Novel rinse assay for the quantification of oral neutrophils and the monitoring of chronic periodontal disease

Germline mutations in a G protein identify signaling cross-talk in T cells

Humans with monogenic inborn errors responsible for extreme disease phenotypes can reveal essential physiological pathways. We investigated germline mutations in GNAI2, which encodes Gαi2, a key component in heterotrimeric G protein signal transduction usually thought to regulate adenylyl cyclase-mediated cyclic adenosine monophosphate (cAMP) production. Patients with activating Gαi2 mutations had clinical presentations that included impaired immunity. Mutant Gαi2 impaired cell migration and augmented responses to T cell receptor (TCR) stimulation. We found that mutant Gαi2 influenced TCR signaling by sequestering the guanosine triphosphatase (GTPase)-activating protein RASA2, thereby promoting RAS activation and increasing downstream extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)-AKT S6 signaling to drive cellular growth and proliferation.

Toward Digital Periodontal Health: Recent Advances and Future Perspectives

Periodontal diseases, ranging from gingivitis to periodontitis, are prevalent oral diseases affecting over 50% of the global population. These diseases arise from infections and inflammation of the gums and supporting bones, significantly impacting oral health. The established link between periodontal diseases and systemic diseases, such as cardiovascular diseases, underscores their importance as a public health concern. Consequently, the early detection and prevention of periodontal diseases have become critical objectives in healthcare, particularly through the integration of advanced artificial intelligence (AI) technologies. This paper aims to bridge the gap between clinical practices and cutting-edge technologies by providing a comprehensive review of current research. We examine the identification of causative factors, disease progression, and the role of AI in enhancing early detection and treatment. Our goal is to underscore the importance of early intervention in improving patient outcomes and to stimulate further interest among researchers, bioengineers, and AI specialists in the ongoing exploration of AI applications in periodontal disease diagnosis.

Oral and Intestinal Bacterial Flora in Patients with Increased Periodontal Inflamed Surface Area: A Cross-Sectional Study

Background/Objectives: Periodontitis is caused by bacterial plaque. The oral microflora may interact with the intestinal microflora and play a role in the development of periodontitis. The periodontal inflamed surface area (PISA) has been shown to be a useful indicator of periodontal disease related to systemic diseases; however, few studies have shown an association between PISA and the bacterial flora. This study aimed to determine the association between PISA and oral and intestinal bacteria. Methods: Participants were recruited between 2018 and 2021 at the Medical and Dental Collaboration Center of Kanagawa Dental University Hospital. A periodontal clinical examination was performed, and the PISA was calculated. Salivary tests were conducted, and leukocyte scores in the saliva were calculated. Moreover, 16S rRNA amplicon sequencing was performed using saliva and stool samples to analyze oral and intestinal bacteria, respectively. Results: Higher PISA levels resulted in an increased presence of Bacteroides and a decreased presence of Proteobacteria and Actinobacteria in the saliva. An increase in Bacteroides was detected in the saliva of patients with high leukocyte scores. No correlation was observed between PISA and intestinal bacteria. Conclusions: Bacteroides was highly abundant in the saliva of patients with worsened periodontal conditions, as indicated by PISA. No association was found between PISA and intestinal bacteria.

The association between oral inflammatory load and semen and sperm functional analysis: A cross-sectional study

Background

Studies have suggested a correlation between periodontitis and reduced male fertility. Inflammation has been described as the link between these ailments. Oral inflammatory load (OIL) can be measured through oral polymorphonuclear neutrophil (oPMN) count, which is associated with periodontal diseases. This cross-sectional study assessed the possible correlation between OIL and the functional parameters of sperm cells.

Methods

In 229 volunteers, oral rinse and semen samples were assessed for oPMN, semen polymorphonuclears (sPMNs), sperm concentration, total sperm count, motility, morphology, and sperm DNA fragmentation index (SDFi). A multiple linear regression model was conducted to evaluate the relationships between oPMN and semen parameters.

Results

The effect of elevated oPMN counts on total motility rate, progressive rate, and percentage of sperm cells with normal morphology was significant (P<0.001), with an inverse relationship, i.e., with every unit increase in oPMN count, the mentioned parameters would decline by 0.573, 0.367, and 0.407 units, respectively. oPMN counts also correlated positively with sPMN counts and SDFi (P<0.001), i.e., with every unit increase in the oPMN measures, sPMN counts would increase by 0.126 million/mL, with an 0.733% increase in SDFi. However, there was no significant association between oPMN counts and sperm concentration.

Conclusion

OIL, as represented by oPMN counts, might affect male fertility as there is a positive correlation between the levels of these inflammatory cells and decreased sperm motility, abnormal morphological changes, increased sPMN counts, and increased SDFi.

Neutrophil Extracellular Traps Aggravate Apical Periodontitis by Stimulating Osteoclast Formation

INTRODUCTION

Neutrophil extracellular traps (NETs) have been described as structures composed of DNA and proteins, such as elastase and myeloperoxidase, that are able to kill bacteria extracellularly. The aim of the present study was to evaluate the role of NETs in bone resorption observed in pulp infection-induced apical periodontitis in mice.

METHODS

Apical periodontitis was experimentally induced by exposing the dental pulp of the mandibular first molar of mice to the oral microenvironment. The expression of NETs was evaluated by immunofluorescence in mice and biopsies of apical periodontitis. Mice were treated with vehicle or DNase I to degrade NETs, and the samples were collected after 7 days. The size of the apical lesion and the osteoclast number were determined in hematoxylin-eosin- and tartrate-resistant acid phosphatase-stained sections, respectively. Osteoclast differentiation and function markers were evaluated by quantitative polymerase chain reaction. The level of NETs in the serum was determined by the myeloperoxidase-DNA PicoGreen assay.

RESULTS

We first confirmed the presence of neutrophils and NETs at the site of the lesion in mice and in biopsies of patients with apical periodontitis. The treatment of mice with DNase I reduced the level of NETs in the serum and led to a reduction in apical lesion size and alveolar bone resorption. This effect was associated with a reduction of local inflammatory infiltrate and a reduced number of osteoclasts. We found that the increased expression of Acp5, Ctsk, and Rankl genes associated with osteoclast formation and function were abrogated by the absence of NETs.

CONCLUSIONS

Our data highlight NETs as an important player in the pathogenesis of apical periodontitis with regard to the local inflammation and consequent bone resorption after pulp infection.

Quantification of oral neutrophil counts in periodontal health and disease utilising a standardised oral rinse

Background and Objectives

Polymorphonuclear neutrophils are the most abundant leukocytes in humans and are key host cells in defence against invading microorganisms. The oral neutrophil count may be an indicator of the periodontal health status, which correlates with the severity of periodontal disease. This study attempts to quantify orogranulocytes utilising an oral rinse and to assess the usefulness of this method in evaluating the oral inflammatory load much the same way the circulating neutrophils are used to screen for patients with infection in extra-oral sites.

Methods

A total of 125 participants were divided into five groups with 25 subjects in each group. The groups consisted of healthy, gingivitis, mild periodontitis, moderate periodontitis, and severe periodontitis. Participants were asked to rinse with 10 mL of 0.9% saline for 30 s and to expectorate. Samples were centrifuged at 2000 RPM for 10 min. The supernatant removed was suspended in 5 mL of Hanks's balanced salt solution. One millilitre of this suspension was mixed with 4 μL of acridine orange. A 10 μL aliquot of this suspension was then assessed on a haemocytometer, and the oral PMNs were counted using fluorescence microscopy.

Results

The mean number of oral neutrophils (100,000 cells/mL) was the lowest in the healthy group and increased in ascending order across the different groups with the highest for severe periodontitis group.

Conclusion

The oral neutrophil counts increased with the severity of periodontal inflammation. This is an easy, safe, reliable, and non-invasive method of quantification of oral neutrophils.

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.

Oral inflammatory load predicts vascular function in a young adult population: a pilot study

Background

The periodontium is a highly vascularized area of the mouth, and periodontitis initiates negative functional and structural changes in the vasculature. However, mild oral inflammation, including levels experienced by many apparently healthy individuals, has an unclear impact on cardiovascular function. The purpose of this pilot study is to investigate the effects of objectively measured whole mouth oral inflammatory load (OIL) on vascular function in apparently healthy individuals.

Methods

In this cross-sectional and correlational analysis, we recruited 28 young (18-30 years) and systemically healthy participants (16 male, 12 female). Using oral neutrophil counts, a validated measure for OIL, we collected participant's mouth rinse samples and quantified OIL. Blood pressure, arterial stiffness (pulse-wave velocity) and endothelial function (brachial artery flow-mediated dilation) were also measured.

