Biomedical subjects

Marie-Luise Brennan

Publications and source records attributed to Marie-Luise Brennan.

At least 19 recordsLinked to original sources

PubMed2007

Effects of the antioxidant succinobucol (AGI-1067) on human atherosclerosis in a randomized clinical trial.

BACKGROUND: The antioxidant AGI-1067 was shown to reduce experimental atherosclerosis. The present study originally intended to study restenosis as a primary endpoint but was subsequently modified to primarily investigate the effects of AGI-1067 on coronary atherosclerosis. METHODS AND RESULTS: This placebo-controlled randomized trial assessed the effects of AGI-1067 280 mg qd started before percutaneous coronary intervention (PCI) and administered for 12 months after PCI on atherosclerosis progression as assessed by coronary intravascular ultrasound (IVUS). Among patients with IVUS examinations considered technically adequate both at baseline and follow-up upon central laboratory assessments (n=232), plaque volume was not significantly modified with placebo (least squares mean change: -0.4mm(3), P=0.85 versus baseline), but was significantly reduced by -4.0mm(3) at end of treatment in the AGI-1067 group (P=0.001 versus baseline, P=0.12 versus placebo). LDL-cholesterol varied by -9% and +4% in the placebo and AGI-1067 groups, respectively (P<0.05 between groups), and HDL-cholesterol was reduced by 1% with placebo and 14% with AGI-1067 (P<0.05 between groups). Plasma myeloperoxidase was reduced by 6% with AGI-1067 (P<0.05) but hs-CRP was not significantly different between groups. CONCLUSIONS: Atherosclerosis regression (-4.0mm(3)) was observed in patients treated with AGI-1067, although this was not significantly different from placebo. The anti-inflammatory effect of AGI-1067 is supported by reduced levels of myeloperoxidase.

Aged↗

PubMed2006

Systemic elevations of free radical oxidation products of arachidonic acid are associated with angiographic evidence of coronary artery disease.

Oxidant stress is widely believed to participate in cardiovascular disease pathogenesis. However, progress in defining appropriate systemic antioxidant targeted therapies has been hindered by uncertainty in defining clinically relevant systemic oxidant stress measures. In a case control study, 50 subjects with CAD (>50% stenosis in one or more major coronary vessels) and 54 without CAD (<30% stenosis in all major coronary vessels) were tested. Plasma was isolated and stored under conditions designed to prevent artificial lipid peroxidation. Systemic levels of multiple (n=9) specific fatty acid oxidation products including individual hydroxyoctadecadienoic acids (HODEs), hydroxyeicosatetraenoic acids (HETEs), and F(2)-isoprostanes were simultaneously measured by high-performance liquid chromatography (HPLC) with on-line tandem mass spectrometry, along with traditional risk factors and C-reactive protein (CRP) levels. Of the markers monitored, only 9-HETE and F(2)-isoprostanes, both products of free radical-mediated arachidonic acid oxidation, were significantly elevated in patients with angiographically defined CAD (9-HETE, 8.7 +/- 4 vs 6.8 +/- 4 micromol/mol arachidonate, P = 0.011; and F(2)-isoprostanes, 9.4 +/- 5 vs 6.2 +/- 3 micromol/mol arachidonate, P < 0.001). In multivariable analyses with simultaneous adjustment for Framingham risk score and C-reactive protein, 9-HETE (4th quartile OR = 4.8, 95% CI=1.3 to 17.1; P = 0.016) and F(2)-isoprostanes (4th quartile OR=9.7, 95% CI=2.56 to 36.9; P < 0.001) remained strong and independent predictors of CAD risk. Systemic levels of 9-HETE and F(2)-isoprostanes are independently associated with angiographic evidence of CAD and appear superior to other specific oxidation products of arachidonic and linoleic acids as predictors of the presence of angiographically evident coronary artery disease.

Arachidonic Acid↗

PubMed2006

Plasma myeloperoxidase levels in patients with chronic heart failure.

