Plasma Myeloperoxidase Levels Research Articles

Myeloperoxidase induces monocyte migration and activation after acute myocardial infarction.

Myocardial infarction (MI) is a significant contributor to morbidity and mortality worldwide. Many individuals who survive the acute event continue to experience heart failure (HF), with inflammatory and healing processes post-MI playing a pivotal role. Polymorphonuclear neutrophils (PMN) and monocytes infiltrate the infarcted area, where PMN release high amounts of the heme enzyme myeloperoxidase (MPO). MPO has numerous inflammatory properties and MPO plasma levels are correlated with prognosis and severity of MI. While studies have focused on MPO inhibition and controlling PMN infiltration into the infarcted tissue, less is known on MPO's role in monocyte function. Here, we combined human data with mouse and cell studies to examine the role of MPO on monocyte activation and migration. We revealed a correlation between plasma MPO levels and monocyte activation in a patient study. Using a mouse model of MI, we demonstrated that MPO deficiency led to an increase in splenic monocytes and a decrease in cardiac monocytes compared to wildtype mice (WT). In vitro studies further showed that MPO induces monocyte migration, with upregulation of the chemokine receptor CCR2 and upregulation of inflammatory pathways identified as underlying mechanisms. Taken together, we identify MPO as a pro-inflammatory mediator of splenic monocyte recruitment and activation post-MI and provide mechanistic insight for novel therapeutic strategies after ischemic injury.

Endothelial PTP1B Deletion Promotes VWF Exocytosis and Venous Thromboinflammation.

Endothelial activation promotes the release of procoagulant extracellular vesicles and inflammatory mediators from specialized storage granules. Endothelial membrane exocytosis is controlled by phosphorylation. We hypothesized that the absence of PTP1B (protein tyrosine phosphatase 1B) in endothelial cells promotes venous thromboinflammation by triggering endothelial membrane fusion and exocytosis. Mice with inducible endothelial deletion of PTP1B (End.PTP1B-KO) underwent inferior vena cava ligation to induce stenosis and venous thrombosis. Primary endothelial cells from transgenic mice and human umbilical vein endothelial cells were used for mechanistic studies. Vascular ultrasound and histology showed significantly larger venous thrombi containing higher numbers of Ly6G (lymphocyte antigen 6 family member G)-positive neutrophils in mice with endothelial PTP1B deletion, and intravital microscopy confirmed the more pronounced neutrophil recruitment following inferior vena cava ligation. RT2 PCR profiler array and immunocytochemistry analysis revealed increased endothelial activation and adhesion molecule expression in primary End.PTP1B-KO endothelial cells, including CD62P (P-selectin) and VWF (von Willebrand factor). Pretreatment with the NF-κB (nuclear factor kappa B) kinase inhibitor BAY11-7082, antibodies neutralizing CD162 (P-selectin glycoprotein ligand-1) or VWF, or arginylglycylaspartic acid integrin-blocking peptides abolished the neutrophil adhesion to End.PTP1B-KO endothelial cells in vitro. Circulating levels of annexin V+ procoagulant endothelial CD62E+ (E-selectin) and neutrophil (Ly6G+) extracellular vesicles were also elevated in End.PTP1B-KO mice after inferior vena cava ligation. Higher plasma MPO (myeloperoxidase) and Cit-H3 (citrullinated histone-3) levels and neutrophil elastase activity indicated neutrophil activation and extracellular trap formation. Infusion of End.PTP1B-KO extracellular vesicles into C57BL/6J wild-type mice most prominently enhanced the recruitment of endogenous neutrophils, and this response was blunted in VWF-deficient mice or by VWF-blocking antibodies. Reduced PTP1B binding and tyrosine dephosphorylation of SNAP23 (synaptosome-associated protein 23) resulting in increased VWF exocytosis and neutrophil adhesion were identified as mechanisms, all of which could be restored by NF-κB kinase inhibition using BAY11-7082. Our findings show that endothelial PTP1B deletion promotes venous thromboinflammation by enhancing SNAP23 phosphorylation, endothelial VWF exocytosis, and neutrophil recruitment.

The Causal Relationship between Plasma Myeloperoxidase Levels and Respiratory Tract Infections: A Bidirectional Mendelian Randomization Study.

