Faculty Bibliography

Drug resistance and cancer relapse represent significant therapeutic challenges after chemotherapy or immunotherapy, and a major limiting factor for long-term cancer survival. Netrin-1 was initially identified as a neuronal navigation cue but has more recently emerged as an interesting target for cancer therapy, which is currently clinically investigated. We show here that netrin-1 is an independent prognostic marker for clinical progression of breast and ovary cancers. Cancer stem cells (CSCs)/Tumor initiating cells (TICs) are hypothesized to be involved in clinical progression, tumor relapse and resistance. We found a significant correlation between netrin-1 expression and cancer stem cell (CSC) markers levels. We also show in different mice models of resistance to chemotherapies that netrin-1 interference using a therapeutic netrin-1 blocking antibody alleviates resistance to chemotherapy and triggers an efficient delay in tumor relapse and this effect is associated with CSCs loss. We also demonstrate that netrin-1 interference limits tumor resistance to immune checkpoint inhibitor and provide evidence linking this enhanced anti-tumor efficacy to a decreased recruitment of a subtype of myeloid-derived suppressor cells (MDSCs) called polymorphonuclear (PMN)-MDSCs. We have functionally demonstrated that these immune cells promote CSCs features and, consequently, resistance to anti-cancer treatments. Together, these data support the view of both a direct and indirect contribution of netrin-1 to cancer stemness and we propose that this may lead to therapeutic opportunities by combining conventional chemotherapies and immunotherapies with netrin-1 interfering drugs.

Patients with coronavirus disease 2019 (COVID-19) present increased risk for ischemic cardiovascular complications up to 1 year after infection. Although the systemic inflammatory response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection likely contributes to this increased cardiovascular risk, whether SARS-CoV-2 directly infects the coronary vasculature and attendant atherosclerotic plaques remains unknown. Here we report that SARS-CoV-2 viral RNA is detectable and replicates in coronary lesions taken at autopsy from severe COVID-19 cases. SARS-CoV-2 targeted plaque macrophages and exhibited a stronger tropism for arterial lesions than adjacent perivascular fat, correlating with macrophage infiltration levels. SARS-CoV-2 entry was increased in cholesterol-loaded primary macrophages and dependent, in part, on neuropilin-1. SARS-CoV-2 induced a robust inflammatory response in cultured macrophages and human atherosclerotic vascular explants with secretion of cytokines known to trigger cardiovascular events. Our data establish that SARS-CoV-2 infects coronary vessels, inducing plaque inflammation that could trigger acute cardiovascular complications and increase the long-term cardiovascular risk.

Hypercholesterolemia and vascular inflammation are key interconnected contributors to the pathogenesis of atherosclerosis. How hypercholesterolemia initiates vascular inflammation is poorly understood. Here we show in male mice that hypercholesterolemia-driven endothelial activation, monocyte recruitment and atherosclerotic lesion formation are promoted by a crosstalk between macrophages and endothelial cells mediated by the cholesterol metabolite 27-hydroxycholesterol (27HC). The pro-atherogenic actions of macrophage-derived 27HC require endothelial estrogen receptor alpha (ERα) and disassociation of the cytoplasmic scaffolding protein septin 11 from ERα, leading to extranuclear ERα- and septin 11-dependent activation of NF-κB. Furthermore, pharmacologic inhibition of cyp27a1, which generates 27HC, affords atheroprotection by reducing endothelial activation and monocyte recruitment. These findings demonstrate cell-to-cell communication by 27HC, and identify a major causal linkage between the hypercholesterolemia and vascular inflammation that partner to promote atherosclerosis. Interventions interrupting this linkage may provide the means to blunt vascular inflammation without impairing host defense to combat the risk of atherosclerotic cardiovascular disease that remains despite lipid-lowering therapies.

The development of new immunotherapies to treat the inflammatory mechanisms that sustain atherosclerotic cardiovascular disease (ASCVD) is urgently needed. Herein, we present a path to drug repurposing to identify immunotherapies for ASCVD. The integration of time-of-flight mass cytometry and RNA sequencing identified unique inflammatory signatures in peripheral blood mononuclear cells stimulated with ASCVD plasma. By comparing these inflammatory signatures to large-scale gene expression data from the LINCS L1000 dataset, we identified drugs that could reverse this inflammatory response. Ex vivo screens, using human samples, showed that saracatinib"”a phase 2a-ready SRC and ABL inhibitor"”reversed the inflammatory responses induced by ASCVD plasma. In Apoe ^{−/−} mice, saracatinib reduced atherosclerosis progression by reprogramming reparative macrophages. In a rabbit model of advanced atherosclerosis, saracatinib reduced plaque inflammation measured by [¹⁸F]fluorodeoxyglucose positron emission tomography"“magnetic resonance imaging. Here we show a systems immunology-driven drug repurposing with a preclinical validation strategy to aid the development of cardiovascular immunotherapies.

Genes specifying long non-coding RNAs (lncRNAs) occupy a large fraction of the genomes of complex organisms. The term 'lncRNAs' encompasses RNA polymerase I (Pol I), Pol II and Pol III transcribed RNAs, and RNAs from processed introns. The various functions of lncRNAs and their many isoforms and interleaved relationships with other genes make lncRNA classification and annotation difficult. Most lncRNAs evolve more rapidly than protein-coding sequences, are cell type specific and regulate many aspects of cell differentiation and development and other physiological processes. Many lncRNAs associate with chromatin-modifying complexes, are transcribed from enhancers and nucleate phase separation of nuclear condensates and domains, indicating an intimate link between lncRNA expression and the spatial control of gene expression during development. lncRNAs also have important roles in the cytoplasm and beyond, including in the regulation of translation, metabolism and signalling. lncRNAs often have a modular structure and are rich in repeats, which are increasingly being shown to be relevant to their function. In this Consensus Statement, we address the definition and nomenclature of lncRNAs and their conservation, expression, phenotypic visibility, structure and functions. We also discuss research challenges and provide recommendations to advance the understanding of the roles of lncRNAs in development, cell biology and disease.

