DNA-based adaptive immunity protect host from infection-associated periodontal bone resorption via recognition of Porphyromonas gingivalis virulence component.
BACKGROUND
Porphyromonas gingivalis (Pg) is one of a constellation of oral organisms associated with human chronic periodontitis. While adaptive immunity to periodontal pathogen proteins has been investigated and is an important component of periodontal bone resorption, the effect of periodontal pathogen DNA in eliciting systemic and mucosal antibody and modulating immune responses has not been investigated.


METHODS
Rowett rats were locally injected with whole genomic Pg DNA in alum. Escherichia coli (Ec) genomic DNA, Fusobacterium nucleatum (Fn) genomic DNA, and saline/alum injected rats served as controls. After various time points, serum IgG and salivary IgA antibody to Ec, Fn or Pg were detected by ELISA. Serum and salivary antibody reactions with Pg surface antigens were determined by Western blot analyses and the specific antigen was identified by mass spectrometry. Effects of genomic DNA immunization on Pg bacterial colonization and experimental periodontal bone resorption were also evaluated.


RESULTS
Sera from Pg DNA, Ec DNA and Fn DNA-injected rats did not react with Ec or Fn bacteria. Serum IgG antibody levels to Pg and Pg surface extracts were significantly higher in animals immunized with Pg DNA as compared to the control groups. Rats injected with Pg DNA demonstrated a strong serum IgG and salivary IgA antibody reaction solely to Pg fimbrillin (41kDa), the major protein component of Pg fimbriae. In the Pg DNA-immunized group, the numbers of Pg bacteria in oral cavity and the extent of periodontal bone resorption were significantly reduced after Pg infection.


CONCLUSIONS
This study suggests that infected hosts may select specific genes from whole genomic DNA of the periodontal pathogen for transcription and presentation. The results indicate that the unique gene selected can initiate a host protective immune response to the parent bacterium.
['Han|Xiaozhe|X|', 'LaRosa|Karen B|KB|', 'Kawai|Toshihisa|T|', 'Taubman|Martin A|MA|']
D056704:Adaptive Immunity D016301:Alveolar Bone Loss D000818:Animals D000917:Antibody Formation D001428:Bacterial Vaccines D016866:Bacteroidaceae Infections D004269:DNA, Bacterial D005260:Female D036781:Fimbriae Proteins D010861:Fimbriae, Bacterial D007070:Immunoglobulin A D007074:Immunoglobulin G D009055:Mouth D010518:Periodontitis D016966:Porphyromonas gingivalis D051381:Rats D011919:Rats, Inbred Strains D012463:Saliva D019444:Vaccines, DNA D014774:Virulence
Bone resorption Porphyromonas gingivalis Pg Immune response Escherichia coli Ec Fusobacterium nucleatum Fn ELISA mass spectrometry APCs Bacterial genomic DNA LPS MS Periodontal disease Vaccine antigen presenting cells enzyme-linked immunosorbent assay lipopolysaccharide