Biology subjects

Zernecke, A.

Publications and source records attributed to Zernecke, A..

14 recordsLinked to original sources

bioRxiv2026

TREM2 drives accumulation of pro-scarring monocyte-derived macrophages in the infarcted myocardium

Myocardial infarction is a leading cause of death and disability worldwide. Ischemic injury leads to irreversible loss of cardiomyocytes, the contractile cells of the heart, and formation of a fibrotic scar. After infarction, macrophages massively infiltrate the heart and orchestrate the tissue repair process by removing dead cells and modulating fibroblast activation for scar formation. We previously demonstrated that diverse monocyte-derived macrophage populations dynamically accumulate in the heart following myocardial infarction, notably a pro-repair Trem2hi subset. In this study, we leveraged spatial transcriptomics, single-cell RNA-seq, and functional assays to elucidate the role of TREM2 in driving macrophage-mediated cardiac tissue repair post-infarction. We show that Trem2hi macrophages localize in scarring areas of the infarcted myocardium in the vicinity of collagen-producing myofibroblasts. In Trem2-/- mice, cardiac accumulation of monocyte-derived macrophages with a pro-scarring matrisome-associated macrophage signature was reduced. TREM2 deficiency was functionally associated with reduced fibroblast proliferation, accumulation of myofibroblasts, decreased collagen deposition in the infarcted heart, and increased infarct size. In vitro, we show that TREM2 mediates efferocytosis-induced pro-fibrotic gene expression and promotes macrophage ability to induce fibroblast migration. IL-4 priming of bone marrow-derived macrophages further increased the pro-fibrotic response in macrophages, suggesting that IL-4 and efferocytosis act synergistically to drive this phenotype. Altogether, our results show that TREM2 is essential for the accumulation and function of pro-scarring monocyte-derived macrophages in the infarcted myocardium.

immunology↗

bioRxiv2026

Neutrophil terminal programming in the ischemic heart drives fibrosis after myocardial infarction

Following myocardial infarction (MI), the heart undergoes massive neutrophil infiltration characterized by the emergence of distinct subsets, notably a SiglecF+ population that accumulates according to specific temporal dynamics. The mechanisms governing cardiac neutrophil heterogeneity and the subsequent functional impact of this diversity on tissue repair following myocardial infarction remain to be elucidated. Using single-cell RNA-sequencing of neutrophils in the heart and peripheral organs of infarcted mice, we here show that while acquisition of the SiglecF+ state only fully occurs in the ischemic heart tissue, MI primes neutrophils in the periphery to acquire Siglecf and to upregulate receptors for TGF{beta} and GM-CSF that drive acquisition of the SiglecF+ state. Ly6G targeting in vivo shifted cardiac neutrophils towards the SiglecF+ state at day 3 post-MI, induced the emergence of reprogrammed SiglecF+Ly6Glo and Retnlghi neutrophil states at day 5, and was associated with increased fibrosis of the infarct border zone. Mechanistically, Ly6G targeting reshaped the cardiac immune landscape with increased recruitment of pro-fibrotic {gamma}{delta} T cells and monocytes, and SiglecF+ neutrophils exerted direct pro-fibrotic effects on fibroblasts in a co-culture system. Altogether, our results indicate that peripheral neutrophil priming combined with their terminal programming towards a SiglecF+ state in the ischemic heart drives cardiac fibrosis after MI.

