The renin-angiotensin system modulates inflammatory processes in atherosclerosis: evidence from basic research and clinical studies

New Insights into the French Paradox: Free Radical Scavenging by Resveratrol Yields Cardiovascular Protective Metabolites

Resveratrol was subjected to a diversity-oriented synthesis using oxidative transformations by various biorelevant, biomimetic, or biomimetic-related chemical reagents. Using a combined strategy of ultrahigh-resolution profiling, bioactivity screening, and bioactivity-guided isolation, 19 metabolites were obtained. The compounds were tested for their in vitro enzyme inhibitory activity on angiotensin-1 converting enzyme (ACE), cyclooxygenase-1 and -2, and 15-lipoxygenase (LOX), and evaluated for their relevant drug-like properties in silico. The compounds demonstrated a generally increased cardiovascular protective and anti-inflammatory potential and better drug-likeness compared to resveratrol. Trans-δ-viniferin (6) was identified as a competitive, C-domain-selective ACE inhibitor that is over 20 times more potent than resveratrol. Further, trans-ε-viniferin (2) acted as an over 40 times stronger LOX inhibitor than resveratrol. While our results cannot be directly translated to the health benefits of dietary resveratrol consumption without further studies, it is demonstrated that biologically relevant oxidative environments transform resveratrol into potent cardiovascular protective and anti-inflammatory metabolites.

Assessing the protective effects of nanoceria on angiotensin II-induced cardiac injury in H9c2 cardiomyoblasts using proteomic analysis

Oxidative stress and inflammation induced by angiotensin II (Ang II) stimulation have been identified to be major contributing factors in cardiovascular diseases. To mitigate these deleterious effects of Ang II, nanoceria have emerged as promising nanoparticles that can mimic natural antioxidants. Here, we aimed to demonstrate the protective effects of cerium oxide nanoparticles (CeO₂ or nanoceria) against Ang II stimulation and compared them to Ang II treatment alone using proteomic approach in H9c2 cardiomyoblasts. The differentially expressed protein profiles between different groups were visualized by 2D-DIGE analysis, and protein identitied were verified by MALDI-TOF mass spectrometry. PCA, hierarchical clustering and protein function analysis were conducted. Our findings indicated that 118 differentially expressed protein spots between the untreated control, Ang II treated, and nanoceria pretreated Ang II groups. Of these 76 protein sequences were identified by MALDI-TOF mass spectrometry. On comparing the untreated control samples to the Ang II-treated samples, 12 proteins were downregulated and 39 proteins were upregulated. In contrast, 18 proteins were downregulated and 35 proteins were upregulated in the nanoceria pretreated Ang II group compared to Ang II treatment alone. The proteins that were upregulated by Ang II treatment are associated with oxidative stress. In contrast, nanoceria pretreatment downregulated these proteins and also significantly upregulated the proteins linked to defense against oxidative damage. The biochemical pathways were identified by canonical pathway analysis. In conclusion, this work uncovers the complex proteomic changes in H9c2 cardiomyoblasts in response to Ang II and emphasizes the possible protective effects of nanoceria against Ang II-induced pathology.

Predicting early-stage coronary artery disease using machine learning and routine clinical biomarkers improved by augmented virtual data

Aims

Coronary artery disease (CAD) is a highly prevalent disease with modifiable risk factors. In patients with suspected obstructive CAD, evaluating the pre-test probability model is crucial for diagnosis, although its accuracy remains controversial. Machine learning (ML) predictive models can help clinicians detect CAD early and improve outcomes. This study aimed to identify early-stage CAD using ML in conjunction with a panel of clinical and laboratory tests.

Methods and results

The study sample included 3316 patients enrolled in the Ludwigshafen Risk and Cardiovascular Health (LURIC) study. A comprehensive array of attributes was considered, and an ML pipeline was developed. Subsequently, we utilized five approaches to generating high-quality virtual patient data to improve the performance of the artificial intelligence models. An extension study was carried out using data from the Young Finns Study (YFS) to assess the results' generalizability. Upon applying virtual augmented data, accuracy increased by approximately 5%, from 0.75 to -0.79 for random forests (RFs), and from 0.76 to -0.80 for Gradient Boosting (GB). Sensitivity showed a significant boost for RFs, rising by about 9.4% (0.81-0.89), while GB exhibited a 4.8% increase (0.83-0.87). Specificity showed a significant boost for RFs, rising by ∼24% (from 0.55 to 0.70), while GB exhibited a 37% increase (from 0.51 to 0.74). The extension analysis aligned with the initial study.

Conclusion

Accurate predictions of angiographic CAD can be obtained using a set of routine laboratory markers, age, sex, and smoking status, holding the potential to limit the need for invasive diagnostic techniques. The extension analysis in the YFS demonstrated the potential of these findings in a younger population, and it confirmed applicability to atherosclerotic vascular disease.

Aprotinin (I): Understanding the Role of Host Proteases in COVID-19 and the Importance of Pharmacologically Regulating Their Function

Proteases are produced and released in the mucosal cells of the respiratory tract and have important physiological functions, for example, maintaining airway humidification to allow proper gas exchange. The infectious mechanism of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), takes advantage of host proteases in two ways: to change the spatial conformation of the spike (S) protein via endoproteolysis (e.g., transmembrane serine protease type 2 (TMPRSS2)) and as a target to anchor to epithelial cells (e.g., angiotensin-converting enzyme 2 (ACE2)). This infectious process leads to an imbalance in the mucosa between the release and action of proteases versus regulation by anti-proteases, which contributes to the exacerbation of the inflammatory and prothrombotic response in COVID-19. In this article, we describe the most important proteases that are affected in COVID-19, and how their overactivation affects the three main physiological systems in which they participate: the complement system and the kinin-kallikrein system (KKS), which both form part of the contact system of innate immunity, and the renin-angiotensin-aldosterone system (RAAS). We aim to elucidate the pathophysiological bases of COVID-19 in the context of the imbalance between the action of proteases and anti-proteases to understand the mechanism of aprotinin action (a panprotease inhibitor). In a second-part review, titled "Aprotinin (II): Inhalational Administration for the Treatment of COVID-19 and Other Viral Conditions", we explain in depth the pharmacodynamics, pharmacokinetics, toxicity, and use of aprotinin as an antiviral drug.

Cardiac magnetic resonance imaging in systemic sclerosis: Heart involvement in high-resolution

Cardiac magnetic resonance imaging (CMR) is the gold-standard non-invasive method of assessing cardiac structure and function, including tissue characterisation. In systemic sclerosis (SSc), heart involvement (SHI) is a leading cause of mortality yet remains poorly understood. SHI is underestimated by conventional echocardiography, and CMR provides an important opportunity to better identify and quantify subtle myocardial changes including oedema and fibrosis. This review summarises current CMR techniques, the role of CMR in SSc and SHI, and the opportunities to further our understanding of its pathogenesis and management.

Sex Differences in Glomerular Lesions, in Atherosclerosis Progression, and in the Response to Angiotensin-Converting Enzyme Inhibitors in the ApoE-/- Mice Model

This study analyzes sex-based differences in renal structure and the response to the Angiotensin-Converting Enzyme (ACE) inhibitor enalapril in a mouse model of atherosclerosis. Eight weeks old ApoE-/- mice received enalapril (5 mg/kg/day, subcutaneous) or PBS (control) for an additional 14 weeks. Each group consisted of six males and six females. Females exhibited elevated LDL-cholesterol levels, while males presented higher creatinine levels and proteinuria. Enalapril effectively reduced blood pressure in both groups, but proteinuria decreased significantly only in females. Plaque size analysis and assessment of kidney inflammation revealed no significant sex-based differences. However, males displayed more severe glomerular injury, with increased mesangial expansion, mesangiolysis, glomerular foam cells, and activated parietal epithelial cells (PECs). Enalapril mitigated mesangial expansion, glomerular inflammation (particularly in the female group), and hypertrophy of the PECs in males. This study demonstrates sex-based differences in the response to enalapril in a mouse model of atherosclerosis. Males exhibited more severe glomerular injury, while enalapril provided renal protection, particularly in females. These findings suggest potential sex-specific considerations for ACE inhibitor therapy in chronic kidney disease and atherosclerosis cardiovascular disease. Further research is needed to elucidate the underlying mechanism behind these observations.