Observational researches reported the underlying correlation of plasma myeloperoxidase (MPO) concentration with respiratory tract infections (RTIs), but their causality remained unclear. Here, we examined the cause-effect relation between plasma MPO levels and RTIs. Datasets of plasma MPO levels were from the Folkersen et al. study (n = 21,758) and INTERVAL study (n = 3,301). Summarized data for upper respiratory tract infection (URTI) (2,795 cases and 483,689 controls) and lower respiratory tract infection (LRTI) in the intensive care unit (ICU) (585 cases and 430,780 controls) were from the UK Biobank database. The primary method for Mendelian randomization (MR) analysis was the inverse variance weighted approach, with MR-Egger and weighted median methods as supplements. Cochrane's Q test, MR-Egger intercept test, MR pleiotropy residual sum and outliers global test, funnel plots, and leave-one-out analysis were used for sensitivity analysis. We found that plasma MPO levels were positively associated with URTI (odds ratio (OR) = 1.135; 95% confidence interval (CI) = 1.011-1.274; P=0.032) and LRTI (ICU) (OR = 1.323; 95% CI = 1.006-1.739; P=0.045). The consistent impact direction is shown when additional plasma MPO level genome-wide association study datasets are used (URTI: OR = 1.158; 95% CI = 1.072-1.251; P < 0.001; LRTI (ICU): OR = 1.216; 95% CI = 1.020-1.450; P=0.030). There was no evidence of a causal effect of URTI and LRTI (ICU) on plasma MPO concentration in the reverse analysis (P > 0.050). The sensitivity analysis revealed no violations of MR presumptions. Plasma MPO levels may causally affect the risks of URTI and LRTI (ICU). In contrast, the causal role of URTI and LRTI (ICU) on plasma MPO concentration was not supported in our MR analysis. Further studies are needed to identify the relationship between RTIs and plasma MPO levels.

Macrophage-1 antigen exacerbates histone-induced acute lung injury and promotes neutrophil extracellular trap formation.

Acute lung injury (ALI), which occurs in association with sepsis, trauma, and coronavirus disease 2019 (COVID-19), is a serious clinical condition with high mortality. Excessive platelet-leukocyte aggregate (PLA) formation promotes neutrophil extracellular trap (NET) release and thrombosis, which are involved in various diseases, including ALI. Macrophage-1 antigen (Mac-1, CD11b/CD18), which is expressed on the surface of leukocytes, is known to promote NET formation. This study aimed to elucidate the role of Mac-1 in extracellular histone-induced ALI. Exogenous histones were administered to Mac-1-deficient mice and wild-type (WT) mice with or without neutrophil or platelet depletion, and several parameters were investigated 1 h after histone injection. Depletion of neutrophils or platelets improved survival time and macroscopic and microscopic properties of lung tissues, and decreased platelet-leukocyte formation and plasma myeloperoxidase levels. These improvements were also observed in Mac-1-/- mice. NET formation in Mac-1-/- bone marrow neutrophils (BMNs) was significantly lower than that in WT BMNs. In conclusion, our findings suggest that Mac-1 is associated with exacerbation of histone-induced ALI and the promotion of NET formation in the presence of activated platelets.

Mast cell-derived IL-10 protects intestinal barrier integrity during malaria in mice and regulates parasite transmission to Anopheles stephensi with a female-biased immune response.

Malaria is strongly predisposed to bacteremia, which is associated with increased gastrointestinal permeability and a poor clinical prognosis. We previously identified mast cells (MCs) as mediators of intestinal permeability in malaria and described multiple cytokines that rise with parasitemia, including interleukin (IL)-10, which could protect the host from an inflammatory response and alter parasite transmission to Anopheles mosquitoes. Here, we used the Cre-loxP system and non-lethal Plasmodium yoelii yoelii 17XNL to study the roles of MC-derived IL-10 in malaria immunity and transmission. Our data suggest a sex-biased and local inflammatory response mediated by MC-derived IL-10, supported by early increased number and activation of MCs in females relative to males. Increased parasitemia in female MC IL-10 (-) mice was associated with increased ileal levels of chemokines and plasma myeloperoxidase (MPO). We also observed increased intestinal permeability in female and male MC IL-10 (-) mice relative to MC IL-10 (+) mice but no differences in blood bacterial 16S DNA levels. Transmission success of P. yoelii to A. stephensi was higher in female relative to male mice and from female and male MC IL-10 (-) mice relative to MC IL-10 (+) mice. These patterns were associated with increased plasma levels of pro-inflammatory cytokines in female MC IL-10 (-) mice and increased plasma levels of chemokines and markers of neutrophil activation in male MC IL-10 (-) mice. Overall, these data suggest that MC-derived IL-10 protects intestinal barrier integrity, regulates parasite transmission, and controls local and systemic host immune responses during malaria, with a female bias.

EVALUATING THE PRE-CLINICAL EFFICACY OF VT1021 (A CLINICAL STAGE DRUG CANDIDATE) IN MULTIPLE EXPERIMENTAL MODELS OF INFLAMMATORY BOWEL DISEASE

