Induction of Matrix Metalloproteinases-14 and -2 by Cyclical Mechanical Stretch is Mediated by Tumor Necrosis Factor-alpha in Cultured Human Umbilical Vein Endothelial Cells

Objective: Mechanical forces have profound effects on endothelial cells. This study was undertaken to examine the hypothesis that tumor necrosis factor-alpha (TNF-alpha) is a potential mediator of stretch-induced effects on matrix metalloproteinase (MMP).

Methods: Human umbilical vein endothelial cells (HUVECs) grown on a flexible membrane base were stretched by vacuum to 20% of maximum elongation, at 60 cycles/min. We used the TNF-alpha monoclonal antibody and c-Jun N-terminal kinase (JNK) inhibitor, SP600125, to investigate the cyclical stretch-induced expression of MMP-14 and -2 in cultured HUVECs.

Results: Cyclical mechanical stretch significantly increased protein synthesis and mRNA expression for MMP-14 and -2 from 2 to 24 h. The increased MMP-14 and-2 proteins after stretch were completely blocked after the addition of TNF-alpha monoclonal antibody (5 microg/ml) or SP600125 (20 microM) 30 min before stretch. By zymography, MMP-2 expression was induced by cyclical stretch and was attenuated by TNF-alpha monoclonal antibody and SP600125. Cyclical stretch increased the immunohistochemical labeling of MMP-14 and -2 and significantly increased release of TNF-alpha into the culture media from 120+/-2 to 331+/-2 pg/ml (P<0.001) after stretch for 12 h. Cyclical stretch increased and SP600125 decreased the phosphorylated JNK. Gel-shifting assay showed that DNA-protein binding activity of AP-1 increased after cyclical stretch and TNF-alpha monoclonal antibody and SP600125 abolished the binding activity induced by cyclical stretch.

Conclusion: These findings indicate that cyclical stretch augments TNF-alpha production and MMP genes expression in HUVECs. TNF-alpha mediates the stretch-induced MMP genes expression, at least in part, through the JNK pathway.