Infection with Trypanosoma cruzi, the protozoan parasite that causes Chagas disease, results in chronic infection that leads to cardiomyopathy with increased mortality and morbidity in endemic regions. In a companion study, our group found that a high fat diet protected mice from Trypanosoma cruzi-induced myocardial damage, and significantly reduced post-infection mortality. In the present study, the lethality of T. cruzi (Brazil strain) infection in CD-1 mice was reduced from 55% to 20% by an 8 week pre-feeding of a high fat diet (HFD) to induce obesity and the metabolic syndrome. The addition of metformin reduced mortality to 3%. It is an interesting observation as both the high fat diet and metformin, which are known to differentially attenuate host metabolism, effectively modified mortality in T. cruzi infected mice. In humans, the metabolic syndrome, as presently construed, produces immune activation and metabolic alterations that promote complications of obesity and diseases of later life, such as myocardial infarction, stroke, diabetes, Alzheimer's disease and cancer. Using an evolutionary approach, we hypothesized that for millions of years, the channeling of host resources into immune defenses starting early in life ameliorated the effects of infectious diseases, especially chronic infections, such as tuberculosis, and Chagas disease. In economically developed countries in recent times, with control of the common devastating infections, epidemic obesity, and lengthening of life span, the dwindling benefits of the immune activation in the first half of life have been overshadowed by the explosion of the syndrome's negative effects in later life.

AIF1 limits necrotic core expansion in atherosclerotic lesions.• AIF1 supports macrophage survival and efferocytotic activities.• AIF1 promotes NF-κB pathway activity in macrophages.• AIF1 induces NF-κB-dependent stress response, inflammatory, and anti-apoptotic gene expression in macrophages.• AIF1 promotes NF-κB pathway and limits apoptosis in atherosclerotic lesions in vivo.

Rationale: Remodeling of the vessel wall and the formation of vascular networks are dynamic processes that occur during mammalian embryonic development and in adulthood. Plaque development and excessive neointima formation are hallmarks of atherosclerosis and vascular injury. As our understanding of these complex processes evolves, there is a need to develop new imaging techniques to study underlying mechanisms. Objective: We used tissue clearing and light-sheet microscopy for 3-dimensional (3D) profiling of the vascular response to carotid artery ligation and induction of atherosclerosis in mouse models. Methods and Results: Adipo-Clear and immunolabeling in combination with light-sheet microscopy were applied to image carotid arteries and brachiocephalic arteries, allowing for 3D reconstruction of vessel architecture. Entire 3D neointima formations with different geometries were observed within the carotid artery and scored by volumetric analysis. Additionally, we identified a CD31-positive adventitial plexus after ligation of the carotid artery that evolved and matured over time. We also used this method to characterize plaque extent and composition in the brachiocephalic arteries of ApoE-deficient mice on high-fat diet. The plaques exhibited inter-animal differences in terms of plaque volume, geometry, and ratio of acellular core to plaque volume. A 3D reconstruction of the endothelium overlying the plaque was also generated. Conclusions: We present a novel approach to characterize vascular remodeling in adult mice using Adipo-Clear in combination with light-sheet microscopy. Our method reconstructs 3D neointima formation after arterial injury and allows for volumetric analysis of remodeling, in addition to revealing angiogenesis and maturation of a plexus surrounding the carotid artery. This method generates complete 3D reconstructions of atherosclerotic plaques and uncovers their volume, geometry, acellular component, surface, and spatial position within the brachiocephalic arteries. Our approach may be used in a number of mouse models of cardiovascular disease to assess vessel geometry and volume. Visual Overview: An online visual overview is available for this article.

Objective Smooth muscle cells (SMCs) contribute to neointima formation after vascular injury. Although β-catenin expression is induced after injury, whether its function is essential in SMCs for neointimal growth is unknown. Moreover, although inhibitors of β-catenin have been developed, their effects on SMC growth have not been tested. We assessed the requirement for SMC β-catenin in short-term vascular homeostasis and in response to arterial injury, and investigated the effects of β-catenin inhibitors on vascular SMC growth. Approach and Results We used an inducible, conditional genetic deletion of β-catenin in SMCs of adult mice. Uninjured arteries from adult mice lacking SMC β-catenin were indistinguishable from controls in terms of structure and SMC marker gene expression. After carotid artery ligation, however, vessels from mice lacking SMC β-catenin developed smaller neointimas, with lower neointimal cell proliferation and increased apoptosis. SMCs lacking β-catenin showed decreased mRNA expression of Mmp2, Mmp9, Sphk1 and S1pr1 (genes that promote neointima formation), higher levels of Jag1 and Gja1 (genes that inhibit neointima formation), decreased Mmp2 protein expression and secretion, and reduced cell invasion in vitro. Moreover, β-catenin inhibitors PKF118-310 and ICG-001 limited growth of mouse and human vascular SMCs in a dose-dependent manner. Conclusions SMC β-catenin is dispensable for maintenance of the structure and state of differentiation of uninjured adult arteries, but is required for neointima formation after vascular injury. Pharmacologic β-catenin inhibitors hinder growth of human vascular SMCs. Thus inhibiting β-catenin has potential as a therapy to limit SMC accumulation and vascular obstruction.