Deficiency of a new protein associated with cardiac syndrome X; called adropin

Adropin: A crucial regulator of cardiovascular health and metabolic balance

Adropin, a peptide discovered in 2008, has gained recognition as a key regulator of cardiovascular health and metabolic balance. Initially identified for its roles in energy balance, lipid metabolism, and glucose regulation, adropin has also been found to improve cardiovascular health by enhancing endothelial function, modulating lipid profiles, and reducing oxidative stress. These protective mechanisms suggest that adropin may be able to help prevent conditions such as atherosclerosis, hypertension, and other cardiovascular diseases. Research has established connections between adropin and cardiovascular risk factors, such as obesity, insulin resistance, and dyslipidemia, positioning it as a valuable biomarker for evaluating cardiovascular disease risk. New studies highlight adropin's diagnostic and prognostic significance, showing that higher levels are linked to better cardiovascular outcomes, while lower levels are associated with a higher risk of cardiovascular diseases. This review aims to summarize current knowledge on adropin, emphasizing its significance as a promising focus in the intersection of cardiovascular health and metabolic health. By summarizing the latest research findings, this review aims to offer insights into the potential applications of adropin in both clinical practice and research, leading to a deeper understanding of its role in maintaining cardiovascular and metabolic health.

Adropin may regulate corpus luteum formation and its function in adult mouse ovary

BACKGROUND

Adropin, a unique peptide hormone, has been associated with the regulation of several physiological processes, including glucose homeostasis, fatty acid metabolism, and neovascularization. However, its possible role in ovarian function is not understood. Our objective was to examine the expression of adropin and its putative receptor, GPR19, in the ovaries of mice at various phases of the estrous cycle.

METHODS

Immunohistochemistry and western blot analysis were performed to explore the localization and changes in expression of adropin and GPR19 in the ovaries during different phases of the estrous cycle in mice. Hormonal assays were performed with ELISA. An in vitro study was performed to examine the direct effect of adropin (10, 100 ng/ml) on ovarian function.

RESULTS

A western blot study showed that adropin and GPR19 proteins were maximum during the estrus phase of the estrous cycle. Interestingly, adropin and GPR19 displayed intense immunoreactivity in granulosa cells of large antral follicles and corpus luteum. This suggested the possible involvement of adropin in corpus luteum formation. Adropin treatment stimulated progesterone synthesis by increasing GPR19, StAR, CYP11A1, and 3β-HSD expressions, while it decreased estrogen synthesis by inhibiting 17β-HSD and aromatase protein expressions. Moreover, adropin treatment upregulated the cell cycle arrest-CDK inhibitor 1B (p27kip1), pERK1/2, and angiogenic protein (EG VEGF) that are involved in the process of luteinization.

CONCLUSIONS

Adropin GPR19 signaling promotes the synthesis of progesterone and upregulates the expression of p27kip1, EG VEGF, and erk1/2, resulting in cell cycle arrest and neovascularization, which ultimately leads to corpus luteum formation.

Feeding-induced hepatokines and crosstalk with multi-organ: A novel therapeutic target for Type 2 diabetes

Hyperglycemia, which can be caused by either an insulin deficit and/or insulin resistance, is the main symptom of Type 2 diabetes, a significant endocrine metabolic illness. Conventional medications, including insulin and oral antidiabetic medicines, can alleviate the signs of diabetes but cannot restore insulin release in a physiologically normal amount. The liver detects and reacts to shifts in the nutritional condition that occur under a wide variety of metabolic situations, making it an essential organ for maintaining energy homeostasis. It also performs a crucial function in glucolipid metabolism through the secretion of hepatokines. Emerging research shows that feeding induces hepatokines release, which regulates glucose and lipid metabolism. Notably, these feeding-induced hepatokines act on multiple organs to regulate glucolipotoxicity and thus influence the development of T2DM. In this review, we focus on describing how feeding-induced cross-talk between hepatokines, including Adropin, Manf, Leap2 and Pcsk9, and metabolic organs (e.g.brain, heart, pancreas, and adipose tissue) affects metabolic disorders, thus revealing a novel approach for both controlling and managing of Type 2 diabetes as a promising medication.

Serum Adropin Level in the Early Period of ST-Elevation Myocardial Infarction and Its Relationship With Cobalamin and Folic Acid

BACKGROUND

Studies on biomarkers in the diagnosis of myocardial infarction are ongoing. Adropin is a biomarker that has been studied and has been shown to have different effects. This study aimed to examine the adropin level of patients with myocardial infarction within the first 24 hours, as well as its relationship with cobalamin and folic acid.

MATERIAL AND METHODS

The control group included 70 patients whose troponin values did not increase and no coronary lesions were detected. In the ST-elevation myocardial infarction (STEMI) group, 70 patients with ST elevation on ECG and coronary total thrombosis on coronary angiography were evaluated. Coronary lesion severity was measured using the SYNergy between the percutaneous coronary intervention (PCI) with TAXUS and Cardiac Surgery (SYNTAX) score tool. Hemogram, troponin, adropin, C-reactive protein (CRP), cobalamin, folic acid, and other biochemical parameters were evaluated in all patients.

RESULTS

In the STEMI group, a significant increase was observed in the adropin level along with the troponin and CRP levels in the first 24 hours (p<0.001). Cobalamin and folic acid levels were low in the same group (p:0.016, p<0.001). While a strong negative correlation was observed between adropin and cobalamin, no correlation was found with other parameters.

CONCLUSION

The study supports that adropin could be used as a cardiac biomarker in the early stages of STEMI patients. Another result is with low cobalamin and folic acid levels in patients with myocardial infarction which needs to be further explained with the strong negative correlation between adropin and cobalamin.

Effect of Adropin on Pancreas Exocrine Function in a Rat Model: A Preliminary Study

The aim was to investigate the potential effect of adropin (ADR) on pancreatic−biliary juice (PBJ) secretion (volume, protein content, trypsin activity) in a rat model. The animals were divided into control and five experimental groups: adropin, CCK-8 (CCK-8 stimulation), capsaicin (capsaicin deactivation of afferents), vagotomy (vagotomy procedure), and vagal stimulation (vagal nerve stimulation). The experiment consisted of four phases, during which vehicle (0.9% NaCl) and three ADR boluses (5, 10, and 20 µg/kg BW) were administered i.v. every 30 min. PBJ samples were collected from each rat at 15 min intervals after boluses. Exogenous ADR failed to affect the pancreatic responses after vagotomy and the capsaicin pretreatment and reduced the PBJ volume, protein outputs, and trypsin activity in the adropin, CCK-8, and vagal stimulation groups in a dose-dependent manner. In all these groups, volume of PBJ was reduced only by the highest dose of ADR (p < 0.001 for adropin group and p < 0.01 for CCK-8 and vagal stimulation groups), and the protein outputs were reduced by the administration of ADR 10 µg/kg BW (adropin and CCK-8 groups, p < 0.01 in both cases) and 20 µg/kg BW (p < 0.001 for adropin and CCK-8 groups, p < 0.01 for vagal stimulation group). The 10 µg/kg BW dose of ADR reduced the trypsin output in the CCK-8 group (p < 0.01), and the highest ADR dose reduced the trypsin output in the CCK-8 (p < 0.001) and vagal stimulation (p < 0.01) groups. In conclusion, adropin in the analyzed doses exhibits the negative feedback pathway. This mechanism seems to participate in the regulation of pancreatic juice secretion via an indirect vagal mechanism.

The effectiveness of serum S100B, TRAIL, and adropin levels in predicting clinical outcome, final infarct core, and stroke subtypes of acute ischemic stroke patients

Introduction:

More than half of all worldwide deaths and disabilities were caused by stroke. Large artery atherosclerosis is identified as a high etiological risk factor because it accounts for 20% of ischemic stroke.

Objectives:

To identify the significance of TRAIL and adropin release and the relative changes related to S100B levels, as well as the relationship between these biomarkers and the final infarct core, the clinical outcome, and the presence of large artery atherosclerosis in acute stroke patients.

