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Bradford BM, McGuire LI, Hume DA, Pridans C, Mabbott NA. Microglia deficiency accelerates prion disease but does not enhance prion accumulation in the brain. Glia 2022; 70:2169-2187. [PMID: 35852018 PMCID: PMC9544114 DOI: 10.1002/glia.24244] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/24/2022] [Accepted: 06/30/2022] [Indexed: 01/08/2023]
Abstract
Prion diseases are transmissible, neurodegenerative disorders associated with misfolding of the prion protein. Previous studies show that reduction of microglia accelerates central nervous system (CNS) prion disease and increases the accumulation of prions in the brain, suggesting that microglia provide neuroprotection by phagocytosing and destroying prions. In Csf1rΔFIRE mice, the deletion of an enhancer within Csf1r specifically blocks microglia development, however, their brains develop normally and show none of the deficits reported in other microglia-deficient models. Csf1rΔFIRE mice were used as a refined model in which to study the impact of microglia-deficiency on CNS prion disease. Although Csf1rΔFIRE mice succumbed to CNS prion disease much earlier than wild-type mice, the accumulation of prions in their brains was reduced. Instead, astrocytes displayed earlier, non-polarized reactive activation with enhanced phagocytosis of neuronal contents and unfolded protein responses. Our data suggest that rather than simply phagocytosing and destroying prions, the microglia instead provide host-protection during CNS prion disease and restrict the harmful activities of reactive astrocytes.
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Affiliation(s)
- Barry M. Bradford
- The Roslin Institute and R(D)SVSUniversity of Edinburgh, Easter Bush CampusMidlothianUK
| | - Lynne I. McGuire
- The Roslin Institute and R(D)SVSUniversity of Edinburgh, Easter Bush CampusMidlothianUK
| | - David A. Hume
- Mater Research Institute‐University of Queensland, Translational Research InstituteWoolloongabbaQueenslandAustralia
| | - Clare Pridans
- Simons Initiative for the Developing Brain, Centre for Discovery Brain SciencesUniversity of Edinburgh, Hugh Robson BuildingEdinburghUK
- Centre for Inflammation ResearchThe Queen's Medical Research Institute, Edinburgh BioQuarterEdinburghUK
| | - Neil A. Mabbott
- The Roslin Institute and R(D)SVSUniversity of Edinburgh, Easter Bush CampusMidlothianUK
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2
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Abstract
Prion diseases such as Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy in cattle, and scrapie in sheep, are infectious and chronic neurodegenerative diseases to which there are no cures. Infection with prions in the central nervous system (CNS) ultimately causes extensive neurodegeneration, and this is accompanied by prominent microglial and astrocytic activation in affected regions. The microglia are the CNS macrophages and help maintain neuronal homeostasis, clear dead or dying cells and provide defense against pathogens. The microglia also provide neuroprotection during CNS prion disease, but their pro-inflammatory activation may exacerbate the development of the neuropathology. Innate immune tolerance induced by consecutive systemic bacterial lipopolysaccharide (LPS) treatment can induce long-term epigenetic changes in the microglia in the brain that several months later can dampen their responsiveness to subsequent LPS treatment and impede the development of neuritic damage in a transgenic mouse model of Alzheimer’s disease-like pathology. We therefore reasoned that innate immune tolerance in microglia might similarly impede the subsequent development of CNS prion disease. To test this hypothesis groups of mice were first infected with prions by intracerebral injection, and 35 days later given four consecutive systemic injections with LPS to induce innate immune tolerance. Our data show that consecutive systemic LPS treatment did not affect the subsequent development of CNS prion disease. Our data suggests innate immune tolerance in microglia does not influence the subsequent onset of prion disease-induced neuropathology in mice, despite previously published evidence of this effect in an Alzheimer’s disease mouse model.
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Munro DAD, Bradford BM, Mariani SA, Hampton DW, Vink CS, Chandran S, Hume DA, Pridans C, Priller J. CNS macrophages differentially rely on an intronic Csf1r enhancer for their development. Development 2020; 147:147/23/dev194449. [PMID: 33323375 PMCID: PMC7758622 DOI: 10.1242/dev.194449] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/26/2020] [Indexed: 12/29/2022]
Abstract
The central nervous system hosts parenchymal macrophages, known as microglia, and non-parenchymal macrophages, collectively termed border-associated macrophages (BAMs). Microglia, but not BAMs, were reported to be absent in mice lacking a conserved Csf1r enhancer: the fms-intronic regulatory element (FIRE). However, it is unknown whether FIRE deficiency also impacts BAM arrival and/or maintenance. Here, we show that macrophages in the ventricular system of the brain, including Kolmer's epiplexus macrophages, are absent in Csf1rΔFIRE/ΔFIRE mice. Stromal choroid plexus BAMs are also considerably reduced. During normal development, we demonstrate that intracerebroventricular macrophages arrive from embryonic day 10.5, and can traverse ventricular walls in embryonic slice cultures. In Csf1rΔFIRE/ΔFIRE embryos, the arrival of both primitive microglia and intracerebroventricular macrophages was eliminated, whereas the arrival of cephalic mesenchyme and stromal choroid plexus BAMs was only partially restricted. Our results provide new insights into the development and regulation of different CNS macrophage populations. Summary: Deletion of the fms-intronic regulatory element of Csf1r in mouse disrupts the engraftment and maintenance of central nervous system macrophages in a compartment-specific manner.
