Potential protein biomarkers for burning mouth syndrome discovered by quantitative proteomics

Comprehensive analysis of the oral microbiota and metabolome change in patients of burning mouth syndrome with psychiatric symptoms

Background

Burning mouth syndrome (BMS) is a chronic idiopathic facial pain with intraoral burning or dysesthesia. BMS patients regularly suffer from anxiety/depression, and the association of psychiatric symptoms with BMS has received considerable attention in recent years. The aims of this study were to investigate the potential interplay between psychiatric symptoms and BMS.

Methods

Using 16S rRNA sequencing and liquid chromatography-mass spectrometry (LC/MS) to evaluate the oral microbiota and saliva metabolism of 40 BMS patients [including 29 BMS patients with depression or anxiety symptoms (DBMS)] and 40 age matched healthy control (HC).

Results

The oral microbiota composition in BMS exhibited no significant differences from HC, although DBMS manifested decreased α-diversity relative to HC. Noteworthy was the discernible elevation in the abundance of proinflammatory microorganisms within the oral microbiome of individuals with DBMS. Parallel findings in LC/MS analyses revealed discernible disparities in metabolites between DBMS and HC groups. Principal differential metabolites were notably enriched in amino acid metabolism and lipid metabolism, exhibiting associations with infectious and immunological diseases. Furthermore, the integrated analysis underscores a definitive association between the oral microbiome and metabolism in DBMS.

Conclusions

This study suggests possible future modalities for better understanding the pathogenesis and personalized treatment plans of BMS.

Is burning mouth syndrome associated with stress? A meta-analysis

BACKGROUND

Some studies have shown burning mouth syndrome (BMS) as comorbid psychosocial and psychiatric disorders, and as well, pointed at stress as a major risk factor.

OBJECTIVE

The aim of this meta-analysis was to answer the following question: 'Is there an association between BMS and stress, compared to healthy controls?'

METHODS

Two reviewers searched for the effect of stress in BMS and published on five main databases and three from the grey literature. Various questionnaires and biomarkers were analysed. Of the 2489 selected articles, 30 met the inclusion criteria. Studies englobed questionnaires, such as Perceived Stress Questionnaire, Lipp Stress Symptoms Inventory, Holmes-Rahe scale, Depression, Anxiety, and Stress Scale (DASS-21), Recent Experience Test; and various biomarkers, such as cortisol, opiorphin, IgA, α-amylase and interleukins.

RESULTS

In all studies with questionnaires, stress was significantly increased in the BMS group vs. control. Patients with BMS presented 25.73% higher cortisol levels, 28.17% higher IgA levels and 40.62% higher α-amylase levels than controls. Meta-analysis found that BMS subjects presented 3.01 nmoL/L [0.53; 5.50] higher cortisol levels, 84.35 kU/L [15.00; 153.71] higher α-amylase levels, 29.25 mg/mL [9.86; 48.64] higher IgA levels and 258.59 pg/mL [59.24; 457.94] higher IL-8 levels than control. No differences were found for opiorphin concentration in ng/mL [-0.96; 2.53]. For interleukins, no differences were founded for IL-1 β, IL-2, IL-4, IL-6, IL-8, IL-10 and TNF-α.

CONCLUSION

Based on the available evidence, this meta-analysis suggests more stress factors in questionnaire-based studies, and higher levels of cortisol, α-amylase, IgA and IL-8 biomarkers in BMS subjects than controls.

Salivary biomarkers in burning mouth syndrome: A systematic review and meta-analysis

