A dual role of lipasin (betatrophin) in lipid metabolism and glucose homeostasis: consensus and controversy

Circulating angiopoietin-like protein 8 (ANGPTL8) and steatotic liver disease related to metabolic dysfunction: an updated systematic review and meta-analysis

Background

Steatotic liver disease related to metabolic dysfunction is the most common cause of chronic liver disease globally. The spectrum of this condition includes steatosis and steatohepatitis and was previously referred to as non-alcoholic fatty liver disease (NAFLD) but has been renamed as metabolic dysfunction-associated fatty liver disease (MAFLD) and more recently as metabolic dysfunction-associated steatotic liver disease (MASLD). Angiopoietin-like protein 8 (ANGPTL8), also known as betatrophin or lipasin, regulates triglycerides and has emerged as a potential novel biomarker for steatosis/steatohepatitis. Therefore, this systematic review aimed to identify and synthesize the evidence on the possible association of circulating ANGPTL8 concentrations with NAFLD, MAFLD or MASLD.

Methods

PubMed/MEDLINE, Cochrane Library, EMBASE, and Web of Science were searched for studies published in English reporting circulating ANGPTL8 concentrations in adults with NAFLD or MAFLD or MASLD and controls. A meta-analysis was performed, reporting the standardized mean difference (SMD) of circulating ANGPTL8 concentrations between these two groups. Study quality and risk of bias were assessed using the NIH quality assessment tool and RoBANS 2, respectively.

Results

Of the 104 identified publications, eight studies were eligible for this systematic review, whilst seven were also eligible for meta-analysis (543 NAFLD or MAFLD cases vs. 352 controls). Circulating ANGPTL8 concentrations were significantly higher in patients with NAFLD or MAFLD compared with controls (SMD: 0.62, 95%CI: 0.28-0.97; p<0.001). Considerable heterogeneity was noted among these studies, with six studies having high risk of bias in at least one RoBANS 2 domain.

Conclusion

These findings present up-to-date comprehensive evidence indicating that adults with steatotic liver disease related to metabolic dysfunction exhibit higher circulating ANGPTL8 concentrations compared with controls. Given the need for novel screening/diagnostic biomarkers for steatosis/steatohepatitis, as well for additional drug targets, large and prospective studies are required to confirm this association and explore its temporal direction, particularly under the new MASLD diagnosis/term.

Alterations in serum concentrations of visfatin and betatrophin in dogs with diabetes mellitus

Canine diabetes mellitus (DM) is associated with hyperglycemia and hyperlipidemia. Visfatin and betatrophin are adipokines involved in the pathophysiology of insulin resistance and deranged lipid metabolism, and are also altered in obesity. We hypothesized that visfatin and betatrophin serum concentrations are altered in diabetic dogs, irrespective of their body condition. The study included 23 newly-diagnosed DM (NDDM) dogs, 34 insulin-treated DM (ITDM) dogs and 24 healthy dogs. Body condition score was determined and fasted serum samples were collected for measurement of betatrophin, visfatin and insulin serum concentrations. Visfatin concentrations (mean, 95% CI) were lower in overweight NDDM (4.5 ng/mL, 2.5-8.1, P=0.05) and ITDM (2.8 ng/mL 1.8-4.3, P=0.006) than healthy (7.7 ng/mL, 5.0-11.7) dogs, but were not different among lean dogs, and were negatively correlated to betahydroxybutyric acid in ITDM dogs (r=-0.59, P=0.05). Betatrophin concentrations were lower in NDDM (69 pg/mL, 43-112, P<0.001) and ITDM (53 pg/mL, 34-84, P<0.001) than healthy (267 pg/mL, 167-426) dogs. Among NDDM dogs, betatrophin concentrations were higher in those with concurrent liver disease (203 pg/mL, 49-844) than those with no evidence of liver disease (19 pg/mL, 4-90, P=0.007), and were negatively correlated with glucose concentrations (r=-0.44, P=0.04) and creatinine (r=-0.60, P=0.003). Insulin concentrations were not different among NDDM and healthy dogs. Among NDDM dogs, insulin concentrations were negatively correlated to concentrations of betahydroxybutyric acid (r=-0.65, P=0.002) and were lower in dogs with concurrent kidney disease (5.6 mU/L, 2.1-15.3) compared to those with no evidence of kidney disease (20.6 mU/L, 8.0-53.2, P=0.018). In conclusion, DM in dogs is associated with alteration in visfatin and betatrophin concentrations that are not resolved by insulin treatment.

Active-matrix extended-gate field-effect transistor array for simultaneous detection of multiple metabolites

With the deepening understanding of diseases, increasing attention has been paid to personalized healthcare and precise diagnosis, which usually depend on the simultaneous monitoring of multiple metabolites, therefore requiring biological sensing systems to possess high sensitivity, specificity, throughput, and instant monitoring capabilities. In this work, we demonstrated the active-matrix extended-gate field-effect transistor (AMEGFET) array that can perform instant analysis of various metabolites in small amounts of body fluids collected during routine physiological activities. The extended gate electrodes of the AMEGFETs comprise ordered mesoporous carbon fibers loaded with both oxidoreductase enzymes for specific metabolites and platinum nanoparticles. By selecting customized electrode combinations, the AMEGFET array can monitor the concentrations of metabolites closely associated with chronic diseases and lifestyles, such as glucose, uric acid, cholesterol, ethanol, and lactate. The switch function of AMEGFET not only simplifies the readout circuitry for large-scale arrays but also avoids the mutual interferences among sensing units. The high flexibility and scalability make the AMEGFET array widely applicable in establishing high-throughput sensing platforms for biomarkers, providing highly efficient technical support for proactive health and intelligent healthcare.

Osteopontin Levels in Maternal Serum, Cord Blood, and Breast Milk According to Gestational Diabetes Mellitus: A Case-Control Study

BACKGROUND/OBJECTIVES

The prevalence of gestational diabetes mellitus (GDM) is increasing, and GDM poses health risks for both mothers and newborns. This study investigated the association between GDM and two biomarkers, osteopontin (OPN) and betatrophin (ANGPTL8).

METHODS

This study involved face-to-face interviews with 165 participants-81 in the GDM group and 84 in the control group-to gather maternal-newborn data. Maternal serum OPN levels, along with cord serum OPN and ANGPTL8 levels, were measured at birth. OPN levels in breast milk were also measured between postnatal days 10-15. Statistical analysis included Student's t-test for comparing biomarker levels, chi-square tests for GDM incidence across OPN quartile levels, multiple logistic regression for assessing GDM frequency by OPN quartile levels, and the Pearson correlation coefficient to explore relationships between biomarker levels and maternal-newborn characteristics.

RESULTS

No significant differences in cord OPN or ANGPTL8 levels were detected between the groups. However, the OPN levels in maternal serum and breast milk were greater in the GDM group than in the control group. We found an association between increasing maternal serum and breast milk OPN levels in quartile groups and the risk of GDM. Additionally, there was a moderate correlation between cord OPN and both maternal serum OPN (r = 0.45) and breast milk OPN (r = 0.43).

CONCLUSIONS

The differences in OPN levels between the GDM and control groups suggest that OPN may reflect metabolic changes associated with GDM, possibly as a consequence of the condition itself or its treatment. Further research is necessary to validate these findings and uncover the underlying mechanisms involved.

A unified model for regulating lipoprotein lipase activity

The regulation of triglyceride (TG) tissue distribution, storage, and utilization, a fundamental process of energy homeostasis, critically depends on lipoprotein lipase (LPL). We review the intricate mechanisms by which LPL activity is regulated by angiopoietin-like proteins (ANGPTL3, 4, 8), apolipoproteins (APOA5, APOC3, APOC2), and the cAMP-responsive element-binding protein H (CREBH). ANGPTL8 functions as a molecular switch, through complex formation, activating ANGPTL3 while deactivating ANGPTL4 in their LPL inhibition. The ANGPTL3-4-8 model integrates the roles of the aforementioned proteins in TG partitioning between white adipose tissue (WAT) and oxidative tissues (heart and skeletal muscles) during the feed/fast cycle. This model offers a unified perspective on LPL regulation, providing insights into TG metabolism, metabolic diseases, and therapeutics.

Branched-chain amino acids promote occurrence and development of cardiovascular disease dependent on triglyceride metabolism via activation of the mTOR/SREBP-1/betatrophin pathway

Branched-chain amino acid (BCAA) metabolism is associated with triglyceride (TG) metabolism and the development of cardiovascular disease (CVD). However, the underlying mechanism remains uncertain. This study included 1302 subjects and followed for 4-5 years. A hyperbranched-chain aminoacidemia rat model was induced by high fructose diet (HFTD). The relationship between BCAAs and TG level and its regulatory mechanism was investigated in vitro. As results, as baseline BCAA percentile increased, subjects had higher prevalence and incidence of T2DM, NAFLD, and CVD risk (P < 0.05). In animal model, the accumulation of BCAAs and TG and betatrophin expression were significantly elevated in the HFTD group when comparing with those in the SD group(P < 0.05). Immunofluorescence and Masson's trichrome staining revealed that the area of interstitial fibrosis was significantly increased in the HFTD group compared with control group. Met treatment significantly decreased TG levels and betatrophin expression and reversed myocardial fibrosis (P < 0.05). In vitro, LO2 cells, stimulated with 0.1-5 mM BCAAs, displayed a significant dose-dependent increase in betatrophin expression (P < 0.05). And 5 mM BCAAs stimulation significantly increased the p-mTOR and SREBP-1 expression (P < 0.05). However, this effect could be reversed by using the corresponding inhibitor or siRNAs. In conclusions, BCAAs promote occurrence and development of cardiovascular disease dependent on TG metabolism via activation of the mTOR/SREBP-1/betatrophin pathway. The study provides a new theory for the pathogenesis of CVD caused by amino acid metabolism disorders.

