Neutrophil-mediated tissue injury in periodontal disease pathogenesis: findings from localized aggressive periodontitis

Grade C Molar-Incisor Pattern Periodontitis in Young Adults: What Have We Learned So Far?

Grade C molar-incisor pattern periodontitis (C-MIP) is a disease that affects specific teeth with an early onset and aggressive progression. It occurs in systemically healthy patients, mostly African descendants, at an early age, with familial involvement, minimal biofilm accumulation, and minor inflammation. Severe and rapidly progressive bone loss is observed around the first molars and incisors. This clinical condition has been usually diagnosed in children and young adults with permanent dentition under 30 years of age. However, this disease can also affect the primary dentition, which is not as frequently discussed in the literature. Radiographic records have shown that most patients diagnosed in the permanent dentition already presented disease signs in the primary dentition. A hyperresponsive immunological profile is observed in local (gingival crevicular fluid-GCF) and systemic environments. Siblings have also displayed a heightened inflammatory profile even without clinical signs of disease. A. actinomycetemcomitans has been classified as a key pathogen in C-MIP in both dentitions. Scaling and root planning associated with systemic antibiotics is the current gold standard to treat C-MIP, leading to GCF biomarker reduction, some systemic inflammatory response modulation and microbiome profile changes to a healthy-site profile. Further studies should focus on other possible disease-contributing risk factors.

Periodontal inflammatory and microbial profiles in healthy young African Americans and Caucasians

AIM

This study aimed to compare microbial and inflammatory profiles in periodontally/systemically healthy African American (AA) and Caucasian (C) individuals.

MATERIALS AND METHODS

Thirty-seven C and 46 AA aged from 5 to 25 years were evaluated regarding periodontal disease, caries, microbial subgingival profile via 16-s sequencing, as well as salivary and gingival crevicular fluid (GCF) inflammatory profile via multiplex assay.

RESULTS

Greater probing depth percentage was detected in AA (p = .0075), while a higher percentage of caries index (p = .0069) and decayed, missing, filled teeth (DMFT) index (p = .0089) was observed in C, after adjusting for number of teeth, sex and age. Salivary levels of IL-6, IL-8 and TNFα were higher for C, whereas GCF levels of eotaxin, IL-12p40, IL-12p70, IL-2 and MIP-1α were higher in AA (p < .05). Different microbial profiles were observed between the races (p = .02). AA presented higher abundance of periodontopathogens (such as Tanerella forsythia, Treponema denticola, Filifactor alocis, among others), and C presented more caries-associated bacteria (such as Streptococcus mutans and Prevotella species). Bacillaceae and Lactobacillus species were associated with higher DMFT index, whereas Fusobacterium and Tanerella species with periodontal disease parameters.

CONCLUSIONS

A different inflammatory and bacterial profile was observed between healthy AA and C, which may predispose these races to higher susceptibility to specific oral diseases.

The Role of Sulfhydryl (Thiols) Groups in Oral and Periodontal Diseases

AIM

The sulfhydryl (thiols) group of glutathione plays an important role in the neutralization of foreign organic compounds and the reduction in peroxides. The purpose of the study is to evaluate the concentration of sulfhydryl groups in the gingival tissue of healthy individuals and those with gingivitis or periodontitis, and to examine the differences between these groups.

MATERIAL AND METHODS

To assess the concentration of sulfhydryl groups (thiols) in the gingival tissue of healthy individuals and those with gingivitis or periodontitis, we used spectrophotometric analysis using dithionitrobenzoate (DTNB) as a reagent to measure the accessible sulfhydryl groups present in gingival tissue proteins. The sample was divided into three distinct groups: individuals with periodontal health, gingivitis, and periodontitis, and different indices were used to assess the periodontal status of the participants. Next, a statistical analysis was conducted to compare the concentrations of sulfhydryl groups among the different groups of patients.

CONCLUSIONS

The results of this study showed significantly decreased levels of sulfhydryl (thiols) groups in gingival tissue from patients with gingivitis and periodontitis, compared with healthy people (control group). These results confirm the role of sulfhydryl (thiols) groups in defense against free radicals. They share a significant role in detoxification, signal transduction, apoptosis, and various other functions at the molecular level.

Osteoinduction and osteoimmunology: Emerging concepts

The recognition and importance of immune cells during bone regeneration, including around bone biomaterials, has led to the development of an entire field termed "osteoimmunology," which focuses on the connection and interplay between the skeletal system and immune cells. Most studies have focused on the "osteogenic" capacity of various types of bone biomaterials, and much less focus has been placed on immune cells despite being the first cell type in contact with implantable devices. Thus, the amount of literature generated to date on this topic makes it challenging to extract needed information. This review article serves as a guide highlighting advancements made in the field of osteoimmunology emphasizing the role of the osteoimmunomodulatory properties of biomaterials and their impact on osteoinduction. First, the various immune cell types involved in bone biomaterial integration are discussed, including the prominent role of osteal macrophages (OsteoMacs) during bone regeneration. Thereafter, key biomaterial properties, including topography, wettability, surface charge, and adsorption of cytokines, growth factors, ions, and other bioactive molecules, are discussed in terms of their impact on immune responses. These findings highlight and recognize the importance of the immune system and osteoimmunology, leading to a shift in the traditional models used to understand and evaluate biomaterials for bone regeneration.

Age-related bone diseases: Role of inflammaging

Bone aging is characterized by an imbalance in the physiological and pathological processes of osteogenesis, osteoclastogenesis, adipogenesis, and chondrogenesis, resulting in exacerbated bone loss and the development of age-related bone diseases, including osteoporosis, osteoarthritis, rheumatoid arthritis, and periodontitis. Inflammaging, a novel concept in the field of aging research, pertains to the persistent and gradual escalation of pro-inflammatory reactions during the aging process. This phenomenon is distinguished by its low intensity, systemic nature, absence of symptoms, and potential for management. The mechanisms by which inflammaging contribute to age-related chronic diseases, particularly in the context of age-related bone diseases, remain unclear. The precise manner in which systemic inflammation induces bone aging and consequently contributes to the development of age-related bone diseases has yet to be fully elucidated. This article primarily examines the mechanisms underlying inflammaging and its association with age-related bone diseases, to elucidate the potential mechanisms of inflammaging in age-related bone diseases and offer insights for developing preventive and therapeutic strategies for such conditions.

Quantification and comparison of salivary neutrophils in periodontal health and disease

Background

Neutrophils continuously migrate into the oral cavity from various sources like gingival crevicular fluid and saliva both in health and in inflammation. The migration of the neutrophils into the various tissues and into the oral cavity occurs when the host microbial interplay tips the balance favoring the initiation of the inflammatory and immune reactions which depending on the amount of the microbial load results in the development of acute and chronic infections in the susceptible host.

Aim

The present study was designed to quantify and compare the oral salivary neutrophil levels in patients with gingivitis and chronic and aggressive periodontitis as well as in healthy controls, before and after scaling and root planing (SRP) and to compare the difference within the selected study groups.

Materials and Methods

Forty subjects were classified into four groups, that is, healthy controls, gingivitis, and chronic and aggressive periodontitis. Oral rinse samples were collected using Hank's balanced salt solution from each patient before and after phase I periodontal therapy. Cells in the rinse samples were stained with Acridine orange, and neutrophil counts were carried out using a fluorescence microscope and a hemocytometer.

Results

Baseline oral salivary neutrophil levels were maximum in the chronic periodontitis group followed by the aggressive group and then the gingivitis group. Oral salivary neutrophil levels also positively correlated to probing pocket depth, plaque index, calculus index, and gingival index in all four study groups. Maximum reduction in the oral salivary neutrophil levels after phase I periodontal therapy was seen in the gingivitis group.

Conclusion

From our study, we conclude that the oral salivary neutrophil levels decreased significantly after SRP. Estimation of changes in the oral salivary neutrophil levels has the potential to aid in monitoring treatment outcomes. Thus, it suggests that it could be used as a simple, noninvasive laboratory technique to monitor the periodontal status and disease progression.

Biomarkers for diagnosis of stage III, grade C with molar incisor pattern periodontitis in children and young adults: a systematic review and meta-analysis

AIM

To explore the existing salivary, gingival crevicular fluid (GCF), blood, and serum biomarkers associated with grade C molar-incisor pattern (C/MIP) periodontitis in systemically healthy children and young adults.

MATERIALS AND METHODS

Cross-sectional, case-control, and cohort studies on stage III grade C periodontitis or former equivalent diagnosis with analysis of molecular biomarkers in saliva, GCF, blood, or serum were retrieved from six databases and screened based on the eligibility criteria. The risk of bias in included studies was evaluated. Meta-analysis was planned for biomarkers assessed using the same detection methods and sample type in at least two papers.

RESULTS

Out of 5621 studies identified at initial screening, 28 papers were included in the qualitative analysis of which 2 were eligible for meta-analysis for IgG in serum samples. Eighty-seven biomarkers were assessed with the majority being higher in cases than in controls. Only the meta-analysis of total serum IgG with low heterogeneity value revealed a significant increase in its levels in C/MIPs compared to controls (standardised mean difference: 1.08; 95% CI: 0.76, 1.40).

