Ando Takashi, Hatsushika Kyosuke, Wako Masanori, Ohba Tetsuro, Koyama Kensuke, Ohnuma Yuko, Katoh Ryohei, Ogawa Hideoki, Okumura Ko, Luo Jian, Wyss-Coray Tony, Nakao Atsuhito
Department of Immunology, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.
J Allergy Clin Immunol. 2007 Oct;120(4):916-23. doi: 10.1016/j.jaci.2007.05.023. Epub 2007 Jul 2.
Epidemiologic studies suggest that TGF-beta in breast milk provides protection against allergic disease during infancy. However, it is unclear whether orally administered TGF-beta, such as TGF-beta in human milk, retains and exerts its activity in the intestinal mucosa and can affect immune response (tolerance) to dietary antigens.
We sought to determine whether orally administered TGF-beta is biologically active in intestinal mucosa and affects oral tolerance.
Activity of orally administered TGF-beta in the intestinal mucosa was evaluated by means of in vivo imaging with transgenic mice expressing a Smad-responsive reporter construct (SBE-luc mice), by means of immunohistochemical staining with anti-phosphorylated Smad2 antibody, and by means of real-time RT-PCR analysis of TGF-beta and Smad7 mRNA expression. The effects of orally administered TGF-beta on oral tolerance induction were assessed in mice tolerized by means of high-dose ovalbumin (OVA) feeding.
The oral administration of TGF-beta increased Smad-responsive reporter activity in the intestines of SBE-luc mice and induced Smad2 phosphorylation and TGF-beta and Smad7 mRNA expression in the intestines of BALB/c mice. Serum TGF-beta levels were also increased after oral administration of TGF-beta. BALB/c mice treated orally with OVA and TGF-beta showed augmented reduction of OVA-specific IgE and IgG1 antibodies, T-cell reactivity, and immediate-type skin reactions when compared with the mice treated orally with OVA alone.
Orally administered TGF-beta retains sufficient biologic activity in intestinal mucosa and enhances oral tolerance.
Oral administration of TGF-beta might become a potential strategy to prevent allergic diseases, such as food allergy.
流行病学研究表明，母乳中的转化生长因子-β（TGF-β）可在婴儿期预防过敏性疾病。然而，尚不清楚口服给予的TGF-β，如人乳中的TGF-β，是否能在肠黏膜中保留并发挥其活性，以及是否会影响对饮食抗原的免疫反应（耐受性）。
我们试图确定口服给予的TGF-β在肠黏膜中是否具有生物活性并影响口服耐受性。
通过对表达Smad反应性报告基因构建体的转基因小鼠（SBE-luc小鼠）进行体内成像、用抗磷酸化Smad2抗体进行免疫组织化学染色以及对TGF-β和Smad7 mRNA表达进行实时RT-PCR分析，评估口服给予的TGF-β在肠黏膜中的活性。通过高剂量卵清蛋白（OVA）喂养使小鼠产生耐受，评估口服给予的TGF-β对口服耐受性诱导的影响。
口服给予TGF-β可增加SBE-luc小鼠肠道中的Smad反应性报告基因活性，并诱导BALB/c小鼠肠道中Smad2磷酸化以及TGF-β和Smad7 mRNA表达。口服给予TGF-β后血清TGF-β水平也升高。与仅口服OVA的小鼠相比，口服OVA和TGF-β的BALB/c小鼠显示OVA特异性IgE和IgG1抗体、T细胞反应性以及速发型皮肤反应的降低更为明显。
口服给予的TGF-β在肠黏膜中保留了足够的生物活性并增强了口服耐受性。
口服给予TGF-β可能成为预防过敏性疾病（如食物过敏）的潜在策略。
