RESUMEN
The transmembrane serine protease 2 (TMPRSS2) activates the outer structural proteins of a number of respiratory viruses including influenza A virus (IAV), parainfluenza viruses, and various coronaviruses for membrane fusion. Previous studies showed that TMPRSS2 interacts with the carboxypeptidase angiotensin-converting enzyme 2 (ACE2), a cell surface protein that serves as an entry receptor for some coronaviruses. Here, by using protease activity assays, we determine that ACE2 increases the enzymatic activity of TMPRSS2 in a non-catalytic manner. Furthermore, we demonstrate that ACE2 knockdown inhibits TMPRSS2-mediated cleavage of IAV hemagglutinin (HA) in Calu-3 human airway cells and suppresses virus titers 100- to 1.000-fold. Transient expression of ACE2 in ACE2-deficient cells increased TMPRSS2-mediated HA cleavage and IAV replication. ACE2 knockdown also reduced titers of MERS-CoV and prevented S cleavage by TMPRSS2 in Calu-3 cells. By contrast, proteolytic activation and multicycle replication of IAV with multibasic HA cleavage site typically cleaved by furin were not affected by ACE2 knockdown. Co-immunoprecipitation analysis revealed that ACE2-TMPRSS2 interaction requires the enzymatic activity of TMPRSS2 and the carboxypeptidase domain of ACE2. Together, our data identify ACE2 as a new co-factor or stabilizer of TMPRSS2 activity and as a novel host cell factor involved in proteolytic activation and spread of IAV in human airway cells. Furthermore, our data indicate that ACE2 is involved in the TMPRSS2-catalyzed activation of additional respiratory viruses including MERS-CoV.IMPORTANCEProteolytic cleavage of viral envelope proteins by host cell proteases is essential for the infectivity of many viruses and relevant proteases provide promising drug targets. The transmembrane serine protease 2 (TMPRSS2) has been identified as a major activating protease of several respiratory viruses, including influenza A virus. TMPRSS2 was previously shown to interact with angiotensin-converting enzyme 2 (ACE2). Here, we report the mechanistic details of this interaction. We demonstrate that ACE2 increases or stabilizes the enzymatic activity of TMPRSS2. Furthermore, we describe ACE2 involvement in TMPRSS2-catalyzed cleavage of the influenza A virus hemagglutinin and MERS-CoV spike protein in human airway cells. These findings expand our knowledge of the activation of respiratory viruses by TMPRSS2 and the host cell factors involved. In addition, our results could help to elucidate a physiological role for TMPRSS2.
Asunto(s)
Enzima Convertidora de Angiotensina 2 , Virus de la Influenza A , Pulmón , Proteolisis , Serina Endopeptidasas , Animales , Perros , Humanos , Enzima Convertidora de Angiotensina 2/deficiencia , Enzima Convertidora de Angiotensina 2/genética , Enzima Convertidora de Angiotensina 2/metabolismo , Biocatálisis , Línea Celular , Furina/metabolismo , Glicoproteínas Hemaglutininas del Virus de la Influenza/metabolismo , Virus de la Influenza A/crecimiento & desarrollo , Virus de la Influenza A/metabolismo , Pulmón/citología , Pulmón/virología , Coronavirus del Síndrome Respiratorio de Oriente Medio/metabolismo , Unión Proteica , Serina Endopeptidasas/metabolismo , Glicoproteína de la Espiga del Coronavirus/metabolismo , Internalización del Virus , Replicación ViralRESUMEN
SARS-CoV-2, the virus responsible for COVID-19, uses angiotensin converting enzyme 2 (ACE2) as its primary cell-surface receptor. ACE2 is a key enzyme in the counter-regulatory pathway of the broader renin-angiotensin system (RAS) that has been implicated in a broad array of human pathology. The RAS is composed of two competing pathways that work in opposition to each other: the "conventional" arm involving angiotensin converting enzyme (ACE) generating angiotensin-2 and the more recently identified ACE2 pathway that generates angiotensin (1-7). Following the original SARS pandemic, additional studies suggested that coronaviral binding to ACE2 resulted in downregulation of the membrane-bound enzyme. Given the similarities between the two viruses, many have posited a similar process with SARS-CoV-2. Proponents of this ACE2 deficiency model argue that downregulation of ACE2 limits its enzymatic function, thereby skewing the delicate balance between the two competing arms of the RAS. In this review we critically examine this model. The available data remain incomplete but are consistent with the possibility that the broad multisystem dysfunction of COVID-19 is due in large part to functional ACE2 deficiency leading to angiotensin imbalance with consequent immune dysregulation and endothelial cell dysfunction.
