Microparticles: biomarkers and beyond. Clin Sci (Lond). 2013;124:423-441. [PMID: 23249271 DOI: 10.1042/cs20120309]

Indoxyl Sulfate-Induced Extracellular Vesicles Released from Endothelial Cells Stimulate Vascular Smooth Muscle Cell Proliferation by Inducing Transforming Growth Factor-Beta Production

Vascular access stenosis predominantly occurs as a result of neointimal hyperplasia (NH) formation at the anastomosis. Moreover, in the presence of NH, transforming growth factor-beta (TGF-β) promotes vascular smooth muscle cell (VSMC) proliferation. Extracellular vesicles (EVs) released by endothelial cells are closely associated with vascular dysfunction. Here, we investigated the effects of EVs on TGF-β signaling and VSMC proliferation. Specifically, EVs were collected from the culture medium of indoxyl sulfate (IS)-treated human umbilical vein endothelial cells and used (2 × 106) to stimulate human aortic smooth muscle cells (SMCs) (1 × 106). Western blotting was performed to assess the levels of Akt, ERK1/2, p38 MAPK, and Smad3. BrdU proliferation assays, quantitative PCR, and ELISA assays were performed to evaluate SMC proliferation and TGF-β production. The IS-induced EVs stimulated the proliferation of aortic SMCs in a concentration-dependent manner. The EVs both contained TGF-β and promoted TGF-β production by SMCs by phosphorylating Akt, ERK1/2, p38 MAPK, and Smad3, which was significantly inhibited by an anti-TGF-β antibody. SMC proliferation was suppressed by both an anti-TGF-β antibody and inhibitors of the downstream factors. These results suggest that EVs are involved in the pathogenesis of vascular access stenosis by modulating TGF-β signaling in VSMCs under uremic conditions.

Endothelial Microparticles in Uremia: Biomarkers and Potential Therapeutic Targets

Endothelial microparticles (EMPs) are vesicles derived from cell membranes, which contain outsourced phosphatidylserine and express adhesion molecules, such as cadherin, intercellular cell adhesion molecule-1 (ICAM-1), E-selectin, and integrins. EMPs are expressed under physiological conditions and continue circulating in the plasma. However, in pathologic conditions their levels increase, and they assume a pro-inflammatory and pro-coagulant role via interactions with monocytes; these effects are related to the development of atherosclerosis. Chronic kidney dysfunction (CKD) characterizes this dysfunctional scenario through the accumulation of uremic solutes in the circulating plasma, whose toxicity is related to the development of cardiovascular diseases. Therefore, this review aims to discuss the formation of EMPs and their biological effects in the uremic environment. Data from previous research demonstrate that uremic toxins are closely associated with the activation of inflammatory biomarkers, cardiovascular dysfunction processes, and the release of EMPs. The impact of a decrease in circulating EMPs in clinical studies has not yet been evaluated. Thus, whether MPs are biochemical markers and/or therapeutic targets has yet to be established.

Loss of Renal Peritubular Capillaries in Hypertensive Patients Is Detectable by Urinary Endothelial Microparticle Levels

Hypertension, an important cause of chronic kidney disease, is characterized by peritubular capillary (PTC) loss. Circulating levels of endothelial microparticles (EMPs) reflect systemic endothelial injury. We hypothesized that systemic and urinary PTC-EMPs levels would reflect renal microvascular injury in hypertensive patients. We prospectively measured by flow cytometry renal vein, inferior vena cava, and urinary levels of EMPs in essential (n=14) and renovascular (RVH; n=24) hypertensive patients and compared them with peripheral blood and urinary levels in healthy volunteers (n=14). PTC-EMPs were identified as urinary exosomes positive for the PTC marker plasmalemmal-vesicle-associated protein. In 7 RVH patients, PTC and fibrosis were also quantified in renal biopsy, and in 18 RVH patients, PTC-EMPs were measured again 3 months after continued medical therapy with or without stenting (n=9 each). Renal vein and systemic PTC-EMPs levels were not different among the groups, whereas their urinary levels were elevated in both RVH and essential hypertension versus healthy volunteers (56.8%±12.7% and 62.8%±10.7% versus 34.0%±17.8%; both P≤0.001). Urinary PTC-EMPs levels correlated directly with blood pressure and inversely with estimated glomerular filtration rate. Furthermore, in RVH, urinary PTC-EMPs levels correlated directly with stenotic kidney hypoxia, histological PTC count, and fibrosis and inversely with cortical perfusion. Three months after treatment, the change in urinary PTC-EMPs levels correlated inversely with a change in renal function ( r=-0.582; P=0.011). Therefore, urinary PTC-EMPs levels are increased in hypertensive patients and may reflect renal microcirculation injury, whereas systemic PTC-EMPs levels are unchanged. Urinary PTC-EMPs may be useful as novel biomarkers of intrarenal capillary loss.

The role of extracellular vesicles in renal fibrosis

As a particularly important mediator of intercellular communication, extracellular vesicles (EVs) have been proved to be extensively involved in various system diseases over the past two decades, including in renal diseases. As is well-known, renal fibrosis is the common pathological process of any ongoing renal disease or adaptive repair of kidney injury based on current knowledge. Although much work has been performed focusing on EVs in various renal diseases, the role of EVs in renal fibrosis has not been described in detail and summarized. In this review, we provide a brief overview of the definition, classification and biological process of EVs. Then, the potential mechanisms of EVs in renal fibrosis are illustrated. Lastly, recent advances in EVs and the implications of EVs for diagnosis and therapy in renal fibrosis disease are introduced. We look forward to a more comprehensive understanding of EVs in renal fibrosis, which could be a boon to patients with renal fibrosis disease.

Retracted: Combined therapy using LHRH-PE40 and anti-CD40 dendritic cells substantially eliminate tumor cells

LHRH-PE40 was used to promote the proliferation of bone marrow derived cell (BMDC) and improve the antigen-presenting ability of BMDC as well as the immune function via the CD40 signal pathway. LHRH-PE40 was also implicated in cancer treatment, targeting a variety of cancer cells that express luteinizing hormone-releasing hormone receptor (LHRHR). In the present study, the mechanism and efficacy of LHRH-PE40 were addressed in the following three aspects. Enzyme-linked immunosorbent assay was performed to confirm the binding specificity of LHRH-PE40 to LHRHR. The killing effect of LHRH-PE40 on target cells was mediated by LHRHR, which specifically killed LHRHR-positive target cells while the minimal cytotoxicity of LHRHR-negative cells is negligible. Spiegelmers, a molecule mutually exclusive with GnRH and developed by Sven Klussmann and Dr Sven Klussmann of NOXXON Pharmaceuticals in Germany, demonstrated that LHRH-PE40 maintains a combinatory characteristics of LHRH and LHRHR. In the end, the mechanism of LHRH-PE40 underlying induction of apoptosis at low concentration and prolonged conditions was firstly demonstrated by the basic method of detecting apoptosis to induce apoptosis. It provided a scientific basis for clinical application of LHRH-PE40 and laid a foundation for the further study of LHRH-PE40 on inducing apoptosis of target cells. The target cells herein refer to tumor cells that overexpress LHRHR. This study shows that activated DC can more effectively promote the proliferation of CD4+ T cells, and initially proved that DC carrying anti-CD40 antibody promoted the immune treatment of the tumor. Combining LHRH-PE40 with anti-CD40 DCs achieved substantially improved efficacy in killing tumor cells.

Microparticles and cardiovascular diseases

Microparticles are a distinctive group of small vesicles, without nucleus, which are involved as significant modulators in several physiological and pathophysiological mechanisms. Plasma microparticles from various cellular lines have been subject of research. Data suggest that they are key players in development and manifestation of cardiovascular diseases and their presence, in high levels, is associated with chronic inflammation, endothelial damage and thrombosis. The strong correlation of microparticle levels with several outcomes in cardiovascular diseases has led to their utilization as biomarkers. Despite the limited clinical application at present, their significance emerges, mainly because their detection and enumeration methods are improving. This review article summarizes the evidence derived from research, related with the genesis and the function of microparticles in the presence of various cardiovascular risk factors and conditions. The current data provide a substrate for several theories of how microparticles influence various cellular mechanisms by transferring biological information.

