C-atrial natriuretic peptide (ANP)4-23 attenuates renal fibrosis in deoxycorticosterone-acetate-salt hypertensive mice

Epithelial-mesenchymal transition (EMT) plays a critical role in hypertension-induced renal fibrosis, a final pathway that leads to end-stage renal failure. C-Atrial natriuretic peptide (ANP)4-23, a specific agonist of natriuretic peptide receptor-C (NPR-C), has been reported to have protective effects against hypertension. However, the role of C-ANP4-23 in hypertension-associated renal fibrosis has not yet been elucidated. In this study, mice were randomly divided into SHAM group, DOCA-salt group and DOCA-salt + C-ANP4-23 group. Renal morphology changes, renal function and fibrosis were detected. Human proximal tubular epithelial cells (HK2) stimulated by aldosterone were used for cell function and mechanism study. The DOCA-salt treated mice exhibited hypertension, kidney fibrosis and renal dysfunction, which were attenuated by C-ANP4-23. Moreover, C-ANP4-23 inhibited DOCA-salt treatment-induced renal EMT as evidenced by decrease of the mesenchymal marker alpha-smooth muscle actin (ACTA2) and vimentin and increase of epithelial cell marker E-cadherin. In HK2 cells, aldosterone induced EMT response, which was also suppressed by C-ANP4-23. The key transcription factors (twist, snail, slug and ZEB1) involved in EMT were increased in the kidney of DOCA-salt-treated mice, which were also suppressed by C-ANP4-23. Mechanistically, C-ANP4-23 inhibited the aldosterone-induced translocation of MR from cytosol to nucleus without change of MR expression. Furthermore, C-ANP4-23 rescued the enhanced expression of NADPH oxidase (NOX) 4 and oxidative stress after aldosterone stimulation. Aldosterone-induced Akt and Erk1/2 activation was also suppressed by C-ANP4-23. Our data suggest that C-ANP4-23 attenuates renal fibrosis, likely through inhibition of MR activation, enhanced oxidative stress and Akt and Erk1/2 signaling pathway.

An IL-6/STAT3/MR/FGF21 axis mediates heart-liver cross-talk after myocardial infarction

The liver plays a protective role in myocardial infarction (MI). However, very little is known about the mechanisms. Here, we identify mineralocorticoid receptor (MR) as a pivotal nexus that conveys communications between the liver and the heart during MI. Hepatocyte MR deficiency and MR antagonist spironolactone both improve cardiac repair after MI through regulation on hepatic fibroblast growth factor 21 (FGF21), illustrating an MR/FGF21 axis that underlies the liver-to-heart protection against MI. In addition, an upstreaming acute interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) pathway transmits the heart-to-liver signal to suppress MR expression after MI. Hepatocyte Il6 receptor deficiency and Stat3 deficiency both aggravate cardiac injury through their regulation on the MR/FGF21 axis. Therefore, we have unveiled an IL-6/STAT3/MR/FGF21 signaling axis that mediates heart-liver cross-talk during MI. Targeting the signaling axis and the cross-talk could provide new strategies to treat MI and heart failure.

Prevalence and clinical characteristics of renovascular hypertension associated with fibromuscular dysplasia in China

OBJECTIVES

The aim of this study was to investigate the clinical characteristics of renal artery fibromuscular dysplasia (FMD) in patients in China and identify the cure rate of hypertension after angioplasty.

METHODS

Consecutive hypertensive patients with renal artery stenosis caused by FMD who underwent catheter-based angiography, and were followed at two Chinese referral centres, were retrospectively analysed. All patients underwent a detailed investigation, including demographic characteristics, clinical characteristics, biochemical sampling, Doppler ultrasonography of carotid arteries, magnetic resonance angiography (MRA) of the intracranial artery, and CTA or MRA of the abdominal artery and catheter-based renal angiography. Patients were routinely followed up at 1 month, 6 months and every year after the procedure.

RESULTS

Among 245 study participants, with a mean diagnosed age of 26.9 ± 9.9 years, 137 (55.9%) were women, and 38 (15.5%) were children. All patients were diagnosed with hypertension at a mean age of 23.4 ± 8.4 years. There were 73.5% focal and 15.2% multivessel cases. Aneurysms, arterial dissections and total occlusions were found in 21.6, 4.1 and 12.2% of patients, respectively. Patients with multifocal FMD were older (26.0 vs. 23.7 years, P  = 0.021) and more often female (70.8 vs. 50.6%, P  = 0.004). Among children with renal FMD, 55.2% were men, and 86.8% were focal. After a median follow-up of 7.0 years, multifocal FMD had a higher cure rate of hypertension than focal FMD after revascularization (71.7 vs. 55.8%, P  = 0.032).

CONCLUSION

In a cohort of mostly young Chinese patients, the prevalence of hypertension associated with renal FMD is similar in both sexes. Focal FMDs were more frequent than the multifocal ones and, after angioplasty, were associated with a worse blood pressure outcome.

Loss of C3a and C5a receptors promotes adipocyte browning and attenuates diet-induced obesity via activating inosine/A2aR pathway

Complement activation is thought to underline the pathologic progression of obesity-related metabolic disorders; however, its role in adaptive thermogenesis has scarcely been explored. Here, we identify complement C3a receptor (C3aR) and C5a receptor (C5aR) as critical switches to control adipocyte browning and energy balance in male mice. Loss of C3aR and C5aR in combination, more than individually, increases cold-induced adipocyte browning and attenuates diet-induced obesity in male mice. Mechanistically, loss of C3aR and C5aR increases regulatory T cell (Treg) accumulation in the subcutaneous white adipose tissue during cold exposure or high-fat diet. Activated Tregs produce adenosine, which is converted to inosine by adipocyte-derived adenosine deaminases. Inosine promotes adipocyte browning in a manner dependent on activating adenosine A2a receptor. These data reveal a regulatory mechanism of complement in controlling adaptive thermogenesis and suggest that targeting the C3aR/C5aR pathways may represent a therapeutic strategy in treating obesity-related metabolic diseases.

Mitogen-Activated Protein Kinases Mediate Adventitial Fibroblast Activation and Neointima Formation via GATA4/Cyclin D1 Axis

PURPOSE

Activation of mitogen-activated protein kinases (MAPKs) by pathological stimuli participates in cardiovascular diseases. Dysfunction of adventitial fibroblast has emerged as a critical regulator in vascular remodeling, while the potential mechanism remains unclear. In this study, we sought to determine the effect of different activation of MAPKs in adventitial fibroblast contributing to neointima formation.

METHODS

Balloon injury procedure was performed in male 12-week-old Sprague-Dawley rats. After injury, MAPK inhibitors were applied to the adventitia of injured arteries to suppress MAPK activation. Adventitial fibroblasts were stimulated by platelet-derived growth factor-BB (PDGF-BB) with or without MAPK inhibitors. RNA sequencing was performed to investigate the change of pathway and cell function. Wound healing, transwell assay, and flow cytometry were used to analyze adventitial fibroblast function.

RESULTS

Phosphorylation of p38, c-Jun N-terminal kinase (JNK), and extracellular regulated kinases 1/2 (ERK1/2) was increased in injured arteries after balloon injury. In primary culture of adventitial fibroblasts, PDGF-BB increased phosphorylation of p38, JNK, ERK1/2, and extracellular regulated kinase 5 (ERK5) in a short time, which was normalized by their inhibitors respectively. Compared with the injury group, perivascular administration of four MAPK inhibitors significantly attenuated neointima formation by quantitative analysis of neointimal area, intima to media (I/M) ratio, and lumen area. RNA sequencing of adventitial fibroblasts treated with PDGF-BB with or without four inhibitors demonstrated differentially expressed genes involved in multiple biological processes, including cell adhesion, proliferation, migration, and inflammatory response. Wound healing and transwell assays showed that four inhibitors suppressed PDGF-BB-induced adventitial fibroblast migration. Cell cycle analysis by flow cytometry demonstrated that JNK, ERK1/2, and ERK5 but not p38 inhibitor blocked PDGF-BB-induced G1 phase release associated with decrease expression of cell cycle protein Cyclin D1 and transcription factor GATA4. Moreover, four inhibitors decreased macrophage infiltration into adventitia and monocyte chemoattractant protein-1 (MCP-1) expression.

