Increased circulating full-length betatrophin levels in drug-naïve metabolic syndrome

Effects of irisin and exercise on adropin and betatrophin in a new metabolic syndrome model

Metabolic syndrome (MetS) is a prevalent public health problem. Uric acid (UA) is increased by MetS. We investigated whether administration of UA and 10% fructose (F) would accelerate MetS formation and we also determined the effects of irisin and exercise. We used seven groups of rats. Group 1 (control); group 2 (sham); group 3 (10% F); group 4 (1% UA); group 5 (2% UA); group 6 (10% F + 1% UA); and Group 7, (10% F + 2% UA). After induction of MetS (groups 3 -7), Group 3 was divided into three subgroups: 3A, no further treatment; 3B, irisin treatment; 3C, irisin treatment + exercise. Group 4, 1% UA, which was divided into three subgroups: 4A, no further treatment; 4B, irisin treatment; 4C, Irisin treatment + exercise. Group 5, 2% UA, which was divided into three subgroups: 5A, no further treatment; 5B, irisin treatment; 5C, irisin treatment + exercise. Group 6, 10% F + 1% UA, which was divided into three subgroups: 6A, no further treatment; 6B, irisin treatment; 6C, irisin treatment + exercise. Group 7, 10% F + 2% UA, which was divided into three subgroups: 7A, no further treatment; 7B, irisin treatment; 7C, irisin treatment + exercise., İrisin was administered 10 ng/kg irisin intraperitoneally on Monday, Wednesday, Friday, Sunday each week for 1 month. The exercise animals (in addition to irisin treatment) also were run on a treadmill for 45 min on Monday, Wednesday, Friday, Sunday each week for 1 month. The rats were sacrificed and samples of liver, heart, kidney, pancreas, skeletal muscles and blood were obtained. The amounts of adropin (ADR) and betatrophin in the tissue supernatant and blood were measured using an ELISA method. Immunohistochemistry was used to detect ADR and betatrophin expression in situ in tissue samples. The duration of these experiments varied from 3 and 10 weeks. The order of development of MetS was: group 7, 3 weeks; group 6, 4 weeks; group 5, 6 weeks; group 4, 7 weeks; group 3, 10 weeks. Kidney, liver, heart, pancreas and skeletal muscle tissues are sources of adropin and betatrophin. In these tissues and in the circulation, adropin was decreased significantly, while betatrophin was increased significantly due to MetS; irisin + exercise reversed this situation. We found that the best method for creating a MetS model was F + UA2 supplementation. Our method is rapid and simple. Irisin + exercise was best for preventing MetS.

Betatrophin is downregulated in pregnant women with a history of RYGB operation and a high risk of postprandial hypoglycaemia

Betatrophin is a liver and adipose tissue-derived protein which has recently been linked to glucose metabolism. So far, no data exist about the role of betatrophin in pregnant women with a history of Roux-En-Y gastric bypass (RYGB) operation with a high risk of postprandial hypoglycaemia. In this prospective clinical study, an oral glucose tolerance test (OGTT) and an intravenous glucose tolerance test (IVGTT) were performed between the 24th and 28th week of pregnancy and 3–6 months post-partum in a cohort of obese and normal-weight pregnant women, as well as in women with a history of RYGB operation. In the cohort of pregnant women with RYGB and exaggerated risk of postprandial hypoglycaemic events, basal and dynamic betatrophin levels during the OGTT were lower than in the obese or normal-weight pregnant women (basal levels: 13.66 ± 5.88 vs. 19.03 ± 4.15 vs. 15.68 ± 6.48, p = 0.016; OGTT 60′: 13.33 ± 5.40 vs. 17.37 ± 3.16 vs. 15.84 ± 4.99, p = 0.030). During the OGTT, basal and dynamic betatrophin levels at 60′ were positively associated with glucose levels at 60 min (r = 0.55, p = 0.01 and r = 0.45, p = 0.039). This positive association was followed by significant hypoglycaemic events in the RYGB group. It was only in the RYGB group that betatrophin was negatively related to the disposition index (rho = -0.53, p = 0.014). After pregnancy there was a decrease in basal and stimulated betatrophin levels during the OGTT in all three patient groups. In comparison to normal-weight and obese pregnant women, women with a history of RYGB operation and a high risk of postprandial hypoglycaemic events have lower levels of betatrophin. This indicate a mechanistic role in order to decrease the risk of postprandial hypoglycaemia in this specific cohort.

