学术报告
报告题目：Nano-Electrochemical Measurements of ROS and RNS Homeostasis During Phagocytosis by Macrophages
报告时间：2024-03-07 10:00
报告人： Christian Amatore（法国巴黎高等师范学校）
法国科学院院士，欧洲科学院院士，中国科学院外籍院士
报告地点：卢嘉锡楼202报告厅
转播地点：翔安校区能源材料大楼3号楼会议室5，漳州校区生化主楼307教室
报告摘要：
Oxidative stress involves the formation of superoxide radical ions by reduction of oxygen and of nitric oxide radicals 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.
A key point for macrophages’ survival is that they should not suffer themselves from the ROS and RNS that they generate in these processes. So biologists and MD’s have hypothesized that the concentration of ROS and RNS inside activated phagolysosomes is maintained at a sufficient levels to perform the sought functions while remaining lower than the capacities of the macrophage defense.
Using specifically designed platinized SiC nanoelectrodes, we could monitor very transient and vanishingly small ROS and RNS fluxes produced inside phagolysosomes during phagocytosis evidencing that macrophages are equipped to rapidly eradicate them. This allowed us to establish and quantify for the first time the existence of the long-hypothesized homeostatic process occurring inside phagolysosomes.
However, when macrophages try to phagocytose inert micro/nanofibers which are immune to ROS and RNS, the very homeostatic process provokes a continuous spilling of intense fluxes of these species onto the underlying cells of the tissue that macrophages patrol to protect. We will show that this may be the real cause of fibrosis and pleural cancers induced by nanofibers such as asbestos.
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