Thomas Ulas - Academia.edu (original) (raw)

Papers by Thomas Ulas

Proceedings of the National Academy of Sciences

Macrophages are the principal immune cells of the epididymis and testis, but their origins, heter... more Macrophages are the principal immune cells of the epididymis and testis, but their origins, heterogeneity, development, and maintenance are not well understood. Here, we describe distinct populations of epididymal and testicular macrophages that display an organ-specific cellular identity. Combining in vivo fate-mapping, chimeric and parabiotic mouse models with in-depth cellular analyses, we found that CD64hiMHCIIlo and CD64loMHCIIhi macrophage populations of epididymis and testis arise sequentially from yolk sac erythro-myeloid progenitors, embryonic hematopoiesis, and nascent neonatal monocytes. While monocytes were the major developmental source of both epididymal and testicular macrophages, both populations self-maintain in the steady-state independent of bone marrow hematopoietic precursors. However, after radiation-induced macrophage ablation or during infection, bone marrow-derived circulating monocytes are recruited to the epididymis and testis, giving rise to inflammatory ...

BIOspektrum

The COVID-19 pandemic is leading to increasing numbers of patients all over the world. Reports on... more The COVID-19 pandemic is leading to increasing numbers of patients all over the world. Reports on a dysregulated immune system in the severe cases calls for a better characterization of the ongoing changes. To dissect COVID-19-driven immune host responses, we profiled whole blood transcriptomes enabling a data-driven stratification based on molecular phenotype. This analysis allowed prediction of patient subgroup-specific drug candidates targeting the dysregulated systemic immune response of the host.

Clinical and Translational Medicine

Dear Editor, Neonatal sepsis is a leading cause of childhood mortality worldwide particularly aff... more Dear Editor, Neonatal sepsis is a leading cause of childhood mortality worldwide particularly affecting preterm infants, who are often exposed to empirical antibiotics since sepsis biomarkers lack sensitivity in this patient group andmarkers predicting the risk of sepsis have not been identified yet.1,2 In our study, serum S100A8/A9 proved as an independent predictive marker of late-onset neonatal sepsis (LOS) in preterm infants, which for the first time offers the opportunity to change current treatment policies by improving antibiotic stewardship and timely individualized therapeutic intervention. Serum S100A8/A9 (also known as serum calprotectin) is an alarmin respective damage-associated molecular pattern (DAMP) that is rapidly released from myeloid cells upon stress or cell damage, acting then as secondary amplifier of inflammation.3 In adults, the S100A8/A9 serum level is used as one of the most sensitive biomarkers in inflammatory processes.4 Its value as sepsis marker in neonates remains unclear and needs to be tested. On the other hand, we previously identified S100A8/A9 as an essential sepsis-protective regulator of neonatal immunity5,6 with serum levels being physiologically increased after birth.7 Thereby, significantly higher levels in term compared to preterm infants6 suggest that low S100A8/A9 in neonates is associated with an increased risk of sepsis. However, other parameters potentially influencing neonatal S100A8/A9 serum levels are ill defined, wherefore the value of S100A8/A9 as an independent predictive marker of neonatal sepsis also remains to be demonstrated. A total of 289 preterm infants born below 32 gestational weekswere prospectively enrolled. In a case–control study, of 41 infants serum levels of S100A8/A9, C-reactive protein (CRP) and interleukin 6 (IL-6) were determined at the onset of neonatal sepsis and compared with 50 matched healthy controls (Table S1 and Methods in the Supporting Information). However, S100A8/A9 did not distinguish septic infants from healthy controls due to already elevated S100A8/A9 levels in nondiseased infants (Figure 1A).

