Metabolomics:Open Access

Metabolic Profiling of Saliva in Patients with Primary Sjögren’s Syndrome

Abstract

Jopi JW Mikkonen, Maria Herrala, Pasi Soininen, Reijo Lappalainen, Leo Tjäderhane, Hubertus Seitsalo, Raija Niemelä, Tuula Salo, Arja M Kullaa and Sami Myllymaa

Objective: To investigate the feasibility of 1 H-NMR spectroscopy for metabolic profiling of human saliva samples and to determine whether the concentration of certain salivary metabolites, mainly representing small organic acids and amino acids, differ between patients with primary Sjögren´s syndrome (pSS) and healthy controls. Methods: Stimulated whole-mouth saliva (SWMS) was collected from female pSS patients (n =15, all fulfilling the revised European Community proposed criteria). Salivary flow rate was immediately determined, samples were then frozen and subsequently analyzed by 1 H-NMR spectroscopy in comparison with samples collected from healthy individuals (n=15). Results: From each sample, up to 24 metabolites could be identified and quantified. Choline and taurine concentrations were very significantly higher in the pSS patients compared to healthy controls (p<0.001), but their concentrations correlated negatively with salivary flow rate. Alanine and glycine concentrations were significantly higher (p=0.004, p=0.007, respectively), whereas butyrate (p= 0.034), phenylalanine (p=0.026) and proline (p=0.032) were only slightly higher in pSS saliva samples than in controls. Conclusions: NMR spectroscopy has a potential for quantitative metabolic profiling of saliva samples. NMR spectroscopy is suitable for the analysis of NAAs in saliva and it can bypass the other methods, which are normally suitable for analysis of just one metabolite.