Exosomes from red blood cell units bind to monocytes and induce proinflammatory cytokines, boosting T-cell responses in vitro. Blood. 2014;123:687-696. [PMID: 24335232 DOI: 10.1182/blood-2013-10-530469]

Vaccine immune response, autoimmunity and morbidity after neonatal blood exchange transfusion

INTRODUCTION

A blood exchange transfusion (BET) is most commonly performed to treat severe neonatal haemolytic disease. A distinct form of blood transfusion adverse reaction is transfusion-related immunomodulation. The purpose of our retrospective single-centre case-control cohort study was to investigate whether a blood exchange transfusion in the neonatal period provokes immunomodulation and affects humoral immune response to vaccination, morbidity and occurrence of autoantibodies.

METHODS

Study subjects were 74 apparently healthy children, who were born at term as appropriate for gestational age and received four doses of diphtheria and tetanus toxoid vaccine. Forty-one received BET due to neonatal hemolytic disease and no other blood product afterwards, while 33 did not receive any blood products. Analysis of diphtheria, tetanus and autoimmune antibodies was performed and their medical records were analyzed for infectious, allergic, cancerous and autoimmune diseases.

RESULTS

A clearly exaggerated immune response to diphtheria (1.016 IU/mL, 95% confidence interval (CI) 0.662-1.369 IU/mL vs. 0.515 IU/mL, 95% CI 0.363 to 0.626 IU/mL, P = 0.011) and slightly exaggerated immune response to tetanus vaccine (1.798 IU/mL, 95% CI 1.180-2.416 IU/mL vs. 1.036 IU/mL, 95% CI 0.398-1.673 IU/mL, P = non-specific) were observed in BET subjects. A propensity towards autoimmunity (25.8% vs. 12.5%, P = non-specific) was observed in BET subjects. However, BET in the neonatal period did not influence the occurrence of bacterial, childhood viral diseases with exception of varicella (43.9% vs. 21.2%, P = 0.040), autoimmune and cancer diseases.

CONCLUSION

BET impacted humoral immune response to diphtheria and tetanus vaccine and occurrence of autoimmune antibodies, but did not affect morbidity and the occurrence of autoimmune diseases. These effects could be related to massive antigenic load of BET and an accelerated priming of immune cells and consequent immunomodulation.

Decreased erythrocyte CD44 and CD58 expression link e-waste Pb toxicity to changes in erythrocyte immunity in preschool children

Lead (Pb) toxicity damages blood cells and disturbs the immune micro-environment. When Pb enters the circulatory system, >95% of Pb accumulates in erythrocytes. We therefore conducted this study to explore the long-term effect of Pb exposure on expression of erythrocyte adhesion molecules (CD44 and CD58) and related downstream cytokine concentrations. We enrolled a total of 267 preschool children, 2-7 years of age, from Guiyu (e-waste-exposed group, n = 132) and Haojiang (reference group, n = 135) in November and December 2015. We measured child blood Pb, biomarkers including erythrocyte CD44 and CD58, erythrocyte count, leukocyte count and inflammatory cytokines (IL-1β, IL-12p70 and IFN-γ), and calculated erythrocyte Pb levels. Regression model demonstrated that higher erythrocyte Pb was associated with lower CD44 and CD58. Compared to low erythrocyte Pb levels (quartile 1), high erythrocyte Pb levels (quartile 4) were related to lower levels of erythrocyte CD44 and CD58. Elevated blood Pb correlated with higher IL-12p70 and IFN-γ, and lower IL-2. The mediation effect of erythrocyte CD44 on the relationship of erythrocyte Pb with IL-1β and IL-12p70 was significant, and the effect of erythrocyte Pb on IFN-γ was mediated by erythrocyte CD58. The data provides novel translational insight into the relationship between elevated Pb exposure and the change of erythrocyte immunity and downstream cytokine secretion in preschool children.

Extracellular vesicle fibrinogen induces encephalitogenic CD8+ T cells in a mouse model of multiple sclerosis

In this report, we show that fibrinogen, identified by proteomics to be present in blood plasma extracellular vesicles (EVs), is sufficient and required for autoimmune-mediated spontaneous relapsing disease activity in a murine model of multiple sclerosis (MS). Unique to this model is that plasma EVs induced CD8-mediated disease. Analysis of human plasma EVs identified fibrinogen in MS patient samples, thereby providing a compelling translational association between our experimental findings and the perpetuation of CD8-mediated autoimmunity in human MS. Hence, these findings provide evidence for EVs as means by which to model an important aspect of spontaneous CD8+ T cell development related to autoimmunity in MS.

Extracellular vesicles (EVs) are emerging as potent mediators of intercellular communication with roles in inflammation and disease. In this study, we examined the role of EVs from blood plasma (pEVs) in an experimental autoimmune encephalomyelitis mouse model of central nervous system demyelination. We determined that pEVs induced a spontaneous relapsing−remitting disease phenotype in MOG_35–55-immunized C57BL/6 mice. This modified disease phenotype was found to be driven by CD8+ T cells and required fibrinogen in pEVs. Analysis of pEVs from relapsing−remitting multiple sclerosis patients also identified fibrinogen as a significant portion of pEV cargo. Together, these data suggest that fibrinogen in pEVs contributes to the perpetuation of neuroinflammation and relapses in disease.

Extracellular vesicle concentration and procoagulant activity of canine haemoperitoneum fluid and packed red blood cells

OBJECTIVES

To compare the concentration of phosphatidylserine-positive extracellular vesicles and phosphatidylserine-derived procoagulant activity of canine haemoperitoneum fluids and packed red blood cell units.

MATERIALS AND METHODS

Ten dogs with haemoperitoneum (neoplasia = 7; trauma = 1; other = 2) were recruited, and five non-leukoreduced packed red blood cell units purchased. Supernatants were collected from haemoperitoneum samples and packed red blood cell units using a consistent centrifugation protocol. Phosphatidylserine-positive extracellular vesicle concentrations were measured by flow cytometry and phosphatidylserine-mediated procoagulant activity by a commercial thrombin generation assay.

RESULTS

Phosphatidylserine-mediated procoagulant activity was significantly higher for supernatants collected from packed red blood cell units (median 54 nM, range 53 to 60 nM) than haemoperitoneum samples (median 43 nM; range 7 to 51 nM; P = 0.0007). By flow cytometry, the concentration of phosphatidylserine-positive extracellular vesicles was not significantly different between packed red blood cell (median: 415/μL, range 173 to 1331/μL) and haemoperitoneum samples (median: 314/μL, range 132 to 3880/μL; P = 0.77).

CLINICAL SIGNIFICANCE

This study does not suggest that shed abdominal blood contains more extracellular vesicles with phosphatidylserine-mediated procoagulant activity than donor packed red blood cell units. Clinical studies to compare the effects of autologous transfusion of shed abdominal blood and packed red blood cell units on coagulation status and clinical outcome are required.

Immunomodulatory effects of plasma products on monocyte function in vitro

BACKGROUND

Restoration of a balanced innate immune response is paramount to recovery from critical injury. Plasma transfusion may modulate innate immune responses; however, little is known about the immunomodulatory potential of various plasma products. We conducted in vitro experiments to determine the effects of fresh frozen plasma, thawed plasma, solvent/detergent plasma, and an investigational spray-dried solvent/detergent plasma product on monocyte function.

METHODS

Monocytes were isolated from healthy adult volunteers and cocultured with aliquots of autologous plasma (control), fresh frozen plasma, thawed plasma, solvent/detergent treated plasma, or spray-dried solvent/detergent plasma. Monocyte function was assessed by cytokine production with and without lipopolysaccharide (LPS) stimulation, and flow cytometric assessment of HLA-DR cell surface expression.

