Publications by authors named "Panagiota Arampatzi"

Article Synopsis
  • Plexus injuries lead to chronic issues like paralysis, sensory loss, and pain, prompting interest in how the dorsal root ganglia (DRG) are affected following such injuries.
  • A study involving 13 patients revealed that in about half, the typical cell structure of DRG was lost replaced by connective tissue, while others maintained their cellular integrity, although those with preserved neurons reported less pain.
  • The findings suggest two distinct patient groups: those with neuronal preservation who might benefit from anti-inflammatory treatments, and those with neuronal loss needing further research for potential regenerative therapies.
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Motoneurons critically depend on precise spatial and temporal control of translation for axon growth and the establishment and maintenance of neuromuscular connections. While defects in local translation have been implicated in the pathogenesis of motoneuron disorders, little is known about the mechanisms regulating axonal protein synthesis. Here, we report that motoneurons derived from Hnrnpr knockout mice show reduced axon growth accompanied by lowered synthesis of cytoskeletal and synaptic components in axons.

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The human adrenal gland is a complex endocrine tissue. Studies on adrenal renewal have been limited to animal models or human foetuses. Enhancing our understanding of adult human adrenal homeostasis is crucial for gaining insights into the pathogenesis of adrenal diseases, such as adrenocortical tumours.

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Adrenocortical carcinoma (ACC) is a rare yet devastating tumour of the adrenal gland with a molecular pathology that remains incompletely understood. To gain novel insights into the cellular landscape of ACC, we generated single-nuclei RNA sequencing (snRNA-seq) data sets from twelve ACC tumour samples and analysed these alongside snRNA-seq data sets from normal adrenal glands (NAGs). We find the ACC tumour microenvironment to be relatively devoid of immune cells compared to NAG tissues, consistent with known high tumour purity values for ACC as an immunologically "cold" tumour.

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Article Synopsis
  • DYT-TOR1A dystonia is a common disorder that causes muscle cramps, but there aren't many treatments available.
  • Researchers created a special mouse model to study how this condition develops after a nerve injury, which made the mice show more dystonia-like movements.
  • The study found that the brain areas affected by injuries in these mice differ from normal mice, indicating that certain brain processes don’t work right in those with DYT-TOR1A dystonia.
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Myelin defects lead to neurological dysfunction in various diseases and in normal aging. Chronic neuroinflammation often contributes to axon-myelin damage in these conditions and can be initiated and/or sustained by perturbed myelinating glia. We have previously shown that distinct mutations result in neurodegeneration that is largely driven by adaptive immune cells.

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Aims: Aging entails profound immunological transformations that can impact myocardial homeostasis and predispose to heart failure. However, preclinical research in the immune-cardiology field is mostly conducted in young healthy animals, which potentially weakens its translational relevance. Herein, we sought to investigate how the aging T-cell compartment associates with changes in myocardial cell biology in aged mice.

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Background: In the past years, several studies investigated how distinct immune cell subsets affects post-myocardial infarction repair. However, whether and how the tissue environment controls these local immune responses has remained poorly understood. We sought to investigate how antigen-specific T-helper cells differentiate under myocardial milieu's influence.

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Article Synopsis
  • Gut-draining mesenteric lymph nodes play a crucial role in shaping intestinal immune responses, with differences in stromal cell composition based on location.
  • The study identifies specific progenitor cells, CD34 stromal cells and fibroblastic reticular cells, that contribute to the rapid expansion of these lymph nodes from postnatal to aged stages.
  • An epigenomic analysis reveals distinct regulatory patterns in non-endothelial stromal cells, particularly highlighting the role of the Irf3 gene in cellular differentiation and function across different lymph node types.
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Background: Ibrutinib improves the treatment of relapsed or refractory mantle cell lymphoma, a mature B cell neoplasm. However, relapses following treatment with this Bruton tyrosine kinase inhibitor occur frequently, and the outcome of affected patients is poor.

Objectives: Single-cell RNA sequencing (scRNA-seq) can track trends in gene expression of mantle cell lymphoma cells across ibrutinib treatment and new therapeutic targets can be defined based on the detected resistance mechanisms.

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The human gastric epithelium forms highly organized gland structures with different subtypes of cells. The carcinogenic bacterium Helicobacter pylori can attach to gastric cells and subsequently translocate its virulence factor CagA, but the possible host cell tropism of H. pylori is currently unknown.

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Aims: Macrophages have a critical and dual role in post-ischaemic cardiac repair, as they can foster both tissue healing and damage. Multiple subsets of tissue resident and monocyte-derived macrophages coexist in the infarcted heart, but their precise identity, temporal dynamics, and the mechanisms regulating their acquisition of discrete states are not fully understood. To address this, we used multi-modal single-cell immune profiling, combined with targeted cell depletion and macrophage fate mapping, to precisely map monocyte/macrophage transitions after experimental myocardial infarction.

