Neutrophils in innate and adaptive immunity

Abstract

Neutrophils have long been viewed as short-lived cells crucial for the elimination of extracellular pathogens, possessing a limited role in the orchestration of the immune response. This dogma has been challenged by recent lines of evidence demonstrating the expression of an increasing number of cytokines and effector molecules by neutrophils. Moreover, in analogy with their "big brother" macrophages, neutrophils integrate the environmental signals and can be polarized towards an antitumoural or protumoural phenotype. Neutrophils are a major source of humoral fluid phase pattern recognition molecules and thus contribute to the humoral arm of innate immunity. Neutrophils cross talk and shape the maturation and effector functions of other leukocytes in a direct or indirect manner, through cell-cell contact or cytokine production, respectively. Therefore, neutrophils are integrated in the activation and regulation of the innate and adaptive immune system and play an important role in the resolution or exacerbation of diverse pathologies, including infections, chronic inflammation, autoimmunity and cancer.

Neutrophils Mediate Blood–Spinal Cord Barrier Disruption in Demyelinating Neuroinflammatory Diseases

“…Analyses of mRNA levels in the spinal cord of EAE mice suggest *Centre de Recherche du Centre Hospitalier Universitaire de Québec-Centre Hospitalier de l'Université Laval, Quebec, Quebec G1V 4G2, Canada; † Département de Médecine Moléculaire, Faculté de Médecine, Université Laval, Quebec, Quebec G1V 0A6, Canada; that neutrophils are among the first inflammatory cells recruited into the CNS, which is corroborated by studies showing the presence of PMNs in the meninges before the onset of clinical symptoms (13,17,18). PMNs are also increasingly recognized as having pivotal functions in driving inflammatory processes within the target organ, extending their role beyond that of bystander cells of the adaptive immune response (19)(20)(21). Recent findings present neutrophils as potent modulators of dendritic cell recruitment and function, which themselves are responsible for Ag presentation to encephalitogenic Th1 and Th17 cells following the latter's transmigration from the perivascular space into the parenchyma (22)(23)(24)(25)(26)(27).…”

Interleukin-1 Receptor but Not Toll-Like Receptor 2 Is Essential for MyD88-Dependent Th17 Immunity to Coccidioides Infection

“…Neutrophils can also produce IL-10, a global anti-inflammatory cytokine in lung homogenates of mice during the first 14 days after Coccidioides infection (49). Thus, neutrophils have emerged as components of the effector and regulatory circuits of the innate and adaptive immune systems (50). Vaccinated and challenged C57BL/6 mice reveal early infiltration of neutrophils into lungs at 5 to 7 dpc that is sustained in moderate numbers during the first 14 dpc of Coccidioides infection (6).…”

The immune network in thyroid cancer

“…25 TANs: Tumor associated neutrophils Neutrophils participate to the early phases of inflammation and resistance against extracellular pathogens. 81 However, a role for neutrophils in cancer has been envisaged. Indeed, a new paradigm has been proposed, by which mouse neutrophils can be polarized toward an antitumor N1 or a protumor N2 phenotype in response to signals derived from the microenvironment.…”