Mechanism of Bacterial Traversal across the Blood Brain Barrier

The BBB (blood brain barrier), composed mainly of specialized brain microvascular endothelial cells, is an important membrane barrier that maintains biochemical homeostasis in the CNS (central nervous system). Bacteria use a variety of different virulence factors that enable them to attach to and invade microvascular endothelial cells or phagocytes through receptor-mediated recognition and adhesion mechanism. Endocytosis, exocytosis, and migration can be manipulated by these bacteria through host cell signaling and inflammatory response mechanisms, which will facilitate traversal of BBB via transcellular passage, paracellular passage and “Trojan horse” mechanism. Based on the crossing mechanism of BBB applied by typical meningitis bacteria, hypothesis of BBB traversal by Salmonella oral infection is proposed which may serve as hints for neuropathogenic mechanism of this enterobacteria.