title: Involvement of calcium signaling in the fibronectin-stimulated macrophage recognition of oxidatively damaged erythrocytes.
abstract: Macrophages recognize oxidatively damaged autologous erythrocytes, and cell surface fibronectin of macrophages enhances the recognition (Beppu et al., FEBS Lett. 295 (1991) 135-140). In the present study, mechanisms of enhanced macrophage recognition of oxidatively damaged erythrocytes by fibronectin were investigated. Monolayers of thioglycollate-induced mouse peritoneal macrophages with cell surface fibronectin recognized autologous erythrocytes oxidized with an iron catalyst ADP/Fe(3+). The macrophage recognition of the oxidized erythrocytes was inhibited partially by pretreatment of the macrophage monolayers with a Ca(2+) channel blocker (diltiazem), calmodulin inhibitors (W-7, trifluoperazine, chlorpromazine and dibucaine), an inhibitor of myosin light chain kinase (ML-9), a microfilament formation inhibitor (cytochalasin B), phospholipase A(2) inhibitors (4-bromophenacyl bromide, mepacrine) and cyclooxygenase inhibitors (indomethacin and aspirin). Monolayers of macrophages depleted of fibronectin by trypsinization lost the ability of recognizing oxidized erythrocytes, but acquired the ability when stimulated with a fibronectin-coated coverslip. The recognition of fibronectin-stimulated trypsinized macrophages was also inhibited by the above inhibitors. On treatment with Ca ionophore A23187, trypsinized macrophages acquired the ability to recognize oxidized erythrocytes. The recognition of Ca ionophore-stimulated trypsinized macrophages was inhibited by the above inhibitors except the Ca(2+) channel blocker. These results indicate that the Ca(2+) signaling including Ca(2+) influx, calmodulin activation and myosin light chain phosphorylation are involved in the fibronectin stimulation of the recognition of macrophages for oxidized erythrocytes. Involvement of microfilament formation and arachidonate cascade in the fibronectin stimulation was also suggested.
authors.affiliation: School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Beppu
authors.forename: M
authors.initials: M
authors.lastname: Azuma
authors.forename: N
authors.initials: N
authors.lastname: Maruyama
authors.forename: K
authors.initials: K
authors.lastname: Kikugawa
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000502:physiology*; D005353:Fibronectins; D017737:Macrophages, Peritoneal / Q000502:physiology*; D008297:Male; D051379:Mice; D018384:Oxidative Stress; D011956:Receptors, Cell Surface / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D005353:Fibronectins; D011956:Receptors, Cell Surface; C038340:lactoferrin receptors; D002118:Calcium