SUMMARYThe SARS-CoV-2 pandemic is currently leading to increasing numbers of COVID-19 patients al... more SUMMARYThe SARS-CoV-2 pandemic is currently leading to increasing numbers of COVID-19 patients all over the world. Clinical presentations range from asymptomatic, mild respiratory tract infection, to severe cases with acute respiratory distress syndrome, respiratory failure, and death. Reports on a dysregulated immune system in the severe cases calls for a better characterization and understanding of the changes in the immune system. Here, we profiled whole blood transcriptomes of 39 COVID-19 patients and 10 control donors enabling a data-driven stratification based on molecular phenotype. Neutrophil activation-associated signatures were prominently enriched in severe patient groups, which was corroborated in whole blood transcriptomes from an independent second cohort of 30 as well as in granulocyte samples from a third cohort of 11 COVID-19 patients. Comparison of COVID-19 blood transcriptomes with those of a collection of over 2,800 samples derived from 11 different viral infecti...

Immunity, 2014

Macrophage activation is associated with profound transcriptional reprogramming. Although much pr... more Macrophage activation is associated with profound transcriptional reprogramming. Although much progress has been made in the understanding of macrophage activation, polarization, and function, the transcriptional programs regulating these processes remain poorly characterized. We stimulated human macrophages with diverse activation signals, acquiring a data set of 299 macrophage transcriptomes. Analysis of this data set revealed a spectrum of macrophage activation states extending the current M1 versus M2-polarization model. Network analyses identified central transcriptional regulators associated with all macrophage activation complemented by regulators related to stimulus-specific programs. Applying these transcriptional programs to human alveolar macrophages from smokers and patients with chronic obstructive pulmonary disease (COPD) revealed an unexpected loss of inflammatory signatures in COPD patients. Finally, by integrating murine data from the ImmGen project we propose a refined, activation-independent core signature for human and murine macrophages. This resource serves as a framework for future research into regulation of macrophage activation in health and disease.

Nature

Fast and reliable detection of patients with severe and heterogeneous illnesses is a major goal o... more Fast and reliable detection of patients with severe and heterogeneous illnesses is a major goal of precision medicine1,2. Patients with leukaemia can be identified using machine learning on the basis of their blood transcriptomes3. However, there is an increasing divide between what is technically possible and what is allowed, because of privacy legislation4,5. Here, to facilitate the integration of any medical data from any data owner worldwide without violating privacy laws, we introduce Swarm Learning—a decentralized machine-learning approach that unites edge computing, blockchain-based peer-to-peer networking and coordination while maintaining confidentiality without the need for a central coordinator, thereby going beyond federated learning. To illustrate the feasibility of using Swarm Learning to develop disease classifiers using distributed data, we chose four use cases of heterogeneous diseases (COVID-19, tuberculosis, leukaemia and lung pathologies). With more than 16,400 b...

ERJ Open Research

BackgroundImmune cells play a major role in the pathogenesis of COPD. Changes in the distribution... more BackgroundImmune cells play a major role in the pathogenesis of COPD. Changes in the distribution and cellular functions of major immune cells, such as alveolar macrophages (AMs) and neutrophils are well known; however, their transcriptional reprogramming and contribution to the pathophysiology of COPD are still not fully understood.MethodTo determine changes in transcriptional reprogramming and lipid metabolism in the major immune cell type within bronchoalveolar lavage fluid, we analysed whole transcriptomes and lipidomes of sorted CD45+Lin−HLA-DR+CD66b−Autofluorescencehi AMs from controls and COPD patients.ResultsWe observed global transcriptional reprogramming featuring a spectrum of activation states, including pro- and anti-inflammatory signatures. We further detected significant changes between COPD patients and controls in genes involved in lipid metabolism, such as fatty acid biosynthesis in GOLD2 patients. Based on these findings, assessment of a total of 202 lipid species...

