Soluble P-selectin in human plasma: effect of anticoagulant matrix and its levels in patients with cardiovascular disorders

Proteomic profiling for biomarker discovery in heparin-induced thrombocytopenia

ABSTRACT

New analytical techniques can assess hundreds of proteins simultaneously with high sensitivity, facilitating the observation of their complex interplay and role in disease mechanisms. We hypothesized that proteomic profiling targeting proteins involved in thrombus formation, inflammation, and the immune response would identify potentially new biomarkers for heparin-induced thrombocytopenia (HIT). Four existing panels of the Olink proximity extension assay covering 356 proteins involved in thrombus formation, inflammation, and immune response were applied to randomly selected patients with suspected HIT (confirmed HIT, n = 32; HIT ruled out, n = 38; and positive heparin/platelet factor 4 [H/PF4] antibodies, n = 28). The relative difference in protein concentration was analyzed using a linear regression model adjusted for sex and age. To confirm the test results, soluble P-selectin was determined using enzyme-linked immunosorbent assay (ELISA) in above mentioned patients and an additional second data set (n = 49). HIT was defined as a positive heparin-induced platelet activation assay (washed platelet assay). Among 98 patients of the primary data set, the median 4Ts score was 5 in patients with HIT, 4 in patients with positive H/PF4 antibodies, and 3 in patients without HIT. The median optical density of a polyspecific H/PF4 ELISA were 3.0, 0.9, and 0.3. Soluble P-selectin remained statistically significant after multiple test adjustments. The area under the receiver operating characteristic curve was 0.81 for Olink and 0.8 for ELISA. Future studies shall assess the diagnostic and prognostic value of soluble P-selectin in the management of HIT.

What can the plasma proteome tell us about platelets and (vice versa)?

Multi-omics approaches are being used increasingly to study physiological and pathophysiologic processes. Proteomics specifically focuses on the study of proteins as functional elements and key contributors to, and markers of the phenotype, as well as targets for diagnostic and therapeutic approaches. Depending on the condition, the plasma proteome can mirror the platelet proteome, and hence play an important role in elucidating both physiologic and pathologic processes. In fact, both plasma and platelet protein signatures have been shown to be important in the setting of thrombosis-prone disease states such as atherosclerosis and cancer. Plasma and platelet proteomes are increasingly being studied as a part of a single entity, as is the case with patient-centric sample collection approaches such as capillary blood. Future studies should cut across the plasma and platelet proteome silos, taking advantage of the vast knowledge available when they are considered as part of the same studies, rather than studied as distinct entities.

T cell activation is insufficient to drive SIV disease progression

Resolution of T cell activation and inflammation is a key determinant of the lack of SIV disease progression in African green monkeys (AGMs). Although frequently considered together, T cell activation occurs in response to viral stimulation of acquired immunity, while inflammation reflects innate immune responses to mucosal injury. We dissociated T cell activation from inflammation through regulatory T cell (Treg) depletion with Ontak (interleukin-2 coupled with diphtheria toxin) during early SIV infection of AGMs. This intervention abolished control of T cell immune activation beyond the transition from acute to chronic infection. Ontak had no effect on gut barrier integrity, microbial translocation, inflammation, and hypercoagulation, despite increasing T cell activation. Ontak administration increased macrophage counts yet decreased their activation. Persistent T cell activation influenced SIV pathogenesis, shifting the ramp-up in viral replication to earlier time points, prolonging the high levels of replication, and delaying CD4+ T cell restoration yet without any clinical or biological sign of disease progression in Treg-depleted AGMs. Thus, by inducing T cell activation without damaging mucosal barrier integrity, we showed that systemic T cell activation per se is not sufficient to drive disease progression, which suggests that control of systemic inflammation (likely through maintenance of gut integrity) is the key determinant of lack of disease progression in natural hosts of SIVs.

Plasma exosome proteomics reveals the pathogenesis mechanism of post-stroke cognitive impairment

