Search Results (413)

Background and aims: The senescent phenotype transition of vascular smooth muscle cells (VSMCs) is a crucial risk factor for the occurrence and development of vascular diseases. Intermedin (IMD) has various protective effects on cardiovascular diseases. In this study, we aimed to explore the role and the related mechanism of IMD in the senescent phenotype transition of VSMCs of aorta in mice. Methods: The senescent phenotype transition of VSMCs was induced by angiotensin II (Ang II) administered by mini-osmotic pumps in Adm2^fl/fl and Adm2^fl/flTagCre mice. Mouse VSMCs from aorta were used in in vitro experiments. Results: The aortic mRNA level of IMD, namely Adm2, was significantly decreased in Ang II-treated mice. Senescence-associated β-galactosidase activity and protein expressions of p16 and p21 were increased in the aortas of Adm2^fl/flTagCre mice, which were further elevated in Ang II-treated Adm2^fl/flTagCre mice. In addition, Adm2 deficiency in VSMCs further increased the protein expressions of DNA damage markers including 53BP1 and γH2AX in aortas of Adm2^fl/flTagCre mice, and Ang II treatment increased their levels in aortas of Adm2^fl/flTagCre mice or in VSMCs. However, Ang II-induced increases in senescence-associated proteins and DNA damage markers could be mitigated by the administration of IMD in vitro. Mechanistically, IMD increased intracellular NAD⁺ by activating nicotinamide phosphoribosyl transferase (NAMPT), followed by enhancing poly (ADP-ribose) polymerase-1 (PARP1) activity. Inhibitors of PARP1 or NAMPT effectively blocked the beneficial role of IMD in the DNA damage of VSMCs. Conclusions: IMD alleviates DNA damage partially by activating NAMPT/PARP1, thereby inhibiting the senescent phenotype transition of VSMCs of aorta, which might shed new light on the prevention of vascular aging. Full article

The vascular 5-HT sympatho-modulation may involve inhibitory or potentiating pathways: nitric oxide (NO), endothelium-dependent hyperpolarization (EDH)-K⁺ channels, prostanoids, angiotensin II (Ang-II), or endothelin. Compared to males, female rats show differences in the serotonergic sympatho-regulation; therefore, we aimed to study the involvement of indirect pathways via 5-HT_1D-mediated inhibition and 5-HT_2A/3-mediated potentiation of vascular noradrenergic neurotransmission in females. An i.v. bolus of different inhibitors/blockers of modulators/mediators (NO, K⁺ channels, prostanoids, Ang-II, or endothelin) was administered prior to the infusion of the agonists, L-694,247 (5-HT_1D), TCB-2 (5-HT_2A), or 1-PBG (5-HT₃), in female pithed rats. In these conditions, the vascular sympathetic outflow was electrically stimulated to assess the vasopressor responses. The L-694,247 vascular sympatho-inhibition was abolished by a non-selective K⁺ channel blocker, tetraethylammonium. The 1-PBG sympatho-excitatory vascular effect was not modified by any of the inhibitors tested, whereas TCB-2 sympatho-potentiation was blocked solely by losartan (Ang-II type 1 receptor antagonist). Moreover, Ang-II levels were increased after TCB-2 infusion in females. The EDH pathway mediates the 5-HT_1D-induced sympatho-inhibition, while the 5-HT_2A-evoked sympatho-excitatory effect is associated with Ang-II. In contrast, the 5-HT₃ sympatho-potentiation does not involve any indirect pathway. These findings advance current understanding of the complex interactions between 5-HT and vascular homeostasis in female rats. Full article

