Systemic not just mesenteric lymph causes acute lung injury following hemorrhagic shock.

Abstract

INTRODUCTION: Recent studies have demonstrated a significant role for factor(s) present in mesenteric lymph following hemorrhagic shock in the etiology of post-hemorrhagic shock acute lung injury (ALI). Earlier studies have shown that ischemia-reperfusion insults to systemic tissue beds can also result in ALI. We therefore hypothesized that factors in systemic lymph may cause lung injury after hemorrhagic shock; this was studied in vitro. METHODS: Confluent human pulmonary microvascular endothelial cells (HMVEC) maintained in a 2-chamber cell culture system were exposed to systemic lymph obtained from dogs exposed to sham operation or hemorrhagic shock and resuscitation. HMVEC injury was indexed by apoptosis (% Apo, Hoechst staining) and permeability to albumin (microL/min). HMVEC activation was indexed by surface expression of intracellular adhesion molecule-1 (ICAM-1) expressed as mean fluorescence intensity using flow cytometry. RESULTS: There was a 2-fold increase in HMVEC permeability and apoptotic rate after incubation with postshock systemic lymph. A similar effect was noted with ICAM expression, which was 2.5 fold higher after incubation with postshock lymph. These biologic effects were first noted with the 120-minute postresuscitation lymph. Lymph obtained during shock or from sham animals had no effect. CONCLUSIONS: Pulmonary microvascular endothelial dysfunction is evident after exposure to lymph obtained from systemic sites after hemorrhagic shock. The "unique" properties ascribed to post-hemorrhagic shock mesenteric lymph in causing ALI seem to be shared by lymph from systemic sites as well.