Subgingival Microbiome in Pregnancy and a Potential Relationship to Early Term Birth

Interleukin 1 beta and its association with the periodontal health of pregnant women

Objectives

In this study, we measured and compared serum and gingival crevicular fluid (GCF) levels of interleukin 1 beta (IL-1β) in pregnant women with periodontitis and pregnant women with a healthy periodontium. We also determined the prevalence of periodontitis among pregnant women attending Omdurman Midwifery Hospital.

Materials

This was a hospital-based clinical study and laboratory investigation using ELISA tests of 80 pregnant women in the third trimester conducted at the Omdurman Midwifery Hospital in Khartoum, Sudan. The study group consisted of 50 women while the control group consisted of 30 women.

Results

Independent samples t-tests were used to compare serum and GCF levels of IL-1β between the study and control groups. Pearson's correlation analysis was also used to compare gingival parameters and IL-1β levels in the GCF. For each comparison, the p-value was fixed at 0.05. The GCF in the research group showed a considerable increase in IL-1β levels. There was also a strong positive association between high IL-1β levels in the research group's GCF and probing pocket depth (PPD) and clinical attachment level (CAL) levels.

Conclusions

Our study provides further evidence that periodontitis, as measured by a PD ≥4 mm and a CAL ≥3 mm, is associated with an increased level of IL-1β in the GCF of pregnant women with active periodontal disease during pregnancy and may include the transient translocation of oral organisms to the utero-placental unit, inciting placental inflammation or oxidative stress early in pregnancy, ultimately resulting in placental damage and clinical manifestations.

Predicting preterm birth using machine learning techniques in oral microbiome

Preterm birth prediction is essential for improving neonatal outcomes. While many machine learning techniques have been applied to predict preterm birth using health records, inflammatory markers, and vaginal microbiome data, the role of prenatal oral microbiome remains unclear. This study aimed to compare oral microbiome compositions between a preterm and a full-term birth group, identify oral microbiome associated with preterm birth, and develop a preterm birth prediction model using machine learning of oral microbiome compositions. Participants included singleton pregnant women admitted to Jeonbuk National University Hospital between 2019 and 2021. Subjects were divided into a preterm and a full-term birth group based on pregnancy outcomes. Oral microbiome samples were collected using mouthwash within 24 h before delivery and 16S ribosomal RNA sequencing was performed to analyze taxonomy. Differentially abundant taxa were identified using DESeq2. A random forest classifier was applied to predict preterm birth based on the oral microbiome. A total of 59 women participated in this study, with 30 in the preterm birth group and 29 in the full-term birth group. There was no significant difference in maternal clinical characteristics between the preterm and the full-birth group. Twenty-five differentially abundant taxa were identified, including 22 full-term birth-enriched taxa and 3 preterm birth-enriched taxa. The random forest classifier achieved high balanced accuracies (0.765 ± 0.071) using the 9 most important taxa. Our study identified 25 differentially abundant taxa that could differentiate preterm and full-term birth groups. A preterm birth prediction model was developed using machine learning of oral microbiome compositions in mouthwash samples. Findings of this study suggest the potential of using oral microbiome for predicting preterm birth. Further multi-center and larger studies are required to validate our results before clinical applications.

The Salivary Microbiome During Pregnancy: Associations With Clinical and Sociodemographic Characteristics

PURPOSE

Poor oral health has been associated with adverse pregnancy outcomes, and the oral microbiome may play a role in these mechanisms. We aimed to examine the salivary microbiome for alterations in diversity or relative abundance throughout pregnancy and its associations with adverse pregnancy outcomes and sociodemographic characteristics.

STUDY DESIGN AND METHODS

We conducted an ancillary study from a previous cohort study of 37 women during their second and third trimesters of pregnancy using preexisting, participant-collected salivary samples to examine the oral microbiome using 16S rRNA sequencing.

RESULTS

The salivary microbiome demonstrated stability throughout pregnancy, as there were no significant differences in alpha or beta diversity. Individuals who were diagnosed with preeclampsia had differences in beta diversity at the genus level (F = 2.65, df = 1, P = .015). There were also differences in beta diversity at the species level in Hispanic individuals compared with non-Hispanic individuals (F = 1.7183, df = 1, P = .04).

