Physiological concentrations of bile salts inhibit recovery of ischemic-injured porcine ileum

Encapsulation of a Desmodium intortum Protein Isolate Pickering Emulsion of β-Carotene: Stability, Bioaccesibility and Cytotoxicity

Owing to their excellent characteristics, Pickering emulsions have been widely used in the development and the application of new carriers for embedding and for delivering active compounds. In this study, β-carotene was successfully encapsulated in a Pickering emulsion stabilized using Desmodium intortum protein isolate (DIPI). The results showed that the encapsulation efficiencies of β-carotene in the control group Tween 20 emulsion (TE) and the DIPI Pickering emulsion (DIPIPE) were 46.7 ± 2.5% and 97.3 ± 0.8%, respectively. After storage for 30 days at 25 °C and 37 °C in a dark environment, approximately 79.4% and 72.1% of β-carotene in DIPIPE were retained. Compared with TE, DIPIPE can improve the stability of β-carotene during storage. In vitro digestion experiments showed that the bioaccessibility rate of β-carotene in DIPIPE was less than that in TE. Cytotoxicity experiments showed that DIPI and β-carotene micelles within a specific concentration range exerted no toxic effects on 3T3 cells. These results indicate that DIPIPE can be used as a good food-grade carrier for embedding and transporting active substances to broaden the application of the protein-based Pickering emulsion system in the development of functional foods.

Organic Solute Transporter α-β Protects Ileal Enterocytes From Bile Acid-Induced Injury

BACKGROUND & AIMS

Ileal bile acid absorption is mediated by uptake via the apical sodium-dependent bile acid transporter (ASBT), and export via the basolateral heteromeric organic solute transporter α-β (OSTα-OSTβ). In this study, we investigated the cytotoxic effects of enterocyte bile acid stasis in Ostα-/- mice, including the temporal relationship between intestinal injury and initiation of the enterohepatic circulation of bile acids.

METHODS

Ileal tissue morphometry, histology, markers of cell proliferation, gene, and protein expression were analyzed in male and female wild-type and Ostα-/- mice at postnatal days 5, 10, 15, 20, and 30. Ostα-/-Asbt-/- mice were generated and analyzed. Bile acid activation of intestinal Nrf2-activated pathways was investigated in Drosophila.

RESULTS

As early as day 5, Ostα-/- mice showed significantly increased ileal weight per length, decreased villus height, and increased epithelial cell proliferation. This correlated with premature expression of the Asbt and induction of bile acid-activated farnesoid X receptor target genes in neonatal Ostα-/- mice. Expression of reduced nicotinamide adenine dinucleotide phosphate oxidase-1 and Nrf2-anti-oxidant responsive genes were increased significantly in neonatal Ostα-/- mice at these postnatal time points. Bile acids also activated Nrf2 in Drosophila enterocytes and enterocyte-specific knockdown of Nrf2 increased sensitivity of flies to bile acid-induced toxicity. Inactivation of the Asbt prevented the changes in ileal morphology and induction of anti-oxidant response genes in Ostα-/- mice.

CONCLUSIONS

Early in postnatal development, loss of Ostα leads to bile acid accumulation, oxidative stress, and a restitution response in ileum. In addition to its essential role in maintaining bile acid homeostasis, Ostα-Ostβ functions to protect the ileal epithelium against bile acid-induced injury. NCBI Gene Expression Omnibus: GSE99579.

Effect of digestion and storage of human milk on free fatty acid concentration and cytotoxicity

OBJECTIVES

Fat is digested in the intestine into free fatty acids (FFAs), which are detergents and therefore toxic to cells at micromolar concentration. The mucosal barrier protects cells in the adult intestine, but this barrier may not be fully developed in premature infants. Lipase-digested infant formula, but not fresh human milk, has elevated FFAs and is cytotoxic to intestinal cells, and therefore could contribute to intestinal injury in necrotizing enterocolitis (NEC), but even infants exclusively fed breast milk may develop NEC. Our objective was to determine whether stored milk and milk from donor milk (DM) banks could also become cytotoxic, especially after digestion.

METHODS

We exposed cultured rat intestinal epithelial cells or human neutrophils to DM and milk collected fresh and stored at 4°C or -20°C for up to 12 weeks and then treated for 2 hours (37°C) with 0.1 or 1 mg/mL pancreatic lipase and/or trypsin and chymotrypsin.

