bone marrow had less kidney dysfunction and tubular damage than adiponectin null mice engrafted with wild-type bone marrow. Conversely, adiponectin null mice engrafted with wild-type bone marrow had similar renal dysfunction and tubular damage compared to wild-type mice engrafted with wild-type bone marrow. In cultured macrophages, adiponectin directly promoted macrophage migration; a process blocked by the PI3 kinase inhibitor, LY294002. Thus, our results show that adiponectin plays a pivotal role in the pathogenesis of acute renal ischemia/reperfusion injury and may be a potential therapeutic target.

Adiponectin: a biomarker for rheumatoid arthritis?

Recent achievements in the biology and the function of adipose tissue have regarded white adipose tissue (WAT) as an important endocrine and secretory organ. Releasing a series of multiple-function mediators, WAT is involved in a wide spectrum of diseases, including not only cardiovascular and metabolic complications, such as atherosclerosis and type 2 diabetes, but also inflammatory- and immune-related disorders, such as rheumatoid arthritis (RA) and osteoarthritis (OA). A large number of these mediators, called adipokines, such as tumor necrosis factor alpha (TNF-α), leptin, adiponectin, resistin, chemerin, interleukin-6 (IL-6), visfatin, and so on have been identified and studied widely. Important advances related to these proteins shed new insights into the pathophysiological mechanisms of many complicated diseases, although details of which remain unclear. Adiponectin, one of the most widely investigated adipokine, has been shown to possess both anti- and pro-inflammatory effects. RA is a chronic systemic inflammatory-related autoimmune disease. Accumulated evidence has demonstrated that cytokines and adipokines play an important role in the pathogenesis of RA. In this review, we have summarized the most recent advances in adiponectin research in the context of RA, focusing primarily on its effect on RA-related cells, its regulation on pro-inflammatory cytokines, as well as its validation as a biomarker for RA.

Inhibitory role of adiponectin peptide I on rat choroidal neovascularization

Age-related macular degeneration (AMD) is a leading cause of central blindness in the elderly population. The wet type of AMD is characterized by extensive growth of new vessels. One of the effective strategies to treat wet AMD is to limit the choroidal neovascularization (CNV). We studied the effects of adiponectin peptide I (APNpI) on new vessel growth in laser-induced rat model of wet AMD and on rat choroidal endothelial cell (CEC) culture. CNV size and vessel density were investigated by microscopy. Immunohistochemical staining (IHC) for von Willebrand Factor (vWF), APN, APN receptors 1 (AdipoR1), 2 (AdipoR2), VEGF, VEGF receptor 2 (VEGF-R2), proliferating cell nuclear antigen (PCNA) was performed in CNV area. The mRNA expression of VEGF and VEGF-R2 in RPE-choroid was investigated by RT-PCR and real-time PCR. APNpI inhibited area of CNV by 4 fold, number of vWF positive vessels by 99% and area of subretinal tissue by 40%. The expression of VEGF and VEGF-R2 at mRNA and protein levels decreased after APNpI treatment in vivo. Proliferative index (PCNA) was 5 folds less in laser spots of APNpI treated rats compared to controls. In conclusion, APNpI inhibited formation of new vessels in rat model of CNV by decreasing VEGF, VEGF-R2 expression and cell proliferation. Thus, APNpI may have potential therapeutic use for AMD treatment since it significantly inhibited CNV.

The therapeutic potential of the adiponectin pathway

Adiponectin is an adipocyte-derived hormone that has been shown to play an important role in the regulation of metabolic, inflammatory, and apoptotic pathways. Adiponectin improves insulin sensitivity, promotes vascular health, and increases cell survival. These observations suggest a potential therapeutic role for adiponectin in the treatment of diabetes mellitus, cardiovascular diseases, and cancer. However, biologically active recombinant adiponectin proteins are inherently unstable and difficult to produce, thus making it a challenge for both research and clinical development. One main challenge relates to the existence of adiponectin as homo-/hetero-trimers, and complexes containing multiple adiponectin trimer units, in plasma. The underlying mechanism for adiponectin function is also not completely understood. Two receptors for adiponectin (ADIPOR1 and ADIPOR2) have been cloned, and activation of adenosine monophosphate-activated kinase (AMPK) has been reported to be downstream of the receptors. Recent findings suggest that adiponectin potently stimulates ceramidase activity via activation of its two known receptors, therefore connecting sphingolipid metabolism to adiponectin functions and providing a potential mechanism explaining the different actions of adiponectin. Interestingly, a new report also identified a pathway involving adiponectin and insulin receptor substrate 2, which is independent of the ADIPOR1/ADIPOR2 pathway. In this manuscript, we will review previous approaches and challenges in exploring adiponectin-based therapeutics. In particular, we will review some of the recent developments in engineering adiponectin proteins as well as potential therapeutic opportunities offered by recently elucidated adiponectin-mediated signaling pathways.

