ISCR 2023 conferences - Christian Amatore

Quantitative and selective measurements of sub-millisecond dynamics of ROS/RNS production during phagocytosis with a nanoelectrochemical sensor
ISCR 2023 conferences - Christian Amatore

The Rennes Institute of Chemical Sciences (ISCR) is pleased to welcome in Rennes Christian Amatore (PASTEUR, Sorbonne University, Paris
& State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, China).

Oxidative stress involves the formation of superoxide ion by reduction of oxygen and of nitric oxide by reduction of L-arginine which lead to a cascade of reactions producing species known as "free radicals" or “Reactive Oxygen or Nitrogen Species” (ROS or RNS, accordingly) and whose consequences onto the organisms can be deleterious (inflammation, ageing, cancers, autoimmune diseases, Parkinson's or Alzheimer diseases, etc.). Thus, ROS, RNS and oxidative stress are often perceived as harmful.

However, this negative view is not correct, because ROS & RNS have simultaneously important positive effects. It is for example the oxidative stress which allows macrophages to eliminate viruses, bacteria and damaged or dead cells, etc., during phagocytosis. This occurs within intracellular organelles named phagolysosomes in which macrophages engulf the entities to digest.

However, a key point for survival is that macrophages should not suffer themselves from the ROS and RNS that they generate in these processes. So biologists and MD’s have long hypothesized that the concentration of ROS and RNS inside activated phagolysosomes is maintained at a sufficient level to perform the sought function while remaining lower than the capacities of the macrophage defense.

In agreement with this hypothesis, using platinized nanoelectrodes, we could monitor very transient and vanishingly small ROS and RNS fluxes spilling out of phagolysosomes during phagocytosis evidencing that macrophages are equipped to rapidly eradicate them. Even smaller platinized nanoelectrodes allowed us to establish for the first time the existence of the long sought homeostatic process occurring inside phagolysosomes and quantity it with adequate chemical and kinetic resolution.

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Contacts

  • Ie-rang Jeon, Univ Rennes, ISCR-CNRS UMR 6226, F-35000 Rennes, France
    ierang [dot] jeonatuniv-rennes [dot] fr
     
  • Philippe Hapiot, Univ Rennes, ISCR-CNRS UMR 6226, F-35000 Rennes, France
    philippe [dot] hapiotatuniv-rennes [dot] fr

 

Published September 22, 2023