New Mechanisms to Prevent Heart Failure with Preserved Ejection Fraction Using Glucagon-like Peptide-1 Receptor Agonism (GLP-1 RA) in Metabolic Syndrome and in Type 2 Diabetes: A Review

This review examines the impact of obesity on the pathophysiology of heart failure with preserved ejection fraction (HFpEF) and focuses on novel mechanisms for HFpEF prevention using a glucagon-like peptide-1 receptor agonism (GLP-1 RA). Obesity can lead to HFpEF through various mechanisms, including low-grade systemic inflammation, adipocyte dysfunction, accumulation of visceral adipose tissue, and increased pericardial/epicardial adipose tissue (contributing to an increase in myocardial fat content and interstitial fibrosis). Glucagon-like peptide 1 (GLP-1) is an incretin hormone that is released from the enteroendocrine L-cells in the gut. GLP-1 reduces blood glucose levels by stimulating insulin synthesis, suppressing islet α-cell function, and promoting the proliferation and differentiation of β-cells. GLP-1 regulates gastric emptying and appetite, and GLP-1 RA is currently indicated for treating type 2 diabetes (T2D), obesity, and metabolic syndrome (MS). Recent evidence indicates that GLP-1 RA may play a significant role in preventing HFpEF in patients with obesity, MS, or obese T2D. This effect may be due to activating cardioprotective mechanisms (the endogenous counter-regulatory renin angiotensin system and the AMPK/mTOR pathway) and by inhibiting deleterious remodeling mechanisms (the PKA/RhoA/ROCK pathway, aldosterone levels, and microinflammation). However, there is still a need for further research to validate the impact of these mechanisms on humans.

Human Soluble Prorenin Receptor Expressed in Adipose Tissue Improves Insulin Sensitivity and Endothelial Function in Obese Female Mice

Increased circulating levels of the soluble prorenin receptor (sPRR), a component of the renin angiotensin system (RAS), plays a role in obesity, glucose, and insulin homeostasis. However, elevated plasma sPRR in diabetic patients has been shown correlated with hyperglycemia in women but not men. Hence, the current study sought to understand the contribution of human sPRR (HsPRR) produced in the adipose tissue (Adi) on adipogenesis, and glucose and insulin balance in obesity settings. Adi-HsPRR mice were generated by breeding human sPRR-Myc-tag transgenic mice with mice expressing Adiponectin/Cre. The mouse model was validated by detecting 28kDa myc-tagged HsPRR by western blotting. Adipose HsPRR expression did not change circulating sPRR in female mice fed a standard chow diet or high fat diet (HFD) but increased plasma sPRR in male Adi-HsPRR mice fed a HFD compared to HFD-fed controls. Yet, Adi-HsPRR improved insulin sensitivity, vascular relaxation and the vasodilator agent Ang 1-7 in obese female mice but not in the male counterparts. Moreover, Adi-HsPRR expression reduced the expression of the adipogenic genes SREBP1C and CD36 only in gonadal white adipose from obese female mice, signifying that adipose tissue-derived HsPRR exerts a sex-specific effect on insulin sensitivity and endothelial function which seems independent of circulating sPRR.

Studying the Roles of the Renin-Angiotensin System in Accelerating the Disease of High-Fat-Diet-Induced Diabetic Nephropathy in a db/db and ACE2 Double-Gene-Knockout Mouse Model

Diabetic nephropathy (DN) is a crucial metabolic health problem. The renin-angiotensin system (RAS) is well known to play an important role in DN. Abnormal RAS activity can cause the over-accumulation of angiotensin II (Ang II). Angiotensin-converting enzyme inhibitor (ACEI) administration has been proposed as a therapy, but previous studies have also indicated that chymase, the enzyme that hydrolyzes angiotensin I to Ang II in an ACE-independent pathway, may play an important role in the progression of DN. Therefore, this study established a model of severe DN progression in a db/db and ACE2 KO mouse model (db and ACE2 double-gene-knockout mice) to explore the roles of RAS factors in DNA and changes in their activity after short-term (only 4 weeks) feeding of a high-fat diet (HFD) to 8-week-old mice. The results indicate that FD-fed db/db and ACE2 KO mice fed an HFD represent a good model for investigating the role of RAS in DN. An HFD promotes the activation of MAPK, including p-JNK and p-p38, as well as the RAS signaling pathway, leading to renal damage in mice. Blocking Ang II/AT1R could alleviate the progression of DN after administration of ACEI or chymase inhibitor (CI). Both ACE and chymase are highly involved in Ang II generation in HFD-induced DN; therefore, ACEI and CI are potential treatments for DN.

Optimal Conservative Therapy Use among Adult Cure Glomerulonephropathy Participants with IgA Nephropathy

Optimal supportive therapy with BP and proteinuria control is pivotal in treating patients with IgA nephropathy. Suboptimal treatment of hypertension and proteinuria persisted in many patients with IgA nephropathy in the Cure Glomerulonephropathy Network study. Many patients had above-target proteinuria despite optimal BP control and may benefit from novel therapies or clinical trials.

Neuroprotective association of preoperative renin-angiotensin system blocking agents use in patients undergoing carotid interventions

OBJECTIVE

The optimal medical management strategy in the periprocedural period for patients undergoing carotid artery interventions is not well described. Renin-angiotensin-system blocking (RASB) agents are considered to be among the first line anti-hypertensive agents; however, their role in the perioperative period is unclear. The objective of this study was to examine the relationship between the use of RASB agents on periprocedural outcomes in patients undergoing carotid interventions-carotid endarterectomy (CEA), transfemoral carotid artery stenting (CAS), and transcervical carotid artery revascularization (TCAR).

METHOD

The Society for Vascular Surgery Quality Initiative database was queried for all patients undergoing CAS, CEA, and TCAR between 2003 and 2020. Patients were stratified into two groups based upon their use of RASB agents in the periprocedural period. The primary endpoint was periprocedural neurologic events (including both strokes and transient ischemic attacks (TIAs)). The secondary endpoints were peri-procedural mortality and significant cardiac events, including myocardial infarction, dysrhythmia, and congestive heart failure.

RESULTS

Over 150,000 patients were included in the analysis: 13,666 patients underwent TCAR, 13,811 underwent CAS, and 125,429 underwent CEA for carotid artery stenosis. Overall, 52.2% of patients were maintained on RASB agents. Among patients undergoing CEA, patients on RASB agents had a significantly lower rate of periprocedural neurologic events (1.7% versus 2.0%, p =0.001). The peri-procedural neurological event rate in the TCAR cohort was similarly reduced in those treated with RASB agents, but did not reach statistical significance (2.0% vs 2.4%, p = 0.162). Among patients undergoing CAS, there was no difference in perioperative neurologic events between the RASB treated and untreated cohorts (3.4% vs 3.2%, p = 0.234); however, the use of RASB agents was significantly associated with lower mortality (1.2% vs 1.7%, p =0.001) with CAS. The use of preoperative RAS-blocking agents did not appear to affect the overall rates of adverse cardiac events with any of the three carotid intervention types, or periprocedural mortality following CEA or TCAR. On multivariable analysis, the use of RAS-blocking agents was independently associated with lower rates of post-procedural neurologic events in patients undergoing CEA (OR 0.819, CI 0.747-0.898; p = 0.01) and TCAR (OR 0.869, CI 0.768-0.984; p = 0.026), but not in those undergoing CAS (OR 0.967, CI 0.884-1.057; p = 0.461).

CONCLUSION

The use of peri-procedural RASB agents was associated with a significantly decreased rate of neurologic events in patients undergoing both CEA and TCAR. This effect was not observed in patients undergoing CAS. As carotid interventions warrant absolute minimization of perioperative complications in order to provide maximum efficacy with regard to stroke protection, the potential neuro-protective effect associated with RASB agents use following CEA and TCAR warrants further examination.

Association of angiotensin II and receptors in peri-implantation endometrium with microvessel density and pregnancy outcomes of women with recurrent implantation failure after embryo transfer

Purpose

Investigate whether local angiotensin II (AngII) and its AngII type 1 and 2 receptors (AT1R, AT2R) in the endometrium are different and correlate with microvessel density in women with reproductive failure and pregnancy outcomes.

Methods

Endometrium during the window of implantation from 40 women with recurrent miscarriage (RM) and 40 with recurrent implantation failure (RIF) were compared with 27 fertile women. Peri-implantation endometrium from 54 women prior to euploid embryo transfer were collected and compared in women with successful pregnancy and unsuccessful pregnancy.

Results

Compared with fertile women, expression of AT2R was significantly lower, while AT1R/AT2R expression ratio was significantly higher in the stroma of the RIF group. Endometrium arteriole MVD was significantly lower and negatively correlated with the AT1R/AT2R expression ratio in the stroma of the RIF group. No significant differences and correlations were found in the RM group. Compared with the pregnancy group, expression of AT1R and AT2R were significantly lower in all compartments, but only AT1R/AT2R ratio was significantly higher in the stroma of the non-pregnancy group. Similarly, endometrium arteriole MVD was also significantly lower and negatively correlated with the AT1R/AT2R ratio in the stroma of the non-pregnancy group.

