Renin-Angiotensin-Aldosterone System Inhibitors in COVID-19: A Review

Among the multiple uncertainties surrounding the novel coronavirus disease (COVID-19) pandemic, a research letter published in The Lancet implicated drugs that antagonize the renin-angiotensin-aldosterone system (RAAS) in an unfavorable prognosis of COVID-19. This report prompted investigations to identify mechanisms by which blocking angiotensin-converting enzyme 2 (ACE2) could lead to serious consequences in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The possible association between RAAS inhibitors use and unfavorable prognosis in this disease may have been biased by the presence of underlying cardiovascular diseases. As the number of COVID-19 cases has increased worldwide, it has now become possible to investigate the association between RAAS inhibitors and unfavorable prognosis in larger cohorts. Observational studies and one randomized clinical trial failed to identify any consistent association between the use of these drugs and unfavorable prognosis in COVID-19. In view of the accumulated clinical evidence, several scientific societies recommend that treatment with RAAS inhibitors should not be discontinued in patients diagnosed with COVID-19 (unless contraindicated). This recommendation should be followed by clinicians and patients.

Compromiso neurológico en infección por COVID-19 en pacientes pediátricos / Neurologic compromise in pediatric COVID-19 infection

Resumen: La enfermedad por coronavirus ha extendido su compromiso más allá del sistema respiratorio con reportes crecientes de compromiso en diferentes sistemas, uno de ellos, el Sistema Nervioso. El potencial neuroinvasivo de este agente patógeno se explicaría por su neurotropismo dada la presencia de receptores de ACE2 a nivel de encéfalo y médula espinal, además del importante com promiso inflamatorio sistémico. El compromiso neurológico debido a la infección se ha dividido en Sistema Nervioso Central, destacando síntomas inespecíficos y leves como mareos y cefalea, así como cuadros graves con encefalitis y patología cerebrovascular, y Sistema Nervioso Periférico en donde la mayor relevancia guarda relación con la anosmia, ageusia y miositis. A nivel pediátrico el compromiso parece ser menor que en adultos, pero existe un reporte creciente en la literatura respecto a estos hallazgos. Es de gran importancia de contar con un adecuado registro y anamnesis que permita identificar precozmente el compromiso neurológico.

Abstract: Coronavirus disease has extended its involvement beyond the respiratory system, with increasing reports of involving different systems, such as Nervous System. The neuroinvasive potential of this pathogen would be explained by its neurotropism given the presence of ACE2 receptors in the brain and spinal cord, in addition to the important systemic inflammatory involvement. The neu rological involvement due to infection is divided between the central nervous system, highlighting non-specific and mild symptoms such as dizziness and headache, as well as severe symptoms with encephalitis and cerebrovascular pathology, and the peripheral nervous system, which mainly pre sents anosmia, ageusia, and myositis. Clinical symptomatology in pediatric patients seems to be less than in adults, but there is a growing report in the literature regarding these findings. There fore, it is very important to have an adequate registry and anamnesis that allow early identification of neurological involvement.

Manifestaciones gastrointestinales y hepáticas de COVID-19 en niños / Gastrointestinal and hepatic manifestations of COVID-19 in children

Resumen: SARS-CoV-2 es un virus de alta estabilidad ambiental. Es principalmente un patógeno respiratorio que también afecta el tracto gastrointestinal. El receptor ACE2 es el principal receptor de SARS- CoV-2, hay evidencia de su elevada presencia en intestino, colon y colangiocitos; igualmente se en cuentra expresado en hepatocitos pero en menor proporción. SARS-CoV-2 tiene un tropismo gas trointestinal que explica los síntomas digestivos y la diseminación viral en deposiciones. Las caracte rísticas de SARS-CoV-2 incluyen a la proteína S (Spike o Espícula) que se une de forma muy estable al receptor ACE2. La infección por SARS-CoV-2 produce disbiosis y alteraciones en el eje pulmón- intestino. A nivel intestinal y hepático produce una respuesta Linfocitos T evidente y una respuesta de citocinas que producirían daño intestinal inflamatorio. Las manifestaciones a nivel intestinal en orden de frecuencia son pérdida de apetito, diarrea, náuseas, vómitos y dolor abdominal. Éste último podría ser un marcador de gravedad. En niños la diarrea es habitualmente leve y autolimitada. A nivel hepático la hipertransaminasemia ocurre en 40-60% de los pacientes graves. SARS-CoV-2 puede per manecer en deposiciones un tiempo más prolongado que en secreciones respiratorias, este hallazgo influiría en la diseminación de enfermedad. En esta revisión se destaca la importancia de efectuar un reconocimiento precoz de las manifestaciones gastrointestinales y hepáticas, aumentar el índice de sospecha, efectuar un diagnóstico oportuno y reconocer eventuales complicaciones de la enferme dad. La potencial transmisión fecal oral puede influir en la diseminación de enfermedad. Reconocer este hallazgo es importante para definir aislamiento.

