Inibição combinada do receptor AT1 e produtos finais de glicação avançada na nefropatia diabética / Combined inhibition of AT1 receptor and advanced glycation end products in diabetic nephropathy

O diabetes mellitus (DM) é um grande problema de saúde pública, que afeta cerca de 463 milhões de pessoas no mundo e pode alcançar 700 milhões de pessoas até 2045. A nefropatia é uma das complicações microvasculares do diabetes e a maior causa de insuficiência renal. Uma vez que a ativação do receptor AT1 pela angiotensina II causa vasoconstrição da artéria aferente, e que o acúmulo de produtos finais de glicação avançada (AGEs) causam glicotoxicidade intracelular de células mesangiais, podocitárias e tubulares, foi avaliado se o tratamento combinado de olmersatana (OLM) e piridoxamina (PYR) é capaz de melhorar a nefropatia diabética quando comparado aos tratamentos isolados. Para isto, o diabetes mellitus experimental foi induzido em 50 camundongos C57BL/6 pela administração de estreptozotocina (50 mg/kg/dia via intraperitoneal por 5 dias). Os animais foram divididos em cinco grupos: controle, diabéticos, diabéticos tratados com OLM (20 mg/Kg/dia), diabéticos tratados com PYR (400 mg/Kg/dia) e diabéticos tratados com OLM e PYR (20 mg/Kg/dia e 400 mg/Kg/dia, respectivamente) Os tratamento durou 16 semanas. Como resultado, os camundongos que receberam STZ desenvolveram hiperglicemia e doença renal, diminuição de peso, poliúria, polidipsia, polifagia, e albuminúria, além de aumento de frutosamina, ferro, uréia e fosfatase alcalina na urina, diminuição da atividade de catalase no rim e aumento de excreção dos AGEs na urina. Histologicamente, houve aumento de área glomerular e do espaço de BowmanO tratamento com OLM atenuou a albuminúria e atenuou o declínio da função renal, uma vez que o OLM melhorou a polidipsia, polifagia, poliúria, marcadores bioquímicos de disfunção renal e parâmetros histológicos, apesar de não apresentar ação sobre a fosfatase alcalina, uréia, ferro, frutosamina e ácido úrico. O tratamento isolado com PYR melhorou a maioria dos parâmetros alterados pela doença, entre eles a ingestão alimentar, ingestão hídrica, volume urinário, creatinina sérica, excreção de albumina na urina, ACR, AGEs no tecido renal e urina, ureia na urina e todos os parâmetros morfológicos analisados, contudo sem efeito sobre a fosfatase alcalina, ferro, frutosamina e ácido úrico. O tratamento combinado (PYR e OLM) melhorou a polifagia, polidipsia e poliúria comparado aos animais diabéticos sem tratamento, entretanto não houve diferença comparado a cada tratamento isolado. Os parâmetros histológicos e bioquímicos (creatinina no soro, albumina na urina, ACR e uréia) também apresentaram melhorara em relação aos animais diabéticos sem tratamento, mas não em relação aos animais em tratamento isolado. Tanto PYR quanto OLM não influenciaram a excreção de AGEs na urina. Esses dados nos levam a concluir que o tratamento combinado não ofereceu efeitos benéficos adicionais quando comparado aos tratamentos isolados, e que o tratamento que mais ofereceu benefícios foi o tratamento isolado com PYR nos parâmetros metabólicos, morfológicos e de função renal. (AU)

Macrophage exosomes transfer angiotensin II type 1 receptor to lung fibroblasts mediating bleomycin-induced pulmonary fibrosis / 中华医学杂志(英文版)

BACKGROUND@#Macrophages are involved in the pathogenesis of idiopathic pulmonary fibrosis, partially by activating lung fibroblasts. However, how macrophages communicate with lung fibroblasts is largely unexplored. Exosomes can mediate intercellular communication, whereas its role in lung fibrogenesis is unclear. Here we aim to investigate whether exosomes can mediate the crosstalk between macrophages and lung fibroblasts and subsequently induce fibrosis.@*METHODS@#In vivo, bleomycin (BLM)-induced lung fibrosis model was established and macrophages infiltration was examined. The effects of GW4869, an exosomes inhibitor, on lung fibrosis were assessed. Moreover, macrophage exosomes were injected into mice to observe its pro-fibrotic effects. In vitro, exosomes derived from angiotensin II (Ang II)-stimulated macrophages were collected. Then, lung fibroblasts were treated with the exosomes. Twenty-four hours later, protein levels of α-collagen I, angiotensin II type 1 receptor (AT1R), transforming growth factor-β (TGF-β), and phospho-Smad2/3 (p-Smad2/3) in lung fibroblasts were examined. The Student's t test or analysis of variance were used for statistical analysis.@*RESULTS@#In vivo, BLM-treated mice showed enhanced infiltration of macrophages, increased fibrotic alterations, and higher levels of Ang II and AT1R. GW4869 attenuated BLM-induced pulmonary fibrosis. Mice with exosomes injection showed fibrotic features with higher levels of Ang II and AT1R, which was reversed by irbesartan. In vitro, we found that macrophages secreted a great number of exosomes. The exosomes were taken by fibroblasts and resulted in higher levels of AT1R (0.22 ± 0.02 vs. 0.07 ± 0.02, t = 8.66, P = 0.001), TGF-β (0.54 ± 0.05 vs. 0.09 ± 0.06, t = 10.00, P < 0.001), p-Smad2/3 (0.58 ± 0.06 vs. 0.07 ± 0.03, t = 12.86, P < 0.001) and α-collagen I (0.27 ± 0.02 vs. 0.16 ± 0.01, t = 7.01, P = 0.002), and increased Ang II secretion (62.27 ± 7.32 vs. 9.56 ± 1.68, t = 12.16, P < 0.001). Interestingly, Ang II increased the number of macrophage exosomes, and the protein levels of Alix (1.45 ± 0.15 vs. 1.00 ± 0.10, t = 4.32, P = 0.012), AT1R (4.05 ± 0.64 vs. 1.00 ± 0.09, t = 8.17, P = 0.001), and glyceraldehyde-3-phosphate dehydrogenase (2.13 ± 0.36 vs. 1.00 ± 0.10, t = 5.28, P = 0.006) were increased in exosomes secreted by the same number of macrophages, indicating a positive loop between Ang II and exosomes production.@*CONCLUSIONS@#Exosomes mediate intercellular communication between macrophages and fibroblasts plays an important role in BLM-induced pulmonary fibrosis.

