Decreased systemic polymorphonuclear neutrophil (PMN) rolling without increased PMN adhesion in peritonitis at remote sites

Background: Previous in vitro studies have demonstrated that the host response to intra-abdominal infection produces increased generalized polymorphonuclear neutrophil (PMN) adherence to vascular endothelial cells (ECs), which may lead to subsequent endothelial damage, leaky capillaries, and organ dysfunction. There are scant data to demonstrate this enhanced systemic PMN adherence in vivo or the influence of PMN rolling on PMN endothelial adherence. Hypothesis: Systemic PMN adherence in the animal with sepsis is increased. Design: In vivo murine model of a 2-front infection using intravital microscopy of the cremasteric muscle to quantify PMN-EC adherence in a septic response. Setting: Basic science laboratory and animal surgical facility. Patients or Other Participants: One hundred CD1 male mice. Interventions: Animals underwent cecal ligation and puncture peritonitis, cremasteric muscle Escherichia coli infection, both infections, or neither (controls). Eighteen hours later, the mice underwent exteriorization of the cremasteric muscle under an intravital microscope for measurement of PMN-EC interactions. Blood was then drawn for calculation of circulating PMN counts. Main Outcome Measures: Adherence of PMNs, PMN rolling flux, PMN rolling velocity, and circulating PMN counts. Results: Circulatory mechanics did not differ between the groups. Unlike static in vitro systems, we could not detect an increase in PMN adherence after peritonitis with this dynamic in vivo model. A local (cremasteric) infection was associated with marked PMN adherence. Peritonitis was associated with reduced PMN adherence at a local infection site as well as reduced rolling adhesion and PMN rolling velocity. Conclusions: The data suggest that intra-abdominal infection does not increase remote PMN adherence, and may actually result in reduction of systemic adherence via modulation of PMN rolling.