Search Results (148)

Hypertension is one major risk factor of cardiovascular diseases, and RAS plays vital role during the development of hypertension. To obtain a novel antihypertensive peptide, Coix glutelin was hydrolyzed by trypsin and further separated by Sephadex G10. Based on 751 identified sequences, pharmacophore mapping, molecular docking, and in silico proteolysis were applied to screen and optimize the candidate sequence. Finally, a novel peptide, ENWAAL, was generated with IC₅₀ of 210.57 μM, which acted with ACE in a competitively inhibitory pattern. The in vivo antihypertensive effect was evaluated in SHRs. Significant improvements were observed in hypertension-related characteristics, including blood pressure, cardiac structure and function, and serum angiotensin II (Ang II) level. In the brain, quantitative real-time PCR analysis revealed significant downregulation of angiotensin II type 1 receptor (AT1R) mRNA expression, concomitant with upregulation of angiotensin-converting enzyme 2 (ACE2) and MAS receptor. The protein expression of ACE and AT1R in the ENWAAL group also significantly decreased. This study can provide a candidate antihypertensive drug targeting RAS. Full article

Background/Objectives: Diuretic resistance is a recognized complication in patients with heart failure (HF) and is associated with worse clinical outcomes; however, information regarding its frequency and associated factors in hospitalized patients in Mexico is limited. This study aimed to describe the frequency of diuretic resistance in patients hospitalized with HF in a hospital unit in western Mexico and to identify factors associated with diuretic resistance. Methods: This retrospective study used data obtained from clinical records. Patients older than 18 years with decompensated HF whose complete clinical records included the variables of interest were included. Patients were classified according to the presence or absence of diuretic resistance. Bivariate and multivariate analyses were performed to evaluate factors associated with diuretic resistance. Results: A total of 76 patients were analyzed, and the frequency of diuretic resistance was 35.5% (n = 27). In bivariate analysis, type 2 diabetes mellitus, chronic kidney disease, elevated creatinine, urea, blood urea nitrogen (BUN), and urine protein levels, decreased glomerular filtration rate (GFR) and serum albumin, and prior treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) and angiotensin-converting enzyme inhibitors/angiotensin II receptor antagonists (ACEI/AARII) were significantly associated with diuretic resistance. In the multivariate logistic regression model, prior ACEI/AARII treatment, history of type 2 diabetes mellitus, BUN levels, and serum albumin levels remained independently associated with diuretic resistance classification. Conclusions: Diuretic resistance was frequent in this cohort of patients hospitalized with decompensated heart failure, and several clinical and biochemical factors were independently associated with its occurrence. These findings may help identify patients at higher risk of diuretic resistance, although they should be confirmed in future prospective studies. Full article

The angiotensin II type 1 (AT₁) receptor is a key component of the renin–angiotensin system (RAS) and a validated target for cardiovascular and renal disorders. Developing small molecules with defined AT₁ versus AT₂ binding profiles remains important for both therapeutic and mechanistic studies. Here, a series of novel imidazole-based compounds was synthesized and evaluated for their binding affinities toward angiotensin II type 1 (AT₁) and type 2 (AT₂) receptors. Binding studies were conducted by measuring the displacement of radiolabeled [³H]-angiotensin II ([³H]-AII) in PLC-PRF-5 human hepatoma cells for AT₁ receptors and calf cerebellum membranes for AT₂ receptors. Structure–activity relationship (SAR) analysis revealed that sulfonamide substitution significantly enhanced AT₁ receptor affinity, whereas sterically hindered derivatives and ester-containing compounds were less active. Molecular docking studies using the AT₁ receptor crystal structure (PDB: 8TH4) rationalized the observed activity trends. The most active compound showed high AT₁ affinity (Ki = 5 nM), comparable to losartan, and all compounds displayed preferential binding for AT₁ over AT₂ receptors. Full article

