Activation Of Renin-angiotensin System Research Articles

Poria cocos: traditional uses, triterpenoid components and their renoprotective pharmacology.

Poria cocos and its surface layer of Poria cocos (Schw.) Wolf (Polyporaceae), are used in traditional Chinese medicine for its diuretic and renoprotective effects. Phytochemical studies have shown that lanostane and 3,4-seco-lanostane tetracyclic triterpenoids are the main components of P. cocos and its surface layer. Accumulating evidence shows that triterpenoid components in P. cocos and its surface layer contribute to their renoprotective effect. The surface layer of P. cocos showed a stronger diuretic effect than P. cocos. The ethanol extract of the surface layer and its components improved acute kidney injury, acute kidney injury-to-chronic kidney disease transition and chronic kidney disease such as diabetic kidney disease, nephrotic syndrome and tubulointerstitial nephropathy, and protected against renal fibrosis. It has been elucidated that P. cocos and its surface layer exert a diuretic effect and improve kidney diseases through a variety of molecular mechanisms such as aberrant pathways TGF-β1/Smad, Wnt/β-catenin, IκB/NF-κB and Keap1/Nrf2 signaling as well as the activation of renin-angiotensin system, matrix metalloproteinases, aryl hydrocarbon receptor and endogenous metabolites. These studies further confirm the renoprotective effect of P. cocos and its surface layer and provide a beneficial basis to its clinical use in traditional medicine.

Collecting Duct Pro(Renin) Receptor Contributes to Unilateral Ureteral Obstruction-Induced Kidney Injury via Activation of the Intrarenal RAS.

Although the concept of the intrarenal renin-angiotensin system (RAS) in renal disease is well-described in the literature, the precise pathogenic role and mechanism of this local system have not been directly assessed in the absence of confounding influence from the systemic RAS. The present study used novel mouse models of collecting duct (CD)-specific deletion of (pro)renin receptor (PRR) or renin together with pharmacological inhibition of soluble PRR production to unravel the precise contribution of the intrarenal RAS to renal injury induced by unilateral ureteral obstruction. We examined the impact of CD-specific deletion of PRR, CD-specific deletion of renin, and S1P (site-1 protease) inhibitor PF429242 treatment on renal fibrosis and inflammation and the indices of the intrarenal RAS in a mouse model of unilateral ureteral obstruction. After 3 days of unilateral ureteral obstruction, the indices of the intrarenal RAS including the renal medullary renin content, activity and mRNA expression, and Ang (angiotensin) II content in obstructed kidneys of floxed mice were all increased. That effect was reversed with CD-specific deletion of PRR, CD-specific deletion of renin, and PF429242 treatment, accompanied by consistent improvement in renal fibrosis and inflammation. On the other hand, renal cortical renin levels were unaffected by unilateral ureteral obstruction, irrespective of the genotype. Similar results were obtained via pharmacological inhibition of S1P, the key protease for the generation of soluble PRR. Our results reveal that PRR-dependent/soluble PRR-dependent activation of CD renin represents a key determinant of the intrarenal RAS and, thus, obstruction-induced renal inflammation and fibrosis.

Renin-angiotensin blockade ameliorates the progression of glomerular injury in podocyte-specific Ctcf knockout mice.

Several studies have shown that the progression of proteinuria and renal tissue injury is associated with activation of the intrarenal renin-angiotensin system (RAS). CCCTC-binding factor (CTCF) is a DNA-binding factor that plays an essential role in the regulation of gene expression. In the present study, we aimed to investigate the phenotypic effects of CTCF deficiency in podocytes. Angiotensin II type 1 receptor blockers (ARBs) were administered to the podocyte-specific Ctcf knockout mice, and histological and biochemical analyzes were performed. We also investigated the changes in the expression of podocin in podocyte cell cultures with or without stimulation with angiotensin II from glomeruli isolated using magnetic beads from podocyte-specific Ctcf knockout mice. Mice in which Ctcf was deleted from podocytes developed glomerulopathy and mice developed severe progressive proteinuria, and impaired renal function. Moreover, ARBs suppressed the development of glomerulopathy in podocyte-specific Ctcf knockout mice. Both real-time polymerase chain reaction and western blotting showed that podocin expression was decreased in cell cultures stimulated with angiotensin II. Furthermore, RAS components gene expressions in podocyte cell cultures isolated from podocyte-specific Ctcf knockout mice were significantly increased. These results suggest that RAS is involved in the development of glomerulopathy in podocyte-specific Ctcf knockout mice. Elucidation of the pathophysiology of podocyte-specific Ctcf knockout mice may provide new insights into the relationship between podocyte injury and chronic glomerulonephritis.

