Biology subjects

Schafer, S.

Publications and source records attributed to Schafer, S..

At least 19 recordsLinked to original sources

bioRxiv2026

Development of Visually Indistinguishable Acoustic Coupling Pads for Double-Blind Focused Ultrasound Neuromodulation Studies

BackgroundTranscranial focused ultrasound (tFUS) is an emerging noninvasive neuromodulation modality with the ability to target deep brain structures with high spatial precision. Despite its promise, rigorous evaluation of its efficacy is limited by the absence of reliable, fully double-blind sham methodologies. ObjectiveTo develop and validate a pair of visually and mechanically indistinguishable acoustic coupling pads that enable true double-blind tFUS neuromodulation studies by providing either efficient ultrasound transmission or robust ultrasound blocking without altering participant or operator experience. MethodsTwo coupling pads were engineered: a transmitting pad designed to allow <5% pressure amplitude loss relative to free-water propagation, and a non-transmitting pad designed to attenuate ultrasound by [≥]40 dB. Both pads used a Dragon Skin 10 NV silicone base and were identical in size, appearance, flexibility, and handling. The non-transmitting pad incorporated an encapsulated air-based blocking layer using an open-cell polyethylene foam insert. Acoustic performance was evaluated in a water tank using a 650 kHz BrainSonix transducer and a calibrated needle hydrophone. Sound speed of the silicone material was measured using pulse-echo techniques. ResultsTwenty-three matched transmitting and non-transmitting pad pairs were fabricated and tested. Transmitting pads demonstrated a mean attenuation of -0.41 {+/-} 0.53 dB, satisfying the design criterion of minimal acoustic loss.Non-transmitting pads demonstrated a mean attenuation of -48.61 {+/-} 4.33 dB, exceeding the required -40 dB threshold for effective sham conditions. The Dragon Skin 10 NV substrate exhibited a sound speed of 964.72 m/s and produced <2 mm axial focal shift for standard pad thicknesses, with no measurable change in focal width. Both pad types were visually and tactually indistinguishable, could not be differentiated by experienced operators or participants, and maintained mechanical integrity after repeated cleaning ConclusionThese acoustically engineered coupling pads provide a practical and validated solution for achieving true single- and double-blind conditions in tFUS neuromodulation studies. By preserving identical sensory and procedural experiences while enabling precise control over ultrasound transmission, this approach addresses a critical methodological gap in human ultrasound neuromodulation research.

bioengineering↗

bioRxiv2025

A scalable human-zebrafish xenotransplantation model reveals gastrosome-mediated processing of dying neurons by human microglia

Microglia engulf dying neurons through efferocytosis, a critical function in both development and disease. How microglia process the engulfed neuronal material--especially lipids--remains poorly understood, despite its central role in neurodegeneration. Thus, we developed HuZIBRA, a scalable in vivo xenotransplantation model in which human iPSC-derived microglia-like cells (iMGLs) are introduced into the developing zebrafish brain (zf-hiMG), a system characterized by high levels of neuronal cell death and amenable to precise genetic and pharmacological manipulation. We show that human microglia-like cells recognize and engulf apoptotic zebrafish neurons, indicating conserved efferocytic mechanisms. In these cells, engulfed neuronal material accumulates into a distinct, lipid-rich intracellular compartment, the gastrosome, which we also observed in iMGLs placed in a human brain-like environment. The size of the human gastrosome dynamically reflects neuronal cell death levels and is regulated by key genes, including TREM2 and SLC37A2. Pharmacological inhibition of the cholesterol transporter NPC1 induces gastrosome expansion and lipid accumulation, recapitulating pathological features of Niemann-Pick disease type C. Thus, HuZIBRA provides a powerful in vivo platform to uncover cell-autonomous adaptive responses of human microglia to apoptotic and metabolic stress, with the gastrosome emerging as a key integrator of neuronal debris processing and disease-relevant lipid metabolism.

cell biology↗

bioRxiv2024

Neural crest and periderm-specific requirements of Irf6 during neural tube and craniofacial development