Results

Only oral neutrophil count significantly predicted flow-mediated dilation % (p = 0.04; R2 = 0.16, β = - 1.05) and those with OIL levels associated with >2.5 × 105 neutrophil counts (n = 8) had a lower flow-mediated dilation % (6.0 ± 2.3%) than those with counts associated with gingival health with less than 2.5 × 105 neutrophil counts (10.0 ± 5.2%, p = 0.05). There were no significant predictors for arterial stiffness.

Conclusion

We found that OIL was a predictor of reduced flow-mediated dilation. An impairment in flow-mediated dilation is an indicator of future possible risk of cardiovascular disease-one of the leading causes of death in North America. Therefore, this study provides evidence for the importance of oral health and that OIL may impact endothelial function.

The influence of smoking on oral neutrophils and matrix metalloproteinase-8 in periodontitis patients before and after nonsurgical treatment

Objective

To evaluate and compare the oral neutrophil numbers (ONN) in saliva, the level of matrix metalloproteinase-8 (MMP-8) in gingival crevicular fluid (GCF) and the periodontal parameters in smokers versus non-smokers with periodontitis, before and after nonsurgical periodontal treatment (NSPT).

Materials and method

40 chronic periodontitis patients including 20 smokers and 20 non-smokers were enrolled in this quasi-experimental study. All patients were received the NSPT included instructing oral hygiene, scaling and root planing. At baseline (T0) and after NSPT 1 month (T1) and 3 months (T3), all patients were assessed for salivary ONN, GCF MMP-8, and clinical parameters like plaque index (PlI), gingival index (GI), bleeding on probing (BOP), probing pocket depth (PPD) and clinical attachment loss (CAL). The differences between the two groups were analyzed using the independent sample t-test and the Mann-Whitney U test; and the differences between T0, T1 and T3 of each group were analyzed with paired-samples t-test and Wilcoxon signed-rank test. The level of significance was set at 0.05.

Results

The ONN was significantly less in smokers than in non-smokers although there was no significant difference in other parameters between the two groups at baseline (p > 0.05). All clinical periodontal parameters reduced significantly after 1 month and 3 months of NSPT in both groups (p < 0.01). PPD of non-smokers was significantly lower than those of smokers at T1 and T3. ONN and MMP-8 level showed a significant decrease in non-smoking subjects, while there was no significant difference in smoking ones after NSPT (T1 and T3). At 1 month after treatment, ONN tended to reduce in non-smokers whereas to increase in smokers significantly.

Conclusion

Smoking reduced ONN, impaired treatment effect in reducing PPD, and changed the MMP-8 level in gingival crevicular fluid to NSPT.

Trial registration

Identifier NCT04974502 in CLinicalTrials.gov.

"The Standard Procedure" for Investigation of Oral Neutrophils in Oral Diseases

Aim

There is need of an objective "standard procedure" that is reliable and clinically applicable for estimating oral neutrophil content in relation to oral diseases.

Methods

Forty-one patients with suspected oral candidosis (OC) and nine healthy controls with no oral mucosal disease were flushing with 10 ml mouth rinse (MR) (sterile phosphate-buffered saline) for 1 min. Aliquots were stored on different conditions to explore stability, storage, and fixation conditions for analysis by flow cytometry.

Results

The optimal storage and fixation condition for MR was by fixation 1 : 1 in 10% formalin and stored at 5°C. This procedure yielded stable results up to 7 days after collection. The ability of the optimized method to relate oral neutrophils to inflammation was demonstrated by the significantly higher number of neutrophils in patients with primary OC (p = 0.0334) compared to healthy controls.

Conclusion

This method is rapid, reliable, and clinically applicable for establishing the content of oral neutrophils. We demonstrate increased density of oral neutrophils in the MR of patients with OC. The potential of the method is to be "the standard procedure" for investigation of the oral inflammation in patients with oral diseases as it is noninvasive and provides high stability, clinical relevance, and minimal handling.

The Association between Maternal Oral Inflammation and Neutrophil Phenotypes and Poly-Unsaturated Fatty Acids Composition in Human Milk: A Prospective Cohort Study

This prospective cohort study aimed to investigate the impact of maternal oral inflammation on human milk composition including neutrophil counts, activation state (based on cluster of differentiation (CD) markers expression), and fatty acid levels. Fifty mothers were recruited from St. Michael's hospital, Toronto, and followed up from 2-4 weeks until 4 months postpartum. Oral rinse and human milk samples were collected at both timepoints. Oral polymorphonuclear neutrophils (oPMNs) within the rinses were quantified using flow cytometry and the participants' oral health state was categorized into three groups (i.e., healthy, moderate, and severe) based on the oPMNs counts. Fatty acids were identified and quantified using a gas chromatography-flame ionization detector (GC-FID). Compared to mothers with a healthy oral health state, mothers with moderate to severe oral inflammation had a statistically significant decrease in the expression of CD64 biomarker, an increase in the expression of CD14 biomarker on human milk neutrophils and a decrease in the levels of eicosapentaenoic acid (C20:5n-3) in their human milk at follow-up compared to baseline. This study demonstrates for the first time that maternal oral inflammation can affect human milk composition. The mechanism by which these alterations can affect infant health outcomes in the long term critically needs to be considered.

Severe alveolar bone resorption in Felty syndrome: a case report

BACKGROUND

Felty syndrome is defined by three conditions: neutropenia, rheumatoid arthritis, and splenomegaly. Neutropenia associated with pancytopenia may further affect the dental condition of a patient. Periodontal treatment and surgery in patients with Felty syndrome necessitates cooperation with a hematologist. Here we present a case of a patient with Felty syndrome who was initially referred to the oral surgery hospital attached to the School of Dentistry for extensive periodontitis. She was effectively treated in collaboration with the hematology department.

CASE PRESENTATION

A 55-year-old Asian woman visited our department with concerns of worsening tooth mobility, discomfort, and spontaneous gingival bleeding. Initial periodontal examination revealed generalized severe periodontitis (Stage IV Grade C) resulting from leukopenia/neutropenia and poor oral hygiene. A thorough treatment strategy involving comprehensive dental procedures, such as multiple extractions and extensive prosthetic treatment, was implemented. Following the diagnosis of Felty syndrome, the patient was started on treatment with oral prednisolone 40 mg/day, which effectively controlled the disease. Furthermore, there was no recurrence of severe periodontitis after the periodontal treatment.

CONCLUSIONS

Dentists and physicians should be aware that immunocompromised individuals with pancytopenia and poor oral hygiene are at risk of developing extensive periodontitis. If their susceptibility to infection and pancytopenia-related bleeding can be managed, such patients can still receive comprehensive dental treatment, including teeth extractions and periodontal therapy. Cooperation among the dentist, hematologist, and patient is necessary to improve treatment outcomes and the patient's quality of life.

Metronidazole enhances killing of Porphyromonas gingivalis by human PMNs

Background and objectives

Periodontitis affects the supporting structures of the teeth as a result of the interactions between the subgingival biofilm and the host immune system. Periodontal therapy in severe forms of periodontitis often utilizes antimicrobial agents with some potential to improve host defense responses. In the present study, we investigated the in vitro effect of metronidazole (MTZ) at concentrations achievable in the periodontal pocket on PMN activation and PMN mediated killing of Porphyromonas gingivalis.

Materials and methods

Flow cytometry based assays were used to measure the impact of MTZ on PMN degranulation, neutrophil extracellular trap (NET) formation and myeloperoxidase (MPO) release and phagocytosis in response to the keystone oral pathogen P. gingivalis. Functional assays for PMN mediated killing of P. gingivalis and reactive oxygen species (ROS) production in PMN were also carried out.

Results

We demonstrate that PMNs pretreated with MTZ (2 μg/ml or 50 μg/ml) displayed enhanced killing of P. gingivalis compared to untreated PMNs. At concentrations achieved physiologically in the periodontal pocket, MTZ induced PMN surface expression of two activation markers (CD66 and CD63). MTZ did not alter P. gingivalis-induced NETosis, but suppressed P. gingivalis-induced ROS production and phagocytosis.

Conclusion

MTZ displays a positive interaction with PMNs to potentiate PMN mediated killing of P. gingivalis and may therefore contribute to its beneficial effects in the treatment of periodontitis initiated by P. gingivalis infections including those refractory to conventional treatment.