RESULTS

Monocyte cytokine production was not significantly altered after exposure to fresh frozen plasma or thawed plasma. In the absence of LPS, spray-dried solvent/detergent plasma exposure resulted in markedly increased IL-8 production compared to other plasma groups and controls (p = 0.01, analysis of variance [ANOVA]). Likewise, spray-dried SD plasma exposure resulted in higher LPS-induced IL-8, TNFα, and IL-1β production compared with autologous plasma controls (p < 0.0001; p < 0.0001, p = 0.002, respectively; ANOVA). LPS-induced IL-8 and TNFα production was lowest after exposure to solvent/detergent plasma (p < 0.0001, ANOVA).

CONCLUSION

Exposure to spray-dried solvent/detergent plasma resulted in marked augmentation of monocyte inflammatory cytokine production. Solvent/detergent plasma exposure resulted in the lowest cytokine production, suggesting lower immunomodulatory potential. Further work is needed to determine how these in vitro findings may translate to the bedside.

Influence of blood storage age on immune and coagulation parameters in critically ill transfused patients

BACKGROUND

Several retrospective studies have suggested that transfusion with red blood cells (RBCs) stored for longer periods is associated with increased mortality. The Age of Blood Evaluation (ABLE) study randomized subjects to receive fresh vs. standard issue RBC units and showed no difference in the primary or secondary endpoints of mortality or change in multi-organ dysfunction syndrome (MODS) score.

METHODS

In this study a subset of 100 ABLE subjects were enrolled to measure coagulation and immune parameters. Samples were collected pre-transfusion and on days 2, 6, 28, and 180 post-transfusion. Levels of 16 coagulation parameters, regulatory and functional T cells, 25 cytokines, and 16 markers of extracellular vesicles (EVs) were determined.

RESULTS

Changes from baseline in levels of protein C, factor V, and EVs expressing phosphatidyl serine and CTLA-4 (CD152) differed between recipients of fresh and standard storage age RBC units, with the vast majority of coagulation and EV markers and all cytokines tested showing no difference between study arms. Although most analytes showed no difference between subjects in the fresh and standard arms of the study, 6 coagulation parameters, 15 cytokines, and 7 EV parameters changed significantly in the period post-transfusion.

DISCUSSION

Transfusion of fresh vs. standard issue RBC units does not result in substantial changes in coagulation or immune parameters, up to day 35 of RBC storage. Furthermore, significant changes in multiple coagulation and immune parameters are detectable post-transfusion, though causality cannot be determined based on the current study.

Peripheral Blood Cell Interactions of Cancer-Derived Exosomes Affect Immune Function

Cancer-derived exosomes are constitutively produced and secreted into the blood and biofluids of their host patients providing a liquid biopsy for early detection and diagnosis. Given their ubiquitous nature, cancer exosomes influence biological mechanisms that are beneficial to the tumor cells where they are produced and the microenvironment in which these tumors exist. Accumulating evidence suggests that exosomes transport proteins, lipids, DNA, mRNA, miRNA and long non coding RNA (lncRNA) for the purpose of cell-cell and cell-extracellular communication. These exosomes consistently reflect the status as well as identity of their cell of origin and as such may conceivably be affecting the ability of a functional immune system to recognize and eliminate cancer cells. Recognizing and mapping the pathways in which immune suppression is garnered through these tumor derived exosome (TEX) may lead to treatment strategies in which specific cell membrane proteins or receptors may be targeted, allowing for immune surveillance to once again help with the treatment of cancer. This Review focuses on how cancer exosomes interact with immune cells in the blood.

Extracellular Vesicles in Red Blood Cell Concentrates: An Overview

Red blood cell (RBC) concentrates may be stored for up to 42 days before transfusion to a patient. During storage extracellular vesicles (EVs) develop and can be detected in significant amounts in RBC concentrates. The concentration of EVs is affected by component preparation methods, storage solutions, and inter-donor variation. Laboratory investigations have focused on the effect of EVs on in vitro assays of thrombin generation and immune responses. Assays for EVs in RBC concentrates are not standardized. The aims of this review are to describe the factors that determine the presence of erythrocyte-EVs in RBC concentrates, the current techniques used to characterize them, and the potential role of EV analysis as a quality control maker for RBC storage.

Tumor-derived exosomal HMGB1 promotes esophageal squamous cell carcinoma progression through inducing PD1+ TAM expansion

Macrophages constitute one of the most common components of immune cells, which penetrate tumors and they have a key role in tumor prognosis. Here, we identified an unrecognized macrophage subpopulation, which favors tumorigenesis. These macrophages express programmed cell death protein 1 (PD1) in a constitutive manner and accumulates in esophageal squamous cell carcinoma (ESCC) in advanced stage of the disease and is negatively associated with the survival of ESCC patients. The PD1⁺ tumor-associated macrophages (PD1⁺ TAMs) displayed surface pattern and function akin to M2: a substantial enhancement in CD206 and IL-10 expression; a specific reduction in HLA-DR, CD64, and IL-12 expression; and a significant increase in the ability to inhibit CD8⁺ T-cell proliferation. Triggering of PD1 signal is effective in increasing PD1⁺ TAM function. Moreover, exosomal HMGB1 obtained from tumors are efficient in triggering differentiation of monocytes into PD1⁺ TAMs, which display phenotypic and functional properties of M2. Overall, our work is the first finding to confirm that exosomal HMGB1 obtained from ESCC can successfully trigger clonal expansion of PD1⁺ TAM. Further, as the macrophages exhibit an M2-like surface profile and function, thereby creating conditions for development of ESCC. Thus, effective methods of treatment include combining immunotherapy with targeting PD1⁺ TAMs and tumor-derived exosomal HMGB1 to resuscitate immune function in individuals suffering from ESCC.

Exosomes from β-cells alleviated hyperglycemia and enhanced angiogenesis in islets of streptozotocin-induced diabetic mice

PURPOSE

Exosomes are small nanoscale vesicles secreted from cells. Exosome-based therapeutic approaches have been evaluated in treating ischemic diseases. In the present study, we explored the effect of exosomes on streptozotozin (STZ)-induced diabetic mouse and its underlying mechanisms.

METHODS

Exosomes were isolated from MIN6 cells. Transmission electron microscopy, dynamic light scattering and Western blot were used to identify the exosomes. STZ was used to establish diabetic or abnormal glucose tolerance mouse model. Histology study and flow cytometry were applied to detect the changes in immune responses.

RESULTS

Transplantation of the exosomes into diabetic mice resulted in a longer median survival time compared with the untreated diabetic mice (P<0.01). Transplantation of the exosomes improved glucose tolerance, increased insulin content and preserved the architectures of islets in mice with abnormal glucose tolerance. Moreover, exosome treatment enhanced the expression of CD31, a marker of endothelial cells, and tended to reduce macrophage infiltration in islets of STZ-treated mice.

CONCLUSION

Exosomes derived from β-cells play a role in preserving pancreatic islet architecture and its function, and in inducing islet angiogenesis, which implicates that exosome treatment could be a novel therapeutic strategy for diabetes.

Red blood cell storage lesion: causes and potential clinical consequences

Red blood cells (RBCs) are a specialised organ that enabled the evolution of multicellular organisms by supplying a sufficient quantity of oxygen to cells that cannot obtain oxygen directly from ambient air via diffusion, thereby fueling oxidative phosphorylation for highly efficient energy production. RBCs have evolved to optimally serve this purpose by packing high concentrations of haemoglobin in their cytosol and shedding nuclei and other organelles. During their circulatory lifetimes in humans of approximately 120 days, RBCs are poised to transport oxygen by metabolic/redox enzymes until they accumulate damage and are promptly removed by the reticuloendothelial system. These elaborate evolutionary adaptions, however, are no longer effective when RBCs are removed from the circulation and stored hypothermically in blood banks, where they develop storage-induced damages ("storage lesions") that accumulate over the shelf life of stored RBCs. This review attempts to provide a comprehensive view of the literature on the subject of RBC storage lesions and their purported clinical consequences by incorporating the recent exponential growth in available data obtained from "omics" technologies in addition to that published in more traditional literature. To summarise this vast amount of information, the subject is organised in figures with four panels: i) root causes; ii) RBC storage lesions; iii) physiological effects; and iv) reported outcomes. The driving forces for the development of the storage lesions can be roughly classified into two root causes: i) metabolite accumulation/depletion, the target of various interventions (additive solutions) developed since the inception of blood banking; and ii) oxidative damages, which have been reported for decades but not addressed systemically until recently. Downstream physiological consequences of these storage lesions, derived mainly by in vitro studies, are described, and further potential links to clinical consequences are discussed. Interventions to postpone the onset and mitigate the extent of the storage lesion development are briefly reviewed. In addition, we briefly discuss the results from recent randomised controlled trials on the age of stored blood and clinical outcomes of transfusion.

