Transfusion-associated circulatory overload and transfusion-related acute lung injury

HMGB1/TLR4 Signaling Affects Regulatory T Cells in Acute Lung Injury

Background

High-mobility group box-1 protein (HMGB1) serves as the prototypic damage-associated molecular pattern molecule, and TLR4 is considered a receptor for HMGB1. Regulatory T cells (Tregs) play a crucial role in infectious diseases. The role of HMGB1 in the modulation of Tregs is of great interest.

Methods

Serum HMGB1 and Treg proportions were detected in 58 patients with acute lung injury (ALI) and 36 healthy volunteers. The correlations of these parameters with disease severity were analyzed. The WT and TLR4^-/- mice were administered HMGB1 by intratracheal injection. After 48 h, the mice were sacrificed. The morphological changes and wet/dry ratio of the lung were measured. Spleen CD4⁺CD25⁺ Tregs were sorted from spleen cells, the expression of FOXP3 and CTLA-4, and releasing of cytokines was detected. CD4⁺CD25⁺ Tregs were cocultured with effector T cells, the inhibitory effect, and release of cytokines was detected.

Results

Significantly increased plasma levels of HMGB1 and reduced CD4⁺CD25⁺CD127^low Tregs were detected in ALI patients. In the mouse model, lung injury was significantly increased after HMGB1 instillation in the WT and TLR4^-/- groups compared with control group. The lung wet/dry ratio and the TNF-α and IL-1β contents in BALF were significantly increased, and the severity of WT mice was higher than that of TLR4^-/- mice. The expression of FOXP3 and CTLA-4 in TLR4^-/- mice was significantly increased compared with that in WT mice and was associated with a similar trend of IL-10 and TGF-β levels (p<0.05). In coculture with effector T cells, Tregs isolated from TLR4^-/- mice exhibited decreased IL-2 and IFN-γ and increased IL-4 levels compared with Tregs from WT mice. Increased polarization of TLR4^-/- CD4⁺CD25⁺ Treg cells to Th2 cells was observed.

Conclusion

In HMGB1-induced lung injury, HMGB1 affects the expression of FOXP3 and CTLA-4 through TLR4, thus reducing the immunosuppressive function of Treg cells.

The Immune System in Transfusion-Related Acute Lung Injury Prevention and Therapy: Update and Perspective

As an initiator of respiratory distress, transfusion-related acute lung injury (TRALI) is regarded as one of the rare complications associated with transfusion medicine. However, to date, the pathogenesis of TRALI is still unclear, and specific therapies are unavailable. Understanding the mechanisms of TRALI may promote the design of preventive and therapeutic strategies. The immune system plays vital roles in reproduction, development and homeostasis. Sterile tissue damage, such as physical trauma, ischemia, or reperfusion injury, induces an inflammatory reaction that results in wound healing and regenerative mechanisms. In other words, in addition to protecting against pathogens, the immune response may be strongly associated with TRALI prevention and treatment through a variety of immunomodulatory strategies to inhibit excessive immune system activation. Immunotherapy based on immune cells or immunological targets may eradicate complications. For example, IL-10 therapy is a promising therapeutic strategy to explore further. This review will focus on ultramodern advances in our understanding of the potential role of the immune system in TRALI prevention and treatment.

Identifying and Understanding Transfusion Reactions in the Oncology Population

OBJECTIVES

To provide an overview of transfusion reactions, their underlying pathophysiology, clinical presentation, and recommendations for nursing management.

DATA SOURCES

We researched peer-reviewed journal articles, book chapters, Internet, and lecture proceedings.

CONCLUSION

Transfusion reactions are adverse reactions to blood products frequently seen in the oncology population and can significantly vary in severity and etiology. Oncology nurses are in a critical position to assist with prevention, early detection, and time-sensitive treatment of transfusion reactions.

IMPLICATIONS FOR NURSING PRACTICE

The oncology nurse's comprehensive understanding of possible transfusion reactions and management recommendations is key for optimal care of the oncology patient.

Bedside Allogeneic Erythrocyte Washing with a Cell Saver to Remove Cytokines, Chemokines, and Cell-derived Microvesicles

BACKGROUND

Removal of cytokines, chemokines, and microvesicles from the supernatant of allogeneic erythrocytes may help mitigate adverse transfusion reactions. Blood bank-based washing procedures present logistical difficulties; therefore, we tested the hypothesis that on-demand bedside washing of allogeneic erythrocyte units is capable of removing soluble factors and is feasible in a clinical setting.

METHODS

There were in vitro and prospective, observation cohort components to this a priori planned substudy evaluating bedside allogeneic erythrocyte washing, with a cell saver, during cardiac surgery. Laboratory data were collected from the first 75 washed units given to a subset of patients nested in the intervention arm of a parent clinical trial. Paired pre- and postwash samples from the blood unit bags were centrifuged. The supernatant was aspirated and frozen at -70°C, then batch-tested for cell-derived microvesicles, soluble CD40 ligand, chemokine ligand 5, and neutral lipids (all previously associated with transfusion reactions) and cell-free hemoglobin (possibly increased by washing). From the entire cohort randomized to the intervention arm of the trial, bedside washing was defined as feasible if at least 75% of prescribed units were washed per protocol.

RESULTS

Paired data were available for 74 units. Washing reduced soluble CD40 ligand (median [interquartile range]; from 143 [1 to 338] ng/ml to zero), chemokine ligand 5 (from 1,314 [715 to 2,551] to 305 [179 to 488] ng/ml), and microvesicle numbers (from 6.90 [4.10 to 20.0] to 0.83 [0.33 to 2.80] × 106), while cell-free hemoglobin concentration increased from 72.6 (53.6 to 171.6) mg/dl to 210.5 (126.6 to 479.6) mg/dl (P < 0.0001 for each). There was no effect on neutral lipids. Bedside washing was determined as feasible for 80 of 81 patients (99%); overall, 293 of 314 (93%) units were washed per protocol.

CONCLUSIONS

Bedside erythrocyte washing was clinically feasible and greatly reduced concentrations of soluble factors thought to be associated with transfusion-related adverse reactions, increasing concentrations of cell-free hemoglobin while maintaining acceptable (less than 0.8%) hemolysis.

EDITOR’S PERSPECTIVE

Elevated P-Selectin in Severe Covid-19: Considerations for Therapeutic Options

Background

Coronavirus disease 2019 (COVID-19) is mainly a respiratory tract disease and acute respiratory failure with diffuse microvascular pulmonary thrombosis are critical aspects of the morbidity and mortality of this new syndrome.

Purpose

The aim of our study was to investigate, in severe COVID-19 hospitalized patients, the P-selectin plasma concentration as a biomarker of endothelial dysfunction and platelet activation.

Methods

46 patients with severe or critical SARS-CoV-2 infection were included in the study. Age-matched patients then were divided in those requiring admission to the intensive care unit (ICU, ICU cases) vs those not requiring ICU hospitalization (non-ICU cases). Blood samples of severe COVID-19 patients were collected at the time of hospital admission. The quantification of soluble P-selectin was performed by ELI, assay.

