Influential factors of saliva microbiota composition

The Healthy Oral Microbiome: A Changing Ecosystem throughout the Human Lifespan

Microorganisms have co-evolved with a variety of plants and animals, developing complex symbiotic relationships with their hosts and the environment. The diversity of symbionts acquired over time help their hosts to adapt, survive, and evolve more rapidly and efficiently, improving fitness across the lifespan. Understanding these synergistic relationships between humans and their endogenous microbiota may provide valuable information on human physiology and on potential mechanisms associated with the onset of diseases. This review summarizes current data on the composition and functionality of the predominant taxa of the healthy oral microbiome across different ages and habitats within the oral cavity, critically pointing out the inconsistency of methodologies for microbiological analysis and what still needs to be validated. We discuss how early acquisition and establishment of the oral microbiome are influenced by factors such as delivery type and feeding practices, and how adolescence marks a phase of significant shifts in the oral taxa due to hormonal and behavioral transitions. During adulthood, the healthy oral microbiome may acquire multistable signatures, shaped by genetic and environmental factors, while minor changes in core microorganisms are observed in the healthy aging populations. Overall, evidence shows that the oral microbiome is a complex ecosystem, continuously modulated by several factors, since its early acquisition through adulthood and into old age. Fluctuations do happen, but a resilient core community will persist over time in most humans to maintain homeostasis. Future challenges of microbiome research will rely on our ability to define multiple age-related healthy oral microbiomes across populations, so that oral dysbiosis can be detected and managed in advance. In this context, standardization of data acquisition and analysis, as well as improvements in multidisciplinary clinical diagnosis of oral health, must be pursued for a better comprehension of the balanced host-microbiome interaction.

Oral Mycobiome Alterations in Postmenopausal Women: Links to Inflammation, Xerostomia, and Systemic Health

The oral mycobiome plays a critical role in maintaining oral and systemic health, with its composition and function influenced by various physiological and environmental factors. This descriptive review explores the changes in the oral mycobiome among postmenopausal women, examining how aging and associated inflammatory processes contribute to these alterations. These changes are linked to an increased prevalence of xerostomia, oral dysbiosis, and inflammation, which can negatively impact both oral and systemic health. We discuss the impact of hormonal fluctuations and immune senescence on fungal diversity and abundance, highlighting key species implicated in oral and systemic diseases. The review also examines the role of systemic conditions and medications, which are common in postmenopausal women, in further exacerbating oral mycobiome alterations. Lastly, it highlights the need for future research to better understand these interactions and develop targeted therapeutic strategies. The current literature indicates a significant association between menopausal status, age-related mycobiome shifts, and increased inflammatory responses, suggesting potential pathways for intervention.

Human Salivary Microbiota Diversity According to Ethnicity, Sex, TRPV1 Variants and Sensitivity to Capsaicin

The salivary microbiota of Italian and sub-Saharan African individuals was investigated using Nanopore sequencing technology (ONT: Oxford Nanopore Technologies). We detected variations in community composition in relation to endogenous (ethnicity, sex, and diplotypic variants of the TRPV1 gene) and exogenous (sensitivity to capsaicin) factors. The results showed that Prevotella, Haemophilus, Neisseria, Streptococcus, Veillonella, and Rothia are the most abundant genera, in accordance with the literature. However, alpha diversity and frequency spectra differed significantly between DNA pools. The microbiota in African, male TRPV1 bb/ab diplotype and capsaicin low-sensitive DNA pools was more diverse than Italian, female TRPV1 aa diplotype and capsaicin high-sensitive DNA pools. Relative abundance differed at the phylum, genus, and species level.

