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Walker IS, Rogerson SJ. Pathogenicity and virulence of malaria: Sticky problems and tricky solutions. Virulence 2023; 14:2150456. [PMID: 36419237 PMCID: PMC9815252 DOI: 10.1080/21505594.2022.2150456] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 11/25/2022] Open
Abstract
Infections with Plasmodium falciparum and Plasmodium vivax cause over 600,000 deaths each year, concentrated in Africa and in young children, but much of the world's population remain at risk of infection. In this article, we review the latest developments in the immunogenicity and pathogenesis of malaria, with a particular focus on P. falciparum, the leading malaria killer. Pathogenic factors include parasite-derived toxins and variant surface antigens on infected erythrocytes that mediate sequestration in the deep vasculature. Host response to parasite toxins and to variant antigens is an important determinant of disease severity. Understanding how parasites sequester, and how antibody to variant antigens could prevent sequestration, may lead to new approaches to treat and prevent disease. Difficulties in malaria diagnosis, drug resistance, and specific challenges of treating P. vivax pose challenges to malaria elimination, but vaccines and other preventive strategies may offer improved disease control.
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Affiliation(s)
- Isobel S Walker
- Department of Infectious Diseases, The University of Melbourne, The Doherty Institute, Melbourne, Australia
| | - Stephen J Rogerson
- Department of Infectious Diseases, The University of Melbourne, The Doherty Institute, Melbourne, Australia
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Nyandele JP, Kibondo UA, Issa F, Van Geertruyden JP, Warimwe G, Jongo S, Abdulla S, Olotu A. Pre-vaccination monocyte-to-lymphocyte ratio as a biomarker for the efficacy of malaria candidate vaccines: A subgroup analysis of pooled clinical trial data. PLoS One 2023; 18:e0291244. [PMID: 37708143 PMCID: PMC10501550 DOI: 10.1371/journal.pone.0291244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 08/24/2023] [Indexed: 09/16/2023] Open
Abstract
BACKGROUND Pre-vaccination monocyte-to-lymphocyte ratio was previously suggested as a marker for malaria vaccine effectiveness. We investigated the potential of this cell ratio as a marker for malaria vaccine efficacy and effectiveness. Effectiveness was investigated by using clinical malaria endpoint, and efficacy was investigated by using surrogate endpoints of Plasmodium falciparum prepatent period, parasite density, and multiplication rates in a controlled human malaria infection trial (CHMI). METHODS We evaluated the correlation between monocyte-to-lymphocyte ratio and RTS,S vaccine effectiveness using Cox regression modeling with clinical malaria as the primary endpoint. Of the 1704 participants in the RTS,S field trial, data on monocyte-to-lymphocyte ratio was available for 842 participants, of whom our analyses were restricted. We further used Spearman Correlations and Cox regression modeling to evaluate the correlation between monocyte-to-lymphocyte ratio and Whole Sporozoite malaria vaccine efficacy using the surrogate endpoints. Of the 97 participants in the controlled human malaria infection vaccine trials, hematology and parasitology information were available for 82 participants, of whom our analyses were restricted. RESULTS The unadjusted efficacy of RTS,S malaria vaccine was 54% (95% CI: 37%-66%, p <0.001). No correlation was observed between monocyte-to-lymphocyte ratio and RTS,S vaccine efficacy (Hazard Rate (HR):0.90, 95%CI:0.45-1.80; p = 0.77). The unadjusted efficacy of Whole Sporozoite malaria vaccine in the appended dataset was 17.6% (95%CI:10%-28.5%, p<0.001). No association between monocyte-to-lymphocyte ratio and the Whole Sporozoite malaria vaccine was found against either the prepatent period (HR = 1.16; 95%CI:0.51-2.62, p = 0.72), parasite density (rho = 0.004, p = 0.97) or multiplication rates (rho = 0.031, p = 0.80). CONCLUSION Monocyte-to-lymphocyte ratio alone may not be an adequate marker for malaria vaccine efficacy. Further investigations on immune correlates and underlying mechanisms of immune protection against malaria could provide a clearer explanation of the differences between those protected in comparison with those not protected against malaria by vaccination.
