Abstract

The alarmin cytokine IL-33 is a strong inducer of type two inflammation and has been implicated in various chronic lung diseases. Although much work has been done to understand the inflammatory effects of extracellular IL-33, there is still a knowledge gap in understanding how this cytokine is secreted by airway epithelial cells in steady-state conditions. In the work laid out in this document, a COPD-disease associated isoform of IL-33, that has exons 3 and 4 (IL-3334) spliced out and is tonically secreted at baseline conditions. This IL-33 isoform is secreted from airway epithelial cells alongside, or as part of, extracellular vesicles that arise from nSmase2-driven ceramide generation at the endosomal membrane whose contents are then secreted upon fusion to the plasma membrane. The main goal of this project was to uncover the mechanism through which IL-3334 is recruited to the nSmase2-dependent exosome biogenesis pathway. HSP70, the stress induced molecular chaperone, binds to IL-33 and chaperones it to a secretory membranous compartment, reminiscent of a microautophagy mechanism. IL-3334 also binds to the negatively charged lipid phosphatidyl serine which HSP70 may potentiate or enhance. Outside of the cell, this HSP70/cytokine complex stabilizes IL-3334 by inhibiting oxidation/degradation, thereby enhancing IL-3334-receptor binding and activity. We find evidence that IL-33, HSP70, HSP90 and proteostasis chaperonin TCP-1 are dysregulated in human chronic airway disease biospecimens. A significant portion of this work also delved into developing the tools and methodology to study the contributions of extracellular vesicles in airway disease. This molecular chaperone dysregulation phenomenon is also reflected in the differential proteomics in diseased bronchial wash extracellular vesicles which opens opportunities to track EV-mediated communication in vivo and in human derived biospecimens. These platforms can be applied to interrogate the functional roles of EVs, molecular chaperones and noncanonical IL-33 signaling in modulating immune responses, propagating inflammation, or contributing to airway remodeling in chronic lung diseases such as asthma and COPD. This work confirms proteostasis intermediates, chiefly HSP70 as a chaperone for non-canonical IL-3334 secretion and activity that may be amenable for therapeutic targeting in chronic airway diseases such as asthma and COPD.

Committee Chair

Jennifer Alexander-Brett

Committee Members

Deborah Lenschow; Claire Crewe; Benjamin Garcia, Andrew Kau, Steven Van Dyken

Degree

Doctor of Philosophy (PhD)

Author's Department

Biology & Biomedical Sciences (Immunology)

Author's School

Graduate School of Arts and Sciences

Document Type

Dissertation

Date of Award

8-19-2025

Language

English (en)

Author's ORCID

https://orcid.org/0000-0002-6571-3162

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