Importance of Virulence Factors for the Persistence of Oral Bacteria in the Inflamed Gingival Crevice and in the Pathogenesis of Periodontal Disease

The root canal microbiome diversity and function. A whole-metagenome shotgun analysis

AIM

To evaluate the root canal microbiome composition and bacterial functional capability in cases of primary and secondary apical periodontitis utilizing whole-metagenome shotgun sequencing.

METHODOLOGY

Twenty-two samples from patients with primary root canal infections, and 18 samples obtained from previously treated teeth currently diagnosed with apical periodontitis were analysed with whole-metagenome shotgun sequencing at a depth of 20 M reads. Taxonomic and functional gene annotations were made using MetaPhlAn3 and HUMAnN3 software. The Shannon and Chao1 indices were utilized to measure alpha diversity. Differences in community composition were evaluated utilizing analysis of similarity (ANOSIM) using Bray-Curtis dissimilarities. The Wilcoxon rank sum test was used to compare differences in taxa and functional genes.

RESULTS

Microbial community variations within a community were significantly lower in secondary relative to primary infections (alpha diversity p = .001). Community composition was significantly different in primary versus secondary infection (R = .11, p = .005). The predominant taxa observed among samples (>2.5%) were Pseudopropionibacterium propionicum, Prevotella oris, Eubacterium infirmum, Tannerella forsythia, Atopobium rimae, Peptostreptococcus stomatis, Bacteroidetes bacterium oral taxon 272, Parvimonas micra, Olsenella profusa, Streptococcus anginosus, Lactobacillus rhamnosus, Porphyromonas endodontalis, Pseudoramibacter alactolyticus, Fusobacterium nucleatum, Eubacterium brachy and Solobacterium moorei. The Wilcoxon rank test revealed no significant differences in relative abundances of functional genes in both groups. Genes with greater relative abundances (top 25) were associated with genetic, signalling and cellular processes including the iron and peptide/nickel transport system. Numerous genes encoding toxins were identified: exfoliative toxin, haemolysins, thiol-activated cytolysin, phospholipase C, cAMP factor, sialidase, and hyaluronic glucosaminidase.

CONCLUSIONS

Despite taxonomic differences between primary and secondary apical periodontitis, the functional capability of the microbiomes was similar.

The escalating threat of human-associated infectious bacteria in surface aquatic resources: Insights into prevalence, antibiotic resistance, survival mechanisms, detection, and prevention strategies

Anthropogenic activities and climate change profoundly impact water quality, leading to a concerning increase in the prevalence and abundance of bacterial pathogens across diverse aquatic environments. This rise has resulted in a growing challenge concerning the safety of water sources, particularly surface waters and marine environments. This comprehensive review delves into the multifaceted challenges presented by bacterial pathogens, emphasizing threads to human health within ground and surface waters, including marine ecosystems. The exploration encompasses the intricate survival mechanisms employed by bacterial pathogens and the proliferation of antimicrobial resistance, largely driven by human-generated antibiotic contamination in aquatic systems. The review further addresses prevalent pathogenic bacteria, elucidating associated risk factors, exploring their eco-physiology, and discussing the production of potent toxins. The spectrum of detection techniques, ranging from conventional to cutting-edge molecular approaches, is thoroughly examined to underscore their significance in identifying and understanding waterborne bacterial pathogens. A critical aspect highlighted in this review is the imperative for real-time monitoring of biomarkers associated with waterborne bacterial pathogens. This monitoring serves as an early warning system, facilitating the swift implementation of action plans to preserve and protect global water resources. In conclusion, this comprehensive review provides fresh insights and perspectives, emphasizing the paramount importance of preserving the quality of aquatic resources to safeguard human health on a global scale.

Dental Stem Cells and Lipopolysaccharides: A Concise Review

Dental tissue stem cells (DTSCs) are well known for their multipotent capacity and regenerative potential. They also play an important role in the immune response of inflammatory processes derived from caries lesions, periodontitis, and gingivitis. These oral diseases are triggered by toxins known as lipopolysaccharides (LPS) produced by gram-negative bacteria. LPS present molecular patterns associated with pathogens and are recognized by Toll-like receptors (TLRs) in dental stem cells. In this review, we describe the effect of LPS on the biological behavior of DTSCs. We also focus on the molecular sensors, signaling pathways, and emerging players participating in the interaction of DTSCs with lipopolysaccharides. Although the scientific advances generated provide an understanding of the immunomodulatory potential of DTSCs, there are still new reflections to explore with regard to their clinical application in the treatment of oral inflammatory diseases.

Biomaterials Functionalized with Inflammasome Inhibitors-Premises and Perspectives

This review aimed at searching literature for data regarding the inflammasomes' involvement in the pathogenesis of oral diseases (mainly periodontitis) and general pathologies, including approaches to control inflammasome-related pathogenic mechanisms. The inflammasomes are part of the innate immune response that activates inflammatory caspases by canonical and noncanonical pathways, to control the activity of Gasdermin D. Once an inflammasome is activated, pro-inflammatory cytokines, such as interleukins, are released. Thus, inflammasomes are involved in inflammatory, autoimmune and autoinflammatory diseases. The review also investigated novel therapies based on the use of phytochemicals and pharmaceutical substances for inhibiting inflammasome activity. Pharmaceutical substances can control the inflammasomes by three mechanisms: inhibiting the intracellular signaling pathways (Allopurinol and SS-31), blocking inflammasome components (VX-765, Emricasan and VX-740), and inhibiting cytokines mediated by the inflammasomes (Canakinumab, Anakinra and Rilonacept). Moreover, phytochemicals inhibit the inflammasomes by neutralizing reactive oxygen species. Biomaterials functionalized by the adsorption of therapeutic agents onto different nanomaterials could represent future research directions to facilitate multimodal and sequential treatment in oral pathologies.

An Overview of Biofilm-Associated Infections and the Role of Phytochemicals and Nanomaterials in Their Control and Prevention

Biofilm formation is considered one of the primary virulence mechanisms in Gram-positive and Gram-negative pathogenic species, particularly those responsible for chronic infections and promoting bacterial survival within the host. In recent years, there has been a growing interest in discovering new compounds capable of inhibiting biofilm formation. This is considered a promising antivirulence strategy that could potentially overcome antibiotic resistance issues. Effective antibiofilm agents should possess distinctive properties. They should be structurally unique, enable easy entry into cells, influence quorum sensing signaling, and synergize with other antibacterial agents. Many of these properties are found in both natural systems that are isolated from plants and in synthetic systems like nanoparticles and nanocomposites. In this review, we discuss the clinical nature of biofilm-associated infections and some of the mechanisms associated with their antibiotic tolerance. We focus on the advantages and efficacy of various natural and synthetic compounds as a new therapeutic approach to control bacterial biofilms and address multidrug resistance in bacteria.

Nisin lantibiotic prevents NAFLD liver steatosis and mitochondrial oxidative stress following periodontal disease by abrogating oral, gut and liver dysbiosis

Oral microbiome dysbiosis mediates chronic periodontal disease, gut microbial dysbiosis, and mucosal barrier disfunction that leads to steatohepatitis via the enterohepatic circulation. Improving this dysbiosis towards health may improve liver disease. Treatment with antibiotics and probiotics have been used to modulate the microbial, immunological, and clinical landscape of periodontal disease with some success. The aim of the present investigation was to evaluate the potential for nisin, an antimicrobial peptide produced by Lactococcus lactis, to counteract the periodontitis-associated gut dysbiosis and to modulate the glycolipid-metabolism and inflammation in the liver. Periodontal pathogens, namely Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia and Fusobacterium nucleatum, were administrated topically onto the oral cavity to establish polymicrobial periodontal disease in mice. In the context of disease, nisin treatment significantly shifted the microbiome towards a new composition, commensurate with health while preventing the harmful inflammation in the small intestine concomitant with decreased villi structural integrity, and heightened hepatic exposure to bacteria and lipid and malondialdehyde accumulation in the liver. Validation with RNA Seq analyses, confirmed the significant infection-related alteration of several genes involved in mitochondrial dysregulation, oxidative phosphorylation, and metal/iron binding and their restitution following nisin treatment. In support of these in vivo findings indicating that periodontopathogens induce gastrointestinal and liver distant organ lesions, human autopsy specimens demonstrated a correlation between tooth loss and severity of liver disease. Nisin's ability to shift the gut and liver microbiome towards a new state commensurate with health while mitigating enteritis, represents a novel approach to treating NAFLD-steatohepatitis-associated periodontal disease.

