Elevated circulating levels of betatrophin are associated with polycystic ovary syndrome

Association Between rs2278426 Polymorphism of the ANGPTL8 Gene and Polycystic Ovary Syndrome

Purpose

To study the relationship between the single nucleotide polymorphism (SNP) rs2278426 in the angiopoietin-like protein 8 gene (ANGPTL8) and polycystic ovary syndrome (PCOS).

Patients and methods

A total of 122 patients with PCOS and 108 controls were recruited for comparison of glucose, lipid, insulin, sex hormone, and ANGPTL8 levels. Polymerase chain reaction (PCR) and gene sequencing were performed for comparison of the frequency of the CC, CT, and TT rs2278426 genotypes and the rs2278426 allele distributions between the PCOS and control groups and between the obese and non-obese subgroups of the PCOS and control groups.

Results

The frequency of the T allele was significantly higher in the PCOS group than that in the controls (P = 0.037). In the dominant genetic model, the proportion of the CT+TT genotype in the PCOS group was significantly higher than that in the controls (P = 0.047). Subgroup analysis demonstrated that the T allele proportion was significantly higher in obese PCOS group than obese control group (P = 0.027). PCOS with the CT+TT genotype had significantly higher body mass index (BMI; P = 0.001), triglyceride (TG; P = 0.005), homeostasis model assessment of insulin resistance (HOMA-IR; P = 0.035), testosterone (P = 0.041), and ANGPTL8 (P = 0.037) levels and significantly lower high-density lipoprotein (HDL) levels (P = 0.025) than PCOS with the CC genotype. Obese PCOS group with the CT+TT genotype had significantly higher TG (P = 0.015), luteinizing hormone (LH; P = 0.030), fasting insulin (FINS; P = 0.039), HOMA-IR (P = 0.018), and ANGPTL8 (P = 0.049) levels than obese PCOS group with the CC genotype.

Conclusion

Polymorphisms of rs2278426 may induce glycolipid metabolic disorders by affecting ANGPTL8 levels and functions in Han Chinese females with obesity from the Shandong region, increasing the risk of PCOS in this population.

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.

ANGPTL8 in cardio-metabolic diseases

Dyslipidemia has been identified as an important factor in obesity, diabetes mellitus, and cardiovascular diseases (CVD), grouped as cardio-metabolic disorder diseases. Accordingly, dyslipidemia has become a major determinant in health worldwide. Both genome-wide association studies (GWAS) and research studies have focused on the elucidation of potential genetic mechanisms of dyslipidemia and the identification of new gene loci which contribute to the development of cardio-metabolic disorder diseases. Recent results indicate that both the ANGPTL8 gene and ANGPTL8 protein perform vital roles in modulating serum glucose and lipid metabolism. In this review, we examine the modulatory effects of ANGPTL8 and explore the potential mechanisms whereby ANGPTL8 affects serum glucose and lipid metabolism in cardio-metabolic disorder diseases.

New insights into ANGPTL8 in modulating the development of cardio-metabolic disorder diseases

Dyslipidemia is being identified as the most important factors of several health problems, such as obesity, diabetes mellitus, and cardiovascular diseases (CVD), which are always grouped together as cardio-metabolic disorder diseases. Consistently, dyslipidemia has become one of the most rising crisis of general health. Recently, it is worth noting that both genome-wide association studies (GWAS) and experimental research are being taken advantage to elucidate the potential genetic mechanisms of dyslipidemia and to identify new gene loci which contribute to the development of cardio-metabolic disorder diseases. According to the results, both ANGPTL8 gene and ANGPTL8 protein has been shown to embrace vital functions in modulating serum glucose and lipid metabolism. In the current review, the modulatory effects of ANGPTL8 in cardio-metabolic disorder diseases were summarized. In addition, novel insights which elucidate the potential mechanisms whereby ANGPTL8 affects glucose and lipid metabolism were also provided.

ANGPTL8 roles in proliferation, metabolic diseases, hypothyroidism, polycystic ovary syndrome, and signaling pathways

A new and atypical member of the ANGPTL family is angiopoietin-like protein 8 (ANGPTL8). This newly discovered hormone is a drug target that can be used to treat diabetes and dyslipidemia. The protein, as a hepatocyte-derived circulating factor, can control the triglyceride level of plasma. ANGPTL8 is significantly associated with inflammation and metabolic syndrome consequences such as obesity, diabetes, hypothyroidism, and PCOS. ANGPTL8 gene has four exons encoding a 22/5 kDa weight of 198 amino acid polypeptides. A highly preserved ANGPTL8 gene among mammals exhibits the essential hormone functions of ANGPTL8. Nevertheless, the physiological function of this hormone in the body is poorly understood. Studies published in PubMed (2008-2020), Google Scholar (2004-2020), and Scopus (2004-2020) databases of clinical trials were reviewed. This analysis is aimed at collecting information on ANGPTL8. The emphasis of this review was on gathering information about the role of ANGPTL8 in the metabolism of glucose and lipids and cell proliferation. It addition to the different roles of ANGPTL8 in diabetes and lipid metabolism, this review emphasized on the protein role in signaling pathways. The study also proposes the signaling pathways that may be considered as a new target for treatment.

The role of serum β-trophin and endostatin in patients with polycystic ovary syndrome: Are they correlated?

Background

It’s necessary to investigate the serum β-trophin and endostatin (ES) level and its influencing factors in patients with newly diagnosed polycystic ovary syndrome (PCOS).

Methods

Newly diagnosed PCOS patients treated in our hospital were selected, and healthy women who took physical examination during the same period as healthy controls. We detected and compared the related serum indicators between two groups, Pearson correlation were conducted to identify the factors associated with β-trophin and ES, and the influencing factors of β-trophin and ES were analyzed by logistic regression.

