Postdoctoral Scholar, VIB - Flanders Institute for Biotechnology (Belgium) (2021)

Doctor of Philosophy, University of Oxford (UK) (2019)

Stanford Advisors

All Publications

  • Fast and Efficient Genome Editing of Human FOXP3(+) Regulatory T Cells FRONTIERS IN IMMUNOLOGY Van Zeebroeck, L., Hornero, R., Corte-Real, B. F., Hamad, I., Meissner, T. B., Kleinewietfeld, M. 2021; 12: 655122


    FOXP3+ regulatory T cells (Tregs) are central for maintaining peripheral tolerance and immune homeostasis. Because of their immunosuppressive characteristics, Tregs are a potential therapeutic target in various diseases such as autoimmunity, transplantation and infectious diseases like COVID-19. Numerous studies are currently exploring the potential of adoptive Treg therapy in different disease settings and novel genome editing techniques like CRISPR/Cas will likely widen possibilities to strengthen its efficacy. However, robust and expeditious protocols for genome editing of human Tregs are limited. Here, we describe a rapid and effective protocol for reaching high genome editing efficiencies in human Tregs without compromising cell integrity, suitable for potential therapeutic applications. By deletion of IL2RA encoding for IL-2 receptor α-chain (CD25) in Tregs, we demonstrated the applicability of the method for downstream functional assays and highlighted the importance for CD25 for in vitro suppressive function of human Tregs. Moreover, deletion of IL6RA (CD126) in human Tregs elicits cytokine unresponsiveness and thus may prevent IL-6-mediated instability of Tregs, making it an attractive target to potentially boost functionality in settings of adoptive Treg therapies to contain overreaching inflammation or autoimmunity. Thus, our rapid and efficient protocol for genome editing in human Tregs may advance possibilities for Treg-based cellular therapies.

    View details for DOI 10.3389/fimmu.2021.655122

    View details for Web of Science ID 000691310000001

    View details for PubMedID 34408743

    View details for PubMedCentralID PMC8365355

  • CD70 expression determines the therapeutic efficacy of expanded human regulatory T cells COMMUNICATIONS BIOLOGY Hornero, R., Georgiadis, C., Hua, P., Trzupek, D., He, L., Qasim, W., Todd, J. A., Ferreira, R. C., Wood, K. J., Issa, F., Hester, J. 2020; 3 (1): 375


    Regulatory T cells (Tregs) are critical mediators of immune homeostasis. The co-stimulatory molecule CD27 is a marker of highly suppressive Tregs, although the role of the CD27-CD70 receptor-ligand interaction in Tregs is not clear. Here we show that after prolonged in vitro stimulation, a significant proportion of human Tregs gain stable CD70 expression while losing CD27. The expression of CD70 in expanded Tregs is associated with a profound loss of regulatory function and an unusual ability to provide CD70-directed co-stimulation to TCR-activated conventional T cells. Genetic deletion of CD70 or its blockade prevents Tregs from delivering this co-stimulatory signal, thus maintaining their regulatory activity. High resolution targeted single-cell RNA sequencing of human peripheral blood confirms the presence of CD27-CD70+ Treg cells. These findings have important implications for Treg-based clinical studies where cells are expanded over extended periods in order to achieve sufficient treatment doses.

    View details for DOI 10.1038/s42003-020-1097-8

    View details for Web of Science ID 000553151500001

    View details for PubMedID 32665635

    View details for PubMedCentralID PMC7360768

  • The Impact of Dietary Components on Regulatory T Cells and Disease FRONTIERS IN IMMUNOLOGY Hornero, R., Hamad, I., Corte-Real, B., Kleinewietfeld, M. 2020; 11: 253


    The rise in the prevalence of autoimmune diseases in developed societies has been associated with a change in lifestyle patterns. Among other factors, increased consumption of certain dietary components, such as table salt and fatty acids and excessive caloric intake has been associated with defective immunological tolerance. Dietary nutrients have shown to modulate the immune response by a direct effect on the function of immune cells or, indirectly, by acting on the microbiome of the gastrointestinal tract. FOXP3+ regulatory T cells (Tregs) suppress immune responses and are critical for maintaining peripheral tolerance and immune homeostasis, modulating chronic tissue inflammation and autoimmune disease. It is now well-recognized that Tregs show certain degree of plasticity and can gain effector functions to adapt their regulatory function to different physiological situations during an immune response. However, plasticity of Tregs might also result in conversion into effector T cells that may contribute to autoimmune pathogenesis. Yet, which environmental cues regulate Treg plasticity and function is currently poorly understood, but it is of significant importance for therapeutic purposes. Here we review the current understanding on the effect of certain dietary nutrients that characterize Western diets in Treg metabolism, stability, and function. Moreover, we will discuss the role of Tregs linking diet and autoimmunity and the potential of dietary-based interventions to modulate Treg function in disease.

    View details for DOI 10.3389/fimmu.2020.00253

    View details for Web of Science ID 000523705000001

    View details for PubMedID 32153577

    View details for PubMedCentralID PMC7047770

  • CD45RA Distinguishes CD4(+)CD25(+)CD127(-/low) TSDR Demethylated Regulatory T Cell Subpopulations With Differential Stability and Susceptibility to Tacrolimus-Mediated Inhibition of Suppression TRANSPLANTATION Hornero, R., Betts, G. J., Sawitzki, B., Vogt, K., Harden, P. N., Wood, K. J. 2017; 101 (2): 302-309


    Adoptive transfer of forkhead box protein (FOX)3 regulatory T (Treg) cells offers a promising strategy to reduce damage to an allograft by the recipient's immune system. Identification of cell surface markers sufficient to purify Treg cells expanded ex vivo to remove cellular contaminants requires optimization. Furthermore, the expanded Treg must be able to survive, expand, and suppress in allograft recipients exposed to immunosuppressants, such as tacrolimus (TAC). Reduced CD127 expression enhances identification of Treg in the human CD4CD25 population. CD45RA expression identifies naive CD4CD25 Treg with an enhanced stability of Treg phenotype.We combine an analysis of CD45RA, CD25, and CD127 expression to identify subpopulations of CD4CD127CD25 cells. Regulatory T cells were sorted according to expression of CD25 and CD45RA and expanded in the presence of a physiological relevant concentration of TAC. Regulatory T cell-specific demethylation region (TSDR) demethylation, FOXP3 expression, and suppression were analyzed.CD4CD127CD25CD45RA Treg cells had a stable TSDR demethylated FOXP3 phenotype after expansion whereas CD4CD127CD25CD45RA Treg cell lost the TSDR demethylated phenotype. CD45RA Treg had a greater capacity to suppress after expansion with TAC.Although CD45RA Treg retained a greater suppressive capacity when expanded with TAC, the marked loss of the TSDR demethylated status highlights the potential for loss of stability of these cells in transplant recipients treated with TAC based immunosuppression. We show that a population of CD4CD127CD45RA Regulatory T cell may offer the best compromise between susceptibility to loss of suppression when exposed to TAC and maintenance of a TSDR demethylated phenotype following in vitro expansion.

    View details for DOI 10.1097/TP.0000000000001278

    View details for Web of Science ID 000393647400024

    View details for PubMedID 28118317

    View details for PubMedCentralID PMC5265687