A genome-wide association study reveals a quantitative trait locus of adiponectin on CDH13 that predicts cardiometabolic outcomes

Genome-wide placental DNA methylations in fetal overgrowth and associations with leptin, adiponectin and fetal growth factors

BACKGROUND

Fetal overgrowth "programs" an elevated risk of type 2 diabetes in adulthood. Epigenetic alterations may be a mechanism in programming the vulnerability. We sought to characterize genome-wide alterations in placental gene methylations in fetal overgrowth and the associations with metabolic health biomarkers including leptin, adiponectin and fetal growth factors.

RESULTS

Comparing genome-wide placental gene DNA methylations in large-for-gestational-age (LGA, an indicator of fetal overgrowth, n = 30) versus optimal-for-gestational-age (OGA, control, n = 30) infants using the Illumina Infinium Human Methylation-EPIC BeadChip, we identified 543 differential methylation positions (DMPs; 397 hypermethylated, 146 hypomethylated) at false discovery rate < 5% and absolute methylation difference > 0.05 after adjusting for placental cell-type heterogeneity, maternal age, pre-pregnancy BMI and HbA1c levels during pregnancy. Twenty-five DMPs annotated to 20 genes (QSOX1, FCHSD2, LOC101928162, ADGRB3, GCNT1, TAP1, MYO16, NAV1, ATP8A2, LBXCOR1, EN2, INCA1, CAMTA2, SORCS2, SLC4A4, RPA3, UMAD1,USP53, OR2L13 and NR3C2) could explain 80% of the birth weight variations. Pathway analyses did not detect any statistically significant pathways after correcting for multiple tests. We validated a newly discovered differentially (hyper-)methylated gene-visual system homeobox 1 (VSX1) in an independent pyrosequencing study sample (LGA 47, OGA 47). Our data confirmed a hypermethylated gene-cadherin 13 (CDH13) reported in a previous epigenome-wide association study. Adiponectin in cord blood was correlated with its gene methylation in the placenta, while leptin and fetal growth factors (insulin, IGF-1, IGF-2) were not.

CONCLUSIONS

Fetal overgrowth may be associated with a large number of altered placental gene methylations. Placental VSX1 and CDH13 genes are hypermethylated in fetal overgrowth. Placental ADIPOQ gene methylations and fetal circulating adiponectin levels were correlated, suggesting the contribution of placenta-originated adiponectin to cord blood adiponectin.

Twin Study: Genetic and Epigenetic Factors Affecting Circulating Adiponectin Levels

CONTEXT

Clarification of the association among phenotypes, genetic, and environmental factors with clinical laboratory traits can reveal the cause of diseases and assist in developing methods for the prediction and prevention of diseases. It is difficult to investigate the environmental effect on phenotypes using individual samples because their genetic and environmental factors differ, but we can easily investigate the influence of environmental factors using monozygotic (MZ) twins because they have the same genetic factors.

OBJECTIVE

We aimed to examine the methylation level of CpG sites as an environmental factor affecting adiponectin levels on the basis of the same genetic background using MZ twins and to identify the epigenetic factors related to adiponectin levels and the genetic factors associated with sensitivity to acquired changes in adiponectin.

METHODS

Using 2 groups built from each twin of 232 MZ twin pairs, we performed a replicated epigenome-wide association study to clarify the epigenetic factors affecting adiponectin levels adjusted by genetic risk score. Moreover, we divided twin pairs into concordant and discordant for adiponectin levels. We conducted a genome-wide association study to identify a genetic background specific for discordance.

RESULTS

Methylation levels at 38 CpG sites were reproducibly associated with adjusted adiponectin levels, and some of these CpG sites were in genes related to adiponectin, including CDH13. Some genes related to adiponectin or insulin resistance were found to be genetic factors specific for discordance.

CONCLUSION

We clarified specific epigenetic factors affecting adiponectin levels and genetic factors associated with sensitivity to acquired changes in adiponectin.

Time-Series Change of Serum Soluble T-Cadherin Concentrations and Its Association with Creatine Kinase-MB Levels in ST-Segment Elevation Myocardial Infarction

AIMS

T-cadherin (T-cad) is a specific binding partner of adiponectin (APN), adipocyte-specific secretory protein. APN exhibits organ protection via the T-cad-dependent accumulation onto several tissues such as the aorta, heart, and muscle. Recently, for the first time, we showed that three forms (130, 100, and 30 kDa) of soluble T-cad existed in human serum and correlated with several clinical parameters in patients with type 2 diabetes. Nevertheless, the significance of soluble T-cad has not been elucidated in the acute stage of cardiovascular diseases. We herein examined soluble T-cad concentrations and investigated their clinical significance in patients with emergency hospital admission due to ST-segment elevation myocardial infarction (STEMI).

METHODS

This observational study enrolled 47 patients with STEMI who were treated via primary percutaneous coronary intervention (PCI). Soluble T-cad and APN concentrations were measured by using an enzyme-linked immunosorbent assay. This study is registered with the University Hospital Medical Information Network (Number: UMIN 000014418).

RESULTS

Serum concentrations of soluble 130 and 100 kDa T-cad rapidly and significantly decreased after hospitalization and reached the bottom at 72 h after admission (p＜0.001 and p＜0.001, respectively). The patients with high soluble T-cad and low APN concentrations on admission showed a significantly higher area under the curve of serum creatine kinase-MB (p＜0.01).

CONCLUSION

Serum soluble T-cad concentration changed dramatically in patients with STEMI, and the high T-cad and low APN concentrations on admission were associated with the myocardial infarction size. Further study is needed to investigate the usefulness of categorizing patients with STEMI by serum T-cad and APN for the prediction of severe prognoses.

Chromosome-level genome assembly of the Muscovy duck provides insight into fatty liver susceptibility

The Muscovy duck (Cairina moschata) is an economically important poultry species, which is susceptible to fatty liver. Thus, the Muscovy duck may serve as an excellent candidate animal model of non-alcoholic fatty liver disease. However, the mechanisms underlying fatty liver development in this species are poorly understood. In this study, we report a chromosome-level genome assembly of the Muscovy duck, with a contig N50 of 11.8 Mb and scaffold N50 of 83.16 Mb. The susceptibility of Muscovy duck to fatty liver was mainly attributed to weak lipid catabolism capabilities (fatty acid β-oxidation and lipolysis). Furthermore, conserved noncoding elements (CNEs) showing accelerated evolution contributed to fatty liver formation by down-regulating the expression of genes involved in hepatic lipid catabolism. We propose that the susceptibility of Muscovy duck to fatty liver is an evolutionary by-product. In conclusion, this study revealed the potential mechanisms underlying the susceptibility of Muscovy duck to fatty liver.

Adiponectin: friend or foe in obesity and inflammation

Adiponectin is an adipokine predominantly produced by fat cells, circulates and exerts insulin-sensitizing, cardioprotective and anti-inflammatory effects. Dysregulation of adiponectin and/or adiponectin signaling is implicated in a number of metabolic diseases such as obesity, insulin resistance, diabetes, and cardiovascular diseases. However, while the insulin-sensitizing and cardioprotective effects of adiponectin have been widely appreciated in the field, the obesogenic and anti-inflammatory effects of adiponectin are still of much debate. Understanding the physiological function of adiponectin is critical for adiponectin-based therapeutics for the treatment of metabolic diseases.

Genetic determinants of metabolic biomarkers and their associations with cardiometabolic traits in Hispanic/Latino adolescents

BACKGROUND

Metabolic regulation plays a significant role in energy homeostasis, and adolescence is a crucial life stage for the development of cardiometabolic disease (CMD). This study aims to investigate the genetic determinants of metabolic biomarkers-adiponectin, leptin, ghrelin, and orexin-and their associations with CMD risk factors.

METHODS

We characterized the genetic determinants of the biomarkers among Hispanic/Latino adolescents of the Santiago Longitudinal Study (SLS) and identified the cumulative effects of genetic variants on adiponectin and leptin using biomarker polygenic risk scores (PRS). We further investigated the direct and indirect effect of the biomarker PRS on downstream body fat percent (BF%) and glycemic traits using structural equation modeling.

RESULTS

We identified putatively novel genetic variants associated with the metabolic biomarkers. A substantial amount of biomarker variance was explained by SLS-specific PRS, and the prediction was improved by including the putatively novel loci. Fasting blood insulin and insulin resistance were associated with PRS for adiponectin, leptin, and ghrelin, and BF% was associated with PRS for adiponectin and leptin. We found evidence of substantial mediation of these associations by the biomarker levels.

