Substance P and neurokinin A in gingival crevicular fluid in periodontal health and disease

Association of periodontitis and periodontal parameters with migraine and mortality in people with migraine disease: A nationally representative observational study

OBJECTIVE

To investigate the association of periodontitis and clinical periodontal parameters with migraine as well as mortality among people with migraine disease.

BACKGROUND

Periodontitis has been shown to increase the systemic inflammatory burden thereby promoting various systemic health outcomes; however, the evidence regarding the relationship between periodontitis and migraine is scarce.

METHODS

A cross-sectional study was performed, and it included 13,108 participants from the National Health and Nutrition Examination Survey (1999-2004). Weighted logistic regression analysis was used to evaluate the association between periodontitis/clinical periodontal parameters and migraine. Mediation analysis was performed to explore the potential mediating role of inflammatory response. A cohort study including 1909 participants with migraine disease was further conducted to assess the associations between periodontitis/clinical periodontal parameters and mortality from all causes, cardiovascular disease (CVD), and cancer in participants with migraine disease using Cox proportional hazards models. Death outcomes were ascertained by linkage to National Death Index records through December 31, 2018.

RESULTS

Periodontitis was positively associated with migraine (odds ratio [OR] 1.29, 95% confidence interval [CI] 1.01-1.65). Each 1-unit rise in attachment loss and pocket depth was linked to a 17.5% (OR 1.18, 95% CI 1.08-1.29) and 28.1% (OR 1.28, 95% CI 1.08-1.51) increase in migraine risk, respectively. Mediation analyses revealed that leukocyte, monocyte, and lymphocyte counts mediated 17.9%, 7.3%, and 20.1%, respectively, of the association between periodontitis and migraine. During a median follow-up of 17.7 years among 1909 participants with migraine disease, periodontitis was associated with greater all-cause mortality (hazard ratio 1.82, 95% CI 1.25-2.66), but was not significantly associated with mortality from CVD or cancer among participants with migraine disease. Similar association patterns were also observed for attachment loss and pocket depth.

CONCLUSIONS

This study provides evidence that periodontitis and clinical periodontal parameters were significantly associated with migraine as well as all-cause mortality in people with migraine disease. These findings underscore the importance of considering periodontal health in the prevention and management strategies for migraine disease.

Periodontitis increases the risk of gastrointestinal dysfunction: an update on the plausible pathogenic molecular mechanisms

Periodontitis is an immuno-inflammatory disease of the soft tissues surrounding the teeth. Periodontitis is linked to many communicable and non-communicable diseases such as diabetes, cardiovascular disease, rheumatoid arthritis, and cancers. The oral-systemic link between periodontal disease and systemic diseases is attributed to the spread of inflammation, microbial products and microbes to distant organ systems. Oral bacteria reach the gut via swallowed saliva, whereby they induce gut dysbiosis and gastrointestinal dysfunctions. Some periodontal pathogens like Porphyromonas. gingivalis, Klebsiella, Helicobacter. Pylori, Streptococcus, Veillonella, Parvimonas micra, Fusobacterium nucleatum, Peptostreptococcus, Haemophilus, Aggregatibacter actinomycetomcommitans and Streptococcus mutans can withstand the unfavorable acidic, survive in the gut and result in gut dysbiosis. Gut dysbiosis increases gut inflammation, and induce dysplastic changes that lead to gut dysfunction. Various studies have linked oral bacteria, and oral-gut axis to various GIT disorders like inflammatory bowel disease, liver diseases, hepatocellular and pancreatic ductal carcinoma, ulcerative colitis, and Crohn's disease. Although the correlation between periodontitis and GIT disorders is well established, the intricate molecular mechanisms by which oral microflora induce these changes have not been discussed extensively. This review comprehensively discusses the intricate and unique molecular and immunological mechanisms by which periodontal pathogens can induce gut dysbiosis and dysfunction.

Nociceptor-Macrophage Interactions in Apical Periodontitis: How Biomolecules Link Inflammation with Pain

Periradicular tissues have a rich supply of peripheral afferent neurons, also known as nociceptive neurons, originating from the trigeminal nerve. While their primary function is to relay pain signals to the brain, these are known to be involved in modulating innate and adaptive immunity by initiating neurogenic inflammation (NI). Studies have investigated neuroanatomy and measured the levels of biomolecules such as cytokines and neuropeptides in human saliva, gingival crevicular fluid, or blood/serum samples in apical periodontitis (AP) to validate the possible role of trigeminal nociceptors in inflammation and tissue regeneration. However, the contributions of nociceptors and the mechanisms involved in the neuro-immune interactions in AP are not fully understood. This narrative review addresses the complex biomolecular interactions of trigeminal nociceptors with macrophages, the effector cells of the innate immune system, in the clinical manifestations of AP.

Gingival Crevicular Fluid Levels of Neurokinin A and Substance P in Patients with Symptomatic Irreversible Pulpitis: A Systematic Review and Meta-Analysis

Aims and Objectives

The levels of neuropeptides neurokinin A (NKA) and substance P (SP) in the gingival crevicular fluid of patients with symptomatic irreversible pulpitis (SIP) were evaluated using a comprehensive review and meta-analysis.

Materials and Methods

The data bases of Pubmed, Scopus, EBSCOhost, Science Direct, Proquest and Cochrane library databases were thoroughly searched. The quality of the study was evaluated using the Joanna Briggs Criteria. Twenty four studies were listed following a thorough search of full texts, abstracts, and removal of duplicates. Only two of these papers were eligible for inclusion in the meta-analysis. Since the results obtained were in mean and standard deviation, the levels of neuropeptides in the test and control groups were examined using the meta-analysis.

Results

When compared with healthy teeth, NKA was not significantly elevated in GCF of individuals with SIP (P = 0.06; odd ratio = 1.34 [-0.05 to 2.74] at 95% confidence interval [CI]). Additionally, there was no evidence of an association between SP and SIP (P = 0.08; odds ratio = 0.84 [-0.10 to 1.77] at 95% CI).

Conclusion

This systematic research demonstrated that in individuals with SIP, NKA, and SP are not substantially linked. However, the lack of study in this area makes it evident that additional research is needed, particularly in relation to pulpal disorders and NKA.

Substance P aggravates ligature-induced periodontitis in mice

Periodontitis is one of the most common oral diseases in humans, affecting over 40% of adult Americans. Pain-sensing nerves, or nociceptors, sense local environmental changes and often contain neuropeptides. Recent studies have suggested that nociceptors magnify host response and regulate bone loss in the periodontium. A subset of nociceptors projected to periodontium contains neuropeptides, such as calcitonin gene-related peptide (CGRP) or substance P (SP). However, the specific roles of neuropeptides from nociceptive neural terminals in periodontitis remain to be determined. In this study, we investigated the roles of neuropeptides on host responses and bone loss in ligature-induced periodontitis. Deletion of tachykinin precursor 1 (Tac1), a gene that encodes SP, or treatment of gingiva with SP antagonist significantly reduced bone loss in ligature-induced periodontitis, whereas deletion of calcitonin related polypeptide alpha (Calca), a gene that encodes CGRP, showed a marginal role on bone loss. Ligature-induced recruitment of leukocytes, including neutrophils, and increase in cytokines leading to bone loss in periodontium was significantly less in Tac1 knockout mice. Furthermore, intra-gingival injection of SP, but not neurokinin A, induced a vigorous inflammatory response and osteoclast activation in alveolar bone and facilitated bone loss in ligature-induced periodontitis. Altogether, our data suggest that SP plays significant roles in regulating host responses and bone resorption in ligature-induced periodontitis.

