Oral-gut connection: one step closer to an integrated view of the gastrointestinal tract?

Cinnamaldehyde Protects against P. gingivalis Induced Intestinal Epithelial Barrier Dysfunction in IEC-6 Cells via the PI3K/Akt-Mediated NO/Nrf2 Signaling Pathway

Porphyromonas gingivalis (Pg), a Gram-negative oral pathogen, promotes and accelerates periodontitis-associated gut disorders. Intestinal epithelial barrier dysfunction is crucial in the pathogenesis of intestinal and systemic diseases. In this study, we sought to elucidate the protective role of cinnamaldehyde (CNM, an activator of Nrf2) against P. gingivalis (W83) and Pg-derived lipopolysaccharide (Pg-LPS) induced intestinal epithelial barrier dysfunction via antioxidative mechanisms in IEC-6 cells. IEC-6 (ATCC, CRL-1592) cells were pretreated with or without CNM (100 µM), in the presence or absence of P. gingivalis (strain W83, 109 MOI) or Pg-LPS (1, 10, and 100 µg/mL), respectively, between 0-72 h time points by adopting a co-culture method. Intestinal barrier function, cytokine secretion, and intestinal oxidative stress protein markers were analyzed. P. gingivalis or Pg-LPS significantly (p < 0.05) increased reactive oxygen species (ROS) and malondialdehyde (MDA) levels expressing oxidative stress damage. Pg-LPS, as well as Pg alone, induces inflammatory cytokines via TLR-4 signaling. Furthermore, infection reduced Nrf2 and NAD(P)H quinone dehydrogenase 1 (NQO1). Interestingly, inducible nitric oxide synthase (iNOS) protein expression significantly (p < 0.05) increased with Pg-LPS or Pg infection, with elevated levels of nitric oxide (NO). CNM treatment suppressed both Pg- and Pg-LPS-induced intestinal oxidative stress damage by reducing ROS, MDA, and NO production. Furthermore, CNM treatment significantly upregulated the expression of tight junction proteins via increasing the phosphorylation levels of PI3K/Akt/Nrf2 suppressing inflammatory cytokines. CNM protected against Pg infection-induced intestinal epithelial barrier dysfunction by activating the PI3K/Akt-mediated Nrf2 signaling pathway in IEC-6 cells.

Ectopic colonization by oral bacteria as an emerging theme in health and disease

The number of research papers published on the involvement of the oral microbiota in systemic diseases has grown exponentially over the last 4 years clearly demonstrating the growing interest in this field. Indeed, accumulating evidence highlights the central role of ectopic colonization by oral bacteria in numerous noncommunicable diseases including inflammatory bowel diseases (IBDs), undernutrition, preterm birth, neurological diseases, liver diseases, lung diseases, heart diseases, or colonic cancer. There is thus much interest in understanding the molecular mechanisms that lead to the colonization and maintenance of ectopic oral bacteria. The aim of this review is to summarize and conceptualize the current knowledge about ectopic colonization by oral bacteria, highlight wherever possible the underlying molecular mechanisms and describe its implication in health and disease. The focus lies on the newly discovered molecular mechanisms, showcasing shared pathophysiological mechanisms across different body sites and syndromes and highlighting open questions in the field regarding the pathway from oral microbiota dysbiosis to noncommunicable diseases.

Oral microbiota-host interaction: the chief culprit of alveolar bone resorption

There exists a bidirectional relationship between oral health and general well-being, with an imbalance in oral symbiotic flora posing a threat to overall human health. Disruptions in the commensal flora can lead to oral diseases, while systemic illnesses can also impact the oral cavity, resulting in the development of oral diseases and disorders. Porphyromonas gingivalis and Fusobacterium nucleatum, known as pathogenic bacteria associated with periodontitis, play a crucial role in linking periodontitis to accompanying systemic diseases. In periodontal tissues, these bacteria, along with their virulence factors, can excessively activate the host immune system through local diffusion, lymphatic circulation, and blood transmission. This immune response disruption contributes to an imbalance in osteoimmune mechanisms, alveolar bone resorption, and potential systemic inflammation. To restore local homeostasis, a deeper understanding of microbiota-host interactions and the immune network phenotype in local tissues is imperative. Defining the immune network phenotype in periodontal tissues offers a promising avenue for investigating the complex characteristics of oral plaque biofilms and exploring the potential relationship between periodontitis and associated systemic diseases. This review aims to provide an overview of the mechanisms underlying Porphyromonas gingivalis- and Fusobacterium nucleatum-induced alveolar bone resorption, as well as the immunophenotypes observed in host periodontal tissues during pathological conditions.

