Adropin deficiency is associated with increased adiposity and insulin resistance

Unveiling the multifaceted role of adropin in various diseases (Review)

Adropin is a secreted peptide encoded by the energy homeostasis‑associated gene, which also functions as a membrane‑bound protein facilitating intercellular communication. This peptide has been detected in various tissues and body fluids, including the brain, liver, kidney, heart, pancreas, small intestine, endothelial cells and colostrum. Notably, the amino acid sequences of adropin are identical in humans, mice and rats. Previous studies have demonstrated that adropin levels fluctuate under different physiological and pathological conditions. Adropin plays a role in regulating carbohydrate metabolism, lipid metabolism and intercellular molecular signaling pathways, implicating its involvement in the progression of numerous diseases, such as acute myocardial infarction, lung injury, non‑alcoholic fatty liver disease/non‑alcoholic steatohepatitis, kidney disease, polycystic ovary syndrome, obesity, and diabetes, atherosclerosis, systemic sclerosis and cancer. Despite its significance, the precise role and mechanism of this protein remain inadequately understood and studied. To elucidate the function of adropin and its clinical research status, a systematic review of recent studies on adropin across various diseases was conducted. Additionally, several challenges and limitations associated with adropin research in both animal and clinical contexts were identified, aiming to offer valuable insights for future investigation.

The Evaluation of Adropin and Autotaxin as Potential Markers of Endothelial Dysfunction in Preeclampsia

Endothelial dysfunction (ED) plays a prominent role in the pathogenesis of preeclampsia (PE). There is a need for non-invasive methods to assess endothelial function in preeclamptic patients. In the present study, adropin, autotaxin (ATX), and lysophosphatidic acid (LPA) were evaluated as indicators of ED. Patients diagnosed with PE and healthy pregnant women (n = 42 for each group) were compared. After measuring flow-mediated dilation (FMD), the participants were stratified as ED (+) or ED (-) based on a cut-off value of 6.5%. The PE patients were divided as early/late onset PE and severe/mild PE. Adropin, ATX, and LPA levels were measured, and their relevance to ED was evaluated. Student t, Mann-Whitney U, or ANOVA tests were used for statistics, as appropriate. Adropin levels were diminished in the ED (+) group, whereas ATX and LPA levels were increased. The decrease in adropin levels was more pronounced in severe PE, showing a positive correlation with the FMD. In the logistic regression model, adropin was the only parameter that was an independent variable for the FMD test (P < .001). Adropin measurements in serum may be of value for disease follow-up in patients with PE.

Adropin may regulate ovarian functions by improving antioxidant potential in adult mouse

The corpus luteum (CL) is a temporary endocrine gland that synthesizes progesterone. The luteal progesterone plays a central role in the regulation of the estrous cycle as well as the implantation and maintenance of pregnancy. Our previous study showed the expression of adropin and its receptor, GPR19, in the luteal cells and its significant role in luteinization. The aim of the present study was to investigate the in vitro effect of adropin on hCG-induced ovarian functions in adult mice. We also evaluated the effect of exogenous treatment with adropin on ovarian steroidogenesis and anti-oxidant parameters, with special emphasis on CL function. Our results demonstrated that adropin acts synergistically with hCG to promote ovarian steroidogenesis and survival by increasing the expression of StAR, 3β-HSD, and aromatase proteins and decreasing the BAX/BCL2 ratio. Exogenous adropin treatment increased progesterone production by increasing the expression of GPR19, StAR and 3β-HSD enzymes in the mouse ovary. Also, adropin inhibited the luteal oxidative stress by increasing nuclear translocation of NRF-2 in CL, which resulted in increased HO-1 expression and SOD, catalase activity. Decreased oxidative stress might inhibit the translocation of NF-κB into the nucleus of luteal cells, resulting into increased survival and decreased apoptosis, as evident by decreased lipid peroxidation, BAX/BCL2 ratio, caspase 3, active caspase 3 expression, and TUNEL-positive cells in adropin treated mice. Our findings suggest that adropin can be a promising candidate that can enhance the survivability of the CL.

Hepatokines: unveiling the molecular and cellular mechanisms connecting hepatic tissue to insulin resistance and inflammation

Insulin resistance arising from Non-Alcoholic Fatty Liver Disease (NAFLD) stands as a prevalent global ailment, a manifestation within societies stemming from individuals' suboptimal dietary habits and lifestyles. This form of insulin resistance emerges as a pivotal factor in the development of type 2 diabetes mellitus (T2DM). Emerging evidence underscores the significant role of hepatokines, as hepatic-secreted hormone-like entities, in the genesis of insulin resistance and eventual onset of type 2 diabetes. Hepatokines exert influence over extrahepatic metabolism regulation. Their principal functions encompass impacting adipocytes, pancreatic cells, muscles, and the brain, thereby playing a crucial role in shaping body metabolism through signaling to target tissues. This review explores the most important hepatokines, each with distinct influences. Our review shows that Fetuin-A promotes lipid-induced insulin resistance by acting as an endogenous ligand for Toll-like receptor 4 (TLR-4). FGF21 reduces inflammation in diabetes by blocking the nuclear translocation of nuclear factor-κB (NF-κB) in adipocytes and adipose tissue, while also improving glucose metabolism. ANGPTL6 enhances AMPK and insulin signaling in muscle, and suppresses gluconeogenesis. Follistatin can influence insulin resistance and inflammation by interacting with members of the TGF-β family. Adropin show a positive correlation with phosphoenolpyruvate carboxykinase 1 (PCK1), a key regulator of gluconeogenesis. This article delves into hepatokines' impact on NAFLD, inflammation, and T2DM, with a specific focus on insulin resistance. The aim is to comprehend the influence of these recently identified hormones on disease development and their underlying physiological and pathological mechanisms.

Methods to predict heart failure in diabetes patients

INTRODUCTION

Type 2 diabetes mellitus (T2DM) is one of the leading causes of cardiovascular disease and powerful predictor for new-onset heart failure (HF).

AREAS COVERED

We focus on the relevant literature covering evidence of risk stratification based on imaging predictors and circulating biomarkers to optimize approaches to preventing HF in DM patients.

EXPERT OPINION

Multiple diagnostic algorithms based on echocardiographic parameters of cardiac remodeling including global longitudinal strain/strain rate are likely to be promising approach to justify individuals at higher risk of incident HF. Signature of cardiometabolic status may justify HF risk among T2DM individuals with low levels of natriuretic peptides, which preserve their significance in HF with clinical presentation. However, diagnostic and predictive values of conventional guideline-directed biomarker HF strategy may be non-optimal in patients with obesity and T2DM. Alternative biomarkers affecting cardiac fibrosis, inflammation, myopathy, and adipose tissue dysfunction are plausible tools for improving accuracy natriuretic peptides among T2DM patients at higher HF risk. In summary, risk identification and management of the patients with T2DM with established HF require conventional biomarkers monitoring, while the role of alternative biomarker approach among patients with multiple CV and metabolic risk factors appears to be plausible tool for improving clinical outcomes.

Nutrient patterns in relation to metabolic health status and serum levels of brain-derived neurotrophic factor (BDNF) and adropin in adults

The present study aimed to investigate the association of nutrient patterns (NPs) with metabolic health status and serum levels of brain-derived neurotrophic factor (BDNF) and adropin in Iranian adults. This cross-sectional survey was performed on 527 adults aged 20-60 years in Isfahan, Iran. To evaluate dietary intake, a validated 168-item semi-quantitative food frequency questionnaire (FFQ) was used. Participants were categorized as metabolically healthy (MH) and metabolically unhealthy (MU) according to their glycemic and lipid profile, insulin resistance (IR), and inflammation status. An overnight fasting blood sample was collected from each participant and serum levels of BDNF and adropin were assessed. A total of 42.50% of participants were recognized as MU. Three NPs were recognized by factor analysis that labeled as "high animal protein" (NP1), "high vegetable" (NP2), and "high carbohydrate" (NP3) patterns. Moderate adherence to NP2 was related to a lower risk of MU (ORT2 vs. T1 = 0.38, 95% CI: 0.18-0.76). Moreover, high adherence of NP2 (T3 vs. T1) was inversely associated with hypertriglyceridemia (OR = 0.27, 95% CI: 0.11-0.65; P-trend < 0.001) and high hs-CRP values (OR = 0.29, 95% CI: 0.09-1.00; P-trend = 0.03). No significant association was observed between adherence of NP1 and NP3 with MU in crude and adjusted models. However, negative associations were found between moderate adherence to NP3 and insulin resistance (IR) (OR = 0.23, 95% CI: 0.06-0.91) as well as high adherence to NP1 and hypertension (OR = 0.23, 95% CI: 0.09-0.61; P-trend < 0.001). NPs were not associated with serum BDNF and adropin values.

