B38-CAP is a bacteria-derived ACE2-like enzyme that suppresses hypertension and cardiac dysfunction

Study on the hypotensive effect and mechanism of hawthorn (Crataegus pinnatifida) fruits and hyperoside in spontaneously hypertensive rats

Hawthorn fruits have a sweet and sour taste, besides having beneficial therapeutic effects on hyperlipidemia, hypertension, and coronary heart disease, making them widely used in food and clinical medicine. However, their hypotensive effects and potential mechanisms of anti-hypertension still need to be elucidated. This study aims to explore the antihypertensive effect of hawthorn and its monomer hyperoside on spontaneously hypertensive rats through pharmacodynamics, serum metabolomics, and in vivo mechanism studies. After 7 weeks of intervention with hawthorn extract and hyperoside, the blood pressure was significantly reduced. Aortic vascular staining results showed that the injury was significantly improved after intervention with hawthorn extract and hyperoside. According to the serum metabolomics study, the main metabolic pathway regulating blood pressure in hawthorn extract and hyperoside groups was the primary bile acid biosynthesis pathway. Quantitative experiments confirmed that the level of bile acid in the model group was significantly different from that in the normal group, while that in the hawthorn group and the hyperoside group was close to that in the normal group. Based on the prediction of bile acid-hypertension related targets and the literature, nine genes involved in bile acid metabolism and inflammatory pathways were selected for further study. The FXR, TGR5, ET-1, NOS3, Akt1, TNF-α, Ptgs2, ACE2 and Kdr mRNA expression levels in the hawthorn extract and hyperoside groups were significantly different from those in the model groups. In summary, hawthorn extract and hyperoside have a hypotensive effect on spontaneously hypertensive rats through bile acid and inflammation related targets. Hence, hawthorn extract has the potential to become a functional food or an alternative therapy for hypertension.

Functional Foods: A Promising Strategy for Restoring Gut Microbiota Diversity Impacted by SARS-CoV-2 Variants

Natural herbs and functional foods contain bioactive molecules capable of augmenting the immune system and mediating anti-viral functions. Functional foods, such as prebiotics, probiotics, and dietary fibers, have been shown to have positive effects on gut microbiota diversity and immune function. The use of functional foods has been linked to enhanced immunity, regeneration, improved cognitive function, maintenance of gut microbiota, and significant improvement in overall health. The gut microbiota plays a critical role in maintaining overall health and immune function, and disruptions to its balance have been linked to various health problems. SARS-CoV-2 infection has been shown to affect gut microbiota diversity, and the emergence of variants poses new challenges to combat the virus. SARS-CoV-2 recognizes and infects human cells through ACE2 receptors prevalent in lung and gut epithelial cells. Humans are prone to SARS-CoV-2 infection because their respiratory and gastrointestinal tracts are rich in microbial diversity and contain high levels of ACE2 and TMPRSS2. This review article explores the potential use of functional foods in mitigating the impact of SARS-CoV-2 variants on gut microbiota diversity, and the potential use of functional foods as a strategy to combat these effects.

Nutrients, herbal bioactive derivatives and commensal microbiota as tools to lower the risk of SARS-CoV-2 infection

The SARS-CoV-2 outbreak has infected a vast population across the world, causing more than 664 million cases and 6.7 million deaths by January 2023. Vaccination has been effective in reducing the most critical aftermath of this infection, but some issues are still present regarding re-infection prevention, effectiveness against variants, vaccine hesitancy and worldwide accessibility. Moreover, although several old and new antiviral drugs have been tested, we still lack robust and specific treatment modalities. It appears of utmost importance, facing this continuously growing pandemic, to focus on alternative practices grounded on firm scientific bases. In this article, we aim to outline a rigorous scientific background and propose complementary nutritional tools useful toward containment, and ultimately control, of SARS-CoV-2 infection. In particular, we review the mechanisms of viral entry and discuss the role of polyunsaturated fatty acids derived from α-linolenic acid and other nutrients in preventing the interaction of SARS-CoV-2 with its entry gateways. In a similar way, we analyze in detail the role of herbal-derived pharmacological compounds and specific microbial strains or microbial-derived polypeptides in the prevention of SARS-CoV-2 entry. In addition, we highlight the role of probiotics, nutrients and herbal-derived compounds in stimulating the immunity response.

Angiotensin-converting enzyme 2-at the heart of the COVID-19 pandemic

ACE2 is the indispensable entry receptor for SARS-CoV and SARS-CoV-2. Because of the COVID-19 pandemic, it has become one of the most therapeutically targeted human molecules in biomedicine. ACE2 serves two fundamental physiological roles: as an enzyme, it alters peptide cascade balance; as a chaperone, it controls intestinal amino acid uptake. ACE2's tissue distribution, affected by co-morbidities and sex, explains the broad tropism of coronaviruses and the clinical manifestations of SARS and COVID-19. ACE2-based therapeutics provide a universal strategy to prevent and treat SARS-CoV-2 infections, applicable to all SARS-CoV-2 variants and other emerging zoonotic coronaviruses exploiting ACE2 as their cellular receptor.

The impact of infection with COVID-19 on the respiratory microbiome: A narrative review

Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, has affected millions of individuals with various implications. Consistent with the crucial role of the microbiome in determining health and disease in humans, various studies have investigated the gut and respiratory microbiome effect on the COVID-19. Microbiota dysbiosis might support the entry, replication, and establishment of SARS-CoV-2 infection by modulating various mechanisms. One of the main mechanisms that the modulation of respiratory microbiota composition during the COVID-19 infection affects the magnitude of the disease is changes in innate and acquired immune responses, including inflammatory markers and cytokines and B- and T-cells. The diversity of respiratory microbiota in COVID-19 patients is controversial; some studies reported low microbial diversity, while others found high diversity, suggesting the role of respiratory microbiota in this disease. Modulating microbiota diversity and profile by supplementations and nutrients can be applied prophylactic and therapeutic in combating COVID-19. Here, we discussed the lung microbiome dysbiosis during various lung diseases and its interaction with immune cells, focusing on COVID-19.