Establishing the Role of Neurogenic Inflammation in the Pathogenesis of Periodontitis: A Systematic Review

The role of neurogenic inflammation in various systemic diseases has been well established, but there is a dearth of studies and evidence regarding its role in periodontitis. This study aimed to systematically review the evidence in establishing the role of neurogenic inflammation in chronic periodontitis. Databases such as PubMed, Scopus, and Google Scholar were reviewed. We analyzed studies of any design that compared and evaluated the presence of neuropeptides such as substance P, calcitonin gene-related peptide, neurokinin A, neuropeptide Y, and vasoactive intestinal polypeptide in systemically healthy patients with and without periodontitis. We screened 2,495 articles and abstracts electronically and manually, which yielded 191 articles relevant to our study. Full-text examination of these 191 articles led to the final inclusion of 14 publications. Most studies here confirmed an association between various neuropeptides and periodontitis, but there is a high heterogeneity between the studies, making it necessary to clarify the mechanism between these two. Although most studies included in this review found a positive association between neurogenic inflammation and periodontitis, the evidence is of moderate to low quality.

A Mini Review: The Potential Biomarkers for Non-invasive Diagnosis of Pulpal Inflammation

For assessing the adequacy of vital pulp therapy for an inflamed pulp, the use of non-invasive diagnostic tools is necessary to avoid further damage to the teeth. Detection of biomarkers that are indicative of the inflammatory status in pulp can be a promising tool for this purpose. These biomarkers need to be reliably correlated with pulpal inflammation and to be easily detected without pulp exposure. This mini-review article aims to review biomarkers that are present in gingival crevicular fluid (GCF) in inflamed pulp conditions. Several studies have reported the availability of various biomarkers including cytokines, proteases, elastase, neuropeptides, and growth factors. Non-invasive pulpal diagnostic methods will be useful as well to determine reversibility, irreversibility, or necrosis of inflamed pulp. These types of molecular diagnoses via analyzing the proteome have revolutionized the medical field, and are one of the most promising empirical methodologies that a clinician can utilize for the proactive identification of pulpal disease.

Differential regulation of NPY and SP receptor expression in STRO-1+ve PDLSCs by inflammatory cytokines

OBJECTIVES

The aims of this study were to investigate neuropeptide receptor expression regulation on STRO-1 +ve periodontal ligament stem cells (PDLSCs) in response to inflammatory cytokines and to investigate a potential osteogenic effect of neuropeptides.

BACKGROUND

Nerve fibres innervating the periodontal tissues in humans contain several neuropeptides including neuropeptide Y and substance P. The role of neuropeptide receptors on PDLSCs, including their response to the local inflammatory environment of periodontitis, is currently unknown.

METHODS

A homogenous population of STRO-1 +ve PDLSCs was prepared by immunomagnetic separation of cells obtained by the tissue out-growth method from healthy premolar teeth from a single donor. Regulation of gene expression of the neuropeptide Y Y1 receptor and substance P receptor tachykinin receptor 1 was investigated. A potential osteogenic effect of neuropeptide Y and substance P was also investigated by measuring alkaline phosphatase (ALP) activity, Alizarin red staining and quantifying osteogenic gene expression.

RESULTS

Treatment of STRO-1 +ve PDLSCs with tumour necrosis factor-alpha or interleukin 1-beta up-regulated the expression of the neuropeptide Y's Y1 receptor, but down-regulated substance P's receptor. Significantly increased ALP activity was observed in STRO-1 +ve PDLSCs treated with neuropeptide Y but not substance P. Further studies showed that neuropeptide Y had a modest osteogenic effect on cells at both a functional level and a gene level.

CONCLUSIONS

Expression of the neuropeptide Y Y1 receptor gene on STRO-1 +ve PDLSCs was sensitive to local inflammatory cytokines. Treatment of cells with neuropeptide Y was found to produce a modest enhanced osteogenic effect.

Application of weighted gene co-expression network analysis to reveal key modules and hub genes in generalized aggressive periodontitis

OBJECTIVE

The aim of this study was to construct a gene co-expression network to identify key modules and genes in people with generalized aggressive periodontitis.

METHODS

We used database GSE79705 to construct a co-expression network by weighted gene co-expression network analysis (WGCNA). In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted.

RESULTS

A total of 51 co-expression modules were conducted, darkseagreen1 and blue1 modules were the most significantly related to generalized aggressive periodontitis. Genes in the darkseagreen1 module enriched in affecting cellular response to tumor necrosis factor and vascular endothelial growth factor production, and the blue1 module enriched in the regulation of ion transport, proteinaceous extracellular matrix and neuropeptide binding. Besides, we found that 4 hub genes (SNRPG, MRPL22, MRPS18C and CEP290) played an important role in the occurrence of generalized aggressive periodontitis.

CONCLUSION

Through this study, we identified two modules and four hub genes associated with generalized aggressive periodontitis. Besides, 4 hub genes (SNRPG, MRPL22, MRPS18C and CEP290) can be expected to trigger new therapeutic drug development for generalized aggressive periodontitis.

Substance P participates in periodontitis by upregulating HIF-1α and RANKL/OPG ratio

BACKGROUND

Both substance P and hypoxia-inducible factor 1 alpha (HIF-1α) are involved in inflammation and angiogenesis. However, the relationship between substance P and HIF-1α in rat periodontitis is still unknown.

METHODS

Ligation-induced rat periodontitis was established to observe the distribution and expression of substance P and HIF-1α by immunohistochemistry. Rat gingival fibroblasts were cultured and stimulated with Porphyromonas gingivalis lipopolysaccharide (LPS). Recombinant substance P was applied to elaborate the relationship between substance P and HIF-1α in gingival fibroblasts in vitro. Primary mouse bone marrow-derived macrophages (BMMs) were isolated and cultured to observe the effect of substance P on receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis by TRAP staining. Western blotting was used to investigate the expression of HIF-1α, osteoprotegerin (OPG) and RANKL.

RESULTS

Rat experimental periodontitis was successfully established 6 weeks after ligation. Gingival inflammatory infiltration and alveolar bone loss were observed. Positive expression of substance P was found in the infiltrating cells. Higher HIF-1α levels were observed in periodontitis compared to that of normal tissues. Substance P upregulated the level of HIF-1α in gingival fibroblasts with or without 1 μg/ml LPS in vitro (*P < 0.05). Substance P upregulated the expression of HIF-1α in RANKL-stimulated BMMs in vitro. Substance P also increased the RANKL/OPG ratio in gingival fibroblasts (*P < 0.05). Both 10 nM and 50 nM substance P promoted RANKL-induced osteoclast differentiation (*P < 0.05).

CONCLUSION

Substance P participates in periodontitis by upregulating HIF-1α and the RANKL/OPG ratio.