Increased oxidative stress and endothelial dysfunction are commonly observed in patients with chronic heart failure (HF). The relation between myeloperoxidase (MPO), an inflammatory marker with mechanistic links to plaque vulnerability and abnormal ventricular remodeling, and degrees of severity in chronic HF has not been reported. Plasma MPO levels were measured in 105 normal controls (no history of HF or left ventricular dysfunction) and 102 patients with chronic systolic HF (left ventricular ejection fraction <50%), and the relations among plasma MPO levels, plasma B-type natriuretic peptide levels, and the left ventricular ejection fraction were examined. Plasma MPO levels in patients with chronic systolic HF were significantly elevated compared with those of healthy controls (1,158 +/- 2,965 vs 204 +/- 139 pM, p <0.0001). Plasma MPO levels increased in parallel with increasing New York Heart Association class (p <0.0001) and were correlated with plasma B-type natriuretic peptide levels (Spearman's r = 0.39, p <0.0001). Levels of MPO were strongly associated with the prevalence of HF (unadjusted odds ratio 30.3, 95% confidence interval 11.1 to 94.5) and remained significant when adjusted for age and B-type natriuretic peptide (odds ratio 27.7, 95% confidence interval 3.6 to 371.1). In conclusion, in a cohort of patients with chronic HF, plasma MPO levels were elevated compared with those of normal controls and were associated with worsening functional class.

Adult↗

PubMed2006

Serum myeloperoxidase and mortality in maintenance hemodialysis patients.

BACKGROUND: During inflammation, myeloperoxidase (MPO) is released, for which its measurement in systemic circulation may be used as an index of leukocyte activation and oxidant stress. MPO levels correlate with angiographic evidence of coronary atherosclerosis and cardiovascular events in subjects with chest pain within the general population. We hypothesized that serum MPO levels are associated with adverse clinical outcomes in maintenance hemodialysis (MHD) patients. METHODS: MPO levels were determined in serum samples from 356 MHD patients at the start of a 3-year cohort. RESULTS: Patients (46% women, 28% blacks, 54% with diabetes) were 54.6 +/- 14.6 (SD) years old and had undergone MHD for a median period of 26 months. Measured serum MPO level was 2,005 +/- 1,877 pmol/L (median, 1,444 pmol/L; interquartile range, 861 to 2,490 pmol/L). MHD patients with greater total body fat had greater MPO levels. MPO level had statistically significant (P < 0.01) and positive correlations with values for serum C-reactive protein (CRP; r = +0.15), interleukin 6 (IL-6; r = +0.23), tumor necrosis factor alpha (TNF-alpha; r = +0.21), and white blood cell count (r = +0.21). A death hazard ratio for each 1,000-pmol/L increase in serum MPO level was 1.14 (95% confidence interval [CI], 1.03 to 1.26; P = 0.01) after controlling for age, race (black), diabetes mellitus, dialysis vintage, Charlson comorbidity score, history of previous cardiovascular disease, blood hemoglobin level, and serum concentrations of albumin, CRP, IL-6, and TNF-alpha. After dividing MPO values into 3 equal groups (tertiles), the death hazard ratio of the highest tertile (versus the middle tertile) was 1.82 (95% CI, 1.07 to 3.10; P = 0.03). CONCLUSION: Serum MPO levels correlate with levels of markers of inflammation and prospective mortality risk in MHD patients.

Adult↗

PubMed2005

Myeloperoxidase-generated oxidants modulate left ventricular remodeling but not infarct size after myocardial infarction.

