Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects in 2009

IL-25 and CD4(+) TH2 cells enhance type 2 innate lymphoid cell-derived IL-13 production, which promotes IgE-mediated experimental food allergy

BACKGROUND

Food-mediated allergic reactions have emerged as a major health problem. The underlying mechanisms that promote uncontrolled type 2 immune responses to dietary allergens in the gastrointestinal tract remain elusive.

OBJECTIVE

We investigated whether altering IL-25 signaling enhances or attenuates allergic responses to food allergens.

METHODS

Mice of an IL-25 transgenic mouse line (iIL-25Tg mice), which constitutively overexpress intestinal IL-25, and Il17rb(-/-) mice, in which Il17rb gene expression is disrupted, were sensitized and gavage fed with ovalbumin (OVA). We assessed symptomatic characteristics of experimental food allergy, including incidence of diarrhea, incidence of hypothermia, intestinal TH2 immune response, and serum OVA-specific IgE and mast cell protease 1 production.

RESULTS

Rapid induction of Il25 expression in the intestinal epithelium preceded onset of the anaphylactic response to ingested OVA antigen. iIL-25Tg mice were more prone and Il17rb(-/-) mice were more resistant to experimental food allergy. Resident intestinal type 2 innate lymphoid cells (ILC2s) were identified as the major producers of IL-5 and IL-13 in response to IL-25. Reconstituting irradiated wild-type mice with Rora(-/-) or Il17rb(-/-) bone marrow resulted in a deficiency or dysfunction of the ILC2 compartment, respectively, and resistance to experimental food allergy. Repeated intragastric antigen challenge induced a significant increase in numbers of CD4(+) TH2 cells, which enhance IL-25-stimulated IL-13 production by ILC2s ex vivo and in vivo. Finally, reconstituted IL-13-deficient ILC2s had reduced capability to promote allergic inflammation, resulting in increased resistance to experimental food allergy.

CONCLUSION

IL-25 and CD4(+) TH2 cells induced by ingested antigens enhance ILC2-derived IL-13 production, thereby promoting IgE-mediated experimental food allergy.

Food allergy testing

Food allergy (IgE-mediated hypersensitivity) is a common clinical problem affecting approximately 15% of children in the Western world. These hypersensitivity reactions tend to be "immediate" (typically within minutes of food exposure), and clinical features may range from mild to life threatening (anaphylaxis). Detailed clinical history is critical to correct diagnosis. Available laboratory tests have limitations not least poor positive predictive value and limited repertoire. Laboratory tests should support clinical diagno sis not vice versa.

Successful prevention of recurrent anaphylactic events with anti-immunoglobulin E therapy

Anaphylaxis is a fatal and systemic allergic reaction, which can be prevented by avoiding exposure to a causative agent. However, the causative agent cannot be identified in all cases and may be hardly avoided. A 41-year-old man, diagnosed with idiopathic anaphylaxis, experienced 6 anaphylactic events over 7 months, requiring 4 emergency department (ER) visits and 3 epinephrine self-injections. Anti-immunoglobulin E (IgE) therapy was introduced to prevent further anaphylactic events. He experienced no anaphylactic events during 13 months of 4 monthly injections from the beginning until his most recent ER visit because of a similar anaphylactic event. We report a patient who experienced recurrent anaphylactic events that were prevented effectively by anti-IgE therapy with omalizumab. Anti-IgE therapy might be considered as an option to prevent anaphylactic events in patients for whom the causative agent(s) cannot be identified or avoided.

Usefulness of nBos d 4, 5 and nBos d 8 Specific IgE Antibodies in Cow's Milk Allergic Children

PURPOSE

The aim of study was to assess the value of recombinants in predicting the degree of symptoms in children with and without anaphylaxis to cow's milk.

METHODS

The study included 79 children (70±40 months) referred to the Allergological Unit of the Pediatric Department between the years 2008-2012. Group A was composed of 17 children (78±49.6 months) with anaphylaxis after ingestion of milk. Group B was composed of 62 children (73.1±38.6 months) without a history of anaphylaxis, but with less severe symptoms (gastrointestinal and/or skin symptoms). All patients from Group B had a positive open challenge with cow's milk. All patients underwent an allergic evaluation and blood samples were collected to test for IgE to recombinans of milk (nBos d 4, 5, 8).

