Biology subjects

Lim, W.-W.

Publications and source records attributed to Lim, W.-W..

12 recordsLinked to original sources

bioRxiv2026

Recessive POPDC1 Truncation Causes Lethal Short-QT Pattern Arrhythmogenic Cardiomyopathy with Multi-Ion Channel Remodeling and Ankyrin-G Scaffold Disruption

AimsBiallelic variants in Popeye domain containing 1 (POPDC1) classically cause limb-girdle muscular dystrophy, but their impact on cardiac system remains unclear. We investigated the functional consequence of a POPDC1 frameshift variant (c.448delT), first identified in a consanguineous family with arrhythmogenic cardiomyopathy (ACM) and sudden death. Methods and resultsComprehensive clinical and genetic evaluation was followed by mechanistic studies in an orthologous Popdc1 knock-in rat model. Functional characterization included biotelemetry and programed electrical stimulation, optical mapping, patch clamp, intracellular Ca2+ imaging, proteomics, and oxidative stress assays. Homozygous mutants (Popdc1fs/fs) exhibited a shortened QTc interval and high incidence of ventricular tachycardia compared to wild-type (Popdc1+/+). Urethane anesthesia provoked second-degree AV block in all 10 Popdc1fs/fs rats but in only 1 of 9 Popdc1+/+ littermates. Optical mapping demonstrated abbreviated action potentials, slowed conduction velocity, and inducible polymorphic VT. Patch clamp confirmed accelerated repolarization, with upregulated transient outward potassium currents (Ito) and L-type calcium currents (ICa, L), but downregulated peak sodium currents (INa). Multi-omics and ultrastructural analyses revealed a post-translational collapse of intercalated disc: POPDC1 loss destabilized Ankyrin-G and its membrane-anchored cargo, Nav1.5, coinciding with enhanced Kv4.3 and Cav1.2 protein levels. These disruptions create a convergence of delayed conduction and shortened refractoriness, forming substrate for malignant re-entry. ConclusionWe defined a recessive short-QT ACM leading to potentially fatal arrhythmias caused by biallelic POPDC1 truncation driving Ankyrin-G disruption, manifesting as a triad: (1) bradycardia/AV block, (2) accelerated repolarization as short-QT pattern/diffuse T-wave flattening or inversion, and (3) progressive cardiomyopathy and sudden death. Whats new?O_LIWe define a novel diagnostic triad for recessive short-QT arrhythmogenic cardiomyopathy (rSQT-ACM) in a loss-of-function POPDC1 truncation: (1) early-onset bradyarrhythmia (sinus bradycardia or AV block); (2) a paradoxical short-QT interval with maladaptive rate response/diffuse T-wave flattening or inversion; and (3) progressive cardiomyopathy accompanied accompanied by with SCD. C_LIO_LIMechanistically, biallelic POPDC1 truncation induces collapse of the POPDC1-AnkG hub, which triggers a unique "opposing remodeling" phenotype (severe INa reduction coupled with paradoxical upregulation of Kv4.3-mediated Ito), and established a unified "slow-conduction, short-wavelength" substrate that underpins malignant re-entry. C_LIO_LIImplications for safety and device therapy: Nav1.5 deficiency indicates that sodium channel blockers may be contraindicated, and early ICD implantation may be preferable to bradycardia pacing. C_LIO_LIMechanism-directed treatments: POPDC1s recessive inheritance and small gene size make it a strong candidate for AAV-mediated gene supplementation aimed at restoring the intercalated disc architecture and ion-channel anchoring. C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=76 SRC="FIGDIR/small/710328v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@1012d79org.highwire.dtl.DTLVardef@5073dcorg.highwire.dtl.DTLVardef@1e69bc2org.highwire.dtl.DTLVardef@fc15ec_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG

genetics↗

bioRxiv2023

Fibroblast-derived IL-11 is a driver and therapeutic target in Peutz-Jeghers syndrome polyposis

Peutz-Jeghers syndrome (PJS) is associated with early-onset and recurring gastrointestinal hamartomatous polyposis caused by hereditary inactivating mutations in the tumor suppressor gene LKB1 (STK11). Due to lack of efficient prophylactic therapies PJS patients require regular surgical interventions and have an increased risk of cancer. LKB1-deficient fibroblasts have been identified as drivers of polyposis, but a safely druggable target remains to be identified. Here we investigate tumorigenic mechanisms in PJS polyps using single-cell RNA sequencing of predisposed and tumor tissue and identified a ST2-expressing crypt top fibroblast (CTF) cluster enriched in polyps. The relevance of CTFs was supported by the fast polyposis following deletion of Lkb1 in CTFs. The transcriptional signature characterizing the ST2+ fibroblasts (ST2-CTFs) was enriched in inflammation-associated fibroblasts, and PJS polyposis was exacerbated by inflammation. Cell-cell communication analysis identified the ST2-CTF signature gene interleukin 11 (IL-11) as an upstream regulator of the ST2-CTFs, and consistently, reprogramming toward ST2 fibroblasts in vitro was dependent on IL-11. Importantly, a neutralizing IL-11 antibody efficiently reduced the tumor burden in a PJS mouse model. In summary, our results reveal ST2+ tumorigenic fibroblasts as drivers of PJS polyposis and identify IL-11 as the key mediator and a potential therapeutic target in PJS.

