Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology

Alterations of the gut microbiota in patients with diabetic nephropathy and its association with the renin-angiotensin system

Objective

Type 2 Diabetes Mellitus (T2DM) is a global health concern, with complications such as diabetic nephropathy (DN) affecting 16.6% of patients and contributing to end-stage renal failure. Emerging research suggests that gut microbial communities may influence DN progression, potentially through mechanisms involving the renin-angiotensin system (RAS). This study aimed to evaluate changes in specific microbial genera in individuals with T2DM, both with and without DN, and to explore their associations with renal function markers and RAS activation.

Methods

A total of 120 participants were categorized into three groups: healthy controls, T2DM without DN, and T2DM with DN. Microbial abundances of genera including Escherichia, Prevotella, Bifidobacterium, Lactobacillus, Roseburia, Bacteroides, Faecalibacterium, and Akkermansia were quantified using qPCR targeting the bacterial 16 S rRNA gene. Gene expression levels of RAS-associated markers (ACE, AGT1R, AT2R, and Ang II) and inflammation-related genes (TNF-α, TLR4) were analyzed in peripheral blood mononuclear cells via qPCR.

Results

The study identified significant alterations in microbial composition. Genera such as Faecalibacterium, Akkermansia, Roseburia (butyrate producers), and Bifidobacterium (a potential probiotic) were markedly reduced in T2DM and DN groups compared to controls. Increased mRNA expression of RAS-related genes, including ACE, AGT1R, and Ang II, was observed in these groups. We also foun correlations between altered microbial genera, RAS gene expression, and clinical markers of renal dysfunction.

Conclusion

The findings suggest that specific microbial genera may influence the pathogenesis of DN through RAS activation and inflammatory pathways. These insights highlight potential therapeutic targets for mitigating DN progression in T2DM patients.

Transport and action of sesame protein-derived ACE inhibitory peptides ITAPHW and IRPNGL

Vascular endothelial dysfunction is an important pathogenic factor in hypertension, in which angiotensin-converting enzyme (ACE) plays an important role. Peptides that bind to ACE may attenuate vascular endothelial dysfunction by altering the structure of ACE. This study demonstrated that ITAPHW and IRPNGL were resistant to simulated gastrointestinal fluid and were transported across the Caco-2 monolayer via the intercellular space, with ITAPHW showing a high apparent permeability coefficient of (1.44 ± 0.01) × 10-5 cm/s. Subsequently, multispectral analysis and molecular dynamic simulation revealed the stability, conformation changes, and potential binding sites of ITAPHW- and IRPNGL-ACE complex. Furthermore, ITAPHW and IRPNGL alleviated endothelial dysfunction in the angiotensin I-induced human umbilical vein endothelial cells (HUVECs) by reducing ACE activity and the concentrations of angiotensin II and endothelin-1 (ET-1), while promoting the level of nitric oxide (NO), endothelial nitric oxide synthase (eNOS), cyclic guanosine 3', 5'-monophosphate (cGMP), and ACE2.

Clinical studies in Myxomatous Mitral Valve Disease dogs: most prescribed ACEI inhibits ACE2 enzyme activity and ARB increases AngII pool in plasma

The hypertension patient population has doubled since 1990, affecting 1.3 billion globally and >75% live in low-and middle-income countries. Angiotensin Converting Enzyme Inhibitors (ACEI) and Angiotensin Receptor Blockers (ARB) are the most prescribed drugs (>160 million times in the US), but mortality increased >30% since 1990s globally. Clinical relevance of Myxomatous Mitral Valve Disease (MMVD) is directly linked to WHO group 2 pulmonary hypertension, with no disease specific therapies. Therefore, MMVD pet dogs with elevated systolic blood pressure treated with ACEI/ARB, were supplemented with oral ACE2 enzyme and Angiotensin1-7 (Ang1-7) bioencapsulated in plant cells. The oral ACE2/Ang1-7 was well tolerated by healthy and MMVD dogs with no adverse events and increased sACE2 activity by 670-755% with ARB (Telmisartan) than with ACEI (Enalapril) background therapy. In vitro rhACE2 activity was inhibited >90% by ACEIs enalapril/benazeprilat at higher doses but lisinopril inhibited at much lower doses. Membrane ACE2 activity evaluated in exosomes was 43-fold higher than the sACE2 and this was also inhibited 211% by ACEI, when compared to ARB. Background ACEI treatment reduced the Ang-II pool by 11-20-fold and proportionately decreased the abundance of Ang1-7 + Ang1-5 peptides. In contrast, ARB treatment increased Ang-II pool 11-20-fold and Ang1-7 + Ang1-5 by 160-260%. Systolic blood pressure was regulated by ARB better than ACEI, despite very high Ang-II levels. This first report on evaluation of metabolic pools in the RAS pathway identifies surprising interactions between ACEI/ARB/ACE2 and significant changes in key molecular dynamics. Affordable biologics developed in plant cells may offer potential new treatment options for hypertension.

Systemic aging fuels heart failure: Molecular mechanisms and therapeutic avenues

Systemic aging influences various physiological processes and contributes to structural and functional decline in cardiac tissue. These alterations include an increased incidence of left ventricular hypertrophy, a decline in left ventricular diastolic function, left atrial dilation, atrial fibrillation, myocardial fibrosis and cardiac amyloidosis, elevating susceptibility to chronic heart failure (HF) in the elderly. Age-related cardiac dysfunction stems from prolonged exposure to genomic, epigenetic, oxidative, autophagic, inflammatory and regenerative stresses, along with the accumulation of senescent cells. Concurrently, age-related structural and functional changes in the vascular system, attributed to endothelial dysfunction, arterial stiffness, impaired angiogenesis, oxidative stress and inflammation, impose additional strain on the heart. Dysregulated mechanosignalling and impaired nitric oxide signalling play critical roles in the age-related vascular dysfunction associated with HF. Metabolic aging drives intricate shifts in glucose and lipid metabolism, leading to insulin resistance, mitochondrial dysfunction and lipid accumulation within cardiomyocytes. These alterations contribute to cardiac hypertrophy, fibrosis and impaired contractility, ultimately propelling HF. Systemic low-grade chronic inflammation, in conjunction with the senescence-associated secretory phenotype, aggravates cardiac dysfunction with age by promoting immune cell infiltration into the myocardium, fostering HF. This is further exacerbated by age-related comorbidities like coronary artery disease (CAD), atherosclerosis, hypertension, obesity, diabetes and chronic kidney disease (CKD). CAD and atherosclerosis induce myocardial ischaemia and adverse remodelling, while hypertension contributes to cardiac hypertrophy and fibrosis. Obesity-associated insulin resistance, inflammation and dyslipidaemia create a profibrotic cardiac environment, whereas diabetes-related metabolic disturbances further impair cardiac function. CKD-related fluid overload, electrolyte imbalances and uraemic toxins exacerbate HF through systemic inflammation and neurohormonal renin-angiotensin-aldosterone system (RAAS) activation. Recognizing aging as a modifiable process has opened avenues to target systemic aging in HF through both lifestyle interventions and therapeutics. Exercise, known for its antioxidant effects, can partly reverse pathological cardiac remodelling in the elderly by countering processes linked to age-related chronic HF, such as mitochondrial dysfunction, inflammation, senescence and declining cardiomyocyte regeneration. Dietary interventions such as plant-based and ketogenic diets, caloric restriction and macronutrient supplementation are instrumental in maintaining energy balance, reducing adiposity and addressing micronutrient and macronutrient imbalances associated with age-related HF. Therapeutic advancements targeting systemic aging in HF are underway. Key approaches include senomorphics and senolytics to limit senescence, antioxidants targeting mitochondrial stress, anti-inflammatory drugs like interleukin (IL)-1β inhibitors, metabolic rejuvenators such as nicotinamide riboside, resveratrol and sirtuin (SIRT) activators and autophagy enhancers like metformin and sodium-glucose cotransporter 2 (SGLT2) inhibitors, all of which offer potential for preserving cardiac function and alleviating the age-related HF burden.

Endothelial FOSL1 drives angiotensin II-induced myocardial injury via AT1R-upregulated MYH9

Vascular remodeling represents a pathological basis for myocardial pathologies, including myocardial hypertrophy and myocardial infarction, which can ultimately lead to heart failure. The molecular mechanism of angiotensin II (Ang II)-induced vascular remodeling following myocardial infarction reperfusion is complex and not yet fully understood. In this study, we examined the effect of Ang II infusion on cardiac vascular remodeling in mice. Single-cell sequencing showed Ang II induced cytoskeletal pathway enrichment and that FOS like-1 (FOSL1) affected mouse cardiac endothelial dysfunction by pseudotime analysis. Myosin heavy chain 9 (MYH9) was predominantly expressed in primary cardiac endothelial cells. The Ang II type I receptor blocker telmisartan and the protein kinase C inhibitor staurosporine suppressed Ang II-induced upregulation of MYH9 and FOSL1 phosphorylation in human umbilical vein endothelial cells. Silencing MYH9 abolished Ang II-mediated inhibition of angiogenesis in human umbilical vein endothelial cells, and attenuated AngII-induced vascular hyperpermeability. We found that FOSL1 directly bound to the MYH9 promoter and thus activated transcription of MYH9 by the dual luciferase reporter and chromatin immunoprecipitation assays, leading to vascular dysfunction. In vivo, 6 weeks after injecting adeno-associated virus-ENT carrying the TEK tyrosine kinase (tie) promoter-driven short hairpin RNA for silencing FOSL1 (AAV-tie-shFOSL1), cardiac function represented by the ejection fraction and fractional shortening was improved, myocardial fibrosis was decreased, protein levels of phosphorylated FOSL1, MYH9, and collagen type I alpha were reduced, and cardiac vascular density was recovered in mice with endothelial Fosl1-specific knockdown in Ang II-infused mice. In ischemia-reperfusion mice, AAV-shFosl1 mice had a reduced infarct size and preserved cardiac function compared with control AAV mice. Our findings suggest a critical role of the FOSL1/MYH9 axis in hindering Ang II-induced vascular remodeling, and we identified FOSL1 as a potential therapeutic target in endothelial cell injuries induced by myocardial ischemia-reperfusion.

