| The cell surface molecule CD40is a member of the tumor necrosis factorreceptor superfamily and is broadly expressed by immune, hematopoietic,vascular, epithelial, and other cells, including a wide range of tumor cells.Many studies have reported that CD40activation by agonist CD40antibody can overcome tumor antigen-specific T-cell tolerance and evokeeffective cytotoxic T-cell response that eradicates lymphoma and bypassT-cell help in vivo. According to these findings, CD40agonists couldrescue the function of antigen-presenting cells in tumor-bearing hosts andtrigger or restore effective immune responses against tumor-associatedantigens. CD40is considered as a potential target for novel cancer therapy.In this study, we designed a strategy different from agonist CD40antibodyand may be useful to create tools to mimic or interfere with CD40-CD40Lpathway. We constructed an oligo-peptide library and used virtualscreening on high performance computers to find peptides targeting tohuman CD40protein. According to the in-silico molecule docking results,six hexapeptides were synthesized and undergone SPR assay to test theiractual biding affinities to CD40. SPR analysis confirmed that onehexapeptide named N9bound rhsCD40immobilized on the CM5chip. Wethen constructed N9peptide-conjugated liposome and tested its bindingaffinity to CD40positive B cells. When changes in the amino acidcomposition were introduced in the sequence of the N9peptide, thebinding to CD40was abrogated, suggesting that the amino acid sequencewas critical for its specificity. Finally, we evaluated the capacity ofN9-liposome to induce maturation of dendritic cells generated frommurine bone marrow cells. The N9-liposomes resulted in the up regulationof costimulatory molecules such as CD80and CD86on DCs to a certain extent.In summary, we designed an in silico peptide screening platform and usedit to discover a CD40L-derived oligo-peptide, which was able to mimic thebinding ability of CD40L to CD40in in vitro assays. The biological effectsrelated to the CD40-CD40L ligation was also evaluated and it was foundthat the peptide could stimulate dendritic cell activation through bindingwith CD40. Our findings could be used for selective disruption oractivation of CD40pathway, and provided the ground for the developmentof new treatments against immunological based diseases andmalignancies. |
