3-nitrotyrosine and Aortic-Aneurysm--Abdominal

In abdominal aortic aneurysm (AAA), pathophysiology deterioration of the medial aortic layer plays a critical role. Key players in vessel wall degeneration are reactive oxygen species (ROS), smooth muscle cell apoptosis, and extracellular matrix degeneration by matrix metalloproteinase-9 (MMP-9). Lipocalin-2, also neutrophil gelatinase-associated lipocalin (NGAL), is suggested to be involved in these degenerative processes in other cardiovascular diseases. We aimed to further investigate the role of NGAL in AAA development and rupture.. In this observational study, aneurysm tissue and blood of ruptured (n = 13) AAA patients were investigated versus nonruptured (n = 26) patients. Nondilated aortas (n = 5) from deceased patients and venous blood from healthy volunteers (n = 10) served as controls. NGAL concentrations in tissue and blood were measured by enzyme-linked immunosorbent assay and immunofluorescence microscopy. Nitrotyrosine (marker of ROS), MMP-9, and caspase-3 (marker of apoptosis) in aneurysm tissue were measured by immunofluorescence microscopy. AAA expansion rates were calculated retrospectively.. NGAL (in μg/mL) blood concentration in ruptured AAA was 46 (range 22-122) vs. 26 (range 6-55) in nonruptured AAA (P < 0.01) and 14 (range 12-22) in controls (P < 0.01). In the aneurysm wall of ruptured AAA, NGAL concentration was 4.7 (range 1.4-25) vs. 4.4 (range 0.2-14) in nonruptured AAA (not significant) and 1.8 (range 1.2-2.7) in nondilated aortas (P = 0.04). In the medial layer, NGAL correlated positively with nitrotyrosine (Rs = 0.80, P < 0.01), MMP-9 (Rs = 0.56, P = 0.02), and caspase-3 (Rs = 0.75, P = 0.01). NGAL did not correlate to AAA expansion rate in blood or tissue (P = 0.34 and P = 0.95, respectively).. This study demonstrates that NGAL blood concentration is higher in ruptured AAA patients than in nonruptured AAA. NGAL expression in the AAA wall is also higher than in nondilated aorta. Furthermore, its expression is associated with factors of vessel wall deterioration. Based on our study results, we could not determine NGAL as a biomarker for AAA growth or rupture. However, our findings do support a potential role of NGAL in the development of AAA.

Topics: Adult; Aged; Aged, 80 and over; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Apoptosis; Biomarkers; Caspase 3; Dilatation, Pathologic; Disease Progression; Female; Humans; Lipocalin-2; Male; Matrix Metalloproteinase 9; Middle Aged; Oxidative Stress; Retrospective Studies; Tyrosine; Up-Regulation; Vascular Remodeling

Extensive reactive oxygen and nitrogen species (also reactive species) production is a mechanism involved in abdominal aortic aneurysm (AAA) development. White blood cells (WBCs) are a known source of reactive species. Their production may be decreased by statins, thereby reducing the AAA growth rate. Reactive species production in circulating WBCs of AAA patients and the effect of statins on their production was investigated.. This observational study investigated reactive species production in vivo and ex vivo in circulating WBCs of AAA patients, using venous blood from patients prior to elective AAA repair (n = 34; 18 statin users) and from healthy volunteers (n = 10). Reactive species production was quantified in circulating WBCs using immunofluorescence microscopy: nitrotyrosine (footprint of peroxynitrite, a potent reactive nitrogen species) in snap frozen blood smears; mitochondrial superoxide and cytoplasmic hydrogen peroxide (both reactive oxygen species) by live cell imaging. Neutrophils, lymphocytes, and monocytes were examined individually.. In AAA patients using statins, the median nitrotyrosine level in neutrophils was 646 (range 422-2059), in lymphocytes 125 (range 74-343), and in monocytes 586 (range 291-663). Median levels in AAA patients not using statins were for neutrophils 928 (range 552-2095, p = .03), lymphocytes 156 (101-273, NS), and for monocytes 536 (range 535-1635, NS). The statin dose tended to correlate negatively with nitrotyrosine in neutrophils (R. It was found that the peroxynitrite footprint in circulating neutrophils and monocytes of AAA patients is higher than in controls. AAA patients treated with statins had a lower peroxynitrite footprint in neutrophils than non-statin users.

Topics: Adult; Aged; Aged, 80 and over; Aortic Aneurysm, Abdominal; Biomarkers; Case-Control Studies; Female; Humans; Hydrogen Peroxide; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Lymphocytes; Male; Middle Aged; Monocytes; Neutrophils; Peroxynitrous Acid; Tyrosine

Nitric Oxide (NO) is involved in the development and progression of abdominal aortic aneurysms (AAA). We found that inhibition of inducible NO synthase (iNOS) protects mice in an elastase-induced AAA model, significantly inhibiting the production of matrix metalloproteinase-13 (MMP-13). The extracellular MMP inducer (EMMPRIN; CD147) was increased in human AAA biopsies and in wild-type murine AAA but not in AAA from iNOS null mice. In cells overexpressing ectopic EMMPRIN, MMP-13 secretion was stimulated, whereas silencing of EMMPRIN by RNA interference led to significant inhibition of MMP-13 expression. In addition, elastase infusion of MMP-13 null mouse aortas induced a significant increase of EMMPRIN but reduced aortic dilatation when compared with wild-type mice, suggesting that NO-mediated AAA may be mediated through EMMPRIN induction of MMP-13. These findings were further verified in elastase-infused iNOS null mice, in which daily administration of NO caused a significant aortic dilatation and the expression of EMMPRIN and MMP-13. By contrast, in iNOS wild-type mice, pharmacological inhibition of iNOS by administration of 1400 W induced a reduction of aortic diameter and inhibition of MMP-13 and EMMPRIN expression when compared with control mice. Our results suggest that NO may regulate the development of AAA in part by inducing the expression of EMMPRIN and modulating the activity of MMP-13 in murine and human aneurysms.

