Localization and density of Porphyromonas gingivalis and Tannerella forsythia in gingival and subgingival granulation tissues affected by chronic or aggressive periodontitis

Periodontal granulation tissue - To remove or not to remove, that is the question

Formation of granulation tissue is a fundamental phase in periodontal wound healing with subsequent maturation leading to regeneration or repair. However, persistently inflamed granulation tissue presents in osseous defects as a result of periodontitis and is routinely disrupted and discarded with non-surgical and surgical therapy to facilitate wound healing or improve chances of regeneration. Histological assessment suggests that granulation tissue from periodontitis-affected sites is effectively a chronic inflammatory tissue resulting from impaired wound healing due to persistence of bacterial dysbiotic bioflim. Nevertheless, the immunomodulatory potential and stem cell characteristics in granulation tissue have also raised speculation about the tissue's regenerative potential. This has led to the conception and recent implementation of surgical techniques which preserve granulation tissue with the intention of enhancing innate regenerative potential and improve clinical outcomes. As knowledge of fundamental cellular and molecular functions regulating periodontitis-affected granulation tissue is still scarce, this review aimed to provide a summary of current understanding of granulation tissue in the context of periodontal wound healing. This may provide new insights into clinical practice related to the management of granulation tissue and stimulate further investigation.

The Bacteroidetes Q-rule and glutaminyl cyclase activity increase the stability of extracytoplasmic proteins

IMPORTANCE

Exclusively in the Bacteroidetes phylum, most proteins exported across the inner membrane via the Sec system and released into the periplasm by type I signal peptidase have N-terminal glutamine converted to pyroglutamate. The reaction is catalyzed by the periplasmic enzyme glutaminyl cyclase (QC), which is essential for the growth of Porphyromonas gingivalis and other periodontopathogens. Apparently, pyroglutamyl formation stabilizes extracytoplasmic proteins and/or protects them from proteolytic degradation in the periplasm. Given the role of P. gingivalis as the keystone pathogen in periodontitis, P. gingivalis QC is a promising target for the development of drugs to treat and/or prevent this highly prevalent chronic inflammatory disease leading to tooth loss and associated with severe systemic diseases.

Biological Activities of Bismuth Compounds: An Overview of the New Findings and the Old Challenges Not Yet Overcome

Bismuth-based drugs have been used primarily to treat ulcers caused by Helicobacter pylori and other gastrointestinal ailments. Combined with antibiotics, these drugs also possess synergistic activity, making them ideal for multiple therapy regimens and overcoming bacterial resistance. Compounds based on bismuth have a low cost, are safe for human use, and some of them are also effective against tumoral cells, leishmaniasis, fungi, and viruses. However, these compounds have limited bioavailability in physiological environments. As a result, there is a growing interest in developing new bismuth compounds and approaches to overcome this challenge. Considering the beneficial properties of bismuth and the importance of discovering new drugs, this review focused on the last decade's updates involving bismuth compounds, especially those with potent activity and low toxicity, desirable characteristics for developing new drugs. In addition, bismuth-based compounds with dual activity were also highlighted, as well as their modes of action and structure-activity relationship, among other relevant discoveries. In this way, we hope this review provides a fertile ground for rationalizing new bismuth-based drugs.

The Contribution of the Human Oral Microbiome to Oral Disease: A Review

The oral microbiome is an emerging field that has been a topic of discussion since the development of next generation sequencing and the implementation of the human microbiome project. This article reviews the current literature surrounding the oral microbiome, briefly highlighting most recent methods of microbiome characterization including cutting edge omics, databases for the microbiome, and areas with current gaps in knowledge. This article also describes reports on microorganisms contained in the oral microbiome which include viruses, archaea, fungi, and bacteria, and provides an in-depth analysis of their significant roles in tissue homeostasis. Finally, we detail key bacteria involved in oral disease, including oral cancer, and the current research surrounding their role in stimulation of inflammatory cytokines, the role of gingival crevicular fluid in periodontal disease, the creation of a network of interactions between microorganisms, the influence of the planktonic microbiome and cospecies biofilms, and the implications of antibiotic resistance. This paper provides a comprehensive literature analysis while also identifying gaps in knowledge to enable future studies to be conducted.

