Abdominal aortic aneurysm (AAA) is a serious disease with no effective pharmacological therapy. Although inflammation is recognized as a key regulator of AAA, targeting inflammatory pathways once the Show more
Abdominal aortic aneurysm (AAA) is a serious disease with no effective pharmacological therapy. Although inflammation is recognized as a key regulator of AAA, targeting inflammatory pathways once the disease is established does not improve outcomes. Understanding the earliest molecular indicators could clarify precise biological targets and prognostic markers for AAA. Using ApoE-deficient mice, we performed RNA-Seq on suprarenal abdominal aortas (SRAs) from Ang II- and saline-treated mice 24 h after infusion. We further developed a unique model of hyperlipidemic mice in which the expression of the inhibitor of nuclear factor kappa B kinase subunit beta (IKKβ) can be conditionally suppressed in vascular smooth muscle cells (VSMCs). RNA-Seq data revealed early IKKβ-dependent cellular anabolic processes in SRAs, including activation of the mammalian target of rapamycin complex 1 (mTORC1) pathway. Furthermore, deletion of the Show less
Arsenic exposure has been linked to an increased incidence of atherosclerosis. Previously, we have shown in vitro and in vivo that arsenic inhibits transcriptional activation of the liver X receptors Show more
Arsenic exposure has been linked to an increased incidence of atherosclerosis. Previously, we have shown in vitro and in vivo that arsenic inhibits transcriptional activation of the liver X receptors (LXRs), key regulators of lipid homeostasis. Therefore, we evaluated the role of LXRα in arsenic-induced atherosclerosis using the apoE(-/-) mouse model. Indeed, deletion of LXRα protected apoE(-/-) mice against the proatherogenic effects of arsenic. We have previously shown that arsenic changes the plaque composition in apoE(-/-) mice. Arsenic decreased collagen content in the apoE(-/-) model, and we have observed the same diminution in LXRα(-/-)apoE(-/-) mice. However, the collagen-producing smooth muscle cells (SMCs) were decreased in apoE(-/-), but increased in LXRα(-/-)apoE(-/-). Although transcriptional activation of collagen remained the same in SMC from both genotypes, arsenic-exposed LXRα(-/-)apoE(-/-) plaques had increased matrix metalloproteinase activity compared with both control LXRα(-/-)apoE(-/-) and apoE(-/-), which could be responsible for both the decrease in plaque collagen and the SMC invasion. In addition, arsenic increased plaque lipid accumulation in both genotypes. However, macrophages, the cells known to retain lipid within the plaque, were unchanged in arsenic-exposed apoE(-/-) mice, but decreased in LXRα(-/-)apoE(-/-). We confirmed in vitro that these cells retained more lipid following arsenic exposure and are more sensitive to apoptosis than apoE(-/-). Mice lacking LXRα are resistant to arsenic-enhanced atherosclerosis, but arsenic-exposed LXRα(-/-)apoE(-/-) mice still present a different plaque composition pattern than the arsenic-exposed apoE(-/-) mice. Show less