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Jain M, Plutzky J. Commentary. Clin Chem 2012; 58:829-30. [DOI: 10.1373/clinchem.2012.182139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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103
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Shetty S, Ramos-Roman MA, Cho YR, Brown J, Plutzky J, Muise ES, Horton JD, Scherer PE, Parks EJ. Enhanced fatty acid flux triggered by adiponectin overexpression. Endocrinology 2012; 153:113-22. [PMID: 22045665 PMCID: PMC3249680 DOI: 10.1210/en.2011-1339] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 09/30/2011] [Indexed: 12/30/2022]
Abstract
Adiponectin overexpression in mice increases insulin sensitivity independent of adiposity. Here, we combined stable isotope infusion and in vivo measurements of lipid flux with transcriptomic analysis to characterize fatty acid metabolism in transgenic mice that overexpress adiponectin via the aP2-promoter (ADNTg). Compared with controls, fasted ADNTg mice demonstrated a 31% reduction in plasma free fatty acid concentrations (P = 0.008), a doubling of ketones (P = 0.028), and a 68% increase in free fatty acid turnover in plasma (15.1 ± 1.5 vs. 25.3 ± 6.8 mg/kg · min, P = 0.011). ADNTg mice had 2-fold more brown adipose tissue mass, and triglyceride synthesis and turnover were 5-fold greater in this organ (P = 0.046). Epididymal white adipose tissue was slightly reduced, possibly due to the approximately 1.5-fold increase in the expression of genes involved in oxidation (peroxisome proliferator-activated receptor α, peroxisome proliferator-activated receptor-γ coactivator 1α, and uncoupling protein 3). In ADNTg liver, lipogenic gene expression was reduced, but there was an unexpected increase in the expression of retinoid pathway genes (hepatic retinol binding protein 1 and retinoic acid receptor beta and adipose Cyp26A1) and liver retinyl ester content (64% higher, P < 0.02). Combined, these data support a physiological link between adiponectin signaling and increased efficiency of triglyceride synthesis and hydrolysis, a process that can be controlled by retinoids. Interactions between adiponectin and retinoids may underlie adiponectin's effects on intermediary metabolism.
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Skentzos S, Shubina M, Plutzky J, Turchin A. Structured vs. unstructured: factors affecting adverse drug reaction documentation in an EMR repository. AMIA ... ANNUAL SYMPOSIUM PROCEEDINGS. AMIA SYMPOSIUM 2011; 2011:1270-1279. [PMID: 22195188 PMCID: PMC3243255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Adverse reactions to medications to which the patient was known to be intolerant are common. Electronic decision support can prevent them but only if history of adverse reactions to medications is recorded in structured format. We have conducted a retrospective study of 31,531 patients with adverse reactions to statins documented in the notes, as identified with natural language processing. The software identified statin adverse reactions with sensitivity of 86.5% and precision of 91.9%. Only 9020 of these patients had an adverse reaction to a statin recorded in structured format. In multivariable analysis the strongest predictor of structured documentation was utilization of EMR functionality that integrated the medication list with the structured medication adverse reaction repository (odds ratio 48.6, p < 0.0001). Integration of information flow between EMR modules can help improve documentation and potentially prevent adverse drug events.
