Yong-Jie Wu

Effects of fasudil on early atherosclerotic plaque formation and established lesion progression in apolipoprotein E-knockout mice

Rho kinases have been shown to be involved in the pathogenesis of atherosclerosis. This study examined the effects of fasudil, a specific Rho kinase inhibitor, on plaque development and progression in atherosclerotic mice. Sixty apolipoprotein E-knockout (apoE-KO) mice were fed a high-fat diet. Mice started to receive fasudil at the same time as fat feeding (early treatment), or after 12 weeks of fat feeding (delayed treatment). In each administrative schedule, mice were divided into three groups: low dose fasudil group (30 mg/kg/day), high dose fasudil group (100mg/kg/day) and control group (tap water) (n=10, respectively). Plaque size was determined by using ultrasound biomicroscopy (UBM) and histological examinations. Brachiocephalic artery UBM analysis showed that in early treatment, both doses of fasudil significantly reduced lesion size compared with the controls (P<0.05). In delayed-fasudil treatment, plaque area was reduced by 54% (P<0.05) after 12 weeks of treatment at a high dose of fasudil (100mg/kg/day). The UBM findings were confirmed by histological studies at the corresponding arterial sites. The beneficial effect was also observed in the left common carotid arteries that delayed-fasudil treatment reduced the plaque size in a dose-dependent manner. The arterial intima-medial thickness (IMT) and maximal flow velocity of both arteries were lower in fasudil-treated group (100mg/kg/day) in comparison with the control mice. Furthermore, fasudil treatment (100mg/kg/day) reduced the macrophage accumulation in atherosclerotic lesions. However, fasudil had no effects on blood pressure and plasma lipid concentrations in both studies. In conclusion, our studies showed that blocking Rho kinase reduced both the early development and later progression of atherosclerotic plaques in apoE-KO mice by using a novel micro-ultrasound approach.

Complement-Mediated Macrophage Polarization in Perivascular Adipose Tissue Contributes to Vascular Injury in Deoxycorticosterone Acetate–Salt Mice

Objective— We have previously shown an increased expression of complement 3 (C3) in the perivascular adipose tissue (PVAT) in the deoxycorticosterone acetate (DOCA)–salt hypertensive model. This study aims to examine the role and underlying mechanism of C3 in PVAT for understanding the pathogenesis of hypertensive vascular remodeling further. Approach and Results— The role of C3 in macrophage polarization was investigated using peritoneal macrophages from wild-type and C3-deficient (C3KO) mice because we found that C3 was primarily expressed in macrophages in PVAT of blood vessels from DOCA-salt mice, and results showed a decreased expression of M1 phenotypic marker in contrast to an increased level of M2 marker in the C3KO macrophages. Bone marrow transplantation studies further showed in vivo that DOCA-salt recipient mice had fewer M1 but more M2 macrophages in PVAT when the donor bone marrows were from C3KO compared with those from wild-type mice. Of note, this macrophage polarization shift was accompanied with an ameliorated vascular injury. Furthermore, we identified the complement 5a (C5a) as the major C3 activation product that was involved in macrophage polarization and DOCA-salt–induced vascular injury. Consistently, in vivo depletion of macrophages prevented the induction of C3 and C5a in PVAT, and ameliorated hypertensive vascular injury as well. Conclusions— The presence and activation of bone marrow–derived macrophages in PVAT are crucial for complement activation in hypertensive vascular inflammation, and C5a plays a critical role in DOCA-salt–induced vascular injury by stimulating macrophage polarization toward a proinflammatory M1 phenotype in PVAT.

CHANGES IN THE COMPOSITION OF THE THORACIC AORTIC WALL IN SPONTANEOUSLY HYPERTENSIVE RATS TREATED WITH LOSARTAN OR SPIRONOLACTONE

1 In the present study, we compared the elastin and collagen content of thoracic aortic medial and adventitial layers from Wistar‐kyoto (WKY) and spontaneously hypertensive rats (SHR). In addition, the effects of losartan, an angiotensin II receptor antagonist, and spironolactone, a mineralocorticoid receptor antagonist, on collagen and elastin content were determined. 2 Prehypertensive (4‐week‐old) and hypertensive (16‐week‐old) SHR were randomly divided into three groups treated with either 0.9% NaCl, losartan (20 mg/kg per day) or spironolactone (200 mg/kg per day). Prehypertensive and hypertensive SHR were treated for 12 and 16 weeks, respectively. Age‐matched WKY rats were not treated with NaCl, losartan or spironolactone and served as the control group. 3 The medial and adventitial layers of the thoracic aorta were composed mainly of elastin and collagen, respectively, in both SHR and WKY rats. Compared with WKY rats, SHR exhibited greater collagen and elastin content in the media, but decreased collagen and elastin content in the adventitial layer. Both medial and adventitial collagen and elastin content increased significantly with age in both strains and was greater in 32‐week‐old rats compared with 16‐week‐old rats. Spironolactone treatment decreased collagen content in the media of thoracic aortas from prehypertensive SHR, whereas losartan decreased collagen content in the media of aortas from hypertensive SHR. In contrast, neither spironolactone nor losartan had any effect on adventitial collagen content in prehypertensive and hypertensive SHR. Medial collagen and elastin were positively related to pulse pressure (PP), but there was no correlation between adventitial mass or collagen content and PP or mean arterial pressure in untreated and treated SHR and WKY rats. 4 In conclusion, the composition of the medial and adventitial layers of the thoracic aorta differs and treatment of SHR with losartan and spironolactone decreases collagen content when delivered at the hypertensive or prehypertensive stage, respectively. However, neither drug has any effect on adventitial collagen content in SHR.

