Mac-1 deficiency ameliorates pressure overloaded heart failure through inhibiting macrophage polarization and activation.

Persistent pressure overload commonly leads to pathological cardiac hypertrophy and remodeling, ultimately leading to heart failure (HF). Cardiac remodeling is associated with the involvement of immune cells and the inflammatory response in pathogenesis. The macrophage-1 antigen (Mac-1) is specifically expressed on leukocytes and regulates their migration and polarization. Nonetheless, the involvement of Mac-1 in cardiac remodeling and HF caused by pressure overload has not been determined. The Mac-1-knockout (KO) and wild-type (WT) mice were subjected to transverse aortic constriction (TAC) for 6 weeks. Echocardiography and pressure-volume loop assessments were used to evaluate cardiac function, and cardiac remodeling and macrophage infiltration and polarization were estimated by histopathology and molecular techniques. The findings of our study demonstrated that Mac-1 expression was markedly increased in hearts subjected to TAC treatment. Moreover, compared with WT mice, Mac-1-KO mice exhibited dramatically ameliorated TAC-induced cardiac dysfunction, hypertrophy, fibrosis, oxidative stress and apoptosis. The potential positive impacts may be linked to the inhibition of macrophage infiltration and M1 polarization via reductions in NF-kB and STAT1 expression and upregulation of STAT6. In conclusion, this research reveals a new function of Mac-1 deficiency in reducing pathological cardiac remodeling and HF caused by pressure overload. Additionally, inhibiting Mac-1 could be a potential treatment option for patients with HF in a clinical setting.

CD11b mediates hypertensive cardiac remodeling by regulating macrophage infiltration and polarization.

INTRODUCTION: Leukocyte infiltration is an early event during cardiac remodeling frequently leading to heart failure (HF). Integrins mediate leukocyte infiltration during inflammation. However, the importance of specific integrins in hypertensive cardiac remodeling is still unclear. OBJECTIVES: To elucidate the significance of CD11b in hypertensive cardiac remodeling. METHODS: Angiotensin (Ang II) or deoxycorticosterone acetate (DOCA)-salt was used to induce cardiac remodeling in mice of gene knockout (KO), bone marrow (BM) chimera, and the CD11b neutralizing antibody or agonist leukadherin-1 (LA1) treatment. RESULTS: Our microarray data showed that integrin subunits Itgam (CD11b) and Itgb2 (CD18) were the most highly upregulated in Ang II-infused hearts. CD11b expression and CD11b/CD18+ myelomonocytes were also time-dependently increased. KO or pharmacological blockade of CD11b greatly attenuated cardiac remodeling and macrophage infiltration and M1 polarization induced by Ang II or DOCA-salt. This protection was verified in wild-type mice transplanted with CD11b-deficient BM cells. Conversely, administration of CD11b agonist LA1 showed the opposite effects. Further, CD11b KO reduced Ang II-induced macrophage adhesion and M1 polarization, leading to reduction of cardiomyocyte enlargement and fibroblast differentiation in vitro. The numbers of CD14+CD11b+CD18+ monocytes and CD15+CD11b+CD18+ granulocytes were obviously higher in HF patients than in normal controls. CONCLUSION: Our data demonstrate an important role of CD11b+ myeloid cells in hypertensive cardiac remodeling, and suggest that HF may benefit from targeting CD11b.

Biochanin A inhibits cardiac hypertrophy and fibrosis in vivo and in vitro.