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105
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Shabrova EV, Tarnopolsky O, Singh AP, Plutzky J, Vorsa N, Quadro L. Insights into the molecular mechanisms of the anti-atherogenic actions of flavonoids in normal and obese mice. PLoS One 2011; 6:e24634. [PMID: 22016761 PMCID: PMC3189911 DOI: 10.1371/journal.pone.0024634] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 08/17/2011] [Indexed: 01/02/2023] Open
Abstract
Obesity is a major and independent risk factor for cardiovascular disease and it is strongly associated with the development of dyslipidemia, insulin resistance and type 2 diabetes. Flavonoids, a diverse group of polyphenol compounds of plant origin widely distributed in human diet, have been reported to have numerous health benefits, although the mechanisms underlying these effects have remained obscure. We analyzed the effects of chronic dietary supplementation with flavonoids extracted from cranberry (FLS) in normal and obese C57/BL6 mice compared to mice maintained on the same diets lacking FLS. Obese mice supplemented with flavonoids showed an amelioration of insulin resistance and plasma lipid profile, and a reduction of visceral fat mass. We provide evidence that the adiponectin-AMPK pathway is the main mediator of the improvement of these metabolic disorders. In contrast, the reduced plasma atherogenic cholesterol observed in normal mice under FLS seems to be due to a downregulation of the hepatic cholesterol synthesis pathway. Overall, we demonstrate for the first time that the molecular mechanisms underlying the beneficial effects of flavonoids are determined by the metabolic state.
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106
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Blaser BW, Kim HT, Alyea EP, Ho VT, Cutler C, Armand P, Koreth J, Antin JH, Plutzky J, Soiffer RJ. Hyperlipidemia and statin use after allogeneic hematopoietic stem cell transplantation. Biol Blood Marrow Transplant 2011; 18:575-83. [PMID: 21839706 DOI: 10.1016/j.bbmt.2011.08.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 08/01/2011] [Indexed: 12/18/2022]
Abstract
An increased incidence of cardiovascular complications has been documented in recipients of allogeneic hematopoietic stem cell transplantation (HSCT). Despite this, little is known about the risk factors for hyperlipidemia or the role of lipid-lowering therapy early after transplantation. We performed a retrospective analysis of all patients who underwent allogeneic HSCT at the Dana-Farber Cancer Institute from 1998 to 2008 and who survived more than 100 days. The incidence of hypercholesterolemia and hypertriglyceridemia in the first 2 years after transplantation was 73.4% and 72.5%, respectively. In multivariable analysis, the development of acute graft-versus-host disease was independently associated with both hypercholesterolemia (odds ratio [OR] = 1.62) and hypertriglyceridemia (OR = 1.54) after transplantation. Statin use was instituted in 29% of patients and was associated with a significant net reduction in total cholesterol (65 mg/dL, P < .0001), triglyceride (118 mg/dL P < .0001), and LDL levels (59 mg/dL P < .0001) without any significant adverse effects. These data suggest that hyperlipidemia is common in the first 2 years after allogeneic transplantation when most patients remain under the care of the transplantation physician and lipid-lowering therapy may be underutilized. Given the cardiovascular risk associated with hyperlipidemia and the tolerability of statins, further prospective evaluation of lipid abnormalities and their treatment seems well warranted.
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107
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Davidson MH, Plutzky J. The role of cardiologists in the management of patients with diabetes is evolving owing to the close relationship between diabetes and CAD. Introduction. Am J Cardiol 2011; 108:1B-2B. [PMID: 21802576 DOI: 10.1016/j.amjcard.2011.03.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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108
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Abstract
Type 2 diabetes has long been recognized as an independent risk factor for cardiovascular disease (CVD), including coronary artery disease (CAD), stroke, peripheral arterial disease, cardiomyopathy, and congestive heart failure. Cardiovascular (CV) complications are the leading cause of comorbidity and death in the patient with diabetes. Vascular complications of diabetes also extend to microvascular disease, manifest as diabetic nephropathy, neuropathy, and retinopathy. The impact of glycemic control in reducing microvascular complications is well established. Although more controversial, there is also evidence that glycemic control can limit macrovascular disease, including CAD, peripheral arterial disease, and stroke. Glycemic control in the context of type 2 diabetes, as well as prediabetes, is also intertwined with CV risk factors such as obesity, hypertriglyceridemia, and blood pressure control. Similarly, major issues and concerns have arisen around the CV safety of antidiabetic therapy. Together, these issues have focused attention on the need to understand the CV effects of current treatments for type 2 diabetes and the optimal strategies for care of patients with this disease.
