The aim of this research is to identify the cellular antioxidant effects of chitin oligosaccharides (NA-COS; Mw 229.21–593.12 Da) produced by acidic hydrolysis of crab chitin. The inhibitory effect of NA-COS on myeloperoxidase (MPO) activity in human myeloid cells (HL-60) and oxidation of DNA and protein in mouse macrophages (Raw 264.7) were identified. Furthermore, their direct radical scavenging effect by 2′,7′-dichlorofluorescein (DCF) intensity and intracellular glutathione (GSH) level were significantly increased in a time dependent manner, respectively. These results suggest that NA-COS act as a potent antioxidant in live cells.
ARTICLE
Accumulation of Myeloperoxidase-Positive Neutrophils in Atherosclerotic Lesions in LDLR–/– Mice
Objective—
Atherosclerosis is a chronic inflammatory disease in which the immune system plays an important role. Neutrophils have not been thoroughly studied in the context of atherogenesis. Here, we investigated neutrophils in the development of murine atherosclerotic lesions.
Methods and Results—
LDLR–/– mice were given a high-fat diet for different time periods and subsequently atherosclerotic lesions were studied by immunohistochemistry. Staining with anti–Ly-6G monoclonal antibody, a specific marker for neutrophils, revealed a marked accumulation of neutrophils during atherosclerosis development. Neutrophils were observed in the lesion, attached to the cap, and in the arterial adventitia. In addition, at some sites, neutrophil accumulation colocalized with endothelial E-selectin expression. Immunofluorescence double staining with anti-myeloperoxidase and anti–Ly-6G antibodies demonstrated the presence of myeloperoxidase in atherosclerotic lesions and its colocalization with neutrophils. After introducing the high-fat diet, levels of circulating myeloperoxidase in plasma strongly increased, with a peak at 6 weeks and a subsequent decrease to almost normal levels after 16 weeks of diet.
Conclusions—
We here demonstrate for the first time the presence of neutrophils and myeloperoxidase in murine atherosclerotic lesions. As a major cell type in inflammatory responses the neutrophil may also be an important mediator in the development of atherosclerosis.
We identified myeloperoxidase-positive neutrophils in mouse atherosclerotic lesions. Although neutrophils were not detected in early lesions, they were abundantly present in more advanced stages. In addition, circulating myeloperoxidase levels were strongly increased by high-fat feeding of the mice. Therefore, neutrophils should be considered as a potential important cellular mediator in atherogenesis.
Atherosclerosis is a chronic inflammatory disease in which the immune system plays an important role. Neutrophils have not been thoroughly studied in the context of atherogenesis. Here, we investigated neutrophils in the development of murine atherosclerotic lesions.
Methods and Results—
LDLR–/– mice were given a high-fat diet for different time periods and subsequently atherosclerotic lesions were studied by immunohistochemistry. Staining with anti–Ly-6G monoclonal antibody, a specific marker for neutrophils, revealed a marked accumulation of neutrophils during atherosclerosis development. Neutrophils were observed in the lesion, attached to the cap, and in the arterial adventitia. In addition, at some sites, neutrophil accumulation colocalized with endothelial E-selectin expression. Immunofluorescence double staining with anti-myeloperoxidase and anti–Ly-6G antibodies demonstrated the presence of myeloperoxidase in atherosclerotic lesions and its colocalization with neutrophils. After introducing the high-fat diet, levels of circulating myeloperoxidase in plasma strongly increased, with a peak at 6 weeks and a subsequent decrease to almost normal levels after 16 weeks of diet.
Conclusions—
We here demonstrate for the first time the presence of neutrophils and myeloperoxidase in murine atherosclerotic lesions. As a major cell type in inflammatory responses the neutrophil may also be an important mediator in the development of atherosclerosis.
We identified myeloperoxidase-positive neutrophils in mouse atherosclerotic lesions. Although neutrophils were not detected in early lesions, they were abundantly present in more advanced stages. In addition, circulating myeloperoxidase levels were strongly increased by high-fat feeding of the mice. Therefore, neutrophils should be considered as a potential important cellular mediator in atherogenesis.