Methods in Molecular Biology

Journal of Molecular and Cellular Cardiology

The stem cell-specific RNA-binding protein TRIM71/LIN-41 was the first identified target of the p... more The stem cell-specific RNA-binding protein TRIM71/LIN-41 was the first identified target of the pro-differentiation and tumor suppressor miRNA let-7. TRIM71 has essential functions in embryonic development and a proposed oncogenic role in several cancer types, such as hepatocellular carcinoma. Here, we show that TRIM71 regulates let-7 expression and activity via two independent mechanisms. On the one hand, TRIM71 enhances pre-let-7 degradation through its direct interaction with LIN28 and TUT4, thereby inhibiting let-7 maturation and indirectly promoting the stabilization of let-7 targets. On the other hand, TRIM71 represses the activity of mature let-7 via its RNA-dependent interaction with the RNA-Induced Silencing Complex (RISC) effector protein AGO2. We found that TRIM71 directly binds and stabilizes let-7 targets, suggesting that let-7 activity inhibition occurs on active RISCs. MiRNA enrichment analysis of several transcriptomic datasets from mouse embryonic stem cells and hum...

Identification of patients with life-threatening diseases including leukemias or infections such ... more Identification of patients with life-threatening diseases including leukemias or infections such as tuberculosis and COVID-19 is an important goal of precision medicine. We recently illustrated that leukemia patients are identified by machine learning (ML) based on their blood transcriptomes. However, there is an increasing divide between what is technically possible and what is allowed because of privacy legislation. To facilitate integration of any omics data from any data owner world-wide without violating privacy laws, we here introduce Swarm Learning (SL), a decentralized machine learning approach uniting edge computing, blockchain-based peer-to-peer networking and coordination as well as privacy protection without the need for a central coordinator thereby going beyond federated learning. Using more than 14,000 blood transcriptomes derived from over 100 individual studies with non-uniform distribution of cases and controls and significant study biases, we illustrate the feasib...

Genome Medicine

Background The SARS-CoV-2 pandemic is currently leading to increasing numbers of COVID-19 patient... more Background The SARS-CoV-2 pandemic is currently leading to increasing numbers of COVID-19 patients all over the world. Clinical presentations range from asymptomatic, mild respiratory tract infection, to severe cases with acute respiratory distress syndrome, respiratory failure, and death. Reports on a dysregulated immune system in the severe cases call for a better characterization and understanding of the changes in the immune system. Methods In order to dissect COVID-19-driven immune host responses, we performed RNA-seq of whole blood cell transcriptomes and granulocyte preparations from mild and severe COVID-19 patients and analyzed the data using a combination of conventional and data-driven co-expression analysis. Additionally, publicly available data was used to show the distinction from COVID-19 to other diseases. Reverse drug target prediction was used to identify known or novel drug candidates based on finding from data-driven findings. Results Here, we profiled whole bloo...

'Severe Acute Respiratory Syndrome - Coronavirus-2' (SARS-CoV-2) infection causes... more 'Severe Acute Respiratory Syndrome - Coronavirus-2' (SARS-CoV-2) infection causes Coronavirus Disease 2019 (COVID-19), a mild to moderate respiratory tract infection in the majority of patients. A subset of patients, however, progresses to severe disease and respiratory failure with acute respiratory distress syndrome (ARDS). Severe COVID-19 has been associated with increased neutrophil counts and dysregulated immune responses. The mechanisms of protective immunity in mild forms and the pathogenesis of dysregulated inflammation in severe courses of COVID-19 remain largely unclear. Here, we combined two single-cell RNA-sequencing technologies and single-cell proteomics in whole blood and peripheral blood mononuclear cells (PBMC) to determine changes in immune cell composition and activation in two independent dual-center patient cohorts (n=46 + n=54 COVID-19 samples), each with mild and severe cases of COVID-19. We observed a specific increase of HLA-DR high CD11c high inflammatory monocytes that displayed a strong interferon (IFN)-stimulated gene signature in patients with mild COVID-19, which was absent in severe disease. Instead, we found evidence of emergency myelopoiesis, marked by the occurrence of immunosuppressive pre-neutrophils and immature neutrophils and populations of dysfunctional and suppressive mature neutrophils, as well as suppressive HLA-DR low monocytes in severe COVID-19. Our study provides detailed insights into systemic immune response to SARS-CoV-2 infection and it reveals profound alterations in the peripheral myeloid cell compartment associated with severe courses of COVID-19.