Enhanced Prophylactic and Therapeutic Effects of Polylysine-Modified Ara h 2 DNA Vaccine in a Mouse Model of Peanut Allergy

Abstract

Background: The prevalence of food allergy has been increasing, but treatment is very limited. DNA vaccination has been recognized as a promising method for the treatment of allergic diseases; however, poor immunogenicity has hindered its application. Methods: BALB/c mice were intradermally injected with plasmid DNA encoding the peanut protein Ara h 2 (pAra h 2) or pAra h 2 pretreated with poly-<smlcap>L</smlcap>- lysine (PLL) before or after sensitization with Ara h 2 protein. Ara h 2-specific antibodies were measured by ELISA. CD207+ dendritic cells (DCs) and Treg cells in draining lymph nodes were analyzed by flow cytometry after DNA immunization, and cytokine production in splenocytes was also analyzed. Results: In the prophylactic study, pretreatment with pAra h 2 or PLL-pAra h 2 resulted in lower levels of Ara h 2-specific IgG1, IgG2a, and IgE after sensitization with Ara h 2 protein, and mice in the PLL-pAra h 2 group had a significantly lower level of antibodies than those in the pAra h 2 group. In the treatment study, intradermal injection with pAra h 2 or PLL-pAra h 2 after Ara h 2 protein sensitization significantly decreased the level of Ara h 2-specific antibodies, and PLL- pAra h 2 had stronger effects than pAra h 2. There were increased numbers of CD207+ DCs and Treg cells in the mice receiving intradermal injection with PLL-pAra h 2, and splenocytes from PLL-pAra h 2-treated mice secreted increased levels of IFN-γ and IL-10. Conclusions: Modification of pAra h 2 with PLL improved its prophylactic and therapeutic effects in peanut-allergic mice.

Outstanding animal studies in allergy I. From asthma to food allergy and anaphylaxis

“…Plasmid DNA encoding the peanut-protein (p) Ara h 2 or pAra h 2 mixed with poly- l -lysine were injected intradermally either before or after sensitization with Ara h 2 [57]. The treatment containing poly- l -lysine was more effective in preventing specific serum antibodies and temperature drop upon challenge when applied before sensitization, inducing CD207 + DCs in draining lymph nodes of skin, CD25 + Foxp3 + Treg cells in lymph nodes and spleen, as well as IFN-γ and IL-10 in splenocytes.…”

Therapeutic DNA vaccine attenuates itching and allergic inflammation in mice with established biting midge allergy

“…However, other adjuvants were not tested. For example poly-L-lysine (PLL), which has been reported to improve the prophylactic and therapeutic effect of the peanut allergen Ara h 2 DNA vaccine in peanut-allergic mice [26]. Furthermore, whether the For t 2 DNA vaccine can last long enough to cover the whole midge season requires further investigation.…”

Applying the adverse outcome pathway (AOP) for food sensitization to support in vitro testing strategies

“…A high increased secretion of Th2 cytokines (IL-4, IL-5, IL-13) has been observed in all the studies, whereas some discrepancies were observed between allergenic proteins in their potency to induce IFN-γ (Stojadinovic et al, 2014;Vonk et al, 2017) and IL-10 (Vonk et al, 2017). A few studies have measured increased levels of IL-17 (Lozano-Ojalvo et al, 2017;Rupa, Nakamura, Katayama, & Mine, 2014), while in other limited number of studies IL-22 and TNF-α levels showed no differences compared to non-sensitized control cells (Pablos-Tanarro et al, 2016;Zhu et al, 2016).…”

“…Levels of secreted cytokines are often evaluated by ELISA or flow cytometry in cell culture supernatants. This method has been used to evaluate several food allergens from cow's milk (Kanjarawi et al, 2011;Stojadinovic et al, 2014), peanut (Smit et al, 2015;Zhu et al, 2016), hen's egg (Pablos-Tanarro, Lopez-Exposito, Lozano-Ojalvo, Lopez-Fandino, & Molina, 2016;Sun et al, 2016), soybeans (Sun et al, 2013) and shrimp (Wai et al, 2016). Moreover, extracts from whey, hen's egg white, peanut, cashew, walnut and sesame seeds have also been evaluated using this method (Lozano-Ojalvo et al, 2017;Smit et al, 2015;Vonk et al, 2017).…”