The prognostic importance of the angiotensin II/angiotensin-(1-7) ratio in patients with SARS-CoV-2 infection.

BACKGROUND: Information about angiotensin II (Ang II), angiotensin-converting enzyme 2 (ACE2), and Ang-(1-7) levels in patients with COVID-19 is scarce. OBJECTIVE: To characterize the Ang II-ACE2-Ang-(1-7) axis in patients with SARS-CoV-2 infection to understand its role in pathogenesis and prognosis. METHODS: Patients greater than 18 years diagnosed with COVID-19, based on clinical findings and positive RT-PCR test, who required hospitalization and treatment were included. We compared Ang II, aldosterone, Ang-(1-7), and Ang-(1-9) concentrations and ACE2 concentration and activity between COVID-19 patients and historic controls. We compared baseline demographics, laboratory results (enzyme, peptide, and inflammatory marker levels), and outcome (patients who survived versus those who died). RESULTS: Serum from 74 patients [age: 58 (48-67.2) years; 68% men] with moderate (20%) or severe (80%) COVID-19 were analyzed. During 13 (10-21) days of hospitalization, 25 patients died from COVID-19 and 49 patients survived. Compared with controls, Ang II concentration was higher and Ang-(1-7) concentration was lower, despite significantly higher ACE2 activity in patients. Ang II concentration was higher and Ang-(1-7) concentration was lower in patients who died. The Ang II/Ang-(1-7) ratio was significantly higher in patients who died. In multivariate analysis, Ang II/Ang-(1-7) ratio greater than 3.45 (OR = 5.87) and lymphocyte count ⩽0.65 × 103/µl (OR = 8.43) were independent predictors of mortality from COVID-19. CONCLUSION: In patients with severe SARS-CoV-2 infection, imbalance in the Ang II-ACE2-Ang-(1-7) axis may reflect deleterious effects of Ang II and may indicate a worse outcome.

Alamandine, a derivative of angiotensin-(1-7), alleviates sepsis-associated renal inflammation and apoptosis by inhibiting the PI3K/Ak and MAPK pathways.

Sepsis is a frequent cause of kidney injury. The present study investigated whether Alamandine (Ala) could alleviate sepsis-associated renal injury by reducing inflammation and apoptosis. In addition, we investigated downstream signaling pathways modulated by Ala. Studies were performed in mice treated with lipopolysaccharide (LPS) and in the human proximal tubular epithelial cell line HK-2. The increase in serum creatinine, blood urea nitrogen, cystatin C and Fg, and neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 in the kidneys of mice treated with LPS were reduced after administration of Ala. Exposure to LPS increased interleukin-1 beta (IL-1ß), IL-6, and tumor necrosis factor alpha (TNF-α) in mice and HK-2 cells, but were reduced after Ala treatment. Furthermore, increased levels of cleaved caspase 3, cleaved caspase 7, cleaved caspase 9, cleaved poly (ADP-ribose) polymerase (PARP) and Bax and reduced levels of Bcl2 in LPS-treated mice and HK-2 cells were reversed after Ala administration. In addition, LPS increased the levels of p-PI3K/PI3K, p-Akt/Akt, p-ERK/ERK, p-JNK/JNK, p-p38/p38 and p-FoxO1 in HK-2 cells, and all were reversed after Ala administration. These results indicate that Ala could improve renal function and inhibit inflammation and apoptosis in LPS induced sepsis mouse models. We demonstrated that Ala attenuated LPS induced sepsis by inhibiting the PI3K/Akt and MAPK signaling pathways.

Improved pharmacokinetics and bone tissue accumulation of Angiotensin-(1-7) peptide through bisphosphonate conjugation.

