Microparticles: potential new contributors to the pathogenesis of systemic sclerosis?

BACKGROUND

Microparticles (MPs) are membrane-derived vesicles released from cells undergoing activation or apoptosis with diverse proinflammatory and prothrombotic activities, that have been implicated in the pathogenesis of systemic sclerosis (SSc). We aimed to evaluate the plasma levels of platelet-derived microparticles (PMPs), endothelial cell-derived microparticles (EMPs), and monocyte-derived microparticles (MMPs) in SSc patients, and the association between MPs and the clinical features of SSc.

METHODS

In this cross-sectional study, 70 patients with SSc and 35 age- and sex-matched healthy controls were evaluated. Clinical and nailfold capillaroscopy (NFC) data were obtained from all patients. Plasma levels of PMPs (CD42⁺/31⁺), EMPs (CD105⁺), and MMPs (CD14⁺) were quantified by flow cytometry.

RESULTS

Patients were mainly females (90%), with a mean age of 48.9 years old. PMP, EMP, and MMP levels were significantly increased in SSc patients compared to controls (79.2% ± 17.3% vs. 71.0% ± 19.8%, p = 0.033; 43.5% ± 8.7% vs. 37.8% ± 10.4%, p = 0.004; and 3.5% ± 1.3% vs. 1.1% ± 0.5%, p < 0.0001, respectively). PMP levels were significantly higher in patients with positive anti-topoisomerase-I antibodies (p = 0.030) and in patients with a disease duration > 3 years (p = 0.038). EMP levels were lower in patients with a higher modified Rodnan skin score (p = 0.015), and in those with an avascular score > 1.5 in NFC (p = 0.042).

CONCLUSION

The increased levels of PMPs, EMPs and MMPs in scleroderma patients might indicate a possible role for these agents in the pathogenesis of this challenging disease.

Microparticles-Mediated Vascular Inflammation and its Amelioration by Antioxidant Activity of Baicalin

Microparticles (MPs) are extracellular vesicles (0.1–1.0 μm in size), released in response to cell activation or apoptosis. Endothelial microparticles (EC-MP), vascular smooth muscle cell microparticles (VSMC-MP), and macrophage microparticles (MØ-MP) are key hallmarks of atherosclerosis progression. In our current study, we investigated the potent antioxidant activity of baicalin to ameliorate MP-induced vascular smooth muscle cell (VSMC) dysfunction and endothelial cell (EC) dysfunction, as well as the production of inflammatory mediators in macrophage (RAW264.7). In our study, baicalin suppressed the apoptosis, reactive oxygen species (ROS) generation, NO production, foam cell formation, protein expression of inducible nitric oxide synthase and cyclooxygenase-2 in MØ-MP-induced RAW264.7. In addition, VSMC migration induced by VSMC-MP was dose-dependently inhibited by baicalin. Likewise, baicalin inhibits metalloproteinase-9 expression and suppresses VSMC-MP-induced VSMC proliferation by down-regulation of mitogen-activated protein kinase and proliferating cell nuclear antigen protein expressions. Baicalin also inhibited ROS production and apoptosis in VSMC. In EC, the marker of endothelial dysfunction (endothelial senescence, upregulation of ICAM, and ROS production) induced by EC-MP was halted by baicalin. Our results suggested that baicalin exerts potent biological activity to restore the function of EC and VSMC altered by their corresponding microparticles and inhibits the release of inflammation markers from activated macrophages.

Laboratory options for risk assessment of pregnancy pathologies

The most effective method of screening for chromosomal abnormalities and evaluating the risk of pregnancy pathologies in the first trimester is combined screening. The algorithm of screening is based on the combination of maternal age, measuring of the nuchal translucency and the fetal heart rate and analysis of the placental products of free ß-hCG and PAPP-A. For the screening of preeclampsia, placental growth factor (PlGF) is added. To distinguish between preeclampsia and other pathologies caused by placental dysfunction it is recommended to also extend the screening with selected immunological markers. We concluded that elevated biochemical and immunological markers can help to predict the threat of preeclampsia in the third trimester. Some markers can probably predict the development of particularly severe pathological conditions.

