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Background: Acute kidney injury (AKI) is frequently observed in critically ill patients and is associated with a poor prognosis. AKI has recently moved into the focus of interest during the SARS-CoV-2 pandemic as high rates of AKI have been reported in severe COVID-19. We aimed to delineate cell type-specific molecular phenotypes associated with human AKI, including COVID-associated AKI. Methods: We analyzed human kidney tissues using histology and single-nuclei RNA sequencing. Samples included kidney biopsies obtained within 2 hours post mortem from patients who succumbed to critical illness with and without evidence of AKI. Samples also included tumor-adjacent normal kidney tissues obtained during surgeries. AKI cases included patients with severe courses of COVID-19 (COVID AKI) and patients with other types of critical illness associated with systemic inflammation (Non-COVID AKI). Postmortem kidney tissues obtained 30 min, 1 hour and 2 hours after death from a brain-dead patient without AKI were analyzed to assess the impact of post-mortem effects. Results: Single-nuclei sequencing from kidney tissues yielded data of high transcriptional depth, which allowed transcriptome-based identification and de-novo spatial reconstruction of kidney cells. Principal component and differential gene expression analyses indicated that the presence of clinically confirmed AKI was the primary driver of global kidney transcriptomes and that different molecular subtypes of AKI existed. In contrast, the sampling time post-mortem and the presence of COVID-19 had minor effects. Subclustering analyses of different kidney cell types identified subclasses of cells representing injured kidney tubular cells, which were marked by distinct biomarker expression and expression signatures signifying intrinsic responses to inflammation, an induction of epithelial-to-mesenchymal transition, and an upregulation of hitheto unrecognized novel receptor-ligand pairs. Conclusions: We provide the first cell type-specific molecular atlas of human AKI, revealing unanticipated disease subtypes and cell type-specific injury patterns.
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BACKGROUND: Reliable data on the course and treatment of pediatric COVID-19 ("corona virus disease 2019") in immunosuppressed patients with rheumatic diseases are missing. AIM: Delineation of individual strategies of the members of the Society for Pediatric Rheumatology (GKJR) in cases of COVID-19. METHODS: In May 2020 all GKJR members were invited to take part in an online survey. Opinion data regarding an approach using disease-modifying anti-rheumatic drugs (DMARD) in cases of COVID-19 as well as the readiness to use new therapeutic agents in patients in different stages of the disease were collected. RESULTS: A total of 71 respondents (27.3% of all contacted pediatric rheumatologists) took part in the survey. Of these 28.2% had treated patients with COVID-19. Over 95% of the respondents did not support a preventive adaptation of the anti-rheumatic treatment during the SARS-CoV2 pandemic. In the case of outpatients under immunosuppression with proven COVID-19 more than 50% of the respondents would refrain from administering intravenous high-dose steroids, cyclophosphamide, anti-CD20 antibodies as well as BAFF, CTLA4 and TNF-alpha blockades. Conversely, >70% of the respondents would continue the treatment with nonsteroidal anti-inflammatory drugs, hydroxychloroquine (HCQ), oral steroids, mycophenolate, IL1 blockade and immunoglobulins (Ig). In the case of inpatients 74.6% of respondents would consider targeted COVID-19 treatment. In stable patients with oxygen treatment (stage I) HCQ (18.3%), azithromycin (16.9%) and Ig (9.9%) were most frequently used. In cases of early signs (stage II) or a manifest cytokine storm (stage III) anakinra (40.8% for stage II and 46.5% for stage III), tocilizumab (26.8% and 40.8%, respectively), steroids (25.4% and 33.8%, respectively) and remdesivir (29.6% and 38.0%, respectively) were most frequently used. The need for a personalized approach based on the current clinical situation was emphasized by many respondents. CONCLUSION: The currently low prevalence of COVID-19 in Germany limits the general clinical experience. Therefore, the presented results have to be interpreted with caution and mostly as hypothetical treatment considerations. It is to be expected that there will always be a limited amount of evidence on pediatric COVID-19; therefore, a continuous and critical exchange of expert opinions on the treatment strategies is important.