Low-Density Neutrophils Contribute to Subclinical Inflammation in Patients with Type 2 Diabetes.

Type 2 diabetes (T2D) is characterized by low-grade inflammation. Low-density neutrophils (LDNs) represent normally less than 2% of total neutrophils but increase in multiple pathologies, releasing inflammatory cytokines and neutrophil extracellular traps (NETs). We assessed the count and role of high-density neutrophils (HDNs), LDNs, and NET-related activities in patients with T2D. HDNs and LDNs were purified by fluorescence-activated cell sorting (FACS) and counted by flow cytometry. Circulating inflammatory and NETs biomarkers were measured by ELISA (Enzyme Linked Immunosorbent Assay). NET formation was quantified by confocal microscopy. Neutrophil adhesion onto a human extracellular matrix (hECM) was assessed by optical microscopy. We recruited 22 healthy volunteers (HVs) and 18 patients with T2D. LDN counts in patients with diabetes were significantly higher (160%), along with circulating NETs biomarkers (citrullinated H3 histone (H3Cit), myeloperoxidase (MPO), and MPO-DNA (137%, 175%, and 69%, respectively) versus HV. Circulating interleukins (IL-6 and IL-8) and C-Reactive Protein (CRP) were significantly increased by 117%, 171%, and 79%, respectively, in patients compared to HVs. Isolated LDNs from patients expressed more H3Cit, MPO, and NETs, formed more NETs, and adhered more on hECM compared to LDNs from HVs. Patients with T2D present higher levels of circulating LDN- and NET-related biomarkers and associated pro-inflammatory activities.

Angiopoietin 1 release from human neutrophils is independent from neutrophil extracellular traps (NETs).

BACKGROUND: Neutrophils induce the synthesis and release of angiopoietin 1 (Ang1), a cytosolic growth factor involved in angiogenesis and capable of inducing several pro-inflammatory activities in neutrophils. Neutrophils also synthesize and release neutrophil extracellular traps (NETs), comprised from decondensed nuclear DNA filaments carrying proteins such as neutrophil elastase (NE), myeloperoxidase (MPO), proteinase 3 (PR3) and calprotectin (S100A8/S100A9), which together, contribute to the innate immune response against pathogens (e.g., bacteria). NETs are involved in various pathological conditions through pro-inflammatory, pro-thrombotic and endothelial dysfunction effects and have recently been found in heart failure (HF) and type 2 diabetes (T2DM) patients. The aim of the present study was to investigate the role of NETs on the synthesis and release of Ang1 by the neutrophils in patients with T2DM and HF with preserved ejection fraction (HFpEF) (stable or acute decompensated; ADHFpEF) with or without T2DM. RESULTS: Our data show that at basal level (PBS) and upon treatment with LPS, levels of NETs are slightly increased in patients suffering from T2DM, HFpEF ± T2DM and ADHF without (w/o) T2DM, whereas this increase was significant in ADHFpEF + T2DM patients compared to healthy control (HC) volunteers and ADHFpEF w/o T2DM. We also observed that treatments with PMA or A23187 increase the synthesis of Ang1 (from 150 to 250%) in HC and this effect is amplified in T2DM and in all cohorts of HF patients. Ang1 is completely released (100%) by neutrophils of all groups and does not bind to NETs as opposed to calprotectin. CONCLUSIONS: Our study suggests that severely ill patients with HFpEF and diabetes synthesize and release a greater abundance of NETs while Ang1 exocytosis is independent of NETs synthesis.

Synthesis of Human Neutrophil Extracellular Traps Contributes to Angiopoietin-Mediated In Vitro Proinflammatory and Proangiogenic Activities.

Neutrophil extracellular traps (NETs) are composed of nuclear DNA in a web-like structure extruded from neutrophils in response to either bacterial infection or inflammation. We previously reported the expression of angiopoietin Tie2 receptor on human neutrophils and the capacity of both angiopoietins (Ang1 and Ang2) to induce proinflammatory activities, such as synthesis and release of platelet-activating factor, upregulation of ß2 integrin complex (CD11/CD18), and neutrophil chemotaxis. In contrast, only Ang1 but not Ang2 is capable of promoting translational and transcriptional activities in neutrophils. In this article, we addressed whether Ang1 and/or Ang2 could modulate the release of NETs and if they contribute to angiopoietin-mediated proinflammatory activities. We observed that Ang1 and Ang2, alone or combined (10 nM, 3 h), increase NET synthesis and release by ≈2.5-fold as compared with PBS-treated neutrophils. The release of NETs is Tie2 dependent and requires downstream intracellular participation of PI3K, p38, and p42/44 MAPK pathways; reactive oxygen species production; intracellular calcium store depletion; and protein arginine deiminase 4 activation. These isolated NETs induced neutrophil and endothelial cell activation, leading to neutrophil adhesion onto human extracellular matrix and HUVEC and in vitro formation of capillary-like tubes by endothelial cells. Our study reports the capacity of Ang1 and Ang2 to promote the release of NETs and that these NETs contribute to angiopoietin-mediated in vitro proinflammatory and proangiogenic activities.

