Thermostable allergens in canned fish: Evaluating risks for fish allergy.

BACKGROUND: Major fish allergens, including parvalbumin (PV), are heat stable and can withstand extensive cooking processes. Thus, the management of fish allergy generally relies on complete avoidance. Fish-allergic patients may be advised to consume canned fish, as some fish-allergic individuals have reported tolerance to canned fish. However, the safety of consuming canned fish has not been evaluated with comprehensive immunological and molecular analysis of canned fish products. METHODS: We characterized the in vitro immunoreactivity of serum obtained from fish-allergic subjects to canned fish. Seventeen canned fish products (salmon n = 8; tuna n = 7; sardine n = 2) were assessed for the content and integrity of PV using allergen-specific antibodies. Subsequently, the sIgE binding of five selected products was evaluated for individual fish-allergic patients (n = 53). Finally, sIgE-binding proteins were identified by mass spectrometry. RESULTS: The canned fish showed a markedly reduced PV content and binding to PV-specific antibodies compared with conventionally cooked fish. However, PV and other heat-stable fish allergens, including tropomyosin and collagen, still maintained their sIgE-binding capacity. Of 53 patients, 66% showed sIgE binding to canned fish proteins. The canned sardine contained proteins bound to sIgE from 51% of patients, followed by canned salmon (43%-45%) and tuna (8%-17%). PV was the major allergen in canned salmon and sardine. Tropomyosin and/or collagen also showed sIgE binding. CONCLUSION: We showed that canned fish products may not be safe for all fish-allergic patients. Canned fish products should only be considered into the diet of individuals with fish allergy, after detailed evaluation which may include in vitro diagnostics to various heat-stable fish allergens and food challenge conducted in suitable environments.

The first reptilian allergen and major allergen for fish-allergic patients: Crocodile ß-parvalbumin.

BACKGROUND: Clinical cross-reactivity between bony fish, cartilaginous fish, frog, and chicken muscle has previously been demonstrated in fish-allergic patients. In indicative studies, two reports of anaphylaxis following the consumption of crocodile meat and IgE-cross-binding were linked to the major fish allergen parvalbumin (PV). This study investigates IgE-binding proteins in crocodile meat with a focus on PV and their clinical relevance. METHODS: Proteins were extracted from muscle tissue of crocodile, three bony fish, and two cartilaginous fish. A cohort of fish-allergic pediatric patients (n = 77) underwent allergen skin prick testing (SPT) to three fish preparations (n = 77) and crocodile (n = 12). IgE-binding proteins were identified and quantified by SDS-PAGE, mass spectrometric analyses, and immunoblotting using commercial and in-house antibodies, as well as individual and pooled patients' serum. PV isoforms were purified or recombinantly expressed before immunological analyses, including human mast cell degranulation assay. RESULTS: Of the tissues analyzed, PV was most abundant in heated crocodile preparation, triggering an SPT of ≥3 mm in 8 of 12 (67%) fish-allergic patients. Seventy percent (31 of 44) of fish PV-sensitized patients demonstrated IgE-binding to crocodile PV. Crocodile ß-PV was the major IgE-binding protein but 20-fold less abundant than α-PV. Cellular reactivity was demonstrated for ß-PV and epitopes predicted, explaining frequent IgE-cross-binding of ß-PVs. Both PV isoforms are now registered as the first reptile allergens with the WHO/IUIS (ß-PV as Cro p 1 and α-PV as Cro p 2). CONCLUSION: Fish-allergic individuals may be at risk of an allergy to crocodile and should seek specialist advice before consuming crocodilian meat.

Expanding the allergen repertoire of salmon and catfish.

