Protective effects of an anti-inflammatory cytokine, interleukin-4, on motoneuron toxicity induced by activated microglia.
Microglia-mediated cytotoxicity has been implicated in models of neurodegenerative diseases, such as amyotrophic lateral sclerosis, Parkinson's disease and Alzheimer's disease, but few studies have documented how neuroprotective signals might mitigate such cytotoxicity. To explore the neuroprotective mechanism of anti-inflammatory cytokines, we applied interleukin-4 (IL-4) to primary microglial cultures activated by lipopolysaccharide as well as to activated microglia cocultured with primary motoneurons. lipopolysaccharide increased nitric oxide and superoxide (O(2) (.-)) and decreased insulin-like growth factor-1 (IGF-1) release from microglial cultures, and induced motoneuron injury in microglia-motoneuron cocultures. However, lipopolysaccharide had minimal effects on isolated motoneuron cultures. IL-4 interaction with microglial IL-4 receptors suppressed and nitric oxide release, and lessened lipopolysaccharide-induced microglia-mediated motoneuron injury. The extent of nitric oxide suppression correlated directly with the extent of motoneuron survival. Although IL-4 enhanced release of free IGF-1 from microglia in the absence of lipopolysaccharide, it did not enhance free IGF-1 release in the presence of lipopolysaccharide. These data suggest that IL-4 may provide a significant immunomodulatory signal which can protect against microglia-mediated neurotoxicity by suppressing the production and release of free radicals.
Zhao
Weihua
W
Department of Neurology, Methodist Neurological Institute, The Methodist Hospital, Houston, Texas 77030, USA.
Xie
Wenjie
W
Xiao
Qin
Q
Beers
David R
DR
Appel
Stanley H
SH
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000276:immunology / Q000494:pharmacology*; D002450:Cell Communication / Q000187:drug effects / Q000276:immunology; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D002478:Cells, Cultured; D018920:Coculture Techniques; D019610:Cytoprotection / Q000187:drug effects / Q000276:immunology; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D018836:Inflammation Mediators / Q000037:antagonists & inhibitors; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D015847:Interleukin-4 / Q000276:immunology / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors; D017628:Microglia / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D009046:Motor Neurons / Q000187:drug effects* / Q000276:immunology; D009410:Nerve Degeneration / Q000188:drug therapy* / Q000503:physiopathology / Q000517:prevention & control; D019636:Neurodegenerative Diseases / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control; D018696:Neuroprotective Agents / Q000276:immunology / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D019948:Receptors, Interleukin-4 / Q000819:agonists / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects* / Q000276:immunology / Q000503:physiopathology; D013481:Superoxides / Q000378:metabolism
D000893:Anti-Inflammatory Agents; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D018696:Neuroprotective Agents; D019948:Receptors, Interleukin-4; D013481:Superoxides; D015847:Interleukin-4; D009569:Nitric Oxide; D007334:Insulin-Like Growth Factor I