CONCLUSION

There is a paucity of data on biomarkers associated with molar-incisor pattern periodontitis. Although serum IgG levels are raised, other more specific biomarkers in saliva, GCF, and blood/serum may be promising but require further investigation.

Electroacupuncture regulates macrophage, neutrophil, and oral microbiota to alleviate alveolar bone loss and inflammation in experimental ligature-induced periodontitis

AIM

Electroacupuncture (EA) regulates distant body physiology through somatic sensory autonomic reflexes, balances the microbiome, and can promote the release of immune cells into bloodstream, thereby inhibiting severe systemic inflammation. This makes it possible to use EA as an integrated treatment for periodontitis.

MATERIALS AND METHODS

In this study, EA was applied to the ST36 acupoints in a ligature-induced periodontitis (LIP) mouse model. Then the effects of EA on periodontal myeloid cells, cytokines, and the microbiome were comprehensively analysed using flow cytometry, quantitative Polymerase Chain Reaction (PCR), and 16 S sequencing.

RESULTS

Results demonstrated that EA could significantly relieve periodontal bone resorption. EA also suppressed the infiltration of macrophages and neutrophils, reduced gene expression of the pro-inflammatory cytokines IL-1β, IL-6, IL-17 and TNF-α, and increased expression of the anti-inflammatory factors IL-4 and IL-10 in periodontal tissues. Moreover, composition of the periodontal microbiome was regulated by EA, finding that complex of microbiota, including supragingival Veillonella, subgingival Streptococcus, and subgingival Erysipelatoclostridium, were significantly reduced. Meanwhile, nitrate and nitrate-related activities of subgingival microbiota were reversed. Network analysis revealed close relationships among Veillonella, Streptococcus, and Bacteroides.

CONCLUSIONS

Our study indicates that EA can effectively alleviate inflammation and bone resorption in LIP mice, potentially via the regulation of myeloid cells, cytokines, and periodontal microbiome.

The role of non-steroidal anti-inflammatory drugs as adjuncts to periodontal treatment and in periodontal regeneration

Periodontitis is the sixth most prevalent chronic disease globally and places significant burdens on societies and economies worldwide. Behavioral modification, risk factor control, coupled with cause-related therapy have been the "gold standard" treatment for managing periodontitis. Given that host inflammatory and immunological responses play critical roles in the pathogenesis of periodontitis and impact treatment responses, several adjunctive strategies aimed at modulating host responses and improving the results of periodontal therapy and maintenance have been proposed. Of the many pharmacological host modulators, we focused on non-steroidal anti-inflammatory drugs (NSAIDs), due to their long history and extensive use in relieving inflammation and pain and reducing platelet aggregation. NSAIDs have been routinely indicated for treating rheumatic fever and osteoarthritis and utilized for the prevention of cardiovascular events. Although several efforts have been made to incorporate NSAIDs into the treatment of periodontitis, their effects on periodontal health remain poorly characterized, and concerns over the risk-benefit ratio were also raised. Moreover, there is emerging evidence highlighting the potential of NSAIDs, especially aspirin, for use in periodontal regeneration. This review summarizes and discusses the use of NSAIDs in various aspects of periodontal therapy and regeneration, demonstrating that the benefits of NSAIDs as adjuncts to conventional periodontal therapy remain controversial. More recent evidence suggests a promising role for NSAIDs in periodontal tissue engineering and regeneration.

Healing effects of monomer and dimer resveratrol in a mouse periodontitis model

Background

The antioxidant and anti-inflammatory effects of resveratrol have been reported previously. Particularly, monomeric trans-resveratrol has been demonstrated to produce positive effects in various pathological processes. We reported previously that resveratrol dimer-rich melinjo extract, among others, caused bone healing, decreased local oxidative damage, and activated antioxidants nuclear factor erythroid 2-related factor 2 (Nrf2) pathways in a mouse model of experimentally induced periodontitis (EP). This study aimed to compare the bone-healing effects of the resveratrol monomer to the resveratrol dimer (gnetin C found in melinjo seed extract) in a model of EP and investigate the involvement of Nrf2 for effects of either form of resveratrol.

Methods

EP was induced experimentally in mice by placement of a 9 − 0 silk ligature around the left second molar. Mice received 10 mg/kg of either resveratrol monomer or dimer intraperitoneally on day 15 after induction of EP. The bone level around the ligated teeth was measured over time, and levels of proinflammatory cytokines and oxidative stress were measured in the periodontal tissues around the ligated teeth.

Results

Resveratrol dimer induced greater periodontal bone healing as compared to that related to use of the resveratrol monomer. It appears that healing of periodontal bone in either group was likely related to master regulation of antioxidant nuclear factor erythroid 2-related factor 2 (Nrf2) significantly. Downregulation of IL-1β, a proinflammatory cytokine was also demonstrated in the resveratrol dimer group.

Conclusion

Our results showed that administration of resveratrol in either dimer form or the monomeric form reduced periodontal bone loss with greater inhibition of bone loss being demonstrated in the dimer group as compared to the monomer group and that these effects were related in all likelihood to decreased oxidative stress and hence reduction in local inflammation.

Ferroptosis: A New Development Trend in Periodontitis

Periodontitis is a chronic inflammatory disease associated with bacterial biofilm. It is characterized by loss of periodontal support tissue and has long been considered as a "silent disease". Because it is difficult to prevent and has a health impact that can not be ignored, researchers have been focusing on a mechanism-based treatment model. Ferroptosis is an iron-dependent regulatory form of cell death, that directly or indirectly affects glutathione peroxidase through different signaling pathways, resulting in a decrease in cell antioxidant capacity, accumulation of reactive oxygen species and lipid peroxidation, which cause oxidative cell death and tissue damage. Recently, some studies have proven that iron overload, oxidative stress, and lipid peroxidation exist in the process of periodontitis. Based on this, this article reviews the relationship between periodontitis and ferroptosis, in order to provide a theoretical reference for future research on the prevention and treatment of periodontal disease.

Periodontitis and implant complications in diabetes

Epidemiologic evidence indicates that periodontitis is more frequent in patients with uncontrolled diabetes mellitus than in healthy controls, suggesting that it could be considered the "sixth complication" of diabetes. Actually, diabetes mellitus and periodontitis are two extraordinarily prevalent chronic diseases that share a number of comorbidities all converging toward an increased risk of cardiovascular disease. Periodontal treatment has recently been shown to have the potential to improve the metabolic control of diabetes, although long-term studies are lacking. Uncontrolled diabetes also seems to affect the response to periodontal treatment, as well as the risk to develop peri-implant diseases. Mechanisms of associations between diabetes mellitus and periodontal disease include the release of advanced glycation end products as a result of hyperglycemia and a range of shared predisposing factors of genetic, microbial, and lifestyle nature. This review discusses the evidence for the risk of periodontal and peri-implant disease in diabetic patients and the potential role of the dental professional in the diabetes-periodontal interface.

Medicinal Plants Used as an Alternative to Treat Gingivitis and Periodontitis

For various ailments, natural remedies have been traditionally used. To defend against common disorders, medicinal plants are progressively used as nutritional supplements. Gingivitis and periodontitis are widespread and can affect most of the world's population. Gingivitis is a very common, nondestructive inflammatory disease of gums that causes redness and irritation of the gingiva (gums), but periodontitis causes permanent damage to teeth' subsidiary structures. Herbal medicines are getting popular for the treatment of such types of disorders due to being economical with their medicinal effectiveness, compatibility, and nontoxicity. Traditional chemical therapies can cause cell toxicity along with their disease-curing effects. In this article, we discussed the medicinal plants that can be used as an alternative for the treatment of gingivitis (early-stage gum disease) and periodontitis (chronic-stage gum disease).

The neutrophil elastase-upregulated placenta growth factor promotes the pathogenesis and progression of periodontal disease

BACKGROUND

Periodontal disease is a chronic inflammatory disease. Given its high prevalence, especially in aging population, the detailed mechanisms about pathogenesis of periodontal disease are important issues for study. Neutrophil firstly infiltrates to periodontal disease-associated pathogen loci and amplifies the inflammatory response for host defense. However, excessive neutrophil-secreted neutrophil elastase (NE) damages the affected gingival. In lung and esophageal epithelium, NE had been proved to upregulate several growth factors including placenta growth factor (PGF). PGF is an angiogenic factor with proinflammatory properties, which mediates the progression of inflammatory disease. Therefore, we hypothesize excessive NE upregulates PGF and participates in the pathogenesis and progression of periodontal disease.

METHODS

In gingival epithelial cells (GEC), growth factors array demonstrated NE-increased growth factors and further be corroborated by Western blot assay and ELISA. The GEC inflammation was evaluated by ELISA. In mice, the immunohistochemistry results demonstrated ligature implantation-induced neutrophil infiltration and growth factor upregulation. By multiplex assay, the ligature-induced proinflammatory cytokines level in gingival crevicular fluid (GCF) were evaluated. Finally, alveolar bone absorption was analyzed by micro-CT images and H &amp; E staining.

