Understanding the molecular mechanisms of NETs and their role in antiviral innate immunity

- Activated neutrophils can release NETs.
- NETs are formed by proteases, chromatin, and antimicrobial proteins.
- The main function of NETs is to trap and kill microbes avoiding their scatter.
- Virus are able to induce NET formation by human neutrophils in vitro.

Polymorphonuclear neutrophils (PMNs) are the most abundant cells in the context of innate immunity; they are one of the first cells to arrive at the site of viral infection constituting the first line of defense in response to invading pathogens. Indeed, neutrophils are provided with several defense mechanisms including release of cytokines, cytotoxic granules and the last recently described neutrophil extracellular traps (NETs). The main components of NETs are DNA, granular antimicrobial peptides, and nuclear and cytoplasmic proteins, that together play an important role in the innate immune response. While NETs were first described as a mechanism against bacteria and fungi, recently, several studies are beginning to elucidate how NETs are involved in the host antiviral response and the prominent characteristics of this new mechanism are discussed in the present review.