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Ellmeier, W.

Publications and source records attributed to Ellmeier, W..

14 recordsLinked to original sources

Candida-Klebsiella interactions rewire fungal morphogenesis to create a host environment favoring pathogen survival with enhanced tissue pathology

Clinically relevant infections commonly develop within polymicrobial environments where interkingdom interactions shape host responses and disease trajectories. Candida albicans and Klebsiella pneumoniae are critical pathogens that can co-exist in the respiratory tract, yet the consequences of their interaction in terms of fungal physiology, pathogenicity and impact on disease outcomes remain poorly understood. Here, we show that K. pneumoniae enhances C. albicans virulence traits suggesting that co-infections could exacerbate lung disease. Mechanistically, bacterial presence induces fungal hyphal morphogenesis via MAPK-CEK signaling, coupled to metabolic rewiring and alterations in cell wall remodeling and septation, resulting in highly elongated hyphae that escape faster from macrophages. At the host level, co-infection reprograms macrophages into a non-canonical state characterized by overlapping pro- and anti-inflammatory modules, integrating type I interferon and IL-10 signaling. This response contributes to tissue damage and facilitates fungal persistence. Our findings reveal that the bacterial-fungal interactions coordinately reprogram pathogen behavior and host immunity, promoting pathogenic synergy and potentially conferring a negative impact on disease outcomes. HIGHLIGHTSCandida-Klebsiella interactions modulate hyphal morphogenesis. Ectopic morphogenesis encompasses septation, cell wall remodeling and carbon metabolism. Candida-Klebsiella co-infections trigger tissue hyperinflammation and compensatory regulation. Candida-Klebsiella co-infection establishes a host environment facilitating microbial dissemination and tissue pathology. Candida-Klebsiella interactions enhance fungal virulence potentially impacting the severity of co-infections

microbiology↗

Targeting histone acetylation enables epigenetic modulation of inflammatory pathways, a novel therapeutic strategy for rheumatoid arthritis

Autoimmune diseases like rheumatoid arthritis (RA) are characterized by a systemic inflammation caused by autoreactive immune cells. Epigenomic modulation of these cells offers a strategy to reprogram pathogenic pathways without altering the genome, potentially restoring immune balance. Epigenetic inhibitors are already utilized in oncology but often exhibit adverse effects due to lack of selectivity and cytotoxic concentrations. Applying these drugs to treat autoimmune diseases necessitates more selective inhibitors and the use of tolerable concentrations. In this study, we screened a library of 25 compounds with varying degrees of target selectivity and different concentrations. Spectral cytometry enabled the analysis of cell-subset distribution and activation, followed by bulk RNA-sequencing for transcriptomic profiling. We could demonstrate cell-subset specific and concentration-dependent immune modulation in PBMCs. Transcriptomic analysis showed that inhibitors of histone acetylation-modulating enzymes significantly altered gene expression, particularly in immune regulation pathways relevant to autoimmune diseases. Comparative analysis between in-vitro treated healthy controls and RA patients demonstrated both shared and selective drug effects, with some inhibitors like Ricolinostat overlapping with established RA drug pathways. Our findings highlight the potential of epigenetic inhibitors, especially those targeting histone acetylation, to modulate immune responses in a target-selective manner. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/632975v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@30f4faorg.highwire.dtl.DTLVardef@23578borg.highwire.dtl.DTLVardef@4890ceorg.highwire.dtl.DTLVardef@1acbb5_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

Time-resolved immune dynamics in rheumatoid arthritis under Methotrexate therapy

Rheumatoid arthritis (RA) is characterized by immune dysregulation, including alterations in peripheral blood mononuclear cell (PBMC) populations and aberrant cytokine signaling. Methotrexate (MTX) is the preferred first-line treatment for RA, yet its precise mechanisms of action remain incompletely understood. This study employed a multi-omics strategy--combining single-cell RNA sequencing (scRNA-seq) and immunophenotyping--to identify key effector peripheral immune cells and their cellular responses in RA patients over 12 weeks of MTX treatment. In our study, MTX was associated with significant immune modulation, including the restoration of naive T and B cells and reductions in T cell memory subsets with these effects detectable as early as three weeks post-treatment. Plasmablast levels also emerged as a potential biomarker for early therapeutic response, reflecting MTXs impact on immune homeostasis. Transcriptional analysis revealed modulation of key pathways, including TNF- signaling, B cell receptor signaling, and T cell receptor-mediated apoptosis. Network analysis identified critical regulatory hubs, such as EGR1, JAK2, and SOCS1, in monocytes and CD4 memory T cells, highlighting these cell types as key mediators of MTXs effects. In conclusion, these findings advance our understanding of MTXs effects on immune cell dynamics at different stages of treatment, showing for the first time the early cellular changes leading to immune modulation in RA. Altogether, our results provide the foundation for further mechanistic investigations into MTX.

