Genetic coupling of enhancer activity and connectivity in gene expression control
Gene enhancers often form long-range contacts with promoters,but it remains unclear if the activity of enhancers and their chromosomal contacts are mediated by the same DNA sequences and recruited factors. Here,we study the effects of expression quantitative trait loci (eQTLs) on enhancer activity and promoter contacts in primary monocytes isolated from 34 male individuals. Using eQTL-Capture Hi-C and a Bayesian approach considering both intra- and inter-individual variation,we initially detect 19 eQTLs associated with enhancer-eGene promoter contacts,most of which also associate with enhancer accessibility and activity. Capitalising on these shared effects,we devise a multi-modality Bayesian strategy,identifying 629 “trimodal QTLs” jointly associated with enhancer accessibility,eGene promoter contact,and gene expression. Causal mediation analysis and CRISPR interference reveal causal relationships between these three modalities. Many detected QTLs overlap disease susceptibility loci and influence the predicted binding of myeloid transcription factors,including SPI1,GABPB and STAT3. Additionally,a variant associated with PCK2 promoter contact directly disrupts a CTCF binding motif and impacts promoter insulation from downstream enhancers. Jointly,our findings suggest an inherent genetic coupling of enhancer activity and connectivity in gene expression control relevant to human disease and highlight the regulatory role of genetically determined chromatin boundaries. Here,the authors study the effects of expression quantitative trait loci on enhancer activity and promoter contacts in primary monocytes isolated from male individuals,suggesting an inherent genetic link between the activity of enhancers,their contacts to target gene promoters and gene expression.
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(Jan 2025)
Nature Communications 16
Genetic variation in IL-4 activated tissue resident macrophages determines strain-specific synergistic responses to LPS epigenetically
How macrophages in the tissue environment integrate multiple stimuli depends on the genetic background of the host,but this is still poorly understood. We investigate IL-4 activation of male C57BL/6 and BALB/c strain specific in vivo tissue-resident macrophages (TRMs) from the peritoneal cavity. C57BL/6 TRMs are more transcriptionally responsive to IL-4 stimulation,with induced genes associated with more super enhancers,induced enhancers,and topologically associating domains (TAD) boundaries. IL-4-directed epigenomic remodeling reveals C57BL/6 specific enrichment of NF-κB,IRF,and STAT motifs. Additionally,IL-4-activated C57BL/6 TRMs demonstrate an augmented synergistic response upon in vitro lipopolysaccharide (LPS) exposure,despite naïve BALB/c TRMs displaying a more robust transcriptional response to LPS. Single-cell RNA sequencing (scRNA-seq) analysis of mixed bone marrow chimeras indicates that transcriptional differences and synergy are cell intrinsic within the same tissue environment. Hence,genetic variation alters IL-4-induced cell intrinsic epigenetic reprogramming resulting in strain specific synergistic responses to LPS exposure. Genetic background affects how macrophages integrate multiple stimuli,e.g.,to IL-4 in tissue environments. BALB/c macrophages show different transcriptional and epigenomic remodeling compared to C57BL/6,leading to distinct synergistic LPS responses.
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(Jan 2025)
Nature Communications 16
Longitudinal omics data and preclinical treatment suggest the proteasome inhibitor carfilzomib as therapy for ibrutinib-resistant CLL
Chronic lymphocytic leukemia is a malignant lymphoproliferative disorder for which primary or acquired drug resistance represents a major challenge. To investigate the underlying molecular mechanisms,we generate a mouse model of ibrutinib resistance,in which,after initial treatment response,relapse under therapy occurrs with an aggressive outgrowth of malignant cells,resembling observations in patients. A comparative analysis of exome,transcriptome and proteome of sorted leukemic murine cells during treatment and after relapse suggests alterations in the proteasome activity as a driver of ibrutinib resistance. Preclinical treatment with the irreversible proteasome inhibitor carfilzomib administered upon ibrutinib resistance prolongs survival of mice. Longitudinal proteomic analysis of ibrutinib-resistant patients identifies deregulation in protein post-translational modifications. Additionally,cells from ibrutinib-resistant patients effectively respond to several proteasome inhibitors in co-culture assays. Altogether,our results from orthogonal omics approaches identify proteasome inhibition as potentially attractive treatment for chronic lymphocytic leukemia patients resistant or refractory to ibrutinib. The molecular mechanisms underlying resistance to therapy in Chronic lymphocytic leukemia (CLL) remain to be explored. Here,the authors perform multi-omics analysis in a mouse model of ibrutinib resistance and suggest proteasome inhibition for overcoming it.
