Maternal exposure to soy diet reduces atheroma in hyperlipidemic F1 offspring mice by promoting macrophage and T cell anti-inflammatory responses.

BACKGROUND AND AIMS: Maternal hypercholesterolemia has been implicated in earlier onset of atherosclerotic lesions in neonatal offspring. In this study, we investigated whether maternal exposure to soy protein isolate (SPI) diet attenuated the progression of atherosclerosis in F1 offspring. METHOD: Pregnant apolipoprotein E knockout (Apoe-/-) female mice were fed SPI diet until postnatal day 21 (PND21) of the offspring (SPI-offspring). SPI-offspring were switched at PND21 to casein (CAS) diet until PND140. Mice fed CAS throughout their lifetime (gestation to adulthood) were used as controls (CAS-offspring). RESULTS: Atherosclerotic lesions in the aortic sinuses were reduced in SPI-offspring compared with CAS-offspring. Total serum cholesterol levels in CAS-offspring or dams were comparable to levels in their SPI-counterparts, suggesting that alternative mechanisms contributed to the athero-protective effect of maternal SPI diet. Aortic VCAM-1, MCP-1, and TNF-α mRNA and protein expression, and expression of macrophage pro-inflammatory cytokines was reduced in SPI-offspring. Interestingly, CD4+ T cells from SPI-offspring showed reduced IFN-γ expression (Th1), while the expression of IL-10 (Th2/Treg), and IL-13 (Th2) was increased. DNA methylation analyses revealed that anti-inflammatory T cell-associated Gata3 and Il13 promoter regions were hypomethylated in SPI-offspring. These findings suggest that anti-inflammatory macrophage and T cell response may have contributed to the athero-protective effect in SPI-offspring. CONCLUSIONS: Our findings demonstrate that gestational and lactational soy diet exposure inhibits susceptibility to atherosclerotic lesion formation by promoting anti-inflammatory responses by macrophages and T cells.

Genital Chlamydia infection in hyperlipidemic mouse models exacerbates atherosclerosis.

BACKGROUND AND AIMS: Atherosclerosis is a chronic inflammatory disease, and recent studies have shown that infection at remote sites can contribute to the progression of atherosclerosis in hyperlipidemic mouse models. In this report, we tested the hypothesis that genital Chlamydia infection could accelerate the onset and progression of atherosclerosis. METHODS: Apolipoprotein E (Apoe-/-) and LDL receptor knockout (Ldlr-/-) mice on a high-fat diet were infected intra-vaginally with Chlamydia muridarum. Atherosclerotic lesions on the aortic sinuses and in the descending aorta were assessed at 8-weeks post-infection. Systemic, macrophage, and vascular site inflammatory responses were assessed and quantified. RESULTS: Compared to the uninfected groups, infected Apoe-/- and Ldlr-/- mice developed significantly more atherosclerotic lesions in the aortic sinus and in the descending aorta. Increased lesions were associated with higher circulating levels of serum amyloid A-1, IL-1ß, TNF-α, and increased VCAM-1 expression in the aortic sinus, suggesting an association with inflammatory responses observed during C. muridarum infection. Genital infection courses were similar in Apoe-/-, Ldlr-/-, and wild type mice. Further, Apoe-/- mice developed severe uterine pathology with increased dilatations. Apoe-deficiency also augmented cytokine/chemokine response in C. muridarum infected macrophages, suggesting that the difference in macrophage response could have contributed to the genital pathology in Apoe-/- mice. CONCLUSIONS: Overall, these studies demonstrate that genital Chlamydia infection exacerbates atherosclerotic lesions in hyperlipidemic mouse and suggest a novel role for Apoe in full recovery of uterine anatomy after chlamydial infection.

Soy protein inhibits inflammation-induced VCAM-1 and inflammatory cytokine induction by inhibiting the NF-κB and AKT signaling pathway in apolipoprotein E-deficient mice.

PURPOSE: Inflammation is a hallmark of many diseases, such as atherosclerosis, autoimmune diseases, obesity, and cancer. Isoflavone-free soy protein diet (SPI(-)) has been shown to reduce atherosclerotic lesions in a hyperlipidemic mouse model compared to casein (CAS)-fed mice, despite unchanged serum lipid levels. However, possible mechanisms contributing to the athero-protective effect of soy protein remain unknown. Therefore, we investigated whether and how SPI(-) diet inhibits inflammatory responses associated with atherosclerosis. METHODS: Apolipoprotein E knockout (apoE-/-) mice (5-week) were fed CAS or SPI(-) diet for 1 or 5 week to determine LPS- and hyperlipidemia-induced acute and chronic inflammatory responses, respectively. Expression of NF-κB-dependent inflammation mediators such as VCAM-1, TNF-α, and MCP-1 were determined in aorta and liver. NF-κB, MAP kinase, and AKT activation was determined to address mechanisms contributing to the anti-inflammatory properties of soy protein/peptides. RESULTS: Isoflavone-free soy protein diet significantly reduced LPS-induced VCAM-1 mRNA and protein expression in aorta compared to CAS-fed mice. Reduced VCAM-1 expression in SPI(-)-fed mice also paralleled attenuated monocyte adhesion to vascular endothelium, a critical and primary processes during inflammation. Notably, VCAM-1 mRNA and protein expression in lesion-prone aortic arch was significantly reduced in apoE-/- mice fed SPI(-) for 5 weeks compared with CAS-fed mice. Moreover, dietary SPI(-) potently inhibited LPS-induced NF-κB activation and the subsequent upregulation of pro-inflammatory cytokines, including TNF-α, IL-6, IL-1ß, and MCP-1. Interestingly, SPI(-) inhibited NF-κB-dependent inflammatory responses by targeting I-κB phosphorylation and AKT activation with no effect on MAP kinase pathway. Of the five putative soy peptides, four of the soy peptides inhibited LPS-induced VCAM-1, IL-6, IL-8, and MCP-1 protein expression in human vascular endothelial cells in vitro. CONCLUSIONS: Collectively, our findings suggest that anti-inflammatory properties of component(s) of soy protein/peptides may be a possible mechanism for the prevention of chronic inflammatory diseases such as atherosclerosis.

