ECRT Projekte

The immune system harbors intrinsic capacity to fight malignancy. Tumor-specific T cells play a crucial role in combatting cancer by recognizing and killing malignant cells. To enhance tumor-specific immune responses, T cells can be redirected using genetically engineered receptors against tumor antigens. Clinical success of engineered chimeric antigen receptor (CAR)-T cell has been achieved for hematological malignancies. However, success of CAR-T cell therapy in treating solid tumors has been limited, since transferred CAR-T cells could not infiltrate and persist in the hostile tumor environment. To improve adoptive transfer of CAR-T cells against solid tumors, we initiated a study to learn from intrinsic cues that promote T cell infiltration and persistence in human solid tumors.

We joined forces with Karolinska Institutet and Umeå University (Sweden) to study solid cancer disease. Here, we unraveled chemotactic mechanisms in muscle-invasive bladder cancer (BC). BC is a solid tumor disease with poor prognosis, yet, T cell infiltration into the BC can resuscitate patients to reject the tumor. We addressed the question which signals in BC favor T cell trafficking to the tumor and intratumor expansion. In this approach, we identified a distinct Th1 chemokine (C1, see notes) as main driver of T cell infiltration at the tumor site. In-vitro, we found that protective T cell subsets expressed a C1-specific receptor variant (R1*) and functionally, R1*+ T cells enriched when targeted by the ligand C1. Strikingly, analyzing the novel R1*-C1 axis in the tumor, we could predict overall survival and successful response to therapy in BC-patients. We hypothesize that R1*-C1 is a T cell-activating pathway in cancer with therapeutic potential.

In this project, we continue this approach within our European translational group. We pursue two aims:

1) Understanding how C1 improves anti-tumor T cell function.

2) Setting up a new therapy via R1*+ CAR-T cells.

1) We want to test the use of C1 for in-vitro culture and potential clinical application. For this, we will study signaling induced by the R1*-C1 pathway by applying i) our established flow cytometry method on phosphorylation targets (e.g. STAT-proteins) ii) multiplex-mass cytometry (in-house available in the cytometry core facility) and iii) a unique DIGI-West approach (with Tübingen in the EU-network Reshape).

2) We address to select natively R1*-expressing T cells from human PBMC as a starting population for CAR-T cell production (nR1-CAR-T cells). Further, we plan to endow ex-vivo generated tumor-specific T cells with the genetically engineered receptor R1* (eR1-CAR-T cells). In addition, we intend to access HER2-specific CAR-T cell products that were previously applied against mamma carcinoma (with Baylor College of Medicine Houston, TX, USA). Here, we seek to verify if low expression of R1* in products correlates with poor response rates following adoptive therapy.

In this project, we aim to gain insights into the newly described R1*-C1 axis in human solid cancer by native pre-selection of R1*-expressing cells or R1*-engineering for CAR-T cell generation. Thereby, we employ novel therapeutic approaches to boost the efficacy of tumor-specific CAR-T cells to reach and survive in the solid cancer microenvironment.

Team: Tino Vollmer, Michael Schmück-Henneresse, Hans-Dieter Volk, Leila Amini, Jacqueline Wendering, Sarah Schulenberg

Funding: ECRT Research Grant

Redirecting T lymphocytes using chimeric antigen receptors (CARs) is a powerful tool in the emerging field of regenerative medicine. T cells reprogrammed to recognize and kill CD19 positive cancer cells dramatically improved leukemia and lymphoma treatment, whereas the transfer of CARs specific for allogeneic antigens (Ag) into regulatory T cells was shown to induce immune tolerance in transplantation models. Recent reports suggest CARs may facilitate innovative treatments for autoimmune diseases as novel receptor designs enable CAR-T mediated depletion of pathogenic auto-Ag specific B cells and prevent autoantibody (Ab) mediated diseases (1).

CARs are fusion proteins made of a target-specific extracellular domain (usually a single chain variable fragment derived from an Ab) and an intracellular signal transduction region (varying costimulatory domains and a CD3 zeta chain) which imitate T cell receptor (TCR) signaling. Optimal signaling strength of CARs is paramount for T cell activation and the clinical success, while binding affinity/avidity and minimal tonic signaling are also of importance (2). Surprisingly, careful evaluation of CAR signaling properties is rarely performed and no standardized assays have been described. Existing assays to predict in vivo CAR-T cell function are limited to tumor-specific CARs and rely on lengthy serial co-culture experiments. Thus, they are not practical for fast iterative optimization of CAR design.

