**Aneta Manda-Handzlik 1,2,\* and Urszula Demkow <sup>1</sup>**


Received: 30 October 2019; Accepted: 18 November 2019; Published: 21 November 2019

**Abstract:** Under normal conditions, neutrophils are restricted from trafficking into the brain parenchyma and cerebrospinal fluid by the presence of the brain–blood barrier (BBB). Yet, infiltration of the central nervous system (CNS) by neutrophils is a well-known phenomenon in the course of different pathological conditions, e.g., infection, trauma or neurodegeneration. Different studies have shown that neutrophil products, i.e., free oxygen radicals and proteolytic enzymes, play an important role in the pathogenesis of BBB damage. It was recently observed that accumulating granulocytes may release neutrophil extracellular traps (NETs), which damage the BBB and directly injure surrounding neurons. In this review, we discuss the emerging role of NETs in various pathological conditions affecting the CNS.

**Keywords:** neutrophil extracellular traps (NETs); Alzheimer's disease; multiple sclerosis; ischemic stroke; meningitis; central nervous system; brain; neurons; brain–blood barrier; neutrophils
