Angiotensin II induces MMP-2 in a p47phox-dependent manner

The role of oxidative stress in aortic dissection: a potential therapeutic target

The incidence of aortic dissection (AD) is steadily increasing, driven by the rising prevalence of chronic conditions such as hypertension and the global aging of the population. Oxidative stress emerges as a pivotal pathophysiological mechanism contributing to the progression of AD. Oxidative stress triggers apoptosis in vascular smooth muscle cells, reshapes the extracellular matrix (ECM), and governs ECM degradation and remodeling, subsequently impacting aortic compliance. Furthermore, oxidative stress not only facilitates the infiltration of macrophages and mononuclear lymphocytes but also disrupts the integral structure and functionality of endothelial cells, thereby inducing endothelial cell dysfunction and furthering the degeneration of the middle layer of the aortic wall. Investigating antioxidants holds promise as a therapeutic avenue for addressing AD.

Effects of once-weekly glucagon-like peptide-1 receptor agonists on type 2 diabetes mellitus complicated with coronary artery disease: Potential role of the renin-angiotensin system

AIM

To investigate the potential mechanism of once-weekly glucagon-like peptide-1 receptor agonists (GLP-1 RA) in the treatment of type 2 diabetes mellitus (T2DM) complicated with coronary artery disease (CAD).

METHODS

We searched both Chinese and English databases for randomized controlled trials related to once-weekly GLP-1 RA for T2DM complicated with CAD to verify the safety and efficacy of GLP-1 RA. The underlying mechanism was analysed by network pharmacology.

RESULTS

In total, 13 studies with 35 563 participants were included in the analysis. The pooled analysis found that dulaglutide, exenatide and semaglutide outperformed placebo in cardiovascular outcomes in patients with T2DM, with a significant reduction in the incidence of non-fatal stroke (p < .00). Levels of cardiovascular risk factors were significantly reduced in the once-weekly GLP-1 RA group compared with the conventional treatment group (glycated haemoglobin: p < .00; fasting blood glucose: p < .00; weight: p < .00; systolic blood pressure: p < .00; total cholesterol: p < .00; low-density lipoprotein cholesterol: p < .00). Network pharmacology results were enriched to the renin-angiotensin system, and matrix metalloproteinase 2 and renin (REN) may be the key targets. In addition, four key targets of dulaglutide, five key targets of exenatide and two key targets of semaglutide were enriched.

CONCLUSIONS

Our study suggests that once-weekly GLP-1 RA may have a potential protective effect on cardiovascular events in patients with T2DM combined with CAD, possibly through the renin-angiotensin system. However, further research is needed to confirm these findings and determine cause and effect.

Role of Matrix Metalloproteinase-2 in the Development of Atherosclerosis among Patients with Coronary Artery Disease

Coronary artery disease (CAD) is a caused by atherosclerotic plaque buildup in the coronary arteries that supply blood and oxygen to the heart. Matrix metalloproteinase (MMP) is a family of zinc-dependent endopeptidase that is involved in various stages of atherosclerosis as demonstrated in in vitro and in vivo studies. MMP-2 is associated with both stable and unstable atherosclerotic plaque formation. The current review aimed to identify the role of MMP-2 in atherosclerosis development among CAD patients. Literature search was conducted through four online databases and only studies that were published from 2018 until February 2023 were included. The risk of bias was assessed by using the Newcastle-Ottawa Scale. A total of 10,622 articles were initially identified, and only eight studies that fulfilled the selection criteria were included in this review. The results showed that MMP-2 levels and activity were higher in patients with unstable CAD than those with stable CAD and healthy subjects. There was a significant association between MMP-2 levels and cardiovascular disease with MMP-14 levels, which is a pro-MMP-2 activator. In addition, two single nucleotide polymorphisms of the MMP-2 gene (rs243865 and rs243866) were significantly associated with the development of atherosclerosis. In conclusion, MMP-2 plays a crucial role in the development of atherosclerosis among patients with CAD and could be a potential target for CAD therapy.

Reactive Oxygen Species Induced Pathways in Heart Failure Pathogenesis and Potential Therapeutic Strategies

With respect to structural and functional cardiac disorders, heart failure (HF) is divided into HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). Oxidative stress contributes to the development of both HFrEF and HFpEF. Identification of a broad spectrum of reactive oxygen species (ROS)-induced pathways in preclinical models has provided new insights about the importance of ROS in HFrEF and HFpEF development. While current treatment strategies mostly concern neuroendocrine inhibition, recent data on ROS-induced metabolic pathways in cardiomyocytes may offer additional treatment strategies and targets for both of the HF forms. The purpose of this article is to summarize the results achieved in the fields of: (1) ROS importance in HFrEF and HFpEF pathophysiology, and (2) treatments for inhibiting ROS-induced pathways in HFrEF and HFpEF patients. ROS-producing pathways in cardiomyocytes, ROS-activated pathways in different HF forms, and treatment options to inhibit their action are also discussed.

The Impact of microRNAs in Renin-Angiotensin-System-Induced Cardiac Remodelling

Current knowledge on the renin-angiotensin system (RAS) indicates its central role in the pathogenesis of cardiovascular remodelling via both hemodynamic alterations and direct growth and the proliferation effects of angiotensin II or aldosterone resulting in the hypertrophy of cardiomyocytes, the proliferation of fibroblasts, and inflammatory immune cell activation. The noncoding regulatory microRNAs has recently emerged as a completely novel approach to the study of the RAS. A growing number of microRNAs serve as mediators and/or regulators of RAS-induced cardiac remodelling by directly targeting RAS enzymes, receptors, signalling molecules, or inhibitors of signalling pathways. Specifically, microRNAs that directly modulate pro-hypertrophic, pro-fibrotic and pro-inflammatory signalling initiated by angiotensin II receptor type 1 (AT1R) stimulation are of particular relevance in mediating the cardiovascular effects of the RAS. The aim of this review is to summarize the current knowledge in the field that is still in the early stage of preclinical investigation with occasionally conflicting reports. Understanding the big picture of microRNAs not only aids in the improved understanding of cardiac response to injury but also leads to better therapeutic strategies utilizing microRNAs as biomarkers, therapeutic agents and pharmacological targets.

Mst1/2 Kinases Inhibitor, XMU-MP-1, Attenuates Angiotensin II-Induced Ascending Aortic Expansion in Hypercholesterolemic Mice

Background: Ascending and abdominal aortic aneurysms (AAs) are asymptomatic, permanent dilations of the aorta with surgical intervention as the currently available therapy. Hippo-Yap signaling cascade plays a critical role in stem cell self-renewal, tissue regeneration and organ size control. By using XMU-MP-1, a pharmacological inhibitor of the key component of Hippo-Yap signaling, MST1/2, we examined the functional contribution of Hippo-Yap in the development of AAs in Angiotensin II (AngII)-infused hypercholesterolemic mice.

Methods and Results: MST, p-MST, p-YAP, p-MOB and TAZ proteins in AngII-infused ascending and abdominal aortas were assessed by immunohistochemical and western blot analyses. To examine the effect of MST1/2 inhibition on AAs, western diet-fed low density lipoprotein (LDL) receptor −/− mice infused with AngII were administered with either vehicle or XMU-MP-1 for 5 weeks. Hippo-YAP signaling proteins were significantly elevated in AngII infused ascending and abdominal aortas. XMU-MP-1 administration resulted in the attenuation of AngII-induced ascending AAs without influencing abdominal AAs and aortic atherosclerosis. Inhibition of Hippo-YAP signaling also resulted in the suppression of AngII-induced matrix metalloproteinase 2 (MMP2) activity, macrophage accumulation, aortic medial hypertrophy and elastin breaks in the ascending aorta.

