Research Guy Caljon

Abstract

Chronic inflammation plays a significant role in both the onset and progression of many diseases, including, but not limited to, cardiovascular disease, chronic infections, cancer, and inflammatory organ diseases such as COPD, NAFLD, and IBD. Furthermore, acute infections may also trigger chronic inflammation and associated long lasting sequelae. As the prevalence of these diseases is increasing in Western societies and also emerging in other regions, research in this area can have a profound societal and scientific impact. Regulated cell death, barrier dysfunction, and immune modulation are key drivers of chronic inflammatory processes (Fig. 1). There is growing evidence for a limited number of common molecular pathways underpinning the regulation of these processes, and hence for a complex interplay in their pathophysiology. In this regard, Infla-Med brings together UAntwerp's leading basic and translational researchers in these three domains to form a bench-to-bedside and back consortium. The collaboration of complementary forces has enabled scientific breakthroughs in inflammation-focused research and has proven crucial in leveraging collaborations and funding in this competitive research field. For instance, Infla-Med's first 'stage' (2016-2019) resulted in more than € 23M in awarded funding with an overall stable 45% success rate since 2016. Moreover, halfway through Infla-Med's second 'stage' (2020-2022), we have already acquired the same amount of competitive grants. In terms of excellence, Infla-Med's principle investigators have achieved remarkable success in securing large, highly competitive grants for interdisciplinary research at local (BOF-GOA/IMPULS), national (FWO-EOS, iBOF), and international (ERA.Net, Innovative Medicines Initiative, coordination of H2020-MSCA-ITN and HE-MSCA-DN projects) levels. This shows that Infla-Med has established a very high-performing synergistic research framework among its principle investigators. The next 'stage' of Infla-Med will focus on discovering additional scientific breakthroughs and increasing our involvement in leading international research networks and acquiring international excellence funding (ERC). Four key strategic decisions support these ambitious aims for Infla-Med's next stage.

Researcher(s)

• Promoter: De Meyer Guido
• Co-promoter: Caljon Guy
• Co-promoter: De Meester Ingrid
• Co-promoter: De Winter Benedicte
• Co-promoter: Francque Sven
• Co-promoter: Segers Vincent
• Co-promoter: Smet Annemieke
• Co-promoter: Vanden Berghe Tom
• Co-promoter: Van Der Veken Pieter
• Co-promoter: Wullaert Andy

Research team(s)

• Physiopharmacology (PHYSPHAR)

Project type(s)

• Research Project

Abstract

Leishmania parasites are transmitted via the bite of infected female sand flies. Inside this vector, parasites have to overcome different hurdles before they can differentiate into their metacyclic, infective form, during a process which is called metacyclogenesis. This PhD project will focus on the identification of Leishmania infantum genes that can influence the development and metacyclogenesis of parasites in the vector and hereby impact successful transmission from sand fly to vertebrate host. As both up- and downregulation of certain genes may result in enhanced transmission, two different methodologies will be applied to identify potential transmission-related genes, both in collaboration with prof. dr. Ouellette (Quebec, Canada). On the one hand, repeated infection of sand flies with an already established Leishmania COSMID library will allow for selection of more transmissible parasites that harbor those specific COSMIDs containing genes providing a benefit in the vector. Genes responsible for these observed gain-of-functions in the sand fly will be unveiled using COSMID sequencing. On the other hand, loss-of-function will be explored in parallel using a similar approach for a recently developed Leishmania CRISPR-Cas9 library. Ultimately, the identification of genes involved in transmission not only will provide useful insights on the transmission process, but it might also open doors for the development of novel transmission-blocking strategies in the future.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Hendrickx Sarah
• Fellow: Van den Broeck Lauren

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

African trypanosomiasis is a tsetse fly transmitted disease indigenous for the African continent. Millions of people in 36 sub-Saharan African countries are currently at risk of this fatal infection. The current drugs are faced with limitations of toxicity and drug resistance and to date not a single effective vaccine is available. For both vaccine development and elimination endeavours, an adequate understanding of the immunology of infection onset, disease progression and distribution of parasites to tissue sanctuary niches is crucial. Our recent work has identified the skin and lungs as overlooked tissue reservoirs. Immunological studies in mouse models unveiled the increased presence of γδ T cells in infected tissues and a profound importance of these cells in regulating parasite control and host survival. The current research initiative will investigate the complex dynamics of γδ T cells during Trypanosoma brucei infections. The project consists of three distinct work packages (WP1-3). WP1 focuses on characterizing tissue-specific γδ T cell subsets following a natural, tsetse fly-transmitted T. brucei infection, focussing on their tissue tropism and contribution to immune cell recruitment and pathology. WP2 aims to explore the molecular mechanisms underlying the immune response of γδ T cells against T. brucei parasites, including their interaction with the major variant-specific surface glycoprotein (VSG) of the parasite. In vitro studies will inform about the responsiveness and functional importance of gene expression patterns of γδ T cells to parasitic stimulation. WP3 investigates the role of γδ T cells in the development of antiparasitic adaptive immunity and post-treatment tissue repair. This research employs advanced techniques such as single-cell transcriptomics, multiparameter immunoprofiling, and histopathological examinations in unique infection models to unravel the intricate interplay between γδ T cells and T. brucei, offering unprecedented basic scientific insights and revealing opportunities for immunotherapeutic interventions against trypanosomiasis.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Baeza Garcia Alvaro
• Fellow: Jacobs Yentl

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

In the last decade, stem cells have been discovered to serve as a reservoir for many pathogenic organisms. Our recent research on visceral leishmaniasis (VL) revealed that hematopoietic stem cells (HSC) in the bone marrow underlie treatment failure and relapse. These cells exhibit a unique transcriptional signature (StemLeish) and provide an environment for the development of parasite quiescence, a metabolic state that is impervious to drug treatment. This project will build upon these cutting-edge findings in order to obtain (i) a thorough characterization of immunological processes in the HSC niche that are at the basis of treatment failure, and (ii) mechanistic insights in the possible trigger(s) of VL relapse and the particular role of Macrophage Migration Inhibitory Factor (MIF). From an applied research viewpoint, this project will (iii) establish the diagnostic value of HSC biomarkers using patient samples and (iv) install a novel drug screening platform based on the developed tools to predict and capture the risk of relapse. It is expected that this project will open new therapeutic avenues that may extend beyond leishmaniasis and be revolutionary in the precarious battle against treatment failure.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Baeza Garcia Alvaro
• Fellow: Dirkx Laura

