The Mas agonist CGEN-856S prevents Ang II induced cardiomyocyte hypertrophy via nitric oxide production

With the previous knowledge of the cardioprotective effects of the Angiotensin-(1-7) axis, a agonist of Mas receptor has been described, the CGEN-856S. This peptide is more stable than Ang-(1-7), and has a low binding affinity to Angiotensin II receptors. Although the cardioprotective effects of CGEN-856S were previously shown in vivo, the mechanisms behind its effects are still unknown. Here, we employed a combination of molecular biology, confocal microscopy, and genetically modified mouse with Mas deletion to investigate the CGEN-856S protective signaling in cardiomyocytes. In isolated adult ventricular myocytes, CGEN-856S induced an increase in nitric oxide (NO) production which was absent in cells from Mas knockout mice. Using western blot, we observed a significant increase in phosphorylation of AKT after treatment with CGEN-856S. In addition, CGEN-856S prevented the Ang II induced hypertrophy and the nuclear translocation of GRK5 in a culture model of rat neonatal cardiomyocytes. Blockage of Mas receptor and inhibition of the NO synthase abolished the effects of CGEN-856S on Ang II treated cardiomyocytes. In conclusion, we show that CGEN-856S acting via receptor Mas induces NO raise to block Ang II induced cardiomyocyte hypertrophy. These results indicate that CGEN-856S acts very similarly to Ang-(1-7) in cardiac myocytes, highlighting its therapeutic potential for treating cardiovascular diseases.

Possible role of metformin as an antidepressant in diabetes

OBJECTIVE

Metformin (MET) is a drug used in the treatment of type 2 diabetes due to its insulin receptor sensitizing properties and anti-hepatic gluconeogenesis effect. One of the comorbidities in diabetes is the depression. This review aimed at summarizing the results of the available MET, depression and diabetes studies to clarify the possible role of MET in the depression during diabetes.

METHODS

A bibliographic search on PubMed, Embase, PsycINFO, Web of Science, Cochrane Central for studies referring to MET, depression and diabetes.

RESULTS

Several studies have associated depression to the chronic inflammation that characterizes diabetes. Additionally MET is an anti-inflammatory molecule that generally acts by activating AMPK and inhibiting the NF-kB factor. In the context of diabetes, MET can act directly as an anti-inflammatory drug as well as inhibiting other pro-inflammatory molecules. In this regard, MET may inhibit the pro-inflammatory effects of angiotensin II. By facilitating the action of insulin and reducing hepatic gluconeogenesis, MET reduces circulating glucose levels, decreasing the formation of advanced glycation end products and therefore inflammation. During diabetes, the gut microbiota and the permeability of the intestinal barrier are altered, causing high levels of circulating lipopolysaccharides (LPS), which induce inflammation. MET can normalize the microbiota and the intestinal barrier permeability reducing the levels of LPS and inflammation. Clinical and experimental studies show the anti-depressant effect of MET mediated by different mechanisms both at the peripheral level and in the central nervous system.

CONCLUSION

Therefore, MET as an anti-inflammatory drug can decrease symptoms of depression and represents a therapeutic approach to improve the psychological state of patients with diabetes. Additionally, insulin also has an anti-inflammatory effect that could act together with MET.

Angiotension II directly bind P2X7 receptor to induce myocardial ferroptosis and remodeling by activating human antigen R

Continuous remodeling of the heart can result in adverse events such as reduced myocardial function and heart failure. Available evidence indicates that ferroptosis is a key process in the emergence of cardiac disease. P2 family purinergic receptor P2X7 receptor (P2X7R) activation plays a crucial role in numerous aspects of cardiovascular disease. The aim of this study was to elucidate any potential interactions between P2X7R and ferroptosis in cardiac remodeling stimulated by angiotensin II (Ang II), and P2X7R knockout mice were utilized to explore the role of P2X7R and elucidate its underlying mechanism through molecular biological methods. Ferroptosis is involved in cardiac remodeling, and P2X7R deficiency significantly alleviates cardiac dysfunction, remodeling, and ferroptosis induced by Ang II. Mechanistically, Ang II interacts with P2X7R directly, and LYS-66 and MET-212 in the in the ATP binding pocket form a binding complex with Ang II. P2X7R blockade influences HuR-targeted GPX4 and HO-1 mRNA stability by affecting the shuttling of HuR from the nucleus to the cytoplasm and its expression. These results suggest that focusing on P2X7R could be a possible therapeutic approach for the management of hypertensive heart failure.

Unraveling the complex pathophysiology of heart failure: insights into the role of renin-angiotensin-aldosterone system (RAAS) and sympathetic nervous system (SNS)

Heart failure (HF) is a widespread disease with significantly elevated mortality, morbidity, and hospitalization rates. Dysregulation of the sympathetic nervous system (SNS) and renin-angiotensin-aldosterone system (RAAS) are both postulated to be significant regulators of cardiovascular function, thereby playing a pivotal role in its pathophysiology. The RAAS is a sophisticated hormonal system that controls electrolyte homeostasis, fluid balance, and blood pressure. Angiotensin II, which operates to constrict blood vessels and raise blood pressure, is its principal effector molecule. The RAAS is frequently hyperactive in HF, which increases fluid retention and worsens cardiac function. The SNS is frequently hyperactive in heart failure, which increases the workload on the heart and worsens symptoms. This review will discuss what is currently known about the pathophysiology of heart failure, specifically in the context of RAAS and the SNS, in-depth to emphasize the knowledge gap that necessitates more research.

Evidence for heterodimerization and functional interaction of the urotensin II and the angiotensin II type 1 receptors

Despite the observation of synergistic interactions between the urotensinergic and angiotensinergic systems, the interplay between the urotensin II receptor (hUT) and the angiotensin II type 1 receptor (hAT1R) in regulating cellular signaling remains incompletely understood. Notably, the putative interaction between hUT and hAT1R could engender reciprocal allosteric modulation of their signaling signatures, defining a unique role for these complexes in cardiovascular physiology and pathophysiology. Using a combination of co-immunoprecipitation, bioluminescence resonance energy transfer (BRET) and FlAsH BRET-based conformational biosensors, we first demonstrated the physical interaction between hUT and hAT1R. Next, to analyze how this functional interaction regulated proximal and distal hUT- and hAT1R-associated signaling pathways, we used BRET-based signaling biosensors and western blots to profile pathway-specific signaling in HEK 293 cells expressing hUT, hAT1R or both. We observed that hUT-hAT1R heterodimers triggered distinct signaling outcomes compared to their respective parent receptors alone. Notably, co-transfection of hUT and hAT1R has no impact on hUII-induced Gq activation but significantly reduced the potency and efficacy of Ang II to mediate Gq activation. Interestingly, URP, the second hUT endogenous ligand, produce a distinct signaling signature compared to hUII at hUT-hAT1R. Our results therefore suggest that assembly of hUT with hAT1R might be important for allosteric modulation of outcomes associated with specific hardwired signaling complexes in healthy and disease states. Altogether, our work, which potentially explains the interplay observed in native cells and tissues, validates such complexes as potential targets to promote the design of compounds that can modulate heterodimer function selectively.

The antihypertensive action of C-phycocyanin is related to the prevention of angiotensin II-caused vascular dysfunction in chronic kidney disease

C-phycocyanin (CPC) is a photosynthetic protein found in Arthrospira maxima with a nephroprotective and antihypertensive activity that can prevent the development of hemodynamic alterations caused by chronic kidney disease (CKD). However, the complete nutraceutical activities are still unknown. This study aims to determine if the antihypertensive effect of CPC is associated with preventing the impairment of hemodynamic variables through delaying vascular dysfunction. Twenty-four normotensive male Wistar rats were divided into four groups: (1) sham + 4 mL/kg/d vehicle (100 mM of phosphate buffer, PBS) administered by oral gavage (og), (2) sham + 100 mg/kg/d og of CPC, (3) CKD induced by 5/6 nephrectomy (CKD) + vehicle, (4) CKD + CPC. One week after surgery, the CPC treatment began and was administrated daily for four weeks. At the end treatment, animals were euthanized, and their thoracic aorta was used to determine the vascular function and expression of AT1, AT2, and Mas receptors. CKD-induced systemic arterial hypertension (SAH) and vascular dysfunction by reducing the vasorelaxant response of angiotensin 1-7 and increasing the contractile response to angiotensin II. Also, CKD increased the expression of the AT1 and AT2 receptors and reduced the Mas receptor expression. Remarkably, the treatment with CPC prevented SAH, renal function impairment, and vascular dysfunction in the angiotensin system. In conclusion, the antihypertensive activity of CPC is associated with avoiding changes in the expression of AT1, AT2, and Mas receptors, preventing vascular dysfunction development and SAH in rats with CKD.