Conclusions: The present study demonstrates a pivotal role for the Hippo-YAP signaling pathway in AngII-induced ascending AA development.

Genistein Prevents Nitric Oxide Deficiency-Induced Cardiac Dysfunction and Remodeling in Rats

Genistein is an isoflavone found in soybeans. This study evaluates the protective effects of genistein on N^ω-nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced hypertension, cardiac remodeling, and dysfunction in rats. Male Wistar rats were treated with L-NAME 40 mg/kg/day together for 5 weeks, with or without genistein at a dose of 40 or 80 mg/kg/day or lisinopril 5 mg/kg/day (n = 8 per group). Genistein prevented L-NAME-induced hypertension in rats. Increases in the left ventricular weight, metalloproteinase-2, metalloproteinase-9, and collagen type I intensity were observed in L-NAME rats, and these changes were attenuated in the genistein-treated group. Genistein reduced circulating angiotensin-converting enzyme activity and angiotensin II concentrations in L-NAME rats. L-NAME increased plasma and cardiac malondialdehyde and vascular superoxide generations, as well as reductions of serum and cardiac catalase activities in rats. Plasma nitrate/nitrite were protected in the genistein-treated group. Genistein prevented the L-NAME-induced overexpression of angiotensin II receptor type I (AT₁R), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit 2 (gp91^phox), and transforming growth factor beta I (TGF-β1) in hypertensive rats. In conclusion, genistein exhibited a cardioprotective effect in hypertensive rats in this study. The molecular mechanisms might be mediated by suppression of oxidative stress through the Ang II/AT₁R/NADPH oxidase/TGF-β1 signaling pathway.

Antiaging Activity of Peptide Identified from Fermented Trapa Japonica Fruit Extract in Human Dermal Fibroblasts

We have previously shown that Trapa japonica fruit extract (TJE) as well as its fermented extract (FTJ) can be potentially used to treat alopecia. In the current study, a newly synthesized peptide (PEP) was detected in an active compound isolated from FTJ. Several biological assays were conducted to verify the antiaging effects of TJE, FTJ, and PEP on the skin. We examined the effects of TJE, FTJ, and PEP on cell viability, collagen synthesis, and inhibition of mRNA expression of matrix metalloproteinases (MMPs), induced by tumor necrosis factor alpha (TNF-α), in human dermal fibroblasts (HDFs). In addition, a wound-healing assay of the human keratinocyte cell line (HaCaT) and a clinical study of antiaging activity were conducted. The findings confirmed that PEP exerted an effect on cell proliferation in a dose-dependent manner. Treatment with TJE, FTJ, and PEP increased collagen synthesis but inhibited TNF-α-induced mRNA expression of MMPs. Compared with TJE and FTJ, PEP promoted a significant level of wound recovery in HaCaT cells and also exhibited antiaging effect, as demonstrated by a clinical study. These results suggest that PEP shows potential as a skin antiaging cosmetic product.

Redox control of vascular biology

Redox control is lost when the antioxidant defense system cannot remove abnormally high concentrations of signaling molecules, such as reactive oxygen species (ROS). Chronically elevated levels of ROS cause oxidative stress that may eventually lead to cancer and cardiovascular and neurodegenerative diseases. In this review, we focus on redox effects in the vascular system. We pay close attention to the subcompartments of the vascular system (endothelium, smooth muscle cell layer) and give an overview of how redox changes influence those different compartments. We also review the core aspects of redox biology, cardiovascular physiology, and pathophysiology. Moreover, the topic-specific knowledgebase DES-RedoxVasc was used to develop two case studies, one focused on endothelial cells and the other on the vascular smooth muscle cells, as a starting point to possibly extend our knowledge of redox control in vascular biology.

Matrix metalloproteinase-2 knockout prevents angiotensin II-induced vascular injury

Aims

Matrix metalloproteinases (MMPs) have been implicated in the development of hypertension in animal models and humans. Mmp2 deletion did not change Ang II-induced blood pressure (BP) rise. However, whether Mmp2 knockout affects angiotensin (Ang) II-induced vascular injury has not been tested. We sought to determine whether Mmp2 knockout will prevent Ang II-induced vascular injury.

Methods and results

A fourteen-day Ang II infusion (1000 ng/kg/min, SC) increased systolic BP, decreased vasodilatory responses to acetylcholine, induced mesenteric artery (MA) hypertrophic remodelling, and enhanced MA stiffness in wild-type (WT) mice. Ang II enhanced aortic media and perivascular reactive oxygen species generation, aortic vascular cell adhesion molecule-1 and monocyte chemotactic protein-1 expression, perivascular monocyte/macrophage and T cell infiltration, and the fraction of spleen activated CD4+CD69+ and CD8+CD69+ T cells, and Ly-6Chi monocytes. Study of intracellular signalling showed that Ang II increased phosphorylation of epidermal growth factor receptor and extracellular-signal-regulated kinase 1/2 in vascular smooth muscle cells isolated from WT mice. All these effects were reduced or prevented by Mmp2 knockout, except for systolic BP elevation. Ang II increased Mmp2 expression in immune cells infiltrating the aorta and perivascular fat. Bone marrow (BM) transplantation experiments revealed that in absence of MMP2 in immune cells, Ang II-induced BP elevation was decreased, and that when MMP2 was deficient in either immune or vascular cells, Ang II-induced endothelial dysfunction was blunted.

Conclusions

Mmp2 knockout impaired Ang II-induced vascular injury but not BP elevation. BM transplantation revealed a role for immune cells in Ang II-induced BP elevation, and for both vascular and immune cell MMP2 in Ang II-induced endothelial dysfunction.

Carthamus tinctorius L. extract improves hemodynamic and vascular alterations in a rat model of renovascular hypertension through Ang II-AT1R-NADPH oxidase pathway

Carthamus tinctorius L. (CT) is widely used in Asian countries as a beverage and in folk medicine. The effects of CT extract on hemodynamics, vascular remodeling, the renin-angiotensin system (RAS) and oxidative stress in the two-kidney, one clip (2K-1C) hypertensive rat model were investigated. Renovascular hypertension was induced in male Sprague-Dawley rats and were treated with CT extract (500mg/kg/day) or captopril (5mg/kg/day) or vehicle for four weeks. CT extract or captopril reduced blood pressure, hindlimb vascular resistance, and increased hindlimb blood flow in 2K-1C hypertensive rats (p<0.05). Increases in aortic wall thickness, cross-sectional area and collagen deposition in 2K-1C rats were alleviated with CT extract or captopril treatment (p<0.05). CT extract or captopril suppressed RAS activation, including elevated serum ACE activity, and plasma Ang II level and up-regulated aortic AT1R protein expression in 2K-1C rats (p<0.05). Furthermore, CT extract or captopril reduced vascular superoxide production, aortic NADPH oxidase subunit gp91phox expression and increased plasma nitric oxide metabolite levels in 2K-1C rats (p<0.05). These findings suggest that CT extract ameliorated hemodynamic alteration and vascular remodeling in 2K-1C hypertensive rats. Possible mechanisms may involve RAS inhibitor effects and potent antioxidant activity.

Extracellular Matrix Metalloproteinase Inducer EMMPRIN (CD147) in Cardiovascular Disease

The receptor EMMPRIN is involved in the development and progression of cardiovascular diseases and in the pathogenesis of myocardial infarction. There are several binding partners of EMMPRIN mediating the effects of EMMPRIN in cardiovascular diseases. EMMPRIN interaction with most binding partners leads to disease progression by mediating cytokine or chemokine release, the activation of platelets and monocytes, as well as the formation of monocyte-platelet aggregates (MPAs). EMMPRIN is also involved in atherosclerosis by mediating the infiltration of pro-inflammatory cells. There is also evidence that EMMPRIN controls energy metabolism of cells and that EMMPRIN binding partners modulate intracellular glycosylation and trafficking of EMMPRIN towards the cell membrane. In this review, we systematically discuss these multifaceted roles of EMMPRIN and its interaction partners, such as Cyclophilins, in cardiovascular disease.