Silencing ANGPTL8 reduces mouse preadipocyte differentiation and insulin signaling

ANGPTL8, expressed mainly in the liver and adipose tissue, regulates the activity of lipoprotein lipase (LPL) present in the extracellular space and triglyceride (TG) metabolism through its interaction with ANGPTL3 and ANGPTL4. Whether intracellular ANGPTL8 can also exert effects in tissues where it is expressed is uncertain. ANGPTL8 expression was low in preadipocytes and much increased during differentiation. To better understand the role of intracellular ANGPTL8 in adipocytes and assess whether it may play a role in adipocyte differentiation, we knocked down its expression in normal mouse subcutaneous preadipocytes. ANGPTL8 knockdown reduced adipocyte differentiation, cellular TG accumulation and also isoproterenol-stimulated lipolysis at day 7 of differentiation. RNA-Seq analysis of ANGPTL8 siRNA or control siRNA transfected SC preadipocytes on days 0, 2, 4 and 7 of differentiation showed that ANGPTL8 knockdown impeded the early (day 2) expression of adipogenic and insulin signaling genes, PPARγ, as well as genes related to extracellular matrix and NF-κB signaling. Insulin mediated Akt phosphorylation was reduced at an early stage during adipocyte differentiation. This study based on normal primary cells shows that ANGPTL8 has intracellular actions in addition to effects in the extracellular space, like modulating LPL activity. Preadipocyte ANGPTL8 expression modulates their differentiation possibly via changes in insulin signaling gene expression.

Alterations in serum concentrations of visfatin and betatrophin in dogs with hypothyroidism

BACKGROUND

Hypothyroidism in dogs is associated with obesity and altered lipid and carbohydrate metabolism. The adipokines, visfatin, and betatrophin, affect glucose tolerance. Betatrophin is involved in lipid regulation.

HYPOTHESIS

Visfatin and betatrophin serum concentrations are altered in hypothyroid dogs.

ANIMALS

Dogs with naturally occurring hypothyroidism (n = 25) and healthy dogs (n = 25).

METHODS

Insulin, visfatin, and betatrophin serum concentrations were measured in all dogs and 19 of the hypothyroid dogs after 30 days of thyroxine treatment. Body condition score (BCS) was determined (1-9 scale).

RESULTS

Visfatin concentrations were lower in hypothyroid compared with healthy dogs (mean, 95% confidence interval [CI]; 2.0 ng/mL, 1.2-3.3 vs 5.1 ng/mL, 3.3-7.8; P = .004) and increased post-treatment (3.1 ng/mL, 1.9-4.9 vs 2.6 ng/mL, 1.6-4.1; P = .05). Betatrophin concentrations were lower in lean to normal (body condition score [BCS], 3-5) hypothyroid dogs compared to lean to normal healthy dogs (52 pg/mL, 9-307 vs 597 pg/mL, 216-1648; P = .03), but were not different between overweight (BCS, 6-9) hypothyroid and healthy dogs (341 pg/L, 168-695 vs 178 pg/mL, 77-415; P = .26), and decreased post-treatment in overweight dogs (206 pg/mL, 87-488 vs 268 pg/mL, 112-640; P = .004). Visfatin concentrations were higher in overweight compared with lean to normal dogs (4.7 ng/mL, 3.3-6.6 vs 2.2 ng/mL, 1.2-4.2; P = .04). Betatrophin concentrations were positively correlated with BCS (r = .47, P = .02) and insulin concentrations (r = .48, P = .03) in hypothyroid dogs and negatively correlated with BCS (r = -.47, P = .02) and thyroid stimulating hormone concentrations (r = -.56, P = .01) in healthy dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Hypothyroidism in dogs is associated with alterations in visfatin and betatrophin concentrations that partially resolve with thyroxine treatment.

Investigation of the relationship between betatrophin and certain key enzymes involved in carbohydrate and lipid metabolism in insulin-resistant mice

OBJECTIVES

The present study sought to examine the relationship of betatrophin with certain key enzymes, namely lactate dehydrogenase-5 (LDH5), citrate synthase (CS), and acetyl-CoA carboxylase-1 (ACC1), in insulin-resistant mice.

METHODS

Eight-week-old male C57BL6/J mice were used in this study (experimental group n=10 and control group n=10). S961 was administered using an osmotic pump to induce insulin resistance in the mice. The betatrophin, LDH5, CS, and ACC1 expression levels were determined from the livers of the mice using the real-time polymerase chain reaction (RT-PCR) method. Moreover, biochemical parameters such as the serum betatrophin, fasting glucose, insulin, triglyceride, total cholesterol, and high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol levels were analyzed.

RESULTS

The betatrophin expression and serum betatrophin (p=0.000), fasting glucose, insulin, triglyceride (p≤0.001), and total cholesterol (p=0.013) levels were increased in the experimental group. In addition, the CS gene expression level was statistically significantly decreased in the experimental group (p=0.01). Although strong correlation was found between the expression and serum betatrophin and triglyceride levels, no correlation was found between the betatrophin gene expression and the LDH5, ACC1, and CS gene expression levels.

CONCLUSIONS

The betatrophin level appears to play an important role in the regulation of triglyceride metabolism, while insulin resistance increases both the betatrophin gene expression and serum levels and decreases the CS expression level. The findings suggest that betatrophin may not regulate carbohydrate metabolism through CS and LDH5 or lipid metabolism directly through the ACC1 enzyme.

Targeted Metabolomics Analysis of Individuals Carrying the ANGPTL8 R59W Variant

ANGPTL8 is recognized as a regulator of lipid metabolism through its role in inhibiting lipoprotein lipase activity. ANGPTL8 gene variants, particularly rs2278426 leading to the R59W variant in the protein, have been associated with lipid traits in various ethnicities. We aimed to use metabolomics to understand the impact of the ANGPTL8 R59W variant on metabolites in humans. We used the Biocrates-p400 kit to quantify 408 plasma metabolites in 60 adult male Arab individuals from Kuwait and identify differences in metabolite levels between individuals carrying reference genotypes and those with carrier genotypes at ANGPTL8 rs2278426. Individuals with carrier genotypes (CT+TT) compared to those carrying the reference genotype (CC) showed statistically significant differences in the following metabolites: acylcarnitine (perturbs metabolic pathways), phosphatidylcholine (supports liver function and cholesterol levels), cholesteryl ester (brings chronic inflammatory response to lipoprotein depositions in arteries), α-aminoadipic acid (modulates glucose homeostasis), histamine (regulates glucose/lipid metabolism), sarcosine (links amino acid and lipid metabolism), diacylglycerol 42:1 (regulates homeostasis of cellular lipid stores), and lysophosphatidylcholine (regulates oxidative stress and inflammatory response). Functional aspects attributed to these metabolites indicate that the ANGPTL8 R59W variant influences the concentrations of lipid- and inflammation-related metabolites. This observation further highlights the role of ANGPTL8 in lipid metabolism.

Evaluation of Adiponectin and ANGPTL8 in Women With Metabolic Syndrome in the Madinah Region of Saudi Arabia

OBJECTIVE

 "Metabolic syndrome" (MetS) is a set of abnormalities that may be risk factors for cardiovascular disease (CVD) and diabetes. The current study sought to (1) determine MetS prevalence and (2) examine Adiponectin and ANGPTL8 levels in connection to MetS components and CVDs and diabetes risk in females with MetS.

METHODS

A total of 350, 20-35-year-old Saudi females were studied. Waist circumference (WC), body mass index (BMI), glucose, HbA1c, insulin, lipid profiles, and blood pressure (BP) were examined for MetS. ANGPTL8 and Adiponectin were also measured.

RESULTS

The patients were classified into two groups, namely MetS and non-MetS, according to the criteria established by the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATPIII). We examined biomarker and anthropometric results between these groups. One hundred forty-four of 350 female participants (41.2%) had MetS, with a mean age of 30.5 years. Fasting blood glucose (FBG), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), ANGPTL8, adiponectin, and insulin resistance (IR) were statistically significant differences observed between the two groups. BP, BMI, WC, and Atherogenic Index of Plasma (AIP) all changed significantly (P ≤0.05). Correlation studies linked MetS components to higher ANGPTL-8 and reduced adiponectin. The levels of ANGPTL8 were shown to be influenced by the increase in FBG, TG, BP, IR, and AIP (P < 0.05). Factors such as FBG, BMI, WC, and IR have been found to have an inverse relationship with adiponectin levels.

CONCLUSION

41.2% out of 350 Saudi females at Taibah University in the Madinah region had MetS, medium CVD risk, and slightly elevated BMI, TG, WC, and BP. To lower their risk of CVD and diabetes later in life, overweight young women should be evaluated for MetS. FBG and TG were substantially associated with ANGPTL8 while reducing adiponectin was associated with elevated TG and BP. Our findings may lead to ANGPTL8 and adiponectin's possible predictive function for CVD in early MetS in females.

Plasma and aqueous levels of subfatin, preptin and betatrophin in patients with diabetic retinopathy

AIM

To examine subfatin, preptin and betatrophin levels in plasma and aqueous in patients with diabetes mellitus (DM) (with and without retinopathy).

MATERIAL AND METHOD

Sixty patients, who were similar in terms of age and gender, and were scheduled for operation due to cataract, were included in the study. The patients were divided into three groups as Group C (20 weeks without diabetes and comorbidity), Group DM (20 patients with DM but no retinopathy) and Group DR (20 patients with diabetic retinopathy). The preoperative body mass index (BMI), fasting plasma glucose, HbA1c, lipid profile levels of all patients in the groups were examined. Blood samples were also taken for plasma subfatin, preptin and betatrophin levels. At the beginning of the cataract surgery, 0.1 ml of aqueous fluid was taken from the anterior chamber. Plasma and aqueous subfatin, preptin and betatrophin levels were analyzed by ELISA (enzyme-linked immunosorbent assays) method.