The renin-angiotensin system (RAS) has a central role in renal and cardiovascular homeostasis. Angiotensin-(1-7) (Ang1-7), one of the RAS active peptides, exerts beneficial effects through different mechanisms. These biological actions suggest that Ang1-7 is an effective therapeutic agent for treating various diseases associated with activated RAS. However, its short half-life and poor pharmacokinetics restrict its therapeutic utility. Our laboratory has successfully synthesized and characterized an Ang1-7 conjugate (Ang Conj.) with a prolonged half-life and improved pharmacokinetics profile. The Ang Conj. has been prepared by PEGylation of Ang1-7 and conjugation with a bisphosphonate using solid-phase peptide synthesis and characterized by HPLC and mass spectrometer. The compound's stability has been tested in different storage conditions. The bone binding capacity was evaluated using a hydroxyapatite assay. Pharmacokinetic and tissue distribution studies were performed using iodinated peptides in rats. Ang Conj. was synthesized with > 90% purity. Bone mineral affinity testing showed Ang Conj. exhibited significantly higher bone mineral affinity than Ang1-7. The Ang Conj. remained stable for more than a month using all tested storage conditions. The Ang Conj. demonstrated higher affinity to bone, a longer half-life, and better bioavailability when compared with the native peptide. These results support that conjugation of Ang1-7 with bisphosphonate enables it to utilize bone as a reservoir for the sustained delivery of Ang1-7 to maintain therapeutic plasma levels. High chemical stability and about five to tenfold prolongation of Ang Conj. plasma half-life after administrations into rats proves the effectiveness of our approach.

Synthesis and Biological Evaluation of N-Aminoimidazolidin-2-one-Containing Angiotensin-(1-7) Peptidomimetics.

N-Aminoimidazolidin-2-one (Aid)-containing peptides with a constrained backbone present a novel class of peptidomimetics for drug discovery. The introduction of Aid residues into peptide sequences has been achieved by intramolecular Mitsunobu cyclization of a serine side chain onto the α-NH of an aza-glycine residue. The effectiveness of this new strategy was demonstrated by synthesizing six Aid-containing analogues of angiotensin-(1-7) on solid support. The Aid analogues of angiotensin-(1-7) exhibited increased peptidase stability against human ACE and DPP3 and improved anti-inflammation and antiproliferation activity.

AVE0991, a nonpeptide angiotensin-(1-7) mimic, inhibits angiotensin II-induced abdominal aortic aneurysm formation in apolipoprotein E knockout mice.

AVE0991, a nonpeptide angiotensin-(1-7) mimic, has similar protective effects for cardiovascular system to Ang-(1-7). In this article, we aimed to explore the effects of AVE0991 and Ang-(1-7) on abdominal aortic aneurysm (AAA) induced by Ang II in apolipoprotein E knockout mice. The mice AAA model was established by Ang II infusion, and then mice received different treatment with saline, Ang II (1.44 mg/kg/day), different dose AVE0991 (0.58 or 1.16 µmol/kg/day), or Ang-(1-7) (400 ng/kg/min). The incidence of AAA was 76%, 48%, 28%, and 24% in the vehicle, the low-dose AVE0991, high-dose AVE0991, and the Ang-(1-7) group, respectively. In comparison with control group, AVE0991 and Ang-(1-7) treatment significantly increased smooth muscle cells and decreased macrophage accumulation, the expression levels of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor α (TNF-α), and the expression and activity of metalloproteinases 2 and 9 in mice AAA model or in human smooth muscle cells (hVSMCs). The therapeutic effects may be contributed to reduction of oxidative stress and downregulation of P38 and ERK1/2 signal pathways via Mas receptor activation, whereas the positive impacts were reversed by co-administration with the Mas antagonist A779 (400 ng/kg/min) and AVE0991 in Ang II-infused mice or in hVSMCs. Therefore, AVE0991 and Ang-(1-7) might be novel and promising interventions in the prevention and treatment of AAA. KEY MESSAGES: • AVE0991 dose-dependently inhibited Ang II-induced AAA formation in Apoe-/- mice. • Ang-(1-7) played the same protective role as high-dose AVE0991. • Inhibition of Mas receptor with A779 could reverse the protective effect of AVE0991. • The therapeutic effects may be contributed to reduction of oxidative stress and downregulation of P38 and ERK1/2 signal pathways via Mas receptor activation.

