Eosinophilia and wheeze: thinking beyond asthma.

Primary idiopathic hypereosinophilic syndrome is a rare condition that can cause end-organ damage in multiple systems. The advent of targeted monoclonal antibodies, such as mepolizumab, provides a safe and effective steroid-sparing treatment. https://bit.ly/4bgDP1u.

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.

Increased core body temperature exacerbates defective protein prenylation in mouse models of mevalonate kinase deficiency.

Mevalonate kinase deficiency (MKD) is characterized by recurrent fevers and flares of systemic inflammation, caused by biallelic loss-of-function mutations in MVK. The underlying disease mechanisms and triggers of inflammatory flares are poorly understood because of the lack of in vivo models. We describe genetically modified mice bearing the hypomorphic mutation p.Val377Ile (the commonest variant in patients with MKD) and amorphic, frameshift mutations in Mvk. Compound heterozygous mice recapitulated the characteristic biochemical phenotype of MKD, with increased plasma mevalonic acid and clear buildup of unprenylated GTPases in PBMCs, splenocytes, and bone marrow. The inflammatory response to LPS was enhanced in compound heterozygous mice and treatment with the NLRP3 inflammasome inhibitor MCC950 prevented the elevation of circulating IL-1ß, thus identifying a potential inflammasome target for future therapeutic approaches. Furthermore, lines of mice with a range of deficiencies in mevalonate kinase and abnormal prenylation mirrored the genotype-phenotype relationship in human MKD. Importantly, these mice allowed the determination of a threshold level of residual enzyme activity, below which protein prenylation is impaired. Elevated temperature dramatically but reversibly exacerbated the deficit in the mevalonate pathway and the defective prenylation in vitro and in vivo, highlighting increased body temperature as a likely trigger of inflammatory flares.

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.

A Response Surface Methodology (RSM) Approach for Optimizing the Attenuation of Human IgE-Reactivity to ß-Lactoglobulin (ß-Lg) by Hydrostatic High Pressure Processing.

The response surface methodology (RSM) and central composite design (CCD) technique were used to optimize the three key process parameters (i.e., pressure, temperature and holding time) of the high-hydrostatic-pressure (HHP) processing either standalone or combined with moderate thermal processing to modulate molecular structures of ß-lactoglobulin (ß-Lg) and α-lactalbumin (α-La) with reduced human IgE-reactivity. The RSM model derived for HHP-induced molecular changes of ß-Lg determined immunochemically showed that temperature (temp), pressure (p2) and the interaction between temperature and time (t) had statistically significant effects (p < 0.05). The optimal condition defined as minimum (ß-Lg specific) IgG-binding derived from the model was 505 MPa at 56 °C with a holding time of 102 min (R2 of 0.81 and p-value of 0.01). The validation carried at the optimal condition and its surrounding region showed that the model to be underestimating the ß-Lg structure modification. The molecular change of ß-Lg was directly correlated with HHP-induced dimerization in this study, which followed a quadratic equation. The ß-Lg dimers also resulted in the undetectable human IgE-binding.

Increased Rates of Peanut and Tree Nut Aspiration as a Possible Consequence of Allergy Prevention by Early Introduction.

BACKGROUND: Pediatric airway foreign bodies (FBs) are a surgical emergency, and peanuts and tree nuts (PN/TNs) can pose a significant aspiration risk in young children. In 2015, the Learning Early About Peanut allergy (LEAP) trial established that early introduction of peanuts in high-risk infants reduced the risk of developing a peanut allergy. Infant feeding guidelines were subsequently modified to actively encourage the introduction of allergenic foods for all infants. The impact of this shift in feeding advice on the incidence of PN/TN inhalation has not been previously studied. OBJECTIVE: To determine the incidence of PN/TN inhalation presentations to a quaternary pediatric hospital between 2008 and 2018. METHODS: A retrospective cohort study of children who were diagnosed with an airway FB by rigid bronchoscopy. RESULTS: There were 200 cases of FB inhalation (35% PN/TN, 34% other foods, and 31% inorganic material). There was a rise in the total incidence of FB inhalation over the study period (incidence ratio rate [IRR], 1.09; P < .001). The rise was due to PN/TN (IRR, 1.16; P < .002) and other food inhalation (IRR, 1.12; P = .01), with no significant increase in inorganic FB aspiration (IRR, 1; P = .94). Between pre-LEAP (2008-2014) and post-LEAP (2015-2018) periods, there was a trebling, doubling, and no increase in the rate of PN/TN, other food, and inorganic FB inhalation, respectively. CONCLUSIONS: Since the publication of the LEAP study, there has been a rise in PN/TN and other hard solid food inhalation at our institution. This study highlights the urgent need to engage the public to promote safe introduction of hard foods in young children.

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.

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.

Added Diagnostic Value of Peanut Component Testing: A Cross-Sectional Study in Australian Children.