Self-reported periodontitis and migraine: results from a multicenter, cross-sectional survey in Spain

The aim of this study was to evaluate self-reported periodontitis (PD) prevalence in migraineurs as well as to investigate the association between both diseases. A cross-sectional survey was carried out including patients diagnosed with migraine attending 12 Spanish Headache Units. We determined diagnosis of PD administering a validated self-reported questionnaire. Socio-demographic, clinical and medical information, comorbidities, daily habits, migraine characteristics and medication were collected using a questionnaire. Of the 651 consecutive migraineurs included in the study, 393 suffered from chronic migraine (CM). Self-reported PD was detected in 327 patients with migraine (50.2%). Migraineurs with self-reported PD were significantly older and had a previous history of fibromyalgia, stress, anxiety, depression, and allodynia (all P < 0.001). Additionally, this group of patients consumed more topiramate (P = 0.008) and simple analgesics (P < 0.001) than patients with migraine and without self-reported PD. Also, they were less active physically and belonged to a low education level (both P < 0.001). Prevalence of self-reported PD was significantly higher in chronic migraineurs compared to those diagnosed with episodic migraine (EM) (53.9% vs. 44.6%, P = 0.019). Logistic regression analyses showed that self-reported PD was associated with CM (OR 1.456; 95% CI 1.062-1.997, P = 0.020). However, after adjusting for significant confounders, the association was attenuated (OR 1.100; 95% CI 0.784-1.543, P = 0.581). We concluded that self-reported PD was significantly more frequent in CM compared to EM. Self-reported PD was associated with the presence of CM, although some comorbidities shared by both diseases could have an effect on this association.

Gene expression analysis of neuropeptides in oral mucosa during periodontal disease in non-human primates

BACKGROUND

Neuropeptides (NPs) are innate pivotal regulators of the immunoinflammatory response. Nevertheless, their role in the pathogenesis of periodontal disease remains unknown. Changes in gene expression of 10 NPs and 16 NP receptors (NPRs) coincident with the initiation, progression, and resolution of periodontitis were determined.

METHODS

The ligature-induced periodontitis model was used in rhesus monkeys (n = 18). Gingival tissue samples were taken at baseline (preligatures), at 2 weeks and at 1 month (initiation), and at 3 months (progression) postligation. Ligatures were removed and samples taken 2 months later (resolution). Total RNA was isolated from tissues and NP/NPR gene expression microarray analysis was performed. Gene expression changes were validated by quantitative polymerase chain reaction and immunohistochemistry.

RESULTS

Unexpectedly, the expression of pro-inflammatory NPs/NPRs did not change during periodontitis or with resolution. However, increased expression of the anti-inflammatory NPs adrenomedullin (ADM) and galanin (GAL), and the NPRs calcitonin receptor-like (CALCRL) and receptor activity-modifying protein-2 and -3 (RAMP2 and RAMP3) were observed during initiation and progression of disease. The expression of the same NPs/NPRs exhibited a significant positive correlation with both molecular (interleukin-1ß, matrix mettaloproteinase-9, and receptor activator of nuclear factor-kappa B ligand) and clinical measures of gingival inflammation and tissue destruction.

CONCLUSION

Initiation and progression of periodontitis involve significant overexpression of ADM, GAL, CALCRL, RAMP2, and RAMP3. These anti-inflammatory NPs/NPRs could play a role in the unresolved infection and inflammation that normally drives tissue destruction in periodontitis. Both ADM and GAL potentially are new candidates to consider as biomolecules associated with periodontal disease activity.

Salivary neuropeptides, stress, and periodontitis

BACKGROUND

Scientific evidence for psychologic stress as a risk factor for periodontitis is fragmentary and relies mostly on either questionnaire-based or biomarker studies. The aim of this study is to investigate brain-derived neurotrophic factor, substance P, vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), calcitonin gene-related peptide, and adrenomedullin as well as cortisol in saliva and serum in periodontal health and disease combined with different aspects of stress and possible associations with clinical parameters.

METHODS

In total, 56 patients with aggressive and chronic periodontitis and 44 healthy controls were screened by enzyme-linked immunosorbent assay and mass spectrometry for presence of neuropeptides and cortisol in saliva and serum. Psychologic stress was evaluated by validated questionnaires. All substances were explored for a possible relationship to periodontitis, clinical parameters, and stress.

RESULTS

VIP and NPY showed significantly higher levels in saliva but not in serum of patients with periodontitis. These neuropeptides correlated with the extent, severity, and bleeding on probing scores in patients with periodontitis. Females had significantly lower salivary VIP levels. There were no differences among participants regarding psychologic stress.

CONCLUSION

VIP and NPY in saliva could be potential sex-specific salivary biomarkers for periodontitis regardless of psychologic stress.

Periodontal disease as a potential factor of migraine chronification

Migraine is a hereditary constitutional base disorder, which is characterized by recurrent episodes of headache pulsatile characteristics associated with photophobia/phonophobia, nausea and/or vomiting. The main complication in migraine is the chronicity of the process, now recognized as a chronic migraine. Although pathogenic mechanisms that may influence the pathophysiology of migraine and its possible chronicity are not fully understood, previous studies have shown in patients with migraine molecular alterations of systemic inflammation, neurogenic inflammation, endothelial dysfunction, innate immunity, dysfunction of matrix proteases and blood-brain barrier. Periodontal disease is an inflammatory lesion caused by bacteria. After the bacterial infection begins, an immune response that will be responsible for individual susceptibility appears. More advanced forms of periodontitis have demonstrated molecular alterations of inflammation, endothelial dysfunction, dysfunction of matrix proteases and innate immunity, similar to those observed in migraine. Furthermore, the main molecular mediators of neurogenic inflammation related to activation of the trigeminovascular system, which are characteristic of migraine, are overexpressed in gingival crevicular fluid and mucosa in patients with periodontal disease. Hypertension, hypercholesterolemia, insulin resistance, stroke or coronary artery disease are comorbidities that periodontal disease and migraine could share. Therefore, several mechanisms and hypotheses could explain the possible association between both diseases. However, epidemiological and molecular studies will be necessary to provide a better understanding of this potential association, which could be implicated in the chronification of migraine.

Comparative study of substance P and neurokinin A in gingival crevicular fluid of healthy and painful carious permanent teeth

BACKGROUND

It is shown that neuropeptides can be transported from pulp chamber to periodontal ligament through apical foramen and accessory canals. Therefore, clinical pulpal pain leads to expression of preinflammatory neuropeptides such as substance P (SP) and neurokinin A (NKA) in gingival crevicular fluid (GCF). This study aimed to evaluate levels of SP and NKA in GCF of carious and healthy permanent teeth, comparatively.

MATERIALS AND METHODS

This cross-sectional study was performed on twenty children referred to Department of Pediatric Dentistry, Tehran University of Medical Sciences, who had a painful permanent first molar. Sampling was done by sterile paper cone from GCF of the mentioned teeth and the intact tooth of the other side of the jaw in the same patient. Values of SP and NKA were measured by ELISA test.

RESULTS

The mean concentration of SP in GCF of painful carious and healthy teeth was 2.65 ± 0.56 and 1.83 ± 0.65 pcgr/ml, respectively. This value was 2.29 ± 0.29 and 1.61 ± 0.35 pcgr/ml for NKA concentration in carious and healthy teeth as well.

CONCLUSION

Significant higher levels of both SP and NKA in GCF of painful carious teeth were observed, which is in line with previous studies' findings.