Exploration and utilization of exosome biomarkers and their related functions provide the possibility for the diagnosis and treatment of post-stroke cognitive impairment (PSCI). To identify the new diagnostic and prognostic biomarkers of plasma exosome were uzed label-free quantitative proteomics and biological information analysis in PSCI patients. Behavioral assessments were performed, including the Mini-Mental Status Examination (MMSE), the Montreal Cognitive Assessment (MoCA), the Barthel index, the Morse Fall Seale (MFS) between control group (n = 10) and PSCI group (n = 10). The blood samples were collected to analyse the biomarker and differentially expressed proteins of plasma exosome using label-free quantitative proteomics and biological information. The exosomes marker proteins were determined by Western blot. The exosome morphology was observed by transmission electron microscopy. The scores of MMSE and MoCA were significantly decreased in the PSCI group. The PT% and high-density lipoprotein decreased and the INR ratio increased in PSCI group. The mean size of exosome was approximately 71.6 nm and the concentration was approximately 6.8E+7 particles/mL. Exosome proteomics identified 259 differentially expressed proteins. The mechanisms of cognitive impairment are related to regulate the degradation of ubiquitinated proteins, calcium dependent protein binding, cell adhesive protein binding, formation of fibrin clot, lipid metabolism and ATP-dependent degradation of ubiquitinated proteins in plasma exosome of PSCI patients. Plasma levels of YWHAZ and BAIAP2 were significantly increased while that of IGHD, ABCB6 and HSPD1 were significantly decreased in PSCI patients. These proteins might be target-related proteins and provide global insights into pathogenesis mechanisms of PSCI at plasma exosome proteins level.

Ischemic stroke with cancer: Hematologic and embolic biomarkers and clinical outcomes

BACKGROUND

Patients with cancer and acute ischemic stroke (AIS) face high rates of recurrent thromboembolism or death.

OBJECTIVES

To examine whether hematologic and embolic biomarkers soon after AIS are associated with subsequent adverse clinical outcomes.

METHODS

We prospectively enrolled 50 adults with active solid tumor cancer and AIS at two hospitals from 2016 to 2020. Blood was collected 72-120 h after stroke onset. A 30-min transcranial Doppler (TCD) microemboli detection study was performed. The exposure variables were hematologic markers of coagulation (D-dimer, thrombin-antithrombin), platelet (P-selectin), and endothelial activation (thrombomodulin, soluble intercellular adhesion molecule-1 [sICAM-1], soluble vascular cell adhesion molecule-1 [sVCAM-1]), and the presence of TCD microemboli. The primary outcome was a composite of recurrent arterial/venous thromboembolism or death. We used Cox regression to evaluate associations between biomarkers and subsequent outcomes.

RESULTS

During an estimated median follow-up time of 48 days (IQR, 18-312), 43 (86%) participants developed recurrent thromboembolism or death, including 28 (56%) with recurrent thromboembolism, of which 13 were recurrent AIS (26%). In unadjusted analysis, D-dimer (HR 1.6; 95% CI 1.2-2.0), P-selectin (HR 1.9; 95% CI 1.4-2.7), sICAM-1 (HR 2.2; 95% CI 1.6-3.1), sVCAM-1 (HR 1.6; 95% CI 1.2-2.1), and microemboli (HR 2.2; 95% CI 1.1-4.5) were associated with the primary outcome, whereas thrombin-antithrombin and thrombomodulin were not. D-dimer was the only marker associated with recurrent AIS (HR 1.2; 95% CI 1.0-1.5). Results were generally consistent in analyses adjusted for important prognostic variables.

CONCLUSIONS

Markers of hypercoagulability and embolic disease may be associated with adverse clinical outcomes in cancer-related stroke.

Chronic Immune Platelet Activation Is Followed by Platelet Refractoriness and Impaired Contractility

Autoimmune diseases, including systemic lupus erythematosus (SLE), have a high risk of thrombotic and hemorrhagic complications associated with altered platelet functionality. We studied platelets from the blood of SLE patients and their reactivity. The surface expression of phosphatidylserine, P-selectin, and active integrin αIIbβ3 were measured using flow cytometry before and after platelet stimulation. Soluble P-selectin was measured in plasma. The kinetics of platelet-driven clot contraction was studied, as well as scanning and transmission electron microscopy of unstimulated platelets. Elevated levels of membrane-associated phosphatidylserine and platelet-attached and soluble P-selectin correlated directly with the titers of IgG, anti-dsDNA-antibodies, and circulating immune complexes. Morphologically, platelets in SLE lost their resting discoid shape, formed membrane protrusions and aggregates, and had a rough plasma membrane. The signs of platelet activation were associated paradoxically with reduced reactivity to a physiological stimulus and impaired contractility that revealed platelet exhaustion and refractoriness. Platelet activation has multiple pro-coagulant effects, and the inability to fully contract (retract) blood clots can be either a hemorrhagic or pro-thrombotic mechanism related to altered clot permeability, sensitivity of clots to fibrinolysis, obstructiveness, and embologenicity. Therefore, chronic immune platelet activation followed by secondary platelet dysfunction comprise an understudied pathogenic mechanism that supports hemostatic disorders in autoimmune diseases, such as SLE.

