Long-Term Administration of Angiotensin (1-7) to db/db Mice Reduces Oxidative Stress Damage in the Kidneys and Prevents Renal Dysfunction

Losartan is more effective than angiotensin (1-7) in preventing thyroxine-induced renal injury in the rat

AIM

Studies have shown that renal hypertrophy seen in experimental hyperthyroidism induced by thyroxine (T4) is due to angiotensin (Ang) II. However, other renal effects of Ang II in experimental hyperthyroidism have not been investigated. In addition, Ang 1-7 is believed to be protective against renal injury, but its possible role in thyroxine-induced renal injury is not known. The aim of this study is to elaborate the role of Ang II in thyroxine-induced renal injury and the possible protective role of Ang 1-7. We hypothesize that Ang 1-7 will be as protective against thyroxine-induced renal injury as the use of an ACE inhibitor or an Ang II receptor blocker.

METHODS

Adult Sprague Dawley rats were used in this study and were divided into 5 groups: (1) Control (treated with vehicle), (2) Treated with thyroxine (T4, 100 µg/kg), (3) Treated with T4 and Ang 1-7 (500 µg/kg), (4) Treated with T4 and captopril (20 mg/kg), and (5) Treated with T4 and losartan (10 mg/kg). Parameters tested after fourteen days of treatment were creatinine clearance, protein excretion rate, glomerular volume, renal ACE1 and ACE2 protein expression. Data were compared using One-way-ANOVA followed by Tukey's HSD post hoc test.

RESULTS

Thyroxine caused glomerular hypertrophy and proteinuria but had no effect on glomerular filtration rate (GFR). Glomerular hypertrophy was prevented by losartan and captopril, but not by Ang 1-7. Captopril and losartan had no effect on GFR; however, Ang 1-7 caused an increase in GFR in T4-treated rats. The increase in protein excretion rate was prevented by losartan but not by captopril or Ang 1-7. Renal expression of ACE1 protein was not altered in any of the treatment groups except in captopril treated rats were ACE1 expression was increased. Renal ACE2 protein expression was only increased in T4-losartan-treated rats and not affected by any of the other treatments.

CONCLUSION

We conclude that losartan was more protective than captopril against thyroxine-induced renal changes while Ang 1-7 offered no protection.

Advancement in Beneficial Effects of AVE 0991: A Brief Review

AVE 0991, a non-peptide analogue of Angiotensin-(1-7) [Ang-(1-7)], is orally active and physiologically well tolerated. Several studies have demonstrated that AVE 0991 improves glucose and lipid metabolism, and contains anti-inflammatory, anti-apoptotic, anti-fibrosis, and anti-oxidant effects. Numerous preclinical studies have also reported that AVE 0991 appears to have beneficial effects on a variety of systemic diseases, including cardiovascular, liver, kidney, cancer, diabetes, and nervous system diseases. This study searched multiple literature databases, including PubMed, Web of Science, EMBASE, Google Scholar, Cochrane Library, and the ClinicalTrials.gov website from the establishment to October 2022, using AVE 0991 as a keyword. This literature search revealed that AVE 0991 could play different roles via various signaling pathways. However, the potential mechanisms of these effects need further elucidation. This review summarizes the benefits of AVE 0991 in several medical problems, including the COVID-19 pandemic. The paper also describes the underlying mechanisms of AVE 0991, giving in-depth insights and perspectives on the pharmaceutical value of AVE 0991 in drug discovery and development.

Evaluating the potential of tauroursodeoxycholic acid as add-on therapy in amelioration of streptozotocin-induced diabetic kidney disease

The bile acid tauroursodeoxycholic acid (TUDCA) is of natural origin and is used in traditional Chinese medicine for centuries. Earlier its use was limited to biliary disorders but owing to its pleiotropic effects dietary TUDCA supplementation is under clinical trials for diseases including type 1 and 2 diabetic complications. The current study aims to evaluate the potential and underlying molecular mechanism of the TUDCA as a monotherapy and as an add-on therapy to telmisartan, an angiotensin II type 1 receptor (AT1R) blocker against diabetic kidney disease (DKD). We employed both in-vitro and in-vivo approaches where NRK-52E cells were incubated with high glucose, and DKD was induced in Wistar rats using streptozotocin (55 mg/kg, i.p.). After 4 weeks, animals were administered with TUDCA (250 mg/kg, i.p.), telmisartan (10 mg/kg, p.o.), and their combination for 4 weeks. Plasma was collected for the biochemical estimation and kidneys were used for immunoblotting, PCR, and histopathological analysis. Similarly, for in-vitro experiments, cells were exposed to 1000 μM of TUDCA and 10 μM of telmisartan, and their combination, followed by cell lysate collection and immunoblotting analysis. We observed that the addition of TUDCA to conventional telmisartan treatment was more effective in restoring the renal function decline and suppressing the apoptotic and fibrotic signaling as compared to monotherapies of AT1R blocker and ER stress inhibitor. The results implicate the utility of traditionally used TUDCA as a potential renoprotective compound. Since, both TUDCA and telmisartan are approved for clinical usage, thus concomitant administration of them could be a novel therapeutic strategy against DKD.