The heart undergoes pathological cardiac hypertrophy as an adaptive response to prolonged pathological stimulation, leading to cardiomyocyte hypertrophy, fibroblast proliferation, and an increase in extracellular matrix. Chinese medicine monomers are now receiving much attention for the treatment of cardiac hypertrophy and myocardial remodeling. Biochanin A (BCA) is a kind of flavonoid structural monomer, which has a certain therapeutic effect on bone thinning disease, aging syndrome, lung cancer, etc. Moreover, it exhibits hypoglycemic, anti-inflammatory, anti-oxidation, anti-bacteria and other pharmacological properties. It is still unknown whether BCA has an impact on the mechanism of TAC-induced cardiac hypertrophy. Here, cardiac remodeling was induced by TAC. BCA was injected intraperitoneally at 25 and 50 mg/kg/day one week in advance. Masson, WGA, DHE and other pathological staining and serum were used to detect the inhibitory effect of BCA on cardiac hypertrophy in mice. The anti-hypertrophic effect of BCA was demonstrated by studying the pathological manifestations of Neonatal rat cardiomyocytes (NRCMs) and cardiac fibroblasts (CFs) in vitro. The results showed that BCA significantly reduced TAC-induced fibrosis, inflammation, oxidative stress, and myocardial hypertrophy. BCA inhibited Ang II-induced cell hypertrophy and oxidative stress in NRCMs in vitro and Ang II-induced CF migration, proliferation, and collagen secretion. This suggests that BCA plays a key role in inhibiting the progression of myocardial remodeling, suggesting that BCA may be a promising agent for the treatment of myocardial hypertrophy and fibrosis.

ATGL deficiency aggravates pressure overload-triggered myocardial hypertrophic remodeling associated with the proteasome-PTEN-mTOR-autophagy pathway.

Persistent myocardial hypertrophy frequently leads to heart failure (HF). Intramyocardial triacylglycerol (TAG) accumulation is closely related with cardiac remodeling and abnormal contractile function. Adipose triglyceride lipase (ATGL), a key enzyme in TAG metabolism, regulates cardiac function. However, its associated molecular pathways have not been fully defined. Here, cardiac hypertrophy and HF were induced in wild-type (WT) or ATGL knockout (KO) mice through transverse aortic constriction (TAC) for up to 4 weeks. TAC in WT mice significantly reduced cardiac function and autophagy while enhancing left ventricular hypertrophy, interstitial fibrosis, inflammatory response, superoxide generation, and cardiomyocyte apoptosis, accompanied with upregulation of the proteasome activity, reduction of PTEN level and activation of AKT-mTOR signaling, and these effects were further aggravated in ATGL KO mice. Interestingly, ATGL KO-mediated cardiac dysfunction and remodeling were markedly reversed by proteasome inhibitor (epoxomicin) or autophagic activator (rapamycin), but accelerated by PTEN inhibitor (VO-OHpic) or autophagy inhibitor 3-MA. Mechanistically, ATGL KO upregulated proteasome expression and activity, which in turn mediates PTEN degradation leading to activation of AKT-mTOR signaling and inhibition of autophagy, thereby enhancing hypertrophic remodeling and HF. In conclusion, ATGL KO contributes to TAC-induced cardiac dysfunction and adverse remodeling probably associated with the proteasome-PTEN-mTOR-autophagy pathway. Therefore, modulation of this pathway may have a therapeutic effect potential for hypertrophic heart disease. TAC-induced downregulation of ATGL results in increased proteasome (ß1i/ß2i/ß5i) activity, which in turn promotes degradation of PTEN and activation of AKT-mTOR signaling and then inhibits autophagy and ATP production, thereby leading to cardiac hypertrophic remodeling and dysfunction. Conversely, blocking proteasome activity or activating autophagy attenuates these effects.

Integrin CD11b Contributes to Hypertension and Vascular Dysfunction Through Mediating Macrophage Adhesion and Migration.

