Interleukin-6 -174 genotype, periodontal disease and adverse pregnancy outcomes: a pilot study

Periodontal Pathogens and Adverse Pregnancy Outcomes: A Narrative Review

Periodontal disease is a multi-microbial infection of the teeth-supporting apparatus that manifests as clinical attachment loss and alveolar bone loss. The association between periodontal disease and systemic diseases has been proposed in the literature owing to the former's chronic state of inflammation, and adverse pregnancy outcomes are no exception. As a result of periodontal pathogen invasion, a series of systemic inflammatory and immunologic events affecting the safety of the fetoplacental unit may unfold. This may be further exaggerated by physiologic hormonal and metabolic fluctuations during pregnancy. This can not only negatively affect the gestation period and consequently cause preterm low weight but also complicate the pregnancy via preeclampsia and gestational diabetes. This narrative review article aims to provide a summary of relevant available evidence pertinent to the relationship between periodontal diseases, associated periodontal pathogens and virulence mechanisms mediated by pro-inflammatory cytokines and prostaglandins, and adverse pregnancy outcomes. Furthermore, this article highlights some of the literature addressing the impact of periodontal therapy interventions and pregnancy outcomes.

Ancestry informative markers and selected single nucleotide polymorphisms in immunoregulatory genes on preterm labor and preterm premature rupture of membranes: a case control study

Background

A genetic predisposition to Preterm Labor (PTL) and Preterm Premature Rupture of Membranes (PPROM) has been suggested; however the relevance of polymorphisms and ancestry to susceptibility to PTL and PPROM in different populations remains unclear. The aim of this study was to evaluate the contribution of maternal and fetal SNPs in the IL1B, IL6, IL6R, TNFA, TNFR, IL10, TLR2, TLR4, MMP9, TIMP1 and TIMP2 genes and the influence of ancestry background in the susceptibility to PTL or PPROM in Brazilian women.

Methods

Case–control study conducted at a tertiary hospital in São Paulo State, Brazil. We included women with PTL or PPROM and their babies (PTL: 136 women and 88 babies; PPROM: 65 women and 44 babies). Control group included 402 mother-babies pairs of term deliveries. Oral swabs were collected for identification of AIMs by fragment analysis and SNPs by Taqman® SNP Genotyping Assays and PCR. Linkage Disequilibrium and Hardy-Weinberg proportions were evaluated using Genepop 3.4. Haplotypes were inferred using the PHASE algorithm. Allele, genotype and haplotype frequencies were compared by Fisher’s exact test or χ² and Odds Ratio. Logistic regression was performed. Clinical and sociodemographic data were analyzed by Fisher’s exact test and Mann–Whitney.

Results

PTL was associated with European ancestry and smoking while African ancestry was protective. The fetal alleles IL10-592C (rs800872) and IL10-819C (rs1800871) were also associated with PTL and the maternal haplotype TNFA-308G-238A was protective. Maternal presence of IL10-1082G (rs1800896) and TLR2A (rs4696480) alleles increased the risk for PPROM while TNFA-238A (rs361525) was protective. Family history of PTL/PPROM was higher in cases, and time to delivery was influenced by IL1B-31T (rs1143627) and TLR4-299G (rs4986790).

Conclusion

There is an association between European ancestry and smoking and PTL in our Brazilian population sample. The presence of maternal or fetal alleles that modify the inflammatory response increase the susceptibility to PTL and PPROM. The family history of PTL/PPROM reinforces a role for genetic polymorphisms in susceptibility to these outcomes.

Relationship between periodontal diseases and preterm birth: recent epidemiological and biological data

For ten years, the incidence of preterm birth does not decrease in developed countries despite the promotion of public health programs. Many risk factors have been identified including ethnicity, age, tobacco, and infection. However, almost 50% of preterm birth causes remain unknown. The periodontal diseases are highly prevalent inflammatory and infectious diseases of tooth supporting tissues leading to an oral disability. They influence negatively general health worsening cardiovascular diseases and diabetes. Periodontal diseases have been also suspected to increase the rate of preterm birth, but data remain contradictory. The objective of this review is to present the principal results of epidemiological, biological, and interventional studies on the link between periodontal diseases and preterm birth. The conclusions of this work underline the importance for the physician/obstetrician to identify women at risk for preterm birth and to address these patients to dentist for periodontal examination and treatment in order to limit adverse pregnancy outcomes.

