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Determination of the role of P. gingivalis and P. intermedia proteases in mono- and synergistic mixed microbial infections in a mouse model of periodontal disease

Final Report Summary - PERIOPAIN (Determination of the role of P. gingivalis and P. intermedia proteases in mono- and synergistic mixed microbial infections in a mouse model of periodontal disease)

Project context and objectives

These anaerobic microorganisms are well equipped with many different virulence factors such as proteolytic enzymes, which we have been studying in vivo during the two last years of the following project.

To determine the role of P. gingivalis and P. intermedia proteases in microbial infections, two different mouse models of periodontal disease were established in our lab.

Bone loss model was used to test the role of P. gingivalis and P. intermedia proteases in mono- and synergistic mixed microbial infections.

Both types of bacteria were able to induce bone loss in Balb/c mice separately.

However, we didn’t find any difference when the mixed microbial infection was performed. We focused than to test the importance of interpain in P.intermedia on bone loss model. We found that, the infection, the generation of Ab, and the bone loss was stronger when infection was performed with wild type P. intermedia.

Moreover, we developed the mouse chamber model, which gave us the possibility to investigate the role of the host response in the bacterial infection. The subcutaneous chamber model has been described before as a model for the host tissue destruction that occurs in periodontitis.

Using the subcutaneous chamber model, we were able to characterise the inflammatory mediator profile at the sites of infection by a periodontal pathogen, P. gingivalis and to compare the different strains of deficient bacteria. We found that peptidylarginine deiminase (PAD), which catalyses the deimination of peptidylarginine residues of various peptides is an important virulence factor of P. gingivalis.

To reveal if P. g. infection might influence collagen induced arthritis (CIA) in DBA/1 mice, chamber model was employed. The results of our in vivo and in vitro investigation reveal that P. g. is able to enhance CIA in DBA/1 mice, and PPAD is an important virulence factor of this bacterium.