Background. Food allergies are a global burden causing severe clinical reactions including
fatal anaphylaxis. Peanuts are counted among the most potent elicitors involved in
IgE-mediated food allergies. Peanut allergy is a relevant disease model because of its
steadily increasing prevalence and poor prognosis of outgrowth. Clinical phenotypes of
peanut-allergic patients are highly variable. Patients might experience variable medical
symptoms (organs, severity, delay), threshold and cross-reactivity levels suggest. Reliable
in-vitro biomarker allowing to predict clinical reactivity and score the patients into
reaction endotypes are missing.
Most important peanut allergens have been studied as to their biomolecular properties
biological activities and allergenic potency. The pronounced protein stability of potent
peanut allergens is thought to contribute to the molecules' allergenicity. Upon ingestion,
food proteins are broken down, entering the human body via epithelial surfaces. The identity
and the fate of immunologically active allergen peptides after epithelial absorption remains
elusive. Beyond this, complex immune cascades take place during acute allergic episodes. How
immune cells, such as lymphocytes, orchestrate in patients with different clinical outcomes
(e.g., sensitivity, severity) still remains to be solved. Several studies have shown that the
composition and the diversity of the gut microbiota is relevant for shaping the immune
response to food proteins. The functional interaction between host and gut microbiome, in the
context of symptom development and phenotypic variations, is unexplored until today.
Aims. This project aims to explore putative biomarkers at various levels, at the level of
IgE-profiles, at the level of allergen absorption, at the level of scored basophil
reactivity, at the level of immune phenotypes and at the level of gut microbiome-host
interactions, by applying multiple omics technologies.
Partners. The Luxembourg Institute of Health (LIH), Department of Infection and Immunity
(DII; head Prof. M. Ollert) has the scientific project lead (Principal Investigator Dr. A.
Kuehn). Main clinical partners are Dr. F. Codreanu-Morel from the National Unit of
Immunology-Allergology, Centre Hospitalier (CHL), Luxembourg, as well as Prof. C.
Bindslev-Jensen from Odense Research Centre for Anaphylaxis (ORCA), Denmark. Partner for the
execution of the clinical part will be the Clinical and Epidemiological Investigation Center
(CIEC, LIH) headed by Dr. M. Gantenbein. The Integrated Biobank of Luxembourg (IBBL) will
prepare and store clinical samples until use. Clinical samples (blood, sera, plasma) will be
analyzed at DII, LIH. Stool samples will be investigated with the help of Prof. P. Wilmes
from the Systems Ecology research group, Luxembourg Centre for Systems Biomedicine (LCSB).
Project implementation. Food challenges (OFC) to peanut will be proceeded according to
official guidelines (European Academy of Allergy and Clinical Immunology, EAACI). Healthy
controls (N=10) will be split, half will receive a single food dose of up to 100 g of roasted
peanuts (open OFC) and the other half will be tested with up to 5 incremental doses
(double-blind placebo-controlled OFC) using the same doses as for allergic patients. For
single-dose OFC, blood samples from controls will be taken before the OFC and at 30 minutes,
at 60 minutes and at 120 minutes. Controls receiving 5 incremental allergen doses will be
subjected to blood sampling before the beginning of the OFC and 1 h after the end of the
challenge. As a further control arm in the study, allergenic food from animal origin will be
used in OFC. Further healthy controls (N=10) will receive either a single food dose of up to
200 g of cooked fish (open OFC) and the other half will be tested with up to 5 incremental
doses (double-blind placebo-controlled OFC). Doses in a range of 10 mg to 100 g of fish will
be selected for the blinded OFC with controls.
Allergic participants (N=30) will ingest incremental doses of peanuts. The OFC doses will be
in the range of 5 mg, 15 mg, 60 mg, 120 mg, 200 mg, 390 mg, 790 mg, 1,580 mg, 3,160 mg and
5,530 mg of roasted peanut. Maximum five doses will be selected from the above mentioned
ranges of peanut doses. Upon observation of allergic symptoms, the OFC will be stopped. If no
allergic symptoms occurred during a food challenge with five incremental doses, the patient
will be asked to participate in a second oral provocation (min. 14 days later) in order to
undergo a test with higher allergen doses. Blood samples from allergic study participants
will be drawn prior, during and after OFC (0, 60, 150, 180 minutes).
Stool samples from peanut-allergic participants (n=30) and healthy controls (n=20) will be
collected earliest 2 months after the food challenge. Prior sampling, participants should not
have used antibiotics within the last month, or have recent/ongoing gastrointestinal symptoms
(= diarrhea; Bristol scale 5-7) at the time of stool collection. Participants will receive a
collection kit at home, containing special sampling tubes, gloves and instructions. In
addition, patients are asked to record their food intake for the last 24 hours before
sampling.
Collected clinical samples will be pseudonymized at the clinical centers. A synonym list, as
part of the investigator file, containing the information on the participants' identity and
the corresponding pseudonym, will be available at the clinical center only (medical
investigators) and at CIEC. Personal data is protected under the regulation (EU) 2016/679 of
27 April 2016 on the protection of individuals with regard to the processing of personal data
(GDPR) and the law of 1 August 2018 on the organization of the National Data Protection
Commission and the General Data Protection Act.