RESULTS

NE upregulated PGF expression and secretion in GEC. PGF promoted GEC to secret IL-1β, IL-6, and TNF-α in GCF In periodontal disease animal model, ligature implantation triggered NE infiltration and PGF expression. Blockade of PGF attenuated the ligature implantation-induced IL-1β, IL-6, TNF-α and MIP-2 secretion and ameliorated the alveolar bone loss in mice.

CONCLUSION

In conclusion, the NE-induced PGF triggers gingival epithelium inflammation and promotes the pathogenesis and progression of periodontal disease.

CD18 Mediates Neutrophil Imperviousness to the Aggregatibacter actinomycetemcomitans JP2 Clone in Molar-Incisor Pattern Periodontitis

Introduction

Molar-incisor pattern periodontitis (MIPP) in the absence of significant local risk factors or systemic disease, is a rare, early onset periodontal disease phenotype, with 0.5% to 2.5% global prevalence. The condition is characterized by impaired neutrophil function and persistent Aggregatibacter actinomycetemcomitans (JP2 clone) infection. The aim of this study was to characterize neutrophil functional responses to JP2 and to investigate the neutrophil receptors involved.

Materials and Methods

Neutrophils were obtained from whole blood samples of periodontally healthy and MIPP subjects and incubated with the JP2 clone or a non-JP2 clone of A. actinomycetemcomitans. Bacterial survival was tested by blood agar culture; neutrophil death was tested with propidium iodide and flow cytometry; Reactive oxygen production (ROS) was measured with 2′,7′-dichlorofluorescein diacetate and a fluorescence plate reader; the cytokinome was analysed using an array profiler, ELISA and RT-PCR. Receptors binding to JP2 were isolated using a novel immunoprecipitation assay and validated functionally using specific blocking antibodies.

Results

JP2 and non-JP2 survival was comparable between all the neutrophil groups. Resistance to neutrophil necrosis following exposure to JP2 was significantly lower in the MIPP group, than in all the other groups (p<0.0001). Conversely, MIPP neutrophils showed lower levels of ROS production in response to JP2 infection compared with that of healthy neutrophils (p<0.001). Furthermore, significantly lower levels of cytokines, such as IL8, IL10 and TNFα, were observed during JP2 incubation with MIPP neutrophils than upon incubation with periodontally healthy neutrophils. Various proteins expressed on neutrophils bind to JP2. Of these, CD18 was found to mediate neutrophil necrosis. The CD18 receptor on MIPP neutrophils acts differently from that on periodontally healthy patients neutrophils, and appears to reflect differential neutrophil reactions to JP2.

Conclusion

This study portrays a fundamental difference in neutrophil response to JP2 infection between periodontally healthy and MIPP patients. This was evident in the resistance to necrosis, and lower ROS and cytokine production, despite the persistent presence of viable JP2. Whilst in periodontally healthy neutrophils, JP2 binds to CD18 on cell surfaces, this is not the case in MIPP neutrophils, suggesting a potential role for CD18 in the periodontal susceptibility of MIPP patients.

Complement component 3 (C3) and its activation split-products in saliva associates with periodontitis

BACKGROUND AND OBJECTIVE

Periodontitis (PD) is classified by grades A through C according to the risk of further progression, PD grade C (PD-C) being the most severe progressing form. It is a matter of controversy, whether the disease activity observed in PD-C is due to impaired immune reactivity towards bacteria embedded in biofilms or a hyper-reactive immune response causing tissue damage as a bystander phenomenon. Little is known about the role of complement in this respect.

MATERIALS AND METHODS

Plasma and unstimulated saliva samples were collected from patients with PD-B (n = 34) or -C (n = 27) and healthy controls (HCs) (n = 28). Salivary and plasma levels of total C3, C3c and C3dg were quantified using sandwich ELISA.

RESULTS

Salivary levels of total C3 and C3dg were elevated in PD-B and PD-C patients compared to HCs (both p< 0.05), while the levels of C3c were elevated in PD-C compared to HCs. Plasma levels of C3c were higher in PD-B patients than in HCs (p< 0.05).

CONCLUSION

PD-B and PD-C patients show increased complement activation compared to HCs, but no difference was found between the two disease grades. PD-B, but not PD-C, is associated with increased systemic complement activation as assessed by C3c in plasma. This article is protected by copyright. All rights reserved.

Fixed Prosthetic Restorations and Periodontal Health: A Narrative Review

Periodontal health plays an important role in the longevity of prosthodontic restorations. The issues of comparative assessment of prosthetic constructions are complicated and not fully understood. The aim of this article is to review and present the current knowledge regarding the various technical, clinical, and molecular aspects of different prosthetic biomaterials and highlight the interactions between periodontal health and prosthetic restorations. Articles on periodontal health and fixed dental prostheses were searched using the keywords “zirconium”, “CAD/CAM”, “dental ceramics”, “metal–ceramics”, “margin fit”, “crown”, “fixed dental prostheses”, “periodontium”, and “margin gap” in PubMed/Medline, Scopus, Google Scholar, and Science Direct. Further search criteria included being published in English, and between January 1981 and September 2021. Then, relevant articles were selected, included, and critically analyzed in this review. The margin of discrepancy results in the enhanced accumulation of dental biofilm, microleakage, hypersensitivity, margin discoloration, increased gingival crevicular fluid flow (GCF), recurrent caries, pulp infection and, lastly, periodontal lesion and bone loss, which can lead to the failure of prosthetic treatment. Before starting prosthetic treatment, the condition of the periodontal tissues should be assessed for their oral hygiene status, and gingival and periodontal conditions. Zirconium-based restorations made from computer-aided design and computer-aided manufacturing (CAD/CAM) technology provide better results, in terms of marginal fit, inflammation reduction, maintenance, and the restoration of periodontal health and oral hygiene, compared to constructions made by conventional methods, and from other alloys. Compared to subgingival margins, supragingival margins offer better oral hygiene, which can be maintained and does not lead to secondary caries or periodontal disease.

Nociceptor Neurons Magnify Host Responses to Aggravate Periodontitis

Periodontitis is a highly prevalent chronic inflammatory disease that progressively destroys the structures supporting teeth, leading to tooth loss. Periodontal tissue is innervated by abundant pain-sensing primary afferents expressing neuropeptides and transient receptor potential vanilloid 1 (TRPV1). However, the roles of nociceptive nerves in periodontitis and bone destruction are controversial. The placement of ligature around the maxillary second molar or the oral inoculation of pathogenic bacteria induced alveolar bone destruction in mice. Chemical ablation of nociceptive neurons in the trigeminal ganglia achieved by intraganglionic injection of resiniferatoxin decreased bone loss in mouse models of experimental periodontitis. Consistently, ablation of nociceptive neurons decreased the number of osteoclasts in alveolar bone under periodontitis. The roles of nociceptors were also determined by the functional inhibition of TRPV1-expressing trigeminal afferents using an inhibitory designer receptor exclusively activated by designer drugs (DREADD) receptor. Noninvasive chemogenetic functional silencing of TRPV1-expressing trigeminal afferents not only decreased induction but also reduced the progression of bone loss in periodontitis. The infiltration of leukocytes and neutrophils to the periodontium increased at the site of ligature, which was accompanied by increased amount of proinflammatory cytokines, such as receptor activator of nuclear factor κΒ ligand, tumor necrosis factor, and interleukin 1β. The extents of increase in immune cell infiltration and cytokines were significantly lower in mice with nociceptor ablation. In contrast, the ablation of nociceptors did not alter the periodontal microbiome under the conditions of control and periodontitis. Altogether, these results indicate that TRPV1-expressing afferents increase bone destruction in periodontitis by promoting hyperactive host responses in the periodontium. We suggest that specific targeting of neuroimmune and neuroskeletal regulation can offer promising therapeutic targets for periodontitis supplementing conventional treatments.

TAS2R16 Activation Suppresses LPS-Induced Cytokine Expression in Human Gingival Fibroblasts

Sustained and non-resolved inflammation is a characteristic of periodontitis. Upon acute inflammation, gingival fibroblasts release cytokines to recruit immune cells to counter environmental stimuli. The intricate regulation of pro-inflammatory signaling pathways, such as NF-κB, is necessary to maintain periodontal homeostasis. Nonetheless, how inflammation is resolved has not yet been elucidated. In this study, 22 subtypes of taste receptor family 2 (TAS2Rs), as well as the downstream machineries of Gα-gustducin and phospholipase C-β2 (PLCβ2), were identified in human gingival fibroblasts (HGFs). Various bitter agonists could induce an intensive cytosolic Ca²⁺ response in HGFs. More importantly, TAS2R16 was expressed at a relatively high level, and its agonist, salicin, showed robust Ca²⁺ evocative effects in HGFs. Activation of TAS2R16 signaling by salicin inhibited the release of lipopolysaccharide (LPS)-induced pro-inflammatory cytokines, at least in part, by repressing LPS-induced intracellular cAMP elevation and NF-κB p65 nuclear translocation in HGFs. These findings indicate that TAS2Rs activation in HGFs may mediate endogenous pro-inflammation resolution by antagonizing NF-κB signaling, providing a novel paradigm and treatment target for the better management of periodontitis.

