Transcriptome analysis of the perivascular adipose tissue in peripheral artery disease patients

Perivascular adipose tissue (PVAT) is thought to play a role in vascular homeostasis and in the pathogenesis of diseases of large vessels. We tested the hypothesis that locally restricted transcriptional profiles characterize the PVAT localized at the site of the obstruction of the abdominal aorta in peripheral artery disease (PAD) patients. By a genome-wide approach and a paired-samples design, we investigated the PVAT transcriptome of 11 PAD patients with occlusive and with stenotic abdominal aortic lesions. We performed a data adjustment step using the DaMiRseq R/Bioconductor package, to remove the effect of confounders as produced by high-throughput gene expression techniques. We compared PVAT of the distal versus the proximal aorta of each patient to limit the effect of inter-individual variability, using the limma R/Bioconductor package. We did not find consistent differences in PVAT gene expression clearly distinguishing the two PVAT of the same patient. However, we found significant differences by comparing patients with total occlusive versus those with stenotic abdominal aortic lesions. We dissected putative mechanisms associated with PVAT involvement in PAD patients with total occlusive and with stenotic abdominal aorta lesions through a functional enrichment network analysis: cholesterol, sterol and alcohol biosynthetic process were enriched in patients with total occlusive lesions, whereas pathways recalling the structure maintenance and remodeling of the vessels were associated with patients with stenotic lesions. Our results would suggest that the PVAT transcriptome at the distal aorta site is associated with the degree of the atherosclerotic burden in PAD patients and that this effect can probably account for a diffuse (systemic) process affecting homogenously the PVATs spanning along the distal aorta rather than a singular specific trait. A paired-sample study design was used to reduce the problem of inter-individual variations. Eleven patients with PAD were consecutively enrolled. Diverse adipose tissue (AT) depots were safely obtained sequentially, in the following order: subcutaneous abdominal fat, omental-visceral fat, periaortic fat obtained from the aortic neck proximal to the lesion, and periaortic fat surrounding the lesion. RNA was extracted from 50-100 mg of frozen AT samples. RNA samples of poor quality and yield were discarded.