Mizoribine Inhibits Production of Pro-inflammatory Cytokines and PGE2 in Macrophages

BACKGROUND: Mizoribine (MZR) is an imidazole nucleoside isolated from Eupenicillium brefeldianum. MZR is currently in clinical use for patients who have undergone renal transplantation. Therapeutic efficacy of MZR has also been demonstrated in rheumatoid arthritis and lupus nephritis. MZR has been shown to inhibit the proliferation of lymphocytes by interfering with inosine monophosphate dehydrogenase. Since the exact mechanism by which MZR benefits rheumatoid arthritis (RA) is not clear, we investigated the ability of MZR to direct its immunosuppressive influences on other antigen presenting cells, such as macrophages. METHODS: Mouse macrophage RAW264.7 cells were stimulated with lipopolysaccharide in the presence of MZR. To elucidate the mechanism of the therapeutic efficacy in chronic inflammatory diseases, we examined the effects of MZR on the production of pro-inflammatory cytokines, nitric oxide (NO) and prostaglandin E2 (PGE2) in macrophages. RESULTS: MZR dose-dependently decreased the production of nitric oxide and pro- inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukins 1beta (IL-beta) and IL-6 PGE2. Examination of gene expression levels showed that the anti-inflammatory effect correlated with the down-regulation of inducible nitiric oxide synthase expression, cycloxygenase-2 expression and TNF-alpha gene expression. CONCLUSION: In this work, we resulted whether MZR (1.25~10 microgram/ml) inhibited macrophage activation by inhibiting secretion of pro-inflammatory cytokines, NO and PGE2. These findings provide an explanation for the therapeutic efficacy of MZR in chronic inflammation- associated diseases.

Activation of Macrophages by the Components Produced from Cordyceps militaris

BACKGROUND: Cordyceps militaris have been reported to modify the immune and inflammatory responses both in vivo and in vitro. Macrophages play important roles in the innate immunity through the phagocytosis of antigens. This study examined the effects of Cordyceps militaris on the activation of murine macrophage RAW 264.7 cells and primary macrophages. METHODS: The components contained in culture broth of Cordyceps militaris were purified by propyl alcohol extraction and HP 20 column chromatography to CMDB, CMDBW, CMDB5P, and CMDB25P. The amounts of nitric oxide (NO) were determined by using ELISA, Griess reagent respectively. The amounts of some cytokines were determined by using ELISA, western blot, and RT-PCR. The expression levels of cell surface molecules (ICAM-1, B7-1 and B7-2) were measured by flow cytometric analysis. RESULTS: All the components of Cordyceps militaris produced significant amounts of NO. In particular, CMDB produced much more NO in RAW 264.7 cells and primary macrophages than other fractions of Cordyceps militaris. CMDB increased significantly the production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 dose-dependently in RAW 264.7 cells. Examination of the gene expression level also showed that the enhanced production of cytokines was correlated with the up-regulation of i-NOS expression, cycloxygenase (COX)-2 expression, IL-1beta and IL-6 expression, and TNF-alpha expression on the expression of mRNAs by semi-quantitative RT-PCR. Western blot analysis also confirmed that CMDB enhances the expression level of these cytokines. CONCLUSION: These results show that CMDB stimulates the production of NO and pro-inflammatory cytokines and can also up-regulate the gene expression levels in macrophages.