Inside(sight) of tiny communicator: exosome biogenesis, secretion, and uptake

Discovered in the late 1980s as an extracellular vesicle of endosomal origin secreted from reticulocytes, exosomes recently gained scientific attention due to its role in intercellular communication. Exosomes have now been identified to carry cell-specific cargo of nucleic acids, proteins, lipids, and other biologically active molecules. Exosomes can be selectively taken up by neighboring or distant cells, which has shown to result in structural and functional responses in the recipient cells. Recent advances indicate the regulation of exosomes at various steps, including their biogenesis, selection of their cargo, as well as cell-specific uptake. This review will shed light on the differences between the type of extracellular vesicles. In this review, we discuss the recent progress in our understanding of the regulation of exosome biogenesis, secretion, and uptake.

Microparticles in systemic sclerosis, targets or tools to control fibrosis: This is the question!

Systemic sclerosis is the main systemic fibrotic disease with unknown etiology characterized by peripheral microvascular injury, activation of immune system, and wide-spread progressive fibrosis. Microparticles can be derived from any cell type during normal cellular differentiation, senescence, and apoptosis, and also upon cellular activation. Carrying along a broad range of surface cytoplasmic and nuclear molecules of originating cells, microparticles are closely implicated in inflammation, thrombosis, angiogenesis, and immunopathogenesis. Recently, microparticles have been proposed as biomarkers of endothelial injury, which is the primary event in the genesis of tissue fibrosis. Microparticles may have a role in fostering endothelial to mesenchymal transition, thus giving a significant contribution to the development of myofibroblasts, the most important final effectors responsible for tissue fibrosis and fibroproliferative vasculopathy. Thanks to potent profibrotic mediators, such as transforming growth factor beta, platelet-derived growth factor, high mobility group box 1 protein, nicotinamide adenine dinucleotide phosphate oxidase 4, and antifibrotic agents, such as matrix metalloproteinases, microparticles may play an opposite role in fibrosis.

Increased erythrocyte- and platelet-derived microvesicles in newly diagnosed type 2 diabetes mellitus

AIM

To investigate the thrombotic microenvironment in early stages of type 2 diabetes mellitus measuring platelet-derived, endothelial-derived and erythrocyte-derived microvesicles.

METHODS

We recruited 50 newly diagnosed type 2 diabetes mellitus patients who did not receive glucose-lowering treatment except for metformin and 25 matched non-type 2 diabetes mellitus volunteers. Microvesicles were measured with flow cytometry, glycated haemoglobin with high-performance liquid chromatography and advanced glycation end products with enzyme-linked immunosorbent assay.

RESULTS

Type 2 diabetes mellitus patients showed significantly higher levels of platelet-derived microvesicles [195/μL (115-409) vs 110/μL (73-150), p = 0.001] and erythrocyte-derived microvesicles [26/μL (9-100) vs 9/μL (4-25), p = 0.007] compared to non-type 2 diabetes mellitus individuals. Platelet-derived microvesicles were positively associated with fasting blood glucose (p = 0.026) and glycated haemoglobin (p = 0.002). Erythrocyte-derived microvesicles were also positively associated with fasting blood glucose (p = 0.018) but not with glycated haemoglobin (p = 0.193). No significant association was observed between platelet-derived microvesicles (p = 0.126) or erythrocyte-derived microvesicles (p = 0.857) and advanced glycation end products. Erythrocyte-derived microvesicles predicted the presence of type 2 diabetes mellitus, independently of platelet-derived microvesicles.

CONCLUSION

In newly diagnosed type 2 diabetes mellitus, ongoing atherothrombosis is evident during the early stages as evidenced by increased microvesicles levels. Furthermore, the association with glycemic profile suggests that microvesicles represent not only a novel mechanism by which hyperglycemia amplifies thrombotic tendency in type 2 diabetes mellitus but also early markers of thrombosis highlighting the need for earlier management of hyperglycemia.

