Indeed, in mice, those with obesity caused by diet or genetic factors showed exacerbation of AHR and neutrophilic airway inflammation with increasing expression of IL-17A in the lung (18, 75, 76) and Th17 lymphocytes, suggesting that type 3 innate lymphoid cells might be responsible for worsening the AHR and airway inflammation in such animals (77, 78). The gene discussed is IL17A; the disease is obesity due to melanocortin 4 receptor deficiency.