6 results on '"Gillespie, Matthew T"'
Search Results
2. The mouse NKR-P1B:Clr-b recognition system is a negative regulator of innate immune responses.
- Author
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Rahim MM, Chen P, Mottashed AN, Mahmoud AB, Thomas MJ, Zhu Q, Brooks CG, Kartsogiannis V, Gillespie MT, Carlyle JR, and Makrigiannis AP
- Subjects
- Animals, Blotting, Western, Cells, Cultured, Female, Flow Cytometry, Histocompatibility Antigens Class I immunology, Histocompatibility Antigens Class I metabolism, Ligands, Lymphoma, B-Cell metabolism, Lymphoma, B-Cell pathology, Male, Mice, Mice, Inbred C57BL, Immunity, Innate immunology, Killer Cells, Natural immunology, Lectins, C-Type physiology, Lymphoma, B-Cell immunology, Membrane Proteins physiology, NK Cell Lectin-Like Receptor Subfamily B physiology
- Abstract
NKR-P1B is a homodimeric type II transmembrane C-type lectinlike receptor that inhibits natural killer (NK) cell function upon interaction with its cognate C-type lectin-related ligand, Clr-b. The NKR-P1B:Clr-b interaction represents a major histocompatibility complex class I (MHC-I)-independent missing-self recognition system that monitors cellular Clr-b levels. We have generated NKR-P1B(B6)-deficient (Nkrp1b(-/-)) mice to study the role of NKR-P1B in NK cell development and function in vivo. NK cell inhibition by Clr-b is abolished in Nkrp1b(-/-) mice, confirming the inhibitory nature of NKR-P1B(B6). Inhibitory receptors also promote NK cell tolerance and responsiveness to stimulation; hence, NK cells expressing NKR-P1B(B6) and Ly49C/I display augmented responsiveness to activating signals vs NK cells expressing either or none of the receptors. In addition, Nkrp1b(-/-) mice are defective in rejecting cells lacking Clr-b, supporting a role for NKR-P1B(B6) in MHC-I-independent missing-self recognition of Clr-b in vivo. In contrast, MHC-I-dependent missing-self recognition is preserved in Nkrp1b(-/-) mice. Interestingly, spontaneous myc-induced B lymphoma cells may selectively use NKR-P1B:Clr-b interactions to escape immune surveillance by wild-type, but not Nkrp1b(-/-), NK cells. These data provide direct genetic evidence of a role for NKR-P1B in NK cell tolerance and MHC-I-independent missing-self recognition., (© 2015 by The American Society of Hematology.)
- Published
- 2015
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3. Membrane-bound receptor activator of NFκB ligand (RANKL) activity displayed by osteoblasts is differentially regulated by osteolytic factors.
- Author
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Singh PP, van der Kraan AG, Xu J, Gillespie MT, and Quinn JM
- Subjects
- Animals, Biological Assay, Calcitriol pharmacology, Cell Line, Coculture Techniques, Dinoprostone pharmacology, Genes, Reporter, Luciferases genetics, Mice, Mice, Inbred C57BL, NF-kappa B metabolism, Osteoblasts drug effects, Osteolysis chemically induced, Osteoprotegerin metabolism, Promoter Regions, Genetic, RANK Ligand genetics, RANK Ligand pharmacology, Transforming Growth Factor alpha pharmacology, Cell Membrane metabolism, Osteoblasts metabolism, Osteolysis metabolism, RANK Ligand metabolism
- Abstract
Osteoclast formation is central to bone metabolism, occurring when myelomonocytic progenitors are stimulated by membrane-bound receptor activator of NFκB ligand (RANKL) on osteoblasts. Osteolytic hormones induce osteoblast RANKL expression, and reduce production of RANKL decoy receptor osteoprotegerin (OPG). However, rather than RANKL and OPG mRNA or protein levels, to measure hormonally-induced osteoclastogenic stimuli the net RANKL activity at the osteoblast surface needs to be determined. To estimate this we developed a cell reporter approach employing pre-osteoclast RAW264.7 cells transfected with luciferase reporter constructs controlled by NFκB (NFκB-RAW) or NFATc1 (NFAT-RAW)-binding promoter elements. Strong signals were induced in these cells by recombinant RANKL over 24h. When NFκB-RAW cells were co-cultured on osteoblastic cells (primary osteoblasts or Kusa O cells) stimulated by osteolytic factors 1,25(OH)(2) vitamin D(3) (1,25(OH)(2)D(3)) and prostaglandin E(2) (PGE(2)), a strong dose dependent signal in NFκB-RAW cells was induced. These signals were completely blocked by soluble recombinant RANKL receptor, RANK.Fc. This osteoblastic RANKL activity was sustained for 3 days in Kusa O cells; with 1,25(OH)(2)D(3) withdrawal, RANKL-induced signal was still detectable 24 h later. However, conditioned medium from stimulated osteoblasts induced no signal. TGFβ treatment inhibited osteoclast formation supported by 1,25(OH)(2)D(3)-treated Kusa O cells, and likewise blocked RANKL-dependent signals in NFAT-RAW co-cultured with these cells. These data indicate net RANKL stimulus at the osteoblast surface is increased by 1,25(OH)(2)D(3) and PGE(2), and suppressed by TGFβ, in line with their effects on RANKL mRNA levels. These results demonstrate the utility of this simple co-culture-based reporter assay for osteoblast RANKL activity., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2012
- Full Text
- View/download PDF
4. Inflammation-induced bone loss: can it be prevented?
- Author
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Romas E and Gillespie MT
- Subjects
- Arthritis, Rheumatoid physiopathology, Bone Resorption etiology, Diphosphonates therapeutic use, Humans, Inflammation physiopathology, Osteoclasts physiology, T-Lymphocytes physiology, Tumor Necrosis Factor-alpha physiology, Arthritis, Rheumatoid complications, Bone Resorption prevention & control, Osteoporosis etiology, Osteoporosis prevention & control
- Abstract
Inflammatory synovitis induces profound bone loss and OCLs are the instrument of this destruction. TNF blockers have an established role in the prevention of inflammatory bone loss in RA; however, not all patients respond to anti-TNF therapy and side effects may prevent long-term treatment in others. The B-cell--depleting antibody rituximab and the T-cell costimulation blocker abatacept are emerging as major treatment options for patients who are resistant to anti-TNF [96,97]. Proof-of-concept studies demonstrate that targeting RANK-mediated osteoclastogenesis prevents inflammatory bone loss and clinical application has only just begun. The efficacy of RANKL inhibition has been witnessed in trials of Denosumab, and RANKL-neutralizing antibodies are likely to become the treatment of choice for blocking RANKL in RA [77,78]. A major limitation of RANKL antagonism is that it does not treat synovitis. Therefore, anti-RANKL therapy most likely will be used in the context of MTX therapy. There is uncertainty about the possible extraskeletal adverse effects of long-term effects of long-term RANKL blockade. In particular, anti-RANKL therapy could jeopardize dendritic cell function or survival. The demonstrable role of OCLs in inflammation-induced bone loss also invites a reconsideration of the new BPs for bone protection [98]. Studies of ZA in preclinical models indicate that bone protection is comparable to that afforded by OPG. One possible caveat is that intravenous BPs are linked to jaw osteonecrosis [99], although the incidence is confined mainly to intensive treatment in the oncology setting. Although pulsed PTH stimulated bone formation in arthritic models, it has yet to be proven clinically in the context of powerful OCL inhibition with TNF or RANKL antagonists. With strategies that normalize OCL numbers, clinicians are poised to accomplish effective prevention of inflammation-induced bone loss.
- Published
- 2006
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5. Modulation of osteoclast formation.
