Impaired barrier function by dietary fructo-oligosaccharides (FOS) in rats is accompanied by increased colonic mitochondrial gene expression

<p>Abstract</p> <p>Background</p> <p>Dietary non-digestible carbohydrates stimulate the gut microflora and are therefore presumed to improve host resistance to intestinal infections. However, several strictly controlled rat infection studies showed that non-digestible fructo-oligosaccharides (FOS) increase, rather than decrease, translocation of <it>Salmonella </it>towards extra-intestinal sites. In addition, it was shown that FOS increases intestinal permeability already before infection. The mechanism responsible for this adverse effect of FOS is unclear. Possible explanations are altered mucosal integrity due to changes in tight junctions or changes in expression of defense molecules such as antimicrobials and mucins. To examine the mechanisms underlying weakening of the intestinal barrier by FOS, a controlled dietary intervention study was performed. Two groups of 12 rats were adapted to a diet with or without FOS. mRNA was collected from colonic mucosa and changes in gene expression were assessed for each individual rat using Agilent rat whole genome microarrays.</p> <p>Results</p> <p>Among the 997 FOS induced genes we observed less mucosal integrity related genes than expected with the clear permeability changes. FOS did not induce changes in tight junction genes and only 8 genes related to mucosal defense were induced by FOS. These small effects are unlikely the cause for the clear increase in intestinal permeability that is observed. FOS significantly increased expression of 177 mitochondria-related genes. More specifically, induced expression of genes involved in all five OXPHOS complexes and the TCA cycle was observed. These results indicate that dietary FOS influences intestinal mucosal energy metabolism. Furthermore, increased expression of 113 genes related to protein turnover, including proteasome genes, ribosomal genes and protein maturation related genes, was seen. FOS upregulated expression of the peptide hormone proglucagon gene, in agreement with previous studies, as well as three other peptide hormone genes; peptide YY, pancreatic polypeptide and cholecystokinin.</p> <p>Conclusion</p> <p>We conclude that altered energy metabolism may underly colonic barrier function disruption due to FOS feeding in rats.</p

Beta-Carotene Reduces Body Adiposity of Mice via BCMO1

Evidence from cell culture studies indicates that β-carotene-(BC)-derived apocarotenoid signaling molecules can modulate the activities of nuclear receptors that regulate many aspects of adipocyte physiology. Two BC metabolizing enzymes, the BC-15,15′-oxygenase (Bcmo1) and the BC-9′,10′-oxygenase (Bcdo2) are expressed in adipocytes. Bcmo1 catalyzes the conversion of BC into retinaldehyde and Bcdo2 into β-10′-apocarotenal and β-ionone. Here we analyzed the impact of BC on body adiposity of mice. To genetically dissect the roles of Bcmo1 and Bcdo2 in this process, we used wild-type and Bcmo1-/- mice for this study. In wild-type mice, BC was converted into retinoids. In contrast, Bcmo1-/- mice showed increased expression of Bcdo2 in adipocytes and β-10′-apocarotenol accumulated as the major BC derivative. In wild-type mice, BC significantly reduced body adiposity (by 28%), leptinemia and adipocyte size. Genome wide microarray analysis of inguinal white adipose tissue revealed a generalized decrease of mRNA expression of peroxisome proliferator-activated receptor γ (PPARγ) target genes. Consistently, the expression of this key transcription factor for lipogenesis was significantly reduced both on the mRNA and protein levels. Despite β-10′-apocarotenoid production, this effect of BC was absent in Bcmo1-/- mice, demonstrating that it was dependent on the Bcmo1-mediated production of retinoids. Our study evidences an important role of BC for the control of body adiposity in mice and identifies Bcmo1 as critical molecular player for the regulation of PPARγ activity in adipocyte

Knockout of the Bcmo1 gene results in an inflammatory response in female lung, which is suppressed by dietary beta-carotene

Beta-carotene 15,15′-monooxygenase 1 knockout (Bcmo1−/−) mice accumulate beta-carotene (BC) similarly to humans, whereas wild-type (Bcmo1+/+) mice efficiently cleave BC. Bcmo1−/− mice are therefore suitable to investigate BC-induced alterations in gene expression in lung, assessed by microarray analysis. Bcmo1−/− mice receiving control diet had increased expression of inflammatory genes as compared to BC-supplemented Bcmo1−/− mice and Bcmo1+/+ mice that received either control or BC-supplemented diets. Differential gene expression in Bcmo1−/− mice was confirmed by real-time quantitative PCR. Histochemical analysis indeed showed an increase in inflammatory cells in lungs of control Bcmo1−/− mice. Supported by metabolite and gene-expression data, we hypothesize that the increased inflammatory response is due to an altered BC metabolism, resulting in an increased vitamin A requirement in Bcmo1−/− mice. This suggests that effects of BC may depend on inter-individual variations in BC-metabolizing enzymes, such as the frequently occurring human polymorphisms in BCMO1

