Positive Health Online

Abstract

HUFNAGL and COLLEAGUES, 1 The Interuniversity Messerli Research Institute of the University of Veterinary Medicine Vienna, Medical University Vienna and University Vienna, Vienna, Austria; 2 University of Cincinnati College of Medicine, Ohio, USA; 3 Childrens Hospital Bambino Gesù, Rome, Italy; 4 Genomics Core Facility, VetCore, University of Veterinary Medicine, Vienna, Austria; 5 Center for Anthropogenic Infections, Division for Public Health, Austrian Agency for Health and Food Safety, Vienna, Austria; 6 Department of Anesthesiology, General Intensive Care and Pain Medicine, Medical University of Vienna, Vienna, Austria; RAIC Laboratory 13C1, Medical University of Vienna, Vienna, Austria; 7 Department of Natural Systems and Resources, ETSI Montes, Technical University of Madrid, and Centro de Biotecnología y Genómica de Plantas (CBGP) UPM-INIA, Campus de Montegancedo UPM, Madrid, Spain; 8 The Interuniversity Messerli Research Institute of the University of Veterinary Medicine Vienna, Medical University Vienna and University Vienna, Vienna, Austria. erika.jensen-jarolim@meduniwien.ac.at ;           9 Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University Vienna, Vienna, Austria. erika.jensen-jarolim@meduniwien.ac.at  investigated whether Bos d 5 when loaded with the active vitamin A metabolite retinoic acid (RA), would elicit differential immune responses compared to the unloaded state.

Background

The major cow's milk allergen Bos d 5 belongs to the lipocalin protein family, with an intramolecular pocket for hydrophobic ligands.

Methodology

We investigated whether Bos d 5 when loaded with the active vitamin A metabolite retinoic acid (RA), would elicit differential immune responses compared to the unloaded state.

Results

By in silico docking an affinity energy of -7.8 kcal/mol was calculated for RA into Bos d 5. Loading of RA to Bos d 5 could be achieved in vitro, as demonstrated by ANS displacement assay, but had no effect on serum IgE binding in tolerant or challenge-positive milk allergic children. Bioinformatic analysis revealed that RA binds to the immunodominant T-cell epitope region of Bos d 5. In accordance, Bos d 5 significantly suppressed the CD3+ CD4+ cell numbers, proliferative response and IL-10, IL-13 and IFN-γ secretion from stimulated human PBMCs only when complexed with RA. This phenomenon was neither associated with apoptosis of T-cells nor with the activation of Foxp3+ T-cells, but correlated likely with enhanced stability to lysosomal digestion due to a predicted overlap of Cathepsin S cleavage sites with the RA binding site.

Conclusion

Taken together, proper loading of Bos d 5 with RA may suppress its immunogenicity and prevent its allergenicity. Conflict of interest statement. The authors declare that they have no competing interests.

References

Karin Hufnagl  1 , Debajyoti Ghosh  2 , Stefanie Wagner  1 , Alessandro Fiocchi  3 , Lamia Dahdah  3 , Rodolfo Bianchini  1 , Nina Braun  1 , Ralf Steinborn  4 , Martin Hofer  4 , Marion Blaschitz  5 , Georg A Roth  6 , Gerlinde Hofstetter  1 , Franziska Roth-Walter  1 , Luis F Pacios  7 , Erika Jensen-Jarolim  8   9. Retinoic acid prevents immunogenicity of milk lipocalin Bos d 5 through binding to its immunodominant T-cell epitope  Sci Rep.  ;8(1):1598. doi: 10.1038/s41598-018-19883-0. Jan 25 2018.