Tumor-derived microRNAs induce myeloid suppressor cells and predict immunotherapy resistance in melanoma

The accrual of myeloid-derived suppressor cells (MDSCs) represents a major obstacle to effective immunotherapy in cancer patients, but the mechanisms underlying this process in the human setting remain elusive. Here, we describe a set of microRNAs (miR-146a, miR-155, miR-125b, miR-100, let-7e, miR-125a, miR-146b, miR-99b) that are associated with MDSCs and resistance to treatment with immune checkpoint inhibitors in melanoma patients. The miRs were identified by transcriptional analyses as being responsible for the conversion of monocytes into MDSCs (CD14+HLA-DRneg cells) mediated by melanoma extracellular vesicles (EVs) and were shown to recreate MDSC features upon transfection. In melanoma patients, these miRs were increased in circulating CD14+ monocytes, plasma, and tumor samples, where they correlated with the myeloid cell infiltrate. In plasma, their baseline levels clustered with the clinical efficacy of CTLA-4 or programmed cell death protein 1 (PD-1) blockade. Hence, MDSC-related miRs represent an indicator of MDSC activity in cancer patients and a potential blood marker of a poor immunotherapy outcome.

Immune Response to Extracellular Vesicles From Human Islets of Langerhans in Patients With Type 1 Diabetes

The autoimmune response that characterizes type 1 diabetes (T1D) has no clear cause. Extracellular vesicles (EVs) play an important role in triggering the immune response in other contexts. Here, we propose a model by which EVs isolated from human islets stimulate proinflammatory immune responses and lead to peripheral blood mononuclear cell (PBMC) activation. We show that human islet EVs are internalized by monocytes and B cells and lead to an increase in T-helper 1, 2, and 17 cytokine expression, as well as T and B cell proliferation. Importantly, we demonstrate memory T and B cell activation by EVs selectively in PBMCs of patients with T1D. Additionally, human islet EVs induce an increase in antibodies against glutamic acid decarboxylase 65 (GAD65) in T1D PBMCs. Furthermore, pretreatment of T1D PBMCs with ibrutinib, an inhibitor of Bruton tyrosine kinase, dampens EV-induced memory B cell activation and GAD65 antibody production. Collectively, our findings indicate a role for human islet EVs in mediating activation of B and T cells and GAD65 autoantibody production.

Enhancement of antitumor potency of extracellular vesicles derived from natural killer cells by IL-15 priming

PURPOSE

Natural killer (NK) cells are the key subset of innate-immunity lymphocytes; they possess antitumor activities and are used for cancer immunotherapy. In a previous study, extracellular vehicles (EVs) from NK-92MI cells were isolated and exploited for their ability to kill human cancer cells in vitro and in vivo (multiple injection methods). Here, the potential of NK-cell-derived EVs (NK-EVs) for immunotherapy was improved by priming with interleukin (IL)-15.

METHODS

NK-EVs were isolated from the culture medium without or with IL-15 (NK-EVs_IL-15) by ultracentrifugation and were purified via density gradient ultracentrifugation. In addition, NK-EVs and NK-EVs_IL-15 were characterized by transmission electron microscopy, nanoparticle-tracking analysis, and western blotting. Flow cytometry, bioluminescence imaging, and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay were performed for apoptosis, protein expression, cell proliferation, and cytotoxicity analyses. Furthermore, xenograft tumor-bearing mice were injected with PBS, NK-EVs, or NK-EVs_IL-15 intravenously five times. Tumor growth was monitored using calipers and bioluminescence imaging. Toxicity of the nanoparticles was evaluated by measuring the body weight of the mice.

RESULTS

NK-EVs_IL-15 showed significantly higher cytolytic activity toward human cancer cell lines (glioblastoma, breast cancer, and thyroid cancer) and simultaneously increased the expression of molecules associated with NK-cell cytotoxicity. When compared with NK-EVs, NK-EVs_IL-15 significantly inhibited the growth of glioblastoma xenograft cells in mice. In addition, both NK-EVs and NK-EVs_IL-15 were not significantly toxic to either normal cells or mice.

CONCLUSION

IL-15 may improve the immunotherapeutic effects of NK-EVs, thus improving the applications of NK-EVs in the future.

Screening of red blood cells for extracellular vesicle content as a product quality indicator

BACKGROUND

The controversy around the quality and clinical impact of stored and differentially manufactured red cell concentrates (RCCs) from different donor groups is ongoing. Current studies are limited by the lack of quality measures suitable for routine screening of RCCs. As extracellular vesicles (EVs) are markers of cellular activation or degradation, this study investigated the utility of EV screening to characterize the effects of RBCs production methods and storage.

STUDY DESIGN AND METHODS

RCCs were prepared by whole blood filtration or red blood cell (RBC) filtration methods, centrifuged to prepare a supernatant, and tested for EV content (dynamic light scattering or tunable resistive pulse-sensing techniques), hemolysis, ATP, and RBC deformability on Days 7, 21, and 42 of storage. To simulate nondestructive quality control (QC) testing, 1 RBC unit was tested in parallel with six 10-mL aliquots that were stored in small-volume containers.

RESULTS

EV content showed a linear increase with storage time (p < 0.001) and correlated with supernatant hemoglobin and inversely with ATP or RBC deformability. The method of component manufacturing influenced the characteristics of the EVs during storage. A strong correlation between both EV testing methods' measure of total EV was observed. EV content in the six aliquots were consistent at each time point but statistically higher than in the original RCCs on and after 21 days of storage.

CONCLUSIONS

EV content correlates with measures of hemolysis and other RBC quality indicators and could be implemented as a routine screening tool for nondestructive QC testing of RCCs.

Analysis of Epididymal Protein Synthesis and Secretion

The mammalian epididymis generates one of the most complex intraluminal fluids of any endocrine gland in order to support the post-testicular maturation and storage of spermatozoa. Such complexity arises due to the combined secretory and absorptive activity of the lining epithelial cells. Here, we describe the techniques for the analysis of epididymal protein synthesis and secretion by focusing on the model protein family of dynamin (DNM) mechanoenzymes; large GTPases that have the potential to regulate bi-directional membrane trafficking events. For the study of protein expression in epididymal tissue, we describe robust methodology for immunofluorescence labeling of target proteins in paraffin-embedded sections and the subsequent detection of the spatial distribution of these proteins via immunofluorescence microscopy. We also describe optimized methodology for the isolation and characterization of exosome like vesicles, known as epididymosomes, which are secreted into the epididymal lumen to participate in intercellular communication with maturing sperm cells. As a complementary approach, we also describe the immunofluorescence detection of target proteins in an SV40-immortalized mouse caput epididymal epithelial (mECap18) cell line. Moreover, we discuss the utility of the mECap18 cell line as a suitable in vitro model with which to explore the regulation of epididymal secretory activity. For this purpose, we describe the culturing requirements for the maintenance of the mECap18 cell line and the use of selective pharmacological inhibition regimens that are capable of influencing their secretory protein profile. The latter are readily assessed via harvesting of conditioned culture medium, concentration of secreted proteins via trichloroacetic acid/acetone precipitation and their subsequent analysis via SDS-PAGE and immunoblotting. We contend that these combined methods are suitable for the analysis of alternative epididymal protein targets as a prelude to determining their functional role in sperm maturation and/or storage.