The expression levels of chemotaxis-related molecules CXC chemokine receptor 1, interleukin-8, and pro-platelet basic protein in gingival tissues

Background/purpose

Excessive host immune response is thought to be an important cause of periodontal tissue damage during periodontitis. The potent chemotaxis produced by locally released chemokines is the key signal to trigger this response. Here, we aimed to investigate the expression of CXC chemokine receptor 1 (CXCR1), and chemokines interleukin-8 (IL-8) and pro-platelet basic protein (PPBP) in human inflammatory gingival tissues compared with healthy tissues.

Materials and methods

A total of 54 human gingival tissues, 27 healthy and 27 inflammatory samples, were collected. Fifteen specimens of each group were employed for quantitative reverse transcription polymerase chain reaction to determine the mRNA levels of CXCR1, IL-8, and PPBP. Six samples of each group were used for Western blotting to investigate the protein expression of CXCR1 and for enzyme-linked immunosorbent assay to evaluate the protein levels of IL-8 and PPBP, respectively.

Results

The mRNA levels of chemokine receptor CXCR1, chemokine IL-8, and PPBP in inflammatory gingival tissues were significantly higher than those in healthy controls (P < 0.05). The protein levels of CXCR1, IL-8, and PPBP in inflammatory gingival tissues were also significantly higher than those in healthy gingival tissues (P < 0.05).

Conclusion

When compared to healthy gingival tissues, the expression of CXCR1, IL-8, and PPBP in inflammatory gingival tissues is higher.

Cytological and microbiological investigations of professional hygiene efficiency in patients with generalized periodontitis

OBJECTIVE

Aim: The purpose of this study is to assess the impact of occupational hygiene procedures for microbiological and cytological contents of periodontal pockets.

PATIENTS AND METHODS

Material and Methods: Cytological and microbiological content of the periodontal pockets before treatment and after professional hygiene procedures including scaling with hand instruments and root cementum polishing have been investigated in patients with periodontitis.

RESULTS

Results: According to obtained data it can be resumed that in periodontitis patients with the depth of pockets 3-5,5 mm before professional hygiene all the pockets contain great number of Cocci, Spirochetes, Candida Albicans, Flagellated rods and Protozoa species. It was proved by revealing of small amount of Polymorphonuclear leukocytes with active phagocytosis. After scaling and planing of the roots, a decrease in the number of Protozoa and Candida Albicans was observed in 97% and 72% of the investigated cells, respectively.

CONCLUSION

Conclusions: Cytological and microbiological content of periodontal pockets before treatment and after professional hygiene procedures including scaling and root planning testify to the level of local protective mechanisms, especially process of phagocytosis and virulence of microbial species in periodontal pockets.

Current concepts in the pathogenesis of periodontitis: from symbiosis to dysbiosis

The primary etiological agent for the initiation and progression of periodontal disease is the dental plaque biofilm which is an organized aggregation of microorganisms residing within a complex intercellular matrix. The non-specific plaque hypothesis was the first attempt to explain the role of the dental biofilm in the pathogenesis of periodontal diseases. However, the introduction of sophisticated diagnostic and laboratory assays has led to the realisation that the development of periodontitis requires more than a mere increase in the biomass of dental plaque. Indeed, multispecies biofilms exhibit complex interactions between the bacteria and the host. In addition, not all resident microorganisms within the biofilm are pathogenic, since beneficial bacteria exist that serve to maintain a symbiotic relationship between the plaque microbiome and the host’s immune-inflammatory response, preventing the emergence of pathogenic microorganisms and the development of dysbiosis. This review aims to highlight the development and structure of the dental plaque biofilm and to explore current literature on the transition from a healthy (symbiotic) to a diseased (dysbiotic) biofilm in periodontitis and the associated immune-inflammatory responses that drive periodontal tissue destruction and form mechanistic pathways that impact other systemic non-communicable diseases.

Dysbiosis of oral microbiome persists after dental treatment-induced remission of periodontal disease and dental caries

IMPORTANCE

We characterized the oral conditions, salivary microbiome, and metabolome after dental treatment by investigating the state after treatment completion and transition to self-care. Dental treatment improved oral health conditions, resulting in oral disease remission; however, the imbalanced state of the salivary microbiome continued even after remission. Although the results of this study are preliminary, owing to the small number of participants in each group when compared to larger cohort studies, they indicate that the risk of disease may remain higher than that of healthy participants, thereby demonstrating the importance of removing dental plaque containing disease-related bacteria using appropriate care even after treatment completion. We also identified bacterial species with relative abundances that differed from those of healthy participants even after remission of symptoms, which may indicate that the maturation of certain bacterial species must be controlled to improve the oral microbiome and reduce the risk of disease recurrence.

Sensors for in situ monitoring of oral and dental health parameters in saliva

OBJECTIVES

The oral cavity is an easily accessible unique environment and open system which is influenced by the oral fluids, microbiota, and nutrition. Little is known about the kinetics and dynamics of metabolic processes at the intraoral surfaces. Real-time monitoring of salivary biomarkers, e.g., glucose, lactate, fluoride, calcium, phosphate, and pH with intraoral sensors is therefore of major interest. The aim of this review is to overview the existing literature for intraoral saliva sensors.

MATERIALS AND METHODS

A comprehensive literature search was performed to review the most relevant studies on intraoral saliva sensor technology.

RESULTS

There is limited literature about the in situ saliva monitoring of salivary biomarkers. Bioadhesion and biofouling processes at the intraoral surfaces limit the performances of the sensors. Real-time, long-term, and continuous intraoral measurement of salivary metabolites remains challenging and needs further investigation as only few well-functioning sensors have been developed until today. Until now, there is no sensor that measures reliably beyond hours for any analyte other than glucose.

CONCLUSIONS

Saliva's complex and dynamic structure as well as bioadhesion are key challenges and should be addressed in the future developments. Consequently, more studies that focus particularly on biofouling processes and interferential effects of the salivary matrix components on sensor surfaces are required.

CLINICAL RELEVANCE

By monitoring fluids in the oral cavity, as the entrance to the digestive system, extensive information can be obtained regarding the effects of foods and preventive agents on the oral microbiota and the tooth surfaces. This may lead to a better understanding of strategies to modulate oral and general health.

Multiplexed LC-MS/MS quantification of salivary RNA modifications in periodontitis

OBJECTIVE

To analyse the salivary epitranscriptomic profiles as periodontitis biomarkers using multiplexed mass spectrometry (MS).

BACKGROUND

The field of epitranscriptomics, which relates to RNA chemical modifications, opens new perspectives in the discovery of diagnostic biomarkers, especially in periodontitis. Recently, the modified ribonucleoside N6-methyladenosine (m6A) was revealed as a crucial player in the etiopathogenesis of periodontitis. However, no epitranscriptomic biomarker has been identified in saliva to date.

MATERIALS AND METHODS

Twenty-four saliva samples were collected from periodontitis patients (n = 16) and from control subjects (n = 8). Periodontitis patients were stratified according to stage and grade. Salivary nucleosides were directly extracted and, in parallel, salivary RNA was digested into its constituent nucleosides. Nucleoside samples were then quantified by multiplexed MS.

RESULTS

Twenty-seven free nucleosides were detected and an overlapping set of 12 nucleotides were detected in digested RNA. Among the free nucleosides, cytidine and three other modified nucleosides (inosine, queuosine and m6Am) were significantly altered in periodontitis patients. In digested RNA, only uridine was significantly higher in periodontitis patients. Importantly there was no correlation between free salivary nucleoside levels and the levels of those same nucleotides in digested salivary RNA, except for cytidine, m5C and uridine. This statement implies that the two detection methods are complementary.

CONCLUSION

The high specificity and sensitivity of MS allowed the detection and quantification of multiple nucleosides from RNA and free nucleosides in saliva. Some ribonucleosides appear to be promising biomarkers of periodontitis. Our analytic pipeline opens new perspectives for diagnostic periodontitis biomarkers.