Decentralized ORP Measurements for Gut Redox Status Monitoring: Toward Personalized Gut Microbiota Balance

Gut microbiome targeting has emerged as a new generation of personalized medicine and a potential wellness and disease driver. Specifically, the gut redox balance plays a key role in shaping the gut microbiota and its link with the host, immune system, and disease evolution. In this sense, precise and personalized nutrition has proven synergy and capability to modulate the gut microbiome environment through the formulation of dietary interventions, such as vitamin support. Accordingly, there are urgent demands for simple and effective analytical platforms for understanding the relationship between the tailored vitamin administration and the gut microbiota balance by rapid noninvasive on-the-spot oxidation/reduction potential monitoring for frequent and close surveillance of the gut redox status and targeting by personalized nutrition interventions. Herein, we present a disposable potentiometric sensor chip and a homemade multiwell potentiometric array to address the interplay of vitamin levels with the oxidation/reduction potential in human feces and saliva. The potentiometric ORP sensing platforms have been successfully validated and scaled up for the setup of a multiapplication prototype for cross-talk-free simple screening of many specimens. The interpersonal variability of the gut microbiota environment illustrates the potential of feces and saliva samples for noninvasive, frequent, and decentralized monitoring of the gut redox status to support timely human microbiota surveillance and guide precise dietary intervention toward restoring and promoting personalized gut redox balance.

The gut microbiome meets nanomaterials: exposure and interplay with graphene nanoparticles

Graphene-based nanoparticles are widely applied in many technology and science sectors, raising concerns about potential health risks. Emerging evidence suggests that graphene-based nanomaterials may interact with microorganisms, both pathogens and commensal bacteria, that dwell in the gut. This review aims to demonstrate the current state of knowledge on the interplay between graphene nanomaterials and the gut microbiome. In this study, we briefly overview nanomaterials, their usage and the characteristics of graphene-based nanoparticles. We present and discuss experimental data from in vitro studies, screening tests on small animals and rodent experiments related to exposure and the effects of graphene nanoparticles on gut microbiota. With this in mind, we highlight the reported crosstalk between graphene nanostructures, the gut microbial community and the host immune system in order to shed light on the perspective to bear on the biological interactions. The studies show that graphene-based material exposure is dosage and time-dependent, and different derivatives present various effects on host bacteria cells. Moreover, the route of graphene exposure might influence a shift in the gut microbiota composition, including the alteration of functions and diversity and abundance of specific phyla or genera. However, the mechanism of graphene-based nanomaterials' influence on gut microbiota is poorly understood. Accordingly, this review emphasises the importance of studies needed to establish the most desirable synthesis methods, types of derivatives, properties, and safety aspects mainly related to the routes of exposure and dosages of graphene-based nanomaterials.

Salivary Microbiota Associated with Peripheral Microvascular Endothelial Dysfunction

AIMS

Oral health is associated with atherosclerotic cardiovascular disease (ACVD). We previously identified the salivary microbiota characteristics of patients with ACVD. However, whether salivary microbiota is characteristic under impaired vascular endothelial function before ACVD onset remains unclear. Therefore, we aimed to evaluate the characteristics of salivary microbiota associated with peripheral microvascular endothelial dysfunction.

METHODS

We collected saliva samples from 172 community-dwelling elderly individuals without a history of ACVD and performed 16S rRNA metagenomic analysis. We assessed the peripheral microvascular endothelial function using reactive hyperemia index (RHI) and compared the salivary microbiota in the groups with normal (RHI ≥ 2.10), borderline, and abnormal (RHI ＜1.67) peripheral endothelial function. Furthermore, we applied machine learning techniques to evaluate whether salivary microbiota could discriminate between individuals with normal and abnormal endothelial function.

RESULTS

The number of operational taxonomic units (OTUs) was higher in the abnormal group than in the normal group (p=0.037), and differences were found in the overall salivary microbiota structure (unweighted UniFrac distances, p=0.038). The linear discriminant analysis (LDA) effect size (LEfSe) algorithm revealed several significantly differentially abundant bacterial genera between the two groups. An Extra Trees classifier model was built to discriminate between groups with normal and abnormal vascular endothelial function based on the microbial composition at the genus level (AUC=0.810).

CONCLUSIONS

The salivary microbiota in individuals with endothelial dysfunction was distinct from that in individuals with normal endothelial function, indicating that the salivary microbiota may be related to endothelial function.

The fascinating microbes and their impact on neonatal dogs and cats - A review

Recent literature data indicate that canine and feline neonates are not born in a sterile environment as it was stated previously. The acquisition, colonisation and maintenance of the early life microbiota of healthy fetuses is a rapidly developing research area. In humans, the natural healthy infant microbiome plays an essential role in health and its assembly is determined by the maternal-offspring exchanges of microbes. Even though this topic is becoming more and more important in dogs and cats, the exact role of the neonatal microbiome is not yet fully known in animals. This review summarises the current knowledge of the normal physiological neonatal microbiome in healthy puppies and kittens.

Inflammatory response of gut, spleen, and liver in mice induced by orally administered Porphyromonas gingivalis

Background

Periodontitis is a chronic multifactorial inflammatory disease. Porphyromonas gingivalis is a primary periopathogen in the initiation and development of periodontal disease. Evidence has shown that P. gingivalis is associated with systemic diseases, including IBD and fatty liver disease. Inflammatory response is a key feature of diseases related to this species.

Methods

C57BL/6 mice were administered either PBS, or P. gingivalis. After 9 weeks, the inflammatory response in gut, spleen, and liver was analyzed.