Role of Angiotensin II in Non-Alcoholic Steatosis Development

Fatty liver is a multifactorial disease characterized by excessive accumulation of lipids in hepatocytes (steatosis), insulin resistance, oxidative stress, and inflammation. This disease has a major public health impact because it is the first stage of a chronic and degenerative process in the liver that can lead to steatohepatitis, cirrhosis, and liver cancer. Although this disease is mainly diagnosed in patients with obesity, type 2 diabetes mellitus, and dyslipidemia, recent evidence indicates that vasoactive hormones such as angiotensin II (ANGII) not only promote endothelial dysfunction (ED) and hypertension, but also cause fatty liver, increase adipose tissue, and develop a pro-steatotic environment characterized by a low-grade systemic pro-inflammatory and pro-oxidant state, with elevated blood lipid levels. The role of ANGII in lipid accumulation has been little studied, so this review aims to summarize existing reports on the possible mechanism of action of ANGII in inducing lipid accumulation in hepatocytes.

The scientific rationale and study protocol for the DPP3, Angiotensin II, and Renin Kinetics in Sepsis (DARK-Sepsis) randomized controlled trial: serum biomarkers to predict response to angiotensin II versus standard-of-care vasopressor therapy in the treatment of septic shock

BACKGROUND

Data to support the use of specific vasopressors in septic shock are limited. Since angiotensin II (AT2) was approved by the Food and Drug Administration in 2017, multiple mechanistically distinct vasopressors are available to treat septic shock, but minimal data exist regarding which patients are most likely to benefit from each agent. Renin and dipeptidyl peptidase 3 (DPP3) are components of the renin-angiotensin-aldosterone system which have been shown to outperform lactate in predicting sepsis prognosis, and preliminary data suggest they could prove useful as biomarkers to guide AT2 use in septic shock.

METHODS

The DARK-Sepsis trial is an investigator-initiated industry-funded, open-label, single-center randomized controlled trial of the use of AT2 versus standard of care (SOC) vasopressor therapy in patients admitted to the intensive care unit (ICU) with vasodilatory shock requiring norepinephrine ≥ 0.1 mcg/kg/min. In both groups, a series of renin and DPP3 levels will be obtained over the first 24 h of treatment with AT2 or SOC. The primary study outcome will be the ability of these biomarkers to predict response to vasopressor therapy, as measured by change in total norepinephrine equivalent dose of vasopressors at 3 h post-drug initiation or the equivalent timepoint in the SOC arm. To determine if the ability to predict vasopressor response is specific to AT2 therapy, the primary analysis will be the ability of baseline renin and DPP3 levels to predict vasopressor response adjusted for treatment arm (AT2 versus control) and Sequential Organ Failure Assessment (SOFA) scores. Secondary outcomes will include rates of acute kidney injury, need for mechanical ventilation and kidney replacement therapy, lengths of stay in the ICU and hospital, ICU and hospital mortality, and rates of prespecified adverse events.

DISCUSSION

With an armamentarium of mechanistically distinct vasopressor agents now available, sub-phenotyping patients using biomarkers has the potential to improve septic shock outcomes by enabling treatment of the correct patient with the correct vasopressor at the correct time. However, this approach requires validation in a large definitive multicenter trial. The data generated through the DARK-Sepsis study will prove crucial to the optimal design and patient enrichment of such a pivotal trial.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05824767. Registered on April 24, 2023.

Chymase-independent vascular Ang-(1-12)/Ang II pathway and TXA2 generation are involved in endothelial dysfunction in the murine model of heart failure

The angiotensin (Ang)-(1-12)/Ang II pathway contributes to cardiac pathology. However, its involvement in the development of peripheral endothelial dysfunction associated with heart failure (HF) remains unknown. Therefore, this study aimed to characterise the effect of exogenous Ang-(1-12) and its conversion to Ang II on endothelial function using the murine model of HF (Tgαq*44 mice), focusing on the role of chymase and vascular-derived thromboxane A2 (TXA2). Ex vivo myographic assessments of isolated aorta showed impaired endothelium-dependent vasodilation in late-stage HF in 12-month-old Tgαq*44 mice. However, endothelium-dependent vasodilation was fully preserved in the early stage of HF in 4-month-old Tgαq*44 mice and 4- and 12-month-old FVB control mice. Ang-(1-12) impaired endothelium-dependent vasodilation in 4- and 12-month-old Tgαq*44 mice, that was associated with increased Ang II production. The chymase inhibitor chymostatin did not inhibit this response. Interestingly, TXA2 production reflected by TXB2 measurement was upregulated in response to Ang-(1-12) and Ang II in aortic rings isolated from 12-month-old Tgαq*44 mice but not from 4-month-old Tgαq*44 mice or age-matched FVB mice. Furthermore, in vivo magnetic resonance imaging showed that Ang-(1-12) impaired endothelium-dependent vasodilation in the aorta of Tgαq*44 mice and FVB mice. However, this response was inhibited by angiotensin I converting enzyme (ACE) inhibitor; perindopril, angiotensin II receptor type 1 (AT1) antagonist; losartan and TXA2 receptor (TP) antagonist-picotamide in 12-month-old-Tgαq*44 mice only. In conclusion, the chymase-independent vascular Ang-(1-12)/Ang II pathway and subsequent TXA2 overactivity contribute to systemic endothelial dysfunction in the late stage of HF in Tgαq*44 mice. Therefore, the vascular TXA2 receptor represents a pharmacotherapeutic target to improve peripheral endothelial dysfunction in chronic HF.

High Dose of Estrogen Protects the Lungs from Ischemia-Reperfusion Injury by Downregulating the Angiotensin II Signaling Pathway

We explored the sex difference in lung ischemia-reperfusion injury (LIRI) and the role and mechanism of estrogen (E2) and angiotensin II (Ang II) in LIRI. We established a model of LIRI in mice. E2, Ang II, E2 inhibitor (fulvestrant), and angiotensin II receptor blocker (losartan) were grouped for treatment. The lung wet/dry weight ratio, natural killer (NK) cells (by flow cytometry), neutrophils (by flow cytometry), expression of key proteins (by Western blot, immunohistochemistry, ELISA, and immunofluorescence), and expression of related protein mRNA (by qPCR) were detected. The ultrastructure of the alveolar epithelial cells was observed by transmission electron microscopy. We found that E2 and Ang II played an important role in the progression of LIRI. The two signaling pathways showed obvious antagonism, and E2 regulates LIRI in the different sexes by downregulating Ang II, leading to a better prognosis. E2 and losartan reduced the inflammatory cell infiltration in lung tissue and key inflammatory factors in serum while fulvestrant and Ang II had the opposite effect. The protective effect of E2 was related with AKT, p38, COX2, and HIF-1α.

Angiotensin ii therapy in refractory septic shock: which patient can benefit most? A narrative review

Patients with septic shock who experience refractory hypotension despite adequate fluid resuscitation and high-dose noradrenaline have high mortality rates. To improve outcomes, evidence-based guidelines recommend starting a second vasopressor, such as vasopressin, if noradrenaline doses exceed 0.5 µg/kg/min. Recently, promising results have been observed in treating refractory hypotension with angiotensin II, which has been shown to increase mean arterial pressure and has been associated with improved outcomes. This narrative review aims to provide an overview of the pathophysiology of the renin-angiotensin system and the role of endogenous angiotensin II in vasodilatory shock with a focus on how angiotensin II treatment impacts clinical outcomes and on identifying the population that may benefit most from its use.

Mitochondrial fission inhibition protects against hypertension induced by angiotensin II

Mitochondrial dysfunction has been implicated in various types of cardiovascular disease including hypertension. Mitochondrial fission fusion balance is critical to mitochondrial quality control, whereas enhanced fission has been reported in several models of cardiovascular disease. However, limited information is available regarding the contribution of mitochondrial fission in hypertension. Here, we have tested the hypothesis that inhibition of mitochondrial fission attenuates the development of hypertension and associated vascular remodeling. In C57BL6 mice infused with angiotensin II for 2 weeks, co-treatment of mitochondrial fission inhibitor, mdivi1, significantly inhibited angiotensin II-induced development of hypertension assessed by radiotelemetry. Histological assessment of hearts and aortas showed that mdivi1 inhibited vessel fibrosis and hypertrophy induced by angiotensin II. This was associated with attenuation of angiotensin II-induced decline in mitochondrial aspect ratio seen in both the endothelial and medial layers of aortas. Mdivi1 also mitigated angiotensin II-induced cardiac hypertrophy assessed by heart weight-to-body weight ratio as well as by echocardiography. In ex vivo experiments, mdivi1 inhibited vasoconstriction and abolished the enhanced vascular reactivity by angiotensin II in small mesenteric arteries. Proteomic analysis on endothelial cell culture media with angiotensin II and/or mdivi1 treatment revealed that mdivi1 inhibited endothelial cell hypersecretory phenotype induced by angiotensin II. In addition, mdivi1 attenuated angiotensin II-induced protein induction of periostin, a myofibroblast marker in cultured vascular fibroblasts. In conclusion, these data suggest that mdivi1 prevented angiotensin II-induced hypertension and cardiovascular remodeling via multicellular mechanisms in the vasculature.

A central arteriovenous fistula reduces systemic hypertension in a mouse model

Objective

A central arteriovenous fistula (AVF) has been proposed as a potential novel solution to treat patients with refractory hypertension. We hypothesized that venous remodeling after AVF creation in the hypertensive environment reduces systemic blood pressure but results in increased AVF wall thickness compared with remodeling in the normotensive environment.