physiology↗

bioRxiv2026

Kidney disease reprograms microbiome-host signaling to promote heart failure

BackgroundHeart failure is prevalent in chronic kidney disease (CKD) and linked to chronic inflammation. CKD-typical gut microbiome dysbiosis may stimulate inflammation, as bacterial aromatic metabolites are highly abundant and engage transcriptional programs through the aryl hydrocarbon receptor (AhR). Whether this axis drives cardiac remodeling and is therapeutically targetable remains unknown. MethodsWe used the subtotal nephrectomy model (STNx) and microbiome depletion by oral antibiotics. We investigated cardiac and renal function, AhR activity, metabolite profiles, and immunophenotypes by flow cytometry and transcriptomics. Candidate metabolite indoxyl sulfate (IxS) was tested in experimental HFpEF. In vivo and in vitro AhR inhibition (AhRi) was performed using a clinically tested compound. Mechanistic studies were performed in primary human and murine cardiac fibroblasts and T cells, as well as translational validation using UK Biobank data. ResultsMicrobiome depletion lowered bacterial metabolites and attenuated cardiac fibrosis and diastolic dysfunction in STNx, identifying AhR-driven expansion of interleukin-17A (IL-17A)-producing T helper cells (TH17) as key effector. Plasma IL-17A was stage-dependently elevated in CKD patients, particularly in HFpEF, and associated with all-cause mortality. Bacterial metabolite IxS promoted TH17 polarization and exacerbated cardiac dysfunction in HFpEF. AhRi using a small molecule inhibitor reduced TH17 abundance and attenuated cardiac fibrosis in STNx. Mechanistically, AhR and IL-17A signaling synergistically induced a conserved pro-fibrotic phenotype in human and murine cardiac fibroblasts, and AhR inhibition blocked ECM production in response to CKD patient serum. ConclusionA microbiome-AhR-IL-17A axis drives CKD-associated cardiac fibrosis. AhRi prevents remodeling, highlighting a potential therapeutic avenue to prevent cardiorenal multimorbidity.

immunology↗

bioRxiv2025

Interleukin-17A Mediates Cardiorenal Injury In Oxalate Nephropathy

AimsCardiovascular disease (CVD) is the leading cause of mortality in chronic kidney disease (CKD). While CKD is known to give rise to systemic inflammation, its inciting factors remain poorly defined. Oxalate, long implicated in rare genetic kidney disorders, accumulates with decreased kidney function and has emerged as a driver of inflammation and independent risk factor for CVD. Here, we investigate the immunological mechanisms linking oxalate nephropathy to systemic inflammation, cardiac damage and kidney injury. Methods and ResultsOxalate nephropathy was induced in C57Bl6/N mice via an oxalate-enriched diet. Oxalate induced systemic immune activation, renal fibrosis, and cardiac remodeling, including pulmonary congestion with systolic and diastolic dysfunction. Flow cytometry analysis identified interleukin (IL)-17A as a dominant inflammatory effector, with expansion of Th17 and Th17-like Treg in the kidney, intestine, and spleen. Bulk mRNA sequencing confirmed these findings. Confirming the oxalate-IL-17A relationship, plasma IL-17A was elevated in patients with primary hyperoxaluria. Gut microbiome analysis by 16S amplicon sequencing showed only mild oxalate-induced alterations in mice. However, soluble oxalate directly enhanced Th17 polarization and disrupted mitochondrial respiration in vitro. In vivo, antibody-mediated (clone: 17F3) IL-17A blockade decreased cardiac fibrosis, reduced neutrophil infiltration, and partially restored cardiac function in oxalate-fed mice. ConclusionsOur study identifies oxalate as a systemic immunometabolic stressor and IL-17A as a central mediator of oxalate-induced cardiorenal injury. These findings establish the oxalate-IL-17A axis as a mechanistic link between CKD and CVD and suggest IL-17A inhibition as a potential therapeutic strategy to reduce cardiovascular damage in CKD. Translational PerspectiveThis study advances our understanding of targetable mediators of the cardiovascular risk in chronic kidney disease (CKD). We identify the organic anion oxalate, beyond its traditional role in crystal-induced kidney damage, as a systemic immunometabolic stressor. We demonstrate that oxalate induces IL-17A-mediated inflammation and thereby contributes to maladaptive cardiac remodeling. Therapeutic blockade of IL-17A protects against oxalate-induced cardiorenal injury, highlighting the oxalate-IL-17A axis as a relevant and druggable link between CKD and cardiovascular disease.

immunology↗

bioRxiv2025

Targeting platelet GPVI or GPIIb/IIIa only minimally affect acute inflammation and cardiac repair in experimental permanent myocardial infarction

