The chemokine repertoire of human dermal microvascular endothelial cells and its regulation by inflammatory cytokines

Activation of endothelium is a critical event during the initiation of inflammatory processes and is associated with the induction of cell adhesion molecules and cytokines. The latter include chemotactically active cytokines (chemokines) that promote leukocyte diapedesis from the circulation to sites of evolving inflammation. In this study we evaluated the chemokine repertoire of human endothelial cells derived from the skin (HDMECs) and regulation of these chemokines by cytokines. HDMECs and an immortalized human dermal microvascular endothelial cell line, HMEC-1, were investigated for the expression of C-X-C and C-C chemokines at mRNA and protein levels. Upon stimulation with interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), both HDMECs and HMEC-1 expressed high levels of IL-8, GRO, and monocyte chemoattractant protein-1 (MCP-1). RANTES was only weakly induced; however, concomitant treatment with TNF-α and interferon-γ (IFN-γ) led to upregulation of RANTES, indicating a synergy between these two cytokines. The C-X-C chemokine IFN-inducible protein-10 was upregulated by IFN-γ but not by other cytokines studied. Macrophage inflammatory protein-1α and β, I-309, and ENA-78 could not be induced. The chemokine repertoires of HDMECs and HMEC-1 were compared to those of human umbilical vein endothelium and found to be rather similar with the important exception that IFN-γ and IL-4 up-regulated MCP-1 only in macrovascular endothelium. Our data indicate that HDMECs contribute to the dermal cytokine network by selective production of MCP-1, IL-8, GRO, RANTES, and IP-10, which may critically influence the site-specific recruitment of leukocyte subsets.