BACKGROUND: Inflammation after myocardial infarction (MI) heralds worse left ventricular (LV) function and clinical outcomes. However, whether inflammation affects LV function by extending myonecrosis and/or altering LV remodeling remains unknown. We hypothesized that cytotoxic aldehydes generated during oxidative stress may adversely affect remodeling and infarct size. One theoretical source of reactive aldehydes is oxidation of common alpha-amino acids by myeloperoxidase (MPO) released by leukocytes. However, a role for MPO in formation of aldehydes in vivo and the functional consequences of MPO-generated oxidants in ischemia/reperfusion models of MI have not been established. METHODS AND RESULTS: In studies with cell types found in vascular tissue, MPO-oxidation products of glycine (formaldehyde) and threonine (acrolein) were the most cytotoxic. Mass spectrometry studies of myocardial tissue from murine models of acute MI (both chronic left anterior descending coronary artery ligation and ischemia/reperfusion injury) confirmed that MPO serves as a major enzymatic source in the generation of these cytotoxic aldehydes. Interestingly, although MPO-null mice experienced 35.1% (P<0.001) less LV dilation and a 52.2% (P<0.0001) improvement in LV function compared with wild-type mice 24 days after ischemia/reperfusion injury, no difference in infarct size between wild-type and MPO-null mice was noted. CONCLUSIONS: The present data separate inflammatory effects on infarct size and LV remodeling and demonstrate that MPO-generated oxidants do not significantly affect tissue necrosis after MI but rather have a profound adverse effect on LV remodeling and function.

Acrolein↗

PubMed2005

p53 is a suppressor of inflammatory response in mice.

Chronic inflammation is known to promote cancer, suggesting that negative regulation of inflammation is likely to be tumor suppressive. We found that p53 is a general inhibitor of inflammation that acts as an antagonist of nuclear factor kappaB (NFkappaB). We first observed striking similarities in global gene expression profiles in human prostate cancer cells LNCaP transduced with p53 inhibitory genetic element or treated with TNF, suggesting that p53 inhibits transcription of TNF-inducible genes that are largely regulated by NFkappaB. Consistently, ectopically expressed p53 acts as an inhibitor of transcription of NFkappaB-dependent promoters. Furthermore, suppression of inflammatory response by p53 was observed in vivo in mice by comparing wild-type and p53 null animals at molecular (inhibition of transcription of genes encoding cytokines and chemokines, reducing accumulation of reactive oxygen species and protein oxidation products), cellular (activation of macrophages and neutrophil clearance) and organismal (high levels of metabolic markers of inflammation in tissues of p53-deficient mice and their hypersensitivity to LPS) levels. These observations indicate that p53, acting through suppression of NFkappaB, plays the role of a general "buffer" of innate immune response in vivo that is well consistent with its tumor suppressor function and frequent constitutive activation of NFkappaB in tumors.

Animals↗

PubMed2005

Levels of soluble endothelium-derived adhesion molecules in patients with sickle cell disease are associated with pulmonary hypertension, organ dysfunction, and mortality.

Endothelial cell adhesion molecules orchestrate the recruitment and binding of inflammatory cells to vascular endothelium. With endothelial dysfunction and vascular injury, the levels of endothelial bound and soluble adhesion molecules increase. Such expression is modulated by nitric oxide (NO), and in patients with sickle cell disease (SCD), these levels are inversely associated with measures of NO bioavailability. To further evaluate the role of endothelial dysfunction in a population study of SCD, we have measured the levels of soluble endothelium-derived adhesion molecules in the plasma specimens of 160 adult patients with SCD during steady state. Consistent with a link between endothelial dysfunction and end-organ disease, we found that higher levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) were associated with markers indicating renal dysfunction and hepatic impairment. Analysis of soluble intercellular cell adhesion molecule-1 (sICAM-1), sE-selectin and sP-selectin levels indicated partially overlapping associations with sVCAM-1, with an additional association with inflammatory stress and triglyceride levels. Importantly, increased soluble adhesion molecule expression correlated with severity of pulmonary hypertension, a clinical manifestation of endothelial dysfunction. Soluble VCAM-1, ICAM-1, and E-selectin were independently associated with the risk of mortality in this cohort. Our data are consistent with steady state levels of soluble adhesion molecules as markers of pulmonary hypertension and risk of death.

