Thermal treatment reduces gliadin recognition by IgE, but a subsequent digestion and epithelial crossing permits recovery.

Wheat is one of the most important crops in the world in terms of human nutrition. With regards to health, some individuals exhibit wheat-related disorders such as food allergy to wheat (FAW). In this disorder, gluten is involved, particularly the gliadins which are among the main proteins responsible for FAW. Food processing, as well as digestibility and intestinal transport are key factors to consider since they may affect the allergenic potential of food allergens. Wheat is always consumed after heat processing and this step may impact epitope accessibility by inducing aggregation and may irreversibly destroy conformational epitopes. Our aim was to investigate the effects of heating and digestion on the structure of well-known allergens (total gliadins and α-gliadins) and their capacity to maintain their allergenic potential after crossing an intestinal barrier. The sizes of the processed (heated and heated/digested) proteins were characterized by laser light scattering and chromatographic reverse phase. The IgE-binding capacities of native and processed proteins were checked using a dot blot with sera from wheat allergenic patients. Furthermore, the abilities of these samples to cross the intestinal barrier and to induce mast cell degranulation were investigated by combining two in vitro cellular models, Caco-2 and RBL-SX38. The heat treatment of total gliadins and α-gliadins induced the production of large aggregates that were hardly recognized by IgE of patients in dot-blot. However, after limited pepsin hydrolysis, the epitopes were unmasked, and they were able to bind IgE again. Native proteins (gliadins and α-type) and processed forms were able to cross the Caco-2 cells in small amount. Permeability studies revealed the capacity of α-gliadins to increase paracellular permeability. In the RBL assay, the total native gliadins were able to trigger cell degranulation, but none of their processed forms. However after crossing the CaCo-2 monolayer, processed gliadins recovered their degranulation capacity to a certain extent. Total native gliadins remained the best allergenic form compared to α-type.

Heterologous expression and purification of native and mutated low molecular mass glutenin subunits from durum wheat.

Wheat technological properties are correlated with the size of glutenin polymers, consisting of high and low molecular mass glutenin subunits, linked together by disulphide bonds. In order to unravel glutenin polymer structure, we considered three LMW-GS genes, which differ in the number of cysteine residues and in the repetitive domain length. The three LMW-GS genes have been expressed in Escherichia coli, and purified with a yield of 40-100 mg/l of culture volume, depending on protein type. Single polypeptides are being used in re-oxidation and micro-mixographic experiments, in order to detect the influence of the differential structural characteristics on glutenin polymer formation.

Effects of 50 Hz sinusoidal electromagnetic fields on MCP-1 and RANTES generated from activated human macrophages.

Extremely low frequency electromagnetic fields (ELF-EMF) induce cellular changes and modulate signal transduction pathways, and may be beneficial in the treatment of inflammatory diseases. In this paper we studied two inflammatory chemokines, MCP-1 and RANTES produced by human cultured isolated monocytes from peripheral blood, with or without PHA and in the absence or presence of 50 Hz magnetic field of 1.0 mT for 24 h. The production of MCP-1 and RANTES was determined by ELISA method. Here, we found that ELF-EMF strongly inhibited the production of these chemokines stimulated by PHA, while the control was not affected. Since MCP-1 and RANTES exert chemoattraction for several populations inflammatory leukocytes, the inhibitory effect of these chemokines could be one of the mechanisms by which ELF-EMF is therapeutic in inflammatory diseases.

Lymphocyte subset changes in blood and gastrointestinal mucosa after oral nickel challenge in nickel-sensitized women.

This study investigates lymphocyte subsets in both the gastrointestinal mucosa and blood, in patients with nickel allergic contact dermatitis, after 10 mg oral nickel challenge (double-blind, placebo-controlled). 6 such patients with cutaneous symptoms induced only by skin contact with nickel (group A), 6 with a flare-up of cutaneous symptoms after food nickel ingestion (group B) and 6 healthy controls (group C) were enrolled. Blood lymphocyte subsets (CD4, CD45RO, CD8) were analyzed before and after 4 and 24 h from the challenge (test 1, 2, and 3), and intestinal biopsies were performed 2 days later. Challenges were positive in group B and negative in group A and controls. Serum and urine nickel levels significantly increased after nickel ingestion, with no differences between the 3 groups. At test 3, a significant decrease of the all CDs studied was found in group B. Biopsies of this group showed higher levels of CD45RO+ cells in the lamina propria and in the epithelium and lower levels of epithelial CD8+ lymphocytes. This study confirms that ingested nickel may induce flare-up of cutaneous reactions in some nickel-allergic patients, independently of the degree of sensitization and the intake of metal. In these patients, oral nickel stimulates the immune system, inducing maturation of T lymphocytes from virgin into memory cells; these latter cells seem to accumulate in the intestinal mucosa. The immunoreaction also involves CD8+ cells, whose role is not yet clear.

Characterization of a low-molecular-weight glutenin subunit gene from bread wheat and the corresponding protein that represents a major subunit of the glutenin polymer.

Both high- and low-molecular-weight glutenin subunits (LMW-GS) play the major role in determining the viscoelastic properties of wheat (Triticum aestivum L.) flour. To date there has been no clear correspondence between the amino acid sequences of LMW-GS derived from DNA sequencing and those of actual LMW-GS present in the endosperm. We have characterized a particular LMW-GS from hexaploid bread wheat, a major component of the glutenin polymer, which we call the 42K LMW-GS, and have isolated and sequenced the putative corresponding gene. Extensive amino acid sequences obtained directly for this 42K LMW-GS indicate correspondence between this protein and the putative corresponding gene. This subunit did not show a cysteine (Cys) at position 5, in contrast to what has frequently been reported for nucleotide-based sequences of LMW-GS. This Cys has been replaced by one occurring in the repeated-sequence domain, leaving the total number of Cys residues in the molecule the same as in various other LMW-GS. On the basis of the deduced amino acid sequence and literature-based assignment of disulfide linkages, a computer-generated molecular model of the 42K subunit was constructed.