Conclusion

Local renin-angiotensin system is dysregulated in peri-implantation endometrium and associated with abnormal angiogenesis in RIF and poor implantation outcome after embryo transfer.

Biological sex differences in renin angiotensin system enzymes ACE and ACE2 regulate normal tissue response to radiation injury

Introduction: In experimental animal models, biological sex-differences in the manifestation and severity of normal tissue radiation injury have been well-documented. Previously we demonstrated male and female rats have differential and highly reproducible responses to high-dose partial body irradiation (PBI) with male rats having greater susceptibility to both gastrointestinal acute radiation syndrome (GI-ARS) and radiation pneumonitis than female rats. Methods: In the current study, we have investigated whether differential expression of the renin-angiotensin system (RAS) enzymes angiotensin converting enzyme (ACE) and ACE2 contribute to the observed sex-related differences in radiation response. Results: During the period of symptomatic pneumonitis, the relative ratio of ACE to ACE2 (ACE/ACE2) protein in the whole lung was significantly increased by radiation in male rats alone. Systemic treatment with small molecule ACE2 agonist diminazene aceturate (DIZE) increased lung ACE2 activity and reduced morbidity during radiation pneumonitis in both sexes. Notably DIZE treatment also abrogated morbidity in male rats during GI-ARS. We then evaluated the contribution of the irradiated bone marrow (BM) compartment on lung immune cell infiltration and ACE imbalance during pneumonitis. Transplantation of bone marrow from irradiated donors increased both ACE-expressing myeloid cell infiltration and immune ACE activity in the lung during pneumonitis compared to non-irradiated donors. Discussion: Together, these data demonstrate radiation induces a sex-dependent imbalance in the renin-angiotensin system enzymes ACE and ACE2. Additionally, these data suggest a role for ACE-expressing myeloid cells in the pathogenesis of radiation pneumonitis. Finally, the observed sex-differences underscore the need for consideration of sex as a biological variable in the development of medical countermeasures for radiation exposure.

Identifying the patient with heart failure to be treated with vericiguat

The pathophysiology of heart failure with reduced ejection fraction (HFrEF) is a complex process in which a number of neurohormonal systems are involved. Targeting only some of these systems, but not all, translates into a partial benefit of HF treatment. The nitric oxide-soluble guanylate cyclase (sGC)-cGMP pathway is impaired in HF, leading to cardiac, vascular and renal disturbances. Vericiguat is a once-daily oral stimulator of sGC that restores this system. No other disease-modifying HF drugs act on this system. Despite guidelines recommendations, a substantial proportion of patients are not taking all recommended drugs or when taking them, they do so at low doses, limiting their potential benefits. In this context, treatment should be optimized considering different parameters, such as blood pressure, heart rate, renal function, or potassium, as they may interfere with their implementation at the recommended doses. The VICTORIA trial showed that adding vericiguat to standard therapy in patients with HFrEF significantly reduced the risk of cardiovascular death or HF hospitalization by 10% (NNT 24). Furthermore, vericiguat does not interfere with heart rate, renal function or potassium, making it particularly useful for improving the prognosis of patients with HFrEF in specific settings and clinical profiles.

Deciphering mechanisms of action of ACE inhibitors in neurodegeneration using Drosophila models of Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disorder for which there is no cure. Recently, several studies have reported a significant reduction in the incidence and progression of dementia among some patients receiving antihypertensive medications such as angiotensin-converting enzyme inhibitors (ACE-Is) and angiotensin receptor blockers (ARBs). Why these drugs are beneficial in some AD patients and not others is unclear although it has been shown to be independent of their role in regulating blood pressure. Given the enormous and immediate potential of ACE-Is and ARBs for AD therapeutics it is imperative that we understand how they function. Recently, studies have shown that ACE-Is and ARBs, which target the renin angiotensin system in mammals, are also effective in suppressing neuronal cell death and memory defects in Drosophila models of AD despite the fact that this pathway is not conserved in flies. This suggests that the beneficial effects of these drugs may be mediated by distinct and as yet, identified mechanisms. Here, we discuss how the short lifespan and ease of genetic manipulations available in Drosophila provide us with a unique and unparalleled opportunity to rapidly identify the targets of ACE-Is and ARBs and evaluate their therapeutic effectiveness in robust models of AD.

Parboiled Germinated Brown Rice Improves Cardiac Structure and Gene Expression in Hypertensive Rats

Hypertension leads to oxidative stress, inflammation, and fibrosis. The suppression of these indicators may be one treatment approach. Parboiled germinated brown rice (PGBR), obtained by steaming germinated Jasmine rice, reduces oxidative stress and inflammation in vivo. PGBR contains more bioactive compounds than brown rice (BR) and white rice (WR). Anti-hypertensive benefits of PGBR have been predicted, but research is lacking. The anti-hypertensive effects of PGBR were investigated in the downstream gene network of hypertension pathogenesis, including the renin-angiotensin system, fibrosis, oxidative stress production, and antioxidant enzymes in N-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive rats. To strengthen our findings, the cardiac structure was also studied. PGBR-exposed rats showed significant reductions in systolic blood pressure (SBP) compared to the hypertensive group. WR did not reduce SBP because of the loss of bioactive compounds during intensive milling. PGBR also reduced the expression of the angiotensin type 1 receptor (AT1R), transforming growth factor-β (TGF-β), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX4), which contribute to the renin-angiotensin system, fibrosis, and oxidative stress production, respectively. Losartan (Los, an anti-hypertensive drug)-treated rats also exhibited similar gene expression, implying that PGBR may reduce hypertension using the same downstream target as Los. Our data also indicated that PGBR reduced cardiac lesions, such as the cardiomyopathy induced by L-NAME. This is the first report on the anti-hypertensive effects of PGBR in vivo by the suppression of the renin response, fibrosis, and improved cardiac structure.

Blood pressure effects of sodium transport along the distal nephron

The mammalian distal nephron is a target of highly effective antihypertensive drugs. Genetic variants that alter its transport activity are also inherited causes of high or low blood pressure, clearly establishing its central role in human blood pressure regulation. Much has been learned during the past 25 years about salt transport along this nephron segment, spurred by the cloning of major transport proteins and the discovery of disease-causing genetic variants. Recognition is increasing that substantial cellular and segmental heterogeneity is present along this segment, with electroneutral sodium transport dominating more proximal segments and electrogenic sodium transport dominating more distal segments. Coupled with recent insights into factors that modulate transport along these segments, we now understand one important mechanism by which dietary potassium intake influences sodium excretion and blood pressure. This finding has solved the aldosterone paradox, by demonstrating how aldosterone can be both kaliuretic, when plasma potassium is elevated, and anti-natriuretic, when extracellular fluid volume is low. However, what also has become clear is that aldosterone itself only stimulates a portion of the mineralocorticoid receptors along this segment, with the others being activated by glucocorticoid hormones instead. These recent insights provide an increasingly clear picture of how this short nephron segment contributes to blood pressure homeostasis and have important implications for hypertension prevention and treatment.

Effect of renin-angiotensin system antihypertensive medication use on cognitive function in diabetes mellitus with obesity or overweight: An ancillary study to the Action for Health in Diabetes (Look AHEAD) trial

AIM

To determine whether antihypertensive medication (AHM) acting through the renin angiotensin system (RAS-AHM), compared with other AHM, can mitigate effects on cognitive function and risk for impairment in a population with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

This secondary analysis of the randomized controlled Action for Health in Diabetes (Look AHEAD) study included 712 community-dwelling participants who were followed over 15 years. Logistic regression was used to relate RAS-AHM use to cognitive impairment, and linear regression was used to relate RAS-AHM use to domain-specific cognitive function after adjusting for potential confounders.

RESULTS

A total of 563 individuals reported RAS-AHM use and 149 reported other-AHM use during the study. RAS-AHM users have college or higher education (53%), had higher baseline glycated haemoglobin (57 mmol/mol), and reported higher diabetes medication use (86%), while other-AHM users were more likely to be White (72%), obese (25%) and to have cardiovascular history (19%). RAS-AHM use was not associated with a reduced risk of dementia compared with other-AHM use. We did observe better executive function (Trail Making Test, part B, P < 0.04), processing speed (Digit Symbol Substitution Test, P < 0.004), verbal memory (Rey Auditory Verbal Learning Test-delayed recall, P < 0.005), and composite score (P < 0.008) among RAS-AHM users compared with other-AHM users.

CONCLUSION

In this sample of adults with T2DM, free of dementia at baseline, we observed a slower decline in processing speed, executive function, verbal memory, and composite score among RAS-AHM users.

