Extract Attenuates Inflammation and Oxidative Stress in Intestinal Epithelial Cells via NF-κB Activation and Nrf2 Response.

, dried root extract, also known as , is used in traditional Chinese medicine as a tonic remedy. Moreover, it has been reported that could attenuate intestinal inflammation; however, the underlying mechanism for its anti-inflammatory activity in intestinal epithelial cells (IECs) remains unclear. In this study, we evaluated extract (5-100 µg/mL) in a model of inflammation and oxidative stress for IECs.

The Food Contaminants Nivalenol and Deoxynivalenol Induce Inflammation in Intestinal Epithelial Cells by Regulating Reactive Oxygen Species Release.

mycotoxins are fungal metabolites whose ability to affect cereal grains as multi-contaminants is progressively increasing. The trichothecene mycotoxins nivalenol (NIV) and deoxynivalenol (DON) are often found in almost all agricultural commodities worldwide. They are able to affect animal and human health, including at the intestinal level.

Quantification of human diamine oxidase.

Objectives: Diamine oxidase (DAO) is essential for extracellular degradation of histamine. For decades activity assays with inherent limitations were used to quantify the relative amounts of DAO. No reference DAO standard is available.

Nivalenol induces oxidative stress and increases deoxynivalenol pro-oxidant effect in intestinal epithelial cells.

Mycotoxins are secondary fungal metabolites often found as contaminants in almost all agricultural commodities worldwide, and the consumption of food or feed contaminated by mycotoxins represents a major risk for human and animal health. Reactive oxygen species are normal products of cellular metabolism. However, disproportionate generation of reactive oxygen species poses a serious problem to bodily homeostasis and causes oxidative tissue damage.

Nivalenol and deoxynivalenol affect rat intestinal epithelial cells: a concentration related study.

The integrity of the gastrointestinal tract represents a crucial first level defence against ingested toxins. Among them, Nivalenol is a trichotecenes mycotoxin frequently found on cereals and processed grains; when it contaminates human food and animal feed it is often associated with another widespread contaminant, Deoxynivalenol. Following their ingestion, intestinal epithelial cells are exposed to concentrations of these trichothecenes high enough to cause mycotoxicosis.

Hydrocortisone modulates cholera toxin endocytosis by regulating immature enterocyte plasma membrane phospholipids.

Background & Aims: Diarrheal disease is a major cause of morbidity and mortality in infants and children worldwide. Evidence has indicated immature human enterocytes and their interaction with bacteria and enterotoxins may account for the noted increased susceptibility of neonates to diarrhea. Our aim was to characterize the developmental difference in cholera toxin (CT)-GM1-mediated endocytosis.

Luminal starch substrate "brake" on maltase-glucoamylase activity is located within the glucoamylase subunit.

The detailed mechanistic aspects for the final starch digestion process leading to effective alpha-glucogenesis by the 2 mucosal alpha-glucosidases, human sucrase-isomaltase complex (SI) and human maltase-glucoamylase (MGAM), are poorly understood. This is due to the structural complexity and vast variety of starches and their intermediate digestion products, the poorly understood enzyme-substrate interactions occurring during the digestive process, and the limited knowledge of the structure-function properties of SI and MGAM. Here we analyzed the basic catalytic properties of the N-terminal subunit of MGAM (ntMGAM) on the hydrolysis of glucan substrates and compared it with those of human native MGAM isolated by immunochemical methods.

Luminal substrate "brake" on mucosal maltase-glucoamylase activity regulates total rate of starch digestion to glucose.

Background: Starches are the major source of dietary glucose in weaned children and adults. However, small intestine alpha-glucogenesis by starch digestion is poorly understood due to substrate structural and chemical complexity, as well as the multiplicity of participating enzymes. Our objective was dissection of luminal and mucosal alpha-glucosidase activities participating in digestion of the soluble starch product maltodextrin (MDx).

Contribution of mucosal maltase-glucoamylase activities to mouse small intestinal starch alpha-glucogenesis.

Digestion of starch requires activities provided by 6 interactive small intestinal enzymes. Two of these are luminal endo-glucosidases named alpha-amylases. Four are exo-glucosidases bound to the luminal surface of enterocytes.

Lipopolysaccharide-induced human enterocyte tolerance to cytokine-mediated interleukin-8 production may occur independently of TLR-4/MD-2 signaling.

Intestinal epithelial cells (IEC) are constantly exposed to bacterial components, such as LPS, without triggering proinflammatory immune responses. This study demonstrates that chronic exposure of human-derived IEC to LPS induces tolerance to an endogenous inflammatory cytokine (IL-1beta) activated IL-8 response that occurs independently of TLR-4/MD-2 signaling. IL-8 production in response to activation by unrelated TNF-alpha and PMA signaling pathways is also inhibited, indicating a broad-spanning tolerance.

Involvement of TRAIL/TRAIL-receptors in human intestinal cell differentiation.

Despite the fact that tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) and its receptors (TRAIL-Rs) are expressed in intestinal mucosa, little is known about the biological role of this system in intestinal cell physiology. The expression of surface TRAIL and TRAIL-R1, -R2, -R3, -R4 were examined by flow cytometry in the immortalized human cell line tsFHI under culture conditions promoting growth or growth arrest and expression of differentiated traits. A progressive increase of surface TRAIL expression paralleled tsFHI differentiation, consistently with immunohistochemistry analysis showing an increase of TRAIL immunostaining along the crypt-villus axis in normal jejuneal mucosa.

p27(Kip1) is an inducer of intestinal epithelial cell differentiation.

