Dissecting mechanisms underlying the pathogenesis of eosinophilic esophagitis (HYP6P.263)

Eosinophilic esophagitis (EoE) is an allergic disease characterized by esophageal eosinophilia, inflammation, and dysfunction. EoE has become increasingly common, but current management strategies are nonspecific. Thus, there is an urgent need to identify new pathways that could be targeted to treat EoE. Recently, EoE was associated with a gain-of-function polymorphism in the gene that encodes thymic stromal lymphopoietin (TSLP), a cytokine that promotes allergic inflammation and peripheral basophilia. However, how TSLP and basophils might contribute to the development of eosinophil responses during EoE remains unknown. Here, we employed a new murine model of EoE-like disease to investigate the role of TSLP and basophils in promoting esophageal eosinophil responses. Development of esophageal eosinophil responses was dependent on TSLP-elicited basophils, and antibody-mediated neutralization of TSLP or depletion of basophils ameliorated established esophageal eosinophilia. In addition, we examined how sort-purified human basophils influence eosinophil responses in vitro. Finally, elevated TSLP levels and exaggerated basophil responses observed in esophageal biopsies from EoE patients correlated with eosinophil responses. Together, these data indicate that TSLP-elicited basophil responses may play a key role in mediating eosinophil responses in EoE, suggesting that the TSLP-basophil axis could represent a new and promising therapeutic target to treat this disease.

Thymic stromal lymphopoietin-mediated extramedullary hematopoiesis promotes allergic inflammation

Extramedullary hematopoiesis (EMH) refers to the differentiation of hematopoietic stem cells (HSCs) into effector cells that occurs in compartments outside of the bone marrow. Previous studies linked pattern-recognition receptor (PRR)-expressing HSCs, EMH, and immune responses to microbial stimuli. However, whether EMH operates in broader immune contexts remains unknown. Here, we demonstrate a previously unrecognized role for thymic stromal lymphopoietin (TSLP) in promoting the population expansion of progenitor cells in the periphery and identify that TSLP-elicited progenitors differentiated into effector cells including macrophages, dendritic cells, and granulocytes and that these cells contributed to type 2 cytokine responses. The frequency of circulating progenitor cells was also increased in allergic patients with a gain-of-function polymorphism in TSLP, suggesting the TSLP-EMH pathway might operate in human disease. These data identify that TSLP-induced EMH contributes to the development of allergic inflammation and indicate that EMH is a conserved mechanism of innate immunity.

Eosinophilic esophagitis

OBJECTIVE

To review the understanding of the pathogenesis of eosinophilic esophagitis (EoE) and the role of the immune system in the disease process.

DATA SOURCES

Peer-reviewed articles on EoE from PubMed searching for "Eosinophilic Esophagitis and fibrosis" in the period of 1995 to 2013.

STUDY SELECTIONS

Studies on the clinical and immunologic features, pathogenesis, and management of EoE.

RESULTS

Recent work has revealed that thymic stromal lymphopoietin and basophil have an increased role in the pathogenesis of disease. Additional understanding on the role of fibrosis in EoE is emerging.

CONCLUSION

The incidence of EoE is increasing like most atopic disease. Similar to other allergic diseases, EoE is treated with topical steroids and/or allergen avoidance.

Oral food challenge to wheat: a near-fatal anaphylaxis and review of 93 food challenges in children

Background

Wheat allergy is among the most common food allergy in children, but few publications are available assessing the risk of anaphylaxis due to wheat.

Methods

In this study, we report the case of near-fatal anaphylaxis to wheat in a patient undergoing an oral food challenge (OFC) after the ingestion of a low dose (256 mg) of wheat. Moreover, for the first time, we analyzed the risk of anaphylaxis during an OFC to wheat in 93 children, compared to other more commonly challenged foods such as milk, egg, peanuts, and soy in more than 1000 patients.

