Role of toll like-receptor 2 in inflammatory activity of macrophage infected with a recombinant BCG expressing the C-terminus of merozoite surface protein-1 of Plasmodium falciparum

Objective: To investigate the role of toll-like receptor 2(TLR2) in inflammatory activity of macrophage infected with the recombinant Mycobacterium bovis bacillus Calmette-Guerin(rBCG). Methods: Mouse macrophage cell line J774 A.1 was infected with Mycobacterium bovis bacillus Calmette-Guerin(BCG) and rBCG cultures for 48 h in the presence or absence of 10 μg/mL of TLR2 inhibitor. Untreated macrophages were used as a negative control while lipopolysaccharide-stimulated macrophages were used as a positive control. The ability of the macrophage to engulf the BCG and rBCG in the absence or presence of TLR2 inhibitor was assessed using a phagocytic assay, while the production of inflammatory cytokines and nitric oxide by the infected macrophages was evaluated using ELISA and Griess reagent method, while the expression of the inducible nitric oxide synthase was determined using Western blot analysis. Results: The results showed that blocking TLR2 function reduced the phagocytic activity, nitric oxide production and proinflammatory cytokine secretion such as TNF-α, IL-1β and IL-12 p40 as well as inducible nitric oxide synthase expression in the infected macrophages. These data showed the importance of TLR2 in the activation of macrophages following BCG and r BCG infections. Conclusions: Through exploring the immunological mechanism which underlies the protection conferred by the candidate vaccine, this study will improve our understanding of the vaccine candidate's mechanism to protect the host from malaria infection.