Intestinal epithelial function: the case for immunophysiological regulation. Implications for disease (2)

A proof of principle study investigating the effects of supplemental concentrated brewer's yeast on markers of gut permeability, inflammation, and fecal metabolites in healthy non-challenged adult sled dogs

Yeast-derived β-glucans impact immunity, though their effects on gut permeability and inflammation are less understood. Most research has investigated other components of the yeast cell wall, such as the prebiotic mannan- and fructo-oligosaccharides. The objective of this study was to assess the effects of feeding a concentrated yeast product on markers of inflammation (serum amyloid A [SAA] and haptoglobin [Hp]) and oxidative status (malondialdehyde [MDA]), fecal products of fermentation, and gut permeability. Nineteen privately owned domestic Siberian huskies, and one Alaskan husky (9 females: 5 intact, 4 spayed; 11 males: 3 intact, 8 neutered), with an average age of 4.8 ± 2.6 yr and body weight (BW) of 25.6 ± 4.1 kg, were used in this study. Dogs were blocked and randomly allocated to one of two diet groups. Ten dogs received a dry extruded diet. The other 10 received the same diet top dressed with yeast for a daily β-glucan dose of 7 mg/kg BW for 10 wk. Fecal collection, for evaluation of fecal metabolites, and scoring occurred weekly. Gut permeability was assessed using the chromium-labeled ethylenediamine tetra-acetic acid (Cr-EDTA) and iohexol markers prior to the initiation of dietary treatment and after 10 wk of treatment. Blood samples were collected premarker administration and 0.5, 1, 2, 3, 4, 5, and 6 h postadministration. Fasting concentrations of SAA, Hp, and MDA were measured on weeks -1, 2, 4, and 8. Incremental area under the curve (I-AUC) was calculated for serum iohexol and Cr-EDTA concentrations. All data were analyzed using PROC GLIMMIX of SAS with dog as random effect, and week as fixed effect and repeated measure. Dogs receiving treatment tended to have decreased I-AUC of Iohexol (P = 0.10) and Cr-EDTA (P = 0.06) between baseline and cessation of treatment compared to the change over time in I-AUC for control (Ctl) dogs. Treatment dogs had lower Hp concentrations (P ≤ 0.05) than Ctl. There were no differences between treatments for SAA and MDA concentrations (P > 0.05). Fecal arabinose concentrations were greater in treatment (Trt) dogs (P ≤ 0.05) compared to Ctl, though no other fecal metabolites were affected by treatment. There was no difference in the relative frequency of defecations scored at any fecal score between Trt and Ctl dogs, and mean score did not differ between groups (P > 0.10). These data suggest that concentrated brewer's yeast may have the potential to reduce gut permeability without impacting inflammatory status and markers of health in adult dogs.

Lipopolysaccharides modulate intestinal epithelial permeability and inflammation in a species-specific manner

Patients presenting with Inflammatory bowel disease have been shown to exhibit an altered microbiome in both Crohn's disease and Ulcerative colitis. This shift in the microbial content led us to question whether several of these microbes are important in inflammatory processes present in these diseases and more specifically whether lipopolysaccharides from the gram-negative cell wall differentially stimulates resident cells. We, therefore, investigated the possible contribution of five major species of gram-negative bacteria found to be altered in presence during disease progression and evaluate their pathogenicity through LPS. We demonstrated that LPS from these different species had individual capacities to induce NF-κB and pro-inflammatory IL-8 production from HEK-TLR4 cells in a TLR4 dependent manner. Additional work using human intestinal colonic epithelial cell monolayers (Caco-2) demonstrated that the cells responded to the serotype specific LPS in a distinct manner, inducing many inflammatory mediators such as TNF-α and IL-10 in significantly altered proportions. Furthermore, the permeability of Caco-2 monolayers, as a test for their ability to alter intestinal permeability, was also differentially altered by the serotype specific LPS modulating trans-epithelial electrical resistance, small molecule movement, and tight junction integrity. Our results suggest that specific species of bacteria may be potentiating the pathogenesis of IBD and chronic inflammatory diseases through their serotype specific LPS responses.