Results

This study, which includes a large number of OFCs to wheat, shows that wheat is an independent risk factor that is associated with anaphylaxis requiring epinephrine administration (Odds Ratio [OR] = 2.4) and anaphylaxis requiring epinephrine administration to low dose antigen (OR = 8.02). Other risk factors for anaphylaxis, anaphylaxis requiring epinephrine administration, and anaphylaxis to low dose antigen was a history of a prior reaction not involving only the skin (OR = 1.8, 1.9 and 1.8 respectively). None of the clinical variables available prior to performing the OFC could predict which children among those undergoing OFCs to wheat would develop anaphylaxis or anaphylaxis for low dose antigen.

Conclusion

This study shows that wheat is an independent risk factor that is associated with anaphylaxis requiring epinephrine administration and anaphylaxis requiring epinephrine administration to low dose antigen.

Thymic stromal lymphopoietin-elicited basophil responses promote eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a food allergy-associated inflammatory disease characterized by esophageal eosinophilia. Current management strategies for EoE are nonspecific, and thus there is a need to identify specific immunological pathways that could be targeted to treat this disease. EoE is associated with polymorphisms in the gene that encodes thymic stromal lymphopoietin (TSLP), a cytokine that promotes allergic inflammation, but how TSLP might contribute to EoE disease pathogenesis has been unclear. Here, we describe a new mouse model of EoE-like disease that developed independently of IgE, but was dependent on TSLP and basophils, as targeting TSLP or basophils during the sensitization phase limited disease. Notably, therapeutic TSLP neutralization or basophil depletion also ameliorated established EoE-like disease. In human subjects with EoE, we observed elevated TSLP expression and exaggerated basophil responses in esophageal biopsies, and a gain-of-function TSLP polymorphism was associated with increased basophil responses in patients with EoE. Together, these data suggest that the TSLP-basophil axis contributes to the pathogenesis of EoE and could be therapeutically targeted to treat this disease.

Food-induced anaphylaxis

Food-induced anaphylaxis (FIA) is a serious allergic reaction that may cause death rapidly in otherwise healthy individuals. There is no universal agreement on its definition or criteria for diagnosis. Hospital admissions for FIA have more than doubled in the last decade. Food is one of the most common causes of anaphylaxis, with most surveys indicating that food-induced reactions account for 30% to 50% of cases. The most commonly implicated foods are peanut, tree nuts, milk, eggs, sesame seeds, fish, and shellfish. The only life-saving treatment for anaphylaxis is allergen avoidance, and epinephrine injection if an anaphylactic event occurs.

Predictive values for food challenge-induced severe reactions: development of a simple food challenge score

BACKGROUND

Skin-prick tests (SPT), food-specific immunoglobulin E level (sIgE) and clinical history have limited value individually in predicting the severity of outcome of the oral food challenge (OFC).

OBJECTIVES

To develop a score that accounts for SPT, sIgE and clinical history to predict the risk of severe reaction to the OFC.

METHODS

A 5 year retrospective chart review was performed on 983 children who underwent OFC to egg, milk and peanut.

RESULTS

Using multilogistic regression, four major indicators were found to be independently associated with failed OFC: sIgE (odds ratio = 1.04, P < 0.0001), wheal size of the SPT (OR = 1.23, P < 0.0001), a history of any prior reaction to the food (OR = 1.13, P < 0.01), and a history of a prior non-cutaneous reaction (OR = 1.99, P < 0.01); and three were independently associated with anaphylaxis: wheal size (OR = 1.16, P < 0.001), a history of a prior non-cutaneous reaction (OR = 4.24, P < 0.01), and age (OR = 1.07, P < 0.03). A Food Challenge Score (0-4) was developed which accounted for SPT wheal, sIgE, a history of a prior non-cutaneous reaction, and age. A score of 0-1 had a negative predictive value for multisystem reaction to the OFC: 95% for milk, 91% for egg and 93% for peanut. A score of 3-4 had a positive predictive value for anaphylaxis: 62% for milk, 92% for egg and 86% for peanut.

