Arash Alipour

Leukocyte Activation by Triglyceride-Rich Lipoproteins

Objective—Postprandial lipemia has been linked to atherosclerosis and inflammation. Because leukocyte activation is obligatory for atherogenesis, leukocyte activation by triglyceride-rich lipoproteins (TRLs) was investigated. Methods and Results—The expression of CD11b and CD66b after incubation with glucose and native and artificial TRLs (NTRL and ATRL) in vivo and in vitro was evaluated by flowcytometry. Oral fat loading tests showed an increased expression of CD11b on monocytes and neutrophils and CD66b on neutrophils. In 11 volunteers, postprandial leukocytes became enriched with meal-derived fatty acids ([1-13C]16:0) suggesting uptake of exogenous fat. ApoB binding on leukocytes measured by flowcytometry in 65 subjects was highest on neutrophils and monocytes suggesting adherence of apoB-containing lipoproteins. Physiological concentrations of TRLs showed 62% increased neutrophil CD11b and a dose-dependent increased monocyte CD11b up to 84% in vitro. Incubations with lipid emulsions in the hypertriglyceridemic range showed a 5-fold increased monocyte CD11b expression, which was higher than the positive control (fMLP), and a dose-dependent 2- to 3-fold increased neutrophil CD11b and CD66b. The oxidative scavenger DMTU decreased the neutrophil CD66b expression by 36%. Conclusion—Acute hypertriglyceridemia is a leukocyte activator most likely by direct interaction between TRLs and leukocytes and uptake of fatty acids. TG-mediated leukocyte activation is an alternative proinflammatory and proatherogenic mechanism of hypertriglyceridemia in part associated to the generation of oxidative stress.

Novel aspects of postprandial lipemia in relation to atherosclerosis

Postprandial hyperlipidemia is considered to be a substantial risk factor for atherosclerosis. Interestingly, this concept has never been supported by randomized clinical trials. The difficulty lies in the fact that most interventions aimed to reduce postprandial lipemia, will also affect LDL-C levels. The atherogenic mechanisms of postprandial lipids and lipoproteins can be divided into direct lipoprotein-mediated and indirect effects; the latter, in part, by inducing an inflammatory state. Elevations in postprandial triglycerides (TG) have been related to the increased expression of postprandial leukocyte activation markers, up-regulation of pro-inflammatory genes in endothelial cells and involvement of the complement system. This set of events is part of the postprandial inflammatory response, which is one of the recently identified potential pro-atherogenic mechanisms of postprandial lipemia. Especially, complement component 3 levels show a close correlation with postprandial lipemia and are also important determinants of the metabolic syndrome. In clinical practice, fasting TG are frequently used as reflections of postprandial lipemia due to the close correlation between the two. The use of serial capillary measurements in an out-of-hospital situation is an alternative for oral fat loading tests. Daylong TG profiles reflect postprandial lipemia and are increased in conditions like the metabolic syndrome, type 2 diabetes and atherosclerosis. Studies are needed to elucidate the role of postprandial inflammation in atherogenesis and to find new methods in order to reduce selectively the postprandial inflammatory response. Future studies are needed to find new methods in order to reduce selectively the postprandial inflammatory response.

Postprandial inflammation and endothelial dysfuction

Postprandial hyperlipidaemia is a common metabolic disturbance in atherosclerosis. During the postprandial phase, chylomicrons and their remnants can penetrate the intact endothelium and cause foam cell formation. These particles are highly atherogenic after modification. People in the Western world are non-fasting for most of the day, which consequently leads to a continuous challenge of the endothelium by atherogenic lipoproteins and their remnants. Furthermore, atherosclerosis is considered a low-grade chronic inflammatory disease. Many studies have shown that the process of atherogenesis in part starts with the interaction between the activated leucocytes and activated endothelium. Postprandial lipoproteins can activate leucocytes in the blood and up-regulate the expression of leucocyte adhesion molecules on the endothelium, facilitating adhesion and migration of inflammatory cells into the subendothelial space. Another inflammatory process associated with postprandial lipaemia is the activation of the complement system. Its central component C3 has been associated with obesity, coronary sclerosis, the metabolic syndrome and fasting and postprandial TAGs (triacylglycerols). Moreover, chylomicrons are the strongest stimulators of adipocyte C3 production via activation of the alternative complement cascade. A postprandial C3 increment has been shown in healthy subjects and in patients with CAD (coronary artery disease) and with FCHL (familial combined hyperlipidaemia). Postprandial lipaemia has been related to TAG and free fatty acid metabolism. All of these mechanisms provide an alternative explanation for the atherogenicity of the postprandial period.

