Sex Steroid Hormones as a Balancing Factor in Oral Host Microbiome Interactions

Association of endogenous sex hormone levels with tooth loss due to periodontitis in men and post-menopausal women: The multi-ethnic study of atherosclerosis

AIM

To investigate the association between endogenous sex hormone levels and history of tooth loss related to periodontitis in healthy middle-aged to older men and post-menopausal women.

METHODS

This cross-sectional study included 5649 participants aged 45-84 (mean age, 63 ± 10 years) from the Multi-Ethnic Study of Atherosclerosis cohort who had sex hormone levels measured and answered a questionnaire regarding perceived periodontal status at exam 1. Multivariable logistic regression was used to examine the association of sex hormones (exposure) with history of tooth loss (outcome), stratified by sex.

RESULTS

Among post-menopausal women, higher free testosterone (per 1SD) was associated with a greater prevalence of tooth loss [OR 1.49 (95% CI, 1.08-2.05)], whereas higher sex hormone binding globulin (SHBG) was associated with a lower prevalence of tooth loss [OR 0.74 (0.58-0.94)], after adjustment for cardiometabolic risk factors and reproductive factors. In men, higher free testosterone and lower SHBG were associated with a lower prevalent probability of tooth loss in unadjusted analysis, but these associations lost significance after covariate adjustment.

CONCLUSION

A higher androgenic sex hormone profile in post-menopausal women (i.e., increased free testosterone, lower SHBG) was associated with an increased prevalence of tooth loss, after adjusting cardiometabolic risk factors. No such association was found in men. These findings suggest that sex hormones may influence or serve as a marker for periodontal health.

Association between Salivary Hormones, Dental Caries, and Cariogenic Microorganisms during Pregnancy

Objective: This study aimed to identify the salivary levels of six hormones (progesterone, estradiol, testosterone, cortisol, thyroxine T3, and triiodothyronine T4) in pregnant women, and to assess the association between salivary hormones, dental caries, and cariogenic microorganisms. Methods: This cross-sectional study included 181 low-income US pregnant women who were in their third trimester. Demographic details, oral hygiene practices, and medical backgrounds were obtained via questionnaires and medical records. Calibrated dentists obtained data on plaque index and caries status through comprehensive oral examinations. Unstimulated saliva was collected 2 h before eating and brushing. Salivary hormones were measured with a multiplex assay. Oral Streptococcus mutans (S. mutans) and Candida albicans (C. albicans) were quantified via colony-forming unit (CFU) counts. A latent model was used to generate clusters of pregnant women based on salivary hormone levels, followed by post-clustering analysis. Factors associated with salivary cariogenic microorganisms were further evaluated via multiple regression analyses. Results: Estradiol, progesterone, testosterone, cortisol, T3, and T4 in saliva were detectable at rates of 92%, 97%, 77%, 99%, 71%, and 50%, respectively. Three distinct participant clusters (high, intermediate, and low) were identified based on salivary hormone levels. Intermediate-level and high-level clusters had increased numbers of decayed teeth, decayed surfaces, ICDAS scores, and salivary S. mutans and C. albicans, compared to the low-level cluster (p < 0.05). Covariate analysis demonstrated that the high-level cluster was positively associated with salivary carriage of S. mutans (CFU/mL) (p < 0.05). Participants with higher levels of progesterone, estradiol, testosterone, and cortisol were associated with a high carriage status of S. mutans in saliva (>105 CFU/mL) (p < 0.05). Conclusions: This study demonstrated the feasibility of detecting salivary hormones during pregnancy and revealed the positive association between salivary steroid hormones and cariogenic pathogens.

Salivary microbiome and MRP-8/14 levels in children with gingivitis, healthy children, and their mothers

BACKGROUND

Gingivitis is the most common form of periodontal disease among children and adolescents and is associated with disrupted host-microbiome homeostasis. Family is an important factor influencing the prevalence of gingivitis. In the present study, we investigated the salivary microbiome, oral hygiene habits, and the salivary level of myeloid-related protein (MRP)-8/14 in children aged 7-12 years with gingivitis, periodontally healthy children, and their mothers.