Inhibition of AGTR1 attenuates cell proliferation after glaucoma filtration surgery via NF-κB pathway-mediated G0/G1-phase cell cycle arrest

Fibroblast proliferation after glaucoma filtration surgery (GFS) plays a pivotal role in scar formation. Angiotensin type 1 receptor (AGTR1) is involved in tissue remodeling. Our previous study demonstrated that treatment with an AGTR1 blocker prolonged the survival of filtering blebs following GFS. However, whether AGTR1 participates in fibroblast proliferation after GFS remains unclear. This study examined the mechanisms underlying the involvement of AGTR1 in the activation of cell proliferation following GFS. AGTR1 expression was increased in Tenon capsule tissue of patients with glaucoma. AGTR1 inhibition resulted in a decrease in TGF-β2-induced human Tenon capsule fibroblast (HTF) proliferation and a mitigation of subconjunctival cell proliferation following GFS. Additionally, lower AGTR1 expression led to a higher percentage of HTFs in the G0/G1 phase via the p21Waf1/Cip1/Cyclin D/Cyclin E pathway. Furthermore, the addition of BAY 11-7082, a blocker of the NF-κB pathway, resulted in further inhibition of Ki67, Cyclin D, and Cyclin E expressions and an increase in the percentage of HTFs in the G0/G1 phase. In conclusion, our findings indicate that AGTR1 inhibition can attenuate HTF proliferation by leading to cell cycle arrest in the G0/G1 phase through the NF-κB pathway. Targeting AGTR1 is a feasible strategy for mitigating cell proliferation following GFS.

Inhibition of Renin Release, a Crucial Event in Homeostasis, is Mediated by Coordinated Calcium Oscillations within Juxtaglomerular Cell Clusters

BACKGROUND

Juxtaglomerular (JG) cells are sensors that control blood pressure (BP) and fluid-electrolyte homeostasis. They are arranged as clusters at the tip of each afferent arteriole. In response to a decrease in BP or extracellular fluid volume, JG cells secrete renin, initiating an enzymatic cascade that culminates in the production of angiotensin II (AngII), a potent vasoconstrictor that restores BP and fluid-electrolyte homeostasis. In turn, AngII exerts negative feedback on renin release concomitantly with increased intracellular Ca2+, preventing excessive circulating renin and hypertension. However, within their native structural organization, the intricacies of intracellular Ca2+ signaling dynamics and their sources remain uncharacterized.

METHODS

We generated mice expressing the JG cell-specific genetically encoded Ca2+ indicator (GCaMP6f) to investigate Ca2+ dynamics within JG cell clusters ex vivo and in vivo. For ex vivo Ca2+ imaging, acutely prepared kidney slices were perfused continuously with a buffer containing variable Ca2+ and AngII concentrations ± Ca2+ channel inhibitors. For in vivo Ca2+ image capture, native mouse kidneys were imaged in situ using multi-photon microscopy with and without AngII administration. ELISA measurements of renin concentrations determined acute renin secretion ex vivo and in vivo, respectively.

RESULTS

Ex vivo Ca2+ imaging revealed that JG cells exhibit robust and coordinated intracellular oscillatory signals with cell-cell propagation following AngII stimulation. AngII dose-dependently induced stereotypical burst patterns characterized by consecutive Ca2+ spikes, which inversely correlated with renin secretion. Pharmacological channel inhibition identified key sources of these oscillations: endoplasmic reticulum Ca2+ storage and release, extracellular Ca2+ uptake via ORAI channels, and intercellular communication through gap junctions. Blocking ORAI channels and gap junctions reduced AngII inhibitory effect on renin secretion. In vivo Ca2+ imaging demonstrated robust intracellular and intercellular Ca2+ oscillations within JG cell clusters under physiological conditions, exhibiting spike patterns consistent with those measured in ex vivo preparations. Administration of AngII enhanced the Ca2+ oscillatory signals and suppressed acute renin secretion in vivo.

CONCLUSION

AngII elicits coordinated intracellular and intercellular Ca2+ oscillations within JG cell clusters, ex vivo and in vivo. The effect is driven by endoplasmic reticulum-derived Ca2+ release, ORAI channels, and gap junctions, leading to suppressed renin secretion.

EFR3A, an Intriguing Gene, and Protein with a Scaffolding Function

The EFR3 (Eighty-Five Requiring 3) protein and its homologs are rather poorly understood eukaryotic plasma membrane peripheral proteins. They belong to the armadillo-like family of superhelical proteins. In higher vertebrates two paralog genes, A and B were found, each expressing at least 2-3 protein isoforms. EFR3s are involved in several physiological functions, mostly including phosphatidyl inositide phosphates, e.g., phototransduction (insects), GPCRs, and insulin receptors regulated processes (mammals). Mutations in the EFR3A were linked to several types of human disorders, i.e., neurological, cardiovascular, and several tumors. Structural data on the atomic level indicate the extended superhelical rod-like structure of the first two-thirds of the molecule with a typical armadillo repeat motif (ARM) in the N-terminal part and a triple helical motif in its C-terminal part. EFR3s' best-known molecular function is anchoring the giant phosphatidylinositol 4-kinase A complex to the plasma membrane crucial for cell signaling, also linked directly to the KRAS mutant oncogenic function. Another function connected to the newly uncovered interaction of EFR3A with flotillin-2 may be the participation of the former in the organization and regulation of the membrane raft domain. This review presents EFR3A as an intriguing subject of future studies.

Astragaloside IV Attenuates Angiotensin II-Induced Inflammatory Responses in Endothelial Cells: Involvement of Mitochondria

Background

Angiotensin II (Ang II)-triggered endothelial inflammation is a critical mechanism contributing to Ang II-related cardiovascular diseases. The inflammation is highly correlated with mitochondrial function. Although astragaloside IV (AS-IV), a primary bioactive ingredient extracted from the traditional Chinese medicine Astragalus membranaceus Bunge that can effectively treat numerous cardiovascular diseases, posses the actions of antiinflammation and antioxidation in vivo, limited data are made available on the impacts of AS-IV on mitochondrial function in endothelial inflammation triggered by Ang II. This study was performed to evaluate the in vitro actions of AS-IV on Ang II-triggered inflammatory responses in endothelial cells, and to further clarify the potential role of mitochondria in the actions.

Methods

Human umbilical vein endothelial cells (HUVECs) were preincubated with AS-IV and then exposed to Ang II for 12 h.

Results

The exposure of HUVECs to Ang II triggered cytokine and chemokine production, the upregulation of adhesive molecules, monocyte attachment, and nuclear factor-kappa B activation. Additionally, our results showed that the inflammatory responses triggered by Ang II were associated with the impairment of mitochondrial function, as evidenced by the reductions of mitochondrial membrane potential, ATP synthesis, and mitochondrial complexes I and III activities. Moreover, the concentrations of malondialdehyde, cellular reactive oxygen species, and mitochondrial superoxide enhanced after HUVECs challenged with Ang II, which were concurrent with the decreases in total superoxide dismutase (SOD) and its isoenzyme activities such as Mn-SOD. These Ang II-induced alterations were reversed by preincubation with AS-IV.

Conclusion

Our data indicate that AS-IV attenuates Ang II-triggered endothelial inflammation possibly via ameliorating mitochondrial function.

The influence of PM2.5 exposure on SARS-CoV-2 infection via modulating the expression of angiotensin converting enzyme II

Particulate matter 2.5 (PM2.5) pollution and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic are the greatest environmental health issues worldwide. Several statistics revealed the significant positive correlation between the morbidity of coronavirus disease-19 (COVID-19) and the levels of air pollution. Nevertheless, there is no direct experimental evidence to indicate the effect of PM2.5 exposure on SARS-CoV-2 infection. The objective of this study was to evaluate whether the infection of SARS-CoV-2 affected by PM2.5 through angiotensin-converting enzyme II (ACE2) expression enhances and investigate the function of ACE2 in lung injury induced by PM2.5. An animal model of PM2.5-induced lung injury was established using wild-type (WT, C57BL/6), human ACE2 transgenic (K18-hACE2 TG), and murine ACE2 gene knockout (mACE2 KO) mice. The results indicate that PM2.5 exposure facilitates SARS-CoV-2 infection through inducing ACE2 expression in vitro (10 μg/mL) and in vivo (6.25 mg/kg/day in 50 μL saline). The levels of ACE, inflammatory cytokines, and mitogen-activated protein kinase (MAPK) proteins in WT, K18-hACE TG and mACE2 KO mice were significantly increased after PM2.5 instillation. The severest PM2.5-induced lung damage was observed in mACE2 KO mice. In summary, ACE2 plays a double-edged sword role in lung injury, PM2.5 exposure contributed to SARS-CoV-2 infection through inducing ACE2 expression, but ACE2 also protected pulmonary inflammation from PM2.5 challenge.

Inflammation pathways as therapeutic targets in angiotensin II induced atrial fibrillation

Atrial fibrillation (AF), a common cardiac arrhythmia, is associated with severe complications such as stroke and heart failure. Although the precise mechanisms underlying AF remain elusive, inflammation is acknowledged as a pivotal factor in its progression. Angiotensin II (AngII) is implicated in promoting atrial remodeling and inflammation. However, the exact pathways through which AngII exacerbates AF are still not fully defined. This study explores the key molecular mechanisms involved, including dysregulation of calcium ions, altered connexin expression, and activation of signaling pathways such as TGF-β, PI3K/AKT, MAPK, NF-κB/NLRP3, and Rac1/JAK/STAT3. These pathways are instrumental in contributing to atrial fibrosis, electrical remodeling, and increased susceptibility to AF. Ang II-induced inflammation disrupts ion channel function, resulting in structural and electrical remodeling of the atria and significantly elevating the risk of AF. Anti-inflammatory treatments such as RAAS inhibitors, colchicine, and statins have demonstrated potential in reducing the incidence of AF, although clinical outcomes are inconsistent. This manuscript underscores the link between AngII-induced inflammation and the development of AF, proposing the importance of targeting inflammation in the management of AF.