Deletion of NF-κB/RelA in Angiotensin II-Sensitive Mesenchymal Cells Blocks Aortic Vascular Inflammation and Abdominal Aortic Aneurysm Formation

OBJECTIVE

Infusion of angiotensin II (Ang II) induces extracellular matrix remodeling and inflammation resulting in abdominal aortic aneurysms (AAAs) in normolipidemic mice. Although Ang II activates mesenchymal cells in the media and adventitia to become fibrogenic, the sentinel role of this mesenchymal population in modulating the inflammatory response and aneurysms is not known. We test the hypothesis that these fibrogenic mesenchymal cells play a critical role in Ang II-induced aortic wall vascular inflammation and AAA formation.

APPROACH AND RESULTS

Ang II infusion increased phospho-Ser536-RelA and interleukin (IL)-6 immunostaining in the abdominal aorta. In addition, aortic mRNA transcripts of RelA-dependent cytokines IL-6 and IL-1β were significantly elevated suggesting that Ang II functionally activates RelA signaling. To test the role of mesenchymal RelA in AAA formation, we generated RelA-CKO mice by administering tamoxifen to double transgenic mice harboring RelA-flox alleles and tamoxifen-inducible Col1a2 promoter-driven Cre recombinase (Col1a2-CreER^T). Tamoxifen administration to Col1a2-CreER^T•mT/mG mice induced Cre expression and RelA depletion in aortic smooth muscle cells and fibroblasts but not in endothelial cells. Infusion of Ang II significantly increased abdominal aortic diameter and the incidence of AAA in RelA wild-type but not in RelA-CKO mice, independent of changes in systolic blood pressure. Furthermore, mesenchymal cell-specific RelA-CKO mice exhibited decreased expression of IL-6 and IL-1β cytokines and decreased recruitment of C68+ and F4/80^lo•Ly6C^hi monocytes during Ang II infusion.

CONCLUSIONS

Fibrogenic mesenchymal RelA plays a causal role in Ang II-induced vascular inflammation and AAA in normolipidemic mice.

Angiotensin-(1-7) regulates angiotensin II-induced matrix metalloproteinase-8 in vascular smooth muscle cells

BACKGROUND AND AIMS

Angiotensin II (Ang II) is a bioactive peptide that is related to cardiovascular disease such as atherosclerosis, whereas angiotensin-(1-7) (Ang-(1-7)) is a counter-regulator of angiotensin II, which protects against cardiovascular disease. Matrix metalloproteinase 8 (MMP-8) is thought to participate in plaque destabilization though degradation of extracellular matrix, improving the development of atherosclerosis. Whether Ang-(1-7) modulates Ang II-induced MMP-8 remains unclear. In this study, we investigated the effect of Ang-(1-7) on Ang II-induced MMP-8 expression in smooth muscle cells.

METHODS

Smooth muscle cells were treated with Ang II, Ang-(1-7) and their antagonists. In addition, ApoE knockout mice were fed a high fat diet and subcutaneously injected with Ang II, Ang-(1-7), Ang II+Ang-(1-7) (±A779).

RESULTS

We found that Ang II increased MMP-8 mRNA and protein expression in vascular smooth muscle cells, while Ang-(1-7) alone had no effect. However, Ang-(1-7) inhibited Ang II-induced MMP-8 expression. The inhibitory effect of Ang-(1-7) could be abolished by the competitive antagonist of Ang-(1-7) at the MAS receptor. Furthermore, Ang II induced p38 MAPK activation, and this was inhibited by the treatment of Ang-(1-7). Ang II-induced MMP-8 expression could be attenuated by the p38 MAPK inhibitor SB203580. Ang-(1-7) also significantly suppressed Ang II-induced MMP-8 in both atherosclerotic plaques and serum in ApoE^-/- mice. The atherosclerotic plaques in mice treated with Ang-(1-7) and Ang II appeared to be more stable with more type I collagen contents than those in mice treated with Ang II.

CONCLUSIONS

Our results suggest that Ang-(1-7) plays an important role in protecting against atherosclerosis via counter-regulation of Ang II-induced MMP-8.

Angiotensin II Induces an Increase in Matrix Metalloproteinase 2 Expression in Aortic Smooth Muscle Cells of Ascending Thoracic Aortic Aneurysms Through JNK, ERK1/2, and p38 MAPK Activation

In this study, we hypothesized that angiotensin II (Ang II) induces matrix metalloproteinase 2 (MMP-2) upregulation in aneurysmal smooth muscle cells (ASMCs) derived from ascending thoracic aortic aneurysms (ATAAs). We compared MMP-2 protein levels in ascending aortic specimens using Western blot and plasma concentrations by enzyme-linked immunosorbent assay between ATAA (n = 40) and coronary heart disease patients (n = 40). Additionally, the protein level of angiotensinogen (AGT) in the ascending aorta and the plasma concentration of Ang II were detected by Western blot and radioimmunoassay, respectively, in ATAA and coronary heart disease patients. In ATAA patients, Ang II and MMP-2 plasma levels were significantly increased (P < 0.05). Additionally, AGT and MMP-2 protein levels in the aorta of ATAA patients were higher (P < 0.01). Enhanced AGT suggested that the amount of Ang II in aneurysmal aorta specimens may be also increased, which was confirmed by immunofluorescent staining for Ang II. Moreover, we investigated the effect of Ang II on MMP-2 upregulation by ASMCs and determined the Ang II receptors and intracellular signaling pathways that are involved. Our results showed that treatment with Ang II significantly increased the expression of MMP-2 through the Ang II type 1 receptor (AT1R) and activated the 3 major mitogen-activated protein kinases (MAPKs), JNK, ERK1/2, and p38 MAPK. In conclusion, these results indicate that Ang II can induce MMP-2 expression elevation through AT1R and MAPK pathways in ASMCs and suggest that there is therapeutic potential for angiotensin receptor blocker drugs and MAPK inhibitors in the prevention and treatment of ATAAs.

Cross talk between MMP2-Spm-Cer-S1P and ERK1/2 in proliferation of pulmonary artery smooth muscle cells under angiotensin II stimulation

The aim of the present study is to establish the mechanism associated with the proliferation of PASMCs under ANG II stimulation. The results showed that treatment of PASMCs with ANG II induces an increase in cell proliferation and 100 nM was the optimum concentration for maximum increase in proliferation of the cells. Pretreatment of the cells with AT1, but not AT2, receptor antagonist inhibited ANG II induced cell proliferation. Pretreatment with pharmacological and genetic inhibitors of sphingomyelinase (SMase) and sphingosine kinase (SPHK) prevented ANG II-induced cell proliferation. ANG II has also been shown to induce SMase activity, SPHK phosphorylation and S1P production. In addition, ANG II caused an increase in proMMP-2 expression and activation, ERK1/2 phosphorylation and NADPH oxidase activation. Upon inhibition of MMP-2, SMase activity and S1P level were curbed leading to inhibition of cell proliferation. SPHK was phosphorylated by ERK1/2 during ET-1 stimulation of the cells. ANG II-induced ERK1/2 phosphorylation and proMMP-2 expression and activation in the cells were abrogated upon inhibition of NADPH oxidase activity. Overall, NADPH oxidase plays an important role in proMMP-2 expression and activation and that MMP-2 mediated SMC proliferation occurs through the involvement of Spm-Cer-S1P signaling axis under ANG II stimulation of PASMCs.