Alamandine: A promising treatment for fibrosis

Angiotensin (Ang) II, the main active member of the renin angiotensin system (RAS), is essential for the maintenance of cardiovascular homeostasis. However, hyperactivation of the RAS causes fibrotic diseases. Ang II has pro-inflammatory actions, and moreover activates interstitial fibroblasts and/or dysregulates extracellular matrix degradation. The discovery of new RAS pathways has revealed the complexity of this system. Among the RAS peptides, alamandine (ALA, Ala¹ Ang 1-7) has been identified in humans, rats, and mice, with protective actions in different pathological conditions. ALA has similar effects to its well-known congener, Ang-(1-7), as a vasodilator, anti-inflammatory, and antifibrotic. Its protective role against cardiovascular diseases is well-reviewed in the literature. However, the protective actions of ALA in fibrotic conditions have been little explored. Therefore, in this article, we review the ability of ALA to modulate the inflammatory process and collagen deposition, to serve as an antioxidant, and to mediate protection against functional disorders. In this scenario, we also explore ALA as a promising therapy for pulmonary fibrosis after COVID-19 infection.

Angiotensin-(1-7), a protective peptide against vascular aging

Vascular aging is a complex and multifaceted process that provokes profound molecular, structural, and functional changes in the vasculature. Eventually, these profound aging alterations make arteries more prone to vascular disease, including hypertension, atherosclerosis and other arterial complications that impact the organism beyond the cardiovascular system and accelerate frailty. For these reasons, preventing or delaying the hallmarks of vascular aging is nowadays a major health goal, especially in our aged societies. In this context, angiotensin(Ang)-(1-7), a major player of the protective branch of the renin-angiotensin system, has gained relevance over recent years as growing knowledge on its anti-aging properties is being unveiled. Here, we briefly review the main actions of Ang-(1-7) against vascular aging. These include protection against vascular cell senescence, anti-inflammatory and antioxidant effects together with the induction of cytoprotective systems. Ang-(1-7) further ameliorates endothelial dysfunction, a hallmark of vascular aging and disease, attenuates fibrosis and calcification and promotes protective angiogenesis and repair. Although further research is needed to better understand the anti-aging properties of Ang-(1-7) on the vasculature, this heptapeptide arises as a promising pharmacological tool for preventing vascular aging and frailty.

Angiotensin 1-7 mitigates rhabdomyolysis induced renal injury in rats via modulation of TLR-4/NF-kB/iNOS and Nrf-2/heme‑oxygenase-1 signaling pathways

AIMS

Rhabdomyolysis (RM) is a critical condition with a high mortality rate, but effective management is still deficient. Till date, there are no studies that have addressed the effect of angiotensin 1-7 in this condition, hence, the rationale of this study was to evaluate the potential protective effect of Angiotensin 1-7 (Ang1-7), on rhabdomyolysis (RM) induced kidney injury in rats and detecting the underlying mechanistic insights.

MAIN METHODS

Forty adult male albino rats were divided into groups; the control group, RM group, RM+Ang1-7 group, and RM+Ang1-7+ A779 group. Sera and urine samples were collected for analysis of renal and muscle injury markers. Kidney tissues were taken for estimation of oxidative, inflammatory, and apoptotic markers as well as angiotensin-II (Ang II) and Ang1-7. Renal histology and expression of inducible nitric oxide synthase-1 (iNOS), real-time PCR for angiotensin-converting enzyme-2 (ACE-2), nuclear erythroid factor-2 (Nrf-2), Toll like receptor 4 (TLR-4) and NF-kB in kidney tissues were also measured.

KEY FINDINGS

Induction of RM caused renal oxidative stress injury, inflammation, apoptosis and marked deterioration in kidney functions as well as reduction of Ang1-7 and raised Angiotensin-II level in kidney tissues. Administration of Ang1-7 to the RM group reversed all the affected parameters which were blocked by A779 administration (Mas receptor blocker).

SIGNIFICANCE

We concluded that Ang1-7 could be a potential therapeutic agent that could mitigate RM-induced renal injury. The underlying mechanisms may involve Stimulation of the ACE-2/Ang1-7/MasR axis and modulation of TLR-4/NF-kB/iNOS and Nrf-2/heme‑oxygenase -1 pathways.

