Subgingival Microbiome and Specialized Pro-Resolving Lipid Mediator Pathway Profiles Are Correlated in Periodontal Inflammation

Modulating the sEH/EETs Axis Restrains Specialized Proresolving Mediator Impairment and Regulates T Cell Imbalance in Experimental Periodontitis

Epoxyeicosatrienoic acids (EETs) and other epoxy fatty acids are short-acting lipids involved in resolution of inflammation. Their short half-life, due to its metabolism by soluble epoxide hydrolase (sEH), limits their effects. Specialized proresolving mediators (SPMs) are endogenous regulatory lipids insufficiently synthesized in uncontrolled and chronic inflammation. Using an experimental periodontitis model, we pharmacologically inhibited sEH, examining its impact on T cell activation and systemic SPM production. In humans, we analyzed sEH in the gingival tissue of periodontitis patients. Mice were treated with sEH inhibitor (sEHi) and/or EETs before ligature placement and treated for 14 d. Bone parameters were assessed by microcomputed tomography and methylene blue staining. Blood plasma metabololipidomics were carried out to quantify SPM levels. We also determined T cell activation by reverse transcription-quantitative PCR and flow cytometry in cervical lymph nodes. Human gingival samples were collected to analyze sEH using ELISA and electrophoresis. Data reveal that pharmacological sEHi abrogated bone resorption and preserved bone architecture. Metabololipidomics revealed that sEHi enhances lipoxin A4, lipoxin B4, resolvin E2, and resolvin D6. An increased percentage of regulatory T cells over Th17 was noted in sEHi-treated mice. Lastly, inflamed human gingival tissues presented higher levels and expression of sEH than did healthy gingivae, being positively correlated with periodontitis severity. Our findings indicate that sEHi preserves bone architecture and stimulates SPM production, associated with regulatory actions on T cells favoring resolution of inflammation. Because sEH is enhanced in human gingivae from patients with periodontitis and connected with disease severity, inhibition may prove to be an attractive target for managing osteolytic inflammatory diseases.

Manipulating the diseased oral microbiome: the power of probiotics and prebiotics

Dental caries and periodontal disease are amongst the most prevalent global disorders. Their aetiology is rooted in microbial activity within the oral cavity, through the generation of detrimental metabolites and the instigation of potentially adverse host immune responses. Due to the increasing threat of antimicrobial resistance, alternative approaches to readdress the balance are necessary. Advances in sequencing technologies have established relationships between disease and oral dysbiosis, and commercial enterprises seek to identify probiotic and prebiotic formulations to tackle preventable oral disorders through colonisation with, or promotion of, beneficial microbes. It is the metabolic characteristics and immunomodulatory capabilities of resident species which underlie health status. Research emphasis on the metabolic environment of the oral cavity has elucidated relationships between commensal and pathogenic organisms, for example, the sequential metabolism of fermentable carbohydrates deemed central to acid production in cariogenicity. Therefore, a focus on the preservation of an ecological homeostasis in the oral environment may be the most appropriate approach to health conservation. In this review we discuss an ecological approach to the maintenance of a healthy oral environment and debate the potential use of probiotic and prebiotic supplementation, specifically targeted at sustaining oral niches to preserve the delicately balanced microbiome.

Periodontal and cardiovascular therapies modify specialized pro-resolving lipid mediator (sPRLM) (LPXA4, PD1, RvE1, RvD1, and MaR1)-mediated pathway: the first pilot clinical study

OBJECTIVES

Cardiovascular disease (CVD) and periodontal disease have a common pathogenesis with inflammation and resolution steps. Although the relationships among periodontal disease, CVD, and specialized pro-resolving lipid mediator (sPRLM)s are well known, there is no study about the combined effects of cardiovascular and periodontal treatments on sPRLM levels. It was aimed to evaluate the effects of periodontal and cardiovascular therapies on sPRLMs (lipoxin A4, protectin (PD)1, resolvin (Rv) E1, RvD1, and maresin (MaR)1) in patients with CVD and periodontal disease.