Background: Abnormal activation of Angiotensin II (Ang II) serves as a primary trigger for myocardial hypertrophy and cardiac injury. Isoquercitrin (IQ) and Quercetin (Que) possess anti-inflammatory and anti-apoptotic properties, but their protective effects against Ang II-induced cardiac injury remain unclear. This study aimed to investigate the mechanisms and therapeutic efficacy of IQ and Que in heart failure. Methods: Cytotoxic effects of IQ and Que on Ang II-induced H9c2 rat cardiomyocyte apoptosis models were assessed in vitro using the CCK-8 assay. Reactive Oxygen Species (ROS) generation and apoptotic fluorescence levels were measured. WB analysis examined protein expression in inflammatory and apoptotic pathways. In vivo heart failure model was established in mice, with cardioprotective effects of IQ and Que evaluated via echocardiography. Molecular docking was employed to analyze ligand–target interactions. Results: IQ outperformed Que in promoting cell viability and decreasing ROS. IQ exhibited a more potent inhibitory effect on apoptosis through regulating Bax, Caspase-3, CytoC, and Bcl-2 and demonstrated superior suppression of cardiac inflammation by inhibiting phosphorylation of ERK, JNK, and P38. Compared with Que, IQ more effectively attenuated Ang II-induced cardiac injury by ameliorating reductions in EF% and FS%, suppressing ST-segment elevation, and significantly reducing serum levels of CK-MB, LDH, ANP, BNP, and FFA in a heart failure model. Molecular docking verified stronger binding affinity of IQ for key targets. Conclusions: IQ demonstrates superior cardioprotection over Que by regulating MAPK signaling and mitochondrial apoptosis pathways, supporting its potential as a therapeutic candidate for heart failure. Full article

Background: Abnormal mitochondrial energy metabolism is a key factor in the development and progression of cardiac hypertrophy. Hopeaphenol (HP), a tetramer of the natural polyphenol resveratrol, exhibits higher biological activity than resveratrol, but its specific role in cardiac hypertrophy and underlying mechanisms remains unclear. Methods: This study explored the protective effect and mechanism of hopeaphenol on cardiac hypertrophy through in vivo and in vitro experiments. In in vivo experiments, transverse aortic constriction (TAC) was used to induce cardiac hypertrophy in mice; HE, Masson, and WGA staining were applied to observe myocardial changes, ELISA was used to detect animal serum indicators, and the Cellular Thermal Shift Assay (CETSA) was conducted to verify the interaction between hopeaphenol and AMPK. In in vitro experiments, angiotensin II (Ang II) was used to induce hypertrophy of HL-1 cardiomyocytes, and the AMPK-specific inhibitor Compound C was employed to confirm the role of the AMPK pathway. Results: In in vivo experiments, TAC-induced cardiac hypertrophy in mice was characterized by left ventricular cavity enlargement and decreased ejection fraction; hopeaphenol treatment significantly improved these cardiac function indices, and HE, Masson, and WGA staining confirmed that hopeaphenol could restore cardiomyocyte morphology and reduce fibrosis. ELISA results of animal serum showed that hopeaphenol could improve metabolic disorders in TAC mice. Furthermore, CETSA confirmed a direct interaction between hopeaphenol and AMPK. In in vitro experiments, hopeaphenol reduced Ang II-induced hypertrophy and apoptosis of HL-1 cardiomyocytes, enhanced mitochondrial membrane potential, and decreased reactive oxygen species (ROS) levels by activating the AMPK pathway; moreover, the AMPK-specific inhibitor Compound C blocked these effects. This suggests that hopeaphenol’s cardioprotective effect is largely mediated by AMPK activation. Conclusions: The protective effect of hopeaphenol on cardiac hypertrophy is highly dependent on the activation of the AMPK signaling pathway, with CETSA and molecular docking supporting direct binding between hopeaphenol and AMPK; this pathway improves mitochondrial dysfunction through AMPK, thereby alleviating heart failure caused by pressure overload. This finding identifies hopeaphenol as a potential candidate for further development in the prevention and treatment of heart failure. Full article

Brassinin, a sulfur-containing phytoalexin, exerts anticancer and anti-inflammatory effects. Hydrogen sulfide (H₂S) is an important gasotransmitter with significant cardioprotective properties. The effects of brassinin on H₂S signaling and vascular smooth muscle cell (SMC) functions remain unexplored. This study found that brassinin protected against angiotensin II (Ang II)-induced SMC dysfunctions. These effects included the attenuation of excessive cell proliferation, migration, and oxidative stress; and upregulation of smooth muscle contractile protein expressions; and down-regulation of inflammatory gene expressions. Notably, brassinin did not directly release H₂S under the tested conditions; instead, it stimulated endogenous H₂S synthesis in cultured SMCs by inducing the expression of cystathionine gamma-lyase (CSE), a key H₂S-generating enzyme. Further mechanistic investigations revealed that brassinin may bind to the transcription factor C/EBPβ and enhance its interaction with the CSE promoter, thereby upregulating CSE transcription. In conclusion, our findings demonstrate that brassinin protects against SMC dysfunction, at least in part, by activating H₂S signaling rather than acting as a direct H₂S donor. These results provide new insights into the potential of brassinin as a therapeutic agent for improving vascular health and preventing cardiovascular diseases. Full article

