Alpha hemolysin boosts immune response by modulating the differentiation of dendritic cells

Alpha hemolysin, a pore-forming toxin from Staphylococcus aureus, is considered to be an important virulence factor and vaccine candidate for the bacteria. Previous studies have shown that the Hla mutant H35A, acting as a carrier protein, significantly enhances immune protection against various bacterial and viral antigens. However, the specific mechanism underlying this effect is not fully elucidated. In this study, we investigated the impact of HlaH35A on different dendritic cell populations through the ADAM10 receptor when used as an antigen carrier. Our results demonstrate that fusion of HlaH35A improves antigen uptake by interacting with ADAM10 on dendritic cells (DCs), thereby enhancing their antigen-presenting capacity. Furthermore, the interaction between HlaH35A and ADAM10 activates Notch signaling, leading to the differentiation of conventional DCs (cDCs) into Notch2-dependent cDC2s. Using a DCs transfer mouse model, we found that HlaH35A-induced cDCs promote type 3 immune responses, resulting in the differentiation of Th17 and Tfh cells and enhancing antigen-specific antibody titers and protective efficacy. Togenther, our findings suggest that HlaH35A enhances immune protection by modulating DCs differentiation through the ADAM10-Notch signaling, independent of pattern recognition receptors (PRRs). These results highlight the importance of HlaH35A as a novel intramolecular adjuvant in antigen design.