Anti-inflammatory effects of the activation of the angiotensin-(1-7) receptor, MAS, in experimental models of arthritis

Resolution pharmacology and the treatment of infectious diseases

Inflammation is elicited by the host in response to microbes, and is believed to be essential for protection against infection. However, we have previously hypothesized that excessive or misplaced inflammation may be a major contributor to tissue dysfunction and death associated with viral and bacterial infections. The resolutive phase of inflammation is a necessary condition to achieve homeostasis after acute inflammation. It is possible that targeting inflammation resolution may be beneficial for the host during infection. In this review, we summarize the evidence demonstrating the expression, roles and effects of the best described pro-resolving molecules in the context of bacterial and viral infections. Pro-resolving molecules play a pivotal role in modulating a spectrum of pathways associated with tissue inflammation and damage during both viral and bacterial infections. These molecules offer a blend of anti-inflammatory, pro-resolving and sometimes anti-infective benefits, all the while circumventing the undesired and immune-suppressive unwanted effects associated with glucocorticoids. Whether these beneficial effects will translate into benefits to patients clearly deserve further investigation.

Diverse biological functions of the renin-angiotensin system

The renin-angiotensin system (RAS) has been widely known as a circulating endocrine system involved in the control of blood pressure. However, components of RAS have been found to be localized in rather unexpected sites in the body including the kidneys, brain, bone marrow, immune cells, and reproductive system. These discoveries have led to steady, growing evidence of the existence of independent tissue RAS specific to several parts of the body. It is important to understand how RAS regulates these systems for a variety of reasons: It gives a better overall picture of human physiology, helps to understand and mitigate the unintended consequences of RAS-inhibiting or activating drugs, and sets the stage for potential new therapies for a variety of ailments. This review fulfills the need for an updated overview of knowledge about local tissue RAS in several bodily systems, including their components, functions, and medical implications.

Angiotensin-(1-7) plays an important role in regulating spermatogenesis in Trachemys scripta elegans under salinity stress

Elevation in water salinity can threaten the spermatogenesis and fertility of freshwater animals. The role of the renin-angiotensin system (RAS) in regulating spermatogenesis has attracted considerable attention. Our previous study found that red-eared sliders (Trachemys scripta elegans), could survive in 10 PSU water for over 1 year. To understand the chronic impact of salinity on testicular spermatogenesis and underlying mechanisms, male T. s. elegans were subjected to treatment with water of 5 PSU and 10 PSU for a year, and spermatogenesis and regulation of the RAS signal pathway was assessed. Results showed induced inflammation in the testes of T. s. elegans in the 10 PSU group, as evidenced by a decrease in the number of testicular germ cells from 1586 to 943. Compared with the control group, the levels of proinflammatory genes, including TNF-α, IL-12A and IL-6 were elevated 3.1, 0.3, and 1.4 times, respectively, in animals exposed to 10 PSU water. Testicular antiapoptotic processes of T. s. elegans might involve the vasoactive peptide angiotensin-(1-7) in the RAS, as its level was significantly increased from 220.2 ng ml-1 in controls to 419.2 ng ml-1 in the 10 PSU group. As expected, specific inhibitor (A-779) for the Ang-(1-7) acceptor effectively prevented the salinity-induced upregulation of genes encoding anti-inflammatory and antiapoptotic factors (TGF-β1, Bcl-6) in the testis of the 10 PSU animals, whereas it promoted the upregulation of proinflammatory and proapoptotic factors (TNF-α, IL-12A, IL-6, Bax and caspase-3). Our data indicated that Ang-(1-7) attenuates the effect of salinity on inflammation and apoptosis of the testis in T. s. elegans. A new perspective to prevent salinity-induced testis dysfunction is provided.

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.

The alternative renin-angiotensin system in critically ill patients: pathophysiology and therapeutic implications

The renin-angiotensin system (RAS) plays a crucial role in regulating blood pressure and the cardio-renal system. The classical RAS, mainly mediated by angiotensin I, angiotensin-converting enzyme, and angiotensin II, has been reported to be altered in critically ill patients, such as those in vasodilatory shock. However, recent research has highlighted the role of some components of the counterregulatory axis of the classical RAS, termed the alternative RAS, such as angiotensin-converting Enzyme 2 (ACE2) and angiotensin-(1-7), or peptidases which can modulate the RAS like dipeptidyl-peptidase 3, in many critical situations. In cases of shock, dipeptidyl-peptidase 3, an enzyme involved in the degradation of angiotensin and opioid peptides, has been associated with acute kidney injury and mortality and preclinical studies have tested its neutralization. Angiotensin-(1-7) has been shown to prevent septic shock development and improve outcomes in experimental models of sepsis. In the context of experimental acute lung injury, ACE2 activity has demonstrated a protective role, and its inactivation has been associated with worsened lung function, leading to the use of active recombinant human ACE2, in preclinical and human studies. Angiotensin-(1-7) has been tested in experimental models of acute lung injury and in a recent randomized controlled trial for patients with COVID-19 related hypoxemia. Overall, the alternative RAS appears to have a role in the pathogenesis of disease in critically ill patients, and modulation of the alternative RAS may improve outcomes. Here, we review the available evidence regarding the methods of analysis of the RAS, pathophysiological disturbances of this system, and discuss how therapeutic manipulation may improve outcomes in the critically ill.

The effects of Phycocyanobilin on experimental arthritis involve the reduction in nociception and synovial neutrophil infiltration, inhibition of cytokine production, and modulation of the neuronal proteome

Introduction

The antinociceptive and pharmacological activities of C-Phycocyanin (C-PC) and Phycocyanobilin (PCB) in the context of inflammatory arthritis remain unexplored so far. In the present study, we aimed to assess the protective actions of these compounds in an experimental mice model that replicates key aspects of human rheumatoid arthritis.

Methods

Antigen-induced arthritis (AIA) was established by intradermal injection of methylated bovine serum albumin in C57BL/6 mice, and one hour before the antigen challenge, either C-PC (2, 4, or 8 mg/kg) or PCB (0.1 or 1 mg/kg) were administered intraperitoneally. Proteome profiling was also conducted on glutamate-exposed SH-SY5Y neuronal cells to evaluate the PCB impact on this key signaling pathway associated with nociceptive neuronal sensitization.

Results and discussion

C-PC and PCB notably ameliorated hypernociception, synovial neutrophil infiltration, myeloperoxidase activity, and the periarticular cytokine concentration of IFN-γ, TNF-α, IL-17A, and IL-4 dose-dependently in AIA mice. In addition, 1 mg/kg PCB downregulated the gene expression for T-bet, RORγ, and IFN-γ in the popliteal lymph nodes, accompanied by a significant reduction in the pathological arthritic index of AIA mice. Noteworthy, neuronal proteome analysis revealed that PCB modulated biological processes such as pain, inflammation, and glutamatergic transmission, all of which are involved in arthritic pathology.

Conclusions

These findings demonstrate the remarkable efficacy of PCB in alleviating the nociception and inflammation in the AIA mice model and shed new light on mechanisms underlying the PCB modulation of the neuronal proteome. This research work opens a new avenue to explore the translational potential of PCB in developing a therapeutic strategy for inflammation and pain in rheumatoid arthritis.

The Renin Angiotensin System as a Therapeutic Target in Traumatic Brain Injury

Traumatic brain injury (TBI) is a major public health problem, with limited pharmacological options available beyond symptomatic relief. The renin angiotensin system (RAS) is primarily known as a systemic endocrine regulatory system, with major roles controlling blood pressure and fluid homeostasis. Drugs that target the RAS are used to treat hypertension, heart failure and kidney disorders. They have now been used chronically by millions of people and have a favorable safety profile. In addition to the systemic RAS, it is now appreciated that many different organ systems, including the brain, have their own local RAS. The major ligand of the classic RAS, Angiotensin II (Ang II) acts predominantly through the Ang II Type 1 receptor (AT1R), leading to vasoconstriction, inflammation, and heightened oxidative stress. These processes can exacerbate brain injuries. Ang II receptor blockers (ARBs) are AT1R antagonists. They have been shown in several preclinical studies to enhance recovery from TBI in rodents through improvements in molecular, cellular and behavioral correlates of injury. ARBs are now under consideration for clinical trials in TBI. Several different RAS peptides that signal through receptors distinct from the AT1R, are also potential therapeutic targets for TBI. The counter regulatory RAS pathway has actions that oppose those stimulated by AT1R signaling. This alternative pathway has many beneficial effects on cells in the central nervous system, bringing about vasodilation, and having anti-inflammatory and anti-oxidative stress actions. Stimulation of this pathway also has potential therapeutic value for the treatment of TBI. This comprehensive review will provide an overview of the various components of the RAS, with a focus on their direct relevance to TBI pathology. It will explore different therapeutic agents that modulate this system and assess their potential efficacy in treating TBI patients.

