Personalized pathology test for Cardio-vascular disease: Approximate Bayesian computation with discriminative summary statistics learning.

Cardio/cerebrovascular diseases (CVD) have become one of the major health issue in our societies. But recent studies show that the present pathology tests to detect CVD are ineffectual as they do not consider different stages of platelet activation or the molecular dynamics involved in platelet interactions and are incapable to consider inter-individual variability. Here we propose a stochastic platelet deposition model and an inferential scheme to estimate the biologically meaningful model parameters using approximate Bayesian computation with a summary statistic that maximally discriminates between different types of patients. Inferred parameters from data collected on healthy volunteers and different patient types help us to identify specific biological parameters and hence biological reasoning behind the dysfunction for each type of patients. This work opens up an unprecedented opportunity of personalized pathology test for CVD detection and medical treatment.

The presence of modified nucleosides in extracellular fluids leads to the specific incorporation of 5-chlorocytidine into RNA and modulates the transcription and translation.

Myeloperoxidase (MPO) is able to promote several kinds of damage and is involved in mechanisms leading to various diseases such as atherosclerosis or cancers. An example of these damages is the chlorination of nucleic acids, which is considered as a specific marker of the MPO activity. Since 5-chlorocytidine has been recently shown in healthy donor plasmas, this study aimed at discovering if these circulating modified nucleosides could be incorporated into RNA and DNA and if their presence impacts the ability of enzymes involved in the incorporation, transcription, and translation processes. Experimentations, which were carried out in vitro with endothelial and prostatic cells, showed a large penetration of all chloronucleosides but an exclusive incorporation of 5-chlorocytidine into RNA. However, no incorporation into DNA was observed. This specific incorporation is accompanied by an important reduction of translation yield. Although, in vitro, DNA polymerase processed in the presence of chloronucleosides but more slowly than in control conditions, ribonucleotide reductase could not reduce chloronucleotides prior to the replication. This reduction seems to be a limiting step, protecting DNA from chloronucleoside incorporation. This study shows the capacity of transcription enzyme to specifically incorporate 5-chlorocytidine into RNA and the loss of capacity-complete or partial-of different enzymes, involved in replication, transcription or translation, in the presence of chloronucleosides. Questions remain about the long-term impact of such specific incorporation in the RNA and such decrease of protein production on the cell viability and function.

Impact of myeloperoxidase-LDL interactions on enzyme activity and subsequent posttranslational oxidative modifications of apoB-100.

Oxidation of LDL by the myeloperoxidase (MPO)-H2O2-chloride system is a key event in the development of atherosclerosis. The present study aimed at investigating the interaction of MPO with native and modified LDL and at revealing posttranslational modifications on apoB-100 (the unique apolipoprotein of LDL) in vitro and in vivo. Using amperometry, we demonstrate that MPO activity increases up to 90% when it is adsorbed at the surface of LDL. This phenomenon is apparently reflected by local structural changes in MPO observed by circular dichroism. Using MS, we further analyzed in vitro modifications of apoB-100 by hypochlorous acid (HOCl) generated by the MPO-H2O2-chloride system or added as a reagent. A total of 97 peptides containing modified residues could be identified. Furthermore, differences were observed between LDL oxidized by reagent HOCl or HOCl generated by the MPO-H2O2-chloride system. Finally, LDL was isolated from patients with high cardiovascular risk to confirm that our in vitro findings are also relevant in vivo. We show that several HOCl-mediated modifications of apoB-100 identified in vitro were also present on LDL isolated from patients who have increased levels of plasma MPO and MPO-modified LDL. In conclusion, these data emphasize the specificity of MPO to oxidize LDL.

Three-dimensional analysis of blood platelet spreading using digital holographic microscopy: a statistical study of the differential effect of coatings in healthy volunteers and dialyzed patients.

In cardiovascular disorders, the study of thrombocytes, commonly known as platelets, is highly important since they are involved in blood clotting, essential in hemostasis, and they can in pathological situations affect the blood circulation. In this paper, single deposited platelets are measured using interferometric digital holographic microscopy. We have shown that the average optical height of platelets is significantly lower in healthy volunteers than in dialyzed patients, meaning a better spreading. It demonstrates the great interest for assessing this parameter in any patients, and therefore the high potential of analyzing single spread platelets using digital holographic microscopy in fundamental research as well as a diagnostic tool in routine laboratories, for usual blood tests.

M2 Monocyte Polarization in Dialyzed Patients Is Associated with Increased Levels of M-CSF and Myeloperoxidase-Associated Oxidative Stress: Preliminary Results.

Cardiovascular diseases represent a major issue in terms of morbidity and mortality for dialysis patients. This morbidity is due to the accelerated atherosclerosis observed in these patients. Atherosclerosis is a chronic inflammatory disease characterized by key players such as monocytes, macrophages, or oxidized LDLs. Monocytes-macrophages are classified into subsets of polarized cells, with M1 and M2 macrophages considered, respectively, as pro- and anti-inflammatory. (1) Methods: The monocyte subsets and phenotypes were analyzed by flow cytometry. These data were completed by the quantification of plasma M-CSF, IL-8, CRP, Mox-LDLs, Apo-B, Apo-AI, chloro-tyrosine, and homocitrulline concentrations. The statistical differences and associations between two continuous variables were assessed using the Mann-Whitney U test and Spearman's correlation coefficient, respectively. (2) Results: Hemodialyzed patients showed a significant increase in their concentrations of CRP, M-CSF, and IL-8 (inflammation biomarkers), as well as chloro-tyrosine and homocitrulline (myeloperoxidase-associated oxidative stress biomarkers). Moreover, we observed a higher percentage of M2 monocytes in the plasma of hemodialysis patients as compared to the controls. (3) Conclusions: Our data suggest that oxidative stress and an inflammatory environment, which is amplified in hemodialysis patients, seems to favor an increase in the concentration of circulating M-CSF, therefore leading to an increase in M2 polarization among circulating monocytes.