In addition to its role in angiotensin II (Ang II) production, chymase exhibits various functions, including activation of latent transforming growth factor beta 1 (TGF-β1) and pro-matrix metalloproteinases (MMPs). However, the extent to which these Ang II-independent functions contribute to pathological conditions remains unclear. In this study, we investigated the Ang II-independent roles of chymase in cardiac remodeling and dysfunction. Eighteen male Syrian hamsters, aged 6 weeks and weighing 90–110 g, were used. Exogenous Ang II was administered to a hamster model that mirrors the human chymase-dependent Ang II production pathway, via subcutaneous osmotic mini pumps (2 mg/kg/day) for 4 weeks. A chymase-specific inhibitor, TY-51469 (10 mg/kg/day), was given daily starting 1 day after commencement of Ang II infusion. Evaluation showed that while systolic blood pressure increased significantly, only diastolic dysfunction developed over time. Ang II treatment led to elevated cardiac expression of chymase, TGF-β1, and MMP-2, and increased the number of chymase-positive mast cells, resulting in notable cardiac hypertrophy and fibrosis. TY-51469 effectively suppressed these molecular changes and improved both cardiac structure and diastolic dysfunction, despite continued Ang II exposure. These results suggest that chymase promotes cardiac remodeling and dysfunction not only through Ang II generation but also by activating profibrotic and matrix-degrading factors, such as TGF-β1 and MMP-2. Full article

The renin-angiotensin system (RAS) has evolved from being considered solely a peripheral endocrine system for cardiovascular control to being recognized as a complex molecular network with important functions in the central nervous system (CNS) and peripheral nervous system (PNS). Here we examine the organization, mechanisms of action, and clinical implications of cerebral RAS in physiological conditions and in various neurological pathologies. The cerebral RAS operates autonomously, synthesizing its main components locally due to restrictions imposed by the blood–brain barrier. The key elements of the system are (pro)renin; (pro)renin receptor (PRR); angiotensinogen; angiotensin-converting enzyme types 1 and 2 (ACE1 and ACE2); angiotensin I (AngI), angiotensin II (AngII), angiotensin III (AngIII), angiotensin IV (AngIV), angiotensin A (AngA), and angiotensin 1-7 (Ang(1-7)) peptides; RAS-regulating aminopeptidases; and AT1 (AT1R), AT2 (AT2R), AT4 (AT4R/IRAP), and Mas (MasR) receptors. More recently, alamandine and its MrgD receptor have been included. They are distributed in specific brain regions such as the hypothalamus, hippocampus, cerebral cortex, and brainstem. The system is organized into two opposing axes: the classical axis (renin/ACE1/AngII/AT1R) with vasoconstrictive, proinflammatory, and prooxidative effects, and the alternative axes AngII/AT2R, AngIV/AT4R/IRAP, ACE2/Ang(1-7)/MasR and alamandine/MrgD receptor, with vasodilatory, anti-inflammatory, and neuroprotective properties. This functional duality allows us to understand its role in neurological physiopathology. RAS dysregulation is implicated in multiple neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), and neuropsychiatric disorders such as depression and anxiety. In brain aging, an imbalance toward hyperactivation of the renin/ACE1/AngII/AT1R axis is observed, contributing to cognitive impairment and neuroinflammation. Epidemiological studies and clinical trials have shown that pharmacological modulation of the RAS using ACE inhibitors (ACEIs) and AT1R antagonists (ARA-II) not only controls blood pressure but also offers neuroprotective benefits, reducing the incidence of cognitive decline and dementia. These effects are attributed to direct mechanisms on the CNS, including reduction of oxidative stress, decreased neuroinflammation, and improved cerebral blood flow. Full article