Background/Objectives: While the functions of angiotensin-converting enzyme (ACE) 1 and 2 are well established in peripheral tissues, the role of the spinal ACE1 and ACE2 pathways in the development of neuropathic pain remains unclear. This study examined the role of the spinal ACE1 and ACE2 pathways in trigeminal neuropathic pain produced by inferior alveolar nerve (IAN) injury. Methods: The experiments were conducted using male Sprague-Dawley rats (6–8 weeks old, weighing 220–250 g). The left mandibular second molar was extracted, and a dental mini-implant was placed to induce IAN injury. IAN injury produced robust and long-lasting mechanical allodynia and markedly increased angiotensinogen (AGT) expression within the ipsilateral trigeminal subnucleus caudalis (iTSC). Results: Neuropathic mechanical allodynia was inhibited by intracisternally administered losartan (an angiotensin II type-1 receptor antagonist), but not by an angiotensin II type-2 receptor antagonist. Intracisternal treatment with captopril (an ACE1 inhibitor) and diminazene aceturate (an ACE2 activator) produced significant anti-allodynic effects. Intracisternally injected angiotensin-(1-7) reduced neuropathic mechanical allodynia, and this anti-allodynic effect was blocked by pretreatment with A779, a Mas receptor inhibitor. In naïve rats, the intracisternal administration of DX600 (an ACE2 inhibitor) resulted in mechanical allodynia, which was inhibited by intracisternal pretreatment with losartan. IAN injury led to upregulated ACE1 expression and downregulated ACE2 expression in the iTSC. Conclusions: Our findings indicate that IAN injury induces a polarized shift in the ACEs within the iTSC, characterized by increased ACE1 and decreased ACE2 expression. Their modulation may therefore offer a promising strategy for developing effective treatments for chronic pain. Full article

Background: The correlation between renal volume (or mass) and nephron number in newborns allows the use of the total kidney volume (TKV) at birth as a surrogate for congenital nephron number. Previously, the wide variation in final nephron number (termed “nephron endowment”) has been attributed to polymorphisms of genes encoding proteins involved in glomerulogenesis, including key genetic variants in the renin–angiotensin system. However, there are no data concerning the role of polymorphism in the gene encoding type-2 angiotensin II receptor (AGTR2) in the modulation of nephron endowment in humans. Therefore, the aim of our study was to analyze the possible association between AGTR2:rs1403543 polymorphism and kidney volume in Polish full-term healthy newborns. Methods: The study group consisted of 208 healthy, Polish, full-term newborns born to healthy women with uncomplicated pregnancies. The AGTR2:rs1403543 polymorphism was identified by PCR-RFLP in genomic DNA extracted from cord blood leukocytes. Kidney volume was measured sonographically. Total kidney volume was calculated as the sum of left and right kidneys, and normalized for body mass (BM), body length (BL), or body surface area (BSA). Results: There were no significant differences in TKV/BM, TKV/BL, or TKV/BSA between male and female newborns, as well as in regard to the AGTR2:rs1403543 polymorphism. Conclusions: The results suggest a lack of association between the AGTR2:rs1403543 polymorphism and physiological variability in kidney volume in full-term newborns. Full article

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus disease 2019 (COVID-19), exploits angiotensin-converting enzyme 2 (ACE2) for cell entry, implicating the renin–angiotensin system (RAS) in disease pathogenesis. Hypertension (HT), a major comorbidity, is strongly influenced by genetic factors within RAS, including angiotensin ii receptor type 1 (AGTR1) and ACE2) polymorphisms. However, data on these variants in African populations remain scarce. This study investigated associations between AGTR1 and ACE2 single-nucleotide polymorphisms (SNPs), HT, and COVID-19 severity in patients at a Tshwane Academic Hospital. Methods: We genotyped AGTR1 and ACE2 SNPs in 94 PCR-confirmed COVID-19 patients using Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI-TOF) mass spectrometry. Clinical data were extracted from hospital records. Ordinal logistic regression models assessed relationships between SNPs, HT, and COVID-19 severity. Results: The cohort (mean age: 53.9 years; HT prevalence: 54.9%) exhibited mild (54.9%), moderate (18.6%), and severe (26.5%) COVID-19. Although the rs2106809 A genotype appeared to be associated with lower odds of severe disease (OR = 0.39, 95% CI: 0.14–1.08, p = 0.04), this observation should be interpreted with caution given the limited sample size of this study. Other SNPs and clinical variables showed no significant associations. Conclusions: This exploratory study represents the first description of AGTR1 and ACE2 SNP patterns in COVID-19 patients from Tshwane. While the rs2106809 variant may indicate a possible protective trend, the evidence remains preliminary. Age correlated with severity. Larger, multi-ethnic studies are needed to confirm these findings. Full article

