Targeting the Renin-Angiotensin System (RAS) for Neuropsychiatric Disorders

BACKGROUND

Neuropsychiatric disorders, such as mood disorders, schizophrenia, and Alzheimer's disease (AD) and related dementias, are associated to significant morbidity and mortality worldwide. The pathophysiological mechanisms of neuropsychiatric disorders remain to be fully elucidated, which has hampered the development of effective therapies. The Renin Angiotensin System (RAS) is classically viewed as a key regulator of cardiovascular and renal homeostasis. The discovery that RAS components are expressed in the brain pointed out a potential role for this system in central nervous system (CNS) pathologies. The understanding of RAS involvement in the pathogenesis of neuropsychiatric disorders may contribute to identifying novel therapeutic targets.

AIMS

We aim to report current experimental and clinical evidence on the role of RAS in physiology and pathophysiology of mood disorders, schizophrenia, AD and related dementias. We also aim to discuss bottlenecks and future perspectives that can foster the development of new related therapeutic strategies.

CONCLUSION

The available evidence supports positive therapeutic effects for neuropsychiatric disorders with the inhibition/antagonism of the ACE/Ang II/AT1 receptor axis or the activation of the ACE2/Ang-(1-7)/Mas receptor axis. Most of this evidence comes from pre-clinical studies and clinical studies lag much behind, hampering a potential translation into clinical practice.

Angiotensin converting enzyme (ACE) inhibitors as radiation countermeasures for long-duration space flights

Angiotensin converting enzyme (ACE) inhibitors are effective countermeasures to chronic radiation injuries in rodent models, and there is evidence for similar effects in humans. In rodent models ACE inhibitors are effective mitigators of radiation injury to kidney, lung, central nervous system (CNS) and skin, even when started weeks after irradiation. In humans, the best data for their efficacy as radiation countermeasures comes from retrospective studies of injuries in radiotherapy patients. We propose that ACE inhibitors, at doses approved for human use for other indications, could be used to reduce the risk of chronic radiation injuries from deep-space exploration. Because of the potential interaction of ACE inhibitors and microgravity (due to effects of ACE inhibitors on fluid balance) use might be restricted to post-exposure when/if radiation exposures reached a danger level. A major unresolved issue for this approach is the sparse evidence for the efficacy of ACE inhibitors after low-dose-rate exposure and/or for high-LET radiations (as would occur on long-duration space flights). A second issue is that the lack of a clear mechanism of action of the ACE inhibitors as mitigators makes obtaining an appropriate label under the Food and Drug Administration Animal Rule difficult.

Quercetin Reduces the Virulence of S. aureus by Targeting ClpP to Protect Mice from MRSA-Induced Lethal Pneumonia

The dramatic increase of methicillin-resistant Staphylococcus aureus (MRSA) poses a great challenge to the treatment of Staphylococcus aureus (S. aureus) infections. Therefore, there is an urgent need to identify novel anti-infective agents to attack new targets to overcome antibiotic resistance. Casein hydrolase P (ClpP) is a key virulence factor in S. aureus to maintain cellular homeostasis. We screened from flavonoids and finally determined that quercetin could effectively attenuate the virulence of MRSA. The results of the thermal shift assay showed that quercetin could bind to ClpP and reduce the thermal stability of ClpP, and the KD value between quercetin and ClpP was 197 nM as determined by localized surface plasmon resonance. We found that quercetin exhibited a protective role of a mouse model of MRSA-induced lethal infection in a murine model. Based on the above facts, quercetin, as a ClpP inhibitor, could be further developed as a potential candidate for antivirulence agents to combat S. aureus infections. IMPORTANCE The resistance of Staphylococcus aureus (S. aureus) to various antibiotics has increased dramatically, and thus the development of new anti-infective drugs with new targets is urgently needed to combat resistance. Caseinolytic peptidase P (ClpP) is a casein hydrolase that has been shown to regulate a variety of important virulence factors in S. aureus. Here, we found that quercetin, a small-molecule compound from traditional Chinese herbal flavonoids, effectively inhibits ClpP activity. Quercetin attenuates the expression of multiple virulence factors in S. aureus and effectively protects mice from lethal pneumonia caused by MRSA. In conclusion, we determined that quercetin is a ClpP inhibitor and an effective lead compound for the development of a virulence factor-based treatment for S. aureus infection.

Evidence for treatment with estradiol for women with SARS-CoV-2 infection

BACKGROUND

Given that an individual's age and gender are strongly predictive of coronavirus disease 2019 (COVID-19) outcomes, do such factors imply anything about preferable therapeutic options?

METHODS

An analysis of electronic health records for a large (68,466-case), international COVID-19 cohort, in 5-year age strata, revealed age-dependent sex differences. In particular, we surveyed the effects of systemic hormone administration in women. The primary outcome for estradiol therapy was death. Odds ratios (ORs) and Kaplan-Meier survival curves were analyzed for 37,086 COVID-19 women in two age groups: pre- (15-49 years) and peri-/post-menopausal (> 50 years).

RESULTS

The incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is higher in women than men (by about + 15%) and, in contrast, the fatality rate is higher in men (about + 50%). Interestingly, the relationships between these quantities are linked to age: pre-adolescent girls and boys had the same risk of infection and fatality rate, while adult premenopausal women had a significantly higher risk of infection than men in the same 5-year age stratum (about 16,000 vs. 12,000 cases). This ratio changed again in peri- and postmenopausal women, with infection susceptibility converging with men. While fatality rates increased continuously with age for both sexes, at 50 years, there was a steeper increase for men. Thus far, these types of intricacies have been largely neglected. Because the hormone 17ß-estradiol influences expression of the human angiotensin-converting enzyme 2 (ACE2) protein, which plays a role in SARS-CoV-2 cellular entry, propensity score matching was performed for the women's sub-cohort, comparing users vs. non-users of estradiol. This retrospective study of hormone therapy in female COVID-19 patients shows that the fatality risk for women > 50 years receiving estradiol therapy (user group) is reduced by more than 50%; the OR was 0.33, 95% CI [0.18, 0.62] and the hazard ratio (HR) was 0.29, 95% CI [0.11,0.76]. For younger, pre-menopausal women (15-49 years), the risk of COVID-19 fatality is the same irrespective of estradiol treatment, probably because of higher endogenous estradiol levels.

