Tumor necrosis factor alpha regulates in vivo intrapulmonary expression of ICAM-1

Abstract

Lung injury following deposition of IgG immune complexes is neutrophil-dependent and requires both tumor necrosis factor alpha (TNF alpha) and CD18. In the current studies, we have evaluated the relationship between TNF alpha and expression of intracellular adhesion molecule-1 (ICAM-1) in vitro and in vivo. In both rat pulmonary artery endothelial cells and human umbilical vein endothelial cells, TNF alpha induced an early (within 60 minutes) increase in ICAM-1 expression, followed by a peak at 6 to 8 hours, with relatively stable expression at 24 hours. Expression of E-selectin did not show the early phase (within 60 minutes) of up-regulation, peaked at 4 hours, and then declined thereafter. Using a radioimmunochemical assay in vivo, it was demonstrated that intrapulmonary deposition of IgG immune complexes caused a progressive increase in ICAM-1 expression in lung over an 8-hour period. In animals pretreated with antibody to TNF alpha, the intrapulmonary expression of ICAM-1 was significantly reduced. These results were confirmed by immunoperoxidase analysis of lung tissue. It was also shown that airway instillation of TNF alpha caused up-regulation of ICAM-1 in lung. These data support the concept that deposition of IgG immune complexes in lung induces intrapulmonary up-regulation of ICAM-1 in a manner that is TNF alpha-dependent.