The specific roles of IL-33, together with other epithelial-derived alarmins such as IL-25 and thymic stromal lymphopoietin, in sustaining chronic airway inflammation in diseases like asthma and COPD, as well as the degree to which these alarmins overlap or compensate for one another, remain active areas of research [173]. This evidence concerns the gene IL25 and chronic obstructive pulmonary disease.