Biology subjects

Kerfelec, B.

Publications and source records attributed to Kerfelec, B..

3 recordsLinked to original sources

bioRxiv2025

Identification and optimization of trans-species reactive TfR1-binding VHH as tools for drug delivery across the blood brain barrier

The blood-brain barrier (BBB) is a major obstacle for delivering therapeutic agents to the central nervous system (CNS), posing significant challenges for treating neurological disorders. Among current strategies to improve brain drug exposure, hijacking physiological pathways involved in receptor-mediated transcytosis (RMT) has emerged as a promising strategy. While targeting transferrin receptor 1 (TfR1) is widely explored, many TfR1-antibodies lack cross-species reactivity, limiting translational development. In the present study, we identified and characterized camelid-derived single-domain antibodies (VHHs) with robust cross-reactivity to rodent, rhesus monkey, and human TfR1. Epitope mapping of the VHH revealed a novel binding site at the interface of the TfR1 dimer. When fused to a human IgG1 Fc domain, these VHHs, as monomers or homodimers, were efficiently internalized by engineered CHO cells and brain endothelial cells expressing TfR1 from different species. Systemic administration of VHH-Fc constructs in mice demonstrated significantly improved brain uptake compared to irrelevant controls. Functional delivery was confirmed using neurotensin (NT)-induced hypothermia, and we established correlations between in vivo effects and TfR1 VHH binding properties determined by surface plasmon resonance. Notably, efficient BBB transcytosis was associated with intermediate affinity and rapid dissociation rates. Engineered variants maintained favorable cross-species binding, including similar affinities to human and non-human primate TfR1, facilitating translational studies. The cross-reactive anti-TfR1 VHHs we developed offer a versatile and modular platform for CNS drug delivery and hold promise as molecular shuttles for transporting therapeutic agents across the BBB. Our work establishes a robust foundation for developing next-generation brain-targeted biotherapeutics, including peptides, enzyme replacement therapies, antibody-based treatments for neurodegenerative diseases, and oligonucleotide delivery for CNS disorders, enabling seamless translation from preclinical to clinical applications.

neuroscience↗

bioRxiv2024

Decoupling individual host response and immune cell engager cytotoxic potency

Immune cell engagers are molecular agents, usually antibody-based constructs, engineered to recruit immune cells against cancer cells and kill them. They represent a versatile and powerful tool for cancer immunotherapy. Despite the multiplication of new engagers tested and accepted in the clinics, how molecular and cellular parameters influence their action is poorly understood. In particular, disentangling the respective role of host immune cells and engager biophysical characteristics is needed to improve their design and efficiency. Focusing here on harnessing antibody dependent Natural Killer cell cytotoxicity, we measure the efficiency of 6 original bispecific antibodies (bsAb), associating an anti-HER2 nanobody and an anti-CD16 nanobody. In vitro cytotoxicity data using primary human NK cells on different target cell lines exposing different antigen densities were collected, exhibiting a wide range of bsAb dose response. In order to rationalize our observations, we introduce a simple multiscale model, postulating that the density of bsAb bridging the two cells is the main parameter triggering the cytotoxic response. We introduce two new microscopic parameters: the surface cooperativity describing bsAb affinity at the bridging step and the threshold of bridge density determining the donor-dependent response. Both parameters permit to rank Abs and donors and to predict bsAb potency as a function of antibodies bulk affinities and receptor surface densities on cells. Our approach thus provides a general way to decouple donor response from immune engagers characteristics, rationalizing the landscape of molecule design.

biophysics↗

bioRxiv2018

Nanobody-antigen catch-bond reveals NK cell mechanosensitivity

Antibodies are key tools in biomedical research and medicine. Their binding properties are classically measured in solution and characterized by an affinity. However, in physiological conditions, antibodies can bridge an immune effector cell and an antigen presenting cell, implying that mechanical forces apply to the bonds. For example, in antibody-dependent cell cytotoxicity, a major mode of action of therapeutic monoclonal antibodies, the Fab domains bind the antigens on the target cell, while the Fc domain binds to the activating receptor CD16 (also known as FcgRIII) of an immune effector cell, in a quasi bi-dimensional environment (2D). Therefore, there is a strong need to investigating antigen/antibody binding under force (2D), to better understand and predict antibody activity in vivo. We used two anti-CD16 nanobodies targeting two different epitopes and laminar flow chamber assay to measure the association and dissociation of single bonds formed between microsphere-bound CD16 antigens and surface-bound anti-CD16 nanobodies (or single domain antibodies), simulating 2D encounters. The two nanobodies exhibit similar 2D association kinetics, characterized by a strong dependence on the molecular encounter duration. However, their 2D dissociation kinetics strongly differ as a function of applied force: one exhibits a slip bond behaviour where off-rate increases with force; the other exhibits a catch bond behaviour with off-rate decreasing with force. This is the first time, to our knowledge, that catch bond behaviour was reported for antigen-antibody bond. We further exploit this property to show how Natural Killer cells spread differentially on surfaces coated with these molecules, revealing NK cells mechanosensitivity. Our results may also have strong implications for the design of efficient bispecific antibodies for therapeutic applications.

biophysics↗