Asprosin attenuates insulin signaling pathway through PKCδ‐activated ER stress and inflammation in skeletal muscle

Novel adipokine asprosin modulates browning and adipogenesis in white adipose tissue

Obesity is an increasingly serious epidemic worldwide characterized by an increase in the number and size of adipocytes. Adipose tissue maintains the balance between lipid storage and energy utilization. Therefore, adipose metabolism is of great significance for the prevention, treatment and intervention of obesity. Asprosin, a novel adipokine, is a circulating hormone mainly secreted by white adipose tissue. Previous studies have shown that asprosin plays a role in fasting-induced homeostasis, insulin resistance, and glucose tolerance. However, whether it can regulate the metabolism of adipose tissue itself has not been studied. This study intended to examine the roles and potential mechanisms of asprosin in adipose regulation. We first demonstrated that the expression level of asprosin was significantly downregulated in subcutaneous white adipose tissue (scWAT) of high-fat diet (HFD)-fed or cold-stimulated mice. Overexpression of asprosin in scWAT reduced heat production, decreased expression of the browning marker uncoupling protein 1 (UCP1) and other browning-related genes, along with upregulation of adipogenic gene expression. Mechanistically, we found that Nrf2 was activated upon cold exposure, but this activation was suppressed after asprosin overexpression. In primary cultured adipocytes, adenovirusmediated asprosin overexpression inhibited adipose browning and aggravated lipid deposition, while Nrf2 agonist oltipraz could reverse these changes. Our findings suggest that novel adipokine asprosin negatively regulated browning and elevate lipid deposition in adipose tissue via a Nrf2-mediated mechanism. Asprosin may be a promising target for the prevention and treatment of obesity and other metabolic diseases.

Increased serum asprosin is correlated with diabetic nephropathy

OBJECTIVE

The adipokine asprosin, which was recently discovered, facilitates hepatic glucose production. The aim of this study is to see whether serum asprosin concentrations are linked to diabetic nephropathy (DN).

METHODS

We performed this investigation in a group of 212 type 2 diabetes (T2DM) patients. These patients were classified into three subgroups: DN0 group (normal to mildly increased), DN1 group (moderately increased), and DN2 group (severely increased) on the basis of urine albumin-to-creatinine ratio (ACR).

RESULTS

When compared to the controls, T2DM patients had higher serum asprosin levels. The DN2 group had significantly higher serum asprosin than the DN0 and DN1 groups. Furthermore, the DN1 group had higher serum asprosin than the DN0 group. Serum asprosin was linked to a higher risk of T2DM and DN in a logistic regression analysis. Serum asprosin was found to be positively related with disease duration, systolic blood pressure, blood urea nitrogen, creatinine, uric acid, ACR, calcium channel blockers, and angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker therapy, but negatively related with glomerular filtration rate, metformin, and acarbose therapy.

CONCLUSION

Serum asprosin increase with the progression of DN. Serum asprosin is correlated with renal function and ACR.

Old Paradoxes and New Opportunities for Appetite Control in Obesity

Human obesity is accompanied by alterations in the blood concentrations of multiple circulating appetite regulators. Paradoxically, most of the appetite-inhibitory hormones are elevated in nonsyndromic obesity, while most of the appetite stimulatory hormones are reduced, perhaps reflecting vain attempts of regulation by inefficient feedback circuitries. In this context, it is important to understand which appetite regulators exhibit a convergent rather than paradoxical behavior and hence are likely to contribute to the maintenance of the obese state. Pharmacological interventions in obesity should preferentially consist of the supplementation of deficient appetite inhibitors or the neutralization of excessive appetite stimulators. Here, we critically analyze the current literature on appetite-regulatory peptide hormones. We propose a short-list of appetite modulators that may constitute the best candidates for therapeutic interventions.

Asprosin serum levels and glucose homeostasis in children with obesity

PURPOSE

Asprosin is a novel adipokine involved in glucose homeostasis, food intake regulation and energy homeostasis. However, the role of asprosin in glucose homeostasis regulation remains still controversial, especially in pediatrics. Aims of the study were to compare fasting serum asprosin levels between obese children and controls and to investigate the relationships of asprosin with body mass index (BMI) and biochemical markers of insulin resistance, insulin sensitivity, β-cell function and cardio-metabolic risk in obese non-diabetic children.

