Transfusion-related immunomodulation due to peripheral blood dendritic cells expressing the CD200 tolerance signaling molecule and alloantigen

The potential mechanisms of extracellular vesicles in transfusion-related adverse reactions: Recent advances

Blood transfusion is an irreplaceable clinical treatment. Blood components are differentiated and stored according to specific guidelines. Storage temperatures and times vary depending on the blood component, but they all release extracellular vesicles (EVs) during storage. Although blood transfusions can be life-saving, they can also cause many adverse transfusion reactions, among which the effects of EVs are of increasing interest to researchers. EVs are submicron particles that vary in size, composition, and surface biomarkers, are encapsulated by a lipid bilayer, and are not capable of self-replication. EVs released by blood cells are important contributors to pathophysiologic states through proinflammatory, coagulant, and immunosuppressive effects, which in turn promote or inhibit the associated disease phenotype. Therefore, this review explores the potential mechanisms of hematopoietic-derived EVs in transfusion-associated adverse reactions and discusses the potential of the latest proteomics tools to be applied to the analysis of EVs in the field of transfusion medicine with a view to reducing the risk of blood transfusion.

Transfusion Trends of Knee Arthroplasty in Korea: A Nationwide Study Using the Korean National Health Insurance Service Sample Data

Knee arthroplasties are strongly associated with blood transfusion to compensate for perioperative bleeding. The purpose of this study was to evaluate trends of transfusion associated with knee arthroplasties using nationwide data of the National Health Insurance Service-National Sample Cohort (NHIS-NSC). Using data from the nationwide claims database of the Health Insurance Review Assessment Service managed by the NHIS, 50,553 knee arthroplasties under three categories (total knee replacement arthroplasty, uni-knee replacement arthroplasty, and revision arthroplasty) from 2012 to 2018 were identified. Overall transfusion rate, transfusion count, proportion of each type of transfusion, and cost associated with each type of operation were investigated. Overall transfusion rate was 83.4% (5897/7066) in 2012, 82.7% (5793/7001) in 2013, 79.6% (5557/6978) in 2014, 75.9% (5742/7557) in 2015, 73.1% (6095/8337) in 2016, 68.2% (4187/6139) in 2017, and 64.6% (4271/6613) in 2018. The proportion of each type of transfusion was 1.8% for fresh frozen plasma, 0.5% for platelets, and 97.7% for red blood cells. The average cost of transfusion was $109.1 ($123 in 2012, $124 in 2013, $123.3 in 2014, $110.6 in 2015, $100 in 2016, $92.9 in 2017, and $90.1 in 2018). In this nationally representative study of trends in transfusion associated with knee arthroplasty, we observed significantly high rates of blood transfusion among patients undergoing knee arthroplasties. Although the overall rate of transfusion had declined, the allogeneic transfusion rate was still high from 2012 to 2018 in Korea. Thus, surgeons need to develop various patient blood management plans and minimize the use of allogeneic transfusion when performing knee arthroplasties.

Big data analysis of the risk factors and rates of perioperative transfusion in immediate autologous breast reconstruction

Patients undergoing autologous breast reconstruction (ABR) are more likely to require perioperative transfusions due to the increased intraoperative bleeding. In addition to the mastectomy site, further incisions and muscle dissection are performed at the donor sites, including the back or abdomen, increasing the possibility of transfusion. The purpose of this study was to evaluate perioperative transfusion rates and risk factors according to the type of ABR through analysis of big data. Patients who underwent total mastectomy for breast cancer between 2014 and 2019 were identified. The patients were divided into mastectomy only and immediate ABR groups. The transfusion rate was 14-fold higher in the immediate ABR group (16.1%) compared to the mastectomy only group (1.2%). The transfusion rate was highest with the pedicled transverse rectus abdominis myocutaneous flap (24.2%). Performance of the operation in medical institutions located in the provinces and coronary artery disease (CAD) were significant risk factors for the need for transfusion. The perioperative transfusion risk among patients undergoing immediate ABR was related to the flap type, location of medical institution, and CAD. Based on the higher transfusion rate in this study (16.1%) compared to previous studies, the risk factors for the need for transfusion should be determined and evidence-based guidelines should be developed to reduce the transfusion rates.