A comparison of the effects of selective and non-selective mineralocorticoid antagonism on glucose homeostasis of heart failure patients with glucose intolerance or type II diabetes: A randomized controlled double-blind trial.

Mineralocorticoid receptor antagonists (MRAs) decrease morbidity and mortality in patients with heart failure (HF). However, spironolactone, a non-selective MRA, has been shown to exert a harmful effect on glucose homeostasis. The objective of this multicenter, randomized, controlled, double-blind trial was to compare the effects of spironolactone to those of the selective MRA eplerenone on glucose homeostasis among 62 HF patients with glucose intolerance or type II diabetes. Trial registration number:NCT01586442.

Low-Density Neutrophils and Neutrophil Extracellular Traps (NETs) Are New Inflammatory Players in Heart Failure.

BACKGROUND: Heart failure with reduced (HFrEF) or preserved ejection fraction (HFpEF) is characterized by low-grade chronic inflammation. Circulating neutrophils regroup 2 subtypes termed high- and low-density neutrophils (HDNs and LDNs). LDNs represent less than 2% of total neutrophil under physiological conditions, but their counts increase in multiple pathologies, releasing more inflammatory cytokines and neutrophil extracellular traps (NETs). The aims of this study were to assess the differential count and role of HDNs, LDNs, and NETs-related activities in patients with heart failure (HF). METHODS: HDNs and LDNs were isolated from human blood by density gradient and purified by fluorescence-activated cell sorting (FACS) and their counts obtained by flow cytometry. Formation of NETs (NETosis) was quantified by confocal microscopy. Circulating inflammatory and NETosis biomarkers were measured by enzyme-linked immunosorbent assay (ELISA). Neutrophil adhesion onto human extracellular matrix (hECM) was assessed by optical microscopy. RESULTS: A total of 140 individuals were enrolled, including 33 healthy volunteers (HVs), 41 HFrEF (19 stable patients and 22 presenting acute decompensated HF [ADHF]), and 66 patients with HFpEF (36 stable patients and 30 presenting HF decompensation). HDNs and LDNs counts were significantly increased up to 39% and 2740%, respectively, in patients with HF compared with HVs. In patients with HF, the correlations among LDNs counts and circulating inflammatory (CRP, IL-6 and -8), troponin T, N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and NETosis components were significant. In vitro, LDNs expressed more citrullinated histone H3 (H3Cit) and NETs and were more proadhesive, with ADHFpEF patients presenting the highest proinflammatory profile. CONCLUSIONS: Patients with HFpEF present higher levels of circulating LDNs- and NETs-related activities, which are the highest in the context of acute HF decompensation.

Angiopoietin-1 but not angiopoietin-2 promotes neutrophil viability: Role of interleukin-8 and platelet-activating factor.

We previously reported the expression of angiopoietin receptor Tie2 on human neutrophils. Both angiopoietins (Ang1 and Ang2) induce platelet activating factor (PAF) synthesis from endothelial cells (ECs) and neutrophils. Both angiopoietins can also modulate EC viability and since PAF can promote pro-survival activity on neutrophils, we addressed whether Ang1 and/or Ang2 could modulate neutrophil viability. Neutrophils were isolated from venous blood of healthy volunteers and neutrophil viability was assessed by flow cytometry using apoptotic and necrotic markers (annexin-V and propidium iodide (P.I.), respectively). Basal neutrophil viability from 0 to 24 h post-isolation decreased from 98% to ≈45%. Treatment with anti-apoptotic mediators such as interleukin-8 (IL-8; 25 nM) and PAF (100 nM) increased neutrophil basal viability by 34 and 26% (raising it from 43 to 58 and 55%) respectively. Treatment with Ang1 (0.001-50 nM) increased neutrophil viability by up to 41%, while Ang2 had no significant effect. Combination of IL-8 (25 nM) or PAF (100 nM) with Ang1 (10 nM) further increased neutrophil viability by 56 and 60% respectively. We also observed that Ang1, but not Ang2 can promote IL-8 release and that a pretreatment of the neutrophils with blocking anti-IL-8 antibodies inhibited the anti-apoptotic effect of IL-8 and Ang1 by 92 and 81% respectively. Pretreatment with a selective PAF receptor antagonist (BN 52021), did abrogate PAF pro-survival activity, without affecting Ang1-induced neutrophil viability. Our data are the first ones to report Ang1 pro-survival activity on neutrophils, which is mainly driven through IL-8 release.

Angiopoietin-1 but not angiopoietin-2 induces IL-8 synthesis and release by human neutrophils.