genomics↗

Microbial metabolite-guided CAR T cell engineering enhances anti-tumor immunity via epigenetic-metabolic crosstalk

The microbiome is a complex host factor and key determinant of the outcome of antibody-based and cellular immunotherapy. Its postbiotics are a blend of soluble commensal byproducts that are released into the host environment and have been associated with the regulation of immune homeostasis, particularly through impacts on epigenetics and cell signaling. In this study, we show that the postbiotic pentanoate is metabolized to citrate within the TCA cycle via both the acetyl- and succinyl-CoA entry points, a feature uniquely enabled by the chemical structure of the C5 aliphatic chain. We identified ATP-citrate lyase as the crucial factor that redirects pentanoate-derived citrate from the succinyl-CoA route to the nucleus, thereby linking metabolic output and histone acetylation. This epigenetic-metabolic crosstalk mitigated T cell exhaustion and promoted naive-like differentiation in pentanoate-programmed chimeric antigen receptor (CAR) T cells. The predictive and therapeutic potential of pentanoate was corroborated in two independent patient cohorts and three syngeneic models of CAR T adoptive therapy. Our data demonstrate that postbiotics are integrated into mitochondrial metabolism and subsequently incorporated as epigenetic imprints. This bridge between microbial and mammalian interspecies communication can ultimately impact T cell differentiation and efficacy.

immunology↗

HDAC1 acts as tumor suppressor in ALK-positive anaplastic large-cell lymphoma: Implications for HDAC inhibitor therapy

Histone deacetylases (HDACs) play essential roles in T cell development, and several HDAC inhibitors (HDACi) have gained approval for treating peripheral T cell lymphomas. In this study, we investigated the effects of genetic or pharmacological HDAC inhibition on NPM-ALK positive anaplastic large cell lymphoma (ALCL) development to elucidate potential contraindications or indications for the use of HDACi for the treatment of this rare T-cell lymphoma. Short-term systemic pharmacological inhibition of HDACs using the class I-specific HDACi Entinostat in a premalignant ALCL mouse model postponed or even abolished lymphoma development, despite high expression of the NPM-ALK fusion oncogene. To further disentangle the effects of systemic HDAC inhibition from thymocyte intrinsic effects, conditional genetic deletions of highly homologous class I HDAC1 and HDAC2 enzymes were employed. In sharp contrast to the systemic inhibition, T cell-specific deletion of Hdac1 or Hdac2 in the ALCL mouse model significantly accelerated NPM-ALK-driven lymphomagenesis, with Hdac1 loss having a more pronounced effect. Integration of gene expression and chromatin accessibility data revealed that Hdac1 deletion selectively perturbed cell type specific transcriptional programs, crucial for T cell differentiation and signaling. Moreover, multiple oncogenic signaling pathways, including PDGFRB signaling, were highly upregulated. The accelerated lymphomagenesis primarily depended on the catalytic activity of HDAC1, as the expression of a catalytically inactive HDAC1 protein showed similar effects to the complete knockout. Our findings underscore the tumor-suppressive function of class I HDAC1 and HDAC2 in T cells during ALCL development, however systemic pharmacological inhibition of HDACs is still a valid treatment strategy, which could potentially improve current therapeutic outcomes.

cancer biology↗

HDAC1 controls the generation and maintenance of effector-like CD8+ T cells during chronic viral infection

