KSKathrin Saar

Kathrin Saar

*This is an algorithmically generated author record based on publicly available information.

Current Organizations / Institutes

The organizations/institutes from the scholar's latest article

Previous Organizations / Institutes

The organizations / institutes from the scholar's other articles in the past ten years


Kathrin Saar has a total of 882 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Top Cited Papers
    Open Access

    Multiomic analyses uncover immunological signatures in acute and chronic coronary syndromes

    by Kami Pekayvaz, Corinna Losert, Viktoria Knottenberg, Christoph Gold, Irene V. van Blokland, Roy Oelen, Hilde E. Groot, Jan Walter Benjamins, Sophia Brambs, Rainer Kaiser, et al.

    Acute and chronic coronary syndromes (ACS and CCS) are leading causes of mortality. Inflammation is considered a key pathogenic driver of these diseases, but the underlying immune states and their clinical implications remain poorly understood. Multiomic factor analysis (MOFA) allows unsupervised data exploration across multiple data types, identifying major axes of variation and associating these with underlying molecular processes. We hypothesized that applying MOFA to multiomic data obtained from blood might uncover hidden sources of variance and provide pathophysiological insights linked to clinical needs. Here we compile a longitudinal multiomic dataset of the systemic immune landscape in both ACS and CCS (n = 62 patients in total, n = 15 women and n = 47 men) and validate this in an external cohort (n = 55 patients in total, n = 11 women and n = 44 men). MOFA reveals multicellular immune signatures characterized by distinct monocyte, natural killer and T cell substates and immune-communication pathways that explain a large proportion of inter-patient variance. We also identify specific factors that reflect disease state or associate with treatment outcome in ACS as measured using left ventricular ejection fraction. Hence, this study provides proof-of-concept evidence for the ability of MOFA to uncover multicellular immune programs in cardiovascular disease, opening new directions for mechanistic, biomarker and therapeutic studies.


  • Targeting the tissue factor coagulation initiation complex prevents antiphospholipid antibody development

    by Nadine Mueller-Calleja, Kristin Grunz, Thanh Son Nguyen, Jens Posma, Denise Pedrosa, Myriam Meineck, Anne Hollerbach, Johannes Braun, Sabine Muth, Hansjoerg Schild, et al.

    Antiphospholipid antibodies (aPL) in primary or secondary antiphospholipid syndrome (APS) are a major cause for acquired thrombophilia, but specific interventions preventing autoimmune aPL development are an unmet clinical need. Although autoimmune aPL cross react with various coagulation regulatory proteins, lipid-reactive aPL, including those derived from patients with COVID-19, recognize the endolysosomal phospholipid lysobisphosphatidic acid presented by the cell surface–expressed endothelial protein C receptor. This specific recognition leads to complement-mediated activation of tissue factor (TF)–dependent proinflammatory signaling and thrombosis. Here, we show that specific inhibition of the TF coagulation initiation complex with nematode anticoagulant protein c2 (NAPc2) prevents the prothrombotic effects of aPL derived from patients with COVID-19 in mice and the aPL–induced proinflammatory and prothrombotic activation of monocytes. The induction of experimental APS is dependent on the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex, and NAPc2 suppresses monocyte endosomal reactive oxygen species production requiring the TF cytoplasmic domain and interferon-α secretion from dendritic cells. Latent infection with murine cytomegalovirus causes TF cytoplasmic domain–dependent development of persistent aPL and circulating phospholipid-reactive B1 cells, which is prevented by short-term intervention with NAPc2 during acute viral infection. In addition, treatment of lupus prone MRL-lpr mice with NAPc2, but not with heparin, suppresses dendritic-cell activation in the spleen, aPL production and circulating phospholipid-reactive B1 cells, and attenuates lupus pathology. These data demonstrate a convergent TF-dependent mechanism of aPL development in latent viral infection and autoimmune disease and provide initial evidence that specific targeting of the TF initiation complex has therapeutic benefits beyond currently used clinical anticoagulant strategies.