Repositioning Perindopril for Mitigation of Methotrexate-Induced Hepatotoxicity in Rats

Background/Objectives: Methotrexate is a folate antagonist that has proven efficacy as an anticancer and immunomodulatory agent. However, the possible incidence of overt hepatotoxicity represents a challenge for its clinical use. Up till now, no single remedy has been considered an effective solution to this important adverse effect. Perindopril is an angiotensin-converting enzyme inhibitor that is widely used for the treatment of hypertension. Due to the involvement of the renin-angiotensin system in the pathogenesis of methotrexate-elicited hepatotoxicity, investigating the efficacy of perindopril in this condition may be of particular interest. The current work aimed at an evaluation of the potential effects of perindopril in a rat model of methotrexate-induced hepatotoxicity and tried to precisely determine the molecular mechanisms that may represent the basis of these effects. Methods: In a model of methotrexate-elicited hepatotoxicity in male Wistar rats, the effects of different doses of perindopril were evaluated at the level of the biochemical measurements and the morphological examination. Results: Oral administration of perindopril to methotrexate-injected rats exhibited a dose-dependent significant improvement in daily food intake; the restoration of the functions of hepatocytes; the potentiation of antioxidant defense mechanisms; the abrogation of the different signaling pathways involved in liver inflammation, apoptosis, and fibrosis; and an enhancement in AMPK/mTOR-driven autophagy when compared to animals that received only a methotrexate injection. These events were reflected in the morphological appearance of the different studied groups. Conclusions: This study presents perindopril as a promising remedy for mitigation of the hepatotoxic effects that occur as a consequence of treatment with methotrexate.

Vascular actions of Ang 1-7 and Ang 1-8 through EDRFs and EDHFs in non-diabetes and diabetes mellitus

The renin-angiotensin system (RAS) plays a pivotal role in regulating vascular homeostasis, while angiotensin 1-8 (Ang 1-8) traditionally dominates as a vasoconstrictor factor. However, the discovery of angiotensin 1-7 (Ang 1-7) and Ang 1-8 has revealed counter-regulatory mechanisms mediated through endothelial-derived relaxing factors (EDRFs) and endothelial-derived hyperpolarizing factors (EDHFs). This review delves into the vascular actions of Ang 1-7 and Ang 1-8 in both non-diabetes mellitus (non-DM) and diabetes mellitus (DM) conditions, highlighting their effects on vascular endothelial cell (VECs) function as well. In a non-DM vasculature context, Ang 1-8 demonstrate dual effect including vasoconstriction and vasodilation, respectively. Additionally, Ang 1-7 induces vasodilation upon nitric oxide (NO) production as a prominent EDRFs in distinct mechanisms. Further research elucidating the precise mechanisms underlying the vascular actions of Ang 1-7 and Ang 1-8 in DM will facilitate the development of tailored therapeutic interventions aimed at preserving vascular health and preventing cardiovascular complications.

Elucidating emerging signaling pathways driving endothelial dysfunction in cardiovascular aging

The risk for developing cardiovascular diseases dramatically increases in older individuals, and aging vasculature plays a crucial role in determining their morbidity and mortality. Aging disrupts endothelial balance between vasodilators and vasoconstrictors, impairing function and promoting pathological vascular remodeling. In this Review, we discuss the impact of key and emerging molecular pathways that transduce aberrant inflammatory signals (i.e., chronic low-grade inflammation-inflammaging), oxidative stress, and mitochondrial dysfunction in aging vascular compartment. We focus on the interplay between these events, which contribute to generating a vicious cycle driving the progressive alterations in vascular structure and function during cardiovascular aging. We also discuss the primary role of senescent endothelial cells and vascular smooth muscle cells, and the potential link between vascular and myeloid cells, in impairing plaque stability and promoting the progression of atherosclerosis. The aim of this summary is to provide potential novel insights into targeting these processes for therapeutic benefit.

Enhanced vascular contraction induced by exposure to angiotensin II mediated by endothelin-1 biosynthesis following PKCβ activation

Protein kinase C (PKC) reportedly plays a role in the pathogenesis of many vascular dysfunction-related conditions. In this study, we investigated whether PKCβ is associated with vascular contractile changes induced by angiotensin II (Ang II) exposure. Long-term (24 h) treatment of rat aortae and mesenteric arteries in Ang II-containing culture medium enhanced 5-hydroxytryptamine (5-HT)-induced vascular contraction in a dose-dependent manner, in association with enhanced phosphorylation of PKCβ S660. Increased contraction induced by Ang II treatment was also observed in endothelium-denuded aorta. Enhanced contraction induced by Ang II was markedly diminished by the knockout of the PKCβ gene or treatment with LY333531 and CGP53353 (PKCβ inhibitors). Cycloheximide (protein synthesis inhibitor) blocked the Ang II-induced enhanced contraction. Gene expression profiling and real-time PCR analyses showed marked upregulation of endothelin-1 (ET-1) expression in Ang II-treated aorta but was not observed in PKCβ-knockout aorta. Ang II increased the secretion of ET-1 peptide in endothelium-intact and -denuded aortae. Ang II-induced enhancement of vascular contraction was diminished by BQ-123 (ETAR blocker). In vivo treatment with Ang II (250 ng/kg/min) for 7 days increased phosphorylation of PKCβ S660 in rat vascular tissue and increased the in vitro contractile responses to 5-HT and in vivo systolic blood pressure, but these changes were largely absent in PKCβ-knockout experiments. These data suggest that long-term exposure to Ang II increases vascular smooth muscle contraction and blood pressure elevation, mediated by activation of PKCβ and subsequent biosynthesis of ET-1 in vascular smooth muscle cells.NEW & NOTEWORTHY We studied the role of PKCβ in Ang II-induced hypertension using a rat model. Our study showed that PKCβ plays a key role in Ang II-induced vascular hypercontractility. Our results also suggest that transcriptional activation-mediated ET-1 expression in vascular smooth muscle is responsible for this vascular change as a downstream pathway of PKCβ activation, which leads to blood pressure elevation. This Ang II-PKCβ-ET-1 mechanism may affect vascular homeostasis in hypertension.

Animal Models for Studying Developmental Origins of Cardiovascular-Kidney-Metabolic Syndrome

Cardiovascular-kidney-metabolic syndrome (CKMS) has become a significant global health challenge. Since CKMS often originates early in life, as outlined by the developmental origins of health and disease (DOHaD) concept, prevention is a more effective strategy than treatment. Various animal models, classified by environmental exposures or mechanisms, are used to explore the developmental origins of CKMS. However, no single model can fully replicate all aspects of CKMS or its clinical stages, limiting the advancement of preventive and therapeutic strategies. This review aims to assist researchers by comparing the strengths and limitations of common animal models used in CKMS programming studies and highlighting key considerations for selecting suitable models.

Angiotensin Dysregulation in Patients with Arterial Aneurysms

Besides playing a critical role in maintaining cardiovascular homeostasis, the renin-angiotensin-aldosterone system (RAS) has been strongly implicated in (aortic) aneurysm pathogenesis. This study aims to investigate systemic and local levels of angiotensin (Ang) and its metabolites in patients with arterial aneurysms, predominantly abdominal aortic aneurysms, using advanced biochemical profiling techniques to provide new insights into the involvement of RAS in aneurysm genesis. A prospective, single-center study was conducted between October 2023 and July 2024. Serum Ang metabolite levels were measured using RAS Fingerprint technology. Aortic tissue samples were analyzed for local RAS activity, including Ang levels and enzyme activity. Additionally, pre- and postoperative serum samples were obtained in a select group of patients. In total, 37 aneurysm patients and 56 controls were included. Aneurysm patients exhibited higher systemic levels of nearly all Ang metabolites compared to controls, with significant differences in Ang I (p = 0.002), Ang II (p = 0.047), Ang 1-5 (p = 0.004), and Renin (p = 0.014) in patients without pharmacological RAS interference. Aneurysm patients receiving ACE inhibitors showed lower serum concentrations in ACE2 activity (p = 0.042) and increased Ang IV levels (p = 0.049) compared to controls. Postoperative measurements indicated different dynamics regarding angiotensin metabolite changes in patients with or without ACE inhibition. This study provides the first comprehensive characterization of RAS profiles in aneurysm patients. These findings add to the body of evidence regarding associations between of RAS and the pathogenesis of arterial aneurysms.

Dan-shen Yin attenuates myocardial fibrosis after myocardial infarction in rats: Molecular mechanism insights by integrated transcriptomics and network pharmacology analysis and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Dan-shen Yin (DSY) originated from the "Shi Fang Ge Kuo" is a Chinese formula composed of three medicines: Salvia miltiorrhiza (Dan-shen), Santalum album L. (Tan-xiang) and Amomum villosum Lour. (Sha-ren). It has many years of clinical experience in the prevention of myocardial fibrosis (MF). However, the specific mechanism of DSY in prevent MF is not clear.

AIM OF THE STUDY

This study aimed to assess the efficacy of DSY in the prevention of MF and reveal its underlying mechanism in a rat model of MF after myocardial infarction (MI) induced by ligation of the left anterior descending branch (LAD) of the coronary artery.

MATERIALS AND METHODS

The blood-entry components of DSY were analyzed by UHPLC-Q-TOF-MS/MS. LAD-ligated rats were used to assess the efficacy of DSY in the prevention of MF. Network pharmacology and transcriptomics analysis were used to predict possible target signaling pathways of DSY in MF. Echocardiography, immunohistochemistry and ELISA methods were used to evaluate the cardiac functions and biochemical changes of the rats. The mRNA expressions of target genes were measured by RT-qPCR. The proteins expressions, including Collagen I, Collagen III, α-smooth muscle actin (α-SMA), matrix metallopeptidase 2 (MMP 2), matrix metallopeptidase 9 (MMP 9), transforming growth factor-β (TGF-β), protein kinase B (AKT), phospho-AKT, extracellular regulated protein kinases (ERK), phospho-ERK, c-Jun N-terminal kinase (JNK), phospho-JNK, mothers against decapentaplegic protein (Smad3), and phospho-Smad3 were detected and quantified by Western Blot.

