Milita Crisby

Pravastatin Treatment Increases Collagen Content and Decreases Lipid Content, Inflammation, Metalloproteinases, and Cell Death in Human Carotid Plaques Implications for Plaque Stabilization

Background —The clinical benefits of lipid lowering with statins are attributed to changes in plaque composition leading to lesion stability, but supporting clinical data from human studies are lacking. Therefore, we investigated the effect of 3 months of pravastatin treatment on composition of human carotid plaques removed during carotid endarterectomy. Methods and Results —Consecutive patients with symptomatic carotid artery stenosis received 40 mg/d pravastatin (n=11) or no lipid-lowering therapy (n=13; control subjects) for 3 months before scheduled carotid endarterectomy. Carotid plaque composition was assessed with special stains and immunocytochemistry with quantitative image analysis. Plaques from the pravastatin group had less lipid by oil red O staining (8.2±8.4% versus 23.9±21.1% of the plaque area, P <0.05), less oxidized LDL immunoreactivity (13.3±3.6% versus 22.0±6.5%, P <0.001), fewer macrophages (15.0±10.2% versus 25.3±12.5%, P <0.05), fewer T cells (11.2±9.3% versus 24.3±13.4%, P <0.05), less matrix metalloproteinase 2 (MMP-2) immunoreactivity (3.6±3.9% versus 8.4±5.3%, P <0.05), greater tissue inhibitor of metalloproteinase 1 (TIMP-1) immunoreactivity (9.0±6.2% versus 3.1±3.9%, P <0.05), and a higher collagen content by Sirius red staining (12.4±3.1% versus 7.5±3.5%, P <0.005). Cell death by TUNEL staining was reduced in the pravastatin group (17.7±7.8% versus 32.0±12.6%, P <0.05). Conclusions —Pravastatin decreased lipids, lipid oxidation, inflammation, MMP-2, and cell death and increased TIMP-1 and collagen content in human carotid plaques, confirming its plaque-stabilizing effect in humans.

Cell death in human atherosclerotic plaques involves both oncosis and apoptosis

The aim of the present study was to analyze the frequency and mechanism of cell-death in atherosclerotic plaques with a recent history (< 6 months) of rupture. Atherosclerotic plaques were obtained from patients with symptomatic ipsilateral carotid stenosis > 70% diameter reduction undergoing carotid endarterectomy. In situ tailing and nick translation of fragmented DNA, agarose gel electrophoresis of plaque DNA and electron microscopy were used to identify cell death by apoptosis (programmed cell death) and oncosis. The mean number of cells containing fragmented DNA in the plaques was 12.7 +/- 3.5% (n = 15). Focal accumulations of cells with DNA fragmentation occurred in the fibrous cap, at sites of rupture, close to lipid deposits and necrosis and was always accompanied by the presence of inflammatory cells. Electrophoretic separation of DNA isolated from part of plaques, where the presence of DNA fragmentation had previously been demonstrated by in situ DNA nick translation, resulted in multiple ladders of 180-200 base pairs characteristic of apoptosis. Electron microscopic analysis revealed presence of cells with morphological signs of degeneration in a frequency even higher than that found by in situ nick translation. Some of these cells had a characteristic apoptotic appearance with condensed chromatin and cytoplasm, but the large majority of the cells had an ultrastructure typical for cells undergoing cell death by oncosis with membrane disruption and swollen, disintegrating organelles. Thus, although apoptosis clearly takes place in atherosclerotic plaques, oncosis appears to be a much more common mechanism for cell death.

Plasma levels of 24S-hydroxycholesterol in patients with neurological diseases.

The brain is the exclusive or almost exclusive site of formation of 24S-hydroxycholesterol and we have shown that the circulating level of 24S-hydroxycholesterol is dependent upon the relation between cerebral production and hepatic clearance. In the present work we determined plasma levels of 24S-hydroxycholesterol in patients with various neurological diseases. Eleven subjects with brain death occurring 6-10 h before collection of the plasma samples had markedly reduced circulating levels of 24S-hydroxycholesterol (-43%, P<0.001). Patients with advanced Alzheimers disease and cerebral inflammatory diseases had slightly lower levels of 24S-hydroxycholesterol in plasma when compared to matched controls. Patients with acute ischemic stroke, multiple sclerosis and primary brain tumors had levels not significantly different from those of controls. The conditions leading to reduced plasma levels of 24S-hydroxycholesterol had no significant effect on plasma levels of another side-chain oxidized oxysterol, 27-hydroxycholesterol. Except for conditions characterized by very marked destruction of the central nervous system, different severe neurological diseases seem to have relatively small effects on the flux of 24S-hydroxycholesterol from the brain.

Localization of sterol 27-hydroxylase immuno-reactivity in human atherosclerotic plaques

It has recently been shown that extrahepatic cells can eliminate intracellular cholesterol by enzymatic conversion into 27-hydroxy-cholesterol and 3 beta-hydroxy-5-cholestenoic acid. Using immunohistochemical methods, we studied the presence of the enzyme responsible for these conversions, sterol 27-hydroxylase, in human carotid atherosclerotic plaques. All plaques examined were found to contain sterol 27-hydroxylase immuno-reactive cells. While some endothelial cells stained for sterol 27-hydroxylase, the majority of the immunoreactive cells co-localized with macrophages. Accumulation of sterol 27-hydroxylase-positive cells were often observed in macrophage-rich core regions of complicated lesions. High concentrations of 27-hydroxycholesterol were found in plaques, while the concentration in non-atherosclerotic human vessels was lower by two orders of magnitude. The rabbit, which is particularly sensitive to dietary cholesterol and easily develops fatty streaks, had low plasma levels of 27-hydroxycholesterol, 3 ng/ml compared to 150 ng/ml in humans. The concentration of 27-hydroxycholesterol in the atherosclerotic rabbit vessels was also lower compared to human atherosclerotic plaques. The results are consistent with our hypothesis that sterol 27-hydroxylase may be utilized by human macrophages as a defence towards a high cholesterol load. This mechanism may be less important in some other species.

