No abstract

The effect of different concentrations (0.06, 0.6 and 6.0 mmol/L) of ascorbic acid on neutrophil-endothelial interaction was studied using an in vitro model of human umbilical cord vein endothelial cells and human neutrophils. The aim of the study was to determine changes in chemiluminescence response of neutrophils during adherence to endothelial cells. Because adherence of neutrophils to endothelial cells is an essential component in inflammatory processes leading to endothelial cell injury, the influence of ascorbic acid on adherence and endothelial cell injury have been investigated. Production of oxygen-derived metabolites, measured by chemiluminescence response of neutrophils, decreased significantly in the presence of 6 mmol/L ascorbic acid during coincubation of neutrophils and endothelial cells (p < 0.025). The adherence of neutrophils to endothelial cells was significantly decreased at a concentration of 6 mmol/L (p < 0.0005). The inhibition of neutrophil adherence to endothelial cells was correlated with a diminished neutrophil-mediated endothelial cell injury during incubation with 6 mmol/L ascorbic acid (p < 0.0005). The present results indicate that ascorbic acid might exert a protective effect on neutrophil-mediated endothelial cell injury by decreasing adherence of neutrophils to endothelial cells and by scavenging reactive oxygen metabolites. Moreover, the current investigation points to probable protective effect of ascorbic acid on oxidant-mediated cell damage in diseases (e.g., Adult Respiratory Distress Syndrome).

In the recent years the essential role of granulocytes in the initiation and amplification of the pathomechanisms resulting in the adult respiratory distress syndrome (ARDS) has been documented [3, 5-7]. On the contrary, there is only little information about the participation of alveolar macrophages in the ARDS pathogenesis [4] and no report on alterations of macrophage functions during the development of the ARDS.

The trauma-induced activation of neutrophils and their functional alterations, i.e., increase in adherence and release of oxygen derived metabolites, is considered to play a central role in the initiation and amplification of capillary endothelial cell damage and following organ failure. In the present study neutrophil-endothelial cell interaction was studied using an in vitro model of human umbilical cord vein endothelial cells and human neutrophils. Production of oxygen-derived metabolites was determined by comparing mean peak chemiluminescence of neutrophils from multiply traumatized patients (n = 40) and mean peak chemiluminescence of neutrophils from blood donors (n = 160). Adherence and endothelial injury by neutrophils of multiply traumatized patients were compared with data of healthy blood donors. Chemiluminescence response of 70,000 neutrophils isolated from healthy control individuals was 699 +/- 98 x 10(3) cpm and could be increased significantly by endothelial cells to 1410 +/- 135 x 10(3) cpm (p < 0.05). Chemiluminescence response to neutrophils of polytraumatized patients was 1174 +/- 94 x 10(3) cpm and could not be significantly increased by endothelial cells (1419 +/- 120 x 10(3) cpm). Adherence of neutrophils of blood donors to endothelial cells was 12.31 +/- 0.77%. Adherence of neutrophils of polytraumatized patients was significantly increased to values of 24.83 +/- 2.03%. Injury of endothelial cells was not detectable with neutrophils from blood donors (1.11 +/- 1.09% 111in-release). Significantly increased 111in-release was apparent upon incubation with neutrophils of polytraumatized patients (5.76 +/- 1.28%). The data shows evidence of in vivo preactivation of neutrophils of polytraumatized patients, and supports the hypothesis that endothelial cells play an active role in neutrophil-endothelial cell interactions by modulating production of oxygen-derived metabolites.