Mechanisms of immune tolerance relevant to food allergy

Glycosylation-modified antigens as a tolerance-inducing vaccine platform prevent anaphylaxis in a pre-clinical model of food allergy

The only FDA-approved oral immunotherapy for a food allergy provides protection against accidental exposure to peanuts. However, this therapy often causes discomfort or side effects and requires long-term commitment. Better preventive and therapeutic solutions are urgently needed. We develop a tolerance-inducing vaccine technology that utilizes glycosylation-modified antigens to induce antigen-specific non-responsiveness. The glycosylation-modified antigens are administered intravenously (i.v.) or subcutaneously (s.c.) and traffic to the liver or lymph nodes, respectively, leading to preferential internalization by antigen-presenting cells, educating the immune system to respond in an innocuous way. In a mouse model of cow's milk allergy, treatment with glycosylation-modified β-lactoglobulin (BLG) is effective in preventing the onset of allergy. In addition, s.c. administration of glycosylation-modified BLG shows superior safety and potential in treating existing allergies in combination with anti-CD20 co-therapy. This platform provides an antigen-specific immunomodulatory strategy to prevent and treat food allergies.

Effects of Early Diet on the Prevalence of Allergic Disease in Children: A Systematic Review and Meta-Analysis

Recent evidence suggests that the timing of introduction, types, and amounts of complementary foods/allergenic foods may influence the risk of allergic disease. However, the evidence has not been updated and comprehensively synthesized. The Cochrane Library, EMBASE, Web of Science, and PubMed databases were searched from the inception of each database up to 31 May 2023 (articles prior to 2000 were excluded manually). Statistical analyses were performed using RevMan 5. The GRADE approach was followed to rate the certainty of evidence. Compared with >6 mo, early introduction of eggs (≤6 mo of age) might reduce the risk of food allergies in preschoolers aged <6 y (odds ratio [OR], 0.65; 95% confidence interval [CI], 0.53, 0.81), but had no effect on asthma or atopic dermatitis (AD). Consumption of fish at 6-12 mo might reduce the risk of asthma in children (aged 5-17 y) compared with late introduction after 12 mo (OR, 0.61; 95% CI: 0.52, 0.72). Introduction of allergenic foods for ≤6 mo of age, compared with >6 mos, was a protective factor for the future risk (children aged ≤10 y) of AD (OR, 0.93; 95% CI: 0.89, 0.97). Probiotic intervention for infants at high risk of allergic disease significantly reduced the risk of food allergy at ages 0-3 y (OR, 0.72; 95% CI: 0.56, 0.94), asthma at 6-12 y (OR, 0.61; 95% CI: 0.41, 0.90), and AD at aged <6 y (3-6 y: OR, 0.70; 95% CI: 0.52, 0.94; 0-3 y: OR, 0.73; 95% CI: 0.59, 0.91). Early introduction of complementary foods or the high-dose vitamin D supplementation in infancy was not associated with the risk of developing food allergies, asthma, or AD during childhood. Early introduction to potential allergen foods for normal infants or probiotics for infants at high risk of allergies may protect against development of allergic disease. This study was registered at PROSPERO as CRD42022379264.

Recent advances in selective allergies to mammalian milk proteins not associated with Cow's Milk Proteins Allergy

Cow's milk proteins allergy (CMA) is an atypical immune system response to cow's milk and dairy products. It's one of the most common food allergies in children affecting 8% of the total pediatric population pediatric population. This comprehensive review examines recent studies in CMA, especially regarding mammalian milk allergies such as goat's, sheep's, buffalo's, camel's, mare's and donkey's milk allergies in order to increase awareness of these selective allergies and to reduce allergy risks for those who have them. The consumption of other mammalian milk types is not recommended because of the significant homology between milk proteins from cow, sheep, goat and buffalo resulting in clinical cross-reactivity. However, camel's, mare's or donkey's milk may be tolerated by some allergic patients. Selective mammalian milk allergies are unusual and rare disorders characterized by severe symptoms including angio-oedema, urticaria, respiratory manifestations and anaphylaxis. Based on the reported allergic cases, cheese products including Ricotta, Romano, Pecorino and Mozzarella, are considered as the most common source of allergens especially in goat's, sheep's and buffalo's milk allergies, while the major allergens in donkey's and mare's milk seems to be whey proteins including lysozyme, α-lactalbumin and β-lactogloblin due to the low casein/whey proteins ratio in equine's milk.

Molecular Mechanism and Clinical Effects of Probiotics in the Management of Cow's Milk Protein Allergy

Cow's milk protein allergy (CMPA) is the most common food allergy (FA) in infancy, affecting approximately 2% of children under 4 years of age. According to recent studies, the increasing prevalence of FAs can be associated with changes in composition and function of gut microbiota or "dysbiosis". Gut microbiota regulation, mediated by probiotics, may modulate the systemic inflammatory and immune responses, influencing the development of allergies, with possible clinical benefits. This narrative review collects the actual evidence of probiotics' efficacy in the management of pediatric CMPA, with a specific focus on the molecular mechanisms of action. Most studies included in this review have shown a beneficial effect of probiotics in CMPA patients, especially in terms of achieving tolerance and improving symptoms.

Emerging drugs for the treatment of type 1 diabetes mellitus: a review of phase 2 clinical trials

INTRODUCTION

Despite therapeutic advances in the field of diabetes management since the discovery of insulin 100 years ago, there are still unmet clinical needs for people with type 1 diabetes mellitus (T1DM).

AREAS COVERED

Genetic testing and islet autoantibodies testing allow researchers to design prevention studies. This review discusses the emerging therapy for prevention of T1DM, disease modification therapy in early course of T1DM, and therapies and technologies for established T1DM. We focus on phase 2 clinical trials with promising results, thus avoiding the exhausted list of every new therapy for T1DM.

EXPERT OPINION

Teplizumab has demonstrated potential as a preventative agent for individuals at risk prior to the onset of overt dysglycemia. However, these agents are not without side effects, and there are uncertainties on long-term safety. Technological advances have led a substantial influence on quality of life of people suffering from T1DM. There remains variation in uptake of new technologies across the globe. Novel insulins (ultra-long acting), oral insulin, and inhaled insulin attempt to narrow the gap of unmet needs. Islet cell transplant is another exciting field, and stem cell therapy might have potential to provide unlimited supply of islet cells.

Oral Tolerance Induction-Opportunities and Mechanisms

Oral tolerance is the active absence of response to food allergens, which involves complex mechanisms in the gut-associated lymphoid tissue. Food allergy results from the disruption of such tolerance or the absence of its establishment in the first place. It follows allergic sensitization with the production of allergen-specific IgE and results from the degranulation of basophils and mast cells on subsequent exposure to the allergen. Oral tolerance induction has been explored in the contexts of prevention and treatment of food allergy. Early introduction of allergenic foods (i.e., egg and peanut) in the diet of infants, before allergic sensitization occurs (i.e., via inflamed skin affected with eczema) has shown to be beneficial. Guidelines have changed to recommend the introduction of these allergenic foods by 6 months of age. For food allergic individuals, oral tolerance induction has been attempted using allergen-specific immunotherapy, which involves the administration of an allergen, modified or not, through various possible routes, including oral, sublingual, epicutaneous, and subcutaneous, with or without concomitant administration of antibody-based biologics. Further research into the immune mechanisms of food allergy and oral tolerance can lead to the identification of novel targets to suppress the food allergic response and reverse the current food allergy epidemic.

Efficacy of diet on fatigue, quality of life and disability status in multiple sclerosis patients: rapid review and meta-analysis of randomized controlled trials

Background

Multiple sclerosis is an inflammatory and neurodegenerative disease. People with multiple sclerosis (pwMS) experience chronic fatigue which is difficult to deal with therapeutically and greatly affects health-related quality of life (QOL).