Addition of cyclic angiotensin-(1-7) to angiotensin-converting enzyme inhibitor therapy has a positive add-on effect in experimental diabetic nephropathy.

The Renin-Angiotensin System (RAS) possesses a counter-regulatory axis composed of angiotensin converting enzyme (ACE)2, angiotensin-(1-7) [Ang-(1-7)] and the Mas receptor, which opposes many AT1-receptor-mediated effects of ligand angiotensin II. Ang-(1-7), as a ligand of the Mas receptor, has inhibitory effects on renal inflammation and fibrosis in experimental diabetes. However, Ang-(1-7) has a short half-life in plasma, which may render it unsuitable for use in clinics. Here, we investigated the effects of the lanthionine-stabilized Ang-(1-7), cyclic (c)Ang-(1-7), a lanthipeptide that is more peptidase-resistant than the linear peptide, in BTBR ob/ob mice with type 2 diabetic nephropathy. BTBR ob/ob mice received vehicle, cAng-(1-7), or the ACE inhibitor lisinopril. The treatment started at ten weeks of age, when the animals had already developed albuminuria, and ended at 19-20 weeks of age. cAng-(1-7) limited albuminuria progression, and limited podocyte dysfunction similarly to lisinopril. cAng-(1-7), unlike lisinopril, reduced glomerular fibrosis and inflammation, and counteracted glomerular capillary rarefaction. Furthermore, when cAng-(1-7) was combined with lisinopril, a superior antiproteinuric effect than with lisinopril alone was found, in association with better preservation of podocyte proteins and amelioration of capillary density. Thus, adding cAng-(1-7) to ACE-inhibitor therapy could benefit those diabetic patients who do not respond completely to ACE-inhibitor therapy.

Superoxide anions mediate the effects of angiotensin (1-7) analog, alamandine, on blood pressure and sympathetic activity in the paraventricular nucleus.

Microinjection of alamandine into the hypothalamic paraventricular nucleus (PVN) increased blood pressure and enhanced sympathetic activity. The aim of this study was to determine if superoxide anions modulate alamandine's effects in the PVN. Mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) were recorded in anaesthetized normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). Microinjection of alamandine into the PVN increased MAP and RSNA in both WKY rats and SHRs, although to a greater extent in SHRs. These effects were blocked by pretreatment with an alamandine receptor (MrgD) antagonist D-Pro7-Ang-(1-7). Pretreatment with superoxide anion scavengers, tempol and tiron, and NADPH oxidase inhibitor apocynin (APO), also blocked the effects of alamandine on MAP and RSNA. In addition, pretreatment in the PVN with a superoxide dismutase (SOD) inhibitor diethyldithiocarbamic acid (DETC) potentiated the increases of MAP and RSNA induced by alamandine administration, with a greater response observed in SHRs. Superoxide anions and NADPH oxidase levels in the PVN were higher in SHRs than that in WKY rats. Alamandine treatment increased the levels of superoxide anions and NADPH oxidase in WKY and SHRs, however, with greater effect in SHRs. These alamandine-induced increases were inhibited by D-Pro7-Ang-(1-7) pretreatment in the PVN of both rats. These results demonstrate that superoxide anions in the PVN modulate alamandine-induced increases in blood pressure and sympathetic activity in both normotensive and hypertensive rats. Alamandine increases NADPH oxidase activity to induce superoxide anion production, which is mediated by the alamandine receptor.

Influenza A virus mimetic nanoparticles trigger selective cell uptake.

