Expression of IL‐8 by cells of the odontoblast layer in vitro

Abstract

Due to their peripheral location in the dental pulp and their cellular extension into dentin, odontoblasts are the first pulpal cells to encounter dental pathogens. The association of odontoblasts with immunoglobulins and dendritic cells during microbial invasion of dentin implies that these cells may possess a role in the innate and adaptive pulpal immune responses, however this has not been examined. A pivotal step in the innate immune response is the detection of foreign antigen and the recruitment of immune effector cells to the area. IL-8 is a potent chemotactic cytokine that plays an important role in the inflammatory response. The purpose of this study was to determine if odontoblasts are capable of expressing the pro-inflammatory chemokine IL-8. Human odontoblasts from intact, noncarious third molars were maintained in culture and exposed to Escherichia coli lipopolysaccharide (LPS) (serotype 055:B5) on day 4 for 8-10 h in a humidified 5% CO2 incubator. Control and experimental samples were assayed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot for the production of IL-8 mRNA and protein. Analysis of the PCR products revealed that cells of the odontoblast layer maintained in this culture model constitutively expressed low levels of IL-8, which were increased in response to E. coli LPS exposure. Western blotting confirmed that the mRNA was translated into protein. These results imply that odontoblasts are capable of producing of pro-inflammatory mediators, thereby actively participating in the recruitment of neutrophils in response to bacterial by-products.

TGF-β1 Inhibits TLR-mediated Odontoblast Responses to Oral Bacteria

“…Odontoblasts, the first cells to be exposed to bacteria within the tooth, monitor the invasion of these microbes using TLRs to mount innate host defenses. Previous findings in cultured tooth crown odontoblasts (Levin et al, 1999;Veerayutthwilai et al, 2007) and odontoblast-like cells (Botero et al, 2006;Durand et al, 2006) support these results. In addition, our findings suggest that human odontoblasts are highly responsive to the Gram-negative bacteria, P. intermedia and F. nucleatum.…”

Toll-like receptor 2 activation by lipoteichoic acid induces differential production of pro-inflammatory cytokines in human odontoblasts, dental pulp fibroblasts and immature dendritic cells

“…TNF-a, IL-1b and CXCL8 are normally absent or produced at an extremely low level in healthy tissues due to their potentially deleterious effects on tissue integrity. They are not or barely expressed in healthy human pulps but are up-regulated in inflamed pulps under caries lesions (D'Souza et al, 1989;Huang et al, 1999;Levin et al, 1999;Nakanishi et al, 2001;Pezelj-Ribaric et al, 2002;Zehnder et al, 2003;Kokkas et al, 2007;Pääkkönen et al, 2007;Veerayutthwilai et al, 2007;Farges et al, 2008). In inflamed pulp, cell origin of TNF-a is unknown, but IL-1b was shown to be produced by macrophages and CXCL8 by macrophages, lymphocytes, endothelial cells and odontoblasts (D'Souza et al, 1989;Huang et al, 1999;Nakanishi et al, 2001).…”

Pulp capping materials exert an effect on the secretion of IL-1β and IL-8 by migrating human neutrophils

“…Among the inflammatory cytokines, IL-8 and IL-1β have already been found in the dental pulp. [10][11][12][13][14][15][16][17] In fact, IL8, whose production is generally induced by bacteria, is one of the most important chemotactic cytokines. This cytokine is responsible for recruiting neutrophils, a process required to induce acute inflammation, and is also involved in determining the duration of the inflammatory process.…”