RESULTS

In our study results, there was a significant difference in BMI, fasting plasma glucose and hemoglobin A1c levels (p < 0.05 for all parameters). Plasma and aqueous subfatin levels were higher in Group DR compared to Group C (p < 0.001, p = 0.036, respectively). Plasma and aqueous preptin levels were higher in group DR and group DM than in group C (p = 0.001, p = 0.002, p < 0.001, p = 0.001, respectively). Plasma and aqueous betatrophin levels were higher in Group DR compared to group C (p = 0.001, p = 0.010, respectively).

CONCLUSION

Subfatin, preptin and betatrophin molecules may have an important role in the pathogenesis of diabetic retinopathy.

Dynamic alteration of plasma levels of betatrophin in younger female onset obesity post acute moderate-intensity exercise training

Obesity is a global metabolic disease anchored by a lack of physical activity lipid disturbances. Hitherto, betatrophin is a potential liver-derived hormone that regulates lipid metabolism. A total of 26 selected onset obese individuals (BMI range ± 28-31) were enrolled in this study and given moderate-intensity exercise. Importantly, our data show that acute moderate-intensity interval exercise (MIIE) and acute moderate-intensity continue to exercise (MICE) for 40 min significantly decrease the plasma level of full-length betatrophin respectively (174.18 ± 48.19 ng/mL; 182.31 ± 52.69 ng/mL), compared to the placebo (283.97 ± 32.23 ng/mL) post 10 min and 6 h exercise treatment (p ≤ 0.05). The plasma level of betatrophin was significantly and negatively correlated with BMI (r = - 0.412, p = 0.037), fasting blood glucose (r = - 0.390, p = 0.049), and positively correlated with VO_2max (r = 0.456, p = 0.019). In addition, the linear and ordinal logistic regression analysis shows that betatrophin, is a potential predictor for BMI [estimate value = 0.995, p = 0.037 and OR (95 % CI) = 0.992 (0.0984-1.00), p = 0,048]. In summary, our data demonstrate that the circulating levels of betatrophin were decreased after acute moderate-intensity exercise training.

An updated ANGPTL3-4-8 model as a mechanism of triglyceride partitioning between fat and oxidative tissues

In mammals, triglyceride (TG), the main form of lipids for storing and providing energy, is stored in white adipose tissue (WAT) after food intake, while during fasting it is routed to oxidative tissues (heart and skeletal muscle) for energy production, a process referred to as TG partitioning. Lipoprotein lipase (LPL), a rate-limiting enzyme in this fundamental physiological process, hydrolyzes circulating TG to generate free fatty acids that are taken up by peripheral tissues. The postprandial activity of LPL declines in oxidative tissues but rises in WAT, directing TG to WAT; the reverse is true during fasting. However, the molecular mechanism in regulating tissue-specific LPL activity during the fed-fast cycle has not been completely understood. Research on angiopoietin-like (ANGPTL) proteins (A3, A4, and A8) has resulted in an ANGPTL3-4-8 model to explain the TG partitioning between WAT and oxidative tissues. Food intake induces A8 expression in the liver and WAT. Liver A8 activates A3 by forming the A3-8 complex, which is then secreted into the circulation. The A3-8 complex acts in an endocrine manner to inhibit LPL in oxidative tissues. WAT A8 forms the A4-8 complex, which acts locally to block A4's LPL-inhibiting activity. Therefore, the postprandial activity of LPL is low in oxidative tissues but high in WAT, directing circulating TG to WAT. Conversely, during fasting, reduced A8 expression in the liver and WAT disables A3 from inhibiting oxidative-tissue LPL and restores WAT A4's LPL-inhibiting activity, respectively. Thus, the fasting LPL activity is high in oxidative tissues but low in WAT, directing TG to the former. According to the model, we hypothesize that A8 antagonism has the potential to simultaneously reduce TG and increase HDL-cholesterol plasma levels. Future research on A3, A4, and A8 can hopefully provide more insights into human health, disease, and therapeutics.

Analysis of the Expression and Prognostic Potential of a Novel Metabolic Regulator ANGPTL8/Betatrophin in Human Cancers

The angiopoietin-like protein (ANGPTL) family members, except for the novel atypical member ANGPTL8/betatrophin, have been reported to participate in angiogenesis, inflammation and cancer. ANGPTL8/betatrophin is a metabolic regulator that is involved in lipid metabolism and glucose homeostasis. However, little is known about the expression and prognostic value of ANGPTL8/betatrophin in human cancers. In this study, we first conducted detailed analyses of ANGPTL8/betatrophin expression in cancer/normal samples via the Human Protein Atlas (HPA), Gene Expression Profiling Interactive Analysis (GEPIA), DriverDBv3, ENCORI and UALCAN databases. ANGPTL8/betatrophin showed high tissue specificity (enriched in the liver) and cell-type specificity (enriched in HepG2 and MCF7 cell lines). More than one databases demonstrated that the gene expression of ANGPTL8/betatrophin was significantly lower in cholangiocarcinoma (CHOL), breast invasive carcinoma (BRCA), lung adenocarcinoma (LUAD), lung squamous cell carcinoma (LUSC), uterine corpus endometrial carcinoma (UCEC), and significantly higher in kidney renal clear cell carcinoma (KIRC) compared with that in normal samples. However, the protein expression of ANGPTL8/betatrophin displayed opposite results in clear cell renal cell carcinoma (ccRCC)/KIRC. Based on the expression profiles, the prognostic value was evaluated with the GEPIA, DriverDBv3, Kaplan Meier plotter and ENCORI databases. Two or more databases demonstrated that ANGPTL8/betatrophin significantly affected the survival of KIRC, uterine corpus endometrial carcinoma (UCEC), pheochromocytoma and paraganglioma (PCPG) and sarcoma (SARC); patients with PCPG and SARC may benifit from high ANGPTL8/betatrophin expression while high ANGPTL8/betatrophin expression was associated with poor prognosis in KIRC and UCEC. Functional analyses with the GeneMANIA, Metascape and STRING databases suggested that ANGPTL8/betatrophin was mainly involved in lipid homeostasis, especially triglyceride and cholesterol metabolism; glucose homeostasis, especially insulin resistance; AMPK signaling pathway; PI3K/Akt signaling pathway; PPAR signaling pathway; mTOR signaling pathway; HIF-1 signaling pathway; autophagy; regulation of inflammatory response. ANGPTL8/betatrophin may be a promising prognostic biomarker and therapeutic target, thus providing evidence to support further exploration of its role in defined human cancers.

Association of Circulating ANGPTL8 Levels With Renal Dysfunction: A Case-Control Study

Background: Chronic kidney disease (CKD) is recognized as a major public health problem with high morbidity and mortality worldwide. Recently, angiopoietin-like protein 8 (ANGPTL8) was found to regulate lipid metabolism. Previous studies suggested that serum ANGPTL8 levels increased in patients with diabetes, especially in diabetic patients with albuminuria. This study aimed to investigate the association between circulating levels of ANGPTL8 and kidney function in the general population. Methods: The subjects were patients with renal dysfunction [estimated glomerular filtration rate (eGFR) <60/min/1.73 m²] from Risk Evaluation of cAncers in Chinese diabeTic Individuals: a lONgitudinal study (the REACTION study). Each case was matched by age, sex, and body mass index (BMI) with one control whose eGFR was ≥ 90 ml/min/1.73 m². The case and control groups were compared using a paired t-test. Binary logistic regression analysis was used to calculate the odds ratio (OR) of renal dysfunction (RD). Results: Among 135 case-control pairs, circulating ANGPTL8 levels were elevated in patients with RD compared to control subjects [799.96 (410.12-1086.44) vs. 609.58 (365.13-740.06) pg/ml, p < 0.05]. Partial correlations showed that ANGPTL8 levels were negatively correlated with eGFR (r = -0.26, p < 0.05). Multivariable-adjusted binary logistic regression analysis showed that elevated ANGPTL8 levels were associated with an increased risk of RD (OR in quartile 4 vs. 1, 3.80; 95% CI, 1.71-8.41). Interestingly, the association between ANGPTL8 levels and RD was consistent with the overall findings in both nondiabetic individuals (OR, 1.44; 95% CI, 1.09 to 1.91) and diabetic patients (OR, 2.71; 95% CI, 1.13-6.49) in the subgroup analyses. Furthermore, the estimates for this association were also significant in females (OR, 2.12; 95% CI, 1.33-3.37), individuals aged > 60 years (OR, 1.55; 95% CI, 1.16-2.07), individuals with a BMI <24 (OR, 1.66; 95% CI, 1.16-2.39), and individuals without hyperlipidaemia (OR, 1.61; 95% CI, 1.16-2.23) (all p-values <0.05). Conclusion: Elevated circulating ANGPTL8 levels were associated with increased risk of RD in the general population, especially among females, individuals aged > 60 years, individuals with a BMI < 24, individuals without diabetes mellitus, individuals with diabetes mellitus (DM), and individuals without hyperlipidaemia. This finding implies that ANGPTL8 may play a role in the pathological process of RD.

ANGPTL8 in metabolic homeostasis: more friend than foe?

