Protective roles of HDL, apoA-I and mimetic peptide on endothelial function: Through endothelial cells and endothelial progenitor cells

An association of low high-density lipoprotein levels with recurrence of chronic subdural hematoma

BACKGROUND

Chronic subdural hematoma (CSDH) is a common illness in neurosurgical practice with a substantial recurrence rate. Previous studies found that serum lipids were associated with the risk of stroke and subarachnoid hemorrhage. In the current study, we aimed to identify the relationship between serum lipids and CSDH recurrence.

METHODS

The medical records of 274 consecutive surgical patients with CSDH in our department were reviewed and analyzed. Patients were separated into recurrence and non-recurrence groups. Univariable and multivariable Cox proportional hazards regression analyses were performed to identify serum lipids (triglycerides, total cholesterol, LDL, HDL) and other potential predictors associated with CSDH recurrence, and the performance of predictors was assessed with receiver operating characteristic (ROC) curve.

RESULTS

Of the 274 patients included in the study, 42 (15.3%) experienced at least 1 recurrence of CSDH. Univariate analysis showed that age, hypertension, diabetes mellitus, anticoagulant use, triglycerides, HDL, and midline shift were all significantly associated with CSDH recurrence. Multivariable Cox regression analysis found that only age, diabetes mellitus, midline shift, and HDL level were independent risk factors for CSDH recurrence. A higher HDL level (HR = 0.929, 95% CI 0.905-0.953) was significantly associated with a lower risk of recurrence, and ROC curve analysis revealed that the optimal HDL cut-off value as a predictor was 37.45 mg/dl.

CONCLUSIONS

Low level of high-density lipoprotein is significantly associated with recurrence of chronic subdural hematoma.

Lower or higher HDL-C levels are associated with cardiovascular events in the general population in rural China

BACKGROUND

The present study aims to estimate whether high-density lipoprotein cholesterol (HDL-C) is correlated with cardiovascular events (CVEs) and cardiovascular mortality (CVM) in a large sample of the general population in rural areas of China.

METHODS

Adult participants (n = 10,266, age = 53.79 ± 10.49 years; 46.5% men) were enrolled from the Northeast China Rural Cardiovascular Health Study (NCRCHS). Laboratory testing, blood pressure, weight, height, and questionnaires about socioeconomic status were collected.

RESULTS

In all, 585 nonfatal or fatal CVEs and 212 cardiovascular deaths were documented during a 4.66-year follow-up. Compared to the reference groups (HDL-C between 1.5 and 1.99 mmol/L), either lower or higher levels of HDL-C were correlated with an increased incidence of CVEs but not CVM [hazard ratio (HR) _{the lowest} = 1.369, 95% confidence interval, 1.007-1.861; HR _{the highest} = 1.044, 0.509-2.231]. Elevated CVM was seen in the lowest HDL-C category (1.840; 1.121-3.021).

CONCLUSIONS

Lower or higher HDL-C was associated with a higher incidence of CVEs but not CVM in the general population of rural China. Perhaps if an appropriate level of HDL-C is maintained, CVEs can be effectively prevented.

Potential Medication Treatment According to Pathological Mechanisms in Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a vascular disease with high mortality. Because of the lack of effective medications to stop or reverse the progression of AAA, surgical operation has become the most predominant recommendation of treatment for patients. There are many potential mechanisms, including inflammation, smooth muscle cell apoptosis, extracellular matrix degradation, oxidative stress, and so on, involving in AAA pathogenesis. According to those mechanisms, some potential therapeutic drugs have been proposed and tested in animal models and even in clinical trials. This review focuses on recent advances in both pathogenic mechanisms and potential pharmacologic therapies of AAA.

Influence of high density lipoprotein cholesterol levels on circulating monocytic angiogenic cells functions in individuals with type 2 diabetes mellitus

Background

High-density lipoproteins (HDLs) can exert anti-atherogenic effects. On top of removing excess cholesterol through reverse cholesterol transport, HDLs play beneficial actions on endothelial function and integrity. In particular, HDLs are strong determinant of endothelial progenitor cells (EPCs) number and function. To gain further insights into such an effect we characterized in vitro functionality of circulating “early” EPCs obtained from 60 type 2 diabetes individuals with low HDL-cholesterol (HDL-C) and 59 with high HDL-C levels.

