Immunostimulatory activity of recombinant Mycobacterium bovis BCG that secretes major membrane protein II of Mycobacterium leprae.
We previously demonstrated that major membrane protein II (MMP-II) is one of the immunodominant antigens (Ags) of Mycobacterium leprae capable of activating T cells through Toll-like receptor 2. Based on the observation that Mycobacterium bovis BCG secreting a 30-kDa protein offered better protection against tuberculosis, we constructed a recombinant BCG strain (BCG-SM) that secretes MMP-II to improve the potency of BCG against leprosy. The secreted MMP-II protein from BCG-SM stimulated monocyte-derived dendritic cells (DC) to produce interleukin-12. DC infected with BCG-SM expressed MMP-II on their surfaces, and MMP-II expression was suppressed by the pretreatment of DC with chloroquine. These results indicated that secreted MMP-II was processed by DC for higher expression levels on their surfaces. In addition, BCG-SM phenotypically activated DC and induced higher expression levels of major histocompatibility complex, CD86, and CD83 Ags on DC than did vector control BCG (BCG-pMV). The DC infected with BCG-SM more efficiently stimulated naïve and memory CD4+ T cells and memory CD8+ T cells to produce gamma interferon than did those infected with BCG-pMV. However, naïve CD8+ T cells were significantly activated only when they were stimulated with BCG-SM-infected DC. When CD8+ T cells were cocultured with BCG-SM-infected DC, the proportion of perforin-producing T cells was significantly higher than that in cells cocultured with BCG-pMV-infected DC. Moreover, MMP-II-specific memory T cells were more efficiently produced in mice inoculated with BCG-SM than in mice inoculated with BCG-pMV. Taken together, these results indicate that BCG capable of secreting the immunodominant Ag is more potent in the stimulation of T cells.
Makino
Masahiko
M
Department of Microbiology, Leprosy Research Center, National Institute of Infectious Diseases, 4-2-1 Aobacho, Higashimurayama, Tokyo 189-0002, Japan. mmaki@nih.go.jp
Maeda
Yumi
Y
Inagaki
Katsuya
K
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D018920:Coculture Techniques; D005818:Genetic Engineering; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009163:Mycobacterium bovis / Q000235:genetics* / Q000276:immunology*; D009166:Mycobacterium leprae / Q000235:genetics* / Q000276:immunology; D014376:Tuberculosis / Q000276:immunology / Q000662:veterinary
D001426:Bacterial Proteins; D008565:Membrane Proteins; C500901:major membrane protein II, Mycobacterium leprae