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Despite the concept that infectious diseases are usually caused by a single pathogen, in reality, we are constantly challenged by multiple pathogens and growing evidence indicates that co-infections are a much more common event than clinically perceived. The respiratory tract is the first point of contact with airborne pathogens and the most common site for infections. Hence, human respiratory infections contribute to substantial morbidity and economic losses worldwide, resulting in approximately 2.5 million deaths each year. Recent findings have shed light on a crucial factor in the severity of respiratory infections: the role of co-infections. Considering the public health importance of respiratory infections and the scarcity of research on the impact of co-infections in the balance of immune defences, this project proposes to study the in vitro and in vivo effects of diverse parasitic, viral, and bacterial co-infections on different types of immune cellsin the lungs, and comprehensively characterize tissue local microenvironment and host-pathogen interactions. Additionally, we will investigate the immunomodulatory effects of protozoan infections on vaccines and chemotherapy treatments and their impact on the protection against targeted pathogens. Objectives include: elucidate the molecular mechanisms underlying immunological responses in the lungs and the susceptibility to co-infections; investigate altered immune responses of vaccines and the changes in the response to co-infection after chemotherapy of the primary infection. In the end, this study will allow deeper understanding of respiratory co infections that could pave the way for the development of improved diagnostic and prognostic techniques, as well as the potential for proposing supportive treatments and vaccines. Notwithstanding, the development of this project will open up new avenues for future co infection research and propel the fellow towards establishment as a successful independent researcher.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Cos Paul
• Co-promoter: Delputte Peter
• Fellow: Araujo Sergio

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Major knowledge gaps exist in the frequent treatment failures during visceral leishmaniasis (VL). Our cutting-edge research has identified the bone marrow as a sanctuary tissue where parasites survive treatment. Combination of large-scale drug screening and immunophenotyping identified stem cells as highly susceptible host cells. These cells exhibit the transcriptional "StemLeish" program and provide an environment for the development of parasite quiescence, a metabolic state that is impervious to drug treatment. Our recently completed genome-wide transcriptomics studies provide unprecedented insights in quiescence and lead to the identification of various potential drivers of entry into a dormant state. Based on the collective multidisciplinary expertise of LMPH (UA) and CMIM (VUB-VIB), this project will provide detailed information about the host- and parasite-related factors underlying relapse by (i) obtaining fundamental compositional, functional, single cell and spatial insights in the immunopathology of bone marrow infection, (ii) deciphering the role of Stemleish genes in infection and in stimulation of parasite quiescence (iii) identifying parasite driver genes that trigger the development of quiescence and (iv) explore the therapeutic impact of pharmacological inhibition of major Stemleish gene products and related pathways. It is expected that in-depth molecular understanding of the stem cell niche and parasite quiescence will be revolutionary for VL treatment.

Researcher(s)

• Promoter: Caljon Guy

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

African trypanosomiasis is a tsetse fly transmitted disease indigenous for the African continent. Millions of people in 36 sub-Saharan African countries are currently at risk of this fatal infection. The current drugs are faced with limitations of toxicity and drug resistance and to date not a single effective vaccine is available. For both vaccine development and elimination endeavours, an adequate understanding of the immunology of infection onset, disease progression and distribution of parasites to tissue sanctuary niches is crucial. Our recent work has identified the skin and lungs as overlooked tissue reservoirs. Although they are sites of strong parasite proliferation, the limited organ-specific pathology has led us to overlook their importance in disease establishment and parasite transmission. Asymptomatic individuals who remain undiagnosed may pose a significant constraint for disease control. Understanding both colonization of skin and lungs as major reservoir tissues and specific parasite adaptations, will support the identification of parasite- or host-specific markers for diagnosis and increase our insight into the immunological basis of increased susceptibility to secondary pulmonary infections. Hence, we will use unbiased approaches linking parasite and tissue transcriptomes and evaluate the use of breathomics as novel diagnostic method.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Lamote Kevin
• Fellow: Mabille Dorien

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Visceral leishmaniasis is a major neglected lethal parasitic disease for which treatment options are scarce and toxicity, resistance and post-treatment relapse are common. No human vaccine is currently available and parasite quiescence is completely overlooked in the development of novel vaccination strategies. Our cutting-edge research has recently identified stem cells in the bone marrow as a sanctuary site where parasites can hide and survive drug treatment by transitioning to a quiescent state. Transcriptional profiling of quiescent and non-quiescent parasites provided differential genes, uniquely expressed during quiescence, that constitute attractive therapeutic vaccine antigen candidates. This project will provide unprecedented information about host-pathogen interactions and explore vaccination strategies to prevent relapse by: (i) obtaining essential data on antigenic presentation properties of Leishmania-infected stem cells, (ii) editing parasitic quiescence genes and selecting single domain antibodies (sdAbs) against quiescence gene products, and (iii) exploring immunity to quiescence genes during infection and following immunization. Taken together, it is expected that in-depth understanding of parasitic quiescence and corresponding antigenic/immunogenic properties will be revolutionary for the development of novel therapeutic vaccination strategies that can be incorporated with drug treatment to prevent relapse.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Sterckx Yann
• Fellow: Present Cassandra

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Malaria, caused by Plasmodium parasites, is one of the 'Big Three' infectious diseases, together with HIV and TB. Each year more than 200 million cases of the disease are documented, including more than half a million deaths (>76% of the deceased are children under the age of five). Problems are worsened due to low-efficacy vaccines, drug-resistant parasites and the (re-)emergence of the disease around the globe. This clearly indicates that novel intervention strategies are still direly needed. Antibodies (Abs) are potent tools for parasite neutralisation. Besides conventional Abs, the natural immune repertoire of mammals contains so-called unconventional diversification strategies, which extend the coverage of antigen space. Interestingly, unconventional Abs appear to excel in neutralising highly sophisticated pathogens. Camelid single-domain Abs (sdAbs) are prime examples of such unconventional Ab fragments. Extensive knowledge on the camelid sdAb structure-function relationship enables the construction of highly diverse synthetic libraries that offer several advantages over immune libraries obtained through immunisation. This project aims to harness the potential of synthetic sdAb libraries with unconventional diversification strategies to tackle the malaria sporozoite through an interdisciplinary research approach combining molecular, structural, and parasitological methods.

Researcher(s)

• Promoter: Sterckx Yann
• Co-promoter: Caljon Guy
• Fellow: De Vocht Line

Research team(s)

• Medical Biochemistry

Project type(s)