Angiotensin-(1-7) improves tail skin heat loss and increases the survival of rats with polymicrobial sepsis

Sepsis is a serious syndrome, characterized by the excessive release of inflammatory mediators and thermoregulatory changes, being fever the most common sign. However, despite the importance of Angiotensin (Ang)-(1-7) in controlling the inflammation, the role of the peptide in the febrile response and mortality in animals submitted to experimental model of sepsis is still not clear. In this way, we evaluate the effect of continuous infusion of Ang-(1-7) in inflammatory response, thermoregulation and in mortality of Wistar male rats submitted to colonic ligation puncture (CLP). Before CLP surgery, the infusion pumps (Ang-(1-7), 1.5mg/mL or saline) were inserted into the abdominal cavity and maintained for 24hours. CLP rats showed a febrile response starting from 3h after and persisted until the 24th hour of experiment. Continuous treatment with Ang-(1-7) attenuated the febrile response and reestablished the euthermia 11h after CLP, until the end of experiment, which coincided with an increased heat loss index (HLI). This effect was associated with a decrease in production of pro-inflammatory mediators in liver, white adipose tissue (WAT) and hypothalamus. Moreover, an increase in norepinephrine (NE) content in interscapular brown adipose tissue (iBAT) was observed in CLP animals, which was attenuated with treatment with Ang-(1-7), and decreased mortality in CLP animals treated with Ang-(1-7). Taken together, the present study demonstrates that continuous infusion treatment with Ang-(1-7) can promote a global anti-inflammatory effect, reestablishing the tail skin heat loss as a key thermo-effector function, resulting in an increased survival of animals submitted to experimental sepsis.

Pharmacological Treatment for Neuroinflammation in Stress-Related Disorder

Stress is an organism’s response to a biological or psychological stressor, a method of responding to threats. The autonomic nervous system and hypothalamic–pituitary–adrenal axis (HPA axis) regulate adaptation to acute stress and secrete hormones and excitatory amino acids. This process can induce excessive inflammatory reactions to the central nervous system (CNS) by HPA axis, glutamate, renin-angiotensin system (RAS) etc., under persistent stress conditions, resulting in neuroinflammation. Therefore, in order to treat stress-related neuroinflammation, the improvement effects of several mechanisms of receptor antagonist and pharmacological anti-inflammation treatment were studied. The N-methyl-D-aspartate (NMDA) receptor antagonist, peroxisome proliferator-activated receptor agonist, angiotensin-converting enzyme inhibitor etc., effectively improved neuroinflammation. The interesting fact is that not only can direct anti-inflammation treatment improve neuroinflammation, but so can stress reduction or pharmacological antidepressants. The antidepressant treatments, including selective serotonin reuptake inhibitors (SSRI), also helped improve stress-related neuroinflammation. It presents the direction of future development of stress-related neuroinflammation drugs. Therefore, in this review, the mechanism of stress-related neuroinflammation and pharmacological treatment candidates for it were reviewed. In addition, treatment candidates that have not yet been verified but indicate possibilities were also reviewed.

Anti-Inflammatory Effects of Ang-(1-7) Bone-Targeting Conjugate in an Adjuvant-Induced Arthritis Rat Model

Rheumatoid arthritis (RA) is a chronic inflammatory condition of synovial joints that causes disability and systemic complications. Ang-(1-7), one of the main peptides in the renin-angiotensin (Ang) system (RAS), imposes its protective effects through Mas receptor (MasR) signaling. It has a short half-life, limiting its feasibility as a therapeutic agent. In this study, we evaluated the anti-inflammatory effects of Ang-(1-7)’s novel and stable conjugate (Ang. Conj.) by utilizing its affinity for bone through bisphosphonate (BP) moiety in an adjuvant-induced arthritis (AIA) rat model. The rats received subcutaneous injections of vehicle, plain Ang-(1-7), or an equivalent dose of Ang. Conj. The rats’ body weights, paws, and joints’ diameters were measured thrice weekly. After 14 days, the rats were euthanized, and the blood and tissue samples were harvested for further analysis of nitric oxide (NO) and RAS components’ gene and protein expression. The administration of Ang. Conj. reduced body weight loss, joint edema, and serum NO. Moreover, the Ang. Conj. treatment significantly reduced the classical arm components at peptide, enzyme, and receptor levels while augmenting them for the protective arm. The results of this study introduce a novel class of bone-targeting natural peptides for RA caused by an inflammation-induced imbalance in the activated RAS. Our results indicate that extending the half-life of Ang-(1-7) augments the RAS protective arm and exerts enhanced therapeutic effects in the AIA model in rats.

Add-On Cyclic Angiotensin-(1-7) with Cyclophosphamide Arrests Progressive Kidney Disease in Rats with ANCA Associated Glomerulonephritis

Rapidly progressive crescentic glomerulonephritis associated with anti-neutrophil cytoplasmic antibodies (ANCA-GN) is a major cause of renal failure. Current immunosuppressive therapies are associated with severe side effects, intensifying the need for new therapeutic strategies. The activation of Mas receptor/Angiotensin-(1-7) axis exerted renoprotection in chronic kidney disease. Here, we investigated the effect of adding the lanthionine-stabilized cyclic form of angiotensin-1-7 [cAng-(1-7)] to cyclophosphamide in a rat model of ANCA-GN. At the onset of proteinuria, Wistar Kyoto rats with ANCA-GN received vehicle or a single bolus of cyclophosphamide, with or without daily cAng-(1-7). Treatment with cAng-(1-7) plus cyclophosphamide reduced proteinuria by 85% vs. vehicle, and by 60% vs. cyclophosphamide, and dramatically limited glomerular crescents to less than 10%. The addition of cAng-(1-7) to cyclophosphamide protected against glomerular inflammation and endothelial rarefaction and restored the normal distribution of parietal epithelial cells. Ultrastructural analysis revealed a preserved GBM, glomerular endothelium and podocyte structure, demonstrating that combination therapy provided an additional layer of renoprotection. This study demonstrates that adding cAng-(1-7) to a partially effective dose of cyclophosphamide arrests the progression of renal disease in rats with ANCA-GN, suggesting that cAng-(1-7) could be a novel clinical approach for sparing immunosuppressants.

Repressed Ang 1-7 in COVID-19 Is Inversely Associated with Inflammation and Coagulation

The coronavirus SARS-CoV-2 infects host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor, which belongs to an anti-inflammatory, anti-thrombotic counter-regulatory arm of the renin-angiotensin system (RAS). ACE2 dysfunction and RAS dysregulation has been explored as a driving force in acute respiratory distress syndrome (ARDS), but data from COVID-19 patients has been inconsistent and inconclusive. We sought to identify disruptions of the classical (ACE)/angiotensin (Ang) II/Ang II type-1 receptor (AT₁R) and the counter-regulatory ACE2/Ang 1-7/Mas Receptor (MasR) pathways in patients with COVID-19 and correlate these with severity of infection and markers of inflammation and coagulation. Ang II and Ang 1–7 levels in plasma were measured by enzyme-linked immunosorbent assay (ELISA) for 230 patients, 166 of whom were SARS-CoV-2+. Ang 1–7 was repressed in COVID-19 patients compared to that in SARS-CoV-2 negative outpatient controls. Since the control cohort was less sick than the SARS-CoV-2+ group, this association between decreased Ang 1–7 and COVID-19 cannot be attributed to COVID-19 specifically as opposed to critical illness more generally. Multivariable logistic regression analyses demonstrated that every 10-pg/mL increase in plasma Ang 1–7 was associated with a 3% reduction in the odds of hospitalization (adjusted odds ratio [AOR] 0.97, confidence interval [CI] 0.95 to 0.99) and a 3% reduction in odds of requiring oxygen supplementation (AOR 0.97, CI 0.95 to 0.99) and/or ventilation (AOR 0.97, CI 0.94 to 0.99). Ang 1–7 was also inversely associated with pro-inflammatory cytokines and d-dimer in this patient cohort, suggesting that reduced activity in this protective counter-regulatory arm of the RAS contributes to the hyper-immune response and diffuse coagulation activation documented in COVID-19.