Integrated computational approach towards identification of HSPG and ACE2 mimicking moieties for SARS-CoV-2 inhibition

A key step to inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is to prevent the entry of the virus into the host cells. The receptor-binding domains (RBDs) of spike proteins of SARS-CoV and other human coronaviruses utilize heparan sulfate proteoglycans (HSPGs) as the primary receptors for their accumulation on the cell surface and then scan for binding to the main entry receptor angiotensin-converting enzyme 2 (ACE2). SARS-CoV and SARS-CoV-2 share structurally similar RBDs and therefore, it is possible that SARS-COV-2 primarily binds to HSPGs followed by binding to the ACE2 receptors. A promising strategy to inhibit virus infection is to circulate exogenous bioactive moieties structurally mimicking cellular HSPG and ACE2 which act as decoy receptors binding to SARS-CoV-2 and competitively inhibit virus entry to the host cells mediated by cellular-bound HSPG and ACE2. Using a molecular docking tool, we identified carboxymethyl benzyl amide sulfonate (CMBS) and polyanetholesulfonic acid (PAS) as the suitable HSPG mimicking ligands, and Paenibacillus sp. B38-derived carboxypeptidase (B38-CAP) and Bacillus subtilis-derived carboxypeptidase (BS-CAP) as the potential ACE2-like enzymes having a strong binding affinity to the spike proteins as that of cellular HSPG and ACE2. Further, the binding stability and compactness of these moieties with SARS-CoV-2 were analyzed through molecular dynamics (MD) simulations, and the results indicated that these moieties form well-stable complexes with the RBD of spike proteins. The identified moieties could be conjugated to the surfaces of non-toxic nanoparticles to provide multiple interactions to efficiently shield SARS-CoV-2, and inhibit viral entry to the host cells.

An update on angiotensin-converting enzyme 2 structure/functions, polymorphism, and duplicitous nature in the pathophysiology of coronavirus disease 2019: Implications for vascular and coagulation disease associated with severe acute respiratory syndrome coronavirus infection

It has been known for many years that the angiotensin-converting enzyme 2 (ACE2) is a cell surface enzyme involved in the regulation of blood pressure. More recently, it was proven that the severe acute respiratory syndrome coronavirus (SARS-CoV-2) interacts with ACE2 to enter susceptible human cells. This functional duality of ACE2 tends to explain why this molecule plays such an important role in the clinical manifestations of coronavirus disease 2019 (COVID-19). At the very start of the pandemic, a publication from our Institute (entitled "ACE2 receptor polymorphism: susceptibility to SARS-CoV-2, hypertension, multi-organ failure, and COVID-19 disease outcome"), was one of the first reviews linking COVID-19 to the duplicitous nature of ACE2. However, even given that COVID-19 pathophysiology may be driven by an imbalance in the renin-angiotensin system (RAS), we were still far from understanding the complexity of the mechanisms which are controlled by ACE2 in different cell types. To gain insight into the physiopathology of SARS-CoV-2 infection, it is essential to consider the polymorphism and expression levels of the ACE2 gene (including its alternative isoforms). Over the past 2 years, an impressive amount of new results have come to shed light on the role of ACE2 in the pathophysiology of COVID-19, requiring us to update our analysis. Genetic linkage studies have been reported that highlight a relationship between ACE2 genetic variants and the risk of developing hypertension. Currently, many research efforts are being undertaken to understand the links between ACE2 polymorphism and the severity of COVID-19. In this review, we update the state of knowledge on the polymorphism of ACE2 and its consequences on the susceptibility of individuals to SARS-CoV-2. We also discuss the link between the increase of angiotensin II levels among SARS-CoV-2-infected patients and the development of a cytokine storm associated microvascular injury and obstructive thrombo-inflammatory syndrome, which represent the primary causes of severe forms of COVID-19 and lethality. Finally, we summarize the therapeutic strategies aimed at preventing the severe forms of COVID-19 that target ACE2. Changing paradigms may help improve patients' therapy.

Ang II (Angiotensin II)-Induced FGFR1 (Fibroblast Growth Factor Receptor 1) Activation in Tubular Epithelial Cells Promotes Hypertensive Kidney Fibrosis and Injury

BACKGROUND

Elevated Ang II (angiotensin II) level leads to a range of conditions, including hypertensive kidney disease. Recent evidences indicate that FGFR1 (fibroblast growth factor receptor 1) signaling may be involved in kidney injuries. In this study, we determined whether Ang II alters FGFR1 signaling to mediate renal dysfunction.

METHODS

Human archival kidney samples from patients with or without hypertension were examined. Multiple genetic and pharmacological approaches were used to investigate FGFR1-mediated signaling in tubular epithelial NRK-52E cells in response to Ang II stimulation. C57BL/6 mice were infused with Ang II for 28 days to develop hypertensive kidney disease. Mice were treated with either adeno-associated virus expressing FGFR1 shRNA or FGFR1 inhibitor AZD4547.

RESULTS

Kidney specimens from subjects with hypertension and mice challenged with Ang II have increased FGFR1 activity in renal epithelial cells. Renal epithelial cells in culture initiate extracellular matrix programming in response to Ang II, through the activation of FGFR1, which is independent of both AT1R (angiotensin II receptor type 1) and AT2R (angiotensin II receptor type 2). The RNA sequencing analysis indicated that disrupting FGFR1 suppresses Ang II-induced fibrogenic responses in epithelial cells. Mechanistically, Ang II-activated FGFR1 leads to STAT3 (signal transducer and activator of transcription 3) activation, which is responsible for fibrogenic factor expression in kidneys. In the mouse model of hypertensive kidney disease, genetic knockdown of FGFR1 or pharmacological inhibition of its activity protected kidneys from dysfunction and fibrosis upon Ang II challenge.

CONCLUSIONS

Our studies uncover a novel mechanism causing renal fibrosis in hypertension and indicate FGFR1 as a potential target to preserve renal function and integrity.

ACE2-like enzyme B38-CAP suppresses abdominal sepsis and severe acute lung injury

Angiotensin-converting enzyme 2 (ACE2) is the carboxypeptidase to degrade angiotensin II (Ang II) to angiotensin 1–7 (Ang 1–7) and improves the pathologies of cardiovascular disease and acute respiratory distress syndrome (ARDS)/acute lung injury. B38-CAP is a bacteria-derived ACE2-like carboxypeptidase as potent as human ACE2 and ameliorates hypertension, heart failure and SARS-CoV-2-induced lung injury in mice. Recombinant B38-CAP is prepared with E. coli protein expression system more efficiently than recombinant soluble human ACE2. Here we show therapeutic effects of B38-CAP on abdominal sepsis- or acid aspiration-induced acute lung injury. ACE2 expression was downregulated in the lungs of mice with cecal ligation puncture (CLP)-induced sepsis or acid-induced lung injury thereby leading to upregulation of Ang II levels. Intraperitoneal injection of B38-CAP significantly decreased Ang II levels while upregulated angiotensin 1–7 levels. B38-CAP improved survival rate of the mice under sepsis. B38-CAP suppressed the pathologies of lung inflammation, improved lung dysfunction and downregulated elevated cytokine mRNA levels in the mice with acute lung injury. Thus, systemic treatment with an ACE2-like enzyme might be a potential therapeutic strategy for the patients with severe sepsis or ARDS.

