Food allergy as a biological food quality control system.

Food is simultaneously a source of essential nutrients and a potential source of lethal toxins and pathogens. Consequently, multiple sensory mechanisms evolved to monitor the quality of food based on the presence and relative abundance of beneficial and harmful food substances. These include the olfactory, gustatory, and gut chemosensory systems. Here we argue that, in addition to these systems, allergic immunity plays a role in food quality control by mounting allergic defenses against food antigens associated with noxious substances. Exaggeration of these defenses can result in pathological food allergy.

Local immune response to food antigens drives meal-induced abdominal pain.

Up to 20% of people worldwide develop gastrointestinal symptoms following a meal1, leading to decreased quality of life, substantial morbidity and high medical costs. Although the interest of both the scientific and lay communities in this issue has increased markedly in recent years, with the worldwide introduction of gluten-free and other diets, the underlying mechanisms of food-induced abdominal complaints remain largely unknown. Here we show that a bacterial infection and bacterial toxins can trigger an immune response that leads to the production of dietary-antigen-specific IgE antibodies in mice, which are limited to the intestine. Following subsequent oral ingestion of the respective dietary antigen, an IgE- and mast-cell-dependent mechanism induced increased visceral pain. This aberrant pain signalling resulted from histamine receptor H1-mediated sensitization of visceral afferents. Moreover, injection of food antigens (gluten, wheat, soy and milk) into the rectosigmoid mucosa of patients with irritable bowel syndrome induced local oedema and mast cell activation. Our results identify and characterize a peripheral mechanism that underlies food-induced abdominal pain, thereby creating new possibilities for the treatment of irritable bowel syndrome and related abdominal pain disorders.

Induction of Interleukin-9-Producing Mucosal Mast Cells Promotes Susceptibility to IgE-Mediated Experimental Food Allergy.

Experimental IgE-mediated food allergy depends on intestinal anaphylaxis driven by interleukin-9 (IL-9). However, the primary cellular source of IL-9 and the mechanisms underlying the susceptibility to food-induced intestinal anaphylaxis remain unclear. Herein, we have reported the identification of multifunctional IL-9-producing mucosal mast cells (MMC9s) that can secrete prodigious amounts of IL-9 and IL-13 in response to IL-33, and mast cell protease-1 (MCPt-1) in response to antigen and IgE complex crosslinking, respectively. Repeated intragastric antigen challenge induced MMC9 development that required T cells, IL-4, and STAT6 transcription factor, but not IL-9 signals. Mice ablated of MMC9 induction failed to develop intestinal mastocytosis, which resulted in decreased food allergy symptoms that could be restored by adoptively transferred MMC9s. Finally, atopic patients that developed food allergy displayed increased intestinal expression of Il9- and MC-specific transcripts. Thus, the induction of MMC9s is a pivotal step to acquire the susceptibility to IgE-mediated food allergy.

Regulatory T cell reprogramming toward a Th2-cell-like lineage impairs oral tolerance and promotes food allergy.

Oral immunotherapy has had limited success in establishing tolerance in food allergy, reflecting failure to elicit an effective regulatory T (Treg) cell response. We show that disease-susceptible (Il4ra(F709)) mice with enhanced interleukin-4 receptor (IL-4R) signaling exhibited STAT6-dependent impaired generation and function of mucosal allergen-specific Treg cells. This failure was associated with the acquisition by Treg cells of a T helper 2 (Th2)-cell-like phenotype, also found in peripheral-blood allergen-specific Treg cells of food-allergic children. Selective augmentation of IL-4R signaling in Treg cells induced their reprogramming into Th2-like cells and disease susceptibility, whereas Treg-cell-lineage-specific deletion of Il4 and Il13 was protective. IL-4R signaling impaired the capacity of Treg cells to suppress mast cell activation and expansion, which in turn drove Th2 cell reprogramming of Treg cells. Interruption of Th2 cell reprogramming of Treg cells might thus provide candidate therapeutic strategies in food allergy.

High-Fat Diet-Induced Obesity Aggravates Food Allergy by Intestinal Barrier Destruction and Inflammation.

