The role of oral microbiome in periodontitis under diabetes mellitus

Breastfeeding patterns and total volume of human milk consumed influence the development of the infant oral microbiome

Background

The oral microbiome of breastfed infants is distinct from that of formula-fed infants. However, breastfeeding characteristics, such as time spent breastfeeding (min/24 h), breastfeeding frequency (number of breastfeeds per day), and human milk intake (ml/day) vary significantly between breastfeeding dyads.

Objectives

Given that human milk and breastfeeding exposures likely influence early colonisation of the infant oral microbiome, this study aimed to elucidate the impact of breastfeeding characteristics on the development of the infant oral microbiome.

Materials and methods

Oral swabs (n = 55) were collected from infants at three months of age, alongside breastfeeding data collected over a 24-hour period. Bacterial DNA profiles were analysed using full-length 16S rRNA gene sequencing.

Results

Variations in breastfeeding characteristics contributed to differences in microbial community structure. Total breastfeeding duration (min/24 h) was positively associated with Bifidobacterium longum and Lactobacillus gasseri, while breastfeeding frequency was negatively associated with Veillonella sp. Additionally, human milk intake (ml/24 h) was negatively associated with Streptococcus parasanguinis.

Conclusion

These findings underscore the significant influence of early life feeding practices on oral microbial communities and emphasise the importance role of breastfeeding in shaping the oral microbiome during early life.

Salivary microbiome and biomarker characteristics of diabetics with periodontitis

OBJECTIVE

To examine the characteristics of the salivary microbiome in Type 2 diabetes mellitus (T2DM) patients with or without periodontitis.

BACKGROUND

Periodontitis has been identified as clear sequelae of T2DM. This chronic oral disease also impacts the management of the clinical features of diabetes. The oral microbiome characteristics in T2DM with and without periodontitis, as well as the response of this oral microbiome to nonsurgical therapy have not been well described. Knowledge of key oral biological features could help address the observed poorer clinical presentation of T2DM patients.

METHODS

The oral microbiome in saliva of adult cohorts periodontally healthy/non-diabetic (non-periodontitis; NP; n = 31), T2DM without periodontitis (DWoP; n = 32), and T2DM with periodontitis (DWP; n = 29) were characterized by microbial molecular analysis using V3-V4 sequencing and Luminex or ELISA techniques for salivary host analytes.

RESULTS

Phyla distribution showed DWP with significantly lower levels of Firmicutes and Actinobacteria and higher levels of Fusobacteria and Spirochetes compared to the healthier groups. Approximately 10% of the detected microbial species showed significant differences in frequency and level of colonization among the DWP, DWoP, and NP samples. A subset of bacteria were significantly correlated with clinical disease features, as well as a specific repertoire of salivary analytes, in particular matrix metalloproteinase (MMP)8/MMP9, interleukin-1ß, B-cell activating factor, and resistin differed between the groups and were related to specific taxa. Principal component analysis that identified a majority of the DWP subjects microbiome was unique based upon an array of 27 taxa out of up to 255 detected in the saliva samples.

CONCLUSION

T2DM patients with periodontitis show unique oral microbiome and salivary analyte composition compared to diabetics or non-diabetic persons without periodontitis. Specific members of the oral microbiome relate directly to the clinical disease features and/or salivary biomolecules in T2DM individuals.

Oral Fusobacterium nucleatum resists the acidic pH of the stomach due to membrane erucic acid synthesized via enoyl-CoA hydratase-related protein FnFabM

Background and Objective

Oral bacteria can translocate to the intestine, and their colonization efficiency is influenced by the gastrointestinal tract pH. Understanding how oral bacteria resist acidic environments is crucial for elucidating their role in gut health and disease.

Methods

To investigate the mechanisms of acid resistance in oral bacteria, an in vitro gastrointestinal tract Dynamic pH Model was established. This model was used to simulate the acidic conditions encountered by bacteria during their translocation from the mouth to the intestine.

Results

Fusobacterium nucleatum exhibited the highest survival rate in an acidified fluid mimicking the stomach pH (pH 1.5). The survival was significantly increased in the presence of erucic acid C22:1(n9) in cell membranes. Phylogenetic tree analysis revealed that C22:1(n9) synthesis was significantly associated with FnFabM gene expression in F. nucleatum at pH 1.5. Inhibition of FnFabM expression by cerulenin reduced the C22:1(n9) content and decreased the colonization efficiency of F. nucleatum in the stomach and jejunum of mice.

Conclusions

Oral F. nucleatum translocate to the intestine by resisting the acidic environment owing to the presence of erucic acid in its cell membrane, which is regulated by FnFabM. These results provide novel insights into the mechanisms underlying the oral bacteria survival in acidic environments and their potential to colonize the intestine; thus, shedding light on the oral-gut axis and its implications on human health.

Evaluation of Soluble Tumor Necrosis Factor-Like Weak Inducer of Apoptosis, Omentin, and Tumor Necrosis Factor-α in Subjects with Periodontitis and Type 2 Diabetes Mellitus