Short Communication: Apoptotic Membrane Microparticles Quantified by Fluorescent Bead-Based Assay Are Elevated in HIV and SIV Infections

Apoptotic membrane microparticles (MMPs) derived from dying cells of multiple cell origins are highly immunostimulatory and are indicative of global immune activation and cell death in a variety of diseases. In this study, we developed a flow cytometric bead assay to quantify annexin-V⁺ apoptotic (MMPs) in plasma from humans and rhesus macaques. With a combination of flow cytometry and pan-fluorescent beads, MMPs were enumerated in plasma specimens by adding a constant ratio of beads to initial fluid volumes and then calculating MMP/mL based on MMP-to-bead ratios. Using this straightforward assay, we found that circulating MMP quantifications were highly reproducible and similar in number between normal rhesus macaques and humans subjects. However, MMPs increased two- to threefold during HIV and simian immunodeficiency virus (SIV) infections and were positively associated with T cell immune activation. Collectively, we present a rapid bead-based assay for both humans and macaque models to quantify MMPs that could be an instigator and predictor of immune activation, which is a primary source of HIV/SIV disease.

The Methods of Choice for Extracellular Vesicles (EVs) Characterization

In recent years, extracellular vesicles (EVs) have become a subject of intense study. These membrane-enclosed spherical structures are secreted by almost every cell type and are engaged in the transport of cellular content (cargo) from parental to target cells. The impact of EVs transfer has been observed in many vital cellular processes including cell-to-cell communication and immune response modulation; thus, a fast and precise characterization of EVs may be relevant for both scientific and diagnostic purposes. In this review, the most popular analytical techniques used in EVs studies are presented with the emphasis on exosomes and microvesicles characterization.

Redox Proteomics and Platelet Activation: Understanding the Redox Proteome to Improve Platelet Quality for Transfusion

Blood banks use pathogen inactivation (PI) technologies to increase the safety of platelet concentrates (PCs). The characteristics of PI-treated PCs slightly differ from those of untreated PCs, but the underlying reasons are not well understood. One possible cause is the generation of oxidative stress during the PI process. This is of great interest since reactive oxygen species (ROS) act as second messengers in platelet functions. Furthermore, there are links between protein oxidation and phosphorylation, another mechanism that is critical for cell regulation. Current research efforts focus on understanding the underlying mechanisms and identifying new target proteins. Proteomics technologies represent powerful tools for investigating signaling pathways involving ROS and post-translational modifications such as phosphorylation, while quantitative techniques enable the comparison of the platelet resting state versus the stimulated state. In particular, redox cysteine is a key player in platelet activation upon stimulation by different agonists. This review highlights the experiments that have provided insights into the roles of ROS in platelet function and the implications for platelet transfusion, and potentially in diseases such as inflammation and platelet hyperactivity. The review also describes the implication of redox mechanism in platelet storage considerations.

Extracellular vesicles in blood, milk and body fluids of the female and male urogenital tract and with special regard to reproduction

Extracellular vesicles (EVs) are released from almost all cells and tissues. They are able to transport substances (e.g. proteins, RNA or DNA) at higher concentrations than in their environment and may adhere in a receptor-controlled manner to specific cells or tissues in order to release their content into the respective target structure. Blood contains high concentrations of EVs mainly derived from platelets, and, at a smaller amount, from erythrocytes. The female and male reproductive tracts produce EVs which may be associated with fertility or infertility and are released into body fluids and mucosas of the urogenital organs. In this review, the currently relevant detection methods are presented and critically compared. During pregnancy, placenta-derived EVs are dynamically detectable in peripheral blood with changing profiles depending upon progress of pregnancy and different pregnancy-associated pathologies, such as preeclampsia. EVs offer novel non-invasive diagnostic tools which may reflect the situation of the placenta and the foetus. EVs in urine have the potential of reflecting urogenital diseases including cancers of the neighbouring organs. Several methods for detection, quantification and phenotyping of EVs have been established, which include electron microscopy, flow cytometry, ELISA-like methods, Western blotting and analyses based on Brownian motion. This review article summarises the current knowledge about EVs in blood and cord blood, in the different compartments of the male and female reproductive tracts, in trophoblast cells from normal and pre-eclamptic pregnancies, in placenta ex vivo perfusate, in the amniotic fluid, and in breast milk, as well as their potential effects on natural killer cells as possible targets.

