Development of a Novel Aspiration Pneumonia Mouse Model Using Porphyromonas gingivalis

Abstract

Porphyromonas gingivalis (P. gingivalis), an important periodontal pathogen, has been reported to be involved in aspiration-induced pneumonia. Its virulence factors involve FimA and Mfa1 fimbriae, with diverse gene variants across strains, showing potential associations with pathogenicity. In this study, we aimed to develop a novel aspiration pneumonia mouse model by infecting the lungs with two different fimbrial genotypes of P. gingivalis strains ATCC 33277 and 1439 via the oral route, addressing the limitations of existing methods. The survival rate seven days post-infection was examined in a non-invasively induced aspiration pneumonia mouse model. P. gingivalis bacterial colony counts in lung tissue and serological and anatomical observations of the acute-phase inflammatory response after 24 h were performed. Results showed that the survival rate of mice infected with the 1439 strain was lower than that of mice infected with ATCC 33277. The number of P. gingivalis colonies was higher in the 1439 strain than in the ATCC 33277 strain. Inflammatory cytokines in alveolar lavage fluid significantly increased following P. gingivalis infection, and TNF-α production was significantly higher in mice infected with the 1439 strain. The air content in lung tissue was lower in the P. gingivalis infection group than in the control group. In conclusion, while the 1439 strain evaded the immune host response, the host developed severe acute pneumonia with elevated TNF-α levels and increased mortality. This study demonstrates the strain-dependent virulence of P. gingivalis in the novel pneumonia model and highlights the need for detailed studies on the factors that influence its pathogenesis.