ORCID Profile
0000-0003-2856-9410
Current Organisation
University of Oxford
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 09-2016
Publisher: The Royal Society
Date: 05-06-2019
Abstract: In both cells and animals, cannibalism can transfer harmful substances from the consumed to the consumer. Macrophages are immune cells that consume their own dead via a process called cannibalistic efferocytosis. Macrophages that contain harmful substances are found at sites of chronic inflammation, yet the role of cannibalism in this context remains unexplored. Here we take mathematical and experimental approaches to study the relationship between cannibalistic efferocytosis and substance accumulation in macrophages. Through mathematical modelling, we deduce that substances which transfer between in iduals through cannibalism will concentrate inside the population via a coalescence process. This prediction was confirmed for macrophage populations inside a closed system. We used image analysis of whole slide photomicrographs to measure both latex microbead and neutral lipid accumulation inside murine bone marrow-derived macrophages (10 4 – 10 5 cells ) following their stimulation into an inflammatory state ex vivo . While the total number of phagocytosed beads remained constant, cell death reduced cell numbers and efferocytosis concentrated the beads among the surviving macrophages. As lipids are also conserved during efferocytosis, these cells accumulated lipid derived from the membranes of dead and consumed macrophages (becoming macrophage foam cells). Consequently, enhanced macrophage cell death increased the rate and extent of foam cell formation. Our results demonstrate that cannibalistic efferocytosis perpetuates exogenous (e.g. beads) and endogenous (e.g. lipids) substance accumulation inside macrophage populations. As such, cannibalism has similar detrimental consequences in both cells and animals.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 18-11-2003
DOI: 10.1161/01.CIR.0000097119.57756.EF
Abstract: Background— Chemokines are important mediators of inflammatory cell recruitment that play a significant role in atherosclerosis. Fractalkine (CX 3 CL1) is an unusual membrane-bound chemokine that mediates chemotaxis through the CX 3 CR1 receptor. Recently, functional polymorphisms in the human CX3CR1 gene have been described that are associated with coronary artery disease. Methods and Results— We investigated the expression of the CX 3 C chemokine fractalkine and its receptor CX 3 CR1 in human coronary artery plaques by immunocytometry. We show that a subset of mononuclear cells expresses high levels of fractalkine in human coronary atherosclerotic plaques and that smooth muscle cells within the neointima express the fractalkine receptor CX 3 CR1. There is a positive correlation between the number of fractalkine-expressing cells and the number of CX 3 CR1-positive cells in human atherosclerotic plaques ( r =0.70, n=15 plaques). Furthermore, we demonstrate that cultured vascular smooth muscle cells express the CX 3 CR1 receptor and undergo chemotaxis to fractalkine that can be inhibited by G protein inactivation by pertussis toxin. Conclusions— These results suggest that in human atherosclerosis, fractalkine, rather than mediating inflammatory cell recruitment, can act as a mediator of smooth muscle cell migration.
Publisher: American Society of Hematology
Date: 21-02-2013
DOI: 10.1182/BLOOD-2012-08-449181
Abstract: Erythropoiesis must be tightly balanced to guarantee adequate oxygen delivery to all tissues in the body. This process relies predominantly on the hormone erythropoietin (EPO) and its transcription factor hypoxia inducible factor (HIF). Accumulating evidence suggests that oxygen-sensitive prolyl hydroxylases (PHDs) are important regulators of this entire system. Here, we describe a novel mouse line with conditional PHD2 inactivation (cKO P2) in renal EPO producing cells, neurons, and astrocytes that displayed excessive erythrocytosis because of severe overproduction of EPO, exclusively driven by HIF-2α. In contrast, HIF-1α served as a protective factor, ensuring survival of cKO P2 mice with HCT values up to 86%. Using different genetic approaches, we show that simultaneous inactivation of PHD2 and HIF-1α resulted in a drastic PHD3 reduction with consequent overexpression of HIF-2α-related genes, neurodegeneration, and lethality. Taken together, our results demonstrate for the first time that conditional loss of PHD2 in mice leads to HIF-2α–dependent erythrocytosis, whereas HIF-1α protects these mice, providing a platform for developing new treatments of EPO-related disorders, such as anemia.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 29-01-2008
Abstract: The Duffy antigen/receptor for chemokines (DARC) is an unusual chemokine receptor that binds a large number of inflammatory chemokines of both the CC and CXC families with nanomolar affinity, yet it lacks the ability to signal upon ligand binding. Using bioluminescent resonant energy transfer, we have demonstrated for the first time that DARC exists as a constitutive homo-oligomer in living cells and furthermore that DARC hetero-oligomerizes with the CC chemokine receptor CCR5. DARC-CCR5 interaction impairs chemotaxis and calcium flux through CCR5, whereas internalization of CCR5 in response to ligand binding remains unchanged. These results suggest a novel mechanism by which DARC could modulate inflammatory responses to chemokines in vivo.
