Leukocyte-endothelium interactions after hemorrhagic shock/reperfusion and cecal ligation/puncture: an intravital microscopic study in rat mesentery

Hemorrhagic shock/reperfusion (HS/R) followed by sepsis triggers systemic microcirculatory disturbances that may induce multiple organ failure. The present study evaluated the effects of HS/R and cecal ligation and puncture, followed by necrotic cecal resection/peritoneal lavage (REL) on leukocyte-endothelium interactions at the mesentery. Eighty-one anesthetized Wistar rats (200-250 g) were randomly assigned to a first injury: (1) control-HS-no hemorrhagic shock/no reperfusion group, (2) HS/blood-HS/R with 25% shed blood, and (3) HS/blood + LR-HS/R with 25% of the shed blood + lactated Ringer's solution, 3x shed blood volume. Twenty-four hours post-HS/R, animals were submitted to cecal ligation and puncture and, 24 h thereafter, to REL. Leukocyte-endothelium interactions were assessed by intravital microscopy and intercellular adhesion molecule (ICAM) 1 and P-selectin expression by immunohistochemistry. Lungs were observed for ICAM-1 expression and neutrophil infiltration. Single and double injury induced significant increases in rolling (approximately 2-fold), adherent (approximately 5-fold), and migrated leukocytes (approximately 7-fold); ICAM-1 expression (approximately 1/2-fold), and P-selectin expression (approximately 1/2-fold) at the mesentery compared with control-HS group. REL normalized leukocyte-endothelium interactions at the mesentery in single-injured animals. However, in double-injured rats, adherence and migration of leukocytes decreased but did not normalize. Similar results were observed on ICAM-1 expression and neutrophil infiltration in the lungs from these animals. In conclusion, the current in vivo observation of the mesenteric microcirculation after a double injury followed by REL is a suitable model for the systematic evaluation of the inflammatory reaction at local and distant sites. In addition, data presented herein emphasized the importance of surgical removal of the septic focus in controlling the otherwise lethal sepsis-induced multiple organ dysfunction syndrome.