Relationship of macrophage migration inhibitory factor level and -173 G/C single nucleotide polymorphism with rheumatoid arthritis

Abstract

Background: Rheumatoid arthritis (RA) is autoimmune illness due to different reasons, one of these reasons is high level or Single Nucleotide Polymorphism (SNP) in cytokines as Macrophage Migration Inhibitory Factor (MIF). There is no study detect or relate MIF level and/or MIF-173 G/C SNP with RA in Iraq population. Aim: This study aimed to investigate the present and/or the contribution of MIF level and/or MIF-173 G/C SNP to RA development in Iraq population. Methods: This study covered 44 cases of rheumatoid arthritis patients and 44 apparently healthy persons as a control. Blood was collected and transferred into 2 tubes: gel tube for obtain serum to detect Rheumatoid Factor (RF) and C-Reactive Protein (CRP) seropositivity by agglutination and measure MIF level by ELISA; and EDTA tube used for extraction and amplification of DNA for study of MIF -173 G/C SNP by Amplification Refractory Mutation System- Polymerase Chain Reaction (ARMS-PCR) and Sanger DNA sequencing method. Both samples were stored in -20°C for later use.Results: Significantly (P=0.000) both RF and CRP were more positive (47.73% and 40.9%) in RA than healthy control (4.55% and 6.82 %), respectively. The serum MIF (ng/ml) level in RA (3.699±0.602), was significantly (P=0.040) higher than in controls (2.311±0.269). ARMS-PCR, showed that MIF has insignificant (P=0.456) difference in the distribution of three genotypes at -173 locus of promoter with frequencies in RA: GG (34.09%) and GC (65.91%); in controls: GG (40.91%), GC (56.82%) and CC (2.27%). Moreover, MIF-173 GC genotype in RA was associated significantly (P=0.040, P=0.044, P=0.042) with high MIF level, positive RF and positive CRP (4.488±0.824 ng/ml, 58.62% and 51.72%) than in control (2.534±0.398 ng/ml, 26.7% and 20%), respectively. Conclusion: RA specially with MIF-173 GC genotype associated significantly with elevated MIF level, positive RF and positive CRP.