Porphyromonas gingivalis Peptidyl Arginine Deiminase (PPAD) in the Context of the Feed-Forward Loop of Inflammation in Periodontitis

Periodontitis is a widespread chronic inflammatory disease caused by a changed dysbiotic oral microbiome. Although multiple species and risk factors are associated with periodontitis, Porphyromonas gingivalis has been identified as a keystone pathogen. The immune-modulatory function of P. gingivalis is well characterized, but the mechanism by which this bacterium secretes peptidyl arginine deiminase (PPAD), a protein/peptide citrullinating enzyme, thus contributing to the infinite feed-forward loop of inflammation, is not fully understood. To determine the functional role of citrullination in periodontitis, neutrophils were stimulated by P. gingivalis bearing wild-type PPAD and by a PPAD mutant strain lacking an active enzyme. Flow cytometry showed that PPAD contributed to prolonged neutrophil survival upon bacterial stimulation, accompanied by the secretion of aberrant IL-6 and TNF-α. To further assess the complex mechanism by which citrullination sustains a chronic inflammatory state, the ROS production and phagocytic activity of neutrophils were evaluated. Flow cytometry and colony formation assays showed that PPAD obstructs the resolution of inflammation by promoting neutrophil survival and the release of pro-inflammatory cytokines, while enhancing the resilience of the bacteria to phagocytosis.

Oral squamous carcinoma cell lysates provoke exacerbated inflammatory response in gingival fibroblasts

OBJECTIVES

To study whether damaged epithelial cells and gingival fibroblast could affect the expression of inflammatory cytokines in healthy cells.

MATERIALS AND METHODS

Cell suspensions were submitted to different treatments to obtain the lysates: no treatment (supernatant control), sonication, and freeze/thawing. All treatments were centrifuged, and the supernatants of the lysates were used for experimentation. Cell viability assays, RT-qPCR of IL1, IL6 and IL8, IL6 immunoassay, and immunofluorescence of NF-kB p65 were applied to verify the inflammatory crosstalk of damaged cells over healthy plated cells. Furthermore, titanium discs and collagen membranes were treated with lysates and checked for IL8 expression by RT-qPCR.

RESULTS

Lysates obtained upon sonication or freeze/thawing of oral squamous carcinoma cell lines provoked a robust increase in the expression of IL1, IL6, and IL8 by gingival fibroblasts, which was confirmed by IL6 immunoassays. Lysates obtained from the gingival fibroblasts failed to increase the expression of inflammatory cytokines in oral squamous carcinoma cells. Additionally, oral squamous carcinoma cell lysates caused the activation of the NF-kB signalling cascade in gingival fibroblasts as indicated by the phosphorylation and nuclear translocation of p65. Finally, oral squamous carcinoma cell lysates adhered to the titanium and collagen membrane surfaces and increased IL8 expression by gingival fibroblasts growing in these materials.

CONCLUSIONS

Injured oral epithelial cells can release factors that incite gingival fibroblasts to become pro-inflammatory.

CLINICAL RELEVANCE

Injuries affecting the oral mucosa generate epithelial fragments that may reach the underlying connective tissue and provoke inflammation. These injuries are routinely caused by mastication, sonication for teeth cleaning, teeth preparation, prostheses maladaptation, and implant drilling.

Gingival Tissue MiRNA Expression Profiling and an Analysis of Periodontitis-Specific Circulating MiRNAs

This study aimed to identify the microRNAs (miRNAs) associated with periodontitis (PD) in gingival tissues, and to evaluate the levels of these selected miRNAs in the saliva and blood plasma among participants with and without rheumatoid arthritis (RA). A genome-wide miRNA expression analysis in 16 gingival tissue samples revealed 177 deregulated miRNAs. The validation of the miRNA profiling results in 80 gingival tissue samples revealed that the PD-affected tissues had a higher expression of miR-140-3p and -145-5p, while the levels of miR-125a-3p were significantly lower in inflamed tissues. After a thorough validation, four miRNAs, namely miR-140-3p, -145-5p, -146a-5p, and -195-5p, were selected for further analysis in a larger sample of salivary (N = 173) and blood plasma (N = 221) specimens. Increased salivary levels of miR-145-5p were associated with higher mean values of pocket probing depth and bleeding on probing index. The plasma-derived levels of miR-140-3p were higher among the participants with PD. In conclusion, the gingival levels of miR-140-3p, -145-5p, and -125a-3p were independently associated with PD presence and severity. The salivary and blood plasma levels of the target miRNAs were diversely related to PD. Similar miRNA associations with PD were observed among the participants with and without RA.

Treatment of Periodontal Infections, the Possible Role of Hydrogels as Antibiotic Drug-Delivery Systems

With the advancement of biomedical research into antimicrobial treatments for various diseases, the source and delivery of antibiotics have attracted attention. In periodontal diseases, antibiotics are integral in positive treatment outcomes; however, the use of antibiotics is with caution as the potential for the emergence of resistant strains is of concern. Over the years, conventional routes of drug administration have been proven to be effective for the treatment of PD, yet the problem of antibiotic resistance to conventional therapies continues to remain a setback in future treatments. Hydrogels fabricated from natural and synthetic polymers have been extensively applied in biomedical sciences for the delivery of potent biological compounds. These polymeric materials either have intrinsic antibacterial properties or serve as good carriers for the delivery of antibacterial agents. The biocompatibility, low toxicity and biodegradability of some hydrogels have favoured their consideration as prospective carriers for antibacterial drug delivery in PD. This article reviews PD and its antibiotic treatment options, the role of bacteria in PD and the potential of hydrogels as antibacterial agents and for antibiotic drug delivery in PD. Finally, potential challenges and future directions of hydrogels for use in PD treatment and diagnosis are also highlighted.

"Medicine food homology" plants promote periodontal health: antimicrobial, anti-inflammatory, and inhibition of bone resorption

"Medicine food homology" (MFH) is a term with a lengthy history. It refers to the fact that a lot of traditional natural products have both culinary and therapeutic benefits. The antibacterial, anti-inflammatory and anticancer effects of MFH plants and their secondary metabolites have been confirmed by numerous research. A bacterially generated inflammatory illness with a complicated pathophysiology, periodontitis causes the loss of the teeth's supporting tissues. Several MFH plants have recently been shown to have the ability to prevent and treat periodontitis, which is exhibited by blocking the disease's pathogens and the virulence factors that go along with them, lowering the host's inflammatory reactions and halting the loss of alveolar bone. To give a theoretical foundation for the creation of functional foods, oral care products and adjuvant therapies, this review has especially explored the potential medicinal benefit of MFH plants and their secondary metabolites in the prevention and treatment of periodontitis.

Microbial metabolites in the pathogenesis of periodontal diseases: a narrative review

The purpose of this narrative review is to highlight the importance of microbial metabolites in the pathogenesis of periodontal diseases. These diseases, involving gingivitis and periodontitis are inflammatory conditions initiated and maintained by the polymicrobial dental plaque/biofilm. Gingivitis is a reversible inflammatory condition while periodontitis involves also irreversible destruction of the periodontal tissues including the alveolar bone. The inflammatory response of the host is a natural reaction to the formation of plaque and the continuous release of metabolic waste products. The microorganisms grow in a nutritious and shielded niche in the periodontal pocket, protected from natural cleaning forces such as saliva. It is a paradox that the consequences of the enhanced inflammatory reaction also enable more slow-growing, fastidious, anaerobic bacteria, with often complex metabolic pathways, to colonize and thrive. Based on complex food chains, nutrient networks and bacterial interactions, a diverse microbial community is formed and established in the gingival pocket. This microbiota is dominated by anaerobic, often motile, Gram-negatives with proteolytic metabolism. Although this alternation in bacterial composition often is considered pathologic, it is a natural development that is promoted by ecological factors and not necessarily a true "dysbiosis". Normal commensals are adapting to the gingival crevice when tooth cleaning procedures are absent. The proteolytic metabolism is highly complex and involves a number of metabolic pathways with production of a cascade of metabolites in an unspecific manner. The metabolites involve short chain fatty acids (SCFAs; formic, acetic, propionic, butyric, and valeric acid), amines (indole, scatole, cadaverine, putrescine, spermine, spermidine) and gases (NH₃, CO, NO, H₂S, H₂). A homeostatic condition is often present between the colonizers and the host response, where continuous metabolic fluctuations are balanced by the inflammatory response. While it is well established that the effect of the dental biofilm on the host response and tissue repair is mediated by microbial metabolites, the mechanisms behind the tissue destruction (loss of clinical attachment and bone) are still poorly understood. Studies addressing the functions of the microbiota, the metabolites, and how they interplay with host tissues and cells, are therefore warranted.