Vanillin and pentoxifylline ameliorate isoproterenol-induced myocardial injury in rats via the Akt/HIF-1α/VEGF signaling pathway

Myocardial infarction (MI) is a major health problem associated with high morbidity and mortality. Recently, angiogenesis has emerged as a novel therapeutic approach against ischemic diseases including MI. Therefore, we aimed to investigate the potential angiogenic effects of vanillin (Van) both alone and in combination with pentoxifylline (PTX), and to examine the molecular mechanisms through which Van and PTX may ameliorate cardiac injury induced in rats including their effects on oxidative stress, inflammation and apoptosis which play a key role in MI pathogenesis. MI was induced in rats using isoproterenol (ISO) (150 mg kg^-1, SC, twice at a 24 h interval). Then, rats were treated orally with Van (150 mg kg^-1 day^-1), PTX (50 mg kg^-1 day^-1) or Van + PTX combination. ISO-induced cardiac injury was characterized by cardiac hypertrophy, ST-segment elevation and elevated serum levels of troponin-I, creatine kinase-MB and lactate dehydrogenase. Cardiac levels of the antioxidant markers GSH and SOD and the antiapoptotic protein Bcl-2 were decreased. On the other hand, cardiac levels of the oxidative stress marker malonaldehyde, the inflammatory cytokines TNF-α, IL-6 and IL-1β, the proapoptotic protein Bax, and caspase-3 were increased. Moreover, the cardiac levels of p-Akt and HIF-1α and the mRNA expression levels of the angiogenic genes VEGF, FGF-2 and ANGPT-1 were increased. Treatment with either Van or PTX ameliorated ISO-induced changes and further upregulated Akt/HIF-1α/VEGF signaling. Furthermore, Van + PTX combination was more effective than monotherapy. These findings suggest a novel therapeutic potential of Van and PTX in ameliorating MI through enhancing cardiac angiogenesis and modulating oxidative stress, inflammation and apoptosis.

Cardiac inflammation and fibrosis patterns in systemic sclerosis, evaluated by magnetic resonance imaging: An update

Systemic sclerosis (SSc) presents high morbidity/mortality, due to internal organ fibrosis, including the heart. Cardiac magnetic resonance (CMR) can perform myocardial function and tissue characterization in the same examination. The Lake Louise criteria (LLC) can identify recent myocardial inflammation using CMR. Abnormal values include: (a) myocardial over skeletal muscle ratio in STIRT2-W images >2, (b) early gadolinium enhancement values >4, (c) epicardial/intramyocardial late gadolinium enhancement (LGE). The diagnosis of myocarditis using LLC is considered if 2/3 criteria are positive. Parametric imaging including T2, native T1 mapping and extracellular volume fraction (ECV) has been recently used to diagnose inflammatory cardiomyopathy. According to expert recommendations, myocarditis should be considered if at least 2 indices, one T2 and one T1 parameter are positive, whereas native T1 mapping and ECV assess diffuse fibrosis or oedema, even in the absence of LGE. Moreover, transmural/subendocardial fibrosis following the distribution of coronary arteries and diffuse subendocardial fibrosis not related with epicardial coronary arteries are indicative of epicardial and micro-vascular coronary artery disease, respectively. To conclude, CMR can identify acute/active myocardial inflammation and myocardial infarction using classic and parametric indices in parallel with ventricular function evaluation.

Inflammaging and Blood Pressure Profiles in Late Life: The Screening for CKD among Older People across Europe (SCOPE) Study

The neutrophil-to-lymphocyte ratio (NLR) is a marker for systemic inflammation. Since inflammation plays a relevant role in vascular aging, the aim of this study was to investigate whether NLR is associated with blood pressure profiles in older adults. This study was performed within the framework of the SCOPE study including 2461 outpatients aged 75 years and over. Mean blood pressure values, namely systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure (PP) were investigated across tertiles of NLR. Change in blood pressure levels in 2 years of follow-up were compared across categories of baseline NLR. Data of 2397 individuals were used, of which 1854 individuals had hypertension. Mean values of blood pressure did not differ across categories of baseline NLR in individuals without hypertension. Individuals with hypertension with a high-range NLR had lower SBP and PP when compared to those in low-range NLR (mean difference SBP -2.94 mmHg, p = 0.032 and PP -2.55 mmHg, p = 0.030). Mean change in blood pressure in 2 years did only slightly differ in non-clinically relevant ranges, when compared across tertiles of baseline NLR. NLR as a marker of inflammaging was not associated with unfavorable blood pressure profiles in older individuals with or without hypertension.

Role of renin-angiotensin-aldosterone system activation and other metabolic variables in relation to arterial inflammation in HIV

BACKGROUND

Arterial inflammation remains increased among persons with HIV (PWH) compared with persons without HIV (PWOH) even when controlling for traditional risk factors. We sought to understand whether increased renin-angiotensin-aldosterone system (RAAS) activation may be related to arterial inflammation in PWH and when compared with PWOH.

DESIGN

Twenty PWH and 9 PWOH followed a controlled, standardized low and liberal sodium diet to simulate a RAAS-activated and RAAS-suppressed state, respectively. We measured serum lipoprotein-associated phospholipase A2 (LpPLA2) concentrations following both conditions to assess the physiologic dynamics of aldosterone in relation to arterial inflammation.

RESULTS

LpPLA2 levels were significantly higher among PWH versus PWOH during both the RAAS-activated state[5.3(4.2, 6.1) versus 4.0(3.0, 4.8)nmol/L, median(interquartile range),p = .01]) and RAAS-suppressed state[4.4(3.9, 5.3) versus 3.8(3.4, 4.1)nmol/L,p = .01]. Among PWH, but not PWOH, LpPLA2 increased significantly with RAAS activation(p = .03). LpPLA2 levels measured during the RAAS-suppressed state among PWH remained relatively higher than LpPLA2 levels under both conditions among PWOH. Log LpPLA2 was related to log aldosterone during the RAAS-activated state(r = .39,p = .04) among all participants. Log LpPLA2 was correlated with visceral fat(r = .46,p = .04) and log systolic blood pressure(r = .57,p = .009) during a RAAS-activated state when an increase in aldosterone was stimulated in HIV.

CONCLUSION

LpPLA2 is increased during a RAAS-activated state among PWH, but not among PWOH. Further, LpPLA2 was increased in both RAAS-activated and suppressed states in PWH compared with PWOH. These data suggest a biological link between increased aldosterone and arterial inflammation in this population. Future studies should test RAAS blockade on arterial inflammation as a targeted treatment approach in HIV.

Effect of the Renin-Angiotensin System Inhibitors on Inflammatory Markers: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

To synthesize more conclusive evidence on the anti-inflammatory effects of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs).

METHODS

PubMed, Scopus, and Embase were searched from inception until March 1, 2021. We included randomized controlled trials (RCTs) that assessed the effect of ACEIs or ARBs, compared with placebo, on any of the following markers: C-reactive protein (CRP), interleukin 6 (IL-6), or tumor necrosis factor α (TNF-α). Mean changes in the levels of these markers were pooled as a weighted mean difference (WMD) with a 95% CI.

RESULTS

Thirty-two RCTs (n=3489 patients) were included in the final analysis. Overall pooled analysis suggested that ACEIs significantly reduced plasma levels of CRP (WMD, -0.54 [95% CI, -0.88 to -0.21]; P=.002; I²=96%), IL-6 (WMD, -0.84 [95% CI, -1.03 to -0.64]; P<.001; I²=0%), and TNF-α (WMD, -12.75 [95% CI, -17.20 to -8.29]; P<.001; I²=99%). Moreover, ARBs showed a significant reduction only in IL-6 (WMD, -1.34 [95% CI, -2.65 to -0.04]; P=.04; I²=85%) and did not significantly affect CRP (P=.15) or TNF-α (P=.97) levels. The lowering effect of ACEIs on CRP levels remained significant with enalapril (P=.006) and perindopril (P=.01) as well as with a treatment duration of less than 24 weeks (WMD, -0.67 [95% CI, -1.07 to -0.27]; P=.001; I²=94%) and in patients with coronary artery disease (WMD, -0.75 [95% CI, -1.17 to -0.33]; P<.001; I²=96%).

CONCLUSION

Based on this meta-analysis, ACEIs showed a beneficial lowering effect on CRP, IL-6, and TNF-α, whereas ARBs were effective as a class in reduction of IL-6 only.

Role of the renin-angiotensin system in the development of COVID-19-associated neurological manifestations

SARS-CoV-2 causes COVID-19, which has claimed millions of lives. This virus can infect various cells and tissues, including the brain, for which numerous neurological symptoms have been reported, ranging from mild and non-life-threatening (e.g., headaches, anosmia, dysgeusia, and disorientation) to severe and life-threatening symptoms (e.g., meningitis, ischemic stroke, and cerebral thrombosis). The cellular receptor for SARS-CoV-2 is angiotensin-converting enzyme 2 (ACE2), an enzyme that belongs to the renin-angiotensin system (RAS). RAS is an endocrine system that has been classically associated with regulating blood pressure and fluid and electrolyte balance; however, it is also involved in promoting inflammation, proliferation, fibrogenesis, and lipogenesis. Two pathways constitute the RAS with counter-balancing effects, which is the key to its regulation. The first axis (classical) is composed of angiotensin-converting enzyme (ACE), angiotensin (Ang) II, and angiotensin type 1 receptor (AT1R) as the main effector, which -when activated- increases the production of aldosterone and antidiuretic hormone, sympathetic nervous system tone, blood pressure, vasoconstriction, fibrosis, inflammation, and reactive oxygen species (ROS) production. Both systemic and local classical RAS' within the brain are associated with cognitive impairment, cell death, and inflammation. The second axis (non-classical or alternative) includes ACE2, which converts Ang II to Ang-(1-7), a peptide molecule that activates Mas receptor (MasR) in charge of opposing Ang II/AT1R actions. Thus, the alternative RAS axis enhances cognition, synaptic remodeling, cell survival, cell signal transmission, and antioxidant/anti-inflammatory mechanisms in the brain. In a physiological state, both RAS axes remain balanced. However, some factors can dysregulate systemic and local RAS arms. The binding of SARS-CoV-2 to ACE2 causes the internalization and degradation of this enzyme, reducing its activity, and disrupting the balance of systemic and local RAS, which partially explain the appearance of some of the neurological symptoms associated with COVID-19. Therefore, this review aims to analyze the role of RAS in the development of the neurological effects due to SARS-CoV-2 infection. Moreover, we will discuss the RAS-molecular targets that could be used for therapeutic purposes to treat the short and long-term neurological COVID-19-related sequelae.