Purpose: Periodontal disease worsens glycemic control due to the bidirectional link between periodontitis and type 2 diabetes mellitus (T2DM), involving inflammatory markers such as soluble tumor necrosis factor-like weak inducer of apoptosis (sTWEAK), tumor necrosis factor-α (TNF-α), and omentin-1. However, their combined role in T2DM with periodontitis has not been studied. This study aimed to evaluate the levels of these biomarkers in periodontitis patients with T2DM before and after nonsurgical periodontal therapy (NSPT). Materials and Methods: Sixty subjects were divided into four groups (15 each): Group I (systemically and periodontally healthy), Group II (systemically healthy with periodontitis), and Groups III and IV (periodontitis with T2DM, exhibiting good glycemic control [hemoglobin A1c (HbA1c) <7%] and poor control [HbA1c >8%]), respectively. Periodontal parameters such as plaque index, bleeding index, probing pocket depth, and clinical attachment level were assessed. Serum samples were collected at baseline and 3 months to measure sTWEAK, omentin-1, and TNF-α levels using ELISA. HbA1c levels were evaluated at baseline and 3 months. Results: TNF-α was significantly elevated in all groups compared with sTWEAK and omentin-1. However, omentin-1 levels were higher in the healthy group compared with all other groups. Periodontal parameters and biomarker levels showed significant improvement across all groups after 3 months post-NSPT. Conclusion: TNF-α and sTWEAK may serve as diagnostic markers, while omentin-1 can be a reliable prognostic marker for evaluating NSPT effects in T2DM patients with periodontitis and varying glycemic control.

Dynamics of the oral microbiome during orthodontic treatment and antimicrobial advances for orthodontic appliances

The oral microbiome plays an important role in human health, and an imbalance of the oral microbiome could lead to oral and systemic diseases. Orthodontic treatment is an effective method to correct malocclusion. However, it is associated with many adverse effects, including white spot lesions, caries, gingivitis, periodontitis, halitosis, and even some systematic diseases. Undoubtedly, increased difficulty in oral hygiene maintenance and oral microbial disturbances are the main factors in developing these adverse effects. The present article briefly illustrates the characteristics of different ecological niches (including saliva, soft tissue surfaces of the oral mucosa, and hard tissue surfaces of the teeth) inhabited by oral microorganisms. According to the investigations conducted since 2014, we comprehensively elucidate the alterations of the oral microbiome in saliva, dental plaque, and other ecological niches after the introduction of orthodontic appliances. Finally, we provide a detailed review of recent advances in the antimicrobial properties of different orthodontic appliances. This article will provide researchers with a profound understanding of the underlying mechanisms of the effects of orthodontic appliances on human health and provide direction for further research on the antimicrobial properties of orthodontic appliances.

Biofilm architecture and dynamics of the oral ecosystem

The oral cavity, being a nutritionally enriched environment, has been proven to be an ideal habitat for biofilm development. Various microenvironments, including dental enamel, supra- and subgingival surfaces, salivary fluid, and the dorsal surface of the tongue, harbor diverse microbes. These biofilms typically consist of four major layers. Depending on the food, age, clinical state, and lifestyle of the patient, the microbial growth dynamics in oral biofilm varies significantly. The presence of pathogenic bacteria that disrupt the normal floral composition of the oral cavity can lead to plaque biofilm formation, which is a precursor to various diseases. Noteworthy pathogenic bacteria, such as Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus mutans, often initiate biofilm formation. Undiagnosed and untreated oral biofilm can lead to severe diseases like periodontitis and eventual tooth loss. Therefore, studying the architecture and dynamics of oral biofilms is essential and can be achieved through image analysis and modern technologies, such as AI-enabled technologies and surface topography-adaptive robotic superstructures.

Integrated Analysis of Oral Microbiome and Metabolome in T2DM Patients With Varying Glycemic Status

OBJECTIVE

This study aimed to analyze the subgingival and salivary microbiome and metabolome in diabetic periodontitis patients with varying glycemic levels.

METHODS

Forty-two diabetic periodontitis patients were sampled of saliva, gingival crevicular fluid (GCF), and blood, and categorized into three groups based on systemic glycemic status. The microbiome was assessed using full-length 16S rRNA gene sequencing. Gas chromatography-mass spectrometry was performed for metabolome analysis.

RESULTS

The similarity in the structure and function of the flora in saliva and GCF was evident under good blood glucose control. Conversely, inadequate blood glucose control demonstrated a more distinct separation from saliva flora. Both salivary and GCF microorganisms exhibited greater periodontal pathogenicity, with salivary metabolites showing stronger associations with inflammation when Hemoglobin A1c (HbA1c) > 6.5%. Some periodontal pathogens, such as Veillonella atypica, showed significantly positive correlations with proinflammatory metabolites, including lactic acid and putrescine, etc. Salivary microbes demonstrated more sensitive responses than GCF to changes in blood glucose levels among type 2 diabetes mellitus (T2DM) patients.

CONCLUSION

Under active blood glucose control, it indicates lower periodontal pathogenicity and inflammatory correlation in the oral microecology of T2DM patients. Saliva appears to offer superior diagnostic and monitoring value compared to GCF in the context of systemic disease surveillance.

Oral Microbiome Research in Biopsy Samples of Oral Potentially Malignant Disorders and Oral Squamous Cell Carcinoma and Its Challenges

This study aims to evaluate the potential benefits and challenges of integrating oral microbiome research into the clinical management of oral potentially malignant disorders (OPMD) and oral squamous cell carcinoma (OSCC). The oral microbiome has gained significant attention for its role in the pathogenesis and progression of these conditions, with emerging evidence suggesting its value as a diagnostic and prognostic tool. By critically analyzing current evidence and methodological considerations, this manuscript examines whether microbiome analysis in biopsy samples can aid in the early detection, prognosis, and management of OPMD and OSCC. The complexity and dynamic nature of the oral microbiome require a multifaceted approach to fully understand its clinical utility. Based on this review, we conclude that studying the oral microbiome in this context holds significant promise but also faces notable challenges, including methodological variability and the need for standardization. Ultimately, this manuscript addresses the question, “Should such research be undertaken, given the intricate interactions of various factors and the inherent obstacles involved?”, and also emphasizes the importance of further research to optimize clinical applications and improve patient outcomes.

