Surface morphology of pocket epithelium

NETs Are Double-Edged Swords with the Potential to Aggravate or Resolve Periodontal Inflammation

Periodontitis is a general term for diseases characterised by inflammatory destruction of tooth-supporting tissues, gradual destruction of the marginal periodontal ligament and resorption of alveolar bone. Early-onset periodontitis is due to disturbed neutrophil extracellular trap (NET) formation and clearance. Indeed, mutations that inactivate the cysteine proteases cathepsin C result in the massive periodontal damage seen in patients with deficient NET formation. In contrast, exaggerated NET formation due to polymorphonuclear neutrophil (PMN) hyper-responsiveness drives the pathology of late-onset periodontitis by damaging and ulcerating the gingival epithelium and retarding epithelial healing. Despite the gingival regeneration, periodontitis progression ends with almost complete loss of the periodontal ligament and subsequent tooth loss. Thus, NETs help to maintain periodontal health, and their dysregulation, either insufficiency or surplus, causes heavy periodontal pathology and edentulism.

Free Gingival Graft versus Mucograft: Histological Evaluation

INTRODUCTION:

The correction of the gingival recession is of esthetical and functional significance, but the tissue regeneration can only be confirmed by a histological examination.

AIM:

This study aims to make a comparison between the free gingival graft and the autograft.

MATERIAL AND METHODS:

This study included 24 patients with single and multiple gingival recessions. Twelve patients were treated with a free gingival graft and the other twelve with a micrograft. Six months after the surgical procedure, a micro-punch biopsy of the transplantation area was performed. The tissue was histologically evaluated, graded in 4 categories: immature, mature, fragmented and edematous collagen tissue. The elastic fibres were also examined and graded in three categories: with a normal structure, fragmented rare and fragmented multiplied.

RESULTS:

Regarding the type of collagen tissue that was present, there was a significant difference between the two groups of patients, with a larger number of patients treated with a micrograft showing a presence of mature tissue, compared to the patients treated with a free gingival graft. A larger number of patients in both of the groups displayed elastic fibres with a rare fragmented structure; 33.3% of the patients showed a normal structure; 50% demonstrated a normal structure.

CONCLUSION:

The patients treated with a free gingival graft showed a larger presence of fragmented collagen tissue and fragmented elastic fibres, whereas a mature tissue was predominantly present in the surgical area where a Geistlich Mucograft was placed.

Antimicrobial peptide gene expression in periodontitis patients: A pilot study

AIM

Antimicrobial peptides (AMPs) are one of the most active components of innate immunity and have characteristics that could place them at the heart of the pathogenesis of periodontal disease. This study investigated differences in the expression of AMP coding genes obtained using a simple harvesting technique, gingival smear, between two groups of patients: chronic periodontitis subjects versus healthy ones.

MATERIALS AND METHODS

Twenty-three patients were enrolled in two groups: 12 were diagnosed with moderate or severe generalized chronic periodontitis, and 11 were diagnosed as clinically healthy. Gingival smears were retrieved and studied using reverse transcription-quantitative PCR (RT-qPCR) after mRNA purification.

RESULTS

Fifteen gene expressions were obtained using real-time RT-qPCR. Three AMP genes, histatin 3 (HTN3), α-defensin 4 (DEFA4) and lysozyme C (LYZ), presented different expression levels in periodontitis patients compared with healthy subjects. The relative expression level of DEFA4 appeared to be a protective factor against periodontitis.

CONCLUSION

Gingival smears studied by RT-qPCR may be used to assess the expression of AMPs coding genes. A lack of expression of DEFA4 could be a potential indicator of periodontitis status.