Results

Our study showed a higher P-selectin plasma concentration in patients with Covid-19, regardless of ICU admission, compared to the normal reference values and compared to ten contextually sampled healthy donors (HD); (COVID-19): median 65.2 (IQRs: 45.1–81.1) vs. HD: 40.3 (IQRs: 24.3–48.7), p=0023. Moreover, results showed a significant reduction of P-sele din after platelets removal in HD, in contrast, both ICU and non-ICU COVID-19 patients showed similar high levels of P-selectin with and without platelets.

Conclusion

Elevation of P-selectin suggests a central role of platelet endothelium interaction as part of the multifaced pathogenic mechanism of COVID-19 leading to the local activation of hemostatic system forming pulmonary thrombi. Further work is necessary to determine the therapeutic role of antiplatelets agents or of the anti P-selectin antibody Crizanlizumab.

Inhibition of Dendritic Cell Activation and Modulation of T Cell Polarization by the Platelet Secretome

Platelet transfusions are a frequently administered therapy for especially hemato-oncological patients with thrombocytopenia. Next to their primary function in hemostasis, currently there is increased attention for the capacity of platelets to affect the function of various cells of the immune system. Here, we investigate the capacity of platelets to immuno-modulate monocyte-derived dendritic cells (moDC) as well as primary dendritic cells and effects on subsequent T cell responses. Platelets significantly inhibited pro-inflammatory (IL-12, IL-6, TNFα) and increased anti-inflammatory (IL-10) cytokine production of moDCs primed with toll-like receptor (TLR)-dependent and TLR-independent stimuli. Transwell assays and ultracentrifugation revealed that a soluble factor secreted by platelets, but not microvesicles, inhibited DC activation. Interestingly, platelet-derived soluble mediators also inhibited cytokine production by human ex vivo stimulated myeloid CD1c+ conventional DC2. Moreover, platelets and platelet-derived soluble mediators inhibited T cell priming and T helper differentiation toward an IFNγ+ Th1 phenotype by moDCs. Overall, these results show that platelets are able to inhibit the pro-inflammatory properties of DCs, and may even induce an anti-inflammatory DC phenotype, with decreased T cell priming capacity by the DC. The results of this study provide more insight in the potential role of platelets in immune modulation, especially in the context of platelet transfusions.

Transfusion-associated circulatory overload and high blood pressure: A multicentre retrospective study in Japan

BACKGROUND

Transfusion-associated circulatory overload (TACO) is an adverse reaction associated with a high risk of mortality. The actual incidence of TACO and hypertension associated with transfusion in Japan is unknown.

METHODS

A multicentre retrospective observational study was conducted across 23 institutions during the 1-year period of 2016. Patients were included if they developed TACO or their blood pressure (either systolic or diastolic) increased by at least 30 mmHg during the transfusion. TACO was confirmed by the primary physicians and transfusion medicine teams and recorded in the data on passive surveillance, and additional data were extracted from electronic medical records.

RESULTS

In our patient cohort of 31 384 patients who underwent transfusion, the incidence of TACO and hypertension was 0·03% and 0·2%, respectively. However, 43% of the participating institutions didn't report any cases. When comparing risk factors between the TACO and hypertension groups, there were significant differences in comorbidities, such as abnormal findings on chest x-ray. Significant differences between the two groups were observed post-transfusion pulse rate, body temperature and oxygen saturation (P < 0·01). In the group of patients with hypertension, the level of BNP increased significantly after transfusion in 45% (5/11) of the patients. We identified 4 patients in the hypertension group who met the new ISBT's TACO criteria.

CONCLUSION

Our study suggests that more attention should be given to TACO in Japan, particularly in terms of improving surveillance systems. For the early diagnosis of TACO, it is crucial to carefully monitor vital signs including blood pressure.

Transfusion Reactions in Pediatric Patients: An Analysis of 5 Years of Hemovigilance Data From a National Center for Children's Health in China

Objective: This study aimed to describe transfusion reactions of pediatric patients from a National Center for Children's Health in China and to examine reaction incidents, reaction types by blood transfusion, and the associated blood products resulting in transfusion reactions. Methods: We compared transfusion reaction rates, among platelets, plasma, and red blood cells (RBCs) using a retrospective analysis of pediatric patients treated with blood transfusion based on data from the National Center for Children's Health (Beijing, China) by a hemovigilance reporting system from January 2015 to December 2019. Results: Over the past 5 years, 165 reactions were reported, and the overall incidence was 1.35‰ (95% CI: 1.14-1.55‰; 165/122,652); for each separate year, the incidences were 1.25‰ (95% CI: 0.76-1.74‰; 25/20,035; 2015), 1.09‰ (95% CI: 0.65-1.52‰; 24/22,084; 2016), 1.66‰ (95% CI: 1.14-2.18‰; 39/23,483; 2017), 1.36‰ (95% CI: 0.92-1.81‰; 36/26,440; 2018) and 1.34‰ (95% CI: 0.93-1.75‰; 41/30,610; 2019). Transfusion reaction incidents by person included 0.37‰ (95% CI: 0.21-0.53‰; 21/56,815) RBCs, 2.98‰ (95% CI: 2.33-3.64‰; 79/26,496) platelets and 1.65‰ (95% CI: 1.25-2.05‰; 65/39,341) frozen plasma. According to the analysis by blood products, the incidence of transfusion was 0.34‰ (95% CI: 0.20-0.48‰; 23/66,958) for RBCs, 3.21‰ (95% CI: 2.50-3.92‰; 78/24,318.5) for platelets, and 0.94‰ (95% CI: 0.71-1.17‰; 64/67,912) for frozen plasma. Transfusion reactions were most commonly associated with platelets, followed by plasma and RBC transfusions. The types of blood transfusion reactions were mainly allergic reactions (86.67%) and febrile non-hemolytic transfusion reactions (FNHTRs, 4.24%). The disease types of pediatric patients with transfusion reactions were concentrated among those with blood system diseases. A total of 80.61% of children with transfusion reactions had a previous blood transfusion history. Conclusions: Transfusion reactions are still relatively common in pediatric patients, and additional studies are necessary to address the differences in reaction rates, especially allergic and FNHTRs. Robust hemovigilance systems do include a special section dedicated to children will further the understanding of these reactions and trends, and prospective randomized clinical controlled trials may need to be conducted to perform preventive and corrective measures.

Pediatric Hemovigilance and Adverse Transfusion Reactions

Some types of transfusion reactions occur more frequently in the pediatric than the adult population. Allergic reactions are the most common, followed by nonhemolytic transfusion reactions; male children seem most susceptible to such reactions. Platelets are often implicated and pulmonary reactions are understudied in children. Clinical sequelae in neonates, such as bronchopulmonary dysplasia/chronic lung disease and intraventricular hemorrhage, have received increasing attention in relation to transfusion. There is a need to better understand the pathophysiology of transfusion reactions in neonatal and pediatric populations so preventive strategies can be undertaken. There is also a need for robust hemovigilance systems.

