ACE-inhibition ameliorates vascular reactivity and delays diabetes outcome in NOD mice

Effects of Zofenopril on Arterial Stiffness in Hypertension Patients

Angiotensin-converting enzyme inhibitors (ACEIs) reduce arterial stiffness beyond their antihypertensive effect. Studies showed that sulfhydryl ACEIs have the antioxidative potential to improve endothelial function, which might have a clinical effect on arterial distensibility. However, there are no studies that directly compare the effects of sulfhydryl (zofenopril) and non-sulfhydryl ACEIs (enalapril) on arterial stiffness. Therefore, this prospective study aims to compare the effects of enalapril and zofenopril on arterial stiffness and oxidative stress in both short- and long-term treatment of arterial hypertension (AH). Baseline and post-treatment peripheral and central arterial pressure indices, augmentation index (Aix), aortic pulse wave velocity (ao-PWV), serum levels of oxidized low-density cholesterol lipoprotein, LDL and uric acid (UA) were measured. The results showed that acute treatment with zofenopril, in contrast to enalapril, significantly decreased peripheral and central Aix (p < 0.001). Chronic treatment with zofenopril showed a superior effect over enalapril on the reduction of the peripheral systolic arterial pressure with reduction of ao-PWV (p = 0.004), as well as a reduction in peripheral Aix (p = 0.021) and central Aix (p = 0.021). Therefore, this study indicates that zofenopril has beneficial effects on the reduction of arterial stiffness compared to enalapril. It has potent clinical efficacy in AH treatment and further studies should compare its safety and long-term efficacy to other AH drugs that would aid clinicians in treating AH and other various cardiovascular diseases that have arterial stiffness as a common denominator.

Hydrogen sulfide donor AP123 restores endothelial nitric oxide-dependent vascular function in hyperglycemia via a CREB-dependent pathway

Diabetes is associated with severe vascular complications involving the impairment of endothelial nitric oxide synthase (eNOS) as well as cystathionine γ-lyase (CSE) activity. eNOS function is suppressed in hyperglycaemic conditions, resulting in reduced NO bioavailability, which is paralleled by reduced levels of hydrogen sulfide (H₂S). Here we have addressed the molecular basis of the interplay between the eNOS and CSE pathways. We tested the impact of H₂S replacement by using the mitochondrial-targeted H₂S donor AP123 in isolated vessels and cultured endothelial cells in high glucose (HG) environment, at concentrations not causing any vasoactive effect per se. Aorta exposed to HG displayed a marked reduction of acetylcholine (Ach)-induced vasorelaxation that was restored by the addition of AP123 (10 nM). In HG condition, bovine aortic endothelial cells (BAEC) showed reduced NO levels, downregulation of eNOS expression, and suppression of CREB activation (p-CREB). Similar results were obtained by treating BAEC with propargylglycine (PAG), an inhibitor of CSE. AP123 treatment rescued eNOS expression, as well as NO levels, and restored p-CREB expression in both the HG environment and the presence of PAG. This effect was mediated by a PI3K-dependent activity since wortmannin (PI3K inhibitor) blunted the rescuing effects operated by the H₂S donor. Experiments performed in the aorta of CSE^-/- mice confirmed that reduced levels of H₂S not only negatively affect the CREB pathway but also impair Ach-induced vasodilation, significantly ameliorated by AP123. We have demonstrated that the endothelial dysfunction due to HG involves H₂S/PI3K/CREB/eNOS route, thus highlighting a novel aspect of the H₂S/NO interplay in the vasoactive response.

Hydrogen sulfide and vascular regulation - An update

BACKGROUND

Hydrogen sulfide (H₂S) is considered to be the third gasotransmitter after carbon monoxide (CO) and nitric oxide (NO). It plays an important role in the regulation of vascular homeostasis. Vascular remodeling have has proved to be related to the impaired H₂S generation.