Metabolic inflammation, a state of chronic low-grade inflammation linked to insulin resistance, plays a central role in the development of obesity-related conditions such as type 2 diabetes, non-alcoholic fatty liver disease (NAFLD), and cardiovascular disorders. In recent years, two molecules have gained significant prominence in this field, owing to their mechanistic involvement in metabolic inflammation and insulin resistance: fetuin-A (FetA), aliver-derived hepatokine, and chymase, a serine protease released from mast cells. Although they arise from distinct biological sources, they converge on overlapping inflammatory and metabolic pathways. FetA acts as an endogenous ligand for Toll-like receptor 4 (TLR4), activating nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, driving proinflammatory cytokine release, and impairing insulin signaling. Chymase, on the other hand, generates angiotensin II and activates transforming growth factor-β (TGF-β), thereby promoting oxidative stress, fibrosis, and secondary metabolic dysfunction. This review proposes a conceptual dual-target framework in which FetA and chymase are considered complementary, rather than independent, mediators of metabolic inflammation. Importantly, this framework is not intended to supersede other established pathways implicated in metabolic inflammation, but rather to provide an integrative perspective that complements existing hepatokine and immune-centered models. Their convergence on NF-κB and TGF-β signaling pathways highlights shared mechanistic nodes within metabolic inflammation. Accordingly, the emphasis of this review is on mechanistic integration within metabolic inflammation, rather than on immediate therapeutic innovation or clinical translation. Full article

The downregulation of Klotho in renal injury predicts the progression of chronic kidney disease (CKD). Klotho acts as an antagonist of the Wnt/β-catenin pathway, which is involved in the pathogenesis of proteinuria, glomerulosclerosis and tubulointerstitial fibrosis. We investigated whether losartan (L, angiotensin II type-1 receptor blocker) alone or combined with synthetic (tempol, T) or natural antioxidants (olive leaf extract, O) could alter Klotho/Wnt4/β-catenin signaling, thus reducing fibrosis and slowing the progression of focal segmental glomerulosclerosis (FSGS) in spontaneously hypertensive rats (SHR). The rats were divided into five groups. The control rats received a vehicle. The other groups received adriamycin (2 mg/kg, i.v., twice in a 3-week interval) for FSGS induction. Treatments with L, L+T and L+O (10, 10 + 100 and 10 + 80 mg/kg/day, respectively) were administered by gavage during six weeks. In the kidneys of model rats, Klotho and Wnt4 were downregulated, whereas β-catenin and fibronectin levels were increased compared with the control group. L+T did not alter Klotho, Wnt4 or fibronectin levels, while it further increased β-catenin. In contrast, L+O improved Klotho, and reduced β-catenin and fibronectin levels, although it increased PAI-1. The L+O combination reduced proteinuria more efficiently than L and decreased renal injury close to control levels. Although these findings indicate that combined treatment of losartan and olive leaf extract is promising in slowing the progression of the experimental FSGS, further clinical studies are needed to confirm its favorable outcomes and safety in CKD patients. Full article

