Supplementary Material for: Cutaneous or Respiratory Exposures to Peanut Allergens in Mice and Their Impacts on Subsequent Oral Exposure

Background: Recent data suggested that non-gastrointestinal exposure can lead to sensitisation to food allergens. We thus assessed the immune impact of respiratory or cutaneous exposure to peanut proteins on non-altered epithelium and investigated the effect of such pre-exposure on subsequent oral administration of peanut. Methods: BALB/cJ mice were exposed to purified Ara h 1 or to a non-defatted roasted peanut extract (PE) by simple deposit of allergens solutions on non-altered skin or in the nostrils. Exposures were performed 6 times at weekly intervals. Pre-exposed mice then received intra-gastric administrations of PE alone or in the presence of the Th2 mucosal adjuvant cholera toxin (CT). The specific humoral and cellular immune response was assessed throughout the protocol. Results: Both cutaneous and respiratory exposures led to the production of specific IgG1. Local and systemic IL-5 and IL-13 production were also evidenced, demonstrating activation of specific Th2 cells. This effect was dose-dependent and most efficient via the respiratory route. Moreover, these pre-exposures led to the production of specific IgE antibodies after gavage with PE, whatever the presence of CT. Conclusions: Cutaneous or respiratory exposures to peanut induce Th2 priming in mice. Moreover, pre-exposures promote further sensitisation via the oral route without the use of CT; this proposes a new adjuvant-free experimental model of sensitisation to food that may reflect a realistic exposure pattern in infants. These results also suggest that non-gastrointestinal peanut exposure should be minimised in high-risk infants, even those with non-altered skin, to potentially reduce allergic sensitisation to this major food allergen.

背景：近期研究数据表明，非胃肠道暴露可引发食物过敏原致敏。本研究旨在评估呼吸道或皮肤暴露花生蛋白对未受损上皮的免疫影响，并探究此类预暴露对后续经口摄入花生的效应。
方法：将BALB/cJ小鼠通过将过敏原溶液简单涂抹于未受损皮肤或鼻腔内的方式，暴露于纯化的Ara h 1或非脱脂烘焙花生提取物（peanut extract, PE）。暴露实验每周1次，共进行6次。预暴露后的小鼠随后接受经胃内单独给予PE，或联合Th2型黏膜佐剂霍乱毒素（cholera toxin, CT）的给药处理。本实验全程评估了特异性体液与细胞免疫应答。
结果：皮肤与呼吸道暴露均可诱导特异性IgG1产生。局部及全身的IL-5与IL-13表达均得到证实，表明特异性Th2细胞被激活。该效应呈剂量依赖性，且经呼吸道暴露时效果最为显著。此外，无论是否联合CT，此类预暴露在经PE灌胃后均可诱导特异性IgE抗体产生。
结论：皮肤或呼吸道暴露于花生可诱导小鼠的Th2细胞致敏启动。此外，无需使用CT即可通过经口途径进一步增强预暴露诱导的致敏效应；此结果构建了一种新型无佐剂食物致敏实验模型，可模拟婴儿真实的过敏原暴露模式。本研究结果同时提示，对于高风险婴儿，即便皮肤完整，也应尽量减少其非胃肠道途径的花生暴露，以降低该主要食物过敏原引发过敏致敏的潜在风险。