What do we know about the renin angiotensin system and inflammatory bowel disease?

INTRODUCTION

The renin-angiotensin system (RAS) is an important homeostatic pathway, with emerging evidence for the impact of its components on inflammation and fibrosis in gastrointestinal tissues. This review aims to review current knowledge of the physiological mechanism of RAS in inflammatory bowel disease (IBD), and potential therapeutic implications.

AREAS COVERED

An extensive online literature review including Pubmed, Medline, and Google Scholar was undertaken. Discussion on the components of the RAS, localization, and physiological functions in the gastrointestinal tract, preclinical, and clinical data in IBD, and the relation with SARS-Cov-2 are covered in this review.

EXPERT OPINION

RAS inhibition may have a role as anti-fibrotic adjunct therapy. Targeting the local gastrointestinal RAS with novel modes of delivery may be a target for future therapeutics for IBD, given the widespread availability and safety of current options as utilized in other diseases. Further insight into the mechanism and downstream effects of gastrointestinal ACE2 may lead to a better understanding of the pathogenesis of IBD.

Plasma Angiotensin Converting Enzyme 2 (ACE2) Activity in Healthy Controls and Patients with Cardiovascular Risk Factors and/or Disease

Angiotensin converting enzyme 2 (ACE2) is an endogenous negative regulator of the renin-angiotensin system, a key factor in the development of cardiovascular disease (CVD). ACE2 is also used by SARS-CoV-2 for host cell entry. Given that COVID-19 is associated with hypercoagulability, it is timely to explore the potential relationship between plasma ACE2 activity and the coagulation profile. In this cross-sectional study, ACE2 activity and global coagulation assays (GCA) including thromboelastography, thrombin, and fibrin generation were measured in adult healthy controls (n = 123; mean age 41 ± 17 years; 35% male) and in patients with cardiovascular risk factors and/or disease (n = 258; mean age 65 ± 14 years; 55% male). ACE2 activity was significantly lower in controls compared to patients with cardiovascular risk factors and/or disease (median 0.10 (0.02, 3.33) vs. 5.99 (1.95, 10.37) pmol/mL/min, p < 0.001). Of the healthy controls, 48% had undetectable ACE2 activity. Controls with detectable ACE2 had lower maximum amplitude (p < 0.001). In patients with cardiovascular risk factors and/or disease, those in the 3rd tertile were older and male (p = 0.002), with a higher Framingham grade and increased number of cardiovascular risk factors (p < 0.001). In conclusion, plasma ACE2 activity is undetectable to very low in young healthy controls with minimal clinically relevant associations to GCA. Patients with cardiovascular risk factors and/or disease have increased plasma ACE2 activity, suggesting that it may be an important biomarker of endothelial dysfunction and atherosclerosis.

Soluble ACE2 Is Filtered into the Urine

Background

ACE2 is a key enzyme in the renin-angiotensin system (RAS) capable of balancing the RAS by metabolizing angiotensin II (AngII). First described in cardiac tissue, abundance of ACE2 is highest in the kidney, and it is also expressed in several extrarenal tissues. Previously, we reported an association between enhanced susceptibility to hypertension and elevated renal AngII levels in global ACE2-knockout mice.

Methods

To examine the effect of ACE2 expressed in the kidney, relative to extrarenal expression, on the development of hypertension, we used a kidney crosstransplantation strategy with ACE2-KO and WT mice. In this model, both native kidneys are removed and renal function is provided entirely by the transplanted kidney, such that four experimental groups with restricted ACE2 expression are generated: WT→WT (WT), KO→WT (KidneyKO), WT→KO (SystemicKO), and KO→KO (TotalKO). Additionally, we used nanoscale mass spectrometry-based proteomics to identify ACE2 fragments in early glomerular filtrate of mice.

Results

Although significant differences in BP were not detected, a major finding of our study is that shed or soluble ACE2 (sACE2) was present in urine of KidneyKO mice that lack renal ACE2 expression. Detection of sACE2 in the urine of KidneyKO mice during AngII-mediated hypertension suggests that sACE2 originating from extrarenal tissues can reach the kidney and be excreted in urine. To confirm glomerular filtration of ACE2, we used micropuncture and nanoscale proteomics to detect peptides derived from ACE2 in the Bowman's space.

Conclusions

Our findings suggest that both systemic and renal tissues may contribute to sACE2 in urine, identifying the kidney as a major site for ACE2 actions. Moreover, filtration of sACE2 into the lumen of the nephron may contribute to the pathophysiology of kidney diseases characterized by disruption of the glomerular filtration barrier.

Inhibition of the angiotensin II type 2 receptor AT(2)R is a novel therapeutic strategy for glioblastoma

Glioblastoma (GBM) is an aggressive malignant primary brain tumor with limited therapeutic options. We show that the angiotensin II (AngII) type 2 receptor (AT₂R) is a therapeutic target for GBM and that AngII, endogenously produced in GBM cells, promotes proliferation through AT₂R. We repurposed EMA401, an AT₂R antagonist originally developed as a peripherally restricted analgesic, for GBM and showed that it inhibits the proliferation of AT₂R-expressing GBM spheroids and blocks their invasiveness and angiogenic capacity. The crystal structure of AT₂R bound to EMA401 was determined and revealed the receptor to be in an active-like conformation with helix-VIII blocking G-protein or β-arrestin recruitment. The architecture and interactions of EMA401 in AT₂R differ drastically from complexes of AT₂R with other relevant compounds. To enhance central nervous system (CNS) penetration of EMA401, we exploited the crystal structure to design an angiopep-2-tethered EMA401 derivative, A3E. A3E exhibited enhanced CNS penetration, leading to reduced tumor volume, inhibition of proliferation, and increased levels of apoptosis in an orthotopic xenograft model of GBM.

Short-Term Changes in Serum Potassium and the Risk of Subsequent Vascular Events and Mortality: Results from a Randomized Controlled Trial of ACE Inhibitors

BACKGROUND AND OBJECTIVES

Hyperkalemia after starting renin-angiotensin system inhibitors has been shown to be subsequently associated with a higher risk of cardiovascular and kidney outcomes. However, whether to continue or discontinue the drug after hyperkalemia remains unclear.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data came from the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial, which included a run-in period where all participants initiated angiotensin-converting enzyme inhibitor-based therapy (a fixed combination of perindopril and indapamide). The study population was taken as patients with type 2 diabetes with normokalemia (serum potassium of 3.5 to <5.0 mEq/L) at the start of run-in. Potassium was remeasured 3 weeks later when a total of 9694 participants were classified into hyperkalemia (≥5.0 mEq/L), normokalemia, and hypokalemia (<3.5 mEq/L) groups. After run-in, patients were randomized to continuation of the angiotensin-converting enzyme inhibitor-based therapy or placebo; major macrovascular, microvascular, and mortality outcomes were analyzed using Cox regression during the following 4.4 years (median).

RESULTS

During active run-in, 556 (6%) participants experienced hyperkalemia. During follow-up, 1505 participants experienced the primary composite outcome of major macrovascular and microvascular events. Randomized treatment of angiotensin-converting enzyme inhibitor-based therapy significantly decreased the risk of the primary outcome (38.1 versus 42.0 per 1000 person-years; hazard ratio, 0.91; 95% confidence interval, 0.83 to 1.00; P=0.04) compared with placebo. The magnitude of effects did not differ across subgroups defined by short-term changes in serum potassium during run-in (P for heterogeneity =0.66). Similar consistent treatment effects were also observed for all-cause death, cardiovascular death, major coronary events, major cerebrovascular events, and new or worsening nephropathy (P for heterogeneity ≥0.27).

CONCLUSIONS

Continuation of angiotensin-converting enzyme inhibitor-based therapy consistently decreased the subsequent risk of clinical outcomes, including cardiovascular and kidney outcomes and death, regardless of short-term changes in serum potassium.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE), NCT00145925.

Use of renin angiotensin aldosterone system inhibitors in children with lupus and time to glucocorticoid discontinuation

There is little data to inform use of renin angiotensin aldosterone system (RAAS) inhibitors in pediatric patients with systemic lupus erythematosus (SLE). Here, we sought to characterize RAAS inhibitor use in pediatric SLE, and determine whether early RAAS inhibitor initiation among children with incident lupus nephritis is associated with decreased duration of chronic glucocorticoid exposure. A retrospective cohort study was performed of children (ages 5-18) with SLE and/or lupus nephritis in the Truven MarketScan^ΤΜ Medicaid and Commercial databases (2013-2018) and estimated RAAS inhibitor use. Among incident nephritis cases, we used competing risk hazard models with inverse probability of treatment weighting to estimate the association between RAAS inhibitor initiation less than 180 days after diagnosis and time to glucocorticoid discontinuation with kidney failure as a competing event. Among 592 children with nephritis and 1407 children with non-kidney SLE, 67% and 15% ever received RAAS inhibitors, respectively. Median duration of RAAS inhibitor use among 323 incident users was 14 and 9 months in children with and without nephritis, respectively. Medicaid enrollment was independently associated with greater likelihood of RAAS inhibitor use, irrespective of nephritis. Among 158 incident nephritis cases, early RAAS inhibitor initiation was significantly associated with a faster rate of glucocorticoid discontinuation (adjusted sub-distribution hazard ratio 1.81, 95% confidence interval [1.09 - 3.00]). Thus, early initiation of RAAS inhibitors may have a role in children newly diagnosed with lupus nephritis; not only those with refractory proteinuria after induction therapy. Hence, integrated health systems data could be leveraged to confirm these findings and optimize adjunctive therapies in pediatric lupus.

