PO.IM01.02 · 免疫学
靶向TGR5的治疗消除胆管癌中胆汁酸驱动的髓系细胞免疫抑制
Therapeutic targeting of TGR5 abrogates bile acid driven myeloid cell immunosuppression in cholangiocarcinoma
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
背景：胆管癌（CCA）是一种治疗选择有限的侵袭性肝胆恶性肿瘤。CCA表现出独特的促结缔组织增生性和耐受性肿瘤免疫微环境（TIME），其特征是由梗阻性胆汁淤积和胆汁酸代谢失调导致的胆汁酸浓度升高。TGR5是胆汁酸信号传导的一个必需组分。我们假设，胆汁酸通过TGR5信号传导建立免疫抑制性TIME，从而促进CCA进展，而这可使用SBI-364（一种新型强效小分子TGR5抑制剂）进行治疗性靶向。
方法：对来自人肝内（iCCA）和肝门周围（pCCA）CCA肿瘤的免疫细胞进行单细胞RNA测序（scRNA-seq）。使用iCCA同基因小鼠模型（PMID: 38458319）、一种新型pCCA同基因模型以及患者来源异种移植（PDX）模型开展治疗研究。与Sanford Burnham Prebys合作，在体内评估了SBI-364这一同类首创的竞争性TGR5拮抗剂。此外，我们用经胆汁酸+/- SBI-364处理的小鼠骨髓来源单核细胞型髓系来源抑制细胞（M-MDSCs）与CD8+ T细胞开展共培养实验，以评估其功能性免疫抑制效应。
结果：人scRNA-seq显示，CCA TIME内TGR5（GPBAR1）表达显著增加，主要见于髓系细胞群体。SBI-364治疗在同基因原位iCCA模型以及重现肝门周围CCA解剖特征的新型pCCA模型中均显著降低了肿瘤负荷。相反，在荷PDX535（预测敏感）和PDX136（预测耐药）的NOD/SCID小鼠中，SBI-364治疗未实现肿瘤缩小，提示TGR5抑制主要通过调节胆汁酸-免疫细胞相互作用来减缓肿瘤进展。与载体处理的肿瘤相比，经SBI-364处理的小鼠肿瘤中表达白细胞介素10的免疫抑制性巨噬细胞和M-MDSCs显著减少。此外，经胆汁酸处理的M-MDSCs对CD8+ T细胞增殖和功能的抑制增强，而这一效应可被SBI-364共处理所消除。
结论：我们证明，TGR5抑制代表了一种在多种免疫健全的临床前CCA模型中具有前景的治疗策略。我们证明，胆汁酸-TGR5轴通过免疫抑制性髓系细胞促进CCA进展。具体而言，TGR5信号传导增强M-MDSCs的免疫抑制能力，促成一个促进肿瘤进展的免疫抑制性微环境。这些结果确立了TGR5作为克服胆管癌免疫逃逸的合理治疗靶点。
查看英文原文 English abstract
Background: Cholangiocarcinoma (CCA) is an aggressive hepatobiliary malignancy with limited treatment options. CCA exhibits a distinct desmoplastic and tolerogenic tumor immune microenvironment (TIME) characterized by elevated bile acid concentrations resulting from obstructive cholestasis and dysregulated bile acid metabolism. TGR5 is an essential component of bile acid signaling. We hypothesize that bile acids promote CCA progression by establishing an immunosuppressive TIME through TGR5 signaling, which can be therapeutically targeted using SBI-364, a novel potent small molecule TGR5 inhibitor.
Methods: Single-cell RNA sequencing (scRNA-seq) of immune cells from human intrahepatic (iCCA) and perihilar (pCCA) CCA tumors were conducted. Therapeutic studies were performed using syngeneic murine models of iCCA (PMID: 38458319), a novel syngeneic model of pCCA, and patient-derived xenograft (PDX) models. In collaboration with Sanford Burnham Prebys, SBI-364, a first in-class competitive TGR5 antagonist, was assessed in vivo. Additionally, we performed co-culture experiments with bile acid +/- SBI-364-treated murine bone marrow-derived monocytic myeloid-derived suppressor cells (M-MDSCs) and CD8 + T cells to assess functional immunosuppressive effects.
Results: Human scRNA-seq revealed significantly increased TGR5 (GPBAR1) expression predominantly in myeloid cell populations within the CCA TIME. SBI-364 treatment significantly reduced tumor burden in both syngeneic orthotopic iCCA models and a novel pCCA model that recapitulates the anatomic characteristics of perihilar CCA. In contrast, NOD/SCID mice bearing PDX535 (predicted sensitive) and PDX136 (predicted resistant), SBI-364 treatment did not achieve tumor reduction, suggesting that TGR5 inhibition predominantly attenuates tumor progression through modulation of bile acid-immune cell interactions. SBI-364 treated murine tumors had a significant reduction in immunosuppressive macrophages expressing interleukin-10 and M-MDSCs compared to vehicle treated tumors. Furthermore, bile acid-treated M-MDSCs exhibited enhanced suppression of CD8 + T cell proliferation and function, an effect that was abrogated by SBI-364 co-treatment.
Conclusion: We demonstrate that TGR5 inhibition represents a promising therapeutic strategy across multiple immunocompetent preclinical CCA models. We demonstrate that the bile-acid TGR5 axis promotes CCA progression via immunosuppressive myeloid cells. Specifically, TGR5 signaling potentiates the immunosuppressive capacity of M-MDSCs, contributing to an immunosuppressive niche that facilitates tumor progression. These results establish TGR5 as a rational therapeutic target for overcoming immune evasion in cholangiocarcinoma.
利益披露 Disclosure
E. Ozmert, None..
J. R. Willhite, None..
D. Carlson, None..
J. Covel, None..
R. Ramachandra, None.