ORCID Profile
0000-0002-9839-5463
Current Organisations
AstraZeneca R&D Cambridge
,
Imperial College London
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Publisher: Elsevier BV
Date: 09-2010
Publisher: Springer Science and Business Media LLC
Date: 25-02-2016
DOI: 10.1038/SREP21785
Abstract: We aimed to develop a quantitative antibody-based near infrared fluorescence (NIRF) approach for the imaging of oxidized LDL in atherosclerosis. LO1, a well- characterized monoclonal autoantibody that reacts with malondialdehyde-conjugated LDL, was labeled with a NIRF dye to yield LO1-750. LO1-750 specifically identified necrotic core in ex vivo human coronary lesions. Injection of LO1-750 into high fat (HF) fed atherosclerotic Ldlr −/− mice led to specific focal localization within the aortic arch and its branches, as detected by fluorescence molecular tomography (FMT) combined with micro-computed tomography (CT). Ex vivo confocal microscopy confirmed LO1-750 subendothelial localization of LO1-750 at sites of atherosclerosis, in the vicinity of macrophages. When compared with a NIRF reporter of MMP activity (MMPSense-645-FAST), both probes produced statistically significant increases in NIRF signal in the Ldlr −/− model in relation to duration of HF diet. Upon withdrawing the HF diet, the reduction in oxLDL accumulation, as demonstrated with LO1-750, was less marked than the effect seen on MMP activity. In the rabbit, in vivo injected LO1-750 localization was successfully imaged ex vivo in aortic lesions with a customised intra-arterial NIRF detection catheter. A partially humanized chimeric LO1-Fab-Cys localized similarly to the parent antibody in murine atheroma showing promise for future translation.
Publisher: Elsevier BV
Date: 05-2009
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2014
DOI: 10.1161/CIRCULATIONAHA.113.007124
Abstract: The relevance of the dissociation of circulating pentameric C-reactive protein (pCRP) to its monomeric subunits (mCRP) is poorly understood. We investigated the role of conformational C-reactive protein changes in vivo. We identified mCRP in inflamed human striated muscle, human atherosclerotic plaque, and infarcted myocardium (rat and human) and its colocalization with inflammatory cells, which suggests a general causal role of mCRP in inflammation. This was confirmed in rat intravital microscopy of lipopolysaccharide-induced cremasteric muscle inflammation. Intravenous pCRP administration significantly enhanced leukocyte rolling, adhesion, and transmigration via localized dissociation to mCRP in inflamed but not noninflamed cremaster muscle. This was confirmed in a rat model of myocardial infarction. Mechanistically, this process was dependent on exposure of lysophosphatidylcholine on activated cell membranes, which is generated after phospholipase A2 activation. These membrane changes could be visualized intravitally on endothelial cells, as could the colocalized mCRP generation. Blocking of phospholipase A2 abrogated C-reactive protein dissociation and thereby blunted the proinflammatory effects of C-reactive protein. Identifying the dissociation process as a therapeutic target, we stabilized pCRP using 1,6-bis(phosphocholine)-hexane, which prevented dissociation in vitro and in vivo and consequently inhibited the generation and proinflammatory activity of mCRP notably, it also inhibited mCRP deposition and inflammation in rat myocardial infarction. These results provide in vivo evidence for a novel mechanism that localizes and aggravates inflammation via phospholipase A2–dependent dissociation of circulating pCRP to mCRP. mCRP is proposed as a pathogenic factor in atherosclerosis and myocardial infarction. Most importantly, the inhibition of pCRP dissociation represents a promising, novel anti-inflammatory therapeutic strategy.
Publisher: eLife Sciences Publications, Ltd
Date: 24-11-2020
Publisher: Oxford University Press (OUP)
Date: 05-2014
DOI: 10.1093/NDT/GFU168
Publisher: Springer Science and Business Media LLC
Date: 12-2005
DOI: 10.1007/S00011-005-1382-5
Abstract: C-Reactive protein (CRP) can modulate integrin surface expression on monocytes following Fcgamma receptor engagement. We have investigated the signal transduction events causing this phenotypic alteration. CRP-induced signalling events were examined in THP-1 and primary monocytes, measuring Syk phosphorylation by Western blotting, intracellular Ca(2+) ([Ca(2+)](i)) by Indo-1 fluorescence and surface expression of CD11b by flow cytometry. Cytosolic peroxides were determined by DCF fluorescence. CRP induced phosphorylation of Syk and an increase in [Ca(2+)](i) both of which were inhibitable by the Syk specific antagonist, piceatannol. Piceatannol also inhibited the CRP-induced increase in surface CD11b. In addition, pre-treatment of primary monoytes with the Ca(2+) mobiliser, thapsigargin, increased CD11b expression this effect was accentuated in the presence of CRP but was abolished in the presence of the [Ca(2+)](i) chelator, BAPTA. CRP also increased cytosolic peroxide levels this effect was attenuated by antioxidants (ascorbate, alpha-tocopherol), expression of surface CD11b not being inhibited by antioxidants alone. CRP induces CD11b expression in monocytes through a peroxide independent pathway involving both Syk phosphorylation and [Ca(2+)](i) release.
Publisher: BMJ
Date: 31-05-2014
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2014
DOI: 10.1161/ATVBAHA.114.304172
Abstract: Patients with chronic kidney disease (CKD) display impaired cholesterol efflux capacity and elevated CD14 ++ CD16 + monocyte counts. In mice, dysfunctional cholesterol efflux causes monocytosis. It is unknown whether cholesterol efflux capacity and monocyte subsets are associated in CKD. In 438 patients with CKD, mediators of cholesterol efflux capacity (high-density lipoprotein cholesterol/apolipoprotein A-I) and monocyte subsets were analyzed as predictors of cardiovascular events. Monocyte subset-specific intracellular lipid content, CD36, CD68, and ABCA1 were measured in a subgroup. Experimentally, we analyzed subset-specific cholesterol efflux capacity and response to oxidized low-density lipoprotein cholesterol stimulation in CKD. Epidemiologically, both low Apo-I and low high-density lipoprotein cholesterol were associated with high CD14 ++ CD16 + monocyte counts in linear regression analyses (apolipoprotein A-I: β=−0.171 P .001 high-density lipoprotein cholesterol: β=−0.138 P =0.005), but not with counts of other monocyte subsets. In contrast to apolipoprotein A-I or high-density lipoprotein cholesterol, higher CD14 ++ CD16 + monocyte counts independently predicted cardiovascular events (hazard ratio per increase of 1 cell/μL: 1.011 [1.003–1.020] P =0.007). Experimentally, CD14 ++ CD16 + monocytes demonstrated preferential lipid accumulation, high CD36, CD68, and low ABCA1 expression and, consequently, displayed low cholesterol efflux capacity, avid oxidized low-density lipoprotein cholesterol uptake, and potent intracellular interleukin-6, interleukin-1β, and tumor necrosis factor-α production. Taken together, mediators of cholesterol efflux are associated with CD14 ++ CD16 + monocyte counts, which independently predict adverse outcome in CKD.
