Publications
16 results found
Najer A, Blight J, Ducker CB, et al., 2022, Potent virustatic polymer-lipid nanomimics block viral entry and inhibit malaria parasites in vivo, ACS Central Science, Vol: 8, Pages: 1238-1257, ISSN: 2374-7943
Infectious diseases continue to pose a substantial burden on global populations, requiring innovative broad-spectrum prophylactic and treatment alternatives. Here, we have designed modular synthetic polymer nanoparticles that mimic functional components of host cell membranes, yielding multivalent nanomimics that act by directly binding to varied pathogens. Nanomimic blood circulation time was prolonged by reformulating polymer–lipid hybrids. Femtomolar concentrations of the polymer nanomimics were sufficient to inhibit herpes simplex virus type 2 (HSV-2) entry into epithelial cells, while higher doses were needed against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Given their observed virustatic mode of action, the nanomimics were also tested with malaria parasite blood-stage merozoites, which lose their invasive capacity after a few minutes. Efficient inhibition of merozoite invasion of red blood cells was demonstrated both in vitro and in vivo using a preclinical rodent malaria model. We envision these nanomimics forming an adaptable platform for developing pathogen entry inhibitors and as immunomodulators, wherein nanomimic-inhibited pathogens can be secondarily targeted to sites of immune recognition.
Georgiadou A, Dunican C, Sorro-Barrio P, et al., 2022, Comparative transcriptomic analysis reveals translationally relevant processes in mouse models of malaria, eLife, Vol: 11, ISSN: 2050-084X
Recent initiatives to improve translation of findings from animal models to human disease have focussed on reproducibility but quantifying the relevance of animal models remains a challenge. Here, we use comparative transcriptomics of blood to evaluate the systemic host response and its concordance between humans with different clinical manifestations of malaria and five commonly used mouse models. Plasmodium yoelii 17XL infection of mice most closely reproduces the profile of gene expression changes seen in the major human severe malaria syndromes, accompanied by high parasite biomass, severe anemia, hyperlactatemia, and cerebral microvascular pathology. However, there is also considerable discordance of changes in gene expression between the different host species and across all models, indicating that the relevance of biological mechanisms of interest in each model should be assessed before conducting experiments. These data will aid the selection of appropriate models for translational malaria research, and the approach is generalizable to other disease models.
Georgiadou A, Dunican C, Soro-Barrio P, et al., 2021, Comparative transcriptomic analysis reveals translationally relevant processes in mouse models of malaria, Publisher: Cold Spring Harbor Laboratory
<jats:title>Abstract</jats:title><jats:p>Recent initiatives to improve translation of findings from animal models to human disease have focussed on reproducibility but quantifying the relevance of animal models remains a challenge. Here we use comparative transcriptomics of blood to evaluate the systemic host response and its concordance between humans with different clinical manifestations of malaria and five commonly used mouse models. <jats:italic>Plasmodium yoelii</jats:italic> 17XL infection of mice most closely reproduces the profile of gene expression changes seen in the major human severe malaria syndromes, accompanied by high parasite biomass, severe anemia, hyperlactatemia, and cerebral microvascular pathology. However, there is also considerable discordance of changes in gene expression between species and across all models, indicating that the relevance of biological mechanisms of interest in each model should be assessed before conducting experiments. Our data will aid selection of appropriate models for translational malaria research, and the approach is generalizable to other disease models.</jats:p>
Georgiadou A, Naidu P, Walsh S, et al., 2021, Localized release of matrix metallopeptidase 8 in fatal cerebral malaria, Clinical & Translational Immunology, Vol: 10, Pages: 1-7, ISSN: 2050-0068