Prevalence of Periodontal Pathogens in Slovak Patients with Periodontitis and Their Possible Aspect of Transmission from Companion Animals to Humans

Oral health and diseases are greatly influenced by oral bacteria. During dysbiosis, bacterial composition changes, which can lead to periodontitis. Periodontitis in humans is associated with periodontal pathogens such as Treponema denticola, Porphyromonas gingivalis, Tannerella forsythia and Aggregatibacter actinomycetemcomitans. Animal-to-human transmission of some of these pathogens has also been reported. The aim of this study was to evaluate the prevalence of periodontal pathogens in Slovak patients and to assess the possible risk of transmission of these pathogens from animals to their owners. The presence of periodontal pathogens in dental plaque was monitored by PCR. Amplified products were analysed using Sanger sequencing. T. forsythia isolates were assessed for the susceptibility to different antibiotics using the disk diffusion method. In humans, T. denticola, P. gingivalis, T. forsythia and A. actinomycetemcomitans were present in 69.23%, 69.23%, 100% and 84.62%, respectively. Most isolates of T. forsythia were susceptible to amoxicillin-clavulanic acid, clindamycin and moxifloxacin, but they were resistant to metronidazole. The transmission of T. forsythia from animals to their owners was not proven based on sequence analysing. On the other hand, transmission of Porphyromonas gulae was confirmed, but the risk of its involvement in the pathogenesis of periodontitis in humans must be further investigated.

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.

Topical application of Porphyromonas gingivalis into the gingival pocket in mice leads to chronic‑active infection, periodontitis and systemic inflammation

Porphyromonas gingivalis (Pg), one of the 'red-complex' perio-pathogens known to play a critical role in the development of periodontitis, has been used in various animal models to mimic human bacteria-induced periodontitis. In order to achieve a more realistic animal model of human Pg infection, the present study investigated whether repeated small-volume topical applications of Pg directly into the gingival pocket can induce local infection, including periodontitis and systemic vascular inflammation in wild-type mice. Freshly cultured Pg was topically applied directly into the gingival pocket of the second molars for 5 weeks (3 times/week). After the final application, the mice were left in cages for 4 or 8 weeks and sacrificed. The status of Pg colony formation in the pocket, gingival inflammation, alveolar bone loss, the expression levels of pro-inflammatory cytokines in the serum and aorta, the presence of anti-Pg lipopolysaccharide (LPS) and gingipain (Kpg and RgpB) antibodies in the serum, as well as the accumulation of Pg LPS and gingipain aggregates in the gingiva and arterial wall were evaluated. The topical application of Pg into the gingival pocket induced the following local and systemic pathohistological changes in mice when examined at 4 or 8 weeks after the final topical Pg application: Pg colonization in the majority of gingival pockets; increased gingival pocket depths; gingival inflammation indicated by the increased expression of TNF-α, IL-6 and IL-1β; significant loss of alveolar bone at the sites of topical Pg application; and increased levels of pro-inflammatory cytokines, such as TNF-α, IL-1β, IL-17, IL-13, KC and IFN-γ in the serum in comparison to those from mice receiving PBS. In addition, the Pg application/colonization model induced anti-Pg LPS and gingipain antibodies in serum, as well as the accumulation of Pg LPS and gingipain aggregates in the gingivae and arterial walls. To the best of our knowledge, this mouse model represents the first example of creating a more sustained local infection in the gingival tissues of wild-type mice and may prove to be useful for the investigation of the more natural and complete pathogenesis of the bacteria in the development of local oral and systemic diseases, such as atherosclerosis. It may also be useful for the determination of a treatment/prevention/efficacy model associated with Pg-induced colonization periodontitis in mice.

Possible association between COVID-19 caused stress and periodontal health - a pilot study

Introduction/Objective. Stress is proposed as one of the risk factors linked to periodontal disease. The COVID-19 pandemic has a significant negative impact in population on mental and somatic health. This study aimed to examine the possible association between COVID-19 resultant stress and periodontal health. Methods. An observational pilot study was conducted from March 2020 to October 2021 and included 202 participants. Participants graded their stress level using the Perceived Stress Scale (PSS). Periodontal Disease Index and Clinical Attachment Level were determined. Participants were categorized into following groups: Ia (low stress), IIa (moderate stress), IIIa (high stress) and Ib (healthy parodontium), IIb (mild periodontal disease), IIIb (severe periodontal disease). The cause/effect relationship between stress and health was measured. Results. The results indicated a statistically significant difference between the groups classified according to the stress level concerning values of all the measured parameters. The Poisson regression analysis showed that in both models, crude and adjusted, periodontal health-related covariables were higher in subjects perceiving greater stress (Periodontal Disease Index ? Pradjusted = 1.042, 95% CI [1.030?1.055] and Clinical Attachment Level ? PRadjusted = 1.108, 95% CI [1.094?1.122]). Conslusion. During COVID-19 pandemic increased stress has a negative impact on mental health and may result in the deterioration of the entire oral cavity?s health, including the periodontium.

