Cytoplasmic receptors recognizing nucleic acids and mediating immune functions in neutrophils

- Neutrophils constitutively express several cytoplasmic RNA and DNA sensors.
- Neutrophils promptly respond to intracellular synthetic dsRNA and plasmid DNA.
- The TBK1/IRF3 axis is functional in appropriately stimulated human neutrophils.
- Neutrophils may play important immunological roles toward intracellular pathogens.

Cells belonging to the innate immune system, including neutrophils, rapidly respond to invading microorganisms by recognizing a wide range of microbial-derived products referred to as pathogen-associated molecular patterns (PAMPs). Generally speaking, PAMPs include molecular structures associated with microbial envelopes (such as bacterial lipopolysaccharide, lipoproteins, and flagellin) and microbial nucleic acids. PAMPs bind to and activate various families of germline-encoded receptors carried by cells of the innate immune system, known as pattern-recognition receptors (PRRs). This group of receptors, located in various subcellular compartments, in turn generates a series of intracellular signaling pathways that coordinately modulate the transcription of hundreds of inflammatory genes, the products of which directly control infection and/or contribute to promote the development of the innate and adaptive immune responses. Herein, we summarize current knowledge on neutrophil recognition and response to foreign cytoplasmic nucleic acids.