BackgroundBeyond their role in hemostasis, platelets are recognized as key regulators of inflammatory responses in ischemic diseases, including cardiac ischemia/reperfusion (I/R) injury with key roles of platelet membrane glycoproteins (GP)VI and IIb/IIIa. However, whether platelet-driven thrombo-inflammatory pathways affect acute inflammation and cardiac repair processes in permanent, non-reperfused myocardial infarction (MI) is unknown. MethodsWe targeted GPVI and GPIIb/IIIa in experimental permanent MI in mice. Cardiac, bone marrow, and blood innate immune responses were evaluated by flow cytometry and single-cell RNA-sequencing. Survival and cardiac repair were assessed over the inflammatory and scar formation phase, until day 10 after permanent MI. ResultsPlatelet GPVI immunodepletion by injection of the anti-GPVI antibody JAQ1 did not affect levels of neutrophil or monocyte subsets (Ly6Chi and Ly6Clow) in the bone marrow and blood, and did not alter accumulation of monocytes, macrophage subsets (defined by expression of MHCII and TIM4), or neutrophil subsets (SiglecFhi/low) in the infarcted heart on day 4. GPVI depletion only had a minimal effect on cardiac repair, slightly decreasing interstitial fibrosis in the infarct border zone on day 10. Four days after MI, GPIIb/IIIa inhibition by JON/A-F(ab')2 had no effect on cardiac or systemic innate immune cell levels as measured by flow cytometry and did not affect composition and transcriptomic profile of the cardiac immune infiltrate as revealed by single-cell RNA-sequencing. GPIIb/IIIa inhibition did not improve cardiac remodeling, and was even associated with an increased mortality rate over 10 days post-MI. ConclusionTargeting the GPVI-GPIIb/IIIa axis only had minor effects on post-MI inflammatory responses and cardiac wound healing in permanent myocardial ischemia. Our findings demonstrate that the therapeutic benefits of inhibiting platelet-driven thrombo-inflammation are particularly relevant in the subacute reperfusion phase.

physiology↗

bioRxiv2025

Secondary lymphoid organ endothelial cells prime alloreactive CD4+ T cells to trigger acute graft-versus-host disease

Donor CD4 T cell priming is a pivotal determinant of acute graft-versus-host disease (aGvHD) after allogeneic hematopoietic cell transplantation (allo-HCT). While professional hematopoietic antigen-presenting cells (APCs) have long been implicated in the pathogenesis of aGvHD, the contribution of non-hematopoietic APCs has remained unclear. Here, we show that naive alloreactive CD4 T cells initially localize and activate specifically within secondary lymphoid organs (SLOs) before infiltrating target tissues. Using genetic models to selectively ablate MHC class II on endothelial cells (ECs) or hematopoietic cells, we demonstrate that blood endothelial cells (BECs) in SLOs function as APCs, efficiently processing and presenting antigen to prime donor CD4 T cells. Deletion of MHC class II (MHCII) specifically in ECs substantially attenuates T cell activation and protects mice from lethal aGvHD, whereas selective deletion of MHCII in lymphatic ECs has no effect. Likewise, selective deletion of MHCII in hematopoietic cells also protects mice against aGvHD, suggesting that both cell types contribute to pathogenic allogeneic T cells activation after allo-HCT. Mechanistically, IL-12/IFN{gamma} signaling upregulates MHC class II expression on BECs. These findings identify BECs in SLOs as initiators of alloreactive CD4 T cell responses and highlight a potential target for preventing aGvHD. HighlightsO_LIBlood endothelial cells in secondary lymphoid organs prime naive CD4 T cells to trigger acute GvHD. C_LIO_LIT cell activation occurs exclusively in secondary lymphoid organs before tissue infiltration. C_LIO_LIExpression of MHC class II only on endothelial cells is sufficient to drive lethal GvHD, independent of other antigen presenting cells. C_LIO_LIRegulation of MHC class II expression in blood endothelial cells by IL-12/IFN{gamma} offers the potential for new therapeutic targets and corroborates findings for existing therapeutics. C_LI

immunology↗

bioRxiv2025

Molecular determinants of cardiac lymphatic dysfunction in a chronic pressure-overload model