Deciphering the pathophysiology of irritable bowel syndrome and functional gastrointestinal disorders-an alternative model for pathogenesis: cytokine controlled transepithelial multi-feedback loop

A working theoretical model for irritable bowel syndrome (IBS) and other functional gastrointestinal disorders (FGIDs) does not exist, hampered by the lack of any clear cut invention that address all symptom and signs of the disease. Reports of cessation of symptom and signs of both major types of IBS have been published using a non-systemic, topically active agent-high potency polymerized cross-linked sucralfate (HPPCLS). The unique clinical effect of this non-systemic agent restricted to the luminal surface of the gut provides opportunity to elaborate on an alternative working model for the pathogenesis of IBS and FGIDs. While the chemical determinants of HPPCLS and the mucosal lining contribute to the clinical effects, the sequence of events resides in the functional interplay among elements within the mucosa itself. The proposed model assumes that failure of a pre-existing genomic-controlled surveillance of the epithelium localized to the luminal surface triggers primary and secondary immune activation of inflammation intent on restoring epithelial homeostasis. Delayed restoration of homeostasis results in all the symptoms, signs and likely molecular events that characterize IBS and FGIDs.

High-potency sucralfate prevents and rapidly reverses chemo-radiation mucositis in a patient with stage 4b head and neck cancer

AIM: To study usefulness of high-potency sucralfate (HPS) in a patient with chemoradiation mucositis and discuss its mechanism of action.

METHODS: HPS, a non-covalently cross-link of sucralfate, cations and bidentate anionic chelators, has a maintains a surface concentration of sucralfate 3 h following administration that is 7-23 fold that possible with standard-potency sucralfate. The accelerated mucosal healing and pain alleviation of HPS in patients with erosive esophageal reflux, prompted its use in this patient with chemoradiation mucositis of the oropharynx and alimentary tract. A literature-based review of the immuno-modulatory effects of sucralfate is discussed.

RESULTS: Within 48 h of intervention: (1) there was complete disappearance of oral mucositis lesions; tenderness with (2) patient-reported disappearance of pain, nausea and diarrhea; patient required (3) no opiate analgesia and (4) no tube-feeding supplements to regular diet. Dysgeusia and xerostomia persisted. A modified Naranjo Questionnaire score of 10 supported the likelihood that HPS intervention caused the observed clinical effects. No adverse reactions noted.

CONCLUSION: In this patient HPS was useful to treat chemo-radiation mucositis of the oropharynx and alimentary tract. HPS may directly or indirectly facilitate an immunomodulatory mechanism involving accelerated growth factor activation, which may be a new target for therapeutic intervention in such patients.

Nonruminant Nutrition Symposium: Neurogastroenterology and food allergies

Neurogastroenterology is a subspecialty encompassing relations of the nervous system to the gastrointestinal tract. The central concept is emergence of whole organ behavior from coordinated activity of the musculature, mucosal epithelium, and blood vasculature. Behavior of each effector is determined by the enteric nervous system (ENS). The ENS is a minibrain positioned close to the effectors it controls. The ENS neurophysiology is in the framework of neurogastroenterology. The digestive tract is recognized as the largest lymphoid organ in the body with a unique complement of mast cells. In its position at the "dirtiest" of interfaces between the body and outside world, the mucosal immune system encounters food antigens, bacteria, parasites, viruses, and toxins. Epithelial barriers are insufficient to exclude fully the antigenic load, thereby allowing chronic challenges to the immune system. Observations in antigen-sensitized animals document direct communication between the mucosal immune system and ENS. Communication is functional and results in adaptive responses to circumstances within the lumen that are threatening to the functional integrity of the whole animal. Communication is paracrine and incorporates specialized sensing functions of mast cells for specific antigens together with the capacity of the ENS for intelligent interpretation of the signals. Immuno-neural integration progresses sequentially, beginning with immune detection, followed by signal transfer to the ENS, followed by neural interpretation and then selection of a neural program with coordinated mucosal secretion and a propulsive motor event that quickly clears the threat from the intestinal lumen. Operation of the defense program evokes symptoms of cramping abdominal pain, fecal urgency, and acute watery diarrhea. Investigative approaches to immuno-ENS interactions merge the disciplines of mucosal immunology and ENS neurophysiology into the realm of neurogastroenterology.

Dietary soya saponins increase gut permeability and play a key role in the onset of soyabean-induced enteritis in Atlantic salmon ( Salmo salar L.)