Abstract P213: Mechanisms of Renin-Angiotensin System-Mediated Nitric Oxide Signaling in Podocytes

Introduction: The renin-angiotensin system (RAS) is a crucial cardiovascular and renal function regulator. Podocytes, glomerular epithelial cells that play a pivotal role in maintaining the renal filtration barrier, are key targets for RAS peptides. Our findings showed that RAS can promote calcium (Ca 2+ ) and nitric oxide (NO) signaling in podocytes. Moreover, a decrease in NO bioavailability directly correlates with glomerular filtration barrier damage, Ca 2+ overload, and the development of salt-sensitive hypertension. We hypothesized that RAS-mediated NO production is crucial for Ca 2+ control and cytoskeletal rearrangements in podocytes, contributing to glomerular filtration regulation. Methods: We performed live confocal imaging on human podocytes and freshly isolated rat glomeruli to detect the production of NO (DAF-FM) and Ca 2+ (Fluo-8). RAS peptides (Ang II, III, IV, 1-7, 1-9, and TRV120027) were used to stimulate cells, and NO and Ca 2+ production were measured. Blockers for Ang II Type 1 (AT1R), Ang II Type 2 (AT2R), and MAS receptors were used to identify the pathways involved in NO production. The dynamic changes in podocyte cytoskeleton mediated by RAS-NO intracellular signaling were detected using rhodamine-phalloidin staining and scanning ion microscopy. The NOS isoform-specific blockers were used to determine the source of NO in podocytes. ANOVA with post-hoc was used for comparisons. Results: Angiotensins II and III generate the most profound increases in NO levels in podocytes. Ang II, Ang III, and Ang 1-7 promote NO production by activating AT2R (n ≥ 20, p < 0.01). Interestingly, the increase in NO modulates AT1R- and β-arrestin-mediated Ca 2+ signaling (n ≥ 20, p < 0.05), suggesting the role of the NO/AT2R axis in Ca 2+ control in podocytes. NO production correlates with podocyte volume increase, and scanning ion microscopy experiments further confirmed that AT2R activation and corresponding NO elevation are responsible for the protrusion of podocyte's lamellipodia. Finally, we found that in podocytes, NOS1 is responsible for NO bioavailability, accounting for 69±5% of the total NO response, while the remaining NO levels are generated by NOS2 (39±5%). Conclusion: Our data show that RAS activation promotes NO production in podocytes, mainly via the AT2R pathway. NO is crucial for Ca 2+ control in podocytes and lamellipodia formation, suggesting the essential role of NO in glomerular filtration barrier function.

Abstract 18: Persistent beneficial effects of angiotensinogen small interfering RNA (siRNA) and valsartan in spontaneously hypertensive rats after drug removal

Objective: Dual blockade of the renin-angiotensin system (RAS) with siRNA targeting hepatic angiotensinogen (AGT) plus the angiotensin receptor blocker valsartan synergistically lowers blood pressure and diminishes cardiac hypertrophy in spontaneously hypertensive rats (SHR). Since the effects of one siRNA injection may last for up to six months, here we evaluated whether the REVERSIR (reverse siRNA silencing, RVR) technology and/or stopping valsartan might acutely reverse the effects of dual RAS blockade in SHR. Methods: Ten-week old SHR were subjected to a 3-week treatment with vehicle or AGT-siRNA (10 mg/kg) + valsartan (4 mg/kg per day), followed by administration of vehicle or AGT-RVR at doses of 1, 10 and 20 mg/kg, both with and without continuation of valsartan, for 1 week. Mean arterial blood pressure (MAP) was monitored using radiotelemetry, and circulating AGT and renin were measured by enzyme-kinetic assay. Results: Baseline MAP was 143±2 mm Hg. Dual treatment lowered MAP by ≈70 mm Hg, cardiac hypertrophy (heart weight/tibia length) by ≈30%, and circulating AGT by >99%, while renin increased >100-fold versus vehicle. Discontinuing valsartan or applying AGT-RVR (1, 10 or 20 mg/kg) increased MAP similarly (by ≈20 mm Hg), while discontinuing valsartan + AGT-RVR (10 mg/kg) increased MAP by ≈40 mm Hg. Changes in cardiac hypertrophy mimicked those in MAP. Only valsartan discontinuation + AGT-RVR fully restored circulating AGT and renin to normal. When discontinuing valsartan only, AGT remained suppressed by >95%, and renin was up 10-fold, while with AGT-RVR 1, 10 and 20 mg/kg only, AGT suppression was 25, 50 and 50%, while renin was up 25-, 15- and 15-fold, respectively. Conclusions: Discontinuing valsartan or applying AGT-RVR in SHR treated with valsartan + AGT siRNA partially restored MAP, AGT, and renin, likely reflecting the fact that this approach replaces dual RAS blockade by single RAS blockade. However, although discontinuing valsartan plus AGT-RVR fully restored RAS activity, MAP and cardiac hypertrophy remained suppressed under this condition. This agrees with observations that early RAS inhibition resets genetic pathways and networks, allowing persistent blood pressure normalization even when treatment has stopped.