Janus-Faced Neutrophil Extracellular Traps in Periodontitis

Periodontitis is characterized by PMN infiltration and formation of neutrophil extracellular traps (NETs). However, their functional role for periodontal health remains complex and partially understood. The main function of NETs appears to be evacuation of dental plaque pathogen-associated molecular patterns. The inability to produce NETs is concomitant with aggressive periodontitis. But in cases with exaggerated NET production, NETs are unable to maintain periodontal health and bystander damages occur. This pathology can be also demonstrated in animal models using lipopolysaccharide as PMN activator. The progress of periodontitis appears to be a consequence of the formation of gingival pockets obstructing the evacuation of both pathogen-associated and damage-associated molecular patterns, which are responsible for the self-perpetuation of inflammation. Thus, besides the pathogenic effects of the periodontal bacteria, the dysregulation of PMN activation appears to play a main role in the periodontal pathology. Consequently, modulation of PMN activation might be a useful approach to periodontal therapy.

[Oral care recommendations for patients with oral autoimmune bullous diseases]

BACKGROUND

Autoimmune bullous diseases (AIBD) may cause chronic oral lesions that progress insidiously.

AIMS

To provide recommendations for optimal oral-dental management of patients presenting AIBD with oral involvement.

PATIENTS AND METHODS

In the absence of scientific studies with high levels of proof, these recommendations have been drawn up at two meetings by a committee of experts on AIBD comprising 7 dermatologists, 1 stomatologist, 1 maxillofacial surgeon, 2 odontologists and 4 parodontologists.

RESULTS

The oral lesions associated with AIBD may be classified into three grades of severity: severe (generalised erosive gingivitis affecting at least 30% of dental sites), moderate (localised erosive gingivitis affecting less than 30% of dental sites) and controlled (no erosive oral lesions). Good oral-dental hygiene suited to the severity of the oral lesions, must be practised continually by these patients so as to avoid the formation of dental plaque, which aggravates symptoms. Dental and parodontal care must be considered in accordance with the severity grade of the oral lesions: in severe cases, the dental plaque must be eliminated manually with a curette, but several types of care (descaling, treatment for tooth decay, non-urgent extractions, etc.) must be suspended until the grade of severity is moderate or until the disease is stabilised.

EBV infection is common in gingival epithelial cells of the periodontium and worsens during chronic periodontitis

An amplifying role for oral epithelial cells (ECs) in Epstein-Barr Virus (EBV) infection has been postulated to explain oral viral shedding. However, while lytic or latent EBV infections of oro/nasopharyngeal ECs are commonly detected under pathological conditions, detection of EBV-infected ECs in healthy conditions is very rare. In this study, a simple non-surgical tissue sampling procedure was used to investigate EBV infection in the periodontal epithelium that surrounds and attaches teeth to the gingiva. Surprisingly, we observed that the gingival ECs of the periodontium (pECs) are commonly infected with EBV and may serve as an important oral reservoir of latently EBV-infected cells. We also found that the basal level of epithelial EBV-infection is significantly increased in chronic periodontitis, a common inflammatory disease that undermines the integrity of tooth-supporting tissues. Moreover, the level of EBV infection was found to correlate with disease severity. In inflamed tissues, EBV-infected pECs appear to be prone to apoptosis and to produce larger amounts of CCL20, a pivotal inflammatory chemokine that controls tissue infiltration by immune cells. Our discovery that the periodontal epithelium is a major site of latent EBV infection sheds a new light on EBV persistence in healthy carriers and on the role of this ubiquitous virus in periodontitis. Moreover, the identification of this easily accessible site of latent infection may encourage new approaches to investigate and monitor other EBV-associated disorders.

Smad2 is involved in the apoptosis of murine gingival junctional epithelium associated with inhibition of Bcl-2

OBJECTIVE

Gingival junctional epithelium (JE) actively contributes to the homeostasis of the periodontium. Altered activation of TGF-β signalling is implicated in the epithelium from chronic periodontitis. However, little is known about the effects of TGF-β signalling on the JE. In this study, we investigated the relationship between Smad2, which plays an important role in mediating TGF-β signal, and induction of apoptosis in the JE.

METHODS

K14-Smad2 transgenic mice were used to observe the effect of over-expression of Smad2 driven by CK14 promoter in the JE. We performed TUNEL technique to evaluate the epithelial apoptosis. Expression of apoptosis related genes was examined using real-time PCR and immunofluorescence.

