Side effects and their impact on the success of milk oral immunotherapy (OIT) in children

Oral immunotherapy (OIT) has been introduced as a new immune-modulating treatment under investigation for food allergies. The aim of our study was to evaluate the success of OIT in a cohort of children with milk allergy. These children underwent OIT in a clinical practice and were followed for up to ten years. The secondary endpoint was to describe the main adverse events during OIT and compare them to those reported in the literature.

Eighty-two milk-allergic children started OIT. According to the OIT endpoint reached after one year, all of the children enrolled in the study were divided into four groups: complete desensitization; partial desensitization; step down; and stop groups. Any adverse events that occurred during OIT were also recorded.

Of the 82 patients, eight were recruited in the last months of 2010 so they were still ongoing at the end of the study. For that reason, they were excluded from the analysis. The majority (73%) of the 74 children evaluated (51 boys, 23 girls; median age, 7 years; age range, 2–18 years; specific serum IgE for cow’s milk, 36 KUA/L [range, 3–100 KUA/L]; milk SPT wheal diameter, 7 mm [range, 2–15 mm]) reached complete (58.1%) or partial (14.9%) desensitization, 9.4% were subjected to step down. The remaining 17.6% of the children discontinued OIT because of the occurrence of chronic gastroenteric (GE) symptoms (46.1%) or acute asthma (15.3%) following milk intake.

In agreement with the literature, we found that chronic GE symptoms was the main reason for OIT discontinuation. OIT represents a valid tool for the treatment of food allergies in children; however, the risk of potential adverse reactions, both IgE- and non-IgE-mediated, should be discussed with parents prior to the initiation of OIT.

Eosinophilic Esophagitis: A Comprehensive Review

Eosinophilic esophagitis (EoE) is an emerging chronic atopic clinical-pathologic disease with an estimated prevalence of 1/1000 similar to the one of Crohn's diseases. Usually, EoE is firstly suspected due to symptoms that are caused by esophageal dysfunction and/or fibrosis. EoE diagnosis is confirmed if the esophageal biopsy shows at least 15 eosinophils per high power field (eos/hpf) as a peak value in one or more of at least four specimens obtained randomly from the esophagus. Most of the patients affected by EoE have other atopic diseases such as allergic rhinitis, asthma, IgE-mediated food allergies, and/or atopic dermatitis. The local inflammation is a T helper type 2 (Th2) flogosis, which most likely is driven by a mixed IgE and non-IgE-mediated reaction to food and/or environmental allergens. Recently published genetic studies showed also that EoE is associated with single nucleotide polymorphism (SNP) on genes which are important in atopic inflammation such as thymic stromal lymphopoietin (TSLP) located close to the Th2 cytokine cluster (IL-4, IL-5, IL-13) on chromosome 5q22. When the EoE diagnosis is made, it is imperative to control the local eosinophilic inflammation not only to give symptomatic relief to the patient but also to prevent complications such as esophageal stricture and food impaction. EoE is treated like many other atopic diseases with a combination of topical steroids and/or food antigen avoidance.

Omalizumab facilitates rapid oral desensitization for peanut allergy

BACKGROUND

Peanut oral immunotherapy is a promising approach to peanut allergy, but reactions are frequent, and some patients cannot be desensitized. The anti-IgE medication omalizumab (Xolair; Genentech, South San Francisco, Calif) might allow more rapid peanut updosing and decrease reactions.

OBJECTIVE

We sought to evaluate whether omalizumab facilitated rapid peanut desensitization in highly allergic patients.

METHODS

Thirty-seven subjects were randomized to omalizumab (n = 29) or placebo (n = 8). After 12 weeks of treatment, subjects underwent a rapid 1-day desensitization of up to 250 mg of peanut protein, followed by weekly increases up to 2000 mg. Omalizumab was then discontinued, and subjects continued on 2000 mg of peanut protein. Subjects underwent an open challenge to 4000 mg of peanut protein 12 weeks after stopping study drug. If tolerated, subjects continued on 4000 mg of peanut protein daily.