Results

A total of 62 PCOS patients and 65 healthy controls were included. The BMI, WHI, LH, FSH, TT, FAI, FBG, FINS, HOMA-IR, TC, TG, LDL, ES in PCOS patients were significantly higher than that of healthy controls, while the SHBG and HDL in PCOS patients were significantly lower than that of healthy controls (all p < 0.05). β-trophin was closely associated with BMI (r = 0.427), WHR (r = 0.504), FBG (r = 0.385), TG (r = 0.405) and LDL (r = 0.302, all p < 0.05), and ES was closely associated with BMI (r = 0.358), WHR (r = 0.421), FBG (r = 0.343), TC (r = 0.319), TG (r = 0.404, all p < 0.05). TG, BMI, WHR and FBG were the main factors affecting the serum β-trophin levels (all p < 0.05). FBG, TC and BMI were the main factors affecting the serum ES levels (all p < 0.05). The TG, β-trophin, ES level in PCOS patients with insulin resistance (IR) were significantly higher than that of those without IR (all p < 0.05).

Conclusion

Increased β-trophin is closely associated with increased ES in patients with PCOS, which may be the useful indicators for the management of PCOS.

Elevated Circulating Levels of Carnal ENST00000550337.1 Are Associated with Polycystic Ovary Syndrome in Chinese Women

OBJECTIVES

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disease. Some studies reported that the development of PCOS may be closely related to insulin resistance (IR). Interestingly, the long noncoding RNA (lncRNA) ENST00000550337.1 in peripheral blood is mainly involved in glucose metabolism. Therefore, the purpose of our study was to explore the relationship between lncRNA ENST00000550337.1 level and PCOS patients.

MATERIALS AND METHODS

Seventy-five PCOS patients and 72 healthy controls were enrolled in this study. We used qRT-PCR to detect the expression level of lncRNA ENST00000550337.1 in peripheral blood leukocytes from patients with PCOS. We also investigated potential relationships between lncRNA ENST00000550337.1 and the endocrine parameters in PCOS.

RESULTS

We observed that the expression of lncRNA ENST00000550337.1 in PCOS patients was significantly higher than that in the control subjects and positively correlated with PCOS occurrence, waist circumference, waist-hip ratio, IR, fasting insulin levels, and blood glucose. The expression of lnc RNA ENST00000550337.1 was positively correlated with PCOS (p = 0.003). There were independent correlations between IR and expression of lncRNA ENST00000550337.1 in patients with PCOS. Patients with elevated lncRNA ENST00000550337.1 expression had significantly increased PCOS risk after adjusting for age and BMI. LncRNA ENST00000550337.1 expression level provided a sensitivity of 81.3% and a specificity of 78.1% with a threshold value of 6.4648 for the prediction of PCOS. The area under the ROC was 0.813.

LIMITATIONS

There are some limitations to this study. First, the sample size was limited and the causal relationship between lncRNA ENST00000550337.1 and PCOS was not investigated due to the cross-sectional study design. Second, HOMA-IR does not fully accurately reflect the IR of patients.

CONCLUSIONS

The present study indicated that lnc RNA ENST00000550337.1 was related to PCOS occurrence, and elevated levels may be a risk factor for PCOS women. In addition, lncRNA ENST00000550337.1 might promote PCOS development partially by increasing IR and can be used as a potential molecular marker in patients with PCOS.

Evaluation of angiopoietin-like protein 3 (ANGPTL3) levels in polycystic ovary syndrome

AIM

Angiopoietin-like protein 3 (ANGPTL3) is recognized as a regulator of lipid metabolism. However, little is known about its association with insulin resistance in polycystic ovary syndrome (PCOS) setting. The present study aimed to investigate the serum levels of ANGPTL3 and adiponectin in PCOS women compared to healthy controls.

MAIN METHOD

In this study, a total of 175 premenopausal women (117 PCOS and 58 non-PCOS) were enrolled. Serum concentrations of ANGPTL3, adiponectin, fasting insulin, and other hormonal variables were measured using ELISA technique.

KEY FINDINGS

Results showed that adiponectin levels were significantly lower in PCOS group than those of non-PCOS group. However, serum levels of ANGPTL3, high-sensitivity C-reactive protein (hs-CRP), and homocysteine (Hcy) were found to be higher in PCOS patients, when compared to non-PCOS ones. Moreover, serum ANGPTL3 positively correlated with BMI and serum triglyceride, while it inversely correlated with serum HDL-C in PCOS patients.

SIGNIFICANCE

Our results demonstrated that increased levels of ANGPTL3 correlated with insulin resistance and dyslipidemia in PCOS patients, highlighting the need for future studies targeting its role in the pathogenesis of this disease.

Effect of preeclampsia and preeclampsia severity on insulin, HOMA-IR, and betatrophin levels in non-diabetic pregnant women

BACKGROUND

The aim of the study was to evaluate the effect of preeclampsia and its severity on insulin, the homeostatic model assessment of insulin resistance (HOMA-IR), and betatrophin levels in non-diabetic pregnant women.

METHODS

Our study comprised 102 pregnant women who were divided into the following three groups: (1) control, (2) severe preeclampsia, and (3) mild preeclampsia. The women were screened with the single-stage 75-g oral glucose tolerance test (OGTT), and the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria were used for diagnosis. Those women with type 2 diabetes (T2D) mellitus or gestational diabetes mellitus (GDM) were excluded from the study.

