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. 2023 Sep 12;229(5):1419–1429. doi: 10.1093/infdis/jiad383

Figure 1.

Figure 1.

IL-13 treatment increases the abundance of DPP4 in human airway epithelia. A (left), Well-differentiated air-liquid interface cultures of primary HAE were maintained for 3 days in medium containing IL-17A/TNF-α (20 ng/mL; 10 ng/mL), IL-1α (20 ng/mL), or PBS. After 3 days, ELISA was used to determine DPP4 protein abundance in cell lysates (n = 6 HAE donors). Data are presented as mean ± SE. A (right), HAE were stimulated for 3 days with PBS or IFN-γ (100 ng/mL), and DPP4 protein in cell lysates was quantified by ELISA (n = 4). B, HAE were stimulated for 3 days with PBS, IFN-λ (1 ng/mL), or IL-13 (10 ng/mL), and DPP4 protein was measured in cell lysates (n = 7). A and B, A ratio paired t test was used to test for statistically significant differences in cytokine-treated epithelia relative to the PBS control. *P < .05. ns = not significant. C (left), HAE (n = 4) were grown in medium containing IL-13 at the indicated concentrations for 3 days; then, ELISA was used to determine DPP4 protein abundance in cell lysates. Repeated measures 1-way analysis of variance, followed by a Dunnett multiple-comparison test, was used to test for significant differences between IL-13 treatment at each concentration and baseline (0 ng/mL). *P < .05. C (right), HAE (n = 3) were stimulated with IL-13 (20 ng/mL) for 3 days; then, IL-13 was removed from the growth medium and the epithelia maintained for an additional 6 days. DPP4 abundance in cell lysates was measured by ELISA. A ratio paired t test was used to test for significant differences between time points. *P < .05. D, HAE (n = 4) were treated for 3 days with IL-13 (20 ng/mL) or PBS, followed by flow cytometry to quantify DPP4+ cells. Percentages of DPP4+ cells are plotted for each HAE donor. A ratio paired t test was used to test for a statistically significant difference between the PBS and IL-13 conditions. **P < .01. DPP4, dipeptidyl peptidase 4; ELISA, enzyme-linked immunosorbent assay; HAE, human airway epithelia; IFN-γ, interferon γ; IFN-λ, interferon λ; IL-1­α, interleukin 1­α; IL-13, interleukin 13; IL-17A, interleukin 17A; ns, not significant; PBS, phosphate-buffered saline; TNF-α, tumor necrosis factor α.