Inflammatory and immune pathways in the pathogenesis of periodontal disease

The pathogenesis of periodontitis involves a complex immune/inflammatory cascade that is initiated by the bacteria of the oral biofilm that forms naturally on the teeth. The susceptibility to periodontitis appears to be determined by the host response; specifically, the magnitude of the inflammatory response and the differential activation of immune pathways. The purpose of this review was to delineate our current knowledge of the host response in periodontitis. The role of innate immunity, the failure of acute inflammation to resolve (thus becoming chronic), the cytokine pathways that regulate the activation of acquired immunity and the cells and products of the immune system are considered. New information relating to regulation of both inflammation and the immune response will be reviewed in the context of susceptibility to, and perhaps control of, periodontitis.

Gingival Crevicular Fluid Levels of Neuropeptides following Dental Restorations

Purpose

Local neuropeptide release has a critical role in the initiation and progression of an inflammatory response. This study investigated the effects of different restorative materials on periodontium in this regard, by evaluating their neuropeptide-producing effects on gingival crevicular fluid (GCF).

Methods

The study included 14 patients suitable for metal-ceramic, composite and amalgam restorations. Four weeks after periodontal therapy, the restorations were performed. Study groups were constituted regarding the tooth/restoration surfaces contacting gingiva in each patient: 1 ceramic surface of a metal-ceramic crown (ceramic group), its opposite metal surface (metal group), 1 composite surface (composite group), its opposite enamel surface (opposite-composite group), 1 amalgam surface (amalgam group), its opposite enamel surface (opposite-amalgam group) and 1 nonrestored enamel surface (enamel group). Four weeks after dental restorations, clinical data and GCF were obtained from the group sites. Clinical data, GCF volume and its proinflammatory cytokine profile were utilized to evaluate the periodontal health. GCF levels of substance P (SP), neurokinin A (NKA) and calcitonin-gene related peptide (CGRP) were determined by ELISA for revealing the neuropeptide levels.

Results

GCF volume was found to increase in all groups compared with the enamel group (p<0.05). SP and NKA levels were higher in the ceramic, composite and amalgam groups than those in the enamel group (p<0.05). SP and NKA levels were also higher in the composite and amalgam groups than those in the opposite-composite/amalgam groups (p<0.05).

Conclusions

These results suggest that ceramic, composite and amalgam materials may uniquely trigger local neuropeptide release in periodontium.

Neutral endopeptidase regulates neurogenic inflammatory responses induced by stimulation of human oral keratinocytes with bacterial lipopolysaccharide and nicotine

Neutral endopeptidase (NEP) is present on various epithelial cells and inactivates numerous physiologically active peptides. Neutral endopeptidase may regulate proinflammatory signals in oral mucosal epithelium. However, the function of NEP in oral mucosal epithelium is unknown. The present study investigated the action of NEP upon proinflammatory signals on human oral keratinocytes and the influence of endothelin-converting enzyme (ECE)-1, an enzyme similar to NEP, on the functions of NEP. Oral keratinocytes were cultured in medium containing inflammatory inducers [lipopolysaccharide (LPS) and nicotine], NEP inhibitors, and ECE-1/NEP inhibitors, either alone or in combination. The concentrations of substance P (SP) and interleukin-1β (IL-1β) were measured in the supernatant. Additionally, the concentrations of SP and IL-1β were measured in the supernatant of cells incubated with LPS or nicotine after transfection with NEP small interfering RNA (siRNA). The concentrations of SP and IL-1β were significantly increased in cells incubated with NEP inhibitors and, to a lesser extent, in cells incubated with ECE-1/NEP inhibitors, compared with controls (cells incubated with LPS or nicotine alone). The concentrations of SP and IL-1β in cells transfected with NEP siRNA were significantly augmented compared with controls. In conclusion, the present study demonstrated that NEP down-regulated the levels of SP and IL-1β produced from human oral keratinocytes, although ECE-1 may be partly related to the down-regulation.

Mapping biological to clinical phenotypes during the development (21 days) and resolution (21 days) of experimental gingivitis

AIM

To characterize and map temporal changes in the biological and clinical phenotype during a 21-day experimental gingivitis study.

MATERIALS AND METHODS

Experimental gingivitis was induced over 21 days in healthy human volunteers (n = 56), after which normal brushing was resumed (resolution phase). Gingival and plaque indices were assessed. Gingival crevicular fluid was collected from four paired test and contra-lateral control sites in each volunteer during induction (Days 0, 7, 14 and 21) and resolution (Days 28 and 42) of experimental gingivitis. Fluid volumes were measured and a single analyte was quantified from each site-specific, 30s sample. Data were evaluated by analysis of repeated measurements and paired sample tests.

RESULTS

Clinical indices and gingival crevicular fluid volumes at test sites increased from Day 0, peaking at Day 21 (test/control differences all p < 0.0001) and decreased back to control levels by Day 28. Levels of four inflammatory markers showed similar patterns, with significant differences between test and control apparent at Day 7 (substance P, cathepsin G, interleukin-1β, elastase: all p < 0.03) and peaking at Day 21 (all p < 0.002). Levels of α-1-antitrypsin showed no pattern.

CONCLUSIONS

Levels of substance P, cathepsin G, interleukin-1β and neutrophil elastase act as objective biomarkers of gingival inflammation induction and resolution that typically precede phenotypical changes.

Antimicrobial peptides and periodontal disease

AIMS

The goal of this review is to identify the antimicrobial proteins in the oral fluids, saliva and gingival crevicular fluid and identify functional families and candidates for antibacterial treatment.

RESULTS

Periodontal biofilms initiate a cascade of inflammatory and immune processes that lead to the destruction of gingival tissues and ultimately alveolar bone loss and tooth loss. Treatment of periodontal disease with conventional antibiotics does not appear to be effective in the absence of mechanical debridement. An alternative treatment may be found in antimicrobial peptides and proteins, which can be bactericidal and anti-inflammatory and block the inflammatory effects of bacterial toxins. The peptides have co-evolved with oral bacteria, which have not developed significant peptide resistance. Over 45 antibacterial proteins are found in human saliva and gingival crevicular fluid. The proteins and peptides belong to several different functional families and offer broad protection from invading microbes. Several antimicrobial peptides and proteins (AMPs) serve as templates for the development of therapeutic peptides and peptide mimetics, although to date none have demonstrated efficacy in human trials.

CONCLUSIONS

Existing and newly identified AMPs may be developed for therapeutic use in periodontal disease or can serve as templates for peptide and peptide mimetics with improved therapeutic indices.

Proteomic analysis of a noninvasive human model of acute inflammation and its resolution: the twenty-one day gingivitis model

The 21-day experimental gingivitis model, an established noninvasive model of inflammation in response to increasing bacterial accumulation in humans, is designed to enable the study of both the induction and resolution of inflammation. Here, we have analyzed gingival crevicular fluid, an oral fluid comprising a serum transudate and tissue exudates, by LC-MS/MS using Fourier transform ion cyclotron resonance mass spectrometry and iTRAQ isobaric mass tags, to establish meta-proteomic profiles of inflammation-induced changes in proteins in healthy young volunteers. Across the course of experimentally induced gingivitis, we identified 16 bacterial and 186 human proteins. Although abundances of the bacterial proteins identified did not vary temporally, Fusobacterium outer membrane proteins were detected. Fusobacterium species have previously been associated with periodontal health or disease. The human proteins identified spanned a wide range of compartments (both extracellular and intracellular) and functions, including serum proteins, proteins displaying antibacterial properties, and proteins with functions associated with cellular transcription, DNA binding, the cytoskeleton, cell adhesion, and cilia. PolySNAP3 clustering software was used in a multilayered analytical approach. Clusters of proteins that associated with changes to the clinical parameters included neuronal and synapse associated proteins.