PwMS are aware of the lack of generalized dietary advice related to their disease, leading to self-experimentation with diet.

It is necessary to provide objective information about dietary interventions for pwMS. We aim to provide an objective synthesis of the evidence for efficacy and safety of specific diets in pwMS through a rapid review and meta-analyses of randomized controlled trials (RCTs), examining symptomatic fatigue (MFIS), QOL, Expanded-Disability-Status-Scale (EDSS), and severe adverse events.

Methods

We have carried out a rapid review (MEDLINE and EMBASE) up to December 2021, with PRISMA methodology, and meta-analyses, of (RCTs). All statistical analyses were performed using the comprehensive meta-analysis (CMA) -RStudio 4.1.3. The analysis used weighted mean differences (WMD) and a 95% confidence interval (CI) using a random-effects model to compare the effects of the dietary intervention with the control.

Results

Eight studies met the inclusion criteria. Of these eight studies, five analyzed EDSS, three MFIS, and three QOL. A total of 515 patients were analyzed. These meta-analyses cumulative evidence support that dietary intervention is associated with a trend of reduction in fatigue (308 patients studied) -the difference between means (SMD) of the control group and intervention group was -2,033, 95%-IC (-3,195, -0,152), a p-value of 0.0341)-, an increase in QOL (77 patients studied), no significant effect on EDSS (337 patients studied), and no severe adverse events.

Conclusions

It is difficult to reach a high level of evidence in dietary studies. Our findings show that dietary intervention is associated with a trend of reduction in fatigue in MS. Taking into account the potential of dietary interventions and the benefit/risk ratio in their favor, neurologists must be aware of the great importance of making interventions on diet in MS if necessary. There are dietary interventions with some evidence of benefit for patients with MS, which could be chosen based on adherence, patient preferences, and individual outcomes. Large prospective clinical trials are needed to shed further light on this topic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02913-w.

Oropharyngeal symptoms without systemic reactions as a risk factor for food allergen intolerance: a longitudinal pediatric study

Background

The determinants of tolerance to food allergens are not fully understood. We aimed to elucidate the longitudinal association between oropharyngeal symptoms without systemic reactions (OSw/oS) and tolerance to food allergens.

Methods

We included all patients diagnosed with single food allergy to egg (n = 121), milk (n = 55), and wheat (n = 41) using the oral food challenge test (OFC) from 2014 to 2017. These patients received oral immunotherapy at home and/or in the hospital after diagnosis by OFC. We compared the incidence proportion of tolerance within 2 years by OSw/oS and other variables for 217 patients with food allergy. We defined OSw/oS as isolated symptoms of oropharyngeal discomfort that occurred after ingestion of a safe dose of the allergenic food determined by the OFC in the first 6 months.

Results

Of the 217 patients (median age 37.5 months, male 64.5%), 53 developed OSw/oS (24.4%), and 151 (egg, 85 milk, 36 and wheat, 30) attained tolerance in 2 years. Patients without OSw/oS showed a significantly higher incidence of tolerance than those with the symptoms (crude hazard ratio [HR] 5.62, 95% confidence interval [CI] 3.58–8.82, p < 0.001). The association was consistently significant in the multivariable model (adjusted HR 9.50, 95% CI 5.25–17.20, p < 0.001) independent of other risk factors for intolerance, such as concomitant bronchial asthma (adjusted HR 3.33), history of anaphylaxis (adjusted HR 2.16), milk allergy (adjusted HR 2.02), and allergic symptoms with low dose OFC (adjusted HR 1.52).

Conclusion

Our results suggest that OSw/oS may be a risk factor for intolerance to food allergens. To reveal a high risk of food allergen intolerance may help patients and their families as well as healthcare professionals prepare for the challenge of continuing oral immunotherapy.

Immune responses in the irritable bowel syndromes: time to consider the small intestine

BACKGROUND

Irritable bowel syndrome (IBS) is considered a disorder of gut-brain interaction (DGBI), presenting as chronic abdominal pain and altered defaecation. Symptoms are often food related. Much work in the field has focused on identifying physiological, immune and microbial abnormalities in the colon of patients; however, evidence of small intestinal immune activation and microbial imbalance has been reported in small studies. The significance of such findings has been largely underappreciated despite a growing body of work implicating small intestinal homeostatic imbalance in the pathogenesis of DGBIs.

MAIN TEXT

Small intestinal mechanosensation is a characteristic feature of IBS. Furthermore, altered small intestinal barrier functions have been demonstrated in IBS patients with the diarrhoea-predominant subtype. Small intestinal bacterial overgrowth and increased populations of small intestinal mast cells are frequently associated with IBS, implicating microbial imbalance and low-grade inflammation in the pathogenesis of IBS. Furthermore, reports of localised food hypersensitivity responses in IBS patients implicate the small intestine as the site of immune-microbial-food interactions.

CONCLUSIONS

Given the association of IBS symptoms with food intake in a large proportion of patients and the emerging evidence of immune activation in these patients, the current literature suggests the pathogenesis of IBS is not limited to the colon but rather may involve dysfunction of the entire intestinal tract. It remains unclear if regional variation in IBS pathology explains the various symptom phenotypes and further work should consider the intestinal tract as a whole to answer this question.

Understanding Nanomaterial-Liver Interactions to Facilitate the Development of Safer Nanoapplications

Nanomaterials (NMs) are widely used in commercial and medical products, such as cosmetics, vaccines, and drug carriers. Exposure to NMs via various routes such as dermal, inhalation, and ingestion has been shown to gain access to the systemic circulation, resulting in the accumulation of NMs in the liver. The unique organ structures and blood flow features facilitate the liver sequestration of NMs, which may cause adverse effects in the liver. Currently, most in vivo studies are focused on NMs accumulation at the organ level and evaluation of the gross changes in liver structure and functions, however, cell-type-specific uptake and responses, as well as the molecular mechanisms at cellular levels leading to effects at organ levels are lagging. Herein, the authors systematically review diverse interactions of NMs with the liver, specifically on major liver cell types including Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs), hepatic stellate cells (HSCs), and hepatocytes as well as the detailed molecular mechanisms involved. In addition, the knowledge gained on nano-liver interactions that can facilitate the development of safer nanoproducts and nanomedicine is also reviewed.

Use of a Liver-targeting Nanoparticle Platform to Intervene in Peanut-induced anaphylaxis through delivery of an Ara h2 T-cell Epitope

To address the urgent need for safe food allergen immunotherapy, we have developed a liver-targeting nanoparticle platform, capable of intervening in allergic inflammation, mast cell release and anaphylaxis through the generation of regulatory T-cells (Treg). In this communication, we demonstrate the use of a poly (lactide-co-glycolide acid) (PLGA) nanoparticle platform for intervening in peanut anaphylaxis through the encapsulation and delivery of a dominant protein allergen, Ara h 2 and representative T-cell epitopes, to liver sinusoidal endothelial cells (LSECs). These cells have the capacity to act as natural tolerogenic antigen-presenting cells (APC), capable of Treg generation by T-cell epitope presentation by histocompatibility (MHC) type II complexes on the LSEC surface. This allowed us to address the hypothesis that the tolerogenic nanoparticles platform could be used as an effective, safe, and scalable intervention for suppressing anaphylaxis to crude peanut allergen extract. Following the analysis of purified Ara h 2 and representative MHC-II epitopes Treg generation in vivo, a study was carried out to compare the best-performing Ara h 2 T-cell epitope with a purified Ara h 2 allergen, a crude peanut protein extract (CPPE) and a control peptide in an oral sensitization model. Prophylactic as well as post-sensitization administration of the dominant encapsulated Ara h 2 T-cell epitope was more effective than the purified Ara h2 in eliminating anaphylactic manifestations, hypothermia, and mast cell protease release in a frequently used peanut anaphylaxis model. This was accompanied by decreased peanut-specific IgE blood levels and increased TGF-β release in the abdominal cavity. The duration of the prophylactic effect was sustained for two months. These results demonstrate that targeted delivery of carefully selected T-cell epitopes to natural tolerogenic liver APC could serve as an effective platform for the treatment of peanut allergen anaphylaxis.