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Affiliation(s)
- Jane Paula Nyandele
- Global Health Institute, University of Antwerp, Antwerp, Belgium
- Ifakara Health Institute, Bagamoyo Clinical Trial Unit, Bagamoyo, Tanzania
| | - Ummi Abdul Kibondo
- Ifakara Health Institute, Bagamoyo Clinical Trial Unit, Bagamoyo, Tanzania
| | - Fatuma Issa
- Ifakara Health Institute, Bagamoyo Clinical Trial Unit, Bagamoyo, Tanzania
| | | | | | - Said Jongo
- Ifakara Health Institute, Bagamoyo Clinical Trial Unit, Bagamoyo, Tanzania
| | - Salim Abdulla
- Ifakara Health Institute, Bagamoyo Clinical Trial Unit, Bagamoyo, Tanzania
| | - Ally Olotu
- Ifakara Health Institute, Bagamoyo Clinical Trial Unit, Bagamoyo, Tanzania
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Brandão YDO, Molento MB. A Systematic Review of Apicomplexa Looking into Epigenetic Pathways and the Opportunity for Novel Therapies. Pathogens 2023; 12:pathogens12020299. [PMID: 36839571 PMCID: PMC9963874 DOI: 10.3390/pathogens12020299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 02/03/2023] [Accepted: 02/09/2023] [Indexed: 02/15/2023] Open
Abstract
Interest in host epigenetic changes during apicomplexan infections increased in the last decade, mainly due to the emergence of new therapies directed to these alterations. This review aims to carry out a bibliometric analysis of the publications related to host epigenetic changes during apicomplexan infections and to summarize the main studied pathways in this context, pointing out those that represent putative drug targets. We used four databases for the article search. After screening, 116 studies were included. The bibliometric analysis revealed that the USA and China had the highest number of relevant publications. The evaluation of the selected studies revealed that Toxoplasma gondii was considered in most of the studies, non-coding RNA was the most frequently reported epigenetic event, and host defense was the most explored pathway. These findings were reinforced by an analysis of the co-occurrence of keywords. Even though we present putative targets for repurposing epidrugs and ncRNA-based drugs in apicomplexan infections, we understand that more detailed knowledge of the hosts' epigenetic pathways is still needed before establishing a definitive drug target.
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Dobbs KR, Dent AE, Embury P, Ogolla S, Koech E, Midem D, Kazura JW. Monocyte epigenetics and innate immunity to malaria: yet another level of complexity? Int J Parasitol 2022; 52:717-720. [PMID: 35905779 DOI: 10.1016/j.ijpara.2022.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/07/2022] [Accepted: 07/10/2022] [Indexed: 12/26/2022]
Abstract
Children under the age of 5 years living in areas of moderate to high malaria transmission are highly susceptible to clinical malaria with fever that prompts treatment of blood stage infection with anti-malarial drugs. In contrast, older school age children frequently experience subclinical malaria, i.e. chronic Plasmodium falciparum parasitemia without fever or other clinical symptoms. The role of innate immune cells in regulating inflammation at a level that is sufficient to control the parasite biomass, while at the same time maintaining a disease-tolerant clinical phenotype, i.e., subclinical malaria, is not well understood. Recent studies suggest that host epigenetic mechanisms underlie the innate immune homeostasis associated with subclinical malaria. This Current Opinion article presents evidence supporting the notion that modifications of the host monocyte/macrophage epigenome regulate innate immune functions pertinent to subclinical malaria.
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Affiliation(s)
- Katherine R Dobbs
- Centre for Global Health and Diseases, Case Western Reserve University, 10900 Euclid Avenue LC:4983, Cleveland, OH 44106, USA; Division of Pediatric Infectious Diseases, Rainbow Babies and Children's Hospital, Cleveland, OH 44106, USA
| | - Arlene E Dent
- Centre for Global Health and Diseases, Case Western Reserve University, 10900 Euclid Avenue LC:4983, Cleveland, OH 44106, USA; Division of Pediatric Infectious Diseases, Rainbow Babies and Children's Hospital, Cleveland, OH 44106, USA
| | - Paula Embury
- Centre for Global Health and Diseases, Case Western Reserve University, 10900 Euclid Avenue LC:4983, Cleveland, OH 44106, USA
| | | | | | - David Midem
- Chulaimbo Sub-county Hospital, Kisumu County, Kenya
| | - James W Kazura
- Centre for Global Health and Diseases, Case Western Reserve University, 10900 Euclid Avenue LC:4983, Cleveland, OH 44106, USA.
