Expression of Apoptotic Markers Bcl-2 and Bax in the Vascular Wall

The aim of the study was to assess the levels of Всl-2 and Bax proteins in the vascular wall and their correlation with serum cholesterol in patients with stage III–IV atherosclerosis obliterans of lower limb arteries. MATERIALS AND METHODS: The study included 32 patients with stage III–IV atherosclerosis obliterans of the lower limb. Samples of intraoperative material (all three layers of the vascular wall) including an atherosclerotic plaque (AP) were taken during primary open surgery on major leg arteries. As a control, we used samples of the arterial wall without visible signs of atherosclerosis. Based on AP ultrasonography, the patients were divided into two groups: with APs of mixed echogenicity and with hyperechoic (calcified) AP. The vascular samples were crushed and homogenized for further measurements of Всl-2 and Bax proteins; in a separate setup, cholesterol in blood serum was measured. RESULTS: In patients without atherosclerotic changes, the level of the anti-apoptotic protein Bcl-2 in the arterial wall was 1.25 ng/mg, and that of the pro-apoptotic protein Bax — 4.7 ng/mg. In the case of APs of mixed echogenicity, the expression of Bcl-2 was 1.8 ng/mg (p=0.143) and that of Bax — 5.1 ng/mg (p=0.834), with no significant differences from AP-free vascular wall samples. In the arterial wall containing a heterogeneous calcified AP, the expression of Bcl-2 was 0.9 ng/mg (p=0.143), In contrast, the level of Bax was 6.8 ng/mg, which showed its significant increase as compared with the non-AP controls (p=0.02). In the cases with predominantly hyperechoic AP, the expression of Bcl-2 was significantly lower (p=0.036), and that of Bax — significantly higher (p=0.036) in comparison with AP of mixed echogenicity. In patients with hyperechoic AP, we found a negative correlation between the Bax and Bcl-2 values ( r=–0.315) and a positive correlation between the Bax expression and serum cholesterol (r=0.617). CONCLUSION: In arterial walls with hyperechoic (calcified) APs, the expression of anti-apoptotic protein Bcl-2 is reduced, and that of pro-apoptotic protein Bax is increased, which indicates the apoptosis activation in advanced atherosclerotic lesions. In patients with such APs, elevated cholesterol levels directly correlate with the increased expression of pro-apoptotic Bax protein (r=0.617).