Biology subjects

Di Roberto, R. B.

Publications and source records attributed to Di Roberto, R. B..

7 recordsLinked to original sources

bioRxiv2024

Drug-controlled CAR-T cells through the regulation of cell-cell interactions

CAR T-cell therapy is constrained by on-target, off-tumor toxicities as well as cellular exhaustion due to chronic antigen exposure. CARs comprising small-molecule controlled switches can enhance both safety and therapeutic efficacy but are limited by the scarcity of non-immunogenic protein elements responsive to non-immunosuppressive, clinically approved drugs with favorable pharmacodynamics. Here, we combine rational design and library-based optimization of a protein-protein interaction (PPI) of human origin to develop venetoclax-controlled Drug-Regulated Off-switch PPI (DROP)-CARs. DROP-CARs enable dose-dependent release of the tumor-targeting scFv and consequent T-cell dissociation from the target tumor cell. Additionally, we present proof-of-concept for a dual DROP-CAR controlled by different small molecules, as well as for logic-gated synthetic receptors enabling STAT3 signaling. We demonstrate in vitro and in vivo function of DROP-CAR T cells and conclude that the approach holds promise for clinical application.

synthetic biology↗

bioRxiv2023

A Proximal Sox2 Enhancer Cluster is Required for the Anterior Regional Identity of Neural Progenitors

Embryonic development depends on spatially and temporally orchestrated gene regulatory networks. Expressed in neural stem and progenitor cells (NSPCs), the transcription factor sex-determining region Y box 2 (Sox2) is critical for embryogenesis and stem cell maintenance in neural development. Whereas Sox2 is regulated by a distal cluster of enhancers in embryonic stem cells (ESCs), enhancers closer to the gene have been implicated in Sox2 transcriptional regulation in the neural lineage. Using functional genomics data, and deletion analysis we show that a downstream enhancer cluster regulates Sox2 transcription in NSPCs derived from mouse ESCs. By generating allelic mutants using CRISPR-Cas9 mediated deletions, we show that this proximal enhancer cluster, termed Sox2 regulatory regions 2-18 (SRR2-18), is a cis regulator of Sox2 transcription during neural differentiation. Transcriptome analyses demonstrate that loss of even one copy of SRR2-18 disrupts the region-specific identity of NSPCs. Biallelic deletion of this Sox2 neural enhancer cluster causes reduced SOX2 protein, less frequent interaction with transcriptional machinery, and leads to perturbed chromatin accessibility genome-wide further affecting the expression of neurodevelopmental and anterior-posterior regionalization genes. Furthermore, homozygous NSPC deletants exhibit self-renewal defects and impaired differentiation into cell types found in the brain. Altogether, our data define a cis-regulatory enhancer cluster controlling Sox2 transcription in NSPCs and highlight the sensitivity of neural differentiation processes to decreased Sox2 transcription, which influences their differentiation into posterior neural fates, specifically the caudal neural tube.

genetics↗

bioRxiv2022

A method for polyclonal antigen-specific T cell-targeted genome editing (TarGET) for adoptive cell therapy applications

Adoptive cell therapy of donor-derived, antigen-specific T cells expressing native T cell receptors (TCRs) is a powerful strategy to fight viral infections in immunocompromised patients. Determining the fate of T cells following patient infusion hinges on the ability to track them in vivo. While this is possible by genetic labeling of parent cells, the applicability of this approach has been limited by the non-specificity of the edited T cells. Here, we devised a method for CRISPR-targeted genome integration of a barcoded gene into Epstein-Barr virus-antigen-stimulated T cells and demonstrated its use for exclusively identifying expanded virus-specific cell lineages. Our method facilitated the enrichment of antigen-specific T cells, which then mediated improved cytotoxicity against EBV-transformed target cells. Single-cell and deep sequencing for lineage tracing revealed the expansion profile of specific T cell clones and their corresponding gene expression signature. This method has the potential to enhance the traceability and the monitoring capabilities during immunotherapeutic T cell regimens.

immunology↗

bioRxiv2021

speedingCARs: accelerating the engineering of CAR T cells by signaling domain shuffling and single-cell sequencing

