Apolipoprotein H Promoter Polymorphisms in Relation to Lupus and Lupus-related Phenotypes

Abstract

Objective.Sequence variation in gene promoters is often associated with disease risk. We tested the hypothesis that common promoter variation in the APOH gene (encoding for ß2-glycoprotein I) is associated with systemic lupus erythematosus (SLE) risk and SLE-related clinical phenotypes in a Caucasian cohort.Methods.We used a case-control design and genotyped 345 women with SLE and 454 healthy control women for 8APOHpromoter single-nucleotide polymorphisms (SNP; –1284C>G, –1219G>A, –1190G>C, –759A>G, –700C>A, –643T>C, –38G>A, and –32C>A).Association analyses were performed on single SNP and haplotypes. Haplotype analyses were performed using EH (Estimate Haplotype–frequencies) and Haploview programs.In vitroreporter gene assay was performed in COS-1 cells. Electrophoretic mobility shift assay (EMSA) was performed using HepG2 nuclear cells.Results.Overall haplotype distribution of theAPOHpromoter SNP was significantly different between cases and controls (p = 0.009). The –643C allele was found to be protective against carotid plaque formation (adjusted OR 0.37, p = 0.013) among patients with SLE. The –643C allele was associated with a ~2-fold decrease in promoter activity as compared to wild-type –643T allele (mean ± standard deviation: 3.94 ± 0.05 vs 6.99 ± 0.68, p = 0.016). EMSA showed that the –643T>C SNP harbors a binding site for a nuclear factor. The –1219G>A SNP showed a significant association with the risk of lupus nephritis (age-adjusted OR 0.36, p = 0.016).Conclusion.Our data indicate thatAPOHpromoter variants may be involved in the etiology of SLE, especially the risk for autoimmune-mediated cardiovascular disease.