METHODS

This observational study consisted of fifty-five patients with CVD and mild or moderate periodontitis. The clinical periodontal parameters (plaque index, gingival index, probing pocket depth, percentage of bleeding on probing, and clinical attachment level) and blood and unstimulated total saliva samples were obtained at baseline, at 3 months (following only cardiovascular therapy), and at 6 months (following cardiovascular and periodontal therapies). The blood count and serum levels of cardiometabolic biomarkers (white blood cell, neutrophil/lymphocyte, serum total cholesterol (TC), triglyceride, and low and high-density lipoprotein (HDL) levels) were evaluated. sPRLMs were evaluated by ELISA.

RESULTS

There were significant decreases in body mass index, clinical periodontal parameters, WBC, LDL, PD1, and RvD1 at 6 months compared to baseline. The decreases in TC/HDL, RvE1, and MaR1 levels were significant at 3 and 6 months compared to baseline (p < 0.05).

CONCLUSION(S)

The combination of cardiovascular and periodontal treatments leads to significant reductions in clinical periodontal and cardiometabolic parameters and sPRLMs.

CLINICAL RELEVANCE

Our report, which is the first in their field, suggested that cardiovascular and periodontal therapies provide an important contribution via decreasing the periodontal and atherosclerotic inflammation modulating sPRLMs. This finding will be a big step toward increasing the quality of life in these patients by drawing attention to importance of public health associated with oral hygiene, periodontal health, and systemic phase of periodontal treatment.

Roles of specialized pro-resolving mediators and omega-3 polyunsaturated fatty acids in periodontal inflammation and impact on oral microbiota

Periodontitis is a chronic inflammatory disease induced by dysbiotic dental biofilms. Management of periodontitis is primarily anti-bacterial via mechanical removal of bacterial biofilm. The successful resolution requires wound healing and tissue regeneration, which are not always achieved with these traditional methods. The discovery of specialized pro-resolving mediators (SPMs), a class of lipid mediators that induce the resolution of inflammation and promote local tissue homeostasis, creates another option for the treatment of periodontitis and other diseases of chronic inflammation. In this mini-review, we discuss the host-modulatory effects of SPMs on periodontal tissues and changes in the taxonomic composition of the gut and oral microbiome in the presence of SPMs and SPM precursor lipids. Further research into the relationship between host SPM production and microbiome-SPM modification has the potential to unveil new diagnostic markers of inflammation and wound healing. Expanding this field may drive the discovery of microbial-derived bioactive therapeutics to modulate immune responses.

Maresin: Macrophage Mediator for Resolving Inflammation and Bridging Tissue Regeneration-A System-Based Preclinical Systematic Review

Maresins are lipid mediators derived from omega-3 fatty acids with anti-inflammatory and pro-resolving properties, capable of promoting tissue regeneration and potentially serving as a therapeutic agent for chronic inflammatory diseases. The aim of this review was to systematically investigate preclinical and clinical studies on maresin to inform translational research. Two independent reviewers performed comprehensive searches with the term "Maresin (NOT) Review" on PubMed. A total of 137 studies were included and categorized into 11 human organ systems. Data pertinent to clinical translation were specifically extracted, including delivery methods, optimal dose response, and specific functional efficacy. Maresins generally exhibit efficacy in treating inflammatory diseases, attenuating inflammation, protecting organs, and promoting tissue regeneration, mostly in rodent preclinical models. The nervous system has the highest number of original studies (n = 25), followed by the cardiovascular system, digestive system, and respiratory system, each having the second highest number of studies (n = 18) in the field. Most studies considered systemic delivery with an optimal dose response for mouse animal models ranging from 4 to 25 μg/kg or 2 to 200 ng via intraperitoneal or intravenous injection respectively, whereas human in vitro studies ranged between 1 and 10 nM. Although there has been no human interventional clinical trial yet, the levels of MaR1 in human tissue fluid can potentially serve as biomarkers, including salivary samples for predicting the occurrence of cardiovascular diseases and periodontal diseases; plasma and synovial fluid levels of MaR1 can be associated with treatment response and defining pathotypes of rheumatoid arthritis. Maresins exhibit great potency in resolving disease inflammation and bridging tissue regeneration in preclinical models, and future translational development is warranted.

