Polymorphisms in the human angiotensin converting enzyme gene (ACE) linked to susceptibility of COVID-19 and malaria infections in the Ghanaian population

Genetic variations in the human angiotensin converting enzyme gene (ACE) influence ACE enzyme expression levels in humans and subsequently influence both communicable and non-communicable disease outcomes. More recently, polymorphisms in this gene have been linked to susceptibility and outcomes of infectious diseases such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and malaria infections. This study is the first to investigate the genetic diversity of ACE and ACE2 polymorphisms in the Ghanaian population. Archived filter blood blot samples from malaria patients aged ≤9 years were used. Molecular analysis for the detection of ACE rs4646994 (I/D), ACE2 rs2106809 (C/T) and rs2285666 (G/A) alleles as well as ACE2 exons 1-4 polymorphisms was conducted on 300 samples. The D allele (54%,162/300) was the most dominant polymorphism observed in the ACE rs4646994 gene whilst the G (68%, 204/300) and T alleles (59.3%,178/300) were the most frequent ACE2 rs2285666 and rs2106809 polymorphisms observed. For the 300 samples sequenced for ACE2 exons 1-4, analyses were done on 268, 282 and 137 quality sequences for exons 1, 2 and 3-4 respectively. For exon 1, the mutation D38N (2.2%; 6/268) was the most prevalent. The S19P and E37K mutations previously reported to influence COVID-19 infections were observed at low frequencies (0.4%, 1/268 each). No mutations were observed in exon 2. The N121K/T variants were the most seen in exons 3-4 at frequencies of 5.1% (K121, 7/137) and 2.9% (T121, 4/137) respectively. Most of the variants observed in the exons were novel compared to those reported in other populations in the world. This is the first study to investigate the genetic diversity of ACE and ACE2 genes in Ghanaians. The observation of novel mutations in the ACE2 gene is suggesting selection pressure. The importance of the mutations for communicable and non-communicable diseases (malaria and COVID-19) are further discussed.

Chronic hypoxia impairs skeletal muscle repair via HIF-2α stabilization

BACKGROUND

Chronic hypoxia and skeletal muscle atrophy commonly coexist in patients with COPD and CHF, yet the underlying physio-pathological mechanisms remain elusive. Muscle regeneration, driven by muscle stem cells (MuSCs), holds therapeutic potential for mitigating muscle atrophy. This study endeavours to investigate the influence of chronic hypoxia on muscle regeneration, unravel key molecular mechanisms, and explore potential therapeutic interventions.

METHODS

Experimental mice were exposed to prolonged normobaric hypoxic air (15% pO2, 1 atm, 2 weeks) to establish a chronic hypoxia model. The impact of chronic hypoxia on body composition, muscle mass, muscle strength, and the expression levels of hypoxia-inducible factors HIF-1α and HIF-2α in MuSC was examined. The influence of chronic hypoxia on muscle regeneration, MuSC proliferation, and the recovery of muscle mass and strength following cardiotoxin-induced injury were assessed. The muscle regeneration capacities under chronic hypoxia were compared between wildtype mice, MuSC-specific HIF-2α knockout mice, and mice treated with HIF-2α inhibitor PT2385, and angiotensin converting enzyme (ACE) inhibitor lisinopril. Transcriptomic analysis was performed to identify hypoxia- and HIF-2α-dependent molecular mechanisms. Statistical significance was determined using analysis of variance (ANOVA) and Mann-Whitney U tests.

RESULTS

Chronic hypoxia led to limb muscle atrophy (EDL: 17.7%, P < 0.001; Soleus: 11.5% reduction in weight, P < 0.001) and weakness (10.0% reduction in peak-isometric torque, P < 0.001), along with impaired muscle regeneration characterized by diminished myofibre cross-sectional areas, increased fibrosis (P < 0.001), and incomplete strength recovery (92.3% of pre-injury levels, P < 0.05). HIF-2α stabilization in MuSC under chronic hypoxia hindered MuSC proliferation (26.1% reduction of MuSC at 10 dpi, P < 0.01). HIF-2α ablation in MuSC mitigated the adverse effects of chronic hypoxia on muscle regeneration and MuSC proliferation (30.9% increase in MuSC numbers at 10 dpi, P < 0.01), while HIF-1α ablation did not have the same effect. HIF-2α stabilization under chronic hypoxia led to elevated local ACE, a novel direct target of HIF-2α. Notably, pharmacological interventions with PT2385 or lisinopril enhanced muscle regeneration under chronic hypoxia (PT2385: 81.3% increase, P < 0.001; lisinopril: 34.6% increase in MuSC numbers at 10 dpi, P < 0.05), suggesting their therapeutic potential for alleviating chronic hypoxia-associated muscle atrophy.

CONCLUSIONS

Chronic hypoxia detrimentally affects skeletal muscle regeneration by stabilizing HIF-2α in MuSC and thereby diminishing MuSC proliferation. HIF-2α increases local ACE levels in skeletal muscle, contributing to hypoxia-induced regenerative deficits. Administration of HIF-2α or ACE inhibitors may prove beneficial to ameliorate chronic hypoxia-associated muscle atrophy and weakness by improving muscle regeneration under chronic hypoxia.

The frequency of the ACE I/D polymorphism in South America: a systematic review and meta-analysis

Angiotensin-converting enzyme (ACE) is a key component of the renin-angiotensin system and plays an important role in homeostasis and maintenance of blood pressure. However, little is known about allele and genotypic frequencies, as well as phenotypic characteristics associated with ACE polymorphism genotypes in South American populations. This study aimed to verify the allelic predominance and genotype frequency of ACE I/D polymorphism in South America and its association with the main diseases and related conditions. We conducted a systematic review considering studies published in the last 25 years available in PubMed, Scielo, LILACS, LIPECS, Coleciona SUS, CUMED, BINACIS, IBECS, and MEDLINE databases, resulting in the inclusion of 121 studies. Quality of the studies was assessed according to the Strengthening the Reporting of Genetic Association (STREGA) guidelines. We mapped the frequency of the ACE I/D polymorphism in South American populations. 8,856 (32.1%) subjects were DD, 13,050 were ID (47.4%), and 5,644 were II (20.5%) carriers. The main associated conditions included systemic arterial hypertension and other cardiovascular conditions, cardiorespiratory or respiratory characteristics, physical activity level, kidney conditions, aging-related diseases, as well as different types of cancers and metabolic conditions. 61.1% of the studies found no significant association between the respective conditions investigated and the ACE I/D polymorphism. Considering DD genotype or D allele, 21.5% of the studies observed negative and 4.9% positive outcomes. Regarding ID genotype, 4.1% of the studies identified negative and 0.8% positive outcomes, and for II genotype or I allele, 4.1% of the results had negative and 10.7% positive associations.

Screening of angiotensin converting enzyme inhibitors from natural products via origami microfluidic paper-based analytical devices with colorimetric detection

We report the screening of angiotensin converting enzyme (ACE) inhibitors on an origami microfluidic paper-based analytical device (μPAD) using colorimetric detection. The hydrolysis product reacts with ninhydrin, resulting in a purple color at the detection zones. Images of the μPADs are captured using a common cell phone and analyzed with Photoshop software. This platform allows six independent colorimetric reactions to take place simultaneously, and the IC50 values can be obtained in a single run within 22 min. The relative standard deviations of inhibition efficiencies are generally lower than 4.0 % (n = 5). The IC50 values of captopril and five products from natural plants were obtained and corresponded well with UV methods. The relative deviations between the two methods are within the range of -5 % to +5 %. This work is a proof-of-concept successfully demonstrating the use of μPADs technology to screen enzyme inhibitors from natural products.

The 'Insertion/Deletion' Polymorphism, rs4340 and Diabetes Risk: A Pilot Study from a Hospital Cohort

The insertion/deletion, I/D polymorphism, in the gene encoding Angiotensin Converting Enzyme, ACE is a popular genetic marker for cardiovascular disease, CVD. With alarming rise in diabetes, the risk of CVD among Indian subjects is further enhanced. The present study explored the role of ACE I/D polymorphism, rs4340 as a genetic marker and its association with diabetes. Genomic DNA, isolated from a cohort of 410 urban subjects attending our hospital, was genotyped using polymerase chain reaction followed by electrophoresis. Among the subjects, 84 had type-2 diabetes and 68 had hypertension while 258 were free from these risk factors. Majority (57/84) of diabetic subjects were also suffering from hypertension. Genotype frequencies of ACE I/D polymorphism, of diabetic (84) patients were not different from that of non-diabetic subjects (258). In sharp contrast, we found significant differences, in genotype frequencies of women with diabetes (n = 38) compared to non-diabetic women (70). Diabetic women had significantly higher prevalence of the high risk 'D' allele. Analysis of odds ratio, OR revealed that women with 'D/D' genotype, exhibited threefold risk (OR 3.12, 95% CI 1.21-8.05; p = 0.018) of diabetes, in the recessive model (D/D vs I/I + I/D). Further when we analysed Odds ratio of diabetic women (8) who were free from hypertension, the results revealed even a greater, 6- fold (OR 6.0, 95% CI 1.29-27.96, p = 0.027) risk of diabetes for D/D homozygous women (D/D vs I/I + I/D). These results suggest 'sex-specific' association of ACE 'I/D' polymorphism, with type-2 diabetes, affecting women while there was no influence observed among men. In view of the increased cardiovascular mortality among Indians, data from our pilot study if confirmed in a larger cohort, could add value to our future intervention efforts.

