Background Perivascular adipose tissue (PVAT) surrounds most vessels and shares common features with brown adipose tissue (BAT). Whereas adaptive thermogenesis in BAT increases energy expenditure and is beneficial for metabolic diseases, little is known on the role of PVAT in vascular diseases such as atherosclerosis. We hypothesize that the thermogenic function of PVAT regulates intravascular temperature and reduces atherosclerosis. Methods and Results PVAT shares similar structural and proteomics with BAT. We demonstrate that PVAT has thermogenic properties similar to BAT in response to cold stimuli in vivo. Proteomics analysis of the PVAT from mice housed in a cold environment identified differential expression in proteins highly related with cellular metabolic processes. In a mouse model deficient in PPARγ in smooth muscle cells (SMPG KO mice), we uncovered a complete absence of PVAT surrounding the vasculature likely due to PPARγ deletion also in the perivascular adipocyte precursor cells. Lack of PVAT, resulting in loss of its thermogenic activity, impairs vascular homeostasis causing temperature loss and endothelial dysfunction. We further show that cold exposure inhibits atherosclerosis and improves endothelial function in mice with intact PVAT, but not in SMPG KO mice, as a result of impaired lipid clearance. Pro-inflammatory cytokine expression in PVAT is not altered upon cold exposure. Finally, prostacyclin released from PVAT contributes to the vascular protection against endothelial dysfunction. Conclusions PVAT is a vasoactive organ with functional characteristics similar to BAT and is essential for intravascular thermoregulation upon cold acclimation. This thermogenic capacity of PVAT plays an important protective role in the pathogenesis of atherosclerosis.

Background-Reactive oxygen species (ROS) play an important role in the maintenance of cardiovascular homeostasis. The present study sought to determine whether nuclear factor erythroid-2 related factor 2 (Nrf2), a master gene of the endogenous antioxidant defense system, is a critical regulator of the cardiac hypertrophic response to pathological stress. Methods and Results-Cardiac hypertrophy and dysfunction were established in mice by transverse aortic constriction (TAC). Nrf2 expression was transiently increased and then declined to the basal level while impairment of cardiac function proceeded. The knockout of Nrf2 (Nrf2 Ϫ/Ϫ ) did not cause any apparent structural and functional abnormalities in the unstressed heart. However, Nrf2Ϫ/Ϫ mice after TAC developed pathological cardiac hypertrophy, significant myocardial fibrosis and apoptosis, overt heart failure, and increased mortality, which were associated with elevated myocardial levels of 4-hydroxy-2-nonenal and 8-hydroxydeoxyguanosine and a complete blockade of the myocardial expression of several antioxidant genes. Overexpression of Nrf2 dramatically inhibited hypertrophic factor-induced ROS production and growth in both cardiomyocytes and cardiac fibroblasts, whereas knockdown of Nrf2 exerted opposite effects in both cells.Conclusions-These findings demonstrate that activation of Nrf2 provides a novel mechanism to protect the murine heart against pathological cardiac hypertrophy and heart failure via suppressing oxidative stress. Key Words: antioxidants Ⅲ apoptosis Ⅲ cardiomyopathies Ⅲ hypertrophy Ⅲ Nrf2 I n response to stress from neurohumoral activation, hypertension, or other myocardial injury, the heart initially compensates with an adaptive enlargement of the myocardium (ie, cardiac hypertrophy that is characterized by an increase in the size of individual cardiac myocytes and whole-organ mass). However, sustained cardiac hypertrophy is detrimental and leads to stroke, heart failure, and sudden death. [1][2][3] The latest epidemiological data has revealed that cardiac hypertrophy is a major predictor of heart failure, with a mortality as high as 80% for men and 70% for women within 8 years. 4 Despite the prominent contribution of cardiac hypertrophy to heart failure, the molecular mechanisms responsible for the transition from compensated hypertrophy to failure are poorly understood.It is firmly established that oxidative stress plays a causative role in the pathogenesis of cardiovascular disease including pathological cardiac hypertrophy and heart failure. 5-10 Surprisingly, larger clinical trials have shown that ROS scavengers of antioxidant vitamins for treatment of cardiovascular disease are ineffective or even harmful. [5][6][7][8] Because these studies have not examined hypertrophic heart disease or heart failure per se, additional studies with specific targeting of the source of oxidative stress or enhancing intrinsic antioxidant pathways are needed. Such studies will not only further extend our understanding of the role of oxidative stress b...