IMPORTANCE Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a unique disease, COVID-19, which ranges in severity from asymptomatic to causing severe respiratory failure and death. Viral transmission throughout the world continues at a high rate despite the development and widespread use of effective vaccines. For those patients who contract COVID-19 and become severely ill, few therapeutic options have been shown to provide benefits and mortality rates are high. Additionally, the pathophysiology underlying COVID-19 disease presentation, progression, and severity is incompletely understood. The significance of our research is in confirming the role of renin-angiotensin system dysfunction in COVID-19 pathogenesis in a large cohort of patients with diverse disease severity and outcomes. Additionally, to our knowledge, this is the first study to pair angiotensin peptide levels with inflammatory and thrombotic markers. These data support the role of ongoing clinical trials examining renin-angiotensin system-targeted therapeutics for the treatment of COVID-19.

Alamandine, a new member of the renin-angiotensin system (RAS), attenuates collagen-induced arthritis in mice via inhibiting cytokine secretion in synovial fibroblasts

Alamandine is a novel component of the renin-angiotensin system (RAS) as well as an important biologically active peptide. It has predominantly been studied in cardiovascular context. However, its role in rheumatoid arthritis (RA) remains unknown. Here we illustrated its effects on inflammatory cytokines production by synovial fibroblasts from RA and pathological changes in collagen-induced arthritis (CIA) mice. Alamandine (0.1, 1 and 10 µg/ml) did not affect the survival of the synovial fibroblasts, but decreased the migration and proinflammatory cytokines expression in TNF-α (10 ng/ml) stimulated cells in vitro. Additionally, alamandine selectively decreased phosphorylated-JNK expression induced by TNF-a stimulation in RA FLS. DBA/1 J mice were induced arthritis by a primary injection with an emulsion of bovine type II collagen (CII) and complete Freund's adjuvant (day 0) and a booster injection of CII in incomplete Freund's adjuvant (day 21). Mice were then given alamandine intraperitoneally in saline (50 μg/kg/day) from days 21-42. Histology and multiplex immunobead assay showed that alamandine treatment inhibited the development of arthritis and reduced the joint damage. This effect was accompanied by the reduced inflammatory cytokines (IL-6, IL-23, IFN-γ) mRNA expression in local joints, the decreased TNF-α, IL-6, IL-17 and the increased IL-10 levels in the serum from alamandine administrated CIA mice. In conclusion, alamandine attenuates the development of arthritis by suppressing inflammatory cytokines expression in RA synovial fibroblasts via MAPK signaling pathway, suggesting a potential therapeutic role for RA.

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.

Neuroprotection in Stroke-Focus on the Renin-Angiotensin System: A Systematic Review

Stroke is the primary cause of disability in the adult population. Hypertension represents the leading risk factor being present in almost half the patients. The renin-angiotensin system is involved in the physiopathology of stroke and has an essential impact on hypertension as a risk factor. This article targeted the role of the renin-angiotensin system in stroke neuroprotection by reviewing the current literature available. The mechanism of action of the renin-angiotensin system was observed through the effects on AT1, AT2, and Mas receptors. The neuroprotective properties ascertained by angiotensin in stroke seem to be independent of the blood pressure reduction mechanism, and include neuroregeneration, angiogenesis, and increased neuronal resistance to hypoxia. The future relationship of stroke and the renin-angiotensin system is full of possibilities, as new agonist molecules emerge as potential candidates to restrict the impairment caused by stroke.

On the Origin of Neutrophil Extracellular Traps in COVID-19

Despite ongoing vaccination COVID-19 is a global healthcare problem because of the lack of an effective targeted therapy. In severe COVID-19 manifesting as acute respiratory distress syndrome, uncontrolled innate immune system activation results in cytokine deregulation, damage-associated molecular patterns release upon tissue damage and high occurrence of thrombotic events. These pathomechanisms are linked to neutrophil function and dysfunction, particularly increased formation of neutrophil extracellular traps (NETs). While the association of NETs and severity of COVID-19 has been shown and proved, the causes of NETs formation are unclear. The aim of this review is to summarize potential inducers of NETs formation in severe COVID-19 and to discuss potential treatment options targeting NETs formation of removal.

Pro-resolving therapies as potential adjunct treatment for infectious diseases: Evidence from studies with annexin A1 and angiotensin-(1-7)

Infectious diseases, once believed to be an eradicable public health threat, still represent a leading cause of death worldwide. Environmental and social changes continuously favor the emergence of new pathogens and rapid dissemination around the world. The limited availability of anti-viral therapies and increased antibiotic resistance has made the therapeutic management of infectious disease a major challenge. Inflammation is a primordial defense to protect the host against invading microorganisms. However, dysfunctional inflammatory responses contribute to disease severity and mortality during infections. In recent years, a few studies have examined the relevance of resolution of inflammation in the context of infections. Inflammation resolution is an active integrated process transduced by several pro-resolving mediators, including Annexin A1 and Angiotensin-(1-7). Here, we examine some of the cellular and molecular circuits triggered by pro-resolving molecules and that may be beneficial in the context of infectious diseases.

[Role of ACE2 in COVID-19]

In the renin-angiotensin system (RAS), angiotensin II (AngII) converted by angiotensin converting enzyme (ACE) exerts a strong physiological activity via the AT1 receptor (AT1R). Thus, the ACE-AngII-AT1R axis positively regulates RAS. On the other hand, angiotensin converting enzyme 2 (ACE2) is known to negatively regulate RAS by degrading AngII into angiotensin 1-7 (Ang1-7). In the acute respiratory distress syndrome (ARDS), which is characterized by pulmonary hyperinflammation, the AngII-AT1R axis acts to exacerbate ARDS and the ACE2-AT2R axis acts protectively. More recently, ACE2 has been shown to be a receptor for SARS-CoV, the causative virus of severe acute respiratory syndrome (SARS), and SARS-CoV2, the causative virus of the 2019 coronavirus infection (COVID-19). Therefore, inhibition of the binding between ACE2 and virus spike protein is a drug discovery target for antiviral drugs against SARS-CoV and SARS-CoV2. In addition, when SARS and COVID-19 become severe, ARDS with cytokine storm is occured. We reported that soluble ACE2 protein and microbial-derived ACE2 like enzyme suppress pulmonary hyperinflammation due to SARS and COVID-19, respectively. In addition, it has been reported that the ACE2-soluble protein has an effect of suppressing the establishment of infection by inhibiting the binding between SARS-CoV2 and the cell membrane surface ACE2. Here, we describe the role of ACE2 in the pathophysiology of SARS/COVID-19 from the perspectives of inhibiting the progression to ARDS by suppressing pulmonary inflammation and suppressing the replication of the virus by inhibiting the binding of ACE2 to the spike protein.

Angiotensin-(1-7) Analogue AVE0991 Modulates Astrocyte-Mediated Neuroinflammation via lncRNA SNHG14/miR-223-3p/NLRP3 Pathway and Offers Neuroprotection in a Transgenic Mouse Model of Alzheimer's Disease

Objective

Emerging evidence suggests that brain angiotensin-(1–7) (Ang-(1–7)) deficiency contributes to the pathogenesis of Alzheimer’s disease (AD). Meanwhile, our previous studies revealed that restoration of brain Ang-(1–7) levels provided neuroprotection by inhibition of inflammatory responses during AD progress. However, the potential molecular mechanisms by which Ang-(1–7) modulates neuroinflammation remain unclear.

Materials and Methods

APP/PS1 mice were injected intraperitoneally with AVE0991 (a nonpeptide analogue of Ang-(1–7)) once a day for 30 consecutive days. Cognitive functions, neuronal and synaptic integrity, and inflammation-related markers were assessed. Since astrocytes played a crucial role in AD-related neuroinflammation whilst long noncoding RNAs (lncRNAs) were reported to participate in modulating inflammatory responses, astrocytes of APP/PS1 mice were isolated for high-throughput lncRNA sequencing to identify the most differentially expressed lncRNA following AVE0991 treatment. Afterward, the downstream pathways of this lncRNA in the anti-inflammatory action of AVE0991 were investigated using primary astrocytes.

Results

AVE0991 rescued spatial cognitive impairments and alleviated neuronal and synaptic damage in APP/PS1 mice. The levels of Aβ_1-42 in the brain of APP/PS1 mice were not affected by AVE0991. By employing high-throughput lncRNA sequencing, our in vitro study demonstrated for the first time that AVE0991 suppressed astrocytic NLRP3 inflammasome-mediated neuroinflammation via a lncRNA SNHG14-dependent manner. SNHG14 acted as a sponge of miR-223-3p while NLRP3 represented a direct target of miR-223-3p in astrocytes. In addition, miR-223-3p participated in the AVE0991-induced suppression of astrocytic NLRP3 inflammasome.

