Differential Gene Expression in Intestinal Epithelial Cells Induced bij Single and Mixtures of Potato Glycoalkaloids

¿-Chaconine and ¿-solanine are naturally occurring toxins. They account for 95% of the total glycoalkaloids in potatoes (Solanum tuberosum L.). At high levels, these glycoalkaloids may be toxic to humans, mainly by disrupting cell membranes of the gastrointestinal tract. Gene-profiling experiments were performed, whereby Caco-2 cells were exposed to equivalent concentrations (10 µM) of pure ¿-chaconine or ¿-solanine or glycoalkaloid mixtures of varying ¿-chaconine/¿-solanine ratios for 6 h. In addition, lactate dehydrogenase, cell cycle, and apoptosis analyses experiments were also conducted to further elucidate the effects of glycoalkaloids. The main aims of the study were to determine the transcriptional effects of these glycoalkaloid treatments on Caco-2 cells and to investigate DNA microarray utility in conjunction with conventional toxicology in screening for potential toxicities and their severity. Gene expression and pathway analyses identified changes related to cholesterol biosynthesis, growth signaling, lipid and amino acid metabolism, mitogen-activated protein kinase (MAPK) and NF-¿B cascades, cell cycle, and cell death/apoptosis. To varying extents, DNA microarrays discriminated the severity of the effect among the different glycoalkaloid treatments

Lycopene bioaccessibility and starch digestibility for extruded snacks enriched with tomato derivatives

To improve the nutritional value of energy-dense extruded snacks, corn grits were replaced with tomato paste and/or tomato skin powder at ratios of 5, 10, and 20% and extruded to make expanded snack foodlike products. Using a model digestion system, lycopene bioaccessibility and uptake from the snacks into Caco-2 cells were determined. The digestibility of the starch, the main nutrient component of the snacks, was also investigated. While extrusion cooking reduced the lycopene content of the snacks, the proportion of bioaccessible lycopene increased. Lycopene uptake by the Caco-2 cells from the extruded snacks exceeded that of the control in which the lycopene was not extruded, by 5% (p < 0.05). The digestibility of starch in the snacks varied depending on the type of tomato derivative and its concentration. Optimization of the extrusion cooking process and the ingredients can yield functional extruded snack products that contain bioavailable lycopene. © 2011 American Chemical Society

Polyunsaturated fatty acids modify colorectal epithelial cell cytokine expression in a leucocyte co-culture model in response to probiotic bacteria

Diets high in n–3 polyunsaturated fatty acids (PUFAs) have been linked to improved colorectal health(1). One possible mechanism underlying this observation is that different PUFAs affect the immune response of epithelial cells to beneficial bacteria such as probiotics. The aim of this study was therefore to test whether pre-incubation of cells with different PUFAs would modify the epithelial cell response to probiotic bacteria

Polyunsaturated fatty acids modify expression of TGF-β in a co-culture model utilising human colorectal cells and human peripheral blood mononuclear cells exposed to Lactobacillus gasseri, Escherichia coli and Staphylococcus aureus

Commensal bacteria and polyunsaturated fatty acids (PUFAs) have both been shown independently to modulate immune responses. This study tested the hypothesis that the different colonic immunomodulatory responses to commensal (Lactobacillus gasseri) and pathogenic bacteria (Escherichia coli and Staphylococcus aureus) may be modified by PUFAs. Experiments used a Transwell system combining the colorectal cell line HT29, or its mucous secreting sub-clone HT29-MTX, with peripheral blood mononuclear cells to analyse immunomodulatory signalling in response to bacteria, with and without prior treatment with arachidonic acid, eicosapentaenoic acid or docosahexaenoic acid. L. gasseri increased transforming growth factor β1 (TGF-β1) mRNA and protein secretion in colonic cell lines when compared with controls, an effect that was enhanced by pre-treatment with eicosapentaenoic acid. In contrast, the Gram-negative pathogen E. coli LF82 had no significant effect on TGF-β1 protein. L. gasseri also increased IL-8 mRNA but not protein while E. coli increased both; although differences between PUFA treatments were detected, none were significantly different to controls. Colonic epithelial cells show different immunomodulatory signalling patterns in response to the commensal L. gasseri compared to E. coli and S. aureus and pre-treatment of these cells with PUFAs can modify responses. Practical applications: We have demonstrated an interaction between dietary PUFAs and epithelial cell response to both commensal and pathogenic bacteria found in the gastrointestinal tract by utilising in vitro co-culture models. The data suggest that n-3 PUFAs may provide some protection against the potentially damaging effects of pathogens. Furthermore, the beneficial effects of combining n-3 PUFAs and the commensal bacteria, and potential probiotic, L. gasseri are illustrated by the increased expression of immunoregulatory TGF-β1. © 2014 The Authors

