Biology subjects

Kiss-Toth, E.

Publications and source records attributed to Kiss-Toth, E..

10 recordsLinked to original sources

bioRxiv2026

Fisetin-mediated MYC restoration improves age-associated decline in macrophage function

Immune decline in older adults is associated with increased susceptibility to infection and chronic inflammatory diseases. Macrophages are critical innate immune cells that show reduced capacity for phagocytosis and migration with age. Our previous work shows that reduced levels of MYC and USF1 transcription factors are drivers of macrophage age-related functional decline. Here we show that macrophage-specific Myc overexpression improves macrophage migration and, more importantly, is able to improve physical performance at older age in Drosophila, while lifespan remains unaffected. Treatment of human primary macrophages from older individuals with the geroprotective supplement fisetin reverses the decline in MYC expression and improves phagocytosis of pathogens and cell migration functions towards levels seen in younger individuals. Mechanistically, fisetin acts via MYC, by restoring expression levels of MYC targets in human macrophages that are altered with age. Finally, fisetin feeding in older mice improves motor activity and reduces frailty, as well as restoring primary macrophage function and Myc expression in vitro. These findings reveal that restoration of MYC in macrophage ageing is responsible, at least in part, for improvement in physical performance with age and identify this pathway as a rational target to reverse age-related immune decline. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=185 SRC="FIGDIR/small/731325v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@1ab6731org.highwire.dtl.DTLVardef@3d85dorg.highwire.dtl.DTLVardef@71c2b3org.highwire.dtl.DTLVardef@a59bf3_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

Comprehensive Bulk and Single-Cell RNA Sequencing Uncovers Senescence-Associated Biomarkers in Therapeutic Mesenchymal Stem Cells

BackgroundMesenchymal stem cells (MSCs) hold great promise in cell therapy, but their effectiveness declines with repeated cell divisions due to senescence. Canines, sharing aging characteristics with humans, serve as a valuable model to study this process in a translational context. MethodsIn the present study, we performed an in-depth characterization of senescence in canine MSCs using a combination of morphological, molecular, and transcriptomic analyses. Early (P2) and late-passage (P6) canine MSCs were characterized using a combination of senescence-associated {beta}-galactosidase staining, cell cycle profiling, and both bulk and single-cell RNA sequencing to capture global transcriptional changes. ResultsBy employing a passage-based in vitro approach, the present study demonstrates that late-passage cells (P6) compared to early-passage cells (P2) exhibit hallmark features of senescence, including morphological alterations, elevated SA-{beta}-galactosidase activity, and considerable transcriptional changes. These changes were represented by significant upregulation of established senescence marker genes, alongside potential novel candidates and downregulation of genes associated with cell cycle progression and proliferation. Moreover, single-cell RNA sequencing uncovered heterogeneous distribution of senescent subpopulations, upregulation of SASP-related genes and reduced proliferation markers. ConclusionsOur findings demonstrate that combining classical markers with bulk and single-cell RNA sequencing facilitates senescent cell identification while improving quality control for clinical MSC samples.

cell biology↗

bioRxiv2024

Exploring the role of E. faecalis Enterococcal Polysaccharide Antigen (EPA) and lipoproteins in evasion of phagocytosis

Enterococcus faecalis is an opportunistic pathogen frequently causing nosocomial infections. The virulence of this organism is underpinned by its capacity to evade phagocytosis, allowing dissemination in the host. Immune evasion requires a surface polysaccharide produced by all enterococci, known as the Enterococcal Polysaccharide Antigen (EPA). EPA consists of a cell wall-anchored rhamnose backbone substituted by strain-specific polysaccharides called "decorations", essential for the biological activity of this polymer. However, the structural determinants required for innate immune evasion remain unknown, partly due to a lack of suitable validated assays. Here, we describe a quantitative, in vitro assay to investigate how EPA decorations alter phagocytosis. Using the E. faecalis model strain OG1RF, we demonstrate that a mutant with a deletion of the locus encoding EPA decorations can be used as a platform strain to express heterologous decorations, thereby providing an experimental system to investigate the inhibition of phagocytosis by strain-specific decorations. We show that the aggregation of cells lacking decorations is increasing phagocytosis and that this process does not involve the recognition of lipoproteins by macrophages. Collectively, our work provides novel insights into innate immune evasion by enterococci and paves the way for further studies to explore the structure/function relationship of EPA decorations.

