Transfusion of 35-day-stored red blood cells does not alter lipopolysaccharide tolerance during human endotoxemia

Transfusion-Related Acute Lung Injury: 36 years of Progress (1985-2021)

The term transfusion-related acute lung injury (TRALI) was coined in 1985 to describe acute respiratory distress syndrome (ARDS) after transfusion, when another ARDS risk factor was absent; TRALI cases were mostly associated with donor leukocyte antibody. In 2001, plasma from multiparous donors was implicated in TRALI in a randomized controlled trial in Sweden. In 2003 and in many years thereafter, the FDA reported that TRALI was the leading cause of death from transfusion in the United States. In 2003, the United Kingdom was the first among many countries to successfully reduce TRALI using male-predominant plasma. These successes are to be celebrated. Nevertheless, questions remain about the mechanisms of non-antibody TRALI, the role of blood products in the development of ARDS in massive transfusion patients, the causes of unusual TRALI cases, and how to reduce inaccurate clinical diagnoses of TRALI in clinical practice. Regarding the latter, a study in 2013-2015 at 169 US hospitals found that many TRALI diagnoses did not meet clinical definitions. In 2019, a consensus panel established a more precise terminology for clinical diagnosis: TRALI type I and TRALI type II are cases where transfusion is the likely cause, and ARDS are cases where transfusion is not the likely cause. For accurate diagnosis using these clinical definitions, critical care expertise is needed to distinguish between permeability versus hydrostatic pulmonary edema, to determine whether an ARDS risk factor is present and, if so, whether respiratory function was stable within the 12 hours before transfusion.

Y-RNA subtype ratios in plasma extracellular vesicles are cell type- specific and are candidate biomarkers for inflammatory diseases

Major efforts are made to characterize the presence of microRNA (miRNA) and messenger RNA in blood plasma to discover novel disease-associated biomarkers. MiRNAs in plasma are associated to several types of macromolecular structures, including extracellular vesicles (EV), lipoprotein particles (LPP) and ribonucleoprotein particles (RNP). RNAs in these complexes are recovered at variable efficiency by commonly used EV- and RNA isolation methods, which causes biases and inconsistencies in miRNA quantitation. Besides miRNAs, various other non-coding RNA species are contained in EV and present within the pool of plasma extracellular RNA. Members of the Y-RNA family have been detected in EV from various cell types and are among the most abundant non-coding RNA types in plasma. We previously showed that shuttling of full-length Y-RNA into EV released by immune cells is modulated by microbial stimulation. This indicated that Y-RNAs could contribute to the functional properties of EV in immune cell communication and that EV-associated Y-RNAs could have biomarker potential in immune-related diseases. Here, we investigated which macromolecular structures in plasma contain full length Y-RNA and whether the levels of three Y-RNA subtypes in plasma (Y1, Y3 and Y4) change during systemic inflammation. Our data indicate that the majority of full length Y-RNA in plasma is stably associated to EV. Moreover, we discovered that EV from different blood-related cell types contain cell-type-specific Y-RNA subtype ratios. Using a human model for systemic inflammation, we show that the neutrophil-specific Y4/Y3 ratios and PBMC-specific Y3/Y1 ratios were significantly altered after induction of inflammation. The plasma Y-RNA ratios strongly correlated with the number and type of immune cells during systemic inflammation. Cell-type-specific "Y-RNA signatures" in plasma EV can be determined without prior enrichment for EV, and may be further explored as simple and fast test for diagnosis of inflammatory responses or other immune-related diseases.

Ferroportin inhibition attenuates plasma iron, oxidant stress, and renal injury following red blood cell transfusion in guinea pigs

BACKGROUND

Red blood cell (RBC) transfusions result in the sequestration and metabolism of storage-damaged RBCs within the spleen and liver. These events are followed by increased plasma iron concentrations that can contribute to oxidant stress and cellular injury. We hypothesized that administration of a ferroportin inhibitor (FPN-INH) immediately after acute RBC exchange transfusion could attenuate posttransfusion circulatory compartment iron exposure, by retaining iron in spleen and hepatic macrophages.

STUDY DESIGN AND METHODS

Donor guinea pig blood was leukoreduced, and RBCs were preserved at 4°C. Recipient guinea pigs (n = 5/group) were exchange transfused with donor RBCs after refrigerator preservation and dosed intravenously with a small-molecule FPN-INH. Groups included transfusion with vehicle (saline), 5 mg/kg or 25 mg/kg FPN-INH. A time course of RBC morphology, plasma non-transferrin-bound iron (NTBI) and plasma hemoglobin (Hb) were evaluated. End-study spleen, liver, and kidney organ iron levels, as well as renal tissue oxidation and injury, were measured acutely (24-hr after transfusion).