Conclusion

Our results suggest that Ang-(1–7) analogue AVE0991 inhibits astrocyte-mediated neuroinflammation via SNHG14/miR-223-3p/NLRP3 pathway and offers neuroprotection in APP/PS1 mice. These findings reveal the underlying mechanisms by which Ang-(1–7) inhibits neuroinflammation under AD condition and uncover the potential of its nonpeptide analogue AVE0991 in AD treatment.

Angiotensin-(1-7)/MasR axis promotes migration of monocytes/macrophages with a regulatory phenotype to perform phagocytosis and efferocytosis

Nonphlogistic migration of macrophages contributes to the clearance of pathogens and apoptotic cells, a critical step for the resolution of inflammation and return to homeostasis. Angiotensin-(1-7) [Ang-(1-7)] is a heptapeptide of the renin-angiotensin system that acts through Mas receptor (MasR). Ang-(1-7) has recently emerged as a novel proresolving mediator, yet Ang-(1-7) resolution mechanisms are not fully determined. Herein, Ang-(1-7) stimulated migration of human and murine monocytes/macrophages in a MasR-, CCR2-, and MEK/ERK1/2–dependent manner. Pleural injection of Ang-(1-7) promoted nonphlogistic mononuclear cell influx alongside increased levels of CCL2, IL-10, and macrophage polarization toward a regulatory phenotype. Ang-(1-7) induction of CCL2 and mononuclear cell migration was also dependent on MasR and MEK/ERK. Of note, MasR was upregulated during the resolution phase of inflammation, and its pharmacological inhibition or genetic deficiency impaired mononuclear cell recruitment during self-resolving models of LPS pleurisy and E. coli peritonitis. Inhibition/absence of MasR was associated with reduced CCL2 levels, impaired phagocytosis of bacteria, efferocytosis, and delayed resolution of inflammation. In summary, we have uncovered a potentially novel proresolving feature of Ang-(1-7), namely the recruitment of mononuclear cells favoring efferocytosis, phagocytosis, and resolution of inflammation. Mechanistically, cell migration was dependent on MasR, CCR2, and the MEK/ERK pathway.

The role of renin angiotensin system in the pathophysiology of rheumatoid arthritis

BACKGROUND

In rheumatoid arthritis (RA) and osteoarthritis (OA), chronic inflammatory processes lead to progresive joint destruction. The renin-angiotensin system (RAS) is involved in the pathogenesis of RA and OA. The aim of this mini-review article is to summarize evidence on the role of RAS in RA and OA.

METHODS

A non-systematic search in Pubmed included terms as "rheumatoid arthritis", "renin angiotensin system", "osteopenia", "RANKL", "DKK-1", "MMP", "inflammation", "angiogenesis", "local renin-angiotensin system", "angiotensin converting enzyme", "AT2 receptor", "Ang-(1-7)", "VEGF", "angiotensine receptor blocker", "angiotensin converting enzyme inhibitors", "renin inhibitors".

RESULTS

Both RAS axes, the classical one, formed by angiotensin converting enzyme (ACE), angiotensin (Ang) II and AT1 receptor (AT1R) and the counter-regulatory one, composed by ACE2, Ang-(1-7) and the Mas receptor, modulate inflammation and tissue damage. Ang II activates pro-inflammatory mediators and oxidative stress. Conversely, Ang-(1-7) exerts anti-inflammatory actions, decreasing cytokine release, leukocyte attraction, density of vessels, tissue damage and fibrosis. Angiogenesis facilitates inflammatory cells invasion, while osteopenia causes joint dysfunction. Up-regulated osteoclastogenisis and down-regulated osteoblastogeneses were associaed with the activation of the classical RAS axis. Three different pathways, RANKL, DKK-1 and MMPs are enhanced by classical RAS activation. The treatment of RA included methotrexate and corticosteroids, which can cause side effects. Studies with angiotensin receptor blockers (ARBs), angiotensin converting enzyme inhibitors (ACEi) and renin inhibitors have been conducted in experimental and clinical RA with promising results.

CONCLUSION

The classical RAS activation is an important mechanism in RA pathogenesis and the benefit of ARB and ACEi administration should be further investigated.

Renin-angiotensin system modulators in COVID-19 patients with hypertension: friend or foe?

Background: ACE2, a component of the non-classic renin-angiotensin system (RAS), acts as a functional receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV 2) spike protein, which enables the entry of the virus into the host cells. Non-classical ACE2 is one of two types of ACE2 that has a protective effect on vascular and respiratory cells. RAS modulators like angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are among the first-line treatment for hypertensive patients. An upregulation in ACE2 levels with RAS modulators was observed in few preclinical studies, which raised concerns regarding possible increased infectivity among patients treated with RAS modulators.Method: For shortlisting the outcome effects, open-ended, English-restricted databases, published literature, and various clinical studies performed utilizing RAS modulators in COVID 19 patients were considered. Conclusion: Current evidence reveals no increased risk of COVID-19 infection among hypertensive patients on ACEIs/ARBs compared to other antihypertensive medications. Several studies have demonstrated no detrimental effects of RAS modulators on clinical severity, hospital/intensive care unit stay, ventilation and mortality.  Hence, we can conclude that neither ARBs nor ACEIs treatment will cause any side effects or undesirable interactions in COVID-19 infected hypertensive patients.

Renin-Angiotensin-Aldosterone System and Immunomodulation: A State-of-the-Art Review

The renin–angiotensin system (RAS) has long been described in the field of cardiovascular physiology as the main player in blood pressure homeostasis. However, other effects have since been described, and include proliferation, fibrosis, and inflammation. To illustrate the immunomodulatory properties of the RAS, we chose three distinct fields in which RAS may play a critical role and be the subject of specific treatments. In oncology, RAS hyperactivation has been associated with tumor migration, survival, cell proliferation, and angiogenesis; preliminary data showed promise of the benefit of RAS blockers in patients treated for certain types of cancer. In intensive care medicine, vasoplegic shock has been associated with severe macro- and microcirculatory imbalance. A relative insufficiency in angiotensin II (AngII) was associated to lethal outcomes and synthetic AngII has been suggested as a specific treatment in these cases. Finally, in solid organ transplantation, both AngI and AngII have been associated with increased rejection events, with a regional specificity in the RAS activity. These elements emphasize the complexity of the direct and indirect interactions of RAS with immunomodulatory pathways and warrant further research in the field.

ASTHMA: ROLE OF THE ANGIOTENSIN-(1-7)/MAS PATHWAY IN PATHOPHYSIOLOGY AND THERAPY

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

RAAS: A Convergent Player in Ischemic Heart Failure and Cancer

The current global prevalence of heart failure is estimated at 64.34 million cases, and it is expected to increase in the coming years, especially in countries with a medium-low sociodemographic index where the prevalence of risk factors is increasing alarmingly. Heart failure is associated with many comorbidities and among them, cancer has stood out as a contributor of death in these patients. This connection points out new challenges both in the context of the pathophysiological mechanisms involved, as well as in the quality of life of affected individuals. A hallmark of heart failure is chronic activation of the renin-angiotensin-aldosterone system, especially marked by a systemic increase in levels of angiotensin-II, a peptide with pleiotropic activities. Drugs that target the renin-angiotensin-aldosterone system have shown promising results both in the prevention of secondary cardiovascular events in myocardial infarction and heart failure, including a lower risk of certain cancers in these patients, as well as in current cancer therapies; therefore, understanding the mechanisms involved in this complex relationship will provide tools for a better diagnosis and treatment and to improve the prognosis and quality of life of people suffering from these two deadly diseases.

Characteristics of Ang-(1-7)/Mas-Mediated Amelioration of Joint Inflammation and Cardiac Complications in Mice With Collagen-Induced Arthritis

Objectives

Rheumatoid arthritis (RA) is a disabling disease with a high incidence that is regularly accompanied by cardiovascular complications. Several studies have suggested that renin–angiotensin–aldosterone system (RAAS) is closely associated with RA. The aim of this study was to investigate the mechanisms underlying Angiotensin-(1–7) [Ang-(1–7)] and its Mas receptor agonist (AVE0991) on joint inflammation and cardiac complications in a collagen-induced arthritis (CIA) model.

