Platelet-monocyte Aggregates Research Articles

Circulating Factors and Ultrasono-findings are Linked to Previous Atherosclerotic Burden and Recurrent Risk.

: Background:In the progression of atherosclerosis, platelet activation and the interaction of platelets with leukocytes play a crucial role in arterial thrombus formation and are associated with the pathophysiology of carotid and cerebrovascular disease (CVD), including ischemic stroke. With aged participants, we evaluated and followed up the change in circulating factor and platelet-leukocyte aggregate levels in participants with or without CVD history. This study investigated whether circulating factor changes and ultrasonographic characteristics link to CVD risk and other relating long-term outcomes.Materials and Methods:Two hundred fifteen participants who enrolled in the study were divided into two groups with CVD and without CVD history. We evaluated and analyzed the correlation between ultrasonography-based morphological characteristics and circulating factor-based functional changes in both groups.Results:There was no difference in p-selectin level between both groups. However, activated monocyte and platelet-monocyte aggregate levels were higher in patients with previous CVD than without previous CVD. Circulating factor and ultrasonographical characteristics were correlated in the group with CVD, whereas these factors were not correlated in the group without CVD.Conclusion:We found that circulating blood factor levels showed a different tendency in participants with and without CVD history. The results depict that atherosclerotic severity might depend on the history of CVD and progression of atherosclerosis. We suggest that the circulating factor levels, atherosclerotic severity, and history of CVD are considered in the observation of pathologic progression to manage the development of CVD risks and CVD relating outcomes.

Platelet Transcriptomics Following Mechanical Unloading

Purpose End-stage heart failure (HF), including patients supported by left ventricular assist devices (LVAD), is associated with dysregulated thrombo-inflammatory responses which are mediated, in part, by platelets. While functional studies of platelet activation have been undertaken in HF patients, changes in the platelet transcriptome in LVAD patients have not previously been investigated. Methods We prospectively enrolled 32 patients receiving durable continuous flow LVADs and 20 donors without HF. We longitudinally measured platelet transcriptional changes by next-generation RNA-sequencing in patients prior to and following LVAD implantation. Results Patients were followed for a mean of 57 months post-LVAD implantation. Platelets were hyperactive in HF patients, pre-LVAD, as evidenced by significantly increased formation of circulating platelet-monocyte aggregates. Transcriptional profiling identified numerous genes (n=588) that were significantly (FDR angiogenesis , immune and inflammatory responses, apoptosis , and cardiac muscle contraction . The majority (80%) of genes in HF patients normalized by 90-days following LVAD implantation. There were 108 transcripts that remained altered and 50 transcripts that were newly differentially expressed at 90 days, all involved in the aforementioned pathways (Figure). Conclusion In this first report of longitudinal changes in platelet gene expression prior to and following LVAD support, we found that HF is associated with marked alterations in the platelet transcriptome. While mechanical circulatory support results in significant resolution in the majority of differentially expressed genes, a subset of the platelet transcriptome remains persistently activated. Further studies will delineate whether or not this latter group is involved with and potentially predictive of LVAD-related adverse events.

Human low‐affinity IgG receptor FcγRIIA polymorphism H131R associates with subclinical atherosclerosis and increased platelet activity in systemic lupus erythematosus