Adropin may promote insulin stimulated steroidogenesis and spermatogenesis in adult mice testes

Adropin is a versatile peptide which was discovered as a novel metabolic hormone that is involved in the regulation of lipid and glucose homeostasis. However, its possible role in the testicular function is not yet understood. The aim of our study was to explore the distribution pattern of adropin and GPR19 in various cell types and its possible role in testicular functions of adult mice. Immunohistochemical study revealed the intense immunoreactivity of adropin in the Leydig cells, while GPR19 showed intense immunoreactivity in the pachytene spermatocytes and mild immunoreactivity in Leydig cells and primary as well as secondary spermatocytes in mouse testis. Enho mRNA was also found to be expressed in the mouse testis. These findings suggested that adropin-GPR19 signaling may act in autocrine/paracrine manner to modulate testicular functions. Furthermore, to find out the direct role of adropin in the testicular function, in vitro study was performed in which testicular slices were cultured with adropin alone (10 and 100 ng/mL) and in combination with insulin (5 μg/mL). Adropin alone inhibited testicular testosterone synthesis by inhibiting the expression of P450-SCC, 3β-HSD, and 17β-HSD while along with insulin stimulated the testicular testosterone synthesis by increasing the expression of GPR19, IR, StAR, P450-SCC, 3β-HSD, and 17β-HSD. Adropin alone or in combination with insulin promoted germ cell survival and proliferation by upregulating the expression of PCNA, Bcl2, and pERK1/2. Thus, it can be concluded that adropin-GPR19 signaling promotes insulin stimulated steroidogenesis and germ cell survival as well as proliferation in the mice testes in an autocrine/paracrine manner.

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.

Ontogeny of adropin and its receptor expression during postnatal development and its pro-gonadal role in the ovary of pre-pubertal mouse

Adropin, a highly conserved multifunctional peptide hormone, has a beneficial effect on the maintenance of gluco-lipid homeostasis, endothelial and cardiovascular functions. However, the expression and potential role of adropin in ovarian function are not fully elucidated. The present study aimed to investigate the expression of adropin and GPR19 in the mice ovary during various stages of postnatal development. This study also explored whether the treatment of adropin can modulate the timing of puberty, for which pre-pubertal mice were treated with adropin. The result showed the intense immunoreactivity of adropin in TICs, while GPR19 immunoreactivity was noted in GCs in infantile, pre-pubertal, and pubertal mice ovary. Also, adropin and GPR19 are highly expressed in the CL of the ovary of reproductively active mice. The fact that adropin expression in the ovary at different stages of postnatal development positively correlated with circulating progesterone and estradiol indicated that it has a role in the production of steroid hormones. Furthermore, the results of in vivo studies in pre-pubertal mice showed that adropin promotes early folliculogenesis by enhancing the proliferation (PCNA) of GCs of cortical ovarian follicles and promotes estradiol production by enhancing the expression of GPR19, StAR, CYP11A1 and aromatase proteins. Also, adropin treatment increases the Bax/Bcl2 ratio and expression of cleaved caspase-3 and ERα proteins, which may result in increased apoptosis of medullary follicles leading to the formation of a well-developed interstitium with interstitial glandular cells. Collectively, these findings indicate that adropin may be a factor that accelerates pubertal development in the ovary and could be utilized as a therapeutic approach for treating pubertal delay.

Adropin inhibits the progression of atherosclerosis in ApoE-/-/Enho-/- mice by regulating endothelial-to-mesenchymal transition

Adropin, a secreted protein, coded by energy homeostasis-associated gene (Enho), is recently reported to modulate atherogenesis, with endothelial-to-mesenchymal transition (EndMT) involved in the early process. We explored whether adropin may alleviate atherosclerosis by regulating EndMT. We found that an intraperitoneal injection of adropin [105 μg/(kg·d) for 13 weeks] inhibited the progression of high-fat diet (HFD)-induced aortic atherosclerosis in apolipoprotein E-deficient mice (ApoE-/-) and those with double gene deletion (ApoE-/-/Enho-/-), as detected by Oil Red O and haematoxylin-eosin staining. In the aortas of ApoE-/- mouse, adropin treatment ameliorated the decrease in the mRNA expression of endothelial cell markers (leukocyte differentiation antigen 31, CD31, and vascular endothelial cadherin, VE-cadherin), but increased that of EndMT markers (alpha smooth muscle actin, α-SMA, and fibroblasts specific protein-1). In vitro, an adropin treatment (30 ng/ml) arrested the hydrogen peroxide (H2O2)-induced EndMT in human umbilical vein endothelial cells (HUVECs), attenuated the morphological changes of HUVECs, reduced the number of immunofluorescence-positive α-SMA, increased the mRNA and protein expressions of CD31 and VE-cadherin, and decreased those of α-SMA. Furthermore, the adropin treatment decreased the mRNA and protein expressions of transforming growth factor (TGF)-β1 and TGF-β2, and suppressed the phosphorylation of downstream signal protein Smad2/3 in HUVECs. These mitigative effects of adropin on H2O2-induced EndMT were reversed by the transfection of TGF-β plasmid. The findings signify that adropin treatment may alleviate the atherosclerosis in ApoE-/-/Enho-/- mice by inhibiting EndMT via the TGF-β/Smad2/3 signaling pathway.

Clinical Significance of Adropin and Afamin in Evaluating Renal Function and Cardiovascular Health in the Presence of CKD-MBD Biomarkers in Chronic Kidney Disease

AIM

The study aims to test the hypothesis that concentrations of adropin and afamin differ between patients in various stages of chronic kidney disease when compared with healthy controls. The study also investigates the association of the biomarkers (adropin and afamin) with CKD-MBD and traditional cardiovascular risk parameters in CKD patients.

METHODOLOGY

The cross-sectional study includes the subjects divided into four groups comprising the control group (healthy volunteers = 50), CKD stages 1-2 patients (n = 50), CKD stages 3-4 patients (n = 50), CKD stage 5 patients (n = 50). Serum concentrations of adropin and afamin were determined using ELISA. Clinical variables (renal, lipid, and CKD-MBD parameters) were correlated to adropin and afamin concentrations.

RESULTS

Afamin concentration was found to be higher in group IV, followed by groups III and II when compared to the control group, i.e., (83.243 ± 1.46, 64.233 ± 0.99, and 28.948 ± 0.72 vs. 14.476 ± 0.5) mg/L (p < 0.001), and adropin concentration was found to be lower in group IV as compared to groups III, II, and I (200.342 ± 8.37 vs. 284.682 ± 9.89 vs. 413.208 ± 12.32 vs. 706.542 ± 11.32) pg/mL (p < 0.001), respectively. Pearson correlation analysis showed that afamin was positively correlated with traditional cardiovascular risk biomarkers, while adropin showed a negative correlation.

CONCLUSIONS

Adropin and afamin may potentially serve as futuristic predictors for the deterioration of renal function and may be involved in the pathological mechanisms of CKD and its associated complications such as CKD-MBD and high lipid levels.

Serum Adropin Levels and Body Mass Composition in Kidney Transplant Recipients-Are There Sex Differences?

Adropin is a secretory peptide that regulates glucose, lipid, and protein metabolism, which is closely related to obesity, insulin resistance, dyslipidemia, and atherogenesis. The serum adropin level is related to sex and depends upon nutritional preferences. This study aims to determine the association between serum adropin levels and body composition parameters in kidney transplant recipients (KTRs), especially emphasizing sex differences. Our case-control study involved 59 KTRs (28 postmenopausal women and 31 men) who were divided into two groups according to sex, and each group of those KTRs was further divided into higher or lower adropin values than the mean value in each sex group. Univariate regression showed a negative association of adropin levels with most anthropometric and body composition parameters in men's KTRs. Contrary to this, the serum adropin level was negatively associated only with phase angle in postmenopausal female KTRs. Multivariate regression showed that skeletal muscle mass and phase angle were the only negative predictors in women's KTRs, whereas in men, negative predictors were BMI and body water. These findings imply that adropin could have a different impact on metabolic homeostasis in KTRs regarding sex and could be considered a negative predictor of body composition in KTRs.