Genetic Variations of Angiotensinogen, Angiotensin Converting Enzyme, and Angiotensin Type 1 Receptor with the Risk of Pulmonary Tuberculosis

There is little data regarding the impact of renin-angiotensin system (RAS) gene polymorphisms on tuberculosis. The current study designed to survey the possible association between RAS polymorphisms and the risk of pulmonary tuberculosis (PTB) in a sample of the southeast Iranian population. This case-control study was done on 170 PTB patients and 170 healthy subjects. The AGT rs699 C>T, ACE rs4341 C>G and AT1R rs5186 C>A variants were genotyped using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and ACE rs4646994 (287bp I/D) variant by PCR method. Regarding AT1R rs5186 A>C polymorphism, the findings revealed that AC genotype and C allele significantly decreased the risk of PTB (OR=0.39, 95% CI=0.22-0.67, p=0.001, and OR=0.53, 95% CI=0.25-0.72, p=0.002, C vs. A, respectively). The TC genotype and C allele of AGT rs699 T>C significantly associated with decreased the risk of PTB (OR=0.45, 95% CI=0.28-0.74, p=0.002, TC vs. TT and OR=0.51, 95% CI=0.32-0.80, p=0.005, C vs. T, respectively). The ID genotype of ACE 287bp I/D significantly increased the risk of PTB (OR=1.88, 95% CI=1.12-3.17, p=0.017). Our finding did not support an association between ACE rs4341 C>G variant and the risk of PTB. In summary, the findings revealed an association between AT1R rs5186 A>C, AGT rs699 T>C and ACE 287bp I/D polymorphisms and the risk of PTB in a sample of the southeast Iranian population. Further investigation with higher sample sizes and diverse ethnicities are required to confirm our findings.

Dataset on substituents effect on biological activities of linear RGD-containing peptides as potential anti-angiotensin converting enzyme

The angiotensin converting enzyme inhibiting activity of linear rgd-containing peptides was investigated using in silico approach. The synthesized compound (parent compound) using experimental approach as well as its derivatives was subjected to computational examination using appropriate software. The investigated compounds were optimized using Spartan 14 while the docking study was executed via Pymol, AutoDock Tool, AutoDock Vina and discovery studio. The descriptors obtained (2D and 3D) were screened and the descriptor with highest capacity (squared correlation coefficient) was correlated to the calculated binding affinity. More so, the docking analysis was performed on the investigated linear rgd-containing peptides and angiotensin converting enzyme (PDB ID: 3nxq) via docking software and the resulted scoring and the types of the interaction observed were presented. Furthermore, (S)-dimethyl 2-(2-((S)-2-((R)-1-((S)-2-((S)-2-((S)-3-(4-chlorophenyl)-2-(1,3-dioxoisoindolin-2-yl)propanamido)-4-(methylthio)butanamido)-4-methylpentanoyl)pyrrolidine-2-carboxamido)-5-(3-((2,2,4,5,7-pentamethyl-2,3-dihydrobenzofuran-6-yl)sulfonyl)guanidino)pentanamido)acetamido)succinate (AB5) (compound with lowest binding affinity) and metformin were subjected to ADMET analysis and the resulted outcome were reported appropriately.

Potential long-term neurological and gastrointestinal effects of COVID-19: A review of adult cohorts

BACKGROUND

The respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evolved into a multi-organ disorder, with long-term effects known as post-acute sequelae of SARS-CoV-2 infection or long coronavirus disease (COVID).

AIM

To examine the current knowledge and outcomes of long-term neurological and gastrointestinal (GI) symptoms in adult cohorts, including United States minority populations.

METHODS

PubMed and Google Scholar were searched using relevant terms, and data from five studies were analyzed, comprising 27383 patients with persistent neurological and GI sequelae.

RESULTS

The main symptoms included anxiety, depression, dysphagia, headache, vomiting, nausea, gastroesophageal reflux, fatigue, and abdominal pain. Patients with comorbidities and metabolic syndromes were at higher risk for long COVID. While most patients were European Americans, there was a need for further study on African Americans.

CONCLUSION

The underlying causes of these symptoms remain unclear, warranting more investigation into the long-term impact of the SARS-CoV-2 on different populations.

Is chymase 1 a therapeutic target in cardiovascular disease?

INTRODUCTION

Non-angiotensin converting enzyme mechanisms of angiotensin II production remain underappreciated in part due to the success of current therapies to ameliorate the impact of primary hypertension and atherosclerotic diseases of the heart and the blood vessels. This review scrutinize the current literature to highlight chymase role as a critical participant in the pathogenesis of cardiovascular disease and heart failure.

AREAS COVERED

We review the contemporaneous understanding of circulating and tissue biotransformation mechanisms of the angiotensins focusing on the role of chymase as an alternate tissue generating pathway for angiotensin II pathological mechanisms of action.

EXPERT OPINION

While robust literature documents the singularity of chymase as an angiotensin II-forming enzyme, particularly when angiotensin converting enzyme is inhibited, this knowledge has not been fully recognized to clinical medicine. This review discusses the limitations of clinical trials' that explored the benefits of chymase inhibition in accounting for the failure to duplicate in humans what has been demonstrated in experimental animals.

Formaldehyde causes an increase in blood pressure by activating ACE/AT1R axis

Previous studies suggest some link between formaldehyde exposure and harmful cardiovascular effects. But whether exposure to formaldehyde can cause blood pressure to rise, and if so, what the underlying mechanism is, remains unclear. In this study, C57BL/6 male mice were exposed to 0.1, 0.5, 2.5 mg/m³ of gaseous formaldehyde for 4 h daily over a three-week period. The systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP) and heart rate (HR) of the mice were measured by tail-cuff plethysmography, and any histopathological changes in the target organs of hypertension were investigated. The results showed that exposure to formaldehyde did cause a significant increase in blood pressure and heart rate, and resulted in varying degrees of damage to the heart, aortic vessels and kidneys. To explore the underlying mechanism, a specific inhibitor of angiotensin converting enzyme (ACE) was used to block the ACE/AT1R axis. We observed the levels of ACE and angiotensin II type 1 receptor (AT1R), as well as the bradykinin (BK) in cardiac cytoplasm. The data suggest that exposure to formaldehyde induced an increase in the expression of ACE and AT1R, and decreased the levels of BK. Strikingly, treatment with 5 mg/kg/d ACE inhibitor can attenuate the increase in blood pressure and the pathological changes caused by formaldehyde exposure. This result has improved our understanding of whether, and how, formaldehyde exposure affects the development of hypertension.

Angiotensin-converting enzyme gene (ACE) polymorphisms are associated with dysregulation of biochemical parameters in hypertensive patients

INTRODUCTION

The genetic component, including genes and their variants, plays a significant role in the pathophysiology of arterial hypertension (AH). Thus, clinical, epidemiological and genetic studies have been carried out to improve the understanding of disease mechanisms, improve diagnostic quality and contribute to prevention.

OBJECTIVE

To determine the association of risk factors, biochemical parameters and different ACE gene polymorphisms with AH.

METHOD

The case-control study was carried out in the population of Ouro Preto, Brazil. The subjects answered a questionnaire containing clinical and sociodemographic data. The ACE gene polymorphisms rs4291, rs4363 and rs4335 were evaluated by real time-polymerase chain reaction (real-time PCR) in 310 people (155 hypertensive and 155 normotensive patients), in addition to biochemical parameters. A multivariate logistic regression model was used to identify factors associated with AH. Analysis of continuous variables was performed using the Kruskal-Wallis test to assess significance between groups and Dunn's post-test for multiple comparisons.

RESULTS

The results showed that AH was associated with age, education, smoking, obesity and high levels of triglycerides, sodium, glucose and uric acid. Regarding the biochemical parameters, in hypertensive patients, the rs4363 and rs4335 polymorphisms were associated with high levels of triglycerides, urea and glucose; the rs4291 polymorphism was associated with elevated urea and glucose levels. No association was detected between SNPs and HA.

CONCLUSION

AH was associated with socioeconomic status, lifestyle habits and biochemical parameters. ACE polymorphisms may have influenced the levels of triglycerides, urea and glucose in hypertensive patients.

Antihypertensive activity of roasted cashew nut in mixed petroleum fractions-induced hypertension: An in vivo and in silico approaches

Consumption of water polluted by crude oil is a major environmental problem typical in exploration areas. Numerous health complications such as high blood pressure, myocardial infarction, and other heart complications are prevalent and ravaging. These have gradually become age-defiling disease conditions that are usually maintained with lifestyle changes and diet control. The effect of dietary supplementation with 10% and 20% roasted cashew nuts (RCN) on systolic blood pressure and angiotensin converting enzyme I (ACE I) activities in mixed petroleum fraction (MPF) induced toxicity was studied in male Wistar rats through the modulation of the renin-angiotensin system. The phytochemicals in RCN were quantified using the high performance liquid chromatography (HPLC) technique. To predict likely binding affinity and stability, computational methods such as molecular docking, ADME, and molecular dynamic simulation were used. Out of the seven phytochemicals identified, rutin, gallic acid, and quercetin had the greatest quantities. Similarly, rutin had the highest binding affinities with ACE I, -10.7 kcal/mol, followed by quercetin, at -9.1 kcal/mol. During the molecular dynamics simulation, all of the identified phytochemicals demonstrated good pharmacokinetic capabilities and remained stable at their respective binding sites. Subsequent in vivo validation studies revealed that RCN was able to attenuate the effect of MPF by significantly (p < 0.05) lowering the systolic blood pressure and ACE I activity in comparison to the reference medication, atenolol. We recommend that cashew nuts be explored as dietary snacks as well as a low-cost, easily available component of supplements for the treatment of high blood pressure.