Topics: Animals; Aortic Aneurysm, Abdominal; Basigin; Disease Progression; Down-Regulation; Endothelium, Vascular; Enzyme Induction; Extracellular Space; Humans; Matrix Metalloproteinase 13; Mice; Mice, Inbred C57BL; Nitric Oxide; Nitric Oxide Synthase Type II; Tyrosine

Vascular inflammation is implicated in the pathogenesis of atherosclerosis and abdominal aortic aneurysm (AAA), and is thought to involve reactive species such as the nitric oxide-derived oxidant peroxynitrite. In the present study nitrotyrosine was measured as a stable marker of peroxynitrite production in vivo.. Perioperative blood samples were obtained from patients undergoing elective open or endovascular repair of an AAA and from patients with intermittent claudication, smoking aged-matched controls, non-smoking aged-matched controls and non-smoking young healthy controls. Plasma nitrotyrosine was measured by an enzyme-linked immunosorbent assay.. The median plasma nitrotyrosine concentration in patients with an AAA (0.46 nmol nitrated bovine serum albumin equivalents per mg protein) was significantly higher than that in patients with intermittent claudication (0.35 nmol; P = 0.002), smoking controls (0.36 nmol; P = 0.001), non-smoking controls (0.35 nmol; P = 0.002) and young healthy controls (0.27 nmol; P < 0.001). Nitrotyrosine concentrations increased during early reperfusion in open AAA repair, but not during endovascular repair. AAA exclusion from the circulation reduced levels to control values (P = 0.001).. Patients with an AAA had raised levels of circulating nitrated proteins compared with patients with claudication and controls, suggesting a greater degree of ongoing inflammation that was not related to smoking.

Topics: Adult; Aged; Aortic Aneurysm, Abdominal; Biomarkers; Cohort Studies; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Middle Aged; Tyrosine

Abdominal aortic aneurysm (AAA) is an inflammatory disorder characterized by localized connective tissue degradation and smooth muscle cell (SMC) apoptosis, leading to aortic dilatation and rupture. Reactive oxygen species are abundantly produced during inflammatory processes and can stimulate connective tissue-degrading proteases and apoptosis of SMCs. We hypothesized that reactive oxygen species are locally increased in AAA and lead to enhanced oxidative stress. In aortas from patients undergoing surgical repair, superoxide levels (measured by lucigenin-enhanced chemiluminescence) were 2.5-fold higher in the AAA segments compared with the adjacent nonaneurysmal aortic (NA) segments (6638+/-2164 versus 2675+/-1027 relative light units for 5 minutes per millimeter squared, respectively; n=7). Formation of thiobarbituric acid-reactive substances and conjugated dienes, 2 indices of lipid peroxidation, were increased 3-fold in AAA compared with NA segments. Immunostaining for nitrotyrosine was significantly greater in AAA tissue. Dihydroethidium staining indicated that increased superoxide in AAA segments was localized to infiltrating inflammatory cells and to SMCs. Expression of the NADPH oxidase subunits p47(phox) and p22(phox) and NAD(P)H oxidase activity were increased in AAA segments compared with NA segments. Thus, oxidative stress is markedly increased in AAA, in part through the activation of NAD(P)H oxidase, and may contribute to the disease pathogenesis.

Topics: Aged; Aged, 80 and over; Aortic Aneurysm, Abdominal; Enzyme Activation; Female; Humans; Lipid Peroxidation; Male; Middle Aged; NADH, NADPH Oxidoreductases; NADP; NADPH Oxidases; Oxidative Stress; Reactive Oxygen Species; Superoxides; Thiobarbituric Acid Reactive Substances; Tyrosine

To determine if nitric oxide synthase (NOS) contributes to the pathophysiology of abdominal aortic aneurysms (AAAs), C57BL/6J mice underwent transient aortic injury to induce a chronic inflammatory response. Wild-type mice developed a significant increase in aortic diameter within 14 days of elastase perfusion (115+/-16%, 40% incidence of AAAs), along with intense and widespread staining for nitrotyrosine, mononuclear inflammation, and delayed destruction of the elastic lamellae. Expression of both endothelial and neuronal forms of NOS was substantially decreased within AAAs, whereas inducible NOS (iNOS) mRNA was increased 360%, and the enzyme was localized to infiltrating inflammatory cells. By using mice with targeted deletion of iNOS to evaluate the functional importance of this enzyme, male iNOS(-/-) mice developed the same extent of aneurysmal dilatation as congenic controls (121+/-22%, 40% incidence of AAAs) and exhibited similar structural features except for diminished nitrotyrosine staining. Aneurysmal dilatation was actually enhanced in female iNOS(-/-) mice (141+/-16%, 80% incidence of AAAs; P<0.05), but this effect was reversed by previous oophorectomy. Although extensive protein nitration and increased expression of iNOS accompany the development of elastase-induced experimental AAAs, iNOS is not required in this process and its absence may be deleterious.

Topics: Animals; Aortic Aneurysm, Abdominal; Dilatation, Pathologic; Female; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Ovariectomy; Pancreatic Elastase; RNA, Messenger; Tyrosine