Endothelial proinflammatory signaling is blunted in the P‐selectin knockout mouse

We reported that in high tidal volume ventilation, leukocyte‐endothelial interactions amplify endothelial (EC) proinflammatory signaling as evident in increased tyrosine phosphorylation (TyrP) (AJRCMB, 2005). Here, we determined the role of P‐selectin in these responses. We mechanically ventilated isolated blood‐perfused lungs of wild type (WT) and P‐selectin knockout (P‐selectin−/ −) mice at tidal volume of 18 ml/Kg (HV) and respiratory frequency of 30/min. Mean pulmonary artery, left atrial and end‐expiratory pressures were 12, 6 and 5 cmH2O, respectively. After 1 h of HV, we subjected lysates of freshly recovered lung EC (FLEC) to SDS‐PAGE and Western blotting with anti‐TyrP Ab. TyrP of several EC proteins was greater in WT than in P selectin−/ − mice (P<.05). Confocal microscopy of immunofluorescently labeled FLEC revealed that in WT mice, the integrin αvβ3 both aggregated on the cell‐surface and it co‐localized with vWf. Both responses were abolished in P‐selectin−/ − mice (P<.05). We conclude that P‐selectin ligation augments HV‐induced endothelial TyrP, αvβ3 integrin aggregation and vWf expression. Our findings indicate that HV causes lung recruitment of leukocytes that further augment lung proinflammatory signaling in EC by ligating EC P‐selectin (Support: HL54157).