METHODS

This study included 24 children with gingivitis (including four sibling pairs) and 22 periodontally healthy children (including two sibling pairs) and their mothers. The whole saliva was collected, DNA was extracted, the variable V3-V4 region of the eubacterial 16S ribosomal RNA gene was amplified, and sample library preparation was performed according to the Illumina protocol. The salivary levels of MRP-8/14 were analyzed by ELISA.

RESULTS

Alpha diversity of the salivary microbiome was considerably higher in gingivitis children and mothers of gingivitis children compared to healthy children and their mothers, respectively. Significant differences in beta diversity between healthy and gingivitis children, healthy children and their mothers, and gingivitis children and their mothers were detected. Overall, the number of common core amplicon sequence variants between children and their own mothers was significantly higher than between children and other mothers. The salivary MRP-8/14 levels in children with gingivitis were significantly higher compared to healthy children; a similar tendency was also mentioned for mothers.

CONCLUSION

Our study underlines the importance of family as an essential factor influencing oral health.

Oral microbiota of adolescents with dental caries: A systematic review

OBJECTIVE

This systematic review summarizes the current knowledge on the association between the oral microbiota and dental caries in adolescents.

DESIGN

An electronic search was carried out across five databases. Studies were included if they conducted research on generally healthy adolescents, applied molecular-based microbiological analyses and assessed caries status. Data extraction was performed by two reviewers and the Newcastle-Ottawa Scale was applied for quality assessment.

RESULTS

In total, 3935 records were reviewed which resulted in a selection of 20 cross-sectional studies (published 2005-2022) with a sample size ranging from 11 to 614 participants including adolescents between 11 and 19 years. The studies analyzed saliva, dental biofilm or tongue swabs with Checkerboard DNA-DNA hybridization, (q)PCR or Next-Generation Sequencing methods. Prevotella denticola, Scardoviae Wiggsiae, Streptococcus sobrinus and Streptococcus mutans were the most frequently reported species presenting higher abundance in adolescents with caries. The majority of the studies reported that the microbial diversity was similar between participants with and without dental caries.

CONCLUSION

This systematic review is the first that shows how the oral microbiota composition in adolescents appears to differ between those with and without dental caries, suggesting certain taxa may be associated with increased caries risk. However, there is a need to replicate and expand these findings in larger, longitudinal studies that also focus on caries severity and take adolescent-specific factors into account.

The Role of Estrogen and Estrogen Receptors in Head and Neck Tumors

Head and neck squamous cell carcinoma (HNSCC) is the most common histological form of head and neck tumors (HNTs), which originate from the epithelium of the lips and oral cavity, pharynx, larynx, salivary glands, nasal cavity, and sinuses. The main risk factors include consumption of tobacco in all forms and alcohol, as well as infections with high-risk human papillomaviruses or the Epstein-Barr virus. Regardless of the etiological agent, the risk of developing different types of HNTs is from two to more than six times higher in males than in females. The reason for such disparities probably lies in a combination of both biological and psychosocial factors. Therefore, it is hypothesized that exposure to female sex hormones, primarily estrogen, provides women with protection against the formation and metastasis of HNTs. In this review, we synthesized available knowledge on the role of estrogen and estrogen receptors (ERs) in the development and progression of HNTs, with special emphasis on membrane ERs, which are much less studied. We can summarize that in addition to epidemiologic studies unequivocally pointing to the protective effect of estrogen in women, an increased expression of both nuclear ERs, ERα, and ERβ, and membrane ERs, ERα36, GPER1, and NaV1.2, was present in different types of HNSCC, for which anti-estrogens could be used as an effective therapeutic approach.

Temporal changes in ewe vaginal microbiota throughout gestation

Introduction

Numerous factors are known to influence reproductive efficiency in ewes, but few studies have investigated the potential role of vaginal microbiota in sheep reproductive success. The objective of this study was to thoroughly characterize the ewe vaginal microbiota throughout the course of pregnancy.

Methods

Vaginal samples were collected from 31 pregnant Hampshire and Hampshire X Suffolk crossbred ewes on a weekly basis from pre-breeding to pregnancy testing and then biweekly until just after lambing. To characterize the vaginal microbial communities, DNA was extracted and 16S rRNA gene Illumina MiSeq amplicon sequencing was performed.

