Search Results (179)

Aminopeptidase A (APA) cleaves a single aspartate residue from the amino terminus of peptides within the renin angiotensin system (RAS). Since several RAS peptides contain an N-terminal aspartate, we developed an assay to evaluate the effect of recombinant APA on the cleavage of Ang I, Ang II, Ang-(1-7), Ang-(1-9), and Ang-(1-12). The latter peptide has been proposed to be a functional Ang II-forming substrate with a hypertensive action attributable to the formed Ang II acting on AT1 receptors. Here we investigated the following: (a) the hydrolytic action of APA on Ang-(1-12), Ang I (1-10), Ang-(1-9), Ang II and Ang-(1-7) and (b) whether Ang-(1-12) pressor activity is altered by recombinant APA (r-APA) or genetic APA deficiency. We found that (a) r-APA cleaves the N-terminal aspartate of not only Ang II but also [Ang-(1-12), Ang I (1-10), Ang-(1-9)] and [Ang-(1-7)]; (b) the pressor activity of Ang-(1-12) was abolished in the presence of Lisinopril or Telmisartan; (c) r-APA significantly attenuated the pressor activities of infused Ang I and Ang II but not Ang-(1-12); and (d) r-ACE2 also did not attenuate the pressor effect of infused Ang-(1-12). Thus, in addition to increasing blood pressure indirectly via the formation of Ang II, Ang-(1-12) increases blood pressure by an Ang II-independent mechanism. We conclude that APA has an antihypertensive effect attributable to rapid degradation of Ang II, and this action may have a therapeutic potential in forms of hypertension that are Ang II-dependent. In addition, APA metabolizes Ang-(1-12), a peptide that has a prohypertensive action, in part, as a source of Ang II formation but also by a yet to be determined action independent of Ang II. Full article

Arteriovenous malformations (AVMs) are congenital vascular anomalies defined by abnormal direct connections between arteries and veins due to their complex structure or endovascular approaches. Pharmacological strategies targeting the underlying molecular mechanisms are thus gaining increasing attention in an effort to determine the mechanism involved in AVM regulation. In this study, we examined 30 human tissue samples, comprising 10 vascular samples, 10 human fibroblasts derived from AVM tissue, and 10 vascular samples derived from healthy individuals. The pharmacological agents thalidomide, U0126, and rapamycin were applied to the isolated endothelial cells (ECs). The pharmacological treatments reduced the proliferation of AVM ECs and downregulated miR-135b-5p, a biomarker associated with AVMs. The expression levels of angiogenesis-related genes, including VEGF, ANG2, FSTL1, and MARCKS, decreased; in comparison, CSPG4, a gene related to capillary networks, was upregulated. Following analysis of these findings, skin samples from 10 AVM patients were reprogrammed into induced pluripotent stem cells (iPSCs) to generate AVM blood vessel organoids. Treatment of these AVM blood vessel organoids with thalidomide, U0126, and rapamycin resulted in a reduction in the expression of the EC markers CD31 and α-SMA. The establishment of AVM blood vessel organoids offers a physiologically relevant in vitro model for disease characterization and drug screening. The authors of future studies should aim to refine this model using advanced techniques, such as microfluidic systems, to more efficiently replicate AVMs’ pathology and support the development of personalized therapies. Full article

Patients with ulcerative colitis exhibit an increased risk for supraventricular arrhythmia during the active disease phase of the disease and show signs of atrial electrophysiological remodeling in remission. The goal of this study was to determine the basis for colitis-induced changes in atrial excitability. In a mouse model (C57BL/6; 3 months) of dextran sulfate sodium (DSS)-induced active colitis (3.5% weight/volume, 7 days), electrocardiograms (ECG) revealed altered atrial electrophysiological properties with a prolonged P-wave duration and PR interval. ECG changes coincided with a decreased atrial conduction velocity in Langendorff perfused hearts. Action potentials (AP) recorded from isolated atrial myocytes displayed an attenuated maximal upstroke velocity and amplitude during active colitis, as well as a prolonged AP duration (APD). Voltage clamp analysis revealed a colitis-induced shift in the voltage-dependent activation of the Na-current (I_Na) to more depolarizing voltages. In addition, protein levels of Na_v1.5 protein and connexin isoform Cx43 were reduced. APD prolongation depended on a reduction in the transient outward K-current (I_to) mostly generated by K_v4.2 channels. The changes in ECG, atrial conductance, and APD were reversible upon remission. The change in conduction velocity predominantly depended on the reversibility of the reduced Cx43 and Na_v1.5 expression. Treatment of mice with inhibitors of Angiotensin-converting enzyme (ACE) or Angiotensin II (AngII) receptor type 1 (AT1R) prevented the colitis-induced atrial electrophysiological remodeling. Our data support a colitis-induced increase in AngII signaling that promotes atrial electrophysiological remodeling and puts colitis patients at an increased risk for atrial arrhythmia. Full article