Methods

Collagen type II was injected into DBA/1 mice to construct an arthritis model. CIA mice were treated with Ang-(1–7) (2.0 mg/kg intraperitoneally) and AVE0991 (3.0 mg/kg intraperitoneally). The serum levels of inflammatory cytokines [tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1 β, IL-6, and C-reactive protein (CRP)] were determined by ELISA. The mitogen-activated protein kinase (MAPK) and nuclear factor-kappaB (NF-κB) signaling pathways in joint tissues and the transforming growth factor (TGF)-β/Smad pathway and levels of α-Smooth muscle action (SMA) and β-myosin heavy chain (MHC) protein expression in cardiac tissues were assessed by western blots. The levels of TGF-β/Smad pathway, α-SMA, and β-MHC RNA in cardiac tissues were analyzed by real time-PCR. The levels of receptor activator of nuclear factor kappa ligand (RANKL) and promoting matrix metalloproteinase (MMP)-3 expression in the ankle joints were detected by immunohistochemistry and real time-PCR.

Results

Ang-(1–7) and AVE0991 reduced the levels of inflammatory cytokines and inhibited the MAPKs and NF-κB signaling pathways in ankle joint tissues, reduced RANKL and MMP3 expression, and ameliorated local joint inflammation and bone destruction compared with the control group. In addition, Ang-(1–7) and AVE0991 attenuated the TGF-β/Smad signaling pathway, reduced the levels of α-SMA and β-MHC expression, and diminished inflammatory cell infiltration into the myocardial interstitium and myocardial interstitial fibrosis in the hearts of CIA mice.

Conclusions

Ang-(1–7) alleviated joint damage caused by inflammation likely through the attenuation of NF-κB and MAPK pathways and ameliorated inflammation-induced cardiac fibrosis and activation of the TGF-β/Smad pathway. Moreover, Ang-(1–7) was likely mediated through the Mas receptor. This study provides theoretical evidence for exploring novel clinical therapeutic approaches for RA and its cardiac complications.

The role of the angiotensins in the pathogenesis of inflammatory joint disease

The significant humoral effect of the renin-angiotensin-aldosterone system on the regulation of the cardiovascular system and blood pressure has long been widely known. However, the identification and interpretation of new components of renin-angiotensin-aldosterone system in recent years can significantly expand the range of its potential effects on the body. The anti-inflammatory effect of drugs that block angiotensin II and its receptors, including in rheumatic diseases, can become practically significant for General therapists by their effect on reducing the concentration of inflammatory mediators and angiogenesis processes. The organoprotective and anti-inflammatory potentials of drugs that reduce the production of at demonstrated in vitro and in vivo experiments allow us to consider them as first-line angiotropic agents in patients with rheumatoid arthritis, especially in the presence of pathology of the cardiovascular system and kidneys.

The Role of Renin-Angiotensin-Aldosterone System in the Heart and Lung: Focus on COVID-19

The renin-angiotensin-aldosterone system (RAAS) firstly considered as a cardiovascular circulating hormonal system, it is now accepted as a local tissue system that works synergistically or independently with the circulating one. Evidence states that tissue RAAS locally generates mediators with regulatory homeostatic functions, thus contributing, at some extent, to organ dysfunction or disease. Specifically, RAAS can be divided into the traditional RAAS pathway (or classic RAAS) mediated by angiotensin II (AII), and the non-classic RAAS pathway mediated by angiotensin 1–7. Both pathways operate in the heart and lung. In the heart, the classic RAAS plays a role in both hemodynamics and tissue remodeling associated with cardiomyocyte and endothelial dysfunction, leading to progressive functional impairment. Moreover, the local classic RAAS may predispose the onset of atrial fibrillation through different biological mechanisms involving inflammation, accumulation of epicardial adipose tissue, and electrical cardiac remodeling. In the lung, the classic RAAS regulates cell proliferation, immune-inflammatory response, hypoxia, and angiogenesis, contributing to lung injury and different pulmonary diseases (including COVID-19). Instead, the local non-classic RAAS counteracts the classic RAAS effects exerting a protective action on both heart and lung. Moreover, the non-classic RAAS, through the angiotensin-converting enzyme 2 (ACE2), mediates the entry of the etiological agent of COVID-19 (SARS-CoV-2) into cells. This may cause a reduction in ACE2 and an imbalance between angiotensins in favor of AII that may be responsible for the lung and heart damage. Drugs blocking the classic RAAS (angiotensin-converting enzyme inhibitors and angiotensin receptor blockers) are well known to exert a cardiovascular benefit. They are recently under evaluation for COVID-19 for their ability to block AII-induced lung injury altogether with drugs stimulating the non-classic RAAS. Herein, we discuss the available evidence on the role of RAAS in the heart and lung, summarizing all clinical data related to the use of drugs acting either by blocking the classic RAAS or stimulating the non-classic RAAS.

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.

Xanthenone, ACE2 activator, counteracted gentamicin-induced nephrotoxicity in rats: Impact on oxidative stress and ACE2/Ang-(1-7) signaling

Nephrotoxicity is a rapid deterioration of kidney function due to exposure to nephrotoxic drugs as gentamicin. Gentamicin increases the generation of reactive oxygen species (ROS) leading to inflammatory responses and nuclear factor-κB (NF-κB) activation. The renal renin-angiotensin system (RAS) is considered a crucial regulator for physiological homeostasis and disease progression through the classic ACE/Ang-II/AT1 axis and its antagonist, ACE2/Ang-(1-7)/Mas axis which exerts an important role in the kidney. The present study evaluates the protective effects of the angiotensin-converting enzyme 2 (ACE2) activator; xanthenone; against experimental nephrotoxicity induced by gentamicin. Rats were divided into 4 groups, normal control, xanthenone (2 mg/kg, s.c), gentamicin (100 mg/kg, i.p. for one week) and xanthenone + gentamicin groups. Blood urea nitrogen (BUN) and serum creatinine levels were measured. The kidney tissues were used for estimating glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), NF-κB, Angiotensin II (AngII), and Ang-(1-7). In addition, histopathological examination and Western blot analysis of ACE2 expression were done. Xanthenone significantly restored serum levels of BUN and creatinine. Xanthenone exerted significant antioxidant effect as revealed by increased GSH content and SOD activity together with reduced MDA content. It exerted anti-inflammatory effect by significant reduction in TNF-α, NF-κB and IL-6 expression compared to gentamicin group. Xanthenone increased Ang-(1-7) and ACE2 expression while significantly decreased Ang-II expression. Histopathologically, xanthenone markedly counteracted gentamicin-induced renal aberrations. Activation of ACE2/Ang-(1-7) by xanthenone produced significant antioxidant and anti-inflammatory effects that counteracted gentamicin-induced nephrotoxicity.

Downregulation of Membrane-bound Angiotensin Converting Enzyme 2 (ACE2) Receptor has a Pivotal Role in COVID-19 Immunopathology

BACKGROUND

The Coronavirus Disease 2019 (COVID-19) is becoming the major health issue in recent human history with thousands of deaths and millions of cases worldwide. Newer research and old experience with other coronaviruses highlighted a probable underlying mechanism of disturbance of the renin-angiotensin system (RAS) that is associated with the intrinsic effects of SARS-CoV-2 infection.

OBJECTIVE

In this review, we aimed to describe the intimate connections between the RAS components, the immune system and COVID-19 pathophysiology.

METHODS

This non-systematic review article summarizes recent evidence on the relationship between COVID-19 and the RAS.

RESULTS

Several studies have indicated that the downregulation of membrane-bound ACE2 may exert a key role for the impairment of immune functions and for COVID-19 patients' outcomes. The downregulation may occur by distinct mechanisms, particularly: (1) the shedding process induced by the SARS-CoV-2 fusion pathway, which reduces the amount of membrane-bound ACE2, stimulating more shedding by the high levels of Angiotensin II; (2) the endocytosis of ACE2 receptor with the virus itself and (3) by the interferon inhibition caused by SARS-CoV-2 effects on the immune system, which leads to a reduction of ACE2 receptor expression.

CONCLUSION

Recent research provides evidence of a reduction of the components of the alternative RAS axis, including ACE2 and Angiotensin-(1-7). In contrast, increased levels of Angiotensin II can activate the AT1 receptor in several organs. Consequently, increased inflammation, thrombosis and angiogenesis occur in patients infected with SARS-COV-2. Attention should be paid to the interactions of the RAS and COVID-19, mainly in the context of novel vaccines and proposed medications.