CONCLUSION

These results suggest that MAPKs differentially regulate activation of adventitial fibroblast through GATA4/Cyclin D1 axis that participates in neointima formation.

Brown Adipocyte ADRB3 Mediates Cardioprotection via Suppressing Exosomal iNOS

BACKGROUND

The ADRB3 (β3-adrenergic receptors), which is predominantly expressed in brown adipose tissue (BAT), can activate BAT and improve metabolic health. Previous studies indicate that the endocrine function of BAT is associated with cardiac homeostasis and diseases. Here, we investigate the role of ADRB3 activation-mediated BAT function in cardiac remodeling.

METHODS

BKO (brown adipocyte-specific ADRB3 knockout) and littermate control mice were subjected to Ang II (angiotensin II) for 28 days. Exosomes from ADRB3 antagonist SR59230A (SR-exo) or agonist mirabegron (MR-exo) treated brown adipocytes were intravenously injected to Ang II-infused mice.

RESULTS

BKO markedly accelerated cardiac hypertrophy and fibrosis compared with control mice after Ang II infusion. In vitro, ADRB3 KO rather than control brown adipocytes aggravated expression of fibrotic genes in cardiac fibroblasts, and this difference was not detected after exosome inhibitor treatment. Consistently, BKO brown adipocyte-derived exosomes accelerated Ang II-induced cardiac fibroblast dysfunction compared with control exosomes. Furthermore, SR-exo significantly aggravated Ang II-induced cardiac remodeling, whereas MR-exo attenuated cardiac dysfunction. Mechanistically, ADRB3 KO or SR59230A treatment in brown adipocytes resulted an increase of iNOS (inducible nitric oxide synthase) in exosomes. Knockdown of iNOS in brown adipocytes reversed SR-exo-aggravated cardiac remodeling.

CONCLUSIONS

Our data illustrated a new endocrine pattern of BAT in regulating cardiac remodeling, suggesting that activation of ADRB3 in brown adipocytes offers cardiac protection through suppressing exosomal iNOS.

Lung mesenchymal stromal cells influenced by Th2 cytokines mobilize neutrophils and facilitate metastasis by producing complement C3

Pre-metastatic niche formation is critical for the colonization of disseminated cancer cells in distant organs. Here we find that lung mesenchymal stromal cells (LMSCs) at pre-metastatic stage possess potent metastasis-promoting activity. RNA-seq reveals an upregulation of complement 3 (C3) in those LMSCs. C3 is found to promote neutrophil recruitment and the formation of neutrophil extracellular traps (NETs), which facilitate cancer cell metastasis to the lungs. C3 expression in LMSCs is induced and sustained by Th2 cytokines in a STAT6-dependent manner. LMSCs-driven lung metastasis is abolished in Th1-skewing Stat6-deficient mice. Blockade of IL-4 by antibody also attenuates LMSCs-driven cancer metastasis to the lungs. Consistently, metastasis is greatly enhanced in Th2-skewing T-bet-deficient mice or in nude mice adoptively transferred with T-bet-deficient T cells. Increased C3 levels are also detected in breast cancer patients. Our results suggest that targeting the Th2-STAT6-C3-NETs cascade may reduce breast cancer metastasis to the lungs.

The formation of the pre-metastatic niche enables the colonisation of disseminated cancer cells in distant organs. Here, the authors show that Th2 cytokines induce Complement 3 production in lung mesenchymal stromal cells, which recruits neutrophils and promotes the formation neutrophil extracellular traps, facilitating breast cancer cell metastasis to the lungs.

PDGF-D activation by macrophage-derived uPA promotes AngII-induced cardiac remodeling in obese mice

Obesity-induced secretory disorder of adipose tissue-derived factors is important for cardiac damage. However, whether platelet-derived growth factor-D (PDGF-D), a newly identified adipokine, regulates cardiac remodeling in angiotensin II (AngII)-infused obese mice is unclear. Here, we found obesity induced PDGF-D expression in adipose tissue as well as more severe cardiac remodeling compared with control lean mice after AngII infusion. Adipocyte-specific PDGF-D knockout attenuated hypertensive cardiac remodeling in obese mice. Consistently, adipocyte-specific PDGF-D overexpression transgenic mice (PA-Tg) showed exacerbated cardiac remodeling after AngII infusion without high-fat diet treatment. Mechanistic studies indicated that AngII-stimulated macrophages produce urokinase plasminogen activator (uPA) that activates PDGF-D by splicing full-length PDGF-D into the active PDGF-DD. Moreover, bone marrow-specific uPA knockdown decreased active PDGF-DD levels in the heart and improved cardiac remodeling in HFD hypertensive mice. Together, our data provide for the first time a new interaction pattern between macrophage and adipocyte: that macrophage-derived uPA activates adipocyte-secreted PDGF-D, which finally accelerates AngII-induced cardiac remodeling in obese mice.

Cardiac Fibroblast-Specific Knockout of PGC-1α Accelerates AngII-Induced Cardiac Remodeling

Cardiac remodeling consisted of ventricular hypertrophy and interstitial fibrosis is the pathological process of many heart diseases. Fibroblasts as one of the major cells in the myocardium regulate the balance of the generation and degeneration of collagen, and these cells transform toward myofibroblasts in pathological state, contributing to the remodeling of the heart. Peroxisome proliferator-activated receptor-γ (PPAR-γ) coactivator-1α (PGC-1α) is vital to the function of mitochondria, which contributes to the energy production and reactive oxidative species (ROS)-scavenging activity in the heart. In this study, we found that fibroblast-specific PGC-1α KO induced cardiac remodeling especially fibrosis, and Angiotensin II (AngII) aggravated cardiac fibrosis, accompanied with a high level of oxidative stress response and inflammation.

Senescent T Cell Induces Brown Adipose Tissue "Whitening" Via Secreting IFN-γ

Aging-associated chronic inflammation is a key contributing factor to a cluster of chronic metabolic disorders, such as cardiovascular disease, obesity, and type 2 diabetes. Immune cells particularly T cells accumulate in adipose tissue with advancing age, and there exists a cross talk between T cell and preadipocyte, contributing to age-related adipose tissue remodeling. Here, we compared the difference in morphology and function of adipose tissue between young (3-month-old) and old (18-month-old) mice and showed the phenomenon of brown adipose tissue (BAT) “whitening” in old mice. Flow cytometry analysis suggested an increased proportion of T cells in BAT of old mice comparing with the young and exhibited senescent characteristics. We take advantage of coculture system to demonstrate directly that senescent T cells inhibited brown adipocyte differentiation of preadipocytes in adipose tissue. Mechanistically, both in vitro and in vivo studies suggested that senescent T cells produced and released a higher level of IFN-γ, which plays a critical role in inhibition of preadipocyte-to-brown adipocyte differentiation. Taken together, the data indicate that senescent T cell-derived IFN-γ is a key regulator in brown adipocyte differentiation.

Renal Natriuretic Peptide Receptor-C Deficiency Attenuates NaCl Cotransporter Activity in Angiotensin II-Induced Hypertension

Genome-wide association studies have identified that NPR-C (natriuretic peptide receptor-C) variants are associated with elevation of blood pressure. However, the mechanism underlying the relationship between NPR-C and blood pressure regulation remains elusive. Here, we investigate whether NPR-C regulates Ang II (angiotensin II)-induced hypertension through sodium transporters activity. Wild-type mice responded to continuous Ang II infusion with an increased renal NPR-C expression. Global NPR-C deficiency attenuated Ang II-induced increased blood pressure both in male and female mice associated with more diuretic and natriuretic responses to a saline challenge. Interestingly, Ang II increased both total and phosphorylation of NCC (NaCl cotransporter) abundance involving in activation of WNK4 (with-no-lysine kinase 4)/SPAK (Ste20-related proline/alanine-rich kinase) which was blunted by NPR-C deletion. NCC inhibitor, hydrochlorothiazide, failed to induce natriuresis in NPR-C knockout mice. Moreover, low-salt and high-salt diets-induced changes of total and phosphorylation of NCC expression were normalized by NPR-C deletion. Importantly, tubule-specific deletion of NPR-C also attenuated Ang II-induced elevated blood pressure, total and phosphorylation of NCC expression. Mechanistically, in distal convoluted tubule cells, Ang II dose and time-dependently upregulated WNK4/SPAK/NCC kinase pathway and NPR-C/Gi/PLC/PKC signaling pathway mediated NCC activation. These results demonstrate that NPR-C signaling regulates NCC function contributing to sodium retention-mediated elevated blood pressure, which suggests that NPR-C is a promising candidate for the treatment of sodium retention-related hypertension.