Poor target cell specificity is currently a major shortcoming of nanoparticles (NPs) used for biomedical applications. It causes significant material loss to off-target sites and poor availability at the intended delivery site. To overcome this limitation, we designed particles that identify cells in a virus-like manner. As a blueprint, we chose a mechanism typical of influenza A virus particles in which ectoenzymatic hemagglutinin activation by target cells is a mandatory prerequisite for binding to a secondary target structure that finally confirms cell identity and allows for uptake of the virus. We developed NPs that probe mesangial cells for the presence of angiotensin-converting enzyme on their surface using angiotensin I (Ang-I) as a proligand. This initial interaction enzymatically transforms Ang-I to a secondary ligand angiotensin II (Ang-II) that has the potential to bind in a second stage to Ang-II type-1 receptor (AT1R). The presence of the receptor confirms the target cell identity and triggers NP uptake via endocytosis. Our virus-mimetic NPs showed outstanding target-cell affinity with picomolar avidities and were able to selectively identify these cells in the presence of 90% off-target cells that carried only the AT1R. Our results demonstrate that the design of virus-mimetic cell interactive NPs is a valuable strategy to enhance NP specificity for therapeutic and diagnostic applications. Our set of primary and secondary targets is particularly suited for the identification of mesangial cells that play a pivotal role in diabetic nephropathy, one of the leading causes of renal failure, for which currently no treatment exists.

Circulating angiotensin peptides levels in Acute Respiratory Distress Syndrome correlate with clinical outcomes: A pilot study.

RATIONALE: We propose renin angiotensin system (RAS) peptides are critical in wound reparative processes such as in acute respiratory distress syndrome (ARDS). Their role in predicting clinical outcomes in ARDS has been unexplored; thus, we used a targeted metabolomics approach to investigate them as potential predictors of outcomes. METHODS: Thirty-nine ARDS patients were enrolled within 24 hours of ARDS diagnosis. Plasma RAS peptide levels were quantified at study entry and 24, 48 and 72 hours using a liquid chromatography-mass spectrometry based metabolomics assay. RAS peptide concentrations were compared between survivors and non-survivors, and were correlated with clinical and pulmonary measures. MEASUREMENTS AND MAIN RESULTS: Angiotensin I (Ang-I or A(1-10)) levels were significantly higher in non-survivors at study entry and 72 hours. ARDS survival was associated with lower A(1-10) concentration (OR 0.36, 95% CI 0.18-0.72, p = 0.004) but higher A(1-9) concentration (OR 2.24, 95% CI 1.15-4.39, p = 0.018), a biologically active metabolite of A(1-10) and an agonist of angiotensin II receptor type 2. Survivors had significantly higher median A(1-9)/A(1-10) and A(1-7)/A(1-10) ratios than the non-survivors (p = 0.001). Increased A(1-9)/A(1-10) ratio suggests that angiotensin converting enzyme II (ACE2) activity is higher in patients who survived their ARDS insult while an increase in A(1-7)/A(1-10) ratio suggests that ACE activity is also higher in survivors. CONCLUSION: A(1-10) accumulation and reduced A(1-9) concentration in the non-survivor group suggest that ACE2 activities may be reduced in patients succumbing to ARDS. Plasma levels of both A(1-10) and A(1-9) and their ratio may serve as useful biomarkers for prognosis in ARDS patients.

A Novel Angiotensin-(1-7) Glycosylated Mas Receptor Agonist for Treating Vascular Cognitive Impairment and Inflammation-Related Memory Dysfunction.

Increasing evidence indicates that decreased brain blood flow, increased reactive oxygen species (ROS) production, and proinflammatory mechanisms accelerate neurodegenerative disease progression such as that seen in vascular contributions to cognitive impairment and dementia (VCID) and Alzheimer's disease and related dementias. There is a critical clinical need for safe and effective therapies for the treatment and prevention of cognitive impairment known to occur in patients with VCID and chronic inflammatory diseases such as heart failure (HF), hypertension, and diabetes. This study used our mouse model of VCID/HF to test our novel glycosylated angiotensin-(1-7) peptide Ang-1-6-O-Ser-Glc-NH2 (PNA5) as a therapy to treat VCID and to investigate circulating inflammatory biomarkers that may be involved. We demonstrate that PNA5 has greater brain penetration compared with the native angiotensin-(1-7) peptide. Moreover, after treatment with 1.0/mg/kg, s.c., for 21 days, PNA5 exhibits up to 10 days of sustained cognitive protective effects in our VCID/HF mice that last beyond the peptide half-life. PNA5 reversed object recognition impairment in VCID/HF mice and rescued spatial memory impairment. PNA5 activation of the Mas receptor results in a dose-dependent inhibition of ROS in human endothelial cells. Last, PNA5 treatment decreased VCID/HF-induced activation of brain microglia/macrophages and inhibited circulating tumor necrosis factor α, interleukin (IL)-7, and granulocyte cell-stimulating factor serum levels while increasing that of the anti-inflammatory cytokine IL-10. These results suggest that PNA5 is an excellent candidate and "first-in-class" therapy for treating VCID and other inflammation-related brain diseases.