RESULTS

The median peanut dose tolerated on the initial desensitization day was 250 mg for omalizumab-treated subjects versus 22.5 mg for placebo-treated subject. Subsequently, 23 (79%) of 29 subjects randomized to omalizumab tolerated 2000 mg of peanut protein 6 weeks after stopping omalizumab versus 1 (12%) of 8 receiving placebo (P < .01). Twenty-three subjects receiving omalizumab versus 1 subject receiving placebo passed the 4000-mg food challenge. Overall reaction rates were not significantly lower in omalizumab-treated versus placebo-treated subjects (odds ratio, 0.57; P = .15), although omalizumab-treated subjects were exposed to much higher peanut doses.

CONCLUSION

Omalizumab allows subjects with peanut allergy to be rapidly desensitized over as little as 8 weeks of peanut oral immunotherapy. In the majority of subjects, this desensitization is sustained after omalizumab is discontinued. Additional studies will help clarify which patients would benefit most from this approach.

Eosinophilic esophagitis is characterized by a non-IgE-mediated food hypersensitivity

Eosinophilic esophagitis (EoE) is a chronic disease characterized clinically by symptoms of esophageal dysfunction and histologically by eosinophil-predominant inflammation. EoE is frequently associated with concomitant atopic diseases and immunoglobulin E (IgE) sensitization to food allergens in children as well as to aeroallergens and cross-reactive plant allergen components in adults. Patients with EoE respond well to elemental and empirical food elimination diets. Recent research has, however, indicated that the pathogenesis of EoE is distinct from IgE-mediated food allergy. In this review, we discuss the individual roles of epithelial barrier defects, dysregulated innate and adaptive immune responses, and of microbiota in the pathogenesis of EoE. Although food has been recognized as a trigger factor of EoE, the mechanism by which it initiates or facilitates eosinophilic inflammation appears to be largely independent of IgE and needs to be further investigated. Understanding the pathogenic role of food in EoE is a prerequisite for the development of specific diagnostic tools and targeted therapeutic procedures.

Wheat allergy: diagnosis and management

Triticum aestivum (bread wheat) is the most widely grown crop worldwide. In genetically predisposed individuals, wheat can cause specific immune responses. A food allergy to wheat is characterized by T helper type 2 activation which can result in immunoglobulin E (IgE) and non-IgE mediated reactions. IgE mediated reactions are immediate, are characterized by the presence of wheat-specific IgE antibodies, and can be life-threatening. Non-IgE mediated reactions are characterized by chronic eosinophilic and lymphocytic infiltration of the gastrointestinal tract. IgE mediated responses to wheat can be related to wheat ingestion (food allergy) or wheat inhalation (respiratory allergy). A food allergy to wheat is more common in children and can be associated with a severe reaction such as anaphylaxis and wheat-dependent, exercise-induced anaphylaxis. An inhalation induced IgE mediated wheat allergy can cause baker’s asthma or rhinitis, which are common occupational diseases in workers who have significant repetitive exposure to wheat flour, such as bakers. Non-IgE mediated food allergy reactions to wheat are mainly eosinophilic esophagitis (EoE) or eosinophilic gastritis (EG), which are both characterized by chronic eosinophilic inflammation. EG is a systemic disease, and is associated with severe inflammation that requires oral steroids to resolve. EoE is a less severe disease, which can lead to complications in feeding intolerance and fibrosis. In both EoE and EG, wheat allergy diagnosis is based on both an elimination diet preceded by a tissue biopsy obtained by esophagogastroduodenoscopy in order to show the effectiveness of the diet. Diagnosis of IgE mediated wheat allergy is based on the medical history, the detection of specific IgE to wheat, and oral food challenges. Currently, the main treatment of a wheat allergy is based on avoidance of wheat altogether. However, in the near future immunotherapy may represent a valid way to treat IgE mediated reactions to wheat.