CONCLUSIONS

The genetic underpinnings of metabolic biomarkers can affect the early development of CMD, partly mediated by the biomarkers.

IMPACT

This study characterized the genetic underpinnings of four metabolic hormones and investigated their potential influence on adiposity and insulin biology among Hispanic/Latino adolescents. Fasting blood insulin and insulin resistance were associated with polygenic risk score (PRS) for adiponectin, leptin, and ghrelin, with evidence of some degree of mediation by the biomarker levels. Body fat percent (BF%) was also associated with PRS for adiponectin and leptin. This provides important insight on biological mechanisms underlying early metabolic dysfunction and reveals candidates for prevention efforts. Our findings also highlight the importance of ancestrally diverse populations to facilitate valid studies of the genetic architecture of metabolic biomarker levels.

Genetic variations in adiponectin levels and dietary patterns on metabolic health among children with normal weight versus obesity: the BCAMS study

BACKGROUND/OBJECTIVES

Adiponectin represents an important link between adipose tissue dysfunction and cardiometabolic risk in obesity; however, there is a lack of data on the effects of adiponectin-related genetic variations and gene-diet interactions on metabolic disorders in children. We aimed to investigate possible interactions between adiponectin-related genetic variants and habitual dietary patterns on metabolic health among children with normal weight versus overweight/obesity, and whether these effects in childhood longitudinally contribute to metabolic risk at follow-up.

SUBJECTS/METHODS

In total, 3,317 Chinese children aged 6-18 at baseline and 339 participants at 10-year follow-up from the Beijing Child and Adolescent Metabolic Syndrome study cohort were included. Baseline lifestyle factors, plasma adiponectin levels, and six adiponectin-related genetic variants resulting from GWAS in East Asians (loci in/near ADIPOQ, CDH13, WDR11FGF, CMIP, and PEPD) were assessed for their associations with the metabolic disorders. Being metabolically unhealthy was defined by exhibiting any metabolic syndrome component.

RESULTS

Among the six loci, ADIPOQ rs6773957 (OR 1.26, 95% CI:1.07-1.47, P = 0.004) and adiponectin receptor CDH13 rs4783244 (0.82, 0.69-0.96, P = 0.017) were correlated with metabolic risks independent of lifestyle factors in normal-weight children, but the associations were less obvious in those with overweight/obesity. A significant interaction between rs6773957 and diet (P_interaction = 0.004) for metabolic health was observed in normal-weight children. The adiponectin-decreasing allele of rs6773957 was associated with greater metabolic risks in individuals with unfavorable diet patterns (P < 0.001), but not in those with healthy patterns (P > 0.1). A similar interaction effect was observed using longitudinal data (P_interaction = 0.029).

CONCLUSIONS

These findings highlight a novel gene-diet interaction on the susceptibility to cardiometabolic disorders, which has a long-term impact from childhood onward, particularly in those with normal weight. Personalized dietary advice in these individuals may be recommended as an early possible therapeutic measure to improve metabolic health.

Association of CDH13 Gene Polymorphism and Metabolic Syndrome in Gambian Population

Background:

Polymorphism in CDH13 gene, which encodes for the adiponectin receptor, T-cadherin, is a genetic risk factor associated with metabolic syndrome. CDH13 rs3865188, which is found in the promoter region of the CDH13 gene, has been found to be associated with metabolic syndrome and its traits in Asian and European Caucasian populations. However, to the best of our knowledge, it was yet to be assessed in a Black African population.

Objective:

The aim of this study was to investigate the association of CHD13 rs3865188 and metabolic syndrome in a Gambian population.

Methods:

It was a genetic association study in a cross-sectional design in 136 Gambian participants. CDH13 rs3865188 was genotyped using PCR master mix and sequencing. Blood sugar, triglyceride and high-density lipoprotein levels were determined by standard clinical laboratory methods.

Results:

CDH13 rs3865188 was found to be significantly associated metabolic syndrome (p=0.034). Genotype AT appeared to be risk factor for metabolic syndrome (OR=2.41, 95% CI, 1.20–4.84, p=0.014). We found genotypes CC and CA in CHD13 rs3865188 for the first time.

Conclusion:

Our study demonstrated significant association between CDH13 rs385618 and metabolic syndrome in a Gambian population (Black African population for the first time). Individuals with genotype AT are at higher risk of developing metabolic syndrome.

Genome-Wide Association Study on Adiponectin-Mediated Suppression of HDL-C Levels in Taiwanese Individuals Identifies Functional Haplotypes in CDH13

CDH13 encodes T-cadherin, which is expressed in the vasculature and cardiac myocytes and is the receptor for hexameric and high-molecular-weight adiponectin. The CDH13 region is the most pivotal locus associated with adiponectin level. Mediation analysis is a method to explore the effect of a third variable, it is assumed that the magnitude of the relationship between the independent and dependent variables will be reduced by statistical adjustment for a third variable. In addition, mediation can further occur in the case when the mediator acts as a pathway-suppressor variable that means a suppression effect may be suggested if the statistical removal of a mediation effect could increase the magnitude of the relationship between the independent and dependent variables. Here, we aimed to explore the suppression effect in a genome-wide association study, and investigate possible mechanisms that may link adiponectin to CDH13 variants and high-density lipoprotein cholesterol (HDL-C). Genome-wide association data for adiponectin and HDL-C were accessible for 2349 Taiwan-biobank participants. The mediation analysis was conducted with the CDH13 lead single nucleotide polymorphism (SNP) rs4783244. The cloned constructs of CDH13 haplotypes (GG and TT) identified from the rs4783244 G/T and rs12051272 G/T SNPs were transiently expressed in HEK293T cells and investigated using the luciferase reporter assay. Genome-wide association analysis showed that HDL-C is significantly associated with variants in CDH13 after adjusting for the adiponectin level. The lead SNP rs4783244 was significantly associated with lower adiponectin levels and exhibited a suppression effect on HDL-C when adiponectin was included as a third factor in the mediation analysis. Luciferase reporter assay results further demonstrated that the GG haplotype increased enhancer activity, whereas the haplotype TT significantly reduced the activity of this enhancer. We present the first evidence of the suppressive role of adiponectin in the genome-wide association between CDH13 and HDL-C. CDH13 may increase the HDL-C levels, and its expression is suppressed by adiponectin.

T-Cadherin and the Ratio of Its Ligands as Predictors of Carotid Atherosclerosis: A Pilot Study

In the cardiovascular system, atherogenic low-density lipoproteins (LDL) and the protective hormone adiponectin bind to the same receptor, T-cadherin. In this study, we tested the hypothesis that the ratio of circulating LDL to high-molecular weight (HMW) adiponectin could predict the development of atherosclerosis. Using enzyme-linked immunosorbent assay, we measured the level of circulating HMW adiponectin in the blood of donors together with ultrasound measuring of intima-media thickness (IMT) of carotid arteries. Single-nucleotide polymorphisms in the T-cadherin gene were identified using polymerase chain reaction. We found that carotid artery IMT is inversely correlated with the level of HMW in male subjects. We also found that the G allele of rs12444338 SNP in the T-cadherin gene correlates with a lower level of circulating T-cadherin and thinner IMT and therefore could be considered as an atheroprotective genotype. Despite our data, we could not provide direct evidence for the initial study hypothesis. However, we did uncover an important correlation between circulating T-cadherin and thinner carotid IMT.

Ischemic Stroke and Sleep: The Linking Genetic Factors

This review summarizes the available data about genetic factors which can link ischemic stroke and sleep. Sleep patterns (subjective and objective measures) are characterized by heritability and comprise up to 38-46%. According to Mendelian randomization analysis, genetic liability for short sleep duration and frequent insomnia symptoms is associated with ischemic stroke (predominantly of large artery subtype). The potential genetic links include variants of circadian genes, genes encoding components of neurotransmitter systems, common cardiovascular risk factors, as well as specific genetic factors related to certain sleep disorders.

Role of Perivascular Adipose Tissue-Derived Adiponectin in Vascular Homeostasis

Studies of adipose tissue biology have demonstrated that adipose tissue should be considered as both passive, energy-storing tissue and an endocrine organ because of the secretion of adipose-specific factors, called adipokines. Adiponectin is a well-described homeostatic adipokine with metabolic properties. It regulates whole-body energy status through the induction of fatty acid oxidation and glucose uptake. Adiponectin also has anti-inflammatory and antidiabetic properties, making it an interesting subject of biomedical studies. Perivascular adipose tissue (PVAT) is a fat depot that is conterminous to the vascular wall and acts on it in a paracrine manner through adipokine secretion. PVAT-derived adiponectin can act on the vascular wall through endothelial cells and vascular smooth muscle cells. The present review describes adiponectin's structure, receptors, and main signaling pathways. We further discuss recent studies of the extent and nature of crosstalk between PVAT-derived adiponectin and endothelial cells, vascular smooth muscle cells, and atherosclerotic plaques. Furthermore, we argue whether adiponectin and its receptors may be considered putative therapeutic targets.