Circulating microparticle subpopulation in metabolic syndrome: relation to oxidative stress and coagulation markers

BACKGROUND

Circulating microparticles (MPs) contribute to the pathogenesis of atherothrombotic disorders and are raised in cardiovascular diseases. Herein, we aimed to investigate the effect of moderate metabolic abnormalities in an early stage of metabolic syndrome (MetS) on the level of MP subpopulations and to study relationships between MP subpopulations and both oxidative stress and coagulation markers.

METHODS

Flow cytometry used to evaluate circulating MPs subpopulations in 40 patients with an early stage MetS and 30 healthy controls. ELISA was used to quantify plasminogen activator inhibitor type 1/tissue plasminogen activator (PAI-1/TPA) while plasma glutathione peroxidase (GPx) activity was measured spectrophotometrically.

RESULTS

Total MPs were significantly elevated in MetS (P<0.001). Glutathione peroxidase and PAI1/TPA activity was significantly increased in subjects with MetS (P<0.001). Waist circumference, diastolic blood pressure, and total cholesterol positively influenced levels of total MPs, platelet-derived microparticles, and endothelium-derived microparticles. Fasting blood glucose, cholesterol, triglycerides, and low-density lipoprotein positively influenced the coagulation factors (TPA, PAI1). However, high-density lipoprotein negatively influenced platelet-derived MPs and factors associated with fibrinolysis (TPA, PAI1).

CONCLUSION

Elevated circulating MPs are associated with MetS abnormalities, oxidative stress and coagulation factors and may act as early predictor of metabolic syndrome with risk of cardiovascular disease.

Biomarkers of radiation-induced vascular injury

OBJECTIVE

Cancer survivorship has thrown the spotlight on the incidence of nonmalignant chronic diseases in cancer patients. Endothelial injury is increasingly recognized as a consequence of cancer treatment, particularly after radiation therapy (RT). This review is to provide a current understanding on the pathophysiological mechanisms and predictive biomarkers of radiation-induced vascular injury.

RECENT FINDINGS

Radiation directly impacts vasculature by causing endothelial apoptosis and senescence, and alterations in normal homeostasis. This altered milieu at the endothelial surface may contribute to a systemic chronic inflammatory state that is superimposed upon the cascade of normal senescence processes leading to acceleration of age-related disorders, atherosclerosis, and chronic fibrosis. Vasculature imaging, blood-based or cell-component biomarkers, and signatures of genomics, proteomics, metabolomics, and radiomics are potential tools for detection of vascular damage after irradiation.

CONCLUSIONS

Development of a valid prediction model by combining an array of imaging tools, blood-based biomarkers, coupled with novel predictors like exosomes and metabolic degradation products can serve to identify RT-induced vascular injury early for subsequent introduction of newer therapeutic approaches to counter radiation morbidity.

Effects of resveratrol on laminar shear stress-induced mitochondrial biogenesis in human vascular endothelial cells

[Purpose]

The purpose of the study was to determine the combined effects of resveratrol supplementation with high-flow LSS on mitochondrial biogenesis in human vascular endothelial cells.

[Methods]

Cultured human umbilical vein endothelial cells were treated with 20 μM of RSV. For the shear experiments, cells grown to a >90% confluence were exposed to physiological levels of LSS (5 to 20 dyne/cm2) for 12 to 36 hours using a cone and plate shear apparatus. Gene expressions were analyzed by western blotting.

[Results]

Depletion of mitochondrial integrity was directly associated with increase in endothelial activation/dysfunction. The expressions of mitochondrial biogenesis regulator genes, such as SIRT1, PGC-1α, and TFAM, and the mitochondrial contents were significantly increased after treatment with both resveratrol and high-flow LSS for 12 hours. However, supplementation of resveratrol to high-flow LSS for a prolonged duration had no synergistic effect on the levels of mitochondrial biogenesis regulator gene expressions and mitochondrial content compared to the LSS treatment alone.

[Conclusion]

The present study demonstrated that the supplementation of resveratrol to high-flow LSS has no synergistic effects on enhancing mitochondrial integrity in human vascular endothelial cells.

Platelets release proinflammatory microparticles in anti-neutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVES

The biological functions of the platelets contributing to ANCA-associated vasculitis (AAV) are largely unclear. The current study aimed to investigate the potential role of platelet-derived microparticles (PMPs) in AAV.

METHODS

In the current study, microparticles in AAV patients were analysed by flow cytometry, and PMPs were probed for relative levels of 640 bioactive proteins secreted from patients' platelets using antibody microarrays. These data were then correlated with clinical and pathological parameters.

RESULTS

PMPs were significantly increased in 69 AAV patients, predominantly MPO-ANCA positive patients in active stage compared with in remission [4406.8/μl (2135.4, 5485.0) vs 549.7/μl (350, 708.5), P < 0.0001], and 43% of microparticles in active AAV were PMPs. Compared with 15 patients in remission, highly expressed proinflammatory molecules in the microparticles from platelets in 15 AAV patients in active stage revealed that potential functions of PMPs were promotion of the effect of chemotaxis, adhesion, growth and apoptosis (all the patients for array analysis were MPO-ANCA positive). The level of PMPs had a significant association with disease activity, inflammation, and renal damage.

CONCLUSION

PMPs may serve as inflammatory propagators through their wide production of proinflammatory cytokines in AAV, potentially providing a novel therapeutic target.

Increased concentrations of platelet- and endothelial-derived microparticles in patients with myocardial infarction and reduced renal function- a descriptive study

Background

Patients with chronic kidney disease (CKD) have a high risk of recurring thrombotic events following acute myocardial infarction (AMI). Microparticles (MPs) are circulating small vesicles shed from various cells. Platelet microparticles (PMPs) reflect platelet activation and endothelial microparticles (EMPs) reflect endothelial activation or dysfunction. Both increase following AMI, and may mediate important biological effects. We hypothesized that AMI patients with CKD have further elevated PMPs and EMPs compared with non-CKD patients, despite concurrent antithrombotic treatment.

Methods

We performed a descriptive study of patients with AMI. Fasting blood samples were acquired from 47 patients on dual antiplatelet treatment. Patients were stratified by renal function: normal (H; n = 19) mean eGFR 88; moderate CKD (CKD3; n = 15) mean eGFR 47, and severe CKD (CKD4–5; n = 13) mean eGFR 20 mL/min/1.73 m².

MPs were measured by flow-cytometry and phenotyped according to size (< 1.0 μm) and expression of CD41 (GPIIb; PMPs) and CD62E (E-selectin; EMPs). In addition, expression of platelet activation markers P-selectin (CD62P) and CD40ligand (CD154) were also investigated.

Results

PMPs expressing CD40 ligand were higher in CKD4–5: 210 /μl (174–237); median and interquartile range; vs. group H; 101 /μl (71–134; p < 0.0001) and CKD 3: 142 /μl (125–187; p = 0.006). PMPs expressing P-selectin were higher in CKD4–5 compared with H, but not in CKD3. EMPs were higher in CKD4–5; 245 /μl (189–308) compared with H; 83 /μl (53–140; p < 0.0001) and CKD3; 197 /μl (120–245; p < 0.002).

Conclusions

In AMI patients, PMPs and EMPs from activated platelets and endothelial cell are further elevated in CKD patients. This indicate impaired endothelial function and higher platelet activation in CKD patients, despite concurrent antiplatelet treatment.

Platelet-Derived Microparticles: A New Index of Monitoring Platelet Activation and Inflammation in Kawasaki Disease

OBJECTIVE

To investigate the dynamic changes of platelet-derived microparticles (PDMP) in Kawasaki disease (KD) and its clinical significance and to study its relationship with intravenous immunoglobulin (IVIG) resistance, inflammatory indicators and aspirin treatment in children with KD.

METHODS

Twenty children with KD were enrolled as the experimental group, while 20 age- and gender-matched children with common febrile disease were included in the control group. Blood samples were drawn before and 7-10 d after IVIG infusion and thereafter at 1, 2, and 3 mo after the onset of KD to estimate the PDMP concentrations by enzyme linked immunosorbent assay (ELISA). C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR), procalcitonin (PCT), and cytokines [Interleukin-6 (IL-6), Tumor necrosis factor-α (TNF-α), and Soluble interleukin-2 (sIL-2R)] were also measured.

