Biology subjects

Seguin-Devaux, C.

Publications and source records attributed to Seguin-Devaux, C..

6 recordsLinked to original sources

bioRxiv2026

Strength in Unity: a Dual Strategy to Restore NK Cell Cytotoxicity against Pancreatic Ductal Adenocarcinoma

BackgroundPancreatic ductal adenocarcinoma (PDAC), a condition representing 90% of pancreatic cancers, shows one of the lowest 5-year survival rates across all cancer types. Current therapeutic approaches remain largely inefficient, in part due to the presence of a hostile tumor microenvironment (TME), impeding immune cells infiltration and function. Specifically, Natural Killer (NK) cells from PDAC patients exhibit impaired phenotype and cytotoxic functions. NK cell immunotherapy represents a safe and promising approach to restore NK cell cytotoxicity against PDAC. MethodsWe developed a dual strategy based on i) the re-activation of NK cells through Natural Killer activating multimeric immunotherapeutic complexes (NaMiX) composed of IL-15/IL-15R dimers coupled to anti-NKp46 single-chain variable fragments (scFvs) and ii) the crosslinking of activated NK cells to PDAC cells with a Trispecific Killer Engager (TriKE) targeting NKG2D, NKp30 and the tumor-associated antigen CEA. We evaluated the ability of these constructs to stimulate NK cell functions across BxPC-3 PDAC cell line and patient-derived organoid models and in humanized NSG mice bearing PDAC xenografts. ResultsNaMiX stimulated the activation and cytotoxic functions of NK cells towards pancreatic BxPC-3 cells in vitro while TriKE cross-linked NK cells to BxPC-3 cells. The cytotoxic effects of NaMiX were further enhanced when combined with the crosslinking abilities of TriKE for the killing of NK cell-mediated BxPC-3 spheroid and PDAC patient-derived organoids. In humanized mice bearing BxPC-3 xenografts, NaMiX induced cytotoxic lymphocyte expansion, and increased tumor infiltration of NK cells, while TriKE tended to slow tumor progression. ConclusionsThis proof-of-concept study reports for the first time that activating and engaging NK cells with immunoconjugates are a promising therapeutic avenue for PDAC treatment. Efforts should now focus on the optimization of NK cell therapeutic modalities to favor the infiltration of a high number of NK cells into the tumor.

immunology↗

bioRxiv2025

Humanized glioblastoma patient-derived orthotopic xenografts recreate a locally immunosuppressed human immune ecosystem amenable to immunotherapeutic modulation

