Expression Profiling of S100 Proteins in Healthy and Irreversibly Inflamed Human Dental Pulps

Abstract

IntroductionSeveral 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. MethodsTissue samples of human dental pulps were used, including 15 clinically diagnosed as symptomatic irreversible pulpitis (SIP), 7 as asymptomatic irreversible pulpitis (AIP), and 19 as healthy pulp (HP). S100 gene expression levels were quantitatively evaluated for S100A1, -A2, -A3, -A4, -A6, -A7, -A8, -A9, -A10, -A11, -A13, -A14, and -A16 by the quantitative polymerase chain reaction 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 analyzed with GAPDH serving as the reference gene. Differential expression rates for each target gene between SIP, AIP, and HP were evaluated by analysis of variance followed by the Bonferroni post hoc test. ResultsSignificantly reduced gene expression levels could be detected in SIP compared with HP for S100A1, -A2, -A3, -A4, -A6, -A10, and -A13 and for HMGB-1, whereas the gene expression of S100A8 and -A14 and IL-8 were significantly increased. In AIP, significantly increased expression levels compared with HP were only detected for S100A14 and -A16 and IL-8, with other genes of interest not being altered. ConclusionsThe present study revealed significant differences in gene expression profiles of S100 proteins comparing samples from healthy and inflamed dental pulp. More pronounced differences were observed for symptomatic than for asymptomatic pulpitis.