School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan; Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
Department of Public Health, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan; The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China.
Phytomedicine. 2024 Dec;135:156013. doi: 10.1016/j.phymed.2024.156013. Epub 2024 Aug 30.
Allergic asthma is a chronic bronchial inflammatory disease closely associated with abnormal immune responses of dendritic cells (DCs) and allergen-specific type 2 T helper (Th2) cells. Indirubin (IR), a natural aryl hydrocarbon receptor (AhR) ligand, exerts anti-inflammatory and immunomodulatory properties.
In this study, we aimed to clarify whether IR exhibits immunomodulatory action on DCs via AhR activation and investigated the antiallergic effects of IR in a mouse model of allergic asthma.
Lipopolysaccharide (LPS)-activated bone marrow-derived DCs were treated with IR. Their mRNA expressions, cytokine production, and phenotype patterns were determined by a quantitative real-time PCR, ELISA, flow cytometry, and RNA sequencing. The mixed lymphocyte reaction was utilized to evaluate the regulatory function of IR-treated DCs on T-cell differentiation. Moreover, mice with ovalbumin (OVA)-induced allergic asthma were treated with IR. Thereafter, the airway hyperresponsiveness (AHR), allergen-specific IgE production, cytokine levels, airway inflammation, and T-cell responses were evaluated.
Treatment of LPS-stimulated DCs with 20 μM IR significantly reduced IL-12 and TNF-α production while increasing IL-10 secretion. Meanwhile, these DCs expressed decreased levels of CD80 but increased levels of Jagged 1 surface molecules. However, the effects of IR on DCs were reversed by pretreatment with the AhR antagonist, CH223191. Additionally, the coculture of these tolerogenic-like DCs with allogeneic CD4T cells promoted the generation of Foxp3 regulatory T (Treg) cells. A transcriptomic analysis identified several downregulated genes that are involved in regulating cell migration, cytokine secretion, and inflammatory responses in DCs after IR treatment. In an asthmatic murine model, oral administration of 25 mg kg body weight of IR efficiently alleviated the development of AHR, OVA-specific IgE production, and levels of Th2-type cytokines (IL-4, IL-5, and IL-13) and the CCL11 chemokine. IR treatment also attenuated inflammatory cell recruitment and mucus production in the lungs. Notably, an enhanced frequency of Foxp3 Treg cells and reduced effector T-cell proliferation associated with increased levels of IL-10 and TGF-β were observed in IR-treated mice.
IR can induce tolerogenic-like BMDCs which promote the differentiation of Treg cells. Importantly, the expansion of Foxp3 Treg cells contributed to the therapeutic efficacy of IR against allergic asthma.
过敏性哮喘是一种慢性支气管炎症性疾病，与树突状细胞（DCs）和过敏原特异性 2 型 T 辅助（Th2）细胞的异常免疫反应密切相关。靛玉红（IR）是一种天然的芳烃受体（AhR）配体，具有抗炎和免疫调节作用。
本研究旨在通过 AhR 激活阐明 IR 是否对 DC 具有免疫调节作用，并在过敏性哮喘小鼠模型中研究 IR 的抗过敏作用。
用 IR 处理脂多糖（LPS）激活的骨髓来源的 DCs。通过实时定量 PCR、ELISA、流式细胞术和 RNA 测序来确定其 mRNA 表达、细胞因子产生和表型模式。利用混合淋巴细胞反应评估 IR 处理的 DC 对 T 细胞分化的调节功能。此外，用卵清蛋白（OVA）诱导的过敏性哮喘小鼠用 IR 治疗。然后评估气道高反应性（AHR）、过敏原特异性 IgE 产生、细胞因子水平、气道炎症和 T 细胞反应。
用 20 μM IR 处理 LPS 刺激的 DCs 可显著降低 IL-12 和 TNF-α的产生，同时增加 IL-10 的分泌。同时，这些 DC 表达的 CD80 减少，但 Jagged 1 表面分子增加。然而，用 AhR 拮抗剂 CH223191 预处理可逆转 IR 对 DC 的作用。此外，这些耐受性样 DC 与同种异体 CD4T 细胞共培养可促进 Foxp3 调节性 T（Treg）细胞的生成。转录组分析表明，IR 处理后，几个参与调节 DC 细胞迁移、细胞因子分泌和炎症反应的下调基因。在哮喘小鼠模型中，口服 25mgkg 体重的 IR 可有效缓解 AHR、OVA 特异性 IgE 产生以及 Th2 型细胞因子（IL-4、IL-5 和 IL-13）和趋化因子 CCL11 的水平。IR 治疗还减轻了肺部炎症细胞募集和粘液产生。值得注意的是，在 IR 治疗的小鼠中观察到 Foxp3 Treg 细胞的频率增加，效应 T 细胞增殖减少，与 IL-10 和 TGF-β水平升高相关。
IR 可诱导耐受性样 BMDCs，促进 Treg 细胞的分化。重要的是，Foxp3 Treg 细胞的扩增有助于 IR 治疗过敏性哮喘的疗效。
