Differential renal effects of candesartan at high and ultra-high doses in diabetic mice-potential role of the ACE2/AT2R/Mas axis

Telmisartan ameliorates nephropathy and restores the hippo pathway in rats with metabolic syndrome

The main objective of this study was to determine if the telmisartan-ameliorative effects of metabolic syndrome (MetS)-evoked nephropathy are attributed to the Hippo pathway. A secondary objective was to investigate the potential of vitamin D3 to enhance telmisartan-favourable effects. A diet composed of 24% fat and 3% salt, along with drinking water containing 10% fructose, was administered for 12 weeks to induce MetS. MetS-rats were given telmisartan (5 mg/kg/day), vitamin D3 (10 μg/kg/day) or both by gavage, starting in the sixth week of experimental diet administration. Assessments performed at closure included renal function, histological examination, catalase, malondialdehyde (MDA), nuclear factor kappa-B (NF-κB), interleukin-6 (IL-6), peroxisome proliferator-activated receptor-γ (PPAR-γ), phosphatase and tensin homolog (PTEN), and transforming growth factor-β (TGF-β). Matrix metalloproteinase-9 (MMP-9) immunostaining was conducted. The expression of the Hippo pathway components, as well as that of angiotensin II type 1 and type 2 (AT1 and AT2), receptors was evaluated. Telmisartan attenuated MetS-evoked nephropathy, as demonstrated by improvement of renal function and histological features, enhancement of catalase, reduction of MDA, inflammation (NF-κB, IL-6), and renal fibrosis (increased PPAR-γ and PTEN and reduced MMP-9 and TGF-β). Telmisartan downregulated AT1-receptor, upregulated AT2-receptor and restored the Hippo pathway. Vitamin D3 replicated most of the telmisartan-elicited effects and enhanced the antifibrotic actions of telmisartan. The alleviative effects of telmisartan on MetS-evoked nephropathy may be related to the restoration of the Hippo pathway. The combination of vitamin D3 and telmisartan exerted more favourable effects on metabolic and nephropathic biomarkers compared with either one administered alone.

Angiotensin II involvement in the development and persistence of amphetamine-induced sensitization: Striatal dopamine reuptake implications

Amphetamine (AMPH) exposure induces behavioural and neurochemical sensitization observed in rodents as hyperlocomotion and increased dopamine release in response to a subsequent dose. Brain Angiotensin II modulates dopaminergic neurotransmission through its AT1 receptors (AT1-R), positively regulating striatal dopamine synthesis and release. This work aims to evaluate the AT1-R role in the development and maintenance of AMPH-induced sensitization. Also, the AT1-R involvement in striatal dopamine reuptake was analysed. The sensitization protocol consisted of daily AMPH administration for 5 days and tested 21 days after withdrawal. An AT1-R antagonist, candesartan, was administered before or after AMPH exposure to evaluate the participation of AT1-R in the development and maintenance of sensitization, respectively. Sensitization was evaluated by locomotor activity and c-Fos immunostaining. Changes in dopamine reuptake kinetics were evaluated 1 day after AT1-R blockade withdrawal treatment, with or without the addition of AMPH in vitro. The social interaction test was performed as another behavioural output. Repeated AMPH exposure induced behavioural and neurochemical sensitization, which was prevented and reversed by candesartan. The AT1-R blockade increased the dopamine reuptake kinetics. Neither the AMPH administration nor the AT1-R blockade altered the performance of social interaction. Our results highlight the AT1-R's crucial role in AMPH sensitization. The enhancement of dopamine reuptake kinetics induced by the AT1-R blockade might attenuate the neuroadaptive changes that lead to AMPH sensitization and its self-perpetuation. Therefore, AT1-R is a prominent candidate as a target for pharmacological treatment of pathologies related to dopamine imbalance, including drug addiction and schizophrenia.

Adaptive and maladaptive roles of different angiotensin receptors in the development of cardiac hypertrophy and heart failure

Angiotensin II (Ang II) is formed by the action of angiotensin-converting enzyme (ACE) in the renin-angiotensin system. This hormone is known to induce cardiac hypertrophy and heart failure and its actions are mediated by the interaction of both pro- and antihypertrophic Ang II receptors (AT1R and AT2R). Ang II is also metabolized by ACE 2 to Ang-(1-7), which elicits the activation of Mas receptors (MasR) for inducing antihypertrophic actions. Since heart failure under different pathophysiological situations is preceded by adaptive and maladaptive cardiac hypertrophy, we have reviewed the existing literature to gain some information regarding the roles of AT1R, AT2R, and MasR in both acute and chronic conditions of cardiac hypertrophy. It appears that the activation of AT1R may be involved in the development of adaptive and maladaptive cardiac hypertrophy as well as subsequent heart failure because both ACE inhibitors and AT1R antagonists exert beneficial effects. On the other hand, the activation of both AT2R and MasR may prevent the occurrence of maladaptive cardiac hypertrophy and delay the progression of heart failure, and thus therapy with different activators of these antihypertrophic receptors under chronic pathological stages may prove beneficial. Accordingly, it is suggested that a great deal of effort should be made to develop appropriate activators of both AT2R and MasR for the treatment of heart failure subjects.

Effect of olmesartan and amlodipine on serum angiotensin-(1-7) levels and kidney and vascular function in patients with type 2 diabetes and hypertension

BACKGROUND

Recent studies suggest that angiotensin-converting enzyme 2 (ACE2) and angiotensin-(1-7) [Ang-(1-7)] might have beneficial effects on the cardiovascular system. We investigated the effects of olmesartan on the changes in serum ACE2 and Ang-(1-7) levels as well as kidney and vascular function in patients with type 2 diabetes and hypertension.

METHODS

This was a prospective, randomized, active comparator-controlled trial. Eighty participants with type 2 diabetes and hypertension were randomized to receive 20 mg of olmesartan (N = 40) or 5 mg of amlodipine (N = 40) once daily. The primary endpoint was changes of serum Ang-(1-7) from baseline to week 24.