The objective of this systematic review was to evaluate which salivary biomarkers are altered in patients with burning mouth syndrome (BMS) compared to a control group (CG). A comprehensive literature search was conducted in four databases. Case-control studies evaluating salivary biomarkers in BMS patients were included. Risk of bias was assessed using the Newcastle-Ottawa tool. RevMan was used for meta-analysis. Seventeen studies were selected. The included studies collected 54 different biomarkers. Of these biomarkers, only three (cortisol, α-amylase, and dehydroepiandrosterone) were analyzed in three or more studies. Dehydroepiandrosterone obtained contradictory results among the studies. However, cortisol and α-amylase levels were found to be higher in BMS patients. Cortisol was the only biomarker which could be included for meta-analysis. Cortisol levels were significantly higher in the BMS group compared to the CG (Mean Difference = 0.39; 95% CI [0.14-0.65]; p = 0.003). In conclusion, different studies investigated salivary biomarkers in patients with BMS compared to a CG, with controversial results. Meta-analysis, confirmed by trial-sequential analysis, showed how cortisol levels were significantly higher in BMS. Cortisol emerges as an interesting salivary biomarker in BMS, but future properly designed studies are needed to evaluate its role in diagnosis and/or response to treatment.

Salivary metabolome indicates a shift in tyrosine metabolism in patients with burning mouth syndrome: a prospective case-control study

ABSTRACT

The pathophysiology of primary burning mouth syndrome (BMS) remains controversial. Targeted analyses or "omics" approach of saliva provide diagnostic or pathophysiological biomarkers. This pilot study's primary objective was to explore the pathophysiology of BMS through a comparative analysis of the salivary metabolome among 26 BMS female cases and 25 age- and sex-matched control subjects. Secondary objectives included comparative analyses of inflammatory cytokines, neuroinflammatory markers, and steroid hormones among cases and control subjects, and among BMS patients according to their clinical characteristics. Salivary metabolome, neuroinflammatory markers, cytokines, and steroids were, respectively, analysed by liquid chromatography coupled with mass spectrometry, ELISA and protease activity assay, and multiparametric Luminex method. Among the 166 detected metabolites, univariate analysis did not find any discriminant metabolite between groups. Supervised multivariate analysis divided patients into 2 groups with an accuracy of 60% but did not allow significant discrimination (permutation test, P = 0.35). Among the metabolites contributing to the model, 3 belonging to the tyrosine pathway ( l -dopa, l -tyrosine, and tyramine) were involved in the discrimination between cases and control subjects, and among BMS patients according to their levels of pain. Among the detectable molecules, levels of cytokines, steroid hormones, and neuroinflammatory markers did not differ between cases and control subjects and were not associated with characteristics of BMS patients. These results do not support the involvement of steroid hormones, inflammatory cytokines, or inflammatory neurogenic mediators in the pathophysiology of pain in BMS, whereas the observed shift in tyrosine metabolism may indicate an adaptative response to chronic pain or an impaired dopaminergic transmission.

Identification of Potential Visceral Pain Biomarkers in Colon Exudates from Mice with Experimental Colitis: An Exploratory In Vitro Study

Chronic visceral pain (CVP) is extremely difficult to diagnose, and available analgesic treatment options are quite limited. Identifying the proteins secreted from the colonic nociceptors, or their neighbor cells within the tube walls, in the context of disorders that course with visceral pain, might be useful to decipher the mechanism involved in the establishment of CVP. Addressing this question in human with gastrointestinal disorders entails multiple difficulties, as there is not a clear classification of disease severity, and colonic secretion is not easy to manage. We propose using of a murine model of colitis to identify new algesic molecules and pathways that could be explored as pain biomarkers or analgesia targets. Descending colons from naïve and colitis mice with visceral hyperalgesia were excised and maintained ex vivo. The proteins secreted in the perfusion fluid before and during acute noxious distension were evaluated using high-resolution mass spectrometry (MS). Haptoglobin (Hp), PZD and LIM domain protein 3 (Pdlim3), NADP-dependent malic enzyme (Me1), and Apolipoprotein A-I (Apoa1) were increased during visceral insult, whilst Triosephosphate isomerase (Tpi1), Glucose-6-phosphate isomerase (Gpi1), Alpha-enolase (Eno1), and Isoform 2 of Tropomyosin alpha-1 chain (Tpm1) were decreased. Most identified proteins have been described in the context of different chronic pain conditions and, according to gene ontology analysis, they are also involved in diverse biological processes of relevance. Thus, animal models that mimic human conditions in combination with unbiased omics approaches will ultimately help to identify new pathophysiological mechanisms underlying pain that might be useful in diagnosing and treating pain. PERSPECTIVE: Our study utilizes an unbiased proteomic approach to determine, first, the clinical relevance of a murine model of colitis and, second, to identify novel molecules/pathways involved in nociception that would be potential biomarkers or targets for chronic visceral pain.

