Title Page:Article Type: Letter to the EditorTitle: Anaphylaxis to a blood feeding leechAuthors: Carmen H. Li MSc1,2*, Maggie Jiang MD3*, Gabriele Gadermaier PhD4, Sebastian Kvist PhD5,6,7 Julia E. M. Upton MD8,9, Xiaojun Yin PhD1, Jennifer A. Hoang MSc MDS1,10, Mikhail Monteiro BSc1, Lisa Hung PhD1,10, Akash Kothari MSc1,2, Theo J. Moraes MD PhD1,9, Peter Vadas MD PhD3,10**, Thomas Eiwegger MD1,10,11,12***Co-first author**Co-senior author(1) Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, ON, Canada(2) Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada(3) Division of Clinical Immunology and Allergy, St. Michael’s Hospital(4) Department of Biosciences and Medical Biology, Paris Lodron University Salzburg, Salzburg, Austria(5) Department of Ecology and Evolutionary Biology, University of Toronto, ON, Canada(6) Department of Invertebrate Zoology, Royal Ontario Museum, Toronto, ON, Canada(7) Swedish Museum of Natural History, Stockholm, Sweden(8) Division of Immunology and Allergy, Food Allergy and Anaphylaxis Program, The Hospital for Sick Children(9) Department of Pediatrics, University of Toronto, Toronto, ON, Canada(10) Department of Immunology, Temerty Faculty of Medicine, University of Toronto, Ontario, Toronto, Canada(11) Karl Landsteiner University of Health Sciences, Krems, Austria(12) Department of Pediatric and Adolescent Medicine, University Hospital St. Pölten, St. Pölten, AustriaCorrespondence:  Thomas Eiwegger, MDChair, Department of Pediatric and Adolescent MedicineUniversity Hospital St. PöltenDunant-Platz 1, 3100 St. Pölten, AustriaEmail: [email protected].: +43 2742-9004-11740

Background: Food allergy affects up to 8% 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 0-24h. Distribution of relevant cell subsets was confirmed using single cell nuclear 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 24h. 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.

Article Type : Letter to the EditorTitle : Whole blood high dimensional single cell functional profiling of basophils in peanut allergy

Article Type: Letter to the EditorTitle : The impact of maternal-fetal omalizumab transfer on peanut-specific responses in an ex vivo placental perfusion model

Article Type: News and Views: Groundbreaking Discoveries in ImmunologyTitle: Emollients for the prevention of atopic dermatitisAuthors: Akash Kothari1(https://orcid.org/0000-0003-1980-161X), Arielle Locke2,Thomas Eiwegger1,3,4(https://orcid.org/0000-0002-2914-7829)1Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada2Department of Medicine, National University of Ireland, Galway, Ireland3Division of Immunology and Allergy, Food Allergy and Anaphylaxis Program, The Department of Pediatrics, Hospital for Sick Children, Toronto, Ontario, Canada4Department of Immunology, Faculty of Medicine, University of Toronto, Toronto, Ontario, CanadaCorrespondence to: Thomas Eiwegger, MD, Division of Immunology and Allergy, Food Allergy and Anaphylaxis Program, The Department of Paediatrics, Hospital for Sick Children, 555 University Ave, Toronto, Canada, E-mail: [email protected], Tel.: +1 416-813-7654 ext. 1862Conflicts of Interest: AK and AL have nothing to disclose. TE reports to act as local PI for company sponsored trials by DBV and sub-investigator for Regeneron, holds grants from Innovation Fund Denmark, CIHR outside the submitted work. He is Co-Investigator or scientific lead in three investigator initiated oral immunotherapy trials supported by the Food Allergy and Anaphylaxis Program SickKids and serves as associate editor for Allergy. He/his lab received unconditional/in-kind contributions from Macro Array Diagnostics and an unrestricted grant from ALK. He holds advisory board roles for ALK.Financial support: This work was supported by The Hospital for Sick Children, The Food Allergy and Anaphylaxis Program at The Hospital for Sick Children, and The Dr Lorus J And Dr Margery J Milne Scholarship from Victoria University at the University of Toronto.Statement of Author Contribution: All authors critically reviewed the original articles (references 6 and 7) and wrote the News & Views: Groundbreaking discoveries in Immunology article. All authors contributed, revised, edited, and approved the final version of the manuscript as submitted and agreed to be accountable for all aspects of the work.Keywords: emollient, atopic eczema, infancyAbbreviations : food allergy, FA; filaggrin gene, FLG; atopic dermatitis, AD; transepidermal water loss, TEWL; Barrier Enhancement for Eczema Prevention, BEEP; Preventing Atopic Dermatitis and Allergies, PreventADALL