Recombinant tissue plasminogen activator enhances microparticle release from mouse brain-derived endothelial cells through plasmin

Thrombolysis with recombinant tissue plasminogen activator (rt-PA) is currently the only approved pharmacological strategy for acute ischemic stroke. However, rt-PA exhibits vascular toxicity mainly due to endothelial damage. To investigate the mechanisms underlying rt-PA-induced endothelial alterations, we assessed the role of rt-PA in the generation of endothelial microparticles (EMPs), emerging biological markers and effectors of endothelial dysfunction. The mouse brain-derived endothelial cell line bEnd.3 was used. Cells were treated with rt-PA at 20, 40 or 80μg/ml for 15 or 24h, and EMPs were quantified in the culture media using Annexin-V staining coupled with flow cytometry. Rt-PA enhanced EMP release from bEnd.3 cells with a maximal increase at the 40μg/ml dose for 24h (+78% compared to controls). Using tranexamic acid and aprotinin we demonstrated that plasmin is responsible for rt-PA-induced EMP release. The p38 MAPK inhibitor SB203580 and the poly(ADP-ribose)polymerase (PARP) inhibitor PJ34 also reduced rt-PA-induced EMP production, suggesting that p38 MAPK and PARP are downstream intracellular effectors of rt-PA/plasmin. Rt-PA also altered through plasmin the morphology and the confluence of bEnd.3 cells. By contrast, these changes did not implicate p38 MAPK and PARP. This study demonstrates that rt-PA induces the production of microparticles by cerebral endothelial cells, through plasmin, p38 MAPK and PARP pathways. Determining the phenotype of these EMPs to clarify their role on the endothelium in ischemic conditions could thus be of particular interest.

The expression of microvesicles in the blood of patients with Graves' disease and its relationship to treatment

OBJECTIVE

Graves' disease (GD) is an autoimmune disease characterized by the presence of circulating autoantibodies against thyroid-stimulating hormone (TSH) receptor. Despite extensive research, the pathogenic mechanisms remain unclear. Immune responses associated with the disease may lead to cell activation/apoptosis and the release of microvesicles (MVs) into the circulation. MVs can display biological activities which may aggravate GD further. We studied immune mechanisms in GD by investigating the numbers and phenotype of circulating MVs in patients before and after antithyroid therapy with thiamazole.

PATIENTS AND MEASUREMENTS

Samples were obtained from 15 patients with GD in the acute phase of hyperthyroidism and following 17-26 months treatment and 14 healthy controls. MVs from platelets, endothelial cells and monocytes exposing inflammation/activation markers (P-selectin, CD40 ligand, E-selectin and HMGB1) and MVs containing nuclear molecules were measured with flow cytometry.

RESULTS

Patients had elevated baseline values of MVs (P < 0·001 for all types of MVs), while the levels decreased during thiamazole treatment (P < 0·05 for all types of MVs). The majority of MV populations remained, however, significantly higher in patients after treatment compared to levels in controls.

CONCLUSIONS

GD patients have elevated levels of MVs that carry molecules with potential biological activities. MVs are significantly reduced after antithyroid treatment with thiamazole but still higher compared to levels in healthy controls. Assessment of MV levels and pattern may therefore provide additional information on underlying immune disturbances not obtained by measurements of hormone levels alone.

Elevated level of membrane microparticles in the disease of steroid-induced vascular osteonecrosis

As a common disease, osteonecrosis attracts more and more attention. In this paper, we investigated the relationship between the alterations of endothelial-derived and platelet-derived microparticles and the changes of coagulation and inflammation in the steroid-induced avascular osteonecrosis of femoral head using the rabbit model. We also explored the possible mechanism of the membrane particles associated with the development of the rabbit femoral head ischemic necrosis. With a 28-day continuous observation, the level of membrane microparticles was significantly heightened after methylprednisolone treatment. The coagulating and inflammatory factors also tended to increase. The data demonstrated that the levels of membrane microparticles had significantly individual differences, which meant the increased levels of membrane microparticles may be related to hypercoagulability, thrombosis, and inflammation in microcirculation and played an important role in steroid-induced osteonecrosis. It will be very useful and helpful to guide clinical trials.

A novel role for peptidylarginine deiminases in microvesicle release reveals therapeutic potential of PAD inhibition in sensitizing prostate cancer cells to chemotherapy

INTRODUCTION

Protein deimination, defined as the post-translational conversion of protein-bound arginine to citrulline, is carried out by a family of 5 calcium-dependent enzymes, the peptidylarginine deiminases (PADs) and has been linked to various cancers. Cellular microvesicle (MV) release, which is involved in cancer progression, and deimination have not been associated before. We hypothesize that elevated PAD expression, observed in cancers, causes increased MV release in cancer cells and contributes to cancer progression.

