Brucella Outer Membrane Proteins to Control Maturation and Antigen Presentation of Mouse Dendritic Cells

Background: Brucellosis is a highly contagious zoonotic disease, which seriously endangers animal husbandry in China. Bone marrow- derived dendritic cells ( DCs ) are professional antigen presenting cells (APC) that play an important role in the interaction between pathogens and host immunity. Because of that DCs play an irreplaceable role in the initiation and orientation of the acquired immune response, establishing the model of interaction between Brucella and DCs may be more suitable than the traditional macrophage model for understanding the relationship between the pathogenic mechanism of Brucella and the specific immune response of the infected host. In this study, DCs were isolated from BALB/C female mice and stimulated with Brucella major outer membrane proteins (OMPs: OMP10, OMP19, OMP25, BP26 and OMP31) or brucella mutants (Δ omp10 , Δ omp19 , Δ omp25 , Δ bp26 , Δ omp31 ) to examine their effects on DC maturity and antigen presentation. Results: : Brucella OMP10, OMP19, BP26, brucella mutants Δ omp10 , Δ omp19 , Δ omp25 , Δ bp26 , Δ omp31 and Brucella RB51 induced DC maturation and antigen presentation efficiency in mice, activated proliferation of T lymphocytes, and decreased apoptosis, which helped the host recognize antigens and eliminate pathogens. However, Brucella 2308 evaded the host immune function and established chronic infection by maintaining a balance between intracellular replication and inducing apoptosis, thus reducing DC maturation and antigen presentation to T cells. Toll-like receptor (TLR) -mediated signaling pathways were involved in the DC maturation and antigen presentation induced by Brucella OMPs. Conclusion: These results enhance understanding of Brucella pathogenesis and the host protective immune response mechanism and lay the foundation for the rational design of Brucella vaccines.