TLR9/NF-kB Pathway Regulates Brucella CpG DNA-mediated Cytokine Response in Human Peripheral Blood Mononuclear Cells

It was reported that targeting the Toll-like receptor9(TLR9) signaling pathway can be a promising therapeuticstrategy forinterventions in various inflammatory and infectiousdiseases. However,it was not known whether the human TLR9 isresponsive to Brucellacytidine-phosphate-guanosine (CpG) DNAsequences and activatesthehost’s innate immune system. The present study aimed to identify the novel humanTLR9agonists from Brucella CpG oligodeoxynucleotide(ODN) candidatesand verify their immune response regulatorymechanisms. Molecular docking methods were used to discover potentagonists of the human TLR9. The potential molecules were furthervalidated by Western blot and enzyme-linked immunosorbentassay(ELISA). The experiment results showed a strong interactionandgood compatibility between the human TLR9 and BrucellaODN-1molecule. In addition, the induction of immune response byBrucella ODN-1 is a CpG-specific response. Moreover, the effectsof Brucella ODN-1 on cytokine response are dependent on theTLR9-mediated NF-κB pathway. These results indicated that the Brucella ODN-1 molecule canserve as a starting point to discover or designmore potent and specific TLR9 agonists that have the potential usein the treatment of infectious diseases.