• Research Project

Abstract

Infectious disease research (including diagnostic, preventative and therapeutic development) has been a longstanding spearhead initiative of the University of Antwerp. This is driven by a vibrant research community, which is embedded in a larger "infectious disease ecosystem" in Flanders. A significant portion of these efforts is specifically devoted towards tackling protozoan parasites, a group of unicellular eukaryotes that affect the livelihoods of billions of people and their livestock around the world. Protozoan parasites cause some of the most daunting infectious diseases to have burdened humankind in past and present times (e.g., malaria, leishmaniasis, trypanosomiasis). These diseases are hallmarked by a significant mortality and a high morbidity, thereby severely impacting the quality of life and socio-economic status of those affected. Protozoan parasites are currently endemic in large parts of the world (over 100 countries ranging from the Americas to Southeast Asia) and pose a global risk due to human migration, climate change and an expanded distribution of the insect vectors that enable parasite transmission. Consequently, even currently unaffected areas (including the Western world) are confronted with disease (re-)emergence. Hence, the current burden and pandemic potential of protozoan parasites advocate the urgency and necessity to invest in tools that enable swift parasite detection and control. Some of the most potent and promising tools employed by humans in the battle against their pathogens are obtained from other animal species. A striking example is provided by the Belgian discovery of a peculiar antibody subset that naturally occurs in camelids (e.g., alpacas, llamas, camels, and dromedaries). In these antibodies, antigen recognition is mediated by a single domain, which is why it is often referred to as a "single-domain antibody" (sdAb). During the past decades it has been recognised that sdAbs possess many remarkable properties that render them highly suitable for discovery, application, and valorisation in life sciences (including diagnostics and therapeutics). These very same properties also make them unique and potent tools for pandemic preparedness and responsiveness. Literature and market analyses reveal that sdAbs remain largely under-utilised in the battle against protozoan parasites. Consequently, the application of sdAbs in the field of human and veterinary parasitology represents uncharted territory. This project aims to harness the highly complementary expertise at UAntwerp with regards to the generation and application of sdAbs in the field of parasitology to establish PREPARAS, a hybrid platform for the generation and identification of anti-parasite sdAbs via both immune and synthetic libraries. This will generate a fruitful synergy between research, application development, and valorisation given i) the veterinary expertise and strong research focus of the participating laboratories on protozoan parasite biology, ii) the unique opportunity of exploiting a hybrid platform for sdAb generation, and iii) the potential of sdAbs to address scientifical, medical and market-driven needs. Hence, PREPARAS will provide in-house access to unique research and development tools to remain at the forefront in the global battle against protozoan parasites of human and veterinary importance.

Researcher(s)

• Promoter: Sterckx Yann
• Co-promoter: Caljon Guy
• Co-promoter: Leroy Jo

Research team(s)

• Medical Biochemistry

Project type(s)

• Research Project

Abstract

Visceral leishmaniasis (VL) is a lethal parasitic disease facing a rise of treatment failures with current drugs. Major knowledge gaps exist in the basis of treatment failure, representing an essential constraint in the development of long-term effective drugs. Our cutting-edge research has recently identified the bone marrow as a sanctuary site where parasites can hide and survive drug treatment. Combination of large-scale in vivo drug screening and immunophenotyping identified stem cells as highly susceptible host cells. These cells exhibit a unique transcriptional "StemLeish" program and provide an environment for the development of parasite quiescence, a metabolic state that enables survival of drug treatment. This project will provide unprecedented information about the host- and parasite-factors underlying relapse by (i) obtaining essential data on the infection and spreading potential of quiescence-associated traits, (ii) deciphering the role of Stemleish genes in stem cell sanctuary and in stimulation of parasite quiescence, with identification of parasite driver/marker genes, and (iii) exploring the therapeutic and diagnostic applications of these novel targets and biomarkers. Taken together, it is expected that in-depth understanding of the molecular basis of stem cells as a parasite niche will be revolutionary for VL treatment and will generate potential diagnostic/prognostic tools that incorporate host sanctuary properties and parasite quiescence features.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Dirkx Laura
• Fellow: Nicolaes Yasmine

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

The Nlrp3 inflammasome is a protein complex that responds to microbial structures leading to the activation of a protease called caspase-1 that induces a form of cell death termed pyroptosis. This cell death mode facilitates secretion of the pro-inflammatory cytokines IL-1β and IL-18 that contribute to mounting efficient inflammatory responses against infections. Leishmaniasis is a major neglected parasitic disease caused by Leishmania species that can lead to a broad range of clinical manifestations ranging from cutaneous and mucocutaneous inflammation to a lethal visceral leishmaniasis (VL). Mouse model observations demonstrated an involvement of Nlrp3 inflammasome signalling in cutaneous leishmaniasis, and patient observations showed that the inflammasome-generated cytokines IL-1β and IL-18 correlate with VL severity. However, the effect of downstream Nlrp3-induced pyroptosis on the more severe VL disease has not been investigated. Moreover, recent observations showed that the ability of VL parasites display different infection kinetics in different cell types and at different stages of the infection, suggesting that pyroptosis could represent one of the intracellular host defence mechanisms responsible for determining parasite survival and spreading. Therefore, in this project we aim to reveal how Nlrp3-induced pyroptosis affects visceral leishmaniasis in mice. More specifically, we will aim to reveal in which cell types VL parasites induce pyroptosis as well as to reveal the in vivo function of pyroptosis during a model of treatment relapse VL in mice. In addition, we will aim to reveal how pyroptosis correlates with the in vivo infection kinetics of VL parasites during pathogenesis, and how this form of cell death in turn impacts on the parasite. On the long term, this project might facilitate designing better cell type and disease stage specific VL treatments. In addition, mapping the capacities of different myeloid cell types for undergoing pyroptosis during VL will generate general knowledge with implications beyond parasitic infections such as in other types of infections and in inflammatory diseases associated with inflammasome activation.

Researcher(s)

• Promoter: Wullaert Andy
• Co-promoter: Caljon Guy
• Fellow: Mortelmans Silke

Research team(s)

• Cell death signaling (CDS)

Project type(s)

• Research Project

Abstract

The collaboration with DNDi is aimed at providing a solid proof-of-concept in in vitro and animal models for the treatment of leishmaniasis with current (pre-)clinical leads and/or with a combination of leads and current reference antileishmanial drugs. Services to support DNDi discovery and development projects will cover in vitro monotherapy profiling against a panel of (resistant) strains, in vivo evaluation in mouse and/or hamster efficacy models including both monotherapy and combination therapy with PK analysis, evaluation of antiparasitic killing kinetics, and evaluation in immunocompromised animal models.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Chemotherapy is a cornerstone in the battle against leishmaniasis, a neglected tropical disease caused by Leishmania parasites that affects millions worldwide. In addition, currently unaffected areas are confronted with the (re-)emergence of the disease. Unfortunately, an alarming number of reports are describing treatment failure with currently available drugs, which can be traced back to three main mechanisms employed by the parasite to cope with the exposure to chemotherapy: drug resistance, hiding in so-called "sanctuary sites" and parasite quiescence. Given that the current number of anti-leishmanial treatment options is limited and that those available are unsatisfactory, there is a dire need for the discovery of novel compounds, preferably with yet unexplored modes of action. In this quest, DNDI-6690 has been identified as a promising lead. While the molecular target of this compound has been identified, many aspects for the molecular basis of the anti-leishmanial activity of DNDI-6690 remain enigmatic. First, a biophysical and structural characterisation of the target – DNDI-6690 complex is still lacking. Second, the breadth of the compound's activity within the Leishmania genus has not been fully explored. Finally, the link between the action of DNDI-6690 and parasite quiescence remains to be investigated. Given the promising nature of DNDI-6690 and the dire need for novel tools to combat leishmaniasis, this warrants further investigation.