We previously reported Tie2 receptor expression on human neutrophils, which promote chemotactic activities upon activation by both angiopoietins (Ang1 and Ang2). Moreover, we observed that neutrophil pretreatment with Ang1 or Ang2 enhances interleukin-8 (IL-8) chemotactic effect. Therefore, we assessed the capacity of Ang1 and/or Ang2 to modulate neutrophil IL-8 synthesis and release. Neutrophils isolated from healthy donors were stimulated in a time- (1-6 h) and concentration-(10(-10) -10(-8) M) dependent manner with both angiopoietins. IL-8 mRNA production was measured by RT-qPCR, whereas its protein synthesis and release from neutrophils was assessed by ELISA. Ang1 (10(-8) M) induced a significant and maximal increase of IL-8 mRNA (4.7-fold) within 1 h, and promoted maximal IL-8 protein synthesis (3.6-fold) and release (5.5-fold) within 2 h as compared to control PBS-treated neutrophils. Treatment with Ang2 alone did not modulate IL-8 synthesis or release, and its combination to Ang1 did not affect Ang1 activity. Neutrophil pretreatment with a protein synthesis inhibitor (CHX) increased IL-8 mRNA synthesis by 18-fold, and reduced Ang1-mediated IL-8 protein synthesis and release by 96% and 92%, respectively. Pretreatment with a transcription inhibitor (ActD) reduced IL-8 mRNA synthesis by 54% and IL-8 protein synthesis and release by 52% and 79%, respectively. Using specific kinase inhibitors, we observed that Ang1-driven IL-8 mRNA and protein synthesis is p42/44 MAPK-dependent and -independent from p38 MAPK and PI3K activity. Our study is the first to report the capacity of Ang1 (as opposed to Ang2) to promote neutrophil IL-8 synthesis and release through the activation of p42/44 MAPK pathway.

Neutrophils and Circulating Inflammatory Biomarkers in Diabetes Mellitus and Heart Failure With Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is characterized by low-grade chronic inflammation, which could be exacerbated by type 2 diabetes mellitus (DM). We hypothesized that neutrophils in patients with DM and patients with HFpEF with/without DM contribute to low-grade inflammation through the release of pro-inflammatory cytokines. Venous blood was withdrawn from patients with DM (n = 22), HFpEF (n = 15), HFpEF with DM (n = 13), and healthy controls (CTL) (n = 21). Levels of circulating cytokines and in vitro cytokines released by isolated neutrophils were assessed by enzyme-linked immunosorbent assay. Compared with CTL, there was a significant decrease in circulating nitric oxide in patients with DM (p ≤0.001), HFpEF (p ≤0.05), and HFpEF with DM (p ≤0.001) up to 44%. Circulating soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 levels increased (up to 2.5-fold and 1.9-fold, respectively; p ≤0.001) in patients with HFpEF and patients with HFpEF and DM, whereas soluble E-selectin only increased in patients with HFpEF and DM (1.4-fold, p ≤0.001). Circulating vascular endothelial growth factor levels were similar in CTL and patients with DM but were decreased in patients with HFpEF with/without DM (up to 94%; p ≤0.001). Circulating C-reactive protein, interleukin (IL)-8, IL-6, and IL-receptor antagonist increased in all patient groups with a maximum of 3.3-fold, 4.7-fold, 4.8-fold, and 1.6-fold, respectively, in patients with HFpEF and patients with DM. In vitro, lipopolysaccharide increased neutrophils IL-6 release from HFpEF with DM (3.7-fold; p ≤0.001), and IL-8 release from DM and HFpEF with DM versus CTL (2.8-fold and 10.1-fold, respectively; p ≤0.001). IL-1 receptor antagonist and vascular endothelial growth factor release from HFpEF neutrophils significantly decreased up to 87.0% and 92.2%, respectively, versus CTL. Neutrophils from patients with DM and HFpEF release more cytokines than CTL. This increase in pro-inflammatory status may explain the greater event rate in patients with HFpEF and DM.

Acute effect of passive heat exposure on markers of cardiometabolic function in adults with type 2 diabetes mellitus.