Methods

A central AVF was performed in C57BL6/J mice previously made hypertensive with angiotensin II (Ang II); mice were sacrificed on postoperative day 7 or 21.

Results

In mice treated with Ang II alone, the mean systolic blood pressure increased from 90 ± 5 mmHg to 160 ± 5 mmHg at day 21; however, in mice treated with both Ang II and an AVF, the blood pressure decreased with creation of an AVF. There were significantly more PCNA-positive cells, SM22α/PCNA-positive cells, collagen I deposition, and increased Krüppel-like Factor 2 immunoreactivity in hypertensive mice with an AVF compared with normotensive mice with an AVF.

Conclusions

These data show that a central AVF decreases systemic hypertension as well as induces local alterations in venous remodeling.

Angiotensin-converting enzyme 2 alleviates liver fibrosis through the renin-angiotensin system

The present letter to the editor is related to the study titled 'Angiotensin-converting enzyme 2 improves liver fibrosis in mice by regulating autophagy of hepatic stellate cells'. Angiotensin-converting enzyme 2 can alleviate liver fibrosis by regulating autophagy of hepatic stellate cells and affecting the renin-angiotensin system.

Blockade of angiotensin II modulates insulin-like growth factor 1-mediated skeletal muscle homeostasis in experimental steatohepatitis

Sarcopenia is associated with mortality in patients with nonalcoholic steatohepatitis (NASH). Angiotensin II receptor blocker (ARB) has been suggested to prevent sarcopenia, but reports on its effect on NASH-derived skeletal muscle atrophy in conjunction with insulin-like growth factor 1 (IGF-1)-mediated muscle homeostasis are few. Our aim was to examine the combined effect of the ARB losartan and IGF-1 replacement on skeletal muscle atrophy in a methionine-choline deficient (MCD) diet-fed murine steatohepatitis model. The MCD-fed mice developed steatohepatitis and skeletal muscle atrophy, as indicated by the reduction of psoas muscle mass and attenuation of forelimb and hindlimb grip strength. Significantly suppressed steatohepatitis and skeletal muscle atrophy was observed after single treatment with ARB or IGF-1, and these effects were augmented after combination treatment. Treatment with ARB and IGF-1 effectively inhibited ubiquitin proteasome-mediated protein degradation by reducing forkhead box protein O1 (FOXO1) and FOXO3a transcriptional activity in the skeletal muscle. Combined ARB and IGF-1 decreased the intramuscular expression of proinflammatory cytokines (i.e., TNFα, IL6, and IL1β) and increased the Trolox equivalent antioxidant capacity and antioxidant enzymes (CAT, GPX1, SOD2, and CYTB). This antioxidant effect was based on downregulation of NADPH oxidase (NOX) 2, normalization of mitochondrial biogenesis and dynamics. Moreover, ARB increased the hepatic and plasma IGF-1 levels and improved steatohepatitis, leading to enhanced skeletal muscle protein synthesis mediated by IGF-1/ AKT/ mechanistic target of rapamycin signaling. Collectively, combined ARB and IGF-1 replacement could be a promising new therapeutic target for NASH-derived skeletal muscle wasting.

Dapagliflozin attenuates renal fibrosis by suppressing angiotensin II/TGFβ signaling in diabetic mice

AIMS

Diabetic nephropathy (DN) complicates diabetes Mellitus and intimately relates to intrarenal renin-angiotensin system (RAS) activity. Dapagliflozin, a selective inhibitor of sodium-glucose cotransporter 2 (SGLT2), has been validated to improve renal outcomes in diabetic patients from clinical research by elusive mechanisms. This study explored the presumption that the eagerness activity of intrarenal RAS in DN generated oxidative stress to promote renal fibrosis, and the process can be interrupted by dapagliflozin.

METHODS

A streptozotocin-induced DN model was established in male C57BL/6J mice. Mice were treated with dapagliflozin or losartan for 14 weeks. Biochemical data, renal fibrosis, oxidative stress, and RAS were measured.

RESULTS

DN mice were characterized by overtly low body weight, high levels of blood glucose, and renal injury. Interrupting SGLT2 and RAS significantly improved renal dysfunction and pathological lesions in DN mice. Consistent with these favorable effects, dapagliflozin revoked the local RAS/oxidative stress and the succeeding transforming growth factor beta (TGFβ) signaling.

CONCLUSIONS

This research clarifies that intrarenal RAS activity triggers renal injury in DN, and dapagliflozin attenuates renal fibrosis by suppressing Angiotensin II/TGFβ signaling. It unravels a novel insight into the role of prevention and treatment of SGLT2 inhibitors to DN.

Angiotensin II constricts mouse iliac arteries: possible mechanism for aortic aneurysms

Abdominal aortic aneurysms (AAA) result from maladaptive remodeling of the vascular wall and reduces structural integrity. Angiotensin II (AngII) infusion has become a standard laboratory model for studying AAA initiation and progression. We determined the different vasoactive responses of various mouse arteries to Ang II. Ex vivo isometric tension analysis was conducted on 18-week-old male C57BL/6 mice (n = 4) brachiocephalic arteries (BC), iliac arteries (IL), and abdominal (AA) and thoracic aorta (TA). Arterial rings were mounted between organ hooks, gently stretched and an AngII dose response was performed. Rings were placed in 4% paraformaldehyde for immunohistochemistry analysis to quantify peptide expression of angiotensin type 1 (AT1R) and 2 receptors (AT2R) in the endothelium, media, and adventitia. Results from this study demonstrated vasoconstriction responses in IL were significantly higher at all AngII doses when compared to BC, and TA and AA responses (maximum constriction-IL: 68.64 ± 5.47% vs. BC: 1.96 ± 1.00%; TA: 3.13 ± 0.16% and AA: 2.75 ± 1.77%, p < 0.0001). Expression of AT1R was highest in the endothelium of IL (p < 0.05) and in the media and (p < 0.05) adventitia (p < 0.05) of AA. In contrast, AT2R expression was highest in endothelium (p < 0.05), media (p < 0.01, p < 0.05) and adventitia of TA. These results suggest that mouse arteries display different vasoactive responses to AngII, and the exaggerated response in IL arteries may play a role during AAA development.

Antihypertensive treatment of end-stage renal disease patients on hemodialysis does not alter circulating ACE and ACE2 activity and angiotensin peptides

Cardiovascular diseases (CVD) are the main causes of death in hemodialysis patients, representing a public health challenge. We investigated the effect of different antihypertensive treatments on circulating levels of renin-angiotensin system (RAS) components in end-stage renal disease (ESRD) patients on hemodialysis. ESRD patients were grouped following the prescribed antihypertensive drugs: ß-blocker, ß-blocker+ACEi and ß-blocker+AT1R blocker. ESDR patients under no antihypertensive drug treatment were used as controls. Blood samples were collected before hemodialysis sessions. Enzymatic activities of the angiotensin-converting enzymes ACE and ACE2 were measured through fluorescence assays and plasma concentrations of the peptides Angiotensin II (Ang II) and Angiotensin-(1-7) [Ang-(1-7)] were quantified using mass spectrometry (LC-MS/MS). ACE activity was decreased only in the ß-blocker+ACEi group compared to the ß-blocker+AT1R, while ACE2 activity did not change according to the antihypertensive treatment. Both Ang II and Ang-(1-7) levels also did not change according to the antihypertensive treatment. We concluded that the treatment of ESRD patients on hemodialysis with different antihypertensive drugs do not alter the circulating levels of RAS components.

Mitochondrial KATP channel-mediated autophagy contributes to angiotensin II-induced vascular dysfunction in mice

BACKGROUND AND AIM

The present study aimed to investigate whether the mitochondrial KATP channel contributes to angiotensin II (Ang II)-induced vascular dysfunction, the development of hypertension, and atherosclerosis.

METHODS AND RESULTS

ApoE (-/-) mice fed a high-fat diet were chronically infused with Ang II for eight weeks and concomitantly treated with losartan (ARB), apocynin, or 5-hydroxy decanoate (5-HD), or 3-methyladenine (3-MA). Systolic blood pressure was measured, and pathological changes of aortic or liver tissue were observed. Nitric oxide (NO), superoxide dismutase 2 (SOD2) levels and vasorelaxation rate were measured, and protein and mRNA expressions were examined by western blot and RT-PCR. Ang II-induced development of hypertension was suppressed not only by ARB, and apocynin but also by 5-HD or 3-MA. Ang II infusion decreased aortic NO production and relaxation, as well as SOD2 activity in liver, which were improved by all treatments. In addition, Ang II-induced activation of autophagy was suppressed by 5-HD in aortic tissue, furthermore, Ang II increases the atherosclerotic index in plasma and exacerbates the development of atherosclerosis by increases of fat deposition in the aorta and liver. Lipid metabolism-related mRNA expressions (LXR-α, LDLR, SRBI, Acca, and FASN) were changed by Ang II. Similarly, not only ARB, and apocynin, but also 5-HD and 3-MA suppressed Ang II-induced these changes.

CONCLUSIONS

Our present findings evidence that mitochondrial KATP channel-mediated autophagy contributes to Ang II-induced vascular dysfunction, development of hypertension, and atherosclerosis.