Cross-talk between NADPH oxidase-PKCα-p(38)MAPK and NF-κB-MT1MMP in activating proMMP-2 by ET-1 in pulmonary artery smooth muscle cells

Treatment of bovine pulmonary artery smooth muscle cells with endothelin-1 (ET-1) caused an increase in the expression and activation of proMMP-2 in the cells. The present study was undertaken to determine the underlying mechanisms involved in this scenario. We demonstrated that (i) pretreatment with NADPH oxidase inhibitor, apocynin; PKC-α inhibitor, Go6976; p(38)MAPK inhibitor SB203580 and NF-κB inhibitor, Bay11-7082 inhibited the expression and activation of proMMP-2 induced by ET-1; (ii) ET-1 treatment to the cells stimulated NADPH oxidase and PKCα activity, p(38)MAPK phosphorylation as well as NF-κB activation by translocation of NF-κBp65 subunit from cytosol to the nucleus, and subsequently by increasing its DNA-binding activity; (iii) ET-1 increases MT1-MMP expression, which was inhibited upon pretreatment with apocynin, Go6976, SB293580, and Bay 11-7082; (iv) ET-1 treatment to the cells downregulated TIMP-2 level. Although apocynin and Go6976 pretreatment reversed ET-1 effect on TIMP-2 level, yet pretreatment of the cells with SB203580 and Bay 11-7082 did not show any discernible change in TIMP-2 level by ET-1. Overall, our results suggest that ET-1-induced activation of proMMP-2 is mediated via cross-talk between NADPH oxidase-PKCα-p(38)MAPK and NFκB-MT1MMP signaling pathways along with a marked decrease in TIMP-2 expression in the cells.

Angiotensin II induces an increase in MMP-2 expression in idiopathic ascending aortic aneurysm via AT1 receptor and JNK pathway

The cellular and molecular mechanisms responsible for human idiopathic ascending aortic aneurysm (IAAA) remain unknown. Matrix metalloproteinase-2 (MMP-2) is a key enzyme for the degradation of extracellular matrix in aneurysmal walls. The aim of this study was to elucidate the role of the angiotensin II (Ang II) pathway in MMP-2 induction in IAAA aortic walls. Quantitative polymerase chain reaction and western blot analysis were used to compare the MMP-2 mRNA and protein levels in ascending aortic specimens with those in IAAA patients (n = 10) and heart transplant donors (n = 5) without any aortopathy. It was found that MMP-2 expression was significantly increased, which was associated with elastic lamellae disruption in IAAA walls. Additionally, the expression levels of angiotensinogen (AGT) and Ang II in the ascending aortic tissues from individuals with and without IAAAs were detected by western blot analysis and radioimmunoassay, respectively. The results demonstrated that the expressions of AGT and Ang II protein were significantly increased in the ascending aortic tissues of IAAA patients. Furthermore, whether Ang II induces MMP-2 expression was investigated using human IAAA walls ex vivo culture. It was found that exogenous Ang II increased the MMP-2 expression in a dose-dependent manner, which was completely inhibited by the Ang II type 1 receptor (AT1R) inhibitor candesartan and was mediated by c-Jun N-terminal kinase (JNK) activation. Taken together, these results indicate that Ang II can induce an increase of MMP-2 expression via AT1R and JNK in ex vivo cultured IAAA aortic walls, and suggest that angiotensin receptor blocker (ARB) drugs and JNK inhibitors have the potential in the prevention or treatment of IAAAs.

Angiotensin II increases matrix metalloproteinase 2 expression in human aortic smooth muscle cells via AT1R and ERK1/2

Increased levels of angiotensin II (Ang II) and activated matrix metalloproteinase 2 (MMP-2) produced by human aortic smooth muscle cells (human ASMCs) have recently been implicated in the pathogenesis of thoracic aortic aneurysm (TAA). Additionally, angiotensin II type 1 receptor (AT1R)-mediated extracellular signal-regulated kinase (ERK)1/2 activation contributes to TAA development in Marfan Syndrome. However, there is scant data regarding the relationship between Ang II and MMP-2 expression in human ASMCs. Therefore, we investigated the effect of Ang II on MMP-2 expression in human ASMCs and used Western blotting to identify the Ang II receptors and intracellular signaling pathways involved. Reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence data demonstrated that Ang II receptors were expressed on human ASMCs. Additionally, Ang II increased the expression of Ang II type 2 receptor (AT2R) but not AT1R at both the transcriptional and translational levels. Furthermore, Western blotting showed that Ang II increased MMP-2 expression in human ASMCs in a dose- and time-dependent manner. This response was completely inhibited by the AT1R inhibitor candesartan but not by the AT2R blocker PD123319. In addition, Ang II-induced upregulation of MMP-2 was mediated by the activation of ERK1/2, whereas p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinase (JNK) had no effect on this process. In conclusion, these results indicate that Ang II can increase the expression of MMP-2 via AT1 receptor and ERK1/2 signaling pathways in human ASMCs and suggest that antagonists of AT1R and ERK1/2 may be useful for treating TAAs.

Protective effect of telmisartan on neurovascular unit and inflammasome in stroke-resistant spontaneously hypertensive rats

OBJECTIVES

Hypertension is a crucial risk factor for both stroke and dementia, including Alzheimer's disease (AD). We inspected the effect of telmisartan on the neurovascular unit (NVU) and related inflammatory responses in spontaneously hypertensive rat stroke resistant (SHR-SR) by observing the components of NVU such as N-acetyl glucosamine oligomer (NAGO), collagen IV, astrocytes, and matrix metalloproteinase-9 (MMP-9), as well as inflammasome NOD-like receptors family protein 3 (NLRP3).

METHODS

In the present study, we examined the effect of a highly selective angiotensin type 1 (AT-1) antagonist of angiotensin 2 receptor with high lipid solubility, telmisartan, on NVU and related inflammatory responses in SHR-SR with a low dose (0.3 mg/kg/day) only for improving metabolic syndrome, and a high dose (3 mg/kg/day) for improving both metabolic syndrome and SHR-SR hypertension.

RESULTS

Compared to normotensive Wistar rats, long-lasting hypertension in SHR-SR disrupted NVU by changing immunohistological components such as NAGO, collagen IV, astrocytes, and MMP-9. SHR-SR also strongly induced AD-related inflammasome NLRP3 in neuronal cells with age. However, such NVU disruption and inflammasome activation were greatly improved with dose-dependent telmisartan treatments.

DISCUSSION

These results suggest that telmisartan comprehensively protected the NVU components by reducing inflammatory reactions relative to AD in hypertensive rats, which could also preclude the risk of AD under hypertension.

The role of reactive oxygen species in microvascular remodeling

The microcirculation is a portion of the vascular circulatory system that consists of resistance arteries, arterioles, capillaries and venules. It is the place where gases and nutrients are exchanged between blood and tissues. In addition the microcirculation is the major contributor to blood flow resistance and consequently to regulation of blood pressure. Therefore, structural remodeling of this section of the vascular tree has profound implications on cardiovascular pathophysiology. This review is focused on the role that reactive oxygen species (ROS) play on changing the structural characteristics of vessels within the microcirculation. Particular attention is given to the resistance arteries and the functional pathways that are affected by ROS in these vessels and subsequently induce vascular remodeling. The primary sources of ROS in the microcirculation are identified and the effects of ROS on other microcirculatory remodeling phenomena such as rarefaction and collateralization are briefly reviewed.

