Dexamethasone inhibits arteriolar leukocyte rolling and adhesion induced by tumor necrosis factor-α in vivo

Objective: Glucocorticoids are widely used in vasculitis syndromes, however, the protective mechanisms remain to be elucidated. In this study, we wanted to examine the effect of dexamethasone on leukocyte rolling and adhesion in arterioles in vivo. Materials and Methods: NMRI mice were treated intrascrotally with tumor necrosis factor-alpha (TNF-alpha) for 3-4 h. Intravital microscopy was used to study leukocyte-endothelium interactions in arterioles in the cremaster muscle. Results: It was found that TNF-alpha markedly increased the number of rolling and adherent leukocytes in the arterioles. Pretreatment (2 h) with dexamethasone significally reduced TNF-alpha-induced leukocyte rolling and adhesion. In fact, 1 mg/kg of dexamethasone decreased leukocyte rolling and adhesion by 76% and 87%, respectively. Conclusions: These findings suggest that the beneficial effect of dexamethasone in vasculitis disorders may in part be attributable to an inhibitory impact on cytokine-induced leukocyte rolling and adhesion in arterioles.