CD8+ T cell exhaustion is a complex process that involves the differentiation of persistently activated CD8+ T cells into functionally distinct cell subsets. Here, we investigated the role of the key epigenetic regulator histone deacetylase 1 (HDAC1) in the differentiation of exhausted T (Tex) cells during chronic viral infection. We uncovered that HDAC1 controls the generation and maintenance of effector-like CX3CR1+ Tex cells in a CD8+ T cell-intrinsic manner. Deletion of HDAC1 led to expansion of an alternative Tex cell subset characterized by high expression of T cell exhaustion markers, and this was accompanied by elevated viremia. HDAC1 knockout altered the chromatin landscape in progenitor Tex cells, abrogated the expression of effector-like signature genes and interfered with cell fate specification toward the CX3CR1+ Tex cell subset. We conclude that HDAC1 is functionally required for controlling viral load during chronic infection by ensuring adequate CX3CR1+ Tex cell subset differentiation. HighlightsO_LIHDAC1 promotes the generation of CX3CR1+ effector-like Tex cell subsets in chronic viral infection in a CD8+ T cell-intrinsic manner. C_LIO_LIDeletion of HDAC1 leads to an increase of a cell subset enriched in exhaustion markers and is accompanied with elevated viremia. C_LIO_LIHDAC1 is required for the maintenance of the CX3CR1+ Tex cell pool. C_LIO_LIHDAC1 deletion alters the chromatin landscape at effector-like signature gene loci in progenitor Tex cells. C_LI

immunology↗

Single-cell profiling uncovers regulatory programs of pathogenic Th2 cells in allergic asthma

Lung pathogenic T helper type 2 (pTh2) cells are important drivers of allergic asthma, but fundamental questions remain regarding their regulation and heterogeneity. The differentiation and effector functions of immune cells are tightly regulated by epigenetic processes. Histone deacetylase 1 (HDAC1) is an important epigenetic regulator of T cells, however, its role in pTh2 cells is yet to be determined. Here we investigate immune regulation in allergic asthma by single-cell RNA sequencing (scRNA-seq) in mice challenged with house dust mite, in the presence and absence of HDAC1 function. Our analyses reveal two distinct subsets of lung pTh2 cells: pathogenic effector Th2 (peTh2) and pathogenic Th2 tissue-resident memory (Th2 Trm) cells. Both pTh2 cell subsets are highly proinflammatory and exhibit distinct transcriptional and phenotypic signatures as compared with other lung Th subsets. Based on our scRNA-seq analysis, we identify conditions to generate pTh2 cells in vitro and confirm that these in vitro generated pTh2 cells have a similar transcriptional profile as lung peTh2 cells. Using our new in vitro model, we demonstrate that the p38 mitogen-activated protein kinase pathway is critical for interleukin-5 (IL-5) and IL-13 expression in pTh2 cells. Our data further underline the importance of HDAC1 in limiting the pathogenicity of lung and in vitro pTh2 cells and in the formation of lung Th2 Trm cells. In summary, we have generated novel insights into pTh2 cell biology and established a new in vitro model for investigating pTh2 cells that will be useful for discovering molecular mechanisms involved in pTh2-mediated allergic asthma.

immunology↗

Targeting the catalytic activity of HDAC1 in T cells protects against experimental autoimmune encephalomyelitis

Histone deacetylases are key epigenetic regulators that control T cell-mediated immunity. A T cell-specific deletion of Hdac1 (HDAC1cKO) protects mice against experimental autoimmune encephalomyelitis (EAE). However, it remains elusive whether inhibition of HDAC1 enzymatic activity, which could be achieved therapeutically by HDAC1 inhibitor treatment, is sufficient to block EAE induction. In order to address this question, we generated a novel mouse strain that expresses catalytically inactive HDAC1 (HDAC1Off) from the Rosa26 locus in HDAC1cKO CD4+ T cells to mimic selective inhibition of HDAC1 enzymatic activity in vivo. Mice expressing wildtype HDAC1 in HDAC1cKO CD4+ T cells (HDAC1On) were generated as corresponding controls. In contrast to HDAC1On mice, HDAC1Off mice did not develop EAE, and this correlated with diminished leukocyte CNS infiltration. HDAC1Off CD4+ T cells in the CNS displayed a severe reduction of IFN{gamma}, IL-17A and TNF proinflammatory cytokine expression, and in vivo activated HDAC1Off CD4+ T cells downregulated gene sets associated with T cell activation, cytokine expression and cell migration. This indicates impaired effector functions of HDAC1Off CD4+ T cells. Taken together, our study demonstrates that the inhibition of the catalytic activity of HDAC1 in T cells is sufficient to achieve a clinical benefit in EAE disease development. This raises the translational perspective of pharmacological HDAC1 inhibition for treating human T cell-mediated autoimmune diseases. HighlightsO_LISuccessful generation of a novel mouse model that expresses enzymatic-inactive HDAC1 to mimic HDAC1 inhibitor treatment in vivo. C_LIO_LIMice expressing enzymatically inactive HDAC1 instead of WT HDAC1 in T cells do not develop EAE and display diminished leukocyte CNS infiltration. C_LIO_LIIn vivo activated CD4+ T cells expressing enzymatic inactive HDAC1 downregulate pathways important for T cell activation, cytokine expression and cell migration. C_LIO_LIDemonstrate the proof-of-principle that targeting the enzymatic activity of HDAC1 is a promising treatment strategy for autoimmune diseases. C_LI