Urinary complaints in nondisabled elderly people with age-related white matter changes: the Leukoaraiosis And DISability (LADIS) Study.

OBJECTIVES: To investigate, in a cohort of nondisabled elderly people, the association between urinary complaints and severity of age‐related white matter changes (ARWMC).

DNA Fragmentation and Ultrastructural Changes of Degenerating Cells in Atherosclerotic Lesions and Smooth Muscle Cells Exposed to Oxidized LDL in Vitro

Degeneration of smooth muscle cells in the fibrous cap of atherosclerotic lesions is an important factor in plaque rupture. Recent studies have suggested that many plaque cells are in a process of apoptosis as determined by positive deoxyribonucleotide-transferase-mediated dUTP end labeling. In this study, we demonstrate the existence of a colocalization between deoxyribonucleotide-transferase-mediated dUTP end labeling-positive smooth muscle cells and oxidized LDL immunoreactivity in human carotid plaques. Oxidized LDL was found to induce deoxyribonucleotide-transferase-mediated dUTP end labeling positivity in cultured human smooth muscle cells, but only in the presence of tumor necrosis factor-alpha and interferon-gamma. Electron microscopic analysis of cultured smooth muscle cells exposed to oxidized LDL in the absence of cytokines demonstrated cytoplasmic swelling and disruption of the plasma membrane, suggesting cell death by oncosis. Cells exposed to both oxidized LDL and cytokines were characterized by chromatin and cytoplasmic condensation compatible with cell death by apoptosis. These findings further support the notion that oxidized lipids play a role in plaque cell death.

Adiponectin and Carotid Intima-Media Thickness in the Northern Manhattan Study

Background and Purpose— Adiponectin is an insulin-sensitizing plasma protein expressed in adipose tissue and suggested to play a role in atherosclerosis and cardiovascular disease. Data are lacking on the relationship between adiponectin and carotid intima-media thickness (IMT) in ethnically heterogeneous populations. We examined the relationship between adiponectin and IMT, a marker of atherosclerosis, in a multiethnic cohort study of stroke risk factors. Methods— Participants were from the Northern Manhattan Study (N=1522, mean age 66±9 years, 60% female, 20% black, 18% white, 60% Hispanic). Adiponectin was measured from baseline plasma samples and IMT was assessed by high-resolution B-mode carotid ultrasound. Regression models were used to examine the association between adiponectin, assessed continuously and in quartiles, and IMT controlling for demographics and vascular risk factors. Results— The mean adiponectin level was 10.3±5.2 &mgr;g/mL (median, 9.2 &mgr;g/mL; range, 2.3–53.3 &mgr;g/mL), and the mean IMT was 0.91±0.08 mm. Adiponectin was inversely associated with IMT, even after controlling for demographics and vascular risk factors. Individuals in the first quartile of adiponectin had mean IMT that was on average 0.02 mm greater than those in the top quartile. The relationship between adiponectin and IMT appeared to be stronger among those with diabetes. Conclusions— Our findings suggest that low adiponectin is associated with increased IMT in a multiethnic cohort and support a protective role for adiponectin in atherosclerosis.

An angiotensin‐converting enzyme gene polymorphism suggests a genetic distinction between ischaemic stroke and carotid stenosis

Ischaemic cerebrovascular disease (ICVD) is a heterogeneous syndrome to which different genetic factors may contribute. We have investigated the distribution of alleles of the angiotensin‐converting enzyme (ACE) gene, which has been suggested to be of possible importance in ischaemic stroke or cardiovascular disease, in groups of patients with ischaemic stroke and carotid artery stenosis (CS).

Lipoprotein lipase gene polymorphisms in ischaemic stroke and carotid stenosis

Ischaemic stroke is pathogenetically heterogeneous, but there is strong evidence that genetic as well as environment factors contribute to the risk of the individual. Here we report the similar distribution of polymorphic markers of the lipoprotein lipase (LPL) gene in 128 patients with ischaemic stroke, 56 patients with carotid artery stenosis and 95 healthy control subjects, in spite of a significant influence of the Asn291→ Ser mutation on serum levels of triglycerides. We conclude that these LPL polymorphisms do not contribute greatly to the overall risk of ischaemic stroke in the general population.

Effects of statins on α7 nicotinic receptor, cholinesterase and α-form of secreted amyloid precursor peptide in SH-SY5Y cells

In order to reveal the neuroprotective effects of statins that could be of interest for the prevention and treatment of Alzheimers disease (AD), we investigated the expression of nicotinic acetylcholine receptors (nAChRs) detected by RT-PCR, the activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) by colorimetric determination, and the levels of the alpha-form of secreted beta-amyloid precursor protein (alphaAPPs) by Western blotting in neuroblastoma (SH-SY5Y) cells exposed to lovastatin, atorvastatin, rosuvastatin and simvastatin, respectively. The results indicated that all statins studied, both lipophilic and hydrophilic, induced high expression of alpha7 nAChR, decreased cholinesterase activities, and increased alphaAPPs, which suggests that statins might play important neuroprotective roles in AD treatment.