RESULTS

The level of PDMP in KD children before IVIG was significantly higher than that in controls (P < 0.0001). The PDMP level in KD children decreased significantly at 7 to 10 d after IVIG (P < 0.0001) and then decreased to the lowest level in the course of 1 to 2 mo. Some children's PDMP level rebounded in the course of 3 mo (P = 0.047). In addition, the mean level of PDMP in IVIG-resistant children was higher than that in IVIG-effective children; however, there was no significant difference between the two groups (P = 0.1945). Furthermore, PDMP was positively correlated with hs-CRP, IL-6, and sIL-2R levels, but no correlation was observed with ESR, PCT, and TNF-α levels.

CONCLUSIONS

PDMP can be used as an index to monitor inflammation in children at the acute stage of KD. And the duration of platelet activation in KD is individualized.

Effects of acute insulin-induced hypoglycaemia on endothelial microparticles in adults with and without type 2 diabetes

AIMS

To assess whether endothelial microparticles (EMPs), novel surrogate markers of endothelial injury and dysfunction, are differentially produced in response to acute insulin-induced hypoglycaemia in adults with and without type 2 diabetes.

MATERIALS AND METHODS

A prospective, parallel study was conducted in individuals with type 2 diabetes (n = 23) and controls (n = 22). Hypoglycaemia (<2.2 mmoL/L: <40 mg/dL) was achieved by intravenous infusion of soluble insulin. Blood samples were collected at baseline and at 0, 30, 60, 120, 240 minutes and 24 hours after hypoglycaemia and analysed for CD31⁺ (platelet endothelial cell adhesion molecule-1), CD54⁺ (intercellular adhesion molecule 1), CD62-E⁺ (E-selectin), CD105⁺ (endoglin), CD106⁺ (vascular cell adhesion molecule 1) and CD142⁺ (tissue factor) EMPs by flow cytometry. The peak elevations (% rise from 0 minutes after hypoglycaemia) in EMP within 240 minutes after insulin-induced hypoglycaemia were modelled using a regression model, with adjustment for relevant covariates. All EMPs were expressed as percentage from 0 minutes hypoglycaemia for each time point and total areas under the curve (AUC_0min-24h ) were calculated.

RESULTS

Following insulin-induced hypoglycaemia, levels of circulating EMPs were maximal at 240 minutes (P < 0.001) and returned to baseline values within 24 hours for both groups. The peak elevations (% rise from 0 minutes following hypoglycaemia) seen in CD31⁺ , CD54⁺ , CD62-E⁺ , CD105⁺ and CD142⁺ EMPs within 240 minutes were associated with diabetes status after adjustments for all relevant covariates. Individuals with type 2 diabetes showed increased CD31⁺ EMPs AUC_0min-24h (P = 0.014) and CD105⁺ EMPs AUC_0min-24h (P = 0.006) compared with controls, but there were no differences for CD54⁺ (P = 0.91), CD62-E⁺ (P = 0.14), CD106⁺ (P = 0.36) or CD142⁺ (P = 0.77) EMPs AUC_0min-24h .

CONCLUSIONS

The associations between peak elevations within 240 minutes after insulin-induced hypoglycaemia for CD31⁺ , CD54⁺ , CD62-E⁺ , CD105⁺ and CD142⁺ and diabetes status indicate that the assessment of a panel of EMPs within this timeframe would identify a hypoglycaemic event in this population. The greater overall responses over time (AUCs) for apoptosis-induced CD31⁺ and CD105⁺ EMPs suggest that hypoglycaemia exerts greater endothelial stress in type 2 diabetes.

Short-term exercise training reduces glycaemic variability and lowers circulating endothelial microparticles in overweight and obese women at elevated risk of type 2 diabetes

Exercise is recognized as a frontline therapy for the prevention and treatment of type 2 diabetes (T2D) but the optimal type of exercise is not yet determined. We compared the effects of high-intensity interval training (HIIT) with moderate-intensity continuous training (MICT) for improvement of continuous glucose monitoring (CGM)-derived markers of glycaemic variability, and biomarkers of endothelial cell damage (CD31+ and CD62+ endothelial microparticles (EMPs)) within a population at elevated risk of developing T2D. Fifteen inactive overweight or obese women were randomized to 2 weeks (10-sessions) of progressive HIIT (n = 8, 4-10X 1-min @ ∼90% peak heart rate, 1-min rest periods) or MICT (n = 7, 20-50 min of continuous activity at ∼65% peak heart rate). Prior and three days post-training, fasting blood samples were collected. Both HIIT and MICT improved glycaemic variability as measured by CGM standard deviation (HIIT: 0.82 ± 0.39 vs. 0.72 ± 0.33 mmol/L; MICT: 0.82 ± 0.19 vs. 0.62 ± 0.16 mmol/L, pre vs. post) and mean amplitude of glycaemic excursions (MAGE; HIIT: 1.98 ± 0.81 vs. 1.41 ± 0.90; MICT; 1.98 ± 0.43 vs. 1.65 ± 0.48, pre vs. post) with no difference between groups. CD62+ EMPs were lower following HIIT (187.7 ± 65 vs. 174.9 ± 55, pre vs. post) and MICT (170 ± 60 vs. 160.3 ± 59, pre vs. post) with no difference between groups. There was no change in 24-h mean glucose or CD31+ EMPs. Two weeks of both HIIT or MICT similarly decreased glycaemic variability and CD62+ EMPs in overweight/obese women at elevated risk of T2D.

Sodium Intake, Circulating Microvesicles and Cardiovascular Outcomes in Type 2 Diabetes

There is ongoing debate surrounding the complex relationship between dietary sodium intake and cardiovascular morbidity and mortality. The existing literature consists largely of observational studies that have demonstrated positive, negative, U-/J-shaped or unclear associations between sodium intake and cardiovascular outcomes. Our group and others have previously demonstrated an inverse relationship between dietary sodium intake and cardiovascular outcomes in people with type 2 diabetes. Increased activity of the renin-angiotensin-aldosterone system and sympathetic nervous system is postulated to contribute to these paradoxical findings through endothelial dysfunction, a precursor to the development of cardiovascular disease. Microvesicles are submicron (0.1 - 1.0μm) vesicles that form during cellular activation, injury or death with endothelial microvesicles being recognized markers of endothelial dysfunction. They are pathologically elevated in a variety of vascular-related conditions including type 2 diabetes. Lower habitual sodium intake in type 2 diabetes has been associated with higher pro-coagulant platelet microvesicles levels but not with endothelial microvesicles. Research utilizing endothelial microvesicles to evaluate the mechanistic relationship between dietary sodium intake and adverse cardiovascular outcomes in type 2 diabetes remains scarce.

Microvesicle detection by a reduced graphene oxide field-effect transistor biosensor based on a membrane biotinylation strategy

A reduced graphene oxide field-effect transistor biosensor for the detection of microvesicles by using a membrane biotinylation strategy.

Protein Biomarker Discovery Using Human Blood Plasma Microparticles

Cells shed into the extracellular space a population of membranous vesicles of plasma membrane origin called microparticles (MP). Given the fact that MP are abundantly present in body fluids including plasma, rich in cell-type or disease-specific proteins and formed in conditions of stress and injury, they have been extensively investigated as biomarkers in various diseases. With the advancement in the mass spectrometry-based proteome analysis, the knowledge of the protein composition of plasma MP (PMP) has been intensively expanded, which aids the discovery of novel diagnostic target proteins. However, the lack of standardized and accurate protocols for PMP isolation limits the implementation of PMP as biomarkers in clinical settings. Here, we describe in detail a robust protocol for PMP isolation from human blood plasma via ultracentrifugation followed by label-free quantitative proteome analysis of PMP.

Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology

The renin-angiotensin-aldosterone system plays crucial roles in cardiovascular physiology and pathophysiology. However, many of the signaling mechanisms have been unclear. The angiotensin II (ANG II) type 1 receptor (AT₁R) is believed to mediate most functions of ANG II in the system. AT₁R utilizes various signal transduction cascades causing hypertension, cardiovascular remodeling, and end organ damage. Moreover, functional cross-talk between AT₁R signaling pathways and other signaling pathways have been recognized. Accumulating evidence reveals the complexity of ANG II signal transduction in pathophysiology of the vasculature, heart, kidney, and brain, as well as several pathophysiological features, including inflammation, metabolic dysfunction, and aging. In this review, we provide a comprehensive update of the ANG II receptor signaling events and their functional significances for potential translation into therapeutic strategies. AT₁R remains central to the system in mediating physiological and pathophysiological functions of ANG II, and participation of specific signaling pathways becomes much clearer. There are still certain limitations and many controversies, and several noteworthy new concepts require further support. However, it is expected that rigorous translational research of the ANG II signaling pathways including those in large animals and humans will contribute to establishing effective new therapies against various diseases.

Exosome: Function and Role in Cancer Metastasis and Drug Resistance

As a kind of nanometric lipidic vesicles, exosomes have been presumed to play a leading role in the regulation of tumor microenvironment through exosomes-mediated transfer of proteins and genetic materials. Tumor-derived exosomes are recognized as a critical determinant of the tumor progression. Intriguingly, some current observations have identified that exosomes are essential for several intercellular exchanges of proteins, messenger RNAs, noncoding RNAs (including long noncoding RNAs and microRNAs) as well as to the process of cancer metastasis and drug resistance. Herein, we review the role of exosomes and their molecular cargos in cancer invasion and metastasis, summarize how they interact with antitumor agents, and highlight their translational implications.

Large-scale, cross-flow based isolation of highly pure and endocytosis-competent extracellular vesicles

Isolation of extracellular vesicles (EVs) from cell culture supernatant or plasma can be accomplished in a variety of ways. Common measures to quantify relative success are: concentration of the EVs, purity from non-EVs associated protein, size homogeneity and functionality of the final product. Here, we present an industrial-scale workflow for isolating highly pure and functional EVs using cross-flow based filtration coupled with high-molecular weight Capto Core size exclusion. Through this combination, EVs loss is kept to a minimum. It outperforms other isolation procedures based on a number of biochemical and biophysical assays. Moreover, EVs isolated through this method can be further concentrated down or directly immunopurified to obtain discreet populations of EVs. From our results, we propose that cross-flow/Capto Core isolation is a robust method of purifying highly concentrated, homogenous, and functionally active EVs from industrial-scale input volumes with few contaminants relative to other methods.

The Inflammatory Response to Ventricular Assist Devices

The therapeutic use of ventricular assist devices (VADs) for end-stage heart failure (HF) patients who are ineligible for transplant has increased steadily in the last decade. In parallel, improvements in VAD design have reduced device size, cost, and device-related complications. These complications include infection and thrombosis which share underpinning contribution from the inflammatory response and remain common risks from VAD implantation. An added and underappreciated difficulty in designing a VAD that supports heart function and aids the repair of damaged myocardium is that different types of HF are accompanied by different inflammatory profiles that can affect the response to the implanted device. Circulating inflammatory markers and changes in leukocyte phenotypes receive much attention as biomarkers for mortality and disease progression. However, they are seldom used to monitor progress during and outcomes from VAD therapy or during the design phase for new devices. Even the partial reversal of heart damage associated with heart failure is a desirable outcome from VAD use. Therefore, improved understanding of the interplay between VADs and the recipient's inflammatory response would potentially increase their uptake, improve patient lives, and fuel research related to other blood-contacting medical devices. Here we provide a review of what is currently known about inflammation in heart failure and how this inflammatory profile is altered in heart failure patients receiving VAD therapy.

The relationship between habitual dietary sodium intake and RAAS blockade on circulating microparticle levels in type two diabetes

OBJECTIVE

Low sodium intake is paradoxically associated with adverse cardiovascular outcomes in individuals with type 2 diabetes mellitus (T2D), possibly from renin-angiotensin-aldosterone system (RAAS) activation, leading to endothelial dysfunction. In the present study, we investigated the associations between habitual sodium intake and RAAS blockade on endothelial function by measuring circulating microparticles (MPs) in individuals with T2D.

METHODS

We conducted a prospective, cross-sectional study in 74 individuals with T2D. Habitual dietary sodium intake was estimated by using the mean of three corrected 24-h urine sodium excretion measurements (24hUNa). MP subtypes in platelet-free plasma were quantitated using flow cytometry.

RESULTS

No associations between 24hUNa with levels of endothelial MPs were observed. Instead, a trend toward higher diabetes related CD36+/CD235a+ MP levels was associated with lower 24hUNa (rho = -0.23, P=0.05). When stratified according to tertiles of 24hUNa, platelet-derived CD42b+/CD41+ and CD42+/CD41+/Annexin V+ MPs were higher in the lowest tertile (24hUNa < 157 mmol/24 h) (P=0.02 respectively). Despite RAAS blockade being associated with lower levels of most MP subsets, it was not associated with lower MPs, in the setting of low sodium intake.

CONCLUSION

Lower sodium intake is associated with higher circulating procoagulant MPs, but not with evidence of endothelial dysfunction in individuals with T2D.

Acute effects of haemodialysis on circulating microparticles

Background

Microparticles (MPs) are small cell membrane-derived vesicles regarded as both biomarkers and mediators of biological effects. Elevated levels of MPs have previously been associated with endothelial dysfunction and predict cardiovascular death in patients with end-stage renal disease. The objective of this study was to measure change in MP concentrations in contemporary haemodialysis (HD).

Methods

Blood was sampled from 20 consecutive HD patients before and 1 h into the HD session. MPs were measured by flow cytometry and phenotyped based on surface markers.

Results

Concentrations of platelet (CD41⁺) (P = 0.039), endothelial (CD62E⁺) (P = 0.004) and monocyte-derived MPs (CD14⁺) (P < 0.001) significantly increased during HD. Similarly, endothelial- (P = 0.007) and monocyte-derived MPs (P = 0.001) expressing tissue factor (TF) significantly increased as well as MPs expressing Klotho (P = 0.003) and receptor for advanced glycation end products (RAGE) (P = 0.009). Furthermore, MPs expressing platelet activation markers P-selectin (P = 0.009) and CD40L (P = 0.045) also significantly increased. The increase of endothelial (P = 0.034), monocyte (P = 0.014) and RAGE⁺ MPs (P = 0.032) as well as TF⁺ platelet-derived MPs (P = 0.043) was significantly higher in patients treated with low-flux compared with high-flux dialysers.

Conclusion

Dialysis triggers release of MPs of various origins with marked differences between high-flux and low-flux dialysers. The MPs carry surface molecules that could possibly influence coagulation, inflammation, oxidative stress and endothelial dysfunction. The clinical impact of these findings remains to be established in future studies.

BLTR1 and CD36 Expressing Microvesicles in Atherosclerotic Patients and Healthy Individuals

Aims: Monocytes/macrophages play a crucial role in the development, progression, and complication of atherosclerosis. In particular, foam cell formation driven by CD36 mediated internalization of oxLDL leads to activation of monocytes and subsequent release of microvesicles (MVs) derived from monocytes (MMVs). Further, pro-inflammatory leukotriene B4 (LTB4) derived from arachidonic acid promotes atherosclerosis through the high-affinity receptor BLTR1. Thus, we aimed to investigate the correlation between different MMV phenotypes (CD14⁺ MVs) on the one hand, and arachidonic acid and eicosapentaenoic acid contents in different compartments including atherosclerotic plaques, plasma, and granulocytes on the other.

Methods and Results: Samples from patients with femoral atherosclerosis and healthy controls were analyzed on an Apogee A60 Micro-PLUS flow cytometer. Platelet-poor plasma was labeled with lactadherin-FITC, anti-CD14-APC, anti-CD36-PE, and anti-BLTR1-AF700. Eicosapentaenoic acid and arachidonic acid content in different compartments in patients were analyzed using gas chromatography. Compared to controls, patients had lower levels of BLTR1⁺ MVs (p = 0.007), CD14⁺BLTR1⁺ MVs (p = 0.007), and CD14⁺BLTR1⁺CD36⁺ MVs (p = 0.001). Further, in patients CD14⁺ MVs and CD14⁺CD36⁺ MVs correlated inversely with arachidonic acid in granulocytes (r = −0.302, p = 0.039 and r = −0.322, p = 0.028, respectively). Moreover, CD14⁺CD36⁺ MVs correlated inversely with arachidonic acid in plasma phospholipids in patients (r = −0.315, p = 0.029), and positively with triglyceride in both patients (r = 0.33, p = 0.019) and controls (r = 0.46, p = 0.022).

