Degree of hydrolysis is a poor predictor of the sensitizing capacity of whey- and casein-based hydrolysates in a Brown Norway rat model of cow's milk allergy.

The use of infant formulas (IFs) based on hydrolyzed cow's milk proteins to prevent cow's milk allergy (CMA) is highly debated. The risk of sensitization to milk proteins induced by IFs may be affected by the degree of hydrolysis (DH) as well as other physicochemical properties of the cow's milk-based protein hydrolysates within the IFs. The immunogenicity (specific IgG1 induction) and sensitizing capacity (specific IgE induction) of 30 whey- or casein-based hydrolysates with different physicochemical characteristics were compared using an intraperitoneal model of CMA in Brown Norway rats. In general, the whey-based hydrolysates demonstrated higher immunogenicity than casein-based hydrolysates, inducing higher levels of hydrolysate-specific and intact-specific IgG1. The immunogenicity of the hydrolysates was influenced by DH, peptide size distribution profile, peptide aggregation, nano-sized particle formation, and surface hydrophobicity. Yet, only the surface hydrophobicity was found to affect the sensitizing capacity of hydrolysates, as high hydrophobicity was associated with higher levels of specific IgE. The whey- and casein-based hydrolysates exhibited distinct immunological properties with highly diverse molecular composition and physicochemical properties which are not accounted for by measuring DH, which was a poor predictor of sensitizing capacity. Thus, future studies should consider and account for physicochemical characteristics when assessing the sensitizing capacity of cow's milk-based protein hydrolysates.

Food Allergy Education and Management in Early Learning and Childcare Centres: A Scoping Review on Current Practices and Gaps.

Anaphylaxis has occurred in preschools/schools yet there are no consistent food allergy (FA) management practices in early learning and childcare centres (ELCC) across jurisdictions. Presently, there are no reviews that have synthesized FA-related knowledge and management practices within ELCC. We aimed to perform a scoping review of FA management in ELCC, and report on perceived gaps or barriers. A PRISMA-ScR-guided search was conducted for North American, European and Australian articles in English/French in the OVID-MedLine, Scopus, and PsycInfo databases. Two independent reviewers screened the titles/abstracts of 2010 articles and full-text screened 77 articles; 15 of which were specifically related to ELCC. If the two reviewers could not agree to the relevance of a given study, a third reviewer provided guidance. This third reviewer also screened French articles. Thematic and descriptive reports of the studies were presented. We reported solely on pre-Coronavirus Disease pandemic ELCC studies. We included ten articles in this review, which provide evidence that ELCC staff have variable baseline knowledge, comprehension, experience, and practices in place to manage FA. ELCC staff also have limited FA-related training and experience regarding administration of epinephrine auto-injectors (EAI). Emergency Anaphylaxis Plans (EAP) were described in four studies. One study reported the parental influence on the site's food purchasing and FA management. Three studies provided educational interventions, which demonstrated increased and sustained FA-related knowledge and confidence post-intervention. Participants deemed the training beneficial and desired annual training and more FA resources to be available. Across jurisdictions, ELCC staff have provided care and administered EAI in emergencies, but training remained variable. Communication and care planning amongst ELCC staff, and parents, is crucial. Annual education, available EAI and EAPs are tools necessary for effectively managing emergencies.

Precision cut intestinal slices, a novel model of acute food allergic reactions.

