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      Could a specific ACE2 activator drug improve the clinical outcome of SARS-CoV-2? A potential pharmacological insight

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      a , b , b

      Expert Review of Clinical Pharmacology

      Taylor & Francis

      SARS-CoV-2, coronavirus, diminazene, ACE2, lung injury, pharmacology

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          Abstract

          1. Introduction It has been known since the first identified SARS epidemic that the receptor critical for SARS-CoV entry into host cells is the angiotensin-converting enzyme 2 (ACE2), an important actor on renin-angiotensin system (RAS) [1,2]. Similarly, with the novel coronavirus (SARS-CoV-2), the S1 domain of the spike protein (SARS-2-S) attaches the virus to its cellular receptor ACE2 on the host cells. The subsequent step is the ACE2 downregulation by primary enzyme TACE and TMPRSS2, which culminate on the receptor cleavage [3,4]. The partial lack of ACE2 expression has protagonist post on the severe lung injury by SARS-CoV [5,6]. 2. The role of the ACE2 in the lung and the SARS infection damage ACE2 expression occurs in alveoli-type 2 pneumocytes and macrophages present into the pulmonary parenchyma [7]. Indeed, ACE2 displays advantageous function in several tissues including the lungs. Abundant expression in pulmonary tissue can be attributed to its defensive feature against several diseases. Recent studies have demonstrated that ACE2 protects murine lungs from acute lung injury as well as SARS-spike protein-mediated lung injury, suggesting an important role of ACE2 in SARS infections and protection from ARDS [8]. Based on these SARS effects, it could be thought initially that the RAS blockers might increase the risk of developing a notorious and sometimes fatal severe acute respiratory syndrome coronavirus infection since ACE2 can be triggered by clinical RAS inhibition. However, Meng and coworkers, in a brilliant discussion, showed the first clinical evidence that RAS inhibitors improve the clinical outcomes of Covid-19 patients with hypertension [9]. In another study, it was proposed that there are no data supporting that ACE inhibitors (ACEi) or angiotensin II type 1 receptor blockers facilitate coronavirus entry by increasing ACE2 expression and the authors suggest that treatment with RAS blockers should not be discontinued because of concerns with coronavirus infection based on the currently available evidence [10]. When it comes to assessing hyperinflammation in Covid-19, a clinical study compared IL-6, an inflammatory marker found in SARS-CoV-2 positive patients on ACEi versus non-ACEi therapy, revealing that the cytokine levels were reduced in the ACEi group [9]. More recently, Khashkhusha and colleagues reported an interesting editorial emphasizing the fact that we do not yet know exactly the clinical benefit of using ACEi. Indeed, they suggested that large studies are needed to delineate the role of ACEi in treating Covid-19, ideally both in patients naïve to ACEi and chronic users of ACEi [11]. Wang and Cheng reported that SARS-CoV and MERS-CoV upregulate the expression of ACE2 in lung tissue, a process that could accelerate their replication and spread. Indeed, based on a causative course, this is expected [12]. Nevertheless, this event of increased ACE2 expression by PCR techniques could reveal compensatory effect due to the virus entry mechanism. Thereby, how could be the pattern of ACE2 expression not only its related mRNA as Wang and Cheng showed? Kuba and colleagues published an interesting experimental model injecting SARS-spike protein to mimic the inflammatory response on lung tissue. Indeed, this event may explain that PCR was not the best perspective to evaluate the enzyme expression since they detected by blot analysis the ACE2 downregulation associated to increased Ang II, a proinflammatory peptide when binds to AT1 receptors [13]. Recently, our research group raised a putative connection between ACE2 downregulation and harmful role of its imbalance on Covid-19. The medical hypothesis speculates that ACE2 when downregulated promotes bradykinin (BK) and des-Arg9-BK excess culminating in cytokine storm owing to BK-receptors type 1 binding [14] It is noteworthy that ACE2 expression is not restricted to the lung, but also extra pulmonary spread of SARS-CoV-2 in ACE2 positive tissues was observed such as heart, liver, kidney, and GI tract [15,16]. We thought that it is timely to explain the connection between the ACE2 in late stages of SARS-CoV-2 and the association with rationale use of ACE2 activators as a potential therapy. Yang and colleagues showed in an experimental murine model of SARS-CoV infection that overexpression of human ACE2 enhanced disease severity, demonstrating that viral entry into cells is a critical step [17]. Nevertheless, up to our knowledge, no study has shown if reestablishment of ACE2 on pneumocytes and lung parenchyma could led to an improvement of pulmonary function and attenuation of inflammatory response in SARS-CoV-2 during late phase, which includes specially cytokine storm and failure in gas exchange, as well as extra lung damage such as heart tissue and gut repercussions. So, based in all these findings, we believe that the ACE2 specific activators could achieve useful properties in severe acute respiratory syndrome induced by SARS-CoV-2 infection. 