Neurovascular protection by telmisartan via reducing neuroinflammation in stroke-resistant spontaneously hypertensive rat brain after ischemic stroke

Telmisartan is a highly lipid-soluble angiotensin receptor blocker (ARB), which improves insulin sensitivity and reduces triglyceride levels and, thus, is called metabo-sartan. We examined the effects of telmisartan on neurovascular unit (N-acetylglucosamine oligomer [NAGO], collagen IV, and glial fibrillary acidic protein [GFAP]) and neuroinflammation (matrix metalloproteinase-9 [MMP-9] and inflammasome) in brain of stroke-resistant spontaneously hypertensive rat (SHR-SR). At 12 weeks of age, SHR-SR received transient middle cerebral artery occlusion (tMCAO) for 90 minutes and were divided into the following 3 groups, that is, vehicle group, low-dose telmisartan group (.3 mg/kg/d), and high-dose telmisartan group (3 mg/kg/d, postoral). Immunohistologic analysis at ages 6, 12, and 18 months showed progressive decreases of NAGO-positive endothelium and collagen IV-positive basement membrane and progressive increases of MMP-9-positive neurons, GFAP-positive astrocytes, and NLRP3-positive inflammasome in the cerebral cortex of vehicle group. Low-dose telmisartan reduced such changes without lowering blood pressure (BP), and high-dose telmisartan further improved such changes with lowering BP. The present findings suggest that a persistent hypertension caused a long-lasting inflammation after tMCAO in SHR-SR, which accelerated neurovascular disruption and emergent inflammasome, and that telmisartan greatly reduced such inflammation and protected the neurovascular unit via its pleiotropic effects in living hypertensive rat brain after ischemic stroke.

Curcumin improves endothelial dysfunction and vascular remodeling in 2K-1C hypertensive rats by raising nitric oxide availability and reducing oxidative stress

Oxidative stress plays a role in maintaining high arterial blood pressure and contributes to the vascular changes that lead to hypertension. Consumption of polyphenol-rich foods has demonstrated their beneficial role in the prevention and treatment of hypertension. Curcumin (CUR), a phenolic compound present in the rhizomes of turmeric, possesses cardiovascular protective, anti-inflammatory and antioxidant properties. The present study was designed to investigate the protective effect of CUR on 2kidney-1clip (2K-1C)-induced hypertension, endothelial dysfunction, vascular remodeling and oxidative stress in male Sprague-Dawley rats. Sham operated or 2K-1C rats were treated with CUR at a dose of 50 or 100 mg/kg/day (or vehicle). After 6 weeks of treatment, CUR ameliorated hemodynamic performance in 2K-1C hypertensive rats (P< 0.05), by reducing blood pressure, increasing hindlimb blood flow and decreasing hindlimb vascular resistance. Hemodynamic restoration was associated with a reduction in plasma angiotensin converting enzyme level. Endothelium-dependent vasorelaxation, in response to acetylcholine, of aortic rings isolated from 2K-1C hypertensive rats-treated with CUR was significantly increased (P< 0.05). CUR also attenuated hypertension-induced oxidative stress and vascular structural modifications. These effects were associated with elevated plasma nitrate/nitrite, upregulated eNOS expression, downregulated p47phox NADPH oxidase and decreased superoxide production in the vascular tissues. The overall findings of this study suggest the mechanisms responsible for the antihypertensive action of CUR in 2K-1C hypertension-induced endothelial dysfunction and vascular remodeling involve the improvement NO bioavailability and a reduction in oxidative stress.

Smooth muscle cell deletion of low-density lipoprotein receptor-related protein 1 augments angiotensin II-induced superior mesenteric arterial and ascending aortic aneurysms

OBJECTIVE

Low-density lipoprotein receptor-related protein 1 (LRP1), a multifunctional protein involved in endocytosis and cell signaling pathways, leads to several vascular pathologies when deleted in vascular smooth muscle cells (SMCs). The purpose of this study was to determine whether LRP1 deletion in SMCs influenced angiotensin II-induced arterial pathologies.

APPROACH AND RESULTS

LRP1 protein abundance was equivalent in selected arterial regions, but SMC-specific LRP1 depletion had no effect on abdominal and ascending aortic diameters in young mice. To determine the effects of LRP1 deficiency on angiotensin II vascular responses, SMC-specific LRP1 (smLRP1(+/+)) and smLRP1-deficient (smLRP1(-/-)) mice were infused with saline, angiotensin II, or norepinephrine. Several smLRP(-/-) mice died of superior mesenteric arterial (SMA) rupture during angiotensin II infusion. In surviving mice, angiotensin II profoundly augmented SMA dilation in smLRP1(-/-) mice. SMA dilation was blood pressure dependent as demonstrated by a similar response during norepinephrine infusion. SMA dilation was also associated with profound macrophage accumulation, but minimal elastin fragmentation. Angiotensin II infusion led to no significant differences in abdominal aorta diameters between smLRP1(+/+) and smLRP1(-/-) mice. In contrast, ascending aortic dilation was exacerbated markedly in angiotensin II-infused smLRP1(-/-) mice, but norepinephrine had no significant effect on either aortic region. Ascending aortas of smLRP1(-/-) mice infused with angiotensin II had minimal macrophage accumulation but significantly increased elastin fragmentation and mRNA abundance of several LRP1 ligands including MMP-2 (matrix metalloproteinase-2) and uPA (urokinase plasminogen activator).

CONCLUSIONS

smLRP1 deficiency had no effect on angiotensin II-induced abdominal aortic aneurysm formation. Conversely, angiotensin II infusion in smLRP1(-/-) mice exacerbated SMA and ascending aorta dilation. Dilation in these 2 regions had differential association with blood pressure and divergent pathological characteristics.

The important role of catestatin in cardiac remodeling

Catestatin (CST) was first discovered as a potent non-competitive and reversible inhibitor of catecholamine secretion. Recent reports on plasma CST level in heart diseases suggested a cardioprotective role for this peptide. Given that cardiac remodeling is the dominant pathologic process in cardiac dysfunction, we propose that CST participates in the regulation of concern pathways and contributes to the inhibition of cardiac remodeling. In this minireview, the potential mechanism of cardiac remodeling involving CST will be discussed from three aspects: hypertrophy, fibrosis, and apoptosis.

Loss of NOX2 (gp91phox) prevents oxidative stress and progression to advanced heart failure

Oxidative stress plays a key pathogenic role in experimental and human heart failure. However, the source of ROS (reactive oxygen species) is a key determinant of the cardiac adaptation to pathological stressors. In the present study, we have shown that human dilated cardiomyopathy is associated with increased NOX2 (NADPH oxidase 2) levels, increased oxidative stress with adverse myocardial remodelling and activation of MAPKs (mitogen-activated protein kinases). Advanced heart failure in mice was also associated with increased NOX2 levels. Furthermore, we have utilized the pressure-overload model to examine the role of NOX2 in advanced heart failure. Increased cardiomyocyte hypertrophy and myocardial fibrosis in response to pressure overload correlated with increased oxidative stress, and loss of NOX2 prevented the increase in oxidative stress, development of cardiomyocyte hypertrophy, myocardial fibrosis and increased myocardial MMP (matrix metalloproteinase) activity in response to pressure overload. Consistent with these findings, expression of disease markers revealed a marked suppression of atrial natriuretic factor, β-myosin heavy chain, B-type natriuretic peptide and α-skeletal actin expression in pressure-overloaded hearts from NOX2-deficient mice. Activation of MAPK signalling, a well-known mediator of pathological remodelling, was lowered in hearts from NOX2-deficient mice in response to pressure overload. Functional assessment using transthoracic echocardiography and invasive pressure-volume loop analysis showed a marked protection in diastolic and systolic dysfunction in pressure-overloaded hearts from NOX2-deficient mice. Loss of NOX2 prevented oxidative stress in heart disease and resulted in sustained protection from the progression to advanced heart failure. Our results support a key pathogenic role of NOX2 in murine and human heart failure, and specific therapy antagonizing NOX2 activity may have therapeutic effects in advanced heart failure.