Renal denervation attenuates aldosterone expression and associated cardiovascular pathophysiology in angiotensin II-induced hypertension.

The sympathetic nervous system interacts with the renin-angiotensin-aldosterone system (RAAS) contributing to cardiovascular diseases. In this study, we sought to determine if renal denervation (RDN) inhibits aldosterone expression and associated cardiovascular pathophysiological changes in angiotensin II (Ang II)-induced hypertension. Bilateral RDN or SHAM operation was performed before chronic 14-day Ang II subcutaneous infusion (200ng/kg/min) in male Sprague-Dawley rats. Bilateral RDN blunted Ang II-induced hypertension and ameliorated the mesenteric vascular dysfunction. Cardiovascular hypertrophy in response to Ang II was significantly attenuated by RDN as shown by histopathology and transthoracic echocardiography. Moreover, Ang II-induced vascular and myocardial inflammation and fibrosis were suppressed by RDN with concurrent decrease in fibronectin and collagen deposition, macrophage infiltration, and MCP-1 expression. Interestingly, RDN also inhibited Ang II-induced aldosterone expression in the plasma, kidney and heart. This was associated with the reduction of calcitonin gene-related peptide (CGRP) in the adrenal gland. Ang II promoted aldosterone secretion which was partly attenuated by CGRP in the adrenocortical cell line, suggesting a protective role of CGRP in this model. Activation of transforming growth factor-β (TGF-β)/Smad and mitogen-activated protein kinases (MAPKs) signaling pathway was both inhibited by RDN especially in the heart. These results suggest that the regulation of the renal sympathetic nerve in Ang II-induced hypertension and associated cardiovascular pathophysiological changes is likely mediated by aldosterone, with CGRP involvement.

Ca(2+)-regulated lysosome fusion mediates angiotensin II-induced lipid raft clustering in mesenteric endothelial cells.

It has been reported that intracellular Ca2+ is involved in lysosome fusion and membrane repair in skeletal cells. Given that angiotensin II (Ang II) elicits an increase in intracellular Ca2+ and that lysosome fusion is a crucial mediator of lipid raft (LR) clustering, we hypothesized that Ang II induces lysosome fusion and activates LR formation in rat mesenteric endothelial cells (MECs). We found that Ang II acutely increased intracellular Ca2+ content, an effect that was inhibited by the extracellular Ca2+ chelator ethylene glycol tetraacetic acid (EGTA) and the inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release inhibitor 2-aminoethoxydiphenyl borate (2-APB). Further study showed that EGTA almost completely blocked Ang II-induced lysosome fusion, the translocation of acid sphingomyelinase (ASMase) to LR clusters, ASMase activation and NADPH (nicotinamide adenine dinucleotide phosphate) oxidase activation. In contrast, 2-APB had a slight inhibitory effect. Functionally, both the lysosome inhibitor bafilomycin A1 and the ASMase inhibitor amitriptyline reversed Ang II-induced impairment of vasodilation. We conclude that Ca2+-regulated lysosome fusion mediates the Ang II-induced regulation of the LR-redox signaling pathway and mesenteric endothelial dysfunction.

Effect of Hirulog-Like Peptide on Balloon Catheter Injury-Induced Neointimal Formation in Femoral Arteries of Minipigs and Relationship with Inflammatory Mediators

Vascular intervention-induced neointimal formation is a major drawback for managing atherosclerotic cardiovascular diseases using invasive vascular procedures. Our previous studies demonstrated that hirulog-like peptide (HLP) reduced balloon catheter dilation-induced neointimal formation or restenosis in carotid arteries of rats or atherosclerotic rabbits with less interruption in coagulation or bleeding than heparin or hirulog-1. The present study examined the effect of HLP on balloon catheter injury-induced neointimal formation in femoral arteries of minipigs. Intravenous infusion of HLP (1.6 mg/kg/h for 4 h started 0.5 h before the intervention) or unfractured heparin (50 U/kg/h for 4 h) significantly reduced neointimal formation in femoral arteries 4 weeks after intervention compared with the vehicle. Heparin, but not HLP, significantly prolonged activated partial thromboplastin time. HLP or heparin significantly reduced vascular intervention-induced increases in C-reactive protein, P-selectin and interleukin-6 in serum. HLP, but not heparin, normalized vascular injury-induced increase in P-selectin in platelets. The results of the present study suggest that HLP is an effective agent for preventing balloon catheter injury-induced neointimal formation in femoral arteries of minipigs. The beneficial effects of HLP on vascular injury-induced neointimal formation may partially result from its inhibition on inflammatory mediators.

Membrane rafts–redox signalling pathway contributes to renal fibrosis via modulation of the renal tubular epithelial–mesenchymal transition

Membrane rafts (MRs)–redox signalling pathway is activated in response to transforming growth factor‐β1 (TGF‐β1) stimulation in renal tubular cells. This pathway contributes to TGF‐1β‐induced epithelial–mesenchymal transition (EMT) in renal tubular cells. The the MRs–redox signalling pathway is activated in renal tubular cells isolated from angiotensin II (AngII)‐induced hypertensive rats. Inhibition of this pathway attenuated renal inflammation and fibrosis in AngII‐induced hypertension.