Chitin oligosaccharides inhibit oxidative stress in live cells
The aim of this research is to identify the cellular antioxidant effects of Chitin oligosaccharides inhibit oxidative stress in live cells
(NA-COS; Mw 229.21–593.12 Da) produced by acidic hydrolysis of crab chitin. The inhibitory effect of NA-COS on myeloperoxidase (MPO) activity in human myeloid cells (HL-60) and oxidation of DNA and protein in mouse macrophages (Raw 264.7) were identified. Furthermore, their direct radical scavenging effect by 2′,7′-dichlorofluorescein (DCF) intensity and intracellular glutathione (GSH) level were significantly increased in a time dependent manner, respectively. These results suggest that NA-COS act as a potent antioxidant in live cells.
ARTICLE
(NA-COS; Mw 229.21–593.12 Da) produced by acidic hydrolysis of crab chitin. The inhibitory effect of NA-COS on myeloperoxidase (MPO) activity in human myeloid cells (HL-60) and oxidation of DNA and protein in mouse macrophages (Raw 264.7) were identified. Furthermore, their direct radical scavenging effect by 2′,7′-dichlorofluorescein (DCF) intensity and intracellular glutathione (GSH) level were significantly increased in a time dependent manner, respectively. These results suggest that NA-COS act as a potent antioxidant in live cells.
ARTICLE
Myeloperoxidase levels are not associated with carotid atherosclerosis progression in patients with familial hypercholesterolemia
Introduction
myeloperoxidase (MPO), an antimicrobial enzyme of the innate immune system, has been proposed to exert a wide array of pro-atherogenic effects throughout all stages of the atherosclerotic process. In view of the potent anti-inflammatory effects of statins in vitro, we evaluated the impact of statin therapy on plasma MPO levels in patients with heterozygous familial hypercholesterolemia (FH), treated with either intensive or conventional lipid-lowering therapy. Furthermore, we evaluated the relation between myeloperoxidase (MPO)levels and atherosclerosis progression, as determined by intima media thickness (IMT).
Methods
We measured plasma MPO levels, lipoprotein profiles, high sensitivity-C-reactive protein (hs-CRP) as well as IMT of carotid artery segments in 122 FH patients at baseline and after 2-year treatment with atorvastatin 80mg or simvastatin 40mg QD.
Results
Baseline median myeloperoxidase (MPO)values were 147pM (interquartile range (IQR) 122–217) and 144pM (IQR 118–216) and these increased significantly to 221pM (IQR 144–290) and 255pM (IQR 152–324) during 2-year follow-up in both the atorvastatin 80mg and simvastatin 40mg group, respectively. There was no correlation between MPO levels and IMT progression, change in lipoproteins or hs-CRP.
Conclusion
In FH patients, statins do not prevent an increase in MPO levels during follow-up. Moreover, MPO levels are not associated with atherosclerosis progression in these patients.
myeloperoxidase (MPO), an antimicrobial enzyme of the innate immune system, has been proposed to exert a wide array of pro-atherogenic effects throughout all stages of the atherosclerotic process. In view of the potent anti-inflammatory effects of statins in vitro, we evaluated the impact of statin therapy on plasma MPO levels in patients with heterozygous familial hypercholesterolemia (FH), treated with either intensive or conventional lipid-lowering therapy. Furthermore, we evaluated the relation between myeloperoxidase (MPO)levels and atherosclerosis progression, as determined by intima media thickness (IMT).
Methods
We measured plasma MPO levels, lipoprotein profiles, high sensitivity-C-reactive protein (hs-CRP) as well as IMT of carotid artery segments in 122 FH patients at baseline and after 2-year treatment with atorvastatin 80mg or simvastatin 40mg QD.
Results
Baseline median myeloperoxidase (MPO)values were 147pM (interquartile range (IQR) 122–217) and 144pM (IQR 118–216) and these increased significantly to 221pM (IQR 144–290) and 255pM (IQR 152–324) during 2-year follow-up in both the atorvastatin 80mg and simvastatin 40mg group, respectively. There was no correlation between MPO levels and IMT progression, change in lipoproteins or hs-CRP.
Conclusion
In FH patients, statins do not prevent an increase in MPO levels during follow-up. Moreover, MPO levels are not associated with atherosclerosis progression in these patients.