Attenuated atherosclerotic lesions in apoE-Fcγ-chain-deficient hyperlipidemic mouse model is associated with inhibition of Th17 cells and promotion of regulatory T cells.

Though the presence of antioxidized low-density lipoprotein IgG is well documented in clinical and animal studies, the role for FcγRs to the progression of atherosclerosis has not been studied in detail. In the current study, we investigated the role for activating FcγR in the progression of atherosclerosis using apolipoprotein E (apoE)-Fcγ-chain double-knockout (DKO) mice. Relative to apoE knockout (KO) mice, arterial lesion formation was significantly decreased in apoE-Fcγ-chain DKO mice. Bone marrow chimera studies showed reduced lesions in apoE KO mice receiving the bone marrow of apoE-Fcγ-chain DKO mice. Compared to apoE KO mice, antioxidized low-density lipoprotein IgG1 (Th2) and IgG2a (Th1), IL-10, and IFN-γ secretion by activated T cells was increased in apoE-Fcγ-chain DKO mice. These findings suggest that reduced atherosclerotic lesion in apoE-Fcγ-chain DKO mice is not due to a Th1/Th2 imbalance. Interestingly, the number of Th17 cells and the secretion of IL-17 by activated CD4(+) cells were decreased in apoE-Fcγ-chain DKO mice. Notably, the number of regulatory T cells, expression of mRNA, and secretion of TGF-ß and IL-10 were increased in apoE-Fcγ-chain DKO mice. Furthermore, secretions of IL-6 and STAT-3 phosphorylation essential for Th17 cell genesis were reduced in apoE-Fcγ-chain DKO mice. Importantly, decrease in Th17 cells in apoE-Fcγ-chain DKO mice was due to reduced IL-6 release by APC of apoE-Fcγ-chain DKO mice. Collectively, our data suggest that activating FcγR promotes atherosclerosis by inducing a Th17 response in the hyperlipidemic apoE KO mouse model.

Dietary rice protein isolate attenuates atherosclerosis in apoE-deficient mice by upregulating antioxidant enzymes.

Rice-based diets may have been reported to protect against the development of atherosclerosis; however, the underlying mechanism(s) for this protection remains unknown. In this report, the mechanism(s) contributing to the atheroprotective effects of rice-based diet was addressed using the apolipoprotein E knockout (apoE-/-) mice fed rice protein isolate (RPI) or casein (CAS). Reduced atherosclerotic lesions were observed in aortic sinus and enface analyses of the descending aorta in RPI-fed apoE-/- mice compared with CAS-fed mice. Plasma total- and HDL-cholesterol levels were not different amongst the two groups, suggesting alternative mechanism(s) could have contributed to the atheroprotective effect of rice-based diets. Plasma oxLDL and anti-oxLDL IgG levels were significantly decreased in RPI-fed compared to CAS-fed animals. Plasma and aortic tissue GSH levels and GSH:GSSG ratio were higher in RPI-fed mice compared to CAS-fed group. Interestingly, RPI feeding increased mRNA and protein expression of superoxide dismutase, and mRNA expression of catalase, glutathione peroxidase and glutathione reductase, key antioxidant enzymes implicated inhibiting oxidative stress leading to atherosclerosis. In conclusion, these findings suggest that the reduction in atherosclerotic lesions observed in mice fed the rice-based diet is mediated in part by inhibiting oxidative stress and subsequent oxLDL generation that could result in reduced foam cell formation, an early event during atherogenesis.

Dietary soy protein isolate ameliorates atherosclerotic lesions in apolipoprotein E-deficient mice potentially by inhibiting monocyte chemoattractant protein-1 expression.

Soy-based diets reportedly protect against the development of atherosclerosis; however, the underlying mechanism(s) for this protection remains unknown. In this report, the mechanism(s) contributing to the atheroprotective effects of a soy-based diet was addressed using the apolipoprotein E knockout (apoE-/-) mice fed soy protein isolate (SPI) associated with or without phytochemicals (SPI+ and SPI-, respectively) or casein (CAS). Reduced atherosclerotic lesions were observed in aortic sinus and enface analyses of the descending aorta in SPI+- or SPI(-)-fed apoE-/- mice compared with CAS-fed mice. SPI+-fed mice showed 20% fewer lesions compared with SPI(-)-fed mice. Plasma lipid profiles did not differ among the 3 groups, suggesting alternative mechanism(s) could have contributed to the atheroprotective effect of soy-based diets. Real-time quantitative PCR analyses of proximal aorta showed reduced expression of monocyte chemoattractant protein-1 (MCP-1), a monocyte chemokine, in mice fed both soy-based diets compared with the CAS-fed mice. These findings paralleled the reduced number of macrophages observed in the lesion site in the aorta of SPI+- or SPI(-)-fed mice compared with CAS-fed mice. In an in vitro LPS-induced inflammation model, soy isoflavones (genistein, daidzein, and equol alone or in combination) dose dependently inhibited LPS-induced MCP-1 secretion by macrophages, suggesting a role for soy isoflavones for the protective in vivo effects. Collectively, these findings suggest that the reduction in atherosclerotic lesions observed in mice fed the soy-based diet is mediated in part by inhibition of MCP-1 that could result in reduced monocyte migration, an early event during atherogenesis.