FIG. 4.

Activated microglia promote inflammatory assault on neurons. A schematic representation of an activated microglial cell and a neuron is depicted here. Microglia, the resident macrophages of the central nervous system (CNS) are activated by and produce cytokines and RNS and ROS that mediate external oxidative stress impacting the neuronal cells. Different insults, such as genetic and environmental factors or aging, affecting the CNS can lead to activation of the CNS–immune system, including lymphocyte recruitment, microglia activation, and astrocyte proliferation. These may in turn induce the production of reactive oxygen species (ROS) or reactive nitrogen species (RNS) and drive the expression of inflammatory factors. Those inflammatory mediators can influence the fate of neurons and stimulate the CNS-immune cells to amplify proinflammatory signals and induce neurotoxic effects. Uncontrolled or chronic inflammation can result in loss of neurons and progression of neurodegenerative diseases.