Biology subjects

Escaliere, B.

Publications and source records attributed to Escaliere, B..

4 recordsLinked to original sources

bioRxiv2026

In vitro-generated murine monocyte-derived dendritic cells habor a unique identity compared to other mononuclear phagocytes, largely conserved with their human and putative in vivo counterparts.

Whether the cells differentiating in vitro from total murine bone marrow (BM) cultures with GM-CSF +/- IL-4 are homologous to the human cells derived in vitro from purified circulating monocytes (Mo) cultured with GM-CSF and IL-4, mostly correspond to monocyte-derived dendritic cells (moDCs) or rather to macrophages (MFs), and have in vivo counterparts, is debated. It has been proposed to define cell types based on their ontogeny, leading to the proposal of excluding from the dendritic cell (DC) family the cells that do not arise from the common DC progenitors (CDP). However, recent discoveries support defining cell types rather by functions, or, as a surrogate, their instructive molecular networks. Indeed, Langerhans cells, Rorgt+ DCs, some cDC2As and human in vitro-derived moDCs do not arise from the CDP but exert hallmark DC functions instructed by specific transcriptomic modules shared with cDCs. Actually, the study of both LCs and moDCs has been key for dissecting DC biology. Yet, the existence of moDCs is put into questions. The functions once attributed to moDCs are now proposed to be exerted by type 2B conventional DCs (cDC2Bs) or type 3 DCs (DC3s) that have been characterized recently, harbor strongly overlapping phenotypes with moDCs and a similar mixed expression of genes from both the cDC and Mo/MF lineages, but a different ontogeny. To clarify these issues, we generated a transcriptomic atlas of in vitro-derived mononuclear phagocytes (MNPs). We show that moDCs are the only DC type arising in BM cultures in the presence of GM-CSF and IL-4. They express a unique transcriptomic and phenotypic signature, different from those of cDC2Bs and DC3s that are produced in FLT3-L cultures and appear to correspond to the same DC type differentiating though two different but converging ontogenetic paths. By harnessing the phenotypic and transcriptomic signatures identified from the analysis of our in vitro MNP atlas, we are able to identify in vivo a population of putative DCs differentiated from monocytes derived from the common monocyte-granulocyte progenitor (GMP), in a respiratory allergy model, specifically in the lungs of mice sensitized to house dust mite (HDM). Using the model of thioglycolate-induced peritonitis, we also characterized the CD226+ Mo-derived cells that have been reported to be moDCs or small cavity MFs (SCM) depending on studies. We showed that these cells are mainly differentiated from monocytes derived from the MDP, and split into two populations, one resembling MFs (SCMs) and the other one closer to lung moDCs but expressing distinct genes suggesting a different functional potential. Collectively, we show that the generation and characterization of specific MNP types in vitro can be harnessed to rigorously define their in vivo counterparts based on phenotypic analysis and gene module assessment, as we demonstrate for moDCs.

immunology↗

bioRxiv2024

Genome-wide CRISPR/Cas9 screen reveals factors that influence the susceptibility of tumor cells to NK cell-mediated killing