Zinc transport via ZNT5-6 and ZNT7 is critical for cell surface glycosylphosphatidylinositol-anchored protein expression

Glycosylphosphatidylinositol (GPI)-anchored proteins play crucial roles in various enzyme activities, cell signaling and adhesion, and immune responses. While the molecular mechanism underlying GPI-anchored protein biosynthesis has been well studied, the role of zinc transport in this process has not yet been elucidated. Zn transporter (ZNT) proteins mobilize cytosolic zinc to the extracellular space and to intracellular compartments. Here, we report that the early secretory pathway ZNTs (ZNT5–ZNT6 heterodimers [ZNT5-6] and ZNT7–ZNT7 homodimers [ZNT7]), which supply zinc to the lumen of the early secretory pathway compartments are essential for GPI-anchored protein expression on the cell surface. We show, using overexpression and gene disruption/re-expression strategies in cultured human cells, that loss of ZNT5-6 and ZNT7 zinc transport functions results in significant reduction in GPI-anchored protein levels similar to that in mutant cells lacking phosphatidylinositol glycan anchor biosynthesis (PIG) genes. Furthermore, medaka fish with disrupted Znt5 and Znt7 genes show touch-insensitive phenotypes similar to zebrafish Pig mutants. These findings provide a previously unappreciated insight into the regulation of GPI-anchored protein expression and protein quality control in the early secretory pathway.

Angiotensin-converting enzyme 2 (ACE2): Two decades of revelations and re-evaluation

Angiotensin-converting enzyme-2, or ACE2, is primarily a zinc-dependent peptidase and ectoenzyme expressed in numerous cell types and functioning as a counterbalance to ACE in the renin-angiotensin system. It was discovered 21 years ago more than 40 years after the discovery of ACE itself. Its primary physiological activity is believed to be in the conversion of angiotensin II to the vasodilatory angiotensin-(1-7) acting through the Mas receptor. As such it has been implicated in numerous pathological conditions, largely in a protective mode which has led to the search for ACE2 activatory mechanisms. ACE2 has a diverse substrate specificity allowing its participation in multiple peptide pathways. It also regulates aspects of amino acid transport through its homology with a membrane protein, collectrin. It also serves as a viral receptor for the SARS virus, and subsequently SARS-CoV2, driving the current COVID-19 pandemic. ACE2 therefore provides a therapeutic target for the treatment of COVID and understanding the biological events following viral binding can provide insight into the multiple pathologies caused by the virus, particularly inflammatory and vascular. In part this may relate to the ability of ACE2, like ACE, to be shed from the cell membrane. The shed form of ACE2 (sACE2) may be a factor in determining susceptibility to certain COVID pathologies. Hence, for just over 20 years, ACE2 has provided numerous surprises in the field of vasoactive peptides with, no doubt, more to come but it is its central role in COVID pathology that is producing the current intense interest in its biology.

Effective Regulation of Gut Microbiota With Probiotics and Prebiotics May Prevent or Alleviate COVID-19 Through the Gut-Lung Axis

Coronavirus disease 2019 (COVID-19) can disrupt the gut microbiota balance, and patients usually have intestinal disorders. The intestine is the largest immune organ of the human body, and gut microbes can affect the immune function of the lungs through the gut-lung axis. Many lines of evidence support the role of beneficial bacteria in enhancing human immunity, preventing pathogen colonization, and thereby reducing the incidence and severity of infection. In this article, we review the possible approach of modulating microbiota to help prevent and treat respiratory tract infections, including COVID-19, and discuss the possibility of using probiotics and prebiotics for this purpose. We also discuss the mechanism by which intestinal micro-flora regulate immunity and the effects of probiotics on the intestinal micro-ecological balance. Based on this understanding, we propose the use of probiotics and prebiotics to modulate gut microbiota for the prevention or alleviation of COVID-19 through the gut-lung axis.

Drugs Modulating Renin-Angiotensin System in COVID-19 Treatment

A massive worldwide vaccination campaign constitutes the main tool against the COVID-19 pandemic. However, drug treatments are also necessary. Antivirals are the most frequently considered treatments. However, strategies targeting mechanisms involved in disease aggravation may also be effective. A major role of the tissue renin-angiotensin system (RAS) in the pathophysiology and severity of COVID-19 has been suggested. The main link between RAS and COVID-19 is angiotensin-converting enzyme 2 (ACE2), a central RAS component and the primary binding site for SARS-CoV-2 that facilitates the virus entry into host cells. An initial suggestion that the susceptibility to infection and disease severity may be enhanced by angiotensin type-1 receptor blockers (ARBs) and ACE inhibitors (ACEIs) because they increase ACE2 levels, led to the consideration of discontinuing treatments in thousands of patients. More recent experimental and clinical data indicate that ACEIs and, particularly, ARBs can be beneficial for COVID-19 outcome, both by reducing inflammatory responses and by triggering mechanisms (such as ADAM17 inhibition) counteracting viral entry. Strategies directly activating RAS anti-inflammatory components such as soluble ACE2, Angiotensin 1-7 analogues, and Mas or AT2 receptor agonists may also be beneficial. However, while ACEIs and ARBs are cheap and widely used, the second type of strategies are currently under study.

Angiotensin-Converting Enzyme 2 (ACE2) in the Pathogenesis of ARDS in COVID-19

Seventeen years after the epidemic of SARS coronavirus, a novel coronavirus SARS-CoV-2-emerged resulting in an unprecedented pandemic. Angiotensin-converting enzyme 2 (ACE2) is an essential receptor for cell entry of SARS-CoV-2 as well as the SARS coronavirus. Despite many similarities to SARS coronavirus, SARS-CoV-2 exhibits a higher affinity to ACE2 and shows higher infectivity and transmissibility, resulting in explosive increase of infected people and COVID-19 patients. Emergence of the variants harboring mutations in the receptor-binding domain of the Spike protein has drawn critical attention to the interaction between ACE2 and Spike and the efficacies of vaccines and neutralizing antibodies. ACE2 is a carboxypeptidase which degrades angiotensin II, B1-bradykinin, or apelin, and thereby is a critical regulator of cardiovascular physiology and pathology. In addition, the enzymatic activity of ACE2 is protective against acute respiratory distress syndrome (ARDS) caused by viral and non-viral pneumonias, aspiration, or sepsis. Upon infection, both SARS-CoV-2 and SARS coronaviruses downregulates ACE2 expression, likely associated with the pathogenesis of ARDS. Thus, ACE2 is not only the SARS-CoV-2 receptor but might also play an important role in multiple aspects of COVID-19 pathogenesis and possibly post-COVID-19 syndromes. Soluble forms of recombinant ACE2 are currently utilized as a pan-variant decoy to neutralize SARS-CoV-2 and a supplementation of ACE2 carboxypeptidase activity. Here, we review the role of ACE2 in the pathology of ARDS in COVID-19 and the potential application of recombinant ACE2 protein for treating COVID-19.