Planejamento e desenvolvimento de ligantes não peptídicos com atividade agonista enviesada no receptor de angiotensina II tipo 1 empregando-se técnicas de modelagem molecular e ensaios in vitro / Drug design of non-peptidic biased agonists for angiotensin II type 1 receptor using molecular modeling techniques and in vitro tests

A insuficiência cardíaca (IC) é uma síndrome de elevada morbimortalidade, correspondendo a um grave problema de saúde pública. Uma das abordagens terapêuticas para IC consiste no uso de antagonistas do receptor de angiotensina II do tipo 1 (AT1R), conhecidos como sartanas. Estudos apontam que uma nova classe de compostos, os agonistas enviesados, é capaz de induzir a sinalização da via da ß-arrestina sem ativação da via da proteína G. Essa seletividade funcional é particularmente interessante, pois a via dependente da proteína G é responsável pelo aumento da pressão arterial, morte celular e fibrose tecidual, levando a hipertrofia cardíaca e progressão da IC. No entanto, a via da ß-arrestina está associada com renovação celular e aumento do inotropismo. Além disso, estudos in vivo sugerem que agonistas enviesados poderiam corresponder a uma terapia superior à dos antagonistas convencionais, que bloqueiam ambas as vias. Apesar do potencial terapêutico, esses compostos possuem estrutura peptídica e, por isso, tem sua administração restrita à via intravenosa. A resolução da estrutura cristalográfica do AT1R permitiu estudos de modelagem molecular mais acurados. Tendo isso em mente, nesse trabalho foram propostos agonistas enviesados de natureza não peptídica para o AT1R por meio de técnicas de modelagem molecular e validação das hipóteses levantadas por ensaios in vitro. Foram realizados estudos de dinâmica molecular com o AT1R (PDB ID: 4YAY) em uma bicamada lipídica e ensaios de ancoramento molecular da angiotensina II (AngII) e do ligante enviesado TRV027. As poses de ancoramento molecular selecionadas foram utilizadas em dinâmicas de complexo, que revelaram diferenças entre os sistemas apo (sem nenhum ligante) e holo (com o ligante no sitio de ligação). Nossos resultados sugerem que o TRV027 induz um padrão exclusivo de ligações de hidrogênio e de estrutura secundária, enquanto que a AngII afeta os resíduos do bolso hidrofóbico do sitio de ligação, principalmente a conformação do Trp2536.48. Com base nas simulações, três farmacóforos foram criados e utilizados de maneira complementar em triagens virtuais na base de dados ZINC15, resultando na seleção de cinco compostos. Um desses compostos apresentou afinidade pelo receptor AT1R e, ainda que estudos complementares de ativação de vias especificas sejam necessários para que o composto possa ser classificado como agonista enviesado, já se constitui em molécula potencialmente promissora. Além disso, esses estudos permitiram a proposição de estruturas inéditas que podem vir a ser hits no processo de desenvolvimento de agonistas enviesados para AT1R. Portanto, como continuidade desse trabalho, essas moléculas serão sintetizadas e investigadas quanto à possível interação com o receptor.

Heart Failure (HF) is a common syndrome with high morbimortality, being considered a serious public health problem. One of the therapeutic approaches for HF consists in the use of the sartan class, which are angiotensin II type 1 receptor (AT1R) antagonists. Recent studies have shown that a new class of compounds, known as biased agonists, is able to induce signaling via ß-arrestin without G-protein activation. This functional selectivity is particularly interesting since G-protein dependent signaling is responsible for cell death and cardiac tissue fibrosis, which leads to cardiac muscle hypertophy and HF progression. On the other hand, ß-arrestin signaling is associated with cellular renewal and increased inotropism. In vivo studies suggests that biased agonists could correspond to a superior therapy over conventional angiotensin II type 1 receptor antagonists, which blocks cell signaling as a whole, however their peptidic structure restricts their use to intravenous administration. Moreover, the AT1R crystal structure determination holds great promise for more accurate molecular modeling studies. With that being said, the aim of this work was to plan and develop new non-peptidic biased agonists for ATR1 employing molecular modeling techniques and in vitro tests for hypothesis validation. Molecular dynamics (MD) simulations of the refined AT1R crystal (PDB ID: 4YAY) embedded in a lipid bilayer and molecular docking studies with angiotensin II (AngII) and TRV027 (biased agonist) were conducted. Selected docking poses from both ligands underwent complex MD simulations revealing differences between apo (ligand free) and holo (ligand in the binding site) systems. Our results suggest that TRV027 induces an exclusive hydrogen bond and secondary structure pattern, while AngII affects the hydrophobic pocket conformation, mainly Trp253. Based on the simulations, three pharmacophore models were created and used in virtual screenings in the ZINC15 database, resulting in the selection of five compounds that were tested in vitro. One of the compounds displayed affinity for AT1R and is a promising molecule. Nonetheless, it needs further pathway activation characterization in order to be a classified as a biased agonist. Furthermore, these results have contributed significantly for the proposition of new structures that could be hits with biased agonist activity for AT1R. Thus, for future works, we point out the necessity for synthesis and characterization of this new compounds

