Tie2-Dependent Mechanisms Promote Leptomeningeal Collateral Remodeling and Reperfusion Following StrokeKaloss, de Jager, Lyles
et albioRxiv (2025)
Abstract: Leptomeningeal collaterals are distal pial arterial anastomotic vessels that provide an alternative route for redistributing cerebral blood flow following arterial obstruction, thereby limiting tissue damage. However, the regulatory mechanisms and strategies to enhance this adaptive response remain under investigation. This study explored the pharmacological effects of Tie2 receptor activation, using the peptide agonist Vasculotide, following permanent middle cerebral artery occlusion (pMCAO). Vasculotide improved collateral growth and remodeling, which correlated with reduced infarct volume, enhanced blood flow, and functional recovery within 24hrs post-pMCAO. In contrast, collateral growth was attenuated in Tie2 and EphA4/Tie2 double knockdown mice, while the loss of EphA4 increased Tie2 and Ang-1 expression and mimicked the positive effects of Vasculotide following stroke. Furthermore, bulk RNA sequencing of meningeal tissue identified key transcriptomic changes, including alterations in AJ-associated transcripts, such as Krt5 , Krt14 , and Col17a1 , in the ipsilateral meninges of both endothelial cell-specific EphA4 knockout and Vasculotide-treated mice. Krt5 expression was found upregulated on meningeal arterial vascular network in injured KO mice, highlighting a potential new mediator of meningeal vascular remodeling. These findings illustrate that EphA4 and Tie2 play opposing roles in collateral remodeling, including the regulation of Krt5. Modulating their activity could potentially enhance the collateral response to stroke.
Interrogating mediators of single-cell transcriptional changes in the acute damaged cerebral cortex: Insights into endothelial-astrocyte interactionsde Jager, Soliman, Theus
Mol Cell Neurosci (2025) 133, 104003
Abstract: Traumatic brain injury (TBI) induces complex cellular and molecular changes, challenging recovery and therapeutic development. Although molecular pathways have been implicated in TBI pathology, the cellular specificity of these mechanisms remains underexplored. Here, we investigate the role of endothelial cell (EC) EphA4, a receptor tyrosine kinase receptor involved in axonal guidance, in modulating cell-specific transcriptomic changes within the damaged cerebral cortex. Utilizing single-cell RNA sequencing (scRNA-seq) in an experimental TBI model, we mapped transcriptional changes across various cell types, with a focus on astrocytes and ECs. Our analysis reveals that EC-specific knockout (KO) of EphA4 triggers significant alterations in astrocyte gene expression and shifts predominate subclusters. We identified six distinct astrocyte clusters (C0-C5) in the damaged cortex including as C0-Mobp/Plp1+; C1-Slc1a3/Clu+; C2-Hbb-bs/Hba-a1/Ndrg2+; C3-GFAP/Lcn2+; C4-Gli3/Mertk+, and C5-Cox8a+. We validate a new Sox9+ cluster expressing Mertk and Gas, which mediates efferocytosis to facilitate apoptotic cell clearance and anti-inflammatory responses. Transcriptomic and CellChat analyses of EC-KO cells highlights upregulation of neuroprotective pathways, including increased amyloid precursor protein (APP) and Gas6. Key pathways predicted to be modulated in astrocytes from EC-KO mice include oxidative phosphorylation and FOXO signaling, mitochondrial dysfunction and ephrin B signaling. Concurrently, metabolic and signaling pathways in endothelial cells-such as ceramide and sphingosine phosphate metabolism and NGF-stimulated transcription-indicate an adaptive response to a metabolically demanding post-injury hypoxic environment. These findings elucidate potential interplay between astrocytic and endothelial responses as well as transcriptional networks underlying cortical tissue damage.Copyright © 2025 Elsevier Inc. All rights reserved.
