Biology subjects

Boivin, G.

Publications and source records attributed to Boivin, G..

12 recordsLinked to original sources

bioRxiv2026

Reprogramming of Lipid Metabolism by FLASH Radiotherapy Selectively Protects Radiosensitive Normal Tissues

FLASH radiotherapy, delivered at ultra-high dose rates exceeding 100 Gy/s, spares normal tissues while maintaining tumor control, yet the molecular mechanisms underlying this differential response remain poorly understood. Here we employed spatial and bulk multi-omics to investigate lipid and protein remodeling in tongue tissue and Mouse oral carcinoma 2 (MOC2) tumors at two weeks post-irradiation with FLASH or conventional dose-rate (CONV) proton radiotherapy. Bulk lipidomics revealed that CONV irradiation induced marked triglyceride (TG) depletion in tongue tissue, whereas FLASH attenuated this depletion. Spatial lipidomics using MALDI-MSI demonstrated that this TG loss was spatially restricted to minor salivary glands, identifying these radiosensitive structures as focal points of radiation-induced lipid damage. Additionally, FLASH irradiation uniquely promoted increases in membrane phospholipids and their lysophospholipid intermediates, consistent with active phospholipid turnover rather than passive damage avoidance. Proteomics revealed divergent metabolic programs: CONV activated a destructive cascade characterized by Ces1d depletion, Acox1-mediated peroxisomal {beta}-oxidation, and Acot7-driven fatty acid overflow, collectively defining a lipid droplet collapse; whereas FLASH engaged a protective program featuring Mgll suppression, Apoe-mediated triglyceride redistribution, and Lypla2-mediated lysophospholipid clearance. We propose a lipid metabolic reprogramming hypothesis in which FLASH not only minimizes acute oxidative damage but actively reprograms lipid metabolism to preserve lipid droplet stores and promote membrane remodeling. These findings provide a putative molecular foundation for the FLASH effect and support published data on the protection of normal tissues.

cancer biology↗

bioRxiv2025

Influenza A Virus Interferes With Respiratory Syncytial Virus in Mice and Reconstituted Human Airway Epithelium

Epidemiological studies suggest that respiratory syncytial virus (RSV) and influenza A virus (IAV) might interfere with each other. Viral interference mainly relies on interferon production elicited by a first virus that reduces the replication of a second virus. In this paper, we first investigated the interactions between RSV-A2 and influenza A(H1N1)pdm09 in BALB/c mice infected with each single virus or both viruses simultaneously or sequentially before, at the peak of interferon elicited by each virus or after that peak. IAV reduced by almost 3.0 logs the replication of RSV administered at the peak of interferon induced by influenza, but the opposite was not true. However, IAV-infected mice challenged with RSV or the vehicle lost more weight and had a lower survival rate compared to single infections. Interferon expression, cytokine levels and pulmonary inflammation were almost similar between groups. Disease worsening was attributed to an aggravation of IAV-induced pulmonary congestion following intranasal instillation of fluid (with or without RSV). In human airway epithelia, IAV also interfered with RSV replication. Viral interference was dependent on the timing and sequence of infections, but not on differential interferon susceptibilities. Overall, our results help to understand the mechanisms of interaction between two major respiratory viruses. ImportanceRespiratory syncytial virus and influenza virus may interfere with each other based on epidemiological studies. It is suggested that a first virus may induce the production of interferon and interfere with the replication of a second unrelated virus. Our data showed that influenza A virus interferes with respiratory syncytial virus replication in mouse lungs, but the opposite was not observed. In reconstituted human airway epithelia, viral interference was dependent on the timing and sequence of infections, but not on differential interferon susceptibilities. Understanding the mechanisms of interaction between respiratory viruses may help the development of prophylactic or therapeutic modalities.

