Association of an oral formulation of angiotensin-(1-7) with atenolol improves lipid metabolism in hypertensive rats

Acute and Chronic Pretreatment With Atenolol Attenuates Intestinal Ischemia and Reperfusion Injury in Hypercholesterolemic Rats

OBJECTIVE

To evaluate the protective effects of preinjury atenolol (acute v chronic) on apoptosis, contractility, oxidative stress, and inflammatory markers in hypercholesterolemic rats undergoing intestinal ischemia-reperfusion (I/R) injury.

DESIGN

Prospective, experimental animal study.

SETTING

University laboratory.

PARTICIPANTS

Male Wistar rats (n = 32).

INTERVENTIONS

Rats were divided into the following 4 groups: 1 group was fed a normal diet (ND) (group ND+NoAT [no atenolol]), and the other 3 groups were fed a high-cholesterol diet (HCD)-group HCD+NoAT, group HCD+ChAT (chronic atenolol, 3 mg/kg/day for 8 weeks), and group HCD+AcAT (acute atenolol, 1.5 mg/kg, given 5 minutes before intestinal clamping). All rats underwent I/R injury. The superior mesenteric artery was clamped for 60 minutes, then opened for 120 minutes (reperfusion). Apoptotic cells and stimulated contractions of ileal segments were examined. Tissue markers of intestinal I/R injury were examined. Intestinal malondialdehyde, superoxide dismutase, and nitrate/nitrite levels were measured.

MEASUREMENTS AND MAIN RESULTS

The chronic atenolol group had fewer apoptotic cells and higher superoxide dismutase activity compared with the other groups. Intestinal contraction was higher in both atenolol pretreatment groups compared with the NoAT groups. Chronic and acute atenolol resulted in lower ileal levels of malondialdehyde and immunolabeling-positive cells (intestinal inducible nitric oxide synthase, endothelial nitric oxide synthase, interleukin-1, and interleukin-8) after I/R injury compared with the no atenolol groups.

CONCLUSIONS

Both chronic and acute pre-I/R injury treatment with atenolol attenuated I/R injury in this hypercholesterolemic rat model. These findings should encourage future studies of atenolol in hypercholesterolemic patients undergoing procedures with a high risk of intestinal ischemia.

Therapeutic uses for Angiotensin-(1-7)

INTRODUCTION

Angiotensin-(1-7) is a key component of the Renin-Angiotensin System, which can counter-regulate several deleterious effects caused by angiotensin II. Due to the potential for therapeutic use, several of its actions are specifically described in patents.

AREAS COVERED

In this review, the authors describe a plethora of therapeutic uses for Angiotensin-(1-7), claimed and supported by experimental evidence in patent documents and applications.

EXPERT OPINION

The clinical potential of Angiotensin-(1-7) as a therapeutic agent to treat several pathologies is evidenced by the variety of patents and clinical trials involving this peptide. Cancer treatment is one of the most advanced therapeutic areas, but clinical studies are also available in several other areas, such as cardiovascular, hematological, transplantation, surgical and medical procedures.

ACE inhibition, ACE2 and angiotensin-(1-7) axis in kidney and cardiac inflammation and fibrosis

The Renin Angiotensin System (RAS) is a pivotal physiological regulator of heart and kidney homeostasis, but also plays an important role in the pathophysiology of heart and kidney diseases. Recently, new components of the RAS have been discovered, including angiotensin converting enzyme 2 (ACE2), Angiotensin(Ang)-(1-7), Mas receptor, Ang-(1-9) and Alamandine. These new components of RAS are formed by the hydrolysis of Ang I and Ang II and, in general, counteract the effects of Ang II. In experimental models of heart and renal diseases, Ang-(1-7), Ang-(1-9) and Alamandine produced vasodilation, inhibition of cell growth, anti-thrombotic, anti-inflammatory and anti-fibrotic effects. Recent pharmacological strategies have been proposed to potentiate the effects or to enhance the formation of Ang-(1-7) and Ang-(1-9), including ACE2 activators, Ang-(1-7) in hydroxypropyl β-cyclodextrin, cyclized form of Ang-(1-7) and nonpeptide synthetic Mas receptor agonists. Here, we review the role and effects of ACE2, ACE2 activators, Ang-(1-7) and synthetic Mas receptor agonists in the control of inflammation and fibrosis in cardiovascular and renal diseases and as counter-regulators of the ACE-Ang II-AT1 axis. We briefly comment on the therapeutic potential of the novel members of RAS, Ang-(1-9) and alamandine, and the interactions between classical RAS inhibitors and new players in heart and kidney diseases.

Angiotensin-(1-7) attenuates airway remodelling and hyperresponsiveness in a model of chronic allergic lung inflammation

BACKGROUND AND PURPOSE

A long-term imbalance between pro- and anti-inflammatory mediators leads to airway remodelling, which is strongly correlated to most of the symptoms, severity and progression of chronic lung inflammation. The Angiotensin-(1-7) [Ang-(1-7)]/Mas receptor axis of the renin-angiotensin system is associated with attenuation of acute and chronic inflammatory processes. In this study, we investigated the effects of Ang-(1-7) treatment in a model of chronic allergic lung inflammation.

EXPERIMENTAL APPROACH

Mice were sensitized to ovalbumin (OVA; 4 injections over 42 days, 14 days apart) and were challenged three times per week (days 21-46). These mice received Ang-(1-7) (1 μg·h(-1) , s.c.) by osmotic mini-pumps, for the last 28 days. Histology and morphometric analysis were performed in left lung and right ventricle. Airway responsiveness to methacholine, analysis of Ang-(1-7) levels (RIA), collagen I and III (qRT-PCR), ERK1/2 and JNK (Western blotting), IgE (elisa), cytokines and chemokines (elisa multiplex), and immunohistochemistry for Mas receptors were performed.

KEY RESULTS

Infusion of Ang-(1-7) in OVA-sensitized and challenged mice decreased inflammatory cell infiltration and collagen deposition in the airways and lung parenchyma, and prevented bronchial hyperresponsiveness. These effects were accompanied by decreased IgE and ERK1/2 phosphorylation, and decreased pro-inflammatory cytokines. Mas receptors were detected in the epithelium and bronchial smooth muscle, suggesting a site in the lung for the beneficial actions of Ang-(1-7).

CONCLUSIONS AND IMPLICATIONS

Ang-(1-7) exerted beneficial attenuation of three major features of chronic asthma: lung inflammation, airway remodelling and hyperresponsiveness. Our results support an important protective role of Ang-(1-7) in lung inflammation.