Biology subjects

Beppler, C.

Publications and source records attributed to Beppler, C..

5 recordsLinked to original sources

bioRxiv2026

Aging restricts maturation of CXCL13+ T follicular helper cells in human immunity

A decline in specific antibody responses is a hallmark of human aging, yet the differential contributions of B and T lymphocytes and their interactions remain unclear. CXCL13 is a critical chemokine that shapes germinal center organization, but the regulation of human-specific CXCL13+ Tfh cells during aging is not known. Using human tonsil organoids, single-cell RNA sequencing, and CRISPR perturbations, we mapped age-associated changes in T follicular helper (Tfh) cells, the cell type that provides T cell "help" to B cells in germinal centers (GCs). Tonsil organoids from older donors generated weaker influenza-specific antibody responses, which we traced to Tfh cell defects rather than B cells. Single-cell profiling revealed a selective loss of mature CXCL13 GC-Tfh cells accompanied by accumulation of Tfh precursor states. Trajectory analysis showed that aging arrests Tfh cell maturation at the early activated precursor transition, and CRISPR perturbations identified BACH2 and SOX4 as transcriptional regulators of differentiation reduced with age. These findings reveal a human-specific mechanism of immune aging with implications for strategies to restore humoral immunity.

immunology↗

bioRxiv2026

Fetal Thymic Expression Defines the Immunogenicity of Tumor Associated Antigens

Tumor associated antigens (TAAs) are promising targets for cancer immunotherapy, yet their immunogenicity varies widely and remains poorly understood. Here, we show that the immunogenic potential of TAAs is largely shaped by their expression in the thymus, likely established during fetal development. By integrating single-cell transcriptomic data across fetal and postnatal thymic epithelial cells (TECs), we find that TAA expression in fetal TECs predicts both in vitro CD8 T cell immunogenicity and the immune pressure against TAAs that occurs clinically in patients treated with immune checkpoint inhibitors. Notably, CD8 T cells recognizing TAAs highly expressed in the fetal thymus exhibit attenuated transcriptional, signaling, and metabolic responses even in the naive state, consistent with a tolerogenic imprinting imparted during thymic development and selection. Further, fetal thymic expression of TAAs can be leveraged to prioritize candidate targets for therapeutic use. These findings provide a biologic basis for the extreme variability seen in TAA immunogenicity and define guiding principles for rational antigen selection to drive the next generation of effective TAA-targeted immunotherapies.

immunology↗

bioRxiv2022

T cells use distinct topological and membrane receptor scanning strategies that individually coalesce during receptor recognition

During immune surveillance, CD8 T cells scan the surface of antigen presenting cells using dynamic microvillar palpation and movements as well as by having their receptors pre-concentrated into patches. Here, we use real-time lattice light sheet microscopy to demonstrate the independence of microvillar and membrane receptor patch scanning. While T cell receptor (TCR) patches can distribute to microvilli, they do so stochastically and not preferentially as for other receptors such as CD62L. The distinctness of TCR patch movement from microvillar movement extends to many other receptors that form patches that also scan independently of the TCR. An exception to this is the CD8 co-receptor which largely co-migrates in patches that overlap with or are closely adjacent to those containing TCRs. Microvilli that assemble into a synapse contain various arrays of the engaged patches, notably of TCRs and the inhibitory receptor PD-1, creating a pastiche of occupancies that vary from microvillar contact to contact. In summary, this work demonstrates that localization of receptor patches within the membrane and on microvillar projections is stochastic prior to antigen detection and that such stochastic variation may play into the generation of many individually-composed receptor patch compositions at a single synapse. Significance statementMotile T cell microvilli palpate surfaces to facilitate surface scanning in a pattern that is independent of the movement of pre-formed patches of transmembrane antigen-receptors across those microvilli; once T cell receptors engage, the microvilli act to scaffold multiple receptors within a microvillar close-contact.

immunology↗

bioRxiv2021

Imaging-guided fine tuning of CAR synapse dynamics and T cell triggering

T cells typically recognize their ligands using a defined cell biology - the scanning of their membrane microvilli to palpate their environment - while that same membrane scaffolds T cell receptors (TCRs) that can signal upon ligand binding. Chimeric antigen receptors (CARs) present both a therapeutic promise as well as a tractable means to study the interplay between receptor affinity, microvillar dynamics and T cell function. CARs are often built using single-chain variable fragments (scFvs) with far greater affinity than that of natural TCRs. We used high resolution lattice lightsheet (LLS) and total internal reflection fluorescence (TIRF) imaging to visualize microvillar scanning in the context of variations in CAR design. This demonstrated that conventional CARs hyper-stabilized microvillar contacts relative to TCRs. Reducing the affinity and/or avidity of binding brought synapse microvillar dynamics into natural ranges, normalized synapse resolution and improved downstream effector function. This work highlights the importance of understanding the underlying cell biology when designing receptors for optimal antigen engagement.

immunology↗

bioRxiv2019

Tumors Exploit Dedicated Intracellular Vesicles to Program T cell Responses

In order to drive productive tumor-infiltrating lymphocyte (TIL) function, myeloid populations must direct antigens to the lymph node, including to resident antigen-presenting cells (APCs) that have never touched the tumor. It has long been supposed that APCs trade antigens with one another, but the dominant cell biology underlying that remains unknown. We used in vitro and in vivo assays together with lattice light sheet and multiphoton imaging to show that myeloid cells carry tumor antigen-laden vesicles that they trade with one another as they reach distant sites. This accounts for the majority of antigen displayed to T cells and provides tumors with a mechanism to access APCs that differentially direct T cell activation away from memory phenotypes. This work defines efficient cell biology that drives the first steps of TIL generation and represents a new frontier for engineering tumoral immunity.

immunology↗