Materials and methods:

Over a one-year period, demographic, clinical, and neuroimaging findings of 90 consecutive patients with acute ischemic stroke were evaluated.

Results:

The mean age of participants was 69.28 ± 10 and 39 patients were female. The increased level of S100B and the decreased levels of sTRAIL with adropin were significantly associated with moderate to severe neurologic presentation (p=0.0001, p=0.002, p=0.002, respectively). On the control CT, a large infarct core was significantly associated with decreased serum levels of sTRAIL and adropin (p=0.001 and p=0.000, respectively); however, the levels of S100B were not significantly associated with good ASPECTS score (p=0.684). Disability and an unfavorable outcome were significantly related to the decreased level of sTRAIL and adropin (p=0.001 and p=0.000 for THRIVE score>5, respectively). Decreased sTRAIL and adropin levels and an increased S100B level were correlated with the presence of large artery atherosclerotic etiologic factors (p=0.000, p=0.000, p=0.036, respectively).

Conclusion:

TRAIL and adropin serum levels were associated with poor clinical outcomes and greater infarcted area in acute ischemic stroke patients.

Myricetin Increases Circulating Adropin Level after Activation of Glucagon-like Peptide 1 (GLP-1) Receptor in Type-1 Diabetic Rats

Myricetin is a common plant-derived flavonoid, considered an agonist of glucagon-like peptide 1 (GLP-1) receptor. It improves glycemic control and helps reduce body weight in diabetic subjects. The potential mechanisms of action of myricetin in this context might be enhancing the secretion of β-endorphin (BER) to activate peripheral μ-opioid receptors. Moreover, adropin is a nutritionally regulated peptide hormone, which regulates energy metabolism, and plays a role in ameliorating diabetes. Because their mechanisms of insulin sensitivity are closely related, we hypothesized that myricetin may interact with adropin and plasma BER. The present study investigated the glucose-lowering effect of acute and chronic treatments of myricetin in type-1 diabetic rats. Plasma BER and adropin levels were determined by enzyme-linked immunosorbent assay (ELISA). The secretion of BER was measured in rats who received adrenalectomy. The changes in adropin gene (Enho) or mRNA level of GLP-1 receptor were measured using qPCR analysis. The results showed that myricetin dose-dependently increased plasma BER and adropin levels like the reduction of hyperglycemia after bolus injection as acute treatment. In addition, these effects of myricetin were inhibited by the antagonist of GLP-1 receptor. Moreover, in HepG2 cell line, myricetin induced GLP-1 receptor activation, which modulated the expression of adropin. In diabetic rats, the plasma adropin increased by myricetin is mainly through endogenous β-endorphin after activation of GLP-1 receptor via bolus injection as acute treatment. Additionally, chronic treatment with myricetin increased adropin secretion in diabetic rats. In conclusion, our results provide a new finding that activation of opioid μ-receptor in the liver may enhance circulating adropin in animals.

Expression of Circulating MicroRNAs and Myokines and Interactions with Serum Osteopontin in Type 2 Diabetic Patients with Moderate and Poor Glycemic Control: A Biochemical and Molecular Study

BACKGROUND

Cellular miRNAs are expressed in tissue fluids with sufficient amounts and were identified as potential molecular targets for studying the physiological mechanisms and correlations with many human diseases particularly diabetes. However, molecular-based changes among older adults with diabetes mellitus (DM) are rarely fully elucidated.

AIM

This study is aimed at identifying circulating miRNAs, which hold the potential to serve as biomarkers for the immune-inflammatory changes in older T2D patients with moderate and poor glycemic control status. In addition, the association of both myokines and osteopontin (OPN) levels with circulating miRNAs was identified.

METHODS

A total of 80 subjects aged 20-80 years were invited during the period of October 2017-May 2018 to participate in this descriptive cross-sectional study. All subjects were diagnosed with T2D for more than 5 years. Subjects were grouped based on glycemic control (HbA1c values) into two groups: moderate glycemic control (>7-8% HbA1c, no = 30) and poor glycemic control (>8% HbA1c, no = 50), respectively. Diabetic control parameters, fasting blood sugar (FS), HbA1c, fasting insulin (IF), insulin resistance (IR), HOMA-IR, inflammatory cytokines (IL-6, IL-8, IL-18, IL-23, TNF-α, and CRP), osteopontin, and myokines (adropin and irisin) were estimated by colorimetric and immune ELISA assays, respectively. In addition, real-time RT-PCR analysis was performed to evaluate the expression of circulating miRNAs, miR-146a and miR-144, in the serum of all diabetic subjects.

RESULTS

In this study, T2D patients with poor glycemic control showed a significant increase in the serum levels of IL-6, IL-8, IL-18, IL-23, TNF-α, CRP, and OPN and a reduction in the levels of myokines, adropin and irisin, compared to patients with moderate glycemic control. The results obtained are significantly correlated with the severity of diabetes measured by HbA1c, FS, IF, and HOMA-IR. In addition, baseline expression of miR-146a is significantly reduced and miR-144 is significantly increased in T2D patients with poor glycemic control compared to those with moderate glycemic control. In all diabetic groups, the expression of miR-146a and miR-144 is significantly correlated with diabetic controls, inflammatory cytokines, myokines, and serum levels of OPN. Respective of gender, women with T2D showed more significant change in the expressed miRNAs, inflammatory cytokines, OPN, and serum myokine markers compared to men. ROC analysis identified AUC cutoff values of miR-146a, miR-144, adropin, irisin, and OPN expression levels with considerable specificity and sensitivity which recommends the potential use of adropin, irisin, and OPN as diagnostic biomarkers for diabetes with varying glycemic control status.

CONCLUSION

In this study, molecular expression of certain microRNA species, such as miR-146a and miR-144, was identified and significantly associated with parameters of disease severity, HbA1c, inflammatory cytokines, myokines, and serum osteopontin in T2D patients with moderate and poor glycemic control. The AUC cutoff values of circulating miRNAs, miR-146a and miR-144; myokines, adropin and irisin; and serum OPN were significantly identified by ROC analysis which additionally recommends the potential use of these biomarkers, miR-146a, miR-144, adropin, irisin, and OPN, as diagnostic biomarkers with considerable specificity and sensitivity for diabetes in patients with varying glycemic control status.

Role of Adropin in Cardiometabolic Disorders: From Pathophysiological Mechanisms to Therapeutic Target

Although a large amount of data supports the crucial role of endothelial dysfunction (ED) in cardiovascular diseases (CVDs), there is a large bench-to-bedside chasm between basic and clinical research of ED, limiting the implementation of these findings in everyday clinical settings. Hence, it is important to further investigate the pathophysiological mechanisms underlying ED and find modalities that will alleviate its clinical implementation. Adropin, a highly conserved peptide hormone secreted primarily by the liver, recently emerged as an important regulatory component of the vascular endothelium. Specifically, the vasoprotective role of adropin is achieved mainly by affecting endothelial NO synthesis. Thus, in this review, we aimed to summarize the current knowledge regarding the role of adropin in physiological processes and address the protective role of adropin in endothelium with consequent implications to CV pathologies. We focused on data regarding the role of adropin in the clinical setting, with concurrent implications to future clinical use of adropin. Studies suggest that plasma levels of adropin correlate with indices of ED in various pathologies and enhanced disease progression, implying that adropin may serve as a useful biomarker of ED in the upcoming future. On the other hand, despite notable results with respect to therapeutic potential of adropin in preliminary experiments, further well-designed studies are warranted in order to establish if adropin might be beneficial in this setting.