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(Jan 2025)
Respiratory Research 26
Neutrophil extracellular traps (NETs) are increased in rheumatoid arthritis-associated interstitial lung disease
BackgroundNeutrophil extracellular trap (NET) formation has been implicated as a pathogenic mechanism in both rheumatoid arthritis (RA) and interstitial lung disease (ILD). However,the role of NETs in RA-associated ILD (RA-ILD) and the mechanisms driving NET formation remain unclear. This study aimed to assess the involvement of NETs in RA-ILD and elucidate the underlying mechanisms.MethodsSingle-cell sequencing was used to identify changes in the quantity and function of neutrophils in the lung tissue of a zymosan A (ZYM)-induced interstitial pneumonia arthritis model. Additionally,nuclear receptor 4A3 (NR4A3) interference was performed in HL-60 cells to assess its impact on NET formation and the transformation of MRC-5 cells into myofibroblasts. The clinical relevance of plasma myeloperoxidase-DNA (MPO-DNA),citrullinated histone 3 (Cit-H3),and cell-free DNA was evaluated in RA-ILD patients with different imaging types via a commercial enzyme-linked immunosorbent assay (ELISA).ResultsIn the ZYM-treated SKG mouse model,which recapitulates key features of RA-ILD,an increased population of neutrophils in the lung tissue was primarily responsible for NET formation. Mechanistically,we found that interference with NR4A3 expression enhanced NET formation in HL-60 cells,which in turn promoted the differentiation of MRC-5 cells into myofibroblasts. Clinically,plasma MPO-DNA levels are elevated in patients with RA-nonspecific interstitial pneumonia (RA-NSIP),whereas Cit-H3 levels are elevated in RA-usual interstitial pneumonia (RA-UIP) patients compared with healthy subjects. ROC curve analysis further revealed that the combination of plasma MPO-DNA,rheumatoid factor (RF),and anti-citrullinated protein (anti-CCP) and the combination of Cit-H3,RF,and anti-CCP were superior diagnostic panels for NSIP and UIP in RA-ILD patients,respectively. Moreover,compared with those from healthy controls,neutrophils from patients with RA-UIP and RA-NSIP demonstrated a significantly increased ability to form NETs and induce the differentiation of MRC-5 cells into myofibroblasts. Specifically,RA-UIP patients exhibited a greater capacity for NET formation and the differentiation of MRC-5 cells into myofibroblasts than did RA-NSIP patients.ConclusionsThese findings suggest that targeting NETs may be a novel therapeutic approach for treating ILD in RA patients.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12931-025-03111-1.
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(Dec 2024)
STAR Protocols 6 1
Protocol for generating human craniofacial cartilage organoids from stem-cell-derived neural crest cells
SummaryHere,we present a protocol to generate craniofacial cartilage organoids from human stem cells via neural crest stem cells (NCSCs). We describe steps for inducing human embryonic stem cells (hESCs) or induced pluripotent stem cells (iPSCs) to form NCSCs using sequential treatments of small molecules and growth factors and isolating NCSCs by magnetic bead sorting. We then detail procedures for defining conditions where NCSCs migrate together and self-organize into craniofacial cartilage organoids. Recapitulating craniofacial chondrogenesis will facilitate craniofacial reconstruction and disease modeling.For complete details on the use and execution of this protocol,please refer to Foltz et al.1 Graphical abstract Highlights•Protocol for inducing hESCs or iPSCs to form neural crest stem cells (NCSCs)•Steps for differentiating NCSCs into craniofacial cartilage organoids•Instructions for preparing appropriate media and conditions for differentiation•Guidance for assessing changes in cell and organoid morphology during differentiation Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics. Here,we present a protocol to generate craniofacial cartilage organoids from human stem cells via neural crest stem cells (NCSCs). We describe steps for inducing human embryonic stem cells (hESCs) or induced pluripotent stem cells (iPSCs) to form NCSCs using sequential treatments of small molecules and growth factors and isolating NCSCs by magnetic bead sorting. We then detail procedures for defining conditions where NCSCs migrate together and self-organize into craniofacial cartilage organoids. Recapitulating craniofacial chondrogenesis will facilitate craniofacial reconstruction and disease modeling.