Abstract We140: Age-Dependent miR-34a and AGTRAP Cross-Modulation: a Novel Mechanism of Vascular Aging

Background: Renin-Angiotensin Aldosterone System (RAAS) activation plays a central role in vascular aging, leading to structural and functional alterations including vascular smooth muscle cell (VSMC) proliferation, migration and secretion of extracellular matrix and inflammatory molecules. The age-associated increase in Angiotensin II (Ang II) expression enhances AT1-receptor activity and determinates a pro-fibrotic and pro-inflammatory phenotype. Further, miR-34a expression is modulated by aging and increases in different tissues, including the mouse aorta, but no direct miR-34a target has been identified in the RAAS pathway that sustains age-dependent increase of pro-inflammatory signaling. Aims: The aim of our study is to evaluate the potential interaction between miR-34a and RAAS signaling in VSMCs. Methods and Results: miR-34a expression exhibited an age-dependent increase in Rhesus Monkey (8- to 26-year-old) and rat central arteries (8- and 30-month-old). In silico analysis indicated that AT1R-associated protein (AGTRAP), a negative modulator of AT1R signaling, is a potential miR-34a target suggesting that the age-dependent increase in miR-34a in the arterial vascular wall may decrease AGTRAP expression in arterial VSMC. Ang II enhanced miR-34a expression in 30-month-old rat and in human aorta SMCs (HASMCs), whereas AGTRAP and Sirtuin-1 (SIRT1) mRNA and protein level decreased. Immunohistochemistry analysis showed a decrease of AGTRAP in 18-month-old miR-34a knock-out mice compared to 2-month-old mice. By luciferase assay, we demonstrated that AGTRAP is a direct miR-34a target. Moreover, AGTRAP and SIRT1 decreased in HASMCs infected with miR-34a-encoding lentivirus and this effect was partially rescued in AGTRAP/miR-34a co-infected cells. Finally, pro-inflammatory genes IL-6, COX-2, MCP-1 and MFG-E8 expression was upregulated in Ang II-treated and miR-34a overexpressing HASMCs, and this effect was abolished in AGTRAP/miR-34a co-transfected cells. Conclusions: Our results show cross-modulation between miR-34a and AGTRAP. MiR-34a targeting AGTRAP increases the expression of pro-inflammatory molecules in VSMCs and represents a novel mechanism that modulates RAAS signaling in vascular aging. Statement: This research was supported in part by the Intramural Research Program of the NIH, National Institute on Aging.

Moroccan Antihypertensive Plants and their Mechanisms of Action.

The use of herbal remedies, medicinal plants, and their derivatives for the treatment and control of hypertension is well-known and widespread throughout Morocco. The aim of the study was to review the antihypertensive and vasorelaxant medicinal plants of the Moroccan pharmacopeia. To date, no review on Moroccan medicinal plants exhibiting antihypertensive effects has been performed, and their mechanism of action has not been specified. The objective of this review was to collect, analyze, and critically assess published publications on experimental and clinical research that explored the blood pressure-reducing abilities of Moroccan medicinal plant extracts. This study collected, processed, and critically analyzed published studies related to experimental and clinical research that investigated Moroccan herbal derivatives' blood pressure-lowering abilities using a number of scientific databases, including ScienceDirect, Scopus, PubMed, Google Scholar, and others. Plantlist.org was used to validate the right plant names. The results revealed 22 species of Moroccan medicinal plants belonging to 13 different groups with recognized antihypertensive properties. The species were abundant in a variety of chemical elements. Asteraceae (08 species), Lamiaceae (3 species), Apiaceae (2 species), and 1 species each from the following families: Parmeliaceae, Fabaceae, Cistaceae, Malvaceae, Polygonaceae, Brassicaceae, Myrtaceae, Rutaceae, Amaranthaceae, Rosaceae, and Lauraceae were the most frequently mentioned families for their antihypertensive properties. The most used parts were the leaves and the aerial parts. The two main methods of preparation among Moroccans were decoction and infusion. This study demonstrated the known antihypertensive and vasorelaxant properties of Moroccan medicinal plants in vivo and in vitro, as well as their mechanisms of action. Interestingly, phytochemicals can operate on blood vessels directly via a vasorelaxant impact involving a range of signaling cascades or indirectly by blocking or activating multiple systems, such as an angiotensin-converting enzyme (ACE), renin-angiotensin system (RAS), or diuretic activity. The review of the available data reveals that more work needs to be done to examine all the Moroccan medicinal plants that have been suggested as antihypertensive in published ethnopharmacological surveys. A review of the literature in this area reveals that methodologies of the experimental study need to be standardized, and purified molecules need to be studied. In addition, mechanistic investigations, when they exist, are generally incomplete. In contrast, only a few advanced clinical investigations have been conducted. However, all studies fail to determine the efficacy/safety ratio.