Heat therapy is a promising strategy to improve cardiometabolic health. This study evaluated the acute physiological responses to hot water immersion in adults with type 2 diabetes mellitus (T2DM). On separate days in randomized order, 13 adults with T2DM [8 males/5 females, 62 ± 12 yr, body mass index (BMI): 30.1 ± 4.6 kg/m2] were immersed in thermoneutral (34°C, 90 min) or hot (41°C, core temperature ≥38.5°C for 60 min) water. Insulin sensitivity was quantified via the minimal oral model during an oral glucose tolerance test (OGTT) performed 60 min after immersion. Brachial artery flow-mediated dilation (FMD) and reactive hyperemia were evaluated before and 40 min after immersion. Blood samples were drawn to quantify protein concentrations and mRNA levels of HSP70 and HSP90, and circulating concentrations of cytokines. Relative to thermoneutral water immersion, hot water immersion increased core temperature (+1.66°C [+1.47, +1.87], P < 0.01), heart rate (+34 beats/min [+24, +44], P < 0.01), antegrade shear rate (+96 s-1 [+57, +134], P < 0.01), and IL-6 (+1.38 pg/mL [+0.31, +2.45], P = 0.01). Hot water immersion did not exert an acute change in insulin sensitivity (-0.3 dL/kg/min/µU/mL [-0.9, +0.2], P = 0.18), FMD (-1.0% [-3.6, +1.6], P = 0.56), peak (+0.36 mL/min/mmHg [-0.71, +1.43], P = 0.64), and total (+0.11 mL/min/mmHg × min [-0.46, +0.68], P = 0.87) reactive hyperemia. There was also no change in eHSP70 (P = 0.64), iHSP70 (P = 0.06), eHSP90 (P = 0.80), iHSP90 (P = 0.51), IL1-RA (P = 0.11), GLP-1 (P = 0.59), and NF-κB (P = 0.56) after hot water immersion. The physiological responses elicited by hot water immersion do not acutely improve markers of cardiometabolic function in adults with T2DM.NEW & NOTEWORTHY Heat therapy has been shown to improve markers of cardiometabolic health in preclinical and clinical studies. However, the effects of heat therapy in individuals with type 2 diabetes mellitus (T2DM) remain understudied. We examined the acute effect of hot water immersion on glucose tolerance, flow-mediated dilation, reactive hyperemia, inflammatory markers, and heat shock proteins in adults with T2DM. Hot water immersion did not acutely improve the markers studied.

Correlation between Neutrophil Extracellular Traps (NETs) Expression and Primary Graft Dysfunction Following Human Lung Transplantation.

Primary graft dysfunction (PGD) is characterized by alveolar epithelial and vascular endothelial damage and inflammation, lung edema and hypoxemia. Up to one-third of recipients develop the most severe form of PGD (Grade 3; PGD3). Animal studies suggest that neutrophils contribute to the inflammatory process through neutrophil extracellular traps (NETs) release (NETosis). NETs are composed of DNA filaments decorated with granular proteins contributing to vascular occlusion associated with PGD. The main objective was to correlate NETosis in PGD3 (n = 9) versus non-PGD3 (n = 27) recipients in an exploratory study. Clinical data and blood samples were collected from donors and recipients pre-, intra- and postoperatively (up to 72 h). Inflammatory inducers of NETs' release (IL-8, IL-6 and C-reactive protein [CRP]) and components (myeloperoxidase [MPO], MPO-DNA complexes and cell-free DNA [cfDNA]) were quantified by ELISA. When available, histology, immunohistochemistry and immunofluorescence techniques were performed on lung biopsies from donor grafts collected during the surgery to evaluate the presence of activated neutrophils and NETs. Lung biopsies from donor grafts collected during transplantation presented various degrees of vascular occlusion including neutrophils undergoing NETosis. Additionally, in recipients intra- and postoperatively, circulating inflammatory (IL-6, IL-8) and NETosis biomarkers (MPO-DNA, MPO, cfDNA) were up to 4-fold higher in PGD3 recipients compared to non-PGD3 (p = 0.041 to 0.001). In summary, perioperative elevation of NETosis biomarkers is associated with PGD3 following human lung transplantation and these biomarkers might serve to identify recipients at risk of PGD3 and initiate preventive therapies.

Neutrophils pro-inflammatory and anti-inflammatory cytokine release in patients with heart failure and reduced ejection fraction.

AIMS: Heart failure with reduced ejection fraction (HFrEF) is characterized by sub-clinical inflammation. Changes in selected biomarkers of inflammation concomitant with the release of pro-inflammatory and anti-inflammatory cytokines by neutrophils have not been investigated in patients with HFrEF. METHODS AND RESULTS: Fifty-two patients, aged 68.8 ± 1.7 years, with HFrEF and left ventricular ejection fraction 28.7 ± 1.0%, and 21 healthy controls (CTL) were recruited. Twenty-five HF patients had type 2 diabetes. Venous blood samples from HF and CTL were collected once. Neutrophil-derived pro-inflammatory and anti-inflammatory cytokine levels were assessed in plasma by ELISA. Plasma biomarkers assessed included: C-reactive protein (CRP), vascular endothelial growth factor (VEGF), interleukins (IL)-6, -8, -1 receptor antagonist (-1RA), nitric oxide (NO), soluble intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule 1 (sVCAM-1) and E-Selectin (sE-Sel). Neutrophils were isolated and stimulated with various agonists to promote VEGF, IL-6, IL-8, and IL-1RA release. Compared with CTL, HFrEF patients showed a marked decrease in circulating VEGF [178.0 (interquartile range; IQR 99.6; 239.2) vs. 16.2 (IQR 9.3; 20.2) pg/mL, P ≤ 0.001] and NO [45.2 (IQR 42.1; 57.6) vs. 40.6 (IQR 30.4; 47.1) pg/mL, P = 0.0234]. All other circulating biomarkers were significantly elevated. Neutrophils isolated from patients with HFrEF exhibited a greater IL-8 release in response to LPS [1.2 ± 0.1 (CTL); 10.4 ± 1.6 ng/mL (HFrEF) and 12.4 ± 1.6 ng/mL (HFrEF and DM), P ≤ 0.001]. IL-6 release in response to LPS was not changed in HFrEF patients without diabetes, whereas it was significantly increased in patients with HFrEF and diabetes [46.7 ± 3.9 (CTL) vs. 165.8 ± 48.0 pg/mL (HFrEF), P = 0.1713 and vs. 397.7 ± 67.4 pg/mL (HFrEF and DM), P ≤ 0.001]. In contrast, the release of VEGF and IL-1RA was significantly reduced in HFrEF (VEGF; TNF-α: 38.6 ± 3.1 and LPS: 25.3 ± 2.6 pg/mL; IL1RA; TNF-α: 0.6 ± 0.04 and LPS: 0.3 ± 0.02 ng/mL) compared with CTL (VEGF; TNF-α: 60.0 ± 9.4 and LPS: 41.2 ± 5.9 pg/mL; IL1RA; TNF-α: 3.3 ± 0.2 and LPS: 2.3 ± 0.1 ng/mL). CONCLUSIONS: Patients with HFrEF exhibit a significant decrease in circulating VEGF. The release of VEGF and both pro-inflammatory and anti-inflammatory cytokines from the stimulated neutrophils is markedly altered in these patients. The clinical significance of these findings deserves further investigation.