Transfusion in the mechanically ventilated patient

Red blood cell transfusions are a frequent intervention in critically ill patients, including in those who are receiving mechanical ventilation. Both these interventions can impact negatively on lung function with risks of transfusion-related acute lung injury (TRALI) and other forms of acute respiratory distress syndrome (ARDS). The interactions between transfusion, mechanical ventilation, TRALI and ARDS are complex and other patient-related (e.g., presence of sepsis or shock, disease severity, and hypervolemia) or blood product-related (e.g., presence of antibodies or biologically active mediators) factors also play a role. We propose several strategies targeted at these factors that may help limit the risks of associated lung injury in critically ill patients being considered for transfusion.

Mortality reduction in 46 severe Covid-19 patients treated with hyperimmune plasma. A proof of concept single arm multicenter trial

Hyperimmune plasma from Covid-19 convalescent is a potential treatment for severe Covid-19. We conducted a multicenter one arm proof of concept interventional study. Patients with Covid-19 disease with moderate-to-severe Acute Respiratory Distress Syndrome, elevated C-reactive Protein and need for mechanical ventilation and/or CPAP were enrolled. One to three 250-300 ml unit of hyperimmune plasma (neutralizing antibodies titer ≥1:160) were administered. Primary outcome was 7-days hospital mortality. Secondary outcomes were PaO2/FiO2, laboratory and radiologic changes, as well as weaning from mechanical ventilation and safety. The study observed 46 patients from March, 25 to April, 21 2020. Patients were aged 63, 61% male, of them, 30 were on CPAP and 7 intubated. PaO2/FiO2 was 128 (SD 47). Bilateral infiltrates on chest X-ray was present in 36 patients (84%). Symptoms and ARDS duration were 14 (SD 7) and 6 days (SD 3). Three patients (6.5%) died within 7 days as compared to an expected 15% from the National Statistics and 30% from a small concurrent cohort of 23 patients. The upper one-sided 90%CI was 13.9%, allowing to reject the null hypothesis of a 15% mortality. PaO2/FiO2 increased by 112 units (95%CI 82 to142) in survivors, the chest radiogram severity decreased in 23% (95%CI 5% to 42%); CRP, Ferritin and LDH decreased by 60, 36 and 20% respectively. Weaning from CPAP was obtained in 26/30 patients and 3/7 were extubated. Five serious adverse events occurred in 4 patients (2 likely, 2 possible treatment related). In conclusion, Hyperimmune plasma in Covid-19 shows promising benefits, to be confirmed in a randomized controlled trial. This proof of concept study could open to future developments including hyperimmune plasma banking, development of standardized pharmaceutical products and monoclonal antibodies.

Complement activation on endothelium initiates antibody-mediated acute lung injury

Antibodies targeting human leukocyte antigen (HLA)/major histocompatibility complex (MHC) proteins limit successful transplantation and transfusion, and their presence in blood products can cause lethal transfusion-related acute lung injury (TRALI). It is unclear which cell types are bound by these anti-leukocyte antibodies to initiate an immunologic cascade resulting in lung injury. We therefore conditionally removed MHC class I (MHC I) from likely cellular targets in antibody-mediated lung injury. Only the removal of endothelial MHC I reduced lung injury and mortality, related mechanistically to absent endothelial complement fixation and lung platelet retention. Restoration of endothelial MHC I rendered MHC I-deficient mice susceptible to lung injury. Neutrophil responses, including neutrophil extracellular trap (NET) release, were intact in endothelial MHC I-deficient mice, whereas complement depletion reduced both lung injury and NETs. Human pulmonary endothelial cells showed high HLA class I expression, and posttransfusion complement activation was increased in clinical TRALI. These results indicate that the critical source of antigen for anti-leukocyte antibodies is in fact the endothelium, which reframes our understanding of TRALI as a rapid-onset vasculitis. Inhibition of complement activation may have multiple beneficial effects of reducing endothelial injury, platelet retention, and NET release in conditions where antibodies trigger these pathogenic responses.

Transfusion-associated circulatory overload in gastroenterology

BACKGROUND

Transfusion-associated circulatory overload (TACO) is a rare life-threatening event associated with transfusion. This study aimed to identify any case of TACO in a large cohort of highly transfused patients with gastrointestinal tract (GI) bleeding.

MATERIALS AND METHODS

Data from patients who underwent an oesophago-gastro-duodenoscopy (OGD) were collected over one year from the gastroenterology service of a regional hospital.

RESULTS

A total of 278 patients were identified, of which 81 required transfusion. In total, 811 blood components were transfused (red cell concentrate, platelets, plasma), leading to a cumulative TACO incidence of 12.3%. The probability of developing TACO was greater for patients aged ≥80 years (OR=3.9%; p=0.0058), with renal disease (OR=1.9%, p=not significant) and with cardiac disease (OR 11.1%; p=0.003). Patients with TACO had a lower overall survival (52 vs 20% at 3 years, p=0.034, HR=2.19, 95% CI: 1.04-4.63) compared to patients with cirrhosis without TACO (57 vs 28% at 3 years, p=0.003, HR=2.20, 95% CI: 1.30-3.72). Patients with an advanced stage of liver cirrhosis (Child Pugh c10 or more) were most likely to develop TACO.

DISCUSSION

This study shows that within the GI setting TACO may be markedly under-reported. Clinical awareness for potential TACO development in GI patients with cardiac or renal disease or age >80 years is now required.

Two Episodes of Transfusion-related Acute Lung Injury (TRALI) Occurring within a Short Period

Transfusion-related acute lung injury (TRALI) is a non-hemolytic adverse reaction that occurs ≤6 hours after receiving a transfusion. A 72-year-old man with leukemia developed severe hypoxemia after platelet transfusions on two occasions within a 4-day period. During the first episode, the transfused platelet preparation was positive for anti-human-leukocyte antigen antibodies. The pathogenesis of TRALI includes an antibody-mediated mechanism and a non-antibody-mediated mechanism, in which various factors combine to activate pulmonary neutrophils. In our case, it is considered that the patient's neutrophils reached the activation threshold for the development of TRALI after the accumulation of various factors besides anti-leukocyte antibodies.

Optimal Dosage and Administration Practices for Vitamin K Antagonist Reversal With 4-Factor Prothrombin Complex Concentrate

Expert consensus and international guidelines recommend urgent co-administration of vitamin K and 4-factor prothrombin complex concentrates (4F-PCCs) to rapidly reverse VKA-related bleeding. This narrative review examined real-world evidence and strategies to optimize international normalized ratio (INR) reversal, hemostasis, and outcomes in patients receiving 4F-PCC in this setting. Key determinants for success include the appropriate use of alternative dosing and administration strategies, such as fixed dosing and increased infusion speed, adherence to institutional guidelines, and removing significant institutional barriers to reduce time to treatment. In the opinion of authors, minimizing the time to treatment with 4F-PCCs is of paramount importance when treating patients with VKA-related bleeding. Practices that safely and feasibly shorten the time to administration should be included in guidelines for institutions responsible for anticoagulant care, and adhered to in centers that perform invasive procedures on patients receiving VKA therapy. Further studies are required to optimize use of 4F-PCC, particularly in relation to the ideal dosing strategy and the role of INR.

