M M Harnett

University of Glasgow, Glasgow, Scotland, United Kingdom

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Publications (136)696.62 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: We have previously reported that ES-62, a molecule secreted by the parasitic filarial nematode Acanthocheilonema viteae, protects mice from developing collagen-induced arthritis (CIA). Together with increasing evidence that worm infection may protect against autoimmune conditions, this raises the possibility that ES-62 may have therapeutic potential in rheumatoid arthritis and hence, it is important to fully understand its mechanism of action. To this end, we have established to date that ES-62 protection in CIA is associated with suppressed T helper type 1 (Th1)/Th17 responses, reduced collagen-specific IgG2a antibodies and increased interleukin-10 (IL-10) production by splenocytes. IL-10-producing regulatory B cells have been proposed to suppress pathogenic Th1/Th17 responses in CIA: interestingly therefore, although the levels of IL-10-producing B cells were decreased in the spleens of mice with CIA, ES-62 was found to restore these to the levels found in naive mice. In addition, exposure to ES-62 decreased effector B-cell, particularly plasma cell, infiltration of the joints, and such infiltrating B cells showed dramatically reduced levels of Toll-like receptor 4 and the activation markers, CD80 and CD86. Collectively, this induction of hyporesponsiveness of effector B-cell responses, in the context of the resetting of the levels of IL-10-producing B cells, is suggestive of a modulation of the balance between effector and regulatory B-cell responses that may contribute to ES-62-mediated suppression of CIA-associated inflammation and inhibition of production of pathogenic collagen-specific IgG2a antibodies.
    Immunology 03/2014; 141(3):457-66. · 3.71 Impact Factor
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    ABSTRACT: Objective. The parasitic worm-derived immunomodulator, ES-62 protects against disease in the mouse collagen-induced arthritis (CIA) model of Rheumatoid Arthritis (RA) by suppressing pathogenic IL-17 responses. The Th17-associated cytokine, IL-22 also appears to play a pathogenic role in autoimmune arthritis, particularly in promoting pro-inflammatory responses by synovial fibroblasts (SF) and osteoclastogenesis. We therefore investigated whether the protection from joint damage afforded by ES-62 also reflected suppression of IL-22. Methods. The role(s) of IL-22 were assessed by investigating the effects of neutralising anti-IL-22 antibodies and rIL-22 on pro-inflammatory cytokine production, synovial fibroblast responses and joint damage in mice with CIA, exposed to ES-62 or not. Results: Neutralisation of IL-22 during the initiation phase abrogated CIA whilst administration of rIL-22 enhanced synovial fibroblast responses and exacerbated joint pathology. By contrast, after disease onset, anti-IL-22 did not suppress progression; rather, administration of rIL-22 promoted resolution of inflammation. Consistent with these late anti-inflammatory effects, the protection afforded by ES-62 was associated with elevated levels of IL-22 in the serum and joints that reflected a desensitisation of the synovial fibroblast responses. Moreover, neutralisation of IL-22 during the late effector stage of disease prevented ES-62-mediated desensitisation of synovial fibroblast responses and protection against CIA. Conclusion: IL-22 plays a dual role in CIA, being pathogenic during the initiation phase whilst acting to resolve inflammation and joint damage during established disease. Harnessing of the tissue repair properties of IL-22 by ES-62 highlights the potential for joint-targeted therapeutic modulation of SF responses and consequent protection against bone damage in RA. © 2014 American College of Rheumatology.
    Arthritis & rheumatology (Hoboken, N.J.). 02/2014;
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    ABSTRACT: Filarial nematodes cause long-term infections in hundreds of millions of people. A significant proportion of those affected develop a number of debilitating health problems but, remarkably, such infections are often unnoticed for many years. It is well known that parasitic worms modulate, yet do not completely inhibit, host immunological pathways, promoting their survival by limiting effective immune mechanisms. Such immunoregulation largely depends on molecules released by the worms, termed excretory-secretory products (ES). One of these products is the molecule ES-62, which is actively secreted by the rodent filarial nematode Acanthocheilonema viteae. ES-62 has been shown to exert anti-inflammatory actions thorough its phosphorylcholine (PC)-containing moiety on a variety of cells of the immune system, affecting intracellular signalling pathways associated with antigen receptor- and TLR-dependent responses. We summarise here how ES-62 modulates key signal transduction elements and how such immunomodulation confers protection to animals subjected to certain experimental models of inflammatory disease. Finally, we discuss recent results showing that it is possible to synthetize small molecule analogues (SMAs) that mimic the anti-inflammatory properties of ES-62, opening an exciting new drug development field in translational medicine.