Abstract: SARS-CoV-2 is a high environmental stable virus. It is predominantly a respiratory pathogen that also affects the gastrointestinal tract. The ACE 2 receptor is the main receptor of SARS-CoV-2, with evidence of its high presence in the intestine, colon and cholangiocytes, and, in smaller proportion, in hepatocytes. SARS-CoV-2 has a gastrointestinal tropism that explains digestive symptoms and viral spread in stools. The characteristics of this virus include the S (Spike) protein that binds very stably to the ACE-2 receptor and, at the same time, SARS-CoV-2 produces dysbiosis and alterations in the gut-lung axis. It produces a clear T-cell response and a cytokines storm in the intestine and liver that would produce inflammatory bowel damage. Intestinal manifestations by order of frequency are loss of appetite, diarrhea, nausea and vomiting, and abdominal pain, where the latter could be a severity marker. In children, diarrhea is the most frequent symptom, usually mild and self-limiting. In the liver, hypertransaminasemia occurs in severe patients ranging from 40 to 60%. SARS-CoV-2 can re main in stools longer than in respiratory secretions, which would influence the spread of disease. This article highlights the importance of an early diagnosis of gastrointestinal and hepatic manifestations, increase the index of suspicion, make a timely diagnosis, and recognize eventual complications of the disease. The potential oral-fecal route of transmission may influence the disease spread. Recognizing this finding is important to define isolation.

Eje Renina Angiotensina, Enzima Convertidora de Angiotensina 2 y Coronavirus / Renin Angiotensin Axis, Angiotensin Converting Enzyme 2 and Coronavirus

Resumen: El sistema renina angiotensina aldosterona (SRAA) es el principal regulador del volumen plasmático, manteniendo la homeostasis cardiovascular e hidrosalina. En la vía clásica, la enzima convertidora de angiotensina (ECA) genera Angiotensina II (AngII), de potente efecto inflamatorio y vasoconstrictor. Esta vía clásica es a su vez regulada por la ECA2, que convierte AngII a Ang 1-7, cuyas acciones vaso dilatadoras y antiinflamatorias dan balance a los efectos de AngII. La ECA2 se ha relacionado con la patogenia de infecciones respiratorias como el virus respiratorio sincicial y el síndrome respiratorio agudo grave por coronavirus (SARS-CoV y SARS-CoV-2). Estudios recientes han demostrado que la ECA2 corresponde al principal receptor del SARS-CoV-2, que en conjunto con otros receptores como la serin proteasa TMPRSS2, permiten la fijación, fusión y entrada del virus a la célula huésped. En animales infectados por SARS-CoV se produce una caída de la concentración tisular de ECA2 y Ang 1-7, con la consiguiente sobreexpresión de AngII, y sus efectos vasoconstrictores e inflamatorios. Experimentos con ECA2 recombinante han mostrado un efecto protector frente a la sobreexpresión del SRAA en animales infectados por SARS-CoV, efecto similar al demostrado con el uso de bloquea- dores del receptor de AngII, AT1. La evidencia sobre el rol protector de ECA2 parece respaldar las recomendaciones respecto a no suspender estos medicamentos en la infección SARS-CoV-2. En este artículo presentamos el conocimiento actual sobre el rol del SRAA en la infección por SARS-CoV, a partir de conceptos fisiopatológicos, bases moleculares, y evidencia experimental y clínica.

Abstract: The renin-angiotensin-aldosterone system (RAAS) is the main plasma volume regulator, which maintains cardiovascular and hydrosaline homeostasis. In the classical pathway, the angiotensin converting enzyme (ACE) generates Angiotensin II (AngII), which is powerfully inflammatory and vasoconstrictive. This classical pathway is also regulated by ACE2, which converts AngI to Ang 1-9, and degrades AngII to Ang 1-7, whose vasodilatory and anti-inflammatory functions balance out the effects of AngII. ACE2 has been associated with the pathogenesis of respiratory infections such as RSV and severe acute respiratory syndrome coronavirus (SARS-CoV and SARS-CoV-2). Recent studies have shown that ACE2 corresponds to the main SARS-CoV-2 receptor, which together with other receptors such as the TMPRSS2, allows the virus to attach, fuse, and enter the host cell. These studies have shown that in animals infected with coronavirus there is a drop in tissue concentration of ACE2 and Ang 1-7, leading to overexpression of AngII and its vasoconstrictive and inflammatory effects. Experiments with recombinant ACE2 have shown a protective effect against overexpression of RAAS in coronavirus-infected animals, which is similar to that demonstrated with the use of AnglI receptor blockers (AT1). Evidence on the protective role of ACE2 seems to support the recommendations re garding not discontinuing these drugs in COVID-19 infection. In this article, we present the current knowledge about the role of RAAS in coronavirus infection, based on physiopathological concepts, molecular bases, and experimental and clinical evidence.

O Efeito da Doença de Coronavírus 2019 nas Doenças Cardiovasculares / The Effect of Coronavirus Disease 2019 on Cardiovascular Diseases

Resumo A doença de coronavírus 2019 (COVID-19) é uma pandemia global afetando o mundo, estando presente em mais de 1.300.000 pacientes. O COVID-19 age pelo receptor da enzima conversora de angiotensina 2 (ECA2). As comorbidades cardiovasculares são mais frequentes com COVID-19, e cerca 10% de casos desenvolvem miocardite (22% de pacientes críticas). Mais pesquisas serão necessárias para continuar ou descontinuar inibidores de ECA e bloqueadores dos receptores da angiotensina, que são essenciais para hipertensão e insuficiência cardíaca em COVID-19. Pesquisa intensiva é promissora para o tratamento e a prevenção da COVID-19.