Eosinophilic Esophagitis and Gastroenteritis

Eosinophilic gastrointestinal disease (EGID) can be classified as eosinophilic esophagitis (EoE) when the eosinophilia is limited to the esophagus or as eosinophilic gastritis (EG) if it is limited to the gastric tract, eosinophilic colitis (EC) if it is limited to the colon, and eosinophilic gastroenteritis (EGE) if the eosinophilia involves one or more parts of the gastrointestinal tract. EoE is by far the most common EGID. It is a well-defined chronic atopic disease due to a T helper type 2 (Th2) inflammation triggered often by food allergens. EoE diagnosis is done if an esophageal biopsy shows at least 15 eosinophils per high power field (eos/hpf). Globally accepted long-term therapies for EoE are the use of swallowed inhaled steroids or food antigen avoidance. The treatment of EoE is done not only to control symptoms but also to prevent complications such as esophageal stricture and food impaction. EGE cause non-specific gastrointestinal (GI) symptoms and are diagnosed if esophagogastroduodenoscopy (EGD)/colonoscopy show eosinophilia in one or more parts of the GI tract. They are rare diseases with an unclear pathogenesis, and they are poorly defined in terms of diagnostic criteria and treatment. Before initiating treatment of any EGE, it is imperative to conduct a differential diagnosis to exclude other causes of hypereosinophilia with GI localization. EGE are often poorly responsive to therapy and there is no commonly accepted long-term treatment. EG has many characteristics similar to EoE, including the fact that it is often due to a food allergen-driven Th2 inflammation; transcriptome analysis however shows that it is more a systemic disease and has a different gene signature than EoE. EC is a benign form of delayed food allergy in infant and is instead a difficult-to-treat severe inflammatory condition in older children and adults. EC in the latter groups can be a manifestation of drug allergy or autoimmune disease. Overall EGE, EC, and EG are rare and are a diagnosis of exclusion until more common causes of eosinophilia have been excluded.

Egg Food Challenges are Associated with More Gastrointestinal Reactions

Egg allergy is a common pediatric allergy, and is usually outgrown by elementary school age. There is, therefore, a need to perform an oral food challenge (OFC) to establish the presence of food allergy to egg. In this study, we conducted a retrospective review of 2304 OFCs at a pediatric center and analyzed the severity of reactions during egg OFCs and compared them with other foods. The gastrointestinal system (GI) has been reported as more affected in egg food challenge. This study confirmed that 11% of patients undergoing egg OFC had GI symptoms vs. 7% undergoing food challenges for other foods or compared to milk, peanut and tree nut, individually. However, the involvement of lower respiratory tract was less frequent with egg than observed in peanut and tree nut OFC and similar to observed rate in milk. In conclusion, our study confirmed that OFC to egg causes more GI symptoms and less respiratory symptoms compared to other foods, in particular peanuts and tree nuts. However, 27% of children who failed egg OFC had lower respiratory tract reactions and required the use of epinephrine, similarly to children undergoing milk challenge.

Seasonal exacerbation of esophageal eosinophilia in children with eosinophilic esophagitis and allergic rhinitis

BACKGROUND

Evidence supports a possible link between eosinophilic esophagitis (EoE) and environmental aeroallergens, which can manifest as seasonal exacerbation of esophageal eosinophilia. Few studies have examined this link in pediatric patients with EoE.

OBJECTIVE

To identify the proportion of patients with seasonal induced esophageal eosinophilia.

METHODS

A retrospective chart review was conducted of all patients diagnosed with EoE at the authors' institution. Demographic data were collected by chart review. Seasonal variation or flare was defined as a change from fewer than to at least 15 eosinophils per high-power field and a minimum of a 2-fold increase in eosinophil count between 2 consecutive biopsy specimens in different seasons without dietary or medication modifications.

RESULTS

Of the 1,180 patients with EoE, 160 (14%) were suspected of having aeroallergen-associated triggers by history. Of these 160 patients, 32 (20%) had biopsy examination-confirmed variation of EoE triggered by aeroallergens. Most of these patients were boys (84%), all had a history or examination consistent with allergic rhinitis, and most had a history of asthma (75%). Thirty-two subjects had obvious seasonal variation, 22 of whom also had known food-induced symptoms.

CONCLUSION

Children with EoE and allergic rhinitis might have exacerbations in their esophageal eosinophilia during certain seasons depending on the specific aeroallergens to which they are sensitized. Identification of environmental allergens to sensitized patients is important and can guide therapy.

