Ability of matrix metalloproteinase-8 biosensor, IFMA, and ELISA immunoassays to differentiate between periodontal health, gingivitis, and periodontitis.

OBJECTIVE: The aim of this study was to determine the diagnostic utility of an MMP-8 biosensor assay in differentiating periodontal health from gingivitis and periodontitis and compare it with an established time-resolved immunofluorescence assay (IFMA) and enzyme-linked immunosorbent assay (ELISA). BACKGROUND: Currently available antibody-based assays display a wide variability in their ability to accurately measure matrix metalloproteinase-8 (MMP-8) levels in saliva. METHODS: Salivary MMP-8 levels were analyzed in 189 systemically healthy participants using an antibody-based biosensor prototype that operates using a surface acoustic wave technology and compared with IFMA and ELISA antibody assays. Participants were categorized into 3 groups: periodontal health (59), gingivitis (63), and periodontitis (67). A sub-population of participants (n = 20) with periodontitis received periodontal treatment and were monitored for 6 months. RESULTS: All the assays demonstrated significantly higher salivary MMP-8 concentrations in participants with periodontitis versus gingivitis, periodontitis versus health, and gingivitis versus health (all p < .05). The biosensor data demonstrated significant correlations with IFMA (r = .354, p < .001) and ELISA (r = .681, p < .001). Significant reductions in salivary MMP-8 concentrations were detected by the biosensor (p = .030) and IFMA (p = .002) in participants with periodontitis 6 months after non-surgical periodontal treatment. IFMA had the best sensitivity (89.2%) for detecting periodontitis and gingivitis versus health and 96.6% for detecting periodontitis versus health and gingivitis. The biosensor had an AUC value of 0.81 and diagnostic accuracy of 74.2% for differentiating periodontitis and gingivitis from health; an AUC value of 0.86 and diagnostic accuracy of 82.8% for periodontitis versus health and gingivitis. CONCLUSIONS: The biosensor, IFMA, and ELISA assays differentiated between periodontal health, gingivitis, and periodontitis based on salivary MMP-8 levels. Only the biosensor and, particularly, IFMA identified an effect of periodontal treatment in the participants with periodontitis. Our findings support the potential utility of salivary oral fluid aMMP-8-based point-of-care technology in the future of periodontal diagnostics.

Discovery, validation, and diagnostic ability of multiple protein-based biomarkers in saliva and gingival crevicular fluid to distinguish between health and periodontal diseases.

AIM: To discover and validate differential protein biomarker expression in saliva and gingival crevicular fluid (GCF) to discriminate objectively between periodontal health and plaque-induced periodontal disease states. MATERIALS AND METHODS: One-hundred and ninety participants were recruited from two centres (Birmingham and Newcastle upon Tyne, UK) comprising healthy, gingivitis, periodontitis, and edentulous donors. Samples from the Birmingham cohort were analysed by quantitative mass spectrometry proteomics for biomarker discovery. Shortlisted candidate proteins were then verified by enzyme-linked immunosorbent assay in both cohorts. Leave-one-out cross validation logistic regression analysis was used to identify the best performing biomarker panels. RESULTS: Ninety-five proteins were identified in both GCF and saliva samples, and 15 candidate proteins were selected based upon differences discovered between the donor groups. The best performing panels to distinguish between: health or gingivitis and periodontitis contained matrix metalloproteinase-9 (MMP9), S100A8, alpha-1-acid glycoprotein (A1AGP), pyruvate kinase, and age (area under the curve [AUC] 0.970); health and gingivitis contained MMP9, S100A8, A1AGP, and pyruvate kinase, but not age (AUC 0.768); and mild to moderate and advanced periodontitis contained MMP9, S100A8, A1AGP, pyruvate kinase, and age (AUC 0.789). CONCLUSIONS: Biomarker panels containing four proteins with and without age as a further parameter can distinguish between periodontal health and disease states.

Levels of myeloid-related proteins in saliva for screening and monitoring of periodontal disease.