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Affiliation(s)
- David A D Munro
- UK Dementia Research Institute at The University of Edinburgh, Chancellor's Building, Edinburgh EH16 4SB, UK
| | - Barry M Bradford
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, The University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Samanta A Mariani
- Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - David W Hampton
- Euan MacDonald Centre for MND Research, The University of Edinburgh, Edinburgh EH16 4SB, UK.,Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Chris S Vink
- Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Siddharthan Chandran
- UK Dementia Research Institute at The University of Edinburgh, Chancellor's Building, Edinburgh EH16 4SB, UK.,Euan MacDonald Centre for MND Research, The University of Edinburgh, Edinburgh EH16 4SB, UK.,Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh EH16 4SB, UK.,Anne Rowling Regenerative Neurology Clinic, The University of Edinburgh, Edinburgh EH16 4SB, UK
| | - David A Hume
- Mater Research Institute, University of Queensland, Translational Research Institute, Woolloongabba Q4102, Australia
| | - Clare Pridans
- The University of Edinburgh Centre for Inflammation Research, The Queen's Medical Research Institute, Edinburgh BioQuarter, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.,Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - Josef Priller
- UK Dementia Research Institute at The University of Edinburgh, Chancellor's Building, Edinburgh EH16 4SB, UK .,Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh EH16 4SB, UK.,Department of Neuropsychiatry and Laboratory of Molecular Psychiatry, Charité - Universitätsmedizin Berlin, 10117 Berlin, Germany
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4
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Mabbott NA, Bradford BM, Pal R, Young R, Donaldson DS. The Effects of Immune System Modulation on Prion Disease Susceptibility and Pathogenesis. Int J Mol Sci 2020; 21:E7299. [PMID: 33023255 PMCID: PMC7582561 DOI: 10.3390/ijms21197299] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 09/25/2020] [Accepted: 09/29/2020] [Indexed: 12/17/2022] Open
Abstract
Prion diseases are a unique group of infectious chronic neurodegenerative disorders to which there are no cures. Although prion infections do not stimulate adaptive immune responses in infected individuals, the actions of certain immune cell populations can have a significant impact on disease pathogenesis. After infection, the targeting of peripherally-acquired prions to specific immune cells in the secondary lymphoid organs (SLO), such as the lymph nodes and spleen, is essential for the efficient transmission of disease to the brain. Once the prions reach the brain, interactions with other immune cell populations can provide either host protection or accelerate the neurodegeneration. In this review, we provide a detailed account of how factors such as inflammation, ageing and pathogen co-infection can affect prion disease pathogenesis and susceptibility. For example, we discuss how changes to the abundance, function and activation status of specific immune cell populations can affect the transmission of prion diseases by peripheral routes. We also describe how the effects of systemic inflammation on certain glial cell subsets in the brains of infected individuals can accelerate the neurodegeneration. A detailed understanding of the factors that affect prion disease transmission and pathogenesis is essential for the development of novel intervention strategies.
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Affiliation(s)
- Neil A. Mabbott
- The Roslin Institute & Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK; (B.M.B.); (R.P.); (R.Y.); (D.S.D.)
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5
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Alterauge D, Bagnoli JW, Dahlström F, Bradford BM, Mabbott NA, Buch T, Enard W, Baumjohann D. Continued Bcl6 Expression Prevents the Transdifferentiation of Established Tfh Cells into Th1 Cells during Acute Viral Infection. Cell Rep 2020; 33:108232. [PMID: 33027650 DOI: 10.1016/j.celrep.2020.108232] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 07/01/2020] [Accepted: 09/15/2020] [Indexed: 12/29/2022] Open
Abstract
T follicular helper (Tfh) cells are crucial for the establishment of germinal centers (GCs) and potent antibody responses. Nevertheless, the T cell-intrinsic factors that are required for the maintenance of already-established Tfh cells and GCs remain largely unknown. Here, we use temporally guided gene ablation in CD4+ T cells to dissect the contributions of the Tfh-associated chemokine receptor CXCR5 and the transcription factor Bcl6. Induced ablation of Cxcr5 has minor effects on the function of established Tfh cells, and Cxcr5-ablated cells still exhibit most of the features of CXCR5+ Tfh cells. In contrast, continued Bcl6 expression is critical to maintain the GC Tfh cell phenotype and also the GC reaction. Importantly, Bcl6 ablation during acute viral infection results in the transdifferentiation of established Tfh into Th1 cells, thus highlighting the plasticity of Tfh cells. These findings have implications for strategies that boost or restrain Tfh cells and GCs in health and disease.