RESULTS

RBC transfusion increased plasma NTBI, with maximal concentrations occurring 8 hours after transfusion. Posttransfusion iron accumulation resulted in tubule oxidation and acute kidney injury. FPN inhibition increased spleen and liver parenchymal/macrophage iron accumulation, but attenuated plasma NTBI, and subsequent renal tissue oxidation/injury.

CONCLUSION

In situations of acute RBC transfusion, minimizing circulatory NTBI exposure by FPN inhibition may attenuate organ-specific adverse consequences of iron exposure.

Red blood cell transfusion results in adhesion of neutrophils in human endotoxemia and in critically ill patients with sepsis

BACKGROUND

Red blood cell (RBC) transfusion is associated with adverse effects, which may involve activation of the host immune response. The effect of RBC transfusion on neutrophil Reactive Oxygen Species (ROS) production and adhesion ex vivo was investigated in endotoxemic volunteers and in critically ill patients that received a RBC transfusion. We hypothesized that RBC transfusion would cause neutrophil activation, the extent of which depends on the storage time and the inflammatory status of the recipient.

STUDY DESIGN AND METHODS

Volunteers were injected with lipopolysaccharide (LPS) and transfused with either saline, fresh, or stored autologous RBCs. In addition, 47 critically ill patients with and without sepsis receiving either fresh (<8 days) or standard stored RBC (2‐35 days) were included. Neutrophils from healthy volunteers were incubated with the plasma samples from the endotoxemic volunteers and from the critically ill patients, after which priming of neutrophil ROS production and adhesion were assessed.

RESULTS

In the endotoxemia model, ex vivo neutrophil adhesion, but not ROS production, was increased after transfusion, which was not affected by RBC storage duration. In the critically ill, ex vivo neutrophil ROS production was already increased prior to transfusion and was not increased following transfusion. Neutrophil adhesion was increased following transfusion, which was more notable in the septic patients than in non‐septic patients. Transfusion of fresh RBCs, but not standard issued RBCs, resulted in enhanced ROS production in neutrophils.

CONCLUSION

RBC transfusion was associated with increased neutrophil adhesion in a model of human endotoxemia as well as in critically ill patients with sepsis.

A comparison of different methods of red blood cell leukoreduction and additive solutions on the accumulation of neutrophil-priming activity during storage

BACKGROUND

Three methods of leukoreduction (LR) are used worldwide: filtration, buffy coat removal (BCR), and a combination of the previous two methods. Additionally, there are a number of additive solutions (ASs) used to preserve red blood cell (RBC) function throughout storage. During RBC storage, proinflammatory activity accumulates; thus, we hypothesize that both the method of LR and the AS affect the accumulation of proinflammatory activity.

STUDY DESIGN AND METHODS

Ten units of whole blood were drawn from healthy donors, the RBC units were isolated, divided in half by weight, and leukoreduced by: 1) BCR, 2) filtration, or 3) BCR and filtration (combination-LR); stored in bags containing AS-3 per AABB criteria; and sampled weekly. The supernatants were isolated and frozen (-80°C). RBC units drawn from healthy donors into AS-1-, AS-3-, or AS-5-containing bags were also stored and sampled weekly, and the supernatants were isolated and frozen. The supernatants were assayed for neutrophil (PMN)-priming activity and underwent proteomic analyses.

RESULTS

Filtration and combination LR decreased priming activity accumulation versus buffy coat LR, although the accumulation of priming activity was not different during storage. Combination LR increased hemolysis versus filtration via proteomic analysis. Priming activity from AS-3 units was significant later in storage versus AS-1- or AS-5-stored units.

CONCLUSIONS

Although both filtration and combination LR decrease the accumulation of proinflammatory activity versus buffy coat LR, combination LR is not more advantageous over filtration, has increased costs, and may cause increased hemolysis. In addition, AS-3 decreases the early accumulation of PMN-priming activity during storage versus AS-1 or AS-5.

Transfusion-related immunomodulation: a reappraisal

PURPOSE OF REVIEW

This review summarizes current and prior observations regarding transfusion-related immunomodulation (TRIM) and puts these ideas into a modern immunological context, incorporating concepts from innate, adaptive, and nutritional immunity. We propose that TRIM research focus on determining whether there are specific, well-defined immunosuppressive effects from transfusing 'pure' red blood cells (RBCs) themselves, along with the by-products produced by the stored RBCs as a result of the 'storage lesion.' Macrophages are a key cell type involved in physiological and pathological RBC clearance and iron recycling. The plasticity and diversity of macrophages makes these cells potential mediators of immune suppression that could constitute TRIM.

RECENT FINDINGS

Recent reports identified the capacity of macrophages and monocytes to exhibit 'memory.' Exposure to various stimuli, such as engulfment of apoptotic cells and interactions with ß-glucan and lipopolysaccharide, were found to induce epigenetic, metabolic, and functional changes in certain myeloid cells, particularly macrophages and monocytes.

SUMMARY

Macrophages may mediate the immunosuppressive aspects of TRIM that arise as a result of transfused RBCs and their storage lesion induced by-products.