Identification of cat sequences required for intron-dependent gene expression in maize cells

Transgene expression in maize cells changed from intron-independent to intron-dependent by an exact exchange of the bar coding region for that of cat. By deletion mapping an approximately 100 nucleotide sequence element at the 5' end of the cat coding region was identified that, when inserted at the translation start site of the bar gene, impaired expression. Successive inclusion of the salT intron in the 5' untranslated region (UTR) restored expression near to wild-type bar expression levels. A chimeric gfp gene, but not nptII gene, behaved similarly. These observations are in agreement with the view that intron-mediated enhancement of transgene expression does not enhance, but rather restores expression of an impaired gene

Transcription profiling of rat colonic mucosa at different time points following Salmonella infection

Salmonella enteritidis is suggested to translocate in the small intestine. Previously we identified that prebiotics, fermented in the colon, increased Salmonella translocation in rats, suggesting involvement of the colon in translocation. Effects of Salmonella on colonic gene expression in vivo are largely unknown. The aim of this study was to characterize time dependent Salmonella induced changes of colonic mucosal gene expression in rats using whole genome microarrays. Rats were orally infected with Salmonella enteritidis to mimic a foodbore infection and colonic gene expression was determined at day 1, 3 and 6 post-infection (n=8 per timepoint). Agilent rat whole genome microarray (G4131A Agilent Technologies) were used. Results indicate that colon is clearly a target tissue for Salmonella considering the abundant changes in mucosal gene expression observed

Transcription profiling of rat colonic mucosa at different time points following Salmonella infection

Salmonella enteritidis is suggested to translocate in the small intestine. Previously we identified that prebiotics, fermented in the colon, increased Salmonella translocation in rats, suggesting involvement of the colon in translocation. Effects of Salmonella on colonic gene expression in vivo are largely unknown. The aim of this study was to characterize time dependent Salmonella induced changes of colonic mucosal gene expression in rats using whole genome microarrays. Rats were orally infected with Salmonella enteritidis to mimic a foodbore infection and colonic gene expression was determined at day 1, 3 and 6 post-infection (n=8 per timepoint). Agilent rat whole genome microarray (G4131A Agilent Technologies) were used. Results indicate that colon is clearly a target tissue for Salmonella considering the abundant changes in mucosal gene expression observed

Gene expression changes in cecum mucosa upon dietary treatment

To increase our knowledge of the effects of Fructo oligosaccharides (FOS) on the intestinal barrier function in rats, a controlled rat infection study was performed. Two groups of rats (n=12 per group) were adapted to a diet with or without FOS. mRNA was collected from the mucosa of the cecum and changes in gene expression were assessed using an agilent rat whole genome microarray (G4131A Agilent Technologies). Results indicate that dietary FOS influences immune response and wound healing mechanisms, which will most likely affect the intestinal barrier

Colonic gene expression upon dietary treatment

To increase our knowledge of the effects of Fructo oligosaccharides (FOS) on the intestinal barrier function in rats, a controlled rat infection study was performed. Two groups of rats were adapted to a diet with or without FOS. mRNA was collected from the mucosa of the colon and changes in gene expression were assessed using an agilent rat whole genome microarray (G4131A Agilent Technologies). Results indicate that dietary FOS influences energy metabolism, which will most likely play a role in the effects of FOS on the intestinal barrier

Colonic gene expression upon dietary treatment

To increase our knowledge of the effects of Fructo oligosaccharides (FOS) on the intestinal barrier function in rats, a controlled rat infection study was performed. Two groups of rats were adapted to a diet with or without FOS. mRNA was collected from the mucosa of the colon and changes in gene expression were assessed using an agilent rat whole genome microarray (G4131A Agilent Technologies). Results indicate that dietary FOS influences energy metabolism, which will most likely play a role in the effects of FOS on the intestinal barrier

Colonic gene expression upon Salmonella infection and dietary treatment

To increase our knowledge of the effects of Fructo oligosaccharides (FOS) on Salmonella infection in fats, a controlle rat infection study was performed. Two groups of 12 rats were adapted for 14 days to a cellulose diet and one group of 12 rats to a FOS diet. One cellulose-fed group and the FOS-fed group were infected with Salmonella. Two days post infection mRNA was collected from the mucosa of the colon and changes in gene expression were assessed using an Agilent rat whole genome microarray (G4131A Agilent Technologies). Results indicate that Salmonella affects colonic mucosal gene expression, which is further enhanded by dietary FOS