Constant renewal of the intestinal epithelium is a highly coordinated process that has been subject to intense investigation, but its regulatory mechanisms are still essentially unknown. In this study, we have demonstrated that forced expression of the cyclin-dependent kinase inhibitors (CKIs) p27(Kip1) and p21(Cip1/WAF1) in human intestinal epithelial cells led to expression of differentiation markers at both the mRNA and protein levels. Cell differentiation was temporally dissociated from inhibition of retinoblastoma protein phosphorylation and growth arrest, already established 1 day after infection with recombinant adenoviruses.

Contribution of villous atrophy to reduced intestinal maltase in infants with malnutrition.

Background: It has been known for many years that small intestinal maltase activities are reduced in malnourished infants and in other patients with villous atrophy. The recent availability of human maltase-glucoamylase cDNA provides the opportunity to test the hypothesis that villous atrophy accounts for the reduced maltase enzyme activity in malnourished infants.

Methods: Mucosal biopsy specimens obtained for clinical evaluation of malnourished infants with poor responses to refeeding were examined by quantitative methods for enzyme activity and mRNA levels.

Glucocorticoids have pleiotropic effects on small intestinal crypt cells.

Glucocorticoids have long been known to accelerate maturation of the intestinal tract, but the molecular mechanisms that account for their physiological function in the epithelium remain poorly characterized. Using rat intestinal epithelial cell lines (IEC-6, IEC-17, and IEC-18) as models, we have characterized glucocorticoid receptors in crypt cells and documented striking morphological, ultrastructural, and functional alterations induced by these hormones in intestinal cells. They include arrest of growth, formation of tight junctions, appearance of long, slender microvilli, reorganization of the endoplasmic reticulum and trans-Golgi network, and downregulation of the cell cycle regulatory proteins cyclin-dependent kinase 6 and p27(Kip1).

Involvement of p21(WAF1/Cip1) and p27(Kip1) in intestinal epithelial cell differentiation.

Using the conditionally immortalized human cell line tsFHI, we have investigated the role of cyclin-dependent kinase inhibitors (CKIs) in intestinal epithelial cell differentiation. Expression of cyclins, cyclin-dependent kinases (Cdk), and CKIs was examined under conditions promoting growth, growth arrest, or expression of differentiated traits. Formation of complexes among cell cycle regulatory proteins and their kinase activities were also investigated.

Dissociation between growth arrest and differentiation in Caco-2 subclone expressing high levels of sucrase.

Growth arrest and cell differentiation are generally considered temporally and functionally linked phenomena in small intestinal crypt cells and colon tumor cell lines (Caco-2, HT-29). We have derived a Caco-2 subclone (NGI3) that deviates from such a paradigm. In striking contrast with the parental cells, proliferative and subconfluent NGI3 cells were found to express sucrase-isomaltase (SI) mRNA and to synthesize relatively high levels of SI, dipeptidyl peptidase IV, and aminopeptidase N (APN).

Cytocentrin is a Ral-binding protein involved in the assembly and function of the mitotic apparatus.

Cytocentrin is a cytosolic protein that transiently associates with the mitotic spindle poles in early prophase, and dissociates from them after completion of mitosis. Cloning of its cDNA demonstrated a high degree of homology with three proteins known to specifically interact with an activated form of Ral. Herein we demonstrate that overexpression of cytocentrin inhibits assembly of the mitotic spindle without affecting polymerization or distribution of interphase microtubules.

Human small intestinal maltase-glucoamylase cDNA cloning. Homology to sucrase-isomaltase.

It has been hypothesized that human mucosal glucoamylase (EC 3.2.1.

Cell dynamics and differentiation of conditionally immortalized human intestinal epithelial cells.

Background & Aims: Intestinal epithelial cell lines capable of differentiating in monolayer culture have been difficult to obtain, prompting the use of novel approaches including immortalization with oncogenes or tumor viruses. The aim of this study was to obtain conditionally immortalized human intestinal epithelial cells (temperature-sensitive fetal human intestinal [tsFHI] cells) and study their growth and differentiation capabilities.

Methods: Intestinal cells from human fetuses were transformed with a temperature-sensitive simian virus 40 large tumor antigen, cloned, and screened for expression of intestinal markers.

Effects of malnutrition on expression and activity of lactase in children.

Background & Aims: Many malnourished infants have reduced lactase specific activity in the small intestine. The aim of this study was to test the hypothesis that the hypolactasia of malnourished infants results from transcriptional suppression of lactase expression.

Methods: Biopsy specimens were studied from two groups of infants: 29 with malnutrition and 10 normally nourished controls with normal morphology and lactase activity.

Lactase phlorhizin hydrolase turnover in vivo in water-fed and colostrum-fed newborn pigs.

We have estimated the synthesis rates in vivo of precursor and brush-border (BB) polypeptides of lactase phlorhizin hydrolase (LPH) in newborn pigs fed with water or colostrum for 24h post partum. At the end of the feeding period, piglets were anaesthetized and infused intravenously for 3h with L-[4-3H]- phenylalanine. Blood and jejunal samples were collected at timed intervals.

Identification of a 102 kDa protein (cytocentrin) immunologically related to keratin 19, which is a cytoplasmically derived component of the mitotic spindle pole.

The mAb RK7, previously shown to recognize keratin 19, was also found to cross-react with a biologically unrelated 102 kDa protein, which becomes associated with the poles of the mitotic apparatus. This newly identified protein, called cytocentrin, is a stable cellular component, may be at least in part phosphorylated, and displays a cell cycle-dependent cellular localization. In interphase cells, it is diffusely distributed in the cytosol and shows no affinity for cytoplasmic microtubules.