Identification of Hic-5 as a novel scaffold for the MKK4/p54 JNK pathway in the development of abdominal aortic aneurysms

BACKGROUND

Although increased amounts of reactive oxygen species in the pathogenesis of abdominal aortic aneurysm (AAA) are well documented, the precise molecular mechanisms by which reactive oxygen species induce AAAs have not been fully elucidated. This study focused on the role of hydrogen peroxide-inducible clone 5 (Hic-5), which is induced by hydrogen peroxide and transforming growth factor-β, in the cellular signaling of AAA pathogenesis.

METHODS AND RESULTS

Using the angiotensin II-induced AAA model in Apoe(-/-) mice, we showed that Apoe(-/-)Hic-5(-/-) mice were completely protected from AAA formation and aortic rupture, whereas Apoe(-/-) mice were not. These features were similarly observed in smooth muscle cell-specific Hic-5-deficient mice. Furthermore, angiotensin II treatment induced Hic-5 expression in a reactive oxygen species-dependent manner in aortic smooth muscle cells in the early stage of AAA development. Mechanistic studies revealed that Hic-5 interacted specifically with c-Jun N-terminal kinase p54 and its upstream regulatory molecule mitogen-activated protein kinase kinase 4 as a novel scaffold protein, resulting in the expression of membrane type 1 matrix metalloproteinase and matrix metalloproteinase 2 activation in aortic smooth muscle cells.

CONCLUSION

Hic-5 serves as a novel scaffold protein that specifically activates the mitogen-activated protein kinase kinase 4/p54 c-Jun N-terminal kinase pathway, thereby leading to the induction and activation of matrix metalloproteinases in smooth muscle cells and subsequent AAA formation. Our study provided a novel therapeutic option aimed at inhibiting the mitogen-activated protein kinase kinase 4-Hic-5-p54 c-Jun N-terminal kinase pathway in the vessel wall, particularly through Hic-5 inhibition, which may be used to produce more precise and effective therapies.

Caveolin 1 is critical for abdominal aortic aneurysm formation induced by angiotensin II and inhibition of lysyl oxidase

Although AngII (angiotensin II) and its receptor AT1R (AngII type 1 receptor) have been implicated in AAA (abdominal aortic aneurysm) formation, the proximal signalling events primarily responsible for AAA formation remain uncertain. Caveolae are cholesterol-rich membrane microdomains that serve as a signalling platform to facilitate the temporal and spatial localization of signal transduction events, including those stimulated by AngII. Cav1 (caveolin 1)-enriched caveolae in vascular smooth muscle cells mediate ADAM17 (a disintegrin and metalloproteinase 17)-dependent EGFR (epidermal growth factor receptor) transactivation, which is linked to vascular remodelling induced by AngII. In the present study, we have tested our hypothesis that Cav1 plays a critical role for the development of AAA at least in part via its specific alteration of AngII signalling within caveolae. Cav1-/- mice and the control wild-type mice were co-infused with AngII and β-aminopropionitrile to induce AAA. We found that Cav1-/- mice with the co-infusion did not develop AAA compared with control mice in spite of hypertension. We found an increased expression of ADAM17 and enhanced phosphorylation of EGFR in AAA. These events were markedly attenuated in Cav1-/- aortas with the co-infusion. Furthermore, aortas from Cav1-/- mice with the co-infusion showed less endoplasmic reticulum stress, oxidative stress and inflammatory responses compared with aortas from control mice. Cav1 silencing in cultured vascular smooth muscle cells prevented AngII-induced ADAM17 induction and activation. In conclusion, Cav1 appears to play a critical role in the formation of AAA and associated endoplasmic reticulum/oxidative stress, presumably through the regulation of caveolae compartmentalized signals induced by AngII.

Hemodynamic regulation of reactive oxygen species: implications for vascular diseases

SIGNIFICANCE

Arterial blood vessels functionally and structurally adapt to altering hemodynamic forces in order to accommodate changing needs and to provide stress homeostasis. This ability is achieved at the cellular level by converting mechanical stimulation into biochemical signals (i.e., mechanotransduction). Physiological mechanical stress helps maintain vascular structure and function, whereas pathologic or aberrant stress may impair cellular mechano-signaling, and initiate or augment cellular processes that drive disease.

RECENT ADVANCES

Reactive oxygen species (ROS) may represent an intriguing class of mechanically regulated second messengers. Chronically enhanced ROS generation may be induced by adverse mechanical stresses, and is associated with a multitude of vascular diseases. Although a causal relationship has clearly been demonstrated in large numbers of animal studies, an effective ROS-modulating therapy still remains to be established by clinical studies.

CRITICAL ISSUES AND FUTURE DIRECTIONS

This review article focuses on the role of various mechanical forces (in the form of laminar shear stress, oscillatory shear stress, or cyclic stretch) as modulators of ROS-driven signaling, and their subsequent effects on vascular biology and homeostasis, as well as on specific diseases such as arteriosclerosis, hypertension, and abdominal aortic aneurysms. Specifically, it highlights the significance of the various NADPH oxidase (NOX) isoforms as critical ROS generators in the vasculature. Directed targeting of defined components in the complex network of ROS (mechano-)signaling may represent a key for successful translation of experimental findings into clinical practice.

Effects of telmisartan on inflammatory cytokines and coronary plaque component as assessed on integrated backscatter intravascular ultrasound in hypertensive patients

BACKGROUND

Telmisartan has unique pleiotropic effects in addition to renin-angiotensin system (RAS)-inhibition effects. The aim of this study was to evaluate the effects of telmisartan on the coronary plaque component and local inflammatory cytokines.

METHODS AND RESULTS

A total of 50 patients with hypertension were randomized to 2 groups: the telmisartan group (additional treatment with telmisartan 80mg/day, n=25) or the control group (additional treatment with other anti-hypertensive drugs except RAS blockers, n=25) for 6 months. Tissue characteristics of target coronary plaque were analyzed using integrated backscatter intravascular ultrasound (IB-IVUS) before and after treatment. Plasma levels of inflammatory cytokines sampled in the coronary sinus (CS) and peripheral vein were also measured. Significant increases in fibrous volume (51.2±10.4 to 58.3±7.7%, P=0.03) and reductions in lipid volume (38.4±12.4 to 32.8±9.7%, P=0.03) were observed on IB in the telmisartan group, while there were no significant changes in the plaque component in the control group. CS levels of inflammatory cytokines (matrix metalloproteinase [MMP]3, tumor necrosis factor-α, high-sensitivity C-reactive protein and MMP9) were lower after than before treatment in the only telmisartan group (7.7±6.1 to 5.5±4.9ng/ml, 3.1±1.9 to 2.3±2.0pg/ml, 5.6±6.0 to 2.2±2.4mg/L, 36.1±39.3 to 19.9±27.5ng/ml, P=0.02, P=0.03, P=0.04, P=0.07, respectively).

CONCLUSIONS

Decreased local inflammatory response and plaque stabilization on IB imaging were observed after 6 months of telmisartan treatment. These findings might be associated with local anti-inflammatory and anti-arteriosclerotic effects of telmisartan.