Dependence of Electric Pulse Mediated Growth Factor Release on the Platelet Rich Plasma Separation Method

Platelet rich plasma (PRP) has been explored for multiple clinical applications, including dentistry, orthopedics, sports medicine, diabetic foot ulcers, and cosmetic treatments. Topical applications of PRP typically use thrombin to induce platelet activation, which is accompanied by growth factor release and clotting of the PRP, prior to treatment. Injectable PRP treatments typically use non-activated PRP under the assumption that collagen at the site of the injury mediates platelet activation to ensure growth factor release in vivo. Ex-vivo electrical stimulation of platelets is emerging as a robust, easy to use, instrument-based PRP activation technique to facilitate growth factor release with or without clotting, while providing tunability of growth factor release, clot mechanical properties (when desired), and serotonin release from the dense granules. This paper briefly reviews the key results of the electrical activation of platelets and demonstrates successful growth factor release by electrical ex-vivo stimulation without clotting for three types of PRP separated from whole blood using available commercial kits: Harvest, EmCyte and Eclipse. While these three types of PRP feature a wide range of platelet and red blood cell content compared to whole blood, we demonstrate that pulsed electric fields enable growth factor release for all these biological matrices generated using whole blood from four human donors. These experiments open opportunities for using electrically stimulated PRP with released growth factors without clotting for injectable platelet treatments in relevant clinical applications.

Soluble Platelet Release Factors as Biomarkers for Cardiovascular Disease

Platelets are the main players in thrombotic diseases, where activated platelets not only mediate thrombus formation but also are involved in multiple interactions with vascular cells, inflammatory components, and the coagulation system. Although in vitro reactivity of platelets provides information on the function of circulating platelets, it is not a full reflection of the in vivo activation state, which may be relevant for thrombotic risk assessment in various disease conditions. Therefore, studying release markers of activated platelets in plasma is of interest. While this type of study has been done for decades, there are several new discoveries that highlight the need for a critical assessment of the available tests and indications for platelet release products. First, new insights have shown that platelets are not only prominent players in arterial vascular disease, but also in venous thromboembolism and atrial fibrillation. Second, knowledge of the platelet proteome has dramatically expanded over the past years, which contributed to an increasing array of tests for proteins released and shed from platelets upon activation. Identification of changes in the level of plasma biomarkers associated with upcoming thromboembolic events allows timely and individualized adjustment of the treatment strategy to prevent disease aggravation. Therefore, biomarkers of platelet activation may become a valuable instrument for acute event prognosis. In this narrative review based on a systematic search of the literature, we summarize the process of platelet activation and release products, discuss the clinical context in which platelet release products have been measured as well as the potential clinical relevance.

Impact of specific preclinical variables on coagulation biomarkers in cancer-associated thrombosis

Coagulation biomarkers are being actively studied for their diagnostic and prognostic value in patients with venous thromboembolism and cancer, as well as in the study of pathogenic mechanisms between cancer and thrombosis. For the results of such studies to be accurate and reproducible, attention must be paid to minimize sources of error in all phases of testing. The pre-analytical phase of laboratory testing is known to be fraught with the majority of errors. Coagulation testing is particularly susceptible to conditions during collection, processing, transport and storage of specimens which can lead to clinically significant errors in results. In addition, changes in pre-analytical conditions can impact different biomarkers differently. Therefore, research studies investigating coagulation biomarkers must carefully standardize not just the analytical phase, but also the pre-analytical phase of testing to ensure accuracy and reliability. We briefly review the impact of pre-analytical conditions on coagulation testing in general, and on specific biomarkers in cancer and thrombosis. In addition, we provide recommendations to reduce pre-analytical errors by developing and sharing standard operating procedures that specifically target standardization of methodologies for collecting specimens and measuring current and emerging coagulation biomarkers in cancer studies.