Conclusion: This is the first study of its kind and thus the results are explorative and only indicative. BLTR1⁺ MVs and CD14⁺CD36⁺ MVs has potential as markers of atherosclerosis pathophysiology, but this needs further investigation.

Elevated levels of platelet- and red cell-derived extracellular vesicles in transfusion-dependent β-thalassemia/HbE patients with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a serious complication in β-thalassemia. The mechanism of PAH development is believed to be through chronic platelet activation and red cell (RBC) membrane abnormality contributing to a hypercoagulable state and thrombosis, which consequently leads to the development of PAH. Extracellular vesicles (EVs) shed from the plasma membrane of platelets and RBCs are found to be associated with thrombotic risk. This study aimed to investigate the involvement of phosphatidylserine (PS)-bearing cells and EVs in accelerating the progression of the hypercoagulable state in transfusion-dependent thalassemia (TDT) patients. Fresh whole blood samples from splenectomized TDT-β-thalassemia/HbE patients (11 with PAH and 14 without PAH) and 15 normal subjects were analyzed for platelet activation by measuring P-selectin expression using flow cytometry and the number of dense granular using an electron microscope. The amounts of PS-bearing RBCs, large RBC-EVs, platelets, and medium EVs were determined by flow cytometry. Platelet activation in PAH patients was not significantly different from other groups; however, the amounts of PS-bearing large RBC-EVs, platelets, and medium platelet-derived EVs were significantly increased in PAH patients as compared to normal subjects, but they were not different from patients without PAH. This could be affected by antiplatelet therapy that reduced the levels of platelet activation and the amount of PS-bearing cells, including EVs, in PAH patients as well as in patients without PAH.

Significant association of anti-platelet factor 4/heparin antibody with cardiovascular disease in hemodialysis patients: a longitudinal 7-year study

BACKGROUND

Hemodialysis patients have a high incidence of anti-platelet factor 4/heparin antibody (PF4-H Ab) and are at a high risk of cardiovascular disease. This study determines the association between PF4-H Ab and cardiovascular events including coronary artery disease (CAD), ischemic stroke (IS), and native arteriovenous fistula thrombosis (AVFT), in a longitudinal 7-year follow-up.

PATIENTS AND METHODS

84 hemodialysis patients were enrolled. Data collection included chart reviews and assessments of laboratory records. PF4-H Ab was evaluated by ELISA and a titer ≥ 0.4 was defined to have PF4-H Ab.

RESULTS

30 patients were PF4-H Ab positive, 30 patients had CAD, 29 patients had IS, and 43 patients had AVFT. In Cox proportional hazard regression analysis, PF4-H Ab (HR 2.72, p = 0.01) was a significant risk factor for CAD. Age (HR 1.06, p = 0.003), PF4-H Ab (HR 4.53, p < 0.001), 7-year averaged serum phosphate levels (HR 0.53, p = 0.012), and 7-year averaged blood platelet count (HR 1.01, p = 0.029) were risk factors for IS. Age (HR 1.03, p = 0.047), PF4-H Ab (HR 3.57, p < 0.001), and 7-year averaged serum triglyceride levels (HR 1.01, p = 0.005) were risk factors for AVFT. In PF4-H Ab-positive groups, thrombocytopenia was not associated with CAD, IS, and AVFT by Fisher's test analysis.

CONCLUSION

This study reveals that PF4-H Ab is a risk factor for developing CAD, IS, and AVFT among hemodialysis patients.

Mononuclear-cell-derived microparticles attenuate endothelial inflammation by transfer of miR-142-3p in a CD39 dependent manner

Plasma microparticles (MP) bear functional active ectonucleotidases of the CD39 family with implications in vascular inflammation. MP appear to be able to fuse with cells and transfer genetic information. Here, we tested whether levels of different immunomodulatory microRNAs (miRs) in plasma MP are modulated by CD39 after experimental hepatectomy. We further investigated whether horizontal transfer of miR-142-3p between mononuclear (MNC) and endothelial cells via MP is regulated by purinergic signaling. Partial hepatectomy was performed in C57BL/6 wild type and Cd39 null mice. MP were collected via ultracentrifugation. MNC were stimulated with nucleotides and nucleosides, in vitro, and tested for miR-142-3p levels. Fusion of MNC-derived MP and endothelial cells with subsequent transfer of miR-142-3p was imaged by flow cytometry and confocal microscopy. Endothelial inflammation and apoptosis were quantified after transfection with miR-142-3p. Significantly lower miR-142-3p levels were observed in plasma MP of Cd39 null mice after partial hepatectomy, when compared to C57BL/6 wild types (p < 0.05). In contrast to extracellular nucleotides, anti-inflammatory adenosine significantly increased miR-142-3p levels in MNC-derived MP, in vitro (p < 0.05). MNC-derived MP are able to transfer miR-142-3p to endothelial cells by fusion. Transfection of endothelial cells with miR-142-3p decreased TNF-α levels (p < 0.05) and endothelial apoptosis (p < 0.05). MiR-142-3p levels in MNC-derived MP are modulated by nucleoside signaling and might reflect compensatory responses in vascular inflammation. Our data suggest the transfer of genetic information via shed MP as a putative mechanism of intercellular communication-with implications in organ regeneration.

Circulating microparticles in patients after ischemic stroke: a systematic review and meta-analysis

Microparticles (MPs), a class of cell products with biological activities, have been found to participate in a series of vascular activities. The aim of this article is to investigate the changes in the concentrations of MPs after ischemic stroke by meta-analysis. According to pre-established criteria, a strict screening of articles was performed through the Medline and Embase databases. Subsequently, the included studies were subjected to quality assessment and data extraction. Finally, a meta-analysis was performed on seven major outcomes from 985 noncerebrovascular disease controls and 988 ischemic stroke patients. The pooled concentrations of total MPs (TMPs), endotheliocyte-derived MPs (EMPs), platelet-derived MPs (PMPs), erythrocyte-derived MPs (RMPs), leukocyte-derived MPs (LMPs), and monocyte-derived MPs (MMPs) were significantly increased in the ischemic stroke patients compared to the noncerebrovascular disease controls, with the results as follows: TMPs [standardized mean difference (SMD), 1.12; 95% confidence interval (CI), 0.26-1.97; p=0.01], EMPs (SMD, 0.90; 95% CI, 0.67-1.13; p<0.00001), PMPs (SMD, 1.15; 95% CI, 0.69-1.60; p<0.00001), RMPs (SMD, 1.14; 95% CI, 0.57-1.71; p<0.0001), LMPs (SMD, 1.42; 95% CI, 0.74-2.10; p<0.0001), and MMPs (SMD, 1.09; 95% CI, 0.59-1.60; p<0.0001). However, the pooled concentration of lymphocyte-derived MPs (LyMPs) demonstrated no significant difference between the patients and the controls (SMD, 0.22; 95% CI, -0.19 to 0.63; p=0.29). The available data indicated that the circulating MPs, except for LyMPs, play an important role in the development and prognosis of ischemic stroke.

Effect of methamphetamine exposure on the plasma levels of endothelial-derived microparticles

BACKGROUND

Methamphetamine (Meth), a neurotoxin, induces inflammation, oxidative stress, and triggers endothelial dysfunction and cardiovascular disease which is the second cause of death among individuals with Meth-use disorder. Oxidative stress and inflammation trigger the microparticle (MP) release. These are extracellular vesicles extracted from cell surface and identified in biological fluids. MP levels alter during pathological conditions, suggesting its potential biomarker role. In this respect, we designed the present experiment to investigate the effects of Meth on the plasma level of the endothelial-derived microparticle (EMP).

METHODS

Animals received Meth (4 mg/kg i.p.) for 1, 7 and 14 days and then, the plasma level of EMPs was evaluated, using cell surface markers, including AnnexinV, CD144, CD31, CD41a antigens with the flow cytometry method. The biochemical indices and locomotor activity were also assessed in a rat model.