A novel classification method for LUAD that guides personalized immunotherapy on the basis of the cross-talk of coagulation- and macrophage-related genesLi, Chen, Wei
et alFront Immunol (2025) 16, 1518102
Abstract: The coagulation process and infiltration of macrophages affect the progression and prognosis of lung adenocarcinoma (LUAD) patients. This study was designed to explore novel classification methods that better guide the precise treatment of LUAD patients on the basis of coagulation and macrophages.Weighted gene coexpression network analysis (WGCNA) was applied to identify M2 macrophage-related genes, and TAM marker genes were acquired through the analysis of scRNA-seq data. The MSigDB and KEGG databases were used to obtain coagulation-associated genes. The intersecting genes were defined as coagulation and macrophage-related (COMAR) genes. Unsupervised clustering analysis was used to evaluate distinct COMAR patterns for LUAD patients on the basis of the COMAR genes. The R package "limma" was used to identify differentially expressed genes (DEGs) between COMAR patterns. A prognostic risk score model, which was validated through external data cohorts and clinical samples, was constructed on the basis of the COMAR DEGs.In total, 33 COMAR genes were obtained, and three COMAR LUAD subtypes were identified on the basis of the 33 COMAR genes. There were 341 DEGs identified between the three COMAR subtypes, and 60 prognostic genes were selected for constructing the COMAR risk score model. Finally, 15 prognosis-associated genes (CORO1A, EPHA4, FOXM1, HLF, IFIH1, KYNU, LY6D, MUC16, PPARG, S100A8, SPINK1, SPINK5, SPP1, VSIG4, and XIST) were included in the model, which was efficient and robust in predicting LUAD patient prognosis and clinical outcomes in patients receiving anti-PD-1/PD-L1 immunotherapy.LUAD can be classified into three subtypes according to COMAR genes, which may provide guidance for precise treatment.Copyright © 2025 Li, Chen, Wei, Liu, Zhang, Huang, Wen and Tian.
Cancer stem cells and tumor-associated macrophages as mates in tumor progression: mechanisms of crosstalk and advanced bioinformatic tools to dissect their phenotypes and interactionVerona, Di Bella, Schirano
et alFront Immunol (2025) 16, 1529847
Abstract: Cancer stem cells (CSCs) are a small subset within the tumor mass significantly contributing to cancer progression through dysregulation of various oncogenic pathways, driving tumor growth, chemoresistance and metastasis formation. The aggressive behavior of CSCs is guided by several intracellular signaling pathways such as WNT, NF-kappa-B, NOTCH, Hedgehog, JAK-STAT, PI3K/AKT1/MTOR, TGF/SMAD, PPAR and MAPK kinases, as well as extracellular vesicles such as exosomes, and extracellular signaling molecules such as cytokines, chemokines, pro-angiogenetic and growth factors, which finely regulate CSC phenotype. In this scenario, tumor microenvironment (TME) is a key player in the establishment of a permissive tumor niche, where CSCs engage in intricate communications with diverse immune cells. The "oncogenic" immune cells are mainly represented by B and T lymphocytes, NK cells, and dendritic cells. Among immune cells, macrophages exhibit a more plastic and adaptable phenotype due to their different subpopulations, which are characterized by both immunosuppressive and inflammatory phenotypes. Specifically, tumor-associated macrophages (TAMs) create an immunosuppressive milieu through the production of a plethora of paracrine factors (IL-6, IL-12, TNF-alpha, TGF-beta, CCL1, CCL18) promoting the acquisition by CSCs of a stem-like, invasive and metastatic phenotype. TAMs have demonstrated the ability to communicate with CSCs via direct ligand/receptor (such as CD90/CD11b, LSECtin/BTN3A3, EPHA4/Ephrin) interaction. On the other hand, CSCs exhibited their capacity to influence immune cells, creating a favorable microenvironment for cancer progression. Interestingly, the bidirectional influence of CSCs and TME leads to an epigenetic reprogramming which sustains malignant transformation. Nowadays, the integration of biological and computational data obtained by cutting-edge technologies (single-cell RNA sequencing, spatial transcriptomics, trajectory analysis) has significantly improved the comprehension of the biunivocal multicellular dialogue, providing a comprehensive view of the heterogeneity and dynamics of CSCs, and uncovering alternative mechanisms of immune evasion and therapeutic resistance. Moreover, the combination of biology and computational data will lead to the development of innovative target therapies dampening CSC-TME interaction. Here, we aim to elucidate the most recent insights on CSCs biology and their complex interactions with TME immune cells, specifically TAMs, tracing an exhaustive scenario from the primary tumor to metastasis formation.Copyright © 2025 Verona, Di Bella, Schirano, Manfredi, Angeloro, Bozzari, Todaro, Giannini, Stassi and Veschi.
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Star Staining
