Intestinal epithelial cell signalling and chronic inflammation: From the proteome to specific molecular mechanisms

Cytoskeletal Responses and Aif-1 Expression in Caco-2 Monolayers Exposed to Phorbol-12-Myristate-13-Acetate and Carnosine

The dis(re)organization of the cytoskeletal actin in enterocytes mediates epithelial barrier dys(re)function, playing a key role in modulating epithelial monolayer's integrity and remodeling under transition from physiological to pathological states. Here, by fluorescence-based morphological and morphometric analyses, we detected differential responses of cytoskeletal actin in intestinal epithelial Caco-2 cell monolayers at two different stages of their spontaneous differentiation, i.e., undifferentiated cells at 7 days post-seeding (dps) and differentiated enterocyte-like cells at 21 dps, upon challenge in vitro with the inflammation-mimicking stimulus of phorbol-12-myristate-13-acetate (PMA). In addition, specific responses were found in the presence of the natural dipeptide carnosine detecting its potential counteraction against PMA-induced cytoskeletal alterations and remodeling in differentiated Caco-2 monolayers. In such an experimental context, by both immunocytochemistry and Western blot assays in Caco-2 monolayers, we identified the expression of the allograft inflammatory factor 1 (AIF-1) as protein functionally related to both inflammatory and cytoskeletal pathways. In 21 dps monolayers, particularly, we detected variations of its intracellular localization associated with the inflammatory stimulus and its mRNA/protein increase associated with the differentiated 21 dps enterocyte-like monolayer compared to the undifferentiated cells.

KGF Is Delivered to Inflammatory and Induces the Epithelial Hyperplasia in Trinitrobenzene Sulfonic Acid-Induced Ulcerative Colitis Rats

Introduction

KGF-modified MSCs can promote the repair of spinal cord injury and pulmonary fibrosis injury in rats. However, the effect of KGF-modified MSCs on UC rats is unclear. We aimed to explore the therapeutic effect and possible mechanism of KGF gene-modified MSCs on trinitrobenzene sulfonic acid (TNBS)-induced UC rats.

Methods

The lentivirus-mediated KGF gene was introduced into bone marrow MSCs of male rats. Female SD rats were induced to establish a UC model by TNBS. Untreated MSCs, MSCs carrying empty vectors (MSCs-vec) or MSCs carrying KGF gene (MSCs-KGF) were transplanted into UC rats by tail vein injection.

Results

Significantly high expression of KGF was observed in the intestinal tissues of the MSCs-KGF group. Compared with the challenged control group, the DAI score, CMDI score and TDI score of the MSCs group, MSCs-vec group and MSCs-KGF group were markedly lower. Treatment with MSCs obviously promoted the expression of claudin-1 and PCNA in intestinal tissues of UC rats. Simultaneously, compared with the challenged control group, the levels of TNF-α, IL-6 and IL-8 in the intestinal tissues of the MSCs groups were significantly decreased, while the levels of IL-10 were significantly increased. Most importantly, we found that MSCs-KGF significantly improved colonic morphology and tissue damage and inflammation in UC rats compared with MSCs and MSCs-vec. Further analysis showed that MSCs-KGF clearly promoted phosphorylation of PI3K and Akt and inhibited nuclear translocation of NF-κB in intestinal tissues of UC rats.

Discussion

MSCs, especially KGF-modified MSCs, can improve colonic tissue damage in UC rats by promoting intestinal epithelial cell proliferation and reducing colonic inflammatory response, which may be related to activation of PI3K/Akt pathway and inhibition of NF-κB activation.

Impact of high dietary plant protein with or without marine ingredients in gut mucosa proteome of gilthead seabream (Sparus aurata, L.)

The digestive tract, particularly the intestine, represents one of the main sites of interactions with the environment, playing the gut mucosa a crucial role in the digestion and absorption of nutrients, and in the immune defence. Previous researches have proven that the fishmeal replacement by plant sources could have an impact on the intestinal status at both digestive and immune level, compromising relevant productive parameters, such as feed efficiency, growth or survival. In order to evaluate the long-term impact of total fishmeal replacement on intestinal mucosa, the gut mucosa proteome was analysed in fish fed with a fishmeal-based diet, against plant protein-based diets with or without alternative marine sources inclusion. Total fishmeal replacement without marine ingredients inclusion, reported a negative impact in growth and biometric parameters, further an altered gut mucosa proteome. However, the inclusion of a low percentage of marine ingredients in plant protein-based diets was able to maintain the growth, biometrics parameters and gut mucosa proteome with similar values to FM group. A total fishmeal replacement induced a big set of underrepresented proteins in relation to several biological processes such as intracellular transport, assembly of cellular macrocomplex, protein localization and protein catabolism, as well as several molecular functions, mainly related with binding to different molecules and the maintenance of the cytoskeleton structure. The set of downregulated proteins also included molecules which have a crucial role in the maintenance of the normal function of the enterocytes, and therefore, of the epithelium, including permeability, immune and inflammatory response regulation and nutritional absorption. Possibly, the amino acid imbalance presented in VM diet, in a long-term feeding, may be the main reason of these alterations, which can be prevented by the inclusion of 15% of alternative marine sources. SIGNIFICANCE: Long-term feeding with plant protein based diets may be considered as a stress factor and lead to a negative impact on digestive and immune system mechanisms at the gut, that can become apparent in a reduced fish performance. The need for fishmeal replacement by alternative ingredients such as plant sources to ensure the sustainability of the aquaculture sector has led the research assessing the intestinal status of fish to be of increasing importance. This scientific work provides further knowledge about the proteins and biologic processes altered in the gut in response to plant protein based diets, suggesting the loss of part of gut mucosa functionality. Nevertheless, the inclusion of alternative marine ingredients was able to reverse these negative effects, showing as a feasible option to develop sustainable aquafeeds.

