Haematology Oncology Group, Cancer Sciences Unit, Cancer Research UK and NIHR Experimental Cancer Medicine Centres, Faculty of Medicine, University of Southampton, Southampton, UK.
Wessex Investigational Sciences Hub laboratory, Cancer Sciences Unit, Cancer Research UK and NIHR Experimental Cancer Medicine Centres, Faculty of Medicine, University of Southampton, Southampton, UK.
Leukemia. 2017 Aug;31(8):1686-1694. doi: 10.1038/leu.2016.356. Epub 2016 Nov 28.
Chronic lymphocytic leukemias (CLLs) with unmutated (U-CLL) or mutated (M-CLL) IGHV have variable features of immunosuppression, possibly influenced by those CLL cells activated to produce interleukin 10 (IL-10). The two subsets differ in their levels of anergy, defined by low surface immunoglobulin M levels/signaling capacity, and in their DNA methylation profile, particularly variable in M-CLL. We have now found that levels of IL-10 produced by activated CLL cells were highly variable. Levels were higher in M-CLL than in U-CLL and correlated with anergy. DNA methylation analysis of IL10 locus revealed two previously uncharacterized 'variably methylated regions' (CLL-VMRs1/2) in the gene body, but similarly low methylation in the promoter of both U-CLL and M-CLL. CLL-VMR1/2 methylation was lower in M-CLL than in U-CLL and inversely correlated with IL-10 induction. A functional signal transducer and activator of transcription 3 (STAT3) binding site in CLL-VMR2 was confirmed by proximity ligation and luciferase assays, whereas inhibition of SYK-mediated STAT3 activation resulted in suppression of IL10. The data suggest epigenetic control of IL-10 production. Higher tumor load may compensate the reduced IL-10 production in U-CLL, accounting for clinical immunosuppression in both subsets. The observation that SYK inhibition also suppresses IL-10 provides a potential new rationale for therapeutic targeting and immunological rescue by SYK inhibitors in CLL.
慢性淋巴细胞白血病（CLL）分为未突变（U-CLL）和突变（M-CLL）两种，前者免疫抑制特征更为明显，这可能与 CLL 细胞激活并产生白细胞介素 10（IL-10）有关。这两种亚型在无反应性（定义为表面免疫球蛋白 M 水平/信号转导能力低）方面存在差异，且 DNA 甲基化模式也存在差异，其中 M-CLL 的变化更为明显。我们发现激活的 CLL 细胞产生的 IL-10 水平存在高度变异性。M-CLL 中的水平高于 U-CLL，与无反应性相关。对 IL10 基因座的 DNA 甲基化分析显示，基因体中存在两个以前未被描述的“可变甲基化区域”（CLL-VMR1/2），但 U-CLL 和 M-CLL 的启动子中同样存在低甲基化。M-CLL 中的 CLL-VMR1/2 甲基化程度低于 U-CLL，且与 IL-10 诱导呈负相关。通过接近连接和荧光素酶测定证实了 CLL-VMR2 中存在功能性信号转导和转录激活因子 3（STAT3）结合位点，而抑制 SYK 介导的 STAT3 激活可抑制 IL10。这些数据表明 IL-10 产生受到表观遗传控制。较高的肿瘤负荷可能补偿了 U-CLL 中 IL-10 产生的减少，这解释了两种亚型的临床免疫抑制。抑制 SYK 还可抑制 IL-10 的发现为 SYK 抑制剂在 CLL 中的治疗靶向和免疫拯救提供了新的潜在依据。
