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A1296 - HSP90 Inhibition Reverts IL13- and IL17-Induced Goblet Cell Metaplasia in Human Airway Epithelia
Author Block: A. Pezzulo, R. A. Tudas, C. G. Stewart, P. J. Taft, N. D. Gansemer, D. A. Stoltz, J. Zabner; Internal Medicine, University of Iowa, Iowa City, IA, United States.
Introduction: Goblet cell metaplasia (GCM) and mucus hypersecretion contribute to significant morbidity in cystic fibrosis, asthma, allergic rhinitis, chronic bronchitis and post-infectious bronchitis. Some treatments are available for mucus hypersecretion in Type 2-high (i.e. IL13-driven) asthma; in contrast, few options exist for the Type 2-low asthma endotype, of which IL17 is a potential driver. Therefore, there is a critical unmet need for therapies for Type 2-low asthma. We have previously shown that HSP90 inhibition prevents IL13-induced GCM in cultured human airway epithelia (HAE). We hypothesized that HSP90 inhibition would revert both IL13- and IL17-induced GCM in HAE, and that the cellular mechanism is: A) induction of goblet cell death, B) transdifferentiation of goblet cells to another cell type, or C) inhibition of mucin synthesis.
Methods and Results: We exposed HAE cultures to IL13 or IL17 for 3 weeks to induce GCM. Immunohistochemistry for the mucin MUC5AC and other cell type markers showed an increase in goblet cells and a matching decrease in ciliated cells. We then added an HSP90 inhibitor for 2 weeks. HSP90 inhibition reverted both IL13- and IL17-induced GCM and increased the number of ciliated cells. To determine if inhibition of HSP90 induces goblet cell death in the HAE cultures, we performed membrane viability stains and apoptosis assays. We found that HSP90 inhibition did not induce cell death in HAE cultures. To determine whether HSP90 inhibition induces transitional goblet-ciliated cells suggestive of transdifferentiation, we performed transmission electron microscopy of goblet cell-rich cultures exposed to HSP90 inhibitors. We were unable to find any transitional goblet-ciliated cells. Finally, to determine whether HSP90 inhibition blocks mucin synthesis, we performed immunofluorescence staining of mucin secretion machinery components. We found that, while MUC5AC levels almost disappeared after HSP90 inhibition, many cells continued to express components of the mucin secretion machinery.
Conclusions: We conclude that HSP90 inhibition can revert IL13-induced GCM; but more importantly, it can also revert IL17-induced GCM. IL17-induced GCM may be a driver of Type 2-low asthma, for which there are very few therapeutic options. Our data also suggests that HSP90 inhibition does not induce goblet cell death and may instead block mucin synthesis independent of the initial GCM trigger. HSP90 may be an important therapeutic target to control mucus hypersecretion in a broad range of pulmonary diseases.