A growing body of evidence suggests the potent anti-inflammatory properties of the newly discovered arm of the renin–angiotensin–aldosterone system, ACE2/Ang-(1–7)/MasR, in various disease conditions. Our group was the first to report the anti-inflammatory properties of the Ang-(1–7) polypeptide in the murine dextran sulfate sodium (DSS) colitis model. Both its short half-life and high degradation rate limit the clinical use of Ang-(1–7). One way to compensate for these limitations is through the use of the non-peptide MasR agonist AVE0991. Herein, we aimed to study the anti-inflammatory effects of AVE0991 using the DSS model and the possible synergistic effects with other clinically available medications. Colitis severity was determined using both prophylactic and treatment approaches by gross anatomical and histological assessments and daily weight changes. The colonic expression level/activity of various pro-inflammatory and adhesion molecules was determined by western blotting, immunofluorescence, and proteomic profiling. We showed that AVE0991 treatment significantly reduced colitis severity more effectively with the prophylactic than the treatment approach. An additive anti-inflammatory effect was observed in the combination regimen with AVE0991 plus azathioprine, which was mediated through an increased colonic expression level of mucins and focal adhesion kinase, decreased colonic activity of p38 MAPK and Akt, and decreased colonic expression level of various pro-inflammatory mediators. In conclusion, these data suggest a promising potential for the non-peptide MasR agonist AVE0991 in the treatment of inflammatory bowel disease. Full article

Recent bioassay studies have unexpectedly supported the high (computationally predicted) binding affinities of angiotensin receptor blockers (ARBs) at α-adrenergic receptors (αARs) in isolated smooth muscle. Computational predictions from ligand docking studies are consistent with very low concentrations of ARBs (e.g., sartans or bisartans) that partially reduce (20–50%) the contractile response to phenylephrine, suggesting that some ARBs may function as partial inverse agonists at αARs. Virtual ligand screening (docking) and molecular dynamics (MD) simulations were carried out to explore the binding affinities and stabilities of selected non-peptide ligands (e.g., ARBs and small-molecule opioids) for several G-protein coupled receptor (GPCR) types, including angiotensin II (AngII) type 1 receptor (AT₁R), α1AR, α2AR, and μ-(µOR) and ժ-opioid receptors (ժOR). Results: All ligands docked preferentially to the binding pocket on the cell surface domain of the GPCR types investigated. Drug binding was characterized by weak interactions (hydrophobic, hydrogen bonding, pi-pi) and stronger ionic and salt-bridge interactions (cation-pi and cation-anion interactions). Ligands specific to each GPCR category showed considerable cross-binding with alternative GPCRs, with small-molecule medications appearing less selective than their peptide or ARB functional equivalents. ARBs that exhibit higher affinities for AT₁R also demonstrate higher affinities for µORs and ժORs than opiate ligands, such as fentanyl and naltrexone. Moreover, ARBs had a higher affinity for αARs than either alpha agonists (epinephrine and phenylephrine) or inhibitors (prazosin and doxazosin). MD simulations of membrane-embedded ARB-GPCR complexes proved stable over nanosecond time scales and suggested that some ARBs may behave as agonists or antagonists depending on the GPCR type. Based on the results presented in this and related investigations, we propose that agonists bind to the resting A-site of GPCRs, while inverse agonists occupy the desensitizing D-site, which partial agonists like morphine and fentanyl share, contributing to addiction. ARBs block both AngII and alpha receptors, suggesting that they are more potent antihypertensive drugs than ACE inhibitors. ARBs have the potential to inhibit morphine tolerance and appear to disrupt receptor desensitization processes, potentially by competing at the D-site. Our results suggest the possible therapeutic potential of ARBs in treating methamphetamine and opiate addictions. Full article