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Affiliation(s)
- Dominik Alterauge
- Institute for Immunology, Biomedical Center, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany
| | - Johannes W Bagnoli
- Anthropology & Human Genomics, Department of Biology II, LMU Munich, Grosshaderner Str. 2, 82152 Planegg-Martinsried, Germany
| | - Frank Dahlström
- Institute for Immunology, Biomedical Center, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany
| | - Barry M Bradford
- The Roslin Institute and the Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Neil A Mabbott
- The Roslin Institute and the Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Thorsten Buch
- Institute of Laboratory Animal Science, University of Zurich, Wagistr. 12, 8952 Schlieren, Switzerland
| | - Wolfgang Enard
- Anthropology & Human Genomics, Department of Biology II, LMU Munich, Grosshaderner Str. 2, 82152 Planegg-Martinsried, Germany
| | - Dirk Baumjohann
- Institute for Immunology, Biomedical Center, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany; Medical Clinic III for Oncology, Hematology, Immuno-Oncology, and Rheumatology, University Hospital Bonn, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany.
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6
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Alfituri OA, Bradford BM, Paxton E, Morrison LJ, Mabbott NA. Influence of the Draining Lymph Nodes and Organized Lymphoid Tissue Microarchitecture on Susceptibility to Intradermal Trypanosoma brucei Infection. Front Immunol 2020; 11:1118. [PMID: 32582198 PMCID: PMC7283954 DOI: 10.3389/fimmu.2020.01118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 05/07/2020] [Indexed: 12/13/2022] Open
Abstract
Infection of the mammalian host with African trypanosomes begins when the tsetse fly vector injects the parasites into the skin dermis during blood feeding. After injection into the skin, trypanosomes first accumulate in the draining lymph node before disseminating systemically. Whether this early accumulation within the draining lymph node is important for the trypanosomes to establish infection was not known. Lymphotoxin-β-deficient mice (LTβ-/- mice) lack most secondary lymphoid tissues, but retain the spleen and mesenteric lymph nodes. These mice were used to test the hypothesis that the establishment of infection after intradermal (ID) T. brucei infection would be impeded in the absence of the skin draining lymph nodes. However, LTβ-/- mice revealed greater susceptibility to ID T. brucei infection than wild-type mice, indicating that the early accumulation of the trypanosomes in the draining lymph nodes was not essential to establish systemic infection. Although LTβ-/- mice were able to control the first parasitemia wave as effectively as wild-type mice, they were unable to control subsequent parasitemia waves. LTβ-/- mice also lack organized B cell follicles and germinal centers within their remaining secondary lymphoid tissues. As a consequence, LTβ-/- mice have impaired immunoglobulin (Ig) isotype class-switching responses. When the disturbed microarchitecture of the B cell follicles in the spleens of LTβ-/- mice was restored by reconstitution with wild-type bone marrow, their susceptibility to ID T. brucei infection was similar to that of wild-type control mice. This effect coincided with the ability to produce significant serum levels of Ig isotype class-switched parasite-specific antibodies. Thus, our data suggest that organized splenic microarchitecture and the production of parasite-specific Ig isotype class-switched antibodies are essential for the control of ID African trypanosome infections.
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Affiliation(s)
- Omar A Alfituri
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Barry M Bradford
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Edith Paxton
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Liam J Morrison
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Neil A Mabbott
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, United Kingdom
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7
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Bradford BM, Mabbott NA. Unaltered intravenous prion disease pathogenesis in the temporary absence of marginal zone B cells. Sci Rep 2019; 9:19119. [PMID: 31836813 PMCID: PMC6910919 DOI: 10.1038/s41598-019-55772-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 12/03/2019] [Indexed: 11/16/2022] Open
Abstract
Prion diseases are a unique, infectious, neurodegenerative disorders that can affect animals and humans. Data from mouse transmissions show that efficient infection of the host after intravenous (IV) prion exposure is dependent upon the early accumulation and amplification of the prions on stromal follicular dendritic cells (FDC) in the B cell follicles. How infectious prions are initially conveyed from the blood-stream to the FDC in the spleen is uncertain. Addressing this issue is important as susceptibility to peripheral prion infections can be reduced by treatments that prevent the early accumulation of prions upon FDC. The marginal zone (MZ) in the spleen contains specialized subsets of B cells and macrophages that are positioned to continuously monitor the blood-stream and remove pathogens, toxins and apoptotic cells. The continual shuttling of MZ B cells between the MZ and the B-cell follicle enables them to efficiently capture and deliver blood-borne antigens and antigen-containing immune complexes to splenic FDC. We tested the hypothesis that MZ B cells also play a role in the initial shuttling of prions from the blood-stream to FDC. MZ B cells were temporarily depleted from the MZ by antibody-mediated blocking of integrin function. We show that depletion of MZ B cells around the time of IV prion exposure did not affect the early accumulation of blood-borne prions upon splenic FDC or reduce susceptibility to IV prion infection. In conclusion, our data suggest that the initial delivery of blood-borne prions to FDC in the spleen occurs independently of MZ B cells.
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Affiliation(s)
- Barry M Bradford
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush, EH25 9RG, UK
| | - Neil A Mabbott
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush, EH25 9RG, UK.