Does the Naked Emperor Parable Apply to Current Perceptions of the Contribution of Renin Angiotensin System Inhibition in Hypertension?

PURPOSE OF REVIEW

To address contemporary hypertension challenges, a critical reexamination of therapeutic accomplishments using angiotensin converting enzyme inhibitors and angiotensin II receptor blockers, and a greater appreciation of evidence-based shortcomings from randomized clinical trials are fundamental in accelerating future progress.

RECENT FINDINGS

Medications targeting angiotensin II mechanism of action are essential for managing primary hypertension, type 2 diabetes, heart failure, and chronic kidney disease. While the ability of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers to control blood pressure is undisputed, practitioners, hypertension specialists, and researchers hold low awareness of these drugs' limitations in preventing or reducing the risk of cardiovascular events. Biases in interpreting gained knowledge from data obtained in randomized clinical trials include a pervasive emphasis on using relative risk reduction over absolute risk reduction. Furthermore, recommendations for clinical practice in international hypertension guidelines fail to address the significance of a residual risk several orders of magnitude greater than the benefits. We analyze the limitations of the clinical trials that have led to current recommended treatment guidelines. We define and quantify the magnitude of the residual risk in published hypertension trials and explore how activation of alternate compensatory bioprocessing components within the renin angiotensin system bypass the ability of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers to achieve a significant reduction in total and cardiovascular deaths. We complete this presentation by outlining the current incipient but promising potential of immunotherapy to block angiotensin II pathology alone or possibly in combination with other antihypertensive drugs. A full appreciation of the magnitude of the residual risk associated with current renin angiotensin system-based therapies constitutes a vital underpinning for seeking new molecular approaches to halt or even reverse the cardiovascular complications of primary hypertension and encourage investigating a new generation of ACE inhibitors and ARBs with increased capacity to reach the intracellular compartments at which Ang II can be generated.

Impact of renin-angiotensin system inhibitors on outcomes in patients with metastatic renal cell carcinoma treated with immune-checkpoint inhibitors

BACKGROUND

Renin-angiotensin system inhibitors (RASi) have been shown to improve outcomes in studies of multiple malignancies by effects on the tumor microenvironment to enhance the immune repertoire and improve drug delivery. Repurposing RASi to treat metastatic renal cell carcinoma (mRCC) in combination with immune-checkpoint inhibitors (ICI) may improve survival coupled with tolerability and cost efficacy. We evaluated the impact of RASi on outcomes in mRCC patients receiving ICI.

METHODS

This multicenter, retrospective cohort study included mRCC patients treated with ICI with or without RASi. The patients from Dana-Farber Cancer Institute (DFCI) were used as a discovery cohort, and the patients from University of California San Diego (UCSD) were used for validation. Receipt of an ICI (PD1/L1 and/or CTLA-4 inhibitors) was required. RASi use was defined as receipt of a RASi at baseline and for a minimum of 30 days after ICI initiation. For both the discovery and validation cohorts, the primary outcome assessed was overall survival (OS) and the secondary endpoints were time-to-treatment failure (TTF), and objective response rate (ORR).

RESULTS

Overall, 229 patients who received an ICI were included: 100 patients from DFCI and 129 patients from UCSD. Concomitant RASi were administered in 30 patients (30%) in the DFCI cohort and 59 (45%) in the UCSD cohort. Median age at ICI initiation was 62.5 years in both cohorts. Median follow-up was 3.8 [IQR 3-5.3] years in the DFCI cohort, and 2.3 [IQR 1.4-3.6] years in the UCSD cohort. In the DFCI cohort, RASi was significantly associated with longer OS (adjusted-HR 0.35 [95% CI, 0.17-0.70], P = .003) and TTF (adjusted-HR 0.57 [0.36-0.92], P = .02). In the validation cohort, RASi was associated with TTF (adjusted HR, 0.60 [0.39-0.92], P = .02) and not statistically associated with OS (adjusted-HR 0.60 [0.34-1.06], P = .07). The propensity analysis, matching 83 patients from both cohorts receiving RASi while on ICI with 83 who did not, showed that RASi significantly improved OS (HR 0.59 [0.37-0.95], P = .03) and TTF (HR 0.60 [0.43-0.85], P = .0034).

CONCLUSIONS

RASi was associated with improved OS and TTF in mRCC patients receiving ICI. This provides a rationale for prospective randomized studies combining ICI and RASi in mRCC patients.

The Impact of COVID-19 on Cancer Recurrence: A Narrative Review

Severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) continues to be a worldwide healthcare problem. While our knowledge of the interaction of cancer and its management with COVID-19 mortality is gradually evolving, there are still many unanswered questions regarding the impact of COVID-19 on cancer and its prognosis. Several factors activated during COVID-19 have been implicated in tumorigenesis and the development of metastasis. Inflammation, hypoxia, reduced levels of angiotensin converting enzyme 2, elevated levels of Interleukin 6 and some other cytokines that are hallmarks of COVID-19 are capable of inducing tumor relapse and metastasis. On the other hand, there are reports that COVID-19 has been associated with cancer cure. Understanding the interaction between COVID-19 and tumor cells is essential for evaluating the potential long-term risks of COVID-19 in cancer patients, and for scheduling necessary preventive and therapeutic interventions. In this review, we briefly overview the potential impacts that COVID-19 might have on tumorigenesis and cancer relapse, as well as the role that COVID-19 might play in cancer remission and cure.

Targeting brain Renin-Angiotensin System for the prevention and treatment of Alzheimer's disease: Past, present and future

Alzheimer's disease (AD) is a well-known neurodegenerative disease characterized by the presence of two main hallmarks - Tau hyperphosphorylation and Aβ deposits. Notwithstanding, in the last few years the scientific evidence about the drivers of AD have been changing and nowadays age-related vascular alterations and several cardiovascular risk factors have been shown to trigger the development of AD. In this context, drugs targeting the Renin Angiotensin System (RAS), commonly used for the treatment of hypertension, are evidencing a high potential to delay AD development due to their action on brain RAS. Indeed, the ACE 1/Ang II/AT1R axis is believed to be upregulated in AD and to be responsible for deleterious effects such as increased oxidative stress, neuroinflammation, blood-brain barrier (BBB) hyperpermeability, astrocytes dysfunction and a decrease in cerebral blood flow. In contrast, the alternative axis - ACE 1/Ang II/AT2R; ACE 2/Ang (1-7)/MasR; Ang IV/ AT4R(IRAP) - seems to counterbalance the deleterious effects of the principal axis and to exert beneficial effects on memory and cognition. Accordingly, retrospective studies demonstrate a reduced risk of developing AD among people taking RAS medication as well as several in vitro and in vivo pre-clinical studies as it is herein critically reviewed. In this review, we first revise, at a glance, the pathophysiology of AD focused on its classic hallmarks. Secondly, an overview about the impact of the RAS on the pathophysiology of AD is also provided, focused on their four essential axes ACE 1/Ang II/AT2R; ACE 2/Ang (1-7)/MasR; Ang IV/ AT4R(IRAP) and ACE 1/Ang II/AT1R. Finally, the therapeutic potential of available drugs targeting RAS on AD, namely angiotensin II receptor blockers (ARBs) and angiotensin converting enzyme inhibitors (ACEIs), is highlighted and data supporting this hope will be presented, from in vitro and in vivo pre-clinical to clinical studies.

Diminazene Aceturate, an angiotensin converting enzyme 2 (ACE2) activator, promotes cardioprotection in ischemia/reperfusion-induced cardiac injury

This study aimed to investigate whether the Diminazene Aceturate (DIZE), an angiotensin-converting enzyme 2 (ACE2) activator, can revert cardiac dysfunction in ischemia reperfusion-induced (I/R) injury in animals and examine the mechanism underlying this effect. Wistar rats systemically received DIZE (1 mg/kg) for thirty days. Cardiac function in isolated rat hearts was evaluated using the Langendorff technique. After I/R, ventricular non-I/R and I/R samples were used to evaluate ATP levels. Mitochondrial function was assessed using cardiac permeabilized fibers and isolated cardiac mitochondria. Cardiac cellular electrophysiology was evaluated using the patch clamp technique. DIZE protected the heart after I/R from arrhythmia and cardiac dysfunction by preserving ATP levels, independently of any change in coronary flow and heart rate. DIZE improved mitochondrial function, increasing the capacity for generating ATP and reducing proton leak without changing the specific citrate synthase activity. The activation of the ACE2 remodeled cardiac electrical profiles, shortening the cardiac action potential duration at 90 % repolarization. Additionally, cardiomyocytes from DIZE-treated animals exhibited reduced sensibility to diazoxide (K_ATP agonist) and a higher K_ATP current compared to the controls. DIZE was able to improve mitochondrial function and modulate cardiac electrical variables with a cardio-protective profile, resulting in direct myocardial cell protection from I/R injury.

