Analysis of Ednra expression in the gingival tissue during pregnancy

Objective: Periodontitis is a group of inflammatory diseases affecting the tissues surrounding and supporting the teeth. Left untreated, periodontitis will progressively cause the loss of the alveolar bone supporting the teeth and eventually dentition. The inflammatory and immune response of the periodontal tissue to the microbial infection is different among individuals and is influenced by genetic factors, metabolic condition, lifestyle and pregnancy. Periodontal disease is prevalent among pregnant women and is associated with complications such as preterm birth and eclamptic pregnancy. Treatment of periodontitis during pregnancy does not improve the pregnancy outcomes, suggesting the presence of a common hormono-dependent underlying mechanism linking their onset. Elevated endothelin-A receptor (Ednra) expression was previously noted in diseased periodontal tissues. Endothelin signaling is involved in inflammation. Analysis of the non-coding sequences of the Ednra gene revealed the presence of putative progesterone response elements. In this project, we analyzed Ednra expression in the gingival tissue of pregnant and progesterone-treated C57BL6 mice to determine if Ednra is involved in the etiology of periodontitis during pregnancy. Methods: Ednra expression was analyzed by real-time PCR from dissected periodontium. Results: Our results indicate that levels of Ednra expression increase during pregnancy. Progesterone treatment of ovariectomized mice partially recapitulates the effects. The low response to progesterone may explain why C57BL6 mice are more resistant to periodontal disease and are due, in part, to the absence of estrogen stimulation. Conclusion: Our results indicate that Ednra may be part of the molecular mechanisms promoting the onset and progression of periodontitis during pregnancy. However, more studies are needed to confirm this function. Supported by NIH/ NIDCR U24 DE16472 (LBR) and T32 DE018380 (YZ), Baylor Oral Health Foundation (GRK) and a Research Development Grant (LBR) from the VP Office for Research & Graduate Studies/ Texas A&M Health Science Center.