Abstract Coronavirus disease 2019 (COVID-19) is a global pandemic affecting the world, seen in more than 1,300,000 patients. COVID-19 acts through the angiotensin-converting enzyme 2 (ACE2) receptor. Cardiovascular comorbidities are more common with COVID-19, and nearly 10% of cases develop myocarditis (22% of critical patients). Further research is needed to continue or discontinue ACE inhibitors and angiotensin receptor blockers, which are essential in hypertension and heart failure in COVID-19. Intensive research is promising for the treatment and prevention of COVID-19.

Antihipertensivos en pacientes con COVID-19 / Anti hypertensive agents in patients with COVID-19

En 31 de diciembre del 2019 la Organización Mundial de la Salud fue informada por las autoridades sanitarias chinas de la aparición de casos de neumonía de origen desconocido en la ciudad de Wuhan en China. El 7 de Enero de 2020, científicos chinos identificaron a un nuevo coronavirus (temporalmente designado como "2019-nCoV") como el agente etiológico de la enfermedad denominada COVID-19. La secuenciación del genoma del nuevo coronavirus mostró gran similitud con el coronavirus (Covid-1 o SARS-CoV) causante del síndrome respiratorio agudo severo (SARS), ocurrido también en China entre los años 2002-2003. Por este motivo, 2019-nCoV se rebautizó como SARS-CoV-2 (Severe Acute Respiratory Syndrome Corona Virus-2) y a la fecha es responsable de la actual y grave pandemia que está ocasionando impactos sanitarios y socio-económicos a escala global. Las investigaciones con SARS-CoV establecieron que este virus ingresa a nuestras células utilizando como receptor a la enzima convertidora de angiotensina tipo 2 (ECA 2 o en inglés ACE-2: "angiotensin converting enzyme type 2"). Dado este antecedente también se confirmó que SARS-CoV-2 también utiliza esta misma enzima ya que no se habla de un mecanismo en si para ingresar a sus células blanco, especialmente a nivel de nuestro sistema respiratorio. ECA-2 es una proteasa integrante del sistema renina angiotensina "alterno o no canónico" con importantes acciones regulatorias sobre los sistemas cardiovascular, renal y pulmonar, entre otros. En este contexto, ha surgido preocupación tanto por clínicos como los propios pacientes respecto al estado de pacientes hipertensos con COVID-19 y su vulnerabilidad a infectarse con SARS-CoV-2 dado que algunos trabajos han planteado que ciertos polimorfismos en el gen ECA-2 asociados a hipertensión arterial podrían determinar una mayor expresión de ECA-2. Además, estudios preclínicos han sugerido que ciertos fármacos antihipertensivos (principalmente, inhibidores de ECA y antagonistas del receptor para angiotensina II subtipo 1) también podrían estimular una mayor expresión de ECA-2. Esta revisión tiene por objetivo presentar y discutir los antecedentes en el estado del arte respecto a esta reciente problemática. El análisis crítico de los presentes antecedentes permite concluir que no existe evidencia clínica sólida que permita afirmar que el uso de medicamentos antihipertensivos genere una mayor vulnerabilidad a la infección con SARS-CoV-2. Por lo tanto no se debe descontinuar su uso en pacientes hipertensos en riesgo de infección a SARS-CoV-2 o que padezcan COVID-19.

In December 2019, a new type of coronavirus emerged in the city of Wuhan, China. This novel virus has unleashed a pandemic that has inflicted a considerable impact on public health and the economy and has therefore become a severe concern worldwide. This new virus -named SARS-CoV-2has been rapidly investigated in order to create knowledge aimed at achieving its control. Comparative studies with SARS-CoV virus, responsible for the 2002-2003 pandemic, suggest that SARS-CoV-2 requires the same receptor to bind and infect cells: angiotensin converting enzyme 2 (ACE-2). This hypothesis has been thoroughly supported by a variety of in vitro research and is currently considered a potential therapeutic target. ACE-2 is part of the counter-regulatory renin-angiotensin system, exerting effects in pulmonary, renal and cardiovascular systems. In this context, concerns have arisen in regards to the vulnerability of hypertensive patients against COVID-19, given that there is evidence that may suggest that polymorphisms associated to hypertension may increase the expression of ACE-2. Moreover, preclinical studies have shown that antihypertensive drugs may increase the expression of this enzyme. In this review article, we present the current state of the art on this polemic topic. Our critical analysis suggest that there is no robust clinical evidence supporting the hypothesis that the use of antihypertensive drugs can increase vulnerability to infection with SARS-CoV-2. Therefore, we recommend that the use of these therapeutic agents should not be discontinued in hypertensive patients in risk to or suffering COVID-19.

Sars-CoV-2: A clinical update - II

SUMMARY INTRODUCTION A covid-19 pandemic decreed by WHO has raised greater awareness of it. EPIDEMIOLOGY The infection, reached the mark of 2,000,000 patients in 33 countries and caused the risk of the presence of comorbidities and advanced age. TRANSMISSIBILITY The transmissibility calculated so far is similar to the H1N1 epidemic, but with lower mortality rates. PHYSIOPATHOLOGY The SARS-CoV-2 virus, of the Coronaviridae family, has the capacity for cellular invasion through the angiotensin-converting enzyme 2 does not have a lower respiratory epithelium and in the cells of the small intestine mucosa. CLINICAL MANIFESTATIONS a presentation can be divided into mild (fever, fatigue, cough, myalgia, and sputum) and severe (cyanosis, dyspnoea, tachypnea, chest pain, hypoxemia and need for clinical measurement) and has an estimated estimate of 2%. DIAGNOSIS allows the detection of viral load in CRP-TR of patients with high clinical suspicion. TREATMENT based on supportive measures and infection control. In severe cases, the use of medications such as hydroxychloroquine and azithromycin or medication can be promising. Take care to avoid the use of corticosteroids. There are no restrictions on the use of resources and IECAs / BRAs.

