Effects of early-life exposure to angiotensinⅡ type 1 receptor autoantibody on lipid metabolism in offspring rats / 中华围产医学杂志

Objective:To investigate the effects of early-life (intrauterine and breastfeeding period) exposure to angiotensin Ⅱ type 1 receptor autoantibody (AT 1-AA) on lipid metabolism in offspring rats. Methods:Thirty-two AT 1-AA negative healthy nonpregnant specific pathogen free female Sprague Dawley rats weighing 150-170 g were randomly divided into two groups. Those in the immune group ( n=16) were subcutaneously injected with the mixture of an equal volume of Freund's adjuvant and the second extracellular loop of human-derived angiotensin Ⅱ receptor type 1 (AT1R-ECⅡ) repeatedly to establish the AT 1-AA-positive rat model by active immunization and those in the control group ( n=16) with normal saline solution. Before each immunization, blood samples were collected from the tail of rats to detect serum AT 1-AA levels of those rats in both groups, and the AT 1-AA-positive rat model was successfully established when the serum AT 1-AA was positive and its level reached a plateau. After eight weeks of immunization, the female rats in the two groups were mated with healthy AT 1-AA-negative male rats to conceive. Serum samples were collected from the maternal and offspring rats at the gestation of 18 days (G18), postnatal 21 days (P21), and from the normally fed offspring rats from the time of weaning to 12 weeks old (W12). Active immunization was not performed on the offspring throughout the experiment. The serum AT 1-AA levels of maternal and offspring rats were determined by enzyme-linked immunosorbent assay, and serum AT1-AA was positive when the ratio of AT1-AA level of the immune group over the control group ≥2.1. The blood lipid levels of maternal and offspring rats were measured by an automatic biochemical analyzer. Serum AT 1-AA levels, total cholesterol (TC), high-density lipoprotein-cholesterol [instead of high-density lipoprotein (HDL)], low-density lipoprotein-cholesterol, and free fatty acid levels of the offspring and maternal rats were determined for correlation analysis. Two independent sample t-test, linear regression analysis, and analysis of variance were adopted for statistical analysis. Results:(1) The serum levels of AT 1-AA in maternal rats at G18 and P21 in the immune group were significantly higher than those in the control group (G18: 1.170±0.190 vs 0.114±0.016, t=14.64; P21: 0.988±0.283 vs 0.084±0.006, t=9.57; both P<0.001). (2) The serum levels of AT 1-AA in the offspring at G18 and P21 in the immune group were significantly higher than those in the control group (offspring at G18: 0.948±0.220 vs 0.105±0.010, t=10.10; male offspring at P21: 0.758±0.273 vs 0.080±0.002, t=7.46; female offspring at P21: 0.774±0.274 vs 0.084±0.005, t=7.55; all P<0.001), which showed a positive correlation with those in maternal rats at the same period (offspring at G18: R=0.78; male offspring at P21: R=0.82; female offspring at P21: R=0.82; all P<0.05). However, there was no significant difference in the serum AT 1-AA level in offspring at W12 between the immune and control group ( P>0.05). (3) The serum levels of TC at G18 and P21, and HDL at P21 in maternal rats in the immune group were all higher than those in the control group [TC at G18: (2.36±0.32) vs (1.95±0.24) mmol/L, t=2.70; P21: (2.82±0.50) vs (2.18±0.26) mmol/L, t=3.41; HDL at P21: (1.94±0.33) vs (1.57±0.23) mmol/L, t=2.80; all P<0.05]. (4) Compared with the offspring in the control group, there was no significant change in lipid metabolism at G18 and W12 in the offspring in the immune group (both P>0.05). The serum levels of TC and HDL in male and female offspring at P21 in the immune group were higher than their counterparts in the control[TC in male offspring: (2.38±0.52) vs (1.83±0.30) mmol/L, t=2.73; HDL in male offspring: (1.44±0.32) vs (1.07±0.18) mmol/L, t=2.98; TC in female offspring: (2.50±0.72) vs (1.70±0.26) mmol/L, t=3.16; HDL in female offspring: (1.41±0.33) vs (1.00±0.14) mmol/L, t=3.41; all P<0.05]. (5) The serum levels of TC and HDL in male and female offspring at P21 in the immune group showed no correlation with those in maternal rats at P21 (all R<0.5, all P>0.05). The serum levels of HDL in male and female offspring at P21 in the immune group had a positive correlation with their own serum TC levels (male offspring: R=0.98; female offspring: R=0.97; both P<0.001) and also with their own serum AT 1-AA levels (male offspring: R=0.74, P=0.023; female offspring: R=0.91, P=0.001). The serum levels of TC in male and female offspring at P21 in the immune group had a positive correlation with their serum AT 1-AA levels (male offspring: R=0.72, P=0.030; female offspring: R=0.90, P=0.001). Conclusion:The early-life exposure to AT 1-AA may cause abnormal expression of TC and HDL in offspring rats.

