Integrative omics to reveal endothelial mesenchymal transition as critical biological function associated with poor reverse cardiac remodelling in aortic stenosis patients

Aortic valve stenosis (AS), a major cause of heart failure, is driven by chronic pressure overload that induces left ventricular (LV) hypertrophy and fibrosis. Surgical or transcatheter aortic valve replacement relieves the hemodynamic stress and initiates a reverse remodelling, a process characterized by gradual structural and functional recovery of the myocardium. Although regression of hypertrophy and fibrosis begins shortly after surgery, complete normalization of LV mass is not achieved in a substantial proportion of patients. Understanding the molecular mechanisms underlying poor reverse remodelling is therefore essential to identify novel therapeutic targets for mitigating adverse cardiac remodelling and promoting myocardial recovery.

Co-profiling miRNA/mRNA in preoperative LV biopsies from AS patients to identify potential targets determinant of favourable reverse remodelling one year after valve replacement surgery.

The study was performed in AS (n=24) and control patients (n=12) (age and sex matched) followed up for one year after surgery. RNA-seq and miRNA-seq were performed on LV biopsies obtained during surgery. AS patients were stratified according to the quality of the reverse remodelling at one year in good (LV mass index ≤51 g/m2.7, n=12) or poor (LV mass index >51 g/m2.7, n=12) performers. Potential interactions between differentially expressed (DE) miRNAs and DEmRNAs were explored using the mirTarRnaSeq R package, based on expression correlations and cross-referenced with predicted interactions from the miRanda database. Gene set enrichment analysis performed on DE mRNAs targeted by DE miRNAs revealed enrichment in pathways associated with epithelial-mesenchymal transition (EMT) (NES=1.97). DEgenes related with EMT (RGS4 and POSTN) and their validated miRNA, miR-26a, were also found to be inversely deregulated in LV from AS patients with poor reverse remodelling (validation by qPCR; n=98). Overexpression of POSTN (2.96±0.33) and RGS4 (1.41±0.082 in males) along with an inverse correlation with miR-26a values (vs POSTN r=-0.46*; vs RGS4 r=-0.44* in males), were also observed in the LV of our animal model of transverse aortic constriction (TAC) after 4 weeks. In addition, reverse remodelling in mice LV after pressure overload release (de-TAC) was accompanied by a decrease in the expression of POSTN and RGS4. Interestingly, overexpression of miR-26a inhibited migration and EndTM in our cytokine-based EndTM in vitro model, accompanied by a decrease of RGS4 expression.

Performing integrative miRNA/mRNA co-profiling in LV from AS patients, were able to (1) establish EMT as a critical function associated with poor reverse remodelling in AS patients; (2) identify downregulation of RGS4 and POSTN, and upregulation of miR-26 as a shared process in the LV of our TAC and de-TAC animal model; (3) establish the anti-migration and anti-EndMT properties of miR-26 in our in vitro model.