Andy Wullaert associate professor

Research Andy Wullaert

Research team

Expertise

My research group investigates the function of cytosolic protein complexes termed inflammasomes that play important roles in immune responses. Inflammasome activation happens through a sensor protein that senses the trigger, after which a protease termed caspase-1 executes inflammasome functions. Both pathogens and host-derived danger and stress signals can trigger caspase-1 activity of inflammasomes, which then cleaves its substrates. These substrates include Gasdermin D, of which the N-terminal fragment then triggers a lytic form of cell death termed pyroptosis. This inflammasome-induced cell death mode is accompanied by the release of the IL-1β and IL-18 pro-inflammatory cytokines, both of which are maturated by caspase-1 activity, as well as several danger-associated molecular patterns that together mount an efficient inflammatory response. Among the widespread impact of inflammasome signaling on human health, our research focuses on the role of inflammasome signaling and pyroptosis in infectious diseases and auto-inflammatory diseases (AIDs). During infections, inflammasome responses mainly contribute to host defense. Conversely, individuals with gain-of-function mutations in genes encoding inflammasome components suffer from AIDs. For the latter we have several genetic mouse models at our disposal in which inflammasomes are hyperactivated. In the context of infectious diseases, we are investigating murine inflammasome and pyroptosis responses to several viral, bacterial and fungal pathogens. By studying these auto-inflammation and infection mouse models we aim to elucidate the cellular and molecular mechanisms how inflammasome-induced pyroptosis drives auto-inflammatory diseases as well as host defense against pathogens.

Bench-to-bedside research into the role of regulated cell death and barrier dysfunction in inflammation (Infla-Med). 01/01/2026 - 31/12/2031

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.

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  • Research Project

Innate Immune Responses and Cell Death Pathways Triggered by Recent RSV Isolates in hAEC: Unraveling the Influence of Inter-Virus Variability for Insights into Differential Disease Severity. 01/11/2024 - 31/10/2025

Abstract

Respiratory Syncytial Virus (RSV) is a significant cause of respiratory tract infections, particularly affecting young children and the elderly. Why RSV results in asymptomatic or mild infections in some, and life-threatening bronchiolitis in others, remains poorly understood. Severe disease is thought to result from both direct viral damage and excessive immune activation and inflammation. RSV is able to modulate the immediate responses in infected cells, by evading innate antiviral immunity and interfering with cell death pathways that are activated to counteract infection. Currently, the knowledge on how RSV interferes with these protective responses upon infection, and how this might contribute to exaggerated disease is scattered. Most studies use lab strains, potentially lacking key evasion mechanisms and not representing currently circulating strains. It's not yet known if and how virus variability might lead to different immediate cellular responses upon infection, and if this could, at least partially, explain differences in RSV disease severity. This project aims to comprehensively investigate early responses to RSV infection, focusing on innate immunity and cell death pathways, by using a unique library of bona-fide clinical isolates and relevant hAEC cultures. Validation of the results will be done using RSV reverse genetics, and the translational value will be confirmed in a set of >100 nasal samples from RSV-infected infants with different disease severity.

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  • Research Project

INNATE-GAP: a next-generation humanized mouse model for closing the translational gap in innate immunity research. 01/10/2024 - 30/09/2028

Abstract

The species gap is the most challenging obstacle for translating preclinical mouse research towards human medicine. Exactly due to this species gap, human innate immune cells do not develop in immunodeficient NSG mice. This inability to study human innate immune responses in an in vivo context confronts biopharmaceutical companies with difficulties when validating preventive or therapeutic approaches for inflammatory diseases. The INNATE-GAP consortium showed that next-generation NSG-QUAD mice reconstituted with Human Stem and Progenitor Cells (HSPCs) or with human Peripheral Blood Mononuclear Cells (PBMCs) develop human myeloid cells and produce human innate immunity cytokines upon inflammatory challenges. Therefore, the INNATE-GAP project aims to characterize this humanized NSG-QUAD mouse model and to validate its technology readiness for accelerating translation of preclinical innate immunity research as well as for moving towards personalized medicine. First, the cellular composition and functional capacity of reconstituted human innate immune systems in NSGQUAD mice will be studied in depth to determine their applicability window for studying inflammatory diseases, and their potential as a personalized drug testing model. Second, mRNA vaccination and immune-mediated liver disease will serve as case studies for which we will compare inflammatory signatures between humans and humanized NSG-QUAD mice. This will define the human-predictive power of humanized NSG-QUAD mice and may reveal candidate biomarkers and/or druggable targets in these areas. INNATE-GAP will thus deliver a better translatable humanized mouse model that is broadly valuable for companies with interests in inflammatory diseases, as well as early stage biomarker and/or drug target candidates for companies active in mRNA vaccination or hepatology domains. Therefore, our valorization strategy is aimed at follow-up R&D collaborations and/or licensing agreements with our Advisory Board members.