Biotechnological Applications of Probiotics: A Multifarious Weapon to Disease and Metabolic Abnormality

Consumption of live microorganisms "Probiotics" for health benefits and well-being is increasing worldwide. Their use as a therapeutic approach to confer health benefits has fascinated humans for centuries; however, its conceptuality gradually evolved with methodological advancement, thereby improving our understanding of probiotics-host interaction. However, the emerging concern regarding safety aspects of live microbial is enhancing the interest in non-viable or microbial cell extracts, as they could reduce the risks of microbial translocation and infection. Due to technical limitations in the production and formulation of traditionally used probiotics, the scientific community has been focusing on discovering new microbes to be used as probiotics. In many scientific studies, probiotics have been shown as potential tools to treat metabolic disorders such as obesity, type-2 diabetes, non-alcoholic fatty liver disease, digestive disorders (e.g., acute and antibiotic-associated diarrhea), and allergic disorders (e.g., eczema) in infants. However, the mechanistic insight of strain-specific probiotic action is still unknown. In the present review, we analyzed the scientific state-of-the-art regarding the mechanisms of probiotic action, its physiological and immuno-modulation on the host, and new direction regarding the development of next-generation probiotics. We discuss the use of recently discovered genetic tools and their applications for engineering the probiotic bacteria for various applications including food, biomedical applications, and other health benefits. Finally, the review addresses the future development of biological techniques in combination with clinical and preclinical studies to explain the molecular mechanism of action, and discover an ideal multifunctional probiotic bacterium.

ACE2-like carboxypeptidase B38-CAP protects from SARS-CoV-2-induced lung injury

Angiotensin-converting enzyme 2 (ACE2) is a receptor for cell entry of SARS-CoV-2, and recombinant soluble ACE2 protein inhibits SARS-CoV-2 infection as a decoy. ACE2 is a carboxypeptidase that degrades angiotensin II, thereby improving the pathologies of cardiovascular disease or acute lung injury. Here we show that B38-CAP, an ACE2-like enzyme, is protective against SARS-CoV-2-induced lung injury. Endogenous ACE2 expression is downregulated in the lungs of SARS-CoV-2-infected hamsters, leading to elevation of angiotensin II levels. Recombinant Spike also downregulates ACE2 expression and worsens the symptoms of acid-induced lung injury. B38-CAP does not neutralize cell entry of SARS-CoV-2. However, B38-CAP treatment improves the pathologies of Spike-augmented acid-induced lung injury. In SARS-CoV-2-infected hamsters or human ACE2 transgenic mice, B38-CAP significantly improves lung edema and pathologies of lung injury. These results provide the first in vivo evidence that increasing ACE2-like enzymatic activity is a potential therapeutic strategy to alleviate lung pathologies in COVID-19 patients.

Endogenous ACE2 is a receptor for SARS-CoV-2 and a recombinant soluble ACE2 protein can inhibit SARS-CoV-2 infection acting as a decoy. Here the authors show that B38-CAP, an ACE2-like enzyme but not a decoy for the virus, is protective against SARS-CoV-2-induced lung injury in animal models.

Physiopathology and prospectives for therapeutic treatment of pulmonary fibrotic state in COVID-19 patients

The COVID-19 global pandemic has caused about 4,30 Mln deaths. Recently the first vaccines have been licensed, representing the most powerful weapon available to stop the pandemic. The COVID-19 viral infection in the most severe cases can cause severe lung lesions with the presence of fibrotic tissue. Even among cured individuals, the presence of pulmonary fibrotic tissue may be the major cause of long-term complications of COVID-19 requiring antifibrotic therapeutic treatment even in the post-COVID-19 infection phase to accelerate the healing process and fully recover lung function. This article reviews the fibrogenic mechanism of SARS-CoV-2-induced viral damage and the antifibrotic treatments indicated to treat sequelae post COVID-19 infection.

Modulation of Gut Microbiota for the Prevention and Treatment of COVID-19

The gut microbiota is well known to exert multiple benefits on human health including protection from disease causing pathobiont microbes. It has been recognized that healthy intestinal microbiota is of great importance in the pathogenesis of COVID-19. Gut dysbiosis caused by various reasons is associated with severe COVID-19. Therefore, the modulation of gut microbiota and supplementation of commensal bacterial metabolites could reduce the severity of COVID-19. Many approaches have been studied to improve gut microbiota in COVID-19 including probiotics, bacterial metabolites, and prebiotics, as well as nutraceuticals and trace elements. So far, 19 clinical trials for testing the efficacy of probiotics and synbiotics in COVID-19 prevention and treatment are ongoing. In this narrative review, we summarize the effects of various approaches on the prevention and treatment of COVID-19 and discuss associated mechanisms.

Scientific Hypothesis for Treatment of COVID-19's Lung Lesions by Adjusting ACE/ACE2 Imbalance

In March 2019 began the global pandemic COVID-19 caused by the new Coronavirus SARS-CoV-2. The first cases of SARS-CoV-2 infection occurred in November-19 in Wuhan, China. The preventive measures taken did not prevent the rapid spread of the virus to all countries around the world. To date, there are about 2.54 million deaths, effective vaccines are in clinical trials. SARS-CoV-2 uses the ACE-2 protein as an intracellular gateway. ACE-2 is a key component of the Renin Angiotensin (RAS) system, a key regulator of cardiovascular function. Considering the key role of ACE-2 in COVID-19 infection, both as an entry receptor and as a protective role, especially for the respiratory tract, and considering the variations of ACE-2 and ACE during the stages of viral infection, it is clear the important role that the pharmacological regulation of RAS and ACE-2 can assume. This biological knowledge suggests different pharmacological approaches to treat COVID-19 by modulating RAS, ACE-2 and the ACE/ACE2 balance that we describe in this article.

Probiotics in Prevention and Treatment of COVID-19: Current Perspective and Future Prospects

Saving lives and flattening the curve are the foremost priorities during the ongoing pandemic spread of SARS-CoV-2. Developing cutting-edge technology and collating available evidence would support frontline health teams. Nutritional adequacy improves general health and immunity to prevent and assuage infections. This review aims to outline the potential role of probiotics in fighting the COVID-19 by covering recent evidence on the association between microbiota, probiotics, and COVID-19, the role of probiotics as an immune-modulator and antiviral agent. The high basic reproduction number (R0) of SARS-CoV-2, absence of conclusive remedies, and the pleiotropic effect of probiotics in fighting influenza and other coronaviruses together favour probiotics supplements. However, further support from preclinical and clinical studies and reviews outlining the role of probiotics in COVID-19 are critical. Results are awaited from many ongoing clinical trials investigating the benefits of probiotics in COVID-19.