Serum and urine nickel in nickel-sensitized women: effects of oral challenge with the metal.

15 women with a positive patch test only to nickel (Ni) and without atopy and 10 control women were selected for the study. Blood and urine specimens were collected with a standard procedure either before (at 8 a.m.) or 4 and 24 h after the ingestion of 10 mg of Ni (as Ni sulfate). 7 of the Ni-sensitized patients showed a flare-up of eczema and/or urticaria during the test, while the other women were non-symptomatic. Serum and urine Ni of controls and Ni-sensitized women did not significantly differ. Serum and urine Ni levels determined before the oral Ni challenge were in the range of reference values recently reported by other authors (0.2-2.0 micrograms/l of serum or urine). Ni was greatly augmented in urine and serum 4 h after the challenge (25th-75th percentiles: 43-264 micrograms/l urine Ni and 15-52 micrograms/l serum Ni). 24 h after Ni ingestion, urine Ni was 41-153 micrograms/l and serum Ni 4-17 micrograms/l. Our study confirms a previous investigation showing similar levels of serum and urine Ni following ingestion of the metal in control and Ni-sensitized women without atopy.

[Allergic contact dermatitis to nickel: modification of receptor expression on peripheral lymphocytes of women after oral provocation tests (preliminary data)]. / Dermatite allergica da contatto a nichel: modificazioni delle espressioni recettoriali dei linfociti periferici in donne dopo test di provocazione per via orale (dati preliminari)

Blood lymphocyte subset evaluation was performed before after oral challenge with 10 mg of Ni, in 9 healthy women and in 15 allergic to Ni. Following challenge, 7 allergic showed a flare up of eczema and/or urticaria. In the controls, CD4+ lymphocytes were modified 24 hours after Ni challenge: CD4+/CD44RO- "virgin" cells were reduced while CD4+/CD45RO+ "memory" cells increased. The allergic women, not sensitive to oral Ni, showed an increase of B lymphocytes after the test. On the contrary, the oral Ni reacting patients presented a reduction of monocytes 4 hours after Ni ingestion and marked reduction (ranging from 20 to 50%) of T and B lymphocytes after 24 hours. These significant T and B lymphocytes changes suggest a migration of the cells in peripheral tissues, likely skin and GUT mucosa.

[Immuno-histopathologic changes in the gastrointestinal mucosa in patients with nickel contact allergy]. / Modificazioni immuno-istopatologiche della mucosa gastro-intestinale in pazienti con allergia da contatto al Nichel.

The study concerns the histological and immunohistochemical findings of the gastrointestinal mucosa of 20 patients (group A) suffering from contact allergic dermatitis (CAD) to Ni, with symptom recrudescence due to food ingested Ni. Results were compared with those observed in 20 patients suffering from CAD to Ni (group B), without sensitivity to food ingested Ni, and in 20 normal subjects (controls). The sensitivity to food ingested Ni, as suggested by history, was demonstrated by placebo-controlled oral-Ni challenge. The biopsies for histological and immunohistochemical study were performed during endoscopy and obtained from the antrum and from the duodenal mucosa. In the biopsies obtained from 16 of group A patients there was evidence of inflammatory infiltrate of lymphocytes and plasma cells with oedema and vasodilation in the lamina propria. Slight flattening of the villi and enlongation of the crypts were concomitant. These findings were light in the 4 patients of group A and in 11 of group B and instead were absent in the remaining group B patients and in the controls. Immunohistochemically, lymphocytes in the lamina propria were prevalently CD20 + (B cells) and CD4 + (Th cells), some were CD45RO + (memory) and finally few CD8 + (Tc/s cells). CD45RO + cells was found in cluster in patients of group A and in 4 of group B, whereas in the others were isolated. Since some studies have shown that immunological pattern of skin reaction to Ni is characterized by increased CD45RO + cells, it may be hypothesized that in patients suffering from CAD to Ni, the sensitivity to food-ingested Ni may be induced by a type IV immunological reaction in the gut.

Development of a set of oligonucleotide primers specific for genes at the Glu-1 complex loci of wheat.

Specific amplification of the complete coding region of all six high-molecular-weight (HMW) glutenin genes present in hexaploid wheat was obtained by the polyerase chain reaction (PCR). Primers specific for the N-terminal region of the 1Dx gene and for the repetitive domain of the y-type HMW glutenin genes were also developed. Although the primers were constructed on the basis of the nucleotide sequences of HMW glutenin genes present in T. aestivum L. cv 'Cheyenne', they were very efficient in amplifying HMW glutenin genes of diploid and tetraploid wheat species. PCR analysis of HMW glutenin genes of T. urartu Tuman., T. longissimum (Schweinf. & Muschl.) Bowden and T. speltoides (Tausch) Gren. ex Richt, showed a high degree of length polymorphism, whereas a low degree of length variation was found in accessions of T. tauschii (Coss.) Schmal. Furthermore, using primers specific for the repetitive regions of HMW genes, we could demonstrate that the size variation observed was due to a different length of the central repetitive domain. The usefulness of the PCR-based approach to analyze the genetic polymorphism of HMW glutenin genes, to isolate new allelic variants, to estimate their molecular size and to verify the number of cysteine residues is discussed.