CONCLUSIONS

As of this writing, still no effective drug treatment is available for COVID-19; since estradiol shows such a strong improvement regarding fatality in COVID-19, we suggest prospective studies on the potentially more broadly protective roles of this naturally occurring hormone.

Design of an engineered ACE2 as a novel therapeutics against COVID-19

The interaction between the angiotensin-converting enzyme 2 (ACE2) and the receptor binding domain (RBD) of the spike protein from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) plays a pivotal role in virus entry into the host cells. Since recombinant ACE2 protein has been suggested as an anti-SARS-CoV-2 therapeutic agent, this study was conducted to design an ACE2 protein with more desirable properties. In this regard, the amino acids with central roles in enzymatic activity of the ACE2 were substituted. Moreover, saturation mutagenesis at the interaction interface between the ACE2 and RBD was performed to increase their interaction affinity. The best mutations to increase the structural and thermal stability of the ACE2 were also selected based on B factors and mutation effects. The obtained resulted revealed that the Arg273Gln and Thr445Gly mutation have drastically reduced the binding affinity of the angiotensin-II into the active site of ACE2. The Thr27Arg mutation was determined to be the most potent mutation to increase the binding affinity. The Asp427Arg mutation was done to decrease the flexibility of the region with high B factor. The Pro451Met mutation along with the Gly448Trp mutation was predicted to increase the thermodynamic stability and thermostability of the ACE2. The designed therapeutic ACE2 would have no enzymatic activity while it could bear stronger interaction with Spike glycoprotein of the SARS-CoV-2. Moreover, decreased in vivo enzymatic degradation would be anticipated due to increased thermostability. This engineered ACE2 could be exploited as a novel therapeutic agent against COVID-19 after necessary evaluations.

Neither ACEIs nor ARBs are associated with respiratory distress or mortality in COVID-19 results of a prospective study on a hospital-based cohort

Considerable concern has emerged for the potential harm in the use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor inhibitors (ARBs) in COVID-19 patients, given that ACEIs and ARBs may increase the expression of ACE2 receptors that represent the way for coronavirus 2 to entry into the cell and cause severe acute respiratory syndrome. Assess the effect of ACEI/ARBs on outcome in COVID-19 patients. Hospital-based prospective study. A total of 431 patients consecutively presenting at the Emergency Department and found to be affected by COVID-19 were assessed. Relevant clinical and laboratory variables were recorded, focusing on the type of current anti hypertensive treatment. Outcome variables were NO, MILD, SEVERE respiratory distress (RD) operationally defined and DEATH. Hypertension was the single most frequent comorbidity (221/431 = 51%). Distribution of antihypertensive treatment was: ACEIs 77/221 (35%), ARBs 63/221 (28%), OTHER than ACEIs or ARBs 64/221 (29%). In 17/221 (8%) antihypertensive medication was unknown. The proportion of patients taking ACEIs, ARBs or OTHERs who developed MILD or SEVERE RD was 43/77 (56%), 33/53 (52%), 39/64 (61%) and 19/77 (25%), 16/63 (25%) and 16/64 (25%), respectively, with no statistical difference between groups. Despite producing a RR for SEVERE RD of 2.59 (95% CI 1.93-3.49), hypertension was no longer significant in a logistic regression analysis that identified age, CRP and creatinine as the sole independent predictors of SEVERE RD and DEATH. ACEIs and ARBs do not promote a more severe outcome of COVID-19. There is no reason why they should be withheld in affected patients.

No small matter: a perspective on nanotechnology-enabled solutions to fight COVID-19

There is an urgent need for safe and effective approaches to combat COVID-19. Here, we asked whether lessons learned from nanotoxicology and nanomedicine could shed light on the current pandemic. SARS-CoV-2, the causative agent, may trigger a mild, self-limiting disease with respiratory symptoms, but patients may also succumb to a life-threatening systemic disease. The host response to the virus is equally complex and studies are now beginning to unravel the immunological correlates of COVID-19. Nanotechnology can be applied for the delivery of antiviral drugs or other repurposed drugs. Moreover, recent work has shown that synthetic nanoparticles wrapped with host-derived cellular membranes may prevent virus infection. We posit that nanoparticles decorated with ACE2, the receptor for SARS-CoV-2, could be exploited as decoys to intercept the virus before it infects cells in the respiratory tract. However, close attention should be paid to biocompatibility before such nano-decoys are deployed in the clinic.