RESULTS

A significant difference in nBos d 8 emerged with higher levels in Group A (median [IQR]=2.80 [0.91-16.1]) than B (0.65 [0.24-1.67]; P=0.006), whereas there were no statistically significant differences for nBos d 4 and 5. The recombinants' sum was higher in Group A than B: 8.39 [2.72-41.39] vs 3.04 [1.85-7.31] kUA/L; P=0.044. The recombinant nBos d 8 was superior to the other recombinants in identifying children at risk for anaphylaxis, with an area under the curve of 0.718 (95% CI, 0.57-0.86, P=0.006). Considering a cutoff of 1.8 kUA/L, nBos d 8 had the most favorable sensitivity and specificity ratio (sensitivity=0.65, specificity=0.77) with an odd ratio of 6.02 (95% C.I: 1.89-19.23).

CONCLUSIONS

This study suggested 2 phenotypes of allergic children, "high-anaphylaxis-risk" and "milder-risk". These types can be differentiated through measuring the level of IgE to nBos d 8.

An electrochemiluminescence (ECL)-based assay for the specific detection of anti-drug antibodies of the IgE isotype

To address a possible linkage between the occurrence of the hypersensitivity reactions and the induction of IgE anti-drug-antibodies (ADA), a drug specific IgE ADA assay was developed using electrochemiluminescence (ECL) technology. In the assay a drug-specific IgE isotype chimeric antibody was generated and used as an ADA positive control. The biotinylated drug X (an antibody) and ruthenium-labeled omalizumab (an anti-human IgE antibody) were used as capture and detection reagents, respectively. The binding affinities of the chimeric IgE isotype positive control have been shown to be highly comparable to drug X and drug Y (drug X is the 2nd generation of drug Y), indicating that it could serve as a highly useful control to compare and contrast the relative ability of the two generations of drug to elicit IgE ADA responses. The assay cut point factor (CPF) was estimated to be 1.13. The cut point factor derived from normal human serum samples was statistically equivalent to the cut point factor determined from targeted population samples. The assay could detect less than 250ng/mL of IgE antibodies in the presence of 300μg/mL drug X. The assay sensitivity was <0.2ng/mL. A minimal prozone was observed at 100μg/mL IgE ADA, but the sample remained highly detectable. The inter-assay precision was within 12%. The assay was not susceptible to non-specific matrix effects. The performance specifications ensured that the assay was suitable for validation. The combination of the chimeric IgE positive control and the detection antibody (ruthenium-labeled omalizumab) used for the assay could potentially provide a general bioanalytical approach for other biopharmaceuticals for the detection of IgE ADA responses.

A (S)-(+)-decursin derivative, (S)-(+)-3-(3,4-dihydroxy-phenyl)-acrylic acid 2,2-dimethyl-8-oxo-3,4-dihydro-2H,8H-pyrano[3,2-g]-chromen-3-yl-ester, attenuates the development of atopic dermatitis-like lesions in NC/Nga mice