The Th17/Treg cell balance: crosstalk among the immune system, bone and microbes in periodontitis

Periodontopathic bacteria constantly stimulate the host, which causes an immune response, leading to host-induced periodontal tissue damage. The complex interaction and imbalance between Th17 and Treg cells may be critical in the pathogenesis of periodontitis. Furthermore, the RANKL/RANK/OPG system plays a significant role in periodontitis bone metabolism, and its relationship with the Th17/Treg cell imbalance may be a bridge between periodontal bone metabolism and the immune system. This article reviews the literature related to the Th17/Treg cell imbalance mediated by pathogenic periodontal microbes, and its mechanism involving RANKL/RANK/OPG in periodontitis bone metabolism, in an effort to provide new ideas for the study of the immunopathological mechanism of periodontitis.

Potential Microbiological Risk Factors Associated With Periodontitis and Periodontal Health Disparities

Periodontitis disproportionately affects different racial and ethnic populations. In this study, we used qPCR to determine and compare oral microbial profiles in dental plaque samples from 191 periodontitis patients of different ethnic/racial backgrounds. We also obtained the periodontal parameters of these patients retrospectively using axiUm and performed statistical analysis using SAS 9.4. We found that in this patient cohort, neighborhood median incomes were significantly higher among Caucasians Americans (CAs) than among African Americans (AAs) and Hispanic Americans (HAs). Levels of total bacteria and Porphyromonas gingivalis, a keystone periodontal pathogen, were not evenly distributed among the three groups. We confirmed our previous findings that Streptococcus cristatus reduces P. gingivalis virulence potential and likely serves as a beneficial bacterium. We also showed the ratio of S. cristatus to P. gingivalis to be significantly higher in CAs than in HAs and AAs. Our results suggest that higher levels of P. gingivalis and lower ratios of S. cristatus to P. gingivalis may contribute to periodontal health disparities.

Pathological and immunological differences of arterial thrombi and wall caused by three different periodontal bacterial injections in rat models and proposals on the pathogeneses of vascular diseases

OBJECTIVES

Periodontal bacteria that have been studied show a strong connection to various vascular diseases. Among the many kinds of periodontal bacteria, Porphyromonas gingivalis (Pg) is well examined in the general aspects and in a rat model. However, whether other periodontal bacteria work or react differently is not studied well.

MATERIAL AND METHODS

We chose Aggregatibacter actinomycetemcomitans (Aa) and Prevotella intermedia (Pi) as different types of periodontal bacteria. Low-density and high-density bacterial solutions were injected in the small artery of rats' groins using our rat model. Eighteen limbs of 9 SD male rats (500-650 g) were used. After 7 days, 14-18 days, and 28 days, the rats were sacrificed. A pathological and an immuno-histochemical study was conducted and reported on the low-density group with 12 limbs because the Pi group lacked a high-density study. Immuno-histochemical staining of live Pg was performed on three limbs of three rats at 1 h, 3 h, and 1 week after injection.

RESULTS

The appearances from the acute, at 7 days, to chronic phases, at 28 days, were observed. The differences of the species were certainly observed in the internal elastic lamina (IEL), and immuno-histochemical reactions. The inflammatory reactions, such as cellular distribution or intra-thrombus materials, were similar in all. One week later, we could not see any living bacteria in the specimen or immunological observation.

CONCLUSIONS

The three species were essentially the same, except for Aa's stronger disruption of IEL, and more CD3 (Pan T cell) in Pi and more CD79a (Pan B cell) in Pg. We propose a new concept of a possible mechanism of vascular diseases, in which the work of LPS (lipopolysaccharides) and a toll-like receptor (TLR) is emphasized.

