Increased plasma levels of homocysteine and other thiol compounds in rheumatoid arthritis women

Objectives: Since moderate hyperhomocysteinemia is an independent risk fact or for vascular disease and physiological thiol compounds mediate Cu2+- and Fe3+-dependent low-density lipoprotein (LDL) oxidation, we have studied th e total plasma concentrations of thiol compounds including methionine as pr ecursor of homocysteine in rheumatoid arthritis patients, in which the high mortality found is associated with cardiovascular disease. Design and methods: Thirty-eight women with rheumatoid arthritis and 25 age -matched control women were studied. Plasma was used to measure thiol compo unds and amino acids by HPLC. Results: Rheumatoid arthritis patients showed significantly higher levels t han healthy controls of total plasma homocysteine (17.3 +/- 7.8 vs. 7.6 +/- 1.9; p < 0.001), cysteine (293 +/- 61 vs. 201 +/- 45; p < 0.001), cysteing lycine (32.7 +/- 8.3 vs. 22.3 +/- 4.7; p < 0.001) and methionine (25 +/- 9 vs. 18 +/- 3; p < 0.01), whereas total glutathione levels were not increase d (4.7 +/- 2.0 vs. 4.1 +/- 1.6). Conclusions: The increased levels of thiol compounds found in rheumatoid ar thritis patients may be implicated in the increased incidence of cardiovasc ular disease found in these patients by means of the toxic effect of homocy steine on endothelium and the increased susceptibility of LDL to oxidation by increased plasma amounts of thiol compounds such as cysteine. Copyright (C) 1999 The Canadian Society of Clinical Chemists.