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GRK 1482 Jahrbuch 2011-2014

Publications [1] Hotamisligil GS. Inflammation and metabolic disorders. Nature. 2006, 444: 860-867. [2] Cani PD, Bibiloni R, Knauf C, et al. Changes in gut micro- biota control metabolic endotoxemia-induced inflam- mation in high-fat diet-induced obesity and diabetes in mice. Diabetes. 2008, 57: 1470-1481. [3] Gruber L, Kisling S, …, Haller D. High fat diet accelerates pathogenesis of murine Crohn’s Disease-like ileitis inde- pendently of obesity. Submitted (Plos One). [4] Rath E, Berger E, …, Haller D. Induction of dsRNA-acti- vated protein kinase links mitochondrial unfolded pro- tein response to the pathogenesis of intestinal inflam- mation. Gut 2012, 61: 1269-1278. [5] Zhao Q, Wang J, Levichkin IV, et al. A mitochondrial spe- cific stress response in mammalian cells. Embo J 2002, 21: 4411-4419. change of fat source from palm oil to lard using different feed- ing periods. We will further identify possible variations in gene expression under HFD conditions described above using micro- array technology. To characterize the impact of HFD on gut and peripheral adipose tissue in the context of UPR we will establish adiponectin- and gut-specific conditional hsp60 knockout and transgenic CHOP mouse models. ASSOCIATED FELLOWS GRK Progress Report 2011-2014 | Page 73 Aim The aim of the PhD-Thesis is to elucidate the impact of high-fat diets on the intestinal barrier integrity, inflammatory processes in the gut and peripheral adipose tissue. There- fore several mouse models were used which were genetically differently sensitive to high-fat diets. In addition we will char- acterize the role of the mitochondrial chaperone HSP60 and its transcriptional factor CHOP, UPR-related proteins, in main- taining homeostasis of different adipose tissue depots under experimental control and high-fat diets. For that reason adipose- specific (Adiponectin-Cre) hsp60 knockout and transgenic CHOP mouse models should be established. Methods and Results For the first experimental setup male C57Bl/6J, AKR/J and SWR/J mice were fed control (12 kJ% from fat; CD) or high-fat diet (48 kJ% from fat) for 4 weeks. Histopathological analysis of all intestinal sections was performed by H&E staining. Barrier function was measured in vivo by determining the PEG-trans- location in the urine via LC-MS technique and ex vivo by west- ern blot analysis, quantitative real-time-PCR, immunofluores- cence and immunohistochemistry. C57Bl/6J and AKR/J mice showed a significantly increase in body weight as well as an impaired glucose tolerance after a 4 weeks high-fat feeding period compared to the control-diet fed mice. In contrast SWR/J mice failed to gain body weight associated with normal blood glucose levels under HFD. Histo- pathology analysis revealed no signs of inflammation in all in- testinal sections. Macroscopic analysis like PEG-translocation and transepithelial resistance of the gut barrier revealed an in- tact gut barrier function after a high-fat feeding period. Western Blot and qPCR analysis as well as immunostainings of ileal and colonic tissue sections also showed no impaired gut barrier in all mice. The tight junction protein Occludin which connects the epithelial cells on the apical side and contributes to an intact cell layer and E-Cadherin, a cell-cell adhesion molecule, were not differently expressed under HFD. To further characterize the impact of HFD on UPR mitochondrial UPR-signaling and induction of inflammatory mechanisms such as macrophage and T-cell infiltration in gut and fat tissues will be analyzed in conditional hsp60 knockout and transgenic CHOP mice. Outlook The next experiments will focus on differently concentrated high-fat diets, meaning an increase of food density from 48 kJ% to 60 kJ% fat, and different fatty acid compositions, meaning a Figure: Immunofluorescence staining revealed that high-fat feeding does not affect the expression of the tight-junctional protein Occludin (green) and the adhesion protein E-cadherin (red) in distal ileum tissue of C57Bl/6J, SWR/J and AKR/J mice. Supervisors Prof. Dr. Dirk Haller | TUM | Nutrition and Immunology Start of project: March 2012 Academic background: Studies of Biology at Ludwig-Maximilians-Universität München