Altered activation and transcriptional profile in monocytes and CD8+ T cells in checkpoint inhibitor-related hepatitis

Abstract Background & Aims: Checkpoint inhibitor-related hepatitis (CPI-Hep) is an emerging clinical challenge. We aim to gain insights into the immunopathology of CPI-Hep by comprehensive characterisation of myeloid and lymphoid subsets. Methods: CPI-treated patients with or without related hepatitis (CPI-Hep; n=22 and CPI-noHep; n=7) were recruited. Phenotypic and transcriptional-profiling of peripheral immune subsets was performed and compared with 19 healthy controls (HC). In vitro monocyte-derived macrophages (MoMF) were assessed for activation and cytokine production. CCR2, CD68, CD3, CD8 and granzyme B expression was assessed using immunohistochemistry (n=4). Results: A significant total monocyte depletion was observed in CPI-Hep compared with HC (p=0.04), along with a proportionate increase in the classical monocyte population (p=0.0002) and significant upregulation of CCR2, CD163 and downregulation of CCR7. Soluble CD163 levels were significantly elevated in CPI-Hep compared with HC (p<0.0001). In vitro MoMF from CPI-Hep showed enhanced production of pro-inflammatory cytokines. CD8+ T cells demonstrated increased perforin, granzyme B, ICOS and HLA-DR expression in CPI-Hep. Transcriptional profiling supported activated monocyte and enhanced effector CD8+ T cell populations in CPI-Hep. Immunohistochemistry demonstrated co-localisation of CD8+/granzyme B+ T cells with CD68+/CCR2+ macrophages in CPI-Hep liver tissue. Conclusions: CPI-Hep is associated with an activation of peripheral monocytes and enhanced cytotoxic, effector phenotype of CD8+ T cells. These changes were reflected by liver inflammation composed of CCR2+ macrophage and CD8+ T cells.研究背景与目的：免疫检查点抑制剂相关肝炎 (Checkpoint inhibitor-related hepatitis, CPI-Hep) 是一类新兴的临床难题。本研究旨在通过对髓系与淋巴系细胞亚群开展全面表征，深入解析CPI-Hep的免疫病理机制。 研究方法：本研究招募了接受免疫检查点抑制剂治疗且合并/未合并相关肝炎的患者（CPI-Hep组：n=22；CPI-noHep组：n=7），同时纳入19名健康对照 (Healthy Controls, HC)。对三组受试者的外周免疫细胞亚群进行表型分析与转录谱分析 (transcriptional-profiling)，并开展组间比较；此外，对体外培养的单核细胞源性巨噬细胞 (Monocyte-derived macrophages, MoMF) 的活化状态与细胞因子分泌情况进行检测；采用免疫组化 (immunohistochemistry) 检测4份样本中CCR2、CD68、CD3、CD8及颗粒酶B (granzyme B) 的表达水平。 研究结果：与健康对照相比，CPI-Hep组患者外周血单核细胞总数显著减少（p=0.04），同时经典单核细胞占比呈比例升高（p=0.0002），且CCR2、CD163的表达显著上调，CCR7的表达显著下调。CPI-Hep组患者血清可溶性CD163水平显著高于健康对照（p<0.0001）。体外实验显示，CPI-Hep组来源的单核细胞源性巨噬细胞促炎细胞因子分泌水平显著增强。CD8+ T细胞的穿孔素、颗粒酶B、ICOS及HLA-DR表达水平在CPI-Hep组中均显著升高。转录谱分析结果证实，CPI-Hep组患者外周血中存在活化的单核细胞群与功能增强的效应性CD8+ T细胞群。免疫组化结果显示，CPI-Hep患者肝组织中CD8+/颗粒酶B+ T细胞与CD68+/CCR2+巨噬细胞存在共定位现象。 研究结论：CPI-Hep与外周血单核细胞活化以及CD8+ T细胞细胞毒性效应表型增强密切相关。上述免疫异常可通过以CCR2+巨噬细胞与CD8+ T细胞浸润为核心的肝脏炎症得以体现。