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Heparin is primarily used as an anticoagulant but has many biological functions as well. It binds with high affinity to a range of cytokines including interferon-γ (IFN-γ) and members of chemokine superfamily. IFN-γ is a proinflammatory cytokine that plays a pivotal role in immune and inflammatory responses; and in endothelial cells, it regulates the expression of fractalkine/CX3CL1 that is a potent agonist for the chemotaxis and adhesion of monocytes and lymphocytes. We have investigated the effect of heparin on the fractalkine expression in human umbilical vein endothelial cells (HUVEC) in culture. HUVEC were treated with ∼100 μg/mL heparin and the expression of the IFN-γ-induced fractalkine mRNA and protein were measured by reverse transcription-PCR and western blotting. The IFN-γ-induced expressions of fractalkine mRNA and protein were inhibited by heparin in a concentration-dependent manner. Heparin also inhibited adhesion of mononuclear cells (MNC) to HUVEC monolayers stimulated with IFN-γ, but it did not inhibit the MNC adhesion to the monolayers stimulated with interleukin-1β. Electrophoretic analysis demonstrated direct binding of heparin to IFN-γ and heparin was found to partially block the binding of IFN-γ to IFN-γ receptor (IFN-γ R). Heparin may play a regulatory role in inflammatory and immune responses by modulating the interaction between leukocytes and the vascular endothelium.

Galectin‐9 is a member of the galectin family and has been identified as an eosinophil chemoattractant produced by activated T lymphocytes. Vascular endothelial cells play an important role in the initial step of eosinophil recruitment and activation in immune and inflammatory responses. We have addressed the stimulation of galectin‐9 expression in endothelial cells. Galectin‐9 was detected in membrane and cytosolic fractions of human umbilical vein endothelial cells stimulated with interferon‐γ (IFN‐γ). IFN‐γ also enhanced the adhesion of human eosinophilic leukemia‐1 cells to endothelial monolayers, and it was inhibited by the presence of lactose. Interleukin‐4, which induces eotaxin expression, did not affect the expression of galectin‐9. The in situ endothelium from patients with inflammatory diseases was found to express galectin‐9. IFN‐γ‐induced production of galectin‐9 by endothelial cells may play an important role in immune responses by regulating interactions between the vascular wall and eosinophils.

Galectin-9 is an eosinophil chemoattractant produced by activated T lymphocytes. We have addressed expression of galectin-9 in normal human astrocytes in culture. Expression of galectin-9 mRNA and protein were examined by reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and immunofluorescent staining. Interleukin-1β (IL-1β) was found to enhance the galectin-9 expression in time- and concentration-dependent manners. Galectin-9 protein was detected in the membrane fraction, 105 000 ×gprecipitate, and immunofluorescent staining revealed diffuse cellular and perinuclear distributions. Dexamethasone pretreatment almost completely suppressed the production. We conclude that astrocytes produce galectin-9 in response to the stimulation with IL-1β, and this may contribute to inflammatory reactions in the CNS.

Soluble form of IL-6 receptor α (sIL-6R) is known to serve as an agonist, without exogenous IL-6, on endothelial cells which do not express IL-6R but have only IL-6 receptor β chain, gp130. We investigated the effect of sIL-6R on fractalkine expression in human umbilical vein endothelial cells (HUVECs) in culture. sIL-6R markedly inhibited HUVEC fractalkine/CX3CL1 expression induced by interleukin (IL)-1α, tumor necrosis factor (TNF)-α, or interferon (IFN)-γ. IL-1α-induced fractalkine expression was inhibited by sIL-6R in time- and concentration-dependent manners. The experiment using actinomycin D indicated that sIL-6R lowered the stability of fractalkine mRNA. The inhibitory effect of sIL-6R was reversed by anti-gp130 neutralizing antibody. sIL-6R inhibited adhesion of mononuclear cells (MNCs) to HUVEC monolayers stimulated with IFN-γ, but it did not inhibit the adhesion to monolayers stimulated with IL-1α. MNC chemotactic activity of conditioned medium of HUVEC stimulated with IL-1α or IFN-γ was inhibited by co-treatment with sIL-6R. sIL-6R may play a regulatory role in immune responses by modulating the interaction between leukocytes and the vascular endothelium.