Overexpression of Toll-Like Receptors 2, 3, 4, and 8 Is Correlated to the Vascular Atherosclerotic Process in the Hyperlipidemic Rabbit Model: The Effect of Statin Treatment.

BACKGROUND: Atherosclerosis is the major cause of cardiovascular disease; hypercholesterolemia is a major risk factor. We hypothesized that specific TLR members (TLR2, TLR3, TLR4, TLR8) may play a role in atherosclerosis progression and its accompanying inflammatory response. We determined the association of atherosclerotic lesions and TLR mRNA expression in different aortic sites. We also assessed the effects of fluvastatin (Flu) treatment on TLR expression and plaque characteristics. METHODS: Male rabbits, fed with an atherogenic diet for a duration of 3 months, were screened for advanced atherosclerotic lesions in the aorta. Additional animals received normal diet or normal diet plus Flu for 1 additional month. TLR mRNA expression in various thoracic and abdominal aortic segments was assessed, together with atherosclerotic changes. RESULTS: After high lipid diet, the atherosclerotic burden increased more in the abdominal than in the thoracic aorta; TLR2, 3, 4, and 8 also increased significantly. Flu decreased atherosclerotic plaque, calcium deposition, lipid cores, intraplaque hemorrhage, erythrocyte membranes, endothelial cells, and macrophage infiltration, while increasing smooth muscle cells in plaques of both aortic segments; it also lowered TLR2, 3, 4, and 8 expression in all aortic segments to a stronger degree than resumption of normal diet. There was a strong association between blood and tissue parameters during experimental period and finally a strong correlation found between these parameters with mRNA of TLR2, 3, 4, and 8 in various stages. CONCLUSION: For the first time TLR2, 3, 4, and 8 mRNA expression is prospectively explored after hypercholesterolemic diet in the rabbit model. TLR2, 3, 4, and 8 mRNA expression is strongly upregulated and correlates with the progression of atherosclerosis in the aorta. Flu significantly inhibited this progress and reduced inflammation via TLR downregulation which was strongly associated with regression of plaque morphology and atherosclerosis promoting factors.

Erythrocyte membrane cholesterol and lipid core growth in a rabbit model of atherosclerosis: modulatory effects of rosuvastatin.

BACKGROUND: Lipid core expansion is partly responsible for the conversion of a stable atherosclerotic lesion to a rupture-prone plaque. Intraplaque hemorrhage contributes to the accumulation of cholesterol within unstable plaques. In the present study, we investigated, using a rabbit model of atherosclerosis, the extent to which diet-induced increases in cholesterol content of erythrocyte membranes (CEM) contribute to lipid core expansion and the modulatory effect of rosuvastatin use. METHODS AND RESULTS: Rabbits fed with atherogenic diet (0.75% cholesterol) for 5 months exhibited advanced atherosclerotic lesions (mean plaque area, 0.39 ± 0.03 mm(2)), and lipid core size was associated with the concentration-time integral (CTI) of CEM levels (r=0.567, P=0.004) independent of other established predictors of lipid core size. Further experiments were performed by feeding rabbits atherogenic diet (1% cholesterol) for 3 months, followed by either normal diet or normal diet plus rosuvastatin for the next 3 months. Although no differences were observed in total plaque area between both groups, administration of rosuvastatin was associated with significantly smaller lipid cores, fewer macrophages within the lipid core, less microvessels as well as with lower CTI of CEM levels compared to normal diet alone. Moreover, intraplaque erythrocyte membranes covered a smaller lipid core area in rabbits under rosuvastatin plus normal diet as opposed to rabbits under diet alone. CONCLUSIONS: Increased CEM levels, induced by high-cholesterol diet, are associated with lipid core growth. Ingestion of a potent HMG-CoA reductase inhibitor (rosuvastatin) may decrease CEM levels, and this effect may contribute to regression of the lipid core.

Gender does not influence angiogenesis and arteriogenesis in a rabbit model of chronic hind limb ischemia.

OBJECTIVE: Estrogen administration promotes angiogenesis and perfusion in oophorectomized rabbits with chronic limb ischemia. In the present study we tested whether gender affects angiogenesis and arteriogenesis in a rabbit model of chronic hind limb ischemia. METHODS AND RESULTS: Ischemia was induced in one hind limb of five oophorectomized (Ooph), seven non-oophorectomized (NonOoph) female and eight male New Zealand White rabbits by excision of the femoral artery. Ten days after the induction of ischemia (day 0) and at days 15 and 30 systolic calf blood pressure was measured in the ischemic and non-ischemic hind limbs. Revascularization in the ischemic limb was expressed as ischemic/normal limb blood pressure, capillary/muscle fiber density, and non-capillary, non-lymphatic vessels/muscle fiber density after examination of light microscopic sections taken from the abductor muscle of the ischemic limb at the time of death (day 30). Ischemic/normal blood pressure at day 30 in males was 0.62 +/- 0.22, in NonOoph 0.64 +/- 0.09 (P=ns vs. males) and in Ooph 0.39 +/- 0.05 (P<0.05 vs. males and NonOoph), (F=4.69, P=0.02). Ischemic capillary/muscle fiber in males was 0.96 +/- 0.09, in NonOoph 0.95 +/- 0.06 (P=ns vs. males) and in Ooph 0.83 +/- 0.09 (P<0.05 vs. males and NonOoph), (F=5.93, P=0.01). Ischemic non-capillary, non-lymphatic vessels/muscle fiber density in males was 0.11 +/- 0.02, in NonOoph 0.12 +/- 0.03 (P=ns vs. males) and in Ooph 0.08 +/- 0.02 (P<0.05 vs. NonOoph), (F=5.05, P=0.02). CONCLUSION: Gender does not influence angiogenesis and arteriogenesis in the rabbit model of chronic hind limb ischemia. However, estrogen deficiency induced by oophorectomy negatively affects angiogenesis and arteriogenesis.