Circulating Adiponectin and Its Association with Metabolic Traits and Type 2 Diabetes: Gene-Diet Interactions Focusing on Selected Gene Variants and at the Genome-Wide Level in High-Cardiovascular Risk Mediterranean Subjects

Adiponectin is gaining renewed interest since, in addition to its possible protective role against insulin resistance and arteriosclerosis, recent studies suggest other additional favorable effects. However, the influence of gene-diet interactions on plasma adiponectin levels is still little understood. We analyzed the association between plasma adiponectin levels and various metabolic traits in a high-cardiovascular risk Mediterranean population, as well as the genetic effect of four candidate single-nucleotide polymorphisms (SNPs) in the adiponectin gene (ADIPOQ) and their interactions with the Mediterranean dietary pattern. Additionally, we explored, at the genome-wide level, the SNPs most associated with plasma adiponectin levels, as well as gene-diet interactions with the Mediterranean diet. In the 954 participants studied (aged 55-80 years), plasma adiponectin levels were strongly associated with plasma HDL-C concentrations (p = 6.6 × 10^-36) and inversely related to triglycerides (p = 4.7 × 10^-18), fasting glucose (p = 3.5 × 10^-16) and type 2 diabetes (p = 1.4 × 10^-7). Of the four pre-selected ADIPOQ candidate SNPs, the one most associated with plasma adiponectin was the -11391G > A (rs17300539) promoter SNP (p = 7.2 × 10^-5, in the multivariable adjusted model). No significant interactions with the Mediterranean diet pattern were observed for these SNPs. Additionally, in the exploratory genome-wide association study (GWAS), we found new SNPs associated with adiponectin concentrations at the suggestive genome-wide level (p < 1 × 10^-5) for the whole population, including the lead SNP rs9738548 (intergenic) and rs11647294 in the VAT1L (Vesicle Amine Transport 1 Like) gene. We also found other promising SNPs on exploring different strata such as men, women, diabetics and non-diabetics (p = 3.5 × 10^-8 for rs2850066). Similarly, we explored gene-Mediterranean diet interactions at the GWAS level and identified several SNPs with gene-diet interactions at p < 1 × 10^-5. A remarkable gene-diet interaction was revealed for the rs2917570 SNP in the OPCML (Opioid Binding Protein/Cell Adhesion Molecule Like) gene, previously reported to be associated with adiponectin levels in some populations. Our results suggest that, in this high-cardiovascular risk Mediterranean population, and even though adiponectin is favorably associated with metabolic traits and lower type 2 diabetes, the gene variants more associated with adiponectin may be population-specific, and some suggestive gene-Mediterranean diet interactions were detected.

Adipocyte-Endothelium Crosstalk in Obesity

Obesity is characterized by pathological adipose tissue (AT) expansion. While healthy AT expansion enhances systemic insulin sensitivity, unhealthy AT expansion through increased adipocyte size is associated with insulin resistance, fibrosis, hypoxia, and reduced adipose-derived adiponectin secretion. The mechanisms causing the unhealthy AT expansion are not fully elucidated; yet, dysregulated crosstalk between cells within the AT is an important contributor. Evidence from animal and human studies suggests a crucial role of the crosstalk between vascular endothelium (the innermost cell type in blood vessels) and adipocytes for metabolic homeostasis. Arterial endothelial cells are directly involved in maintaining normal organ functions through local blood flow regulation. The endothelial-dependent regulation of blood flow in AT is hampered in obesity, which negatively affects the adipocyte. Moreover, endothelial cells secrete extracellular vesicles (EVs) that target adipocytes in vivo. The endothelial EVs secretion is hampered in obesity and may be affected by the adipocyte-derived adipokine adiponectin. Adiponectin targets the vascular endothelium, eliciting organ-protective functions through binding to T-cadherin. The reduced obesity-induced adiponectin binding of T-cadherin reduces endothelial EV secretion. This affects endothelial health and cell-cell communication between AT cells and distant organs, influencing systemic energy homeostasis. This review focuses on the current understanding of endothelial and adipocyte crosstalk. We will discuss how obesity changes the AT environment and how these changes contribute to obesity-associated metabolic disease in humans. Particularly, we will describe and discuss the EV-dependent communication and regulation between adipocytes, adiponectin, and the endothelial cells regulating systemic energy homeostasis in health and metabolic disease in humans.

Exploring gene-gene interaction in family-based data with an unsupervised machine learning method: EPISFA

Gene-gene interaction (G × G) is thought to fill the gap between the estimated heritability of complex diseases and the limited genetic proportion explained by identified single-nucleotide polymorphisms. The current tools for exploring G × G were often developed for case-control designs with less considerations for their applications in families. Family-based studies are robust against bias led from population stratification in genetic studies and helpful in understanding G × G. We proposed a new algorithm epistasis sparse factor analysis (EPISFA) and epistasis sparse factor analysis for linkage disequilibrium (EPISFA-LD) based on unsupervised machine learning to screen G × G. Extensive simulations were performed to compare EPISFA/EPISFA-LD with a classical family-based algorithm FAM-MDR (family-based multifactor dimensionality reduction). The results showed that EPISFA/EPISFA-LD is a tool of both high power and computational efficiency that could be applied in family designs and is applicable within high-dimensionality datasets. Finally, we applied EPISFA/EPISFA-LD to a real dataset drawn from the Fangshan/family-based Ischemic Stroke Study in China. Five pairs of G × G were discovered by EPISFA/EPISFA-LD, including three pairs verified by other algorithms (FAM-MDR and logistic), and an additional two pairs uniquely identified by EPISFA/EPISFA-LD only. The results from EPISFA might offer new insights for understanding the genetic etiology of complex diseases. EPISFA/EPISFA-LD was implemented in R. All relevant source code as well as simulated data could be freely downloaded from https://github.com/doublexism/episfa.

Differential Proteomic Expression of Equine Cardiac and Lamellar Tissue During Insulin-Induced Laminitis

Endocrinopathic laminitis is pathologically similar to the multi-organ dysfunction and peripheral neuropathy found in human patients with metabolic syndrome. Similarly, endocrinopathic laminitis has been shown to partially result from vascular dysfunction. However, despite extensive research, the pathogenesis of this disease is not well elucidated and laminitis remains without an effective treatment. Here, we sought to identify novel proteins and pathways underlying the development of equine endocrinopathic laminitis. Healthy Standardbred horses (n = 4/group) were either given an electrolyte infusion, or a 48-h euglycemic-hyperinsulinemic clamp. Cardiac and lamellar tissues were analyzed by mass spectrometry (FDR = 0.05). All hyperinsulinemic horses developed laminitis despite being previously healthy. We identified 514 and 709 unique proteins in the cardiac and lamellar proteomes, respectively. In the lamellar tissue, we identified 14 proteins for which their abundance was significantly increased and 13 proteins which were significantly decreased in the hyperinsulinemic group as compared to controls. These results were confirmed via real-time reverse-transcriptase PCR. A STRING analysis of protein-protein interactions revealed that these increased proteins were primarily involved in coagulation and complement cascades, platelet activity, and ribosomal function, while decreased proteins were involved in focal adhesions, spliceosomes, and cell-cell matrices. Novel significant differentially expressed proteins associated with hyperinsulinemia-induced laminitis include talin−1, vinculin, cadherin-13, fibrinogen, alpha-2-macroglobulin, and heat shock protein 90. In contrast, no proteins were found to be significantly differentially expressed in the heart of hyperinsulinemic horses compared to controls. Together, these data indicate that while hyperinsulinemia induced, in part, microvascular damage, complement activation, and ribosomal dysfunction in the lamellae, a similar effect was not seen in the heart. In brief, this proteomic investigation of a unique equine model of hyperinsulinemia identified novel proteins and signaling pathways, which may lead to the discovery of molecular biomarkers and/or therapeutic targets for endocrinopathic laminitis.