Transfusion‑related immunomodulation in patients with cancer: Focus on the impact of extracellular vesicles from stored red blood cells (Review)

Red blood cell (RBC) transfusions may have a negative impact on the prognosis of patients with cancer, where transfusion‑related immunomodulation (TRIM) may be a significant contributing factor. A number of components have been indicated to be associated with TRIM. Among these, the impact of extracellular vesicles (EVs) has been garnering increasing attention from researchers. EVs are defined as nano‑scale, cell‑derived vesicles that carry a variety of bioactive molecules, including proteins, nucleic acids and lipids, to mediate cell‑to‑cell communication and exert immunoregulatory functions. RBCs in storage constitutively secrete EVs, which serve an important role in TRIM in patients with cancer receiving a blood transfusion. Therefore, the present review aimed to first summarize the available information on the biogenesis and characterization of EVs. Subsequently, the possible mechanisms of TRIM in patients with cancer and the impact of EVs on TRIM were discussed, aiming to provide an outlook for future studies, specifically for formulating recommendations for managing patients with cancer receiving RBC transfusions.

Association of CD200 expression in paternal lymphocytes with female Th1/Th2 balance and pregnancy establishment at immunotherapy of recurrent spontaneous abortion

PROBLEM

We hypothesized that expression of transmembrane glycoprotein CD200 on paternal lymphocytes used for pre-gestational lymphocyte immunotherapy (LIT) of recurrent spontaneous abortion (RSA) can suppress the pro-inflammatory Th1-type immunity required for successful implantation. To reveal the association between CD200 expression, female immune background after LIT, and pregnancy establishment, we have performed this work.

METHOD OF STUDY

Pre-gestational alloimmunizations were given to 37 women using paternal peripheral blood leukocytes, combined with additional alloimmunizations in case of pregnancy. Lymphocyte phenotypes were determined by flow cytometry. Cytokines produced by mitogen-stimulated female peripheral blood cells were estimated by FlowCytomix™ technology.

RESULTS

We have shown that 78.4% (29/37) of women became pregnant within 12 menstrual cycles after pre-gestational LIT. Pregnancy establishment depends on the intensity of CD200 expression, which is significantly higher on the CD200⁺ lymphocytes administered to women who later did not achieve pregnancy (P < .05). The expression of CD200 negatively correlates with the ratios of Th1/Th2 cytokines produced by female peripheral blood cells (P < .05) and positively correlates with the frequency of female circulating regulatory T cells after LIT (P < .05). The ROC analysis showed that the intensity of CD200 expression and the Th1/Th2 ratios are the significant predictors of pregnancy establishment after pre-gestational LIT (P < .05 and P < .01, respectively).

CONCLUSION

Elevated CD200 expression on allogeneic lymphocytes most likely suppresses the pro-inflammatory Th1-type immunity needed for successful embryo implantation. Therefore, a personalized approach of LIT should be applied to avoid negative effects of such immunomodulation on pregnancy establishment.

The role of extracellular vesicles from stored RBC units in B lymphocyte survival and plasma cell differentiation

Extracellular vesicles (EVs) are small, double-membrane vesicles derived from erythrocytes, leukocytes, platelets, and cells of multiple tissues under physiologic or pathologic conditions. The role of EVs in stored RBC units is of great interest with respect to transfusion-related immunomodulation. The current study focuses on the quantity of EVs isolated from stored RBC units and their action on B cell-mediated immune responses. The in vitro experiment demonstrated that EVs exhibited a negative role in B cell survival, plasmacytic differentiation, and class switch recombination under LPS stimulation. Furthermore, LPS-induced antibody production was significantly decreased after EVs injection in vivo. Biochemical analysis revealed that EVs hampered the expression of Blimp-1 and IRF4 and the activation of NF-κB pathway in LPS-primed B cells. Overall, these data imply a vital role for EVs isolated from RBC units in B cell-mediated immune responses.

Implications of perioperative allogeneic red blood cell transfusion on the immune-inflammatory response

Background

The allogeneic transfusion-related immunomodulation (TRIM) may be responsible for an increase in survival of renal transplants but in contrast it could increase the rate of bacterial infections or the recurrence rate of tumors post-operatively.