    Molecular and Biochemical Parasitology 01/2014; · 2.73 Impact Factor
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    ABSTRACT: Parasitic worms are able to survive in their mammalian host for many years due to their ability to manipulate the immune response by secreting immunomodulatory products. It is increasingly clear that, reflecting the anti-inflammatory actions of such worm-derived immunomodulators, there is an inverse correlation between helminth infection and autoimmune diseases in the developing world. As the decrease in helminth infections due to increased sanitation has correlated with an alarming increase in prevalence of such disorders in industrialised countries, this "Hygiene Hypothesis" has led to the proposal that worms and their secreted products offer a novel platform for the development of safe and effective strategies for the treatment of autoimmune disorders. Here we review the anti-inflammatory effects of one such immunomodulator, ES-62 on innate and adaptive immune responses and the mechanisms it exploits to afford protection in the murine Collagen Induced Arthritis (CIA) model of rheumatoid arthritis (RA). As its core mechanism involves targeting of IL-17 responses, which despite being pathogenic in RA are important for combating infection, we discuss how its selective targeting of IL-17 production by Th17 and γδ T cells, whilst leaving that of CD49b+ Natural Killer (NK and NK T) cells intact, reflects the ability of helminths to modulate the immune system without immunocompromising the host. Exploiting helminth immunomodulatory mechanisms therefore offers the potential for safer therapies than current biologics, such as "IL-17 blockers", that are not able to discriminate sources of IL-17 and hence present adverse effects that limit their therapeutic potential.
    Clinical & Experimental Immunology 12/2013; · 3.41 Impact Factor
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    ABSTRACT: In spite of increasing evidence that parasitic worms may protect humans from developing allergic and autoimmune diseases, and the continuing identification of defined helminth-derived immunomodulatory molecules, to date no new anti-inflammatory drugs have been developed from these organisms. We have approached this matter in a novel manner by synthesizing a library of drug-like small molecules based upon phosphorylcholine, the active moiety of the anti-inflammatory Acanthocheilonema viteae product, ES-62, which as an immunogenic protein is unsuitable for use as a drug. Following preliminary in vitro screening for inhibitory effects on relevant macrophage cytokine responses, a sulfone-containing phosphorylcholine analogue (11a) was selected for testing in an in vivo model of inflammation, collagen-induced arthritis (CIA). Testing revealed that (11a) was as effective as ES-62 in protecting DBA/1 mice from developing CIA and mirrored its mechanism of action in downregulating the TLR/IL1R transducer, MyD88. (11a) is thus a novel prototype for anti-inflammatory drug development.
    Journal of Medicinal Chemistry 11/2013; 56(24):9982-10002. · 5.61 Impact Factor
  • Article: Reply.
    William Harnett, Margaret M Harnett
    Arthritis & Rheumatology 02/2013; · 7.48 Impact Factor
  • Verica Paunovic, Margaret M Harnett
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    ABSTRACT: Rheumatoid arthritis (RA) is a chronic autoimmune disease in which imbalances in pro- and anti-inflammatory cytokines promote the induction of autoimmunity, inflammation and joint destruction. Methotrexate, the standard disease-modifying anti-rheumatic drug (DMARD), has shown a gradual loss of efficacy in a significant proportion of patients, probably due to the onset of drug resistance, and thus it was hoped that the development of biologics would revolutionise RA management. Even though biologics have improved the therapy of patients refractive to DMARDs, they require parenteral administration and may leave patients open to serious infection and cancer. Therefore, attention has also been focused on inhibitors of mitogen-activated protein kinases (MAPKs), signalling enzymes that play key roles in pathogenic cytokine production, and their downstream effector pathways, in order to create safe and effective oral drugs. This article therefore provides an overview of the structure and function of MAPKs and their role in the pathogenesis of RA as context to describing the advances in the development of specific, druggable MAPK inhibitors. Their potential as therapies in the management of RA is also discussed.
