The role of Bcl-xL and nuclear factor-kappaB in the effect of taxol on the viability of dendritic cells

Taxol has been used effectively in cancer therapies. Our previous study demonstrated that taxol induced altered maturation and improved viability of dendritic cells (DCs). However, the effects of taxol on DC viability have not been fully elucidated. In the present study, flow cytometric analyses revealed that taxol treatment significantly increased the number of viable DCs and the expression levels of a representative anti-apoptotic protein Bcl-xL. Furthermore, mobilization of the p65 subunit of nuclear factor-kappaB (NF-kappaB) from the cytosol to the nucleus in DCs was observed by confocal microscopy. An inhibition assay using N-p-tosyl-L-phenylalanine chloromethyl ketone confirmed that NF-kappaB was intimately involved in the effects of taxol on DC viability. In addition, we investigated the mechanisms of taxol enhancement of DC viability. Since taxol is a popular anticancer agent used in clinic, this study may provide a rationale for the use of taxol in DC immunotherapy to treat cancer patients. Taken together, these results confirm that taxol increases DC viability, and this information may provide new insights for new clinical applications of both taxol and DCs.

Modulation of tryptase and histamine release from human lung mast cells by protease inhibitors.

Inhibition of IgE dependent histamine release from human mast cells by protease inhibitors has been observed in skin, tonsil and synovial tissues. However, little is known about the actions of protease inhibitors on tryptase release from human lung mast cells. We therefore examined the ability of protease inhibitors to modulate tryptase and histamine release from human lung mast cells. IgE dependent tryptase release from dispersed lung mast cells was inhibited to a maximum of approximately 53.8% and 44.5% by N-a-tosyl-L-lysine chloromethyl ketone (TLCK) and N-p-Tosyl-L-phenylalanine chloromethyl ketone (TPCK), respectively. A similar degree of inhibition of calcium ionophore A23187 (CI) induced tryptase release was also observed with these two inhibitors. Preincubation of TLCK or TPCK with the mast cells at 37 degrees C for 20 minutes before addition of anti-IgE or CI did not improve their ability to inhibit anti-IgE and CI induced tryptase release. At a concentration of 10 microg/ml, protamine inhibited anti-IgE or CI induced tryptase release; but at 100 microg/ml, it increased anti-IgE and CI induced release of tryptase from lung mast cells. A concentration dependent inhibition of anti-IgE and CI induced release of histamine from lung mast cells was also observed with TLCK, TPCK and protamine. The maximum inhibition of anti-IgE induced histamine release was approximately 40.7%, 40.2% and 33.4% with TLCK, TPCK and protamine, respectively. At the concentrations tested, TLCK and TPCK by themselves did not stimulate tryptase and histamine release from lung mast cells. A specific inhibitor of aminopeptidase, amastatin, had no effect on anti-IgE induced tryptase and histamine release and was used as control. In conclusion, it was demonstrated that protease inhibitors are able to inhibit IgE dependent tryptase and histamine release from human lung mast cells, which suggested that they could be developed to a novel class of anti-inflammatory drugs to treat allergic conditions in man.