Objective

This review focuses in the implications of perioperative allogeneic transfusions on the immune-inflammatory response of surgical transfused patients.

Results

ABTs modify immune functions in recipients including decrease of the number of lymphocytes; decrease the CD4 cells; decrease the CD4/CD8 T-cell ratio; decrease NK cells; and decrease the lymphocyte response to mitogens. TRIM effects may be mediated by allogeneic white cells present in blood products; soluble peptides present in transfused plasma; and/or biologic mediators released into the supernatant of blood units. A recent systematic review and meta-analysis including 36 clinical observational studies (n = 174,036) concluded that perioperative ABTs not only decreased overall survival and reduced colorectal cancer-specific survival. Furthermore ABTs increased the rate of infectious, cardiac, pulmonary and anastomotic complications in colorectal cancer patients undergoing surgery.

Conclusions

It has been demonstrated by laboratory tests that TRIM is associated with transfusion recipient immune alterations but its influence in colorectal cancer recurrence after resection remains controversial though may exist. Surgical techniques reducing intraoperative blood loss have limited the number of ABTs perioperatively, however increase in mortality continues to be reported in literature after ABT in colorectal cancer surgery. Poor survival associated to TRIM in colorectal cancer might be due to higher number of allogeneic transfused units and/or prolonged length of blood storage.

Packed Red Blood Cell Transfusion Modulates Myeloid Dendritic Cell Activation and Inflammatory Response In Vitro

Transfusion of packed red blood cells (PRBCs) modulates patients' immune responses and clinical outcomes; however, the underpinning mechanism(s) remain unknown. The potential for PRBC to modulate myeloid dendritic cells (mDC) and blood DC antigen 3 was assessed using an in vitro transfusion model. In parallel, to model processes activated by viral or bacterial infection, toll-like receptor agonists polyinosinic:polycytidylic acid or lipopolysaccharide were added. Exposure to PRBC upregulated expression of CD83 and downregulated CD40 and CD80 on both DC subsets, and it suppressed production of interleukin (IL)-6, IL-8, IL-12, tumor necrosis factor-α, and interferon-gamma-inducible protein-10 by these cells. Similar effects were observed when modeling processes activated by concurrent infection. Furthermore, exposure to PRBC at date of expiry was associated with more pronounced effects in all assays. Our study suggests PRBC have an impact on recipient DC function, which may result in failure to establish an appropriate immune response, particularly in patients with underlying infection.

Pre-transplant CD200 and CD200R1 concentrations are associated with post-transplant events in kidney transplant recipients

CD200 is an immunoglobulin superfamily membrane protein that binds to a myeloid cell-specific receptor and induces inhibitory signaling. The aim of this study was to investigate the role of CD200 and its receptor (CD200R1) on kidney transplant (KTx) outcome. In a collective of 125 kidney recipients (University hospital, Heidelberg, Germany), CD200 and CD200R1 concentrations were evaluated immediately before transplantation. Recipient baseline and clinical characteristics and KTx outcome, including acute rejection (AR), acute tubular necrosis, delayed graft function, cytomegalovirus (CMV) and human polyomaviridae (BK) virus infections, and graft loss were evaluated during the first post-transplant year. The association of CD200 and CD200R1 concentrations and CD200R1/CD200 ratios with the outcome of KTx was investigated for the first time in a clinical setting in a prospective cohort. There was a positive association between pre-transplant CD200R1 concentrations and CMV (re)activation (P = .041). Also, increased CD200R1 concentration was associated with a longer duration of CMV infection (P = .049). Both the frequency of AR and levels of creatinine (3 and 6 months after KTx) were significantly higher in patients with an increased CD200R1/CD200 ratio (median: 126 vs 78, P = .008). Increased pre-transplant CD200R1/CD200 ratios predict immunocompetence and risk of AR, whereas high CD200R1 concentrations predict immunosuppression and high risk of severe CMV (re)activation after KTx.

Transfusion trends in hip arthroplasty in Korea: a nationwide study by the Korean National Health Insurance Service

BACKGROUND

Hip arthroplasties are strongly associated with blood transfusion to compensate for perioperative bleeding. The purpose of this study was to evaluate the trends in transfusion associated with hip arthroplasties, using nationwide data supplied by the National Health Insurance Service.