The mechanistic overview of SARS-CoV-2 using angiotensin-converting enzyme 2 to enter the cell for replication: possible treatment options related to the renin-angiotensin system

The SARS-CoV-2 pandemic is a healthcare crisis caused by insufficient knowledge applicable to effectively combat the virus. Therefore, different scientific discovery strategies need to be connected, to generate a rational treatment which can be made available as rapidly as possible. This relies on a solid theoretical understanding of the mechanisms of SARS-CoV-2 infection and host responses, which is coupled to the practical experience of clinicians that are treating patients. Because SARS-CoV-2 enters the cell by binding to angiotensin-converting enzyme 2 (ACE2), targeting ACE2 to prevent such binding seems an obvious strategy to combat infection. However, ACE2 performs its functions outside the cell and was found to enter the cell only by angiotensin II type 1 receptor (AT1R)-induced endocytosis, after which ACE2 is destroyed. This means that preventing uptake of ACE2 into the cell by blocking AT1R would be a more logical approach to limit entry of SARS-CoV-2 into the cell. Since ACE2 plays an important protective role in maintaining key biological processes, treatments should not disrupt the functional capacity of ACE2, to counterbalance the negative effects of the infection. Based on known mechanisms and knowledge of the characteristics of SARS-CoV we propose the hypothesis that the immune system facilitates SARS-CoV-2 replication which disrupts immune regulatory mechanisms. The proposed mechanism by which SARS-CoV-2 causes disease immediately suggests a possible treatment, since the AT1R is a key player in this whole process. AT1R antagonists appear to be the ideal candidate for the treatment of SARS-CoV-2 infection. AT1R antagonists counterbalance the negative consequences of angiotesnin II and, in addition, they might even be involved in preventing the cellular uptake of the virus without interfering with ACE2 function. AT1R antagonists are widely available, cheap, and safe. Therefore, we propose to consider using AT1R antagonists in the treatment of SARS-CoV-2.

Comprehensive analysis of drugs to treat SARS‑CoV‑2 infection: Mechanistic insights into current COVID‑19 therapies (Review)

The major impact produced by the severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) focused many researchers attention to find treatments that can suppress transmission or ameliorate the disease. Despite the very fast and large flow of scientific data on possible treatment solutions, none have yet demonstrated unequivocal clinical utility against coronavirus disease 2019 (COVID‑19). This work represents an exhaustive and critical review of all available data on potential treatments for COVID‑19, highlighting their mechanistic characteristics and the strategy development rationale. Drug repurposing, also known as drug repositioning, and target based methods are the most used strategies to advance therapeutic solutions into clinical practice. Current in silico, in vitro and in vivo evidence regarding proposed treatments are summarized providing strong support for future research efforts.

The renin-angiotensin-aldosterone system: Role in pathogenesis and potential therapeutic target in COVID-19

Coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 novel coronavirus, has spread worldwide causing high fatality rates. Neither a vaccine nor specific therapeutic approaches are available, hindering the fight against this disease and making better understanding of its pathogenesis essential. Despite similarities between SARS-CoV-2 and SARS-CoV, the former has unique characteristics which represent a great challenge to physicians. The mechanism of COVID-19 infection and pathogenesis is still poorly understood. In the present review, we highlight possible pathways involved in the pathogenesis of COVID-19 and potential therapeutic targets, focusing on the role of the renin-angiotensin-aldosterone system.

Angiotensin converting enzyme-2 as therapeutic target in COVID-19

The pandemic of coronavirus disease 2019 (COVID-19) is a global health emergency that poses a significant threat to world people's health. This outbreak causes major challenges to healthcare systems. Given the lack of effective treatments or vaccine for it, the identification of novel and safe drugs against COVID-19 infection is an urgent need. Angiotensin-converting enzyme 2 (ACE2) is not only an entry receptor of the SARS-CoV-2 virus, the virus that causes COVID-19, but also can protect from lung injury. In this view, we highlighted potential approaches to address ACE2-mediated SARS-CoV-2 virus, including 1) delivering an excessive soluble form of ACE2 (recombinant human ACE2: rhACE2) and 2) inhibition of the interaction between SARS-CoV-2 virus and ACE2 by some compounds with competitive effects (morphine and codeine). Further clinical trials in this regard can reveal a more definite conclusion against the COVID-19 disaster.

Inhaled modified angiotensin converting enzyme 2 (ACE2) as a decoy to mitigate SARS-CoV-2 infection

COVID-19 is a new zoonotic disease caused by the SARS-CoV-2 virus. Since its emergence in Wuhan City, China, the virus has rapidly spread across the globe causing calamitous health, economic and societal consequences. It causes disproportionately severe disease in the elderly and those with co-morbidities, such as hypertension and diabetes. There is currently no proven treatment for COVID-19 and a safe and effective vaccine is at least a year away. The virus gains access to the respiratory epithelium through cell surface angiotensin converting enzyme 2 (ACE2). The receptor binding domain (RBD) of the virus is unlikely to mutate without loss of pathogenicity and thus represents an attractive target for antiviral treatment. Inhaled modified recombinant human ACE2, may bind SARS-CoV-2 and mitigate lung damage. This decoy strategy is unlikely to provoke an adverse immune response and may reduce morbidity and mortality in high-risk groups.

Epidemiologic and clinical characteristics of heart transplant recipients during the 2019 coronavirus outbreak in Wuhan, China: A descriptive survey report

BACKGROUND

The epidemiologic and clinical characteristics of heart transplant (HTx) recipients during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic remains unclear. We studied the characteristics of HTx recipients from December 20, 2019, to February 25, 2020, in an effort to understand their risk and outcomes.

METHODS

All accessible HTx recipients were included in this single-center retrospective study. We collected information on the recipients using a web-based questionnaire as well as the hospital database.

RESULTS

We followed 87 HTx recipients (72.4% were men, and the average age was 51 years). A total of 79 recipients resided in Hubei, and 57 recipients had a Wuhan-related history of travel or contact. Most took precautionary measures while in contact with suspicious crowds, and 96.6% of the families and communities undertook prevention and quarantine procedures. Four upper airway infections were reported, and 3 of them tested negative for SARS-CoV-2 (the fourth recovered and was not tested). All cases were mild and successfully recovered after proper treatment. Laboratory results of 47 HTx cases within the last 2 months were extracted. Of these, 21.3% of recipients had pre-existing lymphopenia, and 87.2% of recipients had a therapeutic concentration of tacrolimus (5-12 ng/ml). Liver and kidney insufficiency was seen in 5 and 6 recipients, respectively.