Impaired angiotensin II type 1 receptor signaling contributes to sepsis-induced acute kidney injury.

In sepsis-induced acute kidney injury, kidney blood flow may increase despite decreased glomerular filtration. Normally, angiotensin-II reduces kidney blood flow to maintain filtration. We hypothesized that sepsis reduces angiotensin type-1 receptor (AT1R) expression to account for this observation and tested this hypothesis in a patient case-control study and studies in mice. Seventy-three mice underwent cecal ligation and puncture (a sepsis model) or sham operation. Additionally, 94 septic mice received losartan (selective AT1R antagonist), angiotensin II without or with losartan, or vehicle. Cumulative urine output, kidney blood flow, blood urea nitrogen, and creatinine were measured. AT1R expression was assessed using ELISA, qPCR, and immunofluorescence. A blinded pathologist evaluated tissue for ischemic injury. AT1R expression was compared in autopsy tissue from seven patients with sepsis to that of the non-involved portion of kidney from ten individuals with kidney cancer and three non-infected but critically ill patients. By six hours post ligation/puncture, kidney blood flow doubled, blood urea nitrogen rose, and urine output fell. Concurrently, AT1R expression significantly fell 2-fold in arterioles and the macula densa. Creatinine significantly rose by 24 hours and sham operation did not alter measurements. Losartan significantly exacerbated ligation/puncture-induced changes in kidney blood flow, blood urea nitrogen, creatinine, and urine output. There was no histologic evidence of cortical ischemia. Significantly, angiotensin II prevented changes in kidney blood flow, creatinine, and urine output compared to vehicle. Co-administering losartan with angiotensin-II reversed this protection. Relative to both controls, patients with sepsis had low AT1R expression in arterioles and macula densa. Thus, murine cecal ligation/puncture and clinical sepsis decrease renal AT1R expression. Angiotensin II prevents functional changes while AT1R-blockade exacerbates them independent of ischemia in mice.

Relationship between edaravone-induced inhibition of pressure overload-induced myocardial remodeling and AT1R/MAPKs/StAR signaling pathway in rats / 中华麻醉学杂志

Objective:To evaluate the relationship between edaravone-induced inhibition of pressure overload-induced myocardial remodeling and angiotensin Ⅱ type 1 receptor (AT1R)/mitogen activated protein kinases (MAPKs)/steroidogenic acute regulatory protein (StAR) signaling pathway in rats.Methods:Thirty-six clean-grade healthy male Sprague-Dawley rats, aged 2 months, weighing 200-220 g, were divided into 3 groups ( n=12 each) using a random number table method: sham operation group (S group), pressure overload group (POL group) and edaravone group (E group). The cardiac pressure overload was induced by ligation of thoracic aorta for 8 weeks.After the model preparation, 0.9% sodium chloride 10 ml/kg was intraperitoneally injected daily in group POL, and edaravone 10 mg/kg was given instead in group E for 8 consecutive weeks.After the model was successfully established, the left ventricular ejection fraction (EF) and ventricular shortening fraction (FS) were measured by two-dimensional ultrasound.The animals were sacrificed by bloodletting, and the heart weight/body weight ratio (HW/BW ratio) was calculated.Myocardial tissues were obtained for determination of the cross-sectional area (MSA) after HE staining, the collagen volume fraction (CVF) (using Masson′s staining), the expression of AT1R and StAR (by immunohistochemistry), extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 MAPK phosphorylation levels (p-ERK1/2/ERK1/2 ratio and p-p38 MAPK/p38 MAPK ratio) (by Western blot) and the aldosterone content (by enzyme-linked immunosorbent assay). Results:Compared with group S, the HW/BW ratio, MSA and CVF were significantly increased, EF and FS were decreased, AT1R and StAR expression was up-regulated, and p-ERK1/2/ERK1/2 ratio, p-p38 MAPK/p38 MAPK ratio and aldosterone content were increased in group POL ( P<0.05). Compared with POL group, the HW/BW ratio, MSA and CVF were significantly decreased, EF and FS were increased, AT1R and StAR expression was down-regulated, and p-ERK1/2/ERK1/2 ratio, p-p38 MAPK/p38 MAPK ratio and aldosterone content were decreased in group E ( P<0.05). Conclusion:The mechanism of edaravone-induced inhibition of pressure overload-induced myocardial remodeling is probably associated with inhibiting the activation of AT1R/MAPKs/StAR signaling pathway in rats.