Cardiac lymphatics have emerged as potential targets in cardiovascular diseases (CVDs). However, we recently reported that despite extensive lymphatic expansion during experimental cardiac pressure-overload, lymphatic drainage remained insufficient. To unravel the cellular and molecular mechanisms underlying lymphatic dysfunction in CVDs, we applied cardiac single-cell (sc) analyses in a murine heart failure model. Transaortic constriction (TAC), in C57BL/6J and BALB/c mice, was used to model chronic pressure-overload-induced cardiac hypertrophy and heart failure, respectively. Cardiac lymphatic (LEC) and blood vascular (BECs) endothelial cells were analyzed by scRNAseq (10XGenomics). Lymphatic targets were validated by immunohistochemistry and wholemount-imaging, and in vitro using human LEC cultures. We identified three distinct cardiac lymphatic subpopulations, capillary (LEC1), precollector (LEC2), and valvular (LEC3) clusters, and several BECs clusters, including venous BEC (vBEC). Chronic pressure-overload led to expansion of lymphatic capillaries and loss of valves in BALB/c, but not C75BL6/J. Analysis of differentially expressed genes (DEG) post-TAC revealed reduction only in BALB/c of lymphatic cell-junction components. In contrast, LEC expression of anchoring filaments, immune cell-adhesion molecules, and chemokines was preserved, or increased, indicating functional lymphatic-mediated immune cell uptake post-TAC. Interestingly, around 35% of DEGs identified in cardiac LECs post-TAC were similarly altered in interleukin (IL)-1{beta}-stimulated human LECs. In conclusion, loss of lymphatic valves and dysregulated lymphatic barrier properties may underly poor drainage capacity during pressure-overload, despite potent lymphangiogenesis and preserved LEC immune attraction. Further studies are needed to address how to restore lymphatic health to accelerate resolution of both inflammation and edema in CVDs.

cell biology↗

bioRxiv2024

Redirecting full-length FLT1 expression towards its soluble isoform promotes postischemic angiogenesis

Vascular endothelial growth factors and their tyrosine kinase receptors are key mediators of vasculogenesis and angiogenesis with FLT1 (VEGFR1) serving as a decoy receptor. A truncated mRNA transcript encoding soluble (s) FLT1 can be generated by premature cleavage and polyadenylation (APA). Although a shortening of transcripts is described in pathological settings, including heart diseases, the functional in vivo impact of FLT1 gene isoform generation and relevance for angiogenesis remain unknown. Here, we show that specific splice site mutations within Flt1 inhibit telescripting and activate APA in vivo to efficiently modulate gene isoform expression, inducing a complete loss of full-length (fl) Flt1 and a switch towards sFlt1 in mice. FLT1 is a high-affinity decoy receptor of VEGF limiting vessel overgrowth. We show that sFLT1 was sufficient for developmental vasculogenesis, whereas flFLT1 controlled ischemia-driven angiogenesis. Our results demonstrate that telescripting is essential in vivo for controlling Flt1 isoform expression and angiogenesis and can be harnessed to improve reparative revascularization. Furthermore, given the widespread abundance of APA signals, our approach may serve as a blueprint for studying telescripting and generating other truncated gene isoforms in vivo.

cell biology↗

bioRxiv2023

TREM2 limits necrotic core formation during atherogenesis by controlling macrophage survival and efferocytosis

Atherosclerosis is a chronic disease of the vascular wall driven by lipid accumulation and inflammation in the intimal layer of arteries [1], [2], and its main complications, myocardial infarction and stroke, are the leading cause of mortality worldwide [3]. Recent studies have identified Triggering receptor expressed on myeloid cells 2 (TREM2), a lipid-sensing receptor regulating several key myeloid cell functions [4], as a highly expressed marker of macrophage foam cells in experimental and human atherosclerosis [5]. However, the function of TREM2 in the development of atherosclerosis is unknown. Here, we show that hematopoietic or global TREM2 deficiency increases necrotic core formation in early experimental atherosclerosis. We further demonstrate that TREM2 is essential for the efferocytosis capacities of macrophages, and to the survival of lipid-laden macrophages, altogether indicating a crucial role of TREM2 in maintaining the balance between foam cell death and their clearance in atherosclerotic lesions, thereby controlling plaque necrosis.

immunology↗

bioRxiv2022

Taxanes act as vascular disrupting agents and increase rate of metastasis when combined with anti-angiogenic therapy