Saponins are naturally occurring amphiphilic molecules and have been associated with many biological activities. The aim of the present study was to investigate whether soya saponins trigger the onset of soyabean-induced enteritis in Atlantic salmon (Salmo salar L.), and to examine if dietary soya saponins increase the epithelial permeability of the distal intestine in Atlantic salmon. Seven experimental diets containing different levels of soya saponins were fed to seawater-adapted Atlantic salmon for 53 d. The diets included a fishmeal-based control diet, two fishmeal-based diets with different levels of added soya saponins, one diet containing 25% lupin kernel meal, two diets based on 25% lupin kernel meal with different levels of added soya saponins, and one diet containing 25% defatted soyabean meal. The effect on intestinal morphology, intestinal epithelial permeability and faecal DM content was examined. Fish fed 25% defatted soyabean meal displayed severe enteritis, whereas fish fed 25% lupin kernel meal had normal intestinal morphology. The combination of soya saponins and fishmeal did not induce morphological changes but fish fed soya saponins in combination with lupin kernel meal displayed significant enteritis. Increased epithelial permeability was observed in fish fed 25% defatted soyabean meal and in fish fed soya saponin concentrate independent of the protein source in the feed. The study demonstrates that soya saponins, in combination with one or several unidentified components present in legumes, induce an inflammatory reaction in the distal intestine of Atlantic salmon. Soya saponins increase the intestinal epithelial permeability but do not, per se, induce enteritis.

Effects of bacteria on the enteric nervous system: implications for the irritable bowel syndrome

A unified scenario emerges when it is considered that a major impact of stress on the intestinal tract is reflected by symptoms reminiscent of the diarrhea-predominant form of irritable bowel syndrome. Cramping abdominal pain, fecal urgency, and explosive watery diarrhea are hallmarks not only of diarrhea-predominant irritable bowel syndrome, but also of infectious enteritis, radiation-induced enteritis, and food allergy. The scenario starts with stress-induced compromise of the intestinal mucosal barrier and continues with microorganisms or other sensitizing agents crossing the barrier and being intercepted by enteric mast cells. Mast cells signal the presence of the agent to the enteric nervous system (ie, the brain-in-the-gut), which uses one of the specialized programs from its library of programs to remove the "threat." This is accomplished by stimulating mucosal secretion, which flushes the threatening agent into the lumen and maintains it in suspension. The secretory response then becomes linked to powerful propulsive motility, which propels the secretions together with the offending agent rapidly in the anal direction. Cramping abdominal pain accompanies the strong propulsive contractions. Urgency is experienced when arrival of the large bolus of liquid distends the recto-sigmoid region and reflexly opens the internal anal sphincter, with continence protection now provided only by central reflexes that contract the puborectalis and external anal sphincter muscles. Sensory information arriving in the brain from receptors in the rapidly distending recto-sigmoid accounts for the conscious sensation of urgency and might exacerbate the individual's emotional stress. The symptom of explosive watery diarrhea becomes self-explanatory in this scenario.

Regulation of intestinal epithelial gene expression in hypoxia

Mucosal hypoxia is intimately associated with chronic inflammation in the gastrointestinal tract in disease such as Crohn's disease. Under such conditions, intestinal epithelial cells may become a source of proinflammatory cytokines, including tumor necrosis factor alpha (TNFalpha), which actively contribute to ongoing inflammation through autocrine disruption of epithelial barrier function. These events are critically dependent upon alterations in the expression and function of the cAMF response element binding protein (CREB). Here we review our understanding of the molecular mechanisms underlying the regulation of CREB activity in intestinal epithelial cells in hypoxia.

Enteric neuroimmunophysiology and pathophysiology

Minute-to-minute behavior of the bowel, whether it is normal or disordered, is determined by integrative functions of the enteric nervous system (ENS). Information input processed by the ENS is derived from local sensory receptors, the central nervous system, and immune/inflammatory cells including mast cells. Enteric mast cells use the power of the immune system for detection of antigenic threats and for long-term memory of the identity of the specific antigens. Specific antibodies attach to the mast cells and enable the mast cell to detect sensitizing antigens when they reappear in the gut lumen. Should the sensitizing antigen reappear, mast cells detect it and signal its presence to the ENS. The ENS interprets the mast cell signal as a threat and calls up from its program library secretory and propulsive motor behavior that is organized to eliminate the threat rapidly and effectively. Operation of the alarm program protects the individual, but at the expense of symptoms that include cramping abdominal pain, fecal urgency, and diarrhea. Enteric mast cells use immunologic memory functions to detect foreign antigens as they appear and reappear throughout the life of the individual. Mast cells use paracrine signaling for the transfer of chemical information to the neural networks of the ENS. Integrative circuits in the ENS receive and interpret the chemical signals from the mast cells. Signals from the mast cells are interpreted by the ENS as a labeled code for the presence of a threat in the intestinal lumen.