AIM OF REVIEW

This study aimed to summarize and discuss current data about the function of H₂S in vascular physiology and pathophysiology as well as the underlying mechanisms.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Endogenous hydrogen sulfide (H₂S) as a third gasotransmitter is primarily generated by the enzymatic pathways and regulated by several metabolic pathways. H₂S as a physiologic vascular regulator, inhibits proliferation, regulates its apoptosis and autophagy of vascular cells and controls the vascular tone. Accumulating evidence shows that the downregulation of H₂S pathway is involved in the pathogenesis of a variety of vascular diseases, such as hypertension, atherosclerosis and pulmonary hypertension. Alternatively, H₂S supplementation may greatly help to prevent the progression of the vascular diseases by regulating vascular tone, inhibiting vascular inflammation, protecting against oxidative stress and proliferation, and modulating vascular cell apoptosis, which has been verified in animal and cell experiments and even in the clinical investigation. Besides, H₂S system and angiotensin-converting enzyme (ACE) inhibitors play a vital role in alleviating ischemic heart disease and left ventricular dysfunction. Notably, sulfhydryl-containing ACEI inhibitor zofenopril is superior to other ACE inhibitors due to its capability of H₂S releasing, in addition to ACE inhibition. The design and application of novel H₂S donors have significant clinical implications in the treatment of vascular-related diseases. However, further research regarding the role of H₂S in vascular physiology and pathophysiology is required.

Fixed-dose combination of zofenopril plus hydrochlorothiazide vs. irbesartan plus hydrochlorothiazide in hypertensive patients with established metabolic syndrome uncontrolled by previous monotherapy. The ZAMES study (Zofenopril in Advanced MEtabolic Syndrome)

OBJECTIVE

Whether all antihypertensive drugs are equally effective in patients with metabolic syndrome is still unclear. The goal of the Zofenopril in Advanced MEtabolic Syndrome (ZAMES) study was to investigate whether treatment with the fixed-dose combination of sulphydril-containing angiotensin-converting enzyme inhibitor zofenopril plus hydrochlorothiazide is at least as effective as that with the angiotensin receptor blocker irbesartan plus hydrochlorothiazide in patients with metabolic syndrome and essential hypertension, uncontrolled by a previous monotherapy.

METHODS

We enrolled 721 patients in a multicenter, international (Italy and Romania), randomized, double-blind, parallel group, phase III study. Following a 1-week screening withdrawal period, 482 patients (mean age 59 ± 10 years, 53% men) bearing a SBP at least 140 mmHg and/or DBP at least 90 mmHg plus metabolic syndrome (ATP-III criteria) were randomly allocated to a fixed-dose combination of zofenopril 30 mg plus hydrochlorothiazide 12.5 mg or irbesartan 150 mg plus hydrochlorothiazide 12.5 mg once daily for a cumulative period of 24 weeks. After 8 and 16 weeks, zofenopril and irbesartan doses were doubled in nonnormalized study participants. The study endpoint was the office DBP reduction at study end. In 20% of patients, an ambulatory blood pressure monitoring was performed.

RESULTS

The prevalence of diabetes at baseline was significantly (P < 0.05) greater in the zofenopril plus hydrochlorothiazide group (82%) than in the irbesartan plus hydrochlorothiazide (73%) group. Baseline-adjusted DBP reductions were superimposable (P = 0.370) with zofenopril plus hydrochlorothiazide [n = 231; 9.8 (95% confidence interval: 11.1, 8.4) mmHg] and irbesartan plus hydrochlorothiazide [n = 235; 10.4 (11.8, 9.0) mmHg]. The same was for SBP [17.0 (19.2, 14.8) mmHg zofenopril plus hydrochlorothiazide vs. 18.8 (21.0, 16.6) mmHg irbesartan plus hydrochlorothiazide, P = 0.113]. Rate of normalized and responder patients (SBP/DBP < 140/90 mmHg or SBP reduction more than 20 mmHg or DBP reduction more than 10 mmHg) did not differ at study end (65.8% and 77.5% zofenopril plus hydrochlorothiazide vs. 67.7% and 81.5% irbesartan plus hydrochlorothiazide; P = 0.695, P = 0.301). These results were confirmed in the 69 study participants undergoing ambulatory blood pressure monitoring (35 zofenopril plus hydrochlorothiazide; 34 irbesartan plus hydrochlorothiazide), with a comparable 24-h average BP reduction [BP difference between-treatment: SBP: 0.1 (-5.7, 5.9) mmHg, P = 0.975; DBP: -0.9 (-3.8, 2.0) mmHg, P = 0.541]. Both drugs attained similar BP reductions also in the last 6 h of the dosing interval [between-treatment difference SBP: 0.1 (-7.4, 7.5) mmHg P = 0.990; DBP: -0.9 (-4.4, 2.6) mmHg, P = 0.602]. Metabolic and renal indexes were not altered. Few patients were withdrawn for moderate adverse events (5% zofenopril plus hydrochlorothiazide; 5% irbesartan plus hydrochlorothiazide).