The tissue renin–angiotensin system (RAS) is a regulator of oxidative and inflammatory homeostasis by balancing its pro-oxidative/pro-inflammatory axis (angiotensin II, AngII, and AngII type-1 receptor, AT1) and its anti-oxidative/anti-inflammatory axis (AngII/AT2 and ACE2/Ang1-7/Mas receptors). An RAS dysregulation contributes to diseases, including Parkinson’s disease (PD). Immune mechanisms are involved in PD. An increase in levels of pro-oxidative/pro-inflammatory autoantibodies for AT1 (AT1-AAs) and ACE2 (ACE2-AAs) has been recently observed in PD. However, it is not known whether dysregulation of autoantibodies for AT2, MasR, and the correlations among different RAS-AAs occurs in PD. In 106 controls and 117 PD patients, we used enzyme-linked immunosorbent assays to determine correlations among serum RAS-AAs, and among RAS-AAs and pro-inflammatory cytokines and 27-hydroxycholesterol. PD patients showed an increase in MasR-AAs, and a more interconnected cluster of correlations among RAS-AAs (AT1-AA, AT2-AA, MasR-AA, ACE2-AA), changes in RAS-AA networks with sex and age, and differences in networks between RAS-AAs and major PD-related pro-inflammatory cytokines and 27-hydroxycholesterol. The association between AT1-AAs and PD remained significant even after adjustment for age and other variables. This study reveals a disease-specific network of RAS autoantibodies in PD that links immune and oxidative pathways and identifies new biomarker patterns and potential therapeutic targets. Full article

For the interaction of angiotensin II (AngII) with AngII type 1 receptors (AT₁R), two potential proton hopping pathways have been identified, each associated with distinct physiological outcomes. The octapeptide AngII (Asp¹-Arg²-Val³-Tyr⁴-Ile⁵-His⁶-Pro⁷-Phe⁸) appears to form a charge relay system (CRS) in solution in which the C-terminal carboxylate abstracts a proton from the His⁶ imidazole group, which, in turn, abstracts a proton from the Tyr⁴ hydroxyl (OH) group, creating a tyrosinate anion. When AngII binds to the AT₁R, the CRS can be reconstituted with D281 of the receptor taking up the role of the Phe⁸ carboxylate in the tripartite interaction, whilst the Phe⁸ carboxylate forms a salt bridge with K199 of the receptor. As a consequence, the Tyr⁴ OH of AngII is positioned with accessibility to either the Phe⁸ carboxylate (bound to K199) or the His⁶ imidazole (activated by D281), thereby creating a potential gating mechanism for AT₁R receptor signaling. This study summarizes evidence based on structure activity data for various analogs wherein Tyr⁴ OH interaction with His⁶ imidazole (CRS formation) leads to G protein sequestration and vasoconstriction, whereas Tyr⁴ OH interaction with Phe⁸ carboxylate (bound to K199) engenders arrestin-mediated vasodilation and receptor desensitization. These findings, combined with quantum mechanical (semiempirical) calculations of CRS proton transfer presented herein, provide insights for the therapeutic targeting of angiotensin receptor blockers (sartans) and the development of second-generation drugs (bisartans). Full article