Hemin-induced platelet activation and ferroptosis is mediated through ROS-driven proteasomal activity and inflammasome activation: Protection by Melatonin

Reactive oxygen species (ROS) are capable of inducing cell death or apoptosis. Recently, we demonstrated that lipid-ROS can mediate ferroptosis and activation of human platelets. Ferroptosis is an intracellular iron-mediated cell death, distinct from classical apoptosis and necrosis, which is mediated through the accumulation of ROS, lipid peroxides and depletion of cellular GSH. Lately, we demonstrated that hemoglobin degradation product hemin induces ferroptosis in platelets via ROS and lipid peroxidation. In this study, we demonstrate that hemin-induced ferroptosis in platelets is mediated through ROS-driven proteasome activity and inflammasome activation, which were mitigated by Melatonin (MLT). Although inflammasome activation is linked with pyroptosis, it is still not clear whether ferroptosis is associated with inflammasome activation. Our study for the first time demonstrates an association of platelet activation/ferroptosis with proteasome activity and inflammasome activation. Although, high-throughput screening has recognized ferrostatin-1 (Fer-1) and liproxstatin-1 (Lip-1) as potent ferroptosis inhibitors, having an endogenous antioxidant such as MLT as ferroptosis inhibitor is of high interest. MLT is a well-known chronobiotic hormone that regulates the circadian rhythms in vertebrates. It also exhibits potent antioxidant and ROS quenching capabilities. MLT can regulate fundamental cellular functions by exhibiting cytoprotective, oncostatic, antiaging, anti-venom, and immunomodulatory activities. The ROS scavenging capacity of MLT is key for its cytoprotective and anti-apoptotic properties. Considering the anti-ferroptotic and anti-apoptotic potentials of MLT, it could be a promising clinical application to treat hemolytic, thrombotic and thrombocytopenic conditions. Therefore, we propose MLT as a pharmacological and therapeutic agent to inhibit ferroptosis and platelet activation.

Platelet number in different anticoagulants as a diagnostic biomarker for increased intestinal permeability

The main pathological process associated to increased intestinal permeability is the translocation of toxic products, predominantly endotoxins/lipopolysaccharide (LPS), from the intestinal tract into the microcirculation. In blood, LPS binds to surface receptors on immune cells initiating an inflammatory response. LPS can also bind to platelets leading to preactivated platelets that have a lower threshold to be aggregated in presence heparin. The aim of this study was to validate a simple, fast and reliable test for screening LPS-loaded platelets. This test named PANDA (acronym for Platelet Number in Different Anticoagulants) consists in the measurement of the mean platelet number in blood samples collected into EDTA and heparin. We analyzed blood samples from 92 patients with gastrointestinal diseases and 23 healthy volunteers and found a markedly low number of platelets in heparinized blood compared to EDTA-anticoagulated blood in patients but not in healthy volunteers. Furthermore, ex vivo addition of endotoxin to blood samples induced a remarkable decrease in platelet count in heparinized blood of the volunteers but not in the patient's group, where platelets could be previously saturated by endotoxin circulating in blood. Platelet should be counted during the first hour after blood collection, in order to avoid false results due to a progressive platelet aggregation in heparinized blood in function of the time. Our results demonstrated that PANDA test can be used for screening LPS-loaded platelets as an indirect diagnostic biomarker for increased intestinal permeability and also for monitoring the gut barrier function during the treatment of gastrointestinal diseases.

Platelets as Predictors of Vascular Risk: Is There a Practical Index of Platelet Activity?

Activated platelets play a role in the pathogenesis of coronary heart disease (CHD). Following activation, platelets change shape, aggregate, and release several bioactive substances. The aim of this review is to identify if there is a simple and cost-effective method that indicates platelet activation and predicts the risk of CHD and vascular events. The rationale for identifying high-risk patients is to reduce their risk of vascular events by administering appropriate and effective antiplatelet treatment, like aspirin, clopidogrel, or combination regimens. Many laboratory tests estimating platelet activity have been described. Some are relatively simple, such as spontaneous or agonist-induced platelet aggregation. Other tests include measuring the mean platelet volume (MPV) or plasma soluble P-selectin levels. Some more complex tests include flow cytometry to determine platelet GP Ilb/Illa receptors, platelet surface P-selectin, plateletmonocyte aggregates, and microparticles. Only few prospective studies assessed the predictive value of platelet activation in healthy individuals. Although the MPV seems an 'easy method, there are insufficient data supporting its ability to predict the risk of a vascular event in healthy adults. Platelet aggregation, in whole blood or in platelet-rich plasma was not consistently predictive of vascular risk. Soluble P-selectin measurement is a promising method but it needs further evaluation. Flow cytometry methods are costly, time-consuming, and need specialized equipment. Thus, they are unlikely to be useful in estimating the risk in large numbers of patients. There is as yet no ideal test for the detection of platelet activation. Each currently available test has merits and disadvantages. Simple methods such as the MPV and the determination of platelet release products need further evaluation.