Oral Immunotherapy in Food Allergy: A Critical Pediatric Perspective

There is evidence that in children with persistent IgE-mediated food allergy (FA) to cow's milk, hen's egg, and peanut, oral allergen-specific immunotherapy (OIT) may increase the reaction threshold to the culprit food allergen(s). OIT may protect patients from the occurrence of severe reactions in case of accidental ingestion of the culprit food during treatment. Notwithstanding, many gaps are still unsolved, including safety issues, identification of predictive biomarkers, and post-desensitization efficacy. In this perspective, the use of omalizumab (Anti-IgE monoclonal antibody) has been proposed as an adjunctive treatment to OIT in order to reduce the risk of allergic reactions related to OIT. This review aims to summarize the current evidence and unmet needs on OIT in children with FA to enhance the development of longitudinal, prospective, and well-designed studies able to fill the current gaps soon.

Characteristics of Exogenous Allergen in Breast Milk and Their Impact on Oral Tolerance Induction

Food allergy is a common health problem in childhood since its prevalence was estimated to range from 6. 5 to 24.6% in European countries. Recently, a lot of research has focused on the impact of breastfeeding on oral tolerance induction. Since it was found that breast milk contains immunologically active food antigens, it would be very helpful to clarify the factors of antigen shedding that promotes oral tolerance. This narrative review aimed to summarize the latest evidence from experimental and human studies regarding allergen characteristics in human milk that may influence oral tolerance induction. A literature search in PubMed, MEDLINE, and Google Scholar was conducted. The diet of the mother was found to have a direct impact on allergen amount in the breastmilk, while antigens had different kinetics in human milk between women and depending on the antigen. The mode of antigen consumption, such as the cooking of an antigen, may also affect the allergenicity of the antigen in human milk. The dose of the antigen in human milk is in the range of nanograms per milliliter; however, it was found to have a tolerogenic effect. Furthermore, the presence of antigen-specific immunoglobulins, forming immune complexes with antigens, was found more tolerogenic compared to free allergens in experimental studies, and this is related to the immune status of the mother. While examining available data, this review highlights gaps in knowledge regarding allergen characteristics that may influence oral tolerance.

Update on the Role of Allergy in Pediatric Functional Abdominal Pain Disorders: A Clinical Perspective

Both functional abdominal pain disorders (FAPDs) and food allergies are relatively common in children and adolescents, and most studies report an association between FAPDs and allergic conditions. FAPDs share pathophysiologic processes with allergies, including both immune and psychological processes interacting with the microbiome. No conclusive data are implicating IgE-mediated reactions to foods in FAPDs; however, there may be patients who have IgE reactions localized to the gastrointestinal mucosa without systemic symptoms that are not identified by common tests. In FAPDs, the data appears stronger for aeroallergens than for foods. It also remains possible that food antigens initiate an IgG reaction that promotes mast cell activation. If a food allergen is identified, the management involves eliminating the specific food from the diet. In the absence of systemic allergic symptoms or oral allergy syndrome, it appears unlikely that allergic triggers for FAPDs can be reliably identified by standard testing. Medications used to blunt allergic reactions or symptomatically treat allergic reactions may be useful in FAPDs. The purpose of the current manuscript is to review the current literature regarding the role of allergy in FAPDs from a clinical perspective, including how allergy may fit in the current model of FAPDs.

Mechanisms of oral immunotherapy

Food allergy presents a significant global health concern with up to 10% of the population affected in developed nations and a steadily increasing prevalence. In many cases, particularly with peanut, tree nut and shellfish, food allergy is a lifelong and potentially life-threatening diagnosis. While no 'cure' for IgE-mediated food allergy exists, oral immunotherapy (OIT) is a promising treatment modality with the peanut OIT drug Palforzia (Aimmune Therapeutics) the only treatment for food allergy that is currently approved by the United States Food and Drug Administration. OIT primarily induces a state of desensitization with only a minority of subjects achieving sustained unresponsiveness, a state of limited clinical remission that appears to be immunologically distinct from natural tolerance. Early humoural changes during OIT include an initial increase in allergen-specific IgE, which eventually decreases to below baseline levels as OIT progresses, and a gradual increase in allergen-specific IgA and IgG4 that continues throughout the course of OIT. Basophil hyporesponsiveness and decreased skin prick test wheal size are observed within the first year of OIT, and persistence after completion of therapy has been associated with sustained unresponsiveness. In the T-cell compartment, there is an initial expansion followed by a decline in the number and activity of T helper 2 (TH 2) cells, the latter of which may be dependent on an expansion of IL-10-producing cells, including regulatory T-cells. Our understanding of the immunomodulatory effects of OIT continues to evolve, with new technologies such as single-cell transcriptional profiling and antibody epitope analysis allowing for more detailed study of T-cell and B-cell responses to OIT. In this review, we present evidence to illustrate what is currently known about the immunologic changes induced by OIT, explore potential mechanisms and emphasize knowledge gaps where future research is needed.

Antigen- and Epitope-Delivering Nanoparticles Targeting Liver Induce Comparable Immunotolerance in Allergic Airway Disease and Anaphylaxis as Nanoparticle-Delivering Pharmaceuticals

The targeting of natural tolerogenic liver sinusoidal endothelial cells (LSEC) by nanoparticles (NPs), decorated with a stabilin receptor ligand, is capable of generating regulatory T-cells (Tregs), which can suppress antigen-specific immune responses, including to ovalbumin (OVA), a possible food allergen. In this regard, we have previously demonstrated that OVA-encapsulating poly(lactic-co-glycolic acid) (PLGA) nanoparticles eliminate allergic airway inflammation in OVA-sensitized mice, prophylactically and therapeutically. A competing approach is a nanocarrier platform that incorporates pharmaceutical agents interfering in mTOR (rapamycin) or NF-κB (curcumin) pathways, with the ability to induce a tolerogenic state in nontargeted antigen-presenting cells system-wide. First, we compared OVA-encapsulating, LSEC-targeting tolerogenic nanoparticles (TNPs) with nontargeted NPs incorporating curcumin and rapamycin (Rapa) in a murine eosinophilic airway inflammation model, which is Treg-sensitive. This demonstrated roughly similar tolerogenic effects on allergic airway inflammation by stabilin-targeting NP^OVAversus nontargeted NPs delivering OVA plus Rapa. Reduction in eosinophilic inflammation and TH2-mediated immune responses in the lung was accompanied by increased Foxp3⁺ Treg recruitment and TGF-β production in both platforms. As OVA incorporates IgE-binding as well as non-IgE-binding epitopes, the next experiment explored the possibility of obtaining immune tolerance by non-anaphylactic T-cell epitopes. This was accomplished by incorporating OVA^323-339 and OVA^257-264 epitopes in liver-targeting NPs to assess the prophylactic and therapeutic impact on allergic inflammation in transgenic OT-II mice. Importantly, we demonstrated that the major histocompatibility complex (MHC)-II binding (former) but not the MHC-I binding (latter) epitope interfered in allergic airway inflammation, improving TNP^OVA efficacy. The epitope-specific effect was transduced by TGF-β-producing Tregs. In the final phase of experimentation, we used an OVA-induced anaphylaxis model to demonstrate that targeted delivery of OVA and its MHC-II epitope could significantly suppress the anaphylaxis symptom score, mast cell release, and the late-phase inflammatory response. In summary, these results demonstrate comparable efficacy of LSEC-targeting versus pharmaceutical PLGA nanoparticles, as well as the ability of T-cell epitopes to achieve response outcomes similar to those of the intact allergens.