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Kiefer FW, Neschen S, Pfau B, Legerer B, Neuhofer A, Kahle M, Hrabé de Angelis M, Schlederer M, Mair M, Kenner L, Plutzky J, Zeyda M, Stulnig TM. Osteopontin deficiency protects against obesity-induced hepatic steatosis and attenuates glucose production in mice. Diabetologia 2011; 54:2132-42. [PMID: 21562757 PMCID: PMC3131508 DOI: 10.1007/s00125-011-2170-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2010] [Accepted: 04/04/2011] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS Obesity is strongly associated with the development of non-alcoholic fatty liver disease (NAFLD). The cytokine osteopontin (OPN) was recently shown to be involved in obesity-induced adipose tissue inflammation and reduced insulin response. Accumulating evidence links OPN to the pathogenesis of NAFLD. Here we aimed to identify the role of OPN in obesity-associated hepatic steatosis and impaired hepatic glucose metabolism. METHODS Wild-type (WT) and Opn (also known as Spp1) knockout (Opn (-/-)) mice were fed a high-fat or low-fat diet to study OPN effects in obesity-driven hepatic alterations. RESULTS We show that genetic OPN deficiency protected from obesity-induced hepatic steatosis, at least in part, by downregulating hepatic triacylglycerol synthesis. Conversely, absence of OPN promoted fat storage in adipose tissue thereby preventing the obesity-induced shift to ectopic fat accumulation in the liver. Euglycaemic-hyperinsulinaemic clamp studies revealed that insulin resistance and excess hepatic glucose production in obesity were significantly attenuated in Opn (-/-) mice. OPN deficiency markedly improved hepatic insulin signalling as shown by enhanced insulin receptor substrate-2 phosphorylation and prevented upregulation of the major hepatic transcription factor Forkhead box O1 and its gluconeogenic target genes. In addition, obesity-driven hepatic inflammation and macrophage accumulation was blocked by OPN deficiency. CONCLUSIONS/INTERPRETATION Our data strongly emphasise OPN as mediator of obesity-associated hepatic alterations including steatosis, inflammation, insulin resistance and excess gluconeogenesis. Targeting OPN action could therefore provide a novel therapeutic strategy to prevent obesity-related complications such as NAFLD and type 2 diabetes.
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110
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Rhee EJ, Nallamshetty S, Plutzky J. Retinoid metabolism and its effects on the vasculature. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:230-40. [PMID: 21810483 DOI: 10.1016/j.bbalip.2011.07.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/15/2011] [Accepted: 07/06/2011] [Indexed: 12/16/2022]
Abstract
Retinoids, the metabolically-active structural derivatives of vitamin A, are critical signaling molecules in many fundamental biological processes including cell survival, proliferation and differentiation. Emerging evidence, both clinical and molecular, implicates retinoids in atherosclerosis and other vasculoproliferative disorders such as restenosis. Although the data from clinical trials examining effect of vitamin A and vitamin precursors on cardiac events have been contradictory, this data does suggest that retinoids do influence fundamental processes relevant to atherosclerosis. Preclinical animal model and cellular studies support these concepts. Retinoids exhibit complex effects on proliferation, growth, differentiation and migration of vascular smooth muscle cells (VSMC), including responses to injury and atherosclerosis. Retinoids also appear to exert important inhibitory effects on thrombosis and inflammatory responses relevant to atherogenesis. Recent studies suggest retinoids may also be involved in vascular calcification and endothelial function, for example, by modulating nitric oxide pathways. In addition, established retinoid effects on lipid metabolism and adipogenesis may indirectly influence inflammation and atherosclerosis. Collectively, these observations underscore the scope and complexity of retinoid effects relevant to vascular disease. Additional studies are needed to elucidate how context and metabolite-specific retinoid effects affect atherosclerosis. This article is part of a Special Issue entitled: Retinoid and Lipid Metabolism.