Taxanes are known to have a profound effect on endothelial cells and the vasculature even at low doses. Here, we show that taxanes, rather than being anti-angiogenic, function more as vascular disrupting agents (VDAs), although they exert a different mechanism of vascular permeabilization when compared to traditional VDAs such as combretastatins. In the tumor context, this VDA-effect leads to a rapid vascular collapse and acute hypoxia. Concomitant treatment with anti-VEGF drugs aggravates hypoxia by blocking vasculogenic rescue mechanisms. While this results in a strong growth-suppressing effect on the tumor, it also increases its invasiveness and metastatic potential. We demonstrate that combination of anti-angiogenic drugs with taxanes blocks tumor reperfusion, intensifies intravasation of circulating tumor cells (CTCs) and strongly increases metastasis. Anti-VEGF drugs are commonly applied in combination with cytotoxic drugs including taxanes. Our findings have significant implications for the clinical use of this drug combination.

cancer biology↗

bioRxiv2022

U1 snRNP-dependent suppression of miRNA biogenesis by alternative intronic polyadenylation in melanoma

Activation of intronic polyadenylation signals results in premature cleavage and polyadenylation (PCPA). The majority of mammalian miRNAs are also located within intronic regions of protein-coding genes and are transcriptionally co-expressed with their host genes. Here we show that U1-dependent PCPA by telescripting dysregulates miRNA biogenesis. When U1 is reduced, miR-211 levels are decreased as a direct consequence of activation of a newly identified alternative intronic polyadenylation signal located upstream of miR-211 within its host gene TRPM1. Various melanoma cell lines revealed decreased U1 levels and a shift from full-length to truncated TRPM1 isoforms with concomitant decreased miR-211 expression. Modulation of TRPM1 alternative polyadenylation (APA) by morpholino oligonucleotides inhibits and potentially restores miR-211 expression to endogenous levels. This mechanism of intronic PCPA and its effects on miRNA biogenesis represents a previously unrecognized layer of gene expression regulation suitable for therapeutic modulation. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=88 SRC="FIGDIR/small/479622v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@169c2f1org.highwire.dtl.DTLVardef@7d8f34org.highwire.dtl.DTLVardef@144b9d8org.highwire.dtl.DTLVardef@10523f1_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2020

Integrated scRNA-seq analysis identifies conserved transcriptomic features of mononuclear phagocytes in mouse and human atherosclerosis

RationaleAccumulation of mononuclear phagocytes (monocytes, macrophages and dendritic cells) in the vessel wall is a hallmark of atherosclerosis. Although single-cell RNA-sequencing (scRNA-seq) has shed new light on immune cell transcriptional diversity in atherosclerosis, it is still unknown whether the transcriptional states of mononuclear phagocytes are conserved between mouse and human atherosclerosis. ObjectiveTo integrate and compare macrophage and dendritic cell transcriptomes in mouse and human atherosclerosis. Methods and resultsWe integrated 12 scRNA-seq datasets of immune cells isolated from healthy or atherosclerotic mouse aortas, and scRNA-seq data from 11 patients (n=4 coronary vessels, n=7 carotid endarterectomy specimens) from two independent studies. Integration of mouse data recovered previously described macrophage populations and identified novel subpopulations with discrete transcriptomic signatures within populations of aortic resident (Lyve1), inflammatory (Il1b), as well as foamy (Trem2hi) macrophages. We identified unique transcriptomic features distinguishing aortic intimal resident macrophages from atherosclerosis-associated Trem2hi macrophages. Also, populations of Xcr1+ type 1 classical dendritic cells (cDC1), Cd209a+ cDC2 and mature DCs (Ccr7, Fscn1) were detected. In humans, we uncovered macrophage and dendritic cell populations with gene expression patterns similar to those observed in mice in both vascular beds. In particular, core transcripts of the foamy/Trem2hi signature (TREM2, SPP1, GPNMB, CD9) mapped to a specific population of macrophages in human lesions. Cross-species data integration demonstrated transcriptionally proximal macrophage and dendritic cell populations in mice and humans. ConclusionsWe demonstrate conserved transcriptomics features of macrophages and dendritic cells in atherosclerosis in mice and humans, emphasizing the relevance of mouse models to study mononuclear phagocytes in atherosclerosis.