METHODS

This cross-sectional, case-controlled, study included 43 obese children and 24 lean matched controls consecutively recruited. Children underwent clinical and biochemical assessments, including oral glucose tolerance test. Fasting asprosin serum levels were measured using an enzyme-linked immunosorbentassay (ELISA). Homeostasis model assessment of insulin resistance (HOMA-IR), homeostasis model assessment of β-cell function (HOMA-B), Matsuda-index, Insulinogenic-index, Areas Under the Curves for glucose and insulin were calculated. Successively, asprosin variable was dichotomized according to mean value in order to create two ordered classes of values.

RESULTS

Fasting asprosin concentration was significantly lower in obese children compared to controls (331.9 ± 120.5 vs 358.1 ± 74.1 pg/ml; p = 0.013). Asprosin was lower in boys than in girls (313.7 ± 59.5 vs 361.1 ± 127.2 pg/ml; p = 0.044), while BMI standard deviation score (SDS) was higher in boys compared to girls (p = 0.024). Asprosin was negatively correlated with BMI (p = 0.024), BMI SDS (p = 0.044) and male sex (p = 0.043) in the entire cohort. No significant differences in asprosin levels were demonstrated between insulin resistant and non-insulin resistant obese children. Logistic regression models documented a significant negative association between BMI SDS and dichotomized asprosin. In particular, higher BMI SDS values were associated to lower asprosin serum levels class. A receiver operating characteristic (ROC) analysis showed existence of the best cut-off for BMI SDS (+2.7 SDS) variable into discriminating patients belonging to two asprosin classes in our cohort.

CONCLUSIONS

In conclusion, asprosin serum levels were significantly lower in obese children compared to control. Fasting asprosin decreased with increasing BMI, but it was not significantly affected by IR.

Asprosin-A Fasting-Induced, Glucogenic, and Orexigenic Adipokine as a New Promising Player. Will It Be a New Factor in the Treatment of Obesity, Diabetes, or Infertility? A Review of the Literature

Asprosin is a recently discovered protein released during fasting conditions mainly by adipocytes from white adipose tissue. As a glucogenic peptide, it stimulates the release of glucose from hepatic cells by binding to the OLFR734 receptor and leading to the activation of the G protein-cAMP-PKA pathway. As it crosses the blood–brain barrier, it also acts as an orexigenic peptide that stimulates food intake through activation of AgRP neurons in the hypothalamus; thus, asprosin participates in maintaining the body’s energy homeostasis. Moreover, studies have shown that asprosin levels are pathologically elevated in obesity and related diseases. However, the administration of anti-asprosin antibodies can both normalize its concentration and reduce food intake in obese mice, which makes it an interesting factor to combat obesity and related diseases. Current research also draws attention to the relationship between asprosin and fertility, especially in men. Asprosin improves age- and obesity-related decrease in fertility potential by improving sperm motility. It should also be mentioned that plasma asprosin levels can be differentially modulated by physical activity; intense anaerobic exercise increases asprosin level, while aerobic exercise decreases it. However, further research is necessary to confirm the exact mechanisms of asprosin activity and its potential as a therapeutic target.

Association of serum asprosin concentrations with obstructive sleep apnea syndrome

OBJECTIVE

Asprosin, a recently discovered adipokine, stimulates the release of hepatic glucose. The purpose of the current research was to determine the relation between serum asprosin and obstructive sleep apnea syndrome (OSAS).

METHODS

The current investigation enrolled 152 patients with OSAS and 97 control subjects. Serum asprosin concentrations were measured and analyzed.

RESULTS

Higher serum asprosin concentrations were found in patients with OSAS than in the controls. Logistic regression analysis demonstrated that serum asprosin concentrations were associated with an increased risk of OSAS. Patients with severe OSAS had significantly increased asprosin compared to mild and moderate groups. The group with moderate OSAS showed higher serum asprosin levels than the group with mild OSAS. Pearson correlation analysis demonstrated a positive relation between serum asprosin and disease severity. Simple linear regression analyses showed a significant correlation between serum asprosin with body mass index (BMI), fasting plasma glucose (FPG), homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides (TG), and apnea-hypopnea index (AHI), and negatively correlated with high-density lipoprotein cholesterol (HDL-C). Multiple linear regression analysis revealed a significant correlation between serum asprosin with BMI, FPG, HOMA-IR, TG, AHI, and HDL-C.

CONCLUSION

There is a significant correlation between serum asprosin with the presence and severity of OSAS.