Survival of Transcatheter Mitral Valve Repair Compared With Surgical and Conservative Treatment in High-Surgical-Risk Patients

OBJECTIVES The goal of this study was to compare survival between transcatheter mitral valve (MV) repair using MitraClip system (Abbott Vascular, Santa Clara, California), MV-surgery, and conservative treatment in high-surgical-risk patients symptomatic with severe mitral valve regurgitation (MR). BACKGROUND Up to 50% of patients with symptomatic severe MR are denied for surgery due to high perioperative risk. Transcatheter MV repair might be an alternative. METHODS Consecutive patients (n = 139) treated with transcatheter MV repair were included. Comparator surgically (n = 53) and conservatively (n = 59) treated patients were identified retrospectively. Surgical risk was based on the logistic European System for Cardiac Operative Risk Evaluation (log EuroSCORE) or the presence of relevant risk factors, as judged by the heart team. RESULTS The log EuroSCORE was higher in the transcatheter MV repair group (23.9 ± 16.1%) than in the surgically (14.2 ± 8.9%) and conservatively (18.7 ± 13.2%, p < 0.0001) treated patients. Left ventricular ejection fraction was higher in surgical patients (43.9 ± 14.4%, p = 0.003), with similar values for the transcatheter MV repair (36.8 ± 15.3%) and conservatively treated (34.5 ± 16.5%) groups. After 1 year of follow-up, the transcatheter MV repair and surgery groups showed similar survival rates (85.8% and 85.2%, respectively), whereas 67.7% of conservatively treated patients survived. The same trend was observed after the second and third years. After weighting for propensity score and controlling for risk factors, both the transcatheter MV repair (hazard ratio [HR]: 0.41, 95% confidence interval [CI]: 0.22 to 0.78, p = 0.006) and surgical (HR: 0.52, 95% CI: 0.30 to 0.88, p = 0.014) groups showed better survival than the conservatively treated group. The transcatheter MV repair and surgical groups did not differ (HR: 1.25, 95% CI: 0.72 to 2.16, p = 0.430). CONCLUSIONS Despite a higher log EuroSCORE, high-surgical-risk patients with symptomatic severe MR treated with transcatheter MV repair show similar survival rates compared with surgically treated patients, with both displaying survival benefit compared with conservative treatment.

Exploring the value of apoB48 as a marker for atherosclerosis in clinical practice.

Eur J Clin Invest 2012; 42 (7): 702–708

Glucose-dependent leukocyte activation in patients with type 2 diabetes mellitus, familial combined hyperlipidemia and healthy controls

BACKGROUND Leukocyte activation has been associated with vascular complications in type 2 diabetes mellitus (T2DM). Hyperglycemia may be involved in this leukocyte activation. Our aim was to investigate the role of elevated glucose concentrations on leukocyte activation in patients with a wide range of insulin sensitivity. METHODS Leukocyte activation was determined after ingestion of 75 gram glucose in subjects with T2DM, familial combined hyperlipidemia (FCH) and healthy controls. Leukocyte activation markers were measured by flow cytometry. Postprandial changes were calculated as the area under the curve (AUC), and the incremental area under the curve corrected for baseline values (dAUC). RESULTS 51 Subjects (20 T2DM, 17 FCH and 14 controls) were included. Fasting neutrophil CD66b expression and CD66b-AUC were respectively 36% and 39% higher in T2DM patients than in controls (p=0.004 and p=0.003). Fasting neutrophil CD66b expression correlated positively with glucose-AUC (Spearmans rho 0.481, p<0.001) and HbA1c (rho 0.433, p=0.002). Although fasting monocyte CD11b expression was not significantly different between subjects, monocyte CD11b-AUC was 26% higher in T2DM than in controls (p=0.006). Similar trends were observed for FCH patients. Monocyte CD11b-dAUC correlated positively with glucose-AUC (rho 0.322, p=0.022) and HbA1c (rho 0.319, p=0.023). CONCLUSIONS These data suggest that both acute and chronic hyperglycemia, associated with insulin resistance as seen in T2DM and FCH, are involved in the increased fasting and postprandial leukocyte activation observed in these conditions.