Recent progress in understanding mitokines as diagnostic and therapeutic targets in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent tumors worldwide and the leading contributor to cancer-related deaths. The progression and metastasis of HCC are closely associated with altered mitochondrial metabolism, including mitochondrial stress response. Mitokines, soluble proteins produced and secreted in response to mitochondrial stress, play an essential immunomodulatory role. Immunotherapy has emerged as a crucial treatment option for HCC. However, a positive response to therapy is typically dependent on the interaction of tumor cells with immune regulation within the tumor microenvironment. Therefore, exploring the specific immunomodulatory mechanisms of mitokines in HCC is essential for improving the efficacy of immunotherapy. This study provides a comprehensive overview of the association between HCC and the immune microenvironment and highlights recent progress in understanding the involvement of mitochondrial function in preserving liver function. In addition, a systematic review of mitokines-mediated immunomodulation in HCC is presented. Finally, the potential diagnostic and therapeutic roles of mitokines in HCC are prospected and summarized. Recent progress in mitokine research represents a new prospect for mitochondrial therapy. Considering the potential of mitokines to regulate immune function, investigating them as a relevant molecular target holds great promise for the diagnosis and treatment of HCC.

Longitudinal changes in serum adropin levels and liver fat content during liraglutide treatment in newly diagnosed patients with type 2 diabetes mellitus and metabolic dysfunction-associated fatty liver disease

AIMS

To explore the effect of liraglutide treatment on serum adropin and its relationship to the liver fat content in newly diagnosed patients with type 2 diabetes mellitus (T2DM) and metabolic dysfunction-associated fatty liver disease (MAFLD).

METHODS

Serum adropin level and liver fat content were assessed in patients with T2DM and MAFLD (n = 22), along with healthy controls (n = 22). Afterward, the patients received liraglutide treatment for 12 weeks. Serum adropin levels were examined by a competitive enzyme-linked immunosorbent assay. Liver fat content was quantified via magnetic resonance imaging-estimated proton density fat fraction (MRI-PDFF).

RESULTS

We found that patients with newly diagnosed T2DM and MAFLD had lower serum adropin levels [2.79 ± 0.47 vs. 3.27 ± 0.79 ng/mL, P < 0.05] and higher liver fat content [19.12 ± 9.46 vs. 4.67 ± 0.61%, P < 0.001], compared to healthy controls. Following 12-week liraglutide treatment, serum adropin levels increased from 2.83(2.44, 3.24) to 3.65(3.20, 3.85) ng/mL (P < 0.001), and liver fat content decreased from 18.04(11.08, 27.65) to 7.74(6.42, 13.49) % (P < 0.001) in patients with T2DM and MAFLD. Furthermore, increases in serum adropin were strongly associated with decreases in liver fat content (β = - 5.933, P < 0.001), liver enzyme and glucolipid metabolism parameters.

CONCLUSION

The increase in serum adropin level following liraglutide treatment was strongly correlated with the reduction in liver fat content and glucolipid metabolism. Hence, adropin might be a potential marker for the beneficial effects of liraglutide on treating T2DM and MAFLD.

Circulating levels of adropin and diabetes: a systematic review and meta-analysis of observational studies

OBJECTIVE

Adropin, a newly identified regulatory protein has garnered attention given its potential role in metabolism regulation, especially glucose metabolism and insulin resistance. However, studies on the association between adropin and type 2 diabetes mellitus (T2DM) are equivocal. The aim of this study is to assess the association between serum adropin levels and T2DM using a systematic review and meta-analysis of observational studies.

METHODS

PubMed, Scopus, ISI Web of science, and Google Scholar were searched, up to August 2022, for studies that reported the association between serum levels of adropin in adults with T2DM compared to a control group without diabetes. A random-effect model was used to compute the pooled weighted mean difference (WMD) with 95% confidence intervals (CI).

RESULTS

Meta-analysis of 15 studies (n = 2813 participants) revealed that the serum adropin concentrations were significantly lower in patients with T2DM compared with the control group (WMD= -0.60 ng/mL, 95% CI: -0.70 to -0.49; I² = 99.5%). Subgroup analysis also found lower concentration of adropin in patients with T2DM who were otherwise healthy compared to a control group (n = 9; WMD=-0.04 ng/ml, 95% CI= -0.06 to -0.01, p = 0.002; I² = 96.4).

CONCLUSIONS

Our study showed adropin levels are lower in patients with diabetes compared to a control group without diabetes. However, the limitations of observational studies challenge the validity of the results, and further investigations are needed to confirm the veracity of these findings and additionally explore possible mechanisms.

The Impact of SGLT2 Inhibitor Dapagliflozin on Adropin Serum Levels in Men and Women with Type 2 Diabetes Mellitus and Chronic Heart Failure

BACKGROUND

adropin plays a protective role in cardiac remodeling through supporting energy metabolism and water homeostasis and suppressing inflammation. Low circulating levels of adropin were positively associated with the risk of cardiovascular diseases and type 2 diabetes mellitus (T2DM). We hypothesized that sodium-glucose linked transporter 2 (SGLT2) inhibitor dapagliflosin might represent cardiac protective effects in T2DM patients with known chronic HF through the modulation of adropin levels.

METHODS

we prospectively enrolled 417 patients with T2DM and HF from an entire cohort of 612 T2DM patients. All eligible patients were treated with the recommended guided HF therapy according to their HF phenotypes, including SGLT2 inhibitor dapagliflozin 10 mg, daily, orally. Anthropometry, clinical data, echocardiography/Doppler examinations, and measurements of biomarkers were performed at the baseline and over a 6-month interval of SGLT2 inhibitor administration.

RESULTS

in the entire group, dapagliflozin led to an increase in adropin levels by up to 26.6% over 6 months. In the female subgroup, the relative growth (Δ%) of adropin concentrations was sufficiently higher (Δ% = 35.6%) than that in the male subgroup (Δ% = 22.7%). A multivariate linear regression analysis of the entire group showed that the relative changes (Δ) in the left ventricular (LV) ejection fraction (LVEF), left atrial volume index (LAVI), and E/e' were significantly associated with increased adropin levels. In the female subgroup, but not in the male subgroup, ΔLVEF (p = 0.046), ΔLAVI (p = 0.001), and ΔE/e' (p = 0.001) were independent predictive values for adropin changes.

CONCLUSION

the levels of adropin seem to be a predictor for the favorable modification of hemodynamic performances during SGLT2 inhibition, independent ofN-terminal brain natriuretic pro-peptide levels.

Adropin and MOTS-c as new peptides: Do levels change in neurodegenerative diseases and ischemic stroke?

BACKGROUND

Neurological diseases such as Alzheimer's disease and Parkinson's disease (AD, PD), acute ischemic stroke (AIS), and multiple sclerosis (MS) are thought to be deeply affected by changes in the pathophysiological processes of neurons. As new peptides, it was aimed to evaluate the level of adropin and MOTS-c (mitochondrial open reading frame of the 12S rRNA-c) and its possible relationship with NSE (neuron-specific enolase) and NF-L (neurofilament light chain) in terms of neuronal interaction.

METHODS

This study was conducted with 32 patients from each subgroup and group-appropriate controls. Disease identifiers and hemogram/biochemical parameters specific to the groups of participants were obtained. Additionally, plasma adropin, MOTS-c, NSE, and NF-L levels were evaluated by the ELISA method.

RESULTS

Plasma adropin levels were decreased in the AD group and decreased in MOTS-c, AIS, and AD groups compared to the control (p < 0.05). Similar values were found in the MS group compared to its control (p > 0.05). In correlation analysis of these markers with laboratory parameters, while platelet and cholesterol levels were negatively correlated with adropin levels; platelet, lymphocyte, and triglyceride levels were positively correlated with MOTS-c (p < 0.05).

CONCLUSION

This study provides new information about adropin may be potentially important markers in AD and MOTS-C in AIS and AD. Future studies are needed to examine the relationship between changes in metabolic profiles and these peptides.

