Apolipoprotein CIII and Angiopoietin-like Protein 8 are Elevated in Lipodystrophy and Decrease after Metreleptin

Apolipoprotein CIII correlates with lipoproteins in the fed state and is not regulated by leptin administration in states of hypoleptinemia induced by acute or chronic energy deficiency: Results from two randomised controlled trials

BACKGROUND

Medications targeting the leptin and Apolipoprotein CIII (APOC3) pathways are currently under development for the treatment of hypertriglyceridaemia. Given that both pathways are implicated in triglyceride regulation, it is unknown whether they function independently or interact under physiological conditions and under acute or long-term energy deficiency.

METHODS

APOC3 levels and their association with circulating lipids and lipoproteins were evaluated in the context of two randomised controlled studies. In Study-1, 15 healthy individuals were examined under three distinct conditions, each lasting 72 h: isocaloric feeding, fasting with placebo administration and fasting with leptin administered at replacement doses. In Study-2, 20 females with hypoleptinemia due to relative energy deficiency in sport (REDs) for a minimum of 6 months were treated with either leptin or a placebo for 36 weeks.

RESULTS

In Study-1, APOC3 levels remained stable across all arms and were unaffected by leptin administration. In the fed state, APOC3 levels presented positive correlations with various VLDL, IDL, LDL and HDL sizes, and free fatty acids (FFA), most of which were not replicated in fasting. During complete energy deprivation, APOC3 was correlated with HDL molecules, glutamine and FFA, whereas its levels were positively associated only with FFA under leptin treatment. In Study-2, APOC3 levels were lower in the leptin group, but this was not a leptin-dependent effect. A positive correlation between APOC3 levels and HDL was observed in the leptin group.

CONCLUSIONS

These results contribute towards our better understanding of the intricate nature of lipid regulation under energy deficiency, suggesting that medications targeting the leptin and APOC3 pathways act through different metabolic pathways and thus may have independent effects from each other in regulating triglycerides.

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.

Clinical impact of exome sequencing in the setting of a general pediatric ward for hospitalized children with suspected genetic disorders

Background: Genetic conditions contribute a significant portion of disease etiologies in children admitted to general pediatric wards worldwide. While exome sequencing (ES) has improved clinical diagnosis and management over a variety of pediatric subspecialties, it is not yet routinely used by general pediatric hospitalists. We aim to investigate the impact of exome sequencing in sequencing-naive children suspected of having monogenic disorders while receiving inpatient care. Methods: We prospectively employed exome sequencing in children admitted to the general pediatric inpatient service at a large tertiary medical center in Israel. Genetic analysis was triggered by general and/or subspecialist pediatricians who were part of the primary inpatient team. We determined the diagnostic yield among children who were referred for exome sequencing and observed the effects of genetic diagnosis on medical care. Results: A total of fifty probands were evaluated and exome sequenced during the study period. The most common phenotypes included were neurodevelopmental (56%), gastrointestinal (34%), and congenital cardiac anomalies (24%). A molecular diagnosis was reached in 38% of patients. Among seven patients (37%), the molecular genetic diagnosis influenced subsequent clinical management already during admission or shortly following discharge. Conclusion: We identified a significant fraction of genetic etiologies among undiagnosed children admitted to the general pediatric ward. Our results support that early application of exome sequencing may be maximized by pediatric hospitalists' high index of suspicion for an underlying genetic etiology, prompting an in-house genetic evaluation. This framework should include a multidisciplinary co-management approach of the primary care team working alongside with subspecialties, geneticists and bioinformaticians.

APOC-III: a Gatekeeper in Controlling Triglyceride Metabolism

PURPOSE OF REVIEW

Apolipoprotein C-III (ApoC-III) is a widely known player in triglyceride metabolism, and it has been recently recognized as a polyhedric factor which may regulate several pathways beyond lipid metabolism by influencing cardiovascular, metabolic, and neurological disease risk. This review summarizes the different functions of ApoC-III and underlines the recent findings related to its multifaceted pathophysiological role.