INTRODUCTION: The increase in high-fat diet (HFD)-induced obesity and food allergy leads to an assumption that the 2 are related. This study aims to (1) systematic verification of HFD-induced obesity aggravates food allergy and (2) explore the correlation and molecular mechanisms of HFD-induced obesity promotes food allergy. METHODS: Female BALB/c mice are divided into the control group (control), the ovalbumin (OVA)-sensitized group (OVA), the HFD-induced obesity group (HFD), and HFD-induced allergic obesity group (HFD + OVA). RESULTS: In vivo data showed that HFD feed enhance clinical symptoms and intestinal mucosa villi shed on allergic mice. Moreover, we found that HFD and OVA irritation enhanced levels of mast cell degranulation and Th2 humoral response. Additionally, Western blot analysis showed the potentiation of peroxisome proliferator-activated receptor γ (PPAR γ) remarkably reduced on intestinal in HFD and OVA group, thereby inhibiting the expression of nuclear factor kappa B (NF-κB)/PPAR γ signal the phosphorylation of NF-κB P65. CONCLUSIONS: Overall, our results suggest that HFD-induced obesity is a potential risk factor for food allergy, which related to intestinal barrier destruction and inflammation through the PPAR γ/NF-κB signaling pathway.

Tick-human interactions: from allergic klendusity to the α-Gal syndrome.

Ticks and the pathogens they transmit, including bacteria, viruses, protozoa, and helminths, constitute a growing burden for human and animal health worldwide. The ability of some animal species to acquire resistance to blood-feeding by ticks after a single or repeated infestation is known as acquired tick resistance (ATR). This resistance has been associated to tick-specific IgE response, the generation of skin-resident memory CD4+ T cells, basophil recruitment, histamine release, and epidermal hyperplasia. ATR has also been associated with protection to tick-borne tularemia through allergic klendusity, a disease-escaping ability produced by the development of hypersensitivity to an allergen. In addition to pathogen transmission, tick infestation in humans is associated with the α-Gal syndrome (AGS), a type of allergy characterized by an IgE response against the carbohydrate Galα1-3Gal (α-Gal). This glycan is present in tick salivary proteins and on the surface of tick-borne pathogens such as Borrelia burgdorferi and Anaplasma phagocytophilum, the causative agents of Lyme disease and granulocytic anaplasmosis. Most α-Gal-sensitized individuals develop IgE specific against this glycan, but only a small fraction develop the AGS. This review summarizes our current understanding of ATR and its impact on the continuum α-Gal sensitization, allergy, and the AGS. We propose that the α-Gal-specific IgE response in humans is an evolutionary adaptation associated with ATR and allergic klendusity with the trade-off of developing AGS.

IL-4-BATF signaling directly modulates IL-9 producing mucosal mast cell (MMC9) function in experimental food allergy.

BACKGROUND: This study group has previously identified IL-9-producing mucosal mast cell (MMC9) as the primary source of IL-9 to drive intestinal mastocytosis and experimental IgE-mediated food allergy. However, the molecular mechanisms that regulate the expansion of MMC9s remain unknown. OBJECTIVES: This study hypothesized that IL-4 regulates MMC9 development and MMC9-dependent experimental IgE-mediated food allergy. METHODS: An epicutaneous sensitization model was used and bone marrow reconstitution experiments were performed to test the requirement of IL-4 receptor α (IL-4Rα) signaling on MMC9s in experimental IgE-mediated food allergy. Flow cytometric, bulk, and single-cell RNA-sequencing analyses on small intestine (SI) MMC9s were performed to illuminate MMC9 transcriptional signature and the effect of IL-4Rα signaling on MMC9 function. A bone marrow-derived MMC9 culture system was used to define IL-4-BATF signaling in MMC9 development. RESULTS: Epicutaneous sensitization- and bone marrow reconstitution-based models of IgE-mediated food allergy revealed an IL-4 signaling-dependent cell-intrinsic effect on SI MMC9 accumulation and food allergy severity. RNA-sequencing analysis of SI-MMC9s identified 410 gene transcripts reciprocally regulated by IL-4 signaling, including Il9 and Batf. Insilico analyses identified a 3491-gene MMC9 transcriptional signature and identified 2 transcriptionally distinct SI MMC9 populations enriched for metabolic or inflammatory programs. Employing an in vitro MMC9-culture model system showed that generation of MMC9-like cells was induced by IL-4 and this was in part dependent on BATF. CONCLUSIONS: IL-4Rα signaling directly modulates MMC9 function and exacerbation of experimental IgE-mediated food allergic reactions. IL-4Rα regulation of MMC9s is in part BATF-dependent and occurs via modulation of metabolic transcriptional programs.