Functional ACE2 deficiency leading to angiotensin imbalance in the pathophysiology of COVID-19

SARS-CoV-2, the virus responsible for COVID-19, uses angiotensin converting enzyme 2 (ACE2) as its primary cell-surface receptor. ACE2 is a key enzyme in the counter-regulatory pathway of the broader renin-angiotensin system (RAS) that has been implicated in a broad array of human pathology. The RAS is composed of two competing pathways that work in opposition to each other: the "conventional" arm involving angiotensin converting enzyme (ACE) generating angiotensin-2 and the more recently identified ACE2 pathway that generates angiotensin (1-7). Following the original SARS pandemic, additional studies suggested that coronaviral binding to ACE2 resulted in downregulation of the membrane-bound enzyme. Given the similarities between the two viruses, many have posited a similar process with SARS-CoV-2. Proponents of this ACE2 deficiency model argue that downregulation of ACE2 limits its enzymatic function, thereby skewing the delicate balance between the two competing arms of the RAS. In this review we critically examine this model. The available data remain incomplete but are consistent with the possibility that the broad multisystem dysfunction of COVID-19 is due in large part to functional ACE2 deficiency leading to angiotensin imbalance with consequent immune dysregulation and endothelial cell dysfunction.

Analysis of the Pattern, Alliance and Risk of rs1799752 (ACE I/D Polymorphism) with Essential Hypertension

Studies in spontaneously hypertensive rat had revealed an elevated level of ACE gene expression in the tissues and is substantiated by experimental clinical studies for a positive correlation between ACE I/D polymorphism and hypertension. Aim: To determine whether the polymorphic variant of ACE gene in intron 16 confers susceptibility to essential hypertension. I/D polymorphism at the locus intron 16 of the ACE gene were amplified from the genomic DNA of the total 571 (hypertensive patients, n: 279; controls, n: 292) participants using polymerase chain reaction and gel electrophoresis methods and were examined in a case-control approach. Suitable descriptive statistics was used for different variables. Result revealed significant heterogeneity under the allele (p: 0.0002) and genotype (p: 0.0001) contrast in hypertensive patients than in normal controls, with an increased frequency of D allele (62.72%; p < 0.0001; OR: 1.8144; 95% CI: 1.4327-2.2979) and DD genotype (41.93%; p: < 0.0001). A significant association was found in the DD variant with disease phenotype (p: 0.0018, 95% CI: 1.3303-3.4907; OR: 2.1549; Table 31) and is substantiated by the data of multivariate analysis, demonstrating a statistically significant increase in odds of hypertension with the ACE D/D genotype (OR: 2.09; 95% CI: 1.24-2.91). Conspicuously, subgroup analysis by gender did not change this pattern of results. Albeit the allele distribution resulted in a higher frequency of the D/D genotype in the cases than controls, testing genetic equilibrium between the observed and expected genotypes using Hardy-Weinberg equilibrium showed ACE gene variants were confirming to the law in hypertensive as well as in non-hypertensive participants. I/D polymorphism in the angiotensin-I-converting enzyme gene at the 16th intron can be useful for outcome predictions during diagnostic processes can be implicated in an individual's propensity for hypertension and thus implies that genetic variants of ACE I/D might serve as a predictor for the susceptibility to hypertension.

Cardioprotective effects of Talinum paniculatum (Jacq.) Gaertn. in doxorubicin-induced cardiotoxicity in hypertensive rats

ETHNOPHARMACOLOGICAL RELEVANCE

Talinum paniculatum (Jacq.) Gaertn. (Talinaceae) is a medicinal species that is widely distributed throughout Brazil. Popularly known as "major-gomes," the species is used in folk medicine for the treatment of cardiovascular disorders.

AIM OF THE STUDY

To evaluate the effect of an ethanolic extract of T. paniculatum (EETP) in rats with renovascular hypertension and heart failure and determine its chemical composition.

MATERIALS AND METHODS

First, EETP was obtained, and its chemical profile was analyzed by LC-DAD-MS. The acute toxicity was evaluated in female Wistar rats. The model of renovascular hypertension was established in male Wistar rats by combining the Goldblatt 2K1C method and intraperitoneal doxorubicin administration for 6 weeks. The animals were then treated daily with EETP (30, 100, and 300 mg/kg) or metoprolol (25 mg/kg) by gavage for 28 days. The negative control group was treated with vehicle (filtered water). The sham group consisted of animals that were not subjected to 2K1C or cardiotoxicity and were treated with vehicle. Renal function was evaluated on days 1, 14, and 28. At the end of treatment, the electrocardiographic profile, blood pressure, and mesenteric vascular reactivity were investigated. Serum urea, creatinine, angiotensin converting enzyme, nitrotyrosine, malondialdehyde, nitrite, aldosterone, and sodium and potassium levels were measured. The heart, aorta artery, liver, and right kidney were collected, weighed, and processed for histopathological analysis. Cardiac chambers also underwent morphometric analysis.

RESULTS

No signs of toxicity were observed in female Wistar rats. Thirty-two compounds were annotated from EETP, including flavonoids, chlorogenic acids, and saponins. EETP treatment resulted in a significant cardiorenal-protective response, normalizing electrocardiographic and hemodynamic alterations, and preventing ventricle remodeling. These effects were associated with serum antioxidant activity and angiotensin-converting enzyme (ACE) inhibition.

CONCLUSION

The present study demonstrated that EETP may exert cardioprotective effects through serum antioxidant activity and ACE inhibition, preventing alterations of hemodynamic and endothelial function, and reducing damage to cardiac structure. Thus, EETP, especially at the 100 and 300 mg/kg doses, may be useful for preventing doxorubicin-induced cardiotoxicity in hypertensive patients.

Age and genotype dependent erythropoietin protection in COVID-19

Erythropoietin (EPO) is the main mediator of erythropoiesis and an important tissue protective hormone that appears to mediate an ancestral neuroprotective innate immune response mechanism at an early age. When the young brain is threatened-prematurity, neonatal hyperbilirubinemia, malaria- EPO is hyper-secreted disproportionately to any concurrent anemic stimuli. Under eons of severe malarial selection pressure, neuroprotective EPO augmenting genetic determinants such as the various hemoglobinopathies, and the angiotensin converting enzyme (ACE) I/D polymorphism, have been positively selected. When malarial and other cerebral threats abate and the young child survives to adulthood, EPO subsides. Sustained high ACE and angiotensin II (Ang II) levels through the ACE D allele in adulthood may then become detrimental as witnessed by epidemiological studies. The ubiquitous renin angiotensin system (RAS) influences the α-klotho/fibroblast growth factor 23 (FGF23) circuitry, and both are interconnected with EPO. Here we propose that at a young age, EPO augmenting genetic determinants through ACE D allele elevated Ang II levels in some or HbE/beta thalassemia in others would increase EPO levels and shield against coronavirus disease 2019, akin to protection from malaria and dengue fever. Human evolution may use ACE2 as a “bait” for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) to gain cellular entry in order to trigger an ACE/ACE2 imbalance and stimulate EPO hypersecretion using tissue RAS, uncoupled from hemoglobin levels. In subjects without EPO augmenting genetic determinants at any age, ACE2 binding and internalization upon SARS-CoV-2 entry would trigger an ACE/ACE2 imbalance, and Ang II oversecretion leading to protective EPO stimulation. In children, low nasal ACE2 Levels would beneficially augment this imbalance, especially for those without protective genetic determinants. On the other hand, in predisposed adults with the ACE D allele, ACE/ACE2 imbalance, may lead to uncontrolled RAS overactivity and an Ang II induced proinflammatory state and immune dysregulation, with interleukin 6 (IL-6), plasminogen activator inhibitor, and FGF23 elevations. IL-6 induced EPO suppression, aggravated through co-morbidities such as hypertension, diabetes, obesity, and RAS pharmacological interventions may potentially lead to acute respiratory distress syndrome, cytokine storm and/or autoimmunity. HbE/beta thalassemia carriers would enjoy protection at any age as their EPO stimulation is uncoupled from the RAS system. The timely use of rhEPO, EPO analogs, acetylsalicylic acid, bioactive lipids, or FGF23 antagonists in genetically predisposed individuals may counteract those detrimental effects.

Renal biomarkers of acute kidney injury in response to increasing intermittent hypoxia episodes in the neonatal rat

BACKGROUND

We tested the hypotheses that: 1) early exposure to increasing episodes of clinically relevant intermittent hypoxia (IH) is detrimental to the developing kidneys; and 2) there is a critical number of daily IH episodes which will result in irreparable renal damage that may involve angiotensin (Ang) II and endothelin (ET)-1.

METHODS

At birth (P0), neonatal rat pups were exposed to brief IH episodes from the first day of life (P0) to P7 or from P0-P14. Pups were either euthanized immediately or placed in room air (RA) until P21. RA littermates served as controls. Kidneys were harvested at P7, P14, and P21 for histopathology; angiotensin converting enzyme (ACE), ACE-2, ET-1, big ET-1, and malondialdehyde (MDA) levels; immunoreactivity of ACE, ACE-2, ET-1, ET-2, ET receptors (ETAR, ETBR), and hypoxia inducible factor (HIF)1α; and apoptosis (TUNEL stain).

RESULTS

Histopathology showed increased renal damage with 8-12 IH episodes/day, and was associated with Ang II, ACE, HIF1α, and apoptosis. ACE-2 was not expressed at P7, and minimally increased at P14. However, a robust ACE-2 response was seen during recovery with maximum levels noted in the groups recovering from 8 IH episodes/day. ET-1, big ET-1, ETAR, ETBR, and MDA increased with increasing levels of neonatal IH.

CONCLUSIONS

Chronic neonatal IH causes severe damage to the developing kidney with associated elevations in vasoconstrictors, suggesting hypertension, particularly with 8 neonatal IH episodes. ACE-2 is not activated in early postnatal life, and this may contribute to IH-induced vasoconstriction. Therapeutic targeting of ACE and ET-1 may help decrease the risk for kidney injury in the developing neonate to prevent and/or treat neonatal acute kidney injury and/or chronic kidney disease.