Results

The findings revealed significant disturbance of the intestinal microbiota and increased inflammatory factors in the gut of P. gingivalis-administered mice. Administrated P. gingivalis remarkably promoted the secretion of IRF-1 and activated the inflammatory pathway IFN-γ/STAT1 in the spleen. Histologically, mice treated with P. gingivalis exhibited hepatocyte damage and lipid deposition. The inflammatory factors IL-17a, IL-6, and ROR-γt were also upregulated in the liver of mice fed with P. gingivalis. Lee’s index, spleen index, and liver index were also increased.

Conclusion

These results suggest that administrated P. gingivalis evokes inflammation in gut, spleen, and liver, which might promote the progression of various systemic diseases.

Diversity and Biogeography of Human Oral Saliva Microbial Communities Revealed by the Earth Microbiome Project

The oral cavity is an important window for microbial communication between the environment and the human body. The oral microbiome plays an important role in human health. However, compared to the gut microbiome, the oral microbiome has been poorly explored. Here, we analyzed 404 datasets from human oral saliva samples published by the Earth Microbiome Project (EMP) and compared them with 815 samples from the human gut, nose/pharynx, and skin. The diversity of the human saliva microbiome varied significantly among individuals, and the community compositions were complex and diverse. The saliva microbiome showed the lowest species diversity among the four environment types. Human oral habitats shared a small core bacterial community containing only 14 operational taxonomic units (OTUs) under 5 phyla, which occupied over 75% of the sequence abundance. For the four habitats, the core taxa of the saliva microbiome had the greatest impact on saliva habitats than other habitats and were mostly unique. In addition, the saliva microbiome showed significant differences in the populations of different regions, which may be determined by the living environment and lifestyle/dietary habits. Finally, the correlation analysis showed high similarity between the saliva microbiome and the microbiomes of Aerosol (non-saline) and Surface (non-saline), i.e., two environment types closely related to human, suggesting that contact and shared environment being the driving factors of microbial transmission. Together, these findings expand our understanding of human oral diversity and biogeography.

Characterization of Altered Oropharyngeal Microbiota in Hospitalized Patients With Mild SARS-CoV-2 Infection

Coronavirus disease 2019 (COVID-19) remains a serious emerging global health problem, and little is known about the role of oropharynx commensal microbes in infection susceptibility and severity. Here, we present the oropharyngeal microbiota characteristics identified by full-length 16S rRNA gene sequencing through the NANOPORE platform of oropharynx swab specimens from 10 mild COVID-19 patients and 10 healthy controls. Our results revealed a distinct oropharyngeal microbiota composition in mild COVID-19 patients, characterized by enrichment of opportunistic pathogens such as Peptostreptococcus anaerobius and Pseudomonas stutzeri and depletion of Sphingomonas yabuuchiae, Agrobacterium sullae, and Pseudomonas veronii. Based on the relative abundance of the oropharyngeal microbiota at the species level, we built a microbial classifier to distinguish COVID-19 patients from healthy controls, in which P. veronii, Pseudomonas fragi, and S. yabuuchiae were identified as the most prominent signatures for their depletion in the COVID-19 group. Several members of the genus Campylobacter, especially Campylobacter fetus and Campylobacter rectus, which were highly enriched in COVID-19 patients with higher severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load and showed a significant correlation with disease status and several routine clinical blood indicators, indicate that several bacteria may transform into opportunistic pathogen in COVID-19 patients when facing the challenges of viral infection. We also found the diver taxa Streptococcus anginosus and Streptococcus alactolyticus in the network of disease patients, suggesting that these oropharynx microbiota alterations may impact COVID-19 severity by influencing the microbial association patterns. In conclusion, the low sample size of SARS-CoV-2 infection patients (n = 10) here makes these results tentative; however, we have provided the overall characterization that oropharyngeal microbiota alterations and microbial correlation patterns were associated with COVID-19 severity in Anhui Province.

Periodontitis, chronic liver diseases, and the emerging oral-gut-liver axis

The liver carries out a wide range of functions ranging from the control of metabolites, nutrient storage, and detoxification to immunosurveillance. While inflammation is essential for the tissue remodeling and maintenance of homeostasis and normal liver physiology, constant exposure to dietary and microbial products creates a niche for potentially prolonged immune activation and unresolved inflammation in susceptible host. Failure to restrain inflammation can lead to development of chronic liver diseases characterized by fibrosis, cirrhosis and eventually liver failure. The liver maintains close interactions with numerous organs which can influence its metabolism and physiology. It is also known that oral cavity microenvironment can influence the physiological conditions of other organs and emerging evidence implicates that this could be true for the liver as well. Presence of chronic inflammation and dysbiotic microbiota is a common feature leading to clinical pathology both in periodontitis and chronic liver diseases (CLDs). In fact, known CLDs appear to have some relationship with periodontitis, which impacts the onset or progression of these conditions in a bidirectional crosstalk. In this review, we explore the emerging association between oral‐gut‐liver axis focusing on periodontitis and common CLDs including nonalcoholic fatty liver disease, chronic viral hepatitis, liver cirrhosis, and hepatocellular cancer. We highlight the immune pathways and oral microbiome interactions which can link oral cavity and liver health and offer perspectives for future research.