PI3K/AKT, JNK, and ERK pathways are not crucial for the induction of cholesterol biosynthesis gene transcription in intestinal epithelial cells following treatment with the potato glycoalkaloid α-chaconine

We previously reported that exposure of the intestinal epithelial Caco-2 cell line to noncytotoxic concentrations of potato glycoalkaloids resulted in increased expression of cholesterol biosynthesis genes. Genes involved in mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/v-akt murine thymoma viral oncogene homologue (AKT) pathways and their downstream effectors such as Jun, c-Myc, and Fos also were induced. MAPK and PI3K/AKT pathways have been described to regulate the activity of sterol regulatory element binding transcription factors (SREBPs) and consequently the expression of cholesterol biosynthesis genes. In this study, to understand the mechanism of induction of cholesterol biosynthesis upon α-chaconine treatment, its effect on SREBP-2 protein levels was investigated. We also examined whether MAPK and PI3K/AKT pathways are required for the observed induction of these genes following exposure of cells to α-chaconine. Differentiated Caco-2 cells were pretreated with LY294002 (PI3K inhibitor), PD98059 (MEK1 inhibitor), or SP600125 (JNK inhibitor) or a combination of all inhibitors for 24 h prior to coincubation with 10, μM α-chaconine for 6 h. Significant increases in precursor and mature protein levels of SREBP-2 were observed after α-chaconine exposure. We also observed that α-chaconine treatment resulted in significant phosphorylation of AKT, extracellular signal related protein kinase (ERK), and c-jun N terminal protein kinase (JNK) but not that of p38. In general, the kinase inhibitor experiments revealed that phosphorylation of kinases of PI3K/AKT, ERK, and JNK pathways was not crucial for the induction of expression of cholesterol biosynthesis genes, with the exception of SC5DL. The transcription of this later gene was reduced when all three pathways were inhibited. On the basis of these results, it can be postulated that other mechanisms, which may be independent of the MAPK and PI3K/AKT pathways, including possibly post-translational activation of SREBP-2, may be more pivotal for the induction of cholesterol biosynthesis genes following exposure of intestinal cells to α-chaconine. © 2008 American Chemical Society

How fish oils could support our friendly bacteria

Commensal gut bacteria are generally considered to be friendly bacteria, since they can help their host in numerous ways. These can include breaking down undigested food to produce metabolites (by‐products), which can be a fuel source for gut cells and can help to regulate the immune system, amongst many other beneficial functions that support the host's health. Probiotic bacteria are bacteria that offer a benefit to their host. They are used in dietary supplements and many are of the genus Lactobacilli. We tested whether gut cells respond differently to a commensal bacterium (Lactobacillus gasseri) and two pathogenic bacteria (Escherichia coli and Staphylococcus aureus), and also whether the responses could be altered with PUFAs. We used a cell co‐culture model containing a layer of colorectal cells, with immune cells in a porous compartment beneath. This model represents the outer cell lining of our lower gut and the immune cells that sit underneath in an area called the lamina propria. We showed that commensal L. gasseri increased the secretion of the immune signalling protein TGF‐β1 (Transforming Growth Factor β1), along with increased expression of its encoding gene signal. TGF‐β1 has an important role in promoting tolerance towards commensal bacteria and has a role in dampening immune responses following inflammation. The pathogenic bacteria had no effect on the amount of TGF‐β1. Our results indicate that L. gasseri could have a way of promoting its own survival in the gut by inducing tolerance towards itself, an effect which pathogenic bacteria do not have. When eicosapentaenoic acid was added to the cell culture model along with L. gasseri, there was a greater increase in TGF‐β1 gene expression. This early research shows the potential of combining fish oil with probiotic bacteria to promote probiotic survival in the gut and/or dampening inflammatory responses

A 28-day repeat dose toxicity study of steroidal glycoalkaloids, α-solanine and α-chaconine in the Syrian Golden hamster