IRF6 is a key genetic determinant of syndromic and non-syndromic cleft lip and palate. The ability to interrogate post-embryonic requirements of Irf6 has been hindered, as global Irf6 ablation in the mouse causes neonatal lethality. Prior work analyzing Irf6 in mouse models defined its role in the embryonic surface epithelium and periderm where it is required to regulate cell proliferation and differentiation. Several reports have also described Irf6 gene expression in other cell types, such as muscle, and neuroectoderm. However, analysis of a functional role in non-epithelial cell lineages has been incomplete due to the severity and lethality of the Irf6 knockout model and the paucity of work with a conditional Irf6 allele. Here we describe the generation and characterization of a new Irf6 floxed mouse model and analysis of Irf6 ablation in periderm and neural crest lineages. This work found that loss of Irf6 in periderm recapitulates a mild Irf6 null phenotype, suggesting that Irf6-mediated signaling in periderm plays a crucial role in regulating embryonic development. Further, conditional ablation of Irf6 in neural crest cells resulted in an anterior neural tube defect of variable penetrance. The generation of this conditional Irf6 allele allows for new insights into craniofacial development and new exploration into the post-natal role of Irf6.

developmental biology↗

bioRxiv2023

dact1/2 modifies noncanonical Wnt signaling and calpain 8 expression to regulate convergent extension and craniofacial development

Wnt signaling plays crucial roles in embryonic patterning including the regulation of convergent extension during gastrulation, the establishment of the dorsal axis, and later, craniofacial morphogenesis. Further, Wnt signaling is a crucial regulator of craniofacial morphogenesis. The adapter proteins Dact1 and Dact2 modulate the Wnt signaling pathway through binding to Disheveled. However, the distinct relative functions of Dact1 and Dact2 during embryogenesis remain unclear. We found that dact1 and dact2 genes have dynamic spatiotemporal expression domains that are reciprocal to one another suggesting distinct functions during zebrafish embryogenesis. Both dact1 and dact2 contribute to axis extension, with compound mutants exhibiting a similar convergent extension defect and craniofacial phenotype to the wnt11f2 mutant. Utilizing single-cell RNAseq and an established noncanonical Wnt pathway mutant with a shortened axis (gpc4), we identified dact1/2 specific roles during early development. Comparative whole transcriptome analysis between wildtype and gpc4 and wildtype and dact1/2 compound mutants revealed a novel role for dact1/2 in regulating the mRNA expression of the classical calpain capn8. Over-expression of capn8 phenocopies dact1/2 craniofacial dysmorphology. These results identify a previously unappreciated role of capn8 and calcium-dependent proteolysis during embryogenesis. Taken together, our findings highlight the distinct and overlapping roles of dact1 and dact2 in embryonic craniofacial development, providing new insights into the multifaceted regulation of Wnt signaling.

developmental 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

Differences in 5'untranslated regions highlight the importance of translational regulation of dosage sensitive genes

BackgroundUntranslated regions (UTRs) are important mediators of post-transcriptional regulation. The length of UTRs and the composition of regulatory elements within them are known to vary substantially across genes, but little is known about the reasons for this variation in humans. Here, we set out to determine whether this variation, specifically in 5UTRs, correlates with gene dosage sensitivity. ResultsWe investigated 5UTR length, the number of alternative transcription start sites, the potential for alternative splicing, the number and type of upstream open reading frames (uORFs) and the propensity of 5UTRs to form secondary structures. We explored how these elements vary by gene tolerance to loss-of-function (LoF; using the LOEUF metric), and in genes where changes in dosage are known to cause disease. We show that LOEUF correlates with 5UTR length and complexity. Genes that are most intolerant to LoF have longer 5UTRs (P<1x10-15), greater TSS diversity (P<1x 10-15), and more upstream regulatory elements than their LoF tolerant counterparts. We show that these differences are evident in disease gene-sets, but not in recessive developmental disorder genes where LoF of a single allele is tolerated. ConclusionsOur results confirm the importance of post-transcriptional regulation through 5UTRs in tight regulation of mRNA and protein levels, particularly for genes where changes in dosage are deleterious and lead to disease. Finally, to support gene-based investigation we release a web-based browser tool, VuTR (https://vutr.rarediseasegenomics.org/), that supports exploration of the composition of individual 5UTRs and the impact of genetic variation within them.

genomics↗

bioRxiv2023

Dominance is common in mammals and is associated with trans-acting gene expression and alternative splicing