AIMS/OBJECTIVE:Acute myocardial infarction rapidly increases blood neutrophils (<2 hours). Release from bone marrow, in response to chemokine elevation, has been considered their source, but chemokine levels peak up to 24 hours after injury, and after neutrophil elevation. This suggests that additional non-chemokine-dependent processes may be involved. Endothelial cell (EC) activation promotes the rapid (<30 minutes) release of extracellular vesicles (EVs), which have emerged as an important means of cell-cell signalling and are thus a potential mechanism for communicating with remote tissues. METHODS AND RESULTS/RESULTS:Here, we show that injury to the myocardium rapidly mobilises neutrophils from the spleen to peripheral blood and induces their transcriptional activation prior to arrival at the injured tissue. Time course analysis of plasma EV composition revealed a rapid and selective increase in EVs bearing VCAM-1. These EVs, which were also enriched for miRNA-126, accumulated preferentially in the spleen where they induced local inflammatory gene and chemokine protein expression, and mobilised splenic-neutrophils to peripheral blood. Using CRISPR/Cas9 genome editing we generated VCAM-1-deficient EC-EVs and showed that its deletion removed the ability of EC-EVs to provoke the mobilisation of neutrophils. Furthermore, inhibition of miRNA-126 in vivo reduced myocardial infarction size in a mouse model. CONCLUSIONS:Our findings show a novel EV-dependent mechanism for the rapid mobilisation of neutrophils to peripheral blood from a splenic reserve and establish a proof of concept for functional manipulation of EV-communications through genetic alteration of parent cells. TRANSLATIONAL PERSPECTIVE/UNASSIGNED:Peripheral blood neutrophils are rapidly elevated following acute myocardial infarction (AMI) and prior to alterations in systemic cytokines. Extracellular vesicles (EVs) are membrane enclosed particles that carry protein and miRNAs and are rapidly liberated from endothelial cells (EC). Here, we show that following AMI EC-derived-EVs (EC-EVs) mediate neutrophil mobilisation from the spleen via EC-EV-VCAM-1 and induce transcriptional activation of neutrophils in the blood to favour miRNA-126-mRNA targets; miRNA-126 antagomir treatment lowers infarct size. EC-EV-VCAM-1 and EC-EV-miRNA-126 are novel mechanisms that mobilise splenic reserve of neutrophils, a previously unidentified source of neutrophils in sterile ischaemic injury.

Correction to: Nature Cardiovascular Research. Published online 8 June 2023. In the version of this article initially published, a protein (pMAPKAPK2) was misspelled in Fig. 1 and Extended Data Fig. 7; a colored box for "AKT" was missing from the second column of regulators in Fig. 5a; Extended Data Fig. 2f was missing a header above the color key; and typographical errors (extraneous citations to refs. 1, 3 and 5) were present in the "Analysis of RNA-seq data from saracatinib-treated tissue" section of Methods. In addition, the Reporting Summary and the legends for Supplementary Figs. 5 and 8 were outdated versions. The errors have been corrected in the HTML and PDF versions of the article.

Long noncoding RNAs (lncRNAs) have emerged as critical regulators of gene expression, yet their contribution to immune regulation in humans remains poorly understood. Here, we report that the primate-specific lncRNA CHROMR is induced by influenza A virus and SARS-CoV-2 infection and coordinates the expression of interferon-stimulated genes (ISGs) that execute antiviral responses. CHROMR depletion in human macrophages reduces histone acetylation at regulatory regions of ISG loci and attenuates ISG expression in response to microbial stimuli. Mechanistically, we show that CHROMR sequesters the interferon regulatory factor (IRF)-2-dependent transcriptional corepressor IRF2BP2, thereby licensing IRF-dependent signaling and transcription of the ISG network. Consequently, CHROMR expression is essential to restrict viral infection of macrophages. Our findings identify CHROMR as a key arbitrator of antiviral innate immune signaling in humans.

Dysregulation of cholesterol homeostasis is associated with many diseases such as cardiovascular disease and cancer. Liver X receptors (LXRs) are major upstream regulators of cholesterol homeostasis and are activated by endogenous cholesterol metabolites such as 27-hydroxycholesterol (27HC). LXRs and various LXR ligands such as 27HC have been described to influence several extra-hepatic biological systems. However, disparate reports of LXR function have emerged, especially with respect to immunology and cancer biology. This would suggest that, similar to steroid nuclear receptors, the LXRs can be selectively modulated by different ligands. Here, we use RNA-sequencing of macrophages and single-cell RNA-sequencing of immune cells from metastasis-bearing murine lungs to provide evidence that LXR satisfies the 2 principles of selective nuclear receptor modulation: (1) different LXR ligands result in overlapping but distinct gene expression profiles within the same cell type, and (2) the same LXR ligands differentially regulate gene expression in a highly context-specific manner, depending on the cell or tissue type. The concept that the LXRs can be selectively modulated provides the foundation for developing precision pharmacology LXR ligands that are tailored to promote those activities that are desirable (proimmune), but at the same time minimizing harmful side effects (such as elevated triglyceride levels).