CONCLUSION

This is the first study supporting the comparable antihypertensive and metabolic response to fixed-dose combinations of sulphydril-containing angiotensin-converting enzyme inhibitors (zofenopril) or angiotensin receptor blockers (Irbesartan) with a diuretic in patients with advanced metabolic syndrome and nonresponders to monotherapy. The results of this study can further improve the clinical management of high cardiovascular risk patients with hypertension and metabolic syndrome, because these two drug combinations increase the number of available combinations, which may significantly improve patients' adherence in this special clinical condition that is frequently found in everyday practice.

Vascular effects of linagliptin in non-obese diabetic mice are glucose-independent and involve positive modulation of the endothelial nitric oxide synthase (eNOS)/caveolin-1 (CAV-1) pathway

AIM

To test the effect of linagliptin in non-obese diabetic (NOD) mice, a murine model of type 1 diabetes, to unveil a possible direct cardiovascular action of dipeptidyl peptidase 4 (DPP-4) inhibitors beyond glycaemia control.

METHODS

NOD mice were grouped according to glycosuria levels as NODI: none; NODII: high; NODIII: severe. Linagliptin treatment was initiated once they reached NODII levels. Vascular reactivity was assessed ex vivo on aorta harvested from mice upon reaching NODIII level. In a separate set of experiments, the effect of linagliptin was tested directly in vitro on vessels harvested from untreated NODIII, glucagon-like peptide-1 (GLP-1) receptor knockout and soluble guanylyl cyclase-α1 knockout mice. Molecular and cellular studies were performed on endothelial and endothelial nitric oxide synthase (eNOS)-transfected cells.

RESULTS

In this ex vivo vascular study, endothelium-dependent vasorelaxation was ameliorated and eNOS/nitric oxide (NO)/soluble guanylyl cyclase (sGC) signalling was enhanced. In the in vitro vascular study, linagliptin exerted a direct vasodilating activity on vessels harvested from both normo- or hyperglycaemic mice. The effect was independent from GLP-1/GLP-1 receptor (GLP-1R) interaction and required eNOS/NO/sGC pathway activation. Molecular studies performed on endothelial cells show that linagliptin rescues eNOS from caveolin-1 (CAV-1)-binding in a calcium-independent manner.

CONCLUSION

Linagliptin, by interfering with the protein-protein interaction CAV-1/eNOS, led to an increased eNOS availability, thus enhancing NO production. This mechanism accounts for the vascular effect of linagliptin that is independent from glucose control and GLP-1/GLP-1R interaction.

