Department of Immunology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, 11108 Belgrade, Serbia.
Section of Organic Chemistry & Biochemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
Molecules. 2024 Jun 23;29(13):2988. doi: 10.3390/molecules29132988.
Aryl Hydrocarbon Receptor (AHR) ligands, upon binding, induce distinct gene expression profiles orchestrated by the AHR, leading to a spectrum of pro- or anti-inflammatory effects. In this study, we designed, synthesized and evaluated three indole-containing potential AHR ligands (FluoAHRL: AGT-4, AGT-5 and AGT-6). All synthesized compounds were shown to emit fluorescence in the near-infrared. Their AHR agonist activity was first predicted using in silico docking studies, and then confirmed using AHR luciferase reporter cell lines. FluoAHRLs were tested in vitro using mouse peritoneal macrophages and T lymphocytes to assess their immunomodulatory properties. We then focused on AGT-5, as it illustrated the predominant anti-inflammatory effects. Notably, AGT-5 demonstrated the ability to foster anti-inflammatory regulatory T cells (Treg) while suppressing pro-inflammatory T helper (Th)17 cells in vitro. AGT-5 actively induced Treg differentiation from naïve CD4 cells, and promoted Treg proliferation, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) expression and interleukin-10 (IL-10) production. The increase in IL-10 correlated with an upregulation of Signal Transducer and Activator of Transcription 3 (STAT3) expression. Importantly, the Treg-inducing effect of AGT-5 was also observed in human tonsil cells in vitro. AGT-5 showed no toxicity when applied to zebrafish embryos and was therefore considered safe for animal studies. Following oral administration to C57BL/6 mice, AGT-5 significantly upregulated Treg while downregulating pro-inflammatory Th1 cells in the mesenteric lymph nodes. Due to its fluorescent properties, AGT-5 could be visualized both in vitro (during uptake by macrophages) and ex vivo (within the lamina propria of the small intestine). These findings make AGT-5 a promising candidate for further exploration in the treatment of inflammatory and autoimmune diseases.
芳香烃受体 (AHR) 配体与受体结合后，会诱导 AHR 介导的特定基因表达谱，从而产生一系列促炎或抗炎效应。在本研究中，我们设计、合成并评估了三种含吲哚的潜在 AHR 配体（FluoAHRL：AGT-4、AGT-5 和 AGT-6）。所有合成的化合物在近红外区均显示出荧光。我们首先通过计算机对接研究预测了它们的 AHR 激动剂活性，然后通过 AHR 荧光素酶报告细胞系进行了验证。我们使用小鼠腹腔巨噬细胞和 T 淋巴细胞在体外测试了 FluoAHRLs，以评估它们的免疫调节特性。然后，我们重点研究了 AGT-5，因为它显示出主要的抗炎作用。值得注意的是，AGT-5 能够在体外促进抗炎调节性 T 细胞（Treg）的分化，同时抑制促炎辅助性 T 细胞（Th）17 细胞。AGT-5 能够从幼稚 CD4 细胞中主动诱导 Treg 分化，并促进 Treg 的增殖、细胞毒性 T 淋巴细胞相关抗原 4（CTLA-4）的表达和白细胞介素 10（IL-10）的产生。IL-10 的增加与信号转导和转录激活因子 3（STAT3）表达的上调相关。重要的是，AGT-5 在体外人扁桃体细胞中也观察到了 Treg 的诱导作用。AGT-5 应用于斑马鱼胚胎时没有毒性，因此被认为在动物研究中是安全的。在口服给予 C57BL/6 小鼠后，AGT-5 可显著上调肠系膜淋巴结中的 Treg，同时下调促炎 Th1 细胞。由于其荧光特性，AGT-5 可以在体外（通过巨噬细胞摄取）和离体（在小肠固有层内）进行可视化。这些发现使 AGT-5 成为治疗炎症和自身免疫性疾病的有前途的候选药物。
