The association of cytokines with disease activity and damage scores in systemic lupus erythematosus patients

Objective: The aim of this study was to explore the role of cytokines in the pathogenesis of SLE in a genetically homogeneous Caucasian SLE patient population.

Methods: Serum levels of the following cytokines were determined by ELISA in SLE patients (diagnosed as per ACR diagnostic criteria): IL-1β, IL-10, IL-12p70 and TNF-α. Demographic data, disease activity as per the SLEDAI and damage scores (SLICC) at the 5-year follow-up were calculated.

Results: Enhanced production of TNF-α, IL-1 and IL-10 were observed in SLE patients compared with controls. A strong positive correlation was seen between levels of IL-12p70 and IL-10. In addition, IL-10, TNF-α and IL-1 demonstrated a significant relationship with disease activity. Interestingly, elevated levels of IL-10 were observed in SLE patients with CNS involvement while patients with elevated levels of TNF-α were more likely to have renal involvement and sustain damage over the follow-up period. Additionally, the ratio of all cytokines assayed to IL-12p70 levels were significantly higher in SLE patients when compared with controls, with an association seen between damage accrual and the IL-1β/IL-12p70 ratio (r = 0.431, P = 0.003), IL-10/IL-12p70 ratio (r = 0.351, P = 0.018) and TNF-α/IL-12p70 ratio (r = 0.33, P = 0.028). When the respective ratios were analysed for organ-specific disease, significant differences were observed for the IL-1β/IL-12p70 ratio (0.79 vs 0.47, P = 0.036), IL-10/IL-12p70 ratio (4.29 vs 1.87, P = 0.018) and TNF-α/IL-12p70 ratio (7.49 vs 5.21, P = 0.018) with respect to renal involvement.

Conclusion: Increased levels of a number of immunomodulatory cytokines relative to IL-12p70 in this Caucasian SLE patient population are seen in patients with renal involvement and are associated with increased accrual of damage at the 5-year follow-up.