Molecular Mechanisms and Pathways as Targets for Cancer Prevention and Progression with Dietary Compounds

A unique feature of bioactive food ingredients is their broad antioxidant function. Antioxidants having a wide spectrum of chemical structure and activity beyond basic nutrition; display different health benefits by the prevention and progression of chronic diseases. Functional food components are capable of enhancing the natural antioxidant defense system by scavenging reactive oxygen and nitrogen species, protecting and repairing DNA damage, as well as modulating the signal transduction pathways and gene expression. Major pathways affected by bioactive food ingredients include the pro-inflammatory pathways regulated by nuclear factor kappa B (NF-κB), as well as those associated with cytokines and chemokines. The present review summarizes the importance of plant bioactives and their roles in the regulation of inflammatory pathways. Bioactives influence several physiological processes such as gene expression, cell cycle regulation, cell proliferation, cell migration, etc., resulting in cancer prevention. Cancer initiation is associated with changes in metabolic pathways such as glucose metabolism, and the effect of bioactives in normalizing this process has been provided. Initiation and progression of inflammatory bowel diseases (IBD) which increase the chances of developing of colorectal cancers can be downregulated by plant bioactives. Several aspects of the potential roles of microRNAs and epigenetic modifications in the development of cancers have also been presented.

The role of dose rate in radiation cancer risk: evaluating the effect of dose rate at the molecular, cellular and tissue levels using key events in critical pathways following exposure to low LET radiation

PURPOSE

This review evaluates the role of dose rate on cell and molecular responses. It focuses on the influence of dose rate on key events in critical pathways in the development of cancer. This approach is similar to that used by the U.S. EPA and others to evaluate risk from chemicals. It provides a mechanistic method to account for the influence of the dose rate from low-LET radiation, especially in the low-dose region on cancer risk assessment. Molecular, cellular, and tissues changes are observed in many key events and change as a function of dose rate. The magnitude and direction of change can be used to help establish an appropriate dose rate effectiveness factor (DREF).

CONCLUSIONS

Extensive data on key events suggest that exposure to low dose-rates are less effective in producing changes than high dose rates. Most of these data at the molecular and cellular level support a large (2-30) DREF. In addition, some evidence suggests that doses delivered at a low dose rate decrease damage to levels below that observed in the controls. However, there are some data human and mechanistic data that support a dose-rate effectiveness factor of 1. In summary, a review of the available molecular, cellular and tissue data indicates that not only is dose rate an important variable in understanding radiation risk but it also supports the selection of a DREF greater than one as currently recommended by ICRP ( 2007 ) and BEIR VII (NRC/NAS 2006 ).

Metabolic phenotyping of an adoptive transfer mouse model of experimental colitis and impact of dietary fish oil intake

Inflammatory bowel diseases are acute and chronic disabling inflammatory disorders with multiple complex etiologies that are not well-defined. Chronic intestinal inflammation has been linked to an energy-deficient state of gut epithelium with alterations in oxidative metabolism. Plasma-, urine-, stool-, and liver-specific metabonomic analyses are reported in a naïve T cell adoptive transfer (AT) experimental model of colitis, which evaluated the impact of long-chain n-3 polyunsaturated fatty acid (PUFA)-enriched diet. Metabolic profiles of AT animals and their controls under chow diet or fish oil supplementation were compared to describe the (i) consequences of inflammatory processes and (ii) the differential impact of n-3 fatty acids. Inflammation was associated with higher glycoprotein levels (related to acute-phase response) and remodeling of PUFAs. Low triglyceride levels and enhanced PUFA levels in the liver suggest activation of lipolytic pathways that could lead to the observed increase of phospholipids in the liver (including plasmalogens and sphingomyelins). In parallel, the increase in stool excretion of most amino acids may indicate a protein-losing enteropathy. Fecal content of glutamine was lower in AT mice, a feature exacerbated under fish oil intervention that may reflect a functional relationship between intestinal inflammatory status and glutamine metabolism. The decrease in Krebs cycle intermediates in urine (succinate, α-ketoglutarate) also suggests a reduction in the glutaminolytic pathway at a systemic level. Our data indicate that inflammatory status is related to this overall loss of energy homeostasis.

Sicilian pistachio (Pistacia vera L.) nut inhibits expression and release of inflammatory mediators and reverts the increase of paracellular permeability in IL-1β-exposed human intestinal epithelial cells

BACKGROUND

Dietary approaches to control inflammatory bowel diseases (IBD) may include proanthocyanidin-rich foods. Our previous research showed that a hydrophilic extract from Sicilian pistachio nut (HPE) contains substantial amounts of proanthocyanidins and possesses anti-inflammatory activities.

PURPOSE

We studied the effects of HPE and of its polymeric proanthocyanidin fraction (PPF) in a cell model that simulated some conditions of IBD, consisting of interleukin (IL)-1β-stimulated Caco-2 cells.

METHODS

HPE was prepared by Pistacia vera L. nuts, and PPF was isolated from HPE by adsorbance chromatography. Proanthocyanidins were quantified as anthocyanidins after acidic hydrolysis. Differentiated Caco-2 cells were pre-incubated with HPE or PPF and then were exposed to IL-1β. Cell viability and parameters associated with nuclear factor-κB (NF-κB) activation were assayed. Adsorption of polymeric proanthocyanidins to the cell membrane was investigated by transepithelial electrical resistance (TEER) measurements.