BACKGROUND: Diagnostic tests for fish allergy are hampered by the large number of under-investigated fish species. Four salmon allergens are well-characterized and registered with the WHO/IUIS while no catfish allergens have been described so far. In 2008, freshwater-cultured catfish production surpassed that of salmon, the globally most-cultured marine species. We aimed to identify, quantify, and compare all IgE-binding proteins in salmon and catfish. METHODS: Seventy-seven pediatric patients with clinically confirmed fish allergy underwent skin prick tests to salmon and catfish. The allergen repertoire of raw and heated protein extracts was evaluated by immunoblotting using five allergen-specific antibodies and patients' serum followed by mass spectrometric analyses. RESULTS: Raw and heated extracts from catfish displayed a higher frequency of IgE-binding compared to those from salmon (77% vs 70% and 64% vs 53%, respectively). The major fish allergen parvalbumin demonstrated the highest IgE-binding capacity (10%-49%), followed by triosephosphate isomerase (TPI; 19%-34%) in raw and tropomyosin (6%-32%) in heated extracts. Six previously unidentified fish allergens, including TPI, were registered with the WHO/IUIS. Creatine kinase from salmon and catfish was detected by IgE from 14% and 10% of patients, respectively. Catfish L-lactate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, pyruvate kinase, and glucose-6-phosphate isomerase showed IgE-binding for 6%-13% of patients. In salmon, these proteins could not be separated successfully. CONCLUSIONS: We detail the allergen repertoire of two highly farmed fish species. IgE-binding to fish tropomyosins and TPIs was demonstrated for the first time in a large patient cohort. Tropomyosins, in addition to parvalbumins, should be considered for urgently needed improved fish allergy diagnostics.

An exploration of factors associated with food protein-induced enterocolitis syndrome: Birth, infant feeding and food triggers.

BACKGROUND: Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergic disorder with a well-characterized phenotype, but limited understanding of factors associated with food cross-reactivity, severity and tolerance. METHODS: A retrospective cohort study spanning 20 years on children with acute FPIES from a single paediatric tertiary centre in New South Wales, Australia, focusing on identifying food trigger co-associations and factors associated with reaction severity, multiple trigger FPIES and/or tolerance was performed. RESULTS: A total of 168 individuals with 329 recorded FPIES episodes between 1997 and 2017 were included. 49% were male. The median age at first reaction was 5 months, and median age at diagnosis was 9 months. 73% experienced at least one severe FPIES reaction. Rice (45%), cow's milk (30%) and soya (13%) were the most common triggers. Rice or cow's milk FPIES was strongly associated with increased odds of having multiple trigger FPIES. The odds of having multiple food FPIES and severe reactions were slightly decreased with vaginal delivery. No factors were associated with increased risk of severe reactions. Infants with rice and grains FPIES outgrew their reactions at an earlier age, compared to those with fish FPIES. CONCLUSIONS: Rice remains the most common trigger in Australia with co-associations between rice/oats and cow's milk/soya observed. This suggests that taxonomically related foods may share similar protein structure and trigger similar mechanisms of antigen recognition. Vaginal delivery may have a mild protective effect on the development of multiple FPIES and severe reactions. No other features from birth or infant-feeding history influenced outcomes in FPIES.

Variability of allergens in commercial fish extracts for skin prick testing.

BACKGROUND: Commercial allergen extracts for allergy skin prick testing (SPT) are widely used for diagnosing fish allergy. However, there is currently no regulatory requirement for standardization of protein and allergen content, potentially impacting the diagnostic reliability of SPTs. We therefore sought to analyse commercial fish extracts for the presence and concentration of fish proteins and in vitro IgE reactivity using serum from fish-allergic patients. METHODS: Twenty-six commercial fish extracts from five different manufacturers were examined. The protein concentrations were determined, protein compositions analysed by mass spectrometry, followed by SDS-PAGE and subsequent immunoblotting with antibodies detecting 4 fish allergens (parvalbumin, tropomyosin, aldolase and collagen). IgE-reactive proteins were identified using serum from 16 children with confirmed IgE-mediated fish allergy, with focus on cod, tuna and salmon extracts. RESULTS: The total protein, allergen concentration and IgE reactivity of the commercial extracts varied over 10-fold between different manufacturers and fish species. The major fish allergen parvalbumin was not detected by immunoblotting in 6/26 extracts. In 7/12 extracts, five known fish allergens were detected by mass spectrometry. For cod and tuna, almost 70% of patients demonstrated the strongest IgE reactivity to collagen, tropomyosin, aldolase A or ß-enolase but not parvalbumin. CONCLUSIONS: Commercial fish extracts often contain insufficient amounts of important allergens including parvalbumin and collagen, resulting in low IgE reactivity. A comprehensive proteomic approach for the evaluation of SPT extracts for their utility in allergy diagnostics is presented. There is an urgent need for standardized allergen extracts, which will improve the diagnosis and management of fish allergy.

Food protein-induced enterocolitis syndrome: guidelines summary and practice recommendations.

