Background: The selective absorption of nutrients and other food constituents in the small intestine is mediated by a group of transport proteins and metabolic enzymes, often collectively called intestinal barrier proteins. An important receptor that mediates the effects of dietary lipids on gene expression is the peroxisome proliferator-activated receptor alpha (PPAR), which is abundantly expressed in enterocytes. In this study we examined the effects of acute nutritional activation of PPAR on expression of genes encoding intestinal barrier proteins. To this end we used triacylglycerols composed of identical fatty acids in combination with gene expression profiling in wild-type and PPAR-null mice. Treatment with the synthetic PPAR agonist WY14643 served as reference.
PPARalpha-mediated effects of dietary lipids on intestinal barrier gene expression.
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View SamplesWe studied the effect of dietary fat type, varying in polyunsaturated/saturated fatty acid ratio's (P/S) on development of metabolic syndrome. C57Bl/6J mice were fed purified high-fat diets (45E% fat) containing palm oil (HF-PO; P/S 0.4), olive oil (HF-OO; P/S 1.1) or safflower oil (HF-SO; P/S 7.8) for 8 weeks. A low-fat palm oil diet (LF-PO; 10E% fat) was used as a reference. Additionally, we analyzed diet-induced changes in gut microbiota composition and mucosal gene expression. The HF-PO diet induced a higher body weight gain and liver triglyceride content compared to the HF-OO, HF-SO or LF-PO diet. In the intestine, the HF-PO diet reduced microbial diversity and increased the Firmicutes/Bacteroidetes ratio. Although this fits a typical obesity profile, our data clearly indicate that an overflow of the HF-PO diet to the distal intestine, rather than obesity itself, is the main trigger for these gut microbiota changes. A HF-PO diet-induced elevation of lipid metabolism-related genes in the distal small intestine confirmed the overflow of palm oil to the distal intestine. Some of these lipid metabolism-related genes were previously already associated with the metabolic syndrome. In conclusion, our data indicate that saturated fat (HF-PO) has a more stimulatory effect on weight gain and hepatic lipid accumulation than unsaturated fat (HF-OO and HF-SO). The overflow of fat to the distal intestine on the HF-PO diet induced changes in gut microbiota composition and mucosal gene expression. We speculate that both are directly or indirectly contributive to the saturated fat-induced development of obesity and hepatic steatosis.
Saturated fat stimulates obesity and hepatic steatosis and affects gut microbiota composition by an enhanced overflow of dietary fat to the distal intestine.
Sex, Specimen part
View SamplesFindings suggest that PPARalpha plays a decisive role in the development of hypertrophy, affecting the functional outcome of the heart. Unfortunately, information on the nature of PPARalpha-dependent processes in cardiac hypertrophy is fragmentary and incomplete.
Transcriptomic analysis of PPARalpha-dependent alterations during cardiac hypertrophy.
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View SamplesIntegrins facilitate intercellular movement and communication. Unlike the promiscuous activities of many integrins, 6 integrin is restricted to epithelia and partners exclusively with integrin V to modulate acute lung injury (ALI). Given that ALI is a complication of respiratory infection, we used mice lacking 6 integrin (6 KO) to probe the role of the epithelial layer in controlling the lung microenvironment during infection. We found 6 KO mice were protected from disease caused by influenza and Sendai virus infections. They were also protected from disease caused by Streptococcus pneumoniae infection alone and after prior influenza virus infection, the co-infection representing an often-lethal condition in humans. Resistance in the absence of epithelial 6 integrin was caused by intrinsic priming of the lung microenvironment by type I interferons through a mechanism involving transforming growth factor- regulation. Expression of 6 on epithelia suppresses the production of interferons, providing an advantage to the pathogen. Acute inhibition of 6 function may therefore provide a means to improve outcomes in lung microbial infections.
An Epithelial Integrin Regulates the Amplitude of Protective Lung Interferon Responses against Multiple Respiratory Pathogens.
Specimen part
View SamplesThe peroxisome proliferator-activated receptor alpha (PPAR) is a fatty acid-activated transcription factor that governs a variety of biological processes. Little is known about the role of PPAR in the small intestine. Since this organ is frequently exposed to high levels of PPAR ligands via the diet, we set out to characterize the function of PPAR in small intestine using functional genomics experiments and bioinformatics tools. PPAR was expressed at high levels in both human and murine small intestine. Detailed analyses showed that PPAR was expressed highest in villus cells of proximal jejunum. Microarray analyses of total tissue samples revealed, that in addition to genes involved in fatty acid and triacylglycerol metabolism, transcription factors and enzymes connected to sterol and bile acid metabolism, including FXR and SREBP1, were specifically induced. In contrast, genes involved in cell cycle and differentiation, apoptosis, and host defense were repressed by PPAR activation. Additional analyses showed that intestinal PPAR dependent gene regulation occurred in villus cells. Functional implications of array results were corroborated by morphometric data. The repression of genes involved in proliferation and apoptosis was accompanied by a 22% increase in villus height, and a 34% increase in villus area of wild-type animals treated with WY14643. This is the first report providing a comprehensive overview of processes under control of PPAR in the small intestine. We show that PPAR is an important transcriptional regulator in small intestine, which may be of importance for the development of novel foods and therapies for obesity and inflammatory bowel diseases.
Genome-wide analysis of PPARalpha activation in murine small intestine.
Sex, Age, Specimen part
View SamplesGene expression regulation of transporters and phase I/II metabolic enzymes in murine small intestine during fasting
Gene expression of transporters and phase I/II metabolic enzymes in murine small intestine during fasting.
Sex, Age, Specimen part
View SamplesThe polarization of macrophages into an anti-inflammatory or regulatory phenotype plays an important role in resolving inflammation. PGE2 regulates macrophage polarization via a PKA dependent pathway. PKA phosphorylates SIKs, inhibiting their ability to phosphorylate CRTC3 in cells. This in turn allows CRTC3 to translocate to the nucleus where it acts as a co-activator with the transcription factor CREB to induce IL-10 transcription. In line with this we find that either genetic or pharmacological inhibition of SIKs mimics the effect of PGE2 on IL-10 production.
PGE(2) induces macrophage IL-10 production and a regulatory-like phenotype via a protein kinase A-SIK-CRTC3 pathway.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Conversion of human fibroblasts to angioblast-like progenitor cells.
Sex, Specimen part, Cell line
View SamplesWe report a novel technique to reprogram human fibroblasts into endothelial and smooth muscle cells using partial iPSC reprogramming and chemically defined media. Using appropriate media conditions for differentiation of human pluripotent cells to CD34+ vascular progenitor cells, we show that temporary expression of pluripotent transcription factors and treatment with chemically-defined media, will induce differentiation of human fibroblasts to CD34+ vascular progenitor cells. Sorted CD34+ cells can then be directed to differentiate into vascular endothelial cells expressing a variety of smooth muscle markers.
Conversion of human fibroblasts to angioblast-like progenitor cells.
Sex, Specimen part
View SamplesThe objective of this study was to compare recall responses to vaccine antigens at 3 months and 9 months of age in infants who were vaccinated at birth or at 1 month.
Pneumococcal conjugate vaccination at birth in a high-risk setting: no evidence for neonatal T-cell tolerance.
Age, Specimen part, Treatment
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