Objective— The purpose of this study was to test the hypothesis that ACE2 overexpression may enhance atherosclerotic plaque stability by antagonizing ACE activity and converting angiotensin II to angiotensin 1–7. Methods and Results— Atherosclerotic plaques were induced in the abdominal aorta of 114 rabbits by endothelial injury and atherogenic diet. Gene therapy was performed in group A at week 4 and in group B at week 12, respectively. Each group of rabbits were randomly divided into 3 subgroups which received, respectively, a recombinant ACE2 expressing vector (AdACE2), a control vector AdEGFP and AdACE2+A779, an antagonist of angiotensin 1–7 receptor. Local ACE2 overexpression attenuated the progression of lesions from week 4 to week 8, but not progression of plaque size from week 12 to week 16. In group B rabbits, local ACE2 overexpression resulted in stable plaque compositions, ie, fewer macrophages, less lipid deposition and more collagen contents, higher plaque stability scores, decreased angiotensin II levels, and increased angiotensin 1–7 levels in plaque tissues in the AdACE2 subgroup compared with those in the AdEGFP subgroup. Conclusions— Overexpression of ACE2 results in stabilized atherosclerotic plaques and the mechanism is probably the conversion of vasoconstrictive angiotensin II to vessel protective angiotensin 1–7.

The reduced expression of angiotensin-converting enzyme (ACE) 2 in the kidneys of animal models and patients with diabetes suggests ACE2 involvement in diabetic nephrology. To explore the renoprotective effects of ACE2 overexpression, ACE inhibition (ACEI) or both on diabetic nephropathy and the potential mechanisms involved, 50 Wistar rats were randomly divided into a normal group that received an injection of sodium citrate buffer and a diabetic model group that received an injection of 60 mg/kg streptozotocin. Eight wks after streptozotocin injection, the diabetic rats were divided into no treatment group, adenoviral (Ad)-ACE2 group, Ad-green flurescent protein (GFP) group, ACEI group receiving benazepril and Ad-ACE2 + ACEI group. Four wks after treatment, physical, biochemical, and renal functional and morphological parameters were measured. An experiment in cultured glomerular mesangial cells was performed to examine the effects of ACE2 on cellular proliferation, oxidative stress and collagen IV synthesis. In comparison with the Ad-GFP group, the Ad-ACE2 group exhibited reduced systolic blood pressure, urinary albumin excretion, creatinine clearance, glomeruli sclerosis index and renal malondialdehyde level; downregulated transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF) and collagen IV protein expression; and increased renal superoxide dismutase activity. Ad-ACE2 and ACEI had similar effects, whereas combined use of Ad-ACE2 and ACEI offered no additional benefits. ACE2transfection attenuated angiotensin (Ang) II-induced glomerular mesangial cell proliferation, oxidative stress and collagen IV protein synthesis. In conclusion, ACE2 exerts a renoprotective effect similar to that of ACEI treatment. Decreased renal Ang II, increased renal Ang-(1–7) levels, and inhibited oxidative stress were the possible mechanisms involved.

Angiotensin-converting enzyme 2 (ACE2) is a newly discovered homolog of ACE whose actions oppose those of angiotensin II (AngII). However, the underlying mechanisms by which ACE2 effectively suppresses early atherosclerotic lesions remain poorly understood. Here, we show, both in vitro and in vivo, that ACE2 inhibited the development of early atherosclerotic lesions by suppressing the growth of vascular smooth muscle cells (VSMCs) and improving endothelial function. In a relatively large cohort animal study (66 rabbits), aortic segments transfected by Ad-ACE2 showed significantly attenuated fatty streak formation, neointimal macrophage infiltration, and alleviation of impaired endothelial function. Segments also showed decreased expression of monocyte chemoattractant protein 1, lectin-like oxidized low-density lipoprotein receptor 1, and proliferating cell nuclear antigen, which led to the delayed onset of atherosclerotic lesions. At the cellular level, ACE2 significantly modulated AngII-induced growth and migration in human umbilical vein endothelial cells and VSMCs. The antiatherosclerotic effect of ACE2 involved down-regulation of the ERK-p38, JAK-STAT, and AngII-ROS-NF-κB signaling pathways and up-regulation of the PI3K-Akt pathway. These findings revealed the molecular mechanisms of the antiatherosclerotic activity of ACE2 and suggested that modulation of ACE2 could offer a therapeutic option for treating atherosclerosis.

Heart failure with preserved ejection fraction (HFpEF) is associated with endothelial dysfunction. We have previously reported that statins prevent endothelial dysfunction through inhibition of microRNA-133a (miR-133a). This study is to investigate the effects and the underlying mechanisms of statins on HFpEF. Here, we show that statins upregulate the expression of a circular RNA (circRNA-RBCK1) which is co-transcripted with the ring-B-box-coiled-coil protein interacting with protein kinase C-1 (RBCK1) gene. Simultaneously, statins increase activator protein 2 alpha (AP-2α) transcriptional activity and the interaction between circRNA-RBCK1 and miR-133a. Furthermore, AP-2α directly interacts with RBCK1 gene promoter in endothelial cells. In vivo, lovastatin improves diastolic function in male mice under HFpEF, which is abolished by loss function of endothelial AP-2α or circRNA-RBCK1. This study suggests that statins upregulate the AP-2α/circRNA-RBCK1 signaling to suppress miR-133a in cardiac endothelial cells and prevent diastolic dysfunction in HFpEF.

Moderate autophagy can remove damaged proteins and organelles. In some inflammatory diseases, autophagy plays a protective role by inhibiting the NOD-like receptor family pyrin domain containing 3(NLRP3). (Pro)renin receptor (PRR, or ATP6AP2) is a critical component of the V-ATPase required for autophagy. It remains controversial about ATP6AP2 in the pathological process. The impact of ATP6AP2 on NLRP3 inflammasome and autophagic flux remains unknown under pressure overload stress. This research explores the potential link between ATP6AP2, autophagic flux, and NLRP3. There was upregulation of ATP6AP2 from 5-day post-TAC, and this expression remained at a high level until 8-weeks post-TAC in wild mice. Meanwhile, autophagic flux switched from early compensatory activation to blocking in the heart failure phase. NLRP3 activation can be seen at 8-week post-TAC. Adenovirus-mediated knockdown of ATP6AP2(shR-ATP6AP2) accelerated the progress of heart failure. After TAC was induced, shR-ATP6AP2 significantly deteriorated heart function and fibrosis compared with the shR-Scr group. Meanwhile, there was an elevated expression of NLRP3 and autophagic flux blockage. A transgenic mouse(Tg) with cardio-restricted ATP6AP2/(P)RR overexpression was constructed. Although high expression in cardiac tissue, there were no spontaneous functional abnormalities under the basal state. Cardiac function, fibrosis, hypertrophy remained identical to the control TAC group. However, SQSTM1/P62 was reduced, which indicated the relief of autophagic flux blockage. Further, Neonatal rat ventricular myocyte (NRVMs) transfected with shR-ATP6AP2 showed more susceptibility than sh-Scr NRVMs to phenylephrine-induced cell death. More reactive oxygen species (ROS) or mito-ROS accumulated in the shR-ATP6AP2 group when phenylephrine stimulation. Blocking NLRP3 activation in vivo partly rescued cardiac dysfunction and fibrosis. In conclusion, ATP6AP2 upregulation is a compensatory response to pressure overload. If not effectively compensated, it compromises autophagic flux, leads to dysfunctional mitochondria accumulation, further produces ROS to activate NLRP3, eventually accelerates heart failure.