EFFECT OF PENTAMIDINE ON CYTOKINE (IL-1-BETA, TNF-ALPHA, IL-6) PRODUCTION BY HUMAN ALVEOLAR MACROPHAGES IN-VITRO

Pentamidine (Pe) is an aromatic diamidine drug used clinically to trea t Pneumocystis carinii pneumonia by aerosol inhalation. Nothing has be en reported about the effects of this drug on human alveolar macrophag e (AM) properties. In this study AM were exposed in vitro to various c oncentrations of Pe (10(-4)-10(-6) M) alone or in combination with bac terial endotoxin (LPS). Supernatants were collected at 3, 6, and 24 b and assayed for secreted IL-1beta, IL-6, and TNFalpha. While the drug did not induce release of these cytokines, LPS-induced secretion of al l three cytokines was inhibited by Pe in a dose-dependent manner. At t he most effective Pe dose, 10(-5) M, AM viability (as determined by tr ypan blue dye exclusion) was reduced by 14% at 24 h, while no effect o n viability was seen at lower concentrations. mRNA expression of all t hree cytokines was examined by PCR and Northern analysis to establish if the decrease in cytokine secretion was determined on a pre- or post -translational level. Reduced steady-state mRNA levels were found as e arly as 3 b after LPS stimulation, with Pe concentrations correspondin g to those that decreased cytokine secretion. At the later time points , Pe also inhibited beta-actin, ornithine decarboxylase, and GAPDH mRN A expression, indicating that pentamidine bad a general toxic effect o n mRNA transcription in the macrophages. It is concluded that Pe, at p harmaceutically relevant concentrations and with apparent low cytotoxi city as determined by dye uptake, nonspecifically inhibits cytokine pr oduction by a toxic effect on transcriptional events.