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  • Research Project

Characterizing how excessive linear ubiquitination in myeloid cells modulates inflammasome responses as well as host defence against inflammasome-activating pathogens. 01/01/2024 - 31/12/2027

Abstract

Linear ubiquitin chains are tags that can be attached but also again removed from a protein. The latter is performed by a protein termed OTULIN. Cells lacking OTULIN therefore accumulate linear ubiquitinated proteins and this provokes inflammation in mice and in humans. We identified inhibition of inflammasomes – protein complexes that control secretion of inflammatory cytokines – as a novel mechanism by which OTULIN could control inflammation. This project aims to understand how OTULIN prevents inflammasome responses on the molecular level as well as to investigate its impact on host defence against infections. First, since we found that Nlrp3 inflammasome activation in OTULIN-deficient macrophages was caused by increased necroptotic cell death, we will investigate which linear ubiquitinated proteins modulate necroptosis in these cells. Second, as also Pyrin inflammasome activation is enhanced in OTULIN-deficient macrophages, we will aim to identify the cell death mode and the OTULIN target proteins responsible for Pyrin activation in these cells. And third, extending our ex vivo macrophage findings, we will investigate how the inflammasome promoting effects of myeloid OTULIN deficiency affect the in vivo host response of mice against Nlrp3- or Pyrin-activating pathogens. Overall, this fundamental research project will investigate how the molecular interplay between OTULIN and inflammasome signalling in myeloid cells impacts on inflammatory and infectious responses.

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  • Research Project

Investigating the cell type specific mechanisms by which Gasdermin D-mediated cell death provokes Nlrp3 inflammasome driven inflammation. 01/11/2023 - 31/10/2025

Abstract

Gain-of-function mutations in the Nlrp3 inflammasome cause auto-inflammatory diseases termed cryopyrin-associated periodic syndromes (CAPS). Expressing a CAPS-associated Nlrp3 mutant selectively in either macrophages or neutrophils results in severe inflammation in mice. While it is known that Nlrp3 activation results in lytic cell death due to facilitating Gasdermin D (GSDMD) to form pores in the cell membrane, we will investigate the cell type specific mechanisms by which GSDMD-mediated cell death in either macrophages of neutrophils contributes to Nlrp3-induced CAPS in mice. Using CAPS mice expressing Nlrp3 selectively in either macrophages or neutrophils, we will investigate how different cell death modes control Nlrp3-induced release of pro-inflammatory factors in these mice. In addition, we will analyze serum inflammatory profiles resulting from GSDMD-dependent cell death in either macrophages or neutrophils, and we will aim to identify novel inflammatory mediators produced upon Nlrp3 mutant expression in these cell types. Finally, using a genetic proof-of-principle approach in CAPS mice, we will evaluate the efficacy and safety of GSDMD targeting as a potential future treatment for CAPS patients. A better understanding of the cell type specific mechanisms by which GSDMD-mediated cell death drives Nlrp3-induced CAPS will increase our understanding of how Nlrp3-induced cell death regulates several other inflammatory diseases.

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  • Research Project

Investigating the impact of inflammasome-induced pyroptosis on visceral leishmaniasis in mice. 01/10/2022 - 30/09/2026

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.

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  • Research Project

Dissecting cellular interactions underlying auto-inflammation in Familial Mediterranean Fever. 01/01/2022 - 31/12/2025

Abstract

Familial Mediterranean Fever (FMF) is an auto-inflammatory disease caused by mutations in the gene encoding Pyrin. FMF-associated Pyrin mutants trigger inappropriate inflammasome activation allowing excessive levels of Interleukin (IL)-1β to provoke fever episodes, joint pain, abdominal pain and skin inflammation in FMF patients. We aim to uncover the cellular interactions by which inflammasome- and IL- 1β-induced signaling pathways orchestrate auto-inflammation in FMF. We will employ a genetic approach allowing to abolish either IL-1β production or IL-1β responses in a cell type specific manner in an FMF mouse model, which will experimentally identify these cellular drivers of FMF-related auto-inflammation in mice. In parallel, we will profile single cell transcriptomes as well as cell surface proteins in these FMF mice. This will specifically reveal the gene expression programs of cells displaying the IL-1β receptor on their surface. Guided by this knowledge, inflammasome activation and IL- 1β stimulation experiments will identify IL-1β producing and IL-1β responding cells, respectively, among different types of immune cells obtained from FMF patients. Understanding the cellular level of how inflammasomes and IL-1β cooperate to propel auto-inflammation may facilitate improved therapeutic approaches targeting the driver cell types in FMF, and may uncover common themes that will help to better understand other inflammatory diseases driven by inflammasome and IL-1β signalling.

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  • Research Project

Highly versatile real-time live cell imaging for infectious disease and inflammation research. 01/06/2022 - 31/05/2024

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.

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  • Research Project