Effect of High-Dose Erythropoietin on Blood Transfusions in Extremely Low Gestational Age Neonates: Post Hoc Analysis of a Randomized Clinical Trial

IMPORTANCE

Extremely preterm infants are among the populations receiving the highest levels of transfusions. Erythropoietin has not been recommended for premature infants because most studies have not demonstrated a decrease in donor exposure.

OBJECTIVES

To determine whether high-dose erythropoietin given within 24 hours of birth through postmenstrual age of 32 completed weeks will decrease the need for blood transfusions.

DESIGN, SETTING, AND PARTICIPANTS

The Preterm Erythropoietin Neuroprotection Trial (PENUT) is a randomized, double-masked clinical trial with participants enrolled at 19 sites consisting of 30 neonatal intensive care units across the United States. Participants were born at a gestational age of 24 weeks (0-6 days) to 27 weeks (6-7 days). Exclusion criteria included conditions known to affect neurodevelopmental outcomes. Of 3266 patients screened, 2325 were excluded, and 941 were enrolled and randomized to erythropoietin (n = 477) or placebo (n = 464). Data were collected from December 12, 2013, to February 25, 2019, and analyzed from March 1 to June 15, 2019.

INTERVENTIONS

In this post hoc analysis, erythropoietin, 1000 U/kg, or placebo was given every 48 hours for 6 doses, followed by 400 U/kg or sham injections 3 times a week through postmenstrual age of 32 weeks.

MAIN OUTCOMES AND MEASURES

Need for transfusion, transfusion numbers and volume, number of donor exposures, and lowest daily hematocrit level are presented herein.

RESULTS

A total of 936 patients (488 male [52.1%]) were included in the analysis, with a mean (SD) gestational age of 25.6 (1.2) weeks and mean (SD) birth weight of 799 (189) g. Erythropoietin treatment (vs placebo) decreased the number of transfusions (unadjusted mean [SD], 3.5 [4.0] vs 5.2 [4.4]), with a relative rate (RR) of 0.66 (95% CI, 0.59-0.75); the cumulative transfused volume (mean [SD], 47.6 [60.4] vs 76.3 [68.2] mL), with a mean difference of -25.7 (95% CI, 18.1-33.3) mL; and donor exposure (mean [SD], 1.6 [1.7] vs 2.4 [2.0]), with an RR of 0.67 (95% CI, 0.58-0.77). Despite fewer transfusions, erythropoietin-treated infants tended to have higher hematocrit levels than placebo-treated infants, most noticeable at gestational week 33 in infants with a gestational age of 27 weeks (mean [SD] hematocrit level in erythropoietin-treated vs placebo-treated cohorts, 36.9% [5.5%] vs 30.4% [4.6%] (P < .001). Of 936 infants, 160 (17.1%) remained transfusion free at the end of 12 postnatal weeks, including 43 in the placebo group and 117 in the erythropoietin group (P < .001).

CONCLUSIONS AND RELEVANCE

These findings suggest that high-dose erythropoietin as used in the PENUT protocol was effective in reducing transfusion needs in this population of extremely preterm infants.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01378273.

Evaluation of Platelet Responses in Transfusion-Related Acute Lung Injury (TRALI)

Platelets are versatile cells which are capable of eliciting nonhemostatic immune functions, especially under inflammatory conditions. Depending on the specific setting, platelets may be either protective or pathogenic in acute lung injury and acute respiratory distress syndrome (ARDS). Their role in transfusion-related acute lung injury (TRALI) is less well defined; however, it has been hypothesized that recipient platelets and transfused platelets both play a pathogenic role in TRALI. Overall, despite conflicting findings, it appears that recipient platelets may play a pathogenic role in antibody-mediated TRALI; however, their contribution appears to be limited. It is imperative to first validate the involvement of recipient platelets by standardizing the animal models, methods, reagents, and readouts for lung injury and taking the animal housing environment into consideration. For the involvement of transfused platelets in TRALI, it appears that predominantly lipids such as ceramide in stored platelets are able to induce TRALI in animal models. These studies will also need to be validated, and moreover, the platelet-derived lipid-mediated mechanisms leading to TRALI will need to be investigated.

Leukocyte-Reactive Antibodies in Female Blood Donors: The Austrian Experience

Introduction

Antibody-mediated transfusion-related acute lung injury (TRALI) is caused by antibodies against human leukocyte antigens (HLAs) or human neutrophil antigens (HNAs), and is one of the most serious complications associated with transfusion medicine. Prevention strategies like testing allo-exposed female blood donors have not yet been introduced nationwide in Austria. To assess the need and feasibility of routine leukocyte antibody testing, the prevalence of leukocyte-reactive antibodies in an Austrian female donor population was been determined using classical cell-based methods which were compared with a high-throughput bead-based method.

Methods

Sera from 1,022 female blood donors were screened using a granulocyte aggregation test (GAT) and a white blood cell immunofluorescence test (WIFT) after retesting and specification of positive samples by granulocyte immunofluorescence test (GIFT) and monoclonal antibody-specific immobilization of granulocyte antigens (MAIGA). Potential HLA reactivities were confirmed using the microbeads assay LabScreen^TM Mixed. The results in 142 donor sera and 38 well-defined reference sera were investigated by the microbeads assay LabScreen^TM Multi and compared with classical cell-based methods.

Results

Reactivity with either granulocytes and/or lymphocytes was detected in 79 sera (7.7%), with the majority being HLA-specific. Antibodies against HNA were obtained in 7 samples (0.7%). The aggregating potential of the detected antibodies was observed in 9 cases (0.9%). Most of the leukocyte-reactive antibodies occurred at a donor age of between 35 and 59 years (n = 61). LabScreen Multi showed good agreement (κ = 0.767) for HNA antibody detection by cell-based assays, but double/multiple specificities (100% of 7 anti-HNA-1b sera) as well as false-negative results (40% of 15 HNA-3-specific sera) occurred.

Discussion

Leukocyte-reactive antibody screening is advised in Austrian female donors for safe blood transfusion, including single-donor convalescent plasma treatment of COVID-19 that may be implemented soon. For the introduction of LabScreen Multi, the combination with GAT should be considered to ensure correct anti-HNA-3a detection.