N-ethylmaleimide‑sensitive factor siRNA inhibits the release of Weibel-Palade bodies in endothelial cells

The aim of the present study was to examine the effect of small interfering RNA (siRNA) methods on the expression of N‑ethylmaleimide sensitive factor (NSF) and Weibel‑Palade body (WPB) release in endothelial cells. A small hairpin RNA (shRNA), mediated with an adenovirus vector, was designed to target the N‑terminal functional area of NSF. Subsequently, viruses were transfected into human aortic endothelial cells. The mRNA and protein expression levels of NSF were detected using reverse transcription‑quantitative polymerase chain reaction and Western blot analyses, respectively, and the release of WPBs in the endothelial cells was examined using immunofluorescence. The mRNA expression of NSF in the endothelial cells, which were transfected with the adenoviruses carrying the NSF‑shRNA was significantly decreased, compared with the negative control group (P=0.035) and blank control group (P=0.02). In addition, the mRNA expression of NSF was gradually decreased as duration increased; there were marked differences between the 24, 48 and 72 h groups (P<0.05). The protein expression of NSF was significantly decreased in the experimental group, compared with the negative control group (P=0.004) and blank control group (P=0.031), however, no difference was observed between the negative control and blank control groups (P=0.249). The immunofluorescence staining showed that the release of WPBs in the endothelial cells induced with thrombin was inhibited markedly following transfection with the virus carrying the NSF‑shRNA. Therefore NSF‑siRNA inhibited the mRNA and protein expression levels of NSF, and inhibited the release of WPBs in endothelial cells induced with thrombin. These results suggested that NSF-siRNA may be valuable for preventing and treating atherosclerosis and acute coronary syndrome.

Association of ABO blood group with P-selectin levels in Chinese Han healthy volunteers

BACKGROUND

Recent genome-wide association studies in Caucasians suggested that an association exists between the ABO gene locus and soluble levels of P-selectin (sP-selectin). However, it is unclear if the relationship corresponds to the phenotypic expression of ABO groups or is present in different ethnic groups. The aim of this study was to verify this observation at both genotypic and phenotypic levels in a healthy Chinese population.

STUDY DESIGN AND METHODS

The ABO blood groups were determined by both phenotypes and genotypes in 440 healthy Chinese Han volunteers, while P-selectin levels were evaluated for sP-selectin and total platelet P-selectin (pP-selectin).

RESULTS

ABO phenotyping and quantitative analysis of individual sP-selectin plasma levels were combined to demonstrate that individuals phenotypically expressing the A antigen have approximately 20% lower sP-selectin plasma levels than those carrying the B or O phenotype (p < 0.0001), but that no difference exists between A and AB and between B and O phenotypes. Genotyping data revealed that the presence of the A gene could be attributed to the observed difference in phenotype comparison, with no difference between A/A, A/B, and A/O genotypes. There were also no associations between ABO blood groups, either phenotypes or genotypes, and pP-selectin levels.

CONCLUSION

This study demonstrated an association between sP-selectin levels and ABO groups in a Chinese Han population, implicating its generalizability to other ethnic groups. This finding will improve the understanding of the mechanism of ABO blood group-associated diseases.

The effect of a polyurethane coating incorporating both a thrombin inhibitor and nitric oxide on hemocompatibility in extracorporeal circulation

Nitric oxide (NO) releasing (NORel) materials have been extensively investigated to create localized increases in NO concentration by the proton driven diazeniumdiolate-containing polymer coatings and demonstrated to improve extracorporeal circulation (ECC) hemocompatibility. In this work, the NORel polymeric coating composed of a diazeniumdiolated dibutylhexanediamine (DBHD-N2O2)-containing hydrophobic Elast-eon™ (E2As) polyurethane was combined with a direct thrombin inhibitor, argatroban (AG), and evaluated in a 4 h rabbit thrombogenicity model without systemic anticoagulation. In addition, the immobilizing of argatroban to E2As polymer was achieved by either a polyethylene glycol-containing (PEGDI) or hexane methylene (HMDI) diisocyanate linker. The combined polymer film was coated on the inner walls of ECC circuits to yield significantly reduced ECC thrombus formation compared to argatroban alone ECC control after 4 h blood exposure (0.6 ± 0.1 AG/HMDI/NORel vs 1.7 ± 0.2 cm(2) AG/HMDI control). Platelet count (2.8 ± 0.3 AG/HMDI/NORel vs 1.9 ± 0.1 × 10(8)/ml AG/HMDI control) and plasma fibrinogen levels were preserved after 4 h blood exposure with both the NORel/argatroban combination and the AG/HMDI control group compared to baseline. Platelet function as measured by aggregometry remained near normal in both the AG/HMDI/NORel (63 ± 5%) and AG/HMDI control (58 ± 7%) groups after 3 h compared to baseline (77 ± 1%). Platelet P-selectin mean fluorescence intensity (MFI) as measured by flow cytometry also remained near baseline levels after 4 h on ECC to ex vivo collagen stimulation (16 ± 3 AG/HMDI/NORel vs 11 ± 2 MFI baseline). These results suggest that the combined AG/HMDI/NORel polymer coating preserves platelets in blood exposure to ECCs to a better degree than AG/PEGDI/NORel, NORel alone or AG alone. These combined antithrombin, NO-mediated antiplatelet effects were shown to improve thromboresistance of the AG/HMDI/NORel polymer-coated ECCs and move potential nonthrombogenic polymers closer to mimicking vascular endothelium.

