Analysis of altered miRNA profiling in the colon of a mouse model with β-lactoglobulin allergy

OBJECTIVES

The differences in the expression profiles of colonic miRNAs between β-lactoglobulin (β-Lg) allergic mice and normal mice were analyzed to investigate the important role of the miRNA regulation mechanism in the pathogenesis of cow's milk allergy.

METHODS

The present study performed Illumina sequencing to characterize the miRNA profile changes in mouse colon responding to β-Lg challenge. Target genes were predicted by TargetScan 50 and miRanda 3.3a algorithms and assessed by GO and KEGG analysis. The expression levels of selected miRNAs and cytokine production were verified by cell transfection and quantitative RT-PCR.

RESULTS

A total of 15 miRNAs were diversely expressed between the colon of the normal and β-Lg-sensitized mice (P < 0.05, fold change of >1.50 or <0.67), including six up-regulated miRNAs and nine down-regulated miRNAs, among which seven miRNAs were validated using qRT-PCR. GO enrichment and KEGG pathway analyses further revealed that biological process, protein binding, cytoplasm and the pathways of cancer were significantly enriched, which were closely connected to the allergic inflammation development. Additionally, six key functional interaction pairs in β-Lg allergy were identified in miRNA prediction algorithms and verified using qRT-PCR.

CONCLUSIONS

We can conclude that our results suggested that the miRNAs regulation network participated in the pathogenesis of cow's milk allergy.

Biodegradable microparticles for the mucosal delivery of antibacterial and dietary antigens

Mucosal administration of antigen is known to be appropriate for vaccine purposes as well as tolerance induction. Biodegradable poly(DL-lactide-co-glycolide) (PLGA) microparticles were used to deliver both antibacterial phosphorylcholine (PC) and dietary antigen beta lactoglobulin (BLG) by mucosal route. In a first study, the protective immunity elicited by intragastric vaccination with PC encapsulated in microparticles was evaluated in a mouse model against intestinal infection by Salmonella typhimurium and pulmonary infection by Streptococcus pneumoniae. A significant rise in anti-PC immunoglobulin A (IgA) titers, as measured by an enzyme-linked immunosorbent assay, was observed in the intestinal secretions after oral immunization with PC-loaded microparticles compared with the titers of mice immunized with free PC-thyr or blank microparticles. This antibody response correlated with a highly significant resistance to oral challenge by S. typhimurium. IgA in pulmonary secretion were not able to protect against S. pneumoniae infection. BALB/c mice were, therefore, immunized intranasally (i.n.). Immunization was followed by a rise in anti-PC IgA and IgG titers in serum and in pulmonary secretions by both free and encapsulated PC-Thyr. The survival rates were 91 and 76% in the two groups of mice, respectively. In a second study and in order to prevent allergy against milk by inducing oral tolerance, one of the major allergenic milk protein, BLG was entrapped into microparticles. Oral administration of microparticles containing BLG reduced significantly (by 10000) the amount of protein necessary to decrease both specific anti BLG IgE and DTH response. These studies demonstrate the ability of microparticles to induce both mucosal immunity and oral tolerance.

Detection of potentially allergenic material in 12 hydrolyzed milk formulas

Hypoallergenic milk formulas are used as an alternative diet for infants who have allergies to cow's milk when breast-feeding is not possible. These products are based on proteins, which have been heat-treated and hydrolyzed to a different degree in order to cleave antibody-binding structures. Even extensively hydrolyzed products have occasionally been observed to elicit allergic reactions in sensitized infants, however. Therefore, the parameters of relevance to allergenic potential require more investigation. The objective of the present study was to investigate 12 different hydrolyzed milk formulas for their contents of potentially allergenic protein material, i.e. material that may induce allergenicity or elicit allergic responses in already sensitized individuals. Analytical methods applied were gel filtration, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), native PAGE, immunoblotting, dot-immunobinding, and ELISA. Care was taken to assure that all protein fractions were investigated, including supernatants and precipitates following centrifugation of the milk formulas. By gel filtration, protein material with apparent molecular masses of 7 to >30 kDa was detected. Analysis by SDS-PAGE of formula precipitates showed that proteins with a molecular mass above 20 kDa were present even in some of the extensively hydrolyzed formulas. Residual antigenic beta-lactoglobulin was found by ELISA in all products. By immunoblotting and dot-immunobinding with antibodies against total whey, caseins, or Kunitz soybean trypsin inhibitor, we observed antigenic material mainly in partially hydrolyzed products. We concluded that SDS-PAGE of formula supernatants and precipitates gave the most differentiated profile of hydrolyzed formulas and that this method is well suited for screening potential allergenicity.