A Rose by Any Other Name: The Long Intricate History of Localized Aggressive Periodontitis

This review addresses the recent World Workshop Consensus Conference (WWCC) decision to eliminate Localized Aggressive Periodontitis (LAgP) in young adults as a distinct form of periodontitis. A "Consensus" implies widespread, if not unanimous, agreement among participants. However, a significant number of attendees were opposed to the elimination of the LAgP classification. The substantial evidence supporting a unique diagnosis for LAgP includes the (1) incisor/molar pattern of disease, (2) young age of onset, (3) rapid progression of attachment and bone loss, (4) familial aggregation across multiple generations, and (5) defined consortium of microbiological risk factors including Aggregatibacter actinomycetemcomitans. Distinctive clinical signs and symptoms of LAgP are presented, and the microbial subgingival consortia that precede the onset of signs and symptoms are described. Using Bradford-Hill guidelines to assess causation, well-defined longitudinal studies support the unique microbial consortia, including A. actinomycetemcomitans as causative for LAgP. To determine the effects of the WWCC elimination of LAgP on research, we searched three publication databases and discovered a clear decrease in the number of new publications addressing LAgP since the new WWCC classification. The negative effects of the WWCC guidelines on both diagnosis and treatment success are presented. For example, due to the localized nature of LAgP, the practice of averaging mean pocket depth reduction or attachment gain across all teeth masks major changes in disease recovery at high-risk tooth sites. Reinstating LAgP as a distinct disease entity is proposed, and an alternative or additional way of measuring treatment success is recommended based on an assessment of the extension of the time to relapse of subgingival re-infection. The consequences of the translocation of oral microbes to distant anatomical sites due to ignoring relapse frequency are also discussed. Additional questions and future directions are also presented.

Effect of Morchella esculenta polysaccharides on the rectal microbiota of mice challenged with lipopolysaccharides

Introduction

Intestinal dysfunction poses a severe problem by preventing the digestion and absorption of nutrients. The gut, being the most vital organ for these processes, plays a crucial role in ensuring our body receives the nutrients it needs. We explored the mitigating effect of Morchella esculenta polysaccharides (MEP) on intestinal injury induced by lipopolysaccharides (LPS) through the modulation of intestinal flora.

Methods

For this purpose, Kunming mice (KM) were divided into three groups, namely, PC, PM, and PY. Group PY was treated with MEP, while groups PM and PY were induced with LPS.

Results

The results showed that weight loss in the PM group was significantly greater than that in the PY group (P < 0.05), and the organ indexes of the lung and spleen in the PM group were significantly higher than those in the PC (P < 0.01) and PY (P < 0.05) groups. LPS caused severe injuries in KM mice in the PM group, characterized by broken villi. However, MEP treatment could alleviate this damage in the PY group, resulting in relatively intact villi. The serum analysis showed that tumor necrosis factor alpha (TNF-ɑ) (P < 0.01), interleukin 6 (IL-6) (P < 0.01), and 3,4-methylenedioxyamphetamine (MDA) (P < 0.05) levels were significantly higher in the PM group, while IL-10 (P < 0.001), superoxide dismutase (SOD) (P < 0.01) and glutathione peroxidase (GSH-Px) (P < 0.01) were significantly lower in that group. Interestingly, supplementation with MEP could lower the levels of TNF-ɑ, IL-10, IL-6, MDA while increasing the levels of superoxide dismutase (SOD) (P < 0.01) and GSH-Px. The gut microbiota analysis yielded 630,323 raw reads and 554,062 clean reads, identifying 3,390 amplicon sequencing variants (ASVs). One phylum and five genera were notably different among animal groups, including Escherichia_Shigella, Limosilactobacillus, unclassified_Geminicoccaceae, unclassified_Rhodobacteraceae, and Parabacteroides (P. distasonis).

Discussion

In conclusion, we found that MEP could mitigate the intestinal damage caused by LPS by modulating the inflammatory response, oxidative resistance, and intestinal flora of KM mice. Our results may provide insights into novel treatment options for intestine-related diseases.

A multicomponent personalized prevention program in the primary care setting: a randomized clinical trial in older people with noncommunicable chronic diseases (Primacare_P3 study)

BACKGROUND

Multicomponent interventions based on a comprehensive geriatric assessment (CGA) could promote active aging and improve health status in older people with Noncommunicable Chronic Diseases (NCDs), but conflicting evidences are available.

AIM

To evaluate the efficacy of a CGA-based multicomponent personalized preventive program (PPP) in reducing unplanned hospitalization rates during 12-month follow-up in community-dwelling older people with NCDs.