Asunto(s)
Enzima Convertidora de Angiotensina 2 , Angiotensinas , COVID-19 , Enzima Convertidora de Angiotensina 2/deficiencia , COVID-19/fisiopatología , Humanos , Pandemias , Sistema Renina-Angiotensina , SARS-CoV-2RESUMEN
Angiotensin-converting enzyme (ACE) and its homologue, ACE2, are commonly allied with hypertension, renin-angiotensin-aldosterone system pathway, and other cardiovascular system disorders. The recent pandemic of COVID-19 has attracted the attention of numerous researchers on ACE2 receptors, where the causative viral particle, SARS-CoV-2, is established to exploit these receptors for permitting their entry into the human cells. Therefore, studies on the molecular origin and pathophysiology of the cell response in correlation to the role of ACE2 receptors to these viruses are bringing novel theories. The varying level of manifestation and importance of ACE proteins, underlying irregularities and disorders, intake of specific medications, and persistence of assured genomic variants at the ACE genes are potential questions raising nowadays while observing the marked alteration in response to the SARS-CoV-2-infected patients. Therefore, the present review has focused on several raised opinions associated with the role of the ACE2 receptor and its impact on COVID-19 pathogenesis.
Asunto(s)
Enzima Convertidora de Angiotensina 2/metabolismo , Enzima Convertidora de Angiotensina 2/farmacología , Tratamiento Farmacológico de COVID-19 , SARS-CoV-2/patogenicidad , Lesión Pulmonar Aguda , Enzima Convertidora de Angiotensina 2/deficiencia , Enzima Convertidora de Angiotensina 2/uso terapéutico , Humanos , Hipertensión/tratamiento farmacológico , Glicoproteína de la Espiga del Coronavirus/metabolismoRESUMEN
The renin-angiotensin system (RAS) is a highly complex hormonal cascade that spans multiple organs and cell types to regulate solute and fluid balance along with cardiovascular function. Much of our current understanding of the functions of the RAS has emerged from a series of key studies in genetically-modified animals. Here, we review key findings from ground-breaking transgenic models, spanning decades of research into the RAS, with a focus on their use in studying blood pressure. We review the physiological importance of this regulatory system as evident through the examination of mouse models for several major RAS components: angiotensinogen, renin, ACE, ACE2, and the type 1 A angiotensin receptor. Both whole-animal and cell-specific knockout models have permitted critical RAS functions to be defined and demonstrate how redundancy and multiplicity within the RAS allow for compensatory adjustments to maintain homeostasis. Moreover, these models present exciting opportunities for continued discovery surrounding the role of the RAS in disease pathogenesis and treatment for cardiovascular disease and beyond.
