Angiotensin-converting enzyme inhibitors in heart failure: new strategies justified by recent clinical trials

Ecklonia stolonifera Okamura Extract Suppresses Myocardial Infarction-Induced Left Ventricular Systolic Dysfunction by Inhibiting p300-HAT Activity

Ecklonia stolonifera Okamura extract (ESE) has been reported to have various bioactive effects, but its effects on cardiovascular disease have not yet been investigated. First, primary neonatal rat cultured cardiomyocytes were treated with ESE and stimulated with phenylephrine (PE) for 48 h. ESE (1000 µg/mL) significantly suppressed PE-induced cardiomyocyte hypertrophy, hypertrophy-related gene transcription, and the acetylation of histone H3K9. An in vitro p300-HAT assay indicated that ESE directly inhibited p300-HAT activity. Next, one week after myocardial infarction (MI) surgery, rats (left ventricular fractional shortening (LVFS) < 40%) were randomly assigned to three groups: vehicle (saline, n = 9), ESE (0.3 g/kg, n = 10), or ESE (1 g/kg, n = 10). Daily oral administration was carried out for 8 weeks. After treatment, LVFS was significantly higher in the ESE (1 g/kg) group than in the vehicle group. The ESE treatments also significantly suppressed MI-induced increases in myocardial cell diameter, perivascular fibrosis, hypertrophy- and fibrosis-related gene transcription, and the acetylation of histone H3K9. These results suggest that ESE suppressed both hypertrophic responses in cardiomyocytes and the development of heart failure in rats by inhibiting p300-HAT activity. Thus, this dietary extract is a potential novel therapeutic strategy for heart failure in humans.

Captopril inhibits matrix metalloproteinase activity and improves dentin bonding durability

OBJECTIVES

We investigated the inhibitory effects of captopril on matrix metalloproteinases (MMPs) and its effect as a primer on dentin bonding durability.

MATERIALS AND METHODS

One hundred fifty human third molars were selected. Flat surfaces of the middle dentin were exposed, etched 15 s, and followed by pretreatment with a primer for 60 s, including distilled water (control, the negative control primer), 2% chlorhexidine digluconate (CHD, the positive control primer), and captopril solution. Inhibitory effects of primers on MMPs were evaluated by hydroxyproline and gelatinase activity tests. All primers were applied on dentin followed by bonding. Some of the samples were sliced into slabs, placed in a fluorescent solution containing gelatin, and incubated for in situ zymography. Some were cut into sticks, and after aging for 1 day, 12 months, or 24 months, microtensile bonding strength was tested. Some were cut into slabs, aged for 1 day, 12 months, or 24 months, and taken out for nanoleakage tests to reveal interface defects.

RESULTS

Hydroxyproline and gelatinase activity analyses showed that captopril exerted better inhibitory effects on MMPs, relative to 2% CHD (p < 0.05). A 0.2% captopril aqueous solution (0.2% CapW) was chosen to apply to the dentin. In situ zymography showed that inhibitory effects of captopril on gelatinase were significantly higher compared to 2% CHD (p < 0.01). Microtensile strength revealed that the bonding effects of the 0.2% CapW group lasted longer, compared to the control and 2% CHD groups (p < 0.05). Interface defects, detected by nanoleakage, were significantly reduced in the 0.2% CapW group, compared to the control and 2% CHD groups (p < 0.05).

CONCLUSIONS

Captopril inhibits dentin MMP activities and effectively improves dentin bonding durability.

CLINICAL RELEVANCE

Captopril is a promising dentin bonding primer for improving bonding durability.

