Key Lab of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, China.
National Research Center of Engineering Technology for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha, Hunan 410128, China.
Food Funct. 2023 Feb 21;14(4):2059-2073. doi: 10.1039/d2fo03404b.
Ovalbumin (OVA), a commonly consumed food protein, can cause severe allergies and intestinal immune disorders. L-Theanine (LTA) and epigallocatechin gallate (EGCG) regulate intestinal immunity. However, it is unclear whether an LTA and EGCG combined intervention can alleviate OVA allergy (OVA-A) by modulating intestinal-specific immunity, and it is unknown whether there is a synergistic effect between LTA and EGCG. Therefore, we treated BALB/c OVA-sensitized mice with LTA, EGCG, or a combination of both (LTA + EGCG) to investigate the effects of LTA and EGCG on intestinal-specific immunity regulation and underlying mechanisms. Female mice were intraperitoneally injected with OVA to establish OVA-sensitive mouse models. MLEO LTA + EGCG (20 mg kg d LTA + 80 mg kg d EGCG) and HLEO (30 mg kg d LTA + 120 mg kg d EGCG) exerted more beneficial effects on alleviating OVA-A (weight gain, allergy score, jejunum structure, mast cell [MC] degranulation, thymus and spleen indices) than LTA or EGCG alone ( < 0.01). Based on the alleviation of OVA-A by LTA + EGCG, we selected MLEO mice for 16S rDNA, flow cytometry, and western blot analyses. The 16S rDNA results showed that MLEO increased the abundance of , , and , and decreased that of ( < 0.01). The flow cytometry and western blotting results indicated that MLEO reduced the number of dendritic cells available to capture OVA, thereby lowering the Th2 immune response and decreasing the IL-4 and IL-13 levels. Meanwhile, the attenuation of the Th2 immune response inhibits the cross-linking of OVA and FcεRI, thus reducing MC degranulation and decreasing the serum HIS and mMCPT-1 levels through the FcεRI/Btk/PLCγ signaling pathway. LTA + EGCG also inhibits the Th2 immune response through the FcεRI/Lyn/Syk/PI3K/AKT signaling pathway and decreases the serum IL-4 and IL-13 levels. Notably, LTA + EGCG promotes the Treg and Th1 immune responses and inhibits the Th17 immune response, altering the levels of the corresponding cytokines. Therefore, LTA + EGCG can synergistically alleviate OVA-A by regulating intestinal immunity through MC degranulation inhibition.
卵清蛋白（OVA）是一种常见的食用蛋白，可引起严重过敏和肠道免疫紊乱。L-茶氨酸（LTA）和表没食子儿茶素没食子酸酯（EGCG）可调节肠道免疫。然而，尚不清楚 LTA 和 EGCG 的联合干预是否可以通过调节肠道特异性免疫来缓解卵清蛋白过敏（OVA-A），也不清楚 LTA 和 EGCG 之间是否存在协同作用。因此，我们用 LTA、EGCG 或两者的组合（LTA+EGCG）治疗 BALB/c 卵清蛋白致敏小鼠，以研究 LTA 和 EGCG 对肠道特异性免疫调节的影响及其潜在机制。雌性小鼠经腹腔注射卵清蛋白建立卵清蛋白敏感小鼠模型。MLEO LTA+EGCG（20 mg/kg/d LTA+80 mg/kg/d EGCG）和 HLEO（30 mg/kg/d LTA+120 mg/kg/d EGCG）对缓解 OVA-A（体重增加、过敏评分、空肠结构、肥大细胞[MC]脱颗粒、胸腺和脾脏指数）的作用优于 LTA 或 EGCG 单独使用（<0.01）。基于 LTA+EGCG 对 OVA-A 的缓解作用，我们选择 MLEO 小鼠进行 16S rDNA、流式细胞术和 Western blot 分析。16S rDNA 结果表明，MLEO 增加了、、和的丰度，降低了的丰度（<0.01）。流式细胞术和 Western blot 结果表明，MLEO 减少了可捕获卵清蛋白的树突状细胞的数量，从而降低了 Th2 免疫反应并降低了 IL-4 和 IL-13 水平。同时，Th2 免疫反应的衰减抑制了卵清蛋白与 FcεRI 的交联，从而通过 FcεRI/Btk/PLCγ 信号通路降低 MC 脱颗粒和血清 HIS 和 mMCPT-1 水平。LTA+EGCG 还通过 FcεRI/Lyn/Syk/PI3K/AKT 信号通路抑制 Th2 免疫反应并降低血清 IL-4 和 IL-13 水平。值得注意的是，LTA+EGCG 通过抑制 MC 脱颗粒来调节肠道免疫，从而促进 Treg 和 Th1 免疫反应并抑制 Th17 免疫反应，改变相应细胞因子的水平。因此，LTA+EGCG 可以通过抑制肥大细胞脱颗粒来协同缓解 OVA-A。
