An increase in B cell apoptosis by interfering BAFF-BAFF-R interaction with small synthetic molecules

B cell-activating factor (BAFF) transmitted signals through binding to specific BAFF receptors (BAFF-R) to regulate B cell survival and development. We used MTT assay to examine the cytotoxicity of chemicals, flow cytometry analysis to measure BAFF–BAFF-R interactions, and western blotting to detect BAFF protein. Here, we established screening method to find specific compounds to interfere with BAFF–BAFF-R interactions in WIL2-NS B lymphoblast cells. According to screening (imidazol-4-ylcarbonyl)guanidine or (oxazol-4-ylcarbonyl)guanidine derivatives, we selected KR32592, KR32673, KR33232, KR33341 and KR33426 as candidates to interfere with BAFF–BAFF-R interaction. No cytotoxicity was detected by KR32592, KR33232, and KR33426 at the concentration of 5 μM, and by KR32673, and KR33341 at the concentration of 0.5 μM. Cell population with BAFF–BAFF-R interactions was reduced by the pre-incubation of chemicals with human BAFF-murine CD8 (BAFF-muCD8). Cell population with BAFF–BAFF-R interactions was also decreased by pre-exposure of WIL2-NS cells to chemicals prior to the incubation with BAFF-muCD8. Chemicals also inhibited LPS-stimulated BAFF production from splenocytes. All these effects of chemicals may contribute to the inhibition of BAFF-mediated anti-apoptosis. These data demonstrate that chemicals interfering with BAFF–BAFF-R interaction may be screened with our experimental condition. It suggests that BAFF–BAFF-R interaction could be a chemical target to develop therapeutics for BAFF-mediated autoimmune diseases.