Biology subjects

Weigert, A.

Publications and source records attributed to Weigert, A..

12 recordsLinked to original sources

bioRxiv2026

IL-38 limits alloreactivity through modulating myeloid and T cell activation

Interleukin-38 (IL-38) is a cytokine of the IL-1 cytokine family that promotes the resolution of inflammation. Resolution mechanisms comprise the induction or recovery of immune tolerance that is lacking in various acute and chronic inflammatory pathologies, including Graft-versus-Host Disease (GvHD). The role of IL-38 in the context of immune tolerance, its primary immune cell targets and underlying molecular mechanisms are not defined. In this study, we investigated the impact of IL-38 on human alloreactivity and in a mouse model of acute GvHD. Our data suggests that monocytes differentiating into macrophages are the main cellular target of IL-38. Specifically, IL-38 reduces antigen presentation capacity in differentiating monocytes through an IL-1 family receptor-independent mechanism, which subsequently avoids T-cell activation. In parallel, IL-38 ameliorates inflammation in allogeneic settings in human and murine GvHD models by promoting the expansion of regulatory T-cells. Our findings indicate that IL-38 promotes immune tolerance during alloreactivity by affecting myeloid cells and T-cells.

immunology↗

bioRxiv2025

Ferroptosis governs lymphatic vessel growth and regression

Whether, when, and how lymphatic vessels undergo cell death remains poorly understood. Here we identify ferroptosis as a physiological, cell-intrinsic regulator of the lymphatic endothelial cell survival during development and following injury, in stark contrast to the resilient organotypic blood endothelial cells. The lymphatic susceptibility to ferroptosis stems from tampered cystine/ hydropersulfide metabolism, alongside reduced glutathione availability triggered by an SH3RF3 E3 ligase mediated GPX4 degradation, and enhanced integration of polyunsaturated fatty acid enriched membrane phospholipids. Inducing ferroptosis genetically or pharmacologically elevated lymphatic lipid peroxidation, halted embryonic lymphangiogenesis and prevented post-injury lymphatic overgrowth while simultaneously shaped immune responses. Conversely, ferroptosis inhibition through saturated fatty acid supplementation led to pathological lymphatic hyperplasia. Targeting lymphatic ferroptotic mechanisms holds promise against pathological lymphatic growth in response to injury.

cell biology↗

bioRxiv2025

Immunomodulatory endothelial cells contribute to T cell recruitment and activation through antigen presentation on MHC class II

AimsA subset of endothelial cells referred to as immunomodulatory endothelial cells (IMEC) has been proposed to regulate T cell responses in atherosclerosis, but their phenotype and function remain poorly understood. Here, we characterized the inflammation-induced emergence of IMEC and their crosstalk with T cells. Methods and ResultsAn in vitro model to study IMEC was established and characterized using flow cytometry and proteomics. Single-cell transcriptome data from human atherosclerotic arteries as well as single cell transcriptome and endothelial cell-specific translatome data from a murine atherogenesis model were used to determine pathophysiological relevance. Immunopeptidomics was performed to detect antigen presentation. T cell chemotaxis, adhesion and activation were assessed through flow cytometry and microscopy. IMEC were induced by treating human endothelial cells with interleukin-1{beta}, interferon-{gamma}, and transforming growth factor-{beta}2. These cells expressed lower levels of classical endothelial cell markers but expressed major histocompatibility complex (MHC) class II, proteins involved in antigen processing and presentation (CD83, CD80 and CD86) and pro-inflammatory cytokines as well as chemokines, including CXCL9. An endothelial cell subpopulation with similar immunomodulatory features was identified in a mouse model of accelerated atherogenesis as well as in human atheromas. Conditioned medium from IMEC enhanced the migration of peripheral blood mononuclear cells and induced T cell chemotaxis, the latter being partially inhibited by antagonizing CXCL9. Proteins related to glycosaminoglycan degradation were significantly downregulated in IMEC which was relevant inasmuch as the glycocalyx plays a key role in the establishment of chemokine gradients. Indeed, the accumulation of heparan sulfates in IMEC contributed to the adhesion of T cells. Notably, IMEC that had been exposed to monocyte lysates presented 627 peptide antigens on MHC class II and induced T cell activation. ConclusionOur data demonstrate the role of IMEC as non-professional antigen-presenting cells that potentially contribute to T cell-mediated immune responses in cardiovascular disease. Translational PerspectiveThis study characterizes immunomodulatory endothelial cells (IMEC) as critical mediators of vascular inflammation through their capacity to process and present exogenous antigens and activate T cells. Induced by pro-atherogenic cytokines (IFN-{gamma}, IL-1{beta}, TGF-{beta}2), IMEC upregulate MHC class II and costimulatory molecules, promote leukocyte chemotaxis, and enhance T cell adhesion through surface heparan sulfate. The identification of IMEC-like populations in both murine models and human atherosclerotic plaques indicates a conserved immunological function in atherogenesis. These findings position IMEC as novel, non-professional antigen-presenting cells and potential therapeutic targets to modulate vascular immune responses in atherosclerotic cardiovascular disease.

