Functional effects of LPS and estrogen in the periodontium

Abstract

Objectives: Several studies have addressed the association between changes in the female sex hormones estrogen levels and changes in parameters of periodontitis. Estrogen affects inflammatory conditions in different parts of the body, such as brain, cardiovascular system and in colon. The effects of LPS in PDL cell inflammatory versus normal physiological conditions are poorly mapped. The aim of the present study was to investigate how LPS affects PDL cell inflammatory versus normal physiological characteristics, and if the effect of LPS was reversed by estrogen. Methods: Human PDL cells were obtained from teeth extracted for orthodontic reasons. The cells were cultured from periodontal tissue explants and used in passages 3-5. The cells were treated with different concentrations of Escherichia coli LPS in the absence or presence of estrogen. Cytokine (IL-6 and CRP) and chemokine (MCP-1) production was measured using ELISA. DNA and collagen synthesis was determined by measuring the incorporation of [3H]thymidine and [3H]proline, respectively. ALP activity was determined colorimetrically. All measurements were normalized to total amount of protein. Results and Conclusions: LPS enhanced the inflammatory characteristics of PDL cells, reflected by enhanced production of IL-6 and MCP-1 but did not effect CRP production. LPS had no effect on collagen and DNA synthesis and alkaline phosphatase activity, however, which suggests that LPS does not affect the physiological properties of PDL cells. Estrogen did not reverse LPS-induced IL-6 and MCP-1 production. The present study suggests that PDL cells in response to LPS via enhanced MCP-1 production contribute to the recruitment of leucocytes to the area of inflammation in periodontitis