A Common Language: How Neuroimmunological Cross Talk Regulates Adult Hippocampal Neurogenesis

Figure 1

Neural progenitor cells and immune cells coexist in the hippocampal neurogenic niche. Type 1 neural stem cells in the subgranular zone of the hippocampal dentate gyrus mature through different developmental stages during the multistep process of new neuron formation. Type 1 radial glia-like cells give rise to transiently amplifying progenitor cells (Type 2a/Type 2b). After passing the neuronally committed Type 3 stage the cells become postmitotic after which they integrate as mature granule cells into the existing hippocampal circuitry. Within the complex niche environment peripheral and resident immune cells interact with niche cells to regulate the neurogenic process under physiological conditions. In addition, immune cells in the blood and the niche secrete immune molecules, including cytokines and chemokines, to facilitate neuroimmunological communication.