The renin–angiotensin system (RAS) is the main endocrine and tissular component responsible for controlling cardiovascular homeostasis, which can be modulated by estrogen levels. This study investigated the effects of hormone treatments with estrogen and progestins on angiotensin-(1-7)-mediated [Ang-(1-7)] vasodilation in ovariectomized rats and the possible mechanisms involving the RAS. Female Wistar rats were divided into the following groups: sham (SHAM), ovariectomized (OVX), OVX and treated with 17β-estradiol (E2) (OE₂), OVX and treated with E2 and drospirenone (OE₂ + DRSP), and OVX and treated with medroxyprogesterone (MPA). Hormonal treatment was delivered via gavage for 28 days. Vascular responses to Ang-(1-7) were assessed in isolated aortic rings, and a Western blot of the thoracic aorta was used to determine the protein levels of angiotensin II (Ang II) type-1 receptor (AT₁R), Ang II type-2 receptor (AT₂R), Ang-(1-7) receptor (Mas), angiotensin-converting enzyme 2 (ACE2), and endothelial nitric oxide synthase (eNOS). The results showed impaired vascular reactivity caused by ovariectomy. Ang-(1-7) induced vasodilation in the OE₂, OE₂ + DRSP, and MPA-treated groups, while the administration of the AT₂R antagonist (PD123319) or the selective Mas antagonist (A779) increased the extent of vasorelaxation induced by Ang-(1-7) in the OVX + MPA group. There were no differences in the aortic levels of AT₁R or ACE2 between the groups, but the MPA group showed significantly increased levels of AT₂R and eNOS. We concluded that ovariectomy induced vascular dysfunction linked to RAS regulation, and both estrogen (E2) and progestins differentially restored these parameters. Full article

Aortic dissection (AD) is a life-threatening vascular condition with limited pharmacological options, and shared risk factors with cardiac disease include hypertension, atherosclerosis, smoking, and dyslipidemia. This study investigated Ferrostatin-1 (Fer-1), a ferroptosis inhibitor, in a BAPN/Ang-II-induced mouse model of AD, revealing significant therapeutic potential. Fer-1 significantly reduced AD incidence and mortality by preserving aortic wall integrity. RNA sequencing identified 922 differentially expressed genes, with 416 upregulated and 506 downregulated. Bioinformatics analysis revealed that Fer-1 modulates key regulators, such as MEF2C and KDM5A, impacting immune responses, oxidative stress, apoptosis, and lipid metabolism. Additionally, Fer-1 alters miRNA expression, with the upregulation of miR-361-5p and downregulation of miR-3151-5p, targeting pathways involved in inflammation, oxidative stress, and smooth muscle cell (SMC) phenotypic stability. Functional pathway analysis highlighted the inhibition of actin cytoskeleton, ILK, and IL-17 signaling, essential for SMC differentiation and extracellular matrix remodeling. Gene interaction network analysis identified 21 central molecules, including CXCR3, ACACA, and BPGM, associated with lipid metabolism, inflammation, and vascular remodeling. This research elucidates the mechanism of ferroptosis in AD pathogenesis and establishes Fer-1 as a promising therapeutic intervention. AD and cardiac diseases share molecular mechanisms, risk factors, and pathological processes, positioning AD within the broader scope of cardiovascular pathology. By attenuating lipid peroxidation, oxidative stress, and inflammation, Fer-1 may have cardioprotective effects beyond AD, providing a foundation for future translational research in cardiovascular medicine. Full article

Excessive activity of the hormone angiotensin II (AngII) is known to contribute to the pathogenesis of multiple cardiovascular diseases, including atherosclerosis, vascular remodeling, and hypertension, primarily through inducing gene expression changes. In this study, we identified LMCD1 (LIM and cysteine-rich domains 1, also known as Dyxin), primarily recognized as a transcription co-factor involved in various oncogenic processes, cardiac hypertrophy, and vascular remodeling, as a potential key factor in AngII-mediated effects in vascular smooth muscle cells (VSMCs). We demonstrated that AngII upregulates LMCD1 expression in primary rat VSMCs through type 1 angiotensin receptor (AT1-R) activation, leading to calcium signaling and p38 MAPK pathway activation. Additionally, we also demonstrated in A7r5 vascular smooth muscle cells that LMCD1 protein overexpression results in enhanced cell proliferation and cell migration. Our findings provide insights into the mechanisms by which AngII mediates changes in LMCD1 expression. The elevated expression of LMCD1 enhanced the cell proliferation and migration in VSMCs in vitro experiments, suggesting that LMCD1 may be an important factor in vascular remodeling and the pathogenesis of severe cardiovascular diseases. These results raise the possibility that LMCD1 could be a promising pharmacological target in the cardiovascular dysfunctions associated with AT1-R overactivation. Full article