Evaluation of the ameliorative effects of immunosuppressants on crescentic glomerulonephritis in SCG/Kj mice
The therapeutic efficacy of immunosuppressants for treating rapidly progressive glomerulonephritis (RPGN) with crescent formation remains controversial. SCG/Kj mice spontaneously develop RPGN-like symptoms, characteristic of crescentic glomerulonephritis and systemic small vessel vasculitis, associated with the presence of anti-neutrophil cytoplasmic antibodies (ANCA). We evaluated the “ameliorative”, not prophylactic, effects of immunosuppressive agents, deoxyspergualin (DSG), cyclophosphamide (CYC) and prednisolone (PDN), on RPGN in these mice. DSG at intraperitoneal doses of 3 and 6 mg/kg, CYC at an oral dose of 12 mg/kg, or PDN at an intraperitoneal dose of 120 mg/kg was administered once a day for 21 days to female mice “at the onset of hematuria”. A set of control SCG/Kj mice received only saline injections. DSG and CYC significantly prolonged survival, improved the proteinuria, hematuria and hyperuremia, and decreased the serum level of myeloperoxidase-ANCA. Moreover, DSG significantly suppressed the formation of crescents in glomeruli. PDN failed to affect any of the parameters. DSG might be useful for inducing remission in crescentic glomerulonephritis involved in RPGN.
ARTICLE
ARTICLE
Kinetic evidence for rapid oxidation of (–)-epicatechin by human myeloperoxidase
Apocynin has been reported to require dimerization by myeloperoxidase (MPO) to inhibit leukocyte NADPH oxidase. (–)-Epicatechin, a dietary flavan-3-ol, has been identified as a ‘prodrug’ of apocynin-like metabolites that inhibit endothelial NADPH oxidase activity and elevate the cellular level of nitric oxide. Since (–)-epicatechin has tentatively been identified as substrate of myeloperoxidase (MPO), we studied the one-electron oxidation of (–)-epicatechin by MPO. By using multi-mixing stopped-flow technique, we demonstrate that (–)-epicatechin is one of the most efficient electron donors for heme peroxidases investigated so far. Second order rate constants for the (–)-epicatechin-mediated conversion of MPO-compound I to compound II and compound II to resting enzyme were estimated to be 1.9 × 107 and 4.5 × 106 M−1 s−1, respectively (pH 7, 25 °C). The data indicate that (–)-epicatechin is capable of undergoing fast MPO-mediated one-electron oxidation.
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ARTICLE
Association of Major Depressive Disorder with Serum Myeloperoxidase and Other Markers of Inflammation: A Twin Study
Background
Major depressive disorder (MDD) has been linked to inflammation, but this association may be due to common precursors to both depression and inflammation. Myeloperoxidase (MPO) is an inflammatory enzyme produced by activated leukocytes that predicts risk of coronary heart disease. We sought to examine whether MPO and other markers of inflammation are associated with MDD and whether the association is confounded by genetic or other shared familial factors.
Methods
We examined 178 monozygotic and dizygotic middle-aged male twin pairs. We assessed MDD with the Structured Clinical Interview for DSM-IV. Blood markers of inflammation included MPO, interleukin-6, white blood cell count, C-reactive protein, necrosis factor (TNF)-α, the TNF-α soluble receptor II, and fibrinogen. Analyses were conducted in the overall sample and among 67 twin pairs discordant for MDD using mixed effects regression.
Results
Twins with a history of MDD had 32% higher levels of MPO (p < .0001); this difference persisted after adjusting for other risk factors. Among dizygotic MDD-discordant twin pairs, twins with MDD had 77% higher MPO than their brothers without MDD, after adjusting for other factors (p < .0001). In contrast, no significant association was found in monozygotic twins (p = .13). Similar, but weaker, associations were found between MDD and other inflammatory biomarkers.
Conclusions
Myeloperoxidase is a useful biomarker of immune activation in MDD. However, the association between inflammation and MDD is largely due to common genetic liability. Our results are consistent with the hypothesis that genes promoting inflammation are involved in the pathogenesis of MDD.