BACKGROUND: Leukocyte adhesion to endothelium is an early inflammatory response and is mainly controlled by the ß2-integrins. However, the role of integrin CD11b/CD18 in the pathogenesis of hypertension and vascular dysfunction is unclear. METHODS: Hypertension was established by angiotensin II (490 ng/kg·per min) or deoxycorticosterone acetate salt. Hypertensive responses were studied in CD11b-deficient (CD11b-/-) mice, bone marrow transplanted and wild-type (WT) mice that were administered anti-CD11b neutralizing antibody or agonist leukadherin-1. Blood pressure was monitored with tail-cuff method and radiotelemetry. Blood and vascular inflammatory cells were assessed by flow cytometry. Aortic remodeling and function were examined using histology and aortic ring analysis. Cell adhesion and migration were evaluated in vitro. The relationship between circulating CD11b+ immune cells and hypertension was analyzed in patients with hypertension. RESULTS: We found that CD11b and CD18 expression as well as the CD45+CD11b+CD18+ myeloid cells were highly increased in the aorta of angiotensin II-infused mice. Ablation or pharmacological inhibition of CD11b in mice significantly alleviated hypertension, aortic remodeling, superoxide generation, vascular dysfunction, and the infiltration of CD11b+ macrophages through reducing macrophage adhesion and migration. These effects were confirmed in WT mice reconstituted with CD11b-deficient bone marrow cells. Conversely, angiotensin II-induced hypertensive response was exacerbated by CD11b agonist leukadherin-1. Notably, circulating CD45+CD11b+CD18+ myeloid cells and the ligand levels in hypertensive patients were significantly higher than in normotensive controls. CONCLUSIONS: We demonstrated a critical significance of CD11b+ myeloid cells in hypertension and vascular dysfunction. Targeting CD11b may represent a novel therapeutic option for hypertension.

Blocking VCAM-1 ameliorates hypertensive cardiac remodeling by impeding macrophage infiltration.

Cardiac remodeling is an important mechanism of heart failure, which frequently results from leukocyte infiltration. Vascular cellular adhesion molecule-1 (VCAM-1) plays a critical role in leukocyte adhesion and transmigration. However, the importance of VCAM-1 in the development of angiotensin II (Ang II)-induced cardiac remodeling remains unclear. Wild-type (WT) mice were infused with Ang II (1,000 ng/kg/min) for 14 days and simultaneously treated with VCAM-1 neutralizing antibody (0.1 or 0.2 mg) or IgG control. Systolic blood pressure (SBP) and cardiac function were detected by a tail-cuff and echocardiography. Cardiac remodeling was evaluated by histological staining. Adhesion and migration of bone marrow macrophages (BMMs) were evaluated in vitro. Our results indicated that VCAM-1 levels were increased in the serum of patients with heart failure (HF) and the hearts of Ang II-infused mice. Furthermore, Ang II-caused hypertension, cardiac dysfunction, hypertrophy, fibrosis, infiltration of VLA-4+ BMMs and oxidative stress were dose-dependently attenuated in mice administered VCAM-1 neutralizing antibody. In addition, blocking VCAM-1 markedly alleviated Ang II-induced BMMs adhesion and migration, therefore inhibited cardiomyocyte hypertrophy and fibroblast activation. In conclusion, the data reveal that blocking VCAM-1 ameliorates hypertensive cardiac remodeling by impeding VLA-4+ macrophage infiltration. Selective blockage of VCAM-1 may be a novel therapeutic strategy for hypertensive cardiac diseases.

CXCL1-CXCR2 signalling mediates hypertensive retinopathy by inducing macrophage infiltration.

Inflammation plays an important role in hypertensive retinal vascular injury and subsequent retinopathy. Monocyte chemotaxis via CXCL1-CXCR2 binding has been implicated in various cardiovascular diseases, but the function of CXCL1-CXCR2 signalling involved in retinopathy, which was investigated as angiotensin II (Ang II)-induced retinopathy, is unclear. In our study, we established a hypertensive retinopathy (HR) model by Ang II infusion (3000 ng/min/kg) for 3 weeks. To determine the involvement of CXCR2 signalling, we used CXCR2 knockout (KO) mice or C57BL/6J wild-type (WT) mice as experimental subjects. The mice were treated with a CXCL1 neutralizing antibody or SB225002 (the specific CXCR2 inhibitor). Our results showed that after Ang II treatment, the mRNA levels of CXCL1 and CXCR2 and the number of CXCR2+ inflammatory cells were significantly elevated. Conversely, unlike in the IgG control group, the CXCL1 neutralizing antibody greatly reduced the increase in central retinal thickness induced by Ang II infusion, arteriolar remodelling, superoxide production, and retinal dysfunction in WT mice. Furthermore, Ang II infusion induced arteriolar remodelling, infiltration of Iba1+ macrophages, the production of oxidative stress, and retinal dysfunction, but the symptoms were ameliorated in CXCR2 KO mice and SB225002-treated mice. These protective effects were related to the reduction in the number of CXCR2+ immune cells, particularly macrophages, and the decrease in proinflammatory cytokine (IL-1ß, IL-6, TNF-ɑ, and MCP-1) expression in Ang II-treated retinas. Notably, serum CXCL1 levels and the number of CXCR2+ monocytes/neutrophils were higher in HR patients than in healthy controls. In conclusion, this study provides new evidence that the CXCL1-CXCR2 axis plays a vital role in the pathogenesis of hypertensive retinopathy, and selective blockade of CXCL1-CXCR2 activation may be a potential treatment for HR.

