Immunohistochemical Analysis of S100 Proteins in Normal and Irreversibly Inflamed Human Dental Pulps.

INTRODUCTION: S100 proteins convey important roles in innate immune responses to infection and regenerative processes. However, their role in inflammatory or regenerative processes of the human dental pulp is poorly elucidated. The aim of the present study was to detect, localize, and compare the occurrence of 8 S100 proteins in normal, symptomatic, and asymptomatic irreversibly inflamed dental pulp specimens. METHODS: Human dental pulp specimens from 45 individuals were clinically assigned to 3 groups of pulpal diagnosis: normal pulp (NP, n = 17), asymptomatic irreversible pulpitis (AIP, n = 13), and symptomatic irreversible pulpitis (SIP, n = 15). The specimens were prepared and immunohistochemically stained for proteins S100A1, -A2, -A3, -A4, -A6, -A7, -A8, and -A9. Staining was classified using semiquantitative analysis and a 4-degree staining score (ie, no, decent, medium, and intense staining) at 4 different anatomic or functional regions (ie, the odontoblast layer [OL], pulpal stroma [PS], border area of calcifications [BAC], and vessel walls). The distribution of staining degrees between the 3 diagnostic groups was calculated using the Fisher exact text (P ≤ .05) at the 4 regions. RESULTS: Significant differences in staining were observed mainly in the OL and PS and at the BAC. The most significant differences were detected in the PS and when comparing NP with 1 of the 2 irreversibly inflamed pulpal tissues (AIP or SIP). The inflamed tissues were then invariably stained more intensely than their normal counterparts at this location (S100A1, -A2, -A3, -A4, -A8, and -A9). In the OL, NP tissue was significantly stronger stained for S100A1, -A6, -A8, and -A9 compared with SIP and for S100A9 when compared with AIP. Differences between AIP and SIP in direct comparison were rare and were found only for 1 protein (S100A2) at the BAC. Also, at the vessel walls, only 1 statistical difference in staining was observed (SIP was stronger stained than NP for protein S100A3). CONCLUSIONS: The occurrence of proteins S100A1, -A2, -A3, -A4, -A6, -A8, and -A9 is significantly altered in irreversibly inflamed compared with normal dental pulp tissue at different anatomic localizations. Some members of S100 proteins obviously participate in focal calcification processes and pulp stone formation of the dental pulp.

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

INTRODUCTION: 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. METHODS: Tissue 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. RESULTS: Significantly 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. CONCLUSIONS: The 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.