BACKGROUND: Food allergy affects up to 10% of the pediatric population. Despite ongoing efforts, treatment options remain limited. Novel models of food allergy are needed to study response patterns downstream of IgE-crosslinking and evaluate drugs modifying acute events. Here, we report a novel human ex vivo model that displays acute, allergen-specific, IgE-mediated smooth muscle contractions using precision cut intestinal slices (PCIS). METHODS: PCIS were generated using gut tissue samples from children who underwent clinically indicated surgery. Viability and metabolic activity were assessed from 0 to 24 h. Distribution of relevant cell subsets was confirmed using single nucleus RNA sequencing. PCIS were passively sensitized using plasma from peanut allergic donors or peanut-sensitized non-allergic donors, and exposed to various stimuli including serotonin, histamine, FcɛRI-crosslinker, and food allergens. Smooth muscle contractions and mediator release functioned as readouts. A novel program designed to measure contractions was developed to quantify responses. The ability to demonstrate the impact of antihistamines and immunomodulation from peanut oral immunotherapy (OIT) was assessed. RESULTS: PCIS viability was maintained for 24 h. Cellular distribution confirmed the presence of key cell subsets including mast cells. The video analysis tool reliably quantified responses to different stimulatory conditions. Smooth muscle contractions were allergen-specific and reflected the clinical phenotype of the plasma donor. Tryptase measurement confirmed IgE-dependent mast cell-derived mediator release. Antihistamines suppressed histamine-induced contraction and plasma from successful peanut OIT suppressed peanut-specific PCIS contraction. CONCLUSION: PCIS represent a novel human tissue-based model to study acute, IgE-mediated food allergy and pharmaceutical impacts on allergic responses in the gut.

Platelet Activating Factor (PAF): A Mediator of Inflammation.

Platelet-activating factor (PAF) is a phospholipid-derived mediator with an established role in multiple inflammatory states. PAF is synthesized and secreted by multiple cell types and is then rapidly hydrolyzed and degraded to an inactive metabolite, lyso-PAF, by the enzyme PAF acetylhydrolase. In addition to its role in platelet aggregation and activation, PAF contributes to allergic and nonallergic inflammatory diseases such as anaphylaxis, sepsis, cardiovascular disease, neurological disease, and malignancy as demonstrated in multiple animal models and, increasingly, in human disease states. Recent research has demonstrated the importance of the PAF pathway in multiple conditions including the prediction of severe pediatric anaphylaxis, effects on blood-brain barrier permeability, effects on reproduction, ocular diseases, and further understanding of its role in cardiovascular risk. Investigation of PAF as both a biomarker and a therapeutic target continues because of the need for directed management of inflammation. Collectively, studies have shown that therapies focused on the PAF pathway have the potential to provide targeted and effective treatments for multiple inflammatory conditions.

Homozygous duplication identified by whole genome sequencing causes LRBA deficiency.

In more than one-third of primary immunodeficiency (PID) patients, extensive genetic analysis including whole-exome sequencing (WES) fails to identify the genetic defect. Whole-genome sequencing (WGS) is able to detect variants missed by other genomics platforms, enabling the molecular diagnosis of otherwise unresolved cases. Here, we report two siblings, offspring of consanguineous parents, who experienced similar severe events encompassing early onset of colitis, lymphoproliferation, and hypogammaglobulinemia, typical of lipopolysaccharide-responsive and beige-like anchor (LRBA) or cytotoxic T lymphocyte antigen 4 (CTLA4) deficiencies. Gene-panel sequencing, comparative genomic hybridization (CGH) array, and WES failed to reveal a genetic aberration in relevant genes. WGS of these patients detected a 12.3 kb homozygous tandem duplication that was absent in control cohorts and is predicted to disrupt the reading frame of the LRBA gene. The variant was validated by PCR and Sanger sequencing, demonstrating the presence of the junction between the reference and the tandem-duplicated sequence. Droplet digital PCR (ddPCR) further confirmed the copy number in the unaffected parents (CN = 3, heterozygous) and affected siblings (CN = 4, homozygous), confirming the expected segregation pattern. In cases of suspected inherited immunodeficiency, WGS may reveal a mutation when other methods such as microarray and WES analysis failed to detect an aberration.

Safety of administration of BNT162b2 mRNA (Pfizer-BioNTech) COVID-19 vaccine in youths and young adults with a history of acute lymphoblastic leukemia and allergy to PEG-asparaginase.

