A MODIFIED FORM OF LOW-DENSITY-LIPOPROTEIN WITH INCREASED ELECTRONEGATIVE CHARGE IS PRESENT IN RHEUMATOID-ARTHRITIS SYNOVIAL-FLUID

Reactive oxygen species (ROS) are pro-inflammatory factors in the path ogenesis of rheumatoid arthritis. During inflammation, the amount of l ow-density Lipoprotein (LDL) in the inflamed joint is increased. LDL i s known to be susceptible to oxidation by ROS. Oxidized LDL may serve as a mediator for joint damage, further exacerbating the inflammatory process. LDL isolated from synovial fluid and plasma from individual p atients (paired samples) with rheumatoid arthritis or osteoarthritis w as characterized by crossed immunoelectrophoresis. On analysis by this technique, synovial fluid LDL from most patients with rheumatoid arth ritis contained two peaks: one corresponding to normal plasma native L DL, and the other having an increased electrophoretic mobility associa ted with oxidized LDL. Paired plasma LDL samples contained native LDL alone, as did paired synovial fluid and plasma LDL from patients with osteoarthritis. Thus, in addition to native LDL, a second form of LDL was shown to be present in rheumatoid synovial fluid, which had proper ties consistent with those of oxidized LDL. Copyright (C) 1997 Elsevie r Science Inc.