Expression profiling of S100-proteins in healthy and irreversibly inflamed human dental pulps

AIM

Several S100 proteins have been shown to play an important role in the innate immune response to infection and in regenerative processes. However, they have scarcely been investigated during inflammation of the dental pulp. Therefore, in this study we performed gene expression profiling of S100 proteins in healthy and inflamed human dental pulps.

METHODOLOGY

Tissue samples of human dental pulps were used including fifteen clinically diagnosed as symptomatic irreversible pulpitis (SIP), seven as asymptomatic irreversible pulpitis (AIP), and nineteen as healthy pulp (HP). S100 gene expression levels were quantitatively evaluated for S100 A1, A2, A3, A4, A6, A7, A8, A9, A10, A11, A13, A14, and A16 by qPCR technique. In order to monitor the status of inflammation and degradation of pulp tissues, IL-8, COX-2, and HMGB-1 gene expression was also analysed, with GAPDH serving as reference gene. Differential expression rates for each target gene between SIP, AIP, and HP were evaluated by analysis of variance (ANOVA) followed by Bonferroni post-hoc-test.

RESULTS

Significantly reduced gene expression levels could be detected in SIP compared to HP for S100A1, A2, A3, A4, A6, A10, A13, and for HMGB-1, while gene expression of S100A8, A14, and IL-8 were significantly increased. In AIP, significantly increased expression levels compared to HP were only detected for S100A14, A16, and for IL-8, with other genes of interest not being altered.

CONCLUSIONS

The present study revealed significant differences in gene expression profiles of S100 proteins comparing samples from healthy and inflamed dental pulps. More pronounced differences were observed for symptomatic than for asymptomatic pulpitis.

The ability of selected oral microorganisms to emit red fluorescence

Some novel caries detection and excavation devices rely on the ability of bacteria to produce red fluorescing compounds. The aim of this study was to examine the ability of selected oral microorganisms to emit red fluorescence. Streptococcus mutans, S. oralis, S. salivarius, S. sobrinus, Lactobacillus fermentans, L. casei, L. rhamnosus, Actinomyces naeslundi, A. israelii, Prevotella intermedia, and Fusobacterium nucleatum were inoculated onto Columbia agar with haemin and vitamin K and incubated anaerobically for up to 7 days in the dark. The resulting bacterial colonies were excited using filtered xenon light (405 +/- 20 nm) and digitally photographed through a 530-nm high-pass filter. The red and green portions of the colony fluorescence were analyzed using a computer program and the red/green ratio was calculated. All colonies emitted both red and green fluorescence. The green outweighed the red portion for the following species (in descending order) S. oralis, S. salivarius, S. mutans, F. nucleatum and S. sobrinus. The red portion was higher for the following species (in descending order) P. intermedia, A. naeslundi, A. israelii, L. fermentans, L. rhamnosus and L. casei. With all the bacteria examined, one color portion generally outweighed the other, giving the visual impression of either red or green fluorescence. We conclude that red fluorescence is well suited to detection of the bacteria which cause dentin caries but it is not suitable as an indicator of the presence and activity of the streptococci involved in initial caries.