AIM: To evaluate the salivary levels of myeloid-related markers in relation to periodontal disease and their potential screening capability, as well as the effects of periodontal treatment on these markers in periodontitis patients. MATERIALS AND METHODS: Participants with a healthy periodontium (n = 60) and with gingivitis (n = 63) and periodontitis (n = 72) were recruited. Periodontitis patients received non-surgical treatment and were re-examined after 3 and 6 months. Unstimulated saliva was collected at baseline and at 1, 3, and 6 months after therapy for the periodontitis patients. Levels of colony-stimulating factor-1 (CSF-1), interleukin-34 (IL-34), S100A8/A9, S100A12, hepatocyte growth factor (HGF), IL-1ß, and matrix metalloproteinase-8 (MMP-8) were analysed by immunoassays. RESULTS: CSF-1, S100A8/A9, S100A12, IL-1ß, MMP-8, and HGF were significantly elevated in saliva from periodontitis and gingivitis patients in comparison to healthy individuals, whereas IL-34 was significantly lower in periodontitis compared to both healthy individuals and gingivitis patients. IL-34 increased significantly 3 months after treatment, while IL-1ß and MMP-8 decreased 1 month after therapy. Additionally, periodontitis patients clustered in high and low levels of S100A8/A9, whereby those with high levels had more bleeding, deeper pockets, and higher S100A12. CONCLUSIONS: Salivary levels of myeloid-related markers are altered in periodontitis and are partially modulated by periodontal treatment. Measuring S100A8/A9 in saliva may identify distinct groups of periodontitis patients.

Treatment of periodontitis reduces systemic inflammation in type 2 diabetes.

AIMS: To assess the impact of periodontal treatment on systemic inflammation in type 2 diabetes. MATERIALS AND METHODS: Adults with type 2 diabetes (n = 83) and without diabetes (controls, n = 75) were recruited, and participants with periodontitis received periodontal treatment and 12 months' follow-up. Biomarkers for periodontal inflammation (gingival crevicular fluid interleukin-6, tumour necrosis factor-α, interleukin-1ß, interferon-γ, matrix metalloproteinase-8, matrix metalloproteinase-9, adiponectin) and serum markers of inflammation and diabetes control (glycated haemoglobin, high sensitivity C-reactive protein, interleukin-6, tumour necrosis factor-α, interleukin-1ß, interferon-γ, leptin, adiponectin) were measured. Structural equation modelling was used to evaluate periodontal treatment effects on oral and systemic inflammation. RESULTS: Periodontal treatment resulted in significant improvements in clinical status and reductions in gingival crevicular fluid biomarkers from baseline to month 12. Structural equation modelling identified that, at baseline, individuals with diabetes and periodontitis had significantly higher systemic inflammation than non-diabetic controls with periodontitis (Δ = 0.20, p = .002), with no significant differences between groups for oral inflammation. There was a greater reduction in systemic inflammation following periodontal treatment in individuals with diabetes and periodontitis compared to those with periodontitis but not diabetes (Δ = -0.25, p = .01). CONCLUSIONS: Diabetes and periodontitis together appear to increase systemic inflammation, with evidence of reductions following periodontal treatment.

Age-related changes in immune function (immune senescence) in caries and periodontal diseases: a systematic review.

AIM: To systematically review the evidence regarding immune senescence in the pathogenesis of periodontitis and dental caries. METHODS: A systematic search of electronic databases utilizing medical subject headings (MeSH terms) supplemented by screening of review articles and other relevant texts was undertaken. RESULTS: Seventy-three articles were included (43 for periodontitis, 30 for caries). Study results were found to be generally heterogeneous. Regarding periodontitis, human studies suggest evidence for altered neutrophil function and increased production of pro-inflammatory mediators (e.g. interleukin-1ß, interleukin-6 and prostaglandin E2 ) in older compared to younger subjects, and animal experiments suggest increased expression of genes that contribute to a pro-inflammatory state in older compared to younger animals. Regarding dental caries, research relating to changes in immune functioning and the impact of ageing is in its infancy. A small number of studies have reported components of innate and adaptive immunity that affect the composition of saliva and dental biofilms with possible impacts on caries progression. CONCLUSION: There is evidence that immune functioning related to periodontitis and (less investigated) dental caries alters with increasing age. In both conditions, age-associated mechanistic changes in immune functioning are complex and incompletely understood and it is not clear how these relate to disease susceptibility.