ANGPTL8 is an important cytokine, which is significantly increased in type 2 diabetes mellitus (T2DM), obesity and metabolic syndrome. Many studies have shown that ANGPTL8 can be used as a bio-marker of these metabolic disorders related diseases, and the baseline ANGPTL8 level has also been found to be positively correlated with retinopathy and all-cause mortality in patients with T2DM. This may be related to the inhibition of lipoprotein lipase activity and the reduction of circulating triglyceride (TG) clearance by ANGPTL8. Consistently, inhibition of ANGPTL8 seems to prevent or improve atherosclerosis. However, it is puzzling that ANGPTL8 seems to have a directing function for TG uptake in peripheral tissues; that is, ANGPTL8 specifically enhances the reserve and buffering function of white adipose tissue, which may alleviate the ectopic lipid accumulation to a certain extent. Furthermore, ANGPTL8 can improve insulin sensitivity and inhibit hepatic glucose production. These contradictory results lead to different opinions on the role of ANGPTL8 in metabolic disorders. In this paper, the correlation between ANGPTL8 and metabolic diseases, the regulation of ANGPTL8 and the physiological role of ANGPTL8 in the process of glucose and lipid metabolism were summarized, and the physiological/pathological significance of ANGPTL8 in the process of metabolic disorder was discussed.

The Physiological Role of Irisin in the Regulation of Muscle Glucose Homeostasis

Irisin is a myokine that primarily targets adipose tissue, where it increases energy expenditure and contributes to the beneficial effects of exercise through the browning of white adipose tissue. As our knowledge has deepened in recent years, muscle has been found to be a major target organ for irisin as well. Several studies have attempted to characterize the role of irisin in muscle to improve glucose metabolism through mechanisms such as reducing insulin resistance. Although they are very intriguing reports, some contradictory results make it difficult to grasp the whole picture of the action of irisin on muscle. In this review, we attempted to organize the current knowledge of the role of irisin in muscle glucose metabolism. We discussed the direct effects of irisin on glucose metabolism in three types of muscle, that is, skeletal muscle, smooth muscle, and the myocardium. We also describe irisin’s effects on mitochondria and its interactions with other hormones. Furthermore, to consider the relationship between the irisin-induced improvement of glucose metabolism in muscle and systemic disorders of glucose metabolism, we reviewed the results from animal interventional studies and human clinical studies.

Circulating ANGPTL8 levels and risk of kidney function decline: Results from the 4C Study

Background

ANGPTL8, an important regulator of lipid metabolism, was recently proven to have additional intracellular and receptor-mediated functions. This study aimed to investigate circulating levels of ANGPTL8 and its potential association with the risk of kidney function decline in a cohort study.

Methods

We analysed 2,311 participants aged 40 years old and older from the China Cardiometabolic Disease and Cancer Cohort (4C) Study. Kidney function decline was defined as an estimated glomerular filtration rate (eGFR) less than 60 mL per minute per 1.73 m² of body surface area, a decrease in eGFR of ≥ 30% from baseline, chronic kidney disease (CKD)-related hospitalization or death, or end-stage renal disease. The association between baseline ANGPTL8 levels and kidney function decline was assessed using multivariable-adjusted Cox proportional hazards models, and inverse possibility of treatment weight (IPTW) was utilized to prevent overfitting.

Results

There were 136 (5.9%) cases of kidney function decline over a median of 3.8 years of follow-up. We found that serum ANGPTL8 levels at baseline were elevated in individuals with kidney function decline compared to those without kidney function decline during follow-up (718.42 ± 378.17 vs. 522.04 ± 283.07 pg/mL, p < 0.001). Compared with the first quartile, multivariable-adjusted hazard ratio (95% confidence intervals [CIs]) for kidney function decline was 2.59 (95% CI, 1.41–4.77) for the fourth ANGPTL8 quartile. Furthermore, compared with patients in the first ANGPTL8 quartile, those in the fourth ANGPTL8 quartile were more likely to report a higher stage of CKD (relative risk: 1.33; 95% CI, 1.01–1.74). The conclusions of the regression analyses were not altered in the IPTW models. Multivariable-adjusted restricted cubic spline analyses suggested a linear relationship of ANGPTL8 with kidney function decline (p for nonlinear trend = 0.66, p for linear trend < 0.001).

Conclusions

Participants with higher circulating ANGPTL8 levels were at increased risk for kidney function decline, highlighting the importance of future studies addressing the pathophysiological role of ANGPTL8 in CKD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-021-01317-3.

Angiopoietin-like proteins in atherosclerosis

Atherosclerosis, as a chronic inflammatory disease within the arterial wall, is a leading cause of morbidity and mortality worldwide due to its role in myocardial infarction, stroke and peripheral artery disease. Additional evidence is emerging that the angiopoietin-like (ANGPTL) family of proteins participate in the pathology of this disease process via endothelial dysfunction, inflammation, dyslipidemia, calcification, foam cell formation and platelet activation. This review summarizes current knowledge on the ANGPTL family of proteins in atherosclerosis related pathological processes. Moreover, the potential value of ANGPTL family proteins as predictive biomarkers in atherosclerosis is discussed. Given the attractive role of ANGPTL3, ANGPTL4, ANGPTL8 in atherosclerotic dyslipidemia via regulation of lipoprotein lipase (LPL), antisense oligonucleotide or/and monoclonal antibody-based inactivation of these proteins represent potential atherosclerotic therapies.

Circulating angiopoietin-like proteins in metabolic-associated fatty liver disease: a systematic review and meta-analysis

Background

Angiopoietin-like proteins (ANGPTLs) are closely related to insulin resistance and lipid metabolism, and may be a key in metabolic syndrome. Non-alcoholic fatty liver disease (NAFLD) (newly named metabolic-associated fatty liver disease (MAFLD)) is based on metabolic dysfunction. There may be some correlation between ANGPTLs and MAFLD, but the specific correlation is unclear. This study aims to explore the predictive role of ANGPTLs in MAFLD and its progression.

Methods

Seven databases (PubMed, EMBASE, Cochrane Library, CNKI, WANFANG, CBM and Clinicaltrials.gov) were searched with free terms and MeSH terms. The random-effects model was used to pool the data, and Standardized Mean Difference (SMD) and 95% confidence intervals (CI) were taken as the overall outcome. No language restrictions existed in the article selection. RevMan 5.3, Stata 16 and MetaXL software were applied to analyse the data and the GRADE system was utilized to assess the certainty of evidence.

Results

After reviewing 823 related articles, 13 studies (854 cases and 610 controls) met the inclusion criteria, and contributed to this meta-analysis. The results showed that circulating ANGPTL8 level was significantly elevated in the MAFLD group than in the healthy control group (SMD = 0.97 pg/mL, 95%CI: 0.77, 1.18). Conversely, there was no significant difference in the ANGPTL4 (SMD = 0.11 ng/mL, 95%CI: − 0.32, 0.54) and ANGPTL3 (SMD = − 0.95 ng/mL, 95%CI: − 4.38, 2.48) between the two groups. Subgroup analysis showed that: 1) the MAFLD group had significantly higher ANGPTL8 levels than the healthy control group in Asian and other races; 2) the ANGPTL8 levels in Body Mass Index (BMI) > 25 kg/m² patients with MAFLD were higher than those in the healthy control group; 3) the higher ANGPTL8 levels were observed in moderate to severe MAFLD group than the healthy control group. Meta-regression demonstrated that BMI might effectively explain the high heterogeneity. No significant publication bias existed (P > 0.05). The certainty of evidence was assessed as very low by the GRADE system.

Conclusions

The ANGPTLs may be related to MAFLD. The increased ANGPTL8 level may be positively correlated with different situations of MAFLD, which may act as a potential indicator to monitor the development trends.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-021-01481-1.

Circulating micro RNA-223 and angiopoietin-like protein 8 as biomarkers of gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is a serious health problem associated with both foetal and maternal complications. New biomarkers that can predict or help in the early diagnosis of GDM are needed to minimize the hazards of hyperglycaemia in pregnant women and their offspring. We hypothesised a link between levels of microRNA-223 (miRNA-223) and Angiopoietin-Like Protein 8 (ANGPTL8) and GDM.

MATERIALS AND METHODS

The study included 109 patients with confirmed early diagnosed GDM and 103 healthy control pregnant women in their second or third trimester. miRNA-223 and ANGPTL8 blood levels were assessed by real-time RT-PCR and sandwich ELISA, respectively, laboratory markers by standard methods.

RESULTS

There was a significant increase in mean [SD] miRNA-223 and ANGPTL8 in GDM (0.31 [0.06] relative units) and (692 [199] pg/ml), respectively, in the GDM women compared to healthy pregnant women (0.17[0.05] relative units) and (261 [127] pg/ml), respectively, P  < 0.001. miRNA-223 and ANGPTL8 correlated significantly with each other (r = 0.38, P  < 0.001) and with fasting, 1-h and 2-h postprandial blood glucose levels (all P ≤ 0.002) HbA1 c (P  < 0.025), total cholesterol (P < 0.01), LDL-C and triglycerides (both P ≤ 0.005). The ROC area under curve (AUC) (95%CI) was 0.94 (0.91-0.97) for ANGPTL8, 0.92 (0.88-0.96) for miRNA-223 and 0.97 (0.95 - 0.99) for their combination.

CONCLUSIONS

These findings support the hypothesis of involvement of both miRNA-223 and ANGPTL8 in the pathogenesis of GDM. The difference between levels in GDM patients and in control pregnant women indicates potential use for early diagnosis or prediction of GDM.

Correlation of serum betatrophin levels with disease severity and the emergence of insulin resistance in cirrhotic patients

Background

Insulin resistance (IR) is frequently associated with chronic liver disease. There has been an increased interest in betatrophin protein and its involvement in the compensatory response to IR. We aimed to investigate the correlation of serum betatrophin levels with disease severity and the emergence of IR in cirrhotic patients. This study included 27 cirrhotic patients and 30 healthy participants who served as a control group. IR was assessed by the Homeostasis Model Assessment (HOMA-IR). Serum insulin and betatrophin levels were measured using Enzyme-Linked Immunosorbent Assay (ELISA).