Food protein-induced enterocolitis syndrome (FPIES) is a poorly understood non-IgE gastrointestinal-mediated food allergy that predominantly affects infants and young children. Cells of the innate immune system appear to be activated during an FPIES reaction. Acute FPIES typically presents between one and 4 hours after ingestion of the trigger food, with the principal symptom being profuse vomiting, and is often accompanied by pallor and lethargy. Additional features can include hypotension, hypothermia, diarrhoea, neutrophilia and thrombocytosis. In Australia, the most commonly reported foods responsible for FPIES are (in descending order) rice, cow's milk, egg, oats and chicken. Most children with FPIES react to only one food trigger, and thus, avoidance of multiple foods is often not indicated. FPIES is often misdiagnosed as sepsis or gastroenteritis. However, a diagnosis of FPIES is favoured if there is rapid resolution of symptoms within hours of presentation, an absence of fever, and a lack of a significant rise in C-reactive protein at presentation. Diagnosis is often hampered by the lack of awareness of FPIES, absence of reliable biomarkers, the non-specific nature of the presenting symptoms, and the delay between allergen exposure and symptoms. Although some national peak allergy bodies have attempted to improve the diagnosis and management of FPIES, up until 2017 there were no internationally agreed guidelines for its diagnosis and management.

Food protein-induced enterocolitis syndrome in Australia: A population-based study, 2012-2014.

BACKGROUND: Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated gastrointestinal allergic disorder. Large population-based FPIES studies are lacking. OBJECTIVE: We sought to determine the incidence and clinical characteristics of FPIES in Australian infants. METHODS: An Australia-wide survey (2012-2014) was undertaken through the Australian Paediatric Surveillance Unit, with monthly notification of new cases of acute FPIES in infants aged less than 24 months by 1400 participating pediatricians. RESULTS: Two hundred thirty infants with FPIES were identified. The incidence of FPIES in Australian infants (<24 months) was 15.4/100,000/y. Median age of first episode, diagnosis, and notification were 5, 7, and 10 months, respectively. There was no sex predilection. Seven percent of infants had siblings with a history of FPIES, and 5% reacted during exclusive breast-feeding. Sixty-eight had a single food trigger (20% had 2 and 12% had ≥3 food triggers). The most common FPIES triggers were rice (45%), cow's milk (33%), and egg (12%). Fifty-one percent of infants reacted on their first known exposure. Infants with FPIES to multiple versus single food groups were younger at the initial episode (4.6 vs 5.8 months [mean], P = .001) and more frequently had FPIES to fruits, vegetables, or both (66% vs 21%, P < .0001). Infants exclusively breast-fed for more than 4 months had a trend toward lower rates of FPIES to multiple food groups (23% vs 36%, P = .06). Sixty-four percent of infants with FPIES to multiple foods, which included cow's milk, had coassociated FPIES to solid foods. Forty-two percent of infants with FPIES to fish reacted to other food groups. CONCLUSIONS: FPIES is not rare, with an estimated incidence of 15.4/100,000/y. Rice is the most common food trigger in Australia. Factors associated with FPIES to multiple foods included early-onset disease and FPIES to fruits, vegetables, or both.

Immunodeficiency in CHARGE syndrome.

Immunodeficiency can occur in CHARGE syndrome, with immunophenotypes including reduction in T-cell counts, combined T-B cell defects rarely requiring antibiotic prophylaxis or immunoglobulin replacement, and severe combined immunodeficiency, which is fatal without immune reconstitution. However, the prevalence of immunodeficiency in CHARGE syndrome remains unclear with few prospective studies. In this review, we examine the existing literature covering immunodeficiency associated with CHARGE syndrome, compare these with immunodeficiencies reported in 22q11.2 deletion syndrome (a condition that shares many phenotypic characteristics with CHARGE syndrome) and suggest future research priorities.

Mevalonate kinase deficiency leads to decreased prenylation of Rab GTPases.