Age-Related Subgingival Colonization of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Parvimonas micra-A Pragmatic Microbiological Retrospective Report

The aim of this study was to compare data about the prevalence and proportions of the bacterial species Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Parvimonas micra in periodontitis pocket samples collected from young, <35 years, and old, >35-year-old patients, YP and OP, respectively. The results from the analyses of a total of 3447 subgingival plaque samples analyzed for clinical diagnosis purposes by cultivation regarding the proportions of these species were collected from a database and elucidated. The prevalence of A. actinomycetemcomitans was found to be more than twice as high (OR = 2.96, 95% CI; 2.50-3.50) in samples from the younger (42.2%) than the older group (20.4%) (p < 0.001). The prevalence of P. micra was significantly lower in samples from the younger age group (OR = 0.43, 95%) (p < 0.001), whereas P. gingivalis was similarly distributed (OR = 0.78, 95%) in the two age groups (p = 0.006). A similar pattern was noticed for A. actinomycetemcomitans and P. gingivalis when high proportions (>50%) of the samples of these bacterial species were elucidated. In contrast, the proportion of samples containing >50% with P. micra was lower compared with the two other bacterial species. Furthermore, it was noted that the proportion of samples from old patients containing A. actinomycetemcomitans in combination with P. micra was almost three times higher than in samples when P. micra was replaced by P. gingivalis. In conclusion, A.actinomycetemcomitans showed an increased presence and proportion in samples from young patients compared with the old patients, while P. gingivalis was similarly distributed in the two age groups. P. micra showed an increased presence and proportion in samples from old patients compared with the young patients.

Persister Cell Formation and Elevated lsrA and lsrC Gene Expression upon Hydrogen Peroxide Exposure in a Periodontal Pathogen Aggregatibacter actinomycetemcomitans

The effect of hydrogen peroxide, an antiseptic dental treatment, on Aggregatibacter actinomycetemcomitans, the main causative agent of localized invasive periodontitis, was investigated. Hydrogen peroxide treatment (0.06%, 4× minimum inhibitory concentration) resulted in the persistence and survival of approximately 0.5% of the bacterial population. The surviving bacteria did not genetically acquire hydrogen peroxide resistance but exhibited a known persister behavior. Sterilization with mitomycin C significantly reduced the number of A. actinomycetemcomitans persister survivors. RNA sequencing of hydrogen peroxide-treated A. actinomycetemcomitans showed elevated expression of Lsr family members, suggesting a strong involvement of autoinducer uptake. In this study, we found a risk of A. actinomycetemcomitans persister residual from hydrogen peroxide treatment and hypothesized associated genetic mechanisms of persister from RNA sequencing.

Antibacterial effect of a gingival patch containing nano-emulsion of red dragon fruit peel extract on Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum assessed in vitro

Background

The most common bacteria causing periodontitis were Porphyromonas gingivalis, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans. At present, plants are considered a valuable source of natural materials for use in the development of antimicrobial, anti-inflammatory and antioxidant agents. Hylocereus plyrhizus or red dragon fruit peel extract (RDFPE) contains terpenoids, and flavonoids can be an alternative. The gingival patch (GP) has been designed to ensure drug delivery and absorption into tissue targets.

Objective

To assess the effect of a mucoadhesive gingival patch containing nano-emulsion of red dragon fruit peel extract (GP-nRDFPE) in inhibiting Porphyromonas gingivalis, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans as compared to control groups.

Material and method

Inhibition by diffusion method was carried out in Porphyromonas gingivalis, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans medium. The test material was gingival patch mucoadhesive containing nano-emulsion red dragon fruit peel extract (GP-nRDFPR), gingival patch mucoadhesive containing red dragon fruit peel extract (GP-RDFPE), gingival patch mucoadhesive containing doxycycline (GP-dcx) and blank gingival patch (GP), conducted in four replications. The differences in the inhibition were analyzed using ANOVA and post hoc tests (p < 0.05).

Result

GP-nRDFPE showed higher inhibition in Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum compared to GP-RDFPE at the concentrations 3.125% and 6.25% (p < 0.05).

Conclusion

The GP-nRDFPE showed better anti-periodontic bacteria to Porphyromonas gingivalis, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans in line with its concentration. This is assumed that the GP-nRDFPE can use as periodontitis treatment.

Significance of salivary poly (ADP-ribose)-polymerase in the assessment of age-dependent pathological processes in the oral cavity

Age-related changes in the oral cavity are accompanied by the development of age-related pathology, such as chronic periodontitis (CP). Although apoptosis plays a certain role in its pathogenesis, this fact, however, has not been evaluated clinically, and the diagnostic information content of biomarkers of apoptosis and aging has not been determined. The aim of the study was to evaluate the content of cleaved poly-(ADP-ribose)-polymerase (cPARP) and caspase-3 (Casp3) in mixed saliva of elderly patients with age-related dental diseases and in mature patients with mild to moderate CP. The study included 69 people. The control group included 22 healthy young volunteers aged 18 to 44 years. The main group included 22 elderly patients aged 60 to 74 years. They were divided into subgroups according to clinical manifestations: occlusion (comparison group), periodontal, and dystrophic syndromes. Additionally, a group of 25 patients of mature age from 45 to 59 years old with mild to moderate CP was analyzed. The content of salivary Casp3 in patients with occlusion syndrome was lower than in healthy young people (p=0.014). In patients with the periodontal syndrome, the content of cPARP was higher than in the comparison group (p=0.031). The group with dystrophic syndrome had the highest level of Casp3 in comparison with the control group and the comparison group (p=0.012, p=0.004, respectively). There were no statistically significant differences between patients of different age groups with mild to moderate CP. Evaluation of the correlation between cPARP and Casp3 levels revealed a direct relationship in the group of elderly patients and in patients with mild CP (r=0.69, r=0.81, respectively). We assessed the effect of Casp3 levels on changes in the cPARP levels by means of a simple linear regression analysis. The cPARP level correlated with the content of Casp3 (r²=0.555). According to the results of the ROC analysis, it was found that using the cPARP indicator it would be possible to distinguish between groups of elderly patients with periodontal and occlusion syndromes (AUC=0.71), while using Casp3 it would be possible to distinguish patients with the occlusion syndrome and the control group (AUC=0.78). Since the level of Casp3 in young people is significantly higher than in the elderly patients, its decrease can be considered as a potential salivary biomarker of aging. The level of studied cPARP in the elderly has clinical value in periodontal syndrome and low age dependence.

High Virulence and Multidrug Resistance of Escherichia coli Isolated in Periodontal Disease

Periodontal disease is caused by different gram-negative anaerobic bacteria; however, Escherichia coli has also been isolated from periodontitis and its role in periodontitis is less known. This study aimed to determine the variability in virulence genotype, antibiotic resistance phenotype, biofilm formation, phylogroups, and serotypes in different emerging periodontal strains of Escherichia coli, isolated from patients with periodontal disease and healthy controls. E. coli, virulence genes, and phylogroups, were identified by PCR, antibiotic susceptibility by the Kirby-Bauer method, biofilm formation was quantified using polystyrene microtiter plates, and serotypes were determined by serotyping. Although E. coli was not detected in the controls (n = 70), it was isolated in 14.7% (100/678) of the patients. Most of the strains (n = 81/100) were multidrug-resistance. The most frequent adhesion genes among the strains were fimH and iha, toxin genes were usp and hlyA, iron-acquisition genes were fyuA and irp2, and protectin genes were ompT, and KpsMT. Phylogroup B2 and serotype O25:H4 were the most predominant among the strains. These findings suggest that E. coli may be involved in periodontal disease due to its high virulence, multidrug-resistance, and a wide distribution of phylogroups and serotypes.

Growth of Porphyromonas gingivalis on human serum albumin triggers programmed cell death

Aims

Gingival crevicular fluid (GCF) constitutes the primary growth substrate for Porphyromonas gingivalis in vivo. The goal of this work was to evaluate the growth of different strains of P. gingivalis on human serum albumin (HSA), a major constituent of GCF.

Methods

Growth of five different strains of P. gingivalis in the HSA medium was examined and, surprisingly, three of the strains underwent autolysis within 24 h. Comparative transcriptomic analysis was used to identify genes involved in autolysis.

Results

Two highly related reference strains (W50 and W83) differed dramatically in their survival when grown on HSA. Strain W83 grew fast and lysed within 24 h, while W50 survived for an additional 20 h. Differential gene expression analysis led us to a gene cluster containing enzymes involved in arginine metabolism and a gene predicted to be lytic murein transglycosylase, which are known to play a role in autolysis. Deletion of this gene (PG0139) resulted in a mutant that did not lyse, and complementation restored the HSA lysis phenotype, indicating that this enzyme plays a central role in the autolysis of P. gingivalis.

