T cell-derived miR-214 mediates perivascular fibrosis in hypertension

Despite increasing understanding of the prognostic importance of vascular stiffening linked to perivascular fibrosis in hypertension, the molecular and cellular regulation of this process is poorly understood. We aimed to study the functional role of microRNA-214 (miR-214) in the induction of perivascular fibrosis and endothelial dysfunction driving vascular stiffening. Out of 381 miRs screened in the perivascular tissues (PVAT) in response to angiotensin II (Ang II)-mediated hypertension, miR-214 showed the highest induction (8-fold, p<0.01). MiR-214 induction was pronounced in perivascular and circulating T cells, but not in PVAT adipocytes. Global deletion of miR-214-/- prevented Ang II-induced periaortic fibrosis Col1a1, Col3a1, Col5a1 and Tgfb1 expression, hydroxyproline accumulation and vascular stiffening, without difference in blood pressure. Mechanistic studies revealed that miR-214-/- mice were protected against endothelial dysfunction, oxidative stress and increased Nox2, all of which were induced by Ang II in WT mice. Ang II-induced recruitment of T cells into PVAT was abolished in miR-214-/- mice. Adoptive transfer of miR-214-/- T cells into RAG1-/- mice resulted in reduced perivascular fibrosis compared to the effect of WT T cells. Ang II induced hypertension caused significant change in the expression of 1380 T cell genes in WT, but only 51 in miR-214-/-. T cell activation, proliferation and chemotaxis pathways were differentially affected. miR-214-/- prevented Ang II-induction of pro-fibrotic T cell cytokines (IL-17, TNF, IL-9 and IFN) and chemokine receptors (CCR1, CCR2, CCR4, CCR5, CCR6 and CXCR3). This manifested in reduced in vitro and in vivo T cell chemotaxis resulting in attenuation of profibrotic perivascular inflammation. Translationally, we show that miR-214 is increased in plasma of hypertensive patients and is directly correlated to pulse wave velocity as a measure of vascular stiffness. RNA-Seq analysis of isolated splenic T cells from sham and angiotensin II infused WT and miR-214 KO mice (n=3 in each group)