BACKGROUND: Peanut components are widely used in clinical practice; however, their utility to predict challenge outcome in the Australian children, outside of infants, is not well studied. OBJECTIVE: Can peanut component testing predict outcome of challenge in peanut-allergic children. METHODS: All children attending peanut challenges, regardless of previous allergic reactions to peanut or sensitization (skin prick test or peanut IgE) alone, were recruited. Serum collected before the challenge was analyzed for peanut IgE and Ara h 1, 2, 3, 6, 8, and 9 (ImmunoCap). RESULTS: Of the 222 children recruited, 89 (40%) were allergic on oral food challenge. Ara h 2 and 6 performed similarly to peanut IgE and skin prick test in predicting challenge outcome (area under the curve, 0.84-0.87). No baseline clinical characteristics, including past history, predicted challenge outcome. By logistic regression, degree of polysensitization to Ara h 1, 2, or 3 increased the odds of allergic reaction at oral food challenge at 0.35 and 1.0 kUA/L cutoff levels (P < .001 for both). All 11 children sensitized (>0.35 kUA/L) to Ara h 1, 2, and 3 reacted to peanut challenge. Degree of polysensitization at more than 1.0 kUA/L was associated with a lower cumulative eliciting dose (P = .016) and with severity of allergic reaction on challenge (P = .007). CONCLUSIONS: In our cohort, sensitization to the combination of Ara h 1, 2, and 3 was highly predictive of peanut allergy. Overall, only Ara h 2 as individual component most correlated with severity of reaction at challenge and adrenaline use. Ara h 8 and 9 were not useful in predicting challenge outcome.

Food Protein-Induced Enterocolitis Syndrome.

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy that manifests with projectile, repetitive emesis that can be followed by diarrhea and may be accompanied by lethargy, hypotonia, hypothermia, hypotension, and metabolic derangements. FPIES usually starts in infancy although onset at older ages is being increasingly recognized. FPIES is not rare, with the cumulative incidence of FPIES in infants estimated to be 0.015% to 0.7%, whereas the population prevalence in the US infants was 0.51%. FPIES diagnosis is challenging and might be missed because of later (1-4 hours) onset of symptoms after food ingestion, lack of typical allergic skin and respiratory symptoms, and food triggers that are perceived to be hypoallergenic. Diagnosis is based on the recognition of symptoms because there are no biomarkers of FPIES. The pathophysiology remains obscure although activation of the innate immune compartment has been detected. Management relies of avoidance of food triggers, treatment of accidental exposures, and periodic re-evaluations with supervised oral food challenges to monitor for resolution. There are no strategies to accelerate development of tolerance in FPIES. Here we review the most important current concepts in epidemiology, pathophysiology, diagnosis, and management of FPIES.

Defective Protein Prenylation in a Spectrum of Patients With Mevalonate Kinase Deficiency.

The rare autoinflammatory disease mevalonate kinase deficiency (MKD, which includes HIDS and mevalonic aciduria) is caused by recessive, pathogenic variants in the MVK gene encoding mevalonate kinase. Deficiency of this enzyme decreases the synthesis of isoprenoid lipids and thus prevents the normal post-translational prenylation of small GTPase proteins, which then accumulate in their unprenylated form. We recently optimized a sensitive assay capable of detecting unprenylated Rab GTPase proteins in peripheral blood mononuclear cells (PBMCs) and showed that this assay distinguished MKD from other autoinflammatory diseases. We have now analyzed PBMCs from an additional six patients with genetically-confirmed MKD (with different compound heterozygous MVK genotypes), and compared these with PBMCs from three healthy volunteers and four unaffected control individuals heterozygous for the commonest pathogenic variant, MVKV377I . We detected a clear accumulation of unprenylated Rab proteins, as well as unprenylated Rap1A by western blotting, in all six genetically-confirmed MKD patients compared to heterozygous controls and healthy volunteers. Furthermore, in the three subjects for whom measurements of residual mevalonate kinase activity was available, enzymatic activity inversely correlated with the extent of the defect in protein prenylation. Finally, a heterozygous MVKV377I patient presenting with autoinflammatory symptoms did not have defective prenylation, indicating a different cause of disease. These findings support the notion that the extent of loss of enzyme function caused by biallelic MVK variants determines the severity of defective protein prenylation, and the accumulation of unprenylated proteins in PBMCs may be a sensitive and consistent biomarker that could be used to aid, or help rule out, diagnosis of MKD.

Differentiating Acute Food Protein-Induced Enterocolitis Syndrome From Its Mimics: A Comparison of Clinical Features and Routine Laboratory Biomarkers.

BACKGROUND: Food protein-induced enterocolitis syndrome (FPIES) is frequently misdiagnosed and subject to diagnostic delay. Profuse vomiting, the cardinal feature of acute FPIES, may occur in more common pediatric disorders such as gastroenteritis and sepsis. OBJECTIVES: We sought to determine differentiating features at acute presentation between FPIES, gastroenteritis, and sepsis in young children presenting to an emergency department (ED) with profuse vomiting. METHODS: We conducted a retrospective case-control study of children aged 6 months to 4 years with a diagnosis of acute FPIES who had presented to ED and compared the clinical features, vital signs, and routine laboratory studies of this cohort to similarly aged children presenting to ED with vomiting diagnosed with bacterial/viral gastroenteritis or bacterial sepsis. RESULTS: A total of 181 acute FPIES ED presentations were compared with 55 gastroenteritis and 36 bacterial sepsis ED presentations. Children with FPIES were more likely to present with lethargy, floppiness, and pallor. Compared with children with FPIES, children with sepsis were likely to present with fever, tachycardia, tachypnea, and diarrhea, whereas those with gastroenteritis were likely to present with fever, diarrhea, and blood in stools. Normal C-reactive protein (CRP), leucocytosis, lymphocytosis, thrombocytosis, low MPV, and an elevated albumin/globulin ratio were more commonly seen in FPIES than in sepsis or gastroenteritis. No other clinical or laboratory markers examined reliably distinguished between the 3 disease groups. CONCLUSIONS: In the young vomiting child, lethargy, floppiness, pallor without fever, and normal CRP should alert clinicians to a possible diagnosis of FPIES. In contrast, a highly elevated CRP is not a feature of FPIES, and in such cases an alternative diagnosis must be considered.

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.

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.