Diffuse Alveolar Hemorrhage After Pediatric Hematopoietic Stem Cell Transplantation

Pulmonary complications are common following hematopoietic cell transplantation (HCT) and contribute significantly to its morbidity and mortality. Diffuse alveolar hemorrhage is a devastating non-infectious complication that occurs in up to 5% of patients post-HCT. Historically, it carries a high mortality burden of 60–100%. The etiology remains ill-defined but is thought to be due to lung injury from conditioning regimens, total body irradiation, occult infections, and other comorbidities such as graft vs. host disease, thrombotic microangiopathy, and subsequent cytokine release and inflammation. Clinically, patients present with hypoxemia, dyspnea, and diffuse opacities consistent with an alveolar disease process on chest radiography. Diagnosis is most commonly confirmed with bronchoscopy findings of progressively bloodier bronchoalveolar lavage or the presence of hemosiderin-laden macrophages on microscopy. Treatment with glucocorticoids is common though dosing and duration of therapy remains variable. Other agents, such as aminocaproic acid, tranexamic acid, and activated recombinant factor VIIa have also been tried with mixed results. We present a review of diffuse alveolar hemorrhage with a focus on its pathogenesis and treatment options.

Impact of Blood Transfusion in Free Flap Breast Reconstruction Using Propensity Score Matching

BACKGROUND

 Microvascular thrombosis has been associated with cytokine release and inflammatory syndromes which can occur as a result of blood transfusions. This phenomenon could potentially lead to complications in breast free flap reconstruction. The aim of this study was to evaluate the impact of perioperative blood transfusion in free flap breast reconstruction using large population analysis.

METHODS

 The American College of Surgeons National Quality Improvement Program database was queried for delayed free flap breast reconstructions performed in 2016. The study population was divided based on perioperative blood transfusion within 24 hours of the start of the operation. Propensity score matching analysis was used to ensure homogeneity between the two study groups. Primary outcome was unplanned return to the operating room (OR) within 30 days. Secondary outcomes were readmission and complications.

RESULTS

 A total of 1,256 patients were identified. Out of those, 91 patients received a perioperative blood transfusion. All the patients received only one unit of PRBC within the first 24 hours. Those patients were matched with similar patients who did not receive a transfusion on a ratio of 1:3 (273 patients). Patients who received a transfusion had a significantly higher incidence of reoperation (42 vs. 10%, p < 0.001). Patients who received a transfusion were more likely to return to the OR after 48 hours from the initial operation (13 vs. 5%, p = 0.001). All returns to the OR were due to flap-related complications. Perioperative blood transfusion increased the incidence of wound dehiscence (9 vs. 2%, p = 0.041) but had no protective effect on the development of other postoperative complications.

CONCLUSION

 Perioperative blood transfusion in free flap breast reconstruction is associated with an increased probability of flap-related complications and subsequent return to the OR without decreasing the probability of developing other systemic postoperative complications.

Convalescent Plasma Therapy for Coronavirus Disease 2019

Convalescent plasma has been used for decades to prevent and treat a wide range of infectious diseases for which no specific treatment is available. The use of convalescent plasma involves transfusing plasma collected from patients who have recovered from a viral illness, in an attempt to transfer virus-neutralizing antibodies and confer passive immunity. In addition to the antiviral mechanisms of neutralizing antibodies, the immunomodulatory effects of plasma components could have benefits. Several small and large-scale studies have shown the effects of convalescent plasma for the treatment of severe coronavirus disease 2019 (COVID-19). In addition to transfusion-related side effects, unexpected side effects such as antibody-dependent enhancement (ADE) may occur during convalescent plasma therapy, but early safety studies have not found any cases of ADE among more than 5,000 participants. With historical precedents and recent clinical studies, convalescent plasma therapy should be considered as a candidate therapy for COVID-19 given the limited effectiveness of antiviral drugs and lack of a vaccine. A system to secure safe collection and use of convalescent plasma should be developed as a response to the pandemic. Further clinical trials should be conducted to determine the safety and efficacy of convalescent plasma therapy concurrently with its clinical use.

Treating murine inflammatory diseases with an anti-erythrocyte antibody

Treatment of autoimmune and inflammatory diseases typically involves immune suppression. In an opposite strategy, we show that administration of the highly inflammatory erythrocyte-specific antibody Ter119 into mice remodels the monocyte cellular landscape, leading to resolution of inflammatory disease. Ter119 with intact Fc function was unexpectedly therapeutic in the K/BxN serum transfer model of arthritis. Similarly, it rapidly reversed clinical disease progression in collagen antibody-induced arthritis (CAIA) and collagen-induced arthritis and completely corrected CAIA-induced increase in monocyte Fcγ receptor II/III expression. Ter119 dose-dependently induced plasma chemokines CCL2, CCL5, CXCL9, CXCL10, and CCL11 with corresponding alterations in monocyte percentages in the blood and liver within 24 hours. Ter119 attenuated chemokine production from the synovial fluid and prevented the accumulation of inflammatory cells and complement components in the synovium. Ter119 could also accelerate the resolution of hypothermia and pulmonary edema in an acute lung injury model. We conclude that this inflammatory anti-erythrocyte antibody simultaneously triggers a highly efficient anti-inflammatory effect with broad therapeutic potential.

Anesthesia Considerations and Infection Precautions for Trauma and Acute Care Cases During the COVID-19 Pandemic: Recommendations From a Task Force of the Chinese Society of Anesthesiology

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread worldwide. During the ongoing COVID-19 epidemic, most hospitals have postponed elective surgeries. However, some emergency surgeries, especially for trauma patients, are inevitable. For patients with suspected or confirmed COVID-19, a standard protocol addressing preoperative preparation, intraoperative management, and postoperative surveillance should be implemented to avoid nosocomial infection and ensure the safety of patients and the health care workforce. With reference to the guidelines and recommendations issued by the National Health Commission and Chinese Society of Anesthesiology, this article provides recommendations for anesthesia management of trauma and emergency surgery cases during the COVID-19 pandemic.

Lipopolysaccharide-Induced Acute Lung Injury Is Associated with Increased Ran-Binding Protein in Microtubule-Organizing Center (RanBPM) Molecule Expression and Mitochondria-Mediated Apoptosis Signaling Pathway in a Mouse Model

Background

Acute lung injury (ALI) is a severe and life-threatening disorder treated in intensive care units. This study aimed to determine molecules or associated signaling pathways that are involved in lipopolysaccharide (LPS)-induced inflammation in an ALI model.

Material/Methods

An ALI mouse model was established by administering LPS (25 mg/kg via intratracheal instillation). Thirty-two ALI mice were divided into Model-4 h, Model-8 h, Model-12 h, and Model-24 h groups, while another 8 mice without LPS treatment were assigned as the Control group. Hematoxylin-eosin (HE) staining was used to evaluate inflammation of lung tissues. Wet weight/dry weight (W/D) ratio and myeloperoxidase (MPO) activity of lung tissue in ALI mice were evaluated. Expressions of Bcl-2, Bcl-XL, Bak, Bax, cleaved caspase-3 (C-caspase-3), and Ran-binding protein in microtubule-organizing center (RanBPM) were determined using Western blot analysis.