T-cell senescence accelerates angiotensin II-induced target organ damage

AIMS

Aging is a risk factor for cardiovascular diseases and adaptive immunity has been implicated in angiotensin (Ang) II-induced target organ dysfunction. Herein, we sought to determine the role of T-cell senescence in Ang II-induced target organ impairment and to explore the underlying mechanisms.

METHODS AND RESULTS

Flow cytometric analysis revealed that T cell derived from aged mice exhibited immunosenescence. Adoptive transfer of aged T cells to immunodeficient RAG1 KO mice accelerates Ang II-induced cardiovascular and renal fibrosis compared with young T-cell transfer. Aged T cells also promote inflammatory factor expression and superoxide production in these target organs. In vivo and in vitro studies revealed that Ang II promotes interferon-gamma (IFN-γ) production in the aged T cells comparing to young T cells. Importantly, transfer of senescent T cell that IFN-γ KO mitigates the impairment. Aged T-cell-conditioned medium stimulates inflammatory factor expression and oxidative stress in Ang II-treated renal epithelial cells compared with young T cells, and these effects of aged T-cell-conditioned medium are blunted after IFN-γ-neutralizing antibody pre-treatment.

CONCLUSION

These results provide a significant insight into the contribution of senescent T cells to Ang II-induced cardiovascular dysfunction and provide an attractive possibility that targeting T cell specifically might be a potential strategy to treat elderly hypertensive patients with end-organ dysfunction.

The Role of Brown Adipose Tissue Dysfunction in the Development of Cardiovascular Disease

Brown adipose tissue (BAT), consisted of brown adipocytes and stromal vascular fraction, which includes endothelial cells, lymphocytes, fibroblasts and stem cells, plays a vital role in regulating cardiovascular health and diseases. As a thermogenic organ, BAT can influence body through strengthening energy expenditure by promoting glucose and lipid metabolism. In addition, BAT is also an endocrine organ which is able to secret adipokines in an autocrine and/or paracrine fashion. BAT plays a protective role in cardiovascular system through attenuating cardiac remodeling and suppressing inflammatory response. In this review, we summarize the advances from the discovery of BAT to the present and provide an overview on the role of BAT dysfunction in cardiovascular diseases.

Recurrence of Primary Aldosteronism 10 Years After Left Adrenalectomy for Aldosterone-Producing Adenoma: A Case Report

A 29-year-old female patient diagnosed with primary aldosteronism (PA) in 2004 underwent complete adrenalectomy for left aldosterone-producing adenoma (APA) confirmed by hematoxylin and eosin (HE) and CYP11B2 staining. Her hypokalemia was corrected, and her blood pressure (BP) normalized and maintained without medication for 10 years. In 2014, her BP became elevated again, and a recurrence of PA with an adenoma on the right adrenal gland was discovered by computed tomography scan. She underwent partial right adrenalectomy in 2018 due to unsatisfactory BP control with medication and gradually enlarging adenoma. The resected adrenal tissue contained a CYP11B2 staining positive APA. Her BP was then controlled by two drugs. Sanger sequencing of DNA extracted from tissue slices revealed that both left and right adenomas carried the same aldosterone-driver KCNJ5 gene mutation, but with different nucleotide changes. We suggest that patients who undergo adrenalectomy for APA should be followed up for life.

HIF-1α-BNIP3-mediated mitophagy in tubular cells protects against renal ischemia/reperfusion injury

In the present study, we hypothesized that hypoxia-inducible factor 1α (HIF-1α)-mediated mitophagy plays a protective role in ischemia/reperfusion (I/R)-induced acute kidney injury (AKI). Mitophagy was evaluated by measuring the changes of mitophagy flux, mitochondria DNA copy number, and the changes of mitophagy-related proteins including translocase of outer mitochondrial membrane 20 (TOMM20), cytochrome c oxidase IV (COX IV), microtubule-associated protein 1 light chain 3B (LC3B), and mitochondria adaptor nucleoporin p62 in HK2 cells, a human tubular cell line. Results show that HIF-1α knockout significantly attenuated hypoxia/reoxygenation (H/R)-induced mitophagy, aggravated H/R-induced apoptosis, and increased the production of reactive oxygen species (ROS). Similarly, H/R induced significantly increase in Bcl-2 19-kDa interacting protein 3 (BNIP3), a downstream regulator of HIF-1α. Notably, BNIP3 overexpression reversed the inhibitory effect of HIF-1α knockout on H/R-induced mitophagy, and prevented the enhancing effect of HIF-1α knockout on H/R-induced apoptosis and ROS production. For in vivo study, we established HIF-1αflox/flox; cadherin-16-cre mice in which tubular HIF-1α was specifically knockout. It was found that tubular HIF-1α knockout significantly inhibited I/R-induced mitophagy, and aggravated I/R-induced tubular apoptosis and kidney damage. In contrast, adenovirus-mediated BNIP3 overexpression significantly reversed the decreased mitophagy, and prevented enhanced kidney damage in tubular HIF-1α knockout mice with I/R injury. In summary, our study demonstrated that HIF-1α-BNIP3-mediated mitophagy in tubular cells plays a protective role through inhibition of apoptosis and ROS production in acute kidney damage.

Involvement of Angiotensin II Type 1 Receptor and Calcium Channel in Vascular Remodeling and Endothelial Dysfunction in Rats with Pressure Overload

Vascular remodeling is an adaptive response to various stimuli, including mechanical forces, inflammatory cytokines and hormones. In the present study, we investigated the role of angiotensin II type 1 receptor (AT1R) and calcium channel in carotid artery remodeling in response to increased biomechanical forces by using the transverse aortic constriction (TAC) rat model. TAC was induced on ten-week-old male Sprague-Dawley rats and these models were treated with AT1R blocker olmesartan (1 mg/kg/day) or/and calcium channel blocker (CCB) amlodipine (0.5 mg/kg/day) for 14 days. After the treatment, the right common carotid artery proximal to the band (RCCA-B) was collected for further assay. Results showed that olmesartan, but not amlodipine, significantly prevented TAC-induced adventitial hyperplasia. Similarly, olmesartan, but not amlodipine, signifcantly prevented vascular infammation, as indicated by increased tumor necrosis factor α (TNF-α) and increased p65 phosphorylation, an indicator of nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) activation in RCCA-B. In contrast, both olmesartan and amlodipine reversed the decreased expression of endothelial nitric oxidase synthase (eNOS) and improved endothelium-dependent vasodilation, whereas combination of olmesartan and amlodipine showed no further synergistic protective effects. These results suggest that AT1R was involved in vascular remodeling and inflammation in response to pressure overload, whereas AT1R and subsequent calcium channel were involved in endothelial dysfunction.

Adenosine A2A receptor activation prevents DOCA-salt induced hypertensive cardiac remodeling via iBAT

Hypertensive cardiac remodeling is a constellation of abnormalities that includes cardiomyocyte hypertrophy and death and tissue fibrosis. Adenosine is a long-known vasodilator, through interacting with its four cell surface receptor subtypes in cardiovascular system. However, it is unclear that whether adenosine A2A receptor (A2AR) activation is involved in the cardiac remodeling in hypertension. WT mice were utilized to induce DOCA-salt sensitive hypertension and received A2AR agonist CGS21680 or antagonist KW6002 treatment. Cardiac functional phenotyping measurement by echocardiography showed that CGS21680 improved cardiac dysfunction in DOCA-salt mice. Moreover, CGS21680 reduced cardiomyocyte hypertrophy, cardiac inflammation and fibrosis. However, iBAT depletion surgery induces dramatic cardiac remodeling in DOCA-salt mice, and the protective function of CGS21680 was blocked without intact iBAT. Mechanistically, A2AR agonist CGS21680 increased iBAT-derived fibroblast growth factor 21 (FGF21). Our data suggest that activation of A2AR could be a potential therapeutic strategy in preventing heart damage in hypertension.