Aggravation of Food Allergy by Skin Sensitization via Systemic Th2 Enhancement.

BACKGROUND: Recently, the relationship between antigen contact via skin (skin sensitization) and the development of food allergies has gained increasing attention. However, few studies have examined the effects of skin sensitization on healthy skin. OBJECTIVE: To examine the effect of sensitization in healthy skin on IgE and cytokine production during food allergy development. METHODS: The effect of skin sensitization on food allergy was evaluated using DO11.10 mice whose T cells express ovalbumin (OVA)-specific T-cell receptors. OVA was applied to the back skin of mice dehaired by various methods, and then food allergy was induced by providing them with an OVA-containing diet. OVA-specific IgE production in the sera and decreases in body temperature due to anaphylactic reaction were measured as indicators of food allergy. In addition, IL-4 production and proliferation of splenocytes were measured in mice with food allergy after skin sensitization. RESULTS: Skin sensitization in healthy skin increased IgE production and exacerbated anaphylactic symptoms induced by ingesting the antigen. Moreover, skin sensitization enhanced IL-4 production from splenocytes during the onset of food allergy. In contrast, oral tolerance was induced even after establishing skin sensitization. CONCLUSION: Skin sensitization temporarily exacerbated food allergy by enhancing systemic Th2 responses. These findings will help identify the mechanisms involved in food allergy and help develop treatments.

Differences in oral food challenge reaction severity based on increasing age in a pediatric population.

BACKGROUND: Food allergy reactions range from mild to severe with differences in age appearing to be an important factor associated with reaction severity. OBJECTIVE: To define differences in oral food challenge (OFC) reaction severity in pediatric patients from infancy to adolescence using objective clinical outcomes and standardized reaction grading tools. METHODS: Retrospective review of all positive OFC results at 2 large institutions between September 2016 and February 2019. Reaction severity was defined by presence of cardiovascular, neurologic, lower respiratory, or laryngeal symptoms, epinephrine requirement, and grading using 2 established food allergy reaction scales. RESULTS: Infants and toddlers had fewer reactions involving cardiovascular, neurologic, lower respiratory, or laryngeal symptoms compared with older age groups. Epinephrine was also required less frequently during reactions in infants and toddlers, compared with older age groups. There was no difference in reaction severity in infants and toddlers based on clinical history of eczema. Increasing age was significantly correlated with increased epinephrine requirement (R2 = 0.12, P = .002), elevated Consortium of Food Allergy Research score (R2 = .012, P = .003), and approached significance for increased Practical Allergy score (R2 = .005, P = .05). History of asthma and sesame allergy were identified to be positively correlated with more severe reactions. CONCLUSION: Infants and young toddlers have less severe reactions during OFCs compared with older age groups supporting early food introduction practices. In children under 12 months of age, severe reactions are most rare calling into question screening practices using specific allergy testing before food introduction. Standardized reaction grading tools may be valuable instruments to categorize reaction severity during OFCs.

Management of acute food protein-induced enterocolitis syndrome emergencies at home and in a medical facility.

OBJECTIVE: Acute food protein-induced enterocolitis syndrome (FPIES) is characterized by delayed repetitive vomiting after ingestion of a trigger food, and severe reactions may lead to dehydration, hypotension, and shock. We provide recommendations on management of FPIES emergencies in a medical facility and at home. DATA SOURCES: This review summarizes the literature on clinical context, pathophysiology, presentation, and treatment of FPIES emergencies. STUDY SELECTIONS: We referred to the 2017 International Consensus Guidelines for the Diagnosis and Management of FPIES and performed a literature search identifying relevant recent primary articles and review articles on clinical management. RESULTS: Management of FPIES emergencies in a medical facility is based on severity of symptoms and involves rehydration, ondansetron, and corticosteroids. A proactive approach for reactions occurring at home involves prescribing oral ondansetron and providing an individualized treatment plan based on the evolution of symptoms and severity of past reactions. A better understanding of the pathophysiology of FPIES and randomized trials on ondansedron and cocorticosteroid use could lead to more targeted treatments. CONCLUSION: Children with FPIES are at risk for severe symptoms constituting a medical emergency. Management of FPIES emergencies is largely supportive, with treatment tailored to the symptoms, severity of the patient's condition, location of reaction, and reaction history.