Periodontal Disease: The Good, The Bad, and The Unknown

Periodontal disease is classically characterized by progressive destruction of the soft and hard tissues of the periodontal complex, mediated by an interplay between dysbiotic microbial communities and aberrant immune responses within gingival and periodontal tissues. Putative periodontal pathogens are enriched as the resident oral microbiota becomes dysbiotic and inflammatory responses evoke tissue destruction, thus inducing an unremitting positive feedback loop of proteolysis, inflammation, and enrichment for periodontal pathogens. Keystone microbial pathogens and sustained gingival inflammation are critical to periodontal disease progression. However, recent studies have revealed the importance of previously unidentified microbes involved in disease progression, including various viruses, phages and bacterial species. Moreover, newly identified immunological and genetic mechanisms, as well as environmental host factors, including diet and lifestyle, have been discerned in recent years as further contributory factors in periodontitis. These factors have collectively expanded the established narrative of periodontal disease progression. In line with this, new ideologies related to maintaining periodontal health and treating existing disease have been explored, such as the application of oral probiotics, to limit and attenuate disease progression. The role of systemic host pathologies, such as autoimmune disorders and diabetes, in periodontal disease pathogenesis has been well noted. Recent studies have additionally identified the reciprocated importance of periodontal disease in potentiating systemic disease states at distal sites, such as in Alzheimer's disease, inflammatory bowel diseases, and oral cancer, further highlighting the importance of the oral cavity in systemic health. Here we review long-standing knowledge of periodontal disease progression while integrating novel research concepts that have broadened our understanding of periodontal health and disease. Further, we delve into innovative hypotheses that may evolve to address significant gaps in the foundational knowledge of periodontal disease.

A lingering mouthwash with sustained antibiotic release and biofilm eradication for periodontitis

Dental plaque biofilms are believed to be one of the principal virulence factors in periodontitis resulting in tooth loss. Traditional mouthwashes are limited due to the continuous flow of saliva and poor drug penetration ability in the biofilm. Herein, we fabricated an antibiotic delivery platform based on natural polysaccharides (chitosan and cyclodextrin) as a novel mouthwash for the topical cavity delivery of minocycline. The penetration and residence mechanisms demonstrate that the platform can prolong the residence time up to 12 h on biofilms. Furthermore, sustained release can enhance the penetration of drugs into biofilms. In vitro antibiofilm experimental results indicated that the mouthwash effectively kills bacteria and eradicate biofilms. Effective treatment in vivo was confirmed by the significantly reduced dental plaque and alleviated inflammation observed in a rat periodontitis model. In summary, this novel platform can improve antibiofilm efficiency and prevent drugs from being washed away by saliva, which may provide benefits for many oral infectious diseases.

S100A8 and S100A9 in saliva, blood and gingival crevicular fluid for screening established periodontitis: a cross-sectional study

Background

Periodontitis is one of major oral diseases, which has no consensus on early screening tool. This study aimed to compare the association and screening ability of S100A8 and S100A9 in saliva, blood and gingival crevicular fluid (GCF) for periodontitis status.

Methods

We recruited 149 community Korean adults, 50 no or initial periodontitis (NIPERIO) and 99 established periodontitis (PERIO). Using clinical attachment loss and a panoramic radiograph, stage II–IV of new classification of periodontitis proposed at 2018 was considered cases as PERIO. Enzyme linked immunosorbent assay kit was used to quantify S100A8 and S100A9. T-test, analysis of covariance, Mann–Whitney test and correlation analysis were applied to compare the relationship of S100A8 and S100A9 in saliva, blood, and GCF for periodontitis. Receiver operating characteristic curve was applied for screening ability.

Results

Among S100A8 and S100A9 in saliva, blood and GCF, S100A8 in saliva was significantly higher in PERIO than in NIPERIO (p < 0.05). However, S100A8 and S100A9 in GCF were higher in NIPERIO (p < 0.05). The screening ability of salivary S100A8 was 75% for PERIO, while that of GCF S100A8 was 74% for NIPERIO. Salivary S100A8 was positively correlated to blood S100A8 (p < 0.05).

Conclusion

Salivary S100A8 could be a potential diagnostic marker for established periodontitis and be useful for screening established periodontitis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01749-z.

Periodontal status in children with primary immunodeficiencies

OBJECTIVE

This study aimed to assess associations between neutrophil-related primary immunodeficiencies (PIDs) and the presence of periodontal disease and other oral diseases and response to periodontal treatment.

BACKGROUND

Presence of neutrophil-related PIDs is thought to be a major risk factor for development of periodontitis.

METHODS

This study had both a cross-sectional and cohort design. Twenty-four children (age 4-16) with PIDs and 24 age-matched systemically healthy subjects received a dental clinical examination, including measures of probing pocket depths (PPD), clinical attachment loss (CAL) and bleeding on probing (BOP). Those found to be affected by periodontal disease were offered periodontal treatment and reassessed 6 months later.

RESULTS

Diagnosis of PIDs was associated with increased odds of presence of periodontal disease (p = .008 adjusted for age, gender, plaque, OR = 10.0, 95% CI = 1.83-54.38) and with continuous measures of periodontal disease such as number of PPDs >4 mm, mean PPD and mean CAL (all p < .001) and BOP (p = .001). However, only 7 out of 24 children were diagnosed with periodontitis. PIDs were also associated with a history of oral ulcers (p = .001, OR 12.47, 95% CI 2.71-57.29). An improvement in periodontal parameters (PPD and CAL) was detected following oral hygiene instructions and non-surgical periodontal therapy.

CONCLUSION

Although children affected by neutrophil-associated PIDs exhibited a higher prevalence of periodontal disease compared with systemically healthy children, severe periodontitis was rarely seen. This suggests that good systemic control of the PIDs may reduce their impact on the periodontium.

Galectin-3, Possible Role in Pathogenesis of Periodontal Diseases and Potential Therapeutic Target

Periodontal diseases are chronic inflammatory diseases that occur due to the imbalance between microbial communities in the oral cavity and the immune response of the host that lead to destruction of tooth supporting structures and finally to alveolar bone loss. Galectin-3 is a β-galactoside-binding lectin with important roles in numerous biological processes. By direct binding to microbes and modulation of their clearence, Galectin-3 can affect the composition of microbial community in the oral cavity. Galectin-3 also modulates the function of many immune cells in the gingiva and gingival sulcus and thus can affect immune homeostasis. Few clinical studies demonstrated increased expression of Galectin-3 in different forms of periodontal diseases. Therefore, the objective of this mini review is to discuss the possible effects of Galectin-3 on the process of immune homeostasis and the balance between oral microbial community and host response and to provide insights into the potential therapeutic targeting of Gal-3 in periodontal disease.

Application of specialized pro-resolving mediators in periodontitis and peri-implantitis: a review

Scaling and root planning is a key element in the mechanical therapy used for the eradication of biofilm, which is the major etiological factor for periodontitis and peri‐implantitis. However, periodontitis is also a host mediated disease, therefore, removal of the biofilm without adjunctive therapy may not achieve the desired clinical outcome due to persistent activation of the innate and adaptive immune cells. Most recently, even the resident cells of the periodontium, including periodontal ligament fibroblasts, have been shown to produce several inflammatory factors in response to bacterial challenge. With increased understanding of the pathophysiology of periodontitis, more research is focusing on opposing excessive inflammation with specialized pro‐resolving mediators (SPMs). This review article covers the major limitations of current standards of care for periodontitis and peri‐implantitis, and it highlights recent advances and prospects of SPMs in the context of tissue reconstruction and regeneration. Here, we focus primarily on the role of SPMs in restoring tissue homeostasis after periodontal infection.

Association of bacterial vaginosis with periodontitis in a cross-sectional American nationwide survey

To explore the association between bacterial vaginosis (BV) and periodontitis (PD) and to determine whether PD and BV might be linked with systemic serum alterations. We used the National Health and Nutrition Examination Survey 2001-2004, with women aged 18-49 years old and diagnosed with or without BV according to Nugent's method. PD was defined according to the 2012 case definition. We compared serum counts according to the presence of PD and the presence of BV. Multivariable regression was used to explore and identify relevant variables towards the presence of BV. 961 women fulfilled the inclusion criteria. In women with BV, PD was associated with higher inflammation, characterized by increased white blood cells (p = 0.006) and lymphocyte (p = 0.009) counts. Predictive models presented a statistically significant association between PD and BV [Odds Ratio (OD) = 1.69, 95% Confidence Interval (CI): 1.09-2.61 for periodontitis; OD = 2.37, 95% CI: 1.30-4.29 for severe PD]. Fully adjusted models for age, smoking, body mass index, diabetes mellitus and number of systemic conditions reinforced this association [OD = 1.71, 95% CI: 1.06-2.76 for PD; OD = 2.21, 95% CI: 1.15-4.25 for severe PD]. An association between BV and PD is conceivable. PD was associated with higher systemic markers of inflammation in women with BV. Our data is novel and could serve as a foundation to guide future studies in the confirmation of this association and the underlying mechanisms.