(S)-(+)-decursin is a biological coumarin compound isolated from Angelica gigas Nakai. (S)-(+)-decursin and its analogue have a variety of pharmacological activities. In the present study, the anti-inflammatory effect of a (S)-(+)-decursin derivative, (S)-(+)-3-(3,4-dihydroxy-phenyl)-acrylic acid 2,2-dimethyl-8-oxo-3,4-dihydro-2H,8H-pyrano [3,2-g]-chromen-3-yl-ester (Compound 6, C6), on in vitro and in vivo atopic dermatitis was investigated. C6 suppressed the secretion of IL-6, IL-8, and monocyte chemotactic protein-1 increase by the house dust mite extract in the eosinophilic leukemia cell line and THP-1 cells. C6 inhibited the production of TARC, IL-6, and IL-8 increase by IFN-γ and TNF-α in the human keratinocyte cell line. In the in vivo experiment, NC/Nga mice were sensitized to 2,4-dinitrochlorobenzene, and then C6 or dexamethasone (Dex) were orally and dorsally administered for three weeks. C6 treatment reduced the skin severity score compared with that of the control group. C6 inhibited the thickening of the epidermis and inflammatory cell infiltration into the dermis by evaluating the histological examination. The serum immunoglobulin E (IgE) level decreased in the C6-treated group compared with that of the control group. The inhibitory effect of C6 on IgE concentration was similar to that of Dex. The levels of IL-4, IL-5, IL-13, and eotaxin increased after treatment with concanavalin A in mouse splenocytes. The cytokine levels of the C6-treated group were lower than those of the control group. Taken together, C6 may attenuate atopic dermatitis-like lesions through its anti-inflammatory effect, such as inhibition of IgE and inflammatory cytokines, and it may be valuable as a therapeutic drug for the treatment of atopic dermatitis.

[Update on meat allergy. α-Gal: a new epitope, a new entity?]

The association between the carbohydrate galactose-[alpha]-1,3-galactose (α-Gal) and anaphylaxis was first documented after severe hypersensitivity reactions to cetuximab, a chimeric mouse-human IgG1 monoclonal antibody approved for targeted therapy of carcinomas of colon, as well as of the head and neck region. α-Gal is a ubiquitous glycan moiety expressed on cells and tissue of non-primate mammals. Since this epitope is not expressed in humans, it is very immunogenic for them. α-Gal is located on the Fab portion of cetuximab and thus on the murine part of the chimera. The anaphylactic reactions to the antibody were mediated by IgE specific for α-Gal. Anti-α-Gal-IgE were first detected in sera of patients from the southeastern U.S. and reacted with a wide range of mammalian allergens. The geographic distribution prompted investigations of sensitization routes apart from the ingestion of red meat, such as tick bites und parasitic infections. Anti-α-Gal-IgE seems to be of clinical relevance for allergy to red meat and for the pork-cat syndrome. It is also associated with a novel form of delayed anaphylaxis, which appears more than 3 hours following the ingestion of red meat (beef, pork and lamb), a phenomenon which is still to be elucidated. For most of these patients conventional skin prick tests with commercial reagents proved insufficient for diagnosis.

Intestinal epithelial cell-derived integrin αVβ6 affects the function of dendritic cells

AIM: To investigate the effect of intestinal epithelial cell (IEC)-derived integrin αVβ6 on the biological characteristics of bone marrow-derived dendritic cells (BMDCs).

METHODS: IECs and BMDCs were separated from BALB/c mice and cultured. After IECs were stimulated with ovalbumin (OVA), exosomes were prepared by multiple-step centrifugation. The expression of integrin αVβ6 in exosomes was examined by using the immune colloidal gold technique. Dendritic cells (DCs) were separated using immunomagnetic beads, and the concentration of DCs was determined by flow cytometry. DCs were then divided into five groups: blank group, OVA group, exosomes group, exosomes plus anti-αVβ6 antibody group, and exosomes plus goat anti-mouse IgG group. After these groups of DCs were treated with LPS, the expression of IL-12p70 was detected. In addition, the expression of active and total TGF-β1 was detected before LPS stimulation.

RESULTS: Compared to the blank group, the expression levels of total TGF-β1 increased (both P < 0.05) and those of active TGF-β1 showed no significant changes (both P > 0.05) in the OVA group and exosomes plus anti-αVβ6 antibody group; and the expression levels of both active and total TGF-β1 increased in the exosomes group and exosomes plus goat anti-mouse IgG group (both P < 0.05). Compared to the blank group, the expression of IL-12p70 was significantly reduced (both P < 0.05) in the exosomes group and exosomes plus goat anti-mouse IgG group, but showed no significant changes in the OVA group and exosomes plus anti-αVβ6 antibody group (both P > 0.05) 48 h after stimulation with LPS.