Essentials Systemic lupus erythematosus (SLE) patients are at increased risk for premature CVD. Platelet activity, vascular dysfunction and carotid artery plaque are associated with FcγRIIA genotype in SLE. FcγRIIA genotype was not associated with platelet activity or carotid plaque in healthy controls. FcγRIIA represents a link that connects platelet activity, vascular health and CVD in SLE. SUMMARY: Background Systemic lupus erythematosus (SLE) is a complex autoimmune disease associated with an elevated risk of premature cardiovascular disease. Platelets express receptors contributing to inflammation and immunity, including FcγRIIA, the low affinity receptor of the Fc portion of IgG antibodies. The variation at a single amino acid substitution, H131R, in the extracellular binding domain alters the affinity for IgG, which may account for individual variation in platelet activity and platelet-mediated disease. Objectives This study was performed to investigate the association between FcγRIIA genotype, preclinical atherosclerosis, platelet reactivity and vascular health. Methods FcγRIIA was genotyped in 80 SLE patients and 30 healthy controls. Carotid ultrasound plaque, soluble E-selectin and platelet aggregability were evaluated in SLE and matched controls. Results Carotid plaque was significantly more prevalent in SLE patients carrying a variant allele compared to those with a homozygous ancestral allele (58% vs. 25%, P=0.04). In contrast, prevalent carotid plaque was not associated with genotype in controls. Consistently, SLE variant FcγRIIA carriers vs. ancestral allele carriers had a significant increase in the levels of soluble E-selectin, which was not observed in controls. Monocyte and leukocyte-platelet aggregation and platelet aggregation in response to submaximal agonist stimulation were significantly elevated in SLE patients with the variant vs. ancestral genotype. Conclusions Carotid ultrasound plaque, soluble E-selectin levels and platelet activity were more frequently prevalent in SLE patients carrying variant FcγRIIA. The interplay between FcγRIIA-mediated platelet activation and endothelial cells might represent a mechanism underlying the pathogenesis of cardiovascular disease in SLE patients.

Differences in Monocyte Subsets and Monocyte-Platelet Aggregates in Acute Myocardial Infarction—PreliminaryResults

BackgroundMonocyte-platelet interaction may favor the development of a proatherogenic monocyte phenotype. It is still uncertain which of the 3 monocyte subpopulations interact with platelets to form monocyte-platelet aggregates (MPAs) in acute myocardial infarctions. The aim of our study was to evaluate the monocyte subsets, the percentage of MPAs and the involvement of monocyte subsets in MPA formation among patients with ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI), and compared to patients with stable angina (SA). MethodsMonocyte subsets and MPAs formation were measured in blood collected in 3.2% sodium citrate tubes by means of flow cytometry. ResultsClassical, intermediate and nonclassical monocyte percentages were statistically different when comparing patients with STEMI and NSTEMI. Moreover, classical and intermediate monocytes were statistically different when comparing the STEMI and SA group; however, only the classical monocyte subset was found to be higher in the acute myocardial infarction group compared to the SA group. The percentage of MPAs was significantly higher in STEMI (50.1%) compared to NSTEMI (22.9%). We found no differences in the involvement of monocyte subsets in MPA formation between patients with STEMI and NSTEMI and in comparison with the SA group. ConclusionsThese findings suggest that the increase in circulating levels of classical monocytes in patients with STEMI as compared to NSTEMI reflects the severity of the acute event. The increased percentage of MPAs may favor the development of STEMI compared to NSTEMI.

SYNTHESIS, CHARACTERIZATION, AND IN VIVO IMMUNOMODULATION OF CCR2 AND VASCULAR ENDOTHELIAL GROWTH FACTOR ANTAGONISTS-LOADED PEGYLATED NANOPARTICLES

Objective: Chemokine (C-C motif) ligand 2 (CCL2), a candidate of cytokines, orchestrates immune cell recruitment to inflamed organs. CCL2 has been shown to have direct angiogenic effects, so providing an anti-angiogenic agent, Avastin (AV), to be combined with the CCR2 antagonist (concentration ratio [CR]) plays an essential role in the hemostatic strategy for immunomodulation. Lack of targetability and the adverse effects of chemical treatments are the main obstacles led scientists to develop novel strategies using nano-delivery approaches such as pegylated nanoparticles (NPs) which exhibits reduced drug clearance rates. The rationale of the current study is to test the in vivo immunomodulatory effects of AV and/or CR in their NPs or free counterparts.Methods: These NPs were synthesized and characterized using different physicochemical techniques. Males Wistar rats (n=114) were used and divided into 7 groups treated with vehicle, AV, AVNP, CCR2 antagonist (CR), CCR2 antagonist NPs (CRNP), AV-CCR2 antagonist (AVCR), and AV-CCR2 antagonist NPs (AVCRNP). Groups were subdivided into three subgroups according to the administrated dose. Blood was taken from rats for differential leukocyte and platelet profile measurements. Sera were collected to test vascular endothelial growth factor (VEGF) levels. Autopsy samples from liver were taken for histopathological investigation.Results: The morphology of the NPs was spherical and had sizes ranging from 89.89 nm to 146 nm. Monocytes and lymphocytes accumulated in the blood circulation and VEGF levels were inhibited after AV and CR administrations. In addition, large platelets concentration ratio was elevated in the blood circulation.Conclusion: We concluded that AV ad CR therapeutic regimens have an immunomodulatory role through induction of monocyte-platelet aggregation and inhibition of VEGF.