Causal relationship between diabetes mellitus and lung cancer: a two-sample Mendelian randomization and mediation analysis

Background

Diabetes mellitus (DM) is the common comorbidity with lung cancer (LC), and metabolic disorders have been identified as significant contributors to the pathogenesis of both DM and LC. The causality between diabetes mellitus and lung cancer is still controversial. Hence, the causal effects of DM on the risk of LC was systemically investigated, and the mediating role of blood metabolites in this relationship was further explored.

Methods

This study utilized a comprehensive Mendelian randomization (MR) analysis to investigate the association between diabetes mellitus and lung cancer. The inverse variance weighted method was employed as the principle approach. MR Egger and weighted median were complementary calculations for MR assessment. A two-step MR analysis was performed to evaluate the mediating effects of blood metabolites as potential intermediate factors. Simultaneously, sensitivity analyses were performed to confirm the lack of horizontal pleiotropy and heterogeneity.

Results

The two-sample MR analysis illustrated the overall effect of type 1 diabetes mellitus (T1DM) on lung squamous cell carcinoma (LUSC) (OR: 1.040, 95% CI: 1.010-1.072, p = 0.009). No causal connection was found between T2DM and the subtypes of lung cancer. Two-step MR identified two candidate mediators partially mediating the total effect of T1DM on LUSC, including glutamine conjugate of C6H10O2 levels (17.22%) and 2-hydroxyoctanoate levels (5.85%).

Conclusion

Our findings supported a potentially causal effect of T1DM against LUSC, and shed light on the importance of metabolites as risk factors in understanding this relationship.

Clinical and Microbiological Periodontal Biofilm Evaluation of Patients with Type I Diabetes

Background/Objectives: The purpose of this study was to assess the microbial composition and density of subgingival plaque samples for periodontal pathogens while correlating the values with glycemic control levels via glycated hemoglobin (HbA1c), a type of hemoglobin that has chemically linked glucose, in type I diabetes individuals who will undergo complex oral rehabilitation through orthodontic treatment and implant surgery. Methods: A cohort of 42 adults with type I diabetes were included in this study. The subjects sustained a comprehensive periodontal clinical examination as well as microbiological assessments of their subgingival plaque samples through quantitative real-time PCR. The samples were collected from the two deepest pockets of each subject. Results: The highest number of periodontopathogenic bacteria was observed in the pockets of 5-7 mm. T. forsythia showed the highest prevalence (20.48%), with decreasing numbers as follows: T. denticola (13.31%), P. gingivalis (11.26%), A. actinomycetemcomitans (7%), and P. intermedia (4.9%). T. denticola and T. forsythia were significantly more commonly observed in individuals with elevated HbA1c serum levels. No correlation was observed between P. gingivalis, A. actinomycetemcomitans, P. intermedia presence, and the HbA1c value. Conclusions: Periodontopathogenic agents' presence in subgingival biofilm samples varied in accordance with the pocket probing depth and metabolic control of the diabetic individuals. In our study, the appearance of these periodontopathogenic agents was linked to lowered metabolic control in patients with type I diabetes mellitus.

Alterations in subgingival microbiome and advanced glycation end-products levels in periodontitis with and without type 1 diabetes mellitus: a cross-sectional study

BACKGROUND

Existing studies predominantly focused on the relationship between periodontitis and type 2 diabetes mellitus (T2DM), with limited data on the association between periodontitis and type 1 diabetes mellitus (T1DM). This study aimed to examine the impact of T1DM and periodontitis on the subgingival microbiome and levels of advanced glycation end-products (AGEs).

METHODS

Samples were collected from four groups: T1DM, periodontitis (P), T1DM with periodontitis (DP), and periodontally and systemically healthy controls (Control). Subgingival microbiome composition and AGE levels were assessed using 16S rRNA gene sequencing and enzyme-linked immunosorbent assay (ELISA), respectively. Correlations between clinical indexes, microbiome composition, and AGEs were analyzed using Spearman correlation coefficient.

RESULTS

Alpha and beta diversity analyses revealed significant differences in bacterial diversity between the DP group and other groups. Linear discriminant analysis effect size (LEfSe) analysis identified specific bacteria influencing each group: Acinetobacter, Leptotrichia, Raoultibacter, and Veillonella in the Control group; Tannerella, Porphyromonas, Filifactor, and Treponema in the P group; and Lactobacillales in T1DM individuals. Prevotella and Selenomonas were notably influential in the DP group. PICRUSt2 analysis showed pathways alterations were concentrated in cell motility, translation, cell growth and death and metabolism in the DP and P groups. Spearman correlation analysis indicated a positive correlation between AGEs and periodontitis or diabetes-related parameters and AGEs were positively correlated with Haemophilus and Arachnia.

CONCLUSIONS

The findings suggested that the composition and function of the subgingival microbiome in the P group with or without T1DM were significantly different. Additionally, AGEs were involved in the development of periodontitis even in absence of hyperglycemia.

Multifunctional Nanoemulsified Clinacanthus nutans Extract: Synergistic Anti-Pathogenic, Anti-Biofilm, Anti-Inflammatory, and Metabolic Modulation Effects against Periodontitis

This study investigates the therapeutic potential of Clinacanthus nutans extracts, focusing on the 95% ethanol (95E) extract and its nanoemulsified form, against oral pathogens and their bioactive effects. The findings demonstrate potent antibacterial activity against Streptococcus mutans and Staphylococcus aureus, essential for combating periodontal diseases, and significant anti-biofilm properties crucial for plaque management. Additionally, the extracts exhibit promising inhibitory effects on α-glucosidase enzymes, indicating potential for diabetes management through glucose metabolism regulation. Their anti-inflammatory properties, evidenced by reduced nitric oxide production, underscore their potential for treating oral infections and inflammation. Notably, the nanoemulsified 95E extract shows higher efficiency than the conventional extract, suggesting a multifunctional treatment approach for periodontal issues and metabolic disorders. These results highlight the enhanced efficacy of the nanoemulsified extract, proposing it as an effective treatment modality for periodontal disease in diabetic patients. This research offers valuable insights into the development of innovative drug delivery systems using natural remedies for improved periodontal care in diabetic populations.

