Figure 3.

Long-term exposure to IL-13 increases DPP4 abundance and induces goblet cell metaplasia in human airway epithelia. A, Representative images from HAE treated for 21 days with PBS or IL-13. dPAS staining was performed to confirm increased mucin production and goblet cell frequency. Scale bar: 20 µm. B, DPP4 protein abundance was measured by ELISA in cell lysates from HAE treated with PBS or IL-13 (20 ng/mL) for 21 days (n = 13). Data points represent individual HAE donors. C, Flow cytometry was used to quantitate total percentages of DPP4-expressing cells after a 21-day treatment with PBS or IL-13 (n = 9). B and C, A ratio paired t test was used to test for statistically significant differences between IL-13– and PBS-treated epithelia. ****P < .0001. D, Representative images from HAE treated for 21 days with vehicle (PBS) or IL-13. Immunofluorescent staining for the goblet cell marker MUC5AC was used to confirm goblet cell metaplasia in the IL-13–treated cells, with increased DPP4. Scale bars: 20 µm. E, Single-cell RNA-sequencing data show normalized gene expression levels for DPP4 in basal, ciliated, goblet, and secretory cell populations in HAE treated with IL-13 for 2 or 21 days. Cell type identifications were made with canonical cell–type markers. Bas, basal cells; Cil, ciliated cells; Gob, goblet cells; Sec, secretory cells. F, Orthogonal z-stack images from HAE treated for 21 days with PBS or IL-13. Epithelia were stained for DPP4 and nuclei with DAPI. Scale bars: 20 µm. dPAS, diastase and periodic acid–Schiff; DPP4, dipeptidyl peptidase 4; ELISA, enzyme-linked immunosorbent assay; HAE, human airway epithelia; IL-13, interleukin 13; PBS, phosphate-buffered saline.