Low-Dose Gallic Acid Administration Does Not Improve Diet-Induced Metabolic Disorders and Atherosclerosis in Apoe Knockout Mice.

Diets rich in polyphenols are known to be beneficial for cardiovascular health. Gallic acid (GA) is a plant-derived triphenolic chemical with multiple cardio-protective properties, such as antiobesity, anti-inflammation, and antioxidation. However, whether GA could protect against atherosclerotic cardiovascular diseases is still not defined. Here, we investigated the effects of low-dose GA administration on diet-induced metabolic disorders and atherosclerosis in the atherosclerosis-prone apolipoprotein E (Apoe) knockout mice fed on a high-fat Western-type diet (WTD) for 8 weeks. Our data showed that GA administration by oral gavage at a daily dosage of 20 mg/kg body weight did not significantly ameliorate WTD-induced hyperlipidemia, hepatosteatosis, adipogenesis, or insulin resistance; furthermore, GA administration did not significantly ameliorate WTD-induced atherosclerosis. In conclusion, our data demonstrate that low-dose GA administration does not elicit significant health effect on diet-induced metabolic disorders or atherosclerosis in the Apoe knockout mice. Whether GA could be beneficial for atherosclerotic cardiovascular diseases therefore needs further exploration.

Blocking VCAM-1 Prevents Angiotensin II-Induced Hypertension and Vascular Remodeling in Mice.

Adhesion of monocytes to the vascular endothelium frequently leads to an inflammatory response, which contributes to hypertension and vascular remodeling. Vascular cellular adhesion molecule-1 (VCAM-1) plays an important role in leukocyte adhesion and migration during inflammatory diseases. However, its role in angiotensin (Ang) II -induced hypertension and vascular dysfunction remains largely unknown. Wild-type (WT) mice were administered a VCAM-1 neutralizing antibody (0.1 or 0.2 mg/mouse/day) or IgG control and then infused with Ang II (490 ng kg-1 min-1) or saline continuously for 14 days. Systolic blood pressure (SBP) was measured with a tail-cuff system, pathological changes in the aorta were assessed by histological staining, and vascular relaxation was analyzed an aortic ring assay. Our results indicated that compared with saline infusion, Ang II infusion significantly upregulated VCAM-1 expression in the mouse aorta and serum. Moreover, Ang II infusion markedly increased arterial hypertension, wall thickness, fibrosis, infiltration of Mac-2+ macrophages, reactive oxygen species (ROS) production and vascular relaxation dysfunction. Conversely, blockade of VCAM-1 with a neutralizing antibody substantially alleviated these effects. In vitro experiments further confirmed that the VCAM-1 neutralizing antibody inhibited Ang II-induced macrophage adhesion and migration and DNA damage and oxidative stress in endothelial cells (ECs). In conclusion, these results indicate that blockade of VCAM-1 exerts a protective effect against Ang II-induced arterial hypertension and dysfunction by regulating monocytes adhesion and infiltration into the endothelium and represents a novel therapeutic approach for hypertension.

Angiotensin II Induces Cardiac Edema and Hypertrophic Remodeling through Lymphatic-Dependent Mechanisms.