Development of immunoglobulin G and immunoglobulin E antibodies to cow's milk proteins and ovalbumin after a temporary neonatal exposure to hydrolyzed and whole cow's milk proteins

The ingestion of food antigens usually results in the induction of oral tolerance, but the clinical and immunologic consequences of brief exposure to cow's milk proteins during the neonatal period are not well-documented. The aim of this work was to study immunoglobulin (Ig)E and IgG responses to cow's milk proteins and ovalbumin after exposure during the first three days of life in infants who were otherwise exclusively breast-fed. A group of 129 infants was randomly assigned at birth to one of three feeding regimens: human milk (HM), cow's milk formula (CMF), or a casein hydrolysate formula (CHF), during the first three days of life. They were then all exclusively breast-fed for a varying period of time and followed for two years. Serum IgG and IgE antibodies to cow's milk proteins and ovalbumin (OVA) were analyzed in blood samples obtained at birth, at 4 days and at 2, 4, 8, 12 and 24 months of age. The levels of IgG antibodies to beta-lactoglobulin (IgG-BLG) and bovine serum albumin (IgG-BSA) were higher in the CMF and the HM groups than in the CHF group for up to two years. This was particularly obvious for IgG-BLG in infants who started weaning before two months. The levels of IgG antibodies to casein (IgG-CAS) were higher in the CMF group, as compared with the CHF group at 8 and 12 months. The levels of IgG antibodies to OVA were similar in all three feeding groups. The levels of IgE antibodies to CAS or OVA were similar in the three feeding groups. Exposure to cow's milk during the first three days of life stimulated IgG antibody production to cow's milk proteins and this was still obvious at 2 years of age, while feeding with a casein hydrolysate during the first three days of life was associated with low levels of IgG antibodies to cow's milk proteins.

Allergy to bovine beta-lactoglobulin: specificity of human IgE to tryptic peptides

BACKGROUND

Bovine beta-lactoglobulin (Blg) is a major cow's milk allergen. It is the main whey protein, without any counterpart in human milk. Blg chemical hydrolysates appeared to retain most of the immunoreactivity of the native protein. Allergenicity of Blg has already been shown to be associated with the four peptides derived from cyanogen bromide cleavage of Blg.

OBJECTIVES

To map the major allergenic epitopes (e.g. regions of the molecule able to bind IgE) on Blg using specific IgE from sera of 46 milk-allergic patients as a probe.

METHODS

Direct and competitive inhibition enzyme immunoassays involving immobilized native protein or purified peptides derived from Blg tryptic cleavage.

RESULTS

Several peptides capable of specifically binding human IgEs were identified and were classified according to the intensity and frequency of the responses. The major epitopes appeared to be fragments (41-60), (102-124) and (149-162) recognized by 92, 97 and 89% of sera, respectively, whilst a second group which contained the fragments (1-8) and (25-40) was recognized by 58 and 72% of the population. A third group, comprising peptides (9-14), (84-91) and (92-100), was still detected by more than 40% of sera.

CONCLUSION

Three peptides were identified as major epitopes, recognized by a large majority of human IgE antibodies. Numerous other epitopes are scattered all along the Blg sequence.

Cord blood mononuclear cell responsiveness to beta-lactoglobulin: T-cell activity in 'atopy-prone' and 'non-atopy-prone' newborns

We have studied the T-cell-mediated response to the major allergen of cow's milk, in a group of newborns at risk of developing cow's milk allergy, and in a control group. Before any atopic status has developed, we observe beta-lactoglobulin-specific primary proliferation only in the group at risk for food-related allergies. In this group, the capability to proliferate is not due to placental transmission of 'factors' from allergic mothers. The recognition of the tested beta-lactoglobulin peptides does not show major differences between the responder and nonresponder populations. In the responder population, the response to p145-161 appears linked to a primary response to ovalbumin, another frequent food allergen. On the basis of our findings, we propose a model in which development of allergic diseases is linked to an alteration of T-cell activation through the engagement by the antigen; the HLA phenotype determines the allergen(s) involved, and other genetic or environmental factors dictate the clinical characteristics of the disease.