In vivo Non-invasive Imaging of Radio-Labeled Exosome-Mimetics Derived From Red Blood Cells in Mice

Exosomes are natural nano-sized membrane vesicles that have garnered recent interest owing to their potential as drug delivery vehicles. Though exosomes are effective drug carriers, their production and in vivo biodistribution are still not completely elucidated. We analyzed the production of exosome mimetics (EMs) from red blood cells (RBCs) and the radio-labeling of the RBC-EMs for in vivo imaging. Engineered EMs from RBCs were produced in large-scale by a one-step extrusion method, and further purified by density-gradient centrifugation. RBC-EMs were labeled with technetium-99m (^99mTc). For non-invasive imaging, ^99mTc (free) or ^99mTc-RBC-EMs were injected in mice, and their biodistribution was analyzed by gamma camera imaging. Animals were sacrificed, and organs were collected for further biodistribution analysis. RBC-EMs have similar characteristics as the RBC exosomes but have a 130-fold higher production yield in terms of particle numbers. Radiochemical purity of ^99mTc-RBC-EMs was almost 100% till 2 h reduced to 97% at 3 h. Radio-labeling did not affect the size and morphology of RBC-EMs. In contrast to free ^99mTc, in vivo imaging of ^99mTc-RBC-EMs in mice showed higher uptake in the liver and spleen, and no uptake in the thyroid. Ex vivo imaging confirmed the in vivo findings. Furthermore, fluorescent imaging confirmed the nuclear imaging findings. Immunofluorescent imaging revealed that the hepatic uptake of RBC-EMs was significantly mediated by kupffer cells (resident hepatic macrophages). Our results demonstrate a simple yet large-scale production method for a novel type of RBC-EMs, which can be effectively labeled with ^99mTc, and feasibly monitored in vivo by nuclear imaging. The RBC-EMs may be used as in vivo drug delivery vehicles.

Glucocorticoids inhibit production of exosomes containing inflammatory microRNA-155 in lipopolysaccharide-induced macrophage inflammatory responses

Glucocorticoids are anti-inflammatory agents that are widely used in clinical practice. Increasing evidence has identified exosomes as important mediators in inflammation, but it is unknown whether glucocorticoids regulate exosome secretion and function. In the present study, we observed a reduction of exosome secretion in lipopolysaccharide (LPS)-induced RAW264.7 macrophages following treatment with dexamethasone. Importantly, exosomes isolated from LPS-induced RAW264.7 macrophages increased TNF-α and IL-6 production in RAW264.7 cells. However, this increase was less pronounced following treatment with exosomes isolated from dexamethasone-treated cells. Moreover, dexamethasone decreased expression of pro-inflammatory microRNA-155 in exosomes from LPS-induced RAW264.7 macrophages. We postulate that exosomes are novel targets in the anti-inflammatory effect of glucocorticoids in LPS-induced macrophage inflammatory responses. These findings will benefit the development of new approaches for anti-inflammatory therapeutics.

Semen inhibits Zika virus infection of cells and tissues from the anogenital region

Zika virus (ZIKV) causes severe birth defects and can be transmitted via sexual intercourse. Semen from ZIKV-infected individuals contains high viral loads and may therefore serve as an important vector for virus transmission. Here we analyze the effect of semen on ZIKV infection of cells and tissues derived from the anogenital region. ZIKV replicates in all analyzed cell lines, primary cells, and endometrial or vaginal tissues. However, in the presence of semen, infection by ZIKV and other flaviviruses is potently inhibited. We show that semen prevents ZIKV attachment to target cells, and that an extracellular vesicle preparation from semen is responsible for this anti-ZIKV activity. Our findings suggest that ZIKV transmission is limited by semen. As such, semen appears to serve as a protector against sexual ZIKV transmission, despite the availability of highly susceptible cells in the anogenital tract and high viral loads in this bodily fluid.

Granulocyte-Derived Extracellular Vesicles Activate Monocytes and Are Associated With Mortality in Intensive Care Unit Patients

To understand how extracellular vesicle (EV) subtypes differentially activate monocytes, a series of in vitro studies were performed. We found that plasma-EVs biased monocytes toward an M1 profile. Culturing monocytes with granulocyte-, monocyte-, and endothelial-EVs induced several pro-inflammatory cytokines. By contrast, platelet-EVs induced TGF-β and GM-CSF, and red blood cell (RBC)-EVs did not activate monocytes in vitro. The scavenger receptor CD36 was important for binding of RBC-EVs to monocytes, while blockade of CD36, CD163, CD206, TLR1, TLR2, and TLR4 did not affect binding of plasma-EVs to monocytes in vitro. To identify mortality risk factors, multiple soluble factors and EV subtypes were measured in patients' plasma at intensive care unit admission. Of 43 coagulation factors and cytokines measured, two were significantly associated with mortality, tissue plasminogen activator and cystatin C. Of 14 cellular markers quantified on EVs, 4 were early predictors of mortality, including the granulocyte marker CD66b. In conclusion, granulocyte-EVs have potent pro-inflammatory effects on monocytes in vitro. Furthermore, correlation of early granulocyte-EV levels with mortality in critically ill patients provides a potential target for intervention in management of the pro-inflammatory cascade associated with critical illness.

Emergence of exosomal DNA in molecular neuropathology

Background:

Exosomes are small vesicles of sizes between 40 and 100 nm. They are actively segregated by numerous different cell types and they can be found in almost all body fluids. Thus, there is an emerging role of exosomes and exosomal deoxyribonucleic acid (exoDNA) in biomedical research, especially in molecular medicine. Exosomes are assembled and segregated actively and carry distinct surface markers for cellular communication. They are loaded with cargo such as DNA, ribonucleic acid (RNA) and proteins. As there are numerous different exosomal purification methods available, it is of essential need to select an appropriate technique to get reliable results. As neuropathology is faced with the challenge that brain tissue is not accessible in an easy fashion, exosomes represent an ideal tool for molecular neuropathology. Thus, disease-specific molecular alterations will be detectable in a minimally invasive way for early disease diagnosis and surveillance.

Summary:

The analysis of exoDNA as biomarkers in neuropathology will enable early diagnosis, monitoring and relapse detection of brain tumors and neuropsychiatric disorders.

Outlook:

It is assumed that the significance of exosomes will increase in the upcoming years. There are powerful approaches in development using exosomes in molecularly targeted therapy to ultimately cure devastating brain diseases.

Targeting and Therapy of Glioblastoma in a Mouse Model Using Exosomes Derived From Natural Killer Cells

Objective

Glioblastoma is a highly aggressive primary brain tumor that is resistant to radiotherapy and chemotherapy. Natural killer (NK) cells have been used to treat incurable cancers. Recent studies have investigated the effectiveness of NK-cell-derived exosomes (NK-Exo) for treating incurable cancers such as melanoma, leukemia, and neuroblastoma; however, NK-Exo have not been used to treat glioblastoma. In the present study, we investigated the antitumor effects of NK-Exo against aggressive glioblastoma both in vitro and in vivo and determined the tumor-targeting ability of NK-Exo by performing fluorescence imaging.

Methods

U87/MG cells were transfected with the enhanced firefly luciferase (effluc) and thy1.1 genes; thy1.1-positive cells were selected using microbeads. U87/MG/F cells were assessed by reverse transcription polymerase chain reaction (RT-PCR), western blotting, and luciferase-activity assays. NK-Exo were isolated by ultracentrifugation, purified by density gradient centrifugation, and characterized by transmission electron microscopy, dynamic light scattering (DLS), nanoparticle-tracking analysis (NTA), and western blotting. Cytokine levels in NK-Exo were compared to those in NK cells and NK-cell medium by performing an enzyme-linked immunosorbent assay (ELISA). NK-Exo-induced apoptosis of cancer cells was confirmed by flow cytometry and western blotting. In vivo therapeutic effects and specificity of NK-Exo against glioblastoma were assessed in a xenograft mouse model by fluorescence imaging. Xenograft mice were treated with NK-Exo, which was administered seven times through the tail vein. Tumor growth was monitored by bioluminescence imaging (BLI), and tumor volume was measured by ultrasound imaging. The mice were intraperitoneally injected with dextran sulfate 2 h before NK-Exo injection to decrease the liver uptake and increase the tumor specificity of NK-Exo.

