Complement component anaphylatoxins upregulate chemokine expression by human astrocytes.

The complement (C) system, a major component of the innate immune system, has been described as a factor implicated in some brain disorders. C activation leads to the release of anaphylatoxins, two proinflammatory polypeptides acting through specific receptors that have been detected on brain cells. Here, we examined the effect of anaphylatoxins on chemokine expression by human astrocytes. We showed that anaphylatoxins significantly increase chemokine mRNA expression. However, anaphylatoxin-induced chemokine secretion (interleukin-8) was observed only in the presence of interleukin-1beta. Thus, anaphylatoxins could initiate a chemokine cascade and, at least in part, be involved in pathogenesis of the brain.