Serum levels of TNF-α, sIL-2R, IL-6, and IL-8 are increased and associated with elevated lipid peroxidation in patients with Behcet's disease

AIM Behcet's disease (BD) is a systemic immunoinflammatory disorder and the aetiopathogenesis is to be specified. Cytokines play a role in immune response and in many inflammatory diseases. The aim of this case-control study is to investigate serum pro-inflammatory cytokine tumour necrosis factor (TNF)-alpha, interleukin-1beta (IL-1beta), soluble IL-2 receptor (sIL-2R), IL-6, and chemokine IL-8 levels in patients with BD. We also determined the end product of lipid peroxidation (malondialdehyde (MDA)) in BD patients as an index for oxidative stress. Methods: A total of 37 patients (19 men, 18 women) with BD (active, n = 17; inactive, n = 20) and 20 age-matched and sex-matched healthy control subjects (11 men, nine women) included in this cross-sectional, blinded study. Serum TNF-alpha, IL-1beta, sIL-2R, IL-6 and IL-8 levels were determined by a spectrophotometer technique using the immulite chemiluminescent immunometric assay. Lipid peroxidation was evaluated by Wasowicz et al. The levels of cytokines and lipid peroxidation in the active period were compared with the inactive period of the disease. Results are expressed as mean +/- standard error. Results: IL-1beta levels were below the detection limits of the assay (< 5 pg/ml) in all samples. Mean levels of MDA (8.1 +/- 0.7 μmol/l), sIL-2R (800 +/- 38 U/ml), IL-6 (12.6 +/- 1.1 pg/ml), IL-8 (7.2 +/- 0.4 pg/ml), and TNF-α (7.9 +/- 0.5 pg/ml) in active BD patients were significantly higher than those in inactive patients (4.3 +/- 0.5 μmol/l, p < 0.01; 447 +/- 16 U/ml, p < 0.001; 8.3 +/- 0.6 pg/ml, p = 0.006; 5.3 +/- 0.1 pg/mL p < 0.001; and 5.1 +/- 0.2 pg/ml, p < 0.001; respectively) or control subjects (2.1 +/- 0.2 μmol/l, p < 0.001; 446 +/- 20 U/ml, p < 0.001; 6.4 +/- 0.2 pg/ml, p < 0.001; 5.4 +/- 0.1 pg/ml, p < 0.001; and 4.7 +/- 0.1 pg/ml, p < 0.001, respectively). On the contrary, only the mean IL-6 level was significantly different between inactive BD and control subjects (p = 0.02). All acute phase reactants were significantly higher in active BD than in inactive period (for each,p < 0.01). Conclusions: High levels of sIL-2R, IL-6, IL-8 and TNF-α indicate the activation of immune system in BD. Serum sIL-2R, IL-6, IL-8 and TNF-α seem to be related to disease activity. Increased lipid peroxidation suggests oxidative stress in BD and therefore tissue damage in such patients. Amelioration of clinical manifestations would be envisaged by targeting these cytokines, chemokines and lipid peroxidation with pharmacological agents.