STUDY DESIGN AND METHODS

We used data from nationwide claims database of the Health Insurance Review Assessment Service. The data managed by the National Health Insurance Service were used to identify 161,934 hip arthroplasties under three categories, including bipolar hemiarthroplasty, total hip arthroplasty, and revision arthroplasty, from 2007 to 2015. The transfusion rates, transfusion amounts, the proportion of transfusion, and cost associated with each type of operation were investigated and stratified according to age, sex, hospital type, and region.

RESULTS

The proportion of patients receiving any allogeneic transfusion was 81.1% in 9 years. The overall proportion of transfusion was 7% fresh frozen plasma, 12% platelets, and 77% RBCs. The average count of transfusions was 4.1 in bipolar hemiarthroplasty (343,815/83,729), 4.3 in total hip arthroplasty (196,869/46,097), and 8.7 in revision arthroplasty (35,044/4,024) from 2007 to 2015.

CONCLUSION

In this nationally representative study of trends in transfusion associated with hip arthroplasty, we observed significantly high rates of blood transfusion among patients undergoing hip arthroplasties. Although the overall amount of transfusion declined, the allogeneic transfusion rate was still high from 2007 to 2015 in Korea, and higher than other countries are reporting.

Immunomodulatory Effects of Blood Transfusion on Tumor Size, Metastasis, and Survival in Experimental Fibrosarcoma

In spite of efforts, blood transfusion is still accompanied with adverse effects such as transfusion-related immunomodulation (TRIM). The current study aimed to evaluate the effects of allogeneic, syngeneic, fresh and storage blood transfusion on the growth and metastasis of tumors and survival in fibrosarcoma bearing BALB/c mice. Twenty-five BALB/c mice were grouped into five groups of equal size. All groups were injected 1.2 × 10⁶ WEHI-164 cells subcutaneously to induce fibrosarcoma tumor. After expansion of the tumor, in four groups (except for the control group), hemorrhage-induced anemia was developed. Twenty-four hours later, blood deficit was replaced by fresh allogeneic, storage allogeneic, fresh syngeneic and storage syngeneic blood transfusion, respectively. After a blood transfusion, for 13 days, the tumor size and survival of the mice were evaluated. In the day 20, the mice were sacrificed and their spleen tissues were evaluated for TRIM induced metastasis. Tumor size increase in the groups that received allogeneic (fresh and storage) and storage syngeneic blood transfusion was significantly higher than the control group (P value < 0.05). However, no significant difference was present in survival between the experiment groups and the control group. There was no metastasis in none of groups at the end of the study. Allogeneic and storage blood transfusion could have immunomodulatory effects such as increased tumor size. However, it seems that fresh and syngeneic blood transfusion have no effects on tumor growth in fibrosarcoma bearing mice. Further evidence may prove that more attention is warranted in blood transfusion into cancer cases.

Effect of storage period of red blood cell suspensions on helper T-cell subpopulations

BACKGROUND

The aim of this study was to investigate the immunological alterations that occur during the storage of erythrocyte suspensions which may lead to transfusion-related immunomodulation following allogeneic blood transfusion.

MATERIALS AND METHODS

One part of the erythrocyte suspensions obtained from donors was leucoreduced while the other part was not. The leucoreduced (LR) and non-leucoreduced (NL) erythrocyte suspensions were then further divided into three equal amounts which were stored for 0, 21 or 42 days prior to measurements, by enzyme-linked immunosorbent assays, of cytokine levels in their supernatants. T-helper (Th) lymphocyte subgroups and gene expression were analysed in the NL erythrocyte suspensions by flow cytometry and real-time polymerase chain reaction, respectively. Results were compared to those of storage day 0.