Effectiveness of portable electronic and optical magnifiers for near vision activities in low vision: a randomised crossover trial.

PURPOSE: To compare the performance of near vision activities using additional portable electronic vision enhancement systems (p-EVES), to using optical magnifiers alone, by individuals with visual impairment. METHODS: A total of 100 experienced optical aid users were recruited from low vision clinics at Manchester Royal Eye Hospital, Manchester, UK, to a prospective two-arm cross-over randomised controlled trial. Reading, performance of near vision activities, and device usage were evaluated at baseline; and at the end of each study arm (Intervention A: existing optical aids plus p-EVES; Intervention B: optical aids only) which was after 2 and 4 months. RESULTS: A total of 82 participants completed the study. Overall, maximum reading speed for high contrast sentences was not statistically significantly different for optical aids and p-EVES, although the critical print size and threshold print size which could be accessed with p-EVES were statistically significantly smaller (p < 0.001 in both cases). The optical aids were used for a larger number of tasks (p < 0.001), and used more frequently (p < 0.001). However p-EVES were preferred for leisure reading by 70% of participants, and allowed longer duration of reading (p < 0.001). During the study arm when they had a p-EVES device, participants were able to carry out more tasks independently (p < 0.001), and reported less difficulty with a range of near vision activities (p < 0.001). CONCLUSIONS: The study provides evidence that p-EVES devices can play a useful role in supplementing the range of low vision aids used to reduce activity limitation for near vision tasks.

Gingival crevicular fluid and saliva.

Understanding the structure and function of the mouth, its tissues and secretions is of great interest to physiologists, cell biologists, immunologists and microbiologists but is also of fundamental interest to the dental professional interested in comprehending the aberrant processes associated with oral disease and in the application of effective clinical interventions. The field of periodontology, which has a truly multidisciplinary perspective cutting across leading edge molecular and cellular biology, clinical dentistry, epidemiology and behavioural science, exemplifies this. A paradigm shift in recent years has led to the consideration of the oral cavity (and, thus, oral disease) not in isolation but as a component integrated with systemic physiology, important in maintaining systemic health and reflective of systemic disease; this has served to promote periodontology, in particular, into the forefront of medicine in general. This volume of Periodontology 2000 considers the role of gingival crevicular fluid and saliva in physiological function, maintenance of oral tissue integrity, defense against pathogens and oral disease as well as the many, emerging applications of analysis of these fluids in support of periodontal disease diagnosis, prognosis and epidemiology. However, whilst the emphasis is on periodontal disease, the wider contexts of oral and systemic health are also key considerations.

Salivary cytokines as biomarkers of periodontal diseases.

Research into biomarkers of periodontitis is driven by mainly three targets: to identify 'at risk' patients before periodontal tissue destruction occurs; to determine disease activity and progression; and to build up our understanding of this complex disease with the purpose of finding new therapeutic targets. Whilst blood and gingival crevicular fluid were previously the biological samples of choice, saliva has recently gained more attention as a readily accessible oral fluid which has a mediator profile similar to that of serum and gingival crevicular fluid. The aim of this paper was to give a comprehensive overview of salivary cytokines in periodontitis, highlighting extensively studied cytokines such as interleukin-1beta and interleukin-6, but also cytokines that have been the subject of only a few studies and which warrant further investigation. Cross-sectional and longitudinal studies of salivary cytokines, and the potential of cytokines as periodontitis biomarkers, are evaluated. Finally, a discussion of potential confounding factors, such as concurrent systemic diseases and smoking, is presented.

DNA damage response at telomeres contributes to lung aging and chronic obstructive pulmonary disease.

