Apoptosis in Porphyromonas gingivalis–specific T‐cell lines

Abstract

Fluorescence-activated cell sorter analysis and transmission electron microscopy were used to determine the presence of apoptotic cells in Porphyromonas gingivalis-specific T-cell lines established from the peripheral blood of 10 P. gingivalis-infected individuals. P. gingivalis outer membrane antigens were presented to the T cells by autologous Epstein-Barr virus-transformed B cells for 6, 24, 48 and 72 h. Transmission electron microscopy demonstrated the presence of typical apoptotic cells in all cultures. Annexin V-positive cells were present at low concentrations at all 4 four periods. A mean of approximately 2-3% of the CD4 cells and 1-3.5% of the CD8 cells were annexin V-positive, with an increase to around 5.5% positive CD4 cells at 6 h in wells containing P. gingivalis compared with cultures not containing antigen. This difference was not, however, significant at the 0.05 level (P = 0.073). The mean (+/- standard error) CD4:CD8 ratios of the T-cell lines when first established using peripheral blood mononuclear cells as antigen-presenting cells was significantly higher (5.2 +/- 1.1) than when transformed B cells were used as antigen-presenting cell (1.2 +/- 0.5). While this study has shown apoptosis occurring in the T-cell lines, it has not shown definitively that the reversion in the CD4:CD8 ratio in the P. gingivalis-specific T cells following antigen presentation by autologous Epstein-Barr virus-transformed B cells is due to apoptosis of a CD4 population. Alternatively, the reversion in the CD4:CD8 ratio could be due to a selective proliferation of the CD8 population which, in turn, could be relevant to the immunopathology of periodontal disease induced by P. gingivalis.

Genetic variation in the recognition of Porphyromonas gingivalis antigens in mice

“…This and our previous study in which mice were immunized using a dose of 100 μg of P. gingivalis followed by subcutaneous challenge with live organisms (14) have demonstrated that P. gingivalis appears to stimulate CD8 cells to produce cytokines to a greater extent than CD4 cells. We have also shown that P. gingivalis induces apoptosis in CD4 cells rather than CD8 cells and may also lead to an expansion of a CD8 cell population (12). These results suggest that, at least in some strains, P. gingivalis may have an inhibitory effect on T cells, particularly CD4 cells.…”

The Influence of Genetic Variation on the Splenic T Cell Cytokine and Specific Serum Antibody Responses to Porphyromonas gingivalis in Mice

“…The CD4/CD8 ratio in the T cell lines was reduced to well below 1, although whether the apoptosis of the CD4 cells was the sole contributing factor could not be ascertained. 16 However, the significance of the lower CD4/CD8 ratios induced by P. gingivalis in the C57BL6 mice remains to be determined.…”

The chronicles of Porphyromonas gingivalis: the microbium, the human oral epithelium and their interplay

“…P. gingivalis induces apoptosis in Jurkat T-cells, a non-oral epithelial cancer line (KB cells), B cells and human gingival fibroblasts, but inhibits apoptosis in human monocytes, macrophages, neutrophils and primary GECs (Chen et al ., 2001; Geatch et al ., 1999; Gemmell et al ., 1999; Hiroi et al ., 1998; Nakhjiri et al ., 2001; Ozaki & Hanazawa, 2001; Preshaw et al ., 1999; Yilmaz et al ., 2004). On the other hand, a recent in vitro study designed to examine host cell death, utilizing primary GECs and heat-killed P. gingivalis , suggested that the dead organism in elevated numbers could induce apoptosis without any necrosis, by upregulation of the NFκB pathway (Brozovic et al ., 2006).…”