CONCLUSION

HTx recipients who practiced appropriate prevention measures had a low rate of infection with SARS-CoV-2 and transition to the associated disease COVID-19. These early data will require confirmation as the pandemic establishes around the world.

The ACE I/D polymorphism does not explain heterogeneity of natural course and response to enzyme replacement therapy in Pompe disease

The majority of children and adults with Pompe disease in the population of European descent carry the leaky splicing GAA variant c.-32-13T>G (IVS1) in combination with a fully deleterious GAA variant on the second allele. The phenotypic spectrum of this patient group is exceptionally broad, with symptom onset ranging from early infancy to late adulthood. In addition, the response to enzyme replacement therapy (ERT) varies between patients. The insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme (ACE) has been suggested to be a modifier of disease onset and/or response to ERT. Here, we have investigated the effect of the ACE I/D polymorphism in a relatively large cohort of 131 children and adults with Pompe disease, of whom 112 were followed during treatment with ERT for 5 years. We assessed the use of wheelchair and mechanical ventilation, muscle strength assessed via manual muscle testing and hand-held dynamometry (HHD), distance walked on the six-minute walk test (6MWT), forced vital capacity (FVC) in sitting and supine position and daily-life activities assessed by R-PAct. Cross sectional analysis at first visit showed no differences between the genotypes with respect to age at first symptoms, diagnosis, wheelchair use, or ventilator use. Also response to ERT over 5 years assessed by linear mixed model analyses showed no significant differences between ACE groups for any of the outcome measures. The patient cohort contained 24 families with 54 siblings. Differences in ACE genotype could neither explain inter nor intra familial differences. We conclude that the ACE I/D polymorphism does not explain the large variation in disease severity and response to ERT observed among Pompe patients with the same c.-32-13T>G GAA variant.

Novel ACE2-Fc chimeric fusion provides long-lasting hypertension control and organ protection in mouse models of systemic renin angiotensin system activation

Angiotensin-converting enzyme 2 (ACE2) is a carboxypeptidase that potently degrades angiotensin II to angiotensin 1-7. Previous studies showed that injection of the enzymatic ectodomain of recombinant ACE2 (rACE2) markedly increases circulatory levels of ACE2 activity, and effectively lowered blood pressure in angiotensin II-induced hypertension. However, due to the short plasma half-life of rACE2, its therapeutic potential for chronic use is limited. To circumvent this, we generated a chimeric fusion of rACE2 and the immunoglobulin fragment Fc segment to increase its plasma stability. This rACE2-Fc fusion protein retained full peptidase activity and exhibited greatly extended plasma half-life in mice, from less than two hours of the original rACE2, to over a week. A single 2.5 mg/kg injection of rACE2-Fc increased the overall angiotensin II-conversion activities in blood by up to 100-fold and enhanced blood pressure recovery from acute angiotensin II induced hypertension seven days after administration. To assess rACE2-Fc given weekly on cardiac protection, we performed studies in mice continuously infused with angiotensin II for 28 days and in a Renin transgenic mouse model of hypertension. The angiotensin II infused mice achieved sustained blood pressure control and reduced cardiac hypertrophy and fibrosis. In chronic hypertensive transgenic mice, weekly injections of rACE2-Fc effectively lowered plasma angiotensin II and blood pressure. Additionally, rACE2-Fc ameliorated albuminuria, and reduced kidney and cardiac fibrosis. Thus, our chimeric fusion strategy for rACE2-Fc is suitable for future development of new renin angiotensin system-based inhibition therapies.

Drug and Drug-Device Therapy in Heart Failure Patients in the Post-COMET and SCD-HeFT Era

Reduced left ventricular ejection fraction and heart failure are the most important risk factors for sudden cardiac death. Recent trials have contributed to the knowledge base of critical therapies for the treatment of left ventricular systolic dysfunction and heart failure as it relates to arrhythmic and sudden cardiac death. Both pharmacologic and device therapies can reduce sudden cardiac death. The trials discussed in this paper have identified the pharmacologic and device interventions that are likely to improve the length and quality of life of the patient with left ventricular dysfunction and reduce the risk of sudden cardiac death. The mortality and anti-arrhythmic effects of angiotensin-converting enzyme inhibitors and β-blockers have been confirmed in large-scale controlled clinical heart failure trials. Recent trials have evaluated which agents are most effective and which patients will derive the most benefit from device therapy in terms of the reduction in the risk of sudden cardiac death and in the amelioration of heart failure. The recent data from the Carvedilol or Metoprolol European Trial (COMET) and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) are discussed as the latest in the series of landmark studies that have shaped the current approaches to treating patients with heart failure and that have altered the heart failure treatment paradigm.

Angiotensin-Converting Enzyme 2 Attenuates Bleomycin-Induced Lung Fibrosis in Mice

BACKGROUND

Local renin-angiotensin system (RAS) activation has been shown to play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). It has been reported that angiotensin-converting enzyme 2 (ACE2) could inhibit RAS-mediated epithelial injury and fibrogenesis and that ACE2 deficiency could aggravate acute and chronic lung injury. Through research, it could be deduced that ACE2 could protect against pulmonary fibrosis as a therapeutic target.