Publisher: BMJ
Date: 31-05-2014
Publisher: Wiley
Date: 30-03-2005
DOI: 10.1111/J.1440-1681.2005.04178.X
Abstract: 1. In recent years demonstration of a direct association between slightly elevated serum levels of soluble proteins including the acute phase response proteins, selectins and intercellular adhesion molecules and the risk of developing vascular disease have been widely reported. These studies may provide the clinician with an insight into disease diagnosis, prognosis and disease activity. 2. The simplest interpretation of this data is that soluble proteins are just sensitive markers of inflammation. However, they may in fact be modulating inflammation directly through interaction with circulating cells. 3. Recent work has shown that these soluble proteins do indeed remain active and can bind to functional ligands expressed by circulating leucocytes. The current review focuses on the soluble proteins C-reactive protein and soluble P-selectin and describes previous studies characterizing their interaction with immune cells to modulate the pathogenesis of vascular disease. 4. The current review focuses on the soluble proteins C-reactive protein and soluble P-selectin and describes previous studies characterizing their interaction with immune cells to modulate the pathogenesis of vascular disease.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2017
Publisher: eLife Sciences Publications, Ltd
Date: 22-06-2023
Publisher: Elsevier BV
Date: 07-2008
DOI: 10.1016/J.ATHEROSCLEROSIS.2007.10.038
Abstract: Adhesion molecules have been implicated in the development and progression of cardiovascular disease, which is highly prevalent in people with diabetes. Adhesion molecules can mediate adhesion of leukocytes to the endothelium. Furthermore, P-selectin expressed on platelets is able to mediate the adhesion of leukocytes to platelets. In this study, we examine the in-vivo and in-vitro effects of rosiglitazone with particular emphasis on three important adhesion molecules (VCAM-1, ICAM-1 and P-selectin). In the aorta of STZ-diabetic apolipoprotein E-deficient (apoE KO) mice, rosiglitazone significantly reduced both total and arch plaque area. The mechanism for this appeared to be reduced macrophage infiltration into the atherosclerotic plaque which was also associated with reduced mRNA levels for VCAM-1, ICAM-1, MCP-1 and P-selectin in the aorta. In-vitro studies revealed reduced cell adhesion of monocytic cells (THP-1) to fibrinogen and endothelial cells (HUVEC) after incubation with rosiglitazone. Furthermore, the reduction in leukocyte adhesion also correlated with significant reductions in mRNA levels for VCAM-1, ICAM-1 and P-selectin indicating that reduced macrophage infiltration in atherosclerotic plaques may occur as a result of a direct effect of rosiglitazone on adhesion molecules in both monocytes and endothelial cells. Thus, we have shown that rosiglitazone appears to have direct anti-atherosclerotic effects in an animal model of diabetes-associated atherosclerosis which are at least partly due to effects on VCAM-1, ICAM-1, MCP-1 and P-selectin expression which leads to decreased leukocyte adhesion and macrophage infiltration.
Publisher: BMJ
Date: 05-2013
Publisher: Cold Spring Harbor Laboratory
Date: 29-06-0029
DOI: 10.1101/2020.06.19.161059
Abstract: Neutrophils or heterophils constitute the largest population of phagocytic granulocytes in the blood of mammals and birds. The development and function of neutrophils and monocytes is primarily governed by the granulocyte colony-stimulating factor receptor family (CSF3R/CSF3) and macrophage colony-stimulating factor receptor family (CSF1R/IL34/CSF1) respectively. Using various techniques this study considered how the emergence of receptor:ligand pairings shaped the distribution of blood myeloid cell populations. Comparative gene analysis supported the ancestral pairings of CSF1R/IL34 and CSF3R/CSF3, and the emergence of CSF1 later in tetrapod lineages after the advent of Jawed/Jawless fish. Further analysis suggested that the emergence of CSF3 lead to reorganisation of granulocyte distribution between hibian and early reptiles. However, the advent of endothermy likely contributed to the dominance of the neutrophil/heterophil in modern-day mammals and birds. In summary, we show that the emergence of CSF3R/CSF3 was a key factor in the subsequent evolution of the modern-day mammalian neutrophil. Colony-stimulating factors (CSFs) are important for myeloid phagocyte development. The emergence of CSF3/CSF3R in tetrapod lineages has uniquely contributed to physical, functional and structural adaptions observed in mammalian neutrophils.
Publisher: MyJove Corporation
Date: 23-08-2011
DOI: 10.3791/3221
Publisher: Springer International Publishing
Date: 2017
DOI: 10.1007/978-3-319-57613-8_7
Abstract: In this chapter, we discuss the manner through which the immune system regulates the cardiovascular system in health and disease. We define the cardiovascular system and elements of atherosclerotic disease, the main focus in this chapter. Herein we elaborate on the disease process that can result in myocardial infarction (heart attack), ischaemic stroke and peripheral arterial disease. We have discussed broadly the homeostatic mechanisms in place that help autoregulate the cardiovascular system including the vital role of cholesterol and lipid clearance as well as the role lipid homeostasis plays in cardiovascular disease in the context of atherosclerosis. We then elaborate on the role played by the immune system in this setting, namely, major players from the innate and adaptive immune system, as well as discussing in greater detail specifically the role played by monocytes and macrophages.This chapter should represent an overview of the role played by the immune system in cardiovascular homeostasis however further reading of the references cited can expand the reader's knowledge of the detail, and we point readers to many excellent reviews which summarise in idual immune systems and their role in cardiovascular disease.
Publisher: eLife Sciences Publications, Ltd
Date: 11-08-2023
DOI: 10.7554/ELIFE.85647
Abstract: Monocytes are heterogeneous innate effector leukocytes generated in the bone marrow and released into circulation in a CCR2-dependent manner. During infection or inflammation, myelopoiesis is modulated to rapidly meet the demand for more effector cells. Danger signals from peripheral tissues can influence this process. Herein we demonstrate that repetitive TLR7 stimulation via the epithelial barriers drove a potent emergency bone marrow monocyte response in mice. This process was unique to TLR7 activation and occurred independently of the canonical CCR2 and CX3CR1 axes or prototypical cytokines. The monocytes egressing the bone marrow had an immature Ly6C-high profile and differentiated into vascular Ly6C-low monocytes and tissue macrophages in multiple organs. They displayed a blunted cytokine response to further TLR7 stimulation and reduced lung viral load after RSV and influenza virus infection. These data provide insights into the emergency myelopoiesis likely to occur in response to the encounter of single-stranded RNA viruses at barrier sites.
Publisher: American Society of Hematology
Date: 04-12-2014
DOI: 10.1182/BLOOD-2014-07-588046
Abstract: This study has identified a novel mechanism by which TF expression is posttranscriptionally regulated in macrophages. The mechanism involves the control of mRNA stability by a cooperation between PARP-14 and TTP.
Publisher: Public Library of Science (PLoS)
Date: 26-03-2020
Publisher: Public Library of Science (PLoS)
Date: 20-05-2014
Publisher: Springer Science and Business Media LLC
Date: 12-01-2010
Publisher: The Company of Biologists
Date: 2016
DOI: 10.1242/DMM.024208
Abstract: The Wistar Kyoto rat (WKY) and the Spontaneously Hypertensive Rat (SHR) inbred strains are well-established models for human crescentic glomerulonephritis (CRGN) and metabolic syndrome respectively. Novel transgenic (Tg) strains add research opportunities and increase scientific value to well-established rat models. We have created two novel Tg strains using Sleeping Beauty transposon germline transgenesis, ubiquitously expressing green fluorescent protein (GFP) under the rat elongation factor 1 alpha (rEF1a) promoter on the WKY and SHR genetic backgrounds. The Sleeping Beauty system functioned with high transgenesis efficiency in our hands: 75% of the new rats born after embryo microinjections were transgene positive. By ligation-mediated PCR, we located the genome integration sites, confirming no exonic disruption and defining single or low copy number of the transgenes in the new WKY-GFP and SHR-GFP Tg lines. We report GFP bright expression in embryos, tissues and organs in both lines and show preliminary in vitro and in vivo imaging data that show the utility of the new GFP-expressing lines for adoptive transfer, transplantation and fate mapping studies of CRGN, metabolic syndrome and other traits for which these strains have been extensively studied over the past four decades.