Telmisartan Inhibits Nitric Oxide Production and Vessel Relaxation via Protein Phosphatase 2A-mediated Endothelial NO Synthase-Ser¹¹⁷⁹ Dephosphorylation

BACKGROUND: Apart from its blood pressure-lowering effect by blocking the renin-angiotensin-aldosterone system, telmisartan, an angiotensin II type 1 receptor blocker (ARB), exhibits various ancillary effects including cardiovascular protective effects in vitro. Nonetheless, the protective effects of telmisartan in cerebrocardiovascular diseases are somewhat variable in large-scale clinical trials. Dysregulation of endothelial nitric oxide (NO) synthase (eNOS)-derived NO contributes to the developments of various vascular diseases. Nevertheless, the direct effects of telmisartan on endothelial functions including NO production and vessel relaxation, and its action mechanism have not been fully elucidated. Here, we investigated the mechanism by which telmisartan regulates NO production and vessel relaxation in vitro and in vivo. METHODS: We measured nitrite levels in culture medium and mouse serum, and performed inhibitor studies and western blot analyses using bovine aortic endothelial cells (BAECs) and a hyperglycemic mouse model. To assess vessel reactivity, we performed acetylcholine (ACh)-induced vessel relaxation assay on isolated rat aortas. RESULTS: Telmisartan decreased NO production in normoglycemic and hyperglycemic BAECs, which was accompanied by reduced phosphorylation of eNOS at Ser¹¹⁷⁹ (p-eNOS-Ser¹¹⁷⁹). Telmisartan increased the expression of protein phosphatase 2A catalytic subunit (PP2Ac) and co-treatment with okadaic acid completely restored telmisartan-inhibited NO production and p-eNOS-Ser¹¹⁷⁹ levels. Of the ARBs tested (including losartan and fimasartan), only telmisartan decreased NO production and p-eNOS-Ser¹¹⁷⁹ levels, and enhanced PP2Ac expression. Co-treatment with GW9662 had no effect on telmisartan-induced changes. In line with in vitro observations, telmisartan reduced serum nitrite and p-eNOS-Ser¹¹⁷⁹ levels, and increased PP2Ac expression in high fat diet-fed mice. Furthermore, telmisartan attenuated ACh-induced rat aorta relaxation. CONCLUSION: We demonstrated that telmisartan inhibited NO production and vessel relaxation at least in part by PP2A-mediated eNOS-Ser¹¹⁷⁹ dephosphorylation in a peroxisome proliferator-activated receptor γ-independent manner. These results may provide a mechanism that explains the inconsistent cerebrocardiovascular protective effects of telmisartan.

Angiotensin II Type 1 Receptor Blocker, Fimasartan, Reduces Vascular Smooth Muscle Cell Senescence by Inhibiting the CYR61 Signaling Pathway

BACKGROUND AND OBJECTIVES: Angiotensin II (Ang II) has been suggested to accelerate vascular senescence, however the molecular mechanism(s) remain unknown. METHODS: We cultured human coronary artery smooth muscle cells (hCSMCs) and treated Ang II and/or fimasartan. Or we transfected adenoviral vectors expressing CYR61 (Ad-CYR61) or antisense CYR61 (Ad-As-CYR61). Cellular senescence was evaluated senescence-associated β-galactosidase (SA-β-gal) assay. The molecular mechanisms were investigated real-time PCR and western blots. RESULTS: SA-β-gal-positive cells significantly increased in Ang II-treated hCSMCs (5.77±1.43-fold compared with the control). The effect of Ang II was significantly attenuated by pretreatment with the Ang II type 1 receptor blocker, fimasartan (2.00±0.92-fold). The expression of both p53 and p16 senescence regulators was significantly increased by Ang II (p53: 1.39±0.17, p16: 1.19±0.10-fold vs. the control), and inhibited by fimasartan. Cysteine-rich angiogenic protein 61 (CYR61) was rapidly induced by Ang II. Compared with the control, Ad-CYR61-transfected hCSMCs showed significantly increased SA-β-gal-positive cells (3.47±0.65-fold). Upon transfecting Ad-AS-CYR61, Ang II-induced senescence (3.74±0.23-fold) was significantly decreased (1.77±0.60-fold). p53 expression by Ang II was significantly attenuated by Ad-AS-CYR61, whereas p16 expression was not regulated. Ang II activated ERK1/2 and p38 MAPK, which was significantly blocked by fimasartan. ERK and p38 inhibition both regulated Ang II-induced CYR61 expression. However, p53 expression was only regulated by ERK1/2, whereas p16 expression was only attenuated by p38 MAPK. CONCLUSIONS: Ang II induced vascular senescence by the ERK/p38 MAPK–CYR61 pathway and ARB, fimasartan, protected against Ang II-induced vascular senescence.