Major depressive disorder (MDD) has been linked to inflammation, but this association may be due to common precursors to both depression and inflammation. Myeloperoxidase (MPO) is an inflammatory enzyme produced by activated leukocytes that predicts risk of coronary heart disease. We sought to examine whether MPO and other markers of inflammation are associated with MDD and whether the association is confounded by genetic or other shared familial factors.
Methods
We examined 178 monozygotic and dizygotic middle-aged male twin pairs. We assessed MDD with the Structured Clinical Interview for DSM-IV. Blood markers of inflammation included MPO, interleukin-6, white blood cell count, C-reactive protein, necrosis factor (TNF)-α, the TNF-α soluble receptor II, and fibrinogen. Analyses were conducted in the overall sample and among 67 twin pairs discordant for MDD using mixed effects regression.
Results
Twins with a history of MDD had 32% higher levels of MPO (p < .0001); this difference persisted after adjusting for other risk factors. Among dizygotic MDD-discordant twin pairs, twins with MDD had 77% higher MPO than their brothers without MDD, after adjusting for other factors (p < .0001). In contrast, no significant association was found in monozygotic twins (p = .13). Similar, but weaker, associations were found between MDD and other inflammatory biomarkers.
Conclusions
Myeloperoxidase is a useful biomarker of immune activation in MDD. However, the association between inflammation and MDD is largely due to common genetic liability. Our results are consistent with the hypothesis that genes promoting inflammation are involved in the pathogenesis of MDD.
Plasma levels of myeloperoxidase are not elevated in patients with stable coronary artery disease
Background
Plasma and serum levels of myeloperoxidase (MPO), a redox-active hemoprotein released by polymorphonuclear neutrophils (PMN) upon activation, is now recognized as a powerful prognostic determinant of myocardial infarction in patients suffering acute coronary syndromes. However, there is limited information on whether systemic MPO levels are also elevated and of discriminating value in patients with stable coronary artery disease (CAD) representing different ethnic groups.
Methods
Plasma levels of MPO and traditional CAD risk factors were quantified in African American and Caucasian patients (n = 557) undergoing elective coronary angiography.
Results
MPO levels did not differ significantly between patients with or without CAD [421 pM (321, 533) vs. 412 pM (326, 500), p > 0.05]. MPO levels were similar across ethnicity and gender, and correlated positively with CRP and fibrinogen levels (r = 0.132, p = 0.002 and r = 0.106, p = 0.011, respectively).
Conclusion
In conclusion, plasma MPO levels were not elevated in patients with stable CAD, suggesting that systemic release of MPO is not a characteristic feature of asymptomatic CAD.
Lukas Kubalaa, d , Guijing Lub, Stephan Balduse, Lars Berglundb, f and Jason P. Eiserich
ARTICLE
Plasma and serum levels of myeloperoxidase (MPO), a redox-active hemoprotein released by polymorphonuclear neutrophils (PMN) upon activation, is now recognized as a powerful prognostic determinant of myocardial infarction in patients suffering acute coronary syndromes. However, there is limited information on whether systemic MPO levels are also elevated and of discriminating value in patients with stable coronary artery disease (CAD) representing different ethnic groups.
Methods
Plasma levels of MPO and traditional CAD risk factors were quantified in African American and Caucasian patients (n = 557) undergoing elective coronary angiography.
Results
MPO levels did not differ significantly between patients with or without CAD [421 pM (321, 533) vs. 412 pM (326, 500), p > 0.05]. MPO levels were similar across ethnicity and gender, and correlated positively with CRP and fibrinogen levels (r = 0.132, p = 0.002 and r = 0.106, p = 0.011, respectively).
Conclusion
In conclusion, plasma MPO levels were not elevated in patients with stable CAD, suggesting that systemic release of MPO is not a characteristic feature of asymptomatic CAD.
