Kopper Randall A, West Charles M, Helm Ricki M
Department of Chemistry, Hendrix College, Conway, Ark., USA.
Int Arch Allergy Immunol. 2006;141(3):217-22. doi: 10.1159/000095291. Epub 2006 Aug 22.
In previous studies, the major peanut allergen Ara h 1 was digested in vitro using pepsin and porcine gastric fluid. The results suggested that in vivo gastric digestion of allergen protein can be modeled accurately by peptic hydrolysis in vitro. In the current investigation, studies were designed to follow the gastrointestinal (GI) digestion of peanut allergens under true physiological conditions. In vitro digestion with porcine gastric fluid was compared with actual physiological digestion of peanut allergens in the porcine digestive tract in vivo.
Analysis of physiologic digestion was performed in piglets administered a 20-gram bolus of peanut meal followed by periodic sampling and analysis of GI contents. The pH was monitored, and digesta were analyzed by SDS-PAGE and immunoblot analysis.
Peanut meal initially neutralized stomach contents to a pH of approximately 7, which was subsequently acidified by HCl secretion within 30 min. Acidification to pH 2-4 resulted in active pepsin digestion of soluble protein in the stomach. Soluble intact protein/allergens were rapidly degraded to pepsin-resistant peptides in the stomach followed by hydrolysis of these fragments in the small intestine. Particulate material was evident in both the stomach and small intestine that could contribute to continued release of peanut allergens Ara h 1, 2 and 3.
Porcine gastric digestion of peanut proteins resembles true physiological digestion only under optimal physiologic conditions. Soluble proteins are rapidly digested and insoluble material continues to release IgE-reactive proteins throughout the GI tract. GI digestion of food allergens can play a prominent role when assessing allergens within the context of a food matrix or meal and during the sensitization phase of IgE-mediated allergy.
在先前的研究中，主要花生过敏原Ara h 1在体外使用胃蛋白酶和猪胃液进行消化。结果表明，体外胃蛋白酶水解可准确模拟过敏原蛋白在体内的胃消化过程。在当前的研究中，设计了相关实验来追踪花生过敏原在真实生理条件下的胃肠道（GI）消化情况。将猪胃液体外消化与花生过敏原在猪消化道内的实际生理消化进行了比较。
对给予20克花生粉团的仔猪进行生理消化分析，随后定期采集样本并分析胃肠道内容物。监测pH值，通过SDS - PAGE和免疫印迹分析对消化物进行分析。
花生粉最初将胃内容物中和至pH约为7，随后在30分钟内被盐酸分泌酸化。酸化至pH 2 - 4导致胃中可溶性蛋白的活性胃蛋白酶消化。可溶性完整蛋白/过敏原在胃中迅速降解为胃蛋白酶抗性肽段，并随后在小肠中被这些片段水解。胃和小肠中均可见颗粒物质，这可能导致花生过敏原Ara h 1、2和3的持续释放。
仅在最佳生理条件下，猪胃对花生蛋白的消化才类似于真实的生理消化。可溶性蛋白迅速被消化，不溶性物质在整个胃肠道中持续释放IgE反应性蛋白。在评估食物基质或餐食中的过敏原以及IgE介导的过敏致敏阶段时，食物过敏原胃肠道消化可能起重要作用。
