Biology subjects

Nahmad, A. D.

Publications and source records attributed to Nahmad, A. D..

4 recordsLinked to original sources

bioRxiv2025

Differential effects of immobilized CCL21 and ICAM1 on TILs with distinct expansion properties

Adoptive T cell therapy (ACT), particularly tumor-infiltrating lymphocyte (TIL), holds great promise for cancer treatment, yet it still faces major challenges such as variability in expansion rates, cytotoxic potency and immune suppression. Recent studies suggest that a "synthetic immune niche" (SIN), composed of immobilized CCL21 and ICAM-1, enhances both the expansion and cytotoxicity of murine and patient-derived T cells. Here, we investigate the mechanism underlying the expansion variability by identifying morphological and molecular markers that distinguish low- and high-expanding TILs and predict their ex vivo expansion potential. We further developed novel SIN-based strategies that differentially reinforce the efficacy of both low- and high-expanding TILs. We demonstrate that a 14-day REP with feeder cells and SIN facilitates the proliferation of the low-expanding cells, while the high-expanding counterparts benefit from a sequential expansion protocol of 7 days with feeder cells only, followed by 7 days with SIN treatment. At the end of the REP both TIL populations display high levels of granzyme B and perforin and reduced levels of exhaustion markers. In conclusion, our findings demonstrate that the refined CCL21+ICAM1 SIN treatment improves expansion rates and activation profiles of both TIL populations, thereby enabling personalized SIN-enhanced protocols for TIL-based immunotherapy.

bioengineering↗

bioRxiv2021

Frequent Aneuploidy in Primary Human T Cells Following CRISPR-Cas9 cleavage

Multiple ongoing clinical trials use site-specific nucleases to disrupt T cell receptor (TCR) genes in order to allow for allogeneic T cell therapy1-5. In particular, the first U.S. clinical trial using CRISPR-Cas9 entailed the targeted disruption of the TCR chains and programmed cell death protein 1 (PDCD1) in T cells of refractory cancer patients6. Here, we used the same guide RNA sequences and applied single-cell RNA sequencing (scRNAseq) to more than 7000 primary human T cells, transfected with CRISPR-Cas9. Four days post-transfection, we found a loss of chromosome 14, harboring the TCR locus, in up to 9% of the cells, and a chromosome 14 gain in up to 1.4% of the cells. We further identified truncations of chromosome 7, harboring the TCR{beta} locus, in 9.9% of the cells. Loss of heterozygosity (LOH) was further validated using fluorescence in situ hybridization (FISH) and the temporal dynamics of cleavage and incomplete repair were monitored using digital droplet PCR (ddPCR). Aneuploidy was found among all T cell subsets and was associated with transcriptional signatures of reduced proliferation and metabolism as well as with induced p53 activation and cell death. We conclude that aneuploidy and chromosomal truncations are frequent outcomes of CRISPR-Cas9 cleavage in clinical protocols. Monitoring and minimizing these aberrant products is crucial for future applications of genome editing in T cell engineering and beyond.

bioengineering↗

bioRxiv2021

In vivo engineered B cells retain memory and secrete high titers of anti-HIV antibodies in mice

As a potential single-shot HIV therapy, transplanted engineered B cells allow robust secretion of broadly neutralizing antibodies (bNAbs). However, ex vivo engineering of autologous B cells is expensive and requires specialized facilities, while allogeneic B cell therapy necessitates MHC compatibility. Here, we develop in vivo B cell engineering, by injecting two adeno associated viral vectors, one coding for saCas9 and another coding for a bNAb. Following immunizations, we demonstrate memory retention and bNAb secretion at neutralizing titers. We observed minimal CRISPR/Cas9 off-target cleavage, using unbiased CHANGE-Seq analysis, while on-target cleavage at undesired tissues is reduced by expressing saCas9 from a B cell specific promoter. In vivo B cell engineering is thus a safe, potent and scalable method for expressing desired antibodies against HIV and beyond. One sentence summaryB cells can be engineered in vivo to robustly secrete anti-HIV bNAbs in a safe, durable and scalable manner.

immunology↗

bioRxiv2020

B cells engineered to express an anti-HIV antibody allow memory retention, class switch recombination and clonal selection in mice

HIV viremia can be controlled by chronic antiretroviral therapy. As a potentially single-shot alternative, B cells engineered by CRISPR/Cas9 to express anti-HIV broadly neutralizing antibodies (bNAbs) were shown capable of secreting high antibody titers. Here, we demonstrate that, upon immunization of mice, adoptively transferred engineered B cells home to germinal centers (GC) where they predominate over the endogenous response and differentiate into memory and plasma cells while undergoing class switch recombination (CSR). Immunization with a higher affinity antigen increases accumulation in GCs and CSR rates. Boost immunization increases rates of engineered B cells in GCs and antibody secretion, indicating memory retention. Finally, antibody sequences of engineered B cells in the spleen show patterns of clonal selection. B cells may thus be engineered as a living and evolving drug.

immunology↗