Publisher: Wiley
Date: 02-2003
Publisher: Elsevier BV
Date: 05-2014
DOI: 10.1038/KI.2013.448
Abstract: The kidney has a erse repertoire of cells that make up the mononuclear phagocyte system (MPS). Wu et al. identify a population of CD8αα+CD11c+MHC-II+ blood precursors that display dendritic cell-like characteristics in the glomeruli. These cells show increased recruitment in a rat anti-glomerular basement membrane glomerulonephritis model and were able to attenuate disease. This study highlights the importance of the MPS in kidney disease and the need to better understand it to develop immunotherapeutics translatable to the renal patient.
Publisher: EMBO
Date: 05-12-2022
Publisher: Oxford University Press (OUP)
Date: 17-10-2002
DOI: 10.1046/J.1365-2249.2002.01978.X
Abstract: C-reactive protein (CRP) is the prototypic acute phase serum protein in humans. The effects of CRP on primary human monocyte adhesion molecule expression and interaction with the endothelium have not been studied. Herein, we describe an investigation into the phenotypic and functional consequences of CRP binding to peripheral blood monocytes ex vivo. Peripheral whole blood was collected from healthy, non-smoking males. Mononuclear cells (MNC) and monocytes were isolated by differential centrifugation using lymphoprep and Dynal negative isolation kit, respectively. Cells were exposed to CRP from 0 to 250 µg/ml for 0–60 min at 37°C and analysed for (a) CD11b, PECAM-1 (CD31) and CD32 expression by flow cytometry and (b) adhesion to LPS (1 µg/ml 0–24 h) treated human umbilical vein endothelial cells (HUVEC). CD14+ monocyte expression of CD11b increased significantly up to twofold when exposed to CRP, compared to controls. There was no significant difference in CD32 expression, whereas CD31 expression decreased after exposure to CRP. CRP treatment of monocytes inhibited their adhesion to early LPS-activated HUVEC (0–5 h). However, the adhesion of CRP-treated monocytes to HUVEC was significantly greater to late activation antigens on HUVEC (24 h, LPS) compared to controls. We have shown that CRP can affect monocyte activation ex vivo and induce phenotypic changes that result in an altered recruitment to endothelial cells. This study provides the first evidence for a further role for C-reactive protein in both monocyte activation and adhesion, which may be of importance during an inflammatory event.
Publisher: Elsevier BV
Date: 09-2015
Publisher: Springer Science and Business Media LLC
Date: 16-03-2017
Abstract: Monocytes are heterogeneous effector cells involved in the maintenance and restoration of tissue integrity. Monocytes and macrophages are involved in cardiovascular disease progression, and are associated with the development of unstable atherosclerotic plaques. Hyperlipidaemia can accelerate cardiovascular disease progression. However, monocyte responses to hyperlipidaemia are poorly understood. In the past decade, accumulating data describe the relationship between the dynamic blood lipid environment and the heterogeneous circulating monocyte pool, which might have profound consequences for cardiovascular disease. In this Review, we explore the updated view of monocytes in cardiovascular disease and their relationship with macrophages in promoting the homeostatic and inflammatory responses related to atherosclerosis. We describe the different definitions of dyslipidaemia, highlight current theories on the ontogeny of monocyte heterogeneity, discuss how dyslipidaemia might alter monocyte production, and explore the mechanistic interface linking dyslipidaemia with monocyte effector functions, such as migration and the inflammatory response. Finally, we discuss the role of dietary and endogenous lipid species in mediating dyslipidaemic responses, and the role of these lipids in promoting the risk of cardiovascular disease through modulation of monocyte behaviour.
Publisher: Bentham Science Publishers Ltd.
Date: 03-2007
DOI: 10.2174/187152807780077345
Abstract: P-selectin is an inflammatory adhesion molecule expressed on activated platelets and endothelial cells. The role of inflammatory cells and adhesion molecules in the development and progression of vascular diseases has been well studied in the past two decades and it is now recognised that many of the cellular and molecular events that underlie atherosclerotic vascular disease are inflammatory in nature. The critical role of P-selectin in both leukocyte recruitment and vascular disease progression has been confirmed in knockout animal models, where P-selectin knockout mice crossed with apoE deficient mice exhibit significantly reduced atherosclerosis and leukocyte recruitment in the plaque. Being the primary adhesion molecule in initiating cell activation and cell adhesion to platelets and endothelial cells, P-selectin is therefore an attractive therapeutic target in vascular disease. However the basic tenet of targeting P-selectin may be complicated by the presence of a soluble form of P-selectin (sP-selectin). sP-selectin, lacking the cytosolic/transmembrane domain, has been identified circulating in plasma and is thought to either be derived from the secretion of an alternatively spliced protein that lacks the transmembrane domain and/or from proteolytic cleavage of the membrane form, thus reflecting the activated state of both platelets and/or endothelial cells. This review will discuss the role of P-selectin in inflammatory disease particularly in atherosclerosis and will highlight current in vitro and in vivo discoveries.
Publisher: eLife Sciences Publications, Ltd
Date: 25-11-2020
DOI: 10.7554/ELIFE.60214
Abstract: Neutrophils constitute the largest population of phagocytic granulocytes in the blood of mammals. The development and function of neutrophils and monocytes is primarily governed by the granulocyte colony-stimulating factor receptor family (CSF3R/CSF3) and macrophage colony-stimulating factor receptor family (CSF1R/IL34/CSF1) respectively. Using various techniques this study considered how the emergence of receptor:ligand pairings shaped the distribution of blood myeloid cell populations. Comparative gene analysis supported the ancestral pairings of CSF1R/IL34 and CSF3R/CSF3, and the emergence of CSF1 later in lineages after the advent of Jawed/Jawless fish. Further analysis suggested that the emergence of CSF3 lead to reorganisation of granulocyte distribution between hibian and early reptiles. However, the advent of endothermy likely contributed to the dominance of the neutrophil/heterophil in modern-day mammals and birds. In summary, we show that the emergence of CSF3R/CSF3 was a key factor in the subsequent evolution of the modern-day mammalian neutrophil.
Publisher: Informa UK Limited
Date: 10-2006
Publisher: eLife Sciences Publications, Ltd
Date: 22-03-2020
Publisher: Springer Science and Business Media LLC
Date: 2011
Publisher: Elsevier BV
Date: 06-2002
Publisher: Rockefeller University Press
Date: 07-12-2009
DOI: 10.1084/JEM.20091586
Abstract: Most tissues develop from stem cells and precursors that undergo differentiation as their proliferative potential decreases. Mature differentiated cells rarely proliferate and are replaced at the end of their life by new cells derived from precursors. Langerhans cells (LCs) of the epidermis, although of myeloid origin, were shown to renew in tissues independently from the bone marrow, suggesting the existence of a dermal or epidermal progenitor. We investigated the mechanisms involved in LC development and homeostasis. We observed that a single wave of LC precursors was recruited in the epidermis of mice around embryonic day 18 and acquired a dendritic morphology, major histocompatibility complex II, CD11c, and langerin expression immediately after birth. Langerin+ cells then undergo a massive burst of proliferation between postnatal day 2 (P2) and P7, expanding their numbers by 10–20-fold. After the first week of life, we observed low-level proliferation of langerin+ cells within the epidermis. However, in a mouse model of atopic dermatitis (AD), a keratinocyte signal triggered increased epidermal LC proliferation. Similar findings were observed in epidermis from human patients with AD. Therefore, proliferation of differentiated resident cells represents an alternative pathway for development in the newborn, homeostasis, and expansion in adults of selected myeloid cell populations such as LCs. This mechanism may be relevant in locations where leukocyte trafficking is limited.