Sex hormone activity in alcohol addiction: integrating organizational and activational effects

There are well-known sex differences in the epidemiology and etiopathology of alcohol dependence. Male gender is a crucial risk factor for the onset of alcohol addiction. A directly modifying role of testosterone in alcohol addiction-related behavior is well established. Sex hormones exert both permanent (organizational) and transient (activational) effects on the human brain. The sensitive period for these effects lasts throughout life. In this article, we present a novel early sex hormone activity model of alcohol addiction. We propose that early exposure to sex hormones triggers structural (organizational) neuroadaptations. These neuroadaptations affect cellular and behavioral responses to adult sex hormones, sensitize the brain's reward system to the reinforcing properties of alcohol and modulate alcohol addictive behavior later in life. This review outlines clinical findings related to the early sex hormone activity model of alcohol addiction (handedness, the second-to-fourth-finger length ratio, and the androgen receptor and aromatase) and includes clinical and preclinical literature regarding the activational effects of sex hormones in alcohol drinking behavior. Furthermore, we discuss the role of the hypothalamic-pituitary-adrenal and -gonadal axes and the opioid system in mediating the relationship between sex hormone activity and alcohol dependence. We conclude that a combination of exposure to sex hormones in utero and during early development contributes to the risk of alcohol addiction later in life. The early sex hormone activity model of alcohol addiction may prove to be a valuable tool in the development of preventive and therapeutic strategies.

Adiponectin associates with markers of cartilage degradation in osteoarthritis and induces production of proinflammatory and catabolic factors through mitogen-activated protein kinase pathways

Introduction

Adiponectin is an adipokine that regulates energy metabolism and insulin sensitivity, but recent studies have pointed also to a role in inflammation and arthritis. The purpose of the present study was to investigate the association and effects of adiponectin on inflammation and cartilage destruction in osteoarthritis (OA).

Methods

Cartilage and blood samples were collected from 35 male OA patients undergoing total knee replacement surgery. Preoperative radiographs were evaluated using Ahlbäck classification criteria for knee OA. Circulating concentrations of adiponectin and biomarkers of OA, that is, cartilage oligomeric matrix protein (COMP) and matrix metalloproteinase 3 (MMP-3), were measured. Cartilage samples obtained at the time of surgery were cultured ex vivo, and the levels of adiponectin, nitric oxide (NO), IL-6, MMP-1 and MMP-3 were determined in the culture media. In addition, the effects of adiponectin on the production of NO, IL-6, MMP-1 and MMP-3 were studied in cartilage and in primary chondrocyte cultures.

Results

Plasma adiponectin levels and adiponectin released from OA cartilage were higher in patients with the radiologically most severe OA (Ahlbäck grades 4 and 5) than in patients with less severe disease (Ahlbäck grades 1 to 3). Plasma adiponectin concentrations correlated positively with biomarkers of OA, that is, COMP (r = 0.55, P = 0.001) and MMP-3 (r = 0.34, P = 0.046). Adiponectin was released by OA cartilage ex vivo, and it correlated positively with production of NO (r = 0.43, P = 0.012), IL-6 (r = 0.42, P = 0.018) and MMP-3 (r = 0.34, P = 0.051). Furthermore, adiponectin enhanced production of NO, IL-6, MMP-1 and MMP-3 in OA cartilage and in primary chondrocytes in vitro in a mitogen-activated protein kinase (MAPK)-dependent manner.

Conclusions

The findings of this study show that adiponectin is associated with, and possibly mediates, cartilage destruction in OA.

Globular domain of adiponectin: promising target molecule for detection of atherosclerotic lesions

BACKGROUND

Adiponectin, an adipocyte-specific plasma protein, has been shown to accumulate in injured endothelial cells during development of atherosclerotic lesions. In this study, we investigated the potential of different adiponectin subfractions with special emphasis on globular adiponectin (gAd) to recognize and visualize atherosclerotic lesions.

METHODS

Recombinant mouse gAd and subfractions of full-length adiponectin (ie, trimeric, hexameric, and oligomeric forms) were fluorescence-labeled. Aortas of wild-type and apoprotein E-deficient mice fed a high cholesterol diet were dissected and incubated with the labeled biomarkers. Imaging was performed using confocal laser scanning microscopy.

RESULTS

Confocal laser scanning microscopic images showed that gAd binds more strongly to atherosclerotic plaques than full-length adiponectin subfractions. Further, we showed that gAd accumulates preferentially in endothelial cells and the fibrous cap area of plaques. Here we demonstrate for the first time that gAd recognizes atherosclerotic plaques on aortic sections of apoprotein E-deficient mice.

CONCLUSION

These results suggest that gAd, in addition to its physiological properties, is also suitable as a target molecule for prospective diagnostic strategies in imaging atherosclerotic lesions.