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111
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Brown JD, Oligino E, Rader DJ, Saghatelian A, Plutzky J. VLDL hydrolysis by hepatic lipase regulates PPARδ transcriptional responses. PLoS One 2011; 6:e21209. [PMID: 21750705 PMCID: PMC3130023 DOI: 10.1371/journal.pone.0021209] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 05/23/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND PPARs (α,γ,δ) are a family of ligand-activated transcription factors that regulate energy balance, including lipid metabolism. Despite these critical functions, the integration between specific pathways of lipid metabolism and distinct PPAR responses remains obscure. Previous work has revealed that lipolytic pathways can activate PPARs. Whether hepatic lipase (HL), an enzyme that regulates VLDL and HDL catabolism, participates in PPAR responses is unknown. METHODS/PRINCIPAL FINDINGS Using PPAR ligand binding domain transactivation assays, we found that HL interacted with triglyceride-rich VLDL (>HDL≫LDL, IDL) to activate PPARδ preferentially over PPARα or PPARγ, an effect dependent on HL catalytic activity. In cell free ligand displacement assays, VLDL hydrolysis by HL activated PPARδ in a VLDL-concentration dependent manner. Extended further, VLDL stimulation of HL-expressing HUVECs and FAO hepatoma cells increased mRNA expression of canonical PPARδ target genes, including adipocyte differentiation related protein (ADRP), angiopoietin like protein 4 and pyruvate dehydrogenase kinase-4. HL/VLDL regulated ADRP through a PPRE in the promoter region of this gene. In vivo, adenoviral-mediated hepatic HL expression in C57BL/6 mice increased hepatic ADRP mRNA levels by 30%. In ob/ob mice, a model with higher triglycerides than C57BL/6 mice, HL overexpression increased ADRP expression by 70%, demonstrating the importance of triglyceride substrate for HL-mediated PPARδ activation. Global metabolite profiling identified HL/VLDL released fatty acids including oleic acid and palmitoleic acid that were capable of recapitulating PPARδ activation and ADRP gene regulation in vitro. CONCLUSIONS These data define a novel pathway involving HL hydrolysis of VLDL that activates PPARδ through generation of specific monounsaturated fatty acids. These data also demonstrate how integrating cell biology with metabolomic approaches provides insight into specific lipid mediators and pathways of lipid metabolism that regulate transcription.
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Lee JH, Giannikopoulos P, Duncan SA, Wang J, Johansen CT, Brown JD, Plutzky J, Hegele RA, Glimcher LH, Lee AH. The transcription factor cyclic AMP-responsive element-binding protein H regulates triglyceride metabolism. Nat Med 2011; 17:812-5. [PMID: 21666694 DOI: 10.1038/nm.2347] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Accepted: 03/07/2011] [Indexed: 12/16/2022]
Abstract
Here we report that the transcription factor cyclic AMP-responsive element-binding protein H (CREB-H, encoded by CREB3L3) is required for the maintenance of normal plasma triglyceride concentrations. CREB-H-deficient mice showed hypertriglyceridemia secondary to inefficient triglyceride clearance catalyzed by lipoprotein lipase (Lpl), partly due to defective expression of the Lpl coactivators Apoc2, Apoa4 and Apoa5 (encoding apolipoproteins C2, A4 and A5, respectively) and concurrent augmentation of the Lpl inhibitor Apoc3. We identified multiple nonsynonymous mutations in CREB3L3 that produced hypomorphic or nonfunctional CREB-H protein in humans with extreme hypertriglyceridemia, implying a crucial role for CREB-H in human triglyceride metabolism.
