Bacterial species associated with persistent apical periodontitis exert differential effects on osteogenic differentiation

• AimTo determine if bacteria associated with persistent apical periodontitis induce species-specific pro-inflammatory cytokine responses in macrophages, and the effects of this species-specific microenvironment on osteogenic differentiation. MethodologyMacrophages were exposed to Enterococcus faecalis, Streptococcus oralis, Streptococcus mitis, Fusobacterium nucleatum, Treponema denticola or Tannerella forsythia, and levels of TNF- and IL-1 elicited were determined by immunoassay. Following treatment of MG-63 pre-osteoblasts with conditioned media from bacteria-exposed macrophages, osteogenic differentiation and viability of osteoblasts were analyzed by Alizarin Red Staining and MTS assay, respectively. Statistical analysis was carried out by one-way anova with the Tukey post-hoc test. Differences were considered to be significant if P<0.05. ResultsMacrophages exposed to Gram-positive bacteria did not produce significant amounts of cytokines. F.nucleatum-challenged macrophages produced up to four-fold more TNF- and IL-1 compared to T.denticola or T.forsythia. Only conditioned media from macrophages treated with Gram-negative bacteria decreased mineralization and viability of osteoblasts. ConclusionsGram-positive bacteria did not impact osteogenic differentiation and appeared innocuous. Gram-negative bacteria, in particular F.nucleatum elicited an enhanced pro-inflammatory response in macrophages, inhibited osteogenic differentiation and reduced cell viability. The findings suggest that the presence of this organism could potentially increase the severity of persistent apical periodontitis.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Odontologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Dentistry (hsv//eng)

Nyckelord

Fusobacterium nucleatum

inflammation

macrophages

osteoblasts

persistent apical periodontitis

necrosis-factor-alpha

canal-treated teeth

alkaline-phosphatase

activity

root-filled teeth

bone-formation

deoxyribonucleic-acid

periapical lesions

collagen-synthesis

interleukin-1-beta

osteoblast

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