Biologic markers for odontogenic periradicular periodontitis

INTRODUCTION

The diagnosis and assessment of apical periodontitis by traditional periapical radiographs can be challenging and might yield false-negative results. The aim of this study was to determine whether interleukin-1beta (IL-1beta) and dentin sialoprotein (DSP) in gingival crevicular fluid (GCF) can be used as biological markers for apical periodontitis.

METHODS

Forty healthy patients with teeth diagnosed with apical periodontitis of pulpal origin were included in the study. GCF samples were obtained from the diseased tooth and from a healthy contralateral control tooth. Total protein concentration in each sample was determined by using the Bio-Rad protein assay. Enzyme-linked immunosorbent assay was used to analyze the concentration of IL-1beta and DSP in the samples.

RESULTS

Protein content of the GCF was statistically significantly higher in the disease group compared with the control group. The levels of IL-1beta and DSP were not statistically different between disease and control groups.

CONCLUSIONS

Although this study was unable to demonstrate a significantly higher level of IL-1beta or DSP in the GCF of teeth with apical periodontitis, the observed presence of a significantly higher level of total protein in the GCF of diseased teeth suggests the possible role of total protein level as a marker for periapical disease.

Oral infections and orofacial pain in Alzheimer's disease: Case report and review

Dental infections, frequent in the general population, are a common cause of inflammation with systemic impact, and are the most common cause of orofacial pain. Temporomandibular disorders are also frequent in the elderly and represent an important cause of secondary headache. Both inflammation and pain can also contribute to cognitive, functional and behavioral impairment of the elderly and aggravate symptoms of patients with Alzheimer's disease (AD). We report a case of a 74-year-old woman with AD and chronic facial pain who had a significant improvement in functional activities as well as in cognition and depressive symptoms after successful treatment of her facial pain. Patients with AD have higher compromise of oral health with infections and teeth loss. The investigation of orofacial pain should be performed in patients with AD, because of the associations reviewed and given the potential for improvement as highlighted by this case.

Neuropeptide Y (NPY) and NPY Y1 receptor in periodontal health and disease

OBJECTIVES

Neuropeptide Y (NPY) coordinates inflammation and bone metabolism which are central to the pathogenesis of periodontitis. The present study was designed to determine whether NPY was quantifiable in human gingival crevicular fluid (GCF) and to test the null hypothesis that GCF levels of NPY were the same in periodontal health and disease. A subsidiary aim was to determine the potential functionality of released NPY by detecting the presence of NPY Y1 receptors in gingival tissue.

DESIGN

The periodontitis group consisted of 20 subjects (10 females and 10 males) mean age 41.4 (S.D. 9.6 years). The control group comprised 20 subjects (10 females and 10 males) mean age 37.4 (S.D. 11.7 years). NPY levels in GCF were measured in periodontal health and disease by radioimmunoassay. NPY Y1 receptor expression in gingival tissue was determined by Western blotting of membrane protein extracts from healthy and inflamed gum.

RESULTS

Healthy sites from control subjects had significantly higher levels of NPY than diseased sites from periodontitis subjects. NPY Y1 receptor protein was detected in both healthy and inflamed gingival tissue by Western blotting.

CONCLUSIONS

The significantly elevated levels of NPY in GCF from healthy compared with periodontitis sites suggests a tonic role for NPY, the functionality of which is indicated by the presence of NPY Y1 receptors in local gingival tissue.

Gingival crevicular fluid and plasma levels of neuropeptide Substance-P in periodontal health, disease and after nonsurgical therapy

BACKGROUND AND OBJECTIVE

The level of Substance-P in gingival crevicular fluid has been found to correlate with clinical measures of periodontal disease. The present study was designed to assess the relationship between clinical parameters and levels of Substance-P in the gingival crevicular fluid from inflamed gingiva, periodontitis sites and after treatment of periodontitis sites, and to correlate them to the Substance-P levels of plasma.

MATERIAL AND METHODS

Thirty, age- and gender-matched subjects were divided into three groups (healthy, gingivitis and chronic periodontitis) based on modified gingival index scores and clinical attachment loss. A fourth group consisted of 10 subjects from the periodontitis group, 6-8 wk after initial therapy. Plasma and gingival crevicular fluid samples were collected and quantified for Substance-P using an enzyme immunoassay.

RESULTS

The mean concentration of Substance-P, both in gingival crevicular fluid and plasma, was observed to be highest in the periodontitis group (45.13 pg/mL in gingival crevicular fluid and 67.8 pg/mL in plasma) and lowest in the healthy group (6.07 pg/mL in gingival crevicular fluid and below the detection level in plasma). The mean Substance-P concentration in the gingivitis group (11.42 pg/mL in gingival crevicular fluid and 38.8 pg/mL in plasma) and in the after-treatment group (7.58 pg/mL in gingival crevicular fluid and 39.7 pg/mL in plasma) lay between the highest and lowest values. In all groups the gingival crevicular fluid levels showed a statistically significant positive correlation with that of plasma and clinical attachment loss.

CONCLUSION

Substance-P levels were highest in the gingival crevicular fluid from sites with periodontal destruction; however, periodontal treatment resulted in the reduction of Substance-P levels. Gingival crevicular fluid and plasma Substance-P levels showed a positive correlation in all of the groups.

Experimental tooth pain elevates substance P and matrix metalloproteinase-8 levels in human gingival crevice fluid

OBJECTIVE

Tooth pain can induce a neurogenic inflammatory reaction in gingiva in association with local elevations of matrix metalloproteinase (MMP)-8, which is considered the major tissue destructive protease in gingival crevice fluid (GCF). The pro-inflammatory neuropeptides released by sensory nerves coordinate the activities of the immuno-effector cells and may influence the secretion of MMP-8. With this background, we studied whether experimental tooth pain can trigger changes in GCF levels of the neuropeptide substance P (SP) and MMP-8.

MATERIAL AND METHODS

The GCF SP levels of stimulated and non-stimulated teeth were analyzed for SP using a competitive enzyme immunoassay (EIA). The GCF MMP-8 levels were determined by quantitative immunofluorometric assay (IFMA).

RESULTS

Painful stimulation of the upper central incisor caused significant elevations in GCF SP and MMP-8 levels of the stimulated tooth. At the same time, the GCF SP and MMP-8 levels of non-stimulated control teeth were unchanged.

CONCLUSIONS

These data indicate that experimental tooth pain can induce local elevations of SP and MMP-8 levels in GCF simultaneously. This supports the possibility of a local neurogenic spread of inflammatory reactions from intrapulpal to surrounding periodontal tissues.

