PMN TRANSMIGRATION THROUGH ENDOTHELIUM IS ENHANCED BY THE COMBINED INJURY OF BURN AND INFECTION

Abstract

PMNs are important in the host defense against microbes. PMNs also play an important role in tissue damages in injury conditions. We showed that the combined injury of burn (B) and infection (CLP) increased PMN accumulation in the intestine and intestinal microvascular permeability to albumin. Those changes were greater in the combined injury than B or CLP alone. Activated PMNs, increased chemoattractants, or both appeared to be responsible for those changes. In order to evaluate PMN contribution to those changes, we studied PMN transmigration and albumin permeability through the endothelium using endothelial monolayers in vitro in the present study. Materials and Methods Male Sprague-Dawley rats were divided into 4 groups: B group (30% total body surface area), CLP group, B+CLP group, and sham (S) group. One day after the injury, blood was collected and PMNs were isolated. A rat microvascular endothelial cell-line was cultured on 3 μm pore filter inserts in 24-well plates. When confluent endothelial cell monolayers (END) developed, the isolated PMNs and I125 -albumin were placed on END and cultured for an hour. PMNs and I125 -albumin, which passed through END, were counted. PMN productions of reactive oxygen species (ROS) and elastase were also observed. Results Both ROS and elastase productions increased in B+CLP group more than B or CLP groups. Ecadherin decreased in B+CLP group more than B or CLP groups.FigureConclusion PMNs play an important role in the enhancement of PMN transmigration in the combined injury of B + CLP. (Supported by NIH RO1 grants GM53235 and GM56865, and Folk research foundation.)