- Author
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Quinn JM and Gillespie MT
- Subjects
- Cell Differentiation physiology, Gene Expression Regulation physiology, Homeostasis physiology, Macrophages cytology, Macrophages physiology, RANK Ligand, Carrier Proteins metabolism, Cytokines metabolism, Hematopoietic Stem Cells cytology, Hematopoietic Stem Cells physiology, Membrane Glycoproteins metabolism, Osteoclasts cytology, Osteoclasts physiology, Signal Transduction physiology
- Abstract
Osteoclasts are derived following the fusion of precursors of hematopoietic and myelomonocytic origin after appropriate stimulus, such as that afforded by RANKL and M-CSF. Thus the osteoclast can be considered as a specialized type of macrophage, and several of the factors that affect osteoclast formation also have affects upon macrophage differentiation. Inhibitors of osteoclast formation may perturb RANKL or M-CSF signalling or affect other signalling pathways. Several of these inhibitors are discussed with the view of their capacity to influence osteoclast differentiation, but not necessarily their activity.
- Published
- 2005
- Full Text
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6. Osteoprotegerin reduces osteoclast numbers and prevents bone erosion in collagen-induced arthritis.
- Author
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Romas E, Sims NA, Hards DK, Lindsay M, Quinn JW, Ryan PF, Dunstan CR, Martin TJ, and Gillespie MT
- Subjects
- Animals, Arthritis, Experimental genetics, Bone Diseases pathology, Collagen, Osteoclasts drug effects, Osteoclasts pathology, Osteoprotegerin, RANK Ligand, Rats, Receptors, Tumor Necrosis Factor, Time Factors, Transcription, Genetic, Tumor Necrosis Factor-alpha genetics, Arthritis, Experimental pathology, Bone Diseases prevention & control, Carrier Proteins genetics, Glycoproteins genetics, Glycoproteins pharmacology, Membrane Glycoproteins genetics, Osteoclasts cytology, Receptors, Cytoplasmic and Nuclear genetics
- Abstract
Rheumatoid arthritis is characterized by progressive synovial inflammation and joint destruction. While matrix metalloproteinases (MMPs) are implicated in the erosion of unmineralized cartilage, bone destruction involves osteoclasts, the specialized cells that resorb calcified bone matrix. RANK ligand (RANKL) expressed by stromal cells and T cells, and its cognate receptor, RANK, were identified as a critical ligand-receptor pair for osteoclast differentiation and survival. A decoy receptor for RANKL, osteoprotegerin, (OPG) impinges on this system and regulates osteoclast numbers and activity. RANKL is also expressed in collagen-induced arthritis (CIA) in which focal collections of osteoclasts are prominent at sites of bone destruction. To determine the role of RANK signaling events in the effector phase of CIA, we investigated effects of Fc-osteoprotegerin fusion protein (Fc-OPG) in CIA. After induction of CIA in Dark Agouti rats, test animals were treated with or without Fc-OPG (3 mg/kg/day) subcutaneously for 5 days, beginning at the onset of disease. Paraffin-embedded joints were then analyzed histologically and the adjacent bone assessed by histomorphometry. Osteoclasts were identified using TRAP staining and expression of the mRNA for OPG and RANKL was identified by in situ hybridization. The results indicated that short-term Fc-OPG effectively prevented joint destruction, even though it had no impact on the inflammatory aspects of CIA. In arthritic joints, Fc-OPG depleted osteoclast numbers by over 75% and diminished bone erosion scores by over 60%. Although cartilage loss was also reduced by Fc-OPG, the effects on cartilage were less striking than those on bone. In arthritic joints OPG mRNA was highly expressed and co-localized with RANK ligand, and treatment with Fc-OPG did not affect the expression of endogenous RANKL or OPG mRNA. These data demonstrate that short term Fc-OPG treatment has powerful anti-erosive effects, principally on bone, even though synovitis is not affected. These findings indicate the potential utility of disrupting RANK signaling to preserve skeletal integrity in inflammatory arthritis.
- Published
- 2002
- Full Text
- View/download PDF
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