Chimeric antigen receptors (CARs) consist of an extracellular antigen-binding region fused to intracellular signaling domains, thus enabling customized T cell responses against target cells. Due to the low-throughput process of systematically designing and functionally testing CARs, only a small set of immune signaling domains have been thoroughly explored, despite their major role in T cell activation, effector function and persistence. Here, we present speedingCARs, an integrated method for engineering CAR T cells by signaling domain shuffling and functional screening by single-cell sequencing. Leveraging the inherent modularity of natural signaling domains, we generated a diverse library of 180 unique CAR variants, which were genomically integrated into primary human T cells by CRISPR-Cas9. Functional and pooled screening of the CAR T cell library was performed by co-culture with tumor cells, followed by single-cell RNA sequencing (scRNA-seq) and single-cell CAR sequencing (scCAR-seq), thus enabling high-throughput profiling of multi-dimensional cellular responses. This led to the discovery of several CAR variants that retained the ability to kill tumor cells, while also displaying diverse transcriptional signatures and T cell phenotypes. In summary, speedingCARs substantially expands and characterizes the signaling domain combinations suited for CAR design and supports the engineering of next-generation T cell therapies.

synthetic biology↗

bioRxiv2021

A single-cell atlas of lymphocyte adaptive immune repertoires and transcriptomes reveals age-related differences in convalescent COVID-19 patients

COVID-19 disease outcome is highly dependent on adaptive immunity from T and B lymphocytes, which play a critical role in the control, clearance and long-term protection against SARS-CoV-2. To date, there is limited knowledge on the composition of the T and B cell immune receptor repertoires [T cell receptors (TCRs) and B cell receptors (BCRs)] and transcriptomes in convalescent COVID-19 patients of different age groups. Here, we utilize single-cell sequencing (scSeq) of lymphocyte immune repertoires and transcriptomes to quantitatively profile the adaptive immune response in COVID-19 patients of varying age. We discovered highly expanded T and B cells in multiple patients, with the most expanded clonotypes coming from the effector CD8+ T cell population. Highly expanded CD8+ and CD4+ T cell clones show elevated markers of cytotoxicity (CD8: PRF1, GZMH, GNLY; CD4: GZMA), whereas clonally expanded B cells show markers of transition into the plasma cell state and activation across patients. By comparing young and old convalescent COVID-19 patients (mean ages = 31 and 66.8 years, respectively), we found that clonally expanded B cells in young patients were predominantly of the IgA isotype and their BCRs had incurred higher levels of somatic hypermutation than elderly patients. In conclusion, our scSeq analysis defines the adaptive immune repertoire and transcriptome in convalescent COVID-19 patients and shows important age-related differences implicated in immunity against SARS-CoV-2.

immunology↗

bioRxiv2021

Single-cell sequencing of plasma cells from COVID-19 patients reveals highly expanded clonal lineages produce specific and neutralizing antibodies to SARS-CoV-2

Isolation and characterization of antibodies in COVID-19 patients has largely focused on memory B cells, however it is the antibody-secreting plasma cells that are directly responsible for the production of serum antibodies, which play a critical role in controlling and resolving SARS-CoV-2 infection. To date there is little known about the specificity of plasma cells in COVID-19 patients. This is largely because plasma cells lack surface antibody expression, which complicates their screening. Here, we describe a technology pipeline that integrates single-cell antibody repertoire sequencing and high-throughput mammalian display screening to interrogate the specificity of plasma cells from 16 convalescent COVID-19 patients. Single-cell sequencing allows us to profile antibody repertoire features in these patients and identify highly expanded clonal lineages. Mammalian display screening is employed to reveal that 37 antibodies (out of 132 candidates) derived from expanded plasma cell clonal lineages are specific for SARS-CoV-2 antigens, including antibodies that target the receptor binding domain (RBD) with high affinity and exhibit potent neutralization of SARS-CoV-2. One Sentence SummarySingle-cell antibody repertoire sequencing and high-throughput screening identifies highly expanded plasma cells from convalescent COVID-19 patients that produce SARS-CoV-2-specific antibodies capable of potent neutralization.

immunology↗

bioRxiv2020

A functional screening platform for engineering chimeric antigen receptors with reduced on-target, off-tumour activation

Chimeric antigen receptor (CAR) T cell therapies have advanced substantially in the clinic for cancer immunotherapy. However, challenges related to safety persist; one major concern is when CARs respond to antigen present on healthy cells (on-target, off-tumour response). A strategy to ameliorate this consists in engineering the affinity of CARs such that they are only activated by tumor cells expressing high antigen levels. Here, we developed a CAR T cell display platform for functional screening based on cell signaling. Starting with a CAR with high affinity towards its target antigen, we used CRISPR-Cas9 genome editing to generate a library of antigen-binding domain variants. Following multiple rounds of functional screening and deep sequencing-guided selection, CAR variants were identified that were discriminatively activated by tumor cells based on antigen expression levels. Our platform demonstrates how directed evolution based on functional screening can be used to enhance the selectivity and safety of CARs.

immunology↗