Oral immunization with Porphyromonas gingivalis outer membrane protein and CpGoligodeoxynucleotides elicits T helper 1 and 2 cytokines for enhanced protective immunity.

The aim of this study was to evaluate the efficacy of an oral vaccine containing the 40-kDa outer membrane protein of Porphyromonas gingivalis (40K OMP) and synthetic oligodeoxynucleotides containing unmethylated CpG dinucleotides (CpG ODN) to control oral infection by P. gingivalis. [run on]40K-OMP40K-OMP40K-OMPOral immunization with 40K-OMP plus CpG ODN induced significant 40K-OMP-specific serum IgG, IgA and saliva IgA antibody responses. The 40K-OMP-specific CD4(+) T cells induced by oral 40K-OMP plus CpG ODN produced both Th1 (IFN-gamma) and Th2 (IL-4) cytokines. Furthermore, increased frequencies of CD11c(+)B220(+) DCs and CD11c(+)CD11b(+) DCs with up-regulated expression of CD80, CD86, CD40 and MHC II molecules were noted in spleen, Peyer's patches and cervical lymph nodes. Immunized mice were then infected orally with P. gingivalis to determine whether the immune responses induced by oral 40K-OMP plus CpG ODN were capable of suppressing bone resorption caused by P. gingivalis infection. Mice given 40K-OMP plus CpG ODN showed significantly reduced bone loss associated with oral infection by P. gingivalis.Thus, oral administration of 40K-OMP together with CpG ODN induces Th1- and Th2-type cells, which provide help for protective immunity against P. gingivalis infection. This may be an important tool for prevention of chronic periodontitis.