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8
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Bradford BM, Wijaya CAW, Mabbott NA. Discrimination of Prion Strain Targeting in the Central Nervous System via Reactive Astrocyte Heterogeneity in CD44 Expression. Front Cell Neurosci 2019; 13:411. [PMID: 31551718 PMCID: PMC6746926 DOI: 10.3389/fncel.2019.00411] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 08/26/2019] [Indexed: 01/15/2023] Open
Abstract
Prion diseases or transmissible spongiform encephalopathies are fatal, progressive, neurodegenerative, protein-misfolding disorders. Prion diseases may arise spontaneously, be inherited genetically or be acquired by infection and affect a variety of mammalian species including humans. Prion infections in the central nervous system (CNS) cause extensive neuropathology, including abnormal accumulations of misfolded host prion protein, vacuolar change resulting in sponge-like (spongiform) appearance of CNS tissue, neurodegeneration and reactive glial responses. Many different prion agent strains exist and these can differ based on disease duration, clinical signs and the targeting and distribution of the neuropathology in distinct brain areas. Reactive astrocytes are a prominent feature in the prion disease affected CNS as revealed by distinct morphological changes and upregulation of glial fibrillary acidic protein (GFAP). The CD44 antigen is a transmembrane glycoprotein involved in cell-cell interactions, cell adhesion and migration. Here we show that CD44 is also highly expressed in a subset of reactive astrocytes in regions of the CNS targeted by prions. Astrocyte heterogeneity revealed by differential CD44 upregulation occurs coincident with the earliest neuropathological changes during the pre-clinical phase of disease, and is not affected by the route of infection. The expression and distribution of CD44 was compared in brains from a large collection of 15 distinct prion agent strains transmitted to mice of different prion protein (Prnp) genotype backgrounds. Our data show that the pattern of CD44 upregulation observed in the hippocampus in each prion agent strain and host Prnp genotype combination was unique. Many mouse-adapted prion strains and hosts have previously been characterized based on the pattern of the distribution of the spongiform pathology or the misfolded PrP deposition within the brain. Our data show that CD44 expression also provides a reliable discriminatory marker of prion infection with a greater dynamic range than misfolded prion protein deposition, aiding strain identification. Together, our data reveal CD44 as a novel marker to detect reactive astrocyte heterogeneity during CNS prion disease and for enhanced identification of distinct prion agent strains.
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Affiliation(s)
- Barry M Bradford
- The Roslin Institute and R(D)SVS, The University of Edinburgh, Edinburgh, United Kingdom
| | - Christianus A W Wijaya
- The Roslin Institute and R(D)SVS, The University of Edinburgh, Edinburgh, United Kingdom
| | - Neil A Mabbott
- The Roslin Institute and R(D)SVS, The University of Edinburgh, Edinburgh, United Kingdom
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9
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Bradford BM, Donaldson DS, Forman R, Else KJ, Mabbott NA. Increased susceptibility to oral Trichuris muris infection in the specific absence of CXCR5 + CD11c + cells. Parasite Immunol 2019; 40:e12566. [PMID: 29920694 PMCID: PMC6099414 DOI: 10.1111/pim.12566] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 06/14/2018] [Indexed: 12/23/2022]
Abstract
Trichuris muris is a natural mouse helminth pathogen which establishes infection specifically in the caecum and proximal colon. The rapid expulsion of T. muris in resistant mouse strains is associated with the induction of a protective T helper cell type 2 (Th2)‐polarized immune response. Susceptible mouse strains, in contrast, mount an inappropriate Th1 response to T. muris infection. Expression of the chemokine CXCL13 by stromal follicular dendritic cells attracts CXCR5‐expressing cells towards the B‐cell follicles. Previous studies using a complex in vivo depletion model have suggested that CXCR5‐expressing conventional dendritic cells (cDC) help regulate the induction of Th2‐polarized responses. Here, transgenic mice with CXCR5 deficiency specifically restricted to CD11c+ cells were used to determine whether the specific absence CXCR5 on CD11c+ cells such as cDC would influence susceptibility to oral T. muris infection by affecting the Th1/Th2 balance. We show that in contrast to control mice, those which lacked CXCR5 expression on CD11c+ cells failed to clear T. muris infection and developed cytokine and antibody responses that suggested a disturbed Th1/Th2 balance with enhanced IFN‐γ expression. These data suggest an important role of CXCR5‐expressing CD11c+ cells such as cDC in immunity to oral T. muris infection.
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Affiliation(s)
- Barry M Bradford
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, UK
| | - David S Donaldson
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, UK
| | - Ruth Forman
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Kathryn J Else
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Neil A Mabbott
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, UK
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10
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Melo-Gonzalez F, Kammoun H, Evren E, Dutton EE, Papadopoulou M, Bradford BM, Tanes C, Fardus-Reid F, Swann JR, Bittinger K, Mabbott NA, Vallance BA, Willinger T, Withers DR, Hepworth MR. Antigen-presenting ILC3 regulate T cell-dependent IgA responses to colonic mucosal bacteria. J Exp Med 2019; 216:728-742. [PMID: 30814299 PMCID: PMC6446868 DOI: 10.1084/jem.20180871] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 12/12/2018] [Accepted: 02/08/2019] [Indexed: 01/05/2023] Open
Abstract
Intestinal immune homeostasis is dependent upon tightly regulated and dynamic host interactions with the commensal microbiota. Immunoglobulin A (IgA) produced by mucosal B cells dictates the composition of commensal bacteria residing within the intestine. While emerging evidence suggests the majority of IgA is produced innately and may be polyreactive, mucosal-dwelling species can also elicit IgA via T cell-dependent mechanisms. However, the mechanisms that modulate the magnitude and quality of T cell-dependent IgA responses remain incompletely understood. Here we demonstrate that group 3 innate lymphoid cells (ILC3) regulate steady state interactions between T follicular helper cells (TfH) and B cells to limit mucosal IgA responses. ILC3 used conserved migratory cues to establish residence within the interfollicular regions of the intestinal draining lymph nodes, where they act to limit TfH responses and B cell class switching through antigen presentation. The absence of ILC3-intrinsic antigen presentation resulted in increased and selective IgA coating of bacteria residing within the colonic mucosa. Together these findings implicate lymph node resident, antigen-presenting ILC3 as a critical regulatory checkpoint in the generation of T cell-dependent colonic IgA and suggest ILC3 act to maintain tissue homeostasis and mutualism with the mucosal-dwelling commensal microbiota.