Research on Autophagy of Gingiva Epithelial Cell Induced by Porphyromonas Gingivalis Regulated by Long Non-Coding RNA Transforming Growth Factor Beta-2 Overlapping Transcript 1 (LncRNA TGFB2-OT1)

Our study analyzes lncRNA TGFB2-OT1’s effect on autophagy and migration of gingiva epithelial cells and porphyromonas gingivalis. The expression of TGFB2-OT1 and TIMP2 in GEC cells was detected by QRT-PCR. Cell proliferation and colon formation was assessed by MTT method and colony forming assay. The relation between TGFB2-OT1 and TIMP2 was confirmed luciferase assay. The autophagy, apoptosis rate and period distribution was detected by flow cytometry along with analysis of porphyromonas gingivalis of GEC cells. TGFB2-OT1 was upregulated significantly as shown by IncRNA array. TGFB2-OT1 overexpression in GEC cells improved cell proliferation and migration, enhanced the sensibility of gingiva epithelial cell on the porphyromonas gingivalis and increased autophagy. The GEC cells were blocked at G2/M period. The TIMP2 was a direct target of TGFB2-OT1. In conclusion, TIMP2 participates in the up-regulation of MMP10 induced by TGFB2-OT1. The lncRNA TGFB2-OT1 maybe be a potential biomarker to assess the autophagy of gingiva epithelial cell.

Is the progression rate of periodontitis related to subgingival biofilm composition or gingival crevicular fluid IL-1β and MMP-8 concentrations?

AIM OF THE STUDY

To analyze the composition of subgingival biofilm and to assess the concentration of IL-1 and MMP-8 in gingival crevicular fluid (GCF) from deep periodontal pockets in patients with severe periodontitis to determine whether the presence of specific microbial species or the severity of the host's immune response can be helpful in assessing the dynamics of disease.

MATERIAL AND METHODS

The study included 30 individuals with periodontitis Grade B and 19 subjects with periodontitis Grade C. Quantitative and qualitative microbiological analysis of flora in pockets ≥ 7 mm was performed for the presence of selected periopathogens of the orange, red complex and Aggregatibacter actinomycetemcomitans using real-time PCR. The concentrations of IL-1 and MMP-8 in GCF were evaluated with the ELISA method.

RESULTS

There were no differences in the composition of the subgingival biofilm depending on the diagnosis. The concentration of MMP-8 in GCF was significantly higher in periodontitis Grade C than in periodontitis Grade B (61 ng/µl and 37 ng/µl respectively, p = 0.039). The concentration of IL-1β was similar in both groups. No significant correlations were observed between the occurrence of individual periopathogens and concentrations of MMP-8 and IL-1β depending on the diagnosis.

CONCLUSIONS

Periodontitis grade may not be distinguished according to microbial analysis of subgingival biofilm or to concentration of IL-1β in GCF. On the other hand, higher concentrations of MMP-9 in GCF from deep pockets may be helpful in detecting subjects particularly prone to occurrence and rapid progress of periodontitis.

IFN-γ or IL-4 polarization impacts the response of gingival fibroblasts to oral bacteria

BACKGROUND AND OBJECTIVE

We previously reported that gingival fibroblasts (GFs) can be polarized into functionally distinct subtypes, immune-activating but tissue-destructive or tissue-reparative, in response to T helper (Th1) and Th2 stimuli, respectively. The purpose of this study was to evaluate the effect of polarization on GFs responses to oral bacteria.

METHODS

Unprimed (GF(-)) and IFN-γ (GF(IFN-γ)) or IL-4 primed (GF(IL-4)) GFs were stimulated with live Fusobacterium nucleatum or Porphyromonas gingivalis. The mRNA expression of IL-1β, IL-4, LPS-recognizing components (Toll-like receptor (TLR) 4, CD14), molecules involved in antigen presentation (human leukocyte antigen (HLA)-ABC, HLA-DP, CD74, CD40), chemokines (C-X-C motif chemokine (CXCL)10, CXCL11, chemokine (C-C motif) ligand 20 (CCL20)), collagen type 1 alpha 1 (COL1A1), and matrix metalloproteinase (MMP)-1, and the protein levels of IL-1β, CD14, CXCL11, CCL20, and COL1A1 accumulated in supernatants were analyzed using real-time PCR and ELISA.