The Role of the Immune Microenvironment in Bone Regeneration

Bone is an active tissue, being constantly renewed in healthy individuals with participation of the immune system to a large extent. Any imbalance between the processes of bone formation and bone resorption is linked to various inflammatory bone diseases. The immune system plays an important role in tissue formation and bone resorption. Recently, many studies have demonstrated complex interactions between the immune and skeletal systems. Both of immune cells and cytokines contribute to the regulation of bone homeostasis, and bone cells, including osteoblasts, osteoclasts, osteocytes, also influence the cellular functions of immune cells. These crosstalk mechanisms between the bone and immune system finally emerged, forming a new field of research called osteoimmunology. Therefore, the immune microenvironment is crucial in determining the speed and outcome of bone healing, repair, and regeneration. In this review, we summarise the role of the immune microenvironment in bone regeneration from the aspects of immune cells and immune cytokines. The elucidation of immune mechanisms involved in the process of bone regeneration would provide new therapeutic targets for improving the curative effects of bone injury treatment.

Neutrophils exhibit an individual response to different oral bacterial biofilms

Oral innate immunity is led by neutrophils. It is still unclear how their main antimicrobial mechanisms against different biofilms may contribute to balance or dysregulation in the oral cavity. We investigated the capacity of commensal (Streptococcus oralis) and pathogenic (Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans) monospecies biofilms to induce or to inhibit selected antimicrobial mechanisms of neutrophils. S. oralis induced neutrophil extracellular traps (NETs) formation, reactive oxygen species (ROS) production, and matrix metalloproteinases (MMPs) 8 and 9 secretion. However, these responses were partially reduced in PMA-activated neutrophils indicating a balance-like neutrophil response, which might be important for the maintenance of oral health. P. gingivalis generally induced ROS. Reduced NET formation and significantly decreased MMP secretion were detectable in activated neutrophils highlighting P. gingivalis’ nucleolytic and proteolytic activity, which might support bacterial colonization and pathogenesis of periodontitis. In contrast, A. actinomycetemcomitans did not affect the levels of antimicrobial factors in activated neutrophils and induced NET formation, ROS production, and secretion of MMP-8 and -9 in neutrophils alone, which might contribute to tissue destruction and disease progression. In summary, neutrophil responses to biofilms were species-specific and might support either maintenance of oral health or pathogenesis of periodontitis depending on the species.

Evaluation of periodontal status and cytokine/chemokine profile of GCF in patients with severe congenital neutropenia

Severe congenital neutropenia (SCN) is a primary immunodeficiency characterized by defect in neutrophil count. Increased risk of infections in addition to periodontal problems, such as ulcerations of oral mucosa, gingival inflammation, and rapid loss of attachment are common in the course of the disease. The aim of the present study is to define the causal relationship between the severity of periodontal inflammation and severe congenital neutropenia through identification of cytokine profile in gingival crevicular fluid (GCF). A case-control study was performed in patients diagnosed with SCN and healthy controls. Demographic data, the molecular defect, laboratory work-up were gathered from the hospital registry. Periodontal indices were recorded and GCF samples were analyzed using multiplex analysis for the simultaneous measurements of the particular cytokines and chemokines. The present study included 14 patients and 22 control subjects. Both groups were comparable in terms of age and sex. Severity of gingival inflammation measured by the criteria of Löe was higher in the SCN cases (p < 0.05). Moreover, GCF levels of IFN-α, TNF-α, IL-10, IL-13, IL-15, IL-17, IL-2, IL-7, IL-33, IP-10, MIG, MIP-1β were significantly higher in the controls. Decreased cytokine secretion seems to correlate with the decrease in neutrophil counts. The severity of gingival inflammation in SCN patients may be due to the bacterial overgrowth and the change in the content of the oral flora due to the decreased neutrophil counts. Therefore, regular periodontal examinations, the motivation of oral hygiene as well as the compliance with therapy in SCN patients contribute to the periodontal health.

Cytomorphometric Analysis of Inflammation Dynamics in the Periodontium Following the Use of Fixed Dental Prostheses

Cytomorphometry is used in the sampling of biological materials and diagnostic procedures. The use of cytological studies in periodontal diseases is not well described in the literature. Our study aimed to quantitatively assess the inflammation dynamics using cytomorphometric analysis of the periodontium before and after the use of fixed dental prostheses. Following ethics approval, a total of 105 subjects were divided in 3 groups as gingivitis (n = 23), periodontitis (n = 58), and healthy periodontium (control) (n = 24). The fixed dental prostheses (crowns and fixed partial dentures) were fabricated from cobalt-chrome metal-ceramic prostheses using the conventional method (C/M-CoCr), cobalt-chrome metal-ceramic prostheses by the computer-aided design and computer-aided manufacturing (CAD/CAM) technique (C/C-CoCr), and zirconia-based ceramic prostheses by the CAD/CAM technique (C/C-Zr) among subjects with gingivitis and periodontitis. The gingival crevicular fluid (GCF) was obtained from subjects before and after the use of the prostheses. The total count of epithelial cells and the connective tissue cells or polymorphonuclear neutrophils (PMNs) in GCF were studied using cytomorphometric analysis. The Statistical Package Tor the Social Sciences (SPSS), Version 20 (IBM Company, Chicago, IL, USA) was used to analyze the results and the significance level was set at p = 0.05. The data for before and after the use of the prostheses were compared using independent t-Tests. Similarly, the results after the use of prostheses in gingivitis, periodontitis, and control in each type of prostheses were compared using One-way ANOVA with post hoc using Scheffe. The total epithelial cells and the PMNs were determined along with the epithelium/leukocyte index. Regardless of the prostheses type used, no significant change in the parameters was identified among patients with a healthy periodontium, before and after prosthetic treatment. In all study groups, a statistically increase (p value < 0.05) was observed in the oral epithelial cell counts and a statistically decrease (p < 0.05) in the PMNs count following the use of the fixed prostheses. Data on cytomorphometric analysis could enable the selection of the most appropriate prostheses for use in patients with periodontal pathologies. When choosing prostheses, changes in the composition of GCF could be considered as a useful criterion for their use.

Local promotion of B10 function alleviates experimental periodontitis bone loss through antagonizing RANKL-expressing neutrophils

BACKGROUND

Persistent host immune responses initiated by oral bacteria protect host against infection but may also elicit the process of sustained periodontal inflammation and subsequent alveolar bone loss. Interleukin-10 (IL-10), an anti-inflammatory cytokine, can downregulate pro-inflammatory cytokine and inhibit neutrophil migration in inflammation. IL-10-expressing regulatory B cells (B10) is termed by negatively regulating immune response through IL-10 and are mainly restricted in CD19⁺ CD1d^hi CD5⁺ B cells in mice. Our current study was aimed to explore the effect of locally transferred CD19⁺ CD1d^hi CD5⁺ B cells on inflammation and alveolar bone loss in an experimental periodontitis mouse model.

METHODS

Ligation plus P. gingivalis (Pg) infection was used to induce periodontitis in a mouse model. CD19⁺ CD1d^hi CD5⁺ B cells were sorted by flow cytometry and transferred into the gingivae immediately on the fifth day after ligation. All the mice were sacrificed on day 14 after ligation.

RESULTS

H&E staining showed that inflammatory cell infiltration was significantly reduced by the CD19⁺ CD1d^hi CD5⁺ B cells. Toluidine blue staining showed that the CD19⁺ CD1d^hi CD5⁺ B cells alleviated alveolar bone loss in the ligature/Pg-induced periodontitis in mice. Immunohistochemical staining showed Receptor Activator of NF-KappaB Ligand (RANKL), Interleukin-1β(IL-1β) and Interleukin-17 (IL-17) were decreased after the CD19⁺ CD1d^hi CD5⁺ B cell transfer. Immunofluorescent staining showed that IL-10 was increased while the number of Ly6G⁺ neutrophil and its RANKL production were decreased in gingival tissue.

CONCLUSIONS

These results indicated that locally transferred CD19⁺ CD1d^hi CD5⁺ B cells may alleviate alveolar bone loss through inhibiting pro-inflammatory cytokine expression and RANKL-expressing neutrophils in the periodontitis mouse model.