Results

RT-PCR and western blotting confirmed the gene and protein expression of effluc in U87/MG/F cells, with the bioluminescence activity of U87/MG/F cells increasing with an increase in cell number. NTA and DLS results indicated that the size of NK-Exo was ~100 nm, and the western blot results confirmed that NK-Exo expressed exosome markers CD63 and Alix. We confirmed the in vitro cytotoxic effects of NK-Exo on U87/MG/F cells by performing BLI, and the killing effect on U87/MG and U87MG/F cells was measured by CCK-8 and MTT assays (p < 0.001). ELISA results indicated that NK-Exo contained tumor necrosis factor-α and granzyme B. In vivo NK-Exo treatment inhibited tumor growth compared to in control mice (p < 0.001), and pretreatment of xenograft mice with dextran sulfate 2 h before NK-Exo treatment increased the antitumor effect of NK-Exo (p < 0.01) compared to in control and NK-Exo-alone-treated mice.

Conclusion

NK-Exo targeted and exerted antitumor effects on glioblastoma cells both in vitro and in vivo, suggesting their utility in treating incurable glioblastoma.

Prognostic Significance of Blood Transfusion in Elderly Patients with Primary Diffuse Large B-Cell Lymphoma

The current study sought to evaluate whether blood transfusions affect survival of elderly patients with primary diffuse large B-cell lymphoma (DLBCL). A total of 104 patients aged 60 years and over were enrolled and divided into two groups: 24 patients who received transfusions and 80 patients who did not. Statistical analyses showed significant differences in LDH levels, platelet (Plt) counts, and hemoglobin (Hb) and albumin (Alb) levels between the two groups. Univariate analyses showed that LDH level ≥ 245 IU/L, cell of origin (germinal center/nongerminal center), and blood transfusion were associated with both overall survival (OS) and progression-free survival (PFS). Higher IPI (3–5), Alb level < 35 g/L, and rituximab usage were associated with OS. Appearance of B symptoms was associated with PFS. Multivariate analyses showed that cell of origin and rituximab usage were independent factors for OS and LDH level was an independent factor for PFS. Blood transfusion was an independent factor for PFS, but not for OS. Our preliminary results suggested that elderly patients with primary DLBCL may benefit from a restrictive blood transfusion strategy.

Characteristics of Extracellular Vesicles in Red Blood Concentrates Change with Storage Time and Blood Manufacturing Method

Background

Extracellular vesicles (EVs) in blood products are potential effectors of inflammation and coagulation after transfusion. The aim of this study was to assess the impact of different blood manufacturing methods and duration of hypothermic storage on the EV subpopulations in relation to other in vitro quality parameters of red blood cell concentrate (RCC) products.

Methods

RCCs were produced using whole blood filtration (WBF) or red cell filtration (RCF) (n = 12/method), refrigerated for 43 days, and evaluated for EV size profile and concentration, red cell deformability, ATP and 2,3-DPG, hemolysis, and hematological indices.

Results

The total number of EVs increased significantly with storage in both methods, and WBF-RCCs contained the higher numbers of EVs compared to RCF-RCCs. The concentration of small EVs was greater in WBF-RCCs versus RCF-RCCs, with difference between the two methods observed on day 43 of storage (p = 0.001). Throughout storage, significant decreases were identified in ATP, 2,3-DPG, and EI_max, while an increase in hemolysis was observed in both RCC products.

Conclusion

The dynamic shift in the size and concentration of the EV subpopulations is dependent on the blood manufacturing method and length of storage. Better understanding of the potential clinical implications of these heterogeneous populations of EVs are needed.

Role of heme in lung bacterial infection after trauma hemorrhage and stored red blood cell transfusion: A preclinical experimental study

BACKGROUND

Trauma is the leading cause of death and disability in patients aged 1-46 y. Severely injured patients experience considerable blood loss and hemorrhagic shock requiring treatment with massive transfusion of red blood cells (RBCs). Preclinical and retrospective human studies in trauma patients have suggested that poorer therapeutic efficacy, increased severity of organ injury, and increased bacterial infection are associated with transfusion of large volumes of stored RBCs, although the mechanisms are not fully understood.

METHODS AND FINDINGS

We developed a murine model of trauma hemorrhage (TH) followed by resuscitation with plasma and leukoreduced RBCs (in a 1:1 ratio) that were banked for 0 (fresh) or 14 (stored) days. Two days later, lungs were infected with Pseudomonas aeruginosa K-strain (PAK). Resuscitation with stored RBCs significantly increased the severity of lung injury caused by P. aeruginosa, as demonstrated by higher mortality (median survival 35 h for fresh RBC group and 8 h for stored RBC group; p < 0.001), increased pulmonary edema (mean [95% CI] 106.4 μl [88.5-124.3] for fresh RBCs and 192.5 μl [140.9-244.0] for stored RBCs; p = 0.003), and higher bacterial numbers in the lung (mean [95% CI] 1.2 × 10(7) [-1.0 × 10(7) to 2.5 × 10(7)] for fresh RBCs and 3.6 × 10(7) [2.5 × 10(7) to 4.7 × 10(7)] for stored RBCs; p = 0.014). The mechanism underlying this increased infection susceptibility and severity was free-heme-dependent, as recombinant hemopexin or pharmacological inhibition or genetic deletion of toll-like receptor 4 (TLR4) during TH and resuscitation completely prevented P. aeruginosa-induced mortality after stored RBC transfusion (p < 0.001 for all groups relative to stored RBC group). Evidence from studies transfusing fresh and stored RBCs mixed with stored and fresh RBC supernatants, respectively, indicated that heme arising both during storage and from RBC hemolysis post-resuscitation plays a role in increased mortality after PAK (p < 0.001). Heme also increased endothelial permeability and inhibited macrophage-dependent phagocytosis in cultured cells. Stored RBCs also increased circulating high mobility group box 1 (HMGB1; mean [95% CI] 15.4 ng/ml [6.7-24.0] for fresh RBCs and 50.3 ng/ml [12.3-88.2] for stored RBCs), and anti-HMGB1 blocking antibody protected against PAK-induced mortality in vivo (p = 0.001) and restored macrophage-dependent phagocytosis of P. aeruginosa in vitro. Finally, we showed that TH patients, admitted to the University of Alabama at Birmingham ER between 1 January 2015 and 30 April 2016 (n = 50), received high micromolar-millimolar levels of heme proportional to the number of units transfused, sufficient to overwhelm endogenous hemopexin levels early after TH and resuscitation. Limitations of the study include lack of assessment of temporal changes in different products of hemolysis after resuscitation and the small sample size precluding testing of associations between heme levels and adverse outcomes in resuscitated TH patients.

CONCLUSIONS

We provide evidence that large volume resuscitation with stored blood, compared to fresh blood, in mice increases mortality from subsequent pneumonia, which occurs via mechanisms sensitive to hemopexin and TLR4 and HMGB1 inhibition.

Mechanisms of red blood cell transfusion-related immunomodulation

Red blood cell (RBC) transfusion is common in critically ill, postsurgical, and posttrauma patients in whom both systemic inflammation and immune suppression are associated with adverse outcomes. RBC products contain a multitude of immunomodulatory mediators that interact with and alter immune cell function. These interactions can lead to both proinflammatory and immunosuppressive effects. Defining clinical outcomes related to immunomodulatory effects of RBCs in transfused patients remains a challenge, likely due to complex interactions between individual blood product characteristics and patient-specific risk factors. Unpacking these complexities requires an in-depth understanding of the mechanisms of immunomodulatory effects of RBC products. In this review, we outline and classify potential mediators of RBC transfusion-related immunomodulation and provide suggestions for future research directions.