RESULTS

By day 21, the number of Th2 cells had increased significantly and the numbers of Th1, Th22 and Treg cells had decreased significantly in the NL erythrocyte suspensions. On day 42 the numbers of Th2 and Treg cells in the NL suspensions were significantly increased while the number of Th1 cells was significantly decreased. The levels of transcription factors (TBX21, GATA3, and SPI.1) were significantly decreased on days 21 and 42, and AHR, FOXP3 and RORC2 levels were significantly increased on day 42 in NL erythrocyte suspensions. The decrease in interleukin-22 and increase in transforming growth factor-β levels found in NL erythrocyte suspensions on day 21 were statistically significant. Elevated levels of interleukin-17A were found in both LR and NL erythrocyte suspensions on day 42.

DISCUSSION

Our results suggest that allogeneic leucocytes and cytokines may play significant roles in the development of transfusion-related immunomodulation.

Perioperative Blood Transfusion and Postoperative Outcome in Patients with Crohn's Disease Undergoing Primary Ileocolonic Resection in the "Biological Era"

BACKGROUND

Perioperative blood transfusion has been shown to be associated with inflammatory response and immunosuppression. Patients receiving blood transfusion may have an increased risk for developing postoperative morbidities. The impact of blood transfusion on the postoperative recurrence of Crohn's disease (CD) has been controversial. The aim of this study was to assess the effect of blood transfusion on postoperative outcomes in CD in the current biological era.

METHODS

This historical cohort study involved data collection and analysis of CD patients who underwent the index ileocolonic resection in our institution between 2000 and 2012. Postoperative complications were compared between the transfused and nontransfused patients. The effects of perioperative blood transfusion on postoperative complications and disease recurrence were analyzed with both univariate and multivariate analyses.

RESULTS

A total of 318 patients were included in the study, and 52 of them (16.5 %) received perioperative blood transfusion. Blood transfusion was found to be associated with an increased risk of postoperative infectious and noninfectious complications both in univariate (P < 0.001 for each) and multivariable analyses (infectious complications: odds ratio [OR] = 8.73, 95 % confidence interval [CI] 2.85-26.78, P < 0.001; noninfectious complications: OR = 3.64, 95 % CI 1.30-10.18; P = 0.014). In addition, the Cox regression model indicated that blood transfusion was associated with both surgical (hazard ratio [HR] = 3.43, 95 % CI 1.92-6.13; P < 0.001) and endoscopic (HR = 2.08, 95 % CI 1.38-3.14; P < 0.001) CD recurrence following the index surgery.

CONCLUSION

Adverse outcomes after perioperative blood transfusion for the primary ileocolonic resection for CD resemble findings in surgery for other diseases. The presumed immunosuppressive effect of blood transfusion did not confer any protective effect on disease recurrence.

Liberal versus restrictive blood transfusion strategy: 3-year survival and cause of death results from the FOCUS randomised controlled trial

BACKGROUND

Blood transfusion might affect long-term mortality by changing immune function and thus potentially increasing the risk of subsequent infections and cancer recurrence. Compared with a restrictive transfusion strategy, a more liberal strategy could reduce cardiac complications by lowering myocardial damage, thereby reducing future deaths from cardiovascular disease. We aimed to establish the effect of a liberal transfusion strategy on long-term survival compared with a restrictive transfusion strategy.

METHODS

In the randomised controlled FOCUS trial, adult patients aged 50 years and older, with a history of or risk factors for cardiovascular disease, and with postoperative haemoglobin concentrations lower than 100 g/L within 3 days of surgery to repair a hip fracture, were eligible for enrolment. Patients were recruited from 47 participating hospitals in the USA and Canada, and eligible participants were randomly allocated in a 1:1 ratio by a central telephone system to either liberal transfusion in which they received blood transfusion to maintain haemoglobin level at 100 g/L or higher, or restrictive transfusion in which they received blood transfusion when haemoglobin level was lower than 80 g/L or if they had symptoms of anaemia. In this study, we analysed the long-term mortality of patients assigned to the two transfusion strategies, which was a secondary outcome of the FOCUS trial. Long-term mortality was established by linking the study participants to national death registries in the USA and Canada. Treatment assignment was not masked, but investigators who ascertained mortality and cause of death were masked to group assignment. Analyses were by intention to treat. The FOCUS trial is registered with ClinicalTrials.gov, number NCT00071032.