Chloride secretion by the intestinal epithelium: molecular basis and regulatory aspects

Chloride secretion is the major determinant of mucosal hydration throughout the gastrointestinal tract, and chloride transport is also pivotal in the regulation of fluid secretion by organs that drain into the intestine. Moreover, there are pathological consequences if chloride secretion is either reduced or increased such as in cystic fibrosis and secretory diarrhea, respectively. With the molecular cloning of many of the proteins and regulatory factors that make up the chloride secretory mechanism, there have been significant advances in our understanding of this process at the cellular level. Similarly, emerging data have clarified the intercellular relationships that govern the extent of chloride secretion. The goal of our article is to review this area of investigation, with an emphasis on recent developments and their implications for the physiology and pathophysiology of chloride transport.

Muscarinic inhibition of substance P induced ion secretion in piglet jejunum

We examined the effects of the muscarinic agonist carbachol on ion secretion induced by substance P (SP) in piglet jejunal tissues mounted in Ussing chambers. Tetrodotoxin was present in all solutions to inhibit neural activity. Carbachol added 10 min prior to 0.75 µM SP dose dependently inhibited subsequent SP responses, with 90% inhibition at 10 µM carbachol. Addition of an equipotent dose of SP (7.5 µM) had no effect on subsequent carbachol-induced secretion. Carbachol's inhibition of SP-induced secretion was evident for at least 45 min and was abolished by prior addition of the M3 receptor antagonist 4-diphenylacetoxy-N-methyl-piperidine methiodide (4-DAMP), but remained intact in the presence of the M2 antagonist gallamine or the nicotinic antagonist mecamylamine. Atropine added 10 min after carbachol restored subsequent SP responses toward control levels. Carbachol also reduced secretory responses to histamine and, to a lesser extent, prostaglandin E2 (PGE2). SP-induced secretion was not affected by prior addition of histamine and was reduced by PGE2 only at the highest PGE2 concentration. The results suggest that activation of the epithelial M3 receptor by carbachol inhibits subsequent secretory responses to the calcium-mediated agonists SP and histamine in piglet jejunum. This may reflect muscarinic activation of a negative messenger in epithelial cells that limits Cl- secretion.Key words: substance P, muscarinic receptor, carbachol, desensitization, piglet, jejunum, intestine, ion secretion.

Tyrosine kinase and MAPK inhibition of TNF-alpha- and EGF-stimulated IEC-6 cell growth

The role of TNF-alpha in modulating intestinal crypt cell growth was examined, in comparison with EGF. Both significantly increased IEC-6 cell proliferation. Neither EGF nor TNF-alpha overcame the inhibitory effect on growth exerted by the tyrosine kinase inhibitor genistein. Immunoblots with phosphotyrosine antibodies showed increased tyrosine phosphorylation of IEC-6 cell proteins in response to EGF and TNF-alpha stimulation. TNF-alpha increased ERK1 and ERK2 MAPK phosphorylation. A MAPK assay confirmed the increased activity upon TNF-alpha stimulation. Selective inhibition of MAPK activation by PD98059 resulted in a dose dependent inhibition of TNF-alpha or EGF-induced IEC-6 cell growth. These findings suggest a role for TNF-alpha in the regulation of intestinal epithelial cell growth and that the mitogenic effect of TNF-alpha requires protein tyrosine phosphorylation and MAPK activation.