Results

IR was existing in 74% of cirrhotic patients (p < 0.001). Subjects with IR had higher serum betatrophin levels than those without IR (p = 0.04). Serum betatrophin levels were significantly higher in cirrhotic patients than controls (p < 0.001). In addition, Child-Pugh class C patients had higher serum betatrophin levels than those with Child-Pugh class B cirrhosis (p = 0.01). Moreover, the highest serum betatrophin levels were detected in patients with tense ascites followed by those with moderate and mild ascites (p = 0.01). In the cirrhosis group, serum betatrophin levels correlated positively with fasting blood glucose levels (p < 0.001), fasting insulin levels (p = 0.006), HOMA-IR (p = 0.006), Child-Pugh score (p = 0.023), MELD score (p < 0.001), and INR (p = 0.005), and correlated negatively with platelets count (p = 0.01).

Conclusion

Cirrhotic patients have higher serum betatrophin levels; moreover, these levels are positively correlated with disease severity as well as the emergence of insulin resistance.

The multi-faces of Angptl8 in health and disease: Novel functions beyond lipoprotein lipase modulation

Angiopoietin-like protein (ANGPTL) family members, mainly ANGPTL3, ANGPTL4 and ANGPTL8, are physiological inhibitors of lipoprotein lipase (LPL), and play a critical role in lipoprotein and triglyceride metabolism in response to nutritional cues. ANGPTL8 has been described by different names in various studies and has been ascribed various functions at the systemic and cellular levels. Circulating ANGPTL8 originates mainly from the liver and to a smaller extent from adipose tissues. In the blood, ANGPTL8 forms a complex with ANGPTL3 or ANGPTL4 to inhibit LPL in fed or fasted conditions, respectively. Evidence is emerging for additional intracellular and receptor-mediated functions of ANGPTL8, with implications in NFκB mediated inflammation, autophagy, adipogenesis, intra-cellular lipolysis and regulation of circadian clock. Elevated levels of plasma ANGPTL8 are associated with metabolic syndrome, type 2 diabetes, atherosclerosis, hypertension and NAFLD/NASH, even though the precise relationship is not known. Whether ANGPTL8 has direct pathogenic role in these diseases, remains to be explored. In this review, we develop a balanced view on the proposed association of this protein in the regulation of several pathophysiological processes. We also discuss the well-established functions of ANGPTL8 in lipoprotein metabolism in conjunction with the emerging novel extracellular and intracellular roles of ANGPTL8 and the implicated metabolic and signalling pathways. Understanding the diverse functions of ANGPTL8 in various tissues and metabolic states should unveil new opportunities of therapeutic intervention for cardiometabolic disorders.

Predictive values of ANGPTL8 on risk of all-cause mortality in diabetic patients: results from the REACTION Study

Background

Angiopoietin-like protein 8 (ANGPTL8), an important regulator of lipid metabolism, is increased in diabetes and is associated with insulin resistance. However, the role of ANGPTL8 in the outcomes of diabetic patients remains unclear. This study aimed to investigate circulating levels of ANGPTL8 in participants with and without diabetes and its potential associations with clinical outcomes in a 5 year cohort study.

Methods

Propensity-matched cohorts of subjects with and without diabetes from the Risk Evaluation of Cancers in Chinese Diabetic Individuals: A longitudinal (REACTION) study were generated on the basis of age, sex and body mass index at baseline. The primary outcome was all-cause mortality. The secondary outcomes were a composite of new-onset major adverse cardiovascular events, hospitalization for heart failure, and renal dysfunction (eGFR < 60/min/1.73 m²).

Results

We identified 769 matched pairs of diabetic patients and control subjects. Serum ANGPTL8 levels were elevated in patients with diabetes compared to control subjects (618.82 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 318.08 vs 581.20 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 299.54 pg/mL, p = 0.03). Binary logistic regression analysis showed that elevated ANGPTL8 levels were associated with greater risk ratios (RRs) of death (RR in quartile 4 vs. quartile 1, 3.54; 95% CI 1.32–9.50) and renal dysfunction (RR in quartile 4 vs. quartile 1, 12.43; 95% CI 1.48–104.81) only in diabetic patients. Multivariable-adjusted restricted cubic spline analyses revealed a significant, linear relationship between ANGPTL8 and all-cause mortality in diabetic patients (p for nonlinear trend = 0.99, p for linear trend = 0.01) but not in control subjects (p for nonlinear trend = 0.26, p for linear trend = 0.80). According to ROC curve analysis, the inclusion of ANGPTL8 in QFrailty score significantly improved its predictive performance for mortality in patients with diabetes.

Conclusion

Serum ANGPTL8 levels were associated with an increased risk of all-cause mortality and could be used as a potential biomarker for the prediction of death in patients with diabetes.

Angiopoietin-like protein 8 accelerates atherosclerosis in ApoE-/- mice

BACKGROUND AND AIMS

Angiopoietin-like protein 8 (ANGPTL8) is a hormone involved in regulating lipid metabolism. Patients with coronary artery disease have markedly higher plasma levels of ANGPTL8 than controls; however, the role of ANGPTL8 in atherosclerosis has not been explored. Therefore, we explored the effects of ANGPTL8 on atherosclerosis development in a mouse model.

METHODS

We induced experimental atherosclerosis in ApoE^-/- mice ANGPTL8-knockdown. and ANGPTL8-overexpression ApoE^-/- mice. We also explored the mechanism using ANGPTL8-overexpression macrophages.

RESULTS

ANGPTL8 expression was increased in human and mouse atherosclerotic lesions. ANGPTL8 overexpression promoted the development of atherosclerosis whereas ANGPTL8 knockdown protected against atherosclerosis. Immunofluorescence co-staining results showed that ANGPTL8 was expressed in macrophages in atherosclerotic plaques. Compared with wild type cells, ANGPTL8-overexpressing macrophages, including bone marrow-derived macrophages and Raw 264.7 macrophages, showed enhanced foam cell formation and increased accumulation of cholesterol that was induced by increased uptake and decreased efflux of cholesterol. The results of this study also showed that ANGPTL8 induced the expression of CD36 and scavenger receptor (SR)-A, and inhibited the expression of SR-BI.

CONCLUSIONS

Our findings demonstrate an unanticipated role of ANGPTL8 in the development of atherosclerosis and regulation of foam cell formation. ANGPTL8 may be a promising new target for atherosclerosis.

Moderate-Intensity Exercise and Musical Co-Treatment Decreased the Circulating Level of Betatrophin

Introduction. In general, the significant contribution of lack of physical activity is strongly correlated with lipid metabolism and metabolic disorder. Hitherto, betatrophin is a potential hormone that regulates the lipid profile in the body circulation-associated triglyceride level. This study was designed to evaluate the alteration of betatrophin levels in subject-onset hypertriglyceridemia with exercise intervention co-treated with music. Materials and Methods. A total of 60 nonprofessional athletes were enrolled in this study and given moderate-intensity exercise (MIE) combined with middle rhythm musical co-treatment. The ELISA method was applied to quantify the serum level of betatrophin in all samples. The statistical analysis was performed by applying the Kolmogorov–Smirnov normality test, one-way ANOVA, and parametric linear correlation and regression. Results. Interestingly, our data show that MIE decreased the circulating level of betatrophin combined with music (12.47 ± 0.40 ng/mL) compared with that without musical co-treatment (20.81 ± 1.16 ng/mL) and high-intensity exercise (26.91 ± 2.23 ng/mL). The plasma level of betatrophin was positively correlated with triglycerides (r = 0.316, p≤0.05), systolic blood pressure (r = 0.428, p≤0.01), HDL (r = 0.366, p≤0.05), energy expenditure (r = 0.586, p≤0.001), PGC-1α (r = 0.573, p≤0.001), and irisin (r = 0.863, p≤0.001). By contrast, the plasma level of betatrophin was negatively associated with age (r = −0.298, p≤0.05) and LDL cholesterol (r = −0.372, p≤0.05). Importantly, betatrophin is a significant predictor for energy expenditure (p≤0.001) and plasma triglyceride levels (p≤0.05). Conclusions. Our data demonstrate that betatrophin levels decreased the post-MIE and musical therapeutical combination. Therefore, betatrophin may provide a benefit as the potential biomarker of physiological performance-associated physical training.

Association of ANGPTL8 (Betatrophin) Gene Variants with Components of Metabolic Syndrome in Arab Adults

Angiopoietin-like protein 8 (ANGPTL8) has a role in lipid metabolism, beta-cell proliferation and diabetes progression, however, the association between different variants in the ANGPTL8 gene and metabolic syndrome (MetS) components has not been studied widely especially in Arab ethnic groups. In this study, the associations of ANGPTL8 variants on MetS risk in Saudi Arab adults were investigated. A total of 905 unrelated Saudi adults (580 healthy controls and 325 MetS) were included. MetS was screened based on the International Diabetes Federation (IDF) criteria. The genotype and allele frequency distribution of rs737337 (T/C) and rs2278426 (C/T) polymorphism in ANGPTL8 gene was studied. Participants with MetS were significantly older, had higher BMI, and rs737337 polymorphism frequency was significantly lower than in control. Furthermore, the TC + CC genotype and C allele of rs737337 (T/C) was associated with decreased risk of hypercholesterolemia and hyperglycemia [odds ratio (OR) 0.61, 95%CI 0.40-0.93, p = 0.016 and OR 0.58, 0.39-0.86, p = 0.007 respectively for hypercholesterolemia; and OR 0.66, 0.45-0.97, p = 0.032 and OR 0.65, 0.46-0.93; p = 0.016 respectively for hyperglycemia]. Similarly, CT, CT + TT genotype and T allele of rs2278426 (C/T) were associated with decreased risk of hyperglycemia (p < 0.05). In conclusion, the study suggests that the gene variants in SNPs rs 737337 (T/C) and rs 2278426 (C/T) are associated with lower risk of hypercholesterolemia and hyperglycemia. These findings supplement the growing literature supporting the role of ANGPTL8 in lipid and glucose metabolism.