RESULTS

Maternal demographic characteristics were similar among the groups. Fasting plasma glucose and postprandial 2-h plasma glucose levels were significantly increased in the severe-preeclampsia group compared to that in the other groups. Fasting insulin levels were 14.3 ± 8.7uU/mL in the severe-preeclampsia group, 19.1 ± 6.0uU/mL in the mild-preeclampsia group, and 20.5 ± 12.5uU/mL in the control group and significantly lower in the severe-preeclampsia group than in the mild-preeclampsia and control groups. The serum betatrophin level was 7.8 ± 2.6 ng/mL in the severe-preeclampsia group, 6.1 ± 1.8 ng/mL in the mild-preeclampsia group, and 5.8 ± 1.3 ng/mL in the control group and significantly increased in the severe-preeclampsia group compared to other groups. HOMA-IR was similar among the groups. Maternal serum insulin levels were negatively (r = -0,255; P = 0.010) and serum betatrophin levels were positively (r = 0.368; P ≤ 0.001) correlated with preeclampsia severity.

CONCLUSION

Our results indicated that severe preeclampsia effect maternal serum glucose, insulin and betatrophin levels. Histhopatholical and immunohistochemical demostrations on pancreatic cells in new preeclampsia rat models will expand the information on the current situation.

Serum betatrophin levels are significantly increased in obese patients compared to lean patients regardless to the presence of PCOS

Betatrophin, which regulates glucose metabolism, is primarily expressed in liver and fat tissue. We aimed to investigate betatrophin levels in patients with polycystic ovary syndrome (PCOS) that is the most common endocrine pathology in women of reproductive age. A total of 69 women were included in this prospective study: 35 patients with PCOS (18 obese and 17 lean) and 34 healthy controls (17 obese and 17 lean). Patients who met the criteria were compared regarding betatrophin levels and other hormonal values. Serum betatrophin level did not differ between obese PCOS patients and obese controls, and lean PCOS patients and lean controls; while significantly increased in obese PCOS patients and controls compared to lean PCOS patients and controls. Total testosterone and androstenedione were significantly higher in patients with PCOS than in controls both in the obese and lean groups, while sex hormone-binding globulin was significantly lower in patients with PCOS than in controls both in the obese and lean groups. However, remaining hormone values were similar between groups. Betatrophin level was significantly increased in obese patients compared to lean patients independent to the presence of PCOS.

Anti proliferative and apoptotic effects on pancreatic cancer cell lines indicate new roles for ANGPTL8 (Betatrophin)

Despite considerable advances, the treatment of pancreatic cancer (PC) still requires much effort. Unusual regulation of the Wnt and apoptotic signaling pathways is widespread in cancer incidence. For instance, the WIF1 (Wnt inhibitory factor 1) gene is down-regulated in many cancers. The purpose of this study was to determine the effects of recombinant Betatrophin, a recently discovered hormone, on MiaPaca-II and Panc-1 pancreatic cell lines. Various concentrations of Betatrophin were added to MiaPaca-II and Panc-1 pancreatic cell lines during periods of 24 , 48, and 72 h. The MTT assay was applied to investigate cell proliferation after treatment. The rate of apoptotic cells was assessed using double-staining flow cytometry, and the expression levels of the WIF1 gene and Bcl2 protein was observed by real-time PCR and western blotting, respectively. The findings of this study suggest that Betatrophin has an anti-proliferative effect on both MiaPaca-II and Panc-1 cell lines, in line with the up-regulation of WIF1 as a tumor suppressor gene. Moreover, the induction of apoptosis by ANGPTL8 occurred by the down-regulation of Bcl2. Thus, Betatrophin can be proposed as a potential therapeutic drug for treating pancreatic cancer.

The Impact of Psoriasis and Metabolic Syndrome on the Systemic Inflammation and Oxidative Damage to Nucleic Acids

BACKGROUND

Psoriasis is a chronic systemic inflammatory disease associated with a wide range of comorbidities, including metabolic syndrome (MetS). Serum calprotectin, ANGPTL8, and oxidative damage to nucleic acids might be associated with both diseases. The presented study describes the influence of psoriasis and MetS on the serum levels of markers of systemic inflammation (calprotectin and ANGPTL8) and markers of oxidative damage to nucleic acids. The applicability of serum levels of calprotectin and ANGPTL8 for monitoring of the activity of psoriasis (diagnostic markers) is also evaluated.

METHODS

Clinical examination (PASI score, MetS), enzyme-linked immunosorbent assay (ELISA), and Enzyme Immunoassay (EIA). Serum calprotectin, ANGPTL8, 8-hydroxy-2'-deoxyguanosine, 8-hydroxyguanosine, and 8-hydroxyguanine. Results and Conclusions. The psoriasis significantly increased the serum level of calprotectin and the serum level of oxidative damage to nucleic acids, however not the serum level of ANGPTL8. The presence of MetS did not significantly affect the serum levels of calprotectin, ANGPTL8, and oxidative damage to nucleic acids in either psoriasis patients or controls. It seems that the serum level of calprotectin (but not the serum level of ANGPTL8) could be used as a biomarker for monitoring the activity of psoriasis.

Serum Fetuin-A levels are increased and associated with insulin resistance in women with polycystic ovary syndrome

BACKGROUND

Insulin resistance (IR) is a common characteristic of women with polycystic ovary syndrome (PCOS). It has been reported that circulating Fetuin-A levels were associated with IR and type 2 diabetes mellitus (T2DM). However, previous reports were inconsistent.

METHODS

Two hundred seven subjects were screened for PCOS according to the diagnostic guideline of the Rotterdam consensus criterion. Serum Fetuin-A levels were measured using an ELISA kit. An independent t-test or Nonparametric test was used to detect differences between PCOS and control groups. Spearman's correlation analysis was used to examine the association of the serum Fetuin-A with other parameters.