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.

Proceedings of the Food and Drug Administration's public workshop on new red blood cell product regulatory science 2016

The US Food and Drug Administration (FDA) held a workshop on red blood cell (RBC) product regulatory science on October 6 and 7, 2016, at the Natcher Conference Center on the National Institutes of Health (NIH) Campus in Bethesda, Maryland. The workshop was supported by the National Heart, Lung, and Blood Institute, NIH; the Department of Defense; the Office of the Assistant Secretary for Health, Department of Health and Human Services; and the Center for Biologics Evaluation and Research, FDA. The workshop reviewed the status and scientific basis of the current regulatory framework and the available scientific tools to expand it to evaluate innovative and future RBC transfusion products. A full record of the proceedings is available on the FDA website (http://www.fda.gov/BiologicsBloodVaccines/NewsEvents/WorkshopsMeetingsConferences/ucm507890.htm). The contents of the summary are the authors' opinions and do not represent agency policy.

Phospholipid composition of packed red blood cells and that of extracellular vesicles show a high resemblance and stability during storage

Red blood cells (RBCs) are stored up to 35-42days at 2-6°C in blood banks. During storage, the RBC membrane is challenged by energy depletion, decreasing pH, altered cation homeostasis, and oxidative stress, leading to several biochemical and morphological changes in RBCs and to shedding of extracellular vesicles (EVs) into the storage medium. These changes are collectively known as RBC storage lesions. EVs accumulate in stored RBC concentrates and are, thus, transfused into patients. The potency of EVs as bioactive effectors is largely acknowledged, and EVs in RBC concentrates are suspected to mediate some adverse effects of transfusion. Several studies have shown accumulation of lipid raft-associated proteins in RBC EVs during storage, whereas a comprehensive phospholipidomic study on RBCs and corresponding EVs during the clinical storage period is lacking. Our mass spectrometric and chromatographic study shows that RBCs maintain their major phospholipid (PL) content well during storage despite abundant vesiculation. The phospholipidomes were largely similar between RBCs and EVs. No accumulation of raft lipids in EVs was seen, suggesting that the primary mechanism of RBC vesiculation during storage might not be raft -based. Nonetheless, a slight tendency of EV PLs for shorter acyl chains was observed.

Point-of-care washing of allogeneic red blood cells for the prevention of transfusion-related respiratory complications (WAR-PRC): a protocol for a multicenter randomised clinical trial in patients undergoing cardiac surgery

INTRODUCTION

The transfusion-related respiratory complications, transfusion-related acute lung injury (TRALI) and transfusion-associated circulatory overload (TACO), are leading causes of transfusion-related morbidity and mortality. At present, there are no effective preventive strategies with red blood cell (RBC) transfusion. Although mechanisms remain incompletely defined, soluble biological response modifiers (BRMs) within the RBC storage solution may play an important role. Point-of-care (POC) washing of allogeneic RBCs may remove these BRMs, thereby mitigating their impact on post-transfusion respiratory complications.

METHODS AND ANALYSIS

This is a multicenter randomised clinical trial of standard allogeneic versus washed allogeneic RBC transfusion for adult patients undergoing cardiac surgery testing the hypothesis that POC RBC washing is feasible, safe, and efficacious and will reduce recipient immune and physiologic responses associated with transfusion-related respiratory complications. Relevant clinical outcomes will also be assessed. This investigation will enrol 170 patients at two hospitals in the USA. Simon's two-stage design will be used to assess the feasibility of POC RBC washing. The primary safety outcomes will be assessed using Wilcoxon Rank-Sum tests for continuous variables and Pearson chi-square test for categorical variables. Standard mixed modelling practices will be employed to test for changes in biomarkers of lung injury following transfusion. Linear regression will assess relationships between randomised group and post-transfusion physiologic measures.

ETHICS AND DISSEMINATION

Safety oversight will be conducted under the direction of an independent Data and Safety Monitoring Board (DSMB). Approval of the protocol was obtained by the DSMB as well as the institutional review boards at each institution prior to enrolling the first study participant. This study aims to provide important information regarding the feasibility of POC washing of allogeneic RBCs and its potential impact on ameliorating post-transfusion respiratory complications. Additionally, it will inform the feasibility and scientific merit of pursuing a more definitive phase II/III clinical trial.

REGISTRATION

ClinicalTrials.gov registration number is NCT02094118 (Pre-results).

Exploring donor and product factors and their impact on red cell post-transfusion outcomes

The impact of donor characteristics, red cell age, and red cell processing methods on recipient outcomes is an emerging area of research. Knowledge generated from exploring this transfusion continuum has the potential to change the way donors are selected and how donations are processed and stored with important clinical and operational impact. Recently, donor characteristics including age, gender, donation frequency, genetics, and ethnicity have been shown to affect product quality and possibly recipient outcomes. The structural, biochemical and immunological changes that occur with red cell storage appear to not cause harm to blood recipients after 14 randomized clinical trials. However, both in vitro and clinical data are now beginning to question the safety of blood stored for a shorter duration. Whole blood filtration, a method of blood processing, has been linked to inferior recipient outcomes when compared to red cell filtration. Collectively, this emerging body of literature suggests that pre-transfusion parameters impact product quality and recipient outcomes and that no 2 units of red cells are quite the same. This review will summarize both the pre-clinical and clinical studies evaluating these associations.

Exosomes Derived From Natural Killer Cells Exert Therapeutic Effect in Melanoma

Objective: Exosomes are nanovesicles that are released from normal and tumor cells and are detectable in cell culture supernatant and human biological fluids. Although previous studies have explored exosomes released from cancer cells, little is understood regarding the functions of exosomes released by normal cells. Natural killer (NK) cells display rapid immunity to metastatic or hematological malignancies, and efforts have been undertaken to clinically exploit the antitumor properties of NK cells. However, the characteristics and functions of exosomes derived from NK cells remain unknown. In this study, we explored NK cell-derived exosome-mediated antitumor effects against aggressive melanoma in vitro and in vivo. Methods: B16F10 cells were transfected with enhanced firefly luciferase (effluc) and thy1.1 genes, and thy1.1-positive cells were immunoselected using microbeads. The resulting B16F10/effluc cells were characterized using reverse transcriptase polymerase chain reaction (RT-PCR), western blotting, and luciferase activity assays. Exosomes derived from NK-92MI cells (NK-92 Exo) were isolated by ultracentrifugation and density gradient ultracentrifugation. NK-92 Exo were characterized by transmission electron microscopy and western blotting. We also performed an enzyme-linked immunosorbent assay to measure cytokines retained in NK-92 Exo cells. The in vitro cytotoxicity of NK-92 Exo against the cancer cells was determined using a bioluminescence imaging system (BLI) and CCK-8 assays. To investigate the possible side effects of NK-92 Exo on healthy cells, we also performed the BLI and CCK-8 assays using the human kidney Phoenix™-Ampho cell line. Flow cytometry and western blotting confirmed that NK-92 Exo induced apoptosis in the B16F10/effluc cells. In vivo, we used a B16F10/effluc cell xenograft model to detect the immunotherapeutic effect of NK-92 Exo. We injected NK-92 Exo into tumors, and tumor growth progression was monitored using the IVIS Lumina imaging system and ultrasound imaging. Tumor mass was monitored after in vivo experiments. Results: RT-PCR and western blotting confirmed effluc gene expression and protein levels in B16F10/effluc cells. B16F10/effluc activity was found to increase with increasing cell numbers, using BLI assay. For NK-92 Exo characterization, western blotting was performed on both ultracentrifuged and density gradient-isolated exosomes. The results confirmed that NK cell-derived exosomes express two typical exosome proteins, namely CD63 and ALIX. We demonstrated by western blot analysis that NK-92 Exo presented two functional NK proteins, namely perforin and FasL. Moreover, we confirmed the membrane expression of FasL. The enzyme-linked immunosorbent assay results indicated that NK-92 Exo can secrete tumor necrosis factor (TNF)-α, which affected the cell proliferation signaling pathway. The antitumor effect of NK-92 Exo against B16F10/effluc cells in vitro was confirmed by BLI (p < 0.001) and CCK-8 assays (p < 0.001). Furthermore, in normal healthy cells, even after 24 h of co-culture, NK-92 Exo did not exhibit significant side effects. In the in vivo experiments, tumors in the vehicle control group were significantly increased, compared with those in the NK-92 Exo-treated group (p < 0.05). Conclusion: The results of the current study suggest that exosomes derived from NK cells exert cytotoxic effects on melanoma cells and thus warrant further development as a potential immunotherapeutic strategy for cancer.