Adolescent↗

PubMed2004

Serum myeloperoxidase levels independently predict endothelial dysfunction in humans.

BACKGROUND: In vitro and animal studies demonstrate that myeloperoxidase catalytically consumes nitric oxide as a substrate, limiting its bioavailability and function. We therefore hypothesized that circulating levels of myeloperoxidase would predict risk of endothelial dysfunction in human subjects. METHODS AND RESULTS: Serum myeloperoxidase was measured by enzyme-linked immunoassay, and brachial artery flow-mediated dilation and nitroglycerin-mediated dilation were determined by ultrasound in a hospital-based population of 298 subjects participating in an ongoing study of the clinical correlates of endothelial dysfunction (age, 51+/-16; 61% men, 51% with cardiovascular disease). A strong inverse relation between brachial artery flow-mediated dilation and increasing quartile of serum myeloperoxidase level was observed (11.0+/-6.0%, 9.4+/-5.3%, 8.6+/-5.8%, and 6.4+/-4.5% for quartiles 1 through 4, respectively; P<0.001 for trend). Using the median as a cut point to define endothelial dysfunction, increasing quartile of myeloperoxidase predicted endothelial dysfunction after adjustment for classic cardiovascular disease risk factors, C-reactive protein levels, prevalence of cardiovascular disease, and ongoing treatment with cardiovascular medications (OR, 6.4; 95% CI, 2.6 to 16; P=0.001 for highest versus lowest quartile). CONCLUSIONS: Serum myeloperoxidase levels serve as a strong and independent predictor of endothelial dysfunction in human subjects. Myeloperoxidase-mediated endothelial dysfunction may be an important mechanistic link between oxidation, inflammation, and cardiovascular disease.

Adult↗

PubMed2004

Myeloperoxidase deficiency enhances inflammation after allogeneic marrow transplantation.

Myeloperoxidase (MPO)-derived oxidants participate in the respiratory antimicrobial defense system but are also implicated in oxidant-mediated acute lung injury. We hypothesized that MPO contributes to lung injury commonly observed after bone marrow transplantation (BMT). MPO-sufficient (MPO+/+) and -deficient (MPO-/-) mice were given cyclophosphamide and lethally irradiated followed by infusion of inflammation-inducing donor spleen T cells at time of BMT. Despite suppressed generation of nitrative stress, MPO-/- recipient mice unexpectedly exhibited accelerated weight loss and increased markers of lung dysfunction compared with MPO+/+ mice. The increased lung injury during MPO deficiency was a result of donor T cell-dependent inflammatory responses because bronchoalveolar lavage fluids (BALF) from MPO-/- mice contained increased numbers of inflammatory cells and higher levels of the proinflammatory cytokine TNF-alpha and the monocyte chemoattractant protein-1 compared with wild-type mice. Enhanced inflammation in MPO-/- mice was associated with suppressed apoptosis of BALF inflammatory cells. The inflammatory process in MPO-/- recipients was also associated with enhanced necrosis of freshly isolated alveolar type II cells, critical for preventing capillary leak. We conclude that suppressed MPO-derived oxidative/nitrative stress is associated with enhanced lung inflammation and persistent alveolar epithelial injury.

Animals↗

PubMed2004

Ascorbate decreases Fabry cerebral hyperperfusion suggesting a reactive oxygen species abnormality: an arterial spin tagging study.