Abstract Inflammatory bowel disease (IBD) is characterized symptomatically by chronic inflammation in the colonic tract. Despite the increased understanding of the physiological symptoms of Crohn’s Disease, and IBD in general, there have been no significant breakthroughs in understanding its etiology or improving treatment. As such, there is an urgent need for efficacious therapies that are aimed specifically at preventing or curing IBD. Bolstering the need for better therapies is the fact that patients with IBD have increased risk of developing intestinal cancers. One of the pathological traits of IBD that heightens the risk of cancer is the increased level of angiogenesis that accompanies the inflammation. As the biological processes of angiogenesis and inflammation are intricately linked, we believe increasing the levels of thrombospondin-1 (TSP-1), an anti-angiogenic and anti-inflammatory protein, can reprogram immune and inflammatory cells to inhibit angiogenesis and induce the resolution of inflammation. Vigeo has developed VT1021 which stimulates the expression of TSP-1 in inflammatory myeloid derived suppressor cells (MDSCs) systemically. VT1021 achieved proof of concept in a Phase 1/2 clinical trial with multiple cohorts and is currently in Phase 2/3 trials for oncology indications. IBD patients have increased MDSCs in both lesions and peripheral blood. MDSCs are genomically stable and not mutated in IBD patients and thus represent ideal therapeutic targets. Two dextran sulfate sodium (DSS)-induced colitis models were used to evaluate the pre-clinical efficacy of VT1021. In the preventative model, mice were treated with 4% DSS from Day 0 to Day 6 and either saline or VT1021 from Day 0 to Day 8, then sacrificed on Day 8 to collect colon tissue and plasma samples. In the rescue model, mice were treated with 4% DSS from Day 0 to Day 4, then treated with either saline, VT1021 (25, 50, 100 mg/kg) or anti-TNFa from Day 5 to Day 10. Mice were sacrificed on Day 11; colon tissue and plasma samples were collected. In both models, VT1021 treatment significantly prevented the mouse weight loss and bloody stool compared to the saline treatment. VT1021 treatment also decreased the colon inflammation by the measurement of both plasma myeloperoxidase (MPO) level and colon tissue histopathology score. Immunohistochemistry staining of colon tissue samples confirmed that VT1021 treatment stimulated TSP-1 expression in the MDSCs. Altogether, these findings show that VT1021 treatment has equivalent efficacy to anti-TNFa treatment, while significantly reducing damage to colon tissue. We believe VT1021 will show significantly greater efficacy in patients with longer term use, while avoiding the systemic deleterious side effects common to current approved therapies.

Diagnostic Utility of a Combined MPO/D-Dimer Score to Distinguish Abdominal Aortic Aneurysm from Peripheral Artery Disease.

Abdominal aortic aneurysm (AAA) and peripheral artery disease (PAD) share pathophysiological mechanisms including the activation of the fibrinolytic and innate immune system, which explains the analysis of D-dimer and myeloperoxidase (MPO) in both conditions. This study evaluates the diagnostic marker potential of both variables separately and as a combined MPO/D-dimer score for identifying patients with AAA versus healthy individuals or patients with PAD. Plasma levels of MPO and D-dimer were increased in PAD and AAA compared to healthy controls (median for MPO: 13.63 ng/mL [AAA] vs. 11.74 ng/mL [PAD] vs. 9.16 ng/mL [healthy], D-dimer: 1.27 μg/mL [AAA] vs. 0.58 μg/mL [PAD] vs. 0.38 μg/mL [healthy]). The combined MPO/D-dimer score (median 1.26 [AAA] vs. -0.19 [PAD] vs. -0.93 [healthy]) showed an improved performance in distinguishing AAA from PAD when analysed using the receiver operating characteristic curve (area under the curve) for AAA against the pooled data of healthy controls + PAD: 0.728 [MPO], 0.749 [D-dimer], 0.801 [score]. Diagnostic sensitivity and specificity ranged at 82.9% and 70.2% (for score cut-off = 0). These findings were confirmed for a separate collective of AAA patients with 35% simultaneous PAD. Thus, evaluating MPO together with D-dimer in a simple score may be useful for diagnostic detection and the distinction of AAA from athero-occlusive diseases like PAD.

Interactions between Integrin α9β1 and VCAM-1 Promote Neutrophil Hyperactivation and Deep Vein Thrombosis in a Murine Model of Lung Cancer