BackgroundDominance and other non-additive genetic effects arise from the interaction between alleles, and historically these phenomena played a major role in quantitative genetics. However, today most genome-wide association studies (GWAS) assume alleles act additively. MethodsWe systematically investigated both dominance - here representing any non-additive effect - and additivity across 574 physiological and gene expression traits in three mammalian models: a Pig F2 Intercross, a Rat Heterogeneous Stock and a Mouse Heterogeneous Stock. ResultsIn all species, and across all physiological traits, dominance accounts for about one quarter of the heritable variance. Hematological and immunological traits exhibit the highest dominance variance, possibly reflecting balancing selection in response to pathogens. Although most quantitative trait loci (QTLs) are detectable assuming additivity, we identified 154, 64 and 62 novel dominance QTLs in pigs, rats and mice respectively, that were undetectable as additive QTLs. Similarly, even though most cis-acting eQTLs are additive, we observed a large fraction of dominance variance in gene expression, and trans-acting eQTLs are enriched for dominance. Genes causal for dominance physiological QTLs are less likely to be physically linked to their QTLs but instead act via trans-acting dominance eQTLs. In addition, in HS rat transcriptomes, thousands of eQTLs associate with alternate transcripts and exhibit complex additive and dominant architectures, suggesting a mechanism for dominance. ConclusionsAlthough heritability is predominantly additive, many mammalian genetic effects are dominant and likely arise through distinct mechanisms. It is therefore advantageous to consider both additive and dominance effects in GWAS to improve power and uncover causality.

genetics↗

bioRxiv2022

Dynamic Interrogation of Stochastic Transcriptome Trajectories Using Disease Associated Genes Reveals Distinct Origins of Neurological and Neuropsychiatric Disorders

1The advent of open access to genomic data offers new opportunities to revisit old clinical debates while approaching them from a different angle. We examine anew the question of whether psychiatric and neurological disorders are different from each other by assessing the pool of genes associated with disorders that are understood as psychiatric or as neurological. We do so in the context of transcriptome data tracked as human embryonic stem cells differentiate and become neurons. Building upon probabilistic layers of increasing complexity, we describe the dynamics and stochastic trajectories of the full transcriptome and the embedded genes associated with psychiatric and/or neurological disorders. From marginal distributions of a genes expression across hundreds of cells, to joint interactions taken globally to determine degree of pairwise dependency, to networks derived from probabilistic graphs along maximal spanning trees, we have discovered two fundamentally different classes of genes underlying these disorders and differentiating them. One class of genes boasts higher variability in expression and lower dependencies ("active genes"); the other has lower variability and higher dependencies ("lazy genes"). They give rise to different network architectures and different transitional states. Active genes have large hubs and a fragile topology, whereas lazy genes show more distributed code during the maturation toward neuronal state. Lazy genes boost differentiation between psychiatric and neurological disorders also at the level of tissue across the brain, spinal cord, and glands. These genes, with their low variability and asynchronous ON/OFF states that have been treated as gross data and excluded from traditional analyses, are helping us settle this old argument at more than one level of inquiry. 2 Manuscript Contribution to the FieldThere is an ongoing debate on whether psychiatric disorders are fundamentally different from neurological disorders. We examine this question anew in the context of transcriptome data tracked as human embryonic stem cells differentiate and become neurons. Building upon probabilistic layers of increasing complexity, we describe the dynamics and stochastic trajectories of the full transcriptome and the embedded genes associated with psychiatric and/or neurological disorders. Two fundamentally different types of genes emerge: "lazy genes" with low, odd, and asynchronous variability patterns in expression that would have been, under traditional approaches, considered superfluous gross data, and "active genes" likely included under traditional computational techniques. They give rise to different network architectures and different transitional dynamic states. Active genes have large hubs and a fragile topology, whereas lazy genes show more distributed code during the maturation toward neuronal state. Under these new wholistic approach, the methods reveal that the lazy genes play a fundamental role in differentiating psychiatric from neurological disorders across more than one level of analysis. Including these genes in future interrogation of transcriptome data may open new lines of inquiry across brain genomics in general.

genomics↗

bioRxiv2022

Sensing Echoes: Temporal misalignment as the Earliest Marker of Neurodevelopmental Derail

Neurodevelopmental disorders are on the rise worldwide, with diagnoses that detect derailment from typical milestones by 3-4.5 years of age. By then, the circuitry in the brain has already reached some level of maturation that inevitably takes neurodevelopment through a different course. There is a critical need then to develop analytical methods that detect problems much earlier and identify targets for treatment. We integrate data from multiple sources, including neonatal auditory brainstem responses (ABR), clinical criteria detecting autism years later in those neonates, and similar ABR information for young infants and children who also received a diagnosis of autism spectrum disorders, to produce the earliest known digital screening biomarker to flag neurodevelopmental derailment in neonates. This work also defines concrete targets for treatment and offers a new statistical approach to aid in guiding a personalized course of maturation in line with the highly nonlinear, accelerated neurodevelopmental rates of change in early infancy. Significance StatementAutism is currently detected on average after 4.5 years of age, based on differences in social interactions. Yet basic building blocks that develop to scaffold social interactions are present at birth and quantifiable at clinics. Auditory Brainstem Response tests, routinely given to neonates, infants, and young children, contain information about delays in signal transmission important for sensory integration. Although currently discarded as gross data under traditional statistical approaches, new analytics reveal unambiguous differences in ABR signals fluctuations between typically developing neonates and those who received an autism diagnosis. With very little effort and cost, these new analytics could be added to the clinical routine testing of neonates to create a universal screening tool for neurodevelopmental derailment and prodrome of autism.