The Effect of Intensity-Modulated Radiotherapy to the Head and Neck Region on the Oral Innate Immune Response and Oral Microbiome: A Prospective Cohort Study of Head and Neck Tumour Patients

Neutrophils, also known as polymorphonuclear leukocytes (PMNs), form a significant component of the innate host response, and the consequence of the interaction between the oral microbiota and PMNs is a crucial determinant of oral health status. The impact of radiation therapy (RT) for head and neck tumour (HNT) treatment on the oral innate immune system, neutrophils in particular, and the oral microbiome has not been thoroughly investigated. Therefore, the objective of this study was to characterize RT-mediated changes in oral neutrophils (oPMNs) and the oral microbiome in patients undergoing RT to treat HNTs. Oral rinse samples were collected prior to, during and post-RT from HNT patients receiving RT at Dental Oncology at Princess Margaret Cancer Centre. The oPMNs counts and activation states were analysed using flow cytometry, and the oral microbiome was analysed using 16S rRNA gene sequencing. Statistically significant (p < 0.05) drops in oPMN counts and the activation states of the CD11b, CD16, CD18, CD64 and H3Cit markers from pre-RT to post-RT were observed. Moreover, exposure to RT caused a significant reduction in the relative abundance of commensal Gram-negative bacteria and increased the commensal Gram-positive microbes. Ionizing radiation for the treatment of HNTs simultaneously decreased the recruitment of oPMNs into the oral cavity and suppressed their activation state. The oral microbiome composition post-RT was altered significantly due to RT which may favour the colonization of specific microbial communities unfavourable for the long-term development of a balanced oral microbiome.

Innate Phagocyte Polarization in the Oral Cavity

The oral cavity is a complex environment constantly exposed to antigens from food and the oral microbiota. Innate immune cells play an essential role in maintaining health and homeostasis in the oral environment. However, these cells also play a significant role in disease progression. This review will focus on two innate phagocytes in the oral cavity: macrophages and neutrophils, and examine their roles during homeostasis and disease development, with a focus on periodontal disease and cancer. Macrophages have a well-known ability to polarize and be activated towards a variety of phenotypes. Several studies have found that macrophages’ polarization changes can play an essential role in maintaining health in the oral cavity and contribute to disease. Recent data also finds that neutrophils display phenotypic heterogeneity in the oral cavity. In both cases, we focus on what is known about how these cellular changes alter these immune cells’ interactions with the oral microbiota, including how such changes can lead to worsening, rather than improving, disease states.

The Differential Reactive Oxygen Species Production of Tear Neutrophils in Response to Various Stimuli In Vitro

A large number of polymorphonuclear neutrophils (PMNs) invade the ocular surface during prolonged eye closure (sleep); these leukocytes are commonly referred as tear PMNs. PMNs contribute to homeostasis and possess an arsenal of inflammatory mediators to protect against pathogens and foreign materials. This study examined the ability of tear PMNs to generate reactive oxygen species (ROS), an essential killing mechanism for PMNs which can lead to oxidative stress and imbalance. Cells were collected after sleep from healthy participants using a gentle eye wash. ROS production in stimulated (phorbol-12-myristate-13-acetate (PMA), lipopolysaccharides (LPS) or N-Formylmethionyl-leucyl-phenylalanine (fMLP)) and unstimulated tear PMNs was measured using luminol-enhanced chemiluminescence for 60 min. A high level of constitutive/spontaneous ROS production was observed in tear PMNs in the absence of any stimulus. While tear PMNs were able to produce ROS in response to PMA, they failed to appropriately respond to LPS and fMLP, although fMLP-stimulated tear PMNs generated ROS extracellularly in the first three minutes. Higher ROS generation was observed in isolated tear PMNs which may be due to priming from the magnetic bead cell separation system. The differential responses of tear PMNs in ROS generation provide further evidence of their potential inflammatory roles in ocular complications involving oxidative stress.

Human and herpesvirus microRNAs in periodontal disease

Periodontitis is a multi-etiologic infection characterized clinically by pathologic loss of the periodontal ligament and alveolar bone. Herpesviruses and specific bacterial species are major periodontal pathogens that cooperate synergistically in producing severe periodontitis. Cellular immunity against herpesviruses and humoral immunity against bacteria are key periodontal host defenses. Genetic, epigenetic, and environmental factors are modifiers of periodontal disease severity. MicroRNAs are a class of noncoding, gene expression-based, posttranscriptional regulatory RNAs of great importance for maintaining tissue homeostasis. Aberrant expression of microRNAs has been associated with several medical diseases. Periodontal tissue cells and herpesviruses elaborate several microRNAs that are of current research interest. This review attempts to conceptualize the role of periodontal microRNAs in the pathogenesis of periodontitis. The diagnostic potential of salivary microRNAs is also addressed. Employment of microRNA technology in periodontics represents an interesting new preventive and therapeutic possibility.

Reductions in clinical inflammation and oral neutrophils with improving oral hygiene

OBJECTIVE

This study compared the effects of oral hygiene with a toothpaste formulated with zinc (test) to a fluoride dentifrice (control) for effects on oral polymorphonuclear leukocyte (PMN) as a measure of whole mouth inflammation along with effects on clinical parameters of dental plaque and gingivitis.

MATERIALS AND METHODS

Adults (age range 18-60 years, n = 212) completed this double-blind, parallel design study. After washout, a baseline oral rinse sample was evaluated for PMN prior to clinical assessments for gingivitis and dental plaque. Subjects were randomly assigned to brush twice daily with either the test or the control toothpaste. Post-treatment evaluations repeated all baseline assessments after 4-week, 6-week and 12-week use of dentifrice with all assessments conducted 12 hours after brushing.

RESULTS

PMN reductions in the test were 16.8%, 18.7% and 42.5% at the 4-week, 6-week and 12-week evaluations respectively and significantly different from the control (p < 0.05). The test toothpaste also demonstrated progressively increasing reductions in gingivitis and dental plaque that ranged from 7.6 to 33.3% and 2.3 to 9.1% respectively versus the control (p < 0.05).

CONCLUSIONS

The test dentifrice demonstrated progressive reductions in oral PMN representing whole mouth inflammation in conjunction with improvements in oral hygiene as compared to the control toothpaste.

CLINICAL RELEVANCE

A hallmark of oral inflammation includes the accumulations of PMN in the afflicted gingival regions to reduce the influences of proliferating microorganisms. Brushing with a zinc dentifrice demonstrated progressive reductions in oral PMN and improvements in oral hygiene as evidenced by progressively lower dental plaque and gingival indices.

Stressed-Out Oral Immunity: A Gateway From Socioeconomic Adversity to Periodontal Disease

OBJECTIVE

It has been suggested that adverse socioeconomic conditions "get under the skin" by eliciting a stress response that can trigger periodontal inflammation. We aimed to a) estimate the extent to which socioeconomic position (SEP) is associated with periodontal disease (PD) and proinflammatory oral immunity, and b) determine the contribution of psychosocial stress and stress hormones to these relationships.

METHODS

In this cross-sectional study (n = 102), participants (20-59 years old) completed financial and perceived stress questionnaires and underwent full-mouth periodontal examinations. SEP was characterized by annual household income and educational attainment. Cortisol, a biological correlate of chronic stress, was assessed in hair samples. Oral immunity was characterized by assessing oral inflammatory load and proinflammatory oral neutrophil function. Blockwise Poisson and logistic regression models were applied.

RESULTS

Compared with lower SEP, individuals in the middle- and higher-income categories had a significantly lower probability of PD (incidence rate ratio [IRR] = 0.5 [confidence interval {CI} = 0.3-0.7] and IRR = 0.4 [95% CI = 0.2-0.7]) and oral inflammatory load (IRR = 0.6 [95% CI = 0.3-0.8] and IRR = 0.5 [95% CI = 0.3-0.7]) and were less likely to have a proinflammatory oral immune function (odds ratio [OR] = 0.1 [95% CI = 0.0-0.7] and OR = 0.1 [95% CI = 0.0-0.9]). PD and oral immune parameters were significantly associated with financial stress and cortisol. Adjusting for financial stress and cortisol partially attenuated the socioeconomic differences in PD to IRR = 0.7 (95% CI = 0.5-0.8) and IRR = 0.6 (95% CI = 0.5-0.7) for the middle- and higher-income categories, respectively. Similar results were observed for proinflammatory immunity (OR = 0.2 [95% CI = 0.0-1.8] and OR = 0.3 [95% CI = 0.0-2.3]).

CONCLUSION

These findings suggest that psychosocial stress may contribute to a proinflammatory immunity that is implicated in PD pathobiology and provide insight into social-to-biological processes in oral health.

Periodontal Pathogens' strategies disarm neutrophils to promote dysregulated inflammation

Periodontitis is an irreversible, chronic inflammatory disease where inflammophilic pathogenic microbial communities accumulate in the gingival crevice. Neutrophils are a major component of the innate host response against bacterial challenge, and under homeostatic conditions, their microbicidal functions typically protect the host against periodontitis. However, a number of periodontal pathogens developed survival strategies to evade neutrophil microbicidal functions while promoting inflammation, which provides a source of nutrients for bacterial growth. Research on periodontal pathogens has largely focused on a few established species: Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis. However, advances in culture-independent techniques have facilitated the identification of new bacterial species in periodontal lesions, such as the two Gram-positive anaerobes, Filifactor alocis and Peptoanaerobacter stomatis, whose characterization of pathogenic potential has not been fully described. Additionally, there is not a full understanding of the pathogenic mechanisms used against neutrophils by organisms that are abundant in periodontal lesions. This presents a substantial barrier to the development of new approaches to prevent or ameliorate the disease. In this review, we first summarize the neutrophil functions affected by the established periodontal pathogens listed above, denoting unknown areas that still merit a closer look. Then, we review the literature on neutrophil functions and the emerging periodontal pathogens, F. alocis and P. stomatis, comparing the effects of the emerging microbes to that of established pathogens, and speculate on the contribution of these putative pathogens to the progression of periodontal disease.