RESULTS

Our findings showed that circulating Fetuin-A concentration ranged from 196.6 to 418.2 μg/L for most women without PCOS (95%). Women with PCOS had higher circulating Fetuin-A levels than healthy women (437.9 ± 119.3 vs. 313.8 ± 60.5 μg/L; p <  0.01). Serum Fetuin-A was positively correlated with BMI, WHR, TG, TC, LDL-C, HOMA-IR, LH, T, and DHEA-S. Multivariate regression analysis showed that WHR, TG, HOMA-IR, and DHEA-S were independent predictors of the levels of circulating Fetuin-A. Binary logistic regression revealed that serum Fetuin-A was associated with the occurrence of PCOS. In addition, our ROC curve analysis found that the cutoff values for Fetuin-A to predict PCOS and IR were 366.3 and 412.6 μg/L.

CONCLUSION

Blood Fetuin-A may be a useful biomarker for screening women for PCOS and IR.

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.

Adipose Insulin Resistance and Circulating Betatrophin Levels in Women with PCOS

The role of IR and metabolic disorders has become a crucial topic of study in the pathogenesis of PCOS. Adipose tissue is an important target organ of insulin, and adipose IR plays an important role in the occurrence and development of PCOS. This study seeks to investigate the role of adipose IR in the development of PCOS and to examine its relationship with circulating betatrophin levels in women with PCOS. A cross-sectional analysis of a cohort of women with PCOS and healthy women was performed in this study. Serum betatrophin concentrations were measured by ELISA. Adipose IR was calculated using the product of fasting insulin and FFA concentrations, and the relationship between adipose IR, circulating betatrophin, and other parameters was analyzed. Adipose IR in women with PCOS was significantly higher than that in controls. We found that women with PCOS who have adipose IR (adipose IR ≥ 55) have a higher BMI and higher blood glucose, insulin, PRL, FFA, TG, HOMA-_IR, AUC_glucose, AUC_insulin, VAI_female, and BAI levels than PCOS-afflicted women without adipose IR, while M-values, and SHBG and LH levels were lower. In women with PCOS, serum betatrophin levels were significantly increased compared with controls. Adipose IR negatively correlated with M values and positively with circulating betatrophin levels in the study population. After metformin treatment, circulating betatrophin levels and adipose IR in women with PCOS were significantly decreased compared with pretreatment. Adipose IR is associated with betatrophin levels in women with PCOS. The combination of adipose IR and circulating betatrophin measurements may be significant for screening patients with PCOS.

Exercise and Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a complex endocrinopathy affecting both the metabolism and reproductive system of women of reproductive age. Prevalence ranges from 6.1-19.9% depending on the criteria used to give a diagnosis. PCOS accounts for approximately 80% of women with anovulatory infer-tility, and causes disruption at various stages of the reproductive axis. Evidence suggests lifestyle modification should be the first line of therapy for women with PCOS. Several studies have examined the impact of exercise interventions on reproductive function, with results indicating improvements in menstrual and/or ovulation frequency following exercise. Enhanced insulin sensitivity underpins the mechanisms of how exercise restores reproductive function. Women with PCOS typically have a cluster of metabolic abnormalities that are risk factors for CVD. There is irrefutable evidence that exercise mitigates CVD risk factors in women with PCOS. The mechanism by which exercise improves many CVD risk factors is again associated with improved insulin sensitivity and decreased hyperinsulinemia. In addition to cardiometabolic and reproductive complications, PCOS has been associated with an increased prevalence of mental health disorders. Exercise improves psychological well-being in women with PCOS, dependent on certain physiological factors. An optimal dose-response relationship to exercise in PCOS may not be feasible because of the highly individualised characteristics of the disorder. Guidelines for PCOS suggest at least 150 min of physical activity per week. Evidence confirms that this should form the basis of any clinician or healthcare professional prescription.

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.

Several Circulating Biomarkers for PCOS Diagnosis

AIMS

Irisin, Betatrophin and Zinc-α2-glycoprotein (ZAG) have been shown to be associated with insulin resistance (IR) and polycystic ovary syndrome (PCOS), respectively. The purpose of this study is to explore the potential accuracy of this combination of three cytokines in screening PCOS.

METHODS

186 individuals were recruited for this study. Circulating Irisin, Betatrophin and ZAG concentrations were measured by enzyme-linked immunosorbent assay. The association between these serum biomarkers and PCOS was assessed by logistic regression analysis. Receiver operating curve (ROC) analysis was performed to evaluate the diagnostic value of these biomarkers for PCOS women.

RESULTS

In women with PCOS, serum Irisin and Betatrophin levels were markedly elevated compared to those in healthy controls (p<0.01), while ZAG levels were lower (p<0.01). PCOS women with IR (M-value<6.28) had lower circulating ZAG concentrations, and higher circulating Irisin and Betatrophin levels relative to PCOS women without IR (M-value ≥ 6.28). ROC curve analyses showed that the AUC for Irisin, ZAG and Betatrophin for predicting PCOS were 0.77, 0.83 and 0.85, respectively. In a joint ROC curves analysis of these serum markers and other parameters, the results showed that the AUC was 0.93, and the sensitivity and specificity were 82.1 % and 92.3 %, respectively.

CONCLUSIONS

When compared to using single cytokine, the analysis of Irisin, ZAG and Betatrophin elevates the accuracy in diagnosing PCOS.

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.

