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Bortolatto, J.

Publications and source records attributed to Bortolatto, J..

5 recordsLinked to original sources

One-step generation of TCR knock-in mice targeted to the TCRβ locus results in functional mature T lymphocytes

Transgenic mouse models expressing predefined T cell receptors (TCRs) have been instrumental in advancing our understanding of T cell biology. However, these traditional models rely on random genomic insertion of large constructs, require labor-intensive embryo manipulation, and frequently result in aberrant TCR expression and phenotypes. These limitations render TCR transgenic models insufficient to meet the mounting demands for rapid and precise model systems to evaluate TCR specificities. To address these challenges, we developed a streamlined method that combines Adeno-Associated Virus (AAV), coupled with CRISPR/Cas9 genome editing to precisely integrate pre-rearranged TCR/{beta} sequences into the mouse Trb locus, enabling the rapid generation of first-of-its-kind TCR knock-in mice with physiological TCR expression and functional T cell differentiation. This approach bypasses the need for technically advanced embryo manipulation and enables rapid generation of models through a universally optimized AAV vector system, significantly enhancing the versatility and utility of monoclonal TCR mice in basic immunology and preclinical research such as cancer immunotherapy and vaccine development, providing a transformative resource to accelerate discovery and translation across disciplines.

immunology↗

Antibody-mediated feedback modulates interclonal competition in the germinal center

Serum antibodies from prior immune responses regulate B cell activation and germinal center (GC) access upon recall immunization. However, how antibodies produced by an ongoing immune response influence the outcomes of contemporaneous GCs is less clear. To explore this, we developed mouse models enabling the targeted ablation of plasma cells and antibodies produced by an immune response of interest, without affecting those produced homeostatically or by prior antigen encounters. Our findings show that, whereas antibody-mediated feedback is not required for affinity maturation, it can influence competition between B cells with different epitope specificities, specifically by reducing the abundance of clones that recognize the same epitopes as circulating antibodies. This modality of feedback represents a mechanism by which antibody responses can influence epitope specificity in ongoing GCs. These findings may therefore have implications for vaccination strategies aimed at steering clonal selection towards desired epitopes on complex antigens.

immunology↗

Replaying germinal center evolution on a quantified affinity landscape

Darwinian evolution of immunoglobulin genes within germinal centers (GCs) underlies the progressive increase in antibody affinity following antigen exposure. Whereas the cellular mechanics of how competition between B cells produces increases in affinity are well established, the evolutionary dynamics of this process are less clear. We developed an experimental evolution model where we "replay" over one hundred monoclonal GC reactions, assigning affinities to each cell using deep mutational scanning. Our data reveal how GCs achieve predictable outcomes by means of noisy but persistent selection on an affinity landscape whose exploration is heavily constrained by somatic hypermutation biases. We infer a fitness landscape that quantitatively recapitulates the affinity maturation trajectory of our clone and find that apparent features of GC selection such as permissiveness to low-affinity lineages and rapid plateauing of affinity are likely artifacts of survivorship biases that distort our view of how B cell affinity progresses over time.

immunology↗

Proximity-dependent labeling identifies dendritic cells that prime the antitumor CD4+ T cell response

Dendritic cells (DCs) are uniquely capable of transporting tumoral antigens to tumor-draining lymph nodes (tdLNs), and also interact with effector T cells within the tumor microenvironment (TME) itself, mediating both natural antitumor immunity and the response to checkpoint blockade immunotherapy. Using LIPSTIC (Labeling Immune Partnerships by SorTagging Intercellular Contacts)-based single-cell transcriptomics, we identify individual DCs capable of presenting antigen to CD4+ T cells in the tdLN as well as inside the tumor microenvironment (TME). Our findings reveal that DCs with similar hyperactivated transcriptional phenotypes interact with helper T cells both within tumors and in the tdLN, and that checkpoint blockade drugs enhance these interactions. These findings show that a relatively small fraction of DCs is responsible for most of the antigen presentation within the tdLN and TME to both CD4+ and CD8+ tumor-specific T cells and that classical checkpoint blockade enhances CD40-driven DC activation at both sites.

immunology↗

Vγ usage distinguishes pro- and anti-tumor intestinal γδ T cell subsets

{gamma}{delta} T cells physiologically scan the intestinal epithelium, representing a substantial fraction of infiltrating lymphocytes in colorectal cancer (CRC), albeit their role in CRC remains unclear. Using murine CRC models, we found that most {gamma}{delta} T cells in pre- or non-tumor colon express V{gamma}1+ or V{gamma}7+ and exhibit a cytotoxic profile. Targeting these {gamma}{delta} T cell subsets, as well as conditionally interfering with {gamma}{delta} T cell function at early stages of tumorigenesis led to heightened tumor development, suggesting anti-CRC functions for V{gamma}1+ and V{gamma}7+ subsets. In contrast, ROR{gamma}t+ {gamma}{delta} T cell subsets, including V{gamma}4+ and microbiotadependent V{gamma}6+, accumulated during CRC progression. Conditional deletion of ROR{gamma}t or V{gamma} chains revealed redundant roles for IL-17-producing V{gamma}4+ and V{gamma}6+ {gamma}{delta} T cells in promoting tumor growth. Our results uncover pro- and anti-tumor roles for {gamma}{delta} T cell subsets.

immunology↗