SYNTHESIS, CHARACTERIZATION, AND IN VIVO IMMUNOMODULATION OF CCR2 AND VASCULAR ENDOTHELIAL GROWTH FACTOR ANTAGONISTS-LOADED PEGYLATED NANOPARTICLES

Objective: Chemokine (C-C motif) ligand 2 (CCL2), a candidate of cytokines, orchestrates immune cell recruitment to inflamed organs. CCL2 has been shown to have direct angiogenic effects, so providing an anti-angiogenic agent, Avastin (AV), to be combined with the CCR2 antagonist (concentration ratio [CR]) plays an essential role in the hemostatic strategy for immunomodulation. Lack of targetability and the adverse effects of chemical treatments are the main obstacles led scientists to develop novel strategies using nano-delivery approaches such as pegylated nanoparticles (NPs) which exhibits reduced drug clearance rates. The rationale of the current study is to test the in vivo immunomodulatory effects of AV and/or CR in their NPs or free counterparts.Methods: These NPs were synthesized and characterized using different physicochemical techniques. Males Wistar rats (n=114) were used and divided into 7 groups treated with vehicle, AV, AVNP, CCR2 antagonist (CR), CCR2 antagonist NPs (CRNP), AV-CCR2 antagonist (AVCR), and AV-CCR2 antagonist NPs (AVCRNP). Groups were subdivided into three subgroups according to the administrated dose. Blood was taken from rats for differential leukocyte and platelet profile measurements. Sera were collected to test vascular endothelial growth factor (VEGF) levels. Autopsy samples from liver were taken for histopathological investigation.Results: The morphology of the NPs was spherical and had sizes ranging from 89.89 nm to 146 nm. Monocytes and lymphocytes accumulated in the blood circulation and VEGF levels were inhibited after AV and CR administrations. In addition, large platelets concentration ratio was elevated in the blood circulation.Conclusion: We concluded that AV ad CR therapeutic regimens have an immunomodulatory role through induction of monocyte-platelet aggregation and inhibition of VEGF.

Circulating monocyte-platelet aggregates are a robust marker of platelet activity in cardiovascular disease

Background and aimsPlatelets are a major culprit in the pathogenesis of cardiovascular disease (CVD). Circulating monocyte-platelet aggregates (MPA) represent the crossroads between atherothrombosis and inflammation. However, there is little understanding of the platelets and monocytes that comprise MPA and the prevalence of MPA in different CVD phenotypes. We aimed to establish (1) the reproducibility of MPA over time in circulating blood samples from healthy controls, (2) the effect of aspirin, (3) the relationship between MPA and platelet activity and monocyte subtype, and (4) the association between MPA and CVD phenotype (coronary artery disease, peripheral artery disease [PAD], abdominal aortic aneurysm, and carotid artery stenosis). Methods and resultsMPA were identified by CD14+ monocytes positive for CD61+ platelets in healthy subjects and in patients with CVD. We found that MPA did not significantly differ over time in healthy controls, nor altered by aspirin use. Compared with healthy controls, MPA were significantly higher in CVD (9.4% [8.2, 11.1] vs. 21.8% [11.5, 44.1], p < 0.001) which remained significant after multivariable adjustment (β = 9.1 [SER = 3.9], p = 0.02). We found PAD to be associated with a higher MPA in circulation (β = 19.3 [SER = 6.0], p = 0.001), and among PAD subjects, MPA was higher in subjects with critical limb ischemia (34.9% [21.9, 51.15] vs. 21.6% [15.1, 40.6], p = 0.0015), and significance remained following multivariable adjustment (β = 14.77 (SE = 4.35), p = 0.001). ConclusionsCirculating MPA are a robust marker of platelet activity and monocyte inflammation, unaffected by low-dose aspirin, and are significantly elevated in subjects with CVD, particularly those with PAD.