α-Ketoglutarate improves cardiac insufficiency through NAD+-SIRT1 signaling-mediated mitophagy and ferroptosis in pressure overload-induced mice

BACKGROUND

In heart failure (HF), mitochondrial dysfunction and metabolic remodeling lead to a reduction in energy productivity and aggravate cardiomyocyte injury. Supplementation with α-ketoglutarate (AKG) alleviated myocardial hypertrophy and fibrosis in mice with HF and improved cardiac insufficiency. However, the myocardial protective mechanism of AKG remains unclear. We verified the hypothesis that AKG improves mitochondrial function by upregulating NAD+ levels and activating silent information regulator 2 homolog 1 (SIRT1) in cardiomyocytes.

METHODS

In vivo, 2% AKG was added to the drinking water of mice undergoing transverse aortic constriction (TAC) surgery. Echocardiography and biopsy were performed to evaluate cardiac function and pathological changes. Myocardial metabolomics was analyzed by liquid chromatography‒mass spectrometry (LC‒MS/MS) at 8 weeks after surgery. In vitro, the expression of SIRT1 or PINK1 proteins was inhibited by selective inhibitors and siRNA in cardiomyocytes stimulated with angiotensin II (AngII) and AKG. NAD+ levels were detected using an NAD test kit. Mitophagy and ferroptosis levels were evaluated by Western blotting, qPCR, JC-1 staining and lipid peroxidation analysis.

RESULTS

AKG supplementation after TAC surgery could alleviate myocardial hypertrophy and fibrosis and improve cardiac function in mice. Metabolites of the malate-aspartate shuttle (MAS) were increased, but the TCA cycle and fatty acid metabolism pathway could be inhibited in the myocardium of TAC mice after AKG supplementation. Decreased NAD+ levels and SIRT1 protein expression were observed in heart of mice and AngII-treated cardiomyocytes. After AKG treatment, these changes were reversed, and increased mitophagy, inhibited ferroptosis, and alleviated damage in cardiomyocytes were observed. When the expression of SIRT1 was inhibited by a selective inhibitor and siRNA, the protective effect of AKG was suppressed.

CONCLUSION

Supplementation with AKG can improve myocardial hypertrophy, fibrosis and chronic cardiac insufficiency caused by pressure overload. By increasing the level of NAD+, the SIRT-PINK1 and SIRT1-GPX4 signaling pathways are activated to promote mitophagy and inhibit ferroptosis in cardiomyocytes, which ultimately alleviates cardiomyocyte damage.

Angiotensin II and post-streptococcal glomerulonephritis

BACKGROUND

Post-streptococcal glomerulonephritis (PSGN) is a consequence of the infection by group A beta-hemolytic streptococcus. During this infection, various immunological processes generated by streptococcal antigens are triggered, such as the induction of antibodies and immune complexes. This activation of the immune system involves both innate and acquired immunity. The immunological events that occur at the renal level lead to kidney damage with chronic renal failure as well as resolution of the pathological process (in most cases). Angiotensin II (Ang II) is a molecule with vasopressor and pro-inflammatory capacities, being an important factor in various inflammatory processes. During PSGN some events are defined that make Ang II conceivable as a molecule involved in the inflammatory processes during the disease.

CONCLUSION

This review is focused on defining which reported events would be related to the presence of this hormone in PSGN.

A randomised clinical trial study assessing the efficacy of 5% losartan potassium loaded in ethosomal gel to treat human keloids: a trial protocol

BACKGROUND

Keloid is a skin disorder that results from excessive fibrous tissue growth in the area of the initial trauma. Treating keloids can be challenging since the success of various treatments varies from one study to another. Triamcinolone acetonide injection, a standard treatment, can cause undesirable side effects. Meanwhile, the effectiveness of existing topical therapies for keloids is not always reliable. The pro-inflammatory, pro-proliferative, and pro-fibrotic effects of angiotensin II in human skin contribute to keloid formation. Losartan potassium, an angiotensin II blocker, has the potential to act as an anti-keloid agent. Due to the thicker skin structure of a keloid and ease of application, ethosome gel is chosen as a safe and comfortable carrier for losartan potassium, making it a good choice for treating keloids.

METHODS

In this randomised clinical trial, 46 adults with keloids were divided into two treatment groups. One group of 23 participants received 5% losartan potassium loaded in ethosomal gel, while the other group of 23 participants received intralesional injections of 10% triamcinolone acetonide. Over 12 weeks, changes in POSAS 3.0 scores, degree of erythema and pigmentation, surface area, thickness, and pliability of the keloids will be measured at four different times: baseline, 4 weeks, 8 weeks, and 12 weeks. Statistical analysis will be conducted using SPSS software version 24, with a significance level of p < 0.05.

DISCUSSION

Losartan potassium is believed to be beneficial for keloid management because it inhibits the angiotensin II receptor, which plays a role in inflammation, proliferation, and fibrosis. This study examines the efficacy of 5% losartan potassium loaded in ethosomal gel for human keloids.

TRIAL REGISTRATION

Clinicaltrial.gov identifier NCT05893108 . Registered on 7 June 2023.

Higher Neuronal Facilitation and Potentiation with APOE4 Suppressed by Angiotensin II

Progressive hippocampal degeneration is a key component of Alzheimer's disease (AD) progression. Therefore, identifying how hippocampal neuronal function is modulated early in AD is an important approach to eventually prevent degeneration. AD-risk factors and signaling molecules likely modulate neuronal function, including APOE genotype and angiotensin II. Compared to APOE3, APOE4 increases AD risk up to 12-fold, and high levels of angiotensin II are hypothesized to disrupt neuronal function in AD. However, the extent that APOE and angiotensin II modulates the hippocampal neuronal phenotype in AD-relevant models is unknown. To address this issue, we used electrophysiological techniques to assess the impact of APOE genotype and angiotensin II on basal synaptic transmission, presynaptic, and post-synaptic activity in mice that express human APOE3 (E3FAD) or APOE4 (E4FAD) and overproduce Aβ. We found that compared to E3FAD mice, E4FAD mice have lower synaptic activity, but higher levels of paired-pulse facilitation (PPF) and long-term potentiation (LTP) in the Schaffer Collateral Commissural Pathway (SCCP) of the hippocampus. We also found that exogenous angiotensin II has a profound inhibitory effect on hippocampal LTP in both E3FAD and E4FAD mice. Collectively, our data suggests that APOE4 and Aβ are associated with a hippocampal phenotype comprised of lower basal activity and higher responses to high-frequency stimulation, the latter of which is suppressed by angiotensin II. These novel data suggest a potential mechanistic link between hippocampal activity, APOE4 genotype, and angiotensin II in AD.

Orexin deficiency modulates the dipsogenic effects of angiotensin II in a sex-dependent manner

The orexin (hypocretin) neuropeptide system is an important regulator of ingestive behaviors, i.e., it promotes food and water intake. Here, we investigated the role of orexin in drinking induced by the potent dipsogen angiotensin II (ANG II). Specifically, male and female orexin-deficient mice received intracerebroventricular (ICV) injections of ANG II, followed by measuring their water intake within 15 min. We found that lower doses of ANG II (100 ng) significantly stimulated drinking in males but not in females, indicating a general sex-dependent effect that was not affected by orexin deficiency. However, higher doses of ANG II (500 ng) were sufficient to induce drinking in female wild-type mice, while female orexin-deficient mice still did not respond to the dipsogenic properties of ANG II. In conclusion, these results suggest sex-dependent effects in ANG II-induced drinking and further support the sexual dimorphism of orexin system functions.

Deletion of vascular thromboxane A2 receptors and its impact on angiotensin II-induced hypertension and atherosclerotic lesion formation in the aorta of Ldlr-deficient mice

The thromboxane A2 receptor (TP) has been shown to play a role in angiotensin II (Ang II)-mediated hypertension and pathological vascular remodeling. To assess the impact of vascular TP on Ang II-induced hypertension, atherogenesis, and pathological aortic alterations, i.e. aneurysms, we analysed Western-type diet-fed and Ang II-infused TPVSMC KO/Ldlr KO, TPEC KO/Ldlr KO mice and their respective wild-type littermates (TPWT/Ldlr KO). These analyses showed that neither EC- nor VSMC-specific deletion of the TP significantly affected basal or Ang II-induced blood pressure or aortic atherosclerotic lesion area. In contrast, VSMC-specific TP deletion abolished and EC-specific TP deletion surprisingly reduced the ex vivo reactivity of aortic rings to the TP agonist U-46619, whereas VSMC-specific TP knockout also diminished the ex vivo response of aortic rings to Ang II. Furthermore, despite similar systemic blood pressure, there was a trend towards less atherogenesis in the aortic arch and a trend towards fewer pathological aortic alterations in Ang II-treated female TPVSMC KO/Ldlr KO mice. Survival was impaired in male mice after Ang II infusion and tended to be higher in TPVSMC KO/Ldlr KO mice than in TPWT/Ldlr KO littermates. Thus, our data may suggest a deleterious role of the TP expressed in VSMC in the pathogenesis of Ang II-induced aortic atherosclerosis in female mice, and a surprising role of the endothelial TP in TP-mediated aortic contraction. However, future studies are needed to substantiate and further elucidate the role of the vascular TP in the pathogenesis of Ang II-induced hypertension, aortic atherosclerosis and aneurysm formation.

