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.

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.

Exploring changes in oral hygiene behaviour in patients with diabetes and periodontal disease: A feasibility study.

OBJECTIVE: Exploring the feasibility to understand changes in oral hygiene behaviour using the Health Action Process Approach (HAPA) model applied to qualitative research interviews in patients with diabetes and periodontitis undergoing standard periodontitis treatment. METHODS: Patients with type 1/2 diabetes and chronic periodontitis (n = 8) received standard non-surgical periodontal treatment accompanied with personalized oral hygiene instructions by a dental hygienist. Clinical indices (% bleeding on probing (BOP), probing depth (PD), clinical attachment level (CAL), % of sites with PD ≥ 5 mm, periodontal epithelial surface area (PESA) and periodontal inflammatory surface area (PISA) were recorded pre- and post-treatment. At 3 months post-treatment, patients were interviewed using a topic guide relating to oral health. A behaviour change framework was constructed from elements of the HAPA model and used directly to map interview data to evaluate oral hygiene behaviour in these patients. RESULTS: Data from this feasibility study suggest a clinical improvement in periodontal status, albeit only monitored for 3 months. Application of the HAPA model highlighted the behavioural change pathway that diabetes patients undertake before, during and after periodontal treatment. The data suggest that patients move through all elements of the motivation phase and all elements of the volition phase except for the recovery self-efficacy element. CONCLUSION: The novel approach of applying the HAPA model to qualitative research data allowed for the collection of richer data compared to quantitative analysis only. Findings suggest that, in general, patients with periodontitis and diabetes successfully manage to incorporate new oral hygiene behaviours into their daily routine.

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.

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.

Salivary cytokines in healthy adolescent girls: Intercorrelations, stability, and associations with serum cytokines, age, and pubertal stage.

Theoretically, the measurement of cytokines in saliva may have utility for studies of brain, behavior, and immunity in youth. Cytokines in saliva and serum were analyzed across three annual assessments in healthy adolescent girls (N = 114, 11-17 years at enrollment). Samples were assayed for GM-CSF, IFNγ, IL-1ß, IL-2, IL-6, IL-8, IL-10, IL-12p70, TNFα, adiponectin, and cotinine. Results revealed: (1) cytokine levels, except IFNγ and IL-10, were detectable in saliva, and salivary levels, except IL-8 and IL-1ß, were lower than serum levels; (2) salivary cytokine levels were lower in older girls and positively associated with adiponectin; (3) compared to serum levels, the correlations between salivary cytokines were higher, but salivary cytokines were less stable across years; and (4) except for IL-1ß, there were no significant serum-saliva associations. Variation in basal salivary cytokine levels in healthy adolescent girls reflect compartmentalized activity of the oral mucosal immune system, rather than systemic cytokine activity.

Lactation modifies stress-induced immune changes in laboratory rats.

Lactation and stressor exposure both influence the activity of the immune system, but the interaction of both factors on the immune defense is poorly understood. The aim was therefore to investigate in lactating Long-Evans rats the effect of social stress on aspects of cellular immunity in the blood and mesenteric lymph nodes (MLN). Acute social stress (2h) was induced in lactating and non-lactating female intruders using a confrontation model that yielded into social defeat and increased plasma corticosterone concentrations. Stress as well as lactation had marked effects on the immune system. Acute social stress caused granulocytosis, reduced lymphocyte proliferation, and cytokine production in the blood, but had no significant effects in MLN. In the blood of lactating rats, increased numbers of granulocytes and enhanced phagocytosis, but decreased B cell numbers and reduced IL-2 production was observed. However, in MLN both lymphocyte proliferation and monocyte numbers were increased in lactating rats. The effect of stress on the immune measures was often similar in lactating and non-lactating females, but a few important differences were evident: Only non-lactating animals showed an increase in blood granulocyte numbers and a decrease in IL-2 production in response to stressor exposure. Thus, during lactation, a neuroendocrine status may exist which impedes stress-induced modulations at least of some immune parameters.

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.

Adiponectin: Serum-saliva associations and relations with oral and systemic markers of inflammation.

This study addresses gaps in our understanding about the validity and utility of using salivary adiponectin to index serum adiponectin levels. Matched blood and saliva samples were collected on a single occasion from healthy adults (n=99; age 18-36 years, 53% male). Serum and saliva was assayed for adiponectin and inflammatory cytokines (IL-1ß, IL-6, IL-8, TNFα), and saliva was also assayed for markers of blood contamination (transferrin), total protein (salivary flow rate) and matrix metalloproteinase-8 (MMP-8). We examined the extent to which salivary adiponectin was associated with serum adiponectin, and the influence of potential confounders on the serum-saliva correlation, including age, sex, body mass index, and markers of inflammation, oral health, salivary blood contamination, and flow rate. Findings revealed a modest serum-saliva association for adiponectin, and strong positive associations between salivary adiponectin and salivary levels of inflammatory cytokines, MMP-8, transferrin, and total protein. By contrast, salivary adiponectin was not related to serum levels of inflammatory activity. The magnitude of the serum-saliva association was strengthened when controlling for total protein in saliva, blood leakage into oral fluid, salivary inflammatory cytokines, and MMP-8. The pattern of findings extends our understanding of salivary adiponectin and its potential use as an index of circulating adiponectin levels.

Leptin up-regulates TLR2 in human monocytes.

The adipokine leptin elicits changes in the expression of the activation markers CD40 and CD69 in PBMCs and DCs, yet its effect on PRRs remains to be elucidated. Serum leptin concentrations are elevated in obesity and T2DM, which are both diseases associated with a proinflammatory state. We therefore investigated a possible role for leptin in monocyte TLR and CD14 expression. Leptin increased TLR2 cell-surface and mRNA expression in THP-1 and primary human monocytes. In contrast, leptin had no effect on monocyte TLR4 expression in THP-1 or primary monocytes. CD14 cell-surface and mRNA expression were increased after leptin stimulation in THP-1 monocytes. However, no change in cell-surface CD14 expression was observed after leptin treatment in primary human monocytes. Leptin also up-regulated the expression of PU.1 and EGR2, transcription factors involved in myeloid cell differentiation. Additionally, leptin potentiated Escherichia coli and Porphyromonas gingivalis LPS-induced TNF-α secretion in THP-1 monocytes. In conclusion, we show that leptin and LPS differentially influence monocyte phenotype and demonstrate, for the first time, a regulatory effect of leptin on the monocyte expression of TLR2. Leptin-stimulated TLR2 expression may potentiate innate immunity and inflammation in conditions of hyperleptinemia, such as obesity and T2DM.

Validation and quality control of ELISAs for the use with human saliva samples.

Enzyme-linked immunosorbent assays (ELISAs) have proven to be a powerful tool for fast and reliable sample analysis, in both clinical diagnostics and in research. Most assays are now available for use with a range of different analytical fluids, including serum, plasma or urine. In recent years, saliva has drawn attention as a potentially valuable diagnostic fluid; however few ELISAs have been validated for use with saliva, or their validation is often incomplete. Saliva has a number of different physical characteristics than, for example, cell culture medium or serum and assuming an ELISA which works well with serum samples will also do so with saliva potentially could lead to erroneous data and conclusions. In this report, we provide a detailed protocol to validate any ELISA for use with saliva samples and show the results of validation procedures for 13 ELISAs for using saliva. Our findings suggest that the majority of ELISAs work reliably with saliva, even if the assay was not specifically designed for this biological fluid. However, we also report a few cases where recovery or intra-and inter-assay variations were unexpectedly high, emphasising the importance of performing a validation procedure for each assay before using it with saliva to ensure accurate and reliable data.