Attachment Of Leukocytes Research Articles

The role of adipose tissue cell elements in the regulation of the nitroxidergic system and possible ways of pharmacological modulation

Endothelial dysfunction is characterized by a decrease in the bioavailability of the vasodilator – nitric oxide (NO), and an increase in the level of vasoconstrictor substances. This imbalance leads to vasoconstriction, leukocyte attachment and inflammatory reactions in the vascular wall, atherosclerosis and thrombosis. The aim: to evaluate the role of adipose tissue elements in the regulation of parameters of the nitroxidergic system under hypoxia conditions. Materials and methods. The studies were carried out on 30 adult white male Wistar rats. All animals were randomly assigned and divided into groups: a control group (15 rats), type 2 diabetes mellitus (T2DM) was induced in the animals of the second group (15 rats). Isolated fragments of the popliteal arteries (PA) and intrapulmonary artery (IPA) were cleared of perivascular adipose tissue (PVAT-) or left uncleaned (PVAT+) and cut into rings. The simulation of acute hypoxia with further study of medical agents were performed. Results. The PA and IPA with PVAT responded to acute hypoxia with vasoconstriction – an increase in the amplitude of contraction in the first and second phases, and after removing PVAT, they responded with a decrease in the maximum amplitude of contraction by 3.4 times in the 1st phase and an increase in amplitude by 1.8 times in the 2nd phase. Perfusion with Angiolin reduced 2nd phase of HV of the PA and IPA. Adding a combination of Thiotriazoline and L-arginine (1:4) to a solution for perfusion of fragments of arteries of animals with T2DM, causes a significant increase in constrictor reactions in both the 1st and 2nd phases of HV, regardless of presence of perivascular adipose tissue. Conclusions. The presence of PVAT affects the HV of arteries, both in normal and in T2DM. The possibilities of ways of pharmacological modulation of the nitroxidergic system depending on the state of PVAT were determined.

Hypercholesterolemia exacerbates in-stent restenosis in rabbits: Studies of the mitigating effect of stent surface modification with a CD47-derived peptide

Background and aimsHypercholesterolemia (HC) has previously been shown to augment the restenotic response in animal models and humans. However, the mechanistic aspects of in-stent restenosis (ISR) on a hypercholesterolemic background, including potential augmentation of systemic and local inflammation precipitated by HC, are not completely understood. CD47 is a transmembrane protein known to abort crucial inflammatory pathways. Our studies have examined the interrelation between HC, inflammation, and ISR and investigated the therapeutic potential of stents coated with a CD47-derived peptide (pepCD47) in the hypercholesterolemic rabbit model. MethodsPepCD47 was immobilized on metal foils and stents using polybisphosphonate coordination chemistry and pyridyldithio/thiol conjugation. Cytokine expression in buffy coat-derived cells cultured over bare metal (BM) and pepCD47-derivatized foils demonstrated an M2/M1 macrophage shift with pepCD47 coating. HC and normocholesterolemic (NC) rabbit cohorts underwent bilateral implantation of BM and pepCD47 stents (HC) or BM stents only (NC) in the iliac location. ResultsA 40 % inhibition of cell attachment to pepCD47-modified compared to BM surfaces was observed. HC increased neointimal growth at 4 weeks post BM stenting. These untoward outcomes were mitigated in hypercholesterolemic rabbits treated with pepCD47-derivatized stents. Compared to NC animals, inflammatory cytokine immunopositivity and macrophage infiltration of peri-strut areas increased in HC animals and were attenuated in HC rabbits treated with pepCD47 stents. ConclusionsAugmented inflammatory responses underlie severe ISR morphology in hypercholesterolemic rabbits. Blockage of initial platelet and leukocyte attachment to stent struts through CD47 functionalization of stents mitigates the pro-restenotic effects of hypercholesterolemia.