Cardiac lymphatic vessel growth (lymphangiogenesis) and integrity play an essential role in maintaining tissue fluid balance. Inhibition of lymphatic lymphangiogenesis is involved in cardiac edema and cardiac remodeling after ischemic injury or pressure overload. However, whether lymphatic vessel integrity is disrupted during angiotensin II- (Ang II-) induced cardiac remodeling remains to be investigated. In this study, cardiac remodeling models were established by Ang II (1000 ng/kg/min) in VEGFR-3 knockdown (Lyve-1Cre VEGFR-3f/-) and wild-type (VEGFR-3f/f) littermates. Our results indicated that Ang II infusion not only induced cardiac lymphangiogenesis and upregulation of VEGF-C and VEGFR-3 expression in the time-dependent manner but also enhanced proteasome activity, MKP5 and VE-cadherin degradation, p38 MAPK activation, and lymphatic vessel hyperpermeability. Moreover, VEGFR-3 knockdown significantly inhibited cardiac lymphangiogenesis in mice, resulting in exacerbation of tissue edema, hypertrophy, fibrosis superoxide production, inflammation, and heart failure (HF). Conversely, administration of epoxomicin (a selective proteasome inhibitor) markedly mitigated Ang II-induced cardiac edema, remodeling, and dysfunction; upregulated MKP5 and VE-cadherin expression; inactivated p38 MAPK; and reduced lymphatic vessel hyperpermeability in WT mice, indicating that inhibition of proteasome activity is required to maintain lymphatic endothelial cell (LEC) integrity. Our results show that both cardiac lymphangiogenesis and lymphatic barrier hyperpermeability are implicated in Ang II-induced adaptive hypertrophic remodeling and dysfunction. Proteasome-mediated hyperpermeability of LEC junctions plays a predominant role in the development of cardiac remodeling. Selective stimulation of lymphangiogenesis or inhibition of proteasome activity may be a potential therapeutic option for treating hypertension-induced cardiac remodeling.

Erratum: CDC20 regulates cardiac hypertrophy via targeting LC3-dependent autophagy: Erratum.

[This corrects the article DOI: 10.7150/thno.27706.].

VEGF-C/VEGFR-3 axis protects against pressure-overload induced cardiac dysfunction through regulation of lymphangiogenesis.

Prolonged pressure overload triggers cardiac hypertrophy and frequently leads to heart failure (HF). Vascular endothelial growth factor-C (VEGF-C) and its receptor VEGFR-3 are components of the central pathway for lymphatic vessel growth (also known as lymphangiogenesis), which has crucial functions in the maintenance of tissue fluid balance and myocardial function after ischemic injury. However, the roles of this pathway in the development of cardiac hypertrophy and dysfunction during pressure overload remain largely unknown. Eight- to 10-week-old male wild-type (WT) mice, VEGFR-3 knockdown (VEGFR-3f/- ) mice, and their WT littermates (VEGFR-3f/f ) were subjected to pressure overload induced by transverse aortic constriction (TAC) for 1-6 weeks. We found that cardiac lymphangiogenesis and the protein expression of VEGF-C and VEGFR-3 were upregulated in the early stage of cardiac hypertrophy but were markedly reduced in failing hearts. Moreover, TAC for 6 weeks significantly reduced cardiac lymphangiogenesis by inhibiting activation of VEGFR-3-mediated signals (AKT/ERK1/2, calcineurin A/NFATc1/FOXc2, and CX43), leading to increased cardiac edema, hypertrophy, fibrosis, apoptosis, inflammation, and dysfunction. These effects were further aggravated in VEGFR-3f/- mice and were dose-dependently attenuated by delivery of recombinant VEGF-C156S in WT mice. VEGF-C156s administration also reversed pre-established cardiac dysfunction induced by sustained pressure overload. Thus, these results demonstrate, for the first time, that activation of the VEGF-C-VEGFR-3 axis exerts a protective effect during the transition from cardiac hypertrophy to HF and highlight selective stimulation of cardiac lymphangiogenesis as a potential new therapeutic approach for hypertrophic heart diseases.

SOCS3 Negatively Regulates Cardiac Hypertrophy via Targeting GRP78-Mediated ER Stress During Pressure Overload.