Inflammation, Oxidative Stress, and Endothelial Dysfunction in the Pathogenesis of Vascular Damage: Unraveling Novel Cardiovascular Risk Factors in Fabry Disease.

Anderson-Fabry disease (AFD), a genetic disorder caused by mutations in the α-galactosidase-A (GLA) gene, disrupts lysosomal function, leading to vascular complications. The accumulation of globotriaosylceramide (Gb3) in arterial walls triggers upregulation of adhesion molecules, decreases endothelial nitric oxide synthesis, and induces reactive oxygen species production. This cascade results in fibrotic thickening, endothelial dysfunction, hypercontractility, vasospasm, and a pro-thrombotic phenotype. AFD patients display increased intima-media thickness (IMT) and reduced flow-mediated dilation (FMD), indicating heightened cardiovascular risk. Nailfold capillaroscopy (NFC) shows promise in diagnosing and monitoring microcirculatory disorders in AFD, though it remains underexplored. Morphological evidence of AFD as a storage disorder can be demonstrated through electron microscopy and immunodetection of Gb3. Secondary pathophysiological disturbances at cellular, tissue, and organ levels contribute to the clinical manifestations, with prominent lysosomal inclusions observed in vascular, cardiac, renal, and neuronal cells. Chronic accumulation of Gb3 represents a state of ongoing toxicity, leading to increased cell turnover, particularly in vascular endothelial cells. AFD-related vascular pathology includes increased renin-angiotensin system activation, endothelial dysfunction, and smooth muscle cell proliferation, resulting in IMT increase. Furthermore, microvascular alterations, such as atypical capillaries observed through NFC, suggest early microvascular involvement. This review aims to unravel the complex interplay between inflammation, oxidative stress, and endothelial dysfunction in AFD, highlighting the potential connections between metabolic disturbances, oxidative stress, inflammation, and fibrosis in vascular and cardiac complications. By exploring novel cardiovascular risk factors and potential diagnostic tools, we can advance our understanding of these mechanisms, which extend beyond sphingolipid accumulation to include other significant contributors to disease pathogenesis. This comprehensive approach can pave the way for innovative therapeutic strategies and improved patient outcomes.

Cardiovascular Sequelae of Bronchopulmonary Dysplasia in Preterm Neonates Born before 32 Weeks of Gestational Age: Impact of Associated Pulmonary and Systemic Hypertension.

Bronchopulmonary dysplasia (BPD) remains the most common respiratory disorder of prematurity for infants born before 32 weeks of gestational age (GA). Early and prolonged exposure to chronic hypoxia and inflammation induces pulmonary hypertension (PH) with the characteristic features of a reduced number and increased muscularisation of the pulmonary arteries resulting in an increase in the pulmonary vascular resistance (PVR) and a fall in their compliance. BPD and BPD-associated pulmonary hypertension (BPD-PH) together with systemic hypertension (sHTN) are chronic cardiopulmonary disorders which result in an increased mortality and long-term problems for these infants. Previous studies have predominantly focused on the pulmonary circulation (right ventricle and its function) and developing management strategies accordingly for BPD-PH. However, recent work has drawn attention to the importance of the left-sided cardiac function and its impact on BPD in a subset of infants arising from a unique pathophysiology termed postcapillary PH. BPD infants may have a mechanistic link arising from chronic inflammation, cytokines, oxidative stress, catecholamines, and renin-angiotensin system activation along with systemic arterial stiffness, all of which contribute to the development of BPD-sHTN. The focus for the treatment of BPD-PH has been improvement of the right heart function through pulmonary vasodilators. BPD-sHTN and a subset of postcapillary PH may benefit from afterload reducing agents such as angiotensin converting enzyme inhibitors. Preterm infants with BPD-PH are at risk of later cardiac and respiratory morbidities as young adults. This paper reviews the current knowledge of the pathophysiology, diagnosis, and treatment of BPD-PH and BPD-sHTN. Current knowledge gaps and emerging new therapies will also be discussed.