Intolerance to Angiotensin Converting Enzyme Inhibitors in Asthma and the General Population: A UK Population-Based Cohort Study

BACKGROUND

Angiotensin converting enzyme inhibitor (ACEI) intolerance commonly occurs, requiring switching to an angiotensin-II receptor blocker (ARB). Angiotensin converting enzyme inhibitor intolerance may be mediated by bradykinin, potentially affecting airway hyperresponsiveness.

OBJECTIVE

To assess the risk for switching to ARBs in asthma.

METHODS

We conducted a new-user cohort study of ACEI initiators identified from electronic health records from the UK Clinical Practice Research Datalink. The risk for switching to ARBs in people with asthma or chronic obstructive pulmonary disease and the general population was compared. Adjusted hazard ratios (HRs) were calculated using Cox regression, stratified by British Thoracic Society (BTS) treatment step and ACEI type.

RESULTS

Of 642,336 new users of ACEI, 6.4% had active asthma. The hazard of switching to ARB was greater in people with asthma (HR = 1.16; 95% confidence interval [CI], 1.14-1.18; P ≤ .001) and highest in those at BTS step 3 or greater (HR = 1.35, 95% CI, 1.32-1.39; and HR = 1.18, 95% CI, 1.15-1.22, P ≤ .001 for patients aged ≥60 and <60 years, respectively). Hazard was highest with enalapril (HR = 1.25, 95% CI, 1.18-1.34, P ≤ .001; HR = 1.44, 95% CI, 1.32-1.58, P ≤ .001 for BTS step 3 or greater asthma). No increased hazard was observed in chronic obstructive pulmonary disease or those younger than age 60 years at BTS step 1/2. The number needed to treat varied by age, sex, and body mass index (BMI), ranging between 21 and 4, and was lowest in older women with a BMI of 25 or greater.

CONCLUSIONS

People with active asthma are more likely to switch to ARBs after commencing ACEI therapy. The number needed to treat varies by age, sex, BMI, and BTS step. Angiotensin-II receptor blocker could potentially be considered first-line in people with asthma and in those with high-risk characteristics.

Interaction of SARS-CoV-2 spike protein with angiotensin converting enzyme inhibitors and selected compounds from the chemical entities of biological interest

BACKGROUND

Recent COVID-19 outbreak has prompted the search of novel therapeutic agents to treat the disease. The initial step of the infection involves the binding of the virus through the viral spike protein with the host angiotensin converting enzyme 2 (ACE2). In this study, the interaction of some ACE or ACE2 inhibitors and their analogues as well as selected compounds with the viral spike protein as a strategy to hinder viral-ACE2 interaction were investigated. SARS-CoV-2 spike protein as well as the ligands were retrieved from protein databank and ChEBI database respectively. The molecules were prepared before initiating the virtual screening using PyRx software. Discovery studio was used to further visualize the binding interactions between the compounds and the protein.

RESULTS

The ACE inhibitors and their analogues fosinopril (1-), fosinopril and moexipril have the best binding affinity to the protein with binding energies < - 7.0 kcal/mol while non-flavonoid stilben-4-ol binds with free binding energy of - 7.1 kcal/mol. Others compounds which belong to either the flavonoids, terpenes and alkaloid classes also have binding energies  < - 7.0 kcal/mol. Such high binding energies were enhanced via hydrogen bond (h-bond) interactions in addition to other interactions observed between the compounds and the amino acid residues of the protein.

CONCLUSIONS

The ACE inhibitors and their analogues as well as the selected compounds could serve as inhibitors of the spike protein as well as lead in drug discovery processes to target the SARS-CoV-2 virus.

Bacille calmette-guérin: An ophthalmic perspective

Vaccines such as bacille Calmette-Guérin (BCG) are known for their heterologous effects mediated through a number of mechanisms, including trained immunity constituted by monocyte-macrophage based innate immunity. Other events such as direct hematogenous spread and induction of autoimmunity are also described. There has been a resurgent interest in harnessing some of the benefits of trained immunity in the management of COVID-19, even as several specific vaccines have been approved. We summarize the current knowledge of ocular effects of BCG. Potential effect of granulomatous inflammation on angiotensin converting enzyme activity and accentuation of cytokine storm that may result in undesirable ocular and systemic effects are also discussed.

Angiotensin-converting Enzyme Inhibitors: Can it be a Potential Treatment of Infantile Hemangioma

Aims

The aim of the sudy was to evaluate potential role of oral captopril, an angiotensin-converting enzyme (ACE) inhibitor, and in treatment of infantile hemagioma (IH) and report our preliminary results.

Methods

This prospective study included 18 children with IH admitted in the department of pediatric surgery with no history of prior treatment of any type. Baseline blood pressure (BP), electrocardiogram, two-dimensional echocardiography, serum electrolytes, and renal function test (RFT) were noted. Oral captopril was started as first-line drug at a dose of 0.1 mg/kg orally 12 h with gradually increase of dosage up to 2.0 mg/kg 12 h over the period of 10 days with monitoring of BP, serum electrolytes, RFT, and occurrence of any side effect. If no side effects were noted and patients were stable, they were discharged and followed up until 6 months after stopping treatment. During follow-up, response to treatment was documented clinically and photographically. Development of any side effect was also noted.

Results

Excellent response to captopril was noticed in nine patients over 16-18 months. Four patients showed good response. Oral propranolol had to be administered alternatively in one patient showing fair response during the initial 4 months but no response afterward and in four patients showing no response at all. One patient developed an allergic reaction to propranolol and was started oral corticosteroid. These five patients had near complete resolution of lesion for the next 8-10 months.

Conclusions

ACE inhibitors might have a role, though slow, in the involution of IHs. Therefore, these may have the potential to emerge as an alternative treatment for IH in future after confirmation with randomized studies with propranolol.

Lung cancer in the older population:Interactive effects of angiotensin converting enzyme gene polymorphism (rs 4340 ID) and tobacco addiction in risk assessment

BACKGROUND

rs4340ID polymorphism of angiotensin-converting enzyme (ACE) correlates with serum ACE levels in many known cancers. This study analyzed ACE rs4340 ID polymorphism in lung cancer (LC) in older patients of North India and correlated it with addiction status.

METHODS

The study enrolled all subjects aged 60 years and above with 154 LC and 205 healthy controls. Genotyping was done by polymerase chain reaction (PCR) and validated by sequencing of 10% of the sample. Statistical analysis was done by SPSS Statistics 21.

RESULTS

Genotype II was observed to have a significant 2.21-fold increased risk of LC as compared to the DD genotype and 3.43-folds enhanced risk with interaction of I allele with tobacco consumption habits as compared to D allele in LC was seen.

CONCLUSION

The risk of LC was higher with II genotype as compared to DD genotype. Interactive effect showed that I allele with tobacco habits may increase the risk of LC.

Association between angiotensin converting enzyme gene polymorphism and essential hypertension: A systematic review and meta-analysis

Background:

The current meta-analytic study explored the relation between ACE gene insertion/deletion (I/D), and the risk of EH by reviewing relevant trials so as to determine the association between Angiotensin Converting Enzyme (ACE) gene polymorphism and essential hypertension (EH) susceptibility.

Methods:

Relevant studies published before May 2019 were collected from the PubMed, Cochrane, Embase, CNKI, VANFUN, and VIP databases.

Results:

Fifty-seven studies involving a total of 32,862 patients were included. These studies found that ACE gene D allele was associated with higher EH susceptibility in allelic model, homozygote model, dominant model, and regressive model, and that Asian population with ACE gene D allele showed a higher EH susceptibility in all these models. Moreover, ACE gene D allele was found closely related to a higher EH susceptibility in the subgroups of HWE, NO HWE, Caucasian population, and Mixed population, with the majority being males in allelic model, homozygote model, and regressive model and the majority being females in allelic model.

Conclusion:

ACE gene D allele is associated with an overall higher EH susceptibility, which is confirmed in the subgroup analysis of Asian population, HWE, NO HWE, Caucasian population, and Mixed population.

Inhibition of angiotensin converting enzyme induces mechanical allodynia through increasing substance P expression in mice

Although emerging evidence shows that angiotensin converting enzyme (ACE) is associated with pain, it is not clear whether inhibition of ACE could affect to nociceptive transmission and which mediators are involved in this process. Here we investigated whether administration of the ACE inhibitors, captopril and enalapril increases the expression of substance P (SP) and whether this increase contributes to the induction of mechanical allodynia in mice. ACE was expressed in the lumbar dorsal root ganglion (DRG) and the superficial dorsal horn (SDH) region of the spinal cord in mice. Either intraperitoneal or intrathecal administration of the ACE inhibitors, captopril and enalapril for 10 days significantly increased the paw withdrawal frequency to innocuous mechanical stimuli and the levels of SP in both the lumbar DRG and the SDH region of the spinal cord dorsal horn. In addition, intraperitoneal administration of the SP receptor (neurokinin-1 receptor) antagonist, L-733,060 suppressed mechanical allodynia that was induced by pretreatment of captopril and enalapril. Intraplantar administration of SP for 3 days induces mechanical allodynia, and this effect was reduced by exogenous ACE administration. These findings demonstrate that inhibition of ACE increases the levels of SP in both the lumbar DRG and spinal cord dorsal horn, ultimately contributing to the induction of mechanical allodynia in mice.

