IL4 and asthma: Asthma has been initially believed to be a disorder of inflammation.3 In asthmatic patients, inflammatory cytokines like interleukin-4 (IL-4), IL-5, and IL-13 are altered along with asthma exacerbation.4 Similarly, BD patients are found to have dysfunction of inflammation when the disease is aggravated or subsides.5,6 Alterations of IL-4, IL-6, and IL-12 have been proven in BD patients under different emotional states.7–9 As such, some researchers suggest that these 2 diseases at least share similar mechanisms in their pathophysiology.10