Protective action of diosmectite treatment on digestive disturbances induced by intestinal anaphylaxis in the guinea-pig

METHODS

Colonic transit time, faecal moisture and intestinal permeability were assessed in guinea-pigs sensitized intraperitoneally with cow's milk and challenged with an oral administration of beta-lactoglobulin. One group of animals was treated for 1 week with diosmectite (500 mg.kg/day) and another with placebo. A control group was not sensitized but treated with diosmectite.

RESULTS

In sensitized animals receiving placebo, challenge with beta-lactoglobulin induced a significant (P < 0.05) decrease in colonic transit time, and increases in faecal moisture and intestinal permeability. These changes were not observed in animals treated with diosmectite.

CONCLUSION

Diosmectite pre-treatment protects against allergic digestive disturbances induced by antigen administration in guinea-pigs sensitized to cow's milk.

Anaphylactic colonic hypersecretion in cow's milk sensitized guinea-pigs depends upon release of interleukin-1, prostaglandins and mast cell degranulation

METHODS

The effect of beta-lactoglobulin (beta-LGI) challenge on net water movements into the proximal colon and the role of Interleukin-1 (IL-1), prostaglandins and mast cell degranulation on the challenge-induced net water changes were assessed in vivo using isolated colonic loops in anaesthetized guinea-pigs immunized to bovine milk.

RESULTS

beta-lactoglobulin challenge infused into the colonic loop during 30 min reversed the net water flux into a net secretion during the period of antigen infusion. Doxantrazole, a mast cell stabilizing agent, administered 120 min before challenge infusion, suppressed challenge-induced hypersecretion. Similarly recombinant IL-1 receptor antagonist protein abolished the antigen-induced colonic secretory effect. Indomethacin, a prostaglandin synthesis inhibitor, administered 20 min prior to antigen infusion, significantly (P < 0.05) reduced, but did not abolish, the challenge-induced colonic secretory effect.

CONCLUSIONS

These results suggest that IL-1 plays an important role in antigen challenge-induced colonic hypersecretion which involves mast cell degranulation and prostaglandin release.

Hypersensitivity reactions from inhalation of milk proteins

We describe the case of a young man with IGE-mediated hypersensitivity to milk, casein, and lactoglobulin, who went into respiratory crisis every time he milked his sheep.

Ability of a new infant formula prepared from partially hydrolyzed bovine whey to induce anaphylactic sensitization: evaluation in a guinea pig model

In the present study we evaluated the allergenicity and immunogenicity of a whey partially hydrolysate formula (PHF) in a guinea pig model. Nine groups of 10 guinea pigs received either a conventional milk formula (CMF) or PHF for 37 days. After intravenous (i.v.) challenge with either beta-lactoglobulin (beta-L) or ultracentrifuged (u)CMF, animals fed CMF showed, respectively, 80% and 100% fatal reactions, whereas animals fed PHF showed no reactions when i.v. challenged both with beta-L and uPHF. Eighty percent fatal reactions, and 10%, respectively, of severe and mild reactions have been observed in the CMF-fed, casein-challenge group. In contrast, only one (10%) mild reaction occurred in the PHF-fed, casein-challenged group. When challenged with u-pasteurized cow's milk (uPCM), CMF-fed animals showed 86% fatal reactions and 14% mild reactions, whereas PHF-fed ones presented 70% no reactions, 20% mild reactions, and one (10%) fatal reaction. Animals fed CMF showed a significantly higher level of specific IgG against cow's milk antigens than PHF-fed ones, which, however, presented higher levels of antibodies than a water-supplemented control group. The present results confirm that PHF is less sensitizing than CMF in a guinea pig model.