Exon-intron split analysis reveals posttranscriptional regulatory signals induced by high and low n-6/n-3 polyunsaturated fatty acid ratio diets in piglets

Polyunsaturated fatty acids (PUFA), such as omega-6 (n-6) and omega-3 (n-3), play a vital role in nutrient metabolism, inflammatory response, and gene regulation. microRNAs (miRNA), which can potentially degrade targeted messenger RNAs (mRNA) and/or inhibit their translation, might play a relevant role in PUFA-related changes in gene expression. Although differential expression analyses can provide a comprehensive picture of gene expression variation, they are unable to disentangle when in the mRNA life cycle the regulation of expression is taking place, including any putative functional miRNA-driven repression. To capture this, we used an exon-intron split analysis (EISA) approach to account for posttranscriptional changes in response to extreme values of n-6/n-3 PUFA ratio. Longissimus dorsi muscle samples of male and female piglets from sows fed with n-6/n-3 PUFA ratio of 13:1 (SOY) or 4:1 (LIN), were analyzed in a bidirectional contrast (LIN vs. SOY, SOY vs. LIN). Our results allowed the identification of genes showing strong posttranscriptional downregulation signals putatively targeted by significantly upregulated miRNA. Moreover, we identified genes primarily involved in the regulation of lipid-related metabolism and immune response, which may be associated with the pro- and anti-inflammatory functions of the n-6 and n-3 PUFA, respectively. EISA allowed us to uncover regulatory networks complementing canonical differential expression analyses, thus providing a more comprehensive view of muscle metabolic changes in response to PUFA concentration.

Association of plant-based diets with adropin, atherogenic index of plasma, and metabolic syndrome and its components: A cross-sectional study on adults

Background

Little is known about the association of plant-based diet indices with metabolic syndrome (MetS) and its novel predictive biomarkers, including the atherogenic index of plasma (AIP) and adropin. We aimed to investigate the association of plant-based diets with adropin, atherogenic index of plasma, and MetS and its components in adults.

Methods

The present population-based cross-sectional study was conducted on a representative sample of adults aged 20-60 years in Isfahan, Iran. Dietary intake was obtained through a validated 168-item semi-quantitative food frequency questionnaire (FFQ). Peripheral blood was obtained after an overnight fast of at least 12 h from each participant. MetS was identified based on the Joint Interim Statement (JIS). AIP was calculated as a logarithmically transformed ratio of triglyceride (TG)/high-density lipoprotein cholesterol (HDL-c), and serum levels of adropin were measured by an ELISA kit.

Results

A total of 28.7% of subjects had MetS. No significant association was found between the overall plant-based diet index (PDI) and the healthful plant-based diet index (hPDI) with MetS. However, a non-linear association was observed between hPDI and MetS. Subjects in the third quartile of the unhealthful plant-based diet index (uPDI) had higher odds of MetS compared to the first quartile (OR: 2.39; 95% CI: 1.01, 5.66). The highest quartile of PDI (OR: 0.46; 95% CI: 0.21, 0.97) and the third quartile of hPDI (OR: 0.40; 95% CI: 0.18, 0.89) were associated with decreased odds of having high-risk AIP compared to the first quartile, after adjusting for potential confounders. No linear association was found between quartiles of plant-based diet indices and serum levels of adropin.

Conclusion

Plant-based diet index (PDI) and hPDI were not associated with the prevalence of MetS in adults, while moderate adherence to uPDI increased the prevalence of MetS. In addition, high adherence to PDI and moderate adherence to hPDI were associated with decreased odds of high-risk AIP. No significant association was found between plant-based diet indices and serum adropin levels. To confirm these findings, further studies with prospective designs are warranted.

Therapeutic Benefits of Adropin in Aged Mice After Transient Ischemic Stroke via Reduction of Blood-Brain Barrier Damage

BACKGROUND

Adropin is a peptide encoded by the energy homeostasis-associated gene (Enho) that is highly expressed in the brain. Aging and stroke are associated with reduced adropin levels in the brain and plasma. We showed that treatment with synthetic adropin provides long-lasting neuroprotection in permanent ischemic stroke. However, it is unknown whether the protective effects of adropin are observed in aged animals following cerebral ischemia/reperfusion. We hypothesized that adropin provides neuroprotection in aged mice subjected to transient middle cerebral artery occlusion.

METHODS

Aged (18-24 months old) male mice were subjected to 30 minutes of middle cerebral artery occlusion followed by 48 hours or 14 days of reperfusion. Sensorimotor (weight grip test and open field) and cognitive tests (Y-maze and novel object recognition) were performed at defined time points. Infarct volume was quantified by 2,3,5-triphenyltetrazolium chloride staining at 48 hours or Cresyl violet staining at 14 days post-middle cerebral artery occlusion. Blood-brain barrier damage, tight junction proteins, and MMP-9 (matrix metalloproteinase-9) were assessed 48 hours after middle cerebral artery occlusion by ELISA and Western blots.

RESULTS

Genetic deletion of Enho significantly increased infarct volume and worsened neurological function, whereas overexpression of adropin dramatically reduced stroke volume compared to wild-type controls. Postischemic treatment with synthetic adropin peptide given at the onset of reperfusion markedly reduced infarct volume, brain edema, and significantly improved locomotor function and muscular strength at 48 hours. Delayed adropin treatment (4 hours after the stroke onset) reduced body weight loss, infarct volume, and muscular strength dysfunction, and improved long-term cognitive function. Postischemic adropin treatment significantly reduced blood-brain barrier damage. This effect was associated with reduced MMP-9 and preservation of tight junction proteins by adropin treatment.

CONCLUSIONS

These data unveil a promising neuroprotective role of adropin in the aged brain after transient ischemic stroke via reducing neurovascular damage. These findings suggest that poststroke adropin therapy is a potential strategy to minimize brain injury and improve functional recovery in ischemic stroke patients.

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.

Regulation of Adropin by Sitagliptin monotherapy in participants with newly diagnosed type 2 Diabetes

BACKGROUND

Adropin is a potent metabolic regulator of insulin sensitivity and glycolipid metabolism. The present study investigated the effects of sitagliptin on adropin and metabolic parameters in participants with newly diagnosed type 2 diabetes (T2D).

METHODS

Thirty-five participants newly-diagnosed with T2D were prescribed sitagliptin 100 mg once daily for 17 weeks. Twenty-eight age-, sex-, and BMI-matched healthy subjects were included as the control group. Adropin and clinical parameters were assessed at baseline and after treatment.

RESULTS

At baseline, serum adropin levels were lower in T2D participants than in the healthy individuals (3.12 ± 0.73 vs. 5.90 ± 1.22 ng/ml, P <  0.01). Serum adropin levels were significantly higher in T2D patients after sitagliptin treatment (4.97 ± 1.01 vs. 3.12 ± 0.73 ng/ml, P <  0.01). The changes in serum adropin levels after sitagliptin treatment were associated with the improvements of fasting blood glucose (FBG) (β = - 0.71, P <  0.01), glycosylated hemoglobin (HbA1c) (β = - 0.44, P <  0.01) and homeostatic model assessment of β-cell function (HOMA-β) (β = 9.02, P <  0.01).

CONCLUSIONS

Sitagliptin treatment could significantly increase serum adropin levels in participants with newly diagnosed T2D. The increase in serum adropin levels could be associated with the amelioration of glucose metabolism, which might be involved in beneficial glucose-lowering mechanisms of sitagliptin.

TRIAL REGISTRATION

Clinicaltrials.gov , NCT04495881 . Retrospectively registered on 03/08/2020.

LncRNA HDAC11-AS1 Suppresses Atherosclerosis by Inhibiting HDAC11-Mediated Adropin Histone Deacetylation

LncRNA HDAC11-AS1 (HDAC11-AS1) is the natural antisense transcript of HDAC11, a key enzyme for DNA histone deacetylation. We evaluated the role of HDAC11-AS1 in atherosclerosis. In this research, we found that HDAC11-AS1 ameliorated blood lipid levels and atherosclerosis in high fat-dieted apoE-/- mice by regulating HDAC11 negatively. The change in blood lipid levels is related to the expression of LPL, which is enhanced by HDAC11-AS1 through regulating adropin histone deacetylation in vitro and in vivo. In conclusion, HDAC11-AS1 plays an anti-atherogenic role through adropin to induce LPL expressions, thereby enhancing TG metabolism. The results are valuable for the further development of HDAC11-AS1 and its clinical applications. It provides a new clinical therapeutic target for cardiovascular disease treatment.