immunology↗

bioRxiv2025

Who am I? Optimal Tissue for Germline Genetic Testing Post-Stem Cell Transplantation

With advancements in genetic diagnostics and genotype-based therapeutics, the demand for germline genetic testing in post-hematopoietic stem cell transplantation patients is increasing. Due to genetic chimerism, blood samples can no longer be used for germline testing after transplantation. This study aims to identify the most suitable tissue for germline analysis following stem cell transplantation by investigating alternative tissue sources. Buccal swab, eyebrow hair, and nail samples were analyzed for donor-derived DNA using next-generation sequencing and short tandem repeat analysis, with linear regression used for evaluation. Factors such as HLA match, transplantation type, sex, and time after transplantation were also evaluated for their effect on donor-derived DNA share. Buccal swab and nail samples exhibited 25% and 22% higher proportions of donor-derived DNA compared to eyebrow hair follicles, respectively. The median donor DNA share in eyebrow hair follicles was 1% for NGS and 3% for STR. Factors such as matched related donors, higher HLA match, different donor-recipient sex, and longer time post-transplantation correlated with lower donor DNA shares. Eyebrow hair follicles are a promising tissue for accurate germline genetic testing in post-SCT patients. Patient characteristics like donor relatedness, HLA match, sex match, and time after transplantation should be considered.

genetics↗

bioRxiv2024

Inhibition of IAPs induces programmed cell death and inflammatory signaling in patient-derived metastatic breast cancer organoids

Breast cancer (BC) is the most common type of cancer among women worldwide and underlies relapse, disease progression and metastasis. Resistance to chemotherapy and programmed cell death (PCD), including apoptosis, strongly affects therapy success and remains a major challenge. Representative and translational models to understand, manipulate and cultivate advanced BC and to model PCD resistance are therefore urgently required. Smac mimetics are promising compounds to circumvent apoptosis resistance and are able to induce caspase-independent necroptosis, a lytic and inflammatory mode of PCD. Here, we apply primary, patient-derived human mammary organoids (hMOs) to investigate alternative forms of PCD to overcome apoptosis resistance. Using time lapse brightfield with immunofluorescent confocal microscopy, biochemistry and gene expression analysis, we demonstrate that Smac mimetics induce apoptosis in primary hMOs. By mimicking apoptosis resistance via caspase inhibition, hMOs undergo necroptosis, associated with expression and secretion of inflammatory mediators. Inhibition of linear ubiquitination by the LUBAC inhibitor HOIPIN-8 prevents necroptosis, as well as the expression and release of inflammatory mediators in hMOs. Our findings demonstrate that primary hMOs are effective models to model, study and manipulate PCD responses and inflammation in in primary BC organoids and open new therapeutic screening options for chemotherapy-resistant BC.

cancer biology↗

bioRxiv2023

NFAT5-dependent transcriptional stress control of endothelial cells prevents maladaptive remodeling of pulmonary arterioles in the hypoxic lung