CONCLUSION: Intestinal epithelial cell-derived integrin αVβ6 can increase the expression of active TGF-β1 and total TGF-β1 in DCs and antagonize LPS-induced BMDC maturation.

Does "autoreactivity" play a role in atopic dermatitis?

The role of autoimmunity in atopic dermatitis (AD) is unclear. We sought to critically examine the occurrence, correlation with severity, and possible causative role of autoreactivity in patients with AD. Our systematic review of studies identified from MEDLINE included 31 experiments that described autoreactivity in patients with AD. We defined autoreactivity as in vitro or in vivo evidence of immune response to autologous human, generic human, or recombinant human proteins or other tissue/cellular components. Autoreactivity prevalence in patients with AD ranged from 23% to 91% in 14 studies involving 2644 participants, although it did not appear to vary with age, sex, or disease duration. In contrast to studies of AD, IgE autoreactivity was not found in healthy subjects or in those with allergic rhinoconjunctivitis, psoriasis, systemic lupus erythematosus, or other inflammatory diseases (8 studies of 816 participants). Two reports found a positive correlation between autoreactivity and AD severity. We suggest that autoreactivity might be playing a causative role in AD based on the magnitude and specificity of the associations found; plausible mechanisms through IgE autoantibodies, IgG autoantibodies, and T(H)1 autoreactivity; and experimental elicitation of eczematous lesions after provocation. Whether autoantibodies contribute to AD chronicity now needs to be examined in longitudinal studies.

Inhibitory effect of farnesylthiosalicylic acid on mediators release by mast cells: preferential inhibition of prostaglandin D(2) and tumor necrosis factor-α release

There is substantial evidence suggesting that the Ras inhibitor farnesylthiosalicylic acid (FTS) may modulate various aspects of immune function and inflammation in addition to its well known anti-cancer activity. In this regard, we have recently shown that FTS suppresses T lymphocyte-mediated immune responses. Mast cells (MC), the main effector cells in the elicitation of the allergic response, are known to secrete granule-associated mediators and to release prostaglandins and cytokines on FCεRI-cross-linking, thereby contributing to the pathogenesis of allergic diseases. We hypothesized that MC act as an additional target for FTS. In the present work we analyze the effects of FTS on MC degranulation, prostaglandin release, and cytokine release in vitro, and on the elicitation of IgE-mediated MC dependent cutaneous allergic inflammation in vivo. First we have established that FTS inhibited Ras activation in MC. Next, we have shown that FTS preferentially inhibited prostaglandin (PG) D(2) and tumor necrosis factor (TNF)-α release without having any significant effect on MC β-hexosaminidase secretion. In vivo administration of FTS inhibited the late phase of passive cutaneous anaphylaxis reaction. The time course of FTS-induced inhibition in vivo correlated with mediators release and not with degranulation. This data suggests that FTS may have an inhibitory effect on MC mediated allergic inflammation, and thus may be considered as a possible therapeutic modality.

Combination of allergic factors can worsen diarrheic irritable bowel syndrome: role of barrier defects and mast cells

OBJECTIVES

Recent evidence suggests a role for increased colonic permeability and mucosal mast cell (MC) mediators on symptoms related to the irritable bowel syndrome (IBS). Whether allergic factors (AFs) are involved in the pathophysiology of IBS is unclear. We addressed the question of the possible influence of an allergic background on IBS symptoms.

METHODS

We assessed paracellular permeability, mucosal MCs counts, and spontaneous release of tryptase of colonic biopsy specimens in 34 IBS patients and 15 healthy subjects. The severity of IBS was assessed through self-reported questionnaires. All individuals were tested for the presence of AF, including self-perception of adverse reaction to food, personal and familial history of atopic disease, elevated total or specific immunoglobulin E against food/inhalant antigens, blood eosinophilia, and skin tests.