Costunolide ameliorates angiotensin II-induced atrial inflammation and fibrosis by regulating mitochondrial function and oxidative stress in mice: A possible therapeutic approach for atrial fibrillation

Atrial fibrillation (AF) is a cardiac disease characterized by disordered atrial electrical activity. Atrial inflammation and fibrosis are involved in AF progression. Costunolide (COS) is a sesquiterpene lactone containing anti-inflammatory and anti-fibrotic activities. This study aims to explore the underlying mechanisms by which COS protects against AF. Male C57BL/6 mice (8- to 10-week-old) were infused with angiotensin (Ang) II for 3 weeks. Meanwhile, different doses of COS (COS-L: 10 mg/kg, COS-H: 20 mg/kg) were administered to mice by intragastric treatment. The results showed irregular and rapid heart rates in Ang II-treated mice. Moreover, the levels of inflammatory cytokines and fibrotic factors were elevated in mice. COS triggered a reduction of Ang II-induced inflammation and fibrosis, which conferred a protective effect. Mechanistically, mitochondrial dysfunction with mitochondrial respiration inhibition and aberrant ATP levels were observed after Ang II treatment. Moreover, Ang-II-induced excessive reactive oxygen species caused oxidative stress, which was further aggravated by inhibiting Nrf2 nuclear translocation. Importantly, COS diminished these Ang-II-mediated effects in mice. In conclusion, COS attenuated inflammation and fibrosis in Ang-II-treated mice by alleviating mitochondrial dysfunction and oxidative stress. Our findings represent a potential therapeutic option for AF treatment.

Glucagon-Like Peptide Receptor Agonist Inhibits Angiotensin II-Induced Proliferation and Migration in Vascular Smooth Muscle Cells and Ameliorates Phosphate-Induced Vascular Smooth Muscle Cells Calcification

BACKGRUOUND

Glucagon-like peptide-1 receptor agonist (GLP-1RA), which is a therapeutic agent for the treatment of type 2 diabetes mellitus, has a beneficial effect on the cardiovascular system.

METHODS

To examine the protective effects of GLP-1RAs on proliferation and migration of vascular smooth muscle cells (VSMCs), A-10 cells exposed to angiotensin II (Ang II) were treated with either exendin-4, liraglutide, or dulaglutide. To examine the effects of GLP-1RAs on vascular calcification, cells exposed to high concentration of inorganic phosphate (Pi) were treated with exendin-4, liraglutide, or dulaglutide.

RESULTS

Ang II increased proliferation and migration of VSMCs, gene expression levels of Ang II receptors AT1 and AT2, proliferation marker of proliferation Ki-67 (Mki-67), proliferating cell nuclear antigen (Pcna), and cyclin D1 (Ccnd1), and the protein expression levels of phospho-extracellular signal-regulated kinase (p-Erk), phospho-c-JUN N-terminal kinase (p-JNK), and phospho-phosphatidylinositol 3-kinase (p-Pi3k). Exendin-4, liraglutide, and dulaglutide significantly decreased the proliferation and migration of VSMCs, the gene expression levels of Pcna, and the protein expression levels of p-Erk and p-JNK in the Ang II-treated VSMCs. Erk inhibitor PD98059 and JNK inhibitor SP600125 decreased the protein expression levels of Pcna and Ccnd1 and proliferation of VSMCs. Inhibition of GLP-1R by siRNA reversed the reduction of the protein expression levels of p-Erk and p-JNK by exendin-4, liraglutide, and dulaglutide in the Ang II-treated VSMCs. Moreover, GLP-1 (9-36) amide also decreased the proliferation and migration of the Ang II-treated VSMCs. In addition, these GLP-1RAs decreased calcium deposition by inhibiting activating transcription factor 4 (Atf4) in Pi-treated VSMCs.

CONCLUSION

These data show that GLP-1RAs ameliorate aberrant proliferation and migration in VSMCs through both GLP-1Rdependent and independent pathways and inhibit Pi-induced vascular calcification.

Angiotensin II-induced vascular endothelial cells ferroptosis via P53-ALOX12 signal axis

OBJECTIVES

The present study aimed to investigate the effect and mechanism of angiotensin II-induced ferroptosis in vascular endothelial cells.

METHODS

In vitro, HUVECs were treated with AngII, AT_1/2 R antagonist, P53 inhibitor, or their combinations. MDA and intracellular iron content were evaluated using an ELISA assay. The expression of ALOX12, P53, P21, and SLC7A11 were determined by western blotting in HUVECs and then confirmed through RT-PCR.

RESULTS

As the concentration of Ang II (0, 0.1,1,10,100, and 1000uM for 48 h) increased, the level of MDA and intracellular iron content increased in HUVECs. Compared with the single AngII group, ALOX12, p53, MDA, and intracellular iron content in AT_1/2R antagonist group decreased significantly. In pifithrin-α hydrobromide-treated, ALOX12, P21,MDA, and intracellular iron content decreased significantly as compared to the single AngII group. Similarly, the effect of combined use of blockers is stronger than that of blockers alone.

CONCLUSIONS

AngII can induce ferroptosis of vascular endothelial cells. The mechanism of AngII-induced ferroptosis may be regulated through the signal axis of p53-ALOX12.

20(S)-ginsenoside Rh2 inhibits angiotensin-2 mediated cardiac remodeling and inflammation associated with suppression of the JNK/AP-1 pathway

BACKGROUND

Enhanced levels of angiotensin-2 (Ang-II) causes hypertensive heart failure (HHF) through non-hemodynamical and hemodynamical alterations. 20(S)-ginsenoside Rh2 (20(S)-Rh2) is a natural ginseng compound with numerous cardiovascular benefits. This investigation elucidates the influence of 20(S)-Rh2 on Ang-II-induced heart failure and cardiac alterations.

METHODS

Ang-II was administered in C57BL/6 mice for 4 weeks to induce HHF. In the last 2 weeks of treatment, 20(S)-Rh2 was orally administered in mice to assess the potential 20(S)-Rh2 mechanism. Subsequently, RNA sequencing was carried out.

RESULTS

It was indicated that 20(S)-Rh2 suppresses myocardial fibrosis, hypertrophy, and inflammation, thereby inhibiting cardiac disruption in Ang-II-challenged mice without affecting blood pressure. According to the RNA sequencing data, this cardio-protective effect was linked with the (JNK)/AP 1 pathway. 20(S)-Rh2 alleviated heart tissue and cardiomyocytes inflammation by inhibiting the Ang-II-mediated JNK/AP-1 pathway. Within cardiomyocytes, JNK or AP-1 absence abolished the anti-inflammatory effects of 20(S)-Rh2.

CONCLUSION

This study investigation indicated that 20(S)-Rh2 prevents cardiovascular dysfunction induced by Ang-II induced by decreasing JNK-regulated inflammatory responses, providing evidence for its use as an efficient regimen for HHF.

Muscone inhibits angiotensin II-induced cardiac hypertrophy through the STAT3, MAPK and TGF-β/SMAD signaling pathways

BACKGROUND

Muscone is a chemical monomer derived from musk. Although many studies have confirmed the cardioprotective effects of muscone, the effects of muscone on cardiac hypertrophy and its potential mechanisms are unclear.The aim of the present study was to investigate the effect of muscone on angiotensin (Ang) II-induced cardiac hypertrophy.

METHODS AND RESULTS

In the present study, we found for the first time that muscone exerted inhibitory effects on Ang II-induced cardiac hypertrophy and cardiac injury in mice. Cardiac function was analyzed by echocardiography measurement, and the degree of cardiac fibrosis was determined by the quantitative real-time polymerase chain reaction (qRT-PCR), Masson trichrome staining and western blot assay. Secondly, qRT-PCR experiment showed that muscone attenuated cardiac injury by reducing the secretion of pro-inflammatory cytokines and promoting the secretion of anti-inflammatory cytokines. Moreover, western blot analysis found that muscone exerted cardio-protective effects by inhibiting phosphorylation of key proteins in the STAT3, MAPK and TGF-β/SMAD pathways. In addition, CCK-8 and determination of serum biochemical indexes showed that no significant toxicity or side effects of muscone on normal cells and organs.

CONCLUSIONS

Muscone could attenuate Ang II-induced cardiac hypertrophy, in part, by inhibiting the STAT3, MAPK, and TGF-β/SMAD signaling pathways.

Dose-dependent regulation of kidney mitochondrial function by angiotensin II

Background

Intrarenal hypoxia has been suggested a unifying pathway to chronic kidney disease (CKD) and increased mitochondria leak respiration, which increases mitochondrial oxygen usage and is one important mechanism contributing to the development of the hypoxia. Previous studies indicate that angiotensin II (Ang II) effects on mitochondria function could be dose dependent. We investigated how moderate and high levels of Ang II affect kidney mitochondria function and pathways of leak respiration.