Neflamapimod inhibits endothelial cell activation, adhesion molecule expression, leukocyte attachment and vascular inflammation by inhibiting p38 MAPKα and NF-κB signaling

Neflamapimod, a selective inhibitor of the alpha isoform of p38 mitogen-activated protein kinase (MAPKα), was investigated for its potential to inhibit lipopolysaccharide (LPS)-induced activation of endothelial cells (ECs), adhesion molecule induction, and subsequent leukocyte attachment to EC monolayers. These events are known to contribute to vascular inflammation and cardiovascular dysfunction. Our results demonstrate that LPS treatment of cultured ECs and rats leads to significant upregulation of adhesion molecules, both in vitro and in vivo, which can be effectively inhibited by neflamapimod treatment. Western blotting data further reveals that neflamapimod inhibits LPS-induced phosphorylation of p38 MAPKα and the activation of NF-κB signaling in ECs. Additionally, leukocyte adhesion assays demonstrate a substantial reduction in leukocyte attachment to cultured ECs and the aorta lumen of rats treated with neflamapimod. Consistent with vascular inflammation, LPS-treated rat arteries exhibit significantly diminished vasodilation response to acetylcholine, however, arteries from rats treated with neflamapimod maintain their vasodilation capacity, demonstrating its ability to limit LPS-induced vascular inflammation. Overall, our data demonstrate that neflamapimod effectively inhibits endothelium activation, adhesion molecule expression, and leukocyte attachment, thereby reducing vascular inflammation.

Beneficial effects of PCSK9 inhibition with alirocumab in familial hypercholesterolemia involve modulation of new immune players.

Familial hypercholesterolemia (FH) is associated with low-grade systemic inflammation, a key driver of premature atherosclerosis. We investigated the effects of inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9) function on inflammatory state, endothelial dysfunction and cardiovascular outcomes in patients with FH. Fourteen patients with FH were evaluated before and 8 weeks after administration of a PCSK9 blocking monoclonal antibody (alirocumab, 150 mg/subcutaneous/14 days). In vivo and ex vivo analysis revealed that alirocumab blunted the attachment of leukocytes to TNFα-stimulated human umbilical arterial endothelial cells (HUAEC) and suppressed the activation of platelets and most leukocyte subsets, which was accompanied by the diminished expression of CX3CR1, CXCR6 and CCR2 on several leukocyte subpopulations. By contrast, T-regulatory cell activation was enhanced by alirocumab treatment, which also elevated anti-inflammatory IL-10 plasma levels and lowered circulating pro-inflammatory cytokines. Plasma levels of IFNγ positively correlated with levels of total and LDL-cholesterol, whereas circulating IL-10 levels negatively correlated with these key lipid parameters. In vitro analysis revealed that TNFα stimulation of HUAEC increased the expression of PCSK9, whereas endothelial PCSK9 silencing reduced TNFα-induced mononuclear cell adhesion mediated by Nox5 up-regulation and p38-MAPK/NFκB activation, concomitant with reduced SREBP2 expression. PCSK9 silencing also decreased endothelial CX3CL1 and CXCL16 expression and chemokine generation. In conclusion, PCSK9 inhibition impairs systemic inflammation and endothelial dysfunction by constraining leukocyte-endothelium interactions. PCSK9 blockade may constitute a new therapeutic approach to control the inflammatory state associated with FH, preventing further cardiovascular events in this cardiometabolic disorder.

Leukotriene D4 Upregulates Oxidized Low-Density Lipoprotein Receptor 1 and CD36 to Enhance Oxidized LDL Uptake and Phagocytosis in Macrophages Through Cysteinyl Leukotriene Receptor 1.

Endothelial permeability, leukocyte attachment, and unregulated oxidized LDL (oxLDL) uptake by macrophages leading to the formation of foam cells are all vital in the initiation and progression of atherosclerosis. During inflammation, several inflammatory mediators regulate this process through the expression of distinct oxLDL binding cell surface receptors on macrophages. We have previously shown that Leukotriene D4 (LTD4) promotes endothelial dysfunction, increasing endothelial permeability and enhancing TNFα-mediated attachment of monocytes to endothelium, which hints at its possible role in atherosclerosis. Here we analyzed the effect of LTD4 on macrophage function. Macrophages mainly express CysLT1R and flux calcium in response to LTD4. Further, LTD4 potentiates phagocytosis in macrophages as revealed by the uptake of zymosan particles. Notably, LTD4 augmented macrophage phagocytosis and oxLDL uptake which is sensitive to MK-571 [Montelukast (MK)], a CysLT1R-specific antagonist. Mechanistically, LTD4 upregulated two receptors central to foam cell formation, oxidized low-density lipoprotein receptor-1 (OLR1/LOX-1), and CD36 in a time and dose-dependent manner. Finally, LTD4 enhanced the secretion of chemokines MCP-1 and MIP1β. Our results suggest that LTD4 contributes to atherosclerosis either through driving foam cell formation or recruitment of immune cells or both. CysLT1R antagonists are safely being used in the treatment of asthma, and the findings from the current study suggest that these can be re-purposed for the treatment of atherosclerosis.

