Prednisolone inhibits cytokine-induced adhesive and cytotoxic interactions between endothelial cells and neutrophils in vitro

We assessed whether prednisolone influenced the ability of human polymorphonuclear neutrophils (PMN) to adhere to and cause lysis of human umbilical vein endothelial cells (HUVEC) in vitro (as measured by the release of ⁵¹Cr). Pretreatment of the endothelium with IL-1β or tumour necrosis factor-alpha (TNF-α) caused prominent endothelial E-selectin expression and endothelial hyperadhesiveness for neutrophils, as well as PMN-mediated cytotoxicity. All these processes were dose-dependently reduced when prednisolone was added to the assay system. This protective effect remained when HUVEC alone were pretreated with the drug prior to washing and cytokine activation. Likewise, when HUVEC cytotoxicity was induced by the nitric oxide (NO) donor S-nitroso-acetyl-penicillamine (SNAP), prednisolone reduced cell injury significantly. In contrast, prednisolone did not interfere with signalling systems between TNF-α-stimulated HUVEC and quiescent PMN such as IL-8 generation and release of cytosolic Ca^2 + in the PMN. Thus, in this in vitro model of vasculitis, prednisolone dose-dependently reduced cytokine-induced E-selectin expression and HUVEC hyperadhesiveness for neutrophils, as well as reducing neutrophil-dependent cytotoxicity against HUVEC via NO-dependent steps.