Methods

C57 black 6 mice were treated with either vehicle or Ang II in low dose (400 ng/kg/min) or high dose (1,000 ng/kg/min) for 4 weeks. The function of kidney cortex mitochondria was measured by high-resolution respirometry. Ang II effects on gene expression in kidney tissue were measured by quantitative real-time PCR. Thiobarbituric acids reactive substances were determined as a marker of oxidative stress, and urinary protein excretion was measured as a maker of kidney injury.

Results

Low-dose Ang II induced overall mitochondria respiration, without compromising capacity of ATP production. Mitochondrial leak respiration was increased, and levels of oxidative stress were unchanged. However, high-dose Ang II decreased overall mitochondria respiration and reduced mitochondrial capacity for ATP production. Mitochondrial leak respiration was decreased, and oxidative stress increased in kidney tissue. Furthermore, gene expression of mediators that stimulate vasoconstriction and ROS production was increased, while components of counteracting pathways were decreased.

Conclusions

In conclusion, Ang II dose-dependently affects mitochondrial function and leak respiration. Thus, Ang II has the potential to directly affect cellular metabolism during conditions of altered Ang II signaling.

Angiotensin II treatment is associated with improved oxygenation in ARDS patients with refractory vasodilatory shock

BACKGROUND

The physiological effects of renin-angiotensin system modulation in acute respiratory distress syndrome (ARDS) remain controversial and have not been investigated in randomized trials. We sought to determine whether angiotensin-II treatment is associated with improved oxygenation in shock-associated ARDS.

METHODS

Post-hoc subgroup analysis of the Angiotensin Therapy for High Output Shock (ATHOS-3) trial. We studied patients who met modified Berlin ARDS criteria at enrollment. The primary outcome was PaO2/FiO2-ratio (P:F) at 48-h adjusted for baseline P:F. Secondary outcomes included oxygenation index, ventilatory ratio, PEEP, minute-ventilation, hemodynamic measures, patients alive and ventilator-free by day-7, and mortality.

RESULTS

Of 81 ARDS patients, 34 (42%) and 47 (58%) were randomized to angiotensin-II or placebo, respectively. In angiotensin-II patients, mean P:F increased from 155 mmHg (SD: 69) at baseline to 265 mmHg (SD: 160) at hour-48 compared with no change with placebo (148 mmHg (SD: 63) at baseline versus 164 mmHg (SD: 74) at hour-48)(baseline-adjusted difference: + 98.4 mmHg [95%CI 35.2-161.5], p = 0.0028). Similarly, oxygenation index decreased by - 6.0 cmH2O/mmHg at hour-48 with angiotensin-II versus - 0.4 cmH2O/mmHg with placebo (baseline-adjusted difference: -4.8 cmH2O/mmHg, [95%CI - 8.6 to - 1.1], p = 0.0273). There was no difference in PEEP, minute ventilation, or ventilatory ratio. Twenty-two (64.7%) angiotensin-II patients had sustained hemodynamic response to treatment at hour-3 versus 17 (36.2%) placebo patients (absolute risk-difference: 28.5% [95%CI 6.5-47.0%], p = 0.0120). At day-7, 7/34 (20.6%) angiotensin-II patients were alive and ventilator-free versus 5/47(10.6%) placebo patients. Day-28 mortality was 55.9% in the angiotensin-II group versus 68.1% in the placebo group.

CONCLUSIONS

In post-hoc analysis of the ATHOS-3 trial, angiotensin-II was associated with improved oxygenation versus placebo among patients with ARDS and catecholamine-refractory vasodilatory shock. These findings provide a physiologic rationale for trials of angiotensin-II as treatment for ARDS with vasodilatory shock.

TRIAL REGISTRATION

ClinicalTrials.Gov Identifier: NCT02338843 (Registered January 14th 2015).

PFKFB3 downregulation aggravates Angiotensin II-induced podocyte detachment

Podocytes play a critical role in maintaining normal glomerular filtration, and podocyte loss from the glomerular basement membrane (GBM) initiates and worsens chronic kidney disease (CKD). However, the exact mechanism underlying podocyte loss remains unclear. Fructose-2,6-biphosphatase 3 (PFKFB3) is a bifunctional enzyme that plays crucial roles in glycolysis, cell proliferation, cell survival, and cell adhesion. This study aimed to determine the role of PFKFB3 in angiotensin II (Ang II) kidney damage. We found that mice infused with Ang II developed glomerular podocyte detachment and impaired renal function accompanied by decreased PFKFB3 expression in vivo and in vitro. Inhibition of PFKFB3 with the PFKFB3 inhibitor 3PO further aggravated podocyte loss induced by Ang II. In contrast, activating PFKFB3 with the PFKFB3 agonist meclizine alleviated the podocyte loss induced by Ang II. Mechanistically, PFKFB3 knockdown likely aggravate Ang II-induced podocyte loss by suppressing talin1 phosphorylation and integrin beta1 subunit (ITGB1) activity. Conversely, PFKFB3 overexpression protected against Ang II-induced podocyte loss. These findings suggest that Ang II leads to a decrease in podocyte adhesion by suppressing PFKFB3 expression, and indicates a potential therapeutic target for podocyte injury in CKD.

Angiotensin II induces endothelial dysfunction and vascular remodeling by downregulating TRPV4 channels

Angiotensin II (Ang II) is a potent vasoconstrictor of vascular smooth muscle cells (VSMC) and is implicated in hypertension, but it's role in the regulation of endothelial function is not well known. We and others have previously shown that mechanically activated ion channel, Transient Receptor Potential Vanilloid 4 (TRPV4) mediates flow- and/or receptor-dependent vasodilation via nitric oxide (NO) production in endothelial cells. Ang II was demonstrated to crosstalk with TRPV4 via angiotensin 1 receptor (AT1R) and β-arrestin signaling in epithelial and immortalized cells, however, the role of this crosstalk in endothelial cell function is not fully explored. Ang II treatment significantly downregulated TRPV4 protein expression and TRPV4-mediated Ca2+ influx in human EC without altering TRPV4 mRNA levels. Further, TRPV4-induced eNOS phosphorylation and NO production were significantly reduced in Ang II-treated human EC. Importantly, Ang II infusion in mice revealed that, TRPV4/p-eNOS expression and colocalization was reduced in endothelium in vivo. Finally, Ang II infusion induced vascular remodeling as evidenced by decreased lumen to wall ratio in resistant mesenteric arteries. These findings suggest that Ang II induces endothelial dysfunction and vascular remodeling via downregulation of TRPV4/eNOS pathway and may contribute to hypertension, independent of or in addition to its effect on vascular smooth muscle contraction.

Cisplatin treatment reduces contraction to angiotensin II by altering expression of angiotensin II receptors: a pilot study

The renin angiotensin system is a key regulator of blood pressure homeostasis. Angiotensin type 1 (AT1R) and 2 receptors (AT2R) have been investigated as targets for cisplatin-induced acute kidney injury; however, their therapeutic potential remains inconclusive. This pilot study aimed to determined the effect that acute cisplatin treatment had on angiotensin II (AngII)-induced contraction in blood vessels and expression profiles of AT1R and AT2R in mouse arteries and kidneys. Male C57BL/6 mice at 18 week of age (n = 8) were treated with vehicle or bolus dose of cisplatin (12.5 mg/kg). Thoracic aorta (TA), adnominal aorta (AA), brachiocephalic arteries (BC), iliac arteries (IL) and kidneys were collected for isometric tension and immunohistochemistry analysis. Cisplatin treatment reduced IL contraction to AngII at all doses (p < 0.01, p < 0.001, p < 0.0001); however, AngII did not induce contraction in TA, AA or BC in either treatment group. Following cisplatin treatment, AT1R expression was significantly upregulated in the media of TA (p < 0.0001) and AA (p < 0.0001), and in the endothelium (p < 0.05) media (p < 0.0001) and adventitia (p < 0.01) of IL. Cisplatin treatment significantly reduced AT2R expression in the endothelium (p < 0.05) and media (p < 0.05) of TA. In renal tubules, both AT1R (p < 0.01) and AT2R (p < 0.05) were increased following cisplatin treatment. Herein, we report that cisplatin reduces AngII-mediated contraction in IL and may be explained by an absence of normal counterregulatory expression of AT1R and AT2R, indicating other factors are involved.

Insulin augments angiotensin II-induced myocardial fibrosis via the MEK/STAT3 pathway

Regular insulin therapy is significantly related to worse cardiovascular outcomes in patients with type 2 diabetes and heart failure. However, the mechanisms of the causal relationship remain unclear. In this study, we observed the effect of insulin on cardiac structure and function and found that insulin dramatically augmented angiotensin II (Ang II)-induced cardiac dysfunction, as well as the proliferation and collagen production of primary cardiac fibroblasts. Total STAT3 expression, but not activation was stimulated by insulin; the effect of insulin on Ang II-induced fibrosis disappeared when STAT3 was blocked and could be entirely suppressed by the MEK inhibitor PD0325901. Our findings suggest a noninsulin-dependent glucose-lowering regimen for patients with type 2 diabetes (T2DM) and heart failure (HF).