cancer biology↗

bioRxiv2023

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

molecular biology↗

bioRxiv2023

Inhibition of an immunometabolic axis of mTORC1 activation extends mammalian healthspan

Human ageing is associated with metabolic dysfunction, sarcopenia and frailty that taken together reduce healthspan. For age-associated diseases and lifespan, ERK, AMPK and mTORC1 represent critical pathways, across species1-7. Here we examined the hypothesis that IL11, recently shown to regulate ERK/mTORC1, is an inflammaging factor important for healthspan. As mice age, IL11 is progressively upregulated in liver, skeletal muscle, and fat to stimulate an ERK/AMPK/mTORC1 axis of cellular, tissue- and organismal-level ageing pathologies. In old mice, deletion of Il11 or Il11ra1 protects against metabolic multi-morbidity, sarcopenia, and frailty. Administration of anti-IL11 therapy to elderly mice for six months reactivates an age-repressed program of white fat beiging, reverses metabolic dysfunction, restores muscle function, and reduces frailty. Across studies, inhibition of IL11 lowers epigenetic age, reduces telomere attrition, and preserves mitochondrial function. Towards clinical translation, we generated, humanised, and engineered a neutralising, high-affinity IL11 antibody. These studies identify IL11 as a key inflammaging factor and therapeutic target for mammalian healthspan.

molecular biology↗

bioRxiv2023

Cardiomyocyte-restricted expression of IL11 causes cardiac fibrosis, inflammation, and dysfunction.

AbstractBackground: Cardiac fibrosis is a common pathological process in heart disease and represents a therapeutic target. TGF{beta} is the canonical driver of cardiac fibrosis and was recently shown to be dependent on IL11 for its profibrotic effects in fibroblasts. In the opposite direction, recombinant human IL11 has been reported as anti-fibrotic and also anti- inflammatory in the mouse heart. Objectives: In this study, we determined the effects of IL11 expression in cardiomyocytes on cardiac pathobiology and function. Methods: We used the Cre-loxP system to generate a tamoxifen-inducible mouse with cardiomyocyte-restricted murine Il11 expression. Using protein assays, bulk RNA-sequencing, and in vivo imaging we analysed the effects of IL11 on myocardial fibrosis, inflammation and cardiac function and challenge previous reports suggesting cardioprotective potential of IL11. Results: TGF{beta} stimulation of cardiomyocytes caused Il11 upregulation. As compared to wild-type controls, Il11 expressing hearts demonstrated severe cardiac fibrosis and inflammation that was associated with the upregulation of cytokines, chemokines, complement factors and increased inflammatory cells. IL11 expression also activated a programme of endothelial-to- mesenchymal transition and resulted in left ventricular dysfunction. Conclusion: Our data define species matched IL11 as strongly profibrotic and proinflammatory when secreted from cardiomyocytes and further establish IL11 as a disease factor.

molecular biology↗

bioRxiv2022

Interleukin-11 causes alveolar type 2 cell dysfunction and prevents alveolar regeneration

Following lung injury, alveolar regeneration is characterized by the transformation of alveolar type 2 (AT2) cells, via a transitional KRT8+ state, into alveolar type 1 (AT1) cells. In lung disease, dysfunctional intermediate cells accumulate, AT1 cells are diminished and fibrosis occurs. Using single cell RNA sequencing datasets of human interstitial lung disease, we found that interleukin-11 (IL11) is specifically expressed in aberrant KRT8 expressing KRT5-/KRT17+ and basaloid cells. Stimulation of AT2 cells with IL11 or TGF{beta}1 caused EMT, induced KRT8+ and stalled AT1 differentiation, with TGF{beta}1 effects being IL11 dependent. In bleomycin injured mouse lung, IL11 was increased in AT2-derived KRT8+ cells and deletion of Il11ra1 in lineage labeled AT2 cells reduced KRT8+ expression, enhanced AT1 differentiation and promoted alveolar regeneration, which was replicated in therapeutic studies using anti-IL11. These data show that IL11 maintains AT2 cells in a dysfunctional transitional state, impairs AT1 differentiation and blocks alveolar regeneration across species. TeaserInterleukin-11 stalls type 2-to-type 1 alveolar epithelial cell differentiation and prevents lung regeneration