CONCLUSION

The salivary microbiome demonstrated stability throughout the second and third trimesters but may be different in Hispanics or those diagnosed with preeclampsia. As such, clinical providers need to demonstrate culturally competent care during pregnancy and continue to educate women about the importance of oral healthcare during the perinatal period. Future research is needed to examine the mechanisms associated with oral microbiome dysbiosis in Hispanic women during pregnancy and in women with preeclampsia.

Extracellular Vesicles of Porphyromonas gingivalis Disrupt Trophoblast Cell Interaction with Vascular and Immune Cells in an In Vitro Model of Early Placentation

Extracellular vesicles released by the primary pathogen of periodontal disease Porphyromonas gingivalis (Pg), referred to as outer membrane vesicles (OMVs), have been associated with the pathogenesis of systemic diseases like cardiovascular disease, rheumatoid arthritis, and Alzheimer's disease. A pathogenic role for Pg by disrupting placental homeostasis was proposed in the association between periodontal disease and adverse pregnancy outcomes. On the basis that trophoblast-derived factors modulate endothelial and immune cell profiles in normal pregnancy and the scarce presence of Pg in placenta, we hypothesized that OMVs from Pg affect trophoblast cell phenotype, impairing trophoblast-endothelium and trophoblast-neutrophil interactions. By means of in vitro designs with first-trimester human trophoblast cells, endothelial cells, and freshly isolated neutrophils, we showed that Pg OMVs are internalized by trophoblast cells and modulate the activity and expression of functional markers. Trophoblast cells primed with Pg OMVs enhanced neutrophil chemoattraction and lost their anti-inflammatory effect. In addition, reduced migration with enhanced adhesion of monocytes was found in endothelial cells upon incubation with the media from trophoblast cells pretreated with Pg OMVs. Taken together, the results support a pathogenic role of Pg OMVs at early stages of pregnancy and placentation through disruption of trophoblast contribution to vascular transformation and immune homeostasis maintenance.

Oral microbiome and preterm birth

Background

The etiology of preterm birth (PTB) is heterogeneous and not yet well known. Maternal periodontal disease has been investigated for decades and is a known risk factor for adverse pregnancy outcomes. However, no particular bacterial species or higher taxonomic order has been found as causative of PTB, leading to studies of the whole oral microbiome. In order to determine if and how the composition of the oral microbiome is associated with PTB, we performed a large case-control study including women with term (TB) and PTB.

Methods

We compared oral microbiomes in PTB to TB, to examine differences in the microbial richness, diversity, and differential abundance of specific taxa. We obtained oral swab samples from 152 Caucasian pregnant women who were classified as either PTB (≤36 6/7 weeks, n = 61) or TB (≥38 0/7 weeks, n = 91) in exclusion of any other major medical or obstetric conditions. The oral microbiomes of these women were characterized by 16S ribosomal RNA (rRNA) gene sequencing of the V3-V4 region on the MiSeq platform.

Results

The dominant microorganisms at the phylum level in all pregnant women regardless of birth week outcomes as belonging to Firmicutes, Proteobacteria, Bacteroidetes, Fusobacteria, and Actinobacteria. The phyla Firmicutes and Bacteroidetes were relatively more abundant in women with a PTB than in women with a TB, while Proteobacteria was less prevalent in women with a PTB. At the genus level, Veillonella, Prevotella, and Capnocytophaga were enriched in the PTB, and while many of the members of these genera could not be resolved to the species level, Veillonella massillensis was shown to be increased in the PTB group.

Conclusion

We identified the genera Veillonella, Prevotella, and Capnocytophaga in the maternal oral microbiome as being associated with PTB independently of clinically apparent infection, uterine anomalies, and other pregnancy complications, including placenta previa, and placental abruption. The clarification of the role of those taxa in the etiology of PTB merits further research.