RESULTS

UHPLC-Q-TOF-MS/MS analysis disclosed that 20 components within DSY could be absorbed into blood of rats. DSY improved myocardial injury in the myocardial tissue of LAD-ligated rats, as evidenced by the elevation of left ventricular ejection fraction and left ventricular fractional shortening, and the decrease of the serum CK-MB and LDH levels. Network pharmacology and transcriptomics predicted that DSY could interfere biological processes, such as extracellular matrix organization, focal adhesion and ECM-receptor interaction, and modulate TGF-β mediated signaling pathways, including PI3K/AKT, MAPK, and Smad3. Further study confirmed that DSY reduced MF, accompanied by reduced TGF-β, Collagen I, Collagen III, α-SMA, MMP 2 and MMP 9. Moreover, DSY repressed the phosphorylation of AKT, MAPKs and Smad3. In addition, DSY reduced inflammation and suppressed the mRNA expressions of IL-1β, IL-6, TNF-α, COX2 and iNOS in MF rats.

CONCLUSIONS

Our study demonstrated that DSY prevented MF in vivo, the action of which was probably via reducing extracellular matrix organization, focal adhesion ECM-receptor interaction and inflammation by regulating TGF-β mediated PI3K/AKT, MAPK and Smad signaling pathways.

The impact of the COVID-19 pandemic on adverse events associated with ACEIs and ARBs: a real-world analysis using the FDA adverse event reporting system

BACKGROUND

During the 2019 coronavirus disease (COVID-19) pandemic, although patients were advised to continue using angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), it remains unclear whether the pandemic influenced the occurrence of adverse reactions to these drugs. This study aims to analyze and compare changes in ACEIs and ARBs adverse events before and during the COVID-19 pandemic, exploring its potential impact on the safety of these medications.

METHODS

We used real-world data to explore the impact of the COVID-19 pandemic on adverse events related to ACEIs and ARBs.

RESULTS

During the pandemic, ACEI-related adverse events (70 cases) and ARB-related adverse events (7 cases) showed increased reporting rates and RORs, with a notable rise in ACEI-related ear and labyrinth disorders. Additionally, 170 new adverse event signals were detected for ACEIs (8 with significantly increased risk) and 191 signals for ARBs (2 with significantly increased risk).

CONCLUSIONS

This study, based on real-world data, revealed significant signals indicating that ACEI use during the COVID-19 pandemic may have increased the risk of renal adverse events and ear labyrinth diseases. The study emphasized the need for increased caution when using ACEIs and ARBs during the pandemic.

Supplementation with the Postbiotic BPL1™-HT (Heat-Inactivated Bifidobacterium animalis subsp. Lactis) Attenuates the Cardiovascular Alterations Induced by Angiotensin II Infusion in Mice

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.

Cancer Stem Cells and the Renin-Angiotensin System in the Tumor Microenvironment of Melanoma: Implications on Current Therapies

Multiple signaling pathways are dysregulated in melanoma, notably the Ras/RAF/MAPK/ERK and PI3K/AKT/mTOR pathways, which can be targeted therapeutically. The high immunogenicity of melanoma has been exploited using checkpoint inhibitors. Whilst targeted therapies and immune checkpoint inhibitors have improved the survival of patients with advanced melanoma, treatment resistance, their side effect profiles, and the prohibitive cost remain a challenge, and the survival outcomes remain suboptimal. Treatment resistance has been attributed to the presence of cancer stem cells (CSCs), a small subpopulation of pluripotent, highly tumorigenic cells proposed to drive cancer progression, recurrence, metastasis, and treatment resistance. CSCs reside within the tumor microenvironment (TME) regulated by the immune system, and the paracrine renin-angiotensin system, which is expressed in many cancer types, including melanoma. This narrative review discusses the role of CSCs and the paracrine renin-angiotensin system in the melanoma TME, and its implications on the current treatment of advanced melanoma with targeted therapy and immune checkpoint blockers. It also highlights the regulation of the Ras/RAF/MAPK/ERK and PI3K/AKT/mTOR pathways by the renin-angiotensin system via pro-renin receptors, and how this may relate to CSCs and treatment resistance, underscoring the potential for improving the efficacy of targeted therapy and immunotherapy by concurrently modulating the renin-angiotensin system.

Sodium valproate reverses aortic hypercontractility in acute myocardial infarction in rabbits

Sympathetic nervous system (SNS), endothelin 1 (ET-1) and angiotensin II (Ang II) are involved in the pathophysiology of acute myocardial infarction (AMI). Valproic acid (VPA) is under study for the treatment against AMI due to its beneficial cardiac effects. However, the vascular effects of VPA on the activation of the SNS, ET-1 and Ang II after AMI are not fully studied. In our study, we used aorta from New Zealand White rabbits without AMI, with AMI and AMI treated with VPA (500 mg/kg/day). AMI was induced by occluding the left circumflex coronary artery for 1 h, followed by reperfusion. After 5 weeks, we studied the ex vivo vascular reactivity in organ bath and measured protein expression by Western blot. Our findings indicated that AMI increased vasoconstriction to exogenous and endogenous NE and ET-1, which was reversed by VPA eliciting upregulation of α2-adrenergic and ETB receptors and downregulating ETA receptors. Although no changes in the vascular response to Ang II were observed in AMI or VPA-treated rabbits, an increase in Ang II type 2 receptor expression was found in VPA-treated rabbits. We conclude that VPA could be considered a vascular protector by modulating SNS, ET-1 and Ang II in the aorta, which together with its cardioprotective effect would make it a promising candidate for the treatment of AMI.

Senolytic Treatment Alleviates Corneal Allograft Rejection Through Upregulation of Angiotensin-Converting Enzyme 2 (ACE2)

Purpose

Allograft rejection remains a major cause of failure in high-risk corneal transplants, but the underlying mechanisms are not fully understood. This study aimed to investigate the contribution of transplantation stress-induced cellular senescence to corneal allograft rejection and to elucidate the associated molecular mechanisms.

Methods

Age-matched murine corneal transplantation models were established. Cellular senescence was evaluated using senescence-associated β-galactosidase (SA-β-Gal) staining, western blot, and immunofluorescence staining. The role of cellular senescence in corneal allograft rejection was analyzed using p16 knockout mice and adoptive transfer experiments. Senolytic treatment with ABT-263 was administered intraperitoneally to evaluate its effects on corneal allograft rejection. RNA sequencing and pharmacological approaches were employed to identify the underlying mechanisms.

Results

Surgical injury induced a senescence-like phenotype in both donor corneas and recipient corneal beds, characterized by an increased accumulation of SA-β-Gal-positive cells in the corneal endothelium and stroma and elevated expression of senescence markers p16 and p21. Using genetic and adoptive transfer models, transplantation stress-induced senescence was shown to exacerbate corneal allograft rejection. Importantly, clearance of senescent cells by ABT-263 significantly suppressed ocular alloresponses and immune rejection. Mechanistically, RNA sequencing and loss-of-function experiments demonstrated that the anti-rejection effects of senolytic treatment were closely dependent on angiotensin-converting enzyme 2 (ACE2).

Conclusions

These findings highlight transplantation stress-induced senescence as a pivotal pathogenic factor in corneal allograft rejection. Senolytic therapy emerges as a potential novel strategy to mitigate transplant rejection and improve corneal allograft survival.

Long-term treatment with the streptococcal exotoxin streptolysin O inhibits vascular smooth muscle contraction by inducing iNOS expression in endothelial cells

Streptolysin O (SLO), a bacterial toxin produced by common hemolytic streptococci, including Streptococcus pyogenes and resident microbiota, may be associated with inflammation in the cardiovascular system. We previously reported that short-term treatment with SLO at relatively high concentrations (10-1000 ng/mL) diminished acetylcholine-induced, endothelial-dependent relaxation in a concentration-dependent manner. However, the vascular function effects of long-term exposure to SLO at lower concentrations are poorly understood. In this study, treatment of rat aorta with endothelium with SLO (0.1-10 ng/mL) for 72 hours inhibited contractions in response to norepinephrine and phenylephrine in a concentration-dependent manner, and this effect was abolished by endothelium denudation. We also observed decreased endothelium-dependent relaxation in aorta treated with a lower concentration of SLO (10 ng/mL) for 72 hours. Long-term treatment with SLO (10 ng/mL) increased the expression of inducible nitric oxide synthase (iNOS) in aorta with endothelium but not aorta without endothelium, and the SLO-induced decrease in contraction was restored by treatment with iNOS inhibitors. Pharmacologic and gene-mutant analyses further indicated that SLO-induced vascular dysfunction and iNOS upregulation are mediated through the toll-like receptor 4/NADPH oxidase 2/reactive oxygen species/p38 mitogen-activated protein kinase pathways. In vivo SLO treatment (46.8 pg/kg per minute) for 7 days also diminished vascular contraction and relaxation activity in aorta with endothelium. We concluded that long-term treatment with SLO inhibits vascular contractile responses, primarily due to increased iNOS expression in the endothelium through toll-like receptor 4-mediated pathways. Our present results, together with those of our previous study, suggest that endothelial cells play a key role in the pathophysiologic changes in cardiovascular function associated with long-term exposure to SLO. SIGNIFICANCE STATEMENT: In the present study, we showed that long-term exposure to streptococcal exotoxin streptolysin O (SLO) inhibits agonist-induced contraction in rat aorta with endothelium, driven primarily by elevated nitric oxide synthase production via NADPH oxidase 2-mediated reactive oxygen species production through toll-like receptor 4 activation on endothelial cells. In vivo treatment with SLO for 7 days also diminished vascular contraction and relaxation, providing evidence of possible pathophysiologic roles of SLO in endothelium-dependent vascular homeostasis.

