Objective: To investigate the expression of lipopolysaccharides (LPS) receptors CD14 and TLR4 in normal and inflamed human dental pulp tissue and fibroblasts and to determine the signal transduction pathway of LPS in pulpitis.
Methods: CD14 and TLR4 expression in healthy and inflammatory pulps was observed by immunohistochemistry. The rates of CD14 and TLR4 positive cells and the mean fluorescence intensity in in vitro cultured pulp fibroblasts before and after being stimulated by LPS.
Results: CD14 and TLR4 were not detected in healthy pulp tissues, but they were strongly positively stained in inflammatory pulps. Ratio of TLR4 positive cells and mean fluorescence intensity produced by the cells stimulated by LPS increased significantly compared with normal pulp cells. However, there were no CD14 expression in human dental pulp cells before and after LPS stimulation.
Conclusions: This study revealed a significant increase in the expression of CD14 and TLR4 in inflamed human dental pulp tissue. Human dental pulp cells could be induced by LPS to express TLR4, which may play an important role in the process of pulpitis.