ACE (Angiotensin-Converting Enzyme) Inhibition Reverses Vasoconstriction and Impaired Dilation of Pial Collaterals in Chronic Hypertension.

Leptomeningeal anastomoses (LMAs) are pial collaterals that perfuse the penumbra and important for stroke outcome. We previously showed LMAs from SHRs (spontaneously hypertensive rats) were vasoconstricted compared with normotensive Wistar rats. Here, we investigated mechanisms by which hypertension causes LMA vasoconstriction. SHRs were treated with the ACE (angiotensin-converting enzyme) inhibitor captopril, an Ang II (angiotensin II)-independent antihypertensive agent hydralazine, or vehicle for 5 weeks in drinking water (n=8/group). A group of Wistar rats (n=8) had regular drinking water served as controls. Blood pressure was measured twice weekly by tail-cuff. LMAs were isolated and studied under pressurized conditions. Vasoreactivity of LMAs, including myogenic responses, reactivity to Rho-kinase inhibitor Y-27632, and nitric oxide were measured. Both captopril and hydralazine lowered blood pressure in SHRs similar to Wistar. However, only captopril normalized LMA increased tone compared with untreated SHRs (15±2% versus 50±3%; P<0.01) that was similar to Wistar (16±2%) but not hydralazine (38±6%; P>0.05). Vasodilatory response of LMAs to Y-27632 was impaired in SHRs compared with Wistar (28±3% versus 81±4%; P<0.01) that was restored by captopril (84±5%; P<0.01) and partially hydralazine (59±4%). LMAs from all groups constricted similarly to NOS (NO synthase) inhibition; however, the vasodilatory response of LMAs to the nitric oxide donor sodium nitroprusside was impaired in SHRs compared with Wistar rats (29±4% versus 80±2%; P<0.01) that was restored by captopril (84±4%; P<0.01), not hydralazine (38±8%; P>0.05). These results suggest that ACE inhibition during chronic hypertension reversed vascular dysfunction and hyperconstriction of LMAs that could improve stroke outcome by increasing collateral perfusion.

Brain renin-angiotensin system: a potential therapeutic target for ischemic stroke / 国际脑血管病杂志

Brain renin-angiotensin system (RAS) is closely associated with many pathophysiological processes of cardiocerebrovascular diseases,including stroke.The activation of the different components in RAS will produce specific biological effects.This article reviews the roles of brain RAS in the pathophysiological processes of ischemic stroke,especially the neuroprotective effect of ACE2/Ang-(1-7)/Mas axis.

Progress of the relationship between angiotensin Ⅱ and its type 1 receptor and some malignant tumors / 肿瘤研究与临床

Angiotensin Ⅱ (Ang Ⅱ) is the main effector of the renin-angiotensin system (RAS). As a major regulator of blood pressure and cardiovascular homeostasis, Ang Ⅱis involved in the regulation of cell growth, proliferation and apoptosis. Ang Ⅱtype 1 receptor (AGTR1) is the important part of the RAS by mediating most of the Ang Ⅱ actions. Recently evidence suggested that AGTR1 correlated with tumor angiogenesis and poor patient outcome in cancer. Therefore, AGTR1 blockers have the potential to suppress the tumor angiogenesis and metastasis. This article intents to summarize the progression of the relationship between AngⅡ,AGTR1 and some malignant tumors.

