A single dose of angiotensin-(1-7) resolves eosinophilic inflammation and protects the lungs from a secondary inflammatory challenge.

OBJECTIVE: Angiotensin-(1-7) [Ang-(1-7)] is a pro-resolving mediator. It is not known whether the pro-resolving effects of Ang-(1-7) are sustained and protect the lung from a subsequent inflammatory challenge. This study sought to investigate the impact of treatment in face of a second allergic or lipopolysaccharide (LPS) challenge. METHODS: Mice, sensitized and challenged with ovalbumin (OVA), received a single Ang-(1-7) dose at the peak of eosinophilic inflammation, 24 h after the final OVA challenge. Subsequently, mice were euthanized at 48, 72, 96, and 120 h following the OVA challenge, and cellular infiltrate, inflammatory mediators, lung histopathology, and macrophage-mediated efferocytic activity were evaluated. The secondary inflammatory stimulus (OVA or LPS) was administered 120 h after the last OVA challenge, and subsequent inflammatory analyses were performed. RESULTS: Treatment with Ang-(1-7) resulted in elevated levels of IL-10, CD4+Foxp3+, Mres in the lungs and enhanced macrophage-mediated efferocytic capacity. Moreover, in allergic mice treated with Ang-(1-7) and then subjected to a secondary OVA challenge, inflammation was also reduced. Similarly, in mice exposed to LPS, Ang-(1-7) effectively prevented the lung inflammation. CONCLUSION: A single dose of Ang-(1-7) resolves lung inflammation and protect the lung from a subsequent inflammatory challenge highlighting its potential therapeutic for individuals with asthma.

Asthma: role of the angiotensin-(1-7)/Mas (MAS1) pathway in pathophysiology and therapy.

The incidence of asthma is a global health problem and requires studies aimed for the development of new treatments to improve its clinical management, reducing personal and economic burdens on the health system. Therefore, the discovery of mediators that promote anti-inflammatory and pro-resolutive effects are highly desirable to improve lung function and quality of life of asthmatic patients. In that regard, experimental studies have shown that the angiotensin-(1-7)/Mas receptor (MAS1) of the renin-angiotensin system is a potential candidate for the treatment of asthma. Therefore, we have reviewed findings related to the function of the angiotensin-(1-7)/Mas pathway in regulating the processes associated with inflammation, including leukocyte influx, fibrogenesis, pulmonary dysfunction and the resolution of inflammation in asthma. Thus, a knowledge of the role of the angiotensin-(1-7)/Mas can help pave the way for the development of new treatments for this disease, which has high morbidity and mortality, through new types of experiments and clinical trials.

Angiotensin-(1-7)/Mas receptor modulates anti-inflammatory effects of exercise training in a model of chronic allergic lung inflammation.

AIMS: Exercise training increases circulating and tissue levels of angiotensin-(1-7) [Ang-(1-7)], which was shown to attenuate inflammation and fibrosis in different diseases. Here, we evaluated whether Ang-(1-7)/Mas receptor is involved in the beneficial effects of aerobic training in a chronic model of asthma. MATERIAL AND METHODS: BALB/c mice were subjected to a protocol of asthma induced by ovalbumin sensitization (OVA; 4 i.p. injections) and OVA challenge (3 times/week for 4 weeks). Simultaneously to the challenge period, part of the animals was continuously treated with Mas receptor antagonist (A779, 1 µg/h; for 28 days) and trained in a treadmill (TRE; 60% of the maximal capacity, 1 h/day, 5 days/week during 4 weeks). PGC1-α mRNA expression (qRT-PCR), plasma IgE and lung cytokines (ELISA), inflammatory cells infiltration (enzymatic activity assay) and airway remodeling (by histology) were evaluated. KEY FINDINGS: Blocking the Mas receptor with A779 increased IgE and IL-13 levels and prevented the reduction in extracellular matrix deposition in airways in OVA-TRE mice. Mas receptor blockade prevented the reduction of myeloperoxidase activity, as well as, prevented exercise-induced IL-10 increase. These data show that activation of Ang-(1-7)/Mas receptor pathway is involved in the anti-inflammatory and anti-fibrotic effects of aerobic training in an experimental model of chronic asthma. SIGNIFICANCE: Our results support exercise training as a non-pharmacological tool to defeat lung remodeling induced by chronic pulmonary inflammation. Further, our result also supports development of new therapy based on Ang-(1-7) or Mas agonists as important tool for asthma treatment in those patients that cannot perform aerobic training.

Oral Formulation of Angiotensin-(1-7) Promotes Therapeutic Actions in a Model of Eosinophilic and Neutrophilic Asthma.

