Neutrophil extracellular traps in ex vivo lung perfusion perfusate predict the clinical outcome of lung transplant recipients

Abstract

Neutrophil extracellular traps in ex vivo lung perfusion perfusate predict the clinical outcome of lung transplant recipients To the Editor: Lung transplantation is lifesaving for patients with end-stage lung diseases. However, a scarcity of donor lungs suitable for transplantation limits the number of procedures that can be performed. Furthermore, major obstacles to successful lung transplantation still exist; primary graft dysfunction (PGD), the leading cause of early morbidity and mortality post-lung transplant, develops in ∼15-30% of recipients [1]. Normothermic ex vivo lung perfusion (EVLP) maintains donor lungs in a physiological state through perfusion and ventilation, so that the lungs can be assessed, treated and accepted for transplantation, thereby increasing the donor pool and alleviating the severe shortage of viable donor lungs [2]. In addition to donor lung assessment, EVLP provides a unique platform to study cellular processes occurring in donor lungs. EVLP perfusate is a unique, noninvasive source of biological sampling, which offers valuable information about the state of the donor lung. Rapid, molecular diagnostic testing could be an important addition to assessment of donor lungs, and may help improve outcome [3-7]. Detection of injurious markers in EVLP perfusate may also help inform future targeted treatments for the lungs, which could be administered directly to the organ through the EVLP circuit. In order to develop a reliable molecular assessment of donor lungs, a stable, easily quantifiable biomarker that reflects donor lung injury is required. Neutrophil extracellular traps (NETs) are structures comprised of extracellular neutrophil DNA in a complex with antimicrobial granular proteins, such as neutrophil elastase (NE) and myeloperoxidase. Neutrophils form NETs in response to innate immune challenges. Although NETs are generally considered antibacterial, several recent studies suggest that the cytotoxicity of NETs can be highly detrimental to lung and other tissue through complement activation, exposed histone cytotoxicity, promotion of thrombosis, and propagation of neutrophil recruitment and activation [8-11]. NETs have been specifically implicated in a variety of lung disease and injury states, including ventilator-induced lung injury and PGD [12, 13]. NETs play an important role in lung injury, but their role in lung transplantation is largely unknown. As NETs are a quantifiable measure of the innate immune response to a variety of inflammatory stimuli, this study aimed to determine whether NETs are detectable in EVLP perfusate, indicating their production by neutrophils in donor lungs. Furthermore, this study assessed the ability of NETs to serve as a relevant biomarker of donor lung injury. We report that elevated NET levels in donor lung EVLP perfusate are associated with worse recipient outcomes. Written, informed consent was obtained, and this study was approved by the University Health Network Research Ethics Board. Clinical perfusate samples from consecutive EVLP cases that w...

Effects of cold or warm ischemia and ex-vivo lung perfusion on the release of damage associated molecular patterns and inflammatory cytokines in experimental lung transplantation

“…Recent data support a key role of S100A8 in sterile inflammation after myocardial ischemiareperfusion (40). Our findings suggests that S100A8 conveys similar pro-inflammatory actions in early reperfusion after LTx following EVLP, which could reflect the activation of donor lung leukocytes during EVLP (41). On a clinical standpoint, this hypothesis should be evaluated by measuring S100A8 release following LTx after EVLP, as this could lead to potential therapeutic implications aimed at interfering with S100A8 (28,40).…”

Endothelin receptor antagonist improves donor lung function in an ex vivo perfusion system

“…EVLP perfusate, a sampling source to assess the lung during EVLP, offers valuable information about the condition of the donor lung [39][40][41][42][43]. Detection of lung injury markers in the perfusate may also help finding future targeted treatments that could be administered directly to the lungs through the EVLP circuit [44]. Several studies have reported the use of the EVLP system as a device for direct pharmacologic graft intervention in large-animal models [45][46][47][48] and in patients [49,50].…”

Treatment with 3-aminobenzamide during ex vivo lung perfusion of damaged rat lungs reduces graft injury and dysfunction after transplantation

“…It is well established that PMNs recruited within the lung allograft represent crucial cellular effectors of PGD . PMNs within the transplanted lungs may arise from two distinct sources, the first one being the donor lung itself, which possesses an important reservoir of marginated neutrophils, forming highly toxic NETs (neutrophil extracellular traps) and being immediately recruitable upon transplantation, and the second one being the circulating PMNs from the recipient . The latter pool of PMNs infiltrate the graft upon interaction between leukocyte‐derived integrins with selectins and adhesion molecules expressed by the endothelium in the donor lung .…”