Immunoregulatory gene polymorphisms in Japanese women with preterm births and periodontitis

Many studies have reported an association between periodontal disease and preterm birth, although this remains controversial. Cytokines and antibodies produced to give resistance to infection can enter the bloodstream and cause preterm labor. We analyzed maternal genetic polymorphisms in various immunoregulatory genes that could affect both preterm birth and periodontitis. A total of 1099 women referred to the Department of Obstetrics and Gynecology, Niigata University Medical and Dental Hospital were candidates for participation, 424 of whom refused, and 553 were excluded. The final number of subjects was 122 (51 with preterm birth, 71 with term birth). Genomic DNA was isolated from venous blood, and 22 polymorphisms were determined: IL-1A, IL-1B, IL-1RN, IL-2, IL-4, IL-6, IL-10, TNFA, TNFRI, TNFRII, FcγRIIA, FcγRIIB, FcγRIIIA, FcγRIIIB, and FcαR. Within five days of labor, periodontal parameters were evaluated, and bacteria from subgingival plaque were detected using real-time PCR. There was no difference in the prevalence and degree of periodontitis between term and preterm births. Chi-squared tests showed that an age <33 years and FcαR(+56)T/C alleles were associated with preterm birth. Multiple logistic regression analysis represented a model with significant fitness in which four variables were associated with preterm birth: maternal age, number of Aggregatibacter actinomycetemcomitans, IL-6(-572)G/C, and FcαR(+56)T/C. In conclusion, there was no association between preterm birth and periodontitis in this study. A. actinomycetemcomitans, IL-6, and FcαR were suggested to be associated with preterm birth. Multiple logistic regression models with both genetic and environmental factors would be useful for evaluating susceptibility to preterm birth.