Angiotensin II Type I Receptor (AT1R): The Gate towards COVID-19-Associated Diseases

The binding of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike glycoprotein to its cellular receptor, the angiotensin-converting enzyme 2 (ACE2), causes its downregulation, which subsequently leads to the dysregulation of the renin-angiotensin system (RAS) in favor of the ACE-angiotensin II (Ang II)-angiotensin II type I receptor (AT1R) axis. AT1R has a major role in RAS by being involved in several physiological events including blood pressure control and electrolyte balance. Following SARS-CoV-2 infection, pathogenic episodes generated by the vasoconstriction, proinflammatory, profibrotic, and prooxidative consequences of the Ang II-AT1R axis activation are accompanied by a hyperinflammatory state (cytokine storm) and an acute respiratory distress syndrome (ARDS). AT1R, a member of the G protein-coupled receptor (GPCR) family, modulates Ang II deleterious effects through the activation of multiple downstream signaling pathways, among which are MAP kinases (ERK 1/2, JNK, p38MAPK), receptor tyrosine kinases (PDGF, EGFR, insulin receptor), and nonreceptor tyrosine kinases (Src, JAK/STAT, focal adhesion kinase (FAK)), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. COVID-19 is well known for generating respiratory symptoms, but because ACE2 is expressed in various body tissues, several extrapulmonary pathologies are also manifested, including neurologic disorders, vasculature and myocardial complications, kidney injury, gastrointestinal symptoms, hepatic injury, hyperglycemia, and dermatologic complications. Therefore, the development of drugs based on RAS blockers, such as angiotensin II receptor blockers (ARBs), that inhibit the damaging axis of the RAS cascade may become one of the most promising approaches for the treatment of COVID-19 in the near future. We herein review the general features of AT1R, with a special focus on the receptor-mediated activation of the different downstream signaling pathways leading to specific cellular responses. In addition, we provide the latest insights into the roles of AT1R in COVID-19 outcomes in different systems of the human body, as well as the role of ARBs as tentative pharmacological agents to treat COVID-19.

Role of inflammation in benign gynecologic disorders: from pathogenesis to novel therapies†

Emerging evidence supports the notion that inflammation fosters the development of common benign gynecologic disorders, including uterine leiomyoma, endometriosis, and adenomyosis. Numerous cytokines, chemokines, and growth and transcription factors have indisputable roles in the establishment and maintenance of benign gynecologic disorders by initiating complex cascades that promote proliferation, angiogenesis, and lesion progression. The interaction between inflammation and benign gynecologic disorders is orchestrated by a plethora of factors, including sex steroids, genetics, epigenetics, extracellular matrix, stem cells, cardiometabolic risk factors, diet, vitamin D, and the immune system. The role of inflammation in these disorders is not limited to local pathobiology but also extends to involve clinical sequelae that range from those confined to the reproductive tract, such as infertility and gynecologic malignancies, to systemic complications such as cardiovascular disease. Enhanced understanding of the intricate mechanisms of this association will introduce us to unvisited pathophysiological perspectives and guide future diagnostic and therapeutic implications aimed at reducing the burden of these disorders. Utilization of inflammatory markers, microRNA, and molecular imaging as diagnostic adjuncts may be valuable, noninvasive techniques for prompt detection of benign gynecologic disorders. Further, use of novel as well as previously established therapeutics, such as immunomodulators, hormonal treatments, cardiometabolic medications, and cyclooxygenase-2 and NF-κB inhibitors, can target inflammatory pathways involved in their pathogenesis. In this comprehensive review, we aim to dissect the existing literature on the role of inflammation in benign gynecologic disorders, including the proposed underlying mechanisms and complex interactions, its contribution to clinical sequelae, and the clinical implications this role entails.

Common genetic variants and pathways in diabetes and associated complications and vulnerability of populations with different ethnic origins

Diabetes mellitus is a complex and heterogeneous metabolic disorder which is often pre- or post-existent with complications such as cardiovascular disease, hypertension, inflammation, chronic kidney disease, diabetic retino- and nephropathies. However, the frequencies of these co-morbidities vary among individuals and across populations. It is, therefore, not unlikely that certain genetic variants might commonly contribute to these conditions. Here, we identified four single nucleotide polymorphisms (rs5186, rs1800795, rs1799983 and rs1800629 in AGTR1, IL6, NOS3 and TNFA genes, respectively) to be commonly associated with each of these conditions. We explored their possible interplay in diabetes and associated complications. The variant allele and haplotype frequencies at these polymorphic loci vary among different super-populations (African, European, admixed Americans, South and East Asians). The variant alleles are particularly highly prevalent in different European and admixed American populations. Differential distribution of these variants in different ethnic groups suggests that certain drugs might be more effective in selective populations rather than all. Therefore, population specific genetic architectures should be considered before considering a drug for these conditions.

Renin-Angiotensin System in Lung Tumor and Microenvironment Interactions

The mechanistic involvement of the renin-angiotensin system (RAS) reaches beyond cardiovascular physiopathology. Recent knowledge pinpoints a pleiotropic role for this system, particularly in the lung, and mainly through locally regulated alternative molecules and secondary pathways. Angiotensin peptides play a role in cell proliferation, immunoinflammatory response, hypoxia and angiogenesis, which are critical biological processes in lung cancer. This manuscript reviews the literature supporting a role for the renin-angiotensin system in the lung tumor microenvironment and discusses whether blockade of this pathway in clinical settings may serve as an adjuvant therapy in lung cancer.

A Role of Inflammation and Immunity in Essential Hypertension-Modeled and Analyzed Using Petri Nets

Recent studies have shown that the innate and adaptive immune system, together with low-grade inflammation, may play an important role in essential hypertension. In this work, to verify the importance of selected factors for the development of essential hypertension, we created a Petri net-based model and analyzed it. The analysis was based mainly on t-invariants, knockouts of selected fragments of the net and its simulations. The blockade of the renin-angiotensin (RAA) system revealed that the most significant effect on the emergence of essential hypertension has RAA activation. This blockade affects: (1) the formation of angiotensin II, (2) inflammatory process (by influencing C-reactive protein (CRP)), (3) the initiation of blood coagulation, (4) bradykinin generation via the kallikrein-kinin system, (5) activation of lymphocytes in hypertension, (6) the participation of TNF alpha in the activation of the acute phase response, and (7) activation of NADPH oxidase-a key enzyme of oxidative stress. On the other hand, we found that the blockade of the activation of the RAA system may not eliminate hypertension that can occur due to disturbances associated with the osmotically independent binding of Na in the interstitium. Moreover, we revealed that inflammation alone is not enough to trigger primary hypertension, but it can coexist with it. We believe that our research may contribute to a better understanding of the pathology of hypertension. It can help identify potential subprocesses, which blocking will allow better control of essential hypertension.

The immunopathogenesis of tuberculous pericarditis

Tuberculous pericarditis is a severe form of extrapulmonary tuberculosis and is the commonest cause of pericardial effusion in high incidence settings. Mortality ranges between 8 and 34%, and it is the leading cause of pericardial constriction in Africa and Asia. Current understanding of the disease is based on models derived from studies performed in the 1940-50s. This review summarises recent advances in the histology, microbiology and immunology of tuberculous pericarditis, with special focus on the effect of Human Immunodeficiency Virus (HIV) and the determinants of constriction.