Can Oral Tolerance Explain the Inconsistencies Associated with Total Dietary Diversity and Colon Cancer? A Mechanistic Systematic Review

Among the gastrointestinal tract cancers, the risk of colon cancer is strongly dependent on dietary factors. For the first time in the current review, all the original case-control studies, associated with the correlation between total dietary diversity score and colon cancer risk, were evaluated. In this regard, three databases, including PubMed/MEDLINE, Scopus, and Web of Sciences, were investigated to retrieve the related citations from 1990 until 2019. Among the included citations, three studies were finally included. In these included studies, the dietary diversity score was evaluated with 129-item and 800-item FFQs. Findings reveal that total dietary diversity can increase the risk of colon cancer in men, but not women; while, one study using 57-item FFQ reported the beneficial association of total dietary diversity with colon cancer among men. Significant demand for conducting more research to investigate the real mechanistic effects of dietary diversity on the risk of colon cancer development was demonstrated due to the inconsistent, questionable, and incomplete findings associated with the included studies.

Functional Dyspepsia and Food: Immune Overlap with Food Sensitivity Disorders

PURPOSE OF REVIEW

Functional dyspepsia (FD) is a chronic functional gastrointestinal disorder characterised by upper gastrointestinal symptoms. Here, we aimed to examine the evidence for immune responses to food in FD and overlap with food hypersensitivity conditions.

RECENT FINDINGS

A feature of FD in a subset of patients is an increase in mucosal eosinophils, mast cells, intraepithelial cytotoxic T cells and systemic gut-homing T cells in the duodenum, suggesting that immune dysfunction is characteristic of this disease. Rates of self-reported non-celiac wheat/gluten sensitivity (NCW/GS) are higher in FD patients. FD patients commonly report worsening symptoms following consumption of wheat, fermentable oligosaccharides, disaccharides, monosaccharides, or polyols (FODMAPs), high-fat foods and spicy foods containing capsaicin. Particularly, wheat proteins and fructan in wheat may drive symptoms. Immune mechanisms that drive responses to food in FD are still poorly characterised but share key effector cells to common food hypersensitivities including non-IgE-mediated food allergy and eosinophilic oesophagitis.

Climate Change and Human Health: A Review of Allergies, Autoimmunity and the Microbiome

The impact of climate change on human health is a topic of critical importance. While only recently beginning to gain attention, it is clear that immediate action is necessary to minimize this impact. In our review, we will outline a subset of these effects in detail. We will examine how climate change has worsened respiratory allergic disease. We will discuss how climate change has altered antigen exposure, possibly disrupting antigen-specific tolerance by the immune system, leading, in turn, to an increase in the prevalence of immunologic diseases. Finally, we will explore how the loss of biodiversity related to climate change may affect the microbiome, potentially leading to dysbiosis, inflammatory, autoimmune and neurologic diseases.

Precision medicine in cow's milk allergy

PURPOSE OF REVIEW

The aim of this review is to describe the role of precision medicine in the diagnosis, treatment, and monitoring of cow's milk allergy.

RECENT FINDINGS

The development of 'omics' sciences in the field of food allergy has led to a better understanding of the allergenicity of cow's milk proteins and significant advances in the knowledge of the pathogenesis and mechanisms of cow's milk allergy. Omics-based technologies allow the practitioner to better differentiate cow's milk allergy subtypes and to predict cow's milk allergy (CMA) persistence over time. Precision medicine extends the role of the oral food challenge, to determine the individual's threshold doses, and to establish tolerance to baked milk products. Other than symptom relief, dietary strategies are currently being investigated for the potential to induce tolerance. Oral immunotherapy offers a treatment option for patients with severe and persistent IgE-mediated CMA. Individual baseline-immune profiles may be predictive of cow's milk oral immunotherapy safety and efficacy.Patient data derived from current technology, in combination with the patient's history, can be translated into treatments targeted at patient-tailored interventions.

SUMMARY

The identification of novel biomarkers may improve diagnostic accuracy and also predict patient responsiveness to treatments. Integration of patient data will become increasingly important as omics technologies become more widely used in the clinical setting.

The clinical and immune outcomes after food allergen immunotherapy emphasizing the development of tolerance

PURPOSE OF REVIEW

The present review serves to outline the direction of food allergy immunotherapy research with an emphasis on clinical and immunologic outcomes. It helps to delineate sustained unresponsiveness achieved from food immunotherapy as the clinical outcome most similar to immune tolerance.

RECENT FINDINGS

We will discuss the difference between immune tolerance, desensitization, and sustained unresponsiveness in relation to food immunotherapy by discussing the clinical and immunologic changes which have been recently discovered.

SUMMARY

Research has recently shown that oral immunotherapy is most efficacious clinically at achieving desensitization to a food and sustained unresponsiveness.

Treatment for food allergy

The prevalence of IgE-mediated food allergy is an increasing public health concern effecting millions of persons worldwide. The current standard of treatment is strict avoidance of the offending food or foods, and to date, there are no regulatory approved treatments for food allergy. A significant amount of research has been directed at various forms of food immunotherapy, including oral, sublingual, and epicutaneous delivery routes. Although oral immunotherapy has shown the greatest promise for efficacy in terms of the amount of protein that can be ingested, it has also demonstrated less tolerability and a less favorable safety profile compared with sublingual immunotherapy and epicutaneous immunotherapy, which offers the least protection but has the best safety and tolerability profile. Studies have been conducted with adding adjuvants and anti-IgE to enhance either the efficacy or safety of food immunotherapy. Multiple concepts of food immunotherapy beyond these first-generation treatments are in either animal or early phase 1 studies.

Salmonella infection leads to severe intestinal inflammation and increased CD4+FoxP3+ Treg cells in streptozotocin‑induced hyperglycemic mice

Hyperglycemia promotes the growth and reproduction of bacteria, thereby increasing the probability of infection, which also causes rebound hyperglycemia. Therefore, the interactions of infection and hyperglycemia lead to the progression and deterioration of these diseases. Type 1 diabetes mellitus (T1DM) is an autoimmune disease. Studies have shown that regulatory T cells (Tregs) play a key role in maintaining islet-specific tolerance. Treg deficiency may lead to the development of early pancreatitis and T1DM, and sufficient amounts of Tregs can restore this tolerance, thereby inhibiting the occurrence of T1DM. Moreover, different subpopulations of dendritic cells (DCs) play an important role in activating autoreactive T cells and inducing autoimmune tolerance to autoantigens, which are closely related to the functional diversity caused by different phenotypes, maturation status, and the immune microenvironment of DC subpopulations. In the present study, we used streptozotocin-induced hyperglycemic mice to model T1DM and induced a Salmonella infection in the mouse model, leading to aggravated inflammation, which resulted in an elevated proportion of CD103⁺CD11b⁺ DCs and a significantly elevated proportion of CD4⁺FoxP3⁺ Tregs in the intestinal lamina propria. After co-culturing CD4⁺ T cells and DCs, we found that CD103⁺CD11b⁺ DCs could significantly promote the proliferation of CD4⁺ T cells. The elevated proportions of CD4⁺FoxP3⁺ Tregs were considered to be correlated with the increased number of CD103⁺CD11b⁺ DCs.