Renin-angiotensin system modulation through enalapril and/or exercise training improves visceral adiposity in obese mice

INTRODUCTION

Obesity-related metabolic diseases occur as a result of disruptions in white adipose tissue (WAT) plasticity, especially through visceral fat accumulation and adipocyte hypertrophy. This study aimed to evaluate the impact of renin-angiotensin system (RAS) and bradykinin receptors modulation by enalapril treatment and/or exercise training on WAT morphology and related deleterious outcomes.

METHODS

Male C57BL/6 mice were fed either a standard chow or a high-fat (HF) diet for 16 weeks. At the 8th week, HF-fed animals were divided into sedentary (HF), enalapril treatment (HF-E), exercise training (HF-T), and enalapril treatment plus exercise training (HF-ET) groups. Following the experimental protocol, body mass gain, adiposity index, insulin resistance, visceral WAT morphometry, renin-angiotensin system, and bradykinin receptors were evaluated.

RESULTS

The HF group displayed increased adiposity, larger visceral fat mass, and adipocyte hypertrophy, which was accompanied by insulin resistance, overactivation of Ang II/AT1R arm, and favoring of B1R in bradykinin receptors profile. All interventions ameliorated visceral adiposity and related outcomes by favoring the Ang 1-7/MasR arm and the B2R expression in B1R/B2R ratio. However, combined therapy additively reduced Ang II/Ang 1-7 ratio.

CONCLUSION

Our results suggest that Ang 1-7/MasR arm and B2R activation might be relevant targets in the treatment of visceral obesity.

Systems analysis shows that thermodynamic physiological and pharmacological fundamentals drive COVID-19 and response to treatment

Why a systems analysis view of this pandemic? The current pandemic has inflicted almost unimaginable grief, sorrow, loss, and terror at a global scale. One of the great ironies with the COVID‐19 pandemic, particularly early on, is counter intuitive. The speed at which specialized basic and clinical sciences described the details of the damage to humans in COVID‐19 disease has been impressive. Equally, the development of vaccines in an amazingly short time interval has been extraordinary. However, what has been less well understood has been the fundamental elements that underpin the progression of COVID‐19 in an individual and in populations. We have used systems analysis approaches with human physiology and pharmacology to explore the fundamental underpinnings of COVID‐19 disease. Pharmacology powerfully captures the thermodynamic characteristics of molecular binding with an exogenous entity such as a virus and its consequences on the living processes well described by human physiology. Thus, we have documented the passage of SARS‐CoV‐2 from infection of a single cell to species jump, to tropism, variant emergence and widespread population infection. During the course of this review, the recurrent observation was the efficiency and simplicity of one critical function of this virus. The lethality of SARS‐CoV‐2 is due primarily to its ability to possess and use a variable surface for binding to a specific human target with high affinity. This binding liberates Gibbs free energy (GFE) such that it satisfies the criteria for thermodynamic spontaneity. Its binding is the prelude to human host cellular entry and replication by the appropriation of host cell constituent molecules that have been produced with a prior energy investment by the host cell. It is also a binding that permits viral tropism to lead to high levels of distribution across populations with newly formed virions. This thermodynamic spontaneity is repeated endlessly as infection of a single host cell spreads to bystander cells, to tissues, to humans in close proximity and then to global populations. The principal antagonism of this process comes from SARS‐CoV‐2 itself, with its relentless changing of its viral surface configuration, associated with the inevitable emergence of variants better configured to resist immune sequestration and importantly with a greater affinity for the host target and higher infectivity. The great value of this physiological and pharmacological perspective is that it reveals the fundamental thermodynamic underpinnings of SARS‐CoV‐2 infection.

Current options for slowing the progression of chronic kidney disease

From a certain stage, chronic kidney disease progresses to terminal kidney failure that requires renal replacement therapy with dialysis or transplantation. The progression can be significantly slowed by blocking the renin angiotensin aldosterone system (RAAS) with angiotensin converting enzyme (ACE) inhibitors or angiotensin II type 1 receptor blockers (ARB). Another new option to enhance the effect of blocking the RAAS system is the use of sodium glucose cotransporter 2 (SGLT2) inhibitors, or gliflozins. Dapagliflozin is currently available and reimbursed for patients with both diabetic and non-diabetic kidney disease. In the near future, treatment with the mineralocorticoid receptor inhibitor finerenone should be made available that significantly potentiates the effect of ACE or ARB inhibitors. Recent data show that it is possible to influence the progression of renal insufficiency with exercise.

Moderate Intensity Aerobic Exercise Potential Favorable Effect Against COVID-19: The Role of Renin-Angiotensin System and Immunomodulatory Effects

The coronavirus disease (COVID-19) pandemic is caused by a novel coronavirus (CoV) named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As the angiotensin converting enzyme 2 (ACE2) is the cellular receptor of SARS-CoV-2, it has a strong interaction with the renin angiotensin system (RAS). Experimental studies have shown that the higher levels of ACE2 or increasing ACE2/ACE1 ratio improve COVID-19 outcomes through lowering inflammation and death. Aerobic moderate intensity physical exercise fights off infections by two mechanisms, the inhibition of ACE/Ang II/AT1-R pathway and the stimulation of ACE2/Ang-(1-7)/MasR axis. Exercise can also activate the anti-inflammatory response so that it can be a potential therapeutic strategy against COVID-19. Here, we summarize and focus the relation among COVID-19, RAS, and immune system and describe the potential effect of aerobic moderate intensity physical exercise against CoV as a useful complementary tool for providing immune protection against SARS-CoV-2 virus infection, which is a novel intervention that requires further investigation.

Soluble angiotensin-converting enzyme 2 is transiently elevated in COVID-19 and correlates with specific inflammatory and endothelial markers

The main entry receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is angiotensin-converting enzyme 2 (ACE2). SARS-CoV-2 interactions with ACE2 may increase ectodomain shedding but consequences for the renin-angiotensin system and pathology in Coronavirus disease 2019 (COVID-19) remain unclear. We measured soluble ACE2 (sACE2) and sACE levels by enzyme-linked immunosorbent assay in 114 hospital-treated COVID-19 patients compared with 10 healthy controls; follow-up samples after four months were analyzed for 58 patients. Associations between sACE2 respectively sACE and risk factors for severe COVID-19, outcome, and inflammatory markers were investigated. Levels of sACE2 were higher in COVID-19 patients than in healthy controls, median 5.0 (interquartile range 2.8-11.8) ng/ml versus 1.4 (1.1-1.6) ng/ml, p < .0001. sACE2 was higher in men than women but was not affected by other risk factors for severe COVID-19. sACE2 decreased to 2.3 (1.6-3.9) ng/ml at follow-up, p < .0001, but remained higher than in healthy controls, p = .012. sACE was marginally lower during COVID-19 compared with at follow-up, 57 (45-70) ng/ml versus 72 (52-87) ng/ml, p = .008. Levels of sACE2 and sACE did not differ depending on survival or disease severity. sACE2 during COVID-19 correlated with von Willebrand factor, factor VIII and D-dimer, while sACE correlated with interleukin 6, tumor necrosis factor α, and plasminogen activator inhibitor 1. Conclusions: sACE2 was transiently elevated in COVID-19, likely due to increased shedding from infected cells. sACE2 and sACE during COVID-19 differed in correlations with markers of inflammation and endothelial dysfunction, suggesting release from different cell types and/or vascular beds.

The role of renin-angiotensin system in patients with left ventricular assist devices

End-stage heart failure is a condition in which the up-regulation of the systemic and local renin-angiotensin-aldosterone system (RAAS) leads to end-organ damage and is largely irreversible despite optimal medication. Left ventricular assist devices (LVADs) can downregulate RAAS activation by unloading the left ventricle and increasing the cardiac output translating into a better end-organ perfusion improving survival. However, the absence of pulsatility brought about by continuous-flow devices may variably trigger RAAS activation depending on left ventricular (LV) intrinsic contractility, the design and speed of the pump device. Moreover, the concept of myocardial recovery is being tested in clinical trials and in this setting LVAD support combined with intense RAAS inhibition can promote recovery and ensure maintenance of LV function after explantation. Blood pressure control on LVAD recipients is key to avoiding complications as gastrointestinal bleeding, pump thrombosis and stroke. Furthermore, emerging data highlight the role of RAAS antagonists as prevention of arteriovenous malformations that lead to gastrointestinal bleeds. Future studies should focus on the role of angiotensin receptor inhibitors in preventing myocardial fibrosis in patients with LVADs and examine in greater details the target blood pressure for these patients.