Role of adropin in arterial stiffening associated with obesity and type 2 diabetes

Adropin is a peptide largely secreted by the liver and known to regulate energy homeostasis; however, it also exerts cardiovascular effects. Herein, we tested the hypothesis that low circulating levels of adropin in obesity and type 2 diabetes (T2D) contribute to arterial stiffening. In support of this hypothesis, we report that obesity and T2D are associated with reduced levels of adropin (in liver and plasma) and increased arterial stiffness in mice and humans. Establishing causation, we show that mesenteric arteries from adropin knockout mice are also stiffer, relative to arteries from wild-type counterparts, thus recapitulating the stiffening phenotype observed in T2D db/db mice. Given the above, we performed a set of follow-up experiments, in which we found that 1) exposure of endothelial cells or isolated mesenteric arteries from db/db mice to adropin reduces filamentous actin (F-actin) stress fibers and stiffness, 2) adropin-induced reduction of F-actin and stiffness in endothelial cells and db/db mesenteric arteries is abrogated by inhibition of nitric oxide (NO) synthase, and 3) stimulation of smooth muscle cells or db/db mesenteric arteries with a NO mimetic reduces stiffness. Lastly, we demonstrated that in vivo treatment of db/db mice with adropin for 4 wk reduces stiffness in mesenteric arteries. Collectively, these findings indicate that adropin can regulate arterial stiffness, likely via endothelium-derived NO, and thus support the notion that "hypoadropinemia" should be considered as a putative target for the prevention and treatment of arterial stiffening in obesity and T2D.NEW & NOTEWORTHY Arterial stiffening, a characteristic feature of obesity and type 2 diabetes (T2D), contributes to the development and progression of cardiovascular diseases. Herein we establish that adropin is decreased in obese and T2D models and furthermore provide evidence that reduced adropin may directly contribute to arterial stiffening. Collectively, findings from this work support the notion that "hypoadropinemia" should be considered as a putative target for the prevention and treatment of arterial stiffening in obesity and T2D.

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.

Daily Treatment of Mice with Type 2 Diabetes with Adropin for Four Weeks Improves Glucolipid Profile, Reduces Hepatic Lipid Content and Restores Elevated Hepatic Enzymes in Serum

Adropin is a peptide hormone encoded by Energy Homeostasis Associated gene. Adropin modulates energy homeostasis and metabolism of lipids and carbohydrates. There is growing evidence demonstrating that adropin enhances insulin sensitivity and lowers hyperlipidemia in obese mice. The aim of this study was to investigate the effects of daily administration of adropin for four weeks in mice with experimentally induced type 2 diabetes (T2D). Adropin improved glucose control without modulating insulin sensitivity. Adropin reduced body weight, size of adipocytes, blood levels of triacylglycerol and cholesterol in T2D mice. T2D mice treated with adropin had lower liver mass, reduced hepatic content of triacylglycerol and cholesterol. Furthermore, adropin attenuated elevated blood levels of hepatic enzymes (ALT, AST, GGT and ALP) in T2D mice. In T2D mice, adropin increased the circulating adiponectin level. Adropin had no effects on circulating insulin and glucagon levels and did not alter pancreatic islets morphology. These results suggest that adropin improves glucose control, lipid metabolism and liver functions in T2D. In conjunction with reduced lipid content in hepatocytes, these results render adropin as an interesting candidate in therapy of T2D.

Adropin’s Role in Energy Homeostasis and Metabolic Disorders

Adropin is a novel 76-amino acid-peptide that is expressed in different tissues and cells including the liver, pancreas, heart and vascular tissues, kidney, milk, serum, plasma and many parts of the brain. Adropin, encoded by the Enho gene, plays a crucial role in energy homeostasis. The literature review indicates that adropin alleviates the degree of insulin resistance by reducing endogenous hepatic glucose production. Adropin improves glucose metabolism by enhancing glucose utilization in mice, including the sensitization of insulin signaling pathways such as Akt phosphorylation and the activation of the glucose transporter 4 receptor. Several studies have also demonstrated that adropin improves cardiac function, cardiac efficiency and coronary blood flow in mice. Adropin can also reduce the levels of serum triglycerides, total cholesterol and low-density lipoprotein cholesterol. In contrast, it increases the level of high-density lipoprotein cholesterol, often referred to as the beneficial cholesterol. Adropin inhibits inflammation by reducing the tissue level of pro-inflammatory cytokines such as tumor necrosis factor alpha and interleukin-6. The protective effect of adropin on the vascular endothelium is through an increase in the expression of endothelial nitric oxide synthase. This article provides an overview of the existing literature about the role of adropin in different pathological conditions.

Adropin Improves Radiation-Induced Myocardial Injury via VEGFR2/PI3K/Akt Pathway

Mediastinal cancer radiotherapy exposes the heart and causes myocardial injury. It is of utmost importance to identify effective prevention and treatment targets. In this study, the regulatory role of adropin (Ad) in radiation-induced myocardial injury (RIMI) was explored in mice. After C57BL/6 mice were administered E0771 cells and received radiotherapy, the effects of exogenous Ad intervention on myocardial fibrosis, apoptosis, microvessel density, oxidative stress, and protein expression levels were observed. The results showed that exogenous Ad effectively improved cardiac function, suppressed oxidative stress, inhibited myocardial fibrosis, reduced myocardial apoptosis, and promoted microangiogenesis in RIMI mice. Ad also downregulated the expression levels of transforming growth factor β1 (TGF-β1), NADPH oxidase 4 (NOX4), and cleaved caspase 3 and upregulated the expression of phosphor-endothelial nitric oxide synthase (p-eNOS). However, the above-mentioned effects of Ad were significantly reversed in Ad^−/− mice. Radiotherapy resulted in the downregulation of phosphor-vascular endothelial growth factor receptor (p-VEGFR2) and p-Akt in myocardial tissue, which were upregulated by Ad. However, after targeted inhibition of VEGFR2 with apatinib, the effect of Ad on improving RIMI was significantly reversed. Taken together, exogenous Ad significantly ameliorated RIMI by reducing oxidative stress, promoting microangiogenesis, and inhibiting myocardial fibrosis and apoptosis. The underlying molecular mechanism involved may be elucidated by activation of the VEGFR2/PI3K/Akt pathway.

Short-term circuit resistance training improves insulin resistance probably via increasing circulating Adropin

Aim and background

The underlying mechanism of exercise-induced insulin resistance (IR) improvement is unclear. Adropin is a multifunctional peptide has a significant role in the regulation of physical activity and insulin sensitivity. Thus, the aim of this study was to evaluate the effects of various circuit resistance (CRT) intensities on circulating adropin levels and IR and their relation.

Method

Forty-five voluntarily male men randomly were divided into 5 groups; control and 4 groups of CRT (20%, 40%, 60% and 80% of one-repetition maximum (1-RM)). Training groups performed CRT protocol 3 times a week for 6 weeks. Blood samples were drawn before and 48 h after the last training session and used for analyzing serum levels of adropin, glucose and insulin.

Results

The results showed that varying CRT intensities were associated with adropin elevation in comparison to the control group. Further analysis revealed that plasma adropin is higher in the 20% 1-RM group compared to the 40% 1-RM group. Furthermore, fasting insulin and glucose, as well as IR, were decreased in response to different CRT intensities. In addition, these reductions were significantly correlated with adropin level.

Conclusion

It can be speculated that different CRT intensities improve IR probably via increasing adropin level, and should be considered as an effective training method for diminishing glucose metabolism disorders.

Towards harnessing the value of organokine crosstalk to predict the risk for cardiovascular disease in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Importantly, NAFLD increases the risk for cardiovascular disease (CVD). A causal relationship has been substantiated. Given the pandemic proportions of NAFLD, a reliable scoring system for predicting the risk of NAFLD-associated CVD is an urgent medical need. We here review cumulative evidence suggesting that systemically released organokines - especially certain adipokines, hepatokines, and cardiokines - may serve this purpose. The underlying rationale is that these signalers directly communicate between white adipose tissue, liver, and heart as key players in the pathogenesis of NAFLD and resultant CVD events. Moreover, evidence suggests that these organ-specific cytokines are secreted in a biologically predetermined, cascade-like pattern. Consequently, upon pinpointing organokines of relevance, we sketch requirements to establish an algorithm predictive of the CVD risk in patients with NAFLD. Such an algorithm, as to be consolidated in the form of an applicable equation, may be improved continuously by machine learning. To the best of our knowledge, such an option has not yet been considered. Establishing and implementing a reliable algorithm for determining the NAFLD-associated CVD risk has the potential to save many NAFLD patients from life-threatening CVD events.