[Developments in Research on the Relationship Between Porphyromonas gingivalis and Non-Oral Diseases]

Porphyromonas gingivalis ( P. gingivalis) is a common periodontal pathogen. Recently, there has been increasing evidence suggesting that P. gingivalis is not only a common pathogen in the oral cavity, but is also closely associated with non-oral diseases, including inflammatory bowel disease, cancer, cardiovascular diseases, Alzheimer's disease, rheumatoid arthritis, diabetes mellitus, premature birth and non-alcoholic hepatitis, etc. Herein, we reviewed the developments in recent years in research on the relationship between P. gingivalis, a periodontal pathogen, and non-oral diseases, which will help determine whether P. gingivalis could be used as an auxiliary diagnostic biomarker or a potential therapeutic target for these non-oral diseases, thus contributing to the development of treatment strategies for the relevant diseases.

Characterizing the supragingival microbiome of healthy pregnant women

The ecological characteristics and changes of the supragingival plaque microbial community during pregnancy are poorly understood. This study compared the microbial community characteristics of supragingival plaque in pregnant and non-pregnant women, with the aim of identifying specific microbial lineages and genera that may be associated with pregnancy. Thirty pregnant women were randomly selected from the First Affiliated Hospital of Xinjiang Medical University and divided into groups based on pregnancy trimester: first trimester (group P1, n=10, ≤12 weeks), second trimester (group P2, n=10, 13–27 weeks), and third trimester (group P3, n=10, 28–40 weeks). Ten healthy non-pregnant women (group N) were enrolled as the control group. Supragingival plaque samples of all subjects were collected and oral microbial composition was surveyed using a 16S rRNA gene sequencing approach. Statistical analysis was performed using a nonparametric test. The Chao 1 index of P3 was significantly lower compared with that of N, P1, and P2 (P<0.05). The Simpson indices of P2 and P3 were significantly higher than that of N (P<0.05). The Shannon index of P2 was significantly higher compared with that of N (P<0.05). Principal coordinate analysis (PCoA) showed different clustering according to the pregnancy status. Linear discriminant analysis effect size (LEfSe) revealed that the microbial species in group N that were significantly different from those of other groups were concentrated in the genus Neisseria. Species in P1 that were significantly different from those of other groups were concentrated in the genus Tannerella, while those in P2 and P3 were concentrated in the genus Leptotrichia. A total of 172 functional pathways were predicted for the bacterial communities in this study using PICRUSt2. Principal Component Analysis (PCA) showed that most predicted functional pathways clustered together in N and P1 and in P2 and P3. LEfSe analysis revealed that 11 pathways played a discriminatory role in the four groups. This work suggests a potential role of pregnancy in the formation of supragingival plaque microbiota and indicates that physiological changes during pregnancy may convert supragingival plaque into entities that could cause harm, which may be a risk factor for maternal health. Furthermore, findings from the study provide a basis for etiological studies of pregnancy-associated oral ecological disorders.

Effects of an Ozonated Water Irrigator on the Plaque Index and Bleeding Index of Pregnant Women

Pregnancy causes physiological changes in the woman’s body, which can also affect oral health. Therefore, pregnant women may manifest gingival inflammation that is favored by their hormonal increase. This clinical trial (ClinicalTrials.gov Identifier: NCT04140643) evaluated the variation in the plaque index (PI) or bleeding index (BOP) in pregnant women after daily use of an ozonated water irrigator and proper home oral hygiene, compared to a control group who only performed home oral hygiene. The inclusion criteria were the gestation period from the 14th week to the 30th week, a diagnosis of gingivitis, and a minimum number of teeth equal to 20. The PI and BOP index were evaluated at T0, fifteen days after T0 (T1), and two months after T1 (T2). The PI values systematically decreased over time (F (1.19) = 41.82) in both groups, with a systematic difference in PI values between the two groups (F (1.19) = 6.28, p = 0.021). A statistically significant difference was assessed in the BOP index at T2 between the two groups, with the control group suffering a higher BOP index. The results show that the patients in the study group showed a decrease in the BOP index over the three time points, in contrast to the control group, due to the beneficial properties of ozonated water.