Publisher: Oxford University Press (OUP)
Date: 05-06-2015
DOI: 10.1111/CEI.12625
Abstract: Monocyte subsets with differing functional properties have been defined by their expression of CD14 and CD16. We investigated these subsets in anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) and determined their surface expression of ANCA autoantigens. Flow cytometry was performed on blood from 14 patients with active AAV, 46 patients with AAV in remission and 21 controls. The proportion of classical (CD14highCD16neg/low), intermediate (CD14highCD16high) and non-classical (CD14lowCD16high) monocytes and surface expression levels of CD14 and CD16 were determined, as well as surface expression of proteinase 3 (PR3) and myeloperoxidase (MPO) on monocyte subsets. There was no change in the proportion of monocytes in each subset in patients with AAV compared with healthy controls. The expression of CD14 on monocytes from patients with active AAV was increased, compared with patients in remission and healthy controls (P & 0·01). Patients with PR3-ANCA disease in remission also had increased monocyte expression of CD14 compared with controls (P & 0·01) however, levels in patients with MPO-ANCA disease in remission were lower than active MPO-ANCA patients, and not significantly different from controls. There was a correlation between CD14 and both PR3 and MPO expression on classical monocytes in AAV patients (r = 0·79, P & 0·0001 and r = 0·42, P & 0·005, respectively). In conclusion, there was an increase in monocyte CD14 expression in active AAV and PR3-ANCA disease in remission. The correlation of CD14 expression with ANCA autoantigen expression in AAV may reflect cell activation, and warrants further investigation into the potential for increased CD14 expression to trigger disease induction or relapse.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 17-07-2009
DOI: 10.1161/CIRCRESAHA.108.190611
Abstract: C-reactive protein (CRP) is a predictor of cardiovascular risk. It circulates as a pentamer (pentameric CRP) in plasma. The in vivo existence of monomeric (m)CRP has been postulated, but its function and source are not clear. We show that mCRP is deposited in human aortic and carotid atherosclerotic plaques but not in healthy vessels. pCRP is found neither in healthy nor in diseased vessels. As source of mCRP, we identify a mechanism of dissociation of pCRP to mCRP. We report that activated platelets, which play a central role in cardiovascular events, mediate this dissociation via lysophosphatidylcholine, which is present on activated but not resting platelets. Furthermore, the dissociation of pCRP to mCRP can also be mediated by apoptotic monocytic THP-1 and Jurkat T cells. The functional consequence is the unmasking of proinflammatory effects of CRP as demonstrated in experimental settings that are pathophysiologically relevant for atherogenesis: compared to pCRP, mCRP induces enhanced monocyte chemotaxis monocyte activation, as determined by conformational change of integrin Mac-1 generation of reactive oxygen species and monocyte adhesion under static and physiological flow conditions. In conclusion, we demonstrate mCRP generation via pCRP dissociation on activated platelets and H 2 O 2 -treated apoptotic THP-1 and Jurkat T cells, thereby identifying a mechanism of localized unmasking of the proinflammatory properties of CRP. This novel mechanism provides a potential link between the established cardiovascular risk marker, circulating pCRP, and localized platelet-mediated inflammatory and proatherogenic effects.
Publisher: Springer Science and Business Media LLC
Date: 17-09-2020
DOI: 10.1038/S41467-020-18454-0
Abstract: Unassisted metastasis through the lymphatic system is a mechanism of dissemination thus far ascribed only to cancer cells. Here, we report that Streptococcus pyogenes also hijack lymphatic vessels to escape a local infection site, transiting through sequential lymph nodes and efferent lymphatic vessels to enter the bloodstream. Contrasting with previously reported mechanisms of intracellular pathogen carriage by phagocytes, we show S. pyogenes remain extracellular during transit, first in afferent and then efferent lymphatics that carry the bacteria through successive draining lymph nodes. We identify streptococcal virulence mechanisms important for bacterial lymphatic dissemination and show that metastatic streptococci within infected lymph nodes resist and subvert clearance by phagocytes, enabling replication that can seed intense bloodstream infection. The findings establish the lymphatic system as both a survival niche and conduit to the bloodstream for S. pyogenes , explaining the phenomenon of occult bacteraemia. This work provides new perspectives in streptococcal pathogenesis with implications for immunity.
Publisher: Bentham Science Publishers Ltd.
Date: 12-2010
DOI: 10.2174/138161210794519192
Abstract: Inflammation plays a fundamental role in many chronic diseases, including atherosclerosis associated cardiovascular disease. Adhesion of immune cells plays a critical role in the inflammatory response and indeed the pathophysiology of inflammatory related diseases. P-selectin is an inflammatory adhesion molecule, enabling the recruitment of leukocytes to the endothelium and to activated platelets involved with the growing thrombus. P-selectin is critical in the progression of atherosclerosis as evidenced by knockout animal models where P-selectin knockout mice crossed with apoE deficient mice exhibit significantly reduced atherosclerosis and leukocyte recruitment in the plaque. A soluble form of P-selectin also exists, which may have pro-atherogenic and pro-thrombotic effects. Thus targeting of P-selectin remains a strong clinical candidate for developing novel therapeutic strategies in inflammatory diseases. This review will discuss the role of P-selectin and describe the function of P-selectin antagonists as clinical targets.
Publisher: Informa UK Limited
Date: 29-04-2014
DOI: 10.1517/13543776.2014.914495
Abstract: Monocytes and macrophages are heterogeneous populations of effector cells in the innate immune system. Once thought to be obligatory precursors for macrophages, monocytes are now known to have several distinct sub-populations and their own independent functions. This separation of the two lineages has opened new therapeutic avenues in inflammation and created new technologies targeting the mononuclear phagocyte system (MPS). A search of Google Patents and PatentScope has revealed numerous patents targeting monocytes and macrophages. This review will focus on seven patents from 2009 to 2013, utilizing autologous monocyte and macrophage adoptive transfer, genetic manipulation of the MPS, therapeutic nanoparticles and liposomes or combinations of these strategies. Patents that target monocyte recruitment are also briefly reviewed. While monocyte and macrophage targeting has yielded some promising results in animal models, these often fail to translate well to successful clinical trials. The paradigm of how cells in the MPS interact and evolve is constantly being updated, and caution must be exercised in developing immunomodulatory agents until this relationship is better understood.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-11-2008
DOI: 10.1161/CIRCRESAHA.108.182063
Abstract: Studies have shown a reduction in plaque volume and change in plaque ultrasound characteristics after 4 infusions of reconstituted high-density lipoprotein (rHDL). Whether rHDL infusion leads to acute changes in plaque characteristics in humans is not known. Patients with claudication scheduled for percutaneous superficial femoral artery revascularization were randomized to receive 1 intravenous infusion of either placebo or rHDL (80 mg/kg given over 4 hours). Five to 7 days following the infusion, patients returned and revascularization was performed including atherectomy to excise plaque from the superficial femoral artery. Twenty patients (17 males) average age, 68±10 years (mean±SD) were recruited. Eleven patients had a history of documented coronary artery disease, all patients were on aspirin, and 18 were on statins. Ten of the patients received rHDL and 10 placebo. There was significantly less vascular cell adhesion molecule-1 expression (28±3% versus 50±3% P .05) and a reduction in lipid content in the plaque of HDL-treated subjects compared to placebo. The level of HDL cholesterol increased by 20% after infusion of rHDL and the capacity of apolipoprotein B–depleted plasma to support cholesterol efflux increased. Intravenous infusion of a single dose of reconstituted HDL led to acute changes in plaque characteristics with a reduction in lipid content, macrophage size, and measures of inflammation. These changes may contribute to the cardioprotective effects of HDL.