BackgroundNatural killer (NK) cells exhibit potent cytotoxic activity against various cancer cell types. Over the past five decades, numerous methodologies have been employed to elucidate the intricate molecular mechanisms underlying NK cell-mediated tumor control. While significant progress has been made in elucidating the interactions between NK cells and tumor cells, the regulatory factors governing NK cell-mediated tumor cell destruction are not yet fully understood. This includes the diverse array of tumor ligands recognized by NK cells and the mechanisms that NK cells employ to eliminate tumor cells. MethodsIn this study, we employed a genome-wide CRISPR/Cas9 screening approach in conjunction with functional cytotoxicity assays to delineate the proteins modulating the susceptibility of colon adenocarcinoma HCT-116 cells to NK cell-mediated cytotoxicity. ResultsAnalysis of guide RNA (gRNA) distribution in HCT-116 cells that survived co-incubation with NK cells identified ICAM-1 as a pivotal player in the NKp44-mediated immune synapse, with NKp44 serving as an activating receptor crucial for the elimination of HCT-116 tumor cells by NK cells. Furthermore, disruption of genes involved in the apoptosis or IFN-{gamma} signaling pathways conferred resistance to NK cell attack. We further dissected that NK cell-derived IFN-{gamma} promotes mitochondrial apoptosis in vitro and exerts control over B16-F10 lung metastases in vivo. ConclusionMonitoring ICAM-1 levels on the surface of tumor cells or modulating its expression should be considered in the context of NK cell-based therapy. Additionally, considering the diffusion properties of IFN-{gamma}, our findings highlight the potential of leveraging NK cell-derived IFN-{gamma} to enhance direct tumor cell killing and facilitate bystander effects via cytokine diffusion, warranting further investigation. WHAT IS ALREADY KNOWN ON THIS TOPICNK cells play a crucial role in identifying and eliminating various cancer cell types. However, the mechanisms that regulate NK cell-mediated destruction of tumor cells are not yet fully understood. This involves the array of tumor ligands that NK cells recognize and the processes they utilize to carry out tumor cell elimination. WHAT THIS STUDY ADDSOur research emphasizes the critical role of ICAM-1 in NKp44-mediated destruction of HCT-116 tumor cells. Additionally, we found that interfering with genes related to apoptosis or IFN-{gamma} signaling pathways increased resistance to NK cell attack. We showed that IFN-{gamma} produced by NK cells induces mitochondrial apoptosis in vitro and helps regulate B16-F10 lung metastases in vivo. HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICYGiven the ability of IFN-{gamma} to diffuse, our findings suggest that NK cell-derived IFN-{gamma} can be harnessed to directly kill tumor cells and trigger bystander effects through cytokine spread. This approach holds promise for further exploration. Additionally, assessing or manipulating ICAM-1 levels on tumor cell surfaces could enhance the effectiveness of NK cell-based therapies.

immunology↗

bioRxiv2024

Specific pre-plasma cell states and local proliferation at the dark zone - medulla interface characterize germinal center-derived plasma cell differentiation in lymph node

High affinity antibody-producing plasma cells (PC) generated in germinal centers (GC) are crucial for durable immunity after vaccination or infection. The selection of high affinity B cells in the GC light zone instructs PC differentiation in a subset of cells, but the cellular transitions and spatial organization of GC to PC differentiation remain poorly understood. Here, we have used a mouse model to track GC-derived B cells with integrative single-cell and spatial analyses in draining lymph node after immunization or infection. We first identified putative PrePC cells in scRNA-seq datasets, then enriched those cells through their specific surface phenotype for further analysis of their gene expression trajectories and BCR repertoire. We found a continuum of actively proliferating transitional states bridging selected LZ GC B cells and recently exported PCs, with gradually increasing levels of endoplasmic reticulum stress-associated genes and Ig transcripts. Spatial analyses revealed that recently differentiated PC continued their maturation and affinity-restricted proliferation at a previously uncharacterized interface between the DZ and extensions of the lymph node medulla. Our findings provide insights into the intermediate stages and microenvironmental factors involved in the differentiation of GC B cells into PC, with implications for vaccine development and understanding antibody responses.

immunology↗

bioRxiv2024

Plasmacytoid dendritic cells are dispensable or detrimental in murine systemic or respiratory viral infections

Plasmacytoid dendritic cells (pDCs) are major producers of type I/III interferons. As interferons are crucial for antiviral defense, pDCs are assumed to play an essential role in this process. However, robust evidence supporting this dogma is scarce. Genetic or pharmacological manipulations that eliminate pDC or disrupt their interferon production often affect other cells, confounding interpretation. To overcome this issue, we engineered pDC-less mice that are specifically and constitutively devoid of pDCs by expressing diphtheria toxin under coordinated control of the Siglech and Pacsin1 genes, uniquely co-expressed in pDCs. pDC-less mice mounted protective immunity against systemic infection with mouse Cytomegalovirus and showed higher survival and less lung immunopathology to intranasal infection with influenza virus and SARS-CoV2. Thus, contrary to the prevailing dogma, we revealed that pDCs and their interferons are dispensable or deleterious during several viral infections. pDC-less mice will enable rigorously reassessing the roles of pDCs in health and disease.

immunology↗