Correlation between Neutrophil Extracellular Traps (NETs) Expression and Primary Graft Dysfunction Following Human Lung Transplantation

Abstract

Primary graft dysfunction (PGD) is characterized by alveolar epithelial and vascular endothelial damage and inflammation, lung edema and hypoxemia. Up to one-third of recipients develop the most severe form of PGD (Grade 3; PGD3). Animal studies suggest that neutrophils contribute to the inflammatory process through neutrophil extracellular traps (NETs) release (NETosis). NETs are composed of DNA filaments decorated with granular proteins contributing to vascular occlusion associated with PGD. The main objective was to correlate NETosis in PGD3 (n = 9) versus non-PGD3 (n = 27) recipients in an exploratory study. Clinical data and blood samples were collected from donors and recipients pre-, intra- and postoperatively (up to 72 h). Inflammatory inducers of NETs’ release (IL-8, IL-6 and C-reactive protein [CRP]) and components (myeloperoxidase [MPO], MPO-DNA complexes and cell-free DNA [cfDNA]) were quantified by ELISA. When available, histology, immunohistochemistry and immunofluorescence techniques were performed on lung biopsies from donor grafts collected during the surgery to evaluate the presence of activated neutrophils and NETs. Lung biopsies from donor grafts collected during transplantation presented various degrees of vascular occlusion including neutrophils undergoing NETosis. Additionally, in recipients intra- and postoperatively, circulating inflammatory (IL-6, IL-8) and NETosis biomarkers (MPO-DNA, MPO, cfDNA) were up to 4-fold higher in PGD3 recipients compared to non-PGD3 (p = 0.041 to 0.001). In summary, perioperative elevation of NETosis biomarkers is associated with PGD3 following human lung transplantation and these biomarkers might serve to identify recipients at risk of PGD3 and initiate preventive therapies.

Plasma from patients undergoing allogeneic hematopoietic stem cell transplantation promotes NETOSIS in vitro and correlates with inflammatory parameters and clinical severity

“…Similar results were published by Bonneau et al. ( 29 ) that reported higher circulating inflammatory cytokines (IL-6 and IL-8) and NETosis biomarkers in the setting of primary graft dysfunction after lung transplantation. In fact, although NETosis and NET generation are important for preventing pathogen invasion, their excessive formation can result in a slew of negative consequences, such as autoimmunity, inflammation and tissue damage ( 30 – 32 ).…”

Predicting Primary Graft Dysfunction in Lung Transplantation: Machine Learning–Guided Biomarker Discovery

“…Analysis of plasma samples at individual time points revealed over 15 analytes were significantly different between PGD+ and PGD-patients. Several of these, including IL-6 and MCP-1, align with plasma biomarkers of PGD+ previously reported, while others are original findings (Hoffman et al 2009;Bharat et al 2008;Shah et al 2012;Bonneau et al 2022;Moreno et al 2007). Of note, BCA-1 (CXCL13) and IL-22 were significantly elevated in PGD+ plasma compared to PGD-plasma in a multivariate analysis of all time points analyzed.…”

Low density neutrophils and neutrophil extracellular traps (NETs) are new inflammatory players in heart failure

“…In a recent study, we found that patients undergoing lung transplants with stage 3 primary graft dysfunction (PGD3) had increased NETosis biomarkers (MPO-DNA, MPO, and cfDNA) and pro-inflammatory cytokines (IL-8 and IL-6) correlating with severe graft dysfunction. In addition, as depicted by immunofluorescence staining, we observed in some of the lung graft tissues prior to transplantation, microvascular occlusion mainly derived from neutrophils undergoing NETosis and platelet-bound neutrophils adhered onto lung endothelium 34 .…”