The alternative renin-angiotensin system in critically ill patients: pathophysiology and therapeutic implications

The renin-angiotensin system (RAS) plays a crucial role in regulating blood pressure and the cardio-renal system. The classical RAS, mainly mediated by angiotensin I, angiotensin-converting enzyme, and angiotensin II, has been reported to be altered in critically ill patients, such as those in vasodilatory shock. However, recent research has highlighted the role of some components of the counterregulatory axis of the classical RAS, termed the alternative RAS, such as angiotensin-converting Enzyme 2 (ACE2) and angiotensin-(1-7), or peptidases which can modulate the RAS like dipeptidyl-peptidase 3, in many critical situations. In cases of shock, dipeptidyl-peptidase 3, an enzyme involved in the degradation of angiotensin and opioid peptides, has been associated with acute kidney injury and mortality and preclinical studies have tested its neutralization. Angiotensin-(1-7) has been shown to prevent septic shock development and improve outcomes in experimental models of sepsis. In the context of experimental acute lung injury, ACE2 activity has demonstrated a protective role, and its inactivation has been associated with worsened lung function, leading to the use of active recombinant human ACE2, in preclinical and human studies. Angiotensin-(1-7) has been tested in experimental models of acute lung injury and in a recent randomized controlled trial for patients with COVID-19 related hypoxemia. Overall, the alternative RAS appears to have a role in the pathogenesis of disease in critically ill patients, and modulation of the alternative RAS may improve outcomes. Here, we review the available evidence regarding the methods of analysis of the RAS, pathophysiological disturbances of this system, and discuss how therapeutic manipulation may improve outcomes in the critically ill.

Angiotensin II in liver transplantation (AngLT-1): protocol of a randomised, double-blind, placebo-controlled trial

INTRODUCTION

Catecholamine vasopressors such as norepinephrine are the standard drugs used to maintain mean arterial pressure during liver transplantation. At high doses, catecholamines may impair organ perfusion. Angiotensin II is a peptide vasoconstrictor that may improve renal perfusion pressure and glomerular filtration rate, a haemodynamic profile that could reduce acute kidney injury. Angiotensin II is approved for vasodilatory shock but has not been rigorously evaluated for treatment of hypotension during liver transplantation. The objective is to assess the efficacy of angiotensin II as a second-line vasopressor infusion during liver transplantation. This trial will establish the efficacy of angiotensin II in decreasing the dose of norepinephrine to maintain adequate blood pressure. Completion of this study will allow design of a follow-up, multicentre trial powered to detect a reduction of organ injury in liver transplantation.

METHODS AND ANALYSIS

This is a double-blind, randomised clinical trial. Eligible subjects are adults with a Model for End-Stage Liver Disease Sodium Score ≥25 undergoing deceased donor liver transplantation. Subjects are randomised 1:1 to receive angiotensin II or saline placebo as the second-line vasopressor infusion. The study drug infusion is initiated on reaching a norepinephrine dose of 0.05 µg kg-1 min-1 and titrated per protocol. The primary outcome is the dose of norepinephrine required to maintain a mean arterial pressure ≥65 mm Hg. Secondary outcomes include vasopressin or epinephrine requirement and duration of hypotension. Safety outcomes include incidence of thromboembolism within 48 hours of the end of surgery and severe hypertension. An intention-to-treat analysis will be performed for all randomised subjects receiving the study drug. The total dose of norepinephrine will be compared between the two arms by a one-tailed Mann-Whitney U test.

ETHICS AND DISSEMINATION

The trial protocol was approved by the local Institutional Review Board (#20-30948). Results will be posted on ClinicalTrials.gov and published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ClinicalTrials.govNCT04901169.

Salidroside attenuates atrial fibrosis and atrial fibrillation vulnerability induced by angiotensin-II through inhibition of LOXL2-TGF-β1-Smad2/3 pathway

Aims and objectives

Salidroside (SAL), an active component isolated from the Chinese plant Rose Rhodiola, has anti-inflammatory, antioxidant, anti-cancer, neuroprotective, and renal protective properties. Atrial fibrosis developed due to angiotensin II (Ang II) plays a crucial function in developing atrial fibrillation (AF). This research investigates the involvement of SAL in AF, its vulnerability to AF, and Ang II-induced inflammatory atrial fibrosis.

Methods

Ang II (2 mg/kg/day) was infused underneath the skin into male C57BL/6 mice (8-10 weeks old, n = 40) for four weeks to create the AF model. SAL (50 mg/kg/day) was given intraperitoneally once per day for 28 days. Analyses of morphology, histology, and biochemical were carried out. Transesophageal burst pacing was used in vivo to induce AF.

Results

Ang II injection increased mice's heart rate and systolic blood pressure (SBP), whereas SAL treatment was significantly reduced. Ang II infusion increased left atrial diameter (LAD) in mice, which was attenuated after SAL treatment. SAL alone did not affect AF inducibility, but SAL therapy markedly decreased Ang II-induced AF inducibility. Additionally, the expression levels of interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were inhibited with SAL therapy in mice. Compared to the Ang II group, Ang II infusion raised malondialdehyde (MDA) levels and reduced superoxide dismutase (SOD) and catalase (CAT) activity, but SAL therapy altered all of these effects. SAL treatment significantly reduced LOXL2, TGF-β1, p-Smad2 and p-Smad3 protein expression than the Ang II group mice.

Conclusion

SAL inhibits atrial fibrosis and potentially attenuates increased susceptibility to AF by suppressing the LOXL2-TGF-β1-Smad2/3 pathway.

Vitamin D deficiency enhances vascular oxidative stress, inflammation, and angiotensin II levels in the microcirculation of diabetic patients

Low vitamin D (vitD) levels have been reported to be a risk factor for diabetes-related cardiovascular complications. This study examined the effects of vitD deficiency on oxidative stress (OS), inflammation, and levels of the vasoconstrictor angiotensin II (Ang II) in the microvascular tissue of type 2 diabetic patients. Patients were categorized into (i) vitD non-deficient diabetics (DNP, n = 10) and (ii) vitD-deficient diabetics (DDP, n = 10), based on their serum 25(OH)D levels. Subcutaneous fat tissues with intact blood vessels were collected during lower limb surgical procedures. The blood vessel were isolated; measurements of the antioxidant enzyme superoxide dismutase (SOD) activity, OS marker malondialdehyde (MDA), Ang II, and the inflammatory marker, TNF-α of the microvascular tissues were determined. Elevated MDA levels and reduced SOD activity, with higher levels of TNF-α and Ang II were observed in the microvascular tissues of DDP compared to DNP. VitD deficiency did not associate with glycemic parameters (fasting blood glucose and glycated hemoglobin) levels. In conclusion, vitD deficiency was correlated with higher microvascular tissue OS, inflammation, and Ang II levels in type 2 diabetic patients. This may contribute to early vasculopathy that occurs in diabetic patients, thus, may contribute to the planning of therapeutic strategies to delay or prevent cardiovascular complications.

The mechanism of oxidative stress in keloid fibroblasts and the experimental study of early application of angiotensin-converting enzyme inhibitor

Objective To investigate the protective effects of an angiotensin-converting enzyme inhibitor after inducing oxidative stress on keloid fibroblasts. Methods Primary keloid fibroblasts were isolated and cultured by enzyme digestion combined with the tissue adhesion method in vitro, and the third to fifth generations of cells were selected for the experiment. For 24 hours, keloid fibroblasts were treated with different concentrations of hydrogen peroxide. Different concentrations of angiotensin-converting enzyme inhibitor were added to the keloid fibroblast culture medium, and then the cells were treated with hydrogen peroxide for 24 hours. Results With the increase of hydrogen peroxide concentration, the growth of keloid fibroblasts was inhibited and the levels of malondialdehyde, superoxide dismutase, and reactive oxygen species increased gradually, accompanied by an increase in the expression of nicotinamide adenine dinucleotide phosphate oxidase and collagen I mRNA. The expression of nicotinamide adenine dinucleotide phosphate oxidase-mRNA in keloid fibroblasts and the formation of reactive oxygen species in keloid fibroblasts were induced by different concentrations of angiotensin II, and the most significant effect was at 10-5 mmol/mL. The effects of diphenyleneiodonium chloride (NOX inhibitor), N-acetylcysteine (reactive oxygen species inhibitor) and nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) RNA treatment on angiotensin II-induced nicotinamide adenine dinucleotide phosphate oxidase and collagen I increased significantly. Hydrogen peroxide and angiotensin II alone or combined can induce NADPH oxidase and reactive oxygen species expression in keloid fibroblasts. When the angiotensin-converting enzyme inhibitor was added, the expression of NADPH oxidase and reactive oxygen species in keloid induced by hydrogen peroxide and angiotensin II could be inhibited. Conclusion Oxidative stress can lead to increased expression of reactive oxygen species, NADPH oxidase and collagen I in keloid fibroblasts, suggesting oxidative stress mediates the migration of human keloid fibroblasts and extracellular matrix synthesis.

