Interleukin-18 promoter polymorphisms in patients with systemic lupus erythematosus.

Objectives: The role of various polymorphisms located in the IL-18 promoter has not yet been defined with regards to patient susceptibility to SLE, and occurrence of clinical manifestations of the disease remains inconsistent.

Methods: Using PCR-RFLP and DNA sequencing analysis we studied the frequency of -137 G/C (rs187238), -607 C/A (rs1946518) and -1297C/T (rs360719) polymorphisms in IL-18 promoter in patients with SLE from a sample of the Polish population.

Results: We observed that patients with SLE bearing the IL-18 -1297CC genotype exhibited a 2.536-fold increased risk of SLE incidence (95% CI=1.333-4.826, p=0.0035). We also found a significantly higher frequency of the IL-18 -1297C allele in patients than in controls, with odds ratio (OR) for the IL-18 -1297C allele in patients with SLE being 1.558 (95% CI=1.189-2.041, p=0.0013). Moreover, there was an association between the IL-18 -1297CC genotype and renal manifestations of SLE, OR=3.792 (1.446-9.947, p=0.0051). However, we did not find any contribution of the IL-18 -607 C/A and -137 G/C polymorphisms to SLE incidence or occurrence of the studied SLE manifestations.

Conclusions: Our findings confirmed that the IL-18 -1297C gene variant may contribute to the risk of SLE incidence. Moreover, IL-18 -1297CC might be associated with renal manifestations of SLE.