Microinjection of angiotensin II into zebrafish embryos induces transient dilation and elastin disruption of the dorsal aorta

The effects of angiotensin II (AngII) on blood vessel development and remodeling have been extensively investigated in mice and humans. However, its action on the vessels in the zebrafish remains largely unknown. To investigate whether AngII affects vascular morphology in vivo, we administered AngII into the endothelial-specific transgenic reporter zebrafish (Tg[kdrl:EGFP]) at the 1-cell stage. The average dorsal aortic diameter of five serial positions was significantly increased by 20% in AngII-injected zebrafish compared with buffer-injected controls at 5 days post-fertilization. Histological studies in AngII-injected zebrafish at 8 weeks post-fertilization showed that elastic fiber formation was partly attenuated, with enhanced matrix metalloproteinase-2 expression in the dorsal aorta without dilation. These results suggest that AngII induced transient aortic expansion in early larvae and may affect vascular elastic fiber formation in adult zebrafish. The use of the AngII-injected zebrafish model is a potential tool to dissect the mechanisms of disruption of elastic vascular wall formation in the aorta.

Phosphoproteomics for studying signaling pathways evoked by hormones of the renin-angiotensin system: A source of untapped potential

The Renin-Angiotensin System (RAS) is a complex neuroendocrine system consisting of a single precursor protein, angiotensinogen (AGT), which is processed into various peptide hormones, including the angiotensins [Ang I, Ang II, Ang III, Ang IV, Ang-(1-9), Ang-(1-7), Ang-(1-5), etc] and Alamandine-related peptides [Ang A, Alamandine, Ala-(1-5)], through intricate enzymatic pathways. Functionally, the RAS is divided into two axes with opposing effects: the classical axis, primarily consisting of Ang II acting through the AT1 receptor (AT1R), and in contrast the protective axis, which includes the receptors Mas, AT2R and MrgD and their respective ligands. A key area of RAS research is to gain a better understanding how signaling cascades elicited by these receptors lead to either "classical" or "protective" effects, as imbalances between the two axes can contribute to disease. On the other hand, therapeutic benefits can be achieved by selectively activating protective receptors and their associated signaling pathways. Traditionally, robust "hypothesis-driven" methods like Western blotting have built a solid knowledge foundation on RAS signaling. In this review, we introduce untargeted mass spectrometry-based phosphoproteomics, a "hypothesis-generating approach", to explore RAS signaling pathways. This technology enables the unbiased discovery of phosphorylation events, offering insights into previously unknown signaling mechanisms. We review the existing studies which used phosphoproteomics to study RAS signaling and discuss potential future applications of phosphoproteomics in RAS research including advantages and limitations. Ultimately, phosphoproteomics represents a so far underused tool for deepening our understanding of RAS signaling and unveiling novel therapeutic targets.

Spinal AT1R contributes to neuroinflammation and neuropathic pain via NOX2-dependent redox signaling in microglia

Microglia-mediated neuroinflammation demonstrates a crucial act in the progression of neuropathic pain. Oxidative damage induced by reactive oxygen species (ROS) derived from NADPH oxidase (NOX) in microglia drives proinflammatory microglia activation. Recent evidence points to the central renin angiotensin system (RAS) is involved in oxidative stress and neuroinflammation, with the angiotensin converting enzyme/angiotensin II/angiotensin receptor-1 (ACE/Ang II/AT1R) axis promoting inflammation through increased ROS production, counteracted by the ACE2/Ang (1-7)/Mas receptor (MasR) axis. While interventions targeting spinal AT1R have been shown to alleviate nociceptive hypersensitivity; yet the mechanisms remain elusive. Here, we discovered that spared nerve injury (SNI)-induced mechanical allodynia in rats were associated with M1-like microglia activation, oxidative stress and overactivity of ACE/Ang II/AT1R axis in the spinal cord. Increased AT1R and NOX2 expression were observed in activated dorsal horn microglia following SNI. Blockade of AT1R with losartan potassium (LOP) suppressed NOX2-mediated oxidative stress, and promoted a shift in microglia from the proinflammatory M1 phenotype to the anti-inflammatory M2 phenotype in LPS-treated BV-2 cells. Additionally, NOX2 overexpression triggered the activation of the high-mobility group box 1/nuclear factor-kappa B (HMGB1/NF-κB) signaling pathway. Intrathecal administration of LOP effectively inhibited SNI-induced NOX2 overactivation in microglia and suppressed the HMGB1/NF-kB pathway, reducing oxidative stress and shifting the microglia polarization from M1 to M2 in the spinal cord, thereby attenuating neuroinflammation and pain hypersensitivity. Collectively, these findings underscore the neuroimmune-modulating effects of spinal AT1R in neuropathic pain, highlighting the regulation of redox homeostasis in microglia via a NOX2 dependent mechanism.

Gpr55 deficiency crucially alters cardiomyocyte homeostasis and counteracts angiotensin II induced maladaption in female mice

BACKGROUND AND PURPOSE

Cannabis stimulates several G-protein-coupled-receptors and causes bradycardia and hypotension upon sustained consumption. Moreover, in vitro studies suggest an interference of cannabinoid-signalling with cardiomyocyte contractility and hypertrophy. We aimed at revealing a functional contribution of the cannabinoid-sensitive receptor GPR55 to cardiomyocyte homeostasis and neurohumorally induced hypertrophy in vivo.

EXPERIMENTAL APPROACH

Gpr55-/- and wild-type (WT) mice were characterized after 28-day angiotensin II (AngII; 1·μg·kg-1 min-1) or vehicle infusion. In isolated adult Gpr55-/- and WT cardiomyocytes, mitochondrial function was assessed under naïve conditions, while cytosolic Ca2+ handling was additionally determined following application of the selective GPR55 antagonist CID16020046.

KEY RESULTS

Gpr55 deficiency did not affect angiotensin II (AngII) mediated hypertrophic growth, yet, especially in females, it alleviated maladaptive pro-hypertrophic and -inflammatory gene expression and improved inotropy and adrenergic responsiveness compared to WT. In-depth analyses implied increased cytosolic Ca2+ concentrations and transient amplitudes, and accelerated sarcomere contraction kinetics in Gpr55-/- myocytes, which could be mimicked by GPR55 blockade with CID16020046 in female WT cells. Moreover, Gpr55 deficiency up-regulated factors involved in glucose and fatty acid transport independent of the AngII challenge, accelerated basal mitochondrial respiration and reduced basal protein kinase (PK) A, G and C activity and phospholemman (PLM) phosphorylation.

CONCLUSIONS AND IMPLICATIONS

Our study suggests GPR55 as crucial regulator of cardiomyocyte hypertrophy and homeostasis presumably by regulating PKC/PKA-PLM and PKG signalling, and identifies the receptor as potential target to counteract maladaptation, adrenergic desensitization and metabolic shifts as unfavourable features of the hypertrophied heart in females.

Exploring the Mechanism of Canmei Formula in Preventing and Treating Recurrence of Colorectal Adenoma Based on Data Mining and Algorithm Prediction

BACKGROUND

The high incidence of recurrence and malignant transformation of colorectal adenoma (CRA) are current issues that need to be addressed in clinical practice. Canmei Formula (CMF) has shown promising results in the prevention and treatment, however, it lacks effective clinical data support and its mechanism of action is not fully elucidated.

OBJECTIVE

The aim of this study is to evaluate the clinical efficacy and safety of CMF in preventing and treating CRA, and to explore its effective chemical components and pharmacological mechanisms.

METHOD

A randomized controlled clinical trial was conducted, with patients diagnosed with CRA within 6 months as the study subjects. After randomization, the patients were divided into a treatment group (receiving CMF granules) or a control group (receiving berberine hydrochloride tablets). The one-year recurrence rate of CRA was used as the key efficacy indicator to assess the effectiveness of CMF in preventing and treating CRA. The chemical components of CMF were identified using the UFLC-Q-TOF-MS/MS combined system. Data mining and the wSDTNBI algorithm were combined to construct a differential expression gene (DEG) - CMF prediction target interaction network for CRA. The core targets of CMF in CRA prevention and treatment were identified through topological analysis, and validated using molecular docking and in vitro experiments.

RESULT

During the period from October 1 2021 to December 31 2023, a total of 228 participants were included in the study. After block randomization, 114 patients were assigned to each group. In the treatment group, 98 patients completed follow-up examinations, with 16 patients (14.0%) exhibiting shedding, Adenoma recurrence was identified in 24 (24.5%) patients through colonoscopy. In the control group, 99 cases completed the follow-up examination, while 15 cases (13.2%) were lost to follow-up. There were 45 cases (45.5%) experienced recurrence of adenomas. During the follow-up period, no cases of colorectal cancer or severe adverse reactions were reported. UFLC-QTOF-MS/MS identification was combined with traditional Chinese medicine database mining to obtain 192 active chemical components of Canmei Formula. Using the wSDTNBI algorithm, 1044 prediction targets were predicted, and 3308 differentially expressed genes of CRA were extracted from the TCGA database. Network topology analysis and bioinformatics analysis were performed on 164 intersecting core targets. Molecular docking and qPCR analysis revealed that CMF downregulates angiotensin II type 1 receptor (AT1R) and regulated interleukin-8 (CXCL8) and matrix metalloproteinase 13 (MMP13) within the REN/Ang II/AT1R axis of the renin-angiotensin signaling pathway, thereby preventing and treating CRA.

CONCLUSION

This small-scale randomized controlled clinical trial showed that CMF granules can safely and effectively reduce the risk of CRA recurrence. CMF prevents and treats colorectal adenomas by modulating the renin-angiotensin signaling pathway and the inflammatory response.

Postoperative Empyema Due to Leclercia adecarboxylata Following Mesothelioma Surgery: A Case Report

BACKGROUND/OBJECTIVES

Leclercia adecarboxylata (L. adecarboxylata) is a rare opportunistic pathogen that can cause severe infections like empyema, particularly in immunocompromised individuals. We aim to highlight the importance of the early detection and personalized treatment of L. adecarboxylata infections in patients with comorbidities such as malignant mesothelioma.