Serum betatrophin levels are reduced in patients with full-blown polycystic ovary syndrome

Betatrophin is defined as a new marker in glucose homeostasis and lipid metabolism. We aimed to investigate the role of serum betatrophin in full-blown polycystic ovary syndrome (PCOS) patients and 47-aged healthy women, 51 full-blown PCOS patients were included in this cross-sectional study. Betatrophin concentrations were significantly lower in PCOS group and displayed a positive correlation only with serum tryglyceride in control group (p < .05). A cutoff level (464.5 ng/L) was determined for betatrophin according to Receiver Operating Characteristic curve. Using this value, 64.7% of PCOS patients were classified as below the cutoff and in this group betatrophin was found to correlate negatively with fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance (p = .038, p = .020, and p = .014, respectively), and positively with total testosterone (p = .041). In the rest of PCOS cases (35.3%) who had betatrophin higher than cutoff, positive correlation was found with low-density lipoprotein cholesterol (p = .009). In conclusion, betatrophin levels are reduced in full-blown PCOS patients who had worse metabolic phenotype.

Circulating Angiopoietin-like 8 protein (ANGPTL8/Betatrophin) in patients with polycystic ovary syndrome: a systematic review and multi effect size meta-analysis

The association between circulating betatrophin levels and polycystic ovary syndrome (PCOS) is controversial and the studies in the literature are inconsistent. The aim of our study was to systematically review and meta-analyze all available literature comparing circulating betatrophin levels between human PCOS patients and controls. Relevant studies were retrieved by online database and manual searching. A total of 11 studies were included in this meta-analysis. The standardized mean differences (SMDs) with 95% confidence intervals (CIs) were obtained by a random-effects meta-analysis. Meta-analysis of correlations was performed for the associations of betatrophin with anthropometric, lipid and hormonal covariates in PCOS patients. The results indicated that the betatrophin levels were significantly elevated in PCOS patients as compared to non-PCOS controls (SMD = 0.73, 95% CI = 0.22-1.24, Z = 2.83, p = .005). A one-study leave-out sensitivity analysis indicated that no single study had a significant influence on the overall outcome, suggesting the robustness of this meta-analysis. Our sub-group analysis indicated that this increase in betatrophin concentrations was regardless of normo-weight or obese body mass index (BMI) and insulin resistance might have an important role. There were significant positive correlations of betatrophin with age, free androgen index and free-testosterone in PCOS patients. In summary, regardless of BMI, the circulatory betatrophin levels are elevated in PCOS patients compared to controls. PCOS patients with higher insulin resistance had substantially higher circulating betatrophin concentrations.

The association between circulating irisin levels and different phenotypes of polycystic ovary syndrome

PURPOSE

The diagnosis of polycystic ovary syndrome (PCOS) is based on a combination of various clinical phenotypes in each patient. However, insulin resistance (IR) and dysmetabolism are not included in the diagnostic criteria of PCOS. Therefore, the definition of PCOS is controversial. The objective of this study is to investigate whether some PCOS phenotypes can be predicted by a circulating biomarker related to IR and metabolic dysfunction in PCOS women.

METHODS

One hundred and seventeen women with PCOS and 95 healthy women were recruited for this study. All individuals were assessed by the phenotypic and metabolic characteristics related to PCOS. A euglycemic-hyperinsulinemic clamp was performed to assess insulin sensitivity. Circulating irisin concentrations were determined with ELISA.

RESULTS

In our PCOS cohort, 65.8% of individuals were found to have hyperandrogenism. 83.8% had chronic oligoanovulation, and 80.3% of subjects showed polycystic ovaries. According to the diagnostic criteria of PCOS, 30.8% of PCOS subjects were diagnosed with the classic phenotype. In addition, 65.8% of PCOS women had insulin resistance. Serum irisin levels were significantly higher in PCOS women compared with healthy women. However, PCOS women with a normoandrogenic phenotype had similar circulating irisin levels as healthy women. PCOS women with the normoandrogenic phenotype had a low homeostasis model assessment of insulin resistance (HOMA-IR) and higher M-values than PCOS women with other phenotypes. Circulating irisin levels were associated with hyperandrogenism, but not with oligoanovulation or PCO morphology.

CONCLUSIONS

Circulating irisin may allow physicians to establish which women merit screening by a biomarker for PCOS.

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.

Investigation of Blood Betatrophin Levels in Obese Children with Non-Alcoholic Fatty Liver Disease

PURPOSE

The prevalence of obesity has significantly increased among children and adolescents worldwide and is becoming an important health care problem in parallel with the increased prevalence of obesity pediatric non-alcoholic fatty liver disease. Betatrophin is a newly define hormone that is commonly secreted by liver and plays role in glucose tolerance. This study aimed to investigate the relationship between serum betatrophin levels and non-alcoholic fatty liver disease in obese children.

METHODS

The study included 40 obese children with a body mass index (BMI) above 95th centile, and 35 non-obese subjects with a BMI 3-85th centile, whose age and gender were similar to those of the patient group. For the evaluation of metabolic parameters fasting serum glucose, insulin, alanine aminotransferase, aspartate aminotransferase, lipid profile and serum betatrophin levels were measured. Total cholesterol: high-density lipoprotein cholesterol and low-density lipoprotein cholesterol: high-density lipoprotein cholesterol ratios were calculated as "atherogenic indices."

RESULTS

Serum betatrophin levels of the obese subjects were similar to that of non-obese subjects (p=0.90). Betatrophin levels were not correlated with the metabolic parameters.

CONCLUSION

In the present study, levels of betatrophin are not different between obese and insulin resistant children and non-obese subjects, and they are not correlated with atherogenic indices. To elucidate the exact role of betatrophin in obesity, further studies are required to identify the betatrophin receptor and/or other possible cofactors.

