Class A type II scavenger receptor mediates silica-induced apoptosis in Chinese hamster ovary cell line.
Macrophage scavenger receptors are known to bind endotoxins, oxidized low-density lipoproteins (Ox-LDL), and other proteins with clustered negative charges. Recent evidence indicates some particulates may also bind to the scavenger receptor and initiate apoptosis. In this study, chinese hamster ovary (CHO) cells stabily transfected with the murine class A type II scavenger receptor (SR-A II) were exposed to crystalline silica to examine the role of this receptor in apoptosis. In a 24-h culture, silica (250 microg/ml) induced significant cell injury (necrosis and apoptosis) in transfected cells (MSR II) but not in the control cells (KA-7). This effect was specific to silica, as a control particle titanium dioxide had no cytotoxic effects on the MSR II cells at equal particle mass concentrations. Furthermore, silica-induced apoptosis in the MSR II cells could be eliminated by preincubating the cells with SR-A II antagonists: polyinosinic acid or maleylated bovine serum albumin. This study further supports the hypothesis that the SR-A II is directly involved with silica toxicity and that certain scavenger receptor ligands may have an important role in regulating macrophage apoptosis.
Hamilton
R F
RF
Division of Pulmonary and Critical Care Medicine, University of Texas Houston Health Science Center, Houston, Texas 77030, USA.
de Villiers
W J
WJ
Holian
A
A
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D016466:CHO Cells / Q000187:drug effects / Q000473:pathology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D009336:Necrosis; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051116:Receptors, Scavenger; D051117:Scavenger Receptors, Class A; D012822:Silicon Dioxide / Q000633:toxicity*; D014025:Titanium / Q000633:toxicity; D014162:Transfection
D011971:Receptors, Immunologic; D051116:Receptors, Scavenger; D051117:Scavenger Receptors, Class A; C009495:titanium dioxide; D012822:Silicon Dioxide; D014025:Titanium