Acidic preconditioning reduces lipopolysaccharide-induced acute lung injury by upregulating the expression of angiotensin-converting enzyme 2

Acid preconditioning (APC) through carbon dioxide inhalation can exert protective effects during acute lung injury (ALI) triggered by ischemia-reperfusion. Angiotensin-converting enzyme 2 (ACE2) has been identified as a receptor for severe acute respiratory syndrome coronavirus and the novel coronavirus disease-19. Downregulation of ACE2 plays an important role in the pathogenesis of severe lung failure after viral or bacterial infections. The aim of the present study was to examine the anti-inflammatory mechanism through which APC alleviates lipopolysaccharide (LPS)-induced ALI in vivo and in vitro. The present results demonstrated that LPS significantly downregulated the expression of ACE2, while APC significantly reduced LPS-induced ALI and provided beneficial effects. In addition, bioinformatics analysis indicated that microRNA (miR)-200c-3p directly targeted the 3'untranslated region of ACE2 and regulated the expression of ACE2 protein. LPS exposure inhibited the expression of ACE2 protein in A549 cells by upregulating the levels of miR-200c-3p. However, APC inhibited the upregulation of miR-200c-3p induced by LPS, as well as the downregulation of ACE2 protein, through the NF-κB pathway. In conclusion, although LPS can inhibit the expression of ACE2 by upregulating the levels of miR-200c-3p through the NF-κB pathway, APC inhibited this effect, thus reducing inflammation during LPS-induced ALI.

The role of SARS-CoV-2 target ACE2 in cardiovascular diseases

SARS-CoV-2, the virus responsible for the global coronavirus disease (COVID-19) pandemic, attacks multiple organs of the human body by binding to angiotensin-converting enzyme 2 (ACE2) to enter cells. More than 20 million people have already been infected by the virus. ACE2 is not only a functional receptor of COVID-19 but also an important endogenous antagonist of the renin-angiotensin system (RAS). A large number of studies have shown that ACE2 can reverse myocardial injury in various cardiovascular diseases (CVDs) as well as is exert anti-inflammatory, antioxidant, anti-apoptotic and anticardiomyocyte fibrosis effects by regulating transforming growth factor beta, mitogen-activated protein kinases, calcium ions in cells and other major pathways. The ACE2/angiotensin-(1-7)/Mas receptor axis plays a decisive role in the cardiovascular system to combat the negative effects of the ACE/angiotensin II/angiotensin II type 1 receptor axis. However, the underlying mechanism of ACE2 in cardiac protection remains unclear. Some approaches for enhancing ACE2 expression in CVDs have been suggested, which may provide targets for the development of novel clinical therapies. In this review, we aimed to identify and summarize the role of ACE2 in CVDs.

Humanized COVID-19 decoy antibody effectively blocks viral entry and prevents SARS-CoV-2 infection

To circumvent the devastating pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, a humanized decoy antibody (ACE2-Fc fusion protein) was designed to target the interaction between viral spike protein and its cellular receptor, angiotensin-converting enzyme 2 (ACE2). First, we demonstrated that ACE2-Fc could specifically abrogate virus replication by blocking the entry of SARS-CoV-2 spike-expressing pseudotyped virus into both ACE2-expressing lung cells and lung organoids. The impairment of viral entry was not affected by virus variants, since efficient inhibition was also observed in six SARS-CoV-2 clinical strains, including the D614G variants which have been shown to exhibit increased infectivity. The preservation of peptidase activity also enables ACE2-Fc to reduce the angiotensin II-mediated cytokine cascade. Furthermore, this Fc domain of ACE2-Fc was shown to activate NK cell degranulation after co-incubation with Spike-expressing H1975 cells. These promising characteristics potentiate the therapeutic prospects of ACE2-Fc as an effective treatment for COVID-19.

SARS-CoV-2 microbiome dysbiosis linked disorders and possible probiotics role

In December 2019, a pneumonia outbreak of unknown etiology was reported which caused panic in Wuhan city of central China, which was later identified as Coronavirus disease (COVID-19) caused by a novel coronavirus, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) by the Chinese Centre for Disease Control and Prevention (CDC) and WHO. To date, the SARS-CoV-2 spread has already become a global pandemic with a considerable death toll. The associated symptoms of the COVID-19 infection varied with increased inflammation as an everyday pathological basis. Among various other symptoms such as fever, cough, lethargy, gastrointestinal (GI) symptoms included diarrhea and IBD with colitis, have been reported. Currently, there is no sole cure for COVID-19, and researchers are actively engaged to search out appropriate treatment and develop a vaccine for its prevention. Antiviral for controlling viral load and corticosteroid therapy for reducing inflammation seems to be inadequate to control the fatality rate. Based on the available related literature, which documented GI symptoms with diarrhea, inflammatory bowel diseases (IBD) with colitis, and increased deaths in the intensive care unit (ICU), conclude that dysbiosis occurs during SARS-COV-2 infection as the gut-lung axis cannot be ignored. As probiotics play a therapeutic role for GI, IBD, colitis, and even in viral infection. So, we assume that the inclusion of studies to investigate gut microbiome and subsequent therapies such as probiotics might help decrease the inflammatory response of viral pathogenesis and respiratory symptoms by strengthening the host immune system, amelioration of gut microbiome, and improvement of gut barrier function.

Novel therapeutics for the treatment of hypertension and its associated complications: peptide- and nonpeptide-based strategies

The renin-angiotensin-aldosterone system (RAAS) is responsible for maintaining blood pressure and vascular tone. Modulation of the RAAS, therefore, interferes with essential cellular processes and leads to high blood pressure, oxidative stress, inflammation, fibrosis, and hypertrophy. Consequently, these conditions cause fatal cardiovascular and renal complications. Thus, the primary purpose of hypertension treatment is to diminish or inhibit overactivated RAAS. Currently available RAAS inhibitors have proven effective in reducing blood pressure; however, beyond hypertension, they have failed to treat end-target organ injury. In addition, RAAS inhibitors have some intolerable adverse effects, such as hyperkalemia and hypotension. These gaps in the available treatment for hypertension require further investigation of the development of safe and effective therapies. Current research is focused on the combination of existing and novel treatments that neutralize the angiotensin II type I (AT1) receptor-mediated action of the angiotensin II peptide. Preclinical studies of peptide- and nonpeptide-based therapeutic agents demonstrate their conspicuous impact on the treatment of cardiovascular diseases in animal models. In this review, we will discuss novel therapeutic agents being developed as RAAS inhibitors that show prominent effects in both preclinical and clinical studies. In addition, we will also highlight the need for improvement in the efficacy of existing drugs in the absence of new prominent antihypertensive drugs.