Role of rs7903146 polymorphism and adropin serum level in patients with diabetes mellitus; a case-control study from Isfahan, Iran

BACKGROUND

Type-2 diabetes mellitus (T2DM) is the common endocrinopathy which characterised by insulin resistance, insufficient expression or secretion of insulin and decrement of insulin effectiveness. Although T2DM has unknown aetiology, the strongest susceptible gene in this disease is TCF7L2. Adropin peptide may have roles in T2DM pathogenesis due to several roles in glucose tolerance, decrement of insulin resistance, lipid metabolism and energy homoeostasis.

AIM

To evaluate the serum level of adropin in T2DM patients and comparing with healthy individuals as well as assessing frequency of rs7903146 genotypes/alleles in patients and control groups.

METHODS

We analysed the frequency of rs7903146 genotypes/alleles in 93 patients with T2DM disease and 53 healthy individuals by the method of polymerase chain reaction-restriction fragment length polymorphism analysis. The serum level of adropin was measured by using enzyme-linked immunosorbent assay technique.

RESULTS

The mean serum level of adropin was 12.32 ± 2.98 and 9.51 ± 2.73 in patients and control groups, respectively (p value < .001). Also, there were significant difference in frequency of genotypes and alleles of rs7903146 in patients and controls groups (p < .001). The rs7903146T/T and rs7903146C/T genotypes increased risk of T2DM disease (OR: 6.035 and OR: 3.082, respectively). Interestingly, the highest level of adropin was detected in T2DMpatients with rs7903146T/T genotype.

CONCLUSION

Our analysis showed higher level of adropin in T2DM patients and increased risk of T2DM with rs7903146T/T and rs7903146C/T genotypes.

Circulating levels of adropin and overweight/obesity: a systematic review and meta-analysis of observational studies

The association between circulating adropin levels and overweight/obesity is currently unclear. The aim of this study was thus to investigate and seek to determine the association between circulating adropin levels and overweight/obesity using the meta-analysis approach of observational studies. A comprehensive literature search was carried out through the PubMed, Web of Science, and SCOPUS databases to identify relevant observational studies that assessed the relationship between circulating adropin levels and overweight/obesity up to September 2020. A random-effects model was used to compute the pooled weighted mean difference (WMD) with 95% confidence intervals (CI). The meta-analysis of five studies (n = 643 participants) showed that circulating adropin levels were significantly lower in the overweight/obese vs. the normal-weight participants (WMD =  - 0.96 ng/ml, 95% CI =  - 1.72 to - 0.19, P = 0.01; I² = 88.4%). In subgroup analyses, lower circulating adropin levels in obese participants compared with normal-weight were observed in Asians (WMD =  - 1.58 ng/ml, 95% CI =  - 1.96 to - 1.21, P < 0.001; I² = 0.00%), and in patients with metabolic disorders (WMD =  - 1.26 ng/ml, 95% CI =  - 1.76 to - 0.77, P < 0.001; I² = 44.6%), respectively. Circulating adropin levels were significantly lower in overweight/obese vs. normal-weight participants, suggesting a possible role of this hormone in the development of obesity. However, the present research indicates that further studies are needed to conclusively confirm whether adropin is a viable marker of obesity.

Hepatic Adropin is Regulated by Estrogen and Contributes to Adverse Metabolic Phenotypes in Ovariectomized Mice

Objective

Menopause is associated with visceral adiposity, hepatic steatosis and increased risk for cardiovascular disease. As estrogen replacement therapy is not suitable for all postmenopausal women, a need for alternative therapeutics and biomarkers has emerged.

Methods

9-week-old C57BL/6 J female mice were subjected to ovariectomy (OVX) or SHAM surgery (n = 10 per group), fed a standard diet and sacrificed 6- & 12 weeks post-surgery.

Results

Increased weight gain, hepatic triglyceride content and changes in hepatic gene expression of Cyp17a1, Rgs16, Fitm1 as well as Il18, Rares2, Retn, Rbp4 in mesenteric visceral adipose tissue (VAT) were observed in OVX vs. SHAM. Liver RNA-sequencing 6-weeks post-surgery revealed changes in genes and microRNAs involved in fat metabolism in OVX vs. SHAM mice. Energy Homeostasis Associated gene (Enho) coding for the hepatokine adropin was significantly reduced in OVX mice livers and strongly inversely correlated with weight gain (r = −0.7 p < 0.001) and liver triglyceride content (r = −0.4, p = 0.04), with a similar trend for serum adropin. In vitro, Enho expression was tripled by 17β-estradiol in BNL 1 ME liver cells with increased adropin in supernatant. Analysis of open-access datasets revealed increased hepatic Enho expression in estrogen treated OVX mice and estrogen dependent ERα binding to Enho. Treatment of 5-month-old OVX mice with Adropin (i.p. 450 nmol/kg/twice daily, n = 4,5 per group) for 6-weeks reversed adverse adipokine gene expression signature in VAT, with a trended increase in lean body mass and decreased liver TG content with upregulation of Rgs16.

Conclusions

OVX is sufficient to induce deranged metabolism in adult female mice. Hepatic adropin is regulated by estrogen, negatively correlated with adverse OVX-induced metabolic phenotypes, which were partially reversed with adropin treatment. Adropin should be further explored as a potential therapeutic target and biomarker for menopause-related metabolic derangement.

•

OVX increased body weight, liver fat & adverse visceral fat adipokine signature.

•

OVX altered liver transcriptome & miRNA profile including fat metabolism pathways.

•

Enho was downregulated by OVX & inversely correlated with weight gain & liver fat.

•

Hepatic adropin expression was upregulated by estrogen in-vitro & in-vivo.

•

Adropin treatment partially reversed OVX induced adverse metabolic phenotypes.

The association between serum adropin and carotid atherosclerosis in patients with type 2 diabetes mellitus: a cross‑sectional study

BACKGROUND

Adropin, a newly‑identified energy homeostasis protein, has been implicated in the maintenance of metabolic homeostasis and insulin sensitivity. This study attempts to measure the association between serum adropin and carotid atherosclerosis in patients with type 2 diabetes mellitus (T2DM).

METHODS

This cross‑sectional study was performed in 503 hospitalized patients with T2DM.Serum adropin level was measured by a sandwich enzyme-linked immunosorbent assay. The carotid atherosclerosis was assessed by color Doppler sonography. The association between adropin and carotid atherosclerotic plaque was tested by logistic regression model. The effect of adropin on carotid intimal-medial thickness (CIMT) was estimated using linear regression model.

RESULTS

Overall, 280 (55.7%) patients had carotid atherosclerotic plaque. The risk of carotid atherosclerotic plaque decreased with the increment of serum adropin level (adjusted odds ratio [aOR], 0.90; 95%CI: 0.81-0.99) in patients with T2DM. Serum adropin (Standardized β = - 0.006, p = 0.028) was also independently protective factor for CIMT in patients with T2DM.

CONCLUSION

In patients with T2DM, high serum adropin level was correlated with a decreased risk of carotid atherosclerosis in T2DM patients. Low circulating level of adropin may promote carotid atherosclerosis.

Maternal adropin levels in patients with gestational diabetes mellitus: a systematic review and meta-analysis

BACKGROUND

Adropin is a regulatory protein with potential implications in energy homeostasis, glucose regulation, and insulin resistance.

AIM

The aim of this meta-analysis was to compare the maternal serum/plasma adropin levels between gestational diabetes mellitus (GDM) patients and non-GDM controls.

METHODS

Relevant studies were retrieved by online database and manual searching. The standardized mean differences (SMDs) with 95% confidence intervals (CIs) were obtained by a random-effects meta-analysis. A one-study leave-out sensitivity analysis and trimester-wise subgroup analysis were performed.

