RESUMO
Atherosclerosis is an inflammatory disease that leads to an aberrant accumulation of cholesterol in vessel walls forming atherosclerotic plaques. During this process, the mechanism regulating complex cellular cholesterol pools defined as the reverse cholesterol transport (RCT) is altered as well as expression and functionality of transporters involved in this process, namely ABCA1, ABCG1, and SR-BI. Macrophages, arterial endothelial and smooth muscle cells (SMCs) have been involved in the atherosclerotic plaque formation. As macrophages are widely described as the major cell type forming the foam cells by accumulating intracellular cholesterol, RCT alterations have been poorly studied at the arterial endothelial cell and SMC levels. Amongst the therapeutics tested to actively counteract cellular cholesterol accumulation, the methylated ß-cyclodextrin, KLEPTOSE® CRYSMEß, has recently shown promising effects on decreasing the atherosclerotic plaque size in atherosclerotic mouse models. Therefore we investigated in vitro the RCT process occurring in SMCs and in arterial endothelial cells (ABAE) as well as the ability of some modified ß-CDs with different methylation degree to modify RCT in these cells. To this aim, cells were incubated in the presence of different methylated ß-CDs, including KLEPTOSE® CRYSMEß. Both cell types were shown to express basal levels of ABCA1 and SR-BI whereas ABCG1 was solely found in ABAE. Upon CD treatments, the percentage of membrane-extracted cholesterol correlated to the methylation degree of the CDs independently of the lipid composition of the cell membranes. Decreasing the cellular cholesterol content with CDs led to reduce the expression levels of ABCA1 and ABCG1. In addition, the cholesterol efflux to ApoA-I and HDL particles was significantly decreased suggesting that cells forming the blood vessel wall are able to counteract the CD-induced loss of cholesterol. Taken together, our observations suggest that methylated ß-CDs can significantly reduce the cellular cholesterol content of cells forming atherosclerotic lesions and can subsequently modulate the expression of ABC transporters involved in RCT. The use of methylated ß-CDs would represent a valuable and efficient tool to interfere with atherosclerosis pathogenesis in patients, nonetheless their mode of action still needs further investigations to be fully understood and finely controlled at the cellular level.
RESUMO
The ability of pharmacological agents to target both "classical" risk factors and inflammation may be key for successful outcomes in the prevention and treatment of atherogenesis. Among the promising drugs interfering with cholesterol metabolism, we investigated whether methyl beta-cyclodextrin (KLEPTOSE® CRYSMEB) could positively impact on atherogenesis, lipid profile and atherosclerotic plaque inflammation in ApoE-/- mice. Eleven-week old ApoE-/- mice were fed either a normal diet (N.D.) or a high-cholesterol diet (H.D.), resulting in different levels of hypercholesterolemia. KLEPTOSE® CRYSMEB (40mg/kg) or vehicle was intraperitoneally administrated 3 times per week in the last 16weeks before euthanasia in mice under N.D. and in the last 11weeks under H.D. Treatment with KLEPTOSE® CRYSMEB reduced triglyceride serum levels in both atherogenesis mouse models. In H.D. mice, treatment with KLEPTOSE® CRYSMEB increased HDL-cholesterol levels and reduced free fatty acids and spleen weight. In both mouse models, treatment with KLEPTOSE® CRYSMEB reduced atherosclerotic plaque size in thoraco-abdominal aortas and intraplaque T lymphocyte content, but did not induce relevant improvements in other histological parameters of vulnerability (macrophage, neutrophil, MMP-9 and collagen content). Conversely and more markedly in H.D. mice, treatment with KLEPTOSE® CRYSMEB was associated with a reduction in genetic markers of Th1-mediated immune response. In vitro, KLEPTOSE® CRYSMEB dose-dependently abrogated Th1 proliferation and IFNγ release. In conclusion, treatment with KLEPTOSE® CRYSMEB reduced atherosclerotic plaque size by improving triglyceride serum levels and Th1-mediated response. These results indicate this drug as a potential tool for blocking atheroprogression associated with different severity degrees of hypercholesterolemia.
