Isabelle Mija Laetitia Guerin ep. Bonne
Email Address
i.bonne@nus.edu.sg
Organizational Units
YONG LOO LIN SCH OF MEDICINE
faculty
SPECIALTY RESEARCH INST/CTRS
faculty
8 results
Publication Search Results
Now showing 1 - 8 of 8
Publication Chikungunya virus replication in salivary glands of the mosquito aedes albopictus(MDPI AG, 2015) Vega-Rúa, A; Schmitt, C; Bonne, I; Locker, J.K; Failloux, A.-B; LIFE SCIENCES INSTITUTEChikungunya virus (CHIKV) is an emerging arbovirus transmitted to humans by mosquitoes such as Aedes albopictus. To be transmitted, CHIKV must replicate in the mosquito midgut, then disseminate in the hemocele and infect the salivary glands before being released in saliva. We have developed a standardized protocol to visualize viral particles in the mosquito salivary glands using transmission electron microscopy. Here we provide direct evidence for CHIKV replication and storage in Ae. albopictus salivary glands. © 2015 by the authors.Publication cccDNA-Targeted Drug Screen Reveals a Class of Antihistamines as Suppressors of HBV Genome Levels(MDPI, 2023-09-24) Ren, Ee Chee; Zhuo, Nicole Ziyi; Goh, Zhi Yi; Bonne, Isabelle; Malleret, Benoit; Ko, Hui Ling; Dr Isabelle Mija Laetitia Guerin ep. Bonne; MICROBIOLOGY AND IMMUNOLOGY; LIFE SCIENCES INSTITUTE; PSYCHOLOGICAL MEDICINEChronic infection with hepatitis B virus (HBV) is incurable, as the current therapeutics cannot eliminate its persistent genomic material, cccDNA. Screening systems for cccDNA-targeting therapeutics are unavailable, as low copies of cccDNA in vitro complicate detection. To address this, cccDNA copies were massively increased to levels detectable via automated plate readers. This was achieved via continuous infection in a contact-free co-culture of an HBV generator (clone F881), which stably produced clinically relevant amounts of HBV, and HBV acceptors selected to carry high cccDNA loads. cccDNA-targeted therapeutics were then identified via reduced cccDNA-specific fluorescence, taking differences in the cell numbers and viability into account. Amongst the drugs tested, the H1 antihistamine Bilastine, HBVCP inhibitors and, surprisingly, current HBV therapeutics downregulated the cccDNA significantly, reflecting the assay’s accuracy and sensitivity in identifying drugs that induce subtle changes in cccDNA levels, which take years to manifest in vivo. Bilastine was the only therapeutic that did not reduce HBV production from F881, indicating it to be a novel direct suppressor of cccDNA levels. When further assessed, only the structurally similar antihistamines Pitolisant and Nizatidine suppressed cccDNA levels when other H1 antihistamines could not. Taken together, our rapid fluorescence cccDNA-targeted drug screen successfully identified a class of molecules with the potential to treat hepatitis B.Publication Studies on B Cells in the Fruit-Eating Black Flying Fox (Pteropus alecto)(FRONTIERS MEDIA SA, 2019-03-14) Periasamy, Pravin; Hutchinson, Paul E; Chen, Jinmiao; Bonne, Isabelle; Hameed, Shahana Shereene Shahul; Selvam, Pavithra; Hey, Ying Ying; Fink, Katja; Irving, Aaron T; Dutertre, Charles-Antoine; Bakers, Michelle; Crameri, Gary; Wang, Lin-Fa; Alonso, Sylvie; Dr Paul Edward Hutchinson; MICROBIOLOGY AND IMMUNOLOGY; LIFE SCIENCES INSTITUTE; DUKE-NUS MEDICAL SCHOOLThe ability of bats to act as reservoir for viruses that are highly pathogenic to humans suggests unique properties and functional characteristics of their immune system. However, the lack of bat specific reagents, in particular antibodies, has limited our knowledge of bat's immunity. Here, we report a panel of cross-reactive antibodies against MHC-II, NK1.1, CD3, CD21, CD27, and immunoglobulin (Ig), that allows flow cytometry analysis of B, T and NK cell populations in two different fruit-eating bat species namely, Pteropus alecto and E. spelaea. Results confirmed predominance of T cells in the spleen and blood of bats, as