RESULTS

Both olmesartan and amlodipine treatment for 24 weeks decreased systolic and diastolic blood pressures significantly by > 18 mmHg and > 8 mmHg, respectively. Serum Ang-(1-7) levels were more significantly increased by olmesartan treatment (25.8 ± 34.5 pg/mL → 46.2 ± 59.4 pg/mL) than by amlodipine treatment (29.2 ± 38.9 pg/mL → 31.7 ± 26.0 pg/mL), resulting in significant between-group differences (P = 0.01). Serum ACE2 levels showed a similar pattern (6.31 ± 0.42 ng/mL → 6.74 ± 0.39 ng/mL by olmesartan treatment vs. 6.43 ± 0.23 ng/mL → 6.61 ± 0.42 ng/mL by amlodipine treatment; P < 0.05). The reduction in albuminuria was significantly associated with the increases in ACE2 and Ang-(1-7) levels (r =  - 0.252 and r =  - 0.299, respectively). The change in Ang-(1-7) levels was positively associated with improved microvascular function (r = 0.241, P < 0.05). Multivariate regression analyses showed that increases in serum Ang-(1-7) levels were an independent predictor of a reduction in albuminuria.

CONCLUSIONS

These findings suggest that the beneficial effects of olmesartan on albuminuria may be mediated by increased ACE2 and Ang-(1-7) levels. These novel biomarkers may be therapeutic targets for the prevention and treatment of diabetic kidney disease.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05189015.

Targeting inflammation for the treatment of Diabetic Kidney Disease: a five-compartment mechanistic model

Diabetic kidney disease (DKD) is the leading cause of kidney failure worldwide. Mortality and morbidity associated with DKD are increasing with the global prevalence of type 2 diabetes. Chronic, sub-clinical, non-resolving inflammation contributes to the pathophysiology of renal and cardiovascular disease associated with diabetes. Inflammatory biomarkers correlate with poor renal outcomes and mortality in patients with DKD. Targeting chronic inflammation may therefore offer a route to novel therapeutics for DKD. However, the DKD patient population is highly heterogeneous, with varying etiology, presentation and disease progression. This heterogeneity is a challenge for clinical trials of novel anti-inflammatory therapies. Here, we present a conceptual model of how chronic inflammation affects kidney function in five compartments: immune cell recruitment and activation; filtration; resorption and secretion; extracellular matrix regulation; and perfusion. We believe that the rigorous alignment of pathophysiological insights, appropriate animal models and pathology-specific biomarkers may facilitate a mechanism-based shift from recruiting ‘all comers’ with DKD to stratification of patients based on the principal compartments of inflammatory disease activity.

Recent advances in developing small-molecule inhibitors against SARS-CoV-2

The COVID-19 pandemic caused by the novel SARS-CoV-2 virus has caused havoc across the entire world. Even though several COVID-19 vaccines are currently in distribution worldwide, with others in the pipeline, treatment modalities lag behind. Accordingly, researchers have been working hard to understand the nature of the virus, its mutant strains, and the pathogenesis of the disease in order to uncover possible drug targets and effective therapeutic agents. As the research continues, we now know the genome structure, epidemiological and clinical features, and pathogenic mechanism of SARS-CoV-2. Here, we summarized the potential therapeutic targets involved in the life cycle of the virus. On the basis of these targets, small-molecule prophylactic and therapeutic agents have been or are being developed for prevention and treatment of SARS-CoV-2 infection.

Angiotensin-Converting Enzyme Inhibitor and Angiotensin Receptor Blocker Use Associated with Reduced Mortality and Other Disease Outcomes in US Veterans with COVID-19

Objective

To determine the association between angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) use and coronavirus disease 2019 (COVID-19) severity and outcomes in US veterans.

Patients and Methods

We retrospectively examined 27,556 adult US veterans who tested positive for COVID-19 between March to November 2020. Logistic regression and Cox proportional hazards models using propensity score (PS) for weight, adjustment, and matching were used to examine the odds of an event within 60 days following a COVID-19–positive case date and time to death, respectively, according to ACEI and/or ARB prescription within 6 months prior to the COVID-19–positive case date.

Results

The overlap PS weighted logistic regression model showed lower odds of an intensive care unit (ICU) admission (odds ratio [OR] 95% CI 0.77, 0.61–0.98) and death within 60 days (0.87, 0.79–0.97) with an ACEI or ARB prescription. Veterans with an ARB-only prescription also had lower odds of an ICU admission (0.64, 0.44–0.92). The overlap PS weighted model similarly showed a lower risk of time to all-cause mortality in veterans with an ACEI or ARB prescription (HR [95% CI]: 0.87, 0.79–0.97) and an ARB only prescription (0.78, 0.67–0.91). Veterans with an ACEI prescription had higher odds of experiencing a septic event within 60 days after the COVID-19–positive case date (1.22, 1.02–1.46).

Conclusion

In this study of a national cohort of US veterans, we found that the use of an ACEI/ARB in patients with COVID-19 was not associated with increased mortality and other worse outcomes. Future studies should examine underlying pathways and further confirm the relationship of ACEI prescription with sepsis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40265-021-01639-2.