Tissue factor expression on platelets in patients with acute coronary syndrome

Objective To investigate the expression of tissue factor (TF) on platelet monocyte aggregates (PMA) and platelets as a participating factor in pathogenesis of acute coronary syndrome (ACS). Background ACS is due to rupture of an arterial plaque. TF on platelets and PMA may provide potential distal sites for generation of new thrombi. In this study, the expressions of TF on PMA and platelets are investigated as participating factors in pathogenesis of ACS. Patients and methods Twenty-five patients with acute myocardial infarction, 25 patients with stable angina, and 20 clinically healthy patients as control are investigated for TF on PMA, as well as platelet-associated TF by flow cytometry analysis. Results TF on platelets and PMA were highly significant in patients with acute myocardial infarction than those with stable angina and controls. Conclusion The greater expression of TF on platelets and PMA strengthens the link between platelet activation, blood coagulation, and thrombus formation and may further contribute to the hypercoagulability associated with the disease.

Multiplexed Label-Free Fractionation of Peripheral Blood Mononuclear Cells for Identification of Monocyte-Platelet Aggregates.

Monocytes and platelets play key roles in atherosclerosis and thrombosis, and circulating monocyte-platelet aggregates (MPA) in blood have been widely proposed as surrogate biomarkers for cardiovascular risk stratification and monitoring antiplatelet therapies. However, conventional MPA characterization is based on whole-blood fixation and flow cytometry analysis which adversely affect cell viability and detection accuracy due to significant leukocyte and platelet contaminations. Herein, we introduce a rapid and label-free microfluidic approach for complete size-based fractionation of peripheral blood mononuclear cells (PBMCs) into monocytes, lymphocytes, and platelets. The developed biochip enables gentle sorting of intact MPA in the enriched monocytes with efficient depletion of lymphocytes and platelets for accurate MPA quantification. We first compared the developed microfluidic technology (dean flow fractionation, DFF) with standard magnetic negative isolation (MACS) and observed that DFF-sorted monocytes had similar viability, purity, and key immune functions (phagocytosis, macrophage differentiation) as MACS-sorted monocytes. As proof of concept for diabetes testing, we isolated and characterized monocytes/MPA from a cohort of healthy ( n = 5) and type 2 diabetes mellitus (T2DM) subjects ( n = 8) in PBMCs and DFF-sorted monocytes. High-speed imaging, immunofluorescence, and flow cytometry analysis clearly indicated higher levels of MPA in T2DM patients ( P < 0.05) with enhanced MPA detection sensitivity in DFF-sorted monocytes ( P < 0.05). Taken together, the developed DFF technology greatly facilitates high-throughput (∼130 μL min-1) label-free isolation of monocyte/MPA from PBMCs and can be further developed into a clinical tool for point-of-care cardiovascular risk stratification in metabolic disorders including T2DM.

Short- and long-term effects of hemodialysis on platelet and monocyte activity markers of atherosclerosis in patients with end-stage renal disease.