BACKGROUND

We have previously reported that inhibition of MV release sensitizes cancer cells to chemotherapeutic drugs. PAD2 and PAD4, the isozymes expressed in patients with malignant tumours, can be inhibited with the pan-PAD-inhibitor chloramidine (Cl-am). We sought to investigate whether Cl-am can inhibit MV release and whether this pathway could be utilized to further increase the sensitivity of cancer cells to drug-directed treatment.

METHODS

Prostate cancer cells (PC3) were induced to release high levels of MVs upon BzATP stimulation of P2X7 receptors. Western blotting with the pan-protein deimination antibody F95 was used to detect a range of deiminated proteins in cells stimulated to microvesiculate. Changes in deiminated proteins during microvesiculation were revealed by immunoprecipitation and immunoblotting, and mass spectrometry identified deiminated target proteins with putative roles in microvesiculation.

CONCLUSION

We report for the first time a novel function of PADs in the biogenesis of MVs in cancer cells. Our results reveal that during the stimulation of prostate cancer cells (PC3) to microvesiculate, PAD2 and PAD4 expression levels and the deimination of cytoskeletal actin are increased. Pharmacological inhibition of PAD enzyme activity using Cl-am significantly reduced MV release and abrogated the deimination of cytoskeletal actin. We demonstrated that combined Cl-am and methotrexate (MTX) treatment of prostate cancer cells increased the cytotoxic effect of MTX synergistically. Refined PAD inhibitors may form part of a novel combination therapy in cancer treatment.

Toll-like receptor 4 senses oxidative stress mediated by the oxidation of phospholipids in extracellular vesicles

Oxidative stress produced in response to infection or sterile injury activates the innate immune response. We found that extracellular vesicles (EVs) isolated from the plasma of patients with rheumatoid arthritis or secreted from cells subjected to oxidative stress contained oxidized phospholipids that stimulated cells expressing Toll-like receptor 4 (TLR4) in a manner dependent on its co-receptor MD-2. EVs from healthy subjects or reconstituted synthetic EVs subjected to limited oxidation gained the ability to stimulate TLR4-expressing cells, whereas prolonged oxidation abrogated this property. Furthermore, we found that 15-lipoxygenase generated hydro(pero)xylated phospholipids that stimulated TLR4-expressing cells. Molecular modeling suggested that the mechanism of activation of TLR4 by oxidized phospholipids in EVs was structurally similar to that of the TLR4 ligand lipopolysaccharide (LPS). This was supported by experiments showing that EV-mediated stimulation of cells required MD-2, that mutations that block LPS binding to TLR4 abrogated the stimulatory effect of EVs, and that EVs induced TLR4 dimerization. On the other hand, analysis of gene expression profiles showed that genes encoding factors that resolve inflammation were more abundantly expressed in responses to EVs than in response to LPS. Together, these data suggest that EVs act as an oxidative stress-induced endogenous danger signal that underlies the pervasive role of TLR4 in inflammatory diseases.

Pediatric Non-Alcoholic Fatty Liver Disease

The rapidly increasing prevalence of childhood obesity and its associated co-morbidities such as hypertriglyceridemia, hyper-insulinemia, hypertension, early atherosclerosis, metabolic syndrome, and non-alcoholic fatty liver disease are major public health concerns in many countries. Therefore the trends in child and adolescent obesity should be closely monitored over time, as in the near future, we may anticipate a major increase of young adults with the stigmata of the metabolic syndrome, and of the related non-alcoholic fatty liver disease (NAFLD), that may lead to non-alcoholic steatohepatitis.