Curcumin and its demethoxy derivatives possess p300 HAT inhibitory activity and suppress hypertrophic responses in cardiomyocytes

The natural compound, curcumin (CUR), possesses several pharmacological properties, including p300-specific histone acetyltransferase (HAT) inhibitory activity. In our previous study, we demonstrated that CUR could prevent the development of cardiac hypertrophy by inhibiting p300-HAT activity. Other major curcuminoids isolated from Curcuma longa including demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC) are structural analogs of CUR. In present study, we first confirmed the effect of these three curcuminoid analogs on p300-HAT activity and cardiomyocyte hypertrophy. Our results showed that DMC and BDMC inhibited p300-HAT activity and cardiomyocyte hypertrophy to almost the same extent as CUR. As the three compounds have structural differences in methoxy groups at the 3-position of their phenol rings, our results suggest that these methoxy groups are not involved in the inhibitory effects on p300-HAT activity and cardiac hypertrophy. These findings provide useful insights into the structure-activity relationship and biological activity of curcuminoids for p300-HAT activity and cardiomyocyte hypertrophy.

ACE Inhibition versus Angiotensin-II Antagonism in Heart Failure

Heart failure is becoming increasingly frequent. Once diagnosed, 5-year survival is less than 50% and a substantial percentage of patients (25% to 50%) die suddenly. Angiotensin-converting enzyme inhibitors are the only agents shown to reduce mortality in heart failure. All angiotensin-converting enzyme inhibitors appear to have similar clinical benefits in heart failure. Therapy should be started with a low dose and titrated up to the target dosage in major trials. Although angiotensin-I receptor antagonists provide more complete inhibition of angiotensin-II effects, they have not been found to be superior to long-acting angiotensin-converting enzyme inhibitors in reducing morbidity and mortality in heart failure. Therefore, in current clinical practice, angiotensin-II antagonists should be used as an alternative to angiotensin-converting enzyme inhibitors when the latter are not tolerated. The combined use of angiotensin-converting enzyme inhibitors and angiotensin-II antagonists is not currently recommended in the treatment of heart failure.

Current treatment in acute and chronic cardio-renal syndrome

Cardio-renal syndrome (CRS) is a renal dysfunction occurring in a large percentage of patients hospitalized with congestive heart failure (HF). Cardiac and renal dysfunctions often occur simultaneously because they share causes and pathogenetic mechanisms. Current therapies for HF are focused on improving myocardial function and hemodynamic balance, but may have potential consequences for worsening renal function. The lack of specific trials in this field highlights the need for further studies aimed to assess efficacy and safety, titration and appropriate dosages of drugs, according to the etiology and severity of both myocardial and renal dysfunction. Moreover, the most recent clinical trials evaluating new drugs on clinical and renal outcome in acute heart failure syndromes (AHFS) failed to demonstrate an improvement in renal function and perfusion. In this context, several questions regarding the priority of drugs, their recommended dosage and potential adverse effects on cardiac and renal outcome need to be addressed. Although clinical guidelines for managing both HF and chronic kidney disease (CKD) have been drawn, until now agreed guidelines about patients with cardio-renal and reno-cardiac syndromes are lacking. Future treatment directions should take into consideration both kidney and heart function. Only this comprehensive approach might lead to an improvement in the management and outcomes of patients affected by CRS.

A natural p300-specific histone acetyltransferase inhibitor, curcumin, in addition to angiotensin-converting enzyme inhibitor, exerts beneficial effects on left ventricular systolic function after myocardial infarction in rats

BACKGROUND

A natural p300-specific histone acetyltransferase (HAT) inhibitor, curcumin, may have therapeutic potential for heart failure. However, it is unclear whether curcumin exhibits beneficial additive or synergistic effects on conventional therapy with angiotensin-converting enzyme inhibitors (ACEIs).

METHODS AND RESULTS

Rats were subjected to a sham operation or left coronary artery ligation. One week later, 34 rats with a moderate sized myocardial infarction (MI) were randomly assigned to 4 groups: solvents as control (n = 8), enalapril (an ACEI, 10 mg·kg⁻¹·day⁻¹) alone (n=8), curcumin (50 mg·kg⁻¹·day⁻¹) alone (n = 9) and enalapril plus curcumin (n = 9). Daily oral treatment was repeated and continued for 6 weeks. Echocardiographic data were similar among the 4 groups before treatment. After treatment, left ventricular (LV) fractional shortening (FS) was significantly higher in the enalapril (29.0 ± 1.9%) and curcumin (30.8 ± 1.7%) groups than in the vehicle group (19.7 ± 1.6%). Notably, LVFS further increased in the enalapril/curcumin combination group (34.4 ± 1.8%). Histologically, cardiomyocyte diameter in the non-infarct area was smaller in the enalapril/curcumin combination group than in the enalapril group. Perivascular fibrosis was significantly reduced in the enalapril/curcumin group compared with the curcumin group.