Immune-based strategies have so far failed to demonstrate clinical benefit in glioblastoma (GBM), largely due to the profound immunosuppressive tumor microenvironment (TME). To achieve more predictive preclinical insights, advanced in vivo models that faithfully recapitulate the human brain immune landscape are urgently needed. Here, we established GBM patient-derived orthotopic xenografts (PDOXs) across diverse mouse strains, including humanized models. Humanization was achieved through transplantation of CD34+ hematopoietic stem cells (HU-CD34+) or peripheral blood mononuclear cells (HU-PBMC). Both models successfully reconstituted human T-cells systemically, with stronger engraftment in HU-CD34+ mice. We observed selective infiltration and spatial organization to intracranial GBM tumors, including exhausted, memory-like, and regulatory CD4+ T-cell phenotypes, TIM-3+ immunosuppressive-like myeloid cells and intratumoral B cells. Mouse microglia-derived tumor-associated macrophages (TAMs) remained the dominant immunosuppressive immune population. Anti-PD-1 therapy, but not anti-GITR, modestly modulated the infiltration dynamics, demonstrating the susceptibility of the reconstructed adaptive immunity to immunotherapeutic intervention. These findings position humanized GBM PDOXs as a relevant preclinical platform to interrogate tumor-immune interactions and evaluate immunotherapeutic strategies in a human context. Key pointsO_LIGBM PDOXs developed in HU-CD34+ and HU-PBMC mice faithfully reconstitute systemic and local human adaptive immunity. C_LIO_LIHuman immune components undergo selective infiltration, spatial organization and transition towards exhausted CD4+ T-cells and immunosuppressive CD11c+ myeloid cells. C_LIO_LIAnti-PD-1, but not anti-GITR, locally promote human immune infiltration into intracranial GBM tumors, while sparing systemic compartments. C_LIO_LIHumanized GBM PDOXs provide a powerful preclinical platform to test novel immunotherapeutic strategies. C_LI Study importanceImmune checkpoint blockade has shown limited efficacy in GBM, reflecting the highly immunosuppressive and lymphocyte-poor nature of the TME. Conventional syngeneic and GEMM models fail to recapitulate these features, contributing to the translational disconnect between preclinical success and clinical failure. Humanized mice provide a solution to interrogate human-specific immunity in vivo, but their use in GBM has remained limited. Here, we provide the first comparison of GBM PDOX modeling in two complementary modes of humanization based on CD34+ HSCs and PBMCs. We systematically profile systemic and intratumoral compartments, showing that these models faithfully reconstitute human adaptive immunity and capture the interplay with the murine brain TME. Furthermore, we demonstrate clinically-relevant responses upon treatment with checkpoint antibodies targeting PD-1 and GITR, showing modulation of human immune subsets without altering murine TAM immunosuppression, underscoring the translational value of the system. This study establishes humanized GBM PDOXs as a versatile platform for dissecting tumor-immune interactions in the brain and for preclinical evaluation and development of novel immunotherapies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/689484v2_ufig1.gif" ALT="Figure 1"> View larger version (74K): org.highwire.dtl.DTLVardef@1b684e1org.highwire.dtl.DTLVardef@1cdfbbdorg.highwire.dtl.DTLVardef@4a570borg.highwire.dtl.DTLVardef@98b112_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2024

Complement-Activating Multimeric Immunotherapeutic Complexes for HER2-breast cancer immunotherapy

BackgroundDirecting selective complement activation towards tumor cells is an attractive strategy to promote their elimination. We have generated Complement-activating Multimeric immunotherapeutic compleXes (CoMiX) that selectively stimulate the alternative pathway using Factor H Related protein 4 (FHR4) or the classical complement pathways using triple Fc dimers on HER2-expressing tumor cells. MethodsWe used the C4bp C-terminal--/{beta}-chain multimerising scaffolds to generate CoMiX-FHR4 and CoMiX-Fc with 2 different VHH anti-HER2, VHH(T) and VHH(P), recognising trastuzumab-or pertuzumab-competing HER2 epitopes, respectively: FHR4/VHH(T), FHR4/VHH(P), VHH(T)/Fc, VHH(P)/Fc. The different CoMiX were compared in vitro for C3b and C5b9 depositions, complement-dependent cytotoxicity, and their ability to activate NK cells and phagocytosis by macrophages using one-way ANOVA and post-hoc Tukeys tests. We further explored their therapeutic efficacy in vivo on human BT474 breast cancer xenografts established in NUDE mice, when used individually or in combination, as compared to trastuzumab or pertuzumab. ResultsFHR4/VHH(T) and FHR4/VHH(P) led to the highest C3b and C5b9 depositions and CDC, both individually and in combinations on BT474 tumor cells (p< 0.0001) surpassing the very low complement activating capacity of trastuzumab and pertuzumab. CoMiX-Fc showed NK cell activation and complement-mediated BT474 phagocytosis by M2 macrophages. In the xenograft model, CoMiX-FHR4 molecules reduced the tumor volume by a factor of 7.33 compared to the PBS control. VHH(T)/Fc had no effect on tumor growth, while VHH(P)/Fc led to a 2.75-times tumor volume reduction that was higher than pertuzumab (p< 0.01). Trastuzumab and its combination with pertuzumab remained the most potent regimen, alone or in combination, to completely inhibit tumor growth. CoMiX-FHR4, CoMiX-Fc and C3b deposition were visualized as soon as one hour after injection resulting in a massive homogeneous complement deposit 6 hours after injection. Interestingly, CoMiX-FHR4 significantly reduced the growth of trastuzumab-resistant cancer cells in contrast to trastuzumab and induced a large NK cell infiltration into the tumor. ConclusionsCoMiX-FHR4 and CoMiX VHH(P)/Fc significantly inhibit tumor growth through complement activation, NK cells infiltration, and phagocytosis by macrophages. CoMiX-FHR4 proteins delay xenograft growth of BT474 cells resistant to trastuzumab and could thus be an attractive approach when resistance to antibody emerges. Key messagesO_ST_ABSWhat is already known on this topicC_ST_ABSComplement activation represents a substantial part of the overall biological activity of few therapeutic antibodies used in cancer immunotherapy. Factor H-related protein 4 can activate complement by serving as a platform for the assembly of alternative pathway C3 convertase by competing with factor H for C3b binding. We previously showed that multimeric recombinant proteins displaying the FHR4 complement effector moiety and a nanobody anti-HER2 targeting moiety selectively direct the activation of the complement alternative pathway on HER2-expressing tumor cells, leading to subsequent cell destruction through direct cell lysis or through the activation of host effector cells. What this study addsWe used in the current work a novel complement-directed tumor cell distruction strategy in vivo. We showed that CoMiX-FHR4 and CoMiX-Fc (based on triple Fc dimers), targeting HER2-positive breast tumor cells, inhibit tumor growth in a model of BT474 xenograft in NUDE mice by stimulating complement activation, BT474 death, NK cell activation, and phagocytosis of tumor cells by macrophages. CoMiX-FHR4 remain efficient in xenografts of BT474 cells resistant to trastuzumab. How this study might affect research, practice or policyWe demonstrate for the first time that directed complement activation on tumor cells is an alternative to therapeutic antibodies which is particularly promising when resistance to standard-of-care treatment occurs.

