Disruption of tumor necrosis factor-alpha gene diminishes the development of atherosclerosis in ApoE-deficient mice.

Inflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha) have been implicated in atherogenesis. However, the precise role of TNF-alpha in atherogenesis is still unclear. To examine the effect of TNF-alpha on atherogenesis, we generated compound-deficient mice in apolipoprotein E (apoE) and TNF-alpha (apoE-/-/TNF-alpha-/-) and compared them with apoE-/- mice. Although serum total cholesterol levels were markedly elevated in both apoE-/-/TNF-alpha-/- and apoE-/- mice compared to wild-type mice, no differences were observed between apoE-/-/TNF-alpha-/- and apoE-/- mice. The atherosclerotic plaque area in the aortic luminal surface of apoE-/-/TNF-alpha-/- mice (n=8, 3.1+/-0.4%) was significantly smaller than that of apoE-/- mice (n=7, 4.7+/-0.4%, p<0.001) despite the lack of difference in serum cholesterol levels. The atherosclerotic lesion size in the aortic sinus of apoE-/-/TNF-alpha-/- mice (n=10, 5.1+/-0.3 x 10(5)microm(2)) was also significantly smaller than that of apoE-/- mice (n=11, 7.0+/-0.3 x 10(5)microm(2), p<0.0001). RT-PCR analysis indicated that the expression levels of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1) were significantly higher in apoE-/- than apoE-/-/TNF-alpha-/- mice. Macrophages from apoE(-/-) mice showed higher uptake level of oxidized LDL and increased expression level of scavenger receptor class A (SRA) compared to those from apoE-/-/TNF-alpha-/- mice. These results indicate that TNF-alpha plays an atherogenic role by upregulating the expressions of ICAM-1, VCAM-1 and MCP-1 in the vascular wall, and by inducing SRA expression and oxidized LDL uptake in macrophages.

Interferon-gamma produced by bone marrow-derived cells attenuates atherosclerotic lesion formation in LDLR-deficient mice.

BACKGROUND: We evaluated the role of IFN-gamma produced by bone marrow-derived cells in atherogenesis in LDLR(-/-) mice using bone marrow transplantation (BMT). METHODS AND RESULTS: We generated IFN-gamma-deficient bone marrow transplanted LDLR(-/- )mice (IFN-gamma(-/-) BMT mice), and compared them with controls (IFN-gamma(+/+) BMT mice). These mice were fed a high-fat diet (HFD). Plasma total cholesterol and triglyceride levels did not differ between these two groups. After 6 weeks of HFD feeding, the atherosclerotic lesions of IFN-gamma(-/-) BMT mice were larger than those of IFN-gamma(+/+) BMT mice at the aortic sinus, aortic arch and abdominal aorta. After 12 weeks of HFD feeding, the significant differences between the two groups disappeared except for the atherosclerotic lesion in the aortic sinus. MOMA2, CD4, CD8 or alpha-smooth muscle actin-positive cells were detected in the atherosclerotic lesions. The cellular composition of the lesions was identical between the two groups, but the cellular density showed decreased concomitant with the increased extracellular matrix deposition in IFN-gamma(-/- )BMT mice. CONCLUSIONS: These findings demonstrate that IFN-gamma produced by bone marrow-derived cells delays the progression of atherosclerosis without any effect on plasma lipids, and this suppression may be due to decreased extracellular matrix deposition.

Lack of interleukin-1beta decreases the severity of atherosclerosis in ApoE-deficient mice.

OBJECTIVE: Atherosclerosis is considered to be a chronic inflammatory disease and many cytokines participate in the development of atherosclerosis. We focused on the role of interleukin-1beta (IL-1beta), one of the proinflammatory cytokines secreted by monocytes/macrophages, in the progression of atherosclerosis. METHODS AND RESULTS: We generated mice lacking both apoE and IL-1beta. The sizes of atherosclerotic lesions at the aortic sinus in apoE-/-/IL-1beta-/-mice at 12 and 24 weeks of age showed a significant decrease of approximately 30% compared with apoE-/-/IL-1beta+/+ mice, and the percentage of the atherosclerotic area to total area of apoE-/-/IL-1beta-/- at 24 weeks of age also showed a significant decrease of about 30% compared with apoE-/-/IL-1beta+/+. The mRNA levels of vascular cell adhesion molecule (VCAM)-1 and monocyte chemotactic protein-1 in the apoE-/-/IL-1beta-/- aorta were significantly reduced compared with the apoE-/-/IL-1beta+/+. Furthermore, VCAM-1 was also reduced at the protein level in apoE-/-/IL-1beta-/- aorta compared with apoE-/-/IL-1beta+/+. CONCLUSIONS: The lack of IL-1beta decreases the severity of atherosclerosis in apoE deficient mice, possibly through increased expressions of VCAM-1 and monocyte chemotactic protein-1 in the aorta.