Susceptibility of Interleukin 1-beta (IL-1β) gene polymorphisms associated with Rheumatoid arthritis

Abstract

Rheumatoid arthritis is a progressive and chronic autoimmune disease which affects all racial and ethnic groups. The incidence or prevalence of rheumatoid arthritis varies across different geographic regions of the world and across different time periods. Globally it affects almost 0.5- 1.0 per cent of the general population. In Pakistan it affects 0.3-0.9 per cent of the population. The disease can cause inflammation of one or more joints of the body. Several cytokines regulate key inflammatory pathways that are involved in the progression of disease. Interleukin-1 beta (IL-1β) is a crucial cytokine for the development of rheumatoid arthritis, which is secreted by synovial macrophages and is involved in the upregulation of inflammatory cells in the synovium, differentiation of osteoclast progenitors into preosteoclasts and regulation of the levels of other immunoregulatory molecule. Rheumatoid arthritis may be caused by genetic variations found in the IL-1β gene's regulatory regions. The important role being played by IL-1β signifies the candidacy of this gene for disease pathogenesis. In this study, the association of four SNPs rs2853550 (SNP-1, intergenic variant) and rs1143643 (SNP-2, intronic variant) of IL-1β gene and rs16944 (SNP-3, intergenic variant), rs3136558 (SNP-4 intronic variant) was studied in 100 rheumatoid arthritis patients from Pakistani population. These polymorphisms were examined using allele-specific PCR, and the data were statistically examined for any evidence of a connection between these polymorphisms and Rheumatoid arthritis. According to the findings of our study, SNP-1 and SNP-2 of the IL-1β gene were strongly related to Rheumatoid arthritis in our patients, however SNP-3 and SNP-4 were not. Other single nucleotide polymorphisms (SNPs) located in the regulatory and untranslated regions of the IL-1β gene may have significant association towards Rheumatoid arthritis, for which large scale data is required. However, more molecules implicated in the inflammatory pathway of rheumatoid arthritis need to be investigated for the genetic association with disease pathogenesis.