Native and myeloperoxidase-oxidized low-density lipoproteins act in synergy to induce release of resolvin-D1 from endothelial cells.

BACKGROUND AND AIMS: Oxidation of native low-density lipoproteins (LDLs-nat) plays an important role in the development of atherosclerosis. A major player in LDL-nat oxidation is myeloperoxidase (MPO), a heme enzyme present in azurophil granules of neutrophils and monocytes. MPO produces oxidized LDLs called Mox-LDLs, which cause a pro-inflammatory response in human microvascular endothelial cells (HMEC), monocyte/macrophage activation and formation of foam cells. Resolvin D1 (RvD1) is a compound derived from the metabolism of the polyunsaturated fatty acid DHA, which promotes resolution of inflammation at the ng/ml level. METHODS: In the present study, we used liquid chromatography-mass spectrometry (LC-MS/MS) to investigate the synthesis of RvD1 and its precursors - 17(S)-hydroxy docosahexaenoic acid (17S-HDHA) and docosahexaenoic acid (DHA) - by HMEC, in the presence of several concentrations of Mox-LDLs, copper-oxidized-LDLs (Ox-LDLs), and native LDLs or in mouse plasma. The LC-MS/MS method has been validated and applied to cell supernatants and plasma to measure production of RvD1 and its precursors in several conditions. RESULTS: Mox-LDLs played a significant role in the synthesis of RvD1 and 17S-HDHA from DHA compared to Ox-LDLs. Moreover, Mox-LDLs and LDLs-nat acted in synergy to produce RvD1. In addition, different correlations were found between RvD1 and M1 macrophages, age of mice or Cl-Tyr/Tyr ratio. CONCLUSIONS: These results suggest that although Mox-LDLs are known to be pro-inflammatory and deleterious in the context of atherosclerosis, they are also able to induce a pro-resolution effect by induction of RvD1 from HMEC. Finally, our data also suggest that HMEC can produce RvD1 on their own.

Data on myeloperoxidase-oxidized low-density lipoproteins stimulation of cells to induce release of resolvin-D1.

This article present data related to the publication entitled "Native and myeloperoxidase-oxidized low-density lipoproteins act in synergy to induce release of resolvin-D1 from endothelial cells" (Dufour et al., 2018). The supporting materials include results obtained by Mox-LDLs stimulated macrophages and investigation performed on scavenger receptors. Linear regressions (RvD1 vs age of mice and RvD1 vs CL-Tyr/Tyr) and Data related to validation were also presented. The interpretation of these data and further extensive insights can be found in Dufour et al. (2018) [1].

Perceptive barriers to peritoneal dialysis implementation: an opinion poll among the French-speaking Belgian nephrologists.

Although peritoneal dialysis (PD) is recognized as an effective renal replacement therapy (RRT) alternative to haemodialysis (HD), its prevalence is around 15% in most of the industrialized countries. In the French-speaking part of Belgium, PD is clearly underused with a prevalence of 8.7% in 2009. The main objectives of this work were to evaluate the nephrologists' perceived obstacles to PD implementation and reflect on possible actions towards PD development. A computer-based 33-item questionnaire was sent by e-mail to all nephrologists affiliated to the French-speaking association. Among 120 adult nephrologists targeted by this inquiry, 97 completed the online questionnaire (response rate 80.8%). Among them, 29% had little experience with PD (treating less than five patients) and 39% reported no specific training with this modality of RRT. However, 88% of responders claimed PD prevalence should be around 20-25%. Half of the responders would choose PD as a first RRT option if they required RRT for themselves. The three main reasons given to the low prevalence of PD were an easy access to HD, patient refusal and lack of nephrologist motivation. Almost all the nephrologists insisted on the need for a dedicated nursing team delivering an effective educational programme and PD management and care. They believe that PD could and should be implemented in Belgium. Enhanced nephrologist motivation and training in PD were identified as predominant factors to be upgraded, as well as patient education programmes.

Simultaneous measurement of protein-bound 3-chlorotyrosine and homocitrulline by LC-MS/MS after hydrolysis assisted by microwave: application to the study of myeloperoxidase activity during hemodialysis.

A high degree of uremia is common in patients with end-stage renal disease and has been linked to the development of chronic inflammation and cardiovascular diseases. In conditions where transplantation is not possible, uremia can be reduced by hemodialysis although the repeated interventions have been implicated in loss of renal function, partially as a result of chronic inflammation and/or oxidative stress processes. In this context, it has been suggested that myeloperoxidase (MPO) can contribute to the oxidative stress during hemodialysis and to the cardiovascular risk. Protein damages due to MPO activity have never been assessed during hemodialysis although two of its reaction products, 3-chlorotyrosine and homocitrulline, are of interest. Indeed, the first one is a specific product of MPO activity and the formation of the second one could be catalyzed by MPO. In order to analyze these products in plasma proteins, a total hydrolysis method followed by liquid chromatography mass spectrometry analysis was developed. Different conditions of hydrolysis were tested and the optimized procedure was assessed for complete hydrolysis and artifactual chlorination. Finally, the method was used for analyzing 3-chlorotyrosine and homocitrulline in plasma proteins during a hemodialysis session in fifteen patients and data were related to measurements of MPO concentration and activity. Both increases in MPO activity and protein-bound 3-chlorotyrosine were observed, highlighting the involvement of MPO in oxidative stress during hemodialysis and further demonstrating the link between hemodialysis and cardiovascular diseases.