Telmisartan increases hepatic glucose production via protein kinase C ζ-dependent insulin receptor substrate-1 phosphorylation in HepG2 cells and mouse liver / 영남의대학술지

BACKGROUND: Dysregulation of hepatic glucose production (HGP) contributes to the development of type 2 diabetes mellitus. Telmisartan, an angiotensin II type 1 receptor blocker (ARB), has various ancillary effects in addition to common blood pressure-lowering effects. The effects and mechanism of telmisartan on HGP have not been fully elucidated and, therefore, we investigated these phenomena in hyperglycemic HepG2 cells and high-fat diet (HFD)-fed mice.METHODS: Glucose production and glucose uptake were measured in HepG2 cells. Expression levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase α (G6Pase-α), and phosphorylation levels of insulin receptor substrate-1 (IRS-1) and protein kinase C ζ (PKCζ) were assessed by western blot analysis. Animal studies were performed using HFD-fed mice.RESULTS: Telmisartan dose-dependently increased HGP, and PEPCK expression was minimally increased at a 40 μM concentration without a change in G6Pase-α expression. In contrast, telmisartan increased phosphorylation of IRS-1 at Ser302 (p-IRS-1-Ser302) and decreased p-IRS-1-Tyr632 dose-dependently. Telmisartan dose-dependently increased p-PKCζ-Thr410 which is known to reduce insulin action by inducing IRS-1 serine phosphorylation. Ectopic expression of dominant-negative PKCζ significantly attenuated telmisartan-induced HGP and p-IRS-1-Ser302 and -inhibited p-IRS-1-Tyr632. Among ARBs, including losartan and fimasartan, only telmisartan changed IRS-1 phosphorylation and pretreatment with GW9662, a specific and irreversible peroxisome proliferator-activated receptor γ (PPARγ) antagonist, did not alter this effect. Finally, in the livers from HFD-fed mice, telmisartan increased p-IRS-1-Ser302 and decreased p-IRS-1-Tyr632, which was accompanied by an increase in p-PKCζ-Thr410.CONCLUSION: These results suggest that telmisartan increases HGP by inducing p-PKCζ-Thr410 that increases p-IRS-1-Ser302 and decreases p-IRS-1-Tyr632 in a PPARγ-independent manner.

Angiotensin II type 1 receptor antibodies in kidney transplantation / 대한이식학회지

Angiotensin II type 1 receptor (AT1R) antibodies directly injure endothelial and vascular smooth muscle cells by activating transcription factors associated with proinflammatory responses. Previous studies have shown that AT1R antibodies are associated with allograft rejection and decreased graft survival in kidney transplantation. Development of enzyme-linked immunosorbent assay has facilitated semiquantitative detection of AT1R antibodies. Assessing AT1R antibodies along with donor specific human leukocyte antigen antibodies may have potential to identify patients with possible risk for allograft injury and improve overall outcomes. In this review, we summarize recent clinical studies about AT1R antibodies in kidney transplantation and provide perspectives for future research area.

Participation of hepatic α/β-adrenoceptors and AT1 receptors in glucose release and portal hypertensive response induced by adrenaline or angiotensin II

It has been previously demonstrated that the hemodynamic effect induced by angiotensin II (AII) in the liver was completely abolished by losartan while glucose release was partially affected by losartan. Angiotensin II type 1 (AT1) and adrenergic (∝1- and β-) receptors (AR) belong to the G-proteins superfamily, which signaling promote glycogen breakdown and glucose release. Interactive relationship between AR and AT1-R was shown after blockade of these receptors with specific antagonists. The isolated perfused rat liver was used to study hemodynamic and metabolic responses induced by AII and adrenaline (Adr) in the presence of AT1 (losartan) and ∝1-AR and β-AR antagonists (prazosin and propranolol). All antagonists diminished the hemodynamic response induced by Adr. Losartan abolished hemodynamic response induced by AII, and AR antagonists had no effect when used alone. When combined, the antagonists caused a decrease in the hemodynamic response. The metabolic response induced by Adr was mainly mediated by ∝1-AR. A significant decrease in the hemodynamic response induced by Adr caused by losartan confirmed the participation of AT1-R. The metabolic response induced by AII was impaired by propranolol, indicating the participation of β-AR. When both ARs were blocked, the hemodynamic and metabolic responses were impaired in a cumulative effect. These results suggested that both ARs might be responsible for AII effects. This possible cross-talk between β-AR and AT1-R signaling in the hepatocytes has yet to be investigated and should be considered in the design of specific drugs.

Clinical Impact of Pre-transplant Antibodies Against Angiotensin II Type I Receptor and Major Histocompatibility Complex Class I-Related Chain A in Kidney Transplant Patients

BACKGROUND: Evidence of antibody-mediated injury in the absence of donor-specific HLA antibodies (HLA-DSA) has recently emerged, suggesting a role of antibodies in targeting non-HLA antigens expressed on renal allograft tissue. However, the clinical significance of pre-transplant non-HLA antibodies remains unclear. We compared the histological and clinical impact of pre-transplant HLA-DSA and non-HLA antibodies, especially angiotensin II type I receptor (anti-AT1R) and MHC class I-related chain A (anti-MICA), in kidney transplant patients. METHODS: Pre-transplant HLA-DSA, anti-AT1R, and anti-MICA were retrospectively examined in 359 kidney transplant patients to determine the effect of each antibody on allograft survival and clinical characteristics. RESULTS: Pre-transplant HLA-DSA, anti-AT1R, and anti-MICA were detected in 37 (10.3%), 174 (48.5%), and 50 patients (13.9%), respectively. Post-transplant antibody-mediated rejection was associated with a pre-transplant HLA-DSA (+) status only. The development of microvascular inflammation (MVI) was associated with pre-transplant HLA-DSA (P=0.001) and anti-AT1R (P=0.036). Anti-AT1R (+) patients had significantly lower allograft survival compared with anti-AT1R (−) patients (P=0.042). Only pre-transplant anti-AT1R positivity was an independent risk factor for allograft failure (hazard ratio 4.824, confidence interval 1.017–24.888; P=0.038). MVI was the most common histological feature of allograft failure in patients with pre-transplant anti-AT1R. CONCLUSIONS: Pre-transplant anti-AT1R is an important risk factor for allograft failure, which may be mediated by MVI induction in the allograft tissue.

