Inhaled aerosolized nicotine suppresses the lung eosinophilic response to house dust mite allergen.

Introduction:
This article explores the impact of aerosolized nicotine (aeroNic) on the lung immune response, specifically focusing on its ability to suppress the eosinophilic response to house dust mite allergen. The study also investigates the potential signaling mechanisms through which nicotine interacts with nicotinic acetylcholine receptors (naChRs) expressed by alveolar macrophages (aM) and how activation with PaMs modulates responsiveness to an allergen. Understanding these interactions can provide insights into the effects of aerosolized nicotine on lung health and allergic responses.

Key Points:

* The study used mice exposed to aeroNic or aerosolized water (aeroW) as controls. Nicotine exposure was maintained during sensitization and challenge with house dust mite allergen (hDM).
* aerosolized nicotine inhibited the hDM-induced eosinophil response in a dose-dependent manner, while oral nicotine had no significant effect.
* Enhanced alveolar macrophage granularity was observed in mice exposed to aeroNic.
* aeroNic appeared to be substantially more effective than oral nicotine in suppressing the EOS response to an inhaled hDM allergen.
* aM expression of Ccl24 corresponded to the magnitude of the EOS response following hDM challenge, and this was modulated through naChRs.
* The type-2 PaM, PNU-120596, and two type-1 PaMs, NS-1738 and aVL-3288, greatly diminished the hDM EOS response when administered before each hDM challenge.
* The type-1 PaMs demonstrated a strong dose-dependent inhibition of Ccl24 transcription, with NS-1738 being more potent than aVL-3288.
* The presence of type-1 PaMs was sufficient to produce activation of naChRs leading to suppression of IL-4/10-induced signaling in aM.

Main Message:
The study demonstrates that aerosolized nicotine suppresses the lung eosinophilic response to house dust mite allergen, potentially through the activation of naChRs expressed by alveolar macrophages. This finding suggests that the allergic response may be substantially modified in electronic nicotine delivery systems (ENDS) users. however, the study also highlights the importance of understanding the complex interplay between nicotine, naChRs, and lung immune responses, as the consequences of self-administering unprecedented concentrations and purity of nicotine through ENDS are not yet fully understood.

Gahring LC, Myers EJ, Rogers SW. Inhaled aerosolized nicotine suppresses the lung eosinophilic response to house dust mite allergen. american journal of physiology Lung cellular and molecular physiology. 2020;319(4):L683-L692. doi:10.1152/ajplung.00227.2020