The expressions and clinical relevance of angiotensin-receptor-1 and hypoxia-inducible factor-1α in glomerulus and juxtaglomerular apparatus of patients with lupus nephritis / 中华风湿病学杂志

Objective To detect the expressions of angiotensin-receptor-1 (AT1R) and hypoxia-inducible factor (HIF)-1αin glomeruli and juxtaglomerular apparatus of different types of lupus nephritis (LN) patients, and analyze the correlation between them with systemic lupus erythematosus disease activity index (SLEDAI) complement 3, serum creatinine and 24-hour proteinuria in order to explore the role of the two factors in the pathogenesis of lupus nephritis (LN). Methods Between May 2010 and April 2016, a total of 90 patients with LN and 8 healthy controls were selected from Department of Rheumatology, Qujing Affiliated Hospital of Kunming Medical University and the First Affiliated Hospital of Kunming Medical University. The expressions of AT1R and HIF-1αin renal biopsy specimens were measured by streptavidin-perosidase (SP) of immunohistochemical stains. Pathological graphic analysis system was used for semi-quantitative estimate. Levels of SLEDAI, C3, serum creatinin and 24-hour proteinuria were also detected. Finally the relationshipbetween the two factors with clinical data was analyzed. The ANOVA test was used for intergroup comparison, and SNK-q test was used for the two groups comparison. Pearson's analysis was used for correlation analysis. Results The AT1R [(10.55 ±0.31)% vs (7.04 ±0.11)%] and HIF-1α [(10.51 ±0.52)% vs (8.96 ±0.31)%] in the glomeruli of typeⅠLN was significantly higher than healthy controls(all P<0.05). In the early phase of LN, RAS was activated and tissues were ischemic and hypoxic. The highest expression of AT1R (18.22 ± 2.11)% and HIF-1α (19.48 ±0.61)% in glomeruli was found in type Ⅳ LN, especially in juxtaglomerular apparatus, AT1R (19.98 ±0.21)% and HIF-1α(24.90 ±0.70)%. AT1R was positively correlated with HIF-1αin the glomer-ulus (r=0.949, P<0.01) and juxtaglomerular apparatus (r=0.762, P<0.05). AT1R and HIF-1αin juxtaglomerular apparatus was positively correlated with 24-hour proteinuria (r=0.756, P<0.05 and r=0.802, P<0.05). Conclusion High expressions of AT1R and HIF-1α have been shown in active LN biopsies. It proves that RAS is activated by ischemia and hypoxia, then it up-regulates HIF-1α expression. Our results suggest that the two factors may be associated with disease activity of LN.

The expressions and clinical relevance of angiotensin-receptor-1 and hypoxia-inducible factor-1α in glomerulus and juxtaglomerular apparatus of patients with lupus nephritis / 中华风湿病学杂志

Objective To detect the expressions of angiotensin-receptor-1 (AT1R) and hypoxia-inducible factor (HIF)-1αin glomeruli and juxtaglomerular apparatus of different types of lupus nephritis (LN) patients, and analyze the correlation between them with systemic lupus erythematosus disease activity index (SLEDAI) complement 3, serum creatinine and 24-hour proteinuria in order to explore the role of the two factors in the pathogenesis of lupus nephritis (LN). Methods Between May 2010 and April 2016, a total of 90 patients with LN and 8 healthy controls were selected from Department of Rheumatology, Qujing Affiliated Hospital of Kunming Medical University and the First Affiliated Hospital of Kunming Medical University. The expressions of AT1R and HIF-1αin renal biopsy specimens were measured by streptavidin-perosidase (SP) of immunohistochemical stains. Pathological graphic analysis system was used for semi-quantitative estimate. Levels of SLEDAI, C3, serum creatinin and 24-hour proteinuria were also detected. Finally the relationshipbetween the two factors with clinical data was analyzed. The ANOVA test was used for intergroup comparison, and SNK-q test was used for the two groups comparison. Pearson's analysis was used for correlation analysis. Results The AT1R [(10.55 ±0.31)% vs (7.04 ±0.11)%] and HIF-1α [(10.51 ±0.52)% vs (8.96 ±0.31)%] in the glomeruli of typeⅠLN was significantly higher than healthy controls(all P<0.05). In the early phase of LN, RAS was activated and tissues were ischemic and hypoxic. The highest expression of AT1R (18.22 ± 2.11)% and HIF-1α (19.48 ±0.61)% in glomeruli was found in type Ⅳ LN, especially in juxtaglomerular apparatus, AT1R (19.98 ±0.21)% and HIF-1α(24.90 ±0.70)%. AT1R was positively correlated with HIF-1αin the glomer-ulus (r=0.949, P<0.01) and juxtaglomerular apparatus (r=0.762, P<0.05). AT1R and HIF-1αin juxtaglomerular apparatus was positively correlated with 24-hour proteinuria (r=0.756, P<0.05 and r=0.802, P<0.05). Conclusion High expressions of AT1R and HIF-1α have been shown in active LN biopsies. It proves that RAS is activated by ischemia and hypoxia, then it up-regulates HIF-1α expression. Our results suggest that the two factors may be associated with disease activity of LN.

