Interleukin-10 expression is positively correlated with oxidized LDL deposition and inversely with T-lymphocyte infiltration in atherosclerotic intimas of human coronary arteries

The inflammatory balance modulated by pro- and anti-inflammatory cytokines in atherosclerotic lesions is still unclear. The purpose of this study was to investigate the immunohistochemical localization of interleukin-10 (IL-10) and the topographical correlation between IL-10-positive cells and the other inflammatory cells in human coronary arteries. Coronary arteries (242 sections) were obtained from 43 Japanese patients (mean age: 72±14 years) at autopsy, and the intimal changes were classified according to the classification of the American Heart Association. The immunohistochemical distributions of IL-10, oxidized low-density lipoprotein (oxLDL), macrophages, and lymphocytes were examined morphometrically. We compared the ratios of IL-10-positive cells/macrophages and T-lymphocyte number among the shoulder and in other areas of type IV lesions and in atherosclerotic lesion types. IL-10 was expressed mainly by macrophages, and the positive cell number increased as the lesions became advanced (p<0.0001). The number of IL-10-positive cells was positively correlated with that of oxLDL-positive cells, and inversely with infiltrating T-lymphocytes (p<0.01). IL-10 expression in type IV-plaque shoulder was significantly lower than that in fibrous cap and the deeper portion under necrotic core (p<0.01). These findings suggest that IL-10 expression, seen mainly in macrophages, was possibly upregulated with oxLDL, and was inversely correlated with T-lymphocytic function in atherosclerotic coronary intimas.