Tumor necrosis factor α-converting enzyme inhibitor attenuates lipopolysaccharide-induced reactive oxygen species and mitogen-activated protein kinase expression in human renal proximal tubule epithelial cells

Tumor necrosis factor-α (TNFα) and the angiotensin system are involved in inflammatory diseases and may contribute to acute kidney injury. We investigated the mechanisms by which TNFα-converting enzyme (TACE) contributes to lipopolysaccharide (LPS)-induced renal inflammation and the effect of TACE inhibitor treatment on LPS-induced cellular injury in human renal proximal tubule epithelial (HK-2) cells. Mice were treated with LPS (10 mg/kg, i.p.) and HK-2 cells were cultured with or without LPS (10 µg/ml) in the presence or absence of a type 1 TACE inhibitor (1 µM) or type 2 TACE inhibitor (10 µM). LPS treatment induced increased serum creatinine, TNFα, and urinary neutrophil gelatinase-associated lipocalin. Angiotensin II type 1 receptor, mitogen activated protein kinase (MAPK), and TACE increased, while angiotensin-converting enzyme-2 (ACE2) expression decreased in LPS-induced acute kidney injury and LPS-treated HK-2 cells. LPS induced reactive oxygen species and the down-regulation of ACE2, and these responses were prevented by TACE inhibitors in HK-2 cells. TACE inhibitors increased cell viability in LPS-treated HK-2 cells and attenuated oxidative stress and inflammatory cytokines. Our findings indicate that LPS activates renin angiotensin system components via the activation of TACE. Furthermore, inhibitors of TACE are potential therapeutic agents for kidney injury.

24-Hour blood pressure response to lower dose (30 mg) fimasartan in Korean patients with mild to moderate essential hypertension

BACKGROUND/AIMS: Fimasartan is an angiotensin type 1 receptor blocker (ARB) which has comparable efficacy and tolerability with other ARBs. The aim of this study was to evaluate 24-hour blood pressure (BP) lowering efficacy and the tolerability of the low dose fimasartan compared with valsartan in patients with mild to moderate hypertension. METHODS: This study was a phase II, prospective, multicenter, randomized, double-blind, parallel-grouped trial. A total of 75 hypertensive patients, whose mean ambulatory BP monitoring values were ≥ 135/85 mmHg, were randomized to either fimasartan 30 mg or valsartan 80 mg daily. The primary efficacy endpoint was the change in the mean 24-hour systolic BP (SBP) values from the baseline and at the week 8. Secondary endpoints included the change in the mean 24-hour diastolic BP values, the daytime and the nighttime mean BP values at week 8, the trough-to-peak (T/P) ratio and the smoothness index. RESULTS: At week 8, the mean 24-hour SBP values significantly decreased in both groups; –10.5 ± 11.9 mmHg (p < 0.0001) in the fimasartan group and –5.5 ± 11.6 mmHg (p = 0.0307) in the valsartan group. The difference between two groups was 4.3 ± 2.9 mmHg but there was no statistical significance (p = 0.1392). The global T/P ratio in the fimasartan 30 mg groups were 0.48 and 0.40 in the valsartan 80 mg group, respectively (p = 0.3411). The most frequent adverse events (AEs) were acute pharyngitis and there were no cases of severe AEs. CONCLUSIONS: In mild-to-moderate hypertensive patients, low dose (30 mg) fimasartan showed comparable 24-hour BP lowering efficacy compared with valsartan (80 mg). There was no difference in tolerability between two groups.

Comparative effects of angiotensin II and angiotensin-(4-8) on blood pressure and ANP secretion in rats

Angiotensin II (Ang II) is metabolized from N-terminal by aminopeptidases and from C-terminal by Ang converting enzyme (ACE) to generate several truncated angiotensin peptides (Angs). The truncated Angs have different biological effects but it remains unknown whether Ang-(4-8) is an active peptide. The present study was to investigate the effects of Ang-(4-8) on hemodynamics and atrial natriuretic peptide (ANP) secretion using isolated beating rat atria. Atrial stretch caused increases in atrial contractility by 60% and in ANP secretion by 70%. Ang-(4-8) (0.01, 0.1, and 1 µM) suppressed high stretch-induced ANP secretion in a dose-dependent manner. Ang-(4-8) (0.1 µM)-induced suppression of ANP secretion was attenuated by the pretreatment with an antagonist of Ang type 1 receptor (AT₁R) but not by an antagonist of AT₂R or AT₄R. Ang-(4-8)-induced suppression of ANP secretion was attenuated by the pretreatment with inhibitor of phospholipase (PLC), inositol triphosphate (IP₃) receptor, or nonspecific protein kinase C (PKC). The potency of Ang-(4-8) to inhibit ANP secretion was similar to Ang II. However, Ang-(4-8) 10 µM caused an increased mean arterial pressure which was similar to that by 1 nM Ang II. Therefore, we suggest that Ang-(4-8) suppresses high stretch-induced ANP secretion through the AT₁R and PLC/IP₃/PKC pathway. Ang-(4-8) is a biologically active peptide which functions as an inhibition mechanism of ANP secretion and an increment of blood pressure.

Association of polymorphisms within the Renin-Angiotensin System with metabolic syndrome in a cohort of Chilean subjects

ABSTRACT Objective Metabolic syndrome (MetS) is associated with hypertension, obesity and dyslipidemia. Thus, genetic variants related with these conditions may modulate its development. We evaluated the effect of polymorphisms in the renin-angiotensin system (RAS) on metabolic syndrome risk in a cohort of Chilean subjects. Subjects and methods A total of 152 subjects, 83 with MetS (51.2 ± 9.6 years) and 69 without MetS (49.5 ± 9.3 years) of both genders were included, according to the ATP III update criteria. The rs4340 Insertion/Deletion (I/D), rs699 (T>C) and rs5186 (A>C) of the ACE, AGT and AGTR1 genes, respectively, were genotyped. Results After adjusting for age and gender, we observed the DD genotype of rs4340 associated with MetS (p = 0.02). Specifically, the DD genotype was associated with MetS risk in women (OR = 4.62, 95%CI, 1.41 – 15.04; p < 0.01). In males, the AA genotype for rs5186 variant was associated with an increased risk for developing MetS when compared with women carrying the same genotype (OR = 3.2; 95%CI, 1.03 – 9.89; p = 0.04). In subjects without MetS, DD genotype was associated with increased waist circumference (p = 0.023) while subjects with MetS carrying the rs5186 TT genotype showed higher levels of HDL-cholesterol (p = 0.031). Conclusion The present study contributes data highlighting the role for RAS polymorphisms in predisposing to metabolic syndrome in Chilean subjects.