Interorgan communication by exosomes, adipose tissue, and adiponectin in metabolic syndrome

Adipose tissue plays important roles in regulating whole-body energy metabolism through its storage function in white adipocytes and its dissipating function in brown and beige adipocytes. Adipose tissue also produces a variety of secreted factors called adipocytokines, including leptin and adiponectin. Furthermore, recent studies have suggested the important roles of extracellular vesicles of endosomal origin termed exosomes, which are secreted from adipocytes and other cells in adipose tissue and influence whole-body glucose and lipid metabolism. Adiponectin is known to be a pleiotropic organ-protective protein that is exclusively produced by adipocytes and decreased in obesity. Adiponectin accumulates in tissues such as heart, muscle, and vascular endothelium through binding with T-cadherin, a glycosylphosphatidylinositol-anchored (GPI-anchored) cadherin. Recently, adiponectin was found to enhance exosome biogenesis and secretion, leading to a decrease in cellular ceramides, excess of which is known to cause insulin resistance and cardiovascular disease phenotypes. These findings support the hypothesis that adipose tissue metabolism systemically regulates exosome production and whole-body metabolism through exosomes. This review focuses on intra-adipose and interorgan communication by exosomes, adiponectin-stimulated exosome production, and their dysregulation in metabolic diseases.

Genetic variation, adipokines, and cardiometabolic disease

Adipokines are adipocyte-secreted cell signalling proteins that travel to distant target organs and tissues, where they regulate a variety of biological actions implicated in cardiometabolic health. In the past decade, genome-wide association studies have identified multiple genetic variants associated with circulating levels of adipokines, providing new instruments for examining the role of adipokines in cardiometabolic pathologies. Currently, there is limited genetic evidence of causal relationships between adipokines and cardiometabolic disease, which is consistent with findings from randomized clinical trials that have thus far shown limited success for adipokine-based treatments in improving cardiometabolic health. Incorporating human genetic data in early phases of target selection is essential for enhancing the success of adipokine-based therapies for cardiometabolic disease.

Genome-wide association study of genetic variants related to anthracycline-induced cardiotoxicity in early breast cancer

We performed a genome‐wide association study to investigate the association between single nucleotide polymorphisms and anthracycline‐induced cardiotoxicity (ACT) in patients diagnosed with early breast cancer. From January 2000 to December 2015, 8490 patients underwent breast surgery at the National Cancer Center in Korea. Patients who received doxorubicin (cumulative dose 240 mg/m²‐300 mg/m²) with or without trastuzumab as a neoadjuvant/adjuvant therapy were included in our cohort. Sixty‐seven patients in our cohort were diagnosed with ACT. Clinical data, including age, body weight, height, cancer stage, trastuzumab treatment, comorbidities, and concomitant medications, were collected retrospectively. Patients were classified as having either persistent or transient ACT based on their clinical course. In total, 346 946 single nucleotide polymorphisms in 42 cases and 215 controls were tested in this study. Body mass index (BMI) ≥25 kg/m² [odds ratio (OR) = 2.45, 95% confidence interval (CI), 1.23‐4.88, P = .011] and trastuzumab use (OR = 2.40, 95% CI, 1.11‐5.17, P = .026) were identified as significant risk factors. We found 7 genetic variants for ACT including rs17530621 (SHISA3, P = 3.10E−06), rs11894115 (MPP4, P = 4.71E−06), rs58328254 (RPL7, P = 6.09E−06), and rs117299725 (PRUNE2, P = 8.53E−06), although none of these variants reached the Bonferroni‐corrected significance level when adjusted for BMI and trastuzumab use ( = α1.44E−07 based on 0.05/346 946). rs117299725 was a common variant when only the persistent ACT group was analyzed separately. It is meaningful that our study analyzed comprehensively the influence of genetic variation on ACT, along with some clinical factors in Asian breast cancer patients who received anthracycline with or without trastuzumab. Further research will be needed on candidate genetic variants found in this study.

Effects of Adiponectin on T2DM and Glucose Homeostasis: A Mendelian Randomization Study

PURPOSE

The associations of adiponectin with type 2 diabetes mellitus (T2DM), glucose homeostasis (including β-cell function index (HOMA-β), insulin resistance (HOMA-IR), fasting insulin (FI) and fasting glucose (FG)) have reported in epidemiological studies. However, the previous observational studies are prone to biases, such as reverse causation and residual confounding factors. Herein, a Mendelian Randomization (MR) study was conducted to determine whether causal effects exist among them.

MATERIALS AND AND METHODS

Two-sample MR analyses and multiple sensitivity analyses were performed using the summary data from the ADIPOGen consortium, MAGIC Consortium, and a meta-analysis of GWAS with a considerable sample of T2DM (62,892 cases and 596,424 controls of European ancestry). We got eight valid genetic variants to predict the causal effect among adiponectin and T2DM and glucose homeostasis after excluding the probable invalid or pleiotropic variants.

RESULTS

Adiponectin was not associated with T2DM (odds ratio (OR) = 1.004; 95% confidence interval (CI): 0.740, 1.363) when using MR Egger after removing the invalid SNPs, and the results were consistent when using the other four methods. Similar results existed among adiponectin and HOMA-β, HOMA-IR, FI, FG.

CONCLUSION

Our MR study revealed that adiponectin had no causal effect on T2DM and glucose homeostasis and that the associations among them in observational studies may be due to confounding factors.

A potential role for the CDH13/CDH15 gene in repeat revascularization after first percutaneous coronary intervention

Aim: Major drawbacks of percutaneous coronary intervention are the high occurrence of repeat revascularization due to restenosis and disease progression. The aim of this study was to find genetic indicators to predict the risk of repeat revascularization. Materials & methods: From April 2015 to June 2016, 143 patients with percutaneous coronary intervention with genetic test results were enrolled. SNPs were measured by OmniZhongHua-8, and the SNPs in pathways genes related to known stenosis-related processes from the KEGG, BioCarta and Gene Cards databases were selected for analysis. Results: Cell-extracellular matrix interactions were the pathways with the most significant SNP (CDH15 rs72819363) association with repeat revascularization. Compared with CDH13 rs11859453G carriers, the adjusted odds ratio for A carriers was 0.25 and 0.33 at 18 and 30 months. Conclusion: We demonstrated a potential role of the cell-extracellular matrix interactions pathway and the possible biomarker CDH13/CDH15 in the development of coronary repeat revascularization.

Adiponectin, a unique adipocyte-derived factor beyond hormones

Visceral fat accumulation has a marked impact on atherosclerotic cardiovascular diseases and metabolic syndrome clustering diabetes, dyslipidemia, and hypertension. Adiponectin, an adipocyte-derived circulating protein, is a representative adipocytokine and uniquely possesses two major properties: 1) its circulating concentration is approximately 3-6 orders of magnitude greater than ordinary hormones and cytokines; 2) its concentration inversely correlates with body fat mass despite its adipocyte-specific production. Low serum levels of adiponectin correlate with cardiometabolic diseases. Extensive experimental evidence has demonstrated that adiponectin possesses multiple properties, such as anti-atherosclerotic, anti-diabetic, and anti-inflammatory activities. It has been shown to play a central role against the development of metabolic syndrome and its complications. However, even approximately 25 years after its discovery, the properties of adiponectin, including how and why it exerts multiple beneficial effects on various tissues and/or organs, remain unclear. Furthermore, the mechanisms responsible for the very high circulating concentrations of adiponectin in the bloodstream have not been elucidated. Several adiponectin-binding partners, such as AdipoR1/2, have been identified, but do not fully explain the multi-functional and beneficial properties of adiponectin. Recent advances in adiponectin research may resolve these issues. Adiponectin binds to and covers cell surfaces with T-cadherin, a unique glycosylphosphatidylinositol (GPI)-anchored cadherin. The adiponectin/T-cadherin complex enhances exosomal production and release, excreting cell-toxic products from cells, particularly in the vasculature. In this review, we discuss adiponectin and the role of the adiponectin/T-cadherin system in the maintenance of whole body homeostasis and cardiovascular protection.

Native adiponectin in serum binds to mammalian cells expressing T-cadherin, but not AdipoRs or calreticulin

Adiponectin is an adipocyte-derived atypically abundant circulating factor that protects various organs and tissues through its receptors, AdipoRs, calreticulin, and T-cadherin. To identify the major binding partner of circulating native adiponectin, we expressed these receptors on the surface of HEK293 cells. Adiponectin, either that in mouse or human serum, purified from serum, or produced by mammalian cells, bound to cells expressing T-cadherin, but not to those expressing AdipoR1 or calreticulin. The stable introduction of T-cadherin and AdipoR1 into CHO cells resulted in the cell surface localization of these receptors. Native adiponectin in serum bound to cells expressing T-cadherin, not to those expressing AdipoR1. The knockdown of T-cadherin, but not AdipoRs resulted in the significant attenuation of native adiponectin binding to C2C12 myotubes. Therefore, native adiponectin binding depended on the amount of T-cadherin expressed in HEK293 cells, CHO cells, and C2C12 myotubes. Collectively, our mammalian cell-based studies suggest that T-cadherin is the major binding partner of native adiponectin in serum.

