Abstract Body: Background. Calcific aortic valve stenosis (AVS) is the most prevalent valvular heart disease in the Western world, for which no disease-modifying therapy yet exists. High shear stress (HSS) generated by progressive valvular obstruction is a known initiator of endothelial injury and immune-mediated inflammation, but the mechanistic contribution of circulating T cells to AVS pathogenesis remains undefined. We hypothesized that chronic HSS induces an epigenomic reprogramming of peripheral T cells, contributing to immunomodulatory dysregulation that drives disease progression.
Methods. We enrolled a prospective cohort of 35 patients with severe, symptomatic AVS scheduled for transcatheter aortic valve replacement (TAVR) and 35 age- and sex-matched controls with intact valve hemodynamics. Genome-wide CpG methylation profiling of peripheral T cells was performed using the Illumina Infinium MethylationEPIC BeadChip array alongside RNA-sequencing (n=54) as a functional readout.
Results. Unsupervised clustering of the most-variable CpG loci separated AVS from control T cells (PC1; 15.8% variance; P = 3.9×10^-6), and MOFA integration identified the latent factor that independently predicts AVS (P = 2.4x10^-4); this factor robustly enriched chemokine receptor (P = 1.1×10^-6) and TNF ligand-receptor (P = 6.9×10^-5) interactions. Using a novel microfluidics-based in vitro system, we established a mechanistic link between hemodynamic stress and T cell activation via NFAT siganling. To predict AVS severity using only the T cell epigenome, we developed a methylation risk score (MRS) derived from 30 elastic-net–selected CpGs, which uncovered a diagnostic-level precision (AUC=0.99; DeLong P = 0.047); MRS quartile stratification revealed a monotonic increase in AVS discrimination (P = 3.3×10^-5). Multivariable regression further confirmed MRS as an independent predictor of aortic valve area (β=−0.112±0.08 cm²/SD; P = 0.008) even after adjustment for age and sex.
Conclusions. Severe AVS is accompanied by widespread, promoter-enriched epigenomic remodeling of circulating T cells that converge onto shear stress-dependent CpG methylation programs. A 30-CpG methylation risk score offers the first liquid biopsy-based diagnostic approach to uncover both the presence and severity of AVS. Together, we describe the first evidence that peripheral immunoepigenetic reprogramming is both a mechanistic mediator of immune dysregulation and a clinically informative biomarker in human AVS.