Results and Discussion

Alpha diversity metrics indicated an increase in species richness, evenness, and overall diversity throughout gestation. Distinct shifts in the bacterial communities were observed during gestation and were segregated into three periods: early gestation, a transitional period and mid/late gestation. During early gestation, Actinobacillus, Histophilus, and unclassified Leptotrichiaceae were found in greater relative abundance. During the transitional period, a population shift occurred characterized by increasing relative abundance of Streptococcus and Staphylococcus. During mid/late gestation, Staphylococcus, Streptococcus, and Ureaplasma had the greatest relative abundance. These shifts in the microbial population throughout the ewe's gestation are likely related to hormonal changes triggered by the growing conceptus, specifically increasing blood concentration of progesterone. The transitional period shift in vaginal microbial communities potentially aligns with the placental take-over of progesterone production from the corpus luteum at approximately day 50 after conception (gestational week 7). Understanding the observed variability of the vaginal microbiota throughout pregnancy will allow for future comparison of ewes that did not become pregnant or had abnormal pregnancies, which could lead to the discovery of potential bacterial biomarkers for pregnancy outcome; this understanding could also lead to development of probiotics to improve sheep reproductive success.

Late Complications in Long-Term Childhood Cancer Survivors: What the Oral Health Professional Needs to Know

With diagnostic and therapeutic advances, over 80% of children diagnosed with cancer become long-term survivors. As the number of childhood cancer survivors (CCS) continues to increase, dental practitioners become more likely to have CCS among their patients. CCS may develop late complications from damage caused by their cancer treatment to endocrine, cardiovascular, musculoskeletal, and other organ systems. These complications may surface decades after the completion of treatment. Adverse outcomes of childhood cancer treatment frequently involve oral and craniofacial structures including the dentition. Tooth development, salivary gland function, craniofacial growth, and temporomandibular joint function may be disturbed, increasing oral health risks in these individuals. Moreover, CCS are at risk of developing subsequent malignancies, which may manifest in or near the oral cavity. It is important that dental practitioners are aware of the childhood cancer history of their patients and have knowledge of potential late complications. Therefore, this narrative review aims to inform dental practitioners of late oral complications of cancer treatment modalities commonly used in pediatric oncology. Furthermore, selected common non-oral late sequelae of cancer therapy that could have an impact on oral health and on delivering dental care will be discussed.

The effect of sex steroid hormones on the ecology of in vitro oral biofilms

Sex steroid hormones (SSH) such as oestrogen, progesterone and testosterone are cholesterol derived molecules that regulate various physiological processes. They are present in both blood and saliva, where they come in contact with oral tissues and oral microorganisms. Several studies have confirmed the effect of these hormones on different periodontal-disease-associated bacteria, using single-species models. Bacteria can metabolize SSH, use them as alternative for vitamin K and also use them to induce the expression of virulence factors. However, it is still unclear what the effects of SSH are on the oral microbiome. In this study, we investigated the effects of four SSH on commensal in vitro oral biofilms. Saliva-derived oral biofilms were grown in Mc Bain medium without serum or menadione using the Amsterdam Active-Attachment model. After initial attachment in absence of SSH, the biofilms were grown in medium containing either oestradiol, oestriol, progesterone or testosterone at a 100-fold physiological concentration. Menadione or ethanol were included as positive control and negative control, respectively. After 12 days with daily medium refreshments, biofilm formation, biofilm red fluorescence and microbial composition were determined. The supernatants were tested for proteolytic activity using the Fluorescence Resonance Energy Transfer Analysis (FRET). No significant differences were found in biofilm formation, red fluorescence or microbial composition in any of the tested groups. Samples grown in presence of progesterone and oestradiol showed proteolytic activity comparable to biofilms supplemented with menadione. In contrast, testosterone and oestriol showed a decreased proteolytic activity compared to biofilms grown in presence of menadione. None of the tested SSH had large effects on the ecology of in vitro oral biofilms, therefore a direct translation of our results into in vivo effects is not possible. Future experiments should include other host factors such as oral tissues, immune cells and combinations of SSH as present in saliva, in order to have a more accurate picture of the phenomena taking place in both males and females.

