A pathway-based association study reveals variants from Wnt signalling genes contributing to asthma susceptibility

BACKGROUND

Genetic susceptibility to asthma is currently linked to a handful of genes which have a limited ability to predict the overall disease risk, suggesting the existence of many other genes involved in disease development. Accumulated evidence from association studies in genes related by biological pathways could reveal novel asthma genes.

OBJECTIVE

To reveal novel asthma susceptibility genes by means of a pathway-based association study.

METHODS

Based on summary data from a previous a genomewide association study (GWAS) of asthma, we first identified significant biological pathways using a gene-set enrichment analysis. We then mapped all tested single nucleotide polymorphisms (SNPs) on the genes contributing to significant pathways and prioritized those with a disproportionate number of nominal significant associations for further studies. For those prioritized genes, association studies were performed for selected SNPs in independent case-control samples (n = 1765) using logistic regression models, and results were meta-analysed with those from the GWAS.

RESULTS

Two biological processes were significantly enriched: the cytokine-cytokine receptor interaction (P = 0.002) and the Wnt signalling (P = 0.012). From the 417 genes interacting in these two pathways, 10 showed an excess of nominal associations, including a known asthma susceptibility locus (encoding SMAD family member 3) and other novel candidate genes. From the latter, association studies of 14 selected SNPs evidenced replication in a locus near the frizzled class receptor 6 (FZD6) gene (P = 9.90 × 10^-4 ), which had a consistent direction of effects with the GWAS findings (meta-analysed odds ratio = 1.49; P = 5.87 × 10^-6 ) and was in high linkage disequilibrium with expression quantitative trait loci in lung tissues.

CONCLUSIONS AND CLINICAL RELEVANCE

This study revealed the importance of two biological pathways in asthma pathogenesis and identified a novel susceptibility locus near Wnt signalling genes.

Anti-TNF-α therapy reduces retinol-binding protein 4 serum levels in non-diabetic patients with psoriasis: a 6-month prospective study

BACKGROUND

Retinol-binding protein-4 (RBP4), an adipokine considered as an emerging cardiometabolic risk factor, is increased in patients with moderate-to-severe psoriasis.

OBJECTIVE

In this study, we aimed to establish the effect of anti-TNF-α therapy on RBP4 levels in patients with moderate-to-severe psoriasis. We also assessed if RBP4 levels correlate with metabolic syndrome features and disease severity in these patients.

METHODS

Prospective study on a series of consecutive non-diabetic patients with moderate-to-severe psoriasis who completed 6 months of therapy with adalimumab. Patients with kidney disease, hypertension or body mass index ≥ 35 kg/m(2) were excluded. Metabolic and clinical evaluation was performed at the onset of treatment (time 0) and at month 6.

RESULTS

Twenty-nine patients were assessed. Statistically significant reduction (P = 0.0001) of RBP4 levels was observed after 6 months of therapy (RBP4 at time 0: 55.7 ± 21.4 μg/mL, vs. 35.6 ± 29.9 μg/mL at month 6). No significant correlation between basal RBP4 levels and metabolic syndrome features or disease severity was found. Nevertheless, although RBP4 levels did not correlate with insulin resistance, a negative and significant correlation between RBP4 levels obtained after 6 months of adalimumab therapy and other metabolic syndrome features such as abdominal perimeter and body mass index were observed. At that time, a negative and significant correlation between RBP4 levels and disease activity scores and ultrasensitive CRP levels was also disclosed.

CONCLUSION

Our results support an influence of the anti-TNF-α blockade on RBP4 serum levels. This finding is of potential relevance due to increased risk of cardiovascular disease in patients with psoriasis.

The 11q23.3 genomic region-rs964184-is associated with cardiovascular disease in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory disease associated with high risk of cardiovascular (CV) events. Recently, the rs964184 polymorphism has been associated with coronary artery disease in nonrheumatic Caucasian individuals. 2160 Spanish RA patients were genotyped for the rs964184 polymorphism. Sex, age at diagnosis and traditional CV risk factors (diabetes mellitus, dyslipidemia and smoking habit) were associated with increased risk of CV events. Interestingly, RA patients carrying the rs964184 GG genotype had significantly higher risk of CV events than those with CC genotype [hazard ratio (HR) = 2.91, 95% confidence interval (CI): 1.36-6.26, P = 0.006] after adjusting the results for sex, age at diagnosis and traditional CV risk factors. Our results indicate that rs964184 polymorphism is associated with CV disease in RA.