immunology↗

bioRxiv2022

Natural Killer activating Multimeric Immunotherapeutic compleXes (NaMiX) induce cytotoxic activity and killing of HIV-1 infected cells

HIV-1 persists in viral reservoirs of latently infected CD4+ T cells containing integrated replication-competent viral DNA. Combined Antiretroviral Therapy (cART) does not eradicate HIV-1 reservoirs and treatment interruption will ultimately lead to viral load rebound. HIV-1 infection dramatically reduces the proportion of functional NK cell subsets and increases the expression of the checkpoint inhibitors NKG2A and KIR2DL. In this regard, we developed novel recombinant molecules combining multimers of the IL-15/IL-15R complex with the single-chain fragment variables (scFvs) of NKG2A or KIR2DL, and named them as Natural killer activating Multimeric immunotherapeutic compleXes (NaMiX). NaMiX significantly improved the cytotoxic activity of NK cells against HIV-1 positive ACH-2 cells and resistant Raji cancer cells by increasing their degranulation capacity, release of granzyme B, perforin and IFN-{gamma} expression. Targeting the NKG2A receptor had a stronger effect compared to the targeting of the KIR2DL receptor due to its higher expression on NK cells. In a viral inhibition assay using CD4+ T cells from HIV-1 positive patients under cART, NaMiX initially increased viral replication which was subsequently inhibited by stimulated NK cells. In humanized NSG tg-huIL-15 mice showing functional NK cells, we observed enhanced activation, degranulation and killing by NK cells from the spleen of mice treated with anti-NKG2A NaMiX compared to the cells of control mice previously infected with HIV-1 and treated with cART. Although NaMiX did not delay viral load rebound after treatment interruption in a first attempt, it tend to decrease total HIV-1 DNA in the lungs of the mice. Blocking the inhibitory receptor NKG2A in combination with targeted multimers of IL-15 on NK cells could therefore be a promising immunotherapeutic strategy towards HIV-1 functional cure.

immunology↗

bioRxiv2022

Vaccine- and BTI-elicited pre-Omicron immunity more effectively neutralizes Omicron sublineages BA.1, BA.2, BA.4 and BA.5 than pre-Omicron infection alone