Pressure overload-induced hypertrophic remodeling is a critical pathological process leading to heart failure (HF). Suppressor of cytokine signaling-3 (SOCS3) has been demonstrated to protect against cardiac hypertrophy and dysfunction, but its mechanisms are largely unknown. Using primary cardiomyocytes and cardiac-specific SOCS3 knockout (SOCS3cko) or overexpression mice, we demonstrated that modulation of SOCS3 level influenced cardiomyocyte hypertrophy, apoptosis and cardiac dysfunction induced by hypertrophic stimuli. We found that glucose regulatory protein 78 (GRP78) was a direct target of SOCS3, and that overexpression of SOCS3 inhibited cardiomyocyte hypertrophy and apoptosis through promoting proteasomal degradation of GRP78, thereby inhibiting activation of endoplasmic reticulum (ER) stress and mitophagy in the heart. Thus, our results uncover SOCS3-GRP78-mediated ER stress as a novel mechanism in the transition from cardiac hypertrophy to HF induced by sustained pressure overload, and suggest that modulating this pathway may provide a new therapeutic approach for hypertrophic heart diseases.

Deficiency of LMP10 Attenuates Diet-Induced Atherosclerosis by Inhibiting Macrophage Polarization and Inflammation in Apolipoprotein E Deficient Mice.

Macrophage polarization and inflammation are key factors for the onset and progression of atherosclerosis. The immunoproteasome complex consists of three inducible catalytic subunits (LMP2, LMP10, and LMP7) that play a critical role in the regulation of these risk factors. We recently demonstrated that the LMP7 subunit promotes diet-induced atherosclerosis via inhibition of MERTK-mediated efferocytosis. Here, we explored the role of another subunit of LMP10 in the disease process, using ApoE knockout (ko) mice fed on an atherogenic diet (ATD) containing 0.5% cholesterol and 20% fat for 8 weeks as an in vivo atherosclerosis model. We observed that ATD significantly upregulated LMP10 expression in aortic lesions, which were primarily co-localized with plaque macrophages. Conversely, deletion of LMP10 markedly attenuated atherosclerotic lesion area, CD68+ macrophage accumulation, and necrotic core expansion in the plaques, but did not change plasma metabolic parameters, lesional SM22α+ smooth muscle cells, or collagen content. Myeloid-specific deletion of LMP10 by bone marrow transplantation resulted in similar phenotypes. Furthermore, deletion of LMP10 remarkably reduced aortic macrophage infiltration and increased M2/M1 ratio, accompanied by decreased expression of pro-inflammatory M1 cytokines (MCP-1, IL-1, and IL-6) and increased expression of anti-inflammatory M2 cytokines (IL-4 and IL-10). In addition, we confirmed in cultured macrophages that LMP10 deletion blunted macrophage polarization and inflammation during ox-LDL-induced foam cell formation in vitro, which was associated with decreased IκBα degradation and NF-κB activation. Our results show that the immunoproteasome subunit LMP10 promoted diet-induced atherosclerosis in ApoE ko mice possibly through regulation of NF-κB-mediated macrophage polarization and inflammation. Targeting LMP10 may represent a new therapeutic approach for atherosclerosis.

Angiotensin II Stimulates the Proliferation and Migration of Lymphatic Endothelial Cells Through Angiotensin Type 1 Receptors.