Publisher: Cold Spring Harbor Laboratory
Date: 16-12-2020
DOI: 10.1101/2020.12.16.423021
Abstract: Synergy between GPIbα and GPVI signaling machineries has been suggested previously, however its molecular mechanism remains unclear. We generated a novel GPIbα transgenic mouse ( GPIbα Δsig/Δsig ) by CRISPR-Cas9 technology to delete the last 24 residues of the GPIbα intracellular tail important for VWF-mediated signaling. GPIbα Δsig/Δsig platelets bound VWF normally under flow but formed fewer filopodia on VWF/botrocetin, demonstrating that the deleted region does not affect ligand binding but appreciably impairs VWF-dependent signaling. Notably, while haemostasis was normal in GPIbα Δsig/Δsig mice, GPIbα Δsig/Δsig platelets exhibited defective responses after collagen-related-peptide stimulation and formed smaller aggregates on collagen-coated microchannels at low and high shears. Flow assays performed with plasma-free blood or in the presence of α IIb β 3 -or GPVI-blockers suggested reduced α IIb β 3 activation contributes to the phenotype of the GPIbα Δsig/Δsig platelets. Together, these results reveal a new role for the intracellular tail of GPIbα in transducing both VWF-GPIbα and collagen-GPVI signaling events in platelets. GPIbα and GPVI are two key receptors on the platelet surface. Using a novel transgenic mouse ( GPIbα Δsig/Δsig ) that lacks the last 24 amino acids of the GPIbα intracellular tail, we demonstrate the importance of this region not only in transducing signals in response to GPIbα binding to VWF, but also for collagen-GPVI-mediated platelet responses revealing previously underappreciated receptor crosstalk between GPIbα and GPVI.
Publisher: American Society of Hematology
Date: 15-09-2007
DOI: 10.1182/BLOOD-2006-08-040980
Abstract: The ability of platelets to provide a highly reactive surface for the recruitment of other platelets and leukocytes to sites of vascular injury is critical for hemostasis, atherothrombosis, and a variety of inflammatory diseases. The mechanisms coordinating platelet-platelet and platelet-leukocyte interactions have been well defined and, in general, it is assumed that increased platelet activation correlates with enhanced reactivity toward other platelets and neutrophils. In the current study, we demonstrate a differential role for platelets in supporting platelet and neutrophil adhesive interactions under flow. We demonstrate that the conversion of spread platelets to microvesiculated procoagulant (annexin A5–positive [annexin A5+ve]) forms reduces platelet-platelet adhesion and leads to a paradoxical increase in neutrophil-platelet interaction. This enhancement in neutrophil adhesion and spreading is partially mediated by the proinflammatory lipid, platelet-activating factor (PAF). PAF production, unlike other neutrophil chemokines (IL-8, GRO-α, NAP-2, IL-1β) is specifically and markedly up-regulated in annexin A5+ve cells. Physiologically, this spatially controlled production of PAF plays an important role in localizing neutrophils on the surface of thrombi. These studies define for the first time a specific proinflammatory function for annexin A5+ve platelets. Moreover, they demonstrate an important role for platelet-derived PAF in spatially regulating neutrophil adhesion under flow.
Publisher: Oxford University Press (OUP)
Date: 09-03-2018
DOI: 10.1111/CEI.13111
Abstract: Hyperlipidaemia accompanies chronic renal disease either as a consequence of the renal dysfunction or as part of generalized metabolic derangements. Under both situations, the lipid profile is characterized by accumulation of triglyceride-rich lipoproteins (TGRLs). This lipid profile is recognized as a risk factor for cardiovascular complications. Whether it may pose a risk for renal injury as well remains unclear. A hyper-TGRL state was generated in C57BL/6 mice using poloxamer-407 (P-407) and immune complex-mediated renal injury was triggered using the accelerated nephrotoxic nephritis (ANTN) model. The hyper-TGRL animals were hypersensitive to ANTN demonstrated by greater haematuria and glomerular cellularity. These changes were accompanied by increased glomerular accumulation of CD68+ macrophages. The hypersensitive response to ANTN was not seen in low-density lipoprotein receptor knock-out mice fed with a high fat diet, where triglyceride levels were lower but cholesterol levels comparable to those obtained using P-407. These data indicate that a hyper-TGRL state might be more detrimental to the kidneys than low-density lipoprotein-driven hypercholesterolaemia during immune complex-mediated nephritis. We speculate that the hyper-TGRL environment primes the kidney to exacerbated renal damage following an inflammatory insult with increased accumulation of macrophages that may play a key role in mediating the injurious effects.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2011
DOI: 10.1161/ATVBAHA.111.226258
Abstract: Neutrophils play a key role in the immune response but can undesirably exacerbate inflammation. High-density lipoproteins (HDL) are antiinflammatory particles, exerting beneficial cardiovascular influences. We determined whether HDL exerts antiinflammatory effects on neutrophils and explored the mechanisms by which these occur. CD11b on activated human neutrophils was significantly attenuated by apolipoprotein A-I (apoA-I) and HDL. The effects of apoA-I were mediated via ABCA1, whereas the effects of HDL were via scavenger receptor BI. Both were associated with a reduction in the abundance of lipid rafts, and a strong correlation between raft abundance and CD11b activation was observed. ApoA-I and HDL reduced neutrophil adhesion to a platelet monolayer under shear flow, as well as neutrophil spreading and migration. ApoA-I also inhibited leukocyte recruitment to the endothelium in an acute in vivo model of inflammation. Finally, infusion of reconstituted HDL in patients with peripheral vascular disease was demonstrated to significantly attenuate neutrophil activation. We describe here a novel role for HDL and apoA-I in regulating neutrophil activation using in vitro, in vivo, and clinical approaches. We also show that these effects of HDL and apoA-I involve a mechanism requiring changes in membrane domain content rather than in cholesterol efflux per se.