Since the emergence of SARS-CoV-2 Omicron BA.1 and BA.2, several Omicron sublineages have emerged, supplanting their predecessors. BA.5 is the current dominant sublineage. Here we compared the neutralization of Omicron sublineages BA.1, BA.2, BA.4 and BA.5 by human sera collected from individuals who were infected with the ancestral B.1 (D614G) strain, vaccinated (3 doses), or with hybrid immunity from vaccination (2 doses) followed by pre-Omicron breakthrough infection (BTI) with Gamma or Delta. All Omicron sublineages exhibited extensive escape from all sera compared to the ancestral B.1 strain and to Delta, albeit to different levels depending on the origin of the sera. Convalescent sera were unable to neutralize BA.1, and partly neutralized BA.2, BA.4 and BA.5. Vaccinee sera partly neutralized BA.2, but BA.1, BA.4 and BA.5 evaded neutralizing antibodies. BTI sera were either non-neutralizing or partially neutralizing. In this case, they had similar neutralizing ability against all Omicron sublineages. Despite similar levels of anti-Spike and anti-Receptor Binding Domain (RBD) antibody in all groups, BTI sera had the highest cross-neutralizing ability against all Omicron sublineages and convalescent sera were the least neutralizing. The NT50:antibody titer ratio, which reflects antibody avidity, was significantly higher in sera from BTI patients compared to convalescent sera, underscoring qualitative differences in antibodies elicited by infection alone and by vaccination. Together these findings highlight the importance of vaccination to trigger highly cross-reactive antibodies that neutralize phylogenetically and antigenically distant strains, and suggest that immune imprinting by first generation vaccines may restrict, but not abolish cross-neutralization.

immunology↗

bioRxiv2022

The anti-caspase 1 inhibitor VX-765 reduces immune activation, CD4+ T cell depletion, viral load and total HIV-1 DNA in HIV-1 infected humanized mice

BackgroundHIV-1 infection results in the activation of inflammasome involving NLRP3, IFI16, caspase-1 and release of IL-1 {beta} and IL-18. Early inflammasome activation may facilitate viral spread and establishment of the viral reservoir. We evaluated the effect of the caspase-1 inhibitor VX-765 on virological and immunological parameters after HIV-1 infection in humanized mice. MethodsNSG mice were engrafted with human CD34+ hematopoietic stem cells and were infected with HIV-1 JRCSF. 15 mice were first sacrificed serially to investigate kinetics of the HIV-1 related inflammasome activation. Infected mice (n=24) were then treated with VX-765 or vehicle from day 1 post infection for 21 days. Blood and organs were collected at different time points, and analysed for inflammasome genes expression, cytokines levels, viral load, CD4 cell count, and total HIV-1 DNA. ResultsExpression of caspase-1, NLRP3 and IL1-{beta} was increased in lymph nodes and bone marrow on day 1 and 3 post infection (mean fold change (FC) of 2.08, 3.23, and 6.05, p< 0.001 respectively between day 1 and 3). IFI16 expression peaked at D24 in lymph node and bone marrow (FC 1.49 and 1.64, p<0.05) and coincides with increased IL-18 levels in plasma (6.89 vs. 83.19 pg/ml, p=0.004). AIM2 and IFI16 expression correlated with increased viral load in tissues (p<0.005 for the spleen) and loss of CD4+ T cells percentage in blood (p<0.0001 for the spleen). Treatment with VX-765 significantly reduced TNF- at day 11 (0.47 vs. 2.2 pg/ml, p=0.045), IL-18 at day 22 (7.8 vs 23.2 pg/ml, p=0.04), CD4+ T cells (44.3% vs 36,7%, p=0.01) and the CD4/CD8 ratio (0.92 vs 0.67, p=0.005) in plasma. Importantly, viral load (4.26 vs. 4.89 log 10 copies/ml, p=0.027) and total HIV-1 DNA (1 054 vs. 2 889 copies /106 cells, p=0.029) were decreased in VX-765-treated mice as compared to vehicle-treated mice. Discussionwe report here an early inflammasome activation before detectable viral dissemination in humanized mice. We demonstrated that targeting inflammasome activation early after HIV-1 infection may represent a potential therapeutic strategy to prevent CD4+ T cell depletion as well as to reduce immune activation, viral load and the HIV-1 reservoir formation.

immunology↗