RESULTS

A total of eight observations were included in this meta-analysis. The results based on random-effects meta-analysis indicated that adropin levels were significantly increased in GDM patients as compared to non-GDM controls (SMD = 2.41, 95% CI = 0.52-4.29, p= .01). The sensitivity analysis indicated that no single study had significantly influenced the overall outcome.

CONCLUSIONS

The results indicate that maternal serum/plasma adropin concentrations were significantly higher in GDM patients as compared to non-GDM controls suggesting the potential associations of adropin in GDM. Despite this, further studies are needed to investigate the mechanistic, diagnostic and prognostic roles of trimester-wise adropin levels in GDM and associated fetal outcomes.

Neurovascular protection by adropin in experimental ischemic stroke through an endothelial nitric oxide synthase-dependent mechanism

Adropin is a highly-conserved peptide that has been shown to preserve endothelial barrier function. Blood-brain barrier (BBB) disruption is a key pathological event in cerebral ischemia. However, the effects of adropin on ischemic stroke outcomes remain unexplored. Hypothesizing that adropin exerts neuroprotective effects by maintaining BBB integrity, we investigated the role of adropin in stroke pathology utilizing loss- and gain-of-function genetic approaches combined with pharmacological treatment with synthetic adropin peptide. Long-term anatomical and functional outcomes were evaluated using histology, MRI, and a battery of sensorimotor and cognitive tests in mice subjected to ischemic stroke. Brain ischemia decreased endogenous adropin levels in the brain and plasma. Adropin treatment or transgenic adropin overexpression robustly reduced brain injury and improved long-term sensorimotor and cognitive function in young and aged mice subjected to ischemic stroke. In contrast, genetic deletion of adropin exacerbated ischemic brain injury, irrespective of sex. Mechanistically, adropin treatment reduced BBB damage, degradation of tight junction proteins, matrix metalloproteinase-9 activity, oxidative stress, and infiltration of neutrophils into the ischemic brain. Adropin significantly increased phosphorylation of endothelial nitric oxide synthase (eNOS), Akt, and ERK1/2. While adropin therapy was remarkably protective in wild-type mice, it failed to reduce brain injury in eNOS-deficient animals, suggesting that eNOS is required for the protective effects of adropin in stroke. These data provide the first causal evidence that adropin exerts neurovascular protection in stroke through an eNOS-dependent mechanism. We identify adropin as a novel neuroprotective peptide with the potential to improve stroke outcomes.

Hepatokine Pregnancy Zone Protein Governs the Diet-Induced Thermogenesis Through Activating Brown Adipose Tissue

Intermittent fasting (IF), as a dietary intervention for weight loss, takes effects primarily through increasing energy expenditure. However, whether inter-organ systems play a key role in IF remains unclear. Here, a novel hepatokine, pregnancy zone protein (PZP) is identified, which has significant induction during the refeeding stage of IF. Further, loss of function studies and protein therapeutic experiment in mice revealed that PZP promotes diet-induced thermogenesis through activating brown adipose tissue (BAT). Mechanistically, circulating PZP can bind to cell surface glucose-regulated protein of 78 kDa (GRP78) to promote uncoupling protein 1 (UCP1) expression via a p38 MAPK-ATF2 signaling pathway in BAT. These studies illuminate a systemic regulation in which the IF promotes BAT thermogenesis through the endocrinal system and provide a novel potential target for treating obesity and related disorders.

Call for Emergency Action to Limit Global Temperature Increases, Restore Biodiversity, and Protect Health

Objective

It is known that impaired energy metabolism contributes to the neuropathology of bipolar disorder (BD). This study aimed to compare the levels of glucagon-like peptide-1 (GLP-1), adropin, and desnutrin, which have many metabolic functions besides the regulation of energy metabolism, between patients with BD and healthy controls and to investigate the related factors.

Methods

In the study group, 73 age- and sex-matched participants were included. Of them, 35 were patients diagnosed with BD and 38 were healthy individuals. In the blood samples, in addition to routine biochemistry lipid parameters, the levels of adropin, desnutrin, and GLP-1 were determined.

Results

Adropin, desnutrin, and GLP-1 levels were significantly lower in patients with BD than in healthy controls (P < 0.001). In contrast, body mass index, total cholesterol, triglyceride, and low-density lipoprotein levels were significantly higher in patients with BD than in healthy controls (respectively P < 0.001, P = 0.001, P = 0.002, P = 0.001). It was observed that adropin levels decreased significantly as the duration of the disease increased.

Conclusion

The low levels of adropin, desnutrin, and GLP-1 that we determined in patients with BD indicate that these peptides may be important in BD pathophysiology.

Adropin and insulin resistance: Integration of endocrine, circadian, and stress signals regulating glucose metabolism

Dysregulation of hepatic glucose production (HGP) and glucose disposal leads to hyperglycemia and type 2 diabetes. Hyperglycemia results from the declining ability of insulin to reduce HGP and increase glucose disposal, as well as inadequate ß-cell compensation for insulin resistance. Hyperglucagonemia resulting from reduced suppression of glucagon secretion by insulin contributes to hyperglycemia by stimulating HGP. The actions of pancreatic hormones are normally complemented by peptides secreted by cells distributed throughout the body. This regulatory network has provided new therapeutics for obesity and type 2 diabetes (e.g., glucagon-like peptide 1). Other peptide hormones under investigation show promise in preclinical studies. Recent experiments using mice and nonhuman primates indicate the small secreted peptide hormone adropin regulates glucose metabolism. Here, recent expression profiling data indicating hepatic adropin expression increases with oxidative stress and declines with fasting or in the presence of hepatic insulin resistance and how adropin interacts with the pancreatic hormones, insulin, and glucagon to modulate glycemic control are discussed.

The Intestinal Dysbiosis of Mothers with Gestational Diabetes Mellitus (GDM) and Its Impact on the Gut Microbiota of Their Newborns

Gestational diabetes mellitus (GDM) is defined as “diagnosed as impaired glucose tolerance for the first time during pregnancy,” which can lead to adverse pregnancy outcomes and produces divergent effects on mothers and newborns. In recent years, with the continuous expansion of obese people, GDM shows an upward trend. The abundant and diverse members of the human gut microbiota exert critical roles in the maintenance of human health. Studies have shown that GDM may be associated with disordered gut microbiota in both mothers and newborns. Taking into account the potential effects on maternal and consequently neonatal health, in this review, we analyzed the available data and discussed the current knowledge about the potential relationship between GDM and intestinal dysbiosis in mothers and newborns. In addition, we also discussed the influencing factors derived from GDM mothers on the gut microbiome of their newborns, including the vertical transmission of microbiota from mothers, the alteration of milk components of GDM mothers, and using of probiotics. Hoping that new insights into the role of the gut microbiota in GDM could lead to the development of integrated strategies to prevent and treat these metabolic disorders.

Adropin levels and its associations as a fat-burning hormone in patients with polycystic ovary syndrome: a correlational meta-analysis

AIMS

Adropin is a peptide hormone with potential implications in patients with polycystic ovary syndrome (PCOS). The aim of this meta-analysis was to compare the circulating (serum/plasma) and follicular fluid adropin levels between human PCOS patients and non-PCOS controls.

METHODS

Relevant studies were retrieved by online database and manual searching. The standardized mean differences (SMDs) with 95% confidence intervals (CIs) were obtained by a random-effects meta-analysis. Meta-analysis of correlations was performed for the associations of adropin with anthropometric, lipid, insulin resistance and hormonal covariates. The funnel plot analysis with Begg's and Egger's tests was used for publication bias.

RESULTS

A total of 9 studies were included in this meta-analysis. The results indicated that the adropin levels were significantly decreased in PCOS patients as compared to non-PCOS controls (SMD = -1.87, 95% CI = -2.55 to -1.18, p < .0001). This decrease was more evident in overweight PCOS patients than their normoweight counterparts (SMD = -0.55, 95% CI = -0.80 to -0.30, p < .0001). A one-study leave-out sensitivity analysis indicated that no single study had a significant influence on the overall outcome, suggesting the robustness of this meta-analysis. There were significant associations of decreased adropin levels with the body mass index, dyslipidemia and insulin resistance in PCOS.

CONCLUSION

Adropin levels are significantly reduced in PCOS patients compared to controls, and this decrease was more evident in overweight PCOS patients.

