Increased lipoprotein-associated phospholipase A 2 (Lp-PLA 2 ) activity is associated with increased risk of cardiac events, but it is not known whether Lp-PLA 2 is a causative agent. Here we show that selective inhibition of Lp-PLA 2 with darapladib reduced development of advanced coronary atherosclerosis in diabetic and hypercholesterolemic swine. Darapladib markedly inhibited plasma and lesion Lp-PLA 2 activity and reduced lesion lysophosphatidylcholine content. Analysis of coronary gene expression showed that darapladib exerted a general anti-inflammatory action, substantially reducing the expression of 24 genes associated with macrophage and T lymphocyte functioning. Darapladib treatment resulted in a considerable decrease in plaque area and, notably, a markedly reduced necrotic core area and reduced medial destruction, resulting in fewer lesions with an unstable phenotype. These data show that selective inhibition of Lp-PLA 2 inhibits progression to advanced coronary atherosclerotic lesions and confirms a crucial role of vascular inflammation independent from hypercholesterolemia in the development of lesions implicated in the pathogenesis of myocardial infarction and stroke.Atherosclerosis, the most common cause of myocardial infarction, stroke and cardiovascular death, is an inflammatory-immunomodulatory disease 1,2 . A key early step in its development is the accumulation and subsequent oxidation of low-density lipoproteins COMPETING INTERESTS STATEMENTThe authors declare competing financial interests: details accompany the full-text HTML version of the paper at http://www.nature.com/naturemedicine/. Lp-PLA 2 , also known as platelet-activating factor acetylhydrolase or type VIIA PLA 2 , is a calcium-independent phospholipase A 2 . In humans, Lp-PLA 2 is secreted by leukocytes and is associated with circulating LDL and macrophages in atherosclerotic plaques. Although some have hypothesized that Lp-PLA 2 has a protective role in atherosclerotic lesion development 9,10 , the preponderance of recent data suggests that Lp-PLA 2 has an active role in atherosclerotic development and progression [11][12][13] . Elevated circulating Lp-PLA 2 activity predicts increased cardiovascular risk 14 . A proatherogenic role for Lp-PLA 2 has been postulated on the basis of its ability to generate two key proinflammatory mediators, lysophosphatidylcholine (LPC) and oxidized nonesterified fatty acids (oxNEFAs), through the cleavage of oxidized or polar phospholipids generated during LDL oxidation 15,16 . Evidence exists for a regulatory role of these proinflammatory lipids, particularly of LPC 12,13,17 , in promoting atherosclerotic plaque development that can ultimately lead to the formation of a necrotic core. These steps include recruitment and activation of leukocytes 12,18 , induction of apoptosis 12,19 and impaired removal of dead cells 20,21 . The demonstration that Lp-PLA 2 is highly upregulated in macrophages undergoing apoptosis within the necrotic core and fibrous cap of vulnerable and ruptured plaques, ...

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The extracellular signal-regulated kinase (ERK) pathway is activated by hypertrophic stimuli in cardiomyocytes. However, whether ERK plays an essential role or is implicated in all major components of cardiac hypertrophy remains controversial. Using a selective MEK inhibitor, U0126, and a selective Raf inhibitor, SB-386023, to block the ERK signaling pathway at two different levels and adenovirus-mediated transfection of dominant-negative Raf, we studied the role of ERK signaling in response of cultured rat cardiomyocytes to hypertrophic agonists, endothelin-1 (ET-1), and phenylephrine (PE). U0126 and SB-386023 blocked ET-1 and PE-induced ERK but not p38 and JNK activation in cardiomyocytes. Both compounds inhibited ET-1 and PEinduced protein synthesis and increased cell size, sarcomeric reorganization, and expression of ␤-myosin heavy chain in myocytes with IC 50 values of 1-2 M. Furthermore, both inhibitors significantly reduced ET-1-and PE-induced expression of atrial natriuretic factor. In cardiomyocytes transfected with a dominant-negative Raf, ET-1-and PE-induced increase in cell size, sarcomeric reorganization, and atrial natriuretic factor production were remarkably attenuated compared with the cells infected with an adenovirus-expressing green fluorescence protein. Taken together, our data strongly support the notion that the ERK signal pathway plays an essential role in ET-1-and PE-induced cardiomyocyte hypertrophy.

Background-Peroxisome proliferator-activated receptor-␣ (PPAR-␣) is expressed in the heart and regulates genes involved in myocardial fatty acid oxidation (FAO). The role of PPAR-␣ in acute ischemia/reperfusion myocardial injury remains unclear. Methods and Results-The coronary arteries of male mice were ligated for 30 minutes. After reperfusion for 24 hours, ischemic and infarct sizes were determined. A highly selective and potent PPAR-␣ agonist, GW7647, was administered by mouth for 2 days, and the third dose was given 1 hour before ischemia. GW7647 at 1 and 3 mg · kg Ϫ1 · d Ϫ1 reduced infarct size by 28% and 35%, respectively (PϽ0.01), and myocardial contractile dysfunction was also improved. Cardioprotection by GW7647 was completely abolished in PPAR-␣-null mice. Ischemia/reperfusion downregulated mRNA expression of cardiac PPAR-␣ and FAO enzyme genes, decreased myocardial FAO enzyme activity and in vivo cardiac fat oxidation, and increased serum levels of free fatty acids. All of these changes were reversed by GW7647. Moreover, GW7647 attenuated ischemia/reperfusion-induced release of multiple proinflammatory cytokines and inhibited neutrophil accumulation and myocardial expression of matrix metalloproteinases-9 and -2. Furthermore, GW7647 inhibited nuclear factor-B activation in the heart, accompanied by enhanced levels of inhibitor-B␣. Conclusions-Activation of PPAR-␣ protected the heart from reperfusion injury. This cardioprotection might be mediated through metabolic and antiinflammatory mechanisms. This novel effect of the PPAR-␣ agonist could provide an added benefit to patients treated with PPAR-␣ activators for dyslipidemia.

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