Jieduquyuziyin prescription alleviates lupus development via inhibiting neddylation pathway to promote Bim-induced apoptosis of double negative T cells

Ethnopharmacological relevance: Jieduquyuziyin prescription (JP) is an empirical prescription approved for application to treat systemic lupus erythematosus (SLE) in hospital within China. Despite the prominent treatment effect of JP clinically, further investigation is imperative to explore its underlying mechanisms. Aim of the study: We aim to investigate the impact of JP on DN T cell apoptosis in the treatment of SLE and the specific regulation mechanisms. Materials and methods: Firstly, female MRL/lpr mice were treated with JP and the therapeutic efficacy of JP was evaluated via skin lesions, lymphoid organ enlargement, accumulation of autoantibodies and renal function. Then, flow cytometer analysis was performed to evaluate the proportions and the apoptosis of T cell subpopulations. Based on the above results, double-negative (DN) T cells were subjected to proteomic with subsequent differential screening. The expression of Ube2m and Bim was further validated using real-time PCR and Western blot. Subsequently, DN T cells were incubated with JP-contained serum in vitro, and cell apoptosis was quantified using flow cytometry. Additionally, the expression levels of Ube2m, Bim and other associated proteins were also assessed through western blotting. To further clarify whether Ube2m serves as the key target of JP in regulating DN T cell apoptosis, the mice that Ube2m was specific deleted in T cells with spontaneous lupus (Ube2m- /- lpr) were utilized. JP was administered to WTlpr or Ube2m- /- lpr mice, followed by assessment of the lupus condition and DN T cell apoptosis. Results: JP administration effectively ameliorated the lupus phenotype. Then flow cytometry assay showed that JP treatment enhanced DN T cell apoptosis to reduce their accumulation and restored the immune homeostasis. Proteomic analysis revealed a significant inhibition of Ube2m for JP treatment, which is essential for maintaining homeostasis of DN T cells. Further experiments confirmed that JP treatment effectively downregulated the expression of Ube2m and subsequently upregulated the level of pro-apoptotic protein Bim with decreased Bim degradation. In vitro experiments also confirmed that JP-contained serum significantly facilitated DN T cell apoptosis and reduced DN T cell accumulation by inhibiting Ube2m expression. Furthermore, Ube2m- /- lpr mice were utilized and the impact of JP treatment on the apoptosis of DN T cells was found to be minimal in the absence of Ube2m. Mechanistic investigation reveals that JP exerts its effects by suppressing the expression of Ube2m, subsequently inhibiting CRL-dependent degradation of Bim, and ultimately promoting Bim-induced apoptosis in DN T cells. Furthermore, the blockade of Ube2m in T cells effectively prevents JP-induced apoptosis in DN T cells, underscoring Ube2m as one crucial therapeutic target of JP in mediating DN T cell apoptosis and managing SLE. Conclusions: Our findings indicate that JP treatment effectively restores the homeostasis of DN T cells in SLE by inhibiting Ube2m expression, thereby reducing Bim ubiquitination degradation. This ultimately enhanced DN T cell apoptosis and alleviated lupus phenotype.