Adventitial fibroblast-derived vascular endothelial growth factor promotes vasa vasorum-associated neointima formation and macrophage recruitment

Aims

Adventitial vasa vasorum provides oxygen and nourishment to the vascular wall, but whether it regulates vascular disease remains unclear. We have previously shown that an increased expression of VEGF (vascular endothelial growth factor) is associated with macrophage infiltration. This study aims to determine whether adventitial fibroblast (AF)-derived VEGF increases the number of vasa vasorum contributing to neointima formation through macrophage recruitment.

Methods and results

In rat balloon injury model, vasa vasorum count was increased particularly in the adventitia accompanied by cell proliferation and VEGF expression. Both endogenous and PKH26-labelled exogenous macrophages were mainly distributed in adventitia around vasa vasorum. Interestingly, perivascular delivery of Ranibizumab preferentially concentrated in adventitia resulted in a decrease of neointima formation with concurrent reduction of vasa vasorum count and macrophage infiltration. AFs with adenovirus-mediated VEGF over-expression delivered to the adventitia significantly enhanced these pathological changes after injury. In Tie2-cre/Rosa-LoxP-RFP mice, endothelial cells were increased in the adventitia after wire injury. By using multiphoton laser scanning microscopy, macrophage rolling, adhesion and transmigration were observed in vasa vasorum. Moreover, adoptive transfer of macrophages accelerated injury-induced neointima formation. VEGF-neutralizing antibody administration also attenuated wire injury-induced neointima formation and macrophage infiltration. In primary cultured AFs, exogenous VEGF increased VEGF expression and secretion in a time- and dose-dependent manner. AF-conditioned medium promoted endothelial cell angiogenesis, vascular cell adhesion molecule-1 expression and macrophage adhesion was blocked by VEGF-neutralizing antibody and VEGFR2 inhibitor ZM323881, which also inhibited activation of VEGFR2/ERK1/2 pathway.

Conclusion

These results demonstrate that AF-derived VEGF plays a significant role in the increase of vasa vasorum count which is involved in macrophage recruitment and neointima formation.

Loss of miR-146b-3p Inhibits Perivascular Adipocyte Browning with Cold Exposure During Aging

PURPOSE

Pathological changes of the perivascular adipose tissue (PVAT) are directly associated with increased risk of age-related vascular diseases. MicroRNAs regulate adipocyte biological functions including adipogenic differentiation and white adipocyte browning. The present study aims to determine whether miR-146b-3p is involved in the regulation of perivascular adipocyte browning during aging.

METHODS

We utilized a cold-induced animal model to investigate the effect of aging on perivascular adipocyte browning. We also detected the miR-146b-3p expression in the PVAT of young or old mice after cold stimulus. We further investigated the role of miR-146b-3p in regulating perivascular adipocyte browning in vitro and in vivo via administrating miRNA mimics or inhibitors.

RESULTS

Old mice showed decrease of perivascular adipocyte browning and downregulation of miR-146b-3p expression in the PVAT after cold stimulus. Oil red O staining and qPCR indicated that aging perturbed preadipocyte to brown adipocyte differentiation, and expression of miR-146b-3p gradually increased during differentiation. MiR-146b-3p inhibitors blocked brown adipocyte differentiation in young preadipocytes, whereas miR-146b-3p mimics rescued the differentiation of the old preadipocytes. Finally, miR-146b-3p knocks down inhibited perivascular adipocyte browning in young mice after cold stimulus.

CONCLUSION

Aging inhibits perivascular adipocyte browning, and loss of miR-146b-3p is a potential regulator for this process.

Membrane raft redox signalling contributes to endothelial dysfunction and vascular remodelling of thoracic aorta in angiotensin II-infused rats

NEW FINDINGS

What is the central question of this study? Is the membrane raft redox signalling pathway involved in blood pressure increase, endothelial dysfunction and vascular remodelling in an angiotensin II-induced hypertensive animal model? What is the main finding and its importance? The membrane raft redox signalling pathway was involved in endothelial dysfunction and medial remodelling in angiotensin II-induced hypertension.

ABSTRACT

The membrane raft (MR) redox pathway is characterized by NADPH oxidase activation via the clustering of its subunits through lysosome fusion and the activation of acid sphingomyelinase (ASMase). Our previous study shows that the MR redox signalling pathway is associated with angiontensin II (AngII)-induced production of reactive oxygen species (ROS) and endothelial dysfunction in rat mesenteric arteries. In the present study, we hypothesized that this signalling pathway is involved in blood pressure increase, endothelial dysfunction and vascular remodelling in an AngII-induced hypertensive animal model. Sixteen-week-old male Sprague-Dawley rats were subjected to AngII infusion for 2 weeks with or without treatment with the lysosome fusion inhibitor bafilomycin A1 and ASMase inhibitor amitriptyline. After treatments, aortas were harvested for further study. The results showed that the MR redox signalling pathway was activated as indicated by the increase of MR formation, ASMase activity and ROS production in aorta from AngII-infused rats compared with that from control rats. MR formation and ROS production were significantly inhibited in thoracic aorta from AngII-induced rats treated with bafilomycin A1 and amitriptyline. Both treatments significantly attenuated blood pressure increase, endothelial dysfunction and vascular remodelling including medial hypertrophy, and increased collagen and fibronectin deposition in thoracic aortas from AngII-infused rats. Finally, both treatments significantly prevented the increase of inflammatory factors including monocyte chemotactic protein 1, intercellular adhesion molecule 1 and tumour necrosis factor α in thoracic aorta from AngII-infused rats. In conclusion, the present study demonstrates that the MR redox signalling pathway was involved in endothelial dysfunction and medial remodelling in AngII-induced hypertension.

Immune imbalance is associated with the development of preeclampsia

Preeclampsia (PE) is characterized by hypertension and proteinuria. It affects about 5% to 8% of pregnancies and causes maternal and perinatal mortality and morbidity. The immune imbalance and excessive inflammatory response play vital roles in the pathogenesis of PE.In this study, we performed a case-control study to investigate the levels of cytokines, chemokines and adhesion molecules in serum and placenta of normal pregnant and PE women by Bio-Plex multiplex immunoassay and immunohistochemistry. In addition, we explored the phenotypes of monocyte and macrophage in peripheral blood and placentas in 2 groups by using flow cytometry analysis and immunohistochemistry.Our results show that pro-inflammatory factors, including interleukin-1β (IL-1β), IL-6, IL-7, IL-8, IL-17a, monocyte chemotactic protein 1 (MCP -1), and macrophage inflammatory protein 1β (MIP-1β) were significantly increased in serum of women with PE compared with controls. In addition, we detected that IL-1β, IL-6, and MCP-1 were also increased in placentas of women with PE. We further revealed that peripheral blood monocytes showed a pro-inflammatory M1-like phenotype in women with PE. Consistently, M1 macrophage infiltration was increased in placenta of women with PE compared to that of normal pregnant women.Our results demonstrated that immune imbalance promotes an inflammatory state during PE and it may be a potential therapeutic possibility for the management of PE.

SGK1-FoxO1 Signaling Pathway Mediates Th17/Treg Imbalance and Target Organ Inflammation in Angiotensin II-Induced Hypertension

It has been demonstrated that serum/glucocorticoid regulated kinase 1 (SGK1) and the downstream transcription factor forkhead box O1 (FoxO1) plays a critical role in the differentiation of T helper 17 cells/regulatory T cells (Th17/Treg). In the present study, we hypothesized that this SGK1-FoxO1 signaling pathway is involved in Th17/Treg imbalance and target organ damage in angiotensin II (AngII)-induced hypertensive mice. Results show that SGK1 inhibitor EMD638683 significantly reversed renal dysfunction and cardiac dysfunction in echocardiography as indicated by decreased blood urine nitrogen and serum creatinine in AngII-infused mice. Flow cytometric assay shows that there was significant Th17/Treg imbalance in spleen and in renal/cardiac infiltrating lymphocytes as indicated by the increased Th17 cells (CD4⁺-IL17A⁺ cells) and decreased Treg cells (CD4⁺-Foxp3⁺). Consistently, real-time PCR shows that Th17-related cytokines including IL-17A, IL-23, and tumor necrosis factor α (TNF-α) was increased and Treg-related cytokine IL-10 was decreased in renal and cardiac infiltrating lymphocytes in AngII-infused mice. Meanwhile, SGK1 protein level, as well as its phosphorylation and activity, was significantly increased in spleen in AngII-infused rats. Furthermore, it was found that splenic phosphorylated FoxO1 was significantly increased, whereas total FoxO1 in nuclear preparation was significantly decreased in AngII-infused mice, suggesting that increased FoxO1 phosphorylation initiate its translocation from cytoplasm to nucleus. Notably, all changes were significantly inhibited by the treatment of EMD638683. These results suggest that SGK1 was involved in Th17/Treg imbalance and target organ damage in AngII-induced hypertension.