Diabetes mellitus (DM) continues to be a global world health problem. Despite medical advances, both DM and chronic kidney disease (CKD) remain global health issues with high mortality and limited options to prevent end-stage renal failure. Current therapies encompass five classes of drugs: (1) angiotensin-converting-enzyme inhibitors (ACEI) or angiotensin II receptor blockers (AIIRB); (2) sodium-glucose-transporter 2 (SGLT2) inhibitors; (3) glucagon-like peptide-1 receptor agonists (GLP-1 RA); and (4) an antagonist of type 1 endothelin receptor (ET1R) with proven efficacy to reduce albuminuria and proteinuria. (5) The mineralocorticoid receptor antagonist (MRA) finerenone has been tested in RCTs as a kidney protective agent. In our review, we summarize many of the principal trials that have generated evidence in this regard. Many novel agents—many of them proven not only for DM management but also for the treatment of obesity with or without DM or heart failure (HF)—are now in development and may be added to the five classical pillars: other non-steroidal MRA (balcinrenone); aldosterone synthase inhibitors (baxdrostat and vicadrostat); other GLP-1 RA (tirzepatide, survodutide, retatrutide, and cagrilintide); ET1 R antagonists, (zibotentan); and soluble guanylate cyclase activators (avenciguat). These new agents aim to slow disease progression further and reduce cardiovascular risk. Future strategies rely on integrated, patient-centered approaches and personalized therapy to curb renal disease and its related complications. Full article

The deep fascia, traditionally regarded as a passive structural tissue, is now recognized as a metabolically and biologically active structure where biochemical signals and biomechanical forces interact to influence proprioception, pain, force transmission, and adaptation to mechanical load. In this study, the convergence point between Angiotensin II (Ang II) signaling via its receptor, Angiotensin type 1 receptor (AT1R), and the mechanosensor Yes-associated protein (YAP) was investigated in human fascial fibroblasts. The presence of angiotensin II (Ang II) receptors was confirmed in fibroblasts from the deep fascia, with the AT1 receptor being the most prevalent subtype. Short-term exposure to Ang II (15–30 min) caused YAP dephosphorylation and its translocation to the nucleus, indicating YAP activation. Notably, prolonged Ang II treatment (7 days) significantly increased the expression of fibrosis-related genes, including collagen types I and III (COL1A1, COL3A1), and hyaluronan binding protein 2 (HABP2). This gene expression was decreased by pretreatment with the AT1R antagonist irbesartan or the YAP inhibitor verteporfin. Additionally, Ang II promoted fibroblast proliferation/migration, key features of fibrotic progression, through AT1R-dependent pathways. These findings show that Ang II acts as both a biochemical and biomechanical signal in the deep fascia, activating YAP signaling and promoting fibrotic remodeling. Our results uncover a new Ang II–YAP pathway in fascial fibroblasts, offering potential targets for therapy in fibrosis and related conditions involving the deep fascia. Full article

We evaluated the effects of fenofibrate (FF) in a SU5416/hypoxia model of pulmonary arterial hypertension (PAH) with a specific focus on its influence on the renin–angiotensin system (RAS). We assessed right ventricular systolic pressure (RVSP), mean pulmonary artery pressure (mPAP), medial pulmonary artery wall thickening, right ventricular (RV) hypertrophy, systolic pulmonary artery pressure (SPAP), pulmonary artery effective elastance (PAEa), RV diastolic pressure (RVDP), RV developed pressure (RVDevP), right ventricular–pulmonary arterial coupling index (RVPAC), RV dp/dt max and dp/dt min. Levels of angiotensin II, angiotensin (1–7), angiotensin-converting enzyme 2 (ACE2), Bmpr2, Smad5 and nitrite (NO₂⁻) and nitrate (NO₃⁻) in the lung and RV were evaluated. The expression of AT1R, MAS receptors, and ACE2 in lung tissue was assessed. FF prevented the increase in RVSP, mPAP, RV hypertrophy, reduced pulmonary arterioles remodeling, and attenuated the rise in SPAP, mPAP, and PAEa. In the RV, it reduced RVDevP and prevented the decrease in dp/dt min, without affecting RVDP. RVPAC showed partial improvement. In lung tissue, FF decreased angiotensin II levels, the Ang II/Ang-(1–7) ratio, and reduced angiotensin II receptor type 1 (AT1R) expression, while preserving the receptor for the angiotensin-(1–7) (MAS) and ACE2. FF tended to restore Bmpr2/Smad5 expression. NO₂⁻ levels were preserved and tended to preserve (NO₃⁻) levels. In the RV, Ang-(1–7) increased, ACE2 was preserved, and NO₂⁻ and NO₃ levels were maintained. FF exerts protective effects in Su/Hx-induced PAH. Full article