Results

LPS administration caused obvious inflammatory cell infiltration of lung tissues in ALI mice. The W/D ratio of ALI mouse lung tissues was significantly higher in Model groups than in the Control group (p<0.05). MPO activity of ALI mice was remarkably higher in Model groups compared to the Control group (p<0.05). LPS-induced ALI model mice exhibited significantly higher levels of C-caspase 3 lung tissues compared to the Control group (p<0.05). LPS-induced ALI model mice had significantly lower Bcl-XL/Bcl-2 and remarkably higher Bak/Bax expression compared with the Control group (p<0.05). LPS-induced ALI model mice displayed obviously higher RanBPM expression than in the Control group (p<0.05).

Conclusions

Lipopolysaccharide-induced acute lung injury is associated with increased RanBPM molecule expression and with mitochondria-mediated apoptosis signaling pathway in a mouse model.

Factors that influence flow through intravascular catheters: the clinical relevance of Poiseuille's law

BACKGROUND

The physics of ideal fluid flow is well characterized. However, the effect of catheter size, tubing types, injection port adjuncts, and viscosity on flow is not well described. We used a simulated environment to determine how various permutations of common elements affect fluid flow.

STUDY DESIGN AND METHODS

We tested 16 peripheral and central venous catheters to assess flow through several standard infusion sets and a rapid infuser set; tested flow through standard and blood infusion sets with the addition of intravenous extension tubing, stopcocks, and a needleless connector; and compared the relative viscosity of commonly used blood products and colloids to that of normal saline.

RESULTS

The maximal flow rate was 200 mL/min for the standard infusion set but 800 mL/min for the rapid infusion set. Choice of infusion tubing was the rate-limiting component for many larger catheters. A 14-gauge, single-lumen central venous catheter (CVC) and 18-gauge peripheral intravenous catheter (PIV) had equivalent flow rates with all infusion sets. A 16-gauge single-lumen CVC allowed a flow rate that was slower than that of a 20-gauge PIV, and faster than that of a 22-gauge PIV. The addition of adjuncts slowed flow rate. Needleless connectors had the greatest impact, reducing flow by 75% for the blood infusion set. Packed red blood cells had a viscosity 4.5 times that of normal saline and thereby reduced flow.

CONCLUSION

Catheter and tubing choice, adjuncts, and fluid viscosity influence flow rates. Our results will help inform adequate vascular access planning in the perioperative environment.

Plasma-based COVID-19 treatments in low- and middle-income nations pose a high risk of an HIV epidemic

Convalescent plasma therapy holds promise as a transient treatment for COVID-19. Yet, blood products are important sources of HIV infection in low- and middle-income nations. Great care must be taken to prevent plasma therapy from fueling HIV epidemics in the developing world.

Potential benefits, mechanisms, and uncertainties of convalescent plasma therapy for COVID-19

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in China led to a public health emergency of international concern, putting all health organizations on high alert in the beginning of 2020. Corona virus disease 2019 (COVID-19) is highly infectious and has resulted in thousands of deaths which exceeded that of the SARS coronavirus (SARS-CoV) outbreak back in 2002 and 2003 in China. Besides, the number of diagnosed patients, patients who are suspected to have contracted the disease, and deaths are increasing worldwide. Unfortunately, effective drugs and vaccines to combat SARS-CoV-2 are still lacking. Convalescent plasma, a seemingly successful treatment for COVID-19 patients, proved to be of huge value in terms of saving severely ill patients. This review introduces the reported effects, potential mechanisms, and future uncertainties of convalescent plasma therapy in the treatment of COVID-19 patients, in the hopes that it will provide useful information for relevant physicians and researchers.

The Association of Increased FFP:RBC Transfusion Ratio to Primary Graft Dysfunction in Bleeding Lung Transplantation Patients

OBJECTIVES

Lung transplantation is associated with a significant risk of needed transfusion. Although algorithm-based transfusion strategies that promote a high fresh frozen plasma:red blood cells (FFP:RBC) ratio have reduced overall blood product requirements in other populations, large-volume transfusions have been linked to primary graft dysfunction (PGD) in lung transplantation, particularly use of platelets and plasma. The authors hypothesized that in lung transplant recipients requiring large-volume transfusions, a higher FFP:RBC ratio would be associated with increased PGD severity at 72 hours.

DESIGN

Observational retrospective review.

SETTING

Single tertiary academic center.

PARTICIPANTS

Adult patients undergoing bilateral or single orthotopic lung transplantation and receiving >4 U PRBC in the first 72 hours from February 2014 to March 2019.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patient demographics, operative characteristics, blood transfusions, and outcomes including PGD scores and length of stay were collected. Eighty-nine patients received >4U PRBC, had available 72-hour PGD data, and were included in the study. These patients were grouped into a high-ratio (>1:2 units of FFP:RBC, N = 38) or low-ratio group (<1:2 units of FFP:RBC, N = 51). Patients in the high-ratio group received more transfusions and factor concentrates and had significantly longer case length. The high-ratio group had a higher rate of severe PGD at 72 hours (60.5% v 23.5%, p = 0.0013) and longer hospital length of stay (40 v 32 days, p = 0.0273).

CONCLUSIONS

In bleeding lung transplantation patients at high risk for PGD, a high FFP:RBC transfusion ratio was associated with worsened 72-hour PGD scores when compared with the low-ratio cohort.

How 217 Pediatric Intensivists Manage Anemia at PICU Discharge: Online Responses to an International Survey

OBJECTIVE

To describe the management of anemia at PICU discharge by pediatric intensivists.

DESIGN

Self-administered, online, scenario-based survey.

SETTING

PICUs in Australia/New Zealand, Europe, and North America.

SUBJECTS

Pediatric intensivists.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Respondents were asked to report their decisions regarding RBC transfusions, iron, and erythropoietin prescription to children ready to be discharged from PICU, who had been admitted for hemorrhagic shock, cardiac surgery, craniofacial surgery, and polytrauma. Clinical and biological variables were altered separately in order to assess their effect on the management of anemia. Two-hundred seventeen responses were analyzed. They reported that the mean (± SEM) transfusion threshold was a hemoglobin level of 6.9 ± 0.09 g/dL after hemorrhagic shock, 7.6 ± 0.10 g/dL after cardiac surgery, 7.0 ± 0.10 g/dL after craniofacial surgery, and 7.0 ± 0.10 g/dL after polytrauma (p < 0.001). The most important increase in transfusion threshold was observed in the presence of a cyanotic heart disease (mean increase ranging from 1.80 to 2.30 g/dL when compared with baseline scenario) or left ventricular dysfunction (mean increase, 1.41-2.15 g/dL). One third of respondents stated that they would not prescribe iron at PICU discharge, regardless of the hemoglobin level or the baseline scenario. Most respondents (69.4-75.0%, depending on the scenario) did not prescribe erythropoietin.