RESULTS

HPE decreased prostaglandin (PG)E2 production, IL-6 and IL-8 release, and cyclooxygenase (COX)-2 expression. HPE also inhibited the increase in paracellular permeability and reduced NF-κB activation. Polymeric proanthocyanidins, tested at a concentration comparable with their content in HPE, produced effects comparable to HPE. Finally, cell exposure to PPF increases TEER of the epithelial monolayers.

CONCLUSION

Our results provide evidence that pistachio nut components inhibit inflammatory response of intestinal epithelial cells in vitro and indicate polymeric proanthocyanidins as the major bioactive nut components. The protection implies inhibition of NF-κB activation and occurs in parallel with the adsorption of polymeric proanthocyanidins to cell membrane. Our findings suggest that intake of small amounts of pistachio nut can exert beneficial effects to gastrointestinal pathophysiology.

MicroRNAs: New therapeutic targets for intestinal barrier dysfunction

Defects in intestinal barrier function characterized by an increase in intestinal permeability contribute to intestinal inflammation. Growing evidence has shown that an increase in intestinal permeability has a pathogenic role in diseases such as inflammatory bowel disease (IBD) and celiac disease, and functional bowel disorders such as irritable bowel syndrome. Therefore, clarification of the inflammatory responses, the defense pathway and the corresponding regulatory system is essential and may lead to the development of new therapies. MicroRNAs (miRNAs) are small (19-22 nt) noncoding RNA molecules that regulate genes at the post-transcriptional level by base-pairing to specific messenger RNAs for degradation to repress translation. Recent studies suggested that miRNAs are important in the immune response and mediate a critical role in multiple immune response-related disorders. Based on these discoveries, attention has been focused on understanding the role of miRNAs in regulating intestinal barrier dysfunction, especially in IBD. Here, we provide a review of the most recent state-of-the-art research on miRNAs in intestinal barrier dysfunction.

Anti-inflammatory effects of the nicotinergic peptides SLURP-1 and SLURP-2 on human intestinal epithelial cells and immunocytes

A search for novel and more efficient therapeutic modalities of inflammatory bowel disease (IBD) is one of the most important tasks of contemporary medicine. The anti-inflammatory action of nicotine in IBD might be therapeutic, but its toxicity due to off-target and nonreceptor effects limited its use and prompted a search for nontoxic nicotinergic drugs. We tested the hypothesis that SLURP-1 and -2—the physiological nicotinergic substances produced by the human intestinal epithelial cells (IEC) and immunocytes—can mimic the anti-inflammatory effects of nicotine. We used human CCL-241 enterocytes, CCL-248 colonocytes, CCRF-CEM T-cells, and U937 macrophages. SLURP-1 diminished the TLR9-dependent secretion of IL-8 by CCL-241, and IFNγ-induced upregulation of ICAM-1 in both IEC types. rSLURP-2 inhibited IL-1β-induced secretion of IL-6 and TLR4- and TLR9-dependent induction of CXCL10 and IL-8, respectively, in CCL-241. rSLURP-1 decreased production of TNFα by T-cells, downregulated IL-1β and IL-6 secretion by macrophages, and moderately upregulated IL-10 production by both types of immunocytes. SLURP-2 downregulated TNFα and IFNγR in T-cells and reduced IL-6 production by macrophages. Combining both SLURPs amplified their anti-inflammatory effects. Learning the pharmacology of SLURP-1 and -2 actions on enterocytes, colonocytes, T cells, and macrophages may help develop novel effective treatments of IBD.

Metabolic endotoxemia: a molecular link between obesity and cardiovascular risk

Obesity is associated with significantly increased cardiovascular (CV) risk and mortality. Several molecular mechanisms underlying this association have been implied, among which the intestinal barrier has gained a growing interest. In experimental models of obesity, significant alterations in the intestinal barrier lead to increased intestinal permeability, favoring translocation of microbiome-derived lipopolysaccharide to the bloodstream. This has been shown to result in a two- to threefold increase in its serum concentrations, a threshold named 'metabolic endotoxemia' (ME). ME may trigger toll-like receptor 4-mediated inflammatory activation, eliciting a chronic low-grade proinflammatory and pro-oxidative stress status, which may result in high CV risk and target-organ damage. In this review, we discuss the potential molecular implications of ME on several CV risk factors, such as obesity, insulin resistance, dyslipidemia, and oxidative stress, as well as its potential impact on the development of CV target-organ disease.

Intestinal proteome changes during infant necrotizing enterocolitis

BACKGROUND

Changes in the intestinal and colonic proteome in patients with necrotizing enterocolitis (NEC) may help to characterize the disease pathology and identify new biomarkers and treatment targets for NEC.

METHODS

Using gel-based proteomics, proteins in NEC-affected intestinal and colonic sections were compared with those in adjacent, near-normal tissue sections within the same patients. Western blot and immunohistochemistry were applied to crossvalidate proteomic data and histological location of some selected proteins.

RESULTS

Thirty proteins were identified with differential expression between necrotic and vital small-intestine sections and 23 proteins were identified for colon sections. Five proteins were similarly affected in the small intestine and colon: histamine receptors (HRs), actins, globins, immunoglobulin, and antitrypsin. Two heat shock proteins (HSPs) were affected in the small intestine. Furthermore, proteins involved in antioxidation, angiogenesis, cytoskeleton formation, and metabolism were affected. Finally, secretory proteins such as antitrypsin, fatty-acid binding protein 5, and haptoglobin differed between NEC-affected and vital tissues.

CONCLUSION

NEC progression affects different pathways in the small intestine and colon. HSPs may play an important role, especially in the small intestine. The identified secretory proteins should be investigated as possible circulating markers of NEC progression in different gut regions.

