Bone remodeling-associated salivary biomarker MIP-1α distinguishes periodontal disease from health

Biologic markers of failing implants

Implants are exposed to a diverse oral environment and host responses that contribute to health or disease. For the last few decades, clinicians have relied on standard clinical and radiographic findings to assess the health of implants. However, recent studies involving the pathogenesis of peri-implantitis have identified microbial species and several putative biomarkers that could aid clinicians in this diagnostic process in the near future. This article provides an overview of the microbial species involved in implant health and disease and biomarkers found in oral fluids that relate to the underlying biological phases of a failing implant.

Relationship between chemokines and dendritic cells in human chronic periodontitis

BACKGROUND

The purpose of this study was to evaluate the relationship between chemokines and dendritic cells (DCs) in human chronic periodontitis (CP).

METHODS

Gingival samples were obtained from 23 individuals with CP, and six samples of normal mucosa (NM) overlapping the third molar were used to control for the chemokine levels. Periodontal examination was conducted. Immunohistochemistry was performed for Factor XIIIa(+) and cluster of differentiation (CD)1a(+) immature DCs and CD83(+) mature DCs. Levels of the CC chemokine ligand (CCL)2, CCL3, CCL5, CCL19, CCL20, and CXC chemokine ligand (CXCL)8 were measured in gingival tissues using enzyme-linked immunosorbent assay. Inflammatory infiltrate, DCs, chemokines, classification of human CP, and clinical parameters were correlated and compared.

RESULTS

The expression of CCL2 and CCL20 was positively correlated with increased densities of CD1a(+) DCs. CCL3 and CXCL8 were positively related to the clinical attachment level. CCL3, CCL5, CCL19, and CXCL8 levels increased in the gingival samples of patients with CP compared with NM, whereas CCL20 levels increased in advanced CP compared with mild-moderate CP.

CONCLUSIONS

More CD1a(+) immature DCs are related to CCL2 and CCL20. CCL3 and CXCL8 chemokines are related to a greater severity of human CP.

Salivary biomarkers associated with gingivitis and response to therapy

BACKGROUND

Salivary biomarkers are potentially important for determining the presence, risk, and progression of periodontal disease. However, clinical translation of biomarker technology from lab to chairside requires studies that identify biomarkers associated with the transitional phase between health and periodontal disease (i.e., gingivitis).

METHODS

Eighty participants (40 with gingivitis, 40 healthy) provided saliva at baseline and 7 to 30 days later. An additional sample was collected from gingivitis participants 10 to 30 days after dental prophylaxis. Clinical parameters of gingival disease were recorded at baseline and the final visit. Salivary concentrations of interleukin (IL)-1β, IL-6, matrix metalloproteinase (MMP)-8, macrophage inflammatory protein (MIP)-1α, and prostaglandin E2 (PGE2) were measured.

RESULTS

Clinical features of health and gingivitis were stable at both baseline visits. Participants with gingivitis demonstrated significantly higher bleeding on probing (BOP), plaque index (PI), and gingival index (GI) (P ≤0.002) and a significant drop in BOP, PI, and GI post-treatment (P ≤0.001). Concentrations of MIP-1α and PGE2 were significantly higher (2.8 times) in the gingivitis group than the healthy group (P ≤0.02). After dental prophylaxis, mean biomarker concentrations did not decrease significantly from baseline in the gingivitis group, although concentrations of IL-1β, IL-6, and MMP-8 approached healthy levels, whereas MIP-1α and PGE2 concentrations remained significantly higher than in the healthy group (P ≤0.04). Odds ratio analyses showed that PGE2 concentrations, alone and in combination with MIP-1α, readily discriminated gingivitis from health.

CONCLUSIONS

Salivary PGE2 and MIP-1α discriminate gingivitis from health, and patients with gingivitis who return to clinical health continue to produce inflammatory mediators for weeks after dental prophylaxis.

