Oral microbiota and periodontitis severity among Hispanic adults

Oral microbiome diversity and diet quality in relation to mortality

AIM

To examine the independent and joint associations of oral microbiome diversity and diet quality with risks of all-cause and cause-specific mortality.

MATERIALS AND METHODS

We included 7,055 eligible adults from the U.S. National Health and Nutrition Examination Survey (NHANES). Oral microbiome diversity was measured with α-diversity, including the Simpson Index, observed amplicon sequence variants (ASVs), Faith's phylogenetic diversity, and Shannon-Weiner index. Dietary quality was assessed using the Healthy Eating Index-2015 (HEI-2015). Cox proportional hazard models were used to assess the corresponding associations.

RESULTS

During a mean follow-up of 9.0 years, we documented 382 all-cause deaths. We observed independent associations of oral microbiome diversity indices and dietary quality with all-cause mortality (hazard ratio [HR] = 0.63; 95% confidence interval [CI]: 0.49-0.82 for observed ASVs; HR = 0.68, 95% CI: 0.52-0.89 for HEI-2015). Jointly, participants with the highest tertiles of both oral microbiome diversity (in Simpson index) and HEI-2015 had the lowest hazard of mortality (HR = 0.37, 95% CI: 0.23-0.60). In addition, higher oral microbiome diversity was associated with lower risks of deaths from cardiometabolic disease and cancer.

CONCLUSIONS

Higher oral microbiome α-diversity and diet quality were independently associated with lower risk of mortality.

Probing the oral-brain connection: oral microbiome patterns in a large community cohort with anxiety, depression, and trauma symptoms, and periodontal outcomes

The role of the oral microbiome in mental health has recently been appreciated within the proposed oral-brain axis. This study examined the structure and composition of the salivary microbiome in a large-scale population-based cohort of individuals reporting mental health symptoms (n = 306) compared to mentally healthy controls (n = 164) using 16S rRNA sequencing. Mental health symptoms were evaluated using validated questionnaires and included depression, anxiety, and posttraumatic stress disorder (PTSD), with accompanying periodontal outcomes. Participants also indicated current or previous diagnoses of anxiety, depression, periodontitis, and gingivitis. Mental and periodontal health variables influenced the overall composition of the oral microbiome. PTSD symptoms correlated with a lower clr-transformed relative abundance of Haemophilus sputorum and a higher clr-transformed relative abundance of Prevotella histicola. The clr-transformed relative abundance of P. histicola was also positively associated with depressive scores and negatively associated with psychological quality of life. Anxiety disorder diagnosis was associated with a lower clr-transformed relative abundance of Neisseria elongate and a higher clr-transformed relative abundance of Oribacterium asaccharolyticum. A higher clr-transformed relative abundance of Shuttleworthia and lower clr-transformed relative abundance of Capnocytophaga were evident in those who reported a clinical periodontitis diagnosis. Higher Eggerthia and lower Haemophilus parainfluenzae clr-transformed relative abundances were associated with reported clinical periodontitis diagnoses and psychotherapeutic efficacy. Functional prediction analysis revealed a potential role for tryptophan metabolism/degradation in the oral-brain axis, which was confirmed by lower plasma serotonin levels across symptomatic groups. This study sheds light on the intricate interplay between oral microbiota, periodontal and mental health outcomes, and a potential role for tryptophan metabolism in the proposed oral-brain axis, emphasizing the need for further exploration to pave the way for novel therapeutic interventions and predicting therapeutic response.

Supragingival Plaque Microbiomes in a Diverse South Florida Population

Trillions of microbes comprise the human oral cavity, collectively acting as another bodily organ. Although research is several decades into the field, there is no consensus on how oral microbiomes differ in underrepresented groups such as Hispanic, Black, and Asian populations living in the United States. Here, using 16S ribosomal RNA sequencing, we examine the bacterial ecology of supragingival plaque from four quadrants of the mouth along with a tongue swab from 26 healthy volunteers from South Florida (131 total sequences after filtering). As an area known to be a unique amalgamation of diverse cultures from across the globe, South Florida allows us to address the question of how supragingival plaque microbes differ across ethnic groups, thus potentially impacting treatment regiments related to oral issues. We assess overall phylogenetic abundance, alpha and beta diversity, and linear discriminate analysis of participants based on sex, ethnicity, sampling location in the mouth, and gingival health. Within this cohort, we find the presence of common phyla such as Firmicutes and common genera such as Streptococcus. Additionally, we find significant differences across sampling locations, sex, and gingival health. This research stresses the need for the continued incorporation of diverse populations within human oral microbiome studies.

