Location: Arkansas Children's Nutrition CenterTitle: Isoflavone-free soy protein diet inhibits LPS-induced inflammatory responses Author
Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/11/2010
Publication Date: 4/25/2010
Citation: Goodwin, V.B., Greenway, A., Nagarajan, S. 2010. Isoflavone-free soy protein diet inhibits LPS-induced inflammatory responses. FASEB Journal. 24:326.3. Interpretive Summary: Asian populations have lower cardiovascular disease than the Western populations. Consumption of plant derived proteins have been implicated in the reduced incidence of cardiovascular disease in the Asian population. Earlier, we had reported that consumption of soy diet prevent the development of atherosclerosis. As chronic inflammation has been associated with the progression of atherosclerosis, in this study we tested the hypothesis that isoflavone-free soy diet may have anti-inflammatory properties. We found that dietary isoflavone free soy diet inhibits the inflammation-induced endothelial cell activation. Furthermore, this study demonstrated that the protective effects were due to the protein itself and not to the phytochemicals, like isoflavones, that are bound to the protein. Further research will determine the mechanisms.
Technical Abstract: Recently, we showed reduced atherosclerotic lesions in a hyperlipidemic mouse model fed isoflavone-free soy protein diet (SPI–) compared to casein (CAS)-fed mice, despite unchanged serum lipid levels. However, the molecular mechanisms contributing to the atheroprotective effect of soy-based diets is not clear. Atherosclerosis is a chronic inflammatory disease and interactions between endothelial cells and monocytes play a pivotal role in the initiation of atherosclerosis. We hypothesize that soy protein/peptides (SPI–) exert their protective effect by inhibiting inflammatory responses contributing to both acute and chronic inflammatory conditions. To address this hypothesis, a LPS-induced acute inflammation model in apoE–/– mouse was developed. Dose response studies showed LPS at 20 micro g/mouse is sufficient to induce CD54 and CD106, key endothelial cell adhesion molecules, expression in mouse aorta. Western blot analysis showed that aortas of SPI–-fed mice had reduced expression of CD106 compared to aortas of casein-fed mice. Further, quantitative RT-PCR analyses of proximal aorta also showed reduced CD106 mRNA expression in SPI–-fed compared to casein-fed mice. These findings suggest that the atheroprotective effect of isoflavone free soy diet is mediated, in part, by blocking inflammatory responses associated with atherosclerosis.