Conclusions

P. gingivalis undergoes autolysis when provided with HSA as a substrate for growth.

Natural polyphenol self-assembled pH-responsive nanoparticles loaded into reversible hydrogel to inhibit oral bacterial activity

Periodontitis is one of the most prevalent chronic inflammatory diseases and Polyphenols isolated from Turkish gall play a major role in the treatment of inflammatory diseases for their antibacterial, anti-inflammatory and antioxidant activities. In this work, Turkish Galls effective constituent (TGEC, T) was prepared into nanoparticles (T-NPs) by principle of oxidative self-polymerization. The pH-sensitive T-NPs was encapsulated into thermosensitive type in-situ hydrogel, and 42.29 ± 1.12% of effective constituent from T-NPs were continuously released within 96 h under the periodontitis environment. In addition, the weakly alkaline oral micro-environment of patients with periodontitis is more conducive to the sustained release of effective constituent, which is 10.83% more than that of healthy periodontal environment. The bacteriostatic test showed that T-NPs had stronger antibacterial activity on oral pathogens than that of TGEC. Compared with TGEC, the minimum inhibitory concentration (MIC) of T-NPs against P. gingivalis and A. viscosus was reduced by 50% and 25%, respectively. Interestingly, T-NPs induced bacteria lysis by promoting the excessive production of ROS without periodontal tissue damage caused by excessive oxidation reaction. In conclusion, a simple method of preparing microspheres with natural polyphenols was developed, which provides beneficial reference for one-step prepared drug carriers from effective components of natural product, likewise the method offers a green and effective solution to synthesis a new adjuvant therapy drugs for treatment of gingivitis associated with periodontal pockets.

In Vitro Antimicrobial Effect of Novel Electrospun Polylactic Acid/Hydroxyapatite Nanofibres Loaded with Doxycycline

The present study aimed to assess the in vitro antimicrobial effects of a novel biomaterial containing polylactic acid (PLA), nano-hydroxyapatite (nano-HAP) and Doxycycline (Doxy) obtained by electrospinning and designed for the non-surgical periodontal treatment. The antimicrobial activity of two samples (test sample, PLA-HAP-Doxy7: 5% PLA, nano-HAP, 7% Doxy and control sample, PLA-HAP: 5% PLA, nano-HAP) against two periodontal pathogens—Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis—was assessed using the Kirby−Bauer Disk Diffusion Susceptibility Test and compared with the effect of four antibiotics used as adjuvants in periodontal therapy: Amoxicillin, Ampicillin, Doxy and Metronidazole. The test sample (embedded with Doxy) showed higher inhibitory effects than commonly used antibiotics used in the treatment of periodontitis, while the control sample showed no inhibitory effects. Moreover, significant differences were observed between the inhibition zones of the two samples (p < 0.05). The Doxy-loaded PLA nanofibres had an antimicrobial effect against the periodontal pathogens. Based on these results, the novel biomaterial could be a promising candidate as adjuvant for the non-surgical local treatment in periodontitis.

Association between BMI and periodontitis in women living with or at risk for HIV

AIMS

Currently, there is no data available assessing the association between body mass index (BMI) and periodontitis among women living with HIV (WLWH). This study aims to investigate this association among WLWH and women at risk for HIV (WRH) in the United States.

METHODS AND RESULTS

Data from 351 WLWH and 52 WRH participants from the Women's Interagency HIV Study having pocket depths and clinical periodontal attachment loss assessments in 2003-2004 were included. Multinomial logistic regression analyses in the full sample assessed the relationship between BMI (underweight/normal, overweight, or obese) and periodontitis by severity (mild, moderate, severe), adjusting for study sites, age, education, annual household income, smoking, alcohol consumption, and diabetes. Overall, 75.2% women (76.0% WLWH; 69.0% WRH) had periodontitis. Moreover, 75.0% obese and 75.3% overweight women were affected by periodontitis. In the full sample, adjusted odds ratio (aOR) of having mild, moderate, and severe periodontitis in obese women were: 1.14 (95% confidence interval [CI]: 0.51-2.52), 1.02 (95% CI: 0.46-2.29), and 0.24 (95% CI: 0.06-1.07), respectively, and in overweight women: 0.70 (95% CI: 0.31-1.58), 0.85 (95% CI: 0.38-1.90), and 0.31 (95% CI: 0.08-1.15), respectively.

CONCLUSIONS

Even with high prevalence of periodontitis among women with or without HIV infection in this cohort, this study does not provide evidence of an association between BMI and periodontitis.

Aggregatibacter actinomycetemcomitans and Filifactor alocis: Two exotoxin-producing oral pathogens

Periodontitis is a dysbiotic disease caused by the interplay between the microbial ecosystem present in the disease with the dysregulated host immune response. The disease-associated microbial community is formed by the presence of established oral pathogens like Aggregatibacter actinomycetemcomitans as well as by newly dominant species like Filifactor alocis. These two oral pathogens prevail and grow within the periodontal pocket which highlights their ability to evade the host immune response. This review focuses on the virulence factors and potential pathogenicity of both oral pathogens in periodontitis, accentuating the recent description of F. alocis virulence factors, including the presence of an exotoxin, and comparing them with the defined factors associated with A. actinomycetemcomitans. In the disease setting, possible synergistic and/or mutualistic interactions among both oral pathogens might contribute to disease progression.

Periodontal status and the incidence of selected bacterial pathogens in periodontal pockets and vascular walls in patients with atherosclerosis and abdominal aortic aneurysms

The aim of the study was to examine the periodontal status of patients with atherosclerosis and abdominal aortic aneurysms. The occurrence of 5 periodontopathogens was evaluated in periodontal pockets and atheromatous plaques together with specimens from pathologically changed vascular walls of aortic aneurysms. The study comprised 39 patients who qualified for vascular surgeries. Patients with periodontitis and concomitant atherosclerosis or aneurysms were enrolled in the study. Periodontal indices were evaluated, and subgingival plaque samples were examined together with atheromatous plaques or specimens from vascular walls to identify, by polymerase chain reaction (PCR), the following periodontopathogens: Porphyromonas gingivalis, Tanarella forsythia, Aggregatibacter actinomycetemcomitans, Prevotella intermedia and Treponema denticola. The majority of patients had chronic severe generalized periodontitis in stages III and IV. Laboratory investigations showed the occurrence of one or more of the five targeted periodontopathogens in 94.6% of the periodontal pockets examined. Of the examined periodontopathogens, only Porphyromonas gingivalis was confirmed in 1 atheromatous plaque sample collected from the wall of an aortic aneurysm. Therefore, the occurrence of this bacterium in these vessels was considered to be occasional in patients with chronic periodontitis.

Prevotella: An insight into its characteristics and associated virulence factors

Prevotella species, a gram-negative obligate anaerobe, is commonly associated with human infections such as dental caries and periodontitis, as well as other conditions such as chronic osteomyelitis, bite-related infections, rheumatoid arthritis and intestinal diseases like ulcerative colitis. This generally harmless commensal possesses virulence factors such as adhesins, hemolysins, secretion systems exopolysaccharide, LPS, proteases, quorum sensing molecules and antibiotic resistance to evolve into a well-adapted pathogen capable of causing successful infection and proliferation in the host tissue. This review describes several of these virulence factors and their advantage to Prevotella spp. in causing inflammatory diseases like periodontitis. In addition, using genome analysis of Prevotella reference strains, we examined other putative virulence determinants which can provide insights as biomarkers and be the targets for effective interventions in Prevotella related diseases like periodontitis.

