DNA-based adaptive immunity protect host from infection-associated periodontal bone resorption via recognition of Porphyromonas gingivalis virulence component

Abstract

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 (41kD), 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.

Comparison of Experimental Diabetic Periodontitis Induced byPorphyromonas gingivalisin Mice

“…The selection of bacteria with different virulence is important in making sure of the alveolar bone loss [26]. P. gingivalis W50 is more aggressive in experimental mice for severe periodontal tissue damage because of its high virulence, compared to other strains such as P. gingivalis 381 and W83 [27, 28]. This research implied that P. gingivalis W50 could cause significant periodontal tissue destruction and alveolar bone loss in all infected mice, indicating that oral infection of W50 is an available method to establish periodontitis mice models with both types 1 and 2 diabetes.…”

Antibody Titer Against Porphyromonas Gingivalis in Rats with Experimentally Induced Periodontitis

“…Four-week-old rats in groups 1-3 were vaccinated with 0.2 mL of the suspension via a subcutaneous injection at the back of their neck. All groups were vaccinated again with the same dose two weeks after the first vaccination (booster) [3,4,6]. One week after booster injection, rats were anesthetized with ether and blood was drawn from their retrobulbar vascular network using a capillary tube.…”

“…This modality is costly and unfavorable for patients and has a variable prognosis [3]. At present, P. gingivalis is known as the main periopathogenic microorganism responsible for occurrence of chronic periodontitis [4][5][6]. It is a rod-shaped, asaccaharolytic, non-mobile, anaerobic Gramnegative microorganism from the family of black pigmented microorganisms, which can stimulate the humoral immune response via its several virulence factors including lipopolysaccharides, cysteine proteases known as gingipains, fimbria, extracellular DNA and severe invasion to tissues [1][2][3]7].…”

“…In mammals, vaccination with killed whole cells of P. gingivalis significantly decreases the progression of periodontitis caused by the oral microflora such as infection with P. gingivalis [3]. Moreover, in vaccination with whole cells of P. gingivalis, reduction in bone loss has been reported in rats with periodontitis [3][4][5][6]8]. Sharma et al [8] used fimbria of P. gingivalis for vaccination of rats and noticed relative immunization (60%) against periodontitis induced by P. gingivalis.…”

“…Findings of animal studies support the use of P. gingivalis vaccine as an adjunct for treatment of chronic periodontitis in humans. Accordingly, we selected P. gingivalis since it can stimulate the humoral immune response in hosts via several virulence factors such as outer membrane vesicles containing virulence factors such as LPS and gingipains, arginine, lysine cysteine proteases and fimbria [3,4,10]. We used the formalin killed whole cell (FKWC) P. gingivalis for vaccination of rats to assess its role in achieving acquired active immunity as a preliminary step for use of such vaccines for human periodontitis.…”