Researcher(s)

• Promoter: Sterckx Yann
• Co-promoter: Caljon Guy
• Fellow: Wuyts Ellen

Research team(s)

• Medical Biochemistry

Project website

Project type(s)

• Research Project

Abstract

Background: Neglected tropical diseases (NTDs) encompass a wide range of communicable diseases that are common in tropical and subtropical regions and affect more than 1 billion people worldwide. NTDs typically have a major impact on low-income countries and pose a major health threat in both developed and developing countries. A typical feature is high morbidity, which has a serious impact on quality of life, social integration, mental health and economic productivity and status. The situation is further complicated by globalization, human migration, climate change and the altered distribution of NTD-transmitting vectors (blood feeding arthropods such as mosquitoes, flies and ticks). As a result, even currently unaffected areas (including Europe) are facing the (re)emergence of NTDs and are at increased risk of becoming endemic. The World Health Organization (WHO) and the goals set out in the Millennium Declaration underline that monitoring NTDs not only has a direct medical impact but is also a strategy for combating poverty. That is why the WHO has listed 20 priority NTDs in the interest of global health and well-being. Two of these, leishmaniasis and human African trypanosomiasis (HAT, sleeping sickness) are at the heart of the research in my research group. Objectives: The parasitology research team I lead at LMPH (LMPH-PAR) uses a two-pronged approach to address NTDs, with an emphasis on drug discovery with novel mechanisms of action and immunoparasitology research. The main aim is to deliver key innovative elements with high translational potential to the next generation of therapies, diagnostics and vaccines using complementary and multidisciplinary approaches. In addition, there are still large knowledge gaps in the highly efficient transmission of parasites by their respective insect vectors, tsetse flies and sand flies. The primary objectives are (i) to understand the immunoparasitological basis of early infection after insect bite, (ii) identification of advanced anti-parasitic lead compounds, (iii) to determine the mechanisms of action of the most advanced leads with an emphasis on deconvolution of the targets, (iv) understanding the basis of treatment failure and the spread of resistance and (v) strategic exploration of innovative vaccines and diagnostic modalities to identify novel vaccine targets and obtain reliable cure tests.

Researcher(s)

• Promoter: Caljon Guy
• Fellow: Caljon Guy

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project website

Project type(s)

• Research Project

Abstract

Despite a global distribution of Leishmaniasis and 1.5 to 2 million new cases annually, no effective human vaccines are available and treatment failure with current drugs is on the rise. Mast cells (MCs) are immune sentinels in the skin that are amongst the first to contact the Leishmania parasite following a sand fly bite. These cells play major roles in orchestrating early inflammatory responses, regulating vascular permeability and influencing immunity development in lymph nodes. Despite seminal work in mosquito-transmitted viral diseases, MCs remain underexplored as target cell during parasitic infections. Combining the strengths in immunology, parasitology, transcriptomics and biostatistics, the role of MCs will be assessed in natural Leishmania infection. Combining digital transcriptomic data from large human cohorts and experimental mouse infections, will enable detailed cross-species and multi-tissue insights into MC responses across the whole clinical spectrum of leishmaniasis. Using human MCs derived from progenitors in donor blood, a battery of cellular activation markers and specific silencing of MC gene expression using an in-house, cutting-edge method will enable unprecedented mechanistic insights in the interaction with infectious agents, i.e. Leishmania spp. parasites. This may provide new biomarkers for clinical follow-up as well as novel therapeutic targets that will be explored in the appropriate animal models of leishmaniasis initiated by a sand fly bite.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Ebo Didier

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Plasmodium falciparum parasites (causing more than 500,000 deaths each year) are transmitted from human to human via gametocytes (i.e. the sexual and only transmissible parasite stages) which are taken up by mosquitoes during a blood meal. A small fraction of parasites convert to gametocytes at every life cycle; nevertheless our understanding of which factors influence this decision and increase parasite conversion to gametocytes is poorly understood. In this project, we aim to investigate whether host and parasite genetics alter gametocyte conversion and if host anti-gametocyte immunity modifies gametocyte carriage (i.e. the gametocytes burden in peripheral blood) . We will use recently developed in vitro conversion assays and establish a novel ex vivo conversion assay, to measure the effect of host and parasite genetics on gametocyte conversion within P. falciparum transgenic lines as well as in field isolates. Furthermore, the potential contribution of host immune responses to the carriage of circulating stage V gametocytes will be assessed with immunological assays. We expect that the outcomes of this project will guide the development of new targets and tools (e.g. drugs and vaccines against the transmissible stages of the parasite) and will provide the knowledge to improve malaria transmission-blocking interventions.

Researcher(s)

• Promoter: Caljon Guy
• Fellow: Drissi El Boukili Yasmina

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

The Research Consortium of Excellence Infla-Med combines multidisciplinary expertise of eight research groups from two faculties to perform fundamental and translational research on inflammation, including: inflammatory gastrointestinal, cardiovascular, lung and kidney disorders, sepsis and allergies, as well as parasitic diseases, thereby focusing on specific inflammatory cell populations, including monocytes/macrophages, mast cells, basophils and lymphocytes. The approach of the Infla-Med consortium is twofold. Firstly, fundamental studies are performed to unravel the pathophysiological mechanisms underlying inflammatory conditions in order to enable more rational, targeted and effective intervention strategies. Secondly, Infla-Med aims to identify and validate novel therapeutic targets by screening chemical compounds in early drug discovery studies and by using an extensive platform of in vitro assays and in vivo models. The close collaboration with the Antwerp University Hospital (UZA) creates the opportunity to directly translate and clinically validate experimental findings. Thereby, Infla-Med contributes to two Frontline Research Domains of the University of Antwerp: 'Drug Discovery and Development' and 'Infectious Diseases'. Over the past four years, the multidisciplinary collaborations within Infla-Med have proven to be very successful and productive. By integrating the Infla-Med unique expertise on drug development, in vitro assays and clinically relevant animal models (validated with human samples), significant competitive funding has been acquired at European, national and UAntwerp levels with a success rate of more than 45%, which is far above the (inter)national average. Noteworthy, several Infla-Med projects have also made the transition towards valorization, demonstrating that Infla-Med results obtained from both fundamental research and well-designed preclinical studies can successfully be translated into clinical trials.

Researcher(s)

• Promoter: De Meyer Guido
• Co-promoter: Augustyns Koen
• Co-promoter: Caljon Guy
• Co-promoter: De Meester Ingrid
• Co-promoter: De Winter Benedicte
• Co-promoter: Ebo Didier
• Co-promoter: Heidbuchel Hein
• Co-promoter: Vanden Berghe Tom

Research team(s)

• Physiopharmacology (PHYSPHAR)

Project website

Project type(s)

• Research Project

Abstract

In the frame of a fee-for-service agreement, UAntwerpen shall perform certain services namely 'Evaluation of the antileishmanial potency of an active pharmaceutical ingredient in a hamster model of visceral leishmaniasis'.