RESUMO INTRODUÇÃO A pandemia de Covid-19 decretada pela OMS suscita maior conhecimento acerca da doença. EPIDEMIOLOGIA A infecção atingiu a marca de 2 milhões de pacientes em 33 países e levantou como fatores de risco a presença de comorbidades e a idade avançada. TRANSMISSIBILIDADE A transmissibilidade calculada até o momento é similar à da epidemia de H1N1, contudo, com taxa de mortalidade inferior. FISIOPATOLOGIA O vírus Sars-CoV-2, da família Coronaviridae, tem capacidade de invasão celular através da enzima conversora de angiotensina 2 presente no epitélio respiratório inferior e nas células da mucosa do intestino delgado. MANIFESTAÇÕES CLÍNICAS A apresentação pode ser dividida em leve (febre, fadiga, tosse, mialgia e escarro) e grave (cianose, dispneia, taquipneia, dor torácica, hipoxemia e necessidade de ventilação mecânica) e tem mortalidade estimada de pouco mais de 2%. DIAGNÓSTICO Dá-se pela detecção da carga viral no PCR-TR de pacientes com alta suspeição clínica. TRATAMENTO Baseado em medidas de suporte e de controle de infecção. Em casos graves, uso de medicamentos como hidroxicloroquina e azitromicina ou remdesevir pode ser promissor. Deve-se evitar o uso de corticosteroides. Não há evidências suficientes para abster-se do uso de ibuprofeno e IECAs/BRAs.

Implicaciones cardiovasculares de la infección por SARS-CoV-2: revisión de literatura / Cardiovascular implications of SARS-CoV-2 infection: a literature review

En diciembre de 2019 se reportó en Wuhan, China, la aparición de una nueva cepa de coronavirus SARS-CoV-2 que producía un compromiso pulmonar severo y progresaba a estrés respiratorio agudo. A la fecha, son más de diecisiete millones los casos confirmados y más de medio millón los fallecidos en todo el mundo a causa de COVID-19. Los estudios reportan que los pacientes con enfermedad cardiovascular son más susceptibles a contraer esta enfermedad y a presentar más complicaciones. El propósito de esta revisión es proporcionar información actualizada para los profesionales de la salud que atienden a pacientes con COVID-19 y que tienen además enfermedad cardiovascular y por ende un riesgo elevado de complicaciones y mortalidad. Realizamos una búsqueda de bibliografía científica acerca de la asociación de enfermedad cardiovascular y COVID-19 en diferentes bases de datos como Scopus, MEDLINE vía PubMed y Cochrane Library. El tratamiento con inhibidores de la enzima convertidora de angiotensina y bloqueadores del receptor de angiotensina ha sido motivo de discusión y no hay evidencia sólida para contraindicarlo en pacientes con COVID-19. Respecto al tratamiento con hidroxicloroquina asociado o no con azitromicina, hay evidencia que demuestra un mayor riesgo con su utilización, que beneficio clínico y/o disminución de mortalidad. En este contexto, los pacientes con insuficiencia cardíaca representan un grupo importante de riesgo por su condición per se y por el dilema diagnóstico generado al evaluar un paciente con COVID-19, en el que los signos de insuficiencia cardíaca aguda podrían enmascararse. Por otro lado, en los pacientes con síndrome coronario agudo, el enfoque terapéutico inicial podría cambiar en el contexto de la pandemia, aunque sólo sobre la base de opiniones de expertos. Quedan, sin embargo, muchos temas en controversia que serán motivo de investigaciones futuras.

In December 2019, a new strain of the SARS-CoV-2 coronavirus was reported in Wuhan, China, which produced severe lung involvement and progressed to respiratory distress. To date, more than seventeen million confirmed cases and more than half a million died worldwide from COVID-19. Patients with cardiovascular disease are more susceptible to contracting this disease and presenting more complications. We did a literature search on the association of cardiovascular disease and COVID-19 in databases such as Scopus, PubMed/MEDLINE, and the Cochrane Library. The purpose of this review is to provide updated information for health professionals who care for patients with COVID-19 and cardiovascular disease, given that they have a high risk of complications and mortality. Treatment with angiotensin-converting enzyme inhibitors and receptor blockers is controversial, and there is no evidence not to use these medications in patients with COVID-19. Regarding treatment with hydroxychloroquine associated or not with azithromycin, there is evidence of a higher risk with its use than clinical benefit and decreased mortality. Likewise, patients with heart failure are an important risk group due to their condition per se. Patients with heart failure and COVID-19 are a diagnostic dilemma because the signs of acute heart failure could be masked. On the other hand, in patients with acute coronary syndrome, the initial therapeutic approach could change in the context of the pandemic, although only based on expert opinions. Nonetheless, many controversial issues will be the subject of future research.