The role of inflammation and genetics in periodontal disease

Periodontitis is a complex disease: (a) various causative factors play a role simultaneously and interact with each other; and (b) the disease is episodic in nature, and bursts of disease activity can be recognized, ie, the disease develops and cycles in a nonlinear fashion. We recognize that various causative factors determine the immune blueprint and, consequently, the immune fitness of a subject. Normally, the host lives in a state of homeostasis or symbiosis with the oral microbiome; however, disturbances in homeostatic balance can occur, because of an aberrant host response (inherited and/or acquired during life). This imbalance results from hyper- or hyporesponsiveness and/or lack of sufficient resolution of inflammation, which in turn is responsible for much of the disease destruction seen in periodontitis. The control of this destruction by anti-inflammatory processes and proresolution processes limits the destruction to the tissues surrounding the teeth. The local inflammatory processes can also become systemic, which in turn affect organs such as the heart. Gingival inflammation also elicits changes in the ecology of the subgingival environment providing optimal conditions for the outgrowth of gram-negative, anaerobic species, which become pathobionts and can propagate periodontal inflammation and can further negatively impact immune fitness. The factors that determine immune fitness are often the same factors that determine the response to the resident biofilm, and are clustered as follows: (a) genetic and epigenetic factors; (b) lifestyle factors, such as smoking, diet, and psychosocial conditions; (c) comorbidities, such as diabetes; and (d) local and dental factors, as well as randomly determined factors (stochasticity). Of critical importance are the pathobionts in a dysbiotic biofilm that drive the viscious cycle. Focusing on genetic factors, currently variants in at least 65 genes have been suggested as being associated with periodontitis based on genome-wide association studies and candidate gene case control studies. These studies have found pleiotropy between periodontitis and cardiovascular diseases. Most of these studies point to potential pathways in the pathogenesis of periodontal disease. Also, most contribute to a small portion of the total risk profile of periodontitis, often limited to specific racial and ethnic groups. To date, 4 genetic loci are shared between atherosclerotic cardiovascular diseases and periodontitis, ie, CDKN2B-AS1(ANRIL), a conserved noncoding element within CAMTA1 upstream of VAMP3, PLG, and a haplotype block at the VAMP8 locus. The shared genes suggest that periodontitis is not causally related to atherosclerotic diseases, but rather both conditions are sequelae of similar (the same?) aberrant inflammatory pathways. In addition to variations in genomic sequences, epigenetic modifications of DNA can affect the genetic blueprint of the host responses. This emerging field will yield new valuable information about susceptibility to periodontitis and subsequent persisting inflammatory reactions in periodontitis. Further studies are required to verify and expand our knowledge base before final cause and effect conclusions about the role of inflammation and genetic factors in periodontitis can be made.

The role of the microbiota in periodontal disease

The last decade has witnessed unparalleled advances in our understanding of the complexity of the oral microbiome and the compositional changes that occur in subgingival biofilms in the transition from health to gingivitis and to destructive periodontal disease. The traditional view, which has held sway for the last 2 decades, that disease is characterized by the outgrowth of a consortium, or consortia, of a limited number of potentially pathogenic organisms, has given way to an alternative paradigm. In this new view, the microbiological changes associated with disease represent whole-scale alterations to the overall microbial population structure and to the functional properties of the entire community. Thus, and in common with other microbially mediated diseases of the gastrointestinal tract, the normally balanced, symbiotic, and generally benign commensal microbiome of the tooth-associated biofilm undergoes dysbiosis to a potentially deleterious microbiota. Coincident with progress in defining the microbiology of these diseases, there have been equally important advances in our understanding of the inflammatory systems of the periodontal tissues, their control, and how inflammation may contribute both to the development of dysbiosis and, in a deregulated state, the destructive disease process. One can therefore speculate that the inflammatory response and the periodontal microbiome are in a bidirectional balance in oral health and a bidirectional imbalance in periodontitis. However, despite these clear insights into both sides of the host/microbe balance in periodontal disease, there remain several unresolved issues concerning the role of the microbiota in disease. These include, but are not limited to, the factors which determine progression from gingivitis to periodontitis in a proportion of the population, whether dysbiosis causes disease or results from disease, and the molecular details of the microbial stimulus responsible for driving the destructive inflammatory response. Further progress in resolving these issues may provide significant benefit to diagnosis, treatment, and prevention.

Chemokines and cytokines profile in whole saliva of patients with periodontitis

Clinical features suggest differences in immune response among periodontitis forms, albeit a large number of cytokines and chemokines remain to be evaluated. The saliva is an available source of mediators and its analysis would be valuable in order to understand pathophysiological differences. The objective of this study was analyze chemokines/cytokines profile in whole saliva of individuals with severe periodontitis (Stage III) presenting moderate [Grade B; GB] or rapid progression rate with a localized incisor-molar pattern [Grade C; GC/IMP]. A case-control study was designed for each periodontitis group. GB (n = 9) and GC/IMP (n = 7) patients and their healthy controls (C-GB, n = 9 and C-GC, n = 7) were evaluated. Non-stimulated saliva samples were assessed by a multiplex assay for a total of 40 cytokines, C-C and C-X-C motif chemokines. GC/IMP group presented higher levels of CCL17 and CCL27 (p = 0.04, FDR > 0.05), and lower levels of CCL2 (p = 0.04, FDR > 0.05) and CCL25 (p = 0.006, FDR < 0.05) when compared to its control. GB patients had higher levels of IL-6, IL-1β (p = 0.04, FDR > 0.05), and elevated pro-inflammatory (TNF-α,IL-1β,INF-γ,IL-6, IL-16): anti-inflammatory (IL-2, IL-4, IL-10) ratio (p = 0.01, FDR < 0.05) compared to its control [p-values by Mann-Whitney test, and False Discovery Rate (FDR) by Benjamini-Hochburg corrections]. CCL-chemokines and cytokines contributed to differences between GC/C-GC and GB/C-GB, respectively (p < 0.05, PERMANOVA test). These preliminary data revealed that each periodontitis phenotype presented distinct immune profiles differentially expressed in saliva compared to their related controls, suggesting differences in the etiopathogenesis of GB and GC/IMP.

Platelet-Rich Fibrin Can Neutralize Hydrogen Peroxide-Induced Cell Death in Gingival Fibroblasts

Hydrogen peroxide is a damage signal at sites of chronic inflammation. The question arises whether platelet-rich fibrin (PRF), platelet-poor plasma (PPP), and the buffy coat can neutralize hydrogen peroxide toxicity and thereby counteract local oxidative stress. In the present study, gingival fibroblasts cells were exposed to hydrogen peroxide with and without lysates obtained from PRF membranes, PPP, heated PPP (75 °C for 10 min), and the buffy coat. Cell viability was examined by trypan blue staining, live-dead staining, and formazan crystal formation. Cell apoptosis was assessed by cleaved caspase-3 Western blot analysis. Reverse transcription-quantitative polymerase chain reaction (RT-PCR) was utilized to determine the impact of PRF lysates on the expression of catalase in fibroblasts. It was reported that lysates from PRF, PPP, and the buffy coat—but not heated PPP—abolished the hydrogen peroxide-induced toxicity in gingival fibroblasts. Necrosis was confirmed by a loss of membrane integrity and apoptosis was ruled out by the lack of cleavage of caspase-3. Aminotriazole, an inhibitor of catalase, reduced the cytoprotective activity of PRF lysates yet blocking of glutathione peroxidase by mercaptosuccinate did not show the same effect. PRF lysates had no impact on the expression of catalase in gingival fibroblasts. These findings suggest that PRF, PPP, and the buffy coat can neutralize hydrogen peroxide through the release of heat-sensitive catalase.

Effect of non-surgical periodontal treatment on gingival crevicular fluid hypoxia inducible factor-1 alpha, vascular endothelial growth factor and tumor necrosis factor-alpha levels in generalized aggressive periodontitis patients

BACKGROUND

Hypoxia-inducible angiogenic pathway involving hypoxia inducible factor-1 alpha (HIF-1α), vascular endothelial growth factor (VEGF) and tumor necrosis factor-alpha (TNF-α) may regulate several biological processes related to inflammation. The present study aimed to assess the effect of non-surgical periodontal treatment on gingival crevicular fluid (GCF) HIF-1α, VEGF, and TNF-α levels in generalized aggressive periodontitis (G-AgP).

METHODS

Twenty G-AgP patients and 20 periodontally healthy individuals were included. G-AgP patients received scaling and root planning (SRP), per quadrant at a 1-week-interval, performed with ultrasonic and periodontal hand instruments. GCF samples were collected and clinical periodontal parameters including probing depth, clinical attachment level, gingival index and plaque index were recorded at baseline, 1 and 3 months after treatment. Biomarker levels in GCF were analyzed by ELISA.

RESULTS

At baseline all clinical parameters and GCF HIF-1α, VEGF, and TNF-α levels were significantly higher in G-AgP patients compared to healthy control (P < 0.05). All clinical parameters improved over the 3-month-period in G-AgP patients (P < 0.05). GCF HIF-1α levels in G-AgP reduced at 1 and 3 months post-treatment, however, this did not reach to statistical significance (P > 0.05). GCF VEGF and TNF-α levels remained unchanged throughout the study period (P > 0.05).

CONCLUSIONS

Within the limitations of the present study, although HIF-1α seems to possess a potential diagnostic value for G-AgP, it might not be a proper predictor of clinically favorable treatment outcome. SRP plus different adjunctive therapies could provide better information about the prognostic role of hypoxia-inducible angiogenic pathway in G-AgP.

Sudachitin Inhibits Matrix Metalloproteinase-1 and -3 Production in Tumor Necrosis Factor-α-Stimulated Human Periodontal Ligament Cells

Sudachitin, a polymethoxylated flavonoid found in the skin of Citrus sudachi, is a biologically active substance. The aim of this study was to examine whether sudachitin could be used to inhibit the expression of matrix metalloproteinase (MMP)-1 and MMP-3, which are involved in the destruction of periodontal tissues in periodontal lesions, in tumor necrosis factor (TNF)-α-stimulated human periodontal ligament cells (HPDLC). Sudachitin suppressed TNF-α-induced MMP-1 and MMP-3 production in HPDLC. On the other hand, it enhanced tissue inhibitor of metalloproteinase (TIMP)-1 expression. The level of Akt phosphorylation in the TNF-α-stimulated HPDLC was decreased by sudachitin treatment. Moreover, an Akt inhibitor reduced MMP-1 and MMP-3 production and increased TIMP-1 production. These findings indicate that sudachitin reduces MMP-1 and MMP-3 production in TNF-α-stimulated HPDLC by inhibiting the Akt pathway.