Matrix metalloproteinases: inflammatory regulators of cell behaviors in vascular formation and remodeling

Abnormal angiogenesis and vascular remodeling contribute to pathogenesis of a number of disorders such as tumor, arthritis, atherosclerosis, restenosis, hypertension, and neurodegeneration. During angiogenesis and vascular remodeling, behaviors of stem/progenitor cells, endothelial cells (ECs), and vascular smooth muscle cells (VSMCs) and its interaction with extracellular matrix (ECM) play a critical role in the processes. Matrix metalloproteinases (MMPs), well-known inflammatory mediators are a family of zinc-dependent proteolytic enzymes that degrade various components of ECM and non-ECM molecules mediating tissue remodeling in both physiological and pathological processes. MMPs including MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-12, and MT1-MMP, are stimulated and activated by various stimuli in vascular tissues. Once activated, MMPs degrade ECM proteins or other related signal molecules to promote recruitment of stem/progenitor cells and facilitate migration and invasion of ECs and VSMCs. Moreover, vascular cell proliferation and apoptosis can also be regulated by MMPs via proteolytically cleaving and modulating bioactive molecules and relevant signaling pathways. Regarding the importance of vascular cells in abnormal angiogenesis and vascular remodeling, regulation of vascular cell behaviors through modulating expression and activation of MMPs shows therapeutic potential.

Temporal changes in cardiac matrix metalloproteinase activity, oxidative stress, and TGF-β in renovascular hypertension-induced cardiac hypertrophy

Cardiovascular remodeling found in later phases of two-kidney, one-clip (2K1C) hypertension may involve key mechanisms particularly including MMP-2, oxidative stress, transforming growth factor-β (TGF-β), and inactivation of the endogenous MMP inhibitor, the tissue inhibitor of MMP (TIMP)-4. We examined whether temporal cardiac remodeling resulting from 2K1C hypertension occurs concomitantly with alterations in cardiac collagen, MMP activity, MMP-2, TIMP-4, TGF-β, and reactive oxygen species (ROS) levels during the development of 2K1C hypertension. Sham-operated and 2K1C hypertensive rats were studied after 15, 30, and 75 days of hypertension. Systolic blood pressure was monitored weekly. Left ventricle (LV) morphometry and fibrosis were evaluated in hematoxylin/eosin and picrosirius red-stained sections, respectively. Cardiac MMP-2 levels/activity was determined by gelatin zymography, immunofluorescence, and in situ zymography. TIMP-4 levels were determined by western blotting. Cardiac TGF-β levels were evaluated by immunofluorescence and ROS levels were evaluated with a dihydroethidium probe. 2K1C hypertension induced LV hypertrophy associated with augmented gelatinolytic activity at an early phase of hypertension and further increased after 75 days of hypertension. These alterations were associated with increased cardiac MMP-2, TGF-β, and ROS in hypertensive rats. Higher TIMP-4 levels were found in hypertensive rats only after 75 days after surgery. Our findings show that increased MMP-2 activity is associated with concomitant development of LV hypertrophy and increased TGF-β and ROS levels.

Reactive oxygen species in vascular formation and development

Reactive oxygen species (ROS) are derived from the metabolism of oxygen and are traditionally viewed as toxic byproducts that cause damage to biomolecules. It is now becoming widely acknowledged that ROS are key modulators in a variety of biological processes and pathological states. ROS mediate key signaling transduction pathways by reversible oxidation of certain signaling components and are involved in the signaling of growth factors, G-protein-coupled receptors, Notch, and Wnt and its downstream cascades including MAPK, JAK-STAT, NF-κB, and PI3K/AKT. Vascular formation and development is one of the most important events during embryogenesis and is vital for postnasal tissue repair. In this paper, we will discuss how ROS regulate different steps in vascular development, including smooth muscle cell differentiation, angiogenesis, endothelial progenitor cells recruitment, and vascular cell migration.

HIV-1, reactive oxygen species, and vascular complications

Over 1 million people in the United States and 33 million individuals worldwide suffer from HIV/AIDS. Since its discovery, HIV/AIDS has been associated with an increased susceptibility to opportunistic infection due to immune dysfunction. Highly active antiretroviral therapies restore immune function and, as a result, people infected with HIV-1 are living longer. This improved survival of HIV-1 patients has revealed a previously unrecognized risk of developing vascular complications, such as atherosclerosis and pulmonary hypertension. The mechanisms underlying these HIV-associated vascular disorders are poorly understood. However, HIV-induced elevations in reactive oxygen species (ROS), including superoxide and hydrogen peroxide, may contribute to vascular disease development and progression by altering cell function and redox-sensitive signaling pathways. In this review, we summarize the clinical and experimental evidence demonstrating HIV- and HIV antiretroviral therapy-induced alterations in reactive oxygen species and how these effects are likely to contribute to vascular dysfunction and disease.

Contrasting effects of aliskiren versus losartan on hypertensive vascular remodeling

BACKGROUND

Hyperactivation of the renin-angiotensin system contributes to hypertension-induced upregulation of vascular matrix metalloproteinases (MMPs) and remodeling, especially in the two kidney, one clip (2K1C) hypertension model. We hypothesized that the AT1R antagonist losartan or the renin inhibitor aliskiren, given at doses allowing similar antihypertensive effects, could prevent in vivo vascular MMPs upregulation and remodeling, and collagen/elastin deposition found in 2K1C hypertension by preventing the activation of extracellular signal-regulated kinase 1/2 (ERK 1/2) and transforming growth factor-β1 (TGF-β1). We also hypothesized that aliskiren could enhance the effects of losartan.

METHODS

2K1C rats were treated with aliskiren (50mg.kg(-1).day(-1)), or losartan (10mg.kg(-1).day(-1)), or both by gavage during 4 weeks.

RESULTS

Aliskiren, losartan, or both drugs exerted similar antihypertensive effects when compared with 2K-1C rats treated with water. Aliskiren reduced plasma renin activity in both sham and 2K-1C rats. Losartan alone or combined with aliskiren, but not aliskiren alone, abolished 2K1C-induced aortic hypertrophy and hyperplasia, and prevented the increases in aortic collagen/elastin content, MMP-2 levels, gelatinolytic activity, and expression of phospho-ERK 1/2 and TGF-β1. No significant differences were found in the aortic expression of the (pro)renin receptor.

CONCLUSIONS

These findings show that although losartan and aliskiren exerted similar antihypertensive effects, only losartan prevented the activation of vascular profibrotic mechanisms and MMP upregulation associated with vascular remodeling in 2K1C hypertension. Our findings also suggest that aliskiren does not enhance the protective effects exerted by losartan.

Time course involvement of matrix metalloproteinases in the vascular alterations of renovascular hypertension

Increased vascular matrix metalloproteinases (MMPs) levels play a role in late phases of hypertensive vascular remodeling. However, no previous study has examined the time course of MMPs in the various phases of two-kidney, one-clip hypertension (2K1C). We examined structural vascular changes, collagen and elastin content, vascular oxidative stress, and MMPs levels/activities during the development of 2K1C hypertension. Plasma angiotensin converting enzyme (ACE) activity was measured to assess renin-angiotensin system activation. Sham or 2K1C hypertensive rats were studied after 2, 4, 6, and 10weeks of hypertension. Systolic blood pressure (SBP) was monitored weekly. Morphometry of structural changes in the aortic wall was studied in hematoxylin/eosin, orcein and picrosirius red sections. Aortic NADPH activity and superoxide production was evaluated. Aortic gelatinolytic activity was determined by in situ zymography, and MMP-2, MMP-14, and tissue inhibitor of MMPs (TIMP)-2 levels were determined by gelatin zymography, immunofluorescence and immunohistochemistry. 2K1C hypertension was associated with increased ACE activity, which decreased to normal after 10 weeks. We found increased aortic collagen and elastin content in the early phase of hypertension, which were associated with vascular hypertrophy, increased vascular MMP-2 and MMP-14 (but not TIMP-2) levels, and increased gelatinolytic activity, possibly as a result of increased vascular NADPH oxidase activity and oxidative stress. These results indicate that vascular remodeling of renovascular hypertension is an early process associated with early increases in MMPs activities, enhanced matrix deposition and oxidative stress. Using antioxidants or MMPs inhibitors in the early phase of hypertension may prevent the vascular alterations of hypertension.