    Drugs 02/2013; · 4.63 Impact Factor
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    ABSTRACT: We previously demonstrated inhibition of ovalbumin (OVA)-induced allergic airway hyper-responsiveness in the mouse using ES-62, a phosphorylcholine-containing glycoprotein secreted by the filarial nematode, Acanthocheilonema viteae. This inhibition correlated with ES-62-induced mast cell desensitisation, although the degree to which this reflected direct targeting of mast cells remained unclear as suppression of the Th2 phenotype of the inflammatory response, as measured by eosinophilia and IL-4 levels in the lungs, was also observed. We now show that inhibition of the lung Th2 phenotype is reflected in ex vivo analyses of draining lymph node recall cultures and accompanied by a decrease in the serum levels of total and OVA-specific IgE. Moreover, ES-62 also suppresses the lung infiltration by neutrophils that is associated with severe asthma and is generally refractory to conventional anti-inflammatory therapies, including steroids. Protection against Th2-associated airway inflammation does not reflect induction of regulatory T cell (Treg) responses (there is no increased IL-10 or Foxp3 expression) but rather a switch in polarisation towards increased T-bet expression and IFNγ production. This ES-62-driven switch in the Th1/Th2 balance is accompanied by decreased IL-17 responses, a finding in line with reports that IFNγ and IL-17 are counter-regulatory. Consistent with ES-62 mediating its effects via IFNγ-mediated suppression of pathogenic Th2/Th17 responses, we found that neutralising anti-IFNγ antibodies blocked protection against airway inflammation in terms of pro-inflammatory cell infiltration, particularly by neutrophils and lung pathology. Collectively, these studies indicate that ES-62, or more likely small molecule analogues, could have therapeutic potential in asthma, in particular for those subtypes of patients (e.g. smokers, steroid-resistant) who are refractory to current treatments.
    International journal for parasitology 01/2013; · 3.39 Impact Factor
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    ABSTRACT: ES-62, an immunomodulator secreted by filarial nematodes, exhibits therapeutic potential in mouse models of allergic inflammation, at least in part by inducing the desensitisation of Fc RI-mediated mast cell responses. However, in addition to their pathogenic roles in allergic and autoimmune diseases, mast cells are important in fighting infection, wound healing, and resolving inflammation, reflecting that mast cells exhibit a phenotypic and functional plasticity. We have therefore characterised the differential functional responses to antigen (via Fc RI) and LPS and their modulation by ES-62 of the mature peritoneal-derived mast cells (PDMC; serosal) and those of the connective tissue-like mast cells (CTMC) and the mucosal-like mast cells derived from bone marrow progenitors (BMMC) as a first step to produce disease tissue-targeted therapeutics based on ES-62 action. All three mast cell populations were rendered hyporesponsive by ES-62 and whilst the mechanisms underlying such desensitisation have not been fully delineated, they reflect a downregulation of calcium and PKC signalling. ES-62 also downregulated MyD88 and PKC in mucosal-type BMMC but not PDMC, the additional signals targeted in mucosal-type BMMC likely reflecting that these cells respond to antigen and LPS by degranulation and cytokine secretion whereas PDMC predominantly respond in a degranulation-based manner.
    Journal of Parasitology Research 01/2013; 2013:961268.