PURPOSE: To test the hypothesis that reactive oxygen species contribute to the cerebral hyperperfusion in Fabry disease. MATERIAL AND METHODS: We examined the effect of intravenous injection of ascorbate on cerebral blood flow (CBF) using magnetic resonance arterial spin tagging. Nineteen patients with Fabry disease and 15 control subjects were studied as part of a randomized double-blind placebo-controlled trial of enzyme replacement therapy (ERT). RESULTS: Vertebro-basilar hyperperfusion was observed in patients with Fabry disease. A decrease in systemic ascorbate levels relative to healthy controls was found in the patients. CBF decreased after ascorbate infusion in both control subjects and patients treated with ERT. The placebo group had a significantly delayed decrease in the CBF response after ascorbate infusion. Myeloperoxidase levels were elevated in Fabry patients, consistent with ongoing inflammatory processes in these patients. CONCLUSION: Increased CBF in Fabry disease may be related to increased production of reactive oxygen species, while low plasma ascorbate levels suggests a global redox imbalance. These abnormalities were improved by ERT. These observations have implications regarding oxidative processes contributing to accelerated atherosclerosis in Fabry disease.

Adult↗

PubMed2004

Apolipoprotein A-I is a selective target for myeloperoxidase-catalyzed oxidation and functional impairment in subjects with cardiovascular disease.

In recent studies we demonstrated that systemic levels of protein-bound nitrotyrosine (NO(2)Tyr) and myeloperoxidase (MPO), a protein that catalyzes generation of nitrating oxidants, serve as independent predictors of atherosclerotic risk, burden, and incident cardiac events. We now show both that apolipoprotein A-I (apoA-I), the primary protein constituent of HDL, is a selective target for MPO-catalyzed nitration and chlorination in vivo and that MPO-catalyzed oxidation of HDL and apoA-I results in selective inhibition in ABCA1-dependent cholesterol efflux from macrophages. Dramatic selective enrichment in NO(2)Tyr and chlorotyrosine (ClTyr) content within apoA-I recovered from serum and human atherosclerotic lesions is noted, and analysis of serum from sequential subjects demonstrates that the NO(2)Tyr and ClTyr contents of apoA-I are markedly higher in individuals with cardiovascular disease (CVD). Analysis of circulating HDL further reveals that higher NO(2)Tyr and ClTyr contents of the lipoprotein are each significantly associated with diminished ABCA1-dependent cholesterol efflux capacity of the lipoprotein. MPO as a likely mechanism for oxidative modification of apoA-I in vivo is apparently facilitated by MPO binding to apoA-I, as revealed by cross-immunoprecipitation studies in plasma, recovery of MPO within HDL-like particles isolated from human atheroma, and identification of a probable contact site between the apoA-I moiety of HDL and MPO. To our knowledge, the present results provide the first direct evidence for apoA-I as a selective target for MPO-catalyzed oxidative modification in human atheroma. They also suggest a potential mechanism for MPO-dependent generation of a proatherogenic dysfunctional form of HDL in vivo.

ATP Binding Cassette Transporter 1↗

PubMed2003

Identification of alpha-chloro fatty aldehydes and unsaturated lysophosphatidylcholine molecular species in human atherosclerotic lesions.

BACKGROUND: A role for myeloperoxidase (MPO) as a mediator of coronary artery disease and acute coronary syndromes has recently received considerable attention. Although active MPO and hypochlorite-modified proteins and peptides have been detected in human atherosclerotic lesions, detection of novel chlorinated oxidized lipid species with proatherogenic properties in vivo has not yet been reported. In this study we show that MPO-generated reactive chlorinating species promote selective oxidative cleavage of plasmalogens, liberating alpha-chloro fatty aldehydes and unsaturated lysophosphatidylcholine in human atherosclerotic lesions. METHODS AND RESULTS: Stable isotope dilution gas chromatography-mass spectrometry methods were used to identify and quantitate the alpha-chloro fatty aldehyde, 2-chlorohexadecanal, in atherosclerotic versus normal human aorta. Compared with normal aorta, 2-chlorohexadecanal levels were elevated more than 1400-fold in atherosclerotic tissues. Parallel electrospray ionization mass spectrometry studies confirmed 34- and 20-fold increases in the plasmalogen cooxidation products, unsaturated lysophosphatidylcholine molecular species containing linoleic and arachidonic acid, respectively, within atherosclerotic compared with normal aorta. Unsaturated lysophosphatidylcholine containing docosahexaenoic acid was also detected in atherosclerotic but not in normal aorta. Exposure of primary human coronary artery endothelial cells to plasmalogen-derived lysophosphatidylcholine molecular species produced marked increases in P-selectin surface expression. CONCLUSIONS: The present studies demonstrate that plasmalogens are attacked by MPO-derived reactive chlorinating species within human atheroma. The resultant species formed, alpha-chloro fatty aldehydes and unsaturated lysophospholipids, possess proatherogenic properties, as shown by induction of P-selectin surface expression in primary human coronary artery endothelial cells.

