B cell function in patients with systemic lupus erythematosus is regulated by the upregulation of JunD

Purpose: Systemic lupus erythematosus (SLE) is largely caused by B cell dysfunction. JunD is an activator protein 1 family protein that has been linked to the regulation of apoptotic and proliferative activities. However, the precise mechanism(s) by which JunD functions remains to be fully elucidated. Accordingly, this study aimed to clarify the functional importance of JUND gene expression in SLE, with further analyses of the functional role that JunD plays as a regulator of B cell proliferation and immune function. Methods: Reverse transcriptase quantitative polymerase chain reaction techniques were used to analyze JunD expression in B cells of patients with SLE and healthy subjects. Cell Counting Kit-8 (CCK-8) assays and flow cytometry methods were used to characterise proliferative activity, cell cycle progression, and apoptosis of B cells in which JunD was either knocked down or overexpressed. The immune status and autophagic activity of these cells were assessed using Western immunoblotting and enzyme-linked immunosorbent assay (ELISA). Additionally, a JunD knockdown mouse model was established, and the functional role of B cell JunD expression in the pathogenesis of SLE was assessed using Western immunoblotting, ELISA, and haematoxylin and eosin staining. Results: B cells from patients with SLE exhibited upregulation of JunD, with overexpression facilitating in vitro cellular proliferation and modulation of the immune and autophagic status of these B cells. JunD knockdown was also sufficient to modulate in vivo immune function and the autophagic status of B cells. Conclusion: JunD was upregulated in the B cells of patients with SLE, where it regulates proliferation, autophagy, and immunity.