Pathogenic role of myeloperoxidase in acute pancreatitis

BACKGROUND:Myeloperoxidase(MPO)has been implicated in promoting tissue damage in various inflammatory diseases.However,MPO blood levels in relation to the severity of acute pancreatitis(AP)and its time-course have not been studied.The present study aimed to determine the role of MPO in AP.METHODS:We studied 86 patients with AP(48 patients with mild and 38 with severe pancreatitis)and 18 controls(volunteers).The relations of serum MPO levels to cytokine level,severity,and time-course of pancreatitis were studied.The serum level of MPO and cytokines were measured by MPO-EIA and cytokines ELISA,respectively.RESULTS:The highest level of MPO was noted at the first day in patients with severe AP.A decrease of MPO blood level occurred during the first three days in all patients with necrotizing pancreatitis.The development of pancreatitis-associated lung injury and purulent complications was accompanied by increased MPO levels.Administration of pentoxifylline significantly reduced the MPO blood level,which was clearly correlated with the levels of proinflammatory cytokines in the two groups of patients.CONCLUSIONS:The results of the present study showed the MPO blood level is dependent on the severity of AP and on cytokine blood levels.Pentoxifylline in the complex management of severe AP may improve the results of treatment.

Effects of the myeloperoxidase 463 gene polymorphisms on development of atrophy in H pylori infected or noninfected gastroduodenal disease

AIM： To investigate the relationship between myeloperoxidase polymorphisms as a host-related factor and atrophy caused by H pylori. METHODS： Our study enrolled 77 patients. Biopsy materials obtained during gastrointestinal endoscopies were evaluated for the presence of H pylori. Polymerase chain reaction-restriction fragment length polymorphism assay was used to characterize myeloperoxidase genothpes. RESULTS： Forty four patients （57.1%） were lip （＋） and 33 （42.9%） were Hp （-）. Sixty six （85.7%） had GG genotype, 10 （12.9%） had GA genotype and 1 （1.29%） had AA genotype. The change in atrophy in relation to neutrophil infiltration was significant in Hp （＋） patients （P = 0.0001）. The change in atrophy in relation to neutrophil infiltration in patients with GG genotype was significant （P = 0.002）. However, the change in atrophy in relation to neutrophil infiltration was not significiant in patients with Hp （＋） GG genotype （r = 0.066, P = 0.63）. CONCLUSION： Myeloperoxidase genotype is critical for development of atrophy in relation to the severity of inflammation. However, it is interesting to note that, H pylori does not show any additive effect on development of atrophy.

Early cardiopulmonary resuscitation on serum levels of myeloperoxidase,soluble ST2,and hypersensitive C-reactive protein in acute myocardial infarction patients

BACKGROUND Prompt and effective cardiopulmonary resuscitation(CPR)can promote the recovery of spontaneous circulation to some extent and can save patients’lives.The minimum target of cardiac resuscitation is the restoration of spontaneous circulation(ROSC).However,owing to prolonged sudden cardiac arrest,there is relatively high mortality within 24 h after cardiac resuscitation.Moreover,severe cerebral anoxia can deteriorate the prognosis of patients.Therefore,it is important to adopt an effective clinical evaluation of acute myocardial infarct(AMI)patients’prognosis after cardiac resuscitation for the purpose of prevention and management.AIM To investigate early CPR effects on human myeloperoxidase(MPO),soluble ST2(sST2),and hypersensitive C-reactive protein(hs-CRP)levels in AMI patients.METHODS In total,54 patients with cardiac arrest caused by AMI in our hospital were selected as the observation group,and 50 other patients with AMI were selected as the control group.The differences in serum levels of MPO,sST2,and hs-CRP between the observation group and the control group were tested,and the differences in the serum levels of MPO,sST2,and hs-CRP in ROSC and non-ROSC patients,and in patients who died and in those who survived,were analyzed.RESULTS Serum levels of MPO,sST2,hs-CRP,lactic acid,creatine kinase isoenzyme(CKMB),and cardiac troponin I(cTnI)were significantly higher in the observation group than in the control group(P<0.05).Serum levels of MPO,sST2,hs-CRP,lactic acid,CK-MB,and cTnI in the observation group were lower after CPR than before CPR(P<0.05).In the observation group,MPO,sST2,hs-CRP,lactic acid,CK-MB,and cTnI serum levels were lower in ROSC patients than in non-ROSC patients(P<0.05).MPO,sST2,hs-CRP,and lactic acid serum levels of patients who died in the observation group were higher than those of patients who survived(P<0.05).The areas under receiver operating characteristic curve predicted by MPO,sST2,hs-CRP,lactic acid,CK-MB,and cTnI were 0.616,0.681,0.705,0.704,0.702,and 0.656,respectively(P<0.05).The areas under receiver operating characteristic curve for MPO,SST2,hs-CRP,and lactic acid to predict death were 0.724,0.800,0.689,and 0.691,respectively(P<0.05).Logistic regression analysis showed that MPO,sST2,and hs-CRP were the influencing factors of ROSC[odds ratios=1.667,1.589,and 1.409,P<0.05],while MPO,sST2,hs-CRP,and lactic acid were the influencing factors of death(odds ratios=1.624,1.525,1.451,and 1.365,P<0.05).CONCLUSION Serum levels of MPO,sST2,hs-CRP,and lactic acid have a certain value in predicting recovery and prognosis of patients with ROSC.

FT Ⅰ, a novel positive myeloid-lineage-speciflc transcription regulatory element within the mouse myeloperoxidase gene enhancer, En 1

FT Ⅰ (AAAAGGGGAAGCAGAG), a poly purine ele-ment within the myloid-lineage specific enhancer (En 1) of the mouse myeloperoxidase gene [1, 2] has been fur-ther characterised. 1, FT Ⅰ functions as a myeloid-lineage specific transcription regulatory element; 2, WEHI 3BD+ cells have higher binding activity to FT Ⅰ and express the proteins which could form the unique DNA-protein com-plex(es) of FT Ⅰ;. 3, The essential sequence for the specific DNA-protein interactions of FT Ⅰ is AAAAGGGGAAGC; 4, South-western analysis in conjunction with the compe-tition assay of the proteins binding to FT Ⅰ, has revealed a 28 kd protein in WEHI 3BD+ cells that displays the properties of the putative transcription factor which acts through FT Ⅰ. These new findings have demonstrated both the functional myeloid-lineage specificity and the novelty of FT Ⅰ.

Myeloperoxidase and High-Sensitivity C-Reactive Protein for Predicting Major Adverse Cardiovascular Events in Patients with Coronary Heart Disease

Background: Research has shown that high-sensitivity C-reactive protein (hs-CRP) is a major inflammatory marker for prediction of acute coronary syndrome (ACS). Myeloperoxidase (MPO) also plays an important role in atherosclerosis initiation and development. In present study, the major adverse cardiovascular events (MACEs) of patients with coronary heart disease (CHD) were investigated. Methods: MPO, hs-CRP and ACS-related risk factors from 201 ACS (78 AMI and 123 UAP) and 210 non-ACS (84 SAP and 126 non-CHD) patients confirmed by coronary angiography were detected, and the data were analyzed with receiver operating characteristic (ROC) curve and Spearman’s correlation coefficients. MACEs of 285 CHD patients were investigated during the 4-year period follow-up from March 2010 to May 2014. Results: The areas under ROC curve for diagnosing ACS were 0.888 (95% CI 0.843 - 0.933) for MPO, and 0.862 (95% CI 0.815-0.910) for hs-CRP, respectively. There were significantly correlations between MPO and hs-CRP in both ACS and non-ACS groups. Regarding to ACS patients, both MPO and hs-CRP were positively correlated with BMI, TC, TG, LDL-C and Hcy. Prospective study demonstrated that the incidences of MACEs associated significantly with elevated MPO baseline level (yes vs no, OR 7.383, 95% CI 4.095 - 13.309) and high hs-CRP baseline level (yes vs no, OR 4.186, 95% CI 2.469 - 7.097) in CHD patients. Conclusions: The present study provides the epidemiological evidence that elevated baseline MPO and hs-CRP levels are both valuable predictors of MACEs in CHD patients. MPO and hs-CRP would prompt the progression of atherosclerosis and development from SAP to ACS.

Association of the myeloperoxidase ^(468)G→K polymorphism with gastric inflammation and duodenal ulcer risk

AIM: To elucidate the relations between the myeloperoxidase ^(-468)G→a polymorphism and the development of duodenal ulcer (DU), and to investigate the impacts of this host genetic polymorphism on the histopathological features of Helicobacter pylori (H py/ori)-related gastritis. METHODS: In a case-control study of 115 consecutive DU patients and 182 controls, the myeloperoxidase ^(-468)G→A polymorphism was genotyped. Additionally, gastric mucosal changes were examined according to the updated Sydney System. RESULTS: The two study groups differed in the distributions of myeloperoxidase genotypes (P=0.008). All six individuals carrying myeloperoxidase A/A genotypes were in the DU group. The carriage of myeloperoxidase allele A and H pylori infection were associated with an increased risk of DU with odds ratios (OR) of 2.3 and 5.8, respectively. The combined risk of the carriage of myeloperoxidase allele A and H pylori infection for DU was 8.7 (95% CI, 3.5-21.8). In the H pylori-infected individuals, allele A carriers displayed higher bacterial density scores (P=0.04) in the antrum than did non-carriers. CONCLUSION: This work verifies for the first time the association of myeloperoxidase ^(-468)G→A polymorphism with antral H pylori density and DU disease. The mechanisms underlying this genetic polymorphism in developing DU disease merit further investigations.

Myeloperoxidase: a new target for the treatment of stroke?

Myeloperoxidase is an important inflammatory factor in the myeloid system,primarily expressed in neutrophils and microglia.Myeloperoxidase and its active products participate in the occurrence and development of hemorrhagic and ischemic stroke,including damage to the blood-brain barrier and brain.As a specific inflammatory marker,myeloperoxidase can be used in the evaluation of vascular disease occurrence and development in stroke,and a large amount of experimental and clinical data has indicated that the inhibition or lack of myeloperoxidase has positive impacts on stroke prognosis.Many studies have also shown that there is a correlation between the overexpression of myeloperoxidase and the risk of stroke.The occurrence of stroke not only refers to the first occurrence but also includes recurrence.Therefore,myeloperoxidase is significant for the clinical evaluation and prognosis of stroke.This paper reviews the potential role played by myeloperoxidase in the development of vascular injury and secondary brain injury after stroke and explores the effects of inhibiting myeloperoxidase on stroke prognosis.This paper also analyzes the significance of myeloperoxidase etiology in the occurrence and development of stroke and discusses whether myeloperoxidase can be used as a target for the treatment and prediction of stroke.

Urinary Myeloperoxidase to Creatinine Ratio as a New Marker for Diagnosis of Urinary Tract Infection

Objective To determine whether urinary myeloperoxidase to creatinine ratio(MCR) can serve as a marker for diagnosis of urinary tract infection(UTI).Methods Patients suspected of UTI were consecutively enrolled and further divided into the culture positive and the sterile groups according to urine culture results. Subsequently, MCR, white blood cell(WBC) and bacteria in the urinary samples from patients were detected and compared between the two groups.Results Finally, 253 patients were enrolled including 157 urine culture positive patients and 96 urine culture negative patients(sterile group). After logarithmic transformation in 2 as the base, the MCR, WBC, and bacteria were separately presented as log_2^(MCR), log_2^(WBC)(quantitative), and logbacteria2. The values of log_2^(MCR)(8.6±2.5 vs. 5.4±1.5, t=-12.453, P=0.001), log_2^(WBC)(quantitative)(8.0±2.5 vs. 5.2±1.8, t=-10.332, P=0.001), logbacteria2(11.4±2.5 vs. 8.2±2.8, t=-9.297, P=0.001) and WBC(semi-quantitative) [2(interquartile range 1, 3) vs. 1(interquartile range 0.5, 1), Z=-7.580, P=0.001] showed significant difference between the urine culture positive group and the sterile group. Among the urine culture positive group, the values of log_2^(MCR) of the gram positive and gram negative subgroups were 7.2±2.5 and 9.0±2.4(t=4.016, P=0.001), respectively. The correlation between log_2^(MCR) and log_2^(WBC)(quantitative), log_2^(bacteria), WBC(semi-quantitative) was 0.708(Pearson correlation, P=0.001), 0.381(Pearson correlation, P=0.001), and 0.606(Spearman correlation, P=0.001), respectively.Conclusions MCR is positively correlated with WBC counts and could be ser ved as a promising biomarker for diagnosis of UTI. MCR could be even used for initial inference of infectious bacteria types of UTI.

Clinical Significance of a Myeloperoxidase Gene Polymorphism and Inducible Nitric Oxide Synthase Expression in Cirrhotic Patients with Hepatopulmonary Syndrome

The clinical significance of a myeloperoxidase (MPO) gene polymorphism and inducible nitric oxide synthase (iNOS) expression in cirrhotic patients with hepatopulmonary syndrome (HPS) was explored. Enrolled subjects were divided into three groups according to their disease/health conditions: the HPS group (cirrhotic patients with HPS; n=63), the non-HPS group (cirrhotic patients without HPS; n=182), and the control group (healthy subjects without liver disease; n=35). The distribution of the MPO–463 G/A genotype and its relationship with iNOS expression in a typical cell block from ascitic fluid were detected by immunohistochemistry and polymerase chain reaction-restricted fragment length polymorphism analysis (PCR-RFLP). In the HPS group, the partial pressure of oxygen in blood and ascitic fluid was significantly decreased (8.95±1.58 kPa and 6.81±0.95 kPa, respectively; both P<0.01), while the partial pressure of carbon dioxide significantly increased (4.62±0.20 kPa and 5.92±0.45 kPa, respectively; P<0.01). MPO and iNOS levels were significantly increased in the HPS group as compared with the non-HPS group. These increases were even more remarkable in ascitic fluid (41.36±11.62 and 13.23±4.81 μg/L; 10.27± 3.20 and 4.95±1.12 μg/L) than in blood (16.66±5.24 and 4.87±1.73 μg/L; 5.79±2.31 and 2.35±0.84 μg/L). The distribution of the MPO genotypes GG, GA, and AA were 76.2%, 22.2% and 1.6% in the HPS group, and 57.7%, 37.9% and 4.4% in the non-HPS group (P<0.05). The expression of iNOS was significantly higher in patients with the G alleles (G/G and G/A) (61.54%, 48/78) than in patients with A alleles (G/A and A/A) (38.46%, 30/78) (P<0.01). It was suggested that the expression levels of iNOS and MPO were correlated with HPS-induced hypoxemia. The MPO-463 G/A mutation might be a protective factor that prevents the development of HPS. The MPO might be involved in the regulation of iNOS expression. In humans, MPO pathways, the iNOS/NO system, and their interaction might have an impact on the occurrence and development of HPS.

CLINICAL AND PATHOLOGICAL MANIFESTATI-ONS OF PATIENTS WITH ANTINEUTROPHIL CYTO-PLASMIC AUTOANTIBODIES DIRECTED AGA INST PROTEINASE 3 OR MYELOPEROXIDASE

To compare the clinical and pathological manifestations of patients with antineutrophil cytoplasmic autoantibodies (ANCA) directed against proteinas e 3 (anti PR3) or myeloperoxidase (anti MPO). Methods. One hundred and forty patients with ANCA were detected for anti PR3 a nd anti MPO by ELISA. The clinical features at presentation, histopathological characteristics and outcome of all patients who were tested positive for anti P R3 or anti MPO were analysed.Results. In anti PR3 group (n=21), 16 cases (76.2%) had systemic vasculitis , in which Wegener’s granulomatosis prevailed (13 cases, 61.9%). In anti MPO g roup (n=31), 19 cases (61.3%) were diagnosed as systemic vasculitis and 12 case s (38.7%) as microscopic angiitis. For vasculitic patients with anti PR3 and a nti MPO, the disease duration at diagnosis was 9.6±2.0m and 4.4±0.9m respecti vely, P< 0.05;vasculitis activity index (BVAS) and mean number of affected organ were 22.5±2.1, 5.0±0.4 and 25.1±1.7, 4.8±0.4 respectively, P >0.05;upper r espiratory tract, eye and joint involvements were 11(68.8%), 7(43.8%), 11(68.8 %) and 7(36.8%), 2(10.5%), 5(26.3%) respectively, P< 0.05.Although there was no statistical difference in renal involvement between these two groups, patien ts with serum creatine >500 μmol/L were more commonly seen in anti MPO group t han in anti PR3 group, which were 8(42.1%) and 2(12.5%) respectively, P< 0.05 . Ten relapses were seen in anti PR3 group and only 2 in anti MPO group, but t he acute mortality rate in anti MPO group (5/19, 27.4%) was much higher than t hat in anti PR3 group (1/16, 6.3%). Conclusions. Anti PR3 and anti MPO occurred mainly in systemic vasculitis. A large divergence was seen in the disease spectrum between patients with anti PR 3 and those with anti MPO. In particular, upper respiratory tract, eye and join t involvements, granuloma formation and relapse were more prominent in anti PR3 patients. By contrast, the anti MPO patients had a more acute disease onset, m ore rapid progressive renal involvement and a higher acute mortality rate.

Cardiac Myeloperoxidase Activity Is Elevated in Hypertensive Pregnant Rats

Myeloperoxidase（MPO） is released from activated neutrophils. The inflammation in preeclampsia was found to be associated with endothelial dysfunction. We hypothesized that cardiac and circulating MPO levels are elevated in hypertensive pregnancy. Systolic and diastolic blood pressure and heart rate were measured on pregnancy days 14, 16, 18 and 20 in normal pregnant and hypertensive pregnant rats. Left and right ventricle weights, the number of viable fetuses, litter size, fetal and placenta weights were recorded on gestational day 21. Circulating and cardiac MPO activities, soluble fms-like tyrosine kinase-1（sFlt-1） and vascular endothelial growth factor（VEGF） and nitric oxide（NO） were detected. The results showed increases in cardiac（left, but not right ventricle） and circulating MPO activities, and concomitantly lower number of viable fetuses, litter size, and fetal and placenta weights, and decreases in NO in hypertensive pregnant rats. Also, the increases in circulating sFlt-1 and VEGF were found in hypertensive pregnant group. In conclusion, maternal and fetal detrimental changes along with increases in circulating sFlt-1 and VEGF in hypertensive pregnancy may be associated with increases in cardiac and circulating MPO activities, confirming the causative role of inflammatory response in preeclampsia.

Severity evaluation value of serum myeloperoxidase content detection in patients with acute coronary syndrome

Objective:To analyze the value of serum myeloperoxidase content detection for severity evaluation in patients with acute coronary syndrome.Methods: Acute coronary syndrome (ACS) group included 32 cases, stable angina pectoris (SAP) group included 46 cases, levels of myeloperoxidase (MPO), inflammatory factors and lipid metabolism indexes in serum were compared, coronary echocardiography blood flow parameters were detected, and the correlation between MPO and ACS severity-associated indexes was further analyzed.Results:MPO content in serum of ACS group was significantly higher than those of SAP group and control group;inflammatory factors hs-CRP, IL-6, MCP-1 and LP-PLA2 content in serum were higher than those of SAP group and control group while IL-13 and TGFβ content were lower than those of SAP group and control group;lipid metabolism indexes TC, TG, LDL-C, ApoAI and ApoB content in serum were higher than those of SAP group and control group while HDL-C content was lower than that of SAP group and control group;ultrasonic coronary blood flow parameters SPV, DPV, A, CFVR and CTVⅠ levels were lower than those of SAP group and control group. The serum MPO content in patients with ACS was directly correlated with the content of inflammatory factors and lipid metabolism indexes as well as thelevels of coronary blood flow parameters.Conclusions:Serum MPO content in patients with ACS is directly correlated with the disease severity, and can be used as a reliable index for long-term guide of treatment and prediction of treatment outcome.

Effects of low molecular weight heparin-superoxide dismutase conjugate on serum levels of nitric oxide,glutathione peroxidase,and myeloperoxidase in a gerbil model of cerebral ischemia/reperfusion injury

BACKGROUND： Several studies have demonstrated that low molecular weight heparin-superoxide dismutase （LMWH-SOD） conjugate may exhibit good neuroprotective effects on cerebral ischemia/reperfusion injury though anticoagulation, decreasing blood viscosity, having anti-inflammatory activity, and scavenging oxygen free radicals. OBJECTIVE： To investigate the intervention effects of LMWH-SOD conjugate on serum levels of nitric oxide （NO）, glutathione peroxidase （GSH-Px）, and myeloperoxidase （MPO） following cerebral ischemia/reperfusion injury. DESIGN, TIME AND SETTING： A randomized, controlled, and neurobiochemical experiment was performed at the Institute of Biochemical Pharmacy, School of Pharmaceutical Sciences, Shandong University between April and July 2004. MATERIALS： A total of 60 Mongolian gerbils of either gender were included in this study. Total cerebral ischemia/reperfusion injury was induced in 50 gerbils by occluding bilateral common carotid arteries. The remaining 10 gerbils received a sham-operation （sham-operated group）. Kits of SOD, NO, and MPO were sourced from Nanjing Jiancheng Bioengineering Institute, China. LMWH, SOD, and LMWH-SOD conjugates were provided by Institute of Biochemistry and Biotechnique, Shandong University, China. METHODS： Fifty successful gerbil models of total cerebral ischemia/reperfusion injury were evenly randomized to five groups： physiological saline, LMWH-SOD, SOD, LMWH ＋ SOD, and LMWH. At 2 minutes prior to ischemia, 0.5 mL/65 g physiological saline, 20 000 U/kg LMWH-SOD conjugate, 20 000 U/kg SOD, a mixture of SOD （20 000 U/kg） and LMWH （LMWH dose calculated according to weight ratio, LMWH： SOD = 23.6：51）, and LMWH （dose as in the LMWH ＋ SOD group） were administered through the femoral artery in each above-mentioned group, respectively. MAIN OUTCOME MEASURES： Serum levels of NO, MPO, and GSH-Px. RESULTS： Compared with 10 sham-operated gerbils, the cerebral ischemia/reperfusion injury gerbils exhibited decreased serum levels of GSH-Px and increased serum levels of NO and MPO （P 〈 0.01）. The serum level of GSH-Px was significantly upregulated in all groups, in particular in the LMWH-SOD group （P 〈 0.01）, compared with the physiological saline group （P 〈 0.05-0.01）. Following medical treatment, serum levels of NO and MPO were significantly downregulated in all groups, in particular in the LMWH-SOD group （P 〈 0.01）. Serum levels of GSH-Px, NO, and MPO in the LMWH-SOD group were close to those in the sham-operated group （P 〉 0.05）. CONCLUSION： In cerebral ischemia/reperfusion injury, LMWH-SOD conjugate exhibits stronger neuroprotective effects on free radical scavenging, inflammation inhibition, and cytotoxicity inhibition than simple or combined application of LMWH and SOD by downregulating NO and MPO levels and upregulating the GSH-Px level.

Serum Myeloperoxidase Level in Systemic Lupus Erythematosus

SYSTEMIC lupus erythematosus （SLE） is a systemicautoimmune disease. Several mechanismshave been put forward as underlying the loss ofself-tolerance and development of organdysfunction, such as genetic, environmental, hormonal andimmunoregulatory factors.

Clinical correlation between myeloperoxidase and acute coronary syndrome

Objective To study whether myeloperoxidase (MPO) can provide prognostic information in patients with acute coronary syndromes (ACS). Methods The study population consisted of 274 consecutive patients with ACS. All patients underwent coronary angiography which showed significant coronary artery disease and blood samples were collected at admission. Follow-ups were scheduled at 1, 3, and 6 months.The end point included cardiac death, acute myocardial infarction (MI), percutaneous or surgical revascularization. Results Patients with elevated MPO serum levels (MPO ≥ 72.2 AUU/L) were more likely to have diabetics and had a history of coronary events. Kaplan-Meier event rate curves with accumulative incidence of end point at 6-month follow-up in the MPO ≥ 72.2 AUU/L group was significantly higher than in MPO<72.2 AUU/L group. Conclusions MPO may be a powerful predictor of adverse outcome in patients with ACS.(J Geriatr Cardiol 2007;4:209-212)

Role of Lactic Acid Bacteria-Myeloperoxidase Synergy in Establishing and Maintaining the Normal Flora in Man

Lactic acid bacteria (LAB) are incapable of cytochrome synthesis and lack the heme electron transport mechanisms required for efficient oxygen-based metabolism. Consequently, LAB redox activity is flavoenzyme-based and metabolism is fermentative, producing lactic acid, and in many cases, hydrogen peroxide (H2O2). Despite this seeming metabolic limitation, LAB dominate in the normal flora of the mouth, vagina and lower gastrointestinal tract in man. Myeloperoxidase (MPO) is produced by the neutrophil leukocytes and monocytes that provide the innate phagocyte defense against infecting pathogens. MPO is unique in its ability to catalyze the H2O2-dependent oxidation of chloride (Cl-) to hypochlorite (OCl-). In turn, this OCl- directly reacts with a second H2O2 to produce singlet molecular oxygen (), a metastable electronic excitation state of oxygen with a microsecond lifetime that restricts its combustive reactivity within a submicron radius of its point of generation. Each day a healthy human adult produces about a hundred billion neutrophils containing about 4 femtograms MPO per neutrophil. Inflammatory states and G-CSF treatment increase both neutrophil production and the quantity of MPO per neutrophil. After a short circulating lifetime, neutrophils leave the blood and migrate into body spaces including the mouth, vagina, urinary tract, and gastrointestinal tract. Greater than a hundred thousand neutrophils are lavaged from the mouths of healthy humans;the quantity lavaged is proportional to the blood neutrophil count. MPO selectively and avidly binds to most Gram-positive and all Gram-negative bacteria tested, but LAB do not show significant MPO binding. Neutrophils migrating to normal flora sites release MPO into the LAB-conditioned milieu containing adequate acidity and H2O2 to support extra-phagocyte MPO microbicidal action. In combination, LAB plus MPO exert a potent synergistic microbicidal action against high MPO-binding microbes. This LAB-MPO synergy provides a mechanism for the establishment and maintenance of LAB in the normal flora of man.

Serum myeloperoxidase level is increased in heavy smokers

Raised myeloperoxidase (MPO) serum levels are associated with endothelial dysfunction and cigarette smoking is a risk factor for cardiovascular diseases. Since myocardial infarction is associated with leukocytosis and smokers present increased levels of neutrophils, here we hypothesized that the levels of serum MPO in smokers could be also raised. We carried out a study on sixty eight adult healthy volunteers. The control group consisted of thirty four non-smokers and the test group was thirty four heavy smokers. The hemogram, interleukin-8 (IL-8) and MPO serum levels were measured. Neutrophil, monocyte and lymphocyte counts were higher

Association between Plasma Myeloperoxidase and Free 3-Nitrotyrosine Levels in Patients with Coronary Artery Disease

Objective: Myeloperoxidase (MPO) is an inflammatory enzyme that is mainly released by activated neutrophils and monocytes. 3-nitrotyrosine (NT) is a stable inflammatory end product of MPO that is produced through nitrosylation of free and protein-bound tyrosines. Determination of the exact levels of free NT is technically a challenging matter. Also, there is limited information about the relationship between MPO and free NT levels and elevation of them in the plasma of patients with coronary artery disease (CAD). Therefore, we sought to determine the exact level of plasma free NT with a simple and exquisite technique in CAD patients. Methods: This study included 50 stable angina, 50 unstable angina patients, and 50 control subjects. Plasma MPO concentration was measured with an immunoassay method. Plasma free NT level was determined by a modified HPLC-fluorescence method. Lipid profile, high sensitivity C-reactive protein (hsCRP) and other clinical risk factors of patients were also assigned. Results: Plasma level of free NT was efficiently measured by the HPLC-fluorescence method. Plasma levels of MPO and NT were significantly higher in patients with stable and unstable CAD than in control subjects (P < 0.001). There was a significant correlation between the two substances in CAD patients (P < 0.001). Conclusions: We determined plasma free NT levels with a sensitive HPLC-fluorescence method with some modifications in a clinical scale. Plasma levels of MPO and NT were profoundly elevated in CAD patients. The significant relationships of the two substances and elevation of them may have useful clinical implication in patients with stable and unstable CAD.

