Changes in serum levels of angiopoietin-like protein-8 and glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 after ezetimibe therapy in patients with dyslipidemia

Relationship between serum levels of ANGPTL8, Apo C2, and human placental lactogen (hPL) in patients with gestational diabetes mellitus: Interaction of LPL regulators with hPL, a possible contributing factor to insulin resistance

INTRODUCTION

Gestational diabetes mellitus (GDM) is defined as glucose intolerance during pregnancy. We aimed to investigate the potential effects of betatrophin and ApoC2 in GDM, focusing on their roles in LPL (lipoprotein lipase) regulation and their relationship with hPL to elucidate the possible impact of hPL on lipid metabolism and its potential contribution to the development of GDM.

METHODS

Thirty pregnant women with normal glucose tolerance and 29 with gestational diabetes mellitus (diagnosed by 75g OGTT between 24 and 28 weeks) were included in the study. Serum betatrophin, hPL, and ApoC2 were measured by Elisa and HOMA-IR was calculated.

RESULTS

In the GDM group, hPL levels correlated with betatrophin and ApoC2 (r = 0.552, p < 0.05; r = 0.588, p < 0.05 respectively) while betatrophin correlated with the ApoC2 (r = 0.584, p < 0.05). A linear relationship between hPL and betatropin and also between hPL and ApoC2 values in the control group (r = 0.454, p < 0.05; r = 0.779, p < 0.01 respectively) were observed. ApoC2 levels in the GDM group (n = 20) with HOMA-IR cut-off >2.5 were significantly higher than the control group (n = 10) (p < 0.05). There was also a positive relationship between betatrophin and ApoC2 (r = 0.591) (p < 0.05).

DISCUSSION

GDM patients may have impaired LPL enzyme regulation in addition to insulin resistance, with hPL potentially contributing to this disruption. Impaired lipoprotein lipase activity and its dysregulation secondary to genetic disorders may play a role in the etiopathogenesis of GDM. Further investigation into the correlation between betatrophin, ApoC2, and other LPL modulators in patients with various forms of diabetes could be beneficial for understanding this interaction more comprehensively.

Gender-Dependent Associations between Serum Betatrophin Levels and Lipoprotein Subfractions in Diabetic and Nondiabetic Obese Patients

Betatrophin, also known as angiopoietin-like protein 8 (ANGPTL8), mainly plays a role in lipid metabolism. To date, associations between betatrophin and lipoprotein subfractions are poorly investigated. For this study, 50 obese patients with type 2 diabetes (T2D) and 70 nondiabetic obese (NDO) subjects matched in gender, age, and body mass index (BMI) as well as 49 gender- and age-matched healthy, normal-weight controls were enrolled. Serum betatrophin levels were measured with ELISA, and lipoprotein subfractions were analyzed using Lipoprint gel electrophoresis. Betatrophin concentrations were found to be significantly higher in the T2D and NDO groups compared to the controls in all subjects and in females, but not in males. We found significant positive correlations between triglyceride, very low density lipoprotein (VLDL), large LDL (low density lipoprotein), small LDL, high density lipoprotein (HDL) -6-10 subfractions, and betatrophin, while negative correlations were detected between betatrophin and IDL, mean LDL size, and HDL-1-5. Proportion of small HDL was the best predictor of betatrophin in all subjects. Small LDL and large HDL subfractions were found to be the best predictors in females, while in males, VLDL was found to be the best predictor of betatrophin. Our results underline the significance of serum betatrophin measurement in the cardiovascular risk assessment of obese patients with and without T2D, but gender differences might be taken into consideration.

Relationship Between Serum Betatrophin, GPIHBP1, and LDL Subfractions in Patients With Gestational Diabetes Mellitus

OBJECTIVES

Gestational diabetes mellitus (GDM) leads to changes in the lipid metabolism. In this study, we aimed to compare serum levels of LDL subfractions, betatrophin, and glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 (GPIHBP1) between patients with GDM and healthy pregnant women.

DESIGN AND METHODS

We designed a prospective case-control study with 41 pregnant women. Subjects were divided into two groups: GDM and control. Betatrophin and GPIHBP1 levels were measured by ELISA method. Lipoprint LDL subfraction kit was used to perform LDL subfraction analysis electrophoretically.

RESULTS

Serum levels of LDL6 subfraction, betatrophin, and GPIHBP1 were found to be higher in GDM group compared to the controls (p<0.001). The mean LDL size were also found larger in GDM group. A positive correlation was found between betatrophin and GPIHBP1 levels (rho=0.96, p<0.001).

CONCLUSIONS

Our findings suggest that betatrophin, and GPIHBP1 levels were found to be increased in GDM. This maybe the result of adaptive mechanisms in response to insulin resistance, but also this relationship should be evaluated for their effects on impaired lipid metabolism and lipoprotein lipase metabolism. There is a need for further prospective studies with larger samples to fully elucidate the mechanisms of this relationship both in pregnant patients and the other patient groups.

Association between ANGPTL3, 4, and 8 and lipid and glucose metabolism markers in patients with diabetes

Lipid management, especially with respect to triglyceride (TG) metabolism, in patients with diabetes is not sufficient with current therapeutic agents, and new approaches for improvement are needed. Members of the angiopoietin-like protein (ANGPTL) family, specifically ANGPTL3, 4, and 8, have been reported as factors that inhibit lipoprotein lipase (LPL) activity and affect TGs. The present study investigated the association between lipid and glucose metabolism markers and the mechanism by which these proteins affect lipid metabolism. A total of 84 patients hospitalized for diabetes treatment were evaluated. Lipid and glucose metabolism markers in blood samples collected before breakfast, on the day after hospitalization, were analyzed. ANGPTL8 showed a significant positive correlation with TG values. HDL-C values displayed a significant positive correlation with ANGPTL3 but a negative correlation with ANGPTL4 and ANGPTL8. The results did not indicate a significant correlation among ANGPTL3, 4, and 8 levels. Thus, it is possible that the distribution of these proteins differs among patients. When patients were divided into groups according to the levels of ANGPTL3 and ANGPTL8, those with high levels of both ANGPTL3 and ANGPTL8 also had high levels of TG and small dense LDL-C/LDL-C (%). Multiple regression analysis indicated that low LPL, high ApoC2, high ApoC3, high ApoE, and high ANGPTL8 levels were the determinants of fasting hypertriglyceridemia. By contrast, no clear association was observed between any of the ANGPTLs and glucose metabolism markers, but ANGPTL8 levels were positively correlated with the levels of HOMA2-IR and BMI. Patients with high levels of both ANGPTL3 and ANGPTL8 had the worst lipid profiles. Among ANGPTL3, 4, and 8, ANGPTL8 is more important as a factor determining plasma TG levels. We anticipate that the results of this research will facilitate potential treatments targeting ANGPTL8 in patients with diabetes.