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.

Anticoagulation With an Inhibitor of Factors XIa and XIIa During Cardiopulmonary Bypass.

BACKGROUND: Exposure of blood to polyanionic artificial surfaces, for example, during cardiopulmonary bypass (CPB), induces a highly procoagulant condition requiring strong anticoagulation. Unfractionated heparin (UFH) is currently used during CPB but can lead to serious bleeding complications or development of a hypercoagulable state culminating in life-threatening thrombosis, highlighting the need for safer antithrombotics. Ixodes ricinus contact phase inhibitor (Ir-CPI) is a protein expressed by I. ricinus ticks, which specifically inhibits both factors XIIa and XIa, 2 factors contributing to thrombotic disease while playing a limited role in hemostasis. OBJECTIVES: This study assessed the antithrombotic activity of Ir-CPI in animal contact phase-initiated thrombosis models, including CPB. The safety of Ir-CPI also was evaluated. METHODS: The authors evaluated the antithrombotic activity of Ir-CPI by using in vitro catheter-induced clotting assays and rabbit experimental models of catheter occlusion and arteriovenous shunt. During CPB with cardiac surgery in sheep, the clinical applicability of Ir-CPI was investigated and its efficacy compared to that of UFH using an uncoated system suitable for adult therapy. Taking advantage of the similar hemostatic properties of pigs and humans, the authors performed pig liver bleeding assays to evaluate the safety of Ir-CPI. RESULTS: Ir-CPI prevented clotting in catheter and arteriovenous shunt rabbit models. During CPB, Ir-CPI was as efficient as UFH in preventing clot formation within the extracorporeal circuit and maintained physiological parameters during and post-surgery. Unlike UFH, Ir-CPI did not promote bleeding. CONCLUSIONS: Preclinical animal models used in this study showed that Ir-CPI is an effective and safe antithrombotic agent that provides a clinically relevant approach to thrombosis prevention in bypass systems, including highly thrombogenic CPB.

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].

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.

Myeloperoxidase-Oxidized LDLs Enhance an Anti-Inflammatory M2 and Antioxidant Phenotype in Murine Macrophages.

Macrophages and oxidized LDLs play a key role in atherogenesis but their heterogeneity has been neglected up to now. Macrophages are prone to polarization and subsets of polarized macrophages have been described in atheromas. LDLs can be oxidized not only chemically by copper (Ox-LDLs) but also enzymatically by myeloperoxidase (MpOx-LDLs) resulting in oxidized LDLs poor in lipid peroxides. The effects of physiologically relevant myeloperoxidase-oxidized LDLs on macrophage polarization or on polarized macrophages remain largely unknown. In this study, the effects of LDLs on macrophage polarization were investigated by monitoring the expression of M1 and M2 genes following stimulation with native LDLs, Ox-LDLs, or MpOx-LDLs in RAW 264.7 cells. Except for MRC1, which is induced only by Ox-LDLs, MpOx-LDLs induced an overexpression of most of the selected marker genes at the mRNA level. MpOx-LDLs also modulate marker gene expression in polarized macrophages favoring notably anti-inflammatory Arg1 expression in M2 cells and also in the other phenotypes. Noteworthy, MpOx-LDLs were the most efficient to accumulate lipids intracellularly in (un)polarized macrophages whatever the phenotype. These data were largely confirmed in murine bone marrow-derived macrophages. Our data suggest that MpOx-LDLs were the most efficient to accumulate within cells and to enhance an anti-inflammatory and antioxidant phenotype in M2 cells and also in the other macrophage phenotypes.