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Epithelial IL-33 appropriates exosome trafficking for secretion in chronic airway disease
Ella Katz-Kiriakos, … , Mark J. Miller, Jennifer Alexander-Brett
Ella Katz-Kiriakos, … , Mark J. Miller, Jennifer Alexander-Brett
Published January 28, 2021
Citation Information: JCI Insight. 2021;6(4):e136166. https://doi.org/10.1172/jci.insight.136166.
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Research Article Immunology Pulmonology

Epithelial IL-33 appropriates exosome trafficking for secretion in chronic airway disease

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Abstract

IL-33 is a key mediator of chronic airway disease driven by type 2 immune pathways, yet the nonclassical secretory mechanism for this cytokine remains undefined. We performed a comprehensive analysis in human airway epithelial cells, which revealed that tonic IL-33 secretion is dependent on the ceramide biosynthetic enzyme neutral sphingomyelinase 2 (nSMase2). IL-33 is cosecreted with exosomes by the nSMase2-regulated multivesicular endosome (MVE) pathway as surface-bound cargo. In support of these findings, human chronic obstructive pulmonary disease (COPD) specimens exhibited increased epithelial expression of the abundantly secreted IL33Δ34 isoform and augmented nSMase2 expression compared with non-COPD specimens. Using an Alternaria-induced airway disease model, we found that the nSMase2 inhibitor GW4869 abrogated both IL-33 and exosome secretion as well as downstream inflammatory pathways. This work elucidates a potentially novel aspect of IL-33 biology that may be targeted for therapeutic benefit in chronic airway diseases driven by type 2 inflammation.

Authors

Ella Katz-Kiriakos, Deborah F. Steinberg, Colin E. Kluender, Omar A. Osorio, Catie Newsom-Stewart, Arjun Baronia, Derek E. Byers, Michael J. Holtzman, Dawn Katafiasz, Kristina L. Bailey, Steven L. Brody, Mark J. Miller, Jennifer Alexander-Brett

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Figure 6

Analysis of IL-33 and exosomes from COPD bronchial wash specimens.

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Analysis of IL-33 and exosomes from COPD bronchial wash specimens.
(A) E...
(A) ELISA quantified IL-33 in concentrated bronchial wash (BW) fluid (100 kDa filter cutoff) with retention of endogenous IL-33 above the filter. (B) IL-33 and protein concentration measured in fractions eluted from the size-exclusion column (Izon qEV). (C and D) Extracellular vesicles isolated from BW were consistent with exosomes based on transmission electron microscopy (TEM), tunable resistive pulse sensing (TRPS), and dynamic light scattering (DLS). Scale bar: 100 nm. (E) Western blot with CD9+ and EpCAM+ exosome fractions, indicating an epithelial source. (F) Western blot (CTD antibody) showing elution of truncated IL-33 protein (MW approximately 28 kDa), similar to that shown in Figure 4E. See the IL-33 CTD fragment for reference. (G) ELISA analysis of qEV fractions subject to further resolution with Superose6 (Sup6) size exclusion chromatography. Elution profile with peak IL-33 in fraction 17 corresponds to MW = 25 kDa based on protein standard curve. (H and I) HMC1.2 activation assay for purified endogenous BW IL-33 protein. Input IL-33 concentration for purified protein and CTD standard verified by ELISA due to low BW IL-33 yield. IL-8 level in cell supernatant measured by ELISA after 12 hours of incubation with CTD standard, concentrator flow through (FT, negative control), or endogenous IL-33 with or without IL-1RL1 blocking antibody (100 ng/ml, Proteintech). Data are shown as the mean ± SEM. Statistical analysis: 1-way ANOVA (I); ***P < 0.001.

Copyright © 2022 American Society for Clinical Investigation
ISSN 2379-3708

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