Heme modulates intestinal epithelial cell activation: involvement of NADPHox-derived ROS signaling

In many gut chronic inflammatory conditions, intestinal epithelium (IE) is deprived of the protection of the mucus secreted by IE-specialized cells. In these events, bleeding and subsequent lysis of erythrocytes are common. This may lead to the release of high amounts of heme in the intestinal lumen, which interacts with IE. Previous works from our group have shown that heme itself is a proinflammatory molecule, activating a number of phlogistic signaling events in a nicotinamide adenine dinucleotide phosphate oxidase (NADPHox)-dependent manner. In this study, we aim to evaluate the effects of heme upon a well-established nontransformed small intestine epithelial cell lineage (IEC 6). Our results show that free heme evokes intracellular reactive oxygen species (ROS) production by IEC 6 cells, which is inhibited both by pharmacological inhibition with diphenyleneiodonium (10 μM), a NADPHox inhibitor, and small interfering RNA-mediated suppression of NOX1, a constitutive NADPHox isoform present in intestinal epithelial cells. Focal adhesion kinase phosphorylation and actin cytoskeleton polymerization are also induced by heme in a NADPHox-dependent manner. Heme increases monolayer permeability and redistributes key modulators of cell-cell adhesion as zona occludens-1 and E-cadherin proteins via NADPHox signaling. Heme promotes IEC 6 cell migration and proliferation, phenomena also regulated by NADPHox-derived ROS. Heme, in NADPHox-activating concentrations, is able to induce mRNA expression of IL-6, a cytokine implicated in inflammatory and tumorigenic responses. These data indicate a prominent role for heme-derived signaling in the pathophysiology of intestinal mucosa dysfunction and address an important role of NADPHox activity on the pathogenesis of intestinal inflammatory conditions.

Nutrigenomics and nutrigenetics in inflammatory bowel diseases

Inflammatory bowel diseases (IBD) including ulcerative colitis and Crohn's disease are chronically relapsing, immune-mediated disorders of the gastrointestinal tract. A major challenge in the treatment of IBD is the heterogenous nature of these pathologies. Both, ulcerative colitis and Crohn's disease are of multifactorial etiology and feature a complex interaction of host genetic susceptibility and environmental factors such as diet and gut microbiota. Genome-wide association studies identified disease-relevant single-nucleotide polymorphisms in approximately 100 genes, but at the same time twin studies also clearly indicated a strong environmental impact in disease development. However, attempts to link dietary factors to the risk of developing IBD, based on epidemiological observations showed controversial outcomes. Yet, emerging high-throughput technologies implying complete biological systems might allow taking nutrient-gene interactions into account for a better classification of patient subsets in the future. In this context, 2 new scientific fields, "nutrigenetics" and "nutrigenomics" have been established. "Nutrigenetics," studying the effect of genetic variations on nutrient-gene interactions and "Nutrigenomics," describing the impact of nutrition on physiology and health status on the level of gene transcription, protein expression, and metabolism. It is hoped that the integration of both research areas will promote the understanding of the complex gene-environment interaction in IBD etiology and in the long-term will lead to personalized nutrition for disease prevention and treatment. This review briefly summarizes data on the impact of nutrients on intestinal inflammation, highlights nutrient-gene interactions, and addresses the potential of applying "omic" technologies in the context of IBD.

Comparative analysis of inflamed and non-inflamed colon biopsies reveals strong proteomic inflammation profile in patients with ulcerative colitis

BACKGROUND

Accurate diagnostic and monitoring tools for ulcerative colitis (UC) are missing. Our aim was to describe the proteomic profile of UC and search for markers associated with disease exacerbation. Therefore, we aimed to characterize specific proteins associated with inflamed colon mucosa from patients with acute UC using mass spectrometry-based proteomic analysis.

METHODS

Biopsies were sampled from rectum, sigmoid colon and left colonic flexure from twenty patients with active proctosigmoiditis and from four healthy controls for proteomics and histology. Proteomic profiles of whole colonic biopsies were characterized using 2D-gel electrophoresis, and peptide mass fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was applied for identification of differently expressed protein spots.

RESULTS

A total of 597 spots were annotated by image analysis and 222 of these had a statistically different protein level between inflamed and non-inflamed tissue in the patient group. Principal component analysis clearly grouped non-inflamed samples separately from the inflamed samples indicating that the proteomic signature of colon mucosa with acute UC is strong. Totally, 43 individual protein spots were identified, including proteins involved in energy metabolism (triosephosphate isomerase, glycerol-3-phosphate-dehydrogenase, alpha enolase and L-lactate dehydrogenase B-chain) and in oxidative stress (superoxide dismutase, thioredoxins and selenium binding protein).

CONCLUSIONS

A distinct proteomic profile of inflamed tissue in UC patients was found. Specific proteins involved in energy metabolism and oxidative stress were identified as potential candidate markers for UC.

Altered endoplasmic reticulum stress affects translation in inactive colon tissue from patients with ulcerative colitis

BACKGROUND & AIMS

Ulcerative colitis (UC) is a chronic inflammatory disorder that affects the colonic epithelium. Epidemiology studies indicate an environmental component is involved in pathogenesis, although the primary changes in the digestive epithelium that cause an uncontrolled inflammatory response are not known. Animal studies have shown that altered endoplasmic reticulum (ER) stress response initiates intestinal inflammation in epithelial tissues, but abnormalities associated with ER stress have not been identified in patients with UC.

METHODS

Using immunoblotting, real-time polymerase chain reaction, immunohistochemistry, and immunofluorescence analyses, we assessed ER stress signaling in uninflammed colonic mucosa from patients with UC and controls. Genome-wide microarray analysis of actively translated polysome-bound messenger RNA was performed using samples of unaffected mucosa from patients with UC, and data were compared with those from controls.

