Project Summary/Abstract The goal of this proposal is to determine the regulation and functions of immunoproteasome (IP) during rhinovirus infection in airways with type 2 inflammation, a hallmark of the type 2 (e.g., interleukin 13 [IL-13]) high asthma. Rhinovirus (RV) infection remains a significant healthcare burden due to its contribution to exacerbations of asthma and other lung diseases. Because there is no effective therapy for airway RV infection, it is imperative to define novel mechanisms (e.g., IP) that clear RV from the infected airway cells (e.g., epithelial cells). We found reduced IP expression in airway epithelial cells of severe asthma patients with airway type 2 inflammation. Importantly, our preliminary data strongly suggest that IP expression in human primary airway epithelial cells was significantly up-regulated by RV (RV-A and RV-C) infection, and that knockout or inhibition of key IP components (e.g., LMP2 and LMP7) increased airway epithelial viral load. Type 2 cytokine IL-13 significantly reduced IP induction by RV. RV-infected LMP2 knockout (vs. wild-type) mice were unable to clear the viruses effectively, and increased lung inflammation. We will test the hypothesis that airway IP induction during RV infection serves as a critical host defense mechanism to eliminate viral infection, but is impaired in airways with type 2 inflammation, leading to persistent infection and excessive inflammation. In Aim 1, we will determine the role of the interferons (IFNs)/IFN receptor (IFNR)/STAT1 axis in IP regulation by RV and type 2 inflammation by performing gene knockout experiments in human primary airway epithelial cells, and using the human precision- cut lung slices or gene (e.g., IFNAR or STAT1) deficient mice exposed to IL-13, allergen and/or RV. In Aim 2, we will determine the role of IP in RV-mediated asthma exacerbation and underlying mechanisms by using IP deficient mice (whole body or airway epithelial conditional gene knockout) and human primary airway epithelial cells with IP gene knockout. We will test if IP’s antiviral and anti-inflammatory functions depend on its regulation of RV 3C protease and A20, a negative immune regulator. In Aim 3, we will determine the efficacy of IP as an antiviral agent in airways with type 2 inflammation. By delivering a single low-dose of IFN-l or a viral mimic (i.e., polyI:C) into cultured human airway epithelium or mouse airways with type 2 inflammation, we will test if enhancing IP expression promotes resolution of airway acute RV infection and inflammation. Research findings will significantly improve our understanding about host defense mechanisms against RV infection, and likely provide a new opportunity to treat RV infections in patients with asthma and other diseases.