RESULTS

K14-Smad2 mice showed an increased number of phospho-Smad2 positive JE cells associated with an increase in TGF-β1 expression. K14-Smad2 mice have a significantly higher percentage of TUNEL positive cells in the JE. Immunofluorescence double labelling revealed that TUNEL positive cells showed immunoreactivity to phospho-Smad2. Real-time PCR analysis of apoptosis related gene expression provided evidence of lower expression of Bcl-2 in the gingival tissue from K14-Smad2 mice. There was a strong positive reaction for Bcl-2 protein in the junctional epithelium of wild type mice, while the gingival tissue of K14-Smad2 transgenic mice had only a faint signal for Bcl-2.

CONCLUSIONS

The present study provided evidence that Smad2 plays a crucial role in the induction of apoptosis in gingival JE through inhibition of Bcl-2.

Host-bacteria crosstalk at the dentogingival junction

The dentogingival junction is of crucial importance in periodontal host defense both structurally and functionally. Oral bacteria exert a constant challenge to the host cells and tissues at the dentogingival junction. The host response is set up to eliminate the pathogens by the innate and adaptive defense mechanisms. In health, the commensal bacteria and the host defense mechanisms are in a dynamic steady state. During periodontal disease progression, the dental bacterial plaque, junctional epithelium (JE), inflammatory cells, connective tissue, and bone all go through a series of changes. The tissue homeostasis is turned into tissue destruction and progression of periodontitis. The classical study of Slots showed that in the bacterial plaque, the most remarkable change is the shift from gram-positive aerobic and facultatively anaerobic flora to a predominantly gram-negative and anaerobic flora. This has been later confirmed by several other studies. Furthermore, not only the shift of the bacterial flora to a more pathogenic one, but also bacterial growth as a biofilm on the tooth surface, allows the bacteria to communicate with each other and exert their virulence aimed at favoring their growth. This paper focuses on host-bacteria crosstalk at the dentogingival junction and the models studying it in vitro.

Filifactor alocis interactions with gingival epithelial cells

An association between the gram-positive anaerobe Filifactor alocis and periodontal disease has recently emerged; however, possible pathogenic mechanisms have not been investigated. In this study we examined the responses of primary cultures of gingival epithelial cells (GECs) to infection with F. alocis. Secretion of the pro-inflammatory cytokines interleukin-1β, interleukin-6 and tumor necrosis factor-α from GECs was stimulated by F. alocis infection. F. alocis also induced apoptosis in GECs through pathways that involved caspase-3 but not caspase-9. Apoptosis was coincident with inhibition of mitogen-activated protein kinase kinase (MEK) activation. These results show that F. alocis has characteristics in common with established periodontal pathogens and has the potential to contribute to periodontal tissue destruction.

Systemic endotoxin levels in chronic indolent periodontal infections

BACKGROUND AND OBJECTIVE

Periodontal disease has been linked with an increased risk of various systemic diseases. A plausible biologic explanation for this link includes the opportunity for oral pathogens to translocate to the circulation as a result of breakdown in integrity of the oral epithelium. This study refined a methodology used to detect endotoxin activity in the serum of subjects with indolent periodontal infections.

MATERIAL AND METHODS

The QCL Kinetic Chromogenic Assay (Cambrex) is a kinetic measure of endotoxin activity. Sera from 211 pregnant women with periodontitis enrolled in the Obstetrics and Periodontal Therapy Trial were used to develop the assay further and to evaluate the detection of endotoxin activity that might accompany a low-level bacteremia in chronic periodontitis.

RESULTS

We optimized the system to increase the sensitivity and reproducibility of the assay. The refined system was able to detect endotoxin activity in serum at > 0.0125 EU/mL. At baseline (13-16 wk of gestation), 35.5% of the women were positive for endotoxin activity (1.62 +/- 2.21; range: 0.38-15 EU/mL).

CONCLUSION

This report describes a sensitive measure of endotoxin activity in serum. The procedure allowed us to document levels of this microbial virulence factor in serum of individuals with indolent infections such as periodontal disease.

