Altered antigenicity in periodontitis patients and decreased adhesion of Porphyromonas gingivalis by environmental temperature stress

Periodontopathogenic bacteria survive various environmental changes during the progression of periodontal disease. Alterations in metabolism and protein expression will have to take place to adapt their physiological functions to environmental stress. We examined the effects of an elevation of 2°C in temperature on the adhesive ability and antigenicity of Porphyromonas gingivalis. Elevation of growth temperature of P. gingivalis from 37°C to 39°C remarkably suppressed the expression of surface filamentous structures, such as fimbriae, as well as the adhesive capacities to salivary components and Streptococcus oralis. Sera of severe periodontitis patients revealed a marked increase in serological activity with 39°C cells than with 37°C cells. The alteration of protein profiles of bacterial surface components by temperature elevation was demonstrated by SDS-PAGE, and their Western blot profiles were also different from those of cells grown at 37°C. Although a uniform trend was not found in the altered patterns, sera from severe periodontitis patients detected more antigenic proteins in cells grown at 39°C than 37°C cells. These observations suggest that P. gingivalis downregulates the expression of fimbriae and alters its adhesive capacity and antigenicity by the temperature stress that could occur during the disease progression.