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    ABSTRACT: Among many survival strategies, parasitic worms secrete molecules that modulate host immune responses. One such product, ES-62, is protective against collagen-induced arthritis (CIA), a model of rheumatoid arthritis (RA). Since interleukin-17 (IL-17) has been reported to play a pathogenic role in the development of RA, this study was undertaken to investigate whether targeting of IL-17 may explain the protection against CIA afforded by ES-62. DBA/1 mice progressively display arthritis following immunization with type II collagen. The protective effects of ES-62 were assessed by determination of cytokine levels, flow cytometric analysis of relevant cell populations, and in situ analysis of joint inflammation in mice with CIA. ES-62 was found to down-regulate IL-17 responses in mice with CIA. First, it acted to inhibit priming and polarization of IL-17 responses by targeting a complex IL-17-producing network, involving signaling between dendritic cells and γ/δ or CD4+ T cells. In addition, ES-62 directly targeted Th17 cells by down-regulating myeloid differentiation factor 88 expression to suppress responses mediated by IL-1 and Toll-like receptor ligands. Moreover, ES-62 modulated the migration of γ/δ T cells and this was reflected by direct suppression of CD44 up-regulation and, as evidenced by in situ analysis, dramatically reduced levels of IL-17-producing cells, including lymphocytes, infiltrating the joint. Finally, there was strong suppression of IL-17 production by cells resident in the joint, such as osteoclasts within the bone areas. Our findings indicate that ES-62 treatment of mice with CIA leads to unique multisite manipulation of the initiation and effector phases of the IL-17 inflammatory network. ES-62 could be exploited in the development of novel therapeutics for RA.
    Arthritis & Rheumatology 06/2012; 64(10):3168-78. · 7.48 Impact Factor
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    ABSTRACT: Negative regulation of B cell activation by cognate immune complexes plays an important homeostatic role in suppressing B cell hyperactivity and preventing consequent autoimmunity. Immune complexes co-ligate the BCR and FcγRIIB resulting in both growth arrest and apoptosis. We now show that such apoptotic signalling involves induction and activation of p53 and its target genes, the pro-apoptotic Bcl-2 family members, Bad and Bid, as well as nuclear export of p53. Collectively, these events result in destabilisation of the mitochondrial and lysosomal compartments with consequent activation and interplay of executioner caspases and endosomal-derived proteases. In addition, the upregulation of Fas and FasL with consequent activation of caspase 8-dependent death receptor signalling is required to facilitate efficient apoptosis of B cells. Consistent with this role for Fas death receptor signalling, apoptosis resulting from co-ligation of the BCR and FcγRIIB is defective in B cells from Fas-deficient MRL/MpJ-Fas(lpr) mice. As these mice develop spontaneous, immune complex-driven lupus-like glomerulonephritis, targeting this FcγRIIB-mediated apoptotic pathway may therefore have novel therapeutic implications for systemic autoimmune disease.
    Journal of Autoimmunity 05/2012; · 8.15 Impact Factor
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    ABSTRACT: ES-62 is an immunomodulatory phosphorylcholine (PC)-containing glycoprotein secreted by the rodent filarial nematode Acanthocheilonema viteae. Previously, the use of knockout mice has revealed the effects of ES-62 on macrophages and dendritic cells to be dependent on TLR4. However, it is possible that ES-62 may interact with additional proteins on the surfaces of target cells and hence that cells may vary with respect to receptor usage. In this study, we identified by molecular weight, proteins that interact with ES-62 and found differences amongst the immune system cells studied. Thus, whereas lymphocytes appear to have two major interacting proteins of ∼135 and ∼82 kDa, U937 monocytes only contain an ES-62-binding protein of the latter molecular weight. Binding to the proteins on B cells and U937 cells was blocked by PC, suggesting a critical role for this ES-62 moiety in facilitating interaction. Finally, ES-62 binding is followed by internalization in both macrophages and B cells but only in the former was absence of TLR4 found to block internalization. These findings are consistent with differences in receptor usage by ES-62 amongst different cell-types.
    Experimental Parasitology 09/2011; 132(1):97-102. · 2.15 Impact Factor
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    ABSTRACT: We aimed to investigate the effects of progesterone on gene expression and function of both myometrium and circulating leukocytes. We recruited women participating in a randomized clinical trial of progesterone to prevent preterm delivery. These participants had a twin pregnancy and were managed in 1 of 2 tertiary referral centers. Participants were treated with progesterone (90 mg vaginally) or placebo from 24 to 34 weeks of pregnancy. The outcome measures were myometrial and leukocyte gene expression and expression of cell surface markers in circulating leukocytes, all quantified ex vivo. Prolonged in vivo administration of progesterone inhibited myometrial expression of connexins 26 and 43, endothelial nitric acid synthase (eNOS), and the prostaglandin receptor EP2 ex vivo. Administration of progesterone also increased numbers of circulating neutrophils while decreasing lymphocyte proportions and decreasing neutrophil CD11b expression. The observed effects of prolonged in vivo administration of progesterone will minimize the ability of the uterus to contract as a synctium and the ability of peripheral blood leukocytes to migrate into the myometrium during parturition. We suggest that these are putative mechanisms by which progesterone might prevent preterm birth in women at high risk.
