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The capacity of Porphyromonas gingivalis to multiply under iron-limiting conditions correlates with its pathogenicity
D Grenier1, V Goulet, D Mayrand
1Groupe de Recherche en Ecologie Buccale, Faculté de Médecine Dentaire, Université Laval, Québec, Canada. Daniel.Grenier@greb.ulaval.ca
Abstract:
Isolates of Porphyromonas gingivalis have various abilities to induce infections in an animal model. The hypothesis of this study was that pathogenic strains of P. gingivalis could multiply under iron-limiting conditions, while non-pathogenic strains could not. Three pathogenic strains (W50, W83, and ATCC 49417) grew to a final optical density (660 nm) > 2 in horse serum, while the growth of the 3 non-pathogenic strains (ATCC 33277, LB13D-2, and HW24D-1) was negligible. When an excess of hemin or ferric chloride was added to the serum, significant growth of the non-pathogenic strains occurred. Under iron-limiting conditions, the pathogenic strains of P. gingivalis had a much lower requirement for human iron-loaded transferrin and hemin than the non-pathogenic strains. Proteolytic degradation of transferrin, which may be associated with the release of iron, was not markedly different for pathogenic and non-pathogenic strains. In addition, no relationship could be established between the level of 55Fe uptake from 55Fe-transferrin and the pathogenicity of strains. Our study provided evidence that the ability of P. gingivalis to multiply in vitro under iron-limiting conditions may be correlated with its ability to induce infections in an animal model. Isolates of P. gingivalis possessing a low requirement for iron are likely to have a higher potential for initiating periodontal infections.
Insights
Pathogenic Porphyromonas gingivalis strains multiply in low-iron conditions, unlike non-pathogenic strains. This iron acquisition ability correlates with their potential to cause periodontal infections.
Area of Science:
- Microbiology
- Oral Health
- Infectious Diseases
Background:
- Porphyromonas gingivalis is a key pathogen in periodontal disease.
- The role of iron availability in P. gingivalis pathogenicity is not fully understood.
Purpose of the Study:
- To investigate the relationship between iron-limiting conditions and the pathogenicity of P. gingivalis strains.
- To determine if P. gingivalis strains with low iron requirements are more pathogenic.
Main Methods:
- Culturing pathogenic and non-pathogenic P. gingivalis strains under iron-limiting conditions (horse serum).
- Supplementing cultures with hemin or ferric chloride to assess iron's impact on growth.
- Measuring iron uptake and transferrin degradation by different strains.
Main Results:
- Pathogenic P. gingivalis strains (W50, W83, ATCC 49417) grew significantly in iron-limited serum, while non-pathogenic strains (ATCC 33277, LB13D-2, HW24D-1) showed negligible growth.
- Non-pathogenic strains exhibited significant growth upon addition of hemin or ferric chloride.
- Pathogenic strains demonstrated a lower requirement for iron-loaded transferrin and hemin under iron-limiting conditions.
Conclusions:
- P. gingivalis's ability to multiply in vitro under iron-limiting conditions correlates with its capacity to induce infections.
- Isolates with a low iron requirement possess a higher potential for initiating periodontal infections.