Beyond good and evil in the oral cavity: insights into host-microbe relationships derived from transcriptional profiling of gingival cells

In many instances, the encounter between host and microbial cells, through a long-standing evolutionary association, can be a balanced interaction whereby both cell types co-exist and inflict a minimal degree of harm on each other. In the oral cavity, despite the presence of large numbers of diverse organisms, health is the most frequent status. Disease will ensue only when the host-microbe balance is disrupted on a cellular and molecular level. With the advent of microarrays, it is now possible to monitor the responses of host cells to bacterial challenge on a global scale. However, microarray data are known to be inherently noisy, which is caused in part by their great sensitivity. Hence, we will address several important general considerations required to maximize the significance of microarray analysis in depicting relevant host-microbe interactions faithfully. Several advantages and limitations of microarray analysis that may have a direct impact on the significance of array data are highlighted and discussed. Further, this review revisits and contextualizes recent transcriptional profiles that were originally generated for the specific study of intricate cellular interactions between gingival cells and 4 important plaque micro-organisms. To our knowledge, this is the first report that systematically investigates the cellular responses of a cell line to challenge by 4 different micro-organisms. Of particular relevance to the oral cavity, the model bacteria span the entire spectrum of documented pathogenic potential, from commensal to opportunistic to overtly pathogenic. These studies provide a molecular basis for the complex and dynamic interaction between the oral microflora and its host, which may lead, ultimately, to the development of novel, rational, and practical therapeutic, prophylactic, and diagnostic applications.

Expression of the Receptor of Advanced Glycation End Products in the Gingival Tissue of Smokers With Generalized Periodontal Disease and After Nornicotine Induction in Primary Gingival Epithelial Cells

BACKGROUND

The association between smoking and periodontal disease is well established; however, the mechanism by which smoking augments the destruction of periodontal tissue is not clear. We hypothesize that smoking is related to an increased expression of receptor of advanced glycation end products (RAGE) in gingival tissues of smokers.

METHODS

Gingival biopsies from five smokers and five age- and gender-matched non-smokers were examined. In addition, gingival epithelial cells (GECs) were reacted with 1 muM nornicotine for 4, 16, 24, and 48 hours for mRNA for RAGE and an additional 72 hours for protein expression. RAGE mRNA was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR), and expression of RAGE at the protein level in GECs was studied with Western blots.

RESULTS

In the gingival biopsies from all 10 subjects, RT-PCR with RAGE-specific primers produced a band of the predicted size. For all pairs, the smoker biopsies expressed a greater level of RAGE compared to the matched non-smokers. When viewed as groups, analysis of the band intensity indicated that RAGE mRNA in smokers was approximately 1.4-fold of the expression in non-smokers (Wilcoxon test; P = 0.031). In GECs treated with nornicotine, there was a time-dependent increase in RAGE expression up to two-fold at 48 hours. RAGE protein levels initially were reduced but increased to 1.4-fold after 48 hours.

CONCLUSION

The ability of nornicotine to elevate RAGE expression in GECs, along with increased RAGE expression in inflamed gingival tissue from smokers, indicates that RAGE may be associated with periodontal disease linked to smoking.

Visualization of neutrophil extracellular traps in TEM

Neutrophil extracellular traps (NETs) have recently been described as an important innate defence mechanism in inflammation. However, routine electron microscopic staining techniques faintly stain NETs and are therefore insufficient for enabling a distinction between these and the host cell debris as well as proteins regularly present at the site of inflammation. In order to test suitable electron microscopic staining techniques, NETs induced ex vivo via phorbol myristate were absorbed on formvar. Four types of drop-on-grid positive staining were used: osmium tetroxide (Os), osmium tetroxide-uranyl acetate-lead citrate (Os-U-Pb), ruthenium red-osmium tetroxide (RR-OsO4), and cuprolinic blue enhanced by sodium tungstate (CB-WO4). We observed no staining of NETs using Os, faint staining with Os-U-Pb, better but still weak staining with CB-WO4 and outstanding staining with RR-OsO4. Furthermore, RR-OsO4 staining also enables the observation of bacterial fimbriae-mediated adhesion, which is possibly responsible for the ability of NETs to bind bacteria. Thus, the offered RR-OsO4 staining technique may facilitate the study of the NETs-bacterial interactions.