Molecular dissection of regulatory T cells

Regulatory T cells (Tregs) constitute a hurdle against effective anti-cancer immunity, but are useful in adjuvant therapy to mitigate graft versus host disease in leukemia patients receiving allogeneic stem cell grafts.
In this research line, we aim to better understand the fundamental properties of Tregs and to identify molecules or pathways that can be exploited to selectively manipulate regulatory T cells. Despite their opposite functions, regulatory and conventional T cells are closely related. Consequently, inhibition of one often also affects the other, diminishing net therapeutic outcome. To identify cell-type unique elements, we have defined signature proteomes of different Treg cell types, using label free shot gun mass spectrometry. These signatures provide leads for therapeutic manipulation. Genetic experiments are now performed to determine how signature proteins control Treg cell function and viability. Furthermore, we are performing phosphoproteomics, a mass spec-based proteome-wide signaling analysis technique,  to identify pathways that are different between regulatory and conventional T cells and therefore allow specific manipulation. This research line has yielded new insights into fundamental aspects of Treg cell biology (Cuadrado et al, manuscript submitted for publication). Furthermore, we believe it will open up new avenues for manipulation of these cells in cancer patients.

Title Memory and effector cell differentiation of T cells

T cells are potent transplantation products to help eradicate tumor cells. Several fundamental processes are critical for T cell responses against tumors. First, both CD4 and CD8 T cells must differentiate from naïve precursor cells into effector cells. Effector T cells must subsequently evade tolerance mechanisms mobilized by tumors to avoid rejection. Finally, memory cells must be generated to suppress cancer relapse caused by outgrowth of dormant tumor clones after primary tumors have been eliminated. In this research program, we study the molecular mechanisms that govern these processes. Special emphasis is on the role of the Notch signaling pathway. Without Notch activation, T cell responses are qualitatively impaired or even abortive. Activation of Notch opposes expression of inhibitory receptors such as PD1, Lag3 and CTLA4, which constitute hurdles to anti-tumor immune responses. We are developing strategies to mobilize this function of Notch, as these may be more efficacious to boost anti tumor responses than strategies directed at individual inhibitory receptors (such as anti PD1 antibodies).

T cells for adoptive cellular therapies 

In this research line we aim to develop T cells for adoptive cellular therapy. Two types of T cell products are currently under development:

1. Tumor infiltrating lymphocytes. These are T cells isolated from primary tumors, which are expanded in vitro and reinfused into patients. Promising results have been obtained with TILs in the treatment of melanoma patients. Together with the Wolkers and Spaapen labs, the Laboratory for Cellular Therapy at Sanquin and physicians at the NKI, we are now generating TILs from other tumor types (lung, kidney, prostate) and designing novel expansion protocols to improve the quality of the TILs. As an preclinical test system, we are developing a mouse model, in which human T cell responses can be examined in vivo. To this end, we are making use of MISTRG mice, which allow for superior reconstitution of a human immune system due to genetic replacement of critical human immune response genes.
2. Anti-viral T cells. Viral infections are a life threatening complication in patients during the immune-compromised phase after transplantation. Adoptive transfer of virus-specific T cells can be used to treat these patients. This approach is restricted to serostatus positive stem cell donors, whose blood contains memory T cells against these viruses. Here, we aim to develop a solution for patients receiving grafts from seronegative donors. We are studying whether partially HLA-matched purified multi-virus-specific T-cells from peripheral blood of third party healthy donors can be used to bridge the immune deficient period until patients are capable of developing endogenous anti-viral immune responses. Eventually, a library of characterized blood donors will be generated from the Sanquin repository whence virus specific T cells can swiftly be isolated and transferred into patients.

Key publications

• Cuadrado E., van den Biggelaar M., de Kivit S., Chen Y.,Slot M, Doubal I, Meijer A, van Lier RAW, Borst J. and Amsen D. Proteomic Analyses of Human Regulatory T Cells Reveal Adaptations in Signaling Pathways that Protect Cellular Identity. (2018) Immunity. 2018 May 15;48(5):1046-1059
• Backer RA., Hombrink P., Helbig C., and Amsen D., The fate choice between effector and memory T cell lineages: asymmetry, signal integration and feedback to create bistability (2018). Advances in Immunology 37:43-82. doi: 10.1016/bs.ai.2017.12.003.
• KleinJan, A., Tindemans, I., Montgomery, J.E., Lukkes, M.,, de Bruijn, M.J.W., van Nimwegen M., Bergen,I.,Moellering, R.E., Hoogsteden, H.C., Boon, L., Amsen, D. and Hendriks, R.W. The Notch Pathway Inhibitor SAHM1 Abrogates the Hallmarks of Allergic Asthma (2017). JACI, doi: 10.1016/j.jaci.2017.08.042.
• Hombrink, P., Helbig, C., Backer, R.A., Piet, B. , Oja A.E., Stark, R., Brasser, G., Jongejan, A., Jonkers, R.E., Nota, B., Basak, O., Clevers, H.C., Moerland, P.D*., van Lier, R.A.*, and Amsen, D¹*. (¹corresponding author and *equal contribution senior author). Programs underlying persistence, vigilance and control of human CD8+ lung resident memory T cells (2016). Nature Immunology, 2016 Dec;17(12):1467-1478.
• Amsen, D., Helbig, C., and Backer, R.A. Notch in T cell differentiation: all things considered. (2015). Trends in Immunology, 36(12):802-14.