(J-396) Allergen-Encapsulating Nanoparticles Reduce Human Mast Cell Survival and Degranulation in Food Allergy

Friday, October 13, 2023

3:30 PM – 4:30 PM PDT

Location: Exhibit Hall - Row J - Poster # 396

Presenting Author(s)

AA

Amogh Angadi (he/him/his)

Undergraduate Student Research Assistant
University of Michigan, Michigan, United States

Co-Author(s)

MS

Michael Saunders

Graduate Student Research Assistant
University of Michigan, United States

Primary Investigator(s)

LS

Lonnie D. Shea

Steven A. Goldstein Collegiate Professor
University of Michigan, United States

Introduction:: Food allergy is characterized by an inappropriate immune response to a food allergen and is a growing concern in the developed world1. Current treatments focus on allergen-specific immunotherapy, which relies on gradually increasing the dosage of allergen the patient receives to raise the threshold needed to trigger symptoms2. The Shea lab has developed allergen-encapsulated nanoparticles (aeNPs) that offer a safe way to desensitize individuals with food allergies by directly targeting key immune cell populations and minimizing the risk of an adverse reaction through masked allergen delivery1. Our preliminary data show that in allergic mice, our aeNPs associate directly with mast cells, key effector cells that release soluble pro-inflammatory mediators responsible for undesired reactions to particular allergens. We investigated aeNPs directly associating with mast cells and their influence on allergen-mediated degranulation using the mast cell activation test (MAT)3.

Materials and Methods::

Biodegradable 50:50 poly(lactide-co-glycolide) (PLG) and the surfactant poly(ethylene-alt-maleic anhydride) (PEMA) were used to make ovalbumin (OVA) or peanut (PE) aeNPs. BALB/cJ mice were sensitized to OVA antigen with intraperitoneal injections of OVA/aluminum hydroxide on days 0 and 14, treated intravenously with aeNPs or control on days 28 and 42, and intragastrically challenged with OVA antigen 7 times between days 45 and 59. On day 60, serum, mesenteric lymph nodes (mLN), and small intestine lamina propria (SILP) were harvested and were analyzed for mast cell activation and frequency. For the MAT, Laboratory of Allergic Diseases 2 (LAD2) human mast cells were sensitized overnight with 500 ng/mL human myeloma IgE. aeNPs were subsequently added to the cells 3 hours prior to activation with 5 μg/mL rabbit anti-human IgE and/or 1 μg/mL ionomycin. The cells were then prepared for flow cytometry and were stained for viability and degranulation markers CD63 and CD107a.

Results, Conclusions, and Discussions::

Results and Discussion: The OVA aeNPs associate with significantly more mast cells in the SILP of OVA sensitized mice than in PBS sensitized control mice after one dose of aeNPs. OVA aeNP treatment also significantly reduces serum mast cell protease 1 (MCPT-1) secretion, which is indicative of mast cell degranulation, in OVA sensitized mice receiving OVA aeNP treatment compared to PBS control treatment. The frequency of mast cells in the mLN and SILP decreases from PBS treated to OVA aeNP treated OVA sensitized mice. In the MAT, IgE-sensitized LAD2 mast cell survival decreases when PE aeNPs are added to anti-IgE treated or ionomycin treated cells compared to anti-IgE or ionomycin treated controls without PE aeNPs. The number of CD63+CD107a+ activated LAD2 cells decreases when PE aeNPs are added to anti-IgE treated or ionomycin treated cells compared to anti-IgE or ionomycin treated controls without PE aeNPs.

Conclusions: Our aeNPs associate directly in an antigen-specific manner with mast cells in vivo, ultimately reducing mast cell degranulation as measured by MCPT-1 as well as mast cell frequency in the gut. The MAT shows that mast cell activation and survival decreases when aeNPs are added to anti-IgE treated or ionomycin treated cells in vitro. Future studies would involve assessing the impact of IgE-mediated interactions of aeNPs and mast cells by using allergic patient sera to sensitize the LAD2 mast cells. These results shed light onto how aeNPs can modulate effector cells to reduce allergen reactivity and can inform the design of more effective food allergy therapies and diagnostics.

Acknowledgements (Optional): :

References (Optional): :

References: (1) Hughes, KR. et al. Front Allergy. 2022 Feb 7; 3:829605. (2) Smarr, CB et al. Proc Natl Acad Sci USA. 2016 May 3; 113(18):5059-64. (3) Bahri R, et al. J Allergy Clin Immunol. 2018 Aug; 142(2):485-496.e16.