Current knowledge of anthocyanin metabolism in the digestive tract: absorption, distribution, degradation, and interconversion

Potential roles for anthocyanins in preventing various chronic diseases have been reported. These compounds are highly sensitive to external conditions and are susceptible to degradation, which increases the complexity of their metabolism in vivo. This review discusses anthocyanin metabolism in the digestive tract, phase I and II metabolism, and enterohepatic circulation (EHC), as well as their distribution of anthocyanins in blood, urine, and several organs. In the oral cavity, anthocyanins are partly hydrolyzed by microbiota into aglycones which are then conjugated by glucuronidase. In stomach, anthocyanins are absorbed without deglycosylation via specific transporters, such as sodium-dependent glucose co-transporter 1 and facilitative glucose transporters 1, while in small intestine, they are mainly absorbed as aglycones. High polymeric anthocyanins are easily degraded into low-polymeric forms or smaller phenolic acids by colonic microbiota, which improves their absorption. Anthocyanins and their derivatives are modified by phase I and II metabolic enzymes in cells and are released into the blood via the gastrovascular cavity into EHC. Notably, interconversion can be occurred under the action of enzymes such as catechol-O-methyltransferase. Taking together, differences in anthocyanin absorption, distribution, metabolism, and excretion largely depend on their glycoside and aglycone structures.

A genetic association study reveals the relationship between the oral microbiome and anxiety and depression symptoms

BACKGROUND

Growing evidence supports that alterations in the gut microbiota play an essential role in the etiology of anxiety, depression, and other psychiatric disorders. However, the potential effect of oral microbiota on mental health has received little attention.

METHODS

Using the latest genome-wide association study (GWAS) summary data of the oral microbiome, polygenic risk scores (PRSs) of 285 salivary microbiomes and 309 tongue dorsum microbiomes were conducted. Logistic and linear regression models were applied to evaluate the relationship between salivary-tongue dorsum microbiome interactions with anxiety and depression. Two-sample Mendelian randomization (MR) was utilized to compute the causal effects between the oral microbiome, anxiety, and depression.

RESULTS

We observed significant salivary-tongue dorsum microbiome interactions related to anxiety and depression traits. Significantly, one common interaction was observed to be associated with both anxiety score and depression score, Centipeda periodontii SGB 224 × Granulicatella uSGB 3289 (P _{depressionscore} = 1.41 × 10^-8, P _anxietyscore = 5.10 × 10^-8). Furthermore, we detected causal effects between the oral microbiome and anxiety and depression. Importantly, we identified one salivary microbiome associated with both anxiety and depression in both the UKB database and the Finngen public database, Eggerthia (P _{IVW - majordepression - UKB} = 2.99 × 10^-6, P _{IVW - Self - reportedanxiety/panicattacks - UKB} = 3.06 × 10^-59, P _{IVW - depression - Finngen} = 3.16 × 10 , - 16 P _{IVW - anxiety - Finngen} = 1.14 × 10^-115).

CONCLUSION

This study systematically explored the relationship between the oral microbiome and anxiety and depression, which could help improve our understanding of disease pathogenesis and propose new diagnostic targets and early intervention strategies.

Adaptive immune cells shape obesity-associated type 2 diabetes mellitus and less prominent comorbidities

Obesity and type 2 diabetes mellitus (T2DM) are increasing in prevalence owing to decreases in physical activity levels and a shift to diets that include addictive and/or high-calorie foods. These changes are associated with the adoption of modern lifestyles and the presence of an obesogenic environment, which have resulted in alterations to metabolism, adaptive immunity and endocrine regulation. The size and quality of adipose tissue depots in obesity, including the adipose tissue immune compartment, are critical determinants of overall health. In obesity, chronic low-grade inflammation can occur in adipose tissue that can progress to systemic inflammation; this inflammation contributes to the development of insulin resistance, T2DM and other comorbidities. An improved understanding of adaptive immune cell dysregulation that occurs during obesity and its associated metabolic comorbidities, with an appreciation of sex differences, will be critical for repurposing or developing immunomodulatory therapies to treat obesity and/or T2DM-associated inflammation. This Review critically discusses how activation and metabolic reprogramming of lymphocytes, that is, T cells and B cells, triggers the onset, development and progression of obesity and T2DM. We also consider the role of immunity in under-appreciated comorbidities of obesity and/or T2DM, such as oral cavity inflammation, neuroinflammation in Alzheimer disease and gut microbiome dysbiosis. Finally, we discuss previous clinical trials of anti-inflammatory medications in T2DM and consider the path forward.

