Dissecting SARS-CoV-2 infection in Down syndrome with congenital heart defects using patient-specific iPSCs

唐氏综合征（DS）是最常见的遗传性疾病，每800名活产婴儿中约有1名发生， 以独特的面部外观、智力残疾和发育迟缓为特征。基因剂量 DS患者的失衡主要是由21号染色体的额外拷贝（21三体）引起的，被认为是 有助于广泛的共存的医疗条件。DS常与先天性 心脏缺陷（CHD）;大约40%的DS患者患有某种形式的CHD，伴房室间隔 缺陷（AVSD）是最普遍的。2019冠状病毒病（COVID-19）在全球迅速蔓延 由严重急性呼吸综合征冠状病毒2型（SARS-CoV-2）引起的流感导致了持续的大流行。 有趣的是，DS患者更容易感染SARS-CoV-2：COVID-1的风险增加了4倍。 19-相关的住院治疗和10倍的高风险COVID-19相关的死亡相比，没有DS的患者。 DS患者更容易感染COVID-19的机制在很大程度上尚不清楚。基因 开发了同源染色体16（MMU 16）三体的工程小鼠，以研究基因型- DS中的表型相关。然而，由于真正的SARS-CoV-2无法感染小鼠， 病毒S蛋白与其受体的小鼠直系同源物人血管紧张素之间的无效相互作用 转换酶2（ACE 2），使用当前的方法重现DS患者中的SARS-CoV-2感染并不理想。 DS小鼠模型。在这个R21提案中，我们的目标是通过解剖机械来弥合这一知识差距。 使用患者特异性诱导多能干细胞研究DS患者对COVID-19易感性的原因 （iPSC）。由21号染色体编码的一些基因（例如跨膜蛋白酶丝氨酸2，TMPRSS 2）是 在患有DS的个体中失调，并且已经暗示在SARS-CoV-2感染中起作用。我们的中央 假设DS中TMPRSS 2的上调导致肺中SARS-CoV-2感染增强， 导致细胞因子激增，增加COVID-19的严重程度。具体目标1： 阐明唐氏综合征患者对SARS反应中细胞因子激增的机制， 使用DS iPSC衍生的肺类器官的CoV-2感染。在具体目标2中，我们将确定基因剂量 TMPRSS 2对DS iPSC衍生的心脏和内皮细胞中SARS-CoV-2感染的影响。预计 该项目将对了解DS患者对SARS-CoV-2的易感性产生重大影响 使用临床相关的和患者特异性的心脏和肺细胞进行感染。

Down syndrome (DS) is the most common genetic disorder occurring in about 1 in 800 live births, and is characterized by a distinctive facial appearance, intellectual disability, and developmental delays. Gene dosage imbalance in DS patients, primarily caused by an extra copy of chromosome 21 (trisomy 21), is thought to contribute to a broad spectrum of coexisting medical conditions. DS is frequently associated with congenital heart defects (CHDs); approximately 40% of DS patients have some form of CHD, with atrioventricular septal defects (AVSD) being the most prevalent. The swift global spread of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the ongoing pandemic. Intriguingly, DS patients are more vulnerable to SARS-CoV-2 infection: there is a 4-fold increased risk for COVID- 19-related hospitalization and a 10-fold higher risk for COVID-19-related death compared to patients without DS. Mechanisms by which individuals with DS are more susceptible to COVID-19 are largely unknown. Genetically engineered mice made trisomic for homologous chromosome 16 (MMU16) were developed to study genotype- phenotype correlations in DS. However, because authentic SARS-CoV-2 is unable to infect mice due to the inefficient interaction between the viral S-protein and the mouse orthologue of its receptor, human angiotensin converting enzyme 2 (ACE2), it is not ideal to recapitulate SARS-CoV-2 infection in DS patients using current DS mouse models. In this R21 proposal, we aim to bridge this knowledge gap by dissecting the mechanistic causes of the susceptibility of DS patients to COVID-19 using patient-specific induced pluripotent stem cells (iPSCs). Some genes encoded by chromosome 21 (e.g. transmembrane proteinase serine 2, TMPRSS2) are dysregulated in individuals with DS and have been implicated to have a role in SARS-CoV-2 infection. Our central hypothesis is that upregulation of TMPRSS2 in DS leads to enhanced SARS-CoV-2 infection in the lungs, resulting in an enhanced cytokine surge that increases the severity of COVID-19. In Specific Aim 1, we will elucidate the mechanisms underlying the enhanced cytokine surge in Down syndrome in response to SARS- CoV-2 infection using DS iPSC-derived lung organoids. In Specific Aim 2, we will determine the gene-dosage effect of TMPRSS2 on SARS-CoV-2 infection in DS iPSC-derived cardiac and endothelial cells. It is expected that this project will have a major impact on the understanding of susceptibility of DS patients to SARS-CoV-2 infection using clinically relevant and patient-specific cardiac and lung cells.