Abstract 11439: CD47 Functionalization of Bare Metal Stents Reduces In-Stent Restenosis in Hypercholesterolemic Rabbits

Background: Inflammatory mechanisms, which can be affected by altered metabolic profiles such as hypercholesterolemia (HC), contribute to the pathophysiology of in-stent restenosis (ISR). CD47 is a transmembrane protein that is known to inhibit immune cell and platelet activation. Previously in a rat model, we showed that immobilizing peptide sequences of CD47 (pepCD47) to stainless steel (SS) stent surfaces decreased platelet and leukocyte association, and significantly reduced ISR. In these current studies, we use HC rabbits to test the hypothesis that the pepCD47-modified stents will reduce ISR in a pro-atherogenic phenotype. Methods: PepCD47 was attached to SS using polybisphosphonate coordination chemistry and pyridyldithio/thiol conjugation. Bare metal (BM) and pepCD47 SS foils (n=6) were exposed to anticoagulated blood from normocholesterolemic (NC) or HC rabbits for 1 hr. The relative abundance of the surface-associated cells was determined fluorimetrically. Rabbits (n=4) were fed a HC diet for 4 weeks prior to placing BMS or pepCD47 stents bilaterally in the iliac locations. The diet was continued until sacrifice (4 weeks). After chemical dissolution of the stent struts, the segments were paraffin embedded, sectioned, stained and assessed morphometrically. The prevalence of peri-strut macrophages was determined by immunohistochemistry (IHC) as a percentage of a strut circumference infiltrated with macrophages. Results: An 8% decrease of platelet and leukocyte attachment to a pepCD47-derivatized SS compared to BM foils (p=NS) was observed with NC blood, while a significant 35% decrease of cell attachment (p<0.002) was found between the pepCD47 and BM foils exposed to HC rabbit blood. Lumen area increased (25%) whereas the neointimal area, % stenosis and neointima to media ratio decreased (23%, 25%, and 25% p=0.04, respectively) in the arteries treated with pepCD47 stents compared to BMS controls. IHC showed a 34% reduction of macrophage infiltration in the peri-strut area (p=0.048). Conclusion: These results are the first to show the anti-restenotic properties of pepCD47 modified stents in a translational HC rabbit model. The anti-restenotic effects are likely due to CD47-mediated reduction of stent-triggered inflammation.

Heparanase is Involved in Leukocyte Migration.

Leukocyte migration is essential for exerting self-defense mechanisms. During the extravasation process, leukocytes transmigrate through the endothelial lining and the subendothelial basement membrane. Accumulating evidence supports the involvement of heparanase in this process. Altered cellular distribution resulting in relocalization of heparanase to the leading edge of migration is a key event to rapidly turn on the function of the enzyme during migration. This review presents current research investigating the cellular machinery that builds up a functional subcellular structure for leukocyte attachment to and degradation of the extracellular matrix. Recent advances in the understanding of the roles of heparanase in inflammatory diseases and pharmacological approaches to control heparanase-mediated actions during inflammation are also discussed.