Post-translational Modifications in Oral Bacteria and Their Functional Impact

Oral bacteria colonize the oral cavity, surrounding complex and variable environments. Post-translational modifications (PTMs) are an efficient biochemical mechanism across all domains of life. Oral bacteria could depend on PTMs to quickly regulate their metabolic processes in the face of external stimuli. In recent years, thanks to advances in enrichment strategies, the number and variety of PTMs that have been identified and characterized in oral bacteria have increased. PTMs, covalently modified by diverse enzymes, occur in amino acid residues of the target substrate, altering the functions of proteins involved in different biological processes. For example, Ptk1 reciprocally phosphorylates Php1 on tyrosine residues 159 and 161, required for Porphyromonas gingivalis EPS production and community development with the antecedent oral biofilm constituent Streptococcus gordonii, and in turn Php1 dephosphorylates Ptk1 and rapidly causes the conversion of Ptk1 to a state of low tyrosine phosphorylation. Protein acetylation is also widespread in oral bacteria. In the acetylome of Streptococcus mutans, 973 acetylation sites were identified in 445 proteins, accounting for 22.7% of overall proteins involving virulence factors and pathogenic processes. Other PTMs in oral bacteria include serine or threonine glycosylation in Cnm involving intracerebral hemorrhage, arginine citrullination in peptidylarginine deiminases (PADs), leading to inflammation, lysine succinylation in P. gingivalis virulence factors (gingipains, fimbriae, RagB, and PorR), and cysteine glutathionylation in thioredoxin-like protein (Tlp) in response to oxidative stress in S. mutans. Here we review oral bacterial PTMs, focusing on acetylation, phosphorylation, glycosylation, citrullination, succinylation, and glutathionylation, and corresponding modifying enzymes. We describe different PTMs in association with some examples, discussing their potential role and function in oral bacteria physiological processes and regulatory networks. Identification and characterization of PTMs not only contribute to understanding their role in oral bacterial virulence, adaption, and resistance but will open new avenues to treat oral infectious diseases.

Multifaceted Impacts of Periodontal Pathogens in Disorders of the Intestinal Barrier

Periodontal disease, a common inflammatory disease, is considered a hazardous factor that contributes to the development of diseases of the digestive system as well as other systems. The bridge between periodontitis and systemic diseases is believed to be periodontal pathogens. The intestine, as part of the lower gastrointestinal tract, has a close connection with the oral cavity. Within the intestine, the intestinal barrier acts as a multifunctional system including microbial, mucous, physical and immune barrier. The intestinal barrier forms the body's first line of defense against external pathogens; its breakdown can lead to pathological changes in the gut and other organs or systems. Reports in the literature have described how oral periodontal pathogens and pathobiont-reactive immune cells can transmigrate to the intestinal mucosa, causing the destruction of intestinal barrier homeostasis. Such findings might lead to novel ideas for investigating the relationship between periodontal disease and other systemic diseases. This review summarizes studies on the effects of periodontal pathogens on the intestinal barrier, which might contribute to understanding the link between periodontitis and gastrointestinal diseases.

Variations in the oral microbiome are associated with depression in young adults

A growing body of evidence supports an important role for alterations in the brain-gut-microbiome axis in the aetiology of depression and other psychiatric disorders. The potential role of the oral microbiome in mental health has received little attention, even though it is one of the most diverse microbiomes in the body and oral dysbiosis has been linked to systemic diseases with an underlying inflammatory aetiology. This study examines the structure and composition of the salivary microbiome for the first time in young adults who met the DSM-IV criteria for depression (n = 40) and matched controls (n = 43) using 16S rRNA gene-based next generation sequencing. Subtle but significant differences in alpha and beta diversity of the salivary microbiome were observed, with clear separation of depressed and healthy control cohorts into distinct clusters. A total of 21 bacterial taxa were found to be differentially abundant in the depressed cohort, including increased Neisseria spp. and Prevotella nigrescens, while 19 taxa had a decreased abundance. In this preliminary study we have shown that the composition of the oral microbiome is associated with depression in young adults. Further studies are now warranted, particuarly investigations into whether such shifts play any role in the underling aetiology of depression.

Patient factors related to early implant failures in the edentulous jaw: A large retrospective case-control study

BACKGROUND

Dental implants provide anchorage for dental prostheses to restore functions for individuals with edentulous jaws. During the healing phase, proper osseointegration is required to prevent early implant failure. More knowledge is needed regarding factors related to early failure of dental implants.

PURPOSE

The aim of the present study was to identify possible risk factors for early implant failure, with respect to anamnestic and clinical parameters.

MATERIALS AND METHODS

All patients with edentulous jaws with early implant failure (n = 408) from one referral clinic were compared with a matched control group (n = 408) with no implant failure. Early implant failure was identified during the first year of prosthetic function. Matching was performed on age, gender, year of surgery, type of jaw, and type of implant surface. In addition, data on anamnestic and clinical parameters were collected. The data were analyzed with a multivariable logistic regression model using early implant failure as the binary outcome.

RESULTS

Five anamnestic factors were statistically significant with respect to higher probability for early implant failure: systemic disease, allergies in general, food allergies, smoking, and intake of analgesic medication. Four clinical conditions (i.e., implants in the opposing jaw, low primary stability, reduced bone volume, and healing complications) were also related to higher probability for early implant failure.

CONCLUSIONS

This study identified nine factors associated with early implant failure, several related to patient's general health. Further investigations are needed to fully understand the causality between the obtained variables and early implant failure.

