Cardiovasc Res. 2022 Jan 10. pii: cvac007. [Epub ahead of print]
AIMS: Vascular stiffness increases with age and independently predicts cardiovascular disease risk. Epigenetic changes, including histone modifications, accumulate with age but the global pattern has not been elucidated nor are the regulators known. Smooth muscle cell-mineralocorticoid receptor (SMC-MR) contributes to vascular stiffness in aging mice. Thus, we investigated the regulatory role of SMC-MR in vascular epigenetics and stiffness.METHODS AND RESULTS: Mass spectrometry-based proteomic profiling of all histone modifications completely distinguished 3 from 12-month-old mouse aortas. Histone-H3 lysine-27(H3K27) methylation(me) significantly decreased in aging vessels and this was attenuated in SMC-MR-KO littermates. Immunoblotting revealed less H3K27-specific methyltransferase EZH2 with age in MR-intact but not SMC-MR-KO vessels. These aging changes were examined in primary human aortic (HA)SMC from adult versus aged donors. MR, H3K27 acetylation(ac), and stiffness gene (CTGF, Integrin-α5) expression significantly increased, while H3K27me and EZH2 decreased, with age. MR inhibition reversed these aging changes in HASMC and the decline in stiffness genes was prevented by EZH2 blockade. Atomic force microscopy revealed that MR antagonism decreased intrinsic stiffness and the probability of fibronectin adhesion of aged HASMC. Conversely, aging induction in young HASMC with H2O2; increased MR, decreased EZH2, enriched H3K27ac and MR at stiffness gene promoters by ChIP, and increased stiffness gene expression. In 12-month-old mice, MR antagonism increased aortic EZH2 and H3K27 methylation, increased EZH2 recruitment and decreased H3K27ac at stiffness genes promoters, and prevented aging-induced vascular stiffness and fibrosis. Finally, in human aortic tissue, age positively correlated with MR and stiffness gene expression and negatively correlated with H3K27me3 while MR and EZH2 are negatively correlated.
CONCLUSION: These data support a novel vascular aging model with rising MR in human SMC suppressing EZH2 expression thereby decreasing H3K27me, promoting MR recruitment and H3K27ac at stiffness gene promoters to induce vascular stiffness and suggests new targets for ameliorating aging-associated vascular disease.
TRANSLATIONAL PERSPECTIVE: These findings provide a new epigenetic mechanism whereby rising MR in aging human SMC promotes vascular stiffness. Vascular stiffness contributes to common disorders of aging including hypertension, heart and kidney failure, and stroke, yet no therapies successfully target vascular stiffness. Drugs that inhibit MR are already approved and used in the elderly. In addition, drugs targeting histone-modifying enzymes, including EZH2, are being developed to treat cancer. Thus, these results provide preclinical support for drugs that could be immediately tested to treat aging-associated vascular stiffness and raise the potential for some cancer therapies to promote vascular stiffness.