Project description:Neutrophils provide immune protection against pathogens but also may promote tissue injury in inflammatory diseases. Although neutrophils are generally considered as a relatively homogeneous population, evidence for heterogeneity is emerging. Under steady-state conditions, neutrophil heterogeneity may arise from ageing and the replenishment by newly released neutrophils from the bone marrow. We used microarray to globally analyze gene expression in aged neutrophils and characterize the inflammatory programs that are activated during the aging process in the circulation. Control, aged and activated neutrophils were sorted directly from mouse blood for RNA extraction and hybridization on Affymetrix microarrays. We transfused whole blood and harvested donor neutrophils marked by the CD45.1 allele 6h later to derive neutrophils that had truly aged in vivo. Sorted neutrophils were compared to control donor neutrophils that had been transferred for only 10 min. Additionally, we harvested circulating neutrophils from TNF-? treated mice for comparison with neutrophils activated by systemic inflammation.
Project description:Myeloid-derived suppressor cells (MDSCs) have the capacity to suppress T cell-mediated immune responses, and impact clinical outcome of cancer, infections and transplantation settings. Although MDSCs were initially described as bone-marrow-derived immature myeloid cells (either monocytic [m-MDSC] or granulocytic [g-MDSC]), also mature neutrophils have been shown to exert MDSC activity towards T cells, in ways that so far remained unclear. In this study, we demonstrate that human neutrophils – both from healthy donors and cancer patients – do not exert MDSC activity unless they are activated. Using neutrophils with genetically well-defined defects, we found that reactive oxygen species (ROS) and granule-derived constituents are required for MDSC activity after direct CD11b-dependent neutrophil-T cell interactions. Besides these cellular interactions, neutrophils were engaged in the uptake of pieces of T cell membrane, a process called trogocytosis. Together, these interactions led to changes in T cell morphology, mitochondrial dysfunction and ATP depletion, as indicated by electron microscopy, mass spectrometry and metabolic parameters. Our studies characterize the different steps by which activated mature neutrophils induce functional T cell non-responsiveness and irreparable cell damage.
Project description:Neutrophils provide immune protection against pathogens but also may promote tissue injury in inflammatory diseases. Although neutrophils are generally considered as a relatively homogeneous population, evidence for heterogeneity is emerging. Under steady-state conditions, neutrophil heterogeneity may arise from ageing and the replenishment by newly released neutrophils from the bone marrow. We used microarray to globally analyze gene expression in aged neutrophils and characterize the inflammatory programs that are activated during the aging process in the circulation.
Project description:While critical for host defense, innate immune cells are also pathologic drivers of acute respiratory distress syndrome (ARDS). Innate immune dynamics during COVID-19 ARDS, compared to ARDS from other respiratory pathogens, is unclear. Moreover, mechanisms underlying beneficial effects of dexamethasone during severe COVID-19 remain elusive. Using scRNA-seq and plasma proteomics, we discovered that compared to bacterial ARDS, COVID-19 was associated with expansion of distinct neutrophil states characterized by interferon (IFN) and prostaglandin (PG) signalling. Dexamethasone during severe COVID-19 depleted circulating neutrophils, altered IFNactive neutrophils, downregulated interferon-stimulated gene, and activated IL1R2+ve neutrophils. Dexamethasone also expanded immunosuppressive immature neutrophils and remodeled cellular interactions by changing neutrophils from information receivers into information providers. Male patients had higher proportions of IFNactive neutrophils, preferential steroid-induced immature neutrophil expansion, and possibly different effects on outcome. Our single-cell atlas (www.biernaskielab.ca/COVID_neutrophil) defines COVID-19-enriched neutrophil states and molecular mechanisms of dexamethasone action to develop targeted immunotherapies for severe COVID-19.
Project description:Compared to circulating neutrophils (NC cells), splenic neutrophils (NBH cells) have an activated phenotype and enhanced B cell-helper activity. The transcriptome analysis of splenic and circulating neutrophils was performed to verify whether the enhanced B cell-helper activity of splenic neutrophils correlated with a specific gene signature. Unstimulated neutrophils were FACS sorted from the peripheral blood and spleen of six adult healthy subjects for RNA isolation and Agilent analysis.