RECENT FINDINGS

The role of ApoC-III has been implicated in HDL metabolism and in the development of atherosclerosis, inflammation, and ER stress in endothelial cells. ApoC-III has been recently considered an important player in insulin resistance mechanisms, lipodystrophy, diabetic dyslipidemia, and postprandial hypertriglyceridemia (PPT). The emerging evidence of the involvement of ApoC-III in the in the pathogenesis of Alzheimer's disease open the way to further study if modification of ApoC-III level slows disease progression. Furthermore, ApoC-III is clearly linked to cardiovascular disease (CVD) risk, and progression of coronary artery disease (CAD) as well as the calcification of aortic valve and recent clinical trials has pointed out the inhibition of ApoC-III as a promising approach to manage hypertriglyceridemia and prevent CVD. Several evidences highlight the role of ApoC-III not only in triglyceride metabolism but also in several cardio-metabolic pathways. Results from recent clinical trials underline that the inhibition of ApoC-III is a promising therapeutical strategy for the management of severe hypertriglyceridemia and in CVD prevention.

Assessment of efficacy and safety of volanesorsen for treatment of metabolic complications in patients with familial partial lipodystrophy: Results of the BROADEN study: Volanesorsen in FPLD; The BROADEN Study

BACKGROUND

Volanesorsen, an antisense oligonucleotide, is designed to inhibit hepatic apolipoprotein C-III synthesis and reduce plasma apolipoprotein C-III and triglyceride concentrations.

OBJECTIVE

The present study assessed efficacy and safety of volanesorsen in patients with familial partial lipodystrophy (FPLD) and concomitant hypertriglyceridemia and diabetes.

METHODS

BROADEN was a randomized, placebo-controlled, phase 2/3, 52-week study with open-label extension and post-treatment follow-up periods. Patients received weekly subcutaneous volanesorsen 300 mg or placebo. The primary endpoint was percent change from baseline in fasting triglycerides at 3 months. Secondary endpoints included relative percent change in hepatic fat fraction (HFF), visceral adiposity, and glycated hemoglobin levels.

RESULTS

Forty patients (11 men, 29 women) were enrolled, majority of whom were aged <65 years (mean, 47 years) and White. Least squares mean (LSM) percent change in triglycerides from baseline to 3 months was -88% (95% CI, -134 to -43) in the volanesorsen group versus -22% (95% CI, -61 to 18) in the placebo group, with a difference in LSM of -67% (95% CI, -104 to -30; P=0.0009). Volanesorsen induced a significant LSM relative reduction in HFF of 53% at month 12 versus placebo (observed mean [SD]: 9.7 [7.65] vs. 18.0 [8.89]; P=0.0039). No statistically significant changes were noted in body volume measurements (fat, liver, spleen, visceral/subcutaneous adipose tissue) or glycated hemoglobin. Serious adverse events in patients assigned to volanesorsen included 1 case each of sarcoidosis, anaphylactic reaction, and systemic inflammatory response syndrome.

CONCLUSION

In BROADEN, volanesorsen significantly reduced serum triglyceride levels and hepatic steatosis in patients with FPLD.

Metreleptin treatment of non-HIV lipodystrophy syndromes

Lipodystrophy syndromes (LS) constitute a group of rare diseases of the adipose tissue, characterized by a complete or selective deficiency of the fat mass. These disorders are associated with important insulin resistance, cardiovascular and metabolic comorbidities that impact patient's survival and quality of life. Management is challenging and includes diet, physical activity, and specific pharmacological treatment of LS-associated comorbidities. Because of a common pathophysiology involving decreased concentration of the adipokine leptin, efforts have been made to develop therapeutic strategies with leptin replacement therapy. Metreleptin, a recombinant human leptin analogue, has been proposed in hypoleptinemic patients since the beginning of 2000's. The treatment leads to an improvement in metabolic parameters, more important in generalized than in partial LS forms. In this review, the current knowledge about the development of the drug, its outcomes in the treatment of lipodystrophic patients as well as the peculiarities of its use will be presented.

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.