Adropin Serum Levels in Patients with Primary Sjögren's Syndrome

Primary Sjögren’s syndrome (pSS) patients have higher prevalence of endothelial dysfunction and premature atherosclerosis. Recent studies investigated adropin, a secretory protein that can regulate lipid metabolism and insulin resistance and protect endothelial cells’ function and that has an anti-inflammatory effect. The aim of this study was to determine adropin levels in pSS patients compared to healthy controls. Additional goals were exploring the correlation between adropin and several metabolic and immunological parameters in pSS, including disease specific antibodies, EULAR Sjögren’s Syndrome Disease Activity Index (ESSDAI), and Sjögren’s Syndrome Disease Damage Index (SSDDI). This research included 52 pSS patients and 52 healthy controls. pSS patients have significantly higher adropin levels compared to the control group (3.76 ± 0.68 vs. 3.14 ± 0.69 ng/mL, p < 0.001). Correlation analysis showed that adropin levels in pSS patients have positive correlation with high-density lipoprotein (HDL) (r = 0.290, p = 0.036) and anti SSA/Ro52 antibodies (r = 0.307, p = 0.026) and negative correlation with SSDDI (r = −0.401, p = 0.003). Multivariant linear regression showed that adropin levels are independently associated with HDL (β ± SE, 0.903 ± 0.283, p = 0.002) and SSDDI (β ± SE, −0.202 ± 0.073, p = 0.008). Our findings imply that adropin could be involved in the pathophysiology of pSS, yet it remains to be elucidated in future studies whether adropin has a protective or detrimental role in this setting.

New Peptides as Potential Players in the Crosstalk Between the Brain and Obesity, Metabolic and Cardiovascular Diseases

According to the World Health Organization report published in 2016, 650 million people worldwide suffer from obesity, almost three times more than in 1975. Obesity is defined as excessive fat accumulation which may impair health with non-communicable diseases such as diabetes, cardiovascular diseases (hypertension, coronary artery disease, stroke), and some cancers. Despite medical advances, cardiovascular complications are still the leading causes of death arising from obesity. Excessive fat accumulation is caused by the imbalance between energy intake and expenditure. The pathogenesis of this process is complex and not fully understood, but current research is focused on the role of the complex crosstalk between the central nervous system (CNS), neuroendocrine and immune system including the autonomic nervous system, adipose tissue, digestive and cardiovascular systems. Additionally, special attention has been paid to newly discovered substances: neuropeptide 26RFa, preptin, and adropin. It was shown that the above peptides are synthesized both in numerous structures of the CNS and in many peripheral organs and tissues, such as the heart, adipose tissue, and the gastrointestinal tract. Recently, particular attention has been paid to the role of the presented peptides in the pathogenesis of obesity, metabolic and cardiovascular system diseases. This review summarizes the role of newly investigated peptides in the crosstalk between brain and peripheral organs in the pathogenesis of obesity, metabolic, and cardiovascular diseases.

Exercise in the cold causes greater irisin release but may not be enough for adropin

When irisin and adropin were discovered, it was popularly hoped that they would become therapies for metabolic disorders that threaten global health. However, contradictory results have been reported in the subsequent period. Irisin, induced by exercise or cold exposure, is believed to be a myokine that causes the browning of adipose tissue thus increasing energy expenditure. Adropin is thought to be beneficial for health by regulating blood flow, capillary density, and playing an active role in glucose and insulin homeostasis. However, there were no experimental studies investigating the simultaneous effect of exercise and cold exposure in humans. The purpose of this study was to investigate irisin and adropin responses in young healthy individuals performing aerobic exercise in different environmental temperatures. Twenty-seven young, healthy individuals participated in this study. Participants performed 40 min of aerobic running exercise in environmental temperatures of 0°C, 12°C, and 24°C. Venous blood samples were taken pre- and post-exercise. Irisin and adropin levels were analyzed using an enzyme-linked immunosorbent assay. The principal findings showed that while serum irisin concentrations significantly increased after aerobic exercise was performed at an environmental temperature of 0°C, there was no significant difference between pre- and post-exercise recordings for physical activity performed at 12°C and 24°C. Adropin concentrations, however, remained unchanged between pre- and post-exercise at 0°C, 12°C, and 24°C. Interestingly, the exercise at 0°C caused an increase in adropin (12.5%), but this amount was not enough to be a statistically significant result. The findings of this study suggest that aerobic exercise in a cold environment causes greater irisin release. However, the combined effect of exercise and cold exposure may not be enough to statistically increase adropin level.

Helicobacter pylori infection and susceptibility to cardiac syndrome X: A systematic review and meta-analysis

BACKGROUND

Cardiac syndrome X (CSX) is characterized by persistent angina with normal coronary arteries. Several pathophysiologic mechanisms have been introduced, particularly Helicobacter pylori (H. pylori) infection.

AIM

To investigate the association between H. pylori infection and CSX.

METHODS

All studies related to H. pylori infection and CSX were evaluated by comprehensive searches of global databases such as ISI Web of Knowledge, PubMed, Scopus, EMBASE, and Google scholar. Statistical analyses of selected articles were evaluated based on the summary odds ratio (OR). Finally, heterogeneity and publication bias were estimated using the I² statistic and Cochrane Q-test as well as Begg’s and Egger’s tests.

RESULTS

A total of 11 studies met our inclusion criteria and 1435 patients (63% female, and 37% male) were reviewed. A significant association was observed between female patients and this syndrome (P = 0.02). Our results showed a positive association between infection with this pathogen and presence of CSX (OR: 5.65; 95% confidence interval [CI]: 4.17-7.64; I²: 82.20). However, no significant association was observed with cagA-positive H. pylori strains and this syndrome (OR: 0.97; 0.56-1.70 with 95%CI). Given the heterogeneity and publication bias, the results need to confirmed by further prospective investigation.

CONCLUSION

Based on our results, H. pylori infection is associated with an increased risk of CSX. This bacterium appears to play a major role in the pathogenesis of CXS by inducing persistent inflammation.

Effects of eight weeks exercise training on serum levels of adropin in male volleyball players

OBJECTIVES

To evaluate the effects of an eight week exercise program on the lipid profile in serum, serum levels of adropin, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in male volleyball players.

METHODS

Sixteen healthy male volleyball players participated in this study. Subjects performed eight weeks of aerobic and resistance training, and body mass index (BMI), body fat ratio, total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), adropin, SBP, and DBP values were measured at the start (untrained) and end (trained) of training. Non-HDL-C was calculated by subtracting HDL-C from TC.

RESULTS

Body fat percentage and BMI values decreased significantly after eight weeks of exercise training. There was a statistically significant decrease in the post-test values of LDL-C, TG, non-HDL-C, and DBP compared to pre-test measurements. There was a significant increase in the trained levels of adropin and HDL-C compared to untrained levels. Pearson's correlation analyses revealed a negative and significant relationship between changes in DBP and adropin levels before and after exercise.

CONCLUSIONS

Eight weeks of exercise training decreased LDL-C, TG, non-HDL-C, and DBP and an increased serum levels of adropin in male volleyball players.

Adropin and apelin-12 efficiently predict metabolic syndrome in obese children

OBJECTIVE

Metabolic syndrome (MetS) is the most common condition associated with childhood and adolescent obesity and is a challenging public health issue. Very few studies have described the specificity and sensitivity of serum levels of adropin and apelin-12 as predictors of MetS. The aim of this study was to evaluate the association between serum levels of adropin and apelin-12 and MetS, and their sensitivity as predictors of MetS in obese children.

METHODS

This study involved 138 children. The study group included obese subjects with MetS, and the two control groups included obese subjects without MetS and normal weight subjects. Anthropometric parameters and clinical data were collected. Plasma levels of apelin-12, adropin, leptin, adiponectin, and TNF-α were also measured.

RESULTS

Obese children with MetS had significantly higher levels of apelin-12 and significantly lower levels of adropin when compared with those in children without MetS. In logistic regressions, we identified that apelin-12 was a risk factor for metabolic syndrome, and adropin was a protecting factor of having MetS after adjusting for age, sex, and puberty. Furthermore, ROC analysis revealed that adropin and apelin-12 are more sensitive predictors of metabolic syndrome than leptin and adiponectin.

CONCLUSION

Serum adropin and apelin-12 levels can be useful biomarkers for predicting MetS in obese children. Our findings could provide a novel approach for the treatment and prevention of MetS.

