Global salivary metabolite profiling by GC/MS provides distinct metabolic signatures enabling discrimination among BD, PSS, and RAS, with malonic acid and aspartic acid significantly elevated in BD compared to PSS and RAS, suggesting their diagnostic potential.
Key Findings
Results
Salivary metabolite profiling by GC/MS successfully discriminated among Behcet's disease, Sjogren's syndrome, and recurrent aphthous stomatitis.
Saliva samples were collected from 43 patients total: BD (n=24), PSS (n=10), and RAS (n=9)
Samples were collected after fasting and abstaining from oral activities for at least 90 minutes
Gas chromatography-mass spectrometry (GC/MS) was employed for metabolite profiling
Principal component analysis (PCA) and hierarchical clustering analysis (HCA) demonstrated clear discrimination among all three groups
Results
Forty-two metabolites were identified and categorized across multiple chemical classes in saliva samples.
Metabolites were categorized into amino acids, organic acids, sugars, sugar alcohols, and others
PLS-DA was used to calculate variable importance in projection (VIP) scores for each metabolite
Metabolites with VIP > 1 included malonic acid, sorbitol, pyroglutamic acid, aspartic acid, decanoic acid, hexadecenoic acid, and L-proline
ANOVA was applied to compare metabolite abundance across the three disease groups
Results
Malonic acid and aspartic acid were significantly elevated in Behcet's disease compared to both Sjogren's syndrome and recurrent aphthous stomatitis.
Both malonic acid and aspartic acid had VIP scores > 1, indicating importance in group discrimination
The elevation of these metabolites was observed specifically in BD relative to PSS and RAS
The authors describe these findings as suggesting 'diagnostic potential' for distinguishing BD from the other conditions
These metabolites belong to the organic acids and amino acids categories, respectively
Background
Recurrent aphthous stomatitis clinically mimics Behcet's disease ulcers, motivating the need for objective discriminatory biomarkers.
Oral manifestations can be the initial sign of systemic diseases such as BD and PSS
The frequency and morphology of oral lesions vary widely across these conditions
Nonspecific aphthoid lesions are also seen in PSS, further complicating clinical differentiation
Differentiation on clinical grounds alone is described as complicated
Conclusions
Salivary metabolomics using GC/MS may enhance understanding of oral mucosal manifestations in systemic autoimmune diseases.
The study demonstrates that global salivary metabolite profiling can produce 'distinct metabolic signatures' for each disease group
The approach is non-invasive, using saliva as the biological matrix
The authors suggest this methodology may have broader implications for understanding systemic autoimmune diseases with oral manifestations
Both unsupervised (PCA, HCA) and supervised (PLS-DA) multivariate analyses were consistent in separating the disease groups
What This Means
This research suggests that the chemical composition of saliva can be used to tell apart three conditions that cause painful mouth sores: Behcet's disease (an inflammatory disorder), Sjogren's syndrome (an autoimmune disease affecting moisture-producing glands), and recurrent aphthous stomatitis (common canker sores). Because these conditions look very similar in the mouth, doctors often find it difficult to diagnose them based on appearance alone. The researchers collected saliva from 43 patients across the three groups and used a technique called gas chromatography-mass spectrometry to identify and measure 42 different small molecules (metabolites) present in the saliva. Statistical analyses of these molecules clearly separated the three patient groups from one another.
The study found that two specific molecules — malonic acid and aspartic acid — were significantly higher in the saliva of Behcet's disease patients compared to the other two groups. Several other molecules, including sorbitol, pyroglutamic acid, decanoic acid, hexadecenoic acid, and L-proline, also contributed meaningfully to distinguishing between the groups. These chemical differences suggest that the underlying biology of these three conditions, even at the level of the mouth, is distinct enough to be measurable in saliva.
This research suggests that a saliva test based on metabolite profiling could one day help clinicians more accurately and quickly diagnose these conditions, potentially reducing the delay between symptom onset and correct treatment. The sample sizes in this study were small, so larger validation studies would be needed before such a test could be used clinically, but the findings represent a promising step toward non-invasive, objective diagnostic tools for diseases that are currently difficult to differentiate.
Kim S, Zhang M, Ahn J, Hwang J. (2026). Metabolite profiling of saliva for the discrimination of Behcet's disease, Sjögren's syndrome, and recurrent aphthous stomatitis.. PloS one. https://doi.org/10.1371/journal.pone.0351403