Cellular senescence has been associated with the structural and functional decline observed during physiological lung aging and in chronic obstructive pulmonary disease (COPD). Airway epithelial cells are the first line of defense in the lungs and are important to COPD pathogenesis. However, the mechanisms underlying airway epithelial cell senescence, and particularly the role of telomere dysfunction in this process, are poorly understood. We aimed to investigate telomere dysfunction in airway epithelial cells from patients with COPD, in the aging murine lung and following cigarette smoke exposure. We evaluated colocalization of γ-histone protein 2A.X and telomeres and telomere length in small airway epithelial cells from patients with COPD, during murine lung aging, and following cigarette smoke exposure in vivo and in vitro. We found that telomere-associated DNA damage foci increase in small airway epithelial cells from patients with COPD, without significant telomere shortening detected. With age, telomere-associated foci increase in small airway epithelial cells of the murine lung, which is accelerated by cigarette smoke exposure. Moreover, telomere-associated foci predict age-dependent emphysema, and late-generation Terc null mice, which harbor dysfunctional telomeres, show early-onset emphysema. We found that cigarette smoke accelerates telomere dysfunction via reactive oxygen species in vitro and may be associated with ataxia telangiectasia mutated-dependent secretion of inflammatory cytokines interleukin-6 and -8. We propose that telomeres are highly sensitive to cigarette smoke-induced damage, and telomere dysfunction may underlie decline of lung function observed during aging and in COPD.

Leptin enhances the secretion of interleukin (IL)-18, but not IL-1ß, from human monocytes via activation of caspase-1.

Circulating levels of leptin are elevated in type-2 diabetes mellitus (T2DM) and leptin plays a role in immune responses. Elevated circulating IL-18 levels are associated with clinical complications of T2DM. IL-18 regulates cytokine secretion and the function of a number of immune cells including T-cells, neutrophils and macrophages and as such has a key role in immunity and inflammation. Pro-inflammatory monocytes exhibiting elevated cytokine secretion are closely associated with inflammation in T2DM, however, little is known about the role of leptin in modifying monocyte IL-18 secretion. We therefore aimed to investigate the effect of leptin on IL-18 secretion by monocytes. We report herein that leptin increases IL-18 secretion in THP-1 and primary human monocytes but has no effect on IL-18mRNA. Leptin and LPS signalling in monocytes occurs by overlapping but distinct pathways. Thus, in contrast to a strong stimulation by LPS, leptin has no effect on IL-1ßmRNA levels or IL-1ß secretion. In addition, LPS stimulates the secretion of IL-6 but leptin did not whereas both treatments up regulate IL-8 secretion from the same cells. Although leptin (and LPS) has a synergistic effect with exogenous ATP on IL-18 secretion in both THP-1 and primary monocytes, experiments involving ATP assays and pharmacological inhibition of ATP signalling failed to provide any evidence that endogenous ATP secreted by leptin-stimulated monocytes was responsible for enhancement of monocyte IL-18 secretion by leptin. Analysis of the action of caspase-1 revealed that leptin up regulates caspase-1 activity and the effect of leptin on IL-18 release is prevented by caspase-1 inhibitor (Ac-YVAD-cmk). These data suggest that leptin activates IL-18 processing rather than IL-18 transcription. In conclusion, leptin enhances IL-18 secretion via modulation of the caspase-1 inflammasome function and acts synergistically with ATP in this regard. This process may contribute to aberrant immune responses in T2DM and other conditions of hyperleptinemia.

A review of the evidence for pathogenic mechanisms that may link periodontitis and diabetes.

AIMS: To review the evidence for the molecular and cellular processes that may potentially link periodontal disease and diabetes. The pathogenic roles of cytokines and metabolic molecules (e.g. glucose, lipids) are explored and the role of periodontal bacteria is also addressed. Paradigms for bidirectional relationships between periodontitis and diabetes are discussed and opportunities for elaborating these models are considered. METHODS: Database searches were performed using MeSH terms, keywords, and title words. Studies were evaluated and summarized in a narrative review. RESULTS: Periodontal microbiota appears unaltered by diabetes and there is little evidence that it may influence glycaemic control. Small-scale clinical studies and experiments in animal models suggest that IL-1ß, TNF-α, IL-6, OPG and RANKL may mediate periodontitis in diabetes. The AGE-RAGE axis is likely an important pathway of tissue destruction and impaired repair in diabetes-associated periodontitis. A role for locally activated pro-inflammatory factors in the periodontium, which subsequently impact on diabetes, remains speculative. CONCLUSION: There is substantial information on potential mechanistic pathways which support a close association between diabetes and periodontitis, but there is a real need for longitudinal clinical studies using larger patient groups, integrated with studies of animal models and cells/tissues in vitro.