Background: Venous thromboembolism (VTE) is highly prevalent in patients with lung cancer and is associated with increased morbidity and mortality. Ectopic secretion of granulocyte colony-stimulating factor (G-CSF), a critical regulator of neutrophil trafficking, is commonly observed in lung cancer. In recent years, compelling evidence has emerged implicating neutrophils and neutrophil extracellular traps (NETosis) in cancer-associated thrombosis. Integrin α9β1 is highly expressed on neutrophils, upregulated upon neutrophil activation, promotes NETosis, and is known to stabilize neutrophil adhesion to activated endothelium via multiple ligands including vascular cell adhesion molecule 1 (VCAM-1). Interactions between integrin α9 and VCAM-1 have been reported to reduce neutrophils apoptosis. Given the relevance of integrin α9 in neutrophil migration and apoptosis, granulopoiesis, and thromboinflammation, here we evaluated the mechanistic role of neutrophil integrin α9β1 in the pathophysiology of cancer-associated thrombosis. Methods: Lung cancer was induced by the intravenous administration of 3X10 5 Lewis lung carcinoma cells. Deep vein thrombosis (DVT) was induced in neutrophil-specific α9 -/- (α9 fl/flMrp8Cre +/-) and littermate controls (α9 fl/flMrp8Cre -/-) by partial ligation of the inferior vena cava (IVC). Plasma levels of the thrombin-antithrombin (TAT) complex, fibrinogen, G-CSF, elastase, and myeloperoxidase (MPO) were assessed by ELISA. To evaluate the potential mechanisms by which neutrophil integrin α9-VCAM-1 interactions promote DVT, we performed unbiased RNA sequencing from 1) control neutrophils stimulated with and without VCAM-1 and, 2) neutrophils of α9 fl/flMrp8Cre +/- and α9 fl/flMrp8Cre -/- mice stimulated with VCAM-1. Computational modeling, docking, virtual screening, and the cell-free assay were used to identify small-molecule inhibitors of integrin α9-VCAM-1 interaction. Results: Mice with lung cancer exhibited significantly increased levels of TAT, G-CSF, blood neutrophil/lymphocyte ratio, cell-free DNA, elastase, and MPO, suggesting a hypercoagulable and inflammatory state. Tumor-bearing and non-tumor-bearing neutrophil-specific α9 -/- mice exhibited reduced DVT severity, as evident by reduced IVC thrombus weight and thrombus length compared to littermate controls, while thrombosis incidence was comparable between the groups. Reduced DVT severity in neutrophil-specific α9 -/- mice was also associated with decreased neutrophil content and citrullinated histone H3 (CitH3) expression in IVC thrombi. Integrin α9 deficient neutrophils incubated with VCAM-1 exhibited reduced release of elastase and MPO, decreased endothelial cell apoptosis, and reduced adhesion to the activated endothelium at venous shear rate compared to control neutrophils incubated with VCAM-1. Bioinformatic analysis of RNA sequencing data from VCAM-1 stimulated neutrophils from α9 fl/flMrp8Cre +/- and control mice showed distinct transcriptional profiles. Hierarchical clustering of gene expression revealed gene clusters that were highly downregulated in stimulated neutrophils from α9 fl/flMrp8Cre +/- mice. Gene ontology enrichment revealed that highly downregulated genes corresponded to biological processes involved in the inflammatory response, cytokine production, NF-κB and ERK signaling pathways, granulocyte migration, and chemotaxis. Virtual screening and cell-free assay identified macitentan as a potent inhibitor of integrin α9-VCAM-1 interactions. In vitro treatment with macitentan reduced neutrophil adhesion to VCAM-1 and also to activated endothelial cells at venous shear rate. In vivo, macitentan treatment at a dose of 5 mg/kg exhibited reduced DVT severity, decreased plasma levels of elastase and MPO, and reduced neutrophil and CitH3 levels in IVC thrombi. Conclusion: Using genetic and pharmacological approaches in combination with transcriptomic and pharmacological studies, we described a previously unknown pathway involving integrin α9 and VCAM-1 in promoting cancer-associated thrombosis. We found that integrin α9-VCAM1 axis is critical for neutrophil hyperactivation, and its pharmacological inhibition significantly reduces DVT severity. The results of this study suggest that neutrophil integrin α9 is a key factor regulating neutrophil hyperactivation and cancer-associated thrombosis.

Plasma myeloperoxidase: association with atrial fibrillation progression and recurrence after catheter ablation.

Myeloperoxidase (MPO), released by activated neutrophils, is significantly increased in atrial fibrillation (AF). MPO may play a role in the progression of atrial fibrillation and further involved in AF recurrence after catheter ablation. We compared plasma MPO levels in paroxysmal and persistent AF and explored their role in AF recurrence after catheter ablation. Plasma MPO levels were measured in consecutive patients with paroxysmal AF (n = 225) and persistent AF (n = 106). Samples of patients were collected from the femoral vein during catheter ablation and all patients included were followed up after catheter ablation. Plasma MPO levels increased from paroxysmal AF to persistent AF patients (56.31 [40.33-73.51] vs. 64.11 [48.65-81.11] ng/ml, p < 0.001). MPO significantly correlated with left atrium volume (LAV) and there existed a significant interaction between the two in relation to AF recurrence (p for interaction <0.05). During a median follow-up of 14 months, 28 patients with paroxysmal AF (12.44%) and 27 patients with persistent AF (25.47%) presented with recurrence after catheter ablation. The percentage of recurrence increased stepwise with increasing tertiles of MPO levels in both paroxysmal AF and persistent AF. MPO levels remained independently associated with AF recurrence after adjusting for potential confounding variables. MPO levels were higher in persistent AF than in paroxysmal AF and MPO was positively correlated with LAV in AF. Elevated MPO levels may predispose a switch in AF phenotype and AF recurrence after catheter ablation.