The evolution of food protein-induced enterocolitis syndrome: From a diagnosis that did not exist to a condition in need of answers.

OBJECTIVE: Although food protein-induced enterocolitis syndrome (FPIES) was first described approximately 50 years ago and research is increasing, there are still considerable unmet needs in FPIES. This article catalogs the areas of progress and areas for further research. DATA SOURCES: Through our personal experiences in caring for patients with FPIES, our personal research, and a review of the existing FPIES literature as indexed in PubMed, we explored what is known and what is needed in FPIES. STUDY SELECTIONS: The studies that have improved the knowledge of FPIES, defined phenotypes, allowed for better-informed management of FPIES, and laid the groundwork for further research. RESULTS: Further research is needed in the areas of prevalence, natural history, trigger foods, threshold doses, how and when to perform oral food challenges, and immunopathogenesis of this disorder. Development of a biomarker and determination of the best method to treat reactions is also needed. Furthermore, FPIES has a substantial psychosocial and economic impact on families, and more research is needed in developing and implementing ameliorating strategies. CONCLUSION: By partnering together, health care providers, advocacy organizations, and families can continue to advance our understanding and improve the care of patients and families living with FPIES.

Food protein-induced enterocolitis syndrome: Dynamic relationship among gastrointestinal symptoms, immune response, and the autonomic nervous system.

OBJECTIVE: To explore the relationship among gastrointestinal (GI) symptoms, immune response, and autonomic nervous system (ANS) in food protein-induced enterocolitis syndrome (FPIES) in relation to the current understanding of disease phenotype and pathogenesis. DATA SOURCES: Relevant studies related to FPIES, GI symptomatology, and ANS were reviewed. Literature search was performed using PubMed, with keyword combinations including but not limited to FPIES, allergic GI disorders, ANS, autonomic dysfunction, dysautonomia, GI, diarrhea, vomiting, neuroimmune, and clinical phenotyping tools. STUDY SELECTIONS: Peer-reviewed case-control studies, observational studies, reviews and guidelines, and systematic reviews related to FPIES and ANS were selected for review. RESULTS: There is limited research directly relating GI symptoms and FPIES to the ANS and immunologic response. To support the proposed mechanisms of action related to patient symptoms, studies relevant to coexisting GI-autonomic processes and FPIES immunologic triggers were examined. These related disease processes were extrapolated to FPIES based on the current knowledge of FPIES phenotype and pathogenesis. CONCLUSION: The etiology of FPIES and the underlying mechanisms triggering symptoms are not well understood. On the basis of the exaggerated GI symptoms and hemodynamic response observed, the ANS likely plays an important role in FPIES, possibly as a compensatory response. The trigger for this cascade of symptoms may be related to the disruption of immunologic homeostasis that typically contributes to immune tolerance. To more accurately evaluate FPIES pathophysiology necessitates understanding the diverse spectrum of presenting symptoms. A consistent and comprehensive symptom assessment tool may improve our understanding of this dynamic relationship.

Gastrointestinal immunopathology of food protein-induced enterocolitis syndrome and other non-immunoglobulin E-mediated food allergic diseases.