From angiotensin-converting enzyme 2 disruption to thromboinflammatory microvascular disease: A paradigm drawn from COVID-19

We concisely review clinical, autopsy, experimental and molecular data of 2019 coronavirus disease (COVID-19). Angiotensin-converting enzyme 2 disruption and thromboinflammatory microangiopathy emerge as distinctive features. Briefly, entry of the virus into microvessels can profoundly disrupt the local renin-angiotensin system, cause endothelial injury, activate the complement cascade and induce powerful thromboinflammatory reactions, involving, in particular, von Willebrand factor, that, if widespread, may lead to microvascular plugging, ischemia and, ultimately, organ failure. We believe the current COVID-19 data consolidate a widely unrecognised paradigm of potentially fatal thromboinflammatory microvascular disease.

Angiotensin-(1-7) attenuates collagen-induced arthritis via inhibiting oxidative stress in rats

The present study was designed to investigate the anti-rheumatic effects and the mechanism of angiotensin (Ang)-(1-7) in rat models with collagen-induced arthritis (CIA). The CIA model was established using male Wistar rats by intradermal injection of bovine collagen-II in complete Freund's adjuvant at the base of the tail. The levels of angiotensin converting enzyme 2 (ACE2)/Ang-(1-7)/Mas receptor (MasR) were reduced in CIA rats. The attenuation of paw swelling and arthritis scores and improvement of indexes of spleen and thymus were done by Ang-(1-7) injection in CIA rats. The increased levels of inflammatory cytokines, such as interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ in the serum and hind paw were blocked by Ang-(1-7) administration. In addition, enhanced NADPH oxidase (Nox) activity, increased levels of superoxide anions and malondialdehyde (MDA), and weakened superoxide dismutase (SOD) activity, were all reversed by treatment with Ang-(1-7). Nox1 overexpression reversed the suppressing effects of Ang-(1-7) on paw swelling and arthritis scores in CIA rats. The Ang-(1-7)-induced improvement in spleen and thymus indexes in CIA rats was abolished by Nox1 overexpression. Nox1 overexpression reversed the inhibitory effects of Ang-(1-7) by increasing IL-1β, IL-6, TNF-α, and IFN-γ levels in the serum and hind paw of CIA rats. These results demonstrated that Nox1 increased the oxidative stress in arthritis, and Ang-(1-7) improved rheumatism in arthritis via inhibiting oxidative stress.

Usage of Angiotensin-Converting Enzyme Inhibitor or Angiotensin II Receptor Blocker in Hypertension Intracerebral Hemorrhage

BACKGROUND

Inflammation plays an essential role in secondary brain injury after intracerebral hemorrhage (ICH). Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) have been suggested to suppress neuroinflammation after central nervous system (CNS) damage in animal models. However, the role of ACEIs and ARBs in ICH patients with hypertension remains unresolved in clinic. The aim of the present study is to evaluate the effect of ACEIs/ARBs on ICH patients with hypertension using a retrospective, single-center data analysis.

METHODS

ICH patients diagnosed by computerized tomographic (CT) at Southwest Hospital, Third Military Medical University were included in the present research from January 2015 to December 2019. According to the medical history for the usage of antihypertensive drugs, patients were assigned into either ACEIs/ARBs group or non-ACEIs/ARBs group. Demographics, clinical baseline, radiological documents and treatments were collected and these data were statistically analyzed between the two groups.

RESULTS

A total of 635 ICH patients with hypertension were included and allocated into 2 groups according to the usage of antihypertensive drugs: 281 in the ACEIs/ARBs group and 354 in the non-ACEIs/ARBs group. The results presented that the 3-months mortality and prevalence of ICH-associated pneumonia were lower in ACEIs/ARBs group than that in non-ACEIs/ARBs group (5.0% vs 11.9%, p=0.002; 58.4% vs 66.7%, p=0.031). While, there was no significant difference in favorable outcome (40.2% vs 33.9%, p=0.101) between the two groups. Furthermore, patients in ACEIs/ARBs group exhibited significantly less perihematomal edema volume on days 3 (23.5 ± 14.4 versus 28.7 ± 20.1 mL, p=0.045) and 7 (21.0 ± 13.7 versus 25.7 ± 17.6 mL, p=0.044), compared to that in non- ACEIs/ARBs group.

CONCLUSION

The usage of ACEIs/ARBs helps decrease mortality, perihematomal edema volume, and prevalence of ICH-associated pneumonia in ICH patients with hypertension.

Relevance of angiotensin-(1-7) and its receptor Mas in pneumonia caused by influenza virus and post-influenza pneumococcal infection

Resolution failure of exacerbated inflammation triggered by Influenza A virus (IAV) prevents return of pulmonary homeostasis and survival, especially when associated with secondary pneumococcal infection. Therapeutic strategies based on pro-resolving molecules have great potential against acute inflammatory diseases. Angiotensin-(1-7) [Ang-(1-7)] is a pro-resolving mediator that acts on its Mas receptor (MasR) to promote resolution of inflammation. We investigated the effects of Ang-(1-7) and the role of MasR in the context of primary IAV infection and secondary pneumococcal infection and evaluated pulmonary inflammation, virus titers and bacteria counts, and pulmonary damage. Therapeutic treatment with Ang-(1-7) decreased neutrophil recruitment, lung injury, viral load and morbidity after a primary IAV infection. Ang-(1-7) induced apoptosis of neutrophils and efferocytosis of these cells by alveolar macrophages, but had no direct effect on IAV replication in vitro. MasR-deficient (MasR-/-) mice were highly susceptible to IAV infection, displaying uncontrolled inflammation, increased viral load and greater lethality rate, as compared to WT animals. Ang-(1-7) was not protective in MasR-/- mice. Interestingly, Ang-(1-7) given during a sublethal dose of IAV infection greatly reduced morbidity associated with a subsequent S. pneumoniae infection, as seen by decrease in the magnitude of neutrophil influx, number of bacteria in the blood leading to a lower lethality. Altogether, these results show that Ang-(1-7) is highly protective against severe primary IAV infection and protects against secondary bacterial infection of the lung. These effects are MasR-dependent. Mediators of resolution of inflammation, such as Ang-(1-7), should be considered for the treatment of pulmonary viral infections.

Therapeutic Strategies to Protect the Central Nervous System against Shiga Toxin from Enterohemorrhagic Escherichia coli

Infection with Shiga toxin-producing Escherichia coli (STEC) may cause hemorrhagic colitis, hemolytic uremic syndrome (HUS) and encephalopathy. The mortality rate derived from HUS adds up to 5% of the cases, and up to 40% when the central nervous system (CNS) is involved. In addition to the well-known deleterious effect of Stx, the gram-negative STEC releases lipopolysaccharides (LPS) and may induce a variety of inflammatory responses when released in the gut. Common clinical signs of severe CNS injury include sensorimotor, cognitive, emotional and/or autonomic alterations. In the last few years, a number of drugs have been experimentally employed to establish the pathogenesis of, prevent or treat CNS injury by STEC. The strategies in these approaches focus on: 1) inhibition of Stx production and release by STEC, 2) inhibition of Stx bloodstream transport, 3) inhibition of Stx entry into the CNS parenchyma, 4) blockade of deleterious Stx action in neural cells, and 5) inhibition of immune system activation and CNS inflammation. Fast diagnosis of STEC infection, as well as the establishment of early CNS biomarkers of damage, may be determinants of adequate neuropharmacological treatment in time.

Angiotensin-(1-7) Expressed From Lactobacillus Bacteria Protect Diabetic Retina in Mice

Purpose

A multitude of animal studies substantiates the beneficial effects of Ang-(1–7), a peptide hormone in the protective axis of the renin angiotensin system, in diabetes and its associated complications including diabetic retinopathy (DR). However, the clinical application of Ang-(1–7) is limited due to unfavorable pharmacological properties. As emerging evidence implicates gut dysbiosis in pathogenesis of diabetes and supports beneficial effects of probiotics, we sought to develop probiotics-based expression and delivery system to enhance Ang-(1–7) and evaluate the efficacy of engineered probiotics expressing Ang-(1–7) in attenuation of DR in animal models.

Methods

Ang-(1–7) was expressed in the Lactobacillus species as a secreted fusion protein with a trans-epithelial carrier to allow uptake into circulation. To evaluate the effects of Ang-(1–7) expressed from Lactobacillus paracasei (LP), adult diabetic eNOS^−/− and Akita mice were orally gavaged with either 1 × 10⁹ CFU of LP secreting Ang-(1–7) (LP-A), LP alone or vehicle, 3 times/week, for 8 and 12 weeks, respectively.

