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      Selective peroxisome proliferator‐activated receptor‐α modulator K‐877 efficiently activates the peroxisome proliferator‐activated receptor‐α pathway and improves lipid metabolism in mice

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          Abstract

          Aims/Introduction

          Peroxisome proliferator‐activated receptor‐α ( PPARα) is a therapeutic target for hyperlipidemia. K‐877 is a new selective PPARα modulator ( SPPARMα) that activates PPARα transcriptional activity. The aim of the present study was to assess the effects of K‐877 on lipid metabolism in vitro and in vivo compared with those of classical PPARα agonists.

          Materials and Methods

          To compare the effects of K‐877 on PPARα transcriptional activity with those of the classical PPARα agonists Wy14643 (Wy) and fenofibrate (Feno), the cell‐based PPARα transactivation luciferase assay was carried out. WT and Ppara −/− mice were fed with a moderate‐fat (MF) diet for 6 days, and methionine–choline‐deficient (MCD) diet for 4 weeks containing Feno or K‐877.

          Results

          In luciferase assays, K‐877 activated PPARα transcriptional activity more efficiently than the classical PPARα agonists Feno and Wy. After being fed MF diet containing 0.001% K‐877 or 0.2% Feno for 6 days, mice in the K‐877 group showed significant increases in the expression of Ppara and its target genes, leading to marked reductions in plasma triglyceride levels compared with those observed in Feno‐treated animals. These K‐877 effects were blunted in Ppara −/− mice, confirming that K‐877 activates PPARα. In further experiments, K‐877 (0.00025%) and Feno (0.1%) equally improved the pathology of MCD diet‐induced non‐alcoholic fatty liver disease, with increased expression of hepatic fatty acid oxidation genes.

          Conclusions

          The present data show that K‐877 is an attractive PPARα‐modulating drug and can efficiently reduce plasma triglyceride levels, thereby alleviating the dysregulation of lipid metabolism.

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          Most cited references13

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          TLR activation of the transcription factor XBP1 regulates innate immune responses in macrophages.

          Sensors of pathogens, such as Toll-like receptors (TLRs), detect microbes to activate transcriptional programs that orchestrate adaptive responses to specific insults. Here we report that TLR4 and TLR2 specifically activated the endoplasmic reticulum (ER) stress sensor kinase IRE1alpha and its downstream target, the transcription factor XBP1. Previously described ER-stress target genes of XBP1 were not induced by TLR signaling. Instead, TLR-activated XBP1 was required for optimal and sustained production of proinflammatory cytokines in macrophages. Consistent with that finding, activation of IRE1alpha by ER stress acted in synergy with TLR activation for cytokine production. Moreover, XBP1 deficiency resulted in a much greater bacterial burden in mice infected with the TLR2-activating human intracellular pathogen Francisella tularensis. Our findings identify an unsuspected critical function for XBP1 in mammalian host defenses.
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            Central role of PPARalpha-dependent hepatic lipid turnover in dietary steatohepatitis in mice.

            We have proposed that steatohepatitis results from reactive oxygen species (ROS) acting on accumulated fatty acids to form proinflammatory lipoperoxides. Cytochrome P450 4a (Cyp4a) and Cyp2e1 are potential hepatic sources of ROS. We tested the hypothesis that increasing Cyp4a through activation of peroxisome proliferator-activated receptor alpha (PPARalpha) should aggravate steatohepatitis produced by feeding a methionine and choline deficient (MCD) diet. Conversely, we assessed dietary steatohepatitis in PPARalpha(-/-) mice that cannot up-regulate Cyp4a. Male wild type (wt) or PPARalpha(-/-) mice (C57BL6 background) were fed the MCD diet with or without Wy-14,643 (0.1% wt/wt), a potent PPARalpha agonist. Controls were fed the same diet supplemented with methionine and choline. After 5 weeks, wt mice fed the MCD diet developed moderate steatohepatitis and alanine aminotransferase (ALT) levels were increased. Wy-14,643 prevented rather than increased liver injury; ALT levels were only mildly elevated whereas steatohepatitis was absent. Wy-14,643 up-regulated mRNA for liver fatty acid binding protein and peroxisomal beta-oxidation enzymes (acyl-CoA oxidase, bifunctional enzyme, and ketothiolase), thereby reducing hepatic triglycerides and preventing steatosis. In wt mice, dietary feeding up-regulated Cyp4a14 mRNA 2.7-fold and increased hepatic lipoperoxides compared with controls. Wy-14,643 prevented hepatic lipoperoxides from accumulating despite an 18-fold increase in both Cyp4a10 and Cyp4a14 mRNA. PPARalpha(-/-) mice fed the MCD diet developed more severe steatohepatitis than wt mice, and were unaffected by Wy-14,643. In conclusion, PPARalpha activation both increases Cyp4a expression and enhances hepatic lipid turnover; the latter effect removes fatty acids as substrate for lipid peroxidation and is sufficiently powerful to prevent the development of dietary steatohepatitis.
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              Selective peroxisome proliferator-activated receptorα modulators (SPPARMα): The next generation of peroxisome proliferator-activated receptor α-agonists