Susceptibility of the elderly to SARS-COV-2 infection: ace-2 overexpression, shedding, and antibody-dependent enhancement (ADE)

The world is currently facing a serious SARS-CoV-2 infection pandemic. </mac_aq>This virus is a new isolate of coronavirus, and the current infection crisis has surpassed the SARS and MERS epidemics</mac_aq> that occurred in 2002 and 2013, respectively. SARS-CoV-2 has currently infected more than 142,000 people, causing </mac_aq>5,000 deaths and spreading across more than 130 </mac_aq>countries worldwide. The spreading capacity of the virus clearly demonstrates the potential threat </mac_aq>of respiratory viruses to human health, thereby reiterating to the governments around the world that preventive </mac_aq>health policies and scientific research are pivotal to overcoming the crisis. Coronavirus disease (COVID-19) causes flu-like symptoms in most cases. However, approximately 15% of the patients need hospitalization, and 5% require assisted ventilation, depending on the cohorts studied. What is intriguing, however, is the higher susceptibility of the elderly, especially individuals who are older than 60 years of age, and have comorbidities, including hypertension, diabetes, and heart disease. In fact, the death rate in this group may be up to 10-12%. Interestingly, children are somehow less susceptible and are not considered as a risk group. Therefore, in this review, we discuss some possible molecular and cellular mechanisms by virtue of which the elderly subjects may be more susceptible to severe COVID-19. Toward this, we raise two main </mac_aq>points, i) increased ACE-2 expression in pulmonary and heart tissues in users of chronic angiotensin 1 </mac_aq>receptor (AT1R) blockers; and ii) antibody-dependent enhancement (ADE) after previous exposure to other circulating coronaviruses. We believe that these points are pivotal for a better understanding of the pathogenesis of severe COVID-19, and must be carefully addressed by physicians and scientists in the field.

COVID-19 y el sistema renina, angiotensina, aldosterona. Una relación compleja / COVID-19 and the renin, angiotensin, aldosterone system. A complex relationship

Resumen La pandemia por COVID-19 ha tenido muy importantes repercusiones negativas, sanitarias, psicológicas, sociales y económicas para las personas, las familias, las comunidades, los países y para las para la humanidad en general. La interrelación con la edad y la presencia de enfermedades crónicas no trasmisibles (hipertensión, diabetes, obesidad, tabaquismo) parece ir mas lejos que lo que explicaría la prevalencia y distribución de ambas. Los medicamentos que actúan sobre el sistema renina-angiotensina-aldosterona, son pilares básicos en el manejo de estas enfermedades. Se sabe de tiempo atrás que estos fármacos aumentan en forma significativa la expresión en el tejido pulmonar de receptores para la enzima de conversión de angiotensina de tipo 2. Este hecho junto con el conocimiento de que la vía de entrada del virus a la célula es precisamente el receptor de ECA-2, inició una hipótesis, basada en evidencia de muy baja calidad, que rápidamente se generalizó en los medios de comunicación, de que el empleo de estos medicamentos podría ser negativo y que deberían suspenderse. La respuesta de prácticamente todas las sociedades científicas fue casi inmediata, con la indicación precisa de que no debería suspenderse el tratamiento con estos fármacos, puesto que la evidencia de su utilidad está basada en una evidencia muy sólida y de gran calidad. Casi simultáneamente también apareció la hipótesis, también basada en evidencia muy preliminar, de que estos medicamentos no solo resultan dañinos sino que son benéficos, tampoco se aceptan todavía como agentes para la prevención o tratamiento de esta enfermedad o sus complicaciones. La presente revisión relata los conocimientos actuales sobre la relación entre COVID-19 y SRAA.

Abstract The COVID-19 pandemic has had major negative health, psychological, social and economic repercussions for individuals, families, communities, countries and for humanity in general. The interrelation with age and the presence of chronic non-communicable diseases (hypertension, diabetes, obesity, smoking) seems to go further than what would be explained by the prevalence and distribution of both. The drugs that act on the renin-angiotensin-aldosterone system are in many cases the backbone for the management of these diseases, it has been known for a long time that these drugs significantly increase the expression of receptors for angiotensin conversion enzyme type 2 in the lung tissue. This fact, together with the knowledge that the route of entry of the virus into the cell is precisely the ACE-2 receptor, initiated a hypothesis, based on very low-quality evidence, which quickly became generalized in the media, that the use of these drugs could be negative and that they should be interrupted immediately. The response of practically all Scientific Societies was almost immediate, with the precise indication that treatment with these drugs should not be discontinued, since the evidence of their usefulness is based on very solid and high-quality evidence. Simultaneously, a different hypothesis also appeared, also based on very preliminary evidence, that these drugs are not only harmful but also beneficial, however these medicaments are not yet accepted as agents for the prevention or treatment of this disease or its complications. This review reports current knowledge on the relationship between COVID-19 and SRAA.

Activation of endogenous angiotensin converting enzyme 2 prevents early injuries induced by hyperglycemia in rat retina

Diabetic retinopathy (DR) is a serious complication of diabetes mellitus that may result in blindness. We evaluated the effects of activation of endogenous angiotensin converting enzyme (ACE) 2 on the early stages of DR. Rats were administered an intravenous injection of streptozotocin to induce hyperglycemia. The ACE2 activator 1-[[2-(dimethylamino) ethyl] amino]-4-(hydroxymethyl)-7-[[(4-methylphenyl) sulfonyl] oxy]-9H-xanthone 9 (XNT) was administered by daily gavage. The death of retinal ganglion cells (RGC) was evaluated in histological sections, and retinal ACE2, caspase-3, and vascular endothelial growth factor (VEGF) expressions were analyzed by immunohistochemistry. XNT treatment increased ACE2 expression in retinas of hyperglycemic (HG) rats (control: 13.81±2.71 area%; HG: 14.29±4.30 area%; HG+XNT: 26.87±1.86 area%; P<0.05). Importantly, ACE2 activation significantly increased the RCG number in comparison with HG animals (control: 553.5±14.29; HG: 530.8±10.3 cells; HG+XNT: 575.3±16.5 cells; P<0.05). This effect was accompanied by a reduction in the expression of caspase-3 in RGC of the HG+XNT group when compared with untreated HG rats (control: 18.74±1.59; HG: 38.39±3.39 area%; HG+XNT: 27.83±2.80 area%; P<0.05). Treatment with XNT did not alter the VEGF expression in HG animals (P>0.05). Altogether, these findings indicate that activation of ACE2 reduced the death of retinal ganglion cells by apoptosis in HG rats.