Insulin and adipokine signaling and their cross-regulation in postmortem human brain

Aberrant insulin and adipokine signaling has been implicated in cognitive decline associated with both type 2 diabetes mellitus and neurodegenerative diseases. We established methods that reliably measure insulin, adiponectin and leptin signaling, and their crosstalk, in thawed postmortem mid-frontal cortical tissue from cognitively normal older subjects with a short postmortem interval. Insulin-evoked insulin receptor (IR) activation increases activated, tyrosine-phosphorylated IRβ on tyrosine residues 960, 1150, and 1151, insulin receptor substrate-1 recruitment to IRβ and phosphorylated RAC-α-serine/threonine-protein kinase. Adiponectin augments, but leptin inhibits, insulin signaling. Adiponectin activates adiponectin receptors to induce APPL1 binding to adiponectin receptor 1 and 2 and T-cadherin and downstream adenosine monophosphate-dependent protein kinase phosphorylation. Insulin inhibited adiponectin-induced signaling. In addition, leptin-induced leptin receptor (OB-R) signaling promotes Janus kinase 2 recruitment to OB-R and Janus kinase 2 and downstream signal transducer and activator of transcription 3 phosphorylation. Insulin enhanced leptin signaling. These data demonstrate insulin and adipokine signaling interactions in human brain. Future studies can use these methods to examine insulin, adiponectin, and leptin metabolic dysregulation in aging and disease states, such as type 2 diabetes and Alzheimer's disease-related dementias.

The pleiotropic effect of rs7903146 on type 2 diabetes and ischemic stroke: a family-based study in a Chinese population

The rs7903146, an established genetic variant susceptible to type 2 diabetes (T2D), is also reported to be related to ischemic stroke (IS), though conflicting. Furthermore, it remained unknown whether the genetic association with stroke is independent of T2D. In the current study, 1603 individuals across 986 families were included. The genetic pleiotropic effect on each outcome diseases (T2D, overall IS, or each subtype) was assessed using multilevel logistic regression after adjustment for multiple covariates. Principal component of heritability (PCH) was also used to assess the pleiotropy by combining T2D and IS into one outcome for analysis. To identify the T2D-independent path out of the pleiotropic effect on IS, T2D status was additionally adjusted for the risk of IS or each subtype. The analyses of putative molecular pathways (dyslipidemia, hypertension, obesity and inflammation) and gene-lifestyle interactions were also performed. We found that rs7903146_T allele was associated with a 77% higher risk of T2D, 55% of IS, and 70% of large artery atherosclerosis (LAA) subtype respectively. Particularly, a T2D-independent genetic effect was identified to increase the risk of overall IS and LAA. No evidence on the molecular mechanisms and gene-lifestyle interaction behind the pleiotropic genetic effect was observed. In conclusion, our study provided evidence that a T2D-independent path was identified out of the pleiotropic effect of rs7903146 on IS. However, further studies were needed to validate the biological mechanisms behind the pleiotropic effect and the modification by lifestyle intervention.

Adiponectin promotes muscle regeneration through binding to T-cadherin

Skeletal muscle has remarkable regenerative potential and its decline with aging is suggested to be one of the important causes of loss of muscle mass and quality of life in elderly adults. Metabolic abnormalities such as obesity were linked with decline of muscle regeneration. On the other hand, plasma levels of adiponectin are decreased in such metabolic conditions. However, plasma levels of adiponectin have been shown to inversely correlate with muscle mass and strength in elderly people especially with chronic heart failure (CHF). Here we have addressed whether adiponectin has some impact on muscle regeneration after cardiotoxin-induced muscle injury in mice. Muscle regeneration was delayed by angiotensin II infusion, mimicking aging and CHF as reported. Adiponectin overexpression in vivo decreased necrotic region and increased regenerating myofibers. Such enhanced regeneration by excess adiponectin was also observed in adiponectin null mice, but not in T-cadherin null mice. Mechanistically, adiponectin accumulated on plasma membrane of myofibers both in mice and human, and intracellularly colocalized with endosomes positive for a multivesicular bodies/exosomes marker CD63 in regenerating myofibers. Purified high-molecular multimeric adiponectin similarly accumulated intracellularly and colocalized with CD63-positive endosomes and enhanced exosome secretion in differentiating C2C12 myotubes but not in undifferentiated myoblasts. Knockdown of T-cadherin in differentiating C2C12 myotubes attenuated both adiponectin-accumulation and adiponectin-mediated exosome production. Collectively, our studies have firstly demonstrated that adiponectin stimulates muscle regeneration through T-cadherin, where intracellular accumulation and exosome-mediated process of adiponectin may have some roles.

Adipokines and Aging: Findings From Centenarians and the Very Old

Adipose tissue, which was once considered as a simple energy storage depot, is now recognized as an active endocrine organ that regulates the whole-body energy homeostasis by secreting hundreds of bioactive substances termed adipokines. Dysregulation of adipokines is a key feature of insulin resistance and a metabolic syndrome associated with obesity. Adipokine dysregulation and insulin resistance are also associated with energy-deprivation conditions, such as frailty in old age. Previous studies have demonstrated that preserved insulin sensitivity and low prevalence of diabetes are the metabolic peculiarities of centenarians, suggesting the possible role of adipokine homeostasis in healthy longevity. Among the numerous adipokines, adiponectin is regarded as unique and salutary, showing negative correlations with several age- and obesity-related metabolic disturbances and a positive correlation with longevity and insulin sensitivity among centenarians. However, large-scale epidemiological studies have implied the opposite aspect of this adipokine as a prognostic factor for all-cause and cardiovascular mortality in patients with heart failure or kidney disease. In this review, the clinical significance of adiponectin was comparatively addressed in centenarians and the very old, in terms of frailty, cardiovascular risk, and mortality.

CDH13 promoter methylation regulates cisplatin resistance of non-small cell lung cancer cells

Reversing cisplatin resistance of lung cancer cell line A549/DDP through recovering cadherin 13 (CDH13) expression by demethylation was investigated in the current study. RT-PCR was used to measure CDH13 expression in lung cancer A549 and A549/DDP cells with or without 5-Aza-CdR intervention. Methylation-specific PCR was used to detect CDH13 methylation. MTT assay and flow cytometry were used to measure the effects of cisplatin on inhibiting cell proliferation, apoptosis, and the reversal of cisplatin resistance. The IC₅₀ value of cisplatin for A549 and A549/DDP cells was 3.278±0.532 and 28.341±1.435 µmol/l, respectively (P<0.05). The cisplatin-resistance index of A549/DDP cells was up to 8.65. After 2.5, 10, or 40 µmol/l 5-Aza-CdR treatment, the apoptotic rates of A549/DDP cells were 9.4±0.86, 18.1±1.42 and 42±2.01%, respectively, which were significantly different to those of the control group (P<0.05). Methylation-specific PCR detected both methylation (M) and unmethylation (U) bands at CDH13 promoter region before 5-Aza-CdR intervention while it only detected an unmethylation band after the treatment with a higher concentration of 5-Aza-CdR, which indicates the transformation to unmethylation state. When 10 µmol/l 5-Aza-CdR was added, the IC₅₀ of cisplatin to A549/DDP cells was 8.472±0.415 µmol/l, and cisplatin resistance was reversed by 3.35-fold. CDH13 methylation is related to the cisplatin resistance of A549/DDP cells. 5-Aza-CdR can inhibit CDH13 methylation and recover CDH13 expression. With the increase in 5-Aza-CdR concentration, the unmethylation state of CDH13 is enhanced, which can strengthen the function of cisplatin inhibiting proliferation and apoptosis in A549/DDP cells.

Role of Adiponectin in Central Nervous System Disorders

Adiponectin, the most abundant plasma adipokine, plays an important role in the regulation of glucose and lipid metabolism. Adiponectin also possesses insulin-sensitizing, anti-inflammatory, angiogenic, and vasodilatory properties which may influence central nervous system (CNS) disorders. Although initially not thought to cross the blood-brain barrier, adiponectin enters the brain through peripheral circulation. In the brain, adiponectin signaling through its receptors, AdipoR1 and AdipoR2, directly influences important brain functions such as energy homeostasis, hippocampal neurogenesis, and synaptic plasticity. Overall, based on its central and peripheral actions, recent evidence indicates that adiponectin has neuroprotective, antiatherogenic, and antidepressant effects. However, these findings are not without controversy as human observational studies report differing correlations between plasma adiponectin levels and incidence of CNS disorders. Despite these controversies, adiponectin is gaining attention as a potential therapeutic target for diverse CNS disorders, such as stroke, Alzheimer's disease, anxiety, and depression. Evidence regarding the emerging role for adiponectin in these disorders is discussed in the current review.

