Identification of neutrophil extracellular traps in the blood of patients with systemic inflammatory response syndrome

Abstract

Objective: Neutrophils are able to form 'neutrophil extracellular traps' (NETs), which they use to trap and kill pathogens such as bacteria and fungi at the foci of infection. This observational study investigated the presence of NETs in the blood from critically ill patients and healthy volunteers. Methods: Fluorescent triple-colour immunocytochemical analysis of blood smears collected from patients with systemic inflammatory response syndrome (SIRS; associated with various clinical conditions) who had been hospitalized in the intensive care unit, and healthy volunteers, was undertaken to identify NETs in the blood. Blood smears were stained for DNA, histone H1 and neutrophil elastase. Results: NETs were identified in 10 of 21 (47.6%) blood samples from the study group compared with none of the blood samples from eight healthy volunteers. Conclusion: These data suggest that fluorescent triple-colour immunocytochemical staining of NETs in the blood could be used to simplify the early identification of critically ill patients with SIRS.

The impact of trauma on neutrophil function

“…From these results, it has been inferred that NET formation occurs as part of the early inflammatory response to trauma [38]. However, in the absence of direct evidence showing that the cf-DNA measured in these studies was derived from activated neutrophils, only the work of Hamaguchi and colleagues [17] can support this claim.…”

“…Examples of these include the recent description of trauma-induced changes in the composition of the circulating neutrophil pool [16] and the observation that trauma serves as a stimulus for the generation of neutrophil extracellular traps [17]. Alongside these findings, it has become apparent through the use of proteomics and microRNA profiling that trauma has a significant impact upon neutrophil signalling [18][19][20].…”

“…Using DNA staining alongside antibodies specific for histone H1 and NE, Hamaguchi et al [17] detected NETs in blood smear samples obtained from patients following thermal or traumatic injury. In other studies, the measurement of circulating cell-free DNA (cf-DNA) has been used as a surrogate marker of NET formation [37,38].…”

“…Thus, circulating soluble factors are likely to be responsible at least in part for the induction of NET formation that occurs following traumatic injury [17,37]. Indeed, pre-treatment of SIRS plasma with antibodies against TNF-a, IL-1b and IL-8 was found to significantly reduce its ability to drive NET production [37].…”

La pêche miraculeuse des filets du neutrophile

“…Plus précisément, dans les modèles expérimentaux de sepsis, les NET s'accumulent au niveau des microcirculations pulmonaire et hépatique, conduisant à une insuffisance hépatocellulaire aiguë et à un syndrome de détresse respiratoire aiguë par hypoperfusion [27]. Par ailleurs, chez l'homme, la présence de NET a été rapportée dans les prélèvements sanguins d'environ la moitié des patients atteints de sepsis sévère [28]. Au cours des pathologies pulmonaires inflammatoires aiguës comme le syndrome de détresse respiratoire aiguë ou le syndrome respiratoire aigu post-transfusionnel, les plaquettes activées induisent la formation de NET qui s'accumulent au niveau alvéolaire et participent aux lésions épithéliales et endothéliales.…”