Unique etiologic, demographic, and pathologic characteristics of localized aggressive periodontitis support classification as a distinct subcategory of periodontitis

BACKGROUND

Localized aggressive periodontitis (LAgP) occurs in 2% of African-American adolescents but only 0.15% of white adolescents. First molars and incisors are affected by rapid onset and progression.

METHODS

This nonsystematic critical review evaluated published data for LAgP and chronic periodontitis (CP), focusing on potential differences in epidemiology, microbiology, immunology, genetics, and response to therapy.

RESULTS

LAgP differs from CP by localization to incisors and first molars, early onset and rapid progression in adolescents and young adults, and a 10-fold higher prevalence in populations of African or Middle Eastern origin, often with strong familial aggregation. The bacterium Aggregatibacter actinomycetemcomitans and hyperresponsive neutrophils are frequently observed. Antibiotic and nonsurgical therapies are highly effective.

CONCLUSIONS

LAgP differs in many ways from the far more common CP that affects older adults. The substantial evidence of dissimilarities summarized in this review strongly supports the classification of LAgP as a distinct form of periodontitis.

PRACTICAL IMPLICATIONS

Classifying LAgP as a distinct subcategory of periodontitis will encourage future research and does not conflict with the newly proposed "staging and grading" system. The silent onset and rapid progression of LAgP make early diagnosis and frequent follow-up with patients essential for effective treatment.

Biochemical parameters and oxidative stress markers in Tunisian patients with periodontal disease

BACKGROUND

Oxidative stress is involved in many diseases including diabetes and cancer. Numbers of studies have suggested its involvement in the pathogenesis of periodontal diseases. The aim of this study was to evaluate the levels of biochemical parameters and oxidative stress markers in plasma of healthy and chronic periodontitis patients.

METHODS

One hundred thirty subjects were divided into two groups; patients (mean age = 42 ± 13.6 y.o) and control (mean age = 44.8 ± 12.6 y.o). Patients and healthy subjects were free from any infection, coronary or heart disease, diabetes or liver failure. Total cholesterol, LDLc, HDLc, Triglycerides (TG), creatinine, uric acid (UA), glucose and urea levels as well as the activities of enzymatic antioxidants such as catalase, glutathione reductase (GR) and total antioxidant capacity (TAOC), were measured in plasma samples using colorimetric assays. Statistical differences between groups were determined by Student's t-test and p ≤ 0.05 was considered as significant.

RESULTS

Periodontitis patients exhibited significant decrease in the activities of catalase, TAOC, GR and TG, cholesterol, LDLc, glucose, HDLc, uric acid levels in plasma samples in comparison with healthy subjects. However, no statistically significant differences in the levels of creatinine and urea were observed between the two groups.

CONCLUSION

The reduction of plasma antioxidant activities (Catalase, TAOC, GR) may have a role in the pathogenesis of periodontal diseases. Our findings suggest a decrease in the host capacity to control the damage caused by oxidative stress. Therefore, therapeutic strategies, aiming at modulating the oxidative stress could be considered as potential tools for the prevention or treatment of periodontal diseases and their potential systemic effects on the general health.

Periodontal status of children with primary immunodeficiencies: a systematic review

OBJECTIVE

The aim of this systematic review was to appraise the existing literature on periodontal disease in children affected by different types of neutrophil-associated primary immunodeficiencies (PIDs).

METHODS

A PRESS-validated search strategy was developed to search through databases MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, LILACS, Google Scholar and Open Grey. All included studies were assessed for methodological quality and risk of bias.

RESULTS

One hundred eighteen articles reporting on 160 PID patients were included for qualitative analysis. The majority (70%) were individual case reports. Clinical and radiographic manifestations of the periodontal disease included poor oral hygiene, generalised alveolar bone loss, severe gingival inflammation, increased pocket depths, tooth mobility and gingival recession. For most studies, the primary intervention was periodontal treatment in the form of scaling and root planing or dental extractions. Stabilisation of the periodontal condition varied between different PIDs. In severe congenital neutropenia (SCN), 61% of cases reported stabilisation of the periodontal condition, while for all other PIDs, 'stability' was reported in less than 43% of cases.

CONCLUSION

The published literature suggests that patients with PIDs can present with severe periodontitis and that conventional treatment approaches have limited benefits.

A dysbiotic microbiome triggers TH17 cells to mediate oral mucosal immunopathology in mice and humans

Periodontitis is one of the most common human inflammatory diseases, yet the mechanisms that drive immunopathology and could be therapeutically targeted are not well defined. Here, we demonstrate an expansion of resident memory T helper 17 (T_H17) cells in human periodontitis. Phenocopying humans, T_H17 cells expanded in murine experimental periodontitis through local proliferation. Unlike homeostatic oral T_H17 cells, which accumulate in a commensal-independent and interleukin-6 (IL-6)-dependent manner, periodontitis-associated expansion of T_H17 cells was dependent on the local dysbiotic microbiome and required both IL-6 and IL-23. T_H17 cells and associated neutrophil accumulation were necessary for inflammatory tissue destruction in experimental periodontitis. Genetic or pharmacological inhibition of T_H17 cell differentiation conferred protection from immunopathology. Studies in a unique patient population with a genetic defect in T_H17 cell differentiation established human relevance for our murine experimental studies. In the oral cavity, human T_H17 cell defects were associated with diminished periodontal inflammation and bone loss, despite increased prevalence of recurrent oral fungal infections. Our study highlights distinct functions of T_H17 cells in oral immunity and inflammation and paves the way to a new targeted therapeutic approach for the treatment of periodontitis.

Osteoimmunology of Oral and Maxillofacial Diseases: Translational Applications Based on Biological Mechanisms

The maxillofacial skeleton is highly dynamic and requires a constant equilibrium between the bone resorption and bone formation. The field of osteoimmunology explores the interactions between bone metabolism and the immune response, providing a context to study the complex cellular and molecular networks involved in oro-maxillofacial osteolytic diseases. In this review, we present a framework for understanding the potential mechanisms underlying the immuno-pathobiology in etiologically-diverse diseases that affect the oral and maxillofacial region and share bone destruction as their common clinical outcome. These otherwise different pathologies share similar inflammatory pathways mediated by central cellular players, such as macrophages, T and B cells, that promote the differentiation and activation of osteoclasts, ineffective or insufficient bone apposition by osteoblasts, and the continuous production of osteoclastogenic signals by immune and local stromal cells. We also present the potential translational applications of this knowledge based on the biological mechanisms involved in the inflammation-induced bone destruction. Such applications can be the development of immune-based therapies that promote bone healing/regeneration, the identification of host-derived inflammatory/collagenolytic biomarkers as diagnostics tools, the assessment of links between oral and systemic diseases; and the characterization of genetic polymorphisms in immune or bone-related genes that will help diagnosis of susceptible individuals.

Aggregatibacter actinomycetemcomitans (Aa) Under the Radar: Myths and Misunderstandings of Aa and Its Role in Aggressive Periodontitis

Aggregatibacter actinomycetemcomitans (Aa) is a low-abundance Gram-negative oral pathobiont that is highly associated with a silent but aggressive orphan disease that results in periodontitis and tooth loss in adolescents of African heritage. For the most part Aa conducts its business by utilizing strategies allowing it to conceal itself below the radar of the host mucosal immune defense system. A great deal of misinformation has been conveyed with respect to Aa biology in health and disease. The purpose of this review is to present misconceptions about Aa and the strategies that it uses to colonize, survive, and evade the host. In the process Aa manages to undermine host mucosal defenses and contribute to disease initiation. This review will present clinical observational, molecular, and interventional studies that illustrate genetic, phenotypic, and biogeographical tactics that have been recently clarified and demonstrate how Aa survives and suppresses host mucosal defenses to take part in disease pathogenesis. At one point in time Aa was considered to be the causative agent of Localized Aggressive Periodontitis. Currently, it is most accurate to look at Aa as a community activist and necessary partner of a pathogenic consortium that suppresses the initial host response so as to encourage overgrowth of its partners. The data for Aa's activist role stems from molecular genetic studies complemented by experimental animal investigations that demonstrate how Aa establishes a habitat (housing), nutritional sustenance in that habitat (food), and biogeographical mobilization and/or relocation from its initial habitat (transportation). In this manner Aa can transfer to a protected but vulnerable domain (pocket or sulcus) where its community activism is most useful. Aa's “strategy” includes obtaining housing, food, and transportation at no cost to its partners challenging the economic theory that “there ain't no such thing as a free lunch.” This “strategy” illustrates how co-evolution can promote Aa's survival, on one hand, and overgrowth of community members, on the other, which can result in local host dysbiosis and susceptibility to infection.

Periodontal ligament-derived mesenchymal stem cells modulate neutrophil responses via paracrine mechanisms

BACKGROUND

Mesenchymal stem cells differentiate into distinct mesenchymal cell lineages and regulate the immune response. The aim of this study was to determine whether periodontal ligament-derived mesenchymal stem cells (PDLSCs) have the ability to modulate neutrophil responses via paracrine mechanisms.