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Abstract
The peroxisome proliferator-activated receptors (PPARs) and the retinoid X receptors (RXRs) are ligand-activated transcription factors that coordinately regulate gene expression. This PPAR-RXR transcriptional complex plays a critical role in energy balance, including triglyceride metabolism, fatty acid handling and storage, and glucose homeostasis: processes whose dysregulation characterize obesity, diabetes, and atherosclerosis. PPARs and RXRs are also involved directly in inflammatory and vascular responses in endothelial and vascular smooth muscle cells. New insights into fundamental aspects of PPAR and RXR biology, and their actions in the vasculature, continue to appear. Although RXRs are obligate heterodimeric partners for PPAR action, the part that RXRs, and their endogenous retinoid mediators, exert in the vessel wall is less well understood. Biological insights into PPAR-RXRs may help inform interpretation of clinical trials with synthetic PPAR agonists and prospects for future PPAR therapeutics. Importantly, the extensive data establishing a key role for PPARs and RXRs in energy balance, inflammation, and vascular biology stands separately from the clinical experience with any given synthetic PPAR agonist. Both the basic science data and the clinical experience with PPAR agonists identify the need to better understand these important transcriptional regulators.
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Chang K, Francis SA, Aikawa E, Figueiredo JL, Kohler RH, McCarthy JR, Weissleder R, Plutzky J, Jaffer FA. Pioglitazone suppresses inflammation in vivo in murine carotid atherosclerosis: novel detection by dual-target fluorescence molecular imaging. Arterioscler Thromb Vasc Biol 2010; 30:1933-9. [PMID: 20689078 DOI: 10.1161/atvbaha.110.206342] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE To investigate the effects of pioglitazone (PIO), a peroxisome proliferator-activated receptor γ agonist, on plaque matrix metalloproteinase (MMP) and macrophage (Mac) responses in vivo in a molecular imaging study. METHODS AND RESULTS In vitro, PIO suppressed MMP-9 protein expression in murine peritoneal Macs (P<0.05). To assess PIO's effects on plaque inflammation, nondiabetic apolipoprotein E(-/-) mice receiving a high-cholesterol diet (HCD) were administered an MMP-activatable fluorescence imaging agent and a spectrally distinct Mac-avid fluorescent nanoparticle. After 24 hours, mice underwent survival dual-target intravital fluorescence microscopy of carotid arterial plaques. These mice were then randomized to HCD or HCD plus 0.012% PIO for 8 weeks, followed by a second intravital fluorescence microscopy study of the same carotid plaque. In the HCD group, in vivo MMP and Mac target-to-background ratios increased similarly (P<0.01 versus baseline). In contrast, PIO reduced MMP and Mac target-to-background ratios (P<0.01) versus HCD. Changes in MMP and Mac signals correlated strongly (r ≥0.75). Microscopy demonstrated MMP and Mac reductions in PIO-treated mice and a PIO-modulated increase in plaque collagen. CONCLUSIONS Serial optical molecular imaging demonstrates that plaque MMP and Mac activity in vivo intensify with hypercholesterolemia and are reduced by PIO therapy.
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Fonseca VA, Zinman B, Nauck MA, Goldfine AB, Plutzky J. Confronting the type 2 diabetes epidemic: the emerging role of incretin-based therapies. Am J Med 2010; 123:S2-S10. [PMID: 20609666 DOI: 10.1016/j.amjmed.2010.04.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This report highlights a roundtable discussion that occurred during the annual meeting of the International Diabetes Federation (IDF) in November 2009, in Montreal, Quebec, Canada. Participants included Bernard Zinman, MD, Michael A. Nauck, MD, PhD, Jorge Plutzky, MD, and Allison B. Goldfine, MD. The roundtable was chaired by Vivian A. Fonseca, MD. Among the topics discussed were the burden of type 2 diabetes mellitus and the importance of "appropriate therapy," which includes not only managing glycemia but also the management of concomitant risk factors such as hypertension and dyslipidemia. The discussants also identified issues that remain to be resolved, such as determining the nature of first-line therapy (e.g., should initial dual-agent therapy be encouraged?) and agreeing upon the most appropriate agent to be combined with metformin, which is the current standard of care. Among the new treatments discussed for type 2 diabetes were the analogues of the incretin hormones glucagonlike peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), namely, the GLP-1 receptor agonists-as well as the inhibitors of dipeptidyl peptidase-4 (DPP-4), the enzyme that regulates the bioactivity of the endogenous incretin hormones. These agents have some interesting advantages; not only do they effectively lower glucose, but they also have demonstrated beneficial metabolic and cardiovascular effects. Particularly with respect to the GIP and GLP-1, weight loss, blood pressure reductions, and beta-cell function improvements have been observed in clinical trials. What remains to be determined, by means of additional clinical experience and perhaps additional head-to-head trials, are the long-term benefits of GLP-1 receptor agonists and DPP-4 inhibitors and the sorts of roles these 2 classes of agents may play in the type 2 diabetes therapeutic continuum.