Investigation of the response of tear-film neutrophils to interleukin 8 and their sensitivity to centrifugation, fixation, and incubation

During eye closure, a large number of neutrophils (polymorphonuclear neutrophils, PMNs) invade the ocular surface and are often referred to as tear-film PMNs. While immunophenotyping experiments have been performed on tear-film PMNs, the impact of commonly used experimental procedures on their phenotype as well as their response to interleukin-8 (IL-8), a physiological inflammatory mediator, have not yet been investigated. A gentle eye wash method was used to collect cells at home. In the morning upon awaking, participants washed their eyes with sterile phosphate buffer saline (PBS) and collected the runoff into a sterile polypropylene tube. The cell collection was then delivered to the lab within two hours. The effects of centrifugation, incubation and fixation with paraformaldehyde (PFA) before (pre-fixed staining) or after (post-fixed staining) incubation with antibodies were characterized. Tear-film PMNs as well as blood PMNs (used for comparison) were also stimulated with IL-8. To assess the reproducibility of cell collection and variability in receptor expression over time, participants were also asked to collect cells three times over a period of a month. The change in expression of surface receptors, CD11b, CD16, CD55, CD66b, important inflammatory and activation markers, and CD45 (PAN leukocyte marker) was assessed by flow cytometry. Fixing tear-film PMNs prior to the staining with antibodies resulted in a significant (fivefold or more) reduction in the expression of CD11b, CD16 and CD45 when compared to unfixed samples, while CD16 was the only receptor to undergo significant downregulation upon post-staining fixation. Furthermore, additional centrifugation step prior to antibody incubation as well as long (4 h) incubation at 37 °C resulted in significant reductions in expression of CD11b, CD16 and CD55 when compared to control samples. As opposed to blood PMNs, stimulating tear-film PMNs with IL-8 did not induce any significant changes in expression of CD11b, CD16, CD55 and CD66b. When working with collected tear-film PMNs, our results suggest that any additional centrifugation and incubation step should be avoided, or at least limited, and post fixation staining is recommended in order to preserve cell phenotype and cell integrity of tear film PMNs. Our study also adds further information on the reproducibility of the gentle eye wash as well as the inability of tear-film PMNs to modulate their surface receptors upon stimulation with IL-8. The latter may be due to prior exposure to IL-8, activation in the closed-eye environment, or a reduced ability to respond to inflammatory stimulus. Further mechanistic studies will be needed to gain a better understanding of the tear-film neutrophil phenotype.

Maternal periodontal status, oral inflammatory load, and systemic inflammation are associated with low infant birth weight

BACKGROUND

Periodontal disease and pregnancy outcomes have been claimed to be associated with conflicting reports. The purpose of this study was to prospectively examine the association between maternal periodontal status, oral inflammatory load and serum C- reactive protein (CRP) level, and infant birth weight.

METHODS

A total of 156 pregnant women (age 26.62 ± 3.93 years) within the gestational age group of 13 to 32 weeks participated in this cross-sectional study. Oral inflammatory load (OIL) was assessed in a salivary rinse sample using fluorescence microscopy. Clinical periodontal parameters were recorded and serum C-reactive protein level (CRP) was assessed. Participants were followed till delivery, details of parturition and infant birth weight (IBW) was recorded.

RESULTS

OIL was significantly more in participants with mild and moderate periodontitis as compared to those with gingivitis in mid and late stages of pregnancy. Periodontal and systemic inflammatory parameters were positively correlated. A significant negative correlation was found between IBW and OIL (P = 0.006) and serum CRP (P < 0.001). The GI score (P = 0.039), BOP% (P = 0.023), serum CRP level (P < 0.001) and oral polymorphonuclear neutrophil (oPMN) count (P < 0.001) was significantly more in mothers delivering babies with low IBW. A multiple linear regression analysis showed that only oPMN (β = - 0.244, P = 0.021) and serum CRP (β = - 0.226, P = 0.019) were included in the best model (R²  = 0.12, F(3,152) = 7.15, P < 0.001) for significantly predicting the infant birth weight.

CONCLUSIONS

Poor maternal periodontal status, increased oral inflammatory load and increased systemic inflammation have an adverse effect on infant birth weight.

Human neutrophils compromise the restoration-tooth interface

Neutrophils, cells of the innate immune system, enter the mouth and release factors that are hypothesized to contribute to the degradation of tooth dentin, methacrylate resin composites, and adhesives at the restoration-tooth-dentin interface. The objectives were to characterize neutrophils' degradation towards resin composite, self-etch (SE) and total-etch (TE) adhesives, SE and TE resin-dentin interfaces and to identify proteins that could contribute to the degradation process. Neutrophils' degradation of cured resin composite, and SE and TE adhesives, was quantified by measuring the specific resin degradation by-product, bishydroxy-propoxy-phenyl-propane (bisHPPP), released after 30 days incubation of the materials with the cells. Neutrophils' degradative effect on resin-dentin interfaces was examined by recording the interfacial fracture toughness (FT), and surface analysis of the fracture mode following incubation of SE and TE miniature short-rod (mini-SR) specimens with the cells. Neutrophils increased degradation of polymerized resin composite, and TE adhesive, but not SE adhesive over 30 days (p < 0.05). Incubation of SE and TE resin-dentin interfaces with neutrophils led to a reduction in FT over time (p < 0.05). The effect was more pronounced for TE interfaces. Neutrophils also affected the fracture mode of SE and TE resin-dentin interfaces. Several proteins that could contribute to the degradative activity of neutrophils, including Neutrophil collagenase (MMP-8), Matrix metalloproteinase- 9 (MMP-9), Cathepsin G, Neutrophil- gelatinase associated lipocalin (NGAL) and Myeloperoxidase, were isolated. The ability of neutrophils to degrade resin, tooth dentin, and reduce the bond strength of resin-dentin interfaces suggest neutrophils' potential role in primary and recurrent caries and dental restoration failure.

The Neutrophil: Constant Defender and First Responder

The role of polymorphonuclear neutrophils (PMNs) in biology is often recognized during pathogenesis associated with PMN hyper- or hypo-functionality in various disease states. However, in the vast majority of cases, PMNs contribute to resilience and tissue homeostasis, with continuous PMN-mediated actions required for the maintenance of health, particularly in mucosal tissues. PMNs are extraordinarily well-adapted to respond to and diminish the damaging effects of a vast repertoire of infectious agents and injurious processes that are encountered throughout life. The commensal biofilm, a symbiotic polymicrobial ecosystem that lines the mucosal surfaces, is the first line of defense against pathogenic strains that might otherwise dominate, and is therefore of critical importance for health. PMNs regularly interact with the commensal flora at the mucosal tissues in health and limit their growth without developing an overt inflammatory reaction to them. These PMNs exhibit what is called a para-inflammatory phenotype, and have reduced inflammatory output. When biofilm growth and makeup are disrupted (i.e., dysbiosis), clinical symptoms associated with acute and chronic inflammatory responses to these changes may include pain, erythema and swelling. However, in most cases, these responses indicate that the immune system is functioning properly to re-establish homeostasis and protect the status quo. Defects in this healthy everyday function occur as a result of PMN subversion by pathological microbial strains, genetic defects or crosstalk with other chronic inflammatory conditions, including cancer and rheumatic disease, and this can provide some avenues for therapeutic targeting of PMN function. In other cases, targeting PMN functions could worsen the disease state. Certain PMN-mediated responses to pathogens, for example Neutrophil Extracellular Traps (NETs), might lead to undesirable symptoms such as pain or swelling and tissue damage/fibrosis. Despite collateral damage, these PMN responses limit pathogen dissemination and more severe damage that would otherwise occur. New data suggests the existence of unique PMN subsets, commonly associated with functional diversification in response to particular inflammatory challenges. PMN-directed therapeutic approaches depend on a greater understanding of this diversity. Here we outline the current understanding of PMNs in health and disease, with an emphasis on the positive manifestations of tissue and organ-protective PMN-mediated inflammation.

Hyposalivation is prevalent in bariatric patients but improves after surgery

BACKGROUND

Obesity and type 2 diabetes can be associated with poor oral health. This can be because of hyposalivation leading to chronic oral inflammation (OI) and periodontal disease.