The role and mechanism of myeloperoxidase in dermatomyositis

ObjectiveDermatomyositis (DM) is the best known subtype of idiopathic inflammatory myopathies. The hallmarks of DM muscle pathology including microangiopathy, inflammatory infiltration, and perifascicular atrophy. Recent findings have revealed pathogenetic effects of myeloperoxidase (MPO) by causing oxidative damage and regulating abnormal immunity in multiple disease conditions. In this study, we aimed to explore the role of MPO in the pathogenesis of DM. MethodsThe peripheral blood mononuclear cell (PBMC) mRNA expression and DNA methylation of MPO were verified using real-time qPCR and bisulfite pyrosequencing, respectively. Plasma MPO levels were measured with enzyme-linked immunosorbent assay, and their relationships with clinical characteristics were analyzed. The expression and distribution of MPO in muscle were tested by immunofluorescence. Purified human native MPO protein was used to stimulate human dermal microvascular endothelial cells (HDMECs) and skeletal muscle myotubes. The cell viability, tube forming capacity, permeability, adhesion molecule expressions in HDMECs, and atrophy and programmed cell death pathways in myotubes were then observed. ResultsMPO gene methylation was decreased, while mRNA expression and plasma levels were increased in DM. Plasma MPO of DM patients was positively correlated with serum creatine kinase (CK). MPO mainly distributed around endomysia capillaries and perifascicular atrophy in DM muscle biopsies, and was co-localized with CD4+, CD8+ T cells and CD19+ B cells. MPO not only could influence the cell viability, tube forming capacity, permeability and expression of adhesion molecules (including ICAM 1, VCAM 1 and E-selectin) of HDMECs, but also could cause atrophy of myotubes. ConclusionsOur study disclosed, for the first time, that MPO plays an important role in promoting inflammatory infiltration and inducing muscle damage in DM patients. MPO may be a potential biomarker for DM muscle involvement and MPO targeted drugs may be promising in DM treatment.

Regulation of coagulation activation in newly diagnosed AML by the heme enzyme myeloperoxidase

IntroductionPatients with acute myeloid leukemia (AML) are at increased risk of thrombohemorrhagic complications. Overexpressed tissue factor (TF) on AML blasts contributes to systemic coagulation activation. We have recently shown that the heme enzyme myeloperoxidase (MPO) negatively regulates TF procoagulant activity (PCA) on myelomonocytic cells in vitro. We now aimed to further characterize the functional interaction of MPO and TF in AML in vivo. MethodsWe prospectively recruited 66 patients with newly diagnosed AML. TF PCA of isolated peripheral blood mononuclear cells (PBMC) was assessed by single-stage clotting assay in the presence or absence of inhibitors against MPO catalytic activity (ABAH) or against MPO-binding integrins (anti-CD18). MPO in plasma and in AML blasts was measured by ELISA, and plasma D-dimers and prothrombin fragment F1+2 were quantified by automated immunoturbidimetric and chemiluminescence assays, respectively. ResultsPatients with AML had significantly higher MPO plasma levels compared to healthy controls and exhibited increased levels of D-dimers and F1+2. In vivo thrombin generation was mediated by TF PCA on circulating PBMC. Ex vivo incubation of isolated PBMC with ABAH or anti-CD18 antibody resulted in either increased or decreased TF PCA. The strong and robust correlation of F1+2 with TF PCA of circulating PBMC was abrogated at MPO plasma levels higher than 150 ng/mL, indicating a modulatory role for MPO on TF-mediated in vivo thrombin generation above this threshold. ConclusionOur study indicates that catalytically active MPO released by circulating myeloblasts regulates TF-dependent coagulation in patients with newly diagnosed AML in a CD18-dependent manner.

Tocotrienol-Rich Fraction Ameliorates the Aluminium Chloride-Induced Neurovascular Dysfunction-Associated Vascular Dementia in Rats.

Neurovascular dysfunction leads to the second most common type of dementia, i.e., vascular dementia (VaD). Toxic metals, such as aluminium, increase the risk of neurovascular dysfunction-associated VaD. Hence, we hypothesized that a natural antioxidant derived from palm oil, i.e., tocotrienol-rich fraction (TRF), can attenuate the aluminium chloride (AlCl3)-induced VaD in rats. Rats were induced with AlCl3 (150 mg/kg) intraperitoneally for seven days followed by TRF treatment for twenty-one days. The elevated plus maze test was performed for memory assessment. Serum nitrite and plasma myeloperoxidase (MPO) levels were measured as biomarkers for endothelial dysfunction and small vessel disease determination. Thiobarbituric acid reactive substance (TBARS) was determined as brain oxidative stress marker. Platelet-derived growth factor-C (PDGF-C) expression in the hippocampus was identified using immunohistochemistry for detecting the neovascularisation process. AlCl3 showed a significant decrease in memory and serum nitrite levels, while MPO and TBARS levels were increased; moreover, PDGF-C was not expressed in the hippocampus. However, TRF treatment significantly improved memory, increased serum nitrite, decreased MPO and TBARS, and expressed PDGF-C in hippocampus. Thus, the results imply that TRF reduces brain oxidative stress, improves endothelial function, facilitates hippocampus PDGF-C expression for neovascularisation process, protects neurons, and improves memory in neurovascular dysfunction-associated VaD rats.

