Biological role of Toll-like receptor-4 in the brain.

The Toll-like receptors (TLRs) are a family of microbe-sensing receptors that play a central role in the regulation of the host immune system. TLR4 has been described in the brain and seems to regulate some physiological processes, such as neurogenesis. TLR4 has also been reported to play a role during neurodegenerative disorders, including Alzheimer's disease, amyotrophic lateral sclerosis, multiple sclerosis and Parkinson's disease. This review is focused on reports concerning recent insights into the role and activation mechanisms of TLR4 in the brain, in pathological and physiological conditions, as well as the therapeutic benefit that could derive from TLR4 modulation.