Exercise Lowers Plasma Angiopoietin-Like 2 in Men with Post-Acute Coronary Syndrome

Angiopoietin-Like Proteins: Cardiovascular Biology and Therapeutic Targeting for the Prevention of Cardiovascular Diseases

Despite the best pharmacologic tools available, cardiovascular diseases (CVDs) remain a major cause of morbidity and mortality in developed countries. After 2 decades of research, new therapeutic targets, such as angiopoietin-like proteins (ANGPTLs), are emerging. ANGPTLs belong to a family of 8 members, from ANGPTL1 to ANGPTL8; they have structural homology with angiopoietins and are secreted in the circulation. ANGPTLs display a multitude of physiological and pathologic functions; they contribute to inflammation, angiogenesis, cell death, senescence, hematopoiesis, and play a role in repair, maintenance, and tissue homeostasis. ANGPTLs-particularly the triad ANGPTL3, 4, and 8-have an established role in lipid metabolism through the regulation of triacylglycerol trafficking according to the nutritional status. Some ANGPTLs also contribute to glucose metabolism. Therefore, dysregulation in ANGPTL expression associated with abnormal circulating levels are linked to a plethora of CVD and metabolic disorders including atherosclerosis, heart diseases, diabetes, but also obesity and cancers. Because ANGPTLs bind to different receptors according to the cell type, antagonists are therapeutically inadequate. Recently, direct inhibitors of ANGPTLs, mainly ANGPTL3, have been developed, and specific monoclonal antibodies and antisense oligonucleotides are currently being tested in clinical trials. The aim of the current review is to provide an up-to-date preclinical and clinical overview on the function of the 8 members of the ANGPTL family in the cardiovascular system, their contribution to CVD, and the therapeutic potential of manipulating some of them.

Angptl2 is a Marker of Cellular Senescence: The Physiological and Pathophysiological Impact of Angptl2-Related Senescence

Cellular senescence is a cell fate primarily induced by DNA damage, characterized by irreversible growth arrest in an attempt to stop the damage. Senescence is a cellular response to a stressor and is observed with aging, but also during wound healing and in embryogenic developmental processes. Senescent cells are metabolically active and secrete a multitude of molecules gathered in the senescence-associated secretory phenotype (SASP). The SASP includes inflammatory cytokines, chemokines, growth factors and metalloproteinases, with autocrine and paracrine activities. Among hundreds of molecules, angiopoietin-like 2 (angptl2) is an interesting, although understudied, SASP member identified in various types of senescent cells. Angptl2 is a circulatory protein, and plasma angptl2 levels increase with age and with various chronic inflammatory diseases such as cancer, atherosclerosis, diabetes, heart failure and a multitude of age-related diseases. In this review, we will examine in which context angptl2 was identified as a SASP factor, describe the experimental evidence showing that angptl2 is a marker of senescence in vitro and in vivo, and discuss the impact of angptl2-related senescence in both physiological and pathological conditions. Future work is needed to demonstrate whether the senescence marker angptl2 is a potential clinical biomarker of age-related diseases.

Serum Angiopoietin-Like Protein 2 and NT-Pro BNP Levels and Their Associated Factors in Patients with Chronic Heart Failure Participating in a Phase III Cardiac Rehabilitation Program

Angiopoietin-like protein 2 (ANGPTL2) promotes chronic inflammation and plays a key role in the pathogenesis of heart failure. Cardiac rehabilitation (CR) is an integral component of heart failure management and has been shown to have anti-inflammatory effects. However, ANGPTL2 concentration in chronic heart failure patients undergoing CR has not been evaluated. This study aimed to investigate serum ANGPTL2 levels and their associated factors and compare the results with those of N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with chronic heart failure undergoing phase III CR.A total of 56 patients were enrolled. Clinical characteristics including body composition, grip strength, exercise tolerance, duration of CR, blood counts and biochemistry, and echocardiographic parameters were evaluated for their association with serum ANGPTL2 and NT-proBNP levels.The median (first and third quartiles) value of ANGPTL2 was 4.05 (2.70-5.57) ng/mL. Clinical parameters that correlated with serum ANGPTL2 levels were body weight, body mass index, body fat mass, body fat percentage, anaerobic threshold (AT), C-reactive protein, and total protein (TP), which were mostly distinct from those that correlated with serum NT-proBNP levels. A multivariate analysis revealed that AT and TP were independent factors related to ANGPTL2 levels, whereas age, left ventricular ejection fraction, and left atrial dimension were independently related to NT-proBNP levels.These observations suggest that CR increases the exercise tolerance and exhibits anti-inflammatory effects simultaneously, and this situation is reflected by decreased serum ANGPLT2 and TP levels. ANGPTL2 may be a useful marker of inflammation and impaired exercise tolerance in patients with chronic heart failure.

