Inhibitory effects of novel hydrophilic cyclodextrin derivatives on nitricoxide production in macrophages stimulated with lipopolysaccharide

Purpose. The objective of this study is to examine the effects of cyclodext rins (CyDs) on nitric oxide (NO) production in macrophages stimulated with lipopolysaccharide (LPS), Methods. RAW264.7 cells, a mouse macrophage-like cell, were used. Cytotoxic ity of CyDs was evaluated by WST-1 method. Nitrite, iNOS, and iNOS mRNA wer e determined by Griess method, Western blotting, and reverse transcription- polymerase chain reaction (RT-PCR) analysis, respectively. The interaction of LPS with CyDs was evaluated by utilizing a competitive inclusion phenome non. The binding of FITC-labeled LPS to the surface of RAW264.7 cells was m easured by a flow cytometry, Results. Of 15 CyDs, 2,6-di-O-methyl-alpha -CyD (DM-alpha -CyD), and 2,6-di -O-methyl-3-O- acetyl-beta -cyclodextrin (DMA-beta -CyD) had greater inhibi tory activity than did the other CyDs against NO production in RAW264.7 cel ls stimulated with LPS, without showing any cytotoxicity. DM-alpha -CyD and DMA-beta -CyD specifically inhibited the increase in iNOS and iNOS mRNA le vels elicited by stimulation with LPS in RAW264.7 cells, DM-alpha -CyD and DMA-beta -CyD suppressed the binding of FITC-labeled LPS to the surface of cells, probably resulting in inhibitory effects on iNOS expression and NO p roduction. DM-alpha -CyD had a greater interaction with RAW264.7 cells than did DMA-beta -CyD. The pretreatment of RAW264.7 cells with DM-alpha -CyD, not DMA-beta -CyD, decreased the LPS binding to the cell surface. The resul ts suggested that the inhibitory mechanism of the LPS binding to the cell s urface is different between DM-alpha -CyD and DMA-beta -CyD. Conclusions. The present results suggest that DM-alpha -CyD and DMA-beta -C yD attenuates NO production by inhibiting iNOS gene expression in RAW264.7 cells stimulated with LPS, probably due to the suppression of LPS binding t o LPS receptors on the cells in the different way.