Bacteria recovered from dental pulp induce apoptosis of lymph node cells

Abstract

Apoptosis is critical in the pathogenesis of several infectious diseases. The induction of apoptosis was assessed in mouse lymph node cells by four bacteria recovered from infected human dental pulp: Gemella morbillorum, Clostridium butyricum, Fusobacterium nucleatum and Bifidobacterium adolescentis. Smaller lymph nodes and smaller numbers of cells were observed after experimental dental pulp infection with C. butyricum, suggesting that this bacterium induces cell death. Apoptosis was evaluated by determination of cell ploidy and detection of DNA degradation in cells cultured with killed bacteria. Paraformaldehyde-killed C. butyricum and heat-killed G. morbillorum induced substantial cell death, while F. nucleatum and B. adolescentis induced cell death at lower levels. No bacterial preparations induced apoptosis in cells from mice genetically deficient for tumour necrosis factor receptor p55 (TNFRp55), implicating this receptor directly or indirectly as a mediator in the process. It was concluded that apoptosis may be induced during periapical lesions of pulpal origin.

Immunological profile of periapical endodontic infections from HIV− and HIV+ patients

“…However, mRNA expression in CD8 + T cells, which are relatively unaffected by HIV infection, was similar to CD4 + T-cell mRNA expression. This may be related to previous findings, which showed that bacteria recovered from human root canal infections are able to induce cellular apoptosis (Ribeiro-Sobrinho et al 2005). Hence, the null hypotheses were partially rejected.…”

“…This may be related to previous findings, which showed that bacteria recovered from human root canal infections are able to induce cellular apoptosis (Ribeiro‐Sobrinho et al . ). Hence, the null hypotheses were partially rejected.…”

T-Lymphocyte and Cytokine Expression in Human Inflammatory Periapical Lesions

“…In this study after the root canal bacterial load was strongly diminished by cleaning and shaping procedures, the mRNA expression of both CD4 + CD28 + and CD8 + T-cell genes statistically increased. This might be justified by previous findings, which showed that bacteria recovered from human root canal infections are able to induce cell apoptosis by TNF receptor p55 (TNFRp55) (14). Hence, in the presence of an active infection, less T cells would survive.…”

Cytokine expression in response to root canal infection in gnotobiotic mice

“…Several studies have used gnotobiotic animals, which permit the evaluation of a specific microbial challenge as a model to study root canal infections (Kakehashi et al. 1965, Ribeiro Sobrinho et al . 2005, 2002).…”