T-cadherin gene variants are associated with nephropathy in subjects with type 1 diabetes

Background

High plasma adiponectin levels are associated with diabetic nephropathy (DN). T-cadherin gene (CDH13) variants have been shown to be associated with adiponectin levels. We investigated associations between allelic variations of CDH13 and DN in subjects with type 1 diabetes.

Methods

Two CDH13 polymorphisms were analysed in 1297 Caucasian subjects with type 1 diabetes from the 'Survival Genetic Nephropathy' (SURGENE) (n = 340, 10-year follow-up), 'Genesis France-Belgium' (GENESIS) (n = 501, 5-year follow-up for n = 462) and 'Génétique de la Néphropathie Diabétique' (GENEDIAB) (n = 456, 9-year follow-up for n = 283) cohorts. Adiponectin levels were measured in plasma samples from GENESIS and GENEDIAB cohorts.

Results

Pooled analysis of GENEDIAB and GENESIS studies showed that baseline plasma adiponectin levels were higher in subjects with established/advanced DN at inclusion (P < 0.0001) and in subjects who developed end-stage renal disease (ESRD) at follow-up (P < 0.0001). The minor allele of rs3865188 was associated with lower adiponectin levels (P = 0.006). rs11646213 [odds ratio (OR) 1.47; 95% confidence interval (CI) 1.18-1.85; P = 0.0009] and rs3865188 (OR 0.71; 95% CI 0.57-0.90; P = 0.004) were associated with baseline prevalence of established/advanced DN. These polymorphisms were also associated with the risk of ESRD (0.006 < P < 0.03). The association between rs11646213 (but not rs3865188) and renal function remained significant after adjustment for plasma adiponectin. In SURGENE, rs11646213 [hazard ratio (HR) 1.69; 95% CI 1.01-2.71; P = 0.04] and rs3865188 (HR 0.74; 95% CI 0.55-0.99; P = 0.04) were associated with risk of renal events (defined as progression to more severe DN stages).

Conclusions

Plasma adiponectin levels are associated with the prevalence of DN and the incidence of ESRD in patients with type 1 diabetes. CDH13 polymorphisms are also associated with the prevalence and incidence of DN, and with the incidence of ESRD in these patients. The association between CDH13 and DN may be due to pleiotropic effects, both dependent and independent of plasma adiponectin levels.

Loss of Cardio-Protective Effects at the CDH13 Locus Due to Gene-Sleep Interaction: The BCAMS Study

Left ventricular mass index (LVMI) provides a metric for cardiovascular disease risk. We aimed to assess the association of adiponectin-related genetic variants resulting from GWAS in East Asians (loci in/near CDH13, ADIPOQ, WDR11FGF, CMIP and PEPD) with LVMI, and to examine whether sleep duration modified these genetic associations in youth. The 559 subjects aged 15–28 years were recruited from the Beijing Child and Adolescent Metabolic Syndrome study. Among the six loci, CDH13 rs4783244 was significantly correlated with adiponectin levels (p = 8.07 × 10⁻⁷). The adiponectin-rising allele in rs4783244 locus was significantly associated with decreased LVMI (p = 6.99 × 10⁻⁴) after adjusting for classical cardiovascular risk factors, and further for adiponectin levels, while no significant association was found between the other loci and LVMI. Moreover, we observed a significant interaction effect between rs4783244 and sleep duration (p = .005) for LVMI; the genetic association was more evident in long sleep duration while lost in short sleep duration. Similar interaction was found in the subgroup analysis using longitudinal data (p = .025 for interaction). In this young Chinese population, CDH13 rs4783244 represents a key locus for cardiac structure, and confers stronger cardio-protection in longer sleep duration when contrasted with short sleep duration.

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CDH13 rs4783244 represents a key locus for cardiac structure.

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The effect of CDH13 rs4783244 on reduced left ventricular mass index is significantly modified by sleep duration.

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Short sleep may contribute to the loss of CDH13 locus-mediated cardio-protective effects.

We analyzed the associations of five adiponectin-associated genetic variants with left-ventricular mass index (LVMI), a cardiovascular risk factor, in a population of 559 youth. We found a significant protective association of CDH13 rs4783244 with decreased LVMI, independent of adiponectin and other conventional risk factors. Sleep duration has previously been described as a risk factor for increased LVMI in this population, therefore, we assessed modification of this association in CDH13 by sleep duration, and found that short sleep attenuated the cardio-protective effect of this SNP. Our study provides important insights into pathologic mechanisms and prevention strategies for early risk of cardiovascular disease.

The role of mineralocorticoid receptor signaling in the cross-talk between adipose tissue and the vascular wall

Vascular dysfunction and impaired endothelial mediated relaxation are powerful underlying abnormalities in the pathogenesis of hypertension, coronary heart disease, and stroke. Obesity, type 2 diabetes mellitus, and other metabolic abnormalities are associated with activation of mineralocorticoid receptor (MRs) in the vasculature and adipose tissue. While MR signaling is involved in the normal physiological differentiation and maturation of adipocyte, enhanced activation of MRs also contributes to increase oxidative stress, release of pro-inflammatory adipokines, and dysregulation of adipocyte autophagy. This, in turn, increases the maladaptive expansion of subcutaneous, visceral and perivascular adipose tissue, resulting in systemic and cardiovascular (CV) insulin resistance and increased CV stiffness and impaired vascular and cardiac relaxation. This review summarizes the normal role of MR activation in adipose tissues and explores the mechanisms by which excessive MR activation mediates adipose tissue inflammation and vascular dysfunction. Potential preventative and therapeutic strategies directed in the prevention of MR activation and CV disease are also discussed.

Adiponectin/T-cadherin system enhances exosome biogenesis and decreases cellular ceramides by exosomal release

Adiponectin, an adipocyte-derived circulating protein, accumulates in vasculature, heart, and skeletal muscles through interaction with a unique glycosylphosphatidylinositol-anchored cadherin, T-cadherin. Recent studies have demonstrated that such accumulation is essential for adiponectin-mediated cardiovascular protection. Here, we demonstrate that the adiponectin/T-cadherin system enhances exosome biogenesis and secretion, leading to the decrease of cellular ceramides. Adiponectin accumulated inside multivesicular bodies, the site of exosome generation, in cultured cells and in vivo aorta, and also in exosomes in conditioned media and in blood, together with T-cadherin. The systemic level of exosomes in blood was significantly affected by adiponectin or T-cadherin in vivo. Adiponectin increased exosome biogenesis from the cells, dependently on T-cadherin, but not on AdipoR1 or AdipoR2. Such enhancement of exosome release accompanied the reduction of cellular ceramides through ceramide efflux in exosomes. Consistently, the ceramide reduction by adiponectin was found in aortas of WT mice treated with angiotensin II, but not in T-cadherin-knockout mice. Our findings provide insights into adiponectin/T-cadherin-mediated organ protection through exosome biogenesis and secretion.

Adiponectin Single Nucleotide Polymorphisms and Serum Levels Are Relevant to Prognosis of Patients With Aneurysmal Subarachnoid Hemorrhages

To investigate the association of adiponectin gene polymorphisms and its levels with aneurysmal subarachnoid hemorrhages (aSAHs) prognosis. This case-control study enrolled 138 patients with aSAH and 102 healthy controls as case group and control group, respectively. Prognosis of case group was evaluated using Glasgow Outcome Scale. Polymerase chain reaction-restriction fragment length polymorphism was used to examine the genotypes of 45T>G and -11377C>G. Enzyme-linked immunosorbent assay was used to detect adiponectin levels. Logistic regression analysis was applied to assess the association of adiponectin gene polymorphism with aSAH prognosis. Case group had increased GG genotype and G allele genotype frequencies of 45T>G and -11377C>G compared with control group (all P < 0.01). In case group, TT genotype had the highest adiponectin level compared with both TG and GC genotypes (both P < 0.05). As for -11377C>G, GG genotype had the lowest adiponectin levels, followed by CG genotype and CC genotype in both groups (P < 0.05). In general, case group had decreased adiponectin levels compared with control group (P < 0.05). Univariate analysis showed that hypertension, Hunt-Hess grade, aneurysm size, aneurysms multiplicity and -11377C>G were associated with aSAH prognosis, while multivariate logistic regression analysis confirmed that hypertension, Hunt-Hess grade, residual flow in aneurysms and aneurysm size were independent risk factors for aSAH prognosis. Decreased adiponectin levels may be a pathological index for aSAH, which may be explain by the G allele of -11377C>G in adiponectin. Moreover, hypertension, Hunt-Hess grade, residual flow in aneurysms and aneurysm size may be independent risk factors for aSAH prognosis.