Antibacterial periodontal ligament stem cells enhance periodontal regeneration and regulate the oral microbiome

BACKGROUND

The transplantation of periodontal ligament stem cells (PDLSCs) has been shown to enhance periodontal regeneration in animal models and clinical trials. However, it is not known whether PDLSCs are antibacterial and whether this affects oral microbiota and periodontal regeneration.

METHODS

We isolated human PDLSCs from periodontal ligament of extracted teeth. Rats' periodontal fenestration defects were prepared, and treated with PDLSC injections (Cell group), using saline injections (Saline group) as the control. The oral microbiota was explored by 16 S rDNA sequencing and compared with that before surgery (PRE group). The antibacterial property of PDLSCs and its underlying mechanism were tested in vitro.

RESULTS

Microbiome analyses reveal a decreased biodiversity, a changed community structure, and downregulated community functions of the oral microbiome in the Saline group. PDLSCs injections enhance periodontal regeneration, reverse the decrease in diversity, and increase the abundance of non-pathogenic bacterial Bifidobacterium sp. and Lactobacillus sp., making the oral microbiome similar to that of the PRE group. In vitro, PDLSCs inhibit the growth of Staphylococcus aureus, Escherichia coli, and Fusobacterium nucleatum. The main mechanism of action is postulated to involve production of the cationic antimicrobial peptide LL-37.

CONCLUSIONS

Our findings reveal that PDLSC injections enhance periodontal regeneration and regulate the oral microbiome to foster an oral cavity microenvironment conducive to symbiotic microbiota associated with health.

Efficacy of adjunctive local periodontal treatment for type 2 diabetes mellitus patients with periodontitis: A systematic review and network meta-analysis

OBJECTIVES

To investigate the effectiveness of different adjunctive local treatments combined with non-surgical periodontal therapy (NSPT) to reduce pocket depth (PD), gain clinical attachment level (CAL), and/or reduce glycated hemoglobin (HbA1c) in individuals with both type 2 diabetes mellitus (T2DM) and periodontitis in a systematic review and network meta-analysis.

DATA SOURCES

Publications were searched in Cochrane databases, EMBASE, Google Scholar, MEDLINE, PubMed, opengrey.eu, and www.

CLINICALTRIALS

gov up to May 29, 2024 with no language restriction.

STUDY SELECTION

Only randomized controlled trials (RCTs) were included. Network meta-analysis utilized frequentist models.

DATA

The network meta-analysis of 30 RCTs involving 1224 patients revealed that, in short-term (2-3 months) and medium-term (4-6 months), adjunctive local treatment involving statins or metformin significantly outperformed scaling and root planning (SRP) with/without additional interventions such as photodynamic and laser therapies (PDT/LT), phytotherapy, doxycycline, bisphosphonates, antibiotics, antiseptics, or placebo for reducing PD and/or gaining CAL. In the long-term (>6 months), statins yielded the most significant additional PD reduction and CAL gain, followed by antibiotics, compared to SRP with antiseptics or placebo. Only PDT/LT demonstrated significantly greater HbA1c reduction in the short term compared to SRP with/without statins, antiseptics, or placebo.

CONCLUSION

This study moderately supports that adding metformin or statins locally to NSPT may enhance PD reduction and CAL gain compared to SRP with/without placebo.

CLINICAL SIGNIFICANCE

Clinicians are guided to optimize adjunctive therapies, enhancing the health of patients with type 2 diabetes and periodontitis. A strategic approach is proposed to tackle systemic and oral health challenges simultaneously.

Periodontitis associated with risk of obstructive sleep apnea in Peruvian adult patients: A cross-sectional study

BACKGROUND

Patients at high risk for obstructive sleep apnea (OSA) are characterized by intermittent transient hypoxias and upper respiratory tract collapse, with reactive oxygen production and oxidative imbalance which causes an inflammatory cascade. This can generate negative effects on the periodontium, causing severe tooth attachment loss. This study aimed to determine the association between periodontitis and the risk of OSA in adults who attend outpatient otolaryngology consultations.

MATERIAL AND METHODS

A cross-sectional observational study was carried out with 118 patients seen in the otolaryngology service of the Hospital Victor Lazarte Echegaray-ESSALUD in Trujillo (Peru), between September and October 2023. The presence and severity of periodontitis were determined using the Page and Eke criteria, and the presence and severity of OSA risk were determined using the STOP-BANG questionnaire. The results were analyzed using Chi-square, Spearman correlation and logistic regression tests, considering a significance level of p<0.05.

RESULTS

An association was found between periodontitis and risk of OSA (p=0.000), obtaining a positive relationship with rs=0.527. In addition, there was an association between periodontitis and DM2 (p=0.028) and bronchial asthma (0.017). No association was found between periodontitis and sex (0.503) or age (0.741).

CONCLUSIONS

There is an association between periodontitis and the risk of OSA in Peruvian adult patients who attended outpatient otolaryngology consultations. This association was also found according to age, sex, smoking, DM2 and asthma. In addition, an association was found between periodontitis and DM2 and asthma, but not with sex and age.

