Expression of the β-chemokines RANTES and MIP-1β by human brain microvessel endothelial cells in primary culture

Abstract

The mechanisms that regulate inflammatory cell recruitment across the blood-brain barrier (BBB) during CNS inflammation have not been fully characterized. Likely players in this process include the chemokines, small secondary messengers of inflammation capable of subset-specific leukocyte activation and chemoattraction. Primary cultures of human brain microvessel endothelial cells (HBMEC) were examined for their in vitro expression of the beta chemokines RANTES and MIP-1β. Untreated HBMEC expressed low levels of RANTES and MIP-1β RNA that were significantly upregulated following cytokine treatment. Parallel studies performed on human umbilical vein endothelial cells (HUVEC) showed induction of RANTES but not MIP-1β RNA. Following stimulation with LPS, TNF-α, IFN-γ, and IL-1β alone or in combination, HBMEC released significant amounts of RANTES and MIP-1β into the culture supernatants. RANTES secretion by HUVEC could be induced only with TNF- α/IFN-γ. Both RANTES and MIP-1β were detected by immunocytochemistry on the apical and basal surfaces of HBMEC, as well as bound to basal lamina-like material under the basal cell surface. Cytokine stimulation induced significant increase of RANTES and MIP-1β molecules associated with the EC surface and subendothelial matrix. The expression of RANTES and MIP-1β by HBMEC suggests that these chemokines may play an important role in mediating inflammatory responses and leukocyte trafficking across the BBB.