Salivary characteristics in burning mouth syndrome: a systematic review

INTRODUCTION

Compare through case-control studies, the salivary characteristics of patients with and without BMS.

EVIDENCE ACQUISITION

Searches in Embase, PubMed, Web of Science, Scopus, Cochrane, and BIREME were conducted for the identification of case-controls studies reported.

EVIDENCE SYNTHESIS

Thirty-three studies were included, of which 26 articles evaluated OSB, 17 SRF, and 7 SE. Nineteen organic biomarkers showed higher levels in BMS patients, the two most indicated being α-amylase and cortisol. Ten organic biomarkers, including Tumor Necrosis Factor-alpha (TNF-α) and IL-6, showed lower levels in BMS patients. Regarding salivary flow rate (SFR), five articles indicated that BMS patients have less unstimulated SFR (uSRF)Two articles indicate that stimulated SFR (sSRF) is lower in BMS patients nevertheless, but eight did not show differences. Sialochemical analysis revealed that sodium (Na), chloride (Cl), potassium (K), sodium (Na), and calcium (Ca), showed higher levels in BMS patients according to three studies, but two studies did not establish any differences. Two study established that BMS patients have lower Mg salivary levels.

CONCLUSIONS

Qualitative salivary characteristics suggest that BMS has neuropathic, inflammatory, emotional, immune, and hormonal involvements. BMS can be associated with changes in salivary biomarkers of inflammation and oxidative stress, is related to anxiety and degree of pain.

Applications of Tandem Mass Spectrometry (MS/MS) in Protein Analysis for Biomedical Research

Mass Spectrometry (MS) allows the analysis of proteins and peptides through a variety of methods, such as Electrospray Ionization-Mass Spectrometry (ESI-MS) or Matrix-Assisted Laser Desorption Ionization-Mass Spectrometry (MALDI-MS). These methods allow identification of the mass of a protein or a peptide as intact molecules or the identification of a protein through peptide-mass fingerprinting generated upon enzymatic digestion. Tandem mass spectrometry (MS/MS) allows the fragmentation of proteins and peptides to determine the amino acid sequence of proteins (top-down and middle-down proteomics) and peptides (bottom-up proteomics). Furthermore, tandem mass spectrometry also allows the identification of post-translational modifications (PTMs) of proteins and peptides. Here, we discuss the application of MS/MS in biomedical research, indicating specific examples for the identification of proteins or peptides and their PTMs as relevant biomarkers for diagnostic and therapy.

Neuropathic and Psychogenic Components of Burning Mouth Syndrome: A Systematic Review

The pathophysiology of primary burning mouth syndrome (BMS) has been extensively debated but is poorly understood despite a large number of hypotheses attempting to explain its etiopathogenic mechanisms. The aim of the present work was to systematically review papers that could provide arguments in favour of the neuropathic and psychogenic components of primary BMS for a better understanding of the disease. This systematic review (SR) was registered in PROSPERO (CRD42021224160). The search was limited to articles in English or French from 1990 to 01 December 2020. A total of 113 articles were considered for data extraction. We divided them into four subgroups: pharmacological and nonpharmacological management studies (n = 23); neurophysiological studies (n = 35); biohistopathological studies (n = 25); and questionnaire-based studies (n = 30). Several of these studies have shown neuropathic involvement at various levels of the neuraxis in BMS with the contribution of quantitative sensory testing (QST), functional brain imaging, and biohistopathological or pharmacologic studies. On the other hand, the role of psychological factors in BMS has also been the focus of several studies and has shown a link with psychiatric disorders such as anxiety and/or depression symptoms. Depending on the patient, the neuropathic and psychogenic components may exist simultaneously, with a preponderance of one or the other, or exist individually. These two components cannot be dissociated to define BMS. Consequently, BMS may be considered nociplastic pain.