Overexpression of angiotensin-converting enzyme 2 by renin-angiotensin system inhibitors. Truth or myth? A systematic review of animal studies

Angiotensin-converting enzyme 2 (ACE2) protects against organ damage in hypertension and cardiovascular diseases by counter regulating the renin-angiotensin system (RAS). ACE2 is also the receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Based on the claim that RAS inhibitors (RASIs) cause ACE2 overexpression in some animal experiments, concerns have arisen that RASIs may aggravate SARS-CoV-2 infection and coronavirus disease-2019 severity in RASI-treated patients. To achieve a comprehensive review, a systematic search of MEDLINE/PubMed was conducted regarding the effects of RASIs on tissue ACE2 mRNA/protein expression in healthy animals and animal models of human diseases. We identified 88 eligible articles involving 168 experiments in the heart, kidneys, lungs, and other organs. Three of 38 experiments involving healthy animals showed ACE2 expression greater than twice that of the control (overexpression). Among 102 disease models (130 experiments), baseline ACE2 was overexpressed in 16 models (18 experiments) and less than half the control level (repression) in 28 models (40 experiments). In 72 experiments, RASIs did not change ACE2 levels from the baseline levels of disease models. RASIs caused ACE2 overexpression compared to control levels in seven experiments, some of which were unsupported by other experiments under similar conditions. In 36 experiments, RASIs reversed or prevented disease-induced ACE2 repression, yielding no or marginal changes. Therefore, ACE2 overexpression appears to be a rare rather than common consequence of RASI treatment in healthy animals and disease models. Future studies should clarify the pathophysiological significance of RASI-induced reversal or prevention of ACE2 repression in disease models.

Calcium channel blockers improve prognosis of patients with coronavirus disease 2019 and hypertension

BACKGROUND

Hypertension is considered an important risk factor for the coronavirus disease 2019 (COVID-19). The commonly anti-hypertensive drugs are the renin-angiotensin-aldosterone system (RAAS) inhibitors, calcium channel blockers (CCBs), and beta-blockers. The association between commonly used anti-hypertensive medications and the clinical outcome of COVID-19 patients with hypertension has not been well studied.

METHODS

We conducted a retrospective cohort study that included all patients admitted with COVID-19 to Huo Shen Shan Hospital and Guanggu District of the Maternal and Child Health Hospital of Hubei Province, Wuhan, China. Clinical and laboratory characteristics were extracted from electronic medical records. Hypertension and anti-hypertensive treatment were confirmed by medical history and clinical records. The primary clinical endpoint was all-cause mortality. Secondary endpoints included the rates of patients in common wards transferred to the intensive care unit and hospital stay duration. Logistic regression was used to explore the risk factors associated with mortality and prognosis. Propensity score matching was used to balance the confounders between different anti-hypertensive treatments. Kaplan-Meier curves were used to compare the cumulative recovery rate. Log-rank tests were performed to test for differences in Kaplan-Meier curves between different groups.

RESULTS

Among 4569 hospitalized patients with COVID-19, 31.7% (1449/4569) had a history of hypertension. There were significant differences in mortality rates between hypertensive patients with CCBs (7/359) and those without (21/359) (1.95% vs. 5.85%, risk ratio [RR]: 0.32, 95% confidence interval [CI]: 0.13-0.76, χ2 = 7.61, P = 0.0058). After matching for confounders, the mortality rates were similar between the RAAS inhibitor (4/236) and non-RAAS inhibitor (9/236) cohorts (1.69% vs. 3.81%, RR: 0.43, 95% CI: 0.13-1.43, χ2 = 1.98, P = 0.1596). Hypertensive patients with beta-blockers (13/340) showed no statistical difference in mortality compared with those without (11/340) (3.82% vs. 3.24%, RR: 1.19, 95% CI: 0.53-2.69, χ2 = 0.17, P = 0.6777).

CONCLUSIONS

In our study, we did not find any positive or negative effects of RAAS inhibitors or beta-blockers in COVID-19 patients with hypertension, while CCBs could improve prognosis.

Association of smoking and cardiovascular disease with disease progression in COVID-19: A systematic review and meta-analysis

The aim of this study was to systematically assess the association between smoking and cardiovascular disease (CVD) and disease progression among novel coronavirus pneumonia (coronavirus disease 2019 (COVID-19)) cases. PubMed database and Cochrane Library database were searched by computer to seek the epidemiological data of COVID-19 cases and literatures regarding CVDs from 1 Jan to 6 October 2020. Two researchers independently conducted literature screening, data collection and the assessment of the risk of bias of the studies included. RevMan 5.2 software was employed for meta-analysis. Funnel plot was adopted to assess the publication bias. On the whole, 21 studies comprising 7041 COVID-19 cases were included. As revealed from the meta-analysis, 14.0% (984/7027) of cases had a history of smoking, and 9.7% (675/6931) were subject to underlying CVDs. Cases with a history of smoking achieved a higher rate of COVID-19 disease progression as opposed to those having not smoked (OR 1.53, 95% CI 1.29–1.81, P < 0.00001), while no significant association could be found between smoking status and COVID-19 disease progression (OR 1.23, 95% CI 0.93–1.63, P = 0.15). Besides, smoking history elevated the mortality rate by 1.91-fold (OR 1.91, 95% CI 1.35–2.69, P = 0.0002). Moreover, underlying CVD elevated the incidence of severe disease by 2.87-fold (OR 2.87, 95% CI 2.29–3.61, P < 0.00001) and mortality by 3.05-fold (OR 3.05, 95% CI 1.82–5.11, P < 0.0001) in COVID-19 cases. As demonstrated from the current evidence, smoking displays a strong association with COVID-19 disease progression and mortality, and intensive tobacco control is imperative. Moreover, cases with CVD show a significantly elevated risk of disease progression and death when subject to COVID-19. However, the association between COVID-19 and CVD, and the potential effect exerted by smoking in the development of the two still require further verifications by larger and higher quality studies.