CONCLUSIONS

A natural non-toxic dietary compound, curcumin, combined with an ACEI exerts beneficial effects on post-MI LV systolic function in rats.

Captopril, an Angiotensin-Converting Enzyme Inhibitor, Promotes Growth of Immunogenic Tumors in Mice

PURPOSE

Antitumor potential of angiotensin-converting enzyme inhibitors has been shown in different preclinical settings, which always involved immunocompromised organisms or nonimmunogenic tumor models. In our study, we wanted to evaluate the effect of captopril on growth of immunogenic tumors in immunocompetent animals.

EXPERIMENTAL DESIGN

We used different murine tumor models to evaluate the effect of captopril on tumor take and survival of tumor-bearing immunocompetent and immunocompromised mice. We used an orthotopic renal cell cancer model and highly immunogenic tumor model, which were based on kidney subcapsular injection of RenCa cells or s.c. injection of MethA cells, respectively. To show the influence of captopril on antigen-specific immune responses, we have used two model antigens (green fluorescent protein and beta-galactosidase).

RESULTS

Captopril decreased survival of RenCa-bearing, immunocompetent mice in a dose-dependent manner and in adjuvant setting. In nephrectomized mice, captopril shortened their survival. Captopril promoted formation of immunogenic MethA sarcoma tumors but had no effect on nonimmunogenic melanoma cells (B78-H1). Treatment of immunocompromised mice bearing MethA tumors or RenCa kidney tumors with captopril did not affect tumor formation nor survival, respectively. Captopril-treated mice immunized with AdLacZ or AdGFP vectors did not generate or generated decreased numbers of antigen-specific CD8+ T cells, respectively. However, they showed B-cell responses represented by infiltration of MethA tumors with activated B cells and dramatically increased serum level of beta-galactosidase-specific antibodies.

CONCLUSIONS

Our results show a novel role of captopril in tumor biology and the tumor-promoting properties of captopril seem to be associated with its immunomodulatory potential.

Pharmacoeconomic considerations in assessing and selecting congestive heart failure therapies

Over the last two decades the incidence of congestive heart failure (CHF) has increased with aging of the population and in spite of the decline in age-adjusted mortality rates due to coronary heart disease. Its management has seen substantial progress, embodied in the introduction of ACE inhibitors, initially as part of triple therapy in which they complemented diuretics and digoxin, and latterly as first-line therapy. The current consensus on treatment of CHF has been based on the multiple clinical studies performed with ACE inhibitors in which these agents have been shown to prevent a new cardiovascular accident and/or progression to more severe CHF in an increasingly wide range of patients with symptomatic CHF or post-infarction left ventricular dysfunction (ejection fraction </= 40% in some trials or </= 35% in others). Not only have the results shown a marked decrease in all-cause (and especially cardiovascular) mortality, but also a great number of cost-effectiveness analyses have shown the advantages of ACE inhibitors in terms of resource allocation: they are either cost saving or convincingly cost effective compared with standard treatment with digoxin and diuretics. Other drugs require similar cost and clinical analyses before they can earn their place in an add-on strategy. To date, cost savings have been documented only for beta-blockers; implantable devices are still undergoing assessment. Two trends are now competing: one is to downplay add-on strategies and to recommend first-line therapy with ACE inhibitors and beta-blockers at effective doses, supplemented by a raft of non-pharmaceutical measures (specialist nurses, patient education, dietary advice, exercise) in a multidisciplinary approach to CHF; the second is, on the contrary, to prescribe up to five drugs for patients with advanced CHF. The evidence that this decreases hospital admission rates and patient cost is more than anecdotal, but conclusive proof of cost effectiveness is still lacking and the approach presupposes dedicated structures. This review argues that despite technical limitations, a combined approach of CHF therapy based on clinical trials and cost-effectiveness analyses is essential. However, improvements can be made. The absence of sufficient comparative data still makes it difficult to choose between drugs within the same class; institutional purchasers need to conduct such analyses to identify the drugs best suited to their patients' profiles and budgetary constraints.