High Serum Asprosin Levels Are Associated with Presence of Metabolic Syndrome

OBJECTIVE

Asprosin, a new adipocytokine, has reportedly been associated with glucose release, dyslipidemia, and insulin resistance (IR). However, the relationship of asprosin with metabolic syndrome (MetS) remains unknown. This study aimed to investigate serum asprosin levels in MetS as well as their association with various metabolic parameters in humans.

METHODS

A total of 131 consecutive patients with MetS, and 162 age-matched, healthy subjects were recruited for this study. Serum asprosin concentrations were determined using the enzyme-linked immunosorbent assay. Lipid profile, glucose, insulin, and inflammatory markers were also measured.

RESULTS

Serum asprosin levels were higher in subjects with MetS (23.52 [16.70, 32.05] ng/mL) than in controls (16.70 [12.87, 22.38] ng/mL; P < 0.01), and they showed an increasing trend with increasing numbers of metabolic components (P for trend < 0.01). In all studied subjects, serum asprosin levels were positively correlated with body mass index, waist circumference, triglycerides, fasting plasma glucose, 2-hour plasma glucose, fasting insulin, homeostatic model assessment of insulin resistance (HOMA-IR) index, interleukin-6, and monocyte chemoattractant protein-1 and negatively correlated with high-density lipoprotein cholesterol (P < 0.05). In multiple linear regression, asprosin was independently and positively correlated with triglyceride and HOMA-IR (P < 0.05). Binary logistic regression revealed that asprosin was independently and positively correlated with the occurrence of MetS and IR, even after controlling for anthropometric variables, lipid profiles, and inflammatory markers.

CONCLUSION

Asprosin is a potential metabolic-related adipokine and may be related to IR and MetS. This trial was registered with ChiCTR, ChiCTR1800018347.

Expression and purification of asprosin in Pichia pastoris and investigation of its increase glucose uptake activity in skeletal muscle through activation of AMPK

Asprosin is a new hormone released from white adipose tissue (WAT) that not only promotes glucose release in the liver but also activates orexigenic neurons in the hypothalamus to promote appetite and weight gain. Its effect on skeletal muscle glucose uptake is unclear. This research, a stable asprosin expression system was formed by first constructing a eukaryotic expression vector pPIC9K-8His-Asprosin, and then transforming it into the Pichia pastoris strain GS115. Pichia pastoris methanol induction combined with Nickel-NTA magnetic beads purification strategy was used to express and purify asprosin protein. Purified asprosin can promote the phosphorylation of PKA substrate, and intraperitoneal injection of asprosin can increase blood glucose. After proteolysis and detection by mass spectrometry, asprosin was found to have 3 glycosylation sites and multiple glycosyl types. Asprosin up-regulated glucose transporter 4 (GLUT4) expression in myotubes, including mRNA and protein levels. In addition, asprosin enhanced AMP-activated protein kinase (AMPK) phosphorylation, but it had no effect on AKT phosphorylation with or without insulin treatment. Treatment with an AMPK inhibitor (compound C) reduced the asprosin-mediated glucose uptake effect. These results show that purified asprosin activated AMPK signaling in skeletal muscle and further promoted glucose uptake. From the perspective of skeletal muscle uptake of glucose, asprosin may have beneficial effects on type 2 diabetes.

A state of the art review on the novel mediator asprosin in the metabolic syndrome

Metabolic syndrome is a complex and heterogeneous pathology characterized by a cluster of biochemical, clinical, and metabolic factors that came together in raising the risk of cardiovascular diseases, type 2 diabetes mellitus, and all-cause mortality. Some of these features are well defined in this syndrome like: obesity, inflammation, hypertension, insulin resistance, atherosclerotic dyslipidemias, endothelial dysfunction, and inflammation. This circuit is intermediated by a complex network of hormones, cytokines, transcription factors, and adipokines, among others. Some like leptin, adiponectin, Plasminogen activator inhibitor-1, interleukin-6, Tumor necrosis factor, and their influence on the metabolic syndrome are well described in the literature and new players are described continuously. One novel player was described in 2016 by Romere et al as a fasting-induced glycogenic protein hormone named asprosin. In order to perform a state-of-the-art, nonsystematic review of asprosin, a study of the available literature was carried out in the main database (Pubmed) and the results were studied and correlated to better understand the mechanism of action of this hormone. Asprosin is not only associated with the metabolic syndrome features like glucose and lipid metabolism, insulin resistance, obesity and inflammation but also in other pathologies metabolic syndrome related like diabetic retinopathy, polycystic ovary syndrome and anorexia nervosa. A limited number of pathways were already unveiled although much more research is needed to better understand the therapeutical potential of asprosin in the metabolic syndrome.