Modular microfluidic systems cast from 3D-printed molds for imaging leukocyte adherence to differentially treated endothelial cultures

Microfluidic systems are very useful for in vitro studies of interactions between blood cells and vascular endothelial cells under flow, and several commercial solutions exist. However, the availability of customizable, user-designed devices is largely restricted to researchers with expertise in photolithography and access to clean room facilities. Here we describe a strategy for producing tailor-made modular microfluidic systems, cast in PDMS from 3D-printed molds, to facilitate studies of leukocyte adherence to endothelial cells. A dual-chamber barrier module was optimized for culturing two endothelial cell populations, separated by a 250 μm wide dividing wall, on a glass slide. In proof-of-principle experiments one endothelial population was activated by TNFα, while the other served as an internal control. The barrier module was thereafter replaced with a microfluidic flow module, enclosing both endothelial populations in a common channel. A suspension of fluorescently-labeled leukocytes was then perfused through the flow module and leukocyte interactions with control and TNFα-treated endothelial populations were monitored in the same field of view. Time-lapse microscopy analysis confirmed the preferential attachment of leukocytes to the TNFα-activated endothelial cells. We conclude that the functionality of these modular microfluidic systems makes it possible to seed and differentially activate adherent cell types, and conduct controlled side-by-side analysis of their capacity to interact with cells in suspension under flow. Furthermore, we outline a number of practical considerations and solutions associated with connecting and switching between the microfluidic modules, and the advantages of simultaneously and symmetrically analyzing control and experimental conditions in such a microfluidic system.

Chanzyme TRPM7 protects against cardiovascular inflammation and fibrosis.

AimsTransient Receptor Potential Melastatin 7 (TRPM7) cation channel is a chanzyme (channel + kinase) that influences cellular Mg2+ homeostasis and vascular signalling. However, the pathophysiological significance of TRPM7 in the cardiovascular system is unclear. The aim of this study was to investigate the role of this chanzyme in the cardiovascular system focusing on inflammation and fibrosis.Methods and resultsTRPM7-deficient mice with deletion of the kinase domain (TRPM7+/Δkinase) were studied and molecular mechanisms investigated in TRPM7+/Δkinase bone marrow-derived macrophages (BMDM) and co-culture systems with cardiac fibroblasts. TRPM7-deficient mice had significant cardiac hypertrophy, fibrosis, and inflammation. Cardiac collagen and fibronectin content, expression of pro-inflammatory mediators (SMAD3, TGFβ) and cytokines [interleukin (IL)-6, IL-10, IL-12, tumour necrosis factor-α] and phosphorylation of the pro-inflammatory signalling molecule Stat1, were increased in TRPM7+/Δkinase mice. These processes were associated with infiltration of inflammatory cells (F4/80+CD206+ cardiac macrophages) and increased galectin-3 expression. Cardiac [Mg2+]i, but not [Ca2+]i, was reduced in TRPM7+/Δkinase mice. Calpain, a downstream TRPM7 target, was upregulated (increased expression and activation) in TRPM7+/Δkinase hearts. Vascular functional and inflammatory responses, assessed in vivo by intra-vital microscopy, demonstrated impaired neutrophil rolling, increased neutrophil: endothelial attachment and transmigration of leucocytes in TRPM7+/Δkinase mice. TRPM7+/Δkinase BMDMs had increased levels of galectin-3, IL-10, and IL-6. In co-culture systems, TRPM7+/Δkinase macrophages increased expression of fibronectin, proliferating cell nuclear antigen, and TGFβ in cardiac fibroblasts from wild-type mice, effects ameliorated by MgCl2 treatment.ConclusionsWe identify a novel anti-inflammatory and anti-fibrotic role for TRPM7 and suggest that its protective effects are mediated, in part, through Mg2+-sensitive processes.

Macrocyclic lactone anthelmintic-induced leukocyte binding to Dirofilaria immitis microfilariae: Influence of the drug resistance status of the parasite

The macrocyclic lactone anthelmintics are the only class of drug currently used to prevent heartworm disease. Their extremely high potency in vivo is not mirrored by their activity against Dirofilaria immitis larvae in vitro, leading to suggestions that they may require host immune functions to kill the parasites. We have previously shown that ivermectin stimulates the binding of canine peripheral blood mononuclear cells (PBMCs) and polymorphonuclear leukocytes (PMNs) to D. immitis microfilariae (Mf). We have now extended these studies to moxidectin and examined the ability of both drugs to stimulate canine PBMC and PMN attachment to Mf from multiple strains of D. immitis, including two that are proven to be resistant to ivermectin in vivo. Both ivermectin and moxidectin significantly increased the percentage of drug-susceptible parasites with cells attached at very low concentrations (<10 nM), but much higher concentrations of ivermectin (>100 nM) were required to increase the percentage of the two resistant strains, Yazoo-2013 and Metairie-2014, with cells attached. Moxidectin increased the percentage of the two resistant strains with cells attached at lower concentrations (<10 nM) than did ivermectin. The attachment of the PBMCs and PMNs did not result in any parasite killing in vitro. These data support the biological relevance of the drug-stimulated attachment of canine leukocytes to D. immitis Mf and suggest that this phenomenon is related to the drug resistance status of the parasites.