ObjectiveCerebral malaria (CM) is a complication of Plasmodium falciparum malaria, in which progressive brain swelling is associated with sequestration of parasites and impaired barrier function of the cerebral microvascular endothelium. To test the hypothesis that localised release of matrix metallopeptidase 8 (MMP8) within the retina is implicated in microvascular leak in CM, we examined its expression and association with extravascular fibrinogen leak in a case–control study of post‐mortem retinal samples from 13 Malawian children who met the clinical case definition of CM during life. Cases were seven children who were found on post‐mortem examination to have ‘true‐CM’ (parasite sequestration in brain blood vessels), whilst controls were six children who had alternative causes of death (‘faux‐CM’, no parasite sequestration in blood vessels).MethodsWe used immunofluorescence microscopy and independent scoring, by two assessors blinded to the CM status, to assess MMP8 expression, extravascular fibrinogen as an indicator of vascular leak and their co‐localisation in the retinal microvasculature.ResultsIn ‘true‐CM’ subjects, MMP8 staining was invariably associated with sequestered parasites and a median of 88% (IQR = 74–91%) of capillaries showed MMP8 staining, compared with 14% (IQR = 3.8–24%) in ‘faux‐CM’ (P‐value = 0.001). 41% (IQR = 28–49%) of capillaries in ‘true‐CM’ subjects showed co‐localisation of extravascular fibrinogen leak and MMP8 staining, compared with 1.8% of capillaries in ‘faux‐CM’ (IQR = 0–3.9%, P‐value = 0.01). Vascular leak was rare in the absence of MMP8 staining.ConclusionMatrix metallopeptidase 8 was extensively expressed in retinal capillaries of Malawian children with malarial retinopathy and strongly associated with vascular leak. Our findings implicate MMP8 as a cause of the vascular endothelial barrier disruption in CM, which may precip
Katsoulis O, Georgiadou A, Cunnington A, 2021, Immunopathology of acute kidney injury in severe malaria, Frontiers in Immunology, Vol: 12, ISSN: 1664-3224
Acute kidney injury (AKI) is a common feature of severe malaria, and an independent risk factor for death. Previous research has suggested that an overactivation of the host inflammatory response is at least partly involved in mediating the kidney damage observed in P. falciparum patients with AKI, however the exact pathophysiology of AKI in severe malaria remains unknown. The purpose of this mini-review is to describe how different aspects of malaria pathology, including parasite sequestration, microvascular obstruction and extensive intravascular hemolysis, may interact with each other and contribute to the development of AKI in severe malaria, by amplifying the damaging effects of the host inflammatory response. Here, we highlight the importance of considering how the systemic effects and multi-organ involvement of malaria are intertwined with the localized effects on the kidney.
Georgiadou A, Cunnington AJ, 2019, Shedding of the vascular endothelial glycocalyx - a common pathway to severe malaria?, Clinical Infectious Diseases, Vol: 69, Pages: 1721-1723, ISSN: 1058-4838
Knackstedt S, Georgiadou A, Apel F, et al., 2019, Neutrophil extracellular traps drive inflammatory pathogenesis in malaria, Science Immunology, Vol: 4, Pages: 1-17, ISSN: 2470-9468
Neutrophils are essential innate immune cells that extrude chromatin in the form of neutrophil extracellular traps (NETs). This form of cell death has potent immunostimulatory activity. We show that heme-induced NETs are essential for malaria pathogenesis. Using patient samples and a mouse model, we define two mechanisms of NET-mediated inflammation of the vasculature: activation of emergency granulopoiesis via GCSF production, and induction of the endothelial cytoadhesion receptor ICAM-1. Soluble NET components facilitate parasite sequestration and mediate tissue destruction. We demonstrate that neutrophils have a key role in malaria immunopathology and propose inhibition of NETs as a treatment strategy in vascular infections.
Georgiadou A, Lee HJ, Walther M, et al., 2019, Modelling pathogen load dynamics to elucidate mechanistic determinants of host-Plasmodium falciparum interactions, Nature Microbiology, Vol: 4, Pages: 1592-1602, ISSN: 2058-5276
During infection, increasing pathogen load stimulates both protective and harmful aspects of the host response. The dynamics of this interaction are hard to quantify in humans, but doing so could improve understanding of mechanisms of disease and protection. We sought to model the contributions of parasite multiplication rate and host response to observed parasite load in individual subjects with Plasmodium falciparum malaria, using only data obtained at the time of clinical presentation, and then to identify their mechanistic correlates. We predicted higher parasite multiplication rates and lower host responsiveness in severe malaria cases, with severe anemia being more insidious than cerebral malaria. We predicted that parasite growth-inhibition was associated with platelet consumption, lower expression of CXCL10 and type-1 interferon-associated genes, but increased cathepsin G and matrix metallopeptidase 9 expression. We found that cathepsin G and matrix metallopeptidase 9 directly inhibit parasite invasion into erythrocytes. Parasite multiplication rate was associated with host iron availability and higher complement factor H levels, lower expression of gametocyte-associated genes but higher expression of translation-associated genes in the parasite. Our findings demonstrate the potential of using explicit modelling of pathogen load dynamics to deepen understanding of host-pathogen interactions and identify mechanistic correlates of protection.