Clinical Characteristics of Paediatric Hyperinflammatory Syndrome in the Era of Corona Virus Disease 2019 (COVID-19)

The pandemic of COVID-19 initially appeared to cause only a mild illness in children. However, it is now apparent that a small percentage of children can develop a hyperinflammatory syndrome labeled as Pediatric inflammatory multisystem syndrome—temporally associated with SARS-CoV-2 (PIMS-TS) with a phenotype resembling Kawasaki disease (KD) ('Kawa-COVID-19′). Features of this newly recognized condition may include fever, hypotension, severe abdominal pain and cardiac dysfunction, evidence of inflammation, and single or multi organ dysfunction in the absence of other known infections. Children emerge to have mild symptoms compared to adults, perhaps due to reduced expression of the angiotensin converting enzyme (ACE)-2 receptor (the target of SARS-CoV-2) gene, trained innate immunity, and a young and fit immune system. Some of these children may share features of Kawasaki disease, toxic shock syndrome or cytokine storm syndrome. They can deteriorate rapidly and may need intensive care support as well. The PCR test is more often negative although most of the children have antibodies to SARS-CoV-2. Although the pathogenesis is not clearly known, immune-mediated injury has been implicated.

Comparison of alcalase- and pepsin-treated oilseed protein hydrolysates - Experimental validation of predicted antioxidant, antihypertensive and antidiabetic properties

There is emerging evidence on the importance of food-derived bioactive peptides to promote human health. Compared with animal derived proteins, plant proteins, in particular oilseed proteins, are considered as affordable and sustainable sources of bioactive peptides. Based on our previous bioinformatic analysis, five oilseed proteins (flaxseed, rapeseed, sunflower, sesame and soybean) were enzymatically hydrolysed using alcalase and pepsin (pH 1.3 and pH 2.1). Further, low molecular weight (Mw ​< ​3 ​kDa) fractions were generated using ultrafiltration. The protein hydrolysates and their low Mw fractions were evaluated for their in vitro antioxidant, antihypertensive and antidiabetic capabilities, in comparison with samples obtained from two dairy proteins (whey and casein). Apart from dipeptidyl-peptidase IV inhibition, significantly stronger bioactivities were detected for the low Mw fractions. In partial agreement with in silico predictions, most oilseed hydrolysates exerted comparable angiotensin-converting enzyme inhibitory capability to dairy proteins, whilst whey protein was the most promising source of dipeptidyl-peptidase IV inhibitors. Apart from alcalase-treated soybean, dairy proteins were more efficient in releasing antioxidant peptides as compared to oilseed proteins. On the other hand, soybean protein hydrolysates showed the highest α-glucosidase inhibitory activity amongst all protein sources. Overall, there was limited correlation between in silico predictions and in vitro experimental results. Nevertheless, our results indicate that oilseed proteins have potential as bioactive peptide sources, and they might therefore be suitable replacers for dairy proteins as well as good sources for development of functional foods.

Pulmonary midkine inhibition ameliorates sepsis induced lung injury

Background

Midkine is a multi-functional molecule participating in a various key pathological process. We aimed to evaluate the change of midkine in sepsis and its association with angiotensin-converting enzyme (ACE) system, as well as the mechanism by which midkine induced in sepsis and lung injury.

Methods

The peripheral blood sample of septic patients on admission was obtained and measured for midkine, ACE and angiotensin II. Cecal ligation and puncture (CLP) mouse model was used, and adeno-associated virus (AAV) was stilled trans-trachea for regional targeting midkine expression, comparing the severity of lung injury. Furthermore, we studied the in vitro mechanism of midkine activates ACE system by using inhibitors targeting candidate receptors of midkine, and its effects on the vascular endothelial cells.

Results

Plasma midkine was significantly elevated in sepsis, and was closely associated with ACE system. Both circulating and lung midkine was increased in CLP mouse, and was related to severe lung injury. Regional interfering midkine expression in lung tissue by AAV could alleviate acute lung injury in CLP model. In vitro study elucidated that Notch 2 participated in the activation of ACE system and angiotensin II release, induced by midkine and triggered vascular endothelial injury by angiotensin II induced reactive oxygen species production.

Conclusions

Midkine inhibition ameliorates sepsis induced lung injury, which might via ACE/Ang II pathway and the participation of Notch 2 in the stimulation of ACE.

Trial registration

Clinicaltrials.gov NCT02605681. Registered 12 November 2015

Coagulation abnormalities in SARS-CoV-2 infection: overexpression tissue factor

Among the pathways and mediators that may be dysregulated in COVID-19 infection, there are proinflammatory cytokines, lymphocyte apoptosis, and the coagulation cascade. Venous and arterial thromboembolisms also are frequent in COVID-19 patients with the increased risk of some life-threatening complications such as pulmonary embolism, myocardial infarction, and ischemic stroke. In this regard, overproduction of proinflammatory cytokines such as IL-6, IL-1β, and TNF-α induce cytokine storms, increase the risk of clot formation, platelet activation, and multiorgan failure that may eventually lead to death among these patients. Surface S protein of SARS-CoV-2 binds to its target transmembrane receptor, named as angiotensin converting enzyme 2 (ACE2(, on various cells such as lymphocyte, alveolar cells, monocytes/macrophages, and platelets. Notably, the activation of the coagulation cascade occurs through tissue factor (TF)/FVIIa-initiated hemostasis. Accordingly, TF plays the major role in the activation of coagulation system during viral infection. In viral infections, the related coagulopathy multiple factors such as inflammatory cytokines and viral specific TLRs are involved, which consequently induce TF expression aberrantly. SARS-COV-2 may directly infect monocytes/ macrophages. In addition, TF expression/release from these cells may play a critical role in the development of COVID-19 coagulopathy. In this regard, the use of TF- VIIa complex inhibitor may reduce the cytokine storm and mortality among COVID-19 patients.

Relationship of angiotensin converting enzyme (I/D) polymorphism (rs4646994) and coronary heart disease among a male Iraqi population with type 2 diabetes mellitus

BACKGROUND

Insertion deletion (I/D) polymorphism (rs4646994) in the angiotensin-converting enzyme (ACE) has a substantial effect on coronary heart disease (CHD). The amplification of an Alu repetitive element in an intron of the ACE has shown three potential genotypes of I/I and D/D as homozygous, and I/D as heterozygous.

OBJECTIVE

The objective of this study was to investigate the association between the ACE gene polymorphism and CHD among male Iraqi patients with and without type2 diabetes mellitus (T2DM).

METHODS

A case-control study of total 217 male subjects participated in this study, divided into three groups; Group 1 including 86 CHD patients with T2DM, group 2 including 78 CHD patients without T2DM, and group 3 including 53 age and sex-matched healthy individuals (as a control group). Genotyping of ACE (I/D) gene was performed using polymerase chain reaction (PCR) technique.

RESULTS

The II allele was significantly more frequent in CHD patients without T2DM compared to the control population, but not from those patients with T2DM (p < 0.05). Nonetheless, the ID allele was significantly more frequent in each of CHD with T2DM and control populations compared to the CHD without T2DM. The DD allele was significantly more frequent in CHD patients with T2DM compared to each of CHD patients without T2DM and control populations (p < 0.05).

CONCLUSION

We conclude that the D/D and I/D genotypes are implicated as risk factors for development of CHD with T2DM, but not CHD without T2DM among the male Iraqi population. However, larger sample sizes are needed to monitor the CHD patients and to validate this study.

Origin and genomic characteristics of SARS-CoV-2 and its interaction with angiotensin converting enzyme type 2 receptors, focusing on the gastrointestinal tract

The emergence of coronavirus disease-2019 induced by a newly identified b-coronavirus, namely severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has constituted a public health emergency. Even though it was considered a zoonotic disease, the virus has also spread among humans via respiratory secretions. The expression and distribution of angiotensin converting enzyme type 2 (ACE2) in various human organs might also show other possible infection routes. High ACE2 ribonucleic acid expression has been identified in the gastrointestinal tract (GI) indicating its importance as a possible infection pathway of SARS-CoV-2. ACE2 induces viral entry into the host and most importantly has been found to be associated with the function of the gut. Its deficiency has been implicated in several pathologies such as colorectal inflammation. The renin-angiotensin system (RAS) is an essential regulatory cascade operating both at a local tissue level and at the systemic or circulatory level. The RAS may be important in the pathogenesis of chronic liver disease and is associated with the up-regulation of ACE2. Thus, the aim of this review is firstly, the analysis of some important general and genome characteristics of SARS-CoV-2 and secondly, and most importantly, to focus on the utility of ACE2 receptors in both SARS-CoV-2 replication and pathogenesis, especially in the GI tract.

Gastrointestinal and hepatic manifestations of COVID-19 infection: Lessons for practitioners

Originating from Wuhan in China, coronavirus disease 2019 (COVID-19) spread globally within months and was declared a pandemic by World Health Organization in March 2020, making it one of the biggest healthcare calamities of our time. As more data on COVID-19 infection became available, what was initially thought to be a simple respiratory illness was found to be more complex. Many extra-pulmonary manifestations are now frequently reported for COVID-19 in available literature, most commonly gastrointestinal and hepatopancreato-biliary manifestations. Due to early scarcity of data, extra pulmonary manifestations were initially overlooked and may have contributed to nosocomial spread of the infection. Practitioners, especially gastroenterologists, who frequently encounter patients with these symptoms, need to be aware of them. This can not only help minimize the nosocomial spread, ensure safety of provider but also help conserve already stretched-thin healthcare resources. A tremendous amount of COVID-19 related literature is getting added to the growing pool every day, making it difficult for providers to follow. The aim of our review is to summarize the available evidence for gastrointestinal and hepatopancreatobiliary manifestations of COVID-19. We here briefly discussed the possible pathophysiologic mechanism for these manifestations and summarized the recommendations put forward by multiple gastrointestinal societies regarding safe and effective clinical practice during the ongoing pandemic.