METHODS

Time-course analysis of the pathological characteristics of bleomycin-induced lung fibrosis was undertaken in a mouse model, and the effect of exogenous ACE2 on lung fibrosis was studied. Immunohistchemistry (IHC) staining and western blot (WB) testing for AGT and ACE2 were performed to evaluate the regulation of local RAS. TUNEL staining was used to observe epithelial apoptosis. Leukocyte common antigen (LCA) and pulmonary surfactant-associated protein A (SP-A) IHC staining and WB testing were performed to assess the inflammatory response and epithelial regeneration. Masson's staining and a hydroxyproline assay were performed to examine collagen deposition. IHC staining and WB testing for TGF-β1 and α-SMA were performed to investigate the regulation of pro-fibrotic cytokines and the activation of fibroblasts.

RESULTS

Exogenous ACE2 attenuated bleomycin-induced lung fibrosis by reversing the reduction of local ACE2 and by suppressing the elevation of AGT. ACE2 decreased the apoptosis index and LCA levels and ameliorated the dynamic change in SP-A level, thus protecting against epithelial injury. Reductions of TGF-β1 and α-SMA were also found in ACE2-treated mice, indicating the inhibition of fibrogenesis.

CONCLUSION

ACE2 attenuated bleomycin-induced lung fibrosis as an anti-inflammatory anti-apoptotic and anti-fibrotic agent, and it might be a promising therapeutic target for IPF.

Update on angioedema: evaluation, diagnosis, and treatment

Hereditary Angioedema (HAE) is a multisystem, autosomal dominant disease that affects ∼1:10,000 to 1:50,000 individuals in the United States. The disease has several clinical characteristics that distinguish it from other forms of angioedema. Recurrent swelling attacks involve the abdomen, face, extremities, genitalia, oropharynx, or larynx without urticaria. The swelling attacks are typically unilateral, nonpitting, nonpruritic, and, although uncomfortable, are often painless. Other forms of isolated angioedema such as acquired angioedema and angiotensin-converting enzyme-induced angioedema have similar characteristics of HAE. Therefore, evaluation of patients with recurrent angioedema should be directed at excluding these different forms of angioedema before a diagnosis of idiopathic angioedema is made. The objective of this article is to provide an overview of the differential diagnosis of angioedema that reflects the angioedema guidelines that are currently in development.

Angiotensin-converting enzyme inhibitors and cardiovascular outcomes in patients on maintenance hemodialysis

BACKGROUND

Persons with end-stage renal disease (ESRD) on hemodialysis carry an exceptionally high burden of cardiovascular disease. Angiotensin-converting enzyme inhibitors (ACEIs) are recommended for patients on dialysis, but there are few data regarding their effectiveness in ESRD.

METHODS

We conducted a secondary analysis of results of the HEMO study, a randomized trial of dialysis dose and membrane flux in patients on maintenance hemodialysis. We focused on the nonrandomized exposure of ACEI use, using proportional hazards regression and a propensity score analysis. The primary outcome was all-cause mortality. Secondary outcomes examined in the present analysis were cardiovascular hospitalization, heart failure hospitalization, and the composite outcomes of death or cardiovascular hospitalization and death or heart failure hospitalization.

RESULTS

In multivariable-adjusted analyses, there were no significant associations among ACEI use and mortality (hazard ratio 0.97, 95% CI 0.82-1.14), cardiovascular hospitalization, and either composite outcome. Angiotensin-converting enzyme inhibitor use was associated with a higher risk of heart failure hospitalization (hazard ratio 1.41, 95% CI 1.11-1.80). In the propensity score-matched cohort, ACEI use was not significantly associated with any outcomes, including heart failure hospitalization.

CONCLUSIONS

In a well-characterized cohort of patients on maintenance hemodialysis, ACEI use was not significantly associated with mortality or cardiovascular morbidity. The higher risk of heart failure hospitalization associated with ACEI use may not only reflect residual confounding but also highlights gaps in evidence when applying treatments proven effective in the general population to patients with ESRD. Our results underscore the need for definitive trials in ESRD to inform the treatment of cardiovascular disease.

Human recombinant ACE2 reduces the progression of diabetic nephropathy

OBJECTIVE

Diabetic nephropathy is one of the most common causes of end-stage renal failure. Inhibition of ACE2 function accelerates diabetic kidney injury, whereas renal ACE2 is downregulated in diabetic nephropathy. We examined the ability of human recombinant ACE2 (hrACE2) to slow the progression of diabetic kidney injury.

RESEARCH DESIGN AND METHODS

Male 12-week-old diabetic Akita mice (Ins2(WT/C96Y)) and control C57BL/6J mice (Ins2(WT/WT)) were injected daily with placebo or with rhACE2 (2 mg/kg, i.p.) for 4 weeks. Albumin excretion, gene expression, histomorphometry, NADPH oxidase activity, and peptide levels were examined. The effect of hrACE2 on high glucose and angiotensin II (ANG II)-induced changes was also examined in cultured mesangial cells.

RESULTS

Treatment with hrACE2 increased plasma ACE2 activity, normalized blood pressure, and reduced the urinary albumin excretion in Akita Ins2(WT/C96Y) mice in association with a decreased glomerular mesangial matrix expansion and normalization of increased alpha-smooth muscle actin and collagen III expression. Human recombinant ACE2 increased ANG 1-7 levels, lowered ANG II levels, and reduced NADPH oxidase activity. mRNA levels for p47(phox) and NOX2 and protein levels for protein kinase Calpha (PKCalpha) and PKCbeta1 were also normalized by treatment with hrACE2. In vitro, hrACE2 attenuated both high glucose and ANG II-induced oxidative stress and NADPH oxidase activity.

CONCLUSIONS

Treatment with hrACE2 attenuates diabetic kidney injury in the Akita mouse in association with a reduction in blood pressure and a decrease in NADPH oxidase activity. In vitro studies show that the protective effect of hrACE2 is due to reduction in ANG II and an increase in ANG 1-7 signaling.