Are microparticles the missing link between thrombosis and autoimmune diseases? Involvement in selected rheumatologic diseases

Microparticles (MPs) are membrane-bound vesicles with important physiologic effects. MPs exchange information intercellularly, with each kind of MP carrying antigens and receptors of the cells from which they originated. They are biologic effectors in inflammation, angiogenesis, vascular injury, and thrombosis. Thrombosis is generally caused by abnormalities in blood flow, blood composition, and/or properties of the vessel wall. Thrombosis is a well-described feature of cardiovascular disease and cerebrovascular disease. Accumulating evidence suggests that increased risk of thrombosis is also characteristic of autoimmune disorders and immune-mediated diseases affecting all age groups, although the older adults are most vulnerable. Current research has also implicated MPs as a source of autoantigenic nuclear material that can form immune complexes, activate the innate immune system, and may lead to autoimmunity. This review focuses on the contribution of MPs to both the pathogenesis of autoimmune diseases and, as the immune and coagulation systems are tightly linked, their role in hypercoagulability in the setting of autoimmunity in an aging population.

Syncytiotrophoblast vesicles show altered micro-RNA and haemoglobin content after ex-vivo perfusion of placentas with haemoglobin to mimic preeclampsia

Background

Cell-free foetal haemoglobin (HbF) has been shown to play a role in the pathology of preeclampsia (PE). In the present study, we aimed to further characterize the harmful effects of extracellular free haemoglobin (Hb) on the placenta. In particular, we investigated whether cell-free Hb affects the release of placental syncytiotrophoblast vesicles (STBMs) and their micro-RNA content.

Methods

The dual ex-vivo perfusion system was used to perfuse isolated cotyledons from human placenta, with medium alone (control) or supplemented with cell-free Hb. Perfusion medium from the maternal side of the placenta was collected at the end of all perfusion phases. The STBMs were isolated using ultra-centrifugation, at 10,000×g and 150,000×g (referred to as 10K and 150K STBMs). The STBMs were characterized using the nanoparticle tracking analysis, identification of surface markers and transmission electron microscopy. RNA was extracted and nine different micro-RNAs, related to hypoxia, PE and Hb synthesis, were selected for analysis by quantitative PCR.

Results

All micro-RNAs investigated were present in the STBMs. Mir-517a, mir-141 and mir-517b were down regulated after Hb perfusion in the 10K STBMs. Furthermore, Hb was shown to be carried by the STBMs.

Conclusion

This study showed that Hb perfusion can alter the micro-RNA content of released STBMs. Of particular interest is the alteration of two placenta specific micro-RNAs; mir-517a and mir-517b. We have also seen that STBMs may function as carriers of Hb into the maternal circulation.

Proteomic analysis of venous thromboembolism: an update

Venous thromboembolism is a complex, multifactorial disorder, the pathogenesis of which typically involves a variety of inherited or acquired factors. The multifactorial etiology of this disease and the partial correlation between genotype and prothrombotic phenotype limit greatly the value of genetic analysis in assessing thrombotic risk. The integration of several new 'omics' techniques enables a multifaceted and holistic approach to the study of venous thrombotic processes and pave the way to the search and identification of novel blood biomarkers and/or effectors of thrombus formation that can also be the possible future target of new anticoagulant and thrombolytic therapies for more personalized medicine. This review provides a comprehensive overview of the latest candidate proteomic biomarkers of venous thrombosis and of the proteomics studies relevant to its pathophysiology, some of which seem to confirm the existence of a common physiopathological basis for venous thromboembolism and atherothrombosis.

Anti-β2GPI antibodies stimulate endothelial cell microparticle release via a nonmuscle myosin II motor protein-dependent pathway

The antiphospholipid syndrome is characterized by thrombosis and recurrent fetal loss in patients with antiphospholipid antibodies (APLAs). Most pathogenic APLAs are directed against β2-glycoprotein I (β2GPI), a plasma phospholipid binding protein. One mechanism by which circulating antiphospholipid/anti-β2GPI antibodies may promote thrombosis is by inducing the release of procoagulant microparticles from endothelial cells. However, there is no information available concerning the mechanisms by which anti-β2GPI antibodies induce microparticle release. In seeking to identify proteins phosphorylated during anti-β2GPI antibody-induced endothelial activation, we observed phosphorylation of nonmuscle myosin II regulatory light chain (RLC), which regulates cytoskeletal assembly. In parallel, we observed a dramatic increase in the formation of filamentous actin, a two- to fivefold increase in the release of endothelial cell microparticles, and a 10- to 15-fold increase in the expression of E-selectin, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, and tissue factor messenger RNA. Microparticle release, but not endothelial cell surface E-selectin expression, was blocked by inhibiting RLC phosphorylation or nonmuscle myosin II motor activity. These results suggest that distinct pathways, some of which mediate cytoskeletal assembly, regulate the endothelial cell response to anti-β2GPI antibodies. Inhibition of nonmuscle myosin II activation may provide a novel approach for inhibiting microparticle release by endothelial cells in response to anti-β2GPI antibodies.