RESULTS

Meth increased locomotor activity (Meth-1, 277.12 ± 20.17; Meth-7, 262.25 ± 11.95; Meth-14, 265.75 ± 14.75), inflammatory and oxidative indices as evidenced by rising of the C-reactive protein (Meth-7, 39.4 ± 1.24; Meth-14, 38.58 ± 2.19, vs 8.65 ± 0.45, mg/L) and malondialdehyde (Meth-7, 9.74 ± 1.38; Meth-14, 14.6 ± 1.45, vs 4.43 ± 0.32 nmol/L) plasma levels. We also found that Meth triggered endothelial injury, as demonstrated by elevated levels of EMP (Meth-7, 4.77 ± 0.22; Meth-14, 5.91 ± 0.34, % total events/mL) compared with control group.

CONCLUSION

Our data showed that Meth exposure stimulates inflammatory and oxidative pathways and facilitates the EMPs shedding. Measuring the level of EMPs might be applied as a potential diagnostic index to monitor the endothelial dysfunction in substance-use disorders.

Increased circulating endothelial microparticles in children with FMF

OBJECTIVE

Endothelial microparticles (EMPs) are considered as markers of endothelial dysfunction. In this study, we aimed to examine whether there is endothelial dysfunction in children with familial Mediterranean fever (FMF), hypothesizing that endothelial dysfunction would be present especially with acute-phase response in the active period of the disease.

METHODS

This cross-sectional study included 65 FMF patients (41 attack free, 24 attack period) and 35 healthy controls. Circulating EMPs, serum amyloid A (SAA), and other inflammation markers were measured in all groups. Circulating EMPs were measured using flow cytometry. Study groups were compared for circulating EMP and inflammatory markers. The relationship between EMPs and the activation of the disease was evaluated.

RESULTS

The levels of CD144⁺ and CD146⁺ EMPs in the FMF attack period group were significantly higher than those of the control group (p < 0.05). The levels of inflammation markers in the attack period group were significantly higher than those of the control and attack-free groups (p < 0.05). In the FMF attack group, the CD144⁺ and CD146⁺ EMP were significantly correlated with CRP.

CONCLUSIONS

Our results suggest that endothelial damage is present especially in the active period of the disease in children with FMF. The endothelial dysfunction becomes an overt parallel with inflammation.

HMGB1/IL-1β complexes in plasma microvesicles modulate immune responses to burn injury

Modulating immune responses to sepsis and trauma remain one of the most difficult challenges in modern medicine. Large burn injuries (LBI) are a severe form of trauma associated with sepsis, immune impairment, and mortality. Immune dysfunction after LBI is complex, involving both enhanced and impaired immune activation. The release of Damage-Associated Molecular Patterns (DAMPs), such as HMGB1, and cytokines (e.g. IL-1β) creates an environment of immune dysfunction often leading to end organ failure and death. Both HMGB1 and IL-1β have been found to play critical roles in sepsis and post-burn immune dysfunction. HMGB1 and IL-1β have been shown previously to form potent complexes in vitro. We recently identified the presence of HMGB1/IL-1β heterocomplexes in human tissue. We now find HMGB1/IL-1β complexes in human and mouse plasma, and identify a synergistic role of HMGB1/IL-1β complexes in post-burn immune dysfunction. In both humans and mice, we found that HMGB1 was enriched in plasma microvesicles (MVs) after LBI. HMGB1 was found form complexes with IL-1β. Using flow cytometry of mouse plasma MVs, we identified an increase in an HMGB1+/IL-1β+ MVs. Using co-IP, HMGB1 was found to bind the pro-form of IL-1β in mouse and human plasma. Pro-IL-1β, which is traditionally considered inactive, became active when complexed with HMGB1. Human THP-1 monocytes treated with HMGB1-pro-IL-1β complexes showed increased transcription of LBI associated cytokines IL-6 and IFNβ along with suppression of iNOS, mimicking findings associated with LBI. These findings identify that HMGB1/IL-1β complexes released after burn injuries can modulate immune responses, and microvesicles are identified as a novel reservoir for these immune mediators. These complexes might serve as novel immune targets for the treatment of systemic immune responses due to LBI or other causes of sepsis.

Non-Proximal Renal Tubule-Derived Urinary Exosomal miR-200b as a Biomarker of Renal Fibrosis

BACKGROUND

Renal fibrosis is a common outcome of nearly all kinds of chronic kidney disease (CKD) and eventually progresses to end-stage renal disease. The identification of an optimal biomarker of renal fibrosis to replace the invasive renal biopsy will have important clinical implications.

METHODS

We isolated urinary exosomes from 50 participants and examined the exosomal protein content and particle number in 38 CKD patients with different degrees of renal fibrosis and in 12 normal individuals. We examined the levels of exosomal microRNAs (miRNAs), namely, miR-200a, miR-200b, miR-200c, miR-141, miR-429, miR-29a, miR-29b, miR-29c, miR-192, and miR-21, by sorting the exosomes and comparing the levels of proximal tubular, non-proximal tubular, and total exosomal miR-200b.

RESULTS

The exosome content was higher in the CKD group, but no differences were evident among the mild, moderate, and severe fibrosis groups. Among the 10 exosomal miRNAs, miR-200b was lower in the CKD group than in the normal group and decreased more significantly with fibrosis progression as well as in IgA nephropathy and diabetic kidney disease. CD13+ CD63+ exosomes constituted 18.6% of all urinary exosomes. Sorting the proximal tubular exosomes with the CD13 protein marker revealed that miR-200b in the CD13+ group was extremely low; however, the result was significantly different in the CD13- group but not in the CD13+ group. The magnitude of the decline was greater in the CD13- groups than in the non-sorted whole groups between the fibrosis and normal patients.

CONCLUSIONS

Non-proximal renal tubule-derived urinary exosomal miR-200b is a biomarker of renal fibrosis. Exosomes can be used as a liquid biopsy and may replace the traditional invasive renal biopsy in the diagnosis of renal fibrosis.

Microparticles as new markers of cardiovascular risk in diabetes and beyond

The term microparticle (MP) identifies a heterogeneous population of vesicles playing a relevant role in the pathogenesis of vascular diseases, cancer and metabolic diseases such as diabetes mellitus. MPs are released by virtually all cell types by shedding during cell growth, proliferation, activation, apoptosis or senescence processes. MPs, in particular platelet- and endothelial-derived MPs (PMPs and EMPs), are increased in a wide range of thrombotic disorders, with an interesting relationship between their levels and disease pathophysiology, activity or progression. EMP plasma levels have been associated with several cardiovascular diseases and risk factors. PMPs are also shown to be involved in the progressive formation of atherosclerotic plaque and development of arterial thrombosis, especially in diabetic patients. Indeed, diabetes is characterised by an increased procoagulant state and by a hyperreactive platelet phenotype, with enhanced adhesion, aggregation, and activation. Elevated MP levels, such as TF+ MPs, have been shown to be one of the procoagulant determinants in patients with type 2 diabetes mellitus. Atherosclerotic plaque constitutes an opulent source of sequestered MPs, called “plaque” MPs. Otherwise, circulating MPs represent a TF reservoir, named “blood-borne” TF, challenging the dogma that TF is a constitutive protein expressed in minute amounts. “Blood-borne” TF is mainly harboured by PMPs, and it can be trapped within the developing thrombus. MP detection and enumeration by polychromatic flow cytometry (PFC) have opened interesting perspectives in clinical settings, particularly for the evaluation of MP numbers and phenotypes as independent marker of cardiovascular risk, disease and outcome in diabetic patients.