neuroscience↗

bioRxiv2022

Reduced synaptic activity and dysregulated extracellular matrix pathways are common phenotypes in midbrain neurons derived from sporadic and mutation-associated Parkinson's disease patients

Several mutations that cause Parkinsons disease (PD) have been identified over the past decade. These account for 15-25% of PD cases; the rest of the cases are considered sporadic. Currently, it is accepted that PD is not a single monolithic disease but rather a constellation of diseases with some common phenotypes. While rodent models exist for some of the PD-causing mutations, research on the sporadic forms of PD is lagging due to a lack of cellular models. In our study, we differentiated PD patient-derived dopaminergic (DA) neurons from induced pluripotent stem cells (iPSCs) of several PD-causing mutations as well as from sporadic PD patients. Strikingly, we observed a common neurophysiological phenotype: Neurons derived from PD patients had a severe reduction in the rate of synaptic currents compared to those derived from healthy controls. While the relationship between mutations in genes such as the SNCA and LRRK2 and a reduction in synaptic transmission has been investigated before, here we show evidence that the pathogenesis of the synapses in neurons is a general phenotype in PD. Analysis of RNA sequencing results displayed changes in gene expression in different synaptic mechanisms as well as other affected pathways such as extracellular matrix-related pathways. Some of these dysregulated pathways are common to all PD patients (monogenic or idiopathic). Our data, therefore, shows changes that are central and convergent to PD and suggests a strong involvement of the tetra-partite synapse in PD pathophysiology.

neuroscience↗

bioRxiv2021

CLIPreg: Constructing translational regulatory networks from CLIP-, Ribo- and RNA-seq

MotivationThe creation and analysis of gene regulatory networks have been the focus of bioinformatic research and underpins much of what is known about gene regulation. However, as a result of a bias in the availability of data-types that are collected, the vast majority of gene regulatory network resources and tools have focused on either transcriptional regulation or protein-protein interactions. This has left other areas of regulation, for instance translational regulation, vastly underrepresented despite them having been shown to play a critical role in both health and disease. ResultsIn order to address this we have developed CLIPreg, a package that integrates RNA, Ribo and CLIP-sequencing data in order to construct translational regulatory networks coordinated by RNA-binding proteins. This is the first tool of its type to be created, allowing for detailed investigation into a previously unseen layer of regulation. Availability and implementationCLIPreg is available at https://github.com/SGDDNB/CLIPreg. Contactowen.rackham@duke-nus.edu.sg or sonia.chothani@u.duke.nus.edu

bioinformatics↗

bioRxiv2021

Molecular dissection of pro-fibrotic signaling identifies the mechanism underlying IL11-driven fibrosis gene translation, reveals non-specific effects of STAT3 and suggests a new mechanism of action for nintedanib

In fibroblasts, TGF{beta}1 stimulates IL11 upregulation that leads to an autocrine loop of IL11-dependent pro-fibrotic protein translation. The signalling pathways downstream of IL11 are contentious and both STAT3 and ERK have been implicated. Here we show that TGF{beta}1- or IL11-induced ERK activation is consistently associated with fibrogenesis whereas STAT3 phosphorylation (pSTAT3) is unrelated to fibroblast activation. Surprisingly, recombinant human IL11, which has been used extensively in mouse experiments to infer STAT3 activity downstream of IL11, non-specifically increases pSTAT3 in Il11ra1 null mouse fibroblasts. Pharmacologic inhibition of STAT3 prevents TGF{beta}1-induced fibrogenesis but this effect was found to reflect fibroblast dysfunction due to severe proteotoxic ER stress. In contrast, inhibition of MEK/ERK prevented fibrosis in the absence of ER stress. TGF{beta}1-stimulated ERK/mTOR/P70RSK-driven protein translation was IL11-dependent and selectivity for pro-fibrotic protein synthesis was ascribed to an EPRS-related mechanism. In TGF{beta}1-stimulated fibroblasts, the anti-fibrotic drug nintedanib caused dose-dependent ER stress, reduced pSTAT/pERK and inhibited pro-fibrotic protein translation, similarly to generic STAT3 inhibitors or ER stressors. Pirfenidone, while anti-fibrotic, had no effect on ER stress whereas anti-IL11 inhibited the ERK/mTOR axis while reducing ER stress. These studies discount a specific role for STAT3 in pro-fibrotic signaling, suggest a novel mechanism of action for nintedanib and prioritise further the IL11 pathway as a therapeutic target for fibrosis.

