Department of Pharmacology of Chinese Materia Medica, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 210009, China.
Acta Pharmacol Sin. 2022 Apr;43(4):963-976. doi: 10.1038/s41401-021-00717-1. Epub 2021 Jul 15.
Bergenin is a natural PPARγ agonist that can prevent neutrophil aggregation, and often be used in clinics for treating respiratory diseases. Recent data show that Th17 cells are important for neutrophil aggregation and asthma through secreting IL-17A. In this study, we investigated the effects of bergenin on Th17 differentiation in vitro and subsequent neutrophilic asthma in mice. Naïve T cells isolated from mouse mesenteric lymph nodes were treated with IL-23, TGF-β, and IL-6 to induce Th17 differentiation. We showed that in naïve T cells under Th17-polarizing condition, the addition of bergenin (3, 10, 30 μM) concentration-dependently decreased the percentage of CD4 IL-17A T cells and mRNA expression of specific transcription factor RORγt, and function-related factors IL-17A/F, IL-21, and IL-22, but did not affect the cell vitality and apoptosis. Furthermore, bergenin treatment prevented GLS1-dependent glutaminolysis in the progress of Th17 differentiation, slightly affected the levels of SLC1A5, SLC38A1, GLUD1, GOT1, and GPT2. Glutamine deprivation, the addition of glutamate (1 mM), α-ketoglutarate (1 mM), or GLS1 plasmid all significantly attenuated the above-mentioned actions of bergenin. Besides, we demonstrated that bergenin (3, 10, and 30 μM) concentration-dependently activated PPARγ in naïve T cells, whereas PPARγ antagonist GW9662 and siPPARγ abolished bergenin-caused inhibition on glutaminolysis and Th17 differentiation. Furthermore, we revealed that bergenin inhibited glutaminolysis by regulating the level of CDK1, phosphorylation and degradation of Cdh1, and APC/C-Cdh1-mediated ubiquitin-proteasomal degradation of GLS1 after activating PPARγ. We demonstrated a correlation existing among bergenin-affected GLS1-dependent glutaminolysis, PPARγ, "CDK1-APC/C-Cdh1" signaling, and Th17 differentiation. Finally, the therapeutic effect and mechanisms for bergenin-inhibited Th17 responses and neutrophilic asthma were confirmed in a mouse model of neutrophilic asthma by administration of GW9662 or GLS1 overexpression plasmid in vivo. In conclusion, bergenin repressed Th17 differentiation and then alleviated neutrophilic asthma in mice by inhibiting GLS1-dependent glutaminolysis via regulating the "CDK1-APC/C-Cdh1" signaling after activating PPARγ.
没食子酰基 Bergenin 是一种天然的过氧化物酶体增殖物激活受体 γ（PPARγ）激动剂，可预防中性粒细胞聚集，常用于临床治疗呼吸系统疾病。最近的数据表明，Th17 细胞通过分泌白介素 17A（IL-17A）在中性粒细胞聚集和哮喘中起重要作用。本研究旨在探讨 Bergenin 在体外对 Th17 分化的影响及其在小鼠中性粒细胞性哮喘中的后续作用。从小鼠肠系膜淋巴结中分离出初始 T 细胞，用白细胞介素 23（IL-23）、转化生长因子-β（TGF-β）和白细胞介素 6（IL-6）诱导 Th17 分化。结果表明，在 Th17 极化条件下的初始 T 细胞中，Bergenin（3、10、30 μM）浓度依赖性地降低 CD4+IL-17A T 细胞的比例和特定转录因子 RORγt 的 mRNA 表达，以及功能相关因子 IL-17A/F、IL-21 和 IL-22，但不影响细胞活力和凋亡。此外，Bergenin 治疗可预防 Th17 分化过程中谷氨酰胺分解代谢依赖于 GLS1 的作用，对 SLC1A5、SLC38A1、GLUD1、GOT1 和 GPT2 的水平影响较小。谷氨酰胺剥夺、添加谷氨酸（1mM）、α-酮戊二酸（1mM）或 GLS1 质粒均显著减弱了 Bergenin 的上述作用。此外，我们证明 Bergenin（3、10 和 30 μM）浓度依赖性地激活初始 T 细胞中的过氧化物酶体增殖物激活受体 γ（PPARγ），而过氧化物酶体增殖物激活受体 γ（PPARγ）拮抗剂 GW9662 和 siPPARγ 则消除了 Bergenin 引起的谷氨酰胺分解代谢和 Th17 分化的抑制作用。此外，我们揭示了 Bergenin 通过调节 CDK1 的水平、Cdh1 的磷酸化和降解以及 APC/C-Cdh1 介导的 GLS1 泛素蛋白酶体降解，在激活过氧化物酶体增殖物激活受体 γ（PPARγ）后抑制 GLS1 依赖性谷氨酰胺分解代谢。我们证明了 Bergenin 影响的 GLS1 依赖性谷氨酰胺分解代谢、过氧化物酶体增殖物激活受体 γ（PPARγ）、“CDK1-APC/C-Cdh1”信号与 Th17 分化之间存在相关性。最后，通过体内给予 GW9662 或 GLS1 过表达质粒，在中性粒细胞性哮喘小鼠模型中证实了 Bergenin 抑制 Th17 反应和中性粒细胞性哮喘的治疗效果和机制。总之，Bergenin 通过激活过氧化物酶体增殖物激活受体 γ（PPARγ）后调节“CDK1-APC/C-Cdh1”信号，抑制 GLS1 依赖性谷氨酰胺分解代谢，从而抑制 Th17 分化，进而减轻小鼠中性粒细胞性哮喘。