Podocyte-derived microparticles promote proximal tubule fibrotic signaling via p38 MAPK and CD36

Tubulointerstitial fibrosis is a hallmark of advanced diabetic kidney disease that is linked to a decline in renal function, however the pathogenic mechanisms are poorly understood. Microparticles (MPs) are 100–1000 nm vesicles shed from injured cells that are implicated in intercellular signalling. Our lab recently observed the formation of MPs from podocytes and their release into urine of animal models of type 1 and 2 diabetes and in humans with type 1 diabetes. The purpose of the present study was to examine the role of podocyte MPs in tubular epithelial cell fibrotic responses. MPs were isolated from the media of differentiated, untreated human podocytes (hPODs) and administered to cultured human proximal tubule epithelial cells (PTECs). Treatment with podocyte MPs increased p38 and Smad3 phosphorylation and expression of the extracellular matrix (ECM) proteins fibronectin and collagen type IV. MP-induced responses were attenuated by co-treatment with the p38 inhibitor SB202190. A transforming growth factor beta (TGF-β) receptor inhibitor (LY2109761) blocked MP-induced Smad3 phosphorylation and ECM protein expression but not p38 phosphorylation suggesting that these responses occurred downstream of p38. Finally, blockade of the class B scavenger receptor CD36 completely abrogated MP-mediated p38 phosphorylation, downstream Smad3 activation and fibronectin/collagen type IV induction. Taken together our results suggest that podocyte MPs interact with proximal tubule cells and induce pro-fibrotic responses. Such interactions may contribute to the development of tubular fibrosis in glomerular disease.

Plasma microparticles in Alzheimer's disease: The role of vascular dysfunction

Cerebrovascular lesions, a potent stimulus for endothelial cell activation, trigger cognitive and degenerative changes and contribute to pathology of Alzheimer's disease (AD). Circulating microparticles (MPs) are actively involved in the pathogenesis of AD and cerebrovascular diseases, which share common vascular risk factors. We examined the plasma changes of endothelial MPs (EMPs) and platelet MPs (PMPs) in AD patients with vascular risk factors. The plasma Annexin V⁺ CD 41a^- CD144⁺ EMPs and Annexin V⁺ CD41a⁺ CD144^- PMPs of 37 patients with AD, with or without vascular risk factors (hypertension, diabetes, dyslipidemia, stroke, coronary artery disease, and smoking), and 10 age-matched controls were quantified by flow cytometry. Pearson correlation analysis used to evaluate the linear relationship between variables. Significantly higher plasma levels of EMPs were observed in AD patients with vascular risk factors as compared to the patients without vascular risk factors [Mean Difference (MD): 2587.80, 95% confidence interval (CI) 770.30-4404.80], and control subjects (MD: 4990.60, 95% CI, 3054.40-6926.79). Significant correlations were found between circulating EMPs, total MPs, and PMPs. There were no significant correlations between plasma levels of EMPs/ PMPs, and cognitive decline indices. Circulating EMP levels are influenced by AD disease status, and plasma levels of MPs and PMPs are associated with vascular risk factors in patients with AD. EMP phenotyping, as cellular biomarkers of vascular injury/dysfunction, and their effects on cerebral perfusion, and cognitive decline should be further investigated. Graphical abstract Vascular endothelial cell activation results in release of endothelial-derived microparticles (EMPs), which contributing to vascular dysfunction and cognitive decline.

Physiologic Impact of Circulating RBC Microparticles upon Blood-Vascular Interactions

Here, we review current data elucidating the role of red blood cell derived microparticles (RMPs) in normal vascular physiology and disease progression. Microparticles (MPs) are submicron-size, membrane-encapsulated vesicles derived from various parent cell types. MPs are produced in response to numerous stimuli that promote a sequence of cytoskeletal and membrane phospholipid changes and resulting MP genesis. MPs were originally considered as potential biomarkers for multiple disease processes and more recently are recognized to have pleiotropic biological effects, most notably in: promotion of coagulation, production and handling of reactive oxygen species, immune modulation, angiogenesis, and in initiating apoptosis. RMPs, specifically, form normally during RBC maturation in response to injury during circulation, and are copiously produced during processing and storage for transfusion. Notably, several factors during RBC storage are known to trigger RMP production, including: increased intracellular calcium, increased potassium leakage, and energy failure with ATP depletion. Of note, RMP composition differs markedly from that of intact RBCs and the nature/composition of RMP components are affected by the specific circumstances of RMP genesis. Described RMP bioactivities include: promotion of coagulation, immune modulation, and promotion of endothelial adhesion as well as influence upon vasoregulation via influence upon nitric oxide (NO) bioavailability. Of particular relevance, RMPs scavenge NO more avidly than do intact RBCs; this physiology has been proposed to contribute to the impaired oxygen delivery homeostasis that may be observed following transfusion. In summary, RMPs are submicron particles released from RBCs, with demonstrated vasoactive properties that appear to disturb oxygen delivery homeostasis. The clinical impact of RMPs in normal and patho-physiology and in transfusion recipients is an area of continued investigation.

Endothelial cell-derived microvesicles: potential mediators and biomarkers of pathologic processes

This review focuses on the formation, composition and function of endothelial microvesicles (MV), often called microparticles (MP). MV release is a controlled event and is considered a hallmark of cellular activation or alteration. MV may affect the function of target cells through surface interaction and receptor activation, cellular fusion and the delivery of intravesicular cargo. Endothelial MV are released as a consequence of endothelial activation during inflammation and have been described to affect hemostasis, various aspects of inflammatory reaction, vessel formation, apoptosis and cell survival, endothelial cell differentiation and function. Recent data suggest the potential use of MV in diagnostics, assessment of severity and prediction of outcomes in inflammatory diseases and their utilization as targets, mediators and vectors in therapy.

Review of the Association between Splenectomy and Chronic Thromboembolic Pulmonary Hypertension

Recent evidence suggests that there may be a link between splenectomy and the later development of pulmonary hypertension, in particular World Health Organization group IV pulmonary hypertension (chronic thromboembolic pulmonary hypertension). Epidemiological studies have demonstrated an odds ratio as high as 18 for the development of chronic thromboembolic pulmonary hypertension after splenectomy in comparison with matched control subjects who have not undergone splenectomy. The mechanisms governing the association between removal of the spleen and the subsequent development of chronic thromboembolic pulmonary hypertension remain incompletely understood; however, recent advances in understanding of coagulation homeostasis have shed some light on this association. Splenectomy increases the risk of venous thromboembolic disease, a necessary precursor of chronic thromboembolic pulmonary hypertension, by generating a prothrombotic state. This prothrombotic state likely results from a reduction in the removal of circulating procoagulant factors from the bloodstream after splenectomy. Although much is to be learned, circulating microparticles have emerged as the most likely mediator for the development of thrombosis after splenectomy. Apparently because of a reduction in reticuloendothelial cell clearance, microparticle levels are elevated in patients after splenectomy. Elevated circulating microparticle levels have been linked to thromboembolism and pulmonary hypertension in a dose-dependent fashion. It is important for health care providers to be aware of the link between splenectomy and chronic thromboembolic pulmonary hypertension. We are optimistic that clarification of the exact mechanisms that govern this association will yield clinical guidelines and potential treatments.

Circulating microparticles levels are increased in patients with diabetic kidney disease: A case-control research

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with chronic lowgrade inflammation. Microparticles (MPs) are extracellular microvesicles released during apoptosis and cellular activation. The MP's pro-coagulant and pro-inflammatory activities are involved in endothelial dysfunction observed in T2DM patients. This study aimed to evaluate the circulating MPs profile in T2DM patients with diabetic kidney disease (DKD) and correlate it with clinical and laboratorial parameters.

METHODS

MPs derived from platelets (PMPs), leukocytes (LMPs), endothelial cells (EMPs), and expressing tissue factor (TFMPs) were measured by flow cytometry, in plasma of 39 DKD patients and 30 non-diabetic controls.

RESULTS

We observed higher PMPs, LMPs, EMPs, and TFMPs (all p<0.0001) levels in case group as compared to controls. For patients with DKD, circulating MPs levels were influenced by gender, but not by obesity status nor by T2DM onset. Fasting glucose and 25-hydroxyvitamin D levels showed correlation with circulating MPs levels in both groups.

CONCLUSIONS

These results suggest that type 2 diabetes mellitus patients with DKD presented higher circulating MPs levels - PMPs, LMPs, EMPs, and TFMPs - which correlated with metabolic alterations.