3. Therapy for Covid-19 is still required As an acute viral disease, Covid-19 has some phases already observed and suggestively proposed by epidemiologists. Chakraborty and colleagues (2020) published a very organized compilation which brings these phases of coronavirus outbreak with SARS-CoV-2 in (i) incubation period (up to 5 days), (ii) symptoms appear (6–7 days); (iii) painful breathing (8 day); (iv) respiratory distress syndrome – acute phase (9 days), and (v) severe case – patient admitted to ICU (more than 10 days). In early stages, before acute phase, the appropriate recommendation in the scope of medical virology is the use of antivirals to mitigate viral replication. In Covid-19, there is not a specific antiviral although a plenty of clinical studies are ongoing with off-label medications such as chloroquine, hydroxychloroquine, lopinavir, and remdesivir [18,19]. However, in late phases, patients with Covid-19 have been minor benefits with antiviral therapies. Recently, preliminary study results suggested dexamethasone, a commonly used steroid, to reduce risk of death in sickest Covid-19 patients [20]. Clinical pharmacology is yet seeking effective options for treating Covid-19 due to the high nonresponsive patients to suggested drugs up to this date. In terms of massive control of a viral pandemic, the most expected is the intervention of an effective vaccine to achieve herd immunity. There are many speculations and advanced studies regarding to vaccines based on known epitopes, notably focused on spike glycoprotein of SARS-CoV-2, which recognizes the gateway ACE2 and triggers an immune response characterized by hyperinflammation [21]. Meanwhile, it’s noteworthy that the world is yet urging for therapeutic options in this pandemic scenario with emphasis on late stages. 4. Embarking effect of ACE2-angiotensin 1–7/Mas receptor Axis in SARS-CoV-2 Diminazene aceturate (Dize: C14H15N7 · 2C4H7NO3; Molecular Weight: 515.5 g/mol; PubChem CID: 5,284,544) is an old antiparasitic used primarily in animal clinical practice that activates ACE2. Dize is an aromatic diamidine that was first described in 1955 and has been originally developed for therapeutic approach in controlling trypanosomiasis, its IUPAC name is 2-acetamido acetic acid; 4-[2-(4-carbami midoylphenyl) iminohydrazinyl] benzene carboximidamide [22]. Nevertheless, in recent years, this drug has been extensively studied with regard to its therapeutic potential and manifold effects; this pleiotropy for pharmacology development has consequently attracted palpable interest in drug repositioning [22]. Actually, several studies have shown that Dize may influence positively other physiological conditions in different tissues ACE2+. In addition to activating ACE2, this drug stimulates the protective axis of the RAS, leading to the cleavage of Ang II. ACE2 metabolizes Ang II to Ang-(1–7) and thus counter regulates the deleterious effects of Ang II [23]. Dize seems to be a daring candidate in experimental approaches of SARS-CoV-2 infection due to its (1) directly ACE2 activation, (2) anti-inflammatory profile, and (3) known tolerable use in humans, Berenil® is and FDA-approved drug since the last century [22,24–26]. Recently, Fang and coworkers have demonstrated the beneficial effects of Dize in pulmonary disorders in animal models by regulating NF-κB and Nrf2 gene expression routes which encode proinflammatory cytokines that compromise lung function [27]. Could the diminution in ACE2 levels explain partially the reasons for this damage? In the same study, the authors showed lower expression of ACE2/Ang-(1-7) in lung tissue and bronchoalveolar lavage fluid of mice with hyperoxia, while Dize restored ACE2 and this favorable phenomenon was aggravated by MLN-4476, an ACE2 inhibitor. Dize also diminished vascular permeability and parameters of pulmonary edema followed by controlled oxidative stress on induced-hyperoxia lung damage in mice. Another study developed by Imai and colleagues showed pivotal protective role of ACE2 on mice with severe acute lung injury induced by acid aspiration or sepsis [28]. However, no studies have explored the off-label effects of Dize on epithelial and connective tissue and the role of the ACE2/Ang-(1-7)/Mas receptor pathway in healing of acute lung injury induced by SARS-CoV and SARS-CoV-2. It is worth mentioning that although lung injury followed by cytokine storm is the major complication in Covid-19 on pnemocytes into the alveolar epithelial cells, but there is remote damage in other tissues ACE2+ such as heart, liver, and sometimes underestimated on intestine causing diarrhea [15,29–34]. Dize also has shown that reestablishment of ACE2 in these tissues suggests advantageous guidance of thinking about its multi target fashion drug for SARS-CoV-2 far-off injuries [35–37]. 5. Conclusion We hypothesize as novel therapeutic strategy for late stage mainly in pulmonary complications provoked by SARS-CoV-2 infection, but also remote damages, based on specific ACE2 activation, with diminazene aceturate, and that may important specially for nonresponsive patients to management protocols purposed by now (see Figure 1). If ACE2 levels are restored in tissues that SARS-CoV-2 reduced its expression, and this is the resumption of homeostasis, we can be close to the control of a pandemic through this therapeutic proposal. Figure 1. Hypothetical scheme. (a) SARS-CoV-2 infection is characterized by the collapse of the alveoli orchestrated by the decrease in the surfactant layer, followed by the release of inflammatory mediators culminating in the cytokine storm and impaired by the downregulation in ACE2; while (b) diminazene aceturate, an ACE2 activator, could improve late clinical outcome due to its anti-inflammatory and tissue protectant profile by reduction of proinflammatory cytokines, by augmenting surfactant proteins ACE2 dependent followed by ACE2 activation and speculated upregulation of ACE2 expression in late stages of Covid-19.