The Role of Oxymatrine in Amelioration of Acute Lung Injury Subjected to Myocardial I/R by Inhibiting Endoplasmic Reticulum Stress in Diabetic Rats

Background

Oxymatrine (OMT) is the primary pharmacological component of Sophora flavescens Aiton., which has been shown to possess potent antifibrotic, antioxidant, and anti-inflammatory activities. The aim of the present study was to clarify the protective mechanism of OMT on acute lung injury (ALI) subjected to myocardial ischemia/reperfusion (I/R).

Methods

A myocardial I/R-induced ALI model was achieved in diabetic rats by occluding the left anterior descending coronary artery for 1 h, followed by reperfusion for 1 h. The levels of inflammatory factors (tumor necrosis factor-α, interleukin- (IL-) 6, and IL-17) in bronchoalveolar lavage fluid were assessed using commercially available kits. The index of myocardial injury, including the detection of cardiac troponin I (cTnI), cardiac troponin T (cTnT), lactate dehydrogenase (LDH), and creatine kinase-MB (CK-MB), was also determined using commercially available kits. Hematoxylin and eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling were used to identify histological changes. The expression levels of endoplasmic reticulum chaperone BiP (GRP78), DNA damage-inducible transcript 3 protein (CHOP), eukaryotic translation initiation factor 2-alpha kinase 3 (PERK), inositol dependent enzyme 1α (IRE1α), ATF6, caspase-3, -9, and-12, Bcl-2, and Bax were determined by Western blotting. The mRNA expression levels of GRP78 and CHOP were detected by reverse transcription-quantitative PCR.

Results

Myocardial I/R increased the levels of cTnI, cTnT, LDH, and CK-MB in diabetic rats. Damaged and irregularly arranged myocardial cells were also observed, as well as more serious ALI with higher lung injury scores and WET/DRY ratios and lower PaO₂. Moreover, the expression of key proteins of endoplasmic reticulum stress (ERS) was increased by I/R injury, including phosphorylated- (p-) PERK, p-IRE1ɑ, and ATF6, as well as decreased levels of apoptosis. These effects were all significantly reversed by OMT treatment.

Conclusions

OMT protects against ALI subjected to myocardial I/R by inhibiting ERS in diabetic rats.

The role of Asprosin in patients with dilated cardiomyopathy

Background

Asprosin is a novel fasting glucogenic adipokine discovered in 2016. Asprosin induces rapid glucose releases from the liver. However, its molecular mechanisms and function are still unclear. Adaptation of energy substrates from fatty acid to glucose is recently considered a novel therapeutic target in heart failure treatment. We hypothesized that the asprosin is able to modulate cardiac mitochondrial functions and has important prognostic implications in dilated cardiomyopathy (DCM) patients.

Methods

We prospectively enrolled 50 patients (86% male, mean age 55 ± 13 years) with DCM and followed their 5-year major adverse cardiovascular events from 2012 to 2017. Comparing with healthy individuals, DCM patients had higher asprosin levels (191.2 versus 79.7 ng/mL, P < 0.01).

Results

During the 5-year follow-up in the study cohort, 16 (32.0%) patients experienced adverse cardiovascular events. Patients with lower asprosin levels (< 210 ng/mL) were associated with increased risks of adverse clinical outcomes with a hazard ratio of 7.94 (95% CI 1.88–33.50, P = 0.005) when compared patients with higher asprosin levels (≥ 210 ng/mL). Using cardiomyoblasts as a cellular model, we showed that asprosin prevented hypoxia-induced cell death and enhanced mitochondrial respiration and proton leak under hypoxia.

Conclusions

In patients with DCM, elevated plasma asprosin levels are associated with less adverse cardiovascular events in five years. The underlying protective mechanisms of asprosin may be linked to its functions relating to enhanced mitochondrial respiration under hypoxia.