RESULTS

In response to oral bacteria, the GF(IFN-γ) significantly upregulated the expression of LPS-recognizing components, molecules involved in antigen presentation, CXCL10, and CXCL11, whereas the levels of IL-4 and COL1A1 were downregulated, compared with GF(-). The levels of IL-1β, CCL20, and MMP-1 from GF(IFN-γ) were differently regulated between both bacteria; F. nucleatum was synergistically upregulated, but P. gingivalis was downregulated. The GF(IL-4) stimulated with both bacteria upregulated the levels of IL-4, whereas the levels of TLR4 and chemokines were downregulated, compared with GF(-). The regulation of IL-1β, CD14, CXCL11, CCL20, and COL1A1 proteins showed a similar tendency with mRNA regulation.

CONCLUSION

Polarization of GFs with IFN-γ or IL-4 affected the way that GFs responded to oral bacteria through up or downregulation of inflammatory responses and extracellular matrix control.

Porphyromonas gingivalis ligada a enfermedad periodontal y su relación con la artritis reumatoide: identificación de nuevos mecanismos biomoleculares

Objetivo: revisar la literatura científica existente con respecto a la patogenicidad de Porphyromonas gingivalis, ligada a enfermedad periodontal (EP) (disbiosis oral), y su asociación con la activación de mecanismos fisiopatológicos en la artritis reumatoide (AR), a fin de exponer los nuevos mecanismos biomoleculares implicados. Métodos: búsqueda sistemática en la base de datos del Medical Subject Headings (MeSH), PubMed, Science Direct, Nature y Google académico usando las palabras clave: Aggregatibacter actinomycetemcomitans; artritis reumatoide; citrulinación; disbiosis; odontología; periodontitis; Porphyromonas gingivalis y reumatología. De un total de 297 publicaciones, se seleccionaron 52, todas a partir del año 2018; la selección fue hecha a partir de los criterios de inclusión y exclusión establecidos por los autores. Resultados: la infección por Porphyromonas gingivalis, ligada a la EP, está fuertemente implicada en la patogénesis y desarrollo de AR. Su relación se vincula con el proceso de citrulinación y producción de anticuerpos antipéptidos citrulinados. Se han identificado asociaciones entre la virulencia microbiana de dicho agente y la expresión de múltiples genes, relacionados con la activación de la respuesta inmune y el inicio del proceso inflamatorio crónico. Conclusiones: existe una alta asociación entre la patogenia de ambas enfermedades, donde microorganismos ligados a la EP, como Porphyromonas gingivalis, tienen la capacidad de aumentar la citrulinación, galactosilación, fucosilación, así como la excesiva glicosilación de Fragmentos de unión al antígeno (Fab), y por lo tanto, la agresividad de la AR.

Proteome Analysis of Molecular Events in Oral Pathogenesis and Virus: A Review with a Particular Focus on Periodontitis

Some systemic diseases are unquestionably related to periodontal health, as periodontal disease can be an extension or manifestation of the primary disease process. One example is spontaneous gingival bleeding, resulting from anticoagulant treatment for cardiac diseases. One important aspect of periodontal therapy is the care of patients with poorly controlled disease who require surgery, such as patients with uncontrolled diabetes. We reviewed research on biomarkers and molecular events for various diseases, as well as candidate markers of periodontal disease. Content of this review: (1) Introduction, (2) Periodontal disease, (3) Bacterial and viral pathogens associated with periodontal disease, (4) Stem cells in periodontal tissue, (5) Clinical applications of mass spectrometry using MALDI-TOF-MS and LC-MS/MS-based proteomic analyses, (6) Proteome analysis of molecular events in oral pathogenesis of virus in GCF, saliva, and other oral Components in periodontal disease, (7) Outlook for the future and (8) Conclusions. This review discusses proteome analysis of molecular events in the pathogenesis of oral diseases and viruses, and has a particular focus on periodontitis.

