Phagocytosis and neutrophil extracellular traps

Abstract

Neutrophils are recruited rapidly to sites of infection in response to host- and/or microbe-derived proinflammatory molecules. At such sites, neutrophils phagocytose microbes and are activated to produce superoxide and other reactive oxygen species (ROS). In addition, neutrophils contain stores of antimicrobial peptides and enzymes that work in concert with ROS to kill ingested microbes. Neutrophils can also release chromosomal DNA bound with antimicrobial peptides and enzymes to form web-like structures known as extracellular traps. Neutrophil extracellular traps (NETs) have been reported to ensnare and kill microbes and are commonly considered to be an important component of innate host defense. Notably, the formation of NETs is most often reported as a cytolytic process. Whereas intraphagosomal killing of microbes sequesters cytotoxic antimicrobial molecules that would otherwise damage host tissues, the formation of NETs and associated extracellular release of these molecules can contribute to host tissue destruction and disease. Here we compare and contrast phagocytosis and NETs in host defense, with emphasis on recent studies of NETs that ultimately underscore the importance of phagocytosis as the primary means by which neutrophils eliminate microbes.

Integrated Network Analysis to Identify Key Modules and Potential Hub Genes Involved in Bovine Respiratory Disease: A Systems Biology Approach

“…In response to signaling proinflammatory cytokines and chemokine such as IL8 , neutrophils are the first cells to migrate from the blood to the infection site ( Kolaczkowska and Kubes, 2013 ). These cells play an important role in killing extracellular pathogens through phagocytosis ( Nordenfelt and Tapper, 2011 ; DeLeo and Allen, 2020 ). Neutrophil-related biological processes and KEGG pathways in the turquoise module included “neutrophil mediated immunity,” “neutrophil degranulation,” “neutrophil activation involved in immune response,” and “neutrophil extracellular trap formation.” However, neutrophils play an important role in the pathogenesis of BRD by destruction and damaging lung tissue during infection ( McGill and Sacco, 2020 ).…”

Citrullination in the pathology of inflammatory and autoimmune disorders: recent advances and future perspectives

“…Neutrophils, a subclass of blood granulocytes, constitute the vanguard of the human innate immune response to invading pathogens: bacteria, fungi and viruses [ 86 , 87 ]. Their modes of action include: phagocytosis—consisting of the direct engulfing of pathogens, production of reactive oxygen species (ROS) and release of cytokines and chemokines, which recruit other immune cells and enhance the host immune response [ 88 , 89 ].…”

Immune System Disequilibrium—Neutrophils, Their Extracellular Traps, and COVID-19-Induced Sepsis

“…Dysregulated NETosis may lead to the development and exacerbation of several autoimmune and chronic infectious or inflammatory diseases (82). NETS have also been associated with multiple types of neoplastic processes (83). NETs can be released in a process of suicidal NETosis, where the neutrophil ruptures, or vital NETosis, where NETs are exocytosed from neutrophils in vesicles (84).…”