Regulation of beta-chemokine mRNA expression in adult rat astrocytes by lipopolysaccharide, proinflammatory and immunoregulatory cytokines.

Astrocytes constitute a part of the blood-brain barrier. Chemokine expression by astrocytes may contribute to leucocyte infiltration within the central nervous system (CNS) during inflammation. To investigate factor(s) regulating chemokine expression by astrocytes, we studied the induction of beta-chemokine mRNA expression in adult rat astrocytes. Astrocyte-derived monocyte chemoattractant protein- (MCP-1), RANTES, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta mRNA were induced by interferon-gamma (IFN-gamma). Tumour necrosis factor-alpha (TNF-alpha) induced MCP-1, RANTES and MIP-1beta mRNA expression, and lipopolysaccharide (LPS) induced MCP-1, MIP-1alpha and MIP-1beta mRNA expression in astrocytes. LPS-induced MCP-1, MIP-1alpha and MIP-1beta mRNA expression by astrocytes was antagonized by transforming growth factor (TGF)-beta1 and interleukin (IL)-10. TGF-beta1 and IL-10 also down-regulated MCP-1 and RANTES mRNA expression induced by TNF-alpha. IL-10, but not TGF-beta1, inhibited MIP-1beta mRNA expression induced by TNF-alpha. The results of this in vitro study suggest that beta-chemokine mRNA expression by adult rat astrocytes can be induced by LPS or proinflammatory cytokines, while regulatory cytokines, such as TGF-beta1 and IL-10, down-regulate astrocyte-derived beta-family chemokine mRNA expression induced by LPS, IFN-gamma and TNF-alpha. Further study of CNS chemokines will enhance our understanding of leucocyte recruitment to the CNS and suggest therapeutic strategies for neurological disorders.