gms | German Medical Science

Cysteine proteases cathepsins and caspases are known as important factors in the pathogenesis of vascular damage, hence increased activity of these proteases causes apoptosis. Previously we have shown that Interferon-gamma (IFNgamma) is up-regulated in the rat model of aortic aneurysm. In order to understand the influence of IFNgamma on apoptotic processes in the vasculature, we investigated endothelial cells (EC) using analysis of the protein expression of apoptotic markers, cathepsins and the cysteine protease inhibitor kininogen.

Endothelial cells were isolated from aortas of male Wistar rats via the explant method for primary culture. After stimulation with IFNgamma for 24 to 72 hours followed by growth factor withdrawal for apoptosis induction, cells were lysed and proteins were isolated for Western Blot analysis of cathepsin B, D and L, caspase 3 and FasL as well as of kininogen in either protein extract or medium.

We have found, that after apoptosis induction cathepsin B (procathepsin B and active forms) was up-regulated (2-fold) in cells and medium. Protein levels of cathepsin L showed no significant changes. No expression of cathepsin D was found. Procaspase-3 expression was up-regulated and active caspase-3 forms were detected only after 72 hours stimulation. Up-regulated levels of FasL active forms were also detected. Analysis of kininogen showed down-regulation (2-fold) of the two-chain high molecular weight form in protein extract and medium as well.

Therefore IFNgamma stimulation of EC is associated with increased expression of cathepsin B, caspase-3 and FasL and triggers the apoptotic process. Furthermore altered excretion of cysteine proteases and its inhibitor kininogen may have an influence on matrix degeneration. Enhanced expression of active FasL may contribute to apoptosis in other cell types like vascular smooth muscle cells