Search Results (811)

Gastrointestinal (GI) cancers represent a significant global health burden, with high morbidity and mortality often linked to late-stage detection and metastatic disease. The progression of these malignancies is critically driven by angiogenesis, the formation of new blood vessels, and the surrounding dynamic tumor microenvironment (TME), a complex ecosystem comprising various cell types and non-cellular components. This comprehensive review, based on a systematic search of the PubMed database, synthesizes the existing literature to define the intertwined roles of angiogenesis and the TME in GI tumorigenesis. The TME’s influence creates conditions favorable for tumor growth, invasion, and metastasis, but sometimes induces resistance to current therapies. Available therapeutic strategies for inhibiting angiogenesis involve antibodies and oral tyrosine kinase inhibitors, while immune modulation within the tumor microenvironment is mainly achieved through checkpoint inhibitor antibodies and chemotherapy. Creative emerging strategies encompassing cellular therapies, bispecific antibodies, and new targets such as CD40, DLL4, and Ang2, amongst others, are focused on inhibiting proangiogenic pathways more profoundly, reversing resistance to prior drugs, and modulating the TME to enhance therapeutic efficacy. A deeper understanding of the complex interactions between components of the TME is crucial for addressing the unmet need for novel and effective therapeutic interventions against aggressive GI cancers. Full article

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

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

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

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

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

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

Chronic kidney disease (CKD)-associated anemia is a global health concern and is linked to vascular and ocular complications. Hypoxia-inducible factor (HIF) stabilizers, or HIF prolyl hydroxylase inhibitors (PHIs), are promising candidates for the treatment of CKD-associated anemia. Since hypoxia and angiogenesis are involved in eye diseases, this study examined the effects of HIF-PHIs on metabolism and gene expression in retinal pigment epithelium (RPE) cells. Results revealed that PHIs differentially induced angiogenic (VEGFA, ANG) and glycolytic (PDK1, GLUT1) gene expression, with Roxadustat causing the strongest transcriptional changes. However, Roxadustat-induced angiogenic signals did not promote endothelial tube formation. Moreover, it did not induce oxidative stress, inflammation, or significant antioxidant gene responses in ARPE-19 cells. Roxadustat also reduced the inflammatory cytokine response to tumor necrosis factor-α, including IL-6, IL-8, and MCP-1, and did not exacerbate VEGF expression under high-glucose conditions. Overall, Roxadustat triggered complex gene expression changes without promoting inflammation or oxidative stress in RPE cells. Despite these findings, ophthalmologic monitoring is advised during PHI treatment in CKD patients receiving HIF-PHIs. Full article

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

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

Acute heart failure (AHF) is a clinical syndrome characterized by the sudden onset or rapid worsening of heart failure signs and symptoms, frequently triggered by myocardial ischemia, pressure overload, or cardiotoxic injury. A central component of its pathophysiology is the activation of intracellular signal transduction cascades that translate extracellular stress into cellular responses. Among these, the mitogen-activated protein kinase (MAPK) pathways have received considerable attention due to their roles in mediating inflammation, apoptosis, hypertrophy, and adverse cardiac remodeling. The canonical MAPK cascades—including extracellular signal-regulated kinases (ERK1/2), p38 MAPK, and c-Jun N-terminal kinases (JNK)—are activated by upstream stimuli such as angiotensin II (Ang II), aldosterone, endothelin-1 (ET-1), and sustained catecholamine release. Additionally, emerging evidence highlights the role of receptor-mediated signaling, cellular stress, and myeloid cell-driven coagulation events in linking MAPK activation to fibrotic remodeling following myocardial infarction. The phosphatidylinositol 3-kinase (PI3K)/Akt signaling cascade plays a central role in regulating cardiomyocyte survival, hypertrophy, energy metabolism, and inflammation. Activation of the PI3K/Akt pathway has been shown to confer cardioprotective effects by enhancing anti-apoptotic and pro-survival signaling; however, aberrant or sustained activation may contribute to maladaptive remodeling and progressive cardiac dysfunction. In the context of AHF, understanding the dual role of this pathway is crucial, as it functions both as a marker of compensatory adaptation and as a potential therapeutic target. Recent reviews and preclinical studies have linked PI3K/Akt activation with reduced myocardial apoptosis and attenuation of pro-inflammatory cascades that exacerbate heart failure. Among the multiple signaling pathways involved, glycogen synthase kinase-3β (GSK-3β) has emerged as a key regulator of apoptosis, inflammation, metabolic homeostasis, and cardiac remodeling. Recent studies underscore its dual function as both a negative regulator of pathological hypertrophy and a modulator of cell survival, making it a compelling therapeutic candidate in acute cardiac settings. While earlier investigations focused primarily on chronic heart failure and long-term remodeling, growing evidence now supports a critical role for GSK-3β dysregulation in acute myocardial stress and injury. This comprehensive review discusses recent advances in our understanding of the MAPK signaling pathway, the PI3K/Akt cascade, and GSK-3β activity in AHF, with a particular emphasis on mechanistic insights, preclinical models, and emerging therapeutic targets. Full article

