Novel Analysis Methods for Longitudinal Cytokine Response Data in a Birth Cohort Study

Abstract

M O N D A Y 750 Cysteine Proteases Induce Production and Extracellular Release of IL-33 in Airway Epithelial Cells S. Seno, K. Iijima, S. M. O’Grady, H. Kita; Mayo Clinic, Rochester, MN, Department of Otorhinolaryngology, Shiga University of Medical Science, Otsu, JAPAN, Departments of Integrated Biology and Physiology and Animal Science, University of Minnesota, St. Paul, MN. RATIONALE: Interleukin (IL)-33 plays a pivotal role in T helper (Th) 2-type immune responses. IL-33 is constitutively expressed and stored in the nucleus of airway epithelial cells and is considered an ‘‘alarmin’’, which is released extracellularly when cells are damaged. Little is known regarding the mechanisms involved in production and secretion of IL-33. METHODS: Normal human bronchial epithelial (NHBE) cells were cultured with cysteine proteases (bromelain, papain) or extracts of house dust mite (HDM) in vitro. Na€ive non-sensitized mice were exposed to cysteine proteases in vivo. The mechanisms were studied by pharmacologic inhibitors and small interfering RNA (siRNA). RESULTS: NHBE cells constitutively expressed mRNA and produced protein for IL-33; IL-33 was localized mainly in the nucleus of resting cells. Cysteine proteases at low concentrations (e.g. 0.1 mg/ml) did not affect production but induced extracellular release of IL-33 within 2 h. In contrast, these cysteine proteases at high concentrations (e.g. 50 mg/ ml) enhanced IL-33 production. Similarly, HDM extracts induced IL-33 release, which is dependent on extracts’ cysteine protease activities. Pharmacologic inhibitors and siRNAs for a protease receptor (PAR2) and a purinergic receptor (P2Y2) attenuated both IL-33 production and release induced by cysteine proteases. Airway exposure of mice to cysteine proteases enhanced production of IL-33 in vivo. CONCLUSIONS: Production and extracellular release of IL-33 by airway epithelial cells is upregulated by exposure to cysteine proteases through receptors sensing protease activities and cellular stress. Cysteine protease activities in allergens may play important roles in promoting Th2-type immune responses in the airway.