RESULTS

Inositol-requiring kinase and activating transcription factor signaling pathways were activated in inactive colonic epithelium from patients with UC; these mediate proinflammatory and regenerative responses. Blocking phosphorylation of the translation initiation factor 2 (eIF2α), which mediates the integrated stress response, deregulated initiation of translation and reduced the numbers of stress granules in colonic epithelial cells from patients with UC. Genome-wide microarray analysis of actively translated, polysome-bound messenger RNA from patients revealed changes in protein translation that altered colonic epithelial barrier function (levels of detoxification and antioxidant enzymes and proteins that regulate the cell cycle, cell-cell adhesion, and secretion), compared with controls.

CONCLUSIONS

Colonic mucosa samples from patients with UC have defects in the eIF2α pathway that controls protein translation and the cell stress response. This pathway might be investigated to identify new therapeutic targets for patients with UC.

Structure-function analysis of the tertiary bile acid TUDCA for the resolution of endoplasmic reticulum stress in intestinal epithelial cells

Inflammatory bowel diseases (IBD) are chronically relapsing and immune-mediated disorders of the gastrointestinal tract. Endoplasmic reticulum (ER) stress mechanisms in the epithelium have been demonstrated to be implemented into the pathogenesis of intestinal inflammation. Chemical chaperones have been demonstrated to exhibit beneficial effects in various diseases associated with ER stress mechanisms by prohibiting the unfolded protein response (UPR). In a structure-function analysis, we tested the potential of the conjugated bile salt sodium tauroursodeoxycholate (TUDCA), naturally present in the small bowel, to resolve ER stress in intestinal epithelial cells. TUDCA efficiently inhibited the expression of UPR dependent genes like GRP78 triggered by the ER stressor tunicamycin in the small intestinal epithelial cell line Mode-K. TUDCA inhibited upstream signaling events in all three branches of the UPR cascade and diminished binding of UPR activated transcription factors to the grp78 promoter. A structure-function analysis revealed that UDCA but not its conjugation partner taurine, known as a chemical chaperone, is responsible for the inhibition of GRP78 induction and that UDCA is 10 times more effective than its taurine conjugate. This inhibitory effect was confirmed in a cell free assay, where TUDCA and UDCA but not taurine effectively inhibited the aggregation of thermally denatured BSA. We conclude that TUDCA and UDCA are potent anti-aggregants for the resolution of ER stress in intestinal epithelial cells and should be considered as a potential drug target to resolve ER stress mechanisms underlying the pathology of IBD.

Dietary β-glucan regulates the levels of inflammatory factors, inflammatory cytokines, and immunoglobulins in interleukin-10 knockout mice

β-Glucan is known to have anti-inflammatory properties, and several studies have demonstrated the beneficial effects of dietary β-glucan on inflammatory bowel disease (IBD). However, it is unknown how β-glucan mediates its protective effects on IBD. Therefore, we used a well-established mouse model for IBD, interleukin (IL)-10(-/-) mice, to explore the protective effects of β-glucan on IBD-like symptoms caused by IL-10 deficiency. The mice were divided into two groups: IL-10(-/-) and IL-10(-/-) + β-glucan treatment groups. IL-10(-/-) mice treated with dietary β-glucan exhibited less inflammation within the colon. The levels of immunoglobulins A and E were lower in the serum, spleen, mesenteric lymph nodes, and Peyer's patches in the IL-10(-/-) mice compared with the IL-10(-/-) + β-glucan mice. Also, the expression of pro-inflammatory cytokines was lower in the IL-10(-/-) + β-glucan mice compared with the IL-10(-/-) mice. Histological analysis also revealed that administration of dietary β-glucan in IL-10(-/-) mice reduced colonic tissue damage. Finally, the expression of the pro-inflammatory cytokine tissue necrosis factor-α was significantly lower with dietary β-glucan treatment in IL-10(-/-) mice. In conclusion, dietary β-glucan reduces the inflammation associated with IBD caused by IL-10 deficiency.

Anti-inflammatory effects of dietary phenolic compounds in an in vitro model of inflamed human intestinal epithelium

Phenolic compounds (PCs) are considered to possess anti-inflammatory properties and therefore were proposed as an alternative natural approach to prevent or treat chronic inflammatory diseases. However their effects are not fully understood, particularly at the intestinal level. To further understand their mode of action at the molecular level during intestinal inflammation, an in vitro model of inflamed human intestinal epithelium was established. Different representative dietary PCs, i.e. resveratrol, ellagic and ferulic acids, curcumin, quercetin, chrysin, (-)-epigallocatechin-3-gallate (EGCG) and genistein, were selected. To mimic intestinal inflammation, differentiated Caco-2 cells cultivated in bicameral inserts, in a serum-free medium, were treated with a cocktail of pro-inflammatory substances: interleukin (IL)-1β, tumor necrosis factor-α, interferon-γ and lipopolysaccharides. The inflammatory state was characterized by a leaky epithelial barrier (attenuation of the transepithelial electrical resistance) and by an over-expression at the mRNA and protein levels for pro-inflammatory markers, i.e. IL-6, IL-8 and monocyte chemoattractant protein-1 (MCP-1), quantified by ELISA and by gene expression analysis using a low-density array allowing the evaluation of expression level for 46 genes relevant of the intestinal inflammation and functional metabolism. Treatment with PCs, used at a realistic intestinal concentration, did not affect cell permeability. In inflamed cells, the incubation with genistein reduced the IL-6 and MCP-1 overproduction, to ca. 50% of the control, whereas EGCG provoked a decrease in the IL-6 and IL-8 over-secretion, by 50 and 60%, respectively. This occurred for both flavonoids without any concomitant inhibition of the corresponding mRNA expression. All the PCs generated a specific gene expression profile, with genistein the most efficient in the downregulation of the expression, or over-expression, of inflammatory genes notably those linked to the arachidonic metabolism pathway. In conclusion, this study provides evidence that genistein and EGCG downregulate the inflammatory response in inflamed intestinal epithelial cells by a pathway implicating largely a post-transcriptional regulatory mechanism.

