Interleukin 11 therapy causes acute left ventricular dysfunction.

AIMS: Interleukin 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 and severe cardiac side effects. Here we aim to identify, for the first time, direct cardiomyocyte toxicities associated with IL11, which was previously believed cardioprotective. METHODS AND RESULTS: We 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 (CMKO) 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. Injection of rmIL11 caused acute and dose-dependent impairment of left ventricular ejection fraction (saline: 62.4% ± 1.9; rmIL11: 32.6% ± 2.9, p<0.001, n=5). Following rmIL11 injection, myocardial STAT3 and JNK phosphorylation were increased and bulk RNA-seq revealed upregulation of pro-inflammatory pathways (TNFα, NFκB 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 the Ankrd1 and Nppb genes and loci enriched for 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. CONCLUSIONS: Injection of IL11 directly activates IL11RA/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.

A γA-Crystallin Mouse Mutant Secc with Small Eye, Cataract and Closed Eyelid.

Cataract is the most common cause of visual loss in humans. A spontaneously occurred, autosomal dominant mouse mutant Secc, which displayed combined features of small eye, cataract and closed eyelid was discovered in our laboratory. In this study, we identified the mutation and characterized the cataract phenotype of this novel Secc mutant. The Secc mutant mice have eyelids that remain half-closed throughout their life. The mutant lens has a significant reduction in size and with opaque spots clustered in the centre. Histological analysis showed that in the core region of the mutant lens, the fiber cells were disorganized and clefts and vacuoles were observed. The cataract phenotype was evident from new born stage. We identified the Secc mutation by linkage analysis using whole genome microsatellite markers and SNP markers. The Secc locus was mapped at chromosome 1 flanked by SNPs rs3158129 and rs13475900. Based on the chromosomal position, the candidate cataract locus γ-crystallin gene cluster (Cryg) was investigated by sequencing. A single base deletion (299delG) in exon 3 of Cryga which led to a frame-shift of amino acid sequence from position 91 was identified. As a result of this mutation, the sequences of the 3rd and 4th Greek-key motifs of the γA-crystallin are replaced with an unrelated C-terminal peptide of 75 residues long. Coincidentally, the point mutation generated a HindIII restriction site, allowing the identification of the CrygaSecc mutant allele by RFLP. Western blot analysis of 3-week old lenses showed that the expression of γ-crystallins was reduced in the CrygaSecc mutant. Furthermore, in cell transfection assays using CrygaSecc mutant cDNA expression constructs in 293T, COS-7 and human lens epithelial B3 cell lines, the mutant γA-crystallins were enriched in the insoluble fractions and appeared as insoluble aggregates in the transfected cells. In conclusion, we have demonstrated that the Secc mutation leads to the generation of CrygaSecc proteins with reduced solubility and prone to form aggregates within lens cells. Accumulation of mutant proteins in the lens fibers would lead to cataract formation in the Secc mutant.

Characterization of white matter injury in a hypoxic-ischemic neonatal rat model by diffusion tensor MRI.

BACKGROUND AND PURPOSE: We evaluate white matter (WM) injury after hypoxic-ischemic (HI) insult in a neonatal rat model using diffusion tensor imaging (DTI) to determine whether lambda(parallel) and lambda(perpendicular) are able to characterize type and severity of brain damage. METHODS: Eighteen 7-day-old Sprague-Dawley rats underwent unilateral ligation of left common carotid artery followed by 50 minutes (n=9) or 90 minutes (n=9) of hypoxia at 37 degrees C. Rats were divided into 2 groups, according to absence (group A, n=11) or presence (group B, n=7) of cystic lesions on D7 post-HI T2-weighted imaging. DTI was performed for all rats at D1 and for group A rats at D7 post-HI. Signal intensity of ipsilateral and contralateral external capsule (EC) on D1 was compared by paired t test, with histological correlation. RESULTS: Group A rats had significantly reduced FA, elevated trace, elevated lambda(perpendicular), and similar lambda(parallel) on D1 in the ipsilateral compared to contralateral EC, whereas group B rats had significant reduction in all parameters in the ipsilateral EC. Elevated trace normalized on D7 in group A rats. Histopathologic results demonstrated reduced myelination in group A noncystic HI and severe necrosis in group B cystic HI. CONCLUSIONS: Increased lambda(perpendicular) with no significant change in lambda(parallel) appears to characterize noncystic WM injury with reduced myelination, whereas reduction in both lambda(parallel) and lambda(perpendicular) characterize severe damage with loss of structural integrity and necrosis. Combining with FA and trace, lambda(parallel) and lambda(perpendicular) provide additional information which reflects type and severity of HI injury.