Delivery of Peanut Allergen Powder Into Epidermis For Safe Immunotherapy

Project Summary / AbstractThe objective of this proposal is to develop an effective and safe epicutaneous immunotherapy (EPIT) forpeanut allergy. Among various allergen-specific immunotherapies, EPIT is the safest but least effectivetherapy. It is extremely challenging to deliver allergens into the epidermis via intact skin, despite that thenon-vascularized tissue imposes little anaphylactic risk. To enhance epidermic delivery of allergens withoutprovoking any significant skin irritation, we used ablative fractional laser to generate an array of self-renewable microchannels in the epidermis, onto which an antigen powder-based microarray patch wasapplied resulting in ~80% delivery efficiency in ~1 hr via both human and pig skins, concurrent with little skinirritation. We also identified that a combination of CpG and 1,25-dihydroxyvitamin D3 (VD3) could robustlyaugment TGF-β and IL-10 production at the site of allergen delivery and vigorously enhance T regulatory(Treg) cell responses systemically. Only 3 doses of EPIT over two weeks sufficiently inhibited allergen-specific IgE responses in mice, which was unattainable by 8 times of conventional subcutaneousimmunotherapy (SCIT) over three weeks. To further tailor this technology for clinical uses, we propose todeliver powdered allergens directly by Powder-Laden, Dissolvable MicroNeedle Arrays (PLD-MNAs), whichno longer needs laser to perforate the skin. The MNA will be made of highly biocompatible and dissolvablehyaluronic acid (HA) with a cave in the basal portion of each MN. The cave will be about 25~30 µm in depth,similar to the depth of mouse epidermis and can be filled with allergen powder directly. The MNA will bedissolved in 15~20 min after skin insertion, exposing the powder in the epidermis that continuously andactively attracts antigen presenting cells (APCs). We will fabricate PLD-MNAs by loading a mixture of CpG,VD3, and peanut allergens (PNA) into caved MNAs. The resultant PLD-MNAs will be applied into the skin ofsensitized C3H/HeJ mice, followed by evaluation of delivery efficiency, skin irritation, innate immunity, anyPNA leakage into blood as well as humoral and Th1/Treg cell responses against PNA. Skin irritation and anytrace amount of PNA leaking into blood will be also assessed in sensitized newborn pigs to confirm safety ofthe therapy. Aim 2 will seek in a murine peanut allergy model whether 3 doses of the PLD-MNAs are superiorto conventional 8 doses of conventional SCIT in treatment of peanut allergy. The PLD-MNA, if successful,would confer safer and faster treatments of peanut allergy and can be readily extended to other IgE-mediatedallergies.