    Reproductive sciences (Thousand Oaks, Calif.) 05/2011; 18(5):435-46. · 2.31 Impact Factor
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    ABSTRACT: Sepsis is one of the most challenging health problems worldwide. Here we found that phagocytes from patients with sepsis had considerable upregulation of Toll-like receptor 4 (TLR4) and TLR2; however, shock-inducing inflammatory responses mediated by these TLRs were inhibited by ES-62, an immunomodulator secreted by the filarial nematode Acanthocheilonema viteae. ES-62 subverted TLR4 signaling to block TLR2- and TLR4-driven inflammatory responses via autophagosome-mediated downregulation of the TLR adaptor-transducer MyD88. In vivo, ES-62 protected mice against endotoxic and polymicrobial septic shock by TLR4-mediated induction of autophagy and was protective even when administered after the induction of sepsis. Given that the treatments for septic shock at present are inadequate, the autophagy-dependent mechanism of action by ES-62 might form the basis for urgently needed therapeutic intervention against this life-threatening condition.
    Nature Immunology 02/2011; 12(4):344-51. · 26.20 Impact Factor
  • Nature Immunology 01/2011; 12(8):804. · 26.20 Impact Factor
  • Mairi A McGrath, Angela M Morton, Margaret M Harnett
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    ABSTRACT: Until recently, it has not been possible to image and functionally correlate the key molecular and cellular events underpinning immunity and tolerance in the intact immune system. Certainly, the field has been revolutionized by the advent of tetramers to identify physiologically relevant specificities of T cells, and the introduction of models in which transgenic T-cell receptor and/or B-cell receptor-bearing lymphocytes are adoptively transferred into normal mice and can then be identified by clonotype-specific antibodies using flow cytometry in vitro, or immunohistochemistry ex vivo. However, these approaches do not allow for quantitative analysis of the precise anatomical, phenotypic, signaling, and functional parameters required for dissecting the development of immune responses in health and disease in vivo. Traditionally, assessment of signal transduction pathways has required biochemical or molecular biological analysis of isolated and highly purified subsets of immune system cells. Inevitably, this creates potential artifacts and does not allow identification of the key signaling events for individual cells present in their microenvironment in situ. These difficulties have now been overcome by new methodologies in cell signaling analysis that are sufficiently sensitive to detect signaling events occurring in individual cells in situ and the development of technologies such as laser scanning cytometry that provide the tools to analyze physiologically relevant interactions between molecules and cells of the innate and the adaptive immune system within their natural environmental niche in vivo.
    Methods in cell biology 01/2011; 102:231-60. · 1.44 Impact Factor
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    William Harnett, Margaret M Harnett
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    ABSTRACT: Helminths may protect humans against allergic and autoimmune diseases and, indeed, defined helminth-derived products have recently been shown to prevent the development of such inflammatory diseases in mouse models. Here, we propose that helminth-derived products not only have therapeutic potential but can also be used as unique tools for defining key molecular events in the induction of an anti-inflammatory response and, therefore, for defining new therapeutic targets.
