Cytokine-induced pericyte shape change can occur in a neutrophil-independent manner. TNF or IL-1β were injected i.s. into WT C57BL/6 mice and cremaster muscles were dissected at different time points after stimulation, fixed, immunostained for pericytes (αSMA, red) and neutrophils (MRP-14, green) and analyzed by confocal microscopy. (A) Representative images from TNF- (left) and IL-1β–stimulated (right) cremasteric venules illustrating the neutrophil infiltration responses obtained at the 4-h time point. Bars, 10 µm. (B) Time course of cytokine-induced increase in mean gap size between adjacent pericytes (top) and neutrophil transmigration (bottom) in response to TNF- (left) and IL-1β–(right). Statistically significant cytokine-induced responses, as compared with responses noted in unstimulated tissues, are indicated by *asterisks. *, P < 0.05; **, P < 0.01; ***, P < 0.001. Significant differences between responses at different time points are indicated by hash symbols. #, P < 0.05; ##, P < 0.01; ###, P < 0.001. (C) WT mice were depleted of their circulating neutrophils using an anti-GR1 antibody (100 µg, i.p.) 24 h before i.s. injection of TNF or IL-1β. Control mice were treated with an isotype control antibody. Mean size of pericyte gaps was quantified at 2 h (TNF) or 4 h (IL-1β) after stimulation. Significant differences from unstimulated controls are indicated by asterisks. *, P < 0.05; ***, P < 0.001. n = 3–4 experiments for (at least 4 vessels analyzed per animal per experiment).