molecular biology↗

bioRxiv2021

Overturning the paradigm that IL6 signaling drives liver regrowth while shining light on a new therapeutic target for regenerative medicine

It is accepted that IL6 signaling in hepatocytes, mediated via glycoprotein 130 (gp130), is beneficial and that HyperIL6 promotes liver regeneration by activating STAT3. Recently, autocrine IL11 activity, which also signals via gp130 and ERK, was found to be hepatotoxic. Here we examined whether the beneficial effects of HyperIL6 could reflect unappreciated competitive inhibition of IL11 signaling. In hepatocytes, HyperIL6 inhibited N-acetyl-p-aminophenol (APAP)-induced cell death that mimicked inhibition of IL11 signaling and was unrelated to STAT3 phosphorylation. In mice, expression of HyperIL6 reduced liver damage due to IL11 dosing or APAP and promoted hepatic regeneration in a STAT3-independent manner. Following APAP, mice deleted for Il11 were protected from liver failure and exhibited spontaneous regeneration. Despite robustly activating STAT3, HyperIL6 had no beneficial effect in Il11 null mice. These data overturn the premise that IL6 promotes liver regeneration, show STAT3 activation to be redundant and suggest IL11 as a focus for regenerative medicine.

cell biology↗

bioRxiv2020

Similarities and differences between IL11 and IL11RA1 knockout mice for lung fibro-inflammation, fertility and craniosynostosis

Genetic loss of function (LOF) in IL11RA infers IL11 signaling as important for fertility, fibrosis, inflammation and craniosynostosis. The impact of genetic LOF in IL11 has not been characterized. We generated IL11-knockout (Il11-/-) mice, which are born in normal Mendelian ratios, have normal hematological profiles and are protected from bleomycin-induced lung fibro-inflammation. Noticeably, baseline IL6 levels in the lungs of Il11-/- mice are lower than those of wild-type mice and are not induced by bleomycin damage, placing IL11 upstream of IL6. Lung fibroblasts from Il11-/- mice are resistant to pro-fibrotic stimulation and show evidence of reduced autocrine IL11 activity. Il11-/- female mice are infertile. Unlike Il11ra1-/- mice, Il11-/- mice do not have a craniosynostosis-like phenotype and exhibit mildly reduced body weights. These data highlight similarities and differences between LOF in IL11 or IL11RA while establishing further the role of IL11 signaling in fibrosis and stromal inflammation.

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

Fibroblast-specific IL11 signaling is required for lung fibrosis and inflammation

Tissue injury leads to activation of resident stromal, parenchymal and immune cells to initiate reparative processes that, if unresolved, can lead to fibrosis and organ damage. The directionality of effect between fibrosis and inflammation in the lung has been a point of debate for many years. Here, we tested the hypothesis that Interleukin 11 (IL11) signaling in fibroblasts is of primary importance for pulmonary fibrosis and that this event is upstream of lung inflammation. We generated mice with loxP-flanked Il11ra1 alleles and crossed them to a Col1a2-CreERT strain to enable Il11ra1 deletion in adult fibroblasts (Il11ra1-CKO mice). Lung fibroblasts from Il11ra1-CKO mice were selectively deleted for Il11ra1 and refractory to TGF{beta}1 stimulation. In the mouse model of bleomycin-induced lung fibrosis, Il11ra1-CKO mice had markedly reduced pulmonary fibrosis and lesser lung damage, which was accompanied by diminished ERK activation in the stromal compartment. Bleomycin lung injury in Il11ra1-CKO mice was also associated with diminished STAT3 activation in inflammatory cells, fewer pulmonary immune cell infiltrates and almost complete inhibition of NF-kB activation. These data reveal an essential role for IL11 signaling in fibroblasts for lung fibrosis and show that inflammation in the lung can be secondary to stromal activation.

cell biology↗

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↗