Lipocalin-2 as a fundamental protein in type 2 diabetes and periodontitis in mice

BACKGROUND

Lipocalin-2 (LCN-2) is an osteokine that suppresses appetite, stimulates insulin secretion, regulates bone remodeling, and is induced by proinflammatory cytokines. The aim of this work was to investigate the participation of LCN-2 in periodontitis associated with type 2 diabetes (T2D) by evaluating alveolar bone loss, glycemic control, inflammation, and femur fragility.

METHODS

A murine model of periodontitis with T2D and elevated LCN-2 concentration was used. Functional LCN-2 inhibition was achieved using an anti-LCN-2 polyclonal antibody, and isotype immunoglobulin G was used as a control. The alveolar bone and femur were evaluated by micro-CT. Glucose metabolism was determined. Tumor necrosis factor (TNF-α) and receptor activator of nuclear factor kappa-B ligand (RANKL) levels in alveolar bone lysates were quantified using ELISA, and serum cytokines were quantified using flow cytometry. A three-point bending test was performed in the femur, and RANKL levels were measured in femur lysates using ELISA.

RESULTS

Functional inhibition of LCN-2 in T2D-periodontitis mice decreased alveolar bone loss in buccal and palatal surfaces and preserved the microarchitecture of the remaining bone, decreased TNF-α and RANKL in alveolar bone, reduced hyperglycemia, glucose intolerance, and insulin resistance, and increased insulin production through improving the functionality of pancreatic β cells. Furthermore, this inhibition increased serum free-glycerol levels, decreased serum interleukin (IL)-6, increased serum IL-4, and reduced femur fragility and RANKL expression in the femur.

CONCLUSIONS

LCN-2 participates in periodontitis associated with T2D. Inhibiting its function in mice with T2D and periodontitis improves pancreatic β-cell function, and glucose metabolism and decreases inflammatory cytokines and bone-RANKL levels, which results in the preservation of femoral and alveolar bone microarchitecture.

PLAIN LANGUAGE SUMMARY

In this study, we explored the role of a bone protein known as lipocalin-2 (LCN-2) in the connection between periodontitis and type 2 diabetes (T2D). Periodontitis is a destructive gum and alveolar bone disease. LCN-2 levels are increased in both T2D and periodontitis. Using a mouse model of T2D with periodontitis, we examined how blocking LCN-2 function affected various aspects of these two diseases. We found that this inhibition led to significant improvements. First, it reduced alveolar bone loss and preserved bone structure by decreasing local inflammation and bone resorption. Second, it improved glucose and lipid metabolism, leading to better blood-sugar control and decreased insulin resistance. Blocking the functions of LCN-2 also decreased systemic inflammation throughout the body and strengthened bone integrity. Overall, our results suggest that LCN-2 plays a crucial role in the periodontitis associated with T2D. By inhibiting LCN-2 function, we were able to improve pancreatic function, improve glucose metabolism, reduce inflammation, and enhance bone health. Targeting LCN-2 could be a promising strategy for the harmful effects of T2D and periodontitis.

Effect of chronic alcohol consumption on oral microbiota in rats with periodontitis

Background

The imbalance of oral microbiota can contribute to various oral disorders and potentially impact general health. Chronic alcohol consumption beyond a certain threshold has been implicated in influencing both the onset and progression of periodontitis. However, the mechanism by which chronic alcohol consumption affects periodontitis and its association with changes in the oral microbial community remains unclear.

Objective

This study used 16S rRNA gene amplicon sequencing to examine the dynamic changes in the oral microbial community of rats with periodontitis influenced by chronic alcohol consumption.

Methods

Twenty-four male Wistar rats were randomly allocated to either a periodontitis (P) or periodontitis + alcohol (PA) group. The PA group had unrestricted access to alcohol for 10 weeks, while the P group had access to water only. Four weeks later, both groups developed periodontitis. After 10 weeks, serum levels of alanine aminotransferase and aspartate aminotransferase in the rats' serum were measured. The oral swabs were obtained from rats, and 16S rRNA gene sequencing was conducted. Alveolar bone status was assessed using hematoxylin and eosin staining and micro-computed tomography.

Results

Rats in the PA group exhibited more severe periodontal tissue damage compared to those in the periodontitis group. Although oral microbial diversity remained stable, the relative abundance of certain microbial communities differed significantly between the two groups. Actinobacteriota and Desulfobacterota were more prevalent at the phylum level in the PA group. At the genus level, Cutibacterium, Tissierella, Romboutsia, Actinomyces, Lawsonella, Anaerococcus, and Clostridium_sensu_stricto_1 were significantly more abundant in the PA group, while Haemophilus was significantly less abundant. Additionally, functional prediction using Tax4Fun revealed a significant enrichment of carbohydrate metabolism in the PA group.

Conclusion

Chronic alcohol consumption exacerbated periodontitis in rats and influenced the composition and functional characteristics of their oral microbiota, as indicated by 16S rRNA gene sequencing results. These microbial alterations may contribute to the exacerbation of periodontitis in rats due to chronic alcohol consumption.

A comparison of oral bacteriome isolated from periodontal pockets of participants with or without diabetes mellitus in Uganda: a case control study

OBJECTIVE

Diabetes mellitus predisposes patients to increased incidence and severe forms of periodontal disease. Currently, information on the bacterial diversity of patients with diabetes mellitus and periodontitis in Uganda is scanty. This study set out to describe the bacteria associated with periodontitis in patients with diabetes mellitus in Uganda, as part of a larger study describing the association between periodontal disease and diabetes mellitus.