Bacteria-Derived Recombinant Human ANGPTL8/Betatrophin Significantly Increases the Level of Triglyceride

ANGPTL8/Betatrophin has been implicated in the regulation of both glucose and triglyceride metabolism. However, its role in regulating glucose metabolism by promoting β cell proliferation remains controversial, and its physiological functions and molecular targets are largely unknown. Hence, it is of great importance to make recombinant protein and test its effects on β cell mass directly. In this study, the mature form gene of human ANGPTL8/betatrophin was obtained through chemical synthesis on to the vector pUCE, and the fusion protein was expressed in the Transetta (DE3)/pEASY-E2-betatrophin strain. The inclusion bodies were solubilized in urea and purified by Ni–NTA affinity chromatography. The yield of purified ANGPTL8/betatrophin was approximately 20 mg per liter of culture medium. In vitro studies revealed that the recombinant ANGPTL8/betatrophin had no proliferation effect on MIN6 cells but promoted TG levels in HepG2 cells. This method to generate bioactive ANGPTL8/betatrophin is a simple, practical and user-friendly protocol.

Higher circulating levels of ANGPTL8 are associated with body mass index, triglycerides, and endothelial dysfunction in patients with coronary artery disease

Bac Coronary artery disease (CAD) is the leading cause of death worldwide and most commonly develops as a result of atherosclerosis. ANGPTL8 is a secreted adipokine that regulates lipid metabolism and is associated with cardiometabolic diseases, including type 2 diabetes and CAD. However, the association between circulating ANGPTL8 levels and CAD is inconsistent among studies and the mechanism by which ANGPTL8 contributes to CAD development remains poorly understood. Here we sought to evaluate the relationship between ANGPTL8 levels and endothelial dysfunction and adipose tissue inflammation in CAD patients. Concentrations of ANGPTL8, adiponectin, TNF-α, IL6, hsCRP, ICAM-1, and VCAM-1 were measured by ELISA in serum samples from 192 CAD patients diagnosed with stenosis > 50% in at least one coronary artery by angiography and 71 individuals with normal heart function. Serum ANGPTL8 levels were significantly higher in CAD patients compared to controls (83.84 ± 23.25 ng/mL vs. 50.45 ± 17.73; p < 0.001), independent of adjustment for age, sex, BMI, smoking and statin use. ANGPTL8 could also differentiate CAD patients from controls with 82.3% specificity and 81.4% sensitivity (p < 0.001). Adiponectin levels were lower in CAD patients, while ICAM-1, VCAM-1, TNF-α, IL6, and hsCRP levels were higher compared to non-CAD controls (all p < 0.001). ANGPTL8 levels were associated with BMI in controls and with BMI, TG, and ICAM-1 in CAD patients. The presence of elevated ANGPTL8 levels in CAD patients and independent association with TG and ICAM-1 suggest a possible role related to endothelial dysfunction in the pathogenesis of atherosclerosis.

Circulating ANGPTL8 Is Associated with the Presence of Metabolic Syndrome and Insulin Resistance in Polycystic Ovary Syndrome Young Women

Background

ANGPTL8 has been reported to be a regulator of lipid metabolism, and it is associated with insulin resistance (IR) and metabolic syndrome (MetS). We investigated whether ANGPTL8 plays a role in MetS.

Methods

ANGPTL8 and adiponectin concentrations were measured in PCOS patients with or without MetS and in their corresponding healthy controls. The association of circulating ANGPTL8 with adiponectin and other parameters was also examined.