RESULTS

DM and milk stored 3 days (at 4°C or -20°C) and then digested were cytotoxic. Storage at -20°C for 8 and 12 weeks resulted in an additional increase in cytotoxicity. Protease digestion decreased, but did not eliminate cell death.

CONCLUSIONS

Present storage practices may allow milk to become cytotoxic and contribute to intestinal damage in NEC.

Development of a multiple-bile-ion-sensing membrane electrode

A multiple-bile-ion-sensing polyvinyl chloride-based membrane electrode capable of monitoring any of the three common bile ions in humans, namely, cholate, deoxycholate, and chenodeoxycholate, was developed and characterized. Compared to single-bile-ion-sensing electrodes, it showed a sub-Nernstian response. All other electrode properties were, however, similar, making this a successful replacement for three individual electrodes. With appropriate conditioning, this electrode could repeatedly change selectivity without losing membrane activity. It was reproducible, was stable for 5 months, had low response time, and could be used to measure critical micelle concentrations. The lower limit of detection was 10 nM. Selectivity coefficients for various anions with respect to bile ions more or less followed the Hoffmeister series. Plots of R ((Nernst equivalent of slope in the presence of primary ion and a fixed amount of interfering ion)/(slope in the presence of only the primary ion)) vs square root of ionic strength for an interfering ion were linear. One major application of this electrode is its use in kinetics. We have tested its ability to monitor continuously changing bile ion concentrations during their interactions with a biocompatible polymer, polyethylene glycol (6000), and determined rate constants.

High-fat-induced intestinal permeability dysfunction associated with altered fecal bile acids

AIM: To investigate whether high-fat-feeding is associated with increased intestinal permeability via alterations in bile acid metabolism.

METHODS: Male C57Bl/6J mice were fed on a high-fat (n = 26) or low-fat diet (n = 24) for 15 wk. Intestinal permeability was measured from duodenum, jejunum, ileum and colon in an Ussing chamber system using 4 kDa FITC-labeled dextran as an indicator. Fecal bile acids were analyzed with gas chromatography. Segments of jejunum and colon were analyzed for the expression of farnesoid X receptor (FXR) and tumor necrosis factor (TNF).

RESULTS: Intestinal permeability was significantly increased by high-fat feeding in jejunum (median 0.334 for control vs 0.393 for high-fat, P = 0.03) and colon (0.335 for control vs 0.433 for high-fat, P = 0.01), but not in duodenum or ileum. The concentration of nearly all identified bile acids was significantly increased by high-fat feeding (P < 0.001). The proportion of ursodeoxycholic acid (UDCA) in all bile acids was decreased (1.4% ± 0.1% in high-fat vs 2.8% ± 0.3% in controls, P < 0.01) and correlated inversely with intestinal permeability (r = -0.72, P = 0.01). High-fat feeding also increased jejunal FXR expression, as well as TNF expression along the intestine, especially in the colon.

CONCLUSION: High-fat-feeding increased intestinal permeability, perhaps by a mechanism related to bile acid metabolism, namely a decreased proportion of fecal UDCA and increased FXR expression.

Detection of differentially regulated genes in ischaemic equine intestinal mucosa

REASONS FOR PERFORMING STUDY

Colic is a serious disease syndrome in horses. Much of the mortality is associated with ischaemic-injured intestine during strangulating obstruction, yet there is limited understanding of the associated molecular events. Identification of differentially expressed genes during ischaemic injury should expand our understanding of colic and may lead to novel targeted therapeutic approaches in the future.

OBJECTIVE

To isolate and identify differentially expressed genes in equine jejunum following a 2 h ischaemic event compared to normally perfused jejunum.

METHODS

Suppressive subtractive hybridisation was used to clone genes that are differentially expressed in equine jejunum injured by 2 h of complete ischaemia as compared to time-matched control jejunal tissues. Expression of selected clones was further evaluated by northern blot analysis.

RESULTS

Of the 384 clones selected, 157 were confirmed to possess cDNAs corresponding differentially expressed genes by dot blot analysis. Two genes, fatty acid binding protein 2 and calcium-activated chloride channel 4 were further confirmed to be differentially expressed by northern blot analysis.