Development of a multiplex PCR assay and quantification of microbial markers by ddPCR for identification of saliva and vaginal fluid

The identification of biological fluids at crime scenes contributes to crime scene reconstruction and provides investigative leads. Traditional methods for body fluid identification are limited in terms of sensitivity and are mostly presumptive. Emerging methods based on mRNA and DNA methylation require high quality template source. An exploitable characteristic of body fluids is their distinct microbial profiles allowing for the discrimination of body fluids based on microbiome content. Microbial DNA is highly abundant within the body, robust and stable and can persist in the environment long after human DNA has degraded. 16S rRNA sequencing is the gold standard for microbial analysis; however, NGS is costly, and requires intricate workflows and interpretation. Also, species level resolution is not always achievable. Based on the current challenges, the first objective of this study was to develop a multiplex conventional PCR assay to identify vaginal fluid and saliva by targeting species-specific 16S rRNA microbial markers. The second objective was to employ droplet digital PCR (ddPCR) as a novel approach to quantify bacterial species alone and in a mixture of body fluids. Lactobacillus crispatus and Streptococcus salivarius were selected because of high abundance within vaginal fluid and saliva respectively. While Fusobacterium nucleatum and Gardnerella vaginalis, though present in healthy humans, are also frequently found in oral and vaginal infections, respectively. The multiplex PCR assay detected L. crispatus and G. vaginalis in vaginal fluid while F. nucleatum and S. salivarius was detected in saliva. Multiplex PCR detected F. nucleatum, S. salivarius and L. crispatus in mixed body fluid samples while, G. vaginalis was undetected in mixtures containing vaginal fluid. For samples exposed at room temperature for 65 days, L. crispatus and G. vaginalis were detected in vaginal swabs while only S. salivarius was detected in saliva swabs. The limit of detection was 0.06 copies/µl for F. nucleatum (2.5 ×10-9 ng/µl) and S. salivarius (2.5 ×10-6 ng/µl). L. crispatus and G. vaginalis had detection limits of 0.16 copies/µl (2.5 ×10-4 ng/µl) and 0.48 copies/µl (2.5 ×10-7 ng/µl). All 4 bacterial species were detected in mixtures and aged samples by ddPCR. No significant differences were observed in quantity of bacterial markers in saliva and vaginal fluid. The present research reports for the first time the combination of the above four bacterial markers for the detection of saliva and vaginal fluid and highlights the sensitivity of ddPCR for bacterial quantification in pure and mixed body fluids.

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.

Alterations in the Salivary Microbiome and Metabolism in Patients With Carotid Atherosclerosis from Rural Northeast China

BACKGROUND

Periodontitis and atherosclerosis are both chronic inflammatory diseases with a high prevalence. Increasing evidence supports the independent association between severe periodontitis and atherosclerotic cardiovascular disease, in which oral microorganisms may play an important role. We aimed to evaluate the characteristic changes of salivary microbiome and metabolome in patients with carotid atherosclerosis (CAS) and periodontitis.

METHODS AND RESULTS

The subjects were obtained from a cross-sectional study that included 1933 participants aged 40 years or older from rural northeast China. The study enrolled 48 subjects with CAS and 48 controls without CAS matched by sex, age, body mass index, and prevalence of hypertension, diabetes, and dyslipidemia. We performed full-length 16S rDNA gene sequencing and untargeted metabolomics of saliva samples from 96 subjects. We found that CAS was closely associated with an increased abundance of Streptococcus, Lactobacillus, and Cutibacterium. Furthermore, patients with CAS had higher prevalence of severe periodontitis than the control group. Notably, periodontal pathogens such as Tannerella and Anaeroglobus were not only associated with periodontitis but also enriched in patients with CAS, whereas periodontal health-associated Neisseria was more abundant in those without CAS. We also identified 2 lipid metabolism pathways, including glycerophospholipid and sphingolipid metabolism, as associated with CAS. The levels of trimethylamine N-oxide and inflammatory mediator leukotriene D4 were significantly higher in patients with CAS, whereas the levels of carnosine were significantly lower, than those in controls. Additionally, serum levels of inflammatory marker high-sensitivity C-reactive protein were significantly increased in CAS and positively correlated with the abundance of Anaeroglobus and leukotriene D4 in saliva.

