Patricia Green - Academia.edu (original) (raw)

Papers by Patricia Green

Circulation Research, 2021

Rationale: Inflammation is a basic component of the pathogenesis of atherosclerosis. CD200 is an ... more Rationale: Inflammation is a basic component of the pathogenesis of atherosclerosis. CD200 is an immune checkpoint known to control macrophage activation. CD200 recently emerged in the Framingham Heart Study and 2 other cohorts as being potentially relevant in cardiovascular disease. The role of this pathway in cardiovascular disease is unknown. Objective: We sought to examine the role of CD200 in atherosclerosis. Methods and Results: Using hypercholesterolemic apolipoprotein-E deficient mice, we demonstrate that whole-body CD200 deficiency augments atherosclerotic lesion formation and vulnerability. Administration of a CD200-Fusion protein reduces neointima formation. Our data show that the CD200-CD200R pathway restrains activation of CD200R+ lesional macrophages, their production of CCR2 ligands, and monocyte recruitment in vitro and in vivo in an air pouch model. Loss of CD200 leads to an excessive accumulation of classical Ly6C hi monocytes and CCR2 + macrophages within the athe...

Cardiovascular Research, 2018

Background: A deeper understanding of the immunogenicity of abdominal aortic aneurysms (AAA) is n... more Background: A deeper understanding of the immunogenicity of abdominal aortic aneurysms (AAA) is needed. Characterisation of AAA using flow cytometry is limited by significant autofluorescence and debris. Mass cytometry (CyTOF) overcomes this and allows for deep multiparameter phenotyping. Methods: AAA specimens were collected intraoperatively and processed in a step-wise manner, using enzymatic digestion in combination with mechanical disaggregation. Enrichment by sorting CD45 cells with flow cytometry was performed prior to single cell characterisation with a tailored CyTOF panel of 37 antibodies. Results: There is a persistent inflammatory cell infiltrate dominated by lymphocytes within the aortic wall. CD3þ T cells constitute 52% of CD45þ cells and B cells make up 40%. Within the T Cells, 70% are CD4 T cells and 30% are CD8þ. The CD4 cells have no dominant Th1/Th2 pattern. There is only a small (1%) population of CD25þFOXP3 T-regulatory cells and the CD8 T cells have a distinct population of previously undescribed cytotoxic GranzymeBþCD27-cells. The majority of the B Cells are CD19þIGMþ and include a population of CD1dþ B cells that have been associated with lipid presentation. These immune cell phenotypes were homogenous across all the study patients. Conclusion: T and B cells dominate the AAA cell infiltrate suggesting persistent inflammation even in advanced disease. Using CyTOF, a more complete picture of the immune landscape emerges, thus allowing us to untangle the complex immune environment.

Cardiovascular research, Jan 2, 2018

Atherosclerosis is characterised by the abundant infiltration of myeloid cells starting at early ... more Atherosclerosis is characterised by the abundant infiltration of myeloid cells starting at early stages of disease. Myeloid cells are key players in vascular immunity during atherogenesis. However, the subsets of vascular myeloid cells have eluded resolution due to shared marker expression and atypical heterogeneity in vascular tissues. We applied the high-dimensionality of mass cytometry to the study of myeloid cell subsets in atherosclerosis. Apolipoprotein E-deficient (ApoE-/-) mice were fed a chow or a high fat (western) diet for 12 weeks. Single cell aortic preparations were probed with a panel of 35 metal-conjugated antibodies using Cytometry by time of flight (CyTOF). Clustering of marker expression on live CD45+ cells from the aortas of ApoE-/- mice identified 13 broad populations of leucocytes. Monocyte, macrophage, type 1 and type 2 conventional dendritic cell (cDC1 and cDC2), plasmacytoid dendritic cell (pDC), neutrophil, eosinophil, B cell, CD4+ and CD8+ T cell, γδ T cel...

