Neutrophils and Immunity: From Bactericidal Action to Being Conquered

Abstract

The neutrophil is the major phagocyte and the final effector cell of the innate immunity, with a primary role in the clearance of extracellular pathogens. Using the broad array of cytokines, extracellular traps, and effector molecules as the humoral arm, neutrophils play a crucial role in the host defense against pathogen infections. On the other hand, the pathogen has the capacity to overcome neutrophil-mediated host defense to establish infection causing human disease. Pathogens, such as S. aureus, have the potential to thwart neutrophil chemotaxis and phagocytosis and thereby succeed in evading killing by neutrophils. Furthermore, S. aureus surviving within neutrophils promotes neutrophil cytolysis, resulting in the release of host-derived molecules that promote local inflammation. Here, we provide a detailed overview of the mechanisms by which neutrophils kill the extracellular pathogens and how pathogens evade neutrophils degradation. This review will provide insights that might be useful for the development of novel therapies against infections caused by antibiotic resistant pathogens.

CIRP increases ICAM-1+ phenotype of neutrophils exhibiting elevated iNOS and NETs in sepsis

“…Neutrophils, one of the major cell populations of innate-immune system play a pivotal role in host defense against pathogens [34]. Depletion of neutrophils frequently leads to a fatal complication, while excessive activation of neutrophils results in host tissue damage [35].…”

“…10 Neutrophils, one of the major cell populations of innate-immune system play a pivotal role in host defense against pathogens. 34 Depletion of neutrophils frequently leads to a fatal complication, whereas excessive activation of neutrophils results in host tissue damage. 35 The protective and harmful effects of neutrophils depend on the stages of sepsis, as at the onset of sepsis neutrophils are important in attenuating bacteremia, whereas at the late onset of sepsis prolonged and excessive infiltration of neutrophils often causes organ dysfunction.…”

Immune Dysregulation in Children With Down Syndrome

“…Neutrophils are a crucial effector cell, are the main phagocytes of the innate immune system and play an important role in clearing pathogenic micro-organisms (38). Izumi et al (39) found significantly impaired neutrophil chemotaxis and periodontal disease in adults with DS vs. healthy controls (n = 14 in both groups) which they suggested may have a role in the poorer oral health of this population.…”

More Than Just Attractive: How CCL2 Influences Myeloid Cell Behavior Beyond Chemotaxis

“…Neutrophils defend the host against pathogen infection via phagocytosis, degranulation, and generation of neutrophil extracellular traps and the release of a variety of effector molecules (193). In neutrophils, addition of soluble CCL2 induced the activation of PI3K/Akt, ERK, and NF-κB in vitro, which led to a decrease in constitutive apoptosis in these cells.…”