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

唐氏综合症(DS)是最常见的遗传性疾病，大约每800名活产儿中就有一人患有唐氏综合症 以独特的面部外观、智力残疾和发育迟缓为特征的。基因剂量 DS患者的失衡，主要由额外的21号染色体拷贝(21三体)引起，被认为是 有助于一系列共存的医疗疾病。DS常与先天性疾病有关 心脏缺陷(CHD)；大约40%的DS患者有某种形式的CHD，并伴有房室间隔 缺陷(AVSD)是最普遍的。冠状病毒病2019年在全球的迅速传播(新冠肺炎) 由严重急性呼吸综合征冠状病毒2型(SARS-CoV-2)引起的疫情导致了这场持续的大流行。 有趣的是，DS患者更容易感染SARS-CoV-2：患COVID的风险增加4倍- 与没有DS的患者相比，与19相关的住院和与新冠肺炎相关的死亡风险高出10倍。 DS患者更容易感染新冠肺炎的机制在很大程度上尚不清楚。从基因上讲 建立了同源16号染色体三体(MMU16)的工程小鼠，以研究其基因分型。 DS的表型相关性。然而，由于正宗的SARS-CoV-2无法感染老鼠，因为 病毒S蛋白与其受体人血管紧张素的小鼠同源物之间的无效相互作用 转换酶2(ACE2)，用目前的方法总结DS患者的SARS-CoV-2感染并不理想 DS小鼠模型。在这个R21提案中，我们的目标是通过剖析 DS患者使用患者特异性诱导的多能干细胞对新冠肺炎易感性的原因 (IPSCS)。21号染色体编码的一些基因(如跨膜蛋白酶丝氨酸2，TMPRSS2)是 在DS患者中调节失调，并被认为在SARS-CoV-2感染中起作用。我们的中央 假说是DS患者TMPRSS2上调导致肺部SARS-CoV-2感染增强， 导致细胞因子激增，增加了新冠肺炎的严重程度。在具体目标1中，我们将 阐明唐氏综合征在应对SARS时细胞因子激增的机制 使用DS IPSC来源的肺器官类物质感染CoV-2。在特定目标2中，我们将确定基因剂量 TMPRSS2对双链IPSC来源的心肌和内皮细胞感染SARS-CoV-2的影响这是意料之中的 这个项目将对了解DS患者对SARS-CoV-2的易感性产生重大影响 使用临床相关和患者特有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.