microbiology↗

bioRxiv2024

Reprogramming Human Inflammatory Macrophages in Symptomatic Carotid Stenosis: Potential Mechanisms for Stabilisation of Atherosclerotic Carotid Plaques

BackgroundInflammation is a precursor to atherosclerotic plaque destabilisation, leading to ischaemic events such as stroke. Macrophage phenotypes can be altered by the microenvironment, and certain anti-inflammatory agents may, therefore, stabilise plaques and reduce the risk of recurrent ischaemic events. MethodsThirteen carotid plaques were obtained from stroke/ Transient Ischaemic Attack (TIA) patients undergoing carotid endarterectomy. An immunofluorescence stain was used to identify common macrophage markers (pan macrophage: CD68, pro-inflammatory: CD86, anti-inflammatory: MRC1), and a novel analysis technique was used to measure the prevalence of macrophage phenotypes in carotid plaques in relation to other histological features of instability. An in vitro model of human blood-derived macrophages was also developed to evaluate the effect of statins and glucocorticoids on macrophage-specific markers using RT-qPCR, Western Blot and immunofluorescence stain. The physiological effect of dexamethasone was further evaluated on macrophages and human carotid plaques cultured ex vivo. ResultsThe macrophage population (CD68+) in the carotid plaques was dominated by "double-positive" (CD86+MRC1+) macrophages (67.8%), followed by "M1-like" (CD86+MRC1-) (16.5%), "M2-like" (CD86-MRC1+) (8.7%) and "double-negative" (CD86-MRC1-) (7.0%) macrophages. M1-like macrophages were more prevalent in unstable plaque sections than stable ones (p=0.0022). Exposure to dexamethasone increased macrophage MRC1 gene expression in vitro and ex vivo. Dexamethasone also reduced Oxidised Low-Density Lipoprotein Receptor 1 (OLR1) gene and protein expression, leading to a decreased ox-LDL uptake in foam cell assays. This was, in turn, associated with reduced lipid uptake in macrophages, as shown by Oil Red O staining. ConclusionsHuman macrophages may be "switched" to a less inflammatory phenotype by exposure to clinically relevant concentrations of glucocorticoid, potentially mediated by a reduction in Oxidised LDL uptake. This effect was not observed following macrophage exposure to statins. Glucocorticoids may have a future role in preventing ischaemic events in patients with advanced atherosclerosis. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=77 SRC="FIGDIR/small/598440v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@bb389borg.highwire.dtl.DTLVardef@18151b8org.highwire.dtl.DTLVardef@11c28a1org.highwire.dtl.DTLVardef@1af6acd_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIA high prevalence (68% in this study) of carotid plaque macrophages express both pro-inflammatory (CD86) and anti-inflammatory (MRC1) markers. These may represent a novel macrophage population. C_LIO_LIHuman macrophages may be "reprogrammed" to a less inflammatory phenotype following exposure to glucocorticoids. C_LIO_LIDexamethasone increased MRC1 and decreased OLR1 expression in macrophages derived from human blood samples in vitro and in cells derived from cultured human carotid plaque tissue ex vivo. This was associated with reduced oxLDL uptake and reduced lipid accumulation in the macrophages. C_LIO_LIDexamethasone has the potential to stabilise carotid atherosclerotic plaques in humans. C_LI

cell biology↗

bioRxiv2023

Ageing-related defects in macrophage function are driven by MYC and USF1 transcriptional programmes

Macrophages are central innate immune cells whose function declines with age. The molecular mechanisms underlying age-related immunity changes remain poorly understood, particularly in human macrophages. We report a substantial reduction in phagocytosis, migration and chemotaxis in human monocyte-derived macrophages (MDMs) from older (>50 years) compared with younger (18-30 years) donors, alongside downregulation of transcription factors MYC and USF1 with age. In MDMs from young donors, knockdown of MYC or USF1 decreased phagocytosis and chemotaxis and altered expression of genes associated with these functions, as well as adhesion and extracellular matrix remodelling. A concordant dysregulation of MYC and USF1 target genes was also seen in MDMs from older donors. Furthermore, older age and loss of either MYC or USF1 in MDMs led to an increased cell size, altered morphology and reduced actin content. Together, these results define MYC and USF1 as key drivers of MDM age-related functional decline and identify downstream targets to improve macrophage function in ageing.