The importance of TSLP in allergic disease and its role as a potential therapeutic target

Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine similar to IL- 7, whose gene is located on chromosome 5q22.1 and it exerts its biological function through the TSLP-Receptor (TSLP-R). TSLP is expressed primarily by epithelial cells at barrier surfaces such as the skin, gut and lung in response to danger signals. Since it was cloned in 1994, there has been accumulating evidence that TSLP is crucial for the maturation of antigen presenting cells and hematopoietic cells. TSLP genetic variants and its dysregulated expression have been linked to atopic diseases such as atopic dermatitis, asthma, allergic rhinitis and eosinophilic esophagitis.

Immunotherapeutic approaches for the treatment of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a clinical pathologic disease characterized by symptoms of esophageal dysfunction and eosinophilia of the esophagus. When the diagnosis is confirmed, it is important to treat the eosinophilic inflammation not only to control the presenting symptoms, but also to prevent acute and chronic complications. The pathogenesis of EoE is most likely a mixed IgE and non-IgE food-mediated reaction, where Th2 cytokines drive esophageal eosinophilia as in other atopic diseases. Hence, it is not surprising that therapy is based on inflammation control, with steroids (oral or topical) and/or food antigen avoidance. However, these treatment options are not specific, reduce the quality of life of patients and have significant side effects, therefore, there is an ongoing effort to design more specific immunotherapies. In this review, we review standard and immunotherapeutic options for EoE treatment, such as anti-IL-5, anti-TNFα, anti-IgE, anti-CRTH, oral allergy desensitization and environmental immunotherapy.

Amoxicillin allergy in children: five-day drug provocation test in the diagnosis of nonimmediate reactions

BACKGROUND

The drug provocation test (DPT) is the gold standard to rule out drug hypersensitivity. There are standardized DPT protocols to diagnose immediate reactions to drugs, but not for nonimmediate reactions.

OBJECTIVE

The aim of this study was to show the sensitivity and specificity of an allergy work-up that included a 5-day DPT in children with histories of nonimmediate reactions to amoxicillin through focusing on a pediatric population with histories of immediate and nonimmediate reactions to amoxicillin.

METHODS

Two hundred consecutive patients with histories of amoxicillin reactions referred to the Allergy Unit of Anna Meyer Children's Hospital for suspected drug allergy from 2008 to 2011 underwent in vivo tests with the culprit drug according to European Academy of Allergy and Clinical Immunology guidelines. Moreover, most of those children, regardless of the skin tests results, were challenged with amoxicillin for a total of 5 days.

RESULTS

In 4 years, 200 patients were evaluated for a history of drug hypersensitivity to amoxicillin. The majority of patients (76%) had a history of mild nonimmediate reactions. All 200 patients underwent skin tests, and 9 of 200 tested positive. A total of 177 DPTs were performed with amoxicillin for 5 days in each child. Diagnosis of amoxicillin allergy was confirmed by a DPT in 17 patients (9.6%); 14/17 had history of nonimmediate reactions; 4/14 (26.6%) reacted on day 5.

CONCLUSION

According to our results, a long-term DPT protocol increases the sensitivity of the allergy work-up, and it should be recommended for patients with a history of amoxicillin nonimmediate reaction.

Azithromycin is more allergenic than clarithromycin in children with suspected hypersensitivity reaction to macrolides

BACKGROUND

Macrolides are considered safe antibiotics with reduced allergenic activity. However, studies on the safety of macrolides are scarce, particularly in children.

OBJECTIVE

The aim of this study was to assess the frequency of hypersensitivity reactions to clarithromycin and azithromycin in a group of children referred to our allergy unit for suspected macrolide allergy.

METHODS

We retrospectively reviewed the charts of 90 children aged 1-17 years with symptoms suggestive of hypersensitivity reaction to clarithromycin or azithromycin between December 31, 2008 and December 31, 2013. The allergy workup included skin tests (ie, skin prick tests and/or intradermal tests), determination of serum specific IgE (sIgE) to clarithromycin and azithromycin, and, if necessary to reach a diagnosis, oral provocation tests.