Uncovering the molecular networks in periodontitis

Periodontitis is a complex immune-inflammatory disease that results from a preestablished infection in gingiva, mainly due to Gram-negative bacteria that colonize deeper in gingival sulcus and latter periodontal pocket. Host inflammatory and immune responses have both protective and destructive roles. Although cytokines, prostaglandins, and proteases struggle against microbial burden, these molecules promote connective tissue loss and alveolar bone resorption, leading to several histopathological changes, namely destruction of periodontal ligament, deepening of periodontal pocket, and bone loss, which can converge to attain tooth loss. Despite the efforts of genomics, transcriptomics, proteomics/peptidomics, and metabolomics, there is no available biomarker for periodontitis diagnosis, prognosis, and treatment evaluation, which could assist on the established clinical evaluation. Nevertheless, some genes, transcripts, proteins and metabolites have already shown a different expression in healthy subjects and in patients. Though, so far, 'omics approaches only disclosed the host inflammatory response as a consequence of microbial invasion in periodontitis and the diagnosis in periodontitis still relies on clinical parameters, thus a molecular tool for assessing periodontitis lacks in current dental medicine paradigm. Saliva and gingival crevicular fluid have been attracting researchers due to their diagnostic potential, ease, and noninvasive nature of collection. Each one of these fluids has some advantages and disadvantages that are discussed in this review.

Macrophage inflammatory protein-1α shows predictive value as a risk marker for subjects and sites vulnerable to bone loss in a longitudinal model of aggressive periodontitis

Improved diagnostics remains a fundamental goal of biomedical research. This study was designed to assess cytokine biomarkers that could predict bone loss (BL) in localized aggressive periodontitis. 2,058 adolescents were screened. Two groups of 50 periodontally healthy adolescents were enrolled in the longitudinal study. One group had Aggregatibacter actinomycetemcomitans (Aa), the putative pathogen, while the matched cohort did not. Cytokine levels were assessed in saliva and gingival crevicular fluid (GCF). Participants were sampled, examined, and radiographed every 6 months for 2-3 years. Disease was defined as radiographic evidence of BL. Saliva and GCF was collected at each visit, frozen, and then tested retrospectively after detection of BL. Sixteen subjects with Aa developed BL. Saliva from Aa-positive and Aa-negative healthy subjects was compared to subjects who developed BL. GCF was collected from 16 subjects with BL and from another 38 subjects who remained healthy. GCF from BL sites in the 16 subjects was compared to healthy sites in these same subjects and to healthy sites in subjects who remained healthy. Results showed that cytokines in saliva associated with acute inflammation were elevated in subjects who developed BL (i.e., MIP-1α MIP-1β IL-α, IL-1β and IL-8; p<0.01). MIP-1α was elevated 13-fold, 6 months prior to BL. When MIP-1α levels were set at 40 pg/ml, 98% of healthy sites were below that level (Specificity); whereas, 93% of sites with BL were higher (Sensitivity), with comparable Predictive Values of 98%; p<0.0001; 95% C.I. = 42.5-52.7). MIP-1α consistently showed elevated levels as a biomarker for BL in both saliva and GCF, 6 months prior to BL. MIP-1α continues to demonstrate its strong candidacy as a diagnostic biomarker for both subject and site vulnerability to BL.

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.

Smoking effect on chemokines of the human chronic periodontitis

AIM

Evaluate the effects of smoking on chemokines of the human chronic periodontitis (CP).

MATERIALS AND METHODS

Gingival samples were obtained from 23 smokers (S) and 20 non-smokers (NS) diagnosed with CP. Periodontal examination was performed. The CCL2, CCL3, CCL5, CCL19, CCL20, and CXCL8 chemokine levels were measured in gingival tissues using enzyme-linked immunosorbent assay. Chemokines were compared between S and NS, and were correlated with the number of cigarettes per day (C/day) and time of the smoking habit in years (SH/years).

RESULTS

CCL3 and CXCL8 of S were significantly smaller than that found in NS subjects, whereas the CCL5 levels increased in the S group. Negative correlations could be observed between CCL19 levels and SH/year.

CONCLUSION

Smoking suppresses the immune response which may contribute to an increased susceptibility to periodontal disease in smokers.