ANGPTL8: An Important Regulator in Metabolic Disorders

Long-term controversy regarding the role of angiopoietin-like protein 8 (ANGPTL8) in beta-cell proliferation and diabetes progression made it a research spotlight. Recently, the controversy was resolved. Although ANGPTL8 could not control beta-cell expansion and islet function, ANGPTL8 was still considered as a novel but atypical member in the ANGPTL family because of its unique structure and crucial effects on lipid metabolism. Besides, ANGPTL8 also participated in some other disorders such as non-alcoholic fatty liver disease and renal dysfunction. Understanding the features of ANGPTL8 may offer new diagnostic and therapeutic approaches to metabolic-related diseases. Therefore, we reviewed most recent findings about ANGPTL8 and aimed to provide an integrated picture of ANGPTL8.

Angiopoietin-like protein 8: An attractive biomarker for the evaluation of subjects with insulin resistance and related disorders

Insulin resistance is prevalent worldwide and is associated with many metabolic diseases, in particular, type 2 diabetes mellitus (T2DM), obesity, nonalcoholic fatty liver disease (NAFLD), polycystic ovary syndrome (PCOS) and metabolic syndrome (MetS). Angiopoietin-like protein 8 (ANGPTL8), a newly-identified secreted protein composing of 198 amino acids, is enriched in the liver of human. Considering its promising potential for β-cell proliferation and therapeutic prospect for diabetes, ANGPTL8 has aroused extensive interests. However, a recent collaborative study confirmed that ANGPTL8 didn't stimulate dramatic β-cell regeneration. At present, a controversial scientific discussion on whether and how ANGPTL8 regulate insulin resistance has been ongoing. Interestingly, several in vitro and in vivo studies have suggested the complex roles of ANGPTL8 in insulin resistance. Data resulting from cross-sectional and longitudinal researches in human individuals involving the influence of ANGPTL8 on the development of insulin resistance were controversial. We therefore summarize currently clinical literature to exploit whether this exciting hormone could be applied for clinical application asa potential clinical biomarker to predict insulin resistance and related disorders.

ANGPTL8 (betatrophin) role in diabetes and metabolic diseases

Diabetes is a major disease worldwide that is reaching epidemic levels. Its increased prevalence as well as its association with a high number of complications such as cardiovascular diseases, nephropathy, and retinopathy makes it an important disease for investigation. ANGPTL8 is a recently identified hormone that has been associated with two functionally important processes in the development of type 2 diabetes, insulin resistance as well as lipid metabolism. Initial work has shown that ANGPTL8 was expressed in liver, white adipose, and brown adipose tissues. ANGPTL8 regulates the activity of lipoprotein lipase, which is a key enzyme in lipoprotein lipolysis pathway through its direct interaction with ANGPTL3. It has been also reported that it regulates the replication of β-cells in response to insulin resistance. As a result, many recent studies have focused on the association of ANGPTL8 with diabetes and obesity as well as its association with various metabolic markers in order to better understand its physiological role in glucose homeostasis and lipid metabolism. In this review, we will highlight some of the key clinical findings, mainly from human studies, that investigated the role of ANGPTL8 in metabolic diseases such as diabetes, obesity, and the metabolic syndrome.

Circulating betatrophin is associated with insulin resistance in humans: cross-sectional and interventional studies in vivo and in vitro

Betatrophin has a closely relationship with metabolism. However, its effect on metabolism disorder remains unclear. This study was comprised of a series of cross-sectional and interventional studies in vivo and vitro. PCOS women with IR and healthy women were recruited from the general population and outpatients. Plasma betatrophin levels were measured with ELISA. Insulin sensitivity was assessed with EHC. Gene expressions at mRNA and protein levels were determined with RT-PCR and Western blotting. Influences of insulin, metformin, rosiglitazone and over- or knockdown-expression of betatrophin were analyzed ex vivo. Our results indicated that IR women had higher betatrophin levels compared with the controls. Circulating betatrophin was positively correlated with BMI, WHR, Fat%, triglyceride, total cholesterol, LDL-C, AUC_glucose and AUC_insulin, luteinizing Hormone, FAI and HOMA-IR but negatively with M-value. Metformin treatment in PCOS women with IR led to a reduction of betatrophin levels. Insulin stimulation in hepatocytes increased betatrophin expression. Metformin or rosiglitazone led to a reduction of betatrophin expression in insulin-stimulated hepatocytes. In hepatocytes/macrophages co-culture systems, betatrophin expression was significantly increased, whereas this increase was eliminated by rosiglitazone. In hepatocytes, overexpression and knockdown of betatrophin decreased or increased insulin-stimulated insulin receptor, protein kinase B and insulin receptor substrate-1 phosphorylation respectively. Serum from metformin-treated women with IR decreased betatrophin expression and reinforced insulin signals. Thus, the present study provides the in vivo and in vitro evidence, suggesting that there is a cell cross-talking between hepatocytes with macrophages for the regulating betatrophin and it may be a useful marker for IR and metabolic disorders.

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

Betatrophin is a newly identified circulating adipokine playing a role in the regulation of glucose homeostasis and lipid metabolism. But its role in metabolic syndrome (MetS) remains unknown. Therefore, we aimed to compare the circulating betatrophin concentrations between patients with MetS and healthy controls. We recruited 47 patients with MetS and 47 age and sex matched healthy controls. Anthropometric and biochemical measurements were performed, and serum betatrophin levels were detected by ELISA. Full-length betatrophin levels in patients with MetS were significantly higher than those in controls (694.84 365.51 pg/ml versus 356.64 287.92 pg/ml; P <0.001). While no significant difference of total betatrophin levels was found between the two groups (1.20 0.79 ng/ml versus 1.31 1.08 ng/ml; P = 0.524). Full-length betatrophin level was positively correlated with fasting plasma glucose (FPG) (r = 0.357, P = 0.014) and 2-hour plasma glucose (2hPG) (r = 0.38, P <0.01). Binary logistic regression models indicated that subjects in the tertile of the highest full-length betatrophin level experienced higher odds of having MetS (OR, 8.6; 95% CI 2.8-26.8; P <0.001). Our study showed that full-length betatrophin concentrations were increased in drug-naïve MetS patients.