Georgiadou A, Barrio PS, Dunican C, et al., 2019, COMPARATIVE TRANSCRIPTOMICS IDENTIFIES PHENOTYPIC SIMILARITIES BETWEEN MOUSE MODELS AND HUMAN SEVERE MALARIA, 68th Annual Meeting of the American-Society-for-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 8-8, ISSN: 0002-9637
Tabrizi MEA, Lancaster TL, Ismail TM, et al., 2018, S100P enhances the motility and invasion of human trophoblast cell lines, Scientific Reports, Vol: 8, ISSN: 2045-2322
S100P has been shown to be a marker for carcinogenesis where its expression in solid tumours correlates with metastasis and a poor patient prognosis. This protein’s role in any physiological process is, however, unknown. Here we first show that S100P is expressed both in trophoblasts in vivo as well as in some corresponding cell lines in culture. We demonstrate that S100P is predominantly expressed during the early stage of placental formation with its highest expression levels occurring during the first trimester of gestation, particularly in the invading columns and anchoring villi. Using gain or loss of function studies through overexpression or knockdown of S100P expression respectively, our work shows that S100P stimulates both cell motility and cellular invasion in different trophoblastic and first trimester EVT cell lines. Interestingly, cell invasion was seen to be more dramatically affected than cell migration. Our results suggest that S100P may be acting as an important regulator of trophoblast invasion during placentation. This finding sheds new light on a hitherto uncharacterized molecular mechanism which may, in turn, lead to the identification of novel targets that may explain why significant numbers of confirmed human pregnancies suffer complications through poor placental implantation.
Lee HJ, Georgiadou A, Walther M, et al., 2018, Integrated pathogen load and dual transcriptome analysis of systemic host-pathogen interactions in severe malaria, Science Translational Medicine, Vol: 10, Pages: 1-17, ISSN: 1946-6234
The pathogenesis of infectious diseases depends on the interaction of host and pathogen. In Plasmodium falciparum malaria, host and parasite processes can be assessed by dual RNA-sequencing of blood from infected patients. Here we performed dual transcriptome analyses on samples from 46 malaria-infected Gambian children to reveal mechanisms driving the systemic pathophysiology of severe malaria. Integrating these transcriptomic data with estimates of parasite load and detailed clinical information allowed consideration of potentially confounding effects due to differing leukocyte proportions in blood, parasite developmental stage, and whole-body pathogen load. We report hundreds of human and parasite genes differentially expressed between severe and uncomplicated malaria, with distinct profiles associated with coma, hyperlactatemia, and thrombocytopenia. High expression of neutrophil granule-related genes was consistently associated with all severe malaria phenotypes. We observed severity-associated variation in the expression of parasite genes which determine cytoadhesion to vascular endothelium, rigidity of infected erythrocytes, and parasite growth rate. Up to 99% of human differential gene expression in severe malaria was driven by differences in parasite load, whereas parasite gene expression showed little association with parasite load. Co-expression analyses revealed interactions between human and P. falciparum, with prominent co-regulation of translation genes in severe malaria between host and parasite. Multivariate analyses suggested that increased expression of granulopoiesis and interferon-γ related genes, together with inadequate suppression of type-1 interferon signalling, best explained severity of infection. These findings provide a framework for understanding the contributions of host and parasite to the pathogenesis of severe malaria and identifying targets for adjunctive therapy.
Lee HJ, Georgiadou A, Otto T, et al., 2018, Transcriptomic studies in malaria – a paradigm for investigation of systemic host-pathogen interactions, Microbiology and Molecular Biology Reviews, Vol: 82, ISSN: 1092-2172
Transcriptomics, the analysis of genome-wide RNA expression, is a common approach to investigate host and pathogen processes in infectious diseases. Technical and bioinformatic advances have permitted increasingly thorough analysis of the association of RNA expression with fundamental biology, immunity, pathogenesis, diagnosis, and prognosis. Transcriptomic approaches can now be used to realize a previously unattainable goal, simultaneous study of RNA expression in host and pathogen, in order to better understand their interactions. This exciting prospect is not without challenges, especially as focus moves from interactions in vitro under tightly controlled conditions to tissue-and systemic-level interactions in animal models and natural and experimental infections in humans. Here we review the contribution of transcriptomic studies to the understanding of malaria, a parasitic disease which has exerted a major influence on human evolution and continues to cause a huge global burden of disease. We consider malaria as a paradigm for transcriptomic assessment of systemic host-pathogen interaction in humans, because much of the direct host-pathogen interaction occurs within the blood–a readily sampled compartment of the body. We illustrate lessons learned from transcriptomic studies of malaria, and how these may guide studies of host-pathogen interaction in other infectious diseases. We propose that the potential of transcriptomic studies to improve understanding of malaria as a disease remains partly untapped because of limitations in study design rather than as a consequence of technological constraints. Further advances will require integration of transcriptomic data with analytical approaches from other scientific disciplines including epidemiology and mathematical modelling.