Overexpression of ACE in Myeloid Cells Increases Immune Effectiveness and Leads to a New Way of Considering Inflammation in Acute and Chronic Diseases

PURPOSE OF REVIEW

To review recent studies exploring how myeloid cell overexpression of angiotensin-converting enzyme (ACE) affects the immune response and to formulate an approach for considering the effectiveness of inflammation in cardiovascular disease RECENT FINDINGS: While it is widely appreciated that the renin-angiotensin system affects aspects of inflammation through the action of angiotensin II, new studies reveal a previously unknown role of ACE in myeloid cell biology. This was apparent from analysis of two mouse lines genetically modified to overexpress ACE in monocytes/macrophages or neutrophils. Cells overexpressing ACE demonstrated an increased immune response. For example, mice with increased macrophage ACE expression have increased resistance to melanoma, methicillin-resistant Staphylococcus aureus, a mouse model of Alzheimer's disease, and ApoE-knockout-induced atherosclerosis. These data indicate the profound effect of increasing myeloid cell function. Further, they suggest that an appropriate way to evaluate inflammation in both acute and chronic diseases is to ask whether the inflammatory infiltrate is sufficient to eliminate the immune challenge. The expression of ACE by myeloid cells induces a heightened immune response by these cells. The overexpression of ACE is associated with immune function beyond that possible by wild type (WT) myeloid cells. A heightened immune response effectively resolves disease in a variety of acute and chronic models of disease including models of Alzheimer's disease and atherosclerosis.

Soluble RAGEs and cardiovascular risk factors in adult offspring of patients with premature coronary heart disease

Purpose: Advanced glycation end products (AGEs) are a heterogeneous group of highly oxidant compounds which can potentiate microvascular and macrovascular complications through the formation of irreversible cross-links between molecules in the basal membrane and also by engaging the receptor for AGEs (RAGE). Soluble receptor for AGEs (sRAGE) is suggested to have a protective role neutralizing the toxic action of AGEs. We aimed to investigate differences in plasma levels of sRAGE alongside with classic cardiovascular risk factors between offspring of patients with early onset of coronary heart disease (CHD) and healthy controls.Materials and methods: In a cross-sectional design, we examined 114 adult offspring of patients with premature CHD and 194 controls. Concentrations of soluble RAGE were quantified by ELISA methods. Aortic PWV was measured using Sphygmocor device. Multivariate logistic regressions were used to compare differences between the offspring and controls.Results: In the offspring group there were more men (p = 0.023), both groups had similar age (28.5 vs. 28.9 years; p = 0.51). After adjustment for covariates, we observed significantly higher aPWV (6.17 vs. 5.82 m s^-1; p = 0.001) and lower sRAGE (1308.11 vs. 1475.59; p = 0.009) in the offspring group compared to controls. The significant determinants of the intergroup difference were sRAGE (p = 0.0017), aPWV (p = 0.011) and current smoking (p = 0.0053).Conclusion: Offspring of patients with early onset of CHD compared to age-matched healthy controls had significantly lower sRAGE levels suggesting a shift in the oxidative balance between stressors and defence mechanisms that may influence a higher cardiovascular risk in the future. The measurement of sRAGE might be a valuable predictor for more precise stratification of cardiovascular risk.

[The renin-angiotensin-aldosterone system as a potential target for therapy in patients with calcific aortic stenosis: a literature review]

Calcific aortic valve stenosis (CAVS) is a serious socio-economic problem in developed countries because this disease is the most common indication for aortic valve replacement. Currently, there are no methods for non-invasive treatment of CAVS. Nevertheless, it is assumed that effective drug therapy for CAVS can be developed on the basis of modulators of the renin-angiotensin-aldosterone system (RAAS), which is involved in the pathogenesis of this disease. The purpose of this paper is to compile and analyze current information on the role of RAAS in the CAVS pathophysiology. Recent data on the effectiveness of RAAS inhibition are reviewed.

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

The renin-angiotensin-aldosterone system plays crucial roles in cardiovascular physiology and pathophysiology. However, many of the signaling mechanisms have been unclear. The angiotensin II (ANG II) type 1 receptor (AT₁R) is believed to mediate most functions of ANG II in the system. AT₁R utilizes various signal transduction cascades causing hypertension, cardiovascular remodeling, and end organ damage. Moreover, functional cross-talk between AT₁R signaling pathways and other signaling pathways have been recognized. Accumulating evidence reveals the complexity of ANG II signal transduction in pathophysiology of the vasculature, heart, kidney, and brain, as well as several pathophysiological features, including inflammation, metabolic dysfunction, and aging. In this review, we provide a comprehensive update of the ANG II receptor signaling events and their functional significances for potential translation into therapeutic strategies. AT₁R remains central to the system in mediating physiological and pathophysiological functions of ANG II, and participation of specific signaling pathways becomes much clearer. There are still certain limitations and many controversies, and several noteworthy new concepts require further support. However, it is expected that rigorous translational research of the ANG II signaling pathways including those in large animals and humans will contribute to establishing effective new therapies against various diseases.

The potential therapeutic use of renin-angiotensin system inhibitors in the treatment of inflammatory diseases

Inflammation is a normal part of the immune response to injury or infection but its dysregulation promotes the development of inflammatory diseases, which cause considerable human suffering. Nonsteroidal anti-inflammatory agents are the most commonly prescribed agents for the treatment of inflammatory diseases, but they are accompanied by a broad range of side effects, including gastrointestinal and cardiovascular events. The renin-angiotensin system (RAS) is traditionally known for its role in blood pressure regulation. However, there is increasing evidence that RAS signaling is also involved in the inflammatory response associated with several disease states. Angiotensin II increases blood pressure by binding to angiotensin type 1 (AT₁ ) receptor, and direct renin inhibitors, angiotensin-converting enzyme (ACE) inhibitors and AT₁ receptor blockers (ARBs) are clinically used as antihypertensive agents. Recent data suggest that these drugs also have anti-inflammatory effects. Therefore, this review summarizes these recent findings for the efficacy of two of the most widely used antihypertensive drug classes, ACE inhibitors and ARBs, to reduce or treat inflammatory diseases such as atherosclerosis, arthritis, steatohepatitis, colitis, pancreatitis, and nephritis.

Protective Effect of Polyphenol-Rich Extract from Bee Pollen in a High-Fat Diet

We have studied a preventive effect of polyphenol-rich bee pollen ethanol extract (EEP) against histological changes in the liver and cardiac blood vessels, abnormalities of lipid profile, and the levels of oxidized low density lipoproteins (ox-LDL), asymmetric dimethylarginine (ADMA), angiotensin-converting enzyme (ACE), and angiotensin II (ANG II) caused by a high-fat diet in C₅₇BL₆ mice. Supplementing the diet with EEP in the doses of 0.1 g/kg body mass (BM) and 1 g/kg BM resulted in a decrease of total cholesterol by 31% and 35%, respectively. It also decreased the level of low density lipoproteins by 67% and 90%, respectively. No differences in the levels of high density lipoprotein and triacylglycerols were observed. EEP reduced the level of ox-LDL by 33% and 47%, ADMA by 13% and 51%, ACE by 17% and 30%, as well as ANG II by 11% and 15% in a dose-dependent manner, which proves a protective effect of EEP in a high-fat diet. EEP reduces and/or prevents hepatic steatosis and degenerative changes caused by a high-fat diet in C₅₇BL₆ mice, which indicates its hepatoprotective effect. EEP used with standard feed does not disturb a normal concentration of the assayed parameters.

Cancer Stem Cells in Moderately Differentiated Lip Squamous Cell Carcinoma Express Components of the Renin-Angiotensin System

Aim

We investigated the expression of the renin–angiotensin system (RAS) by cancer stem cell (CSC) subpopulations we have identified in moderately differentiated lip squamous cell carcinoma (MDLSCC).

Method

Ten MDLSCC samples underwent 3,3-diaminobenzidine (DAB) and immunofluorescent immunohistochemical (IHC) staining for (pro)renin receptor (PRR), angiotensin-converting enzyme (ACE), angiotensin II receptor 1 (ATIIR1), and receptor 2 (ATIIR2). NanoString analysis and Western blotting (WB) were performed on six MDLSCC samples for gene and protein expression, respectively.

Results

IHC staining showed expression of PRR, ATIIR1, and ATIIR2 on cells within the tumor nests (TNs) and the stroma. ACE was localized to the microvessels within the stroma. WB detected PRR, ACE, and ATIIR2. NanoString analysis confirmed gene expression of PRR, ACE, and ATIIR1.

Conclusion

Components of the RAS: PRR, ATIIR1, and ATIIR2 are expressed on two CSC subpopulations in MDLSCC, one within the TNs and the other within the stroma. The endothelium of the microvessels within the stroma expresses ACE.

Methotrexate carried in lipid core nanoparticles reduces myocardial infarction size and improves cardiac function in rats

Purpose

Acute myocardial infarction (MI) is accompanied by myocardial inflammation, fibrosis, and ventricular remodeling that, when excessive or not properly regulated, may lead to heart failure. Previously, lipid core nanoparticles (LDE) used as carriers of the anti-inflammatory drug methotrexate (MTX) produced an 80-fold increase in the cell uptake of MTX. LDE-MTX treatment reduced vessel inflammation and atheromatous lesions induced in rabbits by cholesterol feeding. The aim of the study was to investigate the effects of LDE-MTX on rats with MI, compared with commercial MTX treatment.