Effects of altitude on human oral microbes

Human oral microbes play a vital role maintaining host metabolic homeostasis. The Qinghai-Tibet Plateau is mainly characterized by a high altitude, dry, cold, and hypoxic environment. The oral microbiota is subject to selective pressure from the plateau environment, which affects oral health. Only a few studies have focused on the characteristics of oral microbiota in high-altitude humans. We collected saliva samples from 167 Tibetans at four altitudes (2800 to 4500 m) in Tibet to explore the relationship between the high altitude environment and oral microbiota. We conducted a two (high- and ultra-high-altitude) group analysis based on altitude, and adopted the 16S rRNA strategy for high-throughput sequencing. The results show that the alpha diversity of the oral microbiota decreased with altitude, whereas beta diversity increased with altitude. A LEfSe analysis revealed that the oral microbial biomarker of the high-altitude group (< 3650 m) was Streptococcus, and the biomarker of the ultra-high-altitude group (> 4000 m) was Prevotella. The relative abundance of Prevotella increased with altitude, whereas the relative abundance of Streptococcus decreased with altitude. A network analysis showed that the microbial network structure was more compact and complex, and the interaction between the bacterial genera was more intense in the high altitude group. Gene function prediction results showed that the amino acid and vitamin metabolic pathways were upregulated in the ultra-high-altitude group. These result show that altitude is an important factor affecting the diversity and community structure of the human oral microbiota.

Characterization of Salivary Microbiota in Patients with Atherosclerotic Cardiovascular Disease: A Case-Control Study

Aims: Oral bacteria have been reported to be associated with the pathogenesis of atherosclerosis; however, the relationship between the oral microbiota and atherosclerosis remains unclear. The present study aimed to investigate whether or not salivary microbiota of patients with atherosclerotic cardiovascular disease (ACVD) differs from that of subjects without ACVD, and to characterize the salivary microbiota of patients with ACVD.

Methods: This study included 43 patients with ACVD and 86 age- and sex-matched non-ACVD individuals. 16S rRNA metagenomic analysis were performed using DNA isolated from the saliva samples of the participants. To select unique operational taxonomic unit (OTU) sets of ACVD, we conducted the random forest algorithm in machine learning, followed by confirmation via 10-fold cross-validation

Results: There was no difference in richness or evenness between the ACVD and non-ACVD groups (alpha diversity; observed OTU index, p =0.503; Shannon’s index, p =0.478). However, significant differences were found in the overall salivary microbiota structure (beta diversity; unweighted UniFrac distances, p =0.001; weighted UniFrac distances, p =0.001). The Actinobacteria phylum was highly abundant in patients with ACVD, while the Bacteroidetes phylum was less abundant. The random forest classifier identified 43 OTUs as an optimal marker set of ACVD. In a 10-fold cross validation using the validation data, an area under the curve (AUC) of 0.933 (95% CI, 0.855–1.000) was obtained.

Conclusions: The salivary microbiota in patients with ACVD was distinct from that of non-ACVD individuals, indicating that the salivary microbiota may be related to ACVD.

Ingestion of Porphyromonas gingivalis exacerbates colitis via intestinal epithelial barrier disruption in mice

OBJECTIVE

This study aimed to evaluate the effects of ingested periodontal pathogens on experimental colitis in mice and to elucidate its underlying mechanisms.

BACKGROUND

Inflammatory bowel disease (IBD) is defined as a chronic intestinal inflammation that results in damage to the gastrointestinal tract. Epidemiological studies have shown an association between IBD and periodontitis. Although a large number of ingested oral bacteria reach gastrointestinal tract constantly, the effect of ingested periodontal pathogens on intestinal inflammation is still unknown.

METHODS

Experimental colitis was induced by inclusion of dextran sodium sulfate solution in drinking water of the mice. Major periodontal pathogens (Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum) were administered orally every day during the experiment. The severity of colitis between the groups was compared. In vitro studies of the intestinal epithelial cell line were conducted to explore the molecular mechanisms by which periodontal pathogens affect the development of colitis.

RESULTS

The oral administration of P. gingivalis significantly increased the severity of colitis when compared to other pathogens in the DSS-induced colitis model. The ingested P. gingivalis disrupted the colonic epithelial barrier by decreasing the expression of tight junction proteins in vivo. In vitro permeability assays using the intestinal epithelial cell line suggested the P. gingivalis-specific epithelial barrier disruption. The possible involvement of gingipains in the exacerbation of colitis was implied by using P. gingivalis lacking gingipains.

CONCLUSION

Porphyromonas gingivalis exacerbates gastrointestinal inflammation by directly interacting with the intestinal epithelial barrier in a susceptible host.

The Immunopathogenesis of Alzheimer's Disease Is Related to the Composition of Gut Microbiota

The microbiota-gut-brain axis plays an important role in the development of neurodegenerative diseases. Commensal and pathogenic enteric bacteria can influence brain and immune system function by the production of lipopolysaccharides and amyloid. Dysbiosis of the intestinal microbiome induces local and consecutively systemic immune-mediated inflammation. Proinflammatory cytokines then trigger neuroinflammation and finally neurodegeneration. Immune-mediated oxidative stress can lead to a deficiency of vitamins and essential micronutrients. Furthermore, the wrong composition of gut microbiota might impair the intake and metabolization of nutrients. In patients with Alzheimer's disease (AD) significant alterations of the gut microbiota have been demonstrated. Standard Western diet, infections, decreased physical activity and chronic stress impact the composition and diversity of gut microbiota. A higher abundancy of "pro-inflammatory" gut microbiota goes along with enhanced systemic inflammation and neuroinflammatory processes. Thus, AD beginning in the gut is closely related to the imbalance of gut microbiota. Modulation of gut microbiota by Mediterranean diet, probiotics and curcumin can slow down cognitive decline and alter the gut microbiome significantly. A multi-domain intervention approach addressing underlying causes of AD (inflammation, infections, metabolic alterations like insulin resistance and nutrient deficiency, stress) appears very promising to reduce or even reverse cognitive decline by exerting positive effects on the gut microbiota.