Telmisartan prevents high-fat diet-induced neurovascular impairments and reduces anxiety-like behavior

Angiotensin II receptor blockers (telmisartan) prevent rodents from diet-induced obesity and improve their metabolic status. Hyperglycemia and obesity are associated with reduced cerebral blood flow and neurovascular uncoupling which may lead to behavioral deficits. We wanted to know whether a treatment with telmisartan prevents these changes in obesity.We put young mice on high-fat diet and simultaneously treated them with telmisartan. At the end of treatment, we performed laser speckle imaging and magnetic resonance imaging to assess the effect on neurovascular coupling and cerebral blood flow. Different behavioral tests were used to investigate cognitive function.Mice developed diet-induced obesity and after 16, not 8 weeks of high-fat diet, however, the response to whisker pad stimulation was about 30% lower in obese compared to lean mice. Simultaneous telmisartan treatment increased the response again by 10% compared to obese mice. Moreover, telmisartan treatment normalized high-fat diet-induced reduction of cerebral blood flow and prevented a diet-induced anxiety-like behavior. In addition to that, telmisartan affects cellular senescence and string vessel formation in obesity.We conclude, that telmisartan protects against neurovascular unit impairments in a diet-induced obesity setting and may play a role in preventing obesity related cognitive deficits in Alzheimer's disease.

Is RAS the Link Between COVID-19 and Increased Stress in Head and Neck Cancer Patients?

The COVID-19 pandemic emerged as a largely unexplained outbreak of pneumonia cases, in Wuhan City, China and rapidly spread across the world. By 11th March 2020, WHO declared it as a global pandemic. The resulting restrictions, to contain its spread, demanded a momentous change in the lifestyle of the general population as well as cancer patients. This augmented negative effects on the mental health of patients with head and neck cancer (HNC), who already battle with the stress of cancer diagnosis and treatment. The causative agent of COVID-19, SARS-CoV2, gains entry through the Angiotensin converting enzyme 2 (ACE2) receptor, which is a component of the Renin Angiotensin System (RAS). RAS has been shown to influence cancer and stress such that it can have progressive and suppressive effects on both. This review provides an overview of SARS-CoV2, looks at how the RAS provides a mechanistic link between stress, cancer and COVID-19 and the probable activation of the RAS axis that increase stress (anxiogenic) and tumor progression (tumorigenic), when ACE2 is hijacked by SARS-CoV2. The mental health crises brought about by this pandemic have been highlighted in many studies. The emerging links between cancer and stress make it more important than ever before to assess the stress burden of cancer patients and expand the strategies for its management.

Renin-Angiotensin System Blockers and the Risk of COVID-19-Related Mortality in Patients with Kidney Failure

BACKGROUND AND OBJECTIVES

There is concern about potential deleterious effects of angiotensin-converting enzyme inhibitors (ACEis) and angiotensin II receptor blockers (ARBs) in patients with coronavirus disease 2019 (COVID-19). Patients with kidney failure, who often use ACEis/ARBs, are at higher risk of more severe COVID-19. However, there are no data available on the association of ACEi/ARB use with COVID-19 severity in this population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

From the European Renal Association COVID-19 database (ERACODA), we retrieved data on kidney transplant recipients and patients on dialysis who were affected by COVID-19, between February 1 and October 1, 2020, and had information on 28-day mortality. We used Cox proportional-hazards regression to calculate hazard ratios for the association between ACEi/ARB use and 28-day mortality risk. Additionally, we studied the association of discontinuation of these agents with 28-day mortality.

RESULTS

We evaluated 1511 patients: 459 kidney transplant recipients and 1052 patients on dialysis. At diagnosis of COVID-19, 189 (41%) of the transplant recipients and 288 (27%) of the patients on dialysis were on ACEis/ARBs. A total of 88 (19%) transplant recipients and 244 (23%) patients on dialysis died within 28 days of initial presentation. In both groups of patients, there was no association between ACEi/ARB use and 28-day mortality in both crude and adjusted models (in transplant recipients, adjusted hazard ratio, 1.12; 95% confidence interval [95% CI], 0.69 to 1.83; in patients on dialysis, adjusted hazard ratio, 1.04; 95% CI, 0.73 to 1.47). Among transplant recipients, ACEi/ARB discontinuation was associated with a higher mortality risk after adjustment for demographics and comorbidities, but the association was no longer statistically significant after adjustment for severity of COVID-19 (adjusted hazard ratio, 1.36; 95% CI, 0.40 to 4.58). Among patients on dialysis, ACEi/ARB discontinuation was not associated with mortality in any model. We obtained similar results across subgroups when ACEis and ARBs were studied separately, and when other outcomes for severity of COVID-19 were studied, e.g., hospital admission, admission to the intensive care unit, or need for ventilator support.

CONCLUSIONS

Among kidney transplant recipients and patients on dialysis with COVID-19, there was no significant association of ACEi/ARB use or discontinuation with mortality.

Association between early worsening of kidney function and poor outcomes in patients treated with renin angiotensin system inhibitors: A meta-analysis

AIM

As renin angiotensin system inhibitors (RASi) are widely used in the clinic, early worsening of kidney function (EWKF) after RASi therapy deserves attention, as its clinical significance is unknown. The aim was to evaluate the relationship between EWKF and long-term outcomes including all-cause mortality, kidney and cardiovascular events, in all the patients treated with RASi.

METHODS

We searched PubMed, Embase, and the Cochrane databases for controlled trials that compared the outcomes of patients with and without EWKF after RASi treatment. Our primary outcome was all-cause mortality, and secondary outcomes were kidney and cardiovascular events. We pooled data using a random effects model.

RESULTS

A total of ten studies were enrolled, of which eight were randomized trials (including 33 454 patients) and two were observational studies (including 148 144 patients). Of the eight randomized trials, 4996 patients with type 2 diabetes, 19 118 with heart failure (HF), and 9340 with atherosclerotic vascular disease and diabetes with end-organ damage. Both observational studies investigated all kinds of patients with initial RASi treatment. In patients with RASi, the EWKF group had a higher risk of all-cause mortality than the no-EWKF group in the randomized studies (n =  13 581; RR, 1.22; 95% CI, 1.04-1.42; P = .02) and in observational studies (n = 148 144; OR, 1.70; 95% CI, 1.43-2.01; P < .00001). In patients who experienced EWKF, no statistically significant difference was found between the efficacy of RASi and placebo in all-cause mortality (n = 1762; RR, 0.85; 95% CI, 0.68-1.06; P = .14).

CONCLUSION

RASi treatment led to an increased incidence of EWKF which was associated with poorer long-term outcomes. As the benefit of RAS blockade to patients with EWKF was limited, we suggest clinicians use RASi with caution when EWKF occurs.

Efficacy and Safety of Mineralocorticoid Receptor Antagonists in Kidney Failure Patients Treated with Dialysis: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Patients with kidney failure have a high risk of cardiovascular disease due to cardiac remodeling, left ventricular fibrosis, and hyperaldosteronism, all of which can be potentially mitigated by mineralocorticoid receptor antagonists. However, because of the fear of hyperkalemia, the use of mineralocorticoid receptor antagonists in patients with kidney failure is limited in current clinical practice, and few studies have investigated the efficacy and safety. Thus, we aimed to determine the benefits and side effects of mineralocorticoid receptor antagonists in patients with kidney failure treated with dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is a systematic review and meta-analysis of randomized controlled trials published from 2005 to 2020 that compared the effect of mineralocorticoid receptor antagonists with either placebo or no treatment in patients with kidney failure. Two reviewers independently searched the PubMed, EMBASE, and Cochrane databases for all published studies, extracted data, assessed the risk of bias, and rated the quality of evidence. A meta-analysis was conducted on 14 eligible randomized controlled trials, and a total of 1309 patients were included.

RESULTS

High-quality evidence suggested that mineralocorticoid receptor antagonists are associated with lower cardiovascular mortality (relative risk, 0.41; 95% confidence interval, 0.24 to 0.70; P=0.001) and all-cause mortality (relative risk, 0.44; 95% confidence interval, 0.30 to 0.66; P<0.001), and the risk of hyperkalemia was comparable with that of control group (relative risk, 1.12; 95% confidence interval, 0.91 to 1.36; P=0.29). However, no significant decrease in nonfatal cardiovascular events and stroke was observed, and there was no significant improvement in BP or cardiac performance parameters, including left ventricular ejection fraction and left ventricular mass index.