Salivary proteome of aphthous stomatitis reveals the participation of vitamin metabolism, nutrients, and bacteria

There are currently no preventative options for recurrent aphthous stomatitis, and the only available treatments are palliative. This is partly due to a poor understanding of its etiopathogenesis. In this case-control study, we characterized the salivary proteome of patients with recurrent aphthous stomatitis in the presence and absence of lesions. Through mass spectrometry-based proteomics and bioinformatics tools, we identified that the presence of oral ulcers is associated with several specific biological processes, including the metabolic pathways of vitamin B9, B12, nitrogen, selenium, and the bacterium Neisseria meningitidis. These changes occurred only in the presence of clinically visible lesions, and there were no relevant differences between patients in anatomical regions unaffected by ulcers. Additionally, using western blot and ELISA assays, we verified that carbonic anhydrase 1 (CA1) and hemoglobin subunit beta (HBB) proteins are highly expressed during the ulcerative and remission phases of recurrent aphthous stomatitis. Our results cumulatively support saliva as an indicator of the pathophysiological changes, which occur during the clinical course of lesions. From a clinical perspective, we suggest that recurrent aphthous stomatitis is a condition triggered by temporary biological changes in people with lesions.

Proteomics-Based Identification of Salivary Changes in Patients with Burning Mouth Syndrome

Burning mouth syndrome (BMS) is a chronic oral condition characterized by an intraoral burning sensation, taste alterations, and dry mouth sensations. Although a number of factors have been closely related to the appearance of the symptoms, including anxiety, depression, and sleep disturbances, the etiology of BMS remains unclear. Furthermore, currently no objective diagnostic tools exist, making its diagnosis challenging. Therefore, to contribute to the knowledge about BMS etiology and look for objective tools for its diagnosis, the present study was conducted. Thus, the aim of this study was to analyze the proteomic profile of the resting whole saliva of patients with BMS and age and sex-matched controls using two-dimensional electrophoresis. The results showed evidence of changes in saliva at the level of proteins related to important pathways such as stress (sAA), immune system (Ig), and inflammation (leukocyte elastase inhibitor). While some of our findings have been previously described others, such as the deregulation of the coiled-coin domain containing protein 25 in BMS, are presented here for the first time to our knowledge. Thus, saliva provides us with relevant information about BMS pathophysiology and could be considered a suitable biofluid for its study and/or diagnosis.

Metabolomics of Oral/Head and Neck Cancer

Oral/head and neck cancer is the sixth most common human malignancies in the world. Despite the treatment advances in surgery, chemotherapy, and radiotherapy, the patient survival has not been significantly improved in the past several decades. As a new methodological approach, metabolomics may help reveal the metabolic reprogramming mechanisms underlying head and neck cancer cell proliferation, invasion, and metastasis and may be used to identify metabolite biomarkers for clinical applications of the disease. In this chapter, we briefly review recent metabolomic applications in head and neck cancer.

Developing a research diagnostic criteria for burning mouth syndrome: Results from an international Delphi process

OBJECTIVE

To develop a beta version of a preliminary set of empirically derived research diagnostic criteria (RDC) for burning mouth syndrome (BMS) through expert consensus, which can then be taken into a test period before publication of a final RDC/BMS.

DESIGN

A 6 round Delphi process with twelve experts in the field of BMS was used. The first round formed a focus group during which the purpose of the RDC and the definition of BMS was agreed upon, as well as the structure and contents. The remaining rounds were carried out virtually via email to achieve a consensus of the beta version of the RDC/BMS.

RESULTS

The definition of BMS was agreed to be 'an intraoral burning or dysaesthetic sensation, recurring daily for more than 2 hours per day over more than 3 months, without evident causative lesions on clinical examination and investigation'. The RDC was based upon the already developed and validated RDC/TMD and formed three main parts: patient self-report; examination; and psychosocial self-report. A fourth additional part was also developed listing aspirational biomarkers which could be used as part of the BMS diagnosis where available, or to inform future research.

