Asbestos exposure upregulates the adhesion of pleural leukocytes to pleural mesothelial cells via VCAM-1

This study was designed to assess the effects of in vitro and in vivo asbestos exposure on the adhesion of rad pleural leukocytes (RPLs) labeled with the fluorochrome calcein AM to rat pleural mesothelial cells (RPMCs). Exposure of RPMCs for 24 h to either crocidolite or chrysotile fibers (1.25-10 mu g/cm(2)) increased the adhesion of RPLs to RPMCs in a dose-dependent fashion, an effect; that was potentiated by interleukin-lp. These findings were not observed with nonfibrogenic carbonyl iron particles. Crocidolite and chrysotile plus interleukin-1 beta also upregulated vascular cell adhesion molecule-1 mRNA and protein expression in RPMCs, and the binding of RPL to asbestos-treated RPMCs was abrogated by antivascular cell adhesion molecule-1 antibody. PRLs exposed by intermittent inhalation to crocidolite for 2 wk manifested significantly greater binding to RPMCs than did RPLs from sham-exposed animals. The ability of asbestos fibers to upregulate RPL adhesion to RPMCs may play a role in the induction and/or potentiation of asbestos-induced pleural injury.