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Huang S, van der Heijden W, Reuling IJ, Wan J, Yan Q, de Laat - Kremers RMW, Van der Ven AJ, de Groot PG, McCall M, Sauerwein RW, Bousema T, Roest M, Ninivaggi M, de Mast Q, de Laat B. Functional changes in hemostasis during asexual and sexual parasitemia in a controlled human malaria infection. PLoS One 2022; 17:e0271527. [PMID: 35839244 PMCID: PMC9286275 DOI: 10.1371/journal.pone.0271527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 07/04/2022] [Indexed: 11/18/2022] Open
Abstract
Decreased platelet count is an early phenomenon in asexual Plasmodium falciparum parasitemia, but its association with acute or long-term functional changes in platelets and coagulation is unknown. Moreover, the impact of gametocytemia on platelets and coagulation remains unclear. We investigated the changes in platelet number and function during early asexual parasitemia, gametocytemia and convalescence in 16 individuals participating in a controlled human malaria infection study, and studied its relationship with changes in total and active von Willebrand factor levels (VWF) and the coagulation system. Platelet activation and reactivity were determined by flow cytometry, and the coagulation system was assessed using different representative assays including antigen assays, activity assays and global functional assays. Platelet count was decreased during asexual blood stage infection but normalized during gametocytemia. Platelet P-selectin expression was slightly increased during asexual parasitemia, gametocytemia and at day 64. In contrast, platelet reactivity to different agonists remained unchanged, except a marked decrease in reactivity to low dose collagen-related peptide-XL. Thrombin generation and antigen assays did not show a clear activation of the coagulation during asexual parasitemia, whereas total and active VWF levels were markedly increased. During gametocytemia and on day 64, the endogenous thrombin potential, thrombin peak and velocity index were increased and prothrombin conversion and plasma prothrombin levels were decreased. We conclude that the decreased platelet count during asexual parasitemia is associated with increased active VWF levels (i.e. endothelial activation), but not platelet hyperreactivity or hypercoagulability, and that the increased platelet clearance in asexual parasitemia could cause spontaneous VWF-platelet complexes formation.
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Affiliation(s)
- Shengshi Huang
- Department of Functional Coagulation, Synapse Research Institute, Maastricht, The Netherlands
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Wouter van der Heijden
- Department of Internal Medicine, Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Isaie J. Reuling
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Jun Wan
- Department of Functional Coagulation, Synapse Research Institute, Maastricht, The Netherlands
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Qiuting Yan
- Department of Functional Coagulation, Synapse Research Institute, Maastricht, The Netherlands
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Romy M. W. de Laat - Kremers
- Department of Data Analysis and Artificial Intelligence, Synapse Research Institute, Maastricht, The Netherlands
- * E-mail:
| | - Andre J. Van der Ven
- Department of Internal Medicine, Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Philip G. de Groot
- Department of Functional Coagulation, Synapse Research Institute, Maastricht, The Netherlands
| | - Matthew McCall
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Robert W. Sauerwein
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Mark Roest
- Department of Platelet pathophysiology, Synapse Research Institute, Maastricht, The Netherlands
| | - Marisa Ninivaggi
- Department of Functional Coagulation, Synapse Research Institute, Maastricht, The Netherlands
| | - Quirijn de Mast
- Department of Internal Medicine, Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Bas de Laat
- Department of Functional Coagulation, Synapse Research Institute, Maastricht, The Netherlands
- Department of Data Analysis and Artificial Intelligence, Synapse Research Institute, Maastricht, The Netherlands
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Abstract
"The Primate Malarias" book has been a uniquely important resource for multiple generations of scientists, since its debut in 1971, and remains pertinent to the present day. Indeed, nonhuman primates (NHPs) have been instrumental for major breakthroughs in basic and pre-clinical research on malaria for over 50 years. Research involving NHPs have provided critical insights and data that have been essential for malaria research on many parasite species, drugs, vaccines, pathogenesis, and transmission, leading to improved clinical care and advancing research goals for malaria control, elimination, and eradication. Whilst most malaria scientists over the decades have been studying Plasmodium falciparum, with NHP infections, in clinical studies with humans, or using in vitro culture or rodent model systems, others have been dedicated to advancing research on Plasmodium vivax, as well as on phylogenetically related simian species, including Plasmodium cynomolgi, Plasmodium coatneyi, and Plasmodium knowlesi. In-depth study of these four phylogenetically related species over the years has spawned the design of NHP longitudinal infection strategies for gathering information about ongoing infections, which can be related to human infections. These Plasmodium-NHP infection model systems are reviewed here, with emphasis on modern systems biological approaches to studying longitudinal infections, pathogenesis, immunity, and vaccines. Recent discoveries capitalizing on NHP longitudinal infections include an advanced understanding of chronic infections, relapses, anaemia, and immune memory. With quickly emerging new technological advances, more in-depth research and mechanistic discoveries can be anticipated on these and additional critical topics, including hypnozoite biology, antigenic variation, gametocyte transmission, bone marrow dysfunction, and loss of uninfected RBCs. New strategies and insights published by the Malaria Host-Pathogen Interaction Center (MaHPIC) are recapped here along with a vision that stresses the importance of educating future experts well trained in utilizing NHP infection model systems for the pursuit of innovative, effective interventions against malaria.
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Affiliation(s)
- Mary R Galinski
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA.