RESULTS

IBS patients had significant enhanced colonic permeability, higher number of MCs, and spontaneous release of tryptase than healthy subjects. The severity of IBS was significantly correlated with colonic permeability (r=0.48, P=0.004), MCs counts (r=0.36, P=0.03), and tryptase (r=0.48, P=0.01). In 13 IBS patients (38.2%) having at least three AFs, symptoms scores, colonic permeability, MCs counts, and tryptase release by colonic biopsies were significantly higher than in those with less than three AFs. IBS patients with at least three AFs were more prone to diarrhea or alternating symptoms. None AF was found to be predictive of IBS severity.

CONCLUSIONS

In IBS patients, the presence of an allergic background correlates with a more severe disease and diarrhea predominance, possibly by enhancing mucosal MC activation and paracellular permeability.

Evidence-based evaluation and management of chronic urticaria in children

Urticaria affects nearly 25% of the population at some time in their lives. In a subset of children, urticaria will develop into a chronic condition that can greatly affect quality of life. Although numerous causes and triggers are proposed for chronic urticaria (CU) in children, ranging from infections, allergens, and medications to physical factors and autoimmune disease, the exact etiology is not always identifiable. Accordingly, a large subset of cases are designated "chronic idiopathic urticaria." Because of the clinical complexities of CU, as well as the confusing literature on this topic, we have developed a conceptual framework based on the cumulative evidence to assist with the categorization, clinical evaluation, and treatment of CU in children.

Pathophysiology of allergic inflammation

Allergic inflammation is due to a complex interplay between several inflammatory cells, including mast cells, basophils, lymphocytes, dendritic cells, eosinophils, and sometimes neutrophils. These cells produce multiple inflammatory mediators, including lipids, purines, cytokines, chemokines, and reactive oxygen species. Allergic inflammation affects target cells, such as epithelial cells, fibroblasts, vascular cells, and airway smooth muscle cells, which become an important source of inflammatory mediators. Sensory nerves are sensitized and activated during allergic inflammation and produce symptoms. Allergic inflammatory responses are orchestrated by several transcription factors, particularly NF-κB and GATA3. Inflammatory genes are also regulated by epigenetic mechanisms, including DNA methylation and histone modifications. There are several endogenous anti-inflammatory mechanisms, including anti-inflammatory lipids and cytokines, which may be defective in allergic disease, thus amplifying and perpetuating the inflammation. Better understanding of the pathophysiology of allergic inflammation has identified new therapeutic targets but developing effective novel therapies has been challenging. Corticosteroids are highly effective with a broad spectrum of anti-inflammatory effects, including epigenetic modulation of the inflammatory response and suppression of GATA3.

Evaluation of the irritating influence of carane derivatives and their antioxidant properties in a deoxyribose degradation test

Previous studies of the propranolol monoterpene derivative (-)-4-[2-hydroxy-3-(N-isopropylamino)-propoxyimino]-cis-carane hydrochloride (KP-23) and its diastereoisomers, KP-23R and KP-23S, demonstrated different effects on the cyclic AMP generating system as well as anti-inflammatory, analgesic, antihistaminic and antioxidant activity. The present study examined the influence of KP-23 and its diastereoisomers KP-23R and KP-23S on the skin-irritating activity and the mucous membrane-irritating activity as well as their influence on a late-type contact allergy in the in vivo tests. The hydroxyl radical scavenging potential of the three analogues was evaluated using their ability to inhibit Fe(II)/H2O2-induced oxidative degradation of 2-deoxyribose (2-DR) in the in vitro tests. The results obtained indicated that the hydroxyamine carane derivative did not evoke irritative changes and did not induce a late-type contact allergy in the guinea-pig. Diastereoisomers of KP-23 exhibit antioxidant properties in a dose-dependent manner and protected against OH-radicals generated from the Fenton reaction.