Asunto(s)
Angiotensinógeno/genética , Enfermedades Cardiovasculares/genética , Modelos Animales de Enfermedad , Sistema Renina-Angiotensina/genética , Renina/genética , Equilibrio Hidroelectrolítico/genética , Enzima Convertidora de Angiotensina 2/deficiencia , Enzima Convertidora de Angiotensina 2/genética , Angiotensinógeno/deficiencia , Animales , Presión Sanguínea/genética , Enfermedades Cardiovasculares/metabolismo , Enfermedades Cardiovasculares/patología , Regulación de la Expresión Génica , Humanos , Riñón/citología , Riñón/metabolismo , Ratones , Ratones Noqueados , Receptor de Angiotensina Tipo 1/deficiencia , Receptor de Angiotensina Tipo 1/genética , Receptor de Angiotensina Tipo 2/deficiencia , Receptor de Angiotensina Tipo 2/genética , Renina/deficiencia , Transducción de SeñalRESUMEN
The upcoming flu season in the Northern Hemisphere merging with the current COVID-19 pandemic raises a potentially severe threat to public health. Through experimental coinfection with influenza A virus (IAV) and either pseudotyped or live SARS-CoV-2 virus, we found that IAV preinfection significantly promoted the infectivity of SARS-CoV-2 in a broad range of cell types. Remarkably, in vivo, increased SARS-CoV-2 viral load and more severe lung damage were observed in mice coinfected with IAV. Moreover, such enhancement of SARS-CoV-2 infectivity was not observed with several other respiratory viruses, likely due to a unique feature of IAV to elevate ACE2 expression. This study illustrates that IAV has a unique ability to aggravate SARS-CoV-2 infection, and thus, prevention of IAV infection is of great significance during the COVID-19 pandemic.
Asunto(s)
COVID-19/patología , Coinfección/patología , Virus de la Influenza A/fisiología , Infecciones por Orthomyxoviridae/patología , SARS-CoV-2/fisiología , Enzima Convertidora de Angiotensina 2/deficiencia , Enzima Convertidora de Angiotensina 2/genética , Enzima Convertidora de Angiotensina 2/metabolismo , Animales , COVID-19/virología , Catepsina L/genética , Catepsina L/metabolismo , Línea Celular , Coinfección/virología , Humanos , Virus de la Influenza A/aislamiento & purificación , Pulmón/patología , Ratones , Ratones Transgénicos , Infecciones por Orthomyxoviridae/virología , ARN Guía de Kinetoplastida/metabolismo , SARS-CoV-2/aislamiento & purificación , Serina Endopeptidasas/genética , Serina Endopeptidasas/metabolismo , Índice de Severidad de la Enfermedad , Carga Viral , Internalización del VirusRESUMEN
As the multi-systemic components of COVID-19 emerge, parallel etiologies can be drawn between SARS-CoV-2 infection and radiation injuries. While some SARS-CoV-2-infected individuals present as asymptomatic, others exhibit mild symptoms that may include fever, cough, chills, and unusual symptoms like loss of taste and smell and reddening in the extremities (e.g., "COVID toes," suggestive of microvessel damage). Still others alarm healthcare providers with extreme and rapid onset of high-risk indicators of mortality that include acute respiratory distress syndrome (ARDS), multi-organ hypercoagulation, hypoxia and cardiovascular damage. Researchers are quickly refocusing their science to address this enigmatic virus that seems to unveil itself in new ways without discrimination. As investigators begin to identify early markers of disease, identification of common threads with other pathologies may provide some clues. Interestingly, years of research in the field of radiation biology documents the complex multiorgan nature of another disease state that occurs after exposure to high doses of radiation: the acute radiation syndrome (ARS). Inflammation is a key common player in COVID-19 and ARS, and drives the multi-system damage that dramatically alters biological homeostasis. Both conditions initiate a cytokine storm, with similar pro-inflammatory molecules increased and other anti-inflammatory molecules decreased. These changes manifest in a variety of ways, with a demonstrably higher health impact in patients having underlying medical conditions. The potentially dramatic human impact of ARS has guided the science that has identified many biomarkers of radiation exposure, established medical management strategies for ARS, and led to the development of medical countermeasures for use in the event of a radiation public health emergency. These efforts can now be leveraged to help elucidate mechanisms of action of COVID-19 injuries. Furthermore, this intersection between COVID-19 and ARS may point to approaches that could accelerate the discovery of treatments for both.