RESULTS

This was a case control involving 45 samples of gingival crevicular fluid collected from participants with periodontitis, the cases being 26 participants with diabetes mellitus and controls 19 participants without diabetes mellitus. Sequencing using the 16s Oxford nanopore long read protocol was followed by a bioinformatics analysis pipeline for alpha and beta diversity indices in the two groups. Multivariate tests were done to determine the differences in the bacterial composition in the two groups. Of the 739 Operational Taxonomic Units and 500 phyla identified, 37.9% (280/739) were from participants with diabetes mellitus. Analysis of beta diversity revealed a dissimilarity between the two study groups (CAP score = 0) with a significant association noted between periodontitis and the subgingival bacteria (P = 0.001). Diabetes mellitus reduced the quantity and altered the composition of the subgingival microbiome in the study participants.

Does "all disease begin in the gut"? The gut-organ cross talk in the microbiome

The human microbiome, a diverse ecosystem of microorganisms within the body, plays pivotal roles in health and disease. This review explores site-specific microbiomes, their role in maintaining health, and strategies for their upkeep, focusing on oral, lung, vaginal, skin, and gut microbiota, and their systemic connections. Understanding the intricate relationships between these microbial communities is crucial for unraveling mechanisms underlying human health. Recent research highlights bidirectional communication between the gut and distant microbiome sites, influencing immune function, metabolism, and disease susceptibility. Alterations in one microbiome can impact others, emphasizing their interconnectedness and collective influence on human physiology. The therapeutic potential of gut microbiota in modulating distant microbiomes offers promising avenues for interventions targeting various disorders. Through interdisciplinary collaboration and technological advancements, we can harness the power of the microbiome to revolutionize healthcare, emphasizing microbiome-centric approaches to promote holistic well-being while identifying areas for future research.

Impact of HbA1c control and type 2 diabetes mellitus exposure on the oral microbiome profile in the elderly population

Objective

To investigate the associations of the oral microbiome status with diabetes characteristics in elderly patients with type 2 diabetes mellitus.

Methods

A questionnaire was used to assess age, sex, smoking status, drinking status, flossing frequency, T2DM duration and complications, and a blood test was used to determine the glycated haemoglobin (HbA1c) level. Sequencing of the V3-V4 region of the 16S rRNA gene from saliva samples was used to analyze the oral microbiome.

Results

Differential analysis revealed that Streptococcus and Weissella were significantly enriched in the late-stage group, and Capnocytophaga was significantly enriched in the early-stage group. Correlation analysis revealed that diabetes duration was positively correlated with the abundance of Streptococcus (r= 0.369, p= 0.007) and negatively correlated with the abundance of Cardiobacterium (r= -0.337, p= 0.014), and the level of HbA1c was not significantly correlated with the oral microbiome. Network analysis suggested that the poor control group had a more complex microbial network than the control group, a pattern that was similar for diabetes duration. In addition, Streptococcus has a low correlation with other microorganisms.

Conclusion

In elderly individuals, Streptococcus emerges as a potential biomarker linked to diabetes, exhibiting elevated abundance in diabetic patients influenced by disease exposure and limited bacterial interactions.

Antibacterial and DNA-Based Hydrogels In Situ Block TNF-α to Promote Diabetic Alveolar Bone Rebuilding

Alveolar bone injury under diabetic conditions can severely impede many oral disease treatments. Rebuilding diabetic alveolar bone in clinics is currently challenging due to persistent infection and inflammatory response. Here, an antibacterial DNA-based hydrogel named Agantigel is developed by integrating silver nanoclusters (AgNCs) and tumor necrosis factor-alpha (TNF-α) antibody into DNA hydrogel to promote diabetic alveolar bone regeneration. Agantigel can effectively inhibit bacterial growth through AgNCs while exhibiting negligible cytotoxicity in vitro. The sustained release of TNF-α antibody from Agantigel effectively blocks TNF-α and promotes M2 polarization of macrophages, ultimately accelerating diabetic alveolar bone regeneration in vivo. After 21 days of treatment, Agantigel significantly accelerates the defect healing rate of diabetic alveolar bone up to 82.58 ± 8.58% and improves trabecular architectures compared to free TNF-α (42.52 ± 15.85%). The results imply that DNA hydrogels are potential bio-scaffolds helping the sustained release of multidrug for treating DABI or other oral diseases.

Oral Microbial and Molecular Cross Talk between SARS-CoV-2 and Diabetes Mellitus - A Mini Review

The oral microbiome has long been considered a measure of overall systemic health. It is often significantly altered in case of chronic inflammation or any other systemic infection. Therefore, a shift in oral microbiota and oral health is bound to be observed in diabetics infected with the coronavirus. The prognosis of COVID-19 in a diabetic individual is often worse than that in a healthy individual. The increased pathogenicity of coronavirus in diabetics is due to the peculiar ways in which it interacts with specific physiological mechanisms in a diabetic patient and vice versa. Diabetes Mellitus Type-II (DM -II) is one of the most frequently associated co-morbidities in a COVID-19 patient, and therefore it is even more pertinent that their interrelationship is understood. It is essential to recognize the above-mentioned interactions and consider their implications while treating susceptible patients. This article attempts to review and summarize the said vital interactions. Additionally, it attempts to guide and prepare oral health professionals on what to expect and how to treat diabetic patients in a future where coronavirus is, as unfortunate as it is, a regularity and not a rarity.