previously reported by us. However, the percentages of B cells in bone marrow and NK cells in spleen varied greatly between wild caught P. alecto bats and E. spelaea colony bats, which may reflect inherent differences of their immune system or different immune status. Other features of bat B cells were investigated. A significant increase in sIg+ B cell population was observed in the spleen and blood from LPS-injected bats but not from poly I:C-injected bats, supporting T-independent polyclonal B cell activation by LPS. Furthermore, using an in vitro calcium release assay, P. alecto B cells exhibited significant calcium release upon cross-linking of their B cell receptor. Together, this work contributes to improve our knowledge of bat adaptive immunity in particular B cells.Publication iPS-cell-derived microglia promote brain organoid maturation via cholesterol transfer(NATURE PORTFOLIO, 2023-11-09) Park, Dong Shin; Kozaki, Tatsuya; Tiwari, Satish Kumar; Moreira, Marco; Khalilnezhad, Ahad; Torta, Federico; Olivie, Nicolas; Thiam, Chung Hwee; Liani, Oniko; Silvin, Aymeric; Phoo, Wint Wint; Gao, Liang; Triebl, Alexander; Tham, Wai Kin; Goncalves, Leticia; Kong, Wan Ting; Raman, Sethi; Zhang, Xiao Meng; Dunsmore, Garett; Dutertre, Charles Antoine; Lee, Salanne; Ong, Jia Min; Balachander, Akhila; Khalilnezhad, Shabnam; Lum, Josephine; Duan, Kaibo; Lim, Ze Ming; Tan, Leonard; Low, Ivy; Utami, Kagistia Hana; Yeo, Xin Yi; Di Tommaso, Sylvaine; Dupuy, Jean-William; Varga, Balazs; Karadottir, Ragnhildur Thora; Madathummal, Mufeeda Changaramvally; Bonne, Isabelle; Malleret, Benoit; Binte, Zainab Yasin; Da, Ngan Wei; Tan, Yingrou; Wong, Wei Jie; Zhang, Jinqiu; Chen, Jinmiao; Sobota, Radoslaw M; Howland, Shanshan W; Ng, Lai Guan; Saltel, Frederic; Castel, David; Grill, Jacques; Minard, Veronique; Albani, Salvatore; Chan, Jerry KY; Thion, Morgane Sonia; Jung, Sang Yong; Wenk, Markus R; Pouladi, Mahmoud A; Pasqualini, Claudia; Angeli, Veronique; Cexus, Olivier NF; Ginhoux, Florent; Assoc Prof Veronique Angeli; MICROBIOLOGY AND IMMUNOLOGY; LIFE SCIENCES INSTITUTE; DUKE-NUS MEDICAL SCHOOL; BIOCHEMISTRYMicroglia are specialized brain-resident macrophages that arise from primitive macrophages colonizing the embryonic brain1. Microglia contribute to multiple aspects of brain development, but their precise roles in the early human brain remain poorly understood owing to limited access to relevant tissues2–6. The generation of brain organoids from human induced pluripotent stem cells recapitulates some key features of human embryonic brain development7–10. However, current approaches do not incorporate microglia or address their role in organoid maturation11–21. Here we generated microglia-sufficient brain organoids by coculturing brain organoids with primitive-like macrophages generated from the same human induced pluripotent stem cells (iMac)22. In organoid cocultures, iMac differentiated into cells with microglia-like phenotypes and functions (iMicro) and modulated neuronal progenitor cell (NPC) differentiation, limiting NPC proliferation and promoting axonogenesis. Mechanistically, iMicro contained high levels of PLIN2+ lipid droplets that exported cholesterol and its esters, which were taken up by NPCs in the organoids. We also detected PLIN2+ lipid droplet-loaded microglia in mouse and human embryonic brains. Overall, our approach substantially advances current human brain organoid approaches by incorporating microglial cells, as illustrated by the discovery of a key pathway of lipid-mediated crosstalk between microglia and NPCs that leads to improved neurogenesis.Publication Characterisation of a human antibody that potentially links cytomegalovirus infection with systemic lupus erythematosus.