A Refined Bead-Free Method to Identify Astrocytic Exosomes in Primary Glial Cultures and Blood Plasma

Astrocytes are the most abundant glial cell type in the central nervous system (CNS) and are known to fulfill critical homeostatic functions. Dysfunction of activated astrocytes is also known to participate in the development of several neurological diseases. Astrocytes can be uniquely identified by expression of the intermediate filament protein glial acidic fibrillary protein (GFAP). Herein, we report on the development of a rigorous and sensitive methodology to identify GFAP+ exosomes in primary culture using flow cytometry. We then demonstrate that activated astrocytes release increased amounts of exosomes in response to treatment with interleukin-1β. Using this methodology, we report the identification of GFAP+ exosomes in blood and then use a mouse model of inflammatory demyelination, experimental autoimmune encephalomyelitis (EAE), to examine whether the abundance of GFAP+ exosomes in blood circulation changes during clinical illness. We find a detectable increase in the presence of GFAP+ exosomes in EAE mice when compared with non-EAE, control mice. Our data provide a novel perspective on the presence of GFAP in blood as it identifies exosomes as potential astrocyte-derived signals within blood. These data are complementary to previous clinical studies that reported elevated GFAP protein in blood samples from multiple sclerosis (MS) patients during a clinical relapse. These data also reveal the existence of a potential systemic role for astrocyte-derived exosomes in CNS conditions involving inflammation such as multiple sclerosis.

Transfusion-related immunomodulation and cancer

Blood and blood-component therapy triggers immunological reactions in recipients. Transfusion-related immunomodulation [TRIM] is an important complex biological immune reaction to transfusion culminating in immunosuppression. The mechanisms underlying TRIM include the presence of residual leukocytes and apoptotic cells, the transfusion of immunosuppressive cytokines either present in donor components or generated during blood processing, the transfer of metabolically active growth factor-loaded microparticles and extracellular vesicles and the presence of free hemoglobin or extracellular vesicle-bound hemoglobin. TRIM variables include donor-specific factors as well as processing variables. TRIM may explain, at least in part, the controversial negative clinical outcomes observed in cancer patients receiving transfusion in the context of curative-intent surgeries. The use of novel technologies including metabolomics and proteomics on stored blood may pave the way for a deeper understanding of TRIM in general and its impact on cancer progression.

Red blood cell transfusion in surgical cancer patients: Targets, risks, mechanistic understanding and further therapeutic opportunities

Anemia is present in more than half of cancer patients and appears to be an independent prognostic factor of short- and long-term adverse outcomes. It increases in the advanced period of cancer and perioperatively, in patients with solid tumors who undergo surgery. As a result, allogeneic red blood cell (RBC) transfusion is an indispensable treatment in cancer. However, its safety remains controversial, based on several laboratory and clinical data reporting a linkage with increased risk for cancer recurrence, infection and cancer-related mortality. Immunological, inflammatory and thrombotic reactions mediated by the residual leukocytes and platelets, the stored RBCs per se, the biological response modifiers and the plasticizer of the unit may underlie infection and tumor-promoting effects. Although the causality between transfusion and infection has been established, the effects of transfusion on cancer recurrence remain confusing; this is mainly due to the extreme biological heterogeneity that characterizes RBC donations and cancer context. In fact, the functional interplay between donation-associated factors and recipient characteristics, including tumor biology per se, inflammation, infection, coagulation and immune activation state and competence may synergistically and individually define the clinical impact of each transfusion in any given cancer patient. Our understanding of how the potential risk is mediated is important to make RBC transfusion safer and to pave the way for novel, promising and highly personalized strategies for the treatment of anemia in surgical cancer patients.

Influence of red blood cell-derived microparticles upon vasoregulation

Here we review recent data and the evolving understanding of the role of red blood cell-derived microparticles (RMPs) in normal physiology and in disease progression. Microparticles (MPs) are small membrane vesicles derived from various parent cell types. MPs are produced in response to a variety of stimuli through several cytoskeletal and membrane phospholipid changes. MPs have been investigated as potential biomarkers for multiple disease processes and are thought to have biological effects, most notably in: promotion of coagulation, production and handling of reactive oxygen species, immune modulation, angiogenesis, and in apoptosis. Specifically, RMPs are produced normally during RBC maturation and their production is accelerated during processing and storage for transfusion. 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 from that of intact RBCs, and the nature and composition of RMP components are affected by both storage duration and the character of storage solutions. Recognised RMP bioactivities include: promotion of coagulation, immune modulation, and promotion of endothelial adhesion, as well as influence upon vasoregulation via nitric oxide (NO) scavenging. Of particular relevance, RMPs are more avid NO scavengers than intact RBCs and this feature has been proposed as a mechanism for the impaired oxygen delivery homeostasis that has been observed following transfusion. Preliminary human studies demonstrate that circulating RMP abundance increases with RBC transfusion and is associated with altered plasma vasoactivity and abnormal vasoregulation. In summary, RMPs are submicron particles released from stored RBCs, with demonstrated vasoactive properties that appear to disturb oxygen delivery homeostasis. The clinical impact of RMPs in transfusion recipients is an area of continued investigation.

Plasma-derived exosomes contribute to inflammation via the TLR9-NF-κB pathway in chronic heart failure patients

Exosomes are small vesicles that contain proteins, DNA and RNA, and play an important role in inflammation; however, the underlying mechanism remains unclear. In the present study, we found increased plasma-derived exosomes in chronic heart failure patients compared with healthy controls. Further, our data demonstrated that plasma-derived exosomes carried mtDNA, and triggered an inflammatory response via the TLR9-NF-κB pathway, as well, the inflammatory effect was closely related to exosomal mtDNA copy number. However, the effect could be blocked by chloroquine (CQ), a TLR9 inhibitor. These findings reveal a new mechanism of exosome-induced inflammation, and provide a new perspective for intervention and treatment of inflammation-related diseases, such as chronic heart failure.

Cumulative erythrocyte damage in blood storage and relevance to massive transfusions: selective insights into serial morphological and biochemical findings

Elucidating the precise mechanisms of cumulative red cell damages during storage and the potential harmful consequences after transfusion are achievable by exacting laboratory science and well-defined clinical studies in progress. Accordingly, for larger magnitude blood transfusions (i.e. 8-12 U in 24 hours), the quality of the stored blood and its characterisation are of special academic and clinical importance. Our main objectives in this review are to illuminate facets of the red cell storage lesion for prolonged storage (0-42 days) by concentrating on various hallmarks of the disorder: 1) identifying and characterising serial markers of the progressive lesion with respect to red cell dysmorphology, deformability, haemolytic fragility and dysfunction both in storage and the microcirculation; and 2) relevant biochemical findings of redox status correlated to oxidative stress of erythrocyte proteins. This is accomplished in part by reliance on advanced metabolomic and proteomic technologies using various sophisticated tools such as high pressure liquid chromatography in combination with mass spectrometry of proteins and small molecule metabolites. It is anticipated that these sophisticated methodologies and the experimental results therein shall lead to further advances in the quality improvement of red cell storage.