Inflammatory adipocyte-derived extracellular vesicles promote leukocyte attachment to vascular endothelial cells

Background and aimsObesity is associated with an increased risk of cardiovascular disease, but the mechanisms involved are not completely understood. In obesity, the adipocyte microenvironment is characterised by both hypoxia and inflammation. Therefore, we sought to determine whether extracellular vesicles (EVs) derived from adipocytes in this setting might be involved in mediating cardiovascular disease, specifically by promoting leukocyte attachment to vascular endothelial cells. MethodsMature 3T3-L1 adipocytes were incubated for 24 h under control, TNF-α (30 ng/mL), hypoxia (1% O2), or TNF-α+hypoxia (30 ng/mL, 1% O2) conditions. EVs were isolated by differential ultracentrifugation and analysed by nanoparticle tracking analysis. Primary human umbilical vein endothelial cells (HUVECs) were treated with EVs for 6 h before being lysed for Western blotting to investigate changes in adhesion molecule production, or for use in leukocyte attachment assays. ResultsEVs from adipocytes treated with TNF-α and TNF-α+hypoxia increased vascular cell adhesion molecule (VCAM-1) production in HUVECs compared to basal level (4.2 ± 0.6 and 3.8 ± 0.3-fold increase, respectively (p < 0.05)), an effect that was inhibited by an anti-TNF-α neutralising antibody. Production of other adhesion molecules (E-selectin, P-selectin, platelet endothelial cell adhesion molecule and VE-Cadherin) was unchanged. Pre-incubating HUVECs with TNF-α+hypoxia EVs significantly increased leukocyte attachment compared to basal level (3.0 ± 0.4-fold increase (p < 0.05)). ConclusionsInflammatory adipocyte EVs induce VCAM-1 production in vascular endothelial cells, accompanied by enhanced leukocyte attachment. Preventing adipocyte derived EV-induced VCAM-1 upregulation may offer a novel therapeutic target in the prevention of obesity-driven cardiovascular disease.

JAK2-V617F promotes venous thrombosis through β1/β2 integrin activation.

JAK2-V617F-positive chronic myeloproliferative neoplasia (CMN) commonly displays dysfunction of integrins and adhesion molecules expressed on platelets, erythrocytes, and leukocytes. However, the mechanism by which the 2 major leukocyte integrin chains, β1 and β2, may contribute to CMN pathophysiology remained unclear. β1 (α4β1; VLA-4) and β2 (αLβ2; LFA-1) integrins are essential regulators for attachment of leukocytes to endothelial cells. We here showed enhanced adhesion of granulocytes from mice with JAK2-V617F knockin (JAK2+/VF mice) to vascular cell adhesion molecule 1- (VCAM1-) and intercellular adhesion molecule 1-coated (ICAM1-coated) surfaces. Soluble VCAM1 and ICAM1 ligand binding assays revealed increased affinity of β1 and β2 integrins for their respective ligands. For β1 integrins, this correlated with a structural change from the low- to the high-affinity conformation induced by JAK2-V617F. JAK2-V617F triggered constitutive activation of the integrin inside-out signaling molecule Rap1, resulting in translocation toward the cell membrane. Employing a venous thrombosis model, we demonstrated that neutralizing anti-VLA-4 and anti-β2 integrin antibodies suppress pathologic thrombosis as observed in JAK2+/VF mice. In addition, aberrant homing of JAK2+/VF leukocytes to the spleen was inhibited by neutralizing anti-β2 antibodies and by pharmacologic inhibition of Rap1. Thus, our findings identified cross-talk between JAK2-V617F and integrin activation promoting pathologic thrombosis and abnormal trafficking of leukocytes to the spleen.

