IL-35, TNF-α, BAFF, and VEGF serum levels in patients with different rheumatic diseases

OBJECTIVES: Inflammatory processes in rheumatic diseases spread via various types of immune system cells and tissues with the aid of inflammatory cytokines and growth factors and the participation of vascular endothelium. Research is still conducted to determine the role of individual factors in the pathophysiology of rheumatic diseases. The task is complicated because the multiplane network of cytokines is characterized by complex correlations manifesting as positive and negative feedback, which impedes the definitive interpretation of the role of specific cytokines. Therefore, it seems justified to perform a comparative analysis of the expression of at least several molecules in one study, which may help reveal their role in the pathogenesis of rheumatic diseases and have prognostic value. MATERIAL AND METHODS: The aim of the study involves the assessment and comparative analysis of the concentrations of interleukin 35 (IL-35), tumour necrosis factor α (TNF-α), B-cell-activating factor (BAFF), and vascular endothelial growth factor (VEGF) in peripheral blood serum in patients with rheumatoid arthritis (RA) (n = 43), systemic lupus erythematosus (SLE) (n = 28), antiphospholipid syndrome (APS) (n = 24), and mixed connective tissue disease (MCTD) (n = 9). The main intention is to search for biomarkers for specific rheumatic diseases. Cytokine and growth factor levels were determined using specific ELISA kits. RESULTS: Statistically significant differences in VEGF and IL-35 concentrations occurred between patients with APS vs. RA and SLE vs. RA. There was a significant high positive correlation between the concentration of BAFF and TNF-α (r = 0.77, p < 0.0000) in patients with APS, as well as in patients with SLE (r = 0.55, p = 0.00). CONCLUSIONS: BAFF and TNF-α may be promising biomarkers in patients with APS and VEGF in patients with RA. Additionally, IL-35 may be a useful marker for the diagnosis of APS. Positive correlation of BAFF and TNF-α concentrations in APS and SLE potentially indicates much more similar etiopathogenesis of these diseases than it could be previously predicted.