Localization of P. gingivalis in preterm delivery placenta

Abstract

Increasing evidence suggests an association between periodontal disease and adverse pregnancy outcomes. Although infection is considered as a risk factor for preterm delivery, the localization of oral bacteria or their antigens in chorioamnionitis placental tissue has never been demonstrated. This study was devised to test the hypothesis that periodontal pathogens may be present and affect human placenta in cases of chorioamnionitis. Using immunocytochemistry, we have identified the presence of Porphyromonas gingivalis antigens in placental tissues. The antigens were detected in the placental syncytiotrophoblasts, chorionic trophoblasts, decidual cells, and amniotic epithelial cells, as well as the vascular cells. There was a substantial increase in immunostaining intensity of the tissues sectioned from women with chorioamnionitis compared to those experiencing normalterm pregnancy, p < 0.019 (Mann-Whitney test). These results suggest that P. gingivalis may commonly colonize placental tissue, and that the presence of the organism may contribute to preterm delivery.

Figure 1.

Immunohistochemical localization of P. gingivalis in human placenta (A, and higher magnification in B) and fetal membrane (C) from women with chorioamnionitis. Bacteria are labeled with polyclonal antibodies to P. gingivalis and appear red-brown after immuno-enzymatic color development. Note the presence of immunoreactive P. gingivalis in placental syncytio-trophoblasts (ST) and placental arterial endothelial cells (EC), as well as in amniotic epithelial cells (AM), chorion (CH), and decidual cells (DC). The lowest arrow in (C) shows the presence of a focal inflammatory response with a large inflammatory cell infiltrate, some of which also immunostained for P. gingivalis. (D) Pre-immune rabbit serum as a control did not show any red-brown-staining bacteria. Magnifications: A, C, and D, 60X; B, 150X.

Figure 2.

Immunohistochemical localization of P. gingivalis from women with chorioamnionitis (A,B). Normal placenta (C) and control section (D). Bacteria are labeled with polyclonal antibodies to P. gingivalis and appear red-brown after immuno-enzymatic color development. (D) Pre-immune rabbit serum as a control did not show any red-brown-staining bacteria. Magnifications: 150X.

Figure 3.

Comparison between P. gingivalis expression in placental tissues affected by chorioamnionitis (n = 9), and normal placenta (n = 5). The overall score = intensity × extensiveness. Adapted after Patel et al., 2008. The error bars represent SD.