alpha-Tocopherol modulates two major signal transduction pathways centered on protein kinase C and phosphatidylinositol 3-kinase. Changes in the activity of these key kinases are associated with changes in cell proliferation, platelet aggregation, and NADPH-oxidase activation. Several genes are also regulated by tocopherols partly because of the effects of tocopherol on these two kinases, but also independently of them. These genes can be divided in five groups: Group 1. Genes that are involved in the uptake and degradation of tocopherols: alpha-tocopherol transfer protein, cytochrome P450 (CYP3A), gamma-glutamyl-cysteine synthetase heavy subunit, and glutathione-S-transferase. Group 2. Genes that are implicated with lipid uptake and atherosclerosis: CD36, SR-BI, and SR-AI/II. Group 3. Genes that are involved in the modulation of extracellular proteins: tropomyosin, collagen-alpha-1, MMP-1, MMP-19, and connective tissue growth factor. Group 4. Genes that are connected to adhesion and inflammation: E-selectin, ICAM-1 integrins, glycoprotein IIb, IL-2, IL-4, IL-1b, and transforming growth factor-beta (TGF-beta). Group 5. Genes implicated in cell signaling and cell cycle regulation: PPAR-gamma, cyclin D1, cyclin E, Bcl2-L1, p27, CD95 (APO-1/Fas ligand), and 5a-steroid reductase type 1. The transcription of p27, Bcl2, alpha-tocopherol transfer protein, cytochrome P450 (CYP3A), gamma-glutamyl-cysteine sythetase heavy subunit, tropomyosin, IL-2, and CTGF appears to be upregulated by one or more tocopherols. All the other listed genes are downregulated. Gene regulation by tocopherols has been associated with protein kinase C because of its deactivation by alpha-tocopherol and its contribution in the regulation of a number of transcription factors (NF-kappaB, AP1). A direct participation of the pregnane X receptor (PXR) / retinoid X receptor (RXR) has been also shown. The antioxidant-responsive element (ARE) and the TGF-beta-responsive element (TGF-beta-RE) appear in some cases to be implicated as well.

Nonalcoholic fatty liver disease (NAFLD) including nonalcoholic steatohepatitis (NASH) has reached epidemic proportions with no pharmacological therapy approved. Lower circulating glycine is consistently reported in patients with NAFLD, but the causes for reduced glycine, its role as a causative factor, and its therapeutic potential remain unclear. We performed transcriptomics in livers from humans and mice with NAFLD and found suppression of glycine biosynthetic genes, primarily alanine-glyoxylate aminotransferase 1 (AGXT1). Genetic (Agxt1−/− mice) and dietary approaches to limit glycine availability resulted in exacerbated diet-induced hyperlipidemia and steatohepatitis, with suppressed mitochondrial/peroxisomal fatty acid β-oxidation (FAO) and enhanced inflammation as the underlying pathways. We explored glycine-based compounds with dual lipid/glucose-lowering properties as potential therapies for NAFLD and identified a tripeptide (Gly-Gly-L-Leu, DT-109) that improved body composition and lowered circulating glucose, lipids, transaminases, proinflammatory cytokines, and steatohepatitis in mice with established NASH induced by a high-fat, cholesterol, and fructose diet. We applied metagenomics, transcriptomics, and metabolomics to explore the underlying mechanisms. The bacterial genus Clostridium sensu stricto was markedly increased in mice with NASH and decreased after DT-109 treatment. DT-109 induced hepatic FAO pathways, lowered lipotoxicity, and stimulated de novo glutathione synthesis. In turn, inflammatory infiltration and hepatic fibrosis were attenuated via suppression of NF-κB target genes and TGFβ/SMAD signaling. Unlike its effects on the gut microbiome, DT-109 stimulated FAO and glutathione synthesis independent of NASH. In conclusion, impaired glycine metabolism may play a causative role in NAFLD. Glycine-based treatment attenuates experimental NAFLD by stimulating hepatic FAO and glutathione synthesis, thus warranting clinical evaluation.