[Lessons from SARS: a new potential therapy for acute respiratory distress syndrome (ARDS) with angiotensin converting enzyme 2 (ACE2)]

During several months of 2002, severe acute respiratory syndrome (SARS) caused by SARS-coronavirus (SARS-CoV) spread rapidly from China throughout the world causing more than 800 deaths due to the development of acute respiratory distress syndrome (ARDS). Interestingly, a novel homologue of angiotensin converting-enzyme (ACE), termed angiotensin converting enzyme 2 (ACE2) has been identified as a receptor for SARS-CoV. ACE and ACE2 share homology in their catalytic domain and provide different key functions in the renin-angiotensin system. ACE cleaves angiotensin I to generate angiotensin II that is a key effector peptide of the system and exerts multiple biological functions, whereas ACE2 reduces angiotensin II levels and thus is a negative regulator of the system. Importantly, our recent studies using ACE2 knockout mice have demonstrated that ACE2 protects murine lungs from ARDS. Furthermore, SARS-CoV infections and the Spike protein of the SARS-CoV reduce ACE2 expression. Notably, injection of SARS-CoV Spike into mice worsens acute lung failure in vivo that can be attenuated by blocking the renin-angiotensin pathway, suggesting the activation of pulmonary RAS influences the pathogenesis of ARDS and SARS.

New antiarrhythmic treatment of atrial fibrillation

Antiarrhythmic pharmaceutical development for the treatment of atrial fibrillation (AF) is moving in several directions. The efficacy of existing drugs, such as carvedilol, for rate control and, possibly, suppression of AF, is more appreciated. Efforts are being made to modify existing agents, such as amiodarone, in an attempt to ameliorate safety and adverse effect concerns. This has resulted in promising data from the deiodinated amiodarone analog, dronedarone, and further work with celivarone and ATI-2042. In an attempt to minimize ventricular proarrhythmia, atrial selective drugs, such as intravenous vernakalant, have demonstrated efficacy in terminating AF in addition to promising data in suppression recurrences when used orally. Several other atrial selective drugs are being developed by multiple manufacturers. Other novel therapeutic mechanisms, such as drugs that enhance GAP junction conduction, are being developed to achieve more effective drug therapy than is offered by existing compounds. Finally, nonantiarrhythmic drugs, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, high-mobility group coenzyme A enzyme inhibitors and omega-3 fatty acids/fish oil, appear to have a role in suppressing AF in certain patient subtypes. Future studies will clarify the role of these drugs in treating AF.

The Influence of Angiotensin-Converting Enzyme Gene of Donor and Recipient on the Function of Transplanted Kidney

One of the genes that is supposed to influence renal graft function is the one encoding angiotensin I-converting enzyme (ACE). It shows polymorphism in the presence (I allele) or absence (D allele) of a 287-base pair fragment. The question arises whether ACE gene polymorphism of the recipient and donor influences renal graft survival. This prospective study included 94 recipients who underwent ACE genotyping (DD, DI, II) and measured their creatinine clearance after cimetidine administration. These factors were correlated with the occurrence of acute or chronic rejection and of pharmacologic treatment of hypertension. In 27 recipients it was possible to obtain the ACE genotype of the donor. Among the recipients, 36 proved to be DD genotype, 38 ID, and 20 II. Among the donors, 10 proved to be DD genotype, 10 ID, and 7 II. The changes in creatinine clearance after cimetidine administration were not significantly different among any of the genotype subgroups. Significantly higher creatinine concentrations were found among recipients with II genotype compared to the combined group of ID and DD among patients not treated with ACE inhibitors, but not among those receiving ACE I after kidney transplantation. No differences were found in the frequency of rejection episodes among the subgroups with different ACE genotypes. No significant influence of donor ACE genotype on renal graft function was observed. In summary, the I/D genotype was not an independent prognostic factor for renal graft survival in the first 4 years after transplantation. Possibly the use of ACE I alters the influence of genotype on some parameters.

Effects of spironolactone on endothelial function, vascular angiotensin converting enzyme activity, and other prognostic markers in patients with mild heart failure already taking optimal treatment

OBJECTIVES

To examine whether the favourable effects on endothelial function, vascular angiotensin converting enzyme (ACE) activity, cardiac remodelling, autonomic function, and QT intervals of spironolactone in combination with ACE inhibitor also occur in patients with New York Heart Association class I-II congestive heart failure (CHF) taking optimal treatment (including beta blockers).

METHODS

Double blind, crossover study comparing 12.5-50 mg/24 hours spironolactone (three months) with placebo in 43 patients with class I-II CHF taking ACE inhibitors and beta blockers.

RESULTS

Acetylcholine induced vasodilatation improved with spironolactone (p = 0.044). Vascular ACE activity fell (p = 0.006). QTc and QTd fell (mean (SD) QTc 473 (43.1) ms with placebo, 455 (35.4) ms with spironolactone, p = 0.002; QTd 84.5 (41.3) ms with placebo, 72.1 (32.3) ms with spironolactone, p = 0.037). beta-Type natriuretic peptide (BNP) and procollagen III N-terminal peptide (PIIINP) concentrations were also reduced by spironolactone (mean (SD) BNP 48.5 (29.6) pg/ml with placebo, 36.8 (28.5) pg/ml with spironolactone, p = 0.039; PIIINP 3.767 (1.157) microg/ml with placebo, 3.156 (1.123) microg/ml with spironolactone, p = 0.000).

