Identification of novel serum proteins that distinguish idiopathic recurrent aphthous stomatitis from Behcet's disease.

Recurrent aphthous stomatitis (RAS) is a chronic autoinflammatory condition marked by recurring, painful sores in the mouth. It is often confused with Behcet's disease (BD), a rare systemic vasculitis that also presents with oral ulcers. Despite overlapping symptoms, BD has broader systemic implications, making an accurate diagnosis critical. This study aims to identify unique serum proteins that could reliably distinguish idiopathic RAS from BD. We reanalyzed our previous mass spectrometry dataset comprising blood samples from 12 BD patients, 12 individuals with idiopathic RAS, and 21 healthy controls. Differentially expressed proteins (DEPs) related to RAS were identified and examined through Kyoto Encyclopedia of Genes and Genomes and Gene Ontology pathway enrichment. A protein-protein interaction (PPI) network was created to explore functional connections among the DEPs. Validation of three RAS-related proteins was carried out using enzyme-linked immunosorbent assay (ELISA) in a separate cohort of 26 RAS patients, 26 BD patients, and 30 healthy individuals. Their diagnostic utility was then evaluated via receiver operating characteristic (ROC) curve analysis. A total of 99 proteins showed differential expression in RAS samples but not in BD cases when compared to healthy controls-85 were upregulated, and 14 were downregulated. Enrichment analyses indicated these proteins are primarily involved in metabolic and infection-related pathways, particularly influencing keratinocyte differentiation and oxidative stress responses. PPI network analysis highlighted key metabolic and keratinocyte-related proteins as central hubs, suggesting a role in RAS pathology. ELISA validation confirmed significantly elevated levels of ANXA2, ENO1, and S100A7 in RAS patients compared to both BD patients and healthy subjects. Our findings identify a set of RAS-related serum proteins with potential diagnostic value. These serum proteins may enhance the clinical differentiation of RAS from BD, aiding in more accurate and timely patient care.