The SARS-CoV-2 spike protein, through its receptor binding domain (S1-RBD), binds to the angiotensin-converting enzyme 2 (ACE2) receptor on the host cell membrane, leading to viral infection. Several mutations in S1-RBD in SARS-CoV-2 variants are known to enhance infection through an increased affinity for ACE2. While many reports are available describing the SARS-CoV-2 infection mechanism, there is a dearth of studies towards understanding the initial interaction of the S1-RBD with ACE2 on living host cells and the role of endocytosis and cytoskeleton in the process. Here, we reconstituted the interaction between S1-RBD- and ACE2-expressing host cells in a hybrid live cell-supported lipid bilayer (SLB) platform enabling live monitoring of the interaction between S1-RBD on SLBs and the ACE2 receptor on living cells and showed that cells depleted Omicron S1-RBD from SLB corrals, likely through endocytosis. Specifically, interaction of living host cells with S1-RBD-functionalized SLB substrates resulted in the enrichment of S1-RBD and ACE2 at the cell–SLB interface. Interaction of host cells with wild type (WT), Omicron, and Omicron Revertant S1-RBD functionalized on micron-scale SLB corrals, which mimic viral membranes but are flat, also resulted in their enrichment. However, cells interacting with Omicron S1-RBD revealed a depletion of the protein from many corrals, which was generally not observed with the WT S1-RBD and was reduced with the Omicron Revertant, which contains the Q493R mutation reversion, S1-RBD. Further, S1-RBD depletion coincided with the localization of the early endosomal marker EEA1. Importantly, treatment of cells with the clathrin inhibitor, pitstop 2, but not the myosin II inhibitor, blebbistatin, significantly reduced Omicron S1-RBD depletion. Collectively, these observations suggest that the SARS-CoV-2 Omicron variant has evolved, through mutations in its S1-RBD, to take advantage of the cellular endocytic pathway for enhanced infection, which is not observed with the parental SARS-CoV-2 and appears to be lost in the Omicron Revertant variant. Additionally, these results underscore the significance of the hybrid live cell–SLB platform in studying SARS-CoV-2 S1-RBD-ACE2 interaction and the potential impact of mutations in the S1-RBD on adapting to a specific cellular entry mechanism. 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) is a hormone system that controls blood pressure and fluid and electrolyte balance. Angiotensin II, a key effector, is produced from angiotensin I by angiotensin-converting enzyme (ACE) and exerts its effects through binding to its type 1 (AT1R) or type 2 (AT2R) receptors. AT1R activation promotes vasoconstriction, oxidative stress, endothelial dysfunction, peripheral vascular resistance, and atherosclerosis, all of which substantially contribute to cellular senescence and organismal ageing. Conversely, AT2R activation counteracts these effects by inducing vascular relaxation and attenuating vascular cell proliferation and migration, offering protection against occlusive vascular disease. Additionally, conversion of angiotensin II to angiotensin (1-7) or angiotensin I to angiotensin (1-9) by ACE2 provides further cardiovascular protection by lowering oxidative stress, inflammation, and abnormal cell growth. Bearing these in mind, measures to control angiotensin II synthesis or receptor activity have been at the forefront of antihypertensive treatment. This paper briefly reviews the RAAS and explores the dual role of angiotensin II in promoting disease and mediating vascular protection, with a focus on its impact on ageing and cardiovascular pathology. 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