CONCLUSIONS

Severe reaction to milk, egg and peanut OFC can be predicted using a simple score that takes into account clinical data that are commonly available prior to the challenges.

Severe malnutrition resulting from use of rice milk in food elimination diets for atopic dermatitis

Alternatives to cow's milk and soy milk are often necessary for children with food allergies. Although hydrolyzed and elemental formulas are appropriate replacements, other milk products such as rice and almond milk are insufficient protein sources for children under 2 years of age. A chart review on three patients treated for protein malnutrition in association with multiple diagnosed food allergies that resulted in refractory eczema revealed adverse outcomes that resulted from elimination diets. The use of rice milk resulted in hypoalbuminemia and poor weight gain in all cases, and multiple secondary infections in one patient. These cases illustrate the need for careful nutritional guidance in the management of food allergy, as well as the importance of cautious use and interpretation of testing for food allergies in the absence of a clear clinical history of reaction.

Invariant natural killer T cells from children with versus without food allergy exhibit differential responsiveness to milk-derived sphingomyelin

BACKGROUND

A key immunologic feature of food allergy (FA) is the presence of a T(h)2-type cytokine bias. Ligation of the invariant natural killer T cell (iNKT) T-cell receptor (TCR) by sphingolipids presented via the CD1d molecule leads to copious secretion of T(h)2-type cytokines. Major food allergens (eg, milk, egg) are the richest dietary source of sphingolipids (food-derived sphingolipids [food-SLs]). Nonetheless, the role of iNKTs in FA is unknown.

OBJECTIVE

To investigate the role of iNKTs in FA and to assess whether food-SL-CD1d complexes can engage the iNKT-TCR and induce iNKT functions.

METHODS

PBMCs from 15 children with cow's milk allergy (MA), 12 children tolerant to cow's milk but with allergy to egg, and 13 healthy controls were incubated with α-galactosylceramide (αGal), cow's milk-sphingomyelin, or hen's egg-ceramide. iNKTs were quantified, and their cytokine production and proliferation were assessed. Human CD1d tetramers loaded with milk-sphingomyelin or egg-ceramide were used to determine food-SL binding to the iNKT-TCR.

RESULTS

Milk-sphingomyelin, but not egg-ceramide, can engage the iNKT-TCR and induce iNKT proliferation and T(h)2-type cytokine secretion. Children with FA, especially those with MA, had significantly fewer peripheral blood iNKTs and their iNKTs exhibited a greater T(h)2 response to αGal and milk-sphingomyelin than iNKTs of healthy controls.

CONCLUSION

iNKTs from children with FA, especially those with MA, are reduced in number and exhibit a T(h)2 bias in response to αGal and milk-sphingomyelin. These data suggest a potential role for iNKTs in FA.

Food allergy: review, classification and diagnosis

Food allergies, defined as an immune response to food proteins, affect as many as 8% of young children and 2% of adults in westernized countries, and their prevalence appears to be rising like all allergic diseases. In addition to well-recognized urticaria and anaphylaxis triggered by IgE antibody-mediated immune responses, there is an increasing recognition of cell-mediated disorders such as eosinophilic esophagitis and food protein-induced enterocolitis. New knowledge is being developed on the pathogenesis of both IgE and non-IgE mediated disease. Currently, management of food allergies consists of educating the patient to avoid ingesting the responsible allergen and initiating therapy if ingestion occurs. However, novel strategies are being studied, including sublingual/oral immunotherapy and others with a hope for future.