immunology↗

The guanine nucleotide exchange factor Rin-like acts as a gatekeeper for T follicular helper cell differentiation via regulating CD28 signaling

T follicular helper (Tfh) cells are essential for the development of germinal center B cells and high-affinity antibody producing B-cells in human and mice. Here, we identify the guanine nucleotide exchange factor (GEF) Rin-like (Rinl) as a negative regulator of Tfh generation. Loss of Rinl leads to an increase of Tfh in aging, upon in vivo immunization and acute LCMV Armstrong infection in mice, and in human CD4+ T cell in vitro cultures. Further, adoptive transfer experiments using WT and Rinl-KO naive CD4+ T cells unraveled T cell-intrinsic functions of Rinl. Mechanistically, Rinl regulates CD28 internalization and signaling, thereby shaping CD4+ T cell activation and differentiation. Thus, our results identify the GEF Rinl as a negative regulator of global Tfh differentiation in an immunological context and species-independent manner, and furthermore connect Rinl with CD28 internalization and signaling pathways in CD4+ T cells, demonstrating for the first-time the importance of endocytic processes for Tfh differentiation. HighlightsO_LIRinl-KO CD4+ T cells show increased Tfh differentiation in a context independent manner C_LIO_LIThe regulation of Tfh differentiation is T cell-intrinsic C_LIO_LIRinl controls CD28 endocytosis and shapes Tfh-specific CD28 signal transduction C_LIO_LIHuman Tfh differentiation is regulated by Rinl C_LI

immunology↗

Transcriptional control of adipogenesis by PATZ1

White adipose tissues (WAT) play a central role in lipid storage and systemic energy, lipid, and glucose homeostasis. Understanding the intricacies of adipocyte formation could inform therapies for obesity and metabolic disorders. We have identified the POZ/BTB and AT Hook Containing Zinc Finger 1 (PATZ1) protein as an adipogenic transcription factor through an unbiased high-throughput cDNA screen for modulators of adipogenesis. PATZ1 is expressed by both human and mouse adipocyte precursor cells (APC) and adipocytes, and its expression negatively correlates with obesity. In cell models, PATZ1 expression promotes adipogenesis through a mechanism dependent on protein-protein interaction and DNA binding. Adipose-specific ablation of PATZ1 in mice leads to decreased lipid storage and fat mass and protection from diet-induced obesity. Genome-wide PATZ1 DNA binding analyses using ChIP-Seq suggest that PATZ1 facilitates adipogenesis through interactions with transcription factor machinery at the promoter regions of key adipogenic factors and histone modifiers. Global PATZ1 protein interaction studies using immunoprecipitation-mass spectrometry (IP-MS) suggest that General Transcription Factor 2I (GTF2I) binding to PATZ1 forms a repressive complex, and knockdown of GTF2I augments PATZ1 adipogenic function. Collectively these findings identify PATZ1 as a regulator of the adipocyte differentiation programs and advance our understanding of the complex transcriptional mechanisms underlying adipose tissue development and homeostasis.

molecular biology↗

Nuclear receptor corepressor 1 controls regulatory T cell subset differentiation and effector function

