Remodeling in vein expresses arterial phenotype in hyperhomocysteinemia.

Accumulating evidences suggest that homocysteine, a non-protein amino acid, is involved in vessel remodeling and blood flow at elevated level, although the exact mechanism is unclear. Here we hypothesized that homocysteine affects vein in such a way that vein develops arterial phenotype. We tested our hypothesis employing wild type (WT, C57BL/6J) and CBS+/- (cystathionine ß-synthase heterozygote, a genetic model of hyperhomocysteinemia) supplemented with or without folic acid (FA, a homocysteine lowering agent). Vena cava blood flow was measured by ultrasound transonic flow probe. Tissue collagen and elastin were detected by histochemistry. Super oxide was detected by dihydroethidium (DHE) staining. Expressions of MMP-2, -9, -12, TIMP -2,-4, were measured by Western blot. MMP-13, TIMP-1, -3, and vein and aortic markers, EphB4 and EphrinB2, respectively were measured by RT-PCR. The results indicated relatively low blood flow and significant increase of collagen/elastin ratio in the CBS+/- mice compared to WT. Although FA treatment did not alter blood flow in CBS+/- mice, the collagen/elastin ratio was normalized. A relatively increased content of super oxide and gelatinase activity was observed in CBS+/- vena cava vs WT and normalized by FA treatment. Western blot analyses showed significant increase in MMP-9,-12 and decrease in TIMP-2, -4 expressions. Expressions of MMP-13, TIMP-1 and -3, Ephrin B2 were increased, whereas EphB4 was decreased with reverse change in FA treatment, with no change in MMP-13 and TIMP-1. We conclude that chronic HHcy causes vascular remodeling that expresses arterial phenotype in vein.