Vaccinationis a critical tool in the prevention of COVID-19 infection for individuals and for communities. The mRNA vaccines contain polyethylene glycol (PEG) as a stabilizer. Currently, in North America, only the BNT162b2 (Pfizer-BioNTech) mRNA vaccine is approved for individuals aged 12-17. Most patients treated with contemporary regimens for acute lymphoblastic leukemia receive PEG-asparaginase (PEG-ASNase) and 10%-30% will develop allergic reactions. Optimizing access and safety for vaccine administration for these patients is critical. This report describes a process developed to support COVID vaccination in a cohort of adolescents and young adults with a history of PEG-ASNase allergy.

Production of allergen-specific immunotherapeutic agents for the treatment of food allergy.

Allergen-specific immunotherapy (IT) is emerging as a viable avenue for the treatment of food allergies. Clinical trials currently investigate raw or slightly processed foods as therapeutic agents, as trials using food-grade agents can be performed without the strict regulations to which conventional drugs are subjected. However, this limits the ability of standardization and may affect clinical trial outcomes and reproducibility. Herein, we provide an overview of methods used in the production of immunotherapeutic agents for the treatment of food allergies, including processed foods, allergen extracts, recombinant allergens, and synthetic peptides, as well as the physical and chemical processes for the reduction of protein allergenicity. Commercial interests currently favor producing standardized drug-grade allergen extracts for therapeutic use, and clinical trials are ongoing. In the near future, recombinant production could replace purification strategies since it allows the manufacturing of pure, native allergens or sequence-modified allergens with reduced allergenicity. A recurring issue within this field is the inadequate reporting of production procedures, quality control, product physicochemical characteristics, allergenicity, and immunological properties. This information is of vital importance in assessing therapeutic standardization and clinical safety profile, which are central parameters for the development of future therapeutic agents.

Primary immunodeficiencies and their associated risk of malignancies in children: an overview.

Primary immunodeficiency disorders represent a heterogeneous spectrum of diseases, predisposing to recurrent infections, allergy, and autoimmunity. While an association between primary immunodeficiency disorders and increased risk of cancer has been suggested since the 1970s, renewed attention has been given to this topic in the last decade, largely in light of the availability of large registries as well as advances in next generation sequencing. In this narrative review, we will give an insight of the primary immunodeficiencies that are commonly responsible for the greater number of cancers in the primary immunodeficiency disorders population. We will describe clinical presentations, underlying genetic lesions (if known), molecular mechanisms for carcinogenesis, as well as some management considerations. We will also comment on the future directions and challenges related to this topic.Conclusion: The awareness of the association between several primary immunodeficiencies and cancer is crucial to provide the best care for these patients.What is Known: • Patients with primary immunodeficiency have an increased risk of malignancy. The type of malignancy is highly dependent on the specific primary immunodeficiency disorder.What is New: • Survival in patients with primary immunodeficiency disorders has been improving, and conversely also their lifetime risk of malignancy. • International collaboration and multinational registries are needed to improve our knowledge and therapeutic strategies.

Prevalence and Clinical Features of Inflammatory Bowel Diseases Associated With Monogenic Variants, Identified by Whole-Exome Sequencing in 1000 Children at a Single Center.