immunology↗

bioRxiv2022

IL11 stimulates IL33 expression and proinflammatory fibroblast activation

Interleukin 11 (IL11) is upregulated in inflammatory conditions where it is believed to have anti-inflammatory activity. However, recent studies suggest instead that IL11 may promote inflammation, via the stroma. Here, we assessed whether IL11 is pro- or anti-inflammatory in fibroblasts. Primary cultures of human kidney, lung or skin fibroblasts were stimulated with IL11 that resulted in transient STAT3 phosphorylation and bi-modal ERK activation. RNA sequencing over a time course of IL11 stimulation revealed a robust short-lived transcriptional response, which was enriched for gene set hallmarks of inflammation and characterized by upregulation of SERPINB2, TNFRSF18, IL33, CCL20, IL1RL1, CXCL3/5/8, ICAM1 and IL11 itself. IL33 was the most upregulated signaling factor (38-fold, P=9.8x10-5) and IL1RL1, its cognate receptor, was similarly increased (18-fold, P=1.1x10-34). In proteomic studies, IL11 triggered a proinflammatory secretome with notable upregulation of IL8, IL6, MCP1, CCL20 and CXCL1/5/6, which are important chemotaxins for neutrophils, monocytes and lymphocytes. IL11 induced IL33 expression across fibroblast types and inhibition of STAT3, but not MEK/ERK, prevented this. These data establish IL11 as pro-inflammatory with specific importance for priming the IL33 alarmin response in inflammatory fibroblasts.

molecular biology↗

bioRxiv2022

IL11 stimulates ERK/P90RSK to inhibit LKB1/AMPK and activate mTOR in hepatocytes, the stroma and cancer cells

Interleukin 11 (IL11) stimulates stromal cell activation but also causes hepatocyte metabolic dysfunction. The mechanisms underlying these seemingly unrelated processes are not known. Here we report that IL11-stimulated ERK/P90RSK activity causes the sequential phosphorylation of LKB1 (STK11) at S325 and S428, leading to its inactivation. This leads to a reduction in AMPK activity whilst concomitantly activating mTOR in human fibroblasts, hepatic stellate cells, hepatocytes and cancer cells. In fibroblasts and hepatic stellate cells, IL11-mediated LKB1/AMPK inhibition causes myofibroblast transformation whereas in hepatocytes it inhibits autophagy and fatty acid oxidation and is toxic. Across cell types, the self-amplifying loop of autocrine IL11 activity was inhibited by AMPK activation with metformin, AICAR or 991. In mice on a western diet with fructose, anti-IL11 therapy or hepatocyte-specific deletion of Il11ra1 rescues LKB1/AMPK activity and reduces NASH. In contrast, restoration of IL11 signalling in hepatocytes of mice with global Il11ra1 deletion inactivates LKB1/AMPK and exacerbates NASH. These data show that LKB1, an important tumour suppressor and master kinase, is not constitutively active and identify the IL11/LKB1/AMPK/mTOR axis as a point of signalling convergence for epithelial homeostasis, fibrogenesis, immunometabolism and cancer.

molecular biology↗

bioRxiv2020

Autocrine IL11 cis-signaling in hepatocytes is an initiating nexus between lipotoxicity and non-alcoholic steatohepatitis