Publisher: Proceedings of the National Academy of Sciences
Date: 29-10-2021
Abstract: With rare exceptions, an antiferromagnetic (AFM) transition in zero magnetic field is thermodynamically of second order where the thermal-average magnetic moments of the magnetic atoms (ordered moments) vary continuously on cooling through the AFM ordering temperature T N with no latent heat at the transition. Such materials include the AFM pnictides CaMn 2 As 2 , SrMn 2 As 2 , CaMn 2 Sb 2 , SrMn 2 Sb 2 , and CaMn 2 Bi 2 . Here we demonstrate that the closely related SrMn 2 P 2 and CaMn 2 P 2 insulators instead exhibit first-order AFM transitions at T N = 53 and 70 K, respectively, where the heat capacity exhibits a latent heat at T N . The mechanism causing these first-order transitions remains to be explained, but its understanding may lead to the development of novel magnetic materials of technological interest.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 31-08-2020
Abstract: Monocytes and macrophages are important in mediating crescentic GN (CrGN), but little work has been done to phenotype the subpopulations involved and determine their respective contributions to glomerular inflammation. Using nephrotoxic nephritis in the rat as a clinically relevant experimental model of CrGN, we show that this is a predominantly intravascular disease and that glomerular inflammation and damage is driven by dynamic interactions between intravascular blood monocytes and the endothelium. Monocyte subsets had distinct phenotypes and effector functions: non-classical monocytes were recruited to the glomerulus first, and may orchestrate the inflammatory response. Later recruitment of classical monocytes was associated with glomerular damage and proteinuria. Targeting specific monocyte subpopulations may generate less toxic and more effective therapies for patients with GN. Immune complexes within glomerular capillary walls cause crescentic GN (CrGN). Monocytes and macrophages are important in mediating CrGN, but little work has been done to phenotype the subpopulations involved and determine their respective contributions to glomerular inflammation. Live glomerular imaging using confocal microscopy monitored intravascular monocyte subset behavior during nephrotoxic nephritis (NTN) in a novel WKY-hCD68-GFP monocyte/macrophage reporter rat strain. Flow cytometry and qPCR further analyzed ex vivo the glomerular leukocyte infiltrate during NTN. Non-classical monocytes surveyed the glomerular endothelium via lymphocyte function-associated antigen 1 (LFA-1) in the steady state. During NTN, non-classical monocytes were recruited first, but subsequent recruitment and retention of classical monocytes was associated with glomerular damage. Monocytes recruited to the glomerular vasculature did not undergo transendothelial migration. This finding suggests that inflammation in immune complex-mediated CrGN is predominantly intravascular, driven by dynamic interactions between intravascular blood monocytes and the endothelium. Glomerular endothelium and non-classical monocytes overexpressed a distinct chemokine axis, which may orchestrate inflammatory myeloid cell recruitment and expression of damage mediators. Reduced classical monocyte recruitment in Lewis rats during NTN confirmed a role for CD16 in mediating glomerular damage. Monocyte subsets with distinct phenotypes and effector functions may be important in driving inflammation in experimental CrGN resulting from immune complexes formed within the glomerular capillary wall. LFA-1–dependent endothelial surveillance by non-classical monocytes may detect immune complexes through CD16, orchestrating the inflammatory response through intravascular retention of classical monocytes, which results in glomerular damage and proteinuria.
Publisher: Cold Spring Harbor Laboratory
Date: 07-02-2023
DOI: 10.1101/2023.02.06.527328
Abstract: Monocytes are heterogeneous innate effector leukocytes generated in the bone marrow and released into circulation in a CCR2-dependent manner. During infection or inflammation myelopoiesis is modulated to rapidly meet demand for more effector cells. Danger signals from peripheral tissues can influence this process. Herein we demonstrate that repetitive TLR7 stimulation via the epithelial barriers drove a potent emergency bone marrow monocyte response. This process was unique to TLR7 activation and occurred independently of the canonical CCR2 and CX3CR1 axes or prototypical cytokines. The monocytes egressing the bone marrow had an immature Ly6C-high profile and differentiated into vascular Ly6C-low monocytes and tissue macrophages in multiple organs. They displayed a blunted cytokine response to further TLR7 stimulation and reduced lung viral load after RSV and influenza virus infection. These data provide insights into the emergency myelopoiesis likely to occur in response to the encounter of single-stranded RNA viruses at barrier sites.
Publisher: American Society for Clinical Investigation
Date: 15-02-2021
DOI: 10.1172/JCI140196
Publisher: Mary Ann Liebert Inc
Date: 2006
Abstract: Poly(epsilon-caprolactone) (PCL) fibers produced by wet spinning from solutions in acetone under lowshear (gravity-flow) conditions resulted in fiber strength of 8 MPa and stiffness of 0.08 Gpa. Cold drawing to an extension of 500% resulted in an increase in fiber strength to 43 MPa and stiffness to 0.3 GPa. The growth rate of human umbilical vein endothelial cells (HUVECs) (seeded at a density of 5 x 10(4) cells/mL) on as-spun fibers was consistently lower than that measured on tissue culture plastic (TCP) beyond day 2. Cell proliferation was similar on gelatin-coated fibers and TCP over 7 days and higher by a factor of 1.9 on 500% cold-drawn PCL fibers relative to TCP up to 4 days. Cell growth on PCL fibers exceeded that on Dacron monofilament by at least a factor of 3.7 at 9 days. Scanning electron microscopy revealed formation of a cell layer on s les of cold-drawn and gelatin-coated fibers after 24 hours in culture. Similar levels of ICAM-1 expression by HUVECs attached to PCL fibers and TCP were measured using RT-PCR and flow cytometry, indicative of low levels of immune activation. Retention of a specific function of HUVECs attached to PCL fibers was demonstrated by measuring their immune response to lipopolysaccharide. Levels of ICAM-1 expression increased by approximately 11% in cells attached to PCL fibers and TCP. The high fiber compliance, favorable endothelial cell proliferation rates, and retention of an important immune response of attached HUVECS support the use of gravity spun PCL fibers for three-dimensional scaffold production in vascular tissue engineering.
Publisher: eLife Sciences Publications, Ltd
Date: 21-04-2020
DOI: 10.7554/ELIFE.53353
Abstract: Platelet-neutrophil interactions are important for innate immunity, but also contribute to the pathogenesis of deep vein thrombosis, myocardial infarction and stroke. Here we report that, under flow, von Willebrand factor/glycoprotein Ibα-dependent platelet ‘priming’ induces integrin α IIb β 3 activation that, in turn, mediates neutrophil and T-cell binding. Binding of platelet α IIb β 3 to SLC44A2 on neutrophils leads to mechanosensitive-dependent production of highly prothrombotic neutrophil extracellular traps. A polymorphism in SLC44A2 (rs2288904-A) present in 22% of the population causes an R154Q substitution in an extracellular loop of SLC44A2 that is protective against venous thrombosis results in severely impaired binding to both activated α IIb β 3 and VWF-primed platelets. This was confirmed using neutrophils homozygous for the SLC44A2 R154Q polymorphism. Taken together, these data reveal a previously unreported mode of platelet-neutrophil crosstalk, mechanosensitive NET production, and provide mechanistic insight into the protective effect of the SLC44A2 rs2288904-A polymorphism in venous thrombosis.
Publisher: Wiley
Date: 17-06-2010
DOI: 10.1111/J.1440-1681.2009.05338.X
Abstract: 1. Inflammation is an important process, driving the progression of atherosclerosis. Stemming inflammation may be a mechanism to inhibit the progression of this disease. 2. High-density lipoprotein (HDL), a particle inversely related to cardiovascular disease, has been described as having a number of anti-inflammatory functions. It has been shown that HDL inhibits endothelial inflammation in both in vitro and in vivo models, reducing the expression of key cell adhesion molecules. In addition, HDL has been shown to have an effect on the coagulation pathway by inhibiting platelet activation and reducing thrombus formation. Furthermore, by reducing the activation of leucocytes, HDL can inhibit leucocyte recruitment to the endothelium. 3. High-density lipoprotein infusion studies conducted in patients with inflammatory diseases have shown that acute treatment with HDL can effectively inhibit inflammation in vivo. Thus, HDL has been proven to be a potent inhibitor of inflammation, acting on a number of pathways, and this may suggest that HDL could be applied as an anti-inflammatory molecule for a number of diseases. 4. The present review highlights these important studies and reviews data on the anti-inflammatory effects of HDL from in vitro and in vivo studies, in both humans and animal models of atherosclerosis and inflammatory-related diseases.
Publisher: Springer Science and Business Media LLC
Date: 29-01-2016
DOI: 10.1038/SREP20038
Abstract: Blood monocytes are heterogeneous effector cells of the innate immune system. In circulation these cells are constantly in contact with lipid-rich lipoproteins, yet this interaction is poorly characterised. Our aim was to examine the functional effect of hyperlipidaemia on blood monocytes. In the Ldlr −/− mouse monocytes rapidly accumulate cytoplasmic neutral lipid vesicles during hyperlipidaemia. Functional analysis in vivo revealed impaired monocyte chemotaxis towards peritonitis following high fat diet due to retention of monocytes in the greater omentum. In vitro assays using human monocytes confirmed neutral lipid vesicle accumulation after exposure to LDL or VLDL. Neutral lipid accumulation did not inhibit phagocytosis, endothelial adhesion, intravascular crawling and transmigration. However, lipid loading led to a migratory defect towards C5a and disruption of cytoskeletal rearrangement, including an inhibition of RHOA signaling. These data demonstrate distinct effects of hyperlipidaemia on the chemotaxis and cytoskeletal regulation of monocyte subpopulations. These data emphasise the functional consequences of blood monocyte lipid accumulation and reveal important implications for treating inflammation, infection and atherosclerosis in the context of dyslipidaemia.