Effect of electroacupuncture stimulation on expression of angiotensinogen, angiotensin II type 1 receptor, endothelin-1, and endothelin a receptor mRNA in spontaneously hypertensive rat aorta / 中国结合医学杂志

<p><b>OBJECTIVE</b>To observe the effect of electroacupuncture (EA) stimulation on the expressions of angiotensinogen (AGT), angiotensin II type 1 receptor (AT1R), endothelin-1 (ET1), and endothelin A receptor (ETAR) mRNA in spontaneously hypertensive rat (SHR) aorta.</p><p><b>METHODS</b>Eighteen male SHRs were randomly divided into three groups, an SHR group, an SHR Baihui (DU 20) and Zusanli (ST 36) acupoint (SHR-AP) group, and an SHR non-acupoint (SHR-NAP) group, with 6 rats in each group. Six Wistar rats were used as a control. Rats in the SHR-AP group were stimulated by DU 20 and ST 36 acupoints, both of which were connected with EA. EA was handled one time every Monday, Wednesday and Friday, for total 24 times (8 weeks). SHRNAP rats were acupointed at a 15°angle flat into 0.5 cm to two points, which were 1 and 2 cm from rail tip separately. EA parameters were the same as the SHR-AP rats. SHR control rats and Wistar rats were fixed without EA. Real-time quantitative polymerase chain reaction (PCR) was used to measure AGT, AT1R, ET1, and ETAR mRNA expression in rat aorta.</p><p><b>RESULTS</b>EA stimulation significantly reduced rat aorta vascular AGT, ET1, ETAR and AT1R mRNA expressions in the SHR-AP and SHR-NAP groups (P <0.01). Among these four genes, AT1R mRNA expression was significantly lower in the SHR-AP than in the SHR-NAP group (P <0.01).</p><p><b>CONCLUSION</b>EA could reduce the AT1R mRNA expression in SHR-AP rat aorta, indicating a potential mechanism for the hypotensive effects of EA.</p>

Protective effect and mechanism of β-CM7 on renin angiotensin system & diabetic cardiomyopathy / 生物工程学报

This article aimed at exploring the effects and protective mechanism of β-CM7 on renin angiotensin system (RAS) in diabetic rats myocardial tissue. We divided 32 male SD rats into 4 groups: control group, diabetic model control group, insulin (3.7x10(-8) mol/d) treatment group and β-CM7 (7.5x10(-8) mol/d) treatment group. After 30 days, all rats were decapitated and myocardical tissues were collected immediately. After injection, β-CM7 could decrease the content of Ang II, increase the content of Angl-7. And β-CM7 could improve the mRNA of AT1 receptor and Mas receptor. β-CM7 also could improve the mRNA of ACE and ACE2, enhance the activity of ACE and ACE2. These data confirmed tli β-CM7 could activate ACE2-Angl-7-Mas axis, negative passage in RAS, to inhibit the expression ACE mnRiJA and protein in rat myocardium, alleviate the myocardial tissue damage induced by Ang II. The effect of β-CM7 on inhibiting myocardium damage might be related to ACE/ACE2 passageway.

Avaliação dos eixos ECA / ANG II / AT1 e ECA-2 / ANG (1-7) / MAS em fibroblastos de gengiva e ligamento periodontal humanos estimulados por IL-1ß e sua contribuição na produção e regulação de citocinas e quimiocinas / Evaluation ACE /ANG II /AT1 and ACE-2 /ANG (1-7) /MAS axis in gingival and periodontal ligament human fibroblasts stimulated with IL-1ß and its contribution in the production of cytokines and chemokines

O Sistema renina-angiotensina (SRA) tem sido relatado como um importante modulador de processos inflamatórios e imunológicos, incluindo a doença periodontal (DP). Estudos sugerem neste sistema um eixo alternativo (ECA-2 /ANG(1-7) /MAS) que atuaria como um contra-regulador de efeitos mediados pelo clássico eixo (ECA /ANGII /AT1). Sabe-se que bactérias periodontopatogênicas, como a Porphyromonas gingivalis (Pg), possuem componentes bioativos de membrana (ex. lipopolissacarídeos-LPS) capazes de induzir uma forte resposta imune no hospedeiro devido à liberação de citocinas nas células, entre elas Interleucina (IL)- 1ß. Neste contexto, fibroblastos são as células mais abundantes nos tecidos periodontais e possuem em sua superfície celular receptores necessários para o reconhecimento da invasão bacteriana, ativando cascatas intracelulares, que levam à produção de citocinas. O objetivo deste estudo foi verificar se os eixos ECA/ ANGII/ AT1 e ECA-2/ ANG(1-7)/ MAS contribuem para a produção e/ ou regulação de citocinas inflamatórias (CI) por fibroblastos de gengiva humana (HGF) e ligamento periodontal humano (HPLF) estimulados por IL-1ß. Após o pré-tratamento com Losartan e Ang (1-7) ou silenciamento mediado por RNA de interferência (RNAi) de AT1, HGF e HPLF foram estimulados por IL-1ß por 3 horas (RNAm) ou 24 horas (proteína). Expressão de RNAm para AT1, MAS, ECA, ECA-2, IL-1ß, TNF-α, IL-6, IL-8, IL-10, TGF-ß, CXCL12, RANK-L e OPG foram avaliados por RT-qPCR e das proteínas IL-6, IL-8, ECA e ECA-2 por ELISA. Foi realizado também Western Blot para detecção de AT1 e ECA nos extratos celulares e dosagem de nitrito no sobrenadante das culturas. Ambos os subtipos de fibroblastos mostraram aumento da expressão de RNAm para AT1, IL-1ß, IL-6, IL-8, TNF-α e OPG, quando estimulados por IL-1ß. No entanto, apenas em HPLF foi observado aumento para MAS, ECA e TGF-ß. Losartan e Ang (1-7) não modularam o transcrito, a secreção de CI e nem a produção de nitrito no sobrenadante das culturas, tanto em HGF como em HPLF. O silenciamento do receptor AT1 reduziu a secreção de IL-6 e IL-8 induzida por IL-1ß em cultura de HGF e HPLF e aumentou a expressão gênica de OPG somente em HGF. Estes resultados sugerem que o silenciamento de AT1, mas não o bloqueio farmacológico deste receptor pelo antagonista Losartan, em HGF e HPLF, pode controlar a produção de IL-6 e IL-8, que por sua vez contribuem para a patogênese periodontal.(AU)