Acute Vascular Benefits of Finnish Sauna Bathing in Patients With Stable Coronary Artery Disease.

BACKGROUND: Finnish sauna bathing habits are associated with a decreased risk of cardiovascular mortality. The physiologic adaptations mediating this association remain to be fully elucidated. This study tested the hypothesis that Finnish sauna bathing acutely improves peripheral flow-mediated dilation (FMD) in middle-aged and older adults with stable coronary artery disease (CAD). METHODS: Twenty-two adults (20 male, 2 female; 67 ± 10 years) with stable CAD underwent 2 periods of 10 minutes in a Finnish sauna (81.3 ± 2.7°C, 23 ± 3% humidity) separated by 10 minutes of thermoneutral rest. Before and 51 ± 8 minutes after sauna bathing, brachial artery FMD and postocclusive reactive hyperemia (PORH) were evaluated by means of Doppler ultrasound. RESULTS: Sauna bathing increased core temperature (mean +0.66°C [95% CI 0.54-0.77], P < 0.01) and heart rate (+27 beats/min [24-29], P < 0.01), and decreased systolic (-19 mm Hg [-31 to -6]; P < 0.01) and diastolic (-6 mm Hg [-11 to -1], P < 0.01) blood pressures. Brachial artery FMD was greater after sauna bathing (+1.21% [0.16-2.26], P = 0.04), whereas PORH was unchanged (peak: +0.51 mL/min/mm Hg [-0.13 to 1.15], P = 0.11; area under the curve: +0.21 mL/mm Hg [-0.12 to 0.54]; P = 0.19). CONCLUSIONS: A typical Finnish sauna bathing session acutely improves peripheral FMD in middle-aged and older adults with stable CAD.

Endothelial progenitor cells bind and inhibit platelet function and thrombus formation.

BACKGROUND: Interactions of endothelial progenitor cells (EPCs) with vascular and blood cells contribute to vascular homeostasis. Although platelets promote the homing of EPCs to sites of vascular injury and their differentiation into endothelial cells, the functional consequences of such interactions on platelets remain unknown. Herein, we addressed the interactions between EPCs and platelets and their impact on platelet function and thrombus formation. METHODS AND RESULTS: Cultured on fibronectin in conditioned media, human peripheral blood mononuclear cells differentiated, within 10 days of culture, into EPCs, which uptake acetylated low-density lipoprotein, bind ulex-lectin, lack monocyte/leukocyte markers (CD14, P-selectin glycoprotein ligand-1, L-selectin), express progenitor/endothelial markers (CD34, vascular endothelial growth factor receptor-2, von Willebrand factor, and vascular endothelial cadherin), and proliferate in culture. These EPCs bound activated platelets via CD62P and inhibited its translocation, glycoprotein IIb/IIIa activation, aggregation, and adhesion to collagen, mainly via prostacyclin secretion. Indeed, this was associated with upregulation of cyclooxygenase-2 and inducible nitric oxide synthase. However, the effects on platelets in vitro were reversed by cyclooxygenase and cyclooxygenase-2 inhibition but not by nitric oxide or inducible nitric oxide synthase inhibition. Moreover, in a ferric chloride-induced murine arterial thrombosis model, injection of EPCs led to their incorporation into sites of injury and impaired thrombus formation, leading to an incomplete occlusion with 50% residual flow. CONCLUSIONS: Peripheral blood mononuclear cell-derived EPCs bind platelets via CD62P and inhibit platelet activation, aggregation, adhesion to collagen, and thrombus formation, predominantly via upregulation of cyclooxygenase-2 and secretion of prostacyclin. These findings add new insights into the biology of EPCs and define their potential roles in regulating platelet function and thrombosis.