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Reinvigoration of exhausted CD8 T (Tex) cells by checkpoint immunotherapy depends on the activation of precursors of exhausted T (Tpex) cells, but the local anatomical context of their maintenance, differentiation, and interplay with other cells is not well understood. Here, we identified transcriptionally distinct Tpex subpopulations, mapped their differentiation trajectories via transitory cellular states toward Tex cells, and localized these cell states to specific splenic niches. Conventional dendritic cells (cDCs) were critical for successful αPD-L1 therapy and were required to mediate viral control.

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Innate lymphoid cells (ILCs) participate in tissue homeostasis, inflammation, and early immunity against infection. It is unclear how ILCs acquire effector function and whether these mechanisms differ between organs. Through multiplexed single-cell mRNA sequencing, we identified cKitCD127TCF-1 early differentiation stages of T-bet ILC1s.

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Aims: Recent studies have revealed that B cells and antibodies can influence inflammation and remodelling following a myocardial infarction (MI) and culminating in heart failure-but the mechanisms underlying these observations remain elusive. We therefore conducted in mice a deep phenotyping of the post-MI B-cell responses in infarcted hearts and mediastinal lymph nodes, which drain the myocardium. Thereby, we sought to dissect the mechanisms controlling B-cell mobilization and activity in situ.

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Aging is a major risk factor for the development of nervous system functional decline, even in the absence of diseases or trauma. The axon-myelin units and synaptic terminals are some of the neural structures most vulnerable to aging-related deterioration, but the underlying mechanisms are poorly understood. In the peripheral nervous system, macrophages-important representatives of the innate immune system-are prominent drivers of structural and functional decline of myelinated fibers and motor endplates during aging.

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Since the approval of ibrutinib for relapsed/refractory mantle cell lymphoma (MCL), the treatment of this rare mature B-cell neoplasm has taken a great leap forward. Despite promising efficacy of the Bruton tyrosine kinase inhibitor, resistance arises inevitably and the underlying mechanisms remain to be elucidated. Here, we aimed to decipher the response of a sensitive MCL cell line treated with ibrutinib using time-resolved single-cell RNA sequencing.

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B cell maturation antigen (BCMA) is a target for various immunotherapies and a biomarker for tumor load in multiple myeloma (MM). We report a case of irreversible BCMA loss in a patient with MM who was enrolled in the KarMMa trial ( NCT03361748 ) and progressed after anti-BCMA CAR T cell therapy. We identified selection of a clone with homozygous deletion of TNFRSF17 (BCMA) as the underlying mechanism of immune escape.

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Article Synopsis
  • The squamous and columnar epithelia are areas in the cervix that can develop cancer, often starting with a process called metaplasia, where one type of cell is replaced by another.
  • Researchers used advanced technology to study the different types of cells in these areas, discovering that they come from different types of stem cells that are controlled by opposite signals from surrounding tissue.
  • In experiments with mice, they found that changes in the tissue can lead to increased growth of certain stem cells, showing how the balance of cells at the transition zone is influenced by different signals in the tissue around them.
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Rationale: After myocardial infarction, neutrophils rapidly and massively infiltrate the heart, where they promote both tissue healing and damage.

Objective: To characterize the dynamics of circulating and cardiac neutrophil diversity after infarction.

Methods And Results: We employed single-cell transcriptomics combined with cell surface epitope detection by sequencing to investigate temporal neutrophil diversity in the blood and heart after murine myocardial infarction.

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Success of DC vaccines relies on the quality of antigen presentation, costimulation, lymph node migration, and the release of IL-12, in case of Th1 priming. Here, we provide evidence for interaction between the injected vaccine DCs with endogenous lymph node-resident DCs for Th1 induction. While migration of the injected DCs was essential for antigen delivery to the lymph node, the injected DCs contributed only partially to Th0 priming and were unable to instruct Th1 generation.

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Single-cell RNA sequencing (scRNA-seq) has highlighted the important role of intercellular heterogeneity in phenotype variability in both health and disease. However, current scRNA-seq approaches provide only a snapshot of gene expression and convey little information on the true temporal dynamics and stochastic nature of transcription. A further key limitation of scRNA-seq analysis is that the RNA profile of each individual cell can be analysed only once.

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The multitasking promyelocytic leukemia (PML) protein was originally recognized as a tumor-suppressive factor, but more recent evidence has implicated PML in tumor cell prosurvival actions and poor patient prognosis in specific cancer settings. Here, we report that inducible PMLIV expression inhibits cell proliferation as well as self-renewal and impairs cell cycle progression of breast cancer cell lines in a reversible manner. Transcriptomic profiling identified a large number of PML-deregulated genes associated with various cell processes.

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Many evolutionarily distant pathogenic organisms have evolved similar survival strategies to evade the immune responses of their hosts. These include antigenic variation, through which an infecting organism prevents clearance by periodically altering the identity of proteins that are visible to the immune system of the host. Antigenic variation requires large reservoirs of immunologically diverse antigen genes, which are often generated through homologous recombination, as well as mechanisms to ensure the expression of one or very few antigens at any given time.

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