| 1. |
- Mäe, Maarja Andaloussi, et al.
(författare)
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Single-Cell Analysis of Blood-Brain Barrier Response to Pericyte Loss
- 2021
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Ingår i: Circulation Research. - : Lippincott Williams & Wilkins. - 0009-7330 .- 1524-4571. ; 128:4, s. E46-E62
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Pericytes are capillary mural cells playing a role in stabilizing newly formed blood vessels during development and tissue repair. Loss of pericytes has been described in several brain disorders, and genetically induced pericyte deficiency in the brain leads to increased macromolecular leakage across the blood-brain barrier (BBB). However, the molecular details of the endothelial response to pericyte deficiency remain elusive.Objective: To map the transcriptional changes in brain endothelial cells resulting from lack of pericyte contact at single-cell level and to correlate them with regional heterogeneities in BBB function and vascular phenotype.Methods and Results: We reveal transcriptional, morphological, and functional consequences of pericyte absence for brain endothelial cells using a combination of methodologies, including single-cell RNA sequencing, tracer analyses, and immunofluorescent detection of protein expression in pericyte-deficient adult Pdgfb(ret/ret) mice. We find that endothelial cells without pericyte contact retain a general BBB-specific gene expression profile, however, they acquire a venous-shifted molecular pattern and become transformed regarding the expression of numerous growth factors and regulatory proteins. Adult Pdgfb(ret/ret) brains display ongoing angiogenic sprouting without concomitant cell proliferation providing unique insights into the endothelial tip cell transcriptome. We also reveal heterogeneous modes of pericyte-deficient BBB impairment, where hotspot leakage sites display arteriolar-shifted identity and pinpoint putative BBB regulators. By testing the causal involvement of some of these using reverse genetics, we uncover a reinforcing role for angiopoietin 2 at the BBB.Conclusions: By elucidating the complexity of endothelial response to pericyte deficiency at cellular resolution, our study provides insight into the importance of brain pericytes for endothelial arterio-venous zonation, angiogenic quiescence, and a limited set of BBB functions. The BBB-reinforcing role of ANGPT2 (angiopoietin 2) is paradoxical given its wider role as TIE2 (TEK receptor tyrosine kinase) receptor antagonist and may suggest a unique and context-dependent function of ANGPT2 in the brain.
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| 2. |
- Banas, Magdalena, et al.
(författare)
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Chemerin Is an Antimicrobial Agent in Human Epidermis
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:3
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Tidskriftsartikel (refereegranskat)abstract
- Chemerin, a chemoattractant ligand for chemokine-like receptor 1 (CMKLR1) is predicted to share similar tertiary structure with antibacterial cathelicidins. Recombinant chemerin has antimicrobial activity. Here we show that endogenous chemerin is abundant in human epidermis, and that inhibition of bacteria growth by exudates from organ cultures of primary human skin keratinocytes is largely chemerin-dependent. Using a panel of overlapping chemerin-derived synthetic peptides, we demonstrate that the antibacterial activity of chemerin is primarily mediated by Val 66 -Pro 85, which causes direct bacterial lysis. Therefore, chemerin is an antimicrobial agent in human skin.
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| 3. |
- Dinh, Thanh Theresa, et al.
(författare)
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An NKX-COUP-TFII morphogenetic code directs mucosal endothelial addressin expression
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Immunoglobulin family and carbohydrate vascular addressins encoded by Madcam1 and St6gal1 control lymphocyte homing into intestinal tissues, regulating immunity and inflammation. The addressins are developmentally programmed to decorate endothelial cells lining gut post-capillary and high endothelial venules (HEV), providing a prototypical example of organ- and segment-specific endothelial specialization. We identify conserved NKX-COUP-TFII composite elements (NCCE) in regulatory regions of Madcam1 and St6gal1 that bind intestinal homeodomain protein NKX2-3 cooperatively with venous nuclear receptor COUP-TFII to activate transcription. The Madcam1 element also integrates repressive signals from arterial/capillary Notch effectors. Pan-endothelial COUP-TFII overexpression induces ectopic addressin expression in NKX2-3+ capillaries, while NKX2-3 deficiency abrogates expression by HEV. Phylogenetically conserved NCCE are enriched in genes involved in neuron migration and morphogenesis of the heart, kidney, pancreas and other organs. Our results define an NKX-COUP-TFII morphogenetic code that targets expression of mucosal vascular addressins.
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| 4. |
- Pærregaard, Simone Isling, et al.
(författare)
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The small and large intestine contain related mesenchymal subsets that derive from embryonic Gli1 + precursors.
