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

BackgroundInterleukin 11 (IL11) was initially thought important for platelet production, which led to recombinant IL11 being developed as a drug to treat thrombocytopenia. IL11 was later found to be redundant for haematopoiesis and its use in patients is associated with unexplained cardiac side effects. Here we identify previously unappreciated and direct cardiomyocyte toxicities associated with IL11 therapy. MethodsWe injected recombinant mouse lL11 (rmIL11) into mice and studied its molecular effects in the heart using immunoblotting, qRT-PCR, bulk RNA-seq, single nuclei RNA-seq (snRNA-seq) and ATAC-seq. The physiological impact of IL11 was assessed by echocardiography in vivo and using cardiomyocyte contractility assays in vitro. To determine the activity of IL11 specifically in cardiomyocytes we made two cardiomyocyte-specific Il11ra1 knockout mouse models using either AAV9-mediated and Tnnt2-restricted (vCMKO) or Myh6 (m6CMKO) Cre expression and an Il11ra1 floxed mouse strain. In pharmacologic studies, we studied the effects of JAK/STAT inhibition on rmIL11-induced cardiac toxicities. ResultsInjection of rmIL11 caused acute and dose-dependent impairment of left ventricular ejection fraction (saline (2 {micro}L/kg), 60.4%{+/-}3.1; rmIL11 (200 mcg/kg), 31.6%{+/-}2.0; p<0.0001, n=5). Following rmIL11 injection, myocardial STAT3 and JNK phosphorylation were increased and bulk RNA-seq revealed upregulation of pro-inflammatory pathways (TNF, NF{kappa}B and JAK/STAT) and perturbed calcium handling. SnRNA-seq showed rmIL11-induced expression of stress factors (Ankrd1, Ankrd23, Xirp2), activator protein-1 (AP-1) transcription factor genes and Nppb in the cardiomyocyte compartment. Following rmIL11 injection, ATAC-seq identified epigenetic enrichment of the Ankrd1 and Nppb genes and stress-responsive, AP-1 transcription factor binding sites. Cardiomyocyte-specific effects were examined in vCMKO and m6CMKO mice, which were both protected from rmIL11-induced left ventricular impairment and molecular pathobiologies. In mechanistic studies, inhibition of JAK/STAT signalling with either ruxolitinib or tofacitinib prevented rmIL11-induced cardiac dysfunction. ConclusionsInjection of IL11 directly activates JAK/STAT3 in cardiomyocytes to cause acute heart failure. Our data overturn the earlier assumption that IL11 is cardioprotective and explain the serious cardiac side effects associated with IL11 therapy, which questions its continued use in patients. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIInjection of IL11 to mice causes acute and dose-dependent left ventricular impairment C_LIO_LIIL11 activates JAK/STAT3 in cardiomyocytes to cause cell stress, inflammation and impaired calcium handling C_LIO_LIThese data identify, for the first time, that IL11 is directly toxic in cardiomyocytes, overturning the earlier literature that suggested the opposite C_LI What are the clinical implications?O_LIRecombinant human IL11 (rhIL11) is used as a drug to increase platelets in patients with thrombocytopenia but this has severe and unexplained cardiac side effects C_LIO_LIWe show that IL11 injection causes cardiomyocyte dysfunction and heart failure, which explains its cardiac toxicities that were previously thought non-specific C_LIO_LIThese findings have immediate translational implications as they question the continued use of rhIL11 in patients around the world C_LI