Background: SARS-CoV-2 infection has been associated with long-term health consequences, including dysregulation of the renin–angiotensin–aldosterone system (RAAS). This study aimed to evaluate long-term changes in selected RAAS-related biochemical parameters in repeat convalescent plasma donors, focusing on enzymes and peptides involved in vascular regulation and inflammation. Methods: Thirty repeat convalescent plasma donors were enrolled, each providing four serum samples at defined time points post-infection. Samples were collected during Period 1 (≤60 days), Period 2 (61–90 days), Period 3 (91–120 days), and Period 4 (>120 days) after confirmed SARS-CoV-2 infection. The analyzed parameters included angiotensin I (Ang I), angiotensin II (Ang II), angiotensin 1–7 (Ang 1–7), angiotensin 1–9 (Ang 1–9), ACE, ACE2, ADAM10, and ADAM17. Concentrations were determined using ELISA assays. The control group consisted of pre-pandemic serum samples from healthy individuals. Results: An initial post-infection increase was observed in most parameters, particularly in Period 1. Over time, levels of several markers declined, yet Ang 1–7 and Ang 1–9 remained elevated compared to controls even beyond 120 days. Significant correlations (p < 0.05) were found between ADAM10, ADAM17, and angiotensin peptides, suggesting prolonged RAAS modulation. Metalloproteinases were notably elevated early after infection, potentially contributing to inflammatory and cardiovascular responses. Conclusions: The findings indicate a transient but measurable biochemical response of the RAAS following SARS-CoV-2 infection, with most parameters normalizing after 120 days. However, the sustained elevation of certain markers suggests a potential long-term impact on vascular homeostasis, warranting further investigation. Full article

Background/Objectives: The renin–angiotensin system (RAS) is well-established as a moderator of cardiovascular equilibrium and blood pressure. Nevertheless, growing evidence indicates that angiotensin II (Ang II), the principal RAS effector peptide, together with additional constituents, is involved in various malignancies. Since the immune system is an important aspect in tumor development, this study sought to investigate the role of Ang II in the crosstalk between tumor-associated macrophages (TAMs) and breast cancer cells in the tumor microenvironment (TME). Methods: We treated THP-1-like macrophages with 100 nM Ang II for 24 h. The culture media thus obtained was used as conditioned media and applied at 50% on MCF-7 and MDA-MB-231 breast cancer cell lines. The effects of the conditioned media on cancer cell lines were then investigated by various methods such as a cell proliferation assay, migration assay, polarization assay, and by the detection of apoptosis and reactive oxygen species (ROS) generation. Results: We demonstrated that in vitro Ang II promotes macrophage polarization toward proinflammatory M1-like macrophages and anti-inflammatory M2-like macrophages. Interestingly, Ang II, through macrophages, showed varied effects on different breast cancer cell lines, promoting tumor growth and progression in MCF-7 while inhibiting tumor growth and progression in MDA-MB-23. Conclusions: This study has provided clear evidence that Ang II in the TME modulates TAM polarization and secretions, leading to different effects based on the type of breast cancer. Full article

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

Background/Objectives: Ellagic acid (EA) is a polyphenol found in several fruits and vegetables, including pomegranate, nuts and berries. It exhibits significant health benefits, mainly cardio- and vaso-protective; indeed, EA protects the myocardium against infarction and inhibits cardiac fibrosis. These beneficial effects may be, at least in part, promoted by calcium release from and uptake by the sarcoplasmic reticulum, which are crucial events for cardiac relaxation and contraction. Regardless, the exact mechanism is currently unclear. Methods: A deeper investigation of the role of EA in cardiac contractility and the underlying mechanism has been carried out by using an ex vivo model of isolated and perfused rat heart. Results and Discussion: EA perfusion (100 nM–10 µM) did not influence the coronary flow (CF), suggesting the absence of a vasoactivity, but significantly increased contractility parameters (LVDP and dP/dt). Interestingly, a more marked effect of EA on LVDP and dP/dt values was observed when it was perfused in the presence of AngII. Cyclopiazonic acid (CA) and red ruthenium (RR), specific antagonists of SERCA and RyRs, respectively, were used to explore the contribution of EA when the intracellular calcium handling was altered. In the presence of CA, EA, perfused at increasing concentrations, showed a very modest positive inotropism (significant only at 1 µM). Instead, RR, which significantly compromised all functional parameters, completely masked the effects of EA; furthermore, a marked reduction in CF and a dramatic impact on the positive inotropism occurred. Conclusions: These results demonstrate the positive inotropism of EA on isolated and perfused hearts and suggest that the RyRs may be a main target through which EA plays its effects, since inhibition with RR almost completely blocks the positive inotropism. Full article