Fig. 1

Elevated IL-20 levels in the tears of patients with DED and DED animal model corneas. a–c Tear samples were harvested from non-DED controls (n = 33) and patients with DED (n = 40). Tear IL-20, IL-6, and IL-8 levels were measured using ELISAs. Mann–Whitney test, *p < 0.05 and *** p < 0.001. Data are shown as the mean ± SEM. d Mice were topically administered PBS or BAC twice daily for 4 weeks (for each group, n = 10). Bilateral extra-orbital lacrimal gland excision was applied to induce an aqueous tear-deficient DED animal model for 4 weeks, sham was used for control mice (for each group, n = 10). Mice were housed in a CEC with low humidity for 28 days for DS-induced DED; non-induced mice served as healthy controls (for each group, n = 10). Mice were harvested tear for each week and analyzed for protein level of IL-20 by ELISA. One-way ANOVA, **p < 0.01, ***p < 0.001, and ****p < 0.0001. Data are shown as the mean ± SEM. e Immunohistochemical (IHC) staining was used to detect the protein expression of IL-20 in the mouse cornea. The reaction was detected using staining with the chromogen AEC (red), and the nuclei were counterstained with hematoxylin (blue). Original magnification: ×400. The experiments in e were independently repeated three times, with similar results, and the data of one representative experiment is shown. DED dry eye disease, ELISA enzyme-linked immunosorbent assay, PBS phosphate-buffered saline, BAC benzalkonium chloride, CEC controlled environment chamber, LGE lacrimal gland excision, DS desiccating stress