Evaluation of the efficiency of hydrolyzed whey formula to prevent cow's milk allergy in the BALB/c mouse model

BACKGROUND

Partially hydrolyzed milk formulas have been proposed for primary prevention in at-risk infants, but evidence of their efficiency and elucidation of the underlying mechanisms are still lacking. Thanks to a Th2-biased mouse model mimicking at-risk patients, we aimed to assess the potency of a partially hydrolyzed whey formula (pHWF) to induce oral tolerance thus preventing further cow's milk (CM) allergy.

METHODS

BALB/c mice were gavaged with pHWF, standard milk formula (SF), or vehicle only (PBS+). All mice were then orally sensitized to CM using cholera toxin and further chronically exposed to CM. Humoral (IgE, IgG1, IgG2a) and cellular (Th2/Th1/Th17 cytokine secretion; frequency of CD4+GATA3+ and CD4+CD25+Foxp3+ T cells in the spleen) responses against β-lactoglobulin (BLG) and whole caseins (CAS) were assessed, as well as a marker of elicitation of allergic reaction (mMCP-1) released after an oral challenge with CM.

RESULTS

All markers of sensitization and of allergic reaction were evidenced in the PBS+ mice and were significantly enhanced upon chronic exposure. Gavage with SF totally and durably prevented sensitization and elicitation of the allergic reaction. Conversely, pre-treatment with pHWF only reduced BLG-specific sensitization (IgE, Th2 cytokines), with no significant effect on sensitization to caseins. However, pHWF pre-treatment significantly reduced mMCP-1 concentration in plasma after CM challenges. CD4+CD25+Foxp3+ Treg cell frequency could not be correlated with tolerance efficiency.

CONCLUSION

Partially hydrolyzed whey formula only partially prevents the further development of CM allergy in this Th2-biased model. A hydrolysate from both whey and casein fractions may be more efficient.

The skin as an immune organ: Tolerance versus effector responses and applications to food allergy and hypersensitivity reactions

Skin is replete with immunocompetent cells that modulate signaling pathways to maintain a salubrious immunogenic/tolerogenic balance. This fertile immune environment plays a significant role in the development of allergic responses and sensitivities, but the mechanisms underlying these pathways have been underappreciated and underused with respect to developing therapeutics. Among the complex repertoire of cells that promote tolerogenic pathways in the periphery, 2 key classes include dendritic cells and regulatory T (Treg) cells. Immature dendritic cells are the first line of defense, patrolling the periphery, sampling antigens, and secreting cytokines that suppress immune cells and promote the survival of Treg cells. Skin-homing Treg cells also play a critical role in mitigating the reactivity of immune cells, secreting high levels of cytokines that promote tolerance. Therapeutic approaches that capitalize on our knowledge of the rich cellular and molecular environment are emerging and show great promise. We will discuss the advantages and challenges of 5 such strategies and how these therapies might mitigate the atopic march by facilitating tolerance. We conclude that skin is a multifaceted structure that provides a fertile ground for therapeutic discovery. Accordingly, ongoing work in this domain will no doubt continue to deliver exciting progress for improved health outcomes.

Microbial Adjuncts for Food Allergen Immunotherapy

PURPOSE OF REVIEW

Food allergen immunotherapy may benefit from adjunct therapies to enhance safety and efficacy. We review preclinical studies investigating the effects of probiotics and other microbial-based interventions on oral tolerance, describe the human clinical trial evidence thus far for microbial adjuncts, and discuss steps for translating research findings in this area to clinical therapy.

RECENT FINDINGS

Murine studies support that microbial-based interventions confer protection against sensitization and may augment treatment efficacy for food allergy. Microbial adjunct therapies can promote regulatory T cells and modulate Th1 vs. Th2 responses. There is a wide array of novel modalities utilizing microbial components. Ongoing efforts are focused on translating preclinical data into potential treatments. Probiotics, prebiotics, and microbial components have all been examined as microbial adjunct therapies in murine models of food allergy. The effects of probiotics appear to be strain-specific. Prebiotics and bacterial components are innovative modalities to modulate oral tolerance. Better characterization of dysbiosis in human cohorts with food allergy, deeper mechanistic understanding of microbial adjunct therapies, safety evaluation, and careful clinical trial design will be crucial for the development of microbial adjuncts for food allergen immunotherapy. Microbial adjunct therapies have the potential to enhance the efficacy, safety, and durability of food allergen immunotherapy.

Oral and Sublingual Immunotherapy for Treatment of IgE-Mediated Food Allergy

Development of active therapies for IgE-mediated food allergy is a critical action step toward alleviating the adverse medical, psychosocial, and economic burdens on affected patients and families. Significant progress has been observed specifically in the application of single-allergen oral and sublingual immunotherapy for treatment of IgE-mediated food allergy, with emphasis on milk, egg, and peanut as the primary allergens. Oral immunotherapy (OIT) has demonstrated efficacy in promoting immunomodulatory effects that lead to the clinical outcome of desensitization, defined as reduced reactivity while on active OIT, in the majority of treated individuals; however, achievement of sustained unresponsiveness following cessation of therapy has been observed in a smaller subset of treated subjects. The potential therapeutic benefits of OIT must be carefully considered in light of the significant potential for adverse events ranging from self-limited or easily treated oropharyngeal, respiratory or gastrointestinal symptoms, to persistent abdominal complaints that lead to cessation of therapy in an estimated 10-15% of treated individuals. To date, the majority of studies have focused on single-allergen OIT approaches; however, multi-allergen OIT has shown promise in initial trials and is the subject of ongoing investigation to address the complex needs of multi-food allergic individuals. Sublingual immunotherapy (SLIT) has been utilized for the treatment of food allergy and pollen-food allergy syndrome, demonstrating moderate efficacy, a favorable safety profile and variable tolerability, with oropharyngeal symptoms most commonly observed. Although studies directly comparing OIT and SLIT are limited, in general, the favorable safety profile associated with SLIT comes at the expense of reduced efficacy, while the more robust clinical effects observed with OIT come at the risk of potentially intolerable, treatment-limiting side effects. Future investigation to address specific knowledge gaps including optimal dose, duration, age of initiation, maintenance schedule, mechanisms, predictors of risk and therapeutic response will be important to maximize efficacy, minimize risk and develop personalized, effective approaches to targeting food allergy.

Perinatal antibiotic exposure alters composition of murine gut microbiota and may influence later responses to peanut antigen

Background

Accumulating evidence suggests that the gut microbiota shapes developmental processes within the immune system. Early life antibiotic use is one factor which may contribute to immune dysfunction and the recent surge in allergies by virtue of its effects on gut microbiota.

Objective and methods

As a first step towards determining whether a relationship exists between perinatal antibiotic induced changes in the gut microbiota and the later development of a peanut allergy, we exposed newborn mice to either the broad-spectrum antibiotic vancomycin or to a vehicle for 6 weeks and then used a novel murine model of peanut allergy.

Results

Early-life treatment with vancomycin resulted in a significant shift in the gut microbiota community characterized by a reduction in the abundance of firmicutes and preponderance of inflammatory proteobacteria. Mice with an antibiotic-altered microbiota, showed a localized allergic-like response characterized by ear swelling and scratching following intra-dermal peanut antigen challenge. Likewise, circulating IgE levels were increased in antibiotic-treated mice, but no evidence of a systemic allergic or anaphylactic-like response was observed. Importantly, we utilized the naturally occurring pro-inflammatory cytokine, tumor necrosis factor-α (TNF-α), rather than the more commonly used cholera toxin, as an adjuvant together with the peanut antigen.

