| Abstract: | Although elevated levels of homocysteine (Hcy) known as hyperhomocysteinemia (HHcy) are associated with increased inflammation and vascular remodeling, the mechanism of Hcy-mediated inflammation and vascular remodeling is unclear. The matrix metalloproteinases (MMPs) and adhesion molecules play an important role in vascular remodeling. We hypothesized that HHcy induces inflammation by increasing adhesion molecules and matrix protein expression. Endothelial cells were supplemented with high methionine, and Hcy accumulation was measured by HPLC. Nitric oxide (NO) bioavailability was detected by a NO probe. The protein expression was measured by Western blot analysis. MMP-9 activity was detected by gelatin-gel zymography. We demonstrated that methionine supplement promoted upregulation of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) through increased Hcy accumulation. In addition, increased synthesis of collagen type-1 was also observed. MMP-9 gene expression and protein activity were increased in methionine supplement groups. 3-Deazaadenosine (DZA), an adenosine analogue, prevented high methionine-induced ICAM-1 and VCAM-1 expression and collagen type-1 synthesis. Transfection of endothelial cells with cystathionine-β-synthase (CBS) gene construct, which converts Hcy to cystathionine, reduced Hcy accumulation in high methionine-fed cells. CBS gene transfection reduced the inflammatory response, as evident by attenuated ICAM-1 and VCAM-1 expression. Furthermore, collagen type-1 expression and MMP-9 activity were dramatically attenuated with CBS gene transfection. These results suggested that methionine supplement increased Hcy accumulation, which was associated with inflammatory response and matrix remodeling such as collagen type-1 synthesis and MMP-9 activity. However, in vitro DZA and CBS gene therapy successfully treated the HHcy-induced inflammatory reaction in the methionine metabolism pathway. extracellular matrix; matrix metalloproteinase-9; intercellular cell adhesion molecule-1; vascular cell adhesion molecule-1; collagen type-1; hyperhomocysteinemia |