    Nature Reviews Immunology 03/2010; 10(4):278-84. · 32.25 Impact Factor
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    ABSTRACT: ES-62 is an immunomodulatory phosphorylcholine (PC)-containing protein that is actively secreted by the rodent filarial nematode Acanthocheilonema viteae during parasitism of the vertebrate host. The net effect of ES-62¢s interaction with the immune system is the generation of an anti-inflammatory immunological phenotype. ES-62 acts to inhibit the inflammatory response by selectively targeting key MAPkinase and NF-jB signalling cassettes in a number of cells of the immune system. The activity of ES-62 is dependent on its PC moieties and therefore we tested a range of small PC-containing compounds for comparable activity to the parent molecule, in in vitro assays of inflammation employing mouse macrophages. Some of the compounds examined were indeed found to mimic the anti-inflammatory effects of ES-62 but of particular interest was the observation that some selectivity of action was demonstrated, with certain compounds differentially inhibiting distinct functional components of the inflammatory response. This raises the exciting possibility of employing such small compounds to dissect the network of key signalling pathways underlying immune cell responsiveness. In particular, we are focusing on molecular signals involved in differentially regulating inflammatory cytokines including IL- 12p40, TNF-a and IL-6 produced by macrophages.
    Immunology 01/2010; 164:131 (Suppl. 1). · 3.71 Impact Factor
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    M M Harnett, A J Melendez, W Harnett
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    ABSTRACT: The dramatic recent rise in the incidence of allergic or autoimmune inflammatory diseases in the West has been proposed to reflect the lack of appropriate priming of the immune response by infectious agents such as parasitic worms during childhood. Consistent with this, there is increasing evidence supporting an inverse relationship between worm infection and T helper type 1/17 (Th1/17)-based inflammatory disorders such as rheumatoid arthritis, inflammatory bowel disease, type 1 diabetes and multiple sclerosis. Perhaps more surprisingly, given that such worms often induce strong Th2-type immune responses, there also appears to be an inverse correlation between parasite load and atopy. These findings therefore suggest that the co-evolution of helminths with hosts, which has resulted in the ability of worms to modulate inflammatory responses to promote parasite survival, has also produced the benefit of protecting the host from pathological lesions arising from aggressive proinflammatory responses to infection or, indeed, aberrant inflammatory responses underlying autoimmune and allergic disorders. By focusing upon the properties of the filarial nematode-derived immunomodulatory molecule, ES-62, in this review we shall discuss the potential of exploiting the immunomodulatory products of parasitic worms to identify and develop novel therapeutics for inflammation.
    Clinical & Experimental Immunology 12/2009; 159(3):256-67. · 3.41 Impact Factor
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    ABSTRACT: We hypothesized that the priming and activation of maternal leukocytes in peripheral blood is a key component of parturition, and that inappropriate preterm priming of leukocytes might initiate preterm labour and delivery. The purpose of this study was to characterize peripheral blood leukocyte activation during human term and preterm labour. We obtained blood samples from pregnant women at term and preterm, both in labour and not in labour. Leukocytes were characterized according to cell subtype and cell surface marker expression. Additionally, we quantified leukocyte cytokine mRNA production, migratory ability and reactive oxygen species production of neutrophils and macrophages. We found that both term and preterm labour were associated with an increase in monocyte and neutrophil proportion or number-neutrophil migratory ability and cell surface marker expression indicating activation. Messenger RNA expression of IL-1beta and IL-8, MCP-1 and TLR-2 was also increased. We conclude that leukocytes in peripheral blood are primed in preparation for activation during term and preterm labour, and that this may contribute to the pathophysiological events of parturition. These data may lead to novel therapies and diagnostic tools for the prevention and/or diagnosis of preterm birth.
    Molecular Human Reproduction 08/2009; 15(11):713-24. · 4.54 Impact Factor

Publication Stats

3k Citations
696.62 Total Impact Points


  • 1993–2014
    • University of Glasgow
      • • Institute of Infection, Immunity and Inflammation
      • • Division of Immunology
      • • School of Medicine
      • • Institute of Cardiovascular and Medical Sciences
      • • Division of Biochemistry
      Glasgow, Scotland, United Kingdom
  • 1993–2013
    • University of Strathclyde
      • • Strathclyde Institute of Pharmacy and Biomedical Sciences
      • • Department of Immunology
      Glasgow, SCT, United Kingdom
  • 2011
    • The University of Edinburgh
      • Queen's Medical Research Institute
      Edinburgh, SCT, United Kingdom
  • 1998
    • University of Birmingham
      Birmingham, England, United Kingdom
  • 1987–1992
    • MRC National Institute for Medical Research
      Londinium, England, United Kingdom