CONCLUSIONS

Spironolactone improves vascular function (endothelial function, vascular ACE activity) and other markers of prognosis (BNP, collagen markers, and QT interval length) in asymptomatic or mild CHF when added to optimal treatment including beta blockade. This gives support to the hypothesis that the prognostic benefit seen in RALES (randomised aldactone evaluation study) and EPHESUS (eplerenone postacute myocardial infarction heart failure efficacy and survival study) may also occur in patients with milder CHF already taking standard optimal treatment.

Antihypertensive drug therapy and the risk of lower extremity amputations in pharmacologically treated type 2 diabetes patients

PURPOSE

The objective of this study was to determine the association between different antihypertensive drug therapies and lower extremity amputations (LEAs) in type 2 diabetes patients.

METHODS

Data were obtained from the PHARMO Record Linkage System comprising pharmacy records and data on hospitalisations for all 450,000 residents of eight Dutch cities. In a nested case-control study among 12,140 type 2 diabetes patients who used antihypertensive drugs, 26 cases with a first LEA and 94 controls without a LEA matched on age, sex and calendar time were identified. Logistic regression was used to estimate the relative risk of LEA and to adjust for potential confounding factors.

RESULTS

Among type 2 diabetes patients who used antihypertensive drugs, subjects who used thiazide diuretics, alone or in combination, had a higher risk of LEA compared to subjects who used Angiotensin Converting Enzyme (ACE) inhibitor monotherapy (crude odds ratio (OR): 6.11 [95% confidence interval (CI): 1.32-28.27]). The use of thiazide diuretics was also associated with an increased risk of LEA when compared to the use of any non-thiazide antihypertensive drug (adjusted OR: 7.04 [1.10-45.30]). The increased risk of LEA associated with the use of thiazides compared to the use of non-thiazides depended on the duration of use (adjusted OR(< or = 365 days), 4.82 [0.61-38.34] and adjusted OR(>365 days), 26.16 [1.02-674.02], p-trend = 0.01).

CONCLUSIONS

Treatment with thiazide diuretics compared to treatment with other antihypertensive drugs was associated with excess amputations in type 2 diabetes patients. Due to several limitations of this study, our findings do not preclude the use of thiazides in type 2 diabetes mellitus patients as yet.

[Erythrocytosis post kidney transplantation and its pharmacological treatment: angiotensin converting enzyme inhibitors or angiotensin receptor blockers in a case]

A 35 years old male is presented. Eight months after receiving a renal allograft his hypertension worsened and his packed red cell volume raised to 53.7% Enalapril was started and a 500 ml phlebotomy was performed. In three occasions packed red cell volumes decreased excessively and enalapril was discontinued. Finally, the drug was replaced with losartan, normalizing blood pressure values and stabilizing packed red cell volumes. This case illustrates the different reductions in packed red cell volumes induced by enalapril and losartan. These differences could have a therapeutic relevance.

[Cardiomyopathy induced by catecholamines in neuroblastoma]

BACKGROUND

Cardiovascular disorders associated with neural crest tumors are congenital malformations rather than cardiomyopathies.

CASE REPORT

A 18 month-old girl developed heart failure one week after discovery of an adrenal neuroblastoma with excessive secretion of catecholamines. Investigation showed dilated cardiomyopathy without myocardial hypertrophy. Besides chemotherapy, the patient was given nitrous derivatives, diuretics and converting enzyme inhibitor. His cardiac condition gradually improved so that partial resection of the tumor was possible 2 years later.

CONCLUSIONS

The cardiomyopathy presented by this patient is possibly catecholamine-induced even though catecholamines usually results in myocardial hypertrophy rather than dilated cardiomyopathy. The reason why such a cardiomyopathy has never been reported in patients with neuroblastoma remains unclear.

Patterns of medication use in patients with heart failure: a report from the Registry of Studies of Left Ventricular Dysfunction (SOLVD)

To determine patterns of medication use based on clinical variables in patients with heart failure, we analyzed data from 5,999 patients participating in the Registry of Studies of Left Ventricular Dysfunction (SOLVD). The Registry comprised a broad spectrum of patients with heart failure, including some with predominantly diastolic dysfunction. Drug use was determined in a population cross-sectional manner at the time of identification (74% hospitalized). The median number of drugs per patient was four, with diuretics taken by 62%, digitalis by 45%, angiotensin-converting enzyme inhibitors (ACE-I) by 32%, calcium channel blockers by 36%, antiarrhythmics by 22%, and beta-blockers by 18%. Only 18% were on the combination of ACE-I, diuretic, and digitalis. Stratification for diagnosis, heart failure symptoms, and ejection fractions demonstrated that triple-drug therapy (digitalis, diuretic, and ACE-I) was common only in those with ejection fractions less than .20 and several signs or symptoms of heart failure. Older patients were taking diuretics frequently (73% of patients older than 70 years of age), and our European center used fewer drugs overall, while prescribing digitalis about half as frequently as North American clinics. These data serve as the baseline for analysis of evolving therapeutic practice in patients with heart failure.

