Neutrophil-derived chemokines on the road to immunity

Highlights • Neutrophils represent a cellular source of chemokines. • Neutrophils recruit and activate, via chemokines, discrete leukocyte populations. • Neutrophils, in virtue of their capacity to recruit innate and adaptive immunity cells via chemokines, potentially orchestrate sophisticated immune responses. • Neutrophil-derived chemokines contribute to the pathogenesis of infectious and non-infectious diseases.
During recent years, it has become clear that polymorphonuclear neutrophils are remarkably versatile cells, whose functions go far beyond phagocytosis and killing. In fact, besides being involved in primary defense against infections–mainly through phagocytosis, generation of toxic molecules, release of toxic enzymes and formation of extracellular traps–neutrophils have been shown to play a role in finely regulating the development and the evolution of inflammatory and immune responses. These latter neutrophil-mediated functions occur by a variety of mechanisms, including the production of newly manufactured cytokines. Herein, we provide a general overview of the chemotactic cytokines/chemokines that neutrophils can potentially produce, either under inflammatory/immune reactions or during their activation in more prolonged processes, such as in tumors. We highlight recent observations generated from studying human or rodent neutrophils in vitro and in vivo models. We also discuss the biological significance of neutrophil-derived chemokines in the context of infectious, neoplastic and immune-mediated diseases. The picture that is emerging is that, given their capacity to produce and release chemokines, neutrophils exert essential functions in recruiting, activating and modulating the activities of different leukocyte populations.