Follicular fluid cerebellin and betatrophin regulate the metabolic functions of growing follicles in polycystic ovary syndrome

Objective

The aim of this study was to assess the changes of follicular fluid (FF) and serum levels of cerebellin precursor protein 1 (cbln1) and betatrophin in patients with polycystic ovary syndrome (PCOS) undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) with a gonadotropin-releasing hormone (GnRH) antagonist protocol.

Methods

Twenty infertile women with PCOS and 20 control women diagnosed as poor responders undergoing ovarian stimulation with a GnRH antagonist were included. Blood samples were obtained during ovum pick-up. Follicular fluid from a dominant follicle was collected from the subjects. Using enzyme-linked immunosorbent assays, FF and serum levels of cbln1 and betatrophin were measured in both groups of participants. Metabolic and hormonal parameters were also determined and correlated with each other.

Results

Both groups of women had similar serum and FF betatrophin levels (55.0±8.9 ng/mL vs. 53.1±10.3 ng/mL, p=0.11). The serum and FF betatrophin levels of poor responders were found to be similar (49.9±5.9 ng/mL vs. 48.9±10.7 ng/mL, p=0.22). Conversely, the FF cbln1 levels of PCOS women were found to be significantly higher than the serum cbln1 levels (589.1±147.6 ng/L vs. 531.7±74.3 ng/L, p<0.02). The FF cbln1 levels of control participants without PCOS were significantly higher than their serum cbln1 levels (599.3±211.5 ng/L vs. 525.3±87.0 ng/L, p=0.01). Positive correlations were detected among body mass index, insulin resistance, serum insulin, total testosterone, and betatrophin levels in the PCOS group.

Conclusion

Follicular fluid betatrophin and cbln1 concentrations may play a pivotal role on follicular growth in PCOS subjects undergoing IVF/ICSI with an antagonist protocol.

Assessment of circulating betatrophin concentrations in lean glucose-tolerant women with polycystic ovary syndrome

The aims of the current study were to investigate the betatrophin levels in lean glucose-tolerant women with polycystic ovary syndrome (PCOS), and to explore the relationships between these levels and antropometric, hormonal and metabolic parameters. The study population consisted of 50 lean (body mass index [BMI] < 25 kg/m²) women diagnosed with PCOS using the Rotterdam criteria, and 60 age- and BMI-matched healthy controls without any features of clinical or biochemical hyperandrogenism. Before recruitment, glucose tolerance was evaluated in all of the subjects using the 2-h 75 g oral glucose-tolerance test, and only those exhibiting normal glucose tolerance were enrolled. Serum betatrophin levels were significantly higher in women with PCOS (median 322.3; range 44.7-1989.3 ng/L) compared to the controls (median 199.9; range 6.2-1912.9 ng/L; p = .005). In the control group, no significant correlation was evident between betatrophin levels and clinical or biochemical parameters. In the PCOS group, betatrophin levels were positively correlated with prolactin levels (r = .286, p = .046) and negatively correlated with BMI (r = -.283, p = .049), waist/hip ratio (r = -.324, p = .023), and low-density lipoprotein cholesterol levels (r = -.385, p = .006). Impact statement What is already known on this subject: Several studies have suggested that primary alteration in beta-cell function is a pathophysiological feature of PCOS, and insulin resistance is the most significant predictor of beta-cell dysfunction independent of obesity. Betatrophin is a circulating protein that is primarily expressed in the liver in humans. Early experimental investigations demonstrated that overexpression of betatrophin significantly promoted pancreatic beta-cell proliferation, insulin production and improved glucose tolerance. Few studies have investigated the association between PCOS and betatrophin. However, in contrast to our study, the authors included overweight/obese patients and glucose tolerance was not evaluated before recruitment. What the results of this study add: Our results showed that serum betatrophin levels were significantly higher in lean glucose-tolerant PCOS women than in age- and BMI-matched healthy controls. What are the implications of these findings for clinical practice and/or further research: Elevated betatrophin levels in PCOS women, in the absence of obesity and glucose intolerance, may reflect a compensatory mechanism in order to counteract metabolic syndrome-related risk factors.

Association of betatrophin with metabolic characteristics in overweight/obese and lean women with PCOS

As a new hormone, betatrophin has gained attention as a potential new target to combat insulin resistance (IR) and diabetes. Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder among women of the reproductive age with long term sequelae which include IR and metabolic syndrome. The aim of this study is to evaluate the circulating plasma betatrophin levels in overweight/obese or lean women with or without PCOS and also to elucidate possible correlations with anthropometric and metabolic parameters. Thirty-two patients with PCOS as well as fifty-three control subjects were enrolled after obtaining informed written consent. Clinical and biochemical parameters of all subjects were determined. Plasma adiponectin, GLP-1 and betatrophin levels were measured by ELISA. Plasma betatrophin levels were significantly increased in lean patients with PCOS compared with lean and obese controls. Moreover, in PCOS group, betatrophin levels were significantly negatively correlated with waist hip ratio (WHR), fasting insulin level (FINS) and HOMA-IR, whereas, significantly positively correlated with adiponectin level. Multiple regression analysis showed that HOMA-IR was an independent factor influencing serum betatrophin levels. Further follow-up studies are needed to highlight whether and how increased betatrophin secretion play an important role in IR and carbohydrates metabolism in patients with PCOS.

