Selective Alterations of Thiol Redox Homeostasis and Antioxidant Enzyme Activity in Advanced Atherosclerosis.

Atherosclerosis is a progressive vascular disease characterized by lipid-rich plaque accumulation, oxidative stress, and chronic inflammation, contributing to coronary heart disease, stroke, and peripheral arterial disease. This study investigated the impact of inflammation, vascular calcification, and statin therapy on redox balance in blood and carotid artery plaques, aiming to identify potential biomarkers for disease assessment. Thirty-two patients undergoing carotid endarterectomy provided 34 plaque samples. Enzyme activities in plaque/erythrocytes and -SH group concentration in plasma/plaque were measured. Pathological analysis was performed to determine inflammation/calcification grade, the presence of mast cells and plaque composition. The results showed that mast cells were associated with reduced non-protein -SH groups, indicating selective thiol consumption and serving as a qualitative marker of oxidative burden. Reduced catalase activity in erythrocytes was associated with advanced calcification, pointing to long-standing systemic oxidative stress. Statin therapy enhanced systemic superoxide-dismutase 1 activity, increased -SH groups, and modulated plaque-specific glutathione reductase activity, attenuating sex-related differences in redox regulation. These findings highlight the complex interplay between systemic and local oxidative processes in atherosclerosis through alterations in redox-related biomarkers such as plasma -SH group concentrations and catalase activity.