We hypothesize that signaling properties of a given CAR can predict its in vivo performance. To this end, we plan to create a reporter cell line that generates an optical output in response to Ag-receptor signaling. In Jurkat cells, which are a standard model to study TCR signaling, the expression of a variety of genes is induced upon TCR ligation, some of which correlate exclusively and gradually with Ag-mediated TCR signaling strength.

To obtain a good reporter system, Jurkat cells will be genetically modified by inserting a reporter green fluorescent protein (GFP) transgene into a TCR-inducible gene via CRISPR/Cas9 (3). Ag-receptor (TCR or CAR) signaling will lead to the expression free GFP through the self-cleaving activity of a P2A linker (Fig. 1). CAR constructs to be tested can be readily transferred to the reporter cells via the delivery system of choice (retroviral, transposon, site-specific integration). After subsequent Ag stimulation, fluorescence intensity of CAR-mediated signaling will be detected by flow cytometry over multiple time points. Results from TCR/CD19 CAR signaling will serve as performance benchmarks.

We propose to name this platform FLECS as an acronym for Flow cytometric Evaluation of CAR Signaling. It will enable standardized mass-testing of new CAR constructs and ensure the selection of the most efficient CAR for any given Ag. It will be deposited in public cell banks and shared openly to advance CAR-redirected T cell therapy in regenerative medicine.

After establishing the FLECS platform, we will focus on the development of CARs for the severe, rapidly exacerbating, demyelinating, Multiple Sclerosis (MS)-like disease Neuromyelitis Optica (NMO). In NMO, auto-Abs against immunogenic self-Ag are thought to play a causative role. Similar to a recent report (1), we designed novel antigen receptors that incorporate the immunogenic epitope derived from the self-Ag to form a chimeric auto-Ab receptor (CAAR). Thus, cytotoxic T cells will be able to recognize B cells that display surface bound immunoglobulin (sIgG) specific for the auto-Ag (Fig.2). After FLECS analysis, the CAAR with best performance will be subjected to further functional analysis in vitro and in the mouse model. Eventually, targeted elimination of auto-Ag specific B cells may offer a novel therapeutic approach to prevent chronic inflammation through auto-Ab in NMO, while FLECS might facilitate the development of similar therapeutics for other autoimmune diseases.

Team: Dimitrios L. Wagner, Michael Schmück-Henneresse, Hans-Dieter Volk, Petra Reinke, Anja Hauser, Helena Radbruch, Jonas Kath

Funding: ECRT Research Grant

Aging is an irreversible, progressive process resulting in a decline of tissue functionality and its regenerative capacity. With an increasingly aged population in developed countries, understanding deviations in healing processes after injury in aged is key for developing novel treatment strategies. During life the body accumulates with cells which lack a proliferative capacity due to an irreversible cell cycle arrest which is termed cellular senescence. Senescent cells secrete a variety of pro-inflammatory cytokines which recruit immune cells for tissue clearance during development and to prevent cancer. Although this feature confers early-life benefits, the increasing pro-inflammatory environment contributes to late-life debility (Campisi 2013). This antagonistic function is even further emphasized by recent observations which not only show the accumulation of senescent cells within an injured tissue but that elimination of senescent cells delays wound healing in vivo (Demaria et al. 2014). While this investigation related the effect to the secretory phenotype, little is known how senescent cells directly contribute to tissue formation through ECM formation.

We investigated how the senescence program affects extracellular matrix deposition and tissue tension using a recently published in vitro wound healing model system (Brauer et al. 2019). We observed that cellular senescence strongly affected macroscopic tissue tension and fibrillar collagen secretion and assembly in an antagonistic manner. While senescence due to over-expression of cell cycle inhibitors (p16INK4/p21CIP) resulted in an increased contraction, DNA-damage-induced (Mitomycin C-treated) senescence strongly reduced tissue contraction. This indicates a direct and antagonistic role of cellular senescence in establishing tissue tension. Aside of the tensile state of the resulting ECM, cellular senescence also affected the biochemical composition via differential regulation of ECM proteins, e.g. collagen, fibronectin, decorin, and tenascin C. Furthermore, we found evidence that these macroscopic perturbations might be influenced by an altered mechanotransduction of senescent cells already on the single cell level (2D). The expression of integrins was altered correlating with an enlarged cell morphology and higher abundance of large focal adhesions particularly in cells that were driven into senescence by selective over-expression (p16/p21). How these two observations are linked remains so far unknown.