Researcher(s)

• Promoter: Caljon Guy

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Human respiratory infections lead to a spectrum of respiratory symptoms and variable disease severity, contributing to substantial morbidity, mortality and economic losses worldwide. Respiratory pathogens can spread easily in the population and are specifically prone to cause large scale outbreaks, epidemics and even pandemics. While such pandemics have devastating impact on human health and cause major socio-economic disruptions, the annual burden of respiratory infections such as Respiratory Syncytial Virus (RSV), Mycobacterium tuberculosis and Streptococcus pneumoniae is also substantial. Respiratory infections are worldwide the number one cause of death in children below five years of age, with ~650.000 annual deaths. The disease burden however goes beyond this staggering number, with an overall effect on morbidity and mortality in the general population worldwide (~2.5 million deaths annually). Of particular interest, it has become very clear that severe disease upon respiratory infections not only depends on one particular pathogen, but also depends on other previous or simultaneous co-infections. The importance and impact of co-infection are however not yet fully clear. Therefore, there is an urgent need to enhance our understanding of host-pathogen interactions at the lung (immune) interface and to develop clinically relevant animal models. Laboratory animal studies are a cornerstone of basic research and the development of novel prophylactic, diagnostic and therapeutic modalities. However, the development of suitable infection models can be notoriously daunting, often resulting in very narrow assay windows due to rapid pathogen clearance or early mortality of the host. The research teams involved in this challenge have longstanding expertise with infection models, both in vitro and in rodents. Three PIs focus their research on parasitic (prof. Caljon), viral (Prof. Delputte) and bacterial infections (Prof. Cos) to gain understanding of protective innate and adaptive immune responses, and of (immune) pathology. A recent study in which LMPH was involved demonstrated that some lung bacteria have an immune modulatory role in chronic respiratory diseases (Rigauts et al., Eur. Resp. J., 2022). Very recent parasitological observations show that African trypanosomes rapidly and permanently colonize the lung tissue with substantial changes in the immunological repertoire (reductions in B cells and eosinophils) but without overt respiratory dysfunction or pathology. Surprisingly, RSV challenge revealed a higher susceptibility with an enhanced and sustained viral replication, hinting at complex in vivo interactions that cannot be modelled in vitro (Mabille et al., Nat. Commun., pending acceptance). Exploiting the expertise with parasitic, viral and bacterial infections at LMPH, the established high-end platforms for evaluating lung function and immunological correlates and initiatives of biobanking, this challenge aims to functionally and immunologically characterize pulmonary infections and co-infections of parasitic, viral and bacterial origin. This will provide invaluable information on virulence and pathogenicity of selected strains from in-house collections, establishment of in vivo read-out assays and immunological correlates of induced pathology. Besides progressing basic scientific insights in host-pathogen interactions, the applications are numerous including the development and evaluation of diagnostics and medicinal compounds.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Cos Paul
• Co-promoter: Delputte Peter
• Fellow: Araujo Sergio

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Dipeptidyl peptidase 9 (DPP9) is a cytosolic serine protease. The enzyme has lately attracted extensive international research attention, because of its recently discovered role in inflammatory cell death (pyroptosis). Among other things, it has been demonstrated that inhibition or knock-down of DPP9 leads to induction of pyroptosis in acute myeloid leukemia cells. Also in other oncology domains, DPP9 inhibition is currently investigated as a pyroptosis induction mechanism. In this form of programmed cell death, cancer cells are not only killed off, but they also release proteins that cause a strong, local upregulation of the innate immune system. This immunotherapeutic effect is generally seen as highly promising. To date, however, no clinically useful and selective DPP9 inhibitors have been reported. Very recently, however, the applicants discovered a series of low nanomolar small molecule DPP9 inhibitors with unprecedented selectivities toward all enzymes that are related to DPP9. Given the properties of these compounds and their significant valorisation potential, a patent application was submitted during June 2022. This IOF-POC project is expected to generate scientific data that should corroborate further the submitted patent application. In addition, these data should convince industrial partners to take a licence on the submitted patent. Next to new chemical data, this project application covers pharmacokinetic, pharmacodynamic and in vitro phenotypic research toward new inhibitors.

Researcher(s)

• Promoter: Van Der Veken Pieter
• Co-promoter: Caljon Guy
• Co-promoter: De Meester Ingrid

Research team(s)

• Medicinal Chemistry (UAMC)

Project type(s)

• Research Project

Abstract

The current application envisages extending the infectious disease and inflammation research and drug discovery platforms at the University of Antwerp to accommodate highly flexible and versatile live cell imaging and biochemical read-outs with a possibility to upgrade from median to high throughput. The apparatus will be embedded in a high-end immunoprofiling platform and BSL-2 environment at the Laboratory of Microbiology, Parasitology and Hygiene (LMPH) with biosafety approvals for basic research on infection with microbial pathogens. The TECAN SPARK Cyto 600 is a highly versatile multimodal plate reader that enables cellular and in situ molecular assays in controlled O2/CO2, humidity cassette and temperature regulation environments with real-time absorbance, fluorescence and luminescence measurements. Three different optical measurement options exist by using filters, monochromators or fusion optics which eliminates the compromise between sensitivity and flexibility. The unique lid-lifting function enables substrate addition or immune cell priming through the included 2-channel injector. SPARK Cyto 600 is equipped with 2×, 4× and 10× objective lenses and a CMOS camera to enable live cell imaging. In addition to bright field imaging, fluorescence imaging is possible in 4 optical channels with capability of Time-Resolved Fluorescence (TRF) and Fluorescence Resonance Energy Transfer (FRET). An additional asset is the compatibility with bead-based proximity assays using Alpha Technology with optimized integrated filters and laser-based excitation. While all known competitors limit live cell imaging systems to bright field and fluorescence measurements, the SPARK Cyto 600 also allows for real-time detection of glow and flash luminescence signals and Bioluminescence Resonance Energy Transfer (BRET) applications to enable sensitive real-time follow-up of protein-protein interactions in cells. Given the high versatility and pressing need for such equipment for infection and inflammatory disease research, this unique apparatus will allow real-time imaging of cellular as well as molecular events in controlled conditions. This new infrastructure will therefore boost research of many research groups at the University of Antwerp and will contribute to fundamental insights at the cellular and molecular level as well as to the development of novel therapeutics and diagnostics.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Augustyns Koen
• Co-promoter: Sterckx Yann
• Co-promoter: Vanden Berghe Wim
• Co-promoter: Wullaert Andy

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

The predominant Leishmania transmission route is through a bite of female sand flies. However, studies conducted on dogs and case reports from humans suggest that immunocompromised visceral leishmaniasis (VL) patients might also be able to transmit Leishmania parasites through sexual intercourse. We aim to initiate an unprecedented pilot study to gather preliminary evidence on parasite presence and persistence in the semen of male VL-HIV patients and its underlying pathophysiology. First, we will perform a qualitative study to gather perspectives of health care workers and patients regarding semen sample collection to develop appropriate operating procedures in suitable conditions. Second, 15 VL-HIV patients will be recruited, clinically examined and viable Leishmania parasites will be measured in semen samples prior to and post treatment. The immunological and histopathological impact of semen parasite infiltration will be assessed in detail in an immune-competent and -compromised hamster model and by measuring corresponding inflammatory and oxidative stress markers in patients' semen. If parasite infiltration and persistence can be shown, this proof-of-concept study in humans and rodent models would significantly increase our competitiveness to apply for a more comprehensive study on the prevalence of sexual transmission and impact on fertility.