Methods

After an overnight fast, venous blood was drawn in EDTA tubes and processed within 2-h from sampling. Peripheral blood mononuclear cells were isolated and plated on fibronectin coated culture dishes; after 3 days culture, adherent cells positive for Dil-ac-LDL/Lectin dual fluorescent staining were identified as monocytic angiogenic cells (MACs). After 5–7 days culture in EBM-2 medium, adherent cells were evaluated for viability/proliferation (MTT assay), senescence (beta-galactosidase activity detection), migration (modified Boyden chamber using VEGF as chemoattractant), adhesion capacity (on fibronectin-coated culture dishes) and ROS production (ROS-sensitive fluorescent probe CM-H₂DCFDA).

Results

MACs obtained from diabetic individuals with high HDL-C had 23% higher viability compared to low HDL-C (111.6 ± 32.7% vs. 90.5 ± 28.6% optical density; p = 0.002). H₂O₂ exposure impaired MACs viability to a similar extent in both groups (109.2 ± 31.7% vs. 74.5 ± 40.8% in high HDL-C, p < 0.0001; 88.3 ± 25.5% vs. 72.3 ± 22.5% in low-HDL, p = 0.004). MACs senescence was comparable in the two groups (102.7 ± 29.8% vs. 99.2 ± 27.8%; p = 0.703) and was only slightly modified by exposure to H₂O₂. There was no difference in the MACs migration capacity between the two groups (91.3 ± 34.2% vs. 108.7 ± 39.5%; p = 0.111), as well as in MACs adhesion capacity (105.2 ± 32.7% vs. 94.1 ± 26.1%; p = 0.223). Finally, ROS production was slightly thought not significantly higher in MACs from type 2 diabetes individuals with low- than high-HDL. After stratification of HDL-C levels into quartiles, viability (p < 0.0001) and adhesion (p = 0.044) were higher in Q4 than in Q1–Q3. In logistic regression analysis, HDL-C was correlated to MACs viability and adhesion independently of HbA1c or BMI, respectively.

Conclusions

Our data suggest that in type 2 diabetes subjects, HDL-cholesterol is an independent determinant of circulating MACs functional capacities—mainly viability, to a lesser extent adhesion—likely contributing also through this mechanism to cardiovascular protection even in type 2 diabetes.

Effect of anti-ApoA-I antibody-coating of stents on neointima formation in a rabbit balloon-injury model

Background and Aims

Since high-density lipoprotein (HDL) has pro-endothelial and anti-thrombotic effects, a HDL recruiting stent may prevent restenosis. In the present study we address the functional characteristics of an apolipoprotein A-I (ApoA-I) antibody coating in vitro. Subsequently, we tested its biological performance applied on stents in vivo in rabbits.

Materials and Methods

The impact of anti ApoA-I- versus apoB-antibody coated stainless steel discs were evaluated in vitro for endothelial cell adhesion, thrombin generation and platelet adhesion. In vivo, response to injury in the iliac artery of New Zealand white rabbits was used as read out comparing apoA-I-coated versus bare metal stents.

Results

ApoA-I antibody coated metal discs showed increased endothelial cell adhesion and proliferation and decreased thrombin generation and platelet adhesion, compared to control discs. In vivo, no difference was observed between ApoA-I and BMS stents in lumen stenosis (23.3±13.8% versus 23.3±11.3%, p=0.77) or intima surface area (0.81±0.62 mm² vs 0.84±0.55 mm², p=0.85). Immunohistochemistry also revealed no differences in cell proliferation, fibrin deposition, inflammation and endothelialization.

Conclusion

ApoA-I antibody coating has potent pro-endothelial and anti-thrombotic effects in vitro, but failed to enhance stent performance in a balloon injury rabbit model in vivo.

High-density lipoprotein cholesterol raising: does it matter?