Aldehydes↗

PubMed2003

Prognostic value of myeloperoxidase in patients with chest pain.

BACKGROUND: Inflammation is linked to adverse outcomes in acute coronary syndromes. Myeloperoxidase, an abundant leukocyte enzyme, is elevated in culprit lesions that have fissured or ruptured in patients with sudden death from cardiac causes. Numerous lines of evidence suggest mechanistic links between myeloperoxidase and both inflammation and cardiovascular disease. METHODS: We assessed the value of plasma levels of myeloperoxidase as a predictor of the risk of cardiovascular events in 604 sequential patients presenting to the emergency department with chest pain. RESULTS: Initial plasma myeloperoxidase levels predicted the risk of myocardial infarction, even in patients who are negative for troponin T (<0.1 ng per milliliter) at base line (P<0.001). Myeloperoxidase levels at presentation also predicted the risk of major adverse cardiac events (myocardial infarction, the need for revascularization, or death) within 30 days and 6 months after presentation (P<0.001). In patients without evidence of myocardial necrosis (defined as those who were negative for troponin T), the base-line myeloperoxidase levels independently predicted the risk of major adverse coronary events at 30 days (unadjusted 2nd, 3rd, and 4th quartile odds ratios, 2.2 [95 percent confidence interval, 1.1 to 4.6], 4.2 [95 percent confidence interval, 2.1 to 8.4], and 4.1 [95 percent confidence interval, 2.0 to 8.4], respectively) and at 6 months. CONCLUSIONS: A single initial measurement of plasma myeloperoxidase independently predicts the early risk of myocardial infarction, as well as the risk of major adverse cardiac events in the ensuing 30-day and 6-month periods. Myeloperoxidase levels, in contrast to troponin T, creatine kinase MB isoform, and C-reactive protein levels, identified patients at risk for cardiac events in the absence of myocardial necrosis, highlighting its potential usefulness for risk stratification among patients who present with chest pain.

Aged↗

PubMed2003

Statins promote potent systemic antioxidant effects through specific inflammatory pathways.

BACKGROUND: The pleiotropic actions of hydroxymethylglutaryl CoA reductase inhibitors (statins) include antiinflammatory and antioxidant actions. We recently reported that statins induce reductions in plasma protein levels of nitrotyrosine (NO2Tyr), a modification generated by nitric oxide-derived oxidants. Whether alternative oxidative pathways are suppressed in vivo after statin administration has not yet been reported. METHODS AND RESULTS: As an extension of our prior study, hypercholesterolemic subjects with no known coronary artery disease were evaluated at baseline and after 12 weeks of atorvastatin therapy (10 mg/d). Plasma levels of protein-bound chlorotyrosine, NO2Tyr, dityrosine, and orthotyrosine, specific molecular fingerprints for distinct oxidative pathways upregulated in atheroma, were determined by mass spectrometry. In parallel, alterations in lipoproteins and C-reactive protein were determined. Statin therapy caused significant reductions in chlorotyrosine, NO2Tyr, and dityrosine (30%, 25%, and 32%, respectively; P<0.02 each) that were similar in magnitude to reductions in total cholesterol and apolipoprotein B-100 (25% and 29%, P<0.001 each). Nonsignificant decreases in orthotyrosine and C-reactive protein levels were observed (9% and 11%, respectively; P>0.10 each). Statin-induced reductions in oxidation markers were independent of decreases in lipids and lipoproteins. CONCLUSIONS: Statins promote potent systemic antioxidant effects through suppression of distinct oxidation pathways. The major pathways inhibited include formation of myeloperoxidase-derived and nitric oxide-derived oxidants, species implicated in atherogenesis. The present results suggest potential mechanisms that may contribute to the beneficial actions of statins. They also have important implications for monitoring the antiinflammatory and antioxidant actions of these agents.