Based on these preliminary data, we propose a novel research question which we believe to be relevant and of high interest for a PhD project. Based on the understanding that senescent cells seem to strongly alter the extracellular niche we want to better understand the relevance of this finding for the in vivo tissue regeneration process. While the in vitro experiments focused on the behavior of a homogeneous population, senescent cells in vivo are found in relatively low abundance. We believe that senescent cells nevertheless impact the regeneration process and hypothesize that the ECM formed by senescent cells exhibits specific cell-instructive cues which influence cellular processes, e.g. migration, survival but also differentiation of surrounding stromal cells. A distinct matrix phenotype thereby might contribute to the impact senescent cells exert during tissue regeneration aside of their secretory phenotype. The PhD student will optimize a recently established procedure for decellularization in order to obtain cell-free ECM generated by senescent cells. The matrix will be used as a template for studying the cellular response both of fibroblasts and MSCs. Differences in ECM-dependent cellular behavior would support the hypothesis that an ECM created by senescent cells affects behavior of surrounding stromal cells. The student will further focus on the consequences of senescence-modulated cellular mechano-sensation on tissue formation. Starting from a basic description of cellular mechano-sensation, cellular organization will be studied on simplified geometries to describe differences in multi-scale cell organization (Werner et al. 2016). Finally collective cell organization, which leads to ECM formation, will be studied in more detail inside the established scaffold-based 3D tissue model to further understand the impact of senescent cells on early tissue regeneration.

Together, the results will contribute to a principle understanding of (i) how the resulting matrix properties steer the behavior of non-senescent through a distinct cell-instructive matrix code and (ii) how senescent cells sense and respond to their environment with regard of cell organization and tissue formation.

Team: Erik Brauer, Ansgar Petersen, Sven Geißler, Mina Sohrabi-Zadeh

Funding: ECRT Research Grant

Immuno-suppressive CD4+ regulatory T cells (Tregs) are the main natural preventer of auto-immune diseases and chronic inflammation and are known to support tissue regeneration after injury and immuno-pathology. Therefore, Tregs are currently being extensively studied as "living drugs" in adoptive cellular therapy against pathogenic inflammation and to foster tissue regeneration.

Classical approaches of adoptive Treg therapy, which are based on the extensive in vitro expansion of pre-existing Treg populations, are currently being hampered by several obstacles:

1) the acquisition of proliferation-induced cellular senescence during in vitro expansion resulting in limited survival;

2) a functional instability of Tregs during inflammatory conditions;

3) the absence of pre-existing functional Treg populations in certain auto-immune disease patients and

4) a lack of pre-existing Treg populations displaying the required antigen-specificity or migration capacity, as the antigen-specific T cells in auto-immune patients have acquired a (pathogenic) pro-inflammatory phenotype.

Our group is trying to address these limitations from a new molecular angle: from epigenetics. We have identified several critical epigenetic control elements ('Epi-stabilizers') in T cells which are involved in maintaining a given T cell phenotype (Durek et al, Immunity 2016). The best characterized one is the so-called 'Treg-specific demethylated region – TSDR' in the FOXP3 gene, which is determining Treg function and cellular identity (Huehn et al, Nat Rev Immunol., 2009). To date, the demethylated state of the TSDR is the most reliable biomarker for human Tregs.

Previous work in the group established a CRISPR/Cas9 based system of 'epigenetic editing' allowing the targeted switching of methylation states at Epi-stabilizer elements. With this, Epi-stabilizers can be switched on (=demethylation) and off (=methylation) at will. While this system was successful to switch DNA methylation states and with that, regulate expression of the associated gene, the functional phenotype of the T cells was not completely switched probably due to the remaining pre-imprinted T cell epigenetic landscape.

This is why I now suggest to take a small detour in the functional re-programming of T cell phenotypes and include a re-programming step towards induced pluripotent stem cells (iPSCs). During this, the original T cells can be rejuvenated (addresses obstacle 1 of current Treg therapy, above), while the original TCR can be maintained (obstacle 4). This approach would allow Treg therapy even in Treg-deficient patients (obstacle 3). The resulting iPSCs can be grown in virtually unlimited numbers without senescence acquisition (obstacle 1), are easy to manipulate by epi-/genetic editing and can be stored for repetitive transfusions if needed (obstacle 1). In addition, iPSCs can also be generated from other cellular sources but still be re-differentiated into T cells. The epigenetic editing will be introduced during the T cell differentiation step from iPSC-derived hematopoietic precursor cells, which mimics the normal T cell development in the thymus (7) and thus, is a promising approach to induce stable functional T cell subsets (obstacle 2).

