Influence of MIF, CD40, and CD226 polymorphisms on risk of rheumatoid arthritis

Macrophage migration inhibitory factor (MIF) is a key pro-inflammatory mediator. It plays an important role part in the pathogenesis of several inflammatory and immune diseases. A functional single nucleotide polymorphism (SNP) of MIF -173 G/C is known to influence MIF promoter activity in T lymphoblast cell lines and is associated with a higher serum MIF level. The CD40 is also crucial for some relevant functions of the immune system and may be related to rheumatoid arthritis (RA). And CD226 is an important cell-surface receptor molecule involved in the adhesion and activation of T-cell. We hypothesized that these polymorphisms may contribute to RA susceptibility. We studied MIF -173 G/C, CD40, and CD226 gene polymorphisms in 214 patients with RA and 478 controls in a Chinese population. Genotyping was done by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). When the MIF -173 GG homozygote genotype was used as the reference group, the CC genotype was associated with a significantly increased risk for RA. In the recessive model, when the MIF -173 GG/GC genotypes were used as the reference group, the CC homozygote genotype was associated with a significant 1.56-fold increased susceptibility to RA. None of the CD40 rs1883832 C/T and CD226 rs763361 C/T polymorphisms achieved a significant difference in genotype distributions between cases and controls. In the stratification analyzes, a significantly increased risk for RA associated with the MIF -173 CC genotype was evident among CRP-negative patients compared with the MIF -173 GG/GC genotype. For the CD40 rs1883832 C/T variant, the risk effects of CD40 rs1883832 TT versus CD40 rs1883832 CC/CT were significant in men. These findings suggested that the functional SNP MIF -173 G/C variant allele was associated with the development of RA. However, CD40 and CD226 gene polymorphisms may not be associated with RA susceptibility. Due to the limitation of sample size, this study should be considered preliminary.