AT1 receptor blockade delays postlactational mammary gland involution: a novel role for the renin angiotensin system

Angiotensin II (AngII), the main effector peptide of the renin-angiotensin system (RAS), participates in multiple biological processes, including cell growth, apoptosis, and tissue remodeling. Since AngII activates, in different cell types, signal transducing pathways that are critical for mammary gland postlactational regression, we investigated the role of the RAS during this process. We found that exogenous administration of AngII in mammary glands of lactating Balb/c mice induced epithelium apoptosis [2.9±0.5% (control) vs. 9.6±1.1% (AngII); P < 0.001] and activation of the proapoptotic factor STAT3, an effect inhibited by irbesartan, an AT(1) receptor blocker. Subsequently, we studied the expression kinetics of RAS components during involution. We found that angiotensin-converting enzyme (ACE) mRNA expression peaked 6 h after weaning (5.7-fold; P<0.01), while induction of angiotensinogen and AT(1) and AT(2) receptors expression was detected 96 h after weaning (6.2-, 10-, and 6.2-fold increase, respectively; P<0.01). To assess the role of endogenously generated AngII, mice were treated with losartan, an AT(1) receptor blocker, during mammary involution. Mammary glands from losartan-treated mice showed activation of the survival factors AKT and BCL-(XL), significantly lower LIF and TNF-α mRNA expression (P<0.05), reduced apoptosis [12.1±2.1% (control) vs. 4.8±0.7% (losartan); P<0.001] and shedding of epithelial cells, inhibition of MMP-9 activity in a dose-dependent manner (80%; P<0.05; with losartan IC(50) value of 6.9 mg/kg/d] and lower collagen deposition and adipocyte invasion causing a delayed involution compared to vehicle-treated mice. Furthermore, mammary glands of forced weaned AT(1A)- and/or AT(1B)-deficient mice exhibited retarded apoptosis of epithelial cells [6.3±0.95% (WT) vs. 3.3±0.56% (AT(1A)/AT(1B) DKO); P<0.05] with remarkable delayed postlactational regression compared to wild-type animals. Taken together, these results strongly suggest that AngII, via the AT(1) receptor, plays a major role in mouse mammary gland involution identifying a novel role for the RAS. angiotensin system.

p47(phox) is required for afferent arteriolar contractile responses to angiotensin II and perfusion pressure in mice

Myogenic and angiotensin contractions of afferent arterioles generate reactive oxygen species. Resistance vessels express neutrophil oxidase-2 and -4. Angiotensin II activates p47(phox)/neutrophil oxidase-2, whereas it downregulates NOX-4. Therefore, we tested the hypothesis that p47(phox) enhances afferent arteriolar angiotensin contractions. Angiotensin II infusion in p47(phox) +/+ but not -/- mice increased renal cortical NADPH oxidase activity (7±1-12±1 [P<0.01] versus 5±1-7±1 10(3) · RLU · min(-1) · μg protein(-1) [P value not significant]), mean arterial pressure (77±2-91±2 [P<0.005] versus 74±2-77±1 mm Hg [P value not significant]), and renal vascular resistance (7.5±0.4-10.1±0.7 [P<0.01] versus 7.9±0.4-8.3±0.4 mm Hg/mL · min(-1) · gram kidney weight(-1) [P value not significant]). Afferent arterioles from p47(phox) -/- mice had a lesser myogenic response (3.1±0.4 versus 1.4±0.2 dynes · cm(-1) · mm Hg(-1); P<0.02) and a lesser (P<0.05) contraction to 10(-6) M angiotensin II (diameter change +/+: 9.3±0.2-3.4±0.6 μm versus -/-: 9.9±0.6-7.5±0.4 μm). Angiotensin and increased perfusion pressure generated significantly (P<0.05) more reactive oxygen species in p47(phox) +/+ than -/- arterioles. Angiotensin II infusion increased the maximum responsiveness of afferent arterioles from p47(phox) +/+ mice to 10(-6) M angiotensin II yet decreased the response in p47(phox) -/- mice. The angiotensin infusion increased the sensitivity to angiotensin II only in p47(phox) +/+ mice. We conclude that p47(phox) is required to enhance renal NADPH oxidase activity and basal afferent arteriolar myogenic and angiotensin II contractions and to switch afferent arteriolar tachyphylaxis to sensitization to angiotensin during a prolonged angiotensin infusion. These effects likely contribute to hypertension and renal vasoconstriction during infusion of angiotensin II.

Human matrix metalloproteinases: an ubiquitarian class of enzymes involved in several pathological processes

Human matrix metalloproteinases (MMPs) belong to the M10 family of the MA clan of endopeptidases. They are ubiquitarian enzymes, structurally characterized by an active site where a Zn(2+) atom, coordinated by three histidines, plays the catalytic role, assisted by a glutamic acid as a general base. Various MMPs display different domain composition, which is very important for macromolecular substrates recognition. Substrate specificity is very different among MMPs, being often associated to their cellular compartmentalization and/or cellular type where they are expressed. An extensive review of the different MMPs structural and functional features is integrated with their pathological role in several types of diseases, spanning from cancer to cardiovascular diseases and to neurodegeneration. It emerges a very complex and crucial role played by these enzymes in many physiological and pathological processes.

Adiponectin mediates cardioprotection in oxidative stress-induced cardiac myocyte remodeling

Reactive oxygen species (ROS) induce matrix metalloproteinase (MMP) activity that mediates hypertrophy and cardiac remodeling. Adiponectin (APN), an adipokine, modulates cardiac hypertrophy, but it is unknown if APN inhibits ROS-induced cardiomyocyte remodeling. We tested the hypothesis that APN ameliorates ROS-induced cardiomyocyte remodeling and investigated the mechanisms involved. Cultured adult rat ventricular myocytes (ARVM) were pretreated with recombinant APN (30 μg/ml, 18 h) followed by exposure to physiologic concentrations of H(2)O(2) (1-200 μM). ARVM hypertrophy was measured by [(3)H]leucine incorporation and atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) gene expression by RT-PCR. MMP activity was assessed by in-gel zymography. ROS was induced with angiotensin (ANG)-II (3.2 mg·kg(-1)·day(-1) for 14 days) in wild-type (WT) and APN-deficient (APN-KO) mice. Myocardial MMPs, tissue inhibitors of MMPs (TIMPs), p-AMPK, and p-ERK protein expression were determined. APN significantly decreased H(2)O(2)-induced cardiomyocyte hypertrophy by decreasing total protein, protein synthesis, ANF, and BNP expression. H(2)O(2)-induced MMP-9 and MMP-2 activities were also significantly diminished by APN. APN significantly increased p-AMPK in both nonstimulated and H(2)O(2)-treated ARVM. H(2)O(2)-induced p-ERK activity and NF-κB activity were both abrogated by APN pretreatment. ANG II significantly decreased myocardial p-AMPK and increased p-ERK expression in vivo in APN-KO vs. WT mice. ANG II infusion enhanced cardiac fibrosis and MMP-2-to-TIMP-2 and MMP-9-to-TIMP-1 ratios in APN-KO vs. WT mice. Thus APN inhibits ROS-induced cardiomyocyte remodeling by activating AMPK and inhibiting ERK signaling and NF-κB activity. Its effects on ROS and ultimately on MMP expression define the protective role of APN against ROS-induced cardiac remodeling.