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Affiliation(s)
- Felipe Melo-Gonzalez
- Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, UK.,Manchester Collaborative Centre for Inflammation Research, Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Hana Kammoun
- Center for Infectious Medicine, Department of Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Elza Evren
- Center for Infectious Medicine, Department of Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Emma E Dutton
- Institute of Immunology and Immunotherapy (III), College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Markella Papadopoulou
- Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, UK.,Manchester Collaborative Centre for Inflammation Research, Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Barry M Bradford
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush, UK
| | - Ceylan Tanes
- Division of Gastroenterology, Hepatology, and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Fahmina Fardus-Reid
- Division of Integrative Systems Medicine and Digestive Diseases, Imperial College London, South Kensington, UK
| | - Jonathan R Swann
- Division of Integrative Systems Medicine and Digestive Diseases, Imperial College London, South Kensington, UK
| | - Kyle Bittinger
- Division of Gastroenterology, Hepatology, and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Neil A Mabbott
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush, UK
| | - Bruce A Vallance
- Department of Pediatrics, British Columbia Children's Hospital, University of British Columbia, Vancouver, Canada
| | - Tim Willinger
- Center for Infectious Medicine, Department of Medicine, Karolinska Institutet, Stockholm, Sweden
| | - David R Withers
- Institute of Immunology and Immunotherapy (III), College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Matthew R Hepworth
- Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, UK .,Manchester Collaborative Centre for Inflammation Research, Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
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11
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Denton AE, Innocentin S, Carr EJ, Bradford BM, Lafouresse F, Mabbott NA, Mörbe U, Ludewig B, Groom JR, Good-Jacobson KL, Linterman MA. Type I interferon induces CXCL13 to support ectopic germinal center formation. J Exp Med 2019; 216:621-637. [PMID: 30723095 PMCID: PMC6400543 DOI: 10.1084/jem.20181216] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 12/05/2018] [Accepted: 01/17/2019] [Indexed: 01/08/2023] Open
Abstract
Denton et al. show that during influenza infection of mice, type I interferon can induce CXCL13 de novo in pulmonary PGDFRα+ fibroblasts. This chemokine drives CXCR5-dependent recruitment of B cells to the lung, thereby supporting pulmonary germinal center formation. Ectopic lymphoid structures form in a wide range of inflammatory conditions, including infection, autoimmune disease, and cancer. In the context of infection, this response can be beneficial for the host: influenza A virus infection–induced pulmonary ectopic germinal centers give rise to more broadly cross-reactive antibody responses, thereby generating cross-strain protection. However, despite the ubiquity of ectopic lymphoid structures and their role in both health and disease, little is known about the mechanisms by which inflammation is able to convert a peripheral tissue into one that resembles a secondary lymphoid organ. Here, we show that type I IFN produced after viral infection can induce CXCL13 expression in a phenotypically distinct population of lung fibroblasts, driving CXCR5-dependent recruitment of B cells and initiating ectopic germinal center formation. This identifies type I IFN as a novel inducer of CXCL13, which, in combination with other stimuli, can promote lung remodeling, converting a nonlymphoid tissue into one permissive to functional tertiary lymphoid structure formation.
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Affiliation(s)
- Alice E Denton
- Laboratory of Lymphocyte Signalling and Development, Babraham Institute, Cambridge, UK
| | - Silvia Innocentin
- Laboratory of Lymphocyte Signalling and Development, Babraham Institute, Cambridge, UK
| | - Edward J Carr
- Laboratory of Lymphocyte Signalling and Development, Babraham Institute, Cambridge, UK.,Department of Medicine, University of Cambridge, Cambridge, UK
| | - Barry M Bradford
- The Roslin Institute and the Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, UK
| | - Fanny Lafouresse
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Neil A Mabbott
- The Roslin Institute and the Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, UK
| | - Urs Mörbe
- Institute of Immunobiology, Kantonsspital St. Gallen, St. Gallen, Switzerland
| | - Burkhard Ludewig
- Institute of Immunobiology, Kantonsspital St. Gallen, St. Gallen, Switzerland
| | - Joanna R Groom
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Kim L Good-Jacobson
- Infection and Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.,Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Michelle A Linterman
- Laboratory of Lymphocyte Signalling and Development, Babraham Institute, Cambridge, UK
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12
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Abstract
Prion diseases are a unique group of transmissible, typically sub-acute, neurodegenerative disorders. During central nervous system (CNS) prion disease, the microglia become activated and are thought to provide a protective response by scavenging and clearing prions. The mammalian intestine is host to a large burden of commensal micro-organisms, especially bacteria, termed the microbiota. The commensal microbiota has beneficial effects on host health, including through the metabolism of essential nutrients, regulation of host development and protection against pathogens. The commensal gut microbiota also constitutively regulates the functional maturation of microglia in the CNS, and microglial function is impaired when it is absent in germ-free mice. In the current study, we determined whether the absence of the commensal gut microbiota might also affect prion disease pathogenesis. Our data clearly show that the absence of the commensal microbiota in germ-free mice did not affect prion disease duration or susceptibility after exposure to prions by intraperitoneal or intracerebral injection. Furthermore, the magnitude and distribution of the characteristic neuropathological hallmarks of terminal prion disease in the CNS, including the development of spongiform pathology, accumulation of prion disease-specific protein (PrP), astrogliosis and microglial activation, were similar in conventionally housed and germ-free mice. Thus, although the commensal gut microbiota constitutively promotes the maintenance of the microglia in the CNS under steady-state conditions in naïve mice, our data suggest that dramatic changes to the abundance or complexity of the commensal gut microbiota are unlikely to influence CNS prion disease pathogenesis.