Safety and efficacy of the sulfydryl ACE-inhibitor zofenopril in the management of cardiovascular disease

In the 1970s, pharmacological therapy interrupting the renin-angiotensin system was considered beneficial for patients with high-renin hypertension. Angiotensin-converting enzyme (ACE) inhibitors proved to be effective not only in patients with high renin and elevated blood pressure, but also in many hypertensive patients with normal levels of plasma renin activity. ACE inhibitors are used in a wide range of chronic illnesses such as atherosclerosis, hypertension, myocardial infarction, heart failure, diabetic complications, and stroke. To date, more than ninety controlled clinical trials evaluating the beneficial effects of 14 different ACE inhibitors were conducted. Moreover, data from experimental studies showed that ACE inhibitors can attenuate the development of atherosclerosis, oxidative stress, and vascular inflammation in a wide range of species indicating that ACE inhibition also favourably affects the vasculature. More than fifteen years ago, the bi-sulfydryl ACE-inhibitor zofenopril has shown an excellent clinical safety and efficacy in patients with hypertension and in those with myocardial infarction. More recently, this compound exhibited a potent antioxidant and antiatherosclerotic effect indicating a clinical useful vasoprotective action.

Effect of captopril and the bradykinin-PKC pathway on ROS production in type 1 diabetic rats

The aim of this study was to investigate the possible effects of captopril as a promoter in modulating the oxidant-antioxidant balance in rats with type 1 diabetes, and the influence of protein kinase C (PKC) pathways in the production of reactive oxygen species (ROS) induced by bradykinin in type 1 diabetic rats. This study evaluated the redox status in both the cardiac tissue and at the cellular level (neutrophils). Two concentrations of captopril were utilized: (i) 5 mg·(kg body mass)(-1), which was considered a therapeutic dose; and (ii) 10 mg·(kg body mass)(-1). Body mass, plasma glucose, and serum insulin were evaluated. To investigate the redox status of the cardiac tissue, we analyzed lipid peroxidation, concentration of carbonylated protein, catalase activity, and the concentration of glutathione. For a more accurate assessment of the possible antioxidant effect of captopril, we also analyzed ROS in neutrophils (in vivo), and ROS production induced by bradykinin and the influence of the PKC pathway in this production (in vitro). Our data show that the hearts of diabetic animals have increased oxidative damage, exemplified by the increased concentration of carbonylated protein and thiobarbituric acid reactive substances (TBARS). However, animals treated with captopril at both concentrations showed lower concentrations of carbonylated protein compared with untreated diabetic animals. We found an increase of catalase activity in the heart of diabetic rats, which was reversed by captopril treatment at both of the dosages tested. Our data showed that captopril was able to reduce ROS production in the neutrophils of diabetic rats at a dose of 10 mg captopril·(kg body mass)(-1). However, the antioxidant effect of captopril is independent of bradykinin. Diabetes induces oxidative stress, and these results suggest that captopril has an antioxidant effect and can modulate the production of ROS in circulating neutrophils.

Angiotensin II type 1 receptor-dependent oxidative stress mediates endothelial dysfunction in type 2 diabetic mice

The mechanisms underlying the effect of the renin-angiotensin-aldosterone system (RAAS) inhibition on endothelial dysfunction in type 2 diabetes are incompletely understood. This study explored a causal relationship between RAAS activation and oxidative stress involved in diabetes-associated endothelial dysfunction. Daily oral administration of valsartan or enalapril at 10 mg/kg/day to db/db mice for 6 weeks reversed the blunted acetylcholine-induced endothelium-dependent dilatations, suppressed the upregulated expression of angiotensin II type 1 receptor (AT(1)R) and NAD(P)H oxidase subunits (p22(phox) and p47(phox)), and reduced reactive oxygen species (ROS) production. Acute exposure to AT(1)R blocker losartan restored the impaired endothelium-dependent dilatations in aortas of db/db mice and also in renal arteries of diabetic patients (fasting plasma glucose level > or =7.0 mmol/l). Similar observations were also made with apocynin, diphenyliodonium, or tempol treatment in db/db mouse aortas. DHE fluorescence revealed an overproduction of ROS in db/db aortas which was sensitive to inhibition by losartan or ROS scavengers. Losartan also prevented the impairment of endothelium-dependent dilatations under hyperglycemic conditions that were accompanied by high ROS production. The present study has identified an initiative role of AT(1)R activation in mediating endothelial dysfunction of arteries from db/db mice and diabetic patients.