Evidences for Expression and Location of ANGPTL8 in Human Adipose Tissue

The metabolism of triglycerides (TGs) is regulated, among others, by the lipoprotein lipase (LPL) that hydrolyses the TGs on endothelial cells. In turn, LPL is inhibited by the ANGPTLs family of proteins, such as ANGPTL3, 4, and, 8; the latter is the least known. In this work, we have tried to establish the expression and localisation of the Angiopoietin-like 8 (ANGPTL8) protein in the visceral adipose tissue (VAT) of morbid-obese and non-obese patients. 109 subjects (66 women and 43 men) undergoing laparoscopic surgery participated in this study. A blood sample and a portion of the VAT were obtained, and the patients were classified according to their Body Mass Index (BMI) as non-obese (19.5–30 kg/m²) and morbid-obese (40–50 kg/m²). No significant changes in ANGPTL8 plasma levels were determined by EIA in obese patients. The immunocytochemistry and Western blotting showed the presence of increased ANGPTL8 in morbid-obese patients (p < 0.05). In-situ hybridisation and a real time polymerase chain reaction (RT-PCR) confirmed that the mRNA that encodes ANGPTL8 was present in adipocytes, without differences in their nutritional state (p = 0.89), and even in the endothelial cells. Our data suggests that ANGPT8 plasmatic levels do not change significantly in patients with morbid obesity, although there is a modest difference related to gender. Besides, we demonstrate that in visceral adipose tissue, ANGPTL8 is well defined in the cytoplasm of adipocytes coexisting with perilipin-1 and its mRNA, also is present in endothelial cells. These findings suggest the possibility that among other functions, ANGPTL8 could perform either a paracrine and/or an endocrine role in the adipose tissue.

Are adropin, apelin, elabela, asprosin and betatrophin biomarkers for chronic hepatitis and staging of fibrosis?

Chronic viral hepatitis affects nearly one half billion people; it can result in hepatic fibrosis and cirrhosis if untreated. We investigated whether the polypeptides, adropin, apelin, elabela, asprosin and betatrophin, could be useful biomarkers for diagnosing chronic hepatitis and for the staging fibrosis. Patients 18-60 years old who underwent a liver biopsy for chronic hepatitis B (CHB) or C (CHC) from January 2014 to January 2019 were included in our study. The patients were divided into three groups: control group, CHB group, and CHC group. The CHB group comprised four subgroups based on the severity of the hepatic fibrosis. Liver biopsy specimens of all groups were evaluated for adropin, apelin, elabela, asprosin and betatrophin immunoreactivity by light microscopy. Adropin, apelin, elabela and betatrophin were immunoreactive in the hepatocytes, while asprosin was not in any group. In the CHB group, adropin and elabela immunoreactivity was increased significantly in stages III and IV patients compared to the other subgroups, whereas stages I and II patients were comparable to the control group. The CHC group exhibited decreased betatrophin immunoreactivity and increased elabela immunoreactivity compared to the control group. We suggest that adropin and elabela can provide clues for staging and monitoring fibrosis in CHB, and may be potentially useful biomarkers.

ANGPTL8 Gene Polymorphism rs2278426 Is Related to Carotid Intima-Media Thickness in T2DM

AIM

ANGPTL8 is a cytokine expressed and secreted by liver and adipose tissue, and is involved in glucose, lipid, and energy metabolism. Although studies have shown that ANGPTL8 is elevated in type 2 diabetes mellitus (T2DM) and cardiovascular disease, few have examined the association between ANGPTL8 single-nucleotide polymorphisms and the risk of macrovascular complications in T2DM patients. This study aimed to explore the relationship between rs2278426 and carotid intima-media thickening (cIMT) in T2DM.

METHODS

A total of 217 T2DM patients and 201 healthy control subjects with normal glucose tolerance were recruited in the study. T2DM patients were divided into two groups: T2DM patients without cIM thickening (cIMT <1 mm, 109 cases) and T2DM patients with cIM thickening (cIMT ≥1 mm, 108 cases). rs2278426 genotypes in all 418 subjects were determined and the risk of T2DM and T2DM with cIM thickening analyzed.

RESULTS

CT+TT-genotype frequency in T2DM was higher than in controls with normal glucose tolerance, and the proportion of the CT+TT genotype in the group with cIMT was higher than in the group (P<0.05). In addition, T alleles were associated with waist:hip ratio, triglycerides, high density-lipoprotein cholesterol, plasma glucose at 2 hours' oral glucose tolerance, and homeostatic model assessment of insulin resistance (P<0.05).

CONCLUSION

Generally, carriers of the T allele at rs2278426 are more likely to develop T2DM, and the risk of cIM thickening is significantly increased for T-allele carriers with T2DM, which indicates an increased risk of macroangiopathy.

The ANGPTL8 rs2278426 (C/T) Polymorphism Is Associated with Prediabetes and Type 2 Diabetes in a Han Chinese Population in Hebei Province

BACKGROUND

Our aim was to investigate the association between the genetics of the angiopoietin protein-like 8 (ANGPTL8) rs2278426 (C/T) polymorphism with prediabetes (pre-DM) and type 2 diabetes (T2DM) in a Han Chinese population in Hebei Province, China.

METHODS

We enrolled 1,460 participants into this case-control study: healthy controls, n = 524; pre-DM, n = 460; and T2DM: n = 460. Ligase assays on blood samples from all participants were used to identify polymorphisms. Differences in genotype and allele distributions were compared by the chi-square test and one-way analysis of variance, and a post hoc pairwise analysis was performed using the Bonferroni test. The logistic regression technique was adjusted for age, sex, and body mass index.

RESULTS

The frequency of the TT (10.9%) genotype was significantly higher in pre-DM patients than in controls (odds ratio [OR] = 1.696, 95% confidence interval [CI] = 1.026-2.802, P=0.039). In the T2DM group, the CT (48%) and TT (15%) genotypes were significantly higher compared with those in the control group (CT : OR = 1.384, 95% CI = 1.013-1.890, P=0.041; TT : OR = 2.530, 95% CI = 1.476-4.334, P=0.001). The frequency of the T allele was significantly higher in the pre-DM (32.8%) and T2DM (39%) groups compared with the control group (26.9%) and was significantly associated with an increased risk of pre-DM (OR = 1.253, 95% CI = 1.017-1.544, P=0.034) and T2DM (OR = 1.518, 95% CI = 1.214-1.897, P=0.001). Furthermore, insulin levels in the pre-DM and T2DM groups were significantly decreased in those with the TT genotype compared with the CC and CT genotypes.

CONCLUSION

ANGPTL8 rs2278426 may be involved in the mechanism of insulin secretion and could lead to an increased risk of pre-DM and T2DM.

Regulation of angiopoietin-like protein 8 expression under different nutritional and metabolic status

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease with increasing prevalence worldwide. Angiopoietin-like protein 8 (ANGPTL8), a member of the angiopoietin-like protein family, is involved in glucose metabolism, lipid metabolism, and energy homeostasis and believed to be associated with T2DM. Expression levels of ANGPTL8 are often significantly altered in metabolic diseases, such as non-alcoholic fatty liver disease (NAFLD) and diabetes mellitus. Studies have shown that ANGPTL8, together with other members of this protein family, such as angiopoietin-like protein 3 (ANGPTL3) and angiopoietin-like protein 4 (ANGPTL4), regulates the activity of lipoprotein lipase (LPL), thereby participating in the regulation of triglyceride related lipoproteins (TRLs). In addition, members of the angiopoietin-like protein family are varyingly expressed among different tissues and respond differently under diverse nutritional and metabolic status. These findings may provide new options for the diagnosis and treatment of diabetes, metabolic syndromes and other diseases. In this review, the interaction between ANGPTL8 and ANGPTL3 or ANGPTL4, and the differential expression of ANGPTL8 responding to different nutritional and metabolic status during the regulation of LPL activity were reviewed.

Plasma Betatrophin Levels and Carotid Atherosclerosis

Aims

Betatrophin is a recently identified circulating adipokine that may affect lipid and glucose metabolism. However, the association between plasma betatrophin levels and carotid atherosclerosis has not been elucidated.

Methods

We investigated plasma betatrophin levels in 153 subjects undergoing carotid ultrasonography. The severity of plaque was evaluated as plaque score.

Results

Of the 153 subjects, plaque was found in 63 (41%). Plasma betatrophin levels were higher in 63 subjects with plaque than in 90 without plaque (median 906 vs. 729 pg/mL, P < 0.025). A stepwise increase in betatrophin levels was found depending on the plaque score: 729 pg/mL in score = 0 (n = 90), 802 pg/mL in score = 1 (n = 31), and 978 pg/mL in score ≥ 2 (n = 32) (P < 0.01). In particular, betatrophin levels in subjects with score ≥ 2 were higher than in those with score = 0 (P < 0.05). Moreover, betatrophin levels correlated with plaque score (r = 0.23, P < 0.01), but no significant correlation was found between betatrophin levels and triglyceride or HbA1c levels. The percentage of subjects with betatrophin > 800 pg/mL was higher in subjects with plaque than in those without plaque (65% vs. 44%) and was highest in score ≥ 2 (78%) (P < 0.005). In the multivariate analysis, betatrophin level was not a significant factor for the presence of plaque but was a significant factor for plaque score ≥ 2, independent of atherosclerotic risk factors. The odds ratio for score ≥ 2 was 4.9 (95% CI = 1.9-12.8) for betatrophin > 800 pg/mL.

Conclusions

Plasma betatrophin levels were found to be high in subjects with carotid plaque and to be associated with the severity of plaque. Betatrophin may play a role in the progression of carotid atherosclerosis.