Empagliflozin and dapagliflozin decreased atrial monoamine oxidase expression and alleviated oxidative stress in overweight non-diabetic cardiac patients.

The sodium-glucose-cotransporter 2 inhibitors (SGLT2i) are the blockbuster antidiabetic drugs that exert cardiovascular protection via pleiotropic effects. We have previously demonstrated that empagliflozin decreased monoamine oxidase (MAO) expression and oxidative stress in human mammary arteries. The present study performed in overweight, non-diabetic cardiac patients was aimed to assess whether the two widely prescribed SGLT2i decrease atrial MAO expression and alleviate oxidative stress elicited by exposure to angiotensin 2 (ANG2) and high glucose (GLUC). Right atrial appendages isolated during cardiac surgery were incubated ex vivo with either empagliflozin or dapagliflozin (1, 10µm, 12h) in the presence or absence of ANG2 (100nm) and GLUC (400mg/dL) and used for the evaluation of MAO-A and MAO-B expression and ROS production. Stimulation with ANG2 and GLUC increased atrial expression of both MAOs and oxidative stress; the effects were significantly decreased by the SGLT2i. Atrial oxidative stress positively correlated with the echocardiographic size of heart chambers and negatively with the left ventricular ejection fraction. In overweight patients, MAO contributes to cardiac oxidative stress in basal conditions and those that mimicked the renin-angiotensin system activation and hyperglycemia and can be targeted with empagliflozin and dapagliflozin, as novel off-target class effect of the SGLT2i.

Integrated analysis of gut microbiome and its metabolites in ACE2-knockout and ACE2-overexpressed mice.

Aberrant activation of the classic renin-angiotensin system (RAS) and intestinal micro dysbiosis adversely affect insulin resistance (IR), dyslipidemia, and other metabolic syndrome markers. However, the action of angiotensin-converting enzyme 2 (ACE2) and gut health in systemic homeostasis vary, and their interaction is not completely understood. We adopted a combinatory approach of metabolomics and fecal 16S rRNA analysis to investigate gut microbiota and metabolite in two different mouse models, ACE2 knockout (ACE2 KO) mice and the ACE2-overexpressing obese mice. 16S rRNA gene sequencing revealed that ACE2 influences microbial community composition and function, and ACE2 KO mice had increased Deferribacteres, Alcaligenaceae, Parasutterella, Catenibacterium, and Anaerotruncus, with decreased short-chain fatty acid (SCFA)-producing bacteria (Marvinbryantia and Alistipes). In contrast, ACE2-overexpressed mice exhibited increased anti-inflammatory probiotic (Oscillospiraceae, Marinifilaceae, and Bifidobacteriaceae) and SCFA-producing microbes (Rikenellaceae, Muribaculaceae, Ruminococcaceae, Odoribacter, and Alistipes) and decreased Firmicutes/Bacteroidetes, Lactobacillaceae, Erysipelotrichaceae, and Lachnospiraceae. Metabolome analysis indicated differential metabolites in ACE2 KO and ACE2-overexpression mice, especially the glucolipid metabolism-related compounds. Furthermore, correlation analysis between gut microbiota and metabolites showed a dynamic mutual influence affecting host health. Our study confirms for the first time a significant association between ACE2 status and gut microbiome and metabolome profiles, providing a novel mechanism for the positive effect of ACE2 on energy homeostasis.

Activation of angiotensin converting enzyme 2 promotes hippocampal neurogenesis via activation of Wnt/β-catenin signaling in hypertension