Mechanisms of the antihypertensive effects of Nigella sativa oil in L-NAME-induced hypertensive rats

OBJECTIVES: This study was conducted to determine whether the blood pressure-lowering effect of Nigella sativa might be mediated by its effects on nitric oxide, angiotensin-converting enzyme, heme oxygenase and oxidative stress markers. METHODS: Twenty-four adult male Sprague-Dawley rats were divided equally into 4 groups. One group served as the control (group 1), whereas the other three groups (groups 2-4) were administered L-NAME (25 mg/kg, intraperitoneally). Groups 3 and 4 were given oral nicardipine daily at a dose of 3 mg/kg and Nigella sativa oil at a dose of 2.5 mg/kg for 8 weeks, respectively, concomitantly with L-NAME administration. RESULTS: Nigella sativa oil prevented the increase in systolic blood pressure in the L-NAME-treated rats. The blood pressure reduction was associated with a reduction in cardiac lipid peroxidation product, NADPH oxidase, angiotensin-converting enzyme activity and plasma nitric oxide, as well as with an increase in heme oxygenase-1 activity in the heart. The effects of Nigella sativa on blood pressure, lipid peroxidation product, nicotinamide adenine dinucleotide phosphate oxidase and angiotensin-converting enzyme were similar to those of nicardipine. In contrast, L-NAME had opposite effects on lipid peroxidation, angiotensin-converting enzyme and NO. CONCLUSION: The antihypertensive effect of Nigella sativa oil appears to be mediated by a reduction in cardiac oxidative stress and angiotensin-converting enzyme activity, an increase in cardiac heme oxygenase-1 activity and a prevention of plasma nitric oxide loss. Thus, Nigella sativa oil might be beneficial for controlling hypertension.

Target-directed catalytic metallodrugs

Most drugs function by binding reversibly to specific biological targets, and therapeutic effects generally require saturation of these targets. One means of decreasing required drug concentrations is incorporation of reactive metal centers that elicit irreversible modification of targets. A common approach has been the design of artificial proteases/nucleases containing metal centers capable of hydrolyzing targeted proteins or nucleic acids. However, these hydrolytic catalysts typically provide relatively low rate constants for target inactivation. Recently, various catalysts were synthesized that use oxidative mechanisms to selectively cleave/inactivate therapeutic targets, including HIV RRE RNA or angiotensin converting enzyme (ACE). These oxidative mechanisms, which typically involve reactive oxygen species (ROS), provide access to comparatively high rate constants for target inactivation. Target-binding affinity, co-reactant selectivity, reduction potential, coordination unsaturation, ROS products (metal-associated vs metal-dissociated; hydroxyl vs superoxide), and multiple-turnover redox chemistry were studied for each catalyst, and these parameters were related to the efficiency, selectivity, and mechanism(s) of inactivation/cleavage of the corresponding target for each catalyst. Important factors for future oxidative catalyst development are 1) positioning of catalyst reduction potential and redox reactivity to match the physiological environment of use, 2) maintenance of catalyst stability by use of chelates with either high denticity or other means of stabilization, such as the square planar geometric stabilization of Ni- and Cu-ATCUN complexes, 3) optimal rate of inactivation of targets relative to the rate of generation of diffusible ROS, 4) targeting and linker domains that afford better control of catalyst orientation, and 5) general bio-availability and drug delivery requirements.

Inhibición de la Enzima Convertidora de Angiotensina I con hidrolizados proteicos de Jatropha curcas / Angiotensin I-Converting Enzyme inhibition with protein hydrolysates from Jatropha curcas / Inibição da Enzima Conversora de Angiotensina I com hidrolisados proteicos de Jatropha curcas

Se evaluó la actividad inhibitoria in vitro de los hidrolizados proteínicos obtenidos a partir de la harina desgrasada y del aislado proteínico provenientes del grano de Jatropha curcas L. sobre la actividad de la enzima convertidora de angiotensina I (ECA-1), con la finalidad de emplearlos en un futuro para la formulación de alimentos funcionales. Los hidrolizados fueron obtenidos empleando alcalasa y el sistema enzimático pepsina-pancreatina. Se calculó la concentración media inhibitoria (IC50) para medir el grado de inhibición de la actividad enzimática de ECA-1. Fueron seleccionados los hidrolizados con el menor tiempo de hidrólisis (60 min) para evaluar la bioactividad, dado que las cinéticas de hidrólisis enzimática de la harina desgrasada y del aislado proteínico no encontraron diferencias significativas en el grado de hidrólisis para los tiempos de reacción en cada sistema (60, 90 y 120 min). Los valores de IC50 que presentaron el mejor efecto de inhibición sobre la ECA-I fueron 2,8 y 7,0 µg/mL, obtenidos a partir del aislado proteínico con la enzima alcalasa y con el sistema secuencial pepsina-pancreatina, respectivamente. Los hidrolizados de J. curcas podrían ser incorporados en la elaboración de alimentos funcionales y ser aplicados en tratamientos para personas con hipertensión por su efecto inhibitorio sobre la ECA-I.