microbiology↗

bioRxiv2024

The Immune Landscape of Tumor-Associated Macrophage Reprogramming

Tumor-associated macrophages (TAMs) generally acquire immunosuppressive and tumor-promoting phenotypes, which may contribute to tumor resistance to immunotherapy. We previously showed that suppression of microRNA activity through genetic Dicer1 inactivation rewires TAMs transcriptomes and prompts their immunostimulatory activation. This phenotypic switch enhanced recruitment and activation of CD8+ cytotoxic T cells (CTLs) and improved the efficacy of immunotherapy in mouse cancer models. Here, we performed single-cell RNA sequencing of whole tumors grown in either wild-type mice or mice with macrophage-specific Dicer1 deletion. The analysis of multiple cell populations, including several discrete monocyte and macrophage subsets, indicated broad and convergent immunostimulatory programming of the tumor microenvironment, which was dependent on CTL-derived interferon-gamma (IFN{gamma}), in mice with DICER-deficient macrophages. Intriguingly, dynamic inferences on monocyte/macrophage ontogeny and differentiation by pseudotime analysis revealed trajectories associated with progression into cell cycle, monocyte-to-macrophage differentiation, and transition from an immunostimulatory to an immunosuppressive phenotype in tumors with DICER-proficient macrophages. Dicer1 deficiency interfered with this trajectory and stalled TAMs at an intermediate state between immature monocytes and macrophages with T cell-stimulatory capacity, thereby impeding immunosuppressive TAM development. This translated into enhanced response to antiangiogenic immunotherapy in an immunotherapy-resistant model of non-small cell lung cancer. Cycling/M2-like macrophages were conserved in human melanoma and hepatocellular carcinoma and should represent a more promising therapeutic target than the bulk of TAMs.

cancer biology↗

bioRxiv2024

Viral interference between severe acute respiratory syndrome coronavirus 2 and influenza A viruses

Some respiratory viruses can cause a viral interference through the activation of the interferon (IFN) pathway that reduces the replication of another virus. Epidemiological studies of coinfections between SARS-CoV-2 and other respiratory viruses have been hampered by non-pharmaceutical measures applied to mitigate the spread of SARS-CoV-2 during the COVID-19 pandemic. With the ease of these interventions, SARS-CoV-2 and influenza A viruses can now co-circulate. It is thus of prime importance to characterize their interactions. In this work, we investigated viral interference effects between an Omicron variant and a contemporary influenza A/H3N2 strain, in comparison with an ancestral SARS-CoV-2 strain and the 2009 pandemic influenza A/H1N1 virus. We infected nasal human airway epitheliums with SARS-CoV-2 and influenza, either simultaneously or 24 h apart. Viral load was measured by RT-qPCR and IFN-/{beta}/{lambda}1/{lambda}2 proteins were quantified by immunoassay. Expression of four interferon-stimulated genes (ISGs; OAS1/IFITM3/ISG15/MxA) was also measured by RT-droplet digital PCR. Additionally, susceptibility of each virus to IFN-/{beta}/{lambda}2 recombinant proteins was determined. Our results showed that influenza A, and especially A/H3N2, interfered with both SARS-CoV-2 viruses, but that SARS-CoV-2 only interfered with A/H1N1. Consistently with these results, influenza, and particularly the A/H3N2 strain, caused a higher production of IFN proteins and expression of ISGs than SARS-CoV-2. The IFN production induced by SARS-CoV-2 was marginal and its presence during coinfections with influenza was associated with a reduced IFN response. All viruses were susceptible to exogenous IFNs, with the ancestral SARS-CoV-2 and Omicron being less susceptible to type I and type III IFNs, respectively. Thus, influenza A causes a viral interference towards SARS-CoV-2 most likely through an IFN response. The opposite is not necessarily true, and a concurrent infection with both viruses leads to a lower IFN response. Taken together, these results help us to understand how SARS-CoV-2 interacts with another major respiratory pathogen. Author summaryDuring the COVID-19 pandemic, non-pharmaceutical measures were able to reduce the spread of SARS-CoV-2 and most respiratory viruses. Since the ease of these measures, SARS-CoV-2 variants and other viruses, such as influenza A, have started to co-circulate and can now infect a same host and interact with each other. These interactions can lead to attenuated or aggravated infections and can affect the timing of epidemics. Therefore, it is very important to elucidate how the new SARS-CoV-2 interacts with other viruses to better predict their implications in human health and their epidemic activity. Our work contributes to better understand these interactions using viruses that have likely co-circulated after lifting mitigation interventions, i.e., SARS-CoV-2 Omicron variant and a contemporary influenza A/H3N2 strain. We studied how each virus may affect the other virus growth and how these interactions were associated with the innate immune response of the host. We found that a prior infection with influenza A can decrease the growth of SARS-CoV-2 while the latter reduces the innate immune response. Our results help to understand the interplay between SARS-CoV-2 and influenza A in the host and may improve mathematical models predicting epidemics.