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Chutkow WA, Birkenfeld AL, Brown JD, Lee HY, Frederick DW, Yoshioka J, Patwari P, Kursawe R, Cushman SW, Plutzky J, Shulman GI, Samuel VT, Lee RT. Deletion of the alpha-arrestin protein Txnip in mice promotes adiposity and adipogenesis while preserving insulin sensitivity. Diabetes 2010; 59:1424-34. [PMID: 20299477 PMCID: PMC2874703 DOI: 10.2337/db09-1212] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
OBJECTIVE Thioredoxin interacting protein (Txnip), a regulator of cellular oxidative stress, is induced by hyperglycemia and inhibits glucose uptake into fat and muscle, suggesting a role for Txnip in type 2 diabetes pathogenesis. Here, we tested the hypothesis that Txnip-null (knockout) mice are protected from insulin resistance induced by a high-fat diet. RESEARCH DESIGN AND METHODS Txnip gene-deleted (knockout) mice and age-matched wild-type littermate control mice were maintained on a standard chow diet or subjected to 4 weeks of high-fat feeding. Mice were assessed for body composition, fat development, energy balance, and insulin responsiveness. Adipogenesis was measured from ex vivo fat preparations, and in mouse embryonic fibroblasts (MEFs) and 3T3-L1 preadipocytes after forced manipulation of Txnip expression. RESULTS Txnip knockout mice gained significantly more adipose mass than controls due to a primary increase in both calorie consumption and adipogenesis. Despite increased fat mass, Txnip knockout mice were markedly more insulin sensitive than controls, and augmented glucose transport was identified in both adipose and skeletal muscle. RNA interference gene-silenced preadipocytes and Txnip(-/-) MEFs were markedly adipogenic, whereas Txnip overexpression impaired adipocyte differentiation. As increased adipogenesis and insulin sensitivity suggested aspects of augmented peroxisome proliferator-activated receptor-gamma (PPARgamma) response, we investigated Txnip's regulation of PPARgamma function; manipulation of Txnip expression directly regulated PPARgamma expression and activity. CONCLUSIONS Txnip deletion promotes adiposity in the face of high-fat caloric excess; however, loss of this alpha-arrestin protein simultaneously enhances insulin responsiveness in fat and skeletal muscle, revealing Txnip as a novel mediator of insulin resistance and a regulator of adipogenesis.