BACKGROUND & AIMS: A proportion of infants and young children with inflammatory bowel diseases (IBDs) have subtypes associated with a single gene variant (monogenic IBD). We aimed to determine the prevalence of monogenic disease in a cohort of pediatric patients with IBD. METHODS: We performed whole-exome sequencing analyses of blood samples from an unselected cohort of 1005 children with IBD, aged 0-18 years (median age at diagnosis, 11.96 years) at a single center in Canada and their family members (2305 samples total). Variants believed to cause IBD were validated using Sanger sequencing. Biopsies from patients were analyzed by immunofluorescence and histochemical analyses. RESULTS: We identified 40 rare variants associated with 21 monogenic genes among 31 of the 1005 children with IBD (including 5 variants in XIAP, 3 in DOCK8, and 2 each in FOXP3, GUCY2C, and LRBA). These variants occurred in 7.8% of children younger than 6 years and 2.3% of children aged 6-18 years. Of the 17 patients with monogenic Crohn's disease, 35% had abdominal pain, 24% had nonbloody loose stool, 18% had vomiting, 18% had weight loss, and 5% had intermittent bloody loose stool. The 14 patients with monogenic ulcerative colitis or IBD-unclassified received their diagnosis at a younger age, and their most predominant feature was bloody loose stool (78%). Features associated with monogenic IBD, compared to cases of IBD not associated with a single variant, were age of onset younger than 2 years (odds ratio [OR], 6.30; P = .020), family history of autoimmune disease (OR, 5.12; P = .002), extra-intestinal manifestations (OR, 15.36; P < .0001), and surgery (OR, 3.42; P = .042). Seventeen patients had variants in genes that could be corrected with allogeneic hematopoietic stem cell transplantation. CONCLUSIONS: In whole-exome sequencing analyses of more than 1000 children with IBD at a single center, we found that 3% had rare variants in genes previously associated with pediatric IBD. These were associated with different IBD phenotypes, and 1% of the patients had variants that could be potentially corrected with allogeneic hematopoietic stem cell transplantation. Monogenic IBD is rare, but should be considered in analysis of all patients with pediatric onset of IBD.

A Toddler With Treatment-Resistant Iron Deficiency Anemia.

A 19-month-old girl with a history of asthma and atopic dermatitis presented to her pediatrician because of parental concerns of pallor and fatigue. On dietary history, it was discovered that she was a picky eater and consumed 26 oz of homogenous milk daily. Her physical examination was unremarkable aside from pallor, and both her height and weight plotted between the 50th and 75th percentile for age. Therefore, she was investigated for iron deficiency anemia and indeed her blood work was consistent. Despite appropriate iron supplementation and dietary milk restriction, there was no improvement in her hemoglobin or iron studies. Our expert panel examines the case and offers a differential diagnosis for a child presenting with treatment-resistant iron deficiency anemia.

Autosomal Recessive Agammaglobulinemia Due to a Homozygous Mutation in PIK3R1.

The role of class IA phosphoinositide 3 kinases (PI3Ks) in immune function and regulation continues to expand with the identification of greater numbers of genetic variants. This case report is the second reported case of a homozygous premature stop codon within the PIK3R1 gene leading to autosomal recessive agammaglobulinemia. The proband, born to consanguineous parents, presented at 10 months of age with a history of oropharyngeal petechiae and bleeding from the mouth, gums, and tear ducts. Initial investigations revealed thrombocytopenia, neutropenia and the absence of B cells. Further genetic testing via a custom next-generation sequencing panel confirmed the presence of a homozygous mutation in PIK3R1, c.901 C>T, a premature stop codon at amino acid position 301. Given their many roles in immune regulation, recessive mutations in the PlK3R1 gene should be considered in infants presenting with hypogammaglobulinemia or agammaglobulinemia, particularly in the setting of parental consanguinity.

Loss of the Arp2/3 complex component ARPC1B causes platelet abnormalities and predisposes to inflammatory disease.

Human actin-related protein 2/3 complex (Arp2/3), required for actin filament branching, has two ARPC1 component isoforms, with ARPC1B prominently expressed in blood cells. Here we show in a child with microthrombocytopenia, eosinophilia and inflammatory disease, a homozygous frameshift mutation in ARPC1B (p.Val91Trpfs*30). Platelet lysates reveal no ARPC1B protein and greatly reduced Arp2/3 complex. Missense ARPC1B mutations are identified in an unrelated patient with similar symptoms and ARPC1B deficiency. ARPC1B-deficient platelets are microthrombocytes similar to those seen in Wiskott-Aldrich syndrome that show aberrant spreading consistent with loss of Arp2/3 function. Knockout of ARPC1B in megakaryocytic cells results in decreased proplatelet formation, and as observed in platelets from patients, increased ARPC1A expression. Thus loss of ARPC1B produces a unique set of platelet abnormalities, and is associated with haematopoietic/immune symptoms affecting cell lineages where this isoform predominates. In agreement with recent experimental studies, our findings suggest that ARPC1 isoforms are not functionally interchangeable.