microbiology↗

bioRxiv2022

In Vitro Selection of Remdesivir-Resistant SARS-CoV-2 Demonstrates High Barrier to Resistance.

In vitro selection of remdesivir-resistant SARS-CoV-2 revealed the emergence of a V166L substitution, located outside of the polymerase active site of the nsp12 protein, after 9 passages. V166L remained the only nsp12 substitution after 17 passages at a final concentration of 10 {micro}M RDV, conferring a 2.3-fold increase in EC50. When V166L was introduced into a recombinant SARS-CoV-2 virus, a 1.5-fold increase in EC50 was observed, indicating a high in vitro barrier to RDV resistance.

microbiology↗

bioRxiv2021

A novel effective live-attenuated human metapneumovirus vaccine candidate produced in the serum-free suspension DuckCelt-T17 cell platform

Human metapneumovirus (HMPV) is a major pediatric respiratory pathogen for which there is currently no specific treatment or licensed vaccine. Different strategies have been evaluated to prevent this infection, including the use of live-attenuated vaccines (LAVs). However, further development of LAV approaches is often hampered by the lack of highly efficient and scalable cell-based production systems that support worldwide vaccine production. In this context, avian cell lines cultivated in suspension are currently competing with traditional cell platforms used for viral vaccine manufacturing. We investigated whether the DuckCelt(R)-T17 avian cell line (Vaxxel) we previously described as an efficient production system for several influenza strains could also be used to produce a new HMPV LAV candidate (Metavac(R)), an engineered SH gene-deleted mutant of the A1/C-85473 strain of HMPV. To that end, we characterized the operational parameters of multiplicity of infection (MOI), cell density, and trypsin addition to achieve optimal production of the LAV Metavac(R) in the DuckCelt(R)-T17 cell line platform. We demonstrated that the DuckCelt(R)-T17 cell line is permissive and is well adapted to the production of the wild-type A1/C-85473 HMPV and the Metavac(R) vaccine candidate. Moreover, our results confirmed that the LAV candidate produced in DuckCelt(R)-T17 cells conserves its advantageous replication properties in LLC-MK2 and 3D-reconstituted human airway epithelium models, as well as its capacity to induce efficient neutralizing antibodies in a mouse model. Our results suggest that the DuckCelt(R)-T17 avian cell line is a very promising platform for scalable in-suspension serum-free production of the HMPV-based LAV candidate Metavac(R).

