Multifaceted functions of SiglecF expressing neutrohpils in the exacerbation of air pollutant-induced airway inflammation

Diesel exhaust particles (DEPs) are the main component of traffic-related air pollution and implicated in asthma pathogenesis and exacerbation. However, the mechanistic link between DEP exposure and worsening asthma symptoms remains unclear. Here, we characterized a unique subset of neutrophils that express a high level of Sialic acid-binding, Ig-like lectin (Siglec)-F. DEP exposure instructs SiglecF expression on neutrophils by increasing P2X1 receptors sensing damage-associated molecular patterns (DAMPs) molecules, ATP. SiglecFhigh neutrophils stimulated by DEP release neutrophil extracellular traps (NETs) to cause tissue damage and IL-17A production, and potentiated type 2 cytokine production by producing cysteinyl leukotrienes. As a result, SiglecFhigh neutrophils worsen airway hyperresponsiveness (AHR) as well as airway inflammations. We also confirmed that siglec8, corresponding to murine SiglecF, expression increased in neutrophils from patients with asthma, and they correlated with the severity of the disease. Together, these translational findings suggest a novel SiglecF expressing neutrophils in the development of severe asthma by linking type 2 and type 3 responses. mRNA profiles of Eosinophils (1), SiglecFlow (2) and SiglecFhigh (2) neutrophils sorted from DEP exposed wild type lungs