The Two-Way Switch Role of ACE2 in the Treatment of Novel Coronavirus Pneumonia and Underlying Comorbidities

December 2019 saw the emergence of the coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which has spread across the globe. The high infectivity and ongoing mortality of SARS-CoV-2 emphasize the demand of drug discovery. Angiotensin-converting enzyme II (ACE2) is the functional receptor for SARS-CoV-2 entry into host cells. ACE2 exists as a membrane-bound protein on major viral target pulmonary epithelial cells, and its peptidase domain (PD) interacts SARS-CoV-2 spike protein with higher affinity. Therefore, targeting ACE2 is an important pharmacological intervention for a SARS-CoV-2 infection. In this review, we described the two-way switch role of ACE2 in the treatment of novel coronavirus pneumonia and underlying comorbidities, and discussed the potential effect of the ACE inhibitor and angiotensin receptor blocker on a hypertension patient with the SARS-CoV-2 infection. In addition, we analyzed the S-protein-binding site on ACE2 and suggested that blocking hot spot-31 and hot spot-353 on ACE2 could be a therapeutic strategy for preventing the spread of SARS-CoV-2. Besides, the recombinant ACE2 protein could be another potential treatment option for SARS-CoV-2 induced acute severe lung failure. This review could provide beneficial information for the development of anti-SARS-CoV-2 agents via targeting ACE2 and the clinical usage of renin-angiotensin system (RAS) drugs for novel coronavirus pneumonia treatment.

Perspectives: potential therapeutic approach with inhalation of ACE2-derived peptides for SARS-CoV-2 infection

OBJECTIVE

ACE2 is crucially involved in the infection sustained by SARS-CoV-2, as it allows the entry of the virus into target cells while counteracting local inflammation, oxidative stress, and fibrosis. In this narrative review, we aim to discuss the usefulness of ACE2-derived peptides in the infection sustained by SARS-CoV-2.

METHODS

A total of 49 papers pertinent to the purpose of the review were selected from the PubMed and Google Scholar databases. Clinical trials registered at ClinicalTrials.gov and dealing with the use of ACE2-derived medications in COVID-19 were also searched and discussed.

RESULTS

Preclinical and clinical evidence shows that drugs mimicking or potentiating the effects of ACE2 may reduce the viral load and dampen the inflammatory and fibrotic pathways leading to respiratory distress. ACE2-derived therapeutic peptides may have a better pharmacokinetic and pharmacodynamic profile than other ACE2-based medications. They could be easily screened through peptide libraries and chemically modified in order to ameliorate the pharmacological properties. Furthermore, their local administration via an intranasal delivery or inhalation may reduce the risk of systemic side effects, thus conferring a good safety profile.

CONCLUSION

ACE2-derived peptides may play a dual beneficial role in COVID-19, by either preventing virus spread or inhibiting the secretion of pro-inflammatory mediators in airways. Viral, host, and environmental factors may affect the effectiveness of this therapeutic approach to a various extent and represent therefore a matter of investigation for future studies.

Review article: Probiotics, prebiotics and dietary approaches during COVID-19 pandemic

Background

Patients with COVID-19 caused by SARS-CoV-2 exhibit diverse clinical manifestations and severity including enteric involvement. Commensal gut bacteria can contribute to defense against potential pathogens by promoting beneficial immune interactions. Interventions targeting the gut microbiome may have systemic anti-viral effects in SARS-CoV-2 infection.

Scope and approach

To summarise alterations of gut microbiota in patients with COVID-19 including impact of specific bacteria on disease severity, discuss current knowledge on the role of probiotics, prebiotics and dietary approaches including vitamin D in preventing and reducing disease susceptibility and review clinical studies using probiotics to target coronavirus. A literature review on SARS-CoV-2, COVID-19, gut microbiome and immunity was undertaken and relevant literature was summarised and critically examined.

Key findings and conclusions

Integrity of gut microbiome was perturbed in SARS-CoV-2 infections and associated with disease severity. Poor prognosis in SARS-CoV-2 infection was observed in subjects with underlying co-morbidities who had increased gut permeability and reduced gut microbiome diversity. Dietary microbes, including probiotics or selected prebiotics of Chinese origin, had anti-viral effects against other forms of coronavirus, and could positively impact host immune functions during SARS-CoV-2 infection. Numerous studies are investigating the role of probiotics in preventing and reducing susceptibility to SARS-CoV-2 infection in healthcare workers, household contacts and affected patients. An approach to strengthen intestinal barrier and lower pro-inflammatory states by adopting a more diversified diet during COVID-19 pandemic.

SARS-CoV-2 infection is associated with immune dysfunction and gut microbiota alterations. Delineating mechanisms of probiotics, prebiotics and diet with anti-SARS-CoV-2 immunity present opportunities for discovery of microbial therapeutics to prevent and treat COVID-19.

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SARS-CoV-2 infection resulted in immune dysfunction and gut microbiota alterations.

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Probiotics or prebiotics could improve host immune functions during the infection.

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Enhance gut barrier by diversified diet was recommended during COVID-19 pandemic.

COVID-19 update: The race to therapeutic development

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), represents an unprecedented challenge to global public health. At the time of this review, COVID-19 has been diagnosed in over 40 million cases and associated with 1.1 million deaths worldwide. Current management strategies for COVID-19 are largely supportive, and while there are more than 2000 interventional clinical trials registered with the U.S. National Library of Medicine (clinicaltrials.gov), results that can clarify benefits and risks of candidate therapies are only gradually becoming available. We herein describe recent advances in understanding SARS-CoV-2 pathobiology and potential therapeutic targets that are involved in viral entry into host cells, viral spread in the body, and the subsequent COVID-19 progression. We highlight two major lines of therapeutic strategies for COVID-19 treatment: 1) repurposing the existing drugs for use in COVID-19 patients, such as antiviral medications (e.g., remdesivir) and immunomodulators (e.g., dexamethasone) which were previously approved for other disease conditions, and 2) novel biological products that are designed to target specific molecules that are involved in SARS-CoV-2 viral entry, including neutralizing antibodies against the spike protein of SARS-CoV-2, such as REGN-COV2 (an antibody cocktail), as well as recombinant human soluble ACE2 protein to counteract SARS-CoV-2 binding to the transmembrane ACE2 receptor in target cells. Finally, we discuss potential drug resistance mechanisms and provide thoughts regarding clinical trial design to address the diversity in COVID-19 clinical manifestation. Of note, preventive vaccines, cell and gene therapies are not within the scope of the current review.

Update on relevant trypanosome peptidases: Validated targets and future challenges

Trypanosoma cruzi, the agent of the American Trypanosomiasis, Chagas disease, and Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense, the agents of Sleeping sickness (Human African Trypanosomiasis, HAT), as well as Trypanosoma brucei brucei, the agent of the cattle disease nagana, contain cysteine, serine, threonine, aspartyl and metallo peptidases. The most abundant among these enzymes are the cysteine proteases from the Clan CA, the Cathepsin L-like cruzipain and rhodesain, and the Cathepsin B-like enzymes, which have essential roles in the parasites and thus are potential targets for chemotherapy. In addition, several other proteases, present in one or both parasites, have been characterized, and some of them are also promising candidates for the developing of new drugs. Recently, new inhibitors, with good selectivity for the parasite proteasomes, have been described and are very promising as lead compounds for the development of new therapies for these neglected diseases. This article is part of a Special Issue entitled: "Play and interplay of proteases in health and disease".