Microparticles reveal cell activation during IVF – a possible early marker of a prothrombotic state during the first trimester

Cell-derived microparticles (MPs) are known to be elevated in a number of diseases related to arterial and venous thromboembolism (VTE), such as acute myocardial infarction, VTE (deep-vein thrombosis and pulmonary embolism) and peripheral arterial disease. IVF-associated pregnancies have previously been shown to be associated with an increased incidence of VTE, mechanisms behind being unknown and sparsely studied. Our objective was to assess cell activation during IVF through analysis of MP levels and phenotype following ovarian stimulation. Thirty-one women undergoing IVF were included and blood samples were collected at down regulation of oestrogen and at high level stimulation with 10- to 100-fold increased endogenous oestrogen levels. MPs were analysed by flow cytometry and phenotyped according to size and protein expression. We found that overall phosphatidylserine positive platelet-, endothelial- and monocyte-derived MPs significantly increased following ovarian stimulation with increased levels of platelet activation markers CD40 ligand and P-selectin. Furthermore, there was an increase in endothelial-derived MPs exposing activation marker E-selectin and monocyte-derived MPs, while neutrophil-derived MPs decreased slightly. In conclusion we found a major increase in MPs and markers indicating cell activation in parallel with the profound oestrogen boost during IVF. To assess whether these changes in MPs are associated with thromboembolic events requires extended longitudinal studies.

Hypercoagulability in overweight and obese subjects who are asymptomatic for thrombotic events

The role of circulating microparticles (MP) of different origin and tissue factor (TF)-bearing in overweight and obese patients with and without metabolic syndrome is still a matter of debate. In a case-control study, the presence of hypercoagulability was evaluated in overweight and obese patients by measuring MP, thrombin generation (TG) and FVIIa-AT complexes. Twenty overweight patients (body mass index [BMI] range 25–29.9 kg/m2), 20 with I degree (30–34.9 kg/m2), 20 with II degree (35–39.9 kg/m2) and 20 with III degree obesity (≥ 40 kg/m2) were enrolled and compared to 40 age and gender-matched normal weight individuals. A significant increase in median levels of all MP subtypes was observed in the three degrees of obese patients compared to controls. Overweight patients had higher levels of annexin V-MP (AMP), endothelial-derived, leukocyte-derived and TF-bearing MP than controls. Obese patients had a significantly shorter median lag time (p< 0.05), higher median peak thrombin (p< 0.01) and increased median endogenous thrombin potential [ETP] (p< 0.001) compared to controls. Overweight subjects had significantly increased ETP compared to controls (p< 0.05). Both AMP levels and ETP were found to positively correlate with BMI, waist circumference, and inflammatory parameters. No significant increase in FVIIa-AT complex was seen in cases compared to controls. We conclude that obesity is associated with overproduction of procoagulant MP and increase TG. Interestingly, hypercoagulability is found in overweight patients free of metabolic syndrome and increases with the severity of obesity. Assessment of MP and TG may be helpful in the early characterisation of the prothrombotic state in obese patients.

Current advances in circulating inflammatory biomarkers in atherosclerosis and related cardio-cerebrovascular diseases

Atherosclerosis (AS) is a systemic chronic disease affecting both the coronary and cerebral arteries. Inflammation plays a key role in the initiation and progression of AS, and numerous inflammatory factors have been proposed as potential biomarkers. This article reviews recent research in studies on major circulating inflammatory biomarkers to identify surrogates that may reflect processes associated with AS development and the risk of AS-related vascular events, such as Von Willebrand factor, lectin-like oxidized low-density-lipoprotein receptor-1, soluble urokinase plasminogen activator receptor, regulated upon activation, normal T-cell expressed and secreted, and microparticles, which may provide new perspectives for clinical AS evaluation and risk stratification.

Circulating microparticles and the risk of thrombosis in inherited deficiencies of antithrombin, protein C and protein S

Many subjects carrying inherited thrombophilic defects will never experience venous thromboembolism (VTE) while other individuals developed recurrent VTE with no known additional risk factors. High levels of circulating microparticles (MP) have been associated with increased risk of VTE in patients with factor V Leiden and prothrombin G20210A mutation, suggesting a possible contribution of MP in the hypercoagulability of mild genetic thrombophilia. The role of MP as additional risk factor of VTE in carriers of natural clotting inhibitors defects (severe thrombophilia) has never been assessed. Plasma levels of annexin V-MP, endothelial-derived MP (EMP), platelet-derived MP (PMP), tissue factor-bearing MP (TF+) and the MP procoagulant activity (PPL) were measured in 132 carriers of natural anticoagulant deficiencies (25 antithrombin, 63 protein C and 64 protein S defect) and in 132 age and gender-matched healthy controls. Carriers of natural anticoagulant deficiencies, overall and separately considered, presented with higher median levels of annexin V-MP, EMP, PMP, TF+MP and PPL activity than healthy controls (p< 0.001, < 0.001, < 0.01, 0.025 and 0.03, respectively). Symptomatic carriers with a previous episode of VTE had significantly higher median levels of annexin-V MP than those without VTE (p=0.027). Carriers with high levels of annexin V-MP, EMP and PMP had an adjusted OR for VTE of 3.36 (95 % CI, 1.59 to 7.11), 9.26 (95 % CI, 3.55 to 24.1) and 2.72 (95 %CI, 1.16 to 6.38), respectively. Elevated levels of circulating MP can play a role in carriers of mild and severe inherited thrombophilia. The clinical implications of this association remain to be defined.

Circulating microparticles in carriers of prothrombin G20210A mutation

Factor V Leiden (FVL) and prothrombin gene mutation G20210A (PTM) are the two most common genetic polymorphisms known to predispose carriers to venous thromboembolism (VTE). A recent study in FVL carriers showed that circulating levels of microparticles (MP) may contribute to their thrombogenic profile. To further elucidate the prothrombotic state linked to genetic thrombophilia, we extended this study to carriers of PTM. The plasma level of annexin V-MP, endothelial- MP (EMP), platelet-MP (PMP), tissue factor-bearing MP (TF+) and the MP procoagulant activity (PPL) was measured in 124 carriers of PTM (105 heterozygous and 19 homozygous) and in 120 age- and gender-matched healthy individuals. Heterozygous and homozygous carriers of PTM showed significantly increased levels of annexin V-MP (2930 [1440–4646] MP/μl and 3064 [2412–4906] MP/μl, respectively) and significantly shorter PPL clotting time (54 [46–67] sec and 55 [46–64] sec) compared to controls (1728 [782–2122] MP/μl and 71 [61–75] sec, respectively; p<0.01). Similarly, heterozygous and homozygous subjects presented with significantly higher levels of EMP, PMP and TF+ than controls (p<0.05). PTM carriers with a VTE history had significantly higher MP numbers and activity than controls. No significant difference was seen between carriers with and without a VTE history. We conclude that the higher levels of circulating MP found in PTM carriers may play a role in the development of VTE possibly by increasing thrombin generation. Further studies are needed to better define the role of MP as triggering factors for the thrombotic complications characterizing mild genetic thrombophilic defects.

Plasma C4d+ Endothelial Microvesicles Increase in Acute Antibody-Mediated Rejection

BACKGROUND

Antibody-mediated rejection (AMR) is a major cause of kidney allograft loss. Currently, AMR diagnosis relies on biopsy which is an invasive procedure. A noninvasive biomarker of acute AMR could lead to early diagnosis and treatment of this condition and improve allograft outcome. Microvesicles are membrane-bound vesicles released from the cell surface after injury. We hypothesized that because AMR is associated with allograft endothelial injury and C4d deposition, plasma microvesicles positive for endothelial (CD144) marker and C4d are increased in this condition.

METHODS

We studied microvesicle concentration in the plasma of 95 kidney transplant patients with allograft dysfunction and compared with 23 healthy volunteers. Biopsy diagnosis and scoring was performed using Banff classification.

RESULTS

In the 28 subjects with AMR, the density of C4d+/CD144+ microvesicles was on average 11-fold (P = 0.002) higher than transplant recipients with no AMR and 24-fold (P = 0.008) than healthy volunteers. Densities of C4d+ and C4d+/annexin V+ (C4d+/AVB+) microvesicles were also increased in AMR patients compared with no AMR and healthy subjects. C4d+/AVB+ microvesicles correlated with AMR biopsy severity. Nine patients with acute AMR that received treatment showed a mean 72% decrease (P = 0.01) in C4d+/CD144+ microvesicle concentration compared with pretreatment values.

CONCLUSIONS

Quantification of plasma C4d+ microvesicles provides information about presence of AMR, its severity and response to treatment in transplant patients.