A Fast Photochemical Oxidation of Proteins (FPOP) platform for free-radical reactions: the carbonate radical anion with peptides and proteins.

Fast Photochemical Oxidation of Protein (FPOP), based on a pulsed KrF laser (248 nm) for free-radical generation, is a biophysical method that utilizes hydroxyl radicals to footprint proteins in solution. FPOP has been recognized for structural proteomics investigations, including epitope mapping, protein-aggregation characterization, protein-folding monitoring, and binding-affinity determination. The distinct merits of the platform are: i) the use of a scavenger to control radical lifetime and allow fast ("snapshot") footprinting of solvent-accessible residues in a protein; ii) the employment of a flow system to enable single-shot irradiation of small plugs of the targeted sample; iii) the use of methionine and catalase after radical oxidation chemistry to prevent post-oxidation with residual oxidizing species; and iv) the utilization of mature mass spectrometry-based proteomic methods to afford detailed analysis. In addition to •OH, other reactive reagents (e.g., carbenes, iodide, sulfate radical anion, and trifluoromethyl radical) can be implemented on this platform to increase the versatility and scope. In this study, we further elaborate the use of FPOP platform to generate secondary radicals and establish a workflow to answer fundamental questions regarding the intrinsic selectivity and reactivity of radicals that are important in biology. Carbonate radical anion is the example we chose owing to its oxidative character and important putative pathogenic roles in inflammation. This systematic study with model proteins/peptides gives consistent results with a previous study that evaluated reactivity with free amino acids and shows that methionine and tryptophan are the most reactive residues with CO3-•. Other aromatic amino acids (i.e., tyrosine, histidine and phenylalanine) exhibit moderate reactivity, whereas, aliphatic amino acids are inert, unlike with •OH. The outcome demonstrates this approach to be appropriate for studying the fast reactions of radicals with proteins.

Efficacy of lanthionine-stabilized angiotensin-(1-7) in type I and type II diabetes mouse models.

Native angiotensin-(1-7) exerts many therapeutic effects. However, it is rapidly degraded by ACE and other peptidases. This drawback is largely eliminated for lanthionine-stabilized angiotensin-(1-7), termed cAng-(1-7), which is fully resistant to ACE and has strongly increased resistance to other peptidases. Goal of the present study was to test whether cAng-(1-7) has therapeutic activity in diabetes mouse models: in a multiple low dose streptozotocin-induced model of type I diabetes and / or in a db/db model of type II diabetes. In the type I diabetes model cAng-(1-7) caused in an increase in the insulin level of 133% in week 4 (p < 0.001) compared to vehicle, and in the type II diabetes model an increase of 55% of the insulin level in week 8 (p < 0.05) compared to vehicle. cAng-(1-7) reduced blood glucose levels in the type I model by 37% at day 22 (p < 0.001) and in the type II diabetes model by 17% at day 63 of treatment (p < 0.001) and in an oral glucose tolerance test in a type II diabetes model, by 17% at week 4 (p < 0.01). cAng-(1-7) also caused a reduction of glycated hemoglobin levels in the type II diabetes model of 21% in week 6 (p < 0,001). These data are consistent with therapeutic potential of cAng-(1-7) in type I and II diabetes.

His-Leu, an angiotensin I-derived peptide, does not affect haemodynamics in rats.