Knockdown of angiopoietin-like 2 induces clearance of vascular endothelial senescent cells by apoptosis, promotes endothelial repair and slows atherogenesis in mice

Elimination of senescent cells (SnC) is anti-atherogenic, but the specific contribution of senescent vascular endothelial cells (EC) is unknown. We inactivated angiopoietin like-2 (angptl2), a marker of SnEC and a pro-atherogenic cytokine in LDLr^-/-, hApoB₁₀₀^+/+ atherosclerotic (ATX) mice. Three months after a single vascular delivery of a small hairpin (sh)Angptl2 in 3-month old ATX mice using an adeno-associated virus serotype 1 (AAV1), aortic atheroma plaque progression was slowed by 58% (p<0.0001). In the native aortic endothelium, angptl2 expression was decreased by 80%, in association with a reduced expression of p21, a cyclin-dependent kinase inhibitor overexpressed in growth-arrested SnC. Endothelial activation was reduced (lower Icam-1, Il-1β and Mcp-1 expression), decreasing monocyte Cd68 expression in the endothelium. One week post-injection, the ratio Bax/Bcl2 increased in the endothelium only, suggesting that angptl2⁺/p21⁺ SnEC were eliminated by apoptosis. Four weeks post-injection, the endothelial progenitor marker Cd34 increased, suggesting endothelial repair. In arteries of atherosclerotic patients, we observed a strong correlation between p21 and ANGPTL2 (r=0.727, p=0.0002) confirming the clinical significance of angptl2-associated senescence. Our data suggest that therapeutic down-regulation of vascular angptl2 leads to the clearance of SnEC by apoptosis, stimulates endothelial repair and reduces atherosclerosis.

Moderate-intensity continuous exercise is superior to high-intensity interval training in the proportion of VO2peak responders after ACS

INTRODUCTION AND OBJECTIVES

We compared the effects of 12 weeks of low-volume high-intensity interval training (LV-HIIT) vs moderate-intensity continuous exercise training (MICET) on cardiopulmonary exercise test parameters and the proportion of non/low responders (NLR) to exercise training in post-acute coronary syndrome (ACS) patients.

METHODS

Patients with a recent ACS were randomized to LV-HIIT, MICET, or a usual care group. LV-HIIT consisted of 2 to 3 sets of 6 to 10minutes with repeated bouts of 15 to 30seconds at 100% of peak workload alternating with 15 to 30seconds of passive recovery. Cardiopulmonary exercise test parameters were assessed, and key exercise variables were calculated. Training response was assessed according to the median VO_2peak change post vs pretraining in the whole cohort (stratification NLR vs high response).

RESULTS

Fifty patients were included in the analysis (LV-HIIT, n=23; MICET, n=18; usual care, n=9) and 74% were male. The proportion of NLR was higher in the LV-HIIT group than in the MICET group (LV-HIIT 61%, MICET 21%, and usual care 80%; P=.0040). VO_2peak-dependent variables (VO_2peak, percent-predicted VO_2peak) improved in both training groups (P=.002 and P <.0001 for time with LV-HIIT and MICET, respectively), but the improvement was more pronounced with MICET (P=.004 and P=.001 for interaction, respectively). The ΔVO₂/Δworkload slope improved only with MICET (P=.021).

CONCLUSIONS

In patients with a recent ACS, several prognostic VO_2peak-dependent variables were improved after LV-HIIT, but the improvement was more pronounced or only found after MICET. Low-volume HIIT resulted in a higher proportion of NLR than isocaloric MICET. Clinical trialsregistered at ClinicalTrials.gov (Identifiers: NCT03414996 and NCT02048696).

The impact of high-intensity interval training on ventricular remodeling in patients with a recent acute myocardial infarction-A randomized training intervention pilot study

Background

Aerobic exercise training is associated with beneficial ventricular remodeling and an improvement in cardiac biomarkers in chronic stable heart failure. High‐intensity interval training (HIIT) is a time‐efficient method to improve V˙O2peak in stable coronary heart disease patients. This pilot study aimed to compare the effect of HIIT on ventricular remodeling in patients with a recent acute myocardial infarction (AMI).

