Chemokine saliva levels in patients with primary Sjögren's syndrome, associated Sjögren's syndrome, pre-clinical Sjögren's syndrome and systemic autoimmune diseases.
To assess the saliva levels of CXCL13, CXCL10, CCL2, CCL3, CXCL12 and CCL5 in patients with primary SS (pSS), patients with associated SS (aSS), patients with systemic autoimmune disease (SAD) without SS, pre-clinical SS and healthy controls. We included 44 patients with pSS (Group A), 30 with aSS (Group B), 49 with SAD without SS (Group C), 14 patients with SAD and focal lip infiltrates, but who do not fulfil SS criteria (Group D, pre-clinical SS) and 32 healthy controls (Group E). Saliva samples were collected and analysed for chemokine levels by luminometry. We used descriptive statistics and the Mann-Whitney U-test and Kruskall-Wallis test. All the studied chemokines were found at low concentration in controls with the exception of CCL2. Patients with pSS had higher levels CXCL10 and CCL2 than controls (P = 0.05). However, they had similar levels of CXCL13, CCL5, CXCL12, CCL2 and CXCL10 than patients with aSS and SAD without SS. Patients with pre-clinical SS had higher levels of CXCL10 than patients with pSS (P = 0.03), aSS (P = 0.04) and controls (P = 0.001). CCL2 levels were higher in all patients with an autoimmune background when compared with controls (P < 0.05 for each comparison). We found no difference in salivary chemokines between patients neither with pSS or aSS nor in patients with SAD. CCL2 and CXCL10 were increased in all patients with an autoimmune background. CXCL10 was notably increased in pre-clinical SS, suggesting it could be an early inflammatory salivary biomarker.