Publisher: Springer Science and Business Media LLC
Date: 18-03-2015
DOI: 10.1038/NCOMMS7614
Abstract: Chemokine signalling drives monocyte recruitment in atherosclerosis and aortic aneurysms. The mechanisms that lead to retention and accumulation of macrophages in the vascular wall remain unclear. Regulator of G-Protein Signalling-1 (RGS1) deactivates G-protein signalling, reducing the response to sustained chemokine stimulation. Here we show that Rgs1 is upregulated in atherosclerotic plaque and aortic aneurysms. Rgs1 reduces macrophage chemotaxis and desensitizes chemokine receptor signalling. In early atherosclerotic lesions, Rgs1 regulates macrophage accumulation and is required for the formation and rupture of Angiotensin II-induced aortic aneurysms, through effects on leukocyte retention. Collectively, these data reveal a role for Rgs1 in leukocyte trafficking and vascular inflammation and identify Rgs1 , and inhibition of chemokine receptor signalling as potential therapeutic targets in vascular disease.
Publisher: Wiley
Date: 04-09-2015
DOI: 10.1002/GLIA.22906
Publisher: Wiley
Date: 12-2003
DOI: 10.1111/J.0959-9673.2003.00365.X
Abstract: Classic studies of tuberculosis (TB) revealed morphologic evidence of considerable heterogeneity of macrophages (MØs), but the functional significance of this heterogeneity remains unknown. We have used newly available specific antibodies for selected membrane and secretory molecules to examine the phenotype of MØs in situ in a range of South African patients with TB, compared with sarcoidosis. Patients were human immunodeficiency virus-negative adults and children, and the examined biopsy specimens included lung and lymph nodes. Mature pulmonary MØs (alveolar, interstitial, epithelioid and multinucleated giant cells) selectively expressed scavenger receptor type A and a novel carboxypeptidase-like antigen called carboxypeptidase-related vitellogenin-like MØ molecule (CPVL). CPVL did not display enhanced expression in sarcoidosis, vs. TB patients, as observed with angiotensin-converting enzyme (ACE), a related molecule. Immunocytochemical studies with surfactant proteins (SP)-A and -D showed that type II alveolar cells expressed these collectins, as did MØs, possibly after binding of secreted proteins. Studies with an antibody specific for the C-terminus of fractalkine, a tethered CX3C chemokine, confirmed synthesis of this molecule by bronchiolar epithelial cells and occasional endothelial cells. These studies provide new marker antigens and extend previous studies on MØ differentiation, activation and local interactions in chronic human granulomatous inflammation in the lung.
Publisher: Cambridge University Press (CUP)
Date: 05-11-2001
DOI: 10.1017/S1462399401003696
Abstract: Atherosclerosis is a pathological process that takes place in the major arteries and is the underlying cause of heart attacks, stroke and peripheral artery disease. The earliest detectable lesions, called fatty streaks, contain macrophage foam cells that are derived from recruited monocytes. More-advanced atherosclerotic lesions, called fibro-fatty plaques, are the result of continued monocyte recruitment and smooth muscle cell migration and proliferation. Variable numbers of CD4 + T cells are found in atherosclerotic lesions, and cytokines secreted by T helper 1 (Th1)- or Th2-type cells can have a profound influence on macrophage gene expression within atherosclerotic plaques. This review briefly addresses the key features of macrophage biology and discusses the factors that influence the growth and development of atherosclerotic lesions (atherogenesis). It then considers the potential role of chemokines in mediating monocyte recruitment and macrophage differentiation within atherosclerotic lesions.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for David Greaves.