Biology subjects

Nerreter, T.

Publications and source records attributed to Nerreter, T..

5 recordsLinked to original sources

bioRxiv2025

Single-molecule localization microscopy reveals the molecular organization of endogenous membrane receptors

Super-resolution microscopy in combination with genetic labeling methods allows imaging of single proteins in cells. However, visualizing endogenous proteins on primary cells remains challenging due to the use of sterically demanding antibodies for labeling. Here, we demonstrate how immunolabeling conditions and antibody crosslinking influence the quantification and identification of membrane receptor stoichiometry on cells using single-molecule localization microscopy. We developed an optimized immunolabeling and analysis protocol and demonstrate the performance of the approach by resolving the molecular organization of endogenous CD45, CD69, and CD38 on Jurkat T cells. To demonstrate the usefulness of the method for immunotherapy applications we investigated the interaction of primary multiple myeloma cells with the therapeutic monoclonal antibodies (mAbs) daratumumab and isatuximab, and a polyclonal anti-CD38 antibody. Our approach might lay the foundation for improved personalized diagnostics and treatment with therapeutic antibodies. One-Sentence SummarySingle-molecule localization microcopy quantifies the expression and resolves the stoichiometry of endogenous membrane receptors

biophysics↗

bioRxiv2025

A novel CAR T cell blend targeting PDPN and GD2 to overcome glioblastoma heterogeneity

BackgroundWhile chimeric antigen receptor (CAR) T cells have achieved encouraging remission rates in hematological malignancies, they demonstrated limited success in treating Glioblastoma (GBM), particularly due to high intra- and intertumoral heterogeneity. In this study, we identified a relevant and preserved target antigen, Podoplanin (PDPN), and evaluated the potential of a PDPN- and GD2-CAR T cell blend to overcome GBM heterogeneity. MethodsTarget antigen screening included clinical samples, healthy tissues and cell lines, as well as publicly available RNA sequencing datasets. The anti-tumor function of CAR T cells were examined in co-culture experiments with GBM cell lines and patient-derived organoids (PDOs), and in vivo after locoregional delivery in orthotopic xenograft models. ResultsThe generated CAR T cells demonstrated strong anti-tumor activity against several cell lines and PDOs from multiple patients. PDPN and GD2 expression was detectable in all PDOs at varying densities and regardless of the antigenic profile, the CAR T cell blend induced significantly higher levels of apoptosis in organoids than single antigen targeting counterparts. In vivo, we observed efficient tumor regression after locoregional administration of monospecific CAR T cells. While heterogeneous orthotopic tumors eventually relapsed in these groups, blended therapy resulted in a significantly increased overall survival and even achieved cure in the majority of mice. ConclusionThis novel PDPN-/GD2-CAR T cell blend demonstrated strong efficacy in advanced preclinical models of glioblastoma. The results suggest that this approach can overcome GBM heterogeneity in clinical application and address previous limitations of single antigen CAR T cell therapies. KEYPOINTSO_LIPDPN is a relevant and consistent CAR T cell target antigen in primary and recurrent GBM C_LIO_LIPDPN- and GD2-CAR T cells display synergistic anti-tumor activity in patient-derived organoids C_LIO_LILocal delivery of our CAR T cell blend confers long-term survival and cure in GBM-bearing mice C_LI IMPORTANCE OF THE STUDYThe highly variable landscape of tumor antigens in GBM represents a serious obstacle to single antigen CAR T cell therapies. In this study, we identified Podoplanin (PDPN) and GD2 as the most preserved target antigens in a screening campaign, with an even increased density in recurrent GBM compared to primary GBM. We combined PDPN- and GD2-CAR T cells in a blended treatment approach to counter antigen heterogeneity, and achieved a substantial gain in efficacy against patient-derived organoids (PDOs). In an orthotopic xenograft model, locoregional administration of the PDPN- and GD2-CAR T cell blend conferred long-term complete remission and increased survival compared to single antigen targeting. This study provides a hierarchy of CAR target antigens for treating GBM and illustrates the therapeutic potential of combinatorial antigen targeting using a PDPN/GD2-CAR T cell blend. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/636223v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@109a9aaorg.highwire.dtl.DTLVardef@16215faorg.highwire.dtl.DTLVardef@910623org.highwire.dtl.DTLVardef@129f79c_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGRAPHICAL ABSTRACT:C_FLOATNO C_FIG

immunology↗

bioRxiv2025

Autocrine glucocorticoid signaling in hormonally active cancer induces antigen expression for immunotherapy