Identification of VEGF receptor-2 tyrosine phosphorylation sites involved in VEGF-mediated endothelial platelet-activating factor synthesis.

Vascular endothelial growth factor (VEGF)-mediated inflammation requires the synthesis of acute platelet-activating factor (PAF) by endothelial cells (ECs). We previously reported that VEGF-mediated PAF synthesis involves the activation of the homodimeric tyrosine kinase receptor VEGFR-2/R-2, leading to the recruitment of p38 and p42/p44 mitogen-activated protein kinases (MAPKs) and activation of secreted group V phospholipase A2 (sPLA2-V). We have also reported that VEGF-A165-mediated prostacyclin (PGI2) synthesis requires VEGFR-1/R-2 heterodimeric receptor activation. Selective activation of VEGF receptors can coordinate the synthesis of pro-PAF and anti-PGI2 inflammatory factors. It is unknown which VEGFR-2 tyrosine phosphorylation site(s) contribute(s) to PAF synthesis. Bovine aortic endothelial cells (BAECs) were transfected with pcDNA vectors encoding for native VEGF receptor-2 (VEGFR-2) cDNA or VEGFR-2 cDNA containing tyrosine phosphorylation sites mutated into phenylalanine residues (Y801F, Y1059F, Y1175F, Y1214F); an empty pcDNA vector was used as a negative control. Treatment of pcDNA-transfected BAECs with VEGF (10⁻9 mol/L) for 15 min increased PAF synthesis by 180%. In BAECs transfected with pcDNA vectors encoding mutated Y801F, Y1059F, Y1175F, or Y1214F VEGFR-2 cDNA, we observed a marked reduction of VEGF-mediated PAF synthesis by 38%, 46%, 69%, and 31%, respectively, compared with BAECs transfected with pcDNA vector encoding VEGFR-2 cDNA. Our data provide a novel insight as to the mechanisms by which VEGF promotes PAF synthesis.

Impact of Finnish sauna bathing on circulating markers of inflammation in healthy middle-aged and older adults: A crossover study.

OBJECTIVES: Finnish sauna bathing is associated with a reduced risk of adverse health outcomes. The acute physiological responses elicited by Finnish sauna bathing that could explain this association remain understudied. This study characterized the acute effect of Finnish sauna bathing on circulating markers of inflammation in healthy middle-aged and older adults. DESIGN: With the use of a crossover study design, 20 healthy middle-aged and older adults (9 men/11 women, 66 ±â€¯6 years old) performed 3 interventions in random order: 1) 1 x 10 min of Finnish sauna bathing (80 °C, 20 % humidity); 2) 2 x 10 min of Finnish sauna bathing; 3) a time-control period during which participants sat outside of the sauna for 10 min. MAIN OUTCOMES: Venous blood samples were obtained before (≤15 min) and after (∼65 min) each intervention to determine circulating concentrations of interleukin 6 (IL-6), interleukin 1 receptor antagonist (IL-1RA), and C-reactive protein (CRP). RESULTS: IL-6 increased in response to 2 x 10 min of sauna bathing (+0.92 pg/mL [+0.16, +1.68], P = 0.02), but not following the 1 x 10 min session (+0.17 pg/mL [-0.13, +0.47], P = 0.26). IL1-RA increased during the 1 x 10 min (+51.27 pg/mL [+20.89, +81.65], P < 0.01) and 2 x 10 min (+30.78 pg/mL [+3.44, +58.12], P = 0.03) sessions. CRP did not change in response to either sauna session (P = 0.34). CONCLUSION: These results demonstrate that typical Finnish sauna bathing sessions acutely increase IL-6 and IL1-RA in healthy middle-aged and older adults.

Increased Circulating Levels of Neutrophil Extracellular Traps During Cardiopulmonary Bypass.

BACKGROUND: The intensity of inflammatory response triggered by cardiopulmonary bypass (CPB) during cardiac surgery has been associated with adverse outcomes. Neutrophils might contribute to organ injury through the liberation of DNA histone-based structures named "neutrophil extracellular traps" (NETs). Our objective was to assess circulating NETs levels before and after cardiac surgery in low-risk and high-risk patients. METHODS: This prospective cohort study included 2 groups of patients undergoing elective cardiac surgery with the use of CPB. The first group consisted of low-risk patients (European System for Cardiac Operative Risk Evaluation II ≤ 1%), and the second group included high-risk patients (European System for Cardiac Operative Risk Evaluation II ≥ 5%). Blood samples were drawn pre-CPB and 3 hours post-CPB separation. Measurements of circulating NETs, interleukin-6, C-reactive protein, myeloperoxidase, citrullinated histone 3, and pentraxin-related protein 3 levels were performed at each time point. RESULTS: Twenty-four patients, 12 high-risk and 12 low-risk patients, were included. Circulating NETs measurements changed from a median of 0.054 before CPB to 0.084 at 3 hours post-CPB separation, with a median increase of 0.037 (P < 0.001) per patient. No difference was noted between the high-risk and low-risk groups. A linear relationship was found between the circulating NETs measurements 3 hours post-CPB and CPB duration (ß = 0.047; confidence interval, 0.012-0.081; P = 0.01 R2 = 0.27). A correlation was found between the change in NETs with citrullinated histone 3 and myeloperoxidase levels, but not between NETs and other inflammatory biomarkers. CONCLUSIONS: Circulating NETs measurements increases during cardiac surgery with postsurgical levels proportional to CPB duration. The clinical significance of NETs production during cardiac surgery should be further investigated.