FINDINGS

Between July 19, 2004, and Feb 28, 2009, 2016 patients were enrolled and randomly assigned to the two treatment groups: 1007 to the liberal transfusion strategy and 1009 to the restrictive transfusion strategy. The median duration of follow-up was 3·1 years (IQR 2·4-4·1 years), during which 841 (42%) patients died. Long-term mortality did not differ significantly between the liberal transfusion strategy (432 deaths) and the restrictive transfusion strategy (409 deaths) (hazard ratio 1·09 [95% CI 0·95-1·25]; p=0·21).

INTERPRETATION

Liberal blood transfusion did not affect mortality compared with a restrictive transfusion strategy in a high-risk group of elderly patients with underlying cardiovascular disease or risk factors. The underlying causes of death did not differ between the trial groups. These findings do not support hypotheses that blood transfusion leads to long-term immunosuppression that is severe enough to affect long-term mortality rate by more than 20-25% or cause of death.

FUNDING

National Heart, Lung, and Blood Institute.

Association of perioperative blood transfusion and adverse events after operative treatment of proximal humerus fractures

BACKGROUND

The purpose of this study was to assess the relationship between perioperative blood transfusion for proximal humerus fracture and inpatient mortality, adverse events, prolonged hospital stay, and nonroutine disposition.

METHODS

Among the >55,000 patients with an operatively treated proximal humerus fracture identified in the Nationwide Inpatient Sample between 2008 and 2011, 17% received a perioperative blood transfusion. Multivariable logistic regression analyses addressed the association of blood transfusion with inpatient mortality, adverse events, hospital stay, and nonroutine discharge, accounting for comorbidities and other known confounders.

RESULTS

Perioperative blood transfusion for fracture of the proximal humerus was not associated with inhospital death, but it was independently associated with inpatient adverse events (odds ratio (OR) 4.4, 95% confidence interval (CI) 4.2-4.6), prolonged hospital stay (OR 2.8, 95% CI 2.7-2.9), and increased nonroutine discharge (OR 1.8, 95% CI 1.7-1.9).

CONCLUSIONS

Inpatients with fracture of the proximal humerus who receive transfusion are not more likely to die in hospital, but they do stay longer, experience more adverse events, and are less likely to be discharged home. Additional study is merited to determine if the judicious use of blood transfusion in the perioperative period can decrease inpatient morbidity and health-care resource utilisation.

LEVEL OF EVIDENCE

Level II, Retrospective Design, Prognosis Study.

The interaction between microglia and neural stem/precursor cells

In the adult mammalian brain, neurogenesis from neural stem/precursor cell occurs within two regions, the subgranular zone (SGZ) in the dentate gyrus (DG) and the subventricular zone (SVZ) lining the lateral ventricles. The function of neural stem cell is enhanced by external stimuli, such as injury and inflammation. Microglia, as the main immune modulating cells, play important roles in the central nervous system (CNS). Recently, select discoveries reported that microglia might influence the proliferation, differentiation and survival of neural precursor cells (NPCs). Other studies revealed that NPCs might reversibly regulate the function of microglia. Accordingly, in this review we focus on the interaction between microglia and NPCs.

Perioperative blood transfusion affects hepatitis C virus (HCV)-specific immune responses and outcome following liver transplantation in HCV-infected patients

OBJECTIVES

Perioperative factors can affect outcomes of liver transplantation (LT) in recipients with hepatitis C virus (HCV) infection. This study was conducted to investigate whether the immunomodulatory effects of packed red blood cells (PRBC) and platelets administered in the perioperative period might affect immune responses to HCV and thus outcomes in LT recipients.

METHODS

Data for a total of 257 HCV LT recipients were analysed. Data on clinical demographics including perioperative transfusion (during and within the first 24 h), serum cytokine concentration, HCV-specific interferon-γ (IFN-γ) and interleukin-17 (IL-17) producing cells, and outcomes including graft and patient survival were analysed.

RESULTS

Patient survival was higher in HCV LT recipients who did not receive transfusions (Group 1, n = 65) than in those who did (Group 2, n = 192). One-year patient survival was 95% in Group 1 and 88% in Group 2 (P = 0.02); 5-year survival was 77% in Group 1 and 66% in Group 2 (P = 0.05). Group 2 had an increased post-transplant viral load (P = 0.032) and increased incidence of advanced fibrosis at 1 year (P = 0.04). After LT, Group 2 showed increased IL-10, IL-17, IL-1β and IL-6, and decreased IFN-γ, and a significantly increased rate of IL-17 production against HCV antigen. Increasing donor age (P = 0.02), PRBC transfusion (P < 0.01) and platelets administration were associated with worse survival.