Effects of a Berry Polyphenolic Fraction on the Pathogenic Properties of Porphyromonas gingivalis

Porphyromonas gingivalis expresses a broad array of virulence factors that enable it to play a central role in the etiopathogenesis of periodontitis. The objective of the present study was to assess the effects of a berry polyphenolic fraction (Orophenol®) composed of extracts from cranberry, wild blueberry, and strawberry on the main pathogenic determinants of P. gingivalis. Orophenol® attenuated the growth of P. gingivalis and decreased its hemolytic activity, its adherence to a basement membrane matrix model, and its proteinase activities. The berry polyphenolic fraction also impaired the production of reactive oxygen species (ROS) by oral keratinocytes stimulated with P. gingivalis. Lastly, using an in vitro model of oral keratinocyte barrier, the fraction exerted a protective effect against the damages mediated by P. gingivalis. In conclusion, the berry polyphenolic fraction investigated in the present study attenuated several pathogenic properties of P. gingivalis. Although future clinical investigations are required, our study provided evidence that the polyphenols contained in this fraction may represent bioactive molecules of high interest for the prevention and/or treatment of periodontal disease.

mTOR Signaling in the Regulation of CD4+ T Cell Subsets in Periodontal Diseases

Periodontal disease results from the inflammatory infiltration by the microbial community which is marked through tooth mobility and alveolar bone resorption. The inflammation in periodontal disease is mediated by CD4⁺ T cells through cytokine secretion and osteoclastogenetic activity. Historically, the inflammatory model in periodontal disease is described through disruption of the balance between two subsets of T helper cells which are T-helper type 1 (Th1) and T-helper type 2 (Th2). However, more and more studies have found that apart from subsets of helper T cells, regulatory T-cells and Th17 cells are also involved in the pathogenesis of periodontal diseases. Growing evidence proves that helper T cells differentiation, activation, and subset determination are under the strong impact of mTOR signaling. mTOR signaling could promote Th1 and Th17 cell differentiation and inhibit Treg commitment through different mTOR complexes, therefore we anticipate a regulation effect of mTOR signaling on periodontal diseases by regulating CD4⁺ T cell subsets. This review aims to integrate the topical researches about the role of different types of Th cells in the pathogenesis of periodontal diseases, as well as the regulation of mTOR signaling in the specification and selection of Th cell commitment.

What Are the Potential Benefits of Using Bacteriophages in Periodontal Therapy?

Periodontitis, which may result in tooth loss, constitutes both a serious medical and social problem. This pathology, if not treated, can contribute to the development of, among others, pancreatic cancer, cardiovascular diseases or Alzheimer’s disease. The available treatment methods are expensive but not always fully effective. For this reason, the search for and isolation of bacteriophages specific to bacterial strains causing periodontitis seems to be a great opportunity to target persistent colonization by bacterial pathogens and lower the use of antibiotics consequently limiting further development of antibiotic resistance. Furthermore, antimicrobial resistance (AMR) constitutes a growing challenge in periodontal therapy as resistant pathogens may be isolated from more than 70% of patients with periodontitis. The aim of this review is to present the perspective of phage application in the prevention and/or treatment of periodontitis alongside its complicated multifactorial aetiology and emphasize the challenges connecting composition and application of effective phage preparation.

A Phenolic-rich Extract of Cocoa (Theobroma cacao L.) Beans Impairs the Pathogenic Properties of Porphyromonas gingivalis and Attenuates the Activation of Nuclear Factor Kappa B in a Monocyte Model

Periodontitis, an inflammatory disease that affects tooth-supporting tissues, is the result of a polymicrobial infection involving mainly Gram negative anaerobic bacteria. The aim of the present study was to investigate the effects of a phenolic-rich extract of cocoa (Theobroma cacao L.) beans on the pathogenic properties of Porphyromonas gingivalis, which is well-known as a keystone pathogen in the development of periodontitis. The effect of the cocoa extract on P. gingivalis-induced activation of the nuclear factor kappa B (NF-κB) transcription factor in a monocyte model was also assessed. The cocoa extract, whose major phenolic compound was epicatechin, inhibited the growth, hemolytic activity, proteolytic activities, and adherence properties (basement membrane matrix, erythrocytes) of P. gingivalis in a dose-dependent manner. It also protected the barrier function of a keratinocyte model against the deleterious effects mediated by P. gingivalis, and attenuated reactive oxygen species (ROS) production by oral keratinocytes treated with P. gingivalis. Lastly, the cocoa extract showed an anti-inflammatory property by preventing P. gingivalis-induced NF-κB activation in monocytes. In conclusion, this in vitro study highlighted the potential value of an epicatechin-rich extract of cocoa beans for preventing and/or treating periodontal diseases.

Links between Insulin Resistance and Periodontal Bacteria: Insights on Molecular Players and Therapeutic Potential of Polyphenols

Type 2 diabetes is a metabolic disease mainly associated with insulin resistance during obesity and constitutes a major public health problem worldwide. A strong link has been established between type 2 diabetes and periodontitis, an infectious dental disease characterized by chronic inflammation and destruction of the tooth-supporting tissue or periodontium. However, the molecular mechanisms linking periodontal bacteria and insulin resistance remain poorly elucidated. This study aims to summarize the mechanisms possibly involved based on in vivo and in vitro studies and targets them for innovative therapies. Indeed, during periodontitis, inflammatory lesions of the periodontal tissue may allow periodontal bacteria to disseminate into the bloodstream and reach tissues, including adipose tissue and skeletal muscles that store glucose in response to insulin. Locally, periodontal bacteria and their components, such as lipopolysaccharides and gingipains, may deregulate inflammatory pathways, altering the production of pro-inflammatory cytokines/chemokines. Moreover, periodontal bacteria may promote ROS overproduction via downregulation of the enzymatic antioxidant defense system, leading to oxidative stress. Crosstalk between players of inflammation and oxidative stress contributes to disruption of the insulin signaling pathway and promotes insulin resistance. In parallel, periodontal bacteria alter glucose and lipid metabolism in the liver and deregulate insulin production by pancreatic β-cells, contributing to hyperglycemia. Interestingly, therapeutic management of periodontitis reduces systemic inflammation markers and ameliorates insulin sensitivity in type 2 diabetic patients. Of note, plant polyphenols exert anti-inflammatory and antioxidant activities as well as insulin-sensitizing and anti-bacterial actions. Thus, polyphenol-based therapies are of high interest for helping to counteract the deleterious effects of periodontal bacteria and improve insulin resistance.

Eriodictyol Suppresses Porphyromonas gingivalis-Induced Reactive Oxygen Species Production by Gingival Keratinocytes and the Inflammatory Response of Macrophages

Porphyromonas gingivalis is a key pathogen of periodontitis, an inflammatory disease that affects the tooth-supporting tissues. The aim of the present study was to investigate the effects of the flavanone eriodictyol on P. gingivalis-induced reactive oxygen species (ROS) production by gingival keratinocytes and the inflammatory response of macrophages. Porphyromonas gingivalis and H2O2 acted synergistically to induce ROS production by keratinocytes. The presence of eriodictyol significantly attenuated ROS production in a dose-dependent manner. We used a macrophage model to show that eriodictyol decreases the secretion of IL-1β, IL-6, IL-8, and TNF-α induced by P. gingivalis. Evidence has been brought that this anti-inflammatory property of eriodictyol may be related to its ability to prevent the activation of the NF-κB signaling pathway by P. gingivalis. This periodontal pathogen was also found to be a potent inducer of matrix metalloproteinase (MMP) production by macrophages, including MMP-2, MMP-8, and MMP-9. Eriodictyol dose-dependently inhibited the production of all three MMPs. Lastly, eriodictyol inhibited the catalytic activity of both MMP-9 and P. gingivalis collagenase. In conclusion, eriodictyol may be a potential therapeutic agent for preventing and/or treating periodontal disease due to its antioxidant, anti-inflammatory, and anti-proteinase properties.

Antibodies to Porphyromonas gingivalis Are Increased in Patients with Severe Periodontitis, and Associate with Presence of Specific Autoantibodies and Myocardial Infarction

There is accumulating data suggesting that periodontitis is associated with increased risk of systemic and autoimmune diseases, including cardiovascular disease, rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), and there is an unmet need to identify these individuals early. With the periodontal bacteria Porphyromonas gingivalis (Pg) as one of the key drivers of periodontitis, we set out to investigate whether antibodies to Pg virulence factor arginine gingipain (Rgp) could serve as a biomarker for periodontitis patients at increased risk of autoimmunity and systemic disease. We measured serum anti-Rgp IgG in three study populations: PAROKRANK (779 individuals with myocardial infarction (MI); 719 controls), where 557 had periodontitis, and 312 were positive for autoantibodies associated with RA/SLE; the PerioGene North pilot (41 periodontitis; 39 controls); and an SLE case/control study (101 SLE; 100 controls). Anti-Rgp IgG levels were increased in severe periodontitis compared to controls (p < 0.0001), in individuals positive for anti-citrullinated protein antibodies (p = 0.04) and anti-dsDNA antibodies (p = 0.035), compared to autoantibody-negative individuals; and in MI patients versus matched controls (p = 0.035). Our data support longitudinal studies addressing the role of anti-Rgp antibodies as biomarkers for periodontitis patients at increased risk of developing autoimmunity linked to RA and SLE, and mechanisms underpinning these associations.

Quantification of Helicobacter pylori and its oncoproteins in oral cavity. A cross sectional study

OBJECTIVE

To identify Helicobacter pylori (H.pylori) and related oncogenic and virulent proteins (CagA and VacA) in patients with gingivitis, periodontitis, oral cancer and gastric cancer.