With this project, we expect to establish a system, with which large numbers of storable, fully functional T cell populations can be generated displaying defined advantageous characteristics (e.g. functional stabilization, re-juvenation, selected TCR-specificity). This system can be extended to induce features like a defined migration behavior (obstacle 4) or cytokine expression profile, since Epi-stabilizers in homing receptor (Szilagyi et al., Mucosal Immunol., 2017; Pink et al., J Immunol., 2016) and cytokine genes (Lee et al., Immunity, 2006) have also been identified. With this, we assume to break down several road blocks on the way towards a successful clinical application of adoptive T cell therapies.

Team: Christopher Kressler, Julia Polansky-Biskup, Harald Stachelscheid, Marcel Finke

Funding: ECRT Research Grant

Team: Angélica Garciá Pérez, Mina Gouti, Markus Schülke, Lan Vi Nguyen

Funding: ECRT Research Grant

Oligodendrocytes constitute one of the four principal central nervous system (CNS) cell types - next to neurons, astrocytes and microglia. Oligodendrocytes form myelin sheaths around neuronal axons, ensuring efficient signal conduction in these axons. In Multiple Sclerosis (MS), a chronic immune-mediated demyelinating disease of unknown etiology, loss of myelin appears during both an initial relapsing-remitting phase and a subsequent secondary-progressive phase. The loss of myelin is associated with clinical disability, including pain, paralysis, vision loss and cognitive incline. Conversely, the generation of new myelinating oligodendrocytes and the repair of myelin, called oligodendrogenesis and remyelination respectively, are prerequisites for functional recovery. The pathological hallmark of MS is the presence of focal demyelinated lesions with partial axonal preservation and reactive astrogliosis. Focal demyelinated lesions can be partly or completely repaired by spontaneous remyelination. However, these regenerative processes are efficient only in a small subset of MS patients. Thus, for the development of highly effective remyelinating therapies it is particularly important to identify the factors that are suppressive or permissive of myelin regeneration.

While the determinants of lesion progression versus lesion repair in MS are still completely unknown, evidence points to the involvement of microenvironmental factors, including biomechanical and compositional extracellular matrix (ECM) properties. While past experimental approaches were often based on animal models, and have lead to the identification of a a few of individual ECM components as regulators of myelin repair. However, a fast growing body of conflicting data on the functional role of such singular components points to the necessity of a more holistic and human approach towards ECM-driven myelin regeneration:

In this project, we aim at identifying the correlative and causal relations between EMC mechanical as well as structural properties, ECM composition and the regenerative potential of human demyelinating and remyelinting MS lesions. Neuropathologically characterized human MS lesion tissue will be divided and subjected to 1) testing of biomechanical properties using microindentation together with structural characterization using label-free two-photon autofluorescence and second harmonic imaging and 2) decellularization of the ECM. The latter will allow us to study the lesion’s ECM as a whole without interference of cellular components. Isolated ECM will be again characterized for its biomechanical and structural properties and used as matrix for human myelinating stem cell cultures for the study of ECMmediated myelination efficiency. Stem cell fate and functional myelination studies will be performed in a microscopy based setting. These experiments will, for the first time, allow us to connect the biomechanical and structural properties of individual MS lesions and lesion-derived ECM with the efficiency of functional myelination in an ex vivo setting.

While we have broad insight into the promyelinating and myelin-supressive signaling effects of singular brain matrix components, nothing is known about the effect of the lesion ECM as a whole. Thus, in a next step, we aim at identifying the lesion type-specific ECM-mediated signaling pattern. Experimentally, we will look at phosphorylation patterns of multiple pro-oligodendrogenic and anti-myelinating signaling pathways on a single cell basis using high-contenct microscopy and advanced image analysis. Immunohistochemical and proteomic analysis of the individual decellularized lesion ECM will further enable us to characterize the different ECM components that underlie the individual biomechanical and regenerative properties. Lastly, through in vitro-mimicry studies, we aim at identifying which mechanical and biochemical properties may be used to functionally overcome brain ECM-associate inhibition of remyelination.

Taken together, through the integration of knowledge and methods from the fields of biomechanical engineering, biochemistry and regenerative cell biology, this project aims at characterizing key regulating brain ECM properties and identifying functional cellular regenerative mechanisms.