CONCLUSIONS

Pediatric intensivists state that they use restrictive transfusion strategies at PICU discharge similar to those they use during the acute phase of critical illness. Supplemental iron is less frequently prescribed than RBCs, and prescription of erythropoietin is uncommon. Optimal management of post-PICU anemia is currently unknown. Further studies are required to highlight the consequences of this anemia and to determine appropriate management.

rIL-35 prevents murine transfusion-related acute lung injury by inhibiting the activation of endothelial cells

BACKGROUND

Transfusion-related acute lung injury (TRALI) is an important cause of death associated with transfusion, and no specific clinical treatments are available. Endothelial cells are believed to play an important role in the development of TRALI. This study investigated whether IL-35, an endothelial stabilizing cytokine could regulate the severity of antibody-mediated TRALI in vivo.

STUDY DESIGN AND METHODS

Human microvascular endothelial cells (HMVECs) were cultured in vitro, rIL-35(2 μg/mL) was added before HMVECs activation, and HMVECs were fully activated by LPS (0.5 μg/mL). Then cells were collected for flow cytometry analysis. We used a previously established "two-event" mouse model of TRALI with naive and lipopolysaccharide (LPS)-injected mice as controls. rIL-35(100 μg/kg) was injected into the tail vein for 3 consecutive days before the induction of the TRALI model. Samples were collected 2 hours after TRALI induction and tested for lung tissue myeloperoxidase activity, total protein levels, lung tissue histology, endothelial cell activation assay, and cytokine assay.

RESULTS

In vitro culture of HMVECs with rIL-35 verified that rIL-35 inhibited endothelial cells. In a mouse model, prophylactic administration of rIL-35 prevented pulmonary edema, increased lung protein levels, and reduced polymorphonuclear neutrophil accumulation in the lung.

CONCLUSIONS

This work suggests that antibody-mediated murine TRALI can be prevented by rIL-35, and that rIL-35 appears to work by inhibiting the activation of lung endothelial cells.

Post-Traumatic Sepsis Is Associated with Increased C5a and Decreased TAFI Levels

Background: Sepsis frequently occurs after major trauma and is closely associated with dysregulations in the inflammatory/complement and coagulation system. Thrombin-activatable fibrinolysis inhibitor (TAFI) plays a dual role as an anti-fibrinolytic and anti-inflammatory factor by downregulating complement anaphylatoxin C5a. The purpose of this study was to investigate the association between TAFI and C5a levels and the development of post-traumatic sepsis. Furthermore, the predictive potential of both TAFI and C5a to indicate sepsis occurrence in polytraumatized patients was assessed. Methods: Upon admission to the emergency department (ED) and daily for the subsequent ten days, circulating levels of TAFI and C5a were determined in 48 severely injured trauma patients (injury severity score (ISS) ≥ 16). Frequency matching according to the ISS in septic vs. non-septic patients was performed. Trauma and physiologic characteristics, as well as outcomes, were assessed. Statistical correlation analyses and cut-off values for predicting sepsis were calculated. Results: Fourteen patients developed sepsis, while 34 patients did not show any signs of sepsis (no sepsis). Overall injury severity, as well as demographic parameters, were comparable between both groups (ISS: 25.78 ± 2.36 no sepsis vs. 23.46 ± 2.79 sepsis). Septic patients had significantly increased C5a levels (21.62 ± 3.14 vs. 13.40 ± 1.29 ng/mL; p < 0.05) and reduced TAFI levels upon admission to the ED (40,951 ± 5637 vs. 61,865 ± 4370 ng/mL; p < 0.05) compared to the no sepsis group. Negative correlations between TAFI and C5a (p = 0.0104) and TAFI and lactate (p = 0.0423) and positive correlations between C5a and lactate (p = 0.0173), as well as C5a and the respiratory rate (p = 0.0266), were found. In addition, correlation analyses of both TAFI and C5a with the sequential (sepsis-related) organ failure assessment (SOFA) score have confirmed their potential as early sepsis biomarkers. Cut-off values for predicting sepsis were 54,857 ng/mL for TAFI with an area under the curve (AUC) of 0.7550 (p = 0.032) and 17 ng/mL for C5a with an AUC of 0.7286 (p = 0.034). Conclusion: The development of sepsis is associated with early decreased TAFI and increased C5a levels after major trauma. Both elevated C5a and decreased TAFI may serve as promising predictive factors for the development of sepsis after polytrauma.

Platelet depletion limits the severity but does not prevent the occurrence of experimental transfusion-related acute lung injury

BACKGROUND

Transfusion-related acute lung injury (TRALI) is a severe pulmonary reaction due to blood transfusions. The pathophysiology of this complication is still not widely elucidated by the scientific community, especially regarding the direct role of blood platelets within the cellular mechanism responsible for the development of TRALI.

STUDY DESIGN AND METHODS

In this study, a mouse model was used to induce the development of antibody-mediated acute lung injury through injections of lipopolysaccharide and an anti-major histocompatibility complex Class I antibody. BALB/c mice were pretreated with an anti-GPIbα antibody, which induces platelet depletion, or ML354, a protease receptor 4 pathway inhibitor, 30 minutes before TRALI induction.

RESULTS

Depletion of platelets before TRALI induction appeared to reduce the severity of TRALI without completely inhibiting its development. Also, inhibition of platelet activation by ML354 did not prevent the onset of TRALI. Finally, the stimuli used for TRALI induction also triggered specific platelet activation upon ex vivo stimulation.

CONCLUSIONS

This study suggests that blood platelets are not critically required for TRALI induction, although they are to some extent involved in its pathophysiology.

M1-polarized alveolar macrophages are crucial in a mouse model of transfusion-related acute lung injury

BACKGROUND

The pathogenesis of transfusion-related acute lung injury (TRALI) progress is incompletely understood, and specific therapies for TRALI are lacking. Alveolar macrophages (AMs) are critical for initiation and resolution of lung inflammation. However, the role of AMs in the pathogenesis of TRALI-associated lung failure is poorly understood.

STUDY DESIGN AND METHODS

Mouse model for in vivo imaging of interleukin (IL)-6 activation in AMs was established by intratracheal instillation of a lentiviral vector carrying the luciferase reporter gene. The TRALI mouse model was produced by intraperitoneal lipopolysaccharide plus intravenous major histocompatibility complex Class I monoclonal antibody treatment. We focused on the changes in AMs in the lung during TRALI and examined whether targeting AMs is an effective strategy to alleviate this condition.

MEASUREMENTS AND MAIN RESULTS

We confirmed that TRALI progress is accompanied by IL-6 activation in AMs. Further study showed that AMs undergo M1 activation during TRALI progress. AM depletion protected mice from TRALI, and transfusion of M1-polarized AMs into 34-1-2 s-treated mice elevated acute lung injury, indicating that the severity of TRALI was able to be ameliorated by targeting AM polarization. Next, we showed that α₁ -antitrypsin (AAT) expression improved lung injury by modulating the production of IL-6 in AMs and decreased polarization of AMs toward the M1 phenotype.