In hemodialysis (HD) patients cardiovascular events represent the predominant cause of mortality. Since platelet and monocyte activity markers play an important role in cardiovascular mortality, this study assessed the influence of HD on these markers. Forty one HD patients (25 male, 16 female) were included. Blood samples were obtained before and after a single HD session at baseline and again after an elapsed period of 114 ± 21 days (91-175 days) on maintenance hemodialysis. Surface expression of CD40L and CD62P on platelets, tissue factor binding on monocytes and platelet-monocyte aggregates were measured by flow cytometry. Plasma levels of monocyte chemotactic protein-1 (MCP-1), interleukin-6 (IL-6), tumor necrosis factor alpha (TNFa) and soluble CD40L were analyzed by enzyme linked immunosorbent assay. Tissue factor on monocytes was significantly increased after a single HD session at baseline (p = 0.041), whereas platelet-monocyte aggregates, the expression of CD40L and CD62P on platelets did not change significantly. After a mean of 114 ± 21 days of HD therapy, tissue factor on monocytes (p < 0.0001), platelet-monocytes aggregates (p < 0.0001), plasma levels of MCP-1 (p = 0.012) and TNFa (p = 0.046) were significantly decreased compared to baseline values. In contrast, platelet surface expression of CD40L and CD62P as well as plasma levels of sCD40L and IL-6 were not attenuated significantly. There was no significant correlation detected between the markers examined and the cumulative time on hemodialysis. Platelet and monocyte activity markers assessed in this study do not appear to be significantly increased by HD therapy. Therefore, these markers probably cannot be accountable for increased cardiovascular mortality in chronic HD patients.

Exosite 1 thrombin inhibition with JNJ-64179375 inhibits thrombus formation in a human translational model of thrombosis.

AimsJNJ-64179375 (hereafter JNJ-9375) is a first-in-class, highly specific, large molecule, exosite 1 thrombin inhibitor. In preclinical studies, JNJ-9375 demonstrated robust antithrombotic protection with a wider therapeutic index when compared to apixaban. The purpose of the present study was to examine for the first time the antiplatelet, anticoagulant and antithrombotic effects of JNJ-9375 in a translational model of ex vivo human thrombosis.Methods and resultsFifteen healthy volunteers participated in a double-blind randomized crossover study of JNJ-9375 (2.5, 25, and 250 μg/mL), bivalirudin (6 μg/mL; positive control), and matched placebo. Coagulation, platelet activation, and thrombus formation were determined using coagulation assays, flow cytometry, and an ex vivo perfusion chamber, respectively.JNJ-9375 caused concentration-dependent prolongation of all measures of blood coagulation (prothrombin time, activated partial thromboplastin time, and thrombin time; P < 0.001 for all) and agonist selective inhibition of thrombin (0.1 U/mL) stimulated platelet p-selectin expression (P < 0.001) and platelet-monocyte aggregates (P = 0.002). Compared to placebo, JNJ-9375 (250 μg/mL) reduced mean total thrombus area by 41.1% (95% confidence intervals 22.3 to 55.3%; P < 0.001) at low shear and 32.3% (4.9 to 51.8%; P = 0.025) at high shear. Under both shear conditions, there was a dose-dependent decrease in fibrin-rich thrombus (P < 0.001 for both) but not platelet-rich thrombus (P = ns for both).ConclusionExosite 1 inhibition with JNJ-9375 caused prolongation of blood coagulation, selective inhibition of thrombin-mediated platelet activation, and reductions in ex vivo thrombosis driven by a decrease in fibrin-rich thrombus formation. JNJ-9375 represents a novel class of anticoagulant with potential therapeutic applications.

Papain Ameliorates the MPAs Formation-Mediated Activation of Monocytes by Inhibiting Cox-2 Expression via Regulating the MAPKs and PI3K/Akt Signal Pathway.