ADROPIN - POTENTIAL LINK IN CARDIOVASCULAR PROTECTION FOR OBESE MALE TYPE 2 DIABETES MELLITUS PATIENTS TREATED WITH LIRAGLUTIDE

The aim of this study was to determine plasma adropin concentration and parameters of insulin resistance in obese male type 2 diabetes mellitus (T2DM) patients before and after 3-month liraglutide treatment. In this interventional study, we enrolled 15 obese male T2DM patients with body mass index (BMI) >35 kg/m2, uncontrolled disease and HbA1c >7.5%, having previously taken taking two oral antidiabetic drugs. We modified their therapy to metformin and liraglutide for the next three months. After three months of liraglutide treatment, we observed significant decrease in body weight (from 111.5±18.7 kg to 109.2±17.5 kg, p=0.016) and BMI (from 40.9±7.3 to 40.1±7.0 kg/m2, p=0.021). Plasma adropin concentration increased significantly (p=0.003) compared with baseline. Fasting plasma insulin level decreased from 17.79±6.53 to 13.38±3.51 mU/L (p=0.002), fasting plasma glucose level decreased from 8.66±3.07 to 7.41±2.21 mmol/L (p=0.004) and HbA1c decreased from 7.98±0.70% to 7.26±0.36% (p=0.003). Insulin resistance presented as HOMA-IR decreased significantly from 7.30±5.19 to 4.52±2.61 (p=0.002). Systolic blood pressure, lipid status, liver and kidney function improved, but not reaching statistical significance. Treating obese male T2DM patients with liraglutide resulted in a significantly higher plasma adropin concentration, significant weight loss and improved parameters of insulin resistance, i.e. decreased fasting plasma insulin, plasma glucose levels and HOMA-IR.

A Review of Adropin as the Medium of Dialogue between Energy Regulation and Immune Regulation

Adropin is a secretory protein encoded by the energy balance gene and is closely associated with regulation of energy metabolism and insulin resistance. The clinical findings demonstrated its decreased expression in various inflammatory diseases, its negative correlation with the expression levels of inflammatory cytokines, and its potential anti-inflammatory effects. We speculate that adropin plays a pivotal regulatory role in immune cells and inflammatory factors. In this study, we reviewed the advances in researches concentrated on immunological effects of adropin.

Association of polymorphisms of preptin, irisin and adropin genes with susceptibility to coronary artery disease and hypertension

OBJECTIVES

Preptin, irisin and adropin are 3 new players in energy regulation that are related body mass index, lipids, glucose and insulin levels which may affect incidence of cardiovascular diseases. The aim of the present study was to evaluate eight single nucleotide polymorphisms (SNPs) of preptin genes (rs1003483, rs1004446, rs2239681, rs680, and rs3741204), irisin (rs16835198 and rs3480) and adropin (rs2281997) gene in patients with coronary artery disease (CAD) and hypertension.

METHODS

This case-control study was carried out on 372 volunteers, which were divided into 3 subgroups including: CAD patients with hypertension (CAD+H+), CAD patients with no hypertension (CAD+H-), and non-hypertensive non-CAD subjects as control group (CAD-H-) as health control. Genomic DNA from whole blood was extracted and eight SNPs were assessed using polymerase chain reaction- ligase detection reaction method.

RESULTS

A significant difference was found in the genotype and allele frequency of preptin rs1003483 gene in CAD+H+ compared to CAD+H- groups (P = .019 and P = .018, respectively). Allele frequency of rs1003483 was significantly different between CAD+H- groups and healthy control groups (P = .043). There also existed a significant difference the genotype frequency of rs1004446 gene in CAD+H+ compared to CAD+H- groups (P = .027).

CONCLUSIONS

The findings of present study revealed that the preptin rs1003483 and rs1004446 gene polymorphism might serve as predisposing factor in CAD and hypertension.

Adropin as A Fat-Burning Hormone with Multiple Functions-Review of a Decade of Research

Adropin is a unique hormone encoded by the energy homeostasis-associated (Enho) gene. Adropin is produced in the liver and brain, and also in peripheral tissues such as in the heart and gastrointestinal tract. Furthermore, adropin is present in the circulatory system. A decade after its discovery, there is evidence that adropin may contribute to body weight regulation, glucose and lipid homeostasis, and cardiovascular system functions. In this review, we summarize and discuss the physiological, metabolic, and pathophysiological factors regulating Enho as well as adropin. Furthermore, we review the literature addressing the role of adropin in adiposity and type 2 diabetes. Finally, we elaborate on the role of adropin in the context of the cardiovascular system, liver diseases, and cancer.

Serum adropin as a predictive biomarker of erectile dysfunction in coronary artery disease patients

Introduction

Erectile dysfunction (ED) is associated with various comorbidities and an early diagnosis and treatment is necessary to avoid the development of these comorbidities. Unfortunately, there is no biochemical marker that can be used for early diagnosis of ED. Nitric oxide (NO) is released by nerve and endothelial cells in the corpora cavernosa of the penis and is believed to be the main vasoactive chemical mediator of penile erection. Adropin is a regulatory peptide which has effects on NO bioavailability and energy homeostasis. We hypothesized that adropin may contribute to the pathogenesis of ED because of the presence of both metabolic effects and the influence on NO bioavailability. To confirm this hypothesis, we investigated the relationship between ED and serum adropin and NO levels.

Material and methods

Seventy-five ED patients were enrolled for this study and the patients were divided into two groups according to angiographic scoring. Serum NO and adropin levels were measured by the Griess reaction and ELISA method, respectively.

Results

Serum adropin and NO levels were found to be lower in the group which has higher angiographic score and the difference in NO was statistically significant. Also, adropin has a significant correlation between IIEF scores in ED patients.

Conclusions

This is the first study in the literature investigating the levels of adropin in ED patients having coronary artery disease. The adropin molecule shows a promising future in clarifying the etiopathogenesis of ED. More comprehensive and multicenter studies are needed to reveal the role of adropin in ED and the effects of treatment on this molecule.

Negative association between serum adropin and hypertensive disorders complicating pregnancy

Objective: Study the association of adropin and hypertensive disorders complicating pregnancy (HDCP). Methods: Patients with HDCP were matched with normotensive women (47 pairs). Adropin concentrations were detected by enzyme-linked immunosorbent assay. Results: Compared with the controls, the serum adropin levels were lower in the HDCP group (P < 0.001) and in HDCP subgroups (gestational hypertension, mild preeclampisa, and severe preeclampsia, term, preterm, early onset, and late onset) (all P < 0.05). After adjustment for confounders, adropin remained negatively associated with HDCP (P = 0.027). Conclusion: Lower adropin concentration is significantly associated with HDCP, suggesting that higher or normal adropin levels may be protective against HDCP.

Adropin reduces hypoxia/reoxygenation-induced myocardial injury via the reperfusion injury salvage kinase pathway

Adropin is a secreted polypeptide that has been demonstrated to serve an important role in protecting the vascular endothelium. Pharmacological activation of pro-survival kinases, such as PI3K-Akt and ERK1/2, are involved in the reperfusion injury salvage kinase (RISK) pathway. In the present study, the effects of adropin in cardiomyocyte injury induced by simulated ischemia/reperfusion (SI/R) were assessed. Additionally, the current study also assessed the mechanisms that govern SI/R in a H9c2 cardiomyoblast cell model. Cell viability was measured using an MTT assay. Cell injury was assessed using creatine kinase MB measurements. Apoptosis was assessed using flow cytometry and caspase-3 activity. The inflammatory response was measured using tumor necrosis factor α and interleukin-10 expression. Oxidative stress was assessed using malondialdehyde and superoxide dismutase. The expression levels of Akt, ERK1/2, glycogen synthase kinase 3β (GSK3β), Bcl-2 and Bax were determined using western blot analysis. The results of the current study revealed that moderate-dose adropin increased cell viability, reduced early apoptosis and caspase-3 activity, promoted Bcl-2 expression, inhibited Bax and increased the Bcl-2/Bax ratio. Adropin significantly increased the phosphorylation of Akt, ERK1/2 and GSK3β, whereas inhibitors of PI3K and ERK1/2, respectively, LY294002 and PD98059, abolished the cardioprotective role of adropin. Furthermore, no significant difference was observed in phosphorylated-STAT3/total-STAT3 expression between the adropin and SI/R groups and Janus kinase 2 inhibitor AG490 did not significantly inhibit the protective role of adropin. These results indicate that adropin exerts a protective effect against SI/R injury through the RISK pathway instead of the survivor activating factor enhancement pathway.

