Comparison of normal protective anti-inflammatory high-density lipoproteins (HDLs) (a) to proinflammatory HDLs (b). Normal HDLs are rich in apolipoproteins (yellow ovals) and antioxidant enzymes (white squares). After exposure to pro-oxidants, oxidized lipids, and proteases, proinflammatory HDLs have less lipoprotein and some, such as the major transporter apolipoprotein A-1 (A-1 in the figure), are disabled by the addition of chlorine, nitrogen, and oxygen to protein moieties: A-1 can no longer stabilize paraoxonase-1 (PON1) so PON1 cannot exert its antioxidant enzyme activity. In addition, pro-oxidant acute-phase proteins are added to the particle (serum amyloid A [SAA] and ceruloplasmin) as are oxidized lipids. The figure is based on information in  and . apoJ, apolipoprotein J; CE, cholesterol ester; CE-OOH, cholesteryl linoleate hydroperoxide; GSH, glutathione; HPETE, hydroxyeicosatetraenoic acid; HPODE, hydroperoxy-octadecadienoic acid; LCAT, lecithin cholesterol acyltransferase; PAF-AH, platelet-activating acyl hydrolase.
Hahn et al. Arthritis Research & Therapy 2008 10:213 doi:10.1186/ar2471