immunology↗

bioRxiv2023

Tribbles1 and Cop1 cooperate to protect the host during in vivo mycobacterial infection

Tuberculosis is a major global health problem and is one of the top 10 causes of death worldwide. There is a pressing need for new treatments that circumvent emerging antibiotic resistance. Mycobacterium tuberculosis parasitises macrophages, reprogramming them to establish a niche in which to proliferate, therefore macrophage manipulation is a potential host-directed therapy if druggable molecular targets could be identified. The pseudokinase Tribbles1 (Trib1) regulates multiple innate immune processes and inflammatory profiles making it a potential drug target in infections. Trib1 controls macrophage function, cytokine production and macrophage polarisation. Despite wide-ranging effects on leukocyte biology, data exploring the roles of Tribbles in infection in vivo are limited. Here, we identify that human Tribbles 1 is expressed in monocytes and is upregulated at the transcript level after stimulation with mycobacterial antigen. To investigate the mechanistic roles of Tribbles in the host response to mycobacteria in vivo, we used a zebrafish Mycobacterium marinum (Mm) infection tuberculosis model. Zebrafish Tribbles family members were characterised and shown to have substantial mRNA and protein sequence homology to their human orthologues. trib1 overexpression was host-protective against Mm infection, reducing burden by approximately 50%. Conversely, trib1 knockdown exhibited increased infection. Mechanistically, trib1 overexpression significantly increased the levels of pro-inflammatory factors il-1{beta} and nitric oxide. The host-protective effect of trib1 was found to be dependent on the E3 ubiquitin kinase Cop1. These findings highlight the importance of Trib1 and Cop1 as immune regulators during infection in vivo and suggest that enhancing macrophage TRIB1 levels may provide a tractable therapeutic intervention to improve bacterial infection outcomes in tuberculosis.

immunology↗

bioRxiv2021

TRIB1 regulates tumour growth via controlling tumour-associated macrophage phenotypes and is associated with breast cancer survival and treatment response

Molecular mechanisms that regulate tumour-associated macrophage (TAM) phenotype and function are incompletely understood. Here, we show that the pseudokinase TRIB1 is highly expressed by TAMs in breast cancer and that its expression correlates with response to chemotherapy and patient survival. We used immune-competent murine models of breast cancer to characterise the consequences of altered (reduced or elevated) myeloid Trib1 expression on tumour growth and composition of stromal immune cells. We found that both overexpression and knockout of myeloid Trib1 promote tumour growth, albeit through distinct molecular mechanisms. Myeloid Trib1 deficiency resulted in an early accelearation of tumour growth, paired with a selective reduction in perivascular macrophage numbers in vivo and enhanced oncogenic cytokine expression in vitro. In contrast, elevated levels of Trib1 in myeloid cells led to an increase in mammary tumour volume at late stages, together with a reduction of NOS2 expressing macrophages and an overall reduction of these cells in hypoxic tumour regions. In addition, we show that myeloid Trib1 is a previously unknown, negative regulator of the anti-tumour cytokine IL-15 and that increased expression of myeloid Trib1 leads to reduced IL-15 levels in mammary tumours, with a consequent reduction in the number of T-cells, that are key to anti-tumour immune responses. Together, these results define the different roles of TRIB1 in human breast cancer and provide a mechanistic understanding for the importance of myeloid TRIB1 expression levels in the development of this disease. SignificanceTRIB1 expression is strongly associated with response to chemotherapy in breast cancer patients with aggressive tumours. This protein is also highly expressed by tumour-associated macrophages. Thus, we used myeloid-specific alterations of Trib1 expression in mice (Trib1mKO and Trib1mTg), and characterised consequent changes in the growth rate and tumour microenvironment of mammary tumours. Both Trib1mKO and Trib1mTg enhanced tumour growth, but at different stages of tumour growth and via distinct mechanisms. Trib1mKO significantly increased the expression of oncogenic cytokines, such as IL6, IL10, CCL20, PD-L1, and VEGF. In contrast, Trib1mTg accelerated at the later stage of tumour growth via inhibition of hypoxic TAMs in the TME, as well as by reduced IL-15 expression thus leading to impaired naive and cytotoxic T cell infiltration. These data define TRIB1 as a potential novel marker of therapeutic responses in breast cancer, as well as a key mechanistic regulator of the anti-tumour cytokine, IL-15 in myeloid cells.

