Objective-Neutrophil gelatinase-associated lipocalin (NGAL) modulates the activity of matrix metalloproteinase (MMP) 9, an important mediator of vascular remodeling and plaque instability in atherosclerosis. This study aimed to analyze the expression of NGAL in atherosclerotic plaques and myocardial infarction (MI). Methods and Results-Atherosclerotic apolipoprotein E (apoE)Ϫ/Ϫ ϫ low-density lipoprotein receptor (LDLR) Ϫ/Ϫ and C57BL/6J control mice were exposed to brief hypoxic stress (10 minutes of 10% oxygen). Expression of the mouse NGAL homolog (24p3) and MMP-9 was analyzed 48 hours later by quantitative RT-PCR, immunohistochemistry, and zymography. Hypoxic stress increased NGAL/24p3 mRNA in the cardiac vasculature. NGAL/24p3 was also increased in atherosclerotic plaques of apolipoprotein E Ϫ/Ϫ ϫ LDLR Ϫ/Ϫ mice compared with C57BL/6J mice. Mice developing MI exhibited the highest plaque mRNA expression of NGAL/24p3 and MMP-9. Zymography revealed strong proteolytic activity in areas rich in 24p3 and MMP-9 protein. Immunohistochemistry performed on human carotid endarterectomy specimens and control tissue from the internal mammary artery showed colocalization of MMP-9 and NGAL with macrophages in the atherosclerotic plaques. Conclusions-NGAL/24p3 is increased in atherosclerotic plaques and MI. Colocalization with MMP-9 in areas with high-proteolytic activity suggests a role for NGAL/24p3 in modulating the MMP-9-mediated remodeling of plaques and infarcted hearts. Key Words: atherosclerosis Ⅲ myocardial infarction Ⅲ hypoxia Ⅲ matrix metalloproteinase Ⅲ remodeling C omplications to coronary atherosclerosis leading to myocardial infarction were previously believed to be because of the physical obstruction of the vessel lumen; however, 60% to 70% of myocardial infarctions (MIs) result from nonocclusive plaques. 1-4 Current evidence instead suggest that physical disruption of atherosclerotic plaques triggers thrombus formation, which may lead to MI. 5-7 The 2 major precipitating factors of thrombus formation are disruption of the plaque cap and erosion of its endothelial lining. Inflammation within the atherosclerotic plaque has been suggested to promote the progression toward plaque disruption by causing plaque instability. 8 Inflammatory mediators found in the atheroma have been shown to inhibit smooth muscle growth and collagen production and to augment matrix metalloproteinase (MMP) activity. 9 -12 This can result in decreased collagen content and weakening of plaque structure, leaving the fibrous cap prone to rupture.MMPs are a family of endopeptidases capable of degrading the molecular components of the extracellular matrix. They play important roles in a variety of pathological processes, such as atherosclerosis and tumor cell invasion. In particular, gelatinase B (MMP-9) is thought to be associated with diseases such as abdominal aortic aneurysm, atherosclerosis, and plaque rupture. 13 In cancer patients, urinary highmolecular weight MMPs have been shown to be independent predictors of metastatic cancers,...

Atherosclerosis is an inflammatory disorder involving complex interactions between vascular wall cells and invading inflammatory cells (14). Genetically modified mouse models of atherosclerosis, based on two pivotal genes of lipid metabolism, i.e., apolipoprotein E (ApoE) and the low-density lipoprotein receptor (LDLR), have been crossed with mice deficient in a specific gene of the LT cascade, e.g., 5-LO and BLT 1 , to investigate the impact of the gene product on the atherosclerotic process (9,(15)(16)(17).In the present study we examined the expression of 5-LO, FLAP, LTA4H, LTC4S, and the receptors BLT 1 , BLT 2 , CysLT 1 , and CysLT 2 in human carotid plaques and aortic lesions from both ApoE (Ϫ͞Ϫ) and compound ApoE (Ϫ͞Ϫ) ϫ LDLR (Ϫ͞Ϫ) mice. In contrast to the mouse models, we find that both 5-LO and LTA4H are expressed at increased levels and colocalize within human atherosclerotic lesions, with expression levels correlating with recent or ongoing symptoms of plaque instability. We also report that a selective inhibitor of LTA4H can block LTB 4 biosynthesis in plaque tissue, thus identifying LTA4H as a potential target for development of drugs for prevention and treatment of atherosclerosis and acute atherothrombotic events. Results Expression of 5LO, FLAP, LTA4H, and LTC4S mRNA in Human CarotidPlaque and Mouse Atherosclerotic Aorta. In the human carotid atherosclerotic lesions, the transcript levels of 5-LO, FLAP, and LTA4H were high, corresponding to a 7.5-fold (7.5 Ϯ 4.1, P Ͻ 0.001), 2.7-fold (2.7 Ϯ 1.3, P ϭ 0.003), and nearly 2-fold (1.9 Ϯ 1.0, P ϭ 0.03) increase relative to normal iliac arteries, respectively (Fig. 1A). In contrast, the levels of LTC4S mRNA were not significantly different from controls.In the ApoE (Ϫ͞Ϫ) mouse aorta, 5-LO and LTA4H mRNA levels were essentially unaltered, whereas FLAP and LTC4S mRNA showed a tendency to increase relative tissue from wild-type C57BL͞6J mice (Fig. 1B). In ApoE (Ϫ͞Ϫ) ϫ LDLR (Ϫ͞Ϫ) mice, the expression pattern of the enzymes was essentially the same as in ApoE (Ϫ͞Ϫ) mice, except that LTA4H mRNA levels were significantly increased (1.7 Ϯ 0.3, P ϭ 0.01) (Fig. 1C). Expression of 5-LO, FLAP, and LTA4H Protein in Human and MouseAtherosclerotic Lesions. Staining of human carotid plaque demonstrated prominent expression of 5-LO, FLAP, and LTA4H in intimal lesion areas that also stained positively for human macrophage marker CD163 (Fig. 2). The distribution of 5-LO,