INTRODUCTION:: The dipeptide histidine-leucine (His-Leu) is formed in the process of converting angiotensin I into angiotensin II. Several studies show that short peptides containing His-Leu may produce significant haemodynamic effects; however, to the best of our knowledge, data on haemodynamic effects of His-Leu are not available in medical databases. MATERIALS AND METHODS:: We evaluated acute haemodynamic effects of intravenous administration of either 0.9% NaCl (vehicle) or His-Leu at a dose of 3-15 mg/kg body weight in anaesthetized 15-16-week-old, male, normotensive Wistar Kyoto and spontaneously hypertensive rats. Chronic effects of treatment with either the vehicle or His-Leu at a dose of 15 mg/kg body weight given subcutaneously daily were determined during continuous telemetry recordings in freely moving rats. RESULTS:: In anaesthetized rats both the vehicle and His-Leu produced a mild and transient increase in blood pressure and no change in plasma renin activity. There was no significant difference in haemodynamics between the rats infused with the vehicle and the rats infused with His-Leu. In chronic studies, seven-day treatment with vehicle and with His-Leu did not affect arterial blood pressure in freely moving rats. CONCLUSION:: His-Leu does not produce either acute or chronic changes in arterial blood pressure in normotensive and hypertensive rats.

Zeise's salt as powerful platinating agent for proteins investigated by top-down-mass spectrometry.

Metallodrugs have become an integral part of modern medicinal chemistry with platinum drugs as anti-cancer agents being well-known examples. The historically interesting compound Zeise's salt, potassium trichlorido(ethene)platinate(II) has scarcely been investigated in this context yet. This study is geared towards shedding light on the biological reactivity of this platinum complex. Mass Spectrometry tools were used to obtain a deeper understanding of its interactions with biomolecules on the molecular level. Angiotensin I and Ubiquitin were chosen as model systems. Comparison to Cisplatin show that Zeise's salt is more reactive towards nucleophilic sites in proteins. Our data indicate that the ethylene ligand remains on the platinum when coordinated to a nitrogen donor in the biomolecule and therefore offers a linkage for the introduction of further functionality. When attached to sulfur donors in the biomolecule, platinum(II) provides a site for the formation of crosslinks and loops in the biomolecules by losing all four of its initial ligands.

Concomitant desalting and concentration of neuropeptides on a donut-shaped surface pattern for MALDI mass spectrometry.

We demonstrate that a donut-shaped surface pattern consisting of a central hydrophobic region and a surrounding hydrophilic region simultaneously concentrates and desalts a solution of neuropeptides with a high salt content. Our approach greatly simplifies the sample preparation process for MALDI mass spectrometry.

Acetylation and Amination Protect Angiotensin 1-7 from Physiological Hydrolyzation and Therefore Increases Its Antitumor Effects on Lung Cancer.

The recently reported inhibitory effects of angiotensin 1-7 (Ang-(1-7)) on various cancers indicate its potential use as a therapeutic agent for primary and metastatic cancers. However, its extremely short half-life in the circulation greatly compromises its potential applications. Here, we reported an Ang-(1-7) analogue peptide with the amino and carboxy termini protected by acetylation and amination. The in vitro and in vivo degradation of the resulting analogue, Ang-AA, were determined using high-performance liquid chromatography (HPLC). At the same time, small RNA interference and competition studies were performed to evaluate the specific capacity of Ang-AA to bind to the cell surface Mas receptor. Cell Counting Kit-8 (CCK8), wound-healing, and Boyden chamber assays were performed to investigate the inhibitory effects of Ang-AA on A549 cells. Finally, the synergistic inhibitory effects of Ang-AA and paclitaxel (PTX) on A549 xenografts in mice were observed using animal imaging systems and survival observations. The toxicity of Ang-AA in mice was evaluated. Our results showed that acetylation and amination significantly inhibited the hydrolyzation of Ang-(1-7) in vitro and in vivo. The half-life of Ang-(1-7) in rats was prolonged from 2.4 ± 0.6 min to 238.7 ± 61.3 min ( p < 0.001). The specific binding of Ang-AA to the Mas receptor was well preserved, and Ang-AA exerted significantly greater inhibitory effects on the proliferation, migration, and invasion of A549 cells than Ang-(1-7). The combination of Ang-AA and PTX exhibited a significantly greater synergistic inhibitory effect on A549 xenografts than the combination of Ang-(1-7) and PTX. Ang-AA did not display obvious toxicity in mice. Our findings indicate acetylation and amination is a simple and effective method for producing Ang-(1-7) as a bioactive peptide.