Bismuth drugs tackle Porphyromonas gingivalis and attune cytokine response in human cells

Periodontitis is the leading cause of severe tooth loss and edentulism in adults worldwide and is closely linked to systemic conditions such as diabetes and cardiovascular disease. Porphyromonas gingivalis is the key pathogen in periodontitis. Herein, we provided the first evidence that bismuth drugs suppress P. gingivalis in its planktonic, biofilm, and intracellular states. In total, 42 bismuth-associated proteins were identified including its major virulent factors (e.g., gingipains, hemagglutinin HagA, and fimbriae). Bismuth perturbed its iron acquisition, disturbed the energy metabolism and virulence, and deactivated multiple key enzymes (e.g., superoxide dismutase and thioredoxins). Moreover, bismuth inhibited its biofilm formation and disrupted the 3-day matured biofilms. Notably, the internalized P. gingivalis in various human cells (e.g., human gingival epithelium progenitors, HGEPs) was oppressed by bismuth but not the commonly used antibiotic metronidazole. Importantly, bismuth drugs enabled the counteraction of immuno-inflammatory responses in different host cells perturbed by P. gingivalis. The production of IL-6 and IL-8 attenuated by P. gingivalis in both of native and IL-1β-stimulated HGEPs was restored, while the bacterium-enhanced expression of IL-6, IL-1β, and TNFα in THP-1 macrophages was alleviated. This proof-of-concept study brings prospects for the potential reposition of the routinely used anti-Helicobacter pylori bismuth drugs to better manage inflammatory diseases such as periodontitis and P. gingivalis-related complex systemic disorders.

In Situ Intraepithelial Localizations of Opportunistic Pathogens, Porphyromonas gingivalis and Filifactor alocis, in Human Gingiva

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The gingival epithelium serves as a growth reservoir for opportunistic bacteria.

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Intraepithelial P. gingivalis and F. alocis colonies are detected together in dysbiotic mucosa.

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Increased metabolically active dual species can lead to higher microvasculature.

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Invasion of intraepithelial microvessels leads to systemic pathogen dissemination.

Porphyromonas gingivalis and Filifactor alocis are fastidious oral pathogens and etiological agents associated with chronic periodontitis. Although previous studies showed increased levels of the two obligate anaerobic species in periodontitis patients, methodologies for this knowledge were primarily limited to sampling subgingival plaque, saliva, or gingival crevicular fluid. To evaluate the extent to which P. gingivalis and F. alocis may invade the periodontal tissues, an in situ cross-sectional study was comparatively conducted on the gingival biopsy specimens of patients diagnosed with periodontal health or chronic periodontitis. Immunostained tissue sections for each organism were imaged by Super-Resolution Confocal Scanning Microscopy to determine the relative presence and localization of target bacterial species. Fluorescence-in-situ-hybridization (FISH) coupled with species specific 16S rRNA method was utilized to confirm whether detected bacteria were live within the tissue. In periodontitis, P. gingivalis and F. alocis revealed similarly concentrated localization near the basement membrane or external basal lamina of the gingival epithelium. The presence of both bacteria was significantly increased in periodontitis vs. healthy tissue. However, P. gingivalis was still detected to an extent in health tissue, while only minimal levels of F. alocis were spotted in health. Additionally, the micrographic analyses displayed heightened formation of epithelial microvasculature containing significantly co-localized and metabolically active dual species within periodontitis tissue. Thus, this study demonstrates, for the first-time, spatial arrangements of P. gingivalis and F. alocis in both single and co-localized forms within the complex fabric of human gingiva during health and disease. It also exhibits critical visualizations of co-invaded microvascularized epithelial layer of the tissue by metabolically active P. gingivalis and F. alocis from patients with severe periodontitis. These findings collectively uncover novel visual evidence of a potential starting point for systemic spread of opportunistic bacteria during their chronic colonization in gingival epithelium.

Microbial and Host Factors That Affect Bacterial Invasion of the Gingiva

Periodontitis is a chronic inflammation of the periodontium caused by the loss of homeostasis between subgingival biofilms and susceptible hosts. Bacterial invasion into the gingival tissue and persistent infection are major events that lead to chronic inflammation. The intratissue bacterial communities are as complex as the subgingival biofilms and can also form biofilm-like structures, which will serve as a reservoir for local and systemic infections. The epithelium forms physical, chemical, and immunological barriers against invading microbes. Nevertheless, many bacterial species can invade the gingival epithelium through transcellular and paracellular pathways. In addition, both genetic and environmental factors of the hosts can affect epithelial barrier functions and thus bacterial invasion of the gingiva. In this review, current evidence for the bacterial invasion of the gingival tissue in periodontitis has been summarized, and the microbial and host factors that determine bacterial invasion of the gingiva have been reviewed.