A2A Receptor Activation Attenuates Hypertensive Cardiac Remodeling via Promoting Brown Adipose Tissue-Derived FGF21

Adipocytes play important roles in regulating cardiovascular health and disease. However, the molecular mechanism underlying the endocrine role of brown adipose tissue (BAT) in pathological cardiac remodeling remains unknown. Herein we show that adenosine A_2A receptor (A_2AR) knockout (A_2ARKO) causes interscapular BAT (iBAT) dysfunction, leading to accelerated cardiac remodeling in hypertension compared with wild-type (WT) mice. Surgical iBAT depletion induces dramatic cardiac remodeling in WT but not in A_2ARKO hypertensive mice. AMPK/PGC1α signaling-induced fibroblast growth factor 21 (FGF21) in brown adipocytes is required for A_2AR-mediated inhibition of hypertensive cardiac remodeling. Recombinant FGF21 administration improves cardiac remodeling in iBAT-depleted hypertensive mice. More importantly, brown adipocyte-specific A_2ARKO inhibits FGF21 production and accelerates cardiac damage in hypertension. Consistently, brown adipocyte-specific FGF21 knockout abolishes the effects of A_2AR agonism in attenuating hypertensive cardiac remodeling. Our findings reveal a distinctive endocrine role of BAT in hypertensive cardiac remodeling via activating A_2AR/FGF21 pathway.

Perivascular Adipose Tissue-Derived PDGF-D Contributes to Aortic Aneurysm Formation During Obesity

Obesity increases the risk of vascular diseases, including aortic aneurysm (AA). Perivascular adipose tissue (PVAT) surrounding arteries are altered during obesity. However, the underlying mechanism of adipose tissue, especially PVAT, in the pathogenesis of AA is still unclear. Here we showed that angiotensin II (AngII) infusion increases the incidence of AA in leptin-deficient obese mice (ob/ob) and high-fat diet-induced obese mice with adventitial inflammation. Furthermore, transcriptome analysis revealed that platelet-derived growth factor-D (PDGF-D) was highly expressed in the PVAT of ob/ob mice. Therefore, we hypothesized that PDGF-D mediates adventitial inflammation, which provides a direct link between PVAT dysfunction and AA formation in AngII-infused obese mice. We found that PDGF-D promotes the proliferation, migration, and inflammatory factors expression in cultured adventitial fibroblasts. In addition, the inhibition of PDGF-D function significantly reduced the incidence of AA in AngII-infused obese mice. More importantly, adipocyte-specific PDGF-D transgenic mice are more susceptible to AA formation after AngII infusion accompanied by exaggerated adventitial inflammatory and fibrotic responses. Collectively, our findings reveal a notable role of PDGF-D in the AA formation during obesity, and modulation of this cytokine might be an exploitable treatment strategy for the condition.

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

KEY POINTS

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.

ABSTRACT

The membrane rafts (MRs)-redox pathway is characterized by NADPH oxidase subunit clustering and activation through lysosome fusion, V-type proton ATPase subunit E2 (encoded by the Atp6v1e2 gene) translocation and sphingomyelin phosphodiesterase 1 (SMPD1, encoded by the SMPD1 gene) activation. In the present study, we hypothesized that the MRs-redox-derived reactive oxygen species (ROS) are involved in renal inflammation and fibrosis by promoting renal tubular epithelial-mesenchymal transition (EMT). Results show that transforming growth factor-β1 (TGF-β1) acutely induced MR formation and ROS production in NRK-52E cells, a rat renal tubular cell line. In addition, transfection of Atp6v1e2 small hairpin RNAs (shRNA) and SMPD1 shRNA attenuated TGF-β1-induced changes in EMT markers, including E-cadherin, α-smooth muscle actin (α-SMA) and fibroblast-specific protein-1 (FSP-1) in NRK-52E cells. Moreover, Erk1/2 activation may be a downstream regulator of the MRs-redox-derived ROS, because both shRNAs significantly inhibited TGF-β1-induced Erk1/2 phosphorylation. Further in vivo study shows that the renal tubular the MRs-redox signalling pathway was activated in angiotensin II (AngII)-induced hypertension, as indicated by the increased NADPH oxidase subunit Nox4 fraction in the MR domain, SMPD1 activation and increased ROS content in isolated renal tubular cells. Finally, renal transfection of Atp6v1e2 shRNA and SMPD1 shRNA significantly prevented renal fibrosis and inflammation, as indicated by the decrease of α-SMA, fibronectin, collagen I, monocyte chemoattractant protein-1 (MCP-1), intercellular cell adhesion molecule-1 (ICAM-1) and tumour necrosis factor-α (TNF-α) in kidneys from AngII-infused rats. It was concluded that the the MRs-redox signalling pathway is involved in TGF-β1-induced renal tubular EMT and renal inflammation/fibrosis in AngII-induced hypertension.

Suppression of Endothelial-to-Mesenchymal Transition by SIRT (Sirtuin) 3 Alleviated the Development of Hypertensive Renal Injury

Endothelial-to-mesenchymal transition (EndoMT) has recently emerged as a potentially important contributor in promoting fibrosis in chronic kidney disease. However, little is known about the role and molecular basis of its involvement in hypertensive renal injury. Here, we aim to determine the role of SIRT (sirtuin) 3 on EndoMT in hypertensive renal injury and to explore its underlying mechanisms. We found that SIRT3 expression was significantly reduced in Ang II (angiotensin II)-induced hypertensive model, accompanied with induction of EndoMT and increased reactive oxygen species and renal fibrosis. In SIRT3^-/- (SIRT3 knockout) mice subjected to Ang II infusion, renal dysfunction was aggravated with an increased EndoMT and reactive oxygen species level, whereas in SIRT3-Tg^EC (SIRT3 endothelial cell-specific transgenic) mice, the Ang II-induced renal fibrosis and EndoMT and oxidative stress were ameliorated. With primary mouse glomerular endothelial cells, we confirmed that Ang II treatment initiated EndoMT and decreased catalase expression, which were suppressed by SIRT3 overexpression. Using immunoprecipitation, luciferase, and chromatin immunoprecipitation assay, we demonstrated that SIRT3-mediated deacetylation and nuclear localization of Foxo3a (forkhead box O3a) resulted in activated Foxo3a-dependent catalase expression. Moreover, Foxo3a knockdown abolished SIRT3-mediated suppression of EndoMT. In conclusion, these results established the SIRT3-Foxo3a-catalase pathway as a critical factor in the maintenance of endothelial homeostasis and point to an important role of EndoMT in the vascular pathology of renal fibrosis, which may provide a new therapeutic target to impede the progression of hypertensive renal injury.