CONCLUSIONS

Suppressive subtractive hybridisation can be used to detect changes in expression of a broad array of genes, as confirmed by northern blot analysis of selected genes.

POTENTIAL RELEVANCE

These initial results have identified a pool of equine intestinal epithelial genes that are differentially expressed following a 2 h ischaemic event. In particular, genes indicative of deranged metabolic activity and those potentially involved in early repair events were identified and may ultimately provide clues as to the nature of epithelial ischaemic injury in horses.

Characterization of the innate immune response to chronic aspiration in a novel rodent model

Background

Although chronic aspiration has been associated with several pulmonary diseases, the inflammatory response has not been characterized. A novel rodent model of chronic aspiration was therefore developed in order to investigate the resulting innate immune response in the lung.

Methods

Gastric fluid or normal saline was instilled into the left lung of rats (n = 48) weekly for 4, 8, 12, or 16 weeks (n = 6 each group). Thereafter, bronchoalveolar lavage specimens were collected and cellular phenotypes and cytokine concentrations of IL-1alpha, IL-1beta, IL-2, IL-4, IL-6, IL-10, GM-CSF, IFN-gamma, TNF-alpha, and TGF-beta were determined.

Results

Following the administration of gastric fluid but not normal saline, histologic specimens exhibited prominent evidence of giant cells, fibrosis, lymphocytic bronchiolitis, and obliterative bronchiolitis. Bronchoalveolar lavage specimens from the left (treated) lungs exhibited consistently higher macrophages and T cells with an increased CD4:CD8 T cell ratio after treatment with gastric fluid compared to normal saline. The concentrations of IL-1alpha, IL-1beta, IL-2, TNF-alpha and TGF-beta were increased in bronchoalveolar lavage specimens following gastric fluid aspiration compared to normal saline.

Conclusion

This represents the first description of the pulmonary inflammatory response that results from chronic aspiration. Repetitive aspiration events can initiate an inflammatory response consisting of macrophages and T cells that is associated with increased TGF-beta, TNF-alpha, IL-1alpha, IL-1beta, IL-2 and fibrosis in the lung. Combined with the observation of gastric fluid-induced lymphocyitic bronchiolitis and obliterative bronchiolitis, these findings further support an association between chronic aspiration and pulmonary diseases, such as obliterative bronchiolitis, pulmonary fibrosis, and asthma.

Dihydroxy bile acids increase mucosal permeability and bacterial uptake in human colon biopsies

OBJECTIVE

Bile acids in mM concentrations are known to increase chloride secretion and alter mucosal permeability in animal colon. Increased mucosal permeability is believed to play an important role in the development of intestinal inflammation. The aim of this study was to investigate the influence of microM concentrations of dihydroxy bile acids on permeability and bacterial uptake in the normal human colon.

MATERIAL AND METHODS

Endoscopic biopsies from the sigmoid colon of 18 subjects with normal colonic histology were mounted in modified Ussing chambers. Chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA) were added to the mucosal compartment. Short-circuit current (Isc) and transepithelial resistance (TER) were studied for 120 min. Cr-EDTA and horseradish peroxidase (HRP) were used to assess paracellular and transcellular permeability, respectively. The transmucosal passage of chemically killed Escherichia coli was quantified and investigated using confocal microscopy.

RESULTS

A significant decrease in TER was seen after 60 min of exposure to 1000 micromol/l CDCA and DCA. The combination of E. coli and 100 micromol/l CDCA gave a decrease in TER compared to controls (p = 0.06). DCA showed a dose-related increase in Cr-EDTA permeability, which was most pronounced at 1000 micromol/l (p = 0.02). Increased E. coli uptake was induced by 500 micromol/l (p = 0.01) and 1000 micromol/l CDCA (p = 0.04). Bacterial uptake was increased at 100 micromol/l by exposure to DCA (p = 0.03). Confocal microscopy revealed the presence of E. coli bacteria in the lamina propria after 15 min of exposure to 1000 micromol/l CDCA and DCA.

CONCLUSIONS

Our study suggests that dihydroxy bile acids in microM concentrations alter barrier function in normal human colon biopsies, causing increased antigen and bacterial uptake; thereby bile acids may contribute to the development of intestinal inflammation.