Novel retro-inverso peptide inhibitor reverses angiotensin receptor autoantibody-induced hypertension in the rabbit.

Activating autoantibodies to the angiotensin II type 1 receptor (AT1R) have been implicated in hypertensive disorders. We investigated whether AT1R antibodies produced in immunized rabbits will activate AT1R and contribute to hypertension by a direct contractile effect on the vasculature and whether they can be blocked by a novel decoy peptide. A multiple antigenic peptide containing the AT1R epitope AFHYESQ, which is the receptor-binding epitope of AT1R-activating autoantibodies, was used to immunize 6 rabbits. AT1R antibody activity was analyzed in AT1R-transfected cells, and their contractile effects were assayed using isolated perfused rat cremaster resistance arterioles. A retro-inverso D-amino acid epitope-mimetic peptide was tested for AT1R antibody inhibition in vitro and in vivo. All immunized animals produced high AT1R antibody titers and developed elevated blood pressure. No changes in measured blood chemistry values were observed after immunization. Rabbit anti-AT1R sera induced significant AT1R activation in transfected cells and vasoconstriction in the arteriole assay, both of which were blocked by losartan and the retro-inverso D-amino acid peptide. A single intravenous bolus injection of the retro-inverso d-amino acid peptide (1 mg/kg) into immunized rabbits dropped the mean arterial pressure from 122±11 to 82±6 mm Hg. Rabbit anti-AT1R sera partially suppressed angiotensin II-induced contraction of isolated rat cremaster arterioles, and the pressor response to angiotensin II infusion was attenuated in immunized animals. In conclusion, AT1R-activating autoantibodies and the retro-inverso d-amino acid peptide, respectively, have important etiologic and therapeutic implications in hypertensive subjects who harbor these autoantibodies.

Dimorphic effects of transforming growth factor-ß signaling during aortic aneurysm progression in mice suggest a combinatorial therapy for Marfan syndrome.

OBJECTIVE: Studies of mice with mild Marfan syndrome (MFS) have correlated the development of thoracic aortic aneurysm (TAA) with improper stimulation of noncanonical (Erk-mediated) TGFß signaling by the angiotensin type I receptor (AT1r). This correlation was largely based on comparable TAA modifications by either systemic TGFß neutralization or AT1r antagonism. However, subsequent investigations have called into question some key aspects of this mechanism of arterial disease in MFS. To resolve these controversial points, here we made a head-to-head comparison of the therapeutic benefits of TGFß neutralization and AT1r antagonism in mice with progressively severe MFS (Fbn1(mgR/mgR) mice). APPROACH AND RESULTS: Aneurysm growth, media degeneration, aortic levels of phosphorylated Erk and Smad proteins and the average survival of Fbn1(mgR/mgR) mice were compared after a ≈3-month-long treatment with placebo and either the AT1r antagonist losartan or the TGFß-neutralizing antibody 1D11. In contrast to the beneficial effect of losartan, TGFß neutralization either exacerbated or mitigated TAA formation depending on whether treatment was initiated before (postnatal day 16; P16) or after (P45) aneurysm formation, respectively. Biochemical evidence-related aneurysm growth with Erk-mediated AT1r signaling, and medial degeneration with TGFß hyperactivity that was in part AT1r dependent. Importantly, P16-initiated treatment with losartan combined with P45-initiated administration of 1D11 prevented death of Fbn1(mgR/mgR) mice from ruptured TAA. CONCLUSIONS: By demonstrating that promiscuous AT1r and TGFß drive partially overlapping processes of arterial disease in MFS mice, our study argues for a therapeutic strategy against TAA that targets both signaling pathways although sparing the early protective role of TGFß.

