Chapter 3.1 - Expression, Functions and Interactions of Chemokines in CNS Trauma

Abstract

This chapter describes the chemokine expression that occurs in central nervous system (CNS) trauma. It reviews the stimulus for chemokine expression within the CNS and discusses the possible roles of chemokines in traumatic CNS injuries. As with classical neuroinflammatory conditions of the CNS such as multiple sclerosis, a traumatic injury to the CNS results in the induction or upregulation of chemokine expression. Elevations of other chemokines are also observed following CNS trauma. A number of chemokines are elevated in CNS trauma. While results may differ in the spectrum of chemokines that are found to be up-regulated as a result of the insult, the rise of chemokines occurs early in the course of traumatic brain injuries. Reported stimuli for chemokine expression in a variety of cell types are the inflammatory cytokines, bacterial products, viruses and other chemotactic factors. Complements including C5a, which itself is a chemotactic source, represent another potential stimulus to increase chemokine expression within the CNS. The most obvious role of cytokines is the recruitment of leukocytes into the CNS. In summary, the chemokines that are expressed in CNS trauma appear to have multiple functions. Finally, the interactions between cytokines, chemokines and matrix metalloproteinases (MMPs) are emphasized. A complex and intricate interaction exists between chemokines, cytokines and MMPs and the individual or sum effect of this on CNS injury and recovery has yet to be elucidated.