Composition changes in gingival crevicular fluid during orthodontic tooth movement: comparisons between tension and compression sides

The aim of this study was to evaluate whether the application of tension or compression forces exerted on the periodontium during the early phase of orthodontic tooth movement is reflected by differences in the composition of the gingival crevicular fluid (GCF), at the level of interleukin-1beta (IL-1beta), substance P (SP), and prostaglandin E(2) (PGE(2)). Eighteen children (mean age 10.8 yr) starting orthodontic treatment were included in the study. Molar elastic separators were inserted mesially to two first upper or lower molars. One of the antagonist molars served as the control. GCF was collected from the mesial and distal sites of each molar, before (-7 d, 0 d) and immediately after (1 min, 1 h, 1 d, and 7 d) the placement of separators. The levels of IL-1beta, SP, and PGE(2) were determined by enzme-linked immunosorbent assay. At the orthodontically moved teeth, the GCF levels of IL-1beta, SP, and PGE(2) were significantly higher than at the control teeth in both tension and compression sides, and at almost all occasions after insertion of separators. The increase, relative to baseline values, was generally higher in tension sides. For the control teeth, the three mediators remained at baseline levels throughout the experiment. The results suggest that IL-1beta, SP, and PGE(2) levels in the GCF reflect the biologic activity in the periodontium during orthodontic tooth movement.

Pain Discomfort and Crevicular Fluid Changes Induced by Orthodontic Elastic Separators in Children

The objective of the present investigation was to study the experience of pain after placement of orthodontic elastic separators and the possible associations with the gingival crevicular fluid (GCF) composition changes at the level of interleukin 1-beta (IL-1beta), substance P (SP), and prostaglandin-E2 (PGE2). Eighteen children (mean age 10.8 yrs) in the beginning of the orthodontic treatment were included. Molar elastic separators were inserted mesially to 2 first upper or lower molars. One of the antagonist molars served as control. The GCF was collected from the distobuccal and distopalatal sites from each molar, before (day -7, day 0) and after the placement of separators (1 h, day 1, and day 7). Pain intensity was recorded using a visual analog scale (VAS). The contents of IL-1beta, SP, and PGE2 were determined by enzyme-linked immunosorbent assay. Pain intensity increased after 1 h (VAS = 11) and remained high on day 1 (VAS = 13). On day 7, no significant pain was reported. After 1 h, 1 day, and 7 days, mean GCF IL-1beta levels were significantly elevated at treatment teeth compared to control teeth (highest day 1). The GCF levels of SP and PGE2 for the treatment teeth were significantly higher at day 1 and day 7 than the control teeth. All 3 mediators remained at baseline levels throughout the experiment for the control teeth. The intensity of pain at 1 h was associated to PGE2 levels (R2 = 0.38; P < .05), whereas at day 1, the intensity of pain was associated to IL-1beta levels (R2 = 0.63, P < .0001). Thus, we report a rapid release of biochemical markers (1 h) that peaked after 1 day and partially decreased 7 days later. The intensity of pain followed a similar pattern. Associations were found between the experience of pain intensity and the GCF mediator levels.

PERSPECTIVE

The study may help to detect, in an initial stage, individuals prone to perceive higher level of pain during orthodontic treatment. This may help in the development of methods that will better control and/or alleviate the discomfort of pain during tooth movement.

Radioimmunoassay quantification of adrenomedullin in human gingival crevicular fluid

OBJECTIVE

To investigate whether adrenomedullin (ADM), a multifunctional peptide with key roles in host antimicrobial defence and inflammation, was present and quantifiable in human gingival crevicular fluid (GCF) and to study its relationship with periodontal health and disease.

DESIGN

GCF samples (30s) were collected using perio-paper strips from one diseased site in 21 subjects with periodontal disease and one healthy site from 19 control subjects with no evidence of periodontal disease. Samples were analysed by radioimmunoassay using a specific anti-human ADM antibody.

RESULTS

Measurable adrenomedullin-like immunoreactivity (ADM-LI) was present in all the GCF samples collected. ADM-LI was significantly higher in periodontitis sites (mean 493.6 pg) than in control healthy sites (mean 248.5 pg), p = 0.0016.

CONCLUSION

It is concluded that ADM is present in GCF at levels at which it could have an antibacterial role in the gingival crevice and modulate the pathophysiology of periodontal inflammation.

Expression of CD13/aminopeptidase N on human gingival fibroblasts and up-regulation upon stimulation with interleukin-4 and interleukin-13

BACKGROUND AND OBJECTIVES

Aminopeptidase N (APN)/CD13 is a multifunctional ectoenzyme that is involved in anti-inflammatory reactions, control of immune reactions and differentiation of many cellular systems. Here, we hypothesized that CD13/APN would be expressed on human gingival fibroblasts (hGF) and would contribute to the regulation of immune responses in periodontal tissue.

METHODS AND RESULTS

CD13/APN was expressed on hGF at the mRNA and protein levels as determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and flow cytometry, respectively. Enzymatic activities accompanying the expression were assessed by colorimetrical analysis using the synthetic substrate Leu-p-nitroanilide. We examined the possible regulation of CD13/APN expression on hGF in response to T cell-derived cytokines. T helper (Th) 2 cell type cytokines such as interleukin-4 and interleukin-13, but not interleukin-2 or interleukin-15, preferentially increased the expression of proteins as well as the enzymatic activities of CD13/APN in a dose-dependent manner. Receptors for these cytokines, the interleukin-4 receptor alpha chain, interleukin-13 receptor alpha1 chain, and interleukin-2R common gamma chain, were expressed on hGF assessed by RT-PCR or flow cytometry. hGF exhibited inhibitory effects for formyl-methionyl-leucyl-phenylalanine (FMLP)-induced polymorphonuclear leukocyte-activation that was evaluated by Mac-1 expression, and this inhibitory effect was partially recovered by pre-treatment with the APN-specific inhibitor bestatin.

CONCLUSIONS

These findings suggested that CD13/APN expressed by hGF could contribute to the anti-inflammatory response in periodontal tissue, and may be involved in disease processes mediated by Th2 cells.

Substance P enhances the inhibition of osteoblastic cell differentiation induced by lipopolysaccharide from Porphyromonas gingivalis

BACKGROUND

Substance P (SP) is a multifunctional neuropeptide that transmits pain signals, regulates the immune system, and may modulate emotional stress. SP stimulates bone resorption activity of osteoclasts, and SP level in gingival crevicular fluid is correlated with the degree of periodontal inflammation. However, the exact roles of SP in bone metabolism and periodontal diseases are poorly understood. To elucidate the effect of stress on bone metabolism, we investigated the effect of SP on osteoblastic cell differentiation in the presence of lipopolysaccharide from Porphyromonas gingivalis (P-LPS).

METHODS

The primary osteoblastic cells were isolated from fetal rat calvaria (RC) and cultured with SP, P-LPS, and an SP antagonist (SPa). The effects of SP on bone nodule (BN), alkaline phosphatase (ALPase) activity, mRNA expressions of SP receptor, bone matrix proteins, and Cbfa 1 were investigated.

RESULTS

SP stimulated the expression of SP receptor mRNA in RC cells and enhanced its expression in the presence of P-LPS (50 ng/ml). SP inhibited BN formation and ALPase activity in a dose-dependent manner (10(-7) to 10(-5) M) and further suppressed mRNA expression of bone sialoprotein, osteopontin, and osteocalcin but not of type I collagen mRNA. The inhibitory effects were enhanced in the presence of P-LPS and blocked by Spantide III. Furthermore, the expression of Cbfa 1 mRNA was also markedly suppressed in the presence of SP and P-LPS.

CONCLUSION

These findings suggest that SP inhibits osteoblastic cell differentiation and may be related to bone metabolism in periodontal diseases under conditions of stress.