Stretch-activation of angiotensin II type 1a receptors contributes to the myogenic response of mouse mesenteric and renal arteries.

RATIONALE: Vascular wall stretch is the major stimulus for the myogenic response of small arteries to pressure. The molecular mechanisms are elusive, but recent findings suggest that G protein-coupled receptors can elicit a stretch response. OBJECTIVE: To determine whether angiotensin II type 1 receptors (AT1R) in vascular smooth muscle cells exert mechanosensitivity and identify the downstream ion channel mediators of myogenic vasoconstriction. METHODS AND RESULTS: We used mice deficient in AT1R signaling molecules and putative ion channel targets, namely AT1R, angiotensinogen, transient receptor potential channel 6 (TRPC6) channels, or several subtypes of the voltage-gated K+ (Kv7) gene family (KCNQ3, 4, or 5). We identified a mechanosensing mechanism in isolated mesenteric arteries and in the renal circulation that relies on coupling of the AT1R subtype a to a Gq/11 protein as a critical event to accomplish the myogenic response. Arterial mechanoactivation occurs after pharmacological block of AT1R and in the absence of angiotensinogen or TRPC6 channels. Activation of AT1R subtype a by osmotically induced membrane stretch suppresses an XE991-sensitive Kv channel current in patch-clamped vascular smooth muscle cells, and similar concentrations of XE991 enhance mesenteric and renal myogenic tone. Although XE991-sensitive KCNQ3, 4, and 5 channels are expressed in vascular smooth muscle cells, XE991-sensitive K+ current and myogenic contractions persist in arteries deficient in these channels. CONCLUSIONS: Our results provide definitive evidence that myogenic responses of mouse mesenteric and renal arteries rely on ligand-independent, mechanoactivation of AT1R subtype a. The AT1R subtype a signal relies on an ion channel distinct from TRPC6 or KCNQ3, 4, or 5 to enact vascular smooth muscle cell activation and elevated vascular resistance.

Effects of cardiac overexpression of the angiotensin II type 2 receptor on remodeling and dysfunction in mice post-myocardial infarction.

The activation of angiotensin II type 2 receptor (AT2R) has been considered cardioprotective. However, there are controversial findings regarding the role of overexpressing AT2R in the heart. Using transgenic mice with different levels of AT2R gene overexpression in the heart (1, 4, or 9 copies of the AT2R transgene: Tg1, Tg4, or Tg9), we studied the effect of AT2R overexpression on left ventricular remodeling and dysfunction post-myocardial infarction (MI). Tg1, Tg4, Tg9, and their wild-type littermates were divided into (1) sham MI, (2) MI plus vehicle, and (3) MI plus AT2R antagonist. Treatments were started 4 weeks after MI and continued for 8 weeks. AT2R protein and mRNA expression in the heart was significantly increased in transgenic mice, and the increase positively correlated with copies of the transgene. AT1R protein and mRNA expression remained unchanged in Tg1 and Tg4 but slightly increased in Tg9 mice. Systolic blood pressure and cardiac phenotypes did not differ among strains under basal conditions. MI caused myocardial hypertrophy, interstitial fibrosis, ventricular dilatation, and dysfunction associated with increased protein expression of Nox2 and transforming growth factor ß1. These pathological responses were diminished in Tg1 and Tg4 mice. Moreover, the protective effects of AT2R were abolished by AT2R antagonist and also absent in Tg9 mice. We thus conclude that whether overexpression of AT2R is beneficial or detrimental to the heart is largely dependent on expression levels and possibly via regulations of Nox2 and transforming growth factor ß1 signaling pathways.

Circulating angiotensin II gains access to the hypothalamus and brain stem during hypertension via breakdown of the blood-brain barrier.