Materials and methods

Thirty-eight Wistar rats underwent left coronary artery ligation and were treated with LDE-MTX, or with MTX (1 mg/kg intraperitoneally, once/week, starting 24 hours after surgery) or with LDE without drug (MI-controls). A sham-surgery group (n=12) was also included. Echocardiography was performed 24 hours and 6 weeks after surgery. The animals were euthanized and their hearts were analyzed for morphometry, protein expression, and confocal microscopy.

Results

LDE-MTX treatment achieved a 40% improvement in left ventricular (LV) systolic function and reduced cardiac dilation and LV mass, as shown by echocardiography. LDE-MTX reduced the infarction size, myocyte hypertrophy and necrosis, number of inflammatory cells, and myocardial fibrosis, as shown by morphometric analysis. LDE-MTX increased antioxidant enzymes; decreased apoptosis, macrophages, reactive oxygen species production; and tissue hypoxia in non-infarcted myocardium. LDE-MTX increased adenosine bioavailability in the LV by increasing adenosine receptors and modulating adenosine catabolic enzymes. LDE-MTX increased the expression of myocardial vascular endothelium growth factor (VEGF) associated with adenosine release; this correlated not only with an increase in angiogenesis, but also with other parameters improved by LDE-MTX, suggesting that VEGF increase played an important role in the beneficial effects of LDE-MTX. Overall effects of commercial MTX were minor, and did not improve LV function or infarction size. Both treatments did not induce any toxicity.

Conclusion

The remarkable improvement in heart function and reduction in infarction size achieved by LDE-MTX supports future clinical trials.

The angiotensin-converting enzyme inhibitor captopril rescues mice from endotoxin-induced lethal hepatitis

The renin–angiotensin system is classically regarded as a crucial regulator of circulatory homeostasis, but recent studies also revealed its pro-inflammatory roles. The beneficial effects of the angiotensin-converting enzyme inhibitor (ACEI) in severe inflammatory injury in the lung and heart have been previously reported, but its potential effects on lethal hepatitis were unknown. In this study, a mouse model with LPS/d-galactosamine (GalN)-induced fulminant hepatitis were used to test the protective potential of captopril, a representative ACEI. The results indicated that treatment with captopril significantly decreased the plasma level of alanine aminotransferase and aspartate aminotransferase, alleviated the histopathological damage of the liver tissue and improve the survival rate of LPS/GalN-challenged mice. These effects were accompanied by reduced mRNA levels of TNF-α and IL-6 in the liver, and decreased protein level of TNF-α and IL-6 in the plasma. In addition, the activation of caspases 3, 8 and 9, and the presence of TUNEL-positive apoptotic cells, were also suppressed by captopril treatment. The above evidence suggested that the renin–angiotensin system might be involved in the development of LPS/GalN-induced fulminant hepatitis and ACEI might have potential value in lethal hepatitis.

Prognostic Impact of Renin-Angiotensin Inhibitors in Patients with Bladder Cancer Undergoing Radical Cystectomy

BACKGROUND

Renin-angiotensin system blockade has been effective for the treatment of patients with several types of malignancy. This study evaluated the prognostic impact of renin-angiotensin system inhibitors, including angiotensin-2 converting enzyme inhibitors and angiotensin 2 receptor blockers, in patients with bladder cancer undergoing radical cystectomy.

METHODS

This retrospective study included 269 patients who had undergone radical cystectomy. The oncologic outcomes of patients treated or not treated with renin-angiotensin system inhibitors after surgery were evaluated. Overall survival and cancer-specific survival were assessed by the Kaplan-Meier method and by Cox regression analysis.

RESULTS

The median follow-up duration after radical cystectomy in survivors was 44.5 months. The 5-year, cancer-specific survival rates in patients who did and did not receive renin-angiotensin system inhibitors were 79.0 and 66.4 %, respectively (P = 0.011). Similarly, the 5-year overall survival rates were 76.1 and 61.4 %, respectively (P = 0.0097). Multivariable analyses showed that use of renin-angiotensin system inhibitors was an independent prognostic factor for cancer-specific survival (hazard ratio 0.47, P = 0.036) and for overall survival (hazard ratio 0.36, P = 0.022).

CONCLUSIONS

Renin-angiotensin system inhibitors significantly reduced the risks of cancer-specific and overall mortality after radical cystectomy in patients with bladder cancer. Renin-angiotensin system inhibitors may improve oncologic outcomes in high-risk patients with bladder cancer.

Inhibition of Angiotensin Converting Enzyme, Angiotensin II Receptor Blocking, and Blood Pressure Lowering Bioactivity across Plant Families

Hypertension is a major risk factor for coronary heart disease, kidney disease, and stroke. Interest in medicinal or nutraceutical plant bioactives to reduce hypertension has increased dramatically. The main biological regulation of mammalian blood pressure is via the renin-angiotensin-aldosterone system. The key enzyme is angiotensin converting enzyme (ACE) that converts angiotensin I into the powerful vasoconstrictor, angiotensin II. Angiotensin II binds to its receptors (AT1) on smooth muscle cells of the arteriole vasculature causing vasoconstriction and elevation of blood pressure. This review focuses on the in vitro and in vivo reports of plant-derived extracts that inhibit ACE activity, block angiotensin II receptor binding and demonstrate hypotensive activity in animal or human studies. We describe 74 families of plants that exhibited significant ACE inhibitory activity and 16 plant families with potential AT1 receptor blocking activity, according to in vitro studies. From 43 plant families including some of those with in vitro bioactivity, the extracts from 73 plant species lowered blood pressure in various normotensive or hypertensive in vivo models by the oral route. Of these, 19 species from 15 families lowered human BP when administered orally. Some of the active plant extracts, isolated bioactives and BP-lowering mechanisms are discussed.

Vascular endothelium - Gatekeeper of vessel health

The vascular endothelium is an interface between the blood stream and the vessel wall. Changes in this single cell layer of the artery wall are believed of primary importance in the pathogenesis of vascular disease/atherosclerosis. The endothelium responds to humoral, neural and especially hemodynamic stimuli and regulates platelet function, inflammatory responses, vascular smooth muscle cell growth and migration, in addition to modulating vascular tone by synthesizing and releasing vasoactive substances. Compromised endothelial function contributes to the pathogenesis of cardiovascular disease; endothelial 'dysfunction' is associated with risk factors, correlates with disease progression, and predicts cardiovascular events. Therapies for atherosclerosis have been developed, therefore, that are directed towards improving endothelial function.

Involvement of Angiotensin II Type 1 and 2 Receptors in Gelatinase Regulation in Human Carotid Atheroma in vitro

AIM

Matrix metalloproteinases (MMPs), angiotensin II (AII) and its receptors are implicated in atherosclerotic plaque instability, however the roles of the two receptor subtypes, ATR1 and ATR2, in MMP regulation remain uncertain. In this study, we investigated the effect of ATR1 and ATR2 blockade on the expression and activity of MMP-2, MMP-3 and MMP-9, in human carotid atheroma.

METHODS

Atheroma samples (n=36) were obtained from patients undergoing carotid endarterectomy. The effects of ATR1 (irbesartan), ATR2 (PD123319) and combined ATR1 and ATR2 blockade on the expression and activity of the MMPs and the expression of tissue inhibitors of metalloproteinases (TIMPs) were investigated in explant culture experiments. Paired atheroma samples were incubated with the intervention or media control for 4 days. Protein levels (MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2, TIMP-4, ATR1 and ATR2) were determined by ELISA. Overall gelatinase activity and specific activation were measured by chromogenic activity assays and zymography, respectively.

RESULTS

ATR1 blockade, but not ATR2 blockade significantly reduced TIMP-1, TIMP-2 and TIMP-4 expression in atheroma supernatant. Combined ATR1 and ATR2 blockade significantly reduced MMP-2, MMP-3 and MMP-9 expression. MMP-2 and MMP-9 relative activation, and overall MMP-9 catalytic capacity were significantly increased by ATR1 blockade.

CONCLUSIONS

Our findings suggest that ATR1 blockade reduces TIMP expression and increases gelatinase activity in human carotid atheroma.

Irbesartan attenuates atherosclerosis in Watanabe heritable hyperlipidemic rabbits: noninvasive imaging of inflammation by 18F-fluorodeoxyglucose positron emission tomography

The purpose of this study was to assess the usefulness of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in evaluating the antiatherogenic effects of irbesartan, an angiotensin II type 1 receptor blocker. Watanabe heritable hyperlipidemic rabbits were divided into the irbesartan-treated group (75 mg/kg/d; n  =  14) and the control group (n  =  14). After a 9-month treatment, rabbits underwent 18F-FDG PET. Using the aortic lesions, autoradiography and histologic examinations were performed. PET imaging clearly visualized the thoracic lesions of control rabbits and showed a significant decrease in the 18F-FDG uptake level of irbesartan-treated rabbits (78.8% of controls; p < .05). Irbesartan treatment significantly reduced the plaque size (43.1% of controls) and intraplaque macrophage infiltration level (48.1% of controls). The 18F-FDG uptake level in plaques positively correlated with the plaque size (r  =  .65, p < .05) and macrophage infiltration level (r  =  .57, p < .05). Noninvasive imaging by 18F-FDG PET is useful for evaluating the therapeutic effects of irbesartan and reflects inflammation, a key factor involved in the therapeutic effects.