CONCLUSIONS

Our study suggests that characteristic changes in salivary microbiota and metabolites are closely related to CAS, and periodontitis and associated microorganisms may be involved in the initiation and progression of CAS.

Shifts in the gut microbiota of sea urchin Diadema antillarum associated with the 2022 disease outbreak

Introduction

In recent decades, Caribbean coral reefs have lost many vital marine species due to diseases. The well-documented mass mortality event of the long-spined black sea urchin Diadema antillarum in the early 1980s stands out among these collapses. This die-off killed over 90% of D. antillarum changing the reefscape from coral to algal-dominated. Nearly 40 years later, D. antillarum populations have yet to recover. In early 2022, a new mortality event of D. antillarum was reported along the Caribbean, including Puerto Rico.

Methods

This study identifies the gut microbiota changes associated with the D. antillarum during this mortality event. It contrasts them with the bacterial composition of gut samples from healthy individuals collected in 2019 by using 16S rRNA sequencing analyses.

Results

Notably, the die-off group's core microbiome resembled bacteria commonly found in the human skin and gut, suggesting potential anthropogenic contamination and wastewater pollution as contributing factors to the 2022 dysbiosis. The animals collected in 2022, especially those with signs of disease, lacked keystone taxa normally found in Diadema including Photobacterium and Propionigenium.

Discussion

The association between human microbes and disease stages in the long-spined urchin D. antillarum, especially in relation to anthropogenic contamination, highlights a complex interplay between environmental stressors and marine health. While these microbes might not be the direct cause of death in this species of sea urchins, their presence and proliferation can indicate underlying issues, such as immune depletion due to pollution, habitat destruction, or climate change, that ultimately compromise the health of these marine organisms.

Differential Patterns of Gut and Oral Microbiomes in Hispanic Individuals with Cognitive Impairment

Alzheimer's disease and related dementias (ADRD) have been associated with alterations in both oral and gut microbiomes. While extensive research has focused on the role of gut dysbiosis in ADRD, the contribution of the oral microbiome remains relatively understudied. Furthermore, the potential synergistic interactions between oral and gut microbiomes in ADRD pathology are largely unexplored. This study aims to evaluate distinct patterns and potential synergistic effects of oral and gut microbiomes in a cohort of predominantly Hispanic individuals with cognitive impairment (CI) and without cognitive impairment (NC). We conducted 16S rRNA gene sequencing on stool and saliva samples from 32 participants (17 CI, 15 NC; 62.5% female, mean age = 70.4 ± 6.2 years) recruited in San Antonio, Texas, USA. Correlation analysis through MaAslin2 assessed the relationship between participants' clinical measurements (e.g., fasting glucose and blood cholesterol) and their gut and saliva microbial contents. Differential abundance analysis evaluated taxa with significant differences between CI and NC groups, and alpha and beta diversity metrics assessed within-sample and group compositional differences. Our analyses revealed no significant differences between NC and CI groups in fasting glucose or blood cholesterol levels. However, a clear association was observed between gut microbiome composition and levels of fasting glucose and blood cholesterol. While alpha and beta diversity metrics showed no significant differences between CI and NC groups, differential abundance analysis revealed an increased presence of oral genera such as Dialister , Fretibacterium , and Mycoplasma in CI participants. Conversely, CI individuals exhibited a decreased abundance of gut genera, including Shuttleworthia , Holdemania , and Subdoligranulum , which are known for their anti-inflammatory properties. No evidence was found for synergistic contributions between oral and gut microbiomes in the context of ADRD. Our findings suggest that similar to the gut microbiome, the oral microbiome undergoes significant modifications as individuals transition from NC to CI. Notably, the identified oral microbes have been previously associated with periodontal diseases and gingivitis. These results underscore the necessity for further investigations with larger sample sizes to validate our findings and elucidate the complex interplay between oral and gut microbiomes in ADRD pathogenesis.