Amphetamine Induces Oxidative Stress, Glial Activation and Transient Angiogenesis in Prefrontal Cortex via AT1-R

Background: Amphetamine (AMPH) alters neurons, glia and microvessels, which affects neurovascular unit coupling, leading to disruption in brain functions such as attention and working memory. Oxidative stress plays a crucial role in these alterations. The angiotensin type I receptors (AT₁-R) mediate deleterious effects, such as oxidative/inflammatory responses, endothelial dysfunction, neuronal oxidative damage, alterations that overlap with those observed from AMPH exposure. Aims: The aim of this study was to evaluate the AT₁-R role in AMPH-induced oxidative stress and glial and vascular alterations in the prefrontal cortex (PFC). Furthermore, we aimed to evaluate the involvement of AT₁-R in the AMPH-induced short-term memory and working memory deficit. Methods: Male Wistar rats were repeatedly administered with the AT₁-R blocker candesartan (CAND) and AMPH. Acute oxidative stress in the PFC was evaluated immediately after the last AMPH administration by determining lipid and protein peroxidation. After 21 off-drug days, long-lasting alterations in the glia, microvessel architecture and to cognitive tasks were evaluated by GFAP, CD11b and von Willebrand immunostaining and by short-term and working memory assessment. Results: AMPH induced acute oxidative stress, long-lasting glial reactivity in the PFC and a working memory deficit that were prevented by AT₁-R blockade pretreatment. Moreover, AMPH induces transient angiogenesis in PFC via AT₁-R. AMPH did not affect short-term memory. Conclusion: Our results support the protective role of AT₁-R blockade in AMPH-induced oxidative stress, transient angiogenesis and long-lasting glial activation, preserving working memory performance.

A comprehensive guide to the pharmacologic regulation of angiotensin converting enzyme 2 (ACE2), the SARS-CoV-2 entry receptor

The recent emergence of coronavirus disease-2019 (COVID-19) as a global pandemic has prompted scientists to address an urgent need for defining mechanisms of disease pathology and treatment. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent for COVID-19, employs angiotensin converting enzyme 2 (ACE2) as its primary target for cell surface attachment and likely entry into the host cell. Thus, understanding factors that may regulate the expression and function of ACE2 in the healthy and diseased body is critical for clinical intervention. Over 66% of all adults in the United States are currently using a prescription drug and while earlier findings have focused on possible upregulation of ACE2 expression through the use of renin angiotensin system (RAS) inhibitors, mounting evidence suggests that various other widely administered drugs used in the treatment of hypertension, heart failure, diabetes mellitus, hyperlipidemias, coagulation disorders, and pulmonary disease may also present a varied risk for COVID-19. Specifically, we summarize mechanisms on how heparin, statins, steroids and phytochemicals, besides their established therapeutic effects, may also interfere with SARS-CoV-2 viral entry into cells. We also describe evidence on the effect of several vitamins, phytochemicals, and naturally occurring compounds on ACE2 expression and activity in various tissues and disease models. This comprehensive review aims to provide a timely compendium on the potential impact of commonly prescribed drugs and pharmacologically active compounds on COVID-19 pathology and risk through regulation of ACE2 and RAS signaling.

Angiotensin II Receptor Blockers but Not Angiotensin-Converting Enzyme Inhibitors Are Associated With a Reduced Risk of Acute Kidney Injury After Major Surgery

Objective: We investigated the respective effects of preoperative angiotensin-converting-enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) on the incidence of postoperative acute kidney injury (AKI) and mortality.

Methods: In this nested case-control study, we enrolled 20,276 patients who received major surgery. We collected their baseline demographic data, comorbidities and prescribed medication, the outcomes of postoperative AKI and mortality. AKI was defined by the criteria suggested by KDIGO (Kidney disease: Improving Global Outcome). Logistic regression was used to assess the impact of exposure to ACEIs or ARBs.

Results: Compared with patients without ACEI/ARB, patient who received ARBs had a significantly lower risk for postoperative AKI (adjusted odds ratio (OR) 0.82, p = 0.007). However, ACEI users had a higher risk for postoperative AKI than ARB users (OR 1.30, p = 0.027), whereas the risk for postoperative AKI was not significantly different between the ACEI users and patients without ACEI/ARB (OR 1.07, p = 0.49). Compared with patients without ACEI/ARB, both ACEI and ARB users were associated with a reduced risk of long-term all-cause mortality following surgery (OR 0.47, p = 0.002 and 0.60, p < 0.001 in ACEI and ARB users, respectively), without increasing the risk of hyperkalemia during the index hospitalization (p = 0.20). The risk of long-term all-cause mortality following surgery in ACEIs and ARBs users did not differ significantly (OR 0.74, p = 0.27). Furthermore, the higher the defined daily dose of ARB, the better the protection against AKI provided.

Conclusion: Our study revealed that preoperative use of ARBs was associated with reduced postoperative AKI, which is better in high quantity, whereas preoperative use of ACEIs or ARBs were both associated with reduced mortality and did not increase the risk of hyperkalemia.

Kidney-accumulating olmesartan-loaded nanomicelles ameliorate the organ damage in a murine model of Alport syndrome

ACE inhibitors or angiotensin II receptor blockers (ACEi/ARBs) have been a cornerstone of the management in kidney disease, but their use is often limited by undesired systemic effects, such as symptomatic hypotension. To minimize the extra-renal effects of ACEi/ARBs, we formulated hydrophobically modified glycol chitosan (HGC) nanomicelles releasing olmesartan (HGC-Olm) that specifically accumulated in the kidney, and investigated whether kidney-specific delivery of olmesartan by HGC nanomicelles could ameliorate organ damage in Col4a3^-/- mouse, a murine model of progressive chronic kidney disease mimicking human Alport syndrome. Ex vivo tracing demonstrated that intravenously injected HGC-Olm nanomicelles were specifically delivered to the kidney, with sustained release of olmesartan for more than 48 h. Contrary to the conventional delivery of olmesartan via oral route, injection of HGC-Olm nanomicelles did not alter blood pressure in Col4a3^-/- mice. Immunohistochemistry revealed that HGC nanomicelles were diffusely distributed from the cortex and glomeruli to the outer medulla, sparing the inner medulla. Phenotypic analysis showed that the attenuation of kidney fibrosis in the kidney of Col4a3^-/- mice by HGC-Olm nanomicelles was comparable to that noted with conventionally delivered olmesartan. Therefore, our results suggest that HGC-Olm nanomicelles could be a safe and effective alternative drug delivery system for kidney diseases.