Asprosin promotes β-cell apoptosis by inhibiting the autophagy of β-cell via AMPK-mTOR pathway

Asprosin is a newly discovered adipokine. A recent study showed that asprosin promoted the β-cell apoptosis of MIN6 cells. This study aims to determine whether asprosin induces the apoptosis in β-cell via regulating autophagy. Mouse insulinoma MIN6 cells were divided into the following four groups: control, vehicle, high glucose, and asprosin groups. MIN6 cells in the asprosin group were transfected with recombinant asprosin-T2A-GFP vector. MIN6 cells in the vehicle group were transfected with vector only. Then the apoptosis of MIN6 cells was detected using flow cytometry. Real-time polymerase chain reaction and western blot were used to determine the expression of caspase 3, LC3-I, LC3-II, beclin 1, P62, AMP activated protein kinase (AMPK), and mammalian target of rapamycin (mTOR). AMPK pathway was enhanced using AMPK agonist AICAR. High glucose and asprosin induced the apoptosis of MIN6 cells and elevated expression of caspase 3. In addition, high glucose and asprosin resulted in reduced expression of LC3-II/LC3-I, beclin 1, and increased expression of P62. p-AMPK expression was decreased and p-mTOR expression was increased after high glucose and asprosin treatment. AMPK agonist AICAR was used to activate the AMPK pathway. Treatment with AICAR significantly partly restored decreased autophagy and increased apoptosis of β-cell, which was induced by asprosin. Asprosin promotes the apoptosis of β-cell by inhibiting the autophagy of β-cell via AMPK-mTOR pathway.

Circulating asprosin levels are increased in patients with type 2 diabetes and associated with early-stage diabetic kidney disease

PURPOSE

Asprosin was a newly identified secreted hormone which could induce hepatic glucose release. Since asprosin closely associated with the risk factors of diabetic kidney disease (DKD), including hyperglycemia, insulin resistance and inflammation, the present study aimed to investigate the relationship between circulating asprosin levels and the early stage of DKD.

METHODS

30 subjects with normal glucose tolerance (NGT), 42 type 2 diabetes (T2DM) patients without DKD and 33 T2DM patients with early stage of DKD were recruited. Early stage of DKD was defined as two consecutive measurements of urinary albumin-to-creatinine ratio (UACR) 30-299 mg/g and estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73m². Multiple linear regression analysis was conducted to explore the associations of circulating asprosin levels with eGFR and UACR. Multiple logistic regression analysis was used to determine the association of circulating asprosin levels with the early stage of DKD.

RESULTS

Circulating asprosin levels in Non-DKD and DKD groups were significantly higher than that in NGT group and the DKD group showed the highest levels. Circulating asprosin levels negatively correlated with eGFR (r = - 0.311, P = 0.007) and positively correlated with UACR (r = 0.345, P = 0.002) in T2DM patients. Even after multivariable adjustment, circulating asprosin levels were closely associated with eGFR and UACR and significantly increased ORs for early stage of DKD (OR = 3.973, P = 0.001).

CONCLUSION

Circulating asprosin levels were increased in T2DM and associated with the early stage of DKD. The specific role of asprosin in DKD needs further investigation.

The endoplasmic reticulum stress and related signal pathway mediated the glyphosate-induced testosterone synthesis inhibition in TM3 cells

Glyphosate is the most widely used herbicide in the world. In recent years, many studies have demonstrated that exposure to glyphosate-based herbicides (GHBs) was related to the decrease of serum testosterone and the decline in semen quality. However, the molecular mechanism of glyphosate-induced testosterone synthesis disorders is still unclear. In the present study, the effects of glyphosate on testosterone secretion and the role of endoplasmic reticulum (ER) stress in the process were investigated in TM3 cells. The effects of glyphosate at different concentrations on the viability of TM3 cells were detected by CCK8 method. The effect of glyphosate exposure on testosterone secretion was determined by enzyme-linked immunosorbent assay (ELISA). The expression levels of testosterone synthases and ER stress-related proteins were detected by Western blot and Immunofluorescence stain. Results showed that exposure to glyphosate at concentrations below 200 mg/L had no effect on cell viability, while the glyphosate above 0.5 mg/L could inhibit the testosterone secretion in TM3 cells. Treatment TM3 cells with glyphosate at 5 mg/L not only reduced the protein levels of testosterone synthase StAR and CYP17A1, inhibited testosterone secretion, but also increased the protein level of ER stress molecule Bip and promoted the phosphorylation of PERK and eIF2α. Pretreatment cells with PBA, an inhibitor of ER stress, alleviated glyphosate-induced increase in Bip, p-PERK and p-eIF2α protein levels, meanwhile rescuing glyphosate-induced testosterone synthesis disorders. When pretreatment with GSK2606414, a PERK inhibitor, the glyphosate-induced phosphorylation of PERK and eIF2α was blocked, and the glyphosate-inhibited testosterone synthesis and secretion was also restored. Overall, our findings suggest that glyphosate can interfere with the expression of StAR and CYP17A1 and inhibit testosterone synthesis and secretion via ER stress-mediated the activation of PERK/eIF2α signaling pathway in Leydig cells.

