Université de Strasbourg

Fellows seminar - Neutrophil antimicrobial activity in oxygen-free conditions

May 24, 2022
From 15:30 until 17:00
MISHA, Strasbourg

A neutrophil secreting proteoglyfcofili

By Benoît Marteyn, 2020 Fellow

Neutrophils are the most abundant type of immune cells in circulation. When bacteria invade an organ, neutrophils are mobilised to prevent bacteria from spreading in infected tissues. We previously demonstrated that bacteria, such as Shigella, deplete oxygen within infectious foci. We further investigated how neutrophil kill bacteria in the absence of oxygen, since neutrophils can no longer produce reactive oxygen species (ROS) in these conditions.

Neutrophils have been considered to be short-lived cells, thus impairing their study in vitro. We demonstrated that neutrophils are, rather, susceptible to oxygen exposure. Accordingly, we developed innovative methods to purify, manipulate and study neutrophils under controlled pO2 (partial pressure of oxygen) to maintain their basal state. This strategy allowed us to reveal novel neutrophil functions, including the identification of a new antimicrobial mechanism, which consists in the release of a fibrillar compound named proteoglycofili or PGF. PGF are released upon bacterial infections and under anoxic conditions. We demonstrated that PGF has a strong antimicrobial activity (blocking bacteria growth and degrading bacterial virulence factors). PGF is composed of neutrophil degranulated proteins associated to glycosaminoglycans, which are simultaneously released by neutrophils.

Neutrophil PGF may have additional activities beyond the control of bacterial infections, and further investigations will be required to better appreciate its involvement in the formation of cytokine gradients and the recruitment/stimulation of other immune cells.

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