Endogenous neddylation in B cells regulates immune responses in mice

ObjectiveNeddylation is an important post-translational modification involved in various physiological and pathological processes, but its regulatory role in B cell-mediated immune responses remains unclear. B cells exhibit different response to thymus dependent antigens and thymus independent antigens, making it significant to explore the role of neddylation in this process.MethodsB cell-specific Ube2m knockout mice CD19cre/+Ube2mfl/fl were constructed using the Cre-LoxP system, with littermate Ube2mfl/fl (Ctrl) mice as controls. Mice were immunized with 4 antigens (thymus dependent antigens: NP-CGG and DNP-KLH, thymus independent antigens: NP-LPS and DNP-Ficoll), respectively. Serum levels of NP/DNP specific antibodies (IgM, IgG1, IgG2a, IgG2b, IgG2c, IgG3) were detected by ELISA, and the proportions of germinal center B cells and plasma cells in the spleen and bone marrow were analyzed by flow cytometry. Statistical analysis was used to evaluate the differences in immune responses.ResultsCompared with the Ctrl mice, CD19cre/+Ube2mfl/fl mice showed significantly reduced levels of NP/DNP specific IgG1、IgG2a、IgG2b、IgG2c、IgG3 after thymus independent antigens (NP-LPS, DNP-Ficoll) immunization, while IgM levels were mostly unchanged, and the reduced proportions of plasma cells and germinal center B cells in the bone marrow or spleen were observed. In thymus dependent antigens (NP-CGG, DNP-KLH) immunization models, CD19cre/+Ube2mfl/fl mice exhibited significantly decreased levels of IgM, IgG1, IgG2a, IgG2b, IgG2c, IgG3, with differences in the timing and magnitude of antibody reduction induced by different antigens. A significant reduction in the proportions of plasma cells and NP specific germinal center B cells in the spleen were also observed.ConclusionsDeficiency of B cell-intrinsic neddylation extensively impairs immune responses to both thymus independent antigens and thymus dependent antigens in mice, including early primary immune responses, Th1-type cellular immune responses, and Th2-type humoral immune responses, with antigen-dependent regulatory effects. This study provides experimental evidence for understanding the role of neddylation in B cell mediated immune responses.