Effects of soy isoflavone extract supplements on blood pressure in adult humans: systematic review and meta-analysis of randomized placebo-controlled trials

OBJECTIVE

Reported effects of different soy products on blood pressure vary. This systematic review and meta-analysis was performed to clarify the effects of soy isoflavone extract supplements on systolic and diastolic blood pressure (SBP and DBP) in adult humans.

METHODS

PubMed, CENTRAL, ICHUSHI, and CNKI were searched in June 2009 for relevant randomized placebo-controlled trials. Study data and indicators of methodological validity were independently extracted by two authors using predefined data fields. Meta-analysis was carried out in Review Manager 5.0.22.

RESULTS

Searches identified 3740 articles, of which 14 randomized controlled trials (789 participants) were included. Daily ingestion of 25-375 mg soy isoflavones (aglycone equivalents) for 2-24 weeks significantly decreased SBP by 1.92 mmHg (95% confidence interval -3.45 to -0.39; P = 0.01) compared with placebo (heterogeneity P = 0.39, fixed effect model) in adults with normal blood pressure and prehypertension. The effect was not lost on sensitivity analysis. Subgroup analyses suggest greater effects in studies longer than 3 months, in Western populations, at lower doses, and in studies at lower risk of bias. Soy isoflavones did not affect DBP [-0.13 (95% confidence interval -1.03 to 0.78) mmHg, P = 0.78; heterogeneity P = 0.20, fixed effect model].

CONCLUSION

Soy isoflavone extracts significantly decreased SBP but not DBP in adult humans, and no dose-response relationship was observed. Further studies are needed to address factors related to the observed effects of soy isoflavones on SBP and to verify the effect in hypertensive patients.

A proteomic approach for plasma biomarker discovery with iTRAQ labelling and OFFGEL fractionation

Human blood plasma contains a plethora of proteins, encompassing not only proteins that have plasma-based functionalities, but also possibly every other form of low concentrated human proteins. As it circulates through the tissues, the plasma picks up proteins that are released from their origin due to physiological events such as tissue remodeling and cell death. Specific disease processes or tumors are often characterized by plasma “signatures,” which may become obvious via changes in the plasma proteome profile, for example, through over expression of proteins. However, the wide dynamic range of proteins present in plasma makes their analysis very challenging, because high-abundance proteins tend to mask those of lower abundance. In the present study, we used a strategy combining iTRAQ as a reagent which improved the peptide ionization and peptide OFFGEL fractionation that has already been shown, in our previous research, to improve the proteome coverage of cellular extracts. Two prefractioning methods were compared: immunodepletion and a bead-based library of combinatorial hexapeptide technology. Our data suggested that both methods were complementary, with regard to the number of identified proteins. iTRAQ labelling, in association with OFFGEL fractionation, allowed more than 300 different proteins to be characterized from 400 μg of plasma proteins.

Role of platelet-rich plasma in acceleration of bone fracture healing

Platelet-rich plasma (PRP) is a common therapy for acceleration of maxillofacial and spinal fusion bone-graft healing. This study analyzes the therapeutic role of PRP during long-bone fracture healing evaluated Lewis rats. Following creation of unilateral open femur fractures, either 500 microL thrombin-activated PRP (PRP treated group) or 500 microL saline (control group) were applied once to the fracture site. Fracture healing was analyzed after 1 and 4 weeks. Following 4 weeks of fracture healing, radiographic analysis demonstrated higher callus to cortex width ratio (P < 0.05) in the PRP group (PRP: 1.65 +/- 0.06; control: 1.48 +/- 0.05). Three-point load bearing showed increased bone strength following PRP treatment (PRP: 60.85 +/- 6.06 Newton, control: 47.66 +/- 5.49 Newton). Fracture histology showed enhanced bone formation in the PRP group. Immunohistochemistry and Western-blotting demonstrated healing-associated changes in transforming growth factor (TGF)-beta1 and bone morphogenetic protein (BMP)-2. Our results suggest that PRP accelerates bone fracture healing of rat femurs via modulation of TGF-beta1 and BMP-2 growth factor expression.