OBJECTIVE

To assess the prevalence of hyposalivation and OI in individuals undergoing Roux-en-Y gastric bypass (RYGB) and determine the relationship with metabolic and anthropometric parameters before and after RYGB.

SETTING

University hospital in Canada.

METHODS

This was a cross-sectional and prospective cohort study of 59 patients undergoing RYGB from September 2015 to December 2019. Anthropometric, biochemical, and oral measurements were taken before surgery and 1 and 6 months post RYGB. Oral parameters included salivary flow rate and neutrophil count as marker of OI.

RESULTS

Fifty-nine patients were enrolled with 29 completing this study. At baseline, the median age was 47 years and body mass index was 46.5 kg/m², 52 (88.1%) were female and 14 individuals (23.7%) had type 2 diabetes; 54.2% (n = 32) of patients had hyposalivation and 13.6% (n = 8) had high neutrophil count. Patients with hyposalivation had significantly higher fasting glucose (5.7 mmol/L) compared with those without hyposalivation (5.2 mmol/L) but no difference was found between high versus low neutrophil count. At 6 months post RYGB, all variables except oral neutrophil count significantly improved. Hyposalivation persisted in 7 (24%) individuals.

CONCLUSIONS

In our bariatric patients, more than half the patients had hyposalivation before RYGB and this was associated with higher fasting glucose. Hyposalivation improved post RYGB in parallel with improvements in metabolic parameters but there was no change in OI. Increased salivation may reduce the risk of periodontal disease.

Primed PMNs in healthy mouse and human circulation are first responders during acute inflammation

Polymorphonuclear neutrophils (PMNs) are the most abundant circulating leukocytes, and the first cells recruited to sites of tissue inflammation. Using a fixation method to preserve native CD marker expression prior to immunophenotyping, we identified a distinct population of "primed for recruitment" PMNs in healthy mouse and human blood that has high expression of adhesion and activation markers compared with the bulk resting-state PMNs. In response to acute tissue inflammation, primed PMNs (pPMNs) were rapidly depleted from the circulation and recruited to the tissue. One hour after acute peritoneal insult, pPMNs became the dominant PMN population in bone marrow (BM) and blood, returning to baseline levels with resolution of inflammation. PMN priming was induced by the granulopoietic factors granulocyte-macrophage-colony-stimulating factor (GM-CSF) and granulocyte-colony-stimulating factor (G-CSF). High levels of pPMNs were observed in neutropenic mice and in pediatric neutropenic patients who were resistant to infection, highlighting an important role of this population in innate immune function.

Dentistry and OMICS: Transcriptome Dynamics of an Oral Ecosystem as Measured by Changes in Oral Polymorphonuclear Neutrophils in Experimental Gingivitis

Oral health and dentistry are essential components of systems medicine, which has received lesser attention in comparison to other medical fields, such as cancer biology. In this context, oral polymorphonuclear neutrophils (oPMNs) play an important role in the maintenance of oral health. To the best of our knowledge, this is the first study to report original observations on the transcriptional responses of oPMNs during experimentally induced gingivitis, by temporarily refraining from regular oral care. Oral rinses were prospectively collected at four different time points for oPMNs isolation from healthy volunteers: day 1 (start of the experimental gingivitis challenge), day 9 (during challenge), day 14 (end of the challenge), and day 21 (postchallenge). Transcriptome of oPMNs was determined by RNA sequencing. Differentially expressed genes (DEGs) were selected at p < 0.01 level, and evaluated for pathway regulation using Ingenuity Pathway Analysis suite. We found four major clusters of DEGs, consisting of 256 initial response DEGs (day 9 only), 221 late response DEGs (day 14 only), 53 persistent responsive DEGs (consistent at day 9 and 14), and 524 DEGs showing responses only in the postchallenge phase (day 21 only). Pathway analysis of the initial and late response DEGs showed involvement in many immune regulatory pathways and PMN function, whereas DEGs at day 21 were associated with epithelial adherence signaling and other miscellaneous related signaling pathways. The results from this pilot study showed that oPMNs mediate oral inflammatory processes, suggesting their immunomodulatory role in oral equilibrium.

Oral inflammatory load: Neutrophils as oral health biomarkers

Periodontal diseases present a significant challenge to our healthcare system in terms of morbidity from the disease itself as well as their putative and deleterious effects on systemic health. The current method of diagnosing periodontal disease utilizes clinical criteria solely. These are imprecise and are somewhat invasive. There is thus significant benefit to creating a non-invasive test as a method of screening for and monitoring of periodontal diseases, and, in particular, chronic periodontitis. Oral polymorphonuclear neutrophil (oPMN) counts have been found to correlate with extent of oral inflammation and the presence and severity of periodontal diseases. Potentially then, quantification of oPMNs might be used to identify and measure the severity of oral inflammation (oral inflammatory load; OIL) in subjects with healthy and inflamed periodontal tissues, demonstrating a positive correlation between higher oPMN counts and the extent/severity of OIL. These findings support the development and utilization of a non-invasive chair-side test enabling rapid, accurate, and objective screening of OIL based on measurement of oPMN numbers (similar to white blood cell levels in blood as used in medicine for assessment of infection). The use of such a test before, during, and after treatment of gingivitis and periodontitis could lead to improvements in timing of intervention (ie, when inflammation is active) thereby reducing long-term morbidity.

Effects of a chlorhexidine mouthwash on clinical parameters of gingivitis, dental plaque and oral polymorphonuclear leukocytes [PMN]

Histological features of oral inflammation include infiltration of polymorphonuclear leukocytes [PMN], however studies have not examined the effects of interventions mitigating inflammation on oral PMN. Methods: This double-blind clinical study examined the effects of rinsing with mouthwashes formulated with chlorhexidine [CHX], an ingredient widely utilized in the dental clinic in comparison to a control on oral PMN representing a novel measure of inflammation. A concurrent evaluation of dental plaque and gingival inflammation using widely accepted clinical indices was included in the study. The study enrolled adult subjects providing informed consent, met study criteria and registered gingival index scores of 1.0 or more at the screening visit. Subjects [n = 90; age range 19–58 years] completed a washout phase prior to baseline evaluations for PMN and clinical assessments for dental plaque and gingivitis. Treatments [CHX or a control mouthwash] were randomly assigned to subjects for twice-daily use for the next two weeks. Post-treatment evaluations similar to baseline were conducted after one and two week use of assigned treatment. Results: At baseline, no statistically significant differences between treatment groups for PMN or clinical indices for dental plaque or gingivitis were noted. Rinsing with CHX demonstrated significant reductions for PMN and dental plaque, gingivitis in comparison to the control group. After one and two week use of CHX, PMN demonstrated a 35.9% and 54.9% reduction respectively in comparison to the control group representing significant differences [p < 0.05]. At the one and two week post-treatment evaluations, rinsing with CHX demonstrated 15% and 25% reductions in gingivitis respectively and were significantly different from the control [p < 0.05]. Rinsing with CHX also demonstrated significant reductions in dental plaque of 15% and 19% at the one and two-week post-treatment evaluations respectively in comparison to the control [p < 0.05]. The CHX group also demonstrated reductions in interproximal scores and registered the lowest frequency of gingival index or dental plaque scores on all oral surfaces. Conclusions: Results outline an objective approach to evaluate oral inflammation demonstrating a large and sustained reduction in oral PMN by CHX with these outcomes numerically higher than a clinical index evaluating gingivitis.

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Enumeration of oral polymorphonuclear leukocytes [PMN] estimates the oral inflammatory burden.

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Rinsing with chlorhexidine demonstrated progressive PMN reductions corroborating gingivitis and dental plaque evaluations.

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Rapid PMN assessment provides objective assessment of treatment effects applicable for dental chair-side setting.

Photonic Therapy in Periodontal Diseases an Overview with Appraisal of the Literature and Reasoned Treatment Recommendations

Recent reviews and meta-analyses of the literature over the past quarter-century have failed to provide enough evidence to prove or disprove the actual utility of photonic therapy in periodontitis, alone or adjunctive to conventional approaches. This apparent paradox has been explained by the many physical, molecular, biological, anatomical, and technical variables of photonic treatments, which can differ in light-emitting devices (laser or LED), wavelengths, irradiation power and modes, clinical objectives, follow-up times, disease grading, and assessment methods. This multi-faceted, controversial scenario has led practitioners to underestimate the actual potential of photonic therapy in periodontal diseases. In this critical appraisal of the literature, we have briefly summarized the main photonic therapies and instruments used in Periodontology, highlighting their main characteristics and limitations. Then, we have tried to identify and discuss the key methodological issues which can have an impact on the outcome of photonic therapies. Our main goal was to identify the best parameters, settings, and methodologies to perform effective periodontal photonic treatments and to extrapolate some recommendations for clinical use. Should these recommendations find a consensus among periodontologists and be adopted in future clinical studies, they will hopefully contribute to dissipate the present confusion and uncertainty on this complex matter.