Dual-Targeted Theranostic Delivery of miRs Arrests Abdominal Aortic Aneurysm Development.

Abdominal aortic aneurysm (AAA) is an often deadly disease without medical, non-invasive treatment options. The upregulation of vascular cell adhesion molecule-1 (VCAM-1) on aortic endothelium provides an early target epitope for a novel biotechnological theranostic approach. MicroRNA-126 was used as a therapeutic agent, based on its capability to downregulate VCAM-1 expression in endothelial cells and thereby reduces leukocyte adhesion and exerts anti-inflammatory effects. Ultrasound microbubbles were chosen as carriers, allowing both molecular imaging as well as targeted therapy of AAA. Microbubbles were coupled with a VCAM-1-targeted single-chain antibody (scFvmVCAM-1) and a microRNA-126 mimic (M126) constituting theranostic microbubbles (TargMB-M126). TargMB-M126 downregulates VCAM-1 expression in vitro and in an in vivo acute inflammatory murine model. Most importantly, using TargMB-M126 and ultrasound-guided burst delivery of M126, the development of AAA in an angiotensin-II-induced mouse model can be prevented. Overall, we describe a unique biotechnological theranostic approach with the potential for early diagnosis and long-sought-after medical therapy of AAA.

Omentin-1 ameliorates the attachment of the leukocyte THP-1 cells to HUVECs by targeting the transcriptional factor KLF2

Oxidation of low-density lipoproteins (ox-LDL) plays a critical role in endothelial dysfunction and the pathological progression of atherosclerosis by causing leukocyte attachment to endothelial surfaces. Omentin-1, an important adipokine primarily secreted by stromal vascular cells, has displayed various biological functions in diverse tissues. However, little information regarding the effects of omentin-1 on ox-LDL- induced endothelial dysfunction has been reported before. In the current study, we found that omentin-1 significantly reduced the attachment of the leukocyte THP-1 cells to human umbilical vein endothelial cells (HUVECs) in a dose dependent manner. Additionally, omentin-1 treatment prevented the expression of cell adhesion molecules such as VCAM-1 and E-selectin at both the mRNA level and the protein level. Notably, we found that omentin-1 significantly restored ox-LDL-induced reduction of KLF2, an important transcriptional factor and regulator of endothelial function. Also, omentin-1 promoted the expression of KLF2 target genes eNOS and PAI-1. Mechanistically, our results indicate that the effects of omentin-1 on KLF2 expression are mediated by p53. These results highlight the potential of omentin-1 in preventing endothelial dysfunction and atherosclerosis.

Cigarette Smoke Increases Endothelial CXCL16-Leukocyte CXCR6 Adhesion In Vitro and In Vivo. Potential Consequences in Chronic Obstructive Pulmonary Disease.

Cardiovascular disease (CVD) is a major comorbidity in chronic obstructive pulmonary disease (COPD). Although the mechanism of its development remains largely unknown, it appears to be associated with cigarette consumption and reduced lung function. Therefore, the aim of this study was to investigate the potential link between water-soluble cigarette smoke extract (CSE)-induced endothelial dysfunction and the function of CXCL16/CXCR6 axis on the initial attachment of leukocytes, in addition to its possible impact on COPD-associated systemic inflammation. To do this, we employed several experimental approaches, including RNA silencing and flow cytometry analysis, the dynamic flow chamber technique, and intravital microscopy in the cremasteric arterioles of animals exposed to cigarette smoke (CS). CSE-induced arterial CXCL16 expression, leading to increased platelet–leukocyte and mononuclear cell adhesiveness. CSE-induced CXCL16 expression was dependent on Nox5 expression and subsequent RhoA/p38 MAPK/NF-κB activation. Flow cytometry analysis revealed that COPD patients (n = 35) presented greater numbers of activated circulating platelets (PAC-1+ and P-selectin+) expressing CXCL16 and CXCR6 as compared with age-matched controls (n = 17), with a higher number of CXCR6+-platelets in the smoking COPD group than in ex-smokers. This correlated with enhanced circulating CXCR6+-platelet–leukocyte aggregates in COPD patients. The increase in circulating numbers of CXCR6-expressing platelets and mononuclear cells resulted in enhanced platelet–leukocyte and leukocyte adhesiveness to CSE-stimulated arterial endothelium, which was greater than that found in age-matched controls and was partly dependent on endothelial CXCL16 upregulation. Furthermore, CS exposure provoked CXCL16-dependent leukocyte–arteriolar adhesion in cremasteric arterioles, which was significantly reduced in animals with a nonfunctional CXCR6 receptor. In conclusion, we provide the first evidence that increased numbers of CXCR6-expressing circulating platelets and mononuclear leukocytes from patients with COPD might be a marker of systemic inflammation with potential consequences in CVD development. Accordingly, CXCL16/CXCR6 axis blockade might constitute a new therapeutic approach for decreasing the risk of CVD in COPD patients.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) Deficiency is Protective Against Venous Thrombosis in Mice