Nutrigenomics and IBD: the intestinal microbiota at the cross-road between inflammation and metabolism

Nutrition-related factors together with components of the gut-associated microbial ecosystem (gut microbiota) emerge as prime environmental triggers for the development and modification of lifestyle-related chronic diseases including chronic inflammatory disorders of the gastro-intestinal tract such as Crohn's disease and ulcerative colitis. Although a variety of susceptibility genes were identified in genome-wide association studies, the impact of environmental factors in initiating or promoting the development of these complex diseases are unknown. Nutrigenomics is a transdisciplinary approach to understand the subtle but contentious impact of nutrition and/or microbes as prime environmental triggers in shaping the dynamic range between health and diseases. Profiling technologies such as transcriptomics, proteomics, and metabonomics at the interface of the host's genetic make-up and its metabolic phenotype are implemented to identify cellular and molecular targets to develop novel hypothesise with respect to the functional role of diet and gut bacteria in modulating chronic degenerative diseases including inflammatory bowel disease.

Cytoskeletal regulation of epithelial barrier function during inflammation

Increased epithelial permeability is a common and important consequence of mucosal inflammation that results in perturbed body homeostasis and enhanced exposure to external pathogens. The integrity and barrier properties of epithelial layers are regulated by specialized adhesive plasma membrane structures known as intercellular junctions. It is generally believed that inflammatory stimuli increase transepithelial permeability by inducing junctional disassembly. This review highlights molecular events that lead to disruption of epithelial junctions during inflammation. We specifically focus on key mechanisms of junctional regulation that are dependent on reorganization of the perijunctional F-actin cytoskeleton. We discuss critical roles of myosin-II-dependent contractility and actin filament turnover in remodeling of the F-actin cytoskeleton that drive disruption of epithelial barriers under different inflammatory conditions. Finally, we highlight signaling pathways induced by inflammatory mediators that regulate reorganization of actin filaments and junctional disassembly in mucosal epithelia.

The polymorphism rs3024505 proximal to IL-10 is associated with risk of ulcerative colitis and Crohns disease in a Danish case-control study

Background

Crohns disease (CD) and ulcerative colitis (UC) are characterized by a dysregulated inflammatory response to normal constituents of the intestinal flora in the genetically predisposed host. Heme oxygenase-1 (HO-1/HMOX1) is a powerful anti-inflammatory and anti-oxidant enzyme, whereas the pro-inflammatory interleukin 1β (IL-1β/IL1B) and anti-inflammatory interleukin 10 (IL-10/IL10) are key modulators for the initiation and maintenance of inflammation. We investigated whether single nucleotide polymorphisms (SNPs) in the IL-1β, IL-10, and HO-1 genes, together with smoking, were associated with risk of CD and UC.

Methods

Allele frequencies of the IL-1β T-31C (rs1143627), and IL-10 rs3024505, G-1082A (rs1800896), C-819T (rs1800871), and C-592A (rs1800872) and HO-1 A-413T (rs2071746) SNPs were assessed using a case-control design in a Danish cohort of 336 CD and 498 UC patients and 779 healthy controls. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated by logistic regression models.

Results

Carriers of rs3024505, a marker polymorphism flanking the IL-10 gene, were at increased risk of CD (OR = 1.40, 95% CI: 1.06-1.85, P = 0.02) and UC (OR = 1.43, 95% CI: 1.12-1.82, P = 0.004) and, furthermore, with risk of a diagnosis of CD and UC at young age (OR = 1.47, 95% CI: 1.10-1.96) and OR = 1.35, 95% CI: 1.04-1.76), respectively). No association was found between the IL-1β, IL-10 G-1082A, C-819T, C-592A, and HO-1 gene polymorphisms and CD or UC. No consistent interactions between smoking status and CD or UC genotypes were demonstrated.

Conclusions

The rs3024505 marker polymorphism flanking the IL-10 gene was significantly associated with risk of UC and CD, whereas no association was found between IL-1β or HO-1 gene polymorphisms and risk of CD and UC in this Danish study, suggesting that IL-10, but not IL-1β or HO-1, has a role in IBD etiology in this population.

Gut microbiota and probiotics in modulation of epithelium and gut-associated lymphoid tissue function

The intestinal tract mucosa is exposed to a vast number of environmental antigens and a large community of commensal bacteria. The mucosal immune system has to provide both protection against pathogens and tolerance to harmless bacteria. Immune homeostasis depends on the interaction of indigenous commensal and transient bacteria (probiotics) with various components of the epithelium and the gut-associated lymphoid tissue. Herein, an update is given of the mechanisms by which the gut microbiota and probiotics are translocated through the epithelium, sensed via pattern-recognition receptors, and activate innate and adaptive immune responses.

Antibiotics and probiotics in chronic pouchitis: A comparative proteomic approach

AIM: To profile protein expression in mucosal biopsies from patients with chronic refractory pouchitis following antibiotic or probiotic treatment, using a comparative proteomic approach.

METHODS: Two-dimensional polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry were used to characterize the changes related to antibiotic therapy in the protein expression profiles of biopsy samples from patients with chronic refractory pouchitis. The same proteomic approach was applied to identify differentially expressed proteins in the non-inflamed pouch before and after probiotic administration.

RESULTS: In the first set of 2D gels, 26 different proteins with at least 2-fold changes in their expression levels between the pouchitis condition and antibiotic-induced remission were identified. In the second set of analysis, the comparison between mucosal biopsy proteomes in the normal and probiotic-treated pouch resulted in 17 significantly differently expressed proteins. Of these, 8 exhibited the same pattern of deregulation as in the pouchitis/pouch remission group.