Bretscher MT, Georgiadou A, Lee HJ, et al., 2018, Estimating parasite load dynamics to reveal novel resistance mechanisms to human malaria, Publisher: Cold Spring Harbor Laboratory
<jats:title>Abstract</jats:title><jats:p>Improved methods are needed to identify host mechanisms which directly protect against human infectious diseases in order to develop better vaccines and therapeutics<jats:sup>1,2</jats:sup>. Pathogen load determines the outcome of many infections<jats:sup>3</jats:sup>, and is a consequence of pathogen multiplication rate, duration of the infection, and inhibition or killing of pathogen by the host (resistance). If these determinants of pathogen load could be quantified then their mechanistic correlates might be determined. In humans the timing of infection is rarely known and treatment cannot usually be withheld to monitor serial changes in pathogen load and host response. Here we present an approach to overcome this and identify potential mechanisms of resistance which control parasite load in<jats:italic>Plasmodium falciparum</jats:italic>malaria. Using a mathematical model of longitudinal infection dynamics for orientation, we made individualized estimates of parasite multiplication and growth inhibition in Gambian children at presentation with acute malaria and used whole blood RNA-sequencing to identify their correlates. We identified novel roles for secreted proteases cathepsin G and matrix metallopeptidase 9 (MMP9) as direct effector molecules which inhibit<jats:italic>P. falciparum</jats:italic>growth. Cathepsin G acts on the erythrocyte membrane, cleaving surface receptors required for parasite invasion, whilst MMP9 acts on the parasite. In contrast, the type 1 interferon response and expression of<jats:italic>CXCL10</jats:italic>(IFN-γ-inducible protein of 10 kDa, IP-10) were detrimental to control of parasite growth. Natural variation in iron status and plasma levels of complement factor H were determinants of parasite multiplication rate. Our findings demonstrate the importance of accounting for the dynamic interaction between host
Georgiadou A, Bretscher M, Lee H, et al., 2018, COMBINING RNA-SEQUENCING AND MATHEMATICAL MODELLING TO IDENTIFY MECHANISTIC CORRELATES OF PROTECTION IN MALARIA, 67th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTHM), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 27-27, ISSN: 0002-9637
Lee HJ, Walther M, Georgiadou A, et al., 2017, Integrated pathogen load and dual transcriptome analysis of systemic host-pathogen interactions in severe malaria, Publisher: Cold Spring Harbor Laboratory
<jats:title>Abstract</jats:title><jats:p>The pathogenesis of severe <jats:italic>Plasmodium falciparum</jats:italic> malaria is incompletely understood. Since the pathogenic stage of the parasite is restricted to blood, dual RNA-sequencing of host and parasite transcripts in blood can reveal their interactions at a systemic scale. Here we identify human and parasite gene expression associated with severe disease features in Gambian children. Differences in parasite load explained up to 99% of differential expression of human genes but only a third of the differential expression of parasite genes. Co-expression analyses showed a remarkable co-regulation of host and parasite genes controlling translation, and host granulopoiesis genes uniquely co-regulated and differentially expressed in severe malaria. Our results indicate that high parasite load is the proximal stimulus for severe <jats:italic>P. falciparum</jats:italic> malaria, that there is an unappreciated role for many parasite genes in determining virulence, and hint at a molecular arms-race between host and parasite to synthesise protein products.</jats:p>
Murdoch CE, Georgiadou A, Bartkeviciute M, et al., 2015, Glutaredoxin-1 Is Up-Regulated in Preeclampsia and Increases Soluble Flt-1 Expression, Publisher: SAGE PUBLICATIONS INC, Pages: 203A-204A, ISSN: 1933-7191
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