Lipopolysaccharide-binding Protein Inhibits Toll-like Receptor 2 Activation by Lipoteichoic Acid in Human Odontoblast-like Cells

• Published in: Journal of endodontics Vol. 39; no. 8; pp. 1008 - 1014
• Main Authors: Carrouel, Florence, PhD, Staquet, Marie-Jeanne, PhD, Keller, Jean-François, DDS, PhD, Baudouin, Caroline, PhD, Msika, Philippe, PhD, Bleicher, Françoise, PhD, Alliot-Licht, Brigitte, DDS, PhD, Farges, Jean-Christophe, DDS, PhD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2013; Elsevier
• Subjects: Acute-Phase Proteins - pharmacology; Carrier Proteins - pharmacology; CD14; Cell Culture Techniques; Computer Science; CXCL8; Dentistry; Endocrinology & Metabolism; Extracellular Signal-Regulated MAP Kinases - drug effects; Gram-Positive Bacteria - immunology; human dental pulp; Humans; IL-6; innate immunity; Interleukin-6 - analysis; Interleukin-8 - analysis; LBP; Life Sciences; Lipopolysaccharide Receptors - pharmacology; Lipopolysaccharides - pharmacology; MAP Kinase Kinase 4 - drug effects; MAP Kinase Signaling System - drug effects; Membrane Glycoproteins - pharmacology; NF-kappa B - drug effects; NF-κB; Odontoblasts - drug effects; Odontoblasts - immunology; p38; p38 Mitogen-Activated Protein Kinases - drug effects; pathogen-associated molecular pattern; Pulpitis - immunology; Ribosomal Protein S6 Kinases, 70-kDa - drug effects; STAT3 Transcription Factor - drug effects; Teichoic Acids - pharmacology; Toll-like receptor; Toll-Like Receptor 2 - antagonists & inhibitors; Toll-Like Receptor 2 - drug effects; NF-κB; CXCL8; innate immunity; p38; human dental pulp; CD14; LBP; pathogen-associated molecular pattern; IL-6; Toll-like receptor
• ISSN: 0099-2399; 1878-3554
• DOI: 10.1016/j.joen.2013.04.020

Abstract Introduction Previous studies have suggested that odontoblasts sense gram-positive bacteria components through Toll-like receptor 2 (TLR2) and trigger dental pulp immunity by producing proinflammatory cytokines. Currently, the factors that modulate odontoblast TLR2 activation are unknown. Our aim was to investigate lipopolysaccharide-binding protein (LBP) effects on the TLR2-mediated odontoblast response. Methods Human odontoblast-like cells were stimulated with lipoteichoic acid (LTA) (a TLR2 ligand), LBP, CD14 (a TLR2 cofactor), or various combinations of LTA/LBP, LTA/CD14, or LTA/CD14/LBP. CXCL8, IL6, and TLR2 gene expression was assessed by real-time polymerase chain reaction. CXCL8 and interleukin (IL)-6 production was determined by enzyme-linked immunosorbent assay in culture supernatants of cells stimulated with LTA, LTA/CD14, or LTA/CD14/LBP. LBP effects on nuclear factor kappa B (NF-κB), p38, JNK, ERK, STAT3, and p70S6 signaling pathways were determined in LTA-stimulated odontoblast-like cells with a multiplex biometric immunoassay. LBP effects were compared with specific inhibitors of these signaling pathways. LBP transcript and protein were investigated in vivo in healthy and inflamed dental pulps by real-time polymerase chain reaction and immunohistochemistry. Results Activation of CXCL8, IL6, and TLR2 gene expression and CXCL8 and IL-6 secretion in LTA- and LTA/CD14-stimulated odontoblast-like cells was significantly decreased by LBP. LBP inhibited NF-κB and p38 signaling pathways in LTA-stimulated cells in a similar way to NF-κB and p38 inhibitors. LBP transcript and protein were detected in vivo in inflamed dental pulps but not in healthy ones. Conclusions These results demonstrate that LBP reduces TLR2-dependent production of inflammatory cytokines by odontoblast-like cells. We suggest that in this way it could modulate host defense in human dental pulp.