Tissue factor upregulation drives a thrombosis-inflammation circuit in relation to cardiovascular complications

The extrinsic coagulation is recognized as an 'inducible' signalling cascade resulting from tissue factor (TF) upregulation by exposure to clotting zymogen FVII upon inflammation or tissue injury. Following the substantial initiation, an array of proteolytic activation generates mediating signals (active serine proteases: FVIIa, FXa and FIIa) that lead to hypercoagulation with fibrin overproduction manifesting thrombosis. In addition, TF upregulation plays a central role in driving a thrombosis-inflammation circuit. Coagulant mediators (FVIIa, FXa and FIIa) and endproduct (fibrin) are proinflammatory, eliciting tissue necrosis factor, interleukins, adhesion molecules and many other intracellular signals in different cell types. Such resulting inflammation could ensure 'fibrin' thrombosis via feedback upregulation of TF. Alternatively, the resulting inflammation triggers platelet/leukocyte/polymononuclear cell activation thus contributing to 'cellular' thrombosis. TF is very vulnerable to upregulation resulting in hypercoagulability and subsequent thrombosis and inflammation, either of which presents cardiovascular risks. The prevention and intervention of TF hypercoagulability are of importance in cardioprotection. Blockade of inflammation reception and its intracellular signalling prevents TF expression from upregulation. Natural (activated protein C, tissue factor pathway inhibitor, or antithrombin III) or pharmacological anticoagulants readily offset the extrinsic hypercoagulation mainly through FVIIa, FXa or FIIa inhibition. Therefore, anticoagulants turn off the thrombosis-inflammation circuit, offering not only antithrombotic but anti-inflammatory significance in the prevention of cardiovascular complications.

Effects of soy isoflavones on endothelial function in healthy postmenopausal women

OBJECTIVE

To evaluate the effects of soy isoflavone administration on endothelial function in healthy postmenopausal women.

DESIGN

Sixty naturally postmenopausal women were randomly assigned to receive isoflavone or placebo tablets for 6 months. Endothelium-dependent vasodilatation was measured by brachial reactivity technique along with levels of plasma soluble intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, P-selectin and soluble thrombomodulin, von Willebrand factor, and tissue plasminogen activator. Differences between endothelium-dependent and endothelium-independent vasodilatation were assessed by evaluating brachial reactivity parameters after reactive hyperemia and after sublingual administration of nitroglycerin; furthermore, in the active group, the effect of isoflavones was also evaluated during the intra-arterial infusion of N-monomethyl-L-arginine. Serum levels of lipids [high-density lipoprotein and low-density lipoprotein cholesterol, triglycerides and lipoprotein(a)] and hemostatic factors (prothrombin, fibrinogen, plasminogen activator inhibitor-1, and fibrin D-dimer) were also measured. To confirm the absorption of isoflavones, their blood concentrations were determined.

RESULTS

Isoflavone treatment versus placebo was associated with a significant improvement in endothelium-dependent vasodilatation but had no impact on endothelial-independent arterial diameter and flow. Intra-arterial infusion of N-monomethyl-L-arginine inhibited the significant effect of isoflavones on endothelium-mediated vasodilatation. Furthermore, isoflavone group experienced statistically significant reductions in plasma concentrations of ICAM-1, VCAM-1, and E-selectin. Levels of soluble thrombomodulin, von Willebrand factor, tissue plasminogen activator, lipids, and hemostatic factors did not change significantly throughout the study in both groups.

CONCLUSIONS

Our findings suggest a positive influence of soy isoflavones on endothelial function in healthy postmenopausal women as evidenced by an improvement in endothelium-dependent vasodilatation and a reduction in plasma adhesion molecule levels.

Effects of transdermal hormone replacement therapy on levels of soluble P- and E-selectin in postmenopausal healthy women

OBJECTIVE

To study the adhesion molecule pattern in postmenopausal women who were not receiving hormone replacement therapy (HRT), HRT users, and fertile women.

DESIGN

Case-control study.