The renin–angiotensin–aldosterone system (RAAS) plays a pivotal role in regulating cardiovascular function, fluid balance, and blood pressure. Recent research has revealed the RAAS’s influence extends beyond cardiovascular physiology, encompassing key roles in inflammation, fibrosis, immune regulation, cancer progression, and organ-specific disease mechanisms. This review provides a comprehensive overview of classical and alternative RAAS pathways, focusing on the dual roles of angiotensin II (Ang II) and angiotensin-(1–7) (Ang 1–7), mediated through AT1R, AT2R, MasR, and MrgD receptors. We discuss molecular signaling cascades, including mitochondrial, nuclear, and caveolae-mediated mechanisms, and explore the impact of RAAS modulation on hepatic fibrosis, vascular remodeling, and autoimmune inflammation. Genetic models and emerging pharmacologic strategies illustrate tissue-specific RAAS actions, emphasizing the therapeutic potential of enhancing the ACE2/Ang 1–7/Mas axis while inhibiting the deleterious ACE/Ang II/AT1R signaling. Furthermore, we highlight implications for veterinary medicine, particularly in canine chronic inflammatory enteropathies, where RAAS dysfunction may contribute to treatment resistance. Understanding RAAS complexity and inter-receptor crosstalk is essential for developing new therapeutic strategies targeting cardiovascular, hepatic, and inflammatory diseases in both human and veterinary contexts. Full article

G protein-coupled receptors (GPCRs) transmit through G proteins upon agonist activation, followed by phosphorylation by GPCR kinases (GRKs) to initiate β-arrestin signaling. However, the molecular mechanisms underlying GPCR signaling regulation by distinct agonists, GRK subtypes, and phosphorylation patterns remain poorly understood. The angiotensin II (AngII) type 1 receptor (AT1R), a prototypical GPCR, serves as an ideal model for studying biased ligands and signaling. Here, we investigated the wild-type (WT) AT1R and mutants of three potential phosphorylation motifs at its C-terminus (Motif I: S326/S328/S331, Motif II: T332/S335/T336/S338, and Motif III: S346/S347/S348/T349) using unbiased agonist AngII, β-arrestin-biased agonist TRV026, and G protein-biased agonist TRV056, along with GRK2/3/5/6 subtypes. We employed phosphorylation assays, β-arrestin pull-down experiments, molecular dynamics simulations, and AlphaFold3 predictions to dissect these mechanisms. Our results reveal that GRK2-mediated AT1R phosphorylation is abolished by mutations in Motifs I and II, with Motif II exhibiting a more pronounced effect. This phosphorylation was enhanced by Gβγ subunits. In contrast, GRK3-mediated phosphorylation remained unaffected by any mutations. GRK5 specifically phosphorylated Motif II, while GRK6 phosphorylated Motif II with the unbiased agonist AngII and both Motifs I and II with biased agonists TRV026 and TRV056. Notably, Motif II mutations reduced β-arrestin1/2 recruitment by GRK5/6 but not GRK2/3. Molecular dynamics simulations demonstrated that Motif II phosphorylation minimized steric hindrance, facilitating stable β-arrestin interactions, whereas Motif I phosphorylation increased intramolecular contacts that potentially impede recruitment. AlphaFold3 models provided detailed insights into the interactions between Motif II and β-arrestin1/2. Collectively, our findings elucidate diverse AT1R phosphorylation patterns driven by different agonists and GRK subtypes, offering a framework for developing signaling-biased AT1R therapeutics by decoding GRK-specific phosphorylation barcodes. Full article

The pivotal role of angiotensin II (AngII) in cardiovascular disease has been firmly established, as evidenced by a robust body of literature and the broad clinical application of AngII-inhibiting therapies. AngII type 1 receptor is the primary mediator of AngII action, and its activation initiates a multitude of cellular responses that contribute to the development of hypertension, structural changes in the heart and vasculature, and damage to target organs. This review examines AngII from a different perspective, exploring the link between the renin–angiotensin–aldosterone system and cardiovascular risk beyond hypertension, with particular emphasis on atherosclerosis development and progression. Full article

