Methods: Endothelial cells (HUVEC) were stimulated by purified Pg-LPS for 24, 48 or 72 hours or infected with whole bacteria for 2 to 6 hours. Cell lysates were prepared to measure the enzymatic activity of cathepsin B as well as the amount of protein by Western blotting.
Results: Our results showed an increase of the enzymatic activity of cathepsin B during the time-course stimulation by Pg- LPS or infection with whole bacteria without modification of the rate of mRNA expression or protein concentration. Concerning regulation of the activity of cathepsin B, our data showed that the tyrosine-dephosphorylation form of the enzyme is associated with its activity in infected endothelial cells and not in cells only stimulated by purified Pg-LPS.
Conclusion: Our results evidenced that cathespin B is differentially regulated depending on bacterial virulence factors. These results contribute to explain deleterious action of Pg on endothelial cells.