Repression of Proinflammatory Gene Expression by Lipid Extract of Nostoc commune var sphaeroides Kützing, a Blue-green Alga, via Inhibition of Nuclear Factor-κB in RAW 264.7 Macrophages

Authors

Young-Ki Park, University of Nebraska-Lincoln
Heather E. Rasmussen, University of Nebraska-LincolnFollow
Sarah J. Ehlers, University of Nebraska-Lincoln
Kara R. Blobaum, University of Nebraska-Lincoln
Fan Lu, Algaen Corporation
Vicki L. Schlegel, University of Nebraska-LincolnFollow
Timothy P. Carr, University of Nebraska-LincolnFollow
Ji-Young Lee, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2-2008

Citation

Nutrition Research 28:2 (February 2008), pp. 83–91.

doi: 10.1016/j.nutres.2007.11.008

Comments

Copyright © 2008 Elsevier, Inc. Used by permission.

Abstract

We investigated whether lipid extract from a blue-green alga, N. commune, modulates proinflammatory gene expression in RAW 264.7 macrophages. The cells were incubated with N. commune lipid extract (0–100 μg/mL) and subsequently activated by LPS (100 ng/mL). Quantitative real-time PCR analysis showed that mRNA abundance of proinflammatory mediators, including TNF-α, COX-2, IL-1β, IL-6, and iNOS, was significantly reduced by N. commune lipid extract in a dose-dependent manner. Secretion of TNF-α and IL-1β into cell culture medium was also significantly decreased by N. commune lipid extract. Thin-layer chromatography-densitometry analysis showed that N. commune lipid extract contained approximately 15% of fatty acids. To determine whether the inhibition of proinflammatory mediator production by N. commune lipid extract is primarily conferred by fatty acids in the lipid extract, macrophages were incubated with 100 μg/mL of N. commune lipid extract or 15 μg/mL of a fatty acid mixture, which was formulated to reflect the fatty acid composition of N. commune lipid extract. The fatty acid mixture significantly reduced RNA abundance of TNF-α and COX-2, but to a lesser extent than did the N. commune lipid extract, suggesting the presence of additional bioactive compounds with an anti-inflammatory property in the lipid extract. As NF-κB is a major regulator for the proinflammatory gene expression, we measured its DNA-binding activity. DNA-binding activity of NF-κB was significantly reduced by N. commune lipid extract. In conclusion, our study suggests that N. commune lipid extract represses the expression of proinflammatory genes in RAW 264.7 macrophages, at least in part, by inhibiting the activation of NF-κB pathway.