Impact of the repurposed drug thonzonium bromide on host oral-gut microbiomes

Drug repurposing is a feasible strategy for the development of novel therapeutic applications. However, its potential use for oral treatments and impact on host microbiota remain underexplored. Here, we assessed the influences of topical oral applications of a repurposed FDA-approved drug, thonzonium bromide, on gastrointestinal microbiomes and host tissues in a rat model of dental caries designed to reduce cross-contamination associated with coprophagy. Using this model, we recapitulated the body site microbiota that mirrored the human microbiome profile. Oral microbiota was perturbed by the treatments with specific disruption of Rothia and Veillonella without affecting the global composition of the fecal microbiome. However, disturbances in the oral-gut microbial interactions were identified using nestedness and machine learning, showing increased sharing of oral taxon Sutterella in the gut microbiota. Host-tissue analyses revealed caries reduction on teeth by thonzonium bromide without cytotoxic effects, indicating bioactivity and biocompatibility when used orally. Altogether, we demonstrate how an oral treatment using a repurposed drug causes localized microbial disturbances and therapeutic effects while promoting turnover of specific oral species in the lower gut in vivo.

The Effects of Nutrition on the Gastrointestinal Microbiome of Cats and Dogs: Impact on Health and Disease

The gastrointestinal (GI) microbiome of cats and dogs is increasingly recognized as a metabolically active organ inextricably linked to pet health. Food serves as a substrate for the GI microbiome of cats and dogs and plays a significant role in defining the composition and metabolism of the GI microbiome. The microbiome, in turn, facilitates the host's nutrient digestion and the production of postbiotics, which are bacterially derived compounds that can influence pet health. Consequently, pet owners have a role in shaping the microbiome of cats and dogs through the food they choose to provide. Yet, a clear understanding of the impact these food choices have on the microbiome, and thus on the overall health of the pet, is lacking. Pet foods are formulated to contain the typical nutritional building blocks of carbohydrates, proteins, and fats, but increasingly include microbiome-targeted ingredients, such as prebiotics and probiotics. Each of these categories, as well as their relative proportions in food, can affect the composition and/or function of the microbiome. Accumulating evidence suggests that dietary components may impact not only GI disease, but also allergies, oral health, weight management, diabetes, and kidney disease through changes in the GI microbiome. Until recently, the focus of microbiome research was to characterize alterations in microbiome composition in disease states, while less research effort has been devoted to understanding how changes in nutrition can influence pet health by modifying the microbiome function. This review summarizes the impact of pet food nutritional components on the composition and function of the microbiome and examines evidence for the role of nutrition in impacting host health through the microbiome in a variety of disease states. Understanding how nutrition can modulate GI microbiome composition and function may reveal new avenues for enhancing the health and resilience of cats and dogs.

Modulation of Saliva Microbiota through Prebiotic Intervention in HIV-Infected Individuals

Human immunodeficiency virus (HIV) infection is characterized by an early depletion of the mucosal associated T helper (CD4+) cells that impair the host immunity and impact the oral and gut microbiomes. Although, the HIV-associated gut microbiota was studied in depth, few works addressed the dysbiosis of oral microbiota in HIV infection and, to our knowledge, no studies on intervention with prebiotics were performed. We studied the effect of a six-week-long prebiotic administration on the salivary microbiota in HIV patients and healthy subjects. Also, the co-occurrence of saliva microorganisms in the fecal bacteria community was explored. We assessed salivary and feces microbiota composition using deep 16S ribosomal RNA (rRNA) gene sequencing with Illumina methodology. At baseline, the different groups shared the same most abundant genera, but the HIV status had an impact on the saliva microbiota composition and diversity parameters. After the intervention with prebiotics, we found a drastic decrease in alpha diversity parameters, as well as a change of beta diversity, without a clear directionality toward a healthy microbiota. Interestingly, we found a differential response to the prebiotics, depending on the initial microbiota. On the basis of 100% identity clustering, we detected saliva sequences in the feces datasets, suggesting a drag of microorganisms from the upper to the lower gastrointestinal tract.