Fibrillin-1 and fibrillin-1-derived asprosin in adipose tissue function and metabolic disorders

The extracellular matrix microenvironment of adipose tissue is of critical importance for the differentiation, remodeling and function of adipocytes. Fibrillin-1 is one of the main components of microfibrils and a key player in this process. Furin processing of profibrillin-1 results in mature fibrillin-1 and releases the C-terminal propeptide as a circulating hunger hormone, asprosin. Mutations in the fibrillin-1 gene lead to adipose tissue dysfunction and causes Marfan syndrome, marfanoid progeroid lipodystrophy syndrome, and neonatal progeroid syndrome. Increased TGF-β signaling, altered mechanical properties and impaired adipogenesis are potential causes of adipose tissue dysfunction, mediated through deficient microfibrils. Circulating asprosin on the other hand is secreted primarily by white adipose tissue under fasting conditions and in obesity. It increases hepatic glucose production and drives insulin secretion and appetite stimulation through inter-organ cross talk. This review discusses the metabolic consequences of fibrillin-1 and fibrillin-1-derived asprosin in pathological conditions. Understanding the dynamic role of fibrillin-1 in the adipose tissue milieu and of circulating asprosin in the body can provide novel mechanistic insights into how fibrillin-1 may contribute to metabolic syndrome. This could lead to new management regimens of patients with metabolic disease.

Higher Serum Asprosin Level is Associated with Urinary Albumin Excretion and Renal Function in Type 2 Diabetes

AIM

We detected whether serum asprosin levels play a role in the occurrence and development of albuminuria in patients with type 2 diabetes mellitus (T2DM), which has not been previously discussed.

METHODS

Based on urinary albumin/creatinine ratio (UACR), 207 T2DM patients were divided into T2DM patients with normoalbuminuria (UACR<30 mg/g), microalbuminuria (30≤UACR<300 mg/g), and macroalbuminuria (UACR≥300 mg/g). Serum asprosin levels were determined by enzyme-linked immunosorbent assay.

RESULTS

Comparatively, the serum asprosin levels in T2DM patient groups with macroalbuminuria [2.37 (1.63-3.57)] and microalbuminuria [2.10 (1.60-2.90)] were significantly increased than the normoalbuminuria group [1.59 (1.18-2.09)] (P<0.001). Importantly, the serum level of asprosin was positively correlated with UACR (r=0.304, P<0.001), creatinine (r=0.157, P=0.024), blood urea nitrogen (BUN) (r=0.244, P<0.001), and negatively with glomerular filtration rate (eGFR) (r=-0.159, P=0.022). Furthermore, multiple stepwise regression analyses showed that asprosin was significantly and independently related to UACR, BUN, DBP, and LDL-C (P<0.05). Besides, after adjustment for the confounders, the serum asprosin level was constantly and independently associated with the development of albuminuria in T2DM patients [OR (95% CI): 2.003 (1.37~2.928), P <0.001].

CONCLUSION

Obviously, the serum asprosin level was independently correlated with UACR in T2DM patients, which implies circulating asprosin may play an essential role in the pathogenesis of diabetic nephropathy.

Serum Levels of Asprosin, a Novel Adipokine, Are Significantly Lowered in Patients with Acromegaly

BACKGROUND

Asprosin is a novel identified adipokine secreted mainly by white adipose tissue, which is elevated in metabolic diseases such as diabetes and obesity. Acromegaly is a syndrome caused by pituitary growth hormone (GH) cell adenoma with excessive GH secretion. Serum adipocytokines levels may be involved in abnormal glycolipid metabolism in acromegaly patients.

OBJECTIVES

To investigate serum asprosin levels in acromegaly patients and its correlation with high GH levels and glucolipid metabolic parameters.

METHODS

A retrospective case-control study was conducted and 68 acromegaly patients and 121 controls were included in this study. Clinical information and laboratory examinations were collected and serum asprosin levels were measured by commercial ELISA kits.