OBJECTIVE: To provide a concise summary of the current literature regarding gastrointestinal immunopathology of food protein-induced enterocolitis syndrome (FPIES) and other non-immunoglobulin E (IgE)-mediated food allergic diseases. DATA SOURCES: Data were extracted from PubMed, MEDLINE, and ScienceDirect databases. STUDY SELECTIONS: Original articles, review articles, and guidelines published in the past 5 years in peer-reviewed journals were first summarized. The original articles cited were then reviewed and relevant results were extracted. RESULTS: Patients with FPIES and non-IgE-mediated food allergic diseases developed vomiting, diarrhea, and food aversion expelled food allergen from their bodies. Aside from T helper type 2 (TH2) immunity, TH1, TH17, innate immunity, and epithelial mucosal barrier defect were also found to be important in the pathogenesis. Eosinophils, widely identified in the biopsy samples, were key players or were late-recruited cells for tissue repairs in those diseases. Intestinal dysbiosis and their metabolites stimulated enterochromaffin cells or enteroendocrine cells to produce serotonin, interfering with intestinal motility and subsequently affecting brain function. FPIES and non-IgE-mediated food allergic diseases were likely part of the atopic march. Allergic inflammation in intestinal mucosa might result in subsequent inflammation in the airway mucosa, suggesting the theory of "one mucosa, one disease." CONCLUSION: The immune responses of FPIES and non-IgE-mediated food allergic diseases were not limited to the gastrointestinal tract, but also trigger wider inflammatory responses beyond it. Further research will be required to determine the systemic effect and intestinal microbiome of those diseases.

Food protein-induced enterocolitis syndrome epidemiology.

OBJECTIVE: Food protein-induced enterocolitis syndrome (FPIES) is a condition with heterogeneous features (ie, age at presentation, severity, food triggers, comorbidities) and is not as rare as initially believed. In the last few years, the first population-based epidemiologic study, few prospective birth cohort evaluating FPIES prevalence, and several larger (>100 patients) studies have been published, making epidemiologic estimation more reliable. In this review, we report on the available data on the epidemiology of FPIES. DATA SOURCES: PubMed review using the following words: FPIES, epidemiology, and prevalence. STUDY SELECTIONS: The review focused on the population-based epidemiologic study, few prospective birth cohort evaluating FPIES prevalence, and several larger (>100 patients) studies. RESULTS: We identified 8 population or cohort studies. CONCLUSION: FPIES is not rare in both children and adults and may affect as many as 900,000 people in the United States alone. Most children and adult with FPIES seem to react to 1 to 2 foods; however, they may need further diet restriction owing to high level of comorbidity with immunoglobulin E-mediated food allergies and eosinophilic esophagitis. Globally, cow's milk, rice/oat, and seafood seem to be the most common triggers.

A scoping review of the caregiver burden of pediatric food allergy.

OBJECTIVE: Although a number of articles have described the psychosocial impact of raising a child with a food allergy, recent attempts at synthesizing this literature have been narrow in focus or methodologically limited. Consequently, this study aimed to synthesize both the quantitative and qualitative literature to achieve a better understanding of the psychosocial and financial burdens faced by families who raise children with food allergy. DATA SOURCES: Searches were performed on PubMed, Scopus, PsycInfo, and Cumulative Index to Nursing and Allied Health Literature databases for articles related to the psychosocial and financial burden experienced by individuals who care for a child with food allergy. STUDY SELECTIONS: English language, original research articles were included in this review. RESULTS: A total of 54 articles were deemed eligible for review. Results from the quantitative literature revealed that parents of children with food allergy (ie, food allergy and food protein-induced enterocolitis, proctocolitis, and enteropathy) consistently reported lower quality of life than their comparison groups. Within-group analyses suggest that this burden is increased for parents who manage multiple food allergies, severe food allergy, and comorbid allergic conditions. Thematic synthesis of the qualitative literature suggests that the psychosocial burden shouldered by parents of children with food allergy stems, in part, from the unpredictable threat of exposure and the practical and social burdens of managing a food allergy. In addition to psychosocial burdens, a small but growing body of literature suggests that families with food allergy also incur greater financial costs. CONCLUSION: Findings suggest that pediatric food allergy imposes considerable burdens on parents both quantitatively and qualitatively.

Food protein-induced enterocolitis syndrome oral food challenge: Time for a change?

