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ARDS (acute respiratory distress syndrome) can be associated with septic shock and multiple organ failure caused by an uncontrolled systemic inflammatory response to Gram-negative bacterial infection. While in animal models the key role of the endothelial adhesion molecules ICAM-1, E-selectin, and VCAM in ARDS has been extensively studied, there are scarcely any corresponding pathomorphological studies of human lung tissue. Hence, little is known about whether there is a comparable, or even heterogeneous, expression pattern of these molecules in the human pulmonary vasculature. This study was therefore undertaken to investigate the immunohistochemical expression of the constitutively expressed PECAM (CD31) and the inducible molecules ICAM-1, E-selectin, and VCAM in ARDS lungs from patients who had died in septic shock induced by Gram-negative bacteria. While in all specimens (ARDS and normal lungs) there was homogeneous strong expression of PECAM in all vessels, ICAM-1 was clearly up-regulated in ARDS lungs. E-selectin and VCAM were not expressed by endothelial cells (ECs) in normal lungs, but in ARDS lungs there was strong expression of both molecules in larger vessels, while in the capillaries there was only mosaic-like weak expression of a few ECs. This immunohistochemical investigation demonstrates the induction and up-regulation of adhesion molecules in human ARDS lungs, comparable to that described in animal models. There is also markedly heterogeneous expression of E-selectin and VCAM, indicating toporegional differences in the function of pulmonary ECs.

Endothelial monolayer cell cultures have been used to study pathomechanisms under standardized in vitro conditions. These results can only be regarded as valid as long as phenomena studied in vitro are comparable to findings in situ, e.g. in organ culture. The aim of the present study was to examine the reliability and comparability between human umbilical vein endothelial cells (HUVEC) in a monolayer cell culture model and endothelial cells (EC) in organ culture, as well as in the native umbilical cord. Our results prove the reliability of HUVEC as a model for standardized investigations of EC. The differences found suggest that gradual differences in antigen expression in vitro and in situ become apparent by comparing in situ and in vitro investigations.