Urticaria and urticaria related skin condition/disease in children

Urticaria is a rash, that typically involves skin and mucosa, and is characterized by lesions known as hives or wheals. In some cases there is an involvement of deep dermis and subcutaneous tissue that causes a skin/mucosa manifestation called angioedema. Urticaria and angioedema are very often associated: urticaria-angioedema syndrome. The acute episodic form is the most prevalent in the pediatric population, and it is often a recurrent phenomenon (recurrent urticaria). Acute episodic urticaria it is usually triggered by viruses, allergic reactions to foods and drugs, contact with chemicals and irritants, or physical stimuli. In many instances it is not possible to identify a specific cause (idiopathic urticaria). Chronic urticaria is a condition that can be very disambling when severe. In children is caused by physical factors in 5-10% of cases. Other trigger factors are infections, foods, additives, aeroallergens and drugs. The causative factor for chronic urticaria is identified in about 20% of cases. About one-third of children with chronic urticaria have circulating functional autoantibodies against the high affinity IgE receptor or against IgE. (chronic urticaria with autoantibodies or "autoimmune" urticaria). It is not known why such antibodies are produced, or if the presence of these antibodies alter the course of the disease or influence the response to treatment. Urticaria and angioedema can be symptoms of systemic diseases (collagenopathies, endocrinopathies, tumors, hemolytic diseases, celiachia) or can be congenital (cold induced familiar urticaria, hereditary angioedema). The diagnosis is based on patient personal history and it is very important to spend time documenting this in detail. Different urticaria clinical features must guide the diagnostic work-up and there is no need to use the same blood tests for all cases of urticaria. The urticaria treatment includes identification of the triggering agent and its removal, reduction of aspecific factors that may contribute to the urticaria or can increase the itch, and use of anti-H1 antihistamines (and/or steroids for short periods if antihistamines are not effective). In some instances an anti-H2 antihistamine can be added to the anti-H1 antihistamines, even if the benefits of such practice are not clear. The antileucotriens can be beneficial in a small subgroup of patients with chronic urticaria. In case of chronic urticaria resistant to all the aforementioned treatments, cyclosporine and tacrolimus have been used with good success. When urticaria is associated to anaphylaxis, i.m epinephrine needs to be used, together with antihistamines and steroids (in addition to fluids and bronchodilatators if required).

High intracytoplasmatic levels of Il-4 and Il-5 in a patient with Gleichs syndrome: case report

Gleichs syndrome is characterized by recurrent localized angioedema, hypereosinophilia, elevated levels of IgM, rapid weight gain, itchy urticaria and fever. Little is known about the pathogenesis of this disease. Increased serum levels for IL5, IL6 and C5a have been reported before and during clinical exacerbations. In order to better understand the role of the T cells in Gleichs syndrome we analyzed the intracellular cytokine expression in CD3+ cells of a patient affected by the disease. As hypereosinophilia was documented, we asked whether IL-4 and IL-5 levels were increased, and the intracytoplasmatic expression of these Th2-cytokines was determined. The percentage of T lymphocytes (CD3-gated cells) of both CD8- and CD8+ phenotype expressing different cytokines showed an unusually high percentage of Th2-related cytokine (IL-4, IL-5 and IL-13) expressing T lymphocytes. The two new variants (myeloproliferative and lymphoproliferative) seem to account for hypereosinophilia in patients with hypereosinophilic syndrome (HES). In the lymphroliferative variant, the presence of a clonal CD3-CD4+ Th2 like lymphocyte secreting IL-4 and IL-5 in peripheral blood, may explain the hypereosinophilia and the hyper-IgE. In our study we show that the patient had a lymphoproliferative variant and her T cell had a Th2 type phenotype. Moreover, we suggest that Th2 lymphocytes may play a role in the pathogenesis of Gleichs syndrome. Further studies are needed to evaluate the possibility that a polyclonal aspecific activation of Th2 type cells can lead to hypereosinophilia, IgE production and the other manifestations typical of Gleichs syndrome.