Effect of remote ischemic conditioning on the immune-inflammatory profile in patients with traumatic hemorrhagic shock in a randomized controlled trial

Resuscitation induced ischemia/reperfusion predisposes trauma patients to systemic inflammation and organ dysfunction. We investigated the effect of remote ischemic conditioning (RIC), a treatment shown to prevent ischemia/reperfusion injury in experimental models of hemorrhagic shock/resuscitation, on the systemic immune-inflammatory profile in trauma patients in a randomized trial. We conducted a prospective, single-centre, double-blind, randomized, controlled trial involving trauma patients sustaining blunt or penetrating trauma in hemorrhagic shock admitted to a Level 1 trauma centre. Patients were randomized to receive RIC (four cycles of 5-min pressure cuff inflation at 250 mmHg and deflation on the thigh) or a Sham intervention. The primary outcomes were neutrophil oxidative burst activity, cellular adhesion molecule expression, and plasma levels of myeloperoxidase, cytokines and chemokines in peripheral blood samples, drawn at admission (pre-intervention), 1 h, 3 h, and 24 h post-admission. Secondary outcomes included ventilator, ICU and hospital free days, incidence of nosocomial infections, 24 h and 28 day mortality. 50 eligible patients were randomized; of which 21 in the Sham group and 18 in the RIC group were included in the full analysis. No treatment effect was observed between Sham and RIC groups for neutrophil oxidative burst activity, adhesion molecule expression, and plasma levels of myeloperoxidase and cytokines. RIC prevented significant increases in Th2 chemokines TARC/CCL17 (P < 0.01) and MDC/CCL22 (P < 0.05) at 24 h post-intervention in comparison to the Sham group. Secondary clinical outcomes were not different between groups. No adverse events in relation to the RIC intervention were observed. Administration of RIC was safe and did not adversely affect clinical outcomes. While trauma itself modified several immunoregulatory markers, RIC failed to alter expression of the majority of markers. However, RIC may influence Th2 chemokine expression in the post resuscitation period. Further investigation into the immunomodulatory effects of RIC in traumatic injuries and their impact on clinical outcomes is warranted.ClinicalTrials.gov number: NCT02071290.

Orally administered MOTS-c analogue ameliorates dextran sulfate sodium-induced colitis by inhibiting inflammation and apoptosis

Inflammatory bowel disease (IBD) is a chronic and relapsing inflammatory disorder of the gastrointestinal tract (GI). Currently, the treatment options for IBD are limited. It has been reported that a novel bioactive mitochondrial-derived peptide (MOTS-c) encoded in the mitochondrial 12S rRNA, suppresses inflammatory response by enhancing the phagocytosis of macrophages. The aim of this study was to investigate the protective effects of MOTS-c against dextran sulfate sodium (DSS)-induced colitis. The results showed that intraperitoneal (i.p.) administration of MOTS-c significantly ameliorated the symptoms of DSS-induced experimental colitis, such as body weight loss, colon length shortening, diarrhea, and histological damage. MOTS-c down-regulated the expression of pro-inflammatory cytokines, decreased the plasma levels of myeloperoxidase, and inhibited the activation of macrophages and recruitment of neutrophils. Moreover, treatment with MOTS-c exhibited anti-apoptotic effects and significantly suppressed the phosphorylation of AMPKα1/2, ERK, and JNK. Notably, oral administration of MOTS-c did not result in any significant improvements. Screening of cell penetrating peptides was performed, (PRR)5 was linked to the C-terminus of MOTS-c through a linker to synthesize a new molecule (termed MP) with better penetration into the colon epithelium. In vitro experiments revealed the longer half-life of MP than MOTS-c, and in vivo experiments showed that oral administration of MP significantly ameliorated DSS-induced colitis. ConclusionThe present results demonstrate a protective role of MOTS-c in experimental IBD.

Effects of Low-Dose Colchicine on Serum High-Sensitivity C-Reactive Protein Level in Coronary Artery Disease Patients with Type 2 Diabetes Mellitus and Enhanced Inflammatory Response Protocol for a Randomized, Double-Blind, Placebo-Controlled, Phase 2, Dose-Finding Study

Although cardiovascular mortality in Japan is lower than in other industrialized countries, clinical outcomes in coronary artery disease (CAD) patients with type 2 diabetes mellitus (T2DM) remain poor despite multiple evidence-based drug therapies and interventions. We assumed that part of residual risk in these patients may be attributable to enhanced inflammation, which can be inhibited presumably by colchicine. However, dose-responsiveness of anti-inflammatory effect of colchicine has not been elucidated. Therefore, we designed a multicenter, randomized, double-blinded, parallel-group study to explore the dose-dependent effects of low-dose colchicine on serum high-sensitivity C-reactive protein (hs-CRP) concentration and safety in CAD patients with T2DM and enhanced inflammatory response as a phase 2 study. Enhanced inflammatory response was defined as peripheral white-blood cell count ≥7,000/μL. Patients (N = 63) will be randomly assigned to two doses of colchicine 0.25 mg/day, 0.5 mg/day, or placebo in a 1:1:1 ratio once daily for 12 weeks. Changes in serum hs-CRP levels will be evaluated as the primary endpoint, and changes in flow-mediated vasodilation and plasma myeloperoxidase levels will be evaluated as secondary endpoints. The results of this study will contribute to the development of a protocol for a planned future phase 3 trial to estimate the reduction in CAD. The present study describes the rationale, design, and methods of the trial.