Porphyromonas gingivalis W83 traffics via ICAM1 in microvascular endothelial cells and alters capillary organization in vivo

Objective: Microvascular dysfunction is a feature of periodontal disease. P. gingivalis, one of the most common oral bacteria present in gingival tissue biofilms, has also been identified in the gingival capillaries of patients with chronic periodontitis. We sought to determine the effect of P. gingivalis W83 infection on microvascular endothelium in vivo and in vitro. Methods and Results: Interdental papillae of rats with P. gingivalis-induced alveolar bone loss had a more dilated and denser subepithelial capillary network than uninfected controls. P. gingivalis W83 was detected in the epithelial layers, the subepithelial connective tissue matrix, and subgingival capillaries. P. gingivalis invaded human dermal microvascular endothelial cells (HD-MVECS) and persisted up termination (24 h). Colocalization analysis at 2.5, 6, and 24 h post-inoculation showed that 79-88% of internalized bacteria were in ICAM-1 positive endosomes, and 10-39% were in Rab5, Rab7, or LAMP1 positive compartments, but never in autophagosomes. Antibody-based blockade of ICAM-1 significantly reduced W83 invasion in HD-MVECS. P. gingivalis infected HD-MVECS were unable to form vascular networks in Matrigel. Conclusions: P. gingivalis perturbs microvascular endothelial function and invasion of these cells via ICAM-1 may be important for microbial persistence within tissues.

Catalase expression of Propionibacterium acnes may contribute to intracellular persistence of the bacterium in sinus macrophages of lymph nodes affected by sarcoidosis

Bacterial catalase is important for intracellular survival of the bacteria. This protein of Propionibacterium acnes, one of possible causes of sarcoidosis, induces hypersensitive Th1 immune responses in sarcoidosis patients. We examined catalase expression in cultured P. acnes isolated from 19 sarcoid and 18 control lymph nodes and immunohistochemical localization of the protein in lymph nodes from 43 sarcoidosis and 102 control patients using a novel P. acnes-specific antibody (PAC) that reacts with the catalase protein, together with the previously reported P. acnes-specific PAB and TIG antibodies. High catalase expression of P. acnes cells was found during stationary phase in more isolates from sarcoid than from non-sarcoid lymph nodes and was associated with bacterial survival under H₂O₂-induced oxidative stress. In many sarcoid and some control lymph nodes, catalase expression was detected at the outer margins of PAB-reactive Hamazaki-Wesenberg (HW) bodies in sinus macrophages, the same location as catalase expression on the surface of cultured P. acnes and the same distribution as bacterial cell membrane-bound lipoteichoic acid in HW bodies. Some or no catalase expression was detected in sarcoid granulomas with PAB reactivity or in clustered paracortical macrophages packed with many PAB-reactive small-round bodies. HW bodies expressing catalase may be persistent P. acnes in sinus macrophages whereas PAB-reactive small-round bodies with undetectable catalase may be activated P. acnes proliferating in paracortical macrophages. Intracellular proliferation of P. acnes in paracortical macrophages may lead to granuloma formation by this commensal bacterium in sarcoidosis patients with Th1 hypersensitivity to certain P. acnes antigens, including catalase.

Gingival crevicular fluid levels of SLIT3 are increased in periodontal disease

This study aims to investigate the levels of SLIT3 in gingival crevicular fluid (GCF) of healthy and periodontal disease subjects, and their correlations to periodontal disease. A total of 45 periodontal patients and 45 periodontally healthy volunteers were enrolled. The clinical parameters, radiographic bone loss and the levels of SLIT3, receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) in GCF were measured. The prevalences of Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia in subgingival plaque were also analyzed. The expression of SLIT3 and RANKL was detected in the periodontium of experimental periodontitis in rats and lipopolysaccharide (LPS)-induced mouse macrophage. The total amounts and concentrations of SLIT3 and RANKL were significantly higher in periodontitis than those in healthy, while the level of OPG was significantly lower (p < .05). Significant positive correlations were observed between the level of GCF SLIT3 and clinical attachment level and radiographic bone loss (p < .05). There existed a significant positive correlation between SLIT3 and RANKL (p < .05). Increased expression of SLIT3 and RANKL was observed in the periodontium of periodontal rats. SLIT3 expression was induced by LPS stimulation in macrophages. These results suggest that SLIT3 may act as a diagnostic indicator of periodontal disease and should be further investigated.