Prednisone acetate modulates Th1/Th2 and Th17/Treg cell homeostasis in experimental autoimmune uveitis via orchestrating the Notch signaling pathway

Uveitis is an immune eye disease that can seriously impair vision. Glucocorticoids (GCS) have been extensively used to treat uveitis, though the mechanisms have not been fully elucidated. In this study, we investigated the regulatory effects of prednisone acetate (PA) on the Th1/Th2 and Th17/Treg balance in experimental autoimmune uveitis (EAU) through modulating the Notch signaling pathway. Briefly, Lewis rats were randomly divided into the normal control (NC), EAU, and EAU + PA groups. Rats in EAU and EAU + PA groups were induced EAU, while those in the EAU + PA group were treated with PA. Clinical and histopathological scores were employed to assess the progression of EAU. The expression levels of Notch signaling-related molecules (Notch1, Notch2, Dll3, Dll4, and Rbpj) and Th-associated cytokines (IFN-γ, IL-4, IL-10, and IL-17) were assessed via quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA). In addition, the frequencies of Th1, Th2, Th17 and Treg cells were detected by flow cytometry. These experimental results indicated that activation of the Notch signaling pathway occurred in EAU rats and resulted in a severe imbalance of the Th17/Treg and Th1/Th2 ratios. PA treatment significantly alleviated ocular inflammation, inhibited activation of the Notch signaling pathway, and declined Th1, and Th17 cell differentiation, thereby restoring the Th1/Th2 and Th17/Treg balance. Collectively, PA can positively enhance the systemic immune response and improve the intraocular microenvironmental homeostasis by inhibiting activation of the Notch signaling pathway and by restoring Th1/Th2 and Th17/Treg balance, thus achieving the goal of treating uveitis.