CONCLUSIONS

M1-polarized AMs are crucial in a mouse model of TRALI, and AAT may serve as a future treatment for TRALI by regulating the polarization of AMs.

Review of current transfusion therapy and blood banking practices

Transfusion Medicine is a dynamically evolving field. Recent high-quality research has reshaped the paradigms guiding blood transfusion. As increasing evidence supports the benefit of limiting transfusion, guidelines have been developed and disseminated into clinical practice governing optimal transfusion of red cells, platelets, plasma and cryoprecipitate. Concepts ranging from transfusion thresholds to prophylactic use to maximal storage time are addressed in guidelines. Patient blood management programs have developed to implement principles of patient safety through limiting transfusion in clinical practice. Data from National Hemovigilance Surveys showing dramatic declines in blood utilization over the past decade demonstrate the practical uptake of current principles guiding patient safety. In parallel with decreasing use of traditional blood products, the development of new technologies for blood transfusion such as freeze drying and cold storage has accelerated. Approaches to policy decision making to augment blood safety have also changed. Drivers of these changes include a deeper understanding of emerging threats and adverse events based on hemovigilance, and an increasing healthcare system expectation to align blood safety decision making with approaches used in other healthcare disciplines.

The Role of Complement in Transfusion-Related Acute Lung Injury

Transfusion-related acute lung injury (TRALI) is a life-threatening complication of acute respiratory distress occurring within 6 hours of blood transfusion. TRALI is one of the leading causes of transfusion-related fatalities and specific therapies are unavailable. Neutrophils are recognized as the major pathogenic cells, whereas T regulatory cells and dendritic cells appear to be important for protection against TRALI. The pathogenesis, however, is complex and incompletely understood. It is frequently postulated that the complement system plays an important role in the TRALI pathogenesis. In this article, we assess the evidence regarding the involvement of complement in TRALI from both human and animal studies. We hypothesize about the potential connection between the complement system and neutrophils in TRALI. Additionally, we draw parallels between TRALI and other acute pulmonary disorders of acute lung injury and acute respiratory distress syndrome regarding the involvement of complement. We conclude that, even though a role for complement in the TRALI pathogenesis seems plausible, studies investigating the role of complement in TRALI are remarkably limited in number and also present conflicting findings. Different types of TRALI animal models, diverse experimental conditions, and the composition of the gastrointestinal microbiota may perhaps all be factors which contribute to these discrepancies. More systematic studies are warranted to shed light on the contribution of the complement cascade in TRALI. The underlying clinical condition of the patient, which influences the susceptibility to TRALI, as well as the transfusion factor (antibody-mediated vs non–antibody-mediated), will be important to take into consideration when researching the contribution of complement. This should significantly increase our understanding of the role of complement in TRALI and may potentially result in promising new treatment strategies.

•

Studies investigating complement and TRALI are limited in number and present conflicting findings.

•

Systematic investigation is needed to better understand the contribution of the complement cascade in TRALI.

•

Future studies in this area should consider both the clinical susceptibility of the patient as well as the effect of transfusion factors.

Risk factors, management and prevention of transfusion-related acute lung injury: a comprehensive update

Introduction: Despite mitigation strategies that include the exclusion of females from plasma donation or the exclusion of females with a history of pregnancy or known anti-leukocyte antibody, transfusion-related acute lung injury (TRALI) remains a leading cause of transfusion-related morbidity and mortality. Areas covered: The definition of TRALI is discussed and re-aligned with the new Berlin Diagnostic Criteria for the acute respiratory distress syndrome (ARDS). The risk factors associated with TRALI are summarized as are the mitigation strategies to further reduce TRALI. The emerging basic research studies that may translate to clinical therapeutics for the prevention or treatment of TRALI are discussed. Expert opinion: At risk patients, including the genetic factors that may predispose patients to TRALI are summarized and discussed. The re-definition of TRALI employing the Berlin Criteria for ARDS will allow for increased recognition and improved research into pathophysiology and mitigation to reduce this fatal complication of hemotherapy.

Osteopontin mediates murine transfusion-related acute lung injury via stimulation of pulmonary neutrophil accumulation

Transfusion-related acute lung injury (TRALI) is one of the leading causes of transfusion-related fatalities and is characterized by the onset of acute respiratory distress within 6 hours upon blood transfusion. Specific therapies are unavailable. Preexisting inflammation is a risk factor for TRALI and neutrophils (polymorphonuclear neutrophils [PMNs]) are considered to be the major pathogenic cells. Osteopontin (OPN) is a multifunctional protein expressed at sites of inflammation and, for example, is involved in pulmonary disorders, can regulate cellular migration, and can function as a PMN chemoattractant. We investigated whether OPN is involved in TRALI induction by promoting PMN recruitment to the lungs. Using a previously established murine TRALI model, we found that in contrast to wild-type (WT) mice, OPN knockout (KO) mice were resistant to antibody-mediated PMN-dependent TRALI induction. Administration of purified OPN to the OPN KO mice, however, restored the TRALI response and pulmonary PMN accumulation. Alternatively, blockade of OPN in WT mice using an anti-OPN antibody prevented the onset of TRALI induction. Using pulmonary immunohistochemistry, OPN could be specifically detected in the lungs of mice that suffered from TRALI. The OPN-mediated TRALI response seemed dependent on macrophages, likely the cellular source of OPN and OPN polymerization, and independent from the OPN receptor CD44, interleukin 6 (IL-6), and other PMN chemoattractants including macrophage inflammatory protein-2 (MIP-2). These data indicate that OPN is critically required for induction of antibody-mediated murine TRALI through localization to the lungs and stimulation of pulmonary PMN recruitment. This suggests that anti-OPN antibody therapy may be a potential therapeutic strategy to explore in TRALI patients.

Noninfectious transfusion-associated adverse events and their mitigation strategies

Blood transfusions are life-saving therapies; however, they can result in adverse events that can be infectious or, more commonly, noninfectious. The most common noninfectious reactions include febrile nonhemolytic transfusion reactions, allergic transfusion reactions, transfusion-associated circulatory overload, transfusion-related acute lung injury, and acute and delayed hemolytic transfusion reactions. These reactions can be asymptomatic, mild, or potentially fatal. There are several new methodologies to diagnose, treat, and prevent these reactions. Hemovigilance systems for monitoring transfusion events have been developed and demonstrated decreases in some adverse events, such as hemolytic transfusion reactions. Now vein-to-vein databases are being created to study the interactions of the donor, product, and patient factors in the role of adverse outcomes. This article reviews the definition, pathophysiology, management, and mitigation strategies, including the role of the donor, product, and patient, of the most common noninfectious transfusion-associated adverse events. Prevention strategies, such as leukoreduction, plasma reduction, additive solutions, and patient blood management programs, are actively being used to enhance transfusion safety. Understanding the incidence, pathophysiology, and current management strategies will help to create innovative products and continually hone in on best transfusion practices that suit individualized patient needs.