The effect of lipid lowering on the incidence of deep venous thrombosis (DVT) is controversial. The purpose of this study was to determine the effect of proprotein convertase subtilisin/kexin type 9 (PCSK9) deficiency on development of DVT in mice. Pcsk9 deficient (pcsk9−/−) and wild-type (WT) littermates underwent partial inferior vena cava (IVC) ligation to induce venous thrombosis. 48 hours following IVC ligation, IVC thrombosis was evident in 60% of WT mice and 25% of pcsk9−/− mice (p < 0.05). Analysis of IVC thrombosis revealed greater thrombus weight, length, myeloid cell recruitment, and more neutrophil extracellular trap formation (NETs) in WT compared to pcsk9−/− mice. Intravital microscopy performed two hours following partial IVC ligation revealed that leukocyte firm attachment was increased in WT mice compared to mice undergoing a sham operation, however leukocyte attachment was reduced in pcsk9−/− mice compared to WT mice. In conclusion, deficiency of PCSK9 is associated with protection from venous thrombosis. This protection is associated with reduced leukocyte recruitment and NET formation at the site of thrombosis.

Beneficial role of the phytoestrogen genistein on vascular calcification

Although soy phytoestrogen are proposed to prevent or improve postmenopausal vascular and bone diseases, the currently available data are controversial and unclear. In this study we evaluated the molecular and biochemical action of genistein on the cellular events involved in vascular calcification. Rat monocytes, aortic vascular cell and osteoblasts cultures in vitro exposed to Gen were employed. Gen down regulated the expression of cell adhesion molecules involved in stable leukocyte attachment. Using flow cytometry we found that the PE significantly diminished monocyte integrins CD11b, CD11c and CD18 expression either under basal and pro-inflammatory environment. At endothelial level, Gen also reduced Intercellular Adhesion Molecule 1 mRNA expression. On vascular muscle cells, the PE markedly reduced cell proliferation and migration. When vascular calcification was studied, muscle cells transdifferentiation into osteoblasts like cells was evaluated. Cells were cultured in osteogenic medium for 21 days. The expression of alkaline phosphatase and the presence of calcified nodules in the extracellular matrix were selected as features of muscle transdifferentiation. Calcified muscle cells exhibited higher levels of alkaline phosphatase activity and enhanced deposition of calcium nodules respect to native cells. Both osteoblastic markers were significantly reduced after Gen treatment. In contrast to this anti-osteogenic action, on bone cells Gen promoted osteoblasts growth, enhanced alkaline phosphatase activity and increased matrix mineralization. Its mitogenic action on osteoblasts directly depends on nitric oxide endothelial production stimulated by the PE. The data presented suppose a beneficial role of Gen on bone and vascular cells, with a cross link between both systems.