What do individuals with visual impairment need and want from a dialogue-based digital assistant?

CLINICAL SIGNIFICANCE: Optometrists are well-placed to provide helpful advice and guidance to patients with visual impairment but may not know how best to do this. The availability of a reliable and comprehensive conversational agent to which patients could be directed would be a valuable supplement to clinical intervention. BACKGROUND: The Artificial Intelligence in Visual Impairment (AIVI) Study is a proof-of-concept study to investigate whether ongoing information support for people with visual impairment (VI) can be provided by a dialogue-based digital assistant. The phase of the AIVI Study reported here explored the different dimensions of the information-seeking behaviour of individuals with VI: in particular, their need for information, the methods for obtaining it at present, and their views on the use of a digital assistant. METHODS: Qualitative data were collected from 120 UK-resident adults who responded to an online survey who were either visually impaired (86.7%), a carer or family member of someone with VI (5.8%), or a professional involved in the support of those with VI (7.5%). In addition, 10 in-depth 1:1 semi-structured interviews explored opinions in more detail. Thematic analysis was used to analyse the findings. RESULTS: Analysis of information needs identified 7 major themes: ocular condition; equipment, technology and adaptations; daily activities; registration; finance/employment; emotional support; and support for the carer. Participants used a wide variety of methods to access information from many sources and explained the barriers to access. Participants accepted the merit of a dialogue system aiding in a goal-directed search for specific information, but expressed reservations about its abilities in other areas, such as providing emotional support. CONCLUSIONS: Participants highlighted potential benefits, limitations, and requirements in using a digital assistant to access information about VI. These findings will inform the design of dialogue systems for populations with VI.

How has research into cytokine interactions and their role in driving immune responses impacted our understanding of periodontitis?

OBJECTIVE: To review current knowledge on cytokine interactions and the cytokine-mediated links between innate and adaptive immunity that are relevant to the pathophysiology of periodontitis. MATERIALS AND METHODS: A structured review of the literature was undertaken to identify relevant research publications using a Medline search from 1950 to September 2010. The focus of the search was on the functional role of cytokines, i.e. their actions and responses relevant to the pathogenesis of periodontal disease rather than more descriptive studies of their expression in tissues and body fluids. It was not possible to conduct a traditional systematic review with a focussed question due to the heterogeneity of published research. RESULTS: There is enormous heterogeneity in the periodontal literature in terms of experimental approaches. We have the deepest understanding of the role of the pro-inflammatory cytokines [e.g. interleukin (IL)-1ß, tumour necrosis factor-α, IL-6] with accumulating data on T-cell regulatory cytokines (e.g. IL-12, IL-18), chemokines and cytokines which mediate bone cell development and function (e.g. receptor activator of NF-κB ligand, osteoprotegerin). It is clear that there are multiple, overlapping and complex functional links between cytokines with regulatory control exerted at a number of levels and involving numerous cell types (both immune cells and resident cells in the periodontium). CONCLUSION: Cytokines appear to interact functionally in networks in the periodontium and integrate aspects of innate and adaptive immunity. However, our understanding is far from complete, particularly how molecular and cellular pathways relate to disease pathogenesis. We should adopt consistent experimental approaches to gain better insight into the totality of cytokine networks and how they drive immune responses in the periodontium.

Impact of diabetes and periodontal status on life quality.