Erythrocyte-associated apolipoprotein B and its relationship with clinical and subclinical atherosclerosis

Eur J Clin Invest 2012; 42 (4): 365–370

Cell-mediated lipoprotein transport: A novel anti-atherogenic concept

Lipoprotein transport is thought to occur in the plasma compartment of the blood, where lipoproteins are modulated by various enzymatic reactions. Subsequently, lipoproteins can migrate through the endothelial barrier to the subendothelial space or are taken up by the liver. The interaction between pro-atherogenic (apoB-containing) lipoproteins and blood cells (especially monocytes and macrophages) in the subendothelial space is well known. This lipoprotein-inflammatory cell interplay is central in the development of the atherosclerotic plaque. In this review, a novel interaction is described between lipoproteins and both leukocytes and erythrocytes in the blood compartment. This lipoprotein-blood cell interaction may also be related to the process of atherosclerosis by inducing inflammatory changes in the case of leukocytes (pro-atherogenic) and as an anti-atherogenic transport-system by adherence to erythrocytes. Triglyceride rich lipoprotein (TRL)-mediated leukocyte activation can lead to an inflammatory situation with generation of oxidative stress and the production of cytokines, ultimately resulting in acute endothelial dysfunction. Binding of apoB containing lipoproteins to erythrocytes may be a potential anti-atherogenic mechanism protecting the vessel wall from the pro-inflammatory effects of these lipoproteins and also playing a role in the removal of these particles from the circulation. One of the proposed mechanisms of this interaction implies complement activation on the lipoprotein surface and binding to the Complement Receptor 1 (CR1) on erythrocytes and leukocytes, followed by clearance by the liver.

Increased incidence of infective endocarditis after the 2009 European Society of Cardiology guideline update: a nationwide study in the Netherlands

Aims After the introduction of the European Society of Cardiology (ESC) guidelines on prevention, diagnosis, and treatment of infective endocarditis (IE) in 2009, prophylaxis for patients at risk became less strict. We hypothesize that there will be a rise in IE after the introduction of the guideline update. Methods and Results We performed a nationwide retrospective trend study using segmented regression analysis of the interrupted time series. The patient data were obtained via the national healthcare insurance database, which collects all the diagnoses nationwide. We compared the data before and after the introduction of the 2009 ESC guideline. Between 2005 and 2011, a total of 5213 patients were hospitalized with IE in the Netherlands. During this period, there was a significant increase in IE from 30.2 new cases per 1 000 000 in 2005 to 62.9 cases per 1 000 000 in 2011 (P < 0.001). In 2009, the incidence of IE increased significantly above the projected historical trend (rate ratio: 1.327, 95% CI: 1.205-1.462; P < 0.001). This coincides with the introduction of the 2009 ESC guideline. After the introduction of the ESC guideline, the streptococci-positive cultures increased significantly in the following years 2010-11 from 31.1 to 53.2% (P = 0.0031). Conclusion This observational study shows that there has been a steady increase in the IE incidence between 2005 and 2011. After the introduction of the 2009 ESC guidelines, the incidence increased more than expected from previous historical trends. Furthermore, there was a significant increase in streptococci-related IE cases.

Trans-vessel gradient of myeloperoxidase in coronary artery disease

Coronary artery disease (CAD) may reflect generalized inflammation. We evaluated leucocyte activation in subjects with and without CAD in different vascular compartments.