Background Sjogren syndrome (SS) is a chronic, multisystemic autoimmune disease characterized by lymphoplasmocytic infiltration of the salivary. Until now, its pathogenesis and diagnosis remain enigmatic. As a multisystem disease, it involves joints, hematology, lymphocyte organ, pulmonary, kidney, liver and other organs. Different organ involvements evolve from differential impression of genes and proteins.
Objectives To identify gene expression profile in peripheral blood mononuclear cell (PBMC)of patients with Sjogren's syndrome (SS) compare it to healthy volunteers, and then verify serum protein level of identified genes in peripheral blood and analyze the correlation between level of those serum protein and disease activity parameters.
Methods SS patients with leucopenia and 3healthy volunteers were included.The cRNA probes prepared for total RNA were hybridized with three identical gene chips.The difference of gene expression of each patient and volunteers were compared. According to statistical analysis and pathway analysis, different expression genes were identified. Serum protein levels of two different expressed genes weredetected by enzyme-linked immunosorbent assay (ELISA) in 40 SS patients, 40 Rheumatoid arthritis (RA) patients, 24 Osteoarthritis (OA) patients and 40 healthy controls. Independent sample t-test was applied. Correlation analysis was done to investigate the relationship between two serum protein levels and disease activity parameters of SS, including number of white blood cells, organ involvement, ESSDAI score, levels of ESR, C-reactive protein (CRP), Rheumatoid Factor (RF), immunoglobin G (IgG), immunoglobin A (IgA) and immunoglobin M (IgM).
Results Significant difference in the expression of 82 genes could be detected between patients and volunteers. Among these,45 were upregulated, and 37 were downregulated. Statistical difierence was calculated between patients and volunteers especially in the following two pathways: the complement and coagulation pathways (including C2, PROS1, F2R and SEPPING1) and the cytokine-cytokine receptor interaction pathway (including FASLG, MPL, CCL20 and CXCL2) (P<0.01).Further study identified that CXCL2, CCL20 levels were significantly higher in SS patients than in healthy controls (P<0.01). CCL20 level was significantly correlated with number of white blood cells and level of CRP, while negatively with pulmonary interstitial diseases, and positive correlation was observed between CXCL2 level andnumber of white blood cells.
Conclusion This study has identified distinct gene expression profiles in PBMC from patients with SS patients with hematology involvement and healthy volunteers. Among which, CXCL2 and CCL20 play a part in the development of SS and their determination may benefit evaluation of disease activity.
Disclosure of Interest None declared