The genetic polymorphisms of angiotensin converting enzyme insertion/deletion and glioma susceptibility: A meta-analysis

Objective:

The previous studies on angiotensin converting enzyme (ACE) insertion/deletion (I/D) genetic polymorphism and glioma risk were inconsistent. Therefore, we performed a meta-analysis to assess the association between ACE I/D polymorphisms and glioma risk.

Methods and Results:

In total, four populations (1110 cases and 1335 controls) on ACE I/D polymorphism were included. Overall, the meta-analysis demonstrated no significant association between ACE I/D polymorphism and glioma risk. In addition, the analysis of the association of ACE I/D polymorphism and clinical grade also showed no significant association.

Conclusion:

Our meta-analysis didn’t find a significant association between ACE I/D polymorphism glioma risk. However, further studies with larger sample size and more ethnic groups are required to confirm the results.

The Pathophysiology, Diagnosis and Treatment of Corona Virus Disease 2019 (COVID-19)

Since the beginning of this century, beta coronaviruses (CoV) have caused three zoonotic outbreaks. However, little is currently known about the biology of the newly emerged SARS-CoV-2 in late 2019. There is a spectrum of clinical features from mild to severe life threatening disease with major complications like severe pneumonia, acute respiratory distress syndrome, acute cardiac injury and septic shock. The genome of SARS-CoV-2 encodes polyproteins, four structural proteins and six accessory proteins. SARS-CoV-2 tends to utilize Angiotensin-converting enzyme 2 (ACE2) of various mammals. The imbalance between ACE/Ang II/AT1R pathway and ACE2/Ang(1-7)/Mas receptor pathway in the renin-angiotensin system leads to multi-system inflammation. The early symptoms of COVID-19 pneumonia are low to midgrade fever, dry cough and fatigue. Vigilant screening is important. The diagnosis of COVID-19 should be based on imaging findings along with epidemiological history and nucleic acid detection. Isolation and quarantine of suspected cases is recommended. Management is primarily supportive, with newer antiviral drugs/vaccines under investigation.

Effect of probiotic cultures on the angiotensin converting enzyme inhibitory activity of whey-based fermented beverages

Fermented whey-based beverages were elaborated using commercial probiotics cultures (CHR HANSEN): BCT-1®, ABT-4®, ABC where A: Lactobacillus acidophilus, B: Bifidobacterium animalis subsp. lactis, C: Lactobacillus paracasei subsp. paracasei and T: Streptococccus thermophiles. Three treatments were prepared with these probiotics cultures and a treatment without cultures added as a control. All beverage were maintained at 4 °C and evaluated during their shelf life at 0, 7, 14 and 21 days. The variables analyzed were peptide concentration, proteolysis, ACE-inhibitory activity and, peptide and aromatic amino acid profiles. Principal component analysis (PCA) was conducted to assess the relationship between these variables. All whey-based fermented beverages added with probiotics presented ACE inhibitory activity (22-100%). However, whey-based beverage without probiotics added had the highest ACE inhibitory activity (100%), and it was maintained during its shelf life. Fermented beverage with ABT-4® culture had an ACE inhibitory activity from 80 to 100% during its shelf life. Thus can be attributed to the release of peptides during processing. Meanwhile, significative correlations were observed between variables varying this depending on the treatment, both, in magnitude and in direct or inverse direction (0.684-0.986). The ACE inhibitory activity was correlated to proteolysis and peptide and aromatic amino acids profiles. And, the IC₅₀ was observed in the range of 0.01-0.055 mg/mL.

Angiotensin-converting enzymes (ACE, ACE2) gene variants and COVID-19 outcome

•

The Angiotensin system has been implicated in the pathogenesis of COVID-19.

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Functional ACE/ACE2 polymorphisms might contribute to the outcome of COVID-19.

•

Severe COVID-19 was associated with hypertension, male gender, and ACE-DD genotype.

•

The ACE2 polymorphism was not associated with the disease outcome.

•

ACE2 showed no coding variants that could explain an increased risk of COVID-19.

The Angiotensin system is implicated in the pathogenesis of COVID-19. First, ACE2 is the cellular receptor for SARS-CoV-2, and expression of the ACE2 gene could regulate the individuaĺs susceptibility to infection. In addition, the balance between ACE1 and ACE2 activity has been implicated in the pathogenesis of respiratory diseases and could play a role in the severity of COVID-19. Functional ACE1/ACE2 gene polymorphisms have been associated with the risk of cardiovascular and pulmonary diseases, and could thus also contribute to the outcome of COVID-19.

We studied 204 COVID-19 patients (137 non-severe and 67 severe-ICU cases) and 536 age-matched controls. The ACE1 insertion/deletion and ACE2 rs2285666 polymorphism were determined. Variables frequencies were compared between the groups by logistic regression. We also sequenced the ACE2 coding nucleotides in a group of patients.

Severe COVID-19 was associated with hypertension male gender (p < 0.001), hypertension (p = 0.006), hypercholesterolaemia (p = 0.046), and the ACE1-DD genotype (p = 0.049). In the multiple logistic regression hypertension (p = 0.02, OR = 2.26, 95%CI = 1.12–4.63) and male gender (p = 0.002; OR = 3.15, 95%CI = 1.56–6.66) remained as independent significant predictors of severity. The ACE2 polymorphism was not associated with the disease outcome. The ACE2 sequencing showed no coding sequence variants that could explain an increased risk of developing COVID-19.

In conclusion, an adverse outcome of COVID-19 was associated with male gender, hypertension, hypercholesterolemia and the ACE1 genotype. Our work suggested that the ACE1-I/D might influence COVID-19 severity, but the effect was dependent on the hypertensive status. This result requires further validation in other large cohorts.

Association of vitamin D with the modulation of the disease severity in COVID-19

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Insufficient levels of Vitamin D could be seen in COVID-19 patients.

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Increase in the ACE could be seen in COVID-19 patients with higher quantities in the individuals who died from the COVID-19.

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The Neutrophil to Lymphocyte ratio (NLR) is higher in COVID-19 than the control group.

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Serum levels of vitamin D and ACE are associated with the progression and severity of the COVID-19.

In late 2019, SARS-CoV-2 started to spread throughout the world causing the COVID-19 that has taken a considerable number of lives. Results obtained from several investigations have explained the virus origin, pathogenicity, and transmission. Similar to SARS coronavirus, the pulmonary angiotensin converting enzyme (ACE) 2 was introduced as the virus receptor for entering the cell. An increased body of epidemiological and clinical evidences has shown modulating effects of vitamin D in lung injuries through several mechanisms. Several clinical symptoms as well as molecular factors have shown to be related to the disease transmission and severity. In this study, vitamin D, ACE concentrations, and neutrophil to lymphocyte ratio (NLR) were measured in patients with confirmed COVID-19 in comparison with control group. Results demonstrated significant alterations in vitamin D and ACE levels as well as NLR in the patients’ group. Contribution of those factors with the prognosis and severity of the disease has been shown.

Serial investigation of Angiotensin-Converting Enzyme in sarcoidosis patients treated with Angiotensin-Converting Enzyme Inhibitor

BACKGROUND

Angiotensin-converting enzyme (ACE) is an acid glycoprotein that converts angiotensin I into angiotensin II. It is produced mainly by activated alveolar macrophages and it resulted elevated in sarcoidosis patients. ACE is the only biomarker mentioned in WASOG international guidelines for the diagnosis and follow-up of sarcoidosis patients but its sensitivity and specificity are low. This study aimed to analyze serial measurements of ACE levels in sarcoidosis patients stratified according to concomitant ACE-inhibitor therapies (ACEIs).

SUBJECTS AND METHODS

136 serum samples from sarcoidosis patients were retrospectively enrolled in the study. Serial ACE concentrations were measured once year for each patient. Population were divided according to radiogical stages and ACEIs.

RESULTS

ACE concentrations resulted higher in non-ACEIs than ACEIs group (p<E-04). This result was confirmed also stratifying population according to radiological stages particularly in stage 3 (p=2E-03) or stage 2 of the disease (p<1E-04). Considering ACEIs, serum ACE levels proved to be higher in sarcoidosis patients treated with zofenopril than in those treated with perindopril (p=2E-02), enalapril (p=2E-03) or ramipril (p=2E-04). Patients treated with ACEIs showed a progressive reduction in ACE levels to five years of follow-up (p=1.3E-02) and the zofenopril group recorded the highest ACE levels (p<1E-04).

CONCLUSIONS

This retrospective study investigated changes in ACE levels in patients with sarcoidosis treated or not treated with ACEIs. Considering the overall low sensitivity and specificity of this biomarker, we suggest systematically investigating medical drugs prescribed for patients with sarcoidosis, in order to optimize the interpretation of ACE in clinical management.