Modulation of clinical expression of plaque-induced gingivitis. II. Identification of "high-responder" and "low-responder" subjects

AIM

The aims of this study were to validate a randomized, split-mouth, localized experimental gingivitis model and to identify subjects with different gingivitis susceptibility.

MATERIAL AND METHODS

In each of 96 healthy subjects, one maxillary quadrant was randomly assigned as "test" (experimental gingivitis) and the contralateral quadrant as "control". Plaque index (PlI), gingival index (GI), gingival crevicular fluid volume (GCF), and angulated bleeding score (AngBS) were recorded in both quadrants at days 0, 7, 14, and 21. Cumulative plaque exposure (CPE), i.e. PlI over time, was calculated. Day-21 GCF was standardized according to CPE, and residuals of GCF on CPE were calculated. Two subpopulations were then defined, based on upper and lower quartiles of GCF-residual distribution and were, respectively, identified as "high-responder" (HR; n=24) and "low-responder" (LR; n=24).

RESULTS

At test quadrants, all parameters significantly increased throughout the trial, while in control quadrants, PlI, GI, and AngBS remained low. Significant differences were noted between test and control quadrants on days 7, 14, and 21 for all parameters. Significant increases in GI, AngBS, and GCF were observed in test quadrants over the course of the study in both HR and LR groups. Significant differences were noted between HR and LR groups for all gingivitis parameters on day 21 in test quadrants, without any significant differences in PlI or CPE between the groups.

CONCLUSIONS

We identified two subpopulations characterized by significant differences in clinical parameters of plaque-induced gingival inflammation, despite similar amounts of plaque deposits and plaque accumulation rates.

Soluble Cell Adhesion Molecules in Gingival Crevicular Fluid in Periodontal Health and Disease

BACKGROUND

Cell adhesion molecules (CAMs) are cell surface proteins involved in the binding of cells to each other, to endothelial cells, or to the extracellular matrix. The soluble forms of CAMs (sCAMs) are thought to be produced by proteolytic cleavage from the cell surface and are shed into the gingival crevicular fluid (GCF). The aim of this study was to investigate whether sCAMs, sICAM-1, sVCAM-1, and sE-Selectin were present in GCF in both periodontal health and disease and to examine their relationship with periodontal inflammation.

METHODS

GCF was collected from a clinically healthy, a gingivitis, and a periodontitis site in 29 subjects with chronic periodontitis and from a single clinically healthy site in 22 subjects without chronic periodontitis. The volume of GCF was measured and each sample was analyzed for sCAMs by enzyme-linked immunosorbent assay (ELISA). The effect of treatment (oral hygiene instruction, scaling and root planing) on the levels of sCAMs in each site of the diseased group was also investigated.

RESULTS

Statistically significant differences (P < 0.05) were found between the levels of sVCAM-1 in periodontal health and disease. These results indicate that changes in the levels of sCAMs may be a sensitive indicator to differentiate healthy sites from those with periodontitis. Statistically significant changes in the levels of sICAM-1 were recorded after treatment (P < 0.05).

CONCLUSIONS

Further studies are required to establish if these potential biomarkers will enable the identification of those sites most at risk for disease progression and also evaluate the response to treatment, thereby playing a preventive role in the pathogenesis of periodontal disease.

NEUROPEPTIDES AND NEUROGENIC MECHANISMS IN ORAL AND PERIODONTAL INFLAMMATION

It is generally accepted that the nervous system contributes to the pathophysiology of peripheral inflammation, and a neurogenic component has been implicated in many inflammatory diseases, including periodontitis. Neurogenic inflammation should be regarded as a protective mechanism, which forms the first line of defense and protects tissue integrity. However, severe or prolonged noxious stimulation may result in the inflammatory response mediating injury rather than facilitating repair. This review focuses on the accumulating evidence suggesting that neuropeptides have a pivotal role in the complex cascade of chemical activity associated with periodontal inflammation. An overview of neuropeptide synthesis and release introduces the role of neuropeptides and their interactions with other inflammatory factors, which ultimately lead to neurogenic inflammation. The biological effects of the neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), and neuropeptide Y (NPY) are summarized, and evidence for their involvement in the localized inflammatory lesions which characterize periodontitis is presented. In this context, the role of CGRP in bone metabolism is described in more detail. Recent research highlighting the role of the nervous system in suppressing pain and inflammation is also discussed.

Changes in vasoactive intestinal peptide in gingival crevicular fluid in response to periodontal treatment

AIMS

To evaluate the role of the anti-inflammatory neuropeptide vasoactive intestinal peptide (VIP) in periodontal health and disease and to determine the effects of periodontal treatment, resulting in a return to periodontal health, on the levels of VIP in gingival crevicular fluid (GCF).

METHODS

At baseline, 10 subjects with periodontitis (nine females, one male, mean age 43.0, SD 7.3) started a course of non-surgical periodontal treatment. Clinical indices were measured at one periodontitis and one clinically healthy site at an initial visit and at 8 weeks after the completion of treatment in each subject. A 30-s sample of GCF was collected from each test site using perio paper strips. The volume of GCF was measured and each sample subsequently analysed for VIP by radioimmunoassay. One healthy site was sampled from each member of a control group (10 females, mean age 29.9, SD 8.2 years) with clinically healthy gingiva and no periodontitis.

RESULTS

The clinical condition of all periodontitis sites improved as a result of periodontal treatment. The levels of VIP (pg/30 s sample) in periodontitis-affected sites fell significantly from 302.0 (SD 181.2) at the initial visit to 78.0 (54.4) after treatment, p = 0.007. The reduction in the concentration of VIP (pg/ micro L) in GCF from 524.3 (322.3) to 280.8 (280.2) was not statistically significant. The levels of VIP in clinically healthy sites fell from 115.5.5 (74.3) to 77.8 (32.3), n.s. and the concentration changed little from 883.8 (652.1) to 628.7 (323.3), n.s. There were substantially smaller amounts of VIP (25.8, SD 12.8) pg in healthy sites sampled from control subjects.

CONCLUSIONS

VIP is present in GCF in greater quantities in periodontitis-affected than clinically healthy sites. In addition, the reduction in inflammation resulting from effective periodontal treatment is associated with a reduction in the levels of VIP in gingival crevicular fluid.

Quantitative analysis of substance P, neurokinin A and calcitonin gene-related peptide in gingival crevicular fluid associated with painful human teeth

The aim of this study was to investigate the presence of substance P (SP), neurokinin A (NKA) and calcitonin gene-related peptide (CGRP) in the gingival crevicular fluid of teeth diagnosed with pain of pulpal origin compared with clinically healthy teeth, and to detect any changes in the levels of these neuropeptides in gingival crevicular fluid after removal of the pulp from the painful teeth. Gingival crevicular fluid was collected at baseline from one interproximal site at a painful and a non-painful contralateral tooth from 54 adult patients. Sampling was repeated after 1 wk in a subset of 21 subjects. Samples were analysed for SP, NKA, and CGRP using radioimmunoassay. The mean levels of SP and NKA were significantly higher in gingival crevicular fluid from painful teeth compared with non-painful teeth. The level of SP in the GCF of painful teeth fell significantly 1 wk after pulpectomy. In contralateral teeth, there were no significant differences in the levels of SP and NKA after 1 wk. It is concluded that SP and NKA are present in significantly greater amounts in the GCF of painful teeth compared with healthy teeth.