Circulation, Jan 11, 2017

Background -Myeloid cells are central to atherosclerotic lesion development and vulnerable plaque... more Background -Myeloid cells are central to atherosclerotic lesion development and vulnerable plaque formation. Impaired ability of arterial phagocytes to uptake apoptotic cells (efferocytosis), promotes lesion growth and establishment of a necrotic core. The transcription factor Interferon Regulatory Factor (IRF)-5 is an important modulator of myeloid function and programming. We sought to investigate whether IRF5 affects the formation and phenotype of atherosclerotic lesions. Methods -We investigated the role of IRF5 in atherosclerosis in two complementary models. First, atherosclerotic lesion development in hyperlipidemic apolipoprotein E-deficient (ApoE(-/-)) mice and ApoE(-/-) mice with a genetic deletion of IRF5 (ApoE(-/-)Irf5(-/-)) was compared then lesion development was assessed in a model of shear stress modulated vulnerable plaque formation. Results -Both lesion size and necrotic core size were significantly reduced in ApoE(-/-)Irf5(-/-) mice compared to IRF5 competent ApoE(...

Proceedings of the National Academy of Sciences of the United States of America, Jan 5, 2015

Atherosclerosis is the major cause of cardiovascular disease (CVD), the leading cause of death wo... more Atherosclerosis is the major cause of cardiovascular disease (CVD), the leading cause of death worldwide. Despite much focus on lipid abnormalities in atherosclerosis, it is clear that the immune system also has important pro- and antiatherogenic functions. The enzyme indoleamine-2,3-dioxygenase (IDO) catalyses degradation of the essential amino acid tryptophan into immunomodulatory metabolites. How IDO deficiency affects immune responses during atherogenesis is unknown and we explored potential mechanisms in models of murine and human atherosclerosis. IDO deficiency in hypercholesterolemic ApoE(-/-) mice caused a significant increase in lesion size and surrogate markers of plaque vulnerability. No significant changes in cholesterol levels were observed but decreases in IL-10 production were found in the peripheral blood, spleen and lymph node B cells of IDO-deficient compared with IDO-competent ApoE(-/-) mice. 3,4,-Dimethoxycinnamoyl anthranilic acid (3,4-DAA), an orally active syn...

Arthritis research & therapy, 2006

We and others have reported that rheumatoid arthritis (RA) synovial T cells can activate human mo... more We and others have reported that rheumatoid arthritis (RA) synovial T cells can activate human monocytes/macrophages in a contact-dependent manner to induce the expression of inflammatory cytokines, including tumour necrosis factor alpha (TNFalpha). In the present study we demonstrate that RA synovial T cells without further activation can also induce monocyte CC and CXC chemokine production in a contact-dependent manner. The transcription factor NFkappaB is differentially involved in this process as CXC chemokines but not CC chemokines are inhibited after overexpression of IkappaBalpha, the natural inhibitor of NFkappaB. This effector function of RA synovial T cells is also shared by T cells activated with a cytokine cocktail containing IL-2, IL-6 and TNFalpha, but not T cells activated by anti-CD3 cross-linking that mimics TCR engagement. This study demonstrates for the first time that RA synovial T cells as well as cytokine-activated T cells are able to induce monocyte chemokine ...

Arthritis research, 2002

IL-10 is an anti-inflammatory cytokine produced in the joint in rheumatoid arthritis by macrophag... more IL-10 is an anti-inflammatory cytokine produced in the joint in rheumatoid arthritis by macrophages and infiltrating blood lymphocytes. Regulation of its expression is poorly understood, but previous findings have suggested that physical interactions with T cells may play a role. This report investigates signalling mechanisms involved in the production of macrophage IL-10 upon interaction with fixed, cytokine-stimulated T cells (Tck). Elutriated monocytes were differentiated to macrophages by macrophage-colony-stimulating factor (M-CSF) and co-cultured with fixed T cells chronically stimulated in a cytokine cocktail of IL-2/IL-6/tumour necrosis factor (TNF)-alpha in the presence or absence of wortmannin and LY294002, inhibitors of phosphatidylinositol 3-kinase (PI3K), or of rapamycin, an inhibitor of p70 S6-kinase (p70S6K). Spontaneous IL-10 production by rheumatoid arthritis synovial-membrane mononuclear cells (RA-SMCs) and co-cultures of rheumatoid arthritis T cells (RA-Ts) and ma...