Identification of membrane palmitoylated protein 1 (MPP1) as a heart-failure-promoting protein triggered by cardiovascular risk factors and aging

Membrane-Associated Guanylate Kinase (MAGUK) proteins are scaffold proteins with well-established functions in the neuronal system. A role of MAGUK protein up-regulation in the pathogenesis of heart failure is not established. This study identified the up-regulation of the MAGUK family protein MPP1 (Membrane Palmitoylated Protein 1), in cardiac transcriptome data of three different heart failure models. MPP1 was up-regulated in failing hearts of B6 mice with long-term chronic pressure overload, in failing hearts of aged Apoe-/- mice with long-term atherosclerosis, and in failing hearts of RKIP-transgenic mice with cardiotoxic lipid overload. MPP1-transgenic mice revealed that moderately (2-fold) increased cardiac MPP1 levels caused symptoms of heart failure with a significantly reduced left ventricular ejection fraction of 39.0 ± 6.9 % in Tg-MPP1 mice compared to 55.2 ± 3.7 % of non-transgenic B6 controls. Echocardiographic and histological analyses detected cardiac enlargement and cardiac dilation in Tg-MPP1 mice. The angiotensin II AT1 receptor (AGTR1) and MPP1 were co-localized on sarcolemmal membranes in vivo, and Tg-MPP1 mice had increased levels of cardiac AGTR1, which has an established heart failure-promoting function. The increased AGTR1 protein could be directly triggered by elevated MPP1 because MPP1 also increased the AGTR1 protein in non-cardiomyocyte HEK cells, which was detected by fluorescence measurement of AGTR1eYFP. MPP1 was not only up-regulated by major cardiovascular risk factors but also by old age, which is a major contributor to heart failure. Thus, the aging-induced MPP1 exerts a previously unrecognized role in heart failure pathogenesis by upregulation of the angiotensin II AT1 receptor (AGTR1) protein.

AT1 receptors modulate ethanol-induced loss of anticontractile effect of perivascular adipose tissue

Ethanol consumption activates renin-angiotensin-aldosterone system (RAAS), which plays a major role in the pro-contractile and hypertensive effects linked to ethanol. We hypothesized that ethanol consumption induces loss of the anticontractile effect of perivascular adipose tissue (PVAT)through RAAS-mediated mechanisms. We examined the contribution of angiotensin II type 1 receptors (AT1R) to ethanol-induced PVAT dysfunction. With this purpose, male Wistar Hannover rats were treated with ethanol 20 % (in volume ratio) and/or losartan (antagonist of AT1R; 10 mg/kg/day, gavage) for 9 weeks. Losartan prevented the increase in blood pressure and the loss of the anticontractile effect of PVAT induced by ethanol consumption. PVAT dysfunction occurred after 3 and 9 weeks of treatment with ethanol in an endothelium-dependent manner. Blockade of AT1R prevented ethanol-induced reduction of adiponectin levels in PVAT from ethanol-treated rats. Functional assays revealed that ethanol impaired the anticontractile effect of PVAT-derived angiotensin (1-7) and endothelial nitric oxide (NO). In conclusion, AT1R are implicated in ethanol-induced loss of the anticontractile effect of PVAT. In PVAT, AT1R activation decreases the production of adiponectin, a PVAT-derived factor that promotes vasorelaxation in an endothelium-dependent manner. In the endothelium, AT1R favors the production of superoxide (O2•-) leading to a reduction in NO bioavailability. These responses impair the vasodilator action induced by PVAT-derived angiotensin (1-7), which occurs via Mas receptors located in endothelial cells. Ethanol-induced PVAT dysfunction favors vascular hypercontractility, a response that could contribute to the hypertensive state associated with ethanol consumption.

The contribution of the AT1 receptor to erythropoiesis

The renin-angiotensin system (RAS) comprises a broad set of functional peptides and receptors that play a role in cardiovascular homeostasis and contribute to cardiovascular pathologies. Angiotensin II (Ang II) is the most potent peptide hormone produced by the RAS due to its high abundance and its strong and pleiotropic impact on the cardiovascular system. Formation of Ang II takes place in the bloodstream and additionally in tissues in the so-called local RAS. Of the two Ang II receptors (AT1 and AT2) that Ang II binds to, AT1 is the most expressed throughout the mammalian body. AT1 expression is not restricted to cells of the cardiovascular system but in fact AT1 protein is found in nearly all organs, hence, Ang II takes part in several modulatory physiological processes one of which is erythropoiesis. In this review, we present multiple evidence supporting that Ang II modulates physiological and pathological erythropoiesis processes trough the AT1 receptor. Cumulative evidence indicates that Ang II by three distinct mechanisms influences erythropoiesis: 1) stimulation of renal erythropoietin synthesis; 2) direct action on bone marrow precursor cells; and 3) modulation of sympathetic nerve activity to the bone marrow. The text highlights clinical and preclinical evidence focusing on mechanistic studies using rodent models.

Label-free quantitative proteomic analysis of serum exosomes in mice with thoracic aortic aneurysm

OBJECTIVE

Thoracic aortic aneurysm (TAA) is a cardiovascular disease with high morbidity and mortality. However, the causes and mechanisms of TAA are not fully understood. Serum exosomes from mice with TAA were used to explore the markers associated with this disease.

METHODS

C57BL/6 mice were divided into three groups and given ordinary drinking water, ordinary drinking water plus a saline osmotic pump, or drinking water containing β-aminopropionitrile (BAPN) (1 g/kg/d) plus an angiotensin II (Ang II) (1 μg/kg/min) osmotic pump. Haematoxylin and eosin staining of thoracic aortic tissues was performed. The basic characteristics of exosomes were analysed. Differentially expressed proteins (DEPs) were identified by LC‒MS/MS. Protein‒protein networks and enrichment analysis were used to explore possible molecular mechanisms.

RESULTS

The present study elucidated the protein expression profile of serum exosomes in mice with TAA induced by BAPN combined with Ang II. In this work, the expression of a total of 196 proteins was significantly dysregulated in serum exosomes of mice with TAA, with 122 proteins significantly upregulated and 74 proteins markedly downregulated. Notably, Haptoglobin (Hp) and Serum amyloid p-component (Sap) identified based on the PPI network were significantly upregulated and have been strongly linked to cardiovascular disease. Interestingly, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the upregulated and downregulated proteins were involved in the complement and coagulation cascade pathways.

CONCLUSIONS

This study showed that the identified DEPs have potential as biomarkers for the diagnosis of TAA and provided a more comprehensive understanding of the pathophysiological mechanisms of TAA.

Therapeutic targets in the brain for overactive bladder: A focus on angiotensin II type 1 receptor

Overactive bladder is a condition that affects both men and women, and significantly affects patients' quality of life. Anticholinergics, β3-adrenoceptor agonists, and botulinum toxin are currently being used for treatment. However, several patients do not respond to these medications or discontinue them because of adverse events. Angiotensin II (Ang II) is a neuropeptide produced in both brain and peripheral tissues, and Ang II type 1 (AT1) receptors, which are important regions for the micturition reflex, are widely expressed in the cerebral cortex, paraventricular nucleus, solitary tract nucleus, and periaqueductal gray. Our data showed that cumulative central Ang II administration, even at low doses, shortened the intercontraction interval without affecting the blood pressure or blood catecholamine levels. Additionally, Ang II can enhance the micturition reflex by suppressing the GABAergic nervous system and stimulating the downstream pathway of the AT1 receptor. The peripherally administered AT1 receptor blocker telmisartan inhibited central Ang II-induced facilitation of the micturition reflex. Targeting the central AT1 receptor may be a potential treatment approach for patients with overactive bladder. This review introduces the brain AT1 receptor as a therapeutic target in overactive bladder.

MicroRNA-155 mediates endogenous angiotensin II type 1 receptor regulation: implications for innovative type 2 diabetes mellitus management

Type 2 diabetes mellitus (T2DM) is a lifelong condition and a threat to human health. Thorough understanding of its pathogenesis is acutely needed in order to devise innovative, preventative, and potentially curative pharmacological interventions. MicroRNAs (miRNA), are small, non-coding, one-stranded RNA molecules, that can target and silence around 60% of all human genes through translational repression. MiR-155 is an ancient, evolutionarily well-conserved miRNA, with distinct expression profiles and multifunctionality, and a target repertoire of over 241 genes involved in numerous physiological and pathological processes including hematopoietic lineage differentiation, immunity, inflammation, viral infections, cancer, cardiovascular conditions, and particularly diabetes mellitus. MiR-155 Levels are progressively reduced in aging, obesity, sarcopenia, and T2DM. Thus, the loss of coordinated repression of multiple miR-155 targets acting as negative regulators, such as C/EBPβ, HDAC4, and SOCS1 impacts insulin signaling, deteriorating glucose homeostasis, and causing insulin resistance (IR). Moreover, deranged regulation of the renin angiotensin aldo-sterone system (RAAS) through loss of Angiotensin II Type 1 receptor downregulation, and negated repression of ETS-1, results in unopposed detrimental Angiotensin II effects, further promoting IR. Finally, loss of BACH1 and SOCS1 repression abolishes cytoprotective, anti-oxidant, anti-apoptotic, and anti-inflammatory cellular pathways, and promotes β-cell loss. In contrast to RAAS inhibitor treatments that further decrease already reduced miR-155 Levels, strategies to increase an ailing miR-155 production in T2DM, e.g., the use of metformin, mineralocorticoid receptor blockers (spironolactone, eplerenone, finerenone), and verapamil, alone or in various combinations, represent current treatment options. In the future, direct tissue delivery of miRNA analogs is likely.