Background/Objectives: Gastric cancer treatments can lead to significant alterations to patients’ gastrointestinal microbiome. However, differences in microbial impacts between gastrectomy and endoscopic submucosal dissection (ESD) remain underexplored. This study investigates how these treatments influence microbial diversity and composition in patients with stage I gastric cancer. Methods: Patients with pathologically confirmed stage I gastric cancer were recruited from Chung-Ang University Hospital between December 2016 and December 2019. This study analyzed fecal samples from 13 patients (ESD: n = 5; gastrectomy: n = 8) before and after treatment using 16S rRNA gene sequencing. Microbial diversity indices and taxonomic composition were compared, with follow-up extending up to two years. Results: In the total cohort, alpha diversity significantly decreased post-treatment (p < 0.05), and beta diversity analysis showed distinct clustering between pre- and post-treatment samples (p < 0.05). At the genus level, Bacteroides significantly decreased (p < 0.05), while Lactobacillus, Bifidobacterium, and Blautia showed significant increases (p < 0.05). Comparative analyses revealed that in the ESD group, alpha diversity remained unchanged, although beta diversity showed significant clustering (p < 0.05), without notable changes in major taxa. In contrast, surgical resection resulted in a significant reduction in alpha diversity (p < 0.05) and beta diversity clustering (p < 0.05), with increased abundances of Streptococcus and Blautia and decreased abundance of Bacteroides (p < 0.05). Conclusions: Surgical gastrectomy exerts significant effects on microbiome diversity and composition, while ESD has a more limited impact. These findings underscore the importance of considering microbiome changes in postoperative management. Full article

Background: Endocrine resistance in breast cancer is associated with the epithelial-to-mesenchymal transition (EMT), resulting in enhanced cell proliferation, motility, and invasion and leading to a poor prognosis. There are few studies regarding the role of Angiotensin II (Ang II) and Angiotensin 1–7 (Ang 1–7) in relation to breast cancer, with contradictory outcomes. This study aims to investigate the expression of Ang 1–7 and MAS-R and evaluate the effects of Ang II, Ang 1–7, and the MAS-R agonist AVE0991 on EMT induction and reversal. Methods: The effects of Ang II and Ang 1–7 on normal and breast cancer cell lines were determined using various techniques for cell proliferation (MTT), motility (scratch assay), and invasion (Cultrex assay). Also, the expression/localization profiles of Ang 1–7 and its receptor (MAS-R), as well as various EMT markers, were determined using immunofluorescence, western blot, and ELISA. Results: Ang II significantly decreased the motility of the tested cell lines; however, it did not have a significant effect on their proliferation or invasion. The expression profiles of the tested EMT markers were not affected by Ang II treatment. The expression levels of Ang 1–7 and MAS-R were significantly higher in the normal breast epithelial cells and estrogen receptor ER compared to the ER+ breast cancer cells. Treatment with Ang 1–7 or the non-peptide MAS-R agonist AVE0991 significantly reduced the migration and invasion of the tested cell lines without modulating the tested EMT markers. Compared to Ang 1–7, AVE0991 exhibited a more prominent dose-dependent inhibitory effect on the proliferation, motility, and invasion of the ER− breast cancer cells. Conclusions: Ang 1–7 and AVE0991 play a promising therapeutic role in breast cancer, in part by reducing cell motility and invasion. Full article