Arthritis & Rheumatology, 2014

Objective. Functionally impaired Treg cells expressing abnormally low levels of CTLA-4 have been ... more Objective. Functionally impaired Treg cells expressing abnormally low levels of CTLA-4 have been well documented in rheumatoid arthritis (RA). However, the molecular defect underlying this reduced expression is unknown. The aims of this study were to assess the role of DNA methylation in regulating CTLA-4 expression in Treg cells isolated from RA patients and to elucidate the mechanism of their reduced suppressor function. Methods. CTLA-4 expression in Treg cells from RA patients and healthy controls was measured by quantitative polymerase chain reaction (PCR) and flow cytometry. Methylation of the CTLA-4 gene promoter was analyzed by bisulfite-specific PCR, followed by sequencing. Methylation-dependent transcriptional activity of the CTLA-4 gene promoter was measured by luciferase assay, and NF-AT binding to the CTLA-4 gene promoter was determined by chromatin immunoprecipitation. The role of CTLA-4 expression in controlling Teff cells was analyzed using an autologous mixed lymphocyte reaction. Results. Down-regulation of CTLA-4 expression in Treg cells from RA patients was caused by methylation of a previously unidentified NF-AT binding site within the CTLA-4 gene promoter. As a consequence, Treg cells were unable to induce expression and activation of the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO), which in turn resulted in a failure to activate the immunomodulatory kynurenine pathway. Conclusion. We show for the first time that epigenetic modifications contribute to defective Treg cell function in RA through an inability to activate the IDO pathway. Therefore, this study sets a precedent for investigating potential therapeutic strategies aimed at reinforcing the IDO pathway in RA patients.

Molecules, 2014

Although strong binding interactions between protein receptor and ligand do not require the parti... more Although strong binding interactions between protein receptor and ligand do not require the participation of a large number of amino acids in either site, short peptide chains are generally poor at recreating the types of protein-protein interactions which take place during cell recognition and signalling process, probably because their flexible backbones prevent the side chains from forming sufficiently rigid and stable epitopes, which can take part in binding with the desired strength and specificity. In a recently-reported study, it was shown that a proto-epitope containing F, R and S amino acids has the ability to down-regulate TNF secretion by macrophages. This paper extends these findings, putting those amino acids into a short cyclic peptide scaffold, and determining the optimal configuration required to overcome the problems of conformational instability, and give rise to molecules which have potential as therapeutic agents in human disease, such as rheumatoid arthritis.