METHODS

Subgingival plaque samples were collected from 90 individuals with either gingivitis/ periodontitis (group A, n=30), oral cancer (group B, n=30) and gastric cancer (group C, n=30). H.pylori was identified by real time- polymerase chain reaction (RT-PCR). The virulent organisms were detected by identification of proteins CagA and VacA through Enzyme Linked Immuno Sorbent Assay (ELISA).

RESULTS

We identified the presence of H.pylori in subgingival plaque samples among a large majority (76/90) of our study cohort. The proportions of CagA and VacA identified among H.pylori individuals with periodontal inflammation and oral cancer were lower than those diagnosed with gastric cancer. Furthermore, the relative risk of oral cancer based on the presence of the organism was no different to those with gingivitis/periodontitis.

CONCLUSION

The findings of our study does not indicate significant association between the organism and oral cancer but preludes that the oral cavity could act as a potential niche for H.pylori. The possibility for CagA and VacA proteins to be pathogenic in oral cavity is highly possible and to be researched extensively.

Effects of Saliva From Periodontally Healthy and Diseased Subjects on Barrier Function and the Inflammatory Response in in vitro Models of the Oral Epithelium

Background: Periodontitis is a multifactorial, bacteria-mediated chronic inflammatory disease that results in the progressive destruction of the tooth-supporting tissues. It is well-known that saliva from subjects suffering from this disease generally contains higher levels of pro-inflammatory mediators, matrix metalloproteinases (MMP), and bacteria-derived toxic products. The aim of this study was to investigate and compare the effects of saliva from periodontally healthy and diseased subjects on the barrier function and inflammatory response in in vitro models of the oral epithelium.

Methods: Unstimulated saliva samples from two groups of subjects, one with a healthy periodontium (n = 12) and one with severe generalized periodontitis (n = 11), were filter-sterilized. All the saliva samples were analyzed using an immunological multiplex assay to determine the levels of various cytokines and MMPs relevant to periodontitis. The impact of saliva on epithelial barrier integrity was assessed by monitoring transepithelial electrical resistance (TER) in an oral epithelium model using the B11 keratinocyte cell line. GMSM-K oral epithelial cells were treated with saliva from both groups to determine their ability to induce the secretion of interleukin-6 (IL-6) and interleukin-8 (IL-8), as determined by an enzyme-linked immunosorbent assay (ELISA).

Results: Saliva from the periodontitis subjects contained significantly higher concentrations of matrix metalloproteinase-8 (MMP-8), matrix metalloproteinase-9 (MMP-9), IL-8, and C-X-C motif chemokine ligand 1 (CXCL1) compared to saliva from the healthy subjects. Saliva from the healthy and periodontitis subjects affected cytokine secretion and TER in a similar manner. More specifically, saliva from both groups increased TER and induced IL-6 and IL-8 secretion in the in vitro oral epithelium models used.

Conclusion: Independently of the presence or absence of periodontitis, saliva can increase the relative TER and the secretion of IL-6 and IL-8 in in vitro models of the oral epithelium.

Antimicrobial peptides, conventional antibiotics, and their synergistic utility for the treatment of drug-resistant infections

Antimicrobial peptides (AMPs), also known as host defense peptides (HDPs), are important effector immune defense molecules in multicellular organisms. AMPs exert their antimicrobial activities through several mechanisms; thus far, induction of drug resistance through AMPs has been regarded as unlikely. Therefore, they have great potential as new generation antimicrobial agents. To date, more than 30 AMP-related drugs are in the clinical trial phase. In recent years, studies show that some AMPs and conventional antibiotics have synergistic effects. The combined use of AMPs and antibiotics can kill drug-resistant pathogens, prevent drug resistance, and significantly improve the therapeutic effects of antibiotics. In this review, we discuss the progress in synergistic studies on AMPs and conventional antibiotics. An overview of the current understanding of the functional scope of AMPs, ongoing clinical trials, and challenges in the development processes are also presented.

Oral and Gut Microbial Dysbiosis and Non-alcoholic Fatty Liver Disease: The Central Role of Porphyromonas gingivalis

Gut microbiota play many important roles, such as the regulation of immunity and barrier function in the intestine, and are crucial for maintaining homeostasis in living organisms. The disruption in microbiota is called dysbiosis, which has been associated with various chronic inflammatory conditions, food allergies, colorectal cancer, etc. The gut microbiota is also affected by several other factors such as diet, antibiotics and other medications, or bacterial and viral infections. Moreover, there are some reports on the oral-gut-liver axis indicating that the disruption of oral microbiota affects the intestinal biota. Non-alcoholic fatty liver disease (NAFLD) is one of the systemic diseases caused due to the dysregulation of the oral-gut-liver axis. NAFLD is the most common liver disease reported in the developed countries. It includes liver damage ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), cirrhosis, and cancer. Recently, accumulating evidence supports an association between NAFLD and dysbiosis of oral and gut microbiota. Periodontopathic bacteria, especially Porphyromonas gingivalis, have been correlated with the pathogenesis and development of NAFLD based on the clinical and basic research, and immunology. P. gingivalis was detected in the liver, and lipopolysaccharide from this bacteria has been shown to be involved in the progression of NAFLD, thereby indicating a direct role of P. gingivalis in NAFLD. Moreover, P. gingivalis induces dysbiosis of gut microbiota, which promotes the progression of NAFLD, through disrupting both metabolic and immunologic pathways. Here, we review the roles of microbial dysbiosis in NAFLD. Focusing on P. gingivalis, we evaluate and summarize the most recent advances in our understanding of the relationship between oral-gut microbiome symbiosis and the pathogenesis and progression of non-alcoholic fatty liver disease, as well as discuss novel strategies targeting both P. gingivalis and microbial dysbiosis.

Pyroptosis-Mediated Periodontal Disease

Pyroptosis is a caspase-dependent process relevant to the understanding of beneficial host responses and medical conditions for which inflammation is central to the pathophysiology of the disease. Pyroptosis has been recently suggested as one of the pathways of exacerbated inflammation of periodontal tissues. Hence, this focused review aims to discuss pyroptosis as a pathological mechanism in the cause of periodontitis. The included articles presented similarities regarding methods, type of cells applied, and cell stimulation, as the outcomes also point to the same direction considering the cellular events. The collected data indicate that virulence factors present in the diseased periodontal tissues initiate the inflammasome route of tissue destruction with caspase activation, cleavage of gasdermin D, and secretion of interleukins IL-1β and IL-18. Consequently, removing periopathogens’ virulence factors that trigger pyroptosis is a potential strategy to combat periodontal disease and regain tissue homeostasis.

Periodontal Inflammation and Systemic Diseases: An Overview

Periodontitis is a common inflammatory disease of infectious origins that often evolves into a chronic condition. Aside from its importance as a stomatologic ailment, chronic periodontitis has gained relevance since it has been shown that it can develop into a systemic condition characterized by unresolved hyper-inflammation, disruption of the innate and adaptive immune system, dysbiosis of the oral, gut and other location's microbiota and other system-wide alterations that may cause, coexist or aggravate other health issues associated to elevated morbi-mortality. The relationships between the infectious, immune, inflammatory, and systemic features of periodontitis and its many related diseases are far from being fully understood and are indeed still debated. However, to date, a large body of evidence on the different biological, clinical, and policy-enabling sources of information, is available. The aim of the present work is to summarize many of these sources of information and contextualize them under a systemic inflammation framework that may set the basis to an integral vision, useful for basic, clinical, and therapeutic goals.

Western and non-western gut microbiomes reveal new roles of Prevotella in carbohydrate metabolism and mouth-gut axis

The abundance and diversity of host-associated Prevotella species have a profound impact on human health. To investigate the composition, diversity, and functional roles of Prevotella in the human gut, a population-wide analysis was carried out on 586 healthy samples from western and non-western populations including the largest Indian cohort comprising of 200 samples, and 189 Inflammatory Bowel Disease samples from western populations. A higher abundance and diversity of Prevotella copri species enriched in complex plant polysaccharides metabolizing enzymes, particularly pullulanase containing polysaccharide-utilization-loci (PUL), were found in Indian and non-western populations. A higher diversity of oral inflammations-associated Prevotella species and an enrichment of virulence factors and antibiotic resistance genes in the gut microbiome of western populations speculates an existence of a mouth-gut axis. The study revealed the landscape of Prevotella composition in the human gut microbiome and its impact on health in western and non-western populations.