Primary immunodeficiencies associated with eosinophilia.

BACKGROUND: Eosinophilia is not an uncommon clinical finding. However, diagnosis of its cause can be a dilemma once common culprits, namely infection, allergy and reactive causes are excluded. Primary immunodeficiency disorders (PID) are among known differentials of eosinophilia. However, the list of PIDs typically reported with eosinophilia is small and the literature lacks an inclusive list of PIDs which have been reported with eosinophilia. This motivated us to review the literature for all PIDs which have been described to have elevated eosinophils as this may contribute to an earlier diagnosis of PID and further the understanding of eosinophilia. METHODS: A retrospective PubMed, and Google Scholar search using the terms "eosinophilia" and "every individual PID" as classified by Expert Committee of the International Union of Immunological Societies with the limit of the English language was performed. Results were assessed to capture case(s) which reported eosinophilia in the context of PID conditions. Absolute eosinophil counts (AEC) were retrieved from manuscripts whenever reported. RESULTS: In addition to the typical PID conditions described with eosinophilia, we document that MHC class II deficiency, CD3γ deficiency, STAT1 deficiency (AD form), Kostmann disease, cyclic neutropenia, TCRα deficiency, Papillon-Lefevre syndrome, CD40 deficiency, CD40L deficiency, anhidrotic ectodermal dysplasia with immune deficiency, ataxia-telangiectasia, common variable immunodeficiency disorders (CVID), Blau syndrome, CARD9 deficiency, neonatal onset multisystem inflammatory disease or chronic infantile neurologic cutaneous and articular syndrome (NOMID/CINCA), chronic granulomatous disease, MALT1 deficiency and Roifman syndrome have been noted to have elevated eosinophils. Severe eosinophilia (>5.0 × 10(9)/L) was reported in Omenn syndrome, Wiskott Aldrich syndrome, ADA deficiency, autoimmune lymphoproliferative syndrome, immunodysregulation polyendocrinopathy enteropathy X-linked, STAT3 deficiency, DOCK8 deficiency, CD40 deficiency, MHC II deficiency, Kostmann disease, Papillon-Lefevre syndrome, and CVID. CONCLUSIONS: This literature review shows that there is an extensive list of PIDs which have been reported with eosinophilia. This list helps clinicians to consider an extended differential diagnoses when tasked with exclusion of PID as a cause for eosinophilia.

A child with autoimmune polyendocrinopathy candidiasis and ectodermal dysplasia treated with immunosuppression: a case report.

INTRODUCTION: Common features of autoimmune polyendocrinopathy-candidiasis-ectodermal dysplasia include candidiasis, hypoparathyroidism and hypoadrenalism. The initial manifestation of autoimmune polyendocrinopathy-candidiasis-ectodermal dysplasia may be autoimmune hepatitis, keratoconjunctivitis, frequent fever with or without a rash, chronic diarrhea, or different combinations of these with or without oral candidiasis. CASE PRESENTATION: We discuss a profoundly affected 2.9-year-old Caucasian girl of Western European descent with a dramatic response to immunosuppression (initially azathioprine and oral steroids, and then subsequently mycophenolate mofetil monotherapy). At four years of follow-up, her response to mycophenolate mofetil is excellent. CONCLUSION: The clinical features of autoimmune polyendocrinopathy-candidiasis-ectodermal dysplasia may continue for years before some of the more common components appear. In such cases, it may be life-saving to diagnose autoimmune polyendocrinopathy-candidiasis-ectodermal dysplasia and commence therapy with immunosuppressive agents. The response of our patient to immunosuppression with mycophenolate mofetil has been dramatic. It is possible that other patients with this condition might also benefit from immunosuppression.