AimsChronic hypoxia causes detrimental structural alterations in the lung, which are partially dependent on stress responses of the endothelium. In this context, we revealed that hypoxia-exposed murine lung endothelial cells (MLEC) activate nuclear factor of activated T-cells 5 (NFAT5) - a transcription factor that adjusts the cellular transcriptome to cope with multiple environmental stressors. Here, we studied the functional relevance of NFAT5 for the control of hypoxia-induced transcription in MLEC. Methods and ResultsTargeted ablation of Nfat5 in endothelial cells did not evoke phenotypic abnormalities in normoxia-exposed mice. However, MLEC in Nfat5-deficient mice up-regulated energy- and protein-metabolism-associated gene expression under normobaric hypoxia (10% O2) for seven days as evidenced by microarray- and scRNA-seq-based analyses. Moreover, loss of NFAT5 boosted the expression and release of platelet-derived growth factor B (Pdgfb) - a HIF1-regulated driver of vascular smooth muscle cell (VSMC) growth - in capillary MLEC of hypoxia-exposed mice, which was accompanied by exaggerated coverage of distal pulmonary arterioles by VSMC, increased pulmonary vascular resistance and impaired right ventricular functions. In vitro, knockout of Nfat5 in cultured MLEC stimulated Pdgfb expression and release after exposure to hypoxia and amplified binding of HIF1 in the Pdgfb promoter region. ConclusionCollectively, our study identifies NFAT5 as a protective transcription factor required to rapidly adjust the transcriptome of MLEC to hypoxia. Specifically, NFAT5 restricts HIF1-mediated Pdgfb expression and consequently limits muscularization and resistance of pulmonary arterioles. HighlightsO_LIHypoxia stimulates the transcriptional activity of NFAT5 in MLEC. C_LIO_LILoss of NFAT5 in hypoxia-exposed MLEC results in EC subtype-specific maladaption of growth factor-, energy- and protein-metabolism-associated gene expression. C_LIO_LISpecifically, NFAT5-deficient capillary lung EC unleash HIF1-regulated Pdgfb expression and release, which results in excessive coverage of pulmonary arterioles by VSMC. C_LIO_LINFAT5-dependent control of early stress responses of capillary MLEC is required to limit the increase in pulmonary vascular resistance and impairment of right ventricular functions. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=166 SRC="FIGDIR/small/563022v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@c9be61org.highwire.dtl.DTLVardef@f1d7cforg.highwire.dtl.DTLVardef@18f795forg.highwire.dtl.DTLVardef@695601_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2022

A novel role for cystathionine gamma lyase in the control of p53: impact on endothelial senescence and metabolic reprograming

AimsAdvanced age is unequivocally linked to the development of cardiovascular disease, however, the mechanisms leading to loss of endothelial cell regenerative capacity during aging remain poorly understood. Here we aimed to investigate novel mechanisms involved in endothelial cell senescence, that impact on endothelial cell transcription and the vascular repair response upon injury Methods and resultsRNA sequencing of a unique collection of native endothelial cells from young and aged individuals, showed that aging (20 vs. 80 years) is characterized by p53- mediated reprogramming to promote the expression of senescence-associate genes. Molecular analysis revelead that p53 accumulated and acetylated in the nucleus of aged human endothelial cells to suppress glycolysis. Metabolic flux analysis identified an associated reduction in glucose uptake and ATP availability that inhibited the assembly of the telomerase complex, which was essential for proliferation. Nuclear translocation of p53 in aged endothelial cells was attributed to the loss of the vasoprotective enzyme, cystathionine {gamma}-lyase (CSE), which physically anchored p53 in the cytosol. In mice, loss of endothelial cell CSE activated p53 and arrested vascular repair upon injury, while the AAV9 mediated re-expression of an active CSE mutant retained p53 in the cytosol, maintained endothelial glucose metabolism and proliferation, and prevented endothelial cell senescence. Adenoviral overexpression of CSE in human native aged endothelial cells maintained low p53 activity and re-activated telomerase to revert endothelial cell senescence. ConclusionOur data identified the interaction between CSE and p53 as a promising target to preserve vascular regeneration during aging. Key QuestionTo identify the mechanisms that regulate endothelial cell senescence under native conditions and their impact on vascular repair in aging. Key FindingLack of a physical interaction between CSE and p53 metabolically reprogrammes endothelial cells to reduce telomerase activity and halt endothelial cell regeneration. Take home messageInterventions to increase CSE expression represent a novel therapy against p53-induced endothelial cell cycle arrest and senescense Translational perspectiveEndothelial rejuvenation strategies could serve as promising therapies against age-related cardiovascular diseases. By investigating human native endothelial cells from young and aged individuals, we identified that the age-related nuclear accumulation of p53 reprograms endothelial cell metabolism, regulates telomerase activity and inhibits endothelial cell regeneration. Nuclear localization of p53 resulted from a loss of its interaction with the cysteine catabolizing enzyme cystathionine {gamma}-lyase in the cytoplasm. Enhancing the physical interaction of p53 with CSE by gene therapy could revert endothelial cell senescence and activate endothelial reparative responses.