Objective-Based on the emerging importance of the wingless (Wnt) pathways in inflammation and vascular biology, we hypothesized a role for Dickkopf-1 (DKK-1), a major modulator of Wnt signaling, in atherogenesis and plaque destabilization. Methods and Results-We report increased levels of DKK-1 in experimental (ApoE Ϫ/Ϫ mice) and clinical (patients with coronary artery disease ͓nϭ80͔ and patients with carotid plaque ͓nϭ47͔) atherosclerosis, both systemically (serum) and within the lesion, with particularly high levels in advanced and unstable disease. We identified platelets as an important cellular source of DKK-1 as shown by in vitro experiments and by immunostaining of thrombus material obtained at the site of plaque rupture in patients with acute ST-elevation myocardial infarction, with strong immunoreactivity in platelet aggregates. Our in vitro experiments identified a role for platelet-and endothelialderived DKK-1 in platelet-dependent endothelial activation, promoting enhanced release of inflammatory cytokines. These inflammatory effects of DKK-1 involved inhibition of the Wnt/␤-catenin pathway and activation of nuclear factor B. Key Words: atherosclerosis Ⅲ endothelium Ⅲ inflammation Ⅲ platelets P roteins from the wingless (Wnt) signaling pathways are involved in diverse developmental and physiological processes, including cardiac and vascular development. Wnt signals are transduced to the canonical and the noncanonical pathways for control of cell fate, cell movement, and tissue polarity. 1 The Wnt pathways are regulated by multiple families of secreted antagonists including soluble frizzled related receptors and dickkopfs (DKK). The best studied of these is DKK-1, which dampens Wnt signaling by binding to the low-density lipoprotein receptor-related protein (LRP)5/6 and a cell surface coreceptor, Kremen-1, promoting internalization of the receptor complex. 2 In adults, DKK-1 has been implicated in bone disease, cancer, and brain ischemia, and most recently, the destructive effect of tumor necrosis factor ␣ (TNF␣) on joints in rheumatoid arthritis was found to involve DKK-1. 2,3 Also, serum levels of DKK-1 give prognostic information in patients with multiple myeloma and other malignancies as well as in patients with osteoarthritis. 4,5 Recent evidence points to an important role of the Wnt signaling pathways in the regulation of inflammation. Thus, activation of the canonical Wnt/␤-catenin pathway induces proliferation and survival of endothelial cells, enhances monocyte adhesion, and regulates transendothelial migration of monocytes. 6 -9 Moreover, activation of the noncanonical pathway has been shown to regulate inflammatory responses of human monocytes and macrophages in vitro. 10,11 However, the interaction between the different proteins in the Wnt family is rather complex, and the role Conclusion-Our

BackgroundSeveral genome-wide association studies have recently linked a group of single nucleotide polymorphisms in the 9p21 region with cardiovascular disease. The molecular mechanisms of this link are not fully understood. We investigated five different expression microarray datasets in order to determine if the genotype had effect on expression of any gene transcript in aorta, mammary artery, carotid plaque and lymphoblastoid cells.Methodology/Principal FindingsAfter multiple testing correction, no genes were found to have relation to the rs2891168 risk genotype, either on a genome-wide scale or on a regional (8 MB) scale. The neighbouring ANRIL gene was found to have eight novel transcript variants not previously known from literature and these varied by tissue type. We therefore performed a detailed probe-level analysis and found small stretches of significant relation to genotype but no consistent associations. In all investigated tissues we found an inverse correlation between ANRIL and the MTAP gene and a positive correlation between ANRIL and CDKN2A and CDKN2B.Conclusions/SignificanceInvestigation of relation of the risk genotype to gene expression is complicated by the transcript complexity of the locus. With our investigation of a range of relevant tissue we wish to underscore the need for careful attention to the complexity of the alternative splicing issues in the region and its implications to the design of future gene expression studies.