Decrease of Perivascular Adipose Tissue Browning Is Associated With Vascular Dysfunction in Spontaneous Hypertensive Rats During Aging

Functional perivascular adipose tissue (PVAT) is necessary to maintain vascular physiology through both mechanical support and endocrine or paracrine ways. PVAT shows a brown adipose tissue (BAT)-like feature and the browning level of PVAT is dependent on the anatomic location and species. However, it is not clear whether PVAT browning is involved in the vascular tone regulation in spontaneously hypertensive rats (SHRs). In the present study, we aimed to illustrate the effect of aging on PVAT browning and subsequent vasomotor reaction in SHRs. Herein we utilized histological staining and western blot to detect the characteristics of thoracic PVAT (tPVAT) in 8-week-old and 16-week-old SHR and Wistar-Kyoto (WKY) rats. We also detected vascular reactivity analysis to determine the effect of tPVAT on vasomotor reaction during aging. The results showed that tPVAT had a similar phenotype to BAT, including smaller adipocyte size and positive uncoupling protein-1 (UCP1) staining. Interestingly, the tPVAT of 8-week-old SHR showed increased BAT phenotypic marker expression compared to WKY, whereas the browning level of tPVAT had a more dramatic decrease from 8 to 16 weeks of age in SHR than age-matched WKY rats. The vasodilation effect of tPVAT on aortas had no significant difference in 8-week-old WKY and SHR, whereas this effect is obviously decreased in 16-week-old SHR compared to WKY. In contrast, tPVAT showed a similar vasoconstriction effect in 8- or 16-week-old WKY and SHR rats. Moreover, we identified an important vasodilator adenosine, which regulates adipocyte browning and may be a potential PVAT-derived relaxing factor. Adenosine is dramatically decreased from 8 to 16 weeks of age in the tPVAT of SHR. In summary, aging is associated with a decrease of tPVAT browning and adenosine production in SHR rats. These may result in attenuated vasodilation effect of the tPVAT in SHR during aging.

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.

Deficiency of Complement C3a and C5a Receptors Prevents Angiotensin II-Induced Hypertension via Regulatory T Cells

RATIONALE

Inflammation and immunity play crucial roles in the development of hypertension. Complement activation-mediated innate immune response is involved in the regulation of hypertension and target-organ damage. However, whether complement-mediated T-cell functions could regulate blood pressure elevation in hypertension is still unclear.

OBJECTIVE

We aim to determine whether C3aR (complement component 3a receptor) and C5aR (complement component 5a receptor) could regulate blood pressure via modulating regulatory T cells (Tregs).

METHODS AND RESULTS

We showed that angiotensin II (Ang II)-induced hypertension resulted in an elevated expression of C3aR and C5aR in Foxp3 (forkhead box P3)+ Tregs. By using C3aR and C5aR DKO (double knockout) mice, we showed that C3aR and C5aR deficiency together strikingly decreased both systolic and diastolic blood pressure in response to Ang II compared with WT (wild type), single C3aR-deficient (C3aR-/-), or C5aR-deficient (C5aR-/-) mice. Flow cytometric analysis showed that Ang II-induced Treg reduction in the kidney and blood was also blocked in DKO mice. Histological analysis indicated that renal and vascular structure remodeling and damage after Ang II treatment were attenuated in DKO mice compared with WT mice. In vitro, Ang II was able to stimulate C3aR and C5aR expression in cultured CD4+CD25+ natural Tregs. CD3 and CD28 antibody stimuli downregulated Foxp3 expression in WT but not DKO Tregs. More important, depletion of Tregs with CD25 antibody abolished the protective effects against Ang II-induced hypertension and target-organ damage in DKO mice. Adoptive transfer of DKO Tregs showed much more profound protective effects against Ang II-induced hypertension than WT Treg transfer. Furthermore, we demonstrated that C5aR expression in Foxp3+ Tregs was higher in hypertensive patients compared with normotensive individuals.

CONCLUSIONS

C3aR and C5aR DKO-mediated Treg function prevents Ang II-induced hypertension and target-organ damage. Targeting C3aR and C5aR in Tregs specifically may be an alternative novel approach for hypertension treatment.

Complement 5a-mediated trophoblasts dysfunction is involved in the development of pre-eclampsia

Pre‐eclampsia (PE) is a life‐threatening multisystem disorder leading to maternal and neonatal mortality and morbidity. Emerging evidence showed that activation of the complement system is implicated in the pathological processes of PE. However, little is known about the detailed cellular and molecular mechanism of complement activation in the development of PE. In this study, we reported that complement 5a (C5a) plays a pivotal role in aberrant placentation, which is essential for the onset of PE. We detected an elevated C5a deposition in macrophages and C5a receptor (C5aR) expression in trophoblasts of pre‐eclamptic placentas. Further study showed that C5a stimulated trophoblasts towards an anti‐angiogenic phenotype by mediating the imbalance of angiogenic factors such as soluble fms‐like tyrosine kinase 1 (sFlt1) and placental growth factor (PIGF). Additionally, C5a inhibited the migration and tube formation of trophoblasts, while, C5aR knockdown with siRNA rescued migration and tube formation abilities. We also found that maternal C5a serum level was increased in women with PE and was positively correlated with maternal blood pressure and arterial stiffness. These results demonstrated that the placental C5a/C5aR pathway contributed to the development of PE by regulating placental trophoblasts dysfunctions, suggesting that C5a may be a novel therapeutic possibility for the disease.

Osteopontin regulates macrophage activation and osteoclast formation in hypertensive patients with vascular calcification

Vascular calcification (VC) is a highly regulated ectopic mineral deposition process involving immune cell infiltration in the vasculatures, which has been recognized to be promoted by hypertension. The matricellular glycoprotein osteopontin (OPN) is strongly induced in myeloid cells as a potential inflammatory mediator of vascular injury. This study aims to examine whether OPN is involved in the regulation of macrophage activation and osteoclast formation in hypertensive subjects with VC. We firstly found an increased proportion of CD11c+CD163- pro-inflammatory peripheral monocytes in hypertensive subjects with VC compared to those without VC by flow cytometric analysis. Primary cultured macrophages from hypertensive subjects with VC also showed altered expression profile of inflammatory factors and higher serum OPN level. Exogenous OPN promoted the differentiation of peripheral monocytes into an alternative, anti-inflammatory phenotype, and inhibited macrophage-to-osteoclast differentiation from these VC patients. In addition, calcified vessels showed increased osteoclasts accumulation accompanied with decreased macrophages infiltration in the of hypertensive subjects. Taken together, these demonstrated that OPN exerts an important role in the monocytes/macrophage phenotypic differentiation from hypertensive patients with VC, which includes reducing inflammatory factor expression and attenuating osteoclast formation.

Adenovirus-Mediated Overexpression of Septin 2 Attenuates α-Smooth Muscle Actin Expression and Adventitial Myofibroblast Migration Induced by Angiotensin II

Phenotypic transformation from adventitial fibroblasts (AFs) to myofibroblasts (MFs) is critical for vascular remodeling. Septin 2 was found to be downregulated during the differentiation of AFs to MFs induced by angiotensin II (Ang II); however, the role of septin 2 in this process is still unknown. In this study, we investigate whether septin 2 contributes to the adventitial MF phenotypic modulation caused by Ang II. The decreased level of septin 2 and the increased expression of α-smooth muscle actin (α-SMA), a marker of MFs, were readily observed in Ang II-stimulated MF differentiation. After gene transfer of septin 2, the expression of α-SMA was markedly decreased and the MF migration response to Ang II was inhibited. Furthermore, the inhibition of RhoA, another molecule involved in MF phenotypic modulation, decreased the motility of MFs and the expression of septin 2 triggered in Ang II. Finally, transfection of septin 2 rescued the level of acetyl-α-tubulin in MFs. These findings demonstrate that, as a downstream molecule of RhoA, septin 2 blunted the responses of AFs to Ang II by protecting α-tubulin acetylation, which suggests that septin 2 may serve as a potential therapeutic target for vascular injury.

Mitochondrial division inhibitor Mdivi-1 ameliorates angiotensin II-induced endothelial dysfunction

Mitochondrial fission can occur via activation of dynamin-related protein 1 (Drp1), which participates in the mitochondrial membrane scission process. The present study was designed to investigate the effect of angiotensin II (AngII) on mitochondrial fission and fusion in human umbilical vascular endothelial cells (HUVECs). And we further inquire into whether Mdivi-1, a newly identified pharmacological inhibitor of Drp1, can prevent endothelial dysfunction induced by AngII. The HUVECs were treated with AngII alone or in combination with Mdivi-1. Western blot was used to detect protein expressions of Drp1, endothelial nitric oxide synthase (eNOS) and apoptosis-related enzymes. MitoTracker Red and JC-1 dye were used to detect mitochondrial morphology and membrane potential, respectively. DCFH-DA probe was used to access intracellular reactive oxygen species (ROS) generation. Transwell assay was used to evaluate cell migration. Annexin V/PI staining was used to assess cellular apoptosis. The results showed that, in cultured HUVECs, AngII (1 × 10^-7 mol/L, 12 h) treatment significantly upregulated the expression of Drp1 followed by increased apoptosis and decreased eNOS expression. The treatment of AngII resulted in a change in mitochondrial morphology from elongated to uniformly punctate organelles, which was accompanied by decreased mitochondrial membrane potential. Furthermore, Mdivi-1 significantly protected against AngII-induced endothelial dysfunction, as shown by increased mitochondrial membrane potential and eNOS expression, reduced ROS level, decreased apoptosis and migration ability. Taking together, our data suggest that inhibition of Drp1 with Mdivi-1 can restore AngII-induced endothelial dysfunction.