Mevalonate kinase deficiency (MKD) is caused by mutations in a key enzyme of the mevalonate-cholesterol biosynthesis pathway, leading to recurrent autoinflammatory disease characterised by enhanced release of interleukin-1ß (IL-1ß). It is currently believed that the inflammatory phenotype of MKD is triggered by temperature-sensitive loss of mevalonate kinase activity and reduced biosynthesis of isoprenoid lipids required for the prenylation of small GTPase proteins. However, previous studies have not clearly shown any change in protein prenylation in patient cells under normal conditions. With lymphoblast cell lines from two compound heterozygous MKD patients, we used a highly sensitive in vitro prenylation assay, together with quantitative mass spectrometry, to reveal a subtle accumulation of unprenylated Rab GTPases in cells cultured for 3 days or more at 40 °C compared with 37 °C. This included a 200% increase in unprenylated Rab7A, Rab14 and Rab1A. Inhibition of sterol regulatory element-binding protein (SREBP) activation by fatostatin led to more pronounced accumulation of unprenylated Rab proteins in MKD cells but not parent cells, suggesting that cultured MKD cells may partially overcome the loss of isoprenoid lipids by SREBP-mediated upregulation of enzymes required for isoprenoid biosynthesis. Furthermore, while inhibition of Rho/Rac/Rap prenylation promoted the release of IL-1ß, specific inhibition of Rab prenylation by NE10790 had no effect in human peripheral blood mononuclear cells or human THP-1 monocytic cells. These studies demonstrate for the first time that mutations in mevalonate kinase can lead to a mild, temperature-induced defect in the prenylation of small GTPases, but that loss of prenylated Rab GTPases is not the cause of enhanced IL-1ß release in MKD.

Central Adrenal Insufficiency Is Not a Common Feature in CHARGE Syndrome: A Cross-Sectional Study in 2 Cohorts.

OBJECTIVE: To evaluate whether central adrenal insufficiency (CAI) is present in CHARGE (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital hypoplasia, and Ear abnormalities, including deafness) syndrome, a complex malformation disorder that includes central endocrine dysfunction. STUDY DESIGN: Two cross-sectional studies were performed in Dutch (September 2013-February 2015) and Australian (January 2012-January 2014) CHARGE syndrome clinics. Twenty-seven Dutch and 19 Australian patients (aged 16 months-18 years) with genetically confirmed CHARGE syndrome were included. The low-dose adrenocorticotropin (ACTH) test was used to assess CAI in the Dutch cohort. A peak cortisol response less than 18.1 µg/dL (500 nmol/L) was suspected for CAI, and a glucagon stimulation test was performed for confirmation. Australian patients were screened by single measurements of ACTH and cortisol levels. If adrenal dysfunction was suspected, a standard-dose ACTH test was performed. RESULTS: The low-dose ACTH test was performed in 23 patients (median age 8.4 [1.9-16.9] years). Seven patients showed an insufficient maximum cortisol level (10.3-17.6 µg/dL, 285-485 nmol/L), but CAI was confirmed by glucagon stimulation test in only 1 patient (maximum cortisol level 15.0 µg/dL, 415 nmol/L). In the Australian cohort, 15 patients (median age 9.1 [1.3-17.8] years) were screened, and none had CAI. CONCLUSIONS: CAI was not common in our cohorts, and routine testing of adrenal function in children with CHARGE syndrome is not indicated.

Respiratory manifestations and management in children with Common Variable Immunodeficiency.

Common variable immunodeficiency is an antibody deficiency that usually presents in childhood with recurrent sino-pulmonary infections. Diagnostic delay is frequent and thus respiratory morbidity is common, ranging from recurrent suppurative bronchitis to bronchiectasis. Immunoglobulin replacement therapy is the mainstay of treatment, whilst prophylactic antibiotic therapy and muco-ciliary clearance are additional treatment options. This review examines the diagnosis and management of respiratory issues in children with CVID.

Cryopyrin-associated periodic syndrome in Australian children and adults: Epidemiological, clinical and treatment characteristics.

AIM: Cryopyrin-associated periodic syndromes (CAPS) encapsulate three auto-inflammatory conditions, ranging in severity from mild (familial cold auto-inflammatory syndrome: FCAS), moderate (Muckle-Wells syndrome: MWS) and severe (neonatal onset multi-inflammatory disorder: NOMID). We aimed to describe the epidemiology, clinical features and outcomes of Australian children and adults with CAPS. METHODS: Patients were identified and clinical data collected through a questionnaire sent during 2012-2013 to clinicians reporting to the Australian Paediatric Surveillance Unit and subscribing to the Australasian Societies for Allergy/Immunology, Rheumatology and Dermatology. RESULTS: Eighteen cases of CAPS were identified (8 NOMID; 8 MWS, 2 FCAS); 12 in children <18 years of age. The estimated population prevalence of CAPS was 1 per million persons. Diagnostic delay was frequent, particularly in those with milder phenotypes (median diagnostic delay in MWS/FCAS 20.6 years compared with NOMID 2.1 years; P = 0.04). Common presenting features included urticaria (100%), periodic fever (78%), arthralgia (72%) and sensorineural hearing loss (61%). Almost all (90%) MWS patients had a family member similarly affected compared with none in the NOMID group (P = 0.004). A significant proportion of patients on anti-interleukin (IL)-1 therapy (n = 13) no longer had systemic inflammation. Only 50% with sensorineural hearing loss had hearing restored on anti-IL-1 therapy. CONCLUSIONS: Although CAPS are rare, patients often endured prolonged periods of systemic inflammation. This is despite almost all MWS patients having family members with similar symptoms and children with NOMID presenting with chronic infantile urticaria associated with multi-system inflammation. Hearing loss in NOMID/MWS was frequent, and reversible in only 50% of cases.

