A chemical biology investigation of neutrophil extracellular traps

Polymorphonuclear neutrophils are short-lived leukocytes that migrate to infected sites under the acute immune response where they phagocytose, and degranulate to kill microbes. Additionally, neutrophils were found to form Neutrophil Extracellular Traps (NETs). In this process, known as NETosis, the nuclear lobules disappear, the chromatin expands and the DNA is expelled and is decorated with antimicrobial proteins. The signalling mechanisms leading to the formation of NETs are poorly understood. In addition, neutrophils are terminal cells and are not suitable for conventional analytical techniques, which complicate their study using genetic or other biological approaches. Here, we envisage a chemical biology approach to investigate the signalling processes regulating NET formation. The focus of this project is to identify the molecular targets involved in the NET formation process by using chemical inhibitors that may block this process at different stages. At the same time, this approach may lead to the identification of novel therapeutic entities. To achieve this, a screen was first developed using isolated human neutrophils and two commercial library were screened. Here, the inhibition of induced NET formation was analyzed using nuclear morphology and cell viability as readouts in a single protocol. As a result of this screen, we could show that the Raf/MEK/ERK pathway is involved in NET formation through activation of NADPH oxidase and up-regulation of anti-apoptotic proteins. In addition, the screening of a chemical library generated in the group enabled the identification of a tetrahydroisoquinolines a novel compound class inhibitors of NET formation