Faculty Bibliography

Resveratrol is a bioactive molecule used in dietary supplements and herbal medicines and consumed worldwide. Known cardioprotective and anti-inflammatory properties of resveratrol have spurred investigation of the mechanisms involved. The present study explored potential atheroprotective actions of resveratrol on cholesterol metabolism in cells of the arterial wall, including human macrophages and arterial endothelium. Using QRT-PCR and Western blotting techniques, we measured expression of the proteins involved in reverse cholesterol transport (ABCA1, ABCG1 and SR-B1) and the scavenger receptors responsible for uptake of modified cholesterol (CD36, SR-A1 and LOX-1). We analyzed the effect of resveratrol on apoA-1-and HDL-mediated cholesterol efflux in human THP-1 macrophages. The effect of resveratrol on oxLDL internalization and foam cell formation were evaluated using confocal and light microscopy. Our data indicate that resveratrol regulates expression of major proteins involved in cholesterol transport, promotes apoA-1 and HDL-mediated efflux, downregulates oxLDL uptake and diminishes foam cell formation. Mechanistically, resveratrol effects were dependent upon PPAR-gamma and adenosine 2A receptor pathways. For the first time we demonstrate that resveratrol regulates expression of the cholesterol metabolizing enzyme cytochrome P450 27-hydroxylase, providing efficient cholesterol elimination via formation of oxysterols. This study establishes that resveratrol attenuates lipid accumulation in cultured human macrophages via effects on cholesterol transport. Further in vivo studies are needed to determine whether resveratrol may be an additional resource available to reduce lipid deposition and atherosclerosis in humans.

The adenosine A(2A) receptor (A(2A)R) plays an important role in the regulation of inflammatory and immune responses. Our previous work has demonstrated that A(2A)R agonists exhibit atheroprotective effects by increasing expression of reverse cholesterol transport proteins in cultured human macrophages. This study explores the impact of pharmacologic activation/inhibition and gene silencing of A(2A)R on cholesterol homeostasis in both THP-1 human monocytes/macrophages and primary human aortic endothelial cells (HAEC). THP-1 human monocytes/macrophages and HAEC exposed to the A(2A)R-specific agonist ATL313 exhibited upregulation of proteins responsible for cholesterol efflux: the ABCA1 and G1 transporters. Further, activation of A(2A)R led to upregulation of the cholesterol metabolizing enzyme P450 27-hydroxylase, accompanied by intracellular changes in level of oxysterols. We demonstrate that anti-atherogenic properties of A(2A)R activation are not limited to the regulation of lipid efflux in vasculature, but include protection from lipid overload in macrophages, particularly via suppression of the CD36 scavenger receptor. The reduced lipid accumulation manifests directly as a diminution in foam cell transformation. In THP-1 macrophages, either A(2A)R pharmacological blockade or gene silencing promote lipid accumulation and enhance foam cell transformation. Our pre-clinical data provides evidence suggesting that A(2A)R stimulation by ATL313 has the potential to be a viable therapeutic strategy for cardiovascular disease prevention, particularly in patients with elevated risk due to immune/inflammatory disorders.

Immunologic derangements in rheumatoid arthritis (RA) patients likely contribute to premature atherosclerotic cardiovascular disease (CVD). Traditional CVD risk factors do not reliably identify at-risk RA patients, probably because disease-associated mechanisms are not taken into account. The purpose of this study was to determine whether plasma from subjects with RA exhibits atheroma-promoting properties leading to disruption of cholesterol homeostasis in human monocytes/macrophages. Twenty-one healthy controls (HC) and 22 RA patients were enrolled in an IRB approved study at Winthrop University Hospital. Naive THP-1 macrophages were exposed to plasma from each HC and RA patient. Following incubation, RNA and protein were isolated. QRT-PCR and Western blotting techniques were then used to measure expression of proteins responsible for cholesterol efflux (ATP binding cassette transporter (ABC)A1, ABCG1, 27-hydroxylase) and cholesterol uptake (CD36, ScR-A1, lectin oxidized low density lipoprotein receptor (LOX)-1, CXCL16). To confirm the pro-atherogenic effects of RA plasma on macrophages, foam cell formation was quantified. Results showed that RA plasma downregulates cholesterol efflux proteins and upregulates scavenger receptors CD36, LOX1 and CXCL16. These pro-atherogenic changes in gene expression in the presence of RA plasma are associated with augmented lipid accumulation and foam cell formation by THP-1 macrophages. RA plasma induces macrophage cholesterol overload. Demonstration of disrupted cholesterol homeostasis mediated by RA plasma provides further evidence of the involvement of the immune system in atherogenesis. Our data suggest that chronic exposure to RA plasma adversely affects the capacity of monocytes/macrophages in the arterial wall to metabolize cholesterol and maintain lipid homeostasis, thereby contributing to the development of premature atherosclerosis.

OBJECTIVE:To investigate the occurrence, clinical correlates, and immunohistochemical phenotype of temporal small-vessel inflammation (TSVI) in temporal artery biopsies from patients presenting with clinical features of giant cell arteritis (GCA). METHODS:We retrospectively reviewed 41 temporal artery biopsy specimens for the presence of inflammatory infiltrates in small vessels external to the temporal artery adventitia (TSVI); 33 had sufficient clinical and pathological data for detailed analysis. Clinical and laboratory features at presentation and corticosteroid treatment patterns of patients with isolated TSVI were compared to those of patients with positive and negative biopsies. The cellular composition of the infiltrates was further characterized by immunohistochemistry. RESULTS:Twenty-three (70%) specimens had evidence of TSVI including 10 with concurrent GCA and 13 (39%) with isolated TSVI. TSVI was found in all positive temporal artery biopsies. The proportion of macrophages and of lymphocyte subpopulations differed between infiltrates observed in TSVI and those of the main temporal artery wall. Initial erythrocyte sedimentation rate (ESR) was similar in the TSVI and positive biopsy groups and was significantly higher than in the negative biopsy group. Patients with isolated TSVI more often had symptoms of polymyalgia rheumatica compared to the positive biopsy group. Patients with TSVI received corticosteroid doses that were intermediate between patients with positive and those with negative biopsies. CONCLUSION/CONCLUSIONS:A significant number of patients with clinical features of GCA demonstrated isolated TSVI. Differences in the clinical presentation and cellular composition suggest that TSVI may represent a subset of GCA and should be considered in the interpretation of temporal artery biopsies and treatment decisions.