Should ACE2 be given a chance in COVID-19 therapeutics: A semi-systematic review of strategies enhancing ACE2

The severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) has resulted in almost 28 million cases of COVID-19 (Corona virus disease-2019) and more than 900000 deaths worldwide since December 2019. In the absence of effective antiviral therapy and vaccine, treatment of COVID-19 is largely symptomatic. By making use of its spike (S) protein, the virus binds to its primary human cell receptor, angiotensin converting enzyme 2 (ACE2) which is present in the pulmonary epithelial cells as well as other organs. SARS-CoV-2 may cause a downregulation of ACE2. ACE2 plays a protective role in the pulmonary system through its Mas-receptor and alamandine-MrgD-TGR7 pathways. Loss of this protective effect could be a major component of COVID-19 pathogenesis. An attractive strategy in SARS-CoV-2 therapeutics would be to augment ACE2 either directly by supplementation or indirectly through drugs which increase its levels or stimulate its downstream players. In this semi-systematic review, we have analysed the pathophysiological interplay between ACE and ACE2 in the cardiopulmonary system, the modulation of these two proteins by SARS-CoV-2, and potential therapeutic avenues targeting ACE-Ang II and ACE2-Ang (1-7) axes, that can be utilized against COVID-19 disease progression.

A rational roadmap for SARS-CoV-2/COVID-19 pharmacotherapeutic research and development: IUPHAR Review 29

In this review, we identify opportunities for drug discovery in the treatment of COVID-19 and, in so doing, provide a rational roadmap whereby pharmacology and pharmacologists can mitigate against the global pandemic. We assess the scope for targeting key host and viral targets in the mid-term, by first screening these targets against drugs already licensed, an agenda for drug repurposing, which should allow rapid translation to clinical trials. A simultaneous, multi-pronged approach using conventional drug discovery methods aimed at discovering novel chemical and biological means of targeting a short list of host and viral entities which should extend the arsenal of anti-SARS-CoV-2 agents. This longer term strategy would provide a deeper pool of drug choices for future-proofing against acquired drug resistance. Second, there will be further viral threats, which will inevitably evade existing vaccines. This will require a coherent therapeutic strategy which pharmacology and pharmacologists are best placed to provide. 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.

Myocardial Injury at Early Stage and Its Association With the Risk of Death in COVID-19 Patients: A Hospital-Based Retrospective Cohort Study

Background: There are growing evidence demonstrating that coronavirus disease 2019 (COVID-19) is companied by acute myocardial injury. However, the associations of SARS-CoV-2-induced myocardial injury with the risk of death and prognosis after discharge in COVID-19 patients are unclear. Methods: This prospective cohort study analyzed 355 COVID-19 patients from two hospitals in different regions. Clinical and demographic information were collected and prognosis was followed up. Results: Of 355 hospitalized patients with COVID-19, 213 were mild, 90 severe, and 52 critically ill patients. On admission, 59 (16.7%) patients were with myocardial injury. Myocardial injury was more popular in critically ill patients. Univariate and multivariate logistic regression revealed that male, older age and comorbidity with hypertension were three crucial independent risk factors predicting myocardial injury of COVID-19 patients. Among 59 COVID-19 patients with myocardial injury, 25 (42.4%) died on average 10.9 days after hospitalization. Mortality was increased among COVID-19 patients with myocardial injury (42.4 vs. 3.38%, RR = 12.542, P < 0.001). Follow-up study observed that 4.67% COVID-19 patients with myocardial injury were not fully recovered in 14 days after discharge. Conclusion: Myocardial injury at early stage elevates mortality of COVID-19 patients. Male elderly patients with hypertension are more vulnerable to myocardial injury. SARS-CoV-2-induced myocardial injury has not completely recovered in 14 days after discharge.

Gut Microbiota Dysbiosis-Immune Hyperresponse-Inflammation Triad in Coronavirus Disease 2019 (COVID-19): Impact of Pharmacological and Nutraceutical Approaches

Coronavirus Disease 2019 (COVID-19) is a pandemic infection caused by a novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Patients present a complex clinical picture that, in severe cases, evolves to respiratory, hepatic, gastrointestinal, and neurological complications, and eventually death. The underlying pathophysiological mechanisms are complex and multifactorial and have been summarized as a hyperresponse of the immune system that originates an inflammatory/cytokine storm. In elderly patients, particularly in those with pre-existing cardiovascular, metabolic, renal, and pulmonary disorders, the disease is particularly severe, causing prolonged hospitalization at intensive care units (ICU) and an increased mortality rate. Curiously, the same populations have been described as more prone to a gut microbiota (GM) dysbiosis profile. Intestinal microflora plays a major role in many metabolic and immune functions of the host, including to educate and strengthen the immune system to fight infections, namely of viral origin. Notably, recent studies suggest the existence of GM dysbiosis in COVID-19 patients. This review article highlights the interplay between the triad GM dysbiosis-immune hyperresponse-inflammation in the individual resilience/fragility to SARS-CoV-2 infection and presents the putative impact of pharmacological and nutraceutical approaches on the triumvirate, with focus on GM.

Severe acute respiratory syndrome-coronavirus-2: Current advances in therapeutic targets and drug development

The current pandemic of severe acute respiratory syndrome‐coronavirus‐2 (SARS‐CoV‐2) has quickly emerged as a global health concern with government bodies worldwide taking drastic control measures. Understanding the virology of SARS‐CoV‐2, its molecular mechanisms, and its pathogenesis are required for a targeted therapeutic approach. In this review, we highlight the current molecular and drug advances that target SARS‐CoV‐2 at the genome level. We also summarize studies that therapeutically target the host angiotensin‐converting enzyme 2 and proteases. Finally, we summarize antibody‐mediated therapeutic approaches, as well as recent trends in vaccine development. Hence, the purpose of this study is to investigate different molecular targets in SARS‐CoV‐2 pathogenesis and their usefulness in developing strategies for drug development.

ACE2, the Receptor that Enables Infection by SARS-CoV-2: Biochemistry, Structure, Allostery and Evaluation of the Potential Development of ACE2 Modulators

Angiotensin converting enzyme 2 (ACE2) is the human receptor that interacts with the spike protein of coronaviruses, including the one that produced the 2020 coronavirus pandemic (COVID-19). Thus, ACE2 is a potential target for drugs that disrupt the interaction of human cells with SARS-CoV-2 to abolish infection. There is also interest in drugs that inhibit or activate ACE2, that is, for cardiovascular disorders or colitis. Compounds binding at alternative sites could allosterically affect the interaction with the spike protein. Herein, we review biochemical, chemical biology, and structural information on ACE2, including the recent cryoEM structures of full-length ACE2. We conclude that ACE2 is very dynamic and that allosteric drugs could be developed to target ACE2. At the time of the 2020 pandemic, we suggest that available ACE2 inhibitors or activators in advanced development should be tested for their ability to allosterically displace the interaction between ACE2 and the spike protein.