Results

Circulating ANGPTL8 concentrations were higher in PCOS women with MetS than in those without MetS and in the controls (P < 0.01). ANGPTL8 was positively correlated with age, BMI, FAT%, WHR, SBP, TG, FBG, HbA1c, Fins, and HOMA-IR (all P < 0.01) in the study populations and negatively associated with adiponectin and M-values (P < 0.001). In addition, ANGPTL8 was positively correlated with PRL, LH, TEST, and FAI and negatively correlated with SHBG (all P < 0.01). ROC curve analyses showed that the AUC_MetS was 0.87 (P < 0.001), with a sensitivity of 92.4% and specificity of 75.4%, and the AUC_IR was 0.82 (P < 0.01), with a sensitivity of 76.4% and specificity of 75.6%.

Conclusion

ANGPTL8 levels progressively decrease from PCOS patients with MetS to those without MetS and may be a serum marker associated with the degree of metabolic disorders.

Effects of a diet with or without physical activity on angiopoietin-like protein 8 concentrations in overweight/obese patients with newly diagnosed type 2 diabetes: a randomized controlled trial

Angiopoietin-like protein 8 (ANGPTL8) is a newly discovered adipokine plays an important role in energy homoeostasis, obesity and type 2 diabetes (T2D). Although lifestyle modification in obesity and T2D is known to offer metabolic benefits, there is paucity of comprehensive data on change in ANGPTL8. We investigated the effect of lifestyle intervention on ANGPTL8 concentrations. 384 obese/overweight adults with newly diagnosed T2D were randomly assigned (1:1:1) to diet (n = 128), diet + activity (n = 128) or usual care (control, n = 128) groups. All patients received usual care. Besides, the diet group received a calorie-restricted diet aiming for a weight loss of 5-10%. The diet + activity group additionally received a pedometer-based walking program. Primary outcome was change in ANGPTL8 concentration at 6 months. Data were analyzed according to intention-to-treat. From baseline to 6 months, the median ANGPTL8 level changed from 804.38 pg/mL to 792.86 pg/mL in control group. Compared with control, ANGPTL8 decreased with diet (baseline-adjusted between-group difference was -121.00 pg/mL, 95% CI -177.47 to -64.53; p < 0.0001) and diet + activity (-126.16 pg/mL, -181.21 to -71.11; p < 0.0001). There was no greater effect of diet + activity compared with diet (-5.16 pg/mL, -53.63 to 43.31; p = 0.8348). Both effects disappeared after adjusting for change in body fat, but did not differ significantly when adjusting for physical activity. A 6-month intervention inducing weight loss by a calorie-restricted diet or diet + activity, resulted in significant decrease on ANGPTL8 concentration. These effects were established by change in total body fat, and not by change in physical activity.

Triglyceride-mediated influence of serum angiopoietin-like protein 8 on subclinical atherosclerosis in type 2 diabetic patients: results from the GDMD study in China

Background

Hypertriglyceridemia, insulin resistance and hyperglycemia are risk factors for atherosclerosis in type 2 diabetes. Angiopoietin-like protein 8 (ANGPTL8) is a newly identified liver-derived hormone related to these risk factors. Hence, we aimed to explore the correlations between serum levels of ANGPTL8 and subclinical atherosclerosis in type 2 diabetes.

Methods

We measured serum ANGPTL8, blood lipids, blood glucose, common carotid artery Intima-Media Thickness (c-IMT) and calculated homeostasis model assessment of insulin resistance in (1) control subjects (n = 100), (2) type 2 diabetic patients without subclinical atherosclerosis (n = 100), and (3) type 2 diabetic patients with subclinical atherosclerosis (n = 100).

Results

Serum levels of ANGPTL8 and triglyceride (TG) were significantly increased in type 2 diabetic patients with subclinical atherosclerosis as compared with type 2 diabetic patients without subclinical atherosclerosis and control subjects (P < 0.001). ANGPTL8 was positively associated with age, TG, diabetes duration, and c-IMT in type 2 diabetes. Logistic regression analysis revealed that ANGPTL8 had higher odds of having subclinical atherosclerosis [odds ratio (OR) 2.90, 95% confidence interval (CI) 1.48–5.70, P = 0.002] in type 2 diabetes. Mediation analysis indicated that TG acted as a partial mediator in the relationship between ANGPTL8 and c-IMT.

