Peanut allergy is a public health concern which affects a significant proportion of the population. Accidental exposure to peanut can cause severe and fatal reactions in peanut allergic individuals and currently their only safeguard is to practise careful avoidance. Identification and protection of at-risk members of the allergic population is critical in managing this life-threatening condition. This thesis produces key data to enable this. A prospective study was performed on 60 peanut allergic participants to determine thresholds of reactivity to peanut using oral challenges with incrementally increasing amounts of peanut protein. Following a double-blind placebo-controlled peanut challenge, participants received three further peanut challenges, two with co-factors: sleep deprivation and exercise, and one without. Severity was measured using a numerical scale derived from symptoms and serum tryptase was measured at each challenge. A total of 187 challenges were performed. Findings were that the median amount of peanut protein which induces a reaction in 10% of the population (ED10) was 12.3mg (95% CI 7.3,20.4) equivalently this suggests that 90% of the allergic population will not react to doses below this level. Both sleep deprivation and exercise have a significant effect on lowering reaction threshold (ED10), by 5 times and 2.5 times respectively. Separately there is a reduction in threshold with successive challenges. Co-factors also significantly increased symptom severity during challenge reactions. In particular sleep deprivation significantly increased the severity of gastrointestinal symptoms suggesting that a stressful stimulus may affect intestinal permeability. Evidence was provided for the importance of asthma as a risk factor which increased the severity of respiratory symptoms during reaction. Using a novel visual analogue scale for measuring the participant’s perception of severity, a poor correlation was observed between the participant’s perception of the reaction and the overall numerical severity score, suggesting that participants misperceive severe symptoms. This thesis provides the first data showing that symptom patterns in repeated challenges show a high degree of homogeneity within individuals, but importantly that this symptom homogeneity is also observed across individuals. Lastly the utility of serum tryptase in identifying food allergic reactions has been disputed previously. This thesis provides evidence of its value and identifies a rise cut-off of 30% as being diagnostic of a food allergic reaction, but cautions that acute levels must be compared with baseline as this rise may occur within the normal range.

<p>The prevalence of allergic disease such as peanut (PN) allergy has increased within the last century. Environmental factors have been associated with an increased risk of developing allergic diseases. The severity of allergic diseases has also increased and clinical trials are investigating allergen-specific immunotherapy as a method to treat allergies. The purpose of this work was to identify a vaccine adjuvant that induced potent antigen-specific Th1 immune responses and determine its ability to reduce the development and severity of Th2- mediated allergic disease, using models of peanut hypersensitivity.</p><p>Three studies were performed. The first study compared a variety of vaccine adjuvants to identify a potent adjuvant with strong Th1-associated activity. This study verified that the Toll-like receptor (TLR) ligand CpG could induce potent Th1-associated immune responses. The second study tested the ability of environmental endotoxin levels and alum-adjuvanted vaccines to modulate the development of allergic disease using a mouse model of peanut allergy. Additionally, the TLR ligands, CpG and MPL, were combined with alum-adjuvanted vaccines to determine their ability to further impact allergic disease development. Results suggested that the addition of CpG to an alum-adjuvanted vaccine indirectly modified host immunity in a manner that decreased the development of PN-induced allergic disease. The last study evaluated the ability of CpG to reduce the severity of peanut allergy symptoms when combined with peanut in an immunotherapy formulation administered to peanut-hypersensitive mice. Nasal immunotherapy with PN + CpG but not PN alone or CpG alone reduced the severity of PN-induced anaphylaxis in hypersensitive mice. PN-hypersensitive mice treated with PN + CpG displayed an increased PN-specific IgG2c and IFN-γ responses. A reduction in allergic disease severity in PN-hypersensitive mice correlated with an increase in PN-specific IgG2c, IFN-γ and IL-10 responses and a reduction in PN-specific IL-13 responses, suggesting a shift from Th2 responses towards Th1 and/or T regulatory cell responses.</p><p>Taken together, the data obtained from these studies demonstrate the potent activity of CpG to induce antigen-specific Th1-associated immune responses and also reduce the severity of peanut-hypersensitivity in mice through direct and indirect association with peanut allergens.</p> / Dissertation

Background: Despite the clinical severity and rising prevalence of peanut allergy, there is a marked absence of widespread, practical treatments available for peanut-allergic patients. Peptide immunotherapy, a disease-modifying treatment that uses short peptides recognized by T cells, has been shown to reduce allergic symptoms of allergic rhinoconjunctivitis. This project investigated the ability of peptides from the major peanut allergen Ara h 1 to protect against peanut-induced anaphylaxis and induce immunomodulatory changes in a mouse model. Methods: Mice transgenic for the human leukocyte antigen DRB1*0401 were sensitized to peanut epicutaneously and treated with two intraperitoneal injections of peptides from Ara h 1. Mice were then challenged with intraperitoneal whole peanut and observed for signs of anaphylaxis. Flow cytometry was used to isolate peanut-specific CD4+ T cells labelled with Ara h 1 peptide-loaded tetramers and additional Th1, Th2, and regulatory markers. Results: Peptide-treated mice were protected from severe peanut-induced anaphylaxis. Control mice treated with a sham peptide experienced a mean maximum temperature drop of 3.2°C, while mice treated with Ara h 1 peptides experienced a drop of 1.6°C (p=0.067 vs control). Maximum clinical score was 2.5 in control mice, and 1.4 in treated mice (p=0.0097). Mean hematocrit for control mice was 52.5%, and 47% for treated mice (p=0.013). PD-1+CD4+ T cells were significantly increased in the mesenteric lymph nodes (p = 2.28e-0.05) and spleens (p = 0.014) of peptide-treated mice. MIP1-a+CD4+ T cells were significantly decreased in the peritoneal lavage (p = 0.008). Conclusion: Ara h 1 peptide immunotherapy protected against severe peanut-induced anaphylaxis in a mouse model. Peptide-treated mice experienced significantly reduced drops in core body temperature, clinical signs of allergic reaction, and hemoconcentration. Clinical protection was associated with decreased expression of the pro-inflammatory chemokine macrophage 1-a and increased expression of the surface marker programmed cell death protein 1. / Thesis / Doctor of Philosophy (PhD) / Peanut allergy is a growing public health concern. Its prevalence has doubled in the past 10 years and currently stands at 2%. Reactions to peanut account for the majority of food-induced fatal allergic reactions, termed anaphylaxis. Currently, there are no treatments available for patients with peanut allergy. Healthcare workers can only offer peanut-allergic patients advice on peanut avoidance and rescue medications in case of accidental ingestion. This research project investigated the ability of a new treatment called peptide immunotherapy to prevent severe allergic reactions to peanut in a mouse model of peanut allergy. Peptide treatment uses small portions of the peanut allergen to shift the immune response from pro-inflammatory to anti-inflammatory. After peptide treatment, peanut-allergic mice were protected from severe allergic reactions in response to peanut and their immune cells produced lower levels of pro- inflammatory molecules.