Human neutrophils degrade methacrylate resin composites and tooth dentin

Cholesterol esterase-like (CE) activity from saliva and esterase from cariogenic bacteria hydrolyze ester linkages of dental methacrylate resins. Collagenolytic, matrix metalloproteinase-like (MMP) activities from dentin and bacteria degrade collagen in demineralized tooth dentin. Human neutrophils in the oral cavity contain factors that are hypothesized to have CE and MMP activities that could contribute to the degradation of methacrylate resins and dentinal collagen. OBJECTIVES: To measure the CE and MMP activities from human neutrophils and their ability to degrade dental methacrylate resin composite and dentinal collagen. Neutrophils' CE and MMP activities were measured using nitrophenyl-esters or fluorimetric MMP substrates, respectively. Neutrophils' degradation of resin composite and dentinal collagen was quantified by measuring release of a universal 2,2-Bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (bisGMA)-derived resin composite degradation byproduct, bishydroxy-propoxy-phenyl-propane (bisHPPP), or a collagen degradation by-product, hydroxyproline, respectively using ultra performance liquid chromatography/mass spectrometry. Neutrophils' CE activity increased the release of bisHPPP from bisGMA monomer compared to control after 24 and 48 h (p < 0.05). Neutrophils degraded polymerized resin composite and produced higher amounts of bisHPPP than buffer after 48 h of incubation (p < 0.05). Neutrophils show generic MMP, gelatinase, MMP-2 and MMP-9, and collagenase, MMP-1 and MMP-8 activities that were stable or increased over the first 24 h (p < 0.05). Neutrophils degraded demineralized dentin more than buffer-only groups, indicated by higher amounts of hydroxyproline (p < 0.05). The ability of neutrophils to degrade both dental resin composite and tooth dentin, suggest neutrophil's potential role in root caries, and in recurrent carries by accelerating the degradation of resin-dentin interfaces, and compromising the longevity of the restoration. STATEMENT OF SIGNIFICANCE: Neutrophils are part of the innate immune system and are constantly entering the oral cavity through the gingival sulcus, in direct contact with the tooth, restoration, restoration-tooth margins and pathogenic bacteria. The current study is the first to characterize and quantify degradative activities from neutrophils toward methacrylate resin and demineralized dentin, the two main components of the restoration-tooth interface, suggesting that this interface could be negatively influenced by neutrophils, potentially contributing to increase in caries formation and progression, and premature restoration failure. This study provides a significant finding to the biomaterials and oral health fields by identifying a potential weakness in current restorative procedures and materials used to manage gingival proximal and cervical gingival or sub-gingival carious lesions.

Oral Neutrophils Characterized: Chemotactic, Phagocytic, and Neutrophil Extracellular Trap (NET) Formation Properties

Maintenance of oral health is in part managed by the immune-surveillance and antimicrobial functions of polymorphonuclear leukocytes (PMNs), which migrate from the circulatory system through the oral mucosal tissues as oral PMNs (oPMNs). In any microorganism-rich ecosystem, such as the oral cavity, PMNs migrate toward various exogenous chemoattractants, phagocytose bacteria, and produce neutrophil extracellular traps (NETs) to immobilize and eliminate pathogens. PMNs obtained from the circulation through venipuncture (hereafter called cPMNs) have been widely studied using various functional assays. We aimed to study the potential of oPMNs in maintaining oral health and therefore compared their chemotactic and antimicrobial functions with cPMNs. To establish chemotactic, phagocytic, and NET forming capacities, oPMNs and cPMNs were isolated from healthy subjects without obvious oral inflammation. Directional chemotaxis toward the chemoattractant fMLP was analyzed using an Insall chamber and video microscopy. fMLP expression was assessed by flow cytometry. Phagocytosis was analyzed by flow cytometry, following PMN incubation with heat-inactivated FITC-labeled micro-organisms. Furthermore, agar plate-based killing assays were performed with Escherichia coli (Ec). NET formation by oPMNs and cPMNs was quantified fluorimetrically using SYTOX™ Green, following stimulation with either PMA or RPMI medium (unstimulated control). In contrast to cPMNs, the chemotactic responses of oPMNs to fMLP did not differ from controls (mean velocity ± SEM of cPMNs: 0.79 ± 0.24; of oPMNs; 0.10 ± 0.07 micrometer/min). The impaired directional movement toward fMLP by oPMNs was explained by significantly lower fMLP receptor expression. Increased adhesion and internalization of various micro-organisms by oPMNs was observed. oPMNs formed 13 times more NETs than stimulated cPMNs, in both unstimulated and stimulated conditions. Compared to cPMNs, oPMNs showed a limited ability for intracellular killing of Ec. In conclusion, oPMNs showed exhausted capacity for efficient chemotaxis toward fMLP which may be the result of migration through the oral tissues into the oral cavity, being a highly “hostile” ecosystem. Overall, oPMNs' behavior is consistent with hyperactivity and frustrated killing. Nevertheless, oPMNs most likely contribute to maintaining a balanced oral ecosystem, as their ability to internalize microbes in conjunction with their abundant NET production remains after entering the oral cavity.

Exercise, Immunity, and Illness

It is generally accepted that moderate amounts of exercise improve immune system functions and hence reduce the risk of infection whereas athletes engaged in regular prolonged and/or intensive training have a higher than “normal” incidence of minor infections, especially of the upper respiratory tract (URT, e.g., common cold and influenza). This is likely related to regular acute (and possibly chronic) periods of exercise-induced changes in immune function. URT infections can compromise performance directly if suffered shortly before or during competition or indirectly if suffered at other times via effects on training and/or physiological adaptations. This chapter covers the effects of exercise (acute and chronic), both positive and negative, on immune function and consequent infection risk, and considers the current state-of-the-art for monitoring and assessing this in athletes.

Oral Polymorphonuclear Neutrophil Contributes to Oral Health

PURPOSE OF REVIEW

Oral health is maintained in a dynamic equilibrium between the host immunity and the oral microbiome. Oral polymorphonuclear neutrophils (oPMNs) are important innate immune cells in the oral cavity.

RECENT FINDINGS

The oPMNs play a co-controlling part in the maintenance of oral equilibrium. In human saliva, the oPMNs integrity is preserved, and their function remains unaffected. In general, oPMNs are in a higher state of baseline activation compared to peripheral PMNs. However, in periodontitis, the oPMNs' activation state can result in excessive release of damaging molecules in the extracellular environment.

SUMMARY

The presence of oPMNs may unwittingly negatively impact the integrity of the oral tissues. While most of the oPMN functions occur intracellularly, release of their potent active mediators into the extracellular environment may jeopardize oral homeostasis and its integrity. The dual nature of oPMNs, both beneficial and detrimental, remains a challenging and understudied topic.

Characterization of oral polymorphonuclear neutrophils in periodontitis patients: a case-control study

Background

Maintaining oral health is a continuous and dynamic process that also involves the immune system. Polymorphonuclear neutrophils (PMNs) migrate from blood circulation and become apparent in the oral fluid. Controversies exist regarding the specific role of the oral PMNs (oPMNs) in the presence of chronic oral inflammation, such as periodontitis. In this study we characterized cell counts, activation status, apoptosis, and reactive oxygen species (ROS) generation by oPMNs and circulatory (cPMNs), and the salivary protease activity, in subjects with and without periodontitis.

Methods

Venous blood and oral rinse samples were obtained from 19 patients with untreated periodontitis and 16 control subjects for PMN isolation. Apoptosis and expression of cell activation markers CD11b, CD63, and CD66b were analyzed using flow cytometry. Constitutive ROS generation was detected using dihydrorhodamine123. Additionally, ROS production in response to stimulation was evaluated in samples incubated with 10 μM phorbol myristate acetate (PMA) or Fusobacterium nucleatum. Total protease activity was measured using substrate PEK-054.

Results

Periodontitis patients presented with over 4 times higher oPMN counts compared to controls (p = 0.007), which was a predictor for the total protease activity (r² = 0.399, P = 0.007). More oPMNs were apoptotic in periodontitis patients compared to the controls (P = 0.004). All three activation markers were more expressed on the oPMNs compared to the cPMNs (p < 0.05), and a higher expression of CD11b on the oPMNs from periodontitis patients was observed compared to the control subjects (P = 0.024). Constitutive ROS production per oPMN was higher compared to the cPMN (P < 0.001). Additional analysis showed that the oPMNs retained their ability to respond to stimulation, with no apparent differences between the periodontitis and control subjects.

Conclusions

Higher numbers of oral PMNs, being more apoptotic and having increased levels of degranulation markers were found in periodontitis compared to periodontal health. However, since the oPMNs in periodontitis were responsive to ex vivo stimulation, we conclude that the oPMNs are active in the oral ecosystem. It is currently unknown whether the oPMN counts, which correlated with the detected protease levels, are detrimental in the long term for the oral mucosa integrity.