Lukas Kubalaa, d , Guijing Lub, Stephan Balduse, Lars Berglundb, f and Jason P. Eiserich
ARTICLE
MPO-ANCA Induces IL-17 Production by Activated Neutrophils in Vitro Via its Fc Region- and Complement-Dependent Manner
The elevation of serum anti-neutrophil cytoplasmic autoantibodies (ANCA) is significantly associated with the progression of some patients with systemic vasculitis. Especially, myeloperoxidase-specific ANCA (MPO-ANCA) play a pivotal role in the progression of systemic vasculitis including crescentic glomerulonephritis. Here we demonstrated that MPO-ANCA-activated neutrophils allow the local environment to differentiate Th17 cells through IL-6, IL-17A, and IL-23 production. We found a variety of elevated serum cytokines, especially IL-17A, in ANCA-mediated systemic vasculitis mice. Furthermore, activated peritoneal neutrophils in vitro also produced IL-17A and IL-23 in response to MPO-ANCA. Co-stimulation of fungal mannoprotein and complements significantly enhanced the MPO-ANCA-mediated IL-17A expression, but F(ab)′2 fragments of MPO-ANCA diminished the cytokine response. These results suggest that the activated neutrophils produce IL-17A and IL-23 in response to MPO-ANCA via their Fc-region and classical complement pathway, which initiate the first steps of chronic autoimmune inflammation by allowing the local environment to develop Th17-mediated autoimmunity.
Akiyoshi Hoshinoa, b, c, Tomokazu Nagaoc, d, Noriko Nagi-Miurae, Naohito Ohnoe, Masato Yasuharab, Kenji Yamamotoa, b, Toshinori Nakayamad and Kazuo Suzuki
Akiyoshi Hoshinoa, b, c, Tomokazu Nagaoc, d, Noriko Nagi-Miurae, Naohito Ohnoe, Masato Yasuharab, Kenji Yamamotoa, b, Toshinori Nakayamad and Kazuo Suzuki
A novel assay system for myeloperoxidase activity in whole saliva.
OBJECTIVES: The application of a novel assay system for the direct measurement of MPO (myeloperoxidase) activity in whole saliva .
DESIGN AND METHODS: The assay system employs a novel sensitive substrate from 3,3'-diaminobenzidine (DAB) and guaiacol in the presence of dapsone (4,4'-diaminodiphenylsulfone) to determine MPO activity in whole saliva using an original "sandwich" test-disk (DEAE-cellulose paper and cellulose chromatography paper). The saliva (0.1 mL) was directly applied to the sandwich test-disk, and then 0.1 mL of the substrate solution containing 1 mM dapsone in 0.3 M Tris-HCl buffer (pH 7.5) was added. After incubation for 30 min at room temperature, absorbance on the test-disk was measured at 460 nm with an optical analyzer.
RESULTS: The assay system was shown to distinguish MPO from salivary peroxidase in whole mixed saliva and was sensitive, easy and cheap. The assays revealed that MPO activity in whole saliva from subjects with periodontal disease was significantly higher than in saliva from healthy subjects. There was also a significant positive correlation between MPO activity and the probing depth of subgingival pockets (r=0.736, p<0.001).
CONCLUSIONS: These results indicate that this novel assay system for measurement of MPO is a useful technique for predicting the progression of periodontal disease.
Sakamoto W, Fujii Y, Kanehira T, Asano K, Izumi H.
Institute of Well Being, Fuji Women's University , 061-3204 Ishikari, Hokkaido, Japan; Serotec Laboratory, 069-0822 Ebetsu, Hokkaido, Japan. Clin Biochem. 2008 Jan 15
DESIGN AND METHODS: The assay system employs a novel sensitive substrate from 3,3'-diaminobenzidine (DAB) and guaiacol in the presence of dapsone (4,4'-diaminodiphenylsulfone) to determine MPO activity in whole saliva using an original "sandwich" test-disk (DEAE-cellulose paper and cellulose chromatography paper). The saliva (0.1 mL) was directly applied to the sandwich test-disk, and then 0.1 mL of the substrate solution containing 1 mM dapsone in 0.3 M Tris-HCl buffer (pH 7.5) was added. After incubation for 30 min at room temperature, absorbance on the test-disk was measured at 460 nm with an optical analyzer.
RESULTS: The assay system was shown to distinguish MPO from salivary peroxidase in whole mixed saliva and was sensitive, easy and cheap. The assays revealed that MPO activity in whole saliva from subjects with periodontal disease was significantly higher than in saliva from healthy subjects. There was also a significant positive correlation between MPO activity and the probing depth of subgingival pockets (r=0.736, p<0.001).