<p>While drug-loaded biodegradable polymer microparticles have found many therapeutic applications, bulk manufacturing methods produce heterogeneous populations of particles. A more highly controlled manufacturing method may provide the ability improve the microparticle characteristics such as the drug release profile. Microfluidic droplet-makers manipulate liquids on the scale of tens of microns and can produce highly regular and controlled emulsions. However, microfluidic droplet manufacturing is not typically designed for clinical translation and the chemicals used are often not biocompatible.</p><p>I developed a two-chip PDMS-based microfluidic device that can manufacture PLGA microparticle loaded with hydrophilic or hydrophobic drugs. I characterized protein-loaded microparticles made using this device and compared them with bulk-generated microparticles. The microfluidics-generated microparticles had similar release curves and encapsulation efficiencies as bulk-generated microparticles but a much narrower size distribution. I generated peanut protein-loaded microparticles with this device and tested them in a mouse model of peanut allergy, improving the particles as the project evolved to have a higher loading level and lower burst release. The microparticles improved the safety and efficacy of an immunotherapy protocol. I also encapsulated hydrophilic and hydrophobic chemotherapeutic drugs for a brain cancer model.</p> / Dissertation

<p>BACKGROUND: The ontogeny of peanut allergy (PA) is poorly understood, and the treatment of its most severe manifestation, peanut-induced anaphylaxis (PIA), remains limited to rescue epinephrine. We argued that an untargeted metabolomic analysis would be a useful hypothesis-generating tool to identify novel biomarkers, mediators and possibly therapeutic targets in PA and PIA.</p> <p>METHODS: Models of PA and PIA used in this thesis involved either the oral administration of peanut along with cholera toxin or the topical application of peanut on tape-stripped skin. Liquid-chromatography mass-spectrometry (LC-MS) was performed to identify chemical changes in the serum of mice undergoing sensitization and anaphylaxis. Flow cytometry as well as <em>in vivo</em> gain-of-function and loss-of-function immunological studies were used to determine the biological significance of particular molecules in sensitization.</p> <p>RESULTS: LC-MS followed by multivariant analysis showed that the purine metabolism pathway was altered with elevated levels of uric acid (UA) in sensitized mice. UA depletion using allopurinol and uricase fully prevented the development of the allergic and anaphylactic phenotype. Conversely, administration of UA crystals, instead of cholera toxin or tape stripping along with peanut induced a typical allergic and anaphylactic phenotype. The effects of UA and UA crystals are likely a consequence of effects on the activation of resident dendritic cells. Post-challenge metabolic analysis also revealed a distinct metabolic signature in sensitized mice, highlighted by an increase in several metabolites such as histamine. Likewise, peanut allergic patients display a distinct metabolic profile after oral peanut challenge.</p> <p>CONCLUSION: We identified UA, released after damage to the mucosa and/or skin, as a critical alarmin that facilitates the development of Th2 immunity, specifically PA and PIA. Metabolomics analyses of either mice undergoing anaphylaxis or peanut allergic children subjected to a peanut oral challenge provided an extensive overview of metabolomic changes underlying these conditions. Further studies may lead to the identification of novel biomarkers and mediators.</p> / Master of Science in Medical Sciences (MSMS)

Abstract There are eight foods that contribute to food allergies in the western world and peanut is the most common. Currently, there are no medical treatments that can cure an individual of food allergy, so avoidance of the allergic food is the only option. In the United States, there are three immunodominant allergic proteins accountable for patient sensitization to peanut, Arachis hypogea 1, 2, and 3 (Ara h 1, Ara h 2, Ara h 3). Therefore, research into why peanuts are more allergic than other foods that have homologous proteins is critical and may be obtained by studying the structural and allergenic properties of individual allergens and the changes that occur due to food processing. In this study, the basic and acidic subunits of Ara h 3 were cloned, expressed, and purified, and compared with each other and with the native Ara h 3 purified from peanut for differences in binding to IgE from peanut allergic individuals. Also, an in vitro Maillard reaction was performed on purified native raw Ara h 3 and patient serum IgE western blots were performed. This study concluded that an in vitro Maillard reaction enhanced IgE binding to Ara h 3, IgE binding to native Ara h 3 was in most cases higher than to the recombinant Ara h 3 subunits, and recognition of the acidic subunit was much higher than the and basic subunits in both the recombinant and native forms of the protein were investigated. Keywords: