A myeloperoxidase precursor, promyeloperoxidase, is present in human plasma and elevated in cardiovascular disease patients

Myeloperoxidase (MPO)-derived oxidants have emerged as a key contributor to tissue damage in inflammatory conditions such as cardiovascular disease. Pro-myeloperoxidase (pro-MPO), an enzymatically active precursor of myeloperoxidase (MPO), is known to be secreted from cultured bone marrow and promyelocytic leukemia cells, but evidence for the presence of pro-MPO in circulation is lacking. In the present study, we used a LC-MS/MS in addition to immunoblot analyses to show that pro-MPO is present in human blood plasma. Furthermore, we found that pro-MPO was more frequently detected in plasma from patients with myocardial infarction compared to plasma from control donors. Our study suggests that in addition to mature MPO, circulating pro-MPO may cause oxidative modifications of proteins thereby contributing to cardiovascular disease

Maternal left ventricular function and adverse neonatal outcomes in women with cardiac disease.

PURPOSE: To evaluate the relationship between maternal left ventricular systolic function, utero-placental circulation, and risk of adverse neonatal outcomes in women with cardiac disease. METHODS: 119 women managed in the pregnancy heart clinic (2019-2021) were identified. Women were classified by their primary cardiac condition. Adverse neonatal outcomes were: low birth weight ( 20 weeks' gestation). Parameters of left ventricular systolic function (global longitudinal strain, radial strain, ejection fraction, average S', and cardiac output) were calculated and pulsatility index was recorded from last growth scan. RESULTS: Adverse neonatal outcomes occurred in 28 neonates (24%); most frequently in valvular heart disease (n = 8) and cardiomyopathy (n = 7). Small-for-gestational-age neonates were most common in women with cardiomyopathy (p = 0.016). Early pregnancy average S' (p = 0.03), late pregnancy average S' (p = 0.02), and late pregnancy cardiac output (p = 0.008) were significantly lower in women with adverse neonatal outcomes than in those with healthy neonates. There was a significant association between neonatal birth-weight centile and global longitudinal strain (p = 0.04) and cardiac output (p = 0.0002) in late pregnancy. Pulsatility index was highest in women with cardiomyopathy (p = 0.007), and correlated with average S' (p < 0.0001) and global longitudinal strain (p = 0.03) in late pregnancy. CONCLUSION: Women with cardiac disease may not tolerate cardiovascular adaptations required during pregnancy to support fetal growth. Adverse neonatal outcomes were associated with reduced left ventricular systolic function and higher pulsatility index. The association between impaired systolic function and reduced fetal growth is supported by insufficient utero-placental circulation.CEA is supported by a Medical Research Council New Investigator Grant (MR/T016701/1) and the NIHR Cambridge Biomedical Research Centr

Detection of mature MPO and pro-MPO in plasma using affinity-purification and immunblot analysis.

<p><b>A)</b> Plasma was spiked with MPO standard (10 nM) and HL60 cell lysate (containing 10 nM MPO) and subjected to affinity purification. Purified samples along with MPO, pro-MPO standards and HL-60 lysates were separated by 10% SDS/PAGE, transferred to PVDF and probed with MPO-specific antibody. <b>B)</b> Neutrophils (5x10⁶ cells/ml) were added back into plasma and then stimulated with CytB and FMLP for 30 min at 37°C. Neutrophils were centrifuged and cell free plasma MPO was subjected to affinity purification and analyzed as described in A. After the ECL fluorescence of blots was developed, a photograph of the blot showing the molecular weight markers was taken and aligned with the fluorescence image as indicated by the black line.</p