Enterococcus faecalis promotes osteoclast differentiation within an osteoblast/osteoclast co-culture system.
OBJECTIVE
To investigate the effects of heat-killed Enterococcus faecalis ATCC 29212 and P25RC clinical strain (derived from an obturated root canal with apical periodontitis) on osteoclast differentiation within an osteoblast/osteoclast co-culture system.


RESULTS
Heat-killed E. faecalis significantly increased the proportion of multinucleated osteoclastic cells (MNCs) within the co-culture system. The IL-6 level was significantly increased upon exposure to heat-killed E. faecalis. Gene expression levels of NFATc1 and cathepsin K were significantly up-regulated compared to the untreated control. EphrinB2 and EphB4 expressions at both the mRNA and protein levels were also significantly upregulated compared to the untreated control.


CONCLUSIONS
Heat-killed E. faecalis can induce osteoclast differentiation within the osteoblast/osteoclast co-culture system in vitro, possibly through ephrinB2-EphB4 bidirectional signaling.
Endodontics, Comprehensive Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, 999077, China.|Shenzhen ENT Institute, Shenzhen Longgang ENT Hospital, Shenzhen, 518172, Guangdong, China.
Zuhui
Z
Deng
Endodontics, Comprehensive Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, 999077, China.
Shuai
S
Wang
Endodontics, Comprehensive Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, 999077, China.
Boon Chin
BC
Heng
Endodontics, Comprehensive Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, 999077, China.
Changyong
C
Yuan
Endodontics, Comprehensive Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, 999077, China. zhangcf@hku.hk.
Chengfei
C
Zhang
D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D018920:Coculture Techniques; D013293:Enterococcus faecalis / Q000472:pathogenicity*; D004797:Enzyme-Linked Immunosorbent Assay; D051379:Mice; D010006:Osteoblasts / Q000382:microbiology*; D010010:Osteoclasts / Q000382:microbiology*; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
Enterococcus faecalis; EphB4; EphrinB2; Multinucleated osteoclastic cells; Osteoblasts; Osteoclast differentiation; Osteoclasts