One of the most important pro-inflammatory cytokines in the pathophysiology of rheumatoid arthritis (RA) is interleukin 1 (IL-1). The purpose of this study is to evaluate the association between IL-1B (-511), IL-1 (+3953), IL-1 RN variable number of tandem repeat (VNTR) polymorphisms and the occurrence in Algerian patients with rheumatoid arthritis. We also analyze their correlations with clinical and biological phenotypes.
One hundred and forty-seven patients with RA (119 women, 28 men) and 127 controls (70 women, 57 men) were included in the study. The analysis of two polymorphisms of IL-1B-511 and IL-1B+3953 was done by PCR-RFLP. Analysis of IL1-RN VNTR polymorphism was performed by PCR.
No significant difference in genotype, allelic and haplotype distribution at the three polymorphisms was observed between RA patients and controls. However, the genotype (T/T) polymorphism of IL-1B-511 is more frequent in the group of patients with positive ACPA compared with negative ACPA group (Pc=0.01, OR=4.65). Moreover, we noted that the haplotype (IL-1RN* 1/IL-1B-511T/IL-1B+3953C) was more frequent (Pc=0.03, OR=2.05) in the positive ACPA group.
The association between the allele 1 of IL-1 RN VNTR, T allele of IL1B-511 and C allele of IL1-B +3953 polymorphisms seems to predispose to the synthesis of ACPA and therefore to the occurrence of ACPA positive RA. Further studies with a larger number of patients are needed to define the real role of IL-1 in the susceptibility to or severity of RA.