One big unhappy family: transfusion alloimmunization, thrombosis, and immune modulation/inflammation

MicroRNA 320a and Membrane Antigens as Tools to Evaluate the Pathophysiology of Platelets Stored in Blood Banks

Our research group, through the analysis of miRNomes in platelet concentrates (PCs) stored in blood banks, identified and validated the miR-127 and miR-320a miRNAs as biomarkers of platelet storage lesions (PSLs) in PCs. In order to validate the miRNAs 127 and 320a methodologically, as PSL biomarkers in a large number of PC bags, we also evaluated important immunological markers involved in the platelet activation/aggregation process—the CD62P receptor (P-selectin), the surface glycoproteins (GP) IIb/IIIa, and the purinergic P2Y12 receptor—via flow cytometry. The miRNAs miR-127 and miR-320a were quantified by real-time quantitative PCR (RT-qPCR). To carry out this study, 500 collection tubes were used at the upper edge of the PC bags containing platelets. Each tube was divided into seven equal parts (totaling 3500 samples) for platelet analysis from 7 different storage days, where the 1st day represents the high-quality control, and the 7th day corresponds to the low-quality control of the platelets. After analyzing all parameters during storage days, it was concluded that the relative quantification of miR-320a below 0.50 and the CD62P receptor below 27.92% are reliable indicators of the absence of storage lesions in blood banks. We believe that the values found in the expression of the CD62P receptor legitimize the use of the miR-320a and miR-127 miRNAs to build a kit capable of accurately measuring whether the stored platelets are suitable for transfusion.

Evaluation of platelet activation in leukocyte-depleted platelet concentrates during storage

Structural and functional changes in platelets during storage can lead to the loss of platelet reactivity and response. Our aim was to evaluate leukocyte-depleted platelet concentrates on storage days 0, 3 and 5, obtained by in-line filtration. In non-filtered platelet concentrates (NF-PC) group, 180 whole blood units were collected with quadruple blood bags and then compared to another group of 180 whole blood units (leukocyte-depleted platelet concentrates [LD-PC]), collected in Imuflex Whole Blood Filter Saving Platelets (WB-SP) bags with an integrated leukoreduction filter, with regard to the platelet quality and characteristics. The efficacy of the two techniques for platelet concentrate preparation was evaluated by white blood cell (WBC) and platelet count on day 0. The partial pressure of oxygen (pO2), pH, platelets positive for P-selectin (CD62P), CD63, cluster of differentiation 42b (CD42b), phosphatidylserine (PS), and mitochondrial membrane potential (MMP) were analyzed during the storage in both groups. A significantly lower WBC count and higher platelet count was observed in LD-PC compared to NF-PC group, indicating the overall efficacy of the first technique. During the 5-day storage, pH and pO2 decreased in both groups. In LD-PC group, higher pH, increased pO2 and decreased platelet surface expression of CD62P, CD63 and PS were observed compared to NF-PC group. In both groups, the percentage of CD42b positive platelets and MMP did not change significantly during the 5-day period. The assessment of different markers of platelet activation may be an effective tool in evaluating the quality of platelets during storage. A better understanding of platelet activation may provide new insights for developing a novel therapeutic approach in the manipulation of platelet aggregation.

Genomewide association study of HLA alloimmunization in previously pregnant blood donors

BACKGROUND

Alloimmunization through blood transfusion, transplantation, or circulating fetal cells during pregnancy is a significant concern. Some exposed individuals make alloantibodies while others do not, implying variation in genetic risk factors.

STUDY DESIGN AND METHODS

We conducted a genomewide association study (GWAS) of 9,427,497 single-nucleotide polymorphisms (SNPs) to identify genetic variants for HLA alloimmunization in previously pregnant blood donors with (n = 752) and without (n = 753) HLA Class I or II alloantibodies.

RESULTS

A SNP in the neurexophilin 2 (NXPH2) gene surpassed genome-wide significance (p = 2.06 × 10-8 ), with multiple adjacent markers p < 10-6 , for women with anti-Class I alloantibodies only. Little is currently known about the function of NXPH2, although gene family members have been shown to impact immunity. SNPs in the E2F7 gene, a transcription factor related to cell cycle control and cellular proliferation, also approached genomewide significance (p = 2.5 × 10-7 ).

CONCLUSION

Further work to extend the GWAS approach and to characterize variants in NXPH2 and E2F7 in the context of alloantibody formation is warranted.

Perioperative blood transfusion and the clinical outcomes of patients undergoing cholangiocarcinoma surgery: a systematic review and meta-analysis

Several studies have reported different results on the association between perioperative blood transfusion (PBT) and clinical outcomes for patients undergoing cholangiocarcinoma surgery. So far, no systematic review and meta-analysis have focused on this inconsistent issue. Therefore, we carried out a systematic review and meta-analysis to evaluate the association between PBT and the clinical outcomes of cholangiocarcinoma surgery patients. EMBASE, PubMed, Web of Science, and the Cochrane Library were searched from their inception to 6 April 2016 to evaluate the relationship between PBT and clinical outcomes for patients undergoing cholangiocarcinoma surgery. The pooled hazard ratio (HR) with a 95% confidence interval (CI) was calculated using the Cochrane Collaboration's RevMan 5.3 software. A total of 10 studies (1719 patients) were included in the meta-analysis. Pooled analysis showed that PBT was associated with worse 5-year survival rate (HR=1.67, 95% CI=1.41-1.98, P<0.0001) and median overall survival (OS) (HR=1.45, 95% CI=1.14-1.83, P=0.002) in the patients who underwent cholangiocarcinoma surgery. Subgroup analysis showed that intraoperative blood transfusion was also associated with worse 5-year survival rate (HR=1.95, 95% CI=1.49-2.57, P<0.00001). Intraoperative blood transfusion is associated with poor OS for patients undergoing cholangiocarcinoma surgery because it will increase the risk of death. Postoperative blood transfusion may not be associated with OS. In addition, the relationship between PBT and the postoperative complication rate of cholangiocarcinoma surgery is still unclear.