Angiotensin-converting enzyme 2 and kidney diseases in the era of coronavirus disease 2019

In the decades since the discovery of angiotensin-converting enzyme 2 (ACE2), its protective role in terms of antagonizing activation of the classical renin-angiotensin system (RAS) axis has been recognized in clinical and experimental studies on kidney and cardiovascular diseases. The effects of ACE inhibitor/angiotensin type 1 receptor blockers (ACEi/ARBs) on ACE2-angiotensin-(1-7) (Ang- (1-7))-Mas receptor (MasR) axis activation has encouraged the use of such blockers in patients with kidney and cardiovascular diseases, until the emergence of coronavirus disease 2019 (COVID-19). The previously unchallenged functions of the ACE2-Ang-(1-7)-MasR axis and ACEi/ARBs are being re-evaluated in the era of COVID-19; the hypothesis is that ACEi/ARBs may increase the risk of severe acute respiratory syndrome coronavirus 2 infection by upregulating the human ACE2 receptor expression level. In this review, we examine ACE2 molecular structure, function (as an enzyme of the RAS), and distribution. We explore the roles played by ACE2 in kidney, cardiovascular, and pulmonary diseases, highlighting studies that defined the benefits imparted when ACEi/ARBs activated the local ACE2- Ang-(1-7)-MasR axis. Finally, the question of whether ACEi/ARBs therapies should be stopped in COVID-19-infected patients will be reviewed by reference to the available evidence.

Insights into the actions of angiotensin-1 receptor (AT1R) inverse agonists: Perspectives and implications in COVID-19 treatment

New coronavirus SARS-CoV-2 (COVID-19) has caused chaos in health care systems. Clinical manifestations of COVID-19 are variable, with a complex pathophysiology and as yet no specific treatment. It has been suggested that the renin-angiotensin-aldosterone system has a possible role in the severity of cases and the number of deaths. Our hypothesis is that drugs with inverse agonist effects to the angiotensin-1 receptor can be promising tools in the management of patients with COVID-19, possibly avoiding complications and the poor evolution in some cases. Any risk factors first need to be identified, and the most appropriate time to administer the drugs during the course of the infection also needs to be established. Several angiotensin receptor blockers (ARB) have a favorable profile and are important candidates for the treatment of COVID-19. In this review we discussed a set of compounds with favorable profile for COVID-19 treatment, including azilsartan, candesartan, eprosartan, EXP3174, olmesartan, telmisartan, and valsartan. They are effective as inverse agonists and could reduce the "cytokine storm" and reducing oxidative stress. As COVID-19 disease has several evolution patterns, the effectiveness of ARB therapy would be related to infection "timing", patient risk factors, previous use of ARBs, and the specific molecular effects of an ARB. However, controlled studies are needed to identify whether ARBs are beneficial in the treatment of patients with COVID-19.

ACE2 as a potential therapeutic target for pandemic COVID-19

SARS-CoV-2 virus invades the host through angiotensin-converting enzyme 2 (ACE2) receptors by decreasing the ACE2 expression of the host. This disturbs the dynamic equilibrium between the ACE/Ang II/AT1R axis and ACE2/Ang (1-7)/Mas receptor axis. Therefore, the clinically approved drugs belonging to (i) angiotensin converting enzyme (ACE) inhibitors such as captopril, and enalaprilat, (ii) angiotensin-receptor blockers (ARBs) such as losartan, candesartan, olmesartan, azilsartan, irbesartan, and telmisartan and (iii) the combination of ACE inhibitors and ARBs such as losartan with lisinopril and captopril with losartan, and (iv) recombinant ACE2, were studied for their ability to activate ACE2 in different medical conditions including hypertension, inflammation, cardiovascular, renal and lung diseases. These clinically approved drugs were found to activate ACE2 that had been downregulated in different medical conditions including hypertension, inflammation, cardiovascular, renal and lung diseases. Therefore, these drugs may be repurposed to re-activate the downregulated ACE2 of COVID-19 patients. These drugs either alone or in combination may be repurposed as prophylactics and therapeutics against SARS-CoV-2 virus.

Mas Receptor Activation Contributes to the Improvement of Nitric Oxide Bioavailability and Vascular Remodeling During Chronic AT1R (Angiotensin Type-1 Receptor) Blockade in Experimental Hypertension

Angiotensin (1-7) production increases during AT1R (angiotensin type-1 receptor) blockade. The contribution of Ang (1-7) (angiotensin [1-7]) and its receptor (MasR) to the favorable effect of angiotensin receptor blockers on remodeling and function of resistance arteries remains unclear. We sought to determine whether MasR contributes to the improvement of vascular structure and function during chronic AT1R blockade. Spontaneously hypertensive rats were treated with Ang (1-7) or olmesartan ± MasR antagonist A-779, or vehicle, for 14 days. Blood pressure was measured by tail cuff methodology. Mesenteric arteries were dissected and mounted on a pressurized micromyograph to evaluate media-to-lumen ratio (M/L) and endothelial function. Expression of MasR and eNOS (endothelial nitric oxide synthase) was evaluated by immunoblotting, plasma nitrate by colorimetric assay, and reactive oxygen species production by dihydroethidium staining. Independently of blood pressure, olmesartan significantly reduced M/L and improved NO bioavailability, A-779 prevented these effects. Likewise, Ang (1-7) significantly reduced M/L and NO bioavailability. MasR expression was significantly increased by Ang (1-7) as well as by olmesartan, and it was blunted in the presence of A-779. Both Ang (1-7) and olmesartan increased eNOS expression and plasma nitrite which were reduced by A-779. Superoxide generation was attenuated by olmesartan and Ang (1-7) and was blunted in the presence of A-779. These MasR-mediated actions were independent of AT2R activation since olmesartan and Ang (1-7) increased MasR expression and reduced M/L in Ang II (angiotensin II)-infused AT2R knockout mice, independently of blood pressure control. A-779 prevented these effects. Hence, MasR activation may contribute to the favorable effects of AT1R antagonism on NO bioavailability and microvascular remodeling, independently of AT2R activation and blood pressure control.