              Dyslipidemia is a major risk factor for cardiovascular (CV) disease – the primary cause of death, worldwide. Although reducing levels of low-density lipoprotein-cholesterol can significantly reduce CV risk, a high level of residual risk persists, especially in people with obesity-related conditions, such as metabolic syndrome and type 2 diabetes mellitus. Peroxisome proliferator-activated receptor alpha- (PPARα-) agonists (e.g. fibrates), play a central role in the reduction of macro- and microvascular risk in these patients. However, the currently available fibrates are weak (PPARα-agonists) with limited efficacy due to dose-related adverse effects. To address this problem, a new generation of highly potent and selective PPARα-modulators (SPPARMα) is being developed that separate the benefits of the PPARα-agonists from their unwanted side effects. Among these, aleglitazar (a dual PPARα/γ agonist) and GFT505 (a dual PPAR α/δ agonist) have recently entered late-phase development. Although both compounds are more potent PPARα-activators than fenofibrate in vitro, only aleglitezar is more effective in lowering triglycerides and raising high-density lipoprotein-cholesterol (HDL-C) in humans. However, it is also associated with a potential risk of adverse effects. More recently, a highly potent, specific PPARα-agonist (K-877) has emerged with SPPARMα characteristics. Compared to fenofibrate, K-877 has more potent PPARα-activating efficacy in vitro, greater effects on triglycerides- and HDL-C levels in humans, and a reduced risk of adverse effects. If successful, K-877 has the potential to supersede the fibrates as the treatment of choice for patients with residual CV risk associated with metabolic syndrome and type 2 diabetes.
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                Author and article information

                Contributors
                hshimano@md.tsukuba.ac.jp
                Journal
                J Diabetes Investig
                J Diabetes Investig
                10.1111/(ISSN)2040-1124
                JDI
                Journal of Diabetes Investigation
                John Wiley and Sons Inc. (Hoboken )
                2040-1116
                2040-1124
                25 April 2017
                July 2017
                : 8
                : 4 ( doiID: 10.1111/jdi.2017.8.issue-4 )
                : 446-452
                Affiliations
                [ 1 ] Department of Internal Medicine (Endocrinology and Metabolism) Faculty of MedicineUniversity of Tsukuba Tsukuba IbarakiJapan
                [ 2 ] International Institute for Integrative Sleep Medicine (WPI‐IIIS)University of Tsukuba Tsukuba IbarakiJapan
                [ 3 ] Life Science Center Tsukuba Advanced Research Alliance (TARA)University of Tsukuba Tsukuba IbarakiJapan
                Author notes
                [*] [* ] Correspondence

                Hitoshi Shimano

                Tel.: +81‐29‐853‐3053

                Fax: +81‐29‐853‐3174

                E‐mail address: hshimano@ 123456md.tsukuba.ac.jp

                Article
                JDI12621
                10.1111/jdi.12621
                5497046
                28084058
                3d872979-6cf8-4d18-8e5c-599c7a73b7c4
                © 2017 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd

                This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

                History
                : 18 September 2016
                : 21 December 2016
                : 10 January 2017
                Page count
                Figures: 4, Tables: 0, Pages: 7, Words: 3762
                Funding
                Funded by: JSPS KAKENHI
                Award ID: 16H03253
                Categories
                Original Article
                Articles
                Basic Science and Research
                Custom metadata
                2.0
                jdi12621
                July 2017
                Converter:WILEY_ML3GV2_TO_NLMPMC version:5.1.2 mode:remove_FC converted:05.07.2017

                lipid metabolism,peroxisome proliferator‐activated receptor‐α,selective peroxisome proliferator‐activated receptor‐α modulator

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