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The relation between plasma cysteine, plasma homocysteine and coronary atherosclerosis
W E van den Brandhof1, K Haks, E G Schouten
1Division of Human Nutrition and Epidemiology, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Insights
Elevated plasma cysteine (tCys) levels were found in severe coronary atherosclerosis patients, but this association was confounded. Unlike homocysteine (tHcy), cysteine is not an independent risk factor for atherosclerosis.
Area of Science:
- Cardiovascular Disease Research
- Biomarker Analysis
- Atherosclerosis Etiology
Background:
- Elevated plasma total homocysteine (tHcy) is linked to cardiovascular disease risk.
- Limited research exists on plasma total cysteine (tCys) and cardiovascular disease risk.
Purpose of the Study:
- To compare plasma tCys and tHcy levels in subjects with and without severe coronary atherosclerosis.
- To determine if plasma tCys is an independent risk factor for coronary atherosclerosis.
Main Methods:
- A case-control study comparing plasma tCys and tHcy levels.
- Cases (n=131) had severe coronary atherosclerosis; controls (n=88, n=101) did not.
- Statistical analysis included odds ratios and multivariate adjustments.
Main Results:
- Cases showed significantly higher mean plasma tCys levels than controls.
- The unadjusted odds ratio for upper vs. bottom tCys tertile was 2.5.
- Multivariate adjusted odds ratio for tCys was 1.0, while for tHcy it was 1.4.
Conclusions:
- Plasma tCys is not an independent risk factor for coronary atherosclerosis.
- Plasma tHcy remains a significant independent risk factor.
- Cysteine's role in atherosclerosis requires further investigation beyond its association with homocysteine.
Abstract:
Several studies have reported that elevated plasma levels of total homocysteine (tHcy) are related to an increased risk of cardiovascular disease. Only a few studies have looked at the effect of cysteine, another amino thiol, on cardiovascular disease risk. Therefore, in the present case-control study we compared plasma total cysteine (tCys) levels and plasma tHcy levels among subjects with severe coronary atherosclerosis (cases, n=131), subjects without severe coronary atherosclerosis (coronary controls, n=88) and healthy subjects (population-based controls, n=101). Cases were defined as those having > or =90% occlusion in one and > or =40% occlusion in a second coronary artery, while coronary controls had a maximum of 50% occlusion in only one coronary artery. Both males and females, aged 26--64 years were studied. We have previously reported that plasma tHcy is an independent risk factor for coronary atherosclerosis in this study population. In the present analysis, we found that cases had statistically significant higher mean plasma tCys levels than coronary controls and population-based controls (295.8+/-40.2, 279.0+/-35.5 and 282.6+/-32.4 micromol/l, respectively). The odds ratio (OR) of coronary atherosclerosis for the upper tertile of tCys compared with the bottom tertile was 2.5 (95% confidence interval (CI), 1.4--4.3). However, the association between tCys and coronary atherosclerosis was confounded to a great extent by risk factors (OR, 1.0; 95% CI, 0.5--2.0). The multivariate adjusted OR of coronary atherosclerosis per 1 S.D. increase in plasma tCys was 1.0 (95% CI, 0.8--1.3). The corresponding OR per 1 S.D. increase in plasma tHcy was 1.4 (95% CI, 1.1--1.8). We conclude that plasma tCys, unlike plasma tHcy, is not an independent risk factor for atherosclerosis.