Fusobacterium nucleatum induces cytokine production through Toll-like-receptor-independent mechanism
Article first published online: 19 SEP 2013
© 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd
International Endodontic Journal
Volume 47, Issue 6, pages 550–559, June 2014
How to Cite
Fusobacterium nucleatum induces cytokine production through Toll-like-receptor-independent mechanism. International Endodontic Journal, 47, 550–559, 2014., , .
- Issue published online: 10 MAY 2014
- Article first published online: 19 SEP 2013
- Accepted manuscript online: 21 AUG 2013 02:05AM EST
- Manuscript Accepted: 16 AUG 2013
- Manuscript Received: 24 APR 2013
- Ministry of Education Singapore. Grant Number: R222-000-042-133
- bacterial invasion;
- Fusobacterium nucleatum ;
- nucleotide-binding oligomerization domain-1;
- nucleotide-binding oligomerization domain-2;
- p38 mitogen-activated protein kinase;
- Toll-like receptors
To determine whether Fusobacterium nucleatum's ability to invade cells allows the bacteria to activate pro-inflammatory response through cytosolic pattern recognition receptors, independent of surface Toll-like receptors (TLRs).
HEK293T cells, which lack endogenous TLRs, and overexpressing dominant negative myeloid differentiation primary response gene 88 (MyD88DN) protein, were infected with F. nucleatum and the production of interleukin-8 (IL-8) was determined. The necessity for intracellular invasion of the bacteria for cytokine production was also investigated by blocking bacterial invasion with cytochalasin D. The roles of NFĸB and p38 mitogen-activated protein kinase (MAPK) and nucleotide-binding oligomerization domain-1 (NOD-1) signalling pathways in F. nucleatum-induced IL-8 secretion were determined.
Fusobacterium nucleatum-infected HEK293T cells produced IL-8 independent of the MYD88 signalling. This response was inhibited by preventing F. nucleatum invasion into HEK293T cells. p38 MAPK but not the NFĸB signalling pathway was required for F. nucleatum-mediated IL-8 production. HEK293T cells expressed NOD-1 but not NOD-2. Yet, inhibition of NOD-1 signalling did not affect F. nucleatum-induced IL-8 secretion.
Fusobacterium nucleatum invasion led to cytokine production, which is mediated by the p38 MAPK signalling but independent of TLRs, NOD-1, NOD-2 and NFĸB signalling.