Active Ingredient Irigenin from Belamcanda chinensis (L.) DC Alleviates IL-18-Mediated Pyroptosis of Corneal Epithelial Cells in Dry Eye Disease

Abstract

Background: Dry eye disease (DED) is closely coupled with ocular surface inflammation. Irigenin, an active ingredient in traditional Chinese medicine Belamcanda chinensis (L.) DC, possesses various pharmacological effects including anti-inflammation. This study aims to reveal the impact of irigenin on DED. Methods: DED model cells in vitro were constructed by 24-h hyperosmolarity intervention (90 mM sodium chloride (NaCl)) and treated with different concentrations (10, 20 and 40 μM) of irigenin in the same time. Cell counting kit-8, 5-ethynyl-2′-deoxyuridine, Transwell, enzyme-linked immunosorbent assays, and flow cytometry, were used to determine the effect and mechanism of irigenin on DED. The expressions of pyroptosis-related proteins were measured by Western blot. Hyaluronan synthase 2 (HAS2) and HAS3 expressions were quantified by quantitative reverse transcription polymerase chain reaction. Results: Irigenin exerted no cytotoxicity on HCE-2 cells at concentrations of 10, 20 or 40 μM. Irigenin enhanced the viability, proliferation, migration, and inhibited the apoptosis of hyperosmolarity-induced HCE-2 cells, but these effects were reversed by interleukin 18 (IL-18) overexpression. Irigenin decreased the level of IL-1β, tumor necrosis factor alpha (TNF-α) as well as the expressions of Gasdermin-D (GSDMD), IL-18 and caspase-1, but increased the expressions of HAS2 and HAS3 in hyperosmolarity-induced HCE-2 cells. These effects of irigenin on inhibiting inflammation and pyroptosis as well as on promoting hyaluronic acid synthesis in hyperosmolarity-induced HCE-2 cells were reversed by IL-18 overexpression. Conclusion: Irigenin protected HCE-2 cells against hyperosmolarity-induced inflammation and dysfunction by reducing IL-18-mediated pyroptosis. Irigenin has potential in developing therapeutic agents for DED.