Researcher(s)

• Promoter: Caljon Guy

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Crucial insights in cell and developmental biology have been gained by virtue of live cell imaging technology. Along with a growing complexity of cellular models and the finesse with which they can be genetically engineered, comes a demand for more advanced microscopy. In brief, modern comprehensive cell systems research (cellomics) requires light-efficient, intelligent and interactive imaging modalities. To address this shared need, our consortium has identified a state-of-the art platform that allows ultrafast, yet minimally invasive imaging of small to medium-sized biological samples (from single cells to organoids) at high resolution, so as to capture dynamic events that range in timescale from voltage fluctuations to successive cell divisions. To only focus on those events that are truly of interest, and thereby boost throughput, the system is equipped with online image recognition capabilities. Finally, to allow targeted perturbations such as local damage induction or optogenetic switching, small regions can be selectively illuminated in the field of view. With this level of control, it will become possible to interrogate (sub-)cellular processes with unprecedented detail. The platform readily finds applications in diverse frontline research fields including neuroscience, cardiovascular research and infectious diseases, rendering it an indispensable asset for the applicants, the microscopy core facility and the University of Antwerp.

Researcher(s)

• Promoter: De Vos Winnok
• Co-promoter: Caljon Guy
• Co-promoter: De Meyer Guido
• Co-promoter: Jordanova Albena
• Co-promoter: Rademakers Rosa
• Co-promoter: Timmerman Vincent
• Co-promoter: Timmermans Jean-Pierre
• Co-promoter: Vissenberg Kris
• Co-promoter: Weckhuysen Sarah

Research team(s)

• Laboratory of cell biology and histology

Project type(s)

• Research Project

Abstract

Within ongoing collaborative research with the Lab. of Medicinal Chemistry (UGent), a series of novel nucleoside analogues was identified to have potent and selective in vitro activity against African Trypanosomes, which was also confirmed in vivo in an acute and a chronic mouse model of Trypanosoma brucei. A basic dataset supporting early preclinical exploration is already available: oral availability, metabolic stability, blood-brain barrier passage, cidal and curative potential and mechanism of action. Project valorization potential must currently be situated in the veterinary application area in view of its economical and societal impact, and much less in the human application. In order to formally upgrade this project to 'drug development candidate' status, additional preclinical exploration is required to reach a go / no-go decision and trigger a commitment of a committed public-private partnership (GALVmed). In line with their preferred target product profile (TPP), the proposed research will involve in vitro and in vivo pharmacology extended to the animal trypanosome species, absorption and elimination pharmacokinetics after oral and parenteral (single dose) administration, in vitro metabolic half-life in the target animal species (cattle, horse), genotoxicity (Ames test) and short term (2w) repeated-dose toxicity in mice.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

There is growing conviction that certain parasites successfully initiate infection in the skin by specifically targeting and co-opting immune cells present or recruited to the dermis following inoculation by their arthropod vector. One such pathogen is the protozoan parasite Trypanosoma brucei which causes sleeping sickness and is inoculated by the tsetse fly. These inoculated parasites are peculiarly infective despite the rapid recruitment of activated innate immune cells at the inoculation site, revealing that the parasite has evolved powerful mechanisms to either evade or overcome the host's vigorous innate immune response. Extracellular vesicles (EV) are believed to play a major role in this parasite-host interplay. Novel cutting-edge technologies are required to gain fundamental insights in the role of parasitic EV proteins because current gene editing and silencing methodologies happen to be inappropriate. Using Nanobodies, this project will develop a strategy to selectively deplete proteins from the EV cargo to allow detailed scrutiny of the molecular players involved in the parasite-immune cell interaction. The impact of EV proteins on kinase activity fingerprints of innate immune cells and their role in a vector-based parasite transmission cycle will be assessed. Collectively, this project will significantly progress our understanding of fundamental aspects of the trypanosome-host interaction.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Sterckx Yann
• Fellow: Claes Mathieu

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Visceral Leishmaniasis (VL) or Kala-Azar is a neglected tropical disease caused by Leishmania parasites that are transmitted by sand flies. Paromomycin (PMM) is used to treat VL patients but was experimentally shown to rapidly induce resistance when applied as a single therapy. We have recently observed that parasites overcome elimination by PMM by hiding in the bone marrow (BM) from where the host can be recolonized. Using combined bioluminescent/fluorescent L. infantum reporter lines with differential susceptibility to PMM, this project will make an in depth analysis of the different cell types in the BM that are infected with L. infantum. Parasite survival in various BM cell types will be evaluated to identify potential sanctuary cells. Parasite isolates from the BM of mice and human patients will be used to explore the acquisition of PMM-resistance in relation to parasite virulence. Infectivity for macrophages and transmissibility by sand flies will serve as indicators for the likelihood of posttreatment parasites to spread. Parallels with treatment of myeloid leukemia, indicate that modulating a specific pathway in hematopoiesis that regulates the BM cellular composition could enhance the efficiency of chemotherapy for VL. Collectively, the proposed multidisciplinary approach will improve our understanding of the complex interactions between the parasite, its host and the drug and will allow the formulation of recommendations for improved treatment interventions.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis
• Fellow: Dirkx Laura

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Visceral Leishmaniasis (VL) or Kala-Azar is a neglected tropical disease caused by Leishmania parasites that are able to survive inside macrophages. Miltefosine is an oral drug used to treat VL patients but is increasingly failing to permanently clear parasites from the patient. Parasites from these relapse patients do not seem to display an increased resistance to the drug but are able to modify the immune system to promote survival inside macrophages even in conditions where the drug is administered. The impact of drug treatment on parasite survival will be evaluated in various tissues using molecular and imaging technologies in rodent models of VL following a natural parasite transmission. Combination of this information with the quantification of drug levels in these tissues, will allow to pinpoint in which tissues parasites are most likely to survive drug treatment. The expression of genes following infection and drug treatment will be analyzed inside infected liver macrophages (Kupffer cells, KCs) in order to understand how parasites from relapsed patients can survive inside host cells. Using transgenic mouse models, this research will allow to evaluate the impact of KCs and KC gene expression on infection and treatment outcome. Collectively, the proposed multidisciplinary approach will improve our understanding of the complex interactions between the parasite, its host and the drug and will allow the formulation of recommendations for improved treatment interventions.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis
• Fellow: Van Bockstal Lieselotte