Periodontal diseases as an emerging potential risk factor for adverse pregnancy outcomes: A review of concepts

Preterm birth is the leading perinatal problem with subsequent morbidity and mortality in developed as well as developing nations. Among the various possible environmental, genetic, demographic, psychosocial and obstetric risk factors responsible for premature labor, poor oral health with periodontal infection has also emerged as a potential and modifiable risk factor for preterm low birth weight babies. The infected periodontium is regarded as a reservoir for periodontopathic bacteria, mainly gram negative anaerobes that serve as a source of endotoxins and lipopolysaccharides, proinflammatory cytokines and prostaglandins that enhance uterine muscle contraction leading to preterm low birth weight. Also, the progression of periodontal disease during pregnancy appears to increase the fetal growth restriction, irrespective of baseline periodontal disease status. Thus, identification and treatment of periodontal disease should be considered an important intervention strategy as a part of prenatal care to reduce adverse pregnancy outcomes.

Peroxisome proliferator-activated receptor gamma polymorphism and periodontitis in pregnant Japanese women

BACKGROUND

Recent studies suggest an association between maternal periodontitis and preterm birth, although the association remains controversial. It was suggested that mechanisms such as a genetic predisposition for a hyperinflammatory response cause periodontitis and preterm births. Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear hormone receptor and ligand-dependent transcription factor. PPARgamma inhibits the transcriptional activity of the genes that produce proinflammatory mediators and repress periodontitis. Recently, a common polymorphism, proline(PRO)-to-alanine(ALA) mutation at codon12 in exonB (Pro12Ala: rs 1801282) PPARgamma, was reported to reduce the ability to transactivate responsive promoters. In this study, we tested whether the PPARgammaPro12Ala polymorphism was associated with maternal periodontitis and/or preterm birth.

METHODS

Genomic DNA was isolated from the venous blood of pregnant Japanese women (term birth: n = 72; preterm birth: n = 58). The PPARgammaPro12Ala genotype was determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism. Within 5 days after labor, clinical periodontal parameters were evaluated, and periodontopathic bacteria from the subgingival plaque were detected by species-specific PCR.

RESULTS

The mean clinical attachment level (P = 0.012), mean probing depth (P = 0.031), mean gingival index (P = 0.037), and percentages of sites with bleeding on probing (P = 0.041) in women with the PPARgammaPro12Ala genotype were significantly higher than in women with the PPARgammaPro12Pro genotype. However, there was no association between preterm birth and periodontitis.

CONCLUSION

We suggest that the PPARgammaPro12Ala polymorphism may represent a genetic susceptibility factor for the clinical measurements of periodontitis in a limited number of pregnant Japanese women, but it probably cannot influence the relationship between periodontitis and preterm birth.

A critical assessment of adverse pregnancy outcome and periodontal disease

BACKGROUND

Pre-term birth is a major cause of infant mortality and morbidity that has considerable societal, medical, and economic costs. The rate of pre-term birth appears to be increasing world-wide and efforts to prevent or reduce its prevalence have been largely unsuccessful.

AIM

To review the literature for studies investigating periodontal disease as a possible risk factor for pre-term birth and adverse pregnancy outcomes.

MAIN FINDINGS AND CONCLUSION

Variability among studies in definitions of periodontal disease and adverse pregnancy outcomes as well as widespread inadequate control for confounding factors and possible effect modification make it difficult to base meaningful conclusions on published data. However, while there are indications of an association between periodontal disease and increased risk of adverse pregnancy outcome in some populations, there is no conclusive evidence that treating periodontal disease improves birth outcome. Based on a critical qualitative review, available evidence from clinical trials indicates that, although non-surgical mechanical periodontal treatment in the second trimester of pregnancy is safe and effective in reducing signs of maternal periodontal disease, it does not reduce the rate of pre-term birth. Clinical trials currently underway will further clarify the potential role of periodontal therapy in preventing adverse birth outcomes. Regardless of the outcomes of these trials, it is recommended that large, prospective cohort studies be conducted to assess risk for adverse pregnancy outcome in populations with periodontal disease. It is critical that periodontal exposure and adverse birth outcomes be clearly defined and the many potential confounding factors and possible effect modifiers for adverse pregnancy outcome be controlled in these studies. If periodontal disease is associated with higher risk of adverse pregnancy outcome in these specific populations, large multicenter randomized-controlled trials will be needed to determine if prevention or treatment of periodontal disease, perhaps combined with other interventions, has an effect on adverse pregnancy outcome in these women.