The effect of angiotensin-converting enzyme inhibition on inflammatory and angiogenic factors in hypercholesterolemia

BACKGROUND

Renin-angiotensin system (RAS) can be activated during hyperlipidemia. Angiotensin II increases the migration of monocytes, cytokine levels, and gene expressions of VEGF and VCAM-1. With this in mind, the present work attempted to investigate the effect of angiotensin-converting enzyme (ACE) inhibition on VEGF, VCAM-1, and nitric oxide (NO) serum levels in hypercholesterolemic rats.

METHODS

Forty male Wistar rats were divided into 4 groups including normal diet+saline injection (control), hypercholesterol diet+saline injection, normal diet+captopril injection, and hypercholesterol diet+captopril injection. Before and after the beginning of the diet and after the treatment, the serum levels of cholesterol, triglycerides, LDL, HDL, and NO were measured. Finally, gene expressions of VCAM-1 and VEGF in the vascular cells from aorta were determined.

RESULTS

Hypercholesterolemic diet increased the serum levels of cholesterol, LDL (p<0.001), triglycerides (p<0.01) and decreased HDL (p<0.001). Captopril caused a reduction in the serum levels of cholesterol, LDL (p<0.001), and triglycerides (p<0.05) as well as an increase in HDL levels (p<0.01). Although the serum levels of NO decreased after hypercholesterolemic diet (p<0.001), no significant change was observed after the treatment. Increased gene expressions of VEGF (p<0.05) and VCAM-1 (p<0.01) in hypercholesterolemia were regressed in captopril treated rats (p<0.01 and p<0.05, respectively).

CONCLUSION

Captopril, an ACE inhibitor, improves hyperlipidemia and prevents from overexpression of genes for VEGF and VCAM-1, that are implicated in the inflammation and angiogenesis.

Valsartan blocked alcohol-induced, Toll-like receptor 2 signaling-mediated inflammation in human vascular endothelial cells

BACKGROUND

Alcohol consumption induces inflammatory damage in vessels, and the underlying mechanism is unclear. Valsartan, as one of the angiotensin receptor blockers (ARBs), plays a role in the inhibition of inflammatory reactions in vascular dysfunction. This study is to investigate the role of Toll-like receptor 2 (TLR2) in alcohol-induced inflammatory damage in vascular endothelial cells in vitro and to explore the protective effect of valsartan on alcohol-induced and TLR2-mediated inflammatory damage.

METHODS

The human umbilical vein cell line (EA.hy926) were exposed to alcohol at 0 to 80 mM for 0 to 48 hours with or without valsartan pretreatment. The expression of TLR2 signaling, including TLR2, tumor necrosis factor receptor associated factor 6 (TRAF-6) and nuclear factor kappa B (NF-κB) p65 were detected by Western blot. The levels of proinflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), were determined by ELISA. To confirm the role of TLR2, we functionally up-regulated or down-regulated TLR2 by using TLR2 agonist or TLR2 small interfering RNA (siRNA), respectively. To further investigate the mechanism of alcohol on renin-angiotensin system, we detected the expression of angiotensin II receptor type 1 (AGTR1) in protein levels.

RESULTS

The expression of TLR2, TRAF-6, NF-κB p65, and the proinflammatory cytokines, TNF-α and IL-6, were significantly increased after alcohol exposure in EA.hy926 endothelial cells. This was enhanced by TLR2 agonist, and was inhibited by TLR2 siRNA transfection. The pretreatment of valsartan resulted in an inhibition of TLR2 signaling and proinflammatory cytokines. The expression of AGTR1 was up-regulated after alcohol exposure, and was blocked by valsartan pretreatment.

CONCLUSIONS

TLR2 signaling-mediated alcohol induced inflammatory response in human vascular epithelial cells in vitro, which was inhibited by valsartan.

Update on the role of angiotensin in the pathophysiology of coronary atherothrombosis

BACKGROUND

Coronary atherothrombosis due to atherosclerotic plaque rupture or erosion is frequently associated with acute coronary syndromes (ACS). Significant efforts have been made to elucidate the pathophysiological mechanisms underlying acute coronary events.

MATERIALS AND METHODS

This narrative review is based on the material searched for and obtained via PubMed up to August 2014. The search terms we used were as follows: 'angiotensin, acute coronary syndromes, acute myocardial infarction' in combination with 'atherosclerosis, vulnerability, clinical trial, ACE inhibitors, inflammation'.

RESULTS

Among several regulatory components, the renin-angiotensin system (RAS) was shown as a key pathway modulating coronary atherosclerotic plaque vulnerability. Indeed, these molecules are involved in all stages of atherogenesis. Classically, the RAS is composed by a series of enzymatic reactions leading to the angiotensin (Ang) II generation and activity. However, the knowledge of RAS has expanded and become more complex. The discovery of novel components and their functions has revealed additional pathways that contribute to or counterbalance the actions of Ang II. In this review, we discussed on recent findings concerning the role of different angiotensin peptides in the pathophysiology of ACS and coronary atherothrombosis, exploring the link between these molecules and atherosclerotic plaque vulnerability.

CONCLUSIONS

Treatments selectively targeting angiotensins (including Mas and AT2 agonists, ACE2 recombinant, or Ang-(1-7) and almandine in oral formulations) have been tested in animal studies or in small human subgroups, expanding the perspective in the ACS prevention. These novel strategies, especially in the counter-regulatory axis ACE2/Ang-(1-7)/Mas, might be promising to reduce plaque vulnerability and inflammation.

ACE inhibitors potently reduce vascular inflammation, results of an open proof-of-concept study in the abdominal aortic aneurysm

BACKGROUND

Independent of their blood pressure lowering effect, ACE inhibitors are thought to reduce vascular inflammation. The clinical relevance of this effect is unclear with the current knowledge. Abdominal aortic aneurysms (AAA) are characterized by a broad, non-specific inflammatory response, and thus provide a clinical platform to evaluate the anti-inflammatory potential of ACE inhibitors.

METHODS AND RESULTS

Eleven patients scheduled for open AAA repair received ramipril (5 mg/day) during 2-4 weeks preceding surgery. Aortic wall samples were collected during surgery, and compared to matched samples obtained from a biobank. An anti-inflammatory potential was evaluated in a comprehensive analysis that included immunohistochemistry, mRNA and protein analysis. A putative effect of ACE inhibitors on AAA growth was tested separately by comparing 18-month growth rate of patients on ACE inhibitors (n = 82) and those not taking ACE inhibitors (n = 204). Ramipril reduces mRNA expression of multiple pro-inflammatory cytokines such as IL-1β, IL-6, IL-8, TNF -α, Interferon-[Formula: see text], and MCP-1, as well as aortic wall IL-8 and MCP-1 (P = 0.017 and 0.008, respectively) protein content. The is followed by clear effects on cell activation that included a shift towards anti-inflammatory macrophage (M2) subtype. Evaluation of data from the PHAST cohort did not indicate an effect of ACE inhibitors on 18-month aneurysm progression (mean difference at 18 months: -0.24 mm (95% CI: -0.90-0.45, P = NS).

CONCLUSIONS

ACE inhibition quenches multiple aspects of vascular inflammation in AAA. However, this does not translate into reduced aneurysm growth.

TRIAL REGISTRATION

Nederlands Trial Register 1345.

Prehypertension: Underlying pathology and therapeutic options

Prehypertension (PHTN) is a global major health risk that subjects individuals to double the risk of cardiovascular disease (CVD) independent of progression to overt hypertension. Its prevalence rate varies considerably from country to country ranging between 21.9% and 52%. Many hypotheses are proposed to explain the underlying pathophysiology of PHTN. The most notable of these implicate the renin-angiotensin system (RAS) and vascular endothelium. However, other processes that involve reactive oxygen species, the inflammatory cytokines, prostglandins and C-reactive protein as well as the autonomic and central nervous systems are also suggested. Drugs affecting RAS have been shown to produce beneficial effects in prehypertensives though such was not unequivocal. On the other hand, drugs such as β-adrenoceptor blocking agents were not shown to be useful. Leading clinical guidelines suggest using dietary and lifestyle modifications as a first line interventional strategy to curb the progress of PHTN; however, other clinically respected views call for using drugs. This review provides an overview of the potential pathophysiological processes associated with PHTN, abridges current intervention strategies and suggests investigating the value of using the "Polypill" in prehypertensive subjects to ascertain its potential in delaying (or preventing) CVD associated with raised blood pressure in the presence of other risk factors.

