Primary Sjögren's syndrome (pSS) is one of the most prevalent systemic autoimmune diseases characterised by inflammation and tissue damage of exocrine glands, especially salivary or lacrimal gland. IL-17 related immune response is pathogenic with proinflammatory feature in pSS. However, whether IL-17E, an IL-17 family member, is involved in pSS pathogenesis or not, has not been determined.
Serum levels of IL-17E and IL-17A as comparison in 107 patients with pSS and 42 healthy controls were determined with multiplex cytokine assays. EULAR Sjögren's syndrome disease activity index (ESSDAI) score was calculated. Laboratory parameters were measured by standard laboratory techniques. The inflammatory infiltration of minor labial gland biopsies was graded based on numbers of lymphocyte and quantified by Focus Score (FS). Expression of IL-17E and IL-17A in the biopsy was evaluated with immunohistochemistry.
Significantly elevated IL-17E in pSS patients associated with ESSDAI, haematologic disorders and autoantibody production, including anti-nuclear antibodies (ANA), rheumatoid factor (RF) and anti-SSA antibodies were found. Histopathological features showed that expression of IL-17E was found in labial salivary gland and correlated with lymphocytic infiltration.
IL-17E expression in pSS patients was increased and associated with haematologic disorders, autoantibody production and lymphocytic infiltration in salivary gland. This finding indicated that IL-17E is involved in pSS pathogenesis.