Prevalence, Severity of Extension, and Risk Factors of Gingivitis in a 3-Month Pregnant Population: A Multicenter Cross-Sectional Study

The scope of this study was to assess the prevalence, severity of extension, and risk factors of gingivitis among pregnant women. In this cross-sectional study, 220 nulliparous women at 3 months of pregnancy were recruited in 2022 at the first obstetrical visit in Dakar, Senegal. Demographic characteristics, lifestyle habits, prenatal clinical status, and oral clinical parameters were recorded. Multivariable logistic regression modeling was used to assess relationships between gingivitis and risk factors. Eighty-eight percent of women had gingivitis, 15% were classified as moderate and 73% as severe. A total of 66.7% (95% CI [28.8-92.1]) of the sites had bleeding on interdental brushing. The odds for gingivitis decreased significantly for women consuming more than five portions of fruits and vegetables per day (OR = 0.15; 95% CI [0.03-0.66]) and increased in women who had a professional activity (OR = 6.75; 95% CI [1.27-35.87]) and high education. Concomitantly, the percentage of dental plaque (OR = 131.6; 95% CI [10.80-1619.71] and the severity of clinical attachment loss (OR = 7.70; 95% CI [3.16-18.92]) were important risk factors. Inverse associations were observed with increasing body mass index (OR = 0.76; 95% CI [0.63-0.93]). Our results underline that gingivitis cases and bleeding were particularly high among 3-month pregnant women. Literacy and adequate oral hygiene actions to modify behaviors and to achieve meticulous biofilm disorganization could make a favorable change in the gingival health outcome. Additionally, further research is necessary to precisely determine the role of biofilm-induced gingivitis and systemic-induced gingivitis in improving gingival conditions.

Oral microbiome variations related to ageing: possible implications beyond oral health

The global population is getting older due to a combination of longer life expectancy and declining birth rates. Growing evidence suggests that the oral microbiota composition and distribution may have a profound effect on how well we age. The purpose of this study was to investigate age-related oral microbiome variations of supragingival plaque and buccal mucosa samples in the general population in Latvia. Our results indicated significant difference between supragingival plaque bacterial profiles of three age groups (20-40; 40-60; 60 + years). Within supragingival plaque samples, age group 20-40 showed the highest bacterial diversity with a decline during the 40-60 age period and uprise again after the age of 60. Among other differences, the important oral commensal Neisseria had declined after the age of 40. Additionally, prevalence of two well-documented opportunistic pathogens Streptococcus anginosus and Gemella sanguinis gradually rose with age within our samples. Furthermore, supragingival plaque and buccal mucosa samples significantly differed in overall bacterial composition.

The bidirectional relationship between periodontal disease and pregnancy via the interaction of oral microorganisms, hormone and immune response

Periodontal disease has been suggested to be linked to adverse pregnancy outcomes such as preterm birth, low birth weight, and preeclampsia. Adverse pregnancy outcomes are a significant public health issue with important clinical and societal repercussions. This article systematically reviews the available epidemiological studies involving the relationship between periodontal disease and adverse pregnancy outcomes over the past 15 years, and finds a weak but independent association between adverse pregnancy outcomes and periodontal disease. The bidirectional association and the potential mechanisms are then explored, focusing on three possible mechanisms: inflammatory reaction, oral microorganisms and immune response. Specifically, elevated systemic inflammation and increased periodontal pathogens with their toxic products, along with a relatively suppressed immune system may lead to the disruption of homeostasis within fetal-placental unit and thus induce adverse pregnancy outcomes. This review also explains the possible mechanisms around why women are more susceptible to periodontal disease. In conclusion, pregnant women are more likely to develop periodontal disease due to hormonal changes, and periodontal disease has also been suspected to increase the incidence of adverse pregnancy outcomes. Therefore, in order to lessen the risk of adverse pregnancy outcomes, both obstetricians and dentists should pay attention to the development of periodontal diseases among women during pregnancy.

