Mycobacterium bovis BCG Producing Interleukin-18 Increases Antigen-Specific Gamma Interferon Production in Mice

AUTOR(ES)

Biet, Franck

FONTE

American Society for Microbiology

RESUMO

Interleukin-18 (IL-18) and IL-12 play a critical role in the expression of cell-mediated immunity involved in host defense against intracellular pathogens. Both cytokines are produced by macrophages and act in synergy to induce gamma interferon (IFN-γ) production by T, B, and natural killer cells. In the present study, we analyzed both cellular and humoral responses upon infection with IL-18-secreting BCG of BALB/c and C3H/HeJ mice, two strains known to differ in their ability to support the growth of BCG. The cDNA encoding mature IL-18 was fused in frame with the alpha-antigen signal peptide-coding sequence, cloned downstream of the mycobacterial hsp60 promoter and expressed in BCG. IL-18 produced by the recombinant BCG strain was functional, as judged by NF-κB-mediated luciferase induction in a tissue culture assay. When susceptible mice were infected with IL-18-producing BCG, their splenocytes were found to produce higher amounts of Th1 cytokines after stimulation with mycobacterial antigens than the splenocytes of mice infected with the nonrecombinant BCG. This was most prominent for IFN-γ, although the mycobacterial antigen-specific secretion of granulocyte-macrophage colony-stimulating factor and IL-10 was also augmented after infection with the recombinant BCG compared to infection with nonrecombinant BCG. In contrast, the immunoglobulin G levels in serum against mycobacterial antigens were lower when the mice were infected with IL-18-producing BCG compared to infection with nonrecombinant BCG. The IL-18 effect was delayed in BALB/c compared to C3H/HeJ mice. These results indicate that the production of IL-18 by recombinant BCG may enhance the immunomodulatory properties of BCG further toward a Th1 profile. This may be particularly useful for immunotherapeutic or prophylactic interventions in which a Th1 response is most desirable.

Documentos Relacionados

• Specific bovine brucellosis diagnosis based on in vitro antigen-specific gamma interferon production.
• Recombinant Mycobacterium bovis BCG secreting functional interleukin-2 enhances gamma interferon production by splenocytes.
• Control of Leishmania infantum Infection Is Associated with CD8+ and Gamma Interferon- and Interleukin-5-Producing CD4+ Antigen-Specific T Cells
• Antigen provoking gamma interferon production in response to Mycobacterium bovis BCG and functional difference in T-cell responses to this antigen between viable and killed BCG-immunized mice.
• Autoimmunity to heat shock protein 60 and antigen-specific production of interleukin-10.