Circulating microparticles of glial origin and tissue factor bearing in high-grade glioma: a potential prothrombotic role

Venous thromboembolism (VTE) may complicate the clinical course of glioblastoma multiforme (GBM). Circulating microparticles (MPs) have been associated with cancer-related VTE. Sixty-one consecutive patients with GBM undergoing gross-total (41) or subtotal (20) surgical resection followed by radio-chemotherapy were prospectively evaluated. MPs numbers according to cellular origin and the procoagulant activity of annexin V positive (AV+) MPs (MP-activity) were measured before surgery and then 1 week and 1, 4, and 7 months after surgery. Glial (GFAP+) and endothelial (CD62E+) derived MPs, AV+ and tissue factor-bearing (TF+) MPs were measured using flow cytometry. Baseline levels of GFAP+/TF-, TF+/GFAP-, and GFAP+/TF+ MPs were significantly higher in GBM patients than in healthy controls, and significantly increased at each time point after surgery; at 7 months, a further significant increase over the level found a week after surgery was only seen in the subtotally resected patients. The number AV+/CD62E- MPs increased in GBM patients and correlated with MP activity. TF+/GFAP- MPs numbers were significantly higher in 11 GBM patients who developed VTE than in those who did not (p 0.04). TF+/GFAP- MPs levels above the 90th percentile (calculated in GBM patients without VTE) were associated with a higher risk of VTE (RR 4.17, 95% CI 1.57-11.03). In conclusion, the numbers of glial-derived and/or TF-bearing MPs were high in GBM patients both before and even more after the neoplasm was treated, especially in patients with subtotal resection likely according to disease progression. A contribution of TF+/GFAP- MPs to the risk of VTE is suggested.

Repeated supra-maximal sprint cycling with and without sodium bicarbonate supplementation induces endothelial microparticle release

Under normal homeostatic conditions, the endothelium releases microparticles (MPs), which are known to increase under stressful conditions and in disease states. CD105 (endoglin) and CD106 (vascular cell adhesion molecule-1) are expressed on the surface of endothelial cells and increased expression in response to stress may be observed. A randomised-controlled double-blinded study aimed to examine the use of endothelial MPs as a marker for the state of one's endothelium, as well as whether maintaining acid-base homeostasis affects the release of these MPs. This study tested seven healthy male volunteers, who completed a strenuous cycling protocol, with venous blood analysed for CD105+ and CD106+ MPs by flow cytometry at regular intervals. Prior to each trial participants consumed either 0.3 g·kg(-1) body mass of sodium bicarbonate (NaHCO3), or 0.045 g·kg(-1) body mass of sodium chloride (NaCl). A significant rise in endothelial CD105+ MPs and CD106+ MPs (p<0.05) was observed at 90 min post-exercise. A significant trend was shown for these MPs to return to resting levels 180 min post-exercise in both groups. No significance was found between experimental groups, suggesting that maintaining acid-base variables closer to basal levels has little effect upon the endothelial stress response for this particular exercise mode. In conclusion, strenuous exercise is accompanied by MP release and the endothelium is able to rapidly recover in healthy individuals, whilst maintaining acid-base homeostasis does not attenuate the MP release from the endothelium after exercise.

Structural alterations of the mucosa stroma in the Barrett's esophagus metaplasia-dysplasia-adenocarcinoma sequence

BACKGROUND AND AIM

Accumulating evidence suggests that the extracellular matrix play important roles in intercellular communications and contribute to the development of a number of diseases, including diseases of the gastrointestinal tract. The present study examined the structural characteristics and alterations of the extracellular matrix of the mucosa stroma in the Barrett's esophagus metaplasia-dysplasia-adenocarcinoma sequence.