Trial registration

This study was retrospectively registered at the ISRCTN registry (trial ID ISRCTN15252886). Registration date August 11, 2017.

Eosinophil cationic protein and histamine production by neutrophils from patients with periodontitis

BACKGROUND

Periodontitis develops through an inflammatory process caused by an infection at the microbial biofilm, followed by tissue destruction mediated by leukocytes, which cause clinically significant destruction of connective tissue and bone. Several elements derived from the bacteria cause the inflammatory response and the release of mediators involved in destruction of the periodontium. There are number of inflammatory mediators released by leukocytes, mainly neutrophils, upon bacterial challenge. Neutrophils produce and release eosinophil cationic protein (ECP) and histamine, two important inflammatory mediators; however, their role has not been characterized in periodontal inflammation. Thus, the purpose of this study is to investigate whether neutrophils from patients with periodontitis can produce ECP and histamine in response to lipopolysaccharides (LPSs).

METHODS

ECP and histamine production in response to LPSs was analyzed by enzyme-linked immunosorbent assay. Expression of the histidine decarboxylase and ECP was also analyzed by flow cytometry and fluorescence microscopy in neutrophils from patients with periodontitis in response to LPS.

RESULTS

It was found that neutrophils from patients with periodontitis express higher levels of histidine decarboxylase and ECP than those from healthy volunteers, and they also release higher levels of histamine.

CONCLUSION

Findings described could represent new knowledge indicating neutrophils as a source of histamine and ECP in the progression of periodontitis.

Investigation of a Novel Predictive Biomarker Profile for the Outcome of Periodontal Treatment

BACKGROUND

An ability to predict the response to conventional non-surgical treatment of a periodontal site would be advantageous. However, biomarkers or tests devised to achieve this have lacked sensitivity. The aim of this study is to assess the ability of a novel combination of biomarkers to predict treatment outcome of patients with chronic periodontitis.

METHODS

Gingival crevicular fluid (GCF) and subgingival plaque were collected from 77 patients at three representative sites, one healthy (probing depth [PD] ≤3 mm) and two diseased (PD ≥6 mm), at baseline and at 3 and 6 months after treatment. Patients received standard non-surgical periodontal treatment at each time point as appropriate. The outcome measure was improvement in probing depth of ≥2 mm. Concentrations of active enzymes (matrix metalloproteinase [MMP]-8, elastase, and sialidase) in GCF and subgingival plaque levels of Porphyromonas gingivalis, Tannerella forsythia, and Fusobacterium nucleatum were analyzed for prediction of the outcome measure.

RESULTS

Using threshold values of MMP-8 (94 ng/μL), elastase (33 ng/μL), sialidase (23 ng/μL), and levels of P. gingivalis (0.23%) and T. forsythia (0.35%), receiver operating characteristic curves analysis demonstrated that these biomarkers at baseline could differentiate healthy from diseased sites (sensitivity and specificity ≥77%). Furthermore, logistic regression showed that this combination of these biomarkers at baseline provided accurate predictions of treatment outcome (≥92%).

CONCLUSION

The "fingerprint" of GCF enzymes and bacteria described here offers a way to predict the outcome of non-surgical periodontal treatment on a site-specific basis.

Manipulation of Neutrophils by Porphyromonas gingivalis in the Development of Periodontitis

The pathogenesis of the chronic periodontal disease is associated with a skewed host inflammatory response to periodontal pathogens, such as Porphyromonas gingivalis, that accounts for the majority of periodontal tissue damage. Neutrophils are the most abundant leukocytes in periodontal pockets and depending on the stage of the disease, also plentiful PMNs are present in the inflamed gingival tissue and the gingival crevice. They are the most efficient phagocytes and eliminate pathogens by a variety of means, which are either oxygen-dependent or -independent. However, these secretory lethal weapons do not strictly discriminate between pathogens and host tissue. Current studies describe conflicting findings about neutrophil involvement in periodontal disease. On one hand literature indicate that hyper-reactive neutrophils are the main immune cell type responsible for this observed tissue damage and disease progression. Deregulation of neutrophil survival and functions, such as chemotaxis, migration, secretion of antimicrobial peptides or enzymes, and production of reactive oxygen species, contribute to observed tissue injury and the clinical signs of periodontal disease. On the other hand neutrophils deficiencies in patients and mice also result in periodontal phenotype. Therefore, P. gingivalis represents a periodontal pathogen that manipulates the immune responses of PMNs, employing several virulence factors, such as gingipains, serine proteases, lipid phosphatases, or fimbriae. This review will sum up studies devoted to understanding different strategies utilized by P. gingivalis to manipulate PMNs survival and functions in order to inhibit killing by a granular content, prolong inflammation, and gain access to nutrient resources.

Oral polymorphonuclear neutrophil characteristics in relation to oral health: a cross-sectional, observational clinical study

Polymorphonuclear neutrophils (PMNs) have a major role in the innate immune system. However, little is known about PMN contribution in relation to oral health. The objective of this study was to investigate the numbers and functional characteristics of oral PMNs (oPMNs) compared with circulatory PMNs (cPMNs). Oral rinse and venous blood samples were obtained from 268 systemically and orally healthy volunteers in a cross-sectional observational study. PMN counts, cell cycle analysis and cellular activation state were investigated. Also, reactive oxygen species (ROS) production was analyzed, with and without bacterial stimulation (Fusobacterium nucleatum). In males, 1.2 × 10⁶±1.0 × 10⁶ oPMNs were collected, and showed a tendency to correlate with the levels of gingival bleeding (r=0.215, P=0.008). Comparable oPMNs counts were found among females (1.0 × 10⁶±0.7 × 10⁶). More late-stage apoptotic/necrotic cells were found among the oPMNs (53.1%) compared with the cPMNs (8.5% P<0.001). Without additional stimulation, oPMNs were more activated than cPMNs, as indicated by higher expression of CD11b, CD63 and CD66b, and higher constitutive ROS levels (P<0.001). Notably, in response to bacterial stimulation, oPMNs released comparable ROS levels as cPMNs (P=0.042). In conclusion, this study provides data on viable oPMNs showing high levels of activation in orally and systemically healthy individuals, free of apparent caries lesions and periodontal disease. These data suggests that although the oPMNs are in a more mature stage of their life cycle compared with the cPMNs, oPMNs are still responsive to stimulation, which indicates their functional potential and possible contribution to a healthy oral ecosystem.

Distinct Oral Neutrophil Subsets Define Health and Periodontal Disease States

Neutrophils exit the vasculature and swarm to sites of inflammation and infection. However, these cells are abundant in the healthy, inflammation-free human oral environment, suggesting a unique immune surveillance role within the periodontium. We hypothesize that neutrophils in the healthy oral cavity occur in an intermediary parainflammatory state that allows them to interact with and contain the oral microflora without eliciting a marked inflammatory response. Based on a high-throughput screen of neutrophil CD (cluster of differentiation) marker expression and a thorough literature review, we developed multicolor flow cytometry panels to determine the surface marker signatures of oral neutrophil subsets in periodontal health and disease. We define here 3 distinct neutrophil subsets: resting/naive circulatory neutrophils, parainflammatory neutrophils found in the healthy oral cavity, and proinflammatory neutrophils found in the oral cavity during chronic periodontal disease. Furthermore, parainflammatory neutrophils manifest as 2 distinct subpopulations-based on size, granularity, and expression of specific CD markers-and exhibit intermediate levels of activation as compared with the proinflammatory oral neutrophils. These intermediately activated parainflammatory populations occur in equal proportions in the healthy oral cavity, with a shift to one highly activated proinflammatory neutrophil population in chronic periodontal disease. This work is the first to identify and characterize oral parainflammatory neutrophils that interact with commensal biofilms without inducing an inflammatory response, thereby demonstrating that not all neutrophils trafficking through periodontal tissues are fully activated. In addition to establishing possible diagnostic and treatment monitoring biomarkers, this oral neutrophil phenotype model builds on existing literature suggesting that the healthy periodontium may be in a parainflammatory state.