- Emory Vaccine Center, Emory University, Atlanta, GA, USA.
- Emory National Primate Research Center (Yerkes National Primate Research Center), Emory University, Atlanta, GA, USA.
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Vetvicka V, Sima P, Vannucci L. Trained Immunity as an Adaptive Branch of Innate Immunity. Int J Mol Sci 2021; 22:10684. [PMID: 34639025 DOI: 10.3390/ijms221910684] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/15/2021] [Accepted: 09/16/2021] [Indexed: 12/17/2022] Open
Abstract
The concept of trained immunity has become one of the most interesting and potentially commercially and clinically relevant ideas of current immunology. Trained immunity is realized by the epigenetic reprogramming of non-immunocompetent cells, primarily monocytes/macrophages and natural killer (NK) cells, and is less specific than adaptive immunity; therefore, it may cross-protect against other infectious agents. It remains possible, however, that some of the observed changes are simply caused by increased levels of immune reactions resulting from supplementation with immunomodulators, such as glucan. In addition, the question of whether we can talk about trained immunity in cells with a life span of only few days is still unresolved.
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Ghosh S, Snehlata, Hussain S, Makkar H, Mukherjee B. Role of chromatin modulation in the establishment of protozoan parasite infection for developing targeted chemotherapeutics. Nucleus 2021; 64:401-13. [DOI: 10.1007/s13237-021-00356-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Ahmed A, Rakshit S, Adiga V, Dias M, Dwarkanath P, D'Souza G, Vyakarnam A. A century of BCG: Impact on tuberculosis control and beyond. Immunol Rev 2021; 301:98-121. [PMID: 33955564 DOI: 10.1111/imr.12968] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/13/2021] [Accepted: 03/13/2021] [Indexed: 12/14/2022]
Abstract
BCG turns 100 this year and while it might not be the perfect vaccine, it has certainly contributed significantly towards eradication and prevention of spread of tuberculosis (TB). The search for newer and better vaccines for TB is an ongoing endeavor and latest results from trials of candidate TB vaccines such as M72AS01 look promising. However, recent encouraging data from BCG revaccination trials in adults combined with studies on mucosal and intravenous routes of BCG vaccination in non-human primate models have renewed interest in BCG for TB prevention. In addition, several well-demonstrated non-specific effects of BCG, for example, prevention of viral and respiratory infections, give BCG an added advantage. Also, BCG vaccination is currently being widely tested in human clinical trials to determine whether it protects against SARS-CoV-2 infection and/or death with detailed analyses and outcomes from several ongoing trials across the world awaited. Through this review, we attempt to bring together information on various aspects of the BCG-induced immune response, its efficacy in TB control, comparison with other candidate TB vaccines and strategies to improve its efficiency including revaccination and alternate routes of administration. Finally, we discuss the future relevance of BCG use especially in light of its several heterologous benefits.
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Affiliation(s)
- Asma Ahmed
- Laboratory of Immunology of HIV-TB co-infection, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore, India
| | - Srabanti Rakshit
- Laboratory of Immunology of HIV-TB co-infection, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore, India
| | - Vasista Adiga
- Laboratory of Immunology of HIV-TB co-infection, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore, India
| | - Mary Dias
- Division of Infectious Diseases, St John's Research Institute, Bangalore, India
| | | | - George D'Souza
- Division of Infectious Diseases, St John's Research Institute, Bangalore, India.,Department of Pulmonary Medicine, St John's Medical College, Bangalore, India
| | - Annapurna Vyakarnam
- Laboratory of Immunology of HIV-TB co-infection, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore, India.,Peter Gorer Department of Immunobiology, School of Immunology and Microbial Sciences, Faculty of Life Sciences and Medicine, Guy's Hospital, King's College London, London, UK
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Rogers KJ, Vijay R, Butler NS. Anti-malarial humoral immunity: the long and short of it. Microbes Infect 2021; 23:104807. [PMID: 33684519 DOI: 10.1016/j.micinf.2021.104807] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/28/2021] [Accepted: 02/28/2021] [Indexed: 12/17/2022]
Abstract
Humoral immunity is critical for limiting Plasmodium parasite infections and the severity of malaria. Naturally acquired immunity against malaria occurs inefficiently and protection is relatively short-lived. Here we review recent advances and explore emerging hypotheses regarding the molecular and cellular pathways that regulate Plasmodium parasite-specific B cell responses and durable anti-malarial humoral immunity.
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Affiliation(s)
- Kai J Rogers
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, USA
| | - Rahul Vijay
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, USA
| | - Noah S Butler
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, USA; Interdisciplinary Graduate Program in Immunology, The University of Iowa, Iowa City, IA, USA.
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