COVID-19 is a highly contagious respiratory disease caused by the novel coronavirus SARS-CoV-2. Since October 2020 the second wave of the pandemic has been observed around the world, as pathogen specific herd immunity has not been built yet. Moreover, the current, more contagious pathogen carrying the D614G mutation has become the globally dominant form of SARS-CoV-2.

In this article we present the current state of knowledge on the impact of ACE2 and the reninangiotensin system (RAS) and the innate immune system on different outcomes of COVID-19. Especially, we point out the dual role of the immune system and ACE2 in pathogenesis of the disease. Namely, at the initial stage of the infection anti-viral activity of innate immunity is responsible for inhibition of SARS-CoV-2 replication. On the other hand, a dysregulated immune response may cause the detrimental hyperinflammation (“cytokine storm”) responsible for the severe course of the disease. Concomitantly, we analyse the roles of ACE2 in both facilitation of infection and abrogation of its effects, as the major cellular entry receptor for SARS-CoV-2 and an important enzyme responsible for tissue protection, respectively. Finally, we discuss the dominant impact of aging on the fatal outcome of COVID-19.

中文翻译：

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免疫系统在 COVID-19 病程中的双重作用。免疫系统老化的致命影响


COVID-19 是由新型冠状病毒 SARS-CoV-2 引起的一种高度传染性呼吸道疾病。自2020年10月以来，由于尚未建立病原体特异性群体免疫，全球出现了第二波疫情大流行。此外，目前携带 D614G 突变的传染性更强的病原体已成为 SARS-CoV-2 的全球主导形式。


在本文中，我们介绍了有关 ACE2 和肾素血管紧张素系统 (RAS) 以及先天免疫系统对 COVID-19 不同结果影响的最新知识。我们特别指出了免疫系统和 ACE2 在疾病发病机制中的双重作用。也就是说，在感染的初始阶段，先天免疫的抗病毒活性负责抑制 SARS-CoV-2 复制。另一方面，免疫反应失调可能会导致有害的过度炎症（“细胞因子风暴”），从而导致疾病的严重病程。与此同时，我们分析了 ACE2 在促进感染和消除其作用方面的作用，分别作为 SARS-CoV-2 的主要细胞进入受体和负责组织保护的重要酶。最后，我们讨论衰老对 COVID-19 致命结果的主要影响。