Results

Ang-(1–7) is efficiently expressed from different Lactobacillus species and secreted into circulation in mice fed with LP-A. Oral administration of LP-A significantly reduced diabetes-induced loss of retinal vascular capillaries. LP-A treatment also prevented loss of retinal ganglion cells, and significantly decreased retinal inflammatory cytokine expression in both diabetic eNOS^−/− and Akita mice.

Conclusions

These results provide proof-of-concept for feasibility and efficacy of using engineered probiotic species as live vector for delivery of Ang-(1–7) with enhanced bioavailability.

Translational Relevance

Probiotics-based delivery of Ang-(1–7) may hold important therapeutic potential for the treatment of DR and other diabetic complications.

ACE2 in the renin-angiotensin system

In 2020 we are celebrating the 20th anniversary of the angiotensin-converting enzyme 2 (ACE2) discovery. This event was a landmark that shaped the way that we see the renin-angiotensin system (RAS) today. ACE2 is an important molecular hub that connects the RAS classical arm, formed mainly by the octapeptide angiotensin II (Ang II) and its receptor AT1, with the RAS alternative or protective arm, formed mainly by the heptapeptides Ang-(1-7) and alamandine, and their receptors, Mas and MrgD, respectively. In this work we reviewed classical and modern literature to describe how ACE2 is a critical component of the protective arm, particularly in the context of the cardiac function, coagulation homeostasis and immune system. We also review recent literature to present a critical view of the role of ACE2 and RAS in the SARS-CoV-2 pandemic.

Exploring the Evidence Implicating the Renin-Angiotensin System (RAS) in the Physiopathology of Mood Disorders

Mood disorders include Major Depressive Disorder (MDD), Bipolar Disorder (BD) and variations of both. Mood disorders has a public health significance with high comorbidity, suicidal mortality and economic burden on the health system. Research related to mood disorders has evolved over the years to relate it with systemic conditions. The Renin Angiotensin System (RAS) has been noticed to play major physiological roles beyond renal and cardiovascular systems. Recent studies have linked RAS not only with neuro-immunological processes, but also with psychiatric conditions like mood and anxiety disorders. In this comprehensive review, we integrated basic and clinical studies showing the associations between RAS and mood disorders. Animal studies on mood disorders models - either depression or mania - were focused on the reversal of behavioral and/or cognitive symptoms through the inhibition of RAS components like the Angiotensin- Converting Enzyme (ACE), Angiotensin II Type 1 receptor (AT1) or Mas receptors. ACE polymorphisms, namely insertion-deletion (I/D), were linked to mood disorders and suicidal behavior. Hypertension was associated with neurocognitive deficits in mood disorders, which reversed with RAS inhibition. Low levels of RAS components (renin activity or aldosterone) and mood symptoms improvement with ACE inhibitors or AT1 blockers were also observed in mood disorders. Overall, this review reiterates the strong and under-researched connection between RAS and mood disorders.

Synovial fluid peptidase activity as a biomarker for knee osteoarthritis clinical progression

AIMS

To analyze the potential role of synovial fluid peptidase activity as a measure of disease burden and predictive biomarker of progression in knee osteoarthritis (KOA).

METHODS

A cross-sectional study of 39 patients (women 71.8%, men 28.2%; mean age of 72.03 years (SD 1.15) with advanced KOA (Ahlbäck grade ≥ 3 and clinical indications for arthrocentesis) recruited through the (Orthopaedic Department at the Complejo Asistencial Universitario de León, Spain (CAULE)), measuring synovial fluid levels of puromycin-sensitive aminopeptidase (PSA), neutral aminopeptidase (NAP), aminopeptidase B (APB), prolyl endopeptidase (PEP), aspartate aminopeptidase (ASP), glutamyl aminopeptidase (GLU) and pyroglutamyl aminopeptidase (PGAP).

RESULTS

Synovial fluid peptidase activity varied significantly as a function of clinical signs, with differences in levels of PEP (p = 0.020), ASP (p < 0.001), and PGAP (p = 0. 003) associated with knee locking, PEP (p = 0.006), ASP (p = 0.001), GLU (p = 0.037), and PGAP (p = 0.000) with knee failure, and PEP (p = 0.006), ASP (p = 0.001), GLU (p = 0.037), and PGAP (p < 0.001) with knee effusion. Further, patients with the greatest functional impairment had significantly higher levels of APB (p = 0.005), PEP (p = 0.005), ASP (p = 0.006), GLU (p = 0.020), and PGAP (p < 0.001) activity, though not of NAP or PSA, indicating local alterations in the renin-angiotensin system. A binary logistic regression model showed that PSA was protective (p = 0.005; Exp (B) 0.949), whereas PEP (p = 0.005) and GLU were risk factors (p = 0.012).

CONCLUSION

These results suggest synovial fluid peptidase activity could play a role as a measure of disease burden and predictive biomarker of progression in KOA. Cite this article: Bone Joint Res 2020;9(11):789-797.

A hypothesis for pathobiology and treatment of COVID-19: The centrality of ACE1/ACE2 imbalance

Angiotensin Converting Enzyme2 is the cell surface binding site for the coronavirus SARS-CoV-2, which causes COVID-19. We propose that an imbalance in the action of ACE1- and ACE2-derived peptides, thereby enhancing angiotensin II (Ang II) signalling is primary driver of COVID-19 pathobiology. ACE1/ACE2 imbalance occurs due to the binding of SARS-CoV-2 to ACE2, reducing ACE2-mediated conversion of Ang II to Ang peptides that counteract pathophysiological effects of ACE1-generated ANG II. This hypothesis suggests several approaches to treat COVID-19 by restoring ACE1/ACE2 balance: (a) AT receptor antagonists; (b) ACE1 inhibitors (ACEIs); (iii) agonists of receptors activated by ACE2-derived peptides (e.g. Ang (1-7), which activates MAS1); (d) recombinant human ACE2 or ACE2 peptides as decoys for the virus. Reducing ACE1/ACE2 imbalance is predicted to blunt COVID-19-associated morbidity and mortality, especially in vulnerable patients. Importantly, approved AT antagonists and ACEIs can be rapidly repurposed to test their efficacy in treating COVID-19. LINKED ARTICLES: This article is part of a themed issue on The Pharmacology of COVID-19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc.

Impact of angiotensin II type 1 and G-protein-coupled Mas receptor expression on the pulmonary performance of patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a severe interstitial disease with a mean survival of about 2.5-5 years after diagnosis. Its pathophysiology is still a major challenge for science. It is known that angiotensin II (Ang-II) binds AT1 receptor (AT1R) and its overactivation induces fibrosis, inflammation and oxidative stress. In contrast, activation of the Mas receptor (Mas-R) by angiotensin 1-7 opposes the harmful effects induced by Ang-II. Thus, our innovative objective was to analyze, in patients' lung with IPF, the balance between AT1R and Mas-R expression and their possible association with pulmonary spirometric parameters: forced expiratory volume in the first second (FEV1%) and forced vital capacity (FVC%). One cubic centimeter of lung tissue was obtained from IPF patients (n = 6) and from patients without IPF (n = 6) who underwent bronchial carcinoma resection. Receptor expression was quantified using western blot. AT1R expression was significantly higher (34 %) in patients with IPF (P = 0.006), whereas Mas-R was significantly less expressed (54 %) in these patients' lungs (P = 0.046). There was also a positive correlation between Mas-R expression and FEV1% (r = 0.62, P = 0.03) and FVC% (r = 0.58, P = 0.05). Conversely, AT1R expression was negatively correlated with FEV1% (r = 0.80, P = 0.002) and FVC% (r = 0.74, P = 0.006). In conclusion, our results demonstrated an increased expression of AT1R and reduced expression of Mas-R in the lung of patients with IPF. The dominance of AT1R expression is associated with reduced lung function, highlighting the role of the renin-angiotensin system peptides in the pathophysiology of IPF.