OBJECTIVES: To investigate impact of periodontal status on quality of life (QoL) in type-1 (T1D) and type-2 (T2D) diabetes patients pre- and post-periodontal treatment using the Well-being Questionnaire 12 (W-BQ12) and Audit of Diabetes-Dependent Quality of Life-19 (ADDQoL-19). METHODS: W-BQ12 and ADDQoL-19 were self-completed by 56 T1D and 77 T2D patients at baseline and by those with periodontitis 3 and 6-months after therapy. RESULTS: At baseline, T1D patients had significantly higher general W-BQ12 [Median (IQR); 24.00 (20.25-27.75)] and positive well-being scores [8.00 (6.00-9.00)] (indicating better QoL) compared to T2D patients [22.00 (15.50-26.00) and 6.00 (3.50-9.00)], respectively (p < 0.05). Within both groups, general W-BQ12 scores did not differ significantly between patients with periodontal health, gingivitis, or periodontitis (p > 0.05). Significantly higher general W-BQ12 scores were observed in T1D patients at month 3 [28.00 (22.00-29.50)] compared to baseline [22.00 (17.00-24.50)] (p < 0.01), suggesting an initial improvement in QoL post-treatment. ADDQoL-19 identified that diabetes had greatest impact on the domain 'freedom to eat', with participants placing most importance on 'family life'. No significant changes in ADDQoL-19 scores were seen post-treatment (p > 0.05). CONCLUSIONS: Diabetes had impacts upon aspects of life quality in both T1D and T2D patients, though any additional impact based on periodontal status was not observed when using W-BQ12 and ADDQoL-19.

Expression and regulation of interleukin-33 in human monocytes.

Interleukin-33 (IL-33) is an IL-1 family cytokine that has a role in regulating T helper type 2 cytokines and mast cell development. Expression of IL-33 is also associated with chronic inflammatory conditions such as rheumatoid arthritis. However, there is little information regarding IL-33 in myeloid cell immune responses, which are important in immunity and inflammation. We therefore investigated the expression, intracellular location and regulation of myeloid cell IL-33 by lipopolysaccharide (LPS) from Escherichia coli and the periodontal pathogen Porphyromonas gingivalis. We detected IL-33 messenger RNA in the human promonocytic cell line THP-1, in monocytes derived from these cells and in primary human monocytes. However, IL-33 was not expressed in primary monocyte-derived dendritic cells. Stimulation of monocytes with E. coli LPS (Toll-like receptor 4 agonist) and LPS from P. gingivalis (Toll-like receptor 2 agonist) up-regulated IL-33 at both the messenger RNA and protein levels but IL-1beta and tumour necrosis factor-alpha had no effect. The IL-33 protein was mainly found in the cytoplasm of monocytes with no evidence of nuclear translocation in stimulated cells. Furthermore, no IL-33 secretion was detected after stimulation with LPS and/or ATP. These data indicate that the function, if any, of IL-33 in activated monocytes is primarily intracellular. Interestingly, immunofluorescence analysis indicated that IL-33 was sequestered in the nucleus of monocytes undergoing apoptosis but released into the extracellular milieu by LPS-stimulated cells in which necrosis had been induced by freeze-thawing. Therefore, this endorses the view that IL-33 may function as an 'alarmin' and have a role in signalling cellular damage and inflammatory disease pathogenesis through release from damaged or necrotic cells.

A Prototype Antibody-based Biosensor for Measurement of Salivary MMP-8 in Periodontitis using Surface Acoustic Wave Technology.

Periodontitis is an economically important disease which is highly prevalent worldwide. Current diagnostic approaches are time-consuming and require interpretation of multiple aspects of clinical and radiographic assessment. Chair-side monitoring of inflammatory mediators of periodontitis could provide immediate information about disease activity, which can inform patient management. We aimed to develop a novel prototype biosensor to measure salivary matrix metalloproteinase-8 (MMP-8) using specific antibodies and surface acoustic wave (SAW) technology. The analytical performance of the prototype biosensor was compared to standard enzyme-linked immunosorbent assay (ELISA) using unstimulated saliva samples obtained from patients with periodontitis before and after non-surgical treatment (N = 58), patients with gingivitis (N = 54) and periodontally healthy volunteers (N = 65). Receiver operator characteristic (ROC) analysis for distinguishing periodontitis from health revealed an almost identical performance between the sensor and ELISA assays (area under curve values (AUC): ELISA 0.93; SAW 0.89). Furthermore, both analytical approaches yielded readouts which distinguished between heath, gingivitis and periodontitis, correlated identically with clinical measures of periodontal disease and recorded similar post-treatment decreases in salivary MMP-8 in periodontitis. The assay time for our prototype device is 20 minutes. The prototype SAW biosensor is a novel and rapid method of monitoring periodontitis which delivers similar analytical performance to conventional laboratory assays.