immunology↗

bioRxiv2021

Impact of temperature on the affinity of SARS-CoV-2 Spike for ACE2

The seasonal nature in the outbreaks of respiratory viral infections with increased transmission during low temperatures has been well established. The current COVID-19 pandemic makes no exception, and temperature has been suggested to play a role on the viability and transmissibility of SARS-CoV-2. The receptor binding domain (RBD) of the Spike glycoprotein binds to the angiotensin-converting enzyme 2 (ACE2) to initiate viral fusion. Studying the effect of temperature on the receptor-Spike interaction, we observed a significant and stepwise increase in RBD-ACE2 affinity at low temperatures, resulting in slower dissociation kinetics. This translated into enhanced interaction of the full Spike to ACE2 receptor and higher viral attachment at low temperatures. Interestingly, the RBD N501Y mutation, present in emerging variants of concern (VOCs) that are fueling the pandemic worldwide, bypassed this requirement. This data suggests that the acquisition of N501Y reflects an adaptation to warmer climates, a hypothesis that remains to be tested.

microbiology↗

bioRxiv2020

Human Respiratory Syncytial Virus-induced immune signature of infection revealed by transcriptome analysis of clinical pediatric nasopharyngeal swab samples

Human Respiratory Syncytial Virus (HRSV) constitutes one the main causes of respiratory infection in neonates and infants worldwide. Transcriptome analysis of clinical samples using high-throughput technologies remains an important tool to better understand virus-host complex interactions in the real-life setting but also to identify new diagnosis/prognosis markers or therapeutics targets. A major challenge when exploiting clinical samples such as nasal swabs, washes or bronchoalveolar lavages is the poor quantity and integrity of nucleic acids. In this study, we applied a tailored transcriptomics workflow to exploit nasal wash samples from children who tested positive for HRSV. Our analysis revealed a characteristic immune signature as a direct reflection of HRSV pathogenesis and highlighted putative biomarkers of interest.

microbiology↗

bioRxiv2019

Strain-dependent impact of G and SH deletions provide new insights for live-attenuated HMPV vaccine development

Human metapneumovirus (HMPV) is a major pediatric respiratory pathogen with currently no specific treatment or licensed vaccine. Different strategies to prevent this infection have been evaluated, including live-attenuated vaccines (LAV) based on SH and/or G protein deletions. This approach showed promising outcomes but has not been evaluated further using different viral strains. In that regard, we previously showed that different HMPV strains harbor distinct in vitro fusogenic and in vivo pathogenic phenotypes, possibly influencing the selection of vaccine strains. In this study, we investigated the putative contribution of the low conserved SH or G accessory proteins in such strain-dependent phenotypes and generated recombinant wild type (WT) and SH- or G-deleted viruses derived from two different patient-derived HMPV strains, A1/C-85473 and B2/CAN98-75.\n\nThe {Delta}SH and {Delta}G deletions led to different strain-specific phenotypes in both LLC-MK2 cell and reconstituted human airway epithelium models. More interestingly, the {Delta}G-85473 and especially {Delta}SH-C-85473 recombinant viruses conferred significant protection against HMPV challenge and induced immunogenicity against a heterologous strain. In conclusion, our results show that the viral genetic backbone should be considered in the design of live-attenuated HMPV vaccines, and that a SH-deleted virus based on the A1/C-85473 HMPV strain could be a promising LAV candidate as it is both attenuated and protective in mice while being efficiently produced in a cell-based system.

microbiology↗

bioRxiv2019

Molecular pathway of influenza pan-neuraminidase inhibitors resistance in an immunocompromised patient