The potential role of angiopoietin-like protein-8 in type 2 diabetes mellitus: a possibility for predictive diagnosis and targeted preventive measures?

BACKGROUND

Previous studies showed altered angiopoietin-like protein-8 (ANGPTL-8) circulating levels in type 2 diabetes mellitus (DM). Whether or not the alteration in ANGPTL-8 level can be a predictive maker for increased DM risk remains unclear.

AIM

Investigating possible role of ANGPTL-8 as a risk predictor of type2 DM, in addition to a set of factors likely to affect ANGPTL-8 level.

METHODS

One hundred recently diagnosed persons with type 2 DM and 100 sex- and age-matched healthy controls were enrolled. Exclusion criteria included type 1 DM, acute infections, history of chronic kidney disease, malignancy, and blood loss or transfusion. Serum levels of ANGPTL-8, blood pressure, weight, height, glycosylated hemoglobin (HbA1c), fasting blood glucose, cystatin C, lipid profile, liver, and kidney function tests were assessed. The independent relationship between DM and ANGPTL-8 was tested in the unadjusted and multiple-adjusted regression models.

RESULTS

Serum ANGPTL-8 levels showed significant elevation among persons with vs. without DM (p = 0.006), positive correlation with HbA1c (p < 0.001), and negative correlation with estimated GFR (eGFR) (p = 0.003) but no significant correlation to fasting glucose level. In the unadjusted model, patients in the third tertile of ANGPTL-8 had 4 times risk of DM (OR 4.03; 95% CI = 1.37-11.84). Data adjustment for cardiovascular diseases, smoking, body mass index, systolic blood pressure, alanine transaminase (ALT), and low-density lipoprotein (LDL) increased the direct relationship between ANGPTL-8 and DM (OR 6.26; 95% CI = 1.21-32.50). However, the risk significantly decreased after adjustment of Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) eGFR creatinine-cystatin (OR 2.17; 95% CI = 0.10-49.84).

CONCLUSION

This study highlights a possible predictive role of ANGPTL-8 in diabetic complications, particularly nephropathy. Larger prognostic studies are needed to validate the cause-effect relationship between ANGPTL-8 and deteriorated kidney functions.

Angptl8 mediates food-driven resetting of hepatic circadian clock in mice

Diurnal light-dark cycle resets the master clock, while timed food intake is another potent synchronizer of peripheral clocks in mammals. As the largest metabolic organ, the liver sensitively responds to the food signals and secretes hepatokines, leading to the robust regulation of metabolic and clock processes. However, it remains unknown which hepatokine mediates the food-driven resetting of the liver clock independent of the master clock. Here, we identify Angptl8 as a hepatokine that resets diurnal rhythms of hepatic clock and metabolic genes in mice. Mechanistically, the resetting function of Angptl8 is dependent on the signal relay of the membrane receptor PirB, phosphorylation of kinases and transcriptional factors, and consequently transient activation of the central clock gene Per1. Importantly, inhibition of Angptl8 signaling partially blocks food-entrained resetting of liver clock in mice. We have thus identified Angptl8 as a key regulator of the liver clock in response to food.

ANGPTL8 regulates adipocytes differentiation and adipogenesis in bovine

The formation of bovine adipose tissue involves complex developmental and physiological processes that play a vital role in determining the quality of beef; however, the regulatory mechanisms are largely unknown. Angiopoietin-like protein 8 (ANGPTL8) has been reported to be involved in the development of adipose tissue; however, the mechanism of adipogenesis which is regulated by ANGPTL8 has not been revealed in cattle. In this study, RT-qPCR and Oil Red O staining were performed to detect the expression of ANGPTL8 and adipocyte differentiation in bovine. We found that ANGPTL8 had a high expression level in adipose tissue and that the expression pattern was consistent with those of PPARγ, C/EBPα and LPL which are key regulators and transcription factors involved in preadipocyte differentiation and adipogenesis. The overexpression of ANGPTL8 by the adenovirus vector promoted lipid droplet formation in adipocytes. Thus, we speculated that ANGPTL8 could significantly enhance lipid deposition. Moreover, the expression of LPL and SREBP1, key genes inhibiting adipogenesis, was significantly decreased by ANGPTL8 overexpression. These results suggested that ANGPTL8 promotes adipocyte differentiation. In conclusion, we consider that ANGPTL8 regulates adipocyte differentiation and adipogenesis in bovine.

Angiopoietin-like 8 (ANGPTL8) expression is regulated by miR-143-3p in human hepatocytes

Angiopoietin-like protein 8 (ANGPTL8) is associated with reduced HDL-cholesterol levels and may contribute to the development of dyslipidemia. Factors regulating ANGPTL8 expression remain poorly understood. Here we analyzed the relationship between miRNA-143-3p and ANGPTL8 in liver cells. Using target prediction algorithms, we identified a putative binding site for miR-143-3p in the ANGPTL8 3' untranslated region (3'UTR). Exogenous miR-143-3p interacted with the ANGPTL8 3'UTR to downregulate its expression compared to scrambled sequence control. Transfection of HepG2 cells with miR-143-3p mimic or siRNA resulted in decreased or increased ANGPTL8 transcript and protein levels, respectively. Treatment of HepG2 cells with 30 mM glucose, 100 nM insulin, or 75 ng/ml lipopolysaccharide to mimic hyperglycemic, hyperinsulinemic, and proinflammatory conditions corresponded with increased miR-143-3p and ANGPTL8 levels. Inhibition of miR-143-3p amplified ANGPTL8 response to these treatments, suggesting that the miRNA acts to suppress ANGPTL8 expression under metabolically distorted conditions. These results, combined with growing evidence supporting a role for ANGPTL8 in the regulation of HDL-C metabolism, provide a better understanding of the molecular mechanisms underlying ANGPTL8 expression.

Betatrophin association with serum triglyceride levels in obstructive sleep apnea patients

BACKGROUND

Obstructive sleep apnea (OSA) is a common sleep problem, in which patients are at increased risk for metabolic and cardiovascular problems, including metabolic syndrome, diabetes mellitus (DM), and dyslipidemia. Betatrophin is a novel protein that regulates fatty acid and triglyceride (TG) metabolism and is related to obesity and metabolic abnormalities, including metabolic syndrome, DM, and dyslipidemia. Although OSA and betatrophin share common abnormalities, their relationship has not been investigated.

AIM

The aim of this study is to investigate the relationships among betatrophin, OSA, and the serum lipid profile.

METHODS

Ninety consecutive patients with suspected OSA underwent polysomnography (PSG) to confirm OSA. Plasma betatrophin, leptin, adiponectin, and the full lipid profile were analyzed. The patients were categorized as OSA or control based on the apnea-hypopnea index (AHI).

RESULTS

About 61% of patients had OSA, and 39% had normal PSG. The levels of betatrophin, leptin, and adiponectin were higher in patients with OSA (256.59 ± 29.35, 374.20 ± 37.93, and 17.86 ± 2.63 μg/mL, respectively) compared to the controls (141.86 ± 26.20, 205.53 ± 14.75, and 7.52 ± 1.02 μg/mL, respectively). Betatrophin levels were correlated with the AHI, leptin (r = 0.413, P = 0.002, r = 0.782, P = 0.000). TG levels were significantly higher, and high-density lipoprotein cholesterol (HDL-C) levels were lower, in OSA patients compared to controls (244 ± 20.33 vs. 138 ± 14.89, and 37.21 ± 1.26 vs. 43.78 ± 1.62, respectively). The TG level was correlated with betatrophin (r = 0.353, P = 0.013). Multiple regression analysis showed that the AHI, leptin, and arousals were independent predictors of betatrophin level (B = 1.70 P = 0.046 95%, B = 0.56 P < 0.005, and B = 1, 2, P = 0.003, respectively).

CONCLUSIONS

Our results suggest a complex relationship between OSA, betatrophin, TG, and HDL, as well as other adipokines. Our results require further investigation to assess this complex association and re-evaluate previous related studies.

Downregulated angiopoietin-like protein 8 production at calving related to changes in lipid metabolism in dairy cows

Acute physiological adaptation of lipid metabolism during the postpartum transition period of cows facilitates peripheral metabolic regulation. Hepatokines, which are hormones secreted from hepatocytes, are presumed to play a critical role in systemic metabolic regulation. Angiopoietin-like protein 8 (ANGPTL8) has been identified as a novel hepatokine associated with circulating triglyceride concentrations in mice and humans. However, regulation of ANGPTL8 and its physiological effects is still unknown in cattle. The present study aimed to reveal changes in ANGPTL8 expression and secretion during the periparturient period, and to investigate its regulatory effect on adipocytes and mammary epithelial cells. In the peripartum period, liver ANGPTL8 mRNA expression was lesser on the day of parturition and 1 wk postpartum than it was 1 wk before parturition (P < 0.05). Moreover, plasma ANGPTL8 concentrations decreased on the day of parturition as compared with that 1 wk before parturition (P < 0.05). In addition, ANGPTL8 expression in cultured bovine hepatocytes was downregulated after oleate and palmitate treatment but upregulated after insulin treatment (P < 0.05). ANGPTL8 decreased hormone-sensitive lipase (HSL) expression in differentiated adipocytes and cluster of differentiation 36 (CD36), fatty acid synthase (FAS), acetyl-coa carboxylase (ACC), and stearoyl-coa desaturase (SCD) in cultured bovine mammary epithelial cells (P < 0.05). These data suggest that hepatic ANGPTL8 production was downregulated postpartum when the cows experienced a negative energy balance. This downregulation was associated with increased concentrations of NEFA and decreased concentrations of insulin in lactating cows, and it facilitated lipid mobilization from adipose tissue to the mammary glands. We speculate that ANGPTL8 might have beneficial effects in reverting or improving the physiological adaptation and pathological processes of lipid metabolism during the peripartum period.

