MiR487b is edited in the seed sequence in mice and humans, resulting in a novel, proangiogenic microRNA with a unique targetome. The rate of miR487b editing, as well as 2'-O-ribose-methylation, is increased in murine muscle tissue during postischemic neovascularization. Our findings suggest miR487b editing plays an intricate role in postischemic neovascularization.

Objective: T-cells are central to the immune response responsible for native atherosclerosis. The objective of this study is to investigate T-cell contribution to post-interventional accelerated atherosclerosis development, as well as the role of the CD28-CD80/86 co-stimulatory and Cytotoxic T-Lymphocyte Antigen (CTLA)-4 co-inhibitory pathways controlling T-cell activation status in this process. Methods and results: The role of T-cells and the CD28-CD80/86 co-stimulatory and CTLA-4 co-inhibitory pathways were investigated in a femoral artery cuff mouse model for post-interventional remodeling, with notable intravascular CTLA-4+ T-cell infiltration. Reduced intimal lesions developed in CD4 −/− and CD80 −/− CD86 −/− mice compared to normal C57Bl/6J controls. Systemic abatacept-treatment, a soluble CTLA-4Ig fusion protein that prevents CD28-CD80/86 co-stimulatory T-cell activation, prevented intimal thickening by 58.5% (p = 0.029). Next, hypercholesterolemic ApoE3*Leiden mice received abatacept-treatment which reduced accelerated atherosclerosis development by 78.1% (p = 0.040) and prevented CD4 T-cell activation, indicated by reduced splenic fractions of activated KLRG1 +, PD1 +, CD69+ and CTLA-4+ T-cells. This correlated with reduced plasma interferon-γ and elevated interleukin-10 levels. The role of CTLA-4 was confirmed using CTLA-4 blocking antibodies, which strongly increased vascular lesion size by 66.7% (p=0.008), compared to isotype-treated controls. Conclusions: T-cell CD28-CD80/86 co-stimulation is vital for post-interventional accelerated atherosclerosis development and is regulated by CTLA-4 co-inhibition, indicating promising clinical potential for prevention of post-interventional remodeling by abatacept.

Inhibition of intraplaque haemorrhage by controlling neovessels maturation holds promise to improve plaque stability.

Adenosine-to-inosine (A-to-I) editing in the seed sequence of microRNAs can shift the microRNAs’ targetomes and thus their function. Using public RNA-sequencing data, we identified 35 vasoactive microRNAs that are A-to-I edited. We quantified A-to-I editing of the primary (pri-)microRNAs in vascular fibroblasts and endothelial cells. Nine pri-microRNAs were indeed edited, and editing consistently increased under ischemia. We determined mature microRNA editing for the highest expressed microRNAs, i.e., miR-376a-3p, miR-376c-3p, miR-381-3p, and miR-411-5p. All four mature microRNAs were edited in their seed sequence. We show that both ADAR1 and ADAR2 (adenosine deaminase acting on RNA 1 and RNA 2) can edit pri-microRNAs in a microRNA-specific manner. MicroRNA editing also increased under ischemia in vivo in a murine hindlimb ischemia model and ex vivo in human veins. For each edited microRNA, we confirmed a shift in targetome. Expression of the edited microRNA targetomes, not the wild-type targetomes, was downregulated under ischemia in vivo . Furthermore, microRNA editing enhanced angiogenesis in vitro and ex vivo . In conclusion, we show that microRNA A-to-I editing is a widespread phenomenon, induced by ischemia. Each editing event results in a novel microRNA with a unique targetome, leading to increased angiogenesis.

ObjectiveGenetic P300/CBP-associated factor (PCAF) variation affects restenosis-risk in patients. PCAF has lysine acetyltransferase activity and promotes nuclear factor kappa-beta (NFκB)-mediated inflammation, which drives post-interventional intimal hyperplasia development. We studied the contributing role of PCAF in post-interventional intimal hyperplasia.Methods and resultsPCAF contribution to inflammation and intimal hyperplasia was assessed in leukocytes, macrophages and vascular smooth muscle cells (vSMCs) in vitro and in a mouse model for intimal hyperplasia, in which a cuff is placed around the femoral artery. PCAF deficiency downregulate CCL2, IL-6 and TNF-alpha expression, as demonstrated on cultured vSMCs, leukocytes and macrophages. PCAF KO mice showed a 71.8% reduction of vSMC-rich intimal hyperplasia, a 73.4% reduction of intima/media ratio and a 63.7% reduction of luminal stenosis after femoral artery cuff placement compared to wild type (WT) mice. The association of PCAF and vascular inflammation was further investigated using the potent natural PCAF inhibitor garcinol. Garcinol treatment reduced CCL2 and TNF-alpha expression, as demonstrated on cultured vSMCs and leukocytes.To assess the effect of garcinol treatment on vascular inflammation we used hypercholesterolemic ApoE*3-Leiden mice. After cuff placement, garcinol treatment resulted in reduced arterial leukocyte and macrophage adherence and infiltration after three days compared to untreated animals.ConclusionsThese results identify a vital role for the lysine acetyltransferase PCAF in the regulation of local inflammation after arterial injury and likely the subsequent vSMC proliferation, responsible for intimal hyperplasia.