Hypertension-induced brain renin-angiotensin system (RAS) activation and neuroinflammation are hallmark neuropathological features of neurodegenerative diseases. Previous studies from our lab have shown that inhibition of ACE/Ang II/AT1R axis (by AT1R blockers or ACE inhibitors) reduced neuroinflammation and accompanied neurodegeneration via up-regulating adult hippocampal neurogenesis. Apart from this conventional axis, another axis of RAS also exists i.e., ACE2/Ang (1–7)/MasR axis, reported as an anti-hypertensive and anti-inflammatory. However, the role of this axis has not been explored in hypertension-induced glial activation and hippocampal neurogenesis in rat models of hypertension. Hence, in the present study, we examined the effect of ACE2 activator, Diminazene aceturate (DIZE) at 2 different doses of 10 mg/kg (non-antihypertensive) and 15 mg/kg (antihypertensive dose) in renovascular hypertensive rats to explore whether their effect on glial activation, neuroinflammation, and neurogenesis is either influenced by blood-pressure. The results of our study revealed that hypertension induced significant glial activation (astrocyte and microglial), neuroinflammation, and impaired hippocampal neurogenesis. However, ACE2 activation by DIZE, even at the low dose prevented these hypertension-induced changes in the brain. Mechanistically, ACE2 activation inhibited Ang II levels, TRAF6-NFκB mediated inflammatory signaling, NOX4-mediated ROS generation, and mitochondrial dysfunction by upregulating ACE2/Ang (1–7)/MasR signaling. Moreover, DIZE-induced activation of the ACE2/Ang (1–7)/MasR axis upregulated Wnt/β-catenin signaling, promoting hippocampal neurogenesis during the hypertensive state. Therefore, our study demonstrates that ACE2 activation can effectively prevent glial activation and enhance hippocampal neurogenesis in hypertensive conditions, regardless of its blood pressure-lowering effects.

Fluid Restriction for Patients with Heart Failure: Current Evidence and Future Perspectives.

Fluid restriction has long been believed to benefit patients with heart failure by counteracting the activated renin-angiotensin aldosterone system and sympathetic nervous activity. However, its effectiveness remains controversial. In this paper, we summarized the current recommendations and reviewed the scientific evidence on fluid restriction in the setting of both acute decompensated heart failure and compensated heart failure. While a recent meta-analysis demonstrated the beneficial effects of fluid restriction on both all-cause mortality and hospitalization compared to usual care, several weaknesses were identified in the assessment of the methodological quality of the meta-analysis using AMSTAR 2. Further randomized controlled trials with larger sample sizes are needed to elucidate the benefits of fluid restriction for both clinical outcomes and patient-reported outcomes in patients with heart failure.

The role of ACE2 in RAS axis on microglia activation in Parkinson’s disease

BackgroundThe classic renin-angiotensin system (RAS) induces organ damage, while the ACE2/Ang-(1–7)/MasR axis opposes it. However, the role of ACE2 in the brain is unclear. We studied ACE2′s role in the brain. MethodWe used male C57BL/6J (WT) mice, ACE2 knockout (KO) mice, and MPTP-induced mice. Behavioral tests confirmed successful modeling. We assessed the impact of ACE2 KO on the RAS axis and PD index, including ACE, ACE2, AT1, AT2, MasR, TH, α-syn, and Iba1. We investigated ACE2 and MasR’s involvement in microglial activation via western blot and immunofluorescence. GSE10867 and GSE26532 datasets were used to analyze the effects of AT1 antagonists and in vitro PD models on microglia. ResultBehavioral tests revealed that MPTP mice displayed motor deficits, depression, anxiety, and increased inflammatory markers in the SN and CPU, with reduced antioxidant capacity. ACE2 KO worsened these symptoms and exacerbated inflammation and oxidative stress. LPS-induced ACE2/MasR activation in BV2 cells demonstrated anti-inflammatory and neuroprotective effects by modulating microglial polarization. Antagonists inhibited microglial activation via inflammation and ROS processes. ConclusionThe RAS axis regulates inflammation and oxidative stress to maintain CNS function, suggesting potential targets for neurologic disease treatment. Understanding microglial RAS activation can offer new therapeutic strategies.

Prenatal LPS leads to increases in RAS expression within the PVN and overactivation of sympathetic outflow in offspring rats

The renin-angiotensin system (RAS) and the sympathetic nervous system (SNS) are two major blood pressure-regulating systems. The link between the renal and cerebral RAS axes was provided by reflex activation of renal afferents and efferent sympathetic nerves. There is a self-sustaining enhancement of the brain and the intrarenal RAS. In this study, prenatal exposure to lipopolysaccharide (LPS) led to increased RAS activity in the paraventricular nucleus (PVN) and overactivation of sympathetic outflow, accompanied by increased production of reactive oxygen species (ROS) and disturbances between inhibitory and excitatory neurons in PVN. The AT1 receptor blocker losartan and α2 adrenergic receptor agonist clonidine in the PVN significantly decreased renal sympathetic nerve activity (RSNA) and synchronously reduced systolic blood pressure. Prenatal LPS stimulation caused H3 acetylation at H3K9 and H3K14 in the PVN, which suggested that epigenetic changes are involved in transmitting the prenatal adverse stimulative information to the next generation. Additionally, melatonin treatment during pregnancy reduced RAS activity and ROS levels in the PVN; balanced the activity of inhibitory and excitatory neurons in the PVN; increased urine sodium secretion; reduced RSNA and blood pressure. In conclusion, prenatal LPS leads to increased RAS expression within the PVN and overactivation of the sympathetic outflow, thereby contributing to hypertension in offspring rats. Melatonin is expected to be a promising agent for preventing prenatal LPS exposure-induced hypertension.

