IL9 and chronic obstructive pulmonary disease: Asthma, Allergic rhinitis (AR), Chronic Obstructive Pulmonary Disease (COPD), Eczema, and Chronic Rhinosinusitis with Sinonasal Polyposis (CRSwNP) are illnesses often characterized by type 2 (T2) inflammation, wherein T helper (Th) cells release pro-inflammatory cytokines such as IL (interleukin)-4, IL-5, IL-9, and IL-13.