The intestinal microbiota and its metabolites appear to be an important factor for gastrointestinal function and health. However, research is still needed to further elaborate potential relationships between nutrition, gut microbiota and host’s health by means of a suitable animal model. The present study examined the effect of two different diets on microbial composition and activity by using the pig as a model for humans. Eight pigs were equally allotted to two treatments, either fed a low-fat/high-fiber (LF), or a high-fat/low-fiber (HF) diet for 7 weeks. Feces were sampled at day 7 of every experimental week. Diet effects on fecal microbiota were assessed using quantitative real-time PCR, DNA fingerprinting and metaproteomics. Furthermore, fecal short-chain fatty acid (SCFA) profiles and ammonia concentrations were determined. Gene copy numbers of lactobacilli, bifidobacteria (P<0.001) and Faecalibacterium prausnitzii (P<0.05) were higher in the LF pigs, while Enterobacteriaceae were more abundant in the HF pigs (P<0.001). Higher numbers of proteins affiliated to Enterobacteriaceae were also present in the HF samples. Proteins for polysaccharide breakdown did almost exclusively originate from Prevotellaceae. Total and individual fecal SCFA concentrations were higher for pigs of the LF treatment (P0.05). Results provide evidence that beginning from the start of the experiment, the LF diet stimulated beneficial bacteria and SCFA production, especially butyrate (P<0.05), while the HF diet fostered those bacterial groups which have been associated with a negative impact on health conditions. These findings correspond to results in humans and might strengthen the hypothesis that the response of the porcine gut microbiota to a specific dietary modulation is in support of using the pig as suitable animal model for humans to assess diet-gut-microbiota interactions. Data are available via ProteomeXchange with identifier PXD003447.

Objective Increased fasting blood ethanol levels, suggested to stem from an increased endogenous ethanol synthesis in the GI tract, are discussed to be critical in the development of non-alcoholic fatty liver disease (NAFLD). The aim of the present study was to further delineate the mechanisms involved in the elevated blood ethanol levels found in patients with NAFLD. Design In 20 nutritionally and metabolically screened children displaying early signs of NAFLD and 29 controls (aged 5–8 years), ethanol plasma levels were assessed. Ethanol levels along the GI tract, in vena cava and portal vein, intestinal and faecal microbiota, and activity of alcohol dehydrogenase (ADH) and cytochrome P450 2E1 (CYP2E1) were measured in wild-type, ob/ob and anti-TNFα antibody (aT) treated ob/ob mice. Results Despite not differing in dietary pattern or prevalence of intestinal overgrowth, fasting ethanol levels being positively associated with measures of insulin resistance were significantly higher in children with NAFLD than in controls. Ethanol levels were similar in portal vein and chyme obtained from different parts of the GI tract between groups while ethanol levels in vena cava plasma were significantly higher in ob/ob mice. ADH activity was significantly lower in liver tissue obtained from ob/ob mice in comparison to wild-type controls and ob/ob mice treated with aT. Conclusions Taken together, our data of animal experiments suggest that increased blood ethanol levels in patients with NAFLD may result from insulin-dependent impairments of ADH activity in liver tissue rather than from an increased endogenous ethanol synthesis. Trial registration number NCT01306396.

Essential oils (EOs) have attracted increased interest for different applications such as food preservatives, feed additives and ingredients in cosmetics. Due to their reported variable composition of components, they might be acutely toxic to humans and animals in small amounts. Despite the necessity, rigorous toxicity testing in terms of safety evaluation has not been reported so far, especially using alternatives to animal models. Here, we provide a strategy by use of alternative in vitro (cell cultures) and in vivo (Caenorhabditis elegans, hen’s egg test) approaches for detailed investigation of the impact of commonly used rosemary, citrus and eucalyptus essential oil on acute, developmental and reproductive toxicity as well as on mucous membrane irritation. In general, all EOs under study exhibited a comparable impact on measured parameters, with a slightly increased toxic potential of rosemary oil. In vitro cell culture results indicated a concentration-dependent decrease of cell viability for all EOs, with mean IC₅₀ values ranging from 0.08 to 0.17% [v/v]. Similar results were obtained for the C. elegans model when using a sensitized bus-5 mutant strain, with a mean LC₅₀ value of 0.42% [v/v]. In wild-type nematodes, approximately tenfold higher LC₅₀ values were detected. C. elegans development and reproduction was already significantly inhibited at concentrations of 0.5% (wild-type) and 0.1% (bus-5) [v/v] of EO, respectively. Gene expression analysis revealed a significant upregulation of xenobiotic and oxidative stress genes such as cyp-14a3, gst-4, gpx-6 and sod-3. Furthermore, all three EOs under study showed an increased short-time mucous membrane irritation potential, already at 0.5% [v/v] of EO. Finally, GC–MS analysis was performed to quantitate the relative concentration of the most prominent EO compounds. In conclusion, our results demonstrate that EOs can exhibit severe toxic properties, already at low concentrations. Therefore, a detailed toxicological assessment is highly recommended for each EO and single intended application.

To further elaborate interactions between nutrition, gut microbiota and host health, an animal model to simulate changes in microbial composition and activity due to dietary changes similar to those in humans is needed. Therefore, the impact of two different diets on cecal and colonic microbial gene copies and metabolic activity, organ development and biochemical parameters in blood serum was investigated using a pig model. Four pigs were either fed a low-fat/high-fiber (LF), or a high-fat/low-fiber (HF) diet for seven weeks, with both diets being isocaloric. A hypotrophic effect of the HF diet on digestive organs could be observed compared to the LF diet (p < 0.05). Higher gene copy numbers of Bacteroides (p < 0.05) and Enterobacteriaceae (p < 0.001) were present in intestinal contents of HF pigs, bifidobacteria were more abundant in LF pigs (p < 0.05). Concentrations of acetate and butyrate were higher in LF pigs (p < 0.05). Glucose was higher in HF pigs, while glutamic pyruvic transaminase (GPT) showed higher concentrations upon feeding the LF diet (p < 0.001). However, C-reactive protein (CRP) decreased with time in LF pigs (p < 0.05). In part, these findings correspond to those in humans, and are in support of the concept of using the pig as human model.

Climatic changes and heat stress have become a great challenge in the livestock industry, negatively affecting, in particular, poultry feed intake and intestinal barrier malfunction. Recently, phytogenic feed additives were applied to reduce heat stress effects on animal farming. Here, we investigated the effects of ginseng extract using various in vitro and in vivo experiments. Quantitative real-time PCR, transepithelial electrical resistance measurements and survival assays under heat stress conditions were carried out in various model systems, including Caco-2 cells, Caenorhabditis elegans and jejunum samples of broilers. Under heat stress conditions, ginseng treatment lowered the expression of HSPA1A (Caco-2) and the heat shock protein genes hsp-1 and hsp-16.2 (both in C. elegans), while all three of the tested genes encoding tight junction proteins, CLDN3, OCLN and CLDN1 (Caco-2), were upregulated. In addition, we observed prolonged survival under heat stress in Caenorhabditis elegans, and a better performance of growing ginseng-fed broilers by the increased gene expression of selected heat shock and tight junction proteins. The presence of ginseng extract resulted in a reduced decrease in transepithelial resistance under heat shock conditions. Finally, LC-MS analysis was performed to quantitate the most prominent ginsenosides in the extract used for this study, being Re, Rg1, Rc, Rb2 and Rd. In conclusion, ginseng extract was found to be a suitable feed additive in animal nutrition to reduce the negative physiological effects caused by heat stress.