Interleukin 11 therapy causes acute heart failure and its use in patients should be reconsidered. Interleukin 11 therapy causes acute heart failure and its use in patients should be reconsidered

Background: Interleukin-11 (IL11) was initially identified as a fibroblast secreted factor that supports haematopoietic cell function. This led to its development as a drug to increase platelet counts in patients with thrombocytopenia. However, IL11 was later found redundant for hematopoiesis and its use in humans causes severe and unexplained cardiac side effects. Here we identify and dissect mechanisms underlying previously unappreciated cardiac toxicities associated with IL11 therapy. Methods: We injected recombinant mouse lL11 (rmIl11) at clinically relevant doses to study its effects on myocardial signalling using immunoblotting and genomic variation using qRT-PCR, RNA-seq and ATAC-seq. The physiological impact of Il11 was assessed by echocardiography in vivo and cardiomyocyte contractility assays in vitro. To determine the specific activity of IL11 in cardiomyocytes we generated two distinct cardiomyocyte-specific IL11 receptor knockout (CMKO) mouse models using either AAV9-mediated, Tnnt2-restricted (vCMKO) or mhy6 (m6CMKO) Cre expression in an Il11ra1 floxed mouse strain. In pharmacologic studies, we studied the effects of JAK/STAT inhibition following rmIl11 injection to mice.Results: Injection of rmIl11 to mice caused dose-dependent impairment of left ventricular ejection fraction (LVEF: saline, 64.2%±1.62; rmIl11 (50 mg/kg), 31.6±2.0; p<0.0001). RNA-seq of hearts one and three hours following rmIl11 injection revealed strong upregulation of the TNF, NFkB and JAK/STAT pathways as well as increased Nppa and Rrad levels. vCMKO mice were protected from rmIl11-induced STAT3 activation, Rrad upregulation and LV impairment. Similarly, m6CMKO mice of both sexes, were protected from the molecular, cellular and whole organ cardiac toxicities associated with Il11. Administration of JAK inhibitors prevented rmIl11-induced STAT3 activation and preserved cardiac function. Conclusions: Here we show that Il11 injection to mice is strongly proinflammatory in the heart. Furthermore, Il11 has profound negative inotropic effects that are mediated via its on-target activation of JAK/STAT3 signalling in cardiomyocytes. Our data explain the cardiac side effects associated with IL11 therapy and question its continued use in patients. Overall design: RNA-seq analysis of the hearts of male C57BL6/J mice injected with recombinant mouse IL11 at basline, 1 ,3 and 6 hours after injection.

背景：白细胞介素-11（Interleukin-11, IL11）最初被鉴定为一种支持造血细胞功能的成纤维细胞分泌因子，由此被开发为用于治疗血小板减少症患者以提升血小板计数的药物。然而后续研究发现IL11对造血过程并非必需，且其临床应用会引发严重且原因不明的心脏不良反应。本研究旨在阐明此前未被认知的、与IL11治疗相关的心脏毒性作用机制。

方法：我们以临床相关剂量注射重组小鼠IL11（recombinant mouse IL11, rmIL11），通过免疫印迹（immunoblotting）检测其对心肌信号通路的影响，并通过实时定量逆转录聚合酶链反应（qRT-PCR）、RNA测序（RNA-seq）及转座酶可及性测序（ATAC-seq）分析其基因组变异情况。通过在体超声心动图（echocardiography）及体外心肌细胞收缩力测定实验，评估IL11对心脏的生理影响。为明确IL11在心肌细胞中的特异性活性，我们在IL11受体α1（Il11ra1）条件性敲除（floxed）小鼠品系中，分别利用腺相关病毒血清型9（AAV9）介导的、受肌钙蛋白T2（Tnnt2）限制性启动子调控的Cre重组酶表达（vCMKO），以及受肌球蛋白重链6（mhy6）启动子调控的Cre重组酶表达（m6CMKO），构建了两种不同的心肌细胞特异性IL11受体敲除（cardiomyocyte-specific IL11 receptor knockout, CMKO）小鼠模型。在药理学研究中，我们检测了向小鼠注射rmIL11后给予Janus激酶/信号转导与转录激活子（JAK/STAT）抑制剂的干预效果。

结果：向小鼠注射rmIL11会引发剂量依赖性的左心室射血分数（left ventricular ejection fraction, LVEF）下降（生理盐水组：64.2%±1.62；rmIL11 50mg/kg组：31.6±2.0；p<0.0001）。在注射rmIL11后1小时及3小时对心脏组织进行RNA-seq分析，结果显示肿瘤坏死因子（TNF）、核因子κB（NFκB）及JAK/STAT通路显著上调，同时心房钠尿肽前体A（Nppa）及Ras相关结构域蛋白（Rrad）的表达水平升高。vCMKO小鼠可免受rmIL11诱导的STAT3激活、Rrad表达上调及左心室功能损伤。同样，两种性别的m6CMKO小鼠均能抵御IL11相关的分子、细胞及整体器官水平的心脏毒性。给予JAK抑制剂可阻断rmIL11诱导的STAT3激活，并维持心脏功能。

结论：本研究证实，向小鼠注射IL11可在心脏中引发强烈的促炎反应。此外，IL11具有显著的负性肌力作用，该作用通过心肌细胞中JAK/STAT3信号通路的靶向激活所介导。我们的研究结果解释了IL11治疗相关的心脏不良反应机制，并对其在临床患者中的持续应用提出了质疑。

整体实验设计：对雄性C57BL6/J小鼠注射重组小鼠IL11后，分别在基线、注射后1小时、3小时及6小时采集心脏组织进行RNA-seq分析。