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(Jan 2025)
Cancers 17 1
A Novel In Vitro Model of the Bone Marrow Microenvironment in Acute Myeloid Leukemia Identifies CD44 and Focal Adhesion Kinase as Therapeutic Targets to Reverse Cell Adhesion-Mediated Drug Resistance
Simple SummaryAcute myeloid leukemia (AML) is a challenging blood cancer to treat,with only about 24% of patients surviving for 5 years after diagnosis. A key challenge is that AML cells stick to normal cells in the bone marrow (BM),and these BM cells protect them from chemotherapy. The aim of this project is to find drugs that disrupt AML cell adherence to BM cells and release them into the blood,where chemotherapy will be more effective. To achieve this,we have created a model of adhesive BM and shown that it mimics the drug resistance seen clinically. We have used the model as a testing platform for drugs that disrupt AML cell adhesion. We have shown that the combined targeting of CD44 and FAK,using anti-CD44 and the clinical-grade FAK inhibitor defactinib,inhibits the adhesion of the most primitive AML cells that are associated with drug resistance and disease relapse. AbstractBackground/Objectives: Acute myeloid leukemia (AML) is an aggressive neoplasm. Although most patients respond to induction therapy,they commonly relapse due to recurrent disease in the bone marrow microenvironment (BMME). So,the disruption of the BMME,releasing tumor cells into the peripheral circulation,has therapeutic potential. Methods: Using both primary donor AML cells and cell lines,we developed an in vitro co-culture model of the AML BMME. We used this model to identify the most effective agent(s) to block AML cell adherence and reverse adhesion-mediated treatment resistance. Results: We identified that anti-CD44 treatment significantly increased the efficacy of cytarabine. However,some AML cells remained adhered,and transcriptional analysis identified focal adhesion kinase (FAK) signaling as a contributing factor; the adhered cells showed elevated FAK phosphorylation that was reduced by the FAK inhibitor,defactinib. Importantly,we demonstrated that anti-CD44 and defactinib were highly synergistic at diminishing the adhesion of the most primitive CD34high AML cells in primary autologous co-cultures. Conclusions: Taken together,we identified anti-CD44 and defactinib as a promising therapeutic combination to release AML cells from the chemoprotective AML BMME. As anti-CD44 is already available as a recombinant humanized monoclonal antibody,the combination of this agent with defactinib could be rapidly tested in AML clinical trials.
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(Dec 2024)
bioRxiv 947
Modulatory Effects of Mdivi-1 on OxLDL-Induced Metabolic Alterations, Inflammatory Responses, and Foam Cell Formation in Human Monocytes
Atherosclerosis,a major contributor to cardiovascular disease,involves lipid accumulation and inflammatory processes in arterial walls,with oxidized low-density lipoprotein (OxLDL) playing a central role. OxLDL is increased during aging and stimulates monocyte transformation into foam cells and induces metabolic reprogramming and pro-inflammatory responses,accelerating atherosclerosis progression and contributing to other age-related diseases. This study investigated the effects of Mdivi-1,a mitochondrial fission inhibitor,and S1QEL,a selective complex I-associated reactive oxygen species (ROS) inhibitor,on OxLDL-induced responses in monocytes. Healthy monocytes isolated from participants were treated with OxLDL,with or without Mdivi-1 or S1QEL,and assessed for metabolic shifts,inflammatory cytokine expression,foam cell formation,and ROS production. OxLDL treatment elevated glycolytic activity (ECAR) and expression of pro-inflammatory cytokines IL1B and CXCL8,promoting foam cell formation and mitochondrial ROS (mtROS) production. Mdivi-1 and S1QEL effectively reduced OxLDL-induced glycolytic reprogramming,inflammatory cytokine levels,and foam cell formation while limiting mtROS. These findings suggest that both Mdivi-1 and S1QEL modulate key monocyte responses to OxLDL,providing insights into potential therapeutic approaches for age-related diseases.