Stabilization of Angiotensin-(1-7) by key substitution with a cyclic non-natural amino acid.

Angiotensin-(1-7) [Ang-(1-7)], a heptapeptide hormone of the renin-angiotensin-aldosterone system, is a promising candidate as a treatment for cancer that reflects its anti-proliferative and anti-angiogenic properties. However, the peptide's therapeutic potential is limited by the short half-life and low bioavailability resulting from rapid enzymatic metabolism by peptidases including angiotensin-converting enzyme (ACE) and dipeptidyl peptidase 3 (DPP 3). We report the facile assembly of three novel Ang-(1-7) analogues by solid-phase peptide synthesis which incorporates the cyclic non-natural δ-amino acid ACCA. The analogues containing the ACCA substitution at the site of ACE cleavage exhibit complete resistance to human ACE, while substitution at the DDP 3 cleavage site provided stability against DPP 3 hydrolysis. Furthermore, the analogues retain the anti-proliferative properties of Ang-(1-7) against the 4T1 and HT-1080 cancer cell lines. These results suggest that ACCA-substituted Ang-(1-7) analogues which show resistance against proteolytic degradation by peptidases known to hydrolyze the native heptapeptide may be novel therapeutics in the treatment of cancer.

Isolation and characterization of renin-like aspartic-proteases from Echis ocellatus venom.

Three aspartic proteases (SVAPs) have been isolated from venom of the saw-scaled viper, Echis ocellatus. In confirmation of prior transcriptomic predictions, all three forms match to sequences of either of the two SVAP transcripts (EOC00051 and EOC00123), have a molecular weight of 42 kDa and possess a single N-glycan. The SVAPs act in a renin-like manner, specifically cleaving human and porcine angiotensinogen into angiotensin-1 and possess no general protease activity. Their activity is completely inhibited by the aspartyl protease inhibitor Pepstatin A.

Renin-angiotensin system in ventilator-induced diaphragmatic dysfunction: Potential protective role of Angiotensin (1-7).

Ventilator-induced diaphragmatic dysfunction is a feared complication of mechanical ventilation that adversely affects the outcome of intensive care patients. Human and animal studies demonstrate atrophy and ultrastructural alteration of diaphragmatic muscular fibers attributable to increased oxidative stress, depression of the anabolic pathway regulated by Insulin-like growing factor 1 and increased proteolysis. The renin-angiotensin system, through its main peptide Angiotensin II, plays a major role in skeletal muscle diseases, mainly increasing oxidative stress and inducing insulin resistance, atrophy and fibrosis. Conversely, its counter-regulatory peptide Angiotensin (1-7) has a protective role in these processes. Recent data on rodent models show that renin-angiotensin system is activated after mechanical ventilation and that infusion of Angiotensin II induces diaphragmatic skeletal muscle atrophy. Given: (A) common pathways shared by ventilator-induced diaphragmatic dysfunction and skeletal muscle pathology induced by renin-angiotensin system, (B) evidences of an involvement of renin-angiotensin system in diaphragm atrophy and dysfunction, we hypothesize that renin-angiotensin system plays an important role in ventilator-induced diaphragmatic dysfunction, while Angiotensin (1-7) can have a protective effect on this pathological process. The activation of renin-angiotensin system in ventilator-induced diaphragmatic dysfunction can be demonstrated by quantification of its main components in the diaphragm of ventilated humans or animals. The infusion of Angiotensin (1-7) in an established rodent model of ventilator-induced diaphragmatic dysfunction can be used to test its potential protective role, that can be further confirmed with the infusion of Angiotensin (1-7) antagonists like A-779. Verifying this hypothesis can help in understanding the processes involved in ventilator-induced diaphragmatic dysfunction pathophysiology and open new possibilities for its prevention and treatment.