Lipopolysaccharide from Porphyromonas gingivalis sensitizes capsaicin-sensitive nociceptors - PubMed (original) (raw)

Lipopolysaccharide from Porphyromonas gingivalis sensitizes capsaicin-sensitive nociceptors

Caio Cezar Randi Ferraz et al. J Endod. 2011 Jan.

Abstract

Although odontogenic infections are often accompanied by pain, little is known about the potential mechanisms mediating this effect. In this study we tested the hypothesis that trigeminal nociceptive neurons are directly sensitized by lipopolysaccharide (LPS) isolated from an endodontic pathogen, Porphyromonas gingivalis. In vitro studies conducted with cultures of rat trigeminal neurons demonstrated that pretreatment with LPS produced a significant increase in the capsaicin-evoked release of calcitonin gene-related peptide (CGRP) when compared with vehicle pretreatment, thus showing sensitization of the capsaicin receptor, TRPV1, by LPS. Furthermore, confocal microscopic examination of human tooth pulp samples showed the colocalization of the LPS receptor (toll-like receptor 4, TLR4) with CGRP-containing nerve fibers. Collectively, these results suggest the direct sensitization of nociceptors by LPS at concentrations found in infected canal systems as one mechanism responsible for the pain associated with bacterial infections.

Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

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Figures

Figure 1

Figure 1

Confocal micrograph of the subodontoblastic plexus near a human pulp horn stained for N52/GAP43 (green), TLR4 (red), CGRP (blue) immunoreactivities (A). TLR4 and CGRP immunoreactivities are separately shown in B and C, respectively. A subset of the N52/GAP43 identified nerve fibers show the colocalization of CGRP and TRL4 (D). The white horizontal arrows show representative areas of colocalization. Scale bar is 7.5 µm.

Figure 2

Figure 2

Effect of LPS on Basal CGRP Release. Rat TG neurons were cultured for 7 days, washed and then exposed to either vehicle or LPS derived from P.gingivalis (2 µg/ml) for 15 min prior to collection of media and assay for CGRP by radioimmunoassay. Treatment Data are presented as mean ± SEM percentage of basal release (n = 6 per group; n.s _p_>0.05, one-way ANOVA with Bonferroni’s post hoc test).

Figure 3

Figure 3

Effect of LPS on Capsaicin-Evoked CGRP Release. Cultured TG neurons were exposed to either vehicle or P.gingivalis LPS (2 µg/ml for 15 min) and then exposed to either vehicle/capsaicin (30nM) or LPS/capsaicin for an additional 15 min. Treatment Data are presented as mean ± SEM percentage of basal release (n = 6 per group; **p < 0.01; *** p < 0.001, one-way ANOVA with Bonferroni’s post hoc test).

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References

    1. Sundqvist G, Johansson E, Sjogren U. Prevalence of black-pigmented bacteroides species in root canal infections. J Endod. 1989;15:13–19. - PubMed
    1. Rocas IN, Siqueira JF, Jr, Andrade AFB, Uzeda M. Identification of selected putative oral pathogens in primary root canal infections associated with symptoms. Anaerobe. 2002;8:200–208.
    1. Shah HN, Collins MD. Proposal for reclassification of Bacteroides asaccharolyticus, Bacteroides gingivalis, and Bacteroides endodontalis in a new genus Porphyromonas. Int J Syst Bacteriol. 1988;3:128–131.
    1. Van Winkelhoff AJ, Carlee AW, de Graaff J. Bacteroides endodontalis and other black-pigmented Bacteroides species in odontogenic abscesses. Infect Immun. 1985;49:494–497. - PMC - PubMed
    1. Gomes BP, Pinheiro ET, Gade-Neto CR, Sousa EL, Ferraz CC, Zaia AA, Teixeira FB, Souza-Filho FJ. Microbiological examination of infected dental root canals. Oral Microbiol Immunol. 2004;19:71–76. - PubMed

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