cell biology↗

bioRxiv2021

Nuclei are mobile processors enabling specialization in a gigantic single-celled syncytium

In multicellular organisms, the specification, coordination, and compartmentalization of cell types enable the formation of complex body plans. However, some eukaryotic protists such as slime molds generate diverse and complex structures while remaining in a multinucleated syncytial state. It is unknown if different regions of these giant syncytial cells have distinct transcriptional responses to environmental encounters, and if nuclei within the cell diversify into heterogeneous states. Here we performed spatial transcriptome analysis of the slime mold Physarum polycephalum in the plasmodium state under different environmental conditions, and used single-nucleus RNA-sequencing to dissect gene expression heterogeneity among nuclei. Our data identifies transcriptome regionality in the organism that associates with proliferation, syncytial substructures, and localized environmental conditions. Further, we find that nuclei are heterogenous in their transcriptional profile, and may process local signals within the plasmodium to coordinate cell growth, metabolism, and reproduction. To understand how nuclei variation within the syncytium compares to heterogeneity in single-nucleated cells, we analyzed states in single Physarum amoebal cells. We observed amoebal cell states at different stages of mitosis and meiosis, and identified cytokinetic features that are specific to nuclei divisions within the syncytium. Notably, we do not find evidence for predefined transcriptomic states in the amoebae that are observed in the syncytium. Our data shows that a single-celled slime mold can control its gene expression in a region-specific manner while lacking cellular compartmentalization, and suggests that nuclei are mobile processors facilitating local specialized functions. More broadly, slime molds offer the extraordinary opportunity to explore how organisms can evolve regulatory mechanisms to divide labor, specialize, balance competition with cooperation, and perform other foundational principles that govern the logic of life.

cell biology↗

bioRxiv2020

Ngn2 induces diverse neuronal lineages from human pluripotency

Human neurons engineered from induced pluripotent stem cells (iPSCs) through Neurogenin 2 (Ngn2) overexpression are widely used to study neuronal differentiation mechanisms and to model neurological diseases. However, the differentiation paths and heterogeneity of emerged neurons have not been fully explored. Here we used single-cell transcriptomics to dissect the cell states that emerge during Ngn2 overexpression across a time course from pluripotency to neuron functional maturation. We find a substantial molecular heterogeneity in the neuron types generated, with at least two populations that express genes associated with neurons of the peripheral nervous system. Neuron heterogeneity is observed across multiple iPSC clones and lines from different individuals. We find that neuron fate acquisition is sensitive to Ngn2 expression level and the duration of Ngn2 forced expression. Our data reveals that Ngn2 dosage can regulate neuron fate acquisition, and that Ngn2-iN heterogeneity can confound results that are sensitive to neuron type.

neuroscience↗

bioRxiv2020

Comparison of induced neurons reveals slower structural and functional maturation in humans than in apes