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Ruby MA, Goldenson B, Orasanu G, Johnston TP, Plutzky J, Krauss RM. VLDL hydrolysis by LPL activates PPAR-alpha through generation of unbound fatty acids. J Lipid Res 2010; 51:2275-81. [PMID: 20421589 DOI: 10.1194/jlr.m005561] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent evidence suggests that lipoproteins serve as circulating reservoirs of peroxisomal proliferator activated receptor (PPAR) ligands that are accessible through lipolysis. The present study was conducted to determine the biochemical basis of PPAR-alpha activation by lipolysis products and their contribution to PPAR-alpha function in vivo. PPAR-alpha activation was measured in bovine aortic endothelial cells following treatment with human plasma, VLDL lipolysis products, or oleic acid. While plasma failed to activate PPAR-alpha, oleic acid performed similarly to VLDL lipolysis products. Therefore, fatty acids are likely to be the PPAR-alpha ligands generated by VLDL lipolysis. Indeed, unbound fatty acid concentration determined PPAR-alpha activation regardless of fatty acid source, with PPAR-alpha activation occurring only at unbound fatty acid concentrations that are unachievable under physiological conditions without lipase action. In mice, a synthetic lipase inhibitor (poloxamer-407) attenuated fasting-induced changes in expression of PPAR-alpha target genes. Apolipoprotein CIII (apoCIII), an endogenous inhibitor of lipoprotein and hepatic lipase, regulated access to the lipoprotein pool of PPAR-alpha ligands, because addition of exogenous apoCIII inhibited, and removal of endogenous apoCIII potentiated, lipolytic PPAR-alpha activation. These data suggest that the PPAR-alpha response is generated by unbound fatty acids released locally by lipase activity and not by circulating plasma fatty acids.
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Brown J, Nallamshetty S, Plutzky J. Intersecting vectors of basic science research and clinical medicine: LOX-1? Clin Chem 2010; 56:499-501. [PMID: 20185618 DOI: 10.1373/clinchem.2009.142232] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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120
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Chang K, Francis S, Aikawa E, Figueiredo J, Patel P, Weissleder R, Plutzky J, Jaffer F. Abstract: P640 PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR-Γ ACTIVATION REDUCES INFLAMMATION IN ATHEROSCLEROSIS AS ASSESSED BY SERIAL IN VIVO FLUORESCENCE MOLECULAR IMAGING. ATHEROSCLEROSIS SUPP 2009. [DOI: 10.1016/s1567-5688(09)70808-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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121
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Plutzky J. Abstract: 511 THE RXR-PPAR COMPLEX IN THE REGULATION OF ENERGY BALANCE. ATHEROSCLEROSIS SUPP 2009. [DOI: 10.1016/s1567-5688(09)71612-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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122
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Orasanu G, Plutzky J. The pathologic continuum of diabetic vascular disease. J Am Coll Cardiol 2009; 53:S35-42. [PMID: 19179216 DOI: 10.1016/j.jacc.2008.09.055] [Citation(s) in RCA: 288] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Accepted: 09/30/2008] [Indexed: 12/22/2022]
Abstract
Hyperglycemia can promote vascular complications by multiple mechanisms, with formation of advanced glycation end products and increased oxidative stress proposed to contribute to both macrovascular and microvascular complications. Many of the earliest pathologic responses to hyperglycemia are manifest in the vascular cells that directly encounter elevated blood glucose levels. In the macrovasculature, these include endothelial cells and vascular smooth muscle cells. In the microvasculature, these include endothelial cells, pericytes (in retinopathy), and podocytes (in renal disease). Additionally, neovascularization arising from the vasa vasorum may promote atherosclerotic plaque progression and contribute to plaque rupture, thereby interconnecting macroangiopathy and microangiopathy.