SARS-CoV-2 Treatment Approaches: Numerous Options, No Certainty for a Versatile Virus

SARS-CoV-2 is the most recent coronavirus which crossed the species barrier in 2019 and provoked a still ongoing and dangerous pandemic known as coronavirus disease 2019 (COVID-19). The SARS-CoV-2 infection has triggered an impressive amount of clinical and experimental studies to identify an effective and safe therapy to stop the pandemic spread. Hence, numerous trials and studies have scrutinized the analogies between SARS-CoV-2 and other corona viruses or the host-virus interactions and their similarities with immune system disorders. Still, the pathogenic mechanisms behind SARS-CoV-2 have been partially deciphered and the current therapies have not yet met the initial enthusiastic expectations. So far COVID-19 therapies have targeted various pathogenic mechanisms, namely the neutralization of ACE2 receptors or SARS-CoV-2 spike protein epitopes, the disruption of the endocytic pathways using hydroxychloroquine, arbidol, or anti-Janus kinase inhibitors, the inhibition of RNA-dependent RNA polymerase using nucleotide analogues such as remdesivir, immunosuppressive drugs or molecules acting on the immune response (corticoids, interferons, monoclonal antibodies against inflammatory cytokines, mesenchymal stem cells) and convalescent plasma administration together with numerous drugs with unproven effect against SARS-CoV-2 but with potential antiviral activities (antiretrovirals, antimalarial drugs, antibiotics, etc.). Nevertheless, these therapies have been associated with side effects and contradictory results. At the same time a specific SARS-CoV-2 vaccine is a long-term solution requiring clinical validation and important investments together with appropriate strategies to promote the confidence in the safety of the new vaccine. The article revises the current state of SARS-CoV-2 therapeutic options but advises towards a more cautious and individualized treatment approach centred on the clinical features, immune particularities, and the risk-benefit balance.

A comparison of COVID-19, SARS and MERS

In mid-December 2019, a novel atypical pneumonia broke out in Wuhan, Hubei Province, China and was caused by a newly identified coronavirus, initially termed 2019 Novel Coronavirus and subsequently severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As of 19 May 2020, a total of 4,731,458 individuals were reported as infected with SARS-CoV-2 among 213 countries, areas or territories with recorded cases, and the overall case-fatality rate was 6.6% (316,169 deaths among 4,731,458 recorded cases), according to the World Health Organization. Studies have shown that SARS-CoV-2 is notably similar to (severe acute respiratory syndrome coronavirus) SARS-CoV that emerged in 2002–2003 and Middle East respiratory syndrome coronavirus (MERS-CoV) that spread during 2012, and these viruses all contributed to global pandemics. The ability of SARS-CoV-2 to rapidly spread a pneumonia-like disease from Hubei Province, China, throughout the world has provoked widespread concern. The main symptoms of coronavirus disease 2019 (COVID-19) include fever, cough, myalgia, fatigue and lower respiratory signs. At present, nucleic acid tests are widely recommended as the optimal method for detecting SARS-CoV-2. However, obstacles remain, including the global shortage of testing kits and the presentation of false negatives. Experts suggest that almost everyone in China is susceptible to SARS-CoV-2 infection, and to date, there are no effective treatments. In light of the references published, this review demonstrates the biological features, spread, diagnosis and treatment of SARS-CoV-2 as a whole and aims to analyse the similarities and differences among SARS-CoV-2, SARS-CoV and MERS-CoV to provide new ideas and suggestions for prevention, diagnosis and clinical treatment.

Decoding SARS-CoV-2 hijacking of host mitochondria in COVID-19 pathogenesis

Because of the ongoing pandemic around the world, the mechanisms underlying the SARS-CoV-2-induced COVID-19 are subject to intense investigation. Based on available data for the SARS-CoV-1 virus, we suggest how CoV-2 localization of RNA transcripts in mitochondria hijacks the host cell's mitochondrial function to viral advantage. Besides viral RNA transcripts, RNA also localizes to mitochondria. SARS-CoV-2 may manipulate mitochondrial function indirectly, first by ACE2 regulation of mitochondrial function, and once it enters the host cell, open-reading frames (ORFs) such as ORF-9b can directly manipulate mitochondrial function to evade host cell immunity and facilitate virus replication and COVID-19 disease. Manipulations of host mitochondria by viral ORFs can release mitochondrial DNA (mtDNA) in the cytoplasm and activate mtDNA-induced inflammasome and suppress innate and adaptive immunity. We argue that a decline in ACE2 function in aged individuals, coupled with the age-associated decline in mitochondrial functions resulting in chronic metabolic disorders like diabetes or cancer, may make the host more vulnerable to infection and health complications to mortality. These observations suggest that distinct localization of viral RNA and proteins in mitochondria must play essential roles in SARS-CoV-2 pathogenesis. Understanding the mechanisms underlying virus communication with host mitochondria may provide critical insights into COVID-19 pathologies. An investigation into the SARS-CoV-2 hijacking of mitochondria should lead to novel approaches to prevent and treat COVID-19.

Decoding SARS-CoV-2 hijacking of host mitochondria in COVID-19 pathogenesis

Because of the ongoing pandemic around the world, the mechanisms underlying the SARS-CoV-2-induced COVID-19 are subject to intense investigation. Based on available data for the SARS-CoV-1 virus, we suggest how CoV-2 localization of RNA transcripts in mitochondria hijacks the host cell's mitochondrial function to viral advantage. Besides viral RNA transcripts, RNA also localizes to mitochondria. SARS-CoV-2 may manipulate mitochondrial function indirectly, first by ACE2 regulation of mitochondrial function, and once it enters the host cell, open-reading frames (ORFs) such as ORF-9b can directly manipulate mitochondrial function to evade host cell immunity and facilitate virus replication and COVID-19 disease. Manipulations of host mitochondria by viral ORFs can release mitochondrial DNA (mtDNA) in the cytoplasm and activate mtDNA-induced inflammasome and suppress innate and adaptive immunity. We argue that a decline in ACE2 function in aged individuals, coupled with the age-associated decline in mitochondrial functions resulting in chronic metabolic disorders like diabetes or cancer, may make the host more vulnerable to infection and health complications to mortality. These observations suggest that distinct localization of viral RNA and proteins in mitochondria must play essential roles in SARS-CoV-2 pathogenesis. Understanding the mechanisms underlying virus communication with host mitochondria may provide critical insights into COVID-19 pathologies. An investigation into the SARS-CoV-2 hijacking of mitochondria should lead to novel approaches to prevent and treat COVID-19.