T cell subsets underlying the rise, fall and recall of the Germinal Center

Project Information

GC T Subsets

Grant agreement ID: 101042650

DOI

10.3030/101042650

EC signature date 16 March 2022

Start date 1 September 2022

End date 31 August 2027

Funded under

• European Research Council (ERC)

Total cost

€ 2 129 247,00

EU contribution

€ 2 129 247,00

Coordinated by

UNIVERSITETET I OSLO
Norway

Periodic Reporting for period 1 - GC T Subsets (T cell subsets underlying the rise, fall and recall of the Germinal Center)

Reporting period: 2022-09-01 to 2025-02-28

Summary of the context and overall objectives of the project

The COVID-19 pandemic has underscored significant gaps in our understanding of how durable immunity to rapidly mutating pathogens is established. This immunity is orchestrated within germinal centers (GCs), which are specialized microenvironments where B cells undergo somatic hypermutation, clonal selection, and affinity maturation. These processes result in the generation of high-affinity plasma cells and memory B cells, capable of neutralizing recurring infections and adapting to evolving pathogens. Central to the GC reaction are follicular helper T (Tfh) cells, which facilitate critical cognate interactions with B cells. However, emerging research has identified additional GC-resident T cell subsets with regulatory functions, dynamically influencing GC longevity and termination.
We have previously shown that GC-resident helper T cells can acquire regulatory phenotypes that shape the quality of B cells, impacting antibody diversity and functionality. These findings highlight the importance of understanding how distinct T cell subsets mediate either help or suppression within GCs, driving the differentiation of B cells into high-affinity plasma cells or long-lived memory B cells. This knowledge has profound implications for developing vaccines aimed at eliciting broadly neutralizing antibodies (bnAbs), essential for combating pathogens such as HIV, influenza, and Plasmodium. Additionally, elucidating the molecular pathways governing helper and suppressive T cell functions in GCs provides valuable insights into autoimmune diseases and chronic inflammation, informing the development of T cell-based therapeutic strategies.
Current approaches fail to address the multifaceted roles of T cell subsets within the GC. This ERC StG project aims to uncover the determinants of T cell heterogeneity and their molecular mechanisms, with a specific focus on their impact on B cell quality and antibody functionality.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

In the initial phase of this project, substantial scientific and technical progress has been achieved. Key advancements include elucidating how T cells regulate germinal center (GC) reactions via interaction-driven control mechanisms. This has been accomplished through studies utilizing novel tools for dissecting interaction-driven control of GC cellular subsets, as detailed in the initial project description. In the process, a state-of-the-art intravital two-photon microscopy platform—the first in the country and funded by the ERC StG—was established at the University of Oslo. This advanced imaging system provides high-resolution, spatiotemporal insights into GC T cell dynamics in response to pathogenic challenges.
A novel method for generating monoclonal TCR knock-in mice was developed using AAV and CRISPR/Cas9 genome editing. This transformative approach offers a more efficient, precise, and rapid strategy for creating functional monoclonal TCR mouse models, ensuring physiological TCR expression and accurate T cell differentiation. This significant improvement over traditional transgenic techniques has facilitated the expedited generation of multiple models critical to this project.
Additionally, a GC-driven platform for optimizing therapeutic monoclonal antibodies was established. Leveraging insights into somatic hypermutation and clonal selection within GCs gained during the project period, this system enables the efficient generation of high-affinity therapeutic antibodies targeting challenging antigens.
Overall, this phase has advanced the understanding of T and B cell biology while implementing innovative methodologies grounded in insights gained during this period.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Key Results: GC T cell biology insights from using a novel framework, dissecting contact-mediated control by immune synapse labeling. Germinal Center-Driven Affinity Optimization: Development of a novel platform that utilizes natural somatic hypermutation (SHM) and clonal selection in germinal centers to enhance monoclonal antibody (mAb) affinity. This method circumvents the inefficiencies of traditional methods and enables the generation of monoclonal therapeutic antibodies to elusive targets, such as carbohydrate antigens found in invasive fungal strains. The method presents a novel platform for the generation of therapeutic antibodies. The needs for further development are intellectual property rights (IPR) support and, importantly, support and continued expansion of the Norwegian Transgenic Center (NTS). Development of Knock-In T Cell Models: We have developed a method for rapidly generating monoclonal TCR knock-in mice. Our approach enables the rapid generation of monoclonal TCR mice with physiological TCR expression, providing a transformative tool for studying T cell development, antigen-specific immunity, and disease models. Importantly, this enables the rapid generation of multiple transgenic models for the project. Needs: continued support and expansion from the Norwegian Transgenic Center.