[Formation of neutrophil extracellular traps and their effects on autoimmune diseases]

Neutrophil extracellular traps(NETs) are networks of extracellular fibers primarily composed of DNA, histones, granular proteins, and cytoplasmic proteins and released to the outside of cells by neutrophils under the stimulation of bacteria, fungi, viruses, parasites, etc. NETs are generated in two forms, suicidal NETs and vital NETs, according to different stimuli. NETs have both anti-inflammatory and pro-inflammatory effects. On the one hand, they can play the anti-microbial role to resist inflammation by capturing, fixing, and killing invading pathogens, which is a special way for neutrophils to exert host defenses. On the other hand, in case of excessive formation or insufficient elimination, they can cause tissue damage directly, and also promote the release of inflammatory factors by recruiting other pro-inflammatory cells or proteins to further expand the inflammatory response, which is related to the pathologies of many diseases. In autoimmune diseases, NETs as important sources of autoantigens, can act as danger-associated molecular patterns( DAMPs) and activate the nucleotide-binding oligomerization domain leucine-rich repeats containing pyrin domain 3(NLRP3) inflammasome and complement system, thereby breaking self-tolerance and accelerating autoimmune inflammation. In addition, NETs can also activate other immune cells(such as B cells, antigen-presenting cells, and T cells) and regulate the acquired immune response. The present study reviewed the correlation of NETs with diseases such as systemic lupus erythematosus(SLE), rheumatoid arthritis(RA), and gouty arthritis(GA) to reveal the effect of dynamic balance between formation and clearance of NETs in autoimmune diseases and provide a theoretical basis for the investigation of underlying mechanisms and targeted therapies of traditional Chinese medicine.