Activation of lung megakaryocyte α7 nAChR exacerbates allergic airway inflammation via IL-33/p38 MAPK signaling.

Abstract

The cholinergic antiinflammatory pathway attenuates lung inflammation via the α7 nicotinic acetylcholine receptor (α7 nAChR) on immune cells. However, the role of α7 nAChR on lung megakaryocytes (Mks) in allergic airway inflammation remains unknown. In this study, allergen-challenged mouse models were used with conditional Mk-specific Chrna7 knockout, pharmacological activation (GTS-21), and Mk reconstitution. IL-33 expression and p38 MAPK signaling were assessed. We found that allergen challenge upregulated α7 nAChR specifically in lung Mks. Mk-specific Chrna7 deletion significantly alleviated allergic airway inflammation, whereas GTS-21 exacerbated inflammation via an Mk-dependent mechanism. Reconstitution with α7 nAChR+ Mks restored airway inflammatory responses. Mechanistically, α7 nAChR activation promoted Mk IL-33 synthesis and secretion through p38 MAPK signaling. Taken together, our results show that α7 nAChR on lung Mks plays a proinflammatory role in allergic airway inflammation, challenging its classical antiinflammatory paradigm and revealing pathogenic mechanisms.