  • Open Access

    Supporting oral communication in language learning through the fictitious identity technique

    by Katrin Saar, Terje Loogus, Krista Uibu

    Kui keeleliste osaoskuste õpetamine võõrkeeletunnis tavaliselt probleeme ei valmista, siis õpetajatele teeb muret õpilaste vähene suhtlusvalmidus. Probleemi aitavad vähendada suhtlussõbralik ja õppijaid motiveeriv keskkond, samuti loovust nõudvad õppijakesksed ning sihtkeele kultuuriruumi vastu huvi tekitavad ülesanded. Seda võimaldab simulatsioon fiktiivse identiteedi kasutamisega. Siinse sekkumisuuringu eesmärk oli välja selgitada, kuidas toetab fiktiivse identiteedi kui keeleõppemeetodi kasutamine üliõpilaste suhtlusvalmidust saksa keeles rääkimisel. Tulemustest järeldub, et meetod toetab üliõpilaste suhtlusvalmidust vaid osaliselt. Positiivsete külgedena märgiti, et fiktiivne identiteet aitab olla rohkem avatum ja spontaansem oma tegelaskujust rääkimisel. Ühtlasi paneb see otsima uusi väljendeid ja sõnu ning kiirendab sisseelamist saksakeelsesse maailma. Samas võivad selle meetodi ülesanded põhjustada rahulolematust. Osa üliõpilasi arvas, et ilma fiktiivse identiteedita oleksid nad tundides suhelnud sama palju. Negatiivset mõju avaldavate teguritena nimetati segadust erinevate identiteetide kasutamisel ja vähest huvi uue tegelaskuju väljamõtlemisel. Meetodis nähti eelkõige võimalust, kuidas keeleoskust aktiivselt arendada.  Summary

  • Open Access

    In Prostate Cancer Cells Cytokines Are Early Responders to Gravitational Changes Occurring in Parabolic Flights

    by Herbert Schulz, Dorothea Dietrichs, Markus Wehland, Thomas J. Corydon, Ruth Hemmersbach, Christian Liemersdorf, Daniela Melnik, Norbert Hübner, Kathrin Saar, Manfred Infanger, et al.

    The high mortality in men with metastatic prostate cancer (PC) establishes the need for diagnostic optimization by new biomarkers. Mindful of the effect of real microgravity on metabolic pathways of carcinogenesis, we attended a parabolic flight (PF) mission to perform an experiment with the PC cell line PC-3, and submitted the resulting RNA to next generation sequencing (NGS) and quantitative real-time PCR (qPCR). After the first parabola, alterations of the F-actin cytoskeleton-like stress fibers and pseudopodia are visible. Moreover, numerous significant transcriptional changes are evident. We were able to identify a network of relevant PC cytokines and chemokines showing differential expression due to gravitational changes, particularly during the early flight phases. Together with differentially expressed regulatory lncRNAs and micro RNAs, we present a portfolio of 298 potential biomarkers. Via qPCR we identified IL6 and PIK3CB to be sensitive to vibration effects and hypergravity, respectively. Per NGS we detected five upregulated cytokines (CCL2, CXCL1, IL6, CXCL2, CCL20), one zink finger protein (TNFAIP3) and one glycoprotein (ICAM1) related to c-REL signaling and thus relevant for carcinogenesis as well as inflammatory aspects. We found regulated miR-221 and the co-localized lncRNA MIR222HG induced by PF maneuvers. miR-221 is related to the PC-3 growth rate and MIR222HG is a known risk factor for glioma susceptibility. These findings in real microgravity may further improve our understanding of PC and contribute to the development of new diagnostic tools.


  • Open Access

    Protective immune trajectories in early viral containment of non-pneumonic SARS-CoV-2 infection

    by Kami Pekayvaz, Alexander Leunig, Rainer Kaiser, Markus Joppich, Sophia Brambs, Aleksandar Janjic, Oliver Popp, Daniel Nixdorf, Valeria Fumagalli, Nora Schmidt, et al.

    The antiviral immune response to SARS-CoV-2 infection can limit viral spread and prevent development of pneumonic COVID-19. However, the protective immunological response associated with successful viral containment in the upper airways remains unclear. Here, we combine a multi-omics approach with longitudinal sampling to reveal temporally resolved protective immune signatures in non-pneumonic and ambulatory SARS-CoV-2 infected patients and associate specific immune trajectories with upper airway viral containment. We see a distinct systemic rather than local immune state associated with viral containment, characterized by interferon stimulated gene (ISG) upregulation across circulating immune cell subsets in non-pneumonic SARS-CoV2 infection. We report reduced cytotoxic potential of Natural Killer (NK) and T cells, and an immune-modulatory monocyte phenotype associated with protective immunity in COVID-19. Together, we show protective immune trajectories in SARS-CoV2 infection, which have important implications for patient prognosis and the development of immunomodulatory therapies.