CONCLUSION: For the first time, 2D protein maps of mucosal biopsies from patients with ileal pouch-anal anastomosis were provided, and differentially expressed proteins following antibiotic/probiotic treatment were identified.

Antagonistic effects of aspirin and folic acid on inflammation markers and subsequent risk of recurrent colorectal adenomas

The Aspirin/Folate Polyp Prevention Trial found that aspirin, but not folic acid, reduced recurrence of colorectal adenomas. This study examined whether treatment effects on inflammation markers explained the trial results. The trial had a factorial design with three aspirin (placebo, 81, and 325 mg/d) and two folic acid (placebo and 1 mg/d) groups. There were 884 subjects who had colonoscopic evaluation for adenomas at year 3 and plasma levels of C-reactive protein (CRP), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), soluble TNF receptor type II (sTNF-R2), and IL-1 receptor antagonist (IL-1Ra) measured at baseline and year 3. Among individuals not receiving folic acid, there was a 4% decrease (mean ratio of year 3 to baseline levels = 0.96, 95% confidence interval [CI] = 0.82 to 1.14) in CRP for a period of 3 years in the 325 mg of aspirin group vs a 20% increase (mean ratio = 1.20, 95% CI = 1.03 to 1.41) in the placebo group (P = .027). By contrast, the reverse was observed among individuals who also received folic acid (P(interaction) = .013). Changes in inflammation markers were not associated with adenoma recurrence. Low-dose aspirin (325 mg/d) is beneficial in stabilizing CRP levels, which may be abrogated by folate. Nevertheless, inflammation markers do not mediate the chemopreventive effect of aspirin on colorectal adenomas.

Dietary polyphenols can modulate the intestinal inflammatory response

Inflammatory bowel diseases (IBD) arise from multiple causes, including environmental factors, gut microflora, immunity, and genetic predispositions. In the course of IBD, immune homeostasis and intestinal mucosa barrier integrity are impaired. Among natural preventive treatments that have been identified to date, polyphenols appear as promising candidates. They have been shown to protect against several diseases, including cardiovascular diseases and cancers, and they have anti-inflammatory properties in non-intestinal models. This paper will review the literature that has described to date some effects of polyphenols on intestinal inflammation. Studies, conducted using in vivo and in vitro models, provide evidence that pure polyphenolic compounds and natural polyphenolic plant extracts can modulate intestinal inflammation.

Intestinal epithelial cell proteome from wild-type and TNFDeltaARE/WT mice: effect of iron on the development of chronic ileitis

Environmental factors substantially contribute to the development of chronic intestinal inflammation in the genetically susceptible host. Nutritional components like iron may act as pro-oxidative mediators affecting inflammatory processes and cell stress mechanisms. To better characterize effects of dietary iron on epithelial cell responses under the pathological conditions of chronic intestinal inflammation, we characterized the protein expression profile (proteome) in primary intestinal epithelial cells (IEC) from iron-adequate and low-iron fed wild-type (WT) and TNFDeltaARE/WT mice. We performed all possible comparisons between the 4 groups according to genotype or diet. Histological analysis of iron-adequate fed TNFDeltaARE/WT mice (approximately 0.54 mg of iron/day) revealed severe ileal inflammation with a histopathology score of 8.3+/-0.91 (score range from 0-12). Interestingly, low-iron fed mice (approximately 0.03 mg of iron/day) were almost completely protected from the development of inflammatory tissue destruction (histopathology score of 2.30+/-0.73). In total, we identified 74 target proteins with significantly altered steady state expression levels in primary IEC using 2D-gel electrophoresis (2D SDS-PAGE) and peptide mass fingerprinting via MALDI-TOF mass spectrometry (MS). Interestingly, the overlap between the comparison of iron-adequate fed WT and TNFDeltaARE/WT mice (inflamed conditions) and the comparison between the iron-adequate and iron-low fed TNFDeltaARE/WT mice (absence of inflammation) revealed 4 contrarily regulated proteins including aconitase 2, catalase, intelectin 1 and fumarylacetoacetate hydrolase (FAH). These proteins are associated with energy homeostasis, host defense, oxidative and endoplasmic reticulum (ER) stress responses. In conclusion, the iron-low diet affected the epithelial cell proteome and inhibited the development of chronic intestinal inflammation, suggesting a critical role for nutritional factors in the pathogenesis of IBD.

Metabolic assessment of gradual development of moderate experimental colitis in IL-10 deficient mice

Evidence has linked genetic predisposition and environmental exposures to the worldwide pandemic of inflammatory bowel diseases (IBD), but underlying biochemical events remain largely undefined. Here, we studied the gradual development of colitis in Interleukin 10 deficient mice using a combination of (i) histopathological analysis of intestinal sections, (ii) metabolic profiling of blood plasma, and (iii) measurement of plasma inflammatory biomarkers. Data integration using chemometric tools, including Independent Component Analysis, provided a new strategy for measuring and mapping the metabolic effects associated with the development of intestinal inflammation at the age of 1, 8, 16, and 24 weeks. Chronic inflammation appeared at 8 weeks and onward, and was associated with altered cecum and colon morphologies and increased inflammatory cell infiltration into the mucosa and the submucosa. Blood plasma profiles provided additional evidence of loss of energy homeostasis, impaired metabolism of lipoproteins and glycosylated proteins. In particular, IL-10-/-mice were characterized by decreased levels of VLDL and increased concentrations of LDL and polyunsaturated fatty acids, which are related to the etiology of IBD. Moreover, higher levels of lactate, pyruvate, citrate and lowered glucose suggested increased fatty acid oxidation and glycolysis, while higher levels of free amino acids reflected muscle atrophy, breakdown of proteins and interconversions of amino acids to produce energy. These integrated system investigations demonstrate the potential of metabonomics for investigating the mechanistic basis of IBD, and it will provide novel avenues for management of IBD.