Quantitative analysis of MRP-8 in gingival crevicular fluid in periodontal health and disease using microbore HPLC

BACKGROUND

The protein components of GCF can be separated by reverse-phase microbore HPLC on a C18 column with detection on the basis of 214 nm absorbance. A single major symmetrical protein peak eluting with a retention time of 26 min (50% acetonitrile) was evident in gingival crevicular fluid (GCF) from periodontitis patients but not in healthy GCF. This protein was identified as human MRP-8 by N-terminal amino acid sequencing and liquid chromatography quadropole mass spectrometry.

AIMS

To quantify the amount of MRP-8 detectable in GCF from individual healthy, gingivitis and periodontitis affected sites and to study the relationship, if any, between the levels of this responsive protein and periodontal health and disease.

METHODS

GCF was sampled (30 s) from healthy, gingivitis, and periodontitis sites in peridontitis subjects (n=15) and from controls (n=5) with clinically healthy gingiva and no periodontitis. Purified MRP-8 was sequenced by Edmann degradation and the phenylthiohydantoin (PTH) amino acid yield determined (by comparison of peak area with external PTH amino acid standards). This value was subsequently used to calculate the relative amount of protein in the peak eluting with a retention time of 26.0 min (MRP-8) in individual GCF chromatograms.

RESULTS

Higher levels of MRP-8 were detected in inflammatory sites: periodontitis 457.0 (281.0) ng; gingivitis 413.5 (394.5) ng compared with periodontally healthy sites in diseased subjects 14.6 (14.3) ng and in controls 18.6 (18.5) ng, p=0.003. There was at least 20-fold more MRP-8 in the inflammatory compared with the healthy sites studied.

CONCLUSIONS

The preliminary data indicate that MRP-8 is present in GCF, with significantly greater amounts present at diseased than healthy sites. A systematic study of the relationship of this protein to periodontal disease could prove useful in further clarifying whether MRP-8 could be a reliable GCF biomarker of gingivitis and periodontitis.

Capsaicin-evoked CGRP release from rat buccal mucosa: development of a model system for studying trigeminal mechanisms of neurogenic inflammation

Many of the physiological hallmarks associated with neurogenic inflammatory processes in cutaneous tissues are similarly present within orofacial structures. Such attributes include the dependence upon capsaicin-sensitive sensory neurons and the involvement of certain inflammatory mediators derived therein, including calcitonin gene-related peptide (CGRP). However, there are also important differences between the trigeminal and spinal nervous systems, and the potential contributions of neurogenic processes to inflammatory disease within the trigeminal system have yet to be fully elucidated. We present here a model system that affords the ability to study mechanisms regulating the efferent functions of peptidergic terminals that may subserve neurogenic inflammation within the oral cavity. Freshly dissected buccal mucosa tissue from adult, male, Sprague-Dawley rats was placed into chambers and superfused with oxygenated, Krebs buffer. Serial aliquots of the egressing superfusate were acquired and analysed by radioimmunoassay for immunoreactive CGRP (iCGRP). Addition of the selective excitotoxin, capsaicin (10-300 microm), to the superfusion buffer resulted in a significant, concentration-dependent increase in superfusate levels of iCGRP. Similarly, release of iCGRP from the buccal mucosa could also be evoked by a depolarizing concentration of potassium chloride (50 mm) or by the calcium ionophore A23187 (1 microm). The specific, capsaicin receptor antagonist, capsazepine (300 microm), completely abolished the capsaicin-evoked release of iCGRP while having no effect whatsoever on the potassium-evoked release. Moreover, capsaicin-evoked release was dependent upon the presence of extracellular calcium ions and was significantly, though incompletely, attenuated by neonatal capsaicin denervation. Collectively, these data indicate that the evoked neurosecretion of iCGRP in response to capsaicin occurs via a vanilloid receptor-mediated, exocytotic mechanism. The model system described here should greatly facilitate future investigations designed to identify and characterize the stimuli that regulate the release of CGRP or other neurosecretory substances in isolated tissues. This system may also be used to elucidate the role of these mediators in the aetiology of inflammatory processes within the trigeminal field of innervation.

Interactions of lymphotoxin alpha (TNF-beta), angiotensin-converting enzyme (ACE), and endothelin-1 (ET-1) gene polymorphisms in adult periodontitis

BACKGROUND

Adult periodontitis is a complex multifactorial disease whose etiology is not well defined. To investigate whether the genes encoded within the HLA class III region may confer susceptibility to periodontitis, polymorphisms in the ET-1 and TNF-beta genes were analyzed together with the I/D polymorphism of the ACE gene.

METHODS

We determined allele and genotype frequencies of the NcoI bi-allelic polymorphism of the TNF-beta gene, the I/D (insertion/deletion) polymorphism of the ACE gene, and the TaqI polymorphism of the ET-1 gene in 63 Caucasian patients with adult periodontitis and 95 orally healthy controls.

RESULTS

We found a significant difference in a 3 locus combination of genotypes between patients and controls (P<0.05). In the next analyses, no significant differences were found in allele frequencies of single genes, but we did find a significant difference in the genotype distribution between cases and controls for TNF-beta (P<0.03). Differences were also observed for 2 locus combinations of ACE and TNF-beta genotypes (P<0.03), and the ET-1 and TNF-beta (P<0.05) genes. Evidence of deviation from Hardy-Weinberg equilibrium was observed in the periodontitis group for TNF-beta, with an absence of the B1B1 homozygotes in patients.

CONCLUSIONS

This study is of an exploratory nature. Considering the number of significant results, however, at least a part of the observed associations may obviously be real and our findings suggest that interactions of the TNF-beta, ET-1, and ACE genes may be involved in susceptibility to adult periodontitis.

Identification of MRP-8 (calgranulin A) as a major responsive protein in chronic periodontitis

The purpose of the study was to analyse how the protein composition of the inflammatory exudate associated with chronic periodontitis differed from the exudate in periodontal health. Gingival crevicular fluid (GCF) was collected from sites with chronic periodontal inflammation and from non-diseased sites in healthy control subjects. Microbore HPLC analysis revealed one major difference in GCF protein profiles between healthy controls and periodontitis patients. The protein enhanced in periodontitis patients was identified as migration inhibitory factor-related protein-8 (MRP-8) by a combination of N-terminal amino acid sequencing, mass spectrometry, and SDS-PAGE. Together, these data demonstrate, for the first time, the presence of monomeric MRP-8 in an inflammatory exudate. Whether monomeric MRP-8 is a unique feature of chronic periodontal inflammation is not yet clear, but the chemotactic properties of this peptide support a functional role for MRP-8 in periodontal inflammation.

Neurokinin mediation of edema and inflammation

The aim of this article is to furnish a brief review of the role played by neurokinins in the inflammatory process. Further attention is given to the mechanisms, as well as to the receptor subtypes involved in neurokinin-mediated inflammation, in an attempt to clarify the participation of neurokinins in different models of acute and chronic inflammation. The involvement of SP, NKA and NKB is also examined in relation to the major signs of inflammation, including edema formation, protein plasma extravasation and vasodilatation. Finally, we provide a general overview on the potential clinical applications of neurokinin antagonists, along with the involvement of neurokinins in human diseases.