Asunto(s)
COVID-19/fisiopatología , Pandemias , Traumatismos por Radiación/fisiopatología , SARS-CoV-2/patogenicidad , Lesión Pulmonar Aguda/etiología , Lesión Pulmonar Aguda/fisiopatología , Enzima Convertidora de Angiotensina 2/deficiencia , Enzima Convertidora de Angiotensina 2/fisiología , Animales , Antibacterianos/uso terapéutico , Antiinflamatorios/uso terapéutico , Antioxidantes/uso terapéutico , Biomarcadores/sangre , Trastornos de la Coagulación Sanguínea/sangre , Trastornos de la Coagulación Sanguínea/etiología , Trastornos de la Coagulación Sanguínea/fisiopatología , COVID-19/epidemiología , COVID-19/inmunología , Ensayos Clínicos como Asunto , Síndrome de Liberación de Citoquinas/sangre , Síndrome de Liberación de Citoquinas/etiología , Síndrome de Liberación de Citoquinas/fisiopatología , Enfermedades Hematológicas/etiología , Enfermedades Hematológicas/fisiopatología , Humanos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Inflamación/etiología , Inflamación/fisiopatología , Péptidos y Proteínas de Señalización Intercelular/uso terapéutico , Trasplante de Células Madre Mesenquimatosas , Ratones , Especificidad de Órganos , Piroptosis , Traumatismos por Radiación/sangre , Traumatismos por Radiación/tratamiento farmacológico , Traumatismos por Radiación/inmunología , Receptores Virales/fisiología , Sistema Renina-Angiotensina/efectos de los fármacos , Sistema Renina-Angiotensina/fisiología , SARS-CoV-2/aislamiento & purificación , Enfermedades Vasculares/tratamiento farmacológico , Enfermedades Vasculares/etiología , Enfermedades Vasculares/fisiopatología , Tratamiento Farmacológico de COVID-19RESUMEN
BACKGROUND: The whole world was hit hard by the coronavirus disease-19 (COVID-19). Given that angiotensin I converting enzyme 2 (ACE2) is the viral entry molecule, understanding ACE2 has become a major focus of current COVID-19 research. ACE2 is highly expressed in the gut, but its role has not been fully understood and thus COVID-19 treatments intending to downregulate ACE2 level may cause untoward side effects. Gaining insight into the functions of ACE2 in gut homeostasis therefore merits closer examination, and is beneficial to find potential therapeutic alternatives for COVID-19. METHODS: We took advantage of Ace2 knockout out mice and isolated intestinal organoids to examine the role of ACE2 in intestinal stemness. Inflammatory bowel disease (IBD) mouse model was established by 4% dextran sodium sulfate. LGR5 and KI67 levels were quantitated to reflect the virtue of intestinal stem cells (ISCs). FITC-dextran 4 (FD-4) assay was used to assess intestinal barrier function. RESULTS: Western blotting identified the expression of ACE2 in colon, which was consistent with the results of immunofluorescence and RT-PCR. Moreover, Ace2-/- organoids showed decreased LRG5 and KI67 levels, and elevated calcium concentration. Furthermore, the permeability of ace2-/- organoids was markedly increased compared with ace2+/+ organoids. Collectively, ace2-/- mice were more susceptible than ace2+/+ mice to IBD, including earlier bloody stool, undermined intestinal architecture and more pronounced weight loss. CONCLUSIONS: Our data reveal that ACE2 contributes to the proliferation of intestinal stem cells and hence orchestrates the mucosal homeostasis.
