Stephanie Lehoux

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 Ikbkb gene in VSMCs significantly reduced the rate of aneurysm rupture in mice exposed to Ang II. In situ analysis further confirmed that the absence of IKKβ in VSMCs is associated with a reduced inflammatory response and the preservation of their contractile phenotypes. Our results reinforce the crucial role of VSMCs in rapid adaptation, leading to deleterious inflammation-dependent remodeling of the vascular wall, and define a previously unrecognized anabolic role of IKKβ in AAA pathogenesis.

Atherosclerosis is a chronic, systemic, inflammatory disease associated with the build‐up of fatty deposits (“plaques”) in the arteries. A major global health burden, severe atherosclerosis progresses to ischemic heart disease, an underlying condition which can exacerbate the occurrence of fatal events such as heart attack and stroke. Over the past two decades, the use of in vitro models to study atherosclerotic phenomena has increased, with the goal of complementing clinical research for drug and therapy development. In particular, 2D co‐culture models, and in the last decade, 3D spheroid models have been developed to improve our understanding of the atherosclerotic disease mechanism. However, the existing literature lacks information on the relevant parameters which should be considered prior and during the design of these models to promote model robustness and enhance their biomimetic capacities. This review provides an overview of such key parameters, as well as future perspectives on how existing limitations in the field of cell‐based in vitro model design can be improved. It is expected that by carefully considering these parameters, researchers will be better equipped with the required knowledge to develop biomedically and clinically relevant in vitro models.

[This corrects the article DOI: 10.3389/fcvm.2021.737934.].

The effects of low doses of ionizing radiation on atherosclerosis remain uncertain, particularly as regards the generation of pro- or anti-inflammatory responses, and the time scale at which such effects can occur following irradiation. To explore these phenomena, we exposed atheroprone ApoE^(−/−) mice to a single dose of 0, 0.05, 0.5 or 1 Gy of ¹³⁷Cs (γ) administered at a 10.35 mGy min⁻¹ dose rate and evaluated short-term (1–10 days) and long-term consequences (100 days). Bone marrow-derived macrophages were derived from mice 1 day after exposure. Irradiation was associated with a significant skewing of M0 and M2 polarized macrophages towards the M2 phenotype, as demonstrated by an increased mRNA expression of Retnla, Arg1, and Chil3 in cells from mice exposed to 0.5 or 1 Gy compared with non-irradiated animals. Minimal effects were noted in M1 cells or M1 marker mRNA. Concurrently, we observed a reduced secretion of IL-1β but enhanced IL-10 release from M0 and M2 macrophages. Effects of irradiation on circulating monocytes were most marked at day 10 post-exposure, when the 1 Gy dose was associated with enhanced numbers of both Ly6C^High and Ly6^Low cells. By day 100, levels of circulating monocytes in irradiated and non-irradiated mice were equivalent, but anti-inflammatory Ly6C^Low monocytes were significantly increased in the spleen of mice exposed to 0.05 or 1 Gy. Long term exposures did not affect atherosclerotic plaque size or lipid content, as determined by Oil red O staining, whatever the dose applied. Similarly, irradiation did not affect atherosclerotic plaque collagen or smooth muscle cell content. However, we found that lesion CD68+ cell content tended to decrease with rising doses of radioactivity exposure, culminating in a significant reduction of plaque macrophage content at 1 Gy. Taken together, our results show that short- and long-term exposures to low to moderate doses of ionizing radiation drive an anti-inflammatory response, skewing bone marrow-derived macrophages towards an IL-10-secreting M2 phenotype and decreasing plaque macrophage content. These results suggest a low-grade athero-protective effect of low and moderate doses of ionizing radiation.

Antigen-naive IgM-producing B cells are atheroprotective, whereas mature B cells producing class-switched antibodies promote atherosclerosis. Activation-induced cytidine deaminase (AID), which mediates class switch recombination (CSR), would thus be expected to foster atherosclerosis. Yet, AID also plays a major role in the establishment of B cell tolerance. We sought to define whether AID affects atherosclerotic plaque formation. We generated Ldlr^-/- chimeras transplanted with bone marrow from Aicda^-/- or wild-type (WT) mice, fed a HFD for 14 weeks. Decreased B cell maturation in Ldlr^-/-Aicda^-/- mice was demonstrated by 50% reduction in splenic and aortic BAFFR expression, a key signaling component of B2 cell maturation. This was associated with increased plasma IgM in Ldlr^–/-Aicda^-/- compared with Ldlr^-/-WT animals. Importantly, Ldlr^-/-Aicda^-/- mice had reduced atherosclerotic lesion area (0.20 ± 0.03mm²) compared with Ldlr^-/-WT (0.30 ± 0.04mm², P < 0.05), although no differences in plaque composition were noted between groups. In addition, immunofluorescence analysis revealed increased splenic B and T cell areas independent of cell number. AID depletion directly inhibits atherosclerotic plaque formation.

Atherosclerosis is the largest contributor toward life-threatening cardiovascular events. Cellular activity and cholesterol accumulation lead to vascular remodeling and the formation of fatty plaques. Complications arise from blood clots, forming at sites of plaque development, which may detach and result in thrombotic occlusions. Vascular smooth muscle cells and macrophages play dominant roles in atherosclerosis. A firm understanding of how these cells influence and modulate each other is pivotal for a better understanding of the disease and the development of novel therapeutics. Recent studies have investigated molecular interactions between both cell types and their impact on disease progression. Here we aim to review the current knowledge. Intercellular communications through soluble factors, physical contact, and extracellular vesicles are discussed. We also present relevant background on scientific methods used to study the disease, the general pathophysiology and intracellular factors involved in phenotypic modulation of vascular smooth muscle cells. We conclude this review with a discussion of the current state, shortcomings and potential future directions of the field.

The ability to target nanoparticles to the dysfunctional endothelium may present a new and innovative therapy for cardiovascular disease. In this work, an anti‐inflammatory gene therapy nanoparticle targeted to VCAM‐1, a protein overexpressed by inflamed endothelial cells located within atherosclerotic plaque, is developed. Targeting is accomplished via a peptide‐grafted coating for the nanoparticles. Nanoparticle binding to VCAM‐1 is probed via surface plasmon resonance with imaging to determine kinetics and binding dynamics. Targeted nanoparticles are internalized by transfected inflamed primary endothelial cells more than nontargeted controls (80% vs 30% positive cells) under both static and dynamic flow conditions. The nanoparticles also bind specifically to VCAM‐1+ endothelial cells within atherosclerotic plaque from mouse models in both the aortic sinus and whole aorta. Taken together, this nanoparticle formulation may be an effective and specific strategy for anti‐inflammatory therapy within the context of atherosclerosis.