RESULTS

Seventy-seven children completed the allergy workup. A reaction to clarithromycin was recorded in 58 children (75.3%): 21 (36.2%) had a history of immediate reactions, and 37 (63.8%) had a history of nonimmediate reactions. A reaction to azithromycin was recorded in 19 children (24.6%): 6 (31.5%) had a history of immediate reaction, and 13 (68.42%) had a history of nonimmediate reaction. Positive results in skin tests and oral provocation tests with the suspect drug confirmed the diagnosis in 15.5% of reactions to clarithromycin (9 of 58) and in 47.3% of reactions to azithromycin (9 of 19) (P = .004).

CONCLUSION

A complete allergy workup enabled us to confirm a diagnosis of clarithromycin and azithromycin allergy in 15.5% and 47.3% of cases, respectively. Azithromycin was more allergenic than clarithromycin in children.

Recent advances in the pathological understanding of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergen-mediated inflammatory disease of the esophagus. This inflammation leads to feeding difficulties, failure to thrive and vomiting in young children, and causes food impaction and esophageal stricture in adolescents and adults. In the 20 years since EoE was first described, we have gained a great deal of knowledge regarding the genetic predisposition of disease, the inflammatory milieu associated with EoE and the long-term complications of chronic inflammation. Herein, we summarize the important breakthroughs in the field including both in vitro and in vivo analysis. We discuss insights that we have gained from large-scale unbiased genetic analysis, a multitude of genetically and chemically altered mouse models of EoE and most importantly, the results of clinical trials of various pharmacologic agents. Understanding these successes and failures may be the key to developing more effective therapeutic strategies.

GWAS identifies four novel eosinophilic esophagitis loci

Eosinophilic esophagitis (EoE) is an allergic disorder characterized by infiltration of the oesophagus with eosinophils. We had previously reported association of the TSLP/WDR36 locus with EoE. Here we report genome-wide significant associations at four additional loci; c11orf30 and STAT6, which have been previously associated with both atopic and autoimmune diseases, and two EoE-specific loci, ANKRD27 that regulates the trafficking of melanogenic enzymes to epidermal melanocytes and CAPN14, that encodes a calpain whose expression is highly enriched in the oesophagus. The identification of five EoE loci, not only expands our aetiological understanding of the disease but may also represent new therapeutic targets to treat the most debilitating aspect of EoE, oesophageal inflammation and remodelling.

Food allergy

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 the future.

Invariant natural killer T cells in children with eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is an atopic disease characterized by eosinophilic inflammation in which dietary antigens (in particular, milk) play a major role. EoE is most likely a mixed IgE and non-IgE food-mediated reaction in which overexpression of Th2 cytokines, particularly IL-13, play a major role; however, the cells responsible for IL-13 overexpression remain elusive. Th2-cytokines are secreted following the ligation of invariant natural killer T cell receptors to sphingolipids (SLs). Sphingolipids (SLs) are presented via the CD1d molecule on the INKTs surface. Cow's milk-derived SL has been shown to activate iNKTs from children with IgE-mediated food allergies to milk (FA-MA) to produce Th2 cytokines. The role of iNKTs and milk-SL in EoE pathogenesis is currently unknown.

OBJECTIVE

The aim of this study was to investigate the role of iNKTs and milk-SL in EoE.

METHODS

Peripheral blood mononuclear cells (PBMCs) from 10 children with active EoE (EoE-A), 10 children with controlled EoE (EoE-C) and 16 healthy controls (non-EoE) were measured ex vivo and then incubated with α-galactosylceramide (αGal) and milk-SL. INKTs from peripheral blood (PB) and oesophageal biopsies were studied.

RESULTS

EoE-A children had significantly fewer peripheral blood iNKTs with a greater Th2-response to αGal and milk-SM compared with iNKTs of EoE-C and non-EoE children. Additionally, EoE-A children had increased iNKT levels in oesophageal biopsies compared with EoE-C children.

CONCLUSION

Milk-SLs are able to activate peripheral blood iNKTs in EoE-A children to produce Th2 cytokines. Additionally, iNKT levels are higher at the site of active oesophageal eosinophilic inflammation.

CLINICAL RELEVANCE

This study suggests that sphingolipids (SLs) contained in milk may drive the development of EoE by promoting an iNKT-cell-mediated Th2-type cytokine response that facilitates eosinophil-mediated allergic inflammation.

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.