Exogenous glucocorticoids (GCs) suppress T cell-based immunotherapy, yet the consequences of endogenous GCs produced or regenerated by tumours remain poorly understood. Here, we show that tumour-derived GCs couple immune evasion to therapeutic antigenicity. In adrenocortical carcinoma, autonomous GC production activates hGR-STAT3 signaling to increase the surface antigen ROR1. This creates an immunological paradox in which GC excess promotes therapeutic antigen expression while suppressing T cell-mediated antitumor activity. Selective hGR-knockout renders ROR1 CAR-T cells GC-resistant while preserving GC-driven ROR1 expression in tumor cells, resulting in durable tumor control in vivo. Non-endocrine pancreatic and triple-negative breast cancers recreate this circuit through HSD11B1-mediated GC recycling, which is further induced by CAR-T cell-derived cytokines under immune pressure. Thus, GC-resistant CAR-T cells exploit a tumor-derived endocrine program that couples immune suppression to therapeutic antigenicity.

cancer biology↗

bioRxiv2023

Mutation-specific CAR T cells as precision therapy for IGLV3-21R110 expressing high-risk chronic lymphocytic leukemia

The concept of precision cell therapy targeting tumor-specific mutations is appealing but requires surface-exposed neoepitopes, which is a rarity in cancer. B cell receptors (BCR) of mature lymphoid malignancies are exceptional in that they harbor tumor-specific-stereotyped sequences in the form of point mutations that drive self-engagement of the BCR and autologous signaling. Here, we used a BCR light chain neoepitope defined by a characteristic point mutation (IGLV3-21R110) for selective targeting of a poor-risk subset of chronic lymphocytic leukemia (CLL) with chimeric antigen receptor (CAR) T cells. We developed murine and humanized CAR constructs expressed in T cells from healthy donors and CLL patients that eradicated IGLV3-21R110 expressing cell lines and primary CLL cells, but not polyclonal healthy B cells. In vivo experiments confirmed epitope-selective cytolysis in xenograft models using engrafted IGLV3-21R110 expressing cell lines or primary CLL cells. We further demonstrate in two humanized mouse models lack of cytotoxicity towards human B cells. These data provide the basis for novel avenues of resistance-preventive and biomarker-guided cellular targeting of functionally relevant lymphoma driver mutations sparing normal B cells.

cancer biology↗

bioRxiv2023

CARs are organized in nanodomains in the plasma membrane of T cells that accumulate at tumor contact sites

Chimeric antigen receptors (CARs) are synthetic immune receptors that are expressed in T cells through genetic engineering. CAR-T cells have been successfully used to eradicate very advanced leukemias and lymphomas and their functional properties have been intensively studied. However, relatively little is known about the spatiotemporal expression and organization of CARs on the T-cell membrane and how this influences their efficacy. Here, we applied super-resolution microscopy to visualize CD19-, ROR1-, and ROR2-specific CARs in human CD4+ and CD8+ T cells that were engineered with lentiviral and transposon-mediated gene transfer. Our data show that the majority of CARs is organized in nanodomains virtually independent of the T cell type, CAR construct and expression level. Quantitative analyses revealed a slightly higher CAR density in transposon-engineered T cells correlating with higher antigen sensitivity and faster resolution of anti-tumor functions compared to lentivirally-engineered T cells. Live-cell fluorescence imaging revealed that both, CAR nanodomains and CAR monomers accumulate at tumor contact sites and form multifocal immunological synapses. Our study provides novel insights into the membrane organization of CARs with single-molecule resolution and illustrates the potential of advanced microscopy to inform the rational design of synthetic immune receptors for applications in immune cell therapy.

immunology↗