Alterations of irisin, adropin, preptin and BDNF concentrations in coronary heart disease patients comorbid with depression

Background

Depression is a well-known co-morbidity of coronary heart disease (CHD) and these two diseases share common risk mechanisms. Here, the aim of this study was to investigate the possible link between energy homeostasis regulation and CHD patients comorbid with depression.

Methods

Two hundred and nine CHD patients and 101 matched healthy individuals were included. Demographic, clinical data were collected, serum irisin, adropin, preptin and brain-derived neurotrophic factor (BDNF) levels were determined by a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), and the depression was scored by Patient Health Questionnaire-9 (PHQ-9). Correlation analysis as well as multiple linear regression was used to assess the relationship between the three peptides, BDNF serum levels and PHQ-9 scores.

Results

Irisin serum level was significantly lower in CHD patients without depression as compared with healthy controls (P=0.002), as well as adropin (P=0.000), preptin (P=0.000) and BDNF (P=0.000). Furthermore, similar trends were observed in CHD patients with depression in terms of irisin, adropin and BDNF as compared with CHD patients without depression (P=0.006; P=0.003; P=0.002; respectively). Multiple logistic regression results confirmed the contribution of irisin and BDNF to the occurrence of depression in CHD. Interestingly, correlations analysis revealed significant negative correlations between PHQ-9 scores and irisin, adropin, BDNF level (r=-0.43, P<0.01; r=-0.29, P<0.05; r=-0.45, P<0.001 respectively), and irisin serum level was positively correlated with BDNF (r=0.38, P<0.01).

Conclusions

Our study firstly identified the role of energy homeostasis in the susceptibility to depression in CHD patients, and the interaction between irisin and BDNF could trigger the imbalance of energy homeostasis that occurs in depression of CHD patients.

Vasodilatory function in human skeletal muscle feed arteries with advancing age: the role of adropin

KEY POINTS

The present study aimed to determine the impact of ageing on endogenous adropin levels in human skeletal muscle feed arteries (SMFAs) and the role of adropin in age-related vascular dysfunction. Adropin protein expression falls progressively with advancing age in the human peripheral vasculature. Endothelial-dependent vasodilatation, typically attenuated with age, was strongly correlated with SMFA adropin protein levels. Adropin incubation restored age-related endothelial-dependent vasodilatory dysfunction and increased the phosphorylated endothelial nitric oxide synthase (eNOS)/eNOS ratio in an age-dependent manner in the SMFAs. The role of nitric oxide bioavailability was additionally indicated by NOS blockade ablating both the positive vascular effects of adropin incubation and the relationship between endothelial function and adropin protein expression. Additional evidence of a mechanistic link between declining adropin and age-related endothelial dysfunction was documented by a progressively increasing magnitude of effect of adropin-induced eNOS-mediated vasodilatation with ageing. Adropin appears to be a novel therapeutic target for facilitating the restoration of endothelial function with ageing.

ABSTRACT

The present study aimed to determine the impact of advancing age on endogenous adropin levels in human skeletal muscle feed arteries (SMFAs) and the role of adropin in age-related vascular dysfunction. Adropin protein expression and vasodilatory capacity was assesed in SMFAs from Young (27 ± 2 years, n = 10), Middle Aged (54 ± 2 years, n = 10) and Old (75 ± 2 years, n = 16) subjects. Endothelial-dependent vasodilatation, with and without adropin incubation, was assessed in response to flow-induced shear stress and ACh. Both SMFA adropin protein expression and endothelial-dependent vasodilatory function exhibited a progressive, age-related, reduction (Flow: Y: 65 ± 3%; Middle Aged: 36 ± 3%; Old: 15 ± 2%; ACh: Young: 63 ± 2%, Middle Aged: 34 ± 3%; Old: 23 ± 3%, P < 0.05). There was a strong positive correlation between SMFA adropin protein expression and both flow (r = 0.81, P < 0.05) and ACh (r = 0.78, P < 0.05). Adropin incubation in the Middle Aged and Old SMFAs restored the vasodilatory response to flow (Middle Aged + Adropin: 59 ± 3%; Old + Adropin: 47 ± 3%, P < 0.05) and ACh (Middle Aged + Adropin: 59 ± 3%; Old + Adropin: 49 ± 2%, P < 0.05). A mechanistic link between adropin and nitric oxide (NO) biovavailabilty was supported by (i) increased phosphorylated endothelial NO synthase (eNOS)/eNOS protein expression with adropin incubation only in the Middle Aged and Old SMFAs; (ii) eNOS blockade ablating both the positive vascular effects of adropin incubation and the relationship between endothelial function and adropin protein expression and (iii) a progressive increase in the magnitude of effect of adropin-induced eNOS-mediated vasodilatation with advancing age. Adropin could be a novel therapeutic target for facilitating the restoration of endothelial function via increased NO bioavailability, with advancing age.

Age-Dependent Decrease in Adropin is Associated with Reduced Levels of Endothelial Nitric Oxide Synthase and Increased Oxidative Stress in the Rat Brain

Adropin is a peptide highly expressed in the brain. Emerging evidence indicates that low plasma levels of adropin are closely associated with aging and endothelial dysfunction. We hypothesized that aging reduces adropin levels in the brain, which correlates with reduced endothelial nitric oxide synthase (eNOS) and increased oxidative stress associated with age-related endothelial dysfunction. Cortical brain tissue and plasma were collected from young (10-12 weeks old) and aged (18-20 months old) male Sprague-Dawley naïve rats. Using RT-qPCR, we quantified the mRNA levels of the energy homeostasis associated (Enho) gene encoding for adropin. Western blotting was utilized to measure adropin and markers of endothelial dysfunction and oxidative stress in the brain tissue. Levels of adropin in plasma were measured using an ELISA kit. Compared to young rats, both Enho mRNA and protein levels were dramatically reduced in the aged rat brain, which was accompanied by a significant reduction in plasma adropin levels in aged compared to young rats. Additionally, total and phosphorylated levels of endothelial nitric oxide synthase (eNOS) were significantly decreased in aged rat brains and were associated with dramatically increased gp91^phox-containing NADPH oxidase (a major source of free radicals) and 4-hydroxynonenal (4-HNE), a lipid peroxidation marker. Brain levels of Akt and caveolin-1 were significantly reduced in aged rats compared with young animals. Collectively, these findings indicate that adropin levels negatively correlate with markers of endothelial dysfunction and oxidative injury, which raises the possibility that loss of brain adropin might play a role in the pathogenesis and development of aging-associated cerebrovascular dysfunction.

Tilapia adropin: the localization and regulation of growth hormone gene expression in pituitary cells

The peptide hormone adropin, encoded by the energy homeostasis-associated (Enho) gene, plays a role in energy homeostasis and the control of vascular function. The aim of this study was to examine the role of adropin in growth hormone (GH) gene expression at the pituitary level in tilapia. As a first step, the antiserum for the tilapia adropin was produced, and its specificity was confirmed by antiserum preabsorption and immunohistochemical staining in the tilapia pituitary. Adropin could be detected immunocytochemically in the proximal pars distalis (PPD) of the tilapia pituitary. In primary cultures of tilapia pituitary cells, tilapia adropin was effective in increasing GH mRNA levels. However, removal of endogenous adropin by immunoneutralization using adropin antiserum inhibited GH gene expression. In parallel experiments, pituitary cells co-treated with ovine pituitary adenylate cyclase activating polypeptide 38 (oPACAP38) and adropin showed a similar increase level compared to those treated with oPACAP38 alone, whereas insulin-like growth factor 1 (IGF1) not only had an inhibitory effect on basal GH mRNA levels, but also could abolish adropin stimulation of GH gene expression. In pituitary cells pretreated with actinomycin D, the half-life of GH mRNA was enhanced by adropin. Taken together, these findings suggest that adropin may serve as a novel local stimulator for GH gene expression in tilapia pituitary.