SETTING

Second University of Naples, Naples, Italy.

PATIENT(S)

Fifty healthy naturally postmenopausal women and 20 fertile women.

INTERVENTION(S)

Twenty-six women received no HRT and 24 received continuous transdermal 17 beta-estradiol, 0.05 mg/d, plus oral acetate nomegestrol, 5 mg/d.

MAIN OUTCOME MEASURE(S)

Levels of the soluble forms of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and P-selectin.

RESULT(S)

Women who did not received HRT showed a trend toward higher levels of soluble E-selectin and had significantly higher levels of soluble P-selectin than did fertile women. Levels of soluble E-selectin and soluble P-selectin were significantly lower in HRT users than in nonusers. Levels of VCAM-1 levels were significantly higher in HRT users than in fertile women, but no significant differences in CAM concentrations were found between the other groups.

CONCLUSION(S)

Menopause may lead to increased levels of soluble E- and soluble P-selectin, whereas long-term HRT is associated with lower selectin concentrations. This suggests that HRT may have a beneficial effect on endothelial function.

Plasma markers of endothelial dysfunction in pulmonary hypertension

STUDY OBJECTIVES

To evaluate and to correlate endothelial cell dysfunction, using recently available plasma markers, with the magnitude of pulmonary artery pressure in patients with severe pulmonary hypertension (PH).

DESIGN

Selected plasma markers of endothelial cell dysfunction were studied: nitric oxide (NO), thrombomodulin, tissue factor pathway inhibitor, and soluble endothelium, leukocyte, and platelet selectins (sE-, sL-, sP-selectins, respectively).

SETTING

Padova University Hospital and Department of Pathology and Pharmacology, Loyola University of Chicago, Chicago, IL.

PATIENTS

Fifteen patients had severe PH (four men and 11 women; mean age, 49.7 +/- 2.9 years: seven patients had primary pulmonary hypertension [PPH] and eight patients had secondary pulmonary hypertension [SPH]), and 20 patients were healthy control subjects.

MEASUREMENT AND RESULTS

In patients with PH, sP- and sE-selectins were elevated, whereas sL-selectin was lower in comparison with the selectin levels in control subjects. However, the differences between patients with PH and control subjects were significant only for sL-selectin (p < 0.0001) and sE-selectin (p < 0.03). The NO level was significantly lower in patients with PH compared with the NO level in control subjects (p < 0.01). No difference in tissue factor pathway inhibitor level was noted between control subjects and patients with PH. Only a weak correlation was found between thrombomodulin plasma levels and magnitude of systolic pulmonary artery pressure (r = -0.528, p < 0.05).

CONCLUSIONS

Our data are in keeping with the evidence for significant endothelial cell dysfunction in patients with PH and the need for chronic anticoagulation believed to increase survival in these patients. In addition, these data seem to suggest a need for newer agents that are able to increase the antithrombotic endothelial function.

Plasma markers of endothelial dysfunction in chronic obstructive pulmonary disease

We studied some endothelial cell activity plasma markers, nitric oxide (NO), thrombomodulin (TM), selectins (sP-, sE-, sL-selectin: platelet-P, endothelium-E, leukocyte-L), and tissue factor pathway inhibitor (TFPI) in 14 patients with chronic obstructive pulmonary disease (COPD), matched with 20 normal controls, to evaluate their endothelial cell dysfunction. Both NO (patients: 23.42 +/- 1.67 microg/mL: controls: 40.0 +/- 3.38 microg/mL) and TM levels (patients: 5.46 +/- 1.32 ng/mL; controls: 12.9 +/- 0.51 ng/mL) were significantly decreased in COPD (p < 0.001). sP-selectin levels (patients: 79.42 +/- 18.20 ng/mL, controls: 37.5 +/- 2.84 mg/mL) were significantly higher (p < 0.02), whereas sL-selectin levels (patients: 584.9 +/- 78.98 ng/mL, controls: 1,054.02 +/- 61.28 ng/mL) were significantly decreased in patients with COPD (p < 0.001). In contrast, no differences were seen in sE-selectin. Patients with COPD showed a significantly higher (p < 0.001) TFPI antigen plasma level (mean 112.28 +/- 6 .45 ng/mL; controls 77.68 +/- 0.28 ng/mL) than controls. Our data support the concept of some form of endothelial cell dysfunction, and coagulation abnormalities are present in patients with COPD. However, because the endothelium seems to produce a defense mechanism, the potential usefulness of an antithrombotic therapy in these patients needs further investigation.