Technical advance: soluble OX40 molecule mimics regulatory T cell modulatory activity on FcεRI-dependent mast cell degranulation

Tregs play a central role in modulating FcεRI-dependent MC effector functions in the course of the allergic response. Cellular interaction depends on the constitutive expression of OX40 on Tregs and the OX40L counterpart on MCs. Study of OX40L signaling on MCs is hampered by the need of a highly purified molecule, which triggers OX40L specifically. We now report that sOX40 mimics the physiological activity of Treg interaction by binding to activated MCs. When treated with sOX40, activated MCs showed decreased degranulation and Ca(++) influx, whereas PLC-γ2 phosphorylation remained unaffected. Once injected into experimental animals, sOX40 not only located within the endothelium but also in parenchyma, where it could be found in close proximity and apparently bound to MCs. This soluble molecule triggers MC-OX40L without the requirement of Tregs, thus allowing study of OX40L signaling pathways in MCs and in other OX40L-expressing cell populations. Importantly, as sOX40 inhibits MC degranulation, it may provide an in vivo therapeutic tool in allergic disease.

Food allergy: which tests are worth doing and which are not?

Adverse reactions to foods may arise by a variety of mechanisms, both immune (IgE and non-IgE) and non-immune mediated. This article considers those assays useful in the diagnosis of Type 1 hypersensitivity to foods (IgE-based) and, importantly, discusses those assays where evidence is lacking for their use. In all cases of suspected food allergy, a full clinical history is indispensable in facilitating diagnosis. Total serum IgE is not a suitable screen for food allergy. Suspect allergens may be confirmed by either skin prick testing or serological assays for specific IgE. Several studies suggest concentrations of food-specific IgE at which there is a high probability of reaction on food challenge. These cut-off levels are now being used by physicians to direct clinical advice. However, it is important to note that not all studies agree on these limits and the chosen cut-off is dependent on the population studied and the assay used.

IL-9(+) IL-10(+) T cells link immediate allergic response to late phase reaction

The mechanism underlying late-phase allergic reactions (LPR) remains incompletely understood. This study aimed to investigate the role of a newly described subset of T cells, interleukin (IL)-9(+) IL-10(+) T cells, in the pathogenesis of LPR. Using a T helper type 2 (Th2) inflammatory mouse model, we examined the frequency of IL-9(+) IL-10(+) T cells in the jejunum by immunohistochemistry. The LPR in the jejunum was observed afterwards. The cytokine profile of IL-9(+) IL-10(+) T cells was characterized and the major cytokine that plays the critical role in the initiation of LPR was investigated. Abundant IL-9(+) IL-10(+) T cells as well as inflammatory cell extravasation in the jejunal sections were observed in sensitized mice 48 h after specific antigen challenge. IL-9(+) IL-10(+) T cells expressed high levels of macrophage inflammatory protein 1 (MIP1) that could be enhanced by T cell receptor activation. MIP1 facilitated macrophage extravasation in local tissue. Macrophage-derived MIP2 contributed to neutrophil infiltration in the intestine in LPR. Pretreatment with anti-MIP antibody inhibited the LPR in the intestine. IL-9(+) IL-10(+) T cells play an important role in LPR. This subset of T cells has the potential to be a novel therapeutic target in the treatment of LPR and LPR-related inflammation.

Future therapies for food allergies

Food allergy is an increasingly prevalent problem in westernized countries, and there is an unmet medical need for an effective form of therapy. A number of therapeutic strategies are under investigation targeting foods that most frequently provoke severe IgE-mediated anaphylactic reactions (peanut, tree nuts, and shellfish) or are most common in children, such as cow's milk and hen's egg. Approaches being pursued are both food allergen specific and nonspecific. Allergen-specific approaches include oral, sublingual, and epicutaneous immunotherapy (desensitization) with native food allergens and mutated recombinant proteins, which have decreased IgE-binding activity, coadministered within heat-killed Escherichia coli to generate maximum immune response. Diets containing extensively heated (baked) milk and egg represent an alternative approach to food oral immunotherapy and are already changing the paradigm of strict dietary avoidance for patients with food allergy. Nonspecific approaches include monoclonal anti-IgE antibodies, which might increase the threshold dose for food allergen in patients with food allergy, and a Chinese herbal formulation, which prevented peanut-induced anaphylaxis in a murine model and is currently being investigated in clinical trials. The variety of strategies for treating food allergy increases the likelihood of success and gives hope that accomplishing an effective therapy for food allergy is within reach.