The Complicated Relationship of Short-Chain Fatty Acids and Oral Microbiome: A Narrative Review

The human oral microbiome has emerged as a focal point of research due to its profound implications for human health. The involvement of short-chain fatty acids in oral microbiome composition, oral health, and chronic inflammation is gaining increasing attention. In this narrative review, the results of early in vitro, in vivo, and pilot clinical studies and research projects are presented in order to define the boundaries of this new complicated issue. According to the results, the current research data are disputable and ambiguous. When investigating the role of SCFAs in human health and disease, it is crucial to distinguish between their local GI effects and the systemic influences. Locally, SCFAs are a part of normal oral microbiota metabolism, but the increased formation of SCFAs usually attribute to dysbiosis; excess SCFAs participate in the development of local oral diseases and in oral biota gut colonization and dysbiosis. On the other hand, a number of studies have established the positive impact of SCFAs on human health as a whole, including the reduction of chronic systemic inflammation, improvement of metabolic processes, and decrease of some types of cancer incidence. Thus, a complex and sophisticated approach with consideration of origin and localization for SCFA function assessment is demanded. Therefore, more research, especially clinical research, is needed to investigate the complicated relationship of SCFAs with health and disease and their potential role in prevention and treatment.

Patients with type 2 diabetes and severe periodontitis harbor a less pathogenic subgingival biofilm than normoglycemic individuals with severe periodontitis

BACKGROUND

Whether, and to what extent, diabetes mellitus (DM) can affect the subgingival biofilm composition remains controversial. Thus, the aim of this study was to compare the composition of the subgingival microbiota of non-diabetic and type 2 diabetic patients with periodontitis using 40 "biomarker bacterial species."

METHODS

Biofilm samples of shallow (probing depth [PD] and clinical attachment level [CAL] ≤3 mm without bleeding) and deep sites (PD and CAL ≥5 mm with bleeding) of patients with or without type 2 DM were evaluated for levels/proportions of 40 bacterial species by checkerboard DNA-DNA hybridization.

RESULTS

A total of 828 subgingival biofilm samples from 207 patients with periodontitis (118 normoglycemic and 89 with type 2 DM) were analyzed. The levels of most of the bacterial species evaluated were reduced in the diabetic compared with the normoglycemic group, both in shallow and in deep sites. The shallow and deep sites of patients with type 2 DM presented higher proportions of Actinomyces species, purple and green complexes, and lower proportions of red complex pathogens than those of normoglycemic patients (P < 0.05).

CONCLUSIONS

Patients with type 2 DM have a less dysbiotic subgingival microbial profile than normoglycemic patients, including lower levels/proportions of pathogens and higher levels/proportions of host-compatible species. Thus, type 2 diabetic patients seem to require less remarkable changes in biofilm composition than non-diabetic patients to develop the same pattern of periodontitis.

Impact of breastfeeding and other early-life factors on the development of the oral microbiome

The oral cavity is home to the second most diverse microbiome in the human body. This community contributes to both oral and systemic health. Acquisition and development of the oral microbiome is a dynamic process that occurs over early life; however, data regarding longitudinal assembly of the infant oral microbiome is scarce. While numerous factors have been associated with the composition of the infant oral microbiome, early feeding practices (breastfeeding and the introduction of solids) appear to be the strongest determinants of the infant oral microbiome. In the present review, we draw together data on the maternal, infant, and environmental factors linked to the composition of the infant oral microbiome, with a focus on early nutrition. Given evidence that breastfeeding powerfully shapes the infant oral microbiome, the review explores potential mechanisms through which human milk components, including microbes, metabolites, oligosaccharides, and antimicrobial proteins, may interact with and shape the infant oral microbiome. Infancy is a unique period for the oral microbiome. By enhancing our understanding of oral microbiome assembly in early life, we may better support both oral and systemic health throughout the lifespan.

Diabetes mellitus promotes susceptibility to periodontitis-novel insight into the molecular mechanisms

Diabetes mellitus is a main risk factor for periodontitis, but until now, the underlying molecular mechanisms remain unclear. Diabetes can increase the pathogenicity of the periodontal microbiota and the inflammatory/host immune response of the periodontium. Hyperglycemia induces reactive oxygen species (ROS) production and enhances oxidative stress (OS), exacerbating periodontal tissue destruction. Furthermore, the alveolar bone resorption damage and the epigenetic changes in periodontal tissue induced by diabetes may also contribute to periodontitis. We will review the latest clinical data on the evidence of diabetes promoting the susceptibility of periodontitis from epidemiological, molecular mechanistic, and potential therapeutic targets and discuss the possible molecular mechanistic targets, focusing in particular on novel data on inflammatory/host immune response and OS. Understanding the intertwined pathogenesis of diabetes mellitus and periodontitis can explain the cross-interference between endocrine metabolic and inflammatory diseases better, provide a theoretical basis for new systemic holistic treatment, and promote interprofessional collaboration between endocrine physicians and dentists.

Epigenetic changes underlie the association between diabetes mellitus and oral diseases

Patients with diabetes mellitus (DM) suffer from oral complications related to oral infections, periodontal diseases, and endodontic lesions. Emerging evidence has revealed the contribution of the epigenetic process as the underlying mechanism of DM complications. DNA methylation, histone modifications, and non-coding RNAs are epigenetic regulators that directly affect gene expression. The present review elaborated on the role of epigenetic dysregulation in the etiology of diabetes-related periodontal and endodontic diseases. The narrative review study was prepared using databases such as PubMed, Google Scholar, Science Direct, and Scopus. The formation of glycation products as a result of hyperglycemic condition increases oxidative stress, and elevates chronic inflammatory mediators that could in turn adversely change the cellular environment and alter the epigenetic status. This process contributes to the alteration of regulatory genes expression, leading to the development of diabetes-induced bone complications and impaired odontogenic capacity of pulp. Indeed, epigenetic mechanisms mediate the interaction between gene expression and DM cellular environment. Further investigations on epigenetic factors involved in DM oral complications may provide novel therapeutic targets.