Illuminating the oral microbiome and its host interactions: animal models of disease

Periodontitis and caries are driven by complex interactions between the oral microbiome and host factors, i.e. inflammation and dietary sugars, respectively. Animal models have been instrumental in our mechanistic understanding of these oral diseases, although no single model can faithfully reproduce all aspects of a given human disease. This review discusses evidence that the utility of an animal model lies in its capacity to address a specific hypothesis and, therefore, different aspects of a disease can be investigated using distinct and complementary models. As in vitro systems cannot replicate the complexity of in vivo host-microbe interactions and human research is typically correlative, model organisms-their limitations notwithstanding-remain essential in proving causality, identifying therapeutic targets, and evaluating the safety and efficacy of novel treatments. To achieve broader and deeper insights into oral disease pathogenesis, animal model-derived findings can be synthesized with data from in vitro and clinical research. In the absence of better mechanistic alternatives, dismissal of animal models on fidelity issues would impede further progress to understand and treat oral disease.

Association between atherogenic index of plasma and periodontitis among U.S. adults

BACKGROUND

Serum lipids have been proven to influence periodontitis. The atherogenic index of plasma (AIP) is an important marker of lipid levels. The purpose of this study was to investigate the association between periodontitis and AIP in adults.

METHODS

The study included participants from the 2009-2014 National Health and Nutrition Examination Survey who received a complete periodontal exam and a complete record of AIP. AIP was calculated as log₁₀ (triglycerides/high-density lipoprotein cholesterol). Periodontitis can be classified into four categories based on attachment loss and probing depth (no periodontitis, moderate periodontitis, mild periodontitis, and severe periodontitis). Multivariable logistic regression after adjusting and hierarchical analysis were conducted to investigate the relationship between periodontitis and AIP in adults.

RESULTS

The final sample included 4,371 participants, representing approximately 60 million people in the United States. Periodontitis among the AIP groups (quartile, Q1-Q4) was statistically significant (P < 0.05). Univariate analysis showed that AIP was associated with the incidence of periodontitis (P < 0.05), but not with the severity of periodontitis (P > 0.05) in participants. Multifactorial logistic regression analysis showed no correlation between the incidence of periodontitis and AIP among all participants (the trend P-value = 0.341), but a significant association with AIP in the non-smoking participants (the trend P-value = 0.031).

CONCLUSION

There was a significant correlation between periodontitis and AIP in the non-smoking population.

Oral microbial dysbiosis in patients with periodontitis and chronic obstructive pulmonary disease

Background

Oral microbiota is closely related to the homeostasis of the oral cavity and lungs. To provide potential information for the prediction, screening, and treatment strategies of individuals, this study compared and investigated the bacterial signatures in periodontitis and chronic obstructive pulmonary disease (COPD).

Materials and methods

We collected subgingival plaque and gingival crevicular fluid samples from 112 individuals (31 healthy controls, 24 patients with periodontitis, 28 patients with COPD, and 29 patients with both periodontitis and COPD). The oral microbiota was analyzed using 16S rRNA gene sequencing and diversity and functional prediction analysis were performed.

Results

We observed higher bacterial richness in individuals with periodontitis in both types of oral samples. Using LEfSe and DESeq2 analyses, we found differentially abundant genera that may be potential biomarkers for each group. Mogibacterium is the predominant genus in COPD. Ten genera, including Desulfovibrio, Filifactor, Fretibacterium, Moraxella, Odoribacter, Pseudoramibacter Pyramidobacter, Scardovia, Shuttleworthia and Treponema were predominant in periodontitis. Bergeyella, Lautropia, Rothia, Propionibacterium and Cardiobacterium were the signature of the healthy controls. The significantly different pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG) between healthy controls and other groups were concentrated in genetic information processing, translation, replication and repair, and metabolism of cofactors and vitamins.

Conclusions

We found the significant differences in the bacterial community and functional characterization of oral microbiota in periodontitis, COPD and comorbid diseases. Compared to gingival crevicular fluid, subgingival plaque may be more appropriate for reflecting the difference of subgingival microbiota in periodontitis patients with COPD. These results may provide potentials for predicting, screening, and treatment strategies for individuals with periodontitis and COPD.