Association of a SNP in SLC35F3 Gene with the Risk of Hypertension in a Chinese Han Population

A recent study suggested that SLC35F3 which encoded a thiamine transporter was a new candidate gene for hypertension. The goal of this study was to investigate the association between the single-nucleotide polymorphisms (SNPs) in the SLC35F3 gene and hypertension in a Chinese population. Sanger sequencing was performed in 93 samples to find SNPs in coding regions and intron–exon boundaries in the SLC35F3 gene. We found eight genetic variants in the coding regions of SLC35F3 and subsequently genotyped a non-synonymous variant rs34032258 (C > G) in 1060 hypertension patients and 1467 controls. After adjusting for age and gender, multivariate analysis of covariance showed that the variant was associated with hypertensive traits. In detail, diastolic blood pressure (DBP) was 8 mmHg higher, blood urea nitrogen was 12 mmol/L higher, and creatinine was 15 mmol/L lower in G/G group compared with C/C group (p = 0.007; 0.012 and 0.029, respectively). Further study suggested that C/G+G/G had higher DBP than C/C genotype in those whose DBP ≥ 90 mmHg (98.02 mmHg vs. 94.04 mmHg, p = 0.021). No significant difference has been found in systolic blood pressure between different genotypes. Additionally, in the subgroup of obesity, allele distribution of this variant has shown significant difference between hypertensive patients and normotensive controls (p = 0.018). In conclusion, we found that the rs34032258 in the SLC35F3 gene was associated with high blood pressure and may increase the risk of hypertension. The new hypertension-susceptibility locus may involve in the pathogenesis of hypertension and indicate some novel treatment implications.

Differential ERK1/2 Signaling and Hypertrophic Response to Endothelin-1 in Cardiomyocytes from SHR and Wistar-Kyoto Rats: A Potential Target for Combination Therapy of Hypertension

Extracellular signal regulated kinase½ (ERK1/2) signaling is critical to endothelin-1 (ET-1)-induced cardiomyocyte hypertrophy. This study was to investigate ERK1/2 signaling and hypertrophic response to ET-1 stimulation in cardiomyocytes (CMs) from spontaneous hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). Primary neonatal SHR and WKY CMs were exposed to ET-1 for up to 24 hrs. Minimal basal ERK1/2 phosphorylation was present in WKY CMs, while a significant baseline ERK1/2 phosphorylation was observed in SHR CMs. ET-1 induced a time- and dose-dependent increase in ERK1/2 phosphorylation in both SHR and WKY CMs. However, ET-1-induced ERK1/2 activation occurred much earlier with significantly higher peak phosphorylation level, and stayed elevated for longer duration in SHR CMs than that in WKY CMs. ET-1-induced hypertrophic response was more prominent in SHR CMs than that in WKY CMs as reflected by increased cell surface area, intracellular actin density, and protein synthesis. Pre-treatment with ERK1/2 phosphorylation inhibitor PD98059 completely prevented ET-1-induced ERK1/2 phosphorylation and increases in cell surface area and protein synthesis in SHR and WKY CMs. The specific PI3 kinase inhibitor LY294002 blocked ET-1-induced Akt and ERK1/2 phosphorylation, and protein synthesis in CMs. These data indicated that ERK1/2 signaling was differentially enhanced in CMs, and was associated with increased cardiac hypertrophic response to ET-1 in SHR. ET-1-induced ERK1/2 activation and cardiac hypertrophy appeared to be mediated via PI3 kinase/Akt signaling in SHR and WKY. The differential ERK1/2 activation in SHR CMs by ET-1 might represent a potential target for combination therapy of hypertension.

Protease-activated receptor 1 and 2 contribute to angiotensin II-induced activation of adventitial fibroblasts from rat aorta

Adventitial fibroblasts (AFs) can be activated by angiotensin II (Ang II) and exert pro-fibrotic and pro-inflammatory effects in vascular remodeling. Protease-activated receptor (PAR) 1 and 2 play a significant role in fibrogenic and inflammatory diseases. The present study hypothesized that PAR1 and PAR2 are involved in Ang II-induced AF activation and contribute to adventitial remodeling. We found that direct activation of PAR1 and PAR2 with PAR1-AP and PAR2-AP led to AF activation, including proliferation and differentiation of AFs, extracellular matrix synthesis, as well as production of pro-fibrotic cytokine TGF-β and pro-inflammatory cytokines IL-6 and MCP-1. Furthermore, PAR1 and PAR2 mediated Ang II-induced AF activation, since both PAR1 and PAR2 antagonists inhibited Ang II-induced proliferation, migration, differentiation, extracellular matrix synthesis and production of pro-fibrotic and pro-inflammatory cytokines in AFs. Finally, mechanistic study showed that Ang II, via Ang II type I receptor (AT1R), upregulated both PAR1 and PAR2 expression, and transactivated PAR1 and PAR2, as denoted by internalization of both proteins. In conclusion, our results suggest that PAR1 and PAR2 play a critical role in Ang II-induced AF activation, and this may contribute to adventitia-related pathological changes.

Beta3 adrenergic receptor is involved in vascular injury in deoxycorticosterone acetate-salt hypertensive mice

Beta3 adrenergic receptor (ADRB3) mediates vessel relaxation in the endothelium while it modulates lipolysis in the adipose tissue. However, the function and regulation mechanism of ADRB3 in the perivascular adipose tissue (PVAT), especially in hypertension, is still unclear. We show that ADRB3 protein is upregulated in the PVAT of deoxycorticosterone acetate-salt (DOCA-salt) hypertensive mice, with the characteristics of PVAT browning and increased uncoupling protein 1 (UCP1) expression. Inhibition of ADRB3 with selective antagonist SR59230A caused serious vascular injury in vivo, even though UCP1 expression was downregulated. ADRB3 protein was regulated by let-7b, which was decreased in the PVAT of the DOCA-salt group. These data reveal that ADRB3 in PVAT contributes to vascular function in the progression of hypertension.

Activating transcription factor 3 SUMOylation is involved in angiotensin II-induced endothelial cell inflammation and dysfunction

Activating transcription factor 3 (ATF3) is an adaptive-response protein induced by various environmental stresses and is implicated in the pathogenesis of many disease states. However, the role of ATF3 SUMOylation in hypertension-induced vascular injury remains poorly understood. Here we investigated the function of ATF3 SUMOylation in vascular endothelial cells (ECs). The expression of ATF3 and small ubiquitin-like modifier 1 (SUMO1) was increased in angiotensin II (Ang II)-induced human umbilical vein endothelial cells (HUVECs). Microscopic analyses further revealed that the expression of ATF3 and SUMO1 is upregulated and colocalized in the endothelium of thoracic aortas from Ang II-induced hypertensive mice. However, Ang II-induced upregulation of ATF3 and SUMO1 in vitro and in vivo was blocked by Ang II type I receptor antagonist olmesartan. Moreover, Ang II induced ATF3 SUMOylation at lysine 42, which is SUMO1 dependent. ATF3 SUMOylation attenuated ATF3 ubiquitination and in turn promoted ATF3 protein stability. ATF3 or SUMO1 knockdown inhibited Ang II-induced expression of inflammatory molecules such as tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-8. Wild type ATF3 but not ATF3-K42R (SUMOylation defective mutant) reduced the production of nitric oxide (NO), a key indicator of EC function. Consistently, ginkgolic acid, an inhibitor of SUMOylation, increased NO production in HUVECs and significantly improved vasodilatation of aorta from Ang II-induced hypertensive mice. Our findings demonstrated that ATF3 SUMOylation is involved in Ang II-induced EC inflammation and dysfunction in vitro and in vivo through inhibiting ATF3 ubiquitination and increasing ATF3 protein stability.