FOXP3+ regulatory T cells (Treg cells) are key for immune homeostasis. Here, we reveal that nuclear receptor corepressor 1 (NCOR1) controls naive and effector Treg cell states. Upon NCOR1 deletion in T cells, effector Treg cell frequencies were elevated in mice and in in vitro-generated human Treg cells. NCOR1-deficient Treg cells failed to protect mice from severe weight loss and intestinal inflammation associated with CD4+ T cell transfer colitis, indicating impaired suppressive function. NCOR1 controls transcriptional integrity of Treg cells, since effector gene signatures were already upregulated in naive NCOR1-deficient Treg cells while effector NCOR1-deficient Treg cells failed to repress genes associated with naive Treg cells. Moreover, genes related to cholesterol homeostasis including targets of liver X receptor (LXR) were dysregulated in NCOR1-deficient Treg cells. However, genetic ablation of LXR{beta} in T cells did not revert the effects of NCOR1 deficiency, indicating that NCOR1 controls naive and effector Treg cell subset composition independent from its ability to repress LXR{beta}-induced gene expression. Thus, our study reveals that NCOR1 maintains naive and effector Treg cell states via regulating their transcriptional integrity. We also reveal a critical role for this epigenetic regulator in supporting the suppressive functions of Treg cells in vivo.

immunology↗

24-Nor-ursodeoxycholic acid counteracts TH17/Treg imbalance and ameliorates intestinal inflammation by restricting glutaminolysis in differentiating TH17 cells

Objective24-Nor-ursodeoxycholic acid (NorUDCA) is a novel therapeutic bile acid for treating primary sclerosing cholangitis (PSC), an immune-mediated cholestatic liver disease. Since PSC strongly associates with inflammatory bowel diseases (IBD) driven by TH17/Treg imbalance, we aimed to explore NorUDCAs immunomodulatory potential on intestinal TH17/Treg balance. DesignNorUDCAs impact on TH17/Treg tissue distribution was first assessed in Mdr2-/- mouse model of PSC. We specifically investigated NorUDCAs effect on modulating TH17/Treg balance in a CD4+ T cell driven colitis model induced by adoptive transfer of CD25-CD44lowCD45RBhighCD4+ TNaive cells into Rag2-/- mice, mimicking human IBD. Mechanistic studies were performed using molecular approaches, flow cytometry and metabolic assays in murine TH17 cells in vitro. NorUDCAs signaling effects observed in murine system were further validated in circulating CD4+ T cells from PSC patients with co-existing IBD. ResultsNorUDCA promoted Treg generation in both liver and intestine in the Mdr2-/- model. In the experimental IBD model, NorUDCA attenuated intestinal immunopathology. Mechanistically, NorUDCA demonstrated strong immunomodulatory efficacy in counteracting TH17/Treg imbalance by restricting glutaminolysis in differentiating TH17 cells, thus suppressed -Ketoglutarate-dependent mTORC1 activation, glycolysis and enhanced FOXP3 expression. NorUDCAs impact on mTORC1 signaling was further confirmed in circulating CD4+ T-cells from PSC patients with IBD. ConclusionNorUDCA possesses direct immunometabolic modulatory potency to counteract TH17/Treg imbalance and ameliorate excessive TH17 cell driven intestinal immunopathology. These findings extend future clinical applications of NorUDCA for treatment of TH17 cell-mediated disorders along the gut-liver axis and beyond. Significance of this studyO_ST_ABSWhat is already known on this subject?C_ST_ABSO_LIPSC is an immune-mediated cholestatic liver disease highly associated with IBD where TH17/Treg imbalance drives immunopathogenesis; seeking effective therapeutics covering both liver and intestinal disease in PSC is of high clinical relevance. C_LIO_LIIndependent of anti-cholestatic effects, NorUDCA has recently been shown to possess direct immunomodulatory properties on CD8+ T cell metabolism, lymphoblastogenesis and clonal expansion through targeting mTORC1 signaling. C_LIO_LISince mTORC1 serves as critical metabolic checkpoint orchestrating TH17/Treg axis, inhibiting mTORC1 activity represents a potential treatment avenue counteracting TH17/Treg imbalance under intestinal inflammatory conditions. C_LI What are the new findings?O_LINorUDCA enriches FOXP3+ Treg population in both liver and intestinal tissue in the cholestatic Mdr2-/- mouse model of PSC. C_LIO_LINorUDCA exhibits direct immunomodulatory efficacies in suppressing excess TH17 cell-mediated intestinal immunopathology and promotes FOXP3+ Treg generation in an experimental IBD model. C_LIO_LIMechanistically, NorUDCA counteracts TH17/Treg imbalance by restricting glutaminolysis in differentiating TH17 cells, thus suppresses -Ketoglutarate-dependent mTORC1 activation, glycolysis and enhances FOXP3 expression. C_LIO_LINorUDCAs impact on mTORC1 signaling was further confirmed in circulating CD4+ T cells from patients with PSC and IBD. C_LI How might it impact on clinical practice in the foreseeable future?These findings advance our current understanding of therapeutic potentials of NorUDCA, which might represent a novel therapeutic strategy in the treatment of PSC and concomitant IBD and other TH17-mediated intestinal diseases.

