Discovery of ACE2 (angiotensin-converting enzyme 2) revealed that the renin-angiotensin system has 2 counterbalancing arms. ACE2 is a major player in the protective arm, highly expressed in lungs and gut with the ability to mitigate cardiopulmonary diseases such as inflammatory lung disease. ACE2 also exhibits activities involving gut microbiome, nutrition, and as a chaperone stabilizing the neutral amino acid transporter, B0AT1, in gut. But the current interest in ACE2 arises because it is the cell surface receptor for the novel coronavirus, severe acute respiratory syndrome coronavirus-2, to infect host cells, similar to severe acute respiratory syndrome coronavirus-2. This suggests that ACE2 be considered harmful, however, because of its important other roles, it is paradoxically a potential therapeutic target for cardiopulmonary diseases, including coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2. This review describes the discovery of ACE2, its physiological functions, and its place in the renin-angiotensin system. It illustrates new analyses of the structure of ACE2 that provides better understanding of its actions particularly in lung and gut, shedding of ACE2 by ADAM17 (a disintegrin and metallopeptidase domain 17 protein), and role of TMPRSS2 (transmembrane serine proteases 2) in severe acute respiratory syndrome coronavirus-2 entry into host cells. Cardiopulmonary diseases are associated with decreased ACE2 activity and the mitigation by increasing ACE2 activity along with its therapeutic relevance are addressed. Finally, the potential use of ACE2 as a treatment target in COVID-19, despite its role to allow viral entry into host cells, is suggested.

中文翻译：

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ACE2（血管紧张素转换酶 2）在心肺疾病中的作用

ACE2（血管紧张素转换酶 2）的发现表明肾素-血管紧张素系统有 2 个平衡臂。ACE2 是保护臂的主要参与者，在肺和肠道中高度表达，具有减轻心肺疾病（如炎症性肺病）的能力。ACE2 还表现出涉及肠道微生物组、营养和作为稳定肠道中中性氨基酸转运蛋白 B0AT1 的伴侣的活动。但目前对 ACE2 的兴趣之所以产生，是因为它是新型冠状病毒严重急性呼吸综合征冠状病毒 2 的细胞表面受体，可以感染宿主细胞，类似于严重急性呼吸综合征冠状病毒 2。这表明 ACE2 被认为是有害的，然而，由于其重要的其他作用，自相矛盾的是，它是心肺疾病的潜在治疗靶点，包括由严重急性呼吸系统综合症冠状病毒 2 引起的 2019 年冠状病毒病 (COVID-19)。这篇综述描述了 ACE2 的发现、它的生理功能以及它在肾素-血管紧张素系统中的位置。它说明了对 ACE2 结构的新分析，可更好地了解其作用，尤其是在肺和肠道中的作用、ADAM17（一种去整合素和金属肽酶结构域 17 蛋白）对 ACE2 的脱落，以及 TMPRSS2（跨膜丝氨酸蛋白酶 2）在严重急性呼吸综合征冠状病毒-2 进入宿主细胞。心肺疾病与 ACE2 活性降低有关，通过增加 ACE2 活性及其治疗相关性来缓解。最后，ACE2 作为 COVID-19 治疗目标的潜在用途，