No abstract

The antiatherogenic effects of soy isoflavone consumption have been demonstrated in a variety of studies. However, the mechanisms involved remain poorly defined. Adhesion of monocytes to vascular endothelial cells is a key step within the inflammatory cascade that leads to atherogenesis. Many factors, including the physical forces associated with blood flow, regulate this process. Using an in vitro flow assay, we report that genistein, a principal component of most isoflavone preparations, inhibits monocyte adhesion to cytokine (TNF-alpha)-stimulated human vascular endothelial cells at physiologically relevant concentrations (0-1 microM). This effect is absolutely dependent on flow and is not observed under static conditions. Furthermore, this inhibition was dependent on activation of endothelial peroxisomal proliferator-activated receptor-gamma. No significant role for other reported properties of genistein, including antioxidant effects, inhibition of tyrosine kinases, or activation of estrogen receptors, was observed. Furthermore, the antiadhesive effects of genistein did not occur via modulation of the adhesion molecules E-selectin, ICAM-1, VCAM-1, or platelet-endothelial cell adhesion molecule-1. These data reveal a novel anti-inflammatory mechanism for isoflavones and identify the physical forces associated with blood flow and a critical mediator of this function.

The mechanisms by which isoflavones protect against inflammatory vascular disease remain unclear. Our previous observations suggest that one mechanism involves inhibition of monocyte-endothelial cell interactions in a process that is absolutely dependent on flow. The molecular mechanisms involved and the effects of structurally distinct isoflavones on this process are not known and are investigated herein. Using static and flow-dependent monocyte adhesion assays, our data show that exposure of endothelial cells to biologically relevant concentrations of isoflavones inhibits subsequent TNF-alpha induced monocyte adhesion only during flow. This inhibition involved activating endothelial PPARgamma by stimulating promoter sequences containing the PPARgamma response element by isoflavones and attenuating antiadhesive effects by siRNA targeting of PPARgamma. A comparison of structurally distinct isoflavones suggested a critical role for the A-ring. Using chlorinated derivatives of daidzein, a key structural requirement for PPARgamma agonist activity appears to be the presence of the 7-OH group and the lack of chlorine at the 6- or 8-positions in the A-ring. Collectively, these data support 1) a novel flow-dependent anti-inflammatory mechanism for PPARgamma ligands in vascular endothelial cells and 2) exemplify the current concepts of nutrients modulating disease via regulating specific cell signaling pathways.

No abstract

The distribution of two monoclonal antibodies with reactivity against human leukemia/lymphoma associated antigens (BA-1 antibody) and carcinoembryonic antigen (202 antibody) when labeled with 131I or 111In was studied in normal Balb/c mice. The BA-1 antibody of the IgM subclass was labeled with 131I by the micro iodine monochloride method at a 12:1 molar ratio and with 111In by the cyclic DTPA anhydride method at a 10:1 molar ratio. In vitro, the 131I-labeled BA-1 antibody bound 35.5% to 10(7) KM-3 leukemic cells while the 111In-labeled BA-1 antibody bound 29.9% to the same number of KM-3 cells. In vivo, the 111In-labeled BA-1 antibody showed a higher accumulation in liver, spleen, and kidney than the 131I-labeled BA-1 antibody. The 202 antibody of the IgG1 subclass was labeled with 131I at a 5:1 molar ratio and with 111In at a 7:1 molar ratio. In vitro, the 131I-labeled 202 antibody bound 30.9%, 27.4%, and 30.0% to 10(7) CO-112, WIDR, and LS-174T colon cancer cells, respectively. The 111In-labeled 202 antibody bound 20.5%, 30.2%, and 33.6%, respectively to the same number of colon cancer cells. In vivo, the 131I-labeled 202 antibody showed a higher tissue to blood ratio in liver, spleen, and kidney than the 111In-labeled 202 antibody. The data indicate that the relative distribution of 131I-labeled versus 111In-labeled monoclonal antibody may depend on the immunoglobulin subclass of the antibody and the molar ratio used in labeling.