Review article: In vitro models in inflammatory bowel disease research--a critical review

Research efforts in inflammatory bowel disease (IBD) have been directed towards the epithelium as it has become clear that epithelial cells play a critical role in inflammatory response. Most research involving IBD employs in vitro techniques. In vitro epithelial cell studies have played and are continuing to play a major role in providing specific information relevant to IBD. Thus, such studies have provided irrefutable evidence that epithelial responses can be induced by microbes/microbial products and by immune activation. Culture experiments have provided insights into the effects of individual cytokines and other inflammatory mediators on epithelial pathophysiology, injury and repair, apoptosis, necrosis, and other processes that may be involved in IBD. Activated epithelial cells can participate in and even orchestrate immune responses, by stimulating T cells (and possibly others) and by producing cytokines that recruit specific inflammatory cells. Physiological regulation of epithelial tight junctions has been demonstrated by in vitro studies; the implication of this information for treating IBD is just beginning to be explored. It is becoming increasingly clear that epithelial processing and presentation of antigens is critical to the outcome of the immune response.

The intestinal epithelial cell: immunological aspects

IECs likely play an important role in immunological defense mechanism. Apart from being a passive barrier against luminal bacteria, IECs secrete protective and microbiocidal products such as ITF, complement components and cryptdins into the lumen. Moreover, IECs produce secretory component that is essential for the transport of IgA from the lamina propria into the lumen. IECs also have regulatory functions. They express adhesion molecules important in the homing of T cells and other leukocytes, and likely modulate T cell functions in a paracrine way. Furthermore, IECs secrete cytokines, either constitutively or after bacterial challenge, and they express cytokine receptors. Lastly, IECs may play an important role as non-professional antigen-presenting cells by expressing classical MHC class I and class II and nonclassical MHC class I molecules on the cell surface. This aspect is particularly intriguing in that IECs also express a FcR that may have a function in luminal antigen sampling.

Interleukin-8 production by the human colon epithelial cell line HT-29: modulation by interleukin-13

1. We have determined which cytokines induce and modulate the production of the chemokine interleukin-8 (IL-8) by the human colonic epithelial cell line HT-29. 2. Growth arrested cell cultures were stimulated with the human recombinant cytokines interleukin-1 alpha (IL-1 alpha), tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-13 (IL-13), interleukin-10 (IL-10) or vehicle added alone or in combination. The production of IL-8 was determined by enzyme-linked immunosorbent assay (ELISA) and IL-8 messenger RNA expression by Northern blot analysis. 3. The production of IL-8 in unstimulated cells was undetectable by both ELISA and Northern blot analysis. 4. HT-29 cells produced IL-8 following stimulation with IL-1 alpha or TNF-alpha in a time- and a concentration-dependent manner, while IFN-gamma, IL-10 and IL-13 did not induce IL-8 production by HT-29 cells. 5. IL-13 was found to up-regulate significantly (P < 0.01) the IL-1 alpha but not the TNF-alpha-induced IL-8 generation by HT-29 cells. In contrast, IL-10 had no effect on either IL-1 alpha or TNF-alpha-induced IL-8 production. 6. Experiments using cycloheximide demonstrated that this synergistic effect of IL-13 and IL-1 alpha on IL-8 secretion was not through de novo protein synthesis. Using actinomycin-D, we demonstrated that the IL-13 up-regulation was at the level of transcription rather than messenger RNA stability. 7. These findings suggest that colonic epithelial cells have a functional IL-13 receptor, which is coupled to an up-regulation of IL-1 alpha, but not TNF-alpha induced IL-8 generation.

Inducible nitric oxide synthase activity and expression in a human colonic epithelial cell line, HT-29