Background/Objectives: Nelumbo nucifera Gaertn. (lotus) seeds have traditionally been used to treat hypertension, though their mechanisms remain unclear. This study investigated the antihypertensive effects of lotus seed extract (LSE) and its mechanisms in rats with N^ω-nitro-L-arginine methyl ester (L-NAME)-induced hypertension. Methods: Male Sprague Dawley rats received L-NAME (40 mg/kg/day) in drinking water and were treated orally with LSE (5, 10, or 100 mg/kg/day), captopril (5 mg/kg/day), or a combination of LSE and captopril (2.5 mg/kg/day each) for 5 weeks. Hemodynamic parameters and histological changes in the left ventricle and aorta were assessed. Mechanistic studies included measurements of plasma nitric oxide (NO) metabolites, malondialdehyde (MDA), superoxide dismutase (SOD) activity, angiotensin II (Ang II), angiotensin-converting enzyme (ACE) activity, and protein expression via western blot. Results: L-NAME elevated systolic blood pressure and induced cardiovascular remodeling, oxidative stress, and renin-angiotensin system activation. LSE treatment reduced blood pressure, improved antioxidant status, increased NO bioavailability, and downregulated gp91^phox and AT₁R expression. The combination of low-dose LSE and captopril produced stronger effects than LSE alone, with efficacy comparable to captopril. Conclusions: These findings suggest that LSE exerts antihypertensive effects via antioxidant activity and inhibition of the renin-angiotensin system, supporting its potential as an adjunct therapy for hypertension. Full article

Hibiscus syriacus L. (HS), native to Eastern and Southern Asia, has been traditionally used in Asian herbal medicine for its anticancer, antimicrobial, and anti-inflammatory properties. Despite these recognized bioactivities, its potential cardioprotective effects, particularly in the setting of heart failure (HF), remain largely unexplored. This study aimed to investigate the effects of HS extracts and its bioactive constituents on angiotensin II (Ang II)-induced cardiac injury using an in vitro model with H9c2 rat cardiomyocytes. Cells exposed to Ang II were pretreated with HS extracts, and assays were performed to assess cell viability, reactive oxygen species (ROS) generation, protein synthesis, and secretion of inflammatory mediators, including tumor necrosis factor-alpha, interleukin 1β (IL-1β), and interleukin 6 (IL-6), as well as chemokine (CCL20) and HF-related biomarkers, such as brain natriuretic peptide (BNP) and endothelin-1. The results demonstrated that HS extracts significantly and dose-dependently attenuated Ang II-induced ROS accumulation and suppressed the secretion of pro-inflammatory cytokines, chemokines, BNP, and endothelin-1. Additionally, HS and its purified components inhibited Ang II-induced protein synthesis, indicating anti-hypertrophic effects. Collectively, these findings highlight the antioxidative, anti-inflammatory, and antihypertrophic properties of HS in the context of Ang II-induced cardiac injury, suggesting that HS may represent a promising adjunctive therapeutic candidate for HF management. Further in vivo studies and mechanistic investigations are warranted to validate its clinical potential. Full article

Background: Cerebral aneurysm (CA) is a focal or diffuse pathological dilation of the cerebral arterial wall that arises due to various etiological factors. It represents a serious vascular condition, particularly affecting the elderly, and carries a high risk of rupture and neurological morbidity. Clonidine (CL), an α2-adrenergic receptor agonist, has been reported to suppress aneurysm progression; however, its underlying molecular mechanisms, especially in relation to cerebral endothelial dysfunction, remain unclear. This study aimed to investigate the potential of CL to mitigate CA development by modulating apoptosis, inflammation, and oxidative stress in an Angiotensin II (Ang II)-induced endothelial injury model. Methods: Human brain microvascular endothelial cells (HBMECs) were used to establish an in vitro model of endothelial dysfunction by treating cells with 1 µM Ang II for 48 h. CL was administered 2 h prior to Ang II exposure at concentrations of 0.1, 1, and 10 µM. Cell viability was assessed using the MTT assay. Oxidative stress markers, including reactive oxygen species (ROS) and Nitric Oxide (NO), were measured using 2′,7′–dichlorofluorescin diacetate (DCFDA). Gene expression levels of vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMP-2 and MMP-9), high mobility group box 1 (HMGB1), and nuclear factor kappa B (NF-κB) were quantified using RT-qPCR. Levels of proinflammatory cytokines; tumor necrosis factor-alpha (TNF-α), Interleukin-6 (IL-6), and interferon-gamma (IFN-γ); were measured using commercial ELISA kits. Results: Ang II significantly increased ROS production and reduced NO levels, accompanied by heightened proinflammatory cytokine release and endothelial dysfunction. MTT assay revealed a marked decrease in cell viability following Ang II treatment (34.18%), whereas CL preserved cell viability in a concentration-dependent manner: 44.24% at 0.1 µM, 66.56% at 1 µM, and 81.74% at 10 µM. CL treatment also significantly attenuated ROS generation and inflammatory cytokine levels (p < 0.05). Furthermore, the expression of VEGF, HMGB1, NF-κB, MMP-2, and MMP-9 was significantly downregulated in response to CL. Conclusions: CL exerts a protective effect on endothelial cells by reducing oxidative stress and suppressing proinflammatory signaling pathways in Ang II-induced injury. These results support the potential of CL to mitigate endothelial injury in vitro, though further in vivo studies are required to confirm its translational relevance. Full article