cancer biology↗

bioRxiv2019

Genome-wide association and functional analyses identify CASC20 and KIF26B as target loci in heterotopic ossification

Heterotopic ossification (HO) is bone formation that occurs after trauma within tissues that do not normally have the property of ossification, resulting in pain and disability. The genetic architecture of HO remains unclear. In the first genome-wide association studies of this disease, we identify the human-only long non-coding RNA-encoding gene CASC20 as a robust, replicating susceptibility locus for HO and KIF26B as a potential severity locus. We find that both CASC20 and KIF26B are expressed in human bone. Both CASC20 and KIF26B expression is upregulated upon BMP2 induced osteogenic differentiation in primary human mesenchymal stem cells, followed by RUNX2 and OSTERIX upregulation and mineralised nodule formation. A CRISPR-Cas9 mediated knockout of Kif26b inhibits BMP2-induced Runx2, Sp7/Osterix, Col1A1, Alp, and Bglap/Osteocalcin expression in a murine myocyte model of osteogenic trans-differentiation, and prevents mineralised nodule formation. These studies provide the first insights into the heritable biology of common, complex HO.

genetics↗

bioRxiv2019

Myeloid Tribbles 1 induces early atherosclerosis via enhanced foam cell expansion

Macrophages drive atherosclerotic plaque progression and rupture, hence attenuating their atherosclerosis-inducing properties holds promise for reducing coronary heart disease (CHD). Recent studies in mouse models have demonstrated that Tribbles 1 (Trib1) regulates macrophage phenotype and shows that Trib1 deficiency increases plasma cholesterol and triglyceride levels, suggesting that reduced TRIB1 expression mediates the strong genetic association between the TRIB1 locus and increased CHD risk in man. However, we report here that myeloid-specific Trib1 (mTrib1) deficiency reduces early atheroma formation and that mTrib1 transgene expression increases atherogenesis. Mechanistically, mTrib1 increased macrophage lipid accumulation and the expression of a critical receptor (OLR1), promoting oxidized low density lipoprotein uptake and the formation of lipid-laden foam cells. As TRIB1 and OLR1 RNA levels were also strongly correlated in human macrophages, we suggest that a conserved, TRIB1-mediated mechanism drives foam cell formation in atherosclerotic plaque and that inhibiting mTRIB1 could be used therapeutically to reduce CHD.

immunology↗

bioRxiv2018

Neutrophil microvesicles drive atherosclerosis by delivering miR-155 to atheroprone endothelium.

Neutrophils have been implicated in the pathogenesis of atherosclerosis, a lipid-driven disease of arteries, but they are seldom found in atherosclerotic plaques. To resolve this longstanding paradox, we investigated whether neutrophil-derived microvesicles may influence arterial pathophysiology. Clinical and pre-clinical studies revealed that levels of circulating neutrophil microvesicles were enhanced by exposure to a high fat diet, a known risk factor for atherosclerosis. Neutrophil microvesicles accumulated at disease-prone regions of arteries that are exposed to complex flow patterns, and they promoted vascular inflammation and atherosclerosis in a murine model. Using cultured endothelial cells exposed to disturbed flow, it was demonstrated that neutrophil microvesicles promoted inflammatory gene expression by delivering a microRNA (miR-155) that enhanced NF-{kappa}B activation. Similary, neutrophil microvesicles increased miR-155 and enhanced NF-{kappa}B at disease-prone sites of disturbed flow in arteries of mice. We conclude that delivery of microvesicles carrying miR-155 to disease-prone regions of arteries provides a novel mechanism by which neutrophils contribute to vascular inflammation and atherogenesis.

cell biology↗