Angiotensin II-mediated vascular brain inflammation emerged as a novel pathophysiological mechanism in neurogenic hypertension. However, the precise underlying mechanisms and functional consequences in relation to blood-brain barrier (BBB) integrity and central angiotensin II actions mediating neurohumoral activation in hypertension are poorly understood. Here, we aimed to determine whether BBB permeability within critical hypothalamic and brain stem regions involved in neurohumoral regulation was altered during hypertension. Using digital imaging quantification after intravascularly injected fluorescent dyes and immunohistochemistry, we found increased BBB permeability, along with altered key BBB protein constituents, in spontaneously hypertensive rats within the hypothalamic paraventricular nucleus, the nucleus of the solitary tract, and the rostral ventrolateral medulla, all critical brain regions known to contribute to neurohumoral activation during hypertension. BBB disruption, including increased permeability and downregulation of constituent proteins, was prevented in spontaneously hypertensive rats treated with the AT1 receptor antagonist losartan, but not with hydralazine, a direct vasodilator. Importantly, we found circulating angiotensin II to extravasate into these brain regions, colocalizing with neurons and microglial cells. Taken together, our studies reveal a novel angiotensin II-mediated feed-forward mechanism during hypertension, by which circulating angiotensin II evokes increased BBB permeability, facilitating in turn its access to critical brain regions known to participate in blood pressure regulation.

Role of GRK4 in the regulation of arterial AT1 receptor in hypertension.

G-protein-coupled receptor kinase 4 (GRK4) gene variants, via impairment of renal dopamine receptor and enhancement of renin-angiotensin system functions, cause sodium retention and increase blood pressure. Whether GRK4 and the angiotensin type 1 receptor (AT(1)R) interact in the aorta is not known. We report that GRK4 is expressed in vascular smooth muscle cells of the aorta. Heterologous expression of the GRK4γ variant 142V in A10 cells increased AT(1)R protein expression and AT(1)R-mediated increase in intracellular calcium concentration. The increase in AT(1)R expression was related to an increase in AT(1)R mRNA expression via the NF-κB pathway. As compared with control, cells expressing GRK4γ 142V had greater NF-κB activity with more NF-κB bound to the AT(1)R promoter. The increased AT(1)R expression in cells expressing GRK4γ 142V was also associated with decreased AT(1)R degradation, which may be ascribed to lower AT(1)R phosphorylation. There was a direct interaction between GRK4γ and AT(1)R that was decreased by GRK4γ 142V. The regulation of AT(1)R expression by GRK4γ 142V in A10 cells was confirmed in GRK4γ 142V transgenic mice; AT(1)R expression was higher in the aorta of GRK4γ 142V transgenic mice than control GRK4γ wild-type mice. Angiotensin II-mediated vasoconstriction of the aorta was also higher in GRK4γ 142V than in wild-type transgenic mice. This study provides a mechanism by which GRK4, via regulation of arterial AT(1)R expression and function, participates in the pathogenesis of conduit vessel abnormalities in hypertension.

Relationship of angiotensin Ⅱ type 1 receptor autoantibody and renal cell apoptosis induced by caspase-12 in diabetic nephropathy rats / 中华肾脏病杂志

Objective To study the relationship of angiotensin Ⅱ type 1 receptor (AT1R) autoantibody (AT1-AA) and renal cell apoptosis induced by caspase-12 in diabetic nephropathy (DN)rats.Methods High-sucrose and high-fat diet and intraperitoneal injection of streptozotocin (35 mg/kg) were utilized to establish DN rat model.Serum AT1-AA was detected by enzyme-linked immunosorbent assay (ELISA) and renal cell apoptosis was detected by TUNEL staining.Furthermore,the mRNA levels of the endoplasmic reticulum stress (ERS) chaperone protein glucose regulated protein 78 (GRP78) and ERS-associated apoptosis protein caspase-12 were measured by real-time quantitative PCR.Additionally,the levels of GRP78 and caspase-12 protein were measured by Western blotting.Results The renal cell apoptosis rate in DN group was increased significantly (P ＜ 0.01),and the renal cells apoptosis rate in AT1-AA positive DN group was higher than that in AT1-AA negative DN group [(20.05±1.71)％ vs (13.24±4.93)％,P ＜ 0.01].The mRNA expressions of GRP78 and caspase-12 in DN group,in comparison to NC group,were increased significantly (P ＜ 0.01),as well as the proteins (P ＜ 0.01).And the expression of these mRNA and proteins had significant increment in AT1-AA positive DN rats when compared with AT1-AA negative DN rats (P ＜ 0.05).Conclusions AT1-AA can induce ERS in the renal tissue of DN rats,and promote renal cell apoptosis likely via the modulation of caspase-12 signaling pathway.