Ambulatory heart failure management in private practice in France

Management of ambulatory heart failure was assessed in a group of 600 patients, mean age 73, 64% males, NYHA I: 9%; II: 52%; III: 33%; IV: 6%; followed up by a representative sample of private cardiologists. Fifty-two percent of patients had been previously hospitalised for worsening heart failure with a mean duration of stay of 13.1 days, for those hospitalised in the year preceding the survey (26%). First diagnosis of heart failure had been performed by a cardiologist (57%), a general practitioner (37%) or another category of physician (6%). Seventy percent of patients received three or more different classes of heart failure medications. Diuretics were prescribed to 71%, angiotensin converting enzyme inhibitors to 54% and digitalis to 35% of the population. Beta-blockers were given to only 14% of the patients. In patients aged over 80 years, only 45% received angiotensin converting enzyme inhibitors.

CONCLUSION

This survey of ambulatory heart failure patients confirms that the disease is predominantly observed in elderly patients, and associated with prolonged and recurrent hospitalisations. The underuse of recommended therapeutic classes including angiotensin converting enzyme inhibitors and beta-blockers deserves further investigation.

Captopril modulates hormone receptor concentration and inhibits proliferation of human mammary ductal carcinoma cells in culture

The present study evaluated the effect of the angiotensin converting enzyme (ACE) inhibitor captopril on estrogen (ER) and progesterone (PR) receptor concentration and on proliferation in two lines of human mammary ductal carcinoma cells in culture: T-47D (ER+/PR+) and Hs578T (ER-/PR-). The incorporation of [3H]thymidine, validated by cell count, served as an index of proliferation. Compared to control cells, T-47D cells incubated for 48 hrs in 1, 2, or 5 mM captopril (but not in 0.5 mM) exhibited a reduction in ER from 130 +/- 6 to 32 +/- 32 fmol/mg cytosolic protein, and an increase in PR from 1780 +/- 120 to 2740 +/- 400 fmol/ mg protein (p < 0.05). Western analysis confirmed these drug-induced changes in the concentration of immunoreactive receptor proteins. Captopril also induced the appearance of low but detectable PR in the Hs578T cells at concentrations as low as 50 microM. Captopril inhibited the incorporation of [3H]thymidine by both cell types during a 48 hr incubation, although Hs578T cells were 2-3 times more resistant than were T-47D cells. This cytostatic effect of captopril was not due to cytotoxicity as indicated by 51Cr release, and was not accompanied by significant changes in cell cycle distribution as determined by flow cytometry. The incorporation of [3H]uridine (RNA synthesis) and [14C]alanine (protein synthesis) also were inhibited by captopril, suggesting a general antimetabolic effect of the drug in the ductal carcinoma cells. These are novel actions of a common antihypertensive agent. In contrast, the nonthiol ACE inhibitor lisinopril, and penicillamine, a thiol compound with virtually no ACE inhibitory activity, had no effect on any of these endpoints.

What is the role of angiotensin-converting enzyme inhibitors in congestive heart failure and after myocardial infarction?

OBJECTIVE

To discuss the controversies surrounding the choice of angiotensin-converting enzyme (ACE) inhibitor, and the timing, dosage, and duration of ACE inhibitor therapy for congestive heart failure (CHF) and after myocardial infarction (MI). The beneficial effects of ACE inhibition in patients with CHF and after MI are reviewed. Human clinical trials are reviewed and their clinical implications are discussed.