1 We have determined which cytokines regulate the expression of human inducible nitric oxide synthase (iNOS) mRNA and nitrite generation in the human colonic-epithelial cell line HT-29. 2 Growth arrested cell cultures were stimulated with the human recombinant cytokines interleukin-1 alpha (IL-1 alpha), tumour necrosisfactor-alpha (TNF-alpha), interferon gamma (IFN-gamma) or vehicle added alone or in combination. Human iNOS mRNA was determined by Northern blot analysis and nitrite generation by the use of a fluorometric assay. 3 Unstimulated cells produced a small time-dependent increase in nitrite generation of 50 +/- 4, 75 +/- 8, and 103 +/- 8 nM per 10(6) cells at 24 h, 48 h, and 72 h respectively. This nitrite generation was unaffected by cycloheximide (5 micrograms ml-1) pretreatment and iNOS mRNA was not detected. 4 None of cytokines alone induced either iNOS mRNA expression or an increase in nitrite generation. The combination of IL-1 alpha/IFN-gamma produced a highly significant (P < 0.001) 4 fold increase in nitrite production at 48 h, compared to basal values, while no other pair of cytokines was effective. 5 Time course studies with IL-1 alpha/IFN-gamma combination revealed significant (P < 0.001) increases in nitrite at 24 h (153 +/- 7), 48 h (306 +/- 24), and 72 h (384 +/- 15) compared to basal values of 50 +/- 4, 75 +/- 8, and 103 +/- 8 nM per 10(6) cells respectively. 6 Studies with IL-1 alpha/IFN-gamma combination demonstrated a time dependent expression of iNOS mRNA, first observed at 6 h, peaked at 24 h and was undetectable by 72 h. IL-1 alpha (0.3-10 ng ml-1) and IFN-gamma (10-300 u ml-1) in combination induced a concentration-dependent expression of iNOS mRNA at 24 h. 7 Pretreatment with cycloheximide before IL-1 alpha/IFN-gamma stimulation reduced nitrite levels to basal values. These data suggest that the IL-1 alpha/IFN-gamma-induced nitrite production by HT-29 cells is dependent on de novo protein synthesis, probably the iNOS enzyme. 8 The addition of TNF-alpha produced a significant (P < 0.001) 3 fold increase of IL-1 alpha/IFN-gamma-induced nitrite generation. In marked contrast the presence of TNF-alpha had no effect on IL-1 alpha/IFN-gamma-induced iNOS mRNA expression by HT-29 cells. These findings suggest that the up-regulation by TNF-alpha of IL-1 alpha/IFN-gamma-induced nitrite generation is at the post-transcriptional level. 9 These data suggest that pro-inflammatory cytokines induce NO production in colonic epithelial cells probably due to the induction of iNOS and these cells may be a major source of NO generation in inflammatory bowel disease.

Milk proteins, cytokines and intestinal epithelial functions in children

This paper discusses the relationship between food antigens, lymphocytes and the epithelial properties of the jejunum in children with cow's milk allergy. Experimental results indicate that increased protein permeability is not the primary cause of cow's milk allergy. Rather, results are interpreted as a secondary effect of an abnormal immunological response leading to mucosal inflammation and impairment of the endocytic process by the intestinal epithelial cells. Stimulation by cow's milk proteins caused the lymphocytes from infants with cow's milk allergy to release more tumor necrosis factor-alpha TNF alpha than those from control infants. After appropriate antigenic stimulation, the cytokines released by the activated lymphocytes from these infants perturbed epithelial function, in particular its barrier capacity. Tumor necrosis factor alpha, together with gamma interferon are involved in these adverse effects. It is thought that bovine beta-lactoglobulin present in the intestinal lumen may be responsible for the secretory diarrhea observed in children with cow's milk allergy, as a consequence of stimulation of electrogenic chloride secretion. In addition, luminal foreign protein may stimulate the submucosal cells. As a consequence, the submucosal release of mediators, including lymphokines, might alter the intestinal epithelial barrier. In conclusion, in physiological conditions, the subepithelial tissue that comprises the immune system and many other systemic systems receive information on the antigenic content within the intestinal lumen via the intestinal epithelium.

Regulation of chloride secretion in mammalian colon

A number of procedures or interventions which activate electrogenic ion transport in mammalian intestine are reviewed. Using in vitro models it is possible to demonstrate direct or indirect pathways to stimulate chloride secretion. Such activation, in vivo, would change the gut from a state of net water absorption to one of fluid secretion. The movement of water is driven by electrical and osmotic gradients set up as a consequence of opening regulated ion channels in epithelial cells. Secretagogues may govern epithelial intracellular second messenger pathways to regulate ion channel activity directly or by activation of membrane bound receptors on the surface of epithelial cells. In health or disease secretagogues may be derived from cells within the attendant lamina propria of the intestinal mucosa. Pharmacological techniques may be employed to determine which mediators contribute to indirect stimulation of electrogenic ion transport by activation of neurons or of immunocytes (mast cells or phagocytes). Dissection and reconstruction of models of intestinal hypersensitivity reactions show that neuro-immune networks which regulate intestinal ion transport appear to be complex, functionally integrated systems. Analysis of such interactions may identify cellular or humoral targets with which to examine novel diagnostic, preventative or therapeutic strategies with regard to intestinal diseases.