Extracellular Vesicle Sphingolipids from Stored Platelets Mediate Transfusion Related Acute Lung Injury
Bibliographic record
Abstract
BACKGROUND Transfusion‐related acute lung injury (TRALI) leads to chest infiltrates and hypoxia after 0.02–1% of transfusions with an associated mortality up to 15%. Sphingolipid ceramide weakens endothelial barriers while sphingosine‐1‐phosphate (S1P) is barrier protective. Aged stored platelets elicit TRALI by acid sphingomyelinase (ASM) dependent ceramide formation, which causes lung injury ( in vivo) and impairs pulmonary endothelial cell (EC) barrier integrity ( in vitro) . Concomitantly, aged platelets form extracellular vesicles (EVs) which can shuttle hydrophobic lipids such as sphingolipids to target cells. Combining these concepts, we hypothesized that 5‐day but not 1‐day stored platelets generate EVs which mediate TRALI in a sphingolipid‐dependent manner. METHODS EVs from male C57BL/6 wild type (WT) or Smpd1 −/− (ASM knockout) platelets stored for 1‐ or 5‐days duration were isolated by differential centrifugation and filtration prior to enumeration (flow cytometry) and sphingolipid analysis (mass spectroscopy). For TRALI induction, BALB/c male mice were primed with 2 mg/kg intraperitoneal lipopolysaccharide (LPS) two hours prior to intravenous infusion of 10 ml/kg EVs (≈ 5×10 6 ) or saline (sham) and were assessed (6 hours later) by measuring lung tissue wet‐to‐dry (W/D) weight ratios, bronchoalveolar lavage fluid protein (BAL‐p) and lung tissue myeloperoxidase activity (MPO). Transendothelial electrical resistance (TEER) was measured in cultured human microvascular pulmonary ECs treated with PBS (sham) or 5×10 5 EVs (from 1‐ vs 5‐day stored platelets) for 4 hours. RESULTS Compared with 1‐day EVs, 5‐day EVs were more numerous, ceramide enriched and S1P depleted. 5‐day EVs from ASM KO platelets were less numerous than 5‐day WT EVs, but had similar sphingolipid profiles. LPS primed mice receiving 5‐day EVs had increased W/D (p < 0.05), MPO and BAL‐p (p<0.05) relative to mice receiving LPS priming in addition to saline (sham), 1‐day EVs or ASM KO 5‐day EVs. 5‐day EVs but not 1‐day EVs led to reductions in TEER (< 2 hours) in vitro in keeping with EC loss of barrier integrity which persisted for > 4 hours. 5‐day EVs could be made to resemble 1‐day EVs (no injury) with addition of exogenous S1P at levels equivalent to those found in 1‐day EVs. CONCLUSIONS Ceramide formation in aged platelets contributes to EV formation and impairs human EC barrier integrity resulting in TRALI. Removal or modification of aged EVs from stored platelets may prove a therapeutic option to reduce the risk of aged cellular blood products from causing TRALI. Support or Funding Information This work was jointly funded by Canadian Blood Services and the Canadian Institute of Health Research (CIHR). MJM is supported by a CIHR Vanier Scholarship This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".