BACKGROUND/AIM: The proliferation and migration of lymphatic endothelial cells (LECs) is essential for lymphatic vessel growth (also known as lymphangiogenesis), which plays a crucial role in regulating the tissue fluid balance and immune cell trafficking under physiological and pathological conditions. Several growth factors, such as VEGF-C, can stimulate lymphangiogenesis. However, the effects of angiotensin II (Ang II) on the proliferation and migration of mouse LECs and the underlying potential mechanisms remain unknown. METHODS: Wild-type mice were infused with Ang II (1,000 ng/kg/min) for 1-2 weeks. Murine LECs were stimulated with Ang II (500 nM) or saline for 12-48 h. Cell proliferation was determined with 5-bromo-2-deoxyuridine (BrdU) incorporation assays, while cell migration was assessed by scratch wound healing and transwell chamber assays. The gene expression profiles were obtained by time series microarray and real-time PCR analyses. RESULTS: Ang II treatment significantly induced lymphangiogenesis in the hearts of mice and the proliferation and migration of cultured LECs in a time-dependent manner. This effect was completely blocked by losartan, an angiotensin II type 1 receptor (AT1R) antagonist. The microarray results identified 1,385 differentially expressed genes (DEGs) at one or more time points in the Ang II-treated cells compared with the control saline-treated cells. These DEGs were primarily involved in biological processes and pathways, including sensory perception of smell, the G protein coupled receptor signaling pathway, cell adhesion, olfactory transduction, Jak-STAT, alcoholism, RIG-I-like receptor and ECM-receptor interaction. Furthermore, these DEGs were classified into 16 clusters, 7 of which (Nos. 13, 2, 8, 15, 7, 3, and 12, containing 586 genes) were statistically significant. Importantly, the Ang II-induced alterations the expression of lymphangiogenesis-related genes were reversed by losartan. CONCLUSION: The results of the present indicate that Ang II can directly regulate the proliferation and migration of LECs through AT1R in vivo and in vitro, which may provide new potential treatments for Ang II-induced hypertension and cardiac remodeling.

Blockade of intercellular adhesion molecule-1 prevents angiotensin II-induced hypertension and vascular dysfunction.

Monocyte and adhesion infiltration into the arterial subendothelium are initial steps in hypertension development. The endothelial intercellular adhesion molecule-1 (ICAM-1) has been implicated in the recruitment and adhesion of leukocytes in several cardiac diseases. However, the role of ICAM-1 in angiotensin II (Ang II)-induced hypertension development remains unknown. Hypertension was induced by administering an infusion of Ang II (1000 ng/kg/min) to wild-type (WT) mice treated with an IgG control or ICAM-1 neutralizing antibody (1 and 2 mg/mouse/day, respectively). Blood pressure was determined using the tail-cuff system. Vascular remodeling was assessed by performing a histological examination. Inflammation and reactive oxygen species (ROS) levels were determined by using immunostaining. Vascular dysfunction was assessed by aortic ring assay. The expression of fibrotic markers, cytokines and NOX was evaluated by quantitative real-time PCR analysis. Our results demonstrate that Ang II infusion markedly increased the ICAM-1 level in the aorta. Blocking ICAM-1 with a neutralizing antibody significantly attenuated Ang II-induced arterial hypertension, vascular hypertrophy, fibrosis, macrophage infiltration, and ROS production and improved vascular relaxation. In conclusion, ICAM-1-mediated monocyte adhesion and migration play a critical role in Ang II-induced arterial hypertension and vascular dysfunction. ICAM-1 inhibitors may represent a new therapeutic strategy for the treatment of this disease.

Ablation of Immunoproteasome ß5i Subunit Suppresses Hypertensive Retinopathy by Blocking ATRAP Degradation in Mice.

Inflammation is associated with retinal diseases. Our recent data demonstrate that immunoproteasome catalytic subunit ß2i contributes to angiotensin II (Ang II)-induced retinopathy in mice. Here, we investigated the role of another catalytic subunit ß5i in regulating retinopathy and its underlying mechanisms. We induced a murine model of retinopathy by infusing Ang II (3,000 ng/kg/min) for 3 weeks into wild-type (WT) mice, ß5i-knockout (KO) mice, or WT mice injected with either adenovirus-expressing ß5i (Ad-ß5i) or angiotensin II type 1 receptor (AT1R)-associated protein (Ad-ATRAP), which inhibits AT1R. The ß5i expression and chymotrypsin-like activity were most significantly elevated in Ang II-infused retinas and serum from patients with hypertensive retinopathy. Moreover, Ang II infusion-induced retinopathy was markedly attenuated in ß5i-KO mice but aggravated in Ad-ß5i-injected mice. Accordingly, ß5i KO markedly restored Ang II-induced downregulation of ATRAP and activation of AT1R downstream mediators, which was further enhanced in Ad-ß5i-injected mice. Interestingly, overexpression of ATRAP significantly abrogated Ang II-induced retinopathy in Ad-ß5i-injected mice. This study found that ß5i promoted Ang II-induced retinopathy by promoting ATRAP degradation and activation of AT1R-mediated signals.