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- The intestinal lamina propria contains a diverse network of fibroblasts that provide key support functions to cells within their local environment. Despite this, our understanding of the diversity, location and ontogeny of fibroblasts within and along the length of the intestine remains incomplete. Here we show that the small and large intestinal lamina propria contain similar fibroblast subsets that locate in specific anatomical niches. Nevertheless, we find that the transcriptional profile of similar fibroblast subsets differs markedly between the small intestine and colon suggesting region specific functions. We perform in vivo transplantation and lineage-tracing experiments to demonstrate that adult intestinal fibroblast subsets, smooth muscle cells and pericytes derive from Gli1-expressing precursors present in embryonic day 12.5 intestine. Trajectory analysis of single cell RNA-seq datasets of E12.5 and adult mesenchymal cells suggest that adult smooth muscle cells and fibroblasts derive from distinct embryonic intermediates and that adult fibroblast subsets develop in a linear trajectory from CD81 + fibroblasts. Finally, we provide evidence that colonic subepithelial PDGFRα hi fibroblasts comprise several functionally distinct populations that originate from an Fgfr2-expressing fibroblast intermediate. Our results provide insights into intestinal stromal cell diversity, location, function, and ontogeny, with implications for intestinal development and homeostasis.
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| 5. |
- van Hooren, Luuk
(författare)
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Antibody-based immunotherapy of cancer : From optimization to novel approaches
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Antibody immunotherapy is a successful therapeutic approach to treat cancer. The overall aim of this thesis is to investigate the mechanisms of antibody-based immunotherapies and the role of the tumor microenvironment in mediating the anti-tumor immune response, in order to aid the development of improved immunotherapies for cancer patients.Agonistic CD40 antibodies activate dendritic cells and improve anti-tumor T-cell responses. In Paper I we demonstrate that their efficacy can be enhanced by co-treatment with sunitinib, a multi-targeted tyrosine kinase inhibitor. The combination therapy restrains immunosuppression, synergistically increases endothelial activation and improves tumor T-cell recruitment, resulting in restrained tumor growth and prolonged survival. CTLA-4 and PD-1 negatively regulate the anti-tumor T-cell response and blocking these immune checkpoints with antibodies enhances anti-tumor immunity. However, CTLA-4 checkpoint blockade is associated with severe adverse events. In Paper II, a local low-dose administration of CTLA-4 antibodies is demonstrated to be equally effective as systemic administration in treating experimental bladder cancer. Importantly, antibody spread is reduced, indicating that local administration may be an effective strategy to reduce side effects associated with CTLA-4 blockade.Tumor-derived expression of Galectin-1 enhances angiogenesis and suppresses anti-tumor immunity. In Paper III, endogenous antibodies are induced against Gal-1 using TRX-Gal-1 fusion proteins to break self-tolerance. Vaccination induces anti-Gal-1 endogenous antibodies, resulting in improved vessel perfusion, improved immune-cell infiltration and decreased tumor growth.Immunotherapy for glioma is constrained by the immunosuppressive microenvironment. In Paper IV we demonstrate that in vivo activation of B cells enhances tertiary lymphoid structure formation in the brain. Mice with induced tertiary lymphoid structures have an increase of B cells with a regulatory phenotype and CD8+ T-cell activation is suppressed. The response to PD-1 checkpoint blockade is also inhibited, suggesting tertiary lymphoid structures impair the response to immunotherapy.This thesis demonstrates that immunotherapy can be improved by the addition of anti-angiogenic drugs and that local administration of antibodies is a feasible alternative to the systemic administration conventionally used in the clinic. In addition, therapeutic vaccination and induction of tertiary lymphoid structures by agonistic CD40 antibodies are novel approaches to employ antibodies to modulate the anti-tumor immune response.
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| 6. |
- Xiang, Menglan, et al.
(författare)
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A Single-Cell Transcriptional Roadmap of the Mouse and Human Lymph Node Lymphatic Vasculature
- 2020
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Ingår i: Frontiers in Cardiovascular Medicine. - : FRONTIERS MEDIA SA. - 2297-055X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Single-cell transcriptomics promise to revolutionize our understanding of the vasculature. Emerging computational methods applied to high-dimensional single-cell data allow integration of results between samples and species and illuminate the diversity and underlying developmental and architectural organization of cell populations. Here, we illustrate these methods in the analysis of mouse lymph node (LN) lymphatic endothelial cells (LEC) at single-cell resolution. Clustering identifies five well-delineated subsets, including two medullary sinus subsets not previously recognized as distinct. Nearest neighbor alignments in trajectory space position the major subsets in a sequence that recapitulates the known features and suggests novel features of LN lymphatic organization, providing a transcriptional map of the lymphatic endothelial niches and of the transitions between them. Differences in gene expression reveal specialized programs for (1) subcapsular ceiling endothelial interactions with the capsule connective tissue and cells; (2) subcapsular floor regulation of lymph borne cell entry into the LN parenchyma and antigen presentation; and (3) pathogen interactions and (4) LN remodeling in distinct medullary subsets. LEC of the subcapsular sinus floor and medulla, which represent major sites of cell entry and exit from the LN parenchyma respectively, respond robustly to oxazolone inflammation challenge with enriched signaling pathways that converge on both innate and adaptive immune responses. Integration of mouse and human single-cell profiles reveals a conserved cross-species pattern of lymphatic vascular niches and gene expression, as well as specialized human subsets and genes unique to each species. The examples provided demonstrate the power of single-cell analysis in elucidating endothelial cell heterogeneity, vascular organization, and endothelial cell responses. We discuss the findings from the perspective of LEC functions in relation to niche formations in the unique stromal and highly immunological environment of the LN.
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