MATERIALS AND METHODS

In this randomized clinical trial (RCT), 1216 older adults recruited by 33 general practitioners (GPs) will be randomly allocated to intervention group (IG) or usual care control group (CG). The IG will receive a multicomponent PPP developed on the findings of the CGA-based Multidimensional Prognostic Index short-form (Brief-MPI), including structured interventions to improve functional, physical, cognitive, and nutritional status, to monitor NCDs and vaccinations, and to prevent social isolation. Participants in the CG will receive usual care. Brief-MPI, resilience, and health-related quality of life will be assessed after 6 and 12 months. Moreover, saliva samples will be collected at baseline in IG to measure biomarkers of oxidative stress, inflammatory cytokines, and oral microbiome.

EXPECTED RESULTS

The CGA-based PPP might reduce unplanned hospitalization rates and potentially institutionalization rates, emergency department (ED) and unplanned GP visits, and mortality. Further outcomes explored in the IG will be the adherence to PPP, resilience, health-related quality of life, and multidimensional frailty as assessed by the Brief-MPI.

CONCLUSIONS

Results will suggest whether the CGA-based multicomponent PPP is able to improve specific outcomes in a primary care setting.

TRIAL REGISTRATION

ClinicalTrials.gov; identifier: NCT06224556 ; Registered January 25, 2024.

Oral microbial signatures associated with age and frailty in Canadian adults

This study aimed to assess the association between the oral microbiome, age, and frailty. Data and saliva samples were obtained from male and female participants aged 35-70 years (n = 1357). Saliva samples were analysed by 16S rRNA gene sequencing and differences in microbial diversity and community compositions were examined in relation to chronological age and the frailty index (FI). Most alpha diversity measures (Richness, Shannon Diversity, Faith's Phylogenetic Diversity) showed an inverse association with frailty, whereas a positive association was observed with age and Shannon Diversity and Evenness. A further sex-stratified analysis revealed differences in measures of microbial diversity and composition. Multiple genera were detected as significantly differentially abundant with increasing frailty and age by at least two methods. With age, the relative abundance of Veillonella was reduced in both males and females, whereas increases in Corynebacterium appeared specific to males and Aggregatibacter, Fusobacterium, Neisseria, Stomatobaculum, and Porphyromonas specific to females. Beta diversity was significantly associated with multiple mental health components of the FI. This study shows age and frailty are differentially associated with measures of microbial diversity and composition, suggesting the oral microbiome may be a useful indicator of increased risk of frailty or a potential target for improving health in ageing adults.

Altered salivary microbiota profile in patients with abdominal aortic aneurysm

Evidence suggests that the DNA of oral pathogens is detectable in the dilated aortic tissue of abdominal aortic aneurysm (AAA), one of the most fatal cardiovascular diseases. However, the association between oral microbial homeostasis and aneurysm formation remains largely unknown. In this study, a cohort of individuals, including 53 AAA patients and 30 control participants (CTL), was recruited for salivary microbiota investigation by 16S rRNA gene sequencing and bioinformatics analysis. Salivary microbial diversity was decreased in AAA compared with CTL, and the microbial structures were significantly separated between the two groups. Additionally, significant taxonomic and functional changes in the salivary microbiota of AAA participants were observed. The genera Streptococcus and Gemella were remarkably enriched, while Selenomonas, Leptotrichia, Lautropia and Corynebacterium were significantly depleted in AAA. Co-occurrence network analysis showed decreased potential interactions among the differentially abundant microbial genera in AAA. A machine-learning model predicted AAA using the combination of 5 genera and 14 differentially enriched functional pathways, which could distinguish AAA from CTL with an area under the receiver-operating curve of 90.3 %. Finally, 16 genera were found to be significantly positively correlated with the morphological parameters of AAA. Our study is the first to show that AAA patients exhibit oral microbial dysbiosis, which has high predictive power for AAA, and the over-representation of specific salivary bacteria may be associated with AAA disease progression. Further studies are needed to better understand the function of putative oral bacteria in the etiopathogenesis of AAA.