Nuclear Factor Erythroid 2-Related Factor 2 Down-Regulation in Oral Neutrophils Is Associated with Periodontal Oxidative Damage and Severe Chronic Periodontitis

The balance between reactive oxygen species and antioxidants plays an important role in periodontal health. We previously demonstrated that high reactive oxygen species production by oral polymorphonuclear neutrophils (oPMNs) in chronic periodontitis (CP) refractory to conventional therapy is associated with severe destruction of periodontium. Herein, we show that inhibition of antioxidant production through down-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in oPMN, despite enhanced recruitment in the oral cavity, is associated with severe CP. Twenty-four genes in the Nrf2-mediated oxidative stress response pathway were down-regulated in PMNs of diseased patients. Downstream of Nrf2, levels of oPMN superoxide dismutase 1 and catalase were decreased in severe CP, despite increased recruitment. Nrf2(-/-) mice had more severe loss of periodontium in response to periodontitis-inducing subgingival ligatures compared with wild-types. Levels of 8-hydroxy-deoxyguanosine were increased in periodontal lesions of Nrf2(-/-) mice, indicating high oxidative damage. We report, for the first time, Nrf2 pathway down-regulation in oPMNs of patients with severe CP. PMNs of CP patients may be primed for low antioxidant response in the context of high recruitment in the oral cavity, resulting in increased oxidative tissue damage.

Identification of neutrophil surface marker changes in health and inflammation using high-throughput screening flow cytometry

Neutrophils are the most abundant white blood cell and are an essential component of the innate immune system. A complete cataloguing of cell surface markers has not been undertaken for neutrophils isolated from circulation as well as healthy and inflamed tissues. To identify cell-surface markers specific to human neutrophils, we used high-throughput flow cytometry to screen neutrophil populations isolated from blood and oral rinses from healthy and chronic periodontitis patients against a panel of 374 known cluster of differentiation (CD) antibodies. This screen identified CD11b, CD16, and CD66b as markers that are consistently expressed on neutrophils independent of the cell location, level of activation and disease state. Cell sorting against CD11b, CD16 and CD66b allowed for the enrichment of mature neutrophils, yielding neutrophil populations with up to 99% purity. These findings suggest an ideal surface marker set for isolating mature neutrophils from humans. The screen also demonstrated that tissue neutrophils from chronically inflamed tissue display a unique surface marker set compared to tissue neutrophils present in healthy, non-inflamed tissues.

Factors Influencing Adoption of New Technologies into Dental Practice: A Qualitative Study

The objective of this study was to explore factors affecting decisions to adopt new technologies into dental practice using a colorimetric rinse test for detection of periodontal disease as a model. Focus groups with key informants in Canadian dentistry and dental hygiene were conducted. A deductive approach used Rogers's diffusion of innovation theory as a framework for organizing codes and subcodes. Two members of the research team independently reviewed and analyzed the data using NVivo 10. The attributes of the technology itself emerged as primary influencers. Perceived relative advantages of the diagnostic mouth rinse over existing methods were potential time efficiency, low implementation cost, and utility of the tool. Low complexity, compatibility with existing routines/beliefs, and the potential for reinvention-the use of a technology for other than its intended purpose (i.e., patient education, monitoring of disease, screening tool in nondental settings)-were other important features enhancing adoption. An overarching concern was that any new technology benefit the patient. Contextual factors also play a role. Numerous communication channels, including opinion leaders, patients, marketing, continuing education courses, and strength of evidence, influenced clinicians, with peer interaction being a stronger influence than marketing. Similar themes arose from specialist, general dentist, and dental hygienist focus groups. Adopter characteristics also came into play: participants ranged in their self-reported innovativeness with many considering themselves "early adopters" of new technology. Findings of this study suggest that the innovation adoption process is not straightforward, but attributes of the innovation, contextual factors, and adopter characteristics play important roles in the process. Knowledge Transfer Statement: Various factors affect the adoption of new tools into clinical dental practice. These include attributes of the test or tool itself, the context of the settings in which the tool is introduced to practitioners, and the characteristics of the clinicians themselves. A qualitative study of dentists and dental hygienists investigated these factors. Situations in which dentists and hygienists interact with their peers and colleagues-through social networks, continuing education courses, conventions, or personal contact-were a major driver in the decision to adopt new technologies. However, even among "early adopters," most were reluctant to use new tests or tools unless they perceived a benefit to their patients or practice.

Efficacy of Combined Photoablative-Photodynamic Diode Laser Therapy Adjunctive to Scaling and Root Planing in Periodontitis: Randomized Split-Mouth Trial with 4-Year Follow-Up

OBJECTIVE

We previously showed that photoablative laser therapy followed by multiple photodynamic cycles (PAPD) after scaling/root planing (SRP) improved healing of periodontitis patients as compared with conventional SRP after 1-year follow-up. This study reports the favorable results of PAPD plus SRP in patients with chronic periodontitis at a 4-year follow-up.

MATERIALS AND METHODS

Twenty-four patients were studied. Maxillary left or right quadrants were randomly assigned to PAPD laser treatment or sham-treatment and SRP. PAPD consisted of: (1) photoablative intra/extrapocket de-epithelization with diode laser (λ 810 nm, 1 W), and (2) photodynamic treatments (4-10 weekly) with diode laser (λ 635 nm, 100 mW) and 0.3% methylene blue as photoactive antiseptic, performed after SRP. Sham treatment was performed with switched- off laser. Probing depth (PD), clinical attachment level (CAL), and bleeding-on-probing (BOP) were evaluated. Additional disease markers, namely polymorphonuclear leukocytes (PMN), erythrocytes (RBC), damaged epithelial cells (DEC), and bacteria were assayed by cytofluorescence on gingival exfoliative samples.

RESULTS

At 4-year follow-up, PAPD plus SRP significantly improved PD, CAL, and BOP, as well as bacterial contamination and PMN-RBC shedding in the exfoliative samples, compared with sham treatment plus SRP. This effect was greater than that observed at 1-year follow-up.

CONCLUSIONS

PAPD plus SRP provided significant, durable improvement of chronic periodontitis over sham treatment plus SRP alone.

Oral neutrophils are an independent marker of the systemic inflammatory response after cardiac bypass

Background

Cardiopulmonary bypass (CPB) is an immuno-reactive state where neutrophils are activated and accumulate in different tissues. Edema and tissue necrosis are the most common sequelae observed, predominantly in the lungs, kidneys, and heart, heralding significant risk for postoperative complications. No method exists to noninvasively assess in vivo neutrophil activity. The objective of this study was to determine if neutrophil recruitment to the oral cavity would correlate with specific biomarkers after coronary bypass surgery (CPB).

Methods

We conducted a single site prospective observational study including non-consecutive adult patients undergoing elective, on-pump CPB. Blood and either oral cavity rinses or swabs were collected pre- and post-CPB. Absolute neutrophil counts from oral samples and serum biomarkers were measured. The association between neutrophil recruitment to the oral cavity, biomarkers and outcomes after CPB were analyzed.

Results

CPB was associated with statistically significant increases in oral and blood neutrophil counts, as well as an increase in certain biomarkers over preoperative baseline. Peripheral blood neutrophil count were increased at all time points however statistically significant differences in median oral neutrophil counts were observed only at the time point immediately postoperative, and in what seems to be two unique patient populations (p < 0.001; group 1, median: 1.6×10⁵, Interquartile range [IQR], 1.1×10⁵ - 4.8×10⁵, and group 2, median: 1.9×10⁶, IQR, 8.7×10⁵ - 4.0×10⁶).

Conclusions

CPB is associated with a transient increase in oral neutrophils that may correlate with the systemic inflammatory response; oral neutrophils may have the ability to discriminate and identify unique patient populations based on their tissue migration.

Quantifying oral inflammatory load: oral neutrophil counts in periodontal health and disease

BACKGROUND AND OBJECTIVE

Neutrophils are the primary white blood cells that are recruited to fight the initial phases of microbial infections. While healthy norms have been determined for circulating blood neutrophil counts in order to identify patients with suspected systemic infections, the levels of oral neutrophils (oPMNs) in oral health and in the presence of periodontal diseases have not been described. It is important to address this deficiency in our knowledge as neutrophils are the primary immune cell present in the crevicular fluid and oral environment and previous work has suggested that they may be good indicators of overall oral inflammation and periodontal disease severity. The objective of this study was to measure oPMN counts obtained in a standardized oral rinse from healthy patients and from those with chronic periodontal disease in order to determine if oPMN levels have clinical relevance as markers of periodontal inflammation. A parallel goal of this investigation was to introduce the concept of 'oral inflammatory load', which constitutes the inflammatory burden experienced by the body as a consequence of oral inflammatory disease.

MATERIAL AND METHODS

Periodontal examinations of patients with a healthy periodontium and chronic periodontal disease were performed (n = 124). Two standardized consecutive saline rinses of 30 s each were collected before patient examination and instrumentation. Neutrophils were quantified in the rinse samples and correlated with the clinical parameters and periodontal diagnosis.

RESULTS

Average oPMN counts were determined for healthy patients and for those with mild, moderate and severe chronic periodontal diseases. A statistically significant correlation was found between oPMN counts and deep periodontal probing, sites with bleeding on probing and overall severity of periodontal disease.

CONCLUSIONS

oPMN counts obtained through a 30-s oral rinse are a good marker of oral inflammatory load and correlate with measures of periodontal disease severity.