TLR5 activation induces expression of the pro-inflammatory mediator Urokinase Plasminogen Activator via NF-κB and MAPK signalling pathways in human dental pulp cells

H-S Hwang; J-W Kim; S-H Oh; J H Song; J-W Yang; Y Zang; Y-H Kim; S-E Lee; Y-C Hwang; J-T Koh

doi:10.1111/iej.13140

TLR5 activation induces expression of the pro-inflammatory mediator Urokinase Plasminogen Activator via NF-κB and MAPK signalling pathways in human dental pulp cells

Int Endod J. 2019 Oct;52(10):1479-1488. doi: 10.1111/iej.13140. Epub 2019 Jun 5.

Authors

H-S Hwang^{1

2}, J-W Kim^{1

2}, S-H Oh^{1

2}, J H Song^{1

2}, J-W Yang^{1

2}, Y Zang^{1

2}, Y-H Kim^{1

2}, S-E Lee¹, Y-C Hwang^{2

3}, J-T Koh^{1

2}

Affiliations

¹ Department of Pharmacology and Dental Therapeutics, Chonnam National University, Gwangju, Korea.
² Research Center for Biomineralization Disorders, Chonnam National University, Gwangju, Korea.
³ Department of Conservative Dentistry, School of Dentistry, Chonnam National University, Gwangju, Korea.

PMID: 31062874
DOI: 10.1111/iej.13140

Abstract

Aim: To explore the involvement of TLR5 in pulp inflammation and to examine the effects of TLR5 activation with its ligand, FlaB protein, on pro-inflammatory gene expression.

Methodology: TLR5 expression in dental pulp tissues and human dental pulp cells (hDPCs) were determined by immunohistochemistry, immunocytochemistry, Western blots and RT-PCR analyses. To examine the role of TLR5, hDPCs were treated with recombinant FlaB protein (500 ng mL^-1 ) to activate the receptor or with a small interfering RNA against TLR5 (si-TLR5) to downregulate the receptor. After exposure to FlaB, the expression of inflammation-related proteins was screened using a protein array kit. Western blots or qRT-PCR analyses were performed to identify changes in the expression of uPA (urokinase plasminogen activator), TIMPs (tissue inhibitor of metalloproteinases), and IL-6 and to determine their signalling pathways. Statistical analysis was performed using one-way analysis of variance (anova) with Tukey post hoc test; P < 0.05 was considered statistically significant.

Result: TLR5 expression was identified in pulp tissues and hDPCs. In the protein array analysis, treatment with FlaB significantly increased uPA expression (P < 0.01) and significantly decreased TIMP1/4 (P < 0.05). FlaB treatment also significantly increased expression of the inflammatory marker IL-6 (P < 0.01). FlaB treatment increased phosphorylation of the NF-κB p65 subunit, JNK, p38 and ERK. Chemical inhibitors of NF-κB (Bay11-7082), p38 (SB202190) or ERK (U0126) decreased the FlaB induction of uPA expression. Downregulation of TLR5 expression by siRNA decreased the FlaB induction of uPA protein and p65 phosphorylation.

Conclusion: TLR5 activation with FlaB treatment induced the expression of uPA via the NF-κB and MAPK signalling pathways. Flagellin-bearing oral bacteria may cause pulp inflammation through TLR5. The findings provide new clues to control pulpal diseases by targeting TLR5 signalling pathways.

Keywords: TLR5; flagellin; human dental pulp cells; pulp inflammation; urokinase plasminogen activator.

MeSH terms

Dental Pulp
Humans
Inflammation Mediators
NF-kappa B*
Plasminogen
Toll-Like Receptor 5
Urokinase-Type Plasminogen Activator*

Substances

Inflammation Mediators
NF-kappa B
Toll-Like Receptor 5
Plasminogen
Urokinase-Type Plasminogen Activator

Abstract

MeSH terms

Substances

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