YAP1-mediated dysregulation of ACE-ACE2 activity augments cardiac fibrosis upon induction of hyperglycemic stress

BackgroundDiabetic stress acts on the cardiac tissue to induce cardiac hypertrophy and fibrosis. Diabetes induced activated renin angiotensin system (RAS) has been reported to play a critical role in mediating cardiac hypertrophy and fibrosis. Angiotensin converting enzyme (ACE) in producing Angiotensin-II, promotes cardiomyocyte hypertrophy and fibrotic damage. ACE2, a recently discovered molecule structurally homologous to ACE, has been reported to be beneficial in reducing the effect of RAS driven pathologies. MethodsIn vivo diabetic mouse model was used and co-labelling immunostaining assay have been performed to analyse the fibrotic remodeling and involvement of associated target signaling molecules in mouse heart tissue. For in vitro analyses, qPCR and western blot experiments were performed in different groups for RNA and protein expression analyses. ResultsFibrosis markers were observed to be upregulated in the diabetic mouse heart tissue as well as in high glucose treated fibroblast and cardiomyocyte cells. Hyperglycemia induced overexpression of YAP1 leads to increased expression of β-catenin (CTNNB1) and ACE with downregulated ACE2 expression. The differential expression of ACE/ACE2 promotes TGFB1-SMAD2/3 pathway in the hyperglycemic cardiomyocyte and fibroblast resulting in increased cardiac fibrotic remodeling. ConclusionIn the following study, we have reported YAP1 modulates the RAS signaling pathway by inducing ACE and inhibiting ACE2 activity to augment cardiomyocyte hypertrophy and fibrosis in hyperglycemic condition. Furthermore, we have shown that hyperglycemia induced dysregulation of ACE-ACE2 activity by YAP1 promotes cardiac fibrosis through β-catenin/TGFB1 dependent pathway.

Renin angiotensin system-induced muscle wasting: putative mechanisms and implications for clinicians.

Renin angiotensin system (RAS) alters various mechanisms related to muscle wasting. The RAS system consists of classical and non-classical pathways, which mostly function differently. Classical RAS pathway, operates through angiotensin II (AngII) and angiotensin type 1 receptors, is associated with muscle wasting and sarcopenia. On the other hand, the non-classical RAS pathway, which operates through angiotensin 1-7 and Mas receptor, is protective against sarcopenia. The classical RAS pathway might induce muscle wasting by variety of mechanisms. AngII reduces body weight, via reduction in food intake, possibly by decreasing hypothalamic expression of orexin and neuropeptide Y, insulin like growth factor-1 (IGF-1) and mammalian target of rapamycin (mTOR), signaling, AngII increases skeletal muscle proteolysis by forkhead box transcription factors (FOXO), caspase activation and muscle RING-finger protein-1 transcription. Furthermore, AngII infusion in skeletal muscle reduces phospho-Bad (Ser136) expression and induces apoptosis through increased cytochrome c release and DNA fragmentation. Additionally, Renin angiotensin system activation through AT1R and AngII stimulates tumor necrosis factor-α, and interleukin-6 which induces muscle wasting, Last but not least classical RAS pathway, induce oxidative stress, disturb mitochondrial energy metabolism, and muscle satellite cells which all lead to muscle wasting and decrease muscle regeneration. On the contrary, the non-classical RAS pathway functions oppositely to mitigate these mechanisms and protects against muscle wasting. In this review, we summarize the mechanisms of RAS-induced muscle wasting and putative implications for clinical practice. We also emphasize the areas of uncertainties and suggest potential research areas.

