Metabolomics Identify Patterns Indicating Potential Biomarkers in Primary SjöGren’s Syndrome

Objectives: In search for salivary biomarkers for primary Sjögren’s syndrome (pSS), we investigated the metabolite profile of saliva from two patient groups suffering from dry mouth. A patient group with confirmed pSS and one patient group with sicca symptoms not fulfilling the pSS classification criteria (non-SS) were compared to healthy controls without sicca symptoms.
Methods: The following subjects were included: Ten patients diagnosed with pSS (53.2±13.9 years), fulfilling the American-European Consensus Group classification criteria, ten non-SS patients (51.5±10.6 years), and ten healthy controls (53.7±2.3 years). Participants had no other diseases known to cause sicca symptoms and did not use medications influencing saliva production. All non-SS patients had negative anti-SSA/SSB serum antibodies and negative salivary gland biopsies. Stimulated whole saliva (SWS) was collected according to a standardized predefined protocol and stored at -80 °C. Samples were then analyzed using a validated in-house method for global metabolomics (high performance liquid chromatography – electrospray ionization (+ and -) – high resolution mass spectrometry and a pooled quality control for signal alignment). For data processing and statistical analyzes commercially available software was used.
Results: Mean SWS was 0.7±0.4 mL/min for pSS, 1.0±0.3 mL/min for non-SS, and 1.6±0.9 mL/min for controls. There was a significant difference in salivary secretion between pSS and controls (p=0.007), and no significant difference between pSS and non-SS (p=0.591). Preliminary results employing principal component analysis plots of metabolites showed a distinct separation between pSS and non-SS, and a separation between pSS and controls, indicating different metabolite profiles for pSS vs. non-SS and for pSS vs. controls.
Conclusions: Metabolite patterns for pSS, non-SS and controls showed distinct differences, indicating a unique disease related metabolic profile for pSS. These results may pave the way for future studies identifying salivary markers for pSS.