CONCLUSION

This Delphi process has created a beta version of an RDC for use with BMS. This will allow future clinical research within BMS to be carried out to a higher standard, ensuring only patients with true BMS are included. Further validation studies will be required alongside refinement of the RDC as trialling progresses.

Unravelling the Potential of Salivary Volatile Metabolites in Oral Diseases. A Review

Fostered by the advances in the instrumental and analytical fields, in recent years the analysis of volatile organic compounds (VOCs) has emerged as a new frontier in medical diagnostics. VOCs analysis is a non-invasive, rapid and inexpensive strategy with promising potential in clinical diagnostic procedures. Since cellular metabolism is altered by diseases, the resulting metabolic effects on VOCs may serve as biomarkers for any given pathophysiologic condition. Human VOCs are released from biomatrices such as saliva, urine, skin emanations and exhaled breath and are derived from many metabolic pathways. In this review, the potential of VOCs present in saliva will be explored as a monitoring tool for several oral diseases, including gingivitis and periodontal disease, dental caries, and oral cancer. Moreover, the analytical state-of-the-art for salivary volatomics, e.g., the most common extraction techniques along with the current challenges and future perspectives will be addressed unequivocally.

Evaluation of IL-6 levels and +3954 polymorphism of IL-1β in burning mouth syndrome: A systematic review and meta-analysis

This study evaluated IL-6 salivary levels as well as the +3954 polymorphism of IL-1β in patients with burning mouth syndrome and healthy individuals, through case-control studies. This systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We conducted this research in PubMed/MEDLINE, Cochrane Library and Web of Science databases. The risk of bias was measured based in the Newcastle-Ottawa Scale. Researches with a group of patients with burning mouth syndrome and a control group in which the presence of the +3954 polymorphism of IL-1β and/ or IL-6 salivary levels through non-stimulated saliva were evaluated to detect if this interleukin concentrations are increased in patients and if the polymorphism is a risk factor for this syndrome. We identified seven studies with total of 440 participants, 229 patients with burning mouth syndrome and 211 healthy controls, ages 24-84 years old. The female gender was predominant. Patients in the majority of studies did not present increased levels of IL-6 and the +3954 polymorphism of IL-1β is not a risk factor for this syndrome. A few studies researched biomarkers in this pathology and more investigations are required not only to identify salivary levels and the polymorphism evaluated, but also other interleukins and polymorphisms in order to clarify the etiopathogenesis of this syndrome as well as for propose new diagnostic methods and treatments.

Saliva proteomic patterns in patients with molar incisor hypomineralization

Molar incisor hypomineralization (MIH) is an endemic pediatric disease with an unclear pathogenesis. Considering that saliva controls enamel remineralization and that MIH is associated with higher saliva flow rate, we hypothesized that the protein composition of saliva is linked to disease. To test this, we enrolled 5 children aged 6-14 years with MIH showing at least one hypersensitive molar and 5 caries-free children without hypomineralization. Saliva samples were subjected to proteomic analysis followed by protein classification in to biological pathways. Among 618 salivary proteins identified with high confidence, 88 proteins were identified exclusively in MIH patients and 16 proteins in healthy controls only. Biological pathway analysis classified these 88 patient-only proteins to neutrophil-mediated adaptive immunity, the activation of the classical pathway of complement activation, extracellular matrix degradation, heme scavenging as well as glutathione -and drug metabolism. The 16 controls-only proteins were associated with adaptive immunity related to platelet degranulation and the lysosome. This report suggests that the proteaneous composition of saliva is affected in MIH patients, reflecting a catabolic environment which is linked to inflammation.