Monocytes activation and subsequent inflammatory response mediated by monocyte-platelet aggregates (MPAs) formation play the key roles in the early pathogenesis of atherosclerosis (AS). Exploration of novel drugs to ameliorate MPAs formation-mediated monocytes activation would be helpful for the treatment of AS patients. Papain has definite pharmacological effects including antiplatelet, thrombolysis, and anti-inflammation. However, its effect on MPAs formation and the following monocytes activation remains vague. This study aimed to illustrate the underlying mechanisms of papain on MPAs formation-initiated monocytes activation in vitro. In this study, Papain, Cox-2 inhibitor (NS-398), and NF-κB agonist (TNF-α) were used as the treating agents, respectively. MPAs formation and activated monocytes were measured by flow cytometry (FCM). Cox-2 mRNA, MCP-1, and proteins of Cox-2 and NF-κB signal pathway were detected by qRT-PCR, ELISA, and western blotting, respectively. As we observed, papain exhibited the powerful inhibitory effects on thrombin-mediated MPAs formation and monocytes activation in a concentration-dependent manner as what Cox-2 inhibitor demonstrated. However, the inhibitory tendency was significantly reversed by TNF-α. We also discovered that both Cox-2 mRNA and protein expression as well as the release of MCP-1 of monocyte was inhibited by either papain or NS-398, but TNF-α stimulated Cox-2 expression and release of MCP-1. The results of western blotting assay indicated that thrombin-mediated proteins expression of MAPKs and PI3K/Akt signal pathway was inhibited by papain and NS-398. However, TNF-α notably abated the inhibitory effects of papain on the process of MPAs-initiated monocytes activation. Our findings suggest that papain can inhibit the MPAs formation-mediated activation of monocytes by inhibiting the MAPKs and PI3K/Akt signal pathway.

Platelet activation and prothrombotic properties in a mouse model of peritoneal sepsis

Sepsis is associated with thrombocytopenia and microvascular thrombosis. Studies have described platelets implication in this pathology but their kinetics of activation and behavior remain poorly known. We show in a mouse model of peritonitis, the appearance of platelet-rich thrombi in organ microvessels and organ damage. Complementary methods are necessary to characterize platelet activation during sepsis as circulating soluble markers and platelet-monocyte aggregates revealed early platelet activation, while surface activation markers were detected at later stage. A microfluidic based ex-vivo thrombosis assay demonstrated that platelets from septic mice have a prothrombotic behavior at shear rate encountered in microvessels. Interestingly, we found that even though phosphoinositide-3-kinase β−deficient platelet mice formed less thrombi in liver microcirculation, peritoneal sepsis activates a platelet alternative pathway to compensate the otherwise mandatory role of this lipid-kinase to form stable thrombi at high shear rate. Platelets are rapidly activated during sepsis. Thrombocytopenia can be attributed in part to platelet-rich thrombi formation in capillaries and platelet-leukocytes interactions. Platelets from septic mice have a prothrombotic phenotype at a shear rate encountered in arterioles. Further studies are necessary to unravel molecular mechanisms leading to this prothrombotic state of platelets in order to guide the development of future treatments of polymicrobial sepsis.

P3786The role of rho kinases in thrombin-stimulated platelets and monocyte platelet aggregates in atherothrombosis

P3786The role of rho kinases in thrombin-stimulated platelets and monocyte platelet aggregates in atherothrombosis

Early Intravascular Events Are Associated with Development of Acute Respiratory Distress Syndrome. A Substudy of the LIPS-A Clinical Trial.

Acute respiratory distress syndrome (ARDS) is a devastating illness with limited therapeutic options. A better understanding of early biochemical and immunological events in ARDS could inform the development of new preventive and treatment strategies. To determine select peripheral blood lipid mediator and leukocyte responses in patients at risk for ARDS. Patients at risk for ARDS were randomized as part of a multicenter, double-blind clinical trial of aspirin versus placebo (the LIPS-A [Lung Injury Prevention Study with Aspirin] trial; NCT01504867). Plasma thromboxane B2 (TXB2), aspirin-triggered lipoxin A4 (15-epi-LXA4, ATL), and peripheral blood leukocyte number and activation were determined on enrollment and after treatment with either aspirin or placebo. Thirty-three of 367 subjects (9.0%) developed ARDS after randomization. Baseline ATL levels, total monocyte counts, intermediate monocyte counts, and monocyte-platelet aggregates were associated with the development of ARDS. Peripheral blood neutrophil count and monocyte-platelet aggregates significantly decreased over time. Of note, nine subjects developed ARDS after randomization yet before study drug initiation, including seven subjects assigned to aspirin treatment. Subjects without ARDS at the time of first dose demonstrated a lower incidence of ARDS with aspirin treatment. Compared with placebo, aspirin significantly decreased TXB2 and increased the ATL/TXB2 ratio. Biomarkers of intravascular monocyte activation in at-risk patients were associated with development of ARDS. The potential clinical benefit of early aspirin for prevention of ARDS remains uncertain. Together, results of the biochemical and immunological analyses provide a window into the early pathogenesis of human ARDS and represent potential vascular biomarkers of ARDS risk. Clinical trial registered with www.clinicaltrials.gov (NCT01504867).