Importance

Host microbial dysbiosis has recently been linked to AAA as a possible etiology. To our knowledge, studies of the oral microbiota and aneurysms remain scarce, although previous studies have indicated that the DNA of some oral pathogens is detectable in aneurysms by PCR method. We take this field one step further by investigating the oral microbiota composition of AAA patients against control participants via high-throughput sequencing technologies and unveiling the potential microbial biomarker associated with AAA formation. Our study will provide new insights into AAA etiology, treatment and prevention from a microecological perspective and highlight the effects of oral microbiota on vascular health.

Hyposalivation but not Sjögren's syndrome associated with microbial dysbiosis in women

Background

Saliva modulates the environment of the oral biofilm through pH buffer, microbial attachment to host surfaces, and nutritional source. The ecology of stress occurs when a physical factor adversely impacts an ecosystem or its biotic components. Therefore, reduced salivary flow can affect oral-host balance. The leading causes of hyposalivation include disease-associated Sjögren's syndrome (SS) and menopausal women as aging-associated. However, little is known about the oral microbiome integrated with sex hormones in hyposalivation. This study aimed to characterize the hyposalivation microbiome caused by aging or disease affecting the salivary glands in women.

Methods

We included 50 women older than 40 years of age in any menopausal phase. We collected stimulated saliva from 25 women diagnosed with SS (SS) and 25 without SS (non-SS). The bacterial profile of the patients was obtained by 16S rRNA sequencing. Bioinformatics analysis used machine learning to analyze the cohort's signs, symptoms, and bacterial profile. Salivary estradiol as a sex hormone variation level was determined.

Results

We obtained that 79% of the SS group, and 52% of the non-SS group had hyposalivation. We found a negatively correlated Prevotella-age and Rothia-estradiol in the SS group. Highlight, we found that the cause of the hyposalivation in the study did not explain differences in microbial diversity comparing non-SS and SS groups. Therefore, microbial communities found in hyposalivation but not related to systemic conditions suggest that changes in the oral environment might underpin host-microbial balance.

Conclusion

The salivary microbiome was similar in women with and without SS. However, hyposalivation showed two distinctive clusters associated with the bacterial population profiles. Our study suggests that local ecological disturbances could drive the change in the microbiome.

Unexpected lower level of oral periodontal pathogens in patients with high numbers of systemic diseases

Background

Periodontal disease is associated with systemic conditions such as diabetes, arthritis, and cardiovascular disease, all diseases with large inflammatory components. Some, but not all, reports show periopathogens Porphyromonas gingivialis and Tannerella forsythia at higher levels orally in people with one of these chronic diseases and in people with more severe cases. These oral pathogens are thought to be positively associated with systemic inflammatory diseases through induction of oral inflammation that works to distort systemic inflammation or by directly inducing inflammation at distal sites in the body. This study aimed to determine if, among patients with severe periodontal disease, those with multi-morbidity (or many chronic diseases) showed higher levels of periodontal pathogens.

Methods

A total of 201 adult subjects, including 84 with severe periodontal disease were recruited between 1/2017 and 6/2019 at a city dental clinic. Electronic charts supplied self-reported diseases and conditions which informed a morbidity index based on the number of chronic diseases and conditions present. Salivary composition was determined by 16S rRNA gene sequencing.

Results

As expected, patients with severe periodontal disease showed higher levels of periodontal pathogens in their saliva. Also, those with severe periodontal disease showed higher levels of multiple chronic diseases (multimorbidity). An examination of the 84 patients with severe periodontal disease revealed some subjects despite being of advanced age were free or nearly free of systemic disease. Surprisingly, the salivary microbiota of the least healthy of these 84 subjects, defined here as those with maximal multimorbidity, showed significantly lower relative numbers of periodontal pathogens, including Porphyromonas gingivalis and Tannerella Forsythia, after controlling for active caries, tobacco usage, age, and gender. Analysis of a control group with none to moderate periodontal disease revealed no association of multimorbidity or numbers of medications used and specific oral bacteria, indicating the importance of severe periodontal disease as a variable of interest.

Conclusion

The hypothesis that periodontal disease patients with higher levels of multimorbidity would have higher levels of oral periodontal pathogens is false. Multimorbidity is associated with a reduced relative number of periodontal pathogens Porphyromonas gingivalis and Tannerella forsythia.