Vaspin in atherosclerotic disease and cardiovascular risk in axial spondyloarthritis: a genetic and serological study.

BACKGROUND: Vaspin is a novel anti-inflammatory adipokine associated with cardiovascular (CV) disease and inflammation in chronic inflammatory conditions different from axial spondyloarthritis (axSpA). Given the high incidence of CV disease (mainly due to accelerated atherosclerosis) exhibited by axSpA patients, we wondered if vaspin could also be a key molecule in this process. However, data on the role of vaspin regarding atherosclerotic disease in the context of axSpA is scarce. For this reason, we aimed to evaluate the implication of vaspin, at the genetic and serological level, in subclinical atherosclerosis and CV risk in axSpA. METHODS: This study included 510 patients diagnosed with axSpA. Carotid ultrasound (US) was performed to evaluate the presence of subclinical atherosclerosis. Three vaspin gene variants (rs2236242, rs7159023, and rs35262691) were genotyped by TaqMan probes. Serum vaspin levels were assessed by enzyme-linked immunosorbent assay. Statistical analysis was performed using STATA® v.11.1. RESULTS: Serum vaspin levels were significantly higher in female patients than in males and also in obese patients when compared to those with normal weight (p < 0.05). At the genetic level, we disclosed that the minor allele of rs2236242 (A) was associated with lower serum vaspin levels in axSpA, while the rs7159023 minor allele (A) was linked to higher serum levels (p < 0.05). When the three polymorphisms assessed were combined conforming haplotypes, we disclosed that the TGC haplotype related to high serum levels of vaspin (p = 0.01). However, no statistically significant association was observed between vaspin and markers of subclinical atherosclerosis, both at the genetic and serological level. CONCLUSIONS: Our results revealed that vaspin is linked to CV risk factors that may influence on the atherosclerotic process in axSpA. Additionally, we disclosed that serum vaspin concentration is genetically modulated in a large cohort of patients with axSpA.

PXK locus in systemic lupus erythematosus: fine mapping and functional analysis reveals novel susceptibility gene ABHD6.

OBJECTIVES: To perform fine mapping of the PXK locus associated with systemic lupus erythematosus (SLE) and study functional effects that lead to susceptibility to the disease. METHODS: Linkage disequilibrium (LD) mapping was conducted by using 1251 SNPs (single nucleotide polymorphism) covering a 862 kb genomic region on 3p14.3 comprising the PXK locus in 1467 SLE patients and 2377 controls of European origin. Tag SNPs and genotypes imputed with IMPUTE2 were tested for association by using SNPTEST and PLINK. The expression QTLs data included three independent datasets for lymphoblastoid cells of European donors: HapMap3, MuTHER and the cross-platform eQTL catalogue. Correlation analysis of eQTLs was performed using Vassarstats. Alternative splicing for the PXK gene was analysed on mRNA from PBMCs. RESULTS: Fine mapping revealed long-range LD (>200 kb) extended over the ABHD6, RPP14, PXK, and PDHB genes on 3p14.3. The highly correlated variants tagged an SLE-associated haplotype that was less frequent in the patients compared with the controls (OR=0.89, p=0.00684). A robust correlation between the association with SLE and enhanced expression of ABHD6 gene was revealed, while neither expression, nor splicing alterations associated with SLE susceptibility were detected for PXK. The SNP allele frequencies as well as eQTL pattern analysed in the CEU and CHB HapMap3 populations indicate that the SLE association and the effect on ABHD6 expression are specific to Europeans. CONCLUSIONS: These results confirm the genetic association of the locus 3p14.3 with SLE in Europeans and point to the ABHD6 and not PXK, as the major susceptibility gene in the region. We suggest a pathogenic mechanism mediated by the upregulation of ABHD6 in individuals carrying the SLE-risk variants.