CONCLUSIONS

Our meta-analysis suggests that mineralocorticoid receptor antagonists might improve clinical outcomes of patients with kidney failure without significant increase in the risk of hyperkalemia.

COVID-19 and Hypertension: The What, the Why, and the How

It has been a year since the coronavirus disease 2019 (COVID-19) was declared pandemic and wreak havoc worldwide. Despite meticulous research has been done in this period, there are still much to be learn from this novel coronavirus. Globally, observational studies have seen that majority of the patients with COVID-19 have preexisting hypertension. This raises the question about the possible relationship between COVID-19 and hypertension. This review summarizes the current understanding of the link between hypertension and COVID-19 and its underlying mechanisms.

Renal Inflammation Induces Salt Sensitivity in Male db/db Mice through Dysregulation of ENaC

BACKGROUND

Hypertension is considered a major risk factor for the progression of diabetic kidney disease. Type 2 diabetes is associated with increased renal sodium reabsorption and salt-sensitive hypertension. Clinical studies show that men have higher risk than premenopausal women for the development of diabetic kidney disease. However, the renal mechanisms that predispose to salt sensitivity during diabetes and whether sexual dimorphism is associated with these mechanisms remains unknown.

METHODS

Female and male db/db mice exposed to a high-salt diet were used to analyze the progression of diabetic kidney disease and the development of hypertension.

RESULTS

Male, 34-week-old, db/db mice display hypertension when exposed to a 4-week high-salt treatment, whereas equivalently treated female db/db mice remain normotensive. Salt-sensitive hypertension in male mice was associated with no suppression of the epithelial sodium channel (ENaC) in response to a high-salt diet, despite downregulation of several components of the intrarenal renin-angiotensin system. Male db/db mice show higher levels of proinflammatory cytokines and more immune-cell infiltration in the kidney than do female db/db mice. Blocking inflammation, with either mycophenolate mofetil or by reducing IL-6 levels with a neutralizing anti-IL-6 antibody, prevented the development of salt sensitivity in male db/db mice.

CONCLUSIONS

The inflammatory response observed in male, but not in female, db/db mice induces salt-sensitive hypertension by impairing ENaC downregulation in response to high salt. These data provide a mechanistic explanation for the sexual dimorphism associated with the development of diabetic kidney disease and salt sensitivity.

Ramipril and Cardiovascular Outcomes in Patients on Maintenance Hemodialysis: The ARCADIA Multicenter Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

Renin-angiotensin system (RAS) inhibitors reduce cardiovascular morbidity and mortality in patients with CKD. We evaluated the cardioprotective effects of the angiotensin-converting enzyme inhibitor ramipril in patients on maintenance hemodialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this phase 3, prospective, randomized, open-label, blinded end point, parallel, multicenter trial, we recruited patients on maintenance hemodialysis with hypertension and/or left ventricular hypertrophy from 28 Italian centers. Between July 2009 and February 2014, 140 participants were randomized to ramipril (1.25-10 mg/d) and 129 participants were allocated to non-RAS inhibition therapy, both titrated up to the maximally tolerated dose to achieve predefined target BP values. The primary efficacy end point was a composite of cardiovascular death, myocardial infarction, or stroke. Secondary end points included the single components of the primary end point, new-onset or recurrence of atrial fibrillation, hospitalizations for symptomatic fluid overload, thrombosis or stenosis of the arteriovenous fistula, and changes in cardiac mass index. All outcomes were evaluated up to 42 months after randomization.

RESULTS

At comparable BP control, 23 participants on ramipril (16%) and 24 on non-RAS inhibitor therapy (19%) reached the primary composite end point (hazard ratio, 0.93; 95% confidence interval, 0.52 to 1.64; P=0.80). Ramipril reduced cardiac mass index at 1 year of follow-up (between-group difference in change from baseline: -16.3 g/m²; 95% confidence interval, -29.4 to -3.1), but did not significantly affect the other secondary outcomes. Hypotensive episodes were more frequent in participants allocated to ramipril than controls (41% versus 12%). Twenty participants on ramipril and nine controls developed cancer, including six gastrointestinal malignancies on ramipril (four were fatal), compared with none in controls.

CONCLUSIONS

Ramipril did not reduce the risk of major cardiovascular events in patients on maintenance hemodialysis.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

ARCADIA, NCT00985322 and European Union Drug Regulating Authorities Clinical Trials Database number 2008-003529-17.

Circulating Angiotensin-(1-7) Is Reduced in Alzheimer's Disease Patients and Correlates With White Matter Abnormalities: Results From a Pilot Study

Introduction

Alzheimer’s disease (AD) is the leading cause of dementia worldwide. Despite the extensive research, its pathophysiology remains largely unelucidated. Currently, more attention is being given to the disease’s vascular and inflammatory aspects. In this context, the renin-angiotensin system (RAS) emerges as a credible player in AD pathogenesis. The RAS has multiple physiological functions, conducted by its two opposing axes: the classical, led by Angiotensin II (Ang II), and the alternative, driven by Angiotensin-(1–7) [Ang-(1–7)]. These peptides were shown to interact with AD pathology in animal studies, but evidence from humans is scarce. Only 20 studies dosed RAS molecules in AD patients’ bloodstream, none of which assessed both axes simultaneously. Therefore, we conducted a cross-sectional, case-control exploratory study to compare plasma levels of Ang II and Ang-(1–7) in AD patients vs. age-matched controls. Within each group, we searched for correlations between RAS biomarkers and measures from magnetic resonance imaging (MRI).

Methods

We evaluated patients with AD (n = 14) and aged-matched controls (n = 14). Plasma Ang II and Ang-(1–7) were dosed using ELISA. Brain MRI was performed in a 3 Tesla scan, and a three-dimensional T1-weighted volumetric sequence was obtained. Images were then processed by FreeSurfer to calculate: (1) white matter hypointensities (WMH) volume; (2) volumes of hippocampus, medial temporal cortex, and precuneus. Statistical analyses used non-parametrical tests (Mann-Whitney and Spearman).

Results

Ang-(1–7) levels in plasma were significantly lower in the AD patients than in controls [median (25th–75th percentiles)]: AD [101.5 (62.43–126.4)] vs. controls [209.3 (72–419.1)], p = 0.014. There was no significant difference in circulating Ang II. In the AD patients, but not in controls, there was a positive and significant correlation between Ang-(1–7) values and WMH volumes (Spearman’s rho = 0.56, p = 0.038). Ang-(1–7) did not correlate with cortical volumes in AD or in controls. Ang II did not correlate with any MRI variable in none of the groups.

Conclusion

If confirmed, our results strengthen the hypothesis that RAS alternative axis is downregulated in AD, and points to a possible interaction between Ang-(1–7) and cerebrovascular lesions in AD.

The swedish covid-19 intensive care cohort: Risk factors of ICU admission and ICU mortality

BACKGROUND

Several studies have recently addressed factors associated with severe Coronavirus disease 2019 (COVID-19); however, some medications and comorbidities have yet to be evaluated in a large matched cohort. We therefore explored the role of relevant comorbidities and medications in relation to the risk of intensive care unit (ICU) admission and mortality.

METHODS

All ICU COVID-19 patients in Sweden until 27 May 2020 were matched to population controls on age and gender to assess the risk of ICU admission. Cases were identified, comorbidities and medications were retrieved from high-quality registries. Three conditional logistic regression models were used for risk of ICU admission and three Cox proportional hazards models for risk of ICU mortality, one with comorbidities, one with medications and finally with both models combined, respectively.

RESULTS

We included 1981 patients and 7924 controls. Hypertension, type 2 diabetes mellitus, chronic renal failure, asthma, obesity, being a solid organ transplant recipient and immunosuppressant medications were independent risk factors of ICU admission and oral anticoagulants were protective. Stroke, asthma, chronic obstructive pulmonary disease and treatment with renin-angiotensin-aldosterone inhibitors (RAASi) were independent risk factors of ICU mortality in the pre-specified primary analyses; treatment with statins was protective. However, after adjusting for the use of continuous renal replacement therapy, RAASi were no longer an independent risk factor.

CONCLUSION

In our cohort oral anticoagulants were protective of ICU admission and statins was protective of ICU death. Several comorbidities and ongoing RAASi treatment were independent risk factors of ICU admission and ICU mortality.

Angiotensin (1-7) Expressing Probiotic as a Potential Treatment for Dementia

Increasing life expectancies are unfortunately accompanied by increased prevalence of Alzheimer's disease (AD). Regrettably, there are no current therapeutic options capable of preventing or treating AD. We review here data indicating that AD is accompanied by gut dysbiosis and impaired renin angiotensin system (RAS) function. Therefore, we propose the potential utility of an intervention targeting both the gut microbiome and RAS as both are heavily involved in proper CNS function. One potential approach which our group is currently exploring is the use of genetically-modified probiotics (GMPs) to deliver therapeutic compounds. In this review, we specifically highlight the potential utility of utilizing a GMP to deliver Angiotensin (1-7), a beneficial component of the renin-angiotensin system with relevant functions in circulation as well as locally in the gut and brain.