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(Jan 2025)
Nature Communications 16
Targeting chromosomally unstable tumors with a selective KIF18A inhibitor
Chromosome instability is a prevalent vulnerability of cancer cells that has yet to be fully exploited therapeutically. To identify genes uniquely essential to chromosomally unstable cells,we mined the Cancer Dependency Map for genes essential in tumor cells with high levels of copy number aberrations. We identify and validate KIF18A,a mitotic kinesin,as a vulnerability of chromosomally unstable cancer cells. Knockdown of KIF18A leads to mitotic defects and reduction of tumor growth. Screening of a chemical library for inhibitors of KIF18A enzymatic activity identified a hit that was optimized to yield VLS-1272,which is orally bioavailable,potent,ATP non-competitive,microtubule-dependent,and highly selective for KIF18A versus other kinesins. Inhibition of KIF18A’s ATPase activity prevents KIF18A translocation across the mitotic spindle,resulting in chromosome congression defects,mitotic cell accumulation,and cell death. Profiling VLS-1272 across >100 cancer cell lines demonstrates that the specificity towards cancer cells with chromosome instability differentiates KIF18A inhibition from other clinically tested anti-mitotic drugs. Treatment of tumor xenografts with VLS-1272 results in mitotic defects leading to substantial,dose-dependent inhibition of tumor growth. The strong biological rationale,robust preclinical data,and optimized compound properties enable the clinical development of a KIF18A inhibitor in cancers with high chromosomal instability. Chromosomal instability occurs frequently in cancer,making it an attractive therapeutic target. Here,the authors identify KIF18A as a targetable vulnerability of cancer cells with chromosomal instability and target this using VLS-1272,a selective KIF18A inhibitor.
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(Dec 2024)
Frontiers in Immunology 15
Complement activation drives the phagocytosis of necrotic cell debris and resolution of liver injury
Cells die by necrosis due to excessive chemical or thermal stress,leading to plasma membrane rupture,release of intracellular components and severe inflammation. The clearance of necrotic cell debris is crucial for tissue recovery and injury resolution,however,the underlying mechanisms are still poorly understood,especially in vivo. This study examined the role of complement proteins in promoting clearance of necrotic cell debris by leukocytes and their influence on liver regeneration. We found that independently of the type of necrotic liver injury,either acetaminophen (APAP) overdose or thermal injury,complement proteins C1q and (i)C3b were deposited specifically on necrotic lesions via the activation of the classical pathway. Importantly,C3 deficiency led to a significant accumulation of necrotic debris and impairment of liver recovery in mice,which was attributed to decreased phagocytosis of debris by recruited neutrophils in vivo. Monocytes and macrophages also took part in debris clearance,although the necessity of C3 and CD11b was dependent on the specific type of necrotic liver injury. Using human neutrophils,we showed that absence of C3 or C1q caused a reduction in the volume of necrotic debris that is phagocytosed,indicating that complement promotes effective debris uptake in mice and humans. Moreover,internalization of opsonized debris induced the expression of pro-resolving genes in a C3-dependent manner,supporting the notion that debris clearance favors the resolution of inflammation. In summary,complement activation at injury sites is a pivotal event for necrotic debris clearance by phagocytes and determinant for efficient recovery from tissue injury. Graphical Abstract
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(Dec 2024)
Frontiers in Pharmacology 15 8
The endocannabinoid anandamide prevents TH17 programming of activated T lymphocytes while preserving TH1 responses