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          Most cited references 21

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          SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a Clinically Proven Protease Inhibitor

          Summary The recent emergence of the novel, pathogenic SARS-coronavirus 2 (SARS-CoV-2) in China and its rapid national and international spread pose a global health emergency. Cell entry of coronaviruses depends on binding of the viral spike (S) proteins to cellular receptors and on S protein priming by host cell proteases. Unravelling which cellular factors are used by SARS-CoV-2 for entry might provide insights into viral transmission and reveal therapeutic targets. Here, we demonstrate that SARS-CoV-2 uses the SARS-CoV receptor ACE2 for entry and the serine protease TMPRSS2 for S protein priming. A TMPRSS2 inhibitor approved for clinical use blocked entry and might constitute a treatment option. Finally, we show that the sera from convalescent SARS patients cross-neutralized SARS-2-S-driven entry. Our results reveal important commonalities between SARS-CoV-2 and SARS-CoV infection and identify a potential target for antiviral intervention.
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            COVID-19: consider cytokine storm syndromes and immunosuppression

            As of March 12, 2020, coronavirus disease 2019 (COVID-19) has been confirmed in 125 048 people worldwide, carrying a mortality of approximately 3·7%, 1 compared with a mortality rate of less than 1% from influenza. There is an urgent need for effective treatment. Current focus has been on the development of novel therapeutics, including antivirals and vaccines. Accumulating evidence suggests that a subgroup of patients with severe COVID-19 might have a cytokine storm syndrome. We recommend identification and treatment of hyperinflammation using existing, approved therapies with proven safety profiles to address the immediate need to reduce the rising mortality. Current management of COVID-19 is supportive, and respiratory failure from acute respiratory distress syndrome (ARDS) is the leading cause of mortality. 2 Secondary haemophagocytic lymphohistiocytosis (sHLH) is an under-recognised, hyperinflammatory syndrome characterised by a fulminant and fatal hypercytokinaemia with multiorgan failure. In adults, sHLH is most commonly triggered by viral infections 3 and occurs in 3·7–4·3% of sepsis cases. 4 Cardinal features of sHLH include unremitting fever, cytopenias, and hyperferritinaemia; pulmonary involvement (including ARDS) occurs in approximately 50% of patients. 5 A cytokine profile resembling sHLH is associated with COVID-19 disease severity, characterised by increased interleukin (IL)-2, IL-7, granulocyte-colony stimulating factor, interferon-γ inducible protein 10, monocyte chemoattractant protein 1, macrophage inflammatory protein 1-α, and tumour necrosis factor-α. 6 Predictors of fatality from a recent retrospective, multicentre study of 150 confirmed COVID-19 cases in Wuhan, China, included elevated ferritin (mean 1297·6 ng/ml in non-survivors vs 614·0 ng/ml in survivors; p 39·4°C 49 Organomegaly None 0 Hepatomegaly or splenomegaly 23 Hepatomegaly and splenomegaly 38 Number of cytopenias * One lineage 0 Two lineages 24 Three lineages 34 Triglycerides (mmol/L) 4·0 mmol/L 64 Fibrinogen (g/L) >2·5 g/L 0 ≤2·5 g/L 30 Ferritin ng/ml 6000 ng/ml 50 Serum aspartate aminotransferase <30 IU/L 0 ≥30 IU/L 19 Haemophagocytosis on bone marrow aspirate No 0 Yes 35 Known immunosuppression † No 0 Yes 18 The Hscore 11 generates a probability for the presence of secondary HLH. HScores greater than 169 are 93% sensitive and 86% specific for HLH. Note that bone marrow haemophagocytosis is not mandatory for a diagnosis of HLH. HScores can be calculated using an online HScore calculator. 