Oral fluid based biomarkers in periodontal disease: part 1. Saliva

Traditional clinical measurements such as probing pocket depth, bleeding on probing, clinical attachment loss; plaque index and radiographs used for periodontal diagnosis are often of limited usefulness as they are indicators of previous periodontal disease rather than present disease activity. A literature search was carried out to find out all the available tests that indicate periodontal disease markers in saliva. All major databases were searched to compile the information on published reports between 1999 and 2014. The list of biomarkers available to date is compiled and presented in a table format. Each biomarker is discussed separately based on the available evidence. Based on the evidence, it can be concluded that several sensitive salivary indicators of periodontitis are available to detect the presence, severity and response to treatment. Further studies are warranted to analyze the sensitivity and reliability of these indicators that might help in developing non-invasive tests that could help in the diagnosis of periodontal disease.

Salivary visfatin concentrations in patients with chronic periodontitis

BACKGROUND

Visfatin, also known as pre-B-cell colony-enhancing factor, is secreted from a variety of cells and is thought to have some proinflammatory and immunomodulating effects. It is indicated that serum/plasma levels of visfatin increase in a number of inflammatory disorders. The present study aims to evaluate salivary concentrations of visfatin in patients with chronic periodontitis (CP).

METHODS

Twenty patients with CP and 20 periodontally healthy individuals were enrolled in this study. For each patient, the values of clinical parameters, such as bleeding index, plaque index, probing depth, and clinical attachment level (CAL), were recorded. Whole saliva samples were collected, and concentrations of visfatin were evaluated using standard enzyme-linked immunosorbent assay. Statistical analysis was performed using statistical software.

RESULTS

Visfatin was detectable in all samples. Salivary visfatin concentrations were significantly higher in the periodontitis group. In addition, there was a positive significant relationship between salivary visfatin concentrations and CAL in the periodontitis group. However, no significant association was observed between salivary visfatin levels and other periodontal parameters or body mass index.

CONCLUSION

These results indicate that there is a relationship between salivary visfatin and CP; however, further studies are needed to confirm this finding.

Salivary soluble receptor activator of nuclear factor kappa B ligand/osteoprotegerin ratio in periodontal disease and health

Purpose

The receptor activator of nuclear factor kappa B (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system plays a significant role in osteoclastogenesis, activation of osteoclasts, and regulation of bone resorption. This study aimed to evaluate the use of the salivary soluble RANKL (sRANKL)/OPG ratio as a diagnostic marker for periodontitis in nonsmokers.

Methods

Twenty-five patients with chronic periodontitis and 25 individuals with a healthy periodontium were enrolled in this study. Samples containing 5 mL of unstimulated saliva were obtained from each subject. Salivary sRANKL and OPG concentrations were determined using a standard enzyme-linked immunosorbent assay. Statistical analysis was performed using SPSS ver. 18.0.

Results

The levels of sRANKL and OPG were detectable in all of the samples. Positive relationships were found between the plaque index and clinical attachment level and both the salivary concentration of sRANKL and the salivary sRANKL/OPG ratio (P<0.05). The salivary concentration of sRANKL and the sRANKL/OPG ratio were significantly higher in the periodontitis group than in the healthy group (P=0.004 and P=0.001, respectively). In contrast, the OPG concentration showed no significant differences between the groups (P=0.455).

Conclusions

These findings suggest that the salivary sRANKL/OPG ratio may be helpful in the screening and diagnosis of periodontitis. However, longitudinal studies with larger populations are needed to confirm these results.

Role of salivary epithelial toll-like receptors 2 and 4 in modulating innate immune responses in chronic periodontitis

BACKGROUND AND OBJECTIVE

Chronic periodontitis is initiated by sequential colonization with a broad array of bacteria and is perpetuated by an immune-inflammatory response to the changing biofilm. Host recognition of microbes is largely mediated by toll-like receptors (TLRs), which interact with conserved pathogen-associated molecular patterns. Based on ligand recognition, TLR-2 and TLR-4 interact with most periodontal pathogens. Extracrevicular bacterial reservoirs, such as the oral epithelial cells, contribute to the persistence of periodontitis. Human saliva is a rich source of oral epithelial cells that express functional TLRs. In this study we investigated the role of salivary epithelial cell (SEC) TLR-2 and TLR-4 in patients with generalized chronic periodontitis.

MATERIAL AND METHODS

Unstimulated whole saliva (UWS) was collected from patients with generalized chronic periodontitis and from healthy individuals after obtaining informed consent. Epithelial cells isolated from each UWS sample were assessed for TLR-2, TLR-4, peptidoglycan recognition protein (PGRP)-3 and PGRP-4 by quantitative real-time PCR. In addition, the SECs were stimulated in vitro with microbial products for up to 24 h. The culture supernatant was assessed for cytokines by ELISA.