Background and aimsIL11 signaling is important in non-alcoholic steatohepatitis (NASH) but how it contributes to NASH pathologies beyond fibrosis is not known. Here we investigate the role of IL11 signaling in hepatocyte lipotoxicity. MethodsHepatocytes were stimulated with IL6, IL11, HyperIL6, or HyperIL11 alone or in the presence of soluble gp130 (sgp130) or soluble IL11RA (sIL11RA), or loaded with palmitate in the presence of IgG or anti-IL11RA (X209) antibodies or sgp130. Effects were assessed using colorimetric ALT, GSH, or ELISA assays, immunoblots, and flow cytometry. The relative contributions of IL11 cis-versus -trans signaling in vivo was assessed in two preclinical NASH models using a high fat methionine/choline deficient diet or a Western diet with liquid fructose in C57BL6/Ntac mice injected with AAV8-Alb-Cre, AAV8-Alb-sgp130, in mice with hepatocyte-specific deletion of Il11ra (CKO), and in mice with global deletion of Il11ra injected with AAV8-Alb-mIl11ra or AAV8-Alb-sIl11ra. Livers and serum were collected; serum samples were analyzed using biochemistry and liver tissues were analyzed by histology, qPCR, immunobloting, hydroxyproline, and GSH assays. ResultsWe show that lipid-laden hepatocytes secrete IL11, which acts via autocrine cis-signaling to cause lipoapoptosis. IL11 causes lipotoxic hepatocyte death through activation of non-canonical signaling pathways and increased NOX4-derived reactive oxygen species. In two preclinical models, hepatocyte-specific deletion of Il11ra1 protects mice from all aspects of NASH with beneficial effects on body weight. In accordance, restoration of IL11 cis-signaling in hepatocytes only in mice globally deleted for Il11ra1 reconstitutes steatosis and inflammation. Throughout, we found no evidence to support the existence of IL6 or IL11 trans-signaling in the liver. ConclusionWe conclude that autocrine IL11-mediated cell death underlies hepatocyte lipotoxicity and that liver fibrosis and inflammation occur subsequently. These data highlight a new disease mechanism for the transition from compensated fatty liver disease to NASH.

molecular biology↗

bioRxiv2019

Redefining Interleukin 11 as a regeneration-limiting hepatotoxin

Acetaminophen (APAP) overdose is a leading cause of untreatable liver failure. In the mouse model of APAP-induced liver injury (AILI), the administration of recombinant human interleukin 11 (rhIL11) is protective. Here we show that the beneficial effect of rhIL11 in the mouse is due to its unexpected and paradoxical inhibition of endogenous mouse IL11 activity. Contrary to the accepted paradigm IL11 is a potent hepatotoxin across species, which is secreted from damaged hepatocytes to drive an autocrine loop of NOX4 and JNK-dependent apoptosis. Mice with hepatocyte-specific Il11 expression spontaneously develop liver failure whereas those with Il11ra1 deletion are remarkably protected from AILI. Neutralizing anti-IL11R antibodies administered to moribund mice 10 hours following a lethal APAP overdose results in 90% survival that is associated with very large liver regeneration. Our data overturn a misconception, identify a new disease mechanism and suggest IL11 as a therapeutic target for liver regeneration.

physiology↗

bioRxiv2019

Interleukin 11 expression causes murine inflammatory bowel disease

Interleukin 11 (IL11) is a profibrotic cytokine, secreted by myofibroblasts and damaged epithelial cells. Smooth muscle cells (SMCs) also secrete IL11 under pathological conditions and express the IL11 receptor. Here we examined the effects of SMC-specific, conditional expression of murine IL11 in a transgenic mouse (Il11SMC). Within days of transgene activation, Il11SMC mice developed loose stools and progressive bleeding and rectal prolapse, which was associated with a 65% mortality by two weeks. The bowel of Il11SMC mice was inflamed, fibrotic and had a thickened wall, which was accompanied by activation of ERK and STAT3. In other organs, including heart, lung, liver, kidney and skin there was a phenotypic spectrum of fibro-inflammation, together with consistent ERK activation. To investigate further the importance of stromal-derived IL11 in the inflammatory bowel phenotype we used a second model with fibroblast-specific expression of IL11, the Il11Fib mouse. This additional model largely phenocopied the Il11SMC bowel phenotype. These data show that IL11 secretion from the stromal niche is sufficient to drive inflammatory bowel disease in mice. Given that IL11 expression in colonic stromal cells predicts anti-TNF therapy failure in patients with ulcerative colitis or Crohns disease, we suggest IL11 as a therapeutic target for inflammatory bowel disease.

pathology↗

bioRxiv2018

IL-11 is a therapeutic target in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) remains a progressive disease despite best medical management. We previously identified IL-11 as a critical factor for cardiovascular fibrosis and examine here its role in pulmonary fibrosis. IL-11 is consistently upregulated in IPF genomic datasets, which we confirmed by histology. Pulmonary fibroblasts stimulated with IL-11 transform into invasive myofibroblasts whereas fibroblasts from Il11ra deleted mice did not respond to pro-fibrotic stimuli. In the mouse, injection of recombinant Il-11 or fibroblast-specific expression of Il-11 caused pulmonary fibrosis. We then generated a neutralising IL-11 binding antibody that blocks lung fibroblast activation across species. In a mouse model of IPF, anti-IL-11 therapy attenuated lung fibrosis and specifically blocked Erk activation. These data prioritise IL-11 as an accessible drug target in IPF.\n\nOne Sentence SummaryNon-canonical IL-11 signalling is a central hallmark of idiopathic pulmonary fibrosis and represents a novel target for antibody therapies.

molecular biology↗