Use of renin-angiotensin inhibitors in people with renal artery stenosis

BACKGROUND AND OBJECTIVES

People with atherosclerotic renal artery stenosis may benefit from renin-angiotensin inhibitors, angiotensin-converting enzyme inhibitors, and angiotensin-receptor blockers, but little is known about the factors associated with their use.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Cardiovascular Outcomes in Renal Atherosclerotic Lesions study (ClinicalTrials.gov identified: NCT00081731) is a prospective, international, multicenter clinical trial that randomly assigned participants with atherosclerotic renal artery stenosis who received optimal medical therapy to stenting versus no stenting from May 2005 through January 2010. At baseline, medication information was available from 853 of 931 randomly assigned participants. Kidney function was measured by serum creatinine-based eGFR at a core laboratory.

RESULTS

Before randomization, renin-angiotensin inhibitors were used in 419 (49%) of the 853 participants. Renin-angiotensin inhibitor use was lower in those with CKD (eGFR<60 ml/min per 1.73 m(2)) (58% versus 68%; P=0.004) and higher in individuals with diabetes (41% versus 27%; P<0.001). Presence of bilateral renal artery stenosis or congestive heart failure was not associated with renin-angiotensin inhibitor use. Although therapy with renin-angiotensin inhibitors varied by study site, differences in rates of use were not related to the characteristics of the site participants. Participants receiving a renin-angiotensin inhibitor had lower systolic BP (mean ± SD, 148 ± 23 versus 152 ± 23 mmHg; P=0.003) and more often had BP at goal (30% versus 22%; P=0.01).

CONCLUSIONS

Kidney function and diabetes were associated with renin-angiotensin inhibitor use. However, these or other clinical characteristics did not explain variability among study sites. Patients with renal artery stenosis who received renin-angiotensin inhibitor treatment had lower BP and were more likely to be at treatment goal.

Suppressive effects of irbesartan on inflammation and apoptosis in atherosclerotic plaques of apoE-/- mice: molecular imaging with 14C-FDG and 99mTc-annexin A5

OBJECTIVES

To investigate the effects of irbesartan on inflammation and apoptosis in atherosclerotic plaques by histochemical examination and molecular imaging using (14)C-FDG and (99m)Tc-annexin A5.

BACKGROUND

Irbesartan has a peroxisome proliferator-activated receptor gamma (PPARγ) activation property in addition to its ability to block the AT1 receptor. Accordingly, irbesartan may exert further anti-inflammatory and anti-apoptotic effects in atherosclerotic plaques. However, such effects of irbesartan have not been fully investigated. Molecular imaging using (18)F-FDG and (99m)Tc-annexin A5 is useful for evaluating inflammation and apoptosis in atherosclerotic plaques.

METHODS

Female apoE(-/-) mice were treated with irbesartan-mixed (50 mg/kg/day) or irbesartan-free (control) diet for 12 weeks (n = 11/group). One week after the treatment, the mice were co-injected with (14)C-FDG and (99m)Tc-annexin A5, and cryostat sections of the aortic root were prepared. Histochemical examination with Movat's pentachrome (plaque size), Oil Red O (lipid deposition), Mac-2 (macrophage infiltration), and TUNEL (apoptosis) stainings were performed. Dual-tracer autoradiography was carried out to evaluate the levels of (14)C-FDG and (99m)Tc-annexin A5 in plaques (%ID×kg). In vitro experiments were performed to investigate the mechanism underlying the effects.

RESULTS

Histological examination indicated that irbesartan treatment significantly reduced plaque size (to 56.4%±11.1% of control), intra-plaque lipid deposition (53.6%±20.2%) and macrophage infiltration (61.9%±20.8%) levels, and the number of apoptotic cells (14.5%±16.6%). (14)C-FDG (43.0%±18.6%) and (99m)Tc-annexin A5 levels (45.9%±16.8%) were also significantly reduced by irbesartan treatment. Irbesartan significantly suppressed MCP-1 mRNA expression in TNF-α stimulated THP-1 monocytes (64.8%±8.4% of un-treated cells). PPARγ activation was observed in cells treated with irbesartan (134%±36% at 3 µM to 3329%±218% at 81 µM) by a PPARγ reporter assay system.

CONCLUSIONS

Remissions of inflammation and apoptosis as potential therapeutic effects of irbesartan on atherosclerosis were observed. The usefulness of molecular imaging using (18)F-FDG and (99m)Tc-annexin A5 for evaluating the therapeutic effects of irbesartan on atherosclerosis was also suggested.

Effect of candesartan on the expression of sclera-choroidal intercellular adhesion molecule-1 in hypercholesterolemic models

OBJECTIVE

To evaluate the effect of blocking the angiotensin II AT-1 receptor by the systemic administration of candesartan on the expression of intercellular adhesion molecule-1 in the sclera and choroid of hypercholesterolemic rabbits.

METHODS

New Zealand rabbits were divided into 3 groups, as follows: GI, which was fed a rabbit standard diet; GII, which was fed a hypercholesterolemic diet; and GIII, which received hypercholesterolemic diet plus candesartan. Samples of the rabbits' sclera and choroid were then studied by hematoxylin-eosin staining and histomorphometric and immunohistochemical analyses for intercellular adhesion molecule-1 expression.

RESULTS

Histological analysis of hematoxylin- and eosin-stained sclera and choroid revealed that macrophages were rarely present in GI, and GII had significantly increased macrophage numbers compared to GIII. Moreover, in GII, the sclera and choroid morphometry showed a significant increase in thickness in comparison to GI and GIII. GIII presented a significant increase in thickness in relation to GI. Sclera and choroid immunohistochemical analysis for intercellular adhesion molecule-1 expression revealed a significant increase in immunoreactivity in GII in relation to GI and GIII. GIII showed a significant increase in immunoreactivity in relation to GI.

CONCLUSION

Candesartan reduced the expression of intercellular adhesion molecule-1 and consequently macrophage accumulation in the sclera and choroid of hypercholesterolemic rabbits.

LOX-1, OxLDL, and atherosclerosis

Oxidized low-density lipoprotein (OxLDL) contributes to the atherosclerotic plaque formation and progression by several mechanisms, including the induction of endothelial cell activation and dysfunction, macrophage foam cell formation, and smooth muscle cell migration and proliferation. Vascular wall cells express on their surface several scavenger receptors that mediate the cellular effects of OxLDL. The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is the main OxLDL receptor of endothelial cells, and it is expressed also in macrophages and smooth muscle cells. LOX-1 is almost undetectable under physiological conditions, but it is upregulated following the exposure to several proinflammatory and proatherogenic stimuli and can be detected in animal and human atherosclerotic lesions. The key contribution of LOX-1 to the atherogenic process has been confirmed in animal models; LOX-1 knockout mice exhibit reduced intima thickness and inflammation and increased expression of protective factors; on the contrary, LOX-1 overexpressing mice present an accelerated atherosclerotic lesion formation which is associated with increased inflammation. In humans, LOX-1 gene polymorphisms were associated with increased susceptibility to myocardial infarction. Inhibition of the LOX-1 receptor with chemicals or antisense nucleotides is currently being investigated and represents an emerging approach for controlling OxLDL-LOX-1 mediated proatherogenic effects.

Role of the angiotensin converting enzyme 1/angiotensin II/angiotensin receptor 1 axis in interstitial collagenase expression in human carotid atheroma

BACKGROUND AND AIM

Angiotensin II (AII) receptor 1 (ATR1) and angiotensin converting enzyme 1 (ACE1) blockers have been shown to reduce acute cardiovascular events in patients, improve plaque stability and modify matrix metalloproteinase (MMP) expression. However, the role of the ACE1/AII/ATR1 axis in interstitial collagenase regulation has not been fully explored. In this study, we investigated the effect of ATR1 and ACE1 blockade on the expression and activity of MMP-1, -8 and -13 in human carotid atheroma.

METHODS

Atheroma samples (n = 24) were obtained from patients undergoing carotid endarterectomy. The effects of ATR1 (irbesartan), ACE1 (quinapril), ACE2 (DX600) and MMP (GM6001) blockade on the expression of AII, the interstitial collagenases and soluble elastin fragments were investigated in explant culture supernatants. Paired atheroma samples were incubated with intervention or media control for 4 days. Protein levels (AII, MMP-1, -8, -13 and soluble elastin) were determined by ELISA.

RESULTS

ATR1, but not ACE1, blockade significantly reduced MMP-1 and -8 concentrations in atheroma supernatants. ACE2 blockade significantly increased MMP-1 and -8 concentrations in atheroma supernatants. AII concentration in atheroma supernatants significantly increased after ATR1, ACE1 and ACE2 blockade. Release of soluble elastin fragments increased after ATR1 and ACE1 blockade, but was not changed by an MMP inhibitor.

CONCLUSIONS

Our findings suggest that ATR1 blockade alters AII, MMP-1, MMP-8 expression and a marker of elastin degradation in human atheroma, but that the elastin degradation response is not MMP driven. This data contributes to the recognised ability of ATR1 blockade to modify plaque stability.