CDH13 abundance interferes with adipocyte differentiation and is a novel biomarker for adipose tissue health

BACKGROUND

CDH13, an atypical member of the cadherin superfamily, has been identified in adipocyte secretomes of lean mouse models. CDH13 abundance differs in mouse models according to their susceptibility to develop metabolic disorders, but the role of CDH13 in adipose tissue is unknown.

METHODS

Secreted CDH13 protein levels and mRNA levels in visceral adipose tissue were determined in lean and obese mouse models. In vitro studies were performed in 3T3-L1 adipocytes to determine the role of CDH13 in adipocyte differentiation. The pathophysiological impact of visceral adipose tissue CDH13 mRNA and circulating CDH13 levels were determined in humans (normal-weight men n = 37, obese men n = 109 including n = 51 type 2 diabetes patients) and in obese patients (n = 14) pre- and post-metabolic surgery.

RESULTS

This study shows that in visceral adipose tissue CDH13 protein secretion and mRNA levels were decreased in obese mouse models. Mechanistically, CDH13 affects lipid metabolism during adipogenesis but not in mature adipocytes. CDH13 knockdown during adipogenesis reduced fatty acid uptake and lipid content in developing adipocytes. Furthermore, CDH13 depletion during adipogenesis lowered the induction of PPARγ and C/EBPα expression. These observations are of pathophysiological impact since visceral adipose tissue CDH13 mRNA and circulating CDH13 levels were decreased in obese men compared to normal-weight controls. Weight loss induced by bariatric surgery restored circulating CDH13 to levels found in normal-weight controls.

CONCLUSIONS

CDH13 levels in adipose tissue and the circulation are affected by obesity in mouse models and humans and are restored by weight loss in humans. CDH13 interferes with the differentiation potential of adipocytes and therefore is a marker for plasticity of fat tissue that might reflect the health status of adipose tissue.

Genetic variation in CDH13 gene was associated with non-small cell lung cancer (NSCLC): A population-based case-control study

Cadherin 13 (CDH13, T-cadherin, H-cadherin) has been identified as an anti-oncogene in various cancers. Recent studies have reported that downregulation of H-cadherin in cancers is associated with CDH13 promoter hypermethylation, which could be affected by the single nucleotide polymorphisms (SNPs) near CpG sites in the CDH13 promoter. In the current study, we investigated and analyzed the association of seven SNPs (rs11646213, rs12596316, rs3865188, rs12444338, rs4783244, rs12051272 and rs7195409) with non-small cell lung cancer (NSCLC) using logistic regression analysis. SNPs rs11646213, rs12596316, rs3865188 and rs12444338 are located in the promoter region, rs4783244 and rs12051272 are located in intron 1, and rs7195409 is located in intron 7. A total of 454 patients with NSCLC were placed into a NSCLC group and 444 healthy controls were placed into a control group, all participants were recruited to genotype the SNPs using Taqman assay. Our results showed that the allelic frequencies of rs11646213 were significantly different between NSCLC and control groups (P = 0.006). In addition, the association analysis of these SNPs stratified into NSCLC pathologic stages I+II and III+IV showed that the allelic frequencies rs7195409 had a significant difference between NSCLC pathologic stages I+II and III+IV (P = 0.006). Our results indicated that the rs11646213 and rs7195409 in CDH13 could be associated with NSCLC or its pathologic stages in the Chinese Han population.

Genetic analysis in UK Biobank links insulin resistance and transendothelial migration pathways to coronary artery disease

UK Biobank is among the world's largest repositories for phenotypic and genotypic information in individuals of European ancestry. We performed a genome-wide association study in UK Biobank testing ∼9 million DNA sequence variants for association with coronary artery disease (4,831 cases and 115,455 controls) and carried out meta-analysis with previously published results. We identified 15 new loci, bringing the total number of loci associated with coronary artery disease to 95 at the time of analysis. Phenome-wide association scanning showed that CCDC92 likely affects coronary artery disease through insulin resistance pathways, whereas experimental analysis suggests that ARHGEF26 influences the transendothelial migration of leukocytes.

The unique prodomain of T-cadherin plays a key role in adiponectin binding with the essential extracellular cadherin repeats 1 and 2

Adiponectin, an adipocyte-derived circulating protein, accumulates in the heart, vascular endothelium, and skeletal muscles through an interaction with T-cadherin (T-cad), a unique glycosylphosphatidylinositol-anchored cadherin. Recent studies have suggested that this interaction is essential for adiponectin-mediated cardiovascular protection. However, the precise protein-protein interaction between adiponectin and T-cad remains poorly characterized. Using ELISA-based and surface plasmon analyses, we report here that T-cad fused with IgG Fc as a fusion tag by replacing its glycosylphosphatidylinositol-anchor specifically bound both hexameric and larger multimeric adiponectin with a dissociation constant of ∼1.0 nm and without any contribution from other cellular or serum factors. The extracellular T-cad repeats 1 and 2 were critical for the observed adiponectin binding, which is required for classical cadherin-mediated cell-to-cell adhesion. Moreover, the 130-kDa prodomain-bearing T-cad, uniquely expressed on the cell surface among members of the cadherin family and predominantly increased by adiponectin, contributed significantly to adiponectin binding. Inhibition of prodomain-processing by a prohormone convertase inhibitor increased 130-kDa T-cad levels and also enhanced adiponectin binding to endothelial cells both by more preferential cell-surface localization and by higher adiponectin-binding affinity of 130-kDa T-cad relative to 100-kDa T-cad. The preferential cell-surface localization of 130-kDa T-cad relative to 100-kDa T-cad was also observed in normal mice aorta in vivo In conclusion, our study shows that a unique key feature of the T-cad prodomain is its involvement in binding of the T-cad repeats 1 and 2 to adiponectin and also demonstrates that adiponectin positively regulates T-cad abundance.

Vascular transcriptome profiling identifies Sphingosine kinase 1 as a modulator of angiotensin II-induced vascular dysfunction

Vascular dysfunction is an important phenomenon in hypertension. We hypothesized that angiotensin II (AngII) affects transcriptome in the vasculature in a region-specific manner, which may help to identify genes related to vascular dysfunction in AngII-induced hypertension. Mesenteric artery and aortic transcriptome was profiled using Illumina WG-6v2.0 chip in control and AngII infused (490 ng/kg/min) hypertensive mice. Gene set enrichment and leading edge analyses identified Sphingosine kinase 1 (Sphk1) in the highest number of pathways affected by AngII. Sphk1 mRNA, protein and activity were up-regulated in the hypertensive vasculature. Chronic sphingosine-1-phosphate (S1P) infusion resulted in a development of significantly increased vasoconstriction and endothelial dysfunction. AngII-induced hypertension was blunted in Sphk1^-/- mice (systolic BP 167 ± 4.2 vs. 180 ± 3.3 mmHg, p < 0.05), which was associated with decreased aortic and mesenteric vasoconstriction in hypertensive Sphk1^-/- mice. Pharmacological inhibition of S1P synthesis reduced vasoconstriction of mesenteric arteries. While Sphk1 is important in mediating vasoconstriction in hypertension, Sphk1^-/- mice were characterized by enhanced endothelial dysfunction, suggesting a local protective role of Sphk1 in the endothelium. S1P serum level in humans was correlated with endothelial function (arterial tonometry). Thus, vascular transcriptome analysis shows that S1P pathway is critical in the regulation of vascular function in AngII-induced hypertension, although Sphk1 may have opposing roles in the regulation of vasoconstriction and endothelium-dependent vasorelaxation.

