Mononuclear cell conditioned medium enhances bronchial epithelial cell migration but inhibits attachment to fibronectin

Abstract

The attachment and migration of bronchial epithelial cells are important features in re-epithelialization after tissue injury. We hypothesized that inflammatory cytokines might alter bronchial epithelial cell attachment and migration. To test this hypothesis, we evaluated the effects of mononuclear cell conditioned medium (MNCCM) on attachment and migration of bronchial epithelial cells to fibronectin in vitro. MNCCM was prepared from bovine blood mononuclear cells that were stimulated with concanavalin A. MNCCM stimulated bronchial epithelial cell migration and spreading. Sephadex G-75 column chromatography of MNCCM found two peaks of migration-stimulatory activity. Activity in the higher molecular weight peak was partially inhibited by anti-tumor necrosis factor- α antibodies. Activity in the low-molecular-weight peak was lipid-extractable, suggesting the possibility that the activity was an arachidonate metabolite. We evaluated the effects of protein kinase C (PKC) inhibitors on enhancement of bronchial epithelial cell migration by MNCCM under the hypothesis that stimulated bronchial epithelial cell migration by MNCCM was elicited through PKC-dependent signaling pathways. PKC inhibitors, calphostin and H-7, inhibited the effect of MNCCM on bronchial epithelial cell migration. In addition, MNCCM stimulated PKC translocation and activity in these cells. Thus mononuclear cells produce inflammatory cytokines with important effects on bronchial epithelial cell migration and spreading. The stimulatory effect may be mediated in part through PKC signaling pathways.