CONCLUSIONS

Transfusion had a negative impact on LT recipients with HCV. The associated early increase in pro-HCV IL-17 and IL-6, with decreased IFN-γ, suggests that transfusion may be associated with the modulation of HCV-specific responses, increased fibrosis and poor transplant outcomes.

Interplay between human microglia and neural stem/progenitor cells in an allogeneic co-culture model

Experimental neural cell therapies, including donor neural stem/progenitor cells (NPCs) have been reported to offer beneficial effects on the recovery after an injury and to counteract inflammatory and degenerative processes in the central nervous system (CNS). The interplay between donor neural cells and the host CNS still to a large degree remains unclear, in particular in human allogeneic conditions. Here, we focused our studies on the interaction of human NPCs and microglia utilizing a co-culture model. In co-cultures, both NPCs and microglia showed increased survival and proliferation compared with mono-cultures. In the presence of microglia, a larger subpopulation of NPCs expressed the progenitor cell marker nestin, whereas a smaller group of NPCs expressed the neural markers polysialylated neural cell adhesion molecule, A2B5 and glial fibrillary acidic protein compared with NPC mono-cultures. Microglia thus hindered differentiation of NPCs. The presence of human NPCs increased microglial phagocytosis of latex beads. Furthermore, we observed that the expression of CD200 molecules on NPCs and the CD200 receptor protein on microglia was enhanced in co-cultures, whereas the release of transforming growth factor-β was increased suggesting anti-inflammatory features of the co-cultures. To conclude, the interplay between human allogeneic NPCs and microglia, significantly affected their respective proliferation and phenotype. Neural cell therapy including human donor NPCs may in addition to offering cell replacement, modulate host microglial phenotypes and functions to benefit neuroprotection and repair.

Immunologic profiles of red blood cells using in vitro models of transfusion

BACKGROUND

Transfusion of packed red blood cells (RBCs) produces a myriad of immunologic derangements, from suppressive to stimulatory. Proliferation of human T cells is suppressed in vitro after exposure to processed red blood cells (PRBCs). We hypothesized that this effect would be mitigated by using fresh RBCs. We also hypothesized that this suppressive effect was a generalized effect on lymphocyte proliferation and would be observed in both CD4+ and CD8+ T-cell subpopulations as well as B cells.

MATERIALS AND METHODS

We isolated human T cells from donor peripheral blood mononuclear cells and exposed them to either blood bank PRBCs or fresh RBCs from volunteer donors and stimulated them with anti-CD3/anti-CD28. Human B cells were stimulated with lipopolysaccharide and exposed to PRBCs or fresh RBCs. We measured proliferation of B cells by thymidine incorporation assays. We also treated RBCs with citrate-phosphate-dextrose (CPD) at different time points before culture them with stimulated T cells to determine the role of this common RBC storage solution in lymphocyte proliferation.

RESULTS

In vitro proliferation of CD4+ and CD8+ T cells was suppressed by blood bank RBCs. This suppression is eliminated when fresh RBCs were used. The B cells showed inhibition of proliferation when exposed to similar conditions, which appeared to be consistent over serial dilutions. Fresh RBCs exposed to CPD did not appear suppressive in the first 6 h after exposure.

CONCLUSIONS

T-cell and B-cell proliferation inhibition by blood banked RBCs suggests a generalized effect of RBCs on cellular proliferation. The lack of suppression by fresh RBCs further suggests that something involved in blood banking alters RBC properties such that they attain a suppressive phenotype. One such blood banking component, CPD, does not appear to affect this suppressive phenotype within the first 6 h.

1α,25-dihydroxyvitamin D3 promotes CD200 expression by human peripheral and airway-resident T cells

BACKGROUND

CD200, a cell-surface immunoglobulin-like molecule expressed by immune and stromal cells, dampens the pro-inflammatory activity of tissue-resident innate cells via its receptor, CD200R. This interaction appears critical for peripheral immune tolerance, particularly in the airways where excessive inflammation is undesirable. Vitamin D contributes to pulmonary health and promotes regulatory immune pathways, therefore its influence on CD200 and CD200R was investigated.