METHODS

We present the case of a 57-year-old man with type 2 diabetes mellitus, hypertension, and malignant mesothelioma who developed a parapneumonic effusion that progressed to empyema. After undergoing pleurectomy and pleurodesis, intraoperative cultures identified L. adecarboxylata. Targeted antibiotic therapy was initiated based on the culture results, and the patient's response was closely monitored.

RESULTS

The patient responded well to targeted antibiotic therapy with ampicillin/sulbactam following the initial empirical treatment with piperacillin/tazobactam. The identification of L. adecarboxylata-a rare finding in empyema cases-was crucial for effective management. The patient recovered fully without complications, highlighting the importance of the early identification and individualized treatment of infections caused by rare pathogens.

CONCLUSIONS

This case underscores the need to consider L. adecarboxylata in immunocompromised patients presenting with unusual infections. Early detection through advanced diagnostic techniques and personalized antibiotic therapy can improve clinical outcomes and help prevent antimicrobial resistance. Increased clinical awareness and further research into the resistance patterns and treatment approaches for L. adecarboxylata are essential to enhance patient care.

Role of GPCR Signaling in Anthracycline-Induced Cardiotoxicity

Anthracyclines are a class of chemotherapeutics commonly used to treat a range of cancers. Despite success in improving cancer survival rates, anthracyclines have dose-limiting cardiotoxicity that prevents more widespread clinical utility. Currently, the therapeutic options for these patients are limited to the iron-chelating agent dexrazoxane, the only FDA-approved drug for anthracycline cardiotoxicity. However, the clinical use of dexrazoxane has failed to replicate expectations from preclinical studies. A limited list of GPCRs have been identified as pathogenic in anthracycline-induced cardiotoxicity, including receptors (frizzled, adrenoreceptors, angiotensin II receptors) previously implicated in cardiac remodeling in other pathologies. The RNA sequencing of iPSC-derived cardiac myocytes from patients has increased our understanding of the pathogenic mechanisms driving cardiotoxicity. These data identified changes in the expression of novel GPCRs, heterotrimeric G proteins, and the regulatory pathways that govern downstream signaling. This review will capitalize on insights from these experiments to explain aspects of disease pathogenesis and cardiac remodeling. These data provide a cornucopia of possible unexplored potential pathways by which we can reduce the cardiotoxic side effects, without compromising the anti-cancer effects, of doxorubicin and provide new therapeutic options to improve the recovery and quality of life for patients undergoing chemotherapy.

A perspective on small molecules targeting the renin-angiotensin-aldosterone system and their utility in cardiovascular diseases: exploring the structural insights for rational drug discovery and development

Renin-angiotensin-aldosterone system (RAAS) is crucial in cardiovascular homeostasis. Any disruption in this homeostasis often leads to numerous cardiovascular diseases (CVDs) and non-cardiovascular diseases. Small molecules that show ability toward mechanically modulating RAAS components have been developed to address this problem, thus providing opportunities for innovative drug discovery and development. This review is put forth to provide a comprehensive understanding not only on the signaling mechanisms of RAAS that lead to cardiovascular events but also on the use of small molecules targeting the modulation of RAAS components. Further, the detailed descriptions of the drugs affecting the RAAS and their pharmacodynamics, kinetics, and metabolism profiles are provided. This article also covers the limitations of the present therapeutic armory, followed by their mechanistic insights. A brief discussion is offered on the analysis of the chemical space parameters of the drugs affecting RAAS compared to other cardiovascular and renal categories of medications approved by the US FDA. This review provides structural insights and emphasizes the importance of integrating the current therapeutic regimen with pharmacological tactics to accelerate the development of new therapeutics targeting the RAAS components for improved and efficacious cardiovascular outcomes. Finally, chemical spacing parameters of RAAS modulators are provided, which will help in understanding their peculiarities in modulating the RAAS signaling through structural and functional analyses. Furthermore, this review will assist medicinal chemists working in this field in developing better drug regimens with improved selectivity and efficacy.

Unveiling the molecular and cellular links between obstructive sleep apnea-hypopnea syndrome and vascular aging

ABSTRACT

Vascular aging (VA) is a common etiology of various chronic diseases and represents a major public health concern. Intermittent hypoxia (IH) associated with obstructive sleep apnea-hypopnea syndrome (OSAHS) is a primary pathological and physiological driver of OSAHS-induced systemic complications. A substantial proportion of OSAHS patients, estimated to be between 40% and 80%, have comorbidities such as hypertension, heart failure, coronary artery disease, pulmonary hypertension, atrial fibrillation, aneurysm, and stroke, all of which are closely associated with VA. This review examines the molecular and cellular features common to both OSAHS and VA, highlighting decreased melatonin secretion, impaired autophagy, increased apoptosis, increased inflammation and pyroptosis, increased oxidative stress, accelerated telomere shortening, accelerated stem cell depletion, metabolic disorders, imbalanced protein homeostasis, epigenetic alterations, and dysregulated neurohormonal signaling. The accumulation and combination of these features may underlie the pathophysiological link between OSAHS and VA, but the exact mechanisms by which OSAHS affects VA may require further investigation. Taken together, these findings suggest that OSAHS may serve as a novel risk factor for VA and related vascular disorders, and that targeting these features may offer therapeutic potential to mitigate the vascular risks associated with OSAHS.

Mechanisms of inflammatory microenvironment formation in cardiometabolic diseases: molecular and cellular perspectives

Cardiometabolic diseases (CMD) are leading causes of death and disability worldwide, with complex pathophysiological mechanisms in which inflammation plays a crucial role. This review aims to elucidate the molecular and cellular mechanisms within the inflammatory microenvironment of atherosclerosis, hypertension and diabetic cardiomyopathy. In atherosclerosis, oxidized low-density lipoprotein (ox-LDL) and pro-inflammatory cytokines such as Interleukin-6 (IL-6) and Tumor Necrosis Factor-alpha (TNF-α) activate immune cells contributing to foam cell formation and arterial wall thickening. Hypertension involves the activation of the renin-angiotensin system (RAS) alongside oxidative stress-induced endothelial dysfunction and local inflammation mediated by T cells. In diabetic cardiomyopathy, a high-glucose environment leads to the accumulation of advanced glycation end products (AGEs), activating the Receptor for Advanced Glycation Endproducts (RAGE) and triggering inflammatory responses that further damage cardiac and microvascular function. In summary, the inflammatory mechanisms in different types of metabolic cardiovascular diseases are complex and diverse; understanding these mechanisms deeply will aid in developing more effective individualized treatment strategies.

Long-Term Effects of COVID-19 on Optic Disc and Retinal Microvasculature Assessed by Optical Coherence Tomography Angiography

Objectives: To evaluate the long-term effects of coronavirus disease (COVID-19) on optic disc and macular microvasculature. Methods: 40 post-COVID-19 and 40 healthy subjects were included. Optical coherence tomography angiography (OCTA) was performed for all subjects at the first visit and repeated in the fourth and twelfth months. Radial peripapillary capillary (RPC) vessel density (VD), retinal nerve fiber layer (RNFL) thickness, foveal avascular zone (FAZ) area, FAZ perimeter, VDs of the fovea, parafovea, and perifovea at superficial capillary plexus (SCP) and deep capillary plexus (DCP), and central macular thickness (CMT) were evaluated. The OCTA measurements of the COVID-19 group were compared with the control group. Results: The COVID-19 group showed lower VD values than the control group in the nasal parafoveal quadrant of the SCP at all visits (p = 0.009, p = 0.47, p = 0.042) and in the superior perifoveal quadrant of the DCP in the twelfth-month visit (p = 0.014). At all visits, FAZ area and FAZ perimeter were higher (p = 0.02, p = 0.02, p = 0.002; p = 0.002, p = 0.003, p = 0.005), foveal VD values of both SCP and DCP were lower (p < 0.001, p < 0.001, p < 0.001; p = 0.005, p = 0.001, p = 0.001), and CMT was lower (p < 0.001, p = 0.001, p = 0.001) in the COVID-19 group. The COVID-19 group had higher temporal quadrant RPC at all visits (p = 0.003, p = 0.003, p < 0.001) and higher average, superior and inferior RNFL at first and fourth-month visits (p = 0.014, p = 0.020; p = 0.001, p = 0.003; p = 0.021, p = 0.024). Conclusions: There are long-term changes that mainly point to the ischemia in the COVID-19 patients. We emphasize the need for long-term ophthalmologic and systemic follow-up of COVID-19 patients regarding potential complications.

Supplementation with Standardized Green/Black or White Tea Extracts Attenuates Hypertension and Ischemia-Reperfusion-Induced Myocardial Damage in Mice Infused with Angiotensin II

Arterial hypertension has a high prevalence in the population and is considered both a cardiovascular disease and an important risk factor for the development of other cardiovascular diseases. Tea consumption shows antihypertensive effects due to its composition in terms of bioactive substances such as flavan-3-ols and xanthines. The aim of this study was to assess the possible beneficial effects of two tea extracts, one of white tea (ADM® White Tea; WTE) and another one composed of a mixture of black tea and green tea (ADM® Tea Complex; CTE), on the cardiovascular alterations induced by angiotensin II (AngII) infusion in mice. For this purpose, four groups of C57BL/6J male mice were used: (1) mice fed on a standard diet for 8 weeks and infused with saline for the last 4 weeks (controls); (2) mice fed on a standard diet for 8 weeks and infused with AngII for the last 4 weeks (AngII); (3) mice fed on a standard diet supplemented with 1.6% WTE and infused with AngII for the last 4 weeks (AngII + WTE); (4) mice fed on a standard diet supplemented with 1.6% TC and infused with AngII for the last 4 weeks (AngII + CTE). Both tea extracts exerted anti-inflammatory and antioxidant effects in arterial tissue and reduced AngII-induced endothelial dysfunction in aorta segments. Moreover, supplementation with WTE or CTE reduced the Ang-II-induced overexpression of AT1R and increased AngII-induced downregulation of AT2R in arterial tissue. However, only supplementation with CTE significantly increased the circulating levels of angiotensin 1-7 and reduced systolic blood pressure. In the heart, supplementation with both tea extracts attenuated AngII-induced cardiac hypertrophy and reduced ischemia-reperfusion-induced oxidative stress and apoptosis in myocardial tissue. In conclusion, supplementation with WTE or CTE attenuates AngII-induced cardiovascular damage through their anti-inflammatory, antioxidant, and antiapoptotic effects. In addition, supplementation with CTE also exerts antihypertensive effects, and so it may constitute an avenue through which to support cardiovascular health.