Bioactive food components, inflammatory targets, and cancer prevention

Various dietary components may modify chronic inflammatory processes at the stage of cytokine production, amplification of nuclear factor-kappaB-mediated inflammatory gene expression, and the release of anti-inflammatory cytokine, transforming growth factor-beta. This review provides a synopsis of the strengths and weaknesses of the evidence that specific bioactive food components influence inflammation-related targets linked to cancer. A target repeatedly surfacing as a site of action for several dietary components is transforming growth factor beta. Whereas the use of dietary intervention strategies offers intriguing possibilities for maintaining normal cell function by modifying a process that is essential for cancer development and progression, more information is needed to characterize the minimum quantity of the bioactive food components required to bring about a change in inflammation-mediated cancer, the ideal time for intervention, and the importance of genetics in determining the response. Unquestionably, the societal benefits of using foods and their components to prevent chronic inflammation and associated complications, including cancer, are enormous.

Insights into the roles of gut microbes in obesity

Obesity is a major public health issue as it enhances the risk of suffering several chronic diseases of increasing prevalence. Obesity results from an imbalance between energy intake and expenditure, associated with a chronic low-grade inflammation. Gut microbes are considered to contribute to body weight regulation and related disorders by influencing metabolic and immune host functions. The gut microbiota as a whole improves the host's ability to extract and store energy from the diet leading to body weight gain, while specific commensal microbes seem to exert beneficial effects on bile salt, lipoprotein, and cholesterol metabolism. The gut microbiota and some probiotics also regulate immune functions, protecting the host form infections and chronic inflammation. In contrast, dysbiosis and endotoxaemia may be inflammatory factors responsible for developing insulin resistance and body weight gain. In the light of the link between the gut microbiota, metabolism, and immunity, the use of dietary strategies to modulate microbiota composition is likely to be effective in controlling metabolic disorders. Although so far only a few preclinical and clinical trials have demonstrated the effects of specific gut microbes and prebiotics on biological markers of these disorders, the findings indicate that advances in this field could be of value in the struggle against obesity and its associated-metabolic disorders.

Sodium-dependent glucose transporter-1 as a novel immunological player in the intestinal mucosa

In this study, we demonstrate the protective effect of the activation of sodium-dependent glucose transporter-1 (SGLT-1) on damages induced by TLR ligands, in intestinal epithelial cells and in a murine model of septic shock. In intestinal epithelial cell lines, glucose inhibited the IL-8/keratinocyte-derived chemokine production and the activation of the TLR-related transcription factor NF-kappaB stimulated by LPS or CpG-oligodeoxynucleotide. Oral ingestion of glucose was found to protect 100% of mice from lethal endotoxic shock induced by i.p. LPS administration; protection was only observed when glucose was administered orally, not by i.p. route, suggesting the important role of intestinal epithelial cells in this protection. In addition, we observed that the in vivo protection depends on an increase of anti-inflammatory cytokine IL-10. The cornerstone of the observed immunomodulatory and life-saving effects resides in activation of SGLT-1; in fact, the glucose analog 3-O-methyl-d-gluco-pyranose, which induces the transporter activity, but is not metabolized, exerted the same inhibitory effects as glucose both in vitro and in vivo. Thus, we propose that activated SGLT-1, apart from its classical metabolic function, may be a promising target for inhibition of bacteria-induced inflammatory processes and life-saving treatments, assuming a novel role as an immunological player.

Nutrigenomics and gut health

Recognition of the interplay between genes and diet in development of disease and for maintenance of optimal metabolism has led to nutrigenomic or nutrigenetic approaches to personalising or individualising nutrition, with the potential of preventing, delaying, or reducing the symptoms of chronic diseases. Some of the development work has focussed on cardiovascular disease or type II diabetes mellitus, where various groups have identified potential diet-gene interactions. However, the available studies also emphasise the exponential increase in numbers of subjects necessary to recruit for clinical evaluation if we are to successfully provide informative high-dimensional datasets of genetic, nutrient, metabolomic (clinical), and other variables. There is also a significant bioinformatics challenge to analyze these. To add to the complexity, many of the pioneering studies had assumed that single nucleotide polymorphisms (SNPs) were the main source of human variability, but an increasing evidence base suggests the importance of more subtle gene regulatory mechanisms, including copy number variants. As an example, the risk of Inflammatory Bowel Disease (IBD) is associated with the inheritance of a number of contributory SNPs as well as with copy number variants of certain other genes. The variant forms of genes often result in disruptions to bacterial homeostasis mechanisms or to signal transduction of the intestinal epithelial cell of the host, and thereby to altered intestinal barrier function, and/or adaptive immune responses. The human gut microbiota is altered in individuals suffering from disorders such as IBD, and probiotic or prebiotic therapies or elemental diets may be beneficial to a high proportion of individuals through modifying the gut microbiota, and also modulating immune responses. New putative foods or dietary therapies may be identified through novel tissue culture screens, followed by further testing with in vivo animal models of human disease. A scientifically based rationale for developing novel foods related to genotype might use a combination of food fractionation, testing in tissue culture models and validation through animal models, before moving into human populations. However, the field of nutrigenomics raises ethical, legal and social issues, and will be of genuine benefit to human health only if developed in linkage with adequately trained health professionals. Such training will widen public understanding, and permit dialogue with regulatory officials to responsibly develop, apply and progress this new field.