In the present study, we found sustained inflammation due to NF-kappaB activation in human radiated arteries. The results are supported by previous in vitro findings suggesting that deoxyribonucleic acid injury, after radiation, activates NF-kappaB. We also suggest that HOXA9 might be involved in the regulation of NF-kappaB activation. The observed sustained inflammatory response can explain cardiovascular disease years after radiation.

Our findings confirmed a central role for inflammation and proteases in plaque instability, and highlighted haemoglobin metabolism and bone resorption as important pathways. Subgroup analysis suggested prolonged inflammation following the symptoms of plaque instability and calcification as a possible stabilizing mechanism by statins. In addition, transcriptional regulation may play an important role in the determination of plaque phenotype. The results from this study will serve as a basis for further exploration of molecular signatures in carotid atherosclerosis.

Neutrophil gelatinase-associated lipocalin (NGAL) has recently emerged as an important modulator of cell homeostasis. Elevated plasma NGAL levels, possibly because of activation of blood leukocytes, are associated with atherosclerosis. However, little is known about induction of NGAL expression in blood vessels. Using a rat carotid artery injury model, we found that NGAL was highly induced in the intima after angioplasty but was attenuated by adenovirus-mediated expression of a dominant-negative mutant of inhibitor of nuclear factor (NF)-B kinase ␤ (dnIKK␤). Expression of NGAL mRNA and protein was also up-regulated in an NF-B-dependent manner in rat and human vascular smooth muscle cells (SMCs) in response to interleukin-1␤ stimulation. Rat SMC-produced NGAL was present as mono-and homomeric forms in the cytosol and in a complex containing matrix metalloproteinase-9 (MMP-9) after secretion. In agreement with levels of NGAL, proteolytic activity of MMP-9 was markedly high in the intima of injured vessels and in the culture supernatant of activated intimal SMCs but was reduced in the vessels transduced with dnIKK␤. The present study reveals a previously unrecognized vascular response to angioplastic injury, characterized by NF-B-dependent expression of NGAL in vascular SMCs. Furthermore, SMC-produced NGAL interacts with MMP-9, a mechanism by which NGAL may modulate MMP-9 proteolytic activity in the vascular repair process.

Abstract-During everyday life, gravity constantly stresses the cardiovascular system in upright humans by diminishing venous return. This decreases cardiac output and induces systemic vasoconstriction to prevent blood pressure from falling. We therefore tested the hypothesis that entering weightlessness leads to a prompt increase in cardiac output and to systemic vasodilatation and that these effects persist for at least a week of weightlessness in space. Cardiac output and mean arterial pressure were measured in 8 healthy humans during acute 20-s periods of weightlessness in parabolic airplane flights and on the seventh and eighth day of weightlessness in 4 astronauts in space. The seated 1-G position acted as reference. Entering weightlessness promptly increased cardiac output by 29Ϯ7%, from 6.6Ϯ0.7 to 8.4Ϯ0.9 L min Ϫ1 (meanϮSEM; Pϭ0.003), whereas mean arterial pressure and heart rate were unaffected. Thus, systemic vascular resistance decreased by 24Ϯ4% (Pϭ0.017). After a week of weightlessness in space, cardiac output was increased by 22Ϯ8% from 5.1Ϯ0.3 to 6.1Ϯ0.1 L min Ϫ1 (Pϭ0.021), with mean arterial pressure and heart rate being unchanged so that systemic vascular resistance was decreased by 14Ϯ9% (Pϭ0.047). In conclusion, entering weightlessness promptly increases cardiac output and dilates the systemic circulation. This vasorelaxation persists for at least a week into spaceflight. Thus, it is probably healthy for the human cardiovascular system to fly in space. Key Words: blood pressure Ⅲ cardiac output Ⅲ cardiovascular diseases Ⅲ heart rate Ⅲ vascular resistance T hroughout evolution of mankind, gravity has constantly stressed the cardiovascular system by diminishing venous return of blood to the heart. 1 This gravity-induced decrease in venous return, and, thus in cardiac output, is detected by cardiopulmonary and arterial baroreflexes, which initiate constriction of the vasculature to prevent blood pressure from falling. Therefore, gravity is a chronic systemic vasoconstrictor in upright humans during normal everyday life.Previous cardiovascular measurements in astronauts in space indicate that cardiac output is increased by some 18% by weightlessness compared with upright standing or sitting on the ground and more so during the initial days of flight than at the end. 2,3 In these studies, blood pressure was not measured. In another study, Fritsch-Yelle et al 4 observed in 12 astronauts over several flights that the mean 24-hour diastolic arterial pressure, but not systolic pressure, was significantly decreased in space by some 5 mm Hg. This decrease was evident at the beginning and at the end of flight. However, cardiac output was not measured. Therefore, it is not known whether the unchanged systolic and decreased diastolic pressure in space is accounted for by systemic vasodilatation and whether systemic vasodilatation is evident from the very beginning and to the end of flight.We therefore tested the hypothesis that the weightlessnessinduced increase in cardiac output leads to systemic vasodilata...