IntroductionAnandamide (AEA) is an endocannabinoid that has recently been recognized as a regulator of various inflammatory diseases as well as cancer. While AEA was thought to predominantly engage cannabinoid (CB) receptors,recent findings suggest that,given its protective anti-inflammatory role in pathological conditions,anandamide may engage not only CB receptors.MethodsIn this study,we studied the role of exogenous AEA in a mouse AirPouch model of acute inflammation by examining immune cell infiltrates by flow cytometry. Human primary immune cells were used to validate findings towards immune cell activation and migration by flow cytometry and bead-based ELISA.ResultsWe found that AEA decreases the acute infiltration of myeloid cells including granulocytes and monocytes into the inflamed area,but unexpectedly increases the number of T cells at the site of inflammation. This was related to AEA signaling through nuclear receptor subfamily 4A (NR4A) transcription factors rather than CB receptors. Exploring regulatory mechanisms in the human system,we found that AEA broadly inhibits the migratory capacity of immune cells,arguing for blocked emigration of T cells from the inflamed tissue. Taking a closer look at the impact of AEA on T cells revealed that AEA profoundly alters the activation and exhaustion status of CD4+ T and CD8+ T cells,thereby strongly inhibiting TH17 responses,while not altering TH1 differentiation.DiscussionThese data suggest that AEA has the potential to block chronic inflammation without influencing crucial anti-viral and anti-microbial immune defense mechanisms,and may therefore be an attractive molecule to interfere with the establishment of chronic inflammation.
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(Jan 2025)
Nature Immunology 26 1
Antigen experience history directs distinct functional states of CD8+ CAR T cells during the antileukemia response
Although chimeric antigen receptor (CAR) T cells are effective against B-lineage malignancies,post-CAR relapse is common,and efficacy in other tumors is limited. These challenges may be addressed through rational manipulations to control CAR T cell function. Here we examine the impact of cognate T cell antigen experience on subsequent CD8+ CAR T cell activity. Prior antigen encounter resulted in superior effector function against leukemia expressing low target antigen density at the expense of reduced proliferative capacity and susceptibility to dysfunction at limiting CAR doses. Distinctive temporal transcriptomic and epigenetic profiles in naive-derived and memory-derived CAR T cells identified RUNX family transcription factors as potential targets to augment the function of naive-derived CD8+ CAR T cells. RUNX2 overexpression enhanced antitumor efficacy of mouse CAR T cells,dependent on prior cell state,and heightened human CAR T cell functions. Our data demonstrate that prior antigen experience of CAR T cells determines functional attributes and amenability to transcription factor-mediated functional enhancement. Here,Fry and colleagues examine the impact of antigen experience on subsequent CD8+ CAR T cell activity during the antileukemia response and show that RUNX2 overexpression enhances antitumor activity of these cells.
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(Dec 2024)
Frontiers in Immunology 15 3
Antigen–antibody complex density and antibody-induced HLA protein unfolding influence Fc-mediated antibody effector function
Donor-specific antibodies (DSAs) targeting mismatched human leukocyte antigen (HLA) molecules are one of the principal threats to long-term graft survival in solid organ transplantation. However,many patients with long-term circulating DSAs do not manifest rejection responses,suggesting a degree of heterogeneity in their pathogenicity and related functional activity. Immunologic risk stratification of transplant recipients is complicated by challenges intrinsic to defining alloantibody responses that are potentially pathogenic versus those that are not. Thus,a comprehensive understanding of how human alloantibodies target and interact with donor HLA molecules is vital for the development and evaluation of new strategies aimed at reducing antibody-mediated rejection responses. In this study,we employ hydrogen–deuterium exchange–mass spectrometry (HDX–MS),molecular dynamics (MD) simulations,and advanced biochemical and biophysical methodologies to thoroughly characterize a panel of human monoclonal alloantibodies and define the influence of Fc-region biology,antibody binding kinetics,target antigen density,and structural characteristics on their ability to potentiate the forms of immune effector mechanisms that are strongly implicated in transplant rejection. Our findings have significant implications for our understanding of the key biological determinants that underlie the pathogenicity or lack thereof of human alloantibodies.
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