Asunto(s)
Enzima Convertidora de Angiotensina 2/metabolismo , Epitelio/metabolismo , Enzima Convertidora de Angiotensina 2/deficiencia , Animales , Calcio/metabolismo , Permeabilidad de la Membrana Celular , Enfermedades Inflamatorias del Intestino/enzimología , Enfermedades Inflamatorias del Intestino/patología , Intestinos/patología , Ratones Endogámicos C57BL , Ratones Noqueados , Organoides/metabolismo , Células Madre/citología , Células Madre/metabolismoRESUMEN
As of June 2020, the COVID-19 pandemic has totaled over 9 000 000 cases and 470 000 deaths globally (ref. 1). Emerging data from COVID-19 patients have suggested a clear role for oxidative stress in the pathogenesis of SARS-CoV-2, the pathogenic agent of COVID-19. Several comorbidities, including hypertension, diabetes, obesity, and aging, have been associated with an increase in baseline oxidative stress, likely explaining why such individuals at risk for poor outcomes with SARS-CoV-2 infection. Similarly, the concept of oxidative stress remains one of the best supported theories to explain the mechanism behind aging. Oxidative stress through both endogenous and exogenous sources has known deleterious effects in both aging and SARS-CoV-2 infection. Herein, we will review the role of oxidative stress as a key player in both aging and COVID-19 and highlight why some individuals may have better or poorer outcomes because of this. Additionally, we will discuss potential therapeutic pathways for effectively anti-aging as we take away from our learnings on COVID-19.
Asunto(s)
Envejecimiento/fisiología , COVID-19/fisiopatología , Estrés Oxidativo , Enzima Convertidora de Angiotensina 2/deficiencia , Humanos , Pronóstico , Factores de Riesgo , SARS-CoV-2RESUMEN
SARS-CoV-2, the agent of COVID-19, shares a lineage with SARS-CoV-1, and a common fatal pulmonary profile but with striking differences in presentation, clinical course, and response to treatment. In contrast to SARS-CoV-1 (SARS), COVID-19 has presented as an often bi-phasic, multi-organ pathology, with a proclivity for severe disease in the elderly and those with hypertension, diabetes and cardiovascular disease. Whilst death is usually related to respiratory collapse, autopsy reveals multi-organ pathology. Chronic pulmonary disease is underrepresented in the group with severe COVID-19. A commonality of aberrant renin angiotensin system (RAS) is suggested in the at-risk group. The identification of angiotensin-converting-enzyme 2 (ACE2) as the receptor allowing viral entry to cells precipitated our interest in the role of ACE2 in COVID-19 pathogenesis. We propose that COVID-19 is a viral multisystem disease, with dominant vascular pathology, mediated by global reduction in ACE2 function, pronounced in disease conditions with RAS bias toward angiotensin-converting-enzyme (ACE) over ACE2. It is further complicated by organ specific pathology related to loss of ACE2 expressing cells particularly affecting the endothelium, alveolus, glomerulus and cardiac microvasculature. The possible upregulation in ACE2 receptor expression may predispose individuals with aberrant RAS status to higher viral load on infection and relatively more cell loss. Relative ACE2 deficiency leads to enhanced and protracted tissue, and vessel exposure to angiotensin II, characterised by vasoconstriction, enhanced thrombosis, cell proliferation and recruitment, increased tissue permeability, and cytokine production (including IL-6) resulting in inflammation. Additionally, there is a profound loss of the "protective" angiotensin (1-7), a vasodilator with anti-inflammatory, anti-thrombotic, antiproliferative, antifibrotic, anti-arrhythmic, and antioxidant activity. Our model predicts global vascular insult related to direct endothelial cell damage, vasoconstriction and thrombosis with a disease specific cytokine profile related to angiotensin II rather than "cytokine storm". Our proposed mechanism of lung injury provides an explanation for early hypoxia without reduction in lung compliance and suggests a need for revision of treatment protocols to address vasoconstriction, thromboprophylaxis, and to minimize additional small airways and alveolar trauma via ventilation choice. Our model predicts long term sequelae of scarring/fibrosis in vessels, lungs, renal and cardiac tissue with protracted illness in at-risk individuals. It is hoped that our model stimulates review of current diagnostic and therapeutic intervention protocols, particularly with respect to early anticoagulation, vasodilatation and revision of ventilatory support choices.