Gene Expression Analysis of Chronically Inflamed and Healthy Human Periodontal Ligament Cells in vivo

Abstract

Background: In the periodontium, the functions of the cell populations regarding the host-mediated tissue destruction in health and disease are not well understood. The purpose of this study was to measure the expression of genes differentially expressed in chronically inflamed periodontal ligament (PDL) cells compared to healthy PDL cells.

Methods: We compared the genome-wide gene expressions of chronically inflamed and healthy PDL cells by microarray analysis, and validated the data by real-time RT-PCR to identify the genes that might play distinct roles in chronic periodontal disease in vivo.

Results: The expression rates of 14,239 genes were investigated and 3,165 of them were found differentially expressed by at least two-fold; the expression rates of 1,515 genes were significantly upregulated and the expression rates of 1,650 genes were significantly downregulated in inflamed PDL cells.

Conclusion: We focused on mainly structural components, for example, laminins and integrins, as well as degrading enzymes, for example, MMPs and cathepsins. The molecular composition of the laminin network varies in chronically inflamed compared to healthy PDL cells in vivo. Furthermore, integrin alpha6beta4, together with laminin-332, might be involved in chronic periodontal inflammation. Diverse keratins were upregulated, indicating that the epithelial cell rests of Malassez might also be involved in chronic periodontitis. The microarray analysis has identified a profile of genes potentially involved in chronic periodontal inflammation in vivo.

Keywords: Extracellular matrix, inflammation, microarray analysis, periodontal ligament