title: Vimentin is secreted by activated macrophages.
abstract: Vimentin is a widely expressed intermediate filament protein thought to be involved mainly in structural processes, such as wound healing. We now demonstrate that activated human macrophages secrete vimentin into the extracellular space. The maturation of blood-derived monocytes into macrophages involves several signalling pathways. We show that secretion of vimentin, which is phosphorylated at serine and threonine residues, is enhanced by the phosphatase inhibitor okadaic acid and blocked by the specific protein kinase C inhibitor GO6983. These findings are consistent with previous observations that phosphorylation of vimentin affects its intracellular localization and that vimentin is a substrate for protein kinase C (PKC). We also show that the anti-inflammatory cytokine interleukin-10 (IL-10), which inhibits PKC activity, blocks secretion of vimentin. In contrast, the pro-inflammatory cytokine tumour necrosis factor alpha (TNF-alpha) can trigger secretion of vimentin. Finally, we found that extracellular vimentin is involved in bacterial killing and the generation of oxidative metabolites, two important functions of activated macrophages. These data establish that vimentin is secreted by macrophages in response to pro-inflammatory signalling pathways and is probably involved in immune function.
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases, University of Michigan Medical Center, Ann Arbor, MI 48109-0640, USA.
authors.forename: Nirit
authors.initials: N
authors.lastname: Mor-Vaknin
authors.forename: Antonello
authors.initials: A
authors.lastname: Punturieri
authors.forename: Kajal
authors.initials: K
authors.lastname: Sitwala
authors.forename: David M
authors.initials: DM
authors.lastname: Markovitz
mesh_terms: D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D016753:Interleukin-10 / Q000494:pharmacology; D007700:Kinetics; D008262:Macrophage Activation / Q000502:physiology*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology; D019319:Okadaic Acid / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D015398:Signal Transduction; D014746:Vimentin / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D014746:Vimentin; D016753:Interleukin-10; D019319:Okadaic Acid; D011493:Protein Kinase C