Factors in Intestinal Lymph after Shock Increase Neutrophil Adhesion Molecule Expression and Pulmonary Leukosequestration

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Abstract
Because the ischemic gut may produce factors that initiate systemic inflammation, we tested the hypothesis that factors released from the gut into the mesenteric lymphatics increase neutrophil (PMN) adhesion molecule expression after trauma and shock. At 1 and 4 hours after hemorrhagic shock (30 mm Hg x 90 minutes) plus trauma (laparotomy) (T/HS) or sham-shock (T/SS), with or without mesenteric lymph duct ligation, PMN CD11b and CD18 expression was assessed in male rats. In additional rats, mesenteric lymph samples were tested for their ability to increase PMN CD11b expression in vitro. Lastly, at 4 hours after T/SS or T/HS with or without lymph duct ligation, pulmonary PMN sequestration was measured. Compared with T/SS rats, T/HS was associated with up-regulation of PMN CD11b and CD18 expression, which was largely prevented by ligation of the mesenteric lymph duct (p < 0.01). Lymph duct ligation also prevented T/HS-induced pulmonary leukocyte sequestration (p < 0.01). In addition, mesenteric lymph from rats subjected to T/HS but not T/SS increased CD11b expression (p < 0.01). Factors produced or released by the postischemic intestine and carried in the mesenteric lymph appear responsible for PMN activation and pulmonary PMN sequestration after an episode of T/HS.