Biology subjects

McCallion, O.

Publications and source records attributed to McCallion, O..

4 recordsLinked to original sources

bioRxiv2025

Redefining the topology of the human bone marrow using augmented spatial transcriptomic analysis

The bone marrow (BM) is the main site of haematopoiesis in adult life. Our understanding of the pathogenesis of BM-derived blood cancers is limited by lack of spatial contextualisation. While emerging spatial transcriptomic (ST) platforms offer unprecedented opportunities for spatially-resolved cellular phenotyping, we recognise and incorporate the power of AI-based tissue feature detection to enhance ST workflows. We perform ST analysis to define the topology of the normal bone marrow (BM) and BM in myeloproliferative neoplasms (MPNs), profiling 5,104,452 cells across 30 human BM samples. Following rigorous histology-based QC, we identify spatially-restricted trajectories of haematopoiesis and extend our understanding of the haematopoietic stem cell (HSC) niche. We find that BM fibrosis in MPN is associated with expansion of distinct immune and stromal co-enriched cell neighbourhoods. We then present a machine learning (ML)-based model trained on ST data that quantifies BM microenvironmental deviation, identifying heretofore unrecognised inter- and intra-individual sample heterogeneity in MPN. Our study demonstrates the potential for AI-based augmented ST analysis, and redefines our understanding of human BM topology.

cancer biology↗

bioRxiv2025

Clinical development of gene edited tacrolimus-resistant Treg (FKBP12KO-Treg) to enable simultaneous immunosuppression and support of immune regulation

Background: Unwanted immune responses play a central role in the pathogenesis of solid organ allograft rejection. These are managed by life-long immunosuppression with considerable burden for the patient and society. Adoptive therapy with regulatory T-cells (Treg) is a promising approach to restore sustainable immune balance and avoid long-term adverse effects of immunosuppression. While Treg effectively inhibit activation of unwanted immune responses, they are less effective in controlling pre-existing/activated memory effector T-cells (Teff). Thus, co-administration of Treg with immunosuppressants is required to achieve a sustainable organ acceptance. Calcineurin inhibitors (CNI) are powerful in controlling de novo generated and preformed Teff. However, CNI also dampen Treg immunoregulatory function. Thus, we hypothesize improved results of adoptive Treg therapy in immunosuppressed patients applying tacrolimus-resistant Treg. Methods: While retaining CNI modulation of Teff with tacrolimus, we knocked-out FKBP12 in Treg (FKBP12KO-Treg) by gene-editing using ribonucleoprotein-based CRISPR/Cas9 technology to generate tacrolimus-resistant Treg and characterised them using flow cytometry, functional assays and in-depth phenotyping. Results: This detailed in vitro analysis showed FKBP12KO-Treg were comparable to non-gene edited Treg and impervious to tacrolimus while maintaining immunoregulatory function and sensitivity to alternative CNIs raising no safety concerns. Furthermore, we aligned our methodology to achieve GMP compliance laying the basis for a manufacturing license in preparation of a clinical trial. Conclusion: Based on the presented preclinical dataset implying safety and efficacy of FKBP12KO-Treg, we are now seeking to undertake a proof-of-concept clinical trial to evaluate the co-administrationof FKBP12KO-Treg and tacrolimus to enhance the management of living donor kidney transplant recipients.

immunology↗

bioRxiv2024

Gene editing of CD3 epsilon gene to redirect regulatory T cells for adoptive T cell transfer

I.Adoptive transfer of regulatory T cells (Tregs) is a promising strategy to combat immunopathologies in transplantation and autoimmune diseases. Antigen-specific Tregs are more effective in modulating undesired immune reactions, but their low frequency in peripheral blood poses challenges for manufacturing and their clinical application. Chimeric antigen receptors (CARs) have been used to redirect the specificity of Tregs, employing retroviral vectors. However, retroviral gene transfer is costly, time consuming, and raises safety issues. Here, we explored non-viral gene editing to redirect Tregs with CARs, using HLA-A2-specific constructs for proof-of-concept studies in transplantation models. We introduce a virus-free CRISPR-Cas12a approach to integrate an antigen-binding domain into the CD3 epsilon (CD3{varepsilon}) gene, generating Tregs expressing a T cell receptor fusion construct (TruC). These CD3{varepsilon}-TruC Tregs exhibit potent antigen-dependent activation while maintaining responsiveness to TCR/CD3 stimulation. This enables preferential enrichment of TruC-redirected Tregs via repetitive CD3/CD28-stimulation in a GMP-compatible expansion system. Non-viral gene edited CD3{varepsilon}-TruC Tregs retained their phenotypic, epigenetic, and functional identity. In a humanized mouse model, HLA-A2-specific CD3{varepsilon}-TruC Tregs demonstrate superior protection of allogeneic HLA-A2+ skin grafts from rejection compared to polyclonal Tregs. This approach provides a pathway for developing clinical-grade CD3{varepsilon}-TruC-based Treg cell products for transplantation immunotherapy and other immunopathologies.

immunology↗

bioRxiv2023

Matching or genetic engineering of HLA Class I and II facilitates successful allogeneic 'off-the-shelf' regulatory T cell therapy

The potential to harness regulatory T cells (Tregs) for the treatment of autoimmune diseases and transplant rejection has been restricted by several barriers: donor variability, manufacturing complications, and time-consuming expansion processes. These issues further complicate the use of autologous Tregs during acute disease phases or when Tregs are low in number or dysfunctional. Here we explore the potential of off-the-shelf allogeneic Tregs, from healthy donors or universal sources, to provide a more practical solution. We discover that the efficacy of these cells is undermined by the recipients immune response, and that that rigorous matching of HLA classes I and II overcomes this barrier. Importantly, genetically manipulating HLA expression enables the use of unmatched allogeneic Tregs with in vivo efficacy. Our findings underscore the transformative potential of HLA-engineered Tregs, offering a novel, ready-to-use therapeutic avenue for treating a wide array of inflammatory diseases. One-Sentence SummaryMatching or engineering of HLA-I and HLA-II facilitates allogeneic off-the-shelf regulatory T cells for immunoregulation.

immunology↗