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Leishmaniasis is a major neglected parasitic disease with a broad range of clinical manifestations including the lethal visceral disease. New drug discovery initiatives are essential given the serious adverse effects of current treatments and/or the increasing threat of drug resistance development. The present project aims to contribute towards novel concepts on intervention strategies that could bypass some problems relating to drug failure. Through the establishment of a sand fly colony, host-parasite interactions such as parasite virulence, disease-associated immunity and pathology, and treatment efficacy will be studied in laboratory rodent models that include the insect vector. The vector component will also allow improved antileishmanial lead characterization, drug resistance research and adaptation of clinical isolates to in vitro and in vivo laboratory models enabling improved monitoring of treatment efficacy in the field. This study will explore the interplay of host immune cells (neutrophils and monocytes) with recent clinical isolates and laboratory strains showing significant differences in virulence that arise from the acquisition of drug resistance. Responses will be studied by using a state-of-the art kinomics platform, that allows a straightforward acquisition of phenotypic fingerprints of intracellular kinase activation. This will provide cutting-edge information on the parasite-host interplay and on inflammation in general. Knowing that neutrophils have been ascribed infection-promoting activities, selective targeting of innate immune cell function will be explored as a complementary asset to control parasitic infections. This has not yet been explored, although anticipated to be much less prone to the development of resistance mechanisms. This approach could possibly also support the identification of novel drug or vaccine targets.

Researcher(s)

• Promoter: Cos Paul
• Co-promoter: Caljon Guy
• Co-promoter: Maes Louis

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Human African trypanosomiasis (HAT) or sleeping sickness is a parasitic disease transmitted by tsetse flies with a relatively benign haemolymphatic followed by a lethal encephalitic stage. Treatment is increasingly compromised by emergence of drug resistance in addition to the known toxicity of current drugs. In response to this medical need, our previous hit-finding campaign identified nucleoside analogues that are highly potent and selective against trypanosomes in vitro and fully curative in vivo after oral administration (50 mg/kg for 5 days) in an acute mouse model. This project will make a structure-activity relationship by expanding two novel compound series to further optimize potency and to make drug uptake less dependent on a single transporter that is prone to resistance development. The chemical synthesis will be combined with detailed evaluation of compound efficacy using state-of-the art methodologies, including natural transmission models and in vivo bioluminescent imaging to assess overall impact of treatment. Aiming to comply with the desired target product profile for such drugs, potency will be evaluated in acute and chronic infections with cerebral involvement. Most promising compounds will be subjected to identification of the action mechanism using loss-of-function and protein biochemical approaches. Collectively, this project aims at providing a convincing proof-of-concept for the use of nucleoside analogues for the treatment of this neglected disease.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Neutrophils and macrophages are cells of the innate immune system of the mammalian host with a range of potential effector functions against pathogens. These cells are rapidly recruited to sites of parasite infection. Counterintuitively, neutrophils favor the onset of parasite infections as we have described for sleeping sickness parasites (Trypanosoma brucei sp.) inoculated by the bites of tsetse flies. Indeed, selective neutrophil removal or genetic conditions resulting in lower neutrophil levels in the blood yield a higher level of resistance to trypanosome infection. Monocytes on the other hand are activated to differentiate into activated macrophages that contribute to parasite control in the early stage of infection. The differential impact of neutrophils and macrophages suggests that specific inhibition of neutrophil functions could result in higher levels of resistance to infection. This project will compare the responses of neutrophils and monocytes to parasite presence by capturing their kinase activity fingerprints. Kinase targets in cell type specific and common responsive pathways will be identified. Kinase inhibitors from commercially available or proprietary collections will be used to selectively inhibit the parasite-induced responses and to evaluate the impact on parasite infection. Collectively, this project will forward our understanding of early trypanosome transmission and is directed at revealing novel transmission-blocking concepts and strategies.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

DNDi has screened a number of non-proprietary compounds that could potentially be used for the treatment of visceral leishmaniasis (VL). DNDi and research partners have further optimised these quality compounds to discover lead compounds or preclinical development candidates. DNDi and the research partners are interested in exploring the mechanisms of action (MOA) of these compounds with regard to Leishmania parasites and resistance (MOR) of the parasites to these compounds. The research will be conducted by the network of research collaborator(s) and may include in vitro and in vivo resistance selection, whole genome sequencing, metabolomics, genetic modification including up-and-down regulation, RIT-seq, PLATO, DiCRE, CISPR/Cas 9 and other applicable methods.

Researcher(s)

• Promoter: Maes Louis
• Co-promoter: Caljon Guy

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Neutrophils and macrophages are cells of the innate immune system of the mammalian host with a range of potential effector functions against pathogens. These cells are rapidly recruited to sites of parasite infection. Counterintuitively, neutrophils favor the onset of parasite infections as we have described for sleeping sickness parasites (Trypanosoma brucei sp.) inoculated by the bites of tsetse flies. Indeed, selective neutrophil removal or genetic conditions resulting in lower neutrophil levels in the blood yield a higher level of resistance to trypanosome infection. Monocytes on the other hand are activated to differentiate into M1 macrophages that contribute to parasite control in the early stage of infection. The differential impact of neutrophils and macrophages suggests that specific inhibition of neutrophil functions could result in higher levels of resistance to infection. This project will compare the responses of neutrophils and monocytes to parasite presence by capturing their kinase activity fingerprints. Kinase targets in cell type specific and common responsive pathways will be identified. Kinase inhibitors from commercially available or proprietary collections will be used to selectively inhibit the parasite-induced responses and to evaluate the impact on parasite infection. Collectively, this project will forward our understanding of early trypanosome transmission and is directed at revealing novel transmission-blocking concepts and strategies.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis
• Fellow: Mabille Dorien

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Treatment of tuberculosis is severely complicated by the adaptations of its etiological agent, Mycobacterium tuberculosis, allowing survival and replication within the host phagocytes. A better understanding of the host-pathogen interaction and the development of novel treatment strategies are thus critical. We strongly believe in a promising strategy involving the receptor-mediated delivery of therapeutics via the endocytic Sialoadhesin (Sn) receptor present on the surface of phagocytes.

Researcher(s)

• Promoter: Cos Paul
• Co-promoter: Caljon Guy
• Co-promoter: Delputte Peter
• Fellow: Cappoen Davie

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

This project specifically envisages undertaking protocol optimizations towards implementation of an RNA-based Leishmania detection method in the post-treatment follow-up of visceral Leishmaniasis patients in upcoming clinical studies in Kenya. The optimization will take into account typical issues encountered in a (tropical) field settings.