Inonotus hispidus Protects against Hyperlipidemia by Inhibiting Oxidative Stress and Inflammation through Nrf2/NF-κB Signaling in High Fat Diet Fed Mice

Obesity is frequently associated with dysregulated lipid metabolism and lipotoxicity. Inonotus hispidus (Bull.: Fr.) P. Karst (IH) is an edible and medicinal parasitic mushroom. In this study, after a systematic analysis of its nutritional ingredients, the regulatory effects of IH on lipid metabolism were investigated in mice fed a high-fat diet (HFD). In HFD-fed mice, IH reversed the pathological state of the liver and the three types of fat and significantly decreased the levels of low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglycerides (TG), and leptin (LEP) and increased the level of high-density liptein cholesterol (HDL-C) in serum. Meanwhile, IH ameliorated liver damage by reducing alanine aminotransferase (ALT), aspartate aminotransferase (AST), interleukin (IL)-1β, IL-6, tumor necrosis factor-alpha (TNF-α), and plasminogen activator inhibitor-1 (PAI-1) levels in the liver and serum. Compared with HFD-fed mice, IH significantly modulated the gut microbiota, changed the relative abundances of microflora at different taxonomic levels, and regulated lipid levels. The results showed that 30 differential lipids were found. Results from Western blotting confirmed that IH regulated the nuclear factor erythroid-2 related factor 2 (Nrf2)/nuclear factor-kappa B (NF-κB) signaling pathway and oxidative stress. This study aimed to provide experimental evidence for the applicability of IH in obesity treatment.

Saliva microbiome changes in thyroid cancer and thyroid nodules patients

Objective

Thyroid disease has been reported to associate with gut microbiota, but the effects of thyroid cancer and thyroid nodules on the oral microbiota are still largely unknown. This study aimed to identify the variation in salivary microbiota and their potential association with thyroid cancer and thyroid nodules.

Methods

We used 16S rRNA high-throughput sequencing to examine the salivary microbiota of thyroid cancer patients (n = 14), thyroid nodules patients (n = 9), and healthy controls (n = 15).

Results

The alpha-diversity indices Chao1 and ACE were found to be relatively higher in patients with thyroid cancer and thyroid nodules compared to healthy controls. The beta diversity in both the thyroid cancer and thyroid nodules groups was divergent from the healthy control group. The genera Alloprevotella, Anaeroglobus, Acinetobacter, unclassified Bacteroidales, and unclassified Cyanobacteriales were significantly enriched in the thyroid cancer group compared with the healthy control group. In contrast, the microbiome of the healthy controls was mainly composed of the genera Haemophilus, Lautropia, Allorhizobium Neorhizobium Pararhizobium Rhizobium, Escherichia Shigella, and unclassified Rhodobacteraceae. The thyroid nodules group was dominated by genre uncultured Candidatus Saccharibacteria bacterium, unclassified Clostridiales bacterium feline oral taxon 148, Treponema, unclassified Prevotellaceae, Mobiluncus, and Acholeplasma. In contrast, the genera unclassified Rhodobacteraceae and Aggregatibacter dominated the healthy control group. The study also found that clinical indicators were correlated with the saliva microbiome.

Conclusion

The salivary microbiota variation may be connected with thyroid cancer and thyroid nodules.

Metagenomic and Metatranscriptomic Insight Into Oral Biofilms in Periodontitis and Related Systemic Diseases

The oral microbiome is one of the most complex microbial communities in the human body and is closely related to oral and systemic health. Dental plaque biofilms are the primary etiologic factor of periodontitis, which is a common chronic oral infectious disease. The interdependencies that exist among the resident microbiota constituents in dental biofilms and the interaction between pathogenic microorganisms and the host lead to the occurrence and progression of periodontitis. Therefore, accurately and comprehensively detecting periodontal organisms and dissecting their corresponding functional activity characteristics are crucial for revealing periodontitis pathogenesis. With the development of metagenomics and metatranscriptomics, the composition and structure of microbial communities as well as the overall functional characteristics of the flora can be fully profiled and revealed. In this review, we will critically examine the currently available metagenomic and metatranscriptomic evidence to bridge the gap between microbial dysbiosis and periodontitis and related systemic diseases.