Nitroalkenes, the nitration products of unsaturated fatty acids formed via NO-dependent oxidative reactions, have been demonstrated to exert strong biological actions in endothelial cells and monocytes/macrophages; however, little is known about their effects on vascular smooth muscle cells (VSMCs). The present study examined the role of nitro-linoleic acid (LNO(2)) in the regulation of VSMC proliferation. We observed that LNO(2) inhibited VSMC proliferation in a dose-dependent manner. In addition, LNO(2) induced growth arrest of VSMCs in the G(1)/S phase of the cell cycle with an upregulation of the cyclin-dependent kinase inhibitor p27(kip1). Furthermore, LNO(2) triggered nuclear factor-erythroid 2-related factor 2 (Nrf2) nuclear translocation and activation of the antioxidant-responsive element-driven transcriptional activity via impairing Kelch-like ECH-associating protein 1 (Keap1)-mediated negative control of Nrf2 activity in VSMCs. LNO(2) upregulated the expression of Nrf2 protein levels, but not mRNA levels, in VSMCs. A forced activation of Nrf2 led to an upregulation of p27(kip1) and growth inhibition of VSMCs. In contrast, knock down of Nrf2 using an Nrf2 siRNA approach reversed the LNO(2)-induced upregulation of p27(kip1) and inhibition of cellular proliferation in VSMCs. These studies provide the first evidence that nitroalkene LNO(2) inhibits VSMC proliferation through activation of the Keap1/Nrf2 signaling pathway, suggesting an important role of nitroalkenes in vascular biology.

These studies demonstrate that acute administration of nitro-fatty acids is effective to reduce vascular inflammation in vivo. These findings reveal a direct role of nitro-fatty acids in the disruption of the TLR4 signalling complex in lipid rafts, upstream events of the NF-κB pathway, leading to resolution of pro-inflammatory activation of NF-κB in the vasculature.

Rationale: Nitro-oleic acid (OA-NO 2 ) is a bioactive, nitric-oxide derived fatty acid with physiologically relevant vasculoprotective properties in vivo. OA-NO 2 exerts cell signaling actions as a result of its strong electrophilic nature and mediates pleiotropic cell responses in the vasculature. Objective: The present study sought to investigate the protective role of OA-NO 2 in angiotensin (Ang) II–induced hypertension. Methods and Results: We show that systemic administration of OA-NO 2 results in a sustained reduction of Ang II–induced hypertension in mice and exerts a significant blood pressure lowering effect on preexisting hypertension established by Ang II infusion. OA-NO 2 significantly inhibits Ang II contractile response as compared to oleic acid (OA) in mesenteric vessels. The improved vasoconstriction is specific for the Ang II type 1 receptor (AT 1 R)-mediated signaling because vascular contraction by other G-protein–coupled receptors is not altered in response to OA-NO 2 treatment. From the mechanistic viewpoint, OA-NO 2 lowers Ang II–induced hypertension independently of peroxisome proliferation-activated receptor (PPAR)γ activation. Rather, OA-NO 2 , but not OA, specifically binds to the AT 1 R, reduces heterotrimeric G-protein coupling, and inhibits IP 3 (inositol-1,4,5-trisphosphate) and calcium mobilization, without inhibiting Ang II binding to the receptor. Conclusions: These results demonstrate that OA-NO 2 diminishes the pressor response to Ang II and inhibits AT 1 R-dependent vasoconstriction, revealing OA-NO 2 as a novel antagonist of Ang II–induced hypertension.

Several genes are regulated by tocopherols which can be categorized, based on their function, into five groups: genes that are involved in the uptake and degradation of tocopherols (Group