Dysregulation of Angiotensin Converting Enzyme 2 Expression and Function in Comorbid Disease Conditions Possibly Contributes to Coronavirus Infectious Disease 2019 Complication Severity

ACE2 has emerged as a double agent in the COVID-19 ordeal, as it is both physiologically protective and virally conducive. The identification of ACE2 in as many as 72 tissues suggests that extrapulmonary invasion and damage is likely, which indeed has already been demonstrated by cardiovascular and gastrointestinal symptoms. On the other hand, identifying ACE2 dysregulation in patients with comorbidities may offer insight as to why COVID-19 symptoms are often more severe in these individuals. This may be attributed to a pre-existing proinflammatory state that is further propelled with the cytokine storm induced by SARS-CoV-2 infection or the loss of functional ACE2 expression as a result of viral internalization. Here, we aim to characterize the distribution and role of ACE2 in various organs to highlight the scope of damage that may arise upon SARS-CoV-2 invasion. Furthermore, by examining the disruption of ACE2 in several comorbid diseases, we offer insight into potential causes of increased severity of COVID-19 symptoms in certain individuals. SIGNIFICANCE STATEMENT: Cell surface expression of ACE2 determines the tissue susceptibility for coronavirus infectious disease 2019 infection. Comorbid disease conditions altering ACE2 expression could increase the patient's vulnerability for the disease and its complications, either directly, through modulation of viral infection, or indirectly, through alteration of inflammatory status.

Renin-Angiotensin System and Coronavirus Disease 2019: A Narrative Review

Although clinical manifestations of the 2019 novel coronavirus disease pandemic (COVID-19), caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), are mainly respiratory symptoms, patients can also develop severe cardiovascular damage. Therefore, understanding the damage caused by SARS-COV-2 to the cardiovascular system and the underlying mechanisms is fundamental. The cardiovascular damage may be related to the imbalance of the renin-angiotensin-system (RAS) as this virus binds the Angiotensin-Converting-Enzyme 2 (ACE2), expressed on the lung alveolar epithelial cells, to enter into cells. Virus internalization may cause a downregulation of ACE2 on host cell surface that could lead to a local increased level of angiotensin II (AII) and a reduced level of angiotensin 1-7 (A1-7). An imbalance between these angiotensins may be responsible for the lung and heart damage. Pharmacological strategies that interfere with the viral attachment to ACE2 (umifenovir and hydroxychloroquine/chloroquine) or that modulate the RAS (analogous of A1-7 and ACE2, losartan) are in clinical development for COVID-19. The use of RAS inhibitors has also become a matter of public concern as these drugs may increase the mRNA expression and levels of ACE2 and impact the virulence and transmission of SARS-COV-2. Data on the effect of RAS inhibitors on ACE2 mRNA expression are scarce. Scientific societies expressed their opinion on continuing the therapy with RAS inhibitors in patients with COVID-19 and underlying cardiovascular diseases. In conclusion, RAS may play a role in SARS-COV-2-induced cardiac and pulmonary damage. Further studies are needed to better understand the role of RAS in COVID-19 and to guide decision on the use of RAS inhibitors.

Designing therapeutic strategies to combat severe acute respiratory syndrome coronavirus-2 disease: COVID-19

A highly contagious coronavirus disease COVID-19 caused by a recently identified severe acute respiratory syndrome CoV-2 (SARS-CoV-2) initially detected in Wuhan, China has spread worldwide and become a major health crisis in the absence of specific vaccine or antiviral drugs. SARS-CoV-2 infection has resulted in overwhelming number of reported deaths. Unfortunately it is still spreading uncontrollably despite implementing stringent protective measures. Rapid development of effective therapeutic strategies for treatment and prevention of infection is crucially required. Although genomic characterization has assisted in unfolding various aspects of SARS-CoV-2 but development of specific antiviral drugs and vaccine against COVID-19 is still a worldwide challenge. Understanding the disease pathological course underlying the clinical manifestations of COVID-19 is imperative to identify the vital targets for drug development. SARS-CoV-2 uses angiotensin converting enzyme 2 (ACE2) receptor to enter the host cell and primarily target type II alveolar cells. COVID-19 disease progression is associated with distressed immune functions and hyper active inflammatory system leading to development of cytokine storm which is a vital factor involved in disease advancement. The current review elucidates the disease pathology and summarizes the possible therapeutic options to battle against COVID-19 on the basis of current state of understanding about SARS-CoV-2 pathogenic pathways and knowledge gained from previous SARS and MERS-CoV epidemics. Therapeutic strategies to treat and prevent infection as well as to suppress the disease progression to reduce severity and mortality rate is discussed. Drug candidates currently under consideration and undergoing clinical trials for COVID-19 treatment are highlighted.

Urgent need for evaluating agonists of angiotensin-(1-7)/Mas receptor axis for treating patients with COVID-19

ACE2 is a receptor of entry of SARS-CoV-2 into the host cells, and its upregulation has been implicated in increasing susceptibility of individuals to this infection. The clinical picture of COVID-19 suggests a role of ACE2 blockade, rather than its overexpression, in causing the pathogenesis. ACE2 blockade results in increased angiotensin II activity with simultaneous hampering of functions of angiotensin-(1-7)/MasR axis. Acute respiratory distress due to interstitial pulmonary fibrosis, cardiomyopathy and shock reported in COVID-19 patients can be explained by imbalanced angiotensin II and angiotensin-(1-7) activities. Failure of angiotensin II type 1 receptor blockers to control the severity of SARS-CoV-2 infections indicates the importance of simultaneous induction of angiotensin-(1-7)/MasR axis for correcting pathological conditions in COVID-19 through its anti-fibrotic, anti-inflammatory, vasodilatory, and cardioprotective roles. MasR agonists have also shown organ protective effects in a number of animal studies. Unfortunately, these agonists have not been tested in clinical studies. Their evaluation in seriously ill COVID-19 patients is urgently warranted to reduce mortality due to infection.

The ACE2/Ang (1-7)/MasR axis as an emerging target for antihypertensive peptides

Food protein-derived bioactive peptides, particularly antihypertensive peptides, are important constituents of functional foods or nutraceuticals. Most antihypertensive are identified as the inhibitors of angiotensin converting enzyme (ACE), a key enzyme responsible for the generation of angiotensin II (Ang II), which is a vasoconstricting peptide. Hence, ACE has long been used as a universal target to identify antihypertensive peptides. Angiotensin converting enzyme 2 (ACE2), is a homolog of ACE but uses Ang II as its key substrate to produce angiotensin (1-7), exerting vasodilatory activity via the mas receptor (MasR). Therefore, ACE2 functions in the opposite way as ACE and is an emerging novel target for cardiovascular therapy. The potential of food protein-derived bioactive peptides in targeting ACE2 has been rarely explored. While, recently we found that IRW, an egg white ovotransferrin-derived antihypertensive peptide, reduced blood pressure in spontaneously hypertensive rats via the ACE2/Ang (1-7)/MasR axis, indicating a new mechanism of food protein-derived bioactive peptides in reducing blood pressure. The objectives of this review are to summarize the functions of the ACE2/Ang (1-7)/MasR axis and to examine its potential roles in the actions of food protein-derived antihypertensive peptides. The interaction between antihypertensive peptides and the ACE2/Ang (1-7)/MasR axis will also be discussed.

A hypothesis for pathobiology and treatment of COVID-19: The centrality of ACE1/ACE2 imbalance

Angiotensin Converting Enzyme2 is the cell surface binding site for the coronavirus SARS-CoV-2, which causes COVID-19. We propose that an imbalance in the action of ACE1- and ACE2-derived peptides, thereby enhancing angiotensin II (Ang II) signalling is primary driver of COVID-19 pathobiology. ACE1/ACE2 imbalance occurs due to the binding of SARS-CoV-2 to ACE2, reducing ACE2-mediated conversion of Ang II to Ang peptides that counteract pathophysiological effects of ACE1-generated ANG II. This hypothesis suggests several approaches to treat COVID-19 by restoring ACE1/ACE2 balance: (a) AT receptor antagonists; (b) ACE1 inhibitors (ACEIs); (iii) agonists of receptors activated by ACE2-derived peptides (e.g. Ang (1-7), which activates MAS1); (d) recombinant human ACE2 or ACE2 peptides as decoys for the virus. Reducing ACE1/ACE2 imbalance is predicted to blunt COVID-19-associated morbidity and mortality, especially in vulnerable patients. Importantly, approved AT antagonists and ACEIs can be rapidly repurposed to test their efficacy in treating COVID-19. LINKED ARTICLES: This article is part of a themed issue on The Pharmacology of COVID-19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc.

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 β-cyclodextrin (HPβCD) 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 HPβCD 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)/HPβCD for 14 days reduced eosinophils, IL5, CCL11 in the lung and plasma IgE. Treatment of asthmatic mice with Ang-(1-7)/HPβCD 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.