Association between serum adropin level and burden of coronary artery disease in patients with non-ST elevation myocardial infarction

Objective:

Previous studies revealed the relationship between stable coronary artery disease (CAD) and serum adropin level, but this relationship has not been investigated in patients with non-ST segment elevation myocardial infarction (NSTEMI). The present study is an analysis of the relationship between adropin and severity of CAD assessed based on SYNTAX score in patients with NSTEMI.

Methods:

A total of 109 participants, 80 patients with NSTEMI and 29 healthy individuals, were prospectively enrolled in the study. Patients with NSTEMI were divided to 2 groups: high SYNTAX score (≥32) (35 patients) and low SYNTAX score (<32) (45 patients). Adropin level was measured from blood serum samples using enzyme-linked immunosorbent assay test.

Results:

Patients with NSTEMI and high SYNTAX score had significantly lower serum adropin level (2357.30 pg/mL±821.58) compared to NSTEMI patients with low SYNTAX score (3077.00 pg/mL±912.86) and control group (3688.00±956.65). Adropin cut-off value for predicting high SYNTAX score on receiver-operating characteristic curve analysis was determined to be 2759 pg/mL, with a sensitivity of 63% and a specificity of 57%. Adropin was an independent predictor for high SYNTAX score (odds ratio=0.999; 95% confidence interval: 0.998–1.000; p=0.007).

Conclusion:

Adropin could be an alternative blood sample value for predicting severity of CAD.

Association between aerobic exercise training effects of serum adropin level, arterial stiffness, and adiposity in obese elderly adults

Serum levels of adropin, which enhances endothelial cell release of nitric oxide (NO), are lower in obese patients. Although habitual aerobic exercise reduces arterial stiffness and adiposity, the relationship between these effects and circulating levels of adropin remains unclear. The purpose of this study was to determine if serum adropin level is associated with the effects of aerobic exercise training on arterial stiffness and adiposity in obese adults. In Experiment 1, we examined whether serum adropin levels are associated with cardiorespiratory fitness, carotid β-stiffness, plasma nitrite/nitrate (NOx) level, and abdominal visceral fat in 27 normal, 20 overweight, and 25 obese adults (age, 41-79 years). In Experiment 2, we examined the effects of an 8-week aerobic exercise training program on the relationship between serum adropin level and arterial stiffness or adiposity in 13 obese adults (age, 54-76 years). Serum adropin levels in normal, overweight, and obese adults negatively correlated with carotid β-stiffness and abdominal visceral fat, and positively correlated with plasma NOx level and cardiorespiratory fitness. After the 8-week exercise program, serum adropin levels in obese adults were elevated, and correlated with training-induced changes in carotid β-stiffness (r = -0.573, P < 0.05), plasma NOx level (r = 0.671, P < 0.05), and abdominal visceral fat (r = -0.585, P < 0.05). These findings suggest that the exercise training-induced increase in serum adropin may be related to the training effects of arterial stiffness and adiposity in obese adults.

Salusins and adropin: New peptides potentially involved in lipid metabolism and atherosclerosis

Dyslipidemia is one of the most potent risk factors for the development of atherosclerosis. The high atherosclerotic risk in dyslipidemic patients is associated with endothelial dysfunction. During the last two decades, novel bioactive peptides have emerged as potential biomarkers of endothelial dysfunction and dyslipidemia-salusins and adropin. Salusin-alpha is likely to prevent atherosclerosis, while salusin-beta may act as a potential proatherogenic factor. Adropin was recently identified as important for energy homeostasis and lipid metabolism. Adropin is closely related to the inhibition of atherosclerosis by up-regulation of the endothelial nitric oxide synthase expression through the vascular endothelial growth factor receptor-2. These peptides represent a novel target to limit diseases characterized by endothelial dysfunction and may form the basis for the development of new therapeutic agents for treating metabolic disorders associated with atherosclerosis.

Inverse association between carbohydrate consumption and plasma adropin concentrations in humans

OBJECTIVE

The role of metabolic condition and diet in regulating circulating levels of adropin, a peptide hormone linked to cardiometabolic control, is not well understood. In this study, weight loss and diet effects on plasma adropin concentrations were examined.

METHODS

This report includes data from (1) a weight loss trial, (2) an evaluation of acute exercise effects on mixed-meal (60% kcal from carbohydrates) tolerance test responses, and (3) a meta-analysis to determine normal fasting adropin concentrations.

RESULTS

Distribution of plasma adropin concentrations exhibited positive skew and kurtosis. The effect of weight loss on plasma adropin concentrations was dependent on baseline plasma adropin concentrations, with an inverse association between baseline and a decline in concentrations after weight loss (Spearman's ρ = -0.575; P < 0.001). When ranked by baseline plasma adropin concentrations, only values in the upper quartile declined with weight loss. Plasma adropin concentrations under the main area of the bell curve correlated negatively with habitual carbohydrate intake and plasma lipids. There was a negative correlation between baseline values and a transient decline in plasma adropin during the mixed-meal tolerance test.

CONCLUSIONS

Plasma adropin concentrations in humans are sensitive to dietary macronutrients, perhaps due to habitual consumption of carbohydrate-rich diets suppressing circulating levels. Very high adropin levels may indicate cardiometabolic conditions sensitive to weight loss.

Adropin reduces paracellular permeability of rat brain endothelial cells exposed to ischemia-like conditions

Adropin is a peptide encoded by the energy homeostasis associated gene (Enho) and plays a critical role in the regulation of lipid metabolism, insulin sensitivity, and endothelial function. Little is known of the effects of adropin in the brain and whether this peptide modulates ischemia-induced blood-brain barrier (BBB) injury. Here, we used an in vitro BBB model of rat brain microvascular endothelial cells (RBE4) and hypothesized that adropin would reduce endothelial permeability during ischemic conditions. To mimic ischemic conditions in vitro, RBE4 cell monolayers were subjected to 16h hypoxia/low glucose (HLG). This resulted in a significant increase in paracellular permeability to FITC-labeled dextran (40kDa), a dramatic upregulation of vascular endothelial growth factor (VEGF), and the loss of junction proteins occludin and VE-cadherin. Notably, HLG also significantly decreased Enho expression and adropin levels. Treatment of RBE4 cells with synthetic adropin (1, 10 and 100ng/ml) concentration-dependently reduced endothelial permeability after HLG, but this was not mediated through protection to junction proteins or through reduced levels of VEGF. We found that HLG dramatically increased myosin light chain 2 (MLC2) phosphorylation in RBE4 cells, which was significantly reduced by adropin treatment. We also found that HLG significantly increased Rho-associated kinase (ROCK) activity, a critical upstream effector of MLC2 phosphorylation, and that adropin treatment attenuated that effect. These data indicate that treatment with adropin reduces endothelial cell permeability after HLG insult by inhibition of the ROCK-MLC2 signaling pathway. These promising findings suggest that adropin protects against endothelial barrier dysfunction during ischemic conditions.

A possible connection between tumor necrosis factor alpha and adropin levels in polycystic ovary syndrome

CONTEXT

Adropin is a peptide hormone implicated in the regulation of insulin sensitivity and energy homeostasis. Polycystic ovary syndrome (PCOS) is a metabolic and reproductive disease associated with insulin resistance. It has been demonstrated that various inflammatory markers increased in PCOS including TNF-α. TNF-α regulates the secretion of certain peptides which play a crucial role in glucose and lipid homeostasis. There is also some evidence of a link between TNF-α and adropin.