Arthritis Research & Therapy, 2005

Chaperonins have classically been thought of as intracellular molecules involved in the correct f... more Chaperonins have classically been thought of as intracellular molecules involved in the correct folding of proteins. Their expression is upregulated during times of stress such as heat (hence their common nomenclature as heat shock proteins [HSP]), anoxia, hypoglycaemia and reactive oxygen species [1]. These are conditions found in infected tissues or in tissues with chronic inflammation such as the rheumatoid synovium. In their intracellular location they protect the cell from apoptotic death due to stress. Increasingly chaperonins have been recognised to subserve extracellular functions for which they have received the name 'chaperokines' since they bind to specific receptors on the cell surface and activate cells of the innate immune system to secrete inflammatory cytokines, chemokines and small molecular weight mediators such as prostaglandins [2]. Indeed, an early event in inflammation is cell stress/necrosis leading to the release of HSP60 and HSP70 that binds via a CD14-mediated mechanism to Toll-like receptors 2 and 4 [2] as part of the 'danger' signal [3]. The secretion of tumour necrosis factor alpha, IL-1, IL-12 and other chemokines prepares the environment for a TH1 adaptive immune response. It is now recognised that some chaperonins, such as BiP and HSP27, may activate the innate immune system to secrete anti-inflammatory cytokines, such as IL-10 [4,5] that may skew the adaptive immune response to TH2. Recent work by our group has shown that BiP can not only prevent but also treat ongoing collagen-induced arthritis in DBA/1 mice [6], suggesting that chaperonins may down modulate ongoing TH1 responses. Thus, it may be possible to suppress rheumatoid inflammation by administration of appropriate chaperonins such as BiP. Finally, chaperonins may be important system regulators determining the outcome between TH1 and Th2 immune responses. References 1. Pockley AG: Heat shock proteins as regulators of the immune response. Lancet 2003, 362:469-476. 2. Asea A: Chaperokine-induced signal transduction pathways. Exerc Immunol Rev 2003, 9:25-33. 3. Matzinger P: The danger model: a renewed sense of self. Science 2002, 296:301-305. 4. De AK, Kodys KM, Yeh BS, Miller-Graziano C: Exaggerated human monocyte IL-10 concomitant to minimal TNF-alpha induction by heatshock protein 27 (Hsp27) suggests Hsp27 is primarily an antiinflammatory stimulus.

Arthritis Research & Therapy, 2008

Background Previously we described a system whereby human peripheral blood T cells stimulated for... more Background Previously we described a system whereby human peripheral blood T cells stimulated for 8 days in a cytokine cocktail acquired effector function for contact-dependent induction of proinflammatory cytokines from monocytes. We termed these cells cytokine-activated (Tck) cells and found that the signalling pathways elicited in the responding monocytes were identical whether they were placed in contact with Tck cells or with T cells isolated from rheumatoid arthritis (RA) synovial tissue. Methods Here, using magnetic beads and fluorescenceactivated cell sorting, we extensively phenotype the Tck effector cells and conclude that effector function resides within the CD4 + CD45RO + , CCR7-, CD49d high population, and that these cells are derived from the effector memory CD4 + T cells in resting blood. Results After stimulation in culture, these cells produce a wide range of T-cell cytokines, undergo proliferation and differentiate to acquire an extensively activated phenotype resembling RA synovial T cells. Blocking antibodies against CD69, CD18, or CD49d resulted in a reduction of tumour necrosis factor-α production from monocytes stimulated with CD4 + CD45RO + Tck cells in the co-culture assay. Moreover, blockade of these ligands also resulted in inhibition of spontaneous tumour necrosis factor-α production in RA synovial mononuclear cell cultures. Conclusion Taken together, these data strengthen our understanding of T-cell effector function, highlight the multiple involvement of different cell surface ligands in cell-cell contact and, provide novel insights into the pathogenesis of inflammatory RA disease.

European Journal of Immunology, 1994

The biological activity of the pro‐inflammatory cytokine, tumor necrosis factor (TNF)‐α depends o... more The biological activity of the pro‐inflammatory cytokine, tumor necrosis factor (TNF)‐α depends on the level of TNF‐α itself, the expression of the p55 and p75 cell surface receptors for TNF on target cells and the concentrations of the natural inhibitors of TNF‐α, the soluble p55 and p75 TNF receptors (TNF‐R). Interleukin (IL)‐10 and IL‐4 are known to inhibit TNF‐α production by monocytes. We, therefore, investigated the effects of IL‐10 and IL‐4 on the cell surface expression and release of TNF‐R by human monocytes to determine whether these cytokines also indirectly modulated the biological activity of TNF‐α. Exposure to IL‐10 (1‐10 U/ml) for 24 or 48 h increased soluble p75 TNF‐R expression and concomitantly reduced surface expression of p75 TNF‐R. Further, IL‐l α‐stimulated production of TNF‐α was diminished by IL‐10 and only a small proportion of this TNF‐α was bioactive, consistent with increased production of inhibitory soluble TNF‐R. IL‐10 also induced down‐regulation of su...

The Journal of Comparative Neurology, 1996

ABSTRACT