Walnut extract inhibits LPS-induced activation of BV-2 microglia via internalization of TLR4: possible involvement of phospholipase D2.
Walnuts are a rich source of essential fatty acids, including the polyunsaturated fatty acids alpha-linolenic acid and linoleic acid. Essential fatty acids have been shown to modulate a number of cellular processes in the brain, including the activation state of microglia. Microglial activation can result in the generation of cytotoxic intermediates and is associated with a variety of age-related and neurodegenerative conditions. In vitro, microglial activation can be induced with the bacterial cell wall component lipopolysaccharide (LPS). In the present study, we generated a methanolic extract of English walnuts (Juglans regia) and examined the effects of walnut extract exposure on LPS-induced activation in BV-2 microglial cells. When cells were treated with walnut extract prior to LPS stimulation, production of nitric oxide and expression of inducible nitric oxide synthase were attenuated. Walnut extract also induced a decrease in tumor necrosis-alpha (TNFalpha) production. We further found that walnut extract induced internalization of the LPS receptor, toll-like receptor 4, and that the anti-inflammatory effects of walnut were dependent on functional activation of phospholipase D2. These studies represent the first to describe the anti-inflammatory effects of walnuts in microglia, which could lead to nutritional interventions in the prevention and treatment of neurodegeneration.
Willis
Lauren M
LM
USDA-ARS, Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
Bielinski
Donna F
DF
Fisher
Derek R
DR
Matthan
Nirupa R
NR
Joseph
James A
JA
D020001:1-Butanol / Q000494:pharmacology; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000494:pharmacology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005227:Fatty Acids / Q000032:analysis; D031324:Juglans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D017628:Microglia / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D009754:Nuts; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D051197:Toll-Like Receptor 4 / Q000187:drug effects* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D000893:Anti-Inflammatory Agents; D004791:Enzyme Inhibitors; D005227:Fatty Acids; D008070:Lipopolysaccharides; D010936:Plant Extracts; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D020001:1-Butanol; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C105606:phospholipase D2; D010739:Phospholipase D