The effect of AVE 0991, nebivolol and doxycycline on inflammatory mediators in an apoE-knockout mouse model of atherosclerosis

BACKGROUND

The aim of this study was to investigate whether the 3 different substances that can decrease the development of atherosclerosis--nebivolol, AVE 0991 and doxycycline--could at the same time diminish the level of inflammatory indicators interleukin-6 (IL-6), interleukin-12 (IL-12), serum amyloid A (SAA), and monocyte chemotactic protein-1 (MCP-1).

MATERIAL/METHODS

Forty 8-week-old female apoE-knockout mice on the C57BL/6J background were divided into 4 groups and put on chow diet for 4 months. Three experimental groups received the same diet as a control group, mixed with AVE 0991 at a dose 0.58 µmol per kg of body weight per day, nebivolol at a dose 2.0 µmol per kg of body weight per day, and doxycycline at a dose 1.5 mg per kg of body weight per day. At the age of 6 months, the mice were sacrificed.

RESULTS

All inflammatory indicators (MCP-1, IL-6, IL-12 and SAA) were diminished by AVE 0991. There was also a tendency to lower MCP-1, IL-6, IL-12 and SAA levels by nebivolol and doxycycline; however, it did not reach statistical significance.

CONCLUSIONS

Of the 3 presented substances, only AVE 0991 was able to diminish the rise of inflammatory markers. Therefore, drug manipulations in the renin-angiotensin-aldosterone axis seem to be the most promising in the future treatment of atherogenesis.

Demographics of carotid atherosclerotic plaque features imaged by computed tomography

OBJECTIVES

This was a prospective, cross-sectional study to evaluate the risk factors and symptoms associated with specific carotid wall and atherosclerotic plaque features as seen on computed tomography-angiography (CTA) studies.

MATERIALS AND METHODS

A total of 120 consecutive consenting patients admitted to the emergency department with suspected cerebrovascular ischemia, and receiving standard-of-care CTA of the brain and neck on a 64-slice CT scanner, were prospectively enrolled in the study. The carotid wall features observed on CT were quantitatively analyzed with customized software using different radiodensities for contrast-phase acquisition of the carotids. Clinical datasets, including a complete medical history and examination, were obtained by research physicians or specially trained associates blinded to any findings on CT. Univariate and multivariate analyses were performed to assess the degree of association between clinical indicators and quantitative CT features of carotid atherosclerotic plaques.

RESULTS

Men tended to have increased carotid lumen (coefficient: 608.7; 95% CI: 356.9-860.6; P<0.001) and wall volumes (209.2; 54.5-364.0; P=0.008), and hypertension was associated with increased wall volume (260.6; 88.7-432.6; P=0.003). Advanced age was associated with increases in maximum wall thickness (0.02; 0.003-0.05; P=0.029), fibrous cap thickness (0.005; 0.001-0.008; P=0.016) and number of calcium voxels (2.7; 1.25-4.2; P<0.001), and the presence of a carotid bruit was associated with carotid stenosis length (21.0; 5.38-37.8; P=0.009). Exercise was inversely related to the number of calcium (-37.1; -71.5 - -2.7; P=0.035) and lipid (-7.9; -15.1 - -0.7; P=0.032) voxels. ACE inhibitor use was associated with fibrous cap thickness (0.1; 0.04-0.23; P=0.005).

CONCLUSION

Significant associations were found between clinical descriptors and carotid atherosclerotic plaque features as revealed by CT. Future studies are needed to validate our findings, and to continue investigations into whether CT features of carotid plaques can be used as biomarkers to quantify the impact of strategies aiming to correct vascular risk factors.

The angiotensin-converting enzyme 2/angiotensin-(1-7)/Mas receptor axis: a potential target for treating thrombotic diseases

Despite many therapeutic advances leading to increasingly effective drug treatments, thrombotic events (such as ischaemic stroke, pulmonary embolism, deep venous thrombosis and acute myocardial infarction) still represent a major worldwide cause of morbidity and mortality. Remarkable effort has been made to identify new drug targets. There is growing evidence indicating that the recently described counter-regulator axis of the renin-angiotensin system (RAS), composed of Angiotensin-Converting Enzyme 2 (ACE2), Angiotensin-(1-7) and the Mas receptor, has protective effects against thrombosis. In addition, it could be considered as a promising target for treating or preventing this disease. In this narrative review, we focused on the recent findings of the role of the ACE2/Angiotensin-(1-7)/Mas axis on the haemostatic process and its therapeutic potential.

Angiotensin converting enzyme inhibitor and HMG-CoA reductase inhibitor as adjunct treatment for persons with HIV infection: a feasibility randomized trial

BACKGROUND

Treatments that reduce inflammation and cardiovascular disease (CVD) risk among individuals with HIV infection receiving effective antiretroviral therapy (ART) are needed.

DESIGN AND METHODS

We conducted a 2 × 2 factorial feasibility study of lisinopril (L) (10 mg daily) vs L-placebo in combination with pravastatin (P) (20 mg daily) vs P-placebo among participants receiving ART with undetectable HIV RNA levels, a Framingham 10 year risk score (FRS) ≥ 3%, and no indication for ACE-I or statin therapy. Tolerability and adherence were evaluated. Longitudinal mixed models assessed changes in blood pressure (BP), blood lipids, and inflammatory biomarkers from baseline through months 1 and 4.

RESULTS

Thirty-seven participants were randomized and 34 [lisinopril/pravastatin (n=9), lisinopril/P-placebo (n=8), L-placebo/pravastatin (n=9), L-placebo/P-placebo (n=8)] attended at least one follow-up visit. Participants were 97% male, 41% white, 67% were current smokers, and 65% were taking a protease inhibitor. Median age was 48 years, CD4 count 483 cells/mm(3), FRS 7.79%, total cholesterol 184 mg/dL, and LDL-C 95 mg/dL. There was no treatment difference for pravastatin vs P-placebo in total cholesterol, LDL-C, or any of the inflammatory biomarkers. Participants randomized to lisinopril vs. L-placebo had significant declines in diastolic BP (-3.3 mmHg, p=0.05), hsCRP (-0.61 µg/mL, p=0.02) and TNF-α (-0.17 pg/mL, p=0.04). Participants taking lisinopril vs L-placebo were more likely to report missed doses (88 vs 35%; p=0.001) and have adherence <90% by pill count (42 vs. 0%; p=0.02). Few participants from either group reported side effects (n=3 vs. n=1).

CONCLUSIONS

The modest BP changes and decreased adherence with lisinopril and absence of lipid differences with pravastatin suggest future studies of these drug classes should consider a run-in period to assess adherence and use a different statin. Our results also indicate that ACE-I therapy may have anti-inflammatory benefits for ART-treated persons with HIV infection and this should be further evaluated.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00982189.

Biology of intracranial aneurysms: role of inflammation

Intracranial aneurysms (IAs) linger as a potentially devastating clinical problem. Despite intense investigation, our understanding of the mechanisms leading to aneurysm development, progression and rupture remain incompletely defined. An accumulating body of evidence implicates inflammation as a critical contributor to aneurysm pathogenesis. Intracranial aneurysm formation and progression appear to result from endothelial dysfunction, a mounting inflammatory response, and vascular smooth muscle cell phenotypic modulation producing a pro-inflammatory phenotype. A later final common pathway appears to involve apoptosis of cellular constituents of the vessel wall. These changes result in degradation of the integrity of the vascular wall leading to aneurysmal dilation, progression and eventual rupture in certain aneurysms. Various aspects of the inflammatory response have been investigated as contributors to IA pathogenesis including leukocytes, complement, immunoglobulins, cytokines, and other humoral mediators. Furthermore, gene expression profiling of IA compared with control arteries has prominently featured differential expression of genes involved with immune response/inflammation. Preliminary data suggest that therapies targeting the inflammatory response may have efficacy in the future treatment of IA. Further investigation, however, is necessary to elucidate the precise role of inflammation in IA pathogenesis, which can be exploited to improve the prognosis of patients harboring IA.

Angiotensin converting enzyme 2 and atherosclerosis

Angiotensin converting enzyme 2 (ACE2) is a homolog of angiotensin converting enzyme (ACE) which generates angiotensin II from angiotensin I. ACE, its product angiotensin II and the downstream angiotensin type I receptor are important components of the renin-angiotensin system (RAS). Angiotensin II, the most important component of the RAS, promotes the development of atherosclerosis. The identification of ACE2 in 2000 opened a new chapter of research on the regulation of the RAS. ACE2 degrades pro-atherosclerotic angiotensin II and generates anti-atherosclerotic angiotensin 1-7. In this review, we explored the importance of ACE2 in protecting experimental animals from developing atherosclerosis and its involvement in human atherosclerosis. We also examined the published evidence assessing the importance of ACE2 in different cell types relevant to atherosclerosis and putative underlying cellular and molecular mechanisms linking ACE2 with protection from atherosclerosis. ACE2 shifts the balance from angiotensin II to angiotensin 1-7 inhibiting the progression of atherosclerosis in animal models.