Non-IgE-mediated gastrointestinal food allergy.

Non-IgE-mediated gastrointestinal food-induced allergic disorders (non-IgE-GI-FAs) account for an unknown proportion of food allergies and include food protein-induced enterocolitis syndrome (FPIES), food protein-induced allergic proctocolitis (FPIAP), and food protein-induced enteropathy (FPE). Non-IgE-GI-FAs are separate clinical entities but have many overlapping clinical and histologic features among themselves and with eosinophilic gastroenteropathies. Over the past decade, FPIES has emerged as the most actively studied non-IgE-GI-FA, potentially because of acute and distinct clinical features. FPIAP remains among the common causes of rectal bleeding in infants, while classic infantile FPE is rarely diagnosed. The overall most common allergens are cow's milk and soy; in patients with FPIES, rice and oat are also common. The most prominent clinical features of FPIES are repetitive emesis, pallor, and lethargy; chronic FPIES can lead to failure to thrive. FPIAP manifests with bloody stools in well-appearing young breast-fed or formula-fed infants. Features of FPE are nonbloody diarrhea, malabsorption, protein-losing enteropathy, hypoalbuminemia, and failure to thrive. Non-IgE-GI-FAs have a favorable prognosis; the majority resolve by 1 year in patients with FPIAP, 1 to 3 years in patients with FPE, and 1 to 5 years in patients with FPIES, with significant differences regarding specific foods. There is an urgent need to better define the natural history of FPIES and the pathophysiology of non-IgE-GI-FAs to develop biomarkers and novel therapies.

Fifty years of allergy: 1965-2015.

The last 50 years in allergy could almost be considered the first 50 years. Over this time period, we have witnessed the emergence of allergy as a subspecialty, have seen and continue to observe a tremendous change in prevalence of allergic disease and have gained insight into the mechanisms that underlie allergic predisposition and disease manifestation. We have improved the care of children with many forms of allergic disease and now sit poised to be able to alter the natural history of allergic disease with the use of specific immunotherapy. There is much left to do in the next 50 years including understanding what underlies both the predisposition to atopic disease and its natural resolution and identifying the environmental cofactors involved in the 'allergic epidemic' and therefore targets for effective primary prevention.

Safety and clinical predictors of reacting to extensively heated cow's milk challenge in cow's milk-allergic children.

BACKGROUND: Many children with IgE-mediated allergy to cow's milk (CM) can tolerate CM in baked foods. OBJECTIVE: To define the clinical characteristics and severity of reactions to baked CM in children with CM allergy (CMA) at an oral food challenge (OFC). METHODS: Children with CMA presenting to a tertiary clinic from 2010 through 2013 with complete dietary CM avoidance were offered a baked CM OFC. Challenges were performed with incremental dosages to a total of 1 baked muffin. RESULTS: Seventy children with CMA underwent a baked CM OFC. Fifty-one children (73%) passed the OFC and successfully incorporated baked CM into their diet. Nineteen children (27%) reacted to their challenge. Of reactors, 4 (21%) developed anaphylaxis and required intramuscular adrenalin. Predictors of clinical reactivity to baked CM were asthma, asthma requiring preventer therapy, IgE-mediated clinical reactions to more than 3 food groups, and those with a history of CM anaphylaxis. CONCLUSION: This study identified factors that were predictors of clinical reactivity to baked CM in this cohort of children with CMA. These risk factors do not represent contradictions to a baked CM challenge but may allow for risk stratification of challenges. Given the potential for anaphylaxis, an OFC to baked CM should be done under medical supervision in those children with CMA who have been strictly avoiding all CM.