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Affiliation(s)
- Barry M Bradford
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush EH25 9RG, UK
| | - Laura Tetlow
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush EH25 9RG, UK
| | - Neil A Mabbott
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush EH25 9RG, UK
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13
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Donaldson DS, Bradford BM, Artis D, Mabbott NA. Reciprocal regulation of lymphoid tissue development in the large intestine by IL-25 and IL-23. Mucosal Immunol 2015; 8:582-95. [PMID: 25249168 PMCID: PMC4424384 DOI: 10.1038/mi.2014.90] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 07/29/2014] [Indexed: 02/04/2023]
Abstract
Isolated lymphoid follicles (ILFs) develop after birth in the small and large intestines (SI and LI) and represent a dynamic response of the gut immune system to the microbiota. Despite their similarities, ILF development in the SI and LI differs on a number of levels. We show that unlike ILF in the SI, the microbiota inhibits ILF development in the colon as conventionalization of germ-free mice reduced colonic ILFs. From this, we identified a novel mechanism regulating colonic ILF development through the action of interleukin (IL)-25 on IL-23 and its ability to modulate T regulatory cell (Treg) differentiation. Colonic ILF develop in the absence of a number of factors required for the development of their SI counterparts and can be specifically suppressed by factors other than IL-25. However, IL-23 is the only factor identified that specifically promotes colonic ILFs without affecting SI-ILF development. Both IL-23 and ILFs are associated with inflammatory bowel disease, suggesting that disruption to this pathway may have an important role in the breakdown of microbiota-immune homeostasis.
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Affiliation(s)
- D S Donaldson
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, UK
| | - B M Bradford
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, UK
| | - D Artis
- Department of Microbiology and Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - N A Mabbott
- The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, UK,
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14
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Mabbott NA, Kobayashi A, Sehgal A, Bradford BM, Pattison M, Donaldson DS. Aging and the mucosal immune system in the intestine. Biogerontology 2015; 16:133-45. [PMID: 24705962 DOI: 10.1007/s10522-014-9498-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 03/24/2014] [Indexed: 02/07/2023]
Abstract
Bacterial and viral infections of the gastrointestinal tract are more common in the elderly and represent a major cause of morbidity and mortality. The mucosal immune system provides the first line of defence against pathogens acquired by ingestion and inhalation, but its function is adversely affected in the elderly. This aging-related decline in the immune function is termed immunosenescence and is associated with diminished abilities to generate protective immunity, reduced vaccine efficacy, increased incidence of cancer, inflammation and autoimmunity, and the impaired ability to generate tolerance to harmless antigens. In this review we describe our current understanding of the effects immunosenescence has on the innate and adaptive arms of the mucosal immune system in the intestine. Current estimates suggest that by the year 2050 up to 40% of the UK population will be over 65 years old, bringing with it important health challenges. A thorough understanding of the mechanisms that contribute to the development of immunosenescence is therefore crucial to help identify novel approaches to improve mucosal immunity in the elderly.
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Affiliation(s)
- Neil A Mabbott
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK,
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15
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Bradford BM, Piccardo P, Ironside JW, Mabbott NA. Human prion diseases and the risk of their transmission during anatomical dissection. Clin Anat 2014; 27:821-32. [PMID: 24740900 DOI: 10.1002/ca.22403] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 04/01/2014] [Indexed: 01/09/2023]
Abstract
Prion diseases (or transmissible spongiform encephalopathies) are a unique group of fatal progressive neurodegenerative diseases of the central nervous system. The infectious agent is hypothesized to consist solely of a highly protease-resistant misfolded isoform of the host prion protein. Prions display a remarkable degree of resistance to chemical and physical decontamination. Many common forms of decontamination or neutralization used in infection control are ineffective against prions, except chaotropic agents that specifically disrupt proteins. Human cadaveric prosection or dissection for the purposes of teaching and demonstration of human anatomy has a distinguished history and remains one of the fundamentals of medical education. Iatrogenic transmission of human prion diseases has been demonstrated from the inoculation or implantation of human tissues. Therefore, although the incidence of human prion diseases is rare, restrictions exist upon the use of tissues from patients reported with dementia, specifically the brain and other central nervous system material. A current concern is the potential for asymptomatic variant Creutzfeldt-Jakob disease transmission within the UK population. Therefore, despite the preventative measures, the transmission of prion disease through human tissues remains a potential risk to those working with these materials. In this review, we aim to summarize the current knowledge on human prion disease relevant to those working with human tissues in the context of anatomical dissection.