Angiotensin converting enzyme inhibitors and angiotensin receptor blockers have no effect on the outcomes of endovascular revascularization in tibial arterial occlusive disease

The effects of angiotensin converting enzyme inhibitors and angiotensin receptor blockers (ACEI/ARBs) on angiogenesis, myocardial remodeling and intermittent claudication have been studied. Clinical studies have shown reduced re-intervention after cardiac stenting with the use of ACEI/ARBs. We hypothesized that the use of ACEI/ARBs decreases re-interventions after endovascular revascularization in tibial artery disease (TAD) patients. This is a retrospective study comparing the effects of ACEI/ARBs on the outcomes after endovascular revascularization for TAD. We divided all patients that underwent endovascular revascularization into Angiotensin converting enzyme inhibitor/Angiotensin receptor blockers (ACEI/ARBs) and No Angiotensin converting enzyme inhibitor/Angiotensin receptor blockers (NoACEI/ARBs) groups. A total of 360 patients underwent endovascular intervention for TAD. One hundred and ninety-six (54%) patients, 124 (57%) males, were on ACEI/ARBs after endovascular intervention for TAD, whereas 164(46%) patients, 87 (53%) males were not. The groups were well matched in the demographic variables except higher incidence of congestive heart failure, coronary artery disease and dialysis in the ACEI/ARBs group (p = .001, 0.02, 0.01 respectively). Reintervention rates were not associated with ACEI/ARBs use (p = .097). Even when corrected for statin use and antiplatelet therapy, no difference was seen in the reintervention rates in the two groups (p = .535, 0.547 respectively). Primary patency, assisted primary patency and secondary patency did not differ with the use of ACEI/ARBs (p = .244 0.096,0.060 respectively). No difference was seen in overall survival between the two groups (p = .690). ACEI/ARBs do not appear to affect the patency and reintervention rates for patients undergoing endovascular revascularization for TAD.

Pork frankfurters prepared with hydrolyzed whey: Preliminary product quality aspects and inhibitory activity of the resulting peptides on angiotensin-converting enzyme

The objective of this study was to assess the addition of whey protein hydrolysate (WH) on quality and antihypertensive potential of pork frankfurters, as the first step in development of a functional meat product. A hydrolyzed whey protein solution was incorporated in the frankfurter formula according to the following treatments: T0 (30% water), T1 (10% WH, 20% water), T2 (20% WH, 10% water) and T3 (30% WH). Addition of up to 30% WH increased lightness and yellowness, decreased hardness and chewiness by 15% and shear force by 43%, with no effect on pH (6.36) and cooking yield (93%). The WH addition resulted in an increase in the antihypertensive potential (IC₅₀ 258.78 μg/mL) relative to the T0 (IC₅₀ 1548.25 μg/mL). Cold storage of the product with 30% WH did not impact physicochemical quality, nor did it modify the antihypertensive potential. Incorporation of whey hydrolysate into pork frankfurters could be an option for providing antihypertensive peptides in food for health-oriented consumers.

Combinatorial inhibition of Angiotensin converting enzyme, Neutral endopeptidase and Aminopeptidase N by N-methylated peptides alleviates blood pressure and fibrosis in rat model of dexamethasone-induced hypertension

Angiotensin converting enzyme (ACE), neutral endopeptidase (NEP) and aminopeptidase N (APN) are responsible for generation of vasoactive peptides that regulates vasoconstriction, vasodilation and natriuresis, which altogether regulate blood pressure. Cumulative inhibition of ACE, NEP and APN effectively blocks the progression of respective pathways. In this study, N-methylated peptide inhibitors F-N(Me)H-L, V-N(Me)F-R and R-N(Me)V-Y were synthesized against ACE, NEP and APN respectively, using their respective physiological substrates. F-N(Me)H-L inhibited ACE activity with an IC₅₀ of 83 nmol/L, V-N(Me)F-R inhibited NEP activity with an IC₅₀ of 1.173 μmol/L and R-N(Me)V-Y inhibited APN activity with an IC₅₀ of 3.94 nmol/L respectively. Further, the anti-hypertensive effect of N-methylated peptides was evaluated using rat model of dexamethasone-induced hypertension. Individual peptides and their cocktail treatment were started from day 6 of the study period and blood pressure was measured on every alternate day during 15 day study. Administration of F-N(Me)H-L (138 ± 3 mmHg) and cocktail of all the three peptides at a dose of 100 mg/kg significantly reduced systolic blood pressure (SBP) compared to dexamethasone group (SBP of Groups-dexamethasone; (167 ± 5 mmHg), F-N(Me)H-L (138 ± 3 mmHg), and Cocktail (122 ± 3 mmHg). Anti-hypertensive, anti-hypertrophic and anti-fibrotic effects of N-methylated peptides and cocktail was further reflected by the decreased levels of circulating Ang II and increased ANP levels in sera of hypertensive rats along with decrease in collagen deposition in heart and kidney. Though, ACE inhibition is adequate to reduce SBP, targeting NEP and APN along with ACE is beneficial in tackling hypertension and associated fibrosis of heart.

Age-dependent differences in pulmonary host responses in ARDS: a prospective observational cohort study

Background

Results from preclinical studies suggest that age-dependent differences in host defense and the pulmonary renin–angiotensin system (RAS) are responsible for observed differences in epidemiology of acute respiratory distress syndrome (ARDS) between children and adults. The present study compares biomarkers of host defense and RAS in bronchoalveolar lavage (BAL) fluid from neonates, children, adults, and older adults with ARDS.

Methods

In this prospective observational study, we enrolled mechanical ventilated ARDS patients categorized into four age groups: 20 neonates (< 28 days corrected postnatal age), 29 children (28 days–18 years), 26 adults (18–65 years), and 17 older adults (> 65 years of age). All patients underwent a nondirected BAL within 72 h after intubation. Activities of the two main enzymes of RAS, angiotensin converting enzyme (ACE) and ACE2, and levels of biomarkers of inflammation, endothelial activation, and epithelial damage were determined in BAL fluid.

Results

Levels of myeloperoxidase, interleukin (IL)-6, IL-10, and p-selectin were higher with increasing age, whereas intercellular adhesion molecule-1 was higher in neonates. No differences in activity of ACE and ACE2 were seen between the four age groups.

Conclusions

Age-dependent differences in the levels of biomarkers in lungs of ARDS patients are present. Especially, higher levels of markers involved in the neutrophil response were found with increasing age. In contrast to preclinical studies, age is not associated with changes in the pulmonary RAS.

Electronic supplementary material

The online version of this article (10.1186/s13613-019-0529-4) contains supplementary material, which is available to authorized users.

Exposure to diisononyl phthalate induced an increase in blood pressure through activation of the ACE/ AT1R axis and inhibition of NO production

Recent epidemiological studies have found that diisononyl phthalate (DINP) is associated with an increase in blood pressure. However, this correlation had not been clarified, nor has the underlying mechanism been characterized. In this study, C57/BL6 mice were exposed to DINP doses of 0.15 mg/kg/day, 1.5 mg/kg/day or 15 mg/kg/day for 6 weeks. Dexamethasone (DEXA) was used to build the hypertension model. After DINP exposure and 1 mg/kg/day DEXA treatment, the levels of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP) and heart rate (HR) were determined, and any histopathological changes in hypertension targeted organs of the mice were investigated. The results suggest that DINP exposure and DEXA treatment induced marked increases in SBP, DBP, and MBP, and that 15 mg/kg/day DINP exposure could also increase the HR level. Along with the blood pressure increase, DINP exposure induced pathological changes to the heart, aorta, and kidney. To explore the underlying mechanism, we measured the expression of angiotensin converting enzyme (ACE), angiotensin-II type 1 receptor (AT1R) and endothelial nitric oxide synthase (eNOS) in the aorta, as well as the nitric oxide (NO) concentration in serum. The data suggest that DINP exposure and DEXA treatment enhance the expression of ACE and AT1R, and inhibit eNOS expression and NO production. Interestingly, treatment with 5 mg/kg/day ACE inhibitor (ACEI) alleviated the increase in blood pressure induced by DINP exposure and DEXA treatment. These findings expand our understanding of how DINP exposure impacts the development of hypertension, and elucidates the underlying mechanisms.

Active-site directed peptide l-Phe-d-His-l-Leu inhibits angiotensin converting enzyme activity and dexamethasone-induced hypertension in rats

Hypertension is the fundamental cause of cardiovascular and cerebrovascular disorders. Several natural and synthetic peptides are being used as antihypertensive agents, which target angiotensin converting enzyme (ACE), the master regulator of angiotensin (Ang) II production. In this study, we have evaluated ACE-inhibitory potential of the tripeptide l-Phenylalanyl-d-Histidyl-l-Leucine (l-Phe-d-His-l-Leu) in vitro and its antihypertensive effect in rat model of dexamethasone-induced hypertension. l-Phe-d-His-l-Leu was custom-designed by changing the configuration of penultimate amino acid residue (histidine) from C-terminal of Ang I, the site at which ACE acts upon and generates Ang II. l-Phe-d-His-l-Leu effectively inhibited ACE activity in a dose-dependent and competitive manner with an IC₅₀ of 53.32 ± 0.13 nmol/L. Both fluorescence spectra and circular dichroism data revealed the direct interaction between l-Phe-d-His-l-Leu and ACE. In addition, molecular docking studies revealed the strong interaction of l-Phe-d-His-l-Leu with the critical active site amino acid residues of ACE. Further, the administration of l-Phe-d-His-l-Leu resulted in decrease in blood pressure (142 ± 3 mmHg) compared to dexamethasone alone group (167 ± 2 mmHg). Besides, l-Phe-d-His-l-Leu decreased the levels of circulating Ang II, and reduced fibrosis in heart and kidney, as evidenced by decreases in collagen deposition. Thus, the strategy of incorporation of d-amino acids in ACE-inhibitory peptides could be valuable in the development of antihypertensive drugs.