OBJECTIVE

To ascertain whether there is an association between circulating adropin levels and TNF-α in PCOS.

PATIENTS AND DESIGN

152 women with PCOS and 152 age- and body mass index-matched controls without PCOS were recruited for this cross-sectional study.

MAIN OUTCOME MEASURES

Adropin and TNF-α levels were measured using ELISA.

RESULTS

Adropin levels were lower in the PCOS group compared with the control group (7.43 ± 0.79 vs. 9.42 ± 0.76 ng/ml, P < 0.001), whereas TNF-α levels were higher (49.93 ± 3.39 vs. 35.83 ± 2.47 pg/ml, P < 0.001). A strongly negative correlation was found between circulating adropin levels and TNF-α levels in women with PCOS (r = -0.407, P < 0.001). Binary logistic regression analysis revealed that decreased adropin levels were significantly associated with high odds of having PCOS, although, after adjustment for TNF-α, this link vanished. Additionally, multiple linear regression analysis showed that HOMA-IR and TFN-α independently predicted adropin levels.

CONCLUSIONS

Serum adropin levels are significantly decreased in PCOS and are inversely associated with TNF-α. Further dissection of the nature of this association can open new therapeutic options for metabolic diseases.

Potential Roles of Adropin in Central Nervous System: Review of Current Literature

Adropin is a 4.9 kDa peptide that is important for maintenance of metabolic and non-metabolic homeostasis. It regulates glucose and fatty acid metabolism and is involved in endothelial cell function and endothelial nitric oxide (NO) synthase bioactivity as well as physical activity and motor coordination. Adropin is expressed in many tissues and organs including central nervous system (CNS). This peptide plays a crucial role in the development of various CNS disorders such as stroke, schizophrenia, bipolar disorder as well as Alzheimer's, Parkinson's, and Huntington's diseases. In this comprehensive review, the potential roles of adropin in cellular signaling pathways that lead to pathogenesis and/or treatment of CNS disorders will be discussed.

Adropin as a potential marker of enzyme-positive acute coronary syndrome

Aim

Enzyme-positive acute coronary syndrome (EPACS) can cause injury to or death of the heart muscle owing to prolonged ischaemia. Recent research has indicated that in addition to liver and brain cells, cardiomyocytes also produce adropin. We hypothesised that adropin is released into the bloodstream during myocardial injury caused by acute coronary syndrome (ACS), so serum and saliva levels rise as the myocytes die. Therefore, it could be useful to investigate how ACS affects the timing and significance of adropin release in human subjects

Methods

Samples were taken over three days after admission, from 22 EPACS patients and 24 age- and gendermatched controls. The three major salivary glands (submandibular, sublingual and parotid) were immunohistochemically screened for adropin production, and serum and saliva adropin levels were measured by an enzyme-linked immunosorbent assay (ELISA). Salivary gland cells produce and secrete adropin locally.

Results

Serum adropin, troponin I, CK and CK-MB concentrations in the EPACS group became gradually higher than those in the control group up to six hours (p < 0.05), and troponin I continued to rise up to 12 hours after EPACS. The same relative increase in adropin level was observed in the saliva. Troponin I, CK and CK-MB levels started to decrease after 12 hours, while saliva and serum adropin levels started to decrease at six hours after EPACS. In samples taken four hours after EPACS, when the serum adropin value averaged 4.43 ng/ml, the receiver operating characteristic curve showed that the serum adropin concentration indicated EPACS with 91.7% sensitivity and 50% specificity, while when the cut-off adropin value in saliva was 4.12 ng/ml, the saliva adropin concentration indicated EPACS with 91.7% sensitivity and 57% specificity.

Conclusion

In addition to cardiac troponin and CK-MB assays, measurement of adropin level in saliva and serum samples is a potential marker for diagnosing EPACS.

Serum vascular endothelial growth factor receptor-2 and adropin levels in age-related macular degeneration

AIM

To investigate the serum levels of vascular endothelial growth factor receptor-2 (VEGFR-2) and adropin in age-related macular degeneration (AMD) patients.

METHODS

Ninety-eight AMD patients were included in the study. Seventy-eight age- and sex-matched healthy volunteers were recruited as the control group. Fundus florescein angiography and optical coherence tomography were performed to assess the posterior segment details. Serum VEGFR-2 and adropin levels were measured using enzyme-linked immunosorbent assays and compared between the study groups.

RESULTS

AMD group had significantly increased foveal retinal thickness, serum LDL and HDL levels and significantly decreased subfoveal choroidal thickness (P =0.01, 0.047, 0.025 and <0.001, respectively). Serum VEGFR-2 level revealed a significant decrease in AMD patients compared to controls (26.48±6.44 vs 30.42±7.92 ng/mL, P<0.001). There was an insignificant increase in serum adropin level in AMD patients (6.17±3.19 vs 5.79±2.71 ng/mL, P=0.4). Serum level of VEGFR-2 in AMD patients had a significant negative correlation with foveal retinal thickness (r=-0.226, P=0.025) and a significant positive correlation with subfoveal choroidal thickness (r=0.2, P=0.048).

CONCLUSION

The current study demonstrated that the decreased serum VEGFR-2 level may be considered in the development of AMD. Adropin does not seem to play a role in the pathogenesis of AMD.

Neuroprotective effect of ischemic preconditioning via modulating the expression of adropin and oxidative markers against transient cerebral ischemia in diabetic rats

INTRODUCTION

Ischemic preconditioning (IPreC) can render the brain more tolerant to a subsequent potential lethal ischemic injury. Hyperglycemia has been shown to increase the size of ischemic stroke and worsen the clinical outcome following a stroke, thus exacerbating oxidative stress. Adropin has a significant association with cardiovascular disease, especially with diabetes. In this study, we aimed to evaluate the role of the IPreC due to modulating the expression of adropin and oxidative damage markers against stroke by induced transient middle cerebral artery occlusion (MCAo) in streptozotocin (STZ)-induced diabetic rats.

MATERIAL-METHOD

72 male Spraque Dawley rats were allocated to 8 groups. In order to evaluate alterations of anti/oxidative status and adropin level, we induced transient MCAo seven days after STZ-induced diabetes. Also we performed IPreC 72h before transient MCAo to assess whether IPreC could have a neuroprotective effect against ischemia-reperfusion injury.

RESULTS

The general characteristics of STZ-treated rats (STZ) included reduced body weight and elevated blood glucose levels compared to non-diabetic ones. Ischemic preconditioning before cerebral ischemia significantly reduced infarction size compared with the other groups [IPreC+MCAo (27±11mm(3)) vs. MCAo (109±17mm(3)) p<0.001; STZ+IPreC+MCAo (38±10mm(3)) vs. STZ+MCAo (165±45mm(3)) p<0.001, respectively]. The mean total antioxidant status level in IPreC groups was higher than other groups (p≤0.05). Moreover, IPreC considerably decreased mean adropin levels compared with other groups (p≤0.05).

CONCLUSION

The study results supported the neuroprotective effects of ischemic preconditioning in MCA infarcts correlated with the level of oxidative damage markers and adropin.

Serum adropin level and ENHO gene expression in systemic sclerosis

Adropin, a secreted protein, is encoded by the energy homeostasis associated (ENHO) gene. It has been implicated in the several physiological and pathological processes such as angiogenesis and apoptosis. Therefore, the aim of present study was to investigate serum adropin levels and ENHO gene expressions in systemic sclerosis (SSc) characterized by vasculopathy, inflammation, and progressive fibrosis of the skin and internal organs. The study includes 27 patients with SSc, 39 patients with Behçet's disease (BD), and 20 healthy controls (HC). Serum adropin levels and ENHO gene expressions by peripheral blood mononuclear cells were analyzed by ELISA method and by real-time PCR, respectively. The serum adropin levels were higher in the SSc and BD groups than in the HC group (p = 0.023 and p < 0.001, respectively). However, there were no significant differences among the groups in terms of ENHO gene expressions (p ANOVA = 0.149). There was no significant difference between the limited and diffuse cutaneous subtypes of SSc in terms of serum adropin level and ENHO gene expression. Moreover, serum adropin level and ENHO gene expression were not associated with the disease activity and severity indexes. ENHO gene expression was correlated with the triglyceride levels in the BD group (r = -0.426, p = 0.027). The augmented serum adropin levels may be expected in the chronic inflammatory disease and seem not to be characteristic of only SSc. However, further studies are needed to explain the precise role of adropin in SSc.

