TLR4 and central nervous system disorder: In another study, it was observed that the activation of the Toll-like receptor 4 (TLR4) in spinal cord astrocytes triggers a signal flow that leads to the commencement of NF-ĸB, which further initiates the expression of TNF-α, COX-2, and inducible nitric oxide synthase (iNOS), and pro-inflammatory and stress-response moderators that may cause CNS disorders, such as neural cell death.