Publisher: BMJ
Date: 05-2013
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-11-2008
DOI: 10.1161/CIRCRESAHA.108.180273
Abstract: Plasma soluble P-selectin (sP-selectin) levels are increased in pathologies associated with atherosclerosis, including peripheral arterial occlusive disease (PAOD). However, the role of sP-selectin in regulating leukocyte–endothelial adhesion is unclear. The aim of this study was to assess the ability of exogenous and endogenous sP-selectin to induce leukocyte responses that promote their adhesion to various forms of endothelium. In flow chamber assays, sP-selectin dose-dependently increased neutrophil adhesion to resting human iliac artery endothelial cells. Similarly, sP-selectin induced neutrophil adhesion to the endothelial surface of murine aortae and human radial venous segments in ex vivo flow chamber experiments. Using intravital microscopy to examine postcapillary venules in the mouse cremaster muscle, in vivo administration of sP-selectin was also found to significantly increase leukocyte rolling and adhesion in unstimulated postcapillary venules. Using a Mac-1–specific antibody and P-selectin knockout mouse, it was demonstrated that this finding was dependent on a contribution of Mac-1 to leukocyte rolling and endothelial P-selectin expression. This was confirmed in an ex vivo perfusion model using viable mouse aorta and human radial vessels. In contrast, with tumor necrosis factor-α–activated endothelial cells and intact endothelium, where neutrophil adhesion was already elevated, sP-selectin failed to further increase adhesion. Plasma s les from PAOD patients containing pathologically elevated concentrations of sP-selectin also increased neutrophil adhesion to the endothelium in a sP-selectin–dependent manner, as demonstrated by immunodepletion of sP-selectin. These studies demonstrate that raised plasma sP-selectin may influence the early progression of vascular disease by promoting leukocyte adhesion to the endothelium in PAOD, through Mac-1–mediated rolling and dependent on endothelial P-selectin expression.
Publisher: Research Square Platform LLC
Date: 06-10-2021
DOI: 10.21203/RS.3.RS-944388/V1
Abstract: C-reactive protein (CRP) is an acute phase protein. We recently identified a novel mechanism that leads to a conformational change from the native, pentameric structure (pCRP) to a pentameric intermediate (pCRP*) and ultimately to the monomeric form, mCRP, both being highly pro-inflammatory. This ‘CRP activation’ is mediated by binding of pCRP to activated/damaged cell membranes via exposed phosphocholine (PC) lipid head groups. We designed a low molecular weight pCRP – PC inhibitor, C10M. Binding assays and X-ray crystallography revealed direct, competitive binding of C10M to pCRP, blocking interaction with PC and thereby inhibiting formation of pCRP*/mCRP and their pro-inflammatory effects. The anti-inflammatory potential of C10M was confirmed in-vitro by various measures of leukocyte and endothelial cell activation and in-vivo in rat models of acute ischemia/reperfusion injury and hindlimb transplantation. In conclusion, inhibition of pCRP*/mCRP generation via the PC-mimicking compound C10M represents a promising, potentially broadly applicable anti-inflammatory therapy.
Publisher: Cold Spring Harbor Laboratory
Date: 16-08-2023
DOI: 10.1101/2023.08.14.553197
Abstract: Checkpoint inhibitor-induced hepatitis (CPI-hepatitis) is an emerging problem with the widening use of CPIs in cancer immunotherapy. Here, we developed a mouse model to characterise the mechanism of CPI-hepatitis and to therapeutically target key pathways driving this pathology. C57BL/6 wild-type (WT) mice were dosed with TLR9-agonist (TLR9-L) for hepatic priming combined with anti-CTLA-4 plus anti-PD-1 (CPI) or control (PBS) for up to 7 days. Co-administration of CPIs with TLR9-L induced liver pathology closely resembling human disease, with increased infiltration and clustering of granzyme B + perforin + CD8 + T cells and CCR2 + monocytes, 7 days post treatment. This was accompanied by apoptotic hepatocytes surrounding these clusters and elevated cytokeratin-18 and alanine transaminase plasma levels. Liver RNA sequencing identified key signalling pathways (JAK-STAT, NF- κ B) and cytokine/chemokine networks ( Ifnγ, Cxcl9, Ccl2/Ccr2 ) as drivers of CPI-hepatitis. Using this model, we show that CD8 + T cells mediate hepatocyte damage in experimental CPI-hepatitis. However, their liver recruitment, clustering, and cytotoxic activity is dependent the presence of CCR2 + monocytes. Absence of hepatic monocyte recruitment in Ccr2 rfp/rfp mice and CCR2 therapeutic inhibition by cenicriciroc (CVC) in WT mice prevented CPI-hepatitis. In conclusion, using this newly established mouse model, we demonstrate a central role of liver infiltrating CCR2 + monocyte interaction with cytotoxic CD8 + T cells in the pathogenesis of CPI-hepatitis and highlight novel therapeutic targets.
Publisher: Springer Science and Business Media LLC
Date: 15-01-2014
DOI: 10.1038/NCOMMS4039
Abstract: Tuned and distinct responses of macrophages and dendritic cells to Toll-like receptor 4 (TLR4) activation induced by lipopolysaccharide (LPS) underpin the balance between innate and adaptive immunity. However, the molecule(s) that confer these cell-type-specific LPS-induced effects remain poorly understood. Here we report that the integrin α M (CD11b) positively regulates LPS-induced signalling pathways selectively in myeloid dendritic cells but not in macrophages. In dendritic cells, which express lower levels of CD14 and TLR4 than macrophages, CD11b promotes MyD88-dependent and MyD88-independent signalling pathways. In particular, in dendritic cells CD11b facilitates LPS-induced TLR4 endocytosis and is required for the subsequent signalling in the endosomes. Consistent with this, CD11b deficiency d ens dendritic cell-mediated TLR4-triggered responses in vivo leading to impaired T-cell activation. Thus, by modulating the trafficking and signalling functions of TLR4 in a cell-type-specific manner CD11b fine tunes the balance between adaptive and innate immune responses initiated by LPS.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2008
DOI: 10.1161/ATVBAHA.108.168690
Abstract: Objective— Whereas the anti–inflammatory effects of high-density lipoprotein (HDL) on endothelial cells are well described, such effects on monocytes are less studied. Methods and Results— Human monocytes were isolated from whole blood followed by assessment of CD11b activation/expression and cell adhesion under shear-flow. HDL caused a dose-dependent reduction in the activation of CD11b induced by PMA or receptor-dependent agonists. The constituent of HDL responsible for the antiinflammatory effects on CD11b activation was found to be apolipoprotein A-I (apoA-I). Cyclodextrin, but not cyclodextrin/cholesterol complex, also inhibited PMA-induced CD11b activation implicating cholesterol efflux as the main mechanism. This was further confirmed with the demonstration that cholesterol content of lipid rafts diminished after treatment with the cholesterol acceptors. Blocking ABCA1 with an anti-ABCA1 antibody abolished the effect of apoA-I. Furthermore, monocytes derived from a Tangier disease patient definitively confirmed the requirement of ABCA1 in apoA-I–mediated CD11b inhibition. The antiinflammatory effects of apoA-I were also observed in functional models including cell adhesion to an endothelial cell monolayer, monocytic spreading under shear flow, and transmigration. Conclusions— HDL and apoA-I exhibit an antiinflammatory effect on human monocytes by inhibiting activation of CD11b. ApoA-I acts through ABCA1, whereas HDL may act through several receptors.