IRF-5 accelerates leukocyte adhesion to endothelial cells in ischemia-reperfusion injury through regulating the transcription of VCAM-1

Ischemia-reperfusion injury (IRI) has been implicated in many pathological conditions, including cardiovascular diseases. Adhesion of leukocytes to the surface of endothelial cells has been considered as one of the principle steps in the pathological cascade of inflammatory tissue damage during IRI. The role of the transcriptional factor interferon regulatory factor-5 (IRF-5) in endothelial physiology remains unknown. Here, we report that IRF-5 is expressed in human umbilical vein endothelial cells (HUVECs) and is rapidly upregulated in response to IRI, mediated by the JAK2/STAT3 pathway. Importantly, IRF-5 is involved in IRI-induced attachment of THP-1 leukocytes to HUVECs. Mechanistically, it was found that IRF-5 targeted the expression of vascular cell adhesion molecule 1 (VCAM-1) at the transcriptional level by binding to its promoter. In conclusion, we identify IRF-5 as a new regulator and thus a therapeutic target in IRI-driven cardiovascular pathologies.

Decreased sL-selectin serum levels in sleep apnea syndrome patients with cardiovascular diseases.

Obstructive sleep apnea syndrome (OSA) is a common disorder associated with an increased risk of cardiovascular diseases. sL-selectin is an adhesion molecule released from the surface of leukocytes as they are activated and may inhibit leukocyte attachment to the endothelium. The aim of this study was to evaluate sL-selectin serum levels in OSA patients with cardiovascular diseases. A total of 163 OSA patients were enrolled in the study. The mean age was 55.41 ± 8.63 years and the mean AHI (apnea hypopnea index) was 35.02 ± 22.28/h. A control group was composed of 59 healthy subjects. All subjects underwent a nocturnal respiratory polygraphy. sL-selectin serum levels were measured using the enzyme-linked immunosorbent assay (ELISA) method. sL-selectin serum levels were significantly lower in OSA patients than in the control group (1080.02 ± 175.29 vs 1350.73 ± 569.75 ng/mL, p < 0.05). In addition, there was a negative correlation between sL-selectin levels and AHI and DI and a positive correlation between sL-selectin levels and mean and minimum saturation. sL-selectin levels were lower in OSA patients with cardiovascular diseases than in those without co-morbidities. We also found that sL-selectin correlated positively with HDL-cholesterol (high density lipoprotein) and negatively with uric acid and CRP (C-reactive protein). Our work, together with observations relating to other diseases and experimental studies, suggests that lower sL-selectin levels could play a role in an increased risk of cardiovascular complications in sleep apnea syndrome. However future studies are needed to understand the role of sL-selectin in sleep apnea syndrome.

Endothelial CD99 supports arrest of mouse neutrophils in venules and binds to neutrophil PILRs

AbstractCD99 is a crucial regulator of the transmigration (diapedesis) of leukocytes through the blood vessel wall. Here, we report that CD99 acts at 2 different steps in the extravasation process. In agreement with previous antibody-blocking experiments, we found that CD99 gene inactivation caused neutrophil accumulation between venular endothelial cells and the basement membrane in the inflamed cremaster. Unexpectedly, we additionally found that leukocyte attachment to the luminal surface of the venular endothelium was impaired in the absence of CD99. Intravital video microscopy revealed that CD99 supported rapid chemokine-induced leukocyte arrest. Inhibition of leukocyte attachment and extravasation were both solely due to the absence of CD99 on endothelial cells, whereas CD99 on leukocytes was irrelevant. Therefore, we searched for heterophilic ligands of endothelial CD99 on neutrophils. We found that endothelial cells bind to the paired immunoglobulinlike receptors (PILRs) in a strictly CD99-dependent way. In addition, endothelial CD99 was coprecipitated with PILRs from neutrophils that adhered to endothelial cells. Furthermore, soluble CD99 carrying a transferable biotin tag could transfer this tag covalently to PILR when incubated with intact neutrophils. Binding of neutrophils under flow to a surface coated with P-selectin fragment crystallizable (Fc) and intercellular adhesion molecule 1 (ICAM-1) Fc became more shear resistant if CD99 Fc was coimmobilized. This increased shear resistance was lost if neutrophils were preincubated with anti-PILR antibodies. We concluded that endothelial CD99 promotes leukocyte attachment to endothelium in inflamed vessels by a heterophilic ligand. In addition, CD99 binds to PILRs on neutrophils, an interaction that leads to increased shear resistance of the neutrophil attachment to ICAM-1.