Researcher(s)

• Promoter: Caljon Guy

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

This project represents a formal research agreement between UA and on the other hand DNDI. UA provides DNDI research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Neutrophils and macrophages are cells of the innate immune system of the mammalian host with a range of potential effector functions against pathogens. These cells are rapidly recruited to sites of parasite infection. Counterintuitively, neutrophils favor the onset of parasite infections as we have described for sleeping sickness parasites (Trypanosoma brucei sp.) inoculated by the bites of tsetse flies. Indeed, selective neutrophil removal or genetic conditions resulting in lower neutrophil levels in the blood yield a higher level of resistance to trypanosome infection. Monocytes on the other hand are activated to differentiate into M1 macrophages that contribute to parasite control in the early stage of infection. The differential impact of neutrophils and macrophages suggests that specific inhibition of neutrophil functions could result in higher levels of resistance to infection. This project will compare the responses of neutrophils and monocytes to parasite presence by capturing their kinase activity fingerprints. Kinase targets in cell type specific and common responsive pathways will be identified. Kinase inhibitors from commercially available or proprietary collections will be used to selectively inhibit the parasite-induced responses and to evaluate the impact on parasite infection. Collectively, this project will forward our understanding of early trypanosome transmission and is directed at revealing novel transmission-blocking concepts and strategies.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis
• Fellow: Mabille Dorien

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Visceral Leishmaniasis (VL) or Kala-Azar is a neglected tropical disease caused by Leishmania parasites that are able to survive inside macrophages. Miltefosine (MIL) is an oral drug used to treat VL patients but is increasingly failing to permanently clear parasites from the patient. Parasites from these relapse patients do not seem to display an increased resistance to the drug but are able to modify the immune system to promote survival inside macrophages even in conditions where the drug is administered. The impact of drug treatment on parasite survival will be evaluated in various tissues using molecular and imaging technologies in rodent models of VL following a natural parasite transmission. Recently, two syngeneic strains of L. infantum were selected with different levels of sensitivity to MIL-treatment in vivo. The resistant strain (and its sensitive counterpart) was made bioluminescent by introduction of the luciferase enzyme (PpyRE9). The use of bioluminescence imaging (BLI) allows the non-invasive evaluation of the parasite burden and distribution in various tissues and allows assessing the impact of MIL-treatment in vivo. The transgenic parasites will additionally be provided with a fluorescent marker (DsRed or TagGFP2) for detecting parasites by flow cytometry. This project aims to gain insights into the multifactorial causes of MIL-therapy failure and will focus specifically on the impact of the activation state of Kupffer cells (KC) and the recruitment of neutrophils. Infection with the two transgenic parasite lines will be followed by in vivo imaging in (i) KC-reporter (Clec4f-YFP DTR) mice in which KCs can be detected and enriched through their YFP signal and (ii) Genista mice in which a recessive mutation is responsible for a neutropenic condition with absence of mature neutrophils. This approach will allow to gain insights into the cell-based immunological basis of treatment failure. By transcriptional studies, this study will also allow us to identify the involved immunological pathways and potentially allow the design of host-directed therapies to reduce the risk of relapse. The multidisciplinary approach will lead to new insights into the complex interactions between the parasite, the host and the drug and will allow the formulation of recommendations for treatment against VL.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis
• Fellow: Bulté Dimitri

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Amphotericin B (AmB) is currently implemented as first-line treatment for visceral leishmaniasis (VL) in large parts of the world, while the use of miltefosine (MIL) is endorsed as second option, either in mono- or in combination therapy. However, a cumulative number of treatment failures is being reported, requiring the need for repeated treatments that will facilitate emergence of resistance. As isolates from clinical relapse patients generally still demonstrate a 'drug susceptible' phenotype, factors other than intrinsic drug resistance may likely influence treatment outcome. For MIL, increased infectivity and metacyclogenesis potential of the infecting parasites has been suggested, while preliminary observations from our laboratory indicate similarities for AmB. Treatment failure has also been linked to a decreased drug exposure in particular parasite niches, such as in liver granulomas precluding sterile cure upon drug exposure. In this project, the complex interplay between the parasite's (epi-)phenotype, the drug and the host's immune system will be explored using syngeneic VL strains derived from a cure, relapse and resistant background. More in particular, virulence will be compared in the sand fly vector and in in vitro and in vivo laboratory models. The impact of the development of granulomas upon infection with the different strains will be compared in relation to the in vitro and in vivo drug efficacy and relapse potential.

Researcher(s)

• Promoter: Maes Louis
• Co-promoter: Caljon Guy
• Fellow: Hendrickx Sarah

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Visceral Leishmaniasis (VL) or Kala-Azar is a neglected tropical disease caused by Leishmania parasites that are able to survive inside macrophages. Miltefosine is an oral drug used to treat VL patients but is increasingly failing to permanently clear parasites from the patient. Parasites from these relapse patients do not seem to display an increased resistance to the drug but are able to modify the immune system to promote survival inside macrophages even in conditions where the drug is administered. The impact of drug treatment on parasite survival will be evaluated in various tissues using molecular and imaging technologies in rodent models of VL following a natural parasite transmission. Combination of this information with the quantification of drug levels in these tissues, will allow to pinpoint in which tissues parasites are most likely to survive drug treatment. The expression of genes following infection and drug treatment will be analyzed inside infected liver macrophages (Kupffer cells, KCs) in order to understand how parasites from relapsed patients can survive inside host cells. Using transgenic mouse models, this research will allow to evaluate the impact of KCs and KC gene expression on infection and treatment outcome. Collectively, the proposed multidisciplinary approach will improve our understanding of the complex interactions between the parasite, its host and the drug and will allow the formulation of recommendations for improved treatment interventions.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis
• Fellow: Van Bockstal Lieselotte

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Our research focuses on resistance against the only oral drug miltefosine and will provide novel data to the field. Our results will not only be important to the parasitology field, but also to clinicians and public health professionals, supporting clinical decisions on future treatment policies, adequate diagnostic approaches and epidemiological resistance monitoring.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Maes Louis
• Fellow: Eberhardt Eline

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

The BOFZAP research is aimed at understanding the cellular and molecular immunological basis of host tissue colonization by parasite and treatment failure in experimental models of leishmaniasis and trypanosomiasis.

Researcher(s)

• Promoter: Caljon Guy
• Fellow: Caljon Guy

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

This DnDi funded project relates to the preclinical evaluation of lead compounds with anti-parasitic activity for treatment of Leishmaniasis, Chagas disease and African trypanosomiasis. Compounds are also evaluated for cytotoxicity.

Researcher(s)

• Promoter: Caljon Guy
• Co-promoter: Cos Paul
• Co-promoter: Maes Louis

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project

Abstract

Our research focuses on resistance against the only oral drug miltefosine and will provide novel data to the field. Our results will not only be important to the parasitology field, but also to clinicians and public health professionals, supporting clinical decisions on future treatment policies, adequate diagnostic approaches and epidemiological resistance monitoring.

Researcher(s)

• Promoter: Caljon Guy
• Promoter: Maes Louis
• Co-promoter: Cos Paul
• Co-promoter: Maes Louis
• Fellow: Eberhardt Eline

Research team(s)

• Laboratory for Microbiology, Parasitology and Hygiene (LMPH)

Project type(s)

• Research Project