Uptake of lymphoma-derived exosomes by peripheral blood leukocytes

Exosomes are nanosized lipid vesicles secreted into blood and other body fluids and serve as vehicles for intercellular communication. Despite being an important component of the tumor microenvironment (TME), exosomal targeting and uptake into recipient cells are still not fully understood. Few studies have looked at lymphoma exosomes and their interactions with circulating blood cells. In this study, we examine the exosomal uptake distribution among peripheral blood leukocytes (PBLs) using vesicles derived from a diffuse large B cell lymphoma cell line, WSU-DLCL2. Lymphoma cells survive, proliferate, and are protected from the cytotoxic effects of chemotherapeutic agents by soluble factors or by direct contact with inflammatory and stromal cells within the TME. In an attempt to close the gap in knowledge concerning lymphoma TME immunosuppression, we have treated normal human PBLs with PKH67-labeled lymphoma exosomes and monitored the uptake by measuring fluorescence at different time points using flow cytometry and fluorescent microscopy. Our results show that of the four populations examined, B cells and monocytes demonstrated uptake of PKH67-labeled exosomes, while T cells and NK cells displayed significantly less uptake.

Potential role of corneal epithelial cell-derived exosomes in corneal wound healing and neovascularization

Specific factors from the corneal epithelium underlying the stimulation of stromal fibrosis and myofibroblast formation in corneal wound healing have not been fully elucidated. Given that exosomes are known to transfer bioactive molecules among cells and play crucial roles in wound healing, angiogenesis, and cancer, we hypothesized that corneal epithelial cell-derived exosomes may gain access to the underlying stromal fibroblasts upon disruption of the epithelial basement membrane and that they induce signaling events essential for corneal wound healing. In the present study, exosome-like vesicles were observed between corneal epithelial cells and the stroma during wound healing after corneal epithelial debridement. These vesicles were also found in the stroma following anterior stromal keratectomy, in which surgical removal of the epithelium, basement membrane, and anterior stroma was performed. Exosomes secreted by mouse corneal epithelial cells were found to fuse to keratocytes in vitro and to induce myofibroblast transformation. In addition, epithelial cell-derived exosomes induced endothelial cell proliferation and ex vivo aortic ring sprouting. Our results indicate that epithelial cell-derived exosomes mediate communication between corneal epithelial cells and corneal keratocytes as well as vascular endothelial cells. These findings demonstrate that epithelial-derived exosomes may be involved in corneal wound healing and neovascularization, and thus, may serve as targets for potential therapeutic interventions.

Current Perspectives on In Vivo Noninvasive Tracking of Extracellular Vesicles with Molecular Imaging

Clinical and preclinical in vivo tracking of extracellular vesicles (EVs) are a crucial tool for the development and optimization of EV-based diagnosis and treatment. EVs have gained interest due to their unique properties that make them excellent candidates for biological applications. Noninvasive in vivo EV tracking has allowed marked progress towards elucidating the mechanisms and functions of EVs in real time in preclinical and clinical studies. In this review, we summarize several molecular imaging methods that deal with EVs derived from different cells, which have allowed investigations of EV biodistribution, as well as their tracking, delivery, and tumor targeting, to determine their physiological functions and to exploit imaging-derived information for EV-based theranostics.

Insights into red blood cell storage lesion: Toward a new appreciation

Red blood cell storage lesion (RSL) is a multifaceted biological phenomenon. It refers to deterioration in RBC quality that is characterized by lethal and sub-lethal, reversible and irreversible defects. RSL is influenced by prestorage variables and it might be associated with variable clinical outcomes. Optimal biopreservation conditions are expected to offer maximum levels of RBC survival and acceptable functionality and bioreactivity in-bag and in vivo; consequently, full appraisal of RSL requires understanding of how RSL changes interact with each other and with the recipient. Recent technological innovation in MS-based omics, imaging, cytometry, small particle and systems biology has offered better understanding of RSL contributing factors and effects. A number of elegant in vivo and in vitro studies have paved the way for the identification of quality control biomarkers useful to predict RSL profile and posttransfusion performance. Moreover, screening tools for the early detection of good or poor "storers" and donors have been developed. In the light of new perspectives, storage time is not the touchstone to rule on the quality of a packed RBC unit. At least by a biochemical standpoint, the metabolic aging pattern during storage may not correspond to the currently fresh/old distinction of stored RBCs. Finally, although each unit of RBCs is probably unique, a metabolic signature of RSL across storage variables might exist. Moving forward from traditional hematologic measures to integrated information on structure, composition, biochemistry and interactions collected in bag and in vivo will allow identification of points for intervention in a transfusion meaningful context.

Reduction of biological response modifiers in the supernatant of washed paediatric red blood cells

BACKGROUND

Washing of red blood cells (RBC) can reduce unwanted biological response modifiers (BRMs) that can mediate transfusion complications in infants. The aim of this study was to examine the in vitro quality and the changes in BRMs following washing in paediatric RBC units.

MATERIALS AND METHODS

A pool and split design was used to prepare RBC (either 1 or 4 days old; n = 26 pairs). One unit was washed with 0·9% saline by centrifugation and then resuspended in SAG-M, while the other remained unwashed. Each RBC unit was divided to produce four units of paediatric-sized components. Samples were taken after 3 h and subsequently on days 1, 2, 7 and 14 post-wash.

RESULTS

Washing of RBC resulted in some red cell loss, with a minor increase in haemolysis. Washing effectively reduced supernatant potassium and IgA, as well as cytokines and complement proteins. RBC microparticles were significantly reduced in RBC washed at 1, but not 4 days post-collection. Incubation with supernatant from unwashed but not washed RBC led to endothelial cell activation, with increased cell surface expression of CD62E (E-selectin) and CD106 (VCAM).

CONCLUSION

Although washing affected some aspects of the in vitro quality of RBC, it effectively reduced the concentration and activity of BRMs in the supernatant of RBC. Such a reduction may be clinically beneficial in selected patient groups.

Antigen Presentation in Transplantation

Transplantation of solid organs between genetically distinct individuals leads, in the absence of immunosuppression, to T cell-dependent transplant rejection. Activation of graft-reactive T cells relies on the presentation of transplant-derived antigens (intact donor MHC molecules or processed peptides on host MHC molecules) by mature dendritic cells (DCs). This review focuses on novel insights regarding the steps for maturation and differentiation of DCs that are necessary for productive presentation of transplant antigens to host T cells. These steps include the licensing of DCs by the microbiota, their activation and maturation following recognition of allogeneic non-self, and their capture of donor cell exosomes to amplify the presentation of transplant antigens.

Circulating MicroRNAs in Graves' Disease in Relation to Clinical Activity

BACKGROUND

Understanding the roles of circulating microRNAs (miRNAs) can provide important and novel information regarding disease pathogenesis and a patient's clinical condition. Circulating miRNAs, such as exosomal miRNA, may regulate various bioactivities related to intercellular communication. However, the circulation of miRNAs in Graves' disease (GD) in relation to disease activity has never been elucidated. This study aimed to identify circulating miRNAs in GD in relation to disease activity and whether their exosomes play a role in the pathogenesis of GD.

METHODS

Circulating miRNAs were measured in serum obtained from seven intractable GD patients, seven GD patients in remission, and seven healthy controls using the miScript miRNA PCR Array. Altered miRNAs selected from array data were validated in 65 subjects. To investigate exosome biology, peripheral blood mononuclear cells (PBMCs) were incubated with exosomes isolated from the subjects' sera. mRNAs were quantified for cytokines using quantitative real-time polymerase chain reaction.

RESULTS

Circulating miR-23b-5p and miR-92a-39 were increased in GD patients in remission compared with intractable GD patients (p < 0.05). On the other hand, let-7g-3p and miR-339-5p were decreased in GD patients in remission compared with intractable GD patients (p < 0.05). Exosomes from intractable GD patients stimulated mRNA expression for IL-1β and TNF-α compared with GD patients in remission or healthy controls.

CONCLUSIONS

This study demonstrates that different levels of circulating miRNAs are associated with intractable GD. Moreover, serum exosomes of patients with intractable GD may activate immune cells, which may play an important role in GD pathogenesis.