Abstract 295: Intra-Plaque Hemorrhage Is Associated With Decreased Content of Macrophage Scavenger Receptor CD-163 in Diabetic Atherosclerosis.
Background: The major defense mechanism against intra-plaque hemorrhage (IPH) is mediated by the haptoglobin/hemoglobin macrophage scavenger receptor CD-163. Stimulation of CD-163 results in the release of anti-inflammatory cytokines, which may reduce the deleterious effects of IPH. Down-regulation of this receptor may contribute to the higher prevalence of IPH in diabetic when compared to non-diabetic plaques. This study was designed to test the hypothesis that IPH is associated with decreased content of macrophage scavenger receptor CD163 in diabetic when compared to non-diabetic atherosclerotic plaques.
Materials and Methods: Two-hundred and sixty-nine human aortic plaques were screen for IPH. After excluding ruptured plaques, 65 plaques with IPH (49 diabetic and 16 non-diabetic) were immunostained for the macrophage scavenger receptor CD-163. A score system for CD-163 positive cells (0= ≤ 5 cells; 1= 6 –25 cells; and 2= ≥26 cells) was applied in 10 random high-power fields per plaque, both at the fibrous cap/shoulder and at the core of the plaque. This score was then compared between diabetic and non-diabetic plaques.
Results: The average score for CD-163 cell-receptor content was lower in diabetic when compared to non-diabetic plaques both at the fibrous cap/shoulder (P=0.0001) and at the core of the plaque (P=0.0001), as shown in the composite Figure⇓.
Conclusion: Intra-plaque hemorrhage is associated with decreased content of macrophage scavenger receptor CD-163 in diabetic atherosclerosis. These findings may provide a link explaining the stronger correlation of IPH and atherosclerotic plaque instability in patients with diabetes mellitus.