CONCLUSIONS: These results indicate that this novel assay system for measurement of MPO is a useful technique for predicting the progression of periodontal disease.
Sakamoto W, Fujii Y, Kanehira T, Asano K, Izumi H.
Institute of Well Being, Fuji Women's University , 061-3204 Ishikari, Hokkaido, Japan; Serotec Laboratory, 069-0822 Ebetsu, Hokkaido, Japan. Clin Biochem. 2008 Jan 15
Prognostic value of plasma myeloperoxidase concentration in patients with stable coronary artery disease
BACKGROUND: There are no studies yet on the usefulness of myeloperoxidase (MPO) as a prognostic tool in patients with stable coronary artery disease (CAD).
METHODS: The study included 382 patients with clinical and angiographic confirmation of stable CAD. Blood samples for MPO measurement were taken before angiography. Myeloperoxidase was determined using an enzyme immunoassay. The primary end point of the study was all-cause mortality.
RESULTS: Patients were categorized into 2 groups: the high-MPO group included patients in the third tertile of MPO levels (>75.0 microg/L; 127 patients), and the low-MPO group included patients in the first (<52.6 microg/L) and second tertiles (52.6-75.0 microg/L) of MPO levels (255 patients). The median follow-up was 3.5 [3.3-4.8] years. There were 35 deaths (9.2%) during the follow-up. The MPO concentration was 60.1 [47.0; 83.8] microg/L in survivors and 72.7 [54.8; 105.1] microg/L in nonsurvivors (P = .06). There were 17 deaths in the high-MPO level and 18 deaths in the low-MPO group: Kaplan-Meier estimates of mortality were 18.3% and 10.5% with an odds ratio of 1.96 (95% confidence interval [1.02-3.76], P = .04). The Cox proportional hazards model adjusting for correlates of mortality showed that plasma MPO was not an independent correlate of mortality (hazard ratio 1.06, 95% confidence interval [0.71-1.59], P = .77 for 1 SD increase in the log variable).
CONCLUSION: Although elevated plasma MPO concentration is associated with a more advanced cardiovascular risk profile, plasma MPO does not predict mortality independent of other cardiovascular risk factors in patients with stable CAD.
Am Heart J. 2008 Feb;155(2):356-60. Epub 2007 Dec 19,Faculty of Medicine, McGill University, Montreal, Quebec, Canada
METHODS: The study included 382 patients with clinical and angiographic confirmation of stable CAD. Blood samples for MPO measurement were taken before angiography. Myeloperoxidase was determined using an enzyme immunoassay. The primary end point of the study was all-cause mortality.
RESULTS: Patients were categorized into 2 groups: the high-MPO group included patients in the third tertile of MPO levels (>75.0 microg/L; 127 patients), and the low-MPO group included patients in the first (<52.6 microg/L) and second tertiles (52.6-75.0 microg/L) of MPO levels (255 patients). The median follow-up was 3.5 [3.3-4.8] years. There were 35 deaths (9.2%) during the follow-up. The MPO concentration was 60.1 [47.0; 83.8] microg/L in survivors and 72.7 [54.8; 105.1] microg/L in nonsurvivors (P = .06). There were 17 deaths in the high-MPO level and 18 deaths in the low-MPO group: Kaplan-Meier estimates of mortality were 18.3% and 10.5% with an odds ratio of 1.96 (95% confidence interval [1.02-3.76], P = .04). The Cox proportional hazards model adjusting for correlates of mortality showed that plasma MPO was not an independent correlate of mortality (hazard ratio 1.06, 95% confidence interval [0.71-1.59], P = .77 for 1 SD increase in the log variable).
CONCLUSION: Although elevated plasma MPO concentration is associated with a more advanced cardiovascular risk profile, plasma MPO does not predict mortality independent of other cardiovascular risk factors in patients with stable CAD.
Am Heart J. 2008 Feb;155(2):356-60. Epub 2007 Dec 19,Faculty of Medicine, McGill University, Montreal, Quebec, Canada
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