Acute Respiratory Distress Syndrome Neutrophils Have a Distinct Phenotype and Are Resistant to Phosphoinositide 3-Kinase Inhibition

Abstract

Rationale: Acute respiratory distress syndrome is refractory to pharmacological intervention. Inappropriate activation of alveolar neutrophils is believed to underpin this disease's complex pathophysiology, yet these cells have been little studied.Objectives: To examine the functional and transcriptional profiles of patient blood and alveolar neutrophils compared with healthy volunteer cells, and to define their sensitivity to phosphoinositide 3-kinase inhibition.Methods: Twenty-three ventilated patients underwent bronchoalveolar lavage. Alveolar and blood neutrophil apoptosis, phagocytosis, and adhesion molecules were quantified by flow cytometry, and oxidase responses were quantified by chemiluminescence. Cytokine and transcriptional profiling were used in multiplex and GeneChip arrays.Measurements and Main Results: Patient blood and alveolar neutrophils were distinct from healthy circulating cells, with increased CD11b and reduced CD62L expression, delayed constitutive apoptosis, and primed oxidase responses. Incubating control cells with disease bronchoalveolar lavage recapitulated the aberrant functional phenotype, and this could be reversed by phosphoinositide 3-kinase inhibitors. In contrast, the prosurvival phenotype of patient cells was resistant to phosphoinositide 3-kinase inhibition. RNA transcriptomic analysis revealed modified immune, cytoskeletal, and cell death pathways in patient cells, aligning closely to sepsis and burns datasets but not to phosphoinositide 3-kinase signatures.Conclusions: Acute respiratory distress syndrome blood and alveolar neutrophils display a distinct primed prosurvival profile and transcriptional signature. The enhanced respiratory burst was phosphoinositide 3-kinase-dependent but delayed apoptosis and the altered transcriptional profile were not. These unexpected findings cast doubt over the utility of phosphoinositide 3-kinase inhibition in acute respiratory distress syndrome and highlight the importance of evaluating novel therapeutic strategies in patient-derived cells.

Neutrophil GM-CSF receptor dynamics in acute lung injury

“…Human peripheral blood neutrophils were isolated from adult healthy non‐medicated volunteers. Neutrophils were also isolated from the blood and the bronchoalveolar lavage fluid (BALF) of patients requiring mechanical ventilation for ARDS as previously detailed . All studies complied with the Declaration of Helsinki and were approved by the Cambridge Research Ethics Committee (08/H03306/17); written informed consent was obtained from all subjects or their legal surrogate.…”

“…Indeed, the extent and duration of alveolar airspace neutrophilia in ARDS is a strong predictor of outcome . Whereas the presence of neutrophils within an inflamed tissue does not mandate a pathogenic role for these cells, in ARDS we and others have shown that the neutrophils within the alveolar airspace have a highly primed and pro‐survival phenotype with enhanced superoxide anion and protease release, preserved neutrophil‐extracellular trap (NET) formation, and delayed apoptosis and as such are considered to be important drivers of lung injury.…”

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Clostridium butyricum Strains Suppress Experimental Acute Pancreatitis by Maintaining Intestinal Homeostasis

“…Innate immune cells including polymorphonuclear neutrophils, macrophages, and dendritic cells with distinct cell‐surface and intracellular markers are key players during the acute phase of the disease. Activation of these cells has been closely associated with the development and severity of acute inflammatory conditions …”