RESULTS

Serum asprosin levels in acromegaly patients were significantly lower than controls (P < 0.001). Serum asprosin levels in patients with the course of acromegaly ≥5 years (compared with <5 years), high area under curve of growth hormone (GH-AUC) after 75 g oral glucose tolerance test (OGTT) (compared with low GH-AUC patients), and high IGF-1 SDS group (compared with low IGF-1 SDS group) were significantly reduced (all P < 0.05). Serum asprosin levels in acromegaly patients were negatively correlated with the course of acromegaly, IGF-1 SDS, nadir growth hormone value (GH-Nadir), and GH-AUC after OGTT. Multiple stepwise linear regression indicated that acromegaly was an independent influencing factor of serum asprosin levels. According to serum asprosin levels tertiles, the risk of acromegaly in the lowest group was 2.67 times higher than the highest group (OR ＝ 3.665, 95% CI 1.677 ∼ 8.007, P=0.001), and the increased risk of the lowest group still existed after adjusting for gender, age, BMI, and TC (Model 2).

CONCLUSIONS

Serum asprosin levels in acromegaly patients are lowered, which may be related to increased blood glucose and reduced body fat mass caused by long-term high GH levels exposure.

Asprosin: A Novel Player in Metabolic Diseases

Asprosin, a novel glucogenic adipokine, is encoded by two exons (exon 65 and exon 66) of the gene Fibrillin 1 (FBN1) and mainly synthesized and released by white adipose tissue during fasting. Asprosin plays a complex role in the central nervous system (CNS), peripheral tissues, and organs. It is involved in appetite, glucose metabolism, insulin resistance (IR), cell apoptosis, etc. In this review, we will summarize the newly discovered roles of asprosin in metabolic diseases including diabetes, obesity, polycystic ovarian syndrome (PCOS), and cardiovascular disease (CVD), which may contribute to future clinical diagnosis and treatment.

Can novel adipokines, asprosin and meteorin-like, be biomarkers for malignant mesothelioma?

Malignant mesothelioma (MM) is a rare tumor of serous surfaces that has a poor prognosis. Cancer is a multistage process by which cells undergo metabolic and behavioral changes that cause excessive and untimely proliferation. Asprosin (ASP) and meteorin-like (METRNL) are two peptides associated with glucose and energy metabolism. We used immunohistochemistry to investigate whether these peptides could be biomarkers for diagnosis and treatment of MM. We reviewed 30 cases of MM and 30 cases of reactive mesothelial hyperplasia (RMH); we used the cases with RMH as control group. The specimens were examined using immunohistochemical staining for ASP and METRNL. ASP and METRNL immunoreactivity was more prominent in the MM specimens than the RMH specimens. Therefore, ASP and METRNL potentially could be used as markers for differentiating MM from benign diseases.

Decreased Blood Asprosin in Hyperglycemic Menopausal Women as a Result of Whole-Body Cryotherapy Regardless of Metabolic Syndrome

Endocrine dysfunction often occurs in metabolic syndrome (MetS), resulting in hyperglycemia and atherogenic blood lipid profile disorders. Asprosin is a newly discovered glucose-regulating hormone. The study aim was to determine whether the application of whole-body cryotherapy (WBC) affects asprosin and selected adipocytokines as well as insulin resistance in menopausal women with metabolic disorders. A total of 37 menopausal women were exposed to 20 WBC (-130 °C, 3 min). Blood glucose, asprosin, irisin, leptin, adiponectin, and insulin were measured before and after 20 WBC treatments, after which a homeostasis model assessment of insulin resistance (HOMA-IR) and atherogenic index of plasma (AIP) were calculated. The results were analyzed in the MetS group compared to the controls (CON) without MetS, and in the hyperglycemic (HG) group compared to the normoglycemic group (NG). After 20 WBC, a significant reduction (p < 0.05) in asprosin concentration was found in the MetS, HG, and CON groups, and a significant decrease (p < 0.05) in glucose concentration was noted in the HG group. Changes in asprosin concentration positively correlated with changes in glucose concentration. Asprosin concentration before WBC correlated positively with metabolic disorder risk factor levels, and the change in asprosin concentration after 20 WBC correlated negatively with metabolic disorder risk factor levels: fasting glucose, AIP, and the leptin/adiponectin index. Research indicates the possibility of using WBC in supporting metabolic disorders, type 2 diabetes (T2DM), and insulin resistance.