Leptin and Pro-Inflammatory Stimuli Synergistically Upregulate MMP-1 and MMP-3 Secretion in Human Gingival Fibroblasts.

INTRODUCTION: Gingival fibroblast-mediated extracellular matrix remodelling is implicated in the pathogenesis of periodontitis, yet the stimuli that regulate this response are not fully understood. The immunoregulatory adipokine leptin is detectable in the gingiva, human gingival fibroblasts express functional leptin receptor mRNA and leptin is known to regulate extracellular matrix remodelling responses in cardiac fibroblasts. We therefore hypothesised that leptin would enhance matrix metalloproteinase secretion in human gingival fibroblasts. METHODS AND RESULTS: We used in vitro cell culture to investigate leptin signalling and the effect of leptin on mRNA and protein expression in human gingival fibroblasts. We confirmed human gingival fibroblasts expressed cell surface leptin receptor, found leptin increased matrix metalloproteinase-1, -3, -8 and -14 expression in human gingival fibroblasts compared to unstimulated cells, and observed that leptin stimulation activated MAPK, STAT1/3 and Akt signalling in human gingival fibroblasts. Furthermore, leptin synergised with IL-1 or the TLR2 agonist pam2CSK4 to markedly enhance matrix metalloproteinase-1 and -3 production by human gingival fibroblasts. Signalling pathway inhibition demonstrated ERK was required for leptin-stimulated matrix metalloproteinase-1 expression in human gingival fibroblasts; whilst ERK, JNK, p38 and STAT3 were required for leptin+IL-1- and leptin+pam2CSK4-induced matrix metalloproteinase-1 expression. A genome-wide expression array and gene ontology analysis confirmed genes differentially expressed in leptin+IL-1-stimulated human gingival fibroblasts (compared to unstimulated cells) were enriched for extracellular matrix organisation and disassembly, and revealed that matrix metalloproteinase-8 and -12 were also synergistically upregulated by leptin+IL-1 in human gingival fibroblasts. CONCLUSIONS: We conclude that leptin selectively enhances the expression and secretion of certain matrix metalloproteinases in human gingival fibroblasts, and suggest that gingival fibroblasts may have an ECM-degrading phenotype during conditions of hyperleptinaemia (e.g., obesity, type 2 diabetes mellitus, exogenous leptin therapy).

Protein biomarkers of periodontitis in saliva.

Periodontitis is a chronic inflammatory condition of the tissues that surround and support the teeth and is initiated by inappropriate and excessive immune responses to bacteria in subgingival dental plaque leading to loss of the integrity of the periodontium, compromised tooth function, and eventually tooth loss. Periodontitis is an economically important disease as it is time-consuming and expensive to treat. Periodontitis has a worldwide prevalence of 5-15% and the prevalence of severe disease in western populations has increased in recent decades. Furthermore, periodontitis is more common in smokers, in obesity, in people with diabetes, and in heart disease patients although the pathogenic processes underpinning these links are, as yet, poorly understood. Diagnosis and monitoring of periodontitis rely on traditional clinical examinations which are inadequate to predict patient susceptibility, disease activity, and response to treatment. Studies of the immunopathogenesis of periodontitis and analysis of mediators in saliva have allowed the identification of many potentially useful biomarkers. Convenient measurement of these biomarkers using chairside analytical devices could form the basis for diagnostic tests which will aid the clinician and the patient in periodontitis management; this review will summarise this field and will identify the experimental, technical, and clinical issues that remain to be addressed before such tests can be implemented.