The presence of eosinophils and neutrophils in the lungs of asthmatic patients is associated with the severity of the disease and resistance to corticosteroids. Thus, defective resolution of eosinophilic and neutrophilic inflammation is importantly related to exacerbation of asthma. In this study, we investigated a therapeutic action of angiotensin-(1-7) (Ang-(1-7)) in a model of asthma induced by ovalbumin (OVA) and lipopolysaccharide (LPS). Balb-c mice were sensitized and challenged with OVA. Twenty-three hours after the last OVA challenge, experimental groups received LPS, and 1 h and 7 h later, mice were treated with oral formulation of Ang-(1-7). On the next day, 45 h after the last challenge with OVA, mice were subjected to a test of motor and exploratory behavior; 3 h later, lung function was evaluated, and bronchoalveolar lavage fluid (BALF) and lungs were collected. Motor and exploratory activities were lower in OVA + LPS-challenged mice. Treatment with Ang-(1-7) improved these behaviors, normalized lung function, and reduced eosinophil, neutrophil, myeloperoxidase (MPO), eosinophilic peroxidase (EPO), and ERK1/2 phosphorylation (p-ERK1/2) in the lungs. In addition, Ang-(1-7) decreased the deposition of mucus and extracellular matrix in the airways. These results extended those of previous studies by demonstrating that oral administration of Ang-(1-7) at the peak of pulmonary inflammation can be valuable for the treatment of neutrophil- and eosinophil-mediated asthma. Therefore, these findings potentially provide a new drug to reverse the natural history of the disease, unlike the current standards of care that manage the disease symptoms at best.

Treatment with inhaled formulation of angiotensin-(1-7) reverses inflammation and pulmonary remodeling in a model of chronic asthma.

Asthma is characterized by inflammation, pulmonary remodeling and bronchial hyperresponsiveness. We have previously shown that treatment with angiotensin-(1-7) [Ang-(1-7)] promotes resolution of eosinophilic inflammation and prevents chronic allergic lung inflammation. Here, we evaluated the effect of treatment with the inclusion compound of Ang-(1-7) in hydroxypropyl ß-cyclodextrin (HPßCD) given by inhalation on pulmonary remodeling in an ovalbumin (OVA)-induced chronic allergic lung inflammation. Mice were sensitized to ovalbumin (OVA; 4 injections over 42 days, 14 days apart) and were challenged 3 times per week, for 4 weeks (days 21-46). After the 2nd week of challenge, mice were treated with Ang-(1-7) by inhalation (4.5 µg of Ang-(1-7) included in 6.9 µg of HPßCD for 14 days, i.e. days 35-48). Mice were killed 72 h after the last challenge and blood, bronchoalveolar lavage fluid (BALF) and lungs were collected. Histology and morphometric analysis were performed in the lung. Metalloproteinase (MMP)-9 and MMP-12 expression and activity, IL-5, CCL11 in the lung and plasma IgE were measured. After 2 weeks of OVA challenge there was an increase in plasma IgE and in inflammatory cells infiltration in the lung of asthmatic mice. Treatment with inhaled administration of Ang-(1-7)/HPßCD for 14 days reduced eosinophils, IL5, CCL11 in the lung and plasma IgE. Treatment of asthmatic mice with Ang-(1-7)/HPßCD by inhalation reversed pulmonary remodeling by reducing collagen deposition and MMP-9 and MMP-12 expression and activity. These results show for the first time that treatment by inhalation with Ang-(1-7) can reverse an installed asthma, inhibiting pulmonary inflammation and remodeling.

Oral formulation angiotensin-(1-7) therapy attenuates pulmonary and systemic damage in mice with emphysema induced by elastase.

Angiotensin-(1-7) [Ang-(1-7)], a peptide of the renin-angiotensin system, has anti-inflammatory, anti-fibrotic and antiproliferative effects in acute or chronic inflammatory disease of respiratory system. In this study, we evaluated the effect of treatment with Ang-(1-7) on pulmonary tissue damage and behavior of mice submitted to experimental model of elastase-induced pulmonary emphysema (PE). Initially, male C57BL/6 mice were randomly assigned into two main groups: control (CTRL) and PE. In the PE group, the animals received three intratracheal instillations of pancreatic porcine elastase (PPE) at 1-week intervals (0.2 IU in 50 µL of saline). The CTRL group received the same volume of saline solution (50 µL). Twenty-four hours after the last instillation, animals of the PE group were randomly divided into two groups: PE and PE + Ang-(1-7). The PE + Ang-(1-7) group was treated with 60 µg/kg of Ang-(1-7) and 92 µg kg of HPßCD in gavage distilled water, 100 µl. The CTRL and PE groups were treated with vehicle (HPßCD- 92 µg/kg in distilled water per gavage, 100 µl), orally daily for 3 weeks. On the 19th day of treatment, all groups were tested in relation to locomotor activity and exploratory behavior. After 48 h, the animals were euthanized and lungs were collected. The animals of PE group presented rupture of alveolar walls and consequently reduction of alveolar tissue area. Treatment with Ang-(1-7) partially restored the alveolar tissue area. The PE reduced the locomotor activity and the exploratory behavior of the mice in relation to the control group. Treatment with Ang-(1-7) attenuated this change. In addition, it was observed that Ang-(1-7) reduced lung levels of IL-1ß and increased levels of IL-10. These results show an anti-inflammatory effect of Ang-(1-7), inducing the return of pulmonary homeostasis and attenuation of the behavioral changes in experimental model of PE by elastase.