The renin-angiotensin system (RAS) has been reported as an important modulator of inflammatory and immune responses, including periodontal disease (PD). Studies suggest an alternative axis as part of this system (ACE-2 / ANG (1-7) / MAS) that would act as counter-regulatory to the classical axis (ECA / ANGII / AT1). It is known that periodontal bacteria such as Porphyromonas gingivalis (Pg) have bioactive components in their membrane (such as lipopolysaccharide-LPS) capable of inducing a strong immune response in the host due to the release of cytokines in cells, including interleukin (IL) - 1ß. In this regard, fibroblasts are the most abundant cells in periodontal tissues and receptors needed for the recognition of bacterial invasion by activating intracellular cascades that lead to cytokine production. The aim of this study was to determine whether the axes ACE / ANGII / AT1 and ACE-2 / ANG (1-7) / MAS contribute to the production and / or regulation of inflammatory cytokines (IC) by fibroblasts of human gingiva (HGF) and human periodontal ligament (HPLF) stimulated IL-1ß. After pre-treatment with Losartan, Ang (1-7) or silencing mediated by RNA interference (RNAi) of AT1, HGF and HPLF were stimulated by IL-1ß for 3 hours (RNAm) or 24 hours (protein). Expression mRNA for AT1, MAS, ACE, ACE-2, IL-1ß, TNF-α, IL-6, IL-8, IL-10, TGF-ß, CXCL12, RANK-L and OPG was assessed by RT- qPCR and proteins IL-6, IL-8, ACE and ACE-2 by ELISA. Western Blot for the detection of AT1 and ECA and dosage of nitrite was also performed. Experiments stimulated by IL-1ß showed a positive control for gene expression AT1, IL-1ß, IL-6, IL-8, TNF-α and OPG in HGF and HPLF and MAS, ACE and TGF-ß only HPLF. Losartan and Ang (1-7) did not modulate the transcription and secretion of IC and no nitrite production in the culture supernatant of HGF and HPLF. The silencing AT1 reduced IL-6 secretion and IL-8 induced by IL- ß in cultured HGF and HPLF and increased OPG gene expression only HGF. These results suggest that silencing AT1, but not pharmacological blockade of this receptor by Losartan in HPLF and HGF, can control the production of IL-6 and IL-8, which in turn contribute to the pathogenesis of periodontal disease.(AU)

Regulatory effects of AT₁R-TRAF6-MAPKs signaling on proliferation of intermittent hypoxia-induced human umbilical vein endothelial cells / 华中科技大学学报（医学）（英德文版）

Endothelial dysfunction induced by intermittent hypoxia (IH) participates in obstructive sleep apnea syndrome (OSAS)-associated cardiovascular disorders. Myeloid differentiation primary response 88 (MyD88) and tumor necrosis factor receptor-associated factor 6 (TRAF6) regulate numerous downstream adaptors like mitogen-activated protein kinases (MAPKs) and the subsequent oxidative stress and inflammatory responses. This study aimed to characterize the role of MyD88/TRAF6 in IH-treated cell function and its associated signaling. Human umbilical vein endothelial cells (HUVECs) were randomly exposed to IH or normoxia for 0, 2, 4 and 6 h. Western blotting was used to detect the expression pattern of target gene proteins [angiotensin 1 receptor (AT1R), p-ERK1/2, p-p38MAPK, MyD88 and TRAF6], and the relationships among these target genes down-regulated by the corresponding inhibitors were studied. Finally, the influence of these target genes on proliferation of HUVECs was also assessed by EdU analysis. Protein levels of AT1R, TRAF6 and p-ERK1/2 were increased after IH exposure, with a slight rise in MyD88 and a dynamic change in p-p38MAPK. The down-regulation of TRAF6 by siRNA reduced ERK1/2 phosphorylation during IH without any effects on AT1R. Blockade of AT1R with valsartan decreased TRAF6 and p-ERK1/2 protein expression after IH exposure. ERK1/2 inhibition with PD98059 suppressed only AT1R expression. IH promoted HUVECs proliferation, which was significantly suppressed by the inhibition of TRAF6, AT1R and ERK1/2. The findings demonstrate that TRAF6 regulates the proliferation of HUVECs exposed to short-term IH by modulating cell signaling involving ERK1/2 downstream of AT1R. Targeting the AT1R-TRAF6-p-ERK1/2 signaling pathway might be helpful in restoring endothelial function.

