Title： Homeostatic Behavior of Oxygen and Nitrogen Reactive Species inside Single Phagolysosomes During Phagocytosis by Living Macrophages
Time： 2023-08-14 10:00
Lecturer： Prof. Christian Amatore
Ecole Normale Supérieure, France
Venue： Room 234, Chemistry Building
Abstract：
Oxidative stress involves the formation of superoxide ion by reduction of oxygen and of nitric oxide by reduction of Larginine 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 have been first able to 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.
Bio of Prof. Christian Amatore：
Christian Amatore, 71, is Emeritus Professor of CNRS and ENS and Outstanding Professor of Xiamen University, China. He obtained his Habilitation in University Paris Diderot under Prof Saveant’s guidance before moving to the University of Indiana at Bloomington. He returned to France to CNRS and ENS where he held the former position of Louis Pasteur. He is Member of the French Academy of Sciences, Member of the Academia Europaea, Member of The Third World Academy of Sciences, Foreign Member of the Chinese Academy of Sciences, of the Brazilian Academy of Sciences, and of the Portuguese Academy of Sciences, Honorary Fellow of The Royal Society of Chemistry and of the Chinese Chemical Society, Honorary Member of the Israeli Chemical Society, Distinguished Scientist of the French Chemical Society and Fellow of ISE and ECS. He served as vice-President and President of ISE and was one of the twenty members of the French High Council of Science and Technology, which advised the Presidents of the French Republic. He has been Knighted by the French Republic in the Orders of Merits and of Legion d’Honneur and as Commander of the Order of Academic Palms. He received many important national and international awards and medals among which the Gold Medal of the International Society of Electrochemistry, the Electrochemical Society Plenary Lecturer award, the de Broglie Award from the Lincei, the Nanqiang award from Xiamen University, the Farady Medal from the Royal Society of Chemistry and the Lavoisier Medal from the French Chemical Society.
He published 516 primary publications in top international journals with peer-review accumulating more than 28,800 citations and corresponding to a h-index of 87 (ISI - Web of Knowledge, 07/2023) or more than 36 300 citations and a h-index of 98 (Google Scholar, 07/2023) with an average citations rate larger than 1 250 per year (ISI-WS) or 1 700 (GS) over the past 10 years.