Crosstalk between coronavirus disease 2019 and cardiovascular disease and its treatment

People with cardiovascular disease (CVD) often contract coronavirus disease 2019 (COVID-19). However, the interaction between COVID-19 and CVD is unclear. In this systematic review, the available evidence for the crosstalk between COVID-19 and CVD and its treatment was analysed. A search was performed in the electronic databases MEDLINE and EMBASE. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects human cells via angiotensin-converting enzyme 2. SARS-CoV-2 can cause CVD by inducing cytokine storms, creating an imbalance in the oxygen supply and demand and disrupting the renin-angiotensin-aldosterone system; SARS-CoV-2 infection can also lead to the development of CVD through the side effects of therapeutic drugs, psychological factors, and aggravation of underlying CVD. The most common CVDs caused by SARS-CoV-2 infection are acute myocardial injury, arrhythmia, and heart failure. Studies have found that there is an interaction between COVID-19 and CVD. Underlying CVD is associated with a high risk of mortality in patients with COVID-19. SARS-CoV-2 infection can also cause new-onset CVD. Clinicians need to pay close attention to cardiovascular complications during the diagnosis and treatment of patients with COVID-19 to reduce patient mortality.

The interaction of RAAS inhibitors with COVID-19: Current progress, perspective and future

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is currently defined as the worst pandemic disease. SARS-CoV-2 infects human cells via the binding of its S protein to the receptor angiotensin-converting enzyme (ACE2). The use of ACEIs/ARBs (RAAS inhibitors) regulates the renin-angiotensin-aldosterone system (RAAS) and may increase ACE2 expression. Considering the large use of ACEIs/ARBs in hypertensive patients, some professional groups are concerned about whether the use of RAAS inhibitors affects the risk of SARS-CoV-2 infection or the risk of severe illness and mortality in COVID-19 patients. In this review, we summarize preclinical and clinical studies to investigate whether the use of ACEIs/ARBs increases ACE2 expression in animals or patients. We also analyzed whether the use of these drugs affects the risk of SARS-CoV-2 infection, severe illness or mortality based on recent studies. Finally, the review suggests that current evidence does not support the concerns.

Clinical Features of COVID-19 in Patients With Essential Hypertension and the Impacts of Renin-angiotensin-aldosterone System Inhibitors on the Prognosis of COVID-19 Patients

Hypertension is one of the most common comorbidities in patients with coronavirus disease 2019 (COVID-19). This study aimed to clarify the impact of hypertension on COVID-19 and investigate whether the prior use of renin-angiotensin-aldosterone system (RAAS) inhibitors affects the prognosis of COVID-19. A total of 996 patients with COVID-19 were enrolled, including 282 patients with hypertension and 714 patients without hypertension. Propensity score-matched analysis (1:1 matching) was used to adjust the imbalanced baseline variables between the 2 groups. Patients with hypertension were further divided into the RAAS inhibitor group (n=41) and non-RAAS inhibitor group (n=241) according to their medication history. The results showed that COVID-19 patients with hypertension had more severe secondary infections, cardiac and renal dysfunction, and depletion of CD8⁺ cells on admission. Patients with hypertension were more likely to have comorbidities and complications and were more likely to be classified as critically ill than those without hypertension. Cox regression analysis revealed that hypertension (hazard ratio, 95% CI, unmatched cohort [1.80, 1.20-2.70]; matched cohort [2.24, 1.36-3.70]) was independently associated with all-cause mortality in patients with COVID-19. In addition, hypertensive patients with a history of RAAS inhibitor treatment had lower levels of C-reactive protein and higher levels of CD4⁺ cells. The mortality of patients in the RAAS inhibitor group (9.8% versus 26.1%) was significantly lower than that of patients in the non-RAAS inhibitor group. In conclusion, hypertension may be an independent risk factor for all-cause mortality in patients with COVID-19. Patients who previously used RAAS inhibitors may have a better prognosis.

Advances in the relationship between coronavirus infection and cardiovascular diseases

The outbreak of coronavirus disease 2019 (COVID-19) has once again aroused people's concern about coronavirus. Seven human coronaviruses (HCoVs) have been discovered so far, including HCoV-229E, HCoV-NL63, HCoV-OC43, HCoV-HKU115, severe acute respiratory syndrome coronavirus, Middle East respiratory syndrome coronavirus and severe acute respiratory syndrome coronavirus 2. Existing studies show that the cardiovascular disease increased the incidence and severity of coronavirus infection. At the same time, myocardial injury caused by coronavirus infection is one of the main factors contributing to poor prognosis. In this review, the recent clinical findings about the relationship between coronaviruses and cardiovascular diseases and the underlying pathophysiological mechanisms are discussed. This review aimed to provide assistance for the prevention and treatment of COVID-19.

