Acute immune responses in the brain differ from responses in blood

30 September 2016

BPRC - 1. Acute immune responses in the brain differ from responses in blood

Microglia, immune cells of the brain, appear to have been adapted to their challenging environment. They react less destructive to danger signals than their counterparts in the blood.

Microglia are immune cells of the central nervous system (CNS). They are involved in virtually all disorders and diseases of the CNS. Similar cells are present in the other organs. During diseases such as multiple sclerosis both types of cells may be found in the CNS, where they possibly have different roles. BPRC researchers have therefore characterized these celltypes and compared them to eachother.

The investigators isolated these cells (microglia and macrophages) from rhesus monkeys that were euthanized for other reasons. In a culture system they compared the responses of both celltypes to ATP. High concentrations of ATP are released when a cell is damaged, presenting a signal for "danger" for the surrounding (immune) cells. Both microglia and macrophages have specific receptors that detect ATP. Upon detection, the cells secrete a substance called IL-1β, which  attracts and activates other immune cells.

The secretion of IL-1β after exposure to ATP was shown to be significantly lower by microglia than by macrophages. The researchers demonstrated that this may be a result of a more limited number of receptors on the surface of microglia. Microglia are in their natural environment already exposed to high levels of ATP, since this compound is also important for the signaling between different nerve cells.

This work is described in the scientific journal Glia (http://onlinelibrary.wiley.com/doi/10.1002/glia.23059/abstract;jsessionid=21D4435E5F2080D44AEC40F7E73DB60B.f01t02). This knowledge may contribute to the identification of new leads for the development of therapies that will inhibit or stimulate microglia or macrophages. For various neurological disorders, there is a great need for such medications.