A novel anti-allergic property by food factor possessing high affinity lectin-like protein against IgE

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K19741
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 59:Sports sciences, physical education, health sciences, and related fields
• Research Institution: Kobe University
• Principal Investigator: Mizuno Masashi 神戸大学, 農学研究科, 教授 (00212233)
• Project Period (FY): 2018-06-29 – 2023-03-31
• Keywords: Ⅰ型アレルギー / 腸上皮細胞 / ガレクチン９ / フコイダン / コンブ

Outline of Final Research Achievements

To clarify the mechanism of Galectin 9 (Gal9) production by fucoidan administration, a culture system consisting of HT-29/RBL-2H3 cells was first constructed. It was demonstrated that the amount of Gal9 secreted to the basolateral side was increased with dose-dependent manner, and the amount of Gal9 secreted and Gal9 mRNA expression increased over time depending on the amount of fucoidan added. Furthermore, degranulation of RBL-2H3 cells was also suppressed. Next, to clarify the involvement of TLR9 as the fucoidan receptor, we evaluated its effect on Gal9 release using a TLR9 knockdown strain of HT-29 cells transfected with a TLR9 siRNA sequence. As a result, a decrease in the amount of Gal9 secreted to the basolateral side was observed upon TLR9 knockdown. In conclusion, we demonstrated that oral fucoidan suppresses type I allergy by producing Gal9 in the blood via TLR9 receptors expressed on intestinal epithelial cells.

Free Research Field

食品機能学

Academic Significance and Societal Importance of the Research Achievements

フコイダン経口摂取により、TLR9を介してIgE高親和性のガレクチン9が血中に分泌されるので、例えば既に花粉症などのアレルギー疾患を罹患した後でもその発症を抑制できることを示唆しており、これまでの抗アレルギー抑制機構とは全く異なった新規抑制機構を提唱できる。すなわち、これまでアレルギーを抑制する目的で着目されて来たTh1/Th2バランスの崩れを改善することを目的としていないため、細胞性あるいは体液性免疫への影響することなくアレルギーを改善できる可能性がある。