Paraoxonase 1(PON1) is an HDL-associated
protein, which metabolizes inflammatory, oxidized
lipids associated with
atherosclerotic plaque development. Because oxidized
lipid mediators have also been implicated in the pathogenesis of
rheumatoid arthritis (RA), we evaluated the role of PON1 in murine inflammatory
arthritis. K/BxN serum transfer (STIA) or
collagen antibody transfer (CAIA) was used for
arthritis induction in B6 mice homozygous for the PON1 human transgene [PON1Tg], PON1 knock-out mice [PON1KO], and wild type littermate control mice [WT]. Experiments were also performed in K/BxN mice with chronic
arthritis, and in RA patients and healthy controls.
Arthritis activity in K/BxN mice was associated with a marked
dyslipidemia, lower PON1 activity and higher bioactive
lipid mediators (BLM), as well as a dysregulated hepatic
lipid gene expression profile. Higher serum PON1 activity correlated with lower BLM and lower
arthritis activity in both K/BxN mice and RA patients. Overexpression of the human PON1 transgene was associated with reduced inflammatory
arthritis, which correlated strongly with higher circulating PON1 activity, upregulation of the hepatic
glutathione pathway, and reduction of circulating BLM. These results implicate PON1 as a potential novel therapeutic target for
joint disease in RA with potential for vascular benefit, which warrants further investigation.