CONTEXTE: L'intensité de la réponse inflammatoire déclenchée par la circulation extracorporelle en cours de chirurgie cardiaque a été associée à des résultats défavorables. Les neutrophiles pourraient contribuer à des lésions organiques par la libération de structures d'ADN lié à des histones appelées « pièges extracellulaires des neutrophiles ¼ (ou NETs, de l'anglais neutrophil extracellular traps). Nous nous sommes donné pour objectif d'évaluer les taux de ces pièges extracellulaires dans la circulation avant et après la chirurgie cardiaque chez des patients exposés à des risques faibles et à des risques élevés. MÉTHODOLOGIE: Cette étude prospective de cohortes a été menée chez deux groupes de patients subissant une chirurgie cardiaque non urgente au cours de laquelle nous avons eu recours à la circulation extracorporelle. Le premier groupe était composé de patients exposés à un faible risque (EuroSCORE II [European System for Cardiac Operative Risk Evaluation II] ≤ 1 %), et le second, de patients exposés à un risque élevé (EuroSCORE II ≥ 5 %). Des échantillons sanguins étaient prélevés avant la mise sous circulation extracorporelle, puis 3 heures après le sevrage de la circulation extracorporelle. Les taux de NETs circulants, d'interleukine-6, de protéine C réactive, de myéloperoxydase, d'histones 3 citrullinées et de protéines apparentées à la pentraxine 3 ont été mesurés à chaque point d'évaluation. RÉSULTATS: Les données obtenues chez vingt-quatre patients, 12 dans le groupe à risque élevé et 12 dans le groupe à faible risque, ont été incluses dans l'analyse. Le taux médian de NETs circulants est passé de 0,054 avant la circulation extracorporelle à 0,084 trois heures après le sevrage, avec une augmentation médiane de 0,037 (p < 0,001) par patient. Aucune différence n'a été notée entre les deux groupes. Une relation linéaire a été observée entre la mesure du taux de NETs circulants 3 heures après le sevrage et la durée de la circulation extracorporelle (ß = 0,047; intervalle de confiance : 0,012-0,081; p = 0,01; R2= 0,27). Une corrélation a été notée entre la variation du taux de NETs comportant des histones 3 citrullinés et du taux de myéloperoxydase, mais pas entre le taux de NETs et ceux des autres biomarqueurs de l'inflammation. CONCLUSIONS: Le taux de NETs circulants augmente pendant une chirurgie cardiaque, le taux après la chirurgie étant proportionnel à la durée de la circulation extracorporelle. L'importance clinique de la production de NETs pendant la chirurgie cardiaque doit faire l'objet d'études plus approfondies.

Colchicine reduces lung injury in experimental acute respiratory distress syndrome.

The acute respiratory distress syndrome (ARDS) is characterized by intense dysregulated inflammation leading to acute lung injury (ALI) and respiratory failure. There are no effective pharmacologic therapies for ARDS. Colchicine is a low-cost, widely available drug, effective in the treatment of inflammatory conditions. We studied the effects of colchicine pre-treatment on oleic acid-induced ARDS in rats. Rats were treated with colchicine (1 mg/kg) or placebo for three days prior to intravenous oleic acid-induced ALI (150 mg/kg). Four hours later they were studied and compared to a sham group. Colchicine reduced the area of histological lung injury by 61%, reduced lung edema, and markedly improved oxygenation by increasing PaO2/FiO2 from 66 ± 13 mmHg (mean ± SEM) to 246 ± 45 mmHg compared to 380 ± 18 mmHg in sham animals. Colchicine also reduced PaCO2 and respiratory acidosis. Lung neutrophil recruitment, assessed by myeloperoxidase immunostaining, was greatly increased after injury from 1.16 ± 0.19% to 8.86 ± 0.66% and significantly reduced by colchicine to 5.95 ± 1.13%. Increased lung NETosis was also reduced by therapy. Circulating leukocytosis after ALI was not reduced by colchicine therapy, but neutrophils reactivity and CD4 and CD8 cell surface expression on lymphocyte populations were restored. Colchicine reduces ALI and respiratory failure in experimental ARDS in relation with reduced lung neutrophil recruitment and reduced circulating leukocyte activation. This study supports the clinical development of colchicine for the prevention of ARDS in conditions causing ALI.