METHODS

CD105-enriched PDLSCs were seeded for 24 h and challenged with Porphyromonas gingivalis total protein extract (PgPE) (0 or 2 ug/mL) for 3 h. Cells were then washed and further cultured for 18 h and the supernatants were collected and stored. Next, neutrophil-differentiated human promyelocytic leukemia HL-60 cells (HL60D) were treated with PDLSCs supernatants and HL-60D activation and functional responses were determined.

RESULTS

PgPE treatment induced higher secretion of inflammatory markers and chemokines by PDLSCs, including RANTES, eotaxin, interferon (IFN)-γ- inducible protein 10 (IP-10), monocyte chemoattractant protein-1 (MCP-1), IFN-γ, interleukin (IL)-6, IL-8 and IL-1ra (P < 0.05). HL-60D recruitment rate was increased by 4.7 ± 1.09-fold when exposed to PgPE-treated PDLSCs supernatants. PgPE-treated PDLSCs supernatants promoted a 1.78 ± 1.04-fold increase in the production of intracellular reactive oxygen species (ROS) by PMA-stimulated HL-60D, whereas PgPE-untreated PDLSCs supernatants led to a 16% reduction in intracellular ROS. In sharp contrast, neither PgPE-untreated nor PgPE-treated PDLSCs supernatants altered tumor necrosis factor (TNF)-α and IL-1β secretion by HL-60D cells.

CONCLUSION

Together, these findings suggest an important role of PDLSCs in the recognition of P. gingivalis, paracrine recruitment and activation of antimicrobial mechanisms in innate immune cells, without interfering in cytokine responses.

Diacylglycerol Kinase Malfunction in Human Disease and the Search for Specific Inhibitors

The diacylglycerol kinases (DGKs) are master regulator kinases that control the switch from diacylglycerol (DAG) to phosphatidic acid (PA), two lipids with important structural and signaling properties. Mammalian DGKs distribute into five subfamilies that regulate local availability of DAG and PA pools in a tissue- and subcellular-restricted manner. Pharmacological manipulation of DGK activity holds great promise, given the critical contribution of specific DGK subtypes to the control of membrane structure, signaling complexes, and cell-cell communication. The latest advances in the DGK field have unveiled the differential contribution of selected isoforms to human disease. Defects in the expression/activity of individual DGK isoforms contribute substantially to cognitive impairment, mental disorders, insulin resistance, and vascular pathologies. Abnormal DGK overexpression, on the other hand, confers the acquisition of malignant traits including invasion, chemotherapy resistance, and inhibition of immune attack on tumors. Translation of these findings into therapeutic approaches will require development of methods to pharmacologically modulate DGK functions. In particular, inhibitors that target the DGKα isoform hold particular promise in the fight against cancer, on their own or in combination with immune-targeting therapies.

Resveratrol attenuates oxidative stress during experimental periodontitis in rats exposed to cigarette smoke inhalation

OBJECTIVES

This study aimed at investigating the effect of the systemic administration of resveratrol (RESV) on oxidative stress during experimental periodontitis in rats subjected to cigarette smoke inhalation.

MATERIAL AND METHODS

Experimental periodontitis (EP) was induced in 26 male Wistar rats by the insertion of a ligature around one of the first mandibular and maxillary molars. The animals were assigned randomly to the following groups: cigarette smoke inhalation (CSI; 3 times/d, 8 minutes/d) + resveratrol (10 mg/Kg), that is, SMK + RESV (n = 13) and cigarette smoke inhalation + placebo, that is, SMK + PLAC (n = 13). The substances were administered daily for 30 days (19 days prior and 11 days following EP induction), and then, the animals were euthanized. The maxillary specimens were processed for morphometric analysis of bone loss, and the tissue surrounding the first maxillary molars was collected for mRNA quantification of Sirtuin 1 (SIRT1) by real-time PCR. The gingival tissues surrounding the mandibular first molars were collected for quantification of superoxide dismutase 1 (SOD1) and nicotinamide adenine dinucleotide phosphatase oxidase (NADPH) using an ELISA assay.

RESULTS

Reduced bone loss was demonstrated in animals in the SMK + RESV group as compared to those in the SMK + PLAC (P < 0.05) group on the basis of morphometric analysis. Resveratrol promoted higher levels of SIRT and SOD (P < 0.05) as well as reduced levels of NADPH oxidase (P < 0.05) were found in tissues derived from animals in the SMK + RESV group when compared to those in the SMK + PLAC group.

CONCLUSION

Resveratrol is an efficient therapeutic agent that reduces exacerbation of bone loss found in animals with EP that were also exposed to smoke. The results suggest that its effects could be mediated, at least in part, by its antioxidant and anti-inflammatory properties which attenuate the effects of oxidative stress on EP in the presence of cigarette smoke.

A novel pH-responsive quaternary ammonium chitosan-liposome nanoparticles for periodontal treatment

The aim of this study was to evaluate the antibacterial activity and cytocompatibility of novel pH-activated nanoparticles (NPs) in vitro and in vivo. The NPs were synthesized from a quaternary ammonium chitosan, i.e., N,N,N-trimethyl chitosan, a liposome, and doxycycline (TMC-Lip-DOX NPs). The cytocompatibility of the NPs was evaluated. The TMC-Lip-DOX NPs achieved superb inhibition of free mixed bacteria and biofilm formation. They also showed excellent biocompatibility with human periodontal ligament fibroblasts. Animal experiments showed that the NPs strongly inhibited biofilm formation and prevented alveolar bone absorption in vivo. All the results indicate that the TMC-Lip-DOX NPs have good potential for use in the treatment of periodontal and other inflammatory diseases.

Analysis of metabolic profiles of generalized aggressive periodontitis

BACKGROUND AND OBJECTIVE

The specific pathogenesis of generalized aggressive periodontitis (GAgP) has not yet been clarified, and few studies have focused on the association between GAgP and metabolomics. To elucidate the roles of metabolic profiles in the status of GAgP, this study aimed to identify the differential metabolic profiles between patients with GAgP and healthy controls using an untargeted metabolomic profiling method.

MATERIAL AND METHODS

Serum and gingival crevicular fluid samples were collected from healthy controls (n = 20) and patients with GAgP (n = 20) in this cross-sectional study. The relative levels of biomarkers in the samples were measured by gas chromatography-mass spectrometry. Principal components analysis and orthogonal partial least-squares discriminant analysis were used for statistical analysis. Metabolites were analysed qualitatively using the FiehnLib and NIST databases. Full-mouth probing depth and clinical attachment loss were recorded as indexes of periodontal disease.

RESULTS

A total of 349 metabolites were qualitatively detected in the gingival crevicular fluid samples, and 200 metabolites were detected in the serum samples. Compared with healthy controls, patients with GAgP showed significant increases in serum urea and allo-inositol levels. In contrast, glutathione, 2,5-dihydroxybenzaldehyde, adipic acid and 2-deoxyguanosine levels were decreased in patients with GAgP. In the gingival crevicular fluid samples, noradrenaline, uridine, α-tocopherol, dehydroascorbic acid, xanthine, galactose, glucose-1-phosphate and ribulose-5-phosphate levels were increased in patients with GAgP, while thymidine, glutathione and ribose-5-phosphate levels were decreased.

CONCLUSION

The metabolomics analysis by gas chromatography-mass spectrometry is an effective and minimally non-invasive way to differentiate the metabolites characteristic of patients with GAgP. Both serum and gingival crevicular fluid metabolomics are significantly different between patients with GAgP and healthy controls. These metabolic profiles have great potential in detecting GAgP and helping to understand its underlying mechanisms.

The effect of dietary corn oil and fish oil supplementation in dogs with naturally occurring gingivitis

The aim of this randomized, double-blinded, placebo-controlled study was to evaluate if downregulation of the inflammatory response due to ingestion of high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can slow down gingivitis development, and thus delay the progression of periodontal disease (PD) in dogs. To this aim, 44 client-owned adult dogs (>1 and <8 years old) with naturally occurring PD (stages 1 and 2) were submitted to a plaque, gingivitis and calculus scoring followed by a dental cleaning procedure and collection of blood samples. The animals were then fed a canine adult maintenance diet, supplemented with either corn oil (0.00 g EPA and 0.00 g DHA) or fish oil (1.53 g EPA and 0.86 g DHA, both per 1,000 kcal ME) over the following 5 months. At the end of this period, the PD scoring and the blood sampling were repeated. The animals consuming fish oil had higher plasma levels of the longer chain (C ≥ 20) omega 3 fatty acids (p < 0.01) and similar plasma levels of alpha-linolenic acid (p = 0.53), omega 6 fatty acids (p > 0.63) and C reactive protein (p = 0.28) then the ones consuming corn oil. There were no differences between fish oil and corn oil diet supplementation on plaque (18.2 vs. 17.8, p = 0.78), calculus (10.1 vs. 11.5, p = 0.18) or gingivitis (19.3 vs. 19.0, p = 0.77) indexes. The authors conclude that supplementation with EPA + DHA does not slow down progression of PD in dogs.