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Affiliation(s)
- Barry M Bradford
- The Roslin Institute and R(D)SVS The University of Edinburgh, Midlothian EH25 9RG, United Kingdom
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16
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Bradford BM, Crocker PR, Mabbott NA. Peripheral prion disease pathogenesis is unaltered in the absence of sialoadhesin (Siglec-1/CD169). Immunology 2014; 143:120-9. [PMID: 24684244 PMCID: PMC4137961 DOI: 10.1111/imm.12294] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 03/18/2014] [Accepted: 03/24/2014] [Indexed: 01/09/2023] Open
Abstract
Prions are a unique group of pathogens, which are considered to comprise solely of an abnormally folded isoform of the cellular prion protein. The accumulation and replication of prions within secondary lymphoid organs is important for their efficient spread from the periphery to the brain where they ultimately cause neurodegeneration and death. Mononuclear phagocytes (MNP) play key roles in prion disease pathogenesis. Some MNP appear to facilitate the propagation of prions to and within lymphoid tissues, whereas others may aid their clearance by phagocytosis and by destroying them. Our recent data show that an intact splenic marginal zone is important for the efficient delivery of prions into the B-cell follicles where they subsequently replicate upon follicular dendritic cells before infecting the nervous system. Sialoadhesin is an MNP-restricted cell adhesion molecule that binds sialylated glycoproteins. Sialoadhesin is constitutively expressed upon splenic marginal zone metallophilic and lymph node sub-capsular sinus macrophage populations, where it may function to bind sialylated glycoproteins, pathogens and exosomes in the blood and lymph via recognition of terminal sialic acid residues. As the prion glycoprotein is highly sialylated, we tested the hypothesis that sialoadhesin may influence prion disease pathogenesis. We show that after peripheral exposure, prion pathogenesis was unaltered in sialoadhesin-deficient mice; revealing that lymphoid sequestration of prions is not mediated via sialoadhesin. Hence, although an intact marginal zone is important for the efficient uptake and delivery of prions into the B-cell follicles of the spleen, this is not influenced by sialoadhesin expression by the MNP within it.
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Affiliation(s)
- Barry M Bradford
- The Roslin Institute and R(D)SVS, University of EdinburghMidlothian, UK
| | - Paul R Crocker
- College of Life Sciences, University of DundeeDundee, UK
| | - Neil A Mabbott
- The Roslin Institute and R(D)SVS, University of EdinburghMidlothian, UK,Correspondence: Dr Neil A. Mabbott, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK., , Senior author: Neil A. Mabbott
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17
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Sauter KA, Pridans C, Sehgal A, Tsai YT, Bradford BM, Raza S, Moffat L, Gow DJ, Beard PM, Mabbott NA, Smith LB, Hume DA. Pleiotropic effects of extended blockade of CSF1R signaling in adult mice. J Leukoc Biol 2014; 96:265-74. [PMID: 24652541 PMCID: PMC4378363 DOI: 10.1189/jlb.2a0114-006r] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We investigated the role of CSF1R signaling in adult mice using prolonged treatment with anti-CSF1R antibody. Mutation of the CSF1 gene in the op/op mouse produces numerous developmental abnormalities. Mutation of the CSF1R has an even more penetrant phenotype, including perinatal lethality, because of the existence of a second ligand, IL-34. These effects on development provide limited insight into functions of CSF1R signaling in adult homeostasis. The carcass weight and weight of several organs (spleen, kidney, and liver) were reduced in the treated mice, but overall body weight gain was increased. Despite the complete loss of Kupffer cells, there was no effect on liver gene expression. The treatment ablated OCL, increased bone density and trabecular volume, and prevented the decline in bone mass seen in female mice with age. The op/op mouse has a deficiency in pancreatic β cells and in Paneth cells in the gut wall. Only the latter was reproduced by the antibody treatment and was associated with increased goblet cell number but no change in villus architecture. Male op/op mice are infertile as a result of testosterone insufficiency. Anti-CSF1R treatment ablated interstitial macrophages in the testis, but there was no sustained effect on testosterone or LH. The results indicate an ongoing requirement for CSF1R signaling in macrophage and OCL homeostasis but indicate that most effects of CSF1 and CSF1R mutations are due to effects on development.
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Affiliation(s)
- Kristin A. Sauter
- The Roslin Institute and Royal (Dick) School of Veterinary Studies and
| | - Clare Pridans
- The Roslin Institute and Royal (Dick) School of Veterinary Studies and
| | - Anuj Sehgal
- The Roslin Institute and Royal (Dick) School of Veterinary Studies and
| | - Yi Ting Tsai
- Medical Research Council Centre for Reproductive Health, The Queen's Medical Research Institute, University of Edinburgh, Scotland, United Kingdom
| | - Barry M. Bradford
- The Roslin Institute and Royal (Dick) School of Veterinary Studies and
| | - Sobia Raza
- The Roslin Institute and Royal (Dick) School of Veterinary Studies and
| | - Lindsey Moffat
- The Roslin Institute and Royal (Dick) School of Veterinary Studies and
| | - Deborah J. Gow
- The Roslin Institute and Royal (Dick) School of Veterinary Studies and
| | - Philippa M. Beard
- The Roslin Institute and Royal (Dick) School of Veterinary Studies and
| | - Neil A. Mabbott
- The Roslin Institute and Royal (Dick) School of Veterinary Studies and
| | - Lee B. Smith
- Medical Research Council Centre for Reproductive Health, The Queen's Medical Research Institute, University of Edinburgh, Scotland, United Kingdom
| | - David A. Hume
- The Roslin Institute and Royal (Dick) School of Veterinary Studies and ,Correspondence: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Scotland EH25 9RG, UK. E-mail:
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18
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Abstract
Prion diseases or transmissible spongiform encephalopathies are a unique category of infectious protein-misfolding neurodegenerative disorders. Hypothesized to be caused by misfolding of the cellular prion protein these disorders possess an infectious quality that thrives in immune-competent hosts. While much has been discovered about the routing and critical components involved in the peripheral pathogenesis of these agents there are still many aspects to be discovered. Research into this area has been extensive as it represents a major target for therapeutic intervention within this group of diseases. The main focus of pathological damage in these diseases occurs within the central nervous system. Cells of the innate immune system have been proven to be critical players in the initial pathogenesis of prion disease, and may have a role in the pathological progression of disease. Understanding how prions interact with the host innate immune system may provide us with natural pathways and mechanisms to combat these diseases prior to their neuroinvasive stage. We present here a review of the current knowledge regarding the role of the innate immune system in prion pathogenesis.
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Affiliation(s)
- Barry M Bradford
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, UK.
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McCulloch L, Brown KL, Bradford BM, Hopkins J, Bailey M, Rajewsky K, Manson JC, Mabbott NA. Follicular dendritic cell-specific prion protein (PrP) expression alone is sufficient to sustain prion infection in the spleen. PLoS Pathog 2011; 7:e1002402. [PMID: 22144895 PMCID: PMC3228802 DOI: 10.1371/journal.ppat.1002402] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 10/11/2011] [Indexed: 11/20/2022] Open
Abstract
Prion diseases are characterised by the accumulation of PrPSc, an abnormally folded isoform of the cellular prion protein (PrPC), in affected tissues. Following peripheral exposure high levels of prion-specific PrPSc accumulate first upon follicular dendritic cells (FDC) in lymphoid tissues before spreading to the CNS. Expression of PrPC is mandatory for cells to sustain prion infection and FDC appear to express high levels. However, whether FDC actively replicate prions or simply acquire them from other infected cells is uncertain. In the attempts to-date to establish the role of FDC in prion pathogenesis it was not possible to dissociate the Prnp expression of FDC from that of the nervous system and all other non-haematopoietic lineages. This is important as FDC may simply acquire prions after synthesis by other infected cells. To establish the role of FDC in prion pathogenesis transgenic mice were created in which PrPC expression was specifically “switched on” or “off” only on FDC. We show that PrPC-expression only on FDC is sufficient to sustain prion replication in the spleen. Furthermore, prion replication is blocked in the spleen when PrPC-expression is specifically ablated only on FDC. These data definitively demonstrate that FDC are the essential sites of prion replication in lymphoid tissues. The demonstration that Prnp-ablation only on FDC blocked splenic prion accumulation without apparent consequences for FDC status represents a novel opportunity to prevent neuroinvasion by modulation of PrPC expression on FDC. Prion diseases are infectious neurological disorders and are considered to be caused by an abnormally folded infectious protein termed PrPSc. Soon after infection prions accumulate first upon follicular dendritic cells (FDC) in lymphoid tissues before spreading to the brain where they cause damage to nerve cells. Cells must express the normal cellular prion protein PrPC to become infected with prions. However, whether FDC are infected with prions or simply acquire them from other infected cells is unknown. To establish the role of FDC in prion disease PrPC expression was specifically “switched on” or “off” only on FDC. We show that PrPC-expressing FDC alone are sufficient to sustain prion replication in the spleen. Furthermore, prion replication is blocked in the spleen when PrPC-expression is switched off only on FDC. These data definitively demonstrate that FDC are the essential sites of prion replication in lymphoid tissues.
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Affiliation(s)
- Laura McCulloch
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Midlothian, United Kingdom
| | - Karen L. Brown
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Midlothian, United Kingdom
| | - Barry M. Bradford
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Midlothian, United Kingdom
| | - John Hopkins
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Midlothian, United Kingdom
| | - Mick Bailey
- Division of Veterinary Pathology, Infection and Immunity, School of Clinical Veterinary Science, University of Bristol, Avon, United Kingdom
| | - Klaus Rajewsky
- Program in Cellular and Molecular Medicine, Children's Hospital, and Immune Disease Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jean C. Manson
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Midlothian, United Kingdom
| | - Neil A. Mabbott
- The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Midlothian, United Kingdom
- * E-mail:
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