Neuraminidase (NA) inhibitors (NAIs), including oseltamivir and zanamivir, play an important therapeutic role against influenza infections in immunocompromised patients. In such settings, however, NAI therapy may lead to the emergence of resistance involving mutations within the influenza surface genes. The aim of this study was to investigate the evolution of hemagglutinin (HA) and NA genes of influenza A(H1N1)pdm09 virus in an immunocompromised patient receiving oseltamivir then zanamivir therapies. Nasopharyngeal swabs (NPS) samples were collected between 01-27-2018 and 04-20-2018 from a hematopoietic stem cell transplant recipient. These included 11 samples collected either pre-therapy, during oseltamivir and zanamivir as well as after therapy. The A(H1N1)pdm09 HA/NA genes were sequenced. The H275Y NA substitution was quantified by droplet digital RT-PCR assay. A(H1N1)pdm09 recombinant viruses containing HA mutations were tested by HA elution experiments to investigate in vitro binding properties. Oseltamivir rapidly induced the H275Y NA mutation which constituted 98.33% of the viral population after 15 days of oseltamivir treatment. The related HA gene contained S135A and P183S substitutions within the receptor-binding site. After a switch to zanamivir, 275H/Y and 119E/G/D mixed populations were detected. In the last samples, the double H275Y-E119G NA variant dominated with S135A and P183S HA substitutions. This report confirms that oseltamivir can rapidly induce the emergence of the H275Y substitution in A(H1N1)pdm09 viruses and subsequent switch to zanamivir can lead to additional substitutions at codon E119 resulting in multi-drug resistance. Such data highlight the need for novel antiviral agents.

microbiology↗

bioRxiv2018

Efficient and specific Ly6G+ cell depletion: A change in the current practices toward more relevant functional analyses of neutrophils

Neutrophils orchestrate the innate immune response against microorganisms and are increasingly recognized to modulate cancer development in primary tumors and metastases. To address their function in vivo, different approaches are used, the most common ones relying on antibody-mediated neutrophil depletion. By comparing the effects of two widely used antibodies, we demonstrate a strong efficacy but a lack of specificity for anti-Gr1. In contrast, anti-Ly6G lacks neutrophil-depletion capacity in C57BL/6 mice, which can be explained by an insufficient celerity of neutrophil clearance that is counterbalanced by exacerbated mobilization of immature cells. When combined with a secondary antibody, anti-Ly6G treatment results in specific and efficient neutrophil depletion. Using a mouse model of lung adenocarcinoma, we demonstrate the efficacy of this new approach to diminish primary tumor growth and propose the existence of a local intercellular communication between neutrophils and alveolar macrophages that fosters regulatory T cell proliferation in lung cancer.

immunology↗

bioRxiv2018

Repurposing of drugs as novel influenza inhibitors from clinical gene expression infection signatures

BackgroundInfluenza virus infections remain a major and recurrent public health burden. The intrinsic ever-evolving nature of this virus, the suboptimal efficacy of current influenza inactivated vaccines, as well as the emergence of resistance against a limited antiviral arsenal, highlight the critical need for novel therapeutic approaches. In this context, the aim of this study was to develop and validate an innovative strategy for drug repurposing as host-targeted inhibitors of influenza viruses and the rapid evaluation of the most promising candidates in Phase II clinical trials.\n\nMethodsWe exploited in vivo global transcriptomic signatures of infection directly obtained from a patient cohort to determine a shortlist of already marketed drugs with newly identified, host-targeted inhibitory properties against influenza virus. The antiviral potential of selected repurposing candidates was further evaluated in vitro, in vivo and ex vivo.\n\nResultsOur strategy allowed the selection of a shortlist of 35 high potential candidates out of a rationalized computational screening of 1,309 FDA-approved bioactive molecules, 31 of which were validated for their significant in vitro antiviral activity. Our in vivo and ex vivo results highlight diltiazem, a calcium channel blocker currently used in the treatment of hypertension, as a promising option for the treatment of influenza infections. Additionally, transcriptomic signature analysis further revealed the so far undescribed capacity of diltiazem to modulate the expression of specific genes related to the host antiviral response and cholesterol metabolism. Finally, combination treatment with diltiazem and virus-targeted oseltamivir neuraminidase inhibitor further increased antiviral efficacy, prompting rapid authorization for the initiation of a Phase II clinical trial.\n\nConclusionsThis original, host-targeted, drug repurposing strategy constitutes an effective and highly reactive process for the rapid identification of novel anti-infectious drugs, with potential major implications for the management of antimicrobial resistance and the rapid response to future epidemic or pandemic (re)emerging diseases for which we are still disarmed.

microbiology↗