Conclusions

TG partially mediates the positive relationship between ANGPTL8 and c-IMT. Our data provide the first evidence for a strong link between ANGPTL8 and subclinical atherosclerosis, suggesting ANGPTL8 to be a new biomarker for subclinical atherosclerosis in type 2 diabetes.

Angptl8 antisense oligonucleotide improves adipose lipid metabolism and prevents diet-induced NAFLD and hepatic insulin resistance in rodents

AIMS/HYPOTHESIS

Targeting regulators of adipose tissue lipoprotein lipase could enhance adipose lipid clearance, prevent ectopic lipid accumulation and consequently ameliorate insulin resistance and type 2 diabetes. Angiopoietin-like 8 (ANGPTL8) is an insulin-regulated lipoprotein lipase inhibitor strongly expressed in murine adipose tissue. However, Angptl8 knockout mice do not have improved insulin resistance. We hypothesised that pharmacological inhibition, using a second-generation antisense oligonucleotide (ASO) against Angptl8 in adult high-fat-fed rodents, would prevent ectopic lipid accumulation and insulin resistance by promoting adipose lipid uptake.

METHODS

ANGPTL8 expression was assessed by quantitative PCR in omental adipose tissue of bariatric surgery patients. High-fat-fed Sprague Dawley rats and C57BL/6 mice were treated with ASO against Angptl8 and insulin sensitivity was assessed by hyperinsulinaemic-euglycaemic clamps in rats and glucose tolerance tests in mice. Factors mediating lipid-induced hepatic insulin resistance were assessed, including lipid content, protein kinase Cε (PKCε) activation and insulin-stimulated Akt phosphorylation. Rat adipose lipid uptake was assessed by mixed meal tolerance tests. Murine energy balance was assessed by indirect calorimetry.

RESULTS

Omental fat ANGPTL8 mRNA expression is higher in obese individuals with fatty liver and insulin resistance compared with BMI-matched insulin-sensitive individuals. Angptl8 ASO prevented hepatic steatosis, PKCε activation and hepatic insulin resistance in high-fat-fed rats. Postprandial triacylglycerol uptake in white adipose tissue was increased in Angptl8 ASO-treated rats. Angptl8 ASO protected high-fat-fed mice from glucose intolerance. Although there was no change in net energy balance, Angptl8 ASO increased fat mass in high-fat-fed mice.

CONCLUSIONS/INTERPRETATION

Disinhibition of adipose tissue lipoprotein lipase is a novel therapeutic modality to enhance adipose lipid uptake and treat non-alcoholic fatty liver disease and insulin resistance. In line with this, adipose ANGPTL8 is a candidate therapeutic target for these conditions.

Association of circulating ANGPTL 3, 4, and 8 levels with medical status in a population undergoing routine medical checkups: A cross-sectional study

Purpose

Angiopoietin-like proteins (ANGPTLs) 3, 4, and 8 reportedly contribute to progression of metabolic disease, a risk factor for cardiovascular disease (CVD). The purpose of this study was to investigate whether circulating ANGPTL levels are associated with CVD risk after adjustment for potential confounding factors.

Methods

We conducted a single center, cross-sectional study of 988 Japanese subjects undergoing routine health checks. Serum ANGPTL3, 4, and 8 levels were measured using an enzyme-linked immunosorbent assay. Using multiple regression analysis we evaluated potential association of circulating ANGPTL3, 4, and 8 levels with general medical status including age, sex, smoking, drinking, obesity, hypertension, impaired glycometabolism, dyslipidemia, hyperuricemia, hepatic impairment, chronic kidney disease, anemia, cardiac abnormality, and inflammation.

Results

Circulating ANGPTL3 levels were relatively high in health-related categories of hepatic impairment and inflammation. Circulating ANGPTL4 levels were also significantly high in impaired glycometabolism or hepatic impairment but decreased in inflammation. Finally, increased ANGPTL8 levels were observed in obesity, impaired glycometabolism and dyslipidemia. Particularly, increased levels of circulating ANGPTL8 were positively correlated with circulating triglycerides and LDL-cholesterol levels and inversely correlated with circulating HDL-cholesterol levels.

Conclusions

Circulating ANGPTL3, 4, and 8 levels reflect some risk factors for CVD development.