SÍNDROME DE EVANS COMO UMA MANIFESTAÇÃO TARDIA DA COVID-19

Relato de caso: Paciente de 70 anos, sexo masculino, branco, hipertenso, diabético e portador de insuficiência cardíaca sistólica e doença renal crônica em tratamento por hemodiálise. Durante internação hospitalar por artrite séptica o paciente desenvolveu sintomas gripais e dispneia, com teste reação em cadeia da polimerase em tempo real (RT-PCR) em aspirado de nasofaringe positivo para COVID-19. Permaneceu hospitalizado, desenvolvendo diarreia e hipóxia, tratada com altas doses de oxigênio por máscara facial. Após recuperação completa do quadro clínico de COVID-19, apresentando saturação normal de oxigênio em ar ambiente, passou a apresentar equimoses em extremidades inferiores, em sítios de punção venosa e subcutânea, associada a diminuição progressiva na contagem de plaquetas (57.000/μL). Foram suspensos todos os medicamentos em uso, inclusive heparina dose profilática, frente a hipótese de plaquetopenia induzida por medicamentos. Apesar da medida, na próxima semana houve piora progressiva do quadro clínico e a contagem de plaquetas atingiu 2.000/μL. Foi iniciado tratamento com Metilprednisolona endovenosa e transfusão de plaquetas, considerando o quadro como Púrpura Trombocitopênica Idiopática (PTI). Houve piora progressiva do quadro clínico, mantendo plaquetopenia grave com alto consumo após transfusão, somado a queda progressiva da hemoglobina (6,6 g/dL). Investigação laboratorial revelou sorologias para HIV e HBV negativas, Coombs indireto positivo, alteração de enzimas hepáticas, presença de esferócitos em esfregaço sanguíneo e lactato desidrogenase (LDH) elevado (835u/L), apontando para quadro de hemólise associada. Considerando a possibilidade de síndrome de Evans, foi iniciada infusão de imunoglobulina endovenosa. Não houve resposta satisfatória as intervenções e o paciente evoluiu para óbito duas semanas após o início do quadro hematológico. Discussão: A COVID-19 é uma doença recente, com novas manifestações clínicas e laboratoriais descritas a cada dia. O termo “Long Covid”foi criado para representar as manifestações tardias da COVID-19. Esse relato de caso descreve uma manifestação hematológica, Síndrome de Evans, iniciada após a recuperação de um quadro moderado de COVID-19. A Síndrome de Evans é uma doença rara, caracterizada pela presença concomitante de duas citopenias imunomediadas, mais comumente a PTI e a anemia hemolítica, essa doença apresenta um difícil diagnóstico e um pior prognóstico em relação a outras citopenias isoladas. Conclusão: Espera-se que a partir do conhecimento de que a Síndrome de Evans é uma possível manifestação do COVID-19, eventualmente de forma tardia, o professional da saúde apresente capacidade de realizar esse diagnóstico e tratamento de forma mais precoce e possivelmente mudar o prognóstico do paciente acometido.

Binding of SARS-CoV-2 to the avb6 Integrins May Promote Severe COVID in Patients with IPF

RATIONALE: Patients with idiopathic pulmonary fibrosis (IPF) have worse outcomes following COVID-19. SARS-CoV-2 (2019-nCoV) spike protein (S1) harbors an RGD motif in its receptor-binding domain (RBD). Although SARS-CoV-2 is to exploit human Angiotensin Converting Enzyme-2 (ACE2) receptors for cell entry. Single Cell RNA-seq showed that normal lung expresses low levels of ACE2 with very low expression (1.5%) in Alveolar type 2 epithelial cells. It is possible that SARS-CoV-2 needs a cellular co-receptor, which could include integrins, to promote alveolar cell internalization and pneumonitis.METHODS: Solid-phase binding assays were used to investigate S1 binding to ACE2 or αv containing integrins. Pseudovirus entry assays were used to measure the internalization of SARS-CoV-2 into Human embryonic kidney 293T cells expressing different combinations of potential receptors. RNAscope was used to visualize the co-localization of SARS-CoV-2, ACE2, and integrin mRNAs. Immunohistochemistry was used to evaluate the expression of αvβ6 integrins and ACE2 in lung tissue.RESULTS: Binding assays demonstrated that the RGD containing αvβ3 and αvβ6 integrins bound robustly to the SARS-CoV-2 S1 subunit of Spike protein and overexpression of the αvβ6 integrin modestly augments ACE2 mediated SARS-CoV-2 pseudoviral entry into epithelial cells. In COVID-19 damaged lung ACE2 levels are low but the αvβ6 integrin levels are increased in alveolar epithelium whereas both ACE2 and αvβ6 integrin are increased in lung sections from idiopathic pulmonary fibrosis compared with normal lung samples. CONCLUSION: The SARS-CoV-2 S1 subunit can bind αvβ6 integrins augmenting ACE2-dependent internalization of pseudovirus. In IPF patients, ACE2 levels and αvβ6 integrin levels are increased. Increased binding of the SARS-CoV-2 to ACE2 and the αvβ6 integrin within fibrotic lung may explain the increased risk of severe COVID in patients with IPF.

The novel coronavirus sars-cov-2 binds rgd Integrins and upregulates avb3 integrins in Covid-19 infected lungs

The novel coronavirus SARS-CoV-2 utilizes Angiotensin Converting Enzyme-2 (ACE2) receptors to internalize cells, which are expressed in the nasal and ocular mucosa, and at low levels in the pulmonary epithelium. Despite significant sequence similarities there are substantial differences in transmission dynamics and clinical phenotype between SARS-CoV-2 and SARS-CoV-1. The SARS-CoV-2 spike protein (S1), which is used to internalize cells, contains RGD integrin binding domains which are not present within SARS-CoV-1 S1. We investigated whether SARS-CoV-2 S1 binds integrins while exploring mechanisms that might upregulate ACE2 expression to help explain SARS-CoV-2 viral entry and associated respiratory disease. Lung cell line ACE2 expression was determined using QPCR and western blotting, and in primary lung cells using single cell RNAseq data from publicly available datasets. The effect of IL6 and TGFb on ACE2 expression levels in lung epithelial cells and precision cut lung slices (PCLS) was explored. Solid phase binding assays were used to investigate S1 binding to ACE2 or av containing integrins. Immunohistochemistry was used to stain sections of COVID-19 infected lung tissue for ACE2 and av containing integrins. Single Cell RNA-seq showed that normal lung expresses low levels of ACE2 and only a small proportion of Alveolar type 2 epithelial cells are ACE2 positive (1.5%). Supporting this we found low level ACE2 mRNA and protein expression in small airway epithelial cells, immortalized human bronchial epithelial cells (iHBECs) and A549 cells. IL6 had no effect on ACE2 mRNA or protein expression in the above cells, nor did it affect ACE2 protein in PCLS. TGFb increased ACE2 mRNA in iHBECs and increased ACE2 protein in PCLS. Binding assays demonstrated that SARS-CoV-2 S1 binds avb3 and avb6 integrins in an RGD dependent manner, albeit with a lower affinity than to ACE2. Crucially avb3 integrins are upregulated in COVID-19 infected lung tissue, whereas ACE2 levels remain low even in patients with high viral RNA and protein expression in alveolar tissue. Our data suggests SARS-CoV-2 is able to bind integrins, and may utlise this mechanism to facilitate internalization into lung epithelial cells, which may help explain severe pathology despite low ACE2 expression levels in the lung.