OBJECTIVE: Food protein-induced enterocolitis syndrome (FPIES) is typically diagnosed based on a characteristic clinical history; however, an oral food challenge (OFC) may be necessary to confirm the diagnosis or evaluate for the development of tolerance. FPIES OFC methods vary globally, and there is no universally agreed upon protocol. The objective of this review is to summarize reported FPIES OFC approaches and consider unmet needs in diagnosing and managing FPIES. DATA SOURCES: PubMed database was searched using the keywords food protein-induced enterocolitis syndrome, oral food challenge, cow milk allergy, food allergy, non-immunoglobulin E-mediated food allergy and FPIES. STUDY SELECTIONS: Primary and review articles were selected based on relevance to the diagnosis of FPIES and the FPIES OFC. RESULTS: We reviewed the history of FPIES and the evolution and variations in the FPIES OFC. A summary of current literature suggests that most patients with FPIES will react with 25% to 33% of a standard serving of the challenged food, there is little benefit to offering a divided dose challenge unless there is suspicion of specific immunoglobulin E to the food being challenged, reactions typically appear within 1 to 4 hours of ingestion, and reactions during OFC rarely result in emergency department or intensive care unit admission. CONCLUSION: International standardization in the FPIES OFC approach is necessary with particular attention to specific dose administration across challenged foods, timing between the patient's reaction and offered OFC to verify tolerance, patient safety considerations before the OFC, and identification of characteristics that would indicate home reintroduction is appropriate.

A severity grading system of food-induced acute allergic reactions to avoid the delay of epinephrine administration.

BACKGROUND: Substantial discrepancies among anaphylaxis severity scores may delay epinephrine administration. OBJECTIVE: The study aims to develop a transparent severity grading system of food-induced acute allergic reactions with a decision model for epinephrine use. METHODS: The natural course of 315 acute food-induced allergic reactions in children hospitalized at the Allergology department between May 2016 and July 2019 owing to follow-up treatment and allergy diagnostics was evaluated. The severity of episodes was classified according to the 5 most accepted grading systems. The interrater reliability of classification between anaphylaxis severity scores was assessed. All symptoms were grouped into a heat map according to their real-life incidence and clinical relevance. Based on the heat map analysis, a severity grading system of food-induced acute allergic reactions in children with the epinephrine administration decision model was created. RESULTS: Data from 259 food-induced anaphylaxis episodes in 157 children were included in the analysis. Comparing the grading systems, we observed a 24.7% to 70.2% disagreement between severity scores. The heat map illustrated a strong association between 29 symptoms and their categorization. A new severity grading system was developed and a 2-stage decision model was proposed: "epinephrine yes" (any rapidly progressing symptoms, even mild ones or from 1 organ system; any symptoms from more than 1 organ system; or every grade of anaphylaxis), and "epinephrine available and prepared to use" (nonprogressing mild systemic allergic reaction from 1 system area only; no anaphylaxis). CONCLUSION: A new severity grading system of food-induced acute allergic reactions in children could serve as a clinical tool for health care professionals to avoid epinephrine administration delay.

Omeprazole inhibits IgE-mediated mast cell activation and allergic inflammation induced by ingested allergen in mice.

BACKGROUND: Patients with eosinophilic esophagitis have increased numbers of mucosal mast cells. Administration of the proton pump inhibitor omeprazole can reduce both esophageal mast cell and eosinophil numbers and attenuate type 2 inflammation in these subjects. OBJECTIVE: Given that maintenance of an acidic environment within granules is important for mast cell homeostasis, we sought to evaluate the effects of omeprazole on mast cell functions including development, IgE:FcεRI-mediated activation, and responses to food allergen. METHODS: Mast cell degranulation, cytokine secretion, and early signaling events in the FcεRI pathway, including protein kinase phosphorylation and Ca2+ flux, were measured after IgE crosslinking in murine bone marrow-derived mast cells and human cord blood-derived mast cells. The effects of omeprazole on these responses were investigated as was its impact on mast cell-dependent anaphylaxis and food allergy phenotypes in vivo. RESULTS: Murine and human mast cells treated with omeprazole exhibited diminished degranulation and release of cytokines and histamine in response to allergen. In murine mast cells, phosphorylation of protein kinases, ERK and SYK, was decreased. Differentiation of mast cells from bone marrow progenitors was also inhibited. IgE-mediated passive anaphylaxis was blunted in mice treated with omeprazole as was allergen-induced mast cell expansion and mast cell activation in the intestine in a model of food allergy. CONCLUSIONS: Our findings suggest that omeprazole targets pathways important for the differentiation and activation of murine mast cells and for the manifestations of food allergy and anaphylaxis.

