Gut Microbiota-Derived Trimethylamine N-Oxide Contributes to Abdominal Aortic Aneurysm Through Inflammatory and Apoptotic Mechanisms.

BACKGROUND: Large-scale human and mechanistic mouse studies indicate a strong relationship between the microbiome-dependent metabolite trimethylamine N-oxide (TMAO) and several cardiometabolic diseases. This study aims to investigate the role of TMAO in the pathogenesis of abdominal aortic aneurysm (AAA) and target its parent microbes as a potential pharmacological intervention. METHODS: TMAO and choline metabolites were examined in plasma samples, with associated clinical data, from 2 independent patient cohorts (N=2129 total). Mice were fed a high-choline diet and underwent 2 murine AAA models, angiotensin II infusion in low-density lipoprotein receptor-deficient (Ldlr-/-) mice or topical porcine pancreatic elastase in C57BL/6J mice. Gut microbial production of TMAO was inhibited through broad-spectrum antibiotics, targeted inhibition of the gut microbial choline TMA lyase (CutC/D) with fluoromethylcholine, or the use of mice genetically deficient in flavin monooxygenase 3 (Fmo3-/-). Finally, RNA sequencing of in vitro human vascular smooth muscle cells and in vivo mouse aortas was used to investigate how TMAO affects AAA. RESULTS: Elevated TMAO was associated with increased AAA incidence and growth in both patient cohorts studied. Dietary choline supplementation augmented plasma TMAO and aortic diameter in both mouse models of AAA, which was suppressed with poorly absorbed oral broad-spectrum antibiotics. Treatment with fluoromethylcholine ablated TMAO production, attenuated choline-augmented aneurysm initiation, and halted progression of an established aneurysm model. In addition, Fmo3-/- mice had reduced plasma TMAO and aortic diameters and were protected from AAA rupture compared with wild-type mice. RNA sequencing and functional analyses revealed choline supplementation in mice or TMAO treatment of human vascular smooth muscle cells-augmented gene pathways associated with the endoplasmic reticulum stress response, specifically the endoplasmic reticulum stress kinase PERK. CONCLUSIONS: These results define a role for gut microbiota-generated TMAO in AAA formation through upregulation of endoplasmic reticulum stress-related pathways in the aortic wall. In addition, inhibition of microbiome-derived TMAO may serve as a novel therapeutic approach for AAA treatment where none currently exist.

Effect of combining aspirin and rivaroxaban on atherosclerosis in mice.

BACKGROUND AND AIMS: The platelet inhibitor aspirin reduces inflammation and atherosclerosis in both apolipoprotein E deficient (apoE-/-) mice and low-density lipoprotein receptor deficient (Ldlr-/-) mice. Similarly, the factor Xa inhibitor rivaroxaban reduces atherosclerosis in both apoE-/- and Ldlr-/- mice. We tested the hypothesis that the combination of aspirin and rivaroxaban reduces atherosclerosis in mice to a greater extent than either agent alone. METHODS: Male Ldlr-/- mice were fed a western-type diet for 12 weeks to induce atherosclerosis. Cohorts of mice received aspirin in the water and/or rivaroxaban in the diet. Atherosclerosis and lesion composition were measured in the aortic sinus and the aorta. Expression of 55 proteins in the aorta and plasma was determined using multiplex ELISA assays. RESULTS: Aspirin alone, rivaroxaban alone, and the combination of both agents significantly reduced atherosclerosis in the Ldlr-/- mice compared with control Ldlr-/- mice fed a western-type diet. However, there were no significant differences in atherosclerosis in the group receiving aspirin and rivaroxaban compared with the groups that received aspirin or rivaroxaban alone. Aspirin, rivaroxaban and the combination reduced macrophage content and apoptosis in the lesions compared with controls but there was no difference between the three treatment groups. We observed statistically significant changes in the expression of a small number of proteins in the aorta and plasma in mice treated with aspirin and/or rivaroxaban. CONCLUSIONS: Contrary to our expectation, the combination of aspirin and rivaroxaban did not further reduce atherosclerosis in Ldlr-/- mice beyond the level observed with each agent alone.