One Health, Fermented Foods, and Gut Microbiota

Changes in present-day society such as diets with more sugar, salt, and saturated fat, bad habits and unhealthy lifestyles contribute to the likelihood of the involvement of the microbiota in inflammatory diseases, which contribute to global epidemics of obesity, depression, and mental health concerns. The microbiota is presently one of the hottest areas of scientific and medical research, and exerts a marked influence on the host during homeostasis and disease. Fermented foods and beverages are generally defined as products made by microbial organisms and enzymatic conversions of major and minor food components. Further to the commonly-recognized effects of nutrition on the digestive health (e.g., dysbiosis) and well-being, there is now strong evidence for the impact of fermented foods and beverages (e.g., yoghurt, pickles, bread, kefir, beers, wines, mead), produced or preserved by the action of microorganisms, on general health, namely their significance on the gut microbiota balance and brain functionality. Fermented products require microorganisms, i.e., Saccharomyces yeasts and lactic acid bacteria, yielding alcohol and lactic acid. Ingestion of vibrant probiotics, especially those contained in fermented foods, is found to cause significant positive improvements in balancing intestinal permeability and barrier function. Our guts control and deal with every aspect of our health. How we digest our food and even the food sensitivities we have is linked with our mood, behavior, energy, weight, food cravings, hormone balance, immunity, and overall wellness. We highlight some impacts in this domain and debate calls for the convergence of interdisciplinary research fields from the United Nations’ initiative. Worldwide human and animal medicine are practiced separately; veterinary science and animal health are generally neither considered nor inserted within national or international Health discussions. The absence of a clear definition and subsequent vision for the future of One Health may act as a barrier to transdisciplinary collaboration. The point of this mini review is to highlight the role of fermented foods and beverages on gut microbiota and debate if the need for confluence of transdisciplinary fields of One Health is feasible and achievable, since they are managed by separate sectors with limited communication.

Altered oral microbiota in chronic hepatitis B patients with different tongue coatings

AIM

To elucidate tongue coating microbiota and metabolic differences in chronic hepatitis B (CHB) patients with yellow or white tongue coatings.

METHODS

Tongue coating samples were collected from 53 CHB patients (28 CHB yellow tongue coating patients and 25 CHB white tongue coating patients) and 22 healthy controls. Microbial DNA was extracted from the tongue samples, and the bacterial 16S ribosomal RNA gene V3 region was amplified from all samples and sequenced with the Ion Torrent PGM™ sequencing platform according to the standard protocols. The metabolites in the tongue coatings were evaluated using a liquid chromatography-mass spectrometry (LC-MS) platform. Statistical analyses were then performed.

RESULTS

The relative compositions of the tongue coating microbiotas and metabolites in the CHB patients were significantly different from those of the healthy controls, but the tongue coating microbiota abundances and diversity levels were not significantly different. Compared with the CHB white tongue coating patients, the CHB yellow tongue coating patients had higher hepatitis B viral DNA (HBV-DNA) titers (median 21210 vs 500, respectively, P = 0.03) and a significantly lower level of Bacteroidetes (20.14% vs 27.93%, respectively, P = 0.013) and higher level of Proteobacteria (25.99% vs 18.17%, respectively, P = 0.045) in the microbial compositions at the phylum level. The inferred metagenomic pathways enriched in the CHB yellow tongue coating patients were mainly those involved in amino acid metabolism, which was consistent with the metabolic disorder. The abundances of bacteria from Bacteroidales at the order level were higher in the CHB white tongue coating patients (19.2% vs 27.22%, respectively, P = 0.011), whereas Neisseriales were enriched in the yellow tongue coating patients (21.85% vs 13.83%, respectively, P = 0.029). At the family level, the abundance of Neisseriaceae in the yellow tongue patients was positively correlated with the HBV-DNA level but negatively correlated with the S-adenosyl-L-methionine level.

CONCLUSION

This research illustrates specific clinical features and bacterial structures in CHB patients with different tongue coatings, which facilitates understanding of the traditional tongue diagnosis.

The Gut Microbiome Alterations and Inflammation-Driven Pathogenesis of Alzheimer's Disease-a Critical Review

One of the most important scientific discoveries of recent years was the disclosure that the intestinal microflora takes part in bidirectional communication between the gut and the brain. Scientists suggest that human gut microflora may even act as the “second brain” and be responsible for neurodegenerative disorders like Alzheimer’s disease (AD). Although human-associated microbial communities are generally stable, they can be altered by common human actions and experiences. Enteric bacteria, commensal, and pathogenic microorganisms, may have a major impact on immune system, brain development, and behavior, as they are able to produce several neurotransmitters and neuromodulators like serotonin, kynurenine, catecholamine, etc., as well as amyloids. However, brain destructive mechanisms, that can lead to dementia and AD, start with the intestinal microbiome dysbiosis, development of local and systemic inflammation, and dysregulation of the gut-brain axis. Increased permeability of the gut epithelial barrier results in invasion of different bacteria, viruses, and their neuroactive products that support neuroinflammatory reactions in the brain. It seems that, inflammatory-infectious hypothesis of AD, with the great role of the gut microbiome, starts to gently push into the shadow the amyloid cascade hypothesis that has dominated for decades. It is strongly postulated that AD may begin in the gut, and is closely related to the imbalance of gut microbiota. This is promising area for therapeutic intervention. Modulation of gut microbiota through personalized diet or beneficial microbiota intervention, alter microbial partners and their products including amyloid protein, will probably become a new treatment for AD.

Oral microbiomes: more and more importance in oral cavity and whole body

Microbes appear in every corner of human life, and microbes affect every aspect of human life. The human oral cavity contains a number of different habitats. Synergy and interaction of variable oral microorganisms help human body against invasion of undesirable stimulation outside. However, imbalance of microbial flora contributes to oral diseases and systemic diseases. Oral microbiomes play an important role in the human microbial community and human health. The use of recently developed molecular methods has greatly expanded our knowledge of the composition and function of the oral microbiome in health and disease. Studies in oral microbiomes and their interactions with microbiomes in variable body sites and variable health condition are critical in our cognition of our body and how to make effect on human health improvement.