What protects the brain against infection?

The blood-brain barrier (BBB) protects the brain against infection. The BBB is a highly specialized network of blood vessels that surrounds the brain and spinal cord. It acts as a barrier between the circulating blood and the sensitive neural tissue of the central nervous system (CNS).

Here are some key features of the blood-brain barrier that contribute to its protective function:

Tight junctions: The endothelial cells that line the blood vessels of the BBB are tightly connected by specialized junctions called tight junctions. These junctions prevent the passage of most molecules, including potential pathogens, from the blood into the brain.

Efflux pumps: The BBB also contains efflux pumps, which are membrane proteins that actively transport molecules out of the brain. These pumps help to prevent the accumulation of toxic substances, including drugs and bacterial toxins, in the brain.

Nutrient transport: The BBB selectively allows the passage of essential nutrients, such as glucose and amino acids, into the brain. Specialized transport proteins facilitate the movement of these substances across the BBB.

Immune surveillance: The BBB also plays a role in immune surveillance. It contains specialized immune cells, such as microglia and pericytes, that can detect and respond to infections and other threats to the brain.

The blood-brain barrier is essential for maintaining the homeostasis and protecting the delicate neural tissue of the CNS. By tightly regulating the movement of molecules between the blood and the brain, the BBB helps to prevent infections and other harmful substances from reaching the brain.