  • Open Access

    Vascular Tissue Specific miRNA Profiles Reveal Novel Correlations with Risk Factors in Coronary Artery Disease

    by Katrīna D. Neiburga, Baiba Vilne, Sabine Bauer, Dario Bongiovanni, Tilman Ziegler, Mark Lachmann, Simon Wengert, Johann S. Hawe, Ulrich Güldener, Annie M. Westerlund, et al.

    Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Non-coding RNAs have already been linked to CVD development and progression. While microRNAs (miRs) have been well studied in blood samples, there is little data on tissue-specific miRs in cardiovascular relevant tissues and their relation to cardiovascular risk factors. Tissue-specific miRs derived from Arteria mammaria interna (IMA) from 192 coronary artery disease (CAD) patients undergoing coronary artery bypass grafting (CABG) were analyzed. The aims of the study were 1) to establish a reference atlas which can be utilized for identification of novel diagnostic biomarkers and potential therapeutic targets, and 2) to relate these miRs to cardiovascular risk factors. Overall, 393 individual miRs showed sufficient expression levels and passed quality control for further analysis. We identified 17 miRs–miR-10b-3p, miR-10-5p, miR-17-3p, miR-21-5p, miR-151a-5p, miR-181a-5p, miR-185-5p, miR-194-5p, miR-199a-3p, miR-199b-3p, miR-212-3p, miR-363-3p, miR-548d-5p, miR-744-5p, miR-3117-3p, miR-5683 and miR-5701–significantly correlated with cardiovascular risk factors (correlation coefficient >0.2 in both directions, p-value (p < 0.006, false discovery rate (FDR) <0.05). Of particular interest, miR-5701 was positively correlated with hypertension, hypercholesterolemia, and diabetes. In addition, we found that miR-629-5p and miR-98-5p were significantly correlated with acute myocardial infarction. We provide a first atlas of miR profiles in IMA samples from CAD patients. In perspective, these miRs might play an important role in improved risk assessment, mechanistic disease understanding and local therapy of CAD.


  • Open Access

    Impulsivity is a heritable trait in rodents and associated with a novel quantitative trait locus on chromosome 1

    by Bianca Jupp, Silvia Pitzoi, Enrico Petretto, Adam C. Mar, Yolanda Pena Oliver, Emily R. Jordan, Stephanie Taylor, Santosh S. Atanur, Prashant K. Srivastava, Kathrin Saar, et al.

    Impulsivity describes the tendency to act prematurely without appropriate foresight and is symptomatic of a number of neuropsychiatric disorders. Although a number of genes for impulsivity have been identified, no study to date has carried out an unbiased, genome-wide approach to identify genetic markers associated with impulsivity in experimental animals. Herein we report a linkage study of a six-generational pedigree of adult rats phenotyped for one dimension of impulsivity, namely premature responding on the five-choice serial reaction time task, combined with genome wide sequencing and transcriptome analysis to identify candidate genes associated with the expression of the impulsivity trait. Premature responding was found to be heritable (h2 = 13–16%), with significant linkage (LOD 5.2) identified on chromosome 1. Fine mapping of this locus identified a number of polymorphic candidate genes, however only one, beta haemoglobin, was differentially expressed in both the founder strain and F6 generation. These findings provide novel insights into the genetic substrates and putative neurobiological mechanisms of impulsivity with broader translational relevance for impulsivity-related disorders in humans.


  • Open Access

    Statin-induced myopathic changes in primary human muscle cells and reversal by a prostaglandin F2 alpha analogue

    by Stefanie Anke Grunwald, Oliver Popp, Stefanie Haafke, Nicole Jedraszczak, Ulrike Grieben, Kathrin Saar, Giannino Patone, Wolfram Kress, Elisabeth Steinhagen-Thiessen, Gunnar Dittmar, et al.

