Brush border and lysosomal marker enzyme profiles in duodenal mucosa from coeliac patients before and after organ culture

In VitroSystems for the Study of Cereal Proteins Toxic in Coeliac Disease

For a number of years, we have been carrying out investigations intended to clarify the nature of the toxic gliadin peptides, and whether different species and/or cultivars of wheat are tolerated to varying extents by people suffering from coeliac disease. Our investigations have been carried out using three main biological systems: 1) cultures of biopsy specimens of human intestinal mucosa; 2) cultures of rat fetal intestine; and 3) cultures of erythroid K562(S) cells.

Using these systems, we have tested several peptide mixtures prepared from gliadin and non-gliadin fractions extracted from wheats having various degrees of ploidy and from other cereals. Fraction preparation has been carried out by means of sequential digestion with pepsin and trypsin under experimental conditions simulating protein digestion in man. The results obtained indicate that the pathological symptoms associated with intolerance to gluten are largely due to the cytotoxic activity of wheat gliadin peptides toward immature enterocytes.

Dexamethasone-pDMAEMA polymeric conjugates reduce inflammatory biomarkers in human intestinal epithelial monolayers

The mucoadhesive polymer, poly(dimethylamino)ethyl methacrylate, (pDMAEMA), was synthesised by living radical polymerisation and subsequently conjugated by quaternisation reaction to a functionalised anti-inflammatory corticosteroid dexamethasone, to separately yield two conjugates with either 9:1 or 18:1 molar ratios of dexamethasone:polymer respectively. The hypothesis was to test whether the active agent maintained in vitro bioactivity when exposed to the apical side of human intestinal epithelial monolayers, Caco-2 and mucus-covered HT29-MTX-E12 (E12). HPLC analysis indicated high conjugate purity. Similar to pDMAEMA, fluorescently-labelled dexamethasone-pDMAEMA conjugates were bioadhesive to Caco-2 and mucoadhesive to E12. Apical addition of conjugates suppressed mRNA expression of the inflammatory markers, NURR1 and ICAM-1 in E12 following stimulation by PGE(2) and TNF-alpha, respectively. Conjugates also suppressed TNF-alpha stimulated cytokine secretion to the basolateral side of Caco-2 monolayers. Measurement of dexamethasone permeability from conjugates across monolayers suggested that conjugation reduced permeability compared to free dexamethasone. LDH assay indicated that conjugates were not cytotoxic to monolayers. Anti-inflammatory agents can therefore be successfully conjugated to polymers and they retain adhesion and bioactivity and have potential to be formulated for topical administration.

Barley and rye prolamins induce an mRNA interferon-gamma response in coeliac mucosa

BACKGROUND

In coeliac disease, wheat, barley and rye are traditionally excluded in the gluten-free diet. However, few studies have examined the small intestinal immune response to barley and rye.

AIM

To investigate the immunogenicity of barley and rye prolamins (hordein and secalin respectively) in comparison with wheat gliadin.

METHODS

Duodenal biopsies from 22 coeliac patients and 23 disease controls were cultured for 4 h with gliadin, hordein or secalin and compared with culture medium alone. Proinflammatory cytokines, interferon-gamma and interleukin-2, were quantified by TaqMan polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

Hordein caused the greatest increase in interferon-gamma mRNA in coeliac patients (median: 3.3-fold) in comparison with control subjects (median: 0.28-fold, P < 0.085). Secalin and gliadin induced similar levels of interferon-gamma mRNA with median fold-changes of 3.4 and 2.8, respectively, in coeliac patients in comparison with 1.6- and 1.1-fold increases in control subjects (P < 0.294 and P < 0.105, respectively). The median fold-changes for interleukin-2 mRNA did not differ between coeliac patients and controls. Cytokine protein was not upregulated.

CONCLUSION

The findings of this study provide evidence that barley and rye cause immune activation in the mucosa of coeliac patients and support the practice that barley and rye should be excluded from the gluten-free diet.

In vitro screening of food peptides toxic for coeliac and other gluten-sensitive patients: a review

Experience gained through investigations on coeliac disease makes it possible to propose a screening method based on agglutination of isolated K562(S) cells to evaluate the occurrence in food protein of amino acid sequences that are able to adversely affect coeliac and related gluten-sensitive patients. The method consists of in vitro sequential peptic and tryptic digestion of food protein fractions under optimal pH, temperature and time conditions and in vitro incubation of the digest with K562(S) cells; the toxic potential is detected as an agglutination of K 562 (S) cells after a short incubation. Other in vitro test systems, including atrophic coeliac intestinal mucosa and rat fetal intestine, can be used to confirm the results obtained with the isolated cells. A fractionation step of the proteolytic digest on a sepharose-mannan column before exposure of the in vitro systems to the separated peptide fractions adds to the sensitivity of the method. This screening method is not only very useful to investigate action mechanisms in coeliac disease, but also to assess the safety of genetically-modified plant foods and novel foods for gluten-sensitive patients.

Amines protect in vitro the celiac small intestine from the damaging activity of gliadin peptides

Proteins and peptides responsible for the celiac small intestinal lesion inhibit both the enterocyte recovery of in vitro cultured flat celiac mucosa and the in vitro development of fetal rat intestine. They also agglutinate K 562 (S) cells. Using these three in vitro systems (cultured human celiac and rat fetal intestine and cell agglutination), it is shown that several small-molecular-weight amines, mostly the polyamines spermidine and spermine, prevent and reverse K 562 (S) cell agglutination induced by gliadin peptides, whereas they do not prevent cell agglutination induced by concanavalin A and wheat germ agglutinin. Some of these amines also protected in vitro developing fetal rat intestine and flat celiac mucosa from the damaging effect of gliadin peptides. This protective effect may be related to the trophic activity exerted by amines on the intestine and/or the effect of amines on the functions of intestinal brush border or intracellular membranes involved in the intestinal handling of gliadins.

Gluten-sensitive enteropathy in childhood

Genetic and environmental factors (breast feeding, probably viral infections) play a role in the expression of the disease. Prevalence of GSE in childhood did not substantially decrease in the last 15 years in all European countries, where GSE is still more common in infantile age and presents frequently gastrointestinal symptoms. A decrease has been reported in childhood in several United Kingdom areas and in Finland, where the clinical presentation is changing, shifting upward with age and coming closer to the adult type of the disease. The following clinical problems have been reported in the recent literature: enamel hypoplasia; monosymptomatic short stature; arthritis and other immunologic diseases; association with diabetes, atopy, Iga deficiency, and probably Down's syndrome. Delay in puberty and other peculiar problems of the disease have been described in adolescents. Tests assessing the permeability of the small intestine and the blood levels of antigliadin antibodies have recently gained success as noninvasive tools for the diagnosis of the GSE. The gluten should be withdrawn from the diet and the challenge with gluten should be performed not before 12 months of gluten-free diet with an accurate timing of the biopsy on the basis of the antigliadin and antireticulin antibodies, to avoid clinical and growth damage. Celiac children do require a permanent gluten-free (and not poor) diet. In reality, too many celiac adolescents are off-diet.

Organ culture of gastrointestinal mucosa--a technique for the study of the human gastrointestinal tract

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