P2Y receptors and atherosclerosis in apolipoprotein E-deficient mice.
OBJECTIVE
P2Y nucleotide receptors are involved in the regulation of vascular tone, smooth muscle cell (SMC) proliferation and inflammatory responses. The present study investigated whether they are involved in atherosclerosis.


METHODS
mRNA of P2Y receptors was quantified (RT-PCR) in atherosclerotic and plaque-free aorta segments of apolipoprotein E-deficient (apoE(-/-)) mice. Macrophage activation was assessed in J774 macrophages, and effects of non-selective purinoceptor antagonists on atherosclerosis were evaluated in cholesterol-fed apoE(-/-) mice.


RESULTS
P2Y(6) receptor mRNA was consistently elevated in segments with atherosclerosis, whereas P2Y(2) receptor expression remained unchanged. Expression of P2Y(1) or P2Y(4) receptor mRNA was low or undetectable, and not influenced by atherosclerosis. P2Y(6) mRNA expression was higher in cultured J774 macrophages than in cultured aortic SMCs. Furthermore, immunohistochemical staining of plaques demonstrated P2Y(6)-positive macrophages, but few SMCs, suggesting that macrophage recruitment accounted for the increase in P2Y(6) receptor mRNA during atherosclerosis. In contrast to ATP, the P2Y(6)-selective agonist UDP increased mRNA expression and activity of inducible nitric oxide synthase and interleukin-6 in J774 macrophages; this effect was blocked by suramin (100-300 microM) or pyridoxal-phosphate-6-azophenyl-2'-4'-disulphonic acid (PPADS, 10-30 microM). Finally, 4-week treatment of cholesterol-fed apoE(-/-) mice with suramin or PPADS (50 and 25 mg.kg(-1).day(-1) respectively) reduced plaque size, without changing plaque composition (relative SMC and macrophage content) or cell replication.


CONCLUSIONS
These results suggest involvement of nucleotide receptors, particularly P2Y(6) receptors, during atherosclerosis, and warrant further research with selective purinoceptor antagonists or P2Y(6) receptor-deficient mice.
Guns
Pieter-Jan D F
PJ
Division of Pharmacology, University of Antwerp, Wilrijk, Belgium. pieter-jan.guns@ua.ac.be
Hendrickx
Jan
J
Van Assche
Tim
T
Fransen
Paul
P
Bult
Hidde
H
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D001057:Apolipoproteins E / Q000235:genetics*; D050197:Atherosclerosis / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D002460:Cell Line; D015850:Interleukin-6 / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D018048:Receptors, Purinergic P2 / Q000096:biosynthesis*; D013498:Suramin / Q000494:pharmacology; D014530:Uridine Diphosphate / Q000494:pharmacology
D001057:Apolipoproteins E; D015850:Interleukin-6; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; C099845:purinoceptor P2Y6; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D014530:Uridine Diphosphate; D011732:Pyridoxal Phosphate; D013498:Suramin; D052247:Nitric Oxide Synthase Type II