Association of salivary inflammatory biomarkers with primary Sjögren’s syndrome

Abstract

Background: Primary Sjogren’s syndrome (pSS) is an autoimmune disease that leads to salivary and lacrimal gland dysfunction. The adaptive immune response associated with T helper-2 lymphocytes appears to be altered in these patients. Therefore, the objective of this study was to determine the salivary levels of IL-6, 5 and 4 in patients with pSS when compared to a healthy control (HC) group. The secondary objectives were to study whether ILs levels in pSS patients were associated with salivary flow, patient-reported outcomes (PROMs) for xerostomia and oral health quality of life (OHIP-14), pSS classification criteria and presence of extraglandular manifestations.

Methods: A case-control study was conducted in 36 patients with pSS and 35 HCs. Cytokine levels were measured using high-sensitivity multiplex map human immunoassays. Unstimulated and stimulated whole saliva were collected and patients filled out the questionnaires. The U-Mann-Whitney test, chi-squared and Spearman correlation test were used.

Results: IL-6 was significantly higher in pSS patients than in HCs (p=0.0001). IL-6 was significantly higher in pSS patients with a positive salivary gland biopsy (p=0.04), whole stimulated saliva hyposalivation (p=0.02) and presence of musculoskeletal disorders (p=0.03). There was a non-significant positive correlation between IL-6 levels and PROMs for xerostomia (r=0.31; p=0.06) and OHIP-14 (r=0.07; p=0.68) in pSS patients. Levels of IL4 and IL5 were not detected in both pSS and HCs patients.

Conclusions: Salivary IL-6 levels were significantly associated with pSS patients and therefore, it is hypothesized that this biomarker may be useful in the diagnosis and follow-up of this disease.