Engulfment of Hb-activated platelets differentiates monocytes into pro-inflammatory macrophages in PNH patients.

The distinct response shown by different phenotypes of macrophages and monocytes under various clinical conditions has put the heterogeneity of these cells into focus of investigation for several diseases. Recently, we have described that after engulfing hemoglobin (Hb)-activated platelets, classical monocytes differentiated into pro-inflammatory phenotypes, which were abundant in the circulation of paroxysmal nocturnal hemoglobinuria (PNH) and sickle cell disease patients. Our current study shows that upon engulfment of Hb-activated platelets, monocytes differentiate into M1-macrophages under M1-polarization stimulus (GM-CSF, IFN-γ + LPS). When grown under M2-polarization stimulus (M-CSF, IL-4 + IL13), the cells exhibited an M1-like phenotype, secreted elevated levels of pro-inflammatory cytokines including TNF-α and IL-1β, and displayed loss of the secretion of cytokine such as IL-10 and also phagocytic ability unlike the conventional M2 macrophages. Interestingly, when differentiated under the above polarization stimulus, monocytes from PNH patients expressed high levels of CD80 and phospho-STAT1, like M1 macrophages. Hemolytic mice also exhibited a gradual increase in monocyte-platelet aggregates in circulation and accumulation of CD80high macrophages in thioglycollate-induced inflamed peritoneum. The spleen of the mice was also populated by CD80high macrophages with compromised phagocytic capacity. Our findings suggest that the hemolytic environment and specifically the Hb-activated platelets, which are abundant in circulation during intravascular hemolysis, closely regulate monocyte differentiation.

Abstract 150: Monocyte-Platelet Aggregates Correlate With the Prevalence and Severity of Aortic Aneurysms

Objective: To determine whether monocyte-platelet aggregates (MPA) correlate with aortic aneurysm (AA) prevalence and severity. BACKGROUND: Inflammation and intraluminal thrombus are key hallmarks of complex AA. While monocytes fuel inflammation in AA, the contribution of platelets is unknown. We hypothesized that increased platelet activity yields to MPA that drive AA development and indicate disease severity. Methods: Blood was collected from 49 symptomatic patients admitted for aneurysm repair procedures (8 thoracic and 41 abdominal) and 36 matched controls. All subjects were on aspirin monotherapy. Platelet responsiveness to agonists was characterized by light transmission aggregometry. Flow cytometry analysis allowed leukocytes (CD45+)/monocytes (CD14+)-platelet (CD61+) aggregates (LPA/MPA) measurements in the blood and profiled MPA in post-surgical aneurysm tissues. Results: Platelet aggregation in response to ADP (57% vs. 35% aggregation, p&lt;0.001) and arachidonic acid (24% vs. 16% aggregation, p=0.03), was increased in patients with AA versus controls. LPA (17.7 vs 6.2% CD61+ leukocytes, p=0.002) and MPA (18.0 vs 7.2% CD61+ Monocytes, p=0.008) were robustly increased in AA vs controls. MPA but not LPA was strongly and positively associated with AA size (p&lt;0.0001). To delve into the role of MPA in situ in AA sac, platelets and tissue macrophage activation was characterized. Compared to the non-diseased part of the aorta, diseased section had significantly higher platelet infiltration (7.0% vs 1.2% CD61+ cells, p=0.006) and interaction with CD68+ tissue macrophages (8.3% vs. 0.7%, CD61+ macrophages p=0.03). Notably, macrophages highly expressed the adhesion protein, ICAM-1, in the diseased part (39.6 vs 3.3% in the non-diseased section, p&lt;0.001) which further increased to 69.4% (p=0.01) when macrophages were in contact with platelets. Conclusions: Our data highlights MPA as a novel mediator valuable to predict AA prevalence and severity.

