Genetic determinants of risk in pulmonary arterial hypertension: international genome-wide association studies and meta-analysis

Background Rare genetic variants cause pulmonary arterial hypertension, but the contribution of common genetic variation to disease risk and natural history is poorly characterised. We tested for genome-wide association for pulmonary arterial hypertension in large international cohorts and assessed the contribution of associated regions to outcomes. Methods We did two separate genome-wide association studies (GWAS) and a meta-analysis of pulmonary arterial hypertension. These GWAS used data from four international case-control studies across 11744 individuals with European ancestry (including 2085 patients). One GWAS used genotypes from 5895 whole-genome sequences and the other GWAS used genotyping array data from an additional 5849 individuals. Cross-validation of loci reaching genome-wide significance was sought by meta-analysis. Conditional analysis corrected for the most significant variants at each locus was used to resolve signals for multiple associations. We functionally annotated associated variants and tested associations with duration of survival. All-cause mortality was the primary endpoint in survival analyses. Findings A locus near SOX17 (rs10103692, odds ratio 1·80 [95% CI 1·55–2·08], p=5·13×10– ¹⁵) and a second locus in HLA-DPA1 and HLA-DPB1 (collectively referred to as HLA-DPA1/DPB1 here; rs2856830, 1·56 [1·42–1·71], p=7·65×10– ²⁰) within the class II MHC region were associated with pulmonary arterial hypertension. The SOX17 locus had two independent signals associated with pulmonary arterial hypertension (rs13266183, 1·36 [1·25–1·48], p=1·69×10– ¹²; and rs10103692). Functional and epigenomic data indicate that the risk variants near SOX17 alter gene regulation via an enhancer active in endothelial cells. Pulmonary arterial hypertension risk variants determined haplotype-specific enhancer activity, and CRISPR-mediated inhibition of the enhancer reduced SOX17 expression. The HLA-DPA1/DPB1 rs2856830 genotype was strongly associated with survival. Median survival from diagnosis in patients with pulmonary arterial hypertension with the C/C homozygous genotype was double (13·50 years [95% CI 12·07 to >13·50]) that of those with the T/T genotype (6·97 years [6·02–8·05]), despite similar baseline disease severity. Interpretation This is the first study to report that common genetic variation at loci in an enhancer near SOX17 and in HLA-DPA1/DPB1 is associated with pulmonary arterial hypertension. Impairment of SOX17 function might be more common in pulmonary arterial hypertension than suggested by rare mutations in SOX17. Further studies are needed to confirm the association between HLA typing or rs2856830 genotyping and survival, and to determine whether HLA typing or rs2856830 genotyping improves risk stratification in clinical practice or trials. Funding UK NIHR, BHF, UK MRC, Dinosaur Trust, NIH/NHLBI, ERS, EMBO, Wellcome Trust, EU, AHA, ACClinPharm, Netherlands CVRI, Dutch Heart Foundation, Dutch Federation of UMC, Netherlands OHRD and RNAS, German DFG, German BMBF, APH Paris, INSERM, Université Paris-Sud, and French ANR

Changes in the stem-loop at the 3' terminus of histone mRNA affects its nucleocytoplasmic transport and cytoplasmic regulation.

The stem-loop structure at the 3' end of replication-dependent histone mRNA is required for efficient pre-mRNA processing, localization of histone mRNA to the polyribosomes, and regulation of histone mRNA degradation. A protein, the stem-loop binding protein (SLBP), binds the 3' end of histone mRNA and is thought to mediate some or all of these processes. A mutant histone mRNA with two nucleotide changes in the loop was constructed and found to be transported inefficiently to the cytoplasm. The mutant histone mRNA, unlike the wild-type histone mRNA, was not rapidly degraded when DNA synthesis is inhibited, and was not stabilized upon inhibition of protein synthesis. The stem-loop binding protein (SLBP) has between a 20-50 fold greater affinity for the wild type histone stem-loop structure than for the mutant stem-loop structure, suggesting that the alteration in the efficiency of transport and the normal degradation pathway in histone mRNA may be due to the reduced affinity of the mutant stem-loop for the SLBP

Increasing the distance between the snRNA promoter and the 3' box decreases the efficiency of snRNA 3'-end formation.

Chimeric genes which contained the mouse U1b snRNA promoter, portions of the histone H2a or globin coding regions and the U1b 3'-end followed by a histone 3'-end were constructed. The distance between the U1 promoter and the U1 3' box was varied between 146 and 670 nt. The chimeric genes were introduced into CHO cells by stable transfection or into Xenopus oocytes by microinjection. The efficiency of utilization of the U1 3' box, as measured by the relative amounts of transcripts that ended at the U1 3' box and the histone 3'-end, was dependent on the distance between the promoter and 3'-end box. U1 3'-ends were formed with >90% efficiency on transcripts shorter than 200 nt, with 50-70% efficiency on transcripts of 280-400 nt and with only 10-20% efficiency on transcripts >500 nt. Essentially identical results were obtained after stable transfection of CHO cells or after injecting the genes into Xenopus oocytes. The distance between the U1 promoter and the U1 3' box must be <280 nt for efficient transcription termination at the U1 3' box, regardless of the sequence transcribed

Safety and Efficacy of Combined Resveratrol and Sirolimus in Lymphangioleiomyomatosis

BACKGROUND: A critical need exists to develop remission-inducing therapies for lymphangioleiomyomatosis. RESEARCH QUESTION: Is the addition of resveratrol safe and more efficacious than sirolimus alone in patients with lymphangioleiomyomatosis? STUDY DESIGN AND METHODS: We conducted a phase 2, dose-escalating, open-label trial of resveratrol in patients with lymphangioleiomyomatosis receiving a stable regimen of sirolimus. Resveratrol was started at 250 mg/d and escalated every 8 weeks to maximum dose of 1,000 mg/d over 24 weeks. The primary outcome was ≥ 42% decline in serum vascular endothelial growth factor D (VEGF-D) levels on combined therapy compared with baseline VEGF-D levels on sirolimus. Secondary objectives included an assessment of the safety profile and the effect on lung function and health-related quality of life (HRQOL). Longitudinal change in outcome measures was assessed using linear mixed models. Adverse effects were tabulated using the National Cancer Institute\u27s Common Terminology Criteria for Adverse Events version 4. RESULTS: Twenty-five patients with lymphangioleiomyomatosis with a median age of 51 years were enrolled. Pulmonary function parameters at study inclusion were: FEV: median absolute, 1.72 L; 64% predicted; FVC: median absolute, 2.99 L; 96% predicted; and diffusing capacity of the lungs for carbon monoxide: median absolute, 14.68 mL/mm Hg/min; 37% predicted. The median serum VEGF-D value at baseline was 617 pg/mL. Patients entered the study with a median sirolimus dose of 2 mg/d with median trough level of 6.3 ng/mL. Despite some GI side effects, the addition of resveratrol was well tolerated. Although the primary outcome was not met, a statistically significant reduction in serum VEGF-D levels and improvement in HRQOL during the study was found. INTERPRETATION: The addition of resveratrol was safe and well tolerated in patients with lymphangioleiomyomatosis taking sirolimus and was associated with modest improvement in HRQOL. Larger controlled trials of this combination might be warranted to assess definitively the usefulness of resveratrol as an additive therapy in lymphangioleiomyomatosis. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT03253913; URL: www. CLINICALTRIALS: gov