Antioxidants↗

PubMed2003

Association of nitrotyrosine levels with cardiovascular disease and modulation by statin therapy.

CONTEXT: Formation of nitric oxide-derived oxidants may serve as a mechanism linking inflammation to development of atherosclerosis. Nitrotyrosine, a specific marker for protein modification by nitric oxide-derived oxidants, is enriched in human atherosclerotic lesions and low-density lipoprotein (LDL) recovered from human atheroma. OBJECTIVES: To determine whether systemic levels of nitrotyrosine are associated with the prevalence of coronary artery disease (CAD) and are modulated by hydroxymethylglutaryl coenzyme-A reductase inhibitor (statin) therapy. DESIGN, SETTING, AND PATIENTS: A case-control and interventional study at 2 urban tertiary-care referral centers; recruitment for each was from June 1, 2001, until January 1, 2002. For the case-control study, 100 case-patients with established CAD and 108 patients with no clinically evident CAD were recruited consecutively. In the interventional study, participants aged 21 years or older with hypercholesterolemia (LDL cholesterol > or =130 mg/dL [> or =3.5 mmol/L]) underwent nutrition and exercise counseling. Those whose levels did not decrease with 6 to 8 weeks were enrolled in the study (n = 35). For 12 weeks, they received 10 mg/d of oral atorvastatin therapy. MAIN OUTCOME MEASURES: In the case-control study, the association between systemic levels of protein-bound nitrotyrosine, CAD risk, and presence of CAD. In the interventional study, the change in nitrotyrosine, lipoprotein, and C-reactive protein (CRP) levels. RESULTS: Nitrotyrosine levels were significantly higher among patients with CAD (median 9.1 micromol/mol [interquartile range, 4.8-13.8 micromol/mol] tyrosine vs 5.2 micromol/mol [interquartile range, 2.2-8.4 micromol/mol]; P<.001). Patients in the upper quartile of nitrotyrosine (29%; P<.001) had a higher odds of CAD compared with those in the lowest quartile (unadjusted odds ratio, 6.1; 95% confidence interval, 2.6-14.0; P<.001). In multivariate models adjusting for Framingham Global Risk Score and CRP, upper quartiles of nitrotyrosine remained associated with CAD (odds ratio, 4.4; 95% confidence interval, 1.8-10.6; P<.001). Statin therapy reduced nitrotyrosine levels significantly (25%; P<.02) with a magnitude similar to reductions in total cholesterol levels (25%; P<.001) and LDL particle number (29%; P<.001) yet were independent of alterations in lipoproteins and inflammatory markers like CRP. CONCLUSIONS: The findings from this preliminary study indicate that nitrotyrosine levels are associated with the presence of CAD and appear to be modulated by statin therapy. These results suggest a potential role for nitric oxide-derived oxidants as inflammatory mediators in CAD and may have implications for atherosclerosis risk assessment and monitoring of anti-inflammatory actions of statins.

Adult↗

PubMed2003

Myeloperoxidase and plasminogen activator inhibitor 1 play a central role in ventricular remodeling after myocardial infarction.