Clinical signs and diagnosis of feline atopic syndrome: detailed guidelines for a correct diagnosis.

BACKGROUND: Feline atopic syndrome (FAS) describes a spectrum of hypersensitivity disorders characterised by highly diverse clinical presentations including skin, gastrointestinal and respiratory systems. Among these disorders is feline atopic skin syndrome (FASS), in which hypersensitivity is typically associated with environmental allergens, although food allergy may coexist. Involvement of other organ systems (e.g. asthma) also may occur. Because of its highly heterogeneous clinical presentation, diagnosis of FASS can be challenging. OBJECTIVES: A subgroup of the International Committee on Allergic Diseases of Animals was tasked to summarise the most current information on the clinical presentations of FASS and to develop diagnostic guidelines. METHODS AND MATERIALS: Online citation databases and abstracts from international meetings were searched for publications related to feline allergic conditions. These were combined with expert opinion where necessary. RESULTS: A total of 107 publications relevant to this review were identified. Compilation of these data enabled development of a detailed description of the clinical features of FASS and development of guidelines focusing on systematic elimination of other skin conditions with similar clinical characteristics. As allergen tests are frequently used by dermatologists to support a clinical diagnosis of FASS, a brief review of these methodologies was also performed. CONCLUSIONS AND CLINICAL IMPORTANCE: In a similar way to atopic dermatitis in dogs, FASS is a clinical diagnosis based on the presence of compatible clinical signs and exclusion of other diseases with similar clinical features. Elimination or exclusion of fleas/flea allergy, other parasites, infections and food allergy is mandatory before reaching a diagnosis of FASS.

Many Patients With Irritable Bowel Syndrome Have Atypical Food Allergies Not Associated With Immunoglobulin E.

BACKGROUND & AIMS: Confocal laser endomicroscopy (CLE) is a technique that permits real-time detection and quantification of changes in intestinal tissues and cells, including increases in intraepithelial lymphocytes and fluid extravasation through epithelial leaks. Using CLE analysis of patients with irritable bowel syndrome (IBS), we found that more than half have responses to specific food components. Exclusion of the defined food led to long-term symptom relief. We used the results of CLE to detect reactions to food in a larger patient population and analyzed duodenal biopsy samples and fluid from patients to investigate mechanisms of these reactions. METHODS: In a prospective study, 155 patients with IBS received 4 challenges with each of 4 common food components via the endoscope, followed by CLE, at a tertiary medical center. Classical food allergies were excluded by negative results from immunoglobulin E serology analysis and skin tests for common food antigens. Duodenal biopsy samples and fluid were collected 2 weeks before and immediately after CLE and were analyzed by histology, immunohistochemistry, reverse transcription polymerase chain reaction, and immunoblots. Results from patients who had a response to food during CLE (CLE+) were compared with results from patients who did not have a reaction during CLE (CLE-) or healthy individuals (controls). RESULTS: Of the 108 patients who completed the study, 76 were CLE+ (70%), and 46 of these (61%) reacted to wheat. CLE+ patients had a 4-fold increase in prevalence of atopic disorders compared with controls (P = .001). Numbers of intraepithelial lymphocytes were significantly higher in duodenal biopsy samples from CLE+ vs CLE- patients or controls (P = .001). Expression of claudin-2 increased from crypt to villus tip (P < .001) and was up-regulated in CLE+ patients compared with CLE- patients or controls (P = .023). Levels of occludin were lower in duodenal biopsy samples from CLE+ patients vs controls (P = .022) and were lowest in villus tips (P < .001). Levels of messenger RNAs encoding inflammatory cytokines were unchanged in duodenal tissues after CLE challenge, but eosinophil degranulation increased, and levels of eosinophilic cationic protein were higher in duodenal fluid from CLE+ patients than controls (P = .03). CONCLUSIONS: In a CLE analysis of patients with IBS, we found that more than 50% of patients could have nonclassical food allergy, with immediate disruption of the intestinal barrier upon exposure to food antigens. Duodenal tissues from patients with responses to food components during CLE had immediate increases in expression of claudin-2 and decreases in occludin. CLE+ patients also had increased eosinophil degranulation, indicating an atypical food allergy characterized by eosinophil activation.