Expression and significance of autoantibodies against angiotensin Ⅱ type 1 receptor in acute coronary syndrome / 中国医师进修杂志

Objective To examine the expression of autoantibodies against angiotensin Ⅱ type 1 receptor (AT1-AAs),monocyte chemoattractant protein-1 (MCP-1) and high-sensitivity C-reactive protein (hs-CRP) in patients of acute coronary syndrome (ACS),and study the role of AT1-AAs in plaque stability and pathogenesis of ACS.Methods Sixty patients with ACS were selected as ACS group,60 patients with stable angina pectoris (SAP) were selected as SAP group,and 60 healthy people were selected as control groups.The epitopes of the second extracellular loop of angiotensin Ⅱ type 1 receptor (165-191) were synthesized and used as antigen to screen the serum autoantibodies by enzyme-linked immunosorbent assay (ELISA).The peripheral blood levels of MCP-1 and hs-CRP were also evaluated.Results The positive rates of AT1-AAs in ACS group,SAP group and control group were 45.0％(27/60),21.7％(13/60) and 5.0％(3/60),respectively.The positive rates of AT1-AAs in ACS group and SAP group were significantly higher than those in control group,the positive rate of AT1-AAs in ACS group was significantly higher than that in SAP group,and there were statistical differences (P ＜ 0.01).The MCP-1 and hs-CRP levels in ACS group and SAP group were significantly higher than those in control group,the MCP-1 and hs-CRP levels in ACS group were significantly higher than those in SAP group,and there were statistical differences (P ＜ 0.01).The MCP-1 and hs-CRP levels in AT1-AAs positive patients in ACS group and SAP group were significantly higher than those in AT1-AAs negative patients,and there were statistical differences (P ＜0.01).Conclusions AT1-AAs may play an important role in the pathogenesis of ACS.Inducing the expression of inflammatory factor through AT1-AAs maybe an important mechanism for plaque instability.

Correlations between AT1R gene polymorphism with AT1R mRNA and protein expression difference in brain tissue after hypertensive cerebral hemorrhage / 重庆医学

Objective To investigate the correlation of angiotensin Ⅱ type 1 receptor (AT1R) gene polymorphism with AT1R expression levels and brain edema after hypertensive intracerebral hemorrhage .Methods 45 operative patients with hypertensive intracerebral hemorrhage in the Affiliated Yongchuan Hospital of Chongqing Medical Univercity from December 2011 to August 2012 were collected as the experimental group and 45 operative patients with refractory epilepsy weres selected as the control group .The venous blood in the two groups were collected for detecting the AT 1R gene polymorphism ;The brain tissue was taken from lesions in operation ,then AT1R mRNA concentration was determined by RT-PCR and the AT1R protein level was determined by Western blot ;Head CT was performed on postoperative 1 ,3 ,5 d;the degree of cerebral edema was reflected by CT value . Results The levels of two kinds of genotype AT1R mRNA in the experimental group had no statistically significant difference(P>0 .05);the operative area CT value of AC genotype was significantly lower than that of AA genotype with statistical difference (P<0 .05);the ATIRmRNA of various genotypes ,protein level and cerebral edema in the control group had no statistical differences . Conclusion The AT 1R gene polymorphism has no obvious correlation with the concentration expression of AT 1R mRNA in the brain tis-sue;there is correlation between AT 1R protein level and AT 1R protein level and the cerebral edema degree in the brain tissue .

Roles of angiotensin Ⅱ receptors in tumor / 国际肿瘤学杂志

Angiotensin (Ang Ⅱ),a main effector peptide of the renin-angiotensin system (RAS),mediates a hormonal action in the maintenance of blood pressure and electrolyte levels,and thus fluid homeostasis.Recent studies have implicated that it correlates with tumor growth,angiogenesis,metastasis and it has drawn more and more attention.Many studies show that Ang Ⅱ-AT1R/AT2R play crucial roles in tumor growth,metastasis,invasion and tumor angiogenesis,which are formed new targets for treating malignant tumors.