Changes in plasma C1q, apelin and adropin concentrations in older adults after descending and ascending stair walking intervention

This study compared changes in plasma complement component 1q (C1q), apelin and adropin concentrations in older obese women after descending (DSW) and ascending stair walking (ASW) training (n = 15/group) performed twice a week for 12 weeks, with gradual increases in exercise time from 5 to 60 min. Fasting blood samples were collected 3 days before the first and 4 days after the last training session. The improvements in the maximal voluntary isometric contraction (MVIC) strength of the knee extensors, functional physical fitness [e.g., 30-s chair stand (CS) performance], resting systolic blood pressure (SBP), insulin sensitivity [e.g., oral glucose tolerance test (OGTT)] and blood lipid profiles [e.g., total cholesterol (TC)] were greater (p < 0.05) in the DSW than ASW group. Plasma C1q decreased (− 51 ± 30%), and apelin (23 ± 15%) and adropin (127 ± 106%) increased (p ≤ .0.05) only after DSW. Significant (p ≤  0.01) partial correlations were found between the pre- to post-DSW changes in C1q, apelin or adropin and changes in outcome measures [e.g., C1q and MVIC (r = − 0.837), apelin and SBP (r = − 0.854), and andropin and OGTT (r = − 0.729)]. These results showed that greater decreases in plasma C1q and greater increases in apelin and adropin concentrations were associated with greater improvements in outcome measures after DSW than after ASW.

Adropin and spexin hormones regulate the systemic inflammation in adenine-induced chronic kidney failure in rat

Chronic kidney disease is one of the major global health problems. Chronic renal failure is stimulated by many cytokines and chemokines. Adropin and spexin (SPX) are peptides hormones. These peptides could affect inflammatory conditions, but this is unclear. Due to the limited information, we planned to investigate the impact of adropin and SPX hormones on systemic inflammation in adenine induced chronic kidney failure rat model. Chronic kidney failure was induced by administering adenine hemisulfate. Renal functions were measured by an autoanalyzer. Granulocyte colony-stimulating factor (G-CSF), interferon-gamma (IFN-γ), interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, IL-17A, tumor necrosis factor-alpha, Eotaxin, growth-regulated oncogene-alpha, IP-10, monocyte chemoattractant protein (MCP)-1, MCP-3, macrophage inflammatory protein (MIP)-1α, MIP-2, and RANTES levels were determined by Luminex. We observed an increase in 24-h urine volume and serum creatinine. Blood urea nitrogen (BUN) and urine protein levels were also significantly higher in the chronic kidney failure (CKF) group. Urine protein and 24-h urine volume were reduced with adropin and SPX treatments. Furthermore, G-CSF, IFN-γ, IL-4, IL-5, IL-10, IL-12, IL-17A, and GRO-α significantly increased by CKF induction; however, these cytokines and chemokines significantly decreased by adropin treatment in the CKF group. Furthermore, adropin increased IP-10, MCP-1, MIP-1α, and MIP-2 levels. In addition, SPX treatment had a more limited effect, decreasing only G-CSF, IFN-γ, and IL-5 levels. The combined adropin + SPX treatment significantly reduced G-CSF, IFN-γ, IL-4, IL-5, IL-12, and IL-17A. Furthermore, IP-10, MCP-1, MCP-3, and MIP-2 were significantly increased by these combined treatments. Our findings indicate that renal functions and inflammatory response were modulated by adropin and SPX peptides. These peptides may have protective effects on systemic inflammation and renal failure progression.

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.

Adropin correlates with aging-related neuropathology in humans and improves cognitive function in aging mice

The neural functions of adropin, a secreted peptide highly expressed in the brain, have not been investigated. In humans, adropin is highly expressed in astrocytes and peaks during critical postnatal periods of brain development. Gene enrichment analysis of transcripts correlating with adropin expression suggests processes relevant to aging-related neurodegenerative diseases that vary with age and dementia state, possibly indicating survivor bias. In people aged <40 y and 'old-old' (>75 y) diagnosed with dementia, adropin correlates positively with genes involved in mitochondrial processes. In the 'old-old' without dementia adropin expression correlates positively with morphogenesis and synapse function. Potent neurotrophic responses in primary cultured neurons are consistent with adropin supporting the development and function of neural networks. Adropin expression in the 'old-old' also correlates positively with protein markers of tau-related neuropathologies and inflammation, particularly in those without dementia. How variation in brain adropin expression affects neurological aging was investigated using old (18-month) C57BL/6J mice. In mice adropin is expressed in neurons, oligodendrocyte progenitor cells, oligodendrocytes, and microglia and shows correlative relationships with groups of genes involved in neurodegeneration and cellular metabolism. Increasing adropin expression using transgenesis improved spatial learning and memory, novel object recognition, resilience to exposure to new environments, and reduced mRNA markers of inflammation in old mice. Treatment with synthetic adropin peptide also reversed age-related declines in cognitive functions and affected expression of genes involved in morphogenesis and cellular metabolism. Collectively, these results establish a link between adropin expression and neural energy metabolism and indicate a potential therapy against neurological aging.

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.

Molecular cloning and characterization of the novel adropin from tilapia (Oreochromis niloticus): Involvement in the control of food intake

Adropin has been shown to be involved in the regulation of food intake in mice. However, the mechanism of adropin in feeding regulation is still largely unknown. Using the tilapia, Oreochromis niloticus, we identified and characterized a novel form of adropin (designated adropin-b) encoding a 68-amino acid precursor. Although adropin-b shared low amino acid identities with its tilapia paralog (designated adropin-a), synteny analysis proved that tilapia adropin is orthologous to its human counterpart. The transcripts of adropin-b were ubiquitously expressed in various tissues with the highest levels in the olfactory bulb. A decrease in adropin-b mRNA levels was observed 1 h following a meal in the olfactory bulb, hypothalamus, and optic tectum, whereas fasting for 7 days induced an increase in adropin-b mRNA levels in the olfactory bulb, hypothalamus, and optic tectum of tilapia brain. However, no changes in adropin-a mRNA levels were observed in the postprandial and fasting state. Intraperitoneal injection of tilapia adropin-b was shown to increase food consumption, but adropin-a did not affect feeding. Co-treatment of the fish with adropin-b and neuropeptide Y (NPY) had no additive effects on appetite. The appetite stimulatory effects of adropin-b appeared to be mediated by upregulating the orexigenic Npy, Orexin, and Proapelin gene expression, paralleled by inhibition of the mRNA levels of anorexigenic proopiomelanocortin (Pomc) and cocaine-amphetamine-regulated transcript (Cart) in vivo and in vitro. These observations suggested that adropin-b participated in appetite control and gene regulation of central orexigenic and anorexigenic factors in a fish model.

Two weeks of moderate intensity locomotor training increased corticosterone concentrations but did not alter the number of adropin-immunoreactive cells in the hippocampus of diabetic type 2 and control rats

Adropin (ADR) plays a role in metabolism regulation and its alterations in obesity and diabetes have been found. Treatment with ADR was beneficial in metabolic diseases, and physical exercise increased ADR concentrations in obese patients. However, data on the distribution of ADR in the brain are sparse. The role of metabolic status and physical exercise on its expression in the brain is undiscovered. We hypothesized that diabetes type 2 (DM2) and/or exercise will alter number of ADR-immunoractive (-ir) cells in the rat brain. Animals were divided into groups: diabetes type 2 (receiving high-fat diet and injections of streptozotocin) and control (fed laboratory chow diet; C). Rats were further divided into: running group (2 weeks of forced exercise on a treadmill) and non-running group. Body mass, metabolic and hormonal profiles were assessed. Immunohistochemistry was run to study ADR-ir cells in the brain. We found that: 1) in DM2 animals, running decreased insulin and increased glucose concentrations; 2) in C rats, running decreased insulin concentrations and had no effect on glucose concentration in blood; 3) running increased corticosterone (CORT) concentrations in DM2 and C rats; 4) ADR-ir cells were detected in the hippocampus and ADR-ir fibers in the arcuate nucleus of the hypothalamus, which is a novel location; 5) metabolic status and running, however, did not change number of these cells. We concluded that 2 weeks of forced moderate intensity locomotor training induced stress response present as increased concentration of CORT and did not influence number of ADR-ir cells in the brain.