We generated induced excitatory sensory neurons (iNeurons, iNs) from chimpanzee, bonobo and human stem cells by expressing the transcription factor neurogenin-2 (NGN2). Single cell-RNA sequencing showed that genes involved in dendrite and synapse development are expressed earlier during iNs maturation in the chimpanzee than the human cells. In accordance, during the first two weeks of differentiation, chimpanzee and bonobo iNs showed repetitive action potentials and more spontaneous excitatory activity than human iNs, and extended neurites of higher total length. However, the axons of human iNs were slightly longer at 5 weeks of differentiation. The timing of the establishment of neuronal polarity did not differ between the species. Chimpanzee, bonobo and human neurites eventually reached the same level of structural complexity. Thus, human iNs develop slower than chimpanzee and bonobo iNs and this difference in timing likely depends on functions downstream of NGN2.

evolutionary biology↗

bioRxiv2019

Single-cell genomic atlas of great ape cerebral organoids uncovers human-specific features of brain development

The human brain has changed dramatically since humans diverged from our closest living relatives, chimpanzees and the other great apes1-5. However, the genetic and developmental programs underlying this divergence are not fully understood6-8. Here, we have analyzed stem cell-derived cerebral organoids using single-cell transcriptomics (scRNA-seq) and accessible chromatin profiling (scATAC-seq) to explore gene regulatory changes that are specific to humans. We first analyze cell composition and reconstruct differentiation trajectories over the entire course of human cerebral organoid development from pluripotency, through neuroectoderm and neuroepithelial stages, followed by divergence into neuronal fates within the dorsal and ventral forebrain, midbrain and hindbrain regions. We find that brain region composition varies in organoids from different iPSC lines, yet regional gene expression patterns are largely reproducible across individuals. We then analyze chimpanzee and macaque cerebral organoids and find that human neuronal development proceeds at a delayed pace relative to the other two primates. Through pseudotemporal alignment of differentiation paths, we identify human-specific gene expression resolved to distinct cell states along progenitor to neuron lineages in the cortex. We find that chromatin accessibility is dynamic during cortex development, and identify instances of accessibility divergence between human and chimpanzee that correlate with human-specific gene expression and genetic change. Finally, we map human-specific expression in adult prefrontal cortex using single-nucleus RNA-seq and find developmental differences that persist into adulthood, as well as cell state-specific changes that occur exclusively in the adult brain. Our data provide a temporal cell atlas of great ape forebrain development, and illuminate dynamic gene regulatory features that are unique to humans.

developmental biology↗

bioRxiv2018

Breaking the ladder: Evolution of the ventral nerve cord in Annelida

A median, segmented, annelid nerve cord has repeatedly been compared to the arthropod and vertebrate nerve cords and became the most used textbook representation of the annelid nervous system. Recent phylogenomic analyses, however, challenge the hypothesis that a subepidermal rope-ladder-like ventral nerve cord (VNC) composed of a paired serial chain of ganglia and somata-free connectives represents neither a plesiomorphic nor a typical condition in annelids.\n\nUsing a comparative approach by combining phylogenomic analyses with morphological methods (immunohistochemistry and CLSM, histology and TEM), we compiled a comprehensive dataset to reconstruct the evolution of the annelid VNC. Our phylogenomic analyses generally support previous topologies. However, the so far hard-to-place Apistobranchidae and Psammodrilidae are now incorporated among the basally branching annelids with high support. Based on this topology we reconstruct an intraepidermal VNC as ancestral state in Annelida. Thus, a subepidermal ladder-like nerve cord clearly represents a derived condition.\n\nBased on the presented data, a ladder-like appearance of the ventral nerve cord evolved repeatedly, and independently of the transition from an intraepidermal to a subepidermal cord during annelid evolution. Our investigations thereby question a common origin of the bilaterian median ganglionated VNC and propose an alternative set of neuroanatomical characteristics of the last common ancestor of Annelida or perhaps even Spiralia.

evolutionary biology↗