In vitro angiotensin I-converting enzyme (ACE) inhibitory activity was evaluated in protein hydrolysates from defatted meal and protein isolate from Jatropha curcas L. Seed, in order to determine their potential inclusion in functional food formulation. Hydrolysates were produced using Alcalase® or a sequential pepsin-pancreatin enzymatic system. Mean inhibitory concentration (IC50) was used to measure the degree of ACE enzymatic activity inhibition. Bioactivity was evaluated in the hydrolysates with the lowest hydrolysis time (60 min) given that no differences in degree of hydrolysis in terms of reaction time in each system were observed (60, 90 and 120 min) in the enzymatic hydrolysis kinetics for the defatted meal and protein isolate. The protein isolate exhibited the highest inhibitory effect, as seen in the IC50 values: 2.8 µg/mL in the alcalase system and 7.0 µg/mL in the pepsin-pancreatin system. Hydrolysates from J. curcas seed exhibit ACE inhibition and could be incorporated into functional foods or treatments for those suffering hypertension.

Foi avaliada a atividade inibitória in vitro dos hidrolisados proteicos obtidos a partir da farinha desengordurada e do isolado proteico provenientes do grão de Jatropha curcas L. sobre a atividade da enzima conversora de angiotensina I (ECA-1), com o objetivo de utilizá-los num futuro para a formulação de alimentos funcionais. Os hidrolisados foram obtidos usando alcalase e o sistema enzimático pepsina-pancreatina. Foi calculada a concentração média inibitória (IC50) para medir o grau de inibição da atividade enzimática da ECA-1. Foram selecionados os hidrolisados com o menor tempo de hidrólise (60 min.) para avaliar a bioatividade visto que as cinéticas de hidrólise enzimática da farinha desengordurada e do isolado proteico não encontraram diferenças significativas no grau de hidrólise para os tempos de reação para cada sistema (60, 90 e 120 min.). Os valores de IC50 que apresentaram o melhor efeito de inibição sobre a ECA-I foram 2.8 e 7.0 µg/mL obtidos a partir do isolado proteico com a enzima alcalase e com o sistema sequencial pepsina-pancreatina respectivamente. Os hidrolisados de J. curcas poderiam ser incorporados na elaboração de alimentos funcionais e ser aplicados em tratamentos para pessoas com hipertensão por seu efeito inibitório sobre a ECA-I.

Absence of arteriosclerosis in intramyocardial coronary arteries: a mystery to be solved? / Ausência de arteriosclerose na porção intramiocárdica das artérias coronárias: um mistério a ser resolvido?

Several studies show that portions of intramyocardial coronary arteries are spared of arteriosclerosis, involving morphological, embryological, biochemical and pathophysiological aspects. Endothelial function is significantly affected in the segment of transition, as estimated by the vasoactive response to Ach. These findings suggest that myocardial bridge can provide protection against arteriosclerosis by counteracting the negative effects of endothelial dysfunction. The intramyocardial portion's protection phenomenon deserves further scientific research on all research fronts. Improved morphological, biomechanical and especially physiological and embryological knowledge may be the key to a future window of opportunity for chronic arterial disease therapy and prevention. In addition, this review discusses possible therapeutic approaches for symptomatic coronary ischemia caused by myocardial bridges.

Diversos estudos demonstram que as porções intramiocárdicas das artérias coronárias são poupadas da arteriosclerose, envolvendo aspectos morfológicos, embriológicos, biomecânicos e aspectos fisiopatológicos. A função endotelial é significativamente afetada no segmento de transição, tal como estimado pela resposta vasoativa para acetilcolina (Ach). Esses achados sugerem que ponte miocárdica pode fornecer proteção contra a arteriosclerose, por contrariar os efeitos negativos da disfunção endotelial. O fenômeno dessa proteção da porção intramiocárdica merece maior investigação científica em todas as frentes de pesquisa. Maiores conhecimentos sobre os aspectos morfológicos, biomecânicos e, principalmente, fisiológicos e embriológicos podem ser a chave para uma futura janela de oportunidades de terapia e prevenção da doença arterial crônica. Nessa revisão, discutem-se, também, possíveis abordagens terapêuticas para fenômenos coronarianos isquêmicos causados por pontes miocárdicas.

Hypertensive effects of the iv administration of picomoles of ouabain

Ouabain, an endogenous digitalis compound, has been detected in nanomolar concentrations in the plasma of several mammals and is associated with the development of hypertension. In addition, plasma ouabain is increased in several hypertension models, and the acute or chronic administration of ouabain increases blood pressure in rodents. These results suggest a possible association between ouabain and the genesis or development and maintenance of arterial hypertension. One explanation for this association is that ouabain binds to the α-subunit of the Na+ pump, inhibiting its activity. Inhibition of this pump increases intracellular Na+, which reduces the activity of the sarcolemmal Na+/Ca2+ exchanger and thereby reduces Ca2+ extrusion. Consequently, intracellular Ca2+ increases and is taken up by the sarcoplasmic reticulum, which, upon activation, releases more calcium and increases the vascular smooth muscle tone. In fact, acute treatment with ouabain enhances the vascular reactivity to vasopressor agents, increases the release of norepinephrine from the perivascular adrenergic nerve endings and promotes increases in the activity of endothelial angiotensin-converting enzyme and the local synthesis of angiotensin II in the tail vascular bed. Additionally, the hypertension induced by ouabain has been associated with central mechanisms that increase sympathetic tone, subsequent to the activation of the cerebral renin-angiotensin system. Thus, the association with peripheral mechanisms and central mechanisms, mainly involving the renin-angiotensin system, may contribute to the acute effects of ouabain-induced elevation of arterial blood pressure.