METHODS

CD200 and CD200R expression were assessed by qPCR and immunoreactivity of human lymphoid, myeloid and epithelial cells following 1α,25-dihydroxyvitamin D3 (1α,25VitD3) exposure in vitro and in peripheral T cells following 1α,25VitD3 oral ingestion in vivo. The effect of 1α25VitD3 was also assessed in human airway-resident cells.

RESULTS

1α25VitD3 potently upregulated CD200 on peripheral human CD4+ T cells in vitro, and in vivo there was a trend towards upregulation in healthy, but not asthmatic individuals. CD200R expression was not modulated in any cells studied. CD200 induction was observed to a lesser extent in CD8+ T cells and not in B cells or airway epithelium. T cells isolated from the human airway also responded strongly to 1α25VitD3 to upregulate CD200.

CONCLUSIONS

The capacity of 1α,25-dihydroxyvitamin D3 to induce CD200 expression by peripheral and respiratory tract T cells identifies an additional pathway via which vitamin D can restrain inflammation in the airways to maintain respiratory health.

Reprogramming tumor-associated dendritic cells in vivo using miRNA mimetics triggers protective immunity against ovarian cancer

Modulating the activity of miRNAs provides opportunities for novel cancer interventions. However, low bioavailability and poor cellular uptake are major challenges for delivering miRNA mimetics specifically to tumor cells. Here, we took advantage of the spontaneous enhanced endocytic activity of ovarian cancer-associated dendritic cells (DC) to selectively supplement the immunostimulatory miRNA miR-155. In vivo processing of nanoparticles carrying oligonucleotide duplexes mimicking the bulged structure of endogenous pre-miRNA (but not siRNA-like oligonucleotides) dramatically augmented miR-155 activity without saturating the RNA-induced silencing complex. Endogenous processing of synthetic miR-155 favored Ago2 and, to a lesser extent, Ago4 loading, resulting in genome-wide transcriptional changes that included silencing of multiple immunosuppressive mediators. Correspondingly, tumor-infiltrating DCs were transformed from immunosuppressive to highly immunostimulatory cells capable of triggering potent antitumor responses that abrogated the progression of established ovarian cancers. Our results show both the feasibility and therapeutic potential of supplementing/replenishing miRNAs in vivo using nonviral approaches to boost protective immunity against lethal tumors. Thus, we provide a platform, an optimized design, and a mechanistic rationale for the clinical testing of nonviral miRNA mimetics.

Blood storage duration and biochemical recurrence of cancer after radical prostatectomy

OBJECTIVE

To test the hypothesis that perioperative transfusion of allogeneic and autologous red blood cells (RBCs) stored for a prolonged period speeds biochemical recurrence of prostate cancer after prostatectomy.

PATIENTS AND METHODS

We evaluated biochemical prostate cancer recurrence in men who had undergone radical prostatectomy and perioperative blood transfusions from July 6, 1998, through December 27, 2007. Those who received allogeneic blood transfusions were assigned to nonoverlapping "younger," "middle," and "older" RBC storage duration groups. Those who received autologous RBC transfusions were analyzed using the maximum storage duration as the primary exposure. We evaluated the association between RBC storage duration and biochemical recurrence using multivariable Cox proportional hazards regression.

RESULTS

A total of 405 patients received allogeneic transfusions. At 5 years, the biochemical recurrence-free survival rate was 74%, 71%, and 76% for patients who received younger, middle, and older RBCs, respectively; our Cox model indicated no significant differences in biochemical recurrence rates between the groups (P=.82; Wald test). Among patients who received autologous transfusions (n=350), maximum RBC age was not significantly associated with biochemical cancer recurrence (P=.95). At 5 years, the biochemical recurrence-free survival rate was 85% and 81% for patients who received younger and older than 21-day-old RBCs, respectively.

CONCLUSION

In patients undergoing radical prostatectomy who require RBC transfusion, recurrence risk does not appear to be independently associated with blood storage duration.