Prevention of allergic sensitization to beta-lactoglobulin with conjugates made of beta-lactoglobulin coupled to isologous immunoglobulin G

We have shown that, under certain conditions, a single dose of a conjugate of beta-lactoglobulin linked to isologous IgG suppresses specific antibody responses (IgE, IgG, and IgA) in rats immunized with beta-lactoglobulin. This suppression is allergen specific. It also appears to be effective when animals are first immunized and then tolerized. In addition, administration of the beta-lactoglobulin-IgG tolerogen abolishes mast cell mediator release. This has been shown both in vivo and with passively sensitized mast cells in vitro. We propose that the construction of a tolerogen made of whole protein allergen linked to IgG could provide a novel specific therapy for allergic reactions.

Recombinant interleukin-1 receptor antagonist protein prevents sensitization and intestinal anaphylaxis in guinea pigs

Recombinant interleukin-1 receptor antagonist protein (rlRAP, 0.5 mg/kg) administered intraperitoneally in guinea pigs one hour before primary and booster parenteral sensitization (1 ml) by cow milk, led to a reduced immunoglobulin E (IgE) production, as displayed by a passive cutaneous anaphylaxis test. rlRAP administered intraperitoneally in sensitized guinea pigs at 0.5 mg/kg 10 min before challenge administration (beta-lactoglobulin, 100 mg per os), also prevents the colonic motor and secretory changes induced by intestinal anaphylaxis. These results suggest the involvement of interleukin-1 in food allergy and evidence a double protective role for rlRAP in food hypersensitivity.

Immunologic changes associated with the development of tolerance in children with cow milk allergy

The purpose of this study was to determine whether cow milk-specific antibody responses correlated with the development of clinical tolerance in cow milk-allergic children. Double-blind, placebo-controlled food challenges were performed annually in 29 patients with cow milk allergy. Clinical reactivity was lost in 11 (38%) of 29 patients. The median age for all patients at the time of diagnosis by these food challenges was 3 years; more than 80% of patients in each group had atopic dermatitis as part of their presenting symptoms. Casein-specific and beta-lactoglobulin-specific IgE, IgG, IgG1, and IgG4 antibody concentrations were analyzed in all patients at regular intervals. In the patients becoming clinically tolerant to cow milk, the IgE-specific antibody concentrations and IgE/IgG-specific ratios for both milk proteins were lower initially and decreased significantly with time, in comparison with those in the group who retained clinical sensitivity. The concentrations of IgG1- and IgG4-specific antibody to casein and the IgE/IgG1 and IgE/IgG4 ratios for both casein and beta-lactoglobulin were significantly less in the patients losing clinical reactivity. No differences in the IgG-specific concentrations were observed in either group at any of the evaluation times noted above. Monitoring similar casein-specific and beta-lactoglobulin-specific IgE concentrations and IgE/IgG ratios may help predict which patients will ultimately lose their clinical reactivity to cow milk.

Inducement test in cow's milk allergy

Results of practical tests with whole milk and the three most allergenic proteins were compared in 32 children who were suspected of showing allergy to milk. Diagnosis was composed of a suggestive clinical history, familial atopy, positive in vitro and in vivo tests and regression of symptoms under an exclusion diet. Tests of re-introduction were done with 11 children. Better agreement between the provocation tests and the other elements of the diagnosis was found when the tests were made with the fractions, rather than whole milk. Furthermore, the finding of reduced allergy to casein allows consideration of re-introduction of milk in the form of cheese.

[Results of the study of preventive effectiveness and side effects of anti-influenza lactoglobulin in controlled epidemiologic trial]

Prophylactic activity and side action of antiinfluenza lactoglobulin were studied under conditions of controlled epidemiological trial in 6361 persons during the epidemiological rise of influenza incidence. The data obtained pointed to the absence of any protective effect of antiinfluenza lactoglobulin. Marked allergenic properties of lactoglobulin and development of sensitization in the persons under observation were found during the study of the side-effect of the preparation. Thus, the absence of prophylactic efficacy and the sensitizing action of antiinfluenza lactoglobulin pointed to the inexpediency of its use for prophylactic and therapeutic purpose.

Milk allergy in infants and young children. Current knowledge

Milk allergy can be overcome easily if one develops a high index of suspicion which leads to early diagnosis. Avail able treatments make the outcome uniformly successful.