RESULTS

Stimulation with TLR-2- or TLR-4-specific ligands induced cytokine secretion with differential kinetics and up-regulated TLR2 and TLR4 mRNAs, respectively, in cultures of SECs from patients with periodontitis. In addition, the SECs from patients with periodontitis exhibited reduced PGRP3 and PGRP4 mRNAs, the TLR-responsive genes with antibacterial properties.

CONCLUSION

SECs derived from the UWS of patients with chronic periodontitis are phenotypically distinct and could represent potential resources for assessing the epithelial responses to periodontal pathogens in the course of disease progression and persistence.

Salivary diagnostics for periodontal diseases

BACKGROUND

and Overview The use of salivary diagnostics continues to develop and advance the field of risk determination for periodontal diseases. Researchers are investigating genetic, microbial and protein biomarkers with the objective of translating findings to such aspects of clinical care as broad patient screening, monitoring and treatment planning.

METHODS

/st> In this review, the author briefly explores currently available salivary diagnostics used to identify bacteria prevalent in periodontal disease, and focuses on the future development and use of a variety of rapid disease detection platforms, such as lab-on-a-chip, as a point-of-care device for identification of patients' risk.

CONCLUSIONS

and

CLINICAL IMPLICATIONS

/st> Several diagnostic tests are commercially available, and point-of-care tests are under development. However, challenges remain regarding the introduction of these technologies to clinical practice and adoption by dental practitioners for promotion of personalized oral health care.

Evaluation of salivary biomarker profiles following non-surgical management of chronic periodontitis

OBJECTIVES

Soluble toll-like receptor-2 (sTLR-2) and cytokines in saliva were assessed as clinical markers for chronic periodontitis in a longitudinal study.

MATERIALS AND METHODS

Unstimulated whole saliva was collected from 20 periodontally healthy individuals and 20 patients with chronic periodontitis at diagnosis and at 1 and 6 weeks following scaling and root planing (SRP). Biomarkers including the cytokines (IL-4, IL-6, IL-10, and IL-17), sTLR-2, and sCD14 in saliva were measured by enzyme-linked immunosorbent assay. Mann-Whitney U-test and Student's t-test were used to determine the significance between healthy and chronic periodontitis groups and that between pre- and post-SRP samples, respectively.

RESULTS

Salivary sTLR-2, IL-17, and IL-10 levels were significantly lower and those of sCD14, IL-6, and IL-4 were significantly higher in patients with chronic periodontitis as compared with healthy controls. Furthermore, sTLR-2 and IL-4 in saliva reached levels comparable to those of healthy individuals at 6-week re-evaluation visit, implicating a correlation of the two markers with the disease process.

CONCLUSIONS

Our data suggest that salivary sTLR-2 is a potential prognostic or maintenance marker for chronic periodontitis. The observed variability of salivary cytokines is consistent with the role of these cytokines in the progression of chronic periodontitis.

Salivary biomarker development using genomic, proteomic and metabolomic approaches

The use of saliva as a diagnostic sample provides a non-invasive, cost-efficient method of sample collection for disease screening without the need for highly trained professionals. Saliva collection is far more practical and safe compared with invasive methods of sample collection, because of the infection risk from contaminated needles during, for example, blood sampling. Furthermore, the use of saliva could increase the availability of accurate diagnostics for remote and impoverished regions. However, the development of salivary diagnostics has required technical innovation to allow stabilization and detection of analytes in the complex molecular mixture that is saliva. The recent development of cost-effective room temperature analyte stabilization methods, nucleic acid pre-amplification techniques and direct saliva transcriptomic analysis have allowed accurate detection and quantification of transcripts found in saliva. Novel protein stabilization methods have also facilitated improved proteomic analyses. Although candidate biomarkers have been discovered using epigenetic, transcriptomic, proteomic and metabolomic approaches, transcriptomic analyses have so far achieved the most progress in terms of sensitivity and specificity, and progress towards clinical implementation. Here, we review recent developments in salivary diagnostics that have been accomplished using genomic, transcriptomic, proteomic and metabolomic approaches.