    Statin-related muscle side effects are a constant healthcare problem since patient compliance is dependent on side effects. Statins reduce plasma cholesterol levels and can prevent secondary cardiovascular diseases. Although statin-induced muscle damage has been studied, preventive or curative therapies are yet to be reported. We exposed primary human muscle cell populations (n = 22) to a lipophilic (simvastatin) and a hydrophilic (rosuvastatin) statin and analyzed their expressome. Data and pathway analyses included GOrilla, Reactome and DAVID. We measured mevalonate intracellularly and analyzed eicosanoid profiles secreted by human muscle cells. Functional assays included proliferation and differentiation quantification. More than 1800 transcripts and 900 proteins were differentially expressed after exposure to statins. Simvastatin had a stronger effect on the expressome than rosuvastatin, but both statins influenced cholesterol biosynthesis, fatty acid metabolism, eicosanoid synthesis, proliferation, and differentiation of human muscle cells. Cultured human muscle cells secreted ω-3 and ω-6 derived eicosanoids and prostaglandins. The ω-6 derived metabolites were found at higher levels secreted from simvastatin-treated primary human muscle cells. Eicosanoids rescued muscle cell differentiation. Our data suggest a new aspect on the role of skeletal muscle in cholesterol metabolism. For clinical practice, the addition of omega-n fatty acids might be suitable to prevent or treat statin-myopathy.


  • Open Access

    Thyroid cancer cells in space during the TEXUS-53 sounding rocket mission – The THYROID Project

    by Sascha Kopp, Marcus Krüger, Stefan Feldmann, Hergen Oltmann, Andreas Schütte, Burkhard Schmitz, Johann Bauer, Herbert Schulz, Kathrin Saar, Norbert Huebner, et al.

    Human follicular thyroid cancer cells (FTC-133) were sent to space via a sounding rocket during the TEXUS-53 mission to determine the impact of short-term microgravity on these cells. To enable cell culture and fixation in real microgravity, an automated experiment container (EC) was constructed. In order to ensure safe cell culture, cell-chambers consisting of polycarbonate (PC) material were used. They were highly biocompatible as proved by measuring cell survival using Annexin V flow cytometry. In the follow-up experiment, FTC-133 cells were sent to space via a sounding rocket and were fixed before and after the microgravity (µg) phase with RNAlater. In addition, cells were tested for reactions on hypergravity (hyper-g) as much as 18 g to determine whether worst case acceleration during launch can have an influence on the cells. We investigated genes belonging to biological processes such as cytoskeleton, cell adhesion, tumor growth, angiogenesis and apoptosis. Pathway analyses revealed central functions of VEGFA and EGF. EGF upregulates aspartate beta-hydroxylase (ASPH) which is influencing CASP3. Hyper-g induced a significant up-regulation of TUBB1, VIM, RDX, CAV1, VEGFA and BCL2. FTC-133 cells grown in an automated EC exposed to µg revealed moderate gene expression changes indicating their survival in orbit.


  • Open Access

    A prostaglandin alpha F2 analog protects from statin-induced myopathic changes in primary human muscle cells

    by Stefanie Anke Grunwald, Oliver Popp, Stefanie Haafke, Nicole Jedraszczak, Ulrike Grieben, Kathrin Saar, Giannino Patone, Wolfram Kress, Elisabeth Steinhagen-Thiessen, Gunnar Dittmar, et al.

    Statin-related muscle side effects are a constant healthcare problem since patient compliance is dependent on side effects. Statins reduce plasma cholesterol levels and can prevent secondary cardiovascular disease. Although statin-induced muscle damage has been studied, preventive or curative therapies are yet to be reported. We exposed primary human muscle cell populations (n=25) to a lipophilic (simvastatin) and a hydrophilic (rosuvastatin) statin and analyzed their expressome. Data and pathway analyses included GOrilla, Reactome and DAVID. We measured mevalonate intracellularly and analyzed eicosanoid profiles secreted by human muscle cells. Functional assays included proliferation and differentiation quantification. More than 1800 transcripts and 900 proteins were differentially expressed after exposure to statins. Simvastatin had a stronger effect on the expressome than rosuvastatin, but both statins influenced cholesterol biosynthesis, fatty acid metabolism, eicosanoid synthesis, proliferation, and differentiation of human muscle cells. Cultured human muscle cells secreted ω-3 and ω-6 derived eicosanoids and prostaglandins. The ω-6 derived metabolites were found at higher levels secreted from simvastatin-treated primary human muscle cells. Eicosanoids rescued muscle cell differentiation. Our data suggest a new aspect on the role of skeletal muscle in cholesterol metabolism. For clinical practice, the addition of omega-n fatty acids could be suitable to prevent or treat statin-myopathy.