The secretion of cytokines by peripheral blood mononuclear cells of patients with periodontitis and healthy controls when exposed to H2S

Background: Hydrogen sulfide(H₂S) is a bacterial metabolite produced as a result of bacterial growth in subgingival pockets, suggested to partake in the pathogenesis of periodontitis. H₂S has previously been shown to induce the secretion of the pro-inflammatory cytokines IL-1β and IL-18 via the NLRP3 inflammasome in monocytes.

Objective: To investigate the non-NLRP3 inflammasome-dependent immunological response of human peripheral blood mononuclear cells (PBMCs) of periodontitis patients and healthy controls exposed to H₂S in vitro.

Methods: PBMCs of periodontitis patients(N = 31) and healthy controls(N = 32) were exposed to 1 mM sodium hydrosulfide (NaHS) at 37°C for 24 h and the secretion of cytokines was compared to resting cells. TNF-α, IFN-γ, IL-6, IL-8, IL-12p40, IL-12p70, IL-17, MCP-1, and IL-1Ra secretions were measured with Bio-Plex Pro™ Human Cytokine Assay.

Results: H₂S triggered the secretion of the pro-inflammatory IFN-γ, IL-6, IL-17, TNF-α, IL-12p40, and IL-12p70, while the reverse was seen for IL-1Ra. In addition, a higher basal secretion of IFN-γ, IL-6, IL-12p70, IL-17 and MCP-1 was seen from PBMCs of periodontitis patients compared to healthy controls.

Conclusion: The bacterial metabolite H₂S triggers the secretion of pro-inflammatory cytokines from PBMCs and may thus have a prominent role in the host-bacteria interplay in periodontitis.

Pathological and Therapeutic Approach to Endotoxin-Secreting Bacteria Involved in Periodontal Disease

It is widely recognized that periodontal disease is an inflammatory entity of infectious origin, in which the immune activation of the host leads to the destruction of the supporting tissues of the tooth. Periodontal pathogenic bacteria like Porphyromonas gingivalis, that belongs to the complex net of oral microflora, exhibits a toxicogenic potential by releasing endotoxins, which are the lipopolysaccharide component (LPS) available in the outer cell wall of Gram-negative bacteria. Endotoxins are released into the tissues causing damage after the cell is lysed. There are three well-defined regions in the LPS: one of them, the lipid A, has a lipidic nature, and the other two, the Core and the O-antigen, have a glycosidic nature, all of them with independent and synergistic functions. Lipid A is the "bioactive center" of LPS, responsible for its toxicity, and shows great variability along bacteria. In general, endotoxins have specific receptors at the cells, causing a wide immunoinflammatory response by inducing the release of pro-inflammatory cytokines and the production of matrix metalloproteinases. This response is not coordinated, favoring the dissemination of LPS through blood vessels, as well as binding mainly to Toll-like receptor 4 (TLR4) expressed in the host cells, leading to the destruction of the tissues and the detrimental effect in some systemic pathologies. Lipid A can also act as a TLRs antagonist eliciting immune deregulation. Although bacterial endotoxins have been extensively studied clinically and in a laboratory, their effects on the oral cavity and particularly on periodontium deserve special attention since they affect the connective tissue that supports the tooth, and can be linked to advanced medical conditions. This review addresses the distribution of endotoxins associated with periodontal pathogenic bacteria and its relationship with systemic diseases, as well as the effect of some therapeutic alternatives.

Comparison of the modulatory effects of three structurally similar potential prebiotic substrates on an in vitro multi-species oral biofilm

Previous research identified potential prebiotic substrates for oral health like the structural analogues N-acetyl-D-mannosamine (NADM) and N-acetyl-D-glucosamine (NADG). The main hypothesis of the current study was twofold. Firstly, it was hypothesized that the modulatory effects of NADM are not limited to changes in multi-species oral biofilm composition, but also include effects on metabolism, virulence, and inflammatory potential. Secondly, the presence and orientation of their N-acetyl group could play a role. Therefore, a comparison was made between the effects of NADM, NADG and D-(+)-mannose on multi-species oral biofilms. Besides a beneficial compositional shift, NADM-treated biofilms also showed an altered metabolism, a reduced virulence and a decreased inflammatory potential. At a substrate concentration of 1 M, these effects were pronounced for all biofilm aspects, whereas at ~ 0.05 M (1%_(w/v)) only the effects on virulence were pronounced. When comparing between substrates, both the presence and orientation of the N-acetyl group played a role. However, this was generally only at 1 M and dependent on the biofilm aspect. Overall, NADM was found to have different effects at two concentrations that beneficially modulate in vitro multi-species oral biofilm composition, metabolism, virulence and inflammatory potential. The presence and orientation of the N-acetyl group influenced these effects.

Antibacterial Activity of Boswellia sacra Flueck. Oleoresin Extract against Porphyromonas gingivalis Periodontal Pathogen

Boswellia sacra Flueck. oleoresin extract (frankincense) has traditionally been used in the treatment of different diseases, but there are no sufficient studies on its potential activity against periodontal pathogens. Therefore, antibacterial and antibiofilm activity of frankincense extract against Porphyromonas gingivalis clinical isolates were studied. The phytochemical composition of the volatile components of the extract was identified by GC-MS analysis revealing 49 compounds as trans-nerolidyl formate, cycloartenol acetate, ursenoic acid 3-oxomethyl ester, bisabolene epoxide, and kaur-16-ene. It decreased the growth and increased the leakage of nucleotides in 58.3% and 33.3% of isolates, respectively. Additionally, it reduced the extracellular polysaccharide production and the cell surface hydrophobicity in 41.67% and 50% of the isolates, respectively. Crystal violet assay revealed inhibition of biofilm formation by the tested isolates. Light microscope and scanning electron microscope were used to examine the biofilms and they confirmed the reduction of biofilm formation by frankincense extract. Downregulation of the genes linked to biofilm formation (fimA, hagA, and hagB) was observed using qRT-PCR after treatment with the frankincense extract. This study suggested that the frankincense extract could exhibit antibacterial and antibiofilm activity against P. gingivalis isolates. Thus, the frankincense extract could be used as a treatment approach for periodontitis.

Inflammasomes in Alveolar Bone Loss

Bone remodeling is tightly controlled by osteoclast-mediated bone resorption and osteoblast-mediated bone formation. Fine tuning of the osteoclast-osteoblast balance results in strict synchronization of bone resorption and formation, which maintains structural integrity and bone tissue homeostasis; in contrast, dysregulated bone remodeling may cause pathological osteolysis, in which inflammation plays a vital role in promoting bone destruction. The alveolar bone presents high turnover rate, complex associations with the tooth and periodontium, and susceptibility to oral pathogenic insults and mechanical stress, which enhance its complexity in host defense and bone remodeling. Alveolar bone loss is also involved in systemic bone destruction and is affected by medication or systemic pathological factors. Therefore, it is essential to investigate the osteoimmunological mechanisms involved in the dysregulation of alveolar bone remodeling. The inflammasome is a supramolecular protein complex assembled in response to pattern recognition receptors and damage-associated molecular patterns, leading to the maturation and secretion of pro-inflammatory cytokines and activation of inflammatory responses. Pyroptosis downstream of inflammasome activation also facilitates the clearance of intracellular pathogens and irritants. However, inadequate or excessive activity of the inflammasome may allow for persistent infection and infection spreading or uncontrolled destruction of the alveolar bone, as commonly observed in periodontitis, periapical periodontitis, peri-implantitis, orthodontic tooth movement, medication-related osteonecrosis of the jaw, nonsterile or sterile osteomyelitis of the jaw, and osteoporosis. In this review, we present a framework for understanding the role and mechanism of canonical and noncanonical inflammasomes in the pathogenesis and development of etiologically diverse diseases associated with alveolar bone loss. Inappropriate inflammasome activation may drive alveolar osteolysis by regulating cellular players, including osteoclasts, osteoblasts, osteocytes, periodontal ligament cells, macrophages, monocytes, neutrophils, and adaptive immune cells, such as T helper 17 cells, causing increased osteoclast activity, decreased osteoblast activity, and enhanced periodontium inflammation by creating a pro-inflammatory milieu in a context- and cell type-dependent manner. We also discuss promising therapeutic strategies targeting inappropriate inflammasome activity in the treatment of alveolar bone loss. Novel strategies for inhibiting inflammasome signaling may facilitate the development of versatile drugs that carefully balance the beneficial contributions of inflammasomes to host defense.