Neutrophil Heterogeneity in Airway Inflammatory Diseases

Neutrophils, the most abundant circulating leukocytes in humans, play key roles in infection and inflammation. The lungs represent a vital pool for neutrophils, serving as both a primary site of immune surveillance and a key battleground in inflammatory responses. However, neutrophil activation could be harmful; excessive or prolonged neutrophil activity can lead to unintended tissue damage and contribute to disease progression. Increasing evidence has highlighted the multifaceted roles of neutrophils in the pathogenesis and progression of airway inflammatory diseases. This review aims to elaborate the current understanding of neutrophil heterogeneity, functions, and mechanisms in various airway inflammatory diseases, including acute respiratory distress syndrome (ARDS), asthma, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis. Understanding the precise contributions of neutrophils in those airway inflammatory diseases would provide valuable insights into the complex immune landscape of the lungs and might open new avenues for targeted therapeutics.