Associations Between Plasma Betatrophin Levels and Coronary and Peripheral Artery Disease

Aim: Betatrophin, a recently identified circulating adipokine, affects lipid and glucose metabolism. However, association between plasma betatrophin levels and atherosclerotic diseases, such as coronary artery disease (CAD) and peripheral artery disease (PAD), has not been elucidated.

Methods: We investigated plasma betatrophin levels in 457 patients undergoing elective coronary angiography who also had ankle-brachial index (ABI) test for PAD screening.

Results: Of the 457 study patients, CAD was present in 241 patients (53%) (1-vessel [1-VD], n = 99; 2-vessel [2-VD], n = 71; 3-vessel disease [3-VD], n = 71). Compared to 216 patients without CAD, 241 with CAD had higher betatrophin levels (median 1120 vs. 909 pg/mL, p < 0.001). A stepwise increase in betatrophin levels was found depending on the number of > 50% stenotic coronary vessels: 909 in CAD(-), 962 in 1-VD, 1097 in 2-VD, and 1393 pg/ml in 3-VD (p < 0.001). Betatrophin levels correlated with the number of > 25% stenotic segments (r = 0.24, p < 0.001). PAD (ABI < 0.9) was found in 41 patients (9%). Plasma betatrophin levels were also significantly higher in 41 patients with PAD than in 416 without PAD (1354 vs. 981 pg/mL, p < 0.001). In the multivariate analysis, betatrophin levels were not a factor for CAD, but they were a significant factor for 3-VD and PAD independent of atherosclerotic risk factors. The odds ratios for 3-VD and PAD were 1.06 (95%CI = 1.01–1.11) and 1.07 (95%CI = 1.01–1.13) for a 100-pg/mL increase in betatrophin levels, respectively (p < 0.05).

Conclusion: Plasma betatrophin levels were associated with the presence and severity of CAD and PAD, suggesting betatrophin has a role in atherosclerosis.

The negative effect of ANGPTL8 on HDL-mediated cholesterol efflux capacity

Background

It is well known that angiopoietin-like protein 8 (ANGPTL8) exerts its effects on lipid metabolism through the inhibition of lipoprotein lipase and subsequent elevation of plasma triglyceride. However, it is not clear whether ANGPTL8 could affect lipid metabolism via other pathways. The study was aimed to investigate the effects of ANGPTL8 on the function of high-density lipoprotein (HDL), which plays a protective role in atherosclerosis progression.

Methods

Two hundred and ten subjects were recruited. Plasma ANGPTL8 was measured by enzyme-linked immunosorbent assays. Cholesterol efflux capacity was chosen as the biomarker of HDL function and measured via H³-cholesterol loading THP-1 cell models.

Results

ANGPTL8 exhibited no significant difference between CAD group and nonCAD group, but ANGPTL8 in DM group was significantly higher than that in the nonDM group [568.3 (406.2–836.8) vs 458.2 (356.8–755.6), P = 0.023]. Compared to controls, subjects in CAD group and DM group exhibited significantly lower cholesterol efflux capacity [CAD: 14.58 ± 2.06 vs 12.51 ± 2.83%, P < 0.0001; DM: 13.62 ± 2.57 vs 12.34 ± 3.16%, P = 0.0099]. ANGPTL8 was inversely correlated with cholesterol efflux capacity (r = − 0.188, P < 0.01). Regression analysis revealed that plasma ANGPTL8 was an independent contributor to cholesterol efflux capacity (standardized β = − 0.143, P = 0.023).

Conclusion

ANGPTL8 presents a negative effect on HDL-mediated cholesterol efflux capacity.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0785-x) contains supplementary material, which is available to authorized users.

Association between rs2278426 (C/T) and rs892066 (C/G) variants of ANGPTL8 (betatrophin) and susceptibility to type2 diabetes mellitus

BACKGROUND

Angiopoietin-like protein 8 (ANGPTL8) is a hormone that mainly secreted from the liver and adipose tissue and plays an important role in the proliferation of pancreatic beta cells and lipid metabolism. Therefore, we studied the association of ANGPTL8 rs2278426 (C/T) and rs892066 (C/G) polymorphisms with the risk of type 2 diabetes mellitus (T2DM) and their association with biochemical parameters.

METHODS

Two hundred and eighty-eight subjects (controls; n = 138 and type 2 diabetic patients; n = 150) were enrolled in this study. Direct haplotyping was performed using amplification-refractory mutation system (ARMS)-RFLP-PCR.

RESULTS

The CT genotype frequency of rs2278426 (C/T) variant was significantly higher in T2DM patients compared to the controls group (P = 0.02), and there was a significant association between this genotype and increased risk of T2DM (OR: 2.41, CI: 1.26-4.59, P = 0.007). In addition, there was a significant relationship between CT genotype of this variant and high-density lipoprotein cholesterol (HDL-C), fasting blood sugar (FBS), insulin, insulin resistance and glycated hemoglobin (P < 0.05). Furthermore, bioinformatics analysis revealed that arginine (Arg) to tryptophan (Trp) substitution at rs2278426 position causes structural instability of ANGPTL8 protein. Genotype and allele distribution of rs892066 (C/G) was not statistically significant in T2DM patients compared to the control group. The distribution of haplotypes had no significant difference between controls and T2DM patients (P = 0.24).

CONCLUSION

Our results suggest that the rs2278426 (C/T) variant is associated with increased risk of T2DM and may cause dyslipidemia due to its effect on decreasing HDL-C levels.

Association of serum betatrophin with fibroblast growth factor-21 in women with polycystic ovary syndrome

PURPOSE

Betatrophin and fibroblast growth factor-21 (FGF-21), which are recently discovered members of hepatokine/adipokine family, have been proposed to be associated with some metabolic disorders in which insulin resistance plays a major role.

METHODS

We aimed to investigate serum betatrophin and FGF-21 concentrations in women with polycystic ovary syndrome (PCOS). In this cross-sectional study, we recruited 31 women with PCOS and 34 women as healthy controls. Serum betatrophin level and its relationship with serum FGF-21 level as well as metabolic parameters were examined.

RESULTS

Serum betatrophin level was significantly higher in women with PCOS‏ than the control group [1.10 (0.20-4.20) vs 0.70 (0.20-3.50) ng/ml, p = 0.004], whereas FGF-21 did not differ between the groups [74.80 (7.80-435.90) vs 119.30 (10.50-443.40) pg/ml, p = 0.13]. Serum betatrophin correlated positively with LH levels (r = 0.26, p = 0.03). After controlling BMI, there was a significant positive correlation between betatrophin and FGF-21 (r = 0.25, p = 0.04). Multivariate regression analysis revealed that FGF-21 and presence of PCOS were the significant predictors of betatrophin concentrations (R² = 0.22, F = 2.56, p = 0.03).

CONCLUSIONS

Our results indicate that betatrophin levels are increased and associated with LH and FGF-21 levels, but not with insulin resistance, in women with PCOS.

Association between circulating full-length angiopoietin-like protein 8 and non-high-density lipoprotein cholesterol levels in Chinese non-diabetic individuals: a cross-sectional study

Background

Angiopoietin-like protein 8 (ANGPTL8) is a novel hormone involved in the regulation of lipid metabolism and glucose homeostasis. There are inconsistent results regarding the association between ANGPTL8 and lipids in humans. We aimed to investigate the associations between ANGPTL8 and lipids in people without diabetes.

Methods

This was a cross-sectional study of 107 patients with dyslipidemia and 141 patients without. Dyslipidemia diagnosis was based on Chinese guidelines for the prevention and treatment of dyslipidemia in adults. Total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol (HDL-C) were examined. Non-HDL-C was calculated by subtracting HDL-C from TC. Circulating full-length ANGPTL8 concentrations were measured using enzyme-linked immunosorbent assay. Associations between log-transformed circulating full-length ANGPTL8 and serum lipids were examined using multivariate linear regression analysis.

Results

Circulating ANGPTL8 concentrations were significantly elevated in patients with dyslipidemia compared with patients without dyslipidemia. Circulating full-length ANGPTL8 concentrations were positively associated with non-HDL-C, TG and TC levels after adjusting for age, gender, body mass index, high-sensitivity C-reactive protein, alanine aminotransferase, and creatinine.

Conclusion

In people without diabetes, circulating full-length ANGPTL8 concentrations in patients with dyslipidemia were significantly elevated compared with non-dyslipidemia, and ANGPTL8 was positively associated with serum non-HDL-C levels.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0802-9) contains supplementary material, which is available to authorized users.

Apolipoprotein CIII may mediate the impacts of angiopoietin-like protein 8 on triglyceride metabolism

Background

Angiopoietin-like protein 8(ANGPTL8) and apolipoprotein CIII (apoCIII) were found to inhibit the activity of lipoprotein lipase (LPL) and disrupt the clearance of triglyceride-rich lipoproteins (TRLs), leading to hypertriglyceridemia. Whether any relationship exists between these two important modulators of triglyceride metabolism has not been reported. Besides, whether ANGPTL8 concentration is altered in the patients with coronary artery disease (CAD) is still unclear.

Methods

A hospital-based case-control study was conducted. Sixty-eight CAD subjects and fifty-two nonCAD controls were recruited. Plasma apoCIII, ANGPTL8 was measured.

Results

ANGPTL8 and apoCIII concentration exhibited no significant difference between CAD group and nonCAD group. Both ANGPTL8 and apoCIII were significantly correlated with triglyceride level(r = − 0.243, P = 0.008; r = 0.335, P < 0.001, respectively). Regression analysis revealed that apoCIII was an independent contributor to triglyceride level independent of ANGPTL8 concentration (standardized β = 0.230, P < 0.01).

Conclusion

ApoCIII may mediate the effects of ANGPTL8 on triglyceride metabolism.