Activation of inducible nitric oxide synthase by Kagamjuaguiem in peritoneal macrophages in mice.

BACKGROUND & OBJECTIVE: A Korean herbal formula Kagamjuaguiem (KJE) has been used for the purpose of the tumour therapy. However, its mechanism of action is not clear. Nitric oxide (NO) as a potent macrophage-derived effector molecule against a variety of tumours has received increasing attention. In this study, using mouse peritoneal macrophages, we have examined the mechanism by which KJE regulates NO production.

METHODS

Peritoneal macrophages were cultured with recombinant interferon-gamma (gammaIFN-gamma) for 6 h. The cells were then stimulated with various concentrations of KJE. NO synthesis in cell cultures was measured by Griess method, and inducible NOS expression was measured by western blotting. The amount of tumour necrosis factor-alpha (TNF-alpha) secreted by the cell was measured by a modified enzymelinked immunosorbent assay.

RESULTS

When KJE was used in combination with gammaIFN-gamma there was a marked co-operative induction of NO production. However, KJE had no effect on NO production by itself. The increased production of NO from rIFN-gamma plus KJE-stimulated cells was almost completely inhibited by pre-treatment with pyrrolidine dithiocarbamate, an inhibitor of nuclear factor kappa B (NF-kappaB). Further, treatment of peritoneal macrophages with rIFN-gamma plus KJE caused a significant increase in TNF-alpha production.

INTERPRETATION & CONCLUSION: Our findings demonstrate that KJE increases the production of NO and TNF-alpha by rIFN-gamma-primed macrophages and suggest that NF-kappaB plays a critical role in mediating these effects of KJE.