(Springer Science and Business Media LLC, 2019-07-10) Neo, Jie Ying Jacklyn; Wee, Seng Yin Kelly; Bonne, Isabelle; Tay, Sen Hee; Raida, Manfred; Jovanovic, Vojislav; Fairhurst, Anna-Marie; Lu, Jinhua; Hanson, Brendon J; MacAry, Paul A; Dr Guerin ep. Bonne, Isabelle Mija Laetitia; MEDICINE; MICROBIOLOGY AND IMMUNOLOGY; LIFE SCIENCES INSTITUTEHuman cytomegalovirus (HCMV) is a ubiquitous herpesvirus that has been linked with the development of systemic lupus erythematosus (SLE). Thus far, molecular mimicry has been implicated as the principal mechanism that explains this association. In this study, we characterise a potential alternative process whereby HCMV contributes to SLE. In a cohort of SLE patients, we show a significant association between HCMV infection and SLE through a human antibody response that targets UL44. UL44 is an obligate nuclear-resident, non-structural viral protein vital for HCMV DNA replication. The intracellular nature of this viral protein complicates its targeting by the humoral response - the mechanism remains unresolved. To characterise this response, we present a thorough molecular analysis of the first human monoclonal antibody specific for UL44 derived from a HCMV seropositive donor. This human antibody immunoprecipitates UL44 from HCMV-infected cells together with known nuclear-resident SLE autoantigens - namely, nucleolin, dsDNA and ku70. We also show that UL44 is redistributed to the cell surface during virus-induced apoptosis as part of a complex with these autoantigens. This phenomenon represents a potential mechanism for the bystander presentation of SLE autoantigens to the humoral arm of our immune system under circumstances that favour a break in peripheral tolerance.Publication Prohibitin plays a critical role in Enterovirus 71 neuropathogenesis(Public Library of Science, 2018) Too I.H.K.; Bonne I.; Tan E.L.; Chu J.J.H.; Alonso S.; MICROBIOLOGY AND IMMUNOLOGY; PAEDIATRICSA close relative of poliovirus, enterovirus 71 (EV71) is regarded as an important neurotropic virus of serious public health concern. EV71 causes Hand, Foot and Mouth Disease and has been associated with neurological complications in young children. Our limited understanding of the mechanisms involved in its neuropathogenesis has hampered the development of effective therapeutic options. Here, using a two-dimensional proteomics approach combined with mass spectrometry, we have identified a unique panel of host proteins that were differentially and dynamically modulated during EV71 infection of motor-neuron NSC-34 cells, which are found at the neuromuscular junctions where EV71 is believed to enter the central nervous system. Meta-analysis with previously published proteomics studies in neuroblastoma or muscle cell lines revealed minimal overlapping which suggests unique host-pathogen interactions in NSC-34 cells. Among the candidate proteins, we focused our attention on prohibitin (PHB), a protein that is involved in multiple cellular functions and the target of anti-cancer drug Rocaglamide (Roc-A). We demonstrated that cell surface-expressed PHB is involved in EV71 entry into neuronal cells specifically, while membrane-bound mitochondrial PHB associates with the virus replication complex and facilitates viral replication. Furthermore, Roc-A treatment of EV71-infected neuronal cells reduced significantly virus yields. However, the inhibitory effect of Roc-A on PHB in NSC-34 cells was not through blocking the CRAF/MEK/ERK pathway as previously reported. Instead, Roc-A treated NSC-34 cells had lower mitochondria-associated PHB and lower ATP levels that correlated with impaired mitochondria integrity. In vivo, EV71-infected mice treated with Roc-A survived longer than the vehicle-treated animals and had significantly lower virus loads in their spinal cord and brain, whereas virus titers in their limb muscles were comparable to controls. Together, this study uncovers PHB as the first host factor that is specifically involved in EV71 neuropathogenesis and a potential drug target to limit neurological complications. © 2018 Too et al.Publication Drosophila cells use nanotube-like structures to transfer dsRNA and RNAi machinery between cells(Nature Publishing Group, 2016) Karlikow, M; Goic, B; Mongelli, V; Salles, A; Schmitt, C; Bonne, I; Zurzolo, C; Saleh, M.