Morbidity and Mortality after High-dose Transfusion

Background

It is well recognized that increased transfusion volumes are associated with increased morbidity and mortality, but dose–response relations between high- and very-high-dose transfusion and clinical outcomes have not been described previously. In this study, the authors assessed (1) the dose–response relation over a wide range of transfusion volumes for morbidity and mortality and (2) other clinical predictors of adverse outcomes.

Methods

The authors retrospectively analyzed electronic medical records for 272,592 medical and surgical patients (excluding those with hematologic malignancies), 3,523 of whom received transfusion (10 or greater erythrocyte units throughout the hospital stay), to create dose–response curves for transfusion volumes and in-hospital morbidity and mortality. Prehospital comorbidities were assessed in a risk-adjusted manner to identify the correlation with clinical outcomes.

Results

For patients receiving high- or very-high-dose transfusion, infections and thrombotic events were four to five times more prevalent than renal, respiratory, and ischemic events. Mortality increased linearly over the entire dose range, with a 10% increase for each 10 units of erythrocytes transfused and 50% mortality after 50 erythrocyte units. Independent predictors of mortality were transfusion dose (odds ratio [OR], 1.037; 95% CI, 1.029 to 1.044), the Charlson comorbidity index (OR, 1.209; 95% CI, 1.141 to 1.276), and a history of congestive heart failure (OR, 1.482; 95% CI, 1.062 to 2.063).

Conclusions

Patients receiving high- or very-high-dose transfusion are at especially high risk for hospital-acquired infections and thrombotic events. Mortality increased linearly over the entire dose range and exceeded 50% after 50 erythrocyte units.

Resveratrol preserves the function of human platelets stored for transfusion

Stored platelets undergo biochemical, structural and functional changes that lead to decreased efficacy and safety of platelet transfusions. Not only do platelets acquire markers of activation during storage, but they also fail to respond normally to agonists post-storage. We hypothesized that resveratrol, a cardioprotective antioxidant, could act as a novel platelet storage additive to safely prevent unwanted platelet activation during storage, while simultaneously preserving normal haemostatic function. Human platelets treated with resveratrol and stored for 5 d released less thromboxane B2 and prostaglandin E2 compared to control platelets. Resveratrol preserved the ability of platelets to aggregate, spread and respond to thrombin, suggesting an improved ability to activate post-storage. Utilizing an in vitro model of transfusion and thromboelastography, clot strength was improved with resveratrol treatment compared to conventionally stored platelets. The mechanism of resveratrol's beneficial actions on stored platelets was partly mediated through decreased platelet apoptosis in storage, resulting in a longer half-life following transfusion. Lastly, an in vivo mouse model of transfusion demonstrated that stored platelets are prothrombotic and that resveratrol delayed vessel occlusion time to a level similar to transfusion with fresh platelets. We show resveratrol has a dual ability to reduce unwanted platelet activation during storage, while preserving critical haemostatic function.

Platelet transfusion - the new immunology of an old therapy

Platelet transfusion has been a vital therapeutic approach in patients with hematologic malignancies for close to half a century. Randomized trials show that prophylactic platelet transfusions mitigate bleeding in patients with acute myeloid leukemia. However, even with prophylactic transfusions, as many as 75% of patients, experience hemorrhage. While platelet transfusion efficacy is modest, questions and concerns have arisen about the risks of platelet transfusion therapy. The acknowledged serious risks of platelet transfusion include viral transmission, bacterial sepsis, and acute lung injury. Less serious adverse effects include allergic and non-hemolytic febrile reactions. Rare hemolytic reactions have occurred due to a common policy of transfusing without regard to ABO type. In the last decade or so, new concerns have arisen; platelet-derived lipids are implicated in transfusion-related acute lung injury after transfusion. With the recognition that platelets are immune cells came the discoveries that supernatant IL-6, IL-27 sCD40L, and OX40L are closely linked to febrile reactions and sCD40L with acute lung injury. Platelet transfusions are pro-inflammatory, and may be pro-thrombotic. Anti-A and anti-B can bind to incompatible recipient or donor platelets and soluble antigens, impair hemostasis and thus increase bleeding. Finally, stored platelet supernatants contain biological mediators such as VEGF and TGF-β1 that may compromise the host versus tumor response. This is particularly of concern in patients receiving many platelet transfusions, as for acute leukemia. New evidence suggests that removing stored supernatant will improve clinical outcomes. This new view of platelets as pro-inflammatory and immunomodulatory agents suggests that innovative approaches to improving platelet storage and pre-transfusion manipulations to reduce toxicity could substantially improve the efficacy and safety of this long-employed therapy.