Citrus Tachibana Leaf Extract Mitigates Symptoms of Food Allergy by Inhibiting Th2-Associated Responses.
Although the incidence of food allergy continues to rise, there have been no effective therapeutic strategies. Citrus fruits contain a number of bioactive flavonoids with immune-regulatory functions. The objective of this study was to determine whether Citrus tachibana (fruit body with peel, leaves, and branch) can protect against the development of food allergy and the mechanism behind it, and to identify the active compound(s) responsible. We found that C. tachibana leaf extract (CLE) mitigated ovalbumin (OVA)-induced food allergy symptoms including increased rectal temperature, diarrhea, and anaphylaxis. This mitigation was likely due to CLE-mediated decreases in cytokine release from T-helper 2 cells (Th2 cells) in mesenteric lymph nodes. Moreover, higher levels of CLE attenuated systemic Th2 cell-mediated responses in mouse splenocytes sensitized with OVA+Alum. This was evidenced by CLE-mediated reductions in Th2 cytokine release, including interleukin (IL)-4, IL-5, and IL-13, but not the Th1 cytokines IL-12 and interferon (IFN)-γ, which was attributable to decreased gene expression levels. We also identified kaempferol as the most potent compound for reducing Th2-associated responses in splenocytes. The findings of this study suggest that CLE suppresses Th2-cell-mediated immune responses, contributing to alleviation of food allergy symptoms, and that kaempferol is a flavonoid with potential antiallergenic activity that targets Th2 cell-induced responses.
Div. of Creative Food Science for Health, Korea Food Research Inst, Seongnam, 463-746, Republic of Korea.
Min-Yu
MY
Chung
Food Biotechnology Program, Korea Univ. of Science and Technology, Daejeon, 305-350, Republic of Korea.
Hee Soon
HS
Shin
Div. of Creative Food Science for Health, Korea Food Research Inst, Seongnam, 463-746, Republic of Korea.
Dae Woon
DW
Choi
Food Biotechnology Program, Korea Univ. of Science and Technology, Daejeon, 305-350, Republic of Korea.
Dong-Hwa
DH
Shon
D000534:Alum Compounds / Q000009:adverse effects; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002957:Citrus / Q000737:chemistry*; D016207:Cytokines / Q000378:metabolism; D005260:Female; D005512:Food Hypersensitivity / Q000188:drug therapy* / Q000276:immunology; D005638:Fruit / Q000737:chemistry; D044949:Kaempferols / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000009:adverse effects; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry*; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018418:Th2 Cells / Q000187:drug effects
D000534:Alum Compounds; D016207:Cytokines; D044949:Kaempferols; D010936:Plant Extracts; C446402:ovalbumin-alum; C006552:kaempferol; D010047:Ovalbumin
Citrus tachibana leaf extract; Th2; food allergy; kaempferol; ovalbumin