Conclusion

Our data suggest that early antibiotic exposure promotes a shift in the gut microbiota community that may in turn, influence how mice later respond to a TNF-α + antigen challenge. However, further studies verifying the capacity of microbiota restoration to protect against allergic responses will be needed to confirm a causal role of antibiotic-induced microbiota variations in promoting allergic disease phenotypes.

Specific oral immunotherapy in food allergic patients: transient or persistent tolerance?

INTRODUCTION

The first therapeutic choice for food allergy is avoidance of the responsible food, but when this approach is not possible, specific oral desensitization could be considered as a good alternative. It is not clear yet whether the acquired tolerance is transient or persistent.

AIM

We report on a subset of 13 patients of a larger study, treated successfully with specific oral tolerance induction who experienced secondary loss of tolerance after a period of allergen avoidance.

MATERIAL AND METHODS

Thirteen patients affected by IgE-mediated food allergy: to cow milk (3 patients), to hen egg (3 patients), to cod fish (2 patients), to peanuts (1 patient) and to corn (1 patient) confirmed by a complete allergological workup and a double-blind placebo-controlled food challenge (DBPCFC), were treated with sublingual-oral desensitization. After the interruption of the maintenance phase, the laboratory tests were performed and 12 of 13 patients underwent DBPCFC.

RESULTS

Oral specific desensitization was completed successfully in all the 13 reported patients. At different times after the end of treatment, they decided, on their own initiative, to stop the ingestion of incriminated food. A new food allergen re-exposure caused adverse reactions in 12 of 13 patients. The detection of specific IgE and IgG4 during the period of allergen avoidance showed an increase in or a stable level of specific IgE and a decrease in specific IgG4 in 8 patients.

CONCLUSIONS

According to our experience, the tolerance obtained through the desensitizing treatment is transient and so the regular allergen intake is necessary for its maintenance.

IL-10 Receptor or TGF-β Neutralization Abrogates the Protective Effect of a Specific Nondigestible Oligosaccharide Mixture in Cow-Milk-Allergic Mice

Background

Dietary nondigestible, short-chain galacto-, long-chain fructo-, and pectin-derived acidic oligosaccharides (GFAs) lower the effector response in cow-milk-allergic (CMA) mice; and forkhead box P3 (Foxp3)-positive regulatory T cells (Tregs) were shown to contribute to this.

Objective

The aim of this study was to assess the contribution of interleukin 10 (IL-10) and transforming growth factor β (TGF-β) to the protective effect of the GFA diet in CMA mice.

Methods

Female C3H/HeOuJ mice, 3-4 wk old, were orally sensitized with cholera toxin (Sham) or whey and cholera toxin (Whey) 1 time/wk for 5 consecutive weeks and challenged with whey 1 wk later. The mice were fed a control or 1% GFA (9:2:1) (Whey+GFA) diet starting 2 wk before the first sensitization. In a second experiment, the mice were also injected with αIL-10 receptor (αIL-10r), αTGF-β, or isotype control antibodies 24 h before each sensitization. The acute allergic skin response, anaphylaxis score, whey-specific IgE, mucosal mast cell protease 1 (mMCP-1), and Treg frequency in the mesenteric lymph nodes (MLNs) and intestinal Foxp3, Il10, and Tgfb mRNA expression were determined.

Results

In Whey+GFA mice, intestinal Il10, Tgfb, or Foxp3 mRNA expression was 2-10 times higher (P < 0.05) and the MLN Treg frequency was 25% higher compared with Whey mice (P < 0.05). The acute allergic skin response was 50% lower in Whey+GFA mice compared with Whey mice (P < 0.01), and IL-10 receptor (IL-10r) or TGF-β neutralizing antibodies prevented this protective effect (P < 0.001). The Whey mice had higher serum mMCP-1 concentrations and whey-immunoglobulin E (-IgE) levels than Sham mice (P < 0.01), whereas these were not higher in Whey+GFA mice, and neutralizing antibodies partially interfered with these responses.

Conclusions

Dietary GFAs enhance the Treg frequency in the MLNs and mucosal IL-10 and TGF-β transcription while suppressing the allergic effector response. Neutralizing antibodies showed that the allergy-protective effect of the GFA diet was mediated by IL-10 and TGF-β in CMA mice.

Debates in Allergy Medicine: Oral immunotherapy shortens the duration of milk and egg allergy - the con argument

Oral immunotherapy (OIT) has been shown to be effective for inducing desensitization in children with cow’s milk and egg allergy. In contrast, there is limited evidence that OIT can induce tolerance or sustained unresponsiveness in food allergic patients. Sustained unresponsiveness, determined by a food challenge following a period of secondary avoidance, has been suggested to reflect a more enduring state of tolerance and is pertinent when considering the ability of OIT to shorten the duration of food allergy. While it has been shown that children who tolerate baked forms of egg and milk are more likely to develop tolerance compared to those who are allergic to baked forms of these foods, there is no convincing evidence that OIT using modified allergen in baked foods can hasten resolution of cow’s milk and egg allergy. Instead, it is likely that baked milk and baked egg tolerant children represent a sub-phenotype of milk and egg allergy that is more likely to resolve spontaneously over time.

Next generation immunotherapy for tree pollen allergies

Tree pollen induced allergies are one of the major medical and public health burdens in the industrialized world. Allergen-Specific Immunotherapy (AIT) through subcutaneous injection or sublingual delivery is the only approved therapy with curative potential to pollen induced allergies. AIT often is associated with severe side effects and requires long-term treatment. Safer, more effective and convenient allergen specific immunotherapies remain an unmet need. In this review article, we discuss the current progress in applying protein and peptide-based approaches and DNA vaccines to the clinical challenges posed by tree pollen allergies through the lens of preclinical animal models and clinical trials, with an emphasis on the birch and Japanese red cedar pollen induced allergies.

Comparison of sublingual immunotherapy and oral immunotherapy in peanut allergy

The prevalence of food allergy has been increasing over the past few decades at an alarming rate with peanut allergy affecting about 2% of children. Both oral immunotherapy (OIT) and sublingual immunotherapy (SLIT) have shown promise as a treatment option for peanut allergy. Immunotherapy induces desensitization and reduces the risk of reaction during accidental ingestion and may also enable those who are successfully desensitized to include the food allergen in their diet. OIT has been very well studied and has been found to be more efficacious that SLIT with an acceptable safety profile. However, SLIT is associated with fewer side effects. Studies indicate that a combination of SLIT and OIT may together induce a significant increase in challenge thresholds with fewer adverse events. More head-to-head clinical trials that direct compare OIT and SLIT as well as SLIT and OIT combination studies are warranted.

Food allergy to previously tolerated foods: Course and patient characteristics

BACKGROUND

The acquisition of food allergy (FA) to previously safely consumed basic food proteins is an unusual presentation of immunoglobulin E (IgE)-mediated allergic disease.

OBJECTIVE

We sought to characterize patients who developed FA to previously tolerated foods (FA-PTF), including underlying reasons for and length of elimination diet of previously tolerated foods.

METHODS

Patients (n = 30) with complaints consistent with FA to foods previously consumed safely were evaluated. Clinical history was obtained, and skin prick testing and graded oral food challenges (OFC) were performed. One fatal case of FA-PTF was reported by a physician.

RESULTS

Twenty-two of 30 patients (ages 1.2-50 years) were diagnosed with FA-PTF by OFC to milk (n = 17), egg (n = 2), and peanuts (n = 3). One additional patient with FA-PTF had a fatal reaction to milk. Anaphylactic reactions were reported in 12 of these 23 FA-PT patients (52%); 8 experienced multiple episodes. Atopic dermatitis was diagnosed in 52% (12/23) of patients, 8 of 12 as severe; overall, 18 of 23 (78%) of patients had marked personal atopic background. Sixteen patients (70%) initiated an elimination diet, 12 of whom did so on advice from a health care provider, before the appearance of allergic symptoms. However, in 4 patients with FA-PTF, reactivity to the food protein emerged during uninterrupted consumption.

CONCLUSION

Food allergy to previously tolerated foods primarily appears after an elimination diet in atopic patients. Anaphylactic reactions are common. Health care providers should consider these risks before recommending elimination diet of tolerated foods.

Possible Allergenic Role of Tropomyosin in Patients with Adverse Reactions after Fish Intake

In a recent case report, patient's anti-fish tropomyosin IgE was associated with gastrointestinal symptoms. We aimed to demonstrate on a wider scale that the panallergen tropomyosin should not be limited to invertebrate species and that clinically relevant reactions could be elicited by vertebrate tropomyosin. On the whole, 19 patients with adverse reactions after fish intake and showing negative skin tests with commercial fish extracts were included. Fish tropomyosin was recognized by 10/19 patients' IgE by immunoblotting. All patients with gastrointestinal complaints after fish intake (6/6) showed an IgE band matching with tropomyosin. Cod, albacore, and swordfish tropomyosins were recognized by most patients although 3/10 patients did not claim adverse reactions to these fish species. Immunoblotting with a battery of antigens from different fish species have a high yield of positivity at a band matching with tropomyosin molecular weight, even if they have not been claimed to be causative agents of symptoms. Tropomyosin is therefore a good candidate to be investigated as a clinically relevant fish allergen in patients who report adverse reactions after fish intake.

Critical role of plasmacytoid dendritic cells in induction of oral tolerance

BACKGROUND

Exposure to dietary constituents through the mucosal surface of the gastrointestinal tract generates oral tolerance that prevents deleterious T cell-mediated immunity. Although oral tolerance is an active process that involves emergence of CD4⁺ forkhead box p3 (Foxp3)⁺ regulatory T (Treg) cells in gut-associated lymphoid tissues (GALTs) for suppression of effector T (Teff) cells, how antigen-presenting cells initiate this process remains unclear.

OBJECTIVE

We sought to determine the role of plasmacytoid dendritic cells (pDCs), which are known as unconventional antigen-presenting cells, in establishment of oral tolerance.

METHODS

GALT-associated pDCs in wild-type mice were examined for their ability to induce differentiation of CD4⁺ Teff cells and CD4⁺Foxp3⁺ Treg cells in vitro. Wild-type and pDC-ablated mice were fed oral antigen to compare their intestinal generation of CD4⁺Foxp3⁺ Treg cells and induction of oral tolerance to protect against Teff cell-mediated allergic inflammation.

RESULTS

GALT-associated pDCs preferentially generate CD4⁺Foxp3⁺ Treg cells rather than CD4⁺ Teff cells, and such generation requires an autocrine loop of TGF-β for its robust production. A deficiency of pDCs abrogates antigen-specific de novo generation of CD4⁺Foxp3⁺ Treg cells occurring in GALT after antigenic feeding. Furthermore, the absence of pDCs impairs development of oral tolerance, which ameliorates the progression of delayed-type hypersensitivity and systemic anaphylaxis, as well as allergic asthma, accompanied by an enhanced antigen-specific CD4⁺ Teff cell response and antibody production.

CONCLUSION

pDCs are required for establishing oral tolerance to prevent undesirable allergic responses, and they might serve a key role in maintaining gastrointestinal immune homeostasis.

Precision medicine in cow's milk allergy: proteomics perspectives from allergens to patients

Cow's milk allergy (CMA) is one of the most common food allergies, especially during childhood. CMA is an immunological mediated adverse reaction to one or more cow's milk proteins, which are normally harmless to a non-allergic individual, as the result of a failure of oral tolerance. To make a correct diagnosis of CMA and a proper treatment is critical in clinical practice. Application of proteomics along with new bio-informatics tools in the field of food allergy is one of the hot topics presented in recent years. In the present review, we focus on recent applications of proteomics to the field of cow's milk allergy, from allergens quantification to the diagnosis, treatment and prognosis. Furthermore, we also shed a light on potential future directions and developments, that are parts of personalized medicine but also of the One Health approach.

SIGNIFICANCE

The field of food allergies is becoming a milestone in public health. Food allergies, in fact, can cause life-threatening reactions and profoundly influence the quality of life. Precise, fast and reliable diagnosis of food allergies, and in particular milk allergies is essential to avoid severe allergic reactions and also to prevent dangerous and eventually unnecessary dietary restrictions; but this can be difficult also due to a complex interaction of genetic background, environment, and microbiota. In this sense, proteomics represents steps toward researching food and milk allergy integrated with the clinic to improve pathophysiology, diagnosis, therapy, and prognosis.

Allergen-Specific Immunotherapies for Food Allergy

With rising prevalence of food allergy (FA), allergen-specific immunotherapy (AIT) for FA has become an active area of research in recent years. In AIT, incrementally increasing doses of inciting allergen are given with the goal to increase tolerance, initially through desensitization, which relies on regular exposure to allergen. With prolonged therapy in some subjects, AIT may induce sustained unresponsiveness, in which tolerance is retained after a period of allergen avoidance. Methods of AIT currently under study in humans include oral, sublingual, epicutaneous, and subcutaneous delivery of modified allergenic protein, as well as via DNA-based vaccines encoding allergen with lysosomal-associated membrane protein I. The balance of safety and efficacy varies by type of AIT, as well as by targeted allergen. Age, degree of sensitization, and other comorbidities may affect this balance within an individual patient. More recently, AIT with modified proteins or combined with immunomodulatory therapies has shown promise in making AIT safer and/or more effective. Though methods of AIT are neither currently advised by experts (oral immunotherapy [OIT]) nor widely available, AIT is likely to become a part of recommended management of FA in the coming years. Here, we review and compare methods of AIT currently under study in humans to prepare the practitioner for an exciting new phase in the care of food allergic patients in which improved tolerance to inciting foods will be a real possibility.

Increased Tolerance to Less Extensively Heat-Denatured (Baked) Milk Products in Milk-Allergic Children

BACKGROUND

Most milk-allergic children tolerate baked milk.

OBJECTIVE

To investigate the effect of more frequent versus less frequent introduction of higher doses of more allergenic (less heat-denatured) forms of milk (MAFM) on progression to tolerance.

METHODS

Milk-allergic children were challenged with increasing doses of MAFM; baked foods were incorporated into the diet; challenges were repeated at 6- or 12-month intervals over 36 months.

RESULTS

A total of 136 children (70% males) were enrolled in the active group (median age, 7 years). At baseline, 41 (30%) reacted to muffin, 31 (23%) to pizza, 11 (8%) to rice pudding, 43 (32%) to non-baked milk; and 10 (7%) tolerated non-baked milk. Children who tolerated baked milk but reacted to non-baked liquid milk were randomized to MAFM challenges every 6 months (n = 41) or 12 months (n = 44). At month 36, 61% children in the 6-month and 73% in the 12-month escalation groups tolerated MAFM. Overall, 41 (48%) children who ingested baked-milk diet became tolerant to non-baked milk; no difference was seen between 6- and 12- month escalations. Among children who reacted to muffin at baseline and continued avoidance, 20% developed tolerance to baked milk and 0% tolerated non-baked milk. None of the 34 children who qualified for inclusion but chose not to take part in the active study became tolerant to any form of milk by history.

CONCLUSIONS

Majority of children tolerated baked milk at baseline. Baked-milk diets were associated with progressive immunomodulation. Most children who incorporated baked milk into their diet progressed to tolerating MAFM, but there was no advantage to more frequent attempts to escalate to MAFM, per intention-to-treat analysis.

Oral Tolerance Development and Maintenance

The gastrointestinal tract has an abundant mucosal immune system to develop and maintain oral tolerance. The oral route of administration takes advantage of the unique set of immune cells and pathways involved in the induction of oral tolerance. Food allergy results from a loss of oral tolerance toward ingested antigens. Oral immunotherapy is thought to initiate desensitization through interaction of an allergen with mucosal dendritic cells that initiate downstream immune system modulation through regulatory T cells and effector T cells.

Effect of PDIA3 gene silence on colonic mast cells and visceral sensitivity of rats with irritable bowel syndrome

This study aimed to elucidate the role of PDIA3 in visceral hypersensitivity of rats with irritable bowel syndrome (IBS). Fourty eight SD rats were randomly divided into four groups (n=12): control group, IBS-empty virus group (IBS-1), IBS-PDIA3 silence group (IBS-2), and IBS-the control group (IBS-3). Visceral hypersensitivity models were established by using acetic acid enema combined with restraint stress, and assayed by abdominal withdrawal reflexes (AWR). Mast cells (MCs) in ileocecal mucosa were counted with toluidine blue staining. Degranulation of MCs was observed under electron microscopy. Serum and mucosal levels of IL-4 and IL-9 were measured with ELISA and QT-PCR. Intestinal tryptase and PAR-2 expression was examined with ELISA and Western blot. The Results showed that PDIA3 plays an important role in the formation of visceral hypersensitivity by increasing systemic and colon mucosal expressions of IL-4 and IL-9, activating mast cells and upregulating PAR-2 expression of target organs.

Peanut-specific type 1 regulatory T cells induced in vitro from allergic subjects are functionally impaired

BACKGROUND

Peanut allergy (PA) is a life-threatening condition that lacks regulator-approved treatment. Regulatory T type 1 (T_R1) cells are potent suppressors of immune responses and can be induced in vivo upon repeated antigen exposure or in vitro by using tolerogenic dendritic cells. Whether oral immunotherapy (OIT) leads to antigen-specific T_R1 cell induction has not been established.

OBJECTIVES

We sought to determine whether peanut-specific T_R1 cells can be generated in vitro from peripheral blood of patients with PA at baseline or during OIT and whether they are functional compared with peanut-specific T_R1 cells induced from healthy control (HC) subjects.

METHODS

Tolerogenic dendritic cells were differentiated in the presence of IL-10 from PBMCs of patients with PA and HC subjects pulsed with the main peanut allergens of Arachis hypogaea, Ara h 1 and 2, and used as antigen-presenting cells for autologous CD4⁺ T cells (CD4⁺ T cells coincubated with tolerogenic dendritic cells pulsed with the main peanut allergens [pea-T10 cells]). Pea-T10 cells were characterized by the presence of CD49b⁺ lymphocyte-activation gene 3 (LAG3)⁺ T_R1 cells, antigen-specific proliferative responses, and cytokine production.

RESULTS

CD49b⁺LAG3⁺ T_R1 cells were induced in pea-T10 cells at comparable percentages from HC subjects and patients with PA. Despite their antigen specificity, pea-T10 cells of patients with PA with or without OIT, as compared with those of HC subjects, were not anergic and had high T_H2 cytokine production upon peanut-specific restimulation.

CONCLUSIONS

Peanut-specific T_R1 cells can be induced from HC subjects and patients with PA, but those from patients with PA are functionally defective independent of OIT. The unfavorable T_R1/T_H2 ratio is discussed as a possible cause of PA T_R1 cell impairment.

Multifactorial Modulation of Food-Induced Anaphylaxis

Prevalence of food-induced anaphylaxis increases progressively and occurs in an unpredictable manner, seriously affecting the quality of life of patients. Intrinsic factors including age, physiological, and genetic features of the patient as well as extrinsic factors such as the intake of drugs and exposure to environmental agents modulate this disorder. It has been proven that diseases, such as mastocytosis, defects in HLA, or filaggrin genes, increase the risk of severe allergic episodes. Certain allergen families such as storage proteins, lipid transfer proteins, or parvalbumins have also been linked to anaphylaxis. Environmental factors such as inhaled allergens or sensitization through the skin can exacerbate or trigger acute anaphylaxis. Moreover, the effect of dietary habits such as the early introduction of certain foods in the diet, and the advantage of the breastfeeding remain as yet unresolved. Interaction of allergens with the intestinal cell barrier together with a set of effector cells represents the primary pathways of food-induced anaphylaxis. After an antigen cross-links the IgEs on the membrane of effector cells, a complex intracellular signaling cascade is initiated, which leads cells to release preformed mediators stored in their granules that are responsible for the acute symptoms of anaphylaxis. Afterward, they can also rapidly synthesize lipid compounds such as prostaglandins or leukotrienes. Cytokines or chemokines are also released, leading to the recruitment and activation of immune cells in the inflammatory microenvironment. Multiple factors that affect food-induced anaphylaxis are discussed in this review, paying special attention to dietary habits and environmental and genetic conditions.

Baked milk tolerant patient: Is there any special feature?

BACKGROUND

Determining whether patients with cow's milk allergy (CMA) can tolerate foods produced with baked milk could provide a better quality of life, a better prognosis, and an option for desensitization.

OBJECTIVES

The aim of this study was to identify which patients over four years of age with persistent CMA could tolerate baked milk, to compare the clinical and laboratory characteristics of reactive and non-reactive groups and to describe their clinical evolution.

MATERIALS AND METHODS

A cross-sectional study was conducted (January/13 to November/14) that included all the patients followed at a food allergy center who met the inclusion criteria. The patients underwent an oral food challenge (OFC) with a muffin (2.8g of cow's milk protein). To exclude cow's milk (CM) tolerance, the patients were subsequently challenged with unheated CM.

RESULTS

Thirty patients met all the inclusion criteria. Fourteen patients (46.7%) were considered non-reactive to baked milk and reactive to unheated CM. When the groups that were reactive and non-reactive to baked milk were compared, no statistically significant differences in clinical features were found. The prick test for α-lactalbumin (p=0.01) and casein (p=0.004) and the serum specific IgE for casein (p=0.05) presented statistical differences. After one year, none of the patients who were reactive to baked milk were ingesting CM, while 28% of the tolerant patients were consuming fresh CM (p=0.037).

CONCLUSIONS

Baked milk can be tolerated by patients with CMA, especially those with lower levels of casein and α-lactalbumin. This option can improve quality of life and accelerate tolerance.

Safety and efficacy of short-term oral immunotherapy with Cry j 1-galactomannan conjugate for Japanese cedar pollinosis: a randomized controlled trial

Current allergen-specific immunotherapy (AIT) for pollinosis requires long-term treatment with potentially severe side effects. Therefore, development of an AIT that is safe and more convenient with a shorter regimen is needed. This prospective, double-blind, placebo-controlled trial randomized 55 participants with Japanese cedar pollinosis (JCP) to active or placebo groups to test the safety and efficacy of short-term oral immunotherapy (OIT) with Cry j 1-galactomannan conjugate for JCP. Mean symptom-medication score as the primary outcome in the active group improved 27.8% relative to the placebo group during the entire pollen season. As the secondary outcomes, mean medication score in active group improved significantly, by 56.2%, compared with placebo during the entire pollen season. Mean total symptom score was similar between active and placebo groups during the entire pollen season. There were no severe treatment-emergent adverse events in the active and placebo groups. Therefore short-term OIT with Cry j 1-galactomannan conjugate is safe, and effective for reducing the amount of medication use for JCP.