Associations between polymorphisms of the ADIPOQ gene and hypertension risk: a systematic and meta-analysis

ADIPOQ gene polymorphisms have been indicated to be associated with hypertension; however, published studies have reported inconsistent results. Eligible studies were retrieved by searching the PubMed, Embase and China National Knowledge Infrastructure databases. The case group consisted of patients with hypertension, and the control group consisted of subjects with normal blood pressure. Based on eleven published articles, involving 4837 cases and 5618 controls, the pooled results from rs2241766 polymorphism showed increased risk in the allelic model (G VS T: OR = 1.16, 95%CI = 1.06–1.27), recessive model (GG VS GT + TT: OR = 1.34, 95%CI = 1.10–1.63), dominant model (GG + GT VS TT: OR = 1.15, 95%CI = 1.02–1.30) and homozygote model (GG VS TT: OR = 1.38, 95%CI = 1.21–1.69). In addition, rs266729 polymorphism showed increased risk for hypertension in the recessive model (GG VS GC + CC: OR = 1.43, 95%CI = 1.02–2.01). In the Caucasian subgroup, rs1501299 polymorphism showed decreased risk of hypertension in the allelic model (T VS G: OR = 0.75, 95%CI = 0.58–0.97), dominant model (TT + TG VS GG: OR = 0.83, 95%CI = 0.71–0.98) and heterozygote model (TG VS GG: OR = 0.82, 95%CI = 0.68–0.99). The rs2241766 polymorphism was associated with a significant increase in hypertension risk based on our analysis. Moreover, an increased risk of rs266729 in hypertension patients was also detected. Our meta-analysis suggests that the rs1501299 polymorphism may play a protective role in hypertension in Caucasian subgroup; however, this finding requires further study.

Significant Association of Serum Adiponectin and Creatine Kinase-MB Levels in ST-Segment Elevation Myocardial Infarction

Aims: Adiponectin, an adipocyte-specific secretory protein, abundantly exists in the blood stream while its concentration paradoxically decreases in obesity. Hypoadiponectinemia is one of risks of cardiovascular diseases. However, impact of serum adiponectin concentration on acute ischemic myocardial damages has not been fully clarified. The present study investigated the association of serum adiponectin and creatine kinase (CK)-MB levels in subjects with ST-segment elevation myocardial infarction (STEMI).

Methods: This study is a physician-initiated observational study and is also registered with the University Hospital Medical Information Network (Number: UMIN 000014418). Patients were admitted to Senri Critical Care Medical Center, given a diagnosis of STEMI, and treated by primary percutaneous coronary intervention (PCI). Finally, 49 patients were enrolled and the association of serum adiponectin, CK-MB, and clinical features were mainly analyzed.

Results: Serum adiponectin levels decreased rapidly and reached the bottom at 24 hours after recanalization. Such reduction of serum adiponectin was inversely correlated with the area under the curve (AUC) of serum CK-MB (p = 0.013). Serum adiponectin concentrations were inversely correlated with AUC of serum CK-MB. In multivariate analysis, serum adiponectin concentration on admission (p = 0.002) and collateral (p = 0.037) were significantly and independently correlated with serum AUC of CK-MB.

Conclusion: Serum AUC of CK-MB in STEMI subjects was significantly associated with serum adiponectin concentration on admission and reduction of serum adiponectin levels from baseline to bottom. The present study may provide a possibility that serum adiponectin levels at acute phase are useful in the prediction for prognosis after PCI-treated STEMI subjects.

Adiponectin association with T-cadherin protects against neointima proliferation and atherosclerosis

Adiponectin, an adipocyte-derived protein abundant in the circulation, is thought to be protective against atherosclerosis. However, it is not fully understood how the association of adiponectin with vascular cells and its antiatherogenic effect are connected. In this study, T-cadherin was essential for accumulation of adiponectin in the neointima and atherosclerotic plaque lesions, and the adiponectin-T-cadherin association protected against vascular injury. In the apolipoprotein E-knockout (ApoE-KO) mice, adiponectin and T-cadherin colocalized on endothelial cells and synthetic smooth muscle cells in the aortic intima. Notably, aortic adiponectin protein disappeared in T-cadherin/ApoE double-knockout (Tcad/ApoE-DKO) mice with significant elevation of blood adiponectin concentration. Furthermore, in Tcad/ApoE-DKO mice, carotid artery ligation resulted in a significant increase of neointimal thickness compared with ApoE-KO mice. Finally, on a high-cholesterol diet, Tcad/ApoE-DKO mice increased atherosclerotic plaque formation, despite a 5-fold increase in plasma adiponectin level compared with that in ApoE-KO mice. In vitro, knockdown of T-cadherin from human aortic smooth muscle cells (HASMCs) with synthetic phenotype significantly reduced adiponectin accumulation on HASMCs and negated the inhibitory effect of adiponectin on proinflammatory change. Collective evidence showed that adiponectin accumulates in the vasculature via T-cadherin, and the adiponectin-T-cadherin association plays a protective role against neointimal and atherosclerotic plaque formations.-Fujishima, Y., Maeda, N., Matsuda, K., Masuda, S., Mori, T., Fukuda, S., Sekimoto, R., Yamaoka, M., Obata, Y., Kita, S., Nishizawa, H., Funahashi, T., Ranscht, B., Shimomura, I. Adiponectin association with T-cadherin protects against neointima proliferation and atherosclerosis.

Unravelling the adiponectin paradox: novel roles of adiponectin in the regulation of cardiovascular disease

Adipose tissue (AT) has recently been identified as a dynamic endocrine organ secreting a wide range of adipokines. Adiponectin is one such hormone, exerting endocrine and paracrine effects on the cardiovascular system. At a cellular and molecular level, adiponectin has anti-inflammatory, antioxidant and anti-apoptotic roles, thereby mitigating key mechanisms underlying cardiovascular disease (CVD) pathogenesis. However, adiponectin expression in human AT as well as its circulating levels are increased in advanced CVD states, and it is actually considered by many as a 'rescue hormone'. Due to the complex mechanisms regulating adiponectin's biosynthesis in the human AT, measurement of its levels as a biomarker in CVD is highly controversial, given that adiponectin exerts protective effects on the cardiovascular system but at the same time its increased levels flag advanced CVD. In this review article, we present the involvement of adiponectin in CVD pathogenesis and we discuss its role as a clinical biomarker.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

Genetic variants of CDH13 determine the susceptibility to chronic obstructive pulmonary disease in a Chinese population

AIM

Adiponectin has been implicated in the development of chronic obstructive pulmonary disease (COPD). The CDH13 gene encodes T-cadherin that is an adiponectin receptor, and genetic variants of CDH13 determine blood adiponectin levels. The aim of this study was to investigate the effects of CDH13 variants on COPD susceptibility in a Chinese population.

METHODS

Ten single-nucleotide polymorphisms (SNP) in CDH13 were screened using the SNaPshot method in 279 COPD patients and 367 control subjects. Association of genotypes or haplotypes constructed from these loci with COPD was analyzed in different genetic models.

RESULTS

Among the 10 SNPs tested, rs4783244 and rs12922394 exhibited significant differences in allele or genotype frequencies between COPD patients and control subjects, whereas 8 other SNPs did not. The minor allele T was associated with decreased risk of COPD in the recessive model at rs4783244 (OR=0.42, P=0.023) and in the dominant model at rs12922394 (OR=0.70, P=0.022). The genotype TT at either rs4783244 or rs12922394 was associated with a significantly low level of plasma adiponectin when compared to genotypes GG and CC (P<0.05). Haplotypes GC in block 1 (rs4783244-rs12922394) as well as GTAC and ATGT in block 3 (rs4783266-rs11640522-rs11646849-rs11860282) significantly increased the risk of COPD, whereas haplotypes TT in block 1, TG in block 2 (rs11646011- rs11640875) and ATGC in block 3 were protective against COPD.

CONCLUSION

CDH13 genetic variants determine Chinese individuals' susceptibility to COPD and thus are efficient genetic biomarkers for early detection of COPD.

Genetic Determination of Serum Levels of Diabetes-Associated Adipokines

Adipose tissue secretes an abundance of proteins. Some of these proteins are known as adipokines and adipose-derived hormones which have been linked with metabolic disorders, including type 2 diabetes, and even with cancer. Variance in serum adipokine concentration is often closely associated with an increase (obesity) or decrease (lipodystrophy) in fat tissue mass, and it is affected by age, gender, and localization of the adipose tissue. However, there may be genetic variants which, in consequence, influence the serum concentration of a certain adipokine, and thereby promote metabolic disturbances or, with regard to the "protective" allele, exert beneficial effects. This review focuses on the genetic determination of serum levels of the following adipokines: adiponectin, chemerin, leptin, progranulin, resistin, retinol binding protein 4, vaspin, adipsin, apelin, and omentin. The article reports on the latest findings from genome-wide association studies (GWAS) and candidate gene studies, showing variants located in/nearby the adipokine genes and other (non-receptor) genes. An extra chapter highlights adipokine-receptor variants. Epigenetic studies on adipokines are also addressed.