Activation of kainate receptors sensitizes oligodendrocytes to complement attack.
Glutamate excitotoxicity and complement attack have both been implicated separately in the generation of tissue damage in multiple sclerosis and in its animal model, experimental autoimmune encephalomyelitis. Here, we investigated whether glutamate receptor activation sensitizes oligodendrocytes to complement attack. We found that a brief incubation with glutamate followed by exposure to complement was lethal to oligodendrocytes in vitro and in freshly isolated optic nerves. Complement toxicity was induced by activation of kainate but not of AMPA receptors and was abolished by removing calcium from the medium during glutamate priming. Dose-response studies showed that sensitization to complement attack is induced by two distinct kainate receptor populations displaying high and low affinities for glutamate. Oligodendrocyte death by complement required the formation of the membrane attack complex, which in turn increased membrane conductance and induced calcium overload and mitochondrial depolarization as well as a rise in the level of reactive oxygen species. Treatment with the antioxidant Trolox and inhibition of poly(ADP-ribose) polymerase-1, but not of caspases, protected oligodendrocytes against damage induced by complement. These findings indicate that glutamate sensitization of oligodendrocytes to complement attack may contribute to white matter damage in acute and chronic neurological disorders.
Departamento de Neurociencias, Universidad del País Vasco, E-48940 Leioa, Vizcaya, Spain.
Elena
E
Alberdi
María Victoria
MV
Sánchez-Gómez
Iratxe
I
Torre
María
M
Domercq
Alberto
A
Pérez-Samartín
Fernando
F
Pérez-Cerdá
Carlos
C
Matute
D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000276:immunology; D002462:Cell Membrane / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D003165:Complement System Proteins / Q000276:immunology* / Q000378:metabolism; D020278:Demyelinating Autoimmune Diseases, CNS / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D009498:Neurotoxins / Q000378:metabolism; D009836:Oligodendroglia / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D009900:Optic Nerve / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000276:immunology; D018408:Patch-Clamp Techniques; D011062:Polynucleotide Adenylyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018092:Kainic Acid Receptors / Q000819:agonists / Q000378:metabolism*
D000975:Antioxidants; D002118:Calcium; D003165:Complement System Proteins; D018698:Glutamic Acid; D009498:Neurotoxins; D011062:Polynucleotide Adenylyltransferase; D018092:Kainic Acid Receptors