11 HLH=haemophagocytic lymphohistiocytosis. * Defined as either haemoglobin concentration of 9·2 g/dL or less (≤5·71 mmol/L), a white blood cell count of 5000 white blood cells per mm3 or less, or platelet count of 110 000 platelets per mm3 or less, or all of these criteria combined. † HIV positive or receiving longterm immunosuppressive therapy (ie, glucocorticoids, cyclosporine, azathioprine).
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              Liver injury during highly pathogenic human coronavirus infections

               Ling Xu,  Jia Liu,  Mengji Lu (2020)
              Abstract The severe acute respiratory syndrome coronavirus 2 (SARS‐Cov‐2), the pathogen of 2019 novel coronavirus disease (COVID‐19), has posed a serious threat to global public health. The WHO has declared the outbreak of SARS‐CoV‐2 infection an international public health emergency. Lung lesions have been considered as the major damage caused by SARS‐CoV‐2 infection. However, liver injury has also been reported to occur during the course of the disease in severe cases. Similarly, previous studies have shown that liver damage was common in the patients infected by the other two highly pathogenic coronavirus – severe acute respiratory syndrome coronavirus (SARS‐CoV) and the Middle East respiratory syndrome coronavirus (MERS‐CoV), and associated with the severity of diseases. In this review, the characteristics and mechanism of liver injury caused by SARS‐CoV, MERS‐CoV as well as SARS‐CoV‐2 infection were summarized, which may provide help for further studies on the liver injury of COVID‐19.
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                Author and article information

                Journal
                Expert Rev Clin Pharmacol
                Expert Rev Clin Pharmacol
                Expert Review of Clinical Pharmacology
                Taylor & Francis
                1751-2433
                1751-2441
                25 July 2020
                2020
                : 1-5
                Affiliations
                [a ]Department of Medicine, Federal University of Parnaíba Delta; , Parnaíba, Brazil
                [b ]Biotechnology and Biodiversity Center Research (BIOTEC), Federal University of Parnaíba Delta; , Parnaíba, Brazil
                Author notes
                CONTACT Jand V. R. Medeiros jandvenes@ 123456ufpi.edu.br Biotechnology and Biodiversity Center Research (BIOTEC), Federal University of Parnaíba Delta; , Parnaíba, Piauí, Brazil
                Article
                1798760
                10.1080/17512433.2020.1798760
                7441754
                32686527
                © 2020 Informa UK Limited, trading as Taylor & Francis Group

                This article is made available via the PMC Open Access Subset for unrestricted re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the COVID-19 pandemic or until permissions are revoked in writing. Upon expiration of these permissions, PMC is granted a perpetual license to make this article available via PMC and Europe PMC, consistent with existing copyright protections.

                Page count
                Figures: 1, References: 37, Pages: 5
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                Editorial

                sars-cov-2, coronavirus, diminazene, ace2, lung injury, pharmacology

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