Project description:Lymph nodes (LNs) are essential hubs for the induction and regulation of immune responses. Immune activation, either systemic or local, is accompanied by the lymph node swelling response, which results in up to threefold expansion in volume. Increased immigration of immune cells via the blood vasculature causes the LN swelling response with retention of lymphocytes and myeloid cells in perivascular niches. The perivascular niche is supported by fibroblastic cells known as mural cells (vascular smooth muscle cells (VSMCs) and pericytes) and by perivascular reticular cells (PRCs) that connect the perivascular niche to the fibroblastic reticular cell (FRC) network. Here, we used high-resolution confocal microscopy, flow cytometry, single cell transcriptomics and cell fate mapping in mouse models to delineate VSMC and PRC phenotypes and differentiation during development in different LN entities.
Project description:The lymph node is home to resident macrophage populations that are essential for healthy immune function and homeostasis. They are involved in multiple processes including the initiation of the local response to pathogens, halting viral and bacterial spread, and clearance of apoptotic cells, but the macrophage niche and factors that create it are largely undefined. Here we analyse fibroblastic reticular cells (FRCs) as an essential component of the lymph node macrophage niche using single-cell RNA-sequencing. Our analysis revealed that most reticular cell subsets within lymph nodes expressed master macrophage regulator CSF1. We further show that signalling through CSF1R was sufficient to support macrophage development, while in the presence of LPS, FRCs underwent a mechanistic switch and maintained support through CSF1R-independent mechanisms. Our data reveal a critically important role for FRCs in the creation of the parenchymal macrophage niche within LNs.
Project description:Secondary lymphoid organs are organized by fibroblastic reticular cells (FRCs), which direct immune cell positioning and support adaptive immunity. However, the mechanisms driving FRC subset differentiation remain unclear. To uncover signaling pathways involved in this process, we performed ATAC-seq on lymph node FRCs lacking Notch2. Our data reveal chromatin remodeling changes in the absence of Notch signaling.
Project description:The interaction of immune cells in the lymph node microenvironment depends on the infrastructure and molecular cues provided by fibroblastic reticular cells (FRCs). In addition, concentric layers of still poorly defined mural cells, including vascular smooth muscle cells (VSMCs), are involved in positioning and regulating immune cell interactions. Here, we used high-resolution confocal microscopy, flow cytometry, single cell transcriptomics and trajectory analysis to delineate VSMC and PRC phenotypes and differentiation during development in different LN entities.
Project description:Secondary lymphoid organs are structurally organized by fibroblastic reticular cells (FRCs), which support immune cell positioning and adaptive immune responses. However, the mechanisms driving the differentiation of FRCs into distinct functional subsets remain unclear. To investigate the role of Notch2 signaling in this process, we performed single-cell RNA sequencing (10x Genomics) on lymph node FRCs lacking Notch2 expression. Our dataset highlights how this pathway contributes to FRC differentiation.
Project description:Lymph node (LN) stromal cells, particularly fibroblastic reticular cells (FRCs), provide critical structural support and regulate immunity, tolerance and transport properties of LNs. In many tumors, LN metastasis is predictive of poor prognosis, however, stromal contribution to the evolving microenvironment of tumor draining LNs (TDLN) remains poorly understood. Here we present comparative transcriptional data of resting and TDLN FRCs after different time points of tumor drainage. FRCs were isolated from lymph nodes and FACS sorted based on the expression of CD45-, CD31- and PDPN+