Update on New Aspects of the Renin-Angiotensin System in Hepatic Fibrosis and Portal Hypertension: Implications for Novel Therapeutic Options

There is considerable experimental evidence that the renin angiotensin system (RAS) plays a central role in both hepatic fibrogenesis and portal hypertension. Angiotensin converting enzyme (ACE), a key enzyme of the classical RAS, converts angiotensin I (Ang I) to angiotensin II (Ang II), which acts via the Ang II type 1 receptor (AT1R) to stimulate hepatic fibrosis and increase intrahepatic vascular tone and portal pressure. Inhibitors of the classical RAS, drugs which are widely used in clinical practice in patients with hypertension, have been shown to inhibit liver fibrosis in animal models but their efficacy in human liver disease is yet to be tested in adequately powered clinical trials. Small trials in cirrhotic patients have demonstrated that these drugs may lower portal pressure but produce off-target complications such as systemic hypotension and renal failure. More recently, the alternate RAS, comprising its key enzyme, ACE2, the effector peptide angiotensin-(1–7) (Ang-(1–7)) which mediates its effects via the putative receptor Mas (MasR), has also been implicated in the pathogenesis of liver fibrosis and portal hypertension. This system is activated in both preclinical animal models and human chronic liver disease and it is now well established that the alternate RAS counter-regulates many of the deleterious effects of the ACE-dependent classical RAS. Work from our laboratory has demonstrated that liver-specific ACE2 overexpression reduces hepatic fibrosis and liver perfusion pressure without producing off-target effects. In addition, recent studies suggest that the blockers of the receptors of alternate RAS, such as the MasR and Mas related G protein-coupled receptor type-D (MrgD), increase splanchnic vascular resistance in cirrhotic animals, and thus drugs targeting the alternate RAS may be useful in the treatment of portal hypertension. This review outlines the role of the RAS in liver fibrosis and portal hypertension with a special emphasis on the possible new therapeutic approaches targeting the ACE2-driven alternate RAS.

Mechanism of herbal medicine on hypertensive nephropathy (Review)

Hypertensive nephropathy is the most common complication of hypertension, and is one of the main causes of end-stage renal disease (ESRD) in numerous countries. The basic pathological feature of hypertensive nephropathy is arteriolosclerosis followed by renal parenchymal damage. The etiology of this disease is complex, and its pathogenesis is mainly associated with renal hemodynamic changes and vascular remodeling. Despite the increased knowledge on the pathogenesis of hypertensive nephropathy, the current clinical treatment methods are still not effective in preventing the development of the disease to ESRD. Herbal medicine, which is used to relieve symptoms, can improve hypertensive nephropathy through multiple targets. Since there are few clinical studies on the treatment of hypertensive nephropathy with herbal medicine, this article aims to review the progress on the basic research on the treatment of hypertensive nephropathy with herbal medicine, including regulation of the renin angiotensin system, inhibition of sympathetic excitation, antioxidant stress and anti-inflammatory protection of endothelial cells, and improvement of obesity-associated factors. Herbal medicine with different components plays a synergistic and multi-target role in the treatment of hypertensive nephropathy. The description of the mechanism of herbal medicine in the treatment of hypertensive nephropathy will contribute towards the progress of modern medicine.

Mechanisms of Pulmonary Hypertension in Acute Respiratory Distress Syndrome (ARDS)

Background: Acute respiratory distress syndrome (ARDS) is a severe and often fatal disease. The causes that lead to ARDS are multiple and include inhalation of salt water, smoke particles, or as a result of damage caused by respiratory viruses. ARDS can also arise due to systemic complications such as blood transfusions, sepsis, or pancreatitis. Unfortunately, despite a high mortality rate of 40%, there are limited treatment options available for ARDS outside of last resort options such as mechanical ventilation and extracorporeal support strategies. Aim of review: A complication of ARDS is the development of pulmonary hypertension (PH); however, the mechanisms that lead to PH in ARDS are not fully understood. In this review, we summarize the known mechanisms that promote PH in ARDS. Key scientific concepts of review: (1) Provide an overview of acute respiratory distress syndrome; (2) delineate the mechanisms that contribute to the development of PH in ARDS; (3) address the implications of PH in the setting of coronavirus disease 2019 (COVID-19).

Prospective Cohort Study of Renin-Angiotensin System Blocker Usage after Hospitalized Acute Kidney Injury

BACKGROUND AND OBJECTIVES

The risk-benefit ratio of angiotensin-converting enzyme inhibitor or angiotensin receptor blocker therapy after AKI may be altered due to concerns regarding recurrent AKI. We evaluated, in a prospective cohort, the association between use (versus nonuse) of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and the subsequent risk of AKI and other adverse outcomes after hospitalizations with and without AKI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied 1538 patients recently discharged from the hospital who enrolled in the multicenter, prospective ASSESS-AKI study, with approximately half of patients experiencing AKI during the index hospitalization. All participants were seen at a baseline visit 3 months after their index hospitalization and were categorized at that time on whether they were using angiotensin-converting enzyme inhibitors/angiotensin receptor blockers or not. We used multivariable Cox regression, adjusting for demographics, comorbidities, eGFR, urine protein-creatinine ratio, and use of other medications, to examine the association between angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use and subsequent risks of AKI, death, kidney disease progression, and adjudicated heart-failure events.

RESULTS

The use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers was 50% (386/769) among those with AKI during the index hospitalization and 47% (362/769) among those without. Among those with AKI during the index hospitalization, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use was not associated with a higher risk of recurrent hospitalized AKI (adjusted hazard ratio, 0.88; 95% confidence interval, 0.69 to 1.13). Associations between angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use and death, kidney disease progression, and adjudicated heart-failure events appeared similar in study participants who did and did not experience AKI during the index hospitalization (all interaction P values >0.05).

CONCLUSIONS

The risk-benefit ratio of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker therapy after hospital discharge appears to be similar regardless of whether AKI occurred during the hospitalization.

Development of a novel AlphaLISA ImmunoAssay for Big angiotensin-25

We previously described the discovery of Big angiotensin-25 (Bang-25), an angiotensin-related peptide isolated from human urine. Bang-25 consists of the first 25 amino acids of the N-terminus of angiotensinogen (Aogen), with N-linked glycosylation on the 14th amino acid and a cysteine conjugated to the 18th amino acid. Bang-25 is rapidly converted into angiotensin II (Ang II) by chymase. Because Bang-25 is widely distributed in human tissues, including islet cells in the pancreas and podocytes in the kidney, we hypothesized that it may participate in the Ang II production system in these tissues. To test this hypothesis, we developed a specific assay for Bang-25 and used it to examine the urinary concentrations of Bang-25 in patients with diabetes mellitus (DM). The assay used the Amplified Luminescent Proximity Homogeneous Assay (Alpha)-based ELISA method (AlphaLISA) of PerkinElmer Japan and included antibodies specific to the N-terminus of Ang II and the C-terminus of Bang-25. The AlphaLISA ImmunoAssay specifically recognized Bang-25 and had no cross-reactivity with Aogen or Ang I. Bang-25 was detected in healthy volunteers' urine samples but not in their plasma samples. In patients with DM, the urinary Bang-25 concentration was significantly higher than in healthy volunteers. Moreover, the results indicated that the Bang-25 concentration in the urine may offer a different perspective on disease status from that provided by urinary albumin. This assay could provide a useful tool for determining urinary Bang-25, which may prove an important biomarker for diabetic kidney disease.

Regulation of ACE-2 enzyme by hyperoxia in lung epithelial cells by post-translational modification

BACKGROUND

Bronchopulmonary Dysplasia (BPD) occurs in premature neonates with respiratory distress who require supplemental oxygen in the first days after birth. BPD involves uniform arrest of alveolar development and variable interstitial cellularity and/or fibroproliferation. Previous studies by our lab showed that the enzyme, angiotensin converting enzyme-2 (ACE-2) and its product Ang1-7 exerting action on the receptor Mas oncogene in what is known as ACE-2/Mas axis is protective to lung cells. We also showed that ACE-2 is expressed in fetal human lung fibroblasts but is significantly decreased by hyperoxic gas lung injury, an effect caused by ACE-2 enzyme shedding mediated by TNF-alpha-converting enzyme (TACE/ADAM17). However, no reports yet exist about the regulation of ACE-2 in the alveolar epithelia in hyperoxic lung injury.

OBJECTIVE

In this study we aim to define the effects of hyperoxic lung injury on the protective ACE-2 enzyme in the human lung alveolar epithelial cell line A549.