Validity of QRS Configuration and Myeloperoxidase Level as Determinants of CAD Severity and Prognosis in Patients with STEMI

Background: Terminal QRS distortion and fragmentation (fQRS) with elevated myeloperoxidase (MPO) were linked to poor cardiovascular outcomes in acute coronary syndrome. We aimed to investigate these parameters in early prediction of coronary artery disease severity based on SYNTAX score and in-hospital adverse events in STEMI patients. Methods: A total of 215 patients with first STEMI admitted for primary PCI were included in the study. They were divided according to the admission ECG into group I with QRS distortion or fQRS, group II with combined QRS distortion and fQRS, and group III without QRS distortion or fQRS. Myeloperoxidase and troponin I levels, ST resolution ratio, left ventricular EF%, and severity of coronary artery lesions using SYNTAX risk score were measured. Results: MPO level, SYNTAX score, and in-hospital mortality were higher in group I and II and were higher in group II compared to group I. By regression analysis, QRS distortion, fQRS, and MPO > 412 ng/ml were independent predictors of both CAD severity and in-hospital mortality. DM was an independent predictor of CAD severity (OR: 2.851, P 0.012) while high SYNTAX score was an independent predictor of in-hospital mortality (OR: 6.113, P 0.001). Adding MPO level to any QRS configuration pattern increased predictive value for the detection of CAD severity that was more evident in the combined QRS distortion and fragmentation. Conclusion: Terminal QRS distortion, fragmentation, or combined QRS distortion and fragmentation have a significant value in predicting in-hospital adverse events and CAD severity as assessed by SYNTAX score in association with plasma myeloperoxidase level in STEMI patients. Combined QRS distortion and fragmentation, in spite less common, could be more helpful for early risk stratification and management.

Introducing a Rapid and Safe Method for Myeloperoxidase Staining

Background: Myeloperoxidase staining is used to differentiate leukemias since several decades. Despite implementation of flow cytometric, cytogenetic and molecular techniques for identification of leukemic blasts, histochemical stains such as myeloperoxidase stain are persistently used for better classification of leukemias. The myeloperoxidase staining is a time consuming and hazardous procedure. The present report describes a sensitive, rapid and easy method for assessment of peroxidase activity. Materials and Methods: Bone marrow aspiration slides were stained with Dako product: Code number: K3467 containing DAB chromogen (3,3-diaminobenzidine in chromogen solution) and substrate buffer (Imidasole-HCL buffer, PH 7.5 containing hydrogen peroxide and an anti microbial agent) in a rapid procedure taking only ten minutes time. The staining needs no material preparation steps. Neutrophils in the slide are taken as positive control or another normal smear was costained to be used as control. All cases were followed up with flow cytometry and cytogenetic studies. Result: The reaction product of this stain is brown and granular. Promyelocytes and myelocytes are the most strongly staining cells with positive (primary) granules. Lymphoblasts are negative. The result of classification of leukemias with this technique was in concordance with flow cytometric immunophenotyping. Discussion: Many practical techniques have been described using benzidine as an indicator for myeloperoxidase staining. Benzidine is a carcinogenic material and its usage is severely restricted in laboratory. Formerly we prepared requisite materials for myeloperoxidase staining by hazardous ways (boiling), but we decided to apply ready to use 3,3-diaminobenzidine (DAB), which is used in final step of immunohistochemistry stains. Conclusion: Use of 3,3-diaminobenzidine (DAB) is highly recommended for myeloperoxidase staining, while the result is extraordinary and fully compatible with flow cytometry and the method is safe and rapid.