Characterization of angiotensin-converting enzymes 1 and 2 in the soleus and plantaris muscles of rats

Angiotensin-converting enzymes 1 (ACE1) and 2 (ACE2) are key enzymes of the renin-angiotensin system, which act antagonistically to regulate the levels of angiotensin II (Ang II) and Ang-(1-7). Considerable data show that ACE1 acts on normal skeletal muscle functions and architecture. However, little is known about ACE1 levels in muscles with different fiber compositions. Furthermore, ACE2 levels in skeletal muscle are not known. Therefore, the purpose of this study was to characterize protein expression and ACE1 and ACE2 activities in the soleus and plantaris muscles. Eight-week-old female Wistar rats (N = 8) were killed by decapitation and the muscle tissues harvested for biochemical and molecular analyses. ACE1 and ACE2 activities were investigated by a fluorometric method using Abz-FRK(Dnp)P-OH and Mca-YVADAPK(Dnp)-OH fluorogenic substrates, respectively. ACE1 and ACE2 protein expression was analyzed by Western blot. ACE2 was expressed in the skeletal muscle of rats. There was no difference between the soleus (type I) and plantaris (type II) muscles in terms of ACE2 activity (17.35 ± 1.7 vs 15.09 ± 0.8 uF·min-1·mg-1, respectively) and protein expression. ACE1 activity was higher in the plantaris muscle than in the soleus (71.5 ± 3.9 vs 57.9 ± 1.1 uF·min-1·mg-1, respectively). Moreover, a comparative dose-response curve of protein expression was established in the soleus and plantaris muscles, which indicated higher ACE1 levels in the plantaris muscle. The present findings showed similar ACE2 levels in the soleus and plantaris muscles that might result in a similar Ang II response; however, lower ACE1 levels could attenuate Ang II production and reduce bradykinin degradation in the soleus muscle compared to the plantaris. These effects should enhance the aerobic capacity necessary for oxidative muscle activity.

The use of Fluorescence Resonance Energy Transfer (FRET) peptidesfor measurement of clinically important proteolytic enzymes

Proteolytic enzymes have a fundamental role in many biological processes and are associated with multiple pathological conditions. Therefore, targeting these enzymes may be important for a better understanding of their function and development of therapeutic inhibitors. Fluorescence Resonance Energy Transfer (FRET) peptides are convenient tools for the study of peptidases specificity as they allow monitoring of the reaction on a continuous basis, providing a rapid method for the determination of enzymatic activity. Hydrolysis of a peptide bond between the donor/acceptor pair generates fluorescence that permits the measurement of the activity of nanomolar concentrations of the enzyme. The assays can be performed directly in a cuvette of the fluorimeter or adapted for determinations in a 96-well fluorescence plate reader. The synthesis of FRET peptides containing ortho-aminobenzoic acid (Abz) as fluorescent group and 2, 4-dinitrophenyl (Dnp) or N-(2, 4-dinitrophenyl)ethylenediamine (EDDnp) as quencher was optimized by our group and became an important line of research at the Department of Biophysics of the Federal University of São Paulo. Recently, Abz/Dnp FRET peptide libraries were developed allowing high-throughput screening of peptidases substrate specificity. This review presents the consolidation of our research activities undertaken between 1993 and 2008 on the synthesis of peptides and study of peptidases specificities.

As enzimas proteolíticas têm um papel fundamental em muitos processos biológicos e estão associadas a vários estados patológicos. Por isso, o estudo da especificidade das peptidases pode ser importante para uma melhor compreensão da função destas enzimas e para o desenvolvimento de inibidores. Os substratos com supressão intramolecular de fluorescência constituem uma excelente ferramenta, pois permitem o monitoramento da reação de forma contínua, proporcionando um método prático e rápido para a determinação da atividade enzimática. A hidrólise de qualquer ligação da cadeia peptídica entre o grupo doador e o grupo supressor gera fluorescência que permite detectar concentração nanomolar de enzima. Os ensaios podem ser acompanhados diretamente na cubeta ou adaptados para determinações de fluorescência em leitoras de placa. A síntese dos peptídeos com supressão intramolecular de fluorescência contendo o grupo fluorescente Abz (orto-aminobenzóico) e o grupo supressor EDDnp (N-[2, 4-dinitrofenil]-etilenodiamino ou Dnp (2, 4-dinitrophenyl) foi otimizada pelo nosso grupo e tornou-se uma importante linha de pesquisa no Departamento de Biofísica da Universidade Federal de São Paulo. Recentemente, foram desenvolvidas bibliotecas de peptídeos fluorogênico contendo Abz/Dnp como grupo doador/supressor trazendo um grande avanço no estudo de especificidade das peptidases. Esta revisão apresenta o trabalho desenvolvido pelo nosso grupo entre 1993 e 2008 sobre a síntese de peptídeos e o estudo da especificidade de peptidases.