Association between myeloperoxidase and the risks of ischemic stroke, heart failure, and atrial fibrillation: A Mendelian randomization study

Background and aimsThe causality between myeloperoxidase (MPO) and cardiovascular disease still remains unclear. We performed a two-sample Mendelian randomization (MR) study to estimate the potential causal effect of MPO on the risks of ischemic stroke, ischemic stroke subtypes, heart failure (HF), and atrial fibrillation (AF). Methods and resultsSeventeen independent single-nucleotide polymorphisms associated with MPO levels were identified as instrumental variables from a European-descent genome-wide association study. Summary-level data on ischemic stroke originated from the Multiancestry Genome-wide Association Study of Stroke Consortium with 440 328 European individuals. We used the inverse-variance weighted method to assess the potential causality of plasma MPO with ischemic stroke and its subtypes in the main analysis. Genetically determined higher plasma MPO concentration was significantly associated with increased risks of ischemic stroke (odds ratio [OR] per standard deviation [SD] increase, 1.05; 95% confidence interval [CI], 1.02–1.09; P = 0.002) and cardioembolic stroke (CES) (OR per SD increase, 1.10; 95% CI, 1.03–1.18; P = 0.005), but was not associated with risks of large artery stroke or small vessel stroke. In the secondary analysis, MPO was associated with a high risk of HF (OR per SD increase, 1.05; 95% CI, 1.02–1.07; P = 0.001) and AF (OR per SD increase, 1.04; 95% CI, 1.01–1.07; P = 0.004). MR-Egger regression showed no directional pleiotropy for all associations, and the sensitivity analyses further confirmed these findings. ConclusionHigh plasma MPO levels were potentially associated with increased risks of ischemic stroke, CES, HF, and AF, suggesting that MPO plays an important role in the development of cardiovascular disease.

Plasma Myeloperoxidase as a Potential Biomarker of Patient Response to Anti-Dementia Treatment in Alzheimer's Disease.

Myeloperoxidase (MPO), a neutrophil-derived pro-inflammatory protein, co-localizes with amyloid-β (Aβ) plaques in Alzheimer's disease (AD). Anti-dementia treatment may facilitate efflux of Aβ and associated plaque proteins from the brain to the peripheral circulation, therefore providing potential biomarkers for the monitoring of donor response to drug treatment. We investigated the diagnostic utility of MPO as a biomarker of AD, and how anti-dementia treatment alters plasma MPO concentration. Thirty-two AD patients were recruited, and plasma collected pre-drug administration (baseline), and 1- and 6-months post-treatment. All patients received cholinesterase inhibitors (ChEIs). At baseline and 6 months, patients underwent neuropsychological assessment. Forty-nine elderly healthy individuals with normal cognitive status served as controls. Plasma MPO concentration was measured by ELISA. AD drug naïve patients had similar plasma MPO concentration to their control counterparts (p &gt; 0.05). Baseline MPO levels positively correlated with Neuropsychiatric Inventory score (r = 0.5080; p = 0.011) and carer distress (r = 0.5022; p = 0.012). Following 1-month ChEI treatment, 84.4% of AD patients exhibited increased plasma MPO levels (p &lt; 0.001), which decreased at 6 months (p &lt; 0.001). MPO concentration at 1 month was greatest in AD patients whose memory deteriorated during the study period (p = 0.028), and for AD patients with deterioration in Cornell assessment score (p = 0.044). Whereas baseline MPO levels did not differentiate between healthy and AD populations, baseline MPO positively correlated with initial Neuropsychiatric Inventory evaluation. Post-treatment, transient MPO upregulation in ChEI-treated patients may reflect worse therapeutic outcome. Further studies are required to assess the potential of plasma MPO as an AD therapeutic biomarker.

Could myeloperoxidase be a biomarker or predictor for colorectal cancer?