Accuracy study of Angiotensin 1-7 composite index test to predict pulmonary fibrosis and guide treatment

BACKGROUND

Pulmonary fibrosis can develop after acute respiratory distress syndrome (ARDS). The hypothesis is we are able to measure phenotypes that lie at the origin of ARDS severity and fibrosis development. The aim is an accuracy study of prognostic circulating biomarkers.

METHODS

A longitudinal study followed COVID-related ARDS patients with medical imaging, pulmonary function tests and biomarker analysis, generating 444 laboratory data. Comparison to controls used non-parametrical statistics; p < 0·05 was considered significant. Cut-offs were obtained through receiver operating curve. Contingency tables revealed predictive values. Odds ratio was calculated through logistic regression.

RESULTS

Angiotensin 1-7 beneath 138 pg/mL defined Angiotensin imbalance phenotype. Hyper-inflammatory phenotype showed a composite index test above 34, based on high Angiotensin 1-7, C-Reactive Protein, Ferritin and Transforming Growth Factor-β. Analytical study showed conformity to predefined goals. Clinical performance gave a positive predictive value of 95 % (95 % confidence interval, 82 %-99 %), and a negative predictive value of 100 % (95 % confidence interval, 65 %-100 %). Those severe ARDS phenotypes represented 34 (Odds 95 % confidence interval, 3-355) times higher risk for pulmonary fibrosis development (p < 0·001).

CONCLUSIONS

Angiotensin 1-7 composite index is an early and objective predictor of ARDS evolving to pulmonary fibrosis. It may guide therapeutic decisions in targeted phenotypes.

Transgenic rat with ubiquitous expression of angiotensin-(1-7)-producing fusion protein: a new tool to study the role of protective arm of the renin-angiotensin system in the pathophysiology of cardio-renal diseases

The aim of the present study was to assess systemic circulatory and tissue activities of both the classical arm and of the alternative arm of the renin-angiotensin system (RAS) in a new transgenic rat line (TG7371) that expresses angiotensin-(1-7) (ANG 1-7)-producing fusion protein; the results were compared with the activities measured in control transgene-negative Hannover Sprague-Dawley (HanSD) rats. Plasma and tissue concentrations of angiotensin II (ANG II) and ANG 1-7, and kidney mRNA expressions of receptors responsible for biological actions of ANG II and ANG 1-7 [i.e. ANG II type 1 and type 2 (AT1 and AT2) and Mas receptors] were assessed in TG7371 transgene-positive and in HanSD rats. We found that male TG7371 transgene-positive rats exhibited significantly elevated plasma, kidney, heart and lung ANG 1-7 concentrations as compared with control male HanSD rats; by contrast, there was no significant difference in ANG II concentrations and no significant differences in mRNA expression of AT1, AT2 and Mas receptors. In addition, we found that in male TG7371 transgene-positive rats blood pressure was lower than in male HanSD rats. These data indicate that the balance between the classical arm and the alternative arm of the RAS was in male TGR7371 transgene-positive rats markedly shifted in favor of the latter. In conclusion, TG7371 transgene-positive rats represent a new powerful tool to study the long-term role of the alternative arm of the RAS in the pathophysiology and potentially in the treatment of cardio-renal diseases.

Modulation of Angiotensin-II and Angiotensin 1-7 Levels Influences Cardiac Function in Myocardial Ischemia-reperfusion Injury

The angiotensin-converting enzyme-2 (ACE-2) alters the pathophysiology of various fatal cardiovascular diseases, including ischemic heart disease, whereas angiotensin 1-7 (Ang 1-7) exerts a wide range of actions. The effects of ischemia-reperfusion (IR) injury include damage to myocardial tissue that initiates protease action, causing cardiac cell death. Angiotensin- II (Ang-II) contributes through the renin-angiotensin system (RAS) to the IR injury, whereas Ang 1-7 paradoxically exerts a protective effect through the same. Thus, the myocardial ischemic reperfusion injury (MIRI) may be altered by the RAS of the heart. This review paper focuses on ACE-2, angiotensin-converting enzyme (ACE), and Ang 1-7 regulation in the RAS of the heart in the pathophysiology of MIRI. The treatment in such conditions using ACE-2 activator, ACE inhibitor, and Ang-II antagonists may promote vascular functions as well as cardio- protection.

Direct Vascular Effects of Angiotensin II (A Systematic Short Review)

The octapeptide angiotensin II (Ang II) is a circulating hormone as well as a locally formed agonist synthesized by the angiotensin-converting enzyme (ACE) of endothelial cells. It forms a powerful mechanism to control the amount and pressure of body fluids. All main effects are directed to save body salt and water and ensure blood pressure under basic conditions and in emergencies. All blood vessels respond to stimulation by Ang II; the immediate response is smooth muscle contraction, increasing vascular resistance, and elevating blood pressure. Such effects are conveyed by type 1 angiotensin receptors (AT1Rs) located in the plasma membrane of both endothelial and vascular smooth muscle cells. AT1Rs are heterotrimeric G protein-coupled receptors (GPCRs), but their signal pathways are much more complicated than other GPCRs. In addition to Gq/11, the G12/13, JAK/STAT, Jnk, MAPK, and ERK 1/2, and arrestin-dependent and -independent pathways are activated because of the promiscuous attachment of different signal proteins to the intracellular G protein binding site and to the intracellular C terminal loop. Substantial changes in protein expression follow, including the intracellular inflammation signal protein NF-κB, endothelial contact proteins, cytokines, matrix metalloproteinases (MMPs), and type I protocollagen, eliciting the inflammatory transformation of endothelial and vascular smooth muscle cells and fibrosis. Ang II is an important contributor to vascular pathologies in hypertensive, atherosclerotic, and aneurysmal vascular wall remodeling. Such direct vascular effects are reviewed. In addition to reducing blood pressure, AT1R antagonists and ACE inhibitors have a beneficial effect on the vascular wall by inhibiting pathological wall remodeling.

Hypertension: A Continuing Public Healthcare Issue

Hypertension is a cardiovascular disease defined by an elevated systemic blood pressure. This devastating disease afflicts 30-40% of the adult population worldwide. The disease burden for hypertension is great, and it greatly increases the risk of cardiovascular morbidity and mortality. Unfortunately, there are a myriad of factors that result in an elevated blood pressure. These include genetic factors, a sedentary lifestyle, obesity, salt intake, aging, and stress. Although lifestyle modifications have had limited success, anti-hypertensive drugs have been moderately effective in lowering blood pressure. New approaches to control and treat hypertension include digital health tools and compounds that activate the angiotensin receptor type 2 (AT2), which can promote cardiovascular health. Nonetheless, research on hypertension and its management is vital for lessening the significant health and economic burden of this condition.

Melatonin attenuates responses to angiotensin II in isolated aortic rings of STZ-induced type 1-like DM rats

BACKGROUND

In patients with diabetes mellitus (DM), vascular endothelial dysfunction (VED) is the main reason for impaired life expectancy. Melatonin (MEL) demonstrates wide-ranging effects across various organs and exhibits pleiotropic characteristics. The current study aims to investigate the modulatory roles of MEL vascular response to angiotensin II (Ang II) and its receptors including angiotensin type 1 receptor (AT-1 R) and angiotensin type 2 receptor (AT-2 R) in isolated thoracic aorta of non-diabetes (non-DM) and diabetes (DM) rats.

METHODS

The thoracic aortae were isolated in order to investigate the influence of MEL on AT-1 R, using valsartan (VAL) and MT-2Rusing luzindole (LUZ) via dose-response curve (DRC) measurement of Ang II reactivity. In addition, AT-1 R was involved in this study, under PD123319 with ADInstrument organ bath (Panlab apparatus, Harvard University, USA).

RESULTS

The maximum response of Ang II was increased significantly in DM condition. In addition, AT-1 R was completely blocked under VAL, while AT-2 R was upregulated in the DM group. The combination of VAL and PD123319 led to abolishing the Ang II effect dramatically as well. Melatonin alone reduced Ang II in the DM group dramatically. This effect was also observed with MEL, PD1213319, and VAL combination, as well as, with MEL, LUZ, and PD1213319 combination.

CONCLUSIONS

Melatonin has been demonstrated to modulate both AT-1 R and AT-2 R and has influenced the reactivity of Ang II in the aortas of diabetic rats through highly complex mechanisms.

Muscle mass, muscle strength and the renin-angiotensin system

The renin-angiotensin system (RAS) is a classically known circulatory regulatory system. In addition to the previously known multi-organ circulatory form of the RAS, the existence of tissue RASs in individual organs has been well established. Skeletal muscle has also been identified as an organ with a distinct RAS. In recent years, the effects of RAS activation on skeletal muscle have been elucidated from several perspectives: differences in motor function due to genetic polymorphisms of RAS components, skeletal muscle dysfunction under conditions of excessive RAS activation such as heart failure, and the effects of the use of RAS inhibitors on muscle strength. In addition, the concept of the RAS itself has recently been expanded with the discovery of a 'protective arm' of the RAS formed by factors such as angiotensin-converting enzyme 2 and angiotensin 1-7. This has led to a new understanding of the physiological function of the RAS in skeletal muscle. This review summarizes the diverse physiological functions of the RAS in skeletal muscle and considers the potential of future therapeutic strategies targeting the RAS to overcome problems such as sarcopenia and muscle weakness associated with chronic disease.