Novel adipokines WISP1 and betatrophin in PCOS: relationship to AMH levels, atherogenic and metabolic profile

OBJECTIVE

To determine the levels of WISP1 and betatrophin in normal weight and obese women with polycystic ovary syndrome (PCOS) and to assess their relationship with anti-Müllerian hormone (AMH) levels, atherogenic profile and metabolic parameters Methods: In this prospective cross-sectional study, the study group was composed of 49 normal weighed and 34 obese women with PCOS diagnosed based on the Rotterdam criteria; 36 normal weight and 26 obese age matched non-hyperandrogenemic women with regular menstrual cycle. Serum WISP1, betatrophin, homeostasis model assessment of insulin resistance (HOMA-IR) and AMH levels were evaluated. Univariate and multivariate analyses were performed between betatrophin, WISP1 levels and AMH levels, metabolic and atherogenic parameters.

RESULTS

Serum WISP1 and betatrophin values were elevated in the PCOS group than in the control group. Moreover, serum WISP1 and betatrophin levels were higher in the obese PCOS subgroup than in normal weight and obese control subgroups. Multivariate analyses revealed that Body mass index, HOMA-IR, AMH independently and positively predicted WISP1 levels. Serum betatrophin level variability was explained by homocysteine, HOMA-IR and androstenedione levels.

CONCLUSION

WISP1 and betatrophin may play a key role on the pathogenesis of PCOS.

Serum betatrophin levels are increased and associated with insulin resistance in patients with polycystic ovary syndrome

Objective

Betatrophin is a newly identified circulating protein that is significantly associated with type 2 diabetes mellitus (T2DM), adiposity, and metabolic syndrome. The aim of this study was to investigate whether betatrophin levels and polycystic ovary syndrome (PCOS) were associated.

Methods

Circulating betatrophin levels were measured in 162 patients with PCOS and 156 matched control females using specific enzyme-linked immunosorbent assay kits. Correlations between betatrophin levels and PCOS incidence as well as multiple key endocrine PCOS parameters were analyzed using multiple statistical methods.

Results

Betatrophin levels were significantly increased in patients with PCOS (685.3 ± 27.7 vs. 772.6 ± 42.5 pg/ml). When sub-grouping all investigated subjects according to the presence of insulin resistance, women with PCOS and insulin resistance exhibited markedly higher betatrophin concentrations. Furthermore, betatrophin levels were significantly correlated with fasting insulin levels and homeostatic model assessment of insulin resistance only in females with PCOS (r = 0.531 and r = 0.628, respectively).

Conclusion

We provide the first report that betatrophin is strongly associated with PCOS. This study suggests that betatrophin may potentially serve as an independent predictor for the development of PCOS in at-risk women, especially those with insulin resistance.

Serum Concentrations of Betatrophin and Its Association with Indirect Indices of Insulin Resistance and Beta Cell Function in Women with Polycystic Ovary Syndrome

INTRODUCTION

Data underline the role of betatrophin in glucose homeostasis. Polycystic ovary syndrome (PCOS) is characterized by insulin resistance (IR). The aim of our study was to investigate the relationship of serum betatrophin concentrations with indirect indices of IR and insulin secretion in women with PCOS, compared to the control group.

METHODS

The study group comprised 43 women with PCOS and 16 controls. IR was assessed by HOMA-IR and Matsuda index. Insulin secretion was evaluated with HOMA-B. An oral glucose tolerance test (OGTT) with estimation of serum betatrophin concentrations was performed.

RESULTS

Glucose load resulted in an increase in serum betatrophin concentrations in the control group (p = 0.02). Serum betatrophin concentrations at 120 min of OGTT were lower in women with PCOS than in the control group (p = 0.02). We observed positive correlations between baseline serum betatrophin concentrations and HOMA-IR (r = 0.39, p = 0.008), negative correlations with Matsuda index (r = -0.31, p = 0.004), and a positive relationship with HOMA-B (r = 0.38, p = 0.01) in women with PCOS. Multiple regression analysis revealed that HOMA-B (β = 0.47, p = 0.001) was an independent factor connected to serum betatrophin levels in PCOS.

CONCLUSIONS

Serum concentrations of betatrophin are connected with insulin resistance and beta cell function and did not change after glucose load in women with PCOS.

The ANGPTL3-4-8 model, a molecular mechanism for triglyceride trafficking

Lipoprotein lipase (LPL) is a rate-limiting enzyme for hydrolysing circulating triglycerides (TG) into free fatty acids that are taken up by peripheral tissues. Postprandial LPL activity rises in white adipose tissue (WAT), but declines in the heart and skeletal muscle, thereby directing circulating TG to WAT for storage; the reverse is true during fasting. However, the mechanism for the tissue-specific regulation of LPL activity during the fed–fast cycle has been elusive. Recent identification of lipasin/angiopoietin-like 8 (Angptl8), a feeding-induced hepatokine, together with Angptl3 and Angptl4, provides intriguing, yet puzzling, insights, because all the three Angptl members are LPL inhibitors, and the deficiency (overexpression) of any one causes hypotriglyceridaemia (hypertriglyceridaemia). Then, why does nature need all of the three? Our recent data that Angptl8 negatively regulates LPL activity specifically in cardiac and skeletal muscles suggest an Angptl3-4-8 model: feeding induces Angptl8, activating the Angptl8–Angptl3 pathway, which inhibits LPL in cardiac and skeletal muscles, thereby making circulating TG available for uptake by WAT, in which LPL activity is elevated owing to diminished Angptl4; the reverse is true during fasting, which suppresses Angptl8 but induces Angptl4, thereby directing TG to muscles. The model suggests a general framework for how TG trafficking is regulated.