Protein Signature in Saliva of Temporomandibular Disorders Myalgia

In the last years, several attempts have been made to study specific biological markers of temporomandibular disorders (TMD). So far, no laboratory tests have been appropriately validated for the diagnosis and prognosis of these disorders. This study aimed to investigate the proteomic profile of the whole stimulated saliva of TMD myalgia patients in order to evaluate potential diagnostic and/or prognostic salivary candidate proteins which could be useful for the management of TMD. Twenty patients diagnosed with TMD myalgia according to the validated Diagnostic Criteria for TMD (DC/TMD) and 20 matched healthy pain-free controls were enrolled. Saliva samples were collected in the morning. Comparative proteomic analysis was performed with two-dimensional gel electrophoresis followed by identification with liquid chromatography–tandem mass spectrometry. Statistical analysis of the quantitative proteomics data revealed that 20 proteins were significantly altered in patients compared to controls. Among these proteins, 12 showed significantly increased levels, and 8 showed significantly decreased levels in patients with TMD myalgia compared to controls. The identified proteins are involved in metabolic processes, immune response, and stress response. This proteomic study shows that the salivary protein profile can discriminate patients with TMD myalgia from healthy subjects, but the protein signature has no correlation with the clinical features of TMD myalgia. Additional studies are needed to validate our observations in additional sample sets and to continue assessing the utility of saliva as a suitable sample for studying processes related to TMD myalgia.

UBE2C promotes the progression of head and neck squamous cell carcinoma

The development of head and neck squamous cell carcinoma (HNSCC) is a complex pathological process and many cellular and molecular events may occur. The ubiquitin conjugating enzyme E2 (UBE2C) was found to play an oncogenic role in several human cancers. However, its functional role in HNSCC tumorigenesis remains unknown. In this study, UBE2C gene expression in HNSCC was first evaluated using the data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. The connection between UBE2C gene expression and patients' survival rates of HNSCC and other human cancers was also investigated. Liquid chromatography with tandem mass spectrometry was used to identify differentially expressed proteins, including UBE2C, between UMSCC1 oral cancer cells and normal human oral keratinocytes (NHOKs). Immunohistochemistry (IHC) was used to verify the differential expression of UBE2C protein between HNSCC and adjacent control tissues. Cell cycle analysis, MTT, colony formation, Transwell migration, and Matrigel invasion assays were used to study the effect of UBE2C downregulation on the malignant phenotypes of HNSCC cells. The bioinformatic analysis of the proteins interacting with UBE2C in HNSCC cells was also performed. Based on the data obtained from the cancer databases and our in vitro studies, we found that UBE2C was overexpressed in HNSCC and patients with high UBE2C expression suffered a remarkably worse overall survival rate than those with low UBE2C expression, and a similar observation was found in a number of other human cancers. UBE2C was also found to be overexpressed in HNSCC cells versus normal human oral keratinocytes and inhibition of UBE2C expression significantly suppressed the malignant phenotypes of HNSCC cells in vitro. The bioinformatic analysis indicated that UBE2C may be involved in head and neck tumorigenesis through the mediation of important pathways such as ubiquitin mediated proteolysis, proteasome, and cell cycle. In conclusion, our results suggest that UBE2C is consistently upregulated in many human solid tumors. It promotes HNSCC progression and may serve as a potential prognostic biomarker in HNSCC. Future studies are warranted to unveil the underlying molecular pathways of UBE2C in HNSCC.

Cytokine levels and their role in the etiopathogenesis of Burning Mouth Syndrome: A systematic review

Introduction

Burning Mouth Syndrome is characterized by variable symptoms that include pain, burning and paraguesia in an otherwise healthy-appearing oral mucosa. Although the etiopathogenesis of Burning Mouth Syndrome is unknown, some studies provide evidence of subclinical inflammation leading to disrupted cytokine levels.

Aim

To investigate the expression of cytokines and role in the etiopathogenesis of Burning Mouth Syndrome.

Methods

Online databases (MEDLINE and EMBASE) were searched from November 1986 to November 2018 for case control/cross-sectional studies comparing the levels of cytokines in patients with Burning Mouth Syndrome and healthy controls.

Results

A total of eight studies were included in the current review. Four studies were of high and four studies were of moderate quality. Seven studies evaluated IL-6, out of which four showed comparable results, two showed higher levels and one study reported lower levels in Burning Mouth Syndrome patients compared to controls. Four studies assessed IL-2, out of which two reported comparable results whereas one study reported higher levels and one study reported lower levels in Burning Mouth Syndrome patients compared to controls. IL-10 levels were measured in three studies that reported no significant differences in the levels between Burning Mouth Syndrome and healthy controls.