The efficacy of monatepil, a new calcium antagonist, in the treatment of essential hypertension

A multicenter, open-label trial in Japan examined the efficacy, safety, and optimal dose of monatepil (AJ-2615) as monotherapy and in combination therapy with angiotensin-converting enzyme (ACE) inhibitors or beta-blockers. Patients with essential hypertension who had never been treated or had been refractory to conventional antihypertensive agents were enrolled in the trial. During a 4-week control period patients assigned to monotherapy received placebo and those assigned to combination therapy received an ACE inhibitor or beta-blocker and placebo. Patients with systolic blood pressure (BP) > or = 160 mm Hg and diastolic BP > or = 95 mm Hg at the end of the control period were enrolled in the study. The initial dose of monatepil was 30 mg/day in monotherapy and 15 mg/day in combination therapy; the daily dose was titrated to 60 mg/day according to the antihypertensive response. The treatment period was 8 to 12 weeks. Blood pressure decreased from 168 +/- 8/100 +/- 6 to 142 +/- 9/85 +/- 7 mm Hg (SD) with monatepil monotherapy, from 171 +/- 11/102 +/- 6 to 141 +/- 9/84 +/- 6 mm Hg in combination with ACE inhibitors, and from 175 +/- 13/102 +/- 7 to 153 +/- 21/91 +/- 9 mm Hg in combination with beta-blockers (P < .001). When patients in whom mean BP decreased by > or = 13 mm Hg were defined as responders, the response rate was 80.4%, 78.1%, and 51.6% in the respective groups.(ABSTRACT TRUNCATED AT 250 WORDS)

The 1980s: a patient-specific therapeutic approach in hypertension

The conventional "stepped-care" approach to the treatment of hypertension deserves revision. Rational therapy considers a variety of factors to obtain maximum efficacy, safety, tolerability, compliance, and neutralization of neural tone for the prevention of sudden death. The patient's age, gender, race, behavior profile, hemodynamic and neurohumoral status (plasma renin activity, norepinephrine/epinephrine ratio), and quality of life will help determine the choice of antihypertensive agent. Concomitant risk factors (smoking, obesity, diabetes, hypercholesterolemia), the presence of sequelae (left ventricular hypertrophy and/or failure, renal failure), and the existence of other disorders (mitral valve prolapse, depression, anxiety) must also be considered when initiating treatment. In addition, the cost of ancillary expenses (laboratory tests, hospitalizations, and emergency room visits) must be weighed against the potential benefits of therapy. Beta blockers are effective, well tolerated, and versatile for the treatment of concomitant cardiovascular disorders and as behavior modifiers. Calcium channel blockers and angiotensin converting enzyme inhibitors also show promise and merit consideration as therapy for specific groups of hypertensive patients.

Regional and systemic metabolic effects of angiotensin-converting enzyme inhibition during exercise in patients with severe heart failure

The acute hemodynamic and metabolic effects of captopril therapy were studied in 12 patients with severe heart failure during maximal exercise performed on an upright bicycle ergometer. During the control period, exhaustion occurred after 4.2 +/- 2.7 minutes of exercise. Cardiac index increased from 1.54 +/- 0.36 l/min/m2 at rest to 3.39 +/- 1.54 l/min/m2 (p less than 0.001) at exhaustion; systemic arteriovenous oxygen difference increased from 8.8 +/- 2.1 to 12.8 +/0 2.4 ml/100 ml (p less than 0.001) and oxygen uptake from 3.4 +/- 0.5 to 10.8 +/- 3.0 ml/kg/min (p less than 0.001). Pulmonary arterial oxygen content decreased from 7.3 +/- 1.3 to 3.7 +/- 1.5 ml/100 ml (p less than 0.001) and femoral vein oxygen content from 5.0 +/- 1.7 to 2.5 +/- 1.2 ml/100 ml (p less than 0.001). During captopril therapy, cardiac index significantly increased both at rest (1.83 +/- 0.54 vs 1.54 +/- 0.36 l/min/m2, p less than 0.01) and during maximal exercise (3.67 +/- 1.51 vs 3.39 +/- 1.54 l/min/m2, p less than 0.01). Systemic arteriovenous oxygen difference decreased significantly at rest, from 8.8 +/- 2.1 to 7.7 +/- 2.1 ml/100 ml (p less than 0.01) and during maximal exercise from 12.8 +/- 2.4 to 12.3 +/- 2.2 ml/100 ml (p less than 0.01). Pulmonary arterial oxygen content at exhaustion was significantly higher during captopril therapy than during the control period (4.1 +/- 1.1 vs 3.7 +/- 1.5 ml/100 ml, p less than 0.05), while femoral venous blood content was unchanged. Captopril therapy did not significantly increase maximal oxygen uptake or exercise duration. Thus, the acute administration of captopril to patients with severe heart failure does not increase exercise capacity despite improved cardiac performance. Moreover, captopril therapy does not acutely result in metabolic benefits to the skeletal muscles during exercise.

Long-term converting enzyme inhibition and sympathetic nerve function in hypertensive humans

Orthostatic hypotension is uncommon during oral converting enzyme inhibition, even when combined with salt depletion. To assess the mechanisms responsible for the cardiovascular homeostasis in this condition, we studied the blood pressure (BP), heart rate (HR), total plasma catecholamines (CA), and plasma renin activity (PRA) responses after 20 minutes of 60 degrees head-up tilt in four groups of hypertensive patients. Group 1 included seven untreated patients; Group 2, eight patients on converting enzyme inhibitor (captopril) therapy; Group 3, six patients on diuretic therapy and Group 4, 15 patients on combined captopril and diuretic therapy. Long-term converting enzyme inhibition alone or in combination with diuretics resulted in reduction of mean arterial pressure (MAP) associated with a marked increase in PRA and fall in plasma aldosterone concentration (PAC). Pronounced increases in HR and plasma CA on tilt were observed in all groups. In Groups 1, 2, and 3, BP was maintained during tilt; in Group 4, three patients fainted between 5 and 15 minutes while the other 12 had a normal response to tilt. Plasma catecholamines increased more significantly after 15 and 20 minutes of tilt, more in Groups 3 and 4 than in Group 1, while no differences in HR response were observed among groups. Results suggest that sympathetic compensatory mechanisms are adequate in the majority of patients to maintain BP during converting enzyme inhibition even when combined with salt depletion. In a few who exhibited orthostatic hypotension, a vasovagal attack seemed to be responsible for bradycardia and fall in BP.