-C; LIFE SCIENCES INSTITUTETunnelling nanotubes and cytonemes function as highways for the transport of organelles, cytosolic and membrane-bound molecules, and pathogens between cells. During viral infection in the model organism Drosophila melanogaster, a systemic RNAi antiviral response is established presumably through the transport of a silencing signal from one cell to another via an unknown mechanism. Because of their role in cell-cell communication, we investigated whether nanotube-like structures could be a mediator of the silencing signal. Here, we describe for the first time in the context of a viral infection the presence of nanotube-like structures in different Drosophila cell types. These tubules, made of actin and tubulin, were associated with components of the RNAi machinery, including Argonaute 2, double-stranded RNA, and CG4572. Moreover, they were more abundant during viral, but not bacterial, infection. Super resolution structured illumination microscopy showed that Argonaute 2 and tubulin reside inside the tubules. We propose that nanotube-like structures are one of the mechanisms by which Argonaute 2, as part of the antiviral RNAi machinery, is transported between infected and non-infected cells to trigger systemic antiviral immunity in Drosophila.Publication MFSD7c functions as a transporter of choline at the blood-brain barrier(SPRINGERNATURE, 2024-03) Nguyen, Xuan Thi Anh; Le, Thanh Nha Uyen; Nguyen, Toan Q; Thi Thuy Ha, Hoa; Artati, Anna; Leong, Nancy CP; Nguyen, Dat T; Lim, Pei Yen; Susanto, Adelia Vicanatalita; Huang, Qianhui; Fam, Ling; Leong, Lo Ngah; Bonne, Isabelle; Lee, Angela; Granadillo, Jorge L; Gooch, Catherine; Yu, Dejie; Huang, Hua; Soong, Tuck Wah; Chang, Matthew Wook; Wenk, Markus R; Adamski, Jerzy; Cazenave-Gassiot, Amaury; Nguyen, Long N; Dr Isabelle Mija Laetitia Guerin ep. Bonne; PHYSIOLOGY; INTERACTIVE & DIGITAL MEDIA INSTITUTE; LIFE SCIENCES INSTITUTE; BIOCHEMISTRYMutations in the orphan transporter MFSD7c (also known as Flvcr2), are linked to Fowler syndrome. Here, we used Mfsd7c knockout (Mfsd7c–/–) mice and cell-based assays to reveal that MFSD7c is a choline transporter at the blood–brain barrier (BBB). We performed comprehensive metabolomics analysis and detected differential changes of metabolites in the brains and livers of Mfsd7c–/–embryos. Particularly, we found that choline-related metabolites were altered in the brains but not in the livers of Mfsd7c–/– embryos. Thus, we hypothesized that MFSD7c regulates the level of choline in the brain. Indeed, expression of human MFSD7c in cells significantly increased choline uptake. Interestingly, we showed that choline uptake by MFSD7c is greatly increased by choline-metabolizing enzymes, leading us to demonstrate that MFSD7c is a facilitative transporter of choline. Furthermore, single-cell patch clamp analysis showed that the import of choline by MFSD7c is electrogenic. Choline transport function of MFSD7c was shown to be conserved in vertebrates, but not in yeasts. We demonstrated that human MFSD7c is a functional ortholog of HNM1, the yeast choline importer. We also showed that several missense mutations identified in patients exhibiting Fowler syndrome had abolished or reduced choline transport activity. Mice lacking Mfsd7c in endothelial cells of the central nervous system suppressed the import of exogenous choline from blood but unexpectedly had increased choline levels in the brain. Stable-isotope tracing study revealed that MFSD7c was required for exporting choline derived from lysophosphatidylcholine in the brain. Collectively, our work identifies MFSD7c as a choline exporter at the BBB and provides a foundation for future work to reveal the disease mechanisms of Fowler syndrome.