Nonarteritic anterior ischemic optic neuropathy (NAION) is an ischemic lesion of the anterior optic nerve (ON), currently untreatable due to the length of time from symptom onset until treatment. We evaluated angiotensin-(1-7) (Ang-(1-7)): the MAS1-receptor ligand, as a possible NAION treatment using the rodent NAION model (rNAION). Long-Evans rats were unilaterally rNAION-induced. One-day post-induction, lesion severity was quantified via optic nerve head (ONH) edema using spectral domain optical coherence tomography. Animals meeting rNAION induction criteria were randomized into (1) Subcutaneous Ang-(1-7) infusion for 28 days and (2) Vehicle. Visual function was assessed using both visual acuity and flash visual evoked potentials (fVEP). Tissues were collected >30d and RGC neurons were quantified by stereology. ONs were histologically examined for inflammation. Ang-(1-7) improved post-rNAION visual function. Ang-(1-7)-treated animals showed improved visual acuity (ANCOVA: p = 0.0084) and improved fVEP amplitudes (ANCOVA: p = 0.0378) vs vehicle controls. The relative degree of improvement correlated with ONH edema severity. Treated animals showed trends towards increased RGC survival, and reduced optic nerve inflammatory cell infiltration. Ang-(1-7) is the first agent effective ≥1 day after rNAION induction. Ang-(1-7) type agonists may be useful in improving long-term function and neuronal survival in clinical NAION and other forms of white matter ischemia. Full article

Background/Objective: Osteocytes are the most abundant cell type in the skeleton, with key endocrine functions, particularly in regulating osteoblast and osteoclast activity to maintain bone quality. Angiotensin II (Ang II), a critical component of the renin–angiotensin–aldosterone system, is well-known for its role in vasoconstriction during hypertension. Beyond its cardiovascular functions, Ang II participates in various biological processes, including bone metabolism. While its influence on osteoblast proliferation, differentiation, and osteoclastogenesis has been documented, its effects on osteocytes remain unexplored. This study hypothesized that Ang II enhances the osteoclastogenic activity of osteocytes. Methods: Mouse calvariae were cultured ex vivo in an Ang II-containing medium, analyzed via immunohistochemistry, and evaluated for osteoclastogenic gene expression through real-time PCR. Western blotting was employed to assess protein levels and signaling pathway activation in the MLO-Y4 osteocytic cell line in vitro. Results: Ang II significantly increased the expression of receptor activator of nuclear factor κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). These effects were abrogated by azilsartan, a blocker targeting Ang II type 1 receptors (AT1R). p38 and ERK1/2 in the MAPK pathway were also activated by Ang II. Conclusions: Ang II enhances osteocyte-mediated osteoclastogenesis via AT1R activation, highlighting its potential as a therapeutic target for bone diseases. Full article

Hypertension is associated with alterations in the composition and diversity of the intestinal microbiota. Indeed, supplementation with probiotics and prebiotics has shown promising results in modulating the gut microbiota and improving cardiovascular health. However, there are no studies regarding the possible beneficial effects of postbiotics on cardiovascular function and particularly on hypertension-induced cardiovascular alterations. Thus, the aim of this study was to analyze the effect of supplementation with the heat-treated Bifidobacterium animalis subsp. lactis CECT 8145 strain (BPL1™ HT), a postbiotic developed by the company ADM-Biopolis, on cardiovascular alterations induced by angiotensin II (AngII) infusion in mice. For this purpose, three groups of C57BL/6J male mice were used: (i) mice infused with saline (control); (ii) mice infused with AngII for 4 weeks (AngII); and (iii) mice supplemented with BPL1™ HT in the drinking water (1010 cells/animal/day) for 8 weeks and infused with AngII for the last 4 weeks (AngII + BPL1™ HT). AngII infusion was associated with heart hypertrophy, hypertension, endothelial dysfunction, and overexpression of proinflammatory cytokines in aortic tissue. BPL1™ HT supplementation reduced systolic blood pressure and attenuated AngII-induced endothelial dysfunction in aortic segments. Moreover, mice supplemented with BPL1™ HT showed a decreased gene expression of the proinflammatory cytokine interleukin 6 (Il-6) and the prooxidant enzymes NADPH oxidases 1 (Nox-1) and 4 (Nox-4), as well as an overexpression of AngII receptor 2 (At2r) and interleukin 10 (Il-10) in arterial tissue. In the heart, BPL1™ HT supplementation increased myocardial contractility and prevented ischemia–reperfusion-induced cardiomyocyte apoptosis. In conclusion, supplementation with the postbiotic BPL1™ HT prevents endothelial dysfunction, lowers blood pressure, and has cardioprotective effects in an experimental model of hypertension induced by AngII infusion in mice. Full article