Expression and release of angiopoietin-1 from human neutrophils: intracellular mechanisms.

We recently demonstrated that Tie2 receptor activation on human neutrophils by both angiopoietins (Ang1 and Ang2) promoted platelet-activating factor synthesis, beta(2)-integrin activation, and cell migration. Herein, we wanted to assess if human neutrophils express angiopoietins and further delineate their mechanisms of release. Employing Reverse transcriptase-polymerase chain reaction, Real time quantitative transcriptase-polymerase chain reaction, FACScan analysis and ELISA approaches, we observed that neutrophils express Ang1 but not Ang2. For each condition, vascular endothelial growth factor (VEGF) detection was performed as positive control. Using nitrogen cavitation, we observed that Ang1 is localized in the cytosolic fraction whereas VEGF is found in beta-granules. Treatment of neutrophils with phorbol myristate acetate (PMA), N-Formyl-Met-Leu-Phe (fMLP) and tumor necrosis factor-alpha (TNF-alpha) induced VEGF release. Maximal effect was observed with PMA (80 nM) stimulation inducing a complete release of VEGF content (565 +/- 100 pg/ml; 6 x 10(6) neutrophils), corresponding to a 18.9-fold increase as compared to phosphate buffer saline (PBS) treated neutrophils. By contrast, only a treatment with PMA (80 nM) induced Ang1 release. PMA treatment induced also a complete release of Ang1 (661 +/- 148 pg/ml; 6 x 10(6) neutrophils), corresponding to 2.8-fold increase as compared to PBS-treated neutrophils. In both cases, PMA-mediated release of VEGF and Ang1 was nearly maximal by 15 min. Finally, we observed that the induction of Ang1 release was calcium-independent whereas VEGF release was not. These data demonstrate the capacity of human neutrophils to synthesize Ang1, which is stored and released differently as compared to VEGF. These data suggest a different cascade of events regarding the distribution of selected growth factors during inflammation and angiogenesis.

Angiopoietin-mediated endothelial P-selectin translocation: cell signaling mechanisms.

Recently identified, angiopoietin-1 (Ang1) and -2 (Ang2) bind to the tyrosine kinase receptor Tie2 and contribute to orchestrate blood vessel formation during angiogenesis. Ang1 mediates vessel maturation and integrity by favoring the recruitment of pericytes and smooth muscle cells. Ang2, initially identified as a Tie2 antagonist, may under certain circumstances, induce Tie2 phosphorylation and biological activities. As inflammation exists in a mutually dependent association with angiogenesis, we sought to determine if Ang1 and/or Ang2 could modulate proinflammatory activities, namely P-selectin translocation, in bovine aortic endothelial cells (EC) and dissect the mechanisms implicated. P-selectin, an adhesion molecule found in the Weibel-Palade bodies of EC, is translocated rapidly to the cell surface upon EC activation during inflammatory processes. Herein, we report that Ang1 and Ang2 (1 nM) are capable of mediating a rapid Tie2 phosphorylation as well as a rapid and transient endothelial P-selectin translocation maximal within 7.5 min (125% and 100% increase, respectively, over control values). In addition, we demonstrate for the first time that angiopoietin-mediated endothelial P-selectin translocation is calcium-dependent and regulated through phospholipase C-gamma activation.

CRP Induces NETosis in Heart Failure Patients with or without Diabetes.

C-reactive protein (CRP) is recognized as a biomarker of chronic, low-grade inflammation associated with vascular disorders. Lately, the role of neutrophils and neutrophil extracellular traps (NETs) has been investigated as a potential source of chronic inflammation and cardiovascular complications. This study investigated NETs as a marker of inflammation in patients with symptomatic heart failure (HF) with or without type 2 diabetes (T2DM) and examined the correlation between NETs and CRP. We performed a noninterventional study including patients with HF with or without T2DM, T2DM, and a healthy control (HC) group. NETs and other inflammatory markers in serum were measured by ELISA. The release of NETs (NETosis) in vitro under various stimuli was measured by confocal microscopy. The levels of NETs in the serum of HF patients were significantly higher compared with HC (112%). Serum CRP concentrations were significantly increased in HF and HF plus T2DM patients compared with HC, and a positive correlation was observed between serum CRP and NETs levels. Neutrophils from HF and HF plus T2DM patients underwent in vitro NETs release faster than T2DM and HC without any stimuli. In vitro, serum collected from the HF and the HF plus T2DM group induced NETosis in healthy neutrophils significantly more when compared with HC and T2DM, which was prevented by depletion from CRP. We confirmed in vitro that CRP induces a concentration-dependent NETs synthesis. This study proposes a mechanism by which CRP increases the risk of future cardiovascular events and supports mounting evidences on the role of neutrophils in chronic low-grade inflammation associated with HF.