Adipocyte-specific deletion of HuR induces spontaneous cardiac hypertrophy and fibrosis.

Adipose tissue homeostasis plays a central role in cardiovascular physiology, and the presence of thermogenically active brown adipose tissue (BAT) has recently been associated with cardiometabolic health. We have previously shown that adipose tissue-specific deletion of HuR (Adipo-HuR-/-) reduces BAT-mediated adaptive thermogenesis, and the goal of this work was to identify the cardiovascular impacts of Adipo-HuR-/-. We found that Adipo-HuR-/- mice exhibit a hypercontractile phenotype that is accompanied by increased left ventricle wall thickness and hypertrophic gene expression. Furthermore, hearts from Adipo-HuR-/- mice display increased fibrosis via picrosirius red staining and periostin expression. To identify underlying mechanisms, we applied both RNA-seq and weighted gene coexpression network analysis (WGCNA) across both cardiac and adipose tissue to define HuR-dependent changes in gene expression as well as significant relationships between adipose tissue gene expression and cardiac fibrosis. RNA-seq results demonstrated a significant increase in proinflammatory gene expression in both cardiac and subcutaneous white adipose tissue (scWAT) from Adipo-HuR-/- mice that is accompanied by an increase in serum levels of both TNF-α and IL-6. In addition to inflammation-related genes, WGCNA identified a significant enrichment in extracellular vesicle-mediated transport and exosome-associated genes in scWAT, whose expression most significantly associated with the degree of cardiac fibrosis observed in Adipo-HuR-/- mice, implicating these processes as a likely adipose-to-cardiac paracrine mechanism. These results are significant in that they demonstrate the spontaneous onset of cardiovascular pathology in an adipose tissue-specific gene deletion model and contribute to our understanding of how disruptions in adipose tissue homeostasis may mediate cardiovascular disease.NEW & NOTEWORTHY The presence of functional brown adipose tissue in humans is known to be associated with cardiovascular health. Here, we show that adipocyte-specific deletion of the RNA binding protein HuR, which we have previously shown to reduce BAT-mediated thermogenesis, is sufficient to mediate a spontaneous development of cardiac hypertrophy and fibrosis. These results may have implications on the mechanisms by which BAT function and adipose tissue homeostasis directly mediate cardiovascular disease.

Percutaneous cannulated screw fixation in the treatment for diabetic ankle fractures.

BACKGROUND: Diabetic ankle fractures were usually treated by open reduction and internal fixation (ORIF) which may lead to Charcot joint, or conservative which may lead to pressure sores. For better results, minimally invasive procedures have been developed, which decrease complications and enable early mobilization and rapid rehabilitation. MATERIALS AND METHODS: This is a retrospective study of a total of 26 uncontrolled diabetic patients: 8 males [30.8%] and 18 females [69.2%]. The mean age of the patients was 67.4 (range 60 to 75) years. We include only Weber A and B where 10 patients suffered from lateral malleolus only (38.5%), 11 patients with bi-malleolar ankle fracture (42.3%) and 5 patients with tri-malleolar fracture (19.2%). RESULTS: The mean time to union was 6.92 weeks (range of 6 to 12 weeks). Weight-bearing has begun from the first day in 19 patients (73.1%), while 7 patients began weight-bearing 4 weeks after the operation (26.9%). Mean follow-up ranged from 2 to 5 years. Mean AOFAS was 96.12 (range of 60 to 99). Only 3 patients suffered from complication: One patient suffered from Charcot joint, one suffered from fracture displacement and needed revision, and one suffered from mal-reduction. Thus, the complication rate was 11.5%. CONCLUSION: We believe that percutaneous cannulated screws technique is a simple and effective method that can be applied safely in uncontrolled DM patients with ankle fractures.