Upregulation of I-CAM1 in response to beryllium exposure in small airway epithelial cells

Abstract

Chronic Beryllium Disease (CBD) is a delayed-type hypersensitivity immune reaction that leads to granuloma formation in the lungs and potentially severe loss of pulmonary function. Although the molecular mechanisms that mediate beryllium (Be)-stimulated granuloma formation are not well understood, cell adhesion molecules are likely to play a key role in the migration of immune cells to sites of inflammation. In this study, we examined the role of the cell adhesion molecule I-CAM1 in Be-stimulated small airway epithelial cells (SAECs). These epithelial cells line the airway and represent the first point of contact for inhaled foreign substances. We find that Be exposure specifically induced I-CAM1 expression on the cell surface of SAEC and release of soluble I-CAM1 into the extracellular medium. Furthermore, anti-I-CAM1 antibodies inhibited Be-stimulated adhesion of SAEC to the macrophage cell-line THP1, indicating that the Be-induced adhesive properties of SAEC are at least partly due to I-CAM1 expression. These studies support a model in which I-CAM1 cell adhesion functions may play a role in directing immune cells to the lung and activating a Be-specific immune response in Be hypersensitivity disease.