Understanding the role of neutrophils in acute respiratory distress syndrome

Abstract

Acute respiratory distress syndrome (ARDS) is difficult to treat and is associated with a high mortality rate. The most severe form of coronavirus disease 2019 (COVID-19) also leads to life-threatening ARDS. Neutrophil counts are positively correlated with disease severity in ARDS. Neutrophil activation not only plays a significant role in immune defense against infections, but also causes tissue damage and leads to inflammatory diseases. Activated neutrophils rapidly migrate to inflamed lung tissue, releasing toxic granular contents and generating neutrophil extracellular traps. In the last few decades, it has become apparent that neutrophils occupy a central role in ARDS pathology. In this review, we summarize the neutrophil inflammatory responses and their relationships to ARDS. According to the current literature, understanding the function of neutrophils may be helpful in the treatment of ARDS.

Keywords: ARDS; Inflammation; Neutrophil.

Fig. 1

Schematic diagram of neutrophil-mediated lung injury. Neutrophils migrate to inflamed lung tissue. This is followed by respiratory burst, degranulation, and NET formation in an injured alveolus. These immune responses lead to bronchial epithelial damage, cell debris production from dying cells attracting more immune cells, and endothelium dysfunction causing widening of edematous interstitium, further impairing oxygenation.