Azilsartan causes natriuresis due to its sympatholytic action in kidney disease

The sympathoinhibitory mechanism of azilsartan was investigated in an adenine-induced chronic renal failure model. Azilsartan exerted an antihypertensive effect, though BP elevation induced by adenine was marginal. The creatinine value was significantly lower in the azilsartan group (AZ) than in the vehicle group (VEH); furthermore, proteinuria was suppressed, and sodium excretion was augmented in the AZ group. The low frequency (LF) of systolic BP was suppressed (VEH: 4.07 ± 2.67 mmHg² vs. AZ: 3.32 ± 1.93 mmHg² P < 0.001), and the spontaneous baroreflex gain (sBRG) was augmented (VEH: 1.04 ± 0.62ms/mmHg vs. AZ: 1.38 ± 0.69 ms/mmHg, P < 0.001) in AZ. There were no significant differences in ACE1 and ACE2 expression between the groups, which indicated that the action of azilsartan on these components of the intrarenal renin-angiotensin-aldosterone system was comparatively small. Although NHE3, NKCC, and ENaC expression was similar between the groups, NaCl cotransporter (NCC) expression was markedly suppressed by azilsartan (P < 0.05). Thus, in a mild chronic kidney disease (CKD) model with slight BP elevation, the sympatholytic effect of ARB might be expected, and azilsartan might exert its natriuretic effect by NCC suppression achieved by sympathoinhibitory activity.

Angiotensin-converting enzyme 2 and renal disease

PURPOSE OF REVIEW

The renin-angiotensin system (RAS) is a pivotal player in the physiology and pathophysiology of cardiovascular and renal systems. Discovery of angiotensin-converting enzyme 2 (ACE2), capable of cleaving RAS effector peptide angiotensin (Ang) II into biologically active Ang-(1-7), has increased the complexity of our knowledge of the RAS. ACE2 expression is abundant in the kidney and is thought to provide protection against injury. This review emphasizes current experimental and clinical findings that examine ACE2 in the context of kidney injury and its potential therapeutic impact for treatment of kidney disease.

RECENT FINDINGS

Clinical studies have reported upregulation of ACE2 in urine from diabetic patients, which may be reflective of pathological shedding of renal ACE2 as suggested by mechanistic experiments. Studies in experimental models have investigated the feasibility of pharmacological induction of ACE2 for improvement of renal function, inflammation, and fibrosis.

SUMMARY

Emerging concepts about the RAS indicate that ACE2 is a critical regulator of angiotensin peptide metabolism and the pathogenesis of renal disease. Human recombinant ACE2 is available and may be a practical clinical approach to enzyme replacement. Elucidating precise roles of ACE2 throughout disease progression will enrich our view of the RAS and help identify novel targets and appropriate strategies for intervention.

Comparative effects of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers on the risk of pneumonia and severe exacerbations in patients with COPD

Objectives

This study aimed to compare the effects of angiotensin-converting-enzyme inhibitors (ACEis) and angiotensin receptor blockers (ARBs) on the risk of pneumonia and severe exacerbations in patients with COPD.

Patients and methods

All patients with COPD who used ACEis and ARBs for >90 days between 2000 and 2005 were recruited. Pairwise matching (1:1) of the ACEi and ARB groups resulted in two similar subgroups, with 6,226 patients in each. The primary outcomes were pneumonia and COPD exacerbations, and the secondary outcome was death.

Results

During the follow-up period, the incidence of pneumonia was 7.20 per 100 person-years in the ACEi group and 5.89 per 100 person-years in the ARB group. The ACEi group had a higher risk of pneumonia (adjusted hazard ratio [aHR], 1.22; 95% CI, 1.15–1.29) than the ARB group. The incidence of severe exacerbations was 0.65 per person-year for the patients receiving ACEis and 0.52 per person-year for those receiving ARBs. The patients receiving ACEis had a higher risk of severe exacerbations (aHR, 1.19; 95% CI, 1.16–1.21) than those receiving ARBs. Similar trends were noted in terms of severe exacerbations requiring hospitalization (aHR, 1.24; 95% CI, 1.21–1.28) or emergency department visits (aHR, 1.16; 95% CI, 1.13–1.18), pneumonia requiring mechanical ventilation (aHR, 1.35; 95% CI, 1.24–1.47), and mortality (aHR, 1.33; 95% CI, 1.26–1.42).

Conclusion

ARBs were associated with lower rates of pneumonia, severe pneumonia, and mortality than ACEis in patients with COPD.

Intrarenal Angiotensin-Converting Enzyme: the Old and the New

PURPOSE OF REVIEW

The intrarenal renin-angiotensin-aldosterone system (RAS) is an independent paracrine hormonal system with an increasingly prominent role in hypertension and renal disease. Two enzyme components of this system are angiotensin-converting enzyme (ACE) and more recently discovered ACE2. The purpose of this review is to describe recent discoveries regarding the roles of intrarenal ACE and ACE2 and their interaction.

RECENT FINDINGS

Renal tubular ACE contributes to salt-sensitive hypertension. Additionally, the relative expression and activity of intrarenal ACE and ACE2 are central to promoting or inhibiting different renal pathologies including renovascular hypertension, diabetic nephropathy, and renal fibrosis. Renal ACE and ACE2 represent two opposing axes within the intrarenal RAS system whose interaction determines the progression of several common disease processes. While this relationship remains complex and incompletely understood, further investigations hold the potential for creating novel approaches to treating hypertension and kidney disease.

Angiotensin II type 1a receptor-deficient mice develop angiotensin II-induced oxidative stress and DNA damage without blood pressure increase

Hypertensive patients have an increased risk of developing kidney cancer. We have shown in vivo that besides elevating blood pressure, angiotensin II causes DNA damage dose dependently. Here, the role of blood pressure in the formation of DNA damage is studied. Mice lacking one of the two murine angiotensin II type 1 receptor (AT1R) subtypes, AT1aR, were equipped with osmotic minipumps, delivering angiotensin II during 28 days. Parameters of oxidative stress and DNA damage of kidneys and hearts of AT1aR-knockout mice were compared with wild-type (C57BL/6) mice receiving angiotensin II, and additionally, with wild-type mice treated with candesartan, an antagonist of both AT1R subtypes. In wild-type mice, angiotensin II induced hypertension, reduced kidney function, and led to a significant formation of reactive oxygen species (ROS). Furthermore, genomic damage was markedly increased in this group. All these responses to angiotensin II could be attenuated by concurrent administration of candesartan. In AT1aR-deficient mice treated with angiotensin II, systolic pressure was not increased, and renal function was not affected. However, angiotensin II still led to an increase of ROS in kidneys and hearts of these animals. Additionally, genomic damage in the form of double-strand breaks was significantly induced in kidneys of AT1aR-deficient mice. Our results show that angiotensin II induced ROS production and DNA damage even without the presence of AT1aR and independently of blood pressure changes.

