Lung CD4⁺ resident memory T cells use airway secretory cells to stimulate and regulate neutrophilic allergic airways disease

ABSTRACT

Neutrophilic asthma is a vexing disease, but mechanistic and therapeutic advancement will require better models of allergy-induced airway neutrophilia. Here, we find that periodic ovalbumin (OVA) inhalation in sensitized mice elicits allergic airway inflammation and pathophysiology mimicking neutrophilic asthma. OVA-experienced murine lungs harbor diverse clusters of CD4⁺ resident memory T_RM cells, including unconventional RORγt^negative/low T_H17 cells. Acute OVA challenge instigates IL-17A secretion from these T_RM cells, driving CXCL5 production from Muc5ac^high airway secretory cells, leading to destructive airway neutrophilia. The T_RM- and epithelial-cell signals discovered herein are also observed in adult human asthmatic airways. Epithelial antigen presentation regulates this biology by skewing T_RM cells towards T_H2 and T_H1 fates, so that the T_H1-related IFN-γ suppresses IL-17A-driven, CXCL5-mediated airway neutrophilia. Concordantly, in vivo IFN-γ supplementation improves disease outcomes. Thus, using our model of neutrophilic asthma we identify lung epithelial-CD4⁺ T_RM cell crosstalk as a key rheostat of allergic airway neutrophilia.