A Cohort Study of the Influence of the 12-Component Modified Japanese Diet Index on Oral and Gut Microbiota in the Japanese General Population

The Japanese diet is a healthy dietary pattern, and the oral or gut microbiota have been identified as the main factors underlying the beneficial effects of the Japanese diet. However, epidemiological studies on Japanese dietary patterns calculated from daily eating habits in the general population yielded inconsistent findings. This study aimed to determine the association between the 12-component modified Japanese Diet Index (mJDI12) and the oral and gut microbiota in the general population of a rural area in Japan. After propensity-score matching, 396 participants (198 each in the low and high mJDI12 groups) were picked out. One year after the follow up survey, we reclassified the subjects and compared the low and high mJDI12 groups again. Participants with a high mJDI12 had a higher relative abundance of butyric acid-producing bacteria in their gut microbiota. Moreover, the significantly higher dietary fiber intake in the high mJDI12 group suggested that the high intake of dietary fiber contributed to an increase in butyric acid-producing bacteria in the gut. In contrast, in individuals with a high mJDI12, only Allpprevotella was decreased in the oral microbiota. Thus, the Japanese dietary pattern can have beneficial effects by improving the oral and gut microbiota.

The Link between Periodontal Disease and Asthma: How Do These Two Diseases Affect Each Other?

A growing body of evidence suggests that the effects of poor oral hygiene extend beyond the oral cavity and are associated with a variety of systemic diseases, including asthma. Asthma, which results in symptoms of cough, wheezing, and dyspnoea, and is characterized by airflow limitation with variability and (partial or complete) reversibility, is amongst the most prevalent respiratory diseases with approximately 262 million patients worldwide, and its prevalence and disease burden is on the increase. While asthma can occur at a young age, it can also develop later in life and affects a variety of age groups. Both of these diseases have a chronic course, and various researchers have suggested a link between the two. In this article, we aim to provide a literature review focusing on the association between the two diseases. The results demonstrate that medications (primarily, inhaler medicine), hypoxia induced by asthma, and the breathing behaviour of patients potentially trigger periodontal disease. In contrast, oral periodontopathogenic microorganisms and the inflammatory mediators produced by them may be involved in the onset and/or exacerbation of asthma. Common contributing factors, such as smoking, gastro-oesophageal reflux, and type-2 inflammation, should also be considered when evaluating the relationship between the two diseases.

Alterations of oral microbiota are associated with the development and severity of acute pancreatitis

Acute pancreatitis (AP) is a common abdomen clinical emergency. Most APs have mild clinical symptoms and a good prognosis. However, about 20% of patients develop severe acute pancreatitis (SAP), increasing morbidity and mortality. The microbiome's impact on AP pathophysiology has received increasing attention. Hence, to explore changes in oral microbial composition in acute pancreatitis, we collected clinical information and oral saliva samples from 136 adult participants: 47 healthy controls, 43 acute mild AP (MAP), 29 moderate AP (MSAP), and 17 severe AP (SAP). Using 16S rRNA gene sequencing, 663,175 high-quality sequences were identified. The relative abundance and diversity of oral microorganisms in AP patients increased, with decreased beneficial bacteria such as Streptococcus, Neisseria, and Gemella, and increased Prevotella, Veillonella, Granulicatella, Actinomyces, and Peptostreptococcus in the AP group. Further changes in microbial composition occurred with increasing disease severity, including a decreased abundance of beneficial bacteria such as Neisseria, Haemophilus, and Gemella in MSAP and SAP compared to MAP. Moreover, the Lefse analysis showed that Prevotella, Peptostreptococcus, Actinomyces, and Porphyromonas were better microbial markers for AP. Therefore, oral microbiome changes could distinguish AP from healthy individuals and serve as an early novel predictor of disease severity in AP patients.

A Review on Microbial Species for Forensic Body Fluid Identification in Healthy and Diseased Humans

Microbial communities present in body fluids can assist in distinguishing between types of body fluids. Metagenomic studies have reported bacterial genera which are core to specific body fluids and are greatly influenced by geographical location and ethnicity. Bacteria in body fluids could also be due to bacterial infection; hence, it would be worthwhile taking into consideration bacterial species associated with diseases. The present review reports bacterial species characteristic of diseased and healthy body fluids across geographical locations, and bacteria described in forensic studies, with the aim of collating a set of bacteria to serve as the core species-specific markers for forensic body fluid identification. The most widely reported saliva-specific bacterial species are Streptococcus salivarius, Prevotella melaninogenica, Neisseria flavescens, with Fusobacterium nucleatum associated with increased diseased state. Lactobacillus crispatus and Lactobacillus iners are frequently dominant in the vaginal microbiome of healthy women. Atopobium vaginae, Prevotella bivia, and Gardnerella vaginalis are more prevalent in women with bacterial vaginosis. Semen and urine-specific bacteria at species level have not been reported, and menstrual blood bacteria are indistinguishable from vaginal fluid. Targeting more than one bacterial species is recommended for accurate body fluid identification. Although metagenomic sequencing provides information of a broad microbial profile, the specific bacterial species could be used to design biosensors for rapid body fluid identification. Validation of microbial typing methods and its application in identifying body fluids in a mixed sample would allow regular use of microbial profiling in a forensic workflow.