Background/Objectives: Perioperative hypotension during kidney transplantation poses a risk to graft function and survival. Angiotensin II (AngII) is an endogenous vasoconstrictor targeting the renin–angiotensin–aldosterone system (RAAS) to increase blood pressure. Black patients may have a different response to synthetic angiotensin II (AT2S) compared to non-Black patients, given differential expressions in renin profiles. The purpose of this study is to assess the difference between Black and non-Black patients in total vasopressor duration and usage when AT2S is first line for hypotension during kidney transplantation. Methods: A single-center, retrospective cohort study comparing Black and non-Black patients who required AT2S as a first-line vasopressor for hypotension during the perioperative period of kidney transplantation. Results: The primary outcome evaluating total usage of vasopressors found that Black patients required longer durations of vasopressors (36.9 ± 66.8 h vs. 23.7 ± 31.7 h; p = 0.022) but no difference in vasopressor amount (0.07 ± 0.1 NEE vs. 0.05 ± 0.1 NEE; p = 0.128) compared to non-Black patients. Regression analysis found that body weight was associated with the duration of vasopressors (p < 0.05), while baseline systolic blood pressure was inversely associated with it. Longer duration of vasopressors and duration of transplant surgery were associated with delayed graft function in regression analysis (p < 0.05). Conclusions: Black patients had a longer duration of vasopressors, but this was not driven by differences in usage of AT2S. As baseline weight was significantly higher in Black patients and associated with duration of usage, perhaps the metabolic differences in our Black patients led to the observed differences. Regardless, longer durations of vasopressors were associated with delayed graft function, making this an area of utmost importance for continued investigation. Full article

The renin–angiotensin–aldosterone system (RAAS) plays a central role in cardiovascular and renal homeostasis and is increasingly recognized for its broad immunomodulatory effects. Pharmacological RAAS inhibition, primarily via angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), has demonstrated therapeutic value beyond its use in hypertension and heart failure, extending to autoimmune, infectious, oncologic, and neurodegenerative conditions. ACEIs and ARBs modulate both innate and adaptive immune responses through Ang II-dependent and -independent mechanisms, influencing macrophage polarization, T-cell differentiation, cytokine expression, and antigen presentation. Notably, ACEIs exhibit Ang II-independent effects by enhancing antigen processing and regulating amyloid-β metabolism, offering potential neuroprotective benefits in Alzheimer’s disease. ARBs, particularly telmisartan and candesartan, provide additional anti-inflammatory effects via PPARγ activation. In cancer, RAAS inhibition affects tumor growth, angiogenesis, and immune surveillance, with ACEIs and ARBs showing distinct yet complementary impacts on tumor microenvironment modulation and chemotherapy cardioprotection. Moreover, ACEIs have shown promise in autoimmune myocarditis, colitis, and diabetic nephropathy by attenuating inflammatory cytokines. While clinical evidence supports the use of centrally acting ACEIs to treat early cognitive decline, further investigation is warranted to determine the long-term outcomes across disease contexts. These findings highlight the evolving role of RAAS inhibitors as immunomodulatory agents with promising implications across multiple systemic pathologies. Full article