Extracellular Matrix Metalloproteinase Inducer EMMPRIN (CD147) in Cardiovascular Disease

The receptor EMMPRIN is involved in the development and progression of cardiovascular diseases and in the pathogenesis of myocardial infarction. There are several binding partners of EMMPRIN mediating the effects of EMMPRIN in cardiovascular diseases. EMMPRIN interaction with most binding partners leads to disease progression by mediating cytokine or chemokine release, the activation of platelets and monocytes, as well as the formation of monocyte-platelet aggregates (MPAs). EMMPRIN is also involved in atherosclerosis by mediating the infiltration of pro-inflammatory cells. There is also evidence that EMMPRIN controls energy metabolism of cells and that EMMPRIN binding partners modulate intracellular glycosylation and trafficking of EMMPRIN towards the cell membrane. In this review, we systematically discuss these multifaceted roles of EMMPRIN and its interaction partners, such as Cyclophilins, in cardiovascular disease.

Platelet-Derived MRP-14 Induces Monocyte Activation in Patients With Symptomatic Peripheral Artery Disease

BackgroundPeripheral artery disease (PAD), a diffuse manifestation of atherothrombosis, is a major cardiovascular threat. Although platelets are primary mediators of atherothrombosis, their role in the pathogenesis of PAD remains unclear. ObjectivesThe authors sought to investigate the role of platelets in a cohort of symptomatic PAD. MethodsThe authors profiled platelet activity, mRNA, and effector roles in patients with symptomatic PAD and in healthy controls. Patients with PAD and carotid artery stenosis were recruited into ongoing studies (NCT02106429 and NCT01897103) investigating platelet activity, platelet RNA, and cardiovascular disease. ResultsPlatelet RNA sequence profiling mapped a robust up-regulation of myeloid-related protein (MRP)-14 mRNA, a potent calcium binding protein heterodimer, in PAD. Circulating activated platelets were enriched with MRP-14 protein, which augmented the expression of the adhesion mediator, P-selectin, thereby promoting monocyte–platelet aggregates. Electron microscopy confirmed the firm interaction of platelets with monocytes in vitro and colocalization of macrophages with MRP-14 confirmed their cross talk in atherosclerotic manifestations of PAD in vivo. Platelet-derived MRP-14 was channeled to monocytes, thereby fueling their expression of key PAD lesional hallmarks and increasing their directed locomotion, which were both suppressed in the presence of antibody-mediated blockade. Circulating MRP-14 was heightened in the setting of PAD, significantly correlated with PAD severity, and was associated with incident limb events. ConclusionsThe authors identified a heightened platelet activity profile and unraveled a novel immunomodulatory effector role of platelet-derived MRP-14 in reprograming monocyte activation in symptomatic PAD. (Platelet Activity in Vascular Surgery and Cardiovascular Events [PACE]; NCT02106429; and Platelet Activity in Vascular Surgery for Thrombosis and Bleeding [PIVOTAL]; NCT01897103)

Elipsis: A Longitudinal Study of Electronic Patient-Reported Outcomes, Actigraphy and Biomarkers to Identify and Assess at-Home Vaso-Occlusive Crises in Adults and Adolescents with Sickle Cell Disease

Elipsis: A Longitudinal Study of Electronic Patient-Reported Outcomes, Actigraphy and Biomarkers to Identify and Assess at-Home Vaso-Occlusive Crises in Adults and Adolescents with Sickle Cell Disease