Testosterone and estradiol modify the expression of adhesins and biofilm formation in Actinobacillus seminis

Actinobacillus seminis is the causal agent of epididymitis and has other effects on the reproductive tracts of small ruminants and bovines. This bacterium causes infection when luteinizing (LH) or follicle-stimulating hormones increase, and hosts reach sexual maturity. LH induces female ovulation and male testosterone production, suggesting that these hormones affect A. seminis pathogenicity. In the present study, we evaluated the effect of testosterone (1-5 ng/ml) or estradiol (5-25 pg/ml) added to culture medium on the in vitro growth, biofilm production, and adhesin expression of A. seminis. Estradiol does not promote the growth of this bacterium, whereas testosterone increased A. seminis planktonic growth 2-fold. Both hormones induced the expression of the elongation factor thermo unstable (EF-Tu) and phosphoglycerate mutase (PGM), proteins that A. seminis uses as adhesins. Estradiol (5 or 10 pg/ml) decreased biofilm formation by 32%, whereas testosterone, even at 5 ng/ml, showed no effect. Both hormones modified the concentrations of carbohydrates and eDNA in biofilms by 50%. Amyloid proteins are characterized by their capacity to bind Congo red (CR) dye. Actinobacillus seminis binds CR dye, and this binding increases in the presence of 5-20 pg/ml estradiol or 4 ng/ml testosterone. The A. seminis EF-Tu protein was identified as amyloid-like protein (ALP). The effect of sexual hormones on the growth and expression of virulence factors of A. seminis seems to be relevant for its colonization and permanence in the host.

The oral microbiome in young women at different stages of periodontitis: Prevotella dominant in stage III periodontitis

Objective

Periodontitis progression is related to the dynamic dysbiosis of oral microbiome. We identified the dominant bacteria and the potential pathway in young women with stage-III periodontitis.

Materials and methods

Samples of subgingival plaque were collected from 26 young women with periodontitis (20 with stage-I and 6 with stage-III). Using 16S rRNA-sequencing, we determined the variation in oral bacterial communities of the two groups, and identified the dominant bacteria of each group. We used the Kyoto Encyclopedia of Genes and Genomes (KEGG) database to evaluate the signaling pathways related to the difference in oral bacterial composition. The role of the dominant bacteria of stage-III periodontitis was investigated in vivo and in vitro using an endoplasmic reticulum stress inhibitor.

Results

Young women with stage-I periodontitis had higher values for the Chao1 Index, Observed Species and Phylogenetic Diversity Whole Tree Index than those for women with stage-III periodontitis. β-diversity analyses revealed that samples could be divided into different groups according to the periodontitis stage. The most representative biomarkers of stage-III periodontitis in young women were bacteria of the phylum Bacteroidetes, its order, family and genera Bacteroidales, Prevotellaceae and Prevotella. The KEGG database revealed that the change in oral bacterial composition of young women with stage-III periodontitis may be related to protein processing in an endoplasmic reticulum pathway. Salubrinal (an endoplasmic reticulum stress regulator) controlled expression of Runx2, Col1a1, Ocn in mouse bone-marrow mesenchymal cells. Salubrinal administration showed that moderate endoplasmic reticulum stress inhibited alveolar bone loss in periodontitis induced by Prevotella intermedia lipopolysaccharide.

Conclusion

Differences between periodontitis stages were noted and bacteria of Prevotella species were abundant in young women with stage-III periodontitis. This phenomenon was related to protein processing in an endoplasmic reticulum pathway.

A Commentary on the Potential Use of Oral Microbiome in Prediction, Diagnosis or Prognostics of a Distant Pathology

In health, the oral microbiome is in balance with its host. If this balance is lost, this symbiosis is replaced by dysbiotic microbial communities, which are thought to affect the rest of the body either directly or via metabolites or pro-inflammatory molecules. The association of oral microbiome with general health has led to attempts to use oral microbial biomarkers for the prediction, diagnosis or prognosis of distant pathologies such as colorectal carcinoma or pancreatic cancer. These attempts however have no chance to succeed if the complexity of the oral ecosystem and the interplay of environmental, behavioral and biological factors is not taken into account. Standardized, well-documented oral sample collection procedures together with detailed clinical oral examination and behavioral data are the prerequisites for the successful evaluation of the oral microbiome as a potential biomarker for distant pathologies.