Aim: Colorectal cancer (CRC) is the 4th most common cancer, and tumor tissue has a higher amount of myeloperoxidase (MPO)-positive cells than normal tissue. We aimed to compare the parameters of myeloid and lymphoid cells and MPO levels in the venous blood of patients diagnosed with CRC and healthy volunteers. Materials and methods: The patient group in the study consisted of people who were diagnosed with CRC and had not yet received local or systemic treatment. The control group was selected from non-cancer patients. The enzyme-linked immunosorbent assay was used for the quantitative determination of MPO in serum. Results: A total of 56 patients were included in this study. The mean MPO level of the patient group was significantly lower than that of the control group (3.59, 5.2 pg/mL, p=0.007). As a result of the receiver operating characteristics curve analysis, the cut-off point obtained for MPO was determined to be 3.66. There were significantly more CRC patients in the group with an MPO value of 3.66 and below (p=0.001; p&lt;0.01). An MPO value of 3.66 or below increased the risk of CRC by 8.13 times. Conclusions: In our study, the serum MPO level was significantly lower in the CRC patients, suggesting that immune system cells in CRC tend to behave differently in cancerous tissue and the general circulatory system. In the light of future studies on this subject, simple and easily reproducible determination of plasma MPO level may help to predict the prognosis, treatment planning, response to treatment, and efficacy of immunotherapy in CRC. Keywords: Colorectal cancer, myeloperoxidase, predictor

Myeloperoxidase as prognostic factor for atrial fibrillation development in patients with ST-segment elevation myocardial infarction

Abstract Funding Acknowledgements Type of funding sources: None. Background Arrhythmia is among the most common and severe myocardial infarction complications. Myeloperoxidase as an important immune factor can be linked to atrial fibrillation (AF) development. Previous studies indicated myeloperoxidase (MPO) as a significant mortality predictor in ST-segment elevation myocardial infarction (STEMI). The MPO role in prognosis for adverse clinical outcomes, as atrial fibrillations in STEMI patients remains not fully understood. The purpose of the investigation was to examine the MPO in prognosis of adverse outcomes presented by atrial fibrillations in patients with STEMI. Methods The study included 233 STEMI patients, 112 males, 121 females, and average age 67.87±7.11 years. Follow-up period was 14 days. Adverse outcome was observed and included atrial fibrillations. Plasma MPO levels were determined by ELISA, MPO was collected on admission. Results Patients with indicated adverse effects showed significantly increased MPO levels compared to those without ones, 169.91 IQR [89.45; 201.98] ng/ml vs 81.4 [33.91;181.29] ng/ml; p &amp;lt; 0.001. A ROC analysis determined a MPO cut-off value for arrhythmia (AF) development of 176.53 ng/ml with a sensitivity of 71.1% and specificity of 77.6%, AUC 0.732; 95 % CI 0.677-0.782; p &amp;lt;0.001. Elevated MPO concentration was a significant predictor for AF (OR 1.115; 95% CI: 1.007-1.841; p&amp;lt;0.001). Even adjusted for age and sex MPO remained significantly predictive for arrhythmia development. Conclusions The study suggests that increased levels of MPO are associated with the higher risk of atrial fibrillation. MPO could be a possible significant factor for therapy optimization in high-risk STEMI patients.

Experimental and validation of significance and accuracy of oxidized low-density lipoproteins and myeloperoxidase in the screening of cardio-vascular disease

The aim. To access the superiority of myeloperoxidase &amp; oxidized low-density lipoproteins over each other acts as a better predictive marker gaining information regarding the severity of cardiovascular disease.&#x0D; Materials and methods. 215 subjects are taken into consideration of which 54 are healthy controls, 52 are from stable angina pectoris, 53 are taken from unstable angina pectoris and 56 subjects are from acute myocardial infarction. Lipid profile parameters, oxidative stress markers, plasma myeloperoxidase and plasma oxidized low density lipoproteins were estimated by kit methods, thiobarbituric acid reactive substances method, and colorimetric assay, sandwich and competitive enzyme linked immunosorbent assay techniques, respectively. Results were present as mean ± SD, p-values &lt;0.05 as significant, and Student’s unpaired “t” test. Comparative analysis by box and whiskers plot to check skewness and deviations within the values. Data analysis was performed by software package SPSS version 17.0.&#x0D; Results. The oxidized low density lipoproteins levels found significantly elevated in all three cases subgroup contrary to insignificant levels of myeloperoxidase in stable angina pectoris compared to control. Box and whisker plot of myeloperoxidase levels showed no skewness in stable angina pectoris (non-significant), whereas unstable angina pectoris and acute myocardial infarction showed right skewness (highly significant), whereas plots of oxidized low-density lipoproteins show extensive interquartile range in the stable angina pectoris subgroup, suggesting scattered deviation in the mean values compared to unstable angina pectoris and acute myocardial infarction subgroup.&#x0D; Conclusions. The study concluded that significantly elevated level of oxidized low-density lipoproteins in stable angina pectoris, unstable angina pectoris, and acute myocardial infarction subgroups with a scattered deviation of oxidized low density lipoproteins levels in the stable angina pectoris subgroup reflects its low prognostic reliability compared to plasma myeloperoxidase with marginal deviation and in insignificant elevation in stable angina pectoris. Thus, plasma myeloperoxidase and oxidized low density lipoproteins levels serve as independent predictors of cardiovascular disease, but plasma myeloperoxidase levels predict an increased risk over oxidized low density lipoproteins for subsequent cardiovascular events in stable and unstable angina and extend the prognostic information gained from traditional biochemical markers