Cross-reactivity between IgE-binding proteins from Anisakis simplex and Dermatophagoides pteronyssinus

An association was found between Anisakis simplex (As) and Dermatophagoides pteronyssinus (Dp) sensitization. One recent study shows a cross-reactivity between As and Dp and tropomyosin (tr)is suspected as being one of the proteins responsible of this cross-reaction. The aim of our study was: 1) to confirm the cross-reactivity between Dp and As; 2) to determine the importance of tr in this cross reaction. SDS-PAGE analysis of Dp and As (metabolic and somatic) extracts was carried out. Then an IgE immunoblotting test using serum from a patient who had specific IgE only to Dp and As and immunoblotting inhibition experiments using Dp extract and tr as inhibitors were performed. We found that patients serum reacted: 1) against larval As antigens with a molecular weight (mw) of 25 kilodalton (kD) and a mw > than 100 kD, 2) against various metabolic As antigens with a mw > than 100 kD, a mw ranging approximately from 35 to 50 kD, and a mw around 20 kD, and 3) against Dp proteins with mw between 35 and 55 kD. Preincubation of patient's serum with Dp extract caused the disappearance of reactivity against antigens with a mw > than 100 kD in both larval and metabolic As extracts and against proteins with mw ranging approximately from 35 to 50 kD in the metabolic As extract. Preincubation of patients serum with As extract caused the disappearance of reactivity against antigens with mw between 35 and 55 kD in the Dp extract. Pre-incubation of patients serum with tr did not induce any change in the immunoblotting profile. The results show that 1) cross-reactive components between Dp and As are some proteins with a mw ranging approximately from 35 to 50 kD and with a mw > than 100 kD, and 2) tr is not involved in cross-reactivity between As and Dp.

Characterization of a novel PMA-inducible pathway of interleukin-13 gene expression in T cells

Although interleukin 13 (IL-13) is an important mediator of asthma and allergic diseases, the molecular mechanisms regulating IL-13 gene expression are not well understood. This study was designed to define the molecular mechanisms governing IL-13 gene expression in T cells. IL-13 expression was examined in human peripheral blood T cells and in the EL-4 T-cell line by enzyme-linked immunosorbent assay and reverse-transcription polymerase chain reaction. An IL-13 promoter deletion analysis was performed using luciferase-based reporter plasmids transiently transfected into EL-4 cells by electroporation. DNA binding factors were investigated using electrophoretic mobility shift assays. In contrast to IL-4 expression, which required concomitant activation of calcium- and protein kinase C- (PKC-) dependent signalling pathways, PKC activation alone was sufficient for IL-13 protein secretion in mitogen-primed (but not resting) peripheral blood T cells, and for IL-13 mRNA expression and promoter activity in EL-4 T cells. Promoter deletion analysis localized a phorbol 12-myristate 13-acetate (PMA)-sensitive element to a proximal promoter region between -109 and -79 base pairs upstream from the IL-13 transcription start site. This promoter region supported the binding of both constitutive and PMA-inducible nuclear factors in gel shift assays.

Visceral larva migrans associated with earthworm ingestion: clinical evolution in an adolescent patient

A 16-year-old girl developed a cough, hypereosinophilia (absolute eosinophil count: 32000/mm3), hypergammaglobulinemia, and multiple noncavitary pulmonary nodules 1 month after having ingested an earthworm on a dare. Spirometry revealed moderate restriction and reduced gas diffusion. Parabronchial biopsy demonstrated eosinophilic organizing pneumonitis with multiple eosinophilic microabscesses, and Toxocara titers were elevated (>1:4096). Ophthalmologic examination ruled out ocular larva migrans. The patient received a 10-day course of albendazole (400 mg orally twice daily) and demonstrated significant clinical improvement with resolution of cough and pulmonary function abnormalities. Her white blood cell count and hypergammaglobulinemia normalized within 20 days, yet eosinophils (absolute eosinophil count: 1780/mm3) and Toxocara serologies (>1:4096) remained elevated 3 months after completing antihelminthic therapy. In this instance, the ingested earthworm served as the paratenic carrier of Toxocara larvae from the soil to the patient. This case highlights the clinical evolution of pulmonary visceral larva migrans infection caused by Toxocara spp. associated with a discrete ingestion in an adolescent patient. In addition, it provides a rare opportunity to define the incubation period of visceral larva migrans and emphasizes the importance of education regarding sources of Toxocara infection.