Gut microbiota variation of a tropical oil-collecting bee species far exceeds that of the honeybee

Introduction

Interest for bee microbiota has recently been rising, alleviating the gap in knowledge in regard to drivers of solitary bee gut microbiota. However, no study has addressed the microbial acquisition routes of tropical solitary bees. For both social and solitary bees, the gut microbiota has several essential roles such as food processing and immune responses. While social bees such as honeybees maintain a constant gut microbiota by direct transmission from individuals of the same hive, solitary bees do not have direct contact between generations. They thus acquire their gut microbiota from the environment and/or the provision of their brood cell. To establish the role of life history in structuring the gut microbiota of solitary bees, we characterized the gut microbiota of Centris decolorata from a beach population in Mayagüez, Puerto Rico. Females provide the initial brood cell provision for the larvae, while males patrol the nest without any contact with it. We hypothesized that this behavior influences their gut microbiota, and that the origin of larval microbiota is from brood cell provisions.

Methods

We collected samples from adult females and males of C. decolorata (n = 10 each, n = 20), larvae (n = 4), and brood cell provisions (n = 10). For comparison purposes, we also sampled co-occurring female foragers of social Apis mellifera (n = 6). The samples were dissected, their DNA extracted, and gut microbiota sequenced using 16S rRNA genes. Pollen loads of A. mellifera and C. decolorata were analyzed and interactions between bee species and their plant resources were visualized using a pollination network.

Results

While we found the gut of A. mellifera contained the same phylotypes previously reported in the literature, we noted that the variability in the gut microbiota of solitary C. decolorata was significantly higher than that of social A. mellifera. Furthermore, the microbiota of adult C. decolorata mostly consisted of acetic acid bacteria whereas that of A. mellifera mostly had lactic acid bacteria. Among C. decolorata, we found significant differences in alpha and beta diversity between adults and their brood cell provisions (Shannon and Chao1 p < 0.05), due to the higher abundance of families such as Rhizobiaceae and Chitinophagaceae in the brood cells, and of Acetobacteraceae in adults. In addition, the pollination network analysis indicated that A. mellifera had a stronger interaction with Byrsonima sp. and a weaker interaction with Combretaceae while interactions between C. decolorata and its plant resources were constant with the null model.

Conclusion

Our data are consistent with the hypothesis that behavioral differences in brood provisioning between solitary and social bees is a factor leading to relatively high variation in the microbiota of the solitary bee.

B cells as modulators of HPV+ oropharyngeal cancer in a preclinical model

Among the different immune cells present within tumors, B cells also infiltrate human papillomavirus-positive (HPV+) oropharyngeal tumors. However, the role of B cells during programmed death-1 (PD-1) blockade in HPV+ oropharyngeal cancer needs to be better defined. By using the preclinical mouse model for HPV+ oropharyngeal cancer (named mEER), we characterized B cells within tumors and determined their functional role in vivo during PD-1 blockade. We determined that treatment naïve tongue-implanted tumors, which we have previously demonstrated to be sensitive to PD-1 blockade, contained high infiltration of CD8+ T cells and low infiltration of B cells whereas flank-implanted tumors, which are resistant to PD-1 blockade, contain a higher frequency of B cells compared to T cells. Moreover, B cell-deficient mice (µMt) and B cell-depleted mice showed a slower tumor growth rate compared to wild-type (WT) mice, and B cell deficiency increased CD8+ T cell infiltration in tumors. When we compared tongue tumor-bearing mice treated with anti-PD-1, we observed that tumors that responded to the therapy contained more T cells and B cells than the ones that did not respond. However, µMt mice treated with PD-1 blockade showed similar tumor growth rates to WT mice. Our data suggest that in untreated mice, B cells have a more pro-tumorigenic phenotype potentially affecting T cell infiltration in the tumors. In contrast, B cells are dispensable for PD-1 blockade efficacy. Mechanistic studies are needed to identify novel targets to promote the anti-tumorigenic function and/or suppress the immunosuppressive function of B cells in HPV+ oropharyngeal cancer.