#2605 Evaluation of cardiac fetal gene program in experimental uremia

Abstract Background and Aims Heart failure (HF) and uremia share several potent cardiac hypertrophic stimuli such as wall stress, sympathetic activation, renin angiotensin system activation and oxidative stress. In heart failure, induction of fetal gene program is one of the major processes through which such stimuli lead to progressive pathological hypertrophy and myocardial dysfunction. The fetal genes are activated by the transcription factor, myocyte enhance factor 2 (MEF2) which is a downstream target of the Ca++- Calmodulin Dependent Kinase II (CAMKII) pathway. The CAMKII pathway has been shown to be the major transduction pathway of the hypertrophic stimuli in HF [1, 2]. We hosphorzed that such mechanisms are also at play in uremic cardiomyopathy and tested the hypothesis in a rodent model of experimental uremia. Method Wistar rats (n = 18) had subtotal nephrectomy (STNx) or sham surgery (sham) and were followed up for 10 weeks. In vivo and in vitro cardiac assessments were performed. Cardiac tissue was extracted, and protein expression of CAMKII and hosphor-CAMKII were quantified using immunoblotting. Protein expression of MEF2 and its target fetal genes were also studied. Histological analyses were performed to quantify myocardial fibrosis. Data was analysed using an independent sample t-test with Welch's correction and expressed as mean± SEM. Results STNx resulted in higher echocardiographic left ventricular mass, heart weight to tibia length ratio and myocardial fibrosis in the STNx group (Fig. 1) demonstrating cardiac pathological hypertrophy. CaMKII signalling was activated and the expression of MEF2 was also increased following STNx (Fig. 1). There was trend towards increased expression of fetal genes (Fig. 1). However, the difference did not reach statistical significance. Conclusion The study shows that experimental uremia induces cardiac pathological hypertrophy along with activation of intracellular pathways involved in fetal gene induction. Further studies evaluating fetal genes at an earlier time course in the evolution of pathological hypertrophy will be worthwhile.

Statin administration or blocking PCSK9 alleviates airway hyperresponsiveness and lung fibrosis in high-fat diet-induced obese mice

BackgroundObesity is associated with airway hyperresponsiveness and lung fibrosis, which may reduce the effectiveness of standard asthma treatment in individuals suffering from both conditions. Statins and proprotein convertase subtilisin/kexin-9 inhibitors not only reduce serum cholesterol, free fatty acids but also diminish renin-angiotensin system activity and exhibit anti-inflammatory effects. These mechanisms may play a role in mitigating lung pathologies associated with obesity.MethodsMale C57BL/6 mice were induced to develop obesity through high-fat diet for 16 weeks. Conditional TGF-β1 transgenic mice were fed a normal diet. These mice were given either atorvastatin or proprotein convertase subtilisin/kexin-9 inhibitor (alirocumab), and the impact on airway hyperresponsiveness and lung pathologies was assessed.ResultsHigh-fat diet-induced obesity enhanced airway hyperresponsiveness, lung fibrosis, macrophages in bronchoalveolar lavage fluid, and pro-inflammatory mediators in the lung. These lipid-lowering agents attenuated airway hyperresponsiveness, macrophages in BALF, lung fibrosis, serum leptin, free fatty acids, TGF-β1, IL-1β, IL-6, and IL-17a in the lung. Furthermore, the increased RAS, NLRP3 inflammasome, and cholecystokinin in lung tissue of obese mice were reduced with statin or alirocumab. These agents also suppressed the pro-inflammatory immune responses and lung fibrosis in TGF-β1 over-expressed transgenic mice with normal diet.ConclusionsLipid-lowering treatment has the potential to alleviate obesity-induced airway hyperresponsiveness and lung fibrosis by inhibiting the NLRP3 inflammasome, RAS and cholecystokinin activity.Graphical abstract

Metabolic dysfunction-associated steatotic liver disease and atherosclerosis.

To update information about the relationship between metabolic dysfunction-associated steatotic liver disease (MASLD) and atherosclerosis. This review emphasizes the potential mechanisms linking MASLD with atherosclerosis and the possible causal relationships between these conditions. An increased risk of cardiovascular disease is related to MASLD. Several molecular, cellular, and metabolic mechanisms have been described to explain the development of atherothrombosis in MASLD patients. These include atherogenic dyslipidemia, low-grade vascular inflammation, endothelial dysfunction, foam cell formation, proliferation of vascular smooth muscle cells, insulin resistance, gut microbiota dysbiosis, activation of renin-angiotensin and sympathetic nervous systems, hypercoagulability, and decreased fibrinolysis. Also, there is recent evidence suggesting an association between genetically driven liver fat and coronary heart disease mediated by the causal effect of apoB-containing lipoproteins. Several meta-analyses and systematic reviews have reported a strong association between MASLD and cardiovascular outcomes. MASLD is an important and independent risk factor for atherosclerosis development. Multiple mechanisms may be involved in this association. Further research is required to establish a causal association between MASLD and atherosclerosis.