immunology↗

bioRxiv2020

Single-cell transcriptomic profiling maps monocyte/macrophage transitions after myocardial infarction in mice

RationaleMonocytes and macrophages have a critical and dual role in post-ischemic cardiac repair, as they can foster both tissue healing and damage. To decipher how monocytes/macrophages acquire heterogeneous functional phenotypes in the ischemic myocardium, we profiled the gene expression dynamics at the single-cell level in circulating and cardiac monocytes/macrophages following experimental myocardial infarction (MI) in mice. Methods and resultsUsing time-series single-cell transcriptome and cell surface epitope analysis of blood and cardiac monocytes/macrophages, as well as the integration of publicly available and independently generated single-cell RNA-seq data, we tracked the transitions in circulating and cardiac monocyte/macrophage states from homeostatic conditions up to 11 days after MI in mice. We show that MI induces marked and rapid transitions in the cardiac mononuclear phagocyte population, with almost complete disappearance of tissue resident macrophages 1 day after ischemia, and rapid infiltration of monocytes that locally acquire discrete and time-dependent transcriptional states within 3 to 7 days. Ischemic injury induced a shift of circulating monocytes towards granulocyte-like transcriptional features (Chil3, Lcn2, Prtn3). Trajectory inference analysis indicated that while conversion to Ly6Clow monocytes appears as the default fate of Ly6Chi monocytes in the blood, infiltrated monocytes acquired diverse gene expression signatures in the injured heart, notably transitioning to two main MI-associated macrophage populations characterized by MHCIIhi and Trem2hiIgf1hi gene expression signatures. Minor ischemia-associated macrophage populations with discrete gene expression signature suggesting specialized functions in e.g. iron handling or lipid metabolism were also observed. We further identified putative transcriptional regulators and new cell surface markers of cardiac monocyte/macrophage states. ConclusionsAltogether, our work provides a comprehensive landscape of circulating and cardiac monocyte/macrophage states and their regulators after MI, and will help to further understand their contribution to post-myocardial infarction heart repair.

immunology↗

bioRxiv2019

Time-resolved single-cell transcriptomics uncovers dynamics of cardiac neutrophil diversity in murine myocardial infarction

ObjectiveAfter myocardial infarction, neutrophils rapidly and massively infiltrate the heart, where they can promote both tissue healing and damage. Here, we investigated the dynamics of cardiac neutrophil heterogeneity after infarction.\n\nMethods and resultsWe employed single-cell transcriptomics (scRNA-seq) to investigate temporal neutrophil heterogeneity in the heart after murine myocardial infarction. At day 1, 3, and 5 after infarction, neutrophils could be delineated into six distinct clusters with specific time-dependent patterning and proportions. While the majority of neutrophils at day 1 were characterized by high expression of chemokines (e.g. Cxcl3, Ccl6), and putative activity of transcriptional regulators involved in hypoxic response (Hif1a) and emergency granulopoiesis (Cebpb), two major subsets of Siglecfhi (enriched for e.g. Icam1 and Tnf) and Siglecflow (Slpi, Ifitm1) neutrophils were found at 3 and 5 days. Flow cytometry analysis confirmed the presence of LY6G+SIGLECFhi and LY6G+SIGLECFlow neutrophils in the heart from 3 days after infarction onwards. LY6G+SIGLECFhi neutrophils were absent from the bone marrow, blood and spleen, suggesting local acquisition of surface SIGLECF. Acquisition of the SIGLECFhi state was paralleled by features of neutrophil ageing and activation (ICAM1hiCXCR4hiCD49dhiCD62Llow). scRNA-seq of atherosclerotic aortas revealed two neutrophil subsets with gene expression patterns reminiscent of the major Siglecfhi and Siglecflow cardiac neutrophil subpopulations, revealing that these populations may be present across distinct contexts of cardiovascular inflammation.\n\nConclusionAltogether, our data provide a time-resolved census of neutrophil diversity and gene expression dynamics in the mouse ischemic heart at the single-cell level, and suggests that temporal neutrophil heterogeneity is in part driven by local transition to a SIGLECFhi state.

immunology↗