molecular biology↗

24-Nor-Ursodeoxycholic acid reshapes immunometabolism in CD8+ T cells and alleviates hepatic inflammation

Background & Aims24-NorUrsodeoxycholic acid (NorUDCA) is novel therapy for immune-mediated liver diseases such as primary sclerosing cholangitis (PSC) where dysregulated T cells including CD8+ T cells cause liver immunopathology. We hypothesized that NorUDCA may directly modulate CD8+ T cell effector function thus contributing to its therapeutic efficacy independent of anti-cholestatic effects. MethodsNorUDCA effects on CD8+ T cell function in vivo were investigated in a hepatic injury model system induced by excessive CD8+ T cell immune response upon non-cytolytic lymphocytic choriomeningitis virus (LCMV) infection. Mechanistic studies included molecular and biochemical approaches, flow cytometry and metabolic assays in mouse CD8+ T cells in vitro. Mass spectrometry (MS) was used to identify potential targets modulated by NorUDCA in CD8+ T cells. NorUDCA signaling effects observed in murine systems were validated in peripheral T cells from healthy volunteers and PSC patients. ResultsIn vivo NorUDCA ameliorated hepatic injury and systemic inflammation upon LCMV infection. Mechanistically, NorUDCA demonstrated a strong immunomodulatory efficacy in CD8+ T cells affecting lymphoblastogenesis, mTORC1 signaling and glycolysis of CD8+ T cells. With MS, we identified that NorUDCA regulates CD8+ T cells via targeting mTORC1. NorUDCAs impact on mTORC1 signaling was further confirmed in circulating human CD8+ T cells. ConclusionsNorUDCA possesses a yet-unrecognized direct modulatory potency on CD8+ T cells and attenuates excessive CD8+ T cell hepatic immunopathology. These findings may be relevant for treatment of immune-mediated liver diseases such as PSC and beyond.

molecular biology↗

Requirement of DNMT1 to orchestrate epigenomic reprogramming during NPM-ALK driven T cell lymphomagenesis

Malignant transformation depends on genetic and epigenetic events that result in a burst of deregulated gene expression and chromatin changes. To dissect the sequence of events in this process, we used a T cell-specific lymphoma model based on the human oncogenic NPM-ALK translocation. We find that transformation of T cells shifts thymic cell populations to an undifferentiated immunophenotype, which occurs only after a period of latency, accompanied by induction of the MYC-NOTCH1 axis and deregulation of key epigenetic enzymes. We discover aberrant DNA methylation patterns, overlapping with regulatory regions, plus a high degree of epigenetic heterogeneity between individual tumors. In addition, ALK positive tumors show a loss of collaborative methylation patterns of neighboring CpG sites. Notably, deletion of the maintenance DNA methyltransferase DNMT1 completely abrogates lymphomagenesis in this model, despite oncogenic signaling through NPM-ALK, suggesting that faithful maintenance of tumor-specific methylation through DNMT1 is essential for sustained proliferation and tumorigenesis. STATEMENT OF SIGNIFICANCEEpigenetic alterations are causally involved in tumorigenesis. Here we show that induction of a single human oncogene in murine T cells induces specific deregulation of epigenetic enzymes resulting in epigenomic alterations similar to human tumors. Our findings are of broader implication to understand how epigenomic processes are shaped by oncogene induced transformation.

cancer biology↗