PURPOSE OF REVIEW

Cardiovascular disease (CVD) is the leading cause of morbidity and premature mortality in Europe and the United States, and is increasingly common in developing countries. High-density lipoprotein cholesterol (HDL-C) is an independent risk factor for CVD and is superior to low-density lipoprotein cholesterol (LDL-C) as a predictor of cardiovascular events. The residual risk conferred by low HDL-C in patients with a satisfactory LDL-C was recently highlighted by the European Atherosclerosis Society. Despite the lack of randomized controlled trials, it has been suggested that raising the level of HDL-C should be considered as a therapeutic strategy in high-risk patients because of the strong epidemiological evidence, compelling biological plausibility, and both experimental and clinical research supporting its cardioprotective effects.

RECENT FINDINGS

Three recent large randomized clinical trials investigating the effect of HDL-C raising with niacin and dalcetrapib in statin-treated patients failed to demonstrate an improvement in cardiovascular outcomes.

SUMMARY

There is evidence to support the view that HDL functionality and the mechanism by which a therapeutic agent raises HDL-C are more important than plasma HDL-C levels. Future therapeutic agents will be required to improve this functionality rather than simply raising the cholesterol cargo.

Superior in vivo compatibility of hydrophilic polymer coated prosthetic vascular grafts

PURPOSE

Protein adsorption, cell adhesion and graft patency was compared in hydrophilic versus hydrophobic polymer-coated prosthetic vascular grafts. We hypothesize that in vivo compatibility of hydrophilic polymer-coated prosthetic vascular grafts is superior to in vivo compatibility of hydrophobic grafts.

METHODS

A pairwise side-to-side common carotid artery interposition graft was placed eight female landrace goats (mean weight 55 kg). Protein adsorption was assessed using Western Blot in two hydrophilic and two hydrophobic grafts harvested after three days. Graft patency was monitored for 28 days in six goats with continuous wave Doppler ultrasonography. Adherence of endothelial cells, leukocytes and platelets was determined with ELISA and compared between the two graft types after 28 days.

RESULTS

After three days, more ApoA-I, albumin and VEGF and less fibrin adsorbed to hydrophilic grafts. After 28 days, compared to hydrophobic grafts, higher numbers of endothelial cells were present on hydrophilic grafts (P=0.016), and less thrombocytes and leukocytes (P=0.012 and 0.024, respectively). Two out of eight hydrophobic grafts lost patency, while none of the hydrophilic grafts failed (P=0.157).

CONCLUSIONS

Hydrophilic polymer-coated vascular grafts have superior in vivo compatibility when compared to hydrophobic grafts as characterized by reduced platelet and leukocyte adherence as well as higher endothelialization.

Evolving concepts on benefits and risks associated with therapeutic strategies to raise HDL

PURPOSE OF REVIEW

To provide an update on high-density lipoprotein (HDL) biology and emerging new HDL-based therapies for athero-thrombosis.

RECENT FINDINGS

Atherosclerotic cardiovascular disease remains a major public health threat despite a significant decline over the past three decades. Although current medical therapies, specifically low-density lipoprotein lowering with statins, reduce cardiovascular events by about 25-35%, a substantial residual risk remains, leading to a search for additional therapeutic interventions. In this regard, HDL has emerged as one important target because of epidemiologic evidence linking HDL levels inversely to cardiovascular events, known vascular protective actions of HDL and experimental and clinical research supporting athero-protective actions of HDL. However, complexities of HDL composition, particle size, and metabolism have suggested that HDL functionality, and how HDL is increased, may be important determinants of its protective effects.

SUMMARY

Thus the possibility that HDL modification could address the residual risk has brought renewed focus on an old HDL-raising drug, niacin, and a number of newer strategies to exploit the vascular benefits of HDL.

Emerging biology of vascular wall progenitor cells in health and disease

New blood vessels are formed through angiogenesis and postnatal vasculogenesis. Thus, it is essential to identify vascular stem and progenitor cell niches and the mechanisms governing their role in blood vessel formation. Although much is known about circulating and bone marrow-derived endothelial progenitor cells (EPCs), little is known about the vascular wall as an EPC niche. Experimental evidence strongly suggests that EPCs, as well as other stem and progenitor cells, reside in distinct zones of the vessel wall, such as within the subendothelial space and in the so-called "vasculogenic zone" within the vascular adventitia. In this review, we discuss the potential implications of different types of vascular wall resident stem and progenitor cells in health and disease.