Location: Arkansas Children's Nutrition CenterTitle: Over-expression of 12/15-lipoxygenase increases oxldl-induced pro-inflammatory mediator expression and foam cell formation in rodent macrophages Author
Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 12/15/2011
Publication Date: 4/1/2012
Citation: Thakali, K.M., Kang, J., Wu, X. 2012. Over-expression of 12/15-lipoxygenase increases oxldl-induced pro-inflammatory mediator expression and foam cell formation in rodent macrophages. The Federation of American Societies for Experimental Biology Journal. 26 (Meeting Abstracts):644.17. Interpretive Summary: We previously reported that consumption of blueberries can prevent the development of atherosclerosis in mice prone to rapidly developing this disease. Also, consumption of blueberries was associated with decreased expression of 12/15-lipoxygenase, an enzyme important in the development of atherosclerosis. The purpose of this study was to further understand the link between blueberries and 12/15-lipoxygenase. To answer this question, we inserted the 12/15-lipoxygenase gene into a macrophage cell that normally lacks this protein. Insertion of 12/15-lipoxygenase into the macrophages increased expression of inflammatory markers and proteins involved in cholesterol uptake, while decreasing expression of proteins involved in cholesterol efflux. The next step of this study is to see if blueberries can prevent the effects of 12/15-lipoxygenase over-expression in macrophages so we can further understand how blueberries prevent the development of atherosclerosis.
Technical Abstract: Blueberries (BB) prevent the development of atherosclerosis in apoE deficient mice, partly through suppressing 12/15-lipoxygenase (12/15-LOX) expression and reducing the production of oxidized lipid products. To further study the role of 12/15-LOX in atherosclerosis and investigate the inhibitory effects of BB, a rodent macrophage cell line RAW264.7 was transfected with the 12/15-LOX gene to investigate over-expression of this enzyme on oxLDL-induced inflammatory mediator production and foam cell formation. Over-expression of 12/15-LOX increased gene expression of the pro-inflammatory mediators TNF-a, RANTES and MIP in macrophage stimulated with oxLDL, which was accompanied by increased NF-'B activity as measured by a SEAP reporter assay. When induced by oxLDL, over-expression of 12/15-LOX showed increased gene expression of two scavenger receptors (CD36 and SR-A) and the reduction of two ATP-binding cassette transporters (ABCA1 and ABCG1) expression. When assessed with Oil Red O staining, foam cell formation was increased in macrophages that over-expressed 12/15-LOX. Our data suggest that over-expression of 12/15-LOX contributes to a pro-atherogenic phenotype. Further investigations of mechanisms underlying suppression of 12/15-LOX by BB feeding are in progress.