PO.IM02.02 · 免疫学
肿瘤代谢物D2HG重编程巨噬细胞以驱动IDH1突变型胆管癌中的免疫抑制
The oncometabolite D2HG reprograms macrophages to drive immunosuppression in IDH1-mutant cholangiocarcinoma
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
背景：肝内胆管癌（CCA）是一种侵袭性原发性肝癌，约20%的病例由异柠檬酸脱氢酶1（mIDH1）突变驱动。与IDH1野生型肿瘤相比，mIDH1 CCA表现出富含M2样巨噬细胞的免疫抑制微环境，且相较于一般CCA人群，其从免疫检查点治疗中获益可能较少，提示肿瘤-免疫相互作用参与了治疗耐药。mIDH1肿瘤分泌肿瘤代谢物D2HG，但其对肿瘤微环境（TME）内巨噬细胞的影响仍未被充分了解。
方法：我们将THP-1单核细胞（一种常用于模拟巨噬细胞分化的人髓系白血病细胞系）以及PBMC来源的巨噬细胞暴露于D2HG。采用流式细胞术、RT-qPCR及Luminex评估免疫抑制标志物（CD206、CD163、IL-10）的表达及细胞因子分泌（IL-10、IL-4、IL-13）。通过BODIPY染色定量脂质摄取与蓄积，并通过流式细胞术和RT-qPCR检测CD36表达。Seahorse代谢检测及脂肪酸氧化分析评估代谢活性，同时结合活细胞成像的吞噬实验评估巨噬细胞功能。
结果：暴露于与mIDH1 TME中相符的病理相关水平的D2HG，使THP-1和PBMC来源的巨噬细胞上调免疫抑制标志物（包括CD206、CD163和IL-10），同时增加IL-10、IL-4和IL-13的分泌。在功能上，与未处理细胞相比，D2HG处理的巨噬细胞吞噬能力降低了51%。机制研究显示，D2HG增强了脂质摄取并强烈上调了脂质转运体CD36。尽管脂质蓄积增加，Seahorse分析和脂肪酸氧化检测却未显示能量生成的上升，表明脂质并未被代谢利用。BODIPY染色证实了中性脂质的蓄积，支持了脂质负载型巨噬细胞表型的形成。对mIDH1肿瘤的代谢脂质组学分析显示，其脂质含量高于IDH1野生型肿瘤，提示mIDH1 CCA的TME富含脂质。这种肿瘤来源的脂质丰度，加上D2HG通过CD36诱导巨噬细胞脂质摄取的上调，很可能促进了一种协同过程，即巨噬细胞摄取过量脂质，从而强化其脂质负载型、免疫抑制性表型。
结论：肿瘤代谢物D2HG将巨噬细胞重编程为一种富含脂质、代谢改变的免疫抑制状态。该机制揭示了突变型IDH1肿瘤如何塑造免疫微环境，并凸显CD36及脂质代谢作为恢复mIDH1 CCA中抗肿瘤巨噬细胞功能的潜在治疗靶点。
查看英文原文 English abstract
Background: Intrahepatic cholangiocarcinoma (CCA) is an aggressive primary liver cancer, with ~20% of cases driven by mutations in isocitrate dehydrogenase 1 (mIDH1). Compared with IDH1 wild-type tumors, mIDH1 CCA exhibits an immunosuppressive microenvironment enriched for M2-like macrophages and may derive reduced benefit from immune checkpoint therapy than the general CCA population, suggesting tumor-immune interactions contribute to therapeutic resistance. mIDH1 tumors secrete the oncometabolite D2HG, but its effects on macrophages within the tumor microenvironment (TME) remain incompletely understood.
Methods: We exposed THP-1 monocytes, a human myeloid leukemia cell line commonly used to model macrophage differentiation, and PBMC-derived macrophages to D2HG. Flow cytometry, RT-qPCR, and Luminex were used to assess expression of immunosuppressive markers (CD206, CD163, IL-10) and cytokine secretion (IL-10, IL-4, IL-13). Lipid uptake and accumulation was quantified by BODIPY staining, and CD36 expression was measured by flow cytometry and RT-qPCR. Seahorse metabolic assays and fatty acid oxidation analyses evaluated metabolic activity, while phagocytosis assays with live-cell imaging assessed macrophage function.
Results: Exposure to pathologically relevant levels of D2HG that mirror those in the mIDH1 TME led THP-1 and PBMC-derived macrophages to upregulate immunosuppressive markers including CD206, CD163, and IL-10, while also increasing secretion of IL-10, IL-4, and IL-13. Functionally, D2HG-treated macrophages showed a 51% reduction in phagocytic capacity compared to untreated cells. Mechanistic studies revealed that D2HG enhanced lipid uptake and strongly upregulated the lipid transporter CD36. Despite increased lipid accumulation, Seahorse analyses and fatty acid oxidation assays showed no rise in energy production, indicating lipids were not metabolically utilized. BODIPY staining confirmed neutral lipid accumulation, supporting the development of a lipid-laden macrophage phenotype. Metabolic lipidomic analyses of mIDH1 tumors revealed higher lipid content than IDH1 wild-type tumors, suggesting that the mIDH1 CCA TME is enriched in lipids. This tumor-derived lipid abundance, together with D2HG-induced upregulation of lipid uptake in macrophages via CD36, likely promotes a cooperative process in which macrophages take up excess lipids, reinforcing their lipid-laden, immunosuppressive phenotype.
Conclusion: The oncometabolite D2HG reprograms macrophages into a lipid-rich, metabolically altered, immunosuppressive state. This mechanism reveals how mutant IDH1 tumors shape the immune microenvironment and highlights CD36 and lipid metabolism as potential therapeutic targets to restore antitumor macrophage function in mIDH1 CCA.
利益披露 Disclosure
S. E. Young, None..
E. Kartalia, None..
J. DeBetta, None..
J. Leatherman, None..
T. Lopez-Vidal, None..
E. Y. He, None.