Publisher: Bentham Science Publishers Ltd.
Date: 02-2009
DOI: 10.2174/092986709787458425
Abstract: It is well recognised that increased levels of high density lipoprotein (HDL) protect against atherosclerosis and correlate with improved prognosis for vascular disease associated events. While many of the atheroprotective effects of HDL are ascribed to the ability to remove cholesterol from the vasculature through the reverse cholesterol transport system, recent work has shown that HDL may be atheroprotective through its other functions, such as regulation of endothelial adhesion molecule expression, stimulation of endothelial nitric oxide synthase and inhibition of the damaging effects of oxidised low density lipoproteins. Recently, HDL has also been described to interact with circulating cells inhibiting both leukocyte and platelet activation, therefore having further systemic anti-inflammatory functions. This review summarises the studies and models used to examine the anti-inflammatory effects of HDL and details data describing the ability to inhibit leukocyte activation, contributing to the hypothesis that raised HDL is beneficial in the context of inflammation in atherosclerosis. Further, HDL modification in disease and current therapeutic strategies such as reconstituted HDL particles and apoA I mimetic peptides is discussed to provide insights to the potential applicability of raising HDL to regress cardiovascular disease.
Publisher: Portland Press Ltd.
Date: 07-05-2013
DOI: 10.1042/CS20120576
Abstract: Cardiovascular disease is the leading cause of death in several countries. The underlying process is atherosclerosis, a slowly progressing chronic disorder that can lead to intravascular thrombosis. There is overwhelming evidence for the underlying importance of our immune system in atherosclerosis. Monocytes, which comprise part of the innate immune system, can be recruited to inflamed endothelium and this recruitment has been shown to be proportional to the extent of atherosclerotic disease. Monocytes undergo migration into the vasculature, they differentiate into macrophage phenotypes, which are highly phagocytic and can scavenge modified lipids, leading to foam cell formation and development of the lipid-rich atheroma core. This increased influx leads to a highly inflammatory environment and along with other immune cells can increase the risk in the development of the unstable atherosclerotic plaque phenotype. The present review provides an overview and description of the immunological aspect of innate and adaptive immune cell subsets in atherosclerosis, by defining their interaction with the vascular environment, modified lipids and other cellular exchanges. There is a particular focus on monocytes and macrophages, but shorter descriptions of dendritic cells, lymphocyte populations, neutrophils, mast cells and platelets are also included.
Publisher: BMJ
Date: 27-04-2017
DOI: 10.1136/GUTJNL-2016-313615
Abstract: Acute liver failure (ALF) is characterised by overwhelming hepatocyte death and liver inflammation with massive infiltration of myeloid cells in necrotic areas. The mechanisms underlying resolution of acute hepatic inflammation are largely unknown. Here, we aimed to investigate the impact of Mer tyrosine kinase (MerTK) during ALF and also examine how the microenvironmental mediator, secretory leucocyte protease inhibitor (SLPI), governs this response. Flow cytometry, immunohistochemistry, confocal imaging and gene expression analyses determined the phenotype, functional/transcriptomic profile and tissue topography of MerTK+ monocytes/macrophages in ALF, healthy and disease controls. The temporal evolution of macrophage MerTK expression and its impact on resolution was examined in APAP-induced acute liver injury using wild-type (WT) and Mer-deficient (Mer −/− ) mice. SLPI effects on hepatic myeloid cells were determined in vitro and in vivo using APAP-treated WT mice. We demonstrate a significant expansion of resolution-like MerTK+HLA-DR high cells in circulatory and tissue compartments of patients with ALF. Compared with WT mice which show an increase of MerTK+MHCII high macrophages during the resolution phase in ALF, APAP-treated Mer −/− mice exhibit persistent liver injury and inflammation, characterised by a decreased proportion of resident Kupffer cells and increased number of neutrophils. Both in vitro and in APAP-treated mice, SLPI reprogrammes myeloid cells towards resolution responses through induction of a MerTK+HLA-DR high phenotype which promotes neutrophil apoptosis and their subsequent clearance. We identify a hepatoprotective, MerTK+, macrophage phenotype that evolves during the resolution phase following ALF and represents a novel immunotherapeutic target to promote resolution responses following acute liver injury.
Publisher: Elsevier BV
Date: 08-2003
DOI: 10.1016/S0006-291X(03)01383-4
Abstract: Regulation of monocyte adhesion molecule gene expression is via redox sensitive transcription factors. We have investigated whether dietary antioxidant supplementation with vitamin C (250 mg/day) can modulate monocyte ICAM-1 expression in healthy male subjects with low plasma vitamin C at baseline. In a randomised, double-blind, crossover study, monocyte ICAM-1 mRNA was analysed using quantitative reverse transcriptase PCR. Protein was determined by flow cytometry (monocytes) and ELISA (plasma). Monocyte numbers were unaltered by supplementation. Subjects with low plasma vitamin C (<50 microM) prior to supplementation expressed higher levels of monocyte ICAM-1mRNA, and showed a significant (50%) reduction in ICAM-1mRNA expression after 6 weeks of 250 mg/day vitamin C supplementation (p<0.05). This was paralleled by a reduction in sICAM-1 (p<0.05). For the first time, these results show that dietary vitamin C can modulate monocyte ICAM-1 gene expression in vivo, where regulation of gene expression represents a novel mechanism for benefit from dietary antioxidants.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-01-2006
DOI: 10.1161/01.RES.0000199295.14073.69
Abstract: Raised levels of soluble P-selectin (sP-selectin) have been reported in the plasma of patients with vascular diseases however, the functional importance of this ligand remains unclear. In this study we have examined a potential role for plasma sP-selectin in regulating neutrophil adhesion in patients with peripheral arterial occlusive disease (PAOD). Patients with PAOD had significantly higher levels of sP-selectin (mean±SD: 73.3±13.0 versus 16.7±6.4 ng/mL) and enhanced whole blood leukocyte adhesion to platelets under shear. To examine whether the raised sP-selectin levels can directly influence leukocyte adhesion, isolated neutrophils were incubated with plasma from PAOD patients before and after immunodepletion of sP-selectin. Neutrophil adhesion to fibrinogen increased 2-fold following incubation with PAOD plasma, which was abrogated on sP-selectin immunodepletion. We subsequently demonstrated that recombinant sP-selectin dose-dependently (75 to 250 ng/mL) increased leukocyte adhesion to fibrinogen and platelet monolayers. This increase was PSGL-1 and Src kinase-dependent and correlated with an increase in sP-selectin-mediated Mac-1 activation. sP-selectin–stimulated neutrophil adhesion to platelet monolayers was inversely correlated with shear, such that at low shear (50 s −1 ) a 92.7%±15.7 increase in adhesion was observed decreasing to 38.5%±11.9 at 150 s −1 and 10.1%±7.4 at 300 s −1 . These studies suggest a potentially important role for sP-selectin in modulating neutrophil adhesion in patients with PAOD, particularly at sites of low shear, where it raises the possibility that raised plasma sP-selectin levels may enhance leukocyte recruitment to vascular injury and promote disease progression.
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
Location: Switzerland
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2008
End Date: 2010
Funder: Australian Research Council
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