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Fruchart JC, Sacks F, Hermans MP, Assmann G, Brown WV, Ceska R, Chapman MJ, Dodson PM, Fioretto P, Ginsberg HN, Kadowaki T, Lablanche JM, Marx N, Plutzky J, Reiner Z, Rosenson RS, Staels B, Stock JK, Sy R, Wanner C, Zambon A, Zimmet P. The Residual Risk Reduction Initiative: a call to action to reduce residual vascular risk in patients with dyslipidemia. Am J Cardiol 2009; 102:1K-34K. [PMID: 19068318 DOI: 10.1016/s0002-9149(08)01833-x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Despite achieving targets for low-density lipoprotein (LDL) cholesterol, blood pressure, and glycemia in accordance with current standards of care, patients with dyslipidemia remain at high residual risk of vascular events. Atherogenic dyslipidemia, characterized by elevated triglycerides and low levels of high-density lipoprotein (HDL) cholesterol, often with elevated apolipoprotein B and non-HDL cholesterol, is common in patients with established cardiovascular disease (CVD), type 2 diabetes mellitus, or metabolic syndrome and contributes to both macrovascular and microvascular residual risk. However, atherogenic dyslipidemia is largely underdiagnosed and undertreated in clinical practice. The Residual Risk Reduction Initiative (R3i) was established to address this highly relevant clinical issue. The aims of this position paper are (1) to highlight evidence that atherogenic dyslipidemia is associated with residual macrovascular and microvascular risk in patients at high risk for CVD, despite current standards of care for dyslipidemia and diabetes; and (2) to recommend therapeutic intervention for reducing this residual vascular risk supported by evidence and expert consensus. Lifestyle modification with nutrition and exercise is an important, effective, and underutilized first step in reducing residual vascular risk. Therapeutic intervention aimed at achievement of all lipid targets is also often required. Combination lipid-modifying therapy, with the addition of niacin, a fibrate, or omega-3 fatty acids to statin therapy, increases the probability of achieving all lipid goals. Outcomes studies are in progress to evaluate whether these combination treatment strategies translate to a clinical benefit greater than that achieved with statins alone. The R3i highlights the need to address with lifestyle and/or pharmacotherapy the high level of residual risk of CVD events and microvascular complications among patients with dyslipidemia receiving therapy for high levels of LDL cholesterol and for diabetes in accordance with current standards of care.
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Kanda T, Brown JD, Orasanu G, Vogel S, Gonzalez FJ, Sartoretto J, Michel T, Plutzky J. PPARgamma in the endothelium regulates metabolic responses to high-fat diet in mice. J Clin Invest 2008; 119:110-24. [PMID: 19065047 DOI: 10.1172/jci36233] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 11/05/2008] [Indexed: 01/22/2023] Open
Abstract
Although endothelial dysfunction, defined as abnormal vasoreactivity, is a common early finding in individuals with type 2 diabetes, the endothelium has not been known to regulate metabolism. As PPARgamma, a transcriptional regulator of energy balance, is expressed in endothelial cells, we set out to investigate the role of endothelial cell PPARgamma in metabolism using mice that lack PPARgamma in the endothelium and BM (gammaEC/BM-KO). When gammaEC/BM-KO mice were fed a high-fat diet, they had decreased adiposity and increased insulin sensitivity compared with control mice, despite increased serum FFA and triglyceride (TG) levels. After fasting or olive oil gavage, gammaEC/BM-KO mice exhibited significant dyslipidemia and failed to respond to the FFA and TG lowering effects of the PPARgamma agonist rosiglitazone. BM transplantation studies, which reconstituted hematopoietic PPARgamma, established that these metabolic phenotypes were due to endothelial PPARgamma deficiency. We further found that the impairment in TG-rich lipoprotein metabolism in gammaEC/BM-KO mice was associated with fatty acid-mediated lipoprotein lipase inhibition and changes in a PPARgamma-regulated endothelial cell transcriptional program. Despite their metabolic improvements, high-fat diet-fed gammaEC/BM-KO mice had impaired vasoreactivity. Taken together, these data suggest that PPARgamma in the endothelium integrates metabolic and vascular responses and may contribute to the effects of PPARgamma agonists, thus expanding what endothelial function and dysfunction may entail.
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Fruchart JC, Sacks F, Hermans MP, Assmann G, Brown WV, Ceska R, Chapman MJ, Dodson PM, Fioretto P, Ginsberg HN, Kadowaki T, Lablanche JM, Marx N, Plutzky J, Reiner Ž, Rosenson RS, Staels B, Stock JK, Sy R, Wanner C, Zambon A, Zimmet P. The Residual Risk Reduction Initiative: A Call to Action to Reduce Residual Vascular Risk in Patients with Dyslipidemia. Am J Cardiol 2008. [DOI: 10.1016/j.amjcard.2008.10.002] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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