INHIBITION OF TUMOR-NECROSIS-FACTOR-ALPHA (TNF-ALPHA) AND INTERLEUKIN-1-BETA (IL-1-BETA) SECRETION BUT NOT IL-6 FROM ACTIVATED HUMAN PERIPHERAL-BLOOD MONOCYTES BY A NEW SYNTHETIC DEMETHYLPODOPHYLLOTOXIN DERIVATIVE

A newly synthesized demethylpodophyllotoxin derivative, 4-O-butanoyl-4 '-demethylpodophyllotoxin (BDPT) or BN58705, has recently been shown t o exert a potent cytotoxic activity in vitro against a variety of drug -resistant human tumor cell lines. The effect of this agent on effecto r cells of the immune system, however, has not been examined. The pres ent study investigated the effect of BDPT on the response of activated human peripheral blood derived monocytes (PBM) to secrete cytokines. Activation of PBM overnight with LPS, IFN-gamma, or PMA resulted in se cretion into the supernatant of TNF-alpha, IL-1 beta, IL-6, and IL-8 a s assessed by ELISA. The addition of BDPT to the stimulated cultures r esulted in significant inhibition of TNF-alpha and IL-1 beta secretion , whereas the secretion of IL-6 and IL-8 was not affected. The selecti ve inhibition of TNF-alpha and IL-1 beta secretion by BDPT-treated PBM was observed with all three stimuli tested. The inhibitory effect med iated by BDPT was concentration dependent and was optimal at 6-20 mu M . Time kinetic analysis indicated that the inhibition of secretion was rapid and detected as soon as 2 hr following stimulation of the PBM a nd lasted for as long as 24 hr. A comparison was made between BDPT and pentoxyfilline, a xanthine-derived phosphodisterase inhibitor that wa s reported to inhibit TNF-alpha and IL-1 beta secretion by PBM. Both B DPT and PTX showed similar time kinetics and patterns of inhibition. H owever, the concentration used by BDPT to achieve optimal inhibition o f secretion was 10- to 20-fold less than that needed by PTX. The selec tive inhibition of TNF-alpha secretion by BDPT and PTX was corroborate d by inhibition of TNF-alpha mRNA but not IL-6 mRNA as assessed by RT- PCR analysis. These studies demonstrate that the antitumor cytotoxic c ompound BDPT is also an immunomodulatory agent that can inhibit select ively TNF-alpha and IL-1 beta secretion by PBM. Further, the low toxic ity and low concentrations of BDPT needed for optimal inhibition sugge st that BDPT may have potential in its therapeutic application in dise ases that are mediated by TNF-alpha and IL-1 like septic shock, inflam matory responses, and infections.