Oxidized phosphatidylcholine is a marker for neuroinflammation in multiple sclerosis brain

Abstract Multiple sclerosis (MS) is a common autoimmune neurodegenerative disease of unknown cause, which results in inflammation and plaques of demyelination in brain and eventual axonal degeneration. We report the novel presence of oxidized phosphatidylcholine [1‐palmitoyl‐2‐(5′‐oxo)valeryl‐sn‐glycero‐3‐phosphorylcholine (POVPC)], a lipid associated with inflammatory diseases such as atherosclerosis and lung disease, in the brain of MS patients. The OxPC epitope was detected by Western blotting with the E06 monoclonal antibody. E06‐positive lipid was present in the highest amounts in MS plaques, which also showed evidence of low‐molecular‐weight (15‐kDa) OxPC‐modified protein. E06 reactivity did not change with post‐mortem interval, and E06‐positive lipids were largely absent from control tissue. We then used a second monoclonal antibody (AB1‐2, which recognizes the E06/T15 idiotype and therefore detects the presence of antibody to OxPC) to show that MS brain samples were strongly positive for the 50‐kDa antibody heavy chain. We also showed that isoelectric focussing of the oligoclonal IgG characteristic of MS revealed some immunoglobulin bands that Western blotted with the AB1‐2 antibody. Spinal cords from mice induced to undergo experimental allergic encephalomyelitis (EAE) also showed strong AB1‐2 reactivity by both immunocytochemistry and Western blot analysis. We therefore conclude that we can detect both OxPC and 15‐kDa protein modified by OxPC and the antibody to the antibody to OxPC (antiidiotype) in pathological tissue and suggest that this could play a role in the progression of MS. © 2007 Wiley‐Liss, Inc.