Abstract 19325: Genetic Ablation of the P2y2 Nucleotide Receptor Reduces Atherosclerosis in Mice
Objective: We have shown that nucleotide binding to P2Y2 receptor induces endothelial activation via enhanced VCAM-1 expression leading to intimal recruitment of monocyte/macrophage. Here, we sought to determine whether genetic ablation of P2Y2 receptor affects the development of atherosclerosis.
Methods and Results: Western blot and immumofluorescence analysis revealed that P2Y2 receptor deficiency in ApoE mice is accompanied by a sharp reduction in basal VCAM-1 expression levels. To analyze the consequence of P2Y2 receptor deficiency in endothelial function, we examined transmigration of monocytes isolated from the peripheral blood of wt or P2Y2R−/− mice across wt or P2Y2R−/− endothelial monolayers in response to monocyte chemoattractant protein-1. Absence of P2Y2R in endothelial cells significantly impaired monocyte transmigration. Remarkably, loss of P2Y2 receptor in monocytes did not significantly impair transmigration in the presence (transendothelial) or absence (chemotaxis) of P2Y2R+/+ endothelial monolayers, suggesting that endothelial P2Y2R is relatively more important than monocytic P2Y2R in regulating monocyte motility. The absence of P2Y2R did not significantly change the plasma cholesterol or triglyceride levels; however, lipid deposition in the lesion, as demonstrated by Oil Red O–positive region, was decreased by 47% in the aortic preparation from ApoE−/−/P2Y2R+/+mice. Notably, P2Y2R deficiency in ApoE−/− resulted in a 52% reduction in the area of aortic sinus lesion as compared to ApoE−/− mice. Consistent with reduced lesion size, decreased macrophage content was observed in the sinus aortic lesions of ApoE−/−/P2Y2R−/− mice. Staining for SMC showed that most of the SMCs were in the intimal area close to the lumen. The staining showed a 36% decrease in ApoE−/−/P2Y2R−/− when compared with ApoE−/−/P2Y2R+/+ mice. Staining with Sirius red showed that the interstitial collagen content of the lesions of ApoE−/−/P2Y2R+/+ mice was 2-fold higher than in ApoE−/−/P2Y2R−/−mice.
Conclusion: These observations suggest that genetic ablation of P2Y2Rsignificantly decreases both macrophage accumulation and interstitial fibrosis but also reduces smooth muscle cell content of sinus aortic lesions.
- © 2012 by American Heart Association, Inc.