[Angiotensin II induces expression of inflammatory mediators in vascular adventitial fibroblasts]

Vascular adventitial fibroblasts (AF) may play an important role in vascular inflammation. This study was aimed to investigate the expression pattern of inflammatory mediators in AF induced by angiotensin II (AngII) and to explore the effects of AF-derived inflammatory mediators on the adhesion and migration of macrophages both in vitro and in vivo. We used real-time RT-PCR to detect the mRNA expression of inflammatory mediators in cultured AF. The results showed that AngII (1 × 10(-7) mol/L) up-regulated mRNA expression of 4 inflammatory mediators, including P-selectin, ICAM-1, IL-6 and MCP-1, in cultured AF. Western blot analysis or ELISA revealed that AngII up-regulated P-selectin and ICAM-1 protein expression and IL-6 secretion in cultured AF, but did not alter MCP-1 secretion. We further detected the effects of AF-derived inflammatory mediators on the adhesion and chemotaxis of RAW264.7, a macrophage cell line. We found that AF stimulated with AngII could enhance the adhesion of RAW264.7 and the conditioned medium from AngII-stimulated AF could enhance the migration of RAW264.7. Immunofluorescence study showed an enhanced accumulation of CD68 positive cells and the up-regulation of P-selectin, ICAM-1, IL-6 and MCP-1 in aortic adventitia of AngII-infused (200 ng/kg per min for 2 weeks) rats. We concluded that AF may contribute to vascular inflammation via expression of certain inflammatory mediators and the subsequent adhesion and chemotaxis of macrophages.

Deletion of angiotensin-converting enzyme 2 exacerbates renal inflammation and injury in apolipoprotein E-deficient mice through modulation of the nephrin and TNF-alpha-TNFRSF1A signaling

Background

The renin-angiotensin system (RAS) has been implicated in atherosclerotic lesions and progression to chronic kidney diseases. We examined regulatory roles of angiotensin-converting enzyme 2 (ACE2) in the apolipoprotein E (ApoE) knockout (KO) kidneys.

Methods

The 3-month-old wild-type, ApoEKO, ACE2KO and ApoE/ACE2 double-KO (DKO) mice in a C57BL/6 background were used. The ApoEKO mice were randomized to daily deliver either Ang II (1.5 mg/kg) and/or human recombinant ACE2 (rhACE2; 2 mg/kg) for 2 weeks. We examined changes in pro-inflammatory cytokines, renal ultrastructure, and pathological signaling in mouse kidneys.

Results

Downregulation of ACE2 and nephrin levels was observed in ApoEKO kidneys. Genetic ACE2 deletion resulted in modest elevations in systolic blood pressure levels and Ang II type 1 receptor expression and reduced nephrin expression in kidneys of the ApoE/ACE2 DKO mice with a decrease in renal Ang-(1-7) levels. These changes were linked with marked increases in renal superoxide generation, NADPH oxidase (NOX) 4 and proinflammatory factors levels, including interleukin (IL)-1beta, IL-6, IL-17A, RANTES, ICAM-1, Tumor necrosis factor-alpha (TNF-alpha) and TNFRSF1A. Renal dysfunction and ultrastructure injury were aggravated in the ApoE/ACE2 DKO mice and Ang II-infused ApoEKO mice with increased plasma levels of creatinine, blood urea nitrogen and enhanced levels of Ang II in plasma and kidneys. The Ang II-mediated reductions of renal ACE2 and nephrin levels in ApoEKO mice were remarkably rescued by rhACE2 supplementation, along with augmentation of renal Ang-(1-7) levels. More importantly, rhACE2 treatment significantly reversed Ang II-induced renal inflammation, superoxide generation, kidney dysfunction and adverse renal injury in ApoEKO mice with suppression of the NOX4 and TNF-alpha-TNFRSF1A signaling. However, rhACE2 had no effect on renal NOX2 and TNFRSF1B expression and circulating lipid levels.

Conclusions

ACE2 deficiency exacerbates kidney inflammation, oxidative stress and adverse renal injury in the ApoE-mutant mice through modulation of the nephrin, NOX4 and TNF-alpha-TNFRSF1A signaling. While rhACE2 supplementation alleviates inflammation, renal dysfunction and glomerulus injury in the ApoE-mutant mice associated with upregulations of Ang-(1-7) levels and nephrin expression and suppression of the TNF-alpha-TNFRSF1A signaling. Strategies aimed at enhancing the ACE2/Ang-(1-7) actions may have important therapeutic potential for atherosclerotic renal injury and kidney diseases.

Downregulation of Dynamin-Related Protein 1 Contributes to Impaired Autophagic Flux and Angiogenic Function in Senescent Endothelial Cells

Objective—

Recent studies have shown that altered mitochondrial dynamics impairs the function in senescent endothelial cells (ECs). However, the underlying molecular mechanism remains to be elucidated. Herein, we investigated the role and underlying mechanism of mitochondrial fission protein dynamin-related protein 1 (DRP1) in vascular aging.

Approach and Results—

We found that DRP1 expression is decreased in senescent ECs, accompanied with long interconnected mitochondria and impaired angiogenic function. In addition, there was marked increase of autophagosomes but not of autolysosomes (assessed as punctate dual fluorescent mCherry-GFP (green fluorescent protein) tandem-tagged light chain 3 expression) in senescent ECs, indicating impaired autophagic flux. DRP1 knockdown or pharmacological inhibition in young ECs resulted in elongated mitochondria, suppressed autophagic flux, premature senescence, and impaired angiogenic function. In contrast, adenoviral-mediated overexpression of DRP1 in senescent ECs restored autophagic flux and improved angiogenic function. EC senescence was associated with the increase of mitochondrial reactive oxygen species and antioxidant N-acetyl-cysteine restored autophagosome clearance and improved angiogenic function. Consistently, en face staining of old rat thoracic aorta revealed a decrease of DRP1 expression and increase of autophagosomes accumulation. Furthermore, in vivo knockdown of Drp1 in common carotid arteries significantly impaired the autophagosome clearance. Importantly, downregulation of Drp1 directly abrogated microvessels outgrowth from ex vivo aortic rings.

Conclusions—

These results suggest that loss of DRP1 during senescence exacerbates ECs dysfunction by increasing mitochondrial reactive oxygen species and subsequently inhibiting autophagic flux.

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.

Adventitial gene transfer of catalase attenuates angiotensin II-induced vascular remodeling

Vascular adventitia and adventitia-derived reactive oxygen species (ROS) contribute to vascular remodeling following vascular injury. A previous ex vivo study in adventitial fibroblasts showed that catalase, one of most important anti-oxide enzymes, was downregulated by angiotensin II (AngII). The aim of the present study was to investigate whether adventitial gene transfer of catalase affects AngII-induced vascular remodeling in vivo. Adenoviruses co-expressing catalase and enhanced green fluorescent protein (eGFP) or expressing eGFP only were applied to the adventitial surface of common carotid arteries of Sprague-Dawley rats. Alzet minipumps administering AngII (0.75 mg/kg/day) were then implanted subcutaneously for 14 days. Systolic blood pressure and biological parameters of vascular remodeling were measured in each group. Adventitial fibroblasts were cultured and p38 mitogen-activated protein kinase (MAPK) phosphorylation was measured using western blot analysis. The results showed that adventitial gene transfer of catalase had no effect on AngII-induced systolic blood pressure elevation. However, catalase adenovirus transfection significantly inhibited AngII-induced media hypertrophy compared with that of the control virus (P<0.05). In addition, catalase transfection significantly attenuated AngII-induced ROS generation, macrophage infiltration, collagen deposition and adventitial α-smooth muscle actin expression. Furthermore, catalase transfection significantly inhibited the AngII-induced increase in p38MAPK phosphorylation. In conclusion, the results of the present study demonstrated that adventitial gene transfer of catalase significantly attenuated AngII-induced vascular remodeling in rats via inhibition of adventitial p38MAPK phosphorylation.