Decreasing plasma endothelin-1 and unchanged plasma neopterin during folate supplementation in hyperhomocysteinemia

Abstract

Background: Hyperhomocysteinemia is a risk factor for atherosclerosis and venous thrombosis, probably exerting its effects through endothelial function. Homocysteine levels are lowered by folate supplementation, and such treatment improves endothelial function. However, whether folate supplementation decreases vascular risk and improves survival is unknown. The aim of this study was to evaluate endothelial function and mononuclear leukocyte inflammatory activity during homocysteine lowering in patients with hyperhomocysteinemia and vascular disease.

Methods: Endothelial function assessed as plasma (p-)endothelin(ET)-1 and intraplatelet cGMP and cAMP, and mononuclear leukocyte inflammatory activity, assessed as p-neopterin were studied during homocysteine lowering in 50 patients with hyperhomocysteinemia and vascular disease, randomized to folate supplementation or no treatment for 3 months.

Results: P-homocysteine decreased during the 3 months not only in patients on folate supplementation (from 27 [21-52] to 14 [8-41] micromol/l; p<0.001), but also in the untreated group (from 23 [20-35] to 19 [4-31] micromol/l; p<0.001). P-ET-1 decreased during folate supplementation (from 5.7 [2.7-11.6] to 4.1 [1.8-9.0] pg/ml; p<0.01), but was unchanged in the untreated group 4.1 [2.0-9.5] pg/ml and 4.5 [2.7-7.1] pg/ml). P-neopterin was unchanged in patients on folate supplementation (9.7 [5.1-54.4] and 7.6 [5.7-73.0] nmol/l), but increased in the untreated group (from 8.2 [4.7-19.5] to 8.6 [4.6-24.6] nmol/l; p<0.05). Intraplatelet cGMP decreased in patients on folate supplementation (from 0.86 [0.21-2.00] platelets to 0.56 [0.17-1.42] pmol/10(9) platelets; p<0.05), but was unchanged in the untreated group. No significant differences concerning intraplatelet cAMP occurred in either group.

Conclusions: Folate supplementation in hyperhomocysteinemia is associated with decreasing levels of both ET-1 and intraplatelet cGMP, and the absence of an increase in the levels of the inflammatory mediator neopterin.