Discussion and conclusion

The etiopathogenesis of Burning Mouth Syndrome is multifactorial. Studies have provided scientific evidence that inflammation plays a key role in Burning Mouth Syndrome pathogenesis. However, whether up-regulation or down-regulation of specific cytokines contribute to the etiopathogenesis of Burning Mouth Syndrome remains debatable. Further high-quality studies with larger sample size and assessing a wider array of cytokines are warranted in order to obtain strong conclusions.

Proteomic profiling of whole-saliva reveals correlation between Burning Mouth Syndrome and the neurotrophin signaling pathway

Burning mouth syndrome (BMS) is characterized by a spontaneous and chronic sensation of burning in the oral mucosa, with no apparent signs. The underlying pathophysiological and neuropathic mechanisms remain unclear. Here, we attempt to elucidate some of these mechanisms using proteomic profiling and bioinformatic analyses of whole-saliva (WS) from BMS patients compared to WS from healthy individuals. Qualitative and quantitative proteomic profiling was performed using two dimensional gel electrophoresis (2-DE) and quantitative mass spectrometry (q-MS). In order to improve protein visibility, 21 high abundance proteins were depleted before proteomic profiling. Quantitative proteomic analysis revealed 100 BMS specific proteins and an additional 158 proteins up-regulated by more than threefold in those with BMS. Bioinformatic analyses of the altered protein expression profile of BMS group indicated high correlations to three cellular mechanisms including the neurotrophin signaling pathway. Based on this finding, we suggest that neurotrophin signaling pathway is involved in the pathophysiology of BMS by amplifying P75NTR activity, which in turn increases neural apoptosis thereby reducing sub-papillary nerve fiber density in the oral mucosa.

Proteomics of the acid-soluble fraction of whole and major gland saliva in burning mouth syndrome patients

OBJECTIVE

In the present study the salivary proteome of burning mouth syndrome patients and healthy subjects was characterized by a top-down proteomic approach and compared to highlight possible qualitative and quantitative differences that may give suggestions about the causes of this pathology which are still unknown.

MATERIALS AND METHODS

Resting and stimulated whole saliva, stimulated parotid and submandibular/sublingual saliva samples were collected from burning mouth syndrome patients (n = 16) and age- and gender-matched healthy subjects (n = 14). An equal volume of 0.2% trifluoroacetic acid was added to each sample immediately after collection and the supernatants were analysed by liquid chromatography coupled to electrospray-ionisation mass spectrometry. Proteins and peptides were quantified using a label-free approach measuring the extracted ion current peak areas of the main salivary proteins and peptides.

RESULTS

The quantitation of the main salivary proteins and peptides revealed a higher concentration of cystatin SN in resting saliva of burning mouth syndrome patients with respect to healthy controls and no other conspicuous changes.

CONCLUSIONS

The reported data showed that the salivary protein profile was not affected, in composition and relative abundance, by the burning mouth syndrome, except for the cystatin SN, a protein up-regulated in several pathological conditions, that might be considered potentially indicative of the disease.

Protein-Based Salivary Profiles as Novel Biomarkers for Oral Diseases

The Global Burden of Oral Diseases affects 3.5 billion people worldwide, representing the number of people affected by the burden of untreated dental caries, severe periodontal disease, and edentulism. Thus, much more efforts in terms of diagnostics and treatments must be provided in the fight of these outcomes. In this sense, recently, the study of saliva as biological matrix has been identified as a new landmark initiative in the search of novel and useful biomarkers to prevent and diagnose these conditions. Specifically, saliva is a rich reservoir of different proteins and peptides and accessible due to recent advances in molecular biology and specially in targeted and unbiased proteomics technologies. Nonetheless, emerging barriers are an obstacle to the study of the salivary proteome in an effective way. This review aims at giving an overall perspective of salivary biomarkers identified in several oral diseases by means of molecular biology approaches.