Left ventricular (LV) remodeling after myocardial infarction (MI) results in LV dilation, a major cause of congestive heart failure and sudden cardiac death. Ischemic injury and the ensuing inflammatory response participate in LV remodeling, leading to myocardial rupture and LV dilation. Myeloperoxidase (MPO), which accumulates in the infarct zone, is released from neutrophils and monocytes leading to the formation of reactive chlorinating species capable of oxidizing proteins and altering biological function. We studied acute myocardial infarction (AMI) in a chronic coronary artery ligation model in MPO null mice (MPO(-/-)). MPO(-/-) demonstrated decreased leukocyte infiltration, significant reduction in LV dilation, and marked preservation of LV function. The mechanism appears to be due to decreased oxidative inactivation of plasminogen activator inhibitor 1 (PAI-1) in the MPO(-/-), leading to decreased tissue plasmin activity. MPO and PAI-1 are shown to have a critical role in the LV response immediately after MI, as demonstrated by markedly delayed myocardial rupture in the MPO(-/-) and accelerated rupture in the PAI-1(-/-). These data offer a mechanistic link between inflammation and LV remodeling by demonstrating a heretofore unrecognized role for MPO and PAI-1 in orchestrating the myocardial response to AMI.

Animals↗

PubMed2003

Isolevuglandins, a novel class of isoprostenoid derivatives, function as integrated sensors of oxidant stress and are generated by myeloperoxidase in vivo.

Isolevuglandins (isoLGs) are a family of reactive gamma-ketoaldehydes generated by free radical oxidation of arachidonate-containing lipids through the isoprostane pathway. Elevated plasma levels of isoLG protein adducts are observed in subjects with atherosclerosis compared with age/gender-matched controls. However, mechanisms for the generation of isoLGs in vivo are not established. Here we show that free radical-induced peroxidation promoted by the myeloperoxidase (MPO)/H2O2 system of leukocytes serves as one mechanism for the generation of isoLGs in vivo. Using a Candida sepsis model of inflammation, we demonstrate 3.5- and 2.7-fold increases in iso[4]LGE2 and isoLGE2 adducts of plasma proteins after pathogen exposure in wild-type mice. Plasma levels of F2 isoprostanes were not significantly increased after pathogen challenge in this model. MPO knockout mice demonstrated significant reductions (34%, P=0.003) in plasma levels of iso[4]LGE2 protein adducts after pathogen challenge compared with wild-type mice. Mass spectrometry and immunochemical methods demonstrate MPO-dependent formation of iso[4]LGE2 and isoLGE2 phospholipids and their corresponding isoLG protein adducts in model systems. The present studies thus identify MPO as one pathway for generation of isoLGs in vivo. They also suggest that long-lived protein isoLG adducts may serve as an alternative integrated sensor of oxidant stress in vivo.

Animals↗

PubMed2003

Emerging role of myeloperoxidase and oxidant stress markers in cardiovascular risk assessment.

PURPOSE OF REVIEW: Myeloperoxidase, an abundant leukocyte protein that generates reactive oxidant species, is present and catalytically active within atherosclerotic lesions. Numerous lines of evidence suggest mechanistic links between myeloperoxidase, inflammation and both acute and chronic manifestations of cardiovascular disease. RECENT FINDINGS: Myeloperoxidase generates reactive oxidant species as part of its function in innate host defense mechanisms. The reactive species formed, however, may also damage normal tissues, contributing to inflammatory injury. Recent studies suggest that MPO-generated oxidants participate in multiple processes relevant to cardiovascular disease development and outcomes, including induction of foam cell formation, endothelial dysfunction, development of vulnerable plaque, and ventricular remodeling following acute myocardial infarction. Of note, measurements of myeloperoxidase mass and activity may be useful in cardiac risk stratification, both for chronic disease assessment, as well as in identification of patients at risk in the acute setting. SUMMARY: The inflammatory protein myeloperoxidase is present, active and mechanistically poised to participate in the initiation and progression of cardiovascular disease. The many links between myeloperoxidase, oxidation and cardiovascular disease suggest this leukocyte protein may have clinical utility in risk stratification for cardiovascular disease status and outcomes.

Animals↗