IL-4Rα signs mg in CD4+CD25+FoxP3+ T regulatory cells restrains airway inflammation via limiting local tissue IL-33

Impaired tolerance to innocuous particles during allergic asthma has been linked to increased plasticity of FoxP3(+) regulatory T cells (Tregs) reprogramming into pathogenic effector cells, thus exacerbating airway disease. However, failure of tolerance mechanisms is driven by Th2 inflammatory signals. Therefore, the in vivo role of canonical IL-4 receptor alpha (IL-4R alpha) signaling, an essential driver of Th2-type airway responses to allergens, on the regulatory function of FoxP3(+) Tregs in allergic asthma was explored. Here, we used transgenic Foxp3(cre)IL-4R alpha(-/lox) and littermate control mice to investigate the role of IL-4 and IL-13 signaling via Tregs in house dust mite-induced (HDM-induced) allergic airway disease. We sensitized mice intratracheally on day 0, challenged them on days 6-10, and analyzed airway hyperresponsiveness (AHR), airway inflammation, mucus production, and cellular profile on day 14. In the absence of IL-4R alpha responsiveness on FoxP3(+) Tregs, exacerbated AHR and airway inflammation were shown in HDM-sensitized mice. Interestingly, reduced induction of FoxP3(+) Tregs accompanied increased IL-33 alarmin production and type 2 innate lymphoid cell activation in the lung, exacerbating airway hyperreactivity and lung eosinophilia. Taken together, our findings indicate that IL-4R alpha-unresponsive FoxP3(+) Tregs result in exaggerated innate Th2-type, IL-33-dependent airway inflammation and a break intolerance during allergic asthma.