Adropin levels and target organ damage secondary to high blood pressure in the ED

BACKGROUND

High blood pressure is still a challenge for emergency physicians to discern the patients that require further analysis to establish the existence of acute hypertensive target organ damage (TOD). The present study aimed to reveal that adropin levels are useful for detecting TOD in patients presenting with high blood pressure.

METHODS

Patients presenting with a blood pressure of more than 180/110 mm Hg were enrolled into the study. After a resting period of 15 minutes, patients' blood pressures were measured thrice at 5-minute intervals while the patients were sitting on a chair, and the average of these measurements was accepted as the baseline value. Blood samples were obtained for either adropin levels or possible TOD during the emergency department admission.

RESULTS

A total of 119 patients were included in the study. The mean systolic and diastolic blood pressures of study patients were 204.8±23.2 and 108.3 ± 10.3, respectively, and 42% (n = 50) of the patients had TOD. Although the adropin levels were similar between the patients with or without TOD (TOD group = 195 pg/mL, interquartile range [IQR]: 178-201; no-TOD group = 196 pg/mL, IQR: 176-204 [P = .982]), it is significantly higher in normotensive patients (normotensive group = 289 pg/mL, IQR: 193-403) compared with the hypertensive ones (P < .001).

CONCLUSIONS

Despite the significantly higher levels of adropin in normotensive patients compared with hypertensive ones, adropin could not be used as a decision tool for detecting TOD in patients presenting with high blood pressure to the emergency department.

Molecular cloning, characterization and expression of the energy homeostasis-associated gene in piglet

The energy homeostasis-associated (Enho) gene encodes a secreted protein, adropin, which regulates the expression of hepatic lipogenic genes and adipose tissue peroxisome proliferator-activated receptor γ, a major regulator of lipogenesis. In the present study, the porcine (Sus scrofa) homologue of the Enho gene, which was named pEnho, was amplified by reverse transcriptase polymerase chain reaction (RT-PCR) using oligonucleotide primers derived from in silico sequences. The gene sequence was submitted into the GenBank of NCBI, and the access number is GQ414763. The pEnho encodes a protein of 76 amino acids which shows 75% similarity to Homo sapiens adropin. The expression profile of pEnho in tissues (liver, muscle, anterior jejunum, posterior jejunum, and ileum) was determined by quantitative real-time RT-PCR. pEnho was localized on porcine chromosome 10 and no introns were found. In conclusion, pEnho was cloned and analysed with the aim of increasing knowledge about glucose and lipid metabolism in piglets and helping to promote the health and growth of piglets through adropin regulation.

Plasma adropin level in patients with pseudoexfoliation

The aim of this study was to evaluate plasma adropin levels in patients with pseudoexfoliation (PEX). This retrospective case-control study included 35 patients with PEX and 35 individuals without PEX who served as controls. Plasma adropin levels with triglycerides, total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and haemoglobin A1c (HGBA1C) concentrations were measured in both groups. The mean serum adropin levels were 3.24 ± 0.95 ng/mL (range, 1.90-7.88 ng/mL) in patients with PEX syndrome and 5.78 ± 2.85 ng/mL (range, 2.08-5.41 ng/mL) in PEX glaucoma patients. There was no statistically significant difference in mean adropin levels between PEX syndrome and PEX glaucoma patients. However, similar adropin levels were found in the PEX glaucoma patients and the control group (P > 0.05). The mean serum adropin levels were 3.34 ± 0.89 ng/mL (range, 1.90-5.39 ng/mL) in the PEX group and 5.78 ± 2.85 ng/mL (range, 3.08-11.06 ng/mL) in the control group. The mean serum adropin level of the PEX group was significantly lower than that of the control group (P < 0.001). There were no significant differences between the two groups in terms of serum glucose, total cholesterol, LDL, HDL, HGBA1C, triglycerides levels, or body mass index (all P > 0.05). Adropin level is lower in patients with PEX.

Adropin is associated with hyperhomocysteine and coronary atherosclerosis

Homocysteine has been recognized as a risk factor for atherosclerosis and cardiovascular diseases. Adropin is a newly-identified energy homeostasis protein with a potential protective effect against coronary artery disease (CAD). This study attempted to measure the correlation between serum homocysteine and adropin levels in patients with CAD, and to ascertain how the two hormones could affect the severity of coronary atherosclerosis. A cohort of CAD patients who had undergone coronary angiography was prospectively recruited. The serum homocysteine and adropin levels of the patients were measured and the severity of coronary atherosclerosis was quantified with the SYNTAX score. The data were analyzed with a generalized structural equation model. In total, 170 consecutive patients were recruited with a mean serum homocysteine level of 15.9±8.3 µmol/l, and 76 (44.7%) patients were identified as hyperhomocysteinemic with a serum homocysteine level >15 µmol/l. Serum homocysteine level was found to be significantly negatively correlated with serum adropin level (r=-0.169, P=0.028). Patients with hyperhomocysteinemia had lower serum adropin levels and higher SYNTAX scores than patients without hyperhomocysteinemia. Further analysis with a generalized structural equation model showed that adropin was significantly associated with hyperhomocysteinemia (adjusted odds ratio: 0.95, 95% confidence interval: 0.93 to 0.98; P=0.002), which in turn was significantly associated with the SYNTAX score (coefficient: 4.71, 95% confidence interval: 1.39 to 8.03; P=0.005). In conclusion, the serum homocysteine level was inversely correlated with the serum adropin level in patients with CAD. A low serum adropin level was associated with hyperhomocysteinemia and more severe coronary atherosclerosis, as reflected by a higher SYNTAX score.

Inverse Correlation Between Plasma Adropin and ET-1 Levels in Essential Hypertension: A Cross-Sectional Study

Adropin is a recently identified bioactive protein that promotes energy homeostasis by affecting glucose and lipid metabolism. Recently, adropin has also been reported to be associated with endothelial dysfunction. Also, ET-1, as a biomarker for endothelial dysfunction, is a key regulator in hypertension. Accordingly, the aim of the present study was to detect the relationship between plasma adropin and ET-1 levels in hypertension. A total of 123 participants, diagnosed with primary hypertension on the basis of World Health Organization criteria (systolic blood pressure [SBP] ≥ 140 mmHg and/or diastolic blood pressure (DBP) ≥ 90 mmHg), and 58 normotensive subjects were enrolled in the cross-sectional study from October 2011 to December 2013. All study participants were older than 18 years of age. Adropin and ET-1 levels were measured by enzyme-linked immunosorbent assay (ELISA). We found that plasma adropin levels were significantly lower in hypertensives compared with controls (3.18 ± 1.00 vs 4.21 ± 1.14 ng/mL, P < 0.001). Plasma ET-1 levels were higher in hypertensives than controls (2.60 ± 1.14 vs 1.54 ± 0.66 pg/mL, P < 0.001). Adropin had a negative correlation with DBP (r = -0.40, P < 0.001), SBP (r = -0.49, P < 0.001), and adjusted for age, body mass index, SBP, DBP, glucose, TC, TG, LDL, and Cr, there was a negative correlation between ET-1 and adropin (r = -0.20, P = 0.04). In multivariate logistic regression analysis of the variables, ET-1 (odds ratio [OR], 3.84; 95% CI, 2.16-6.81; P < 0.001) and adropin (OR, 0.99; 95% CI, 0.99 -1.0; P <  .001) were found to be independent predictors for hypertension.In conclusion, decreased plasma adropin levels are associated with increased blood pressure in hypertension. Adropin is an independent predictor for hypertension, and may influence blood pressure by protecting endothelial function.