Fasting recovers age-related hypertension in the rats: reset of renal renin-angiotensin system components and klotho

BACKGROUND

The renal renin-angiotensin system (RAS) plays a vital part in the control of blood pressure and is known to be affected by aging. This study aimed to investigate the effects of intermittent fasting on age-related hypertension and the expression of local renal RAS components.

METHODS

The Wistar rats were categorized into three main age groups (young, middle aged, and elderly) and three dietary treatment models, including ad libitum feeding (AL), every other day fasting (EOD), and one day per week of fasting (FW). After three months, blood pressure (BP) was assessed. Some genes and proteins of the renal RAS system were measured by using Real time PCR and Western blot. α-klotho and Ang II proteins were assessed by ELISA method.

RESULTS

Old rats exhibited significantly increase in BP and Ang II (P < 0.001 vs. young rats) and a significant reduction in circulating levels of α-klotho and kidney AT2R protein (P < 0.001, P < 0.01, vs. young rats, respectively). Additionally, they respond to aging by increasing the AT1aR/AT2R proteins ratio (P < 0.05). Two model of feeding reduced BP in old rats and circulating Ang II in middle-aged and older rats. Moreover, by fasting, ACE2 protein expression was elevated in old rats. EOD fasting also significantly elevated the AT2 receptor protein and reduced the AT1aR/AT2R proteins ratio in the older rats (P < 0.001, P < 0.01, respectively).

CONCLUSION

Our findings suggest that fasting, particularly EOD, can attenuate age-related hypertension, partly through reset of the local renal RAS and increase of klotho protein expression.

Angiotensin peptides enhance SARS-CoV-2 spike protein binding to its host cell receptors

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the virus that caused the Coronavirus Disease 2019 (COVID-19) pandemic, has a spike glycoprotein that is involved in recognizing and fusing to host cell receptors, such as angiotensin-converting enzyme 2 (ACE2), neuropilin-1 (NRP1), and AXL tyrosine-protein kinase. Since the major spike protein receptor is ACE2, an enzyme that regulates angiotensin II (1-8), this study tested the hypothesis that angiotensin II (1-8) influences the binding of the spike protein to its receptors. While angiotensin II (1-8) did not influence spike-ACE2 binding, we found that it significantly enhances spike-AXL binding. Our experiments showed that longer lengths of angiotensin, such as angiotensin I (1-10), did not significantly affect spike-AXL binding. In contrast, shorter lengths of angiotensin peptides, in particular, angiotensin IV (3-8), strongly increased spike-AXL binding. Angiotensin IV (3-8) also enhanced spike protein binding to ACE2 and NRP1. The discovery of the enhancing effects of angiotensin peptides on spike-host cell receptor binding may suggest that these peptides could be pharmacological targets to treat COVID-19 and post-acute sequelae of SARS-CoV-2 (PASC), which is also known as long COVID.

Protease-activated receptor 2 deficient mice develop less angiotensin II induced left ventricular hypertrophy but more cardiac fibrosis

AIMS

Activation of Protease Activated Receptor 2 (PAR2) has been shown to be involved in regulation of injury-related processes including inflammation, fibrosis and hypertrophy. In this study we will investigate the role of PAR2 in cardiac injury in a mouse model of hypertension using continuous infusion with angiotensin II.

METHODS

Hypertension was induced in 12 weeks old wildtype (wt, n = 8) and PAR2 deficient mice (n = 9) by continuous infusion with angiotensin II for 4 weeks using osmotic minipumps. At the end, hearts were collected for analysis of left ventricular hypertrophy (LVH), myocardial capillary supply, fibrosis and localization of PAR2 expression using histological, immunohistological and mRNA expression analysis techniques. In addition, rat cardiac fibroblasts were treated with angiotensin II and PAR2 was inhibited by a blocking antibody and the PAR2 inhibitor AZ3451.

RESULTS

Cardiac PAR2 mRNA expression was downregulated by 40±20% in wt mice treated with AngII compared to untreated controls. Four weeks after AngII treatment, LVH was significantly increased in AngII-treated wt mice compared to similarly treated PAR2-deficient animals as determined by relative heart weight, left ventricular cross-sectional area, and analysis of ventricular lumen area determined on sections. Treatment of wt mice resulted in an approximately 3-fold increase in cardiac expression of FGF23, which was 50% lower in PAR2-deficient animals compared to wt animals and therefore no longer significantly different from expression levels in untreated control mice. In contrast, cardiac interstitial fibrosis was significantly higher in PAR2-deficient mice compared to similar treated wt controls, as assessed by Sirius Red staining (>3-fold) and collagen IV staining (>2-fold). Additional experiments with isolated cardiac fibroblasts showed induction of pro-fibrotic genes when treated with PAR2 inhibitors.

CONCLUSION

In angiotensin II-induced cardiac injury, PAR2 deficiency has an ambivalent effect, enhancing fibrosis on the one hand, but reducing LVH on the other.

Pathophysiology of Angiotensin II-Mediated Hypertension, Cardiac Hypertrophy, and Failure: A Perspective from Macrophages

Heart failure is a complex syndrome characterized by cardiac hypertrophy, fibrosis, and diastolic/systolic dysfunction. These changes share many pathological features with significant inflammatory responses in the myocardium. Among the various regulatory systems that impact on these heterogeneous pathological processes, angiotensin II (Ang II)-activated macrophages play a pivotal role in the induction of subcellular defects and cardiac adverse remodeling during the progression of heart failure. Ang II stimulates macrophages via its AT1 receptor to release oxygen-free radicals, cytokines, chemokines, and other inflammatory mediators in the myocardium, and upregulates the expression of integrin adhesion molecules on both monocytes and endothelial cells, leading to monocyte-endothelial cell-cell interactions. The transendothelial migration of monocyte-derived macrophages exerts significant biological effects on the proliferation of fibroblasts, deposition of extracellular matrix proteins, induction of perivascular/interstitial fibrosis, and development of hypertension, cardiac hypertrophy and heart failure. Inhibition of macrophage activation using Ang II AT1 receptor antagonist or depletion of macrophages from the peripheral circulation has shown significant inhibitory effects on Ang II-induced vascular and myocardial injury. The purpose of this review is to discuss the current understanding in Ang II-induced maladaptive cardiac remodeling and dysfunction, particularly focusing on molecular signaling pathways involved in macrophages-mediated hypertension, cardiac hypertrophy, fibrosis, and failure. In addition, the challenges remained in translating these findings to the treatment of heart failure patients are also addressed.

Therapeutic opportunities in targeting the protective arm of the renin-angiotensin system to improve insulin sensitivity: a mechanistic review

In recent years, the knowledge of the physiological and pathophysiological roles of the renin-angiotensin system (RAS) in glucose metabolism has advanced significantly. It is now well-established that blockade of the angiotensin AT1 receptor (AT1R) improves insulin sensitivity. Activation of the AT2 receptor (AT2R) and the MAS receptor are significant contributors to this beneficial effect. Elevated availability of angiotensin (Ang) II) for interaction with the AT2R and increased Ang-(1-7) formation during AT1R blockade mediate these effects. The ongoing development of selective AT2R agonists, such as compound 21 and the novel Ang III peptidomimetics, has significantly advanced the exploration of the role of AT2R in metabolism and its potential as a therapeutic target. These agents show promise, particularly when RAS inhibition is contraindicated. Additionally, other RAS peptides, including Ang IV, des-Asp-Ang I, Ang-(1-9), and alamandine, hold therapeutic capability for addressing metabolic disturbances linked to type 2 diabetes. The possibility of AT2R heteromerization with either AT1R or MAS receptor offers an exciting area for future research, particularly concerning therapeutic strategies to improve glycemic control. This review focuses on therapeutic opportunities to improve insulin sensitivity, taking advantage of the protective arm of the RAS.

Implications of β-Arrestin biased signaling by angiotensin II type 1 receptor for cardiovascular drug discovery and therapeutics

Angiotensin II receptors, Type 1 (AT1R) and Type 2 (AT2R) are 7TM receptors that play critical roles in both the physiological and pathophysiological regulation of the cardiovascular system. While AT1R blockers (ARBs) have proven beneficial in managing cardiac, vascular and renal maladies they cannot completely halt and reverse the progression of pathologies. Numerous experimental and animal studies have demonstrated that β-arrestin biased AT1R-ligands (such as SII-AngII, S1I8, TRV023, and TRV027) offer cardiovascular benefits by blocking the G protein signaling while retaining the β-arrestin signaling. However, these ligands failed to show improvement in heart-failure outcome over the placebo in a phase IIb clinical trial. One major limitation of current β-arrestin biased AT1R-ligands is that they are peptides with short half-lives, limiting their long-term efficacy in patients. Additionally, β-arrestin biased AT1R-ligand peptides, may inadvertently block AT2R, a promiscuous receptor, potentially negating its beneficial effects in post-myocardial infarction (MI) patients. Therefore, developing a small molecule β-arrestin biased AT1R-ligand with a longer half-life and specificity to AT1R could be more effective in treating heart failure. This approach has the potential to revolutionize the treatment of cardiovascular diseases by offering more sustained and targeted therapeutic effects.

Complex of Angiotensin II with Modified Low-Density Lipoproteins: Behavioral and Hemodynamic Effects in Rats

Endogenous multiple modified LDL (mLDL) and the renin-angiotensin system play a significant role in the development of atherosclerosis. It has been found that by behavioral and hemodynamic parameters the physiological activity of angiotensin II (Ang II) in combination with mLDL is considerably modified due to weakening of its diuretic effect and the inversion of hypertensive and tachyarrhythmic effects. Atherosclerosis is a long-term pathological process, so a single administration of artificially synthesized Ang I-mLDL complexes can be considered a model of the first contact of the body with pathogenic factors. We believe that angiotensin complexes with mLDL participate in adaptive and compensatory mechanisms at the initial stages of atherosclerosis and later contribute to its progression.