The concentrations of high-sensitivity C-reactive protein (hsCRP) have been reported to be higher in periodontitis patients than in controls (Nakajima et al., 2010). PPARγ is a transcription factor which inhibits production of inflammatory cytokines. In a previous study with pregnant Japanese women, we suggested that PPARγPro12Ala polymorphism represents a genetic susceptibility factor for severity of periodontitis (Hirano et al., 2010). In this study, we investigated possible associations between PPARγ polymorphism, periodontitis and serum hsCRP level, and the effect of PPARγ polymorphism on the relationships between periodontitis and hsCRP level among postmenopausal Japanese women.
Methods:
The final sample of this study was composed of 359 postmenopausal Japanese women. As a parameter of periodontitis, probing depth (PD) was measured per tooth. PPARγPro12Ala genotypes were determined by PCR-RFLP. The CRP concentration was measured using a high-sensitive enzyme-linked immunosorbent assay. A woman with serum hsCRP level≥1mg/l was classified into high CRP group, and <1mg/l was considered normal.
Results:
The percentages of PD≥4mm sites were significantly higher in high hsCRP group than in normal hsCRP group (p=0.003). There was no statistically significant difference between PPARγ Ala allele carriers and non-carriers in age, menopausal age, BMI, number of children, prevalence of periodontitis, and periodontal clinical parameters. Serum hsCRP level was positively correlated with PD≥4mm percentage in the PPARγ Ala allele carrier group (p=0.043, r=0.293), but not in the Ala allele non-carriers. Women with both Ala allele and higher percentage of PD≥4mm sites (>median) demonstrated higher hsCRP levels compared to women without Ala allele and Ala allele carriers with lower percentage of PD≥4mm sites (≤median).
Conclusions:
In postmenopausal Japanese women, the PPARγ Pro12Ala polymorphism was not significantly associated with periodontitis or serum CRP level. However, there was a tendency for serum hsCRP level to increase in women with Ala allele and periodontitis.