Glycoalkaloids α-solanine and α-chaconine are naturally present toxicants in the potato plant (Solanum tuberosum). Human intake of high doses of glycoalkaloids has led to acute intoxication, in severe cases coma and death. Previous studies have indicated that the ratio of α-solanine to α-chaconine may determine the degree and nature of the glycoalkaloid toxicity in potatoes, as the toxicity of the two alkaloids act synergistically. The aim of the present study was to investigate whether an altered ratio of α-solanine and α-chaconine would reduce the toxicity of the glycoalkaloids. The Syrian Golden hamster was given daily doses of α-solanine and α-chaconine by gavage for 28 days. Doses of up to 33.3 mg total glycoalkaloids/kg body weight were applied in ratios of 1:3.7 and 1:70 (α-solanine:α-chaconine). Administration of the highest doses of both ratios resulted in distended and fluid filled small intestines and stomach. Animals receiving the ratio with the reduced content of α-solanine were less affected compared to those receiving the other ratio. Gene expression profiling experiments were conducted using RNA from epithelial scrapings from the small intestines of the hamsters administered the highest doses of the glycoalkaloid treatments. In general, more differential gene expression was observed in the epithelial scrapings of the hamsters fed the ratio of 1:3.7. Mostly, pathways involved in lipid and energy metabolism were affected by the ratio of 1:3.7. © 2009 Elsevier Ltd. All rights reserved

Does dietary broccoli fibre influence body composition of the healthy rat in the presence of high and low fat?

Background: Daily intake of dietary fibre is important in preventing gut-related disorders, cardiovascular diseases, type 2 diabetes, cancer and obesity. Fermentable carbohydrates such as pectin, gums, resistant starch, and non-starch polysaccharides can enhance the metabolic absorption of minerals, including calcium, magnesium and iron from the gut. Objective: To determine if feeding broccoli fibre in high and low fat diets alters body composition and bone density in the healthy rat. Design: Sixty-four male Sprague Dawley rats (9 weeks of age) were fed four experimental dietary treatments (16 rats per treatment) for 17 weeks. The dietary treatments were: 1) low corn oil and cellulose, 2) low corn oil and broccoli fibre, 3) high corn oil and cellulose, and 4) high corn oil and broccoli fibre. Body composition and bone density were assessed by DEXA scan analysis. Serum levels of C-terminal telopeptides of type 1 collagen (CTX), a resorption marker, were also measured. Outcomes: Body fat mass (p=0.002) and fat percentage (p<0.001) were significantly higher in rats fed the high fat diets. Lean mass, lumbar spine (area, bone mineral content and density), and femur measurements (bone mineral content and density) were higher in rats fed the low fat diets. Broccoli fibre supplementation increased lumbar spine area (p=0.040), lumbar spine bone mineral content (p=0.077), femur area (p=0.079), and femur bone mineral content (p=0.074). Conclusion: Low fat diets increased lean mass and bone area, mineral content and density in the lumbar spine and femur. Broccoli fibre supplementation had only a small impact on bone health through increased lumbar spine bone area

Influence of dietary blueberry and broccoli on cecal microbiota activity and colon morphology in mdr1a−/− mice, a model of inflammatory bowel diseases

Objective: Enteric microbiota has been shown to be associated with various pathological conditions such as inflammatory bowel disease (IBD). This study aimed to determine the anti-inflammatory colonic effects of blueberries and broccoli in mdr1a -/- mice (IBD mouse model) through modification of microbiota composition in the gastrointestinal tract. Methods: The mdr1a -/- mice were fed either a control diet or the control diet supplemented with either 10% blueberry or broccoli for 21 wk. We investigated the influence of these diets on cecal microbiota and organic acids, colon morphology, and bacterial translocation to mesenteric lymph nodes. Results: In comparison to mice fed the control diet, blueberry and broccoli supplementation altered cecum microbiota similarly with the exception of Faecalibacterium prausnitzii, which was found to be significantly lower in broccoli-fed mice. High concentrations of butyric acid and low concentrations of succinic acid were observed in the cecum of broccoli-fed mice. Blueberry- and broccoli-supplemented diets increased colon crypt size and the number of goblet cells per crypt. Only the broccoli-supplemented diet significantly lowered colonic inflammation compared to mice fed the control diet. Translocation of total microbes to mesenteric lymph nodes was lower in broccoli-fed mice compared to blueberry and control diet groups. Conclusion: Dietary blueberries and/or broccoli altered the composition and metabolism of the cecal microbiota and colon morphology. Overall, these results warrant further investigation through clinical studies to establish whether the consumption of blueberries and/or broccoli is able to alter the composition and metabolism of large intestine microbiota and promote colon health in humans. © 2012 Elsevier Inc