Abstract
Effectively treating infectious diseases often requires a multi-step approach to target different components involved in disease pathogenesis. Similarly, the COVID-19 pandemic has become a global health crisis that requires a comprehensive understanding of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) infection to develop effective therapeutics. One potential strategy to instill greater immune protection against COVID-19 is boosting the innate immune system. This boosting, termed trained immunity, employs immune system modulators to train innate immune cells to produce an enhanced, non-specific immune response upon reactivation following exposure to pathogens, a process that has been studied in the context of in vitro and in vivo clinical studies prior to the COVID-19 pandemic. Evaluation of the underlying pathways that are essential to inducing protective trained immunity will provide insight into identifying potential therapeutic targets that may alleviate the COVID-19 crisis. Here we review multiple immune training agents, including Bacillus Calmette-Guérin (BCG), β-glucan, and lipopolysaccharide (LPS), and the two most popular cell types involved in trained immunity, monocytes and natural killer (NK) cells, and compare the signaling pathways involved in innate immunity. Additionally, we discuss COVID-19 trained immunity clinical trials, emphasizing the potential of trained immunity to fight SARS-CoV-2 infection. Understanding the mechanisms by which training agents activate innate immune cells to reprogram immune responses may prove beneficial in developing preventive and therapeutic targets against COVID-19.
Highlights
Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2), the most recent coronavirus to emerge, has led to the COVID-19 pandemic
There is evidence that innate immune cells are significantly altered during SARS-CoV-2 infection, with severe COVID-19 patients displaying lower levels of total monocytes [5] and a decreased number and activity of natural killer (NK) cells [6]
To evaluate trained immunity in the era of COVID-19, this review focuses on an overview of trained immunity mechanisms and their impact on COVID-19
Summary
Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2), the most recent coronavirus to emerge, has led to the COVID-19 pandemic. There is evidence that innate immune cells are significantly altered during SARS-CoV-2 infection, with severe COVID-19 patients displaying lower levels of total monocytes [5] and a decreased number and activity of natural killer (NK) cells [6]. To evaluate trained immunity in the era of COVID-19, this review focuses on an overview of trained immunity mechanisms and their impact on COVID-19 We describe both individual immune training agents and different innate immune cell types to distinguish specific pathways through which trained immunity can be induced. A thorough understanding of these pathways and the subsequent trained immune responses is critical to evaluate how trained innate immunity can be exploited to SARS-CoV-2 infection. Harnessing the capabilities of trained immunity for COVID-19 first requires an understanding of the pathways responsible for mediating this heterologous immunity and which training agent(s) induce these immunological modifications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
