Background/Purpose: Oral manifestations can be the initial indicators of systemic diseases such as Behcet’s disease (BD) and Sjogren’s syndrome (PSS). The frequency and presentation of these manifestations are highly variable. Recurrent aphthous stomatitis (RAS) closely resembles the oral ulcers seen in BD, making it challenging to differentiate between the two based on gross examination alone. Additionally, nonspecific aphthoid conditions are observed in PSS. Unlike PSS, BD lacks specific diagnostic tests such as auto-antibody detection. This study aimed to identify distinctive patterns to differentiate these three conditions using global metabolite profiling of saliva samples.

Methods: Saliva samples were obtained from 43 patients: 24 with BD, 10 with PSS, and 9 with RAS. Prior to sample collection, patients were instructed to abstain from eating, drinking, or performing oral hygiene activities for at least 90 minutes. The metabolite profiles of the saliva samples were analyzed using gas chromatography-mass spectrometry (GC/MS). Principal component analysis (PCA) and hierarchical clustering analysis (HCA) were conducted to distinguish between the BD, PSS, and RAS groups. Variable importance for projection (VIP) scores were calculated from partial least squares discriminant analysis (PLS-DA), and ANOVA tests were used to compare the abundance of metabolites across the three groups.

Results: A total of 42 metabolites were identified from saliva samples and categorized into different classes based on their chemical structures: 9 amino acids, 16 organic acids, 6 sugars and sugar alcohols, and 11 others. The PCA plot demonstrated a clear separation between the three diseases, with the first and second principal components explaining 41.6% and 39.1% of the variance, respectively (Figure 1). The HCA plot also revealed significant differences in metabolite levels among the diseases (Figure 2). Metabolites with VIP scores greater than 1, indicating discriminant potential, included malonic acid, sorbitol, pyroglutamic acid, aspartic acid, decanoic acid, hexadecanoic acid, and L-Proline. Notably, malonic acid and aspartic acid were at significantly higher levels in BD (Figure 3), while putrescine, nonanoic acid, glycine, glucose, octadecanol, malic acid, and urea were higher in PSS. RAS was characterized by higher levels of octadecanoic acid, 4-hydroxybenzoic acid, glycerol 3-phosphate, and cysteine.

Conclusion: This metabolomic analysis of salivary samples successfully identified distinct metabolic signatures for RAS, BD, and PSS. The identified metabolites have the potential to serve as biomarkers for the early diagnosis and differentiation of these conditions, providing a foundation for personalized treatment approaches. Although the underlying metabolic processes explaining the higher levels of malonic acid and aspartic acid in BD remain to be elucidated, the identified metabolite profile may offer a promising starting point as a biomarker for BD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/metabolite-profiling-of-saliva-for-the-discrimination-of-behcets-disease-sjogrens-syndrome-and-recurrent-aphthous-stomatitis/