Candesartan Restores the Amyloid Beta-Inhibited Proliferation of Neural Stem Cells by Activating the Phosphatidylinositol 3-Kinase Pathway

Background and Purpose

Neurogenesis in the adult brain is important for memory and learning, and the alterations in neural stem cells (NSCs) may be an important aspect of Alzheimer's disease (AD) pathogenesis. The phosphatidylinositol 3-kinase (PI3K) pathway has been suggested to have an important role in neuronal cell survival and is highly involved in adult neurogenesis. Candesartan is an angiotensin II receptor antagonist used for the treatment of hypertension and several studies have reported that it also has some neuroprotective effects. We investigated whether candesartan could restore the amyloid-β(25–35) (Aβ_25-35) oligomer-inhibited proliferation of NSCs by focusing on the PI3K pathway.

Methods

To evaluate the effects of candesartan on the Aβ_25-35 oligomer-inhibited proliferation of NSCs, the NSCs were treated with several concentrations of candesartan and/or Aβ_25-35 oligomers, and MTT assay and trypan blue staining were performed. To evaluate the effect of candesartan on the Aβ-inhibited proliferation of NSCs, we performed a bromodeoxyuridine (BrdU) labeling assay. The levels of p85α PI3K, phosphorylated Akt (pAkt) (Ser473), phosphorylated glycogen sinthase kinase-3β (pGSK-3β) (Ser9), and heat shock transcription factor-1 (HSTF-1) were analyzed by Western blotting.

Results

The BrdU assays demonstrated that NSC proliferation decreased with Aβ_25-35 oligomer treatment; however, a combined treatment with candesartan restored it. Western blotting displayed that candesartan treatment increased the expression levels of p85α PI3K, pAkt (Ser473), pGSK-3β (Ser9), and HSTF. The NSCs were pretreated with a PI3K inhibitor, LY294002; the effects of candesartan on the proliferation of NSCs inhibited by Aβ_25-35 oligomers were almost completely blocked.

Conclusions

Together, these results suggest that candesartan restores the Aβ_25-35 oligomer-inhibited proliferation of NSCs by activating the PI3K pathway.

Ameliorative Effect of Coenzyme Q10 and/or Candesartan on Carboplatin-Induced Nephrotoxicity: Roles of Apoptosis, Transforming Growth Factor-Β1, Nuclear Factor Kappa-B And The Nrf2/HO-1 Pathway

Background:

Carboplatin is a drug that is used for treatment of many types of cancer. However, it may produce serious nephrotoxicity. Candesartan is angiotensin II receptor antagonist employed mainly for control of hypertension. Coenzyme Q10 (CoQ10) is a fat-soluble substance which was proven to have potent antioxidant and anti-inflammatory properties.

Aim:

Our aim was to study the effects of candesartan and/or CoQ10 on carboplatin-induced nephrotoxicity in mice.

Methods:

Sixty mice were divided into 6 equal groups: Control untreated; carboplatin; carboplatin + candesartan; carboplatin + CoQ10; carboplatin + carboxymethyl cellulose; and carboplatin + candesartan + CoQ10 group. Kidney weight/body weight ratio, blood urea, serum creatinine, creatinine clearance, urinary N-acetyl beta-D-glucosaminidase (NAG), gamma glutamyl transpeptidase (GGT) and the urinary albumin excretion rate (UAER) were determined. Renal tissue catalase (CAT), glutathione reductase (GR), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), heme oxygenase-1 (HO-1), transforming growth factor beta-1 (TGF-β1), tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) were also determined, along with mitochondrial complex I activity. In addition, portions of the kidney were subjected to histopathological and immunohistochemical examination.

Results:

Candesartan and/or CoQ10 induced significant improvement of renal and mitochondrial functions with significant increase in tissue CAT, GR, Nrf2 and HO-1 content associated with significant decrease in the kidney weight/body weight ratio, tissue TGF-β1, TNF-α and IL-6 and alleviation of the histopathological and immunohistochemical changes as compared to carboplatin alone group. These effects were more significant in candesartan/CoQ10 combination group compared to either candesartan or CoQ10 alone.

Conclusion:

Candesartan/CoQ10 combination might represent a beneficial therapeutic modality for amelioration of carboplatin-induced nephrotoxicity.

Significance of angiotensin 1-7 coupling with MAS1 receptor and other GPCRs to the renin-angiotensin system: IUPHAR Review 22

Angiotensins are a group of hormonal peptides and include angiotensin II and angiotensin 1-7 produced by the renin angiotensin system. The biology, pharmacology and biochemistry of the receptors for angiotensins were extensively reviewed recently. In the review, the receptor nomenclature committee was not emphatic on designating MAS1 as the angiotensin 1-7 receptor on the basis of lack of classical G protein signalling and desensitization in response to angiotensin 1-7, as well as a lack of consensus on confirmatory ligand pharmacological analyses. A review of recent publications (2013-2016) on the rapidly progressing research on angiotensin 1-7 revealed that MAS1 and two additional receptors can function as 'angiotensin 1-7 receptors', and this deserves further consideration. In this review we have summarized the information on angiotensin 1-7 receptors and their crosstalk with classical angiotensin II receptors in the context of the functions of the renin angiotensin system. It was concluded that the receptors for angiotensin II and angiotensin 1-7 make up a sophisticated cross-regulated signalling network that modulates the endogenous protective and pathogenic facets of the renin angiotensin system.