METHODS

A total of 41 esophageal tissue specimens (15 esophageal adenocarcinoma, 10 Barrett's esophagus intestinal metaplasia, seven dysplasia and nine normal esophagus) were studied. The present study used transmission electron microscopy and computerized quantitative electron-microscopic analysis in order to investigate the characteristics of the extracellular matrix of the mucosa.

RESULTS

The study revealed that marked structural alterations of the mucosa stroma, relating to changes in the distribution and appearance of collagen fibers as well as to changes in numbers of matrix microvesicles, occur in Barrett's esophagus and esophageal adenocarcinoma. It was found that there were 3.1 times more microvesicles in the stroma in Barrett's esophagus than in the stroma of the normal esophagus (P<0.0001) and that there were 5.8 times more microvesicles in esophageal adenocarcinoma than in the normal esophagus (P<0.0001). There were 1.9 times more microvesicles in esophageal adenocarcinoma than in Barrett's esophagus (P=0.0043).

CONCLUSIONS

The study demonstrates distinctive alterations of the mucosa stroma extracellular matrix in the metaplasia-dysplasia-adenocarcinoma sequence. The findings suggest that the redistribution of collagen fibers and increases in numbers of matrix microvesicles may play roles in the formation of specialized intestinal metaplasia and the development of adenocarcinoma.

Circulating microparticles as disease-specific biomarkers of severity of inflammation in patients with hepatitis C or nonalcoholic steatohepatitis

BACKGROUND & AIMS

Microparticles released into the bloodstream upon activation or apoptosis of CD4(+) and CD8(+) T cells correlate with inflammation as determined by histologic analysis in patients with chronic hepatitis C (CHC). Patients with nonalcoholic fatty liver (NAFL) or nonalcoholic steatohepatitis (NASH) can be differentiated from those with CHC based on activation of distinct sets of immune cells in the liver.

METHODS

We compared profiles of circulating microparticles from patients with NAFL and NASH (n = 67) to those of CHC (n = 42), with healthy individuals (controls) using flow cytometry; the profiles were correlated with inflammation grade and fibrosis stage based on histologic analyses. We assessed the ability of the profiles to determine the severity of inflammation and fibrosis based on serologic and histologic analyses.

RESULTS

Patients with CHC had increased levels of microparticles from CD4(+) and CD8(+) T cells; the levels correlated with disease severity based on histologic analysis and levels of alanine aminotransferase. Patients with NAFL or NASH had significant increases in numbers of microparticles from invariant natural killer T cells and macrophages/monocytes (CD14(+)), which mediate pathogenesis of NASH. Microparticles from CD14(+) and invariant natural killer T cells correlated with levels of alanine aminotransferase and severity of NASH (based on histology). Levels of microparticles could differentiate between patients with NAFL or NASH and those with CHC, or either group of patients and controls (area under the receiver operating characteristic curves ranging from 0.56 to 0.99).

CONCLUSIONS

Quantification of immune cell microparticles from serum samples can be used to assess the extent and characteristics of hepatic inflammation in patients with chronic liver disease.

Increased shedding of microvesicles from intimal smooth muscle cells in athero-prone areas of the human aorta: implications for understanding of the predisease stage

OBJECTIVE

This study evaluated whether a change in the content of matrix microvesicles might occur at the preatherosclerotic stage.

METHODS

Applying quantitative electron microscopic and immunohistochemical analyses, two areas of grossly normal segments of the thoracic aorta were compared: atherosclerosis-prone (AP) areas, situated at the dorsal aspect of the aorta along the rows of intercostal branch origins, and atherosclerosis-resistant (AR) areas, situated at the corresponding sites of the ventral aspect of the aorta.

RESULTS

The electron microscopic analysis showed that there were 1.4 times more microvesicles in AP areas than AR areas (p = 0.019). It was found that matrix microvesicles originated as a result of blebbing and shedding of surface membranes of smooth muscle cells. A quantitative analysis of the expression of ADP-ribosylation factor 6 (ARF6), which is known to be involved in membrane trafficking and microvesicle formation, showed that ARF6 expression was 1.3 times higher in AP areas than that in AR areas (p = 0.006). There was a positive correlation between the content of matrix microparticles and the expression of ARF6 by intimal smooth muscle cells (r = 0.61; p < 0.0001).

CONCLUSION

The present study supports the concept that alterations of the arterial intima occur at the predisease stage.