Team: Sarah-Christin Staroßom, Ansgar Petersen, Harald Stachelscheid, Erik Brauer, Juliana Campo Garcia, Roemel Jeusep Bueno

Funding: ECRT Research Grant

Due to the immunosuppressive therapy required for prevention of organ rejection after transplantation, some patients suffer from severe complications due to normally harmless chronic viral infections. Mostly potent anti-viral drugs can manage complications, however many of these bare toxicities, some patients are irresponsive or resistances can be developed. Thus, specific regeneration of the endogenous anti-viral immune response, without risking organ rejection by alloreactive T cells, by the means of adoptive anti-viral T cell therapy is an attractive alternative treatment. In some cases, our conventional approach of T cell therapy can only control the virus temporally, probably due to malfunctions of transferred T cells caused by the immunosuppressive therapy. Hence, we plan to generate T cells which are resistant to immunosuppressive treatment with widely used Tacrolimus for adoptive transfer. Tacrolimusresistant T cells shall be generated by knock out (k.o.) of the adapter protein FKBP12, which is required for the immunosuppressive function of Tacrolimus. The k.o. shall be achieved by a vector-free transfer of nucleoprotein complexes of the nuclease CRISPR associated protein 9 (Cas9) with a site-specific guide RNA by electroporation into virus-specific T cells. We plan to confirm specificity of the k.o. by sequencing of possible off target areas. Ultimately, we want to integrate resistance introduction into our GMP-conform protocol to facilitate clinical translation.

Team: Leila Amini, Dimitrios L. Wagner, Uta Rössler, Michael Schmück-Henneresse, Petra Reinke, Uwe Kornak, Daniel Kaiser, Andy Römhild, Ghazaleh Zarrinrad

Funding: Einstein Kickbox - Young Scientists & ECRT Research Grant

Little is known about the micro- and macro-structural changes in bone and their consequences on immune reconstitution in patients after hematopoietic stem cell transplantation (HSCT). We will study patients undergoing autologous (lymphoma/myeloma) and allogeneic (AML) HSCT. Both patient cohorts are treated with high-dose chemotherapy and are challenged with steroids, either before autologous HSCT as part of the standard treatment (lymphoma/ myeloma) or after allogeneic HSCT (AML) in case of graft-versus-host disease (GVHD). We have recently established high-resolution 3D-immunofluorescence bone imaging in experimental animal models. However, animal models of human tumors have important limitations and may not adequately reflect the clinical situation. Having immediate access to biopsies of HSCT patients, we are planning to apply the new imaging technique to bone biopsies from patients undergoing HSCT and to compare them to normal bone biopsies (e.g. from patients with malignant lymphoma at initial diagnosis and without BM manifestation). We will specifically investigate the bone micro-structure as well as the bone marrow niche for the physiological hematopoiesis and immune cells. In parallel, we will collect clinical data, such as cytopenia, chimerism, persistence of malignant cells, GVHD and infections. We will correlate the results of high-resolution 3D-immunofluorescence bone imaging with clinical characteristics, in order to identify clinically relevant structural changes in the bones.

Team: Il-Kang Na, Olaf Penack, Katarina Riesner, Sarah Mertlitz, Georg Duda, Katharina Schmidt-Bleek, Radost Anika Saß

Funding: Einstein Kickbox - Advanced Scientists & ECRT Research Grant

Tendon disorders can have diverse etiologies such as acute or chronic mechanical overload or enthesial autoimmunity & inflammation. Interestingly, although the causes are different the clinical outcome shows overlapping features with tendon degeneration and fibrosis. For autoimmune-mediated tendon disorders such as spondyloarthritis (SpA) the contribution of immune cell infiltration and activation is well accepted. For tendinopathies, due to chronic mechanical overload and tendon remodelling, infiltration of immune cells has been observed. Although the exact and especially individual pathology and the role of immune cells is far from being fully understood. With overlapping outcomes, it seems obvious that miscommunications between tenocytes and immune cells are shared pathomechanisms of these disorders. With the kick-box seed money we will start a comparative in depth analysis of immune cell composition and distribution applying multiplex immune histology. This will be continued within the three-year PhD project. Furthermore, we will dissect tenocyte & immune cell communications operational during healing upon acute injury as well as failed tendon regeneration in case of tendinopathy and enthesitis applying single cell RNA-seq. In future, elucidated signaling pathways and potential triggers driving tendon healing or degeneration will be investigated in tenocyte-immune cell co-cultures incorporating mechanical stimulation with the goal to identify novel therapeutic candidates.

Team: Birgit Sawitzki, Britt Wildemann, Franka Klatte-Schulz, Anja Kühl, Uta Syrbe, Martina Seifert, Christiane Gäbel

Funding: Einstein Kickbox - Advanced Scientists & ECRT Research Grant

Team: Arunima Murgai, Georgios Kotsaris, Max Von Kleist, Sigmar Stricker, Vikram Sunkara

Funding: ECRT Research Grant (short term of 3 months)

Team: Andreas Thiel, Christos Nikolaou, Demetrios Christou, Kerstin Wolk, Loyal Lucie, Roland Lauster

Funding: ECRT Research Grant (short term of 3 months)