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The Immunological Proteome Resource (ImmPRes;http://immpres.co.uk/) is an open access public resource integrating proteomic data generated by large-scale mass-spectrometry analysis of murine hematopoietic populations. The initial focus is T lymphocytes and how their proteomes are shaped by immune activation, environment, and intracellular signalling pathways with an aim to expand it to B cells and innate immune cells. It is a multidisciplinary effort between immunology and mass spectrometry-based labs with the objective to help define an in-depth high-quality map of immune cell proteomes. Maintaining data reproducibility and integrity are a priority within the resource, thus there is an in-depth protocols section explaining in detail the sample processing and the mass spectrometry-based analysis. ImmPRes provides open access to proteomic datasets covering a wide range of murine leukocyte populations with analysis of copy numbers per cell of > 10,000 proteins, enabling new understanding of lymphocyte phenotypes. All data is accessible via a simple graphical interface that supports easy interrogation of the data and options to download data summaries and raw data files.

RationaleNeutrophils are important in the pathophysiology of COVID19 but the molecular changes contributing to altered neutrophil phenotypes following SARS-CoV-2 infection are not fully understood.ObjectivesTo use quantitative mass spectrometry-based proteomics to explore neutrophil phenotypes following acute SARS-CoV-2 infection and during recovery.MethodsProspective observational study of hospitalised patients with PCR-confirmed SARS-CoV-2 infection (May 2020-December 2020). Patients were enrolled within 96 hours of admission, with longitudinal sampling up to 29 days. Control groups comprised non-COVID19 acute lower respiratory tract infection (LRTI) and age-matched non-infected controls. Neutrophils isolated from peripheral blood were processed for mass spectrometry. COVID19 severity and recovery were defined using the WHO ordinal scale.Measurements and Main Results84 COVID19 patients were included and compared to 91 LRTI patients and 42 controls. 5,800 neutrophil proteins were identified and 1,748 proteins were significantly different (q-valueConclusionsSARS-CoV-2 infection results in the sustained presence of recirculating neutrophils with distinct metabolic profiles and altered capacities to respond to migratory signals and cues from other immune cells, pathogens or cytokines.Scientific Knowledge on the SubjectInflammation is the primary driver of morbidity and mortality in severe COVID19. Type I interferon responses, T-cell exhaustion, cytokine storm, emergency myelopoiesis, myeloid compartment dysregulation and procoagulant pathway activation are well established contributors to COVID19 disease severity. Neutrophils play an important role in COVID19, with elevated neutrophil-to-lymphocyte ratios and the emergence of a circulating immature neutrophil population in individuals with severe symptoms. Neutrophil infiltration in the lungs coupled with the release of neutrophil extracellular traps has also been reported in severe and fatal COVID19. The aim of this study was to quantitatively map the proteomes of peripheral blood neutrophils from a cohort of hospitalised COVID19 patients to understand how SARS-CoV-2 infection changes neutrophil phenotypes and functional capacity.What this study adds to the fieldHigh-resolution mass spectrometry was used to characterise the proteomes of peripheral blood neutrophils from >200 individuals at different stages of disease. This work has comprehensively mapped neutrophil molecular changes associated with mild and severe COVID19 and identified significant quantitative changes in more than 1700 proteins in neutrophils from patients hospitalised with COVID19 versus patients with non-COVID19 acute respiratory infections. The study identifies neutrophil protein signatures associated with COVID19 disease severity. The data also show that alterations in neutrophil proteomes can persist in fully recovered patients and identify distinct neutrophil proteomes in recovered versus non recovered patients. Our study provides novel insights into neutrophil responses during acute COVID19 and reveals that altered neutrophil phenotypes persist in convalescent COVID19 patients.

Using high resolution quantitative mass spectrometry we have generated in-depth proteome maps of human and mouseex vivoandin vitromicroglia. We reveal a tenfold difference in protein content ofex vivoandin vitrocells and fundamental differences in protein expression related to protein synthesis, metabolism, microglia markers and environmental sensors. While human and mouse microglia are different in their proteomes, the species differences are smaller than the changes induced by cell culture. Remarkably, xenografting human microglia derived from human stem cells into mouse brain restores thein vivo-like microglia proteomic signature including reduction in the total amount of protein, energy demand and protein synthesis, and re-expression of homeostatic microglia markers. We identify more than 9000 microglia proteins and discuss how they relate to microglia function. This data provides a vital proteomic resource for understandingin vitroandex vivomicroglia phenotypes.