Efficacy of nonsurgical periodontal therapy affecting salivary biomarkers in non-diabetic and type 2 diabetic periodontitis patients. An observational study

Objectives

To assess the effects of non-surgical periodontal therapy on salivary biomarkers in non-diabetic and type 2 diabetic periodontitis patients and to investigate if saliva may be used to monitor glucose levels in type 2 diabetes.

Material and methods

250 participants with chronic generalized periodontitis aged 35-70 years were divided into two groups: test group with type 2 diabetes (125 subjects with 64 males & 61 females) and control group with non-diabetic (125 subjects with 83 males & 42 females). Participants received non-surgical periodontal treatment. Pre-NSPT and 6-week post-NSPT saliva glucose, amylase, total protein, and C-reactive protein (CRP) levels were measured. Intergroup correlations were assessed using Karl Pearson's correlation coefficient and paired t-test.

Results

Non-surgical periodontal therapy significantly decreased CRP (p < 0.05) in diabetics and non-diabetics. CRP mean values changes from baseline 1.79 to post op 1.5 and baseline 1.5 to post-op 1.24 in males and females of test group, respectively. In control group males and females, mean values change from baseline 1.48 to post-op 1.42 and 1.499 to 1.40. Other parameters Glucose, amylase & total protein showed improvement in the level, but statistically non-significant (p > 0.05). Salivary glucose levels corresponded favorably with HbA1C levels.

Conclusion

In individuals with type 2 diabetes and non-diabetic generalized chronic periodontitis, non-surgical periodontal therapy may play a role in lowering the level of significant salivary biomarkers. Saliva can be utilized as a non-invasive approach for monitoring glucose levels in people with type 2 diabetes and chronic periodontitis.

A decade of progress: bibliometric analysis of trends and hotspots in oral microbiome research (2013-2022)

Background

Over the past decade, a plethora of studies have delved into the oral microbiome. Our objective was to evaluate the trends in oral microbiome research employing a quantitative approach.

Materials and methods

We extracted clinical studies on the oral microbiome published between 2013 and 2022 from the Web of Science database, yielding 3024 articles. The assembled literature was visually scrutinized using VOSviewer 1.6.18, Citespace 6.1.6, Pajek, Scimago Graphica, and other specialized software to assess authors, institutions, countries, journals, co-cited literature, keywords, genes, and diseases.

Results

Our analysis identified a total of 3024 articles. The volume and rate of annual publications steadily increased, with research interest in the oral microbiome progressively intensifying. The United States, China, and the UK contributed the highest number of publications. Growth rates of publications varied among countries over time. The Forsyth Institute emerged as the most collaborative institution, boasting the highest number of relevant papers (135) and securing the top rank, followed by Sichuan University and Harvard University. Paster Bruce J, Zhou Xuedong, and He Xuesong were pioneers in the field of oral microbiome research. This analysis demonstrates that the homeostatic balance of the oral microbiome, advanced microbial sequencing technology, connections with gut microbiota, and tumorigenesis, including oral cancer, have become emerging topics in the oral microbiome field.

Conclusions

This study delineated a comprehensive landscape of hotspots and frontiers in oral microbiome research, thus facilitating the identification of interdisciplinary advancements. We sincerely hope that our bibliometric analysis will enable researchers to leverage the oral microbiome to ultimately improve human oral health.

[Advances in Research on the Mechanism of Association Between Periodontitis and Diabetes Mellitus]

Periodontitis and diabetes mellitus are both chronic diseases with a rather high prevalence and they are closely associated with each other. On one hand, diabetes mellitus poses as a risk factor for periodontitis. On the other hand, periodontitis has a negative impact on glucose control in diabetic patients. The two-way relationship has aroused a lot of research interest in recent years. Herein, approaching the issue by looking at the effect of periodontitis on diabetes, we summarized the mechanism of the traditional periodontal pocket-blood circulation pathway and reviewed the role of the oral-gut axis in the mechanism, which has been proposed in recent years. In addition, regarding the impact of diabetes on periodontitis, we summarized new findings concerning changes in oral microbiota, abnormal levels of cytokines and adipokines, oxidative stress, unbalanced osteogenic and osteoclastic activities, and the accumulation of advanced glycation end-products. We hope this paper will be helpful for further studies on the mechanism of association between periodontitis and diabetes.

Elevated dietary carbohydrate and glycemic intake associate with an altered oral microbial ecosystem in two large U.S. cohorts

The human oral microbiome is associated with chronic diseases including cancer. However, our understanding of its relationship with diet is limited. We assessed the associations between carbohydrate and glycemic index (GI) with oral microbiome composition in 834 non-diabetic subjects from the NCI-PLCO and ACS-CPSII cohorts. The oral microbiome was characterized using 16Sv3-4 rRNA-sequencing from oral mouthwash samples. Daily carbohydrate and GI were assessed from food frequency questionnaires. We used linear regression, permutational MANOVA, and negative binomial Generalized Linear Models (GLM) to test associations of diet with α- and β-diversity and taxon abundance (adjusting for age, sex, cohort, BMI, smoking, caloric intake, and alcohol). A q-value (FDR-adjusted P-value) of <0.05 was considered significant. Oral bacterial α-diversity trended higher in participants in the highest quintiles of carbohydrate intake, with marginally increased richness and Shannon diversity (p-trend=0.06 and 0.07). Greater carbohydrate intake was associated with greater abundance of class Fusobacteriia (q=0.02) and genus Leptotrichia (q=0.01) and with lesser abundance of an Actinomyces OTU (q=4.7E-04). Higher GI was significantly related to greater abundance of genus Gemella (q=0.001). This large, nationwide study provides evidence that diets high in carbohydrates and GI may influence the oral microbiome.