DATA SOURCES

MEDLINE searches (1985-1995) identified human clinical trials and review articles.

DATA EXTRACTION

Landmark human clinical trials with morbidity and mortality end points were included. The validity of the study data were assessed on the basis of study methods, population characteristics, and statistical power.

DATA SYNTHESIS

ACE inhibitors exert beneficial effects in patients with CHF by hemodynamic and neurohormonal mechanisms. The attenuation of ventricular remodeling that occurs with ACE inhibition does not fully explain the results of clinical trials in patients after MI. Routine determination of ejection fraction to guide ACE inhibitor therapy is not as important as the patient's clinical status. Clinicians should titrate the chosen ACE inhibitor on the basis of hemodynamic response to target doses used in major clinical trials. Because the beneficial effects of ACE inhibitors appear to be a class effect, choice of an agent should include cost considerations and the results of clinical trials.

CONCLUSIONS

ACE inhibitor reduce morbidity and mortality in selected CHF and post-MI patients. Patients with symptomatic CHF benefit most from ACE inhibitor therapy, and it should be continued indefinitely. Treatment effects in asymptomatic patients are delayed. The role of ACE inhibitor therapy in preventing morbidity and morality in asymptomatic patients with preserved ventricular function requires further study.

Captopril inhibits angiogenesis and slows the growth of experimental tumors in rats

Captopril, an inhibitor of angiotensin converting enzyme, is widely used clinically to manage hypertension and congestive heart failure. Here captopril is shown to be an inhibitor of angiogenesis able to block neovascularization induced in the rat cornea. Captopril acted directly and specifically on capillary endothelial cells, inhibiting their chemotaxis with a biphasic dose-response curve showing an initial decrease at clinically achievable doses under 10 microM and a further slow decline in the millimolar range. Captopril inhibition of endothelial cell migration was not mediated by angiotensin converting enzyme inhibition, but was suppressed by zinc. Direct inhibition by captopril of zinc-dependent endothelial cell-derived 72-and 92-kD metalloproteinases known to be essential for angiogenesis was also seen. When used systemically on rats captopril inhibited corneal neovascularization and showed the antitumor activity expected of an inhibitor of angiogenesis, decreasing the number of mitoses present in carcinogen-induced foci of preneoplastic liver cells and slowing the growth rate of an experimental fibrosarcoma whose cells were resistant to captopril in vitro. These data define this widely used drug as a new inhibitor of neovascularization and raise the possibility that patients on long term captopril therapy may derive unexpected benefits from its antiangiogenic activities.

Contemporary management of patients with heart failure

Treatment of patients with heart failure has become extremely challenging. A complicated interplay of myocardial, hemodynamic, and humoral factors marking this condition requires a delicate balancing of medication use, procedural intervention, and lifestyle changes. Judicious prescription of therapies in stepwise fashion as the syndrome severity worsens (Fig. 2) is critical to success.

New directions in the treatment of heart failure: some paradoxical observations

The alpha-agonist drug phenylephrine has been generally considered to be contraindicated in patients with heart failure for the reason that increased afterload produced by the vasoconstriction should decrease ventricular function; the beta-adrenergic blocking drugs generally have been considered to be contraindicated in heart failure because of the dependence of the failing heart on beta-sympathetic agonism; the angiotensin converting enzyme inhibitors have been indicted recently as causing undesirable cardiovascular depression in patients for coronary artery bypass surgery. Yet recently, phenylephrine has been shown to have positive cardiac inotropic effects in a variety of experimental preparations including intact humans; the beta-adrenergic blocking drugs have been shown to be therapeutically effective in treating patients with chronic congestive heart failure (CHF); and the "gold standard" for treating chronic CHF at present are the ACEI. Consequently, the clinician caring for patients with cardiac disease needs to reevaluate the use of classic drugs whose original pharmacological properties may either have changed because of advances in technology or may be producing effects that were unanticipated previously.