DESIGN/METHODS

Cultured A549 cells were exposed to hyperoxia (95% O2) or normoxia (21% O2) for 3 or 7 days in serum-free nutrient media. Cells were lysed and culture media were collected to test for cellular ACE-2 enzymatic activity and for ACE-2, Mas receptor, TACE/ADAM17, and ubiquitin proteins abundance by immunoblotting. Cells were harvested in Trizol for RNA extraction and ACE-2 qRT-PCR. Whole cell extracts of A549 cell line was used for ACE-2 immunoprecipitation and subsequent ubiquitin immunoblotting.

RESULTS

Total ubiquitinated proteins were increased by hyperoxia treatment, while ACE-2 and Mas receptor proteins abundance and ACE-2 enzymatic activity were decreased significantly in A549 cells exposed to hyperoxia relative to the normoxia controls. The percent decrease in ACE-2 activity corresponded with increased time of hyperoxic gas exposure. However, in contrast to our data from lung fibroblasts, no significant change was noted in ACE-2 protein released into the media or in ACE-2 mRNA levels by the hyperoxic treatment. Ubiquitin immunoreactive bands were detectable in the ACE-2 immunoprecipitate.

CONCLUSIONS

These data suggest that hyperoxic exposure of the lung epithelial cells decreases the protective enzyme ACE-2 by cell type specific mechanisms independent of shedding by TACE/ADAM17. The data also suggest a regulatory level of ACE-2 downstream of transcription may involve ACE-2 ubiquitination and targeting for degradation.

Angiotensin Converting Enzyme-2 (ACE-2) role in disease and future in research

Coronavirus Disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Like the 2002-2003 epidemic severe acute respiratory syndrome coronavirus (SARS-CoV), angiotensin converting enzyme-2 (ACE-2) has been identified as the SARS-CoV-2 receptor.^1-3 The virus docks into host cell via its spike protein binding to ACE-2 and undergoes proteolytic cleavage by TMPRSS2 protease to facilitate membrane fusion. The spike protein binding to ACE-2 has been shown to be stronger in the novel SARS-CoV-2 virus.¹ This review will present an overview of ACE-2 biology.

Blockade of Renin Angiotensin System Ameliorates the Cardiac Arrhythmias and Sympathetic Neural Remodeling in Hearts of Type 2 DM Rat Model

OBJECTIVE

The present study was designed to investigate the effects of renin angiotensin system (RAS) blockade on cardiac arrhythmias and sympathetic nerve remodelling in heart tissues of type 2 diabetic rats.

METHODS

Thirty-two male Sprague Dawley rats were randomly allocated into 4 equal groups; a) normal control group: normal rats, b) DM group; after type 2 diabetes induction, rats received 2ml oral saline daily for 4 weeks, c) DM+ ACEi: after type 2 diabetes induction, rats were treated with enalapril (10 mg/kg, orally for 4 weeks) and d) DM+ ARBs: after type 2 diabetes induction, rats were treated with losartan (30 mg/kg, orally for 4 weeks).

RESULTS

In type 2 diabetic rats, the results demonstrated significant prolongation in Q-T interval and elevation of blood sugar, HOMA-IR index, TC, TGs, LDL, serum CK-MB, myocardial damage, myocardial MDA, myocardial norepinephrine and tyrosine hydroxylase (TH) density with significant reduction in serum HDL, serum insulin and myocardial GSH and CAT. On the other hand, blockade of RAS at the level of either ACE by enalapril or angiotensin (Ag) receptors by losartan resulted in significant improvement in ECG parameters (Q-T), cardiac enzymes (CK-MB), cardiac morphology, myocardial oxidative stress (low MDA, high CAT and GSH) and myocardial TH density.

CONCLUSION

RAS plays a role in the cardiac sympathetic nerve sprouting and cardiac arrhythmias induced by type 2 DM and its blockade might have a cardioprotective effect via attenuation of sympathetic nerve fibres remodelling, myocardial norepinephrine contents and oxidative stress.

The Effect of Local Renin Angiotensin System in the Common Types of Cancer

The Renin Angiotensin System (RAS) is a hormonal system that is responsible for blood pressure hemostasis and electrolyte balance. It is implicated in cancer hallmarks because it is expressed locally in almost all of the body's tissues. In this review, current knowledge on the effect of local RAS in the common types of cancer such as breast, lung, liver, prostate and skin cancer is summarised. The mechanisms by which RAS components could increase or decrease cancer activity are also discussed. In addition to the former, this review explores how the administration of AT1R blockers and ACE inhibitors drugs intervene with cancer therapy and contribute to the outcomes of cancer.

Role of the Renin-Angiotensin-Aldosterone System in Dystrophin-Deficient Cardiomyopathy

Dystrophin-deficient cardiomyopathy (DDC) is currently the leading cause of death in patients with dystrophinopathies. Targeting myocardial fibrosis (MF) has become a major therapeutic goal in order to prevent the occurrence of DDC. We aimed to review and summarize the current evidence about the role of the renin-angiotensin-aldosterone system (RAAS) in the development and perpetuation of MF in DCC. We conducted a comprehensive search of peer-reviewed English literature on PubMed about this subject. We found increasing preclinical evidence from studies in animal models during the last 20 years pointing out a central role of RAAS in the development of MF in DDC. Local tissue RAAS acts directly mainly through its main fibrotic component angiotensin II (ANG2) and its transducer receptor (AT1R) and downstream TGF-b pathway. Additionally, it modulates the actions of most of the remaining pro-fibrotic factors involved in DDC. Despite limited clinical evidence, RAAS blockade constitutes the most studied, available and promising therapeutic strategy against MF and DDC. Conclusion: Based on the evidence reviewed, it would be recommendable to start RAAS blockade therapy through angiotensin converter enzyme inhibitors (ACEI) or AT1R blockers (ARBs) alone or in combination with mineralocorticoid receptor antagonists (MRa) at the youngest age after the diagnosis of dystrophinopathies, in order to delay the occurrence or slow the progression of MF, even before the detection of any cardiovascular alteration.

High affinity binding of SARS-CoV-2 spike protein enhances ACE2 carboxypeptidase activity

The novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) has emerged to a pandemic and caused global public health crisis. Human angiotensin-converting enzyme 2(ACE2) was identified as the entry receptor for SARS-CoV-2. As a carboxypeptidase, ACE2 cleaves many biological substrates besides angiotensin II to control vasodilatation and vascular permeability. Given the nanomolar high affinity between ACE2 and SARS-CoV-2 spike protein, we investigated how this interaction would affect the enzymatic activity of ACE2. Surprisingly, SARS-CoV-2 trimeric spike protein increased ACE2 proteolytic activity ∼3-10 fold against model peptide substrates, such as caspase-1 substrate and Bradykinin-analog. The enhancement in ACE2 enzymatic function was mediated by the binding of SARS-CoV-2 spike RBD domain. These results highlighted the potential for SARS-CoV-2 infection to enhance ACE2 activity, which may be relevant to the cardiovascular symptoms associated with COVID-19.

Angiotensin-(1-7) Expressed From Lactobacillus Bacteria Protect Diabetic Retina in Mice

Purpose

A multitude of animal studies substantiates the beneficial effects of Ang-(1–7), a peptide hormone in the protective axis of the renin angiotensin system, in diabetes and its associated complications including diabetic retinopathy (DR). However, the clinical application of Ang-(1–7) is limited due to unfavorable pharmacological properties. As emerging evidence implicates gut dysbiosis in pathogenesis of diabetes and supports beneficial effects of probiotics, we sought to develop probiotics-based expression and delivery system to enhance Ang-(1–7) and evaluate the efficacy of engineered probiotics expressing Ang-(1–7) in attenuation of DR in animal models.

Methods

Ang-(1–7) was expressed in the Lactobacillus species as a secreted fusion protein with a trans-epithelial carrier to allow uptake into circulation. To evaluate the effects of Ang-(1–7) expressed from Lactobacillus paracasei (LP), adult diabetic eNOS^−/− and Akita mice were orally gavaged with either 1 × 10⁹ CFU of LP secreting Ang-(1–7) (LP-A), LP alone or vehicle, 3 times/week, for 8 and 12 weeks, respectively.

Results

Ang-(1–7) is efficiently expressed from different Lactobacillus species and secreted into circulation in mice fed with LP-A. Oral administration of LP-A significantly reduced diabetes-induced loss of retinal vascular capillaries. LP-A treatment also prevented loss of retinal ganglion cells, and significantly decreased retinal inflammatory cytokine expression in both diabetic eNOS^−/− and Akita mice.

Conclusions

These results provide proof-of-concept for feasibility and efficacy of using engineered probiotic species as live vector for delivery of Ang-(1–7) with enhanced bioavailability.

Translational Relevance

Probiotics-based delivery of Ang-(1–7) may hold important therapeutic potential for the treatment of DR and other diabetic complications.