Angiotensin-(1-7) improves diabetes mellitus-induced erectile dysfunction in rats by regulating nitric oxide synthase levels

This study explores the role of inducible nitric oxide synthase (iNOS) in the pathogenesis of diabetes mellitus-induced erectile dysfunction (DMED) and the effect of angiotensin 1-7 (Ang- [1-7]) on NOS levels. A type 2 diabetes mellitus (DM) rat model was established. Erectile function was assessed by measuring intracavernous pressure and mean arterial pressure after electrical stimulation. The expression of iNOS, endothelial NOS (eNOS), eNOS phosphorylated at Ser 1177 (p-eNOS [Ser 1177]), and AKT/p-AKT in corpus cavernosum smooth muscle cells (CCSMCs) was measured by Western blotting and immunofluorescence. The plasma levels of NO, SOD, malondialdehyde, and peroxynitrite were calculated. Intracellular calcium content was determined by flow cytometry. DMED rats exhibited decreased erectile function and severe oxidative stress. Ang-(1-7) treatment improved erectile response and suppressed oxidative stress by upregulating p-eNOS/eNOS and downregulating iNOS levels. Silencing iNOS in CCSMCs decreased oxidative stress and intracellular calcium levels induced by high glucose. In turn, iNOS overexpression increased oxidative stress and intracellular calcium level. Treatment with the MAS receptor antagonist A779 and the Akt antagonist LY294002 reversed the effects of Ang-(1-7) on iNOS. Ang-(1-7) improved DMED through the MAS/AKT signaling pathway.

Fibrosis, the Bad Actor in Cardiorenal Syndromes: Mechanisms Involved

Cardiorenal syndrome is a term that defines the complex bidirectional nature of the interaction between cardiac and renal disease. It is well established that patients with kidney disease have higher incidence of cardiovascular comorbidities and that renal dysfunction is a significant threat to the prognosis of patients with cardiac disease. Fibrosis is a common characteristic of organ injury progression that has been proposed not only as a marker but also as an important driver of the pathophysiology of cardiorenal syndromes. Due to the relevance of fibrosis, its study might give insight into the mechanisms and targets that could potentially be modulated to prevent fibrosis development. The aim of this review was to summarize some of the pathophysiological pathways involved in the fibrotic damage seen in cardiorenal syndromes, such as inflammation, oxidative stress and endoplasmic reticulum stress, which are known to be triggers and mediators of fibrosis.

Countermeasure and therapeutic: A(1-7) to treat acute respiratory distress syndrome due to COVID-19 infection

In the wake of the COVID-19 pandemic it has become clear that there is a need for therapies that are capable of reducing damage caused to patients from infections. Infections that induce Acute Respiratory Distress Syndrome (ARDS) are especially devastating because lung damage is so critical and difficult to manage. Angiotensin (1–7) [A(1–7)] has already been shown to protect pulmonary health and architecture in various models of disease. There is also evidence that A(1–7) can modulate immune function and protect various organs (lung, kidney, and heart) from oxidative damage and inflammation. Here we focus on making a case for the development of novel therapies that target the protective arm of the Renin Angiotensin System (RAS).

Angiotensin-[1-7] attenuates kidney injury in experimental Alport syndrome

Angiotensin-[1–7] (Ang-[1–7]) antagonize the actions of the renin-angiotensin-system via the Mas receptor and thereby exert renoprotective effects. Murine recombinant angiotensin-converting enzyme (ACE)2 was reported to show renoprotective effects in an experimental Alport syndrome model; however, the protective effect of direct administration of Ang-[1–7] is unknown. Here, we used Col4a3^−/− mice as a model of Alport syndrome, which were treated with saline or Ang- [1–7]; saline-treated wild-type mice were used as a control group. The mice were continuously infused with saline or Ang-[1–7] (25 μg/kg/h) using osmotic mini-pumps. Col4a3^−/− mice showed increased α-smooth muscle actin (SMA), collagen, and fibronectin expression levels, which were attenuated by Ang-[1–7] treatment. Moreover, Ang-[1–7] alleviated activation of transforming growth factor-β/Smad signaling, and attenuated the protein expression of ED-1 and heme oxygenase-1, indicating reduction of renal inflammation. Ang-[1–7] treatment further reduced the expression levels of inflammatory cytokines and adhesion molecules and attenuated apoptosis in human kidney cells. Finally, Ang-[1–7] downregulated TNF-α converting enzyme and upregulated ACE2 expression. Thus, treatment with Ang-[1–7] altered the ACE2-Ang-[1–7]-Mas receptor axis in the kidneys of Col4a3^−/− mice to attenuate the nephropathy progression of Alport syndrome.