Protective effects of Sapindus saponins in spontaneously hypertensive rats / 中国结合医学杂志

<p><b>OBJECTIVES</b>To investigate the protective effects of Sapindus saponins in spontaneously hypertensive rats, and the possible cellular and molecular mechanisms.</p><p><b>METHODS</b>Thirty-two 16-week-old spontaneously hypertensive rats were randomly divided into four groups (8 in each group): model group (placebo), positive control group (27 mg/kg of Captopril Tablets), Sapindus saponins groups (27 mg/kg and 108 mg/kg, respectively). Another 8 healthy Wistar-Kyoto strain (WKY) rats were used as the normal group. The animals were treated for 8 weeks. Blood pressure of rats was determined by non-invasive blood pressure meter (BP-6). Furthermore, the contents of angiotensin II (Ang II) in plasma and myocardial tissue were determined by enzyme-linked immunosorbent assay (ELISA), the gene expression of receptor angiotensin type 1 (AT1R) in aorta was determined by quantitative realtime polymerase chain reaction (qRT-PCR). The protein expression of transforming growth factor-β1 (TGF-β1) and AT1R in heart was determined by immunohistochemical staining. The protein expression of p-phosphorylation of p38 mitogen-activated protein kinase (p-p38MAPK) was determined by Western blotting. The contents of interleukin (IL)-1, IL-6 and tumor necrosis factor (TNF) in serum were determined by radioimmunoassay. And the histopathological and morphological changes of aorta and heart tissue samples were assessed semi-quantitatively by hematoxylin-eosin (HE) or Masson staining.</p><p><b>RESULTS</b>Thirty minutes after single or continuous treatment, systolic blood pressure (SBP) was reduced significantly in Sapindus saponins groups. And the contents of AngII, IL-1, IL-6 and TNF-α in serum, the expression of AT1R mRNA, p-p38MAPK and TGF-β1 were significantly suppressed dose-dependently (P<0.05 or P<0.01). With the Sapindus saponins treatment, compared with those of the model group, the cardiac and aortic pathological changes were ameliorated significantly.</p><p><b>CONCLUSIONS</b>Our findings suggest that Sapindus saponins might have protective effects in spontaneously hypertensive rats, the cellular and molecular mechanisms of which might be relevant to the regulation of inflammatory responses mediated by p-p38MAPK signal pathway based on activated Ang II and AT1R.</p>

A Novel Angiotensin Type I Receptor Antagonist, Fimasartan, Prevents Doxorubicin-induced Cardiotoxicity in Rats

Angiotensin receptor blockers (ARBs) have organ-protective effects in heart failure and may be also effective in doxorubicin-induced cardiomyopathy (DOX-CMP); however, the efficacy of ARBs on the prevention of DOX-CMP have not been investigated. We performed a preclinical experiment to evaluate the preventive effect of a novel ARB, fimasartan, in DOX-CMP. All animals underwent echocardiography and were randomly assigned into three groups: treated daily with vehicle (DOX-only group, n=22), 5 mg/kg of fimasartan (Low-fima group, n=22), and 10 mg/kg of fimasartan (High-fima group, n=19). DOX was injected once a week for six weeks. Echocardiography and hemodynamic assessment was performed at the 8th week using a miniaturized conductance catheter. Survival rate of the High-fima group was greater (100%) than that of the Low-fima (75%) and DOX-only groups (50%). Echocardiography showed preserved left ventricular (LV) ejection fraction in the High-fima group, but not in the DOX-only group (P=0.002). LV dimensions increased in the DOX-only group; however, remodeling was attenuated in the Low-fima and High-fima groups. Hemodynamic assessment showed higher dP/dt in the High-fima group compared with the DOX-only group. A novel ARB, fimasartan, may prevent DOX-CMP and improve survival rate in a dose-dependent manner in a rat model of DOX-CMP and could be a treatment option for the prevention of DOX-CMP.

Investigation of Serum Angiotensin II Type 1 Receptor Antibodies at the Time of Renal Allograft Rejection

BACKGROUND: Angiotensin II type 1 receptor (AT1R) is responsible for cardiovascular effects mediated by angiotensin II. This study aimed to investigate the impact of antibodies directed against AT1R (anti-AT1R) in renal allograft rejection. METHODS: We evaluated 53 patients who had biopsy-proven rejection including antibody-mediated rejection (AMR) (N=22), T-cell-mediated rejection (TCMR) (N=29), and mixed AMR and TCMR (N=2). Donor specific HLA antibodies (DSA) and anti-AT1Rs were simultaneously determined. RESULTS: Anti-AT1Rs were detected in 9.4% (5/53) of rejection patients (one with acute AMR, two with chronic active AMR, one with acute TCMR, and one with mixed acute AMR & TCMR). HLA antibodies and DSA were detected in 75.5% (40/53) and 49.1% (26/53) of patients, respectively. There was no significant difference in transplant characteristics between anti-AT1R(+) and anti-AT1R(-) patients except for the association of HLA class-I DSA(+) and anti-AT1R(+). Four of five anti-AT1R(+) patients had DSA and were also found to have AMR. A single anti-AT1R(+)/DSA(-) patient developed acute TCMR. Detection rates of DSA, HLA antibodies, or anti-AT1R were not different between AMR and TCMR. However, DSA(+)/anti-AT1R(+) was more frequently found in AMR than in TCMR (P=0.036). Patients with anti-AT1R showed a greater tendency to develop high-grade rejection as Banff IIA/IIB or AMR. CONCLUSIONS: The presence of anti-AT1R was significantly associated with HLA class-I DSA in renal allograft rejection patients. Both anti-AT1R and DSA positivity was associated with AMR in patients with renal allograft rejection.