2011 Annual Meeting

(306f) Comparative Analysis of Transcriptome and Lipidome of RAW 264.7 and Primary Macrophages

Authors

Eoin Fahy - Presenter, Department of Bioengineering, University of California San Diego
Ashok Reddy Dinasarapu - Presenter, Department of Bioengineering, University of California San Diego
Manish Sud - Presenter, Department of Bioengineering, University of California San Diego
Sean Li - Presenter, Department of Bioengineering, University of California San Diego
Shankar Subramaniam - Presenter, University of California, San Diego


Macrophages play essential roles in immunity and lipid homeostasis. Studies of macrophage biology have been significantly advanced by the availability of cell lines such as RAW264.7 cells.   However, it is unclear how these cell lines differ from primary macrophages, such as thioglycolate-elicited peritoneal macrophages (TGEM) and bone marrow-derived macrophages (BMDM).  We used the inflammatory stimulus Kdo2-Lipid A (KLA), a selective Toll-like receptor 4 agonist, to stimulate RAW264.7 and TGEM cells.  Temporal changes of lipid and gene expression levels were concomitantly measured.  We have performed a systems-level analysis of the lipidomic and transcriptomic data. In this work, we present a comprehensive comparison between the two cell types.

Upon KLA treatment, Both RAW264.7 and TGEM cells show strong inflammatory response on the gene expression level. However, relative to RAW264.7 cells, TGEM cells show more rapid and intense inflammatory response.  The increase in prostaglandin levels in both the primary cells is substantially less as compared to that in RAW264.7 cells. Sphingolipid-1-phosphate increases considerably in RAW264.7 cells.  Cholesterol de novo synthesis increases considerably in RAW264.7 cells, but 25-hyrdoxycholesterol, an endogenous agonist of liver X receptor, increases considerably in the TGEM cells. Specific commonalities and differences are also observed in energy metabolism related processes such as TCA cycle, beta oxidation and oxidative phosphorylation.

Our findings demonstrate that, although there are basic similarities in the responses of the three cell types, significant temporal and quantitative differences exist. Hence, caution is advised in using RAW264.7 cells as a model to study the kinetics of inflammatory response, lipid metabolism, and related disorders such as atherosclerosis.

Acknowledgement: The experimental data used in this work was provided by the Lipid Metabolite and Pathway Strategy (LIPID MAPS) Consortium experimental laboratories and is available on the LIPID MAPS web site (www.lipidmaps.org). LIPID MAPS is funded by the National Institute of General Medical Sciences.