Methods

Nineteen post‐AMI patients were randomized to either HIIT (n = 9) or usual care (n = 10). A cardiopulmonary exercise test (CPET), transthoracic echocardiography, and cardiac biomarker assessment (ie, N‐terminal pro B‐type natriuretic peptide levels and G protein‐coupled receptor kinase 2 expression) were performed before and after a 12‐week training intervention. CPET parameters including oxygen uptake efficiency slope (OUES) and V˙O2 at the first ventilatory threshold (V˙O2 VT1) were calculated. left ventricular (LV) structural and functional echocardiographic parameters including myocardial strain imaging were assessed.

Results

V˙O2peak and OUES improved solely in the HIIT group (P < .05 for group/time, respectively). There was a significant training effect for the improvement of peak work load in both groups (P < .05). O₂ pulse and V˙O2 at VT1 both improved only in the HIIT group (P < .05 for time, no interaction). HIIT improved radial strain and pulsed‐wave tissue Doppler imaging derived e′ (P < .05 for time, no interaction). Cardiac biomarkers did not change in either group.

Conclusions

In post‐AMI patients, HIIT lead to significant improvements in prognostic CPET parameters compared to usual care. HIIT was associated with favorable ventricular remodeling regarding certain echocardiographic parameters of LV function.

Reduction of plasma angiopoietin-like 2 after cardiac surgery is related to tissue inflammation and senescence status of patients

OBJECTIVES

A strong relationship between high circulating angiopoietin-like 2 (ANGPTL2) levels, a proinflammatory adipokine, and cardiovascular diseases has been reported. Our objective was to determine whether plasma ANGPTL2 and high-sensitivity C-reactive protein (hs-CRP) levels change postoperatively in patients who underwent heart valve surgery and/or coronary artery bypass grafting. We hypothesized that a corrective cardiac surgery would decrease ANGPTL2 levels.

METHODS

In 47 prospectively recruited patients who underwent coronary artery bypass grafting (n = 16), valve replacement (n = 16), or both (n = 15), we measured plasma ANGPTL2 and hs-CRP levels preoperatively, at 24 hours, at 3 to 5 days (hospital discharge), and at 30 to 90 days (follow-up) after surgery. Mediastinal adipose tissue and distal fragments of the left internal mammary artery (IMA) were harvested during surgery and mRNA expression of inflammatory and senescence markers was assessed using real-time quantitative polymerase chain reaction.

RESULTS

ANGPTL2 and hs-CRP levels were elevated 24 hours after surgery and then returned to baseline levels. We noted, however, a dichotomy among patients: compared with baseline, plasma ANGPTL2 levels either significantly decreased (n = 21/47) or increased (n = 26/47) after surgery. In contrast, hs-CRP levels were identical between groups (P = .997). Patients in the increased group were older (P = .002) with a higher systolic blood pressure (P = .038) at baseline. Moreover, changes in ANGPTL2 levels (ΔANGPTL2 = final minus initial levels) positively correlated with mRNA expression of tumor necrosis factor α and interleukin 8 in mediastinal adipose tissue and IMA (P < .05) and with the senescence-associated marker cyclin-dependent kinase inhibitor 1 in IMA (P = .009).

CONCLUSIONS

In younger patients with lower levels of tissue inflammation and arterial senescence load, ANGPTL2, but not hs-CRP levels decreased after cardiac surgery, suggesting that circulating ANGPTL2 reflects tissue inflammation and senescence.

Long-term moderate exercise enhances specific proteins that constitute neurotrophin signaling pathway: A TMT-based quantitative proteomic analysis of rat plasma

Physical exercise has been reported to increase neurotrophin in brain tissues as hippocampus as well as increased neurotrophic level peripherally in blood plasma and might have an effect on/or affect molecular processes of energy metabolism (and homeostasis). In this study, using quantitative proteomic analysis, we obtained a plasma protein profile from the rat with long-term moderate exercise. A total of 752 proteins were identified in the plasma. Among them, 54 proteins were significant up-regulated and 47 proteins were down-regulated in the plasma of exercise group compared with the control group. Bioinformatic analyses showed that these altered proteins are widely involved in multiple biological processes, molecular functions and cellular components, which connect with 11 signaling pathways. Interestingly, 5 up-regulated proteins Rap1b, PTPN11, ARHGDIA, Cdc42 and YWHAE, confirmed by Western blots, are involved in the neurotrophin signaling pathway which shows the lowest P value among the identified pathways. Further analyses showed that the 5 neurotrophin-signaling-pathway-related proteins participate in two important protein-protein interaction networks associated to cell survival and apoptosis, axonal development, synapse formation and plasticity. This study provides an exercise-induced plasma protein profile, suggesting that long-term exercise enhances the proteins involved in neurotrophin signaling pathway which may contribute to health benefit.

SIGNIFICANCE

Physical activity contributes to myriad benefits on body health across the lifespan. The changes in plasma proteins after chronic moderate exercise may be used as biomarkers for health and may also play important roles in increase of cardiovascular fitness, enhancement of immune competence, prevention of obesity, decrease of risk for neurological disorders, cancer, stroke, diabetes and other metabolic disorders. Using a TMT-based proteomic method, this study identified 101 altered proteins in the plasma of rats after long-term moderate treadmill running, which may provide novel biomarkers for further investigation of the underlying mechanism of physical exercise. We confirmed that exercise enhances 5 proteins of the neurotrophin signaling pathway that may contribute to health benefits.

Serum Levels of Angiopoietin-Like Protein 2 and Obestatin in Iranian Women with Polycystic Ovary Syndrome and Normal Body Mass Index

Background: Polycystic ovary syndrome (PCOS) is a common endocrine disease in women of reproduction age and a major cause of anovulatory infertility. Insulin resistance plays an important role in the development and durability of this disorder. ANGPTL2 is known as an inflammatory mediator derived from adipose tissue that links obesity to systemic insulin resistance, and obestatin has been identified as a hormone associated with insulin resistance that suppresses food reabsorption, inhibits gastric emptying and decreases weight gain. The aim of this study was to evaluate serum levels of ANGPTL2 and obestatin in PCOS women with normal body mass index (BMI). Methods: In this case-control study, 26 PCOS women based on the Rotterdam 2003 diagnostic criteria as the case group and 26 women with normal menstrual cycles as the control group were enrolled. Serum levels of ANGPTL2, obestatin, insulin and other hormone factors related with PCOS were measured by ELISA method and biochemical parameters were measured by an autoanalyzer. Data were analyzed by independent samples-T test, Chi Square, Correlation and a single sample Kolmogrov–Smirnov test using SPSS software, version 16. Results: There were no significant variations in the amount of ANGPTL2, obestatin, cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein, cholesterol, creatinine and dehydroepiandrosterone-sulfate between the two groups. There were significant increases in serum levels of fasting blood sugar (p = 0.01), insulin (p = 0.04), homeostasis model assessments of insulin resistance (p = 0.04), testosterone (p = 0.02), luteinizing hormone (p = 0.004), luteinizing hormone/follicle stimulating hormone (p = 0.006) and prolactin (p = 0.04) in case group compared to the control group. A significant positive correlation was observed between ANGPTL2 and insulin (p = 0.02), HOMA-IR (p = 0.01) and, on the other hand, a significant negative correlation was observed between obestatin and insulin (p = 0.01), HOMA-IR (p = 0.008) in PCOS group. Conclusions: In this study, no significant variations were observed in serum levels of ANGPTL2 and obestatin in PCOS women with normal BMI.

High Circulating Levels of ANGPTL2: Beyond a Clinical Marker of Systemic Inflammation

Angiopoietin-like 2 (ANGPTL2) is a proinflammatory protein belonging to the angiopoietin-like family. ANGPTL2 is secreted and detected in the systemic circulation. Different observational clinical studies reported that circulating levels of ANGPTL2 increase significantly in various chronic inflammatory diseases and showed associations between ANGPTL2 levels and diagnosis and/or prognosis of cardiovascular diseases, diabetes, chronic kidney disease, and various types of cancers. However, these studies did not address the following questions: (a) what are the sources of circulating ANGPTL2? (b) How and by which mechanisms an increase in circulating ANGPTL2 contributes to the pathogenesis of chronic inflammatory diseases? (c) Does an increase in circulating levels of ANGPTL2 